GB995788A - Improvements in or relating to shift devices for change-speed gearboxes of motor vehicles - Google Patents

Abstract

995,788. Change-speed control. ZENTRALE ENTWICKLUNG UND KONSTRUKTION FUR DEN KRAFTFAHRZEUGBAU VEB. Jan. 15, 1963, No.1819/63. Heading F2D. An electro-fluid-pressure control for a motor vehicle change-speed gear comprises a spring- centred double-acting gear-selecting servo-motor 10, Fig. 2, and a double-acting ratio establishing servo-motor 27, Fig. 1, the former being controlled by electromagnetically operated valves 12, 13 in response to selective closing of manually operable switches 65, 66 in conjunction with a switch 56 closed when a main clutch is disengaged, whilst the latter 27 is controlled by electromagnetically operated valves 28, 29 in response to selective closing of manually operable switches 63, 64 in conjunction with a switch 21 closed when a shift finger 1 is moved from its central position or with a manually operable switch 60. All the electromagnetically operated valves are de-energized and the servomotors relieved of pressure when a ratio shift is completed. The main clutch is disengaged by a fluid-pressure servomotor 48 controlled by an electromagnetically operated valve 50 in response to closing a manually operated switch 61 or 62, the former switch disengaging the clutch prior to selection and establishment of a ratio whilst the latter switch disengages the clutch prior to neutralizing the gear which is effected by a servomotor 40 controlled by an electromagnetically operated valve 43. The switches 60... 66 may be operated by a control roller having a series of switch operating projections thereon and the roller may be rotated by a hand lever or by an electromagnetically actuated ratchet mechanism. Operation.-As shown, all the electric circuits are open and the gear neutralized. To engage first ratio the switches 61, 64 and 66 are closed, the former 61 of which completes a circuit through a switch 39, which is closed when the gear is neutralized, to the clutch valve 50. The clutch servomotor 48 disengages the clutch and closes a switch 56 which completes a circuit through the switch 66 to the valve 13. Fluid pressure is thus supplied to the right-hand side of the servomotor 10 to move left the shift finger 1, which is axially slidable on a rod 2, whereupon a ball 16 rides out of a groove in the finger 1 and acts through a rod 20 to close the switch 21 and complete the circuit through the switch 64 to the valve 29. Fluid pressure is thus supplied to the right-hand side of the servomotor 27 and moves left a rod 23 which acts through a lever 22 to turn the rod 2 and shift finger 1 to establish the gear ratio. The movement of the rod 23 opens the switch 39 and closes a switch 37, the former breaking the circuit to the clutch valve 50 whereupon the clutch is re-engaged and the switch 56 opened to de-energize the valves 13, 29 and relieve the servomotors 10, 27 of pressure fluid. Closure of the switch 37 energizes a delay 68 which closes its contacts a, b, c. To neutralize the gear prior to establishment of a new ratio the switch 62 is closed. A relay 67 is thus energized and closes normally open contacts a, b, c whilst opening a normally closed contact d. The closed contacts a, b, c of relays 67, 68 respectively hold the relay 67 energized, energize the clutch release valve 50, and energize the valve 43 which supplies pressure fluid to the neutralizing servomotor 40. The rod 23 is thus moved to the position shown and springs 16, 17 move the rod 2 to the position shown. The switch 39 is reclosed and the switch 37 reopened deenergizing the relay 68 which in turn de-energizes the clutch and neutralizing valves 50, 43. The other gear ratios are similarly established by selectively closing the switches 60 ... 66 in the combinations indicated in Fig. 3 (not shown).