Abstract:
A food waste disposer system, including a food conveying section and a motor section. A grinding section is coupled between the food conveying section and the motor section. The motor section includes an electric motor having a rotor. The rotor has a rotor shaft entrained in at least one self-compensating bearing assembly. In an aspect, the self-compensating bearing assembly has a split spherical bearing and a compressive bearing pocket.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/387,523, filed on Sep. 29, 2010. The entire disclosure of the above application is incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to food waste disposers, and to motors and bearing assemblies used therefor. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     A typical food waste disposer of the type that is disposed underneath a sink and is mounted to a drain opening of the sink includes a food conveying section, a motor section and a central grinding section disposed between the food conveying section and the motor section. The food conveying section conveys the food waste to the central grinding section. The grinding section typically has a shredder plate that is rotated relative to a stationary grind ring by an electric motor of the motor section. The motor has a rotor having a rotatable shaft coupled to the shredder plate. The electric motor is typically an induction motor, but may be other types of motors, such as brushless motors, universal motors, switched reluctance motors, and the like. 
       FIG. 1  depicts a prior art food waste disposer  100 , which is described in U.S. Pat. No. 6,854,673. U.S. Pat. No. 6,854,673 is incorporated by reference herein in its entirety. The disposer  100  may be mounted in a well-known manner in the drain opening of a sink using conventional mounting members of the type disclosed in U.S. Pat. No. 3,025,007, which is incorporated herein by reference in its entirety. The disposer includes an upper food conveying section  102 , a central grinding section  104  and a motor section  106 , which may include a variable speed motor. It should be understood that motor section  106  could also include a fixed speed motor, such as an induction motor. The central grinding section  104  is disposed between the food conveying section  102  and the motor section  106 . 
     The food conveying section  102  conveys the food waste to the central grinding section  104 . The food conveying section  102  includes an inlet housing  108  and a conveying housing  110 . The inlet housing  108  forms an inlet at the upper end of the food waste disposer  100  for receiving food waste and water. The inlet housing  108  is attached to the conveying housing  110 . A rubber o-ring  112  may be used between the inlet housing  108  and conveying housing  110  to prevent external leaks. A sealant bead may also be used instead of the rubber o-ring  112 . The sealant bead is preferably composed of a tacky, malleable material that fills any voids between the inlet housing  108  and the conveying housing  110  and tempers any irregularities in the opposing surfaces of the housings. Some suitable malleable materials for the sealant bead include butyl sealant, silicone sealant, and epoxy. 
     The conveying housing  110  has an opening  114  to receive a dishwasher inlet  116 . The dishwasher inlet  116  is used to pass water from a dishwasher (not shown). The inlet housing  108  and conveying housing  110  may be made of metal or injection-molded plastic. Alternatively, inlet housing  108  and conveying housing  110  may be one unitary piece. 
     The central grinding section  104  includes a grinding mechanism having a shredder plate assembly  118  and a stationary shredder ring  120 . In one embodiment, the shredder plate assembly  118  may include an upper rotating plate  122  and a lower lug support plate  124 . The upper rotating plate  122  and lower lug support plate  124  are mounted to a rotor shaft  126  of a rotor  184  of motor  180  of motor section  106 . A portion of the conveying housing  110  encompasses the grinding mechanism. The grinding mechanism shown in  FIG. 1  is a fixed lug grinding system. Alternatively, a moveable lug assembly could be used such as that disclosed in U.S. Pat. No. 6,007,006 (Engel et al.), which is incorporated herein in its entirety by reference. The grinding mechanism could alternatively use both a fixed lug assembly and a moveable lug assembly. 
     The shredder ring  120 , which includes a plurality of spaced teeth  128 , is fixedly attached to an inner surface of the conveying housing  110  by an interference fit and is preferably composed of stainless steel but may be made of other metallic material such as galvanized steel. As shown in  FIG. 1 , ramps  129  formed on the inside wall of the housing  110  may also be used to retain the shredder ring  120  in the housing  110 . 
