US3816678A - Ignition switches - Google Patents

Abstract

An ignition switch for use in combination with a key operated steering column lock for a road vehicle including a casing, having a base at one end thereof, a plurality of fixed contacts are mounted on the base, and a rotor is rotatable within the casing. A movable contact plate is rotatable relative to the base, with said rotor, and movable contacts on the movable contact plate are engageable with certain of the fixed contacts on the base in predetermined angular positions of the rotor relative to the casing, so as to complete electrical circuits between said certain fixed contacts. The movable contact plate is urged towards the base so that the movable contacts engage the base, and cooperating cam means are provided on the contact plate and the casing so as to move at least part of the movable contact plate away from the base to prevent completion of electrical circuits between certain of the fixed contacts, which, in the absence of said cam means would be completed by said movable contact plate in said angular positions of the rotor. The cam means serves to move at least part of the movable contact plate away from the base by flexing or tilting the contact plate, the contact plate being radially split to facilitate flexure thereof.

Description

United States Patent [191 Thornley June 11, 1974 IGNITION SWITCHES [75] Inventor: Derek Thornley, Nelson, England [73] Assignee: Joseph Lucas (Industries) Limited,

Birmingham, England [22] Filed: Sept. 30, 1969 211 Appl. No.: 862,316

Primary ExaminerHerman J. Hohauser Attorney, Agent, or Firm-Holman and Stern [57] ABSTRACT An ignition switch for use in combination with a key operated steering column lock for a road vehicle including a casing, having a base at one end thereof, a plurality of fixed contacts are mounted on the base, and a rotor is rotatable within the casing. A movable contact plate is rotatable relative to the base, with said rotor, and movable contacts on the movable contact plate are engageable with certain of the fixed contacts on the base in predetermined angular positions of the rotor relative to the casing, so as to complete electrical circuits between said certain fixed contacts. The movable contact plate is urged towards the base so that the movable contacts engage the base, and cooperating cam means are provided on the contact plate and the casing so as to move at least part of the movable contact plate away from the base to prevent completion of electrical circuits between certain of the fixed contacts, which, in the absence of said cam means would be completed by said movable contact plate in said angular positions of the rotor. The cam means serves to move at least part of the movable contact plate away from the base by flexing or tilting the contact plate, the contact plate being radially split to facilitate flexure thereof.

3 Claims, 4 Drawing Figures PATENTEDJIIH I 1 m 38 163378 SHEET 10F '2 IGNITION SWITCHES This invention relates to ignition switches, for use in combination with key operated steering column locks for road vehicles, of the kind comprising a casing including a base at one end thereof, a plurality of fixed contacts on the base, a rotor rotatable within the casing, a movable contact plate rotatable relative to said base with said rotor, and movable contacts on said movable contact plate, said movable contacts being engageable with certain of said fixed contacts in predetermined angular positions of said rotor to complete electrical circuits between said certain fixed contacts.

According to the invention, in an ignition switch of the kind specified, said movable contact plate is urged towards the base so that said movable contacts engage the base, and co-operating cam means are provided on the contact plate and the casing, said cam means being operable in certain angular positions of the rotor to move at least part of the movable contact plate away from the base to prevent completion of electrical circuits between certain of said fixed contacts which, in the absence of said cam means, would be completed by said movable contact plate in said angular positions of the rotor.

One example of the invention will now be described with reference to the accompanying drawings, wherein:

FIG. 1 is a sectional view of an ignition switch, FIG. 2 is a sectional view on the line 2-2 in FIG. 1,

FIG. 3 is a diagrammatic representation of the operating positions of the switch, and

FIG. 4 is a side elevational view of the movable contact plate of the switch shown in FIG. 1.

Referring to the drawings, the ignition switch includes a hollow, cylindrical, die cast casing 11 which is partially closed at one end by an integral inwardly directed peripheral flange 12, and which includes, at its other end, a base constituted by an insulating contact block 13. Journalled in the peripheral flange 12 at one end of the casing, and in the contact block 13 at the other end of the casing, for rotation within the casing is a moulded rotor 14, which includes a cylindrical spigot 15 extending through the central hole in the flange 12, a main portion 16 within the casing adjacent the peripheral flange, and a non-circular spigot 17 which extends towards the contact block 13. The spigot 15 extends through the flange 12 and is provided with a non-circular bore, which in use receives a noncircular shaft coupled to the rotatable core of a key operated steeringcolumn lock, and through which the rotor is driven by the core of the lock.

