GB2070337A

GB2070337A - Electromagnetic switch

Info

Publication number: GB2070337A
Application number: GB8106065A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1980-02-27
Filing date: 1981-02-26
Publication date: 1981-09-03
Also published as: IT1135553B; DE3007349A1; GB2070337B; JPS56134436A; IT8119872A0; JPS6344259B2; FR2476932B1; FR2476932A1; DE3007349C2

Abstract

A plunger armature switch comprises a base plate (1) on which are disposed a magnet core (2), a yoke (6, 7), a winding (5) and a brass guide sleeve (3). A preassembled structural unit comprising the armature (9) and a movable contact bridge sub-assembly (16) is held in its normal position against an abutment member (32) against the force of a return spring (10) which abuts against the magnet core (2). The abutment member (32) is made from a tough resilient insulating material and is located transversely across the contact bridge (16) and is releasably secured by latch means (36 to 38) to a fastening plate 8 which is secured to the base (7) of the yoke and which carries the fixed electrical contacts (26; 27). The switch may be used as a control relay for a two-stage starter device for internal combustion engines. <IMAGE>

Description

SPECIFICATION Solenoid switch The invention relates to solenoid switches.

A solenoid switch in electrical two-stage starter devices is already known which has a contact bridge actuated by an armature and cooperating with fixed contacts. At least two metal members are bolted in an insulated manner to a fastening plate carrying the fixed contacts or to angled brackets carrying the fixed contacts and serve as abutment members for the contact bridge when in the normal or unenergised position. This switch has the disadvantage that, owing to the lack of space, the metal members are of complicated construction and are expensive to manufacture, and it is a complicated, and thus expensive, matter to secure them in a manner in which they are insulated from the current-carrying parts of the switch. This precludes economic mass production.

A solenoid switch in accordance with the invention, comprises a base plate to which are secured a yoke and a magnet core on which is mounted a sleeve carrying a winding carrier having a winding thereon, a fastening plate which carries fixed contacts and which is secured to the yoke, an armature movably disposed in the sleeve and having armature rod on which is movably disposed a contact bridge co-operating with the fixed contacts and a contact pressure spring acting on the contact bridge the armature, the armature rod, the contact bridge, a contact bridge carried therefor and the contact pressure spring forming a structural unit which is abutted at one side by a return spring in the sleeve and which abuts at the other side against an abutment member which is snap-fitted onto the fastening plate.

This has the advantage that a one-part abutment member can engage over the contact bridge and can releasably engage the fastening plate of the switch.

A further advantage is that the costs of material and assembly are substantially reduced by omitting all separate fastening means for the abutment member, and it is possible to change the parts in a simple manner.

It is particularly advantageous for the abutment member two be made from insulating plastics material so that it can be readily provided with a configuration adapted to the confined installation space, has high resistance to vibration and a high damping action, and does not require any additional insulating parts.

The invention is further described, by way of example, with reference to the drawings, in which Figure 1 is a cross sectional through a solenoid switch in accordance with the invention, Figure 2 is a side elevation of the switch, Figure 3 is a plan view of the switch, and Figure 4 is a cross section through a modification of the switch of Figure 1.

The electromagnetically actuated switch shown in the drawings is a control relay which controls the second stage of an electrical two-stage starter device for internal combustion engines. A two-stage starter device is one in which an engaging solenoid brings the starter pinion partially into mesh with the ring gear on the engine fly wheel before the starter motor is fully energised by the control relay. The control relay has a base plate 1 by which the control relay is secured to a starter motor (not illustrated). A brass sleeve 3 is rigidly disposed on a magnet core 2 which is mounted on the base plate 1. The brass sleeve 3 extends through a winding carrier 4 which carries a winding 5. A substantially U-shaped yoke 6 is also secured to the base plate 1.The brass sleeve 3 extends through the base 7 of the yoke 6 and through a fastening plate 8 which is rigidly disposed on the outside of the base 7. The magnet core 2, the yoke 6,7 and the fastening plate 8 are made from a magnetizable material. An armature 9 is movably guided in the brass sleeve 3. A return spring 10 retains the armature 9 in its normal position shown in Figure 1. The return spring 10 accommodated in the brass sleeve 3 abuts against an end face of the armature 9 and is supported in a guide bore 11 in the magnet core 2. An armature rod 12 is secured in a blind bore 13 in the other end of the armature 9.

A contact bridge carrier 14 has a support extension 15 on which a contact bridge 16 is mounted. An insulating ring 18 is fitted in an annular groove 17 in the end face of the support extension 15. One side of an insulating plate 19 abuts against the contact bridge 16 and the other side of the insulating plate abuts against a stop arm 20. The contact bridge carrier 14, the contact bridge 16, the insulating plate 19 and the stop arm 20 are interconnected by rivets 21 to form a contact bridge sub-assembly 14, 16, 19, 20. The contact bridge sub-assembly 14, 16, 19,20 is movably mounted on the armature rod 12 on which a contact pressure spring 22 is also disposed. One end of the contact pressure spring 22 abuts against the stop arm 20 and the other end of the contact pressure spring abuts against a stop 23 on the armature rod 12.The armature 9 and the contact bridge sub-assembly 14, 16, 19, 20 thus constitute a preassembled structural unit or module.

