Air filtration devices are well known and are used to remove impurities, such as particulates, from the surrounding air. Typical air filtration devices include a fan assembly and a filter assembly including one or more filters. When one of these air filtration devices is operating, the fan assembly pulls or pushes air surrounding the air filtration device through the filter assembly. As the air flows through the filter assembly, the filter(s) captures various impurities and removes them from the air. The filtered air is then expelled from the air filtration device.
One known air filtration device includes a controller that uses a proportional-integral-derivative (PID) control module to ensure the fan operates at a desired fan speed. The PID control module controls how much electrical current is supplied to the fan motor. The amount of electrical current supplied to the fan motor controls the fan speed.
The controller provides the PID control module the following two inputs that enable it to perform this function: (1) the desired fan speed (e.g., as input by the user); and (2) a measured fan speed. The controller determines the measured fan speed by: (1) determining ΔT, which approximates the time it takes the fan blade of the fan to make one complete revolution (based on the output of a fan-speed sensor); and (2) inverting ΔT (i.e., calculating 1/ΔT), which provides the measured fan speed in units of revolutions per unit of time of ΔT (e.g., minutes, seconds, etc.).
The PID control module then determines whether the measured fan speed matches the desired fan speed.
If the measured fan speed does not match the desired fan speed, the PID control module determines how to vary the electrical current supplied to the fan motor to correct the error. For instance, if the measured fan speed is less than the desired fan speed, the PID control module determines to increase the electrical current supplied to the fan motor to cause the fan to spin faster to reach the desired fan speed. But if the measured fan speed is greater than the desired fan speed, the PID control module determines to decrease the electrical current supplied to the fan motor to cause the fan to spin slower to reach the desired fan speed.
As noted above, the controller determines ΔT based on the output of the fan-speed sensor. Ideally, the fan-speed sensor would trip only once per fan blade revolution and, upon each fan-speed sensor trip, the controller would read a free-running timer. In this ideal scenario, since the free-running timer resets to zero following each fan-speed sensor trip, the free-running-timer reading would equal ΔT (i.e., the time elapsed between that fan-speed sensor trip and the immediately previous fan-speed sensor trip, which is the time it took the fan blade to complete one revolution). This way of determining ΔT based on an assumed ideal scenario can be problematic.
One problem with determining ΔT based on an assumed ideal scenario is that the fan-speed sensor may trip more than once per revolution of the fan blade (i.e., the ideal scenario of one fan-speed sensor trip per revolution doesn't exist). For example, if tape on the fan blade trips an optical fan-speed sensor, both the leading and trailing edges of the tape may trip the fan-speed sensor when rotating past it. In this instance, the time elapsed between two consecutive trips of the fan-speed sensor (the leading edge tripping the fan-speed sensor immediately followed by the trailing edge tripping the fan-speed sensor) would be much less than the time it takes the fan blade to complete a single revolution at the desired fan speed. And inverting this time elapsed (i.e., ΔT) would result in a measured fan speed that is much higher than the actual fan speed. This would cause the PID control module to determine to control the electrical current supplied to the fan in an undesired way by unnecessarily decreasing the fan speed. This renders the above-described way of determining the measured fan speed inaccurate, leading to non-ideal fan operation.
In one example in which the desired fan speed is 1,000 RPMs and the actual fan speed is 1,000 RPMs, in an ideal scenario, the free-running timer reads 0.001 minutes when the fan-speed sensor trips after the fan blade completes a revolution. Since ΔT is 0.001 minutes, 0.001 minutes elapsed between the previous two consecutive trips of the fan-speed sensor. The controller determines a measured fan speed of 1,000 revolutions per minute (RPMs) by inverting this 0.001 minute ΔT and inputs this measured fan speed to the PID control module. Since the measured fan speed equals the desired fan speed, the PID control module does not vary the electrical current supplied to the fan motor.
Modifying the above example for a non-ideal scenario, the free-running timer reads 0.0001 minutes when the fan-speed sensor trips after the fan blade completes a fraction of a revolution. Since ΔT is 0.0001 minutes, 0.0001 minutes elapsed between the previous two consecutive trips of the fan-speed sensor. The controller determines a measured fan speed of 10,000 RPMs by inverting this 0.0001 minute ΔT and inputs this measured fan speed to the PID control module. Since the measured fan speed is 10× larger than the desired fan speed, the PID control module determines to decrease the electrical current supplied to the fan motor to decrease the fan speed. This is problematic because, in reality, the actual fan speed matches the desired fan speed, and the inaccurate measured fan speed (based on the inaccurate ΔT) input to the PID control module causes an unnecessary and undesired decrease in the fan speed.
Another problem with determining ΔT based on an assumed ideal scenario is that the fan-speed sensor may not trip during a revolution of the fan blade (i.e., the ideal scenario of one fan-speed sensor trip per revolution doesn't exist). For example, debris may block the fan-speed sensor and cause it to fail to sense the tape on the fan blade rotating past it. In this instance, the time elapsed between two consecutive trips of the fan-speed sensor would be much greater than the time it took the fan blade to complete a single revolution. And inverting this time elapsed (i.e., ΔT) would result in a measured fan speed that is much lower than the actual fan speed. This would cause the PID control module to determine to control the electrical current supplied to the fan in an undesired way by unnecessarily increasing the fan speed. This renders the above-described way of determining the measured fan speed inaccurate, leading to non-ideal fan operation.
In one example in which the desired fan speed is 1,000 RPMs and the actual fan speed is 1,000 RPMs, in an ideal scenario, the free-running timer reads 0.001 minutes when the fan-speed sensor trips after the fan blade completes a revolution. Since ΔT is 0.001 minutes, 0.001 minutes elapsed between the previous two consecutive trips of the fan-speed sensor. The controller determines a measured fan speed of 1,000 revolutions per minute (RPMs) by inverting this 0.001 minute ΔT and inputs this measured fan speed to the PID control module. Since the measured fan speed equals the desired fan speed, the PID control module does not vary the electrical current supplied to the fan motor.
Modifying the above example for a non-ideal scenario, the free-running timer reads 0.002 minutes when the fan-speed sensor trips after the fan blade completes two consecutive revolutions. Since ΔT is 0.002 minutes, 0.002 minutes elapsed between the previous two consecutive trips of the fan-speed sensor. The controller determines a measured fan speed of 500 RPMs by inverting this 0.002 minute ΔT and inputs this measured fan speed to the PID control module. Since the measured fan speed is half the desired fan speed, the PID control module determines to increase the electrical current supplied to the fan motor to increase the fan speed. This is problematic because, in reality, the actual fan speed matches the desired fan speed, and the inaccurate measured fan speed (based on the inaccurate ΔT) input to the PID control module causes an unnecessary and undesired increase in the fan speed.
Another problem with determining ΔT based on an assumed ideal scenario is that determining ΔT in this manner doesn't account for run-up to the desired fan speed just after a user powers the air filtration device on. When the user powers the air filtration device on, the fan is not moving. Once the user selects a desired fan speed, the controller controls the fan motor to begin rotating the fan blade and ramp it up to the desired fan speed. Initially, the fan blade rotates (relatively) slowly, so it takes a (relatively) long time for the fan blade to make full revolutions. Inputting this small measured fan speed to the PID control module would result in the same problems described above: an unnecessary increase in electrical current supplied to the fan motor.
Accordingly, there is a need for new and improved air filtration devices that solve these problems.
The present disclosure describes an air filtration device that operates a fan-speed sensor error elimination process. The air filtration device uses a PID control module to ensure its fan operates at a desired fan speed. The fan-speed sensor error elimination process ensures that the air filtration device's controller does not send a measured fan speed determined using data that represent the time it takes the fan blade to complete a fraction of a revolution to the PID control module. This ensures the PID control module accurately controls electrical current supplied to the fan motor.
Additional features and advantages are described in, and will be apparent from, the following Detailed Description and the Figures.
Referring now to the drawings,
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The base 2110 includes: (a) a generally cylindrical exterior side surface 2112 to which the stabilizers 2120, 2130, and 2140 are attached; (b) a generally annular exterior upper surface including a plurality of surfaces to which various other components of the air filtration device are mounted (described below); (c) a generally cylindrical interior side surface 2116a ; and (d) a generally annular interior upper surface 2116b. The interior side surface 2116a and the interior top surface 2116b generally define a fan assembly mounting chamber on the underside of the base 2110.
Turning to the exterior of the base 2110, as best shown in
In this example embodiment, the base 2110 defines fastener receiving openings 2114a, 2114b, 2114c , and 2114d at least partially therethrough. The fastener receiving opening 2114a is partially defined through the third section 2115a of the air director mounting surface 2115, the fastener receiving opening 2114b is partially defined through the first section 2115c of the air director mounting surface 2115, the fastener receiving opening 2114c is partially defined through the fourth section 2115c of the air director mounting surface 2115, and the fastener receiving opening 2114d is partially defined through the second section 2115d of the air director mounting surface 2115. The fastener receiving openings 2114 are substantially equally circumferentially spaced around a vertical axis through the center of the base 2110.
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Turning to the interior of the base 2110, as best shown in
The stabilizers 2120, 2130, and 2140 facilitate attachment of the locking cover 2200 to the lower housing component 2100, provide structural support for the air filtration device 2010, and provide protection for the dual filter assembly. Additionally, as best shown in
To facilitate attachment of the locking cover 2200 to the lower housing component 2110, in this example embodiment, each of the stabilizers 2120, 2130, and 2140 includes a locking cover mounting tab 2121, 2131, and 2141, respectively, and a latch mounting surface 2129, 2139, and 2149, respectively. The locking cover mounting tabs 2121, 2131, and 2141 are received by the locking cover 2200 (described below) and, thereafter, prevent the locking cover 2200 from rotating with respect to the lower housing component 2100. As shown in
In this example embodiment, side 2143 of the stabilizer 2140 includes a recessed control panel mounting surface 2144 to which an integrated control panel 2160 is attached. The control panel 2160, which is shown in
Additionally, in this example embodiment, side 2122 of the stabilizer 2120 includes a recessed power panel mounting surface 2123 to which a power panel 2170 is attached. The power panel 2170, which is shown in
In other embodiments, the air filtration device includes fewer electrical outlets, more electrical outlets, or no electrical outlets. In other embodiments, the air filtration device is operable using any suitable power source other than and/or in addition to an A/C power source, such as one or more replaceable or rechargeable batteries.
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In this example embodiment, the lower housing component is dual-walled and rotationally molded out of plastic, though the lower housing component may be made of any suitable material(s) or manufactured in any suitable manner(s).
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In this example embodiment, the exhaust screen 2400 is an injection molded plastic component, though the exhaust screen may be made of any suitable material or materials or manufactured in any suitable manner or manners.
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In this example embodiment, the fan assembly mounting chamber cover 2500 is a thin walled plastic component, though the fan assembly mounting chamber cover may be made of any suitable material.
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The annular portion 3110 defines fastener receiving openings 3110a , 3110b, 3110c , and 3110d therethrough. In this example embodiment, the fastener receiving openings 3110a, 3110b, 3110c , and 3110d are substantially equally circumferentially spaced around a vertical axis through the center of the annular portion 3110. As best shown in
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The upper and lower end caps 2620 and 2630 each have an exterior diameter De and an interior diameter Di. As best shown in
In this example embodiment, both the upper and lower end caps of the HEPA filter include a specific geometry that enables airtight sealing when the HEPA filter is installed. As will be explained in detail below, this specific end cap geometry and, more specifically, the manner in which the end cap geometry enables an airtight seal to be formed, enables the air filtration device to accurately measure various pressures and perform certain functions using those measured pressures. In this example embodiment, the end caps of the HEPA filter are made of molded urethane, though the end caps may be made of any suitable material. While the end caps are substantially identical in this example embodiment, in other embodiments the upper and lower end caps may have different geometries. Further, in this example embodiment, the outer protective mesh is made of plastic and the inner protective mesh is made of a thin gage metal, though the protective mesh may be made of any suitable material.
