GB1593890A

GB1593890A - Fluid pressure responsive valve

Info

Publication number: GB1593890A
Application number: GB53874/77A
Authority: GB
Original assignee: REGEL MESSTECHNIK GmbH
Current assignee: REGEL MESSTECHNIK GmbH
Priority date: 1976-12-27
Filing date: 1977-12-23
Publication date: 1981-07-22
Also published as: DE2658988C2; NL7714190A; AT382028B; DE2658988A1; FR2375531A1; CH624749A5; ATA861377A; FR2375531B3

Abstract

In the safety shut-off valve, the flow of medium in the presence of an impermissible pressure on the outlet side of a gas-pressure regulating system is shut off automatically. In this arrangement, a plurality of elements are combined in one housing to give a functional unit. The force of a closing spring acts on a release mechanism. The release mechanism comprises an actuating rod (1), arranged at the upper end of which is a valve plate (2) and, in the central region (1a) of which are arranged a guide bush (3) and an actuating bush (4). The guide bush (3) cooperates equally with units (12) comprising springs (12a) and balls (12b) and with the actuating rod (1d) designed to correspond partially to the balls (12b), to give a first detent which bears the main load. This detent can be released in the manner of a cascade by means of a second detent, which is constructed in the same way, comprises actuating bush (4) and further balls (5) distributed around the circumference and the actuating rod (1b) designed to correspond partially to these further balls (5) but bears a smaller load. This safety shut-off valve with a large nominal width has the necessary closing force without, at the same time, imposing an excessively high load on the release mechanism. <IMAGE>

Description

(54) A FLUID PRESSURE RESPONSIVE VALVE (71) We, REGEL + MESSTECHNIK GmbH REGLER-UND ANLAGENBAU FÜR GAS DRUCKREGELUNG, a Joint Stock Company organised under the laws of Germany (Fed. Rep.) of Osterholzstrasse 45, D-3500 Kassel-Bettenhausen, Germany (Fed, Rep.), da 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: This invention relates to a fluid pressure responsive valve and more particularly to a safety cut-off valve.

It is known, for example in gas pressure regulating installations, to provide a safety cut-off valve which interrupts the flow of gas when pressure fluctuations at the outlet side of the installation exceed predetermined tolerances. Thus it has been previously proposed to incorporate in such a valve a trip mechanism which is operable to release the valve element from its open position and permit it to return to the closed position under the action of an associated closure spring. The trip mechanism of previously proposed valve constructions have, however, suffered from design disadvantages as a result of which the size of such valves, particularly in relation to the force of the closure spring, has been restricted.

According to the present invention there is provided a safety cut-off valve comprising a valve body with an opening through which fluid can flow, a valve element mounted on a valve stem which is movable between a closed position in which the valve element closes said opening and an open position in which the valve element is remote from said opening, a biasing spring for biasing said valve stem into one of said positions, and first and second detent means together capable of holding the valve stem in the other of said positions against the spring pressure, the second detent means including a control member which is movable under the influence of pressure variations of the fluid flow above a predetermined amount to release the second detent means whereupon the biasing spring overrides the first detent means and returns the valve stem with full spring pressure into said one position.

Preferably, the first and second detent means each comprise balls arranged around the axis of the valve stem, retaining means for retaining the balls in a fixed position lengthwise of said axis, and biasing means for biasing the balls towards said axis so as to engage in recesses in said valve stem when the valve stem is in said other of said positions. The transition surfaces beteen the recesses and the full diameter of the valve stem are preferably frusto-conical.

Preferably, the retaining meas for both detent means are provided by a common guide bush fixed in the valve body and traversed by the valve stem, the guide bush having ball-retaining openings at two locations therealong corresponding to the positions of the two detent means.

Springs are preferably used to provide the biasing means of the first detent means and the biasing means of the second detent means is preferably provided by internal projection(s) of a control sleeve engaging over the respective retaining means.

Preferably, the control sleeve is carried by a diaphragm arranged to respond to said pressure variations of the fluid flow, and the internal projection(s) is(are) radially inwardly tapered.

The invention will now be further described by way of example only with reference to the accompanying drawing which is a diagrammatic longitudinal section of one embodiment of safety cut-off valve in accordance with the invention.

