IE43595B1 - Electric switches - Google Patents

Abstract

1534706 Mechanical switches D A SWANN 21 Nov 1975 [25 Nov 1974 3 Dec 1974] 48027/75 Heading H1N The subject matter of this Specification is similar to that described in Specification 1,534,705, but the claims are concerned, with an electrical switch including a movable contact which is slidable over and pivotable about a fixed contact. In alternative embodiments described, the latch mechanism can be omitted and the movable contact may be provided with a depression (37) (Fig. 5, not shown) instead of an abutment, in which ease each of the fulcrum contacts is provided with a slot (Fig. 5a, not shown) to enable the projection defined by the depression (37) to pass.

Description

This invention relates to electric Switches.

It also relates to contact bridging members for electric switches.

The present invention provides an electric switch having a mechanism comprising an acutator, a contact bridging member capable of being moved along a path by the actuator, and two spaced apart electric contacts arranged along the path wherein one of the contacts functions, in use, as a fulcrum, the actuator applying force to the member at an area intermediate its ends and on one side thereof, the member having an opposite side which, in use, engages the contacts, the opposite side being comprised of first and second surface portions which are at an angle to one another diverging from the path, the surface portions, in a first position of the member, engaging respective ones of the contacts and being inclined to a straight line joining surfaces of the contacts which are engaged by the member when in the first position and the area being in the first position located to the side of the fulcrum adjacent the other of the contacts whereby part of the member nests closely with and between the contacts, force being applied in a direction urging the part into such besting relation and wherein the member is.so shaped and located and the switch is constructed and arranged such that the member 1s movable, from the first position, slideably with respect to the contacts and in so doing the trailing one of the surface portions moves with a component of motion in the direction, of the force such that the - 2 member initially rotates in one direction, tiie part moves to become relatively less nested and does so against the action of the force tending to restore it to the nested condition, the area approaches the fulcrum, and thereafter after the area has passed the fulcrum, the member pivots about the fulcrum in the opposite direction whereby it disengages from the first contact.

Preferably the switch includes an additional electric contact on the side of the fulcrum opposite to the first contact and with which u.ie additional electric contact the leading end of the contact bridging member is brought into contact in consequence of the aforesaid 15 pivoting. It is preferred that the additional electric contact and the fulcrum are positioned such that tne bridging member will similarly nest therewith in a second position and the member is similarly slideable with respect to the additional electric contact and the fulcrum similarly 20 . . . .initially rotates in onedirection and is similarly pivotable about the fulcrum in moving from the second position to the first position.

In another instance, in addition to the fulcrum, hereinafter called the first folcrum, the switch includes a second fulcrum to the side of the first fulcrum opposite to the first contact and an additional electric contact to the side of the second fulcrum opposite to the first fulcrum and wherein the part will similarly nest with the first and second fulcrums in a second position and with the additional electric contact and the second fulcrum in a third position and the member is similarly slideable v/ith respect to the first and second fulcrum and the additional electric contact and tiie second fulcrum, similarly initially rotates in one direction and is similarly pivotable about the second fulcrum in moving from the second position to the third position and from the third position to the second position. The second fulcrum is an electric contact.

In some aspects it will be realized that the member can be likened to a boat lying in a trough between wave crests (adjacent contacts) rising up at its leading end and lowering at its trailing end in passing over the middle crest (the fulcrum) and then sliding down into the next trough (the space between the fulcrum and the other contact). This movement of the boat enables very positive making and breaking contact.

Further it is to be particularly noted that the mechanism can be applied to an indefinite number of contacts which may define an arcuate or circular path with the member within the arc or circle.

A large number of other arrangements are possible when the contacts·, lie in a plane and .Examples ’ include application in rocker switches, push-pull switches, sliding switches and rotary switches.

