Patent GB-916485-A (GB)
Title: Improvements in or relating to continuously variable transmissions
Inventor: CREIGHTON JOHN PURCELL
IPC: F16H61/42
Filed: 1960-11-21
Abstract: 916,485. Swash-plate pumps. FORD MOTOR CO. Ltd. Nov. 14, 1961 [Nov. 21, 1960], No. 39899/60. Class 102(1). [Also in Group XXIX] A continuously-variable hydrostatic transmission comprises first and second hydraulic units connected in a closed circuit, each unit having a piston-andcylinder assembly 17, 22 and 18, 22 and a swash plate 23, 24, at least one of the swash plates being adjustable, a face valve 34, 36 maintained in phase with each of the swash plates and having ports co-operating with the ports of the cylinders of the respective assembly, the two face valves being in abutting face relationship on their faces remote from the cylinder ports and the abutting faces being provided with registering annular grooves 37, 38 in communication with the respective ports in the face valves. The piston-and-cylinder assemblies are connected by crowned splines 19, 21 to the input shaft 11, and the swash plate 24 of the motor is connected by splines 27 to the output shaft 12. The swash plate 23 of the pump is non-rotatable and automatically or manually adjustable about an axis 28 to vary the stroke of the pistons 22 of the pump, the pistons being urged by springs 33 into engagement with slippers 29 on the swash plate. The swash plate 24 of the motor is connected by a housing 26 to its associated valve plate 36 which abuts a port plate 31 cooperating with the cylinders in the assembly 18, 22. The valve plate 34 of the pump abuts a port plate 31 co-operating with the cylinders in the assembly 17, 22 and is secured to a casing 16 so as to be non-rotatable. The abutting faces of the valve plates have grooves 37, 38 connected to kidney-shaped ports which co-operate with the ports 32 in the plates 31. The pressurised areas of the port plates are such that a resultant pressure urges each cylinder block and port plate towards its corresponding face valve, the crowned splines 19, 21 permitting slight tilting to allow for manufacturing errors or wear. The housing 26 and valve plates 36 are urged towards the fixed valve plate 34 by fluid pressure acting on an annular piston 46 in a cylinder 47. Leakage from the circuit is replenished by a pump connected by check valves to the grooves 37, 38. In other embodiments, both swash plates may be rotatable and adjustable and the bores in one block 17 differ from those in the other block 18. port plate 31 co-operating with the cylinders in the assembly 17, 22 and is secured to a casing 16 so as to be non-rotatable. The abutting faces of the valve plates have grooves 37, 38 connected to kidney-shaped ports which co-operate with the ports 32 in the plates 31. The pressurised areas of the port plates are such that a resultant pressure urges each cylinder block and port plate towards its corresponding face valve, the crowned splines 19, 21 permitting slight tilting to allow for manufacturing errors or wear. The housing 26 and valve plates 36 are urged towards the fixed valve plate 34 by fluid pressure acting on an annular piston 46 in a cylinder 47. Leakage from the circuit is replenished by a pump connected by check valves to the grooves 37, 38. In other embodiments, both swash plates may be rotatable and adjustable and the bores in one block 17 differ from those in the other block 18.