GB2592265A

GB2592265A - Laundry appliance with self-balancing drum assembly

Info

Publication number: GB2592265A
Application number: GB2002546.6A
Authority: GB
Inventors: Herbert Grahame
Original assignee: Ebac Ltd
Current assignee: Ebac Ltd
Priority date: 2020-02-24
Filing date: 2020-02-24
Publication date: 2021-08-25
Anticipated expiration: 2040-02-24
Also published as: GB2592265B; GB202002546D0

Abstract

A washing machine has a fixed tub 1 with an outer drum 2 mounted rotatably therein. A perforated inner drum 3 is mounted rotatably within the outer drum, and a water-filled torus 4 with a flexible wall is located between the inner and outer drums. The inner drum 3 can move laterally within the outer drum relative to the rotation axis. A permeable layer 6 between the torus and inner drum provides drainage means. The outer drum may have a rear wall (22, Figure 3) that attaches to a drive shaft, and may be rotatably supported by wheels or rollers. The drive shaft may pass through bearings in a rear wall 12 of the tub 1 and be driven by a motor. The torus may have straight inner and outer walls (41, 42, Figure 2) connected by curved end walls (43, 44, Figure 2), and may be connected to a water supply by a rotating pipe via a sealed slip coupling with an automatic supply valve. The permeable layer may be cylindrical with open ends, formed by fabric or mesh.

Description

Intellectual Property Office Application No. GB2002546.6 Rum Date:3 August 2020 The following terms are registered trade marks and should be read as such wherever they occur in this document: Coruba (page 7) Intellectual Property Office is an operating name of the Patent Office www.gov.uk/ipo -1 -

LAUNDRY APPLIANCE WITH

SELF-BALANCNG DRUM ASSEMBLY

TECHNICAL FIELD OF THE INVENTION

This invention relates to laundry appliances, and more particularly washing machines.

BACKGROUND

Washing machines typically use centrifugal force to remove excess water from laundry at the completion of a wash cycle. A tub is non-rotatably mounted in a cabinet to contain water and a perforated drum is rotatably mounted in the tub. The drum is driven by a motor mounted at the rear of the tub. Laundry is placed into the drum through a front door of the washing machine. At the end of a wash cycle the drum is spun at high speed so that excess water is removed from the laundry, passing through the drum perforations, and is then conducted away via a tub drainage outlet. The tub is typically suspended by springs and dampers which are intended to attenuate vibrations generated by rotation of the drum, but despite these attenuation measures excessive vibrations may still occur due to the weight of the wet laundry -2 -being unevenly distributed around the drum. No matter how well a washing machine is set up vibration is almost always audible. In worst cases the sound may be amplified by suspended floors, or the vibrations could cause the machine to travel across the floor.

The prior art has various proposals for reducing such vibrations. For example, DE 2 746 989-A proposes that an annulus is fixed to turn with the drum on the same horizontal axis. The annulus is part-filled with liquid, and is fitted with a porous material to slow down the liquid movements. At high speeds, the liquid gathers on the opposite of the drum to the clothes, and brings it into balance. The annulus may be attached directly to the drum, or it may be on a separate disc, outside the tub but fitted on the drum axle and turning with the drum. Other known proposals include using an annulus containing balls. However, all of these proposals suffer from the disadvantage that they take a while to achieve balance resulting in substantial vibration at the beginning of a spin cycle. Furthermore, changes in rotational speed or the distribution of the laundry during a spin cycle can result in a transitional increase in vibrations until equilibrium is re-estabished.

SUMMARY OF THE INVENTION

When viewed from one aspect the present invention proposes a drum assembly for a laundry appliance: - a fixed tub (1) to contain water; - an outer drum (2) mounted in the tub for rotation about an axis; -3 - - a perforated inner drum (3) mounted within the outer drum and rotatable therewith; - a torus (4) interposed between the outer drum and the perforated inner drum, said torus having a flexible wall and being filled with liquid (5), wherein the perforated inner drum can move laterally within the outer drum relative to said axis of rotation; - a permeable layer (6) providing drainage passages between the torus and the perforated inner drum.

