GB2031053A

GB2031053A - Improvements in or Relating to Interlock Mechanism

Info

Publication number: GB2031053A
Application number: GB7838649A
Authority: GB
Original assignee: TI Domestic Appliances Ltd
Current assignee: TI Domestic Appliances Ltd
Priority date: 1978-09-29
Filing date: 1978-09-29
Publication date: 1980-04-16
Also published as: DE2938659A1; FR2438727A1; GB2031053B

Abstract

An interlock mechanism for holding closed the access door of a dish washer, tumbler dryer, spin dryer for example comprises a door latch 1 on which a switch actuator 6 is slidably mounted. The actuator is in the form of a metal strip with an angled portion 7 at one end and an upturned lip 8 at the other. Also mounted upon the latter is a microswitch 5 operable by the portion 7 when the actuator 6 is moved relatively to the latch. The mechanism may be associated with a timer and a thermally responsive device 31 in a manner such that the door cannot be opened except under specified conditions. <IMAGE>

Description

SPECIFICATION improvements in or Relating to Interlock Mechanisms This invention relates to interlock mechanisms and has particular although not exclusive reference to interlock mechanisms for washing machines especially those for home use.

However, the invention may also be embodied in dish washers, tumbler dryers and spin dryers.

It is a requirement of many domestic machines of the type just mentioned that a user be prevented from opening the door of the machine giving access to the interior of the machine until the latter has reached a point in an operating cycle at which opening the door does not expose the user to hazards. For example, it must not be possible to open the door of a washing machine when the latter contains very hot water or when the machine drum is spinning at high speed, for example, during a moisture extraction cycle.

Furthermore, it must not be possible for a user to set the machine in operation with the door open.

According to the present invention, an interlock mechanism comprises a latch member movable in a guideway, an actuator mounted on the latch member for movement relatively thereto, and a switch mechanism operable by the actuator.

The switch mechanism may also be mounted upon the latch member.

In one embodiment of the invention, the actuator is slidably mounted in a channel formed in or provided on the latch member.

in one embodiment of the invention, the actuator is provided with a surface for operating the switch mechanism, and may also have another surface for operation by another member.

The latch member may form the latch of a door and may be formed at one end with a bevelled surface for co-operation with a catch to hold the door in its closed position. In this case, the actuator may be operated by the catch on the door in which case the actuator has the other surface referred to above and which may comprise the surface of a lip on the actuator.

The latch member may be coupled to an operating member operation of which is required to move the latch member out of engagement with the catch when the door is to be opened.

The operating member may be operatively associated with safety devices for preventing operation of the member in specified circumstances.

By way of example only, an embodiment of the invention suitable for use on a domestic washing machine will now be described in greater detail with reference to the accompanying drawings of which: Figure 1 is a plan view of part of the interlock mechanism, Figure 2 is a section on the line Il-Il of Figure 1 with other components shown, Figure 3 is a diagrammatic representation of part of a safety interlock mechanism for a washing machine, and Figure 4 corresponds with Figure 3 but shows moving parts in different positions.

Referring first to Figures 1 and 2, the interlock mechanism shown forms part of a door catch for the door of an automatic washing machine.

The mechanism comprises a door latch 1 mounted for limited, longitudinal sliding movement in a guideway (not shown). An end portion of the latch 1 is extended as at 2 and the extension is bevelled as at 3 to co-operate with fixed catch member to be described later.

One face of the latch 1~that shown uppermost in Figure 1~has a longitudinal channel 4 which extends over the major part of the latch from the extremity of the extension 2 to the face of a microswitch indicated diagrammatically by block 5 and mounted upon the latch 1 at that end thereof remote from the extension 2.

Mounted for sliding movement in the channel 4 is a switch actuator 6 consisting of a metal strip angled at one end as at 7 and upturned at the other end to form a small lip 8. The actuator 6 is held in the channel 4 by a bridging piece 9 on which is mounted a coupler 10.

The actuator 6 is freely movable in the channel 4, its limits of movement being defined by the bridging piece 9 and the inward position of the operating button 1 1 of the microswitch 5.