     In the operation of the food waste disposer  100 , the food waste delivered by the food conveying section  102  to the grinding section  104  is forced by lugs  142  on the shredder plate assembly  118  against teeth  128  of the shredder ring  120 . Shredder plate assembly  118  may also include tumbling spikes  144 . The sharp edges of the teeth  128  grind or comminute the food waste into particulate matter sufficiently small to pass from above the upper rotating plate  122  to below the plate via gaps between the teeth  128  outside the periphery of the plate  122 . Due to gravity and water flow, the particulate matter that passes through the gaps between the teeth  128  drops onto a plastic liner  160  and, along with water entering into the disposer  100  via the inlet to the inlet housing  108 , is discharged through a discharge outlet  162  into a tailpipe or drainpipe (not shown). To direct the mixture of particulate matter and water toward the discharge outlet  162 , the plastic liner  160  is sloped downward toward the periphery side next to the discharge outlet  162 . The discharge outlet  162  may be formed as part of a die-cast upper end bell  164 . Alternatively, the discharge outlet  162  may be separately formed from plastic as part of the outer housing of the disposer. The outer surface of the discharge outlet  164  allows a tailpipe or drainpipe to be connected to the discharge outlet  162 . 
     An upper end bell  164  separates the central grinding section  104  and the motor section  106 . The motor section  106  is housed inside a housing  174  and a lower end frame  176 . The housing  174  may be formed from sheet metal and the lower end frame  176  may be formed from stamped metal. The housing  174  and lower end frame  176  are attached to the upper end bell  164  by screws or bolts  178 . 
     The motor section  106  includes motor  180  having a stator  182  and a rotor  184 . Stator  182  includes windings  194 . The rotor imparts rotational movement to the rotor shaft  126  of rotor  184 . The motor  180  is enclosed within the housing  174  extending between the upper end bell  164  and lower end frame  176 . The motor  180  may be a variable speed motor as described in U.S. Pat. No. 6,854,673 and controlled by a controller  220 . Alternatively, a brushless permanent magnet motor or an induction motor could be used. 
     The upper end bell  164  may dissipate the heat generated by the motor  180 , prevents particulate matter and water from contacting the motor  180 , and directs the mixture of particulate matter and water to the discharge outlet  162 . 
     The plastic liner  160  is attached to the die-cast upper end bell  164  by screws or bolts  166 . The upper end bell  164  is attached to the conveying housing  110  by screws or bolts  168 . To prevent external leaks, a ring bracket  170  and o-ring or seal  172  may be used to secure the connection between the conveying housing  110  and the upper end bell  164 . 
     To align the rotor shaft  126  and, at the same time, permit rotation of the rotor shaft  126  relative to the upper end bell  164 , the upper end bell  164  has a central bearing pocket  165  that houses a bearing assembly  200 . In one embodiment, the bearing assembly  200  encompasses the rotor shaft  126  and comprises a sleeve bearing  202 , a sleeve  204 , a rubber seal  206 , a slinger  208  and a thrust washer  210 . The sleeve bearing  202  is pushed into the smaller portion of the central bearing pocket  165 . The sleeve bearing  202  is preferably made of powered metal having lubricating material. The thrust washer  210  is placed on top of the bearing  202 . The steel sleeve  204  encompasses the rotor shaft  126  and is positioned above the thrust washer  210  and sleeve bearing  202 . The steel sleeve  204  resides on an upper end portion  127  of the rotor shaft  126 . The upper end portion  127  is shaped as a double D to receive the shredder plate assembly  118 . A bolt  211  is used to hold the shredder plate assembly  118  to the rotor shaft  126 . To keep out debris, rubber seal  206  slides over the steel sleeve  204  and rests in a larger portion of the central bearing pocket  165  of the upper end bell  164 . Steel cap or slinger  208  is placed on top of the rubber seal  206 . 
     The bottom of the rotor shaft  126  is permitted to rotate relative to the lower end frame  176  by the use of lower bearing assembly  212 . The lower bearing assembly  212  includes a housing  214  and a spherical bearing  216 . The spherical bearing  216  is preferably made of powdered metal having lubricating material. 
     Mechanical and electrical (magnetic) imbalances are known problems in the fabrication of electric motors. In some instances, the motor rotors are machined in order to improve the mechanical balance. Some motor manufacturers use in-line electrical testing of the rotors to improve the magnetic balance. 
     It is desirable to minimize the air gap between the bearing and rotor shaft to reduce bearing noise. In one known technique of improving the clearance between the rotor shaft and bearing, the rotor shafts are ground to very tight tolerances and the bearings used also have very tight tolerances. A secondary burnishing operation may also be performed on the bearings to improve the consistency of the inside diameter after assembly. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     In accordance with an aspect of the present disclosure, a food waste disposer system has a food conveying section, a motor section, and a grinding section disposed between the food conveying section and the motor section. The motor section includes a motor having a rotor with a rotor shaft entrained in at least one self-compensating bearing assembly. 
