Patent Application
20130186440
The present subject matter relates generally to appliances and related methods that use a turbidity sensor to determine a time interval for liquid entering and/or exiting the appliances.
With continued pressure on natural resources, appliance manufacturers have focused on efficiency in implementing new designs. Accordingly, appliance manufacturers have scrutinized the amount of electricity, the amount of detergent, and the amount of water used by their appliances because these are all important factors in providing efficient and environmentally sensitive machines. In particular, one approach for improving efficiency involves controlling and/or monitoring the amount of water used in various cycles of the appliances.
In order to accurately determine the amount of liquid (e.g., water) used during various cycles, a dishwasher appliance can rely on a predetermined estimate of the rate at which liquid enters and/or exits the appliance—i.e., the appliance's fluid fill rate and fluid drain rate. The dishwasher appliance can utilize such predetermined fluid fill and drain rates to estimate the amount of liquid in the appliance. For example, the dishwasher may permit liquid to flow into the appliance for a predetermined amount of time in order to fill the appliance with a particular volume of liquid (the time being chosen based upon the predetermined fluid fill and drain rates).
However, variations in consumers' water valves, drain pumps, plumbed inlet flow rate, plumbed inlet pressure, and/or certain geometric constraints can cause significant variation in the actual fill and drain rates between appliances. Thus, the actual fill and drain rates can be significantly different (e.g., greater or less) than the predetermined estimate of the appliance's fill and drain rates. Because the actual fill and drain rates can vary between appliances, the predetermined estimate of the appliance's fill and drain rates are generally very conservative and are often chosen such that the appliance overfills with liquid in order to ensure an adequate amount of liquid is provided to the appliance during operation. Such overfill can result in excessive and unnecessary water usage.
Previously, to avoid relying on predetermined estimated fill and drain rates, a flow meter has been used to measure the actual amount of liquid entering and/or exiting the appliance and, in turn, calculate actual fill and drain rates. However, such flow meters can add to the overall cost of producing the appliance. Also, flow meters can require calibration in order to accurately measure the amount of water entering and/or exiting the appliance. Calibrations can be time consuming and inconvenient. Further, flow meters can malfunction and require repair in order to function properly.
Accordingly, an appliance that determines the amount of liquid in the appliance would be useful. Also, an appliance that determines the amount of liquid in the appliance without relying on predetermined estimated fill and drain rates would be useful. In addition, an appliance that determines the amount of liquid in the appliance without relying on a flow meter would be useful. An appliance that can determine the amount of liquid in the appliance without requiring additional measuring devices would be particularly useful.
Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
In a first embodiment, a dishwasher appliance is provided with a cabinet that defines a wash chamber. The cabinet includes a sump positioned adjacent a bottom of the cabinet. The sump is configured for collecting liquid in the wash chamber. A rack assembly is slidably received into the wash chamber and configured for receipt of articles for cleaning. A spray arm assembly is also provided for applying the liquid to the articles in the rack assembly. An inlet is also provided that is configured for selectively adding liquid to the wash chamber of the cabinet. A turbidity sensor is disposed within the sump of the cabinet and configured for measuring a turbidity of fluid in the sump. A processing device is in communication with the inlet and the turbidity sensor. The processing device is configured for adjusting the inlet in order to initiate the flow of liquid into the wash chamber of the cabinet, noting a first time, t1, that corresponds to the step of adjusting, detecting liquid with the turbidity sensor, logging a second time, t2, that corresponds to the step of detecting, and determining a time interval based at least in part on t1 and t2.
In a second embodiment, a method for operating an appliance is provided. The method includes initiating a flow of a liquid into a sump of the appliance, noting a first time, t1, that corresponds to about the step of initiating, detecting the liquid with a turbidity sensor, logging a second time, t2, that corresponds to about the step of detecting, and determining a time interval based at least in part upon t1 and t2.