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The brace 2710 includes an annular, downwardly embossed HEPA filter securing plate nesting surface 2712 (with respect to the orientation shown in
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This above process is performed twice, resulting in two sheets of rigidized pre-filter media 2910 and 2930. The pre-filter body of the pre-filter 2900 is formed by sewing (e.g., attaching via stitching) the corresponding side edges of the two sheets of rigidized pre-filter media 2910 and 2930 to one another to form an annular or ring-shaped structure (as shown in
In this example embodiment, the pre-filter limit switch actuator 2990 includes a generally rectangular head 2991 and an actuator 2992 extending therefrom. The head 2991 defines a plurality of attachment openings 2993 therethrough. In this embodiment, the pre-filter limit switch actuator 2990 is attached to the pre-filter body the pre-filter 2900 via the attachment openings 2993 (such as by sewing, adhesive, fastener, or any other suitable manner of attachment) such that the head 2991 contacts the exterior surface of the pre-filter body of the pre-filter 2900 and the pre-filter limit switch actuator 2992 extends below the lower edge of the pre-filter body of the pre-filter 2900 formed by the lower edges 2914 and 2934 of the sheets of rigidized pre-filter material 2910 and 2930. The pre-filter sensor limit switch actuator 2990 is sized to actuate the pre-filter limit switch, as described above, which enables the air filtration device to determine whether an acceptable pre-filter is installed. The pre-filter limit switch actuator may take any suitable shape, be made of any suitable material, and attached at any suitable location on the pre-filter body.
In this example embodiment, the pre-filter media is a polyspun material, though any suitable filter media may be employed. Additionally, in this example embodiment, the rigidized backing includes nylon mesh, though any suitable material may be employed, such as a material including vertical, horizontal, or diagonal boning. In this example embodiment, the combination of the polyspun material and the nylon mesh renders the pre-filter flexible enough to fold flat for shipping but rigid enough to support itself and to enable the pre-filter to be slid over and onto the HEPA filter. In other embodiments, a single sheet of rigidized pre-filter media is created and formed into an annular or oval-shaped structure by sewing the two sides of that sheet of rigidized pre-filter media together. That is, in such embodiments, the formation of the pre-filter body causes the pre-filter body to include a single seam. The sides of the rigidized pre-filter media may be joined in any suitable manner other than or in addition to sewing, such as by a heat seal or adhesive.
The pre-filter body of the pre-filter 9900a is formed by sewing the side edges of the sheet of rigidized pre-filter media 9910 to one another to form an annular or ring-shaped structure (as shown in
Put differently, in this example embodiment, an upper portion of the rigidized backing is disposed between a first portion of the pre-filter media and a second portion of the pre-filter media, and the first portion of the pre-filter media, the upper portion of the rigidized backing, and the second portion of the pre-filter media are attached via stitching. Additionally, a lower portion of the rigidized backing is disposed between a third portion of the pre-filter media and a fourth portion of the pre-filter media, and the third portion of the pre-filter media, the lower portion of the rigidized backing, and the fourth portion of the pre-filter media are attached via stitching. Further, the first portion of the pre-filter media is connected to the second portion of the pre-filter media and the third portion of the pre-filter media is connected to the fourth portion of the pre-filter media. Additionally, the second portion of the pre-filter media is connected to the third portion of the pre-filter media. Further, the first portion of the pre-filter media terminates in a first free end and the fourth portion of the pre-filter media terminates in a second free end.
In this example embodiment, as shown in
In this example embodiment, the pre-filter media is a polyspun material, though any suitable filter media may be employed. Additionally, in this example embodiment, the rigidized backing includes nylon mesh, though any suitable material may be employed, such as a material including vertical, horizontal, or diagonal boning. In this example embodiment, the combination of the polyspun material and the nylon mesh renders the pre-filter flexible enough to fold flat for shipping but rigid enough to support itself and to enable the pre-filter to be slid over and onto the HEPA filter.
In this example embodiment, the pre-filter 9900b also includes a pre-filter limit switch actuator 9990b. The pre-filter limit switch actuator 9990b is “T-shaped” and includes a generally rectangular head 9991b and an actuator 9992b extending transversely therefrom (such as substantially perpendicularly therefrom). In this embodiment, the head 9991b of the pre-filter limit switch actuator 9990b is disposed within the lower folded-over portion (with respect to the orientation shown in
In this embodiment, the pre-filter limit switch actuator 9990b is inserted within the lower folded-over portion before the lower folded-over portion is sewn in place. In one embodiment, the head fills or substantially fills the entire space within the lower folded-over portion, which minimizes movement of the head within the lower folded-over portion The pre-filter limit switch actuator may take any suitable shape; be made of any suitable material (such as plastic); and be attached at any suitable location on the pre-filter body, such as any suitable location around the circumference of the pre-filter body. For instance, in other embodiments, the head of the pre-filter limit switch actuator may be disc-shaped, square-shaped, sphere-shaped, cylindrically-shaped, and the like.
Put differently, in this example embodiment, an upper portion of the rigidized backing is disposed between a first portion of the pre-filter media and a second portion of the pre-filter media, and the first portion of the pre-filter media, the upper portion of the rigidized backing, and the second portion of the pre-filter media are attached via stitching. Additionally, a lower portion of the rigidized backing is disposed between a third portion of the pre-filter media and a fourth portion of the pre-filter media, and the third portion of the pre-filter media, the lower portion of the rigidized backing, and the fourth portion of the pre-filter media are attached via stitching. Further, the first portion of the pre-filter media is connected to the second portion of the pre-filter media and the third portion of the pre-filter media is connected to the fourth portion of the pre-filter media. Additionally, the second portion of the pre-filter media is connected to the third portion of the pre-filter media. Further, the first portion of the pre-filter media terminates in a first free end and the fourth portion of the pre-filter media terminates in a second free end. In this embodiment, the head of the limit switch actuator is disposed between the third portion of the filter media and the fourth portion of the filter media and the actuator extends through the filter media proximate the lower edge of the body.
In this example embodiment, the pre-filter media is a polyspun material, though any suitable filter media may be employed. Additionally, in this example embodiment, the rigidized backing includes nylon mesh, though any suitable material may be employed, such as a material including vertical, horizontal, or diagonal boning. In this example embodiment, the combination of the polyspun material and the nylon mesh renders the pre-filter flexible enough to fold flat for shipping but rigid enough to support itself and to enable the pre-filter to be slid over and onto the HEPA filter.
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In this example embodiment, the locking cover is a rotationally molded plastic component. It should be appreciated, however, that the locking cover may be made of any suitable material or materials or manufactured in any suitable manner or manners.
In this example embodiment, each fastener receiving opening of the lower housing component 2100 either: (a) is a threaded fastener receiving opening configured to receive a threaded fastener, or (b) includes an integrated threaded insert (formed into the component or inserted after the component is formed) configured to receive a threaded fastener. It should be appreciated, however, that any suitable fastening mechanisms may be employed to attach the components of the air filtration device to one another.
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The exhaust screen 2400 and the fan assembly mounting chamber cover 2500 are attached to the base 2110 by: (a) positioning the exhaust screen 2400 such that the flange 2453 is partially disposed within the exhaust screen mounting channel 2153, the base mounting surface 2454a abuts the exhaust screen mounting surface 2154 of the base 2110, and the base mounting surface 2455a abuts the exhaust screen mounting surface 2155 of the base 2110; (b) positioning the fan assembly mounting chamber cover 2500 such that the exhaust screen mounting surface 2554 abuts the fan assembly mounting chamber cover mounting surface 2454b of the exhaust screen 2400 and the exhaust screen mounting surface 2555 abuts the fan assembly mounting chamber cover mounting surface 2455b of the exhaust screen 2400; (c) inserting a fastener through the fastener receiving opening 2524a of the fan assembly mounting chamber cover 2500 and the fastener receiving opening 2456 of the exhaust screen 2400 and threading that fastener into the fastener receiving opening 2154a of the base 2110; (d) inserting a fastener through the fastener receiving opening 2524b of the fan assembly mounting chamber cover 2500 and the fastener receiving opening 2457 of the exhaust screen 2400 and threading that fastener into the fastener receiving opening 2155a of the base 2110; and (e) inserting fasteners through the fastener receiving openings 2514 of the fan assembly mounting chamber cover 2500 and threading those fasteners into the corresponding fastener receiving openings 2118 of the base 2110.
Once the fan assembly mounting chamber cover is attached to the base, the fan assembly mounting chamber cover substantially covers the fan assembly mounting chamber and encloses the fan assembly and the fan assembly mounting bracket within the fan assembly mounting chamber. Additionally, once the fan assembly mounting chamber cover is mounted to the base, the exhaust port upper portion of the base and the exhaust port lower portion of the fan assembly mounting chamber cover form an exhaust port that defines an exhaust channel.
In this example embodiment, the exhaust port is substantially parallel to a plane extending between the stabilizers 2120 and 2130. This angle of the exhaust port improves fan efficiency by eliminating turbulence and back pressure within the fan assembly mounting chamber. Further, the fact that the exhaust port is substantially parallel to a plane extending between the stabilizers 2120 and 2130 ensures that the air filtration device will expel the filtered air substantially parallel to the ground regardless of whether the air filtration device is operating in an upright orientation or on its side (i.e., resting on the stabilizers 2120 and 2130).
The air director 3100 is attached to the base 2110 by: (a) positioning the air director 3100 such that the air director mounting surfaces 3112b and 3114b abut the first and second opposing sections 2115b and 2115d, respectively, of the air director mounting surface 2115 of the exterior upper surface of the base 2110; (b) inserting a fastener through the fastener receiving opening 3110a of the air director 3100 and threading that fastener into the fastener receiving opening 2114a of the base 2110; and (c) inserting a fastener through the fastener receiving opening 3110c of the air director 3100 and threading that fastener into the fastener receiving opening 2114c of the base 2110. The use of the air director to direct air drawn through the filters into the fan assembly improves fan efficiency.
The HEPA filter securing bracket 2700 is mounted to the base 2110 by: (a) positioning the first and second HEPA filter securing bracket mounting tabs 2740 and 2750 atop the HEPA filter mounting bracket mounting surfaces 3112a and 3114a, respectively, of the air director 3100; (b) inserting a fastener through the fastener receiving opening 2740a of the HEPA filter mounting bracket and through the fastener receiving opening 3110b of the air director 3100 and threading that fastener into the fastener receiving opening 2114b of the base 2110; and (c) inserting a fastener through the fastener receiving opening 2750a of the HEPA filter mounting bracket and the fastener receiving opening 3110d of the air director 3100 and threading that fastener into the fastener receiving opening 2114d of the base 2110.
To install the HEPA filter 2600, the HEPA filter 2600 is positioned around the HEPA filter securing bracket 2700 and onto the base 2110 such that the lower end cap 2630 of the HEPA filter 2600 rests within the HEPA filter mounting channel. More specifically, as illustrated in
The HEPA filter securing plate 2800 is then attached to the HEPA filter securing bracket 2700 by: (a) nesting the second annular bridging portion 2840 and the third annular portion 2850 of the HEPA filter securing plate 2800 within the HEPA filter securing plate nesting surface 2712 of the brace 2710 of the HEPA filter securing bracket 2700; and (b) inserting a fastener through the fastener receiving opening 2850a of the HEPA filter securing plate 2800 and threading that fastener into the fastener receiving opening 2715a of the nut 2715 of the HEPA filter securing bracket 2700.
As best shown in
The pre-filter 2900 is installed by aligning the pre-filter limit switch actuator 2990 with the pre-filter limit switch actuator receiving opening 2175 of the base 2110 and press-fitting the pre-filter 2900 downward into the pre-filter securing channel of the base 2110 until the pre-filter limit switch actuator 2990 actuates the pre-filter limit switch.
