EP0837484A2

EP0837484A2 - Switch

Info

Publication number: EP0837484A2
Application number: EP97308216A
Authority: EP
Inventors: Barry Boothman
Original assignee: Tenby Industries Ltd
Current assignee: Tenby Industries Ltd
Priority date: 1996-10-16
Filing date: 1997-10-16
Publication date: 1998-04-22
Also published as: EP0837484A3; GB2318453A; GB9621605D0; GB2318453B

Abstract

A rocker switch operating device for a switch having a contact member (10) supported at a fulcrum point and having an open and a closed position. The rocker switch operating device comprises a rocker member (40) adapted to be supported in a switch body, the rocker member having a contact-engaging member (45) depending therefrom. The contact engaging member has a contact engaging portion for engaging the contact member, the contact engaging portion being supported with respect to the rocker member by at least one resilient hook portion (80:81) whereby the contact-engaging member may pass the fulcrum point to urge the contact member between the open and closed positions.

Description

The present invention relates to an electric switch operating mechanism of the rocker type.

Referring first to Figure 1, a conventional switch operating device of the rocker type comprises a pivotable operating member (1) typically having an operating surface (2) for operation by finger pressure, and having two opposing side surfaces (3) extending downwardly from the operating surface, the side faces having, for example, outwardly extending projections (4) which cooperate in formations of the switch body so that the operating member may pivot. A surface (5) opposite the operating surface has a recess (6 - See Figure 2) which typically forms a seat for a spring (7) and plunger (8), the plunger (7) being urged outwardly from the operating member by the spring (8). In this conventional arrangement, the spring is of metal, and the plunger and operating member are of plastics material.

A moving switch contact (10) has a first end portion (11) which alternatively makes and breaks contact with a counterpart contact member (18). The moving contact member has the form of a strip of, for example, brass, the strip having a generally-planar portion (12) bounded at both ends by respective fold regions (13,14), one of which (13) extends into a contiguous second end portion (15) opposite the contact-making region (11). The other fold region extends to a contiguous ridge portion (16) which is itself contiguous with the contact region. The substantially planar region, together with the second end portion and the ridge region form a generally channel-shaped portion having the planar portion (12) as base and the second end portion (15) and one side of the ridge portion (16) forming the walls thereof. The plunger of the switch operating member is disposed within the channel such that rocking of the switch operating member between two end positions causes the plunger to move between the two fold regions. To this end, the contact member is pivotably supported at a fulcrum point on the underside of the base of the channel portion thereof, the support being provided by a conductive member (30).

Referring now to Figure 2, in a first position of the operating member, the plunger is engaged between the fulcrum and the second fold region (13) of the moving contact, which is thereby pivoted so that the first end portion (11) thereof does not make contact with the counterpart contact (18). Finger pressure at one end (21) of the operating surface urges the operating member to pivot, which pivoting motion requires the plunger to retract against the pressure of the spring and then to extend under the action of spring pressure as the plunger moves along the base (11) of the channel of the moving contact, towards the first fold region (13). As the plunger passes the fulcrum (see Figure 3), the moving contact snaps to a closed position wherein the contact (11) at the first end thereof makes contact with the counterpart contact (18). Subsequent pressure at the opposite end (22) of the operating surface re-opens the contacts by snapping the moving contact back to the position of Figure 2 as the plunger passes the fulcrum again.

The plunger may move from engagement in the first fold region to engagement in the second fold region, but normally it will only move from a position intermediate the fulcrum and the first fold region to a position intermediate the fulcrum and the second fold region, and vice versa.

Such switch arrangements, and other similar arrangements are well known in the art. They are however relatively difficult to manufacture. The need for at least three separate parts of the switch operating member - i.e. the rocker member, the plunger and the spring, is disadvantageous, both because of the number of components and because of the difficulty in assembling them.

It is therefore an object of the present invention to provide a rocker switch operating mechanism which at least partly overcomes the above-mentioned difficulties.

According to the present invention there is provided a rocker switch operating device comprising a rocker member adapted to be supported in a switch body, the rocker member having a contact-engaging member depending therefrom, the material of the contact-engaging member providing resilience whereby the contact-engaging member may urge the contact between an open and closed position.

Preferably the material of the contact-engaging member is plastics material.

Advantageously the rocker member is of plastics material and the contact-engaging member is of the same plastics material.

Alternatively the rocker member may be of a first plastics material and the contact-engaging member of a second, different, plastics material.

Conveniently the rocker member and the contact-engaging member are formed in consecutive moulding steps whereby the rocker member and contact-engaging member form an integral device.

Alternatively the rocker member may be a first component and the contact-engaging member be a second component, wherein one of the components has engagement means whereby it may be secured to the other component.

Embodiments of the invention will now be described with reference to the accompanying drawings in which:-

Figure 1 shows a partial perspective view of a conventional switch.

Figure 2 shows the switch in a first, open, state.

