US3621159A

US3621159A - Ignition switch with blocking means

Info

Publication number: US3621159A
Application number: US9930A
Authority: US
Inventors: Alec John Heap
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1969-02-18
Filing date: 1970-02-10
Publication date: 1971-11-16
Anticipated expiration: 1988-11-16
Also published as: DE2007257A1; US3621157A; GB1290148A; FR2035620A5

Abstract

An electrical switch for use in road vehicles includes a casing carrying fixed contacts, and a rotor mounted for rotation in the casing of the rotor carrying a movable contact engageable with the fixed contacts to complete the circuits of the switch. The rotor has first and second stable positions with respect to the casing, and also has an unstable third position, the rotor being urged angularly from its third position back to its second position by a torsion spring. A cam form is provided on the casing, and a pawl is mounted on the rotor and is engageable with the cam form. The pawl is spring urged to either a first or second position relative to the rotor, and the arrangement of the pawl and the cam form on the casing is such that the pawl prevents movement of the rotor from its second position to its third position unless the previous movement of the rotor has been from its first position to its second position.

Description

United States Patent [72] Inventor Alec John Heap Burnley, England [21 1 Appl. No. 9,930

[22] Filed Feb. 10, 1970 [45] Patented Nov. 16, 1971 [73] Assignee Joseph Lucas (Industries) Limited Birmingham, England [32] Priority Feb. 18, 1969 [33 Great Britain [54] IGNITION SWITCH WITH BLOCKING MEANS 1 Claim, 5 Drawing Figs. [52] US. Cl 200/42 R, 200/44 [51 1 Int. Cl H01h 27/06 [50] Field oiSearch ..200/l53.24, 166 SD, 44, 42

[56] References Cited UNITED STATES PATENTS 3,172,968 3/1965 Arendt 200/44 FOREIGN PATENTS 1,131,465 6/1962 Germany 1,018,357 H1966 GreatBritain ZOO/44 200/ 166 SD ABSTRACT: An electrical switch for use in road vehicles includes a casing carrying fixed contacts, and a rotor mounted for rotation in the casing of the rotor carrying a movable contact engageable with the fixed contacts to complete the circuits of the switch. The rotor has first and second stable positions with respect to the casing, and also has an unstable third position. the rotor being urged angularly from its third position back to its second position by a torsion spring. A cam form is provided on the casing, and a pawl is mounted on the rotor and is engageable with the cam form. The pawl is spring urged to either a first or second position relative to the rotor, and the arrangement of the pawl and the cam form on the casing is such that the pawl prevents movement of the rotor from its second position to its third position unless the previous movement of the rotor has been from its first position to its second position.

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INVENTOR ATT6FQNEYS IGNITION SWITCH WITH BLOCKING MEANS This invention relates to electrical switches for usein road vehicles.

An electrical switch according to the invention includes a casing carrying fixed contacts, a rotor carrying movable contacts engageable with said fixed contact to complete circuits through the switch, the rotor being mounted for rotation in the casing from a stable first position to a stable second position and for rotation from said stable second position to an unstable third position, resilient means urging said rotor from said third position to said second position, and means preventing rotation of the rotor to said third position from said second position unless the previous movement of the rotor has been from said first position to said second position, characterized in that, said means comprises a cam form on the casing, a pawl engageable with the cam form and mounted on the rotor for angular movement relative thereto between a first position in which the pawl and the cam form cooperate to prevent movement of the rotor from its second position to its third position and a second position in which the pawl and the cam form do not prevent movement of the rotor from its second position to its third position, and further resilient means urging the pawl to either of its first and second positions with respect to the rotor, the arrangement being such that during movement of the rotor from its second position to its third position the pawl and the cam form cooperate to move the pawl to an intermediate position from which it is moved to its first position by said further resilient means when the rotor is moved from its third position to its second position, while during movement of the rotor from its second position to its first position said pawl and the cam form cooperate to cause the pawl to be moved to its second position.