The locking cover 2220 is attached to the lower housing component 2100 by: (a) positioning the locking cover 2200 atop the stabilizers such that the locking cover mounting tab receiving opening defined by the surface 2221 of the mount 2220 receives the locking cover mounting tab 2121 of the stabilizer 2120, the locking cover mounting tab receiving opening defined by the surface 2231 of the mount 2230 receives the locking cover mounting tab 2131 of the stabilizer 2130, and the locking cover mounting tab receiving opening defined by the surface 2241 of the mount 2240 receives the locking cover mounting tab 2141 of the stabilizer 2140; and (b) securing the latches attached to the stabilizers to their respective latch strikes of the locking cover 2200. Once the locking cover is attached to the lower housing component, the user may carry or otherwise transport the air filtration device via the handle 2212.
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In another embodiment, the locking cover is attached to one of the stabilizers of the lower housing component via a hinge. Thus, in this embodiment, the locking cover is not completely detachable from the lower housing component. Rather, to remove the filters in this embodiment, the latches are unlocked and the locking cover is rotated via the hinge off of the lower housing component to provide access to the filters. In other embodiments, the locking cover attaches to the stabilizers in any suitable manner, such as through the use of threaded fasteners.
In this example embodiment, to replace the pre-filter the user detaches the locking cover from the lower housing component, removes the old pre-filter, and installs a new pre-filter as described above, and attaches the locking cover to the lower housing component. To replace the HEPA filter, the user detaches the locking cover from the lower housing component, detaches the HEPA filter securing plate from the HEPA filter securing bracket, removes the old HEPA filter, installs a new HEPA filter as described above, attaches the HEPA filter securing plate to the HEPA filter securing bracket, and attaches the locking cover to the lower housing component. It should be appreciated that, in this example embodiment, the pre-filter and the HEPA filter are separately replaceable.
The geometry of the base, the locking cover, and the HEPA filter end caps that enable airtight sealing when the HEPA filter is installed eliminates need to include an additional gasket to ensure proper sealing. It should also be appreciated that the geometry of the pre-filter securing channels provides improved sealing when the pre-filter is installed. It should further be appreciated that the fact that: (a) the pre-filter securing channel of the lower housing component is lower relative to the HEPA filter mounting channel of the lower housing component, and (b) the pre-filter securing channel of the locking cover is higher than the HEPA filter mounting channel of the locking cover improves the accuracy of the measurements taken by the pressure sensors.
In this example embodiment, the controller 3650: (1) communicates with each of the other electronic components, (2) receives communications from each of the other electronic components, and (3) controls each of the other electronic components. The controller may be any suitable processing device or set of processing devices, such as a microprocessor, a microcontroller-based platform, a suitable integrated circuit, one or more application-specific integrated circuits (ASICs), or any other suitable circuit boards.
In certain embodiments, the controller of the air filtration device is configured to communicate with, configured to access, and configured to exchange signals with the at least one memory device or data storage device. In various embodiments, the at least one memory device includes random access memory (RAM), which can include non-volatile RAM (NVRAM), magnetic RAM (MRAM), ferroelectric RAM (FeRAM), and other suitable forms of RAM. In other embodiments, the at least one memory device includes read only memory (ROM). In certain embodiments, the at least one memory device includes flash memory and/or electrically erasable programmable read only memory (EEPROM). The at least one memory device may include any other suitable magnetic, optical, and/or semiconductor memory.
As generally described below, in various embodiments, the at least one memory device of the air filtration device stores program code and instructions executable by the controller of the air filtration device to control various processes performed by the air filtration device. The at least one memory device also stores other operating data, such as image data, event data, and/or input data. In various embodiments, part or all of the program code and/or the operating data described above is stored in at least one detachable or removable memory device including, but not limited to, a cartridge, a disk, a CD-ROM, a DVD, a USB memory device, or any other suitable non-transitory computer readable medium. In certain such embodiments, a user uses such a removable memory device to implement at least part of the present disclosure. In other embodiments, part or all of the program code and/or the operating data is downloaded to the at least one memory device of the air filtration device through any suitable data network (such as an internet, an intranet, or a cellular communications network).
In this example embodiment, the fan assembly 2300 is a RadiCal R2E250-RB02-15 centrifugal fan, though any other suitable fan assembly may be employed, such as the RadiCal R2E250-RB02-11.
In this example embodiment, the sound producing device 3850 is a Mallory Sonalert Products Inc. PB-1224PE-05Q sound producing device, though any suitable sound producing device may be employed. In this example embodiment, as described in detail below, the air filtration device uses the sound producing device 3850 to output the following audible tones: (a) a major air filtration device malfunction tone when the air filtration device determines that a major air filtration device malfunction occurs (described below), (b) a filter change alarm tone when the air filtration device determines that the pre-filter occlusion level exceeds the pre-filter shutdown threshold and needs replacement and/or when the HEPA filter occlusion level exceeds the HEPA filter shutdown threshold and needs replacement (as described below), and (c) a filter fault indicator tone when the air filtration device determines that an acceptable pre-filter is not installed and/or an acceptable HEPA filter is not installed (as described below).
In this example embodiment, the major air filtration device malfunction tone, the filter change alarm tone, and the filter fault tone are different. More specifically: (a) the major air filtration device malfunction tone includes a continuous tone; (b) the filter change alarm tone includes a one tone combination (beep-pause, beep-pause); and (c) the filter fault tone includes a two tone combination (beep-beep-pause, beep-beep-pause). In this example embodiment, setting the air filtration device to the standby operating mode or powering the air filtration device off causes the controller to silence the sound producing device 3850.
3.1 Control Panel
The operating mode selector 2161 enables the user to select the operating mode in which the user desires the air filtration device to operate. More specifically, in this example embodiment, the operating mode selector 2161 enables the user to select one of the following operating modes: one of the manual fan speed setting operating modes, the automatic fan speed setting selection operating mode, or the standby operating mode, each of which are described below. In this example embodiment, the operating mode selector 2161 includes a control knob that the user may rotate to indicate the desired operating mode.
In another embodiment, the operating mode selector includes a touch screen display that enables the user to select the desired operating mode by touching an appropriate area of the touch screen. The air filtration device sets the operating mode to the desired operating mode after receiving such input. In another embodiment, the operating mode selector includes a display and one or more associated buttons. In this embodiment, the user selects an operating mode by using the one or more buttons to select the desired operating mode. The air filtration device sets the operating mode to the desired operating mode after receiving such input.
In another embodiment, the air filtration device enables the user to use a computing device, such as (but not limited to) a cellular phone, a tablet computing device, a laptop computing device, and/or a desktop computing device, to select the desired operating mode. That is, in this embodiment: (a) the computing device receives an input of the user's desired operating mode; (b) the computing device communicates the user's desired operating mode to the air filtration device, such as (but not limited to) through a wireless network connection, a cellular network connection, a wired network connection, an infrared connection, or a Bluetooth connection; and (c) the air filtration device receives the communication from the computing device and sets the operating mode to the desired operating mode. It should be appreciated that, in this embodiment, the air filtration device enables the user to remotely change the operating mode of the air filtration device, such as from across the room or across the jobsite, which saves the time it would otherwise take the user to travel to the air filtration device to change the operating mode (such as via the control knob).
In another embodiment, the air filtration device enables the user to use a remote control to select the desired operating mode. That is, in this embodiment: (a) the remote control receives an input of the user's desired operating mode; (b) the remote control communicates the user's desired operating mode to the air filtration device, such as through any of the above-listed connections; and (c) the air filtration device receives the communication from the remote control and sets the operating mode to the desired operating mode. In one such embodiment, the remote control also displays one or more of the pre-filter fault indicator, the HEPA filter fault indicator, the air filtration device status indicator, the pre-filter status indicators, and the HEPA filter status indicators.
The air filtration device employs the pre-filter fault indicator 2162 to indicate that there is a problem with the pre-filter. In this example embodiment, the pre-filter fault indicator 2162 includes a red light-emitting diode (LED). As described in detail below, the air filtration device lights the red LED of the pre-filter fault indicator when any of: (a) an acceptable pre-filter is not installed; and (b) the pre-filter occlusion level exceeds the pre-filter shutdown threshold (i.e., when the pre-filter needs replacement). Any suitable pre-filter fault indicator(s) may be employed in addition to or instead of a red LED, such as (but not limited to): a different-colored LED, a light other than an LED, a display screen, a remote control display, a computing device, and/or a non-display indicator such as an audible tone.
The air filtration device employs the pre-filter status indicators 2163 to indicate the occlusion level of the pre-filter. In this example embodiment, the pre-filter status indicators 2163 include a green LED, a yellow LED, and a red LED. As described in detail below, the air filtration device: (a) lights the green LED of the pre-filter status indicators when the Clean pre-filter occlusion level range includes the determined pre-filter occlusion level; (b) lights the yellow LED of the pre-filter status indicators when the Slightly Occluded pre-filter occlusion level range includes the determined pre-filter occlusion level; (c) lights the red LED of the pre-filter status indicators when the Highly Occluded pre-filter occlusion level range includes the determined pre-filter occlusion level; and (d) lights the red LED of the pre-filter status indicators in a flashing or blinking manner when the pre-filter occlusion level range exceeds the pre-filter shutdown threshold (i.e., when the pre-filter needs replacement). Any suitable pre-filter status indicators may be employed in addition to or instead of green, yellow, and red LEDs, such as (but not limited to): a single LED that can display a plurality of different colors, different-colored LED, lights other than LEDs, one or more display screens, a remote control display, a computing device, and/or a non-display indicator such as an audible tone.
The air filtration device employs the HEPA filter fault indicator 2164 to indicate that there is a problem with the HEPA filter. In this example embodiment, the HEPA filter fault indicator 2164 includes a red LED. As described in detail below, the air filtration device lights the red LED of the HEPA filter fault indicator when any of: (a) an acceptable HEPA filter is not installed, and (b) the HEPA filter occlusion level exceeds the HEPA filter shutdown threshold (i.e., when the HEPA filter needs replacement). Any suitable HEPA filter fault indicator(s) may be employed in addition to or instead of a red LED, such as (but not limited to): a different-colored LED, a light other than an LED, a display screen, a remote control display, a computing device, and/or a non-display indicator such as an audible tone.
The air filtration device employs the HEPA filter status indicators 2165 to indicate the occlusion level of the HEPA filter. In this example embodiment, the HEPA filter status indicators 2165 include a green LED, a yellow LED, and a red LED. As described in detail below, the air filtration device: (a) lights the green LED of the HEPA filter status indicators when the Clean HEPA filter occlusion level range includes the determined HEPA filter occlusion level; (b) lights the yellow LED of the HEPA filter status indicators when the Slightly Occluded HEPA filter occlusion level range includes the determined HEPA filter occlusion level; (c) lights the red LED of the HEPA filter status indicators when the Highly Occluded HEPA filter occlusion level range includes the determined HEPA filter occlusion level; and (d) lights the red LED of the HEPA filter status indicators in a flashing or blinking manner when the HEPA filter occlusion level range exceeds the HEPA filter shutdown threshold (i.e., when the HEPA filter needs replacement). Any suitable HEPA filter status indicators may be employed in addition to or instead of green, yellow, and red LEDs, such as (but not limited to): a single LED that can display a plurality of different colors, different-colored LED, lights other than LEDs, one or more display screens, a remote control display, a computing device, and/or a non-display indicator such as an audible tone.
The air filtration device employs the air filtration device status indicator 2166 to indicate that the air filtration device is operating normally or to indicate that there is a problem with the air filtration device. In this example embodiment, the air filtration device status indicator 2166 includes an LED that can display a green or red light. As described in detail below, the air filtration device: (a) lights the LED of the air filtration device status indicator green when the air filtration device is operating in any of the manual fan speed setting operating modes, the automatic fan speed setting selection operating mode, or the standby operating mode; and (b) lights the LED of the air filtration device status indicator red when any of: (i) an acceptable pre-filter is not installed; (ii) an acceptable HEPA filter is not installed; (iii) the air filtration device is in shutdown mode and the automatic fan speed setting selection operating mode or the manual maximum fan speed setting operating mode is selected; (iv) the air filtration device is in shutdown mode, the manual medium fan speed setting operating mode or the manual minimum fan speed setting operating mode is selected, and the designated shutdown time period has expired; and (v) a major air filtration device malfunction occurs. In this example embodiment, whenever the air filtration device lights the LED of the air filtration device status indicator red, the power switch must be cycled “OFF” and back “ON” to clear the fault. In certain embodiments, when the air filtration device is in shutdown mode and the automatic fan speed setting selection operating mode or the manual maximum fan speed setting operating mode is selected such that the air filtration device lights the LED of the air filtration device status indicator red, the air filtration device clears the fault when the standby operating mode, the manual medium fan speed setting operating mode, or the manual minimum fan speed setting operating mode is selected.
