GB2337856A

GB2337856A - Rocker switch

Info

Publication number: GB2337856A
Application number: GB9802020A
Authority: GB
Inventors: Robert Phelps
Original assignee: PRITCHARD PATENT PRODUCT COMPA
Current assignee: PRITCHARD PATENT PRODUCT COMPA
Priority date: 1998-01-30
Filing date: 1998-01-30
Publication date: 1999-12-01
Anticipated expiration: 2018-01-30
Also published as: GB2337856A8; GB2337856B; GB9802020D0

Abstract

A rocker switch includes first 2,5 and second 3,6 sets of contacts. A manually operable lever 8 is mounted for both pivotal (about pivot pin 9) and translational (in slot 8e) movement between the contact sets 2,5 or 3,6. An over-centre mechanism 10 is operable to resiliently urge the rocker lever 8, selectively, into either a first or second pivotally and translationally displaced position. During pivotal displacement, the rocker lever 8 is translationally urged by the over-centre mechanism 10 in a direction to cause on or other of the contact sets 2,5 or 3,6 to close (fig 3) and thereafter is translationally displaced in a reverse direction (slot 8e, fig 5) to allow that contact set to return to its initial state.

Description

2337856 1 IMPROVEMENTS IN OR RELATING TO ELECTRICAL SWITCHES The present

invention relates to electrical switches, and particularly but not exclusively to a switch which is suitable for controlling the energisation of a double-acting solenoid or the like.

Such solenoids may, for example, be used to actuate, i.e. change over, the movable blades of points incorporated in model railway track layouts. Such a solenoid usually includes an armature which is coupled to the movable point blades, the armature, and therefore the point blades, being displaceable from a first to a second position when a first winding of the solenoid is energised, and being displaceable in the reverse direction from the second to the first position, when a second winding is energised. Such a point solenoid only requires to be energised momentarily, sufficient to displace the armature and change over, or initiate change over of, the point blades, the solenoid thereafter being de-energised until change over of the point is required again. For this purpose, the solenoid is energised via a switch having normally open contacts which, upon activation of the switch, temporarily close and then re-open.

It is an object of the present invention to provide an improved electrical switch of the aforementioned type.

According to the present invention, there is provided a rocker switch comprising: first and second sets of contacts, each contact set being switchable between first and second states; a rocker arrangement mounted for both pivotal and translational movement between the contacts sets; and an over-centre mechanism operable to resiliently urge the rocker arrangement, selectively, into a first pivotally and translationally displaced position or a second pivotally and translationally displaced position; the rocker arrangement, during pivotal displacement between the first and second positions, being translationally urged by the over-centre mechanism in a direction to cause one or other of the contact sets to change from its first to its second switched state, and thereafter being translationally displaced in a reverse direction to 2 allow that contact set to return to its first switched state.

Each contact set, when changed from its first to its second switched state, for example from a normally open-circuit state to a closed-circuit state, may act on the rocker arrangement to initiate translational displacement thereof in the reverse direction, thereby to change the contact set back to its initial open-circuit state.

In one embodiment, the rocker arrangement comprises a rocker member in the form of a generally inverted T-shaped operating lever. The generally upright limb of the inverted T comprises an operating arm by which the lever may be manually rocked. The transverse limb forming the base of the inverted T comprises opposed arms each extending generally towards, and being selectively cammingly cooperable with, a respective one of the contact sets. The lever is mounted for rocking movement about a fixed axis defined by a pivot pin or the like which is located in a central slot in the lever base. The slot is elongated in the direction of the opposed, transverse arms, so that the lever may rock about the pin, and also slide along the pin with the limits of the slot, generally transversely towards one or other of the contact sets, when the switch is operated.

The over-centre mechanism includes a compression spring, the upper end of which cooperates with an arm or boss dependent from the centre of the base of the lever, and the lower end of which is fixed at a location coincident with a median plane passing through the pivot pin. The over- centre mechanism acts to resiliently rockingly urge the lever about the pivot pin into one or other of its limit positions on opposite sides of the median plane. However, due to the provision of the transverse slot in the lever, the over-centre mechanism also acts on the lever to displace it bodily, i.e. translationally, generally transversely until the pivot pin selectively engages one or other end of the slot, depending upon whether the lever is in one or the other of its limit positions. As the lever is rocked from one towards the other limit position, initially against the force exerted by the over-centre mechanism, the lever engages and closes the 3 contact set to which it is closer, by virtue of the transverse displacement. This engagement cams the lever in the opposite transverse direction, opening the previously closed contact set, and actuating, or assisting in actuating, the over centre mechanism to cause it to urge the lever towards its other limit position.

In order that the invention may be more readily understood, one embodiment thereof will now be described with reference to the accompanying drawings, in which:

Fig. 1 is an exploded perspective view of the switch; Fig. 2 is a front view of the switch, with the front cover of the switch housing omitted, and showing the operating lever in a first of its two switched positions; Figs. 3 and 4 are front views, showing the operating lever in two respective positions during displacement from its first towards its second switched position; and Fig. 5 is a front view showing the operating lever in its second switched position.

