Actuating Assemblies And Components Therefor Particularly Suitable For Electrical Switches

Abstract

A switch assembly comprises an actuating member and a biasing assembly movable along a common longitudinal axis. Initial movement of the actuating member causes deformation of the biasing assembly thereby to energize the same. A position is reached where the biasing assembly moves towards a less stressed condition, such movement being adapted to actuate the device provided with the actuating assembly.

Description

This invention concerns actuating assemblies and components therefor, such assemblies being particularly suitable for use in conjunction with electrical switches For example, such invention may be applied to a pushbutton body for actuating one or more microswitches.

It will be appreciated that in microswitches, operation is effected by a very short movement of a relatively substantial spring-biased operating member. When manually operating such microswitch it is very often difficult, if such switch is effected manually and directly, to be sure that switching has occurred.

One object of this invention is to provide an actuating assembly, and components therefor, which can be used to actuate easily and with a relatively long actuating movement, an operating member having a short operating movement and which is more substantially biased. A further object of the invention is to provide an assembly which incorporates components which effectively produce a mechanical advantage.

Thus according to one aspect of this invention there is provided an actuating assembly adapted to be operatively associated with a device to be actuated, said assembly comprising an actuating member movable with respect to a biasing assembly which comprises a resilient structure having at least a pair of arms, at least one of said arms being engageable by the actuating member and a part of said resilient structure being adapted to engage the device to be actuated, initial movement of the actuating member against the action of the biasing assembly resulting in the deformation of the resilient structure as a result of relative movement between the arms thereof so as to place the biasing assembly into an energized condition whereafter further movement of such actuating member causes the resilient structure to move towards a condition where it is less deformed with a consequent result that movement of said part of the resilient structure which is adapted to engage the device to be actuated occurs in a device actuating direction.

According to one feature of the invention the resilient structure may comprise a pair of intercoupled arms and such resilient structure may be substantially U-shaped. Whilst said resilient structure may be formed in many alternative ways, for example, by fabricating the same from a springy metal, very desirably such resilient structure may be formed principally or wholly from a plastics material which, when appropriately dimensioned, is resilient.

In one embodiment of the invention both of the free end portions of the arms of the resilient structure may be engaged by the actuating member although in other embodiments only one of said arms may be engaged thereby. In such latter embodiments the free end portion may be coupled to, or may be formed with, said actuating member.

In an embodiment where both are free end portions of the arms of the structure are engaged by the actuating member, the resilient structure may be substantially U-shaped and the base of the U may be arranged to engage the device to be actuated and movement of the actuating member causes the two arms of the structure to move towards one another, or alternatively away from one another, whereafter further movement of the actuating member causes movement of the resilient structure as a whole to actuate the device. In an embodiment where only a first arm is engaged by the actuating member said other or second arm may be arranged to engage the device to be actuated and said resilient structure may also be substantially U-shaped so that movement of such actuating member first causes movement of the first of the arms of the resilient structure in a direction towards the second arm and then further movement of the actuating member results in the second arm moving away from said first arm in a device actuating direction.

According to another aspect of the invention there is provided, for incorporation into an actuating assembly in accordance with this invention, a resilient structure.

In order that the invention may be more readily understood four embodiments of electrical switch pushbutton actuating assemblies will now be described by way of example and with reference to the accompanying drawings in which:

FIG. 1 is a front elevational view (with portions broken away) of a first embodiment of pushbutton assembly coupled to a switch;

FIG. 2 is a partly sectioned side view of the assembly of FIG. 1;

FIG. 3 is a view similar to FIG. 1 but showing the assembly coupled to a bank of three switches;

FIG. 4 is a front elevational view (with portions broken away) of a second embodiment of pushbutton assembly coupled to a switch;

FIG. 5 is a partly sectioned side view of the assembly of FIG. 4;

FIG. 6 is a partly sectioned side view of a third embodiment of pushbutton assembly coupled to a switch; and

FIG. 7 is a further partly sectioned view but shows a fourth embodiment of pushbutton assembly coupled to a switch.

