GB2199116A

GB2199116A - A valve for a pressurised flowing medium

Info

Publication number: GB2199116A
Application number: GB8629977A
Authority: GB
Inventors: Erkki Pietari Niskanen
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-08-16
Filing date: 1986-12-16
Publication date: 1988-06-29
Also published as: SE8605452D0; GB8629977D0; DE3643063A1; SE455959B; FI73056B; FI853165A0; SE8605452L; FI73056C; FR2609143A1; FI853165L

Abstract

A valve for a pressurized flowing medium, comprises a body (1) having a valve chamber (2) and at least two connections (3,4). A counter piece (8) positioned within the valve chamber is attached to a spindle (5) provided with a valve disc (6). In order to make the body hermetically closed, the counter piece (8) forms a moveable piston of an actuator (9) positioned within the valve chamber (2), and a returning member (14) of the actuator is mounted within the body and separated from the valve chamber in a medium-proof manner. In order to balance the valve disc against pressure impacts, an area of the counter piece, on which area the pressure of the flowing medium acts in an axial direction of the spindle, equals in size a corresponding area (6a) of the valve disc. When a third connection (4') is provided, this area of the counter piece (8) is defined by a further valve disc (6') formed on the actuator (9). <IMAGE>

Description

A spindle valve for a pressurized flowing medium This invention relates to a spindle valve for a pressurized flowing medium, comprising - a body having at least two connections and a valve housing between the connections, - a spindle mounted axially slidably on the body and provided with a valve disc positioned within the valve housing, - an actuator for axial displacement of the spindle between a closed posItion for closing one connection and an open position for opening said connection, - a counter piece positioned within the valve housing and attached to the spindle, said counter piece forming a moveable element of the actuator positioned within the valve housing.

In practice there is often a risk of pressure impacts created within a pipe system, which pressure impacts may be many times greater than the normal medium pressure prevailing within the system. In food production industries, e.g., it is absolutely necessary that the closing element does not open unintentionally due to such instantaneous pressure impacts.

PCT Patent Application WO 84/03344 discloses a spindle valve in which a counter piece supported by a body is mounted in a valve housing so as to be positioned on the axial extension of an inlet connection. The area of the counter piece in a plane transverse with respect to the direction of movement of the spindle essentially corresponds to the cross-sectional area of the inlet connection. The closing element is cup-shaped, and it surrounds the counter piece in a medium-proof manner.

By virtue of such a structure, the closing element can be balanced, and the opening effect of the pressure of the medium and the forces caused by a possible pressure impact do not affect the closing element to any greater degree, because the stationary counter piece receives ali these strains.

In the valve according to the PCT application, the spindle displacing the closing element extends from the valve housing through the body of the valve up to an external actuator, e.g. a solenoid, by means of which the spindle can be drawn axially outwards for opening the valve. A compression spring returns the spindle to a closed position. However, sealing problems always arise due to the fact that a moving element, in this case the spindle, extends through the body to the outside of the valve housing, because there is a danger that the sealings get worn or fail for some other reason under the influence of the movement of the spindle, so that some medium leaks outside the body. An untight connection from outside the valve into the valve housing is formed in a similar way.

This is extremely disadvantageous in the food industries in particular.

The object of the present invention is to provide a spindle valve which avoids the above disadvantages and which can be made essentially fully balanced and hermetically closed even though the spindle is displaced by means of an actuator. This object is achieved by means of a spindle valve according to the invention, which is characterized in that - an area of the counter piece, which area is exposed to a medium pressure acting in the axial direction of the spindle, is essentially equal to a corresponding area of the valve disc, and - that a returning member of the actuator is mounted within the body and separated in a medium-proof manner- from the valve housing.

The invention is based on the idea that the counter piece provided for balancing the valve disc of the spindle against pressure impacts, is mounted on the spindle in stead of on the body, and that the counter piece, egualling in size with the valve disc, is used as a piston or a cylinder of the actuator displacing the spindle. In this way the actuator is wholly positioned within the valve body inside the valve housing, so that only the medium conduit(s) required for the operation of the actuator extend through the body, and these are easy to seal to the body in a quite liquid-proof manner by means of stationary connectors. It is thereby ensured that no undesired medium connection from the valve housing to the outside of the valve can be formed. Nevertheless, the valve is still balanced against pressure impacts.

The invention will be described in more detail in the following with reference to the attached drawing, wherein Figure 1 is an axial sectional view of the invention as applied to a two-way valve, and Figure 2 is an axial sectional view of the invention as applied to a three-way valve.

The spindle valve shown in Figure 1 of the drawing comprises a body 1 having a valve housing 2 and two connections 3, 4 communicating therewith. The valve further comprises a spindle 5 and valve disc 6 attached to one end of the spindle and interacting with a seal surface 7a of a flow opening 7 positioned in the valve housing for opening and closing said flow opening.