Referring to the drawings, the switch includes a casing comprising a main, hollow, rear casing part 1 containing the switch components, and a front cover (not shown). The switch components includes first and second stationary contact arms 2 and 3 anchored to the base 1 a of the rear casing part 1 adjacent opposite sides thereof. Each stationary contact arm is associated with a movable, spring contact arm 5, 6 joined by a common base part 7 anchored to the base 1 a of the rear casing part 1. The contact arms, 2, 3 and 5, 6, adjacent their free upper ends, are provided with respective make-and-break contacts 2a, 3a, 5a, 6a, and the spring contact arms 5 and 6 are bent or otherwise formed to provide inclined cam surfaces 5b, 6b respectively. The pairs of contacts arms 2, 5 and 3, 6, and their associated contacts, form first and second normally open-circuit contact sets, i.e. the contacts 2a, 5a, and 3a, 6@ are normally spaced apart as shown in Figs. 2 and 5.

The stationary contact arms 2, 3, and the common base 7 of the 4 movable contact arms 5, 6, are provided with connector portions 2b, 3b and 7b respectively, protecting below the base 1 a of the casing part 1 for connection to, for example plugging into, the control circuit of a doubleacting solenoid or the like as will be described later.

Mounted in the casing part 1 between the upper free ends of the two contact sets is an operating lever or rocker member 8 of generally inverted T shaped configuration. The rocker member includes a generally upright lever arm 8a which projects from the top of the casing part through a slot 1 b therein, and is manually rockable to actuate the switch. The rocker member also includes oppositely directed generally transverse lever arms 8b, 8c provided at their outer ends with curved cam surfaces 8d which are cooperable with the cam surfaces 5b, 6b of the spring contact arms as will be described later. The rocker member is rockably mounted on an axle or pivot pin 9 located in apertures 1 c in the casing part 1 and front cover (not shown), which passes through a slot 8e located at the juncture of the arms 8a, 8b, 8c, and having its longer axis extending in the direction of the transverse arms 8b, 8c.

The rocker member is provided with a trigger or over-centre mechanism which includes a boss 8f depending from the centre of the rocker member.

The boss is engaged in a socket 1 Oa mounted at the upper end of a guide rod 1 Ob slidably and rockably mounted in an aperture 7c in the base 7 of the movable contacts. A compression spring 1 Oc is located and compressed between the base 7 and socket 1 Oa, which urges the socket upwardly against the boss 8f. The axes of the pivot pin 9 and aperture 7c are located in a common upright median plane so that the spring 10c, acting on the boss 8f of the rocker member 8 via the socket 1 Oa, normally resiliently urges the boss 8f to one or other side of the median plane as shown in Figs. 2 and 4, rocking the rocker member to one or other of its inclined, limit positions in which the manual lever arm 8a engages stops 1 d at opposite ends of the slot 1 b in the casing part 1.

As will be apparent, from Figs. 2 and 5, due to the provision of the transverse slot 8e, the rocker member, when in one or other of its limit positions, is urged transversely and upwardly until the pivot pin 9 is stopped by one or other end of the inclined slot 8e. Thus, in operation, as the lever arm 8a is initially manually rocked, for example anticlockwise from the position shown in Fig. 2, the contact set 3, 6, and the cam surface 8d of the left- hand (relatively longer) transverse lever arm 8b will engage the cam surface 5b of the left-hand contact arm 5 flexing it into contact with the contact arm 2, whilst the corresponding cam surface 8d of the right- hand (relatively shorter) transverse lever arm 8c will be spaced from its associated contact arm 6.

Further rocking of the lever arm 8a, after flexing of the left-hand contact arm 5 is stopped by the stationary contact arm 2 as shown in Fig. 3, will cause the contact arm 5 to cam the rocker member to the right relative to the slot 8e, until the boss 8f and socket 1 Oa pass overcentre relative to the median plane, as shown in Fig. 4, whereafter the over-centre mechanism will resiliently snap the rocker member to its other limit position shown in Fig. 5, allowing the lefthand contact set 2, 5 to open. Manual rocking of the lever arm 8a in the opposite, i.e. clockwise direction from the position shown in Fig. 5, with the rocker member initially displaced to the right relative to the pivot pin 9, will, in an analogous manner, close the right-hand contact set 3, 6, then cam the rocker member bodily to the left, causing the over-centre mechanism to snap the rocker member to the position shown in Fig. 2, without actuating the lefthand contact set 2, 5, and allowing right-hand contact set 3, 6 to open.

The provision of the slot 8e, which allows the rocker member 8 not only to be rocked, but also to be transversely bodily or translationally displaced, by the over-centre mechanism, coupled with the camming action of the contacts, results in a particularly advantageous switch in which, upon actuation, one or other contact set is selectively momentarily closed or "flashed". The switch is relatively compact, positive in action, making it particularly suitable for small scale model railway track layouts, and is relatively simple to manufacture and assemble since it incorporates a minimum number of components.

