Abstract:
A laundry machine has a tub and a spin basket in said tub. A drive assembly includes a shaft and agitator. The shaft passes through a wall of the spin basket. The agitator is located within the spin basket. A lost motion clutch is physically located in the tub. The lost motion clutch interconnects between the drive assembly and the spin basket and absorbs greater than one revolution of relative rotation.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to laundry machines and in particular to laundry washing machines having a spin basket and an independently rotating agitator within the spin basket. 
       SUMMARY OF THE PRIOR ART 
       [0002]    In 1991 Fisher &amp; Paykel Limited released the first model of their SMARTDRIVE washing machines. This machine included a cabinet, a tub suspended within the cabinet by a plurality of suspension rods extending between the top edge of the cabinet and a lower portion on the tub. A single shaft extended through the base of the tub. The stator of a salient pole electronically commutated brushless DC motor was fixed to the lower side of the tub base. An external permanent magnetic rotor was fitted to the lower end of the shaft to substantially surround the stator. Within the tub a spin basket was supported for rotation on the shaft. Within the spin basket an agitator was fixed to the upper end of the shaft. The agitator was of a central post type with three lateral vanes and a generally conical base portion. The spin basket was supported by the shaft at a lower position, was free to rise on the shaft to an upper position. The spin basket included downwardly facing hollow chambers. Vertical support of the spin basket on the shaft in the lower position included inter-engagement of a downwardly facing castellated clutch on the spin basket and an upwardly facing castellated clutch fixed to the shaft. Accordingly without sufficient wash liquid in the tub for the spin basket and any associated load to float the spin basket remained rotationally fixed to the shaft. With sufficient wash liquid in the tub the float chambers of the spin basket would provide for the basket and load to float and disengage from the shaft such that the spin basket and shaft would rotate. This arrangement is described in U.S. Pat. No. 5,353,613. This direct drive electronically controlled laundry machine has been very successful. A number of competing companies have sought to devise alternative arrangements for selectively transmitting power of the motor to the spin basket. 
         [0003]    U.S. Pat. No. 6,212,722 proposes an improved laundry washing machine for domestic use. This machine is of the top loading type having an outer bowl, a wash basket within the outer bowl and access to the wash basket through a top opening. A motor is provided to drive rotation of the wash basket within the outer bowl. A wash plate is provided in the lower portion of the wash basket to be rotated by the motor with the wash basket or independently of the wash basket. The patent proposes a combination of water level control, wash plate design, wash basket design and movement pattern for the wash plate which leads to an inverse toroidal movement of the laundry load during a wash phase. The sodden wash load is dragged radially inward on the upper surface of the wash plate and progresses upward in the region of the centre. The sodden wash load then progresses radially outward to the wall of the wash basket and downward to the base of the wash basket. This has been found to provide an effective wash action with low water consumption. 
         [0004]    When a wash system of the type disclosed in U.S. Pat. No. 6,212,722 is applied to a machine of the type described in U.S. Pat. No. 5,353,613, the water volume required to operate the floating clutch can be a significant factor in overall water consumption. 
         [0005]    U.S. Pat. No. 4,803,855,Kennedy, describes an agitate and spin drive for a washing machine. The mechanism includes a pair of concentric shafts extending through the lower wall of the wash tub. The upper end of the inner shaft is connected to drive the agitator. The upper end of the outer shaft is connected to drive the wash basket. A pulley at the lowest end of the inner shaft is driven by an electric motor. A lost motion mechanism or clutch in the form of a plurality of stacked disks is mounted on the agitator shaft. A lower end of the lost motion clutch is driven by the pulley. An upper end of the lost motion mechanism drives the lower end of the wash basket shaft. The lost motion clutch mechanism is located in the area between the base of the wash tub and the drive pulley. The overall arrangement requires both the wash basket shaft and agitator shaft to penetrate the wash tub. 
         [0006]    U.S. Pat. No. 2,273,566 illustrates a washing machine with an agitator housed within a wash basket. The wash basket includes a central hub 41 extending up inside the post of the agitator. A lost motion clutch acts between the inner surface of the agitator and the outer surface of the hub. The clutch allows less than one revolution of relative movement between the wash basket before the agitator begins to drive the wash basket. 
