Power control modules are configured to regulate the delivery of power supply to loads (e.g., electrical appliances, for example, cooktop appliances with heating elements, ovens, warming display cases, warming cartridges, etc.) As such, power control modules include a user control mechanism to enable the user to specify the power level, or some other equivalent value, such as temperature, the user desires to have delivered to the loads, and a mechanism by which the power provided by an external power source is regulated and delivered to the load.
The efficiency of a power control module is often a function of the module's power rating (e.g., how much power the module can handle) and the module's size. Typically, the physical dimensions of the power module are proportional to the module's power rating. In general, the more power the module has to handle, the larger the physical dimensions of the module need to be. This relationship is partly the result of the larger components (e.g., power level reduction components), and partly the result of the module's size requirement to efficiently dissipate heat generated from the operation of the power control module.
In general, the invention features (a) a user control to generate a heat level input signal responsive to a user of an electrical appliance, (b) logic to generate an output signal having a duty cycle corresponding to the input signal, (c) an electromechanical device connected to apply power from a source to a load in response to the output signal, and (d) a housing to receive the electromechanical device.
In one aspect, a power module to regulate delivery of power to one or more loads is disclosed. The module includes a logic circuit configured to generate one or more control signals indicative of the power level to be applied from an external power supply coupled to the power module to the one or more loads, an electromechanical device configured to electrically connect the external power supply to the one or more loads based on the one or more control signals from the logic circuit, a user-controlled circuit configured to provide a signal indicative of a power level to deliver to the one or more loads, the signal is based on input received from a user-controlled actuator configured to be placed in one of a plurality of positions corresponding to user-provided input, and a housing configured to receive the electromechanical device.
Embodiments may include one or more of the following.
The electromechanical device may include a relay. The relay mat include a metal strip configured to be displaced from a first open position to a second closed position in which the external power source is electrically connected to the one or more loads, and a solenoid configured to cause the metal strip to be displaced from the first position to the second position when the solenoid is activated.
The housing may be constructed from electrically insulating materials.
The user-controlled circuit may include a switch having a plurality of positions that are each associated with a different power setting to control the logic circuit. The switch may include an encoder configured to produce an input signal to control the logic circuit based on the position of the user-controlled actuator. The switch may include a multi-position switch connected to a series of resistors to provide discrete resistance steps relative to the angular position of the multi-position switch.
The power module may further include the user-controlled actuator which may include a shaft having one end coupled to the user-controlled circuit.
The power module may further include a DC power supply circuit configured to provide DC current to, for example, the logic circuit and/or the electromechanical device. The DC power supply circuit may be a non-transformer based power supply circuit. The non-transformer based DC power supply circuit may include, for example, a diode, a capacitor and/or a resistor.
At least one of the DC power supply and/or the logic circuit may be disposed on a circuit board, and the circuit board may be mounted onto the housing.
The power module may be configured to be connected to apply power to at least two loads. The power module may be configured to control the power applied by the power supply circuit to the at least two loads independently.
Each position of the user-controlled circuit may be associated with a corresponding duty cycle, each corresponding duty cycle causing the electromechanical device to apply power for a duration determined by the corresponding duty cycle.
The logic circuit may include logic configured to generate the one or more control signals indicative of a duty cycle based on user-provided input, the logic including an input to receive a profile selection signal, and a data memory for profiles, each profile defining an association between input signals and output signals, and in which the logic uses the profile selection signal to select one of the profiles, the input signals being the same for each profile. The electromechanical device connects the external power supply to the one or more loads based on the output signals generated by the logic.
The power module may further include a zero crossing detection circuit configured to receive AC power from the external power supply and generate a signal indicative of the zero crossing of the AC power.
In another aspect, an electric appliance is disclosed. The electric appliance includes one or more loads, and at least one power module electrically coupled to the one or more loads. Each of the at least one power module includes a logic circuit configured to generate one or more control signals indicative of the power level to be applied from an external power supply coupled to the power module to the one or more loads, an electromechanical device configured to electrically connect the external power supply to the one or more loads based on the one or more control signals from the logic circuit, a user-controlled circuit configured to provide a signal indicative of a power level to deliver to the one or more loads, the signal is based on input received from a user-controlled actuator configured to be placed in one of a plurality of positions corresponding to user-provided input, and a housing configured to receive the electromechanical device.