In the drawing, an actuating rod or valve stem 1 is fixed to a valve disc or valve element 2. The actuating rod 1 is also mounted in a guide bush 3 and projects through a trip mechanism, which comprises a central part la of the actuating rod 1, a lower part 3a of the guide bush 3, an actuating bush 4 and balls 5 (second detent means). In its lower part, the actuating rod 1 has a wide recess ib, in which the balls 5 can engage. The balls 5 are in turn located in bores 3b of the lower part 3a of the guide bush 3. The actuating bush 4 is structurally connected to a diaphragm 6 of a control device and serves for engaging and disengaging the ball arrangement. A closing spring 7, for example a compression spring, is located between the valve disc 2 and base 8 of a housing 9.The force of the closing spring 7 is chosen such that even at low operating pressures, a sealing ring 10 in a groove 2a of the valve disc 2 is defined in order to produce a seal between the valve disc 2 and valve seat 11.

When the valve is open, the trip mechanism is engaged and the force of the closing spring 7 acts by way of the valve disc 2 and actuating rod 1 on the balls 5 of the trip mechanism.

Now in order to prevent excessive pressure between the balls 5 and the actuating rod 1, a plurality of ball and spring arrangements 12 (first detent means) are distributed peripherally around the stem 1 in order to reduce the closing force in the spring 7.

The method of operation of the ball and spring arrangements 12 is by spring force acting on the balls 12b which provides two components of force. One of these components thus acts on the inclined surface id on the actuating rod 1 as a counter-force and reduces the force of the closing spring 7 acting on the balls 5. The other component of force acts on the bore 3c in the guide bush 3.

The method of operation of the safety cut-off valve with its trip mechanism and the ball and spring arrangements is as follows: Opening of the valve disc 2 takes place due to pressure on a knob (not shown) attached to the upper end of the actuating rod 1.

Thus, the actuating rod 1 is moved downwards until the actuating bush 4 which is loaded by reference valve springs 14, 15 engages the balls 5 in the recess lh of the actuating rod 1. At the same time, the balls 12b of the ball and spring arrangements 12 engage in the recess lc located thereabove in the actuating rod 1 and produce a counterforce. The force of the closing spring 7 acting on the balls 5 is reduced by this counter-force. As a result of the engagement of the balls 5, a releasable connection is produced between the stationary guide bush and the movable actuating rod 1. The closing spring 7 is tensioned at the same time as the shifting movement of the actuating rod 1 during the opening operation. The outlet pressure of a gas pressure instillation is monitored by being supplied to the diaphragm 6 by a pipe 16.

If there is a sufficient pressure fluctuation for the safety cut-off valve to close, then the closing operation is initiated by the control device. The difference between the force of the reference value springs on the one hand and the outlet pressure acting on the diaphragm surface 17 on the other hand moves the diaphragm 6 with the actuating bush 4 downwards at the time of a pressure rise or upwards at the time of a pressure drop, so that the balls 5 release the actuating rod 1. The actuating rod 1, which is under the action of the closing spring 7, together with the valve disc 2 attached to the latter, carries out a shifting movement in the direction of the valve seat 11 and shuts-off the flow of medium. The inlet pressure of the blockedoff medium presses on the valve disc 2 thus reinforcing the sealing force of the closing spring 7.At the same time as the shifting movement of the actuating rod 1 during the closing operation, the counter-force produced by the ball and spring arrangements 12 is eliminated so that the force of the closing spring 7 is fully active in the closed position.

WHAT WE CLAIM IS: 1. A safety cut-off valve comprising a valve body with an opening through which fluid can flow, a valve element mounted on a valve stem which is movable between a closed position in which the valve element closes said opening and an open position in which the valve element is remote from said opening, a biasing spring for biasing said valve stem into one of said positions, and first and second detent means together capable of holding the valve stem in the other of said positions against the spring pressure, the second detent means including a conical member which is movable under the influence of pressure variations of the fluid flow above a predetermined amount to release the second detent means whereupon the biasing spring overrides the first detent means and returns the valve stem with full spring pressure into said one position.

2. A valve as claimed in claim 1, wherein the first and second detent means each comprise balls arranged around the axis of the valve stem, retaining means for retaining the balls in a fixed position lengthwise of said axis, and biasing means for biasing the balls towards said axis so as to engage in recesses in said valve stem when the valve stem is in said other of said positions.

3. A valve as claimed in claim 2, wherein the transition surfaces between the recesses and the full diameter of the valve stem are frusto-conical.

