EP0381416A2

EP0381416A2 - A latching mechanism

Info

Publication number: EP0381416A2
Application number: EP90300905A
Authority: EP
Inventors: James Philip Graves
Original assignee: Caradon Plastics Ltd
Current assignee: Caradon Plastics Ltd
Priority date: 1989-02-01
Filing date: 1990-01-29
Publication date: 1990-08-08
Also published as: CA2008791A1; GB8902205D0; EP0381416A3

Abstract

A latch mechanism for a cashbox having a base and lid is made substantially of acetal. It comprises a moulded acetal latch member(8) pivotally mounted for movement between an operative latched position in which the cashbox lid is locked to the cashbox base. The latch member (8) is acted upon by a low voltage solenoid which coacts with a rocker (6). The rocker holds the latch member (8) in the operative latched position, but when released by the solenoid releases the latch so that it can pivot to the inoperative unlatched position under the action of an integral sprung extension (11) and/or the action of a separate spring in which position the box can be opened.

Description

The present invention relates to a latching mechanism. The mechanism is intended particularly, but not exclusively for a cash box.
Known latching mechanisms of this type are usually made of metal, have many parts and are therefore difficult and expensive to produce and maintain and are noisy in operation.
According to the present invention, there is provided a mechanism comprising actuator means and a latch, in which the latch is disposed to contact a catch to perform a latched action, characterised in that the actuator means is disposed for movement between a first position in which the latch is held in an operative latched position and a second position in which the latch is released to enable it to release the catch under the action of its own inherent resilience.
In a preferred embodiment of the invention, the latch is pivotally mounted and is moulded from resilient synthetic plastics material such as acetal. The actuator means comprises a low voltage solenoid which coacts with a rocker member. The rocker member is pivotally mounted for movement between the first and second positions. The rocker member coacts with the latch and the surfaces of contact are formed to facilitate this. The latch comprises a resilient extension which coacts with a projection formed on the housing for the latch. This resilient extension effectively acts to store energy which may be released to pivot the latch to an unlatched position.
In order that the invention may be more clearly understood, one embodiment thereof will now be described, by way of example, with reference to the accompanying drawings, in which:-

Figure 1 shows a section through a latching mechanism according to the invention with the mechanism in the locked position,
Figure 2 shows a section through the mechanism of Figure 1 but with the mechanism in the unlocked position, and
Figure 3 shows a cross-section through a cash box incorporating a modified form of the mechanism shown in Figures 1 and 2.

