AU642438B2 - Improved pilot operated valve - Google Patents

Description

642438 Form COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952-62 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE: Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority: Related Art: Class Int. Class Nameof Aplicnt:TO BE COMPLETED BY APPLICANT JAMES HARDIE IRRIGATION PTY LTD Addrass of Applicant: 53 Howards Street; Beverley, State of South Australia, Australia Actual Inventor: BOGDAN ROSZKOWSKI Address for Service: Care of R K MADDERN ASSOCIATES, 345 King William Street, Adelaide, South Australia, Australia Complete Specification for the Invention entitled, "IMPROVED PILOT OPERATED VALVE" The following statement Is a full description of this Invention, Including the best method of performing It known to me.us PATENT, TRAID MARKS DESICO44S SUB-OFFICE 9 N~OV 1990 SOUYTH- AUSTRALIA FU 'I2II1 2M 5185 This invention relates to improvements in pilot operated valves, and in particular to improvements in the design of such pilot operated valves.

Pilot operated valves are well known, where essentially water pressure is used to hold the valve closed. Such valves rely on a second parallel circuit across the valve closure member which can be opened or closed to release or apply the closing pressure on the valve.

Such pilot operated valves comprise an inlet chamber, an outlet chamber that is in fluid communication with the inlet chamber and a third chamber formed in the valve body and having an opening that is covered by a flexible diaphragm.

When the valve is closed, a closure member or seal on the diaphragm prevents flow between the inlet and outlet chambers by bearing against a seat. The seat is the opening between the inlet and outlet chambers. When closed, the third o" chamber is in fluid communication with the inlet chamber through a first conduit, and a second conduit, from the third chamber to the outlet chamber, is closed. The fluid conduit between the third chamber and the outlet chamber can be opened or closed by means of a solenoid actuated pilot valve.

"555*" The diaphragm normally has a valve closure member, such as a washer, and when the valve is assembled, the closure member can be brought to bear against the valve seat thereby closing the inlet chamber with respect to the outlet chamber.

Closure of the valve assembly is achieved when the solenoid is actuated to close the second conduit, thus restricting the free flow of fluid from the third chamber to the outlet chamber.

During closure of the valve, fluid pressure in the third chamber builds up as fluid enters it via the first conduit, thus the flexible diaphragm located between the third chamber and both the inlet and outlet chambers moves with the force of increasing pressure to overcome the aggregate force of the incoming fluid and the open to atmosphere outlet chamber pressure, thereby actuating the closure member to locate the valve seat to close the outlet chamber to the inlet chamber opening. A spring may be provided to aid the movement of the diaphragm and closure member towards the seat.

In order to open the valve, the solenoid valve is opened which causes a lowering of pressure in the third chamber, and as a result the pressure within the inlet chamber forces the closure member to raise thereby opening the valve.

To achieve correct operation of the valve, the water flow allowed through the first conduit must be much lower than the water flow allowed through the second conduit, such that a pressure difference is created between the third chamber and the inlet chamber which will allow the closure member to lift from the valve seat. This is achieved by having one or more small apertures within the diaphragm, and having much larger apertures and flow paths within the second conduit.

However, a major problem with this arrangement is that small holes used in the flexible diaphragm are readily blocked by debris, which will prevent the upper chamber from being pressurised, thereby preventing closure of the valve.

One solution to preventing such blockages, is to provide adequate levels of filtration, however in certain applications, this is either inconvenient or an added cost to the use of such valves. In addition, some filtration does not adequately prevent blockages from occurring.

a Therefore, it is an object of this invention to provide an improvement to pilot operated valves which overcomes the abovementioned problems.

It is a further object of this invention to provide a flow conduit between the inlet chamber and the outlet chamber which has a larger cross-sectional flow area, while maintaining the required flow restriction.

In its broadest form, the invention comprises a pilot operated valve having an inlet chamber, an outlet chamber in fluid communication with the inlet chamber, a seat forming an opening between the inlet and outlet chambers, a third chamber having an opening, a flexible diaphragm positioned across the opening of the third chamber having a closure member attached, the opening and diaphragm being positioned so as to enable the closure member to engage the seat, and close the inlet chamber with respect to the outlet chamber, by flexure of the diaphragm, a first conduit for fluid flow between the inlet chamber and the third chamber, a second conduit for fluid flow between the third chamber and the outlet chamber, a valve for opening and closing the second conduit, and a flow restriction means comprising a labyrinth style conduit associated with the first conduit which restricts the flow rate through the first conduit.

The essential requirement of the flow restricting duct is to provide as large as possible a cross-sectional area for fluid flow, while at the same time restricting the flow rate into the third chamber.

