Compact Radial Piston Hydraulic Machine Having a Cylinder Block with Deforming Regions

Abstract

A hydraulic machine has a cylinder body with first and second ports and a plurality of cylinder bores disposed radially with openings through a side surface. Deformation regions, formed around each cylinder bore opening, expand and contract in response to pressure changes in the cylinder bores. A continuous band extends around the cylinder body closing the cylinder bore openings and applying a pre-stress compressive force to each deformation region. A plurality of pistons are slideably received in the plurality of cylinder bores and a plurality of valve arrangement couple the cylinder bores to the first and second ports. A shaft with an eccentric cam drives the pistons to slide within the cylinder bores. Each deformation region distorts in response to pressure in the associated cylinder bore wherein the circumference of that cylinder bore becomes more circular as the cylinder pressure increases.

1 . A hydraulic machine comprising:
 a cylinder body with a first port, a second port and a side surface, and having a plurality of cylinder bores disposed radially about an axis with each cylinder bore having an opening through the side surface, the cylinder body further having deformation regions formed around each opening, wherein the deformation regions expand and contract radially with respect to the axis in response to pressure changes in the cylinder bores;   a closing band extending around the cylinder body and closing the openings of the plurality of cylinder bores, wherein the closing band applies force to each deformation region that compresses the cylinder body;   a plurality of piston assemblies each slideably received in a different one of the plurality of cylinder bores;   a plurality of valve arrangements the plurality of cylinder bores to the first and second ports; and   a drive shaft rotatably received in the cylinder block for driving the plurality of piston assemblies within the plurality of cylinder bores.   
     
     
         2 . The hydraulic machine as recited in  claim 1  wherein the cylinder body further comprises:
 a cylinder block that has the plurality of cylinder bores and the side surface; 
 an inlet manifold having the first port; and 
 an exhaust manifold having the second port. 
 
     
     
         3 . The hydraulic machine as recited in  claim 1  wherein the side surface of the cylinder block is cylindrical and the closing band is circular. 
     
     
         4 . The hydraulic machine as recited in  claim 1  wherein the closing band extends in a continuous circle. 
     
     
         5 . The hydraulic machine as recited in  claim 1  wherein each deformation region comprises a rim extending around each cylinder bore opening and proud of the side surface. 
     
     
         6 . The hydraulic machine as recited in  claim 1  wherein each deformation region comprises a cantilevered portion of the cylinder body extending as least partially around the associated cylinder bore. 
     
     
         7 . The hydraulic machine as recited in  claim 1  wherein each deformation region expands as pressure in the adjacent cylinder bore increases and contracts as pressure in the adjacent cylinder bore decreases. 
     
     
         8 . The hydraulic machine as recited in  claim 1  wherein pressure within a given cylinder bore during a compression stage of an operating cycle reduces compressive forces that the closing band exerts on the deformation region associated with that cylinder bore. 
     
     
         9 . The hydraulic machine as recited in  claim 1  wherein as pressure within each cylinder bore increases, the adjacent deformation region flexes thereby changing a circumference of the cylinder bore from non-circular towards becoming circular. 
     
     
         10 . The hydraulic machine as recited in  claim 1  wherein each of the plurality of piston assemblies comprises a piston and a piston rod, wherein the piston rod comprises a stem with a curved shoe through which force is transferred to the drive shaft. 
     
     
         11 . The hydraulic machine as recited in  claim 10  wherein:
 the drive shaft has an eccentric cam; and 
 further comprising a cam bearing extending around the eccentric cam and having an outer race and a plurality of rollers between the outer race and the eccentric cam, wherein the shoe of each piston rod abuts the outer race. 
 
     
     
         12 . The hydraulic machine as recited in  claim 11  further comprising a retaining ring extending around the drive shaft and engaging the curved shoe of every piston rod, thereby constraining the curved shoe from moving away from the eccentric cam. 
     
     
         13 . The hydraulic machine as recited in  claim 1  wherein each of the plurality of piston assemblies comprises a piston and a piston rod, wherein the piston rod has an end with a partially spherical head that engages a partially spherical depression in the piston. 
     
     
         14 . The hydraulic machine as recited in  claim 1  wherein:
 the cylinder block comprises a plurality of first bores, each extending between the first port and one of the plurality of cylinder bores, and a plurality of second bores, each extending between the second port and one of the plurality of cylinder bores; and 
 the valve arrangement comprises a plurality of first valves, each located in one of the first bores, and a plurality of second valves, each located in one of the second bores. 
 
     
     
         15 . The hydraulic machine as recited in  claim 14  wherein each of the plurality of first valves and the plurality of second valves is a check valve. 
     
     
         16 . A hydraulic machine comprising:
 a cylinder body with a first port, a second port and a curved side surface, and including a plurality of cylinder bores disposed radially in the cylinder block with openings through the side surface and passages connecting the plurality of cylinder bores to the first and second ports, the cylinder body having a plurality of deformation regions each comprising a rim projecting outwardly from the side surface and around one of the openings, wherein the deformation regions repeatedly deform in response to pressure changes in the cylinder bores;   a closing band extending around the cylinder body and closing the openings of the plurality of cylinder bores, wherein the closing band applies compressive force to the cylinder body through the rim of each deformation region;   a plurality of piston assemblies each slideably received in a different one of the plurality of cylinder bores; and   a drive shaft rotatably received in the cylinder block and having an eccentric cam for driving the plurality of piston assemblies within the plurality of cylinder bores.   
     
     
         17 . The hydraulic machine as recited in  claim 16  further comprising a plurality of valves located in the passages of the cylinder body. 
     
     
         18 . The hydraulic machine as recited in  claim 16  wherein the cylinder body further comprises:
 a cylinder block that has the plurality of cylinder bores and the side surface; 
 an inlet manifold having the first port; and 
 an exhaust manifold having the second port. 
 
     
     
         19 . The hydraulic machine as recited in  claim 16  wherein each deformation region comprises a cantilevered portion of the cylinder body extending as least partially around the associated cylinder bore. 
     
     
         20 . The hydraulic machine as recited in  claim 19  wherein the cantilevered portion is defined by a curved cavity within the cylinder body and opening into the cylinder bore. 
     
     
         21 . The hydraulic machine as recited in  claim 16  wherein each deformation region expands as pressure in the adjacent cylinder bore increases and contracts as pressure in the adjacent cylinder bore decreases. 
     
     
         22 . The hydraulic machine as recited in  claim 16  wherein pressure within a given cylinder bore during a compression stage of an operating cycle reduces compressive forces that the closing band exerts on the deformation region associated with that cylinder bore. 
     
     
         23 . The hydraulic machine as recited in  claim 16  wherein as pressure within each cylinder bore increases, the adjacent deformation region flexes thereby changing a circumference of the cylinder bore from non-circular towards becoming circular.