Abstract:
An ice maker for a refrigerator/freezer having a control module for more reliably driving a rotatable ice ejector for removing ice bodies from a mold of the ice maker and for refilling mold cavities with water. The control module has an ice ejector drive with a drive coupling that includes a gear wheel and an ejector shaft section, both made of hard plastic material, preferably a polymide resin, for transmitting higher torque to the rotary ice ejector without failure of the plastic drive components. In one embodiment, a drive sleeve on the gear wheel and a drive shaft section have a spline coupling for more effectively distributing driving forces in the drive coupling. In another embodiment, a metallic collar is tightly positioned over the gear wheel sleeve for enhancing torque transmission in the drive coupling. The control module further is operable for refilling the ice maker mold cavities to a predetermined level during each cycle of operation notwithstanding slight alterations in positioning of water fill switching contact due to manufacturing tolerances or forces to which the ice maker is subjected during shipping, handling or installation.

Description:
FIELD OF THE INVENTION 
   The present invention relates generally to ice makers, and more particularly, to an improved drive and control module for ice makers used in refrigerators and the like. 
   BACKGROUND OF THE INVENTION 
   Ice makers are known for use in refrigerator/freezers, such as shown in U.S. Pat. No. 5,261,248, which include a mold in which water is frozen to form cube or other shaped ice bodies and a rotatable ice ejector having a plurality of radial ice ejector arms. A drive module is provided for rotating a shaft of the ejector, which includes a drive motor that drives the periphery of a gear wheel having an axial sleeve that receives and drives a vertical cam shaft, the rotation of which in turn rotates the ejector during an ejection cycle, as well as control rotation of an ice level sensing arm. 
   During the ejection cycle, ice bodies sometimes can become lodged between the ejector arms and the strippers so as to impede or interrupt rotation of the ejector. In an effort to overcome such obstructions, drive motors with increased torque have been employed for the ice ejector. Because the drive train between the drive motor and the ejector shaft include plastic parts, including the gear wheel and the vertical cam shaft, when rotation of the ice ejector shaft is interrupted by a jammed ice body, the larger powered drive motor can cause such high torque between the gear wheel and vertical cam shaft that fracture or breakage of the plastic drive components can result. 
   A further problem with such ice makers concerns the water fill cycle of the ice maker. To control operation of the water refill cycle, an electrical water fill contact of the control module will periodically contact a relatively moveable circumferential track of a face cam circuit mounted on the gear wheel. In order to selectively adjust the fill cycle time (and hence the water depth in the ice maker mold) the contact is radially positionable by means of an adjustment screw and the start up location is determined by an angled groove in the rotatable circuit track. 
   To establish the proper fill level, the adjustment screw for the water fill contact must be precisely set. This typically requires a multiplicity of assembly inspections and a water fill check procedure. Furthermore, after the contact position has been properly determined, shipping and handling of the ice maker, as well as subsequent installation in a refrigerator/freezer, can alter the radial position of the contact and hence cause unwanted changes in the water refill time. Moreover, since the contact adjustment screw can protrude from the device, it can impede packaging and be subject to breakage or damage during handling of the ice maker. Thus, while heretofore the adjustable positioning of the water refill contact relative to the gear contact track was intended to enable a precise fill level in the mold, it has resulted in uncertainty and water fill cycle problems in the field. 
   OBJECTS AND SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide an ice maker having a drive control module that is simpler in design and more reliable in operation. 
   Another object is to provide an ice maker as characterized above which has an ice body ejector drive that is less susceptible to fracture or failure in the event of an ice cube jam during an ejection cycle. 
   A further object is to provide an ice maker of the foregoing type having a control module that can be assembled with the ice maker to precisely control the water fill cycle without factory testing. 
   Still another object is to provide an ice maker of the above kind that has a control module in which the water fill cycle is substantially unaffected by alterations in the radial position of a water fill control relative to a rotatable face cam circuit track of the control. Yet a further object is to provide such an ice maker in which the control module has a water fill contact the position of which is less susceptible to alternation during shipping and handling of the ice maker, or during installation in a refrigerator/freezer. 
   Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which: 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a fragmentary perspective of a refrigerator ice maker in accordance with the invention; 
       FIG. 2  is an enlarged fragmentary vertical section of the illustrated ice maker taken in the plane of line  2 — 2  in  FIG. 1 , with certain parts removed for clarity; 
       FIG. 3  is an enlarged exploded perspective of one embodiment of an ice ejector drive coupling in accordance with the invention; 
       FIG. 3   a  is an enlarged fragmentary perspective of a drive sleeve of the gear wheel shown in  FIG. 3 ; 
       FIG. 4  is a sectioned perspective of the drive coupling shown in  FIG. 3  in assembled condition; 
       FIG. 5  is an exploded perspective of an alternative embodiment of ice ejector drive coupling in accordance with the invention; 
       FIG. 6  is an enlarged fragmentary perspective of a drive sleeve of the gear wheel shown in  FIG. 5 ; 
       FIG. 7  is a side elevational view of a face cam electrical circuit of the control of the illustrated ice maker; 
       FIG. 8  is an enlarged fragmentary vertical section and side elevational view of a side plate of the control module of the illustrated ice maker, also taken in the plane of line  2 — 2  in  FIG. 1 , with certain parts removed for illustrating the electrical control; 
       FIG. 9  is an enlarged side elevational view of the water fill contact shown in  FIG. 8 ; and 
       FIGS. 10–13  are enlarged fragmentary sections of the water fill contact and its mounting in the illustrated control, taken in the planes of line  10 — 10 ,  11 — 11 ,  12 — 12  and  13 — 13 , respectively in  FIG. 9 . 
   

   While the invention is susceptible of various modifications and alternative constructions, certain illustrated embodiments thereof has been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the invention to the specific forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions and equivalents falling within the spirit and scope of the invention. 
   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now more particularly to  FIG. 1  of the drawings, there is shown an illustrative ice maker  10  in accordance with the invention. It will be understood that the basic construction and operation of the ice maker is disclosed in the afore-referenced U.S. Pat. No. 5,261,248, the disclosure of which is incorporated herein by reference and need not be repeated in detail. 
   The illustrated ice maker, as depicted in  FIG. 1 , includes a mold  11  in which ice bodies are formed from water delivered to the mold  11  by a fill dispenser  12  fluidically connected to a solenoid valve  14  by a water supply line  15 . The solenoid valve  14  in turn is connectable to a suitable pressurized water supply. The ice maker  10  further includes a control module  18  disposed at the front of the mold  11  and arranged to operate an ice ejector  20 , which upon completion of a freezing cycle of water in the mold  11 , removes the ice bodies from the mold. The ice ejector  20  has a plurality of radial ejector arms  21  that rotatably engage and carry ice out of the mold  11 , which is stripped by strippers  22  and drop into an adjacent collecting bin  24 . A pivotably mounted ice level sensing arm  25  extends downwardly above the collecting bin  24  to sense the level of ice bodies in the bin  24 . The illustrated mold  20  includes a plurality of partition walls  28  extending transversely across the mold  20  to define a plurality of cavities in which a corresponding plurality of ice bodies are formed. The partition walls  28  may be formed with appropriate recesses  29  communicating between the cavities to permit the flow of water from cavity to cavity during a water fill cycle operation. It will be understood that removal of the ice bodies from the mold cavities may be facilitated by heating the underside of the mold  11  to free the ice bodies for ejection from the cavities by the ejector  20 . 
   The control module  18  includes a motor  30  having an output pinion  31  that drives the periphery of a relatively larger gear wheel  32  mounted on a front side of a side plate  34  of the control module  18 . The gear wheel  32  in turn drives a vertical cam shaft  35 , which in turn drives a central shaft  36  of the ice ejector  20 . The vertical cam shaft  35  in this case has a D-shaped opening  37  that receives the ice ejector shaft  36  for rotation therewith. The vertical cam shaft  35  carries a cam  38 , referred to in the art as a vertical cam, having a cam surface that cooperates with a lever mechanism  39  for controlling positioning of the ice level sensing arm  25  in a conventional manner in response to rotation of the cam  38 . The lever mechanism  39  in this case includes a lever arm  40  having a cam follower surface engageable with the cam  38  and being pivotal in response rotation of the cam shaft  35  for pivoting an actuator  41  to which the sensing arm  35  is fixed. 