     In an aspect, the self-compensating adjusting bearing assembly has a split spherical bearing and a compressive bearing pocket in which the split spherical bearing is received. The compressive bearing pocket has a pocket angle so that a wall of the compressive bearing pocket exerts a compressive force on the split spherical bearing compressing it diametrally against the rotor shaft. 
     In an aspect, the split spherical bearing has an axial slit allowing the inside diameter of the split spherical bearing to conform to the diameter of the rotor shaft when the split-spherical bearing is compressed. 
     In an aspect, the rotor shaft may be placed in tension by incorporating thrust surfaces at each end of the motor section that provide the necessary force to compress the bearings. 
     In an aspect, when the motor section of the food waste disposer is in a vertical position, the weight of the rotor and the solenoid forces of the motor provide a force on the split spherical bearing to force it down and against the wall of the compressive bearing pocket. 
     In an aspect, the pocket angle can be changed from one self-compensating bearing assembly to another to vary the diametral force exerted by the compressive bearing pocket on the split spherical bearing. 
     In an aspect, a secondary source of diametral compression of the split spherical bearing (or bearings) and/or axial force on the split spherical bearing (or bearings) is provided. In an aspect, a secondary source of diametral compression is a spring situated to apply diametral compressive force against an outer diameter of the split spherical bearing. In an aspect, a secondary source of axial force includes an adjustable collar situated around the rotor shaft in a threaded opening in an end wall of the motor section, an adjustable collar situated in a threaded opening in an end bell of the motor section, or adjustable collars situated in both threaded openings. The adjustable collar (or collars) is tightened or loosened to adjust the pressure on the split spherical bearing. 
     In an aspect, an electric motor has a stator and a rotor. The rotor has a rotor shaft entrained in at least one of the above self-compensating bearing assemblies. In an aspect, the motor has opposed ends with one such self-compensating bearing assembly at one of the opposed ends and another such self-compensating bearing assembly at the other of the opposed ends. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments, do not include all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  shows a cross sectional view of a prior art food waste disposer; 
         FIG. 2  shows a cross-sectional view of a lower portion of a food waste disposer having a self-compensating bearing assembly in accordance with an aspect of the present disclosure; 
         FIG. 3  shows a cross sectional view of a self-compensating bearing assembly of the food waste disposer of  FIG. 2  in accordance with an aspect of the present disclosure; and 
         FIG. 4  shows a motor section of a food waste disposer having a self-compensating bearing assembly and components that apply an axial force thereto in accordance in accordance with an aspect of the present disclosure. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. 
     In accordance with an aspect of the present disclosure, a self compensating bearing assembly described below is used for the upper bearing assembly, the lower bearing assembly, or both of the food waste disposer  100  of  FIG. 1 . 
       FIG. 2  shows a lower portion of a food waste disposer  221  having upper and lower self compensating bearing assemblies  222 ,  224  at opposed ends  254 ,  256  of motor section  106 . Elements in common between food waste disposer  221  and food waste disposer  100  are identified with the same reference numbers with the following discussion directed to the differences. 
     In an aspect, upper self-compensating bearing assembly  222  includes an upper compressive bearing pocket  226  in which a split spherical bearing  228  that encompasses the rotor shaft  126  is received. Sleeve  227  is disposed around rotor shaft  126  at an outer side of split spherical bearing  228  and provides a thrust surface  252  against spherical bearing  228 . Alternatively, a thrust washer can be disposed between sleeve  227  and spherical bearing  228  to provide thrust surface  252 . Sleeve  227  is surrounded by a spring-loaded rubber seal  229 . 
     Split spherical bearing  228  may be retained in the upper compressive bearing pocket  226  by a bearing retainer (not shown). Where the vertical force applied by the rotor  184  is sufficient to retain split spherical bearing  228  in upper compressive bearing pocket  226 , the bearing retainer can be dispensed with. In an aspect, lower self-compensating bearing assembly  224  includes a lower compressive bearing pocket  232  in which a split spherical bearing  234  is received. 
     The rotor shaft  126  may be placed in tension by incorporating thrust surfaces  250 ,  252 , at opposed ends  254 ,  256 , respectively, of motor section  106  that provide the necessary force to compress the bearings. In the aspect shown in  FIG. 2 , lower self-compensating bearing assembly  224  has a thrust washer  236  around rotor shaft  126  that abuts a bottom of split spherical bearing  234 . A retainer  238  (such as a retaining clip or retaining ring) and a spring washer  240  are placed over thrust washer  236  to urge split-spherical bearing  234  up into lower compressive bearing pocket  232  and also urge rotor shaft  126  downwardly thus placing rotor shaft  126  in tension. This also urges split spherical bearing  228  into upper compressive bearing pocket  226 . In this embodiment, thrust washer  236 , c-clip  238  and spring washer  240  cooperate to provide thrust surface  250 . 