In a modification, the leading end of the member, in moving away from the path, contacts a body member which will exert a. force' on the leading end until such time as the point passes the ful'crum. This may assist operation - 4 43595 The member is shaped to have portions which are inclined away from the path and which inclined portions contact any two adjacent contacts when the member is located therebetween. This arrangement results in a more stable location of the fulcrums, than if the member was flat. In one aspect of this, the member is arcuate and in another aspect the member comprises an intermediate portion and flat ends which are inclined to the intermediate portion and in these aspects the stability ' of location will be dependent on the shape of the arc and in particular the radius thereof if the arc is an arc of a circle or on the angles that the flat ends make with the intermediate portion.

As an alternative, or preferably additional, means of stabilizing the location of the member, particularly when in contact with both of the fulcrums, a car. and a cam follower may be provided, one of which is carried by the actuator and the other of which is carried by a casing for the switch. This use of a cam and cam follower is applicable in other aspects of this invention.

A particular advantage achievable as a result of this invention is that by choosing the shape of the member and the positioning of the contact which it contacts it will generally be found to be possible to comply with standards set by electric approval authorities concerning minimum spacings of electrical conductors. In this respect, it is well known that many prior art switches tend to arc immediately before. 43S3S Embodiments of the invention will now be described by way of example, with reference to the accompanying drawings in which :Figure 1 is a schematic elevational view of one switch hiechanism which is useful in certain aspects of this invention.

Figures 2 to 4 are a schematic elevational view of another switch mechanism which is useful in certain aspects of this invention and show the mechanism in various stages of operation, Figure 5 is a perspective view of a contact bridging member which is useful in certain aspects of this invention, Figure 6 is a sectional view taken along the line 6-6 in Figure 5, Figure 7 is a perspective view of an electrical contact which is useful in certain aspects of this invention, Figure 8 is a sectional view of another contact bridging member which is useful in certain aspects of this invention, Figure 9 is a schematic exploded perspective view of another switch mechanism in accordance with this invention, Figure 10 is a cross-section of the mechanism shown in Figure 9, Figure 11 is a perspective view of a specific switch in accordance with this invention which embodies the mechanism of Figure 1 but which is modifiable, to have a mechanism inter alia as shown in Figures 2 to 4, Figure 12 is a cross-section through the switch of 3 5 Figure 11, Figure 13 is another cross-section through the switch of Figure 11, Figure 14 is another cross-section through the switch of Figure 11 and is a view taken along the line 14-14 in Figure 13, Figure 15 is a schematic drawing exemplifying one manner of use of the switch shown in Figures 11 to 14, Figure 16 is a perspective view of another specific switch in accordance with this invention which embodies the mechanism of Figures 2 to 4, view on line 17-17 Figure 17 is a cross-sectional in Figure 16, Figure 18 is a cross-sectional view on line 18-18 in Figure 17, Figure 19 is a developed cross- -sectional view of the switch of Figure 16 r Figure 20 is a cross-sectional detail of the switch of Figure 16, and Figure 21 is a cross-section taken along the line 21-21 in Figure 17.

The mechanism schematically shown in Figure 1 comprises four contacts (21,22,23 and 24) and of them the upper ends of contacts 22 and 23 lie in a first plane below a second plane in which lie the upper ends of contacts 21 and 24.

A contact bridging member 30 is provided and is biassed downwardly in the direction of arrow 31 by means which is not shown and which acts on point 32. Bridging member 30 can also be moved in the direction of arrow 33 (and in the reverse direction) by means which also is not shown. As shown in Figure 1, bridging member 30 bridges contacts 21 and 22.

It is also to be noted that bridging member 30 is curved and that the radius of curvature of the bridging member 30 is less than the radius of a circular arc (indicated by dotted line 36) which intersects the upper ends of contacts 21, 22, 23 and 24.

When bridging member 30 is moved in the direction of arrow 33 it will slide on contacts 21 and 22 and in so doing the right and left hand ends (in Figure 1) will initially rotate anti-clockwise and respectively rise and fall so that although the right hand end is being moved towards contact 23 it also has a component of motion away from contact 23. This motion proceeds until point 32 passes contact 22 whereupon the bias in the direction of arrow 31 will cause the bridging member 30 to pivot about contact 22 with contra-rotation of the ends of member 30 to the rotation described above so that the right hand end comes into contact with contact 23 and the left hand end comes out of contact with contact 21 and so that contacts 22 and 23 are bridged. Continued movement in the direction of arrow 33 will cause contacts 23 and 24 to be bridged and contact with contact 22 to be broken.

