Patent Grant
8777138
This application claims the benefit of priority to U.S. Provisional Patent Application No. 61/145,545, filed Jan. 18, 2009, entitled “FEED CONTROL FOR SHREDDERS OF SHEET LIKE MATERIAL”, by Josh Davis et al. the disclosure of which is hereby incorporated by reference in its entirety.
The present disclosure is directed toward an indication assembly that selectively activates at least one LED when a programmed motor cool down condition is approaching and/or met, wherein the indication assembly is operatively associated with at least one sensor component in communication with the motor for detecting an increase in motor temperature related to an approaching overload condition.
Recent approaches to improve media shredders are directed toward a focus on preventive features, indication features, and a combination of the both. There is known a plurality of preventive detection features, which monitor a factor that may contribute to an approaching fault condition. One example of a commonly monitored factor is a thickness of media, wherein it is known that the thickness exceeding a predetermined threshold value may tend to jam the shredder device. There is also known a plurality of indication features, which warn users of the approaching fault condition. Examples of commonly displayed indicators include flashing or colored lights and messages. In this manner, it is anticipated that the user will respond to the warning with an action that may minimize the occurrence of the fault condition.
In one known shredder device, a progressive light indication system displays one of a number of different colored light emitting diodes (LEDs) during different stages of an approaching condition. More specifically, the factor that is monitored is a thickness of media, wherein the fault condition is a potential overload of the motor system. A predetermined thickness threshold is associated with a maximum media thickness of which the mechanical systems of the shredder device can tolerate without becoming inoperative. In this known device, a first light emitting diode (LED) illuminates when a detected media thickness is below a first threshold value. At least one second colored LED (having a color different from the first LED) illuminates when the detected media thickness exceeds the first threshold value but is below a second, greater threshold value. A third colored LED (having a color different from both the first and second colors) illuminates when the detected media thickness exceeds both the first and second threshold values. When the third indicator is illuminated, the mechanical systems may de-energize because the maximum thickness capability is reached.
Overly thick media may tend to draw an Amperage that causes a motor to stop working. Generally, the mechanical systems, such as, for example, a motor, gears, and rotating cylinders, are capable of handling media thicknesses within certain ranges. Stack thicknesses are tested as they relate to the number of Amps drawn on the motor. In most instances, the motor needs a period of relief before the shredder device can complete the project.
However, overly thick media is not the only cause of excessive loading on a motor. One aspect of the known progressive light indication system is that it monitors the approaching overload condition based only on media thicknesses. The preventive detection feature is mounted to and protrudes in an entrance of a feed slot. Therefore, the system fails to indicate any approaching excessive loading condition that may result from (the following) factors unrelated to media thickness: (1) chad backing up into the mechanical systems caused by a full bin capacity; (2) clogs that are caused by strips winding around a cutting cylinder or by strips trapped behind the cutting cylinder and frame; and, (3) bunched up or folded-over media caused by walking of the sheet when it is unevenly pulled in between the cutting cylinders.
A media shredder is therefore desired which includes a prevention detection feature and an indication feature, wherein the detection feature is capable of sensing an approaching motor overheat conditions irrespective of the causing factor. The present disclosure is directed toward a detection feature that aims to prevent an overload condition that may be caused by any one of multiple factors by monitoring and/or sensing motor temperature.
A first embodiment of the disclosure is directed toward an article destruction device that includes at least one moving component contacting an article and transforming the article. An electric motor drives the at least one moving component. A head assembly houses the at least one moving component and the electric motor. The article destruction device further includes an indication panel displayed on the head assembly having at least three visual indicators situated in sequence. Each one of the visual indicators is associated with a stage of an approaching condition. The condition that is monitored by the article destruction device is an approaching motor cool down period. Each separate stage toward motor cool-down period is associated with a temperature of the motor. A first of the at least three visual indicators lights when the temperature is below a first threshold. At least a second of the at least three visual indicators lights when the temperature exceeds the first threshold and is below at least a second threshold. A last in the at least three visual indicators lights when the temperature exceeds both the first and the at least second thresholds. Each of the first and second thresholds equivalent to a predetermined temperature.
A second embodiment of the disclosure is directed toward a media shredder including a progressive overheat assembly for indicating an approaching motor overload condition. The shredder includes a motor having a start winding and a main winding connected across a pair of switch terminals. The start winding is connected across the terminals by means of a thermostatic switch. A controller operatively associated with the motor stores at least one predetermined temperature threshold value. Current is moved through both the start winding and the main winding when the thermostatic switch is in a first closed operative state. The thermostatic switch moves from the first closed operative state to a second open operative state when the first temperature threshold is met. Current moves through only the main winding when the thermostatic switch is in the second operative state.
