GB354327A - - Google Patents

Abstract

354,327. Hydraulic servomotors. MELCZER, T. DE, 8, Budafoki Ut, Budapest, and UHER ENGINEERING CO., Ltd., Glarus, Switzerland. Feb. 4, 1930, No. 3802. Convention date, Feb. 4, 1929. [Class 69 (ii).] Relates to an hydraulic steering apparatus in which a piston is employed comprising two symmetrical piston members rigidly connected with one another, one working in each half of a cylinder so as to form two separate working spaces, the piston and a valve controlling the supply and exhaust of fluid being loosely coupled'together mechanically so that in case of failure of the fluid supply the piston can be moved directly by the valve. Three forms of the invention are described. According to one form of the invention the cylinder 1, Fig. 1, is divided by a partition 9 and the piston 7 has two heads working one in each half of the cylinder so as to form two working spaces 29, 30 one on each side of the partition, the controlling valve 11 working in conjunction with ports 14 in the piston to admit pressure fluid from an inlet pipe 5 to either one of the working spaces as required and to exhaust it from the other. The valve is actuated by hand by means of a worm sector 23 and arm 18, and the piston is connected to the members to be steered by means of a rocker arm 26. Fluid is exhausted from the working spaces past the heads of the valve, and through openings 15, 16 in the piston heads to a box 2 and an outlet pipe 17. If the pressure fails movement of the valve in either direction brings one of the valve heads against a projection 31 on the corresponding piston head and the piston is moved positively in the desired direction. The valve is preferably formed without lap but a small amount of lap may be provided, to prevent leakage of oil. When the valve is moved in either direction pressure fluid is admitted to one of the working spaces and the piston is moved in the same direction as the valve until it overtakes the valve and closes the supply passage. In the arrangement shown in Fig. 4, the hydraulic apparatus is arranged in parallel with an ordinary steering gear 22, 23, the valve being actuated by a cam 32 on the steering shaft 21, link 33 and arm 18, while the piston-operated arm 26 is connected by a link 33<1> to the rocker segment 23 which actuates the ordinary steering linkage 27. According to the second form of the invention working spaces 29, 30, Fig. 5, are formed between the outer faces of the symmetrical piston heads 7 and the ends of the cylinder 36, the controlling valve 11 being adapted to admit pressure fluid into either of the working spaces and to exhaust it from the other into the space 38 situated within the peripheral wall of the cylinder between the two piston heads, this space being always open to low-pressure by communication with the fluid outlet 17. Pressure fluid is admitted by the inlet pipe 5 and passes through a bore 42 and ports 43 to the interior space 44 of the valve 11. When the valve is moved in either direction fluid is admitted through ports 14 in one or other piston head to the corresponding working space 29 or 30, the piston is moved in the same direction, and fluid is exhausted from the other working space through the ports 14 to the space 28 surrounding the valve, this space being always in communication through passages 47 with the low-pressure space 38. In this construction the steering-shaft 21 reciprocates the valve through screw-and-nut gear 34 and the piston rotates the rocker shaft 25 of the steering gear by means of an arm 24. The nut is prevented from rotation by its lost-motion connection with the piston, this connection comprising a stud 39 working in a slot in the piston, while the piston is prevented from rotation by a key or ridge 41 engaging a circular groove 40 in the shaft 25. In the third form of the invention the apparatus, Figs. 6 and 7, is of the semi-rotary type, the cylinder being divided into four working spaces 29, 29<1>, 30, 30<1> by two fixed abutments 9 and two piston members or vanes 7, the vanes being made without any ports or passages therethrough, and the valve 11 being adapted to admit pressure fluid into either pair of diametrically opposite working spaces as required and to exhaust it from the other pair, the action being such that any shock to the road wheels or the like tending to rotate the piston members would force fluid back into the inlet pipe thereby preventing any sudden shock from being transmitted to the cylinder abutments. The vanes or piston heads 7 are rigidly connected together by a barrel 8 having ports 14 therein. Pressure fluid is admitted by the pipe 5 to the interior of the valve and can pass through holes 49, spaces 28 and the ports 14 to the working spaces, being exhausted therefrom through valve passages 51, 52 to a chamber 2 and the outlet pipe 17. The valve is rocked by means of the worm sector 23, and the piston is fixed on a shaft 55 carrying the arm 26 operating the steering wheels, the lost-motion connection between the valve and piston being formed by stops 56 on the piston adapted to engage abutments on the sector 23 fixed to the valve. The right-hand bearing of the shaft is lubricated bv oil contained in a lowpressure chamber 53 connected by a pipe 54 with the chamber 2.