   To reduce manufacturing costs, it is known to make various parts of the ice maker control module  18  of molded plastic, including the gear wheel  32 , vertical cam shaft  35 , level arm  40 , and actuator  41 . As indicated previously, in the event of an ice jam between the ejector arms  21  and the strippers  22  during an ice ejection cycle, large stresses can be imparted on the drive components by the drive motor  30  that can cause fracture or breakage of the plastic drive components, including particularly the gear wheel and/or cam shaft. 
   In accordance with one aspect of the invention, the drive gear and vertical cam shaft have a splined connection which more effectively distributes driving forces and substantially reduces the risk of fracture or part failure. In the illustrated embodiment, the gear wheel  32  has a central rearwardly extending sleeve  45  formed with an enlarged diameter cylindrical counter bore section  46  which defines an annular locating ledge  47 , and which communicates with a smaller diameter bore  48  that extends through a forward side of the gear wheel  32 . The vertical cam shaft  35  has a forward end that includes a cylindrical section  50  that is positionable within the cylindrical counter bore section  48  of the gear wheel-sleeve  45  and projecting locking legs  51  that extend forwardly through the central smaller diameter bore  48  of the gear wheel  32 . The locking legs in this case have tapered end surfaces  52  for camming the legs  51  together during forceful insertion through the gear wheel bore  48  and outwardly directed locking ledges  54  for lockingly engaging a forward side of the gear wheel  32 . 
   In keeping with the invention, the cylindrical counter-bore section  46  of the gear wheel sleeve  45  and the cylindrical section  50  of the vertical cam shaft  35  are formed with longitudinally extending, circumferentially spaced splines  55 ,  56 , respectively which are adapted for inter fitting, radial force transmitting engagement with each other. The splines  55 ,  56  in this case each have complimentary general V-shapes with peaks  58  and valleys  59  that may be rounded or squared. It will be understood that the splines  55 ,  56  of the gear wheel  32  and cam shaft  35  can be positioned longitudinally into assembled relation to each other for providing radial force transmission as an incident to operation of the drive motor  30  and rotation of the gear wheel  32 . Indeed, the spline connection has been found to permit transmission of substantially greater torque, up to 30% or more, through the drive train without failure of plastic drive components. While the theory of operation is entirely understood, it is believed that the increased surface area attributed to the engaging splines  55 ,  56  minimizes the magnitude of transmitted stresses between the gear wheel and vertical cam shaft that occur during high torquing, such as during temporary jamming of ice body between the mold and ejector arms during an ejection cycle. 
   It will be understood that while in the illustrated embodiment the gear wheel  32  drives the cam shaft  35 , which in turn is mechanically coupled to the ejector shaft  36  alternatively, the cam shaft  35  could be an integrated part of the ejector shaft  36 . For purposes herein, reference to a shaft section being operatively coupled to the ejector shaft is intended to mean a shaft section that is mechanically coupled to the ejector shaft or integral therewith. 
   An alternative embodiment of drive connection between the gear wheel  32  and vertical cam shaft  35  for improving torque transmission through the plastic drive components of the drive module  18  is shown in  FIGS. 5 and 6 , wherein items similar to those described above have been given similar reference numerals. In this embodiment, the vertical cam shaft  35  again has a pair of locking legs  51  that are positionable through a central bore of the gear wheel  32  into locking engagement with a forward side thereof. For transmitting torque between the gear wheel  32  and vertical cam shaft  35 , in this case the cylindrical drive sleeve  50  of the gear wheel  32  is formed with a pair of diametrically opposed rearwardly extending drive lugs  60  at its end that are positionable into inter fitting relation with opposed recesses in an axial end face of the cam shaft  35  adjacent opposite sides of the locking legs  51 . Upon assembly of the gear wheel  32  and cam shaft  35 , it can be seen that the drive lugs  60  will transmit rotational torque to the cam shaft  32  as an incident to operation of the drive motor  30 . 
   In carrying out this embodiment of the invention, an annular metal collar  61  is positionable in tight fitting relation about the cylindrical drive sleeve  50  of the gear wheel  32 . The metal collar  61 , which preferably is made of steel and press fit onto the gear wheel sleeve  50 , unexpectedly has been found to enhance torque transmission between the gear wheel  32  and vertical cam shaft  35  without fracture or cracking of the plastic drive components. The metal collar  61  is believed to reinforce the drive connection and thereby permit substantially greater torque transmission without part failure. 
