DE2364269A1 - Safety diaphragm for pressurised fuel systems - dish shaped diaphragm welded into supply pipe bursts at overload pressure - Google Patents

Abstract

A built-in safety feature of a fuel supply system for liquid fuel missiles utilises a diaphragm that is designed to burst at a given over-load pressure. The dish shaped metal diaphragm is located in a branch section of the pressurised fuel supply canal. The diaphragm locates in a stepped section and seats securely against a shoulder. The interface between the diaphragm and the shoulder is election beam seam welded to provide a pressure tight seal.

Description

Arrangement of a bursting membrane in a pressure system, in particular a fuel delivery system of a liquid rocket engine

The invention relates to an arrangement of a curved bursting membrane in the flow channel of a pressure system, in particular the propellant delivery system of a liquid rocket engine, in such a way that the convex membrane face facing the pressure side and the membrane is aligned with that in the conveying direction

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pointing rear edge of its outer edge to a annular shoulder of the wall of the flow channel is supported, the inseparable, corrosion-resistant and pressure-tight executed connection of the outer edge of the membrane with the duct wall takes place in a defined manner, that at a certain response pressure and a small response pressure tolerance this connection breaks.

A bursting membrane is one that is intended to be installed in a flow path of a pressure system and is relatively understood thin membrane, which closes the flow path pressure-tight when installed, as long as the operating pressure is below a specified limit value, the so-called burst or response pressure, remain. As soon as the response pressure is reached, plus / minus a small response pressure tolerance, the Bursting membrane the entire cross-section of the relevant Free flow path by tearing at predetermined breaking points and as a whole from its holder solves. The membrane is deformed in such a way that it does not present any resistance to dispersion in the fuel system. It is held in a defined manner in a downstream safety gear.

This release of the flow path should therefore be more professional Installation provided - almost inertia-free and ~ practically without delay, i.e. with the smallest response tolerances take place. The frequent use of bursting membranes in many technical fields is on these last-mentioned, procedurally sometimes absolutely necessary or often desired Properties attributed »So they are among other things in systems working with increased operating pressure

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the chemical industry, refrigeration and nuclear reactor technology as devices to protect lines, equipment and machines against unexpected occurrences Excessive pressures used · They are also often found in liquid rocket engines Use, especially if this shelf life is required over a longer period of time. Through this there is no need for complex shut-off fittings. Here they should be in each one before the start-up of the engines Prevent harmful fuel leakage from the fuel tanks.

However, a bursting membrane can only take on the aforementioned protective and shut-off functions with certainty, if they are so and in such a way in the flow path to be shut off it is arranged that the following requirements are also satisfied at the same time over relatively long periods of time is done:

a) Absolute tightness during operation, even when storing corrosive media, as long as the response pressure is not reached,

b) high response accuracy due to extremely low burst pressure tolerance (less than 3% of the burst pressure),

c) short response time,

d) high load capacity and,

e) especially in liquid rocket construction, durability • against aggressive media.

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Those previously chosen for the known bursting membranes Arrangement types meet the aforementioned requirements

and
not fair enough in all points / precisely enough.

There are mainly two types of bursting membrane available on the market. Both types of membrane are curved formed, so each have a convex and a concave end face. The difference is there only in the different design of their edge areas and the resulting different Arrangement in the flow paths to be shut off. While In one type of membrane, the edge areas are profiled and bent up to form clamping beads, the additional Form sealing points, namely, such profiled clamping beads are missing in the other type of membrane.

Membranes of the first type are usually with their profiled clamping beads between two belonging to the flow path to be shut off, with one another clamped screwed connection flanges, namely such that their concave faces are on the pressure side..Die membranes of the latter type are according to another known type of arrangement first in each case in a radially inner 11 eg end annular groove of a circular " ring-shaped disc soldered in. Subsequently, the circular disks are placed in between of flat sealing rings between two belonging to the flow path to be shut off, with one another screwed connection flanges tensioned, in such a way that the convex end faces of the soldered to them Rupture membranes are on the pressure side.

