GB2039344A - Flow regulating valve - Google Patents

Abstract

A flow regulating valve incorporates a variable area pressure reducing restriction and a flow regulator responsive to a pressure difference existing across said restriction so as to maintain a constant rate of fluid flow despite variations of supply pressure. The variable restriction is defined by an orifice 22 in combination with a movable plug member 15 which is adjustable by means of a shaft 5 which also operates a stop valve. A sleeve 11 is movable by means of a diaphragm 9 and co- operates with an annular channel 24 to maintain a constant rate of flow in response to variations in the pressure difference on opposite sides of the orifice 22. <IMAGE>

Description

SPECIFICATION Flow regulating valve This invention relates to a flow regulating valve which is intended primarily, but not exclusively for use with domestic water heating appliances of the so-called "instantaneous" type in which heat is supplied at a known rate to water flowing continuously through the appliance. The rise in temperature of the water delivered from the appliance is accordingly inversely related to the rate of flow.

The object of the present invention is to provide a simple flow regulating valve which is readily adjustable by the user to regulate the rate of water flow at any desired value within a range of operational values so as to provide hot water at a selected temperature, the valve then maintaining the desired rate of flow substantially independently of variations in supply pressure.

Whilst the invention will be described in relation to a valve for controlling the flow of water, it will be appreciated that the valve may, in principle, be used with other fluids, and that its application is not restricted solely to the supply of fluids to heaters.

According to the invention a flow regulating valve comprises a body defining a fluid passageway extending from an inlet to an outlet, a manual stop valve in said passageway, a manually adjustable flow controlling a restriction in said passageway for varying the rate of flow of a fluid through the passageway, and a flow regulator responsive to a pressure difference existing across said restriction and operative to maintain the rate of fluid flow constant at the rate determined by the restriction despite variations in the pressure of fluid supplied to the inlet.

Preferably, the restriction is adjusted by means of a movable member which is also arranged to operate the stop valve, and the stop valve is preferably itself arranged downstream of the restriction.

Conveniently, the flow regulator comprises a sleeve valve coupled to a diaphragm which divides a chamber into two compartments, one of which is in communication with the passageway at a position immediately upstream of the restriction, and the other of which is in communication with the passageway at a position immediately downstream of the restriction.

The body is conveniently generally of cylindrical form with the passageway extending axially therealong, with the inlet and the outlet extending laterally adjacent to opposite ends of the passageway. The chamber in which the diaphragm is disposed may be arranged adjacent to the inlet, with the diaphragm extending generally transversely relative to the axial passageway, and the stop valve may be operable by means of an axial shaft which extends out of the passageway at the end opposed to the diaphragm chamber. The restriction is conveniently defined by means of a fixed orifice and a shaped plug which is movable axially into and out of the orifice.

These and other features of the invention will now be described by way of example with reference to the accompanying drawing which shows one embodiment of valve in transverse section with the flow regulator illustrated in its two extreme positions.

As shown in the accompanying drawing, the valve comprises a generally cylindrical body 1 having an axially extending passageway which is divided by transverse walls la and 1 b into three chambers B, D, and E. A lateral inlet 7 communicates with chamber B by way of an annular channel 24, and a lateral outlet 8 communicates directly with chamber E.

At the inlet end of the body, a cover plate 2, in combination with the adjacent end of the body, defines a further chamber which is divided into two compartments A and C by means of a flexible diaphragm 9. The diaphragm 9 has a central stiffening plate 10 and has a sleeve member 11 secured thereto by means of a stud 20. The sleeve member 11 fits slidably within chamber B and the end 25 of the sleeve member co-acts with the annular channel 24 to regulate flow of fluid from the inlet 7 to the interior of chamber B.

The dividing wall la is formed with a central orifice 22 through which fluid flows from chamber B into chamber D, and the dividing wall lb is similarly formed with an orifice 27 through which fluid flows into chamber E.

A valve shaft 5 which extends axially into the chamber E is carried by a boss 4 at the end of the passageway opposed to the diaphragm chambers The shaft 5 is secured by a gland nut 17 which bears upon packing 16 to form a fluid-tight seal. The shaft 5 carries a washer plate 13 with a washer 14 which is adapted to seat against the dividing wall 1b around the orifice 27 so as to act as a stop valve.

The washer plate 13 includes a stem 13a which carries a tapered plug 15 adapted to enter the orifice 22 in dividing wall la and form in conjunction therewith a pressure reducing restriction in the passageway. Thus, by means of a control knob 6 carried at the outer end of the shaft 5, the plug 15 can be set relative to the orifice 22 to provide a selected rate of flow of fluid through the valve. As a result of the pressure loss across the restriction, the pressure in chamber B will be greater than that in chamber D.

A passageway 23 extends between chamber D and compartment C of the diaphragm chamber so that the pressure in compartment C is substantially equal to that in chamber D. Likewise, a bore 21 extends through the stud 20 at the end of the sleeve member 11 to place the interior of chamber B in communication with compartment A of the diaphragm chamber, so that the latter is substantially at the same pressure as the former. Thus, the diaphragm 9 is subject to a nett force which is dependent on the pressure difference which exists at any time across the restriction afforded by orifice 22 and plug 15. A spring 12 is provided within the chamber B to bias the sleeve member 11 towards its fully open position in which the stud 20 contacts the cover plate 2. The latter may carry a slidable plunger 30 which projects into the diaphragm compartment through a boss 29.

A stop member 31 on the plunger limits movement of the latter into the diaphragm compartment, and when the sleeve member 11 is in its fully open position, stud 20 displaces the plunger 30 outwardly.

The plunger 30 may be arranged, for example, to interrupt the power supply to an electric heater with which the valve is associated when the rate of flow of fluid through the valve falls to such a level that the plunger 30 is displaced to its outermost position.

