US2904074A - Decompression valve - Google Patents

Description

Sept. 15, 1959 J. M. TOWLER 2,904,074

DECOMPRESSION VALVE 'Filed Feb. 20, 1956 v v INVENTOR JOHN MAURICE TOWLER C A @FRANK-HATHORN "FOWLER, EXECUTOR BY JZQM WH/ ATTOR EYS DECOMPRESSION VALVE John Maurice Towler, deceased, late of Mayfair, London, England, by Frank Hathorn Towler, executor, Dob Park, Otley, England, assignor to Electraulic Presses Limited, Rodley, England, a limited-liability company of Great Britain Application February 20, 1956, Serial No. 566,658

Claims priority, application Great Britain February 25, 1955 '6 Claims. (Cl. 137-63015) This invention relates to decompression or exhaust valves of the kind which for example are used to release the compressed energy of the liquid in a hydraulic press cylinder prior to opening the prefill-exhaust valve for the return stroke of the press ram.

One object of this invention is to provide a decompression valve of simple and improved construction such that the compressed energy may be released in 'a fraction of a second without causing serious shock or pressure surge in the associated hydraulic system. A further object of this invention is to provide a decompression valve so constructed that the compressed energy may be released at a controlled rate.

Broadly the present invention consists in a decompression or exhaust valve for releasing the compressed energy in a hydraulic cylinder, for example the cylinder of a hydraulic press, said valve having a valve member which is movable axially in relation to a series of passages the arrangement being such that as the valve moves it first opens an exhaust port and then uncovers in turn the series of passages to permit the compressed liquid in the hydraulic cylinder to have access to the open exhaust port at a controlled rate for the purpose of preventing a too rapid release and serious shock or pressure surge in the hydraulic system.

One embodiment of this invention comprises a decompression valve for a hydraulic press consisting of a mushroom type valve opening into the press cylinder and so constructed and arranged that the head of the said valve is surrounded by a cylindrical shroud having a number of radial passages throughout its length so that, as the valve opens, the said passages are uncovered by the valve head consecutively thereby controlling the rate of access of compressed liquid in the press cylinder to the annular passage uncovered by the said valve. It will be understood that the said valve may be moved axially a distance equivalent to about half the diameter of the valve seat and the said valve movement may be effected by means of an actuating cylinder or other suitable means.

In order that the invention may be clearly understood a decompression valve according to the above embodiment will now be described by way of example, by aid of the accompanying drawing which shows the same in vertical section mounted concentrically in the head of the prefill-exhaust valve of the hydraulic press cylinder.

Referring to the drawing the decompression valve has an actuating spindle 1 and a mushroom head 2 and it is mounted for relative movement concentrically in the head of a prefill-exhaust valve 3, which latter is seated in the end of the press cylinder at 4.

The decompression valve head 2 is surrounded by a cylindrical shroud 5 forming, in the drawing, an integral extension on the underside of the prefill-exhaust valve 3. The shroud 5 is perforated with a large number of radial passages 6, of any convenient cross section which in the illustrated example are arranged on a helix. Thus as the valve head 2 is moved downwards, looking at the drawing, the radial passages 6 are uncovered consecu United States Patent 0 i 2,904,074 Patented Sept. 15, 1959 ice tively andthe compressed liquid in the press cylinder has access through ports 7 in the prefill-exhaust valve 3 to the interior of the prefill tank 8 to a gradually increasing extent with the object of releasing the compressed energy of the liquid at a controlled rate.

A similar eflect may be obtained by disposing the radial passages 6 in a series of rows one below the other so that asthe decompression valve head 2 opens it uncovers each row of passages in turn.

In the example illustrated the decompression valve is opened against the pressure in the press cylinder by hydraulic pressure acting against an enlarged ram head 9 the area of which is greater than the area of the valve 2 which is exposed to the pressure within the press cylinder. The enlarged head 9 works in a cylinder 10 and co-acts with the inner end of the actuating spindle 1 of the decompression valve through a ram 11. The return or closing movement of the decompression valve is effected by a spring 12.

It will be understood that the embodiment illustrated is designed for a downstroking press and therefore both the prefill-exhaust valve and the decompression valve are opened by being moved downwards into the press cylinder. However, such valves may be mounted horizontally for a press ram and cylinder acting horizontally or vertically upward for the cylinder of an upstroking press without departing from the invention.

What is claimed is:

1. A prefill and exhaust valve mechanism for controlling fluid flow in a hydraulic system comprising, in combination, a prefill and exhaust valve member movable between open and closed positions, said valve member having a bore with a port opening from the bore to the exhaust side of the member and a series of passages opening from the bore to its pressure side of the member, and an auxiliary valve member reciprocable in the bore of said exhaust valve member to initially open said port and then establish communication between the port and said passages in succession to permit exhaust of compressed fluid at a controlled rate effective to avoid a pressure surge.

2. A valve mechanism as defined in claim 1 in which the auxiliary valve member is a mushroom-type valve and in which the series of passages controlled by the auxiliary valve open radially through a shroud formed on the exhaust valve member around the head of the auxiliary valve member.

3. A valve mechanism as defined in claim 2 in which the radial passages are arranged in a helix so as to be uncovered consecutively as the auxiliary valve moves toward open position.

4. A valve mechanism for controlling fluid flow in a. hydraulic system comprising, in combination, a prefill and exhaust valve member movable between open and closed positions, said valve member having a bore opening to both its pressure and exhaust sides, a decompression valve member reciprocable in said bore operative in one position to close the bore, an integral extension on the pressure side of said exhaust valve member having a series of passages opening therethrough outwardly from the bore at the pressure side of the valve member, said decompression valve member being operative in its movement from closed positions to open said passages successively to said bore to permit a gradual release of pressurized fluid and thereby avoid excessive shock or pressure surge.

5. A valve mechanism as defined in claim 4 including a pressure fluid operated actuator for moving the decompression valve member from closed toward open position.

6. A prefill and exhaust valve comprising, in combination, means defining a valve port, a main valve member movable relative to said port between open and closed fashions, said valve member having an exhaust passage 7 in-commtmication with an exhaust port at its low pressure side and with a series of restricted passages at its high pressure side, and an auxiliary valve member Ieciprocable *in-thepassage -insaid main-valve member from aposition clp'sing saidexhaust port to a position efiective to establ'ish communicationbetween said exhaust port and said redrieted passages in succession.

- Relentless Cited the file of this patent STATES PATENTS Blyston May 7, 1929 Ernst Dec. 27, 1933 Cannon Jan. 16, 1940 Cones July 31, 1945 Brehm Oct. 24, 1950 v Nowak Dec. 23, 1952 FOREIGN PATENTS Sweden Nov. 13, 1897

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