WO1996014529A1

WO1996014529A1 - Diaphragm valve

Info

Publication number: WO1996014529A1
Application number: PCT/NL1995/000373
Authority: WO
Inventors: Robertus Thimoteus Baars; Martinus Hubertus Nicolaas Van Den Berg
Original assignee: Dsm N.V.
Priority date: 1994-11-07
Filing date: 1995-10-30
Publication date: 1996-05-17
Also published as: NL9401848A; EP0828959A1; AU3817695A

Abstract

Control valve comprising a body (1) and a closing element (2) movable between an open and a closed position in a chamber bounded by the body, with the body having at least two flow openings (4a, 4b, 5a, 5b) to the chamber, and with an elastic diaphragm being present between the closing element and the body, which overlaps the flow openings and which is operated by the closing element in such a way that, when the closing element is in the open position, a flow channel is present between the two flow openings, which channel is bounded by the body and the diaphragm.

Description

DIAPHRAGM VALVE

The invention relates to a control valve comprising a body and a closing element movable between an open and a closed position of the valve and present in a chamber bounded by the body, with the body having at least two flow openings to the chamber.

A control valve of this type is disclosed in NL-A-7613145.

The aforementioned patent application describes a control valve whose closing element is cylindrical. A channel that runs through the closing element at a right angle to its longitudinal axis can be placed between two flow openings by rotating the closing element. O-rings are provided at each end of the valve to prevent leakage past the valve to the outside of the valve.

A disadvantage of such a valve is that wear of the closing element may well cause leakages between the flow openings or, particularly if the O-rings have been subject to wear, between one or more flow openings and the outside of the valve.

The object of the invention is to provide a control valve that presents the aforementioned disadvantage to at least a much lesser extent. This objective is accomplished in that the control valve of the invention contains an elastic diaphragm between the closing element and the body, which overlaps the flow openings and which is operated by the closing element in such a way that, when the closing element is in the open position, a flow channel is present between the two flow openings, which channel is bounded by the body and the diaphragm. Since the diaphragm is operated by the closing element, the diaphragm is pushed against the body when the valve is in the closed position so that no flow channel is present in this position. In the open position the pressure of the fluid passing through the control valve results in elastic deformation of the diaphragm such that the flow channel is formed. It is important here that the diaphragm be so attached that the flow channel is bounded by the body and the diaphragm.

In this manner, a control valve is obtained which is substantially less susceptible to wear. Furthermore, the control valve of the invention when in closed position affords very tight shut-off of the flow openings and a good seal to the outside of the valve when in open or closed position whilst the closing element can nevertheless be easily moved between the open and closed positions.

A further advantage of the control valve of the invention is that the fluid passing through the valve does not come into direct contact with the closing element, so that lubricants may be present between the closing element and the body without the lubricants contaminating the fluid flowing through the valve.

The surface of the closing element preferably includes a recessed area to accept the diaphragm when the valve is in the open position.

In this manner a valve of simple construction is obtained, the diaphragm in which is easy to operate by moving the closing element along the diaphragm.

Furthermore, even when the valve is in the open position, the diaphragm is supported at the flow channel by the closing element so that the diaphragm is less prone to wear or damage.

The recessed area may consist of a recess in the surface of the closing element. Alternatively, the closing element may have a projection, such as a stud, on its surface. In this case, the recessed part of the surface of the closing element is the part adjacent to the projection. The control valve of the invention is suitable for controlling gas and liquid streams. Furthermore, the control valve of the invention is suitable for being incorporated in water taps such as those commonly used in kitchens and bathrooms. The control valve may be so designed that the closing element translates along its longitudinal axis or rotates about its longitudinal axis between the open and closed positions in the body. The closing element preferably is cylindrical. The flow rate of the liquid stream or gas stream which the control valve allows to pass depends on inter alia the position of the closing element relative to the flow openings in the body and the shape of the recessed part in the surface of the closing element. Preferably, the recessed area in the surface of the closing element is so designed that, as the closing element moves with uniform velocity from the closed position to the open position, the flow rate increases gradually, more preferably at a constant rate, over the range between the two positions. In this way, a control valve is obtained with which the flow rate can be controlled very accurately.