The effect of the bias on point 32 will be discussed in respect of Figures 2 to 4.

The mechanism shown in Figure 1 is particularly effective as a centre-off switch when contacts 22 and 23 43593 are active and has a position on each side of centre in which current will flow to contact 21 or 24.

Other arrangements of the mechanism shown in Figure that are particularly desirable are those where a number of such mechanisms are arranged side-by-side to be operated by a common actuator. An example of this is that the circuit of Figure 18 (to be discussed in detail later) can be achieved.

In the mechanism shown in Figures 2 to 4 similar parts are represented by the same reference numerals as used in respect of Figure 1. It is to be noted that Figures to 4 have been drawn to show stages in the operation of the mechanism, the whole mechanism being schematically shown in Figure 4. It is to be noted also that the upper ends of contacts 21, 22, 23 and 24 all lie in one and the same plane.

The manner of operation of the mechanism shown in Figures 2 to 4 is similar to that of Figure 1 but is set out below.

From the position shown in Figure 2 with bridging member 30 evenly located between contacts 21 and 22 it is movable to the right in the direction of arrow 33. In so moving, bridging member 30 slides on contacts 21 and 22, rotates as described with respect to Figure 1 and it is to be noted that point 32 moves from initially below the aforesaid plane and rises to the level of the aforesaid plane against the bias which tends to act against such movement.

The bias also, while point 32 is between contacts 21 and 22, will cause end 35 of the bridging member 30 to approach the aforesaid plane and, in the sliding, end 34 is, as a consequence, caused to rise further above the aforesaid plane until the position shown in Figure 3 is reached when end 34 is above but not in contact with contact 23.

This being above but not in contact with contact is considered highly desirable as there is little prospect of arcing but switching can be rapidly effected.

Continued movement in the direction of arrow 33 will cause point 32 to pass contact 22 whereupon the bias will cause end 34 to fall (see Figure 4) to contact contact 23 and end 35 will rise to break contact 21.

Thus, as shown in Figures 2 to 4, (the mechanism of Figure 1, as mentioned before, operates similarly), the bridging member 30 is akin to a boat rising up on crests and descending into troughs with its leading end rising to locate above each crest before falling to contact that crest.

As mentioned, Figures 1 and 2 to 4 are schematic and it will be realized that an enormous number of switches 1 can be made which embody the mechanism and without wishing to be restricted applicant mentions rocker, sliding and rotary switches all of which can come in various forms.

As further exemplification applicant mentions that the mechanism of Figure 1 can be applied to simple rocker switches having three or more fixed contacts or to rotary switches having a plurality of fixed contacts which extend radially, which define a circular path, and· which have axially extending surfaces which are contacted by bridging member 30.

The mechanism of Figures 2 to 4 is considered by applicant to be particularly meritorious as sliding switches of any length can be made and also rotary switches can also be made.

The contact bridging members shown in Figures 5 and 6, and Figure 8 ore specific examples of contact bridging members which can be used in the mechanism of Figures 1 and 2 to 4.

The contact bridging member 40 shown in Figures 5 and 6 is curved along its length and has a depression 37 in one side with a corresponding projection on the other side. Because of that projection the member 40 needs to be used with contacts having a slot 106 therein, such as is shown in Figure 7. an The contact bridging member 50 shown in Figure 8 has intermediate portion and two end portions which are upwardly inclined to the intermediate portion. The member 50 also has a depression 37 but it is formed in a bossed up portion so that there is no projection below the plane of the lower surface of the intermediate portion.

Another bridging member which is particularly useful for rotary switches is the member 70 which can be seen in plan in Figure 18 wherein it is seen to be curved, and in vertical cross-section in Figure 19, wherein it is seen to also be arcuate in respect of that view.

