CA1329235C - Drive for clothes washing machines - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
An electric motor, a drive and a clothes washing machine including the motor and drive are described, the motor having a stator held outboard of a frame carrying bearings in which a shaft rotates, the shaft carrying the rotor outboard of the stator, the rotor having permanent magnets on an inner face thereof. The shaft carries an agitator and a spin tub of the clothes washing machine and interconnecting members between a part rotatable with the agitator and a part rotatable with the spin tub are movable axially on the shaft relative to each other by a buoyancy system which is operated by the absence or presence of water in a container of the clothes washing machine to connect the spin tub and the agitator to be driven by the shaft continuously in one direction for spinning clothes when water is at a low level in or absent from the container and to disconnect the spin tub from the shaft, leaving the agitator still connected to the shaft when sufficient water is in the container so that rotation of the shaft backwards and forwards by the motor washes clothes in the spin tub by backwards and forwards movement of the agitator.

Description

- OIV. II
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Th-is application is a division of application serial number 531,143 filed March 4, 1987.
This invention relates to clothes washing machines of the type having a cabinet in which an agitator is mounted on a vertical axis and is oscillated back and forth within a perforated spin tub which in turn is mounted within a water tight container, the spin tub and the agitator rotating continuously in one direction to give a spin action, said cabinet containing an electric motor and driving means for the agitator and spin tub and/or clothes washing machines incorporating such drives.
It is an object of the present invention to provide an electric motor of the type described which will at least provide the public with a useful choice.
Accordingly in one aspect the invention consists in an electric motor comprising an electric motor comprising, a stator carrying energizable windings on poles thereof, a rotor, a motor frame having a single pair of bearings mounted in a central disposition, said frame having stator locating means arranged to hold an outer cylindrical surface of said stator concentric with said bearings, and a single shaft rotatably mounted in said bearings and carrying said rotor wherein said rotor comprises a backing ring of a magnetic material, a series of permanent magnets spaced apart on an inner surface of ;

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said backing ring said backing ring and magnets being rotatable exteriorly of said stator windings, a hub mounted on said shaft, and a backing ring support holding ` inner faces of said permanent magnets concentric with said shaft.
In a still further aspect the invention consists in an electric motor comprising a stator formed as an annular helical yoke edgewise wound from a strip of magnetic material and having an inner face and an outer face, said strip having pole pieces formed integrally therewith, the pole pieces extending from one edge of said strip and said strip being edgewise wound whereby said pole pieces coincide in stacked groups to form a plurality of poles arranged at equally spaced intervals extending radially outwardly from the outer face of the yoke, energizable stator windings wound directly on said poles of said stator and adapted to be energized through an electronic commutation circuit, and a rotor mounted for rotation exteriorly of the relative to said stator, . said rotor comprising a backing ring of magnetic material and a series of permanent magnets held at spaced-apart intervals on an inner surface of said surface of said backing ring and opposing the poles of said stator.
To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the `:
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1329~33 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.
The invention consists in the foregoing and also envisages constructions of which are the following gives examples.
One preferred form of the invention will now be described with reference to the accompanying drawings, in which:
Figure 1 is a cross sectional elevation of a clothes washing machine constructed according to the invention, with some parts shown at 45 in plan to other parts, Figure 2 is an enlarged view part in cross section of a water container, spin tub, agitator, drive and electric motor, and Figures 3 and 4 are respectively a plan view and cross section of preferred motor frames incorporated in the invention in the preferred form, Figure 5 is a further enlarged view of a seal shaft and bearings being part of Figure 2, Figure 6 is a part cross section of an alternative embodiment of the invention.

132973a Flgure 7 ls a part cross sectlon of a further alternative embodiment of the inventlon, Figure 8 ls a scrap elevatlon at 45 to the view ln Figure 1, and Figure 9 ls a rear Yiew of a motor agltator forming part of the lnventlon.
Referring to the drawings, a clothes washing machine comprises a cabinet l of square cross section which has mounted in it an electric motor 2 constructed accordlng to the present invention as will be descrlbed further later.
A water container 3 is su~pended within the cabinet 1 by suspension rods 4 and sprlngs 5 and for example four springs and rods are provlded, and the motor and other mechanism are attached to the container 3. The springs are lS provided in the corners of the square cross section cabinet ; l accordlngly parts of the rod are shown in sectlonal view in Figure 8 which is at 45 to the other sectional ~iew of Figure 1. By water is meant washlng liquid, e.g. water and - detergent. Contained within the water contalner 3 there is a perforated spin tub 6 and within the spin tub is an agitator 7. An opening lid 9, shown only partlally is provided through which clothes may be inserted into the - container and within the spin tub 6 and the spin tub is partly balanced by upper balancing ring 10 shown only in the rear one side in Figure 1. The springs terminate in hooks 12 which engage in apertures`13 in the container base , .