The diaphragm is preferably compressed between the body and the closing element. This can readily be accomplished inasmuch as the distance between the body and the closing element is smaller than the thickness of the diaphragm. This ensures very tight shut-off of the control valve. It is of importance that the diaphragm not be excessively compressed, otherwise the closing element can only move in the body in the face of high friction. It is preferred for the diaphragm to be compressed between the closing element and the body to 90 to 98 % of the original thickness of the diaphragm.

It is preferred for the body of the control valve of the invention to contain two pairs of flow openings and for the closing element to possess one or more, preferably two, recessed areas on its surface so that, on moving the closing element in a first direction of motion a flow channel is formed between the diaphragm and the body between each pair of flow openings and by moving the closing element in a second direction of motion, the flow channel between one pair of flow openings opens further while simultaneously the flow channel between another pair closes further.

Such a control valve is highly suitable for use as a component of a mixing valve for hot and cold water as used in, for instance, kitchens and bathrooms. In this way, a mixing valve is easily obtained which can be operated with one head and allows the overall flow rate to be adjusted in a fixed ratio between the flow rates of hot and cold water.

It is preferred for the diaphragm to be manufactured from a chemically cross-linked elastomer because such an elastomer exhibits little or no creep and the diaphragm retains its original shape in unloaded condition, regardless of, for instance, prolonged compression of the diaphragm between the body and the closing element. Furthermore, the choice of material for the closing element is determined by inter alia the fluid passing through the valve, since the closing element must be resistant to the fluid, and the temperature at which the valve is used. If the valve forms part of a water tap, EPDM is a highly suitable elastomer for fabrication of the diaphragm.

The body can in theory be manufactured from any customary material such as a metal, a thermoset or a thermoplastic. As in the case of the diaphragm, the choice of material is determined by inter alia the fluid passing through the valve and the temperature at which the valve is used. If the valve forms part of a water tap, highly suitable materials for fabrication of the body are: copper, acrylonitrile butadiene styrene copolymers (ABS), polycarbonate (PC), thermoplastic polyester (PET, PBT) or thermosetting compounds based on an epoxy resin, a polyurethane resin or an unsaturated polyester resin. It is preferred for the body to be injection moulded from a thermoplastic. The closing element can in theory be manufactured from the same material as the body. However, since the closing element does not come into contact with the fluid passing through the valve, the closing element need not be resistant to the fluid. The valve can be fashioned into a plurality of specific embodiments depending on, for instance, its service. The valve may, for instance, form part of a chemical process plant, be included in a petrol line, be inserted in a liquid or gas metering system and so forth. The closing element can readily be operated in that it is connected to a hand-operated head or handle or may be positioned with, for example, a controller-operated stepping motor, so that the flow rate of the fluid passing through the valve can be controlled accurately and continuously.

The valve preferably forms part of a water tap.

The control valve of the invention is also highly suitable for use as a component in a flushing cistern for a lavatory pan. In that case, the valve can be operated by the float of the cistern. The points at which the valve opens and closes can be accurately determined depending on the float position.

The invention is illustrated by the drawing, without being limited thereto.

Fig. 1 is a schematic representation of a section through the control valve of the invention along the longitudinal axis of the closing element in closed position.

Fig. 2 is a schematic representation of the control valve according to Fig. 1 except that it is shown here in open position.

Fig's 3 and 4 are schematic representations of the A-A planes of the control valve as shown in Fig's 1 and 2, respectively.

Fig. 5 is a schematic representation of a section through the control valve perpendicular to the longitudinal axis of the closing element. The valve may be integrated into a mixing valve that is operated by a single head.

Fig's 6a-6c are schematic representations of sections through plane B-B of the control valve in Fig. 5.

