Dual hydraulic machine transmission

Abstract

The modular transmission uses only a pair of small and light hydraulic machines of remarkably improved volumetric efficiency with pistons having body portions substantially as long as the axial length of the respective cylinders in which they reciprocate. The two hydraulic machines operate in a closed loop, one being used as a pump driven by the vehicle's engine, and the other used as a motor. Each machine has a fully articulatable swash plate. By computer control, the angles of the swash plates of the two machines are infinitely varied to provide an appropriate optimum ratio of engine/wheel speed for all conditions from start-up, city driving, hill climbing varied according to load and steepness, and over-drive for highway. This complete vehicle operation is attained while the vehicle's engine continues to operate at relatively constant speeds and relatively low RPM.

1 - 10 . (canceled) 
   
   
       11 . A method of replacing an automatic transmission in a transmission well of an automobile having an engine, an engine drive shaft driven by the engine, and a wheel drive shaft for driving a plurality of wheels to move the automobile, the method comprising the steps of:
 a) disconnecting the automatic transmission from the engine drive shaft and the wheel drive shaft;   b) removing the automatic transmission from the transmission well;   c) placing a hydraulic transmission comprising a pump and a motor completely within the transmission well;   d) attaching the engine drive shaft to the pump and the wheel drive shaft to the motor; and   e) providing a computer control to control operation of the hydraulic transmission;   wherein the hydraulic transmission replaces the automatic transmission and converts torque and power from the engine to provide enough torque and power to the wheel drive shaft to move the automobile from a stationary state to a highway speed.   
   
   
       12 . The method of  claim 11 , wherein the engine is a homogeneous-charge-compression-ignition type engine. 
   
   
       13 . A method of controlling power to a wheel drive shaft of an automobile having an engine, a drive mode selector, an accelerator pedal, a brake pedal, and a transmission comprising a pump swash plate having an adjustable swash plate angle and a motor swash plate having an adjustable swash plate angle, the method comprising the steps of:
 a) measuring a drive mode selector position, an accelerator pedal position, and a brake pedal position;   b) measuring an engine speed and an automobile speed; and   c) controlling the pump swash plate angle and the motor swash plate angle based on the drive mode selector position, the accelerator pedal position, the brake pedal position, the engine speed, and the automobile speed while maintaining a constant engine speed within predetermined values of the pump swash plate angle and the motor swash plate angle.   
   
   
       14 . The method of  claim 13 , wherein the engine is a homogeneous-charge-compression-ignition type engine. 
   
   
       15 . The method of  claim 13  further comprising the steps of:
 d) increasing the engine speed only when the pump swash plate angle and the motor swash plate angle reach predetermined values and more power to the wheel drive shaft is required; and   e) decreasing the engine speed only when the engine speed is above idle and less power to the wheel drive shaft is required.   
   
   
       16 . A method of controlling power to a wheel drive shaft of an automobile having an engine having an auxiliary drive shaft extending from the front of and driven by the engine and a main drive shaft extending from the rear of and driven by the engine, the method comprising the steps of:
 a) driving a hydraulic module, comprising a hydraulic pump in a closed loop with a hydraulic motor, using the auxiliary drive shaft to produce a hydraulic output from the hydraulic motor;   b) mechanically coupling the hydraulic output to the wheel drive shaft to provide power to the wheel drive shaft; and   c) infinitely varying the power to the wheel drive shaft by adjusting a pump swash plate angle and a motor swash plate angle.   
   
   
       17 . The method of  claim 16  further comprising the step of mechanically coupling the main drive shaft to the wheel drive shaft, wherein the hydraulic output and the output from the main drive shaft are mechanically combined to produce a transmission output for providing power to the wheel drive shaft.