4. A valve as claimed in claim 2 or 3, wherein the retaining means for both detent means are provided by a common guide bush fixed in the valve body and traversed by the valve stem, the guide bush having ball-retaining openings at two locations therealong corresponding to the positions of the two detent means.

5. A valve as claimed in any one of claims 2 to 4, wherein springs provide the biasing means of the first detent means.

6. A valve as claimed in any one of

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. part 3a of the guide bush 3. The actuating bush 4 is structurally connected to a diaphragm 6 of a control device and serves for engaging and disengaging the ball arrangement. A closing spring 7, for example a compression spring, is located between the valve disc 2 and base 8 of a housing 9. The force of the closing spring 7 is chosen such that even at low operating pressures, a sealing ring 10 in a groove 2a of the valve disc 2 is defined in order to produce a seal between the valve disc 2 and valve seat 11. When the valve is open, the trip mechanism is engaged and the force of the closing spring 7 acts by way of the valve disc 2 and actuating rod 1 on the balls 5 of the trip mechanism. Now in order to prevent excessive pressure between the balls 5 and the actuating rod 1, a plurality of ball and spring arrangements 12 (first detent means) are distributed peripherally around the stem 1 in order to reduce the closing force in the spring 7. The method of operation of the ball and spring arrangements 12 is by spring force acting on the balls 12b which provides two components of force. One of these components thus acts on the inclined surface id on the actuating rod 1 as a counter-force and reduces the force of the closing spring 7 acting on the balls 5. The other component of force acts on the bore 3c in the guide bush 3. The method of operation of the safety cut-off valve with its trip mechanism and the ball and spring arrangements is as follows: Opening of the valve disc 2 takes place due to pressure on a knob (not shown) attached to the upper end of the actuating rod 1. Thus, the actuating rod 1 is moved downwards until the actuating bush 4 which is loaded by reference valve springs 14, 15 engages the balls 5 in the recess lh of the actuating rod 1. At the same time, the balls 12b of the ball and spring arrangements 12 engage in the recess lc located thereabove in the actuating rod 1 and produce a counterforce. The force of the closing spring 7 acting on the balls 5 is reduced by this counter-force. As a result of the engagement of the balls 5, a releasable connection is produced between the stationary guide bush and the movable actuating rod 1. The closing spring 7 is tensioned at the same time as the shifting movement of the actuating rod 1 during the opening operation. The outlet pressure of a gas pressure instillation is monitored by being supplied to the diaphragm 6 by a pipe 16. If there is a sufficient pressure fluctuation for the safety cut-off valve to close, then the closing operation is initiated by the control device. The difference between the force of the reference value springs on the one hand and the outlet pressure acting on the diaphragm surface 17 on the other hand moves the diaphragm 6 with the actuating bush 4 downwards at the time of a pressure rise or upwards at the time of a pressure drop, so that the balls 5 release the actuating rod 1. The actuating rod 1, which is under the action of the closing spring 7, together with the valve disc 2 attached to the latter, carries out a shifting movement in the direction of the valve seat 11 and shuts-off the flow of medium. The inlet pressure of the blockedoff medium presses on the valve disc 2 thus reinforcing the sealing force of the closing spring 7.At the same time as the shifting movement of the actuating rod 1 during the closing operation, the counter-force produced by the ball and spring arrangements 12 is eliminated so that the force of the closing spring 7 is fully active in the closed position. WHAT WE CLAIM IS:

1. A safety cut-off valve comprising a valve body with an opening through which fluid can flow, a valve element mounted on a valve stem which is movable between a closed position in which the valve element closes said opening and an open position in which the valve element is remote from said opening, a biasing spring for biasing said valve stem into one of said positions, and first and second detent means together capable of holding the valve stem in the other of said positions against the spring pressure, the second detent means including a conical member which is movable under the influence of pressure variations of the fluid flow above a predetermined amount to release the second detent means whereupon the biasing spring overrides the first detent means and returns the valve stem with full spring pressure into said one position.

6. A valve as claimed in any one of

claims 2 to 5, wherein the biasing means of the second detent means is provided by internal projection(s) of a control sleeve engaging over the respective retaining means.

7. A valve as claimed in claim 6, wherein the control sleeve is carried by a diaphragm arranged to respond to said pressure variations of the fluid flow.

8. A valve as claimed in claim 6 or 7, wherein the internal projection(s) is (are) radially inwardly tapered.

9. A safety cut-off valve substantially as herein described with reference to and as illustrated in the accompanying drawing.