Gas generator

Abstract

A gas generator (1) is provided with a holder (10) and a cup (40) that accommodates a gas-generating agent. The holder (10) has a first recess (12) and an annular groove (16) provided in an end surface on the side facing the cup (40), a second recess (13) provided in an end surface on the opposite side, and a partition (14) that partitions the first recess (12) and the second recess (13). The bottom surface (12a) of the first recess (12) has a first bottom surface (12a1) and a second bottom surface (12a2) positioned further inward than the first bottom surface (12a1) and on the second recess (13) side. When the distance from the second bottom surface (12a2) to the bottom surface (13a) of the second recess (13) is A, the distance from the first bottom surface (12a1) to the bottom surface (13a) of the second recess (13) is B, and the distance from the bottom surface (13a) of the second recess (13) to the annular groove (16) is C, the gas generator (1) satisfies Alt; blt; and C, conditions.

Description

Technical Field

[0001] The present invention relates to a gas generator, and in particular to a small gas generator configured to generate a relatively small amount of gas during operation. Background Art

[0002] Conventionally, from the perspective of protecting passengers in automobiles, etc., seat belt devices as passenger protection devices have become popular. Seat belt devices are equipped for the purpose of protecting passengers from impacts that occur when vehicles collide, etc., and are devices that wrap seat belts around the passenger's body to restrain the passenger in the seat. This prevents the passenger from being thrown into or out of the vehicle when the vehicle collides.

[0003] In a seat belt device, a small gas generator called a micro gas generator is built into a device equipped with a so-called pretensioner. The pretensioner is a device that instantly retracts the slack of the seat belt caused by the thickness of clothing, etc. when a collision of a vehicle or the like is detected. This function is achieved by strongly pulling one end of the seat belt in with the pressure of the gas output from the gas generator.

[0004] Furthermore, when compared with a large gas generator called an inflator that is suitable for being incorporated into an airbag device, the total amount of gas generated by this small gas generator during operation is much smaller, and accordingly, the structure thereof is also greatly different.

[0005] As such a gas generator, there are, for example, a structure disclosed in Japanese Patent Publication No. 2008-37389 (Patent Document 1) and a structure disclosed in Japanese Patent Publication No. 2022-36022 (Patent Document 2). The gas generators disclosed in the above Patent Documents 1 and 2 include: a substantially cylindrical cup with a bottom, filled with a gas generating agent that generates gas by combustion; an igniter for burning the gas generating agent; and a substantially cylindrical retainer that is coaxially assembled to the cup to close the open end of the cup and retains the igniter in a manner facing the gas generating agent.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2008-37389

[0009] Patent Document 2: Japanese Patent Application Publication No. 2022-36022 Summary of the invention

[0010] Problems to be solved by the invention

[0011] Here, the retainer is used to hold the igniter and assemble the cup as described above, so a first recess for receiving and holding the igniter and an annular groove for receiving and holding the opening edge of the cup are provided on one axial end face of the retainer. In addition, since a connector for connecting the igniter to the outside needs to be installed in a pluggable manner in the retainer, a second recess for receiving and holding the connector is provided on the other axial end face of the retainer.

[0012] There is a strong demand for improving the mountability of the pretensioner in the gas generator, and to achieve this improvement, miniaturization and lightness of the pretensioner and, in turn, the gas generator has become an important issue. Here, the retainer made of metal material is a part with a high weight relative to the total weight among the parts constituting the gas generator, so attempts have been made to miniaturize and lighten the gas generator by changing the material, shape, wall thickness, etc.

[0013] However, the retainer is also a component that is subjected to high pressure when the gas generator is operated, so it is necessary to ensure high mechanical strength (i.e., pressure resistance). For example, when the gas generator is operated, the gas generated by the gas generator is introduced into the operating space of the pretensioner module installed in the seat belt device, but at this time, the internal pressure of the operating space becomes very high, and this high pressure acts on the retainer. Here, if the mechanical strength of the retainer is insufficient, it cannot withstand the high pressure and the retainer is damaged, resulting in an undesirable situation such as gas leakage from the damaged part.

[0014] As described above, in order to realize stable operation of the above-mentioned gas generator, it is essential to ensure high pressure resistance performance while achieving size reduction and weight reduction.

[0015] On the other hand, in the above-mentioned gas generator, the increase of output has also become an important issue. In this regard, it is also possible to consider increasing the filling amount of the gas generating agent by increasing the volume in the cup, but it is not easy to take into account the resulting increase in output and the above-mentioned pressure resistance and the compactness and lightness.

[0016] Therefore, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a gas generator which has high output and high withstand pressure and is also compact and lightweight.

[0017] Organizations used to solve problems

[0018] The gas generator according to the present invention includes: a gas generating agent that generates gas by combustion; an igniter having an ignition portion filled with an igniting powder and a terminal pin connected to the ignition portion; a bottomed substantially cylindrical cup that houses the gas generating agent and has one end in the axial direction configured as an open end; and a substantially cylindrical holder that is coaxially assembled by the cup to close the open end and holds the igniter with the ignition portion facing the gas generating agent. The holder has an axial end face on the side facing the cup, a first recess for receiving and holding the igniter, an axial end face on the side not facing the cup, a second recess for arranging the terminal pin and receiving and holding a connector for external connection of the igniter via the terminal pin, a partition portion that separates the first recess from the second recess by defining the bottom surface of the first recess and the bottom surface of the second recess, and an annular groove portion provided on the axial end face on the side facing the cup for receiving and holding the opening edge of the cup inserted along the axial direction. The bottom surface of the first recess has a stepped shape, and in a view along the axial direction of the holder, the bottom surface of the first recess has an outer annular first bottom surface and a second bottom surface located inside the first bottom surface and on the side of the second recess with respect to the first bottom surface. In the gas generator according to the present invention, when the distance from the second bottom surface to the bottom surface of the second recess is A, the distance from the first bottom surface to the bottom surface of the second recess is B, and the distance from the bottom surface of the second recess to the annular groove portion is C, the condition A < B < C is satisfied.

