Actuator for airbag system

Abstract

To provide an actuator for airbag systems capable of ensuring excellent airtightness, and being immediately uncoupled from a coupling member, which extends from an airbag, at a time of activation.SOLUTION: An actuator A is coupled to coupling means 27 which is attached to the side of a storage region 11 and extends from an airbag 20. The actuator includes a retention part 45 that retains a squib 37, a cap part 55 that is disposed on the other end of the retention part and is thus opposed to the squib. The retention part includes a cylindrical part 47 which encloses the whole circumference of the flank of at least the proximal part of the squib. The cap part includes a ceiling part 56 which is opposed to the squib, and a circumferential wall part 58 that shields the internal surface of the cylindrical part in the form of a cylinder extending from the margin of the ceiling part. When the ceiling part of the cap part receives a pressure of a combustion gas G generated when the squib is activated, the circumferential wall part is separated from the cylindrical part and the ceiling part is moved. Thus, the actuator can be uncoupled from the coupling means.SELECTED DRAWING: Figure 13

Description

Technical Field

[0001] The present invention relates to an actuator for an airbag device for controlling the inflated state of an airbag. Background Art

[0002] Conventionally, in an airbag device, as an actuator used for controlling the inflated state of an airbag, there has been known a configuration in which a cap portion arranged to face a squib is attached to a holding portion that holds the squib on one end side and has an opening on the other end side. In this actuator, the cap portion has a flat ceiling portion and two leg portions extending from the ceiling portion, and is attached to the other end side of the holding portion by engaging a locking projection provided on the distal end side of the leg portion with a locking recess provided on the holding portion side (see, for example, Patent Document 1). In this actuator, the distal end side of a connecting member extending from the airbag is inserted into a region between the ceiling portion of the cap portion and the holding portion, so that the connecting member is connected. The connection with the connecting means is released by pressing the ceiling portion with the pressure of combustion gas generated when the squib is activated to release the engagement between the locking recess and the locking projection. Prior Art Literature Patent Literature

[0003] Patent Document 1 Japanese Unexamined Patent Application Publication No. 2023-90502 Summary of the Invention Problem to be Solved by the Invention

[0004] However, in conventional actuators, the connecting member is connected by inserting the portion between the top portion of the cap and the holding portion into the connecting member, meaning that a gap for inserting the connecting member is formed between the top portion of the cap and the tip of the holding portion. Furthermore, in conventional actuators, the cap is connected to the holding portion using two legs extending from the top portion, and the holding portion is not configured to be closed off by the cap portion. Therefore, in terms of rapidly pressing the top portion with the pressure of the combustion gas generated from the squib during operation, there was room for improvement in improving the airtightness when the cap portion is attached to the holding portion (vehicle mounted state).

[0005] The present invention aims to solve the above-mentioned problems and to provide an actuator for an airbag system that can ensure good airtightness and quickly release the connection with the connecting member extending from the airbag during operation. [Means for solving the problem]

[0006] The actuator for an airbag system according to the present invention is attached to the storage area side where the folded airbag is stored, and is configured to control the inflation state of the airbag by connecting a connecting means extending from the airbag and maintaining or releasing the connection state with the connecting means. An actuator for an airbag device comprising a squib, a holding portion that holds the squib at one end, and a cap portion disposed on the other end of the holding portion so as to face the squib, The retaining portion holds the squib at one end and includes a cylindrical portion that can cover the entire circumference of the side of at least the base of the squib. The cap part, The ceiling section is positioned opposite the squib, A peripheral wall portion is arranged to cover the inner or outer circumference of the cylindrical portion, as a cylindrical shape extending from the periphery of the ceiling portion. It is configured to include such a feature that closes the other end of the holding part, The cap portion is attached to the holding portion by locking the peripheral wall portion to the cylindrical portion, and is characterized in that, when attached to the holding portion, the state in which the cylindrical portion or peripheral wall portion is inserted into the insertion hole formed on the tip side of the connecting means can be maintained, and when the ceiling portion receives the pressure of the combustion gas generated when the squib is operating, the connection with the connecting means can be released by moving the ceiling portion while detaching the peripheral wall portion from the cylindrical portion.

