Patent GB-895826-A (GB)
Title: Improvements in or relating to clutch control systems for vehicles
Inventor: BLAND ALBERT NORMAN
IPC: F16D48/02
Filed: 1959-12-02
Abstract: 895,826. Controlling clutches. AUTOMOTIVE PRODUCTS CO. Ltd. Dec. 1, 1960 [Dec. 2, 1959], No. 41000/69. Class 80 (2). The main clutch of a motor car is disengaged by a fluid pressure operated servomotor either directly or indirectly, one valve in the supply system to the servomotor being sensitive to the speed of the car engine and a second valve controlled by changed in the car speed isolating the servomotor from the engine speed sensitive valve when the car speed exceeds a predetermined value. Partial disengagement of the clutch with consequential slipping when the car is in high gear but travelling very slowly is thereby prevented. In one form, the car clutch 10 is disengaged by a servomotor 16 acting through links &c. 12 when a car speed sensitive valve 26 and an engine speed sensitive valve 23 are opened to connect the servomotor to a vacuum tank 18. The car speed sensitive valve 26 has a closed position, as shown, to disconnect the engine speed sensitive valve 23 &c. from the servomotor, when a car speed sensitive switch 66 is opened below a predetermined car speed to de-energize a solenoid 65. Included in the circuit energizing the solenoid 65 is a switch 67 actuated by the car gear shift lever and two parallel circuits 68, 69, the former including a switch 71 closed on release of the accelerator pedal. The gear shift switch 67 makes the circuit 69 when first or second ratios are provided, and makes the circuit 68 when third or forth ratios are established. The arrangement is such that, while the car is moving at a road speed exceeding the predetermined speed, the solenoid 65 is de-energized by opening of the speed sensitive switch 66 and the servomotor 16 is cut-off from the engine speed sensitive valve 23 and the vacuum tank 18. The solenoid 65 is also de-energized below the predetermined road speed if the third or fourth ratio is established and the accelerator pedal is depressed to open the switch 71. If the car is stationary or moving very slowly, and either the first or second ratios are established, or the third or fourth ratios are established and the accelerator pedal is released, the solenoid 65 is energized, and the servomotor 16 is connected to the engine speed sensitive valve 23, which accordingly effects engagement and disengagement of the main clutch 10. When the solenoid 65 is deenergized, the servomotor 17 is connected to atmosphere through a port 59. The engine speed sensitive valve 23 comprises an enginedriven governor 42 coupled to a diaphragm 37 and so operated that at low engine speed the diaphragm is pulled downwards of the Figure to open a port 38 and connect the vacuum tank 18 to the car speed controlled valve 26, at higher engine speeds a spool element 41 being engaged to close the port 38 and instead open a port 39 to atmosphere. The vacuum tank 18 is evacuated either through the inlet manifold of the car engine or by an exhauster, and is connected through a pressure-regulating valve 22 to the engine speed control valve 23. In one modification, Fig. 2 (not shown), the pressure fluid is compressed air, instead of vacuum. In another modification, Fig. 3 (also not shown), in which the pressure fluid is vacuum, the electric circuit controlling the car speed sensitive valve 26 is replaced by a system of three valves using vacuum power and operated in accordance with car speed, gear shift lever position and accelerator pedal position, respectively, to effect a similar isolation of the engine speed sensitive valve from the servomotor.