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132g23tj moulding 29. The agltator 7 l~ mounted on a hollow drlve shaft 11 so as to rotate therewlth but Is slldable axlally thereon, The spin tub 6 ls coaxlally mounted on the shaft 11 so as to be rotatably and also ~lidable axlally thereon.
` S The motor 2 is constructed as follows. A rotor 15 has a backing ring 16 (Fig 2) and the backlng rlng is formed from a strip of magnetic material for example a slllcon steel alloy and the strip of steel ls colled on edge wlth adjacent surfaces lightly insulated and touching each other to provide a short hollow cylinder or annular helix.
Inslde the helix there is provided a series of magnets 17, the backing ring 16 being expanded sllghtly before being placed over the magnets placed in a mould. The magnets are permanent magnets of a material capable of being magnetlsed to a high flux ~alue e.g. Neodinium iron made by Magnaquench Inc. and the annulus and the magnets are held in place by a plastlcs member 18 which has a hub 1~, a dlsc or spoked connector portion 20, and substantlally cylindrlcal element 21, the member being moulded over the 2~ backing ring and magnets so as to maintain the inner faces of the magnets 17 concentric with the axis of the hub 16.
me stator 25 of the motor has a magnetic core whlch comprises a strip of magnetic material again preferably a silicon steel alloy or other low hysteresis steel which is preformed to provide spaced apart pole pieces and again this strip is formed by bending on edge to form an annular helix in the form of a hollow cylinder with the poles 8 ~..
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` 132923a formed by the stacked pole pieces polnting outwardly. As may be seen in Figure 9 the poles B are connected together by a narrow band 14 so that bending on edge i3 relatively easily effected. To provlde insulation for windlngs on the poles of the core a top lnsulatlng moulding 22 is placed on one Qlde of the poles and a bottom lnsulating mouldlng 23 placed on the opposlte side, meeting at a ~olnt llne 24 ~indings are placed on the mouldings wound around each hole and such windlngs 26 are effected on the poles dlrectly.
It ls preferable that the stator be wound ln a three phase star connected mode and the wlndlngs are made and connected using known techniques.
The stator 25 and the rotor 15 are mounted as will shortly be descrlbed.
15 - The water container 3 is preferably an in~ection moulding and the base 29 has motor support columns 30 preferably braced ~ith stiffening webs 31. These webs extend to the outer perimeter of the contalner 3 and are moulded integrally with the container.
The motor 2 includes two bearing frames 32 and 33 which comprise injection mouldings of a die cast metal or plastics material or preferably steel pressings or plastics material. Preferably the frames 32 and 33 are produced from the same mould or set of dies, thus enduring equality of dimensions between the two frames. The frames are carefully designed and made so that the bearing mouldings 21 and ~8 are concentrlc wlth locatlng plna or dlmple:l 34 ,,:

' . , 1329~3a and corresponding holeq 35 at the perlphery of the frames and wlth the external angle 36 ln whlch the lnner corner 37 of the stator 25 fits with an interference bit.
Stiffening depressions 49 are provlded to stlffen the frames and on assembly one frame ls assembled rotated 45 relative to the other frame to provlde correct matchlng of hole~ and dimples.
Bearings 38 and 39 fit in the bearing mountings 27 and 28 and the bearings are spaced apart by a spaclng tube 40 which encircles the drlve shaft 11. The hub 19 is fixed to the shaft 11 by a bolt 41 en8aging a nut 42 held in the hollow of the shaft 11 by the shaft 11 being swaged down to provide splines which engage corresponding spline spaces 42 in the hub 11. For transport purposes a further nut 43 holds the assembly ~upported by suspension rods and fixed to a cabinet member 44.
~ he spin tub 6 comprises a stainless steel perforated hollow cylinder 45 ~ixed to a plastics extruded base 46 e.g. by spinning the lower edge of the cylinder 45 on to the perlphery of the plastics base 46. If desired a lower balancing ring 47 is provlded and the balancing rings each comprise as a hollow ring with baffles and liquid container therein and the rings are each closed by an annular disc 48. One balancing ring preferably the ring 10 were found to give reasonable balance while spinning.
A plurality of bridges 50 are provided at spaced intervals with gaps between them and the bridges connect .

