Valve

Abstract

A directional control valve has three ports with a first fluid path extending between the first and second ports and a second fluid path between the second and third ports. A chamber is defined at an intersection of the first and second fluid paths and contains a spherical valve ( 16 ) member disposed between opposed, spaced valve seats ( 19,20 ). The valve member is movable across the chamber between the valve seats between an open position in which the valve member is displaced from a first valve seat so that the first fluid path is open and is sealed against a second valve seat so that the second fluid path is closed and a closed position in which the valve member is sealed against the first valve seat so that the first fluid path is closed and displaced from the second valve seat so that the second fluid path is open. The valve member is biased towards the closed position by opposed first and second biasing members ( 34, 41 ) of unequal loading. An actuator ( 32 ) such as, for example, a solenoid is operable to move the valve member from the closed position to the open position against the unequal loading.

1 . A directional control valve comprising:
 a housing defining first, second and third ports;   a first fluid path between the first and second ports and a second fluid path between the second and third ports;   a chamber defined at an intersection of the first and second fluid paths;   a substantially spherical valve member disposed between opposed, spaced valve seats in the chamber; the valve member being movable across the chamber between the valve seats between an open position in which the valve member is displaced from a first valve seat so that the first fluid path is open and is sealed against a second valve seat so that the second fluid path is closed and a closed position in which the valve member is sealed against the first valve seat so that the first fluid path is closed and displaced from the second valve seat so that the second fluid path is open; the valve member being biased towards the closed position by opposed first and second biasing members of unequal loading; and   an actuator for moving the valve member from the closed position to the open position.   
     
     
         2 . A directional control valve according to  claim 1 , further comprising a first actuating pin arranged coaxially with the first valve seat for moving the valve member to the open position, the first actuating pin being acted on by the first biasing member and the actuator. 
     
     
         3 . A directional control valve according to  claim 2 , wherein the valve member is movable towards the first valve seat by means of a second actuating pin arranged coaxially with the second valve seat on an opposite side of the valve member to the first actuating pin, the second pin being acted on by the second biasing member. 
     
     
         4 . A directional control valve according to  claim 3 , wherein the first and second actuating pins are coaxially aligned. 
     
     
         5 . A directional control valve according to  claim 3 , where the valve seats are defined by valve elements received in the housing, the valve elements each having a central bore for receipt of one of the first or second actuating pins. 
     
     
         6 . A directional control valve according to  claim 5 , wherein the first and second actuating pins are slidable in the central bore in dynamic seals. 
     
     
         7 . A directional control valve according to  claim 5 , wherein the first fluid path includes at least one passage extending from an outer surface of a first valve element to the central bore and the second fluid path includes at least one passage extending from an outer surface of a second valve element to the central bore. 
     
     
         8 . A directional control valve according to  claim 7 , wherein there are a plurality of passages in each of the first and second valve elements, the outer surface of the first and second valve elements having a recess that provides fluid communication between the plurality of passages. 
     
     
         9 . A directional control valve according to  claim 1 , further comprising a spacer for maintaining the first and second valve seats at a predetermined distance apart, the spacer defining part of the first and second fluid paths permitting fluid communication between the second port and the chamber. 
     
     
         10 . A directional control valve according to  claim 9 , wherein the spacer is an annular member with a plurality of substantially radially extending ports therethrough. 
     
     
         11 . A directional control valve according to  claim 9 , wherein the spacer has a peripheral recess to allow for the flow of fluid around its periphery. 
     
     
         12 . A directional control valve according to  claim 1 , wherein the first and second biasing members are springs. 
     
     
         13 . A directional control valve according to  claim 1 , wherein the actuator is a solenoid. 
     
     
         14 . A directional control valve according to  claim 12 , wherein there is provided at least one adjuster for adjusting the degree of compression of the first or second spring so as to adjust the biasing spring force. 
     
     
         15 . A directional control valve according to  claim 4 , where the valve seats are defined by valve elements received in the housing, the valve elements each having a central bore for receipt of one of the first or second actuating pins. 
     
     
         16 . A directional control valve according to  claim 6 , wherein the first fluid path includes at least one passage extending from an outer surface of a first valve element to the central bore and the second fluid path includes at least one passage extending from an outer surface of a second valve element to the central bore. 
     
     
         17 . A directional control valve according to  claim 10 , wherein the spacer has a peripheral recess to allow for the flow of fluid around its periphery. 
     
     
         18 . A directional control valve according to  claim 3 , wherein the actuating pins are slidable in first and second bores, the actuating pins having a diameter that is substantially equal to the diameter of the first and second bores. 
     
     
         19 . A directional control valve according to  claim 18 , wherein the first and second valve seats are defined around ends of the first and second bores. 
     
     
         20 . A directional control valve according to  claim 18 , wherein the is provided a radial clearance between ends of the first and second actuating pins nearest the first and second valve seats and the respective surfaces defining the first and second bores. 
     
     
         21 . A directional control valve according to  claim 3 , wherein the first and second pins are elongate.