The invention also provides a drum assembly wherein the outer drum is rotatably supported within the fixed tub by guide wheels or rollers.

The invention also provides a drum assembly wherein the outer drum has a rear wall (22) to which a rear drive shaft is secured.

The invention also provides a drum assembly wherein the drive shaft passes through bearings in a rear wall (12) of the fixed tub.

The invention also provides a drum assembly wherein the drive shaft is driven by a motor mounted at the rear of the fixed tub.

The invention also provides a drum assembly wherein the torus has straight inner and outer walls (41 and 42) connected by curved end walls (43 and 44).

The invention also provides a drum assembly wherein the permeable layer is substantially cylindrical with both ends -4 -remaining open.

The invention also provides a drum assembly wherein the permeable layer is formed from a loosely woven fabric or corrugated mesh formed of natural or synthetic fibres, stainless steel or the like.

The invention also provides a drum assembly wherein the permeable layer is provided by corrugations in the wall of the inner drum forming axial drainage passages between the inner drum and the torus.

The invention also provides a drum assembly wherein the inner drum has a perforated cylindrical side wall (31) which is closed by a rear wall (32).

The invention also provides a drum assembly wherein the inner drum is formed in three or more sections such that the inner drum can be dis-assembled.

The invention also provides a drum assembly wherein the fixed tub is rigidly mounted without springs or dampers.

The invention also provides a drum assembly wherein the torus is connected to a water supply to maintain the amount of liquid therein.

The invention also provides a drum assembly wherein the water -5 -supply feeds the torus through a fixed pipe and a rotating pipe via a sealed slip coupling.

The invention also provides a drum assembly wherein the water supply feeds the torus via an automatic supply valve.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice. In the drawings: Figure 1 is a transverse cross sectional view of a drum assembly for a laundry appliance; Figure 2 is an exploded general view of the drum assembly Figure 3 is a front-rear vertical section through a laundry machine embodying a modified form of the drum assembly.

DETAILED DESCRIPTION OF THE DRAWINGS

The drum assembly to be described is typically installed within the -6 -outer cabinet of a laundry appliance such as a drum-type front-loading washing machine. Referring to Fig. 1, the apparatus includes a fixed (non-rotatable) tub 1 within which an outer drum 2 is rotatably mounted along with a perforated inner drum 3. Between the outer drum 2 and the perforated inner drum 3 is a torus 4, formed of rubber or similar flexible material, which is filled with a liquid 5, e.g. water. The torus 4 is separated from the perforated inner drum 3 by a layer of liquid-permeable material 6.

Considering the exploded view of Fig. 2 in greater detail, the tub 1 has a generally cylindrical side wall 11 which is closed at one end by a rear wall 12. The opposite end of the tub is sealably closed by the usual access door (not shown) at the front of the washing machine. The tub carries an array of wheels or rollers 13 which rotatably support the outer drum 2. The rollers may, for example, be mounted in indentations of the wall 11 to prevent water loss. This tub 1 may be mounted in the cabinet of a washing machine without springs and dampers, which thus simplifies both the mounting and the door sealing arrangement, although springs and dampers can be included if desired. The tub is also provided with the usual water inlet and outlet connections (not shown).

The outer drum 2 has a cylindrical side wall 21 and a rear wall 22 to which a rear drive shaft is secured enabling the drum to rotate about a central axis A. The drive shaft passes through bearings in the centre of the rear wall 12 to be driven by a motor mounted at the rear of the tub 1. The outer drum 2 contains suitably -7 -positioned apertures to ensure that water cannot accumulate therein. The outer drum also supports the outer surface of the torus 4.

The torus 4 is of generally cylindrical shape. In cross-section the torus has straight inner and outer walls 41 and 42 connected by curved end walls 43 and 44. The torus is completely sealed to contain the liquid 5, preferably without air spaces which would be subject to compression. Various abrasion resistant natural or synthetic rubbers are suitable for the torus material, for example Coruba 155 Red. The torus 4 rotates with the inner and outer drums 3 and 2. It should be noted that although a single torus is described it would also be possible to substitute two or more axially-arranged toruses, which would provide continuity of operation in the event of a possible puncture.

