EP0790906A1

EP0790906A1 - Liquid gas generator

Info

Publication number: EP0790906A1
Application number: EP95940169A
Authority: EP
Inventors: Heinz Riess; Uwe Brede; Wolfram Seebeck
Original assignee: Dynamit Nobel AG; Dynamit Nobel GmbH Explosivstoff und Systemtechnik
Current assignee: Dynamit Nobel AG; Dynamit Nobel GmbH Explosivstoff und Systemtechnik
Priority date: 1994-11-11
Filing date: 1995-11-09
Publication date: 1997-08-27
Also published as: CZ143097A3; MX9703452A; BR9509643A; KR970706991A; CN1171759A; PL320136A1; CA2204787A1; TW286302B; WO1996015012A1; DE4440247A1; TR199501388A2

Abstract

A liquid gas generator for inflatable air bags that protect vehicle passengers in the event of a collision has a housing, a closed liquid gas reaction container (7) arranged in the housing, a cavity (9) arranged in the housing next to the reaction container (7), a firing element (4), and a piercing element (16) movable in the cavity that pierces a wall of the reaction container (7) when the firing element (4) is actuated, allowing the liquid gas combustion gases to escape from the reaction container (7) into the cavity (9) and from there out of the housing into the air-bag. In order to make it easier to open and pierce the reaction container (7) and to generate gas in a controlled and reproducible manner during the whole service life of the liquid gas generator, the piercing element (16) pierces with its whole length the wall of the reaction container (7) and penetrates in its entirety into the reaction container (7).

Description

LPG generator

The invention relates to a liquid gas generator according to the preamble of claim 1.

In passive safety devices for motor vehicles, in which drivers or passengers are protected from injuries by impacts on the steering wheel or dashboard (also called air bags) by inflatable impact protection cushions, either gas generators with a fixed propellant charge set or gas generators with compressed pressurized are used for gas generation Gas (hybrid generator, compressed air generator) or also generators with liquid gas mixtures, some of which actively participate in combustion, are used. The advantages of gas mixtures over fixed propellant charges when used in a generator are well known. A problem with gas or liquid gas generators is that the pressurized gases have to be enclosed in a container which, in the application, i.e. must be opened when the generator is triggered.

DE 42 41 221 A1 discloses a liquid gas generator for an inflatable impact protection cushion for protecting a motor vehicle occupant from injuries. The liquid gas generator has a housing in which a reaction container with liquid gas is accommodated. To trigger combustion of the liquid gas, a breakdown element with an overflow channel is driven therein. The kinetic energy for the breakdown element is generated pyrotechnically by initiating an ignition element. The ignition fumes from the ignition element reach the inside of the reaction vessel via the overflow channel, where they initiate the combustion of the liquid gas. The resulting combustion gases pass through the overflow channel out of the reaction container into a cavity in which the breakdown element is arranged. The cavity is closed by a bursting membrane against an outflow space (through hole). This bursting membrane breaks open when a minimum pressure of the combustion gases is reached and thus clears the way for the combustion gases to be removed via the outflow space (through hole) out of the housing.

ORIGINAL DOCUMENTS The disadvantage of this is that the striking element or the striking piece must lie directly on the reaction container, since otherwise pressure can build up behind the striking piece, which prevents the reaction container from striking through. There is also a risk that the striking piece is loaded asymmetrically, which in turn can lead to uncertainties when striking through. Another essential disadvantage is the necessary bursting membrane, through which the cavity is designed as a pressure chamber. Firstly, these bursting membranes are extremely expensive and secondly, if only one bursting membrane is used, a recoil is generated by the escaping gas, which causes an undesirable torque of the gas generator.

The invention has for its object to improve a liquid gas generator according to the preamble of claim 1 such that the opening or breaking through of the reaction vessel is simplified and that the gas generation is controlled and reproducible over the total operating time.

To achieve this object, a liquid gas generator is proposed according to the invention, the housing of which contains a closed reaction container for receiving liquid gas. A cavity is formed in the housing, which adjoins this when the reaction container is inserted. A breakdown element is displaceably arranged in the cavity and, when an ignition element is ignited, its entire length is driven through the wall of the reaction container and fully immersed in the reaction container. After puncturing or punching the wall of the reaction container through the penetration element and further penetration of the penetration element into the previously closed reaction container, there is thus a connection with the diameter of the penetration element.