One example of the invention is illustrated in the accompanying drawings wherein:

FIG. 1 is a sectional view of an ignition switch in a first position,

FIGS. 2, 3 and 4 are views similar to FIG. 1 showing the switch in three other positions, and

FIG. 5 is a sectional view of the switch in a plane at right angles to the plane of the section in FIG. I.

Referring to the drawings, the ignition switch includes a casing 11 housing a rotor II. The rotor 12 is mounted for rotation within the casing, and carries movable contacts 12a which cooperate with a plurality of angularly spaced fixed contacts 21 carried by a base 20 closing one end of the casing 11. The rotor includes an integral spigot 13 which extends into a sleeve integral with the casing 11, and the barrel of a cylinder lock is coupled to the spigot I3 so that rotation of the barrel of the cylinder lock by means of an operating key causes corresponding rotation 7 of the rotor 13 relative to the casing 11 and the fixed contacts 21. The rotor 12 has three operating positions with respect to the casing 11, a first position which is an off position wherein none of the circuits of the ignition switch are completed, a second position which is an ignition position, wherein the ignition circuit, of the vehicle in which the ignition switch is utilized, is completed through the ignition switch, and a third position which is a start position wherein both the ignition circuit and the starter motor circuit of the vehicle are completed through the ignition switch. Detent means (not shown) are provided for locating the rotor in either of its first or second positions with respect to the casing, and a torsion spring 23 is provided for urging the rotor from its third position back to its second position.

Integral with the rotor 13, and upstanding therefrom parallel with the axis of rotation of the rotor 13 is a post 14 upon which is pivotally mounted a pawl 15. The pawl 15 is generally triangular, with its apex generally presented towards the axis of rotation of the rotor, and its base presented towards the inner wall of the casing 11. Adjacent the pawl 15 the inner wall of the casing 11 is provided with a cam form including a radially inwardly directed projection 16 and a radial outwardly extending depression 17. Secured to the rotor 12 is a resilient leaf spring 18 which is engaged, intermediate its ends,

with the apex of the pawl 15. .The central region of the spring I8 is bent to define a portion which extends towards the pawl I5, and the arrangement is such that when the apex of the pawl I5 engages the projection of the spring 18, then the spring I8 is stressed. Thus, the spring 18 urges the pawl 15 to either of a pair of positions, wherein the projection of the spring 18 engages one or other of the sides of the pawl. One extremity of the pawl 15 adjacent the inner surface of the casing 11 is provided with an integral lug 15a which extends from the base of the pawl I5 towards the inner wall of the casing I I.

The operation of the switch is as follows, when the switch is in its first position (FIG. I) the pawl I5 will be in its second position with the lug 15a, thereof adjacent the face of the projection 16 remote from the depression 17. The lug 15a is spaced radially inwardly from the projection 16, and so counterclockwise rotation of the rotor 12 from its first position to its second position (FIG. 2) moves the lug 15a past the projection 16. However, in the second position of the pawl 15, the base of the pawl 15 engages the projection 16 when the rotor reaches its second position. Further anticlockwise rotation of the rotor 12 relative to the casing l 1 moves the rotor from its second position to its third position (FIG. 3), and during such further movement, the pawl 15 is moved by virtue of engagement of the base of the pawl with the projection I6, about the post 14, against the action of the spring I8. When the pawl 15 has moved angularly about the post I4 through sufficient distance to cause the apex of the pawl 15 to ride past the projection on the spring 18, then the spring 18 no longer resists the movement of the pawl 15, but urges the pawl 15 to rotate about the post 14 in the same direction. Thus in the third position of the rotor, the pawl 15 is urged by the spring 18 to an intermediate position wherein the lug 15a engages the inner surface of the casing lll.

