Hydraulic machine with a threaded central pin for setting machine preload

Abstract

Systems and methods for a hydraulic machine. The hydraulic machine includes, in one example, a rotational shaft, a central pin rotationally coupled to the rotational shaft and threadingly engaged with a cylinder block via a threaded interface, and pistons coupled to the rotational shaft and mated with cylinders in the cylinder block. The hydraulic machine further includes a distribution plate in fluidic communication with the cylinders and a fluid inlet and a fluid outlet.

1 . A hydraulic machine, comprising:
 a rotational shaft;   a central pin rotationally coupled to the rotational shaft and threadingly engaged with a cylinder block via a threaded interface;   a plurality of pistons coupled to the rotational shaft and mated with a plurality of cylinders in the cylinder block; and   a distribution plate in fluidic communication with the plurality of cylinders and a fluid inlet and a fluid outlet.   
     
     
         2 . The hydraulic machine of  claim 1 , further comprising a threaded retainer ring positioned in the cylinder block and axially delimiting the central pin. 
     
     
         3 . The hydraulic machine of  claim 1 , further comprising a tailstock pin threadingly engaged with the distribution plate and mated with a central recess in the cylinder block. 
     
     
         4 . The hydraulic machine of  claim 3 , further comprising a seal formed between the tailstock pin, the cylinder block, and the distribution plate. 
     
     
         5 . The hydraulic machine of  claim 1 , further comprising a seal formed between the distribution plate and the cylinder block. 
     
     
         6 . The hydraulic machine of  claim 1 , wherein an interface between the central pin and the cylinder block does not include a spring. 
     
     
         7 . The hydraulic machine of  claim 1 , further comprising a bearing coupled to the rotational shaft and a housing. 
     
     
         8 . The hydraulic machine of  claim 1 , wherein the hydraulic machine is a bent axis hydraulic motor. 
     
     
         9 . The hydraulic machine of  claim 8 , wherein the bend axis hydraulic motor is included in a hydrostatic transmission. 
     
     
         10 . A method for operation of a first hydraulic machine, comprising:
 rotating a rotational shaft while a preload force is exerted on a distribution plate by a cylinder block;   wherein an amount of preload force is dictated by an amount of threaded engagement between a central pin and the cylinder block; and   wherein the first hydraulic machine includes:
 the rotational shaft; 
 the central pin rotationally coupled to the rotational shaft and threadingly engaged with the cylinder block; 
 a plurality of pistons coupled to the rotational shaft and mated with a plurality of cylinders in the cylinder block; and 
 the distribution plate in fluidic communication with the plurality of cylinders and a fluid inlet and a fluid outlet. 
   
     
     
         11 . The method of  claim 10 , further comprising flowing a fluid from the fluid outlet to a second hydraulic machine. 
     
     
         12 . The method of  claim 11 , wherein the second hydraulic machine is a hydraulic pump. 
     
     
         13 . The method of  claim 12 , wherein the hydraulic pump is included in a hydrostatic transmission. 
     
     
         14 . A bent axis hydraulic machine, comprising:
 a rotational shaft;   a central pin rotationally coupled to the rotational shaft and threadingly engaged with a cylinder block;   a plurality of pistons coupled to the rotational shaft and mated with a plurality of cylinders in the cylinder block; and   a distribution plate in fluidic communication with the plurality of cylinders and a fluid inlet and a fluid outlet;   wherein the cylinder block exerts a preload force on the distribution plate that is based on an amount of threaded engagement between the central pin and the cylinder block.   
     
     
         15 . The bent axis hydraulic machine of  claim 14 , further comprising a tailstock pin threadingly engaged with the distribution plate, mated with a central recess in the cylinder block, and in face sharing contact with an end of the central pin. 
     
     
         16 . The bent axis hydraulic machine of  claim 14 , further comprising a sealing assembly configured to seal the cylinder block and the distribution plate. 
     
     
         17 . The bent axis hydraulic machine of  claim 16 , wherein the sealing assembly includes a first seal which is arranged between the cylinder block and the distribution plate and positioned radially outward from the fluid inlet and the fluid outlet. 
     
     
         18 . The bent axis hydraulic machine of  claim 17 , wherein the sealing assembly includes a second seal which is arranged between the cylinder block, the distribution plate, and a tailstock pin threadingly engaged with the distribution plate, mated with a central recess in the cylinder block. 
     
     
         19 . The bent axis hydraulic machine of  claim 14 , wherein the bent axis hydraulic machine is a bent axis motor that is in fluidic communication with a hydraulic pump. 
     
     
         20 . The bent axis hydraulic machine of  claim 14 , wherein the central pin does not include a spring positioned therein or directly coupled thereto.