Abstract:
A drain pump of a washing machine is cyclically activated during a drain operation conducted as part of a spin cycle in a manner which reduces the run time of the pump. At least one dynamic operating parameter of the washing machine is sensed and used to control the operation of the drain pump. In accordance with a preferred embodiment of the invention, the rotational speed of the wash tub is sensed and, when a predetermined spin speed is maintained for a prescribed period of time, the drain operation is initiated. Water level, pump power and/or drive motor torque can also be utilized as pump cycling control parameters.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention pertains to the art of washing machines and, more particularly, to a pump cycling system for controlling a drainage operation in a washing machine. 
     2. Discussion of the Prior Art 
     During operation, a clothes washing machine proceeds through a series of wash and rinse cycles. At least a terminal portion of each rinse cycle includes a spin cycle portion wherein a clothes article containing tub or basket is spun at a relatively high speed in order to extract water from the clothes. During the spin cycle, a drain pump is typically run full time in order to remove water from the washer. For a substantial portion of the spin cycle, the rate at which water is removed from the clothes is much lower than the rate that the pump can function. This results in the pump working in a mixture of air and water. Such operating conditions can cause premature wear on the pump, as well as developing excessive noise. 
     To address these concerns, various systems have been proposed which function to limit the operating time of a washing machine drain pump. For instance, it has been proposed in the art to activate the drain pump for only a prescribed percentage of the spin cycle, during intermittent, predetermined periods throughout the cycle, for a timed duration which can vary with wash load, or simply based on a sensed water level within the machine. Although these systems aid in addressing the problems noted above, excessive pump operation times still exist in accordance with these prior art arrangements, particularly in connection with the timed pump operation based systems. Based on at least these reasons, there is a need in the art for a control system which will effectively and efficiently reduce the cycle time of a drain pump in a washing machine. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a system and method for effectively controlling the time a drain pump of a washing machine is activated during a drain operation conducted as part of a spin cycle. In accordance with the invention, at least one dynamic operating parameter of the washing machine is sensed and used to control the activation and deactivation of the drain pump in a cyclic manner. 
     In accordance with the most preferred form of the invention, activation of the drain pump is dependent upon extraction speed and time. More particularly, the spin speed of the washing machine tub is monitored and when this speed has dwelled at a specified speed for a predetermined amount of time, a controller is employed to automatically cycle the drain pump for a prescribed time period. In accordance with a second embodiment of the invention, the torque employed to drive the washing tub during a spin cycle is monitored to trigger a drain operation. That is, a sensed increase of torque to the washing tub is indicative of the presence of an excess of water. As the torque decreases, the pump is cycled off. These control arrangements can actually be employed individually or in combination in accordance with the invention. Furthermore, input from a water level sensor could be used in connection with an additional, redundant system, i.e., as a verification measure for use in combination with one or more of the dynamic based pump cycle time control systems of the invention. 
     Based on the above, it should be apparent that the system of the present invention relies upon one or more specific dynamic variables of the washing machine in order to accurately and effectively control the operation of the drain pump so as to minimize cycle times. In any event, additional objects, features and advantages of the present invention will become more readily apparent from the following detailed description of preferred embodiments when taken in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several views. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partially cut-away, perspective view of a horizontal axis washing machine incorporating a pump cycling control system according to the invention; 
     FIG. 2 is an exploded view of various internal components of the washing machine of FIG. 1; and 
     FIG. 3 is a cross-sectional view of the internal components of FIG. 2 in an assembled state. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     With initial reference to FIG. 1, an automatic horizontal axis washing machine incorporating the pump cycling control system of the present invention is generally indicated at  2 . In a manner known in the art, washing machine  2  is adapted to be front loaded with articles of clothing to be laundered through a tumble-type washing operation. As shown, automatic washing machine  2  incorporates an outer cabinet shell  5  provided with a front door  8  adapted to extend across an access opening  10 . Front door  8  can be selectively pivoted to provide access to an inner tub or spinner  12  that constitutes a washing basket within which the articles of clothing are laundered. 
     As is known in the art, inner tub  12  is formed with a plurality of holes  15  and multiple, radially inwardly projecting fins or blades  19  are fixedly secured to inner tub  12 . Inner tub  12  is mounted for rotation within an outer tub  25 , which is supported through a suspension mechanism (not shown) within cabinet shell  5 . Inner tub  12  is mounted within cabinet shell  5  for rotation about a generally horizontal axis. Actually, the rotational axis is angled slightly downwardly and rearwardly as generally represented in FIG. 3. A motor  27 , preferably constituted by a variable speed, reversible electric motor, is mounted within cabinet shell  5  and adapted to drive inner tub  12  through belt  28 . More specifically, inner tub  12  is rotated during both wash and rinse cycles such that articles of clothing placed therein actually tumble through either water, water/detergent or another washing fluid supplied within inner tub  12 . Given that inner tub  12  is provided with at least the plurality of holes  15 , the water or water/detergent can flow between the inner and outer tubs  12  and  25 . A pump  30  (see FIGS. 1 and 3) is provided to control the level of washing fluid within machine  2 , particularly the draining of the fluid from outer tub  25 . As will be detailed more fully below, the present invention is particularly directed to the manner in which pump  30  is operated so as to reduce cycling times. 