6 When used to control the double-acting solenoid of a set of points of a model railway track layout, the common connector 7b is connected to the live side of a power supply, the connector 2-b is connected to one end of one of the solenoid windings, and the connector 3b is connected to one end of the other winding of the solenoid. The circuit is completed by a connection between the common ends of the solenoid windings and the power supply. Depending upon the direction in which the lever arm 8a is thrown, one or other of the solenoid windings will be energised, momentarily, irrespective of the speed at which the lever arm is thrown. The lever arm, when thrown, will remain permanently in its thrown position, serving at a useful indication to the operator as to the direction in which the movable point blades are set.

The rocker member, casing, and the socket and rod of the over-centre mechanism may be formed, for example molded, from a synthetic plastics material or materials. The contacts may be made from metal such as phosphorus bronze, which may be silver plated, and the pivot pin may be made of steel.

The switch may be designed so that the various components may be fitted to the rear casing part, and held in place by the front cover.

The switch may be located adjacent the point or solenoid actuating the point in the track layout, or may be mounted remotely, adjacent the control position of the operator. In the latter respect, a number of similar switches may be mounted side by side in a bank or console, plugged by their connectors into a common base or panel, wired to different points in the track layout.

It will be understood that various modifications may be made without departing from the scope of the present invention. For example, the pivot pin may be fixed relative to the rocker member, with the outer ends of the pin being mounted in transverse slots in the casing so as to accommodate the necessary transverse translational movement of the rocker member.

The cam surfaces of the rocker member andlor movable contact arms may have other configurations, or may be eliminated; for example the 7 transverse lever arms 8b and 8c may simply cooperate with straight or flat regions of the movable contact arms.

One or both of the contact sets may be configured so as to be normally closed instead of normally open, and the number of contact sets controlled and actuated by the rocker member may be changed. The movable contact arms may be replaced by contact members carried by the rocker arm.

Although, in the illustrated embodiment, the over-centre mechanism is triggered by the transverse displacement of the rocker member which occurs when one or other of the contact sets closes, this is not essential, and the transverse displacement could simply be triggered by the over-centre mechanism alone.

Other forms of over-centre mechanism may be employed, or the latter mechanism could be replaced by a toggle mechanism or other snap-acting trigger mechanism.

Although the switch is particularly suitable for use in controlling double- acting solenoids in model railway track layouts, it may be put to other uses where it is required to temporarily or momentarily close, or open, electrical circuits.

8

Claims

1. A rocker switch comprising: first and second sets of contacts, each contact set being switchable between first and second states; a rocker arrangement mounted for both pivotal and translational movement between the contacts sets; and an over-centre mechanism operable to resiliently urge the rocker arrangement, selectively, into a first pivotally and translationally displaced position or a second pivotally and translationally displaced position; the rocker arrangement, during pivotal displacement between the first and second positions, being translationally urged by the over-centre mechanism in a direction to cause one or other of the contact sets to change from its first to its second switched state, and thereafter being translationally displaced in a reverse direction to allow that contact set to return to its first switched state.

2. A switch as claimed in claim 1, wherein the first and second switched states are open-circuit and closed-circuit states respectively, and wherein each contact set, when changed from its first, open-circuit state to its second, closed-circuit state, acts on the rocker arrangement to initiate translational displacement thereof in the reverse direction, thereby to change the contact set back to its initial open-circuit state.

3. A switch as claimed in claim 1 or 2, wherein the rocker arrangement comprises a rocker member in the form of a generally inverted T-shaped operating lever, with the generally upright limb of the inverted T comprising an operating arm by which the lever may be manually rocked, and the transverse limb forming the base of the inverted T comprising opposed arms each extending generally towards, and being selectively cammingly cooperable with, a respective one of the contact sets.

4. A switch as claimed in claim 3, wherein the lever is mounted for rocking movement about a fixed axis defined by a pivot pin or the like which is located in a central slot in the lever base, the slot being elongated in the direction of the opposed, transverse arms, so that the lever may rock about the pin, and 9 also slide along the pin within the limits of the slot, generally transversely towards one or other of the contact sets, when the switch is operated.

5. A switch as claimed in claim 4, wherein the over-centre mechanism includes a compression spring, the upper end of which cooperates with an arm or boss dependent from the centre of the base of the lever, and the lower end of which is fixed at a location coincident with a median plane passing through the pivot pin, the over-centre mechanism acting to resiliently rockingly urge the lever about the pivot pin into one or other of its limit positions on opposite sides of the median plane.

6. A switch as claimed in claim 5, wherein the over-centre mechanism also acts on the lever to displace it bodily, generally transversely until the pivot pin selectively engages one or other end of the slot, depending upon whether the lever is in one or the other of its limit positions, whereby, as the lever is rocked from one towards the other limit position, initially against the force exerted by the over-centre mechanism, the lever engages and closes the contact set to which it is closer, by virtue of the transverse displacement, this engagement camming the lever in the opposite transverse direction, opening the previously closed contact set, and actuating, or assisting in actuating, the over-centre mechanism to cause it to urge the lever towards its other limit position.

7. A rocker switch constructed substantially as hereinbef ore described with reference to the accompanying drawings.