Patent GB-620047-A (GB)
Title: Improvements in or relating to compressed air clutch-control systems
IPC: B60T13/68
Filed: 1946-04-29
Abstract: 620,047. Operating clutches. REGIE NATIONALE DES USINES RENAULT. April 29, 1946, Nos. 12896, 12897, 12898 and 12899. Convention dates, Feb. 15, 1939, March 9, 1939, March 17, 1939 and April 22, 1939. [Class 80 (ii)] A compressed-air control for a single clutch 1 or a number of clutches, e.g. in a train of automotive vehicles, comprises an expansion reservoir 9, which is communicated through a valve 6 with a main clutch-control cylinder 4, so as to limit to one or more predetermined values the clutchengaging pressure during the starting interval, on completion of which the full engaging pressure is applied by means acting either manually or automatically. The air supply pressure is independent of the speed of the driving engine or engines. Two forms of operation are described, one, Fig. 1, in which the clutch 1 is disengaged by air-pressure acting on a piston 3 ; and another, Fig. 9, in which it is engaged by air-pressure on the piston. Both forms use a pair of electrically-operated control valves, 6, 7 ; and 17, 18. In Fig. 1, the clutch is disengaged by operating the valve 6 to open the pressure-line 5 to the piston 3. For starting and re-engagement, the valve 6 is returned to the Fig. 1 position, cutting the pressure-line 5 and communicating the clutch-cylinder 4 with a closed expansion chamber 9, which causes the airpressure opposing re-engagement to decrease rapidly to a predetermined value which remains constant throughout the starting period, after which a second solenoid valve 7 is operated, manually or by a time-escapement, to vent both the expansion-chamber 9 and the clutch-cylinder 4 directly to atmosphere at 8, whereupon the clutch-engaging pressure immediately reaches its full normal value. Rapid re-engagement, as for gear-shifting, is obtained by opening both valves 6, 7 together, cutting out the expansion-chamber arid directly venting the clutch-cylinder 4. In the pressure-engaged form, Fig 9, air-pressure acts on the clutch-piston 3 in opposition to a spring 15, to engage the clutch, and the expansion-- chamber 19<1> may communicate with a smaller auxiliary closed expansion-chamber 19<2> through a one-way orifice plate 13, retarding the air-flow from 19<2> to 19<1>, but not reversely, and/or through a mechanically or electrically operated valve (Figs. 12 and 13, not shown) controlled manually or by a time-escapement. In the clutch-disengaged position shown, the clutch-cylinder is directly vented through the valve 18 and both expansion chambers 191, 19<2> are rapidly filled from the pressure line 16 through the valve 17. For starting engagement, the valve 17 is closed and 18 opened, cutting off the pressure-line and supplying pressure to the clutch-cylinder from the expansion chamber 191 alone. Engaging-pressure rises rapidly to a first predetermined value which is below that required for the clutch to balance the maximum output torque of the engine, and subsequently increases slowly, either gradually or in steps in accordance with a predetermined law, to a second value as the smaller expansion-chamber 192 feeds into the larger 191 through the orifice-plate 13 and/or valve, the second valve being above that required to balance the maximum output torque. Engagement is subsequently completed at full pressure by opening the pressure-line valve 17 manually or by time-escapement. Rapid re-engagement of the clutch for gear-shifting is obtained by opening the pressure-line valve 17 directly. The auxiliary chamber 19<2> and valve arrangement may be used with the pressure-disengaged form, and the capacity of the single expansion-chamber 9, Fig. 1, may be varied by introducing variable quantities of oil.