In some embodiments, the electrical appliance may include a cooking top range. In some embodiments, the electrical appliance may include, but is not limited to, a warming display case, an oven, a warming cartridge, etc. In some embodiments, the one or more loads may be a heating element.
Other features and advantages of the invention will be apparent from the description and from the claims.
Like reference symbols in the various drawings indicate like elements.
Disclosed herein is a power module to regulate delivery of power to one or more loads, such as a heating element of a cook top. The power module includes a logic circuit configured to generate one or more control signals indicative of the power level to be applied from an external power supply coupled to the power module to the one or more loads, and an electromechanical device configured to electrically connect the external power supply to the one or more loads based on the one or more control signals from the logic circuit. A user-controlled circuit is configured to provide to the logic circuit a signal indicative of a power level to deliver to the one or more loads. The signal provided by the user-controlled circuit is based on input received from a user through a rotatable user-input mechanism, such as a knob attached to a rotatable shaft.
The power module also includes a housing configured to receive the electromechanical device. Vent openings formed in one or more of the housing's walls enable heat, generated, for example, by the electromechanical device, to be dissipated. Thus, by securing the electromechanical device directly to the housing to thereby enable efficient heat dissipation, a higher power rating for the power module can be achieved.
As shown, the power module 100 includes a user-control circuit 110 attached a to a user-controlled actuator 102 that enables a user to specify the desired power level to be delivered to the load. The user-controlled circuit 110 uses the mechanical position of the user-controlled actuator 102 to generate switch position signals that are provided to a logic circuit, which in turn generates control signals to regulate the operation of the electromechanical device 150.
Once a switch 120 becomes closed, through operation of the user-controlled actuator, a terminal 132 of a power source 130, coupled to the power module 100, is electrically coupled to a terminal 182 of the load 180 that is likewise electrically coupled to the power module 100. Another terminal 134 of the power source 130 is electrically coupled, via the electromechanical device 150, to another terminal 184 of the load 180. When the electromechanical device 150 is actuated to a closed position, whereby an electrical path is completed between the power source 130 and the load 180, a closed circuit is thus formed between the power source 130 and the load 180.
The electromechanical device 150 is configured to regulate current transmission to the load connected to the power module 100 based on the user-determined input. In some embodiments the electromechanical device 150 is a solenoid-based relay device such as a KLTF1C15DC48 relay from Hasco Components International Corporation. Other relays, which include all types of electromagnetic switching devices, may be used instead. In some embodiments, a TRIAC device may be used as a solid state switching solution in place of the relay. Under such circumstances, a TRIAC component can also be used to reduce the voltage level received from the external AC power source. Other types of switching devices may be used.
Electrical actuation of the electromechanical device 150, and thus regulation of the power delivered to the load 180, is performed using a logic circuit 140. A signal 142 generated by the logic circuit 140 in response to the output of the user-control circuit 110, causes the electromechanical device to intermittently open or close, in a controlled manner, the electrical path from terminal 134 of the power source 130 to the terminal 184 of the load 180. Thus, by controlling the period during which the electromechanical device is activated (and thus the electrical path between the power source 130 and the load 180 is closed), the power delivered to the load 180 is controlled. For example, the logic circuit 140 can generate the control signal 142 that causes the electromechanical device 150 to become active for a pre-determined period of time. This period during which the electromechanical is activated is sometimes referred to as the duty-cycle of the electromechanical device 150. Further description of controlling the duty cycle of an electromechanical device is provided, for example, in U.S. Pat. No. 6,951,997, entitled “Control of a Cooktop Heating Element.”
In some embodiments the logic circuit 140 generates the control signal 142 using look-up tables that are stored in a memory module 144 of the logic circuit 140. The logic circuit 140 can include any computer and/or other types of processor-based devices suitable for multiple applications. For example, a suitable computing device to implement logic circuit 140 is an 8-bit microcontroller device, such as a PIC12C509A microcontroller from Microchip Technology Inc.
