GB2490771A

GB2490771A - Gas spring accumulator with port for communication with external pressure vessel and an indicator member

Info

Publication number: GB2490771A
Application number: GB1207554.5A
Authority: GB
Inventors: Frederick Philip Selwyn
Original assignee: WATER POWERED TECHNOLOGIES Ltd
Current assignee: WATER POWERED TECHNOLOGIES Ltd
Priority date: 2011-04-26
Filing date: 2012-05-01
Publication date: 2012-11-14
Anticipated expiration: 2032-05-01
Also published as: GB2490771B; GB201207554D0

Abstract

A gas spring accumulator includes a housing 2, 3 provided with an inlet 20 and a flexible diaphragm 4 dividing the interior of the housing into a working chamber 7 which is exposed to system pressure via the inlet 20 and a gas chamber 6. A port 23 is provided for attachment of an external pressure vessel in the form of a length of pressure hose 24 and an indicator rod 31 visible through a sight capsule 33 shows when the gas charge balances the system pressure. The housing may also comprise an outlet 21.

Description

GAS SPRING ACCUMULATOR

TECHNICAL FIELD OF THE INVENTION

This invention relates to accumulators of the kind which incorporate gas springs.

BACKGROUND

Accumulators may be used to store a volume of fluid under pressure or absorb pressure shocks caused by a sudden pulse of fluid entering an hydraulic system. Such accumulators may contain a sealed moveable member such as a flexible diaphragm or piston with a compressible gas or mechanical spring on one side acting in opposition to the system fluid pressure on the other. Whilst the characteristics of a mechanical spring must be pre-selected at the outset to be compatible with the range of pressures likely to be encountered in the system, a gas spring has the advantage that its characteristics can be changed at any time by charging or releasing the gas pressure, as required.

One disadvantage of gas spring accumulators is that a large gas chamber may be required to store the charge. Such devices are often difficult to accommodate, and may also be subject to vigorous pressure testing requirements. Furthermore, there is usually no easy way of determining when the accumulator is charged to a pressure which is compatible with the system pressure, which may necessitate taking readings of the system pressure and the gas charge.

The present invention seeks to provide a new and inventive form of accumulator which is relatively compact and lightweight yet is capable of accommodating a large pressure charge when required. A second aim is to provide an indication of the charge pressure without using additional pressure gauges.

SUMMARY OF THE INVENTION

The present invention proposes a gas spring accumulator comprising: -a housing provided with an inlet; and -a flexible diaphragm dividing the interior of the housing into a working chamber which is exposed to system pressure via the inlet, and a gas chamber; in which the housing is provided with a port which communicates with the gas chamber and which is adapted for attachment of an external pressure vessel.

A preferred form of pressure vessel comprises a length of flexible conduit.

The invention also provides a gas spring accumulator comprising: -a housing provided with an inlet; -a flexible diaphragm dividing the interior of the housing into a working chamber which is exposed to system pressure via the inlet, and a gas chamber, the diaphragm carrying a diaphragm support assembly; and -an indicator member, movable by the diaphragm support assembly, projects through the wall of the housing.

The indicator member preferably projects into a sight element which is mounted on the outside of the chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice.

In the drawings: Figure 1 is a sectional view of a pneumatic accumulator in accordance with the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring firstly to Fig. 1, the accumulator comprises a housing 1 formed with upper and lower parts 2 and 3, which may be cast of metal or moulded of plastic for example. A flexible diaphragm 4 is interposed between the housing parts 2 and 3, with a peripheral bead 5 sealably interposed between the two parts.

The diaphragm thus divides the interior of the housing into an upper gas chamber 6 and a lower working chamber 7. A central region of the diaphragm 4 is held by a support assembly 8, including upper and lower disc-shaped support elements 9 and 10, and the diaphragm is sealably sandwiched between the two elements, which are clamped together by a nut-and-bolt fixing 11 passing through the diaphragm. The disc-shaped elements 9 and 10 are both provided with shallow peripheral flanges 12.

The support assembly 8 is supported in a rest position by a compression spring 14, located within the working chamber 7.

The spring is radially located within a recess 15 at the bottom of chamber 7, and by the peripheral flange 12 of the lower support element 10.

The two housing parts 2 and 3 can be held together by bolts 16.

The lower housing part 3 is provided with axially aligned fluid inlet and outlet ports 20 and 21, one or both of which can be used to connect the working chamber 7 to the system fluid pressure. The accumulator may typically be connected in a liquid flow line, for example. The upper part 2 is provided with a gas port 23 for connection to an expansion vessel in the form of a conduit such as a length of pressure hose 24. The hose is sealed at the far end by a suitable end fitting 25 to provide a sealed pneumatic chamber which may be charged with gas via a suitable charge valve 26 on the upper housing part 2. The pressure hose can easily be accommodated in any convenient space. Furthermore, by selecting a standard pressure hose and fittings with an appropriate pressure rating the need for pressure testing of the expansion vessel is avoided. The capacity of the expansion vessel can easily be adjusted to the size required for any particular application simply by changing the length and/or diameter of the hose.