         [0007]    U.S. Pat. No. 2,609,697 describes a washing machine with an agitator housed within a wash basket. The wash basket is rotatably supported on the drive shaft. The agitator is fixed to the drive shaft. A downward extending lug on the agitator skirt is positioned to engage against an upward lug on the floor of the wash basket. The clutch allows less than one revolution of relative movement between the wash basket before the agitator begins to drive the wash basket. 
       SUMMARY OF THE INVENTION 
       [0008]    It is an object of the present invention to provide a laundry machine which goes some way toward overcoming the above disadvantages or which will at least provide the public with a useful choice. 
         [0009]    In a first aspect the invention consists in a laundry machine comprising:
       a tub,   a spin basket in said tub,   a drive assembly comprising a shaft and agitator, the shaft passing through a wall of the spin basket, said agitator being located within said spin basket,   a lost motion clutch physically located in the tub, interconnecting between the drive assembly and the spin basket and absorbing greater than one revolution of relative rotation.       
 
         [0014]    According to a further aspect of the invention clockwise rotation of said agitator relative to said spin basket ends at a first end condition wherein said drive assembly is engaged to drive said spin basket in a clockwise direction, and
       anticlockwise rotation of said agitator relative to said spin basket ends at a second end condition wherein said drive assembly is engaged to drive said spin basket in an anticlockwise direction, said first end condition and said second end condition being greater than one revolution of relative rotation between said agitator and said spin basket apart.       
 
         [0016]    According to a further aspect of the invention said lost motion clutch includes a rotation member mounted for rotation about said shaft, said rotation member having a first pair of stop surfaces, one facing clockwise and one facing anticlockwise, and a second pair of stop surfaces, one facing clockwise and one facing anticlockwise,
       said drive assembly has a pair of stop surfaces, one facing clockwise and one facing anticlockwise,   said spin basket has a pair of stop surfaces, one facing clockwise and one facing anticlockwise, and   in said first end condition said first pair clockwise surface engages against said drive assembly counter clockwise surface, said second pair anticlockwise surface engages against said spin basket clockwise surface, and   in said second end condition said first pair counter clockwise surface engages said drive assembly clockwise surface, and said second pair clockwise surface engages against said spin basket counter clockwise surface.       
 
         [0021]    According to a further aspect of the invention said rotation member includes a lug, with said clockwise facing surface of said first pair and of said second pair being on one side surface of said lug and said counter clockwise surface of said first pair and of said second pair being on another side surface of said lug. 
         [0022]    According to a further aspect of the invention said drive assembly includes a lug, and said pair of stop surfaces of said drive assembly comprise opposite faces of said lug. 
         [0023]    According to a further aspect of the invention said spin basket includes a lug, and said pair of stop surfaces comprise opposed faces of said spin basket lug. 
         [0024]    According to a further aspect of the invention said drive assembly lug and said spin basket lug do not share the same axial and radial position relative to the rotation, such that said lugs pass by one another with relative rotation of said agitator and said spin basket in the absence of any intervening clutch member. 
         [0025]    According to a further aspect of the invention said drive assembly lug and said spin basket lug overlap in the axial direction but are separated in the radial direction, and the radial extent of said lug of said rotating member overlaps with the outer of the drive assembly lug and the spin basket lug. 
         [0026]    According to a further aspect of the invention wherein there is a clearance of less than 10 mm between said drive assembly lug and said spin basket lug as said lugs pass each other with relative rotation of said agitator and said spin basket. 
         [0027]    According to a further aspect of the invention said drive assembly, but for said lost motion clutch, would be free to rotate relative to said spin basket. 
         [0028]    According to a further aspect of the invention said spin basket is supported for rotation at a fixed axial position on said shaft. 
         [0029]    According to a further aspect of the invention said shaft rotates around a vertical axis, and said tub and said spin basket are accessible through a top opening. 
         [0030]    According to a further aspect of the invention said shaft of said drive assembly protrudes from below a base portion of said tub, a stator of an electric motor is fixed to said tub, and a rotor of said electric motor is fixed to said shaft. 