An example of a switch mechanism embodying the mechanism of Figure 3 is sho*n schematically in Figures 9 and 10 and once again like reference numerals denote Similar parts excepting that it is to be noted that a further fixed contact 25 is provided, bridging member 30 is dish 43&S % shaped and has a depression 37 in its centre which serves as a locant for means for biassing it in the direction of arrow 31, and a linearly extending fixed contact 26 is also provided.

In the arrangement shown in Figures 9 and 10 the bridging member 30 makes sliding contact at all times with contact 26 and engages contacts 21 to 25 in like manner as described with respect to Figures 2 to 4. Thus, at any one time, a circuit is established between contact 26 and any two adjacent ones of contacts 21 to 25.

A variant on the switch mechanism shown in Figures 9 and 10 has contacts equivalent to 21 to 25 which have concave upper surfaces arranged at right angles to the concave surfaces shown in Figure 9 and extending in a plane parallel to contact 26 so that, as well as forming circuits between contact 26 and any two adjacent ones of contacts 21 to 25 in a similar manner as described with respect to Figures 9 and 10, it is also possible to form circuits between contact 26 and any one of contacts 21 to 25.

The arrangements shown in Figures 9 and 10 and the variant thereon are particularly suitable for use in rotary switches in that if contact 26 is made into an annulus and additional contacts like 21 to 25 are provided and arranged in a circle the switch is converted from being linear to rotary.

The specific switch in accordance with this invention which is shown in Figures 11 to 14 uses the mechanism of Figure 1. As before, like reference numerals denote similar parts η ρ* η t» Ο «4 «ί ΰ The switch comprises a body 80 in which an actuator 81 is pivotally mounted by means of pivot pins 82. The body carries contacts 21 to 24 and it is to be noted that contacts 21 and 24 lie at a higher level than contacts 22 and 23. The body also has contacts 85, 86, 87 and 88 which lie behind, respectively/, contacts 21, 22, 23 and 24 in Figure 13 and one of which, 85, is shown in Figure 14.

Actuator 81 is provided with a pin 89 which is slideably received in a bore 92 and is spring loaded by a spring 94. The pin 89 follows a cam surface 97 formed on an intermediate wall in the body 80 and co-operates with a depression 99 in that cam surface to stabilize the actuator 81 when it is in a central position.

The bridging member used in this instance for contacts 21 to 24 is the member 40 shown in Figures 5 and 6 and it is to be noted that it has the depression 37 in its centre which accommodates a pin 102 carried in a bore 103 in actuator 81 and v/hich pin 102 is spring loaded by a spring 104. The bridging member for contacts 85 to 88 is of the same shape and is identified by reference numeral 40a. It, too, has a depression 37a equivalent to 37 for a similar reason.

To enable depressions 37 and 37a to pass, contacts 22, 23, 86 and 87 are slotted at 106 as is best seen in Figure 7.

The manner of operation of the switch shown in Figures 11 to 14 is essentially the same as that of the mechanism shown in Figure 1 and it will not be further explained excepting that it is to be noted that pin 102 exerts the bias in the direction of arrow 31 and enables movement in the direction of arrow 33 and the opposite direction.

The switch shown in Figures 11 to 14 can be used 5 in a progressive circuit which hitherto has only been achievable at great expense. That circuit is shown in Figure 15 where each of contacts 21 to 24 and 85 to 88 is represented by a circle, A means active or line supply and is connected to contacts 21, 24 and 87 and lines under 40 and 40a LO indicate circuit conditions with an arrow indicating current passing and a dash line indicating no current passing.

The switch of Figures 11 to 14 in the circuit shown in Figure 15 acts as a progressive switch and in a first position (the position shown in Figure 13) current flows L5 between contacts 21 to 22 but not between contacts 85 and 86.

In a second (central) position, current does not flow between contacts 22 and 23 but does flow between contacts 86 and 87. In a third position (bridging members 40 and 40a ,θ in contact with, respectively, contacts 23 and 24, and 87 and 88) current flows between contacts 23 and 24, and 87 and 88.

The switch shown in Figures 11 to 14 can be modified to operate as does the mechanism of Figures 2 to 4 if all contacts lie in the same plane but this is not preferred as actuator 81 causes pins 102 to move arcuately.

