GB904712A - Improvements in or relating to automatic drives - Google Patents

Abstract

904,712. Change-speed and clutch control. WEYMANN, C. T. Jan. 30, 1959 [Jan. 31, 1958], No. 3469/59. Class 80 (2). In an electro-pneumatic change-speed control in a motor vehicle having a main clutch 52 disengaged by a servomotor 54 energized by inlet manifold depression through an electromagnetic valve 56, and wherein the cross-shift and gear establishing movements of at least one conventional gear shift lever 9 are respectively effected by servomotors energized by inlet manifold depression, the gear establishing servomotor 1 is double-acting and comprises a spring- centred piston 25 which is connected to the gear lever 9 through spring-centring lost-motion means 17 permitting movement of the piston 25 beyond the positions corresponding to the extreme positions of the lever 9 and carries two cams 21, 22 arranged to open contacts 23 in the circuit of the valve 56, the distance between the cams 21, 22 being such that switch 23 is opened only after gear establishment. The cams 21, 22 are also arranged to open contacts 24 which when closed effect throttle closure. Control is manual, Fig. 1, or combined manual and speed-accelerator-responsive automatic, Fig. 2, and automatic engine-speed and accelerator-responsive starting control of the clutch may be provided. In Fig. 1, the shift lever 9 of a three-forward speed and one reverse change-speed gear is actuated by eyelet members 31 and 18 respectively connected to the pistons 28, 25, respectively, of a cross-shifting single-acting servomotor 2 energized through a solenoid valve 5 and the gear establishing double-acting servomotor 1 energized through solenoid valves 3, 4, through spring centring lost-motion means 17<SP>1</SP>, 17 permitting movement of the servomotor pistons beyond the extreme positions of the lever 9. The valves 3, 4, 5 are controlled by a manual selector switch 8 through relays 6, 7 and through contacts 37, 38 closed by cams 35, 35<SP>1</SP>, 36, 36<SP>1</SP> on the piston 28 which contacts permit gear establishment movement only after any necessary cross-shift. In Fig. 2 the manual selector switch 8 has also a position A for automatic change-speed control through an output speed responsive centrifugal switch 40 described in Specification 738,471. The switch 40 has two speed ranges A1, A2 selected by a change-over switch 42 dependent upon accelerator pedal position. With the manual switch 8 on A the main clutch 52 is disengaged and the throttle closed, irrespective of the accelerator pedal position, automatically, when the piston of the servomotor 1 is removed from either terminal position, the control contacts 23, 24 and the lost-motion means 17 being so arranged that clutch reengagement and re-instatement of accelerator pedal throttle control are effected only after gear establishment. The main clutch 52 is actuated by a conventional pedal 53 or by the servomotor 54 energized by inlet manifold depression through engagement rate adjusting means 55, described in Specification 859,519, dependent on clutch and accelerator member positions and through a solenoid valve 56. The valve 56 is controlled by the contact 23 and by a centrifugal switch 57 also described in Specification 859,519, which latter switch opens for clutch re-engagement only on increasing engine speed and therefore provides also an automatic starting control. The switch 57 may be disconnected by opening a switch 64, or the valve 56 may be actuated by a manual switch 58. The said throttle closure is effected against a spring 49 by a solenoid 50 energized through the contact 24. The gear change may be selectively controlled by the switch 8, using the studs I, II, III and AR (for reverse) whilst the clutch is automatically controlled by closing a switch 59; the gear change may be manually operated whilst the clutch is automatically controlled by setting the switch 8 to 0 and closing the switch 59; or operation may be completely manual by opening a master switch 61 or by setting the switch 8 to 0 and keeping contacts 58 and 59 open. In Fig. 3 (not shown), the servomotor 2 is double-acting to effect cross-shift for four forward speeds and one reverse.