GB2136285A - Levelling Arrangement - Google Patents

Abstract

An automatic levelling arrangement, more especially for stabilising washing machines, spin driers, or the like, on an uneven surface, comprises a pair of spaced members, e.g. wheels or feet, carried by a mounting fitted to the base of the machine so that the members provide supports for the machine on the surface, the members being capable of movement relative to the mounting so as to be displaceable towards and away from the machine and the arrangement incorporating means linking the support members in a manner such that displacement of a member in one direction results in a corresponding but opposite movement of the other member. In Fig. 2, wheels 2 are mounted in brackets 3 pivoted at 4 to a chassis 7 fixed to the machine base, the brackets being linked by a rod 11. In Fig. 6, wheels 22 are mounted at opposite ends and on opposite sides of a tube 24 rotatable in brackets 25 fixed to the machine base. <IMAGE>

Description

SPECIFICATION Levelling Arrangement This invention relates to automatic levelling arrangements for assisting in stabilising apparatus of the kind arranged to be supported at four points defining the corners of a quadrilateral, and which may be required to rest on an uneven surface, and relates especially, though not exclusively, to such arrangements for use on washing machines, spin dryers and like appliances.

According to the invention an automatic levelling arrangement comprises a pair of spaced members carried by a mounting which is arranged to be fitted to the base of apparatus required to be stabilised, so that the members provide adjacent supports for said apparatus on a supporting surface, the members being capable of movement relative to the mounting so as to be displaceable towards and away from the base of the apparatus, and the arrangement including means linking the support members in a manner such that displacement of a member in one direction results in a corresponding but opposite movement of the other member.

In use the support members of the levelling arrangement are conveniently arranged to be associated with two non-displaceable support members disposed at the other support points, the four support members being disposed beneath the apparatus they are arranged to support preferably in the form of an approximately rectangular array.

It will be seen that in apparatus incorporating such an arrangement each pair of diagonally opposite support members includes one forming part of the self-levelling arrangement.

Consequently if the apparatus is stood on an uneven surface, instead of rocking about two diagonally opposite support members, as would be the case if all the members were fixed in position, the weight of the apparatus will tend to cause the two members of the self-levelling arrangement to be displaced in opposite directions, so that they compensate wholly or partly for the unevenness, depending upon their range of movement.

Each displaceable support member may be carried by a separate carrier pivotable about a nominally horizontal axis when fitted to the apparatus in its normal operating position, the support members being spaced horizontally from the respective pivot axes, and the two carriers being linked by means which causes them to pivot in directions producing the required opposite displacement of the support members.

Thus each member may be carried by an arm of a respective bell crank lever pivotally mounted on a respective mounting member, with the other two arms of the levers interconnected in a manner such that, as the levers pivot about their axes, the support members are displaced in opposite directions towards and away from the apparatus respectively.

Preferably the bell crank levers are disposed with the arms carrying the support member directed towards each other and the other arms directed generally upwards, and interconnected by a relatively rigid link.

The support members are conveniently in the form of wheels rotatably carried by the bell crank levers with their axes of rotation parallel to the pivot axes of the levers.

Preferably means are provided for damping the pivoting movement of the bell crank levers. This measure serves to stabilise the apparatus against movement in use.

In an alternative arrangement the support members are mounted on opposite sides of an elongate carrier member, adjacent opposite ends thereof, the latter being supported by a mounting which is arranged to be fitted to the base of the apparatus so that the carrier member extends generally horizontally and is rotatable relative to the mounting about a longitudinal axis, the positions of the support members being such that on rotation of the carrier member one support member is displaced towards the apparatus and the other away from it.

The support members in this arrangement are also preferably in the form of wheels rotatable about parallel axes extending transverse to-the axis of the carrier, which is conveniently in the form of a cylindrical rod or tube.

The mounting may be provided by a pair of mounting members of bifurcated form with the two arms supporting the carrier member between them. Conveniently the inner surfaces of the arms of each mounting member are provided with part circular opposed grooves in which the carrier member is accommodated. Means may be provided for adjusting the pressure of the arms of the mounting members against the surface of the carrier, in order to vary its degree of freedom.

In an alternative arrangement the carrier may be rotatable in simple journals carried by spaced mounting members.

Two different embodiments of the invention will now be described by way of example with reference to Figures 1 to 6 of the accompanying schematic drawings, in which Figure 1 illustrates a front loader washing machine incorporating a self-levelling arrangement in accordance with the invention, Figure 2 illustrates a side view in diagrammatic form of one form of self-levelling arrangement, Figures 3 and 4 show a side view and plan view of part of the arrangement in more detail, and Figure 5 illustrates a perspective view from below, and Figure 6 an end view of an alternative form of self-levelling arrangement.

