Multi-way directional fluid flow control valve arrangement

Abstract

In order to provide a multi-way directional fluid flow control valve arrangement which provides good control while being relatively cheap to manufacture, I use simple main valves all of which have parallel axes and all lie in a common plane, enabling me to form the main valves in a cheap manufacturing operation; the pilot valve however is more complex and has at least four connections, but because the pilot valve is smaller, this extra complexity does not make the whole valve arrangement more expensive.

Description

This invention relates to a multi-way directional fluid flow control valve arrangement controlled by a pilot valve. Where hereinafter a valve is characterised by the number of connections, the total number of inlet and outlet connections is meant. For instance, if a valve has two inlet connections and four outlet connections, the valve is characterised as a six-connection valve. The directional control valve arrangement is primarily envisaged as a pneumatic valve, but it may be used for controlling for instance hydraulic fluids.

One use of such a directional control valve arrangement is in the control of a double-acting pressure-fluid-operated ram. Each ram chamber in the ram will normally have a respective line connecting it to the valve arrangement, the valve arrangement in turn being connected to a supply line and also to an exhaust line. The valve arrangement may have two positions, each connecting a respective one of the ram chambers to supply and the other ram chamber to exhaust, and the valve arrangement may in addition have a closed centre position. Normally, such a valve arrangement is provided by having a complex main valve, say a spool valve or complex arrangement of mechanically interlinked poppet valves, and a simple pilot valve controlling the position of the main valve.

The present invention provides a multi-way directional fluid flow control valve arrangement including a pilot valve with at least four connections and at least two open/shut main valves each controlled by the pilot valve, the main valves preferably having parallel axes and the main valves preferably all lying in a common plane.

In this manner, the earlier arrangement referred to above is reversed, and the main valve can be simple while the pilot valve and its connections to the main valve are move complex, transferring the complexity to the inherently cheaper, low duty pilot valve. This can be useful for all bore sizes of the main valve, but the advantages become more marked as the bore sizes increase, say for bore sizes of 12.5 mm and upwards. The arrangement can be incorporated in a single compact and simple assembly, for instance because the main valves can have parallel axes and lie in a common plane. Furthermore, with such an arrangement of the main valves, the housing containing the main valves can be made in a simple moulding operation, without any necessity for drilling out ports or ducts after moulding.

The pilot valve can have a very small effective bore size, say 1.5 mm diameter.

The pilot valve is preferably a spool valve, and most preferably is a "hard spool, hard sleeve" spool valve; i.e., a spool valve having no soft seals (such as O-rings); such spool valves can be very sensitive (requiring small forces and displacement for actuation) and be balanced (no bias from pressure of fluid).

The spool valve would include a valve sleeve and an axially movable spool, and the valve sleeve may have bores therethrough extending generally parallel to the axis of the valve sleeve, leading to flow connections on one or both of the axial end faces of the valve sleeve, the valve sleeve also having radial bores leading to valve ports adjacent the spool, an outer sleeve being fitted over the valve sleeve to close the radially outer ends of the radial bores or to connect such radially outer ends to further bores. Stainless steel may be used for both the valve sleeve and the spool, though other materials such as aluminium may be used. The radially outer ends of the bores may lead into channels, for instance annular channels, around the outside of the valve sleeve, and any one radial bore could be supplemented by at least one further radial bore in the same transverse plane, to increase the flow cross-section through the valve.

The valve sleeve need not be of circular cross-section; it could be say of square cross-section, particularly if the valve sleeve is made of aluminium.

The pilot valve has at least four connections, a supply connection, two control connections and an exhaust connection for controlling each of two groups of main valves; the pilot valve could have five or six connections, say with two separate supply connections and/or two separate exhaust connections. The pilot valve is preferably a 469-12, 9-11, the valves have an inlet 71, and outlet 72, an annular seat 74 (FIGS. 10l 10a & 11), a bias spring 75 and a pilot duct 76.