The liquid-permeable layer 6 supports the inner wall of the torus 4 and provides a drainage space between the perforated inner drum 3 and the impermeable torus. The layer may be substantially cylindrical with both ends remaining open. This could be a separate layer formed from a loosely woven fabric or corrugated mesh formed of natural or synthetic fibres, stainless steel or the like. It should also be noted that the liquid-permeable layer could also be provided by corrugating the wall of the inner drum to provide axial drainage passages between the inner drum and the torus.

The perforated inner drum 3 floats freely within the motor-driven -8 -outer drum 2 allowing the inner drum to move laterally relative to the axis of rotation A. The drum 3 has a perforated cylindrical side wall 31 which is closed by a rear wall 32, which may be continuous or perforated. To ensure that the inner and outer drums rotate together without stressing the torus 4 or the liquid-permeable layer 6 the two drums may be coupled together by flexible straps, springs etc. For ease of assembly and dis-assembly the inner drum may be formed in three or more sections, which facilitates servicing and replacement of the torus 4 if required.

Laundry is loaded into the open front end of the inner drum 3 through the door of the washing machine. At the end of a washing cycle the wet articles may tend to settle towards the bottom of the drum producing a downward pressure on the torus 4. This causes fluid 5 to flow towards the upper part of the torus so that the weight of the wet items is at least partly balanced by the extra weight of fluid on the opposite side of the drum even before the spin cycle commences. Thus, the apparatus is in better balance at the start of a spin cycle. This action continues throughout the spin cycle with flow of water around the torus (Fig. 1) automatically compensating for any changes in the load distribution. As water leaves the laundry under centrifugal force it flows through the side wall 31 of the perforated drum 3 and, upon meeting the impermeable torus 4, travels through the permeable layer 6 towards the ends of the outer drum 2. Upon entering the fixed tub 1 the water is conducted to waste as normal.

The laundry apparatus therefore allows the spin cycle vibrations to -9 -be substantially reduced throughout a spin cycle. Furthermore, since the outer rotating drum 2 is better supported by the rollers 13 and fixed tub 1 the weight bearing ability of the drum assembly is improved.

To cope with a typical full load the torus 4 generally needs to contain approximately 6 litres of water. An overall weight reduction of the machine could be achieved by making provision for the torus to be drained during transportation and re-filled in situ. Fig. 3 shows a laundry appliance with a modified drum assembly which allows the machine to be transported and installed in a dry condition. The laundry appliance is a drum-type front-loading washing machine having an outer cabinet 71 with a front door 72 providing access to the inner drum assembly which, whilst being similar to the assembly already described in most respects, has modifications which are explained below. The drum assembly includes a fixed (non-rotatable) tub 1 which may be mounted in the cabinet 71 without springs and dampers, although these can be included if desired. The tub is also provided with the usual water inlet connection (not shown) and a water outlet connection 77. Within the tub 1 an outer drum 2 and a perforated inner drum 3 are rotatably mounted. Between the outer drum 2 and the perforated inner drum 3 is a torus 4, formed of rubber or similar flexible material, which is filled with a liquid 5, e.g. water. The torus 4 is separated from the perforated inner drum 3 by a layer of liquid-permeable material 6. Essentially these components of the drum assembly are as described in relation to Fig. 2. The tub 1 has a rear wall 12 at one end and an opposite -10 -end which is closed by the access door 72 with an interposed flexible door seal 73. The tub has internal front and rear circular diecast metal running tracks 74 and 75 upon which the outer drum 2 is rotatably supported by wheels or rollers 76.

