US3746803A - Electrical switch having two movable contacts operable by a rotor and having fixed contact posts - Google Patents

Abstract

An electrical switch has a base and a cover between which is mounted a rotor carrying a movable contact. On the base there are first and second contact posts, and in one position these posts are bridged by the movable contact. There is also a conductive bridging member movable to bridge the posts in response to movement of the rotor into said one position, this bridging member including a pair of limbs arranged to engage the first contact post in one angular position of the rotor, one of the limbs then moving into engagement with the second contact post when the rotor is moved into said one position. If the rotor is moved beyond said one angular position the limbs are urged against the contact posts so as to remain in bridging engagement therewith.

Description

United States Patent [191 Cryer ELECTRICAL SWITCH HAVING TWO MOVABLE CONTACTS OPERABLE BY A ROTOR AND HAVING FIXED CONTACT POSTS [75] Inventor: Edward Cryer, Higham, near Burnley, England [73] Assignee: Joseph Lucas (Industries) Limited,

Birmingham, England [22] Filed: Oct. 7, 1971 [21] Appl. No.: 187,272

[30] Foreign Application Priority Data Oct. 24, 1970 Great Britain 50,635/70 [52] [1.8. CI 200/6 R, ZOO/61.54, 200/166 BE, 200/166 J [5]] Int. Cl.....; H0lh 23/30, HOlh 2l/l8 [58] Field of Search 200/61.54, 166 SD, 200/l66 J, 153K, 6 R, 166 BE [56] References Cited UNlTED STATES PATENTS 3,629,524 l2/l97l Cryer ZOO/61.54X

[ July 17, 1973 Primary Examiner-Robert K. Schaefer Assistant Examiner-William J. Smith Attorney-Holman & Stern [57] ABSTRACT An electrical switch has a base and a cover between which is mounted a rotor carrying a movable contact. On the base there are first and second contact posts,

and in one position these posts are bridged by the mov- 4 Claims, 2 Drawing Figures I it 1516 25 ELECTRICAL SWITCH HAVING TWO MOVABLE .CONTACTS OPERABLE BY A ROTOR AND HAVING FIXED CONTACT POSTS This invention relates to electrical switches.

An electrical switch, according to the invention, comprises a base, a cover supported in spaced relationship with the base, a rotor mounted between the base and the cover for angular movement relative thereto, a movable contact carried by the rotor, first and second contact posts supported by the base, said contact posts being angularly spaced from one another and being bridged by said movable contact when said rotor is moved into a second angular position from a first angular position, and a conductive bridgingmember movable to bridge said first and second contact posts in response to movement of the rotor into said second angular position from said first angular position, said bridging member including a pair of limbs arranged so as to engage said first contact post in'said first angular position of the rotor, movement of the rotor from said first angular position into said secondangular position moving one of said limbs into engagement with said second contact post, the arrangementfurther being such that if said rotor is moved from said first angular position through said second angular position said limbs are urged against said first and second contact posts respectively so as to remain in bridging engagement therewith.

Preferably, the switch further includes a third contact post-positioned on the side of said first contact post remote from said second contact post and angularly spacedfrom said first contact post, said first and third contact posts being bridged by the movable contact in said firstangular position of the rotor, and said bridging member being movable in response to movement of the rotor to a further predetermined angular position to bridge said first and third contact posts.

Preferably, said limbs are formed of a resilient material and are arranged so as to be urged by theirown resilience into engagement with said first contact post in said first angular position ofthe rotor.

Preferably, the movable contact is a conductive spring-operated roller, said spring-operated roller providing detent means for retaining said rotor in said predetermined angularpositions thereof.

- In the accompanyingdrawings, which illustrate one example of the invention,

FIG. 1 is a sectional view of an electrical switch, and

FIG. 2 is a plan view of the switch shown in FIG. 1 with the cover removed.

' Referring to the drawings,1the switch includes a base 11 and a cover 12 supported in spaced relationship above the bascll. Mounted between the base 11 and the cover 12 is a moulded synthetic resin. rotor 13, the

rotor 13 being formed adjacent one end 14 thereof with an integral post 15 which extends through apertures in the base I l and the cover 12 respectively tojournal the rotor 13 for angular movement relative to the base and the cover. The rotor 13 includes a downwardly projecting peg 16 which extends into an arcuate slot in the conductive po'sts18, 19, 21 and 22. The posts 18, 19,

21 and 22 are positioned along an arc of a circle having its center on the rotational axis of the rotor 13 and each of the posts extends through the cover 12 to define a terminal of the switch. At itsend remote from the end 14, the rotor carries a conductive roller 23, the roller 23being urged by a spring 24 supported in a bore 25 in the rotor 13 into bridging engagement with adjacent pairsof conductive posts 18, 19, 21 and 22.

Mounted around the post 15 between the rotor 13 and the cover 12 is a conductive wire spring 26, the

spring 26 being shaped to define a pair of limbs 27,28'

extending from the post 15 towards the conductive posts 18, 19, 21 and 22. Intermediate their ends the limbs 27,28 cross one another so that the free ends of the limbs 27,28 are engaged with the conductive post 21 the resilience of the limbs 27,28 maintaining the limbs in contact with the post 21. Extending upwardly from the rotor 13 towards the cover 12 are a pair of integral fingers 29,31 which are positioned on opposite sides respectively of the rotor13 so that the limbs 27,28 of the spring 26 extend between the fingers 29,31. The arrangement of the switch is such that during angular movement of the rotor 13 relative to the base 11 the fingers 29, 31 can engage the limbs 27,28 respectively of the spring 26.

