US3427415A

US3427415A - Electric switches

Info

Publication number: US3427415A
Application number: US637652A
Authority: US
Inventors: David Alan Avner
Original assignee: Girling Ltd
Current assignee: Girling Ltd
Priority date: 1967-05-11
Filing date: 1967-05-11
Publication date: 1969-02-11
Anticipated expiration: 1986-02-11

Description

Feb. 11, 1969 0. A. AVNER [3,

ELECTRIC SWITCHES 7 Filed May 11, 1967 v Sheet of z /5 v v I Feb. 11, 1969 I AVNER 3,427,415 I ELECTRIC SWITCHES Filed May 11, 1967 Sheet 2 of 2 United States Patent 3 Claims ABSTRACT OF THE DISCLOSURE An electrical switch having three fixed contacts and a bridging member movable through a lost motion linkage by a three position operating lever between first and second positions where it bridges respectively the first and second fixed contacts and the second and third fixed contacts. The operating lever having a first extreme position wherein the bridging member occupies its first position, a second extreme position wherein the bridging member occupies its second position, and a central position wherein the bridging member occupies its first or second position according to the previous position of the operating member.

This invention relates to electrical switches.

An electrical switch according to the invention includes, first, second, and third fixed contacts, a conductive bridging member movable between first and second positions in which it completes circuits between the first and second fixed contacts and the second and third fixed contacts respectively, a three position operating member movable from a central position to extreme positions in which the bridging member occupies said first and second positions respectively and a lost motion connection between the operating member and the bridging member which permits the operating member to occupy said central position while the bridging member occupies either of its positions according to the previous position of the operating member.

One example of the invention is illustrated in the accompanying drawings wherein FIGURE 1 is a sectional view of a switch, FIGURES 2, 3, 4 and 5 are diagrammatic views illustrating respectively four operating positions of the switch shown in FIGURE 1, and FIGURE 6 is a diagrammatic view of a road vehicle body height adjusting system utilizing the switch shown in FIGURES 1 to 4.

Referring first to FIGURE 1 the switch 9 includes a casing -10, housing three fixed contacts 11, 12, 13. Slidably supported in the casing =10 is a conductive bridging member 14 movable between a first position in which it bridges the contacts 11, 12 and a second position in which it bridges the contacts 12, 13 the member .14 having outwardly directed tags 14a which engage in grooves 10a in the walls of the casing 10. Pivotally engaged with the casing is an operating member .15 including a lever portion 16, which extends from the casing, and a further portion 17, integral with the portion 16, which extends into the casing. The portion 17 is hollow and has slidably supported therein a plunger 18 which engages one of a pair of depressions :19, 21 formed in the upper surface of the member 14. The plunger is urged into engagement with the member 14 by a spring 22 housed with the portion 17.

Referring now to FIGURES 2 to 5, in FIGURE 2 the circuit between the contacts 11, 12 is completed, the member is vertical and the plunger 18 is engaged in the depression 21. If the member 15 is now moved in a clockwise direction, the plunger .18 will be caused to ride out of the depression 21 and into the depression 19 (FIGURE 3). Thus the plunger 18 and the depressions 19, 21 constitute a lost motion connection between the member 14 3,427,415 Patented Feb. 11, 1969 and the member 15. In order to break the circuit between the contacts 11, 12 and complete the circuit between the contacts .12, 13 the member -15 is moved in a counter clock-wise direction and as the member 15 moves from an inclined position to a vertical position the member 14 is moved to the right to complete the circuit between the contacts 12, .13 (FIGURE 4). Further movement of the member 15 in a counter clock-wise direction causes plunger 18 to ride out of the depression 19 and back into the depression 21 (FIGURE 5) whereafter movement of the member 15 in a clock-wise direction returns the switch to the position shown in FIGURE 2 to break the circuit between contacts 12, :13 and complete the circuit between contacts 11, 12. Thus the member 15 can assume any one of three positions, a pair of extreme positions wherein the member 14 completes the circuit between the contacts -11, 12 or the contacts .12, 13 respectively and a mid-position wherein the member 14 completes either of the circuits, the circuit completed in this position being the circuit other than the one which was completed in the previous position of the member 14. The switch therefore has what can be termed a memory, and this feature makes the switch useful in a number of applications, one of which is shown in FIGURE '6.

