GB2051316A

GB2051316A - Valves

Info

Publication number: GB2051316A
Application number: GB8018534A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-06-26
Filing date: 1980-06-05
Publication date: 1981-01-14

Abstract

A valve for use for example in a domestic water tap, comprises a manually operated stem portion (2), a plug member (12) arrayed to move in a lengthwise direction with the stem portion to open or close the valve, said plug member having a head portion (12) with a conical or frusto-conical surface (14) projecting beyond said stem portion, and a fluid inlet defined by an annular valve seat portion having a continuous frusto-conical seating surface (20) with the same angle of inclination as that of the plug member head portion with respect to the axial centre line of said plug member, the construction and arrangement being such that the inlet flow of fluid through the valve seat portion is co-axial with the plug member centre line and is controlled by the distance between the confronting conical or frusto-conical surfaces (14, 20) when the valve is in a closed condition, the flow being stopped by a continuous zonal band (A) of contact between said confronting surfaces, upon the occurrence of which contact, rotation of the plug member (12) with the stem portion (2) immediately ceases. <IMAGE>

Description

SPECIFICATION Valves The invention is concerned with improvements in or relating to valves for controlling fluid flow.

Valves according to the invention are suitable for use in taps or stop-cocks for a water supply, but it will be appreciated that the invention is not limited in this respect. It is customary to construct water taps or faucets with a rotatable member which forces a plunger into contact with a valve seat to close off the supply inlet. Conventionally, a stiffly resilient washer is provided, which when worn, requires replacement to avoid wastage of water. Many attempts have been made to avoid this inconvenience and to provide a so-called washerless tap. These attempts have hitherto met with limited success.

The present invention provides a valve for controlling a fluid flow, comprising a valve stem portion capable of helical rotation within a valve body member so as to partake of movement in a length-wise direction thereof, a valve plug member arranged to move in said lengthwise direction with the stem portion in a valve-closing movement, said plug member comprising a head portion with a conical or frusto-conical surface projecting beyond said stem portion, and a fluid inlet defined by an annular valve seat portion having a continuous frusto-conical seating surface with the same angle of inclination as that of the plug member head portion with respect to the axial centre line of said plug member, the construction and arrangement being such that the inlet flow of fluid through the valve seat portion is co-axial with the plug member centre line and is controlled by the distance between the confronting conical or frusto-conical surfaces, when the valve is in a closed condition the flow being stopped by a continuous zonal band of contact between said confronting surfaces, upon the occurrence of which contact, rotation of the plug member with the stem portion immediately ceases.

Although if the plug member head portion and the valve seat portion are manufactured with precision accuracy, the two portions may be made of steel, brass or any other suitable metal or alloy, it is often considered unduly expensive to produce on a commercial scale large quantities of precision-made articles for this type of merchandise. Therefore, it will be found convenient if one of the portions is made, for example, from hard, but slightly compressible, plastics materials.Consequently, the head portion of the plug member may be, for example, nylon, or some other material having similar properties including non-absorbence of water and preferably have dimensional stability over the water temperature range normally encountered, say 2 0--900 C. The use of nylon, for example, gives a satisfactory performance at pressures at which a conventional washer in a valve would disintegrate.

The head portion of the plug member may be frusto-conical, having a flat or substantially flat end surface against which the inlet flow of fluid, in the present example, water, impinges. In a valveopening operation, the valve stem portion is rotated in order to cause it to move in a direction away from the valve seat portion. Pressure of water in the inlet then lifts the plug member until the valve is closed again.

Conveniently the plug member may also comprise a rod portion which is received in a loose fit in a bore axially formed in the valve stem portion. This tends to help maintain the plug member in co-axial alignment with the valve seat portion during a valve closing operation. The rod portion will be a loose fit both to facilitate the cessation of rotation of the plug portion with the stem portion when contact is made between the confronting surfaces, and to allow a degree of selfcentring to occur as the plug member approaches the valve seat portion.

The rod portion will advantageously be of such a length that, even in the fully open position of the valve, the rod portion still remains partly received within the bore. Indeed, in certain countries, regulations laid down by the water authorities call for the plug member or its equivalent to be positively retained by the stem member. To comply with these regulations, the rod portion may be held in a non-gripping but captive manner in the bore.

Although the pitch of the helical (or screw) movement of the plug portion with respect to the stem portion may vary, it is not intended to change the value of this measurement from that which is standard on most valves and taps of this type. It has been found, therefore, that a suitable angle of inclination of the frusto-conical confronting surfaces from the centre line axis of the plug member may be in the range 120--200, a preferred angle being 150. Experience has shown that this range gives optimum flow rates in use, and a satisfactory zone of contact between the confronting surfaces which is at least 5 mm wide.

It will be appreciated that the invention is applicable not only to purpose-made valves but also to produce a conversion kit suitable for use to adapt existing washered taps and valves. This kit may include a plug member to replace the washer-bearing plunger and a valve seat insert receivable in the mouth of the inlet pipe, where this is axially in line with the operating stem portion and plug member.