In a first embodiment the actuating assembly comprises a body 1 moulded from a plastics material which basically comprises an inverted L-shaped bracket, the upright 2 of the L serving as a support for an electrical switch mechanism 3 whereas the foot 4 of the L is bored at 5 and is encircled by a cylindrical collar 6 formed on the surface of the foot remote from said upright 2. This collar 6 constitutes a cylinder 7 in which is located a piston part 8 of an actuating member generally designated 9. The actuating member 9 comprises said piston part 8 which carries on its longitudinal axis a stem 10, such stem being screw threaded or serrated at its free end at 11 and receives a pushbutton 12.

An inwardly directed flange 13 on the collar 6 prevents the actuating member 9 from being withdrawn from the collar 6 in one direction, whilst the pushbutton 12 (once it has been attached to the stem) prevents withdrawal of the actuating member 9 in the opposite direction.

The piston part 8 is provided, in its end face remote from the stem 10, with a blind, axially positioned, bore 14 which tapers inwardly towards its inner end so that the bore 14 is generally of frustoconical shape.

In this embodiment the upright 2 of the L-shaped bracket constituting the body 1 is adapted to have secured thereto the switch 3, which is a microswitch and the form and shape of this microswitch 3 is chosen so that its spring-biased operating member, designated 15, lies directly beneath the bore 14 in the bracket and its line of movement lies on the longitudinal axis of the actuating member 9.

Interposed between the actuating member 9 of the assembly and the operating member 15 of the switch is a substantially U-shaped resilient structure 16. The arms 17 of the U are splayed outwardly and carry on their free extremities enlargements 18 which constitute cams which engage the internal surfaces of the frustoconical blind bore 14 in the piston part 8 of the actuating member 9. The base of the U-shaped resilient structure 16 carries a plate 19 which engages the operating member 15 of the switch 3.

In use, when it is desired to operate the switch 3, the pushbutton 12 of the assembly is depressed and as a result in such depression the actuating member 9 moves towards the switch 3 and initially the arms of the resilient structure 16 are merely forced to travel along the walls of the frustoconically shaped blind bore 14 with the result that they are forced towards one another. A stage is reached, however, when the force required to deform the arms 17 of said resilient structure 16 further is greater than the force required to move the spring-biased switch operating member 15 and at this stage further depression of the pushbutton 12 causes the resilient structure 16 to move as a whole in a direction towards the switch-operating member 15 and such member 15 is moved and the switch 3 is operated.

The collar 6 is externally screw threaded at 20 to enable the assembly to be secured to a support plate (not shown). In FIGS. 1 and 2 a single microswitch is indicated. However in FIG. 3 the plate 19 is extended to each side of the resilient structure 16 so that actuation of the pushbutton 12 causes simultaneous actuation of the operating plungers 21, 22 and 23 of three microswitches secured to the upright 2 in a bank. An aperture 24 (shown in FIG. 2) is provided in the upright 2 so as to allow for situations when three or more switches are to be banked.

In a second embodiment shown in FIGS. 4 and 5 (which in general is similar to the first embodiment) in place of the frustoconical bore 14 of FIG. 2, the piston member 8 is provided with a frustoconical end portion 25 and the arms of the resilient structure 16 engage such end portion 25. The resilient structure 16 in this embodiment is not strictly U-shaped but is cuplike being a circular base 26 having a plurality of upstanding radially disposed arms 27 (chamfered at 28). The end portion 25 increases in diameter in a direction extending away from the arms 27 so that when the actuating member is moved in a switch operating direction by depression of the pushbutton 12 the arms of the resilient structure 16 are forced to travel along the walls of the frustoconical end portion 25 and are accordingly forced away from one another. As in the case of the first embodiment a stage is reached where the force required to deform the arms 27 of the resilient structure 16 is greater than the force required to move the switch operating member 15 and thus at this stage further depression of the pushbutton 12 causes the resilient structure 16 to move as a whole towards the switch operating member.

In this embodiment the resilient structure is formed with a spigot 28 which is positioned centrally of the arms 27 of such resilient structure 16 and this spigot 28 is positioned and dimensioned to ride within a cylindrical blind bore 29 in the piston part 8 of the actuating member so as to locate the resilient structure 16 with respect thereto.

It should be understood that the resilient structure 16 has more than two arms but the term "U-shaped resilient structure" in this specification should be understood to include a structure in which three or more arms are provided which effectively define a cup- or U-shaped structure.