The latch mechanism is, in Figure 2, shown mounted behind the front panel 12 of a washing machine, the latch 1 protruding through an opening 13 formed in the side wall of a loading opening indicated at 14. The guideway in which the latch 1 is slidably mounted is not shown in Figure 2.

Associated with the opening 14 is a closure door part of which is shown in Figure 2 at 1 5. The door carries the fixed catch referred to above and reference 16 in Figure 2. The fixed catch has an inclined lead-in edge 17 and an undercut recess 18.

In operation, the contacts of the microswitch 5 are in series connection with the electricity supply to the machine. When the contacts of the microswitch are open, the machine is isolated from the supply and is connected thereto only when those contacts are closed. With the moving parts in the positions shown in Figures 1 and 2, the contacts are opened.

On closure of the door 15, the inclined edge 17 of the catch 16 strikes the bevelled edge 3 of the latch 1 and pushes the latter to the right as viewed in Figures 1 and 2 against the action of resilient restoring means (not shown). The latch 1 slides in its guideway and in due course, the extremity of the bevelled surface 3 clears the extremity of the edge 1 7 and the latch is moved to the left into the recess 18. This movement takes place under the action of the restoring means. However, as the extremity of the edge 1 7 clears the extremity of the surface 3, the former extremity contacts the lip 8 of the switch actuator 6 and prevents the latter moving to the left with the latch 1.The movement of the latch 1 relative to the switch actuator 6 brings the angled end 7 of the latter into contact with the operating button 11 of the microswitch 5 so operating the latter and closing the contacts of the microswitch 5 and connecting the machine to the electricity supply.

On engagement of the latch 1 in the recess 18, the door 15 is held closed.

If a user now wishes to open the door 15, the latch 1 is withdrawn by a suitable mechanism not shown in Figures 1 and 2 until the extremity of the edges 3 and 17 are clear of one another. This movement of the latch 1 occurs relatively to the switch actuator 6 and the angled end 7 of the latter ceases to bear on button 11 and the contacts of the microswitch 5 open so isolating the machine from the electricity supply.

It will be appreciated that the switch actuator 6 is effectively concealed and mis-operation of the latch to operate the microswitch and close the contacts thereof with the door open is difficult.

Moreover, if the door is not fully closed and latched, the microswitch will not be operated and its contacts closed. The relative simplicity of the latch 1 will also be evident.

In many cases, the interlock just described will be associated with other safety controls and Figures 3 and 4 illustrate the incorporation of other controls normally provided on a domestic washing machine.

The interlocks are incorporated in a washing machine having a timer which cycles the machine through its programs one or other of which is selected by the user. The timer has a drive shaft 19 to which is secured a cam 20 whose periphery is slotted as at 21. Co-operating with the slot 21 is a projection 22 carried by a slide 23 movable under the action of a door opening push button 24 via an inclined surface 25 of the latter and a second projection 26 on the slide 23. The movement of the slide 23 that occurs when the push button is depressed takes place against the action of a spring 27 secured to a lever 28 pivotally mounted as at 29 and secured at one end to the slide 23 by a pivotal connection 30 and loosely mounted, at the other end, on the coupler 10 of the latch 1.

Also associated with the push-button 24 is a thermal delay mechanism indicated in Figure 3 by block 31. The thermal delay mechanism 31 is of known construction and is responsive to operation of the machine. The delay mechanism may incorporate a bimetal member in thermal contact with an electric resistance heater that is energised when the machine is in operation. The bimetal member operates a stop 32 which can be extended by the bimetal member into the path of movement of the push button and so prevent inward movement of the latter whilst the machine is in operation.

Figure 3 shows the interlock system with the moving components in the positions they occupy when the machine is out-of-operation with the timer de-energised and the door 15 5 open. The stop 32 of the thermal delay mechanism is withdrawn out of the path of movement of the push button 24, the timer cam slot 21 is aligned but not engaged with the projection 22, and the contacts of the microswitch 5 are open because the angled end 7 is clear of the operating button 11 of the switch.

