AU709936B2

AU709936B2 - Shut-off valves

Info

Publication number: AU709936B2
Application number: AU75413/96A
Authority: AU
Inventors: Frank Stuart Curnow
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-12-19
Filing date: 1996-12-18
Publication date: 1999-09-09
Anticipated expiration: 2016-12-18
Also published as: AU7541396A

Description

P:\OPER\RSH\PN8273.SPE- 17/12/96 -2- SHUT-OFF VALVES The present invention relates to shut-off valves and more particularly but not exclusively to shut-off valves for incorporation into the fuel system of a vehicle powered by liquid petroleum gas (LPG).

It is a requirement that LPG fuel systems for vehicles include a secondary shut-off valve installed between the outlet of a fuel storage tank shut-off valve and a converter. Shutoff valves may also be incorporated directly at the outlet of the LPG storage tank and the inlet of the converter. In systems which permit the possibility of selection between LPG and petrol, a shut-off valve is also fitted downstream of the fuel pump.

Previously proposed shut-off valves comprise a valve piston having an end face which engages against a raised valve seat at the outlet side of the valve. The inlet side of the valve is open to the LPG flow or the outlet of the fuel pump whereby the pressure of the fuel acts on the piston to force the piston into sealing engagement with the valve seat to thereby close the valve at the outlet side. The valve is opened by energisation of a solenoid which draws the valve piston away from the valve seat against the inlet pressure of the fuel. In these prior valves, the sealing face at the end of the piston is formed by a sealing disc mounted within the body of the piston, the sealing disc abutting on the raised valve seat in order to form the seal. Although this provides an effective seal, the fabrication of the piston with the sealing disc mounted within the body of the piston is relatively expensive.

According to the present invention, there is provided a shut-off valve for fuel under pressure, said valve comprising a valve chamber, a valve piston within the valve chamber, a valve inlet arranged for communication with a source of fuel under pressure such that the ooo*• pressure of fuel applied to the inlet enters the valve chamber and forces the valve piston into engagement with an outlet port which communicates the valve chamber with a valve outlet whereby to close the outlet port and block communication between the valve inlet and valve outlet, and power-operated means for drawing the valve piston away from the outlet port :\OPERXRSH\PN8273.SPE 17/12/96 -3whereby to open the outlet port, wherein said valve piston comprises an end face adjacent the port, said end face including a projecting spigot carrying an O-ring seal which seals within a valve seat surrounding the port.

In preferred embodiments of the invention, the valve may be used either as a secondary shut-off valve in an LPG system or as a shut-off valve at the outlet of a storage tank for LPG or as a shut-off valve for the gas converter in an LPG system. A valve in accordance with the invention can also be constructed for use in a fuel system which can switch between LPG and petrol.

Advantageously, the valve piston is formed from solid rod material, with the end face and spigot being formed by machining the rod.

Advantageously, the power-actuated means comprises a solenoid winding surrounding the valve chamber, although it is possible that an alternative arrangement could be used to achieve a similar effect whereby the valve piston is moved away from the outlet port upon energisation.

Embodiments of the invention will now be described, by way of example only, with ooooi S 20 reference to the accompanying drawings, in which: :.:':Figure 1 is a schematic section of a shut-off valve for installation as a secondary shutoff valve for LPG; Figure 2 is a view illustrating schematically the end wall of a valve chamber of the valve of Figure 1 and showing an inlet orifice and outlet port; Figure 3 is a fragmentary enlarged view showing schematically the sealing end portion of a valve piston of the valve of Figures 1 and 2 and its co-operation with the outlet port; Figure 4 is a section similar to Figure 1 but showing a shut-off valve constructed for installation downstream of a fuel pump; and Figure 5 is a schematic cross-section of a modified form of the valve of in-line construction.

P:\OPER\RSH\PN8273.SPE- 17/12/96 -4- With reference to Figures 1 to 3 of the accompanying drawings, a shut-off valve for incorporation as a secondary shut-off valve upstream of a converter comprises a valve body 2 having an inlet 4 which mates with a corresponding fitting on a line leading from the shutoff valve on the storage tank. An inlet passage 6 leads via an orifice 8 into a cylindrical valve chamber 10 which houses a valve piston 12. The valve chamber 10 is within the winding of a control solenoid 14. The inlet orifice 8 to the cylindrical valve chamber 10 is defined at a side of an end wall 16 of the valve chamber 10. An outlet port 18 from the valve chamber is also defined in the end wall 16, in a central part thereof. The outlet port 18 leads to an outlet passage 20 in the valve body 2. It will be noted from Figure 1 that the inlet and outlet of the valve body are substantially co-axial and the axis of the valve chamber 10 and piston 12 is substantially at right angles to that axis.

A suitable fuel filter is incorporated within the inlet passage 6. As shown, the filter is in the form of a disc 22 composed of a sintered alloy, for example bronze, although other forms of filter may alternatively be incorporated.

With reference to Figure 3, a valve seat 24 is defined in the end wall 16 around the outlet port 18. Unlike the prior shut-off valves earlier described, the valve seat 24 is not 2raised from the end wall 16 but instead is recessed within the end wall 16 and this recess can ooo i be formed simply by drilling. The adjacent end of the valve piston 12 is principally of solid construction, with an O-ring seal 26 being mounted on a short spigot 28 which projects from the end face of the piston 12. The spigot 28 is integral with the body of the piston 12 and can be produced in a simple machining operation which forms the end face, with the spigot 28 projecting from the end face. The spigot 28 is formed with an annular groove which retains the O-ring 26 and, likewise, this groove is simply formed by a machining operation. The entire piston 12 can be fabricated from solid rod of ferromagnetic material.

