Patent GB-700342-A (GB)
Title: Improvements in hydraulic power transmission devices
IPC: F16H61/62
Filed: 1948-05-25
Abstract: 700,342. Torque converters; fluid pressure servomotor control systems. AKTIEBOLAGET LJUNGSTROMS ANGTURBIN. May 25, 1948 [July 10, 1947], No. 14083/48. [A Specification was laid open to inspection under Sect. 91 of the Acts, Nov. 29, 1948.] Classes 69 (2) and 135. [Also in Group XXIV] A hydraulic power transmission device having a rotatable casing rigidly carrying a primary member (pump member) and enclosing a secondary member (turbine member) and a reaction member (guide van member) rotatably mounted in a stationary housing, includes a clutch for connecting the reaction member to the primary member and means for mechanically connecting the reaction member to the secondary member in order to obtain direct drive between the primary and secondary members. In Fig. 1 a pump member 24 rigid with a shell 54 is rotated by a crankshaft 10 and flywheel 12 of an internal combustion engine. A turbine member 40 having blades 34 and 36 is carried by a shaft 44 and a reaction member 50 is carried by a hollow shaft 48 having fixed to it an extension 62. The shaft 44 is journalled at one end in a fixed casing composed of members 16a, 16b rigidly attached to an engine casing 18 by means of a ball bearing 60. At the other end the shaft 44 is supported by a ball bearing 58 mounted in a pump member 24. A free-wheel clutch 110 is provided between the shaft 44 of the turbine and the shaft 48 of the reaction member to prevent the reaction member from rotating faster than the turbine member. A second free-wheel 118 prevents the reaction member from rotating in a direction opposite to the normal direction of rotation of the secondary member. When it is desired to effect a direction coupling between the pump member and the turbine member a known synchronized claw clutch 120 is shifted to the left to couple a sleeve 122 fixed to the shell 54 to the extension 62. Splines 132 prevent the engagement of the clutch by preventing axial movement of the sleeve 136 as long as the pump casing has a higher speed than the guide member. Splines 130 have a small clearance in a radial direction but a large clearance in a circumferential direction. Springs act between a shoulder 116 and the end surface of the sleeve 128 and press the sleeve against a conical surface 126. To engage the direct drive the fuel supply to the engine is momentarily throttled so that the guide member shaft overruns the pump casing speed. A relief valve 98 prevents excessive pressure in the coupling. The liquid supply is cooled by a cooler 80. In a modification the connection between the shell and the extension is provided by a friction clutch which can be engaged by operation of a forked lever. One clutch member is carried by the shell and the other by a hubmember splined to the extension 62. A spring disc bearing on a disc by which the clutch members can be pressed together. In another modification the clutch between the shell and the extension 62 comprises a centrifugally operated clutch which engages as soon as the reaction member rotates at a sufficiently high speed. In this case the extension 62 is formed with a flange supporting a ring having an outer rim of U-shaped cross section containing a plurality of centrifugal weights each weight being pressed towards the ring by a resilient pin which exerts a comparatively small force which must only ensure that when the guide member is stationary the weights are held out of contact with a brake band fixed to a ring member projecting from the pump casing. The ring has an annular lip cooperating with an annular lip on the interior of the fixed casing to maintain the braking surfaces dry. As soon as a stage of operation is reached at which the guide member starts to rotate in the same direction as the pump member centrifugal force acting on the weights causes them to lock the shell to the reaction member. As soon as the engine torque is higher than the maximum torque transferable through the clutch, return from direct drive to converter drive occurs. In Fig. 5 to connect the reaction member to the shell a friction clutch 256 is engagable by means of a liquid pressure operated device operation of which can be initiated either manually by a lever 298 or centrifugally. An annular member 258 carried by a flange of the extension 62 is axially movable. Liquid pressure supplied to a space 264 applies pressure to the plates 254, 270 of the clutch. The liquid is supplied to the space 264 from a chamber in the coupling which is in connection with the discharge side of a pump 74. The liquid is controlled by a valve 268 which it reaches through a passage 266. The valve can either be operated by a centrifugal weight 278 (Fig. 6) which opens the valve in swinging from position a to position b or can be operated by the lever 298 which rotates a member 292 having square threads which cooperate with square threads on a member 290. Operation of the lever rotates the member 292 which is thus moved axially by the threads to control the valve. Springs urge the lever to neutral position. Fig. 11 shows an arrangement in which the reaction member can either be held fixed or allowed to rotate in a reverse direction during converter drive, it being connected, in the latter case to the turbine shaft through a reversing gear. When a regulating valve 396 is in a position a the guide member 50 is connected to the turbine shaft only by reversing gear 366, 368, 370. If the valve is shifted to a position b a servomotor 362 is connected to a pressure pipe 392 so that the servomotor piston is moved to cause locking of the guide member to the fixed housing by means of a brake 358. When the valve is moved to a position c the servomotor 362 reverts to its original position but a servomotor 352 is operated and a valve 350 is moved into a position in which liquid is supplied to the chamber 264 of the clutch and brings about its engagement. Direct drive is thus established. A device 410 is merely operative to lift the brake band from the brake drum as soon as the brake is released. A gear pump 380 driven from a member 122 attached to the shell 54 supplies liquid under pressure for the coupling and for operating the servomotors. In a modification of Fig. 11 planet gears are mounted on shafts directly connected to the stationary housing of the converter. These gears mesh with a toothed rim on the member 252 and with a gear journalled through the medium of a oneway clutch on a sleeve on the turbine shaft. The connection between the reaction member and the turbine member may be by means of a self locking brake. The member preventing rotation in one direction of the reaction member may be a self locking brake or automatic claw coupling. The reversing gear of Fig. 11 and its modification may comprise conical gears to provide for changing the gear ratio. Specification 700,443 is referred to.