Patent GB-1038154-A (GB)
Title: Automatic controlling means for swash plate type pressure-fluid transmissi on gears
IPC: F04B49/00
Filed: 1963-06-04
Abstract: 1,038,154. Hydraulic transmissions. HONDA GIJITSU KENKUSHO KABUSHIKI KAISHA. June 4, 1963 [June 5, 1962], No. 22080/63. Headings F2C and F2D. A hydraulic transmission comprises a pump and a motor of the swash-plate type, one swashplate having a fixed inclination and the other being variable and biased by the associated pistons either due to the swash-plate trunnions being offset with respect to the transmission axis or by the associated cylinders which are open to the pressure side of the transmission differing in number from those open to the return side, the force on the swash-plate being balanced by a servomotor subject to spring and input-speed responsive fluid pressure. As shown in Figs. 1 and 2, a pump cylinder barrel 4 is splined on an input shaft 3 and urged by a spring 16 into contact with a part spherical surface 9A of a distributing plate 9 fast with a motor cylinder barrel 1 which is fast with an output gear 62. The pump has a fixed inclination swash-plate 6 mounted in the motor cylinder barrel by means of bearings 7, 8, and the motor has a variable inclination swashplate 12 mounted by bearings 13, 14 in a frame 11 which is pivotally mounted in a transmission casing F by trunnions C the axis of which is displaced by a distance #1 with respect to the input shaft 3 so that in operation the motor pistons 10 bias the swash-plate in a direction increasing the motor displacement. A servo piston 43 has a pivotal connection with the swash-plate frame 11 and is biased to the right by a spring 61 and to the left by input-speed responsive fluid pressure acting on the differential areas of the piston. The pressure is supplied by a gear pump 50 at a pressure determined by a centrifugal controlling device 52 driven by a prime mover E and supplied through lines 51, 49 to a cylinder chamber 48 and thence through a bore 47 to a cylinder chamber 46. A valve piston 54 is slidably mounted in the servo piston 43 and is actuated by a manually operable arm 56 which can shift the valve piston 54 to the right to open both chambers 46, 48 to exhaust through passages 57, 60, to shift the servo piston 43 to its right-hand position to increase the motor displacement to its maximum amount. In operation, with the valve piston 54 in its left-hand position, the swash-plate mechanism 11 is moved to a position in which the forces on it balance, thereafter an increase in load increases the pressure in the pressure side of the transmission so that the swash-plate is moved to a position increasing the motor displacement, whereas an increase in the speed of the prime mover increases the pressure in the servomotor which shifts the swash-plate to reduce the motor displacement. The pump pistons during their working stroke displace liquid through a port 18 in the distributer plate 9 and a passage 20 to a space 28 which is bounded by a sleeve 25 which is in sealing engagement with the rear surface 9B of the distributer plate, and thence liquid passes through passages 30-32 to the motor cylinders to give the motor pistons their working stroke, liquid being discharged on the return stroke of the pistons through the passages 32-30 to a chamber 29 and thence through passages 33 and a port 19 to the pump cylinders for the intake stroke of the pump pistons. A rotary valve 38 is provided whereby the pressure and return chambers 28, 29 may be interconnected to provide a neutral position. Fig. 5 shows a modification of the transmission in which instead of having the motor swashplate offset, the valve sleeve 25 is offset a distance #2 from the transmission axis so that the number of pistons communicating with the pressure side of the transmission is different from the number communicating with the return side. As an alternative the motor swash-plate may be fixed and the pump swash-plate be variable.