A respective contact 26 and 27 is mounted on each of two insulating plates 24 and 25 which are disposed on the fastening plate 8, the contacts 26 and 27 being riveted to the fastening plate 8 by rivets 29 with insulating washers 28 disposed therebetween. A bifurcated stop lever 31 is hinged to a pivot bearing 30 which is riveted to the fastening plate 8 in the region of the insulating plate 24.

During assembly, the preassembled structural unit comprising the armature and the contact bridge sub-assembly is pressed in the brass sleeve 3 towards the magnet core 2 against the force of the return spring 10. An abutment member 32 for the contact bridge sub-assembly has a central bore 33 in the region of which a recess 34 is formed in an abutment surface 35. Two limbs 36 of the abutment member 32 extend beyond the abutment surface 35, each of which limbs has an inwardly directed clamping projection 37 and a sneck 38 at the free end of the limb. The abutment member 32 is made from a tough, resilient insulating material and is slipped over the armature rod 12 during assembly. The abutment surface 35 of the abutment member presses against the insulating plate 19.The limbs 36 then engage the fastening plate 8 such that the clamping projections 37 press against the fastening plate 8, while the snecks 38 embrace the edge of the fastening plate 8. The movably arranged structural unit comprising the armature and the contact bridge sub-assembly is urged against the abutment surfaces 35 of the abutment member 32 by the return spring 10 and is thus held in its normal position. A fork end 39 of the stop lever 31 extends through a slot 40 in the stop arm 20.

When the starter switch (not shown) is closed, the relay winding 5 is energised as is the engaging solenoid (not shown) for the starter pinion. The contact pressure spring 22 presses the contact bridge 16 downwards but the latter is held away from the fixed contacts 29 by the engagement of the stop arm 20 with a shoulder on the stop lever 31.

When the engaging solenoid has brought the starter pinion almost fully into mesh, a trip arm on the armature of the engaging solenoid comes against the stop lever 31 and pivots the latter clockwise in Figure 2 to release the stop arm 20 and so enable the contact bridge 16 to be pressed by the spring 22 against the fixed contacts 29, thereby fuily energising the starter motor.

A modification of the solenoid switch is illustrated in Figure 4. The parts which are the same as those in the switch described above are provided with the same reference numerals.

In the preassembled structural unit 12 to 18, 20 comprising the armature and contact bridge subassembly, a narrow insulating plate 41, which projects only slightly beyond the width of the stop arm 20, is disposed between the end face 42 of the support extension 15 of the contact bridge carrier 14 and the stop arm 20. A recess 44 having a widened edge portion is incorporated in an abutment member 43 in the region of the central bore 33. When in the normal position, a projecting abutment surface 45 abuts directly against the contact bridge 16. and the insulating plate 41 extends into the edge portion of the recess 44. The modified abutment member 43 is otherwise identical to the abutment member 32.

Claims

1. A solenoid switch, comprising a base plate to which are secured a yoke and a magnet core on which is mounted a sleeve carrying a winding carrier having a winding thereon, a fastening plate which carries fixed contacts and which is secured to the yoke, an armature movably disposed in the sleeve and having armature rod on which is movably disposed a contact bridge co-operating with the fixed contacts and a contact pressure spring acting on the contact bridge the armature, the armature rod, the contact bridge, a contact bridge carrier therefor and the contact pressure spring forming a structural unit which is abutted at one side by a return spring in the sleeve and which abuts at the other side against an abutment member which is snap-fitted onto the fastening plate.

2. A switch as claimed in claim 1, in which the abutment member is made from a tough resilient insulating material.

3. A switch as claimed in claim 1 or 2, in which the contact bridge is arranged to abut directly against an abutment surface on the abutment member.

4. A switch as claimed in claim 1 or 2, in which a plate of insulating material is disposed on the armature rod between the contact bridge and the contact pressure spring and is arranged to abut against an abutment surface on the abutment member.

5. A switch as claimed in any of claims 1 to 4, in which the abutment member has a central bore through which extends that portion of the armature rod which carries the contact pressure spring.

6. A switch as claimed in any of claims 1 to 5, in which the abutment member extends transversely across the contact bridge.

7. A switch as claimed in any preceding claim, in which a stop arm is attached to the contact bridge and to the contact bridge carrier to form a subassembly which is part of said structural unit and in which a stop lever is pivoted to the fastening plate and cooperates with the stop arm to prevent the contact bridge from being pressed against the fixed contacts until the stop lever is stripped.

8. A solenoid switch as claimed in any preceding claim which is a control relay for a two-stage starter for an internal combustion engine.

9. A solenoid switch constructed and adapted to operate substantially as herein described with reference to and as illustrated in the drawings.