Zahnradfabrik Friedrichshafen, Ag.

Hansjorg Dach

Robert Marion

Anton Ott

Horst Furtner

Karlheinz Schachmann

An infinitely variable compound transmission has a tripartite hydrodynamic torque converter having a pump, a turbine member and a guide member relatively rotatable about a common axis. An input pump shaft normally driven by an engine is connected to the pump, a guide shaft is connected to the guide member and coaxial with the pump shaft, and a turbine shaft coaxial with the guide and pump shafts is connected to the turbine member. A brake connected to the turbine shaft is energizable for immobilizing the turbine shaft against rotation. A coupling clutch connected between the turbine shaft and the guide shaft is actuatable for joint rotation of same about the axis. A bypass clutch is actuatable for connecting the pump shaft to one of the members. An infinitely variable belt transmission operatively connected to the guide shaft has an output shaft connectable to a load. In a starting position, only the coupling clutch is actuated with the brake and bypass clutch unactuated for driving the turbine and guide shafts purely hydraulically. In a forward drive position, both the bypass and coupling clutches are actuated with the brake unactuated for positively coupling the guide shaft and the shaft of the one member. In a reverse starting and drive position, the brake is actuated with the clutches both unactuated for reverse driving the guide shaft purely hydraulically.

Infinitely variable compound transmission

A hydraulic control system of the type disclosed in U.S. Pat. No. 3,938,410 is improved by providing a 2-3 shift valve which connects a direct passage and a throttle-containing passage to the control valve for the second clutch or brake (second-friction device) while the pressure in the first clutch or brake (first friction device) is applied to one side of the second control valve, a restoring spring acting upon the opposite side of this second control valve. This valve establishes a threshold for the pressure in the first friction device such that the direct passage is connected to the second friction device below the threshold while the throttle-containing passage is connected to the second friction device at or above this threshold.

Hydraulic actuating system for a pair of concurrently operating friction

To control the changeover between different speed ratios in an automotive transmission, with the aid of hydraulically actuatable clutches and brakes, a 1-2 shift valve (70) and a 2-3 shift valve (90) responsive to a speed-dependent fluid pressure are subjected to a countervailing load-dependent fluid pressure generated by a throttle valve (40), under the control of the vehicular accelerator, above a predetermined intermediate point of the load range. Fluid for the actuation of the clutches and brakes, under a pressure rising in the lower part of the load range and remaining constant in its upper part, is delivered by a modulating valve (340) in cascade with the throttle valve, provided with a limitedly displaceable slider, or by cascaded modulating and limiting valves (350, 357).

Hydraulic gear-shift control for automotive transmission systems

A hydraulic speed-changing system for an automotive transmission includes a clutch K2 actuatable by a control valve with associated damper which delays full operation of the clutch to smooth the cut-in. The same clutch is used in third gear and in reverse, its actuation being accompanied in the latter instance by that of a brake B2. Fluid pressure used to control the operation of this brake is also utilized to exert upon the control valve of clutch K2 a supplemental force reducing the delay period of the damper.

Hydraulic speed-changing system

Two concurrently operated hydraulic brakes of an automotive transmission, actuated in an intermediate-speed ('second gear') position, are filled under the control of a slide valve whose slider in a normal position admits fluid at high rate to both brakes and thereafter assumes an unstable throttling position in which the fluid pressure gradually builds up in them to a value causing an associated plunger to return the slider to normal. One of the brakes, which is only unidirectionally effective, remains actuated also upon an upshift into a high-speed position ('third gear') whereas the other, bidirectionally effective brake is released upon such upshift under the control of a shift valve which cuts off the fluid flow to the latter brake and establishes a drainage path therefor by passing the slide valve.

Growing community of inventors

Friedrichshafen, Germany

Hansjorg Dach