Patent GB-964512-A (GB)
Title: Improvements in or relating to clutch control systems for vehicles
Inventor: BLAND ALBERT NORMAN
IPC: F16H63/46
Filed: 1959-12-15
Abstract: 964,512. Clutch control. AUTOMOTIVE PRODUCTS CO. Ltd. Dec. 7, 1960 [Dec. 15, 1959], No. 42656/59. Heading F2L. In a control for a spring-engaged friction clutch 10 in a motor vehicle, clutch disengagement is effected by a servomotor 17 actuated by positive (Fig. 2, not shown) or, as shown, negative gaseous pressure operative under the independent controls of a valve, such as 22, actuated by an engine driven centrifugal governor 58 to simulate a centrifugal clutch effect and a valve, such as 23, manually actuated by movement of the vehicle gear lever during shift, and for clutch re-engagement following governorvalve-controlled disengagement the venting of the servomotor 17 is controlled by a valve, such as 62, so that the rate of re-engagement relative to the rate of increase of engine speed during such re-engagement decreases as said rate of increase of engine speed rises. As shown, during engine idling with first or second gear selected, negative pressure in a reservoir 19 evacuated through a non-return valve 21 by inlet manifold suction or an exhauster is connected to the servomotor 17 through a regulator valve 24 controlling the maximum disengaging pressure differential, a port 55 in the valve 22, a line 59, a one-way valve 61, a port 81 in a vehicle speed responsive valve 63, and a port 45 in a changeover valve 39. With increase in engine speed the governor 58 moves a diaphragm 54 in the valve 22 to close the port 55 and open a port 56 and the servomotor 17 is vented through the valves 39, 63, the valve 62 and the line 59. The engagement control valve 62 comprises chambers 65, 64 respectively connected to the line 59 and the valve 63, a closure member 72 which opens against a spring 73 for initial pressure balance between the chambers 65, 64, the usual bleed hole 71 providing slow residual balance for gradual smooth final clutch engagement, and a stem 75 between the closure member 72 and a diaphragm 68 separating the chamber 65 and a chamber 66 which latter is connected to the reservoir 19 through the regulator valve 24. A spring 74 acts on the diaphragm 68 and the stem 75 to produce a thrust which retards the seating of the closure member 72 and depends on the difference between the pressures in the chambers 65, 66. The pressure in the chamber 65 depends on the degree of opening of the port 56 in the governor valve 22. If the engine speed is increased slowly the port 56 is opened slowly and the servomotor can follow-up the valve movement, the pressure in the chamber 65 not rising greatly above that in the chamber 64. If, on the other hand, the engine speed is increased rapidly the greater pressure difference between the chambers 64, 65 tends to retard closure of the member 72; however, the higher pressure in the chamber 65 over that in the chamber 66 also acts to oppose the opening thrust on the member 72 of the spring 74 so that the member 72 is able to close, the parts being so arranged that the loss of opening thrust on the member 72 more than compensates for the closure-retarding effect due to the greater pressure difference between the chambers 64, 65, and the rate at which the member 72 approaches its seat is increased, with corresponding reduction in the rate of clutch engagement. The changeover valve 39 comprises chambers 42, 43 respectively connected to the valve 63 and the servomotor 17, and a valve member 49 which is movable between seats around the port 45 and a port 46 connecting the chamber 42 to the regulator valve 24 and is carried by a stem 48 mounted on a diaphragm which is loaded by a spring 51 and separates the chamber 42 from a chamber 38 which is connected to the reservoir 19 through the valve 23 mounted on the gear shift lever. The vehicle speed responsive valve 63 comprises chambers 78, 77 respectively connected to the valve 39 and a further engagement control valve 83, and a valve member 82 which is urged to close the port 81 by a spring 84 and is moved to close a port 79 by energization of a solenoid 85. The circuit of the solenoid includes a switch 86 which is closed to energize the solenoid 85 below a predetermined vehicle speed, e.g. 10 m.p.h., and a changeover switch 87 which is coupled to the gear change mechanism so that when a lower gear, e.g. first or second, is selected it assumes a first position completing the circuit when the switch 86 is closed, and when a higher gear is selected it assumes a second position in which the circuit may only be completed by closure of a switch 88 closed by accelerator pedal release. If, when the vehicle exceeds 10 m.p.h. and the valve member 82 in the valve 63 closes the port 81, the gear shift lever is moved to change gear, the chamber 38 in the valve 39 is connected to the reservoir 19 to open and close the ports 46, 45 respectively to actuate the servomotor 17 and disengage the clutch. On release of the gear shift lever the servomotor 17 is vented, for clutch re-engagement, through the valves 39, 63 and the valve 83 which is similar to the valve 62 except that a chamber 65a is connected directly to atmosphere and a chamber 66a is connected to the engine inlet manifold and which provides that the rate of clutch engagement is increased as the engine throttle is opened, the opening thrust on a closure member 72a due to a spring 74a increasing with reduction of suction in the chamber 66a. Alternatively, for use with a compression ignition engine, the inlet manifold pressure responsive means may be replaced by a tapered needle, variable venting orifice upstream of the valve 83 which orifice is opened to vary the rate of clutch engagement as the vehicle accelerator pedal is depressed. In Fig. 2, not shown, wherein the clutch disengaging servomotor is actuated by compressed air, the valves correspond to those in Fig. 1, the second engagement control valve operative during re-engagement of the clutch after gear shift valve controlled-disengagement being provided with the aforementioned accelerator pedal position-dependent, tapered needle, variable venting orifice. Specification 964,511 is referred to.