Abstract:
The present invention provides cycle control that may be used among many different appliances. The cycle control provides a standard knob on the shaft that may be rotated and pulled out or pushed into activate the washing machine. The shaft is attached to a high-resolution encoder and a motor allowing software control of the actual movement and cycle definitions provided by the control.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. provisional application Ser. No. 60/988,927, filed Nov. 19, 2007, the entire contents of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates generally to cycle controls for controlling appliances and, more specifically, to a universal cycle control providing identical hardware that can be used on a wide range of appliances. 
         [0003]    Mechanical cycle controls are commonly used in household appliances. These cycle controls typically control operation of the appliance through a complex cam assembly and a series of cam followers. The cam assembly is typically rotated by a drive system such as an electric motor. The cam followers engage the cam surfaces as the cam assembly is rotated causing switch assemblies to trigger as each cam passes under a cam follower. The signals from these switch assemblies are, in turn, used to control an array of devices, such as relays, motors, and pumps that enable the function of the appliance. 
         [0004]    As the number of features and cycles available on household appliances increase, the complexity of these mechanical cycle controls similarly increases. Each cycle typically involves multiple events. For example, a simple cycle on a washing machine may include the steps of (1) filling the tub for the wash cycle, (2) agitating the laundry, (3) draining the tub, (4) filling the tub for the rinse cycle, (5) agitating the laundry, (6) draining the tub, and (7) spin drying the laundry. The number of steps can be compounded by extra features, such as pre-wash, extra rinse, and multiple wash times for various soil levels. The number of steps is further multiplied by adding multiple cycles, such as regular wash, permanent press, gentle cycle, and the like. As a result, the number of cams, cam followers, and switches required to manage multiple cycles becomes increasingly complex. 
         [0005]    Despite the internal complexity of these mechanical cycle controls, the timers are widely used on household appliances. This broad use is due in large part to a relatively simple user interface: a dial operator. The dial operator is typically used to rotate a shaft attached the cam assembly. By rotating the dial operator, the user is able to select the desired operating cycle. In addition, the dial operator and the associated markings around the operator provide visual feedback to the user as the appliance progresses through the steps of an operating cycle. Further, the dial operator can typically be pulled out and pushed in as a means for starting and stopping the appliance. Consumers have widely accepted these complex mechanical cycle controls primarily as a result of the relatively simple dial operator interface. Therefore, it is advantageous to maintain this familiar interface. 
         [0006]    However, a drawback of the conventional mechanical cycle control is that each timer must be customized for the particular appliance on which it is to be installed. The series of cams, cam followers, and switches must correspond to the particular cycles and features of that appliance. Therefore, there is a need for an improved cycle control that does not rely on the complex system of cams and switches to control the appliance while maintaining the familiar appearance and operation of the dial operator. Preferably, this improved cycle control could be used on multiple appliances with varying cycles and features without changing the physical construction of the cycle control. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention provides a cycle control that may be used among many different appliances. The cycle control generates a rotational position signal that has a higher angular resolution than required for a given appliance so that it may be used in a variety of different appliance applications with different cycles. Lookup tables, with different data, in a controller, interpret the angular position into arbitrary cycles to control the motor and valves of the machine. Such a universal cycle control may be mass-produced to decrease costs and to simplify repairs. Further, the cycle control may be configured to interface with a dial operator, providing a familiar user interface to facilitate consumer acceptance of the new device. 
         [0008]    In one embodiment of the invention, the appliance control includes a rotatable shaft having at least one set of rotational orientations corresponding to transitions between different steps within each cycle of the appliance and a rotary encoder communicating with the shaft to rotate therewith and providing a rotational position signal to indicate the absolute rotational orientation of the shaft at a higher angular resolution than required to detect the transitions between the different steps. An electric actuator coupled to the shaft provides rotation of the shaft among one of the sets of rotational orientations upon receipt of an electrical signal. 
         [0009]    Thus, it is one feature of this invention to provide a rotary encoder with sufficient resolution to be used with a variety of different appliances having different cycles and cycle steps. 