A major advantage is the lack of a separate pressure chamber with a rupture disc. This gives a decisive price advantage. Due to the lack of a rupture disc, a symmetrical outflow can easily be achieved through a larger number of outflow bores across the diameter. A recoil or an undesired torque is avoided. Another advantage is the simple construction of the gas generator, which can only be produced from rotationally symmetrical components.

The punch element is advantageously a solid body. In a preferred embodiment according to the invention, for better penetration / punching through the wall of the reaction container, the penetration element is designed as a projectile, that is to say a cylinder with a cone, ball, cylinder etc. attached to it.

In an advantageous embodiment, the ignition element contains a squib.

The ignition element or squib is ignited to trigger the LPG generator. The combustion gases that are generated when the ignition element is ignited drive the breakdown element through the wall of the reaction container. The ignition element and the breakdown element are connected to one another in such a way that a clean punching through of the partition is guaranteed in any case. The penetration of the subsequent hot gases into the reaction container and the outflow of the liquid gas mixture into the cavity cause the liquid gas mixture to ignite and react. The resulting combustion gases are discharged through overflow channels emanating from the cavity. The shape, position and diameter of the overflow channels allow the gas generation to be controlled and reproducible. As a result, the use of complex rupture disks in this area can be omitted. The combustion gases entering the overflow channels pass out of the gas generator via outflow bores in the housing, where they inflate the folded impact protection cushion.

As already mentioned, the penetration element is advantageously designed in the form of a projectile in order to ensure safe and defined penetration of the partition. The breakdown element is advantageously connected to the ignition element or a sleeve via a tear-off edge, so that the breakdown element can only move with high energy after a defined pressure has arisen, caused by the combustion gases of the ignition element.

Alternatively, a radial extension and / or a radial constriction is arranged on the penetration element. In order to achieve the energy required to break through the wall, a cavity (utilizing the combustion gases) is advantageously arranged between the breakdown element and the ignition element. The cavity is advantageously filled with a charge. The charge is advantageously a pyrotechnic propellant powder or ignition mixture such as nitrocellulose, a boron potassium nitrate mixture or a black powder mixture. According to the invention, the ignition element is advantageously provided with a cylindrical guide sleeve for guiding the breakdown element.

The breakdown element advantageously consists of a temperature-stable, combustible molded part which, after penetrating into the reaction vessel, is also burned by the high temperature which arises during the conversion of the gas. Another advantage is that when the breakdown element flows back through the opening, it can no longer clog an overflow channel when it burns. The punch element, the tear-off edge and the sleeve are preferably a molded part.

The wall of the reaction container to be penetrated by the penetration element is expediently a rupture disk which is preferably integrated in the lid of a closure cap of the reaction container.

Further features result from the figures, which are described below. It shows:

1 shows a liquid gas generator according to the invention in section,

Fig. 2 shows a first embodiment of an ignition element in partial section and

Fig. 3 shows a second embodiment of an ignition element in section.

1 shows a liquid gas generator 1 according to the invention, which essentially consists of a head piece 2, a base piece or adapter 9 and a cylindrical outflow pipe 10. Outflow bores 11 are arranged in the outflow pipe 10. In addition, a reaction container 7 is arranged in the outflow pipe 10 or in the liquid gas generator 1 as an intrinsically pressure-resistant bottle. In this reaction container 7 there is liquid gas or a liquid ^; gas mixture. The reaction container 9 serves as a storage container and as a combustion chamber of the liquid gas mixture. The end of the reaction container 9 is closed by a rupture disk 5. The rupture disc 5 is integrated in the lid of a closure cap 18. This closure cap 18 is screwed into the head piece 2 via a thread 20 such that a cavity 9 is adjacent to the rupture disk 5. Overflow channels 6 lead from the cavity 9 into the intermediate space between the reaction container 7 and the discharge pipe 10. In the head piece 2 there is also an ignition element holder 3 with an ignition element 4. The front tip of the ignition element 4 has a penetration element 16 designed as a projectile and projects with it into the cavity 9. The ignition element 4 lies on the longitudinal axis 21 of the reaction container 7.

The reaction container 7 is advantageously made of tempered steel. The housing is also advantageously made of steel or aluminum.

