GB2117091A

GB2117091A - Streamlined non-return valve

Info

Publication number: GB2117091A
Application number: GB08303981A
Authority: GB
Inventors: Sandro Bonomi
Original assignee: Bonomi Ilario & C Enol Gas
Current assignee: Bonomi Ilario & C Enol Gas
Priority date: 1982-02-17
Filing date: 1983-02-14
Publication date: 1983-10-05
Also published as: FR2521679B3; GB2117091B; AT378586B; GB8303981D0; ATA118482A; ES270379Y; IT1157513B; DE8303011U1; ES270379U; IT8205122A0; FR2521679A3

Abstract

The valve comprises a body portion (1) enclosing a plug or sealing member, the plug or sealing member comprising a stationary guide member (10) secured to the body portion (1) and an axially displaceable member (15) guided by and displaceable relative to the stationary member, the axially displaceable member engaging the valve seat (6) in its closed position. The stationary member has a central tapered portion with a conical external surface (14) tapering inwardly in the direction of fluid flow and a base portion (14') facing the valve seat, the displaceable member has a tapered head portion having a conical external surface (17) tapering inwardly in a direction opposite to the fluid flow and a base portion (17'') facing the base (14') of the tapered portion of the stationary member, the tapered head portion of the displaceable member is provided with a rod or stem (16) which is guided in an axial bore (13) formed in said tapered portion, a spring (19) biasses the displaceable member towards the valve seat. The base of the tapered head portion (15) of the displaceable member (8) and the tapered portion of the stationary guide member (7) engage with one another so that the two tapered portions form a biconical unit having a substantially continuous external surface when the valve is in its open position. <IMAGE>

Description

SPECIFICATION Improved non-return valve The present invention relates to a non-return valve which includes an improved plug or sealing unit comprising an axially displaceable tapered member which opens and closes the valve.

Various forms of non-return valves, also known as check or one-way valves, which are designed to prevent any flow of fluid in a direction opposite to the desired direction of flow are already known.

Thus, for example, non-return valves having a spherical plug member are known. However, it is difficult to ensure a reliable and permanent sealing with a spherical plug member particularly when the valve is frequently opened and closed. In such a system the effect of wear on the sphere tends to produce a groove on the sealing periphery. This, in time, leads to fluid leakage through the valve.

Non-return or one-way valves which includes a mushroom-shaped or disc-shaped plug member and those of the gravity or spring type which are intended to bear against the seat of the valve which is to be closed are also known. In such an arrangement, it is possible to maintain a permanent seal between the mushroom-shaped or disc-shaped plug and the valve seat, but the design of the plug and the corresponding guide member therefor leads to head losses and high turbulence in the fluid flow. It has not, hitherto, been possible to eliminate this problem.

The present invention seeks to provide a nonreturn valve having an improved plug unit in which reliable sealing is achieved when the valve is closed but which reduces the head losses and turbulent flow to a minimurn when the valve is in its open position. The invention also seeks to provide a non-return valve which can be used in any position and condition for any liquid or gaseous fluids without adversely affecting the flow.

According to the present invention, there is provided a non-return valve comprising a body portion enclosing a plug or sealing member, the plug or sealing member comprising a stationary guide member secured to the body portion and an axially displaceable member guided by the displaceable relative to the stationary member, and axially displaceable member engaging the valve seat in its closed position, wherein the stationary member has a central tapered portion having a conical external surface tapering inwardly in the direction of fluid flow and a base portion facing the valve seat, the displaceable member having a tapered head portion having a conical external surface tapering inwardly in a direction opposite to the fluid flow and a base portion facing the base of the tapered portion of the stationary member, the tapered head portion of the displaceable member being provided with a rod or stem which is guided in an axial bore formed in said tapered portion, a spring being provided which tends to displace the displaceable member towards the valve seat, the spring being located between the two tapered portions, the bases of the tapered head portion of the displaceable member and the tapered portion of the stationary guide member engaging with one another so that the two tapered portions form a biconical unit having a substantially continuous external surface when the valve is in its open position.

One embodiment of a non-return valve in accordance with the present invention will now be described, by way of example, with reference to the accompanying drawing, in which: Fig. 1 shows an axial cross-section of the valve in its closed position, Fig. 2 shows a view similar to Fig. 1 but with the valve in its open position, Fig. 3 shows a transverse cross-section along the line Ill-Ill of Fig. 1, and Fig. 4 shows a perspective view of a plug unit forming part of the valve.

As shown in the drawing, a valve comprises a tubular body member 1, in the interior of which a cylindrical chamber 2 is defined. The chamber 2 includes a conical shoulder portion 3 towards its base. A sleeve portion 4 which is affixed to the body portion 1 by means of, for example, a thread, at the mouth of the chamber 2.

The sleeve 4 carries a packing seal 5 which, as shown, is reinforced by a metal ring 5'. The seal constitutes and defines the valve seat 6 to be opened and closed by the inflow of the delivered fluid. The direction of flow of the fluid is denoted by the arrow F in Fig. 2.

A plug unit comprising, as shown in Fig. 4, a stationary guide member 7 and a movable member 8 which is guided by and displaced axially with respect to the stationary member 7 is located in the chamber 2.

The guide member 7 comprises an annular portion 9 having an external diameter corresponding substantially to that of chamber 2 and an internal diameter which is greater than the diameter of the valve seat 6, and a tapered portion 10 which is coaxial with the annular portion 9 but is axially spaced therefrom. The portions 9 and 10 are rigidly interconnected by means of radial fins 11, between which fins are defined openings or passages 12. The tapered portion 10 of the guide member 7 has an axially extending guide bore 13 formed therein. The external conical surface 14 of the portion 10 is located so that the inward tapering extends in the direction of flow of the fluid that is to say, in the direction of arrow F, and includes a base portion 14' facing the mouth.The conical surface 14 may be defined by a straight generatrix or, more advantageously from the point of view of fluid dynamics, by a multiple-radius generatrix as shown in the drawing.

