GB2038998A - A valve - Google Patents

Abstract

A valve comprises a body 1 having an inlet connection 2 and an outlet, connection 3 and a valve seat associated with each of the connections. A displaceable valve element 22 is in sealing engagement with each valve seat in the closed position of the valve and the two displaceable valve elements are connected together by a common drive. A spring 17 urges the valve to its closed position. The valve also comprises a pressure chamber 29 which is defined between the valve seats and is closed when the valves are closed. The chamber is provided with a connection for a pressure meter or a pressure monitor so that it may be used as a tightness measuring chamber. <IMAGE>

Description

SPECIFICATION A valve The invention relates to a valve with a casing with an inlet and outlet connection and a valve seat associated with each of the connections. A displaceable valve element engages tightly with each of the seats in the closed position of the valve. The two displaceable valve members are connected by a common drive, and define a chamber which is surrounded by the casing and is sealed when the valves are closed.

Such valves have been previously proposed in various constructions (DE-PS 581 479, DE-PS 51 90, FR-PS 608 182). They serve for the most varied purposes. Their drive is manual, preferably by means of a screw spindle. The chamber between the valve seats serves merely for receiving the displaceable valve elements and the constructional components and in supporting and displacing the valve elements.

Such valves are known in the most varied constructional forms and with many kinds of drive.

For example, such valves are constructed as plate valves, diaphragm valves or displaceable ball valves, and manual drives as well as remotely controllable electro-magnetic, pneumatic or hydraulic drives may be provided.

For use in gas combustion installations, such valves are in general constructed as electromagnetic valves and disposed between the gas supply pipe and the burner. For safety reasons, two valves are frequently provided in order to ensure reliable closure of the gas supply pipe in every case, because gas which leaks or flows in after the burner has been switched off and the valve is not tight, may mix with air and form an ex'plosive gas mixture which can be the cause of considerable danger.In order to be able to test the tightness of the two valves in the assembled state, the usual procedure is that with the valves closed the space between the two valves, which consists partly of the inner space of the valve and partly of connecting tubes located therebetween and under certain circumstances of further elements, is changed as to the pressure relatively to the pressure normally prevailing therein, whereupon an examination is made by means of a pressure meter or a pressure guard, whether or how quickly the pressure in the closed system changes, this being a measure of the tightness. It is to be noted in this case that for systems which are tight in a technical sense, a sufficient tightness may be defined by the fact that for a given volume and a given period of time no or only a small predetermined pressure change must occur.In other words the determination of the permissible leakage rate is reduced to a time measurement In principle a pressure may be provided in this case which is higher or lower in relation to the pressure in the supply pipe. At a higher pressure, in principle both valves are tested simultaneously for tightness, whereas at a lower pressure care must be taken that this pressure differs from atmospheric pressure, because otherwise the tightness of the valve closing in the direction of the burner is not examined reliably enough. On the other hand the use of a pressure lying below the atmospheric pressure is likewise problematic, because then, when the valve near the burner is leaky, additionally air penetrates into the closed space in which the gas is located.

The object of the present invention is seen in the provision of a valve which permits equipment for tightness control to be constructed in a more economical manner and the tightness control to be standardised.

This problem is solved according to the present invention in a valve of the kind referred to above in that the chamber is provided with a connector for a pressure sensitive element, for example a pressure meter or a pressure guard, for the purpose of using the chamber as a tightness chamber.

By the use of a valve according to the invention, not only is the expenditure considerably reduced which is otherwise necessary for two valves in respect of the production as well as in respect of the assembly, but it is also ensured at the same time that the volume of the space or the chamber, respectively, between the two valve members is always the same from equipment to equipment, because it is determined by the constructional sie of the valve employed. For this reason a "standardisation" of the tightness control can be attained, because a decisive quantity which heretofore could not be determined in advance, namely the volume of the chamber, is fixedly predetermined.It is possible thereby to operate with predetermined pressure differences or time values, respectively, during the determination of the tightness or leakage rate, without the need for an expert to determine these quantities individually after the completion of each installation. Thereby not only the expenditure for the construction and commissioning of such a gas combustion installation is reduced, but also an increased safety for correct dimensioning is obtained, because sources of error are excluded.

The arrangement for tightness control usual heretofore which is imperative for reasons of safety in the case of gas combustion installations, is considerably simplified by the use of a double valve with a chamber located between the valve seats, in contrast to individual valves with pipe line sections located therebetween, and is therefore rendered more reliable for practical use. By means of a relatively minor change of the known double valves an important cost advantage and a considerable saving of expenditure for accounting and investment can be obtained as well as also increased reliability in respect of calculation errors.

