NZ203542A - Lift-type fluid-flow charge valve - Google Patents

Description

203 5 4 2 Priority Date(s): PtofCb. AQfe? Complete Specification Filed: U.*,v3 Class: .Tr.l£>K3J.l3%$ Publication Date: . ....ft.?.H4Y. 1986.... I P.O. Journal, No: . )323 N.Z.No.

NEW ZEALAND Patents Act 3953 COMPLETE SPECIFICATION "FLUID-FLOW CHARGE VALVE." We, NEW ZEALAND INDUSTRIAL GASES LIMITED, a New Zealand company of Hutt Park Road, Lower Hutt, New Zealand do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement : - i* *7 f'iARl985 V<V V,v C p f « // 2 035 4 2 This invention relates to the charging of receiver vessels, with a fluid at a selected pressure, from a fluid source at a pressure equal to or greater than the selected pressure.

The receiver vessel may be a pneumatic tyre, an ciccumulator, a gas storage cylinder and so on. The source may be any known source such as the receiver of a gas compressor or the like.

Charging, as referred to above, is usually performed by use of a pressure regulator. Such regulators have a feed orifice to set a limit to the maximum flow rate required, and this orifice, ideally, closes when the selected vessel pressure is readied.

The existing pressure regulators have been effective up to a point. Nevertheless, they are open to objection in several respects. For example, they rarely halt fluid flow precisely when the selected vessel pressure is reached; and, as the charging process approaches its finish, as the charging and vessel pressures approach equality, the charge rate slows down correspondingly.

The object of this invention is to overcome, or at least ameliorate, the disabilities referred to above, by the provision of a charge valve which causes the charge rate to be substantially constant, and which abruptly closes when the selected vessel pressure is reached.

The invention provides a charge valve comprising: a cylinder having, at one end, an upstream inlet for infeed of charging fluid and, at its other end, a downstream outlet for departure of said fluid, 203542 a piston in said cylinder "having an upstream portion able to close said inlet and a downstream portion able to close said outlet, resilient loading means whereby said piston is constantly urged to close said inlet, and a supply duct by which said one end is in communication with said other end.

Examples of the invention are shown in the drawings herewith. Fig. 1 is a schematic showing of a valve in medial cross-section; and Fig. 2 substantially repeats Fig. 1 except for showing of a minor modification.

Referring to Fig. 1 a valve body comprises a cylinder composed of two mating sections 3 and 5 which screw together in fluid-tight manner. Axially of the body is a chamber divided into an upstream portion 6 and a downstream portion 7. Body portion 3 has an axial bore 3 for the supply of fluid to chamber portion 6. In portion 6 a resilient valve sea': 10 encircles trie end of bore 3. A piston 12 is located within chamber 6,7, and is free to move axially under fluid pressure. The piston separates the chamber into fluid inlet end 6 and fluid outlet end 7. An 'O' ring seal 13 prevents fluid by-passing the piston. At chamber downstream portion 7 a compression spring 14 locates between the piston 12 and the end wall of chamber 7. An adjustment screw 15 threads in body portion 5, so that its central bore 16 aligns with conical portion 17 of piston 12. A nut 18 which screws into body portion 5 may be used to lock adjustment screw 15 in the desired location to form a flow passage between the piston 12 and the bore 16 of adjustment screw 15. Piston 12, at its * £03542 fluid inlet end, has a valve facing 19, which when piston 12 is pushed toward fluid inlet 0, contacts seat 10. A bleed duct 20 extends from the inlet end face of piston 12 to an end orifice 21 which opens to the fluid outlet end of piston 12.

In operation of the valve, fluid is admitted to chamber portion 6 by way of inlet 8. If this inlet pressure is greater than the loading due to spring 14, piston 12 will be forced away from seat 10 and cone 17 will shut off the 10 upstream end (22) of passage 16. The fluid which then enters chamber 6, travels through bleed duct 20 and bleed orifice 21, and enters chamber portion 7 to increase pressure in that portion. Thus, the fluid pressure in portion 7 rises and combined with the force of spring 14, tends to push piston 12 back towards the inlet end of the valve, and the piston conical end 17 is moved away from the end (22) of flow passage 16. Fluid thus flows through passage 16 to charge the receiver vessel to which the charging valve is attached. The flow of fluid into bore 16 (through its inlet opening 22) 20 exactly matches the flow of fluid from orifice 21 since any difference in these two flows would cause the pressure in chamber portion 7 to change thereby causing piston 12 to move and alter the effective area of opening 22 to correct the error. For example, if the flow through opening 22 is greater than the flow through orifice 21 the chamber portion 7 receives less flow-in than flow-out, hence its pressure decreases. This results in a decrease in the force applied to the outlet end of piston 12 so that the piston is pushed r) toward passage opening 22 thereby decreasing the out-flow 2 0~5 j 4 2 until the pressures again reach equilibrium.

The condition of constant flow, remains substantially unchanged throughout the charging process regardless of increase in back pressure from the receiver vessel. As this back pressure increases piston 12 is forced further away from flow passage 22 to increase the flow area through this passage to compensate for the increase in back pressure.

It will be appreciated that the valve arrangement as described with reference to the drawing is given purely by way of example. That example may be changed extensively without departure from the essence of the invention. For example, (See Fig. 2) the duct 20, 21 (of Fig. 1) instead of being formed in piston 12 could be formed in the casing as indicated by duct 23 in valve section 3, duct 24 in valve section 5 and the annular channels 25 formed in their meeting end faces. 2 03542

Claims (4)

WHAT WE CLAIM IS: Tim OBftlllG nDPI!1Img ftlliii IHTVUnrPIOiT Aflul PiO rOLLOWC: -

1. A charge valva comprising: a cylinder having, at one end, an upstream inlet for infeed of charging fluid and, at its other end, a downstream outlet for departure of said fluid, a piston in said cylinder having an upstream portion able to close said inlet and a downstream portion able to close said outlet, resilient loading means whereby said piston is constantly urged to close said inlet, and a supply duct by which said one end is in communication with said other end.

2. A valve according to claim .1 wherein said supply duct is formed wholly within said piston.

3. A valve according to claim 1 wherein said supply duct is formed wholly within said cylinder.

4. A charge valve substantially as herein described with reference to Fig. 1 or Fig. 2 of the drawings herewith. T -t rv r> NEW ZEALAND INDUSTRIAL GASES LIMITED By Their Attorneys HENR-* " ~ LIMITED By: 4-