[0007] In the airbag actuator of the present invention, the cap portion is attached to the holding portion such that the cylindrical peripheral wall portion extending from the periphery of the ceiling portion is positioned on the inner or outer circumference side of the cylindrical portion that covers at least the entire side of the base portion of the squib in the holding portion. That is, in the airbag actuator of the present invention, with the cap portion attached to the holding portion, the area around the squib is covered almost without gaps by the ceiling portion and the peripheral wall portion or the cylindrical portion of the holding portion. Therefore, the airtightness is good, and when the squib is activated, the combustion gas generated can quickly press against the ceiling portion, making it possible to quickly release the connection with the connecting means extending from the airbag.

[0008] Therefore, the actuator for the airbag system of the present invention ensures good airtightness and allows for quick release of the connection with the connecting member extending from the airbag during operation.

[0009] Furthermore, in the airbag actuator of the present invention, the cap portion is configured to move the ceiling portion while detaching the peripheral wall portion from the cylindrical portion when the pressure of the combustion gas is received by the ceiling portion. In other words, in the airbag actuator of the present invention, the cap portion is configured to detach from the holding portion without damaging the peripheral wall portion. Therefore, compared to the cap portion of a conventional actuator configured to have two legs extending from the ceiling portion, the cap portion does not have a locally large protruding part, and damage when it detaches from the holding portion and scatters can be suppressed.

[0010] Furthermore, in the airbag device actuator of the present invention, if the peripheral wall portion is positioned on the inner circumference side of the cylindrical portion and the tip portion covers the side of the squib without any gaps, the side of the squib is covered without any gaps by the peripheral wall portion extending from the ceiling portion. This makes it possible to quickly direct the combustion gas generated when the squib is operated towards the ceiling portion instead of towards the side of the squib, which is preferable.

[0011] Furthermore, in the actuator for the airbag device with the above configuration, if the cap portion is configured such that the inner circumferential surface from the peripheral wall portion to the ceiling portion is curved in a hemispherical shape, it becomes possible to apply pressure substantially uniformly to this hemispherical curved region when the ceiling portion is pressed by the combustion gas, which is preferable. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram showing a steering wheel airbag system using an actuator, which is one embodiment of the present invention. [Figure 2] Figure 1 is a longitudinal cross-sectional view of the steering wheel airbag system. [Figure 3] Figure 1 is a partially enlarged bottom view showing the inflator and the actuator of the embodiment in the steering wheel airbag device. [Figure 4] Figure 1 is a schematic diagram showing the airbag used in the airbag system and the area around the exhaust port in the airbag. [Figure 5] Figure 3 is a partially enlarged bottom view showing the actuator. [Figure 6] This is a schematic perspective view showing the actuator of the embodiment, with views from the cap side and views from the holding side. [Figure 7] This is a schematic exploded perspective view showing the cap portion and the holding portion of the actuator according to the embodiment. [Figure 8] This is a longitudinal cross-sectional view of the actuator of the embodiment, along the left-right direction. [Figure 9]It is a vertical cross-sectional view taken along the front-rear direction of the actuator in FIG. 8, showing the base side portion of the peripheral wall portion in the cap portion. [Figure 10] In the actuator according to the embodiment, it is a vertical cross-sectional view showing a state where a cap portion and a holding portion holding a squib are arranged. [Figure 11] In the actuator according to the embodiment, it is a partially enlarged vertical cross-sectional view showing a portion of the locking projection and the locking recess. [Figure 12] In the actuator according to the embodiment, it is a partially enlarged cross-sectional view showing the locking projection provided on the cap portion and the locking recess provided on the holding portion. [Figure 13] It is a vertical cross-sectional view showing the actuator according to the embodiment before and after actuation. MODE FOR CARRYING OUT THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the embodiment, an actuator A used in an airbag device M mounted on a steering wheel W will be described as an example. As shown in FIGS. 1 and 2, the steering wheel W includes a steering wheel main body 1 and an airbag device M arranged above a central boss portion B of the steering wheel main body 1. In the embodiment, the steering wheel main body 1 includes a ring portion R that is gripped during steering, a boss portion B arranged substantially at the center of the ring portion R and connected to a steering shaft SS, and a predetermined number of spoke portions (not shown) connecting the boss portion B and the ring portion R.