A third embodiment of the disclosure is directed toward a fault condition detection assembly for indicating an approaching motor overload condition in an article destruction device. The detection assembly includes a motor having a start winding and a main winding connected across a pair of switch terminals. A thermally responsive switching means connects the start winding across the terminals. The detection assembly further includes a visual indication system operatively associated with the thermally responsive switching means. The visual indication system includes a first visual indicator activated when the thermally responsive switching means is in a closed operation directing a current flow through both the main and the start windings. The visual indication system further includes at least a second visual indicator activated when the thermally responsive switching means is an open operation directing the current flow only through the main winding. The visual indication system additionally includes a last visual indicator activated when the thermally responsive switching means is in an open operation and directing no current flow through either the main or the start winding.
Applications of the present disclosure are intended for inclusion in article destruction devices, wherein at least one driven mechanical component operates on a foreign article. The present disclosure is more specifically intended for destruction appliances that receive a foreign article in a first form and manipulate the article to a second form. The article destruction devices disclosed herein include at least one mechanical system housed in a head assembly and at least one containment compartment situated adjacent thereto. The foreign article is received in a throat situated on the head assembly for guiding the article from an exterior of the device to the mechanical system(s). The mechanical system includes at least one piercing mechanism that may fragment the article into multiple units. The head assembly is positioned in proximity to the containment space such that the transformed article is moved from the mechanical system to the containment space. One article destruction device contemplated for use with the present disclosure is a fragmentation device, such as, for example, a shredder appliance 10.
A display 22 (synonymously referred to herein as “panel” and “indicator array”) is viewable from an outer face of the head assembly 14 and includes various indicators 30 that selectively activate when a fault condition is either approaching or is met. The present disclosure is directed toward an indication assembly that selectively activates when a programmed motor cool down condition is approaching and/or met, wherein the indication assembly is operatively associated with at least one sensor component in communication with the motor 16 for detecting increases in motor temperature related to an approaching overload.
The display 22 further includes at least one indicator 30 being indicative of a motor temperature as it relates to predetermined threshold temperatures. The present indication assembly includes a means for monitoring temperature of the motor 16. Situated on the display 22 (synonymously referred to herein as “panel”) and illustrated in
It is anticipated that any one of a number of factors can contribute to the approaching overheat caused by an increase in current drawn by the motor. One example includes a media thickness generally greater than a maximum thickness of which mechanical systems of the shredder can tolerate. Another example includes media, which can be within any thickness range, which tends to walk to one side of the shredder causing the motor 16 to compensate for folding and/or bunching up of media along one longitudinal extent portion of the cutting cylinder. Another example may be operating of the shredder 10 for extended lengths of time that are not customary. These examples are not limiting, however, as any number of contributing factors can cause a motor 16 to overload.
A first LED 30a (synonymously referred to as “bar” or “initial bar”) illuminates when the shredder 10 is initially turned on. Illumination of the first indicator 30a can be activated either by a change in operation as commanded by selection of on-off power switch 26 or similar manual selection or automatically by a sensor or similar functioning component detecting media inserted in the feed slot 20. As previously described, each next LED 30 in sequence can be arranged in an alternative manner with a height of the first LED 30a being at a lowest height and each next LED 30b-e (i.e., collectively referred to herein as “middle LEDs” or “LEDs along a middle array portion”) in sequence being at an increasing (
The array on the display 22 includes the first LED 30a, which is indicative of the shredder 10 becoming operational from an off-state. The display 22 includes a last LED 30f, which is indicative of the fault condition (i.e., cool down) being met. Therefore the last LED 30f is further indicative of a fault procedure being performed during a duration of at least when the last LED 30f is illuminated. The array further includes at least one middle LED 30b-e situated in between the first and the last LEDs 30a, 30f, wherein each one middle LED 30b-e is indicative of the approaching fault condition. There is no limitation made herein to a number of total LEDs 30 making up the array 22.
Each adjacent LED 30a-f is shown in the circuit diagram illustrated in
It is anticipated that no limitation is made herein to a color of each one LED 30a-f. In one embodiment, each one LED illuminates at the same color. In one embodiment, each LED illuminates at a different color, wherein each next LED in sequence on the array 22 increases in wavelength. For example, the first LED 30a in the array can illuminate at a wavelength approximating 510 nm. This first LED 30a can appear green, indicating that the shredder is operational. The last LED 30f in the array can illuminate at a wavelength approximating 650 nm. This last LED 30f can appear red, indicating that the shredder is not operational because the fault condition is determined. Each middle LED 30b-e in sequence from the first LED 30a to the last LED 30f can illuminate at increasing wavelengths in a range of from about 510 nm to about 650 nm. In this manner, each middle LED 30b-e can appear as generally yellow toward orange (cautionary) colors indicative that the continued operations are approaching the overload fault condition. In one embodiment, each middle LED 30b-f can include equal wavelengths of approximately 570 nm. There is no limitation made herein to a color or a wavelength range that any one or all LEDs 30 operate in so long as the illumination of the LED is indicative of a stage in the cool-down determination process.