Referring to Figure 1, the mechanism comprises a low voltage solenoid 1 incorporating a movable actuator rod 2. A head 3 is fixed to the free end of the rod 2 and a compression spring 4 is constrained to act between that head 3 and the housing 5 of the solenoid. The head end of the solenoid coacts within an intermediate rocker 6. The rocker 6 is mounted for pivotal movement about a pivot 7 disposed on the support structure for the mechanism. Where the latching mechanism is a cash box, this support structure may be the box itself or connected to the box.
A latch member 8 operatively coacts with the rocker. This latch memeber 8 is also pivotally mounted about a pivot 9 which may also be supported as the pivot 7. Both the latch member 8 and the intermediate rocker 6 are moulded, for example, injection moulded, from a synthetic plastics material, such as acetal. The member 8 comprises jaws 10 at one end and a resilient energy storing extension 11 at the other. The jaws are operative to engage in the apertures 12 of an extrusion 13 which is part of or attached to for example, the lid (not shown) of the cash box mentioned earlier. The extension 11 coacts with an elongate flexible synthetic plastics material (again such as acetal) dependant projection 14 to impose a load on that extrension 11 against the natural residence of the material in the locked position of the mechanism shown in Figure 1.
To unlock the mechanism, power is applied to the solenoid. This withdraws the moveable actuator rod 2 into the housing 5 of the solenoid against the action of the compression spring 4 thus compressing the spring (not shown on Figure 2). The withdrawal of the actutor rod 2 pivots the intermediate rocker 6 anticlockwise about its pivot 7. This in turn releases the latch member 8 which pivots clockwise about its pivot thus releasing the energy stored in the resilient exension 11. A stop 15 abutts the surface of the latch member 8 to limit this clockwise movement. The relative disposition of the extension 11 and the dependant projection 14 are such that their tips slide past one another. The clockwise movement of the latch member 8 withdraws the jaws 10 from the aperture 12 thus releasing the extension 13 and with it the lid of the cash box (which itself may be spring loaded).
When power is removed from the solenoid 1, the compression spring 4 acts to return the rod 2 to its original position in turn returning the intermediate rocker 6 to its original position (as shown in figure 1) where it can again be contacted by the latch member 8. This contact is actually renewed on closing the lid of the cash box (not shown). This closure action results in the lower end of the extension 13 contacting the lower jaws of the jaws 10, pivoting the latch member 8 in an anticlockwise direction and reengaging the upper jaws of the jaws 10 in the aperture 12 to lock the mechanism. This anticlockwise movement of the latch member 8 also causes the tips of the projection 14 and extension 11 to slide past one another in the reverse dirction to hitherto, further movement compressing the extension 11 and storing energy in it for the next unlatching operation. In addition the end of the latch member 8 remote from the jaws 10 reengage in the intermediate rocker 6. The parts of the mechanism are then in the position shown in Figure 1 once again.
The shape of the external periphery of various parts of the mechanism are carefully chosen to assist operation. These include the lower surface 20 of the extension 13 and upper surface 21 of the lower jaw 10, the tips 22 and 23 of the projection 14 and extension 11 respectively and the end 24 of the latch 8 and lower part 25 of the rocker 6. These shapes are curved to facilitate movement over one another.
Apart from simplification compared with conventional latching mechanisms, maintenance requirements such as lubrication are also reduced.
Referring to Figure 3, a modified form of the mechanism described with reference to Figures 1 and 2 is shown incorporated in a cashbox 30. The cashbox comprises a base 31 and a lid 32. In this modified form, the latch mechanism is the same except that the energy storing extension 11 is shorter and does not abutt the dependent projection 14 and a conventional tension spring 33 is connected between the member 8 and a fixed point operative to urge the member 8 in a clockwise direction to replace the force provided by projection 14 in the previous embodiment. Equivalent parts bear the same reference numerals in both embodiments. In addition, a hood 34 is provided to cover the jaws 10 of the latch member 8 to avoid inadvertent depression of the latch.
It will be appreciated that the above embodiment has been described by way of example only and that many variations are possible without departing from the invention. For example, although acetal has been described as the preferred material, other materials having the required inherent resilience could equally well be used. Furthermore, there are many other purposes for which the latching mechanism may be used other than for a cash box. The solenoid could be replaced by a wholly mechanical actuator or such an actuator could be provided in addition to the solenoid.

Claims

1. A mechanism comprising actuator means and a latch, in which the latch is disposed to contact a catch to perform a latched action, characterised in that the actuator means is disposed for movement between a first position in which the latch is held in an operative latched position and a second position in which the latch is released to enable it to release the catch under the action of its own inherent resilience.

2. A mechanism as claimed in claim 1, in which the latch is pivotally mounted for movement in and out of a latched position.

3. A mechanism as claimed in claim 1 or 2, in which the latch is moulded from resilient synthetic plastics material.

4. A mechanism as claimed in claim 1, 2 or 3, in which the actuator means comprises a low voltage solenoid and a rocker member disposed to coact with the solenoid.

5. A mechanism as claimed in claim 4, in which a rocker member is mounted for pivotal movement between the first and second positions.

6. A mechanism as claimed in claim 5, in which the rocker member is operative to coact with the latch and the surfaces of contact are formed to facilitate this .

7. A mechanism as claimed in any preceding claim, in which the latch comprises a resilient extension which acts to store energy when the latch is in the latched position and to release it to release the latch.

8. A mechanism as claimed in any preceding claim, in which a spring is connected between the latch to urge the latch from the latched to the unlatched position.

9. A mechanism as claimed in any preceding claim, in which the latch is moulded from acetal.