GB1599178A - Electric switch - Google Patents

Description

(54) AN IMPROVED ELECTRIC SWITCH (71) We, ARROW-HART (EUROPE) LIMITED, a British Company, of Plymbridge Road, Estover, Plymouth PL6 7PN, England, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to an electric switch.

According to the invention an electric switch includes a housing, an actuating member mounted for movement in first and second opposite directions within the housing between first and second end positions, an electrically-conducting connection element within the housing and movable by the actuating member into or out of electrical contact with switch contacts provided in the housing, a rotatable catch pivotally mounted on the actuating member, and, provided on the housing, a catch-engaging means, a fixed stop, and a movable abutment element resiliently urged into a set position for preventing the actuating member from being moved into its second end position, the rotatable catch being dimensioned and arranged so that (a) on movement of the actuating member in said second direction from its first end position, the catch engages the abutment element in its set position causing the catch to re-orientate itself so that subsequent movement of the actuating member in said first direction is limited by engagement of the catch with said catch-engaging means to locate the actuating member in a third position intermediate said first and second end positions, (b) on movement of the actuating member in said second direction from its third position to disengage said catch from said catch-engaging means, the catch engages the abutment element in its set position causing the catch to re-orientate itself to allow the actuating member to be moved in said first direction back to said first end position without the catch engaging said catch-engaging means, and (c) on movement of the actuating member in said second direction when the catch is in engagement with the abutment element in its set position, the catch is rotated against the fixed stop causing the abutment element to be resiliently urged out of its set position as the actuating member is moved into its second end position, the catch being so orientated, when the actuating member is in its second end position, that subsequent movement of the actuating member in said first direction is limited by engagement of the catch with said catch-engaging means to locate the actuating member in its third position.

The switch may be designed to provide any desired connection between said switch contacts in the various positions of the actuating member. Thus, in the case of a switch having three contacts, in said first end position of the actuating member the connection element may be out of contact with all the switch contacts, in. the second end position of the actuating member the connection element may be arranged to connect electrically all the three contacts and in the third position of the actuating member the connection element may be arranged to connect electrically two of the three contacts.

Suitably the electric switch includes resilient return means acting on the actuating member to urge the latter in the first direction towards its first end position. Typically the resilient return means comprises a compression spring mounted between the housing and the actuating member.

The abutment element may be pivotally mounted on the housing and may be resiliently urged into its set position by spring means acting on, or formed integrally with, said element.

The catch is preferably arranged so as to be turnable against a frictional force, the catch then only being movable out of a particular orientation by the application of a turning force which exceeds the frictional force. The frictional force is suitably chosen to be large enough to prevent the rotatable catch being re-orientated by gravitational forces or by shaking or jolting the switch.

The frictional force may be provided by mounting the catch in a frictional bearing or by arranging for the catch to frictionally engage the housing.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a partly-sectioned side view of part of an electric switch according to the invention, Figure 2 is a side view on the line Il-Il of Figure 1, and Figure 3 is a schematic perspective view showing the arrangements of the switch contacts and the connection element within the switch of Figures 1 and 2.

Figures 1 and 2 show a push-button electric switch, generally designated by the reference numeral 1, comprising a substantially parallelepipedic casing 2 housing spaced-apart and electrically-isolated switch contacts 3a, 3b and 3c, and a reciprocable actuating member 4 carrying an electricallyconducting connection element 5 having four flexible switch contact-engaging legs 5a, Sb, Sc and 5d (see Figure 3). The member 4 can be moved into any one of three operative positions, namely a first operative position (the position shown in Figure 2) in which the switch contact 3a is not electrically connected to either of the switch contacts 3b or 3c (the leg 5a is shown in contact with switch 3a although there need be no contact in this first operative position), the first operative position being at the limit of sliding of the actuating member 4 in a first sliding direction X; a second operative position (not shown) in which the legs 5a, 5b and Sc contact the switch contacts 3a, 3b and 3c, respectively, thereby electrically connecting the switch contact 3a to the switch contacts 3b and 3c, this second operative position being at the limit of sliding of the actuating member 4 in a second sliding direction Y opposite to the direction X; and an intermediate, third operative position, in which the legs 5a and 5b contact the switch contacts 3a and 3b, respectively, thereby electrically connecting the switch contact 3a to the switch contact 3b. The switch also comprises a mechanism, generally designated by the reference numeral 6, for enabling the actuating member 4 to be positioned in any of the aforesaid three operative positions. A push-button 7 is fixed to the actuating member 4 and can be pressed against a counteracting force provided by a compression spring 8, positioned between the casing 2 and the actuating member 4 and which resiliently urges the actuating member in the direction X towards its first operative position.