The switch shown in Figures 11 to 14 can also be □ 5 3 s modified by omitting contacts 22 and 23, and 86 and 87 by inserting a contact in groove 100b (and a corresponding contact in a corresponding groove with respect to bridging member 40a). When so modified the switch becomes a two position switch and in this instance the pin 89 is best omitted. Grooves 100a and 100c can be used to receive other contacts to thus enable different switching operations.

The switch shown in Figures 16 to 21 is an application of the mechanism shown in Figures 2 to 4 and parts similar to those of Figures 2 to 4 and 11 to 14 bear like reference numerals.

The switch shown in Figures 16 to 21 has a body 80, an actuator 81 which comprises a knob 110 and a shaft 111 which passes through a cover 114 and which carries a block 113. The block is also supported by a post arising within the body 80.

The cover 114 for the body 80 has a series of indentations 115 arranged in a circle on its inner surface. The block 113 has two bores 116 arranged diametrically opposite 20 one another and the bores locate spring loaded balls 117 which serve to locate block 113 in any one of twelve different angular orientations.

The body 80 has twelve fixed contacts therein which are similar in form to the contacts of the switch shown in Figures 11 to 14 (see also Figure 7) but which are arranged in a circle with their upper ends 119 extending radially and in a plane. Only two of those contacts (21 and 22) are specifically numbered. 13595 As bridging members a member 70 is used and a simi1ar-member also identified by 70.

It is to be noted that as well as being arcuate when seen in cross-section (see Figure 19) in a similar manner to contact 40, bridging taember 70 is also arcuate when seen in plan (see Figure 18).

Block 113 carries pins 102 in holes 103 and the pins 102 are spring loaded by springs 104.

It is not considered necessary to describe the 0 operation of the switch shown in Figures 16 to 21; the manner of operation being similar to the mechanism shown in Figures 2 to 4 with the exception that bridging members move in a circular rather than a linear path. However, it is also to be noted that ends 34 and 35 of bridging member 70 contact 'a body member in this embodiment of the invention provided by the underside of block 113 and that this is belieVed to aid the operation in that a strong downward bias is exerted as pins 102 pass each of the contacts.

The switch shown in Figures 16 to 21 is a double pole twelve positions switch. It operates in an excellent 0 manner and is extremely cheap to manufacture.

In some constructions in accordance with Figures to 21 it is desirable that pins 102 are electrically conducting and that current is supplied thereto.

In a particular construction in accordance with □ Figures 11 to 14 all contacts are 1mm. thick, contacts 21 and 22 and 23 and 24 are spaced about 6.5 or 5.5mm. apart and contacts 22 and 23 are spaced about 6.5, 6.0 or 5.5mm. apart. (Spaces between adjacent surfaces, not centres). 435θ5 The upper surfaces of contacts 22 and 23 lie in a plane spaced 2.12mm. from a plane including the upper surfaces of contacts 21 and 24 and the distance from pin 82 to the upper surface of contact 22 is 41mm. The radius of outside curvature of contact bridging member 40 is 0.359 inch (about 9mm.) and its chord length .is about 15 mm. and thus the arc subtended is about 80° and has a length oi about 20mm.

In general, for constructions such as is shown 10 in Figures 11 to 14, it is preferred that the radius of curvature of the bridging member is from l/5th to 2/3rds, preferably l/4th to l/3rd, the radius of movement of the end of the actuator. For constructions in which the upper surfaces of the contacts lie in the same plane it is preferred that the radius of curvature of the bridging member is from equal to or greater than the spacing of the contacts and preferably is no more that 4 times the spacing.

In general, the curvature of the bridging member should be such as to give the indexing required, or if this is not particularly required, must be at least such as v/ill allow it to pass from contact to contact having regard to the particular disposition of the contacts; thus for contacts with ends lying on a circle as in Figures 11 to 14 the radius of curvature of the contact bridging member is greater as compared to the alternative when they lie all in one plane. Further, consideration should be had to electric approval authorities regulations some of which require a minimum 3mm. gap under certain circumstances; and it is mentioned in this respect that the location of end 34 above but not in contact with contact 23 mentioned in respect of Figures 2 to 4 is easily achievable to the extent of a 3mm. spacing.

