GB2089939A

GB2089939A - Pressure Regulator

Info

Publication number: GB2089939A
Application number: GB8040219A
Authority: GB
Original assignee: TRINITY PUMPS Ltd
Current assignee: TRINITY PUMPS Ltd
Priority date: 1980-12-16
Filing date: 1980-12-16
Publication date: 1982-06-30
Also published as: GB2089939B

Abstract

The pressure regulator comprises a housing within which an inlet chamber 3 and an outlet chamber 5 are located. A control port 11 provides communication between the chambers and is defined between cooperating parts of the housing and a piston 15, the piston extending through both chambers and having portions 17, 19 of different diameters which are slidably received in complementary bores 21, 23 in the housing. The piston presents an increased surface area to the fluid within said outlet chamber 5 such that the fluid entering said chamber acts to urge the piston into a position to close the control port. Spring means act on the piston to oppose said fluid action to maintain the control port in an open condition consistent with the pressure required at the outlet of said chamber 5. Drain passages (29, 21) extend from the bores (21, 23) to pressure control means (33) for equalising the load due to the pressures on opposite ends of the piston (15) which result from leakage. <IMAGE>

Description

SPECIFICATION Improvements Relating to Pressure Regulators The present invention relates to a pressure regulator for use in controlling the pressure of a liquid passing therethrough.

In particular the present invention relates to a pressure regulator of the type described in our copending British Patent Application No.

7923465; wherein a piston having different diameter regions joined by a waisted portion, is slidably located in a regulator housing, a first annular chamber surrounding one region of the piston and a second annular chamber surrounding the greater diameter regiontof the piston. The chambers are interconnected by a control port which co-operates with the piston, the first chamber being connected to an inlet and the second chamber to an outlet of the regulator. The piston is spring biassed towards an open position and, in use, the liquid passing through the regulator acts upon the waisted portion to move the piston towards a position wherein the piston closes the control port. The piston attains an equilibrium position defining a particular through flow cross-section through the control port, thus determining at all times a substantially constant outlet pressure.

In a valve of this type the piston is also slidably received In complimentary diameter bores in the regulator housing. As expected leakage of the liquid passing through the regulator occurs between the piston and the associated bores. To reduce this leakage to a minimum various types of seals have been used, the main criterion for the seals besides sealing, being that they only minimally hinder the sliding movement of the piston. One seal was in the form of an O-ring with a PTFE covering ring to reduce friction. This seal was perfectly adequate during continual use after an initial period of bedding-in each time liquid flow commenced. However during the initial period of flow considerable leakage may occur between the piston and bore walls.To avoid pressure building up in the bores due to leakage past the piston, the bores in the regulator described in our copending British Patent Application No. 7923465, are provided with outlet ports which vent to the atmosphere.

However, leakage of liquid via these outlet ports is clearly undesirable.

A further problem or rather disadvantage of the above described regulator is that if connected, for example, in a water supply line, when the tap or water cock connected to the regulator outlet, is fractionally, or partially, opened the pressure maintained on the outlet side of the regulator holds the regulator closed, or substantially closed, until the tap or water cock is sufficiently open to permit full flow at the regulated pressure. Thus there can be little control of the intermediate flow of water as is often desired, the regulator basically only allowing virtually full or low flow.

The regulator of the present invention seeks to overcome the above problems and disadvantages.

According to the present invention there is provided a pressure regulator comprising a housing within which a pair of chambers are located, one of the chambers having an inlet for a pressurised fluid and the other chamber having an outlet for the fluid, a control port for providing communication between the chambers, being defined between co-operating parts of the housing and a piston which is slidably mounted in bores in the housing and extends through both of said chambers, the piston presenting an increased surface area to the fluid within said other chamber such that fluid entering said other chamber acts to urge the piston into a position to close the control port, spring means acting on the piston to oppose said fluid action to maintain the control port in an open condition consistent with the pressure required at the outlet of said other chamber, drain passages for leakage fluid extending from said bores to pressure control means for equalising the load due to the pressures oh opposite ends of the piston.

Preferably the pressure control means feeds the leakage fluid to the outlet of the said other chamber at the pressure existing in the outlet. In this way leakage of fluid between the piston and bores is accepted and used, the pressure control means equalising the force applied to opposite ends of the piston so that only the fluid pressure and spring force act upon the piston. Thus seals may be omitted from the piston reducing frictional forces.

In a preferred embodiment of the present invention wherein the piston has different diameter end regions located in complimentary bores, the leakage passages are connected with different axial regions of a venturi arranged at the outlet of the pressure regulator, the venturi forming said pressure control means. The relative axial positions of the leakage passage connections to the venturi are selected to balance the forces applied to the opposite ends of the piston, which can have different surface areas.