Referring now to FIGURE 6, the switch 9 has ganged thereto a second switch 24 having three positions corresponding to the three positions of the switch 9, a pair of extreme on positions and an intermediate 01f position. The switch 24 controls operation of a pump 25 which supplies fluid through a two way valve 26 to a hydraulic apparatus positioned on a road vehicle to adjust the height of the body of the vehicle with respect to the wheels of the vehicle. The valve 26 has a raise position and a lower position and is movable between the two positions by a pair of solenoids 27, 28. The contact 12 of the switch 9 is connected to the input terminal of the switch 24 and so is live in use. The contacts 11, :13 of the switch are connected through the solenoids 27, 28 and two pairs of

contacts

29, 21 and 32, 33 respectively the contacts 29, 21 being closed only when the valve 26 is in its lowering position while the

contacts

32, 33 are closed only when the valve 26 is in its raised position.

Assuming that the system has previously performed a raising operation and has then been switched off, then the system will be in the position shown in FIGURE 6.

If now a lowering operation is required the member 15 of the switch 9 is moved in a clock-wise direction and since the contacts 11, 12 are already bridged the plunger 18 rides into the depression 19, since the switch 24 is ganged to the switch 29 the switch 24 is moved to an operative position and the pump 25 is operated. The valve 26 is already in its lower position and so fluid flows in the system to lower the body of the vehicle relative to the vehicle wheels. In order to stop the lowering operation the member 15 is returned to a central position thereby moving the member 14 to a position bridging the contacts 12, 13 and moving the switch 24 to its off position. When the contacts 12, 13 are bridged the circuit to the solenoid 27 is completed since the contacts 29, 31 are closed and valve 26 is therefore moved to its raise position opening the contacts 29, 31 and closing the

contacts

32, 33.

In order to perform a raising operation the member 15 is moved in a counter clock-wise direction which moves the switch 24 to an on position and since the contacts 12, 13 are now bridged the plunger 18 will be caused to ride out of the depression 19 and into the depression 21.

Since the switch 24 is ganged to the switch 9 the pump 25 will be operating so that fluid flows in the system to raise the body of the vehicle relative to the vehicle wheels. In order to stop the raising operation the member 15 is returned to its mid-position thereby moving the switch 24 to its 01f position and moving the member 14 to bridge the contacts 11, 12 thereby completing the circuit to the solenoid 28 and returning the system to the position shown in FIGURE 6.

It will be appreciated that when the contacts 11, 12 are bridged the solenoid 28 ensures that the valve 26 is in its lower position wherein the circuit to the solenoid 28 is broken. Similarly when the contacts 12, 13 are bridged the solenoid 27 ensures that the valve 26 is in its raising position. Thus if in use the valve becomes moved from its one position to its other position without the switch 9 being moved as could occur for example through vibration, then the contacts 29, 31 or the

contacts

32, 33 will be closed and the solenoid 27 or the solenoid 28 will be energised to return the valve to its original position.

Thus the valve 26 is always maintained in its raise or its lower position dependent on the position of the switch 9.

The switch 9 and the switch 24 preferably have a cornmon casing and a common operating member.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. An electric switch comprising a body member; first, second and third fixed contacts mounted in said body; a slidable conductive bridging member in said body movable between stop means defining first and second positions wherein said bridging member completes circuits between said first and second contacts and said second and third contacts respectively, said bridging member having two depressions in it; a three position operating member mounted in said body and capable of being operated from without said body; and connection means operably positioned between said operating member and said bridging member and comprising a resilient part engageable in said depressions, lost motion occurring when said bridging member is engaged by said stop means and movement of said operating lever causes said resilient part to disengage from one of said depressions and engage the other depression without moving said bridging member.

2. An electric switch as claimed in claim 1 wherein said resilient part consists of a plunger spring biased toward said bridging member.

3. An electric switch as claimed in claim 1 in combination with a three position switch ganged to said electric switch so as to be operable in response to the movements of said operating member.

References Cited UNITED STATES PATENTS 8/1953 Bollhoefer 200-76 X 1/1963 Gluck 20016 US. Cl. X.R. 20068, 16, 164