3 shows a variant of the ignition element 4. The ignition element 4 is inserted into the ignition element holder 3. The ignition element 4 consists of a squib 12 and a cavity between the striking element 16 and squib 12 which is filled with a charge 13. The punch element 16 is firmly connected to the ignition element 4 by shaping via a sleeve 14 with a tear-off edge 15. In the event of ignition, the ignition element 4 is ignited, the gases and hot particles that are ignited ignite the charge 13. Since the penetration element 16, which is firmly connected to the ignition element holder 3 via the sleeve 14 and tear-off edge 15, cannot start to move, pressure build-up is determined by the thickness of the tear-off edge 15. After a certain defined pressure has been reached, the breakdown element 16 and the sleeve 14 tear off very quickly at the tear-off edge 15. The guide sleeve 17 of the ignition element holder 3 leads to a directional acceleration of the breakdown element 16. The breakdown element is in the Guide sleeve 17 accelerated defined by the combustion gas pressure (principle of a projectile in a short barrel).

After the breakdown element 16 has been separated from the ignition element 3 or ignition element 4, the breakdown element 16 crosses the cavity 7 of the head piece 2 and penetrates the rupture disk 5, which separates the liquid gas mixture in the combustion chamber 8 from the head piece 2 or cavity 9 separates (see Fig. 1). The LPG mixture in the combustion chamber 8 is ignited by the hot gases and hot particles of the ignition element 4 following the breakdown element 16. Via the opening of the rupture disc 5, there is a volume expansion into the cavity 9 of the head piece 2 and thus begins through the overflow channels 6 and the outflow holes 11, the inflation of the gas bag. Gas flow and pressure increase in the cavity 9 of the head piece 2 can be controlled by position, diameter and the number of overflow channels 6 defined. The penetration element 16 can consist of a temperature-stable, combustible molded part (plastic or metal) which is designed as a projectile. Due to the high temperature that arises during the conversion of the liquid gas mixture, the penetration element 16 burns after penetration into the combustion chamber 8.

FIG. 2 shows a slightly different embodiment of the breakdown element 16 and the charge 13 compared to FIG. 3. The breakdown element 16 is here not connected to the sleeve 14 or the ignition element 4 via a tear-off edge 15. For this purpose, a radial extension 31 is arranged on the penetration element 16. Alternatively, a radial constriction 30 can also be provided in the guide sleeve. Both measures, like the tear-off edge 15 in FIG. 3, cause a directed acceleration of the penetration element 16 only after a certain pressure has been reached.

Claims

claims

1.) LPG generator for an inflatable impact protection cushion to protect a motor vehicle occupant from injury, with

a housing, a closed arranged in the housing

Reaction container (7) for holding liquid gas, - a cavity (9) adjacent to the reaction container (7) in the

Housing, an ignition element (4), and a breakdown element movable in the cavity (9)

(16) for penetrating a wall of the reaction container (7) upon initiation of the ignition element (4), the combustion gases of the liquid gas from the reaction container (7) into the cavity

(9) and from there out of the housing to

Impact protection cushion

characterized in that the entire length of the penetration element (16) penetrates one wall of the reaction container (7) and fully immerses it in the reaction container (7).

2.) LPG generator according to claim 1, characterized in that the breakthrough element (16) is a solid body.

3.) LPG generator according to claim 1 or 2, characterized in that the penetration element (16) is designed as a projectile.

4.) LPG generator according to one of claims 1 to 3, characterized in that the penetration element (16) via a tear-off edge (15) with the ignition element (4) or a sleeve (14) is connected.

5.) LPG generator according to one of claims 1 to 4, characterized in that the penetration element (16) consists of a temperature-stable combustible molded part.

6.) LPG generator according to claim 4 or 5, characterized in that the penetration element (16), the tear-off edge (15) and the sleeve (14) are a molded part.

7.) LPG generator according to one of claims 1 to 6, characterized in that the ignition element (4) is provided with a cylindrical guide sleeve (17) for guiding the breakdown element (16).

8.) LPG generator according to one of claims 1 to 7, characterized in that a radial enlargement (31) and / or in the guide sleeve (17) a radial constriction (30) is arranged on the penetration element (16).

9.) LPG generator according to one of claims 1 to 8, characterized in that the ignition element (4) contains a squib (12).

10.) LPG generator according to one of claims 1 to 9, characterized in that a cavity is arranged between the ignition element (4) and the breakdown element (16), which is preferably filled with a charge (13).

11.) LPG generator according to one of claims 1 to 10, characterized in that the one wall of the reaction container (7) is a rupture disc (5).

12.) LPG generator according to claim 11, characterized in that the rupture disc (5) in the lid of a closure cap (18) of the reaction container (7) is integrated.