         [0010]    The shaft may be configured to move along an axis between a first position and a second position to activate an electric switch. 
         [0011]    It is thus another feature of at least one embodiment of the invention to provide operation that mimics a conventional washing machine control. 
         [0012]    The appliance control may include a controller receiving the rotational position signal and providing the electrical signal and executing a stored program to: (1) read the rotational position signal to determine a current step in the cycle of operation of the appliance according to a stored appliance look-up table; (2) operate an internal timer to time a predetermined interval; (3) at the conclusion of the predetermined interval output the electrical signal to move the shaft of the control a predetermined amount; and (4) repeat steps (1)-(3). 
         [0013]    It is thus another feature of at least one embodiment of the invention to move the timing function of the appliance control to software providing greater flexibility. It is another feature of at least one embodiment of the invention to use a readily programmable lookup table to map controlled angular position to cycles allowing the control to be used with a variety of different washing machines. 
         [0014]    The rotary encoder may include a circuit board adjacent to a shaft and a conductive wiper connected to the shaft to rotate therewith. A plurality of conductive pads may be circularly disposed around the circuit board wherein the plurality of conductive pads is individually electrically connected to the wiper to generate the rotational position signal. 
         [0015]    It is thus a feature of at least one embodiment of the invention to provide a low-cost rotary encoder of arbitrary resolution. 
         [0016]    A first resistor ladder having junctions between resistors that communicate with the conductive pads may produce a rotational position signal as a first voltage dependant on rotational position. 
         [0017]    It is thus a feature of at least one embodiment of the invention to transmit a rotary position signal to a remote controller without the need for multiple wires each carrying a binary signal per standard convention. 
         [0018]    A second resistor ladder having junctions between resistors may communicate with conductive pads different from the conductive pads communicating with the first resistor ladder to produce a second voltage dependant on rotational position, wherein the first and second voltage provide the rotational position signal in combination. 
         [0019]    It is thus a feature of at least one embodiment of the invention to provide a greater angular resolution than may be readily obtained using a continuous resistor ladder. 
         [0020]    The electric actuator may be a stepper motor and the electric signal is a set of phased electrical pulses. 
         [0021]    It is thus a feature of at least one embodiment of the invention to provide for a motor that naturally provides detents in rotation. 
         [0022]    These and other features, advantages, and features of the invention will become apparent to those skilled in the art from the detailed description and the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    Preferred exemplary embodiments of the invention are illustrated in the accompanying drawings in which like reference numerals represent like parts throughout, and in which: 
           [0024]      FIG. 1  is an exemplary application of the cycle control of the present invention illustrated in a simplified representation of a washing machine; 
           [0025]      FIG. 2  is a block diagram illustrating a control system incorporating the cycle control of the present invention; 
           [0026]      FIG. 3  is a front isometric view of one embodiment of the cycle control; 
           [0027]      FIG. 4  is a rear isometric view of the cycle control of  FIG. 2 ; and 
           [0028]      FIG. 5  is an exploded perspective view of the cycle control of  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0029]    The present invention provides a universal cycle timing system that may be used among many different appliances. In a preferred embodiment of the invention, as illustrated in  FIG. 1 , the cycle control  16  is used in a washing machine  10 . It is contemplated that the cycle control  16  may be used in other household appliances that use similar timing systems, including but not limited to a clothes dryer and a dishwasher. 
         [0030]    Referring to  FIG. 1 , an exemplary application of the cycle timing system illustrates a washing machine  10  providing a housing  12  having a console portion  14  displaying various controls and indicators including a cycle control  16  and indicator lights  18 . The cycle control  16  preferably engages a dial operator  20  having a handle portion  22  graspable by a user and an indicator portion  24  indicating the relative rotational position of the operator  20 . The indicator portion  24  provides visual identification to the user of the present operating mode of the washing machine  10  according to the cycle markings  26  on the washing machine  10 . 