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the balancing ring 47 (if fitted) to an alr cha~ber in the form of a bell 51 havlng an open mouth directed downwardly and a tube 52 integral therewlth which surrounds the qhaft 11. A low friction plastics bearing 53 enables the plastics base 29 and consequently the spln tub 6 to rotate and slide axially on the drive shaft 11.
A series of downwardly directed dog clutch teeth 55 (Fig 2) of a high impact duty materlal e.g. a high lmpact duty plastics material are carried by a carrier 56 riveted screwed or otherwise fixed to the air chamber 51 e.g. by screws 57. A ring 60 carries coacting dog clutch teeth 61 also of a high impact duty material and the ring 60 is rotatable by and axially slidable on the drive shaft 11 e.g. by engagement of splines on the ring 60 with splines on the drive shaft 11. The agitator 7 has a bo~s 62 with inner splines 63 engaging outer splines 6~ on the ring 60 so that rotation of shaft 11 results in rotation of the teeth 61 and the agitator 7, and the boss 62 slides axially on the drive shaft 11 as may be seen by conforming the up position of elements on the left hand side of figures 1 and 2 with the 'down' position on the right hand side..
The air chamber 51 is designed to provide a flotation or buoyancy force resulting from the entrapment of air in the air tight air chamber 51 when water closes the perimeter of the lower edge of the air chamber 51. In the event that water enters the air chamber 57, e.g. because of turbulance during agitation, the lower face could be closed ~' '. '` ' ' ~': "

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off with a disc 54.
The buoyancy force is at least sufflcient to lift the ~pin tub 6, and the agitator 7 when a substantially predetermined volume of water is provided in the contalner 3, and the spin tub and agitator 7 is shown in the nup"
posit~on on the left hand side of Figures 1 and 3 and in the "down" position on the right hand side. When the spin tub 6 is in the up position, i.e. supported by floatation of the air chamber 51, the teeth 55 and the teeth 61 are disengaged from each other and the agitator may be rotated freely over any desired rotational movement independent of the spin tub 6. When water is absent or substantially absent from the container 3 the spin tub 6 sinks until the teeth 55 and 61 are engaged. The spin tub 6 and agitator will then be rotated as one unit and this rotation wlll be effected continuously in one direction to spln clothes in the spin tub to a drier condition in the known way. To assist in freeing frictional contact between the axially sliding parts during up and down movement of the spin tub during filling with, and emptying of water, control meana are provided controlling motor 2 to give a slow agitating action i.e. forward and reverse rotation over a s~all arc of movement. At each reversal the dogs will reverse contact and be free of each other for a short time due to clearances a~ between the dogs and spaces between the dogs.
To assist in fixing the spin tub against rotation ` dur~ng agitation, i.e. when the agitator is in the up _ g _ 13~9~3~
position, the upper edge 67 of the spin tub may contact a frictional surface 68 on the underQide of a top member 69 of the container 3.
The agitator 7 haq external blades 81 thereon which extend from the surface of both column 82 and the upper surface of an upper coned disc 83. There is a space 84 between the disc 83 and the upper surface 85 of the air chamber 51 this space may be divided with radial vanes (not shown) since the purpose of the space arrangement is to provide a centrifugai impeller. Such an lmpeller may be otherwise provided e.g. an independent centrifugal pump could be provided.
Outlet openings 86 are provided from the space 84 at or near the outer edge of the disc 83 the outer edge 87 of which is turned downwardly and operates ln close proximity to the inner edge of the balance ring 46. As a result of this construction a pumping action iq given, pumping water from the centre of column 82 from apertures 88 through space 84 below balance ring 46 to space 86 between the spin tub 6 and the container 3 and lint is restrained in this space before the water re-enters the spin tub through the holes 90. If desired a container may be mounted on the column 82 such container holding a clothes conditioner in the known way.
Electronic commutation equipment 65 is provided on an annular printed circuit board in an annular container 66 mounted below the stator 25 and the electronic commutation ~, ~ ?, ``::

