GB1352714A - Electrical switch - Google Patents

Abstract

1352714 Snap-action switches; retractive switches ROBERT BOSCH GmbH 23 July 1971 [24 July 1970] 34560/71 Heading H1N A switch includes a key 25 which rotates a driver 27 which turns a movable contact 35 relative to fixed contacts 40, 41, 42, 43 (contact 43 being in Fig. 5, not shown), driver 27 and the housing 20 having opposed faces 31, 32 on one of which is a step dog 33 and on the other of which is a stop contour guide surface 34, Figs. 14 and 15. Compression spring 38 urges face 32 against face 31 and movable contact 35, which is a bridging contact, against fixed contacts 40, 41, 42, 43, which are arranged in a circle. In the embodiment described, stop dog 33 is on surface 32 of driver 27 which surface also carries an impact dog 70, and the contour surface 34 is on the housing. Two different surfaces 34 may be provided, that shown in Fig. 14 (snap-action from position A to position B and back again) or that shown in Fig. 15 (snap-action from position A<SP>1</SP> to position B<SP>1</SP>, then non-snap-action from position B<SP>1</SP> to position C<SP>1</SP>, and retraction from C<SP>1</SP> to B<SP>1</SP> when the key is released). Consider Fig. 14. Initially stop dog 33 is at A, impact dog 70 contacts limiting dog 68 to limit the travel of stop dog 33 and fixed contacts 40, 41 are bridged. When driver 27 is rotated, stop dog 33 rides on to protuberance 53 against the force of compression spring 38 until stop dog 33 rides over apex 54 of protuberance 53 and snaps into recess 55 under the action of spring 38. The stop dog 33 is then at B, impact dog 70 is against limiting dog 69, and fixed contacts 42, 43 are bridged. Stop dog 33 remains in this position until driver 27 is rotated back manually, snapping back to position A. Consider Fig. 15. Initially stop dog 33 is at A<SP>1</SP>, impact dog 70 contacts limiting dog 68, and fixed contacts 40, 41 are bridged. When driver 27 is rotated, stop dog 33 rides over apex 54 of protuberance 53 and snaps into recess 55. Stop dog 33 is then at B<SP>1</SP>, impact dog 70 is not in contact with either limiting dog 68 and 69, and the fixed contacts are open. If driver 27 is rotated further, stop dog 33 rides on to surface 72 until impact dog 70 strikes limiting dog 69. Stop dog 33 is then in position C<SP>1</SP>, and fixed contacts 42, 43 are bridged. However, when dog 33 moves from B<SP>1</SP> to C<SP>1</SP> a leaf spring 74, Fig. 6 (not shown) is stressed and when the key is released, spring 74 returns dog 33 from C<SP>1</SP> to B<SP>1</SP> where it remains unless moved manually by the key back to A<SP>1</SP>. Surface 34 may be a loose piece, interchangeable.