[0019] Advantages of the Invention

[0020] According to the present invention, it is possible to provide a gas generator with high output, high pressure resistance, and further miniaturization and weight reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic cross-sectional view of a gas generator according to an embodiment.

[0022] Figure 2 is Figure 1 an enlarged view of the area II shown in

[0023] Figure 3 is a schematic cross-sectional view showing a state in which a pretensioner housing is attached to the gas generator shown in Figure 1 the gas generator.

[0024] Figure 4 is a schematic cross-sectional view showing a method of assembling a short-circuit clip to the gas generator shown in Figure 1 the gas generator.

[0025] Figure 5 is a schematic cross-sectional view showing a state in which a pretensioner housing is attached to the gas generator shown in Figure 1The diagram is a schematic cross-sectional view of a gas generator in a state where a short-circuit clip is assembled.

[0026] Figure 6 It is a schematic cross-sectional view of a gas generator related to a comparative example.

[0027] Figure 7 This is a schematic cross-sectional view showing a state in which a housing of a pretensioner is assembled to a gas generator according to a modified example. DETAILED DESCRIPTION

[0028] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments shown below illustrate a case where the present invention is applied to a gas generator (so-called micro gas generator) appropriately incorporated into a seat belt device having a pretensioner. In the embodiments shown below, the same reference numerals are given to the same or common parts in the drawings, and their description will not be repeated.

[0029] (Implementation Method)

[0030] Figure 1 It is a schematic cross-sectional view of a gas generator according to an embodiment. Figure 2 yes Figure 1 An enlarged view of region II is shown. Figure 3 (A) means Figure 1 A schematic cross-sectional view of a state in which the gas generator is attached to the housing of the pretensioner, Figure 3 (B) means Figure 3 (A) is a schematic cross-sectional view of another embodiment of the pretensioner. Figures 1 to 3 , the structure of the gas generator 1 according to the present embodiment will be described.

[0031] like Figure 1 As shown, gas generator 1 of the present embodiment mainly includes a retainer 10 , an igniter 20 , a sealing member 30 , a cup 40 , and a gas generating agent 50 .

[0032] The retainer 10 and the cup 40 are coaxially combined to form a housing that is an outer shell of the gas generator 1. The igniter 20 is retained by the retainer 10, and the cup 40 is assembled to the retainer 10 in a manner that covers the igniter 20. In addition, the gas generating agent 50 is accommodated in a space defined by the retainer 10, the igniter 20, and the cup 40.

[0033] The retainer 10 is a member for retaining the igniter 20 and the cup 40 and has a substantially cylindrical shape. Here, in the present embodiment, since the retainer 10 is provided with the first recess 12, the second recess 13 and the opening 14a described later, the retainer 10 substantially has a substantially cylindrical shape.

[0034] The retainer 10 is also a component constituting a part of the housing as described above, and is formed of a formed product made of a metal material such as aluminum or an aluminum alloy. The retainer 10 is formed into a shape as shown in the figure by, for example, performing one or more forging processes, punching processes, cutting processes, etc. on a plate-shaped metal component or a rod-shaped metal component as a raw material in a predetermined order.

[0035] The retainer 10 has a cylindrical body 11 defining an outer peripheral surface, and a first recess 12 and a second recess 13 are provided in the body 11. A partition 14 is formed in the portion of the body 11 located between the first recess 12 and the second recess 13 to separate the first recess 12 and the second recess 13, and a locking portion 15 is formed in the portion of the body 11 located closer to a bottom wall 42 of the cup 40 to be described later than the partition 14.

[0036] The body portion 11 includes a first cylindrical body portion 11 a provided at an axial end portion facing the cup 40 , and a second cylindrical body portion 11 b provided at an axial end portion not facing the cup 40 .

[0037] The first body portion 11 a surrounds the partition portion 14 , an end portion of the first recess 12 on the partition portion 14 side in the axial direction of the cage 10 , and an end portion of the second recess 13 on the partition portion 14 side in the axial direction.

[0038] The second body portion 11b is provided to protrude from the axial end portion of the first body portion 11a on the side not facing the cup 40, and its outer shape along the radial direction is configured to be smaller than that of the first body portion 11a. In addition, the second body portion 11b surrounds the end portion of the retainer 10 in the second recess 13 on the axial direction opposite to the partition portion 14 side.

[0039] The first recess 12 is a portion for receiving and holding a base portion 21 of the igniter 20, which will be described later, and is provided on the axial end surface of the body 11 on the side facing the cup 40. The bottom surface 12a of the first recess 12 is defined by the partition 14, and the inner side surface 12b of the first recess 12 is mainly defined by the locking portion 15.

[0040] The bottom surface 12a of the first recess 12 has a stepped shape. Thus, when viewed along the axial direction of the retainer 10, the bottom surface 12a of the first recess 12 includes an annular first bottom surface 12a1 located on the outside of the bottom surface 12a, and a second bottom surface 12a2 located on the inside of the first bottom surface 12a1 and on the second recess 13 side.

[0041] The second recess 13 is a portion where a pair of terminal pins 23 of the igniter 20, which will be described later, are arranged and a connector (not shown) for external connection of the igniter 20 is received and held via the pair of terminal pins 23, and is provided on the axial end surface of the body 11 on the side not facing the cup 40. The bottom surface 13a of the second recess 13 is defined by the partition 14, and the inner side surface 13b of the second recess 13 is defined by a cylindrical portion of the body 11.

[0042] The partition 14 is provided with an opening 14a so as to communicate with the first recess 12 and the second recess 13. The opening 14a is a portion through which the pair of terminal pins 23 are inserted (more strictly speaking, a portion into which the pair of terminal pins 23 and the lower end portion of the base 21 of the igniter 20 covering the pair of terminal pins 23 are inserted).

[0043] The locking portion 15 is a portion for caulking and fixing the base portion 21 of the igniter 20. The locking portion 15 has an annular plate shape. The distal end of the locking portion 15 is bent inward, thereby fixing the igniter 20 accommodated in the first recess 12 to the holder 10 in an immovable manner.