       FIG. 3  shows in more detail this embodiment of upper self-compensating bearing assembly  222  having split spherical bearing  228  and upper compressive bearing pocket  226 , which can also be utilized for lower self-compensating bearing assembly  224 . Split spherical bearing  228  has an axial slit  242  allowing an inside diameter  258  of split spherical bearing  228  to conform to an outside diameter  260  of rotor shaft  126  when split-spherical bearing  228  is compressed. Wall  244  of compressive bearing pocket  226  is shaped to have a pocket angle  246  so that wall  244  applies a diametral compressive force on split spherical bearing  228 , shown by arrows  248 , to minimize the clearance between the outside diameter of rotor shaft  126  and the inside diameter  258  of split spherical-bearing  228 . The split spherical bearing  228  may preferably be made of a composition including powdered metal and lubricating material. 
     It should be understood that the pocket angle  246  can be changed from one self-compensating bearing assembly to another to vary the diametral force exerted by the compressive bearing pocket  226  on split spherical bearing  228  from one self-compensating bearing assembly to another. 
     When motor section  106  of food waste disposer  221  is in a vertical position, such as when food waste disposer  221  is mounted to a sink, the weight of rotor  184  and the solenoid forces of the motor  180  provide a force on split spherical bearing  228  to force it down and against wall  244  of upper compressive bearing pocket  226  sufficient to compress split spherical bearing  228  due to the opposing diametral compressive force exerted by the upper compressive bearing pocket  226  on split spherical bearing  228 . The pocket angle  246  can be adjusted when designing the upper compressive bearing pocket  226  to achieve the proper balance between the weight of the rotor  184 , the spring rate of the split spherical bearing  228 , and the amount of diametral compression that the split spherical bearing  228  exhibits. 
     In an aspect, motor section  106  can be disposed in a horizontal position, as shown in  FIG. 4 . In this position, a secondary source of diametral compression and/or axial force may be provided. For example, a spring may be used to apply diametral compressive force against an outer diameter of the split spherical bearing. An adjustable collar (or collars) may be used to apply axial force to one or both of the split spherical bearings. 
       FIG. 4  shows a motor section  402  of a food waste disposer  400  in which axial force is applied. With the following differences discussed below, food waste disposer  400  is the same as food waste disposer  221  of  FIG. 2  and like elements will be identified with the same reference numbers. The self-compensating bearing assemblies are oriented horizontally with respect to each other in  FIG. 4  and will be referred to as left self-compensating bearing assembly  404  and right self-compensating bearing assembly  406 . Left self-compensating bearing assembly  404  includes a compressive bearing pocket  408  in which a split spherical bearing  410  that encompasses the rotor shaft  126  is received. A bearing retainer  412  abuts an outer side of split spherical bearing  410 . A coil spring  414  is disposed between an outer side of bearing retainer  412  and an inner side of an adjustable collar  416 . Adjustable collar  416  is threadably received in a threaded opening  417  in end bell  418  around rotor shaft  126 . It should be understood that coil spring  414  may be eliminated for more precise control of the diameter of split-spherical bearing  410 . 
     Right self-compensating bearing assembly  406  includes a compressive bearing pocket  420  in which a split spherical bearing  422  that encompasses rotor shaft  126  is received. A thrust washer  424  abuts an outer side of split-spherical bearing  422 . A spring washer  426  is disposed between thrust washer  424  and an adjustable collar  428 . Adjustable collar  428  is threadably received in a threaded opening  430  in a right end wall  432  of motor section  402  around rotor shaft  126 . 
     One or both adjustable collars  416  and  428  can be tightened or loosened in respective threaded openings  417 ,  430  to adjust the pressure on split spherical bearings  410 ,  422 . 
     It should be understood that the self-compensating bearing assembly described above can be used in applications other than food waste disposers. In such cases, the motor may include the self-compensating bearing assemblies. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the invention, and all such modifications are intended to be included within the scope of the invention. 
     The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a”, “an” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
     When an element or layer is referred to as being “on”, “engaged to”, “connected to” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to”, “directly connected to” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. 
     Spatially relative terms, such as “inner,” “outer,” “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.