In FIG. 9, instead of an annular seat, the valve has a transverse sill 77 into which a diaphragm 73 closes.

FIGS. 10a (closed) and 10b (open) show a loosely fitting piston-type valve member 78 with an additional top seat 79 to prevent continuous leakage after the valve has opened. In this way, a perfect seal is obtained even though the valve member 78 is somewhat loose in its bore.

FIG. 11 (closed) shows a valve member 80 with a uni-directional seal in the form of a flexible lip 81 which is applicable to two-position operation. During actuation (downwards movement of the valve member 80) pressure is substantially equalised on either side of the lip 81.

FIGS. 12a and 12b (closed) shows two alternatives. In FIG. 12a, there is a fitting piston 82; In FIG. 12b, there is a flexible lipped seal 83 on a piston 84. The flexible lipped seal 83 would not cause excessive frictional resistance to the movement of the valve element because the pressure differential across it could be quite small when movement is taking place. These alternatives are particularly suitable for high pressure hydraulic applications. The alternatives of FIGS. 12a and 12b could have top seats as in FIGS. 10a and 10b.

The valve of FIGS. 13 to 16 is arranged for control by a four-connection pilot valve which may be generally of the type shown in FIG. 1, but which may not be incorporated in the valve block. For instance, the pilot valve may be mounted on top of the valve block 101 with an actuator mounted on top of the pilot valve.

The valve block 101 forms a single housing for four open/shut main valves 102, and is in two parts 103, 104 sandwiching a single generally rectangular diaphragm 105.

As can be seen in FIG. 16, each main valve has a loop-shaped valve seat 106 in a valve chamber 107 of a similar shape, the shape being that of a rectangle with semi-circular ends. In this manner, the "length" of the valve chamber is substantially greater than the "width."

There are two tapped connections 108 (see FIGS. 13 and 14) for connection to the controlling pilot valve, the tapped connection 108 communicating with the main valve by way of suitable ducts 109 in the upper part 103 of the housing.

Some of the main ports of the valve intercommunicate as can be seen in FIG. 13, and a sub-plate can be mounted on the bottom of the block (generally similar to the sub-plate of the embodiment of FIGS. 2 to 8) in order to provide four connections for the main valve combination.

Claims

1. A multi-way directional fluid flow control valve arrangement for the directional control of a fluid power actuator, the arrangement comprising:

a single, pressure-balanced spool-type pilot valve having at least a supply connection, an exhaust connection and two control connections and having two opposite end positions;

a housing containing at least four pilot-controlled open/shut main valves, each main valve having an inlet, an outlet, a pilot connection, a valve port and an axially movable valve member which seats on the valve port to close the valve at one end of the travel of the movable valve member, the movable valve members of all the main valves having parallel axes of movement and all main valves lying in a common plane; at least one pressure inlet for connection to a source of pressure fluid, at least one exhaust outlet and at least two working connections for connection to the fluid power actuator;

main duct means connecting the at least one pressure inlet to the inlets of a first and a second of the main valves, connecting the at least one exhaust outlet to the outlets of a third and a fourth of the main valves, and connecting the at least two working connections respectively to the outlet of the first main valve and the inlet of the third main valve and to the outlet of the second main valve and the inlet of the fourth main valve; and

pilot duct means connecting said control connections of the pilot valve to respective said pilot connections of the main valves, whereby the first and fourth main valves are open and the second and third main valves are shut at one end position of the pilot valve and the first and fourth main valves are shut and the second and third main valves are open at the other end position of the pilot valve.

2. A control valve arrangement as claimed in claim 1, wherein the pilot valve is a "hard spool, hard sleeve" spool valve.