   In accordance with a further aspect of the invention, the plastic drive components of the drive module  18 , and particularly the gear wheel  32  and vertical cam shaft  35 , are formed of a stress resistant material that further enhances torque transmission through the drive module to the ejector  20  without cracking or other failure of the plastic parts. To this end, in the illustrated embodiment, the plastic drive components are made from a polyamide resin. The resin can be any suitable polyamide resin, but preferably the resin is a nylon resin. Suitable nylon resins include, but are not limited to, nylon 6 (e.g., polycaprolactam), nylon 6/6 (e.g., poly(hexamethylene adipamide)), and nylon 6/12, (e.g., poly(hexamethylene dodecanediamide)), copolymers thereof, and mixtures thereof. Preferably, the polyamide resin is nylon 6/6 (e.g., poly(hexamethylene adipamide)), which typically is made via the polycondensation of hexamethylene diamine and adipic acid. In order to further increase the mechanical strength of the polyamide resin from which the drive components are made, the polyamide resin preferably further comprises a reinforcing filler, such as glass fibers. The polyamide resin can comprise any suitable amount of reinforcing filler. For example, when the reinforcing filler is a glass fiber, the polyamide resin preferably comprises about 20% to about 30% (e.g., about 25%) by weight glass fiber based on the total weight of the resin and reinforcing filler. Suitable commercially available resin/filler blends include, but are not limited to, the nylon 6/6 resins marketed by DuPont under the trademark Zytel®, such as Zytel® FR50HF NC010 nylon 6/6 resin, and the nylon 6/6 resins marketed by Solutia under the trademark VYDYNE®, such as VYDYNE® 909 nylon 6/6 resin. 
   For controlling operation of electrically responsive functions of the ice maker  10 , a face cam circuit  65  is mounted on a rear side of the gear wheel  32  of the control module  18 . As known in the art, the face cam circuit  65 , as depicted in  FIG. 7 , may define a plurality arcuate face cam circuit tracks of electrically conductive material. Rotation of the gear wheel  32  and face cam surface  65  in the counter-clockwise direction from a zero degree home position will sequentially move the arcuate tracks into electrical contact in relation with respective contacts mounted on the side plate  34  of the module  18  at radial positions corresponding to face cam circuit tracks for operating the electrically activated functions of the ice maker. 
   The water fill cycle of the illustrated ice maker  10  in which water is directed to the fill dispenser  12  for filling the compartments of the mold  11  is controlled by a track A of the face cam circuit  65 . As an incident to operation of the drive motor  30  and rotation of the gear wheel  32 , track A is movable into contact with a water fill contact  66 . The face cam circuit track A in this case is the most radially outwardly disposed face cam circuit track, as is the water fill contact  66 . Heretofore, as indicated above, it has been difficult to factory install such water fill contact for filling the mold cavities to a predetermined level without selective adjustable positioning of the water fill contact and factory testing of the water fill cycle. The setting of the water fill contact also can be altered during subsequent shipping, handling, or installation of the ice maker in a refrigerator/freezer resulting in unwanted changes in the water fill level. 
   In accordance with a further aspect of the invention, the face cam circuit track A and water fill contact  66  can be efficiently factory installed and assembled for establishing a predetermined water fill level in the mold and the water fill level will not be affected by slight alterations in the radial position of the water fill contact  66  during handling or shipping of the ice maker  10 . The water fill contact  66  in this instance has a generally elongated configuration comprising a first elongated section  68  having a contact head  69  extending transversely in a direction parallel to the circumferential line of movement of the face cam circuit track A past the contact  66 . The contact head  69  in this case has split fingers  70  that can be biased into engaging relation with the face cam circuit track A of an incident to circumferential movement of the face cam circuit A track passed the contact. Alternatively, it will be understood that the contact  66  can be in the form of a brush similarly oriented parallel to the line circumferential movement of the face cam circuit track. The illustrated water fill contact  66  in this case has a second elongated section  70  laterally offset from the first elongated section  68 , with a transverse leg  71  at the end thereof that is electrically connected to the control circuitry for the ice maker in a known manner. 