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Both known bursting membrane arrangements are at risk of leaks Neither the profiled clamping beads of one of the bursting membranes nor those with the other beadless ones Sealing rings assigned to bursting membranes soldered to disks are capable of detachable flange connections to keep tight for a long time, especially at relatively high operating pressures and / or when the bursting membranes and the flanges that fix their position - as is the case, for example, with liquid rocket engines that have been in storage for a long time is the case - are exposed to frequent temperature fluctuations. With the latter. The bursting membrane arrangement has two further disadvantages. Once they hold the edge areas of the Rupture membranes with the circular disks pressure-tight connecting solder seams due to their geometric shape Reasons for relatively small seam depths and widths aggressive media, of which a large number of the common rocket fuel counts, it was difficult to stand for a long time. On the other hand, there remains a soldering, even if no aggressive media occur, only with relatively thick bursting membranes that are related to Response accuracy and response time are inferior to comparatively thin bursting membranes without damaging them Follow. The thin and therefore special ones guarantee the high response accuracy and the shortest response times deformation-prone bursting membranes would namely due to the locally different heating and cooling of large areas of the rupture membrane, which cannot be avoided during the soldering process Deformations that undesirably change the response pressures and sometimes lead to premature destruction suffer.

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Furthermore, according to US Pat. No. 3,667,644, an arrangement of a curved bursting membrane in the flow channel of a pressure system is known, according to which the convex The face of the membrane faces the pressure side and • the membrane is facing in the conveying direction rear edge. its outer edge is supported on an annular shoulder of the wall of the flow channel, whereby the non-detachable and pressure-tight connection of the outer edge of the membrane with the duct wall defined in such a way that with a certain

Response pressure this connection breaks.

This version also does not yet meet the high requirements for response accuracy in Form of extremely low burst pressure tolerances, as the tearing of the membrane practically only occurs from the given specific tensile strength of the manufactured. Connection is dependent, the exact value of which is simply not calculable during production.

The invention is therefore based on the object to provide such a connection that with security a extremely high response accuracy. even when using corrosive media with simple production of such media Connection guaranteed.

Zur.Lösung this object is proposed according to the invention, to connect the bursting membrane to the duct wall only with its rear edge of its outer edge.

In an embodiment of the invention, the rear edge of the bursting membrane is connected to the channel wall by electron beam welding. Be that way

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Tensions, structural changes that endanger the sensitive bursting membrane or severely impair its mode of operation and the resulting distortions are safely avoided or to a negligible level Reduced size, because in electron beam welding the sharply delimited penetrates with means The electron beam can be precisely adjusted to the joint between the bursting membrane and the mounting ring using the electron optics and with this the required heat only in a very narrow zone on both sides of the joint located material.

The inventive arrangement of the connection between the edge of the bursting membrane at its rear edge and the flow channel therefore guarantee a maximum Response accuracy and the lowest bursting pressure tolerance, because here the connection seam is practically from the beginning of the Bursting load is subjected to an unhindered combined torsional and bending stress, wherein here mechanically the load force in the center of the Leverage has a maximum. This also requires the shortest possible response times.

the drawing shows an exemplary embodiment of a bursting membrane arranged according to the invention in a flow channel in section. - ',' ..

A curved bursting membrane is installed in a flow channel 1 with its convex side pointing towards the pressure chamber 3. The outer edge 4 is seated appropriately in an annular surface 5 of a collar 6 of the flow channel 1. The bursting membrane 2 is only facing away from the pressure chamber 3 with its one rear edge 7 of their outer edge 4 with the collar 6 of the Cooling channel 1 connected in a pressure-tight manner, namely with a Weld seam 8, which is produced in particular by electron beam welding.

- 8 50 9828 / 002.8

In the drawing, for better illustration of the situation, the weld seam 8 is only on the right Half of the picture shown.

Patent claims:

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Claims (2)

Messerschmitt-Bölkow-Blohm Ottobrunn, December 19, 1973 Company with BS63 Hn / er limited liability Munich 7652 Claims Ii) Arrangement of a curved bursting membrane in the flow channel a pressure system, in particular a fuel delivery system for a liquid rocket engine, in such a way that the convex membrane face faces the pressure side and the Membrane with the rear edge of its outer edge pointing in the conveying direction onto an annular one Paragraph of the wall of the flow channel is supported, the inseparable, pressure-tight and corrosion-resistant executed connection of the outer edge of the membrane with the duct wall takes place in a defined manner, that this connection breaks at a certain response pressure, characterized in that the bursting membrane (2) only is connected with its rear edge (7) to the duct wall (1). 2. Arrangement according to claim 1, characterized in that the connection of the rear The edge (7) of the bursting membrane (2) with the duct wall (1) is carried out by means of an electron beam weld (8). 509828/0028 • 40 .. Blank page