[0044] Here, if Figure 2 As shown, an annular groove portion 16 and an annular protruding edge portion 17 are provided on the axial end surface of the first body portion 11 a on the side facing the cup 40 so as to surround the locking portion 15 .

[0045] The annular groove 16 is a portion for receiving and holding a flange 43 of the cup 40 inserted in the axial direction. The annular groove 16 is provided so that its bottom surface 16a is located closer to the bottom wall 42 of the cup 40 than the partition 14.

[0046] The annular protrusion 17 is a portion for caulking and fixing the flange portion 43 of the cup 40, and has an annular plate shape protruding from the first body portion 11a toward the ignition portion 22 side to define the outer wall surface of the annular groove portion 16. In addition, the annular protrusion 17 has a tip side portion bent inward, thereby fixing the cup 40 to the retainer 10 in an immovable manner.

[0047] Here, if Figure 1 As shown, in the gas generator 1 according to the present embodiment, when the axial length of the second body portion 11b is D and the sum of the axial length of the annular flange portion 17 of the cup 40 in the state of being assembled to the retainer 10 along the first body portion 11a and the axial length of the first body portion 11a is E, the condition of E<1.8×D is satisfied. Thus, the axial length of the second body portion 11b can be made relatively long.

[0048] In addition, when the depth of the second recessed portion 13 is F, the condition of F<1.8×D is satisfied. Thus, the axial length of the second body portion 11 b can also be made relatively long.

[0049] The igniter 20 is used to generate flames and is also called a squib. The igniter 20 has a base 21, an ignition portion 22, and a pair of terminal pins 23 (see Figure 4 The base 21 is a portion that holds the ignition portion 22 and the pair of terminal pins 23, and is also a portion that is fixed to the retainer 10. The base 21 is held by the pair of terminal pins 23 being inserted through it. Figure 1 In the drawing, since a pair of terminal pins 23 are overlapped and positioned in a direction perpendicular to the paper surface, only one side thereof is shown.

[0050] The ignition unit 22 includes therein ignition powder that ignites and burns to generate flames when operated, and a resistor (bridge wire) for igniting the ignition powder. A pair of terminal pins 23 are connected to the ignition unit 22 to ignite the ignition powder.

[0051] In more detail, the ignition portion 22 includes a detonating cup formed in a cup shape, and has the following structure: the above-mentioned resistor is installed in a manner to connect the ends of a pair of terminal pins 23 inserted into the detonating cup, and ignition powder is filled in the detonating cup in a manner to surround the resistor or close to the resistor.

[0052] Here, the resistor is usually made of nickel-chromium heat-resistant alloy wire, and the ignition powder is usually made of ZPP (zirconium potassium perchlorate), ZWPP (zirconium tungsten potassium perchlorate), lead trinitroresorcinate, etc. The detonator cup is usually made of metal or plastic.

[0053] When a collision is detected, a predetermined amount of current flows through the resistor via the terminal pin 23. By flowing a predetermined amount of current through the resistor, Joule heat is generated in the resistor, and the ignition powder starts to burn. The high-temperature flame generated by the combustion ruptures the detonator cup containing the ignition powder. The time from the flow of current through the resistor to the operation of the igniter 20 is generally less than 2 ms when the resistor uses a nickel-chromium heat-resistant alloy wire.

[0054] When assembling the igniter 20 to the holder 10, the igniter 20 is inserted into the first recess 12 from the axial end of the holder 10 on the side where the first recess 12 is provided, so that the pair of terminal pins 23 are inserted into the opening 14a provided in the partition 14. As a result, the base 21 is accommodated in the first recess 12 and the opening 14a, and the pair of terminal pins 23 are arranged in the second recess 13. In this state, by bending the end side of the locking portion 15 toward the base 21 side, the base 21 is clamped by the partition 14 and the locking portion 15, and the igniter 20 is fixed to the holder 10 by caulking.

[0055] Therefore, ignition portion 22 of igniter 20 is located closer to bottom wall portion 42 of cup 40 than the axial end surface of retainer 10 on the side where first recess 12 is provided, and ignition portion 22 faces gas generating agent 50 accommodated in accommodation space 44 of cup 40 described later.

[0056] Here, a sealing member 30 composed of an O-ring or the like is pre-accommodated in the first recess 12 of the retainer 10, and the gap generated between the retainer 10 and the igniter 20 is sealed by the sealing member 30. More specifically, the sealing member 30 is positioned so as to be sandwiched between the partition 14 and the locking portion 15 of the retainer 10 and the base 21 of the igniter 20, and the sealing member 30 is compressed by the retainer 10 and the igniter 20, thereby ensuring the sealing between them.

[0057] In addition, as the sealing member 30, it is preferable to use a member having sufficient heat resistance and durability, and for example, an O-ring made of EPDM, which is a type of ethylene propylene rubber, can be preferably used.

[0058] Cup 40 is a bottomed cylindrical member with one axial end formed as an open end 41a, and has sidewall 41, bottom wall 42, and flange 43. Gas generating agent 50 is accommodated in accommodation space 44 of cup 40 defined by sidewall 41 and bottom wall 42.

[0059] The open end 41a is formed by the end opposite to the bottom wall 42 of the pair of axial ends of the side wall 41. The flange 43 is located so as to extend outward from the open end 41a. The flange 43 is a portion for fixing the cup 40 to the holder 10.

[0060] The bottom wall 42 of the cup 40 is provided with a notch 42a by forming a groove-shaped cutout portion on its surface. The notch 42a is provided to form a fragile portion that is more fragile than other positions at a predetermined position of the bottom wall 42. By providing the notch 42a, the cup 40 can be configured so that when the gas generator 1 is operated, the cup 40 opens with the portion as a starting point.

[0061] The cup 40 is also a member constituting a part of the housing, and is formed of a molded product made of a metal material such as aluminum, aluminum alloy, or iron-based material such as stainless steel. In addition, the cup 40 is generally molded by press working using a metal mold.

[0062] As described above, the cup 40 is assembled to the cage 10 by caulking and fixing the flange portion 43 to the annular protrusion portion 17 provided on the cage 10 .