     The general manner in which the automatic washing machine  2  of FIG. 1 operates is well known in the art and is not considered an aspect of the present invention. Therefore, a full description of its operation will not be described here. However, for the sake of completeness, automatic washing machine  2  is also shown to include an upper cover  42  that provides access to an area for adding detergent, softeners and the like. In addition, an upper control panel  45 , including an LCD display screen  50 , is provided for manually establishing a desired washing operation. In the preferred embodiment shown, display  50  includes a plurality of selectable control areas or zones which can be accessed by a user to both program and operate washing machine  2 . In the most preferred form of the invention, display  50  takes the form of an LCD display, such as a 128× 96 dot matrix, touch screen display, which enables a user to readily review displayed data, preferably in alpha or word text format, and select from that data to establish and begin a desired washing operation. Display  50  could have the selectable areas at any location on the display. The manner in which washing machine  2  can be programmed is disclosed in U.S. Patent Application Ser. No. 09/741,067 entitled “Interactive Control System for a Laundry Appliance”, filed on Dec. 21, 2000, now U.S. Pat. No. 6,502,265, and incorporated herein by reference. 
     As best seen in FIGS. 2 and 3, in order to allow inner tub  12  to freely rotate within outer tub  25  during a given washing operation, inner tub  12  is spaced concentrically within outer tub  25 . This spacing establishes an annular gap  56  between the inner and outer tubs  12  and  25 . As will be discussed fully below, an axial gap is also created at the open frontal portions of inner and outer tubs  12  and  25 . During operation of washing machine  2 , the washing fluid can flow through gap  56  from inner tub  12  into outer tub  25 . In addition, small objects can also flow into the outer tub  25  through the axial gap. Unfortunately, it has been found in the past that some objects flowing through the axial gap can end up clogging or otherwise disrupting the normal operation of the pumping system, thereby leading to the need for machine repairs. In order to remedy this situation, it has been heretofore proposed to incorporate a flexible sealing device, generally indicated at 60 in FIGS. 1 and 3, which functions to bridge this gap between inner and outer tubs  12  and  25  to prevent such objects from flowing into the outer tub  25 . Further provided as part of washing machine  2 , in a manner known in the art, is a sealing boot  62  which extends generally between outer tub  25  and a frontal panel portion (not separately labeled) of cabinet shell  5 . 
     Reference now will be made to FIGS. 2 and 3 in describing the preferred mounting of inner tub  12  within outer tub  25  and the arrangement of both sealing device  60  and sealing boot  62  as the tumble cycle feature of the present invention is related to the presence of one or more of these structural elements. Inner tub  12  has an annular side wall  61  and an open front rim  71  about which is secured a balance ring  75 . In the preferred embodiment, balance ring  75  is injection molded from plastic, such as polypropylene, with the balance ring  75  being preferably mechanically attached to rim  71 . Inner tub  12  also includes a rear wall  77  to which is fixedly secured a spinner support  79 . More specifically, spinner support  79  includes a plurality of radially extending arms  81 - 83  which are fixedly secured to rear wall  77  by means of screws  84  or the like. Spinner support  79  has associated therewith a driveshaft  85 . Placed upon driveshaft  85  is an annular lip seal  88 . Next, a first bearing unit  91  is press-fit onto driveshaft  85 . Thereafter a bearing spacer  93  is inserted upon driveshaft  85 . 
     The mounting of inner tub  12  within outer tub  25  includes initially placing the assembly of inner tub  12 , balance ring  75 , spinner support  79 , lip seal  88 , first bearing unit  91  and bearing spacer  93  within outer tub  25  with driveshaft  85  projecting through a central sleeve  96  formed at the rear of outer tub  25 . More specifically, a metal journal member  99  is arranged within central sleeve  96 , with central sleeve  96  being preferably molded about journal member  99 . Therefore, driveshaft  85  projects through journal member  99  and actually includes first, second and third diametric portions  102 - 104 . In a similar manner, journal member  99  includes various diametric portions which define first, second and third shoulders  107 - 109 . Journal member  99  also includes an outer recess  111  into which the plastic material used to form outer tub  25  flows to aid in integrally connecting journal member  99  with outer tub  25 . 