In one embodiment, each one LED 30a-f can be continuous illumination. In one embodiment, each one LED 30a-f can blink. In one embodiment, each one LED 30a-f can be continuous illumination for a predetermined time and then blink for a predetermined time, and then return to continuous illumination. In this last embodiment, it is contemplated that the LED 30a-30e blinks immediately preceding an activation of the next LED in sequence, wherein the blinking is indicative of one stage advancing to a next stage approaching the default condition. In one embodiment, each preceding LED in the sequence continues to remain illuminated after a next LED in the sequence illuminates. In one embodiment, only one LED illuminates at any one time. In one embodiment, the first LED and only one middle LED illuminates at any one time. Each illumination is associated with a temperature of the motor approaching overload.
The predetermined temperatures are configured according to the diodes 32-42 illustrated in the circuit diagram of
As indicated in
Continuing with
The previously introduced TCO sensor 60 is incorporated on the motor 16 of the shredder 10 to protect the electric motor 16 from overworking. Conventional TCOs are based on a thermally responsive element that fuses in response to a thermal overload condition, thereby interrupting the flow of electrical power to the protected apparatus. One typical approach uses a spring-loaded contact pin or lead that is held in electrical connection with an opposing contact by means of a fusible material such as solder. Another typical approach utilizes one or more springs, which are independent from a pair of electrical contacts. The springs urge the electrical contacts apart when a stop material melts in response to an elevated temperature. Both of these approaches are undesirable because the TCO typically includes a complex arrangement of springs and contact elements that are mounted to a housing. Thus, these approaches are inherently costly, and they do not allow for a direct inspection of the TCO because both the fusible material and contact conditions are not usually visible through the housing.
The electrothermal motor starting assembly of this invention automatically deenergizes the start winding 66 of an electric motor 16 after a predetermined delay following the motor 16 first being energized. The shredder device includes, for this purpose, the thermally responsive switching means. One example of such thermally responsive switching means includes a snap-acting thermostatic switch 52. Another example of a thermally responsive switching means includes a thermistor controlled semiconductor current switching device.
In operation, when a supply voltage is initially connected to the motor 16, the sensor 52, such as a thermistor 52 (hereinafter synonymously referred to as “NTC sensor”) is in a cool, unheated state. A connection diagram for the thermistor 52 is illustrated in
Initially, the thermistor 52 is in an unheated state because the motor 16 is generally at a cooler temperature resulting from the period it was not energized (i.e., when the shredder 10 is not powered on or operational). The (optionally forward and reverse) power switch 26 (illustrated in the circuitry of
When supply voltage is delivered to the shredder 10 from the power cord 24, current is driven through both the start winding and the main winding XX. When the current flows through these start and main windings of the motor 16, the motor 16 heats from its first, cool (unheated) temperature to a second temperature. As the motor 16 heats, it simultaneously energizes the thermistor 52 connected thereto it. In this manner, the thermistor 52 self-heats.
Initially, the current flowing through the thermistor 52 is limited only by a relatively low resistance of the thermistor 52 in its cool state. Accordingly, the thermistor 52 heats relatively rapidly. After a predetermined delay for a bimetallic disc (of the thermistor 52) to reach its operating threshold temperature, the switch 52 opens and thus deenergizes the start winding. Once the elevated temperature causes the switch 52 to operate, the thermistor 52 continues to self-heat until it reaches an equilibrium temperature. The thermistor then stabilizes at its equilibrium temperature. More specifically, further self-heating of the thermistor 52 is limited by an increase of its resistance at the transition (i.e., predetermined threshold) temperature TR. Thus no separate switching mechanism is needed to reduce the energization of the heating cool down diode with a heating element. As long as the motor 16 is connected across the supply voltage, the thermistor 52 remains in its heated state at the equilibrium temperature/condition. When the motor 16 is subsequently deenergized by the thermostatic switch 64 moving from the closed to the opened state, the thermistor 52 rapidly cools and the thermostatic switch 52 returns to a closed position. The article destruction device 10 resets after the predetermined cool-down period. The reset operation allows for the motor 16 to be subsequently restarted.