As previously stated, the rotor 12 is urged by the torsion spring 23 from its third position to its second position, and so upon releasing the operating key of the ignition switch when the rotor is in the third position, the rotor is moved back to its second position. As the rotor 12 reaches its second position from its third position, the lug 15a is aligned with the depression 17, and so under the influence of the spring 18 the pawl 15 is moved angularly about the post 14 to the first position of the pawl, wherein the lug 15a enters the depression 17. In the first position of the pawl, one side of the pawl engages an abutment l9 integral with the rotor 12, the abutment I9 preventing rotation of the pawl about the post 14 beyond the second position. The parts of the switch are now in the positions shown in FIG. 4, and should an attempt be made to rotate the rotor 12 from its second position back to its third position then such movement of the rotor will be prevented by the engagement of the lug 15a in the depression 17, and the engagement of said side of the pawl with the abutment 19.

In order to move the rotor once again to its third position,

i the rotor must first be moved from its second position back to its first position. Clockwise rotation of the rotor 12 from its second position back to its first position engages the lug 15a with the projection 16, so that the pawl 15 is moved angularly about the post 14 from its first position back to its second position. Thus after moving the rotor from its first position to its second position the parts of the switch will, be in the positions shown in FIG. I, so that the above sequence of operations is repeated upon actuation of the switch.

It will be appreciated that it is impossible for the driver of a road vehicle utilizing a switch constructed as described above to energize the starter motor circuit of the vehicle by moving the rotor of the switch to its third position while the engine of the vehicle is running, provided that the engine of the vehicle has been started by operation of the switch, since the rotor of the switch must be returned to its first position, wherein the ignition circuit of the vehicle will be broken, before the rotor can be moved to its third position.

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

11. An electrical switch for a road vehicle, including a casing carrying fixed contacts, a rotor carrying movable contacts engageable with said fixed contact to complete circuits through the switch, the rotor being mounted for rotation in the casing from a stable first position to a stable second position and for rotation from said stable second position to an unstable third position, resilient means urging said rotor from said third position to said second position, and means preventing rotation of the rotor to said third position from said second position unless the previous movement of the rotor has been from said first position to said second position, characterized in that, said means comprises a cam form on the casing, a pawl engageable with the cam form and mounted on the rotor for angular movement relative thereto between a first position in which the pawl and the cam form cooperate to prevent movemerit of the rotor from its second position to its third position and a second position in which the pawl and the cam form do not prevent movement of the rotor from its second position to its third position, and further resilient means urging the pawl to either of its first and second positions with respect to the retor, the arrangement being such that during movement of the rotor from its second position to its third position the pawl and the cam form cooperate to move the pawl to an intermediate position from which it is moved to its first position by said further resilient means when the rotor is moved from its third position to its second position, while during movement of the rotor from its second position to its first position said pawl and the cam form cooperate to cause the pawl to be moved to its second position.

Claims

1. An electrical switch for a road vehicle, including a casing carrying fixed contacts, a rotor carrying movable contacts engageable with said fixed contact to complete circuits through the switch, the rotor being mounted for rotation in the casing from a stable first position to a stable second position and for rotation from said stable second position to an unstable third position, resilient means urging said rotor from said third position to said second position, and means preventing rotation of the rotor to said third position from said second position unless the previous movement of the rotor has been from said first position to said second position, characterized in that, said means comprises a cam form on the casing, a pawl engageable with the cam form and mounted on the rotor for angular movement relative thereto between a first position in which the pawl and the cam form cooperate to prevent movement of the rotor from its second position to its third position and a second position in which the pawl and the cam form do not prevent movement of the rotor from its second position to its third position, and further resilient means urging the pawl to either of its first and second positions with respect to the rotor, the arrangement being such that during movement of the rotor from its second position to its third position the pawl and the cam form cooperate to move the pawl to an intermediate position from which it is moved to its first position by said further resilient means when the rotor is moved from its third position to its second position, while during movement of the rotor from its second position to its first position said pawl and the cam form cooperate to cause the pawl to be moved to its second position.