The computing device that may be used to implement the logic circuit 140 can include volatile and non-volatile memory elements, and peripheral devices to enable input/output functionality. Such peripheral devices include, for example, a CD-ROM drive and/or floppy drive, or a network connection, for downloading software containing computer instructions. Such software can include instructions to enable general operation of the processor-based device. Such software can also include implementation programs to generate the control signal 142 for controlling the actuation of the electromechanical device 150. The logic circuit 140 may also include a digital signal processor (DSP) to perform some or all of the processing functions described above.
The duty cycle control signal 142 specifies both the turn on and turn off moments in each duty cycle. The logic circuit 140 bases the duty cycle control on the output signal 122 from the user-control circuit, which indicates the rotational position of the user-controlled actuator 102 (and hence the desired level of heating).
With reference to
The precise turn-on and turn-off times of the duty cycle are selected so that they occur approximately when the AC power source is crossing through zero, to reduce stress on the electromechanical device 150. For that purpose, the power module 100 includes a zero crossing detection circuit 160 that determines the zero crossing times and indicates those times to the logic circuit 140 using zero-crossing signal 162. Thus, the logic circuit 140 will generate duty-cycle control signal 142 so that the signal 142 substantially coincides with the zero-crossing of the external AC power source 130.
Power module 100 further includes DC power module 170 that generates DC power (via power line 172) from the AC power source 130. The DC power module 170 powers the logic circuit 140 and the electromechanical device 150. The DC power from module 170 is thus used to provide the power to switch the electromechanical device 150, and thereby control the delivery of AC power to the load 180.
Optionally, in some embodiments the power module 100 may also include a feedback power level adjustment mechanism to adjust the power delivered to the load 180. Particularly, a sensor may be coupled to the load to monitor power consumption by the load. An electrical control circuit could receive data from the sensor indicative of the power level at which the load is operating and compare that data to the desired power level as indicated, for example, by the duty-cycle control signal. If there is a discrepancy between the actual monitored power level as indicated by the sensor's data and the desired power level, the power level adjustment mechanism (which may be implemented on the logic circuit 140) can make necessary adjustments to the signal 142. The adjusted signal 142 will then cause the electromechanical device 150 to operate so that the discrepancy between the actual power level of the load 180 and the desired power level as specified by the user is minimized, or eliminated. This type of control mechanism is referred to a closed-loop adjustment mechanism.
As further shown in
Particularly, and with reference to
As further shown in
In the embodiment shown in
As further shown in
The user-controlled actuator 102 is further configured to activate the power module 100 when the user-controlled actuator is rotated to a position corresponding to one of the power-on positions. With reference to
As further shown in
As shown in
Disposed over the hole 242 of the circuit board 240 is a rotator 260, which is in the form of an annular disk configured to receive the user-controlled actuator 102, and is further configured to be rotated to a number of positions in response to rotation of the user-controlled actuator 102. Thus, movement of the user-controlled actuator 102 to a particular rotational position will result in a corresponding change of the rotational position of the rotator 260. The particular position of the rotator 260 causes the corresponding switch position signal 122 to be generated.
More particularly, and with reference to
In some embodiments the encoder circuit can be implemented as either an absolute or a relative rotary encoder. In some embodiments, a digital encoder can be used in which, for example, a unique 4 bit binary output is generated for each of sixteen (16) distinct positions of the user-controlled actuator 102.
Turning back to
The housing cover 280 includes U-shaped tabs 282 that extend perpendicularly to the surface of the cover 280. When the cover 280 is fitted over the housing 200, the tabs 282 are received within mounting slots 204 formed on the outer surface of the housing 200 (see
As noted above, in some embodiments the user-controlled actuator 102 is implemented as a shaft-based actuator 210 that is configured to be rotated to a plurality of positions. With reference to
The shaft 210 includes a ring 314. A key 316, extending from the ring 314, is received within a slot 320 defined in the rotator 218 when the shaft 210 is pushed inwardly towards the housing 200. Once the key 316 is received within the slot 320, rotation of the shaft 210 will cause the rotator 218 to rotate. As further shown in
The shaft 210 passes through the hole 242 formed on the circuit board 240 (shown in
In embodiments in which the logic circuit 140 is implemented using the 8-bit PIC12C509A microcontroller 542 from Microchip Technology Inc., as shown in
When the switch 120 is closed, AC power flows from the power line L1 to the DC power supply circuit 170. In some embodiments, the DC power source is implemented as a non-transformer-based power supply (sometimes referred to as a non-isolated or off-line power supply), that does not have to use coiled transformer devices to achieve power reduction. By avoiding the use of coiled transformer devices, the size requirements of the power module can be reduced, thus making the power module more compact. The power source 170 can thus be implemented using a circuit that includes diodes to rectify the AC power provided by AC power source 130, and resistors and capacitors to effect the power-level reduction.