Figure 3 shows the switch in a second, closed, state.

Figure 4 shows a side elevation of a first embodiment of the present invention.

Figure 5 shows a perspective view of the embodiment of Figure 4.

Figure 6 shows a view similar to that of Figure 1, but incorporating the switch operating device of Figures 4 and 5.

Figure 7 shows an alternative embodiment of the invention.

Figure 8 shows yet another embodiment of the present invention.

Figure 9 shows a further embodiment of the rocker device of the present invention in which two contact-engaging members are disposed within the confines of the main body portion.

In the figures, like reference numerals indicate like parts.

Referring first to Figure 4 and 5 the rocker (40) has a main body portion (41) having an operating surface (42), to whose ends pressure - e.g. finger pressure - may be applied to move the rocker between two end positions. In the embodiment shown, the main body is trapezoid in cross-section parallel to the longitudinal axis thereof, and is generally rectangular in cross-section in an orthogonal direction thereto. However it will be understood by one skilled in the art that any desired shape could be used and indeed it is possible to use a hollow main body if so desired.

Depending from the main body opposite to the operating surface, there is a rib portion (43) which extends perpendicular to the longitudinal axis of the body and which has end projections (44) adapted for pivotable engagement - see Figure 5 - with counterpart recesses (46) in the main body (47) of the switch. It will be understood by one skilled in the art that the projections are not essential and could be replaced by recesses or other formations performing the same function.

In this embodiment, the rib portion extends beyond the confines of the main body so as to provide sufficient spacing to operate two switch contacts as described below. The end projections (44) have a generally triangular form, with one apex rounded to provide pivoting. The recesses (46) of the main body (47) of the switch are open on one side to allow for engagement therein by the projections (44) so that the rocker (40) is not retained in the recesses, nor secured to the main body of the switch but rather is urged into engagement with the main body of the switch by spring pressure as more fully described below.

This embodiment therefore provides some assembly difficulties again as will be later more fully described.

The rib portion supports two contact-engaging members (45). In this present embodiment, the two contact-engaging members (45) may be integrally moulded with the rocker main body, or may be separate components which are secured to the rib portion thereof. Each contact-engaging member is generally symmetrical and has a downwardly depending V-shaped portion (50) extending into two contiguous hook portions (80,81) which are mutually inwardly directed. In the case of an integrally moulded device, each of the hook portions extends into the rib portion (43) of the rocker, whereas in the case of a two-part device, the hook portions engage with the rib portion.

The material of the contact-engaging member together with its configuration enable the rocker and contact-engaging members to perform similarly to the conventional body-spring-plunger assembly. Specifically, an apex portion (53) of the V of the contact-engaging member is enabled to be moved against a resilience of the hooked portions towards the rib portion of the rocker, during the course of which the hooked portions behave similarly to leaf springs so enabling the apex portion to pass along the base portion of the moving contact and past the fulcrum position. Once the apex of the V has passed this position, the resilience and configuration of the contact-engaging member urges it outwardly towards the undeformed condition thus causing the moving contact to snap to the open or respectively closed position.

The resilience of the contact-engaging member not only serves to move the moving contact between its open and closed positions but also serves to urge the rocker itself into engagement with the main body (47) of the switch (47) in the recesses (46) thereof. In practice, the resilience of the contact-engaging portions also serves to retain the moving contact member within the body of the switch. Thus, during assembly the rocker (40) is first inserted into the switch body (47) with the projections (44) of the rocker engaged in the recesses (46) and then the contact-supporting portion of the switch body is offered to the main switch body (47). It will be seen that care is required during this assembly operation because the rocker will tend to fall out from the recesses (46) when the switch body is tilted, and the contacts (being otherwise free to move until held in position by the contact-engaging members (45)) will also tend to be dislodged if the contact-supporting portion of the body is tilted.

Figure 6 shows the embodiment of Figures 4 and 5 in use with the V portion engaged with the moving contact member (10) near to the second fold region (14) thereof whereby the moving contact is held in the open position.

It will be understood that the V form of this embodiment is not essential to the invention. For example the contact-engaging member may have the form of a solid pillar supported by resilient hook portions, or other forms as desired.

Referring again to Figures 4 and 5, intermediate the contact-engaging members of the rocker, the rib portion has generally rounded portions (56) extending in the same direction as the contact-engaging members.

The previously described v-shaped portions (50) also provide a positive mechanical break, now described:-

Referring to Figure 6, it will be seen that when the rocker (40) is moved from the closed-contact position to the open-contact position the rocker is disposed such that the v-shaped portion (50) of the contact-engaging member (44) is in close proximity to the ridge portion (16) of the contact. If the contacts remain undesirably closed, for example due to contact-welding caused by arcing, in which case the movement of the contact-engaging portion past the fulcrum may not cause sufficient leverage to open the contacts, then the continued contact-opening pressure on the rocker (40) further urges a side of the v-shaped portion (50) intermediate the apex portion (53) and the hook portion (81) to engage with the ridge portion (16) of the contact to mechanically move the contact from the closed to the open position.