         [0031]    Referring next to  FIG. 2 , a block diagram illustrates an exemplary control system  9  incorporating the cycle control of the present invention. A dial operator  20  interacts with the encoder  11 , motor  13 , and the switch  15  in the control system  9 . The encoder  11 , motor  13 , and switch  15  are illustrated schematically to identify electrical signals between each of the devices and a controller  19  in the system  9 . The encoder  11  receives a reference voltage signal  25  and a common voltage reference  27  from the circuit board  17  on which the controller  19  is mounted. The encoder  11  returns at least one and preferably two analog voltages  29  which are dependent on the rotational position of the encoder  11 . The analog voltages  29  are converted by analog to digital converters  31  and provide input signals  33  to the controller  19  which identify the rotational position of the encoder  13 . The controller  19  further issues commands  35  to the motor  13 . Typically these commands  35  will be in the form of a desired position of the motor  13  which is interpreted by a motor controller  37  which, in turn, generates the required electrical pulses  39  to rotate the motor  13 . The controller  19  further receives a signal  41  from a switch  15  used to start and stop operation of the control system  9 . 
         [0032]    The controller  19  includes a program which executes on the controller  19 . The program either contains knowledge of or an external identifier  43  may be provided, such as DIP switches or a selection resistor, to provide an indication of the appliance  23  on which the control system  9  is to be installed. The controller  19  uses this identification of the appliance  23  to access a look-up table  45  from memory  47 . The look-up table  45  contains information regarding the specific appliance  23  to be controlled. The appliance information in the look-up table  45  may include, but is not limited to, data such as the cycles of operation, the steps within each cycle, the rotational position that corresponds to each step of a cycle, the amount of time each step takes to execute, and the actuators used by the appliance  23 . The controller  19  uses the rotational position signals  33  from the encoder  11  to identify the desired step of execution within a cycle based on information from the look-up table  45 . The controller  19  then sends electrical signals  49  to different actuators within the appliance  23  based on the desired step of a cycle. For example, if the control system  9  is installed on the washing machine  10  of  FIG. 1 , these electrical signals  49  may control devices such as valves for controlling flow of water into and out of a washtub or a motor for driving the washing machine agitator or for spinning the washtub. 
         [0033]    Referring now to  FIGS. 3-5 , the cycle control  16  preferably includes a rear housing  28  and a front housing  30  removably engaged with the rear housing  28 . The front housing  30  preferably includes an upper surface  32  with a side surface  34  extending generally perpendicular to the upper surface  32 . The upper surface  32  is generally round with a hole  36  extending through the center of the upper surface  32 . At least one clip  38 , and preferably multiple clips  38  are incrementally positioned along the side surface  34  and extend generally parallel from the side surface  34 . At least one tab  40 , and preferably a pair of tabs  40  positioned on opposite sides of the upper surface  32 , are connected to the upper surface  32  and have an aperture  42  therein to provide a means for mounting the cycle control  16  to the appliance. 
         [0034]    The rear housing  28  preferably includes a generally round portion  44 , which engages the front housing  30 , and a generally rectangular portion  46  extending behind the round portion  44 . The round portion  44  includes a side surface  48  and at least one tab  50  mounted on the side surface  48 . Each tab  50  corresponds and is positioned to engage a clip  38  from the front housing  30 . The round portion  44  further includes an annular seat  52 , extending around the periphery of the rear of the round portion  44 , and a first aperture  54 , defined by the periphery of the seat  52  and in communication with the interior of the rectangular portion  46 . A second aperture  56  is positioned below the seat  52  and is generally rectangular. The second aperture  56  is similarly in communication with the interior of the rectangular portion  46 . The side surface  48  of the round portion  44  is mounted on a top surface  58  of the rectangular portion  46 . The rectangular portion  46  also has a side surface  60  extending generally perpendicular from the top surface  58 . 
         [0035]    The cycle control  16  further includes an electric motor  62 , preferably a stepper motor. The electric motor  62  preferably includes a stator  64 , a rotor  66 , and a connector board  68 . The electric motor  62  is mounted to and at least partially contained by the rear housing  28 . The connector board  68  is attached to the bottom of the stator  64  and extends through the second aperture  56 . The motor  62  preferably includes an annular plate  70  affixed to the rear of the rotor  66  such that it rotates with the rotor  66 . The diameter of the plate  70  is preferably less than the diameter of the stator  64 . The rotor  66  includes an aperture  72  extending therethrough. Preferably, the aperture  72  further includes a slot  74  extending thorough the aperture  72  configured to receive a key portion  78  of a keyed shaft  76  and to engage the shaft  76  for rotation. 
