CZ305260B6 - Plastic gas generator and process for producing thereof - Google Patents

Abstract

In the present invention, there is disclosed a plastic gas generator having a holder (1) that carries contacts (2) and a pyrotechnic mixture (3). The holder (1) is arranged within a plastic casing (4), the material of which comprises detection and/or tracing elements or component, whereby the base (4a) and the bottom (4b) of the casing (4) are encompassed from outside by a reinforcing liner (5). The casing (4) body (4c) is provided in its upper portion with a plug (6), being tightly coupled all over its circumference with the casing (4) body (4c) forming therewith an integral enclosed space of a chamber (7). A process for producing the above-indicated plastic gas generator according to the present invention comprises is characterized in that the holder (1) with contacts (2) and the pyrotechnic mixture (3) is provided with a reinforcing liner (5) and this assembly is then put into an injection mold being preheated to a temperature ranging from 50 to 150 degC, where a plastic casing (4) is injected from a melt at a temperature ranging from 150 to 350 degC. After subsequent cooling down of the plastic casing (4) and pouring a propellant therein a plug (6) is placed thereabove and tightly sealed with the casing (4) by a laser, ultrasonic or rotary welding process, optionally by a metal strip. The plastic gas generator according to the present invention can be used for passive safety elements in automobile industry and further in all systems requiring quick generation of gaseous products serving as an energy source.

Description

Plastic pin gas generator and method of its production

Technical field

The present invention relates to a gas generator for use in seat belt pretensioners as part of a passive protection of occupants of a vehicle. This system is particularly useful in the automotive industry. The invention further relates to a method for manufacturing this plastic pin gas generator.

BACKGROUND OF THE INVENTION

As is known to date, micro gas generators (MGGs) are used as gas generators for seat belt pretensioners in the automotive industry.

These gas generators can be roughly divided into a group of pin and leadwire MGG.

The prior art known MGG pin design is based on the use of metal, especially aluminum components. These MMGs consist of a holder-holder as a carrier component of the initiator, the initiator itself, the shorting element, the metal container-cup-wrapper with a defined amount of propellant, an explosive used to generate gases. All of these components come as individual components which, once assembled together, form a single compact unit of the MGG for use in seat belt pretensioners.

The construction of the lead (leadwire) MGG is very similar to the first type mentioned. Compared to pin MGG, however, mainly plastic materials are used to design cable MGG. MGG wire ropes consist of a plastic subassembly in which the initiator is sprayed. For example, an electric conductor is welded on this initiator by resistance welding. This subassembly (as one of the components) is assembled with a plastic or metal cup containing propellant.

The operating principle of MGG is such that when an electric pulse is applied to an initiator (usually called a squib, a pill, etc.), it is initiated which further causes the propellant propellant to burn. This leads to the generation of gases. The developed gas is then a source of energy for the moving parts used in the seat belt pretensioner.

The disadvantages of these described MGGs are their relatively high cost and limited variability of the initiator, holder and propellant container combinations. Other disadvantages are the limited tightness of MGG and the complicated way of assembling components where mechanical presses are needed to assemble them in modules or other devices.

SUMMARY OF THE INVENTION

The above-mentioned disadvantages and drawbacks of the known conventional types of gas generators are largely eliminated by the plastic pin gas generator according to the invention. SUMMARY OF THE INVENTION The invention is characterized in that the holder carrying the contacts and the pyrotechnic composition is housed in a plastic housing, the material of which comprises detection and / or marking elements or a component, the housing base and bottom being surrounded by a reinforcement insert from the outside; provided with a cap which is tightly connected to the housing body on its circumference with which it forms an integral enclosed chamber space.

The principle of the production method of the plastic pin gas generator according to the invention is further characterized in that the contact holder and the pyrotechnic assembly are provided with a strengthening insert and this assembly is

The plastic sleeve is injected into the preheated injection mold, where the plastic sleeve is injected from the melt, after cooling the plastic sleeve and the propellant sleep, a cap is placed from above, which is tightly connected to the sleeve by laser or heat welding or metal tape.

An advantage of the plastic pin gas generator according to the invention is that the plastic housing comprises detection / marking elements and / or components that are readily miscible or incorporated into the plastic housing material. The advantage of this incorporation lies mainly in the easier detection of products and in the restriction of the possibility of misuse of MGG-based pyrotechnic articles for purposes other than those for which they are intended, ie passive safety systems for automobiles or vehicles. other systems requiring rapid generation of gases to perform work. Composite glass fibers can be used as a marking component.

An advantage of the method of manufacturing a plastic pin gas generator according to the invention is the one-step preparation by spraying the plastic onto the initiator reinforcement pad while forming a plastic casing for the propellant. The method according to the invention is therefore advantageous by reducing the number of technological operations leading to the formation of a compact unit.

The plastic pin gas generator according to the invention has a standard external shape and a connector interface required by the application, but the folding system together with the flexible technology makes it a highly variable product with new possibilities. These include, in particular, the possibility of changing the type of initiator used, the possibility of increasing the overall robustness of the gas generator against the effect of back pressure and the possibility of influencing the interior space of the MGG, which indicates the maximum usable amount of gas generating agent. An indisputable advantage will also be the higher hermetic tightness and higher safety of the plastic pin gas generator according to the invention.

Compared to the lead version of MGG, the gas generator according to the invention provides an improvement in the overall increase in back pressure resistance and, as already mentioned, also a considerable advantage in the form of simpler technology. Compared to conventional MGG, either pin or leadwire, the plastic pin gas generator according to the invention is a cheaper alternative due to the materials used.