Accordingly, in some embodiments the external power supply is half-wave rectified by diode 572, filtered by electrolytic capacitors 574a and 574b, and regulated by zener diodes 576a and 576b and resistors 578a and 578b to produce a DC power supply, which is used to power the logic circuit 140 and the electromechanical device 150.
Also shown in
In some embodiments generation of the duty cycle control signal is synchronized to zero-crossing of the AC voltage provides by AC power source 130. Thus, the actual switching of the electromechanical is performed only after pin 2, which is coupled to the transmission line from the AC power source 130, transitions from low to high, and when the duty cycle control signal 142 is high. After the duty control signal 142 goes low, the switching is again performed only after pin 2 transitions from low to high. Arcing between the contacts 558 of the relay 552 is reduced when the relay 552 is switched at or near the zero crossing points of the AC voltage waveform. This has the effect of reducing contact erosion and prolonging the useful service life of the relay 552.
Although not shown in
In the analog encoder implementation, the logic circuit 140 may use a capacitive charging circuit to convert a resistance-based switch position signal 122 to time periods, which can be easily measured using the logic circuit (such as the microcontroller 542, also shown in
As further shown in
In some embodiments, the power module 100 may be manufactured for use with different appliances having different profiles (e.g., two different electric range models). The appliances may be from the same manufacturer or different manufacturers. For this purpose, the processor of the logic circuit 140 may be pre-loaded with two profiles, such as profile A 402 (
In some embodiments, the power module 100 may be manufactured with trace wiring connecting the profile selection pin 648 of the microcontroller 542 to supply voltage and supply ground, thus configuring the power module 100 to use only one specific profile from the various profiles that may be stored on the look-up table 144 of the logic circuit 140. Thus, during assembly of the power module 100, the appropriate trace wiring is punched out depending on which profile is to be used for that particular power module 100.
In other embodiments, the power module is manufactured with a profile selection switch that a homeowner can flip between one of two positions to select which of two, or more, pre-loaded profiles of the logic circuit 140 should be used in interpreting the switch position signals.
The remainder of circuit 600 is substantially the same as circuit 500 shown in
Once generated, the duty cycle control signals 742a and 742b are provided to electromechanical devices 750a and 750b, respectively, to control the switching operations of the electromechanical devices 750a and 750b. When one of the electromechanical devices 750a and 750b is switched to its closed position, power from an AC power source is provided to the respective load coupled to the electromechanical device.
In some embodiments, the logic circuit 740 is configured to generate the duty cycle control signals independently of one another. Thus, the various loads controlled through the logic circuit 740 can be controlled independently and set to different power levels without regard to the power level the other load is set to.
Other power module configurations (e.g., a power module in which a single logic circuit can control power delivery to three or more loads) may also be implemented.
A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.
This application is a continuation-in-part application of and claims priority to U.S. application Ser. No. 11/242,629, entitled “Control of A Cooktop Heating Element”, and filed on Oct. 3, 2005 now U.S. Pat. No. 7,304,274, which itself is a continuation application of U.S. application Ser. No. 10/206,885, now, U.S. Pat. No. 6,951,997, filed Jul. 26, 2002, the contents of which are hereby incorporated by reference in their entirety.
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Number | Date | Country | |
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Parent | 10206885 | Jul 2002 | US |
Child | 11242629 | US |
Number | Date | Country | |
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Parent | 11242629 | Oct 2005 | US |
Child | 11548396 | US |