GB685783A - Improvements in ignition timing devices - Google Patents

Abstract

685,783. Interrupters. ETABLISSEMENTS DUCELLIER. May 8,1950 [May 16, 1949; May 2, 1950], No. 11459/50. Class 38 (v) [Also in Group XXVII] In an ignition. timing devise comprising a link 6 pivotally mounted on a base plate 4, a spring- loaded movable contactstud arm 8 pivotally mounted upon the link 6, a fixed contact-stud 15 mounted upon the base plate 4, and an interrupter actuating-cam 3 in operative contact with a follower 9 mounted on the arm 8, there is provided a member, such as rod 13, secured at one end to means responsive to induction-pipe pressure, for example a diaphragm, and at the other end to the link 6 so that during engine operation the diaphragm controls the position of the link 6 and hence the arm 8 whereby the angular position of the follower 9 is varied in accordance with induction-pipe pressure. The plate 4 carries a fixed pin 5 upon which is pivoted the link 6, the latter incorporating a stud 7 upon which is journalled the arm 8; the end of the link 6 remote from the pin 5 is pivotally connected to the rod 13 of the diaphragm, piston or capsule acted upon by the depression in the induction pipe. The fixed contact 15. has a rounded surface and a considerably larger area than contact 14 on arm 8 in order to permit freedom of movement of the latter during adjustment of the timing and the maintenance of a relatively constant contact gap. The distances between the axis of pin 5 and the centre of curvature of the fixed contact 15 and between the axis of stud 7 and the movable contact 14, and between the radius of curvature of the fixed contact 15 and the distance between the axis of pin 5 and stud 7 are equal so that the follower 9 is displaced curvilinearly upon movement of rod 13. Where the angular adjustment is small the surface of contact 15 may be flat. In a modification, the spring 11 which loads the arm 8 acts as an electrical conductor and is carried by the casing instead of the link; moreover the positions of pin 5 and stud 7 are interchanged whilst the rod 13 is housed at each end in a solid boss instead of being pivoted at these points. The timing adjustment effected by the device is additional to that made by the usual centrifugal means (not shown).