[0014] In the embodiment, unless otherwise specified, the front-rear, up-down, and left-right directions are based on the straight-ahead steering of the steering wheel W mounted on a vehicle. The up-down direction is defined as the direction along the axial direction of the steering shaft SS (see FIG. 2) to which the steering wheel W is assembled, the front-rear direction is defined as the front-rear direction of the vehicle which is the direction orthogonal to the axis of the steering shaft SS, and the left-right direction is defined as the left-right direction of the vehicle which is the direction orthogonal to the axis of the steering shaft SS.

[0015] As shown in FIGS. 1 and 2, a steering wheel body 1 includes: a core bar 2 arranged to connect respective parts of a ring portion R and a boss portion B and made of metal such as aluminum alloy; a covering layer 3 made of synthetic resin that covers the core bar 2 at the ring portion R and a spoke portion (not shown); and a lower cover 4 made of synthetic resin that covers the lower part of the boss portion B.

[0016] As shown in FIG. 2, an airbag apparatus M includes: an airbag 20; an inflator 9 that supplies inflation gas to the airbag 20; a case 11 serving as an accommodation portion that accommodates and holds the folded airbag 20 and the inflator 9; an airbag cover 15 that covers the folded airbag 20; and a retainer 7 for attaching the airbag 20 and the inflator 9 to the case 11.

[0017] As shown in FIG. 2, the inflator 9 includes: a substantially cylindrical main body portion 9a having a plurality of gas discharge ports 9b; and a flange portion 9c for attaching the inflator 9 to the case 11. The flange portion 9c is formed with through holes (not shown) for allowing respective bolts 7a of the retainer 7 to pass therethrough. The inflator 9 is electrically connected to a control device 90 described later.

[0018] In the embodiment, the operation of the inflator 9 of the airbag apparatus M and a squib 37 of an actuator A described later is configured to be controlled by the control device 90 shown in FIG. 1.

[0019] As shown in Figure 1, the control device 90 is electrically connected to an occupant detection sensor capable of detecting the physique and seating position of the driver MD as an occupant seated in the driver's seat DS, such as a position detection sensor 92 capable of detecting the distance between the steering wheel W and the driver MD, and a weight detection sensor 93 capable of detecting the weight of the driver MD. It is also electrically connected to a collision detection sensor 94 capable of detecting the acceleration and direction of acceleration of the vehicle. The control device 90 receives electrical signals from these position detection sensors 92, weight detection sensors 93, or collision detection sensors 94 to activate the inflator 9 of the airbag device M and the squib 37 of actuator A. In this embodiment, the operation of the squib 37 of actuator A is controlled by the control device 90 so as to control the rise in internal pressure of the airbag 20 when the airbag 20 inflates during the operation of the inflator 9. Specifically, the squib 37 of actuator A is controlled to inflate the airbag 20 in a suitable inflation mode by exhausting the inflation gas that has flowed into the airbag 20 to the outside of the airbag 20.

[0020] The case 11, which serves as the storage area, is made of sheet metal and, as shown in Figure 2, comprises a roughly rectangular plate-shaped bottom wall portion 12 into which the inflator 9 is inserted and mounted from below, and a peripheral wall portion 13 extending vertically from the outer edge of the bottom wall portion 12. In the area in front of the opening (not shown in the figure) for inserting the main body portion 9a of the inflator 9, there is an insertion hole 12a for inserting a connecting string portion 27, which will be described later as a connecting means extending from the airbag 20, a mounting hole 12b for mounting a mounting bracket portion 75 of the actuator A (described later), and a through hole 12c for passing a protruding piece 79 formed on the mounting bracket portion 75 (see B, 8, and 9 in Figures 3, 5, and 6). An outwardly extending mounting piece (not shown) is formed on the upper end side of the peripheral wall portion 13. In this embodiment, the airbag device M is mounted on the upper part of the boss portion B of the steering wheel body 1, which is already attached to the steering shaft SS, by using a mounting base plate of a horn switch mechanism attached to a mounting piece (not shown) to attach and fix the case 11 to the core metal 2 of the steering wheel W. The side wall portion 15c of the airbag cover 15 is attached to the peripheral wall portion 13 of the case 11 using rivets 16 or the like (see Figure 2). In this embodiment, the airbag 20 and the inflator 9 are attached to the bottom wall portion 12 of the case 11 by using the bolt 7a (see Figure 3) of the retainer 7 located inside the airbag 20 as the mounting means. The bolt 7a is passed through the periphery of the intake opening 21 in the airbag 20 (described later), the bottom wall portion 12 of the case 11, and the flange portion 9c of the inflator 9, and secured with a nut 8, although detailed illustration is omitted.