         [0031]    According to a further aspect of the invention the laundry machine includes a cabinet, and a plurality of suspension members extending between an upper portion of said cabinet and a lower portion of said tub, said suspension members supporting said tub, spin basket, drive assembly and motor within said cabinet. 
         [0032]    According to a further aspect of the invention said motor is of the external rotor type. 
         [0033]    According to a further aspect of the invention said lost motion clutch includes a shock absorber for absorbing engagement impacts at one or both ends of the relative motion. 
         [0034]    According to a further aspect of the invention at least one said stop surface is elastically supported relative to the respective rotation member, drive assembly or spin basket. 
         [0035]    According to a further aspect of the invention said laundry machine includes a power supply circuit connected with windings of said motor, and a microcomputer having outputs connected to said power supply circuit for controlling the application of power to said windings of said motor, said microcomputer being programmed to drive said drive assembly in at least a first mode involving strokes of short duration in alternate directions, and a second mode involving continuous running for many revolutions in the same direction. 
         [0036]    According to a further aspect of the invention said microcomputer is programmed to limit the angular rotation of any single agitation stroke of said drive assembly to be less than about 1.5 revolutions. 
         [0037]    According to a further aspect of the invention said microcomputer is programmed to detect any occasional end condition that occurs during agitation and to terminate the drive of motor in that agitation stroke as soon as the collision is detected. 
         [0038]    According to a further aspect of the invention said microcomputer is programmed to monitor the load on the motor and detect said end condition by an increase in the motor load. 
         [0039]    According to a further aspect of the invention said microcomputer is programmed to detect any directional bias in any residual rotation of the spin basket during agitation. 
         [0040]    According to a further aspect of the invention said microcomputer is programmed to adjust the respective agitator stroke lengths to try to reduce this bias and preferably to reverse the estimated accumulated relative creep in one direction. 
         [0041]    A laundry machine comprising:
       a tub,   a spin basket in said tub,   a drive assembly comprising a shaft and agitator, the shaft passing through a wall of the spin basket, said agitator being located within said spin basket, and       
 
         [0045]    To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting. 
         [0046]    The term “comprising” as used in this specification means “consisting at least in part of”. When interpreting each statement in this specification that includes the term “comprising”, features other than that or those prefaced by the term may also be present. Related terms such as “comprise” and “comprises” are to be interpreted in the same manner. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0047]      FIG. 1  is a cutaway perspective view of a laundry machine according to a preferred embodiment of the present invention. 
           [0048]      FIG. 2  is a block diagram of a control system for a laundry washing machine. 
           [0049]      FIG. 3  is a cross-sectional side elevation of a lower part of the tub and spin basket, the agitator and an upper part of the drive shaft according to a preferred embodiment of the present invention. 
           [0050]      FIG. 4  is a perspective view of a rotating clutch member and spin basket support bush according to a preferred embodiment of the present invention. 
           [0051]      FIG. 5  is a cross-sectional plan view through line AA in  FIG. 3  of the components of  FIG. 4  and agitator end stop  300 . 
           [0052]      FIGS. 6A to 6D  show a sequence of cross-sectional plan views of the type illustrated in  FIG. 5  illustrating the range of freedom of relative movement between the spin basket and agitator. 
       
    
    
     DETAILED DESCRIPTION  
       [0053]    A laundry machine that may incorporate a clutch according to the present invention is illustrated in  FIG. 1 . The laundry machine includes a cabinet  100  with a lid  102  and a user console  104 . A controller  106  is located within the body of the user console. The controller  106  includes a power supply and a programmed microcontroller. The power supply receives power from the mains supply and supplies power to the microcontroller, to a power supply bridge for the electric motor and to ancillary devices within the machine such as a pump and valves. Delivery of power to the motor  114  and the ancillary devices is at the control of the microcontroller. The microcontroller receives inputs from a user interface on console  104 . 
         [0054]    A tub  120  is supported within the cabinet. The tub is preferably suspended from the upper edge of the cabinet, for example by suspension rods  121 . The tub may alternatively be supported from below or from the sides of the cabinet. A wash or drain pump is fitted to the lower portion of the tub. The pump is preferably located at a sump portion of the tub. 