In a third embodiment, a method for operating an appliance is provided. The method includes initiating a flow of a liquid out of a sump of the appliance, noting a first time, t1, that corresponds to about the step of initiating, detecting air with a turbidity sensor, logging a second time, t2, that corresponds to about the step of detecting, and determining a time interval based at least in part upon t1 and t2.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:
The present subject matter provides an appliance with features for determining a time interval for liquid flowing into and/or out of the appliance. For example, a flow of liquid into and/or out of a wash chamber of the appliance is initiated, and a first time is noted. A turbidity sensor is monitored until the sensor detects liquid or air respectively, and a second time is logged. A time interval is calculated based at least in part on the first time and the second time. Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
An inlet 160 is positioned adjacent sump 200 of appliance 100. Inlet 160 is configured for directing liquid into sump 200. Inlet 160 may receive liquid from, e.g., a water supply (not shown) or any other suitable source. In alternative embodiments, inlet 160 may be positioned at any suitable location within appliance 100 such that inlet 160 directs liquid into tub 104. Inlet 160 may include a valve (not shown) such that liquid may be selectively directed into tub 104. Thus, for example, during the cycles described below, inlet 160 may selectively direct water and/or washing fluid into sump 200 as required by the current cycle of the appliance 100.
Rack assemblies 130 and 132 are slidably mounted within the wash chamber 106. Each of the rack assemblies 130, 132 is fabricated into lattice structures including a plurality of elongated members 134. Each rack 130, 132 is adapted for movement between an extended loading position (not shown) in which the rack is substantially positioned outside the wash chamber 106, and a retracted position (shown in
The dishwasher 100 further includes a lower spray-arm assembly 144 that is rotatably mounted within a lower region 146 of the wash chamber 106 and above a tub sump portion 142 so as to rotate in relatively close proximity to rack assembly 132. A mid-level spray-arm assembly 148 is located in an upper region of the wash chamber 106 and may be located in close proximity to upper rack 130. Additionally, an upper spray assembly 150 may be located above the upper rack 130.
The lower and mid-level spray-arm assemblies 144, 148 and the upper spray assembly 150 are fed by a fluid circulation assembly 152 for circulating water and dishwasher fluid in the tub 104. The fluid circulation assembly 152 may include a drain pump 220 located in a machinery compartment 140 located below the bottom sump portion 142 of the tub 104, as generally recognized in the art. Each spray-arm assembly 144, 148 includes an arrangement of discharge ports or orifices for directing washing liquid onto dishes or other articles located in rack assemblies 130 and 132. The arrangement of the discharge ports in spray-arm assemblies 144, 148 provides a rotational force by virtue of washing fluid flowing through the discharge ports. The resultant rotation of the lower spray-arm assembly 144 provides coverage of dishes and other dishwasher contents with a washing spray.
The dishwasher 100 is further equipped with a controller 137 to regulate operation of the dishwasher 100. The controller may include a memory and microprocessor, such as a general or special purpose microprocessor operable to execute programming instructions or micro-control code associated with a cleaning cycle. The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH. In one embodiment, the processor executes programming instructions stored in memory. The memory may be a separate component from the processor or may be included onboard within the processor.
The controller 137 may be positioned in a variety of locations throughout dishwasher 100. In the illustrated embodiment, the controller 137 may be located within a control panel area 121 of door 120 as shown. In such an embodiment, input/output (“I/O”) signals may be routed between the control system and various operational components of dishwasher 100 along wiring harnesses that may be routed through the bottom 122 of door 120. Typically, the controller 137 includes a user interface panel 136 through which a user may select various operational features and modes and monitor progress of the dishwasher 100. In one embodiment, the user interface 136 may represent a general purpose I/O (“GPIO”) device or functional block. In one embodiment, the user interface 136 may include input components, such as one or more of a variety of electrical, mechanical or electro-mechanical input devices including rotary dials, push buttons, and touch pads. The user interface 136 may include a display component, such as a digital or analog display device designed to provide operational feedback to a user. The user interface 136 may be in communication with the controller 137 via one or more signal lines or shared communication busses.