   The illustrated water fill contact  66  is mounted in channel-like recesses in the rear side of the module side plate  34  with the contact head  69  extending through an opening  72  in the side plate  34  into adjacent relation to the rear side of the gear wheel  32 . The first elongated section  68  of the water fill contact  66  is mountable in a channel recess defined by parallel walls  74 ,  75  and is formed with side wings  76  for biased engagement with the side walls  74 ,  75  for retaining the contact  66  in fixed relation between the walls. For retaining opposite longitudinal ends of the water fill contact  66 , and hence the radial position of the contact head  69  relative to the face cam circuit track A, the side plate  34  is formed with ribs  78 ,  79  between which opposite elongated ends of the water fill contact  66  abut. 
   During operation of the ice maker drive motor  30  and rotation of the gear wheel  32  and face cam circuit  65  from the zero position shown in  FIG. 7 , the water fill contact head  66  will initially be disposed in closely spaced relation to the rear face of the gear wheel  32 . Continued circumferential advancement of the face cam circuit track A will move and an inclined ramp  82  of an initial section  84  of the face cam circuit track A into engagement with the water fill contact  66  causing the fingers  70  of the contact head  69  to ride up the ramp  82  and be forced into biased engaging relation with the initial section  84  of the face cam circuit track A. Since in the illustrated embodiment, the initial section  84  of the face cam circuit track A is not electrically connected to the control circuitry for the ice maker  10 , it serves only to raise and bias the contact head finger  70  into sliding engagement with the track. 
   Continued circumferential movement of the cam face circuit track A will cause a gap  85  defined between a trailing edge  86  of the initial track section  84  of the face cam circuit track A and a leading edge  88  of a further operative section  89  of the face cam circuit track A to move under the water fill contact head  66 , with the edges  86 ,  88  defined by the gap  85  cleaning any foreign matter that may have accumulated on the contact fingers  70 . Engagement of the leading edge  88  of the operative section  89  of the face cam circuit track A with the water fill contact  66  will close an electrical circuit effective for energizing and opening the solenoid water supply valve  14 . The water supply valve  14  remains open during the period of circumferential movement of the operative section  89  of the face cam circuit track A passed the water fill contact  66  and is closed by de-enerization of the solenoid valve  14  when a trailing edge  90  of the operative section  89  of the face cam circuit track A circumferentially passes beyond the water fill contact  66 . 
   In keeping with the invention, the leading and trailing edges  88 ,  90  of the operative section  89  of the face cam circuit track A are designed such that a constant predetermined refill cycle is effected notwithstanding slight alteration in the radial position of the water fill contact head  69  relative to the face cam circuit track A through longitudinal movement of the water fill contact elongated sections  68 – 70 , such as can occur by reason manufacturing tolerances in the contact retaining ribs  78 ,  79  or forces to which the contact may be exposed during shipping/handling or installation of the ice maker. To this end, the leading and trailing edges of the operative section  89  of the face cam circuit track A are radially oriented with respect to the axis of rotation of the gear wheel and face cam circuit  65  such that regardless of slight changes in the radial position of the water fill contact head  69  the water fill time remains constant and unaffected. By reason of the radial orientation of the leading and trailing edges  88 ,  90  of the face cam circuit track A, which can be formed with close tolerances, the water fill contact  66  and face cam circuit  65  can be factory installed efficiently without tedious and time consuming assembly and test procedures. Moreover, since the water fill time, hence the water level in the mold, is governed entirely by the location of the leading and trailing radial edges  88 ,  90  of the face cam circuit track A the mold can be filled to the same predetermined water level during each fill cycle not withstanding slight alterations in radial positioning of the water fill contact during assembly or handling of the ice maker. 
   From the foregoing, it can be seen that an ice maker is provided that has a drive control module that is simpler in design and more reliable in operation. The module has an ice ejector drive that is less susceptible to fracture or failure in the event of an ice cube jam during the injection cycle, and the control module is operable for refilling the ice maker mold to the same predetermined level notwithstanding alterations in positioning of a water fill switching contacts due to manufacturing tolerances or forces to which the ice maker is subjected during shipping, handling or installation.