Any suitable air filtration device status indicators may be employed in addition to or instead of an LED, such as (but not limited to): different-colored LED, lights other than LEDs, a plurality of LEDs, one or more display screens, a remote control display, and/or a computing device.
The air filtration device tracks or counts the number of hours the fan is operating at any fan speed and displays that number of hours on the hour meter display 2167. In this example embodiment, the hour meter display 2167 includes a six digit LED display. Additionally, in this example embodiment, the air filtration device does not enable a user to reset the hour count; the air filtration device retains the hour count when the power is disconnected (e.g., when the air filtration device is unplugged); and the air filtration device can roll over the hour counter once the hour meter display reaches a maximum displayed number of hours (such as 99999.9 hours for a six-digit hour meter display including one decimal place). The hour meter display may be any suitable indicator other than or in addition to a six-digit LED display.
In certain embodiments, the air filtration device communicates with a computing device of the user, such as (but not limited to) a cellular phone, a tablet computing device, a laptop computing device, and/or a desktop computing device, and causes the computing device to display certain information, such as one or more of: the pre-filter fault indicator, the HEPA filter fault indicator, the air filtration device status indicator, the pre-filter status indicators, the HEPA filter status indicators, and the selected operating mode. For instance, in one example, the user executes an application on the user's smartphone that syncs and communicates with the air filtration device. The user may then use the application to monitor the status of the air filtration device (such as by viewing one or more of the pre-filter fault indicator, the HEPA filter fault indicator, the air filtration device status indicator, the pre-filter status indicators, the HEPA filter status indicators, and the selected operating mode) remotely, such as from across the room or across the jobsite. Additionally, as described above, in certain embodiments the computing device of the user enables the user to input instructions to control certain aspects of the air filtration device and communicates such instructions to the air filtration device.
3.2 Sensors
The dust sensor 3910 determines the level of dust or impurities in the air surrounding the air filtration device. In this example embodiment, the dust sensor includes an optical dust sensor, such as a Sharp GP2Y1010AU0F optical dust sensor, though any suitable sensor may be employed to detect the level of dust in the air.
The pre-filter differential pressure sensor 3920 measures the differential pressure across the pre-filter. More specifically, the pre-filter differential pressure sensor includes two ports: (1) a first open port; and (2) a second port connected to the pressure sensor port 2170b located between the pre-filter and the HEPA filter (i.e., located downstream of the pre-filter and upstream of the HEPA filter). The pre-filter differential pressure sensor determines the differential pressure across the pre-filter by measuring the pressures at the first and second ports and determining the difference between those pressure measurements.
The HEPA filter differential pressure sensor 3930 measures the differential pressure across the HEPA filter. More specifically, the HEPA filter differential pressure sensor includes two ports: (1) a first port connected to the pressure sensor port 2170b located between the pre-filter and the HEPA filter (i.e., located downstream of the pre-filter and upstream of the HEPA filter); and (2) a second port connected to the pressure sensor port 2170a located between the HEPA filter and the fan assembly (i.e., located downstream of the HEPA filter and upstream of the fan assembly). The HEPA filter differential pressure sensor determines the differential pressure across the HEPA filter by measuring the pressures at the first and second ports and determining the difference between those pressure measurements.
The fan differential pressure sensor 3940 measures the differential pressure across the fan. More specifically, the fan differential pressure sensor includes two ports: (1) a first port connected to the pressure sensor port 2170a located between the HEPA filter and the fan assembly (i.e., located downstream of the HEPA filter and upstream of the fan assembly); and (2) a second port connected to the pressure sensor port 2119 located downstream of the fan assembly. The fan differential pressure sensor determines the differential pressure across the fan by measuring the pressures at the first and second ports and determining the difference between those pressure measurements.
In this embodiment, the differential pressure sensors are Freescale +/−1.45 PSI MPXV7002DP differential pressure sensors, though any suitable differential pressure sensors may be employed.
In other embodiments, rather than employing three differential pressure sensors, the air filtration device includes absolute pressure sensors and determines the appropriate differential pressures using measured absolute pressures. For instance, in one example embodiment, the air filtration device includes: (a) a first absolute pressure sensor including an open port, (b) a second absolute pressure sensor including a port connected to the pressure sensor port located between the pre-filter and the HEPA filter, (c) a third absolute pressure sensor including a port connected to the pressure sensor port located between the HEPA filter and the fan assembly, and (d) a fourth absolute pressure sensor including a port connected to the pressure sensor port located downstream of the fan assembly. In this example embodiment, the air filtration device: (a) determines the differential pressure across the pre-filter by determining the difference between the pressure measurements of the first and second absolute pressure sensors, (b) determines the differential pressure across the HEPA filter by determining the difference between the pressure measurements of the second and third absolute pressure sensors, and (c) determines the differential pressure across the fan by determining the difference between the pressure measurements of the third and fourth absolute pressure sensors.
The fan-speed sensor 3950 measures the speed of the fan 2310, such as the number of revolutions per minute at which the fan 2310 is spinning. In this example embodiment, the fan-speed sensor includes an optical fan-speed sensor, such as an Optek OPB716Z sensor, though any suitable fan-speed sensor may be employed. In another embodiment, the fan assembly includes an integrated fan-speed sensor and communicates the fan speed to the controller. In this embodiment, the air filtration device does not include a separate fan-speed sensor in addition to the integrated fan-speed sensor of the fan assembly.
The pre-filter presence sensor 3960 determines whether an acceptable pre-filter is installed in the air filtration device, as described below with respect to the pre-filter presence detection process 6000. In this example embodiment, the lower housing component supports or otherwise includes a pre-filter presence sensor in the form of a pre-filter limit switch that is actuatable by the pre-filter limit switch actuator of the pre-filter. In another embodiment, the pre-filter presence sensor is a Hall Effect sensor that detects a metallic element included in the pre-filter, as described below. In another embodiment, the pre-filter presence sensor is a radio frequency identification (RFID) reader configured to read or recognize an RFID tag included in the pre-filter, as described below. Any other suitable pre-filter presence sensor may be employed.
The below-described operations and processes may be performed regardless of the shapes of the filters. For instance, the below-described operations and processes may be performed in an air filtration device employing two substantially flat filters or semicircular filters positioned one in front of the other.
4.1 Power-up Process
In this example embodiment, as noted above, the air filtration device includes a power switch 2176 that powers the air filtration device on and off when the air filtration device is connected to a power source (such as an A/C power source). When the air filtration device is connected to a power source and the air filtration device is powered on (i.e., the power switch is switched to “ON”), the air filtration device: (a) displays “CAL” on the hour meter display; (b) lights the LED of the air filtration device status indicator green; (c) lights the green LED of the pre-filter status indicators in a flashing manner; (d) lights the green LED of the HEPA filter status indicators in a flashing manner; and (e) after waiting (if necessary) for the fan speed to fall below 100 revolutions per minute, calibrates the pre-filter differential pressure sensor, the HEPA filter differential pressure sensor, and the fan differential pressure sensor by taking and averaging several pressure measurements.
After calibrating the differential pressure sensors: (a) if the standby operating mode is selected, the air filtration device enters full standby mode (described below); and (b) if the automatic fan speed setting selection operating mode or any of the manual fan speed setting operating modes is selected, the air filtration device enters that selected (non-standby) operating mode.
This is one example of the power-up process. In other embodiments, the power-up process may include different or additional steps and/or may not include certain of the above-described steps.
4.2 Fan Speed Settings
In this example embodiment, the air filtration device is operable at any of a plurality of different fan speed settings including at least a minimum fan speed setting and a maximum fan speed setting. Each fan speed setting corresponds to a different desired air flow rate through the air filtration device. For instance, in this example embodiment, the air filtration device is operable at any of three fan speed settings including: (a) a minimum fan speed setting that corresponds to a first desired air flow rate through the air filtration device, (b) a medium fan speed setting that corresponds to a second desired air flow rate through the air filtration device, and (c) a maximum fan speed setting that corresponds to a third desired rate of air flow through the air filtration device. In this example embodiment, the third desired air flow rate through the air filtration device is 600 cubic feet per minute, which is greater than the second desired air flow rate through the air filtration device, which is 400 cubic feet per minute, which is greater than the first desired air flow rate through the air filtration device, which is 200 cubic feet per minute.
It should be appreciated that, in other embodiments, the air filtration device may be operable at any suitable number of different fan speed settings. It should also be appreciated that the particular air flow rates associated with the different fan speed settings may be any suitable air flow rates.
It should also be appreciated that “current fan speed setting” as used herein refers to the fan speed setting at which the air filtration device is operating at a particular point in time. For instance: (a) at a particular point in time, if one of the manual fan speed setting operating modes (described below) is selected, the current fan speed setting (i.e., the fan speed setting at that particular point in time) is the fan speed setting associated with that selected manual fan speed setting operating mode; and (b) at a particular point in time, if the automatic fan speed setting selection operating mode (described below) is selected, the current fan speed setting (i.e., the fan speed setting at that particular point in time) is the fan speed setting selected by the air filtration device via the automatic fan speed setting selection process (described below).
4.3 Operating Modes
In this example embodiment, the air filtration device includes a plurality of different user-selectable operating modes including a plurality of different manual fan speed setting operating modes, an automatic fan speed setting selection operating mode, and a standby operating mode. As described above, the operating modes are selectable using the operating mode selector.
4.3.1 Manual Fan Speed Setting Operating Modes
In this example embodiment, the air filtration device includes a different user-selectable manual fan speed setting operating mode corresponding to each fan speed setting at which the air filtration device may operate. This enables the user to manually select and set the fan speed setting at which the user desires the air filtration device to operate.
In this example embodiment, the air filtration device includes: (a) a user-selectable manual minimum fan speed setting operating mode that, when selected by the user, sets the fan speed setting to the minimum fan speed setting (which corresponds to the first desired air flow rate through the air filtration device) and causes the air filtration device to operate at the minimum fan speed setting; (b) a user-selectable manual medium fan speed setting operating mode that, when selected by the user, sets the fan speed setting to the medium fan speed setting (which corresponds to the second desired air flow rate through the air filtration device) and causes the air filtration device to operate at the medium fan speed setting; and (c) a user-selectable manual maximum fan speed setting operating mode that, when selected by the user, sets the fan speed setting to the maximum fan speed setting (which corresponds to the third desired air flow rate through the air filtration device) and causes the air filtration device to operate at the maximum fan speed setting.
In this example embodiment, when the air filtration device is operating in either the manual maximum fan speed setting operating mode or the manual medium fan speed setting operating mode such that the fan speed setting is either the maximum fan speed setting or the medium fan speed setting, the air filtration device employs dynamic fan speed control to adjust the fan speed to achieve the desired air flow rate through the air filtration device. Dynamic fan speed control is described in detail below.
On the other hand, in this example embodiment, when the air filtration device is operating in the manual minimum fan speed setting operating mode such that the fan speed setting is the minimum fan speed setting, the air filtration device operates the fan at a substantially constant, designated fan speed. In other words, when the air filtration device is operating in the manual minimum fan speed setting operating mode such that the fan speed setting is the minimum fan speed setting, the air filtration device does not employ dynamic fan speed control in this example embodiment. It should be appreciated, however, that in other embodiments the air filtration device employs dynamic fan speed control when the fan speed setting is the minimum fan speed setting.
In other embodiments, the air filtration device does not include a manual fan speed setting operating mode associated with each fan speed setting at which the air filtration device may operate. For instance, in one example embodiment in which the air filtration device includes five fan speed settings at which the air filtration device may operate, the air filtration device includes manual fan speed setting operating modes associated with a first, third, and fifth fan speed setting and does not include a manual fan speed setting operating mode associated with a second and fourth fan speed setting. In another embodiment, the air filtration device does not include any manual fan speed setting operating modes. In another embodiment, the air filtration device includes a single manual fan speed setting operating mode.