Mounted on the spigot 17 of the rotor, for rotation therewith, is a conductive plate 21. The plate 21 is movable axially relative to the rotor, and includes four projections 22, 23, 24, 25 respectively which extend towards the block 13. The face of the plate 21 remote from the block 13 includes four depressions corresponding to the projections 22, 23, 24 and 25 and indicated by the suffix a in the drawings. Located in the depressions, and extending between the plate 11 and the main portion of the rotor are four helical compressing springs, the compression springs urging the plate21 towards the block 13, so that the projections 22, 23, 24, 25 engage the block 13. The plate 21 is generally rectangular, having the projections 22, 23, 24, 25 at the four corners thereof. The corners of the plate 21 adjacent the projections 22, 24 are provided with integral, outwardly extending cam followers 26, 27, and the plate 21 is provided, between the projections 22, 23 with a split 28 which extends from the periphery of the plate 21 to the central hole in the plate 21, and which renders the plate flexible.

The plate 21 constitutes the movable contact plate of the ignition switch, the projections 22, 23, 24, 25 being the movable contacts. The insulating contact block 13 carries five angularly spaced fixed contacts 29, 31, 32, 33, and 34 respectively (FIG. 3). The fixed contacts 29, 31, 32, 33 and 34 lie on the imaginary circle described by the movable contacts 22, 23, 24, 25 when the rotor of the switch is rotated through 360, and the contacts 29, 31, 32 and 34 are arcuate for reasons which will become apparent.

The cam followers 26, 27 of the plate 21 engage a peripheral cam track 30 formed on the contact board of the switch, and the arrangement is such that as the rotor is rotated the cam followers 26, 27 follow the profile of the cam track.

As previously stated the ignition switch is intended to be combined with a steering column lock for a road vehicle, and it is desired that the ignition switch should control the following electrical circuits of the vehicle, the hazard warning lamp circuit, the ignition circuit an accessory circuit, and the starter motor circuit of the vehicle. In order that the switch can be used with a steering column lock there must be sufficient spacing between the operative positions of the switch to permit the mechanical operation of the steering column lock, and with a conventional ignition switch, there would not be sufficient room to provide the necessary spacing between the number of contacts required to cope with the above operations of the switch.

The operation of the switch is as follows, the fixed contact 29 is connected in the ignition circuit of the road vehicle, the fixed contact 31 is the supply terminal of the ignition switch, the fixed contact 32 is connected in the accessories circuit of the road vehicle, the fixed contact 33 is connected in the starter motor circuit of the vehicle, and the fixed contact 34 is connected in the hazard warning light circuit of the vehicle. The contact plate 21, and the contacts 22, 23, 24, 25 serve to make the necessary electrical connections between the fixed contacts in the appropriate angular positions of the rotor. Detent means are provided between the rotor and the casing of the switch, to define the angular position of the rotor. In the first position of the switch (FIG. 3A) the steering column of the road vehicle is locked by the steering column lock, and only the hazard warning light circuit of the vehicle is completed. The cam followers 26, 27 are engaged in depressions in the cam track 30, and the contacts 22, 23 of the contact plate 21 are engaged with the fixed contact 31 while the contact 25 is engaged with the fixed contact 34 and the contact 24 is engaged with the insulating block 13. The fixed contact 31 is of sufiicient arcuate length to permit both the contacts 22 and 23 to engage the contact 31 simultaneously, and since the plate 21 is bridging the contact 31 and the contact 34 then the hazard warning lamp circuit of the vehicle is completed, it being appreciated that a manually operable control switch is provided in the hazard warning circuit to control operation of the hazard warning system. The second position of the switch (FIG. 3B) is a position wherein the hazard warning circuit of the vehicle is broken, but the accessories circuit of the vehicle is completed while the steering column is unlocked, and is reached by rotating the rotor of the switch through 60 in a clockwise direction from the first position. It will be recalled that the rotor 14 of the switch is driven by the core of the key operable steering column lock, and the additional 60 clockwise rotation from the second position is sufficient to release the steering column lock. In the second position of the switch, the cam follower 26 is still engaged in a depression of the cam track 30, but the cam follower 27 is engaged with a raised portion of the cam track 30 and so the plate 21 is tilted, the contacts 24, 25 being lifted away from the contact block 13. The plate 21 is thus positioned with the contact 22 engaged with the fixed contact 32, and the contact 23 engaged with the fixed contact 31 so that the accessories circuit of the vehicle is completed. The contact 24 is positioned axially in line with the fixed contact 29, but since the plate 21 is tilted the contact 24 does not engage the contact 29.

