GB2150671A

GB2150671A - Control valve

Info

Publication number: GB2150671A
Application number: GB08430428A
Authority: GB
Inventors: Michael Betteridge
Original assignee: IMI Mouldings Ltd
Current assignee: IMI Mouldings Ltd
Priority date: 1983-12-02
Filing date: 1984-12-03
Publication date: 1985-07-03
Also published as: GB2150671B; GB8332305D0; GB8430428D0

Abstract

A valve for the control of fluid flow which has a passageway defined between an "O"-ring held within a body and a closure mechanism. the mechanism comprising: (i) a closure member which can be moved between an "open" and a "closed" position. (ii) a substantially cylindrical control porton adjacent the closure member and having longitudinal grooves therein and (iii) a substantially conical control portion having a longitudinally fluted outer surface with its broader cross-section adjacent the control portion so that the passageway cross- section is varied as the closure member moves from its closed to its fully open position. The grooves 16 in the cylindrical portion 15 help to prevent water hammer or noise. <IMAGE>

Description

SPECIFICATION Valves and mechanisms therefor This invention relates to valves and mechanisms therefor and more particularly to valves incorporating regulators to control the rate of flow of fluid passing through the valve.

In accordance with the invention, there is provided a valve having a body which defines an inlet and an outlet and a passageway therebetween, the valve also having a closure mechanism positioned on one end of an actuating spindle so that a closure member on the closure mechanism can be moved between a "closed" position in which the closure member engages a seat in the valve body and a "open" position in which no such engagement occurs, the closure mechanism further having:: i) a control portion mounted co-axially with respect to the spindle and having a substantially conical, generally longitudinally-fluted outer surface with its broader cross-section nearest the spindle and ii) a generally longitudianally grooved, substantially cylindrical portion situated between the conical portion and the spindle and the control portion being positioned relative to a resilient ring held within the vavle body so that the ring co-operates with the cylindrical portion of the closure mechanism in the closed position and during initial movement of the closure mechanism away from the closed position and the ring co-operates with the fluted conical portion only after such initial movement away from the closed position has been effected. The term conical used herein includes ' "frusto-conical".

In currently available valves, it is well known to use control portions having fluted conical shapes which engage with a resilient O-ring held with the valve body. At a selected position of the O-ring about the fluted portion the amount of fluid passing through the valve is determined by the pressure of the fluid and by the size of the passageway cross-section between the fluted portion and the O-ring and the rate of flow is kept substantially constant because increasing deformation of the O-ring about the fluted surface, and hence a narrowing of the passageway, is caused with an increasing pressure of fluid. It is important in valves used in water heaters and showers and the like having a predetermined electrical input to ensure a substantially constant flow to the heater chamber so as to enable the water issuing from the chamber to have a substantially constant temperature.

It is also known in currently available valves that an "on-off" closure member can be employed in conjunction with fluted conical control portions. In certain valves of this type, a cylindrical portion has also been included.

However, in such valves, the internal circumference of the O-ring provided in the body of the valve engages the cylindrical portion in the off or closed position and also during initial opening of the valve; as a result, the initial flow of fluid is irregular and tends to cause a "hammer" effect on the O-ring. In fact, constant fluid flow through the valve tends to occur only when the O-ring ceases to engage the cylindrical portion and engages the fluted conical portion.

In the valves of the invention, on the other hand, the resilient ring engages the generally cylindrical portion and the grooves which must be present its surface are present to ensure (and even encourage) positive and constant flow, albeit a relatively small amount, during initial opening of the valve, thereby preventing any "hammer" effect.

The cylindrical portion will generally have a diameter which is the same as or which is slightly larger than the maximum diameter of the fluted portion (including the flutes themselves). Preferably, the valves of the invention use a non-rising spindle and the closure mechanism comprises or is attached to a valve stem which is moved towards and away from the valve seat on rotation of the spindle.

The valves may be manufactured from metal or plasic material or a combination thereof.

In preferred valves, therefore, the spindle operates, when rotated, a closure mechanism which is attached to a valve stem and which comprises, closest to the stem, a closure member consisting of or incorporating a resilient washer (or similar) which can engage a valve seat in the valve body, a grooved cylindrical portion adjacent the closure member and a fluted conical portion adjacent the cylindrical portion and therefore furthest from the valve stem.

By way of example, to illustrate one embodiment of the invention, reference is now made to the accompanying drawings in which: Figure 1 shows a vertical section through a valve of the invention; Figure 2 shows a horizontal section through a cylindrical portion of the valve shown in Fig.

1.

Referring to the drawings, a valve comprises a body 1 defining an inlet 2 and an outlet 3 and a passageway 4 therebetween.