The mechanism 6 comprises a catch 9 rotatable about an axis 24 and consisting of a stem 10, rotatably mounted in a bore 11 provided in the actuating member 4, and a head portion 12 integrally formed with the stem 10 and having a pair of parallel side walls 13a and 13b and a pair of end walls 14, 15 each having a pair of inwardly-facing plane surfaces 14a, 14b (15a, 15b) which converge towards each other from the side walls 13a, 13b, respectively, and meet at a median plane 16 of the catch 9 at an angle of approximately 90ç. The head portion has four rounded corner edges 30 to 33 where the end walls 14, 15 meet the side walls 13a, 13b; the side wall 13a meeting surface 14a at corner edge 30 and meeting surface 15a at'corner edge 33 and the side wall 1 3b meeting surface 14b at corner edge 31 and meeting surface 15b at corner edge 32. The stem 10 passes through a slot 17 formed in a substantially flat side wall 18 of the casing 2. This slot 17, which is elongate in the sliding direction of the member 4 to allow the latter to slide between its first and second operative positions, opens into a recess 19 formed in the outer surface of the side wall 18 and provided with a pair of walls l9a and l9b which are arranged at right angles to each other and define catch-engaging means. A helical friction spring 27 is positioned to surround the portion of the stem 10 which passes through the slot 17 and to bear against confronting surfaces of the head portion 12 and the member 4. The spring 27 thus provides a certain degree of friction between the catch 9 and the actuating member 4 to prevent free turning of the catch 9 about its axis 24.

The mechanism 6 further comprises an abutment element 20 pivotally mounted on the side wall 18 and provided with an integrally formed, resilient arm 21, which abuts against a fixed stop 40 on the casing 2 to urge the element 20 into a set position (as shown in full lines in Figure 1), an abutment surface 26, and a catch-engaging surface 25 disposed at right angles to the surface 26. The mechanism 6 also comprises a further fixed stop 22 and a stop surface for the element 20 provided by a further wall 19c of the recess 19. Both the abutment element 20 and the stop 22 are positioned in the recess 19 but on opposite sides of a plane 23 which contains the axis 24 when the actuating member 4 slides between its first and second operative positions.

In operation of the switch, the push-button 7 is pressed in the direction Y to move the actuating member 4 out of its first operative position towards its second operative position. The catch 9 carried by the actuating member 4 is thus moved with the actuating member so that its corner edge 33 firstly abuts against, and then slides along in contact with, the abutment surface 26 of the abutment element 20 causing the catch 9 to turn in a clockwise direction about its axis 24.

If, after this clockwise turning of the catch 9, the pressure on the push-button 7 is released, the spring 8 moves the actuating member 4 back in the direction X towards its first operative position. However, the movement of the member 4 in the direction X is limited by the abutment of the corner edge 31 against the wall 19b causing the catch 9 to turn further in the clockwise direction so that the walls l9a and l9b abut the surfaces 14a and 14b, respectively, thereby locking the catch 9 in the upper of the two dashed line positions shown in Figure 1 and designated with the reference 9a, so that further movement of the catch 9 in the direction X is prevented. When the catch is locked in this position the actuating member 4 carrying the catch 9 is in its third operative position. It should be appreciated that in the foregoing description the distance that the actuating member 4 is first moved in the direction Y from its first operative position is not critical.

It is only necessary for the actuating member to be moved a sufficient distance for the catch to abut against the element 20 and turn a small amount, e.g. 2 or 3 degrees, in the clockwise direction. Once this initial small clockwise rotation of the catch has been achieved, further movement of the actuating member in the direction Y (even into its second operative position) will not prevent the actuating member from returning automatically to its third operative position on subsequent release of the pressure applied to the push-button 7. If it is only desired to move the actuating member 4 from its first operative position to its third operative position, the actuating member will normally be moved from its first operative position into a fourth position, between its second and third operative positions. When the actuating member 4 is in its fourth position the catch 9 adopts a position (shown in chain lines in Figure 1 and designated by the reference numeral 9b) in which the surfaces 25 and 26 of the element 20 contact the surfaces 15b and 15a, respectively, of the catch 9 and the fixed stop 22 contacts the side wall 13b of the catch 9. When the catch 9 is in its position 9b further movement of the actuating member 4 in the direction Y can only be achieved if an increased pressure is applied to the pushbutton 7 causing the catch 9 to be turned against the stop 22 thereby resiliently pivoting the abutment element 20 in the direction B out of its set position.