4.3.2 Automatic Fan Speed Setting Selection Operating Mode
In this example embodiment, the air filtration device includes a user-selectable automatic fan speed setting selection operating mode. Generally, when the automatic fan speed setting selection operating mode is selected by the user, the air filtration device uses the dust sensor to measure the amount of dust in the air surrounding the air filtration device and, if necessary, automatically increases or decreases the fan speed setting to account for the amount of dust in the air. Thus, when operating in the automatic fan speed setting selection operating mode, the air filtration device dynamically and automatically adjusts the fan speed setting in real-time to account for varying levels of dust in the air surrounding the air filtration device, which eliminates the need for the user to guess the amount of dust in the air and manually select what the user believes to be the most effective and efficient fan speed setting in which to operate the air filtration device to remove that dust.
More specifically, in this example embodiment, each of the fan speed settings is associated with a different range of dust levels. The range of dust levels associated with a particular fan speed setting includes the dust levels that the air filtration device may most effectively and efficiently manage or clean when operating at that particular fan speed setting. For instance, in this example embodiment: (a) the minimum fan speed setting is associated with a first range of dust levels beginning at zero and ending at a maximum dust level associated with the minimum fan speed setting; (b) the medium fan speed setting is associated with a second range of dust levels beginning at a minimum dust level associated with the medium fan speed setting, which is greater than the maximum dust level associated with the minimum fan speed setting, and ending at a maximum dust level associated with the medium fan speed setting; and (c) the maximum fan speed setting is associated with a third range of dust levels beginning at a minimum dust level associated with the maximum fan speed setting, which is greater than the maximum dust level associated with the medium fan speed setting, and ending at a maximum measurable dust level, which is the highest dust level measurable by the dust sensor.
For instance, Table 1 below includes example ranges of dust levels associated with the minimum, medium, and maximum fan speed settings. In this example, the dust levels range from zero to ten. Each fan speed setting may be associated with any suitable range of dust levels, and that each range of dust levels may include any suitable dust levels.
Thus, in this example: (a) when the measured dust level is 0, 1, 2, or 3, the air filtration device most effectively and efficiently manages or cleans the dust when operating at the minimum fan speed setting; (b) when the measured dust level is 4, 5, or 6, the air filtration device most effectively and efficiently manages or cleans the dust when operating at the medium fan speed setting; and (c) when the measured dust level is 7, 8, 9, or 10, the air filtration device most effectively and efficiently manages or cleans the dust when operating at the maximum fan speed setting.
At each of a plurality of predetermined dust level sensing time intervals, such as every fifteen seconds (or any other suitable length of time), the air filtration device measures the dust level using the dust level sensor and determines whether the range of dust levels associated with the current fan speed setting includes the measured dust level. If the range of dust levels associated with the current fan speed setting includes the measured dust level, the air filtration device maintains the current fan speed setting. If the measured dust level exceeds the range of dust levels associated with the current fan speed setting, the air filtration device increases the fan speed setting. If the measured dust level falls below the range of dust levels associated with the current fan speed setting for a designated number of consecutive dust level sensing time intervals, the air filtration device decreases the fan speed setting.
The automatic fan speed setting selection process 4000 starts when the air filtration device receives a selection of the automatic fan speed setting selection operating mode. The air filtration device sets the fan speed setting to the minimum fan speed setting such that the current fan speed setting is the minimum fan speed setting, as indicated by block 4100. As explained above, each fan speed setting is associated with a different range of dust levels including a minimum dust level and a maximum dust level. The air filtration device sets the variable n equal to zero, as indicated by block 4110. The variable n represents a number of dust level sensing time intervals in which the measured dust level during that particular dust level sensing time interval is less than the minimum dust level in the range of dust levels associated with the current fan speed setting during that particular dust level sensing time interval. The air filtration device measures the dust level using the dust sensor, as indicated by block 4120.
The air filtration device determines if the measured dust level is greater than the maximum dust level in the range of dust levels associated with the current fan speed setting, as indicated by diamond 4130. If the air filtration device determines that the measured dust level is greater than the maximum dust level in the range of dust levels associated with the current fan speed setting, the air filtration device increases the fan speed setting, such as by one level (e.g., from the minimum fan speed setting to the medium fan speed setting or from the medium fan speed setting to the maximum fan speed setting), as indicated by block 4140. The air filtration device determines whether a dust level sensing time interval has elapsed, as indicated by diamond 4150. If the air filtration device determines that the dust level sensing time interval has elapsed, the process 4000 returns to the block 4120. If, on the other hand, the air filtration device determines that the dust level sensing time interval has not elapsed, the air filtration device maintains the current fan speed setting, as indicated by block 4160, and the process 4000 returns to the diamond 4150.
Returning to the diamond 4130, if the air filtration device determines that the measured dust level is not greater than the maximum dust level in the range of dust levels associated with the current fan speed setting, the air filtration device determines if the measured dust level is less than the minimum dust level in the range of dust levels associated with the current fan speed setting, as indicated by diamond 4170. If the air filtration device determines that the measured dust level is not less than the minimum dust level in the range of dust levels associated with the current fan speed setting, the air filtration device sets the variable n equal to zero, and the process 4000 proceeds to the block 4160, described above.
If, on the other hand, the air filtration device determines that the measured dust level is less than the minimum dust level in the range of dust levels associated with the current fan speed setting, the air filtration device sets the variable n equal to n+1, as indicated by block 4190. The air filtration device determines if the variable n is at least equal to a designated number, as indicated by diamond 4200. If the air filtration device determines that the variable n is not at least equal to the designated number, the process 4000 proceeds to the block 4160. If, on the other hand, the air filtration device determines that the variable n is at least equal to the designated number, the air filtration device decreases the fan speed setting, such as by one level (e.g., from the maximum fan speed setting to the medium fan speed setting or from the medium fan speed setting to the minimum fan speed setting), as indicated by block 4220. The air filtration device sets the variable n equal to zero, and the process 4000 proceeds to the diamond 4150.
In this example embodiment, the designated number is four such that the air filtration device decreases the fan speed setting when the air filtration device determines that the measured dust level is less than the minimum dust level in the range of dust levels associated with the current fan speed setting for four consecutive dust level sensing time intervals. It should be appreciated, however, that the designated number may be any suitable number in other embodiments. It should also be appreciated that, in certain embodiments, the designated number is equal to one. Thus, in these embodiments, the air filtration device decreases the fan speed setting when the air filtration device determines that the measured dust level is less than the minimum dust level in the range of dust levels associated with the current fan speed setting.
In the example embodiment described above with respect to
In other embodiments, when operating in the automatic fan speed setting selection operating mode, the air filtration device powers the fan off when the measured dust level is a designated dust level or within a designated range of dust levels. For instance, Table 2 below includes example ranges of dust levels associated with the off, minimum, medium, and maximum fan speed settings. In this example, the dust levels range from zero to ten. Each fan speed setting may be associated with any suitable range of dust levels, and that each range of dust levels may include any suitable dust levels.
Thus, in this example: (a) when the measured dust level is 0, the air filtration device powers the fan off because filtration is not required; (b) when the measured dust level is 1, 2, or 3, the air filtration device most effectively and efficiently manages or cleans the dust when operating at the minimum fan speed setting; (c) when the measured dust level is 4, 5, or 6, the air filtration device most effectively and efficiently manages or cleans the dust when operating at the medium fan speed setting; and (d) when the measured dust level is 7, 8, 9, or 10, the air filtration device most effectively and efficiently manages or cleans the dust when operating at the maximum fan speed setting. Thus, in this example embodiment, when operating in the automatic fan speed setting selection operating mode, the air filtration device only operates fan when the measured dust level is greater than zero (though the threshold minimum dust level that causes operation of the fan may be any suitable dust level).
4.3.3 Standby Operating Mode
In this example embodiment, the air filtration device includes a user-selectable standby operating mode in which the air filtration device is powered on but in which the fan does not operate. If the air filtration device receives a selection of the standby operating mode upon power-up of the air filtration device, the air filtration device lights the LED of the air filtration device status indicator green. If the standby operating mode is selected after the air filtration device has determined the occlusion levels of the filters (described below) and has indicated such occlusion levels by lighting the appropriate pre-filter and HEPA filter status indicators, the air filtration device maintains those filter occlusion level indicators for a designated period, such as 10 seconds (or any other suitable period of time). Once the designated period expires, the air filtration device enters full standby operating mode. Once in full standby operating mode, when the automatic fan speed setting selection operating mode or any of the manual fan speed setting operating modes is selected, the air filtration device performs the filter occlusion level monitoring process (described below).
4.4 Dynamic Fan Speed Control
As noted above, in certain instances, the air filtration device employs dynamic fan speed control to adjust the fan speed to achieve a desired air flow rate through the air filtration device. Generally, when employing dynamic fan speed control, the air filtration device uses the differential pressure across the fan and the desired air flow rate through the air filtration device to determine a desired fan speed that achieves the desired flow rate through the air filtration device. This enables the air filtration device to maintain that desired air flow rate through the air filtration device by varying the fan speed as the pre-filter and the HEPA filter occlude during operation of the air filtration device, which prevents the air flow rate through the air filtration device from falling below the desired air flow rate and impairing the air filtration device's performance.
In this example embodiment, the air filtration device employs dynamic fan speed control when the current fan speed setting is one of at least one designated fan speed setting. Here, the maximum fan speed setting and the medium fan speed setting are designated fan speed settings and, therefore, the air filtration device employs dynamic fan speed control when the air filtration device is operating at either of these fan speed settings. The minimum fan speed setting is not a designated fan speed setting in this example embodiment and, therefore, the air filtration device does not employ dynamic fan speed control when the air filtration device is operating at the minimum fan speed setting. It should be appreciated that, in other embodiments: (a) all of the fan speed settings are designated fan speed settings; (b) a plurality, but less than all, of the fan speed settings are designated fan speed settings; (c) one of the fan speed settings is a designated fan speed setting; (d) none of the fan speed settings are designated fan speed settings; and (e) any particular fan speed setting(s) may be a designated fan speed setting(s).
It should be appreciated that, in this example embodiment, the air filtration device employs dynamic fan speed control when the current fan speed setting is one of the at least one designated fan speed setting regardless of whether the air filtration device is operating in the automatic fan speed setting selection operating mode or in one of the manual fan speed setting operating modes.
The dynamic fan speed control process 5000 starts when the air filtration device begins operating in either the automatic fan speed setting selection operating mode or one of the manual fan speed setting operating modes. The air filtration device determines the current fan speed setting, as indicated by block 5100. As noted above, each fan speed setting is associated with or corresponds to a desired air flow rate through the air filtration device. The air filtration device determines if the current fan speed setting is the minimum fan speed setting, as indicated by diamond 5110. If the air filtration device determines that the current fan speed setting is the minimum fan speed setting, the air filtration device sets the fan speed to a designated fan speed, as indicated by block 5120.
The air filtration device determines if a fan speed determination time interval has elapsed, as indicated by diamond 5180. In this example embodiment, the fan speed determination time interval is 1 second, though any suitable time period may be employed. If the air filtration device determines that the fan speed determination time interval has elapsed, the process 5000 returns to the block 5100. If, on the other hand, the air filtration device determines that the fan speed determination time interval has not elapsed, the air filtration device maintains the current fan speed, as indicated by block 5190, and the process 5000 returns to the diamond 5180.
Returning to the diamond 5110, if the air filtration device determines that the current fan speed setting is not the minimum fan speed setting, the air filtration device determines the differential pressure (such as a pressure drop) across the fan using the fan differential pressure sensor, as indicated by block 5130. The air filtration device determines a desired fan speed based at least in part on the differential pressure across the fan and the desired air flow rate through the air filtration device, as indicated by block 5140. The air filtration device determines if the desired fan speed is greater than a maximum allowable speed of the fan, as indicated by diamond 5150.