Furthermore an additional simplification may be obtained by the fact that the pressure meter or the pressure guard is attached directly to the valve; this may even be effected in the works, so that the compact unit which is being built in consists of the double seat valve and the pressure guard.

In general the displaceable valve members rest on the valve seat under the force of a spring. In a preferred embodiment of the invention the two displaceable valve members are biased by a common spring. In this case the common spring is preferably constructed as a compression coil spring and each end thereof abuts a respective one of the two displaceable valve members. Thus spring plates for receiving the spring ends are formed on or attached to the valve members. The spring is simultaneously the return spring of the drive. In this case, in a preferred further embodiment, each of the displaceable valve members is attached to the end of a respective leaf spring the other ends of which are attached to the casing approximately parallel to the seat plane of the valves.The leaf springs guide the displaceable valve members and increase the force exerted by the compression coil spring for the abutment against the valve seat of the displaceable valve member in the closed position (since when the drive is not actuated the valve forms described are closed and are opened by the drive).

Preferably the valves are constructed as plate valves and the displaceable valve members are constructed as valve plates. However it is also possible and provided in preferred constructional forms of the invention that the valves are constructed as swinging ball valves the displaceable members of which comprise the configuration of a ball or spherical segment. The latter has advantages when, for the purpose of further reducing the pressure loss of the valve according to the invention, this valve is to be constructed as a "free flow valve," because such a ball or spherical segment can be easily swung out of the flow cross-section.

The drive provided is preferably an electromagnet with an armature which is attached to the other end of the plunger.

The invention will now be further described by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is á longitudinal section through a double valve with toggle lever drive, and Fig. 2 is a longitudinal section through a double valve with angle lever drive.

The valve illustrated in Fig. 1 comprises a valve casing 1 with an inlet bore 2 and an outlet bore 3 located opposite thereto. Two mutually oppositely disposed end faces 4 and 5 in which the bores 2 and 3 terminate are constructed in such a manner that they may be sealingly connected directly to the casing of adjacent devices, such as for example regulators or filters, without a tube connection being necessary therebetween. For this purpose an annular groove surrounding the bore is worked into one of the two end faces 4 and 5 and an O-ring 6 is inserted therein. The groove receiving the O-ring 6 is followed by a centring collar 7 which projects from the plane of the end face and surrounds the bore.The oppositely disposed end face is provided with a centring attachment 8 the diameter of which matches the diameter of the centring collar 7, so that the valves can be easily connected in series to form a compact constructional unit.

One side of the valve casing 1 has attached thereto a drive casing 9 with a closure cap 10 which covers a stroke adjustment member not illustrated further. A connection box 11 for producing the connection to the electrical feed of an electro-magnet is attached laterally to the drive casing 9; the electro-magnet is located within the drive casing 9, but is not illustrated in detail. The electro-magnet acts on an armature which is connected to a plunger 12 or is formed by one end of the plunger 12, respectively. The other end remote from the end of the plunger 12 is provided witha spring plate 13 which is slightly displaceable and which supports a sleeve 1 4 with a sealing lip 15 which slides in a tube-section 16 which is part of the drive casing 9 and surrounds the plunger 12 concentrically.A compression coil spring 1 7 is located within the tube section 1 6 and the sleeve 14 and is supported at the one end on the spring plate 1 3 and at the ohter end on the drive casing 9; it displaces the plunger 12 into the position illustrated in the drawing, or retains it in this position, respectively, in which the valve is closed when the electro-magnet is not energised.

Two guide members 1 8 and 1 9 are rotatable about a common axis in the form of a pin 20 at the free end of the spring plate 13. The other ends thereof are pivotally attached to a stub attachment 21 of a respective valve plate 22 and are rotatable about pivots 23. The valve plates 22 each comprise a disc 24, the side thereof which faces the inner space of the valve casing 1 having the stub attachment 21, whereas a resilient sealing ring 25 with an appropriate sealing rim is attached to the oppositely disposed side, the sealing ring 25 abutting a valve seat 26 when the valve is closed.In order to centre the two valve plates 22 relatively to the valve seats 26 (and thus also the bores 2 and 3), leaf springs 27 are provided which on the one hand are fixed to the casing by means of clamping members 28 and on the other hand embrace the respective stub attachment 21. The leaf springs 27 permit a movement approximately perpendicular to the plane of the valve seats 26, but largely prevent movements about axes parallel to the valve seat plane, that is to say for example the shaft 23 or axes parallel to the longitudinal axis of the plunger 12.