[0063] More specifically, first, the flange portion 43 of the cup 40 is inserted into the annular groove portion 16 provided in the retainer 10. Figure 2 As shown, of the pair of faces of the flange portion 43 of the cup 40 located in the axial direction, the first face 43a located on the retainer 10 side abuts against the bottom face 16a of the annular groove portion 16. In addition, at this time, the inner peripheral face of the side wall portion 41 of the cup 40 is attached to the inner wall face 16c of the annular groove portion 16.

[0064] Next, the tip end side portion of the annular flange portion 17 of the retainer 10 is bent inward. As a result, the annular flange portion 17, except for the root side portion (i.e., the portion connected to the first body portion 11a), is tilted toward the bottom surface 16a side of the annular groove portion 16 as a whole, and is bent toward the flange portion 43 of the cup 40 as described above.

[0065] Therefore, if Figure 2 As shown, the tip end side portion of the annular protrusion 17 abuts against the second surface 43b located on the opposite side of the first surface 43a of the flange 43, among the pair of faces located in the axial direction. Therefore, the flange 43 is clamped in the axial direction of the cup 40 by the tip end side portion of the annular protrusion 17 and the bottom surface 16a of the annular groove 16. Thus, the open end 41a of the cup 40 is closed by the retainer 10 (more strictly speaking, by the igniter 20, etc.).

[0066] The gas generating agent 50 generates a large amount of gas by being ignited and burned by the igniter 20. As the gas generating agent 50, a molded body of smokeless powder (nitrocellulose), a molded body of a non-azid composition formed of an organic nitrogen compound and an oxidant, etc. are used. In recent years, non-nitrocellulose-based gas generating agents that generate very little harmful substances such as carbon monoxide have attracted attention as the gas generating agent 50.

[0067] As the molded body of the gas generator 50, various shapes such as granular, pellet, cylindrical, and disc-shaped molded bodies can be used. In addition, porous molded bodies (such as macaroni-shaped, lotus root-shaped, etc.) with through holes can also be used as the molded body of the gas generator 50. The optimal shape is selected according to the specifications of the pretensioner to be assembled with the gas generator 1. In addition, in addition to the shape, the linear combustion speed, pressure index, etc. are also taken into consideration to select the size of the molded body of the gas generator 50. In addition, the filling amount of the gas generator 50 can be appropriately changed according to the specifications of the pretensioner to be assembled, but when smokeless gunpowder is used, it is generally set to about 0.1g to 2.0g.

[0068] like Figure 2As shown, in the gas generator 1 according to the present embodiment, as described above, the bottom surface 12a of the first recess 12 defined by the partition portion 14 includes a first bottom surface 12a1 and a second bottom surface 12a2, and the second bottom surface 12a2 is located closer to the second recess 13 than the first bottom surface 12a1. Thus, the distance B from the first bottom surface 12a1 of the first recess 12 to the bottom surface 13a of the second recess 13 is configured to be larger than the distance A from the second bottom surface 12a2 of the first recess 12 to the bottom surface 13a of the second recess 13.

[0069] In addition, in the gas generator 1, as described above, the annular groove portion 16 is provided such that its bottom surface 16a is located closer to the bottom wall portion 42 of the cup 40 than the partition portion 14. Thus, the distance C from the bottom surface 13a of the second recess 13 to the annular groove portion 16 is configured to be larger than the distance B.

[0070] That is, in the gas generator 1 according to the present embodiment, when the distance from the second bottom surface 12a2 of the first recess 12 to the bottom surface 13a of the second recess 13 is set as A, the distance from the first bottom surface 12a1 of the first recess 12 to the bottom surface 13a of the second recess 13 is set as B, and the distance from the bottom surface 13a of the second recess 13 to the annular groove portion 16 is set as C, the condition A < B < C is satisfied.

[0071] By configuring in this way, a gas generator with high output, high pressure resistance, and further achieving miniaturization and weight reduction can be made, which will be described in detail later.

[0072] As Figure 3 (A) shows, when the gas generator 1 is loaded into the pretensioner 200 provided in the seat belt device, the substantially cylindrical housing 201 of the pretensioner 200 is assembled to the gas generator 1. More specifically, first, the housing 201 is inserted into the retainer 10 from the axial end on the side of the first recess 12 of the retainer 10 so as to surround the first body portion 11a. Thus, the stepped portion provided on the inner peripheral surface of the housing 201 abuts against the axial end surface of the first body portion 11a on the side of the bottom wall portion 42 of the cup 40. In this state, by bending the end side portion of the housing 201 toward the second body portion 11b side, the housing 201 is caulked and fixed to the retainer 10. Thus, the housing 201 is assembled to the gas generator 1.

[0073] Here, as Figure 3 (B) shows, in another form of the pretensioner 200A of the pretensioner 200 according to Figure 3 (A) shown, in order to improve its pressure resistance performance, the housing 201A of the pretensioner 200A is configured to have a larger thickness than the housing 201 of the pretensioner 200.

[0074] Since the thickness of the housing 201A is made large, the end position of the housing 201A after assembly is moved toward the axial end surface side of the retainer 10 that does not face the cup 40. Figure 1 When the distance D) in the second recess 13 is set to be relatively short, the distal end of the housing 201A protrudes outward from the axial end surface of the retainer 10, thereby causing a problem that it becomes difficult to mount the connector to the second recess 13.

[0075] In this regard, in the gas generator 1 according to the present embodiment, as described above, the axial length ( Figure 1 The distance D) in the figure is set to be relatively long, so the above-mentioned problem can be prevented from occurring.

[0076] Figure 4 It means short circuit Figure 1 A schematic cross-sectional view of the assembly method of the gas generator shown, Figure 5 It means in Figure 1 The schematic cross-sectional view of the gas generator shown in FIG. Figure 4 and Figure 5 , a method for assembling the short-circuit clip 100 to the gas generator 1 of this embodiment will be described. Figure 4 In FIG. 1 , only the short-circuit clip 100 is shown in a side view. Figure 4 , the gas generator 1 is shown in a top view and in Figure 1 A cross section orthogonal to the cross section represented in .

