GB850466A - Improvements in or relating to piston valves - Google Patents

Abstract

850,466. Valves. CARLS, W. April 8, 1957 [April 9, 1956], No. 11415/57. Class 135. An aluminium housing 40, Fig. 2, which encloses a solenoid S is formed with a bore 50 having ports 52, 54, 56, 58 and 60 which lead into passages 62, 64, 66, 68 and 70 respectively; a further bore port 61 is provided. Within the bore 50 is a fully floating sleeve 72 incorporating peripheral grooves that correspond with the bore ports, which grooves open to the sleeve interior; between each groove is a synthetic rubber " O "-ring. Endwise sleeve float is limited by a ring 78 and a plug 80 with an atmospheric opening 82 whilst the all-round clearance between the sleeve and housing enables expansion and contraction to take place without distortion of the sleeve. Within the sleeve is a spool having lands 84, 88 and urged to the right by a spring 94; the spool is moved leftwardly upon energizing the solenoid S, the armature of which is provided with stops 97 or 78. The sleeve 72 and spool are made of a corrosion-resistant high-carbon steel which is then hardened, ground, bored and lapped to a micro-finish. A plurality of valves V, Fig. 1, are bolted upon a manifold M embodying two through exhaust passages 18, 22 and one through supply passage 20; passages 18, 20 and 22 open into the housing passages 68, 70 and 62, Fig. 2, respectively, of each valve whilst housing passages 64, 66 lead into manifold passages 24 and 26, each pair of which is connected to a cylinder 98. Any given valve station may be closed by a plate 10, Fig. 1, having a plug 23 therein that provides a tapping leading, e.g. to auxiliary controls. Since the solenoid housing is supported independently of the manifold, the solenoid may be reached without disturbing the valve assembly; the valve may be serviced without removing it from the manifold. In a modification, the spool is urged rightwardly by air pressure, e.g. from a pump, instead of the spring. In another modification, the end lands of the spool are provided with " O "-rings and grooved for lubrication purposes; the valve is suitable for use in hydraulic systems. In a further modification, the spool end lands are lengthened to enable the valve to be used with two separate supplies which may be at different pressures; the exhaust is taken from a single central port and each end port is connected to a separate supply source. In a still further modification, the spool is actuated by air pressure and returned by a spring. In another modification, the valve may be used in a system employing a vacuum and positive pressures for respectively picking up and releasing metal plates by means of a vacuum cup. The spool is biased by a long spring on a pin, and with the spool in the rightward position the " work lift port is open to both " tank " and " vacuum ports. In the leftward position of the spool shown in dotted lines, the " work lift " port is connected to a " pressure " port. Each end of the valve is open to atmosphere as is the pressure port during the time the work lift " port is connected to the " tank and " vacuum " ports.