The accumulator also incorporates a charge indicator comprising an indicator element provided by a rod 31 which is slidably inserted through a port 32 on the upper housing part 2. The lower end of the rod 31 is in contact with the upper support element 9, located within the flange 12. The rod 31 projects into a transparent sight capsule 33 which is sealably engaged with the port 32. When the working chamber 7 is subjected to system pressure exceeding the pressure exerted by the charge within the gas chamber 6 and pressure hose 24, the diaphragm 4 will tend to move upwards, causing the indicator rod to rise within the sight capsuie 33. Thus, movement of the indicator rod 31 will indicate that compression of the gas charge is occurring and the system fluid is expanding into the chamber 7.

As the system pressure falls the diaphragm returns under the influence of the compressed gas charge, expelling a proportionate quantity of system fluid from the chamber 7.

The accumulator can also be used with negative pressures so that if a partial vacuum is introduced into the gas chamber 6 and a negative pressure is applied to the fluid in the working chamber 7 the diaphragm will move downwards against the action of spring 14 but will return as the pressure of the working fluid increases.

The accumulator is suitable for use in a variety of applications, including pressure accumulation, shock suppression and fluid pumping. The accumulator can, for example, be used to prevent water hammer in water pumping systems due to fluctuating flows and pressures. The accumulator could also be as a means of pumping fluid, whereby system fluid can be induced and expelled by the application of variable pressure on the opposite side of the accumulator diaphragm using appropriate non-return valves on the inlet and/or outlet ports to create a unidirectional flow through the working chamber.

Although a pneumatic accumulator is described, using air as the gas charge, it will be appreciated that other compressible gases could be used, e.g. nitrogen.

Whilst the above description places emphasis on the areas which are believed to be new and addresses specific problems which have been identified, it is intended that the features disclosed herein may be used in any combination which is capable of providing a new and useful advance in the art.

Claims

CLAIMS1. A gas spring accumulator comprising: -a housing provided with an inlet; and -a flexible diaphragm dividing the interior of the housing into a working chamber which is exposed to system pressure via the inlet, and a gas chamber; in which the housing is provided with a port which communicates with the gas chamber and which is adapted for attachment of an external pressure vessel.
2. A gas spring accumulator according to Claim 1 in combination with a external pressure vessel for external attachment to the port which communicates with the gas chamber.
3. A gas spring accumulator according to Claim 2 in which the pressure vessel comprises a length of conduit.
4. A gas spring accumulator according to Claim 3 in which the length of conduit is flexible.
5. A gas spring accumulator according to any preceding claim in which the working chamber is provided with a fluid outlet such that the fluid inlet and outlet can be used to connect the
6. A gas spring accumulator according to any preceding claim in which the diaphragm carries a diaphragm support assembly.
7. A gas spring accumulator according to Claim 6 in which the diaphragm support assembly comprises a pair of support elements located on opposite sides of the diaphragm.
8. A gas spring accumulator according to Claim 7 in which the diaphragm is sealably sandwiched between the support elements which are held together by a fixing element passing through the diaphragm.
9. A gas spring accumulator according to Claim 6, 7 or 8 in which the working chamber contains a spring which acts against the diaphragm support assembly.
10. A gas spring accumulator according to any of Claims 6 to 9 in which an indicator member, movable by the diaphragm support assembly, projects through the wall of the housing.
11. A gas spring accumulator according to Claim 10 in which the indicator member projects into a sight element which is mounted on the outside of the chamber.
12. A gas spring accumulator comprising: -a housing provided with an inlet; -a flexible diaphragm dividing the interior of the housing into a working chamber which is exposed to system pressure via the inlet, and a gas chamber, the diaphragm carrying a diaphragm support assembly; and -an indicator member, movable by the diaphragm support assembly, projects through the wall of the housing.
13. A gas spring accumulator according to Claim 12 in which the indicator member projects into a sight element which is mounted on the outside of the chamber.
14. A gas spring accumulator according to Claim 12 or 13 in which the diaphragm support assembly comprises a pair of support elements located on opposite sides of the diaphragm.
15. A gas spring accumulator according to Claim 14 in which the diaphragm is sealably sandwiched between the support elements which are held together by a fixing element passing through the diaphragm.
16. A gas spring accumulator according to any of Claims 12 to in which the working chamber contains a spring which acts against the diaphragm support assembly.
17. A gas spring accumulator substantially as described with reference to the drawings.