[0021] The airbag cover 15 is made of synthetic resin and includes a ceiling wall portion 15a that covers the top of the airbag 20 housed in the case 11, and a roughly rectangular cylindrical side wall portion 15c that extends downward from near the outer edge of the ceiling wall portion 15a (see Figure 2). The ceiling wall portion 15a has two door portions 15b, 15b that open forward and backward when pushed by the inflating airbag 20.

[0022] The airbag 20 is a bag-shaped structure made of a flexible woven fabric consisting of polyamide yarn, polyester yarn, etc., and inflates to cover the upper surface of the steering wheel W by allowing inflation gas to flow into it, as shown by the dashed line in Figure 1. The airbag 20 has an intake opening 21, as shown in Figure 4A. This intake opening 21 is for inserting the main body 9a of the inflator 9 from below, and mounting holes 22 for inserting the bolts 7a of the retainer 7 are formed around the periphery of the intake opening 21. In addition, a circular exhaust hole 24 is formed in front of the intake opening 21 of the airbag 20, and insertion holes 23A and 23B are formed between the exhaust hole 24 and the intake opening 21 at two locations: near the rear edge of the exhaust hole 24 and near the front edge of the intake opening 21, through which a connecting string portion 27, which serves as a connecting means, can be inserted (see Figure 4A). Each of the insertion holes 23A and 23B is formed in a slit shape that is substantially aligned in the left-right direction, allowing the connecting cord portion 27 to be inserted through it.

[0023] A flap 26 is provided on the outer periphery of the airbag 20 to cover the exhaust port 24. The flap 26, like the airbag 20, is made of a flexible woven fabric such as polyester yarn or polyamide yarn, and its outer shape is roughly rectangular so as to cover the exhaust port 24. One side (the front side) that is away from the intake opening 21 is connected to the front edge of the exhaust port 24, and the base portion 27a of a connecting cord portion 27, which will be connected to the actuator body 35 described later, is connected to the side facing the intake opening 21 (the rear side). This connecting cord portion 27 is made of a flexible, narrow strip and is positioned roughly along the front-to-back direction when the airbag 20 is laid flat. A loop portion 28 is formed at the tip 27b side of the connecting cord portion 27, which allows the peripheral wall portion 58 (specifically, the base portion 59) of the cap portion 55 of the actuator body 35, described later, to be inserted. In other words, in this embodiment, this loop portion 28 constitutes an insertion hole through which the base portion 59 of the cap portion 55 can be inserted. The external shape (internal diameter) of this loop portion 28 is set to allow the base portion 59 of the cap portion 55 to be inserted, but prevents the ceiling portion 56 of the cap portion 55, described later, from being inserted. The length of the connecting cord portion 27 is set to allow the airbag 20 to be inflated without hindrance even when the connection state with the actuator body 35 at the tip 27b side is maintained. The connecting cord portion 27 is inserted into the insertion holes 23A and 23B formed in the airbag 20, with the base portion 27a and tip portion 27b positioned on the outer circumference of the airbag 20 and the intermediate portion positioned on the inner circumference of the airbag 20, with the flap 26 covering the outer circumference of the exhaust hole 24. While maintaining this state, it is folded together with the airbag 20 and stored inside the case 11. When mounted in the vehicle, the tip portion 27b of the connecting cord portion 27 protrudes from the insertion hole 12a of the case 11 and is connected to the actuator body 35 by inserting the peripheral wall portion 58 (base portion 59) of the cap portion 55 of the actuator body 35 into the loop portion 28 (see A in Figures 5-7, 8).

