Patent GB-940472-A (GB)
Title: Improvements in and relating to a transmission mechanism constituting a speed variator
IPC: F04C14/18
Filed: 1962-02-27
Abstract: 940,472. Hydraulic transmission of power. J. J. VALDENAIRE. Feb. 27, 1962 [Feb. 28, 1961], No. 7571/62. Heading F2C. [Also in Division F1] A transmission mechanism for converting a constant input torque and speed into variable output torque and speed comprises a pump P, Fig. 1, and a motor T having rotors Rp, Rt rigid with a driving shaft 1 and driven shaft 2, respectively, and disposed so that the pump discharges into and draws directly from the motor, a stator S common to the pump and motor, the rotor at least of the pump and the stator being capable of undergoing a relative movement of translation, and an elastically-yieldable device 45, Fig. 4, for automatically varying, in opposition to the action of the pressure created in the motor, the relative positions of the stator and the rotor and consequently the relative volumes of the pump and motor as a function of the resistant torque so that when said torque increases, the effective volume of the pump decreases. The pump and motor rotors Rp, Rt are rotatable relative to each other by means of a bearing 25 and each rotor has vanes 20, 33 slidably disposed in slots arranged in radial or secant planes, the vanes being located longitudinally by walls 17, 30 having ports 18, 31 connecting the chambers between the vanes with chambers I, IV at the ends of the stator. The stator has an inner circumference 34 which is eccentric by a distance e from the axis of the rotors to provide crescent-shaped chambers for the pump and motor. The eccentricity, together with tubes 40 secured to an end wall 5 of the mechanism, prevents the stator rotating and springs 45 urge the stator axially to the left of Fig. 1. Rings 52, 53 are rotatably mounted in the stator and permit the vanes to slide radially in the crescent-shaped chambers II, III while maintaining the chambers sealed from the end chambers I, IV. The lower portions of the crescent-shaped chambers are separated by a partition 60 having an aperture 61, and passages 72 lead from the lower portions to the chambers I, IV. The upper portions of the crescent-shaped chambers are connected by passages 66 in the stator and a port 68 to a reservoir 69 at atmospheric pressure. When the driving shaft 1 is rotated, the vanes 20 of the pump are urged by centrifugal force into contact with the surface 34 of the stator to form chambers g, h, i, j, Fig. 7, which draw fluid from the longitudinallyaligned chambers of the motor, the fluid in the pump chambers being at atmospheric pressure; the outward movement of the vanes by the centrifugal force may be resisted by springs to provide a clutch effect at low speeds. When chamber j moves to the position k, and subsequently l, m, and n, the decrease in volume of the chambers creates high pressure in the fluid which acts on the blades 33 of the motor to rotate the motor rotor and shaft 2 in the opposite direction. The atmospheric pressure in chamber j of the pump and the high pressure in chamber k of the motor are joined by the aperture 61 and the passage 72 and act in the end chambers I, IV on the ends of the stator, the areas of the ends being equal except for the tubes 40 so that an unbalanced force acts on the end of the stator in chamber I against the pressure of the springs 45. As the resistance on the shaft 2 varies, the high pressure, and hence the unbalanced force in the chamber I varies and the springs 45 move the stator to vary the volumes of the pump and motor chambers, an increase in resistance on shaft 2 causing the volume of the pump chamber to decrease and that of the motor chamber to increase. In an alternative embodiment, the stator S, Figs. 9 and 10, is fixed and variation of the volume of the pump chambers is effected by moving the pump rotor 107 which is rotated by gearing 115, 116 from a driving shaft 100. The pump rotor has vanes 128 mounted on pivots 131 in the rotor and on pivots 134 in shoes 133 guided in annular recesses 135 in side plates 136 of the stator. The side plates also have annular recesses 163 for the shoes of pivots 162 for the vanes 157 mounted on pivots 160 in the motor rotor Rt. Extending between the walls of the stator are stator ports 141 . . . 144, and holes 146, 147 between adjacent pairs of the parts communicate by way of ports 150 with an annular space 168 to act on the lower surfaces of bearing blocks 113 for permitting vertical movement of the pump rotor, recess 127 permitting the pressure in space 168 to act also on the upper surfaces of the bearing blocks. The areas on each side of the bearing blocks are equal except for the area occupied by tubes 123 having members 120 engaged by springs 122 acting on the rotor of the pump. The stator ports 141 . . . 144 divide the space between the pump and motor rotors into high pressure and low pressure spaces 149, 148, the latter space being connected to a reservoir 174 by passages 172, 173. In operation, when the pump rotor is rotated in the direction of the arrow f3, low pressure between two pump vanes 127 from the chamber 148 is discharged through the port 147 and high pressure between two motor vanes 175 from the chamber 149 is discharged through the port 146 so that the average of the two pressures acts in the space 168 and on the upper and lower surfaces of the bearings 113, the unbalance caused by the rods 123 being balanced by the springs 122. As the resistance on the driven shaft 101 varies, the high pressure in chamber 149 varies resulting in a variation in pressure acting on the bearing blocks which is balanced by the springs moving the pump rotor to a new position. An air pocket 171 absorbs any slight difference in the volumes of fluid communicating with one another through the ports 146, 147. Instead of moving vertically in a straight line, the movement of the pump rotor may be along an arc having its centre coincident with the axis of shaft 100, and the position of the pump and motor rotors may be reversed. A clutch effect may be produced by the provision of a needle valve adapted to progressively close a passage between the high and low pressure chambers.