         [0036]    The shaft  76  may be moved inward to a first position or outward to a second position along the axis  80  of the shaft  76 . The shaft  76  includes an interior, spring-biased pin  82  to selectively retain the shaft  76  in either the first or the second position. The rear end  84  of the shaft  76  further includes a plunger  86  affixed to, and protruding axially from, the end of the shaft  76 . The front end  88  of the shaft  76  extends through the hole  36  in the front housing  30  and is configured to receive a dial operator  20 . 
         [0037]    The cycle control  16  further includes a generally round circuit board  90  preferably retained behind the seat  52  in the round portion  44  of the rear housing  28  and oriented generally parallel to the motor  62 . A preferred embodiment of the circuit board  90  includes a first annular trace  92  and a second annular trace  94  concentrically disposed on the board  90 . The circuit board  90  further includes five connecting pins  106 . One of the connecting pins  106  provides a common voltage level to the first trace  92 , and a second connecting pin  106  provides a voltage reference level to the second trace  94 . 
         [0038]    The second trace  94  further includes a series of pads  96  incrementally positioned along the trace  94 . The number of pads  96  corresponds to the number of steps available in the stepper motor  62 . Preferably the stepper motor  62  has forty-eight steps, but the stepper motor  62  may have any number of steps such that the incremental change in the rotational position signal has sufficient resolution to identify each mode of operation of the appliance. The first and second traces,  92  and  94 , are aligned on the circuit board  90  such that a wiper  98  affixed to the rear of the plate  70  mounted on the rotor  66  can simultaneously engage both traces. Two of the connecting pins  106  provide the rotational position signal corresponding to the position of the wiper  98 . 
         [0039]    The circuit board  90  further includes a lever switch  100 . The lever switch  100  is aligned with the plunger  86  and is toggled on and off as the shaft  76  is moved in and out. The fifth connecting pin  106  provides the electrical signal generated by the lever switch  100 . 
         [0040]    A rectangular circuit board  102  is mounted within the rectangular portion  46  of the rear housing  28 . The rectangular circuit board  102  interfaces with the connector board  68  of the motor  62  and with the connecting pins  106  on the round circuit board  90 . The rectangular circuit board  102  further includes an external connector block  104  for interfacing with an external microcontroller or for providing control signals to actuators within the appliance. Preferably, a motor control chip, not shown, mounted on the rectangular circuit board  102  provides voltages to the stator  64  through the connector board  68  in response to command signals input from the external connector block  104 . Alternatively, stator voltages may be generated externally and passed directly from the external connector block  104  through to the connector board  68 . 
         [0041]    Similarly, a microcontroller or other programmable logic device, as is known in the art, is preferably mounted on the rectangular circuit board  102  to process the rotational position signal from the connecting pins  106  and format the signal to be output through the external connector block  104  for use by an external microcontroller. Alternatively, the rotational position signal may pass directly from the connecting pins  106  to the external connector block  104 . 
         [0042]    In operation, the cycle control  16  is mounted in an appliance, such as the washing machine  10  illustrated in the exemplary application in  FIG. 1 . Preferably, a dial operator  20  is mounted on the front end  88  of the shaft  76  to facilitate the user interface. Alternatively, a knob, colored line on the shaft, or any other means of indicating the rotational orientation of the shaft to the user may be used. The user may grasp the handle portion  22  of the dial operator  20  either to adjust the rotational orientation of the shaft  76  or to push and pull the shaft  76  between the first and second positions. Under typical operation, a user first rotates the shaft  76  to the start of the desired operating cycle and then either pushes in or pulls out the shaft  76  to begin operation of the appliance. 