3. A multi-way directional fluid flow control valve arrangement comprising a pilot spool valve having at least a supply connection, an exhaust connection and two control connections, a valve sleeve, an axially movable spool therein and an outer sleeve fitted over the valve sleeve, the valve sleeve defining bores therethrough extending generally parallel to the axis of the valve sleeve, the valve sleeve having flow connections on at least one axial end face thereof in communication with said bores, the valve sleeve defining radial bores in communication with the first-mentioned said bores, leading to valve ports adjacent said spool, and the outer sleeve being imperforate at least adjacent the radially outer ends of said radial bores; at least four pilot-controlled open-shut main valves, each main valve having a pilot connection, a valve port and an axially movable valve member which seats on the valve port to close the valve at one end of the travel of the movable valve member, the movable valve members of all the main valves having parallel axes of movement and all main valves lying in a common plane; and

duct means connecting said control connection of the pilot valve to respective said pilot connections of the main valves.

4. A control valve arrangement as claimed in claim 3 wherein the outer sleeve closes the radially outer ends of said radial bores.

5. A control valve arrangement as claimed in claim 1, wherein the pilot valve comprises a valve body and a movable valve member therein, the movable valve member having said two opposite end positions, the pilot valve moving through an intermediate position as it moves from one end position to the other end position, in which said intermediate position all said main valves are closed.

6. A control valve arrangement as claimed in claim 1, and comprising pilot exhaust duct means communicating said pilot valve exhaust connection with a said exhaust outlet.

7. A control valve arrangement as claimed in claim 1, wherein each of said main valves is a diaphragm valve comprising an axially movable diaphragm and said housing comprises at least two parts which are joined generally in a plane normal to the axes of the main valves, said arrangement further comprising a sheet of resilient material secured between said parts to provide the diaphragms of the main valves.

8. A control valve arrangement as claimed in claim 1, wherein each said main valve is a diaphragm valve comprising a valve chamber, a valve seat, and an axially movable valve member in the valve chamber and seatable on said valve seat, said movable valve member comprising a diaphragm, the valve chamber being substantially longer than it is wide, as seen in section normal to the axis of movement of said movable valve member, and said main valves being in line with the shorter dimensions of the valve chambers extending along the axis of said line.

9. A multi-way directional fluid flow control valve arrangement comprising:

a pilot spool valve having at least a supply connection, an exhaust connection and two control connections;

at least four pilot-controlled open/shut main diaphragm valves, each of said main diaphragm valves comprising a valve chamber, a pilot connection, a valve seat and an axially movable valve member in the valve chamber and seatable on said valve seat to close the valve at one end of the travel of the movable valve member; said movable valve member comprising a diaphragm and the movable valve members of all the main valves having parallel axes of movement and all main valves lying in a common plane; said valve chamber being substantially longer than it is wide, as seen in section normal to the axis of movement of said movable valve member;

wherein each said valve seat is in the form of a closed loop, the valve chamber having an inside wall of rectangular shape with semi-circular ends, as seen in section normal to the axis of movement of said movable valve member, and the spacing between the closed loop valve seat and said inside wall of the valve chamber, as soon in section normal to the axis of movement of said movable valve member, being constant all the way around the valve seat; and

duct means connecting said control connections of the pilot valve to respective said pilot connections of the main valves.

10. A control valve arrangement as claimed in claim 1, wherein said four main valves and said pilot valve having parallel axes, the axes of said four main valves being at the corners of a square and said pilot valve having its axis at the intersection of the diagonals of said square.

11. A control valve arrangement as claimed in claim 1, wherein said movable valve member of each said main valve comprises a diaphragm, said arrangement defining a backing surface and said diaphragm being adjacent said backing surface

when said main valve is open. 12. A multi-way directional fluid flow control valve arrangement comprising:

a pilot spool valve having at least a supply connection, an exhaust connection and two control connections;

at least four pilot-controlled open/shut main valves, each main valve having a pilot connection, a valve port and an axially movable valve member which seats on the valve port to close the valve at one end of the travel of the movable valve member, the movable valve members of all the main valves having parallel axes of movement and all main valves lying in a common plane;

duct means connecting said control connections of the pilot valve to respective said pilot connections of the main valves;

