Patent GB-868091-A (GB)
Title: Double acting clutch
IPC: F16D25/10
Filed: 1958-03-21
Abstract: 868,091. Friction clutches. BORG-WARNER CORPORATION. March 21, 1958 [April 1, 1957], No. 9146/58. Addition to 844,871. Class 80 (2). A central reaction means between two operating pistons forms two first chambers in an hydraulic clutch and a second pair of pistons form two second chambers, a plurality of one-way valves, some operating in each direction, are so arranged that certain valves are engaged by the operating pistons to prevent fluid flow at predetermined pressure differences between the first and second chambers. In a double hydraulic clutch a reaction plate 8 is axially retained on a driving shaft 1, and is contained within an annular piston housing 14 forming a cylinder for clutch-operating pistons 17, 47 slidable on the shaft 1. The piston 17 has an annular flange 23 provided with a snap-ring 24 against which seats an annular spring 25 supported off the plate 8 by brackets 26. The bore of the flange 23 is in sliding engagement with a flange 29 on an annular accelerating piston 31 sliding on the shaft and having a radial flange 35 recessed at 36. The position 35 of the piston 31 is adapted to contact the shoulders 39 of a plurality of rubber bushings 38 mounted in alternate facing directions in holes 37 in the plate 8, the opposite ends of the holes being covered by one-way flap valves 41 fixed to the plate. Drillings 34 in the flange 29 provide restricted flow between the first chamber 15 and the second chamber 75 and further drillings 21 provide a flow of cooling air to a multiplate friction clutch 106 between the driving shaft 1 and a driven gear 109. The piston 47 similarly co-operates with an accelerating piston 61 to form chambers 16, 78 for the operation of a second friction clutch 107 between the shaft 1 and a driven gear 113. In operation, with neither clutch engaged, low pressure oil is supplied to both chambers 75, 78 through conduits 3, 4 respectively, and equilibrium exists on each side of the plate 8, the springs 25, 55 biasing the pistons 17, 47 against the stops 19, 49. To engage the clutch 107 high pressure is applied to conduit 4 pressurizing chamber 78 to move piston 61 along shaft 1 until the flange 65 engages the rubber bushing 38 and thus with one-way valve 41 preventing flow from chamber 16 to chamber 15. Piston 47 then moves to the right taking with it the housing 14 and piston 17. The volume of chamber 16 increases and that of chamber 15 decreases causing a flow of fluid through the one-way valves in a left-to-right direction until the piston 47 engages the clutch 107, when the pressures in chambers 16, 15 equalize. At this stage the pressure in chamber 16 increases due to flow through the openings 64 and causes the one-way valves to shut and the piston 47 to lock up the clutch 107, the slight movement of the assembly causing excess pressure in chamber 15 to pass through openings 34 to the low-pressure circuit. Disengagement of the clutch 107 is effected by changing from high to low pressure in chamber 78, the springs 25, 55 returning the pistons to the position shown in Fig. 1 and the change in volume of chambers 15, 16 being compensated by fluid flow through the appropriate one-way valves. In a modification the accelerating pistons 31, 61 may be lightly biased away from the plate 8 by coil springs. The double clutch may be used in a two-speed countershaft gear driven through an hydraulic torque connector.