The actuating member 4 may be moved out of its third operative position by depressing the push-button 7 to move the actuating member, and the catch 9 carried thereby, in the direction Y until the corner edge 32 of the catch 9 is moved against the abutment surface 26 and the side wall 1 3b contacts the fixed stop 22, the catch 9 then being in the position shown in dashed lines in Figure 1 and designated by the reference 9c, and the actuating member being in a fifth position between its third operative position and its fourth position. On release of the pressure on the push-button 7, the spring 8 slides the actuating member 4 in the direction X back towards its first operative position. The wall 19b is in the path of the catch 9 as the actuating member 4 is moved in the direction X, but the catch is now so orientated that the catch-engaging means comprising the walls l9a, l9b cannot lock the actuating member in its third operative position but can only turn the catch 9 in the clockwise direction as the corner edge 30 and then the side wall 13a are moved against the catch-engaging means as the actuating member moves to its first operative position.

If, when the actuating member 4 is held in its fifth position by pressure applied to the push-button 7, an increased pressure is applied to the push-button 7, the actuating member can be moved in the direction Y into its second operative position. During this movement, since the side wall 13b of the catch 9 is against the stop 22, the catch 9 is forced to turn in a counterclockwise direction. As the catch turns in the counterclockwise direction its corner edge 32 presses against the surface 26 of the element 20 causing the latter to pivot in the direction B out of its set position. As the element 20 pivots in direction B the corner edge 32 is moved along the surface 26 towards the surface 25 until the abutment element 20 abuts against the wall 19c and comes to rest in the position shown in dotted lines in Figure 1, the actuating member in its second operative position and the catch 9 adopting the position shown in dotted lines in Figure 1 and designated by the reference 9d. The actuating member 4 only remains in the second operative position if the pressure applied to the push-button 7 is maintained.

If, however, the pressure on the push-button 7 is released, the actuating member moves back under the force of the spring 8 in the direction X until it is locked in its third operative position, as described previously, by engagement of the catch 9 with the catchengaging means comprising the walls 19a and 19b, and the abutment element 20 pivots back in the direction A to its set position.

Each time that the actuating member 4 is moved out of its first operative position into its third operative position so that the catch 9 is locked in its position 9a, and then is moved back to its first operative position (possibly via its second operative position), the catch 9 is turned 180 about its axis. However, since the catch 9 is symmetrical about its median plane 16, it will be appreciated that the electric switch 1 operates in the same manner whichever side wall 13a or 13b contacts the wall 19a when the member 4 is in its first operative position.

In the embodiment of the invention described the leg 5d of the connection element 5 makes no contact with any switch contact. Of course it should be realised that another switch contact could be provided if required to make contact with leg 5d.

In other embodiments of the above-described switch, the abutment element 20 could be urged into its set position by means of a spring. In addition the abutment element 20 could be linearly movable, instead of being pivotally movable, out of its set position.

Although the invention has been described with reference to a push-button electric switch, the invention is intended to embrace other types of electric switch, e.g. a pull switch.

WHAT WE CLAIM IS 1. An electric switch including a housing, an actuating member mounted for movement in first and second opposite directions within the housing between first and second end positions, an electrically-conducting connection element within the housing and movable by the actuating member into or out of electrical contact with switch contacts provided in the housing, a rotatable catch pivotally mounted on the actuating member, and, provided on the housing, a catchengaging means, a fixed stop, and a movable abutment element resiliently urged into a set position for preventing the actuating member from being moved into its second end position, the rotatable catch being dimensioned and arranged so that (a) on movement of the actuating member in said second direction from its first end position, the catch engages the abutment element in its set position causing the catch to re-orientate itself so that subsequent movement of the actuating member in said first direction is limited by engagement of the catch with said catch-engaging means to locate the actuating member in a third position intermediate said first and second end positions, (b) on movement of the actuating member in said second direction from its third position to disengage said catch from said catchengaging means, the catch engages the abutment element in its set position causing the catch to re-orientate itself to allow the actuating member to be moved in said first direction back to said first end position without the catch engaging said catch-engaging means, and (c) on movement of the actuating member in said second direction when the catch is in engagement with the abutment element in its set position, the catch is rotated against the fixed stop causing the abutment element to be resiliently urged out of its set position as the actuating member is moved into its second end position, the catch being so orientated, when the actuating member is in its second end position. that subsequent movement of the actuating member in said first direction is limited by engagement of the catch with said catchengaging means to locate the actuating member in its third position.