To bring the machine into use, the user loads it with articles to be washed, shuts the door 15, and selects a required program. Closure of the door causes the contacts of the microswitch to close thereby connecting the machine to the electricity supply following which the timer and the thermal delay mechanism are energised.

Figure 4 shows the moving parts in the position they occupy after the machine has started. The timer cam 20 has commenced to rotate and the slot 21 has moved out of alignment with the projection 22. The stop 32 of the thermal delay mechanism has been extended into the path of movement of the push button 24.

If now a user attempts to open the door by operating push button 24, it is found that depression of the latter is prevented by the stop 32. Even if the thermal delay mechanism 31 is inoperative, depression of the button cannot occur because movement to the left as viewed in Figure 4 that is required to permit depression is prevented by the stop 22 contacting the periphery of the cam 20.

At the end of the selected program, the timer cam stops in the position shown in Figure 3 with the slot 21 aligned with the projection 22. After an appropriate time delay, the mechanism 31 operates to withdraw the stop 32 from the path of movement of the push button and the user may then depress the latter.

Depression of the push button 24 moves the slide 23 to the left because of the interaction between the surface 25 and the stop 32.

Projection 22 enters the slot 21 and the lever 28 pivots so withdrawing the latch 1 from engagement with the fixed catch 16 and the door can now be opened. As the latch is withdrawn from engagement with the fixed catch 16, operating button 11 of the microswitch moves away from the angled end 7 of the actuator 6 and the contacts of the microswitch open thereby disconnecting the machine from the electricity supply.

The interlock mechanism shown in Figure 1 and 2 can, of course, be used with other safety interlocks than those shown in Figures 3 and 4 and indeed, as has been made clear above can be used by itself in appropriate circumstances.

Claims

1. An interlock mechanism comprising a latch member, an actuator mounted upon the latch member for movement relatively thereto, and a switch mechanism operable by the actuator.

2. A mechanism as claimed in claim 1 in which the switch mechanism is mounted upon the latch member.

3. A mechanism as claimed in claim 1 or 2 in which the latch member is formed or provided with a channel, the actuator being slidably mounted in the channel.

4. A mechanism as claimed in any one of the preceding claims in which the actuator has a portion for operating the switch mechanism.

5. A mechanism as claimed in claim 4 in which the actuator has another portion by means of which the actuator is movable relatively to the latch member.

6. A latch mechanism for a door comprising a latch member for holding the door in a closed position, an actuator mounted upon the latch member for movement relatively thereto during opening and closing movement of the door, and a switch mechanism operable by the actuator.

7. A latch mechanism as claimed in claim 6 and further comprising a co-operating member adapted to cooperate with the latch member to hold the door in its closed position, and in which, during the final movement of the door into its closed position, the co-operating member engages the actuator and permits movements of the latter relative to the latch member to operate the switch mechanism.

8. A latch mechanism as claimed in claim 7 in which the latch member is mounted for movement relatively to the co-operating member and in which the final movement of the door into its closed position causes the latch member to move into door locking engagement with the cooperating member, the co-operating member holding the actuator against movement relative to the co-operating member, the movement of the latch member relative to the actuator producing operation of the switch mechanism.

9. A latch mechanism as claimed in claim 6, 7 or 8 in which the mechanism is of the construction claimed in any one of claims 2 to 5.

10. A latch mechanism as claimed in any one of claims 6 to 9 in which means are provided for releasably holding the latch member in a first, door-holding position.

11. A latch mechanism as claimed in claim 10 and further comprising means for disengaging the latch member to permit the door to be opened and in which the releasable holding means operate to prevent actuation of the disengaging means.

12. An interlock mechanism substantially as herein described with reference to and as illustrated by Figures 1 and 2 of the accompanying drawings.

13. A latch mechanism for a door substantially as herein described with reference to and as illustrated by Figures 3, 3A, 4 and 4A of the accompanying drawings.

14. A washing machine having a door latch mechanism as claimed in any one of claims 6 to 11 and 13.