The conductive posts 18,19, 21 and 22 together with the spring urged roller 23 define three stable positions of the rotor 13 during angular movement of the rotor; In a first position of the rotor the roller 23 is engaged with the posts 18, 19 to complete a circuit therebetween and in second and third positions of the rotor 13 the roller 23 completes circuits between the posts 19, 21 and the posts 21,22 respectively. During movement of the rotor 13 between the first and second positions the spring 26 is stationary, and in these positions, since the limbs 27, 28 of the spring are engaged only with the contact post 21, the springdoes not complete any circuits within the switch. However, during movement of the rotor 13 from its second position to its third position the finger 31 engages the limb 28 of the spring and urges the limb 28 towards the contact post 22. Thus in the third position of the' rotor 13 the contact'posts 21,22 are bridged by the spring 26 as well as the roller 23'. It is to be appreciated that if, for example, owning to manufacturing tolerances, the permitted angular movement of the rotor 13 is suchasto allow further movement of the rotor from the third position away from the second position then this further movement of the rotor will tend to urge the roller 23 out of engagement with the contact post 21 so as to break the circuit between the contact posts 21,22. However, as will readily be appreciated from FIG. 2, by providing the spring 26 which under the action of the finger 31 is I moved into bridging engagement with the posts 21,22

in the third position of the switch, during any further gaged only with the contact post 18. During movement of the rotor 13 from its first position the finger 29 engages the limb 27 of the spring 26 so as to urge the limb 26 towards the contact post 19. Thus in the fourth position of the rotor the limb 27 is engaged with the contact post 19 so as to complete a circuit between the contact posts 19, 21. The rotor 13 is resiliently urged away from the third position towards the second position and upon release of the rotor 13 in the fourth position the rotor is moved under the resilience of the limb 27, and the action of the spring 25 back to the first position.

The switch described above is particularly designed for use in controlling operation of a self-parking, twospeed, permanent magnet windscreen wiper motor. The contact post 21 defines the feed terminal of the switch, whereas the posts 19, 22 are connected in the slow speed and fast speed circuits respectively on the wiper. Thus, in the second position of the rotor 13 the roller 23 bridges the posts 19, 21 to complete the slow speed circuit of the motor and in the third position the roller 23 bridges the posts 21,22 to complete the fast speed circuit of the motor. The contact post 18 is connected to the parking switch of the wiper motor to earth so that in the first positionof the rotor 13, when the windscreen wipers have completed a stroke, then the armature of the windscreen wiper motor is shortcircuited to achieve dynamic braking of the motor. Further, by moving the rotor 13 to its fourth position, the slow speed circuit of the motor is completed by the spring 26. Thus, if the rotor 13 is moved to its fourth position and then immediately released whereby the rotor returns to its first position the windscreen wiper motor can be caused to drive the wipers through one complete stroke. i

I claim:

1. An electrical switch comprising a base, a cover supported in spaced relationship with the base, a rotor, means mounting the rotor between the base and the cover for angular movement relative thereto between a first angular position and a second angular position a movable contact carried by the rotor, first and second contact posts supported by'the base, said contact posts being angularly spaced from one another and being bridged by said movable contact when the rotor is moved into said Second angular position from said first angular position, a conductive bridging member movable to bridge said first and second contact posts in response to movement of the rotor into said second angular position from said first angular position, said bridging member including a pair of limbs which engage said first contact post in said first angular position of the rotor, movement of the rotor from said first angular position into said second angular position movin'g one of said limbs into engagement with said second contact post, and abutment means carried by the rotor and engageable with said bridging member if said rotor is moved from said first angular position through said second angular position so as to urge said limbs against said first and second contact posts respectively so that the limbs remain in bridging engagement with the contact posts.

2. A switch as claimed in claim 1 further including a third contact post positioned on the side of said first contact post remote from said second contact post and angularly spaced from said first contact post, said first and third contact posts being bridged by the movable contact in said first angular position of the rotor, and said bridging member being movable in response to movement of the rotor to a further predetermined angular position to bridge said first and third contact posts.

3. A switch as claimed in claim 1 in which said limbs are formed of a resilient material and are arranged so as to be urged by their own resilience-into engagement with said first contact post in said first angularposition of the rotor.

4. A switch as claimed in claim 1 in which the movable contact is a conductive spring-operated roller, said spring-operated roller providing detent means for retaining said rotor in said predetermined angular positions thereof.

Claims (4)

1. An electrical switch comprising a base, a cover supported in spaced relationship with the base, a rotor, means mounting the rotor between the base and the cover for angular movement relative thereto between a first angular position and a second angular position , a movable contact carried by the rotor, first and second contact posts supported by the base, said contact posts being angularly spaced from one another and being bridged by said movable contact when the rotor is moved into said second angular position from said first angular position, a conductive bridging member movable to bridge said first and second contact posts in response to movement of the rotor into said second angular position from said first angular position, said bridging member including a pair of limbs which engage said first contact post in said first angular position of the rotor, movement of the rotor from said first angular position into said second angular position moving one of said limbs into engagement with said second contact post, and abutment means carried by the rotor and engageable with said bridging member if said rotor is moved from said first angular position through said second angular position so as to urge said limbs against said first and second contact posts respectively so that the limbs remain in bridging engagement with the contact posts.

2. A switch as claimed in claim 1 further including a third contact post positioned on the side of said first contact post remote from said second contact post and angularly spaced from said first contact post, said first and third contact posts being bridged by the movable contact in said first angular position of the rotor, and said bridging member being movable in response to movement of the rotor to a further predetermined angular position to bridge said first and third contact posts.

3. A switch as claimed in claim 1 in which said limbs are formed of a resilient material and are arranged so as to be urged by their own resilience into engagement with said first contact post in said first angular posiTion of the rotor.

4. A switch as claimed in claim 1 in which the movable contact is a conductive spring-operated roller, said spring-operated roller providing detent means for retaining said rotor in said predetermined angular positions thereof.

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