Patent GB-389856-A (GB)
Title: Improvements in or relating to control means for variable speed power transmission mechanisms
IPC: F16H37/08
Filed: 1931-09-25
Abstract: 389,856. Controlling variable-speed gearing; thermally - actuated valves. HAYES, F. A., Middletown Township, New Jersey, U.S.A. Sept. 25, 1931, No. 26794. Convention date, Oct. 9, 1930. [Class 80 (ii).] In control mechanism for variable-speed gearing actuated by oil delivered at a rate depending on the speed of the driving motor, means are provided to render the action unaffected by the varying viscosity of the oil due to changes in temperature. A byepass valve 72, Fig. 3, is controlled by a thermostat helix 75. The invention is described as applied to the precessional friction driving-gear for vehicles shown in Figs. 1, 5, and 6 of Specification 254,341, [Class 80 (ii), Gearing, Variablespeed &c.]. A driving-shaft 10, Fig. 1, carries end toric discs 12, 26 having a loose double disc 14 between them. The disc 14 is driven oppositely at the same speed by non-epicyclic rollers 18 clamped parallel to the gear axis. A driven shaft 11 with a frame 33 carrying planetary rollers 29, 30 is thus not driven when the rollers 29, 30 are also parallel. A speed change is initiated to drive forward by lowering roller 30, Fig. 2, and raising roller 29. Precession or spiralling of the rollers then takes place until there is again equilibrium with the axes of the rollers intersecting the gear axis. There are limit stops at 45, 46. Such a change-up in speed is effected automatically in consequence of increased speed of the engine sending more oil along ducts F, F<1> above a diaphragm 39 and below a diaphragm 40. This oil is drawn from a sump in a casing 25, Fig. 1, by a pump 53 on the shaft 10 and sent along a pipe 61, Fig. 3, where it is deflected by a valve 67 and passage 68b to the ducts F, F<1>. The valve 67 is shown in its mid-position with the car stopped. To start the car, the control valve 67 is moved to the left by a control handle 65 to open the passage 68b and ducts F, Fl to the pressure oil. It may be necessary to speed up the engine to produce sufficient oil pressure to precess the rollers 29, 30 sufficiently to overcome the load at starting. Ducts R, R<1> lead from below diaphragm 39 and from above diaphragm 40, and this turning of the valve connects the ducts R, R<1> through a valve passage 68a to a drain pipe 62 leading to the sump. Turning the valve 67 to the right reverses the car by tilting the rollers 29, 30 the other way from the parallel position. According to this invention, thermal effects are compensated by the thermostatic valve 72, Fig. 3, inserted in a byepass 71 through which oil constantly circulates to the drain 62, thereby affecting the oil pressure at the control valve 67. The valve 72 comprises a sleeve with ports 73, Fig. 4, which turns inside a fixed barrel 70 with ports 74. A bimetallic spiral 75, Fig. 3, around which the oil circulates is connected at one end to the valve sleeve 72 and at the other to an adjusting screw 76. Rough and fine adjustments of the whole device are effected by a screwdriver at 76 and by a tangent screw 79. Wastage oil passing through the opening 73, 74 adjusted to suit its viscosity enters a chamber 69 which is separated from the drain 62 by a hand valve 80. The engine speed necessary to develop pressure to precess the rollers to the highest speed depends on (a) the amount of oil wasted in the byepass and (b) the resistance of the load tending to slow down the engine. When the thermostatic valve is closed, less is wasted, more is delivered to the diaphragm chambers, and a lower engine speed will maintain the necessary pressure. With the hand valve 80 closed, a low engine speed can keep the rollers in the highest speed position. The hand valve 80 thus gives the operator easy control of the whole mechanism within the limits imposed by the setting of the thermostatic valve. A ball valve 85 leading directly to waste is for safety.