GB2158146A

GB2158146A - Interlock mechanism

Info

Publication number: GB2158146A
Application number: GB08510707A
Authority: GB
Inventors: John Edward Maggs
Original assignee: Hotpoint Ltd
Current assignee: Hotpoint Ltd
Priority date: 1984-04-27
Filing date: 1985-04-26
Publication date: 1985-11-06
Also published as: GB8510707D0; GB8410796D0; GB2158146B

Abstract

A catch mechanism especially for securing a washing machine door in the closed position, has a catch element 1 and a latch assembly 13, the latter comprising two separately moving elements. one of which 160 has a locking position in which it engages the catch element and a stop 16 which holds the latch element in the locking position, the other latch element being displaced by the catch element so as to compress a spring acting between the latch elements. The mechanism also includes means for releasing the first latch element from the stop so as to allow it to be moved from the locking position by the spring to release the catch. The mechanism is especially applicable to touch- release doors, and preferably includes an interlock for preventing the release of the door when it would be unsafe or inconvenient for it to be opened. <IMAGE>

Description

SPECIFICATION Interlock mechanism This invention relates to catch mechanisms for securing a member against withdrawal from an engaged position relative to another, but which is capable of actuation to permit such withdrawal, and relates especially, though not exclusively, to a mechanism for securing a door, especially of electrical apparatus, in the closed position. The invention has particular application, for example, to catch mechanisms embodying an interlock arrangement for preventing the opening of such a door when, for reasons of safety or otherwise, it would be inadvisable to do so.Such catch interlock mechanisms are commonly employed on washing and/or drying machines of the kind having a door which closes an access port for loading clothes into and removing them from a rotatable drum, as it is desirable to ensure that access to the drum cannot take place under certain conditions, for example when the drum is rotating.

One object of the present invention is to provide a form of catch interlock mechanism suitable for such a purpose. Another object of the invention is to provide a catch mechanism which provides a touch release. By "touch release" is meant the operation of opening and closing a hinged member such as a door or lid, hereinafter referred to simply as 'door' merely by applying light pressure to an area of the door close to the catch mechanism.

Thus when the door is open, such pressure causes it to move into the closed position, thereby allowing the catch mechanism to engage and hold the door closed, whilst, with the door closed, the pressure actuates the release mechanism of the catch to allow the door to open. No knob, handle or other form of manually operated device is thus needed to effect the opening or closing operation. Touch release mechanisms for doors are, in fact, already known, but a further object of the invention is to provide a form of touch release catch mechanism suitable for use in washing machines.

According to one aspect of the invention a catch mechanism for securing a member against withdrawal from an engaged position relative to another, but capable of actuation to permit such withdrawal, comprises a catch element carried by one said member and a latch assembly carried by the other member, the latch assembly comprising a pair of separately movable elements one of which, in the engaged position of the members, has a locking position in which it engages the catch element in a manner which prevents said withdrawal, and has associated with it a stop which holds said latch element in the locking position, the other latch element, in the engaged position of the members, being displaced by the catch element so as to compress a spring acting between the two latch elements, the mechanism also including means operable to release the first latch element from the stop means so as to allow the element to be urged away from the locking position by said spring and thereby enable the catch element to be withdrawn, and the mechanism including also further spring means operable to return both latch elements to their initial positions so as again to prevent withdrawal of the catch element when the two members are re-engaged.

The catch element is itself conveniently pivotally supported by the respective member, and is biased into a locking position in which it is engageable by the latch elements when the two members are engaged, and has a cam surface which produces a pivoting movement of the catch element against said bias to allow the members to be moved into the engaged position, the catch element being returned to the locking position under said bias when the members are fully engaged.

The catch element may be biased into the locking position by spring means or by gravity.

As applied to touch release catch mechanism for a door, the door is preferably urged towards the open position by compression of a spring, resilient gasket or the like when fully closed, the opening being prevented by the engagement of the catch element by first latch element, and the arrangement is such that pressure applied to the closed door effects the release of the catch element and allows the door to open.