It should be appreciated that the subject matter disclosed herein is not limited to any particular style, model, or other configuration of dishwasher, and that the embodiment depicted in
Sump 200 also includes a turbidity sensor 210. Turbidity sensor 210 is configured for measuring turbidity of a fluid in reservoir 230 of sump 200. For example, turbidity sensor 210 may output a signal (e.g., a voltage or current) to controller 137 corresponding to a turbidity of liquid measured by turbidity sensor 210. Turbidity sensor 210 can also be used to provide an output signal indicative of when sump 200 is empty. More specifically, turbidity sensor 210 can be used to determine when sensor 210 is measuring air as oppose to a liquid. Similarly, turbidity sensor 210 can be used to determine when sensor 210 is measuring both air and a liquid.
A drain level 204 is shown in
A fill level 202 is also shown in
As described above, the output of turbidity sensor 210 changes with corresponding changes in the turbidity of fluid being measured by turbidity sensor 210 and with changes between measuring a liquid versus measuring air or a liquid and air. Accordingly, turbidity sensor 210 has a different output depending upon whether it is measuring liquid, air, or a combination of liquid and air. For example, when turbidity sensor 210 is exposed to washing fluid (e.g., water and/or detergent), the output of turbidity sensor 210 is significantly different compared to the output of turbidity sensor 210 when exposed to air or liquid and air as can occur as the liquid level changes.
As may be seen in
Accordingly, a volume of liquid that fills the sump 200 to minimum detection height 216 corresponds to a turbidity sensor fill volume, Vtsf, of liquid—i.e. the amount of liquid that must be placed into appliance 100 and/or sump 200 before turbidity sensor 210 detects a change between measuring only air versus measuring both air and liquid. Vtsf may be measured in order to accurately determine the amount of liquid in sump 200 below minimum detection height 216. For example, during design or manufacture of sump 200, Vtsf may be measured or calculated. In alternative embodiments, Vtsf may correspond to any suitable volume that turbidity sensor 210 may reliably detect during filling of sump 200 with liquid, e.g., a volume of liquid that fills reservoir 230 to maximum detection height 214.
The maximum detection height 214 of turbidity sensor 210 corresponds to a height above which the turbidity sensor 210 cannot be used to detect changes in the level of liquid in the appliance 100. However, during draining of sump 200, turbidity sensor 210 may determine when liquid in sump 200 drops below maximum detection height 214. For example, during draining of reservoir 230 from fill level 202, output of turbidity sensor 210 will change when liquid (e.g., washing fluid) passes the maximum detection height 214 and the turbidity sensor 210 is exposed to air and liquid instead of just liquid.
Accordingly, a volume of liquid that fills sump 200 to maximum detection height 214 corresponds to a turbidity sensor drain volume, Vtsd—i.e. the volume of liquid that must remain in sump 200 for turbidity sensor 210 to measure only liquid rather than only air or air and liquid. Vtsd may be measured in order to accurately determine the amount of liquid in sump 200 at the maximum detection height 214. For example, during design or manufacture of sump 200, Vtsd may be measured or calculated. In alternative embodiments, Vtsd may correspond to any suitable volume that turbidity sensor 210 may reliably detect during draining of sump 200, e.g., a volume of liquid that fills reservoir 230 to minimum detection height 214.
Controller 137 may be programmed to complete or perform the steps of method 400. At 410, a flow of liquid into sump 200 of appliance 100 is initiated. For example, controller 137 may initiate the flow of liquid by adjusting inlet 160. However, initiating the flow of liquid into sump 200 may be accomplished via any suitable method.
At 420, a first time, t1, is recorded. For example, controller 137 may record t1 when inlet 160 is adjusted at 410 and liquid begins to flow into sump 200. Thus, t1 corresponds to about a time when liquid begins flowing into sump 200.
