GB1053463A - - Google Patents

Abstract

1,053,463. Hydrostatic transmissions. BORG-WARNER CORPORATION. July 7, 1964 [July 23, 1963], No. 27959/64. Headings F2C and F2K. In an infinitely variable hydrostatic transmission, for small cars, comprising two groups of axially aligned cylinders 15, 16 in integral cylinder blocks 10, 11, brazed at 47 fast with an input (or output) shaft 12, within which two groups of pistons 17, and 18, forming units A and B, are disposed and connected to slippers 24 which bear respectively on a variable swashplate 19, pivotally mounted in a case 14, and a fixed angle swash-plate 20 integral with the output (or input), shaft 40, the pistons are connected to the slippers by cylindrical heads 21, on the pistons, engaging cylindrical bores 25 in the slippers and retained by circlips, the resulting single axis joints keeping all the pistons oriented in the same direction whereby the pistons are held rotationally stationary on their own axis such that they rotate once relative the cylinder blocks per revolution thereof, the pistons and cylinders having intercommunicating parts controlling low and high fluid pressure circuits between the units A and B, either of which may serve as the motor or pump dependent on the direction of input drive. In operation, advancing the swashplate 19 from the neutral position (Fig. 1) towards the vertical position, with the input shaft 12 rotating, builds up pressure in the system, pressure fluid being discharged from the B unit, forming the pump, through piston ports 68, high pressure cylinder ports 65, centre chamber 46, cylinder and piston ports 64, 68, into the A unit cylinder, forming the motor, from which it is throttled by the piston ports 68 through low pressure cylinder ports 66 into passages 56 and returned to the pump B. Reverse is effected by tilting the swash-plate 19 farther away from vertical from the neutral position shown. In neutral, an inwardly spring-loaded centrifugal valve 49 remains open at low R.P.M. permitting the fluid to circulate freely between the centre chamber 46 and outer passages 56 by way of passages 57-60. Ports 61 and 63 interconnect the chamber 46 and also passages 56 with a fluid pressure source (not shown) via a passage 62 in the input shaft 12. The pistons are formed with ported recesses 71, 72 to equalize fluid pressure around the pistons in their cylinders and the slippers 24 are recessed at 34 to provide floating bearings on fluid supplied through piston and slipper passages 32, 33.