Improvements in radial-type hydraulic machines

Claim 2

A hydraulic motor comprising: a. a rotatable drive shaft, b. a central cam secured to the drive shaft, c. two sets of cylinders extending radially with respect to the drive shaft, each set comprising four cylinders, the cylinders of the two sets being arranged symmetrically around the drive shaft, d. a piston arranged for axial sliding movement within each cylinder and cooperating with the cam, e. hydraulic fluid inlet and outlet ports in the cylinders, hydraulic pilot means in each cylinder including a pilot port and a pilot conduit interconnecting the pilot port and the space above the piston in an adjacent cylinder, the piston in each cylinder acting as a slide value and sequentially closing the pilot port and connecting the pilot port to the inlet and outlet ports in the cylinder to control the flow of fluid to and from the adjacent cylinder; f. the cam having two lobes, each lobe being divided symmetrically into two portions and each portion comprising successively in profile a first circular section, a first parabolic section, a spiral section, a second parabolic section, and a second circular section, whereby at any moment in an operating cycle of the motor, the combined instantaneous speeds and hydraulic fluid flow rates of all pistons travelling on a working stroke are constant and equal respectively to the maximum piston speed and maximum flow rate attained in any cylinder during the operating cycle.

Claim 3

Hydraulic motor as claimed in claim 1, wherein each first and second parabolic profile section extends over an angular width of 37* .

Claim 4

Hydraulic motor as claimed in claim 1, wherein each first and second circular profile sections extend over an angular width of 4* .

Claim 5

HyDraulic motor as claimed in claim 1, wherein each said spiral profile section extends over an angular width of 8* .

Claim 6

A hydraulic machine comprising: a. a rotatable drive shaft; b. a number of sets of cylinders extending radially with respect to the drive shaft, each set comprising four cylinders; c. hydraulic fluid inlet and outlet ports in each cylinder, d. a piston arranged for axial sliding movement within each cylinder, hydraulic pilot means in each cylinder including a pilot port and a pilot conduit interconnecting the pilot port and the space above the piston in an adjacent cylinder, the piston in each cylinder acting as a slide value and sequentially closing the pilot port and connecting the pilot port to the inlet and outlet ports in the cylinder to control the flow of fluid to and from the adjacent cylinder; e. a cam secured for rotation about the drive shaft axis relatively to the cylinders and having a number of lobes equal to the number of sets of cylinders, each lobe being similar to the others and being divided symmetrically into two portions that each comprise successively in profile a first circular section, a first parabolic section, a spiral section, a second parabolic section, and a second circular section, whereby at any moment in an operating cycle of the machine, the combine instantaneous speeds and hydraulic fluid flow rates of all pistons travelling on a working stroke are constant and equal respectively to the maximum piston speed and maximum flow rate attained in any cylinder during the operating cycle.

Claim 7

A hydraulic machine comprising: a. a rotatable drive shaft; b. a number of sets of cylinders extending radially with respect to the drive shaft, each set comprising four cylinders; c. hydraulic fluid inlet and outlet ports in each cylinder, d. a piston arranged for axial sliding movement within each cylinder, hydraulic pilot means in each cylinder including a pilot port and a pilot conduit interconnecting the pilot port and the space above the piston in an adjacent cylinder, the piston in each cylinder acting as a slide value and sequentially closing the pilot port and connecting the pilot port to the inlet and outlet ports in the cylinder to control the flow of fluid to and from the adjacent cylinder; e. a cam secured for rotation about the drive shaft axis relatively to the cylinders and having a number of lobes equal to the number of sets of cylinders, each lobe being similar to the others and being divided symmetrically into two portions that each comprise successively in profile a first circular section, a first parabolic section, a spiral section, a second parabolic section, and a second circular section, whereby at any moment in an operating cycle of the machine, the combine instantaneous speeds and hydraulic fluid flow rates of all pistons travelling on a working stroke are constant and equal respectively to the maximum piston speed and maximum flow rate attained in any cylinder during the operating cycle.