In operation, pressurised fuel from the fuel tank enters the valve chamber 10 via the inlet orifice 8 and, due to the differential areas of the sealing end face of the piston and opposite end face of the valve piston, exerts a force on the valve piston in a direction towards P:\OPER\RSH\PN8273.SPE 17/12/96 the end wall 10 whereby the O-ring seal 26 is held in tight sealing engagement with the valve seat 24. This action is also aided by a compression spring 30 which biases the valve piston 12 towards the end wall 10. Energisation of the solenoid 14 causes the valve piston 12 to retract from the end wall 16 so as to open the outlet port 18 to thereby permit fluid flow from the inlet orifice 8 through the outlet port 18 and thence into the outlet passage The use of an O-ring seal on a short projecting spigot machined from the end face of the valve piston provides a significant simplification in the manufacture of the valve piston in relation to valve pistons for prior shut-off valves, thus resulting in a cost reduction. Also, the O-ring seal can readily be replaced in a much simpler procedure than would be necessary to replace the sealing disc of the prior valves.

Although the embodiment of Figures 1 to 3 has been described in relation to a secondary shut-off valve, a valve of substantially identical construction can also be used as the shut-off valve for incorporation at the outlet of the LPG storage tank. In this case, the inlet 4 of the valve body will mate with a corresponding outlet fitting on the storage tank.

Likewise, a valve of substantially identical construction can be used as the shut-off valve for incorporation at the inlet of the gas converter of the LPG system, the inlet 4 of the valve body being sized to mate with the inlet fitting on the converter.

S In Figure 4 there is shown a shut-off valve for mounting downstream of a fuel pump in a system which has the facility to switch between LPG fuel supply and petrol. The valve shown in Figure 4 is essentially of the same construction as that shown in Figures 1 and 3 except that the inlet orifice 8 and outlet port 18 are of a larger cross-sectional area which is needed to handle the required flow of petrol from the fuel pump.

Figure 5 shows a valve in which the cylindrical valve chamber 10 is in line with the inlet passage 6 and outlet passage 20 and is directly interposed between the inlet and outlet passages. In this embodiment, fuel enters the valve chamber 10 directly from the inlet passage 6, with the fuel passing through an axial bore 40, and transverse bore 42 in the piston P:\OPER\RSH\PN8273.SPE. 17/12/96 -6- 12 and then around the piston 12. The valve piston 12 closes an outlet port 44 in an end wall 46 which separates the valve chamber 10 from the outlet passage 20 at the end of the valve chamber 10 remote from the inlet passage 6. However in other respects the operation of the valve is as discussed in relation to the previous embodiments of the invention. Similarly, the end of the valve piston 12 carries an O-ring 26 formed on a short projecting spigot and which seats within a recess formed around the outlet port 44 in the end wall 46. The valve may be used as the shut-off valve on an LPG storage tank or as a secondary shut-off valve.

The embodiments have been described by way of example only and modifications are possible within the scope of the invention.

to t* p:\OPER\RSH\PN8273.SPE 17/12/96 -7- THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:- 1. A shut-off valve for fuel under pressure, said valve comprising a valve chamber, a valve piston within the valve chamber, a valve inlet arranged for communication with a source of fuel under pressure such that the pressure of fuel applied to the inlet enters the valve chamber and forces the valve piston into engagement with an outlet port which communicates the valve chamber with a valve outlet whereby to close the outlet port and block communication between the valve inlet and valve outlet, and power-operated means for drawing the valve piston away from the outlet port whereby to open the outlet port, wherein said valve piston comprises an end face adjacent the port, said end face including a projecting spigot carrying an O-ring seal which seals within a valve seat surrounding the port.

2. A valve according to claim 1, wherein the valve piston is formed from solid rod material, with the end face and spigot being formed by machining the rod.

3. A valve according to claim 1 or claim 2, wherein the spigot is formed with an annular groove in which the O-ring is retained.

4. A valve according to claim 3, wherein the groove is formed by machining the spigot.

A valve according to any one of claims 1 to 3, wherein the valve seat is recessed !'"'"within a wall of a body of the valve and is formed by drilling.

6. A valve according to any one of claims 1 to 5, wherein the valve inlet and valve outlet are in substantial alignment along a first axis, and the valve piston is movable within the valve chamber along a second axis orientated substantially at right angles to the first axis.

7. A valve according to any one of claims 1 to 5, wherein the valve inlet and outlet are in substantial alignment along a first axis, and the valve piston is movable within the valve chamber along said first axis, said valve chamber being directly interposed between the inlet

Claims

8. A valve according to any one of claims 1 to 7, wherein the valve is for use with LPG.
9. A valve according to claim 8, wherein the valve is for use as a shut-off valve for an LPG storage tank, a shut-off valve for a gas converter, or as a secondary shut-off valve. petrol. A valve according to any one of claims 1 to 7, wherein the valve is for use with
11. A shut-off valve substantially as hereinbefore described with reference to the accompanying drawings. DATED this 18th day of December, 1996. FRANK STUART CURNOW By his Patent Attorneys: DAVIES COLLISON CAVE 9.* ABSTRACT A shut-off valve particularly for a fuel system of an internal combustion engine powered by LPG comprises a valve piston formed from solid rod having at one end face a projecting spigot carrying an 0-ring seal which seats within a recessed valve seat formed within the body of the valve. .00. 6060 of 9** 9 9 P:\OPRR\RSH\PN82?3.SPE 17/12/96