The third position of the switch (FIG. 3C) is a position wherein all of the electrical circuits of the vehicle are controlled by the switch, are broken, with the steering column unlocked. In order to reach the third position the rotor of the switch is turned through 30 in a clockwise direction from the second position. In the third position of the switch none of the movable contacts are engaged with the contact 31 and so no direct circuit can be made to the contacts 29, 32, 33 or 34. However in some circumstances it is possible for sneak circuits to be made between the contacts 29, 32, 33 and 34, and so in the third position of the switch both of the cam followers are engaged with projections on the cam track 30, so that the contacts 22 and 24 which are axially aligned with the fixed contacts 33 and 29 respectively, and the contact 25 are lifted away from the contact block 13. The contact 23 is urged by its respective compression spring into engagement with the fixed contact 32, the plate 21 flexing to allow the contact 23 to engage the fixed contact 32 as permitted by the split 28. However, since only the contact 32 is electrically connected to the plate 21, then no sneak circuits can be completed. The fourth position of the switch (FIG. 3D) is a position whereinthe steering column is unlocked, and the ignition, and accessory circuits of the vehicle are completed. In order to achieve the fourth position the rotor of the switch is rotated through 30 in a clockwise direction from the third position. In the fourth position, the cam follower 27 is engaged in a depression in the cam track 30, while the cam follower 26 is engaged with a raised projection on the cam track 30. The movement of the rotor 14 to the fourth position, moves the contact plate 21 so that the contact 25 is engaged with the fixed contact 29, the contact 24 is engaged with the fixed contact 31 and the contact 23 is engaged with the fixed contact 32, the contact 22 is positioned in axial alignment with the contact 34, but since the cam follower 26 is on a projection of the cam track 30 the contact 22 is lifted away from the fixed contact 34, the plate 21 being flexed as permitted by the split 28 to permit the contact 22 to be lifted away from the contact block while the contacts 23, 24, 25 engage their respective fixed contacts. Thus the plate 21 completes the electrical circuits between the supply contact 31 and the ignition and accessory contacts 29, 32 respectively, but does not complete the circuit to the hazard warning light contact 34 since the contact 22 is lifted clear of the contact 34.

The fifth position of the switch (FIG. 3B) is the start position of the switch wherein the ignition, and starter motor circuits of the vehicle are completed, but wherein the hazard warning, and accessory circuits are broken. The fifth position of the switch is achieved by rotating the rotor of the switch through 30 from the fourth position. In the fifth position the cam follower 27 is still engaged in the depression in the cam track 30, and the cam follower 26 is still engaged with the raised projection on the cam track 30, the contact 24 is still engaged with the fixed contact 31 and the contact 25 is still engaged with the fixed contact 29. The contact 22 is still axially aligned with the contact 34, and is still axially spaced from the contact 34 by virtue of the action of the cam follower 26 on'the cam track 30. However, the movement of the plate 21 has disengaged the contact 23 from the fixed contact 32 and has moved the contact 23 into engagement with the fixed contact 33. Thus, the ignition, and starter motor circuits of the vehicle are energised.

The detent means acting between the rotor and the casing does not restrain the rotor in its fifth position, and moreover the rotor is spring urged from its fifth position in an anti-clockwise direction towards its fourth position..Thus, when the force tending to turn the rotor to its fifth position is released the rotor and consequently the contact plate 21 are returned to the fourth position of the switch wherein the starter motor circuit of the vehicle is broken, and the ignition and accessory circuits of the vehicle are completed. Moreover, the switch includes latch means which, when the switch has been moved from its fourthto its fifth position and then has been returned to its fourth position, prevents the switch being moved immediately again to its fifth position, without first being returned to its third position. The latch means acts as a safety measure to prevent the starter motor circuit being energised while the engine is running.