Referring to Figure 1 of the drawings, the first washing machine is contained within a cabinet C supported by four wheels 2, 2A adjacent the four corners of the cabinet base. The two wheels 2A on one side of the cabinet are carried by fixed supports secured to the cabinet base, whilst the two on the other side form part of an automatic self-levelling device in accordance with the invention. This is shown more clearly in Figures 2 to 4.

The self-levelling device comprises two similar units 1 each incorporating a respective wheel 2 rotatably mounted in an enclosing support bracket 3 pivotally mounted at one end 3a about a pin 4 which is secured to a mounting block 5 so that it extends parallel to the wheel axis. The mounting block is secured by means of a bolt 6 to the underside of a chassis member 7 at the base of the washing machine cabinet. Free movement of the support bracket 3 is restricted in operation by a 'U' shaped damper bracket 8 which overlies the non-pivoted end 3b of the support bracket and which in turn is also fixed by two screws 9 to the chassis 7.

The two downwardly extending sides 8a of the damper bracket 8 bear resiliently against the outer surfaces of the walls of the support bracket 3 so as to restrict free movement of the latter by frictional engagement. A downwardly protruding tongue 8b integrally formed with the damper carries a sleeve 10 which is positioned so as to be in rubbing contact with the inner surfaces of the bearing bracket walls to counter the inward pressure of the sides 8a of the damper bracket 3.

Restriction of the bracket movement serves to stabilise the machine against undue movement when in use, and is not concerned with the self levelling function of the arrangement.

A similar self-levelling unit 1 is mounted in the other corner at the same side of the washing machine in such manner that the two wheel support bracket pivot points are mounted at the extremities of each corner, i.e. providing for optimum stabilisation in use. The two units are linked by a rod 1 1 which has in-turned ends 1 a pivotally supported in suitable holes provided in an upwardly extending limb 3c of each of the two brackets 3. Suitable retention means, such as a self-securing washer 12, is provided for the ends of the rod 11. The disposition of the limbs 3c and the length of the rod 1 1 is such that from the normal position (shown in the drawing) each support unit is able to move in an equal and opposite way to the other.Thus, for example, if one of the units moves in a downwards direction its support bracket limb moves inboard carrying with it the rod 1 1 which in turn displaces the other support bracket limb, moving the bracket and its wheel in an upward direction by a corresponding amount.

Considering the operation of the self-levelling arrangement for the machine as a whole, if an unevenness, e.g. a local depression were to be present in the floor such that normally the wheel at that point would drop into the recess and thus cause the machine to rock about the two adjacent diagonally opposite wheels; one of the two diagonally opposite wheels would be associated with the self-levelling arrangement and this would move upwardly thereby moving the other selflevelling wheel downwardly until a stable situation, as regards all wheels, is achieved.A suitable level of damping of the support units to effect, on the one hand stabilisation of the machine in operation (as has already been mentioned) and on the other hand relatively free movement of the self-levelling units to enable a stable situation for any particular machine incorporating the self-levelling arrangement can readily be determined.

Whilst this embodiment of the invention is mainly concerned with self-levelling arrangements for machines supported on wheels, it could also be employed on machines having feet in place of the wheels, the underside of the feet of the self-levelling arrangement preferably being of radiused shape so that they present a similar surface to the floor in all positions of their range of movement.

The second washing machine has a cabinet similarly supported by four wheels, the two on one side of which also form part of a self-levelling arrangement and act together to compensate for a degree of unevenness in the floor surface. The self-levelling arrangement in this case, which is shown diagrammatically in Figures 5 and 6 has each wheel 22 pivotally mounted about a pin 23 secured to a support tube 24 rotatable within two spaced apart mounting brackets 25 each of which is secured to the underside or chassis 26 of the washing machine cabinet C, the wheels being mounted on diametrically opposite sides of the tube 24.

The mounting brackets 25 are each of bifurcated shape the two downwardly projecting limbs 25B of which are formed with opposed part-cylindrical grooves which accommodate the support tube 24 as shown.

In operation of the self-levelling arrangement, when compensation for unevenness in floor surface is needed, thus requiring one of the two self-levelling wheels to move upwardly-in this arrangement in a rotational sense because of its supporting tube 24 being rotatably mounted-the wheel at the other end of the tube is caused to move in a similar manner, but-in a downward direction, by a corresponding amount until a stable situation of the wheeled arrangement is achieved.