The radial fins 11 extend from the annular portion 9 to points adjacent the smallest diameter portion 14" of the tapered portion 10 in such a manner as to project radially from the conical surface 14 of the tapered portion. The fins 11 are bevelled at their ends 11' so as to fit against the conical shoulder portion 3 in the base of the chamber 2.

The stationary member 7 of the plug unit is, in use, located in the chamber 2 of the body portion 1 and is secured between the conical shoulder portion 3, against which the bevelled portions 11' of the radial fins 11 abut and the sleeve 4 against the annular portion 9 bears directly and/or indirectly via the seal 5.

The movable member 8 of the plug unit has a tapered head portion 1 5 which is guided between the fins 11 of the stationary member, and a stem 1 6 which is directed towards, and is guided through, the axial bore 13 formed in the tapered portion 10 of the stationary member 7. In this way, the movable member is guided at two points and is always correctly located with respect to the seat 6. The tapered head portion 1 5 also has a conical exterior surface 1 7 with a reduced diameter portion 17' directed opposite to the direction of fluid flow and terminates in a base 1 7" which faces the base portion 14' of the tapered portion 10 of the stationary member 7.

The base 1 7" of the tapered head portion 1 5 of the displaceable member 8 has a diameter which is iess than the internal diameter of the annular portion 9 of the stationary member but which corresponds to the diameter of the base 14' of the tapered portion 10. The diameter of the base portion 17" of the tapered head portion 15 is, in all circumstances, greater than the diameter of the valve seat so that a peripheral portion 1 8 of the displaceable member 8 can rest against the seal 5.

The spring 19, which tends to displace the displaceable portion towards th seal 5 in the closed position of the valve, is located between the tapered portion 10 of the stationary guide member 7 and the tapered head portion 1 5 of the displaceabie member 8. The spring is therefore held between the two portions and cannot possibly disturb the flow of fluid.

Finally, it should be noted that the side of the annular portion 9 opposite to that engaged by the sleeve 4 andior the packing 5 has a conical surface which opens out in the direction of the flow of fluid so as to extend generally parallel to the conical surface of the tapered head 1 5 of the displaceable member 8.

In Fig. 1 of the drawing, the valve is shown in its closed pOsition. This is achieved by the action of the spring 1 9 which displaces and holds displaceable member 8 against the seal 5 and prevents fluid flowing past the valve seat 6. In this position, return flow of fluid towards the upstream part of the valve is not possible.

During the normal delivery of fluid in the direction of arrow F, the displaceable member moves so that the base 1 7" of its tapered head member 15 rests against the base 14' of the tapered portion 10 of the stationary member 7. It thus forms, with the latter, a bi-conical unit having external surfaces which are substantially continuous, as is best seen in Fig. 2. Moreover, together with the conical surface 20 of the annular portion 9 and the surfaces of the cylindrical chamber2 and the conical shoulder portion 3, it defines a conduit or passage 21 which has an essentially venturi-form shape, although its crosssectional is constant over its entire length.

Accordingly, the fluid entering the valve is gently divided by the narrower portion 17' of the tapered head portion 1 5 and is caused to pass into the conduit 21 where it is constantly guided from both the centre of the valve and from the exterior.

The continuity and shape of the surfaces which define the conduit 21 thus effectively reduce both head losses and turbulence in the fluid to a minimum. This is true both when the fluid enters and leaves the valve. The production of this effect is also assisted by the presence of the radial fins 11 of the stationary member 7, which fins tend to straighten the fluid flow lines and prevent turbulence associated with the axial rod or stem 1 6 of the displaceable member when the fluid leaves the conduit 21.

Claims

1. A non-return valve comprising a body portion enclosing a plug or sealing member, the plug or sealing member comprising a stationary guide member secured to the body portion and an axially displaceable member guided by and displaceable relative to the stationary member, the axially displaceable member engaging the valve seat in its closed positiOn, wherein the stationary member has a central tapered portion having a conical external surface tapering inwardly in the direction of fluid flow and a base portion facing the valve seat, the displaceable member having a tapered head portion having a conical external surface tapering inwardly in a direction opposite to the fluid flow and a base portion facing the base of the tapered portion of the stationary member, the tapered head portion of the displaceable member being provided with a rod or stem which is guided in an axial bore fromed in said tapered portion, a spring being provided which tends to displace the displaceable member towards the valve seat, the spring being located between the two tapered portions, the bases of the tapered head portion of the displaceable member and the tapered portion of the stationary guide member engaging with one another so that the two tapered portions form a biconical unit having a substantially continuous external surface when the valve is in its open position.

2. A non-return valve as claimed in claim 1, in which the tapered portion of the stationary guide member is made integrally with an annular portion by means of radial fins, passages or apertures being defined between the fins, the stationary member being secured to the body portion by means of a conical shoulder portion and a sleeve which is detachably affixed to the body portion, the sleeve bearing a seal defining the valve seat, the radial fins being bevelled so as to fit the conical shoulder.

3. A non-return valve as claimed in claim 2, in which the external surfaces of the two tapered portions, when fitted together. form a biconical unit which defines, together with the inner surfaces of the annular portion, the body portion of the valve and the conical shoulder portion. a conduit or passage having a venturi-form shape.

4. A non-return valve as claimed in any preceding claim, in which the conical external surfaces of the two tapered portions are each defined by straight generatrices or by generatrices which incorporate a plurality of radii.

5. A non-return valve as claimed in claim 1 constructed and arranged to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.