said control valve arrangement controlling a double acting ram comprising two pressure chambers, in which arrangement said four main valves provide a supply valve and an exhaust valve for each ram chamber, and wherein said pilot valve has a midposition in which said pilot valve supply connection is in communication with said pilot valve control connections, to apply fluid pressure to all four main valves to close them, the valve arrangement comprising an inlet for connection to a supply of pressure fluid, an exhaust and a working connection for each ram chamber, and said arrangement further comprising a check valve associated with said inlet for preventing back flow of fluid out of said inlet, direct connections between each said working connection and said inlet, and respective check valves in said direct connections preventing direct flow of fluid from said inlet to said working connections.

13. A control valve arrangement as claimed in claim 1, and further comprising an electromagnetic moving-armature actuator including means defining a space and an armature movable in said space, said pilot valve including a valve body defining a space and a movable valve member movable in said space, the former said space being sealed to the latter said space.

14. A control valve arrangement as claimed in claim 1, and having a single said pressure inlet, a single said exhaust outlet and two said working connections.

15. A control valve arrangement as claimed in claim 1, wherein in each main valve, the valve port forms the outlet of the valve, a valve seat surrounds the outlet and the inlet is outside the valve seat.

16. A control valve arrangement as claimed in claim 2, wherein the pilot valve comprises a radially thick sleeve defining therein a small diameter, cylindrical bore with no lands, and defining radial ducts leading into the bore and providing pilot valve ports for said pilot valve supply, exhaust and control connections.

17. A control valve arrangement as claimed in claim 1, wherein said housing also houses the pilot valve, wherein the pilot valve is a separable unit comprising a valve body and a valve spool therein, wherein the axis of movement of the valve spool is parallel to the axes of movements of the main valves, and wherein the pilot valve body has one axial end face sealed to said housing, all said pilot duct means passing through said end face.

18. A control valve arrangement as claimed in claim 1, wherein the pilot valve is a separable unit comprising a valve body and a valve spool therein, and wherein the valve body has one face sealed to said housing, all said pilot duct means passing through said one face.

19. A control valve arrangement as claimed in claim 18, wherein the axis of movement of the pilot valve spool is parallel to the axes of movement of the main valves, said one face of the pilot valve body being an axis end face.

20. A control valve arrangement as claimed in claim 7, wherein each of said housing parts is moulded in plastics material, said main duct means being moulded into at least one said part on that side of the resilient sheet which is remote from the pilot valve and respectively portions of said pilot duct means being moulded into a said part on the other side of the resilient sheet.

21. A control valve arrangement as claimed in claim 16, wherein an outer sleeve is fitted over said radially thick sleeve, said radially thick sleeve defines longitudinal ducts therethrough extending generally parallel to the axis of the pilot valve, said radially thick sleeve has flow connections on at least one axial end face thereof in communication with said longitudinal ducts, said radial ducts are in communication with said longitudinal ducts, and the other sleeve is imperforate at least adjacent the radially outer ends of said radial ducts.

22. A multi-way directional fluid flow control valve arrangement comprising:

a "hard spool, hard sleeve" pilot valve having at least a supply connection, an exhaust connection and two control connections, the pilot valve comprising a radially thick sleeve defining therein a small diameter, cylindrical bore with no lands, and defining radial ducts leading into the bore and providing pilot valve ports for said supply, exhaust and control connections;

at least four pilot-controlled open/shut main valves, each main valve having a pilot connection, a valve port and an axially movable valve member which seats on the valve port to close the valve at one end of the travel of the movable valve member, the movable valve members of all the main valves having parallel axes of movement and all main valves lying in a common plane; and

duct means connecting said control connections of the pilot valve to respective said pilot connections of the main valves.