If the air filtration device determines that the desired fan speed is greater than the maximum allowable fan speed, the air filtration device sets the fan speed to the maximum allowable fan speed, as indicated by block 5160, and the process 5000 proceeds to the diamond 5180. If, on the other hand, the air filtration device determines that the desired fan speed is not greater than the maximum allowable fan speed, the air filtration device sets the fan speed to the desired fan speed, as indicated by block 5170. The process 5000 proceeds to the diamond 5180.
It should be appreciated that, in this example embodiment, the air filtration device determines the desired fan speed based at least in part on the differential pressure across the fan and the desired air flow rate through the air filtration device and does not (directly) use the pre-filter and HEPA filter occlusion levels (described below) to do so. In other words, in this example embodiment, the air filtration device determines the desired fan speed is independent of and without determining the pre-filer and HEPA filter occlusion levels.
In other embodiments, the air filtration device determines the desired fan speed based, at least in part, on the determined pre-filter and HEPA filter occlusion levels. That is, in these embodiments the determination of the desired fan speed directly depends on the determined pre-filter and HEPA filter occlusion levels.
In another embodiment, the air filtration device determines that a major air filtration device malfunction occurs when the desired fan speed exceeds the maximum fan speed.
4.5 Filter Presence Detection
4.5.1 Pre-Filter Presence Detection
In this example embodiment, the air filtration device determines whether an acceptable pre-filter is installed in the air filtration device using the pre-filter presence sensor, and prevents use of the fan when an acceptable pre-filter is not installed.
The pre-filter presence detection process 6000 starts when the air filtration device receives a selection of one of the manual fan speed setting selection operating modes or the automatic fan speed setting selection operating mode. As described above, in this example embodiment, the lower housing component supports or otherwise includes a pre-filter limit switch that is actuatable by the pre-filter limit switch actuator of the pre-filter. The air filtration device determines whether the pre-filter limit switch is actuated, as indicated by diamond 6100. If the air filtration device determines that the pre-filter limit switch is actuated, the air filtration device determines that an acceptable pre-filter is installed, as indicated by block 6110, and the process 6000 proceeds to diamond 6140, described below. If, on the other hand, the air filtration device determines that the pre-filter limit switch is not actuated, the air filtration device indicates that an acceptable pre-filter is not installed, as indicated by block 6120, and the air filtration device prevents use of the fan, as indicated by block 6130. As indicated by the diamond 6140, once a pre-filter presence detection time interval elapses, the process 6000 returns to the diamond 6100. In this example embodiment, the pre-filter presence detection time interval is 1 second, though any suitable period of time may be employed.
In this example embodiment, the air filtration device indicates that an acceptable pre-filter is not installed by: (a) lighting the red LED of the pre-filter fault indicator, (b) lighting the LED of the air filtration device status indicator red, and (c) outputting the filter fault indicator tone. Any other indications or combinations of indications may be employed instead of or in addition to the above-described indications.
In another embodiment, the air filtration device employs the pre-filter differential pressure sensor to determine whether an acceptable pre-filter is installed. In this embodiment, the air filtration device determines the differential pressure across the pre-filter using the pre-filter differential pressure sensor. The air filtration device determines if the differential pressure across the pre-filter is greater than or equal to a minimum allowable differential pressure across the pre-filter. If the air filtration device determines that the differential pressure across the pre-filter is greater than or equal to the minimum allowable differential pressure across the pre-filter, the air filtration device determines that an acceptable pre-filter is installed. If, on the other hand, the air filtration device determines that the differential pressure across the pre-filter is less than (i.e., not greater than or equal to) the minimum allowable differential pressure across the pre-filter, the air filtration device indicates that an acceptable pre-filter is not installed, and the air filtration device prevents use of the fan.
In another embodiment, the upper and lower edges of the pre-filter each include an integrated metallic element (such as a 0.003 inch thick×1 inch high element) that substantially spans the pre-filter's circumference. In this embodiment, the pre-filter presence sensor is a Hall Effect sensor that detects the metallic element. In this embodiment, if the Hall Effect sensor does not detect any metallic element, the air filtration device determines that an acceptable pre-filter is not installed and prevents use of the fan, and if the Hall Effect sensor detects a metallic element, the air filtration device determines that an acceptable pre-filter is installed.
In another embodiment, the pre-filter includes at least one RFID tag. In this embodiment, the pre-filter presence sensor is an RFID reader configured to read or recognize the RFID tag included in the pre-filter. In this embodiment, if the RFID reader does not read or recognize an RFID tag or reads or recognizes an improper RFID tag, the air filtration device determines that an acceptable pre-filter is not installed, and if the RFID reader reads or recognizes a proper RFID tag, the air filtration device determines that an acceptable pre-filter is installed. Any other suitable pre-filter presence detection process may be employed.
4.5.2 HEPA Filter Presence Detection
In this example embodiment, the air filtration device determines whether an acceptable HEPA filter is installed in the air filtration device using the differential pressure across the HEPA filter, and prevents use of the fan when an acceptable HEPA filter is not installed.
The HEPA filter presence detection process 7000 starts when the air filtration device receives a selection of one of the manual fan speed setting selection operating modes or the automatic fan speed setting selection operating mode. The air filtration device determines the differential pressure (such as a pressure drop) across the HEPA filter using the HEPA filter differential pressure sensor, as indicated by block 7100. The air filtration device determines if the differential pressure across the HEPA filter is greater than or equal to a minimum allowable differential pressure across the HEPA filter, as indicated by diamond 7110. If the air filtration device determines that the differential pressure across the HEPA filter is greater than or equal to the minimum allowable differential pressure across the HEPA filter, the air filtration device determines that an acceptable HEPA filter is installed, as indicated by block 7120, and the process 7000 proceeds to diamond 7150, described below.
If, on the other hand, the air filtration device determines that the differential pressure across the HEPA filter is less than (i.e., not greater than or equal to) the minimum allowable differential pressure across the HEPA filter, the air filtration device indicates that an acceptable HEPA filter is not installed, as indicated by block 7130, and the air filtration device prevents use of the fan, as indicated by block 7140. As indicated by the diamond 7150, once a HEPA filter presence detection time interval elapses, the process 7000 returns to the block 7100.
In this example embodiment, the HEPA filter presence detection time interval is 1 hour, though any suitable period of time may be employed. Additionally, in this example embodiment, the minimum allowable differential pressure across the HEPA filter is equal to the differential pressure across 0.10 inches of water at a fan speed of 3,000 revolutions per minute, though any suitable minimum allowable differential pressure across the HEPA filter may be employed.
In this example embodiment, the air filtration device indicates that an acceptable HEPA filter is not installed by: (a) lighting the red LED of the HEPA filter fault indicator, (b) lighting the LED of the air filtration device status indicator red, and (c) outputting the filter fault indicator tone. Any other indications or combinations of indications may be employed instead of or in addition to the above-described indications.
In another embodiment, the HEPA filter includes one or more integrated hollow pressure tubes positioned vertically among the pleats of the HEPA filter media. An end of each of these pressure tubes is flush with the bottom of the lower HEPA filter end cap. In this embodiment, the air filtration device includes one or more pressure sensors configured to detect the presence of the pressure tubes. Thus, in this embodiment, if a HEPA filter without such pressure tubes is installed, the air filtration device will determine that an improper HEPA filter is installed, and will not operate.
In another embodiment, the HEPA filter includes at least one RFID tag. In this embodiment, the air filtration device includes a HEPA filter presence sensor in the form of an RFID reader configured to read or recognize the RFID tag included in the HEPA filter. In this embodiment, if the RFID reader does not read or recognize an RFID tag or reads or recognizes an improper RFID tag, the air filtration device determines that an acceptable HEPA filter is not installed, and if the RFID reader reads or recognizes a proper RFID tag, the air filtration device determines that an acceptable HEPA filter is installed. Any other suitable HEPA filter presence detection process may be employed.
As described below, in certain embodiments, the HEPA filter presence detection process is part of the filter occlusion level monitoring process.
4.6 Filter Occlusion Level Monitoring
In this example embodiment, the air filtration device monitors the occlusion levels of the pre-filter and the HEPA filter (i.e., the cleanliness levels of the pre-filter and the HEPA filter) and provides feedback regarding the filter occlusion levels to the user to enable the user to quickly and easily determine how clean (or dirty, blocked, or clogged) the pre-filter and the HEPA filter are. When the pre-filter occlusion level exceeds a pre-filter shutdown threshold, the HEPA filter occlusion level exceeds a HEPA filter shutdown threshold, or both, the air filtration device enters a shutdown mode in which the air filtration device eventually prevents any use of the fan until the appropriate filter(s) is(are) replaced. This ensures that the air filtration device does not operate for an extended period of time with a pre-filter and/or a HEPA filter so occluded as to inhibit effective and efficient operation of the air filtration device.
The filter occlusion level monitoring process 8000 starts after (such as a designated period of time after (such as 10 seconds or any other suitable time period)) the air filtration device receives a selection of the automatic fan speed setting selection operating mode or any of the manual fan speed setting operating modes either upon power-up of the air filtration device or when the air filtration device is in the full standby mode (described above). The air filtration device increases the fan speed to a differential pressure determination fan speed, such as 3,000 revolutions per minute or any other suitable fan speed, as indicated by block 8105. The air filtration device determines the differential pressure (such as a pressure drop) across the pre-filter using the pre-filter differential pressure sensor, as indicated by block 8100, and the differential pressure (such as a pressure drop) across the HEPA filter using the HEPA filter differential pressure sensor, as indicated by block 8110.
The air filtration device determines the pre-filter occlusion level based, at least in part, on the determined differential pressure across the pre-filter and the determined differential pressure across the HEPA filter, as indicated by block 8120. The air filtration device also determines the HEPA filter occlusion level based, at least in part, on the on the determined differential pressure across the pre-filter and the determined differential pressure across the HEPA filter, as indicated by block 8160. In this example embodiment, while determining the filter occlusion levels (which includes determining the differential pressures across the pre-filter and the HEPA filter), the air filtration device: (a) lights the yellow LED of the pre-filter status indicators in a blinking or flashing manner; (b) lights the yellow LED of the HEPA filter status indicators in a blinking or flashing manner; and (c) displays “tESt” in the hour meter display. This enables the user to quickly and easily determine when the air filtration device is measuring the filter occlusion levels. Any other indications or combinations of indications may be employed instead of or in addition to the above-described indications.
The air filtration device determines if the determined pre-filter occlusion level exceeds a pre-filter shutdown threshold, as indicated by diamond 8130. The pre-filter shutdown threshold is a maximum allowable pre-filter occlusion level. Once the pre-filter occlusion level reaches the pre-filter shutdown threshold, the air filtration device may no longer efficiently and effectively clean the air (until the pre-filter is replaced). If the air filtration device determines that the determined pre-filter occlusion level exceeds the pre-filter shutdown threshold, the process 8000 proceeds to diamond 8200, described below.
If, on the other hand, the air filtration device determines that the determined pre-filter occlusion level does not exceed the pre-filter shutdown threshold, the air filtration device determines which of a plurality of different pre-filter occlusion level ranges includes the determined pre-filter occlusion level, as indicated by block 8140. In this example embodiment, each pre-filter occlusion level range is associated with a general indicator of the cleanliness of the pre-filter. For instance, in this example embodiment, the pre-filter occlusion level ranges include: (a) a first or Clean pre-filter occlusion level range, (b) a second or Slightly Occluded pre-filter occlusion level range, and (c) a third or Highly Occluded pre-filter occlusion level range. In this example embodiment, each occlusion level included in the Slightly Occluded pre-filter occlusion level range is greater than each occlusion level included in the Clean pre-filter occlusion level range, and each occlusion level included in the Highly Occluded pre-filter occlusion level range is greater than each occlusion level included in the Slightly Occluded pre-filter occlusion level range. The maximum occlusion level in the Highly Occluded pre-filter occlusion level range is the pre-filter shutdown threshold. For instance, Table 3 below includes example ranges of occlusion levels associated with the Clean, Slightly Occluded, and Highly Occluded pre-filter occlusion level ranges. In this example, the occlusion levels range from zero to ten. Each cleanliness indicator may be associated with any suitable range of pre-filter occlusion levels, and that each range of pre-filter occlusion levels may include any suitable pre-filter occlusion levels.