         [0055]    A wash basket  122  is supported for rotation within the tub. Opening the lid  102  provides user access to an upper open end of the wash basket. 
         [0056]    An agitator  124  is mounted in the lower portion of the wash basket. The agitator may be of a central post type, with or without additional moving parts, such as augers, or of a wash plate type, such as illustrated in U.S. Pat. No. 6,212,722, or of a pulsator type, or of any other type having independent movement from wash basket  122 . The illustrated agitator is of wash plate type, intended for facilitating low water level wash exhibiting inverse toroidal rollover patterns. 
         [0057]    The improvements and adaptations of the present invention are preferably implemented in a laundry machine of a direct drive type with motor fixed directly to the lower end of a single drive shaft. However other drive systems involving for example gearbox or belts driving a single drive shaft may alternatively be used. 
         [0058]    A motor  114  below the tub directly drives single shaft  128 . The single shaft  128  extends through the lower face of the tub, where it is supported in a pair of bearings  130 . A seal  360  prevents water escaping the tub at the interface between the tub and shaft. 
         [0059]    The wash basket  122  is mounted on the shaft within the tub. The wash basket may typically comprise a base  132  and a perforated cylindrical skin  134 . The perforated cylindrical skin extends up from the base to define an open ended drum. The wash basket may include a balance ring at the upper edge of the cylindrical skin. 
         [0060]    The wash plate  124  is also fitted to the shaft, within the wash basket  122 . 
         [0061]    A clutch arrangement  142  is provided to enable the motor  114  to selectively drive either the wash plate  124  independently of the wash basket  122 , or drive the wash basket  122 . In driving the wash basket the motor may also drive the wash plate. Various mechanisms have been proposed to accomplish. this selective drive. The present invention relates to an improved mechanism which promotes low water consumption while retaining a drive assembly where a single shaft penetrates the tub  120 . This mechanism is described in detail below. 
         [0062]    The controller is part of a control system for coordinating the operations of the laundry machine. The control system is illustrated in the block diagram of  FIG. 2 . The controller includes a microcontroller  800 . The microcontroller may include a microcomputer and ancillary logic circuits and interfaces. The microcontroller receives user input commands on user interface  802 . The user interface may include, for example, a plurality of touch controls such as switches or buttons, or may include a touch screen, or may include rotary or linear selection devices. The microcontroller may include a display device  804  to provide feedback to a user. The display device may comprise a plurality of indicators, such as lights or LEDs, or may include a screen display. The display device  804  and the user interface  802  may be mounted to a single module incorporating the microcontroller. 
         [0063]    The microcontroller receives power from a power supply  806 . The microcontroller also controls power switches  808  applying power from supply  806  to drive motor  810 . The microcontroller controls further power switches  812  applying power from supply  806  to a pump  814 . The microcontroller also controls a power switch  830  applying power to a cold water inlet valve  832  and a power switch  834  applying power to hot water inlet valve  836 . 
         [0064]    The microcontroller preferably receives feedback from position sensors  816  associated with the motor. These sensors may for example be a set of digital Hall sensors, sensing changes in rotor position, or may be any suitable encoder. Alternatively rotor position and movement may be sensed from motor drive current or EMF induced in unenergised motor windings. 
         [0065]    The microcontroller also preferably receives input from a water level sensor  818 , which detects the level of water in the tub of the machine, and from a temperature sensor  820  which detects the temperature of water being supplied to the wash tub. 
         [0066]    The preferred controller applies an initial wash plate drive profile to initiate the inverse toroidal motion. The initial drive profile is characterised by higher angular velocity and longer stroke length to start the clothes movement. This movement is subsequently maintained by a maintenance drive profile with lower angular velocity and stroke length. Many drive systems are possible for controlling wash plate drive profiles. One example is described in U.S. Pat. No. 5,398,298. 
         [0067]    The initial drive profile is varied according to load size. The profile is more vigorous for larger load sizes. Load size may be determined from a user entry or selection, or by monitoring the inlet flow and recirculation pump activity, or by one of the many methods described in the prior art. 
         [0068]    Preferably the maintenance drive profile is also varied according to load size. Again the profile is more vigorous for larger load sizes. 