The catch element and the first latch element in such an arrangement preferably have projections which interengage when the door is fully closed, the catch element projection then serving as said stop which serves to hold the latch element in its locking position, inward pressure applied to the closed door causing the projections to disengage.

In such a case a further stop is provided which serves to prevent retraction of the first said latch element as the door is being closed, the interengagement of the latch element and catch elements on release of the door, after closure, serving to pivot the first latch element slightly so that engagement of the second latch element by the catch element when pressure is subsequently applied to the appropriate region of the door permits the first latch element to clear said stop and allows it to be displaced with the second latch element.

However the invention is not restricted to touch release catch mechanisms, and in an alternative arrangement in accordance with the invention there is conveniently provided a separate movable stop which serves to hold the first latch element in the locking position both when the door is closed and on closure, the stop in this case being movable from its operating position to allow the first latch element to retract under the pressure of the spring acting between the two latch elements, and thus permit the door to be opened.

The present invention is concerned more specifically with a touch release actuated door of a washing machine or like equipment operating in conjunction with an interlock system so as to ensure that access to a movable drum or other movable member cannot take place when the equipment is operating, and for operation of the equipment to be prevented if the door is not properly closed.

In such equipment, incorporating a touch release the pivoting movement of the first said latch element on engagement by the catch element when the door is closed serves to actuate an electrical switch which permits the apparatus to be operated, the subsequent return of the latch element to its initial position when released, as pressure is applied to the door to open it, deactuating the switch and de-energising the apparatus.

Alternatively a switch may be actuated by depression of the second latch element by the catch element, to permit the apparatus to be operated, when the door is closed.

Conveniently in both instances, as a further safety measure, the apparatus includes a baulk member movable into the path of the first latch element so as to prevent its displacement from the locking position despite release by the catch element when it is inadvisable to open the door, for example when the drum is rotating, in the case of a washing or spin drying machine.

Two embodiments of the invention will now be described, as applied to a 'front loader' type of washing machine, although it is to be understood that application of the invention is not restricted to this type of machine; it could, for example, equally well be applied to a 'top loader' type of washing machine; to a tumble type clothes dryer; or to a combination 'washer dryer'. Further, the invention, as applied to a washing machine, may be conveniently associated with a door interlock inhibiting arrangement which may have electrical and/or pneumatic control means which in each instance may include a delaying feature used to ensure that the washing machine door can not be opened until, for example, the moving drum has come to rest, or until the amount of liquid left in the machine is such that it is safe to open the door.

In the accompanying schematic drawings, Figure 1 represents a top view of a washing machine 'touch release' door interlock mechanism according to the invention. Figures 2 to 5 show the same mechanism in different states of operation, and Figure 6 shows an alternative mechanism without the touch release feature.

Referring first to the mechanism illustrated in Figures 1 to 5, the mechanism comprises a catch 1, pivotally mounted about a pin 2 within a door 3 of a washing machine, the catch being spring-loaded into a forwardly projecting position by a compression spring 4 positioned between an inside panel 5 of the door and a return arm 1 b of the catch 1. The arrangement is such that the nose 1 a of the catch extends through a slot 5a in the panel, the slot having sufficient extent to allow pivoting of the catch in operation.

With the door in its closed position the catch enters through an opening 10 in the body 12 of an inhibit mechanism 13 secured to the inside of a front wall 14 of the washing machine cabinet. A flexible gasket 9 which extends around the loading port 15 of the washing machine. serves not only to seal the door when closed (see, e.g. Figure 2) against the egress of washing liquid, but also provides back pressure so that when the door is released from its closed position it can spring open. Alternatively, such pressure may be provided by separate means, not shown.A latch plate 16 forming part of the inhibit mechanism 13, in which it is slidably mounted, is located to one side of the opening 10, its full movement away from the opening being inhibited, if appropriate, by a solenoid operated and/or pneumatically operated plunger 11 whose function is determined according to the state of the washing machine programme. Any movement of the latch plate 16 away from the opening which may occur is resisted by an up-standing projection 12a forming part of the body 12 of the inhibit mechanism. However, the latch plate can pivot about a 'knee' 12b, also forming part of the body 12, thereby enabling full movement of the latch plate to be achieved. The degree of pivoting of the latch plate is limited by another part 1 2c of the body 12 (see Fig. 4).