Example Pre-Filter Occlusion Level Ranges
Returning to the process 8000, the air filtration device indicates the pre-filter occlusion level range that includes the determined pre-filter occlusion level, as indicated by block 8150. In this example embodiment, the air filtration device does so by: (a) if the Clean pre-filter occlusion level range includes the determined pre-filter occlusion level, lighting the green LED of the pre-filter status indicators; (b) if the Slightly Occluded pre-filter occlusion level range includes the determined pre-filter occlusion level, lighting the yellow LED of the pre-filter status indicators; and (c) if the Highly Occluded pre-filter occlusion level range includes the determined pre-filter occlusion level, lighting the red LED of the pre-filter status indicators. This enables a user to quickly and easily determine how clean (or dirty) the pre-filter is. The process 8000 proceeds to the diamond 8200.
Turning to diamond 8170, the air filtration device determines if the determined HEPA filter occlusion level exceeds a HEPA filter shutdown threshold. The HEPA filter shutdown threshold is a maximum allowable HEPA filter occlusion level. Once the HEPA filter occlusion level reaches the HEPA filter shutdown threshold, the air filtration device may no longer efficiently and effectively clean the air (until the HEPA filter is replaced). If the air filtration device determines that the determined HEPA filter occlusion level exceeds the HEPA filter shutdown threshold, the process 8000 proceeds to the diamond 8200, described below
If, on the other hand, the air filtration device determines that the determined HEPA filter occlusion level does not exceed the HEPA filter shutdown threshold, the air filtration device determines which of a plurality of different HEPA filter occlusion level ranges includes the determined HEPA filter occlusion level, as indicated by block 8180. In this example embodiment, each HEPA filter occlusion level range is associated with a general indicator of the cleanliness of the HEPA filter. For instance, in this example embodiment, the HEPA filter occlusion level ranges include: (a) a first or Clean HEPA filter occlusion level range, (b) a second or Slightly Occluded HEPA filter occlusion level range, and (c) a third or Highly Occluded HEPA filter occlusion level range. In this example embodiment, each occlusion level included in the Slightly Occluded HEPA filter occlusion level range is greater than each occlusion level included in the Clean HEPA filter occlusion level range, and each occlusion level included in the Highly Occluded HEPA filter occlusion level range is greater than each occlusion level included in the Slightly Occluded HEPA filter occlusion level range. The maximum occlusion level in the Highly Occluded HEPA filter occlusion level range is the HEPA filter shutdown threshold. For instance, Table 4 below includes example ranges of occlusion levels associated with the Clean, Slightly Occluded, and Highly Occluded HEPA filter occlusion level ranges. In this example, the occlusion levels range from zero to ten. Each cleanliness indicator may be associated with any suitable range of HEPA filter occlusion levels, and that each range of HEPA filter occlusion levels may include any suitable HEPA filter occlusion levels.
Example HEPA filter Occlusion Level Ranges
Returning to the process 8000, the air filtration device indicates the HEPA filter occlusion level range that includes the determined HEPA filter occlusion level, as indicated by block 8190. In this example embodiment, the air filtration device does so by: (a) if the Clean HEPA filter occlusion level range includes the determined HEPA filter occlusion level, lighting the green LED of the HEPA filter status indicators; (b) if the Slightly Occluded HEPA filter occlusion level range includes the determined HEPA filter occlusion level, lighting the yellow LED of the HEPA filter status indicators; and (c) if the Highly Occluded HEPA filter occlusion level range includes the determined HEPA filter occlusion level, lighting the red LED of the HEPA filter status indicators. This enables a user to quickly and easily determine how clean (or dirty) the HEPA filter is. The process 8000 proceeds to the diamond 8200.
Turning to the diamond 8200, the air filtration device determines if: (a) the determined pre-filter occlusion level exceeds the pre-filter shutdown threshold, and/or (b) the determined HEPA filter occlusion level exceeds the HEPA filter shutdown threshold. If neither: (a) the determined pre-filter occlusion level exceeds the pre-filter shutdown threshold, nor (b) the determined HEPA filter occlusion level exceeds the HEPA filter shutdown threshold, as indicated by diamond 8210, once a filter occlusion level determination time interval elapses, the process 8000 returns to the block 8100. In this example embodiment, the filter occlusion level determination time interval is 60 minutes, though any suitable period of time may be employed.
If, on the other hand, at least one of: (a) the determined pre-filter occlusion level exceeds the pre-filter shutdown threshold, and (b) the determined HEPA filter occlusion level exceeds the HEPA filter shutdown threshold, the air filtration device indicates that the pre-filter, the HEPA filter, or both need replacement, as indicated by block 8220. More specifically: (a) if the determined pre-filter occlusion level exceeds the pre-filter shutdown threshold, the air filtration device indicates that the pre-filter needs replacement; (b) if the determined HEPA filter occlusion level exceeds the HEPA filter shutdown threshold, the air filtration device indicates that the HEPA filter needs replacement; and (c) if the determined pre-filter occlusion level exceeds the pre-filter shutdown threshold and the determined HEPA filter occlusion level exceeds the HEPA filter shutdown threshold, the air filtration device indicates that both the pre-filter and the HEPA filter need replacement. The air filtration device enters the shutdown mode, as indicated by block 8230, and initiates a designated shutdown time period, as indicated by block 8240. In this example embodiment, the designated shutdown time period is 4 hours, though the designated shutdown time period may be any suitable time period.
The air filtration device determines if it is operating in the automatic fan speed setting selection operating mode or the manual maximum fan speed setting operating mode, as indicated by diamond 8250. If the air filtration device is not operating in either the automatic fan speed setting selection operating mode or the manual maximum fan speed setting operating mode, the process 8000 proceeds to block 8270, described below. If, on the other hand, the air filtration device is operating in the automatic fan speed setting selection operating mode or the manual maximum fan speed setting operating mode, the air filtration device powers down the fan, as indicated by block 8260.
The air filtration device prevents use of the automatic fan speed setting selection operating mode and prevents use of the manual maximum fan speed setting operating mode, as indicated by the block 8270. The air filtration device enables operation of the air filtration device in either the manual medium fan speed setting operating mode or the manual minimum fan speed setting operating mode, as indicated by block 8280. The air filtration device determines if the designated shutdown time period has expired, as indicated by diamond 8290. If the air filtration device determines that the designated shutdown time period has not expired, the process 8000 returns to the block 8280. If, on the other hand, the air filtration device determines that the designated shutdown time period has expired, the air filtration device powers down the fan, as indicated by block 8300, and prevents use of the fan, as indicated by block 8310. In other words, once the designated shutdown time period expires, the air filtration device prevents use of the automatic fan speed setting selection operating mode and any of the manual fan speed setting operating modes.
In this example embodiment, the air filtration device indicates that the pre-filter, the HEPA filter, or both need replacement in a variety of different manners. More specifically, in this example embodiment, if the pre-filter occlusion level exceeds the pre-filter shutdown threshold and the air filtration device is operating in the automatic fan speed setting selection operating mode or the manual maximum fan speed setting operating mode, the air filtration device indicates that the pre-filter needs replacement by: (a) lighting the red LED of the pre-filter status indicators in a flashing or blinking manner, (b) lighting the red LED of the pre-filter fault indicator, (c) lighting the LED of the air filtration device status indicator red, and (d) outputting the filter change alarm tone. In this example embodiment, if the pre-filter occlusion level exceeds the pre-filter shutdown threshold and the air filtration device is operating in the manual medium fan speed setting operating mode or the manual minimum fan speed setting mode, the air filtration device indicates that the pre-filter needs replacement by: (a) lighting the red LED of the pre-filter status indicators in a flashing or blinking manner, (b) lighting the red LED of the pre-filter fault indicator, and (c) lighting the LED of the air filtration device status indicator green or keeping the LED of the air filtration device status indicator lit green. When the designated shutdown time period expires, the air filtration device: (a) lights the LED of the air filtration device status indicator red, and (b) outputs the filter change alarm tone while maintaining flashing the red pre-filter status indicator and lighting the red LED of the pre-filter fault indicator.
In this example embodiment, if the HEPA filter occlusion level exceeds the HEPA filter shutdown threshold and the air filtration device is operating in the automatic fan speed setting selection operating mode or the manual maximum fan speed setting operating mode, the air filtration device indicates that the HEPA filter needs replacement by: (a) lighting the red LED of the HEPA filter status indicators in a flashing or blinking manner, (b) lighting the red LED of the HEPA filter fault indicator, (c) lighting the LED of the air filtration device status indicator red, and (d) outputting the filter change alarm tone. In this example embodiment, if the HEPA filter occlusion level exceeds the HEPA filter shutdown threshold and the air filtration device is operating in the manual medium fan speed setting operating mode or the manual minimum fan speed setting mode, the air filtration device indicates that the HEPA filter needs replacement by: (a) lighting the red LED of the HEPA filter status indicators in a flashing or blinking manner, (b) lighting the red LED of the HEPA filter fault indicator, and (c) lighting the LED of the air filtration device status indicator green or keeping the LED of the air filtration device status indicator lit green. When the designated shutdown time period expires, the air filtration device: (a) lights the LED of the air filtration device status indicator red, and (b) outputs the filter change alarm tone while maintaining flashing the red HEPA filter status indicator and lighting the red LED of the HEPA filter fault indicator.
In this example embodiment, if the air filtration device receives an input to switch to the standby mode while the air filtration device is determining the pre-filter and HEPA filter occlusion levels, the air filtration device stops such determinations and shuts the fan down. The air filtration device restarts the filter occlusion level monitoring process once the air filtration device receives an input to switch from the standby mode into the automatic fan speed setting selection operating mode or any of the manual fan speed setting operating modes.
Further, in this example embodiment, if the air filtration device receives an input to switch from one of: (a) the automatic fan speed setting selection operating mode, and (b) one of the manual fan speed setting operating modes to another one of: (a) the automatic fan speed setting selection operating mode, and (b) one of the manual fan speed setting operating modes while the air filtration device is determining the pre-filter and HEPA filter occlusion levels, the air filtration device ignores this input until the determinations are complete. For instance, if the air filtration device receives an input to switch the air filtration device from the manual medium fan speed setting operating mode to the manual maximum fan speed setting operating mode while the air filtration device is determining the pre-filter and HEPA filter occlusion levels, the air filtration device does not switch from the manual medium fan speed setting operating mode to the manual maximum fan speed setting operating mode until such determinations are complete.
In another embodiment, the air filtration device prevents use of the fan once at least one of: (a) the determined pre-filter occlusion level exceeds the pre-filter shut down threshold, and (b) the determined HEPA filter occlusion level exceeds the HEPA filter shut down threshold. That is, in this embodiment, the air filtration device does not enable operation at any of the fan speed settings once the air filtration device determines that at least one of the filters needs replacement.
As noted above, in certain embodiments, the HEPA filter presence detection process is part of the filter occlusion level monitoring process. For instance, in one example embodiment, after determining the differential pressure across the HEPA filter using the HEPA filter differential pressure sensor (such as indicated by block 8110 of
4.7 Eliminating Fan-Speed Sensor Error
In various embodiments, the air filtration device—and particularly the controller 3650—ensures the fan 2310 operates at a desired fan speed by using a proportional-integral-derivative (PID) control module. The PID control module determines how much electrical current is supplied to the fan motor. The amount of electrical current supplied to the fan motor controls the fan speed.
The controller 3650 provides two inputs to the PID control module: (1) the desired fan speed, determined as described above; and (2) a measured fan speed. The controller 3650 determines the measured fan speed by: (1) determining ΔT, which approximates the time it takes the fan blade of the fan to make one complete revolution (based on the output of a fan-speed sensor 3950), as described below; and (2) inverting ΔT (i.e., calculating 1/ΔT), which provides the measured fan speed in units of revolutions per unit of time of ΔT (e.g., minutes, seconds, etc.).