Clarification of drawings

Specific embodiments of the plastic pin gas generator according to the invention are shown in the accompanying drawings, in which:

- Fig. 1 - universal plastic pin gas generator in combination with hermetically sealed type of electric initiator, reinforced igniter

FIG. 2 shows another example of a plastic pin gas generator according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

The plastic pin gas generator according to FIG. 1 is formed by a holder 1 with contacts 2 carrying the pyrotechnic composition 3 such that the holder 1 is fixed to the metal reinforcement insert 5 and this assembly is surrounded by plastic material forming the base 4a, bottom 4b and body 4c of the casing 4. As a plastic material, a PPA-based thermoplastic filled with composite glass fibers containing a marking additive for identification of a given batch is used herein. The housing 4 defines the space of the chamber 7 filled with the propellant and hermetically sealed with a plastic cap 6 from above.

The production process of this pin gas generator is such that the metal reinforcement insert 5, together with the holder 1 of the pyrotechnic composition 3, is fixed in an injection mold preheated to a prescribed temperature corresponding to the thermoplastic used. This mold is then sealed and the thermoplastic melt is injected into the mold to form the plastic sleeve 4 in the sense of FIG. 1. This is a one-step spraying of the initiator with contacts 2 in the holder and on the reinforcement insert 5 while forming the plastic sleeve 4. the interior of which is a chamber 7 for the propellant. The chamber 7 is then filled with a propellant and then hermetically sealed with a plastic cap. Laser welding is used for closing.

Example 2

The plastic pin gas generator according to FIG. 2 is again formed by a holder 1 with contacts 2 carrying the pyrotechnic composition 3 such that the holder 1 is fixed to the metal reinforcement insert 5 and this assembly is surrounded by the plastic material forming the base 4a, bottom 4b and body 4c of the housing 4. As a plastic material there is used a thermoplastic based on PBT, filled with sandwich micro-bodies as detection additives. The housing 4 again defines the space of the chamber 7 filled with propellant and hermetically sealed with an Al-foil cap 6 from above.

The production process of the pin gas generator is such that the metal reinforcement insert 5, together with the holder 1, is fixed in injection mold preheated to a temperature corresponding to the thermoplastic used herein. This mold is then closed and the melt of the thermoplastic is injected into the mold, thereby forming a plastic sleeve 4 in the sense of FIG. 2. Also, there is also a one-step spraying of the initiator with contacts 2 in the holder 1 on the reinforcement insert 5. the interior of which is a chamber 7 for the propellant. The chamber 7 is then filled with a propellant and then hermetically sealed with a metal cap 6 based on Al. Thermal sealing is used for closing.

Another possibility of closing the chamber 7 is, for example, a glue over with a metal foil provided with an adhesive layer.

Industrial applicability

The invention is applicable in the field of passive protection of a vehicle occupant as part of a belt pretensioner. With respect to the use of the propellant as a gas generating agent, the present invention can also be used for other applications associated with, for example, a car anti-theft system.

Claims (9)

PATENT CLAIMS A plastic pin gas generator comprising a holder, contacts and initiator, characterized in that the holder (1) carrying the contacts (2) and the pyrotechnic composition (3) is housed in a plastic housing (4), the material of which comprises detection and / or or a marking element or component, wherein the base (4a) and the bottom (4b) of the housing (4) are surrounded from the outside by a reinforcement insert (5) and the housing (4c) of the housing (4) is provided with a cap (6) the periphery being tightly connected to the body (4c) of the housing (4) with which it forms an integral enclosed space of the propellant chamber (7). Plastic pin gas generator according to claim 1, characterized in that the plastic housing (4) is made of a thermoplastic based on PPA and / or PBT and has a body wall thickness (4c) of 0.5 to 2.0 mm and a bottom thickness. (4b) 0.4 to 2.5 mm. - 3 GB 305260 B6 Plastic pin gas generator according to claim 1, characterized in that the plastic housing (4) comprises sandwich micro-bodies as detection elements and / or the plastic housing (4) comprises composite glass fibers as a marking component. Plastic pin gas generator according to claim 1, characterized in that the reinforcement insert (5) is made of a metallic material. Plastic pin gas generator according to claim 1, characterized in that the cap (6) with a basic thickness of 0.1 to 3.0 mm is made of plastic and its connection to the body (4c) of the plastic housing (4) is made by laser or by heat welding. Plastic pin gas generator according to claims 1 to 6, characterized in that the cap (6) has a thickness reduced to 0.8 to 0.05 mm in its central region. Plastic pin gas generator according to claim 1, characterized in that the cover (6) is formed by a metal foil and its connection with the body (4c) of the plastic sleeve (4) is provided by an adhesive layer. Plastic pin gas generator according to claim 1, characterized in that the cap (6) is formed by a metal foil and its connection to the body (4c) of the plastic casing (4) is by heat welding. Method for producing a plastic pin gas generator according to claim 1, characterized in that the holder (1) with the contacts (2) and the initiator (3) is provided with a strengthening insert (5) and this assembly is inserted into a preheated injection mold. the plastic sleeve (4) is sprayed from the melt, after cooling the plastic sleeve (4) and pouring the propellant into the chamber (7), the cover (6) is placed from above, which is tightly connected to the sleeve (4) by laser or heat welding or metal tape.