At its outer end, i.e. adjacent the opening 10, the latch plate 16 has a raised projection 16a capable of engagement with a stepped portion 17a of a plunger 17 on the one hand, and with a recess Ic in the nose la of the catch 1.

A second raised projection 16b intermediate the two ends of the latch plate 16 engages with one end of a compression spring 18 whose other end is in engagement with the plunger 17. A second compression spring 19 alongside spring 18 is positioned between the plunger 17 and another part 12d of the body 12. The force exerted by the spring 4 associated with the catch 1 is arranged to be greater than the combined forces exerted by the springs 18 and 19. A micro-switch 21 which controls the operation of the washing machine has its operating plunger 21a in engagement with an adjacent surface of the latch plate 16 so holding the plate in sliding contact against the body 12. In this position the switch is in its 'OFF' state.When the latch plate 16 is tilted to the position shown (see Figure 4) the switch plunger 21a is depressed and the switch is then in its 'ON' state.

Considering now a sequence of operations such as would occur, for example when the washing machine door is shut at the start of a washing programme and at the end of the programme when the door is opened.

Figure 1.

The washing machine door 5 is ajar; the interlock plunger 11 is inoperative; and the switch 21 is 'OFF', hence the machine cannot be operated. Figure 2.

As the door 5 is pushed to, the catch 1 enters the opening 10 and is deflected against the pressure of spring 4 by the latch plate 16 which cannot slide away from the opening, being restrained by the projection 12a. The switch 21 remains 'OFF'.

Figure 3.

Further inward movement of the door causes the catch 1 to move behind the projection 16a of the latch plate 16 and to engage with and move the plunger 17 against the combined pressure of springs 18 and 19.

Figure 4.

Relaxing touch pressure on the door causes it to move outwards against the pressure of the door gasket 9, or some alternative pressurising device. The latch plate 16 is caused to tilt as a result of engagement with the catch 1, thereby actuating the switch, which is moved to its 'ON' state and at the same time removing the sliding restraint on the latch plate, projection 12a. Further inward movement of the latch plate away from the opening is prevented by the recessed portion Ic of the catch 1. In this situation the interlock plunger 11 may move outwards as a result of actuation of the inhibit mechanism by reason of the action of the solenoid or under the influence of pneumatic pressure.If, in fact, the plunger does not move, for example, if the washing machine programme is not initiated then the user can, if required, re-open the door, for example to insert another article.

Figure 5.

If the interlock plunger is not in an interfering position, either as a result of the washing machine having completed its programme, leaving the machine in a safe state for the door to be opened, or, as referred to above, the user wishes to re-open the door, then applying pressure to the door will carry the catch 1 inwards, releasing the latch plate 16 which can then move further away from the opening 10 under the influence of spring 18 acting against projection 16b. The side of the nose of the catch 1 now rests against the plunger 17. The gasket 9, or other pressurising means, then causes the door to open taking with it the catch 1 and allowing the spring 19 to return both the plunger 17 and the latch plate to their original positions, as in Figure 1.

The second embodiment illustrated in Figure 6 is generally similar to that of Figures 1 to 5, except that the interengaging projections of the catch 1 and latch plate 16 are omitted, as well as the projection 12a, and in order to hold the plate in the locking position there is provided a movable stop member R which, in its operative position, engages an opening in the latch plate 16', and serves to retain the latter in its locking position in which it engages beneath the nose of the catch 1'.

In the closed condition the nose of the catch 1' also depresses the plunger 17', as in the first embodiment, so that as the movable stop is actuated to release the latch plate 16' the latter is urged from the locking position by the spring 18' and allows the door to open.

In this embodiment also the microswitch 21' is located so as to be actuated to the 'ON' state by the depression of the plunger 17' when the door is closed, and is released so as to return to the 'OFF' state the plunger 17' reverts to its original position (as in Figure 1), under the biasing action of the spring 19' when the door is opened.