By virtue of this construction the provision of seals may be obviated and also, due to the leakage paths, the piston is held in the fully open, or substantially open, position when the tap or fluid cock at the regulator outlet is closed or only fractionally open, further opening of the outlet cock progressively closing the piston until an equilibrium position determining the maximum throughflow is achieved. Thus the regulator of the present invention can be used as a "water-saver" restricting the maximum throughflow irrespective of mains pressure, whilst allowing smaller quantities to flow therethrough.

The present invention will now be further described, by way of example, with reference to the accompanying drawing in which a crosssectional view of a preferred embodiment of the present invention is shown.

The pressure regulator illustrated in the accompanying drawing comprises a body 1 in which two chambers 3 and 5 are provided. One chamber 3 is connectible to a source of pressurised fluid via an inlet 7 and the other chamber 5 has an outlet 9. The chambers 3, 5 are interconnectible via a control port 11 which is defined between a port 13 of the housing and a piston 15; the piston having different diameter end regions 17, 19, slidably mounted in bores 21 and 23 respectively. The end regions 17, 19 of piston 1 5 are interconnected by a smooth and continuous waisted portion 25 upon which fluid pressure acts to move end region 17 to close the control port 11.Spring means 27 act against this movement and thus an equilibrium position is attained between fluid pressure on the waisted portion 25 and spring force, thereby providing for a substantially constant fluid pressure at the outlet 9. The actual outlet pressure is actively dictated by the load of spring means 27.

Bores 21 and 23 connect with leakage passages 29 and 31 respectively, these leakage passages being connected to different axial regions of a venturi 33 which forms a pressure control m-eans. Alternative suitable pressure control means can of course replace venturi 33.

The venturi 33 is connected to outlet 9 and has a narrow low pressure region 35 and two wider higher pressure regions 37 and 39, leakage passage 29 being connected to venturi higher pressure region 39 and leakage passage 31 being connected to venturi lower pressure region 35.

Positioning of the leakage passage connections to venturi 33, is selected to equalise the forces applied to opposite ends of the piston 1 5. Thus leakage past the piston can be overlooked and whilst low friction rings 41 are provided in the illustrated embodiment, these may be omitted without detriment and definitely with advantage due to the reduction in friction. More to the point, these leakage passages enable the regulator to pass fluid e.g. water, without the prior art disadvantage of possible external leakage and with adequate control of the flow rate at fractionally small and larger partial openings when a tap controlling the outlet is operated.

Thus, whilst restricting the maximum flow, the regulator of the present invention allows the controlled flow of smaller quantities of fluid to be obtained. This is particulariy advantageous in controlling a water supply the regulator then acting as a "water-saver". With prior regulators of the type disclosed in out copending British Patent Application No. 7923465 the tap would have inadequate control at partial openings with the possibility of external leakage past the pistons and via vents to the atmosphere, and thus such regulators would clearly not be suitable as "water-savers".

When working with high flow rates it is desirable for the venturi 33 to have tapered regions 41 and 43 to reduce turbulence and allow smooth flow. However, with certain lower flow rates, tapered region 41 can be omitted without much effect.

The present invention thus provides an efficient pressure regulator which can be used to limit the maximum fluid flow but which also allows lesser quantities to pass therethrough at a controlled flow rate determined by the selected opening of an outlet control cock.

Claims

1. A pressure regulator comprising a housing within which a pair of chambers are located, one of the chambers having an inlet for a pressurised fluid and the other chamber having an outlet for the fluid, a control port for providing communication between the chambers, being defined between co-operating parts of the housing and a piston, which piston extends through both of said chambers and is slidably received in bores in the housing, the piston presenting an increased surface area to the fluid within said other chamber such that fluid entering said other chamber acts to urge the piston into a position to close the control port, spring means acting on the piston to oppose said fluid action to maintain the control port in an open condition consistent with the pressure required at the outlet of said other chamber, drain passages for leakage fluid extending from said bores to pressure control means for equalising the loads due to the pressures on opposite ends of the piston.

2. A regulator as claimed in claim 1, in which the pressure control means feeds the leakage fluid to the outlet of said other chamber.

3. A regulator as claimed in claim 1 or claim 2, in which the pressure control means is in the form of a venturi, the leakage passages being connected to different axial regions of the venturi.

4. A regulator as claimed in claim 3, in which the venturi forms part of the outlet from said other chamber.

5. A regulator as claimed in claim 2, in which the pressure control means forms part of the outlet from said other chamber.

6. A regulator as claimed in any one of the preceding claims, in which seals are provided on each end of the piston within said bores.

7. A regulator as claimed in claim 6, in which the seals are made of a low friction material.

8. A pressure regulator constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.