Figures 7 and 8 shows alternative embodiments in which the contact-engaging member is asymmetrical. In Figure 7, the contact-engaging member (65) has a first half which is similar to one half of the contact-engaging member shown in Figure 4, but the other side is truncated at the remote extremity of the V-portion so that the end (66) of the V-portion (68) is supported on the bearing portion (67) of the rib portion (44) but only connected to the rib portion via the remainder of the V-portion (68) and the single hook portion (69).

Turning to Figure 8 the contact-engaging portion (181) shown is integrally moulded with the body portion and consists of a first part (182) contiguous with the body portion which extends generally parallel to the longitudinal axis thereto and is connected to the body portion via a resilient fold portion (183) at one end thereof, the other end thereof providing a second resilient-fold portion (184) which extends into a downwardly-depending finger portion (185) adapted to engage with the base portion of the trough of the moving contact member. The third embodiment is particularly advantageous where the entire rocker device is moulded in a single step, for example using polycarbonate materials.

Turning now to Figure 9, a fourth embodiment of the rocker switch operating member of the invention has, instead of the triangular-like projections (44) of the other embodiments instead circular projections (101), which snap fit into corresponding circular recesses in the main switch body. This rocker, which is of an increased width by comparison with those already disclosed, has two contact-engaging portions within the confines of the main body of the rocker each for operating a contact corresponding to a respective one of two poles of a two-pole switch. The fourth embodiment may be made of nylon, especially filled nylon, and is especially suitable for relatively high current switching.

A number of different techniques may be used to manufacture rocker operating mechanisms in accordance with the invention. Specifically, a single moulding operation may be used, having the results that the main body of the rocker and the contact-engaging portions are of the same material - for example filled nylon. Alternatively a two-shot moulding technique may be used in which the contact-engaging portion(s) is/are moulded first and then overmoulded with the main body portion of the rocker, or vice versa depending upon the relative melting temperatures of the plastics used for the two components. (The highest melt temperature component would be moulded first.) Thirdly, it is envisaged that the main body of the rocker be moulded in one operation, and the contact-operating member or members be moulded as a separate moulding operation with the two components secured together for example by press fitting or by snapping into a slot.

Where the two-shot moulding technique is used, contrasting colours may be used for the two moulding materials. In such a case, the material of the contact-engaging portion may be carried through to be visible in a portion of the main body, for example an end region thereof, so as to provide an on, or respectively off indication. This may be most effective when the material of the contact-engaging portions is red, in which case a red indicator portion is arranged to become visible when the rocker is on the on condition. However, where the rocker is used in other than mains-switching situations, for example used in automotive situations, different colour end "windows" may be provided to distinguish between different loads, the colour of the material of the window being repeated in the contact-engaging portion.

Examples of materials have been indicated but these are not intended to be restrictive. Many other materials could be used instead, notably acetal copolymer, which is stable and not susceptible to water absorption.

Thus there has been disclosed four embodiments of an advantageous rocker switch operating member, the operating member being of reduced component count in comparison to the rocker operating members of the prior art, the resilience of the rocker device being provided by the material and configuration of the device itself rather than requiring the use of external metal springs.

Claims

A rocker switch operating device for a switch having a contact member supported at a fulcrum point and having an open and a closed position, comprising a rocker member adapted to be supported in a switch body, the rocker member having a contact-engaging member depending therefrom, the contact engaging member having a contact engaging portion for engaging said contact member, said contact engaging portion being supported with respect to the rocker member by at least one resilient hook portion whereby the contact-engaging member may pass said fulcrum point to urge the contact member between said open and closed positions.
A rocker switch operating device as claimed in claim 1 wherein the material of the contact-engaging member is plastics material.
A rocker switch operating device as claimed in claim 2 wherein the rocker member is of plastics material and the contact-engaging member is of the same plastics material.
A rocker switch operating device as claimed in claim 2 wherein the rocker member is of a first plastics material and the contact-engaging member is of a second, different, plastics material.
A rocker switch operating device as claimed in claim 2 wherein the rocker member and the contact-engaging member are formed in consecutive moulding steps whereby the rocker member and contact-engaging member form an integral device.
A rocker switch operating device as claimed in claim 1 or claim 2 wherein the rocker member is a first component and the contact-engaging member is a second component, and wherein one of the components has engagement means whereby it may be secured to the other component.
A rocker switch operating device as claimed in any preceding claim further comprising means for mechanically moving the contact member from the closed position to the open position.
The rocker switch operating device as claimed in claim 7, wherein said means for moving the contact member comprises a further portion of the contact-engaging member which engages with a ridge portion (16) of the contact member and transmits a mechanical opening force thereon.
The rocker switch operating device as claimed in claim 8, wherein said further portion of the contact-engaging member is disposed between said resilient hook portion and the apex of the contact-engaging member.