Patent GB-481093-A (GB)
Title: Improvements in driving means for motor vehicles
IPC: B60K17/10
Filed: 1937-03-02
Abstract: 481,093. Hydraulic driving-gear for motor vehicles ; pumps. W.A.S.P. ENGINEERING CO., Ltd., and ASPDEN, E. W. March 2, 1937, No. 609/36. [Classes 79 (ii) and 79 (v)] [Also in Groups XXVIII and XXIX] In motor vehicle hydraulic transmission of the kind in which the vehicle engine B, Fig. 2, drives a liquid-controlled master motor or pump D supplying liquid to independent motors E mounted on and driving each road wheel, the controlling liquid which governs the stroke of the master motor or pump is supplied to the master motor by a pump H through a valve H<1> controlled by a governor H<2> driven by the engine B to vary the stroke of the master motor thereby varying the supply of liquid to the wheel motors E to give an automatic variable gear. In the construction shown the master pump D is connected by a suction pipe g to a tank G and delivers liquid through a pipe d to a valve-box F containing a freewheel and non-return valve K, a reversing valve L, and a brake valve M. The reversing valve L is connected by alternative pipes e<1>, e<2> to the wheel motors E. The pump D comprises radial cylinders 1, Figs. 3 and-4, bolted to the engine flywheel C and containing plungers 2 having gudgeon pins 3 engaging guides 4a in a casing 4 rotating with the cylinder and flywheel on bearings 4b in a non-rotary but slidable casing 5. A lug 11 on the casing 5 engages a slot 12 in a stationary gear housing 10 so that the casing 5 can be moved from the position shown, in which the casing 4 is concen'tric with the flywheel C and a stationary shaft 9, to positions in .which the casing 4 is eccentric to the flywheel. In the concentric position shown the stroke of the plungers 2 is nil, but as the casings 4 and 5 are moved from this position the plungers move with an increasing stroke Ports at the inner ends of the cylinders 1 communicate alternately with suction and delivery ports 16, 18 formed in the shaft 9 and respectively connected to the pipes g, d. The casing 5 is moved to vary the pump stroke by means of pistons 13 working in cylinders 7, 8 which are formed ion the housing 10 and are connected by pipes 7a, 8a, to the casing of the slide valve H<1> of the controlling pump H, Fig. 17. This pump may be driven by the engine cam shaft b, as shown, or by an electric motor, and the valve H<1> is controlled by an engnie-driven centrifugal governor H<2>. through a rod 22, 23. The governor spring 25 is adjustable 'by means of a screw sleeve 26, and the time-lag of the valve H<1> may be regulated by means of an eccentric 29 acting through an arm 28 to adjust a spring 30 on the rod 23. When the engine is running idly the valve H<1> is in the position shown in Fig. 17 and liquid is supplied through the pipe 8a to cylinder 8, Fig. 4, to reduce the stroke of the master pump to zero. If the engine speed is increased the valve H<1> is raised, admits pressure liquid through pipe 7a to cylinder 7 and connects cylinder 8 to exhaust pipe 33, so that the casings 4, 5 are moved to an eccentric position and the master pump D drives the wheel motors E in the direction determined by the reversing valve L. When the vehicle is in motion the stroke of the master pump D is automatically varied by the governor H<2>, in accordance with the engine speed, .the stroke being reduced whenever an increase in the load causes the engine to slow down, and the stroke being inereased when the engine speed increses. When the load and the engine speed are constant the governor H2 keeps the valve H<1> in its central position in which both pipes 7a, 8a are closed and the liquid is locked in both cylinders 13 so that the casing 5 is held fast in its last adjusted position. The reversing' valve L, Figs. 12 and 13, comprises a rotary plug l with vertically-spaced bores l<1> inter-connecting the pipes d, g<1>, e<1>, e<2>. The free-wheel and non-return valve K, Fig. 16, provides a byepass between the delivery and return pipes d, g<1>, and comprises two flap valves k, k<1>. The non-return valve k prevents return flow through the pipe d back to the master pump D, so that the vehicle can be stopped on an incline without any tendency for it to run back. The freewheel valve k<1> allows the wheel motors E to run freely when the vehicle is in motion and the master pump D is in the ' no-stroke ' condition as a result of allowing the engine to run idly ; in this case the wheel motors circulate the liquid idly through the pipes el, e<2>, valvebox L and valve k<1>. The brake valve M, Fig. 15, comprises a plunger m connected to the ordinary brake pedal (not shown) and adapted to close more or less the return pipe g<1>. When the accelerator pedal is released, so that the wheel motors act as pumps, and the. ordinary brake pedal is depressed the plunger m will throttle the passage g<1> and thus brake the wheel motors. Each wheel motor, Figs. 7 and 8, comprises a crankshaft 43, 40 fixed to the road wheel which rotates on bearings 41 in a stationary drum 42 carrying radial cylinders 47, preferably six in number. The pistons 46 are connected by rods 45 to a disc 44 mounted on the crank-pin. Oil is supplied to and from the motor by the pipes e<1>, e2 communicating with annular grooves 48, 49, distribution being effected by piston or sleeve valves 51 and ports 50.