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. , 1 equip~ent is preferably enclosed in a compound for protection and heat sinking, and is such as to enable the electric motor 2 to move in a backward and forward motion thus causing the shaft 11 to be oscillated backward and forth resulting in the agitator 7 being also rotated in a back and forth motion to give the well known washing motion. The electronic commutation equipment 65 is also arranged to drive the motor continuously to give a spin action, and to drive the spin tub with the agitator, the absence of water rom the container 3 results in engagement of teeth 55 and 61 as above described.
-. However~ when the agitator is preferably given a -slow agitation motion and the container 3 has water in it ; ~
~-3~ at least to a predetermined level the flotation force of air in air chamber 51 causes the air chamber spin tub and agitator to rise~ The teeth 55 are then raised out of .~
contact with the teeth 61 and the agitator may now move -~ independently of the spin tub and thus may be oscillated back and forth at a desired rate and over any desired angle of rotation to give a washing action without material movement of the spin tub.

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~ To provide seals between the drive shaft 11 and the ~;
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base 29 of the water contalner, a qhort cyllnder Or e.g.
steel 70 (Flg 50) ls flxed to the upper frame 32 by a screw 71 and a flange 72 holds the bearlng 38 ln place. The short cylinder 70 supports a seal 72 agalnqt the wall 73 of an apperture in the water contalner base 29 and a dlsc 74 holds a further seal 75 against the shaft 11, belng reinforced by a backing rlng 76. A played disc 77 holds a further seal 78 against the shaft 11 reinforced also by a spring 79, the flange 80 sltting withln a short cyllnder 81 integral with disc.
The seal 72, short cylinder 81 disc 74 and seal 75 are integral with each other and the played disc 77 seal 78 and flange 80 are integral with each other. Both unit~ are made of Neoprene or other known flexlble sealing material.
A pump 95 is provided for the purpose of drainlng the container 3 and the pump 95 is mounted directly about an opening 96 in a lower part of the container 3 and thus a single flexible tube can run from the pump outlet through the back o~ the cabinet to the user draln connectlon polnt.
~ 20 It is to be noted that the bearlngs 37 and 38 are a `~ slip fit on the drive tube 11 and tightening of the bolt 41 -~ and a cap 91 by a screw 92 clamps both bearings into position. Removal of the rotor securement screw 92 and the bolt 41 can result ln the drlve tube 11 being removed from above and the motor rotor 16 being removed from below. The motor 2 is removable as a unit after removing also the screws 93 holding the frames 32 and 33 ln posltion. Thus .
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for malntenance purposes thls removal can be readlly effected. Furthermore followlng removal of the securement screw 92, the agitator and aBitator hub can be removed and the spin tub assembly then lifted off from above. Thu9 maintenance is very simple.
It is alao to be noted that because the spin tub and its contents float during the agitation phase no thrust bearing is required. Also the bearing 53 operates under water and only under low speed condition i.e. the agitator speed relative to the substantially stationary spin tub and therefore the bearing need only be a light duty bearing.
An alternative form of interconnection means is provided as follows:
The agitator 7 has associated with it a bell 100 both ~eing fixed to the shaft 101 by a bolt 102. The shaft 101 corresponds to the shaft 11 and is driven by an electric motor as abo~e described.
, ~ithin the bell 100 is a rise and fall member 103 which ; is a plastics moulding sealably attached by a flexible bellows 105 eg. of neoprene to the outer edge 106 of the plastic member 103 and to the edge of the bell 100. A
further flexible bellows 107 is sealably attached to the member 103 and to the hub of the bell 100. The member 103 has prongs or dogs 108 spaced at intervals thereon and such prongs or dogs 108 engage in the spaces between castellations 109 in the bottom of the spin tub 6. A
~pring (not shown) is provided which exerts a downward - 1329~
force from the hub 108 on the member 103 and the cavlty 110 is open to atmosphere through a cros~ hole or notch 111 ln the hub 104 and a series Or holes ln the shaft or drlve tube 101. Thi~ arrangement is such that when the container 3 is emptyng, the spring moves the member 103 downwardly 50 that the prongs or dogs 108 engage in the spaces between the castellations and thus the spin tub wlll move with the agitator and be rotated with that agitator continuously for the purpose of spinning. However, when t.he container 3 has water in it to a predetermined level the hydrostatic water - pressure on the undersurface of the member 103 causes that member to rise against the pressure of the spring air venting through the air holes abovementioned and the prongs or dogs 108 are then raised out of contact with the spin tub and the agitator may now move indpendently of the spin tub and thus may be oscillated back and forth to give a ~ashing action.
In a further alternative arrangement of spin tub to agitator interconrecting means shown in figure 7 the agitator 7 is combined with a hub 110 fixed by a bolt 111 to a solid splined shaft 112. An air chamber in the form ` of a bell member 115 is a slideable fit on the shaft 112 and has air entrapment spaces 116 in which air is trapped by rising water in the container 3 when the latter is being filled preparatory to agitation occurring. The bell 115 then acts as a float raising detents or dogs 113 from engagement with castellations 107 as shown on the right 13~923~