     As best shown in FIG. 3, the positioning of driveshaft  85  in journal member  99  causes each of annular lip seal  88 , first bearing  91  and bearing spacer  93  to be received within journal member  99 . More specifically, annular lip seal  88  will be arranged between first diametric portion  102  of driveshaft  85  and journal member  99 . First bearing unit  91  will be axially captured between the juncture of first and second diametric portions  102  and  103 , as well as first shoulder  107 . Bearing spacer  93  becomes axially positioned between first bearing unit  91  and second shoulder  108  of journal member  99 . Thereafter, a second bearing unit  114  is placed about driveshaft  85  and inserted into journal member  99 , preferably in a press-fit manner, with second bearing unit  114  being seated upon third shoulder  109 . At this point, a hub  117  of a spinner pulley  118  is fixedly secured to a terminal end of driveshaft  85  and axially retains second bearing unit  114  in position. Spinner pulley  118  includes an outer peripheral surface  120  which is adapted to be connected to belt  28  driven in a controlled fashion by the reversible motor  27  in order to rotate inner tub  12  during operation of washing machine  2 . In order to provide lubrication to lip seal  88 , central sleeve  96  is formed with a bore  123  that is aligned with a passageway  124  formed in journal member  99 . 
     Outer tub  25  has associated therewith a tub cover  128 . More specifically, once inner tub  12  is properly mounted within outer tub  25 , tub cover  128  is fixedly secured about the open frontal zone of outer tub  25 . Although the materials for the components discussed above may vary without departing from the spirit of the invention, outer tub  25 , balance ring  75  and tub cover  128  are preferably molded from plastic, while inner tub  12  is preferably formed of stainless steel. Again, these materials can vary without departing from the spirit of the invention. For example, inner tub  12  could also be molded of plastic. 
     Outer tub  25  is best shown in FIG. 2 to include a plurality of balance weight mounting gusset platforms  132  and  133 , a rear mounting boss  136  and a front mounting support  137 . It should be realized that commensurate structure is provided on an opposing side portion of outer tub  25 . In any event, balance weight mounting platforms  132  and  133 , mounting boss  136 , mounting support  137  and further mounting boss  140  are utilized in mounting outer tub  25  within cabinet shell  5  in a suspended fashion. Again, the specific manner in which outer tub  25  is mounted within cabinet shell  5  is not considered part of the present invention, so it will not be described further herein. Outer tub  25  is also provided with a fluid inlet port  141  through which washing fluid, i.e., either water, water/detergent or the like, can be delivered into outer tub  25  and, subsequently, into inner tub  12  in the manner discussed above. 
     Furthermore, outer tub  25  is formed with a drain port  144  which is adapted to be connected to pump  30  for draining the washing fluid from within inner and outer tubs  12  and  25  during certain cycles of a washing operation. 
     As best illustrated in FIG. 3, inner tub  12  is entirely spaced from outer tub  25  for free rotation therein. This spaced relationship also exists at the front ends of inner and outer tubs  12  and  25  such that an annular gap  146  is defined between an open frontal zone  147  of outer tub  25  and an open frontal portion  149  associated with balance ring  75 . It is through a lower section of gap  146  that washing fluid can also flow from within inner tub  12  to outer tub  25 . 
     Flexible sealing device  60  is mounted so as to bridge gap  146  between inner and outer tubs  12  and  25  and, specifically, between balance ring  75  and tub cover  128 . Gap  146  is required because of deflections between inner tub  12  and outer tub  25  during operation of washing machine  2 . Sealing device  60  bridges gap  146  to prevent small items from passing through, but sealing device  60  is flexible so as to accommodate changes in the size of gap  146  resulting from deflections during operation. Sealing device  60  includes a first seal portion  151  that is fixed or otherwise secured to a rear or inner surface  152  of tub cover  128  and a second, flexible seal portion  155 , such as brush bristles or a plastic film, which projects axially across gap  146  and is placed in close proximity and most preferably in sliding contact with a front or outer surface  156  of balance ring  75 . As is also known in the art, sealing boot  62  includes an inner annular end  162  which is fixed sealed to tub cover  128 , an outer annular end  164  which is fixed to the front cabinet panel (not separately labeled) of cabinet shell  5  and a central, flexible portion  166 . As perhaps best shown in FIG. 3, flexible portion  166  actually defines a lower trough  168 . 
     In general, various wash cycles can be selected through display  50 , including “Normal”, “Extra Rinse” and “Stain Removal” cycles. During a normal washing operation, automatic washing machine  2  will proceed through a main wash cycle and a predetermined number of rinse cycles. In the main wash cycle, a preset amount of water is added to any detergent or other washing solution supplied in the areas beneath cover  42  and inner tub or spinner  12  is driven to tumble articles of clothing through the resulting solution. Periodically, it is preferable to alter the rotational direction of inner tub  12  during this period to vary the tumbling pattern. 