There will now be described examples of valves according to the invention. It will be understood that the description, which is to be read with reference to the drawings, is given by way of example only and not by way of limitation.

In the drawings:- Figure 1 is a side elevational view, partly in cross section, of a first example according to the invention.

Figure 2 is a similar view of an alternative example; Figure 3 is a side elevational view of the parts shown in Figure 1 incorporated into a domestic water tap; Figure 4 is a fragmentary view of a portion of Figure 3, to an enlarged scale; and Figure 5 shows an alternative from a plug member.

Figure 1 shows a stem portion 2 of a valve for use in a domestic water tap, which stem portion is externally threaded at 4 to receive a valve body member (shown at 6 in Figure 3). An axial bore 8 is provided within the threaded portion 4, in which bore is received a rod portion 10 of a plug member 12. The rod portion is a loose fit in the bore that is in the present example, having a tolerance of 0.01 mm.

The plug member 12 comprises a head portion which is frusto-conical in configuration, having a surface 14, inclined at an angle of 15 to the axial centre line of the member 12, and a flat end surface 1 6. A water inlet pipe 1 8 has a lip portion having a surface 20 which is shaped to complement the angle af inclination of the surface 14 of the plug member 12. When the plug member is fully inserted in the lip portion, there is a wide continuous zonal band of contact A having a depth x, which in the present example is equivalent to a contact over a band 5 mm wide, measured in the axial direction.

Figure 2 shows identical parts to those shown in Figure 1 with the same references, the only difference being that, in order to comply with certain water authority regulations for instance, an annular groove 22 is provided in the rod portion 10', so that a projection 24 on the inside of the bore 8 engages with the groove to hold the plug member 12 in a non-gripping but captive manner.

Figure 3 shows the valve parts of Figures 1 or 2, assembled with the valve body member 6 in a tap housing, shown in chain-dotted lines at 26.

The lower portion of housing 26 is firmly secured upon the valve body member and includes a spout 28 through which water leaves the tap when the plug member 12 rises during the movement of the valve to the open position.

The frusto-conical lip surface 20 comprising the valve seating portion of the tap is shown in the present example as forming part of a brass insert secured in the inlet pipe mouth portion 18. While water traveling in an upward direction thus impinges upon the flat end surface 1 6 of the member 12, it may be preferred to employ a member 12 having a conical head portion 30 having an apex 31 which faces the flow of incoming water.

When the valve is being closed, the smooth entry of the member 12 into the valve seat portion defined by lips 20, is facilitated by the chamferring of the leading edge on the inside rim thereof at 32 as shown in Figure 4. As soon as there is contact between the surface 14 and 20, the plug member, which has been rotating with the stem portion 2, ceases to do so. Continued manual turning of the stem 2 causes the plug member to contact the surface 20 in a watertight manner, but because there is no rotary movement between the surfaces 14 and 20, no appreciable wear occurs between these surfaces, thus obviating the inconvenience of leakages with a subsequent need to change the washer, as is necessary in a conventional domestic water tap.

Claims

1. A valve for controlling a fluid flow, comprising a valve stem portion capable of helical rotation within a valve body member so as to partake of movement in a length-wise direction thereof, a valve plug member arranged to move in said lengthwise direction with the stem portion in a valve-closing movement, said plug member comprising a head portion with a conical or frustoconical surface projecting beyond said stem portion, and a fluid inlet defined by an annular valve seat portion having a continuous frustoconical seating surface with the same angle of inclination as that of the plug member head portion with respect to the axial centre line of said plug member, the construction and arrangement being such that the inlet flow of fluid through the valve seat portion is co-axial with the plug member centre line and is controlled by the distance between the confronting conical or frusto-conical surfaces, when the valve is in a closed condition the flow being stopped by a continuous zonal band of contact between said confronting surfaces, upon the occurrence of which contact, rotation of the plug member with the stem portion immediately ceases.

2. A valve as claimed in claim 1 wherein the head portion of the plug member is frusto-conical and has a flat or substantially flat end surface against which the flow of fluid through the inlet impinges.

3. A valve as claimed in either one of claims 1 and 2, wherein the valve plug member further comprises a rod portion, said valve stem member having an axially arranged bore to receive said rod portion in a loose fit.

4. A valve as claimed in claim 3, wherein the rod portion is held in a non-gripping but captive manner in the bore so that the plug member moves in said lengthwise direction with the stem portion during a valve-opening movement, irrespective of the pressure of fluid entering the inlet.

5. A valve as claimed in any one of the preceding claims, wherein the plug member is hardly compressible plastics material.

6. A valve as claimed in claim 1 wherein the angle of inclination is in the range of 120 to 200 with respect to the axial centre line of the plug me.mber.

7. A valve as claimed in claim 1, wherein the width of said continuous zonal band is not less that 5 mm.

8. A valve for controlling a fluid flow, constructed and arranged substantially as hereinbefore described with reference to and as shown in a) Figures 1, 3 and 4; b) Figure 2; c) Figure 5 Of the drawings.