hand ~lde of flgure 7 to a disengaged po31tlon as shown on the left hand slde of figure 7.
At least in the preferred forms the lnvention provldes the following advantages:
1. The electric motor assembly and construction is ntegrated with the drive system in that a slmple shaft and pair of bearings supports the rotor at one end of the agitator and spin tub at the other end advocating the need for separate shafts and bearings for the motor and for the agitator and spin tub drive~
2. The mounting of the stator and the rotor outboard of the lower motor frame enable ready replacement of the stator and/or rotor.
3. The mounting of the electronics in an annular disk associated with the stator of the motor reduces the length of interconnecting wiring and enables a compact factory wired unit to be provided.
` 4. The floating spin tub concept eliminates the need for springs bearings and enables ready maintenance to be carried out.
5. The complete freedom of the agitation to rotate through -` an unlimited angle of rotation during agitation enables any desired angle of rotation.

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Claims (7)

1. An electric motor for a clothes washing machine comprising:
a stator carrying energizable windings on poles thereof;
a rotor;
a motor mounting having a single pair of bearings mounted in a central disposition in said mounting, said mounting having stator locating means arranged to hold an outer cylindrical surface of said stator concentric with said bearings;
and a single shaft rotatably mounted in said bearings and carrying said rotor, and at least one bearing of said pair of bearings being spaced at a remote position relative to said stator; wherein said rotor comprises a backing ring of a magnetic material, a series of permanent magnets spaced apart on an inner surface of said backing ring, said backing ring and magnets being rotatable exteriorly of said stator windings, a hub mounted on said shaft, and a backing ring support holding inner faces of said permanent magnets concentric with said shaft.

2. An electric motor as claimed in claim 1 wherein said stator is disposed outboard of said mounting and said rotor has a connecting portion between said hub and said backing ring and said connecting portion is outboard of said stator.

3. An electric motor as claimed in claim 1 or 2 wherein said stator comprises an annular helix of a magnetic material, said helix having said poles integral therewith extending outwardly from the circumferential surface of the annulus, said annular helix being mounted on said stator locating means.

4. An electric motor as claimed in claim 1 or 2 wherein insulation to insulate said windings from said poles is provided and comprises a pair of mouldings, each said moulding being in the form of an annulus with insulation covering one part of each pole, there being a division intermediate of the thickness of each pole between the two mouldings.

5. An electric motor comprising:
a stator formed as an annular helical yoke edgewise wound from a strip of magnetic material and having an inner face and an outer face, said strip having pole pieces formed integrally therewith, the pole pieces extending from one edge of said strip and said strip being edgewise wound whereby said pole pieces coincide in stacked groups to form a plurality of poles arranged at equally spaced intervals extending radially outwardly from the outer face of the yoke;
energizable windings wound directly on said poles of said stator and adapted to be energized through an electric commutation circuit; and a rotor mounted for rotation exteriorly of and relative to said stator, said rotor comprising a backing ring of magnetic material and a series of permanent magnets held spaced-apart intervals on an inner surface of said backing ring and opposing the poles of said stator; a motor mounting having a single pair of spaced-apart bearings mounted in said mounting in a central disposition relative to said mounting, said mounting having stator locating means arranged to hold an outer cylindrical surface of said stator concentric with said bearings; and a single shaft rotatably mounted directly in said bearings and carrying said rotor, and at least one bearing of said pair of bearings being spaced at a remote position relative to said stator.

6. An electric motor as claimed in claim 5 wherein the inner face edge of said stator strip opposite the edge thereof from which said pole pieces extend is notched between adjacent poles so as to reduce the width of said stator strip whereby adjacent poles are connected by a narrow band of strip material.

7. An electric motor as claimed in claim 1, 2, 5 or 6 and further comprising insulated mouldings on said poles, said stator windings being would on said insulated mouldings.