Patent GB-807395-A (GB)
Title: Improved control system for variable-speed power transmission mechanism for motor vehicles
IPC: F16D47/06
Filed: 1957-05-27
Abstract: 807,395. Controlling change-speed gearing; clutches. GENERAL MOTORS CORPORATION. May 27, 1957 [June 21, 1956], No. 16719/57. Class 80 (2). Two fluid-pressure operated clutches providing different torque paths from input to output are controlled by a first valve biased to operate one clutch and a second valve biased to exhaust the second clutch, speed-responsive means moving the second valve to engage the second clutch and pressure in the second clutch causing the first valve to exhaust the first clutch. Function.-In a vehicle transmission power input from a shaft 10 drives through bevels 11, 12 to a clutch drum 14 containing two fluidpressure-operated clutches which are engageable to connect the drum 14 directly to an intermediate shaft 50 or through a torque-converter A and one-way clutch 36 to the shaft 50. The shaft 50 provides the input to a planetary gear C which provides a direct drive to an output shaft 110 by engagement of a plate clutch, low ratio drive by engagement of a cone brake and reverse drive by engagement of a positive detent, the clutch, brake and detent being hydraulically operated. An engine-driven pump 150 supplies high-pressure fluid to a valve body 165 containing a forward and reverse valve 167 operated by a lever 169 interlocked, by detent 173, by service brake pressure against accidental reverse engagement, and a direct or low-speed valve 192 operated by a driver's switch 248. The direct drive and torque-converter clutches are controlled by two valves 214 and 213 respectively, which control the admission of lower pressure fluid to the clutches. The valve 213 is biased by a spring 226 to allow fluid from a duct 163 to pass to a converter clutch engaging passage 38, and the valve 214 is biased by a spring 227a to connect a direct-drive clutch passage 37 to exhaust 219. A speed-responsive switch 247 on the output shaft closes at a predetermined vehicle speed to energize a solenoid valve 212 to pass pressure-fluid from a duct 163a to move the valve 214 to connect passage 37 with the pressure supply 163 and engage the direct-drive clutch. Pressure from the direct drive clutch is led by a passage 39 to move the valve 213 to exhaust the converter clutch, giving torque overlap between the direct and converter drives. Manual engagement of the converter clutch to provide hydrodynamic braking is provided by a switch 240 controlling a solenoid valve 210 admitting pressure to assist the spring 226. Kickdown to converter drive at high speeds is provided by a switch 250 which de-energizes the valve 212 and allows the valve 214 to return to its biased position. Direct and converter clutch.-The clutch unit B (Fig. 2) comprises a drum 14 drivingly connected to the input shaft 13 and having a radial plate 15 with a wall portion 44 forming an annular chamber 58 with a piston 45 therein, and a wall portion 46 forming a second annular chamber 65a co-operating with an external cylinder 47. The piston 45 is rotationally rigid with the plate 15 through a pin 49. An annular backing-plate 54 is secured by a snap-ring 56 to an inner wall 53 of the plate 15 and forms an abutment for springs 57 which retract the piston 45 on release of pressure in chamber 58. The piston has an external conical surface 71 between which and a conical surface on a ring 70 secured to the plate 15 is a cone clutch plate 19. The plate 19 is splined by a boss 20 to a tubular shaft 21 integral with the impeller 22 of the torque converter A. Within the drum 14 are splined a pair of clutch presser plates 40, 41 engaging, together with a facing 42, with clutchfriction plates 16, 17 splined through a hub 18 to the intermediate shaft 50. The presser plate 40 is connected by bolts 68 and a flanged ring 67 with the outer periphery of a Belleville washer 66 fulcrumed on bushes 61 secured to the plate 15, the washer being engaged at its inner edge by a flange 62 on the cylinder 47, such that pressure-fluid admitted to the cylinder stresses the Belleville washer to engage the clutch. Pressure fluid for clutch engagement is fed to ducts 37, 38 in a housing 101, having crescentshaped chambers 77, 85 opening to the sets of axial grooves 78, 79, 80, and 86, 87, 88 leading to grooves 72, 74 to supply the chambers 58 and 65a. The groove 74 is also connected by an axial groove 92 with the passage 39. Planetary gearing (Fig. 3). The output shaft 110 has a flange 111 forming a carrier for a set of planet pinions 112 rotatable on stub shafts 121 and meshing with a ring gear 115, rigid with a flange 51 on the intermediate shaft 50, and with a sun-gear 117 formed on a sleeve 116. The stub shafts 121 support a ring 113 formed with a sun-gear 114, a second set of planet gears 122 meshing with the sun 114 and ring-gear 115 and being supported on shafts 123 rigid with a planet carrier 124 to which a set of clutch-plates 125 is internally splined. The complementary clutchplates 127 are splined to a clutch hub 118 splined to the sleeve 116 to form a friction clutch engageable by fluid-pressure admitted from a duct 108, and passage 131, to a chamber 129 formed between a piston 128 and a flange 119 splined to the sleeve 116. The flange 119 is splined at its periphery to a conical brake plate 120 engageable between a fixed brake member 139 and a piston 143 movable against releasesprings 146 by pressure admitted through a duct 106 to a chamber 142. The planet carrier 124 is provided with a set of dogs 126 which may be engaged by dogs 135 formed on a piston 134 splined to the gear casing 104 and operable under fluid pressure from a duct 107 against a release-spring 138. This gear provides a direct drive from the intermediate shaft 50 to the output shaft 110 by engagement of the clutch 125, 127, a reduction ratio drive by release of clutch 125, 127 and engagement of the brake 120, and a reverse drive by engagement of the dogs 126, 135. In a modification of the planetary gear the release springs 146 are replaced by blade-springs, and the planetcarrier 124 is locked by a toothed bell-crank lever actuated by a pressure-fluid operated piston.