Cylinder block assembly for hydraulic unit

Abstract

A cylinder block assembly of a hydraulic unit includes a cylinder block having a plurality of piston bores arranged circumferentially about a central axis of the cylinder block assembly and extending through a first face of the cylinder block. Each of the piston bores has a pitch diameter defined radially with respect to the central axis of the cylinder block assembly. A second face of the cylinder block has pressure ports that extend from the piston bores. The cylinder block assembly further includes a balance plate coupled to the second face of the cylinder block. The balance plate includes apertures that align with the pressure ports, where a cylinder block assembly outer length is defined between the first face of the cylinder block and an outer face of the balance plate. A ratio of the pitch diameter to the cylinder block assembly outer length is between 1.24 and 1.27.

What is claimed is: 
     
         1 . A cylinder block assembly of a hydraulic unit, the cylinder block assembly comprising:
 a cylinder block having a plurality of piston bores arranged circumferentially about a central axis of the cylinder block assembly and extending through a first face of the cylinder block, each of the piston bores having a pitch diameter defined radially with respect to the central axis of the cylinder block assembly, the cylinder block further comprising a second face having a plurality of pressure ports that extend from the piston bores, wherein each of the pressure ports has a smaller diameter than a piston bore diameter of each of the piston bores; and   a balance plate coupled to the second face of the cylinder block, the balance plate comprising a plurality of apertures that align with the pressure ports, wherein a cylinder block assembly outer length is defined between the first face of the cylinder block and an outer face of the balance plate, and a ratio of the pitch diameter to the cylinder block assembly outer length is between 1.24 and 1.27.   
     
     
         2 . The cylinder block assembly of  claim 1 , wherein a ratio of the pitch diameter to the piston bore diameter is between 3.44 and 3.48. 
     
     
         3 . The cylinder block assembly of  claim 1 , wherein a ratio of the cylinder block assembly outer length to the piston bore diameter is between 2.73 and 2.77. 
     
     
         4 . The cylinder block assembly of  claim 1 , wherein the outer face of the balance plate defines a balance land having a balance land inner diameter and a balance land outer diameter, and a ratio of the balance land outer diameter to the pitch diameter is between 1.23 and 1.25. 
     
     
         5 . The cylinder block assembly of  claim 4 , wherein a ratio of the balance land outer diameter to the piston bore diameter is between 4.28 and 4.32. 
     
     
         6 . The cylinder block assembly of  claim 4 , wherein a ratio of the balance land inner diameter to the pitch diameter is between 0.75 and 0.77. 
     
     
         7 . The cylinder block assembly of  claim 4 , wherein a ratio of the balance land inner diameter to the piston bore diameter is between 2.60 and 2.65. 
     
     
         8 . The cylinder block assembly of  claim 4 , wherein a ratio of the balance land outer diameter to the balance land inner diameter is between 1.62 and 1.65. 
     
     
         9 . The cylinder block assembly of  claim 1 , wherein a piston relief having a piston relief diameter is defined between each pairing of the piston bores and the pressure ports, and a ratio of the piston relief diameter to the piston bore diameter is between 1.02 and 1.05. 
     
     
         10 . The cylinder block assembly of  claim 1 , further comprising a shaft interface that extends from the first face of the cylinder block, the shaft interface having a smaller diameter than the pitch diameter, wherein a cylinder block assembly total length is defined between an outer edge of the shaft interface and the outer face of the balance plate, and a ratio of the cylinder block assembly total length to the cylinder block assembly outer length is between 1.28 and 1.30. 
     
     
         11 . A method of assembling a hydraulic unit, the method comprising:
 biasing a cylinder block assembly toward a port plate, the cylinder block assembly having a plurality of piston bores arranged circumferentially about a central axis of the cylinder block assembly and extending through a first face of the cylinder block, each of the piston bores having a pitch diameter defined radially with respect to the central axis of the cylinder block assembly, the cylinder block further comprising a second face having a plurality of pressure ports that extend from the piston bores, wherein each of the pressure ports has a smaller diameter than a piston bore diameter of each of the piston bores, and a balance plate coupled to the second face of the cylinder block, the balance plate comprising a plurality of apertures that align with the pressure ports, wherein a cylinder block assembly outer length is defined between the first face of the cylinder block and an outer face of the balance plate proximate the port plate, and a ratio of the pitch diameter to the cylinder block assembly outer length is between 1.24 and 1.27;   arranging a plurality of pistons in the piston bores; and   interfacing the cylinder block assembly with a shaft.   
     
     
         12 . The method of  claim 11 , wherein a ratio of the pitch diameter to the piston bore diameter is between 3.44 and 3.48, and a ratio of the cylinder block assembly outer length to the piston bore diameter is between 2.73 and 2.77. 
     
     
         13 . The method of  claim 11 , wherein the outer face of the balance plate defines a balance land having a balance land inner diameter and a balance land outer diameter, a ratio of the balance land outer diameter to the pitch diameter is between 1.23 and 1.25, a ratio of the balance land outer diameter to the piston bore diameter is between 4.28 and 4.32, and a ratio of the balance land outer diameter to the balance land inner diameter is between 1.62 and 1.65. 
     
     
         14 . The method of  claim 11 , wherein a piston relief having a piston relief diameter is defined between each pairing of the piston bores and the pressure ports, and a ratio of the piston relief diameter to the piston bore diameter is between 1.02 and 1.05. 
     
     
         15 . The method of  claim 11 , wherein the cylinder block assembly further comprises a shaft interface that extends from the first face of the cylinder block, the shaft interface having a smaller diameter than the pitch diameter, wherein a cylinder block assembly total length is defined between an outer edge of the shaft interface and the outer face of the balance plate, and a ratio of the cylinder block assembly total length to the cylinder block assembly outer length is between 1.28 and 1.30.