Hybrid inflator and vehicle safety system comprising said hybrid inflator as well as method of forming a shock wave

Patent metadata

Field	Value
Publication number	US-2017166162-A1
Application number	US-201615368778-A
Country	US
Kind code	A1
Filing date	Dec 5, 2016
Priority date	Dec 10, 2015
Publication date	Jun 15, 2017
Grant date	—

Abstract

The invention relates to a hybrid inflator ( 10 ) includes at least one combustion chamber ( 15 ) in which propellant charge is arranged and which has a discharge end ( 20 ), the propellant charge being formed of at least one propellant element ( 26 ), at least one igniting unit ( 12 ) by which the propellant charge can be ignited. The hybrid inflator ( 10 ) also includes at least one bursting element ( 14, 14′, 14 ″) which in the inactivated state of the hybrid inflator ( 10 ) delimits the combustion chamber ( 15 ) against a gas supply chamber ( 16 ) at the discharge end ( 20 ). The bursting element ( 14, 14′, 14 ″) and a restraint element ( 18, 18′, 18 ″) maintain the propellant charge in its position and/or the bursting element ( 14, 14′, 14 ″) and the propellant charge delimit a shock gas volume (SGV), wherein in the activated state of the hybrid inflator ( 10 ) the shock gas volume (SGV) acts on the bursting element ( 14, 14′, 14 ″) like a gas pressure spring.

First claim

1 . A hybrid inflator ( 10 ) comprising:
at least one combustion chamber ( 15 ) in which propellant charge is arranged and which includes a discharge end ( 20 ), wherein the propellant charge is formed of at least one propellant element ( 26 ), at least one igniting unit ( 12 ) by which the propellant charge can be ignited, and comprising at least one bursting element ( 14 , 14 ′, 14 ″) which in the inactivated state of the hybrid inflator ( 10 ) delimits the combustion chamber ( 15 ) against a gas supply chamber ( 16 ) at the discharge end ( 20 ), wherein the bursting element ( 14 , 14 ′, 14 ″) and a restraint element ( 18 18 ′, 18 ″) maintaining the propellant charge in its position and/or the bursting element ( 14 , 14 ′, 14 ″) and the propellant charge delimit a shock gas volume (SGV) which in the activated state of the hybrid inflator ( 10 ) acts on the bursting element ( 14 , 14 ′, 14 ″) like a gas pressure spring.

2 . The hybrid inflator ( 10 ) according to claim 1 , wherein the bursting element ( 14 , 14 ′, 14 ″) includes an opening area ( 36 ) by which a shock wave can be generated, wherein between the opening area ( 36 ) and the igniting unit ( 12 ) the propellant charge is arranged so that a free space, especially a shock gas volume (SGV), is configured which is free from propellant charge and has an axial length (in parallel to the longitudinal hybrid inflator axis L) of at least 9 mm, preferably of at least 15 mm, especially preferably of at least 25 mm, and further especially preferably of at least 40 mm.

3 . The hybrid inflator ( 10 ) according to claim 1 , wherein the ratio of the shock gas volume (SGV) to the total empty volume of the combustion chamber (BKV) is at least 0.25, preferably 0.35, especially preferred 0.45, and/or wherein the hybrid inflator ( 10 ) includes an outer housing ( 11 ) having a constriction ( 17 ) formed between the combustion chamber ( 15 ) and the gas supply chamber ( 16 ), wherein the bursting element ( 14 ′), especially in the form of a bursting sleeve, is inserted in the constriction ( 17 ), wherein especially the bursting element ( 14 , 14 ′) projects in the longitudinal hybrid inflator axis (L) from the combustion chamber ( 15 ) into the gas supply chamber ( 16 ), especially through the constriction ( 17 ).

4 . The hybrid inflator ( 10 ) according to claim 1 , wherein the combustion chamber screen ( 18 ′) includes a peripheral wall ( 35 ) in which the combustion chamber ( 15 ) is arranged, wherein the peripheral wall ( 35 ) comprises a hollow-cylindrical portion and/or a hollow truncated portion and/or a hollow truncated pyramid portion, wherein preferably the restraint element ( 18 ′) is configured as combustion chamber screen ( 18 ′) comprising especially a universal ball joint-type portion ( 34 ) which is connected to the peripheral wall ( 35 ) especially on the combustion chamber side, wherein preferably the peripheral wall ( 35 ) has such longitudinal extension (L 1 ) which corresponds at least to the longitudinal extension (L 2 ) of a/the universal ball joint-type portion ( 34 ), preferably to 1.2 times, 2.5 times, especially to 1.5 times-2.0 times, the longitudinal extension (L 2 ) of a/the universal ball joint-type portion ( 34 ).