It will be noted that because the wheels move upwardly and downwardly through a curved path, contact of the-peripheral surface of each wheel, other than in a normal, i.e. level condition, will tend, by an increasing amount, to one side or the other as the wheel tilts as indicated by the broken lines 22A in Figure 6. Although such tilting will not materially affect the wheel in its normal rotational sense, i.e. enabling movement of the machine on a floor, it may be necessary to provide radiused edges 27, as shown to assist movement.

This arrangement enables a very simple and cheap method of self-levelling to be achieved.

Moreover, as in this arrangement previously described it can be adopted for use with supporting feet rather than wheels to give a similar self-levelling facility. The self-levelling feet would in a similar manner need to have a domed or otherwise radiused under surface in order to facilitate adequate floor contact as the feet move upwardly or downwardly in a curved path.

This arrangement has the advantage that the axis about which the wheels pivot to effect the self-levelling function is perpendicular to their axis of rotation, which effectively avoids overcompensation during operation of the machine, and assists in stabilising it without the need to restrict movement of the tube 4 within the brackets 25. Consequently the bearing brackets 25 could alternatively be replaced by simple journal supports in which the tube is freely rotatable up to the extent of movement of the wheels. However in some cases it may be desirable to restrict freedom of movement of the support tube 24, and this can be effected in the arrangement illustrated by adjustably clamping the bearing brackets 25 about the tube by means (not shown such as a screw linking the two limbs 25B of the bracket adjacent to the opening 25A at their free ends.

Although the invention is mainly concerned with washing machines and especially combined washing machine/spin dryers it can also have application to other forms of apparatus which may need to be automatically stabilised on an uneven surface.

The invention includes within its scope washing machines and other apparatus incorporating self-levelling arrangements as above described.

Claims (14)

1. An automatic levelling arrangement of the kind referred to comprising a pair of spaced members carried by a mounting which is arranged to be fitted to the base of apparatus required to be stabilised, so that the members provide adjacent supports for said apparatus on a supporting surface, the members being capable of movement relative to the mounting so as to be displaceable towards and away from the base of the apparatus, and the arrangement including means linking the support members in a manner such that displacement of a member in one direction results in a corresponding but opposite movement of the other member.

2. An arrangement according to Claim 1 wherein the support members are associated in use with two non-displaceable support members disposed at the other support points, the four support members being disposed beneath the apparatus they are arranged to support in the form of an approximately rectangular array.

3. An arrangement according to Claim 1 or 2 wherein each displaceable support member is carried by a separate carrier pivotable about a nominally horizontal axis when fitted to the apparatus in its normal operating position, the support members being spaced horizontally from the respective pivot axes, and the two carriers being linked by means which causes them to pivot in directions producing the required opposite displacement of the support members.

4. An arrangement according to claim 3 wherein each displaceable support member is carried by an arm of a respective bell crank lever pivotally mounted on a respective mounting member, with the other two arms of the levers interconnected in a manner such that, as the levers pivot about their axes, the support members are displaced in opposite directions towards and away from the apparatus respectively.

5. An arrangement according to Claim 4 wherein the bell crank levers are disposed with the arms carrying the support member directed towards each other and the other arms directed generally upwards, and interconnected by a relatively rigid link.

6. An arrangement according to Claim 5 wherein the support members are in the form of wheels rotatably carried by the bell crank levers with their axes of rotation parallel to the. pivot axes of the levers.

7. An arrangement according to any one of Claims 4, 5 or 6 including means for damping the pivoting movement of the bell crank levers.

8. An arrangement according to Claim 1 or 2 wherein the displaceable support members are mounted on opposite sides of an elongate carrier member, adjacent opposite ends thereof, the latter being supported by a mounting which is arranged to be fitted to the base of the apparatus so that the carrier member extends generally horizontally and is rotatable relative to the mounting about a longitudinal axis, the positions of the support members being such that on rotation of the carrier member one support member is displaced towards the aljpa ratus-and the other away from it.

9. An arrangement according to Claim 8 wherein the displaceable support members are in the form of wheels rotatable about parallel axes extending transverse to the axis of the carrier.

10. An arrangement according to Claim 8 or 9 wherein the mounting is provided by a pair of mounting members of bifurcated form with the two arms rotatably supporting the carrier member between them.

1 An arrangement according to Claim 10 wherein the inner surfaces of the arms of each mounting member are provided with part circular opposed grooves in which the carrier member is accommodated.

12. An arrangement according to Claim 10 or 1 1 including means for adjusting the pressure of the arms of the mounting members against the surface of the carrier, in order to vary its degree of freedom.

13. An automatic levelling arrangement substantially as shown in and as hereinbefore described with reference to Figures 2 to 4 or Figures 5 and 6 of the accompanying drawings.

14. A washing machine or a spin dryer or a combined washing machine/spin dryer having a levelling arrangement according to any preceding Claim.