GB2141181A

GB2141181A - Hydraulic pressure supply device

Info

Publication number: GB2141181A
Application number: GB08315686A
Authority: GB
Inventors: Raymond Clough; Stuart David Hammond; Brian Edwin Letton Travers
Original assignee: UK Secretary of State for Defence
Current assignee: UK Secretary of State for Defence
Priority date: 1983-06-08
Filing date: 1983-06-08
Publication date: 1984-12-12
Also published as: GB8315686D0

Abstract

An hydraulic pressure supply device in which the motive pressure is derived from a charge (6) burning in the manner of a cigarette, the pressure generating chamber (1a) of the accumulator having a pressure relief valve (3) whereby substantially constant hydraulic pressure can be maintained. When used in a missile or unmanned aircraft an initiator is fired to commence the burning of the charge. Operation of a device to be supplied by the accumulator results in a burster disc 8 rupturing. <IMAGE>

Description

SPECIFICATION Improvements in accumulators The present invention relates to accumulators of the type which are capable of supplying a pressurized fluid for motive purposes of limited duration. It is particularly concerned with an hydraulic accumulator for supplying power for the operation of controls and control surfaces in missiles and unmanned aircraft.

In a known hydraulic accumulator a diaphragm divides a pressure vessel into two chambers, the one a pressure generating chamber containing a gas at pressure, perhaps in liquid form, and the other a working fluid reservoir having an outlet for connection to an hydraulic circuit. In such accumulators constant operating pressure is difficult to maintain. Moreover, in the light of the present invention, such accumulators are not particularly efficient in terms of bulk per unit power output.

The invention provides an hydraulic accumulator in which the available power is maximised per unit bulk and which is capable of supplying hydraulic fluid throughout a charge duration at substantially constant pressure.

Moreover the accumulator may readily be made reusable, possibly even reversable.

An accumulator according to the present invention comprises a pressure vessel, a diaphragm within the vessel whereby a working fluid reservoir and a pressure generator chamber are defined one on each side of the diaghragm within the vessel, a fluid outlet from the working fluid reservoir, and a control valve associated with the pressure generation chamber, the pressure generator chamber being arranged to accommodate a gas generating charge.

According to a feature of the invention the pressure generating chamber may include a gas generating combustible charge arranged to have a substantially constant burning surface area, and a high aspect ratio. Thus the charge may be almost a toroid, perhaps of circular cross section although if it is formed by cutting from a tube of propellant the section may be rectangular.

The control valve may be a relief valve exhausting excess gas in the pressure generator chamber to the exterior. Preferably the fluid outlet is sealed, until use is commenced, by a burster disc or a remotely controlled valve, or both. The working fluid may be a gas but is preferably an hydraulic liquid.

According to another feature of the invention the diaphragm may be arranged to be so flexible as to be capable, commencing from an attenuated pressure generator chamber volume, of attenuating the fluid reservoir volume.

In a preferred embodiment of the invention the vessel is substantially spherical with a right cylindrical portion while the diaghragm, which is formed of a metal, comprises a cylindrical bellows portion fitting within the vessel cylindrical portion, an invertable part spherical portion extending across the vessel, and an annular hollow for receiving a solid charge in toroidal form. The part spherical portion may include bellows rings to assist in inversion. In this way the working fluid reservoir can be arranged to constitute almost the whole of the vessel volume, with the pressure generating chamber scarcely larger than is necessary to accommodate the charge and to allow the diaphragm its required room for configuration change. The wall of the pressure vessel bounding the pressure generator chamber may be lined with a thermal insulant.

An hydraulic accumulator in accordance with the present invention will now be described by way of example with reference to the accompanying drawing, which is a part longitudinal section of the accumulator.

As shown in the drawing the accumulator comprises a pressure vessel 1 devided into two chambers by a metal diaphragm 2, one chamber constituting a pressure generator chamber and having a relief valve 3 therefrom, and the other constituting an hydraulic liquid reservoir and having an exit orifice 4 therefrom.

The pressure vessel 1 is in two parts, a generator chamber part 1 a having a cylindrical side wall and a spherical end wall, and a reservoir part 1 b of part spherical form. The two parts are adapted to be screwed together.

The generator part 1 a has a thermal insulant lining 5.

The diaphragm 2 comprises a cylindrical bellows portion 2a and a spherical head 2b, with an annular charge accommodating recess 2c therebetween. The head 2b incorporates annular convolutions 2d to assist in permitting inversion thereof. The diaphragm has a rim 2e in lip form whereby it can be welded to the part 1 b. The diaphragm 2 is formed of stainless steel.

A solid charge 6 is accommodated between the diaphragm recess 2c and the spherical end wall of the vessel generator chamber part 1a. It is a platonised charge in the form of an open toroid arranged to burn in the manner of a cigarette. There is an initiator, not shown, having an associated connector 7 passing through the part 1 a via a glass to metal seal 7a.

The accumulator is assembled by connecting the charge 6 and initiator within the vessel part 1 a, bonding the charge 6 into the diaphragm recess 2c, entering the diaphragm 2 on the part 1 b into the vessel part 1 a, and screwing the vessel part 1 b home into the vessel part la. The reservoir, if not already filled, is then filled with hydraulic liquid via the orifice 4 and the latter sealed with a burster disc 8.

When required for use in say an unmanned vehicle the accumulator can be attached into the vehicle's hydraulic circuit. Upon take-off the initiator is fired to commence the burning of the charge, when the gaseous products of combustion pressurise the pressure chamber.

The pressure relief valve then operates to ensure a constant pressure in that chamber.

When any device in the hydraulic circuit is operated the burster disc 8 ruptures and the pressurized hydraulic liquid becomes available to power the operation. The bellows 2 collapses into the reservoir chamber as hydraulic liquid leaves it, until eventually the bellows 2a are tightly closed and the head 2b inverts, substantially attenuating the volume of the reservoir chamber.

Claims

1. An accumulator comprising: a pressure vessel, a diaphragm within the vessel whereby a working fluid reservoir and a pressure generator chamber are defined one on each side of the diaphragm within the vessel, a fluid outlet from the working fluid reservoir, and a control valve associated with the pressure generator chamber, the pressure generator chamber being arranged to accommodate a gas generating combustible charge.

2. An accumulator as claimed in claim 1 and wherein the pressure generating chamber contains a gas generating combustible charge arranged to have a substantially constant burning surface area, and a high aspect ratio.

3. An accumulator as claimed in claim 2 and wherein the charge is a substantially toroidal.

4. An accumulator as claimed in claim 3 and wherein the charge is formed by cutting from a cylinder of propellant.

5. An accumulator as claimed in any one of claims 1 to 4 and wherein the control valve is a pressure relief valve.

6. An accumulator as claimed in any one of the preceding claims and wherein the fluid outlet is sealed, until use is commenced, by a burster disc.

7. An accumulator as claimed in any one of the preceding claims, and wherein the working fluid is an hydraulic liquid.

8. An accumulator as claimed in any one of the preceding claims and wherein the diaphragm is arranged to be so flexible as to be capable, commencing from an attenuated pressure generator chamber volume of attenuating the fluid reservoir volume.

9. An accumulator as claimed in any one of the preceding claims and wherein the diaphragm comprises a cylindrical bellows portion and an invertable domed portion.

10. An accumulator as claimed in claim 9 and wherein the domed portion of the diaphragm has convolutions for assisting inversion.

11. A guided missile having an hydraulic accumulator as claimed in any one of the preceding claims.

1 2. An hydraulic accumulator substantially as hereinbefore described with reference to the accompanying drawing.