By providing the necessary flow restricting duct, minimum blockage will occur while at the same time providing ample flow restriction.

30 It is preferable that the flow restriction means be secured to the flexible diaphragm, and the flow restriction means may be attached to either side of the diaphragm.

Further, to prevent blockages occurring in the aperture through the diaphragm, a plurality of relatively large apertures may be provided. The flow restriction means may further comprise a chamber between the flow restricting means e 99@9i 9 9 9i.

*999 and the diaphragm so as to allow restricted flow through all of these apertures.

The flow restriction means may have any shape required, but preferably a toroidal shaped member which is positioned around the centre of a circular shaped flexible diaphragm is preferred. This enables the flow restriction means to be incorporated with the closure member which locates against the seat.

In order that the invention may be more readily understood, a preferred embodiment will now be described, but it will be realised that the scope of the invention is not to be confined or restricted to any of the features of this embodiment. This embodiment is illustrated in the accompanying diagrams in which:- 6@.

Fig 1 shows a cross-sectional view of the pilot operated valve, i Fig 2 shows a plan view of the flow restriction means, o and Fig 3 is a sectional view taken along the lines 3-3 of Fig 2.

O 0 In this embodiment, the pilot operated valve 10 has a main body portion 11 and a top portion 12. Formed within the main body portion is an inlet chamber 14 and an outlet chamber 15, openings 16 and 17 being provided for the inlet 25 and outlet chambers 14, 15 respectively.

000 0* The inlet chamber 14 is in fluid communication with the outlet chamber 15, and a seat 19 forms an opening between the inlet and outlet chambers 14 and A third chamber 20 is formed within the top portion 12, which has an opening having a diaphragm 21 located across the opening. The diaphragm 20 is secured in placed by being firmly clamped between the main body portion 11 and the top portion 12. The diaphragm 21 is manufactured from a resilient flexible material such as neoprene or silicon rubber.

A closure member and flow restriction means assembly 22 is secured in the centre of the generally circular diaphragm 21. The assembly 22 comprises a spigot plate 23 having a spigot 24 locating through a central aperture within the diaphragm 21.

A housing 25 is slidably located onto the spigot 24, and on one side has a chamber 26 for location of a flow restriction means 27 therein. On the other side, there is provided a recess for location of a rubber or synthetic rubber washer 28. The whole assembly is in turn held together by a collar 29 and threaded fastener 30. The collar 29 abuts against both the housing 25 and the washer 28 and effectively secures the diaphragm 21 between the spigot plate 23 and the housing The assembly 22 is located directly above the seat 19, and when the rubber washer 28 engages the seat 19, the diaphragm 21 is deformed from its normal rest position.

In order to assist location of the rubber washer 28 against the seat 19, the collar 29 has a chamfered surface 31 which assists in centrally locating the assembly 22 with respect to the seat 19.

S

As seen in g 1, there is provided a first conduit between the inlet chamber 14 and the third chamber 20. This conduit comprises a plurality of apertures 33 in both the spigot plate 23 and diaphragm 21.

In order to achieve fluid flow from the inlet chamber 14 ,o the third chamber 20, fluid first passes through a plurality of apertures 34 in the housing I5, and then flows into an inlet 36 of the flow restriction means 27. The fluid then exits from the flow restriction means 27 through an outlet 37 into a chamber 38. The chamber 38 is in fluid communication with the apertures 33, and thereby fluid then flows into the third chamber A second conduit for fluid flow between the third chamber 20 and the outlet chamber 15 is provided and comprises fluid conduit 39 and aperture 40. The opening and closing of the fluid conduit 39 is controlled by solenoid valve 41. The solenoid valve 41 is electrically operated, and a plunger 42 can be moved to engage a seat 43, thereby closing off the conduit 39.

In normal operation, when water pressure is applied to the inlet chamber 14, the valve can be opened by operating the solenoid valve 41 to lift the plunger 42 from the seat 43. This in turn allows fluid to flow from the third chamber 20 into the outlet chamber 15. As compensating fluid cannot flow from the inlet chamber 14 into the third chamber quickly enough, then the assembly 22 will lift from the seat 19. This thereby allows fluid flow from the inlet chamber to \:oP the outlet chamber 15. The degree of lifting of the assembly 22 can be controlled by positioning of the shaft 45. The shaft 45 is threadably engaged with the top portion 12.

In order to close the valve, the solenoid valve 41 is actuated so as to force the plunger 42 against the seat 43.