         [0069]    Acceptable wash performance is considered a compromise between achieving regular inverse toroidal turnover of a wash load within the spin basket and wear and tear associated with wash profiles that are too vigorous (and speeds that are too high) or entanglement (angular strokes that are too long). In general agitator wash strokes are between 0.5 revolutions and 1.5 revolutions. In each wash stroke the relative rotation between agitator and wash basket is generally less than 1.5 revolutions. 
         [0070]    According to the invention an improved clutch mechanism is disposed within the tub of the laundry machine. In the preferred embodiment illustrated in the drawings the mechanism is provided in the space between the wash plate  124  and the upper side of the base  322  of the spin basket. 
         [0071]    The spin basket is rotatably supported on the shaft  128 , for example by a pair of bearings  318 . The spin basket is vertically supported on the shaft  128 , for example by a thrust bearing  310 . 
         [0072]    The bearings  318  are fitted within bearing tube  320  of the base portion  322 . The bearings  318  are preferably of a sliding seal type. The bearings  318  provide radial support of the spin basket relative to the shaft. The bearings are vertically spaced on the shaft to provide torsional stability. 
         [0073]    The thrust bearing  310  is fitted to the shaft  128  above the upper radial bearing  318 . The thrust bearing  310  preferably engages over a spline  313 . The thrust bearing  310  has an upwardly facing thrust surface which supports the weight of the spin basket. The lower edge of the thrust bearing  310  is supported on a shoulder  317  of the shaft  128 . A support hub  308  tests on the thrusts surface of thrust bearing  310  and is secured to an upper face of the spin basket base  322 . A lower surface  332  of the support hub  308  bears on thrust surface  334  of thrust bearing  310 . 
         [0074]    A drive ring  302  is mounted to rotate around the axis of shaft  128 . The drive ring includes a drive lug  304  extending radially. 
         [0075]    An end stop  306  extends, preferably upwardly, from the outer surface of base  322  of the spin basket. An end stop  300  extends, preferably downwardly, from the underside of wash plate  124 . The end stop  306  and end stop  300  are positioned and configured such that they move past each other when the agitator rotates relative to the spin basket. In the illustrated arrangement the spin basket end stop  306  is radially inside the inner most extent of agitator end stop  300 . The end stops could alternatively be vertically separated, or have other non-interfering complementary shape and location. 
         [0076]    The drive lug  304  of drive ring  302  extends outwardly sufficient to interfere with both end stop  306  and end stop  300 . 
         [0077]    Either end stop may be in the form of a free standing lug. Alternatively the end stop may be an end portion of a ridge or other formation, so long as the end stops and the drive lug meet the interference requirements of the clutch. 
         [0078]    The agitator  124  is fixed to the upper end of drive shaft  128 . The agitator  124  rotates with drive shaft  128 . Typically the drive will operate in a wash mode where the shaft is reciprocated in alternate directions, and a continuous rotation mode in which the shaft is rotated for longer periods in a single direction. 
         [0079]    For the continuous rotation modes, the end stop  300  of the agitator drives around the drive lug  304  of drive ring  302  when it is rotating and in contact with the lug  304 . Lug  300  continues to drive around the drive lug  304  until drive lug  304  contacts the end stop  306  of the spin basket. Drive lug  304  then in turn drives rotation of the spin basket by end stop  306 . In this condition with rotation of the end stop  300  against lug  304  against end stop  306 , rotation of the drive shaft drives rotation of the agitator and spin basket together. 
         [0080]    From this drive position in a first direction the drive shaft may rotate relative to the spin basket through almost two full revolutions before meeting a second end condition where it drivingly engages the spin basket for rotation in the other direction. The agitator end stop  300  moves nearly one full revolution around the drive shaft  124  before engaging drive lug  304  on the same side as end stop  306 . End stop  300  continues to drive drive lug  304  for almost one further complete revolution before the opposite side of drive lug  304  engages against end stop  306  of the spin basket. At this point rotation of the agitator would proceed to drive rotation of the spin basket via the first end stop, drive lug  304  and second end stop  306 . However this point of rotation is nearly two full relative revolutions away from the other end condition, and so in a typical agitation stroke of up to 1.5 revolutions this condition is not reached. 