[0077] In the gas generator 1 configured as described above, a short-circuit clip 100 is used to prevent the gas generator 1 from malfunctioning due to electrostatic discharge or the like before being mounted on a vehicle, for example, during transportation for shipment of the gas generator 1. The short-circuit clip 100 is assembled in the gas generator 1 to intentionally short-circuit a pair of terminal pins 23 of the igniter 20.

[0078] like Figure 4 As shown, when the short-circuit clip 100 is assembled to the gas generator 1, the short-circuit clip 100 is inserted into the second recess 13 of the retainer 10. At this time, the plurality of claws 101 protruding outward from the side surface of the short-circuit clip 100 engage with the plurality of recessed portions 13b1 provided on the inner side surface 13b of the second recess 13. By this engagement, the short-circuit clip 100 is fixed to the second recess 13.

[0079] like Figure 5 As shown, the short-circuit clip 100 is fixed to the second recess 13, so that the two leaf spring portions 102 provided in the short-circuit clip 100 are respectively pressed against the pair of terminal pins 23. Thus, the gas generator 1 is maintained in the short-circuited state.

[0080] Next, refer to Figure 1 The operation of gas generator 1 according to the present embodiment during operation will be described.

[0081] Reference Figure 1 When a vehicle equipped with the gas generator 1 of this embodiment collides, a collision detection mechanism separately provided in the vehicle detects the collision, and the igniter 20 is actuated based on the collision. The igniter 20 is actuated, and the ignition charge contained in the ignition portion 22 is ignited and burns, thereby rupturing the detonator cup.

[0082] The detonation cup ruptures, and the flame generated by the combustion of the ignition charge jets toward the storage space 44 containing the gas generator 50. The gas generator 50 is ignited and burns by the flame, and a large amount of gas is generated in the storage space 44. The internal pressure of the storage space 44 rises rapidly by the combustion of the gas generator 50, and the bottom wall 42 of the cup 40 opens with the notch 42a as the starting point, and the generated large amount of gas is discharged to the outside of the gas generator 1.

[0083] Then, a large amount of gas discharged from the gas generator 1 is introduced into the operating space of the pretensioner in which the gas generator 1 is installed, whereby the pretensioner is driven and one end of the seat belt provided in the seat belt device is strongly pulled in.

[0084] Here, as described above, the internal pressure of the housing space 44 increases due to the operation of the gas generator 1, and the igniter 20 is pressed against the partition 14. Thus, a large external force is applied to the retainer 10 defining the partition 14 and its vicinity.

[0085] At this time, since the igniter 20 and the partition 14 located in the radially inner part (i.e., the partition 14 defining the second bottom surface 12a2 of the first recess 12) are in surface contact with each other while ensuring a relatively large area, a large stress is not likely to be generated in this part of the partition 14. On the other hand, since the igniter 20 and the partition 14 located in the radially outer part (i.e., the partition 14 defining the first bottom surface 12a1 of the first recess 12) and the retainer 10 defining the vicinity thereof are partially in contact, a large stress is generated in this part of the retainer 10.

[0086] Therefore, the pressure resistance of cage 10 is not determined by the mechanical strength of the radially inner portion of partition 14 but by the mechanical strength of the radially outer portion of partition 14 and the portion of cage 10 defining the vicinity thereof.

[0087] Regarding this, in the gas generator 1 according to the present embodiment, as described above, the distance B from the first bottom surface 12a1 of the first recess 12 to the bottom surface 13a of the second recess 13 (see Figure 2 ) is configured to be larger than the distance A from the second bottom surface 12a2 of the first recess 12 to the bottom surface 13a of the second recess 13 (see Figure 2 ). Thereby, it is possible to improve the mechanical strength of the partition portion 14 of the portion that generates a large stress during the operation of the gas generator 1 as described above, that is, the portion located between the first bottom surface 12a1 and the bottom surface 13a.

[0088] Furthermore, by setting the distance B to a length that sufficiently ensures the mechanical strength of the partition portion 14 of the portion that generates a large stress during the above operation, the mechanical strength of the partition portion 14 as a whole is ensured.

[0089] On the other hand, in the case where A < B as described above, when the distance C from the bottom surface of the second recess to the annular groove portion (see Figure 2 ) is set to be equal to or less than the distance B, the mechanical strength of the holder of the portion located between the second recess and the annular groove portion determines the pressure resistance performance of the holder as a whole.

[0090] Regarding this, in the gas generator 1 according to the present embodiment, as described above, the distance C from the bottom surface 13a of the second recess 13 to the annular groove portion 16 is configured to be larger than the distance B. Thereby, the pressure resistance performance of the holder 10 is determined by the mechanical strength of the partition portion 14 of the portion that defines the distance B, that is, the portion located between the first bottom surface 12a1 and the bottom surface 13a. Furthermore, since the mechanical strength of this portion of the partition portion 14 is ensured, as a result, a gas generator 1 with excellent pressure resistance performance can be achieved.

[0091] In addition, in the case where B < C as described above, the arrangement position of the second recess 13 retreats in a direction away from the bottom wall portion 42 of the cup 40. Similarly, the arrangement positions of the first recess 12 and the partition portion 14 also retreat in a direction away from the bottom wall portion 42.

[0092] With such a configuration, the arrangement positions of the igniter 20 received and held by the first recess 12 and the connector received and held by the second recess 13 retreat in a direction away from the bottom wall portion 42. Therefore, by virtue of the accompanying increase in the volume of the accommodation space 44 of the cup 40, the filling amount of the gas generating agent 50 can be increased, and as a result, a high output of the gas generator 1 can be achieved.

[0093] Furthermore, in the case where B < C as described above, although the axial length of the second body portion 11b ( Figure 1The distance D) in it becomes slightly longer, but there is no need to make any special changes to the height of the cup 40 and the axial length of the first body portion 11a, so the gas generator 1 that is miniaturized and lightweight can be achieved.

[0094] Therefore, by making the gas generator 1 as in the present embodiment described above, a gas generator with high output, high pressure resistance, and miniaturization and lightweight can be achieved.