2. An electric switch according to claim 1 having three fixed switch contacts arranged so that in said first end position of the actuating member the connection element is out of contact with at least two of the switch contacts, in the second end position of the actuating member the connection element is arranged to connect electrically all the three switch contacts and in the third position of the actuating member the connection element is arranged to connect electrically two of the three switch contacts.

3. An electric switch according to claim 1 or 2, including resilient return means acting on the actuating member to urge the latter in the first direction towards its first end position.

4. An electric switch according to claim 3, in which the resilient return means comprises a compression spring mounted between the housing and the actuating member.

5. An electric switch according to any one of the preceding claims, in which the abutment element is pivotally mounted on the housing and is resiliently urged into its set position by spring means acting on, or formed integrally with, said element.

6. An electric switch according to any one of the preceding claims, in which the catch is arranged so as to be turnable against a frictional force, the catch only being movable out of a particular orientation by the application of a turning force which exceeds the frictional force.

7. An electric switch according to claim 6, in which the frictional force is provided by mounting the catch in a frictional bearing.

8. An electric switch according to claim 6, in which the frictional force is provided by spring means urging the catch into frictional engagement with the housing.

9. An electric switch constructed and arranged substantially as herein described with reference to, and as illustrated in, Figures 1 to 3 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. In other embodiments of the above-described switch, the abutment element 20 could be urged into its set position by means of a spring. In addition the abutment element 20 could be linearly movable, instead of being pivotally movable, out of its set position. Although the invention has been described with reference to a push-button electric switch, the invention is intended to embrace other types of electric switch, e.g. a pull switch. WHAT WE CLAIM IS

1. An electric switch including a housing, an actuating member mounted for movement in first and second opposite directions within the housing between first and second end positions, an electrically-conducting connection element within the housing and movable by the actuating member into or out of electrical contact with switch contacts provided in the housing, a rotatable catch pivotally mounted on the actuating member, and, provided on the housing, a catchengaging means, a fixed stop, and a movable abutment element resiliently urged into a set position for preventing the actuating member from being moved into its second end position, the rotatable catch being dimensioned and arranged so that (a) on movement of the actuating member in said second direction from its first end position, the catch engages the abutment element in its set position causing the catch to re-orientate itself so that subsequent movement of the actuating member in said first direction is limited by engagement of the catch with said catch-engaging means to locate the actuating member in a third position intermediate said first and second end positions, (b) on movement of the actuating member in said second direction from its third position to disengage said catch from said catchengaging means, the catch engages the abutment element in its set position causing the catch to re-orientate itself to allow the actuating member to be moved in said first direction back to said first end position without the catch engaging said catch-engaging means, and (c) on movement of the actuating member in said second direction when the catch is in engagement with the abutment element in its set position, the catch is rotated against the fixed stop causing the abutment element to be resiliently urged out of its set position as the actuating member is moved into its second end position, the catch being so orientated, when the actuating member is in its second end position. that subsequent movement of the actuating member in said first direction is limited by engagement of the catch with said catchengaging means to locate the actuating member in its third position.

2. An electric switch according to claim 1 having three fixed switch contacts arranged so that in said first end position of the actuating member the connection element is out of contact with at least two of the switch contacts, in the second end position of the actuating member the connection element is arranged to connect electrically all the three switch contacts and in the third position of the actuating member the connection element is arranged to connect electrically two of the three switch contacts.

3. An electric switch according to claim 1 or 2, including resilient return means acting on the actuating member to urge the latter in the first direction towards its first end position.

4. An electric switch according to claim 3, in which the resilient return means comprises a compression spring mounted between the housing and the actuating member.

5. An electric switch according to any one of the preceding claims, in which the abutment element is pivotally mounted on the housing and is resiliently urged into its set position by spring means acting on, or formed integrally with, said element.

6. An electric switch according to any one of the preceding claims, in which the catch is arranged so as to be turnable against a frictional force, the catch only being movable out of a particular orientation by the application of a turning force which exceeds the frictional force.

7. An electric switch according to claim 6, in which the frictional force is provided by mounting the catch in a frictional bearing.

8. An electric switch according to claim 6, in which the frictional force is provided by spring means urging the catch into frictional engagement with the housing.

9. An electric switch constructed and arranged substantially as herein described with reference to, and as illustrated in, Figures 1 to 3 of the accompanying drawings.