         [0081]    In the illustrated embodiment end stop  306  is an upwardly extending lug at the perimeter of support hub  308 . Support hub  308  includes a raised hub portion with an outwardly facing wall  338  and a perimeter flange  330 . The lug  306  extends upward at the periphery of perimeter flange  330 . The annular body  331  of drive ring  302  fits over the hub portion of the support hub  308 , occupying the region inward of lug  306 . Inner face  336  of ring  331  slides against outwardly facing surface  338  of support hub  308 . 
         [0082]    The support hub  308  is fixed to the upper face of the spin basket base  322 , for example by fasteners  312 . Practically, this allows assembly of the spin basket onto the drive shaft by first fitting the radial support bearings over the drive shaft, then fixing the thrust bearing  310  over the lower spline  313 , then support hub  308  is fitted over the drive shaft and fastened to the spin basket base to support the spin basket on thrust bearing  310 , then agitator  124  is fitted to the upper spline on the drive shaft and secured in place by fastener  350 . 
         [0083]    Typical agitator motion during the agitation mode is between 0.5 and 1.5 revolutions. So the almost two revolutions provided by the clutch of the present invention will generally be sufficient to absorb the agitation movement of the drive shaft without engaging to drive the wash basket at the end of each stroke. 
         [0084]    In the preferred electronically commutated drive system an upper limit can be applied to the agitator motion, for example an upper limit of 1.5 revolutions. 
         [0085]    However there may be a directional bias in the relative movement between the agitator and the wash basket. The wash basket will tend to be dragged by the action of the wash load acting as a viscous clutch between the wash plate and wash basket. This dragging action will tend to be compensated by a coast of the spin basket at the end of an agitation stroke. However a residual movement of up to about 20 degrees is observed. In any wash cycle or random part of a wash cycle the residual movement may exhibit a bias in one direction. This will result in the reciprocating agitation stroke operating further toward one end of the range of movement between end conditions. Eventually, and perhaps frequently under some conditions, the clutch will reach an end condition at the end of an agitator stroke. Thus at the end of occasional strokes the spin basket may be driven momentarily by the clutch at the end of the stroke. 
         [0086]    In the preferred electronically commutated drive system we propose to detect any such occasional end condition and to terminate the drive of motor in that agitation stoke as soon as the collision is detected. It is possible for the microcontroller to monitor the load on the motor with reasonable accuracy and frequency by monitoring, for example, the motor current. The end condition may be detected by an increase in the motor load. 
         [0087]    Further, in the preferred electronically commutated drive system we propose to detect any directional bias in the residual rotation of the spin basket. For example we may detect a difference in the motor load while driving the agitator in one direction compared to the other direction, and assume that this indicates greater dragging of the spin basket in the higher load direction. Or, for example, we may detect greater load at the point of reversal of the drive direction, which may indicating that the spin basket is coasting for longer into the new stroke direction. The respective agitator stroke lengths may then be adjusted to try to reduce this bias and preferably to reverse the estimated accumulated relative creep in one direction. 
         [0088]    Further, the clutch construction may be modified so that the impact at the end condition may be reduced. 
         [0089]    For example either end stop may be formed to be soft or springy. For example one end stop may have a buffer on each side, or each end stop may have a buffer on one side. The buffer may be a spring arrangement, preferably elastically absorbing the impact to release the energy in the new stroke direction. 
         [0090]    As a further example, the drive lug on the drive ting may be flexible, for example an outwardly extending leaf of spring steel, which may bend elastically with the impact between the end stops. 
         [0091]    As a less preferably example, either end stop may have a friction clutch engagement to the respective support part (the spin tub or the drive assembly). This is less preferred as the absorbed energy is dissipated as heat. It is expected that with the range of movement available and the control available in the electronically controlled drive system the any pick up at the end condition will be relatively light, and so an elastic shock absorber that returns energy to the system should be sufficient to absorb the impact. 
         [0092]    The drive arrangement according to the present invention allows driving of the agitator in alternate directions through a useful length of stroke with only a single shaft penetrating the tub, and without relying on water level for disengagement.