[0095] Hereinafter, by comparing with the gas generators of the comparative examples, the effects brought about by making the gas generator 1 of the present embodiment described above will be described. Figure 6 (A) and Figure 6 (B) are schematic cross-sectional views of the gas generators 1X1 and 1X2 of Comparative Examples 1 and 2, respectively.

[0096] As Figure 6 (A) shows, the gas generator 1X1 of Comparative Example 1 is configured such that the distance A from the second bottom surface of the first recess to the bottom surface of the second recess, the distance B from the first bottom surface of the first recess to the bottom surface of the second recess, and the distance C from the bottom surface of the second recess to the annular groove portion satisfy the condition of A < C < B. That is, the gas generator 1X1 of Comparative Example 1 has a stepped shape at the bottom surface 12a of the first recess 12, and the mechanical strength of the partition portion 14 of the portion located radially outside is improved. On the other hand, the mechanical strength of the retainer 10 of the portion located radially outside of the partition portion 14 of this portion is configured to be relatively low.

[0097] Here, when C < B as described above, the mechanical strength of the retainer of the portion between the second recess and the annular groove portion (that is, the retainer of the portion defining the distance C) determines the pressure resistance performance of the retainer as a whole. However, in the gas generator 1X1, due to the fact that the distance C is set relatively short and stress concentration is likely to occur at the corners of the second recess and the corners of the annular groove portion, etc., the mechanical strength of this portion of the retainer becomes relatively low, and as a result, it is difficult to ensure a relatively high pressure resistance performance of the retainer as a whole.

[0098] In contrast, when the gas generator 1 of the present embodiment is made, since B < C as described above, the mechanical strength of the partition portion 14 of the portion between the first bottom surface 12a1 of the first recess 12 and the bottom surface 13a of the second recess 13 (that is, the partition portion 14 of the portion defining the distance B) determines the pressure resistance performance of the retainer as a whole. In addition, the mechanical strength of this portion of the partition portion 14 is ensured. Therefore, by making the gas generator 1 of the present embodiment, pressure resistance performance superior to that of the gas generator 1X1 can be obtained.

[0099] In addition, compared with the gas generator 1X1 in which the distance C is set to be relatively short, the distance C of the gas generator 1 according to the present embodiment is set to be relatively long. Therefore, by forming the gas generator 1 according to the present embodiment, as described above, it is possible to increase the volume of the accommodation space 44 of the cup 40, so that a higher output can be achieved compared with the gas generator 1X1.

[0100] As Figure 6 (B) shows, the gas generator 1X2 according to Comparative Example 2 is configured to satisfy the condition of A = B < C. That is, in the gas generator 1X2 according to Comparative Example 2, since the bottom surface 12a of the first recess 12 does not have a stepped shape, the mechanical strength of the partition portion 14 of the portion located radially outside is not improved. On the other hand, the mechanical strength of the retainer 10 of the portion located radially outside of the partition portion 14 of this portion is configured to be relatively high, and the volume of the accommodation space 44 of the cup 40 is configured to be relatively large.

[0101] Here, when B < C as described above, the mechanical strength of the partition portion at the portion where the distance B is defined determines the pressure resistance performance of the entire retainer. However, in the gas generator 1X2, since A = B is set and the distance B is set to be relatively short, the mechanical strength of the partition portion of this portion becomes low, and as a result, it is difficult to ensure a relatively high pressure resistance performance of the entire retainer.

[0102] In contrast, when the gas generator 1 according to the present embodiment is formed, as described above, since A < B is set and the distance B is set to be long, the partition portion 14 at the portion where the distance B is defined can be formed into a structure that ensures mechanical strength. Therefore, by forming the gas generator 1, a pressure resistance performance superior to that of the gas generator 1X2 can be obtained.

[0103] In this way, by comparing with the gas generators 1X1 and 1X2 according to Comparative Examples 1 and 2, it can be understood that when the gas generator 1 according to the above-described embodiment is formed, a gas generator with high output, high pressure resistance, and further miniaturization and weight reduction can be formed.

[0104] (Modification example)

[0105] Figure 7 is a schematic cross-sectional view showing a state in which a pretensioner is assembled to the housing of the gas generator according to the modification example. Hereinafter, with reference to this Figure 7 the gas generator 1A according to the modification example based on the above-described embodiment will be described.

[0106] As Figure 7 shown, the gas generator 1A according to the modification example is different only in the structure of the retainer 10A when compared with the gas generator 1 according to the above-described embodiment.

[0107] More specifically, retainer 10A used in gas generator 1A according to the modified example includes first portion 10A1 formed of a resin member and second portion 10A2 formed of a metal member.

[0108] The first portion 10A1 defines the axial end portion of the retainer 10A on the side not facing the cup 40, including the recessed portion 13b1, and the second portion 10A2 defines the remaining portion of the retainer 10A. In addition, the second portion 10A2 defines the outer peripheral surface of the root side (i.e., the first body portion 11a side) of the second body portion 11b in the retainer 10A.

[0109] The first part 10A1 is composed of a resin portion formed by injection molding (more specifically, by so-called insert molding), and is integrally molded so as to be fixed to the metal second part 10A2. The first part 10A1 is formed by using a mold during injection molding, and a fluid resin material is flowed into a part of the space defined by the axial end of the second part 10A2 on the side not facing the cup 40 so as to fill the part of the space and solidify the fluid resin material.

[0110] The first part 10A1 is not particularly limited to being formed integrally with the second part 10A2 by insert molding. For example, the first part 10A1 may be formed as a single body and then assembled to the second part 10A2 by press-fitting or fitting.

[0111] As a raw material of the first part 10A1 formed by injection molding, it is preferable to select and use a resin material that is excellent in heat resistance, durability, corrosion resistance, etc. after curing. In this case, it is not limited to thermosetting resins represented by epoxy resins, etc., and thermoplastic resins represented by polybutylene terephthalate resins, polyethylene terephthalate resins, polyamide resins (such as nylon 6, nylon 66, etc.), propylene sulfide resins, polypropylene oxide resins, etc. can also be used.

