Patent GB-1189207-A (GB)
Title: Improvements in or relating to Hydraulic Rotary Positive-Displacement Units of the Internally-Meshing Gear Type
IPC: B62D5/097
Filed: 1967-07-18
Abstract: 1,189,207. Power-assisted telemotor steering-systems. TRW Inc. 18 July, 1967 [4 April, 1967], No. 32923/67. Heading B7H. [Also in Division F1] In an hydraulic steering-system for a road vehicle a unit 10 contains a rotary positive-displacement machine of the gerotor type and a control valve-member coupled to a steering wheel 33 so as to regulate the flow of hydraulic fluid e.g. oil, between a pump and reservoir 11, 12 and a piston-and-cylinder unit 16 coupled to the steering mechanism. The machine aforesaid includes a rotor 67 fixed to a rotatable tubular-sleeve 38 coupled by a torsional shaft 32 to the wheel 33, the rotor meshing with a corresponding ring 63 that can revolve in a planetary manner under the control of teeth 72, 73 in response to rotor rotation. Ports 77, 79 for the fluid are controlled by the ring 63. The valve member includes an axially-movable rotary sleeve 100 having annular lands and coupled to the sleeve 38 by splines 42 and to a rotary sleeve 50 by a pin 110 slidably engaging with a helical groove (112), Fig. 6 (not shown), in the sleeve 50. Mutually-overlapping portions 43, 51 of the sleeves 38, 50 permit limited angular displacement of one sleeve relative to the other to effect axial movement of the sleeve 100 due to the action of the pin 110. The sleeve 50 is coupled to the steering wheel at its external end. Annular recesses 92, 93, 94, 96, 98 in a static housing 29 are controlled by the lands on the sleeve 100, the recesses 94 and 96, 97 being hydraulically connected to the reservoir 12 and pump 11, respectively, and the recesses 92, 93 being connected to opposite ends of the cylinder 18. Further annular recesses 88, 91 are hydraulically connected (as shown) to the ports 77, 79, which are in a rotatable plate 74 fixed to the sleeve 38. When the steering wheel is in its neutral position the sleeve 100 is situated as shown (Fig. 2) so that the working spaces between the rotor 67 and the ring 63 are isolated from the rest of the hydraulic system; and when torque is applied to the steering wheel in either direction the rotor is initially locked hydraulically and, due to the torsional capability of the shaft 32, the sleeve 50 shifts the sleeve 100 axially, Fig. 5 (not shown), to permit flow of fluid to and from the unit 16 by way of said working spaces until the rotor restores the sleeve 100 to its former position and thereby terminates the operation of said unit. Manual steering can be effected by means of the unit 10 in the event of pump failure, the rotary positive-displacement machine acting as a pump, which is driven by the steering wheel. The teeth 72, 73 may be replaced by a plurality of axially-orientated cylindrical pins (116), Figs. 9 to 11 (not shown), which are attached to the ring (meshing with the rotor) and slidingly engaging with cylindrical recesses in a static cover-member (24a), the ring being thereby rendered capable of orbital motion only. Alternatively, the teeth are retained the beforementioned cylindrical recesses in an annular disc (123), Figs. 12 and 14 (not shown), which is fixed to a shaft (32b) replacing the shaft 32, the rotor and the valve plate being fixed to a tubular sleeve or bearing (120) that is rotatable about the shaft (32b) to permit planetary motion of the ring.