     After the wash cycle tumbling time period has elapsed, a drain cycle is initiated with a continued tumbling action. In the preferred embodiment, this tumble drain period lasts approximately 90 seconds. Following the tumble drain, inner tub  12  is subjected to a spin mode wherein inner tub  12  spins for approximately two minutes. At this point, the water/detergent solution has been substantially removed from within inner tub  12 , although the articles of clothing will certainly still possess a certain percentage of the solution. Next, the articles of clothing are subjected to the predetermined number of rinse cycles wherein inner tub  12  is filled to a predetermined level with water and placed in a rinse cycle tumble pattern. In the most preferred form, three rinse cycles are provided. In general, each of the rinse cycles sequentially incorporate a rinsing tumble mode, followed by a tumble drain, a pause drain and then a rinse cycle spin mode. Thereafter, a final draining occurs and inner tub  12  is allowed to coast to a stop position and the washing operation is completed. Further details of this overall operational sequence is described in commonly assigned U.S. Pat. No. 6,241,782 entitled “Horizontal Axis Washing Machine Incorporating Flush Tumble Cycle” issued Jun. 5, 2001, which is hereby incorporated by reference. 
     Washing machine  2  includes a central processing unit (CPU)  177  used to regulate tub drive controls  182  for motor  27 , cycle controls  184 , and pump  30 . As indicated above, the present invention is directed to the manner in which pump  30  is controlled in order to reduce cycling times. Therefore, until this point, the basic structure of washing machine  2  as described above is known in the art and has been described both for the sake of completeness and to provide support for the pump control system of the present invention which will now be described in detail. 
     As shown in FIG. 1, central processing unit (CPU)  177  incorporating a pump control circuit  179  used to regulate the operation of pump  30 . As also shown, CPU  177  is adapted to receive signals from a water level sensor  185 , an inner tub speed sensor  187  and a drive torque sensor  190  for motor  27 . During a spin or extraction phase of a washing operation, inner tub  12  is adapted to be rotated at increasingly high speeds. In accordance with the invention, when a predetermined speed is reached, pump  30  is activated. For instance, in the most preferred form, horizontal axis washing machine  2  is adapted to reach a final extraction speed of 800 rpm which is monitored by sensor  187 . Of course, the extraction speeds during other portions of the washing operation can vary and, accordingly, so will the threshold level for activation of pump  30 . In any event, when a signal of 800 rpm is received by CPU  177 , a timer  192  is initiated. If sensor  187  continues to indicate 800 rpm for one minute, pump control circuit  179  is used to cycle pump  30 . Therefore, the drain operation is performed when inner tub  12  reaches a constant, predetermined rotational velocity for a set period of time. In the most preferred form of the invention, pump control circuit  179  functions to cycle pump with a 15 second ON and 30 second OFF basis. This cycling operation continue until sensor  187  indicates a drop in the speed. Since this represents the final extraction or spin phase of the overall washing operation, at this point, the entire washing machine  2  would be turned off. However, it should be recognized that a corresponding cycling of pump  30  is performed in connection with each spin cycle, although the threshold speed will vary. 
     At this point, it should be readily understood that various changes and/or modifications can be made to the invention without departing from the spirit thereof. For instance, it is contemplated that pump  30  could be activated in the manner set forth above, while being deactivated based on other criteria. For instance, the power sent to pump  30  could be monitored. Based upon changes in the amount of power needed to operate pump  30 , pump  30  would be de-activated. That is, when the water level diminishes, the flow in pump  30  will be a combination of air and water. The power require to pump this combination would be significantly lower than just water. Therefore, a reduction in the operation of pump  30  under this condition would be warranted. 
     In a similar fashion, pump  30  could be partially or fully controlled in other ways or through a redundancy system to assure that the activation time of pump  30  is minimized. One particular approach takes a look at signals from water level sensor  185 . In this case, the cycling of pump  30  is regulated based on the water level in outer tub  25  of washing machine  2 . Specifically, when the water level is sensed to be close to a bottom portion of inner tub  12 , pump  30  is energized for a set amount of time. Therefore, pump  30  could also be cycled, even if the threshold speed requirement was not met, if the water level gets too high. In any case, it is preferable in accordance with the present invention to actually initiate the cycling of pump  30  when the water or washing solution comes close to or reaches the bottom of inner tub  12 . This can be estimated to be at the time the upper spin speed is reached as fully described above, directly through water level sensor  185  or, in accordance with a still further modification, by monitoring the torque used to drive motor  27  through tub drive controls  182 . That is, when the level of water reaches the bottom of the inner tub  12 , the torque needed to spin inner tub  12  increases significantly. Sensing this sharp rise in torque signifies a need to initiate a drain operation and, in accordance with the invention, pump  30  is cycled instead of running full time. In any event, the reduced pump cycle time system in accordance with the invention is only intended to be limited by the scope of the following claims.