[0112] Even in the case of such a configuration, the same effects as those described in the above embodiment can be obtained, and a gas generator having high output and high withstand pressure while being small and light can be realized.

[0113] Furthermore, in such a configuration, since a portion of the retainer 10A is formed of a resin member, it is possible to realize a gas generator that achieves a reduction in the manufacturing cost and weight of the retainer.

[0114] Furthermore, a relatively large load is applied to the portion of the holder 10A that abuts against the end-side portion of the housing 201 of the pretensioner 200, i.e., the outer peripheral surface on the root side of the second body portion 11b in the holder 10A, during caulking fixation. In the gas generator 1A according to this modification, this portion is constituted by the metal second portion 10A2. By configuring it in this way, a holder 10A can be formed that ensures the mechanical strength capable of withstanding the above-described load.

[0115] If the characteristic structures of the gas generators disclosed in the above-described embodiments and modifications are summarized, they are as follows.

[0116] [Supplementary Note 1]

[0117] A gas generator includes: a gas generant that generates gas by combustion; an igniter having an ignition portion filled with an igniting agent and a terminal pin connected to the ignition portion; a bottomed substantially cylindrical cup that houses the gas generant and has one axial end configured as an open end; and a substantially cylindrical holder that is assembled coaxially with the cup to close the open end and holds the igniter such that the ignition portion faces the gas generant. The holder has an axial end face on the side facing the cup, a first recess for receiving and holding the igniter, an axial end face on the side not facing the cup, a second recess for disposing the terminal pin and receiving and holding a connector for external connection of the igniter via the terminal pin, a partition portion that separates the first recess from the second recess by defining the bottom surface of the first recess and the bottom surface of the second recess, and an annular groove portion on the axial end face on the side facing the cup for receiving and holding the opening edge of the cup inserted axially. The bottom surface of the first recess has a stepped shape, and in a view along the axial direction of the holder, the bottom surface of the first recess has an outer annular first bottom surface and a second bottom surface that is located inside the first bottom surface and on the side of the second recess with respect to the first bottom surface. When the distance from the second bottom surface to the bottom surface of the second recess is A, the distance from the first bottom surface to the bottom surface of the second recess is B, and the distance from the bottom surface of the second recess to the annular groove portion is C, the condition A < B < C is satisfied.

[0118] [Supplementary Note 2]

[0119] As for the gas generator described in Note 1, the cup has a flange portion extending outward from the open end; an annular protrusion portion that defines the outer wall surface of the annular groove portion is provided on the axial end surface of the retainer facing the cup; the flange portion includes a second surface located on the opposite side of the first surface facing the bottom surface of the annular groove portion; the annular protrusion portion is bent inward when the flange portion is received by the annular groove portion, and the end side portion of the annular protrusion portion abuts against the second surface, thereby the flange portion is clamped in the axial direction of the cup by the end side portion of the annular protrusion portion and the bottom surface of the annular groove portion, and the cup is assembled in the retainer; the retainer also has a cylindrical first body portion and a cylindrical second body portion, and the first body portion The portion at least surrounds the above-mentioned partition portion, the end portion on the axial side of the above-mentioned partition portion of the above-mentioned retainer in the above-mentioned first recess, and the end portion on the axial side of the above-mentioned partition portion of the above-mentioned retainer in the above-mentioned second recess. The second body portion protrudes from the end portion of the above-mentioned first body portion on the axial end face side of the above-mentioned retainer that does not face the above-mentioned cup, and at least surrounds the end portion on the axial side opposite to the above-mentioned partition portion of the above-mentioned retainer in the above-mentioned second recess, and the outer shape is smaller than the above-mentioned first body portion. When the axial length of the above-mentioned second body portion is set to D, and the sum of the axial length of the above-mentioned annular protrusion portion along the axial direction of the above-mentioned first body portion and the axial length of the above-mentioned first body portion in the state after the above-mentioned cup is assembled to the above-mentioned retainer is set to E, the condition of E<1.8×D is satisfied.

[0120] [Note 3]

[0121] In the gas generator as described in Note 1 or 2, the retainer further comprises a first cylindrical body portion and a second cylindrical body portion, wherein the first body portion at least surrounds the partition portion, the end portion on the axial side of the partition portion of the retainer in the first recess, and the end portion on the axial side of the partition portion of the retainer in the second recess, and the second body portion is protruding from the end portion of the first body portion on the axial end face side of the retainer not facing the cup, and at least surrounds the end portion on the axial side opposite to the partition portion of the retainer in the second recess, and has an outer shape smaller than that of the first body portion; when the axial length of the second body portion is D and the depth of the second recess is F, the condition of F<1.8×D is satisfied.

[0122] [Note 4]

[0123] The gas generator as described in any one of Supplementary Notes 1 to 3 may include a recessed portion for fixing the short-circuit clip to the second recessed portion on the inner side surface of the second recessed portion.

[0124] [Note 5]

[0125] In the gas generator as described in Note 4, the retainer further comprises a first cylindrical body portion and a second cylindrical body portion, wherein the first body portion at least surrounds the partition portion, the end portion on the axial side of the partition portion of the retainer in the first recess, and the end portion on the axial side of the partition portion of the retainer in the second recess, and the second body portion protrudes from the end portion of the first body portion on the axial end face side of the retainer not facing the cup, surrounds at least the end portion on the axial side opposite to the partition portion of the retainer in the second recess, and has an outer shape smaller than the first body portion; at least the portion of the retainer that defines the recess is made of resin; and at least the portion of the retainer that defines the outer peripheral surface on the root side of the second body is made of metal.

[0126] (Other forms, etc.)

[0127] The shape, structure, size, number, material, etc. of each part shown in the above-mentioned embodiment of the present invention and its modified example can be variously changed as long as it does not deviate from the gist of the present invention.

[0128] Furthermore, it is needless to say that the characteristic structures shown in the above-mentioned embodiment of the present invention and its modified examples can be combined with each other within the scope not departing from the gist of the present invention.

