Small vehicle transmission

Abstract

A small engine transmission having a hydromechanical transmission unit providing a first power path, and a mechanical power transmission unit providing a second power path. The mechanical power transmission is a planetary gear system having a planetary carrier. The hydromechanical transmission is associated with the mechanical transmission to decrease average hydraulic power flow of the engine transmission to thereby increase operating efficiency and to permit the reduction of an output speed range to reduce transmitted power for the use of multiple modes to achieve a full torque and speed range of the transmission.

I claim:  
     
         1 . A small engine transmission, comprising 
 a hydromechanical transmission unit which includes an F unit and a V unit, an input shaft and an output shaft, providing a first power path,    a mechanical power transmission unit providing a second power path in parallel with the first power path,    the mechanical power transmission unit being a planetary gear system having a planetary carrier,    the hydromechanical transmission being so associated with the mechanical power transmission to decrease average hydraulic power flow of the small engine transmission to thereby increase operating efficiency and to permit the reduction of an output speed range to reduce transmitted power for the use of multiple modes to achieve a full torque and speed range of the transmission.    
     
     
         2 . The transmission of  claim 1  wherein the planetary carrier is an output member for the small engine transmission.  
     
     
         3 . The transmission of  claim 1  wherein the transmission has three modes of operation and wherein the third mode of operation is accomplished by adding to a second mode the planetary gear system, at least two drive gears and a clutch.  
     
     
         4 . The transmission of  claim 3  wherein a controller is associated with the small engine transmission to control the implementation of the multiple modes.  
     
     
         5 . A small engine transmission unit, comprising, 
 an HMT with three operational modes, the third mode being independent in ratio spread from the other two modes,    the third mode being comprised of a planetary, at least two associated drive gears and one clutch associated with components of the second mode.    
     
     
         6 . The transmission unit of  claim 1  wherein the F units, V units, input shaft and output shaft, rotate about separate individual axes to permit a shorter transmission length, and to accommodate different gear ratios.  
     
     
         7 . The transmission of  claim 1  wherein a jackshaft is operatively associated with the F unit and the output shaft and has its own separate axis of rotation.  
     
     
         8 . The transmission of  claim 5  wherein the planetary carrier is an output member to facilitate a transmission configuration which allows for through power transmission from a power source and through power transmission of the output member to either or both of opposite ends of the transmission.  
     
     
         9 . A small engine transmission, comprising, 
 a center housing configuration,    a pair of hydrostatic units in the center housing and including shafts and drive gears, a hydraulic reservoir, and a clutch assembly,    a pair of end covers on opposite ends of the center housing and containing at least one of mechanical shafts, non-hydrostatic transmission drive gears, transmission mounting and a second clutch assembly.    
     
     
         10 . The transmission of  claim 9  where the center housing configuration also contains a solenoid, a valve and a yoke for shifting the second clutch assembly.  
     
     
         11 . The transmission of  claim 9  wherein the center section configuration also contains components for a first second operation mode and a clutch assembly.  
     
     
         12 . The transmission of  claim 9  wherein the transmission allows for one or more engine/transmission features including at least one of gears, hydraulic pump, housing or controller components and functions.