At 430, output from turbidity sensor 210 is monitored. Based on output of turbidity sensor 210, at 440, it is determined whether turbidity sensor 210 is still detecting only air or is also detecting a liquid. As discussed above, the output of turbidity sensor 210 changes with corresponding changes in the turbidity of fluid being measured by turbidity sensor 210 as well as changes from air to liquid or vice versa. Accordingly, turbidity sensor 210 will have a different output when exposed to liquid from inlet 160 compared to just air. Thus, controller 137 may detect a change in turbidity sensor 210 output as liquid passes the minimum detection line 216 and infer that turbidity sensor 210 is now sensing liquid and air.
At 450, a second time, t2, is recorded. For example, controller 137 may record t2 when turbidity sensor 210 detects liquid from inlet 160 in step 440. Thus, t2 may correspond to about a time when liquid from inlet 160 fills reservoir 230 of sump 200 to minimum detection height 216, which corresponds to fluid fill volume Vtsf.
At 460, time interval, Δt, is calculated as
Δt□=t2−t1. (1)
However, alternative formulas may also be used to calculate Δt. Δt is calculated at 460 to provide a measured value for the amount time needed for liquid entering sump 200 via inlet 160 to reach minimum detection level 216. With accurate Δt, appliance 100 may permit a specific amount of liquid to enter into sump 200 through inlet 160.
At 470, Δt is compared to a stored value. Thus, controller 137 may compare Δt to the stored value. At 480, if Δt is significantly different from stored value, controller 137 may replace the stored value with Δt. The stored value may be used, e.g., to estimate the amount of liquid entering sump 200. However, the stored value may be replace with Δt that has been calculated to more accurately reflect time needed for liquid to enter the sump 200 via inlet 160.
In additional embodiments, steps 410-450 may be repeated to generate a plurality of t1 and a plurality of t2. For example, steps 410-450 may be repeated two, three, four, five, or more times in order to generate a respective number of t1 and t2. At 460, the plurality of t1 and the plurality of t2 may be used to calculate Δt. By utilizing the plurality of t1 and the plurality of t2 at 460, Δt may be averaged and thus be more accurate.
In alternative embodiments, at 430, rather than detecting liquid from inlet 160 reaching minimum detection height 216, turbidity sensor 210 is calibrated such that liquid filling sump 200 to maximum detection height 214 results in a specific output (e.g., voltage or current) from turbidity sensor 210. Controller 137 may receive such specific output from turbidity sensor 210 and determine that liquid from inlet 160 has filled sump 200 to maximum detection height 214. For example, as detection range 212 is submerged in liquid from inlet 160 and the liquid approaches the maximum detection height 214, output from turbidity sensor 210 may approach the specific output, and controller 137 may infer that turbidity sensor 210 is detecting only liquid and, therefore, liquid has reached maximum detection height 214 and fills volume Vtsf.
In additional alternative embodiments, at 460, rather than Δt, a fluid fill rate, Ffill, is calculated as
where Vtsf is the turbidity sensor fill volume and Vc is the carryover volume. Alternative formulas may also be used to calculate Ffill. Ffill may be calculated at 460 to provide a measured value for rate at which liquid enters sump 200 via inlet 160. Thus, with accurate Ffill, appliance 100 may permit a specific amount of liquid into sump 200 through inlet 160.
As discussed above, VP may be calculated based upon a fluid flow rate. For example, with Ffill measured using the above method 400, Ffill may be used to calculate Vp. For example, controller 137 may adjust inlet 160 such that liquid is entering sump 200. As will be understood by those skilled in the art, with Ffill known, controller 137 may permit liquid to enter sump 200 for a specific amount of time such that a particular Vp fills reservoir 230.
Controller 137 may be programmed to complete or perform the steps of method 500. At 510, a flow of liquid out of sump 200 of appliance 100 is initiated. For example, controller 137 may activate drain pump 220 in order to begin draining reservoir 230 of liquid when liquid fills reservoir 230 to fill level 202. However, initiating the flow of liquid out of sump 200 may also be accomplished via any other suitable method.