         [0043]    As the appliance is running, the electric motor  62 , and preferably a stepper motor, rotates the shaft  76  in cooperation with the cycle of operation. The stepper motor  62  may be easily rotated using the operator  20  when no power is applied to the stepper motor  62 . Further, the stepper motor  62  may be easily overhauled by a user while power is applied to the motor  62  if the user wishes to change the cycle of operation. The permanent magnet rotor  66  of the stepper motor  62  provides magnetic detent positions as a result of the natural magnetic attraction between the rotor  66  and stator  64  for tactile feedback to the user. The stepper motor  62  may be substituted with a DC gear motor or the like, the latter providing a slip clutch or the like allowing free rotation of the shaft  76  when power is not applied. 
         [0044]    The rotation of the rotor  66  simultaneously causes the slot  74  in the aperture  72  and the plate  70  affixed to the rear of the rotor  66  to turn. The slot  74  engages the key portion  78  of the shaft  76  resulting in rotation of the shaft  76 , and the plate  70  causes the wiper  98  to move in an arcuate path. As a result, the rotational orientation of the shaft  76  corresponds to the position of the wiper  98 . 
         [0045]    Preferably, the wiper  98  engages the circuit board  90  to generate the rotational position signal. The wiper  98  is oriented to continuously engage the first trace  92  and selectively engage pads  96  on the second trace  94 . The first trace  92  is held at an electrical common voltage level. The second trace  94  has an electrical reference voltage applied at one end of the trace  94 . Preferably, the second trace  94  is resistive in nature such that a voltage divider network is created between each of the pads  96 . Alternatively, other methods may be used to establish the voltage divider such as surface mount resistors placed between each pad  96 . As the wiper  98  engages each pad  96  along the second trace  94 , an electrical circuit is established, consisting of: the reference voltage input at one end of the second trace, a variable resistance between the input pin and the pad  96  presently engaged by the wiper  98 , and the common voltage level present in the first trace. The resulting rotational position signal is an analog voltage which varies between the common voltage level and the reference voltage level according to the resistance value at each pad  96  along the second trace. Preferably, the second trace  94  is further divided into two segments, each segment representing one half of the rotational movement of the shaft  76 . Each segment includes a complete voltage divider network and a corresponding analog voltage output. Alternatively, the second trace could be a continuous trace or any number of segments such that suitable angular position resolution, as would be known to one skilled in the art, is provided. The preceding description describes one embodiment of a rotational position feedback device, but it is contemplated that any means known to one skilled in the art could be used to generate the rotational position. For example, a light emitting diode with photoreceptors could be used in place of the resistive network, or discrete input signals could be generated to represent the rotational position rather than analog voltages. Other variations and modifications of the encoder are similarly within the scope of the present invention. 
         [0046]    As still another aspect of at least one embodiment of the invention, the electric motor  62  is preferably controlled by an external microcontroller. Alternatively, the microcontroller could be included on the second circuit board. The microcontroller is programmed to control operation of the appliance. 
         [0047]    The microcontroller may include an internal program to operate the cycle control  16  in a closed loop fashion, for example, accepting a rotational command and moving the stepper motor  62  to provide a reading on the encoder matching the rotational command. The microcontroller may move the stepper motor  62  in either direction, for example, to provide the shortest rotational path to a desired rotational position by providing voltages to the stator  64  through the connector board  68 . The microcontroller may also monitor movement of the encoder initiated by the user through manual rotation of the operator  20  without activation of the motor  62  and adjust operation of the appliance accordingly. The rotational position signal is input to the microcontroller to indicate the desired cycle of operation, and the program in the microcontroller controls operation of the appliance according to the selected cycle. The signal from the switch  100  is similarly input to the microcontroller to indicate when the appliance is to start or stop. By providing different programs within the microcontroller, the same cycle control may be used on multiple appliances, each appliance having a different set of cycles. 
         [0048]    It should be understood that the invention is not limited in its application to the details of construction and arrangements of the components set forth herein. The invention is capable of other embodiments and of being practiced or carried out in various ways. Variations and modifications of the foregoing are within the scope of the present invention. It also being understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention.