GB1488711A - Hydraulic valve - Google Patents

Abstract

1488711 Hydraulic reciprocating motors NIHON SPINDLE SEIZO KK 24 Sept 1974 [26 Sept 1973 12 Nov 1973 26 Dec 1973] 41535/74 Heading F1A [Also in Divisions B3 and B4] A valve, Fig. 5, for supplying oil alternately to a pair of outlet passages 2, 2', e.g. for driving a piston and cylinder type vibrator (20), comprises a spool 5 reciprocable in a housing 37, 37', 14, the reciprocations being automatically induced by the supply of pressurized oil to an inlet passage 1 in the housing and by the abutment of the spool against stoppers S. The spool 5 is mounted with clearance in a bore 4 and supported in bearings 6, 6'. Spool lands 9, 10, 10' are arranged to connect the inlet passage 1 to one of the outlet passages 2 or 2' while connecting the other outlet passage to exhaust via a port 3 or 3'. Alternative porting configurations are described, Figs. 5A and 7 (not shown). The stoppers S comprise resilient blocks or spring-loaded members 40, Fig. 5, which are axially adjustable manually or by automatic mechanical or hydraulic means to determine the frequency and centre of spool reciprocation. The hydraulic means shown comprise hydraulically actuated pistons 33. The axial adjustments result in changes in the frequency of the alternating flow and the proportions of oil delivered to the outlet passages 2, 2'. In Fig. 6 the valve B supplies liquid to cylinder chambers 49, 49' to cause a cylinder 44 to reciprocate over a piston 43. The cylinder 44 applies shock to e.g. a rock crushing tool or a pile gripped by jaws 78, the latter being carried by a casing 61 within which the cylinder 44 reciprocates. In order to vibrate the cylinder 44 equally about the piston 43, sensing ports 48, 48' and exhaust ports 51, 51' uncovered by the cylinder 44 in the event of cylinder deviation are provided. When during starting the cylinder is in its lowermost position, sensing port 48' communicates through the cylinder chamber 49 with exhaust port 51', whereby initially only the chamber 49 can be pressurized. Thus the cylinder is restored to its mid vibration position, any subsequent deviation resulting in pressurization of one or other of the sensing ports 48, 48'. Pressurization of a sensing port acts via a passage 36 or 36' on the piston 33 of the appropriate stopper S to alter the flow proportions to the passages 2, 2'. Further embodiments are described, Figs. 8-13 (not shown) in which the valve acts as a pilot valve to control a similarly constructed main valve, the latter valve having opposed pressure chambers for receiving the alternating supply and outlet passages for connection to the vibrator. In these embodiments the stopper S of the main and/or pilot valves are adjustable.