A plate-like counter piece 8 is positioned at the opposite end of the spindle, which counter piece forms a piston of a pressure medium cylinder of an actuator 9 which displaces the spindle. A cylindrical projection 10 extends from an end wall la of the body into the valve housing. This projection and the counter piece 8 together form said pressure medium cylinder. A connection opening 11 is provided in the end wall of the body for a pressure medium conduit communicating with a pressure medium source.

The valve disc is provided with a cylindrical sleeve 12 projecting towards the other end wall 1b of the body. A cylindrical projection 13 extends from this end wall of the body into the valve housing, into which projection the sleeve 12 extends axially slidably. A returning member of the actuator, i.e. a compression spring 14 tending to push the valve disc towards a closed position, is positioned within the sleeve between the valve disc and said end wall. The sleeve is pressed against the inner surface of the projection by means of a sealing 15 in a pressure-medium-proof manner.

The projection 10, the piston 8, the spindle 5, the valve disc 6, the sleeve 12 and the projection 13 are concentric with respect to each other, so that the spindle is axially displaceable under the guidance of the projections 10 and 13.

A surface 8a of the counter piece 8, on which surface the liquid pressure prevailing in the valve housing exerts an axial force F, equals in size with that surface 6a of the valve disc 6 on which the liquid pressure exerts a corresponding axial force F, so that the spindle is balanced and possible pressure impacts of the liquid do not cause an opening of the valve disc.

It is also noted that the actuator is wholly positioned within the valve housing and that the connection opening 11 is the only extension of the actuator from the valve housing to the outside of the body. This connection opening is easy to attach to an pressure medium conduit in an absolutely medium-proof manner. The valve housing can thus be closed quite hermetically, with the exception of the connections 3 and 4.

Figure 2 of the drawings shows a three-way valve according to the present invention.The valve body has a third connection 4', and the valve housing is provided with a second flow opening 7' having seal surface 7a'.

The counter piece 8 of the spindle forms a cylindrical sleeve 16 which terminates in a second valve disc 6' identical with the first valve disc 6 and interacting with said second flow opening 7'.

In 'h s embodiment, too, the actuator is wholly positioned within the valve housing, and the spindle including its valve discs is wholly balanced against pressure impacts.

The drawings and the desciption related thereto are only intended to illustrate the idea of the invention.

In its details, the spindle valve according to the invention may vary within the scope of the claims. Accordingly, the return spring and the pressure medium cylinder may chance places. It is liis possible in certain cases to position the return spring on the same side as the counter piece. Furthermore, the return spring can be replaced by a pressure medium cylinder. Also, it is possible to arrange the sleeve-like counter piece so that it surrounds the projection 10 externally instead of moving therewithin.

Claims

Claims:

1. A spindle valve for a pressurized flowing medium, comprising - a body (1) having at least two connections (3,4) and a valve housing (2) between the connections, - a spindle (5) mounted axially slidably on the body and provided with a valve disc (6) positioned within the valve housing, - an actuator (9) for axial displacement of the spindle between a closed position for closing one connection and an open position for opening said connection, - a counter piece (8) positioned within the valve housing (2) and attached to the spindle (5), said counter piece forming a moveable element of the actuator (9) positioned within the valve housing, c h a r a c t e r i z ed in - that an area (8a) of the counter piece (8), which area is exposed to a medium pressure acting in the axial direction of the spindle, is essentially equal to a corresponding area (6a) of the valve disc, and - that a returning member (14) of the actuator is mounted within the body and separated in a medium-proof manner from the valve housing.

2. A valve according to claim 1, c h a r a c t e ri z e d in that the counter piece (8) forms a piston of the actuator (9).

3. A valve according to claim 1 or 2, wherein the body is provided with three connections (3,4,4') communicating with the valve housing (2), and the valve housing is provided with two flow openings (7,7') alternately closed by valve discs (6,6'), c h a r a c t e r i z e d in that the counter piece (8) forms as a second valve disc (7') of the valve.

4. A valve according to claim 2, c h a r a c t e ri z e d in that an end wall (1a) of the body (1) extends axially into the valve housing (2) as a cylindrical projection (10) which forms a cylinder for the piston (8).

5. A valve according to claim 4, c h a r a c t e ri z e d in that an opposite end wall (lob) of the body (1) extends axially into the valve housing (2) as a cylindrical projection (13), and that the valve disc (6) is fastened to an axial sleeve (12) mounted axially slidably on said projection so that the sleeve and the projection form a medium-proof housing for the returning member (14).

6. A valve according to claim 5, c h a r a c t e ri z e d in that the returning member (14) is a compres sion spring.

7. A spindle valve for a pressurised flowing medium, such valve being constructed and arranged to operate substantially as hereinbefore described with reference to and as illustrated in either Figure of the accompanying drawings.