In use, when the valve is connected between a water supply and a water consuming appliance, and the stop valve is closed, since there is no flow of water from chamber B to chamber D, there is no pressure drop across the restriction defined by the orifice 22 and plug 15, and as a result the sleeve member 11 is biased by the spring 12 into the position shown in the right-hand half of the accom panying drawing, so that the stud 20 is in contact with the cover plate 2 and the plunger 30 is displaced outwardly from the diaphragm chamber.

When the manual stop valve is opened to allow fluid to flow through the valve, a pressure drop is immediately established across the restriction, and the manual setting of the shaft 5 determines the rate of flow of fluid to the appliance. The assembly of sleeve member 11 and diaphragm 9 then floats under the dynamic equilibrium of opposing forces, namely the thrust of the spring 12 and the force applied to the diaphragm due to the pressure existing in compartment C on the one hand, and the opposing force applied to the diaphragm from the pressure existing in compartment A. The sleeve member 11 thus attains an equilibrium position and the rate of flow of fluid through the valve is determined by the setting of plug 15.If the supply pressure changes, this will cause an instantaneous change in the rate of flow through the pressure reducing restriction, and this in turn will cause a change in the pressure drop across the restriction.

The diaphragm will respond to this change in pressure drop to move the sleeve member 11 to a new position of equilibrium in which the pressure drop across the restriction returns to its previous value, so that the overall rate of flow of fluid through the valve is quickly restored to its original setting.

It will be appreciated that if the supply pressure at the inlet 7 increases, the increased flow of fluid through the pressure restriction will result in an increase of the pressure drop between chambers B and D so that the pressure difference between compartments A and C will increase, with the result that the diaphragm will move the sleeve member 11 inwardly so as to reduce the rate of flow until the initial conditions are re-established. In the same manner, if the pressure at the inlet 7 is decreased, the pressure difference between compartments A and C will also be decreased, and the sleeve member ii will move outwardly so as to increase the rate of flow from the channel 24 into chamber B.

Thus, within the limits of movement permitted to sleeve member 11, the valve will maintain a constant rate of flow at the outlet 8, and the rate of flow can be selected by adjustment of the handle 6 to set the plug 15 in any desired position of adjustment relative to the orifice 22.

Although the end 25 of the sleeve member 11 is shown as extending perpendicularly transverse to the axis of the sleeve member, it will be appreciated that if desired it may be inclined obliquely relative to such axis, or shaped in some other way so as to provide for smooth regulation of flow in response to axial movements of the sleeve member 11. Indeed, instead of utilising the end of such a sleeve to regulate flow of fluid from the recess 24 into the interior of the chamber B, it would alternatively be possible to make the sleeve 11 of greater length and form therein a circumferentially extending wedgeshaped slot which is arranged to register with the recess 24 to a greater or lesser extent for the purposes of regulation.

Where the valve is used in association with a fluid fuel consuming appliance, the plunger 30 may be connected in such a manner as to operate a shut-off valve in order to prevent the supply of combustible fluid in response to the establishment of a rate of flow through the valve sufficiently low to cause the sleeve member 11 to adopt the position shown in the right-hand side of the accompanying drawing. Alternatively, provision for the plunger 30 may be omitted entirely from the valve so that some other form of, external safety device can be employed if necessary.

It will be appreciated that the valve is not intended exclusively for use in connection with heating appliances, but may be utilised in any circumstances where a regulated rate of fluid delivery is required.

Accordingly, the valve could be used to ensure a constant rate of flow from a storage tank when the pressure head of liquid therein falls continuously as it empties.

Claims (10)

1. Aflow regulating valve comprising a body defining a fluid passageway extending from an inlet to an outlet, a manual stop valve in said passageway, a manually adjustable flow-controlling restriction in said passageway for varying the rate of flow of a fluid through the passageway, and a flow regulator responsive to a pressure difference existing across said restriction and operative to maintain the rate of fluid flow constant at the rate determined by the restriction despite variations in the pressure of fluid supplied to the inlet.

2. A valve according to Claim 1 wherein said adjustable restriction comprises an orifice formed in a transverse wall extending across said passageway and a plug member which is movable relative to said orifice so as to define therewith an opening of variable cross-sectional area.

3. A valve according to Claim 2 where in the plug member is carried by an operating member which also carries a valve element of said stop valve.

4. A valve according to any one of the preceding claims wherein the stop valve is arranged downstream of said restriction.

5. A valve according to any one of the preceding claims wherein the flow regulator comprises a sleeve valve coupled to a diaphragm which divides a chamber into two compartments, one of which is in communication with the passageway at a position immediately upstream of the restriction, and the other of which is in communication with the pas sageway at a position immediately downstream of the restriction.

6. A valve according to any one of the preceding claims wherein the body is of generally cylindrical form with the passageway extending axially therealong, and with the inlet and the outlet extending laterally adjacent to opposite ends of the body.

7. A valve according to ClaimS, as appendantto Claim 5, wherein the chamber in which the diaphragm is disposed is arranged adjacent to the inlet, with the diaphragm extending generally transversely relative to the axial passageway.

8. A valve according to Claim 7 wherein the stop valve is operable by means of an axial shaft which extends out of the passageway at the end opposed to the diaphragm chamber.

9. Aflow regulating valve comprising a body defining a fluid passageway extending from an inlet to an outlet, a manually adjustable flow-controlling restriction in said passageway for varying the rate of flow of a fluid through the passageway, and a flow regulator responsive to a pressure difference existing across said restriction and operative to maintain the rate of fluid flow constant at the rate determined by the restriction despite variations in the pressure of fluid supplied to the inlet.

10. Aflow regulating valve substantially as hereinbefore described with reference to and as shown in the accompanying drawing.