The inner drum 3 may be open at both ends, as shown. The rear wall 22 of the outer drum 2 is secured to a rear drive shaft 80 enabling the drum to rotate about a central axis A. The drive shaft passes through bearings 81 in the centre of the rear wall 12 and is driven by a motor 82 via a drive belt 83. The perforated inner drum 3 floats freely within the motor-driven outer drum 2 allowing the inner drum to move laterally relative to the axis of rotation A. To ensure that the inner and outer drums rotate together without stressing the torus 4 or liquid-permeable layer 6 the two drums may be coupled together by flexible straps, springs etc. The torus 4 rotates with the inner and outer drums 3 and 2, separated from the inner drum 3 by the liquid-permeable layer 6. The torus is automatically filled with water when the washing machine is connected to a water supply via a supply connection 86. The supply passes through a fixed pipe 87 and a sealed slip coupling 88, co-axial with the axle 80, leading to a rotating pipe 89 which rotates with the inner and outer drums to supply the torus 4 with water. A sensor 90 incorporating a supply valve controls the supply of water to the torus ensuring that the supply is cut off when the water level reaches the top of the torus 4. The sensor also allows automatic topping up of the water within the torus when required.

The operation of the drum assembly is as described above in relation to Fig.s 1 and 2, allowing spin cycle vibrations to be substantially reduced throughout a spin cycle. Again, since the outer rotating drum 2 is better supported by the rollers 79 and the fixed tub 1 the weight bearing ability of the drum assembly is significantly improved.

It will be appreciated that by establishing an appropriate design and specification of materials the torus can achieve the amount of stretch required to permit optimum movement of water around the drum assembly to permit rapid re-balancing of the drum assembly in response to redistribution of the load. The arrangement described is capable or partially or totally eliminating the dead weight of the load which normally occurs during the spin cycle of laundry appliances. With suitable selection of materials, and design for ease of replacement, a long and reliable service life is readily achievable.

Whilst the above description places emphasis on the areas which are believed to be new and addresses specific problems which have been identified, it is intended that the features disclosed herein may be used in any combination which is capable of providing a new and useful advance in the art.

Claims

-12 -CLAIMS1. A drum assembly for a laundry appliance: - a fixed tub (1) to contain water; - an outer drum (2) mounted in the tub for rotation about an axis; - a perforated inner drum (3) mounted within the outer drum and rotatable therewith; - a torus (4) interposed between the outer drum and the perforated inner drum, said torus having a flexible wall and being filled with liquid (5), wherein the perforated inner drum can move laterally within the outer drum relative to said axis of rotation; - a permeable layer (6) providing drainage passages between the torus and the perforated inner drum.
2. A drum assembly according to claim 1 wherein the outer drum is rotatably supported within the fixed tub by guide wheels or rollers.
3. A drum assembly according to claim 1 or 2 wherein the outer drum has a rear wall (22) to which a rear drive shaft is secured.
4. A drum assembly according to claim 3 wherein the drive shaft passes through bearings in a rear wall (12) of the fixed tub.
5. A drum assembly according to claim 3 or 4 wherein the drive shaft is driven by a motor mounted at the rear of the fixed -13 -tub.
6. A drum assembly according to any preceding claim wherein the torus has straight inner and outer walls (41 and 42) connected by curved end walls (43 and 44).
7. A drum assembly according to any preceding claim wherein the permeable layer is substantially cylindrical with both ends remaining open.
8. A drum assembly according to any preceding claim wherein the permeable layer is formed from a loosely woven fabric or corrugated mesh formed of natural or synthetic fibres, stainless steel or the like.
9. A drum assembly according to any of claims 1 to 7 wherein the permeable layer is provided by corrugations in the wall of the inner drum forming axial drainage passages between the inner drum and the torus.
10. A drum assembly according to any preceding claim wherein the inner drum has a perforated cylindrical side wall (31) which is closed by a rear wall (32).
11. A drum assembly according to any preceding claim wherein the inner drum is formed in three or more sections such that the inner drum can be dis-assembled.
-14 - 12. A drum assembly according to any preceding claim wherein the fixed tub is rigidly mounted without springs or dampers.
13. A drum assembly according to any preceding claim wherein the torus is connected to a water supply to maintain the amount of liquid therein.
14. A drum assembly according to claim 13 wherein the water supply feeds the torus through a fixed pipe and a rotating pipe via a sealed slip coupling.
15. A drum assembly according to claim 13 wherein the water supply feeds the torus via an automatic supply valve.