The valve has a non-rising spindle 5 held in position by, but allowed to rotate within, a bonnet 6 attached to the body 1 by means of engaging screw threads at 7. Rotation of the spindle 5 can be caused by rotation of a hand-wheel 8 which is fixed to the spindle 5 by means of inter-engaging grooves at 9 and a screw 10.

The spindle has a threaded bore 11, the threads of which engage corresponding threads on the exterior surface of a cylindrical valve stem 1 2 and rotation of the spindle 5 by means of hand-wheel 8 causes movement of the stem 12 within the bore 11.

The valve stem 1 2 has a stem extension 1 3 of hexagonal cross-section which co-operates with a hexagonal surface at the lower end of the bore 11. Rotation of the stem 1 2 about its longitudinal axis is thereby prevented but longitudinal movement of the stem 1 2 within the bore 11 is allowed on rotation of the spindle 5.

The stem 1 2 carries a closure mechanism comprising a resilient annular washer 14 mounted about the valve stem and abutting the extension 13, a cylindrical portion 1 5 having longitudinal grooves 1 6 therein (see also Fig. 2), and a longitudinally-fluted frustoconical portion 17, all of which are mounted co-axially with respect to the valve spindle.

The body 1 has fixedly attached thereto in the vicinity of the passageway 4 an annular portion 18, the top part of which defines a seat 1 9 against which the washer 14 can engage and an inner part which has a groove for receiving and retaining a resilient O-ring 20.

The closure mechanism as a whole clearly can be moved relative to the body 1 in general and to the O-ring 20 in particular by means of rotation of the hand-wheel 8 so as to vary the cross-sectional size of the passageway 4.

In the closed position, the lower side of washer 14 engages the seat 1 9 and completely closes the passageway 4 and the 0ring 20 is in tight engagement with the cylindrical portion 1 5. Initial movement of the closure mechanism away from the closed position causes displacement of the washer 14 away from the seat 1 9 but the O-ring remains in engagement with the cylindrical portion 1 5.

The grooves 1 6 in the cylindrical portion, however, encourages a certain amount of fluid to flow through the passageway 4; indeed, the grooves 1 6 encourage a small amount of flow.

Further movement of the closure mechanism towards the valve open position causes the cylindrical portion 1 5 to move out of engagement with the O-ring 20 and causes the fluted conical portion 1 7 to engage the 0ring. In the particular embodiment shown in the drawings, the conicity of the portion 1 7 is provided by having only alternate flutes decrease in cross-sectional size in a direction away from the cylindrical portion 1 5 whereas the other flutes do not decrease in size in this way. This is why the portion 1 7 shown in Fig.

1 gives the impression of being, but is not, cylindrical.

As the O-ring engages the fluted conical portion during progressive movement of the closure mechanism towards the open position, the amount of fluid flowing through the passageway 4 will increase due to the larger passageway cross-section between the conical fluted portion and the O-ring.

At any given position of the O-ring in relation to the fluted conical portion, however, any variation in fluid pressure will cause the passageway cross-section to change by means of variation in the position of the O-ring about the conical portion. Generally, the greater the pressure, the greater will be the engagement between the O-ring and the conical portion and the greater will be the presence of the 0ring due to its deformation, within the spaces between the flutes, thereby ensuring an essentially constant flow of fluid.

Claims

1. A valve having a body which defines an inlet and an outlet and a passageway therebetween, the valve also having a closure mechanism positioned on one end of an actuating spindle so that a closure member on the closure mechanism can be moved between a "closed" position in which the closure member engages a seat in the valve body and a "open" position in which no such engagement occurs, the closure mechanism further having:: i) a control portion mounted co-axially with respect to the spindle and having a substantially conical, generally longitudinally-fluted outer surface with its broader cross-section nearest the spindle and ii) a generally longitudinally grooved, substantially cylindrical portion situated between the conical portion and the spindle and the control portion being positioned relative to a resilient ring held within the valve body so that the ring co-operates with the cylindrical portion of the closure in the closed position and during initial movement of the closure mechanism away from the closed position and the ring co-operates with the fluted conical portion only after such initial movement away from the closed position has been effected.

2. A valve according to Claim 1, in which the cylindrical portion has a diameter which is the same as or which is slightly larger than the maximum diameter of the fluted portion.

3. A valve according to Claim 1 or Claim 2 in which the spindle operates, when rotated, a closure mechanism which is attached to a valve stem and which comprises, closest to the stem, a closure member consisting of or in-corporating a resilient washer (or similar) which can engage a valve seat in the valve body, a grooved cylindrical portion adjacent the closure member and a fluted conical portion adjacent the cylindrical portion and therefore furthest from the valve stem.

4. A valve according to Claim 1 substantially as described herein with reference to Fig. 1 or Fig. 2.