23. A multi-way directional fluid flow control valve assembly for the directional control of a fluid power actuator which comprises:

a first molded housing formed with a pilot valve cavity and with four cavities, each cavity constituting a first diaphragm valve portion, said housing having an end wall defining said diaphragm valve cavity and including a plurality of orifices formed therein, said orifices including a supply orifice, an exhaust orifice and control diaphragm valve orifice in fluid flow communication with said first diaphragm valve portion;

a second molded housing formed with four cavities, each cavity constituting a second diaphragm valve portion, said housing being formed with fluid supply conduit means in fluid communication with two of said second diaphragm valve portions, said housing being formed with fluid exhaust conduit means in fluid communication with the remaining two of said second diaphragm valve portions, said housing being formed with fluid control conduit means in fluid communication with said fluid supply conduit means and said fluid exhaust conduit means;

valve seating means positioned between said first diaphragm valve portion and said second diaphragm valve portion thereby forming a diaphragm valve;

a pressure balanced spool-type valve disposed in said pilot valve cavity of said first molded housing and comprised of a spool of hard metal and a sleeve of hard metal, said spool being formed with a supply conduit means, an exhaust conduit means, and a plurality of conduit means in fluid flow communication with said diaphragm valve control orifices, said conduit means being in alignment with the respective orifices formed in said end wall of said first housing; and

means for mounting said first housing to said second housing.

24. The fluid flow control valve as defined in claim 23 wherein said four cavities lie on a common plane.

25. The fluid flow control valve as defined in claim 24 wherein said valve seating means are mounted on a resilient sheet member disposed between said first and second housing to form a gasket.

26. The fluid flow control valve as defined in claim 23 wherein said housings are formed of a plastic material.

27. The fluid flow control valve as defined in claim 23 wherein each of said four cavities of said second molded housing is formed with a valve port whereby axial movement of said valve seating means closes said valve port.

28. The fluid flow control valve as defined in claim 27 wherein each of said cavities of said first molded housing is defused by a frusto-conically shaped end wall.

29. The fluid flow control valve as defined in claim 28 wherein a spring is positioned within each of said cavities of said first molded housing.

30. The fluid flow control valve as defined in claim 23 wherein said flow conduit means of said sleeve are formed with bores extending generally parallel to the axis thereof and with radially extending bores in fluid communication with said bores extending generally parallel to the axis of said spool, and further including a sleeve positioned about said spool to close said radially extending bores.

31. The fluid flow control valve as defined in claim 30 wherein said spool is provided with a land having a thickness approximately the same as said radially extending bores.

32. The fluid flow control valve as defined in claim 23 wherein said spool moves within said sleeve between two operative end positions and wherein said spool at an intermediate position between said end position closes each of said diaphragm valves. 33. The fluid flow control valve as defined in claim 31 wherein in one end position one of said plurality of conduit means of said spool are in fluid communication with one of said two of said second diaphragm valve portions and with one of said remaining two of said second diaphragm valve portions, and wherein in the other end position the remaining conduit means of said plurality of conduit means of said spool are in fluid communication with the other one of said two of said second diaphragm valve portions and with the remaining one of said remaining two of said second diaphragm valve portions.

34. The fluid flow control valve as defined in claim 23 wherein said exhaust orifice in said end wall of said first injection molded housing is in fluid communication with said fluid exhaust conduit means formed in said second injection molded housing.

35. The fluid flow control valve as defined in claim 23 wherein each of said cavities in said second housing is formed by a cylindrically-shaped outer wall and a cylindrically-shaped inner wall, said cylindrically-shaped inner wall forming a valve chamber, said chamber being substantially longer than the width thereof.

36. The fluid flow control valve as defined in claim 23 wherein the axis of said spool-type valve is parallel to the axis of said diaphragm valves.

37. The fluid flow control valve as defined in claim 23 wherein said housings are square-shaped and said diaphragm valve portions are formed at the corners thereof.

38. The fluid flow control valve as defined in claim 37 wherein the axis of said spool-type valve is at the intersection of diagonals of said housings.

39. The fluid flow control valve as defined in claim 23 wherein said spool and sleeve are in metal-to-metal fluid sealing engagement.