Where the switch is to be used in a road vehicle equipped with an alternator, then the contact block carries, in addition to the fixed contacts 29, 31, 32, 33 and 34, a further pair of fixed contacts 35, 36 which are disposed within the imaginary circle defined by the path of movement of the contacts 22, 23, 24, 25, and which are connected in the field winding circuit of the alternator. The non-circular spigot 17 of the rotor 14 carries a bridging piece 37, which, in the fourth position of the switch bridges the contacts 35,36 and so completes the circuit to the field winding of the alterna tor to energise the field winding.

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

1. An electrical switch comprising a casing, a base at one end of the casing, a plurality of fixed contacts on the base, a rotor rotatable within the casing, a movable contact plate rotatable relative to said base with said rotor, movable contacts on said movable contact plate,

the base, and co-operating cam means on the contact plate and the casing, said cam means being operable in certain angular positions of the rotor to move at least part of the movable contact plate away from the base, against the action of said resilient means, to prevent completion of electrical circuits between certain of said fixed contacts, which, in the absence of said cam means, would be completed by said movable contact plate in said angular positions of the rotor, wherein said cam means causes tilting of the movable contact plate relative to the base, said tilting of the movable contact plate moving said part of the contact plate away from the base.

2. An electrical switch comprising a casing, a base at one end of the casing, a plurality of fixed contacts on the base, a rotor rotatable within the casing, a movable contact plate rotatable relative to said base with said rotor, movable contacts on said movable contact plate, said movable contact being engagable with said fixed contacts in predetermined annular positions of said rotor, to complete electrical circuits between said fixed contacts, detent means acting between the rotor and the casing to define predetermined stable positions of the rotor and the movable contacts relative to the casing, resilient means urging the movable contact plate towards the base, so that the movable contacts engage the base, and co-operating cam means on the contact plate and the casing, said cam means being operable in certain angular positions of the rotor to move at least part of the movable contact plate away from the base, against the action of said resilient means, to prevent completion of electrical circuits between certain of said fixed contacts, which, in the absence of said cam means, would be completed by said movable contact plate in said angular positions of the rotor, wherein said cam means causes flexure of the movable contact plate, said flexure of the contact plate moving said part of the contact plate away from the base.

3. The switch as claimed in claim 2 wherein said movable contact plate is annular and is formed with a split extending between the outer and inner peripheral edges of the plate, said split facilitating flexure of the plate.

Claims (3)

1. An electrical switch comprising a casing, a base at one end of the casing, a plurality of fixed contacts on the base, a rotor rotatable within the casing, a movable contact plate rotatable relative to said base with said rotor, movable contacts on said movable contact plate, said movable contact being engagable with said fixed contacts in predetermined angular positions of said rotor, to complete electrical circuits between said fixed contacts, detent means acting between the rotor and the casing to define predetermined stable positions of the rotor and the movable contacts relative to the casing, resilient means urging the movable contact plate towards the base, so that the movable contacts engage the base, and co-operating cam means on the contact plate and the casing, said cam means being operable in certain angular positions of tHe rotor to move at least part of the movable contact plate away from the base, against the action of said resilient means, to prevent completion of electrical circuits between certain of said fixed contacts, which, in the absence of said cam means, would be completed by said movable contact plate in said angular positions of the rotor, wherein said cam means causes tilting of the movable contact plate relative to the base, said tilting of the movable contact plate moving said part of the contact plate away from the base.

2. An electrical switch comprising a casing, a base at one end of the casing, a plurality of fixed contacts on the base, a rotor rotatable within the casing, a movable contact plate rotatable relative to said base with said rotor, movable contacts on said movable contact plate, said movable contact being engagable with said fixed contacts in predetermined annular positions of said rotor, to complete electrical circuits between said fixed contacts, detent means acting between the rotor and the casing to define predetermined stable positions of the rotor and the movable contacts relative to the casing, resilient means urging the movable contact plate towards the base, so that the movable contacts engage the base, and co-operating cam means on the contact plate and the casing, said cam means being operable in certain angular positions of the rotor to move at least part of the movable contact plate away from the base, against the action of said resilient means, to prevent completion of electrical circuits between certain of said fixed contacts, which, in the absence of said cam means, would be completed by said movable contact plate in said angular positions of the rotor, wherein said cam means causes flexure of the movable contact plate, said flexure of the contact plate moving said part of the contact plate away from the base.

3. The switch as claimed in claim 2 wherein said movable contact plate is annular and is formed with a split extending between the outer and inner peripheral edges of the plate, said split facilitating flexure of the plate.

Images