As previously described, the thermally responsive switching means heats upon energization of the motor 16, by a PTC thermistor of the type whose electrical resistance increases relatively abruptly with increasing temperatures that are above a transition temperature. The thermistor 52 is connected to the motor windings such that it electrically energizes (i.e., self heats) when the motor is energized. The thermistor 52 heats this switching means until it reaches a first threshold temperature.
In one embodiment, the thermistor 52 can be operatively coupled to a plurality of switching means, wherein each one switching means is associated with a different temperature threshold value. The thermistor 52 actuates illumination of a respective one LED upon a change of each switching means 52 from a closed operative state to an open operative state. In one embodiment, the first threshold temperature may be in a range of from about 55° C. to about 70° C. In one embodiment, at least one threshold temperature can be in a range of from about 55° C. to about 75° C. In one embodiment, at least one threshold temperature can be from about 60° C. to about 80° C. In one embodiment, at least one threshold temperature can be in a range of from about 60° C. to about 85° C. In one embodiment, at least one threshold temperature can be in a range from 65° to about 85° C.
In one embodiment, the thermistor 52 heats this switching means 64 for a predetermined period, before it reaches the threshold temperature. When the thermistor 52 reaches a resistance that matches a resistance value associated with the threshold temperature, it deenergizes the start winding of the motor 16 by opening the switch manes 64. However, the thermistor 52 remains energized to maintain that the switching means 64 remains in its “open” operational state during the entire duration that the motor 16 remains energized. Furthermore, the current continues to flow through the main winding even after the start winding is de-energized. However, further self-heating of the thermistor 52 is limited by a relatively abrupt increase of its resistance above the transition, i.e., at least first threshold, temperature.
In other words, because the thermistor 52 is operatively coupled to a circuit across the start winding, it energizes concurrently with the start winding when the switch 64 is in the closed operational state. However, the start winding is de-energized after the switch 64 moves to the open operational state. Therefore, the thermistor 52 is maintained above threshold temperature by voltages induced in the start winding by operation of the motor 16.
Referring now to
The controller 56 includes a microprocessor and a memory, which stores an EC control method, at least one look-up table, and a counter variable. The look-up table includes at least one predetermined temperature. The microprocessor cooperates with conventional support circuitry such as power supplies, clock circuits, a cache memory, etc. and other components that may assist in executing software methods disclosed herein. It is contemplated that some of the process steps discussed herein as software processes may be implemented within hardware, s.a., e.g., circuitry that cooperates with the microprocessor to perform various steps. The controller 56 also includes input/output circuitry that forms an interface between the microprocessor and the user interface (display 22), D/A converter, ND converter, and/or charge counter.
The control apparatus is contemplated as being a general purpose computer that is programmed to perform control functions in accordance with the present disclosure. It is anticipated that the disclosure may be implemented as an application specific integrated circuit (ASIC) in hardware. As such, the process steps described herein are intended to be broadly interpreted as being equivalently performed by software, hardware, or a combination thereof. The software can be written in any suitable language, such as, for example, “C” programming language, to include the process steps illustrated in
Following the thermistor temperature meeting and/or exceeding the at least one threshold temperature, a second overheat temperature check is conducted at step s106 by a second sensor. More specifically, this second overheat temperature check s106 is conducted by a second sensor thermal cutoff sensor (TCO) situated on the motor. Preferably the first and second overheat temperature checks are repeated for more than two predetermined temperatures occurring for the circuit of
If the TCO determines that the motor temperature reaches the predetermined cool down temperature, the overheat LED light is activated at step s108. Furthermore, the motor is de-energized as the cool time period for the thermal cutoff switch is initiated at step s110. When the motor temperature cools to an unheated predetermined temperature, the process completes and the array of visual indicators resets.
However, if the preselected or predetermined cool-down temperature is not reached for the motor, a motor current overload check is done at step s112. If the current drawn on the motor exceeds a predetermined Amperage threshold, the motor reverses its drive (i.e., reverses rotation of the moving component) at step s114 for a predetermined time (s.a., e.g., a few seconds). However, if the current drawn on the motor is determined not to exceed a predetermined Amperage threshold, then a media presence sensor performs a check at step s116 to determine if there is an article inserted or present in the feed slot. If there is in fact media or an article detected in the feed slot, then the motor is driven forward at 118 to drive the moving component(s) (i.e., the counter-rotating cutting cylinders) for shredding sheet-like material. However, if the paper sensor check s120 determines that no article is present in the feed slot, then there is a delay of motor drive (i.e., cylinder movement) for a predetermined time (s.a . . . , e.g., three seconds) at step s120. After completion of the predetermined delay, operation of the motor is suspended or stopped at step s122.
In addition to the process disclosed above, additional or fewer checks can be carried out either before or following the indication process described herein.
The exemplary embodiment has been described with reference to the preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the exemplary embodiment be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
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