At 520, an additional first time, t1a, is recorded. For example, controller 137 may record t1a when drain pump 220 is activated at 510 and liquid begins to flow out of sump 200. Thus, t1a corresponds to about a time when liquid begins flowing out of sump 200.
At 530, an output from turbidity sensor 210 is monitored. Based on output of turbidity sensor 210, at 540, it is determined whether turbidity sensor 210 is detecting liquid. For example, controller 137 may determine whether turbidity sensor 210 is still sensing only liquid disposed in sump 200 or whether drain pump 220 has removed sufficient liquid from reservoir 230 such that at least part of detection range 212 of turbidity sensor 210 is exposed to air.
As discussed above, the output of turbidity sensor 210 changes with corresponding changes in the turbidity of fluid being measured by turbidity sensor 210 as well as changes from air to liquid or vice versa. Accordingly, turbidity sensor 210 will have a different output when exposed to liquid compared to just air. Thus, controller 137 may detect a change in turbidity sensor 210 output as liquid drains passed the maximum detection height 214 and at least a portion of detection range 212 of turbidity sensor 210 is exposed to air to infer that turbidity sensor 210 is now sensing air and liquid rather than only liquid.
At 550, an additional second time, t2a, is recorded. For example, controller 137 may record t2a when turbidity sensor 210 detects air at 540. Thus, t2a may correspond to about a time when drain pump 220 has removed liquid from sump 200 such that the level of liquid in the sump 200 passes the maximum detection height 214, which corresponds to fluid drain volume Vtsd.
At 560, an additional time interval, Δta, is calculated as
Δt
a□
=t
2a
−t
1a. (3)
However, alternative formulas may also be used to calculate Δta. Δta is calculated at step 560 to provide a measured value for the amount of time necessary for liquid to exit sump 200 via drain pump 220. With accurate Δta, appliance 100 may drain a specific amount of liquid from sump 200.
At 570, Δta is compared to a stored value. Thus, controller 137 may compare Δta to the stored value. At 580, if Δta is significantly different from stored value, controller 137 may replace the stored value with Δta. The stored value may be used, e.g., to estimate the amount of liquid exiting sump 200. However, the stored value may be replaced with Δta that has been calculated to more accurately reflect time needed for liquid to exit sump 200 via drain pump 220.
In additional embodiments, steps 510-550 may be repeated to generate a plurality of t1a and a plurality of t2a. For example, steps 510-550 may be repeated two, three, four, five, or more times in order to generate a respective number of t1a and t2a. At 560, the plurality of t1a and the plurality of t2a may be used to calculate Δta. By utilizing the plurality of t1a and the plurality of t2a at 560, Δta may be averaged and thus be more accurate.
In alternative embodiments, at 530, rather than detecting liquid draining from sump 200 passing maximum detection height 214, turbidity sensor 210 is calibrated such that turbidity sensor 210 sensing only air throughout detection range 212 results in a specific output (e.g., voltage or current) from turbidity sensor 210. Controller 137 may receive such specific output from turbidity sensor 210 and determine that drain pump has drained sump 200 of liquid such that liquid has drained passed the minimum detection height 216. For example, as detection range 212 drains of liquid, output from turbidity sensor 210 may approach the specific output, and controller 137 may infer that turbidity sensor 210 is exposed to only air, and, therefore liquid has drained passed the minimum detection height 216.
In additional alternative embodiments, at 560, rather than Δta, a fluid drain rate, Fdrain, is calculated as
where Vtsd is the turbidity sensor drain volume and Vp is the prime volume. Alternative formulas may also be used to calculate Fdrain. Fdrain may be calculated at step 560 to provide a measured value for the rate at which drain pump 220 removes liquid from sump 200. With accurate Fdrain, appliance 100 may drain a specific amount of liquid from sump 200.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