The PID control module assumes that the measured fan speed is equal or generally equal to the actual fan speed at the time the controller determines ΔT. The PID control module then determines whether the measured fan speed matches the desired fan speed. If not, the PID control module determines how to vary the electrical current supplied to the fan motor to correct the error, and the controller 3650 does so. For instance, if the measured fan speed is less than the desired fan speed, the PID control module determines to increase the electrical current supplied to the fan motor to cause the fan to spin faster and attain the desired fan speed. But if the measured fan speed is greater than the desired fan speed, the PID control module determines to decrease the electrical current supplied to the fan motor to cause the fan to spin slower and attain the desired fan speed.
As noted above, the controller 3650 determines ΔT based on the output of the fan-speed sensor 3950.
The controller 3650 operates a fan-speed sensor error elimination process to ensure that the controller does not send measured fan speeds determined based on ΔT's that represent the time it takes the fan blade to complete fractions of a revolution to the PID control module. In certain embodiments, the fan-speed sensor error elimination process to ensure that the controller does not send measured fan speeds determined based on ΔT's that represent the time it takes the fan blade to complete multiple revolutions to the PID control module. This ensures the PID control module accurately controls electrical current supplied to the fan motor. Additionally, in certain embodiments, the fan-speed sensor error elimination process ensures the controller doesn't send measured fan speeds based on ΔT's to the PID control module until the measured fan speed is within a designated range of the desired fan speed. This prevents unnecessarily employing the PID control module.
The fan-speed sensor error elimination process 9100 starts when the air filtration device begins operation at a desired fan speed. The controller starts a free-running timer, as block 9110 indicates. The controller monitors for a trip of the fan-speed sensor following the start of the free-running timer, as diamond 9115 indicates. Once the fan-speed sensor is tripped, the controller reads the free-running timer, as block 9120 indicates. (In certain embodiments, following the first trip of the fan-speed sensor the controller resets the timer but does not proceed to block 9120 until another trip of the fan-speed sensor occurs.) The free-running-timer reading is ΔT.
The controller then determines whether ΔT is less than ΔTMIN, as diamond 9125 indicates. ΔTMIN is a set value that is less than the time it takes the fan blade to complete a single revolution at the maximum fan speed setting. If at diamond 9125 the controller determines that ΔT is less than ΔTMIN, the controller does not input a measured fan speed determined based on ΔT to the PID control module, as block 9130 indicates. The process 9100 then returns to diamond 9115. In this scenario in which ΔT is less than ΔTMIN, the fan-speed sensor has tripped before the fan blade has completed a full revolution following the previous fan-speed sensor trip. The controller 3650 is thus configured to filter out these small ΔT's and not use them to calculate measured fan speeds to send to the PID control module.
If, on the other hand, the controller determines at diamond 9125 that ΔT is greater than or equal to ΔTMIN, the controller determines whether ΔT is greater than ΔTMAX, as diamond 9135 indicates. ΔTMAX is a set value that is greater than the time it takes the fan blade to complete a single revolution at the minimum fan speed setting. If at diamond 9135 the controller determines that ΔT is greater than ΔTMAX, the controller resets the free-running timer, as block 9140 indicates, but does not does not input a measured fan speed determined based on ΔT to the PID control module, as block 9130 indicates. The process 9100 then returns to diamond 9115. In this instance, either: (1) the controller is still running up the fan to the desired fan speed; or (2) the fan-speed sensor did not trip following a full revolution of the fan blade. In either case, the controller prevents unnecessary invocation of the PID control module. The controller 3650 is thus configured to filter out these large ΔT's and not use them to calculate measured fan speeds to send to the PID control module.
If, on the other hand, the controller determines at diamond 9135 that ΔT is less than or equal ΔTMAX, the controller determines the measured fan speed based on ΔT, as block 9145 indicates, and inputs the measured fan speed to the PID control module, as block 9150 indicates. The PID control module compares the measured fan speed to the desired fan speed to determine whether to vary the amount of electrical current sent to the fan motor. The controller then resets the free-running timer, as block 9155 indicates, and the process 9100 then returns to diamond 9115. The process 9100 ends when the fan motor is powered off.
This fan-speed sensor error elimination routine solves the three above-described problems that occur when assuming an ideal scenario.
First, ignoring ΔT when ΔT<ΔTMIN ensures the controller will not send impossibly large measured fan speeds (calculated using impossibly small ΔT's) to the PID control module. The fan-speed sensor error elimination process thus filters out ΔT's that are too small to represent the time elapsed during one full revolution of the fan blade. By not sending measured fan speeds calculated using these ΔT's to the PID control module, the controller prevents the inaccurate, non-ideal fan operation that would otherwise follow.
Second, ignoring ΔT when ΔT>ΔTMAX ensures the controller will not send an unreasonably small measured fan speed (calculated using an unreasonably large ΔT) to the PID control module. The fan-speed sensor error elimination process thus filters out ΔT's that are too large to represent the time elapsed during one full revolution of the fan blade. By not sending these ΔT's to the PID control module, the controller prevents the inaccurate, non-ideal fan operation that would otherwise follow.
Third, ignoring ΔT when ΔT>ΔTMAX ensures the controller will not send a measured fan speed (based on ΔT) to the PID control module while the fan is running up to the desired fan speed after a user powers the air filtration device on. The controller therefore prevents unnecessary invocation of the PID control module.
The fan-speed sensor error elimination process 9200 starts when the air filtration device begins operation at a desired fan speed. The controller starts a free-running timer, as block 9210 indicates. At this point, the controller operates two subroutines in parallel: (1) it monitors for a trip of the fan-speed sensor following the start of the free-running timer, as diamond 9215 indicates; and (2) it monitors for the free-running timer reaching a counter-increment threshold, as diamond 9220 indicates. The counter-increment threshold in this example embodiment represents about 1.9 seconds, which is the maximum capacity (or over-run) of the 8-bit free-running timer. In other embodiments, the counter-increment threshold may also be set at a desired threshold beneath the maximum capacity of the free-running timer. For instance, if the free-running timer is a 16-bit or a 32-bit timer, the counter-increment threshold could be set at about 1.9 seconds so the timer signals the controller when it reaches about 1.9 seconds (which is less than the maximum capacity of a 16-bit or a 32-bit timer).
Once the fan-speed sensor is tripped, the controller reads the free-running timer, as block 9225 indicates. (In certain embodiments, following the first trip of the fan-speed sensor the controller resets the timer but does not proceed to block 9225 until another trip of the fan-speed sensor occurs.) The free-running-timer reading is ΔT.
The controller resets a counter (described below), as block 9230 indicates, and determines whether ΔT is less than ΔTMIN, as diamond 9235 indicates. ΔTMIN is a set value that is less than the time it takes the fan blade to complete a single revolution at the maximum fan speed setting. If at diamond 9235 the controller determines that ΔT is less than ΔTMIN, the controller does not input a measured fan speed determined based on ΔT to the PID control module, as block 9240 indicates. The process 9200 then returns to diamond 9215. In this scenario in which ΔT is less than ΔTMIN, the fan-speed sensor has tripped before the fan blade has completed a full revolution following the previous fan-speed sensor trip. The controller 3650 is thus configured to filter out these small ΔT's and not use them to calculate measured fan speeds to send to the PID control module.
If, on the other hand, the controller determines at diamond 9235 that ΔT is greater than or equal to ΔTMIN, the controller determines the measured fan speed based on ΔT, as block 9245 indicates, and inputs the measured fan speed to the PID control module, as block 9250 indicates. The PID control module compares the measured fan speed to the desired fan speed to determine whether to vary the amount of electrical current sent to the fan motor. The controller then resets the free-running timer, as block 9255 indicates, and the process 9100 then returns to diamond 9215.
Returning to diamond 9220, if the controller determines at diamond 9220 that the free-running timer reached the counter-increment threshold, the controller increments the counter, as block 9260 indicates. The counter starts at zero when the process 9200 begins (though it may start at any suitable number). The controller then determines at diamond 9265 whether that incrementing of the counter caused the counter to reach a first quantity (such as three or any suitable quantity), as diamond 9265 indicates.
If the controller determines at diamond 9265 that the incrementing of the counter caused the counter to reach the first quantity (i.e., if the controller determines that a max current condition occurs), the controller inputs a measured fan speed of 0 RPMs (or any other suitable low speed) to the PID control module, as block 9270 indicates. In this scenario, the controller has determined that the fan is either stuck or rotating extremely slowly, and inputting this small fan speed to the PID control module will cause the PID control module to dramatically increase (e.g., maximize or substantially maximize) the electrical current to the fan motor to attempt to free the fan blade. The controller then resets the free-running timer, as block 9275 indicates (or the free-running timer resets itself following overload).
If, on the other hand, the controller determines at diamond 9265 that the incrementing of the counter did not cause the counter to reach the first quantity, the controller determines whether that incrementing of the counter caused the counter to reach a second quantity larger than the first quantity (such as six or any suitable quantity), as diamond 9280 indicates.
If the controller determines at diamond 9280 that the incrementing of the counter caused the counter to reach the second quantity (i.e., if the controller determines that a shut-down condition occurs), the controller shuts down the fan, as block 9285 indicates. In this scenario, the controller determines that there is a problem with the fan that requires maintenance. If, on the other hand, the controller determines at diamond 9280 that the incrementing of the counter did not cause the overload counter to reach the second quantity, the controller resets the free-running timer, as block 9275 indicates (or the free-running timer resets itself following overload).
Ignoring ΔT when ΔT<ΔTMIN ensures the controller will not send impossibly large measured fan speeds (calculated using impossibly small ΔT's) to the PID control module. The fan-speed sensor error elimination process thus filters out ΔT's that are too small to represent the time elapsed during one full revolution of the fan blade. By not sending measured fan speeds calculated using these ΔT's to the PID control module, the controller prevents the inaccurate, non-ideal fan operation that would otherwise follow.
In certain embodiments, ΔTMIN is equal to the time it takes the fan blade to rotate 30 degrees at the highest available fan speed.
In certain embodiments, ΔTMAX is equal to the time it takes the fan blade to rotate 360 degrees at the lowest available fan speed.
In the above-described embodiments, the free-running timer resets in certain scenarios such that each free-running timer reading represents ΔT. In other embodiments, the free-running timer does not overload and runs in perpetuity (until the fan motor is shut down or the air filtration device is powered off). In these embodiments, the controller is configured to store certain free-running timer readings and determine ΔT by calculating the difference between consecutive stored free-running-timer readings. In these embodiments, the controller does not store free-running timer readings that would cause ΔT to be less than ΔTMIN following a fan speed sensor trip. For instance, if the fan speed sensor trips at T1 and again at T2, the controller would determine ΔT=T2−T1. If ΔT<ΔTMIN, the controller would not store T2 and would again monitor for a trip of the fan speed sensor. If ΔT>ΔTMIN, the controller would store T2.
In another embodiment, the process described with respect to
4.8 Air Filtration Device Malfunctions
In this example embodiment, the air filtration device monitors for a plurality of different major air filtration device malfunctions, such as (but not limited to): (a) a locked fan motor; (b) disconnected differential pressure sensor tubes; (c) disconnected electronic components (e.g., the fan, the operating mode selector, and the like); and (d) an electronics failure (e.g., an hour meter display failure or a pre-filter status indicator failure). In this example embodiment, if the air filtration device determines that one of the major air filtration device malfunctions occurs, the air filtration device: (a) powers down the fan, (b) lights the LED of the air filtration device status indicator red, and (c) outputs the audible major air filtration device malfunction tone.
In this example embodiment, the air filtration device also monitors for dust sensor failure. If the air filtration device determines that the dust sensor fails, the air filtration device: (a) enables operation of the air filtration device in any of the manual fan speed setting operating modes; and (b) if the automatic fan speed setting selection operating mode is selected, indicates that a major air filtration device malfunctions occurs, as described above.
It should be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present disclosure, and it should be understood that this application is to be limited only by the scope of the appended claims.