It will be seen that present invention provides a simple form of door interlocking arrangement suitable for a washing machine which arrangement is of 'self contained' form, i.e. it is effective without being mechanically linked by struts or levers to other parts of the washing machine control system.

Furthermore, the system is sufficiently flexible to allow the door to be re-opened at any time provided the machine is in a 'safe' state, i.e. with its accessible moving parts stationary and in the case of a 'front loader' type of washing machine, when the machine does not contain more than a pre-determined amount of water.

Claims

1. A catch mechanism for securing a member against withdrawal from an engaged position relative to another, but capable of actuation to permit such withdrawal, comprising a catch element carried by one said member and a latch assembly carried by the other member, the latch assembly comprising a pair of separately movable elements one of which, in the engaged position of the members, has a locking position in which it engages the catch element in a manner which prevents said withdrawal, and has associated with it a stop which holds said latch element in the locking position, the other latch element, in the engaged position of the members, being displaced by the catch element so as to compress a spring acting between the two latch elements, the mechanism also including means operable to release the first latch element from the stop means so as to allow the element to be urged away from the locking position by said spring and thereby enable the catch element to be withdrawn, and the mechanism including also further spring means operable to return both latch elements to their initial positions so as again to prevent withdrawal of the catch element when the two members are re-engaged.

2. A catch mechanism according to Claim 1 wherein the catch element is pivotally sup ported by the respective member, and is bi ased into a locking position in which it is engageable by the latch elements when the two members are engaged, the element hav ing a cam surface which produces a pivoting movement of the element against said bias to allow the members to be moved into the engaged position, and being returned to the locking position under said bias when the members are fully engaged.

3. A catch mechanism according to Claim 1 or 2 for use with a door wherein the door is urged towards the open position by compression of a spring, resilient gasket or the like when fully closed, the opening being prevented by the engagement of the catch ele ment by first latch element, and the arrangement is such that pressure applied to the closed door effects the release of the catch element and allows the door to open.

4. A catch mechanism according to Claim 3 wherein the catch element and the first latch element have projections which interengage when the door is fully closed, the catch element projection then serving as said stop which serves to hold the latch element in its locking position, inward pressure applied to the closed door causing the projections to disengage.

5. A catch mechanism according to Claim 4 incorporating a further stop which serves to prevent retraction of the first said latch element as the door is being closed, the interengagement of the latch element and catch elements on release of the door, after closure, serving to pivot the first latch element slightly so that engagement of the second latch element by the catch element when pressure is subsequently applied to the appropriate region of the door permits the first latch element to clear said stop and allows it to be displaced with the second latch element.

6. A catch mechanism according to Claim 1 or 2 incorporating a separate movable stop which serves to hold the first latch element in the locking position both when the door is closed and on closure, the stop being movable from its operating position to allow the first latch element to retract under the pressure of the spring action between the two latch elements, and thus permit the door to be opened.

7. A catch mechanism according to any preceding Claim for the door of a cabinet housing equipment incorporating an electrically driven movable member in which the door is associated with an interlock system operative to prevent opening of the door when the member is being driven, and to prevent operation of the equipment unless the door is fully closed.

8. A catch mechanism according to Claim 7 operative to permit pressure applied to the closed door to release the catch element and allow the door to open wherein pivoting movement of the first said latch element on engagement by the catch element when the door is closed serves to actuate an electrical switch which permits the apparatus to be operated, the subsequent return of the latch element to its initial position when released, as pressure is applied to the door to open it, deactuating the switch and deenergising the apparatus.

9. A catch mechanism according to Claim 7 or 8 in combination with a baulk member movable into the path of the first latch element so as to prevent its displacement from the locking position despite release by the catch element when it is inadvisable to open the door.

10. A catch mechanism substantially as shown in and as hereinbefore described with reference to Figures 1 to 5 or to Figure 6 of the accompanying drawings.

11. Electrical equipment having a cabinet provided with a door and incorporating a catch mechanism for the door in accordance with any preceding Claim.

12. A front loader type washing machine having within an outer cabinet, a rotatable drum access to the interior of which is provided by a door in the front of the cabinet, and having a catch mechanism for the door according to any one of Claims 1 to 10.