[0129] Thus, the above-mentioned embodiment and its modification example disclosed this time are illustrative in all aspects and are not restrictive. The technical scope of the present invention is defined by the claims, and all changes within the meaning and scope equivalent to the description of the claims are included.

[0130] Description of Reference Numerals

[0131] 1, 1A, 1X1, 1X2 gas generator; 10, 10A retainer; 10A1 first part; 10A2 second part; 11 body; 11a first body; 11b second body; 12 first recess; 12a bottom surface; 12a1 first bottom surface; 12a2 second bottom surface; 12b inner side surface; 13 second recess; 13a bottom surface; 13b inner side surface; 13b1 recessed portion; 14 partition; 14a opening; 15 locking portion; 16 annular groove ; 16a bottom surface; 16c inner wall surface; 17 annular flange portion; 20 igniter; 21 base; 22 ignition portion; 23 terminal pin; 30 sealing component; 40 cup; 41 side wall portion; 41a open end; 42 bottom wall portion; 42a notch; 43 flange portion; 43a first surface; 43b second surface; 44 accommodation space; 50 gas generating agent; 100 short-circuit clamp; 101 claw portion; 102 leaf spring portion; 200, 200A pretensioner; 201, 201A shell.

Claims

1. A gas generator, characterized in that, it comprises: a gas generant that generates gas by combustion; an igniter having an ignition part filled with an igniting powder and a terminal pin connected to the ignition part; a bottomed substantially cylindrical cup that houses the aforementioned gas generant and has one axial end configured as an open end; and a substantially cylindrical retainer that is coaxially assembled by the aforementioned cup to close the aforementioned open end and holds the aforementioned igniter with the aforementioned ignition part facing the aforementioned gas generant; the aforementioned retainer has: a first recess provided on the axial end face on the side facing the aforementioned cup to receive and hold the aforementioned igniter; a second recess provided on the axial end face on the side not facing the aforementioned cup to configure the aforementioned terminal pin and receive and hold a connector for external connection of the aforementioned igniter via the terminal pin; a partition part that separates the aforementioned first recess from the aforementioned second recess by defining the bottom surfaces of the aforementioned first recess and the aforementioned second recess; and an annular groove part provided on the axial end face on the side facing the aforementioned cup to receive and hold the opening edge of the aforementioned cup inserted along the axis; the bottom surface of the aforementioned first recess has a stepped shape, and in a view along the axis of the aforementioned retainer, the bottom surface of the first recess has an outer annular first bottom surface and a second bottom surface located inside the first bottom surface and on the side of the aforementioned second recess with respect to the first bottom surface; when the distance from the aforementioned second bottom surface to the bottom surface of the aforementioned second recess is A, the distance from the aforementioned first bottom surface to the bottom surface of the aforementioned second recess is B, and the distance from the bottom surface of the aforementioned second recess to the aforementioned annular groove part is C, the condition A < B < C is satisfied.

2. The gas generator according to claim 1, characterized in that, the aforementioned cup has a flange part extending outward from the aforementioned open end; on the axial end face of the aforementioned retainer on the side facing the aforementioned cup, an annular protruding edge part that defines the outer wall surface of the aforementioned annular groove part is provided; the aforementioned flange part includes a second surface located on the side opposite to a first surface opposed to the bottom surface of the aforementioned annular groove part; by bending the aforementioned annular protruding edge part inward in a state where the aforementioned flange part is received in the aforementioned annular groove part, a part of the end side of the aforementioned annular protruding edge part abuts against the aforementioned second surface, whereby the aforementioned flange part is clamped in the axial direction of the aforementioned cup by the part of the end side of the aforementioned annular protruding edge part and the bottom surface of the aforementioned annular groove part, and the aforementioned cup is assembled to the aforementioned retainer; the aforementioned retainer further has a cylindrical first body part and a cylindrical second body part. The first body part surrounds at least the partition part, the end part of the aforementioned first recess on the partition part side in the axial direction of the aforementioned retainer, and the end part of the aforementioned second recess on the partition part side in the axial direction of the aforementioned retainer. The second body part protrudes from the end part of the first body part on the side of the axial end face of the aforementioned retainer not facing the aforementioned cup and surrounds at least the end part of the aforementioned second recess on the side opposite to the partition part side in the axial direction of the aforementioned retainer, and has an outer shape smaller than that of the aforementioned first body part; When the axial length of the second body portion is D and the sum of the axial length of the annular protrusion portion along the axial direction of the first body portion and the axial length of the first body portion after the cup is assembled to the retainer is E, the condition E<1.8×D is satisfied.

3. The gas generator according to claim 1, It is characterized in that The retainer further comprises a first cylindrical body portion and a second cylindrical body portion, the first body portion at least surrounding the partition portion, an end portion of the retainer in the first recess on the partition portion side in the axial direction, and an end portion of the retainer in the second recess on the partition portion side in the axial direction, the second body portion is provided so as to protrude from an end portion of the first body portion located on the axial end surface side of the retainer not facing the cup, surrounds at least an end portion of the retainer in the second recess on the axial direction opposite to the partition portion side, and has an outer shape smaller than that of the first body portion; When the axial length of the second body portion is denoted by D and the depth of the second recess is denoted by F, the condition of F<1.8×D is satisfied.

4. The gas generator according to claim 1, It is characterized in that A recessed portion for fixing the short-circuit clip to the second recessed portion is provided on the inner side surface of the second recessed portion.

5. The gas generator according to claim 4, It is characterized in that The retainer further comprises a first cylindrical body portion and a second cylindrical body portion, the first body portion at least surrounding the partition portion, an end portion of the retainer in the first recess on the partition portion side in the axial direction, and an end portion of the retainer in the second recess on the partition portion side in the axial direction, the second body portion is provided so as to protrude from an end portion of the first body portion located on the axial end surface side of the retainer not facing the cup, surrounds at least an end portion of the retainer in the second recess on the axial direction opposite to the partition portion side, and has an outer shape smaller than that of the first body portion; At least a portion of the retainer defining the recessed portion is made of resin; At least a portion of the retainer that defines an outer peripheral surface on a root side of the second body portion is made of metal.

Images