In modifications of the constructions above described 5 the contacts may have enlarged contact surfaces, such as by bending them, to provide greater areas for contact. in the specific constructions described above all of tiie contact bridging members have the depression 37 and corresponding projection on the other side of the contact bridging members and use fixed contacts with slots 106 as shown in Figure 7. While effective for many purposes, these slotted contacts do not have the current load carrying capacity of plain ended contacts, tend to promote arcing and seem to result in decreased switch life. If desired, alternatives such as the non-planar contact bridging members and terminals sho”?' in British latent Specification No. 1,534,705. may be used.

Claims (16)

1. WHAT WE CLAIM IS:

1. An electric switch having a mechanism comprising an actuator, a contact bridging member capable of being moved along a path by the actuator, and two spaced apart electric contacts arranged along the path wherein one of the contacts functions, in use, as a fulcrum, the actuator applying force to the member at an area intermediate its ends and on one side thereof, the member having an opposite side which, in use, engages the contacts, the opposite side being comprised of first and second surface portions which are at an angle to one another diverging from the path, the surface portions, in a first position of the member, engaging respective ones of the contacts and being inclined to a straight line joining surfaces of the contacts which are engaged by the member when in the first position and the area being in the first position located to the side of tne fulcrum adjacent the other of the contacts whereby part of the member nests closely with and between the contacts, the force being applied in a direction urging, the part into such nesting relation and wherein the member is so shaped and located and the switch is constructed and arranged such that the member is movable, from the first position, slideably with respect to the contacts and in so doing the trailing one of the surface portions moves with a component of motion in the direction of the force such that the member initially rotates in one direction, the part moves to become relatively less nested and does so against the action of the force tending to restore it to the nested condition, the area approaches the fulcrum, and thereafter after the area has passed the fulcrum the member pivots about the fulcrum in the opposite direction 435S5 whereby it disengages from the other of the contacts.

2. An electric switch as claimed in claim 1,. wherein the opposite side has an arcuate shape.

3. An electric switch as claimed in claim 1, wherein the opposite side has two end portions and a portion intermediate the two end portions, wherein the end portions are inclined to the intermediate portion.

4. An electric switch as claimed in claim 1, wherein the fulcrum is defined by an edge of a strip of metal.

5. An electric switch as claimed in claim 1, wherein the actuator is linearly, reciprocable.

6. An electric switch as claimed in claim 1, and ( including a third electric contact on the side of the fulcrum opposite to the first electric contact and with which third electric contact the leading end of the contact bridging member is brought into engagement as a result of the aforesaid pivoting.

7. An electric switch as claimed in claim. 1, wherein the length of the contact bridging member is at least twice that of the spacing of adjacent ones of the contacts.

8. An electric switch as claimed in claim 1, wherein in moving along the path, the leading end of the contact bridging member engages a body member adapted to exert'a force thereon until the member pivots about the fulcrum.

9. An electric switch as claimed in claim 1, wherein the contacts lie in the same plane.

10. An electric switch as claimed in claim 1, wherein the contacts lie on an imaginary convexedly curved surface and the contact bridging member has a curvature greater than that of the surface. 435S5

11. A switch as claimed in claim 1, wherein the switch is a rotary switch.

12. An electric switch as claimed in claim 1, including another such switch mechanism. 5

13. An electric switch as claimed in claim 1, further including a second mechanism which is a replica of the first-described mechanism, but uses the same actuator, whereby both mechanisms may be simultaneously operated by the actuator. 10

14. An electric switch as claimed in claim 1 and including a cam and a cam follower operative in use to stabilize the member in predetermined positions.

15. An electric switch as claimed in claim 1, wherein a means applying force to the actuator is adapted to 15 conduct current to or from the member.

16. An electric switch substantially as herein described with reference to and as shown in the accompanying drawings.