The fluid pressure within the third chamber 20 now equals the fluid pressure within the inlet chamber 14, and accordingly the spring 46 forces the diaphragm 21 and assembly 22 downwardly. The resulting pressure difference between the inlet chamber 14 and the outlet chamber 15 as the assembly 22 approaches the seat 19 causes the pilot valve 10 to rapidly close.

In the closed position, the pressure within the inlet chamber 14 equals the pressure within the third chamber and due to the pressure difference between these regions and the outlet chamber 15, the valve is held shut.

Obviously, in order for the pilot valve 10 to close, it is necessary that the first conduit allowing flow between the inlet chamber 14 and the third chamber 20 remain unblocked.

If this conduit were to become blocked, then the valve would not close.

Therefore, all of the apertures and flow paths associated with this conduit are of such cross-sectional area that a normal sized debris incorporated within fluid such as water for irrigation, will not cause significant blockage, As shown in Fig 2, the flow restriction means 27 comprises generally a toroidal ring. On one surface of the toroidal ring, there is provided a flow restricting duct 47 which in this eabdimnt. comprises a tortuous path or zig-zag channel, An inlet 36 is provided, and at the other end of the flow restricting duct, there is provided an outlet 37.

M 0 As the flow restricting means 27 is placed within the chamber 26 of the housing 25, the surface of the toroidal ring having the flow restricting duct 47 therein locates against the floor of the chamber 26, thereby closing off the flow restricting duct 47, As can be seen in Fig the side of the toroidal ring opposite to the flow restricting duct 47 comprises a chamber 38, and the aperture 37 connects the flow **00 restricting duct 47 with this chamber 38.

When the flow restricting means 27 is located within the chamber 26 of the housing 25, and the housing 25 is secured against the diaphragm 21, then the upper surfaces 49 of the flow restricting means 27 bear against the diaphragm 21, :I thereby forming a chamber between the flow restricting means 27 and the diaphragm 21.

Thus the assembly 22 provides both flow restriction means between the inlet chamber 14 and the third chamber as well as positioning the washer 28 for location against the seat 19.

7 r <i- It will be seen from the above description that the invention provides a unique and novel means of operating a pilot valve. The improvements described in this invention will enable such valves to be used with greater reliability through less blockages occurring. In addition, it will enable the use of such valves without the need for stringent filtering prior to entry of fluid into the valve.

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Claims (8)

1. A pilot operated valve comprising an inlet chamber, an outlet chamber in fluid communication with the inlet chamber, a seat forming an opening between the inlet and outlet chambers, a third chamber having an opening, a flexible diaphragm positioned across the opening of the third chamber having a closure member attached, the opening and diaphragm being positioned so as to enable the closure member to engage the seat, and close the inlet chamber with respect to the outi t chamber, by flexure of the diaphragm, a first conduit for fluid flow between the inlet chamber and the thiLrd chamber, a second conduit for fluid flow between the third chamber and the outlet chamber, a valve for open ng and closing the second conduit, and a flow restriction means comprising a labyrinth style co* .uit associated with the first conduit which restricts the flow rate through the first conduit.

2. A pilot operated valve according to claim 1 where the first conduit comprises an aperture through the flexible diaphragm, and said labyrinth style conduit is secured to the diaphragm.

3. A pilot operated valve according to claim 2, further comprising a chamber between the flow restricting means and ?0 the diaphragm, and a plurality of apertures through the flexible diaphragm, said flow restricting means, chamber and plurality of apertures comprising said first conduit.

4. A pilot operated valve according to claim 3 wherein the '3*S flow restricting means comprises a elongate member having a S labyrinth style conduit between an inlet and an outlet, said 0 E^nt? elongate member being spaced from the flexible diaphragm, said chamber being formed by walls extending between said elongate member and said diaphragm.

5. A pilot operated valve according to claim 4 wherein said labyrinth style conduit has a toroidal shape, with said walls comprising an inner circular wall and an outer circular wall.

6. A pilot operated valve according to claim 5 wherein the flow restricting means also comprises the closure member.

7. A pilot operated valve according to claim 5 further comprising a housing that is securable to the diaphragm, having on one side a closure member comprising a washer for sealing engagement with the seat, a cylindrical recess on the other side fo- location of the toroidal shaped flow restriction means therein, and a plurality of apertures in the housing to allow fluid flow to the flow restriction means, the housing being arranged to hold the flow restriction means against the diaphragm when the housing is secured to the diaphragm.

8. A pilot operated valve substantially as described hereinbefore and in accordance to and as illustrated in the accompanying drawings. Dated this 17th day of August 1993. SJAMES HARDIE IRRIGATION PTY LTD S* By its Patent Attorneys SR K MADDERN ASSOCIATES A e «e ll. I rV *V*OV