The control valve in Fig's 1 and 2 comprises a body 1, a cylindrical closing element 2 and a diaphragm 3. The body has two flow openings 4 and 5 to the chamber of the body. One of the flow openings may be connected to a supply line, the other flow opening may be connected to a return line. The closing element has a recessed area in its surface in the form of a recess 6 along its surface. Fig's 3 and 4 are schematic representations of a control valve along the plane A-A in Fig's 1 and 2, respectively, with the body 1, the cylindrical closing element 2, the diaphragm 3 which is located in the body at two ends 31 and 32. Flow opening 4 and recess 6 along the surface of the closing element are also shown. It will be evident from the shape of the recess that the flow channel gradually becomes larger as the closing element is moved from the closed to the open position, thus allowing accurate flow control. In Fig's 1 and 3, the closing element 2 pushes the diaphragm 3 against the body so that both flow openings are closed by the diaphragm. In Fig's 2 and 4, the closing element 2 has rotated about its longitudinal axis in the direction indicated by the arrow a in Fig's 1 and 3 and the recess 6 is located between the flow openings 4 and 5 so that the diaphragm 3 can flex so that a flow channel forms between the body and the diaphragm.

The control valve in Fig. 5 comprises a body 1, a cylindrical closing element 2 with a recess 6 and a diaphragm 3. The body has two pairs of flow openings 4a, 5a and 4b, 5b to the chamber of the body. Supply lines for hot and cold water can be connected to flow openings 4a and 5a, respectively, so that the valve may form part of a mixing valve. In that case, the water may be supplied through the flow openings 4b and 5b to a mixing system known for mixing valves.

If the closing element is rotated about its longitudinal axis in the direction of arrow a in Fig. 5 and Fig. 6a, one of the flow channels (6a) is opened further whilst the other flow channel (6b) closes further. This makes it possible to adjust the ratio between the warm and cold water flow rates. By translating the closing element along its longitudinal axis in the direction of arrow b, as shown in Fig. 6c, the overall water flow rate is adjusted in a fixed ratio between the warm and cold water flow rates.

Claims

C A I M S

1. Control valve comprised of a body and a closing element movable between an open and a closed position of the valve and present in a chamber bounded by the body, with the body having at least two flow openings to the chamber, characterized in that an elastic diaphragm is present between the closing element and the body, which overlaps the flow openings and which is operated by the closing element in such a way that, when the closing element is in the open position, a flow channel is present between the two flow openings, which channel is bounded by the body and the diaphragm.

2. Control valve according to Claim 1, characterized in that the closing element has a recessed area in its surface to accept the diaphragm when in open position.

3. Control valve according to Claim 1 or 2, characterized in that the closing element rotates about its longitudinal axis in the body between the open and closed positions.

4. Control valve according to any one of Claims 1-3, characterized in that the closing element translates along its longitudinal axis in the body between the open and closed positions.

5. Control valve according to any one of Claims 1-4, characterized in that the recessed area in the surface of the closing element is so designed that, as the closing element moves with uniform velocity from the closed position to the open position, the flow rate increases gradually over the range between the two positions.

6. Control valve according to any one of Claims 1-5, characterized in that the diaphragm is compressed between the closing element and the body to 90 to 98 % of the original thickness of the diaphragm.

7. Control valve according to any one of Claims 1-6, characterized in that the body contains two pairs of flow openings and in that the closing element possesses one or more recessed areas in its surface so that, on moving the closing element in a first direction of motion a flow channel is formed between the diaphragm and the body between each pair of flow openings and by moving the closing element in a second direction of motion, the flow channel between one pair of flow openings opens further while simultaneously the flow channel between another pair closes further.

8. Control valve according to any one of Claims 1-7, characterized in that the valve forms part of a domestic water tap.

9. Cistern for a lavatory pan, characterized in that the cistern incorporates a control valve according to any one of Claims 1-7.