In the illustrated closed position of the valve the compression coil spring 1 7 presses the plunger 12 into its end position in which it presses the displaceable valve members in the form of the valve plates 22 against the valve seats 26 by means of the pins 20 and the toggle lever arrangement of the guide members 18 and 19. In this case the power of the compression coil spring may be relatively small because of the mechanical advantage of the toggle lever arrangement. When the electro-magnet located in the drive casing 9 is energised, it attracts the plunger 12 and the valve plates are lifted off the valve seats 26 against the effect of the compression coil spring 1 7 and the leaf springs 27.

The internal space enclosed by the valve casing 1 forms a chamber 29 which is provided with a connection not illustrated for a pressure guard or pressure meter which is part of a tightness monitoring device.

In the constructional form illustrated in Fig. 2 identical component parts are provided with the same reference numeral and mutually corresponding parts are provided with a reference numeral increased by 50.

The valve illustrated in Fig. 2 comprises avalve casing 51 with an inlet bore 52 and an outlet bore 53 which terminate in mutually oppositely disposed end faces 54 and 55. An annular groove enclosing the bore is worked into each of the end faces, and a respective O-ring 56 is inserted therein for sealing. Therefore a direct flange connection can be produced with devices or connecting component parts which comprise a plane counterface for the O-ring 56.

The electro-magnet accommodated in the drive casing 9 but not illustrated in detail actuated a plunger 62. The end thereof which is located in the valve casing 51 is provided with an annular groove 80 cut in deep, and the angle attachments 81 of angle levers 82 are engaged at opposite sides of the groove 80, the angle lever 82 being rotatable about a pin 83 rigidly attached to the casing. Rotatable about a pin 84, a stub attachment 71 of a valve plate 72 is rotatably attached to the other end of the angle lever 82.

The valve plate 72 comprises a disc 24 the one side of which has the stub attachment 71 attached thereto, whereas a resilient sealing ring 25 is attached on the oppositely disposed outward facing side. In the illustrated closed position of the valve, the sealing ring 25 comes into abutment with a respective valve seat 26 which surrounds th;e bore 52-or 53, respectively. The pins 83 and 84 are arranged parallel to each other and to the plane of the valve seat 26. They extend tangentially relatively to the direction of movement of the plunger 62.

A common compression coil spring 67 is located between the two oppositely disposed valve plates 72 with the two ends thereof supported on respective collars on the stub attachments 71, and moves the valve into the closed position when -the electro-magnet is deenergised.

In the closed position, the valve illustrated in Fig. 2, comprises also a chamber 29 which is limited by the valve casing 51 and which is provided with a connection not illustrated for a pressure monitor or a pressure meter. Both valves are disposed symmetrically with respect to a centre plane which in turn is parallel to the plane of the valve seats 26 and to which the axes of the inlet and outlet bores 2, 3 and 53, 53, respectively, are perpendicular.

It is understood that the invention is not limited to the constructional examples illustrated, but that deviations therefrom are possible without departing from the scope of the invention. In particular some features may be employed by themselves or in any desired combination. For example it is not necessary that the valve is constructed symmetrically and the two valve plates perform mutually oppositely directed symmetrical movements. For example it is also possible to mount two valve plates on a common plunger in a resiliently displaceable manners so as to come into abutment with valve seats disposed at a mutual spacing and which lift off the valve seats in the same direction. In this case the mutually parallel planes of the valve seats are disposed perpendicular to the direction of movement of the plunger and the armature of an actuating electro-magnet, and the inlet direction and the outlet direction parallel thereto extend approximately parallel to the valve seat plane. In front of the valve seat associated with the inlet and beyond the valve seat associated with the outlet a diversion of the gas stream through approximately 90 is then always effected.

It is essential for the present invention that the displaceable valve members and the valve seats are provided in dulpicate and form between them a chamber which is closed when the valves are closed and which is useable for a tightness control.

Claims (6)

1. A valve comprising a body with an inlet and an outlet controlled by respective shut-off elements having a common drive and defining therebetween when closed a pressure chamber adapted to be connected through a wall thereof to pressure sensing means.

2. A valve as claimed in claim 1, wherein the two shut-off elements are biased by a common compression coil spring which also serves as a return spring for the common drive.

3. A valve as claimed in claim 2, wherein each shut-off element is attached to one end of a respective leaf spring which is attached by its other end to the valve body approximately parallel to the valve seat plane.

4. A valve as claimed in any one of claims 1 to 3, wherein the shut-off elements are provided by a displaceable ball valve the displaceable members of which comprise the configuration of a sphere or a spherical segment.

5. A valve as claimed in claim 1, wherein an electromagnet with an armature attached to the other end of the plunger is provided as the drive.

6. A valve substantially as described with reference to and as illustrated in Fig. 1 or Fig. 2 of the accompanying drawings.