5 . The hybrid inflator ( 10 ) according to claim 1 , wherein the restraint element is a hollow cylindrical or hollow conical screen, especially a spring ( 18 ″), preferably a coil spring, wherein especially one end ( 25 ) of the spring ( 18 ″) is arranged in the bursting element ( 14 , 14 ′, 14 ″).

6 . The hybrid inflator ( 10 ) according to claim 1 , wherein at least one propellant element ( 26 ) is in the form of plural propellant rings ( 26 ), wherein the propellant rings ( 26 ) are arranged so that they form a passage ( 27 ) delimiting at least portions of the shock gas volume (SGV).

7 . The hybrid inflator ( 10 ) according to claim 6 , wherein the propellant rings ( 26 ) are designed and arranged so that for an entirety of plural propellant rings ( 26 ) a rib-shaped structure, viewed in the axial cross-section, having preferably U-shaped or V-shaped clearances ( 37 ) is formed, with especially the thickness of the propellant rings ( 26 ) being reduced from the outer periphery thereof toward the center thereof so that preferably the propellant rings ( 26 ) can be ignited by the igniting unit ( 12 ) so that hot igniting gases and/or igniting particles can be supplied to the clearances ( 37 ).

8 . The hybrid inflator ( 10 ) according to claim 1 , wherein between the igniting unit ( 12 ) and a first propellant ring ( 28 ) of the propellant charge in the gas flow direction (G) of the combustion chamber ( 15 ) a preferably annular filling material ( 29 ), which of preference is made of closed-pore silicone foam, is arranged, and/or between the bursting element ( 14 , 14 ′, 14 ″) and a last propellant ring ( 30 ) of the propellant charge in the gas flow direction (G) of the combustion chamber ( 15 ) a preferably annular spacer ( 31 ) is arranged.

9 . The hybrid inflator ( 10 ) according to claim 1 , wherein the ratio of the shock gas volume (SGV) to an area (n*(rGVK) 2 ) defined by the radius (rGVK) of the inner diameter of the gas supply chamber ( 16 ) is larger than 1 cm.

10 . A vehicle safety system comprising a hybrid inflator ( 10 ) according to claim 1 , an airbag unit and/or a crash sensor.

11 . A method of forming a shock wave inside a hybrid inflator ( 10 ) according to claim 1 , the method comprising the following steps of:
activating an igniting unit ( 12 ), opening a bursting element ( 14 , 14 ′, 14 ″) by pressing a shock gas volume (SGV) formed ahead of the bursting element ( 14 , 14 ′, 14 ″) against the bursting element ( 14 , 14 ′, 14 ″) and generating a shock wave in a gas supply chamber ( 16 ) downstream of the bursting element ( 14 , 14 ′, 14 ″).

12 . The method according to claim 11 , wherein at least one of the following further steps of:
guiding gas generated in a combustion chamber ( 15 ) in the direction of the bursting element ( 14 , 14 ′, 14 ″), guiding the shock gas volume (SGV) into the gas supply chamber ( 16 ), igniting propellant charge present in the combustion chamber ( 15 ), while the gas is guided in the direction of the bursting element ( 14 , 14 ′, 14 ″), supplying hot igniting gases and/or igniting particles to clearances ( 37 ) formed between propellant rings ( 26 ).

Assignees

• Trw Airbag Sys Gmbh

Inventors

• Last Detlef
• Seidl Lorenz
• Ruckdeschel Rolf

Classifications

• B60R22/1954

  characterised by fluid actuators, e.g. pyrotechnic gas generators (actuating a cable B60R22/1952) · CPC title

• B60R21/274

  characterised by means to rupture or open the fluid source · CPC title

• B60R21/264

  using instantaneous generation of gas, e.g. pyrotechnic (B60R21/268 takes precedence) · CPC title

• B60R21/272 Primary

  with means for increasing the pressure of the gas just before or during liberation, e.g. hybrid inflators · CPC title

• B60R2021/2642

  comprising a plurality of combustion chambers or sub-chambers · CPC title