Patent GB-693976-A (GB)
Title: Improvements in hydro-dynamic power transmission devices
IPC: F16H61/54
Filed: 1950-06-14
Abstract: 693,976. Hydrodynamic power transmission devices. AKTIEBOLAGET LJUNGSTROMS ANGTURB1N. June 14, 1950 [June 15, 1949], No. 14845/50. Class 69(ii) A hydrodynamic power transmission device having an hydraulic circuit containing in the working chamber a pump member and a turbine member and also a reverse blade ring arranged to be inserted into or withdrawn from the circuit ahead of the inlet of the turbine member for backward or forward drive respectively, includes at least one additional guide blade ring disposed between the turbine outlet and the inlet of the pump member and connected to the reverse blade ring, the guide blade ring being adapted to be rendered inoperative when the power transmission device is to operate as an hydraulic coupling and an annular disc or like supporting member arranged in an inner core of the working chamber of the hydraulic circuit and rigidly interconnecting the blade rings located respectively ahead of the pump member and. of the turbine member, the supporting member being movable axially for inserting the blade rings connected with the member into the hydraulic circuit or retracting the same from the circuit. In a modification the reverse blade ring and a screen disposed ahead of the turbine inlet are displaceable by means of a supporting member arranged coaxial with the transmission while the additional guide blade ring ahead of the pump inlet is mounted on a free-wheel separate from the supporting member and providing for rotation of this blade ring in the same direction as the pump. The object of the invention is to provide a blade system of simple construction which produces a combined forward and backward coupling or torque converter with equal or almost equal input torque or speed of rotation at full speed, forward speed, and backward speed and with a definite neutral position between these speeds. Fig. 1 shows a reversing gear comprising a ring of reversing blades 30 which can be inserted between pump blades 4 and the inlet ends of turbine blades 14. Guide blades 28 are included at the pump inlet. When a sleeve 22 which carries both reversing and guide blades is shifted to the right to a second position a screen 32 blocks off the turbine inlet and when the sleeve is shifted further the turbine inlet is opened and either further guide blades 34 or profiled spokes which allow substantially free flow of the liquid are inserted at the pump inlet. The sleeve and blades connected therewith may be rotatable or locked by a brake 38 or claw coupling or the like. In a modification an additional row of blades for slow speed in a forward direction is included between the blades 28 and 34. These blades are separated by narrow channels which reduce the quantity of liquid circulated by the pump. It is stated that the guide blade 34 may be provided with a free wheel allowing it to rotate only in the direction of the pump. In Fig. 8 the blades 28 and 34 have been replaced by a single blade ring 90 which is mounted by means of a one-way clutch 92. The reversing blades 30 and screen 32 are carried by a central axially displaceable shaft 99. Fig. 9 shows means for operating both the sleeve 22 (Fig. 1) and the brake. When a lever 100 is rocked in an axial plane the sleeve is shifted axially but if the lever is rocked in a plane perpendicular to the axis the brake is either engaged or released by means of levers 110, 114 and a shaft 1.12. The blades may be arranged radially, although embodiments are possible in which more or less inclined inlet and outlet edges may be more advantageous. In order to obtain a flat efficiency curve when acting as a torque converter the inlet edges of all the blades should be rounded so that they give a good efficiency at varying angles of inlet due to varying speed ratios. The slow speed blades referred to above may be designed so that the liquid flow to the pump exerts a strong self rotating motion which means reduced torque absorption in the pump and thus reduced power from the engine with unchanged input speed. Flow diagrams are given in the Specification.