With these arrangements it will be understood that by appropriate selection of the strength of the resilient structure 16 in relation to the strength of the switch operating member biasing means, a relatively long but light movement of the pushbutton results in a positive operation of the operating member of the switch which would normally have a short but relatively highly biased travel.

The third embodiment of pushbutton assembly shown in FIG. 6 is, in many ways, similar to the first embodiment already described. This third embodiment has an inverted L-shaped bracket 1 and a collar 6 upstanding therefrom housing an actuating member having a piston part 8, a stem 10 and a pushbutton 12.

In this third embodiment however, the piston part 8 is not provided with a blind frustoconically shaped bore and furthermore the U-shaped resilient structure 16 has its base pivotally supported at 30 on the upright 2 of the L so that the free end portion of one of its arms (designated 31) engages the surface of the actuating member 9 remote from the stem 10, whilst the equivalent portion (designated 32) of the other arm of the resilient structure engages the switch operating member 15. Thus, in this embodiment initial depression of the pushbutton 12 causes the arms 31, 32 of the resilient structure 16 to be moved towards one another and to energize such resilient structure 16 whereafter continued depression of the pushbutton results in the energized resilient structure operating the switch-operating member 15.

A fourth embodiment of pushbutton assembly which is shown in FIG. 7 is extremely similar to the third embodiment described above, but in this fourth embodiment the U-shaped resilient structure 16 is not at any point secured to the upright 2 of the inverted L-shaped bracket 1. In fact in this fourth embodiment, whilst the spring is disposed in the assembly in a fashion similar to the third embodiment of FIG. 6, the end portion 31 of the arm thereof is coupled to said piston part. Expediently, the resilient structure 16 is formed integrally with the piston part 8.

For the sake of clarity all switch terminals have been designated 33.

In all the embodiments described advantageously said resilient structure 16 is moulded from a plastics material although it is conceivable that a resilient structure could be fabricated from metal. However, the use of metal would increase cost because of the need for several piece-parts and expensive forming methods such as the sintering of compacted preforms. A satisfactory plastics material from which the assembly in accordance with this invention could be moulded is an acetal resin such as that manufactured and sold under the Registered Trade Mark DELRIN.

Claims

I claim:

1. An actuating assembly adapted to be operatively associated with a device to be actuated, said assembly comprising: an actuating member and a biasing assembly, said actuating member being movable with respect to the biasing assembly along a common longitudinal axis;

said biasing assembly comprising a resilient structure having at least a pair of arms;

at least one of said arms being engageable by the axial movement of said actuating member to move said resilient structure in the axial direction; and

a part of said resilient structure being adapted on movement thereof to engage the device to be actuated, initial movement of the actuating member against the action of the biasing assembly resulting in the deformation of the resilient structure as a result of relative movement between the arms thereof so as to place the biasing assembly into an energized condition whereafter further movement of said actuating member causes the resilient structure to move towards a condition where it is less deformed with a consequent result that movement of said part of the resilient structure which is adapted to engage the device to be actuated occurs in the longitudinal direction.

2. An actuating assembly according to claim 1, wherein at least two intercoupled arms constitute said resilient structure.

3. An actuating assembly according to claim 2, wherein two arms only are provided and such arms together constitute a substantially U-shaped structure.

4. An actuating assembly according to claim 1, wherein plastics material principally forms said resilient structure.

5. An actuating assembly according to claim 1, wherein the free end portions of at least two of the arms of the resilient structure are engaged by the actuating member.

6. An actuating assembly according to claim 5, wherein said resilient structure is substantially U-shaped and the base of the U is arranged to engage the device to be actuated and movement of the actuating member causes the arms of the U-shaped resilient structure to move with respect to one another, whereafter continued movement of the actuating member causes movement of the resilient structure as a whole.

7. An actuating assembly according to claim 1, wherein one only of the free end portions of the arms of the resilient structure is engaged by the actuating member.

8. An actuating assembly according to claim 7, wherein a first arm is engaged by the actuating member and a second arm is arranged to engage the device to be actuated and movement of said actuating member first causes movement of the first of the arms of the resilient structure in a direction towards the second arm and then further movement of the actuating member results in the second arm moving away from said first arm in a device actuating direction.

9. An actuating assembly according to claim 7, wherein the free-end portion engaged by the actuating member is formed integrally therewith.