[0024] In this embodiment, the airbag 20 inflates in two inflation modes: an open mode in which the exhaust port 24 is opened, and a closed mode in which the exhaust port 24 remains closed. Specifically, when the actuator body 35 is not operating and the connection between the tip 27b of the connecting string portion 27 and the actuator body 35 is maintained (the state in which the base portion 59 of the cap portion 55 is inserted into the loop portion 28, see Figure 13A), the tip of the flap 26 is pressed down by the base portion 27a of the connecting string portion 27, and the airbag 20 inflates in a closed mode in which the flap 26 blocks the exhaust port 24, as shown in Figure 4B. When the actuator body 35 is activated, the cap portion 55 detaches from the retaining portion 45 (described later) that constitutes the actuator body 35, and the peripheral wall portion 58 of the cap portion 55 detaches from the loop portion 28, releasing the connection between the connecting string portion 27 and the actuator body 35 (see Figure 13B). In this state, the flap 26 is pushed by the expansion gas attempting to escape from the exhaust port 24, causing the flap 26 to open. As shown in Figure 4C, the airbag 20 inflates in the open mode with the exhaust port 24 open. The airbag 20 completes its inflation while maintaining its internal pressure in the closed mode and suppressing the rise in internal pressure in the open mode. The operation of the actuator body 35 is controlled by the control device 90. In this embodiment, when the control device 90 detects excessive proximity of the driver MD to the steering wheel W based on a signal from the position detection sensor 92, or detects that the driver MD is small in stature based on a signal from the weight detection sensor 93, it activates the actuator body 35 to reduce the internal pressure of the airbag 20 when it inflates, either simultaneously with or slightly after the operation of the inflator 9.

[0025] In this embodiment, actuator A is positioned in the front region of the inflator 9, as shown in Figures 2 and 3. Actuator A comprises an actuator body 35 and a mounting bracket portion 75 for attaching the actuator body 35 to the case 11, which serves as a housing.

[0026] As shown in Figures 6A and 6B, the actuator body 35 has a roughly cylindrical shape, and in this embodiment, it is attached to the case 11 using a mounting bracket 75 with its axial direction roughly aligned with the left-right direction. As shown in Figure 8, the actuator body 35 includes a holding portion 45, a squib 37 held at the base end (left end 45b in this embodiment) of the holding portion 45, and a cap portion 55 disposed at the other end (tip end, right end 45a in this embodiment) of the holding portion 45, opposite the squib 37. The holding portion 45 and the cap portion 55 are made of synthetic resin such as polyamide resin mixed with reinforcing filler.

[0027] As shown in Figure 8, the squib 37 comprises a main body 38 and a pair of conductive pins 40, 40 extending to the left from the main body 38. The conductive pins 40 are positioned so that their tips are exposed from the left side of the base 46 of the holding portion 45, which will be described later, and are the part to which a connector (not shown) electrically connected to the control device 90 is connected. The main body 38, although not shown in detail, is configured to house a gas generating agent capable of generating combustion gas, and the outer circumference of this gas generating agent is covered by a thin metal cover 39 made of aluminum alloy or the like. The main body 38 operates when an operating signal is input from the control device 90, and burns the gas generating agent. At this time, the cover 39 covering the outer circumference of the gas generating agent is broken starting near the center of the region covering the cap portion 55 side of the gas generating agent (the region on the right end face 38a side of the main body portion 38, and the region of the disc-shaped top plate portion 39a), and is divided into multiple parts, opening radially (see the dashed line in Figure 8). The squib 37 is integrally molded with the holding portion 45 by insert molding during the formation of the holding portion 45, and is held by the holding portion 45.

[0028] As shown in Figures 8 and 10, the holding portion 45 includes a base portion 46 disposed on the base side (left end 45b side) to hold the squib 37 (more specifically, the area from the left end face side of the main body portion 38 to the base side of the conductive pin 40), and a cylindrical portion 47 extending from the base portion 46 and capable of covering at least the entire circumference of the side of the squib 37 (more specifically, the main body portion 38) on the base side. Furthermore, on the outer circumferential surface side of the holding portion 45, a projection 45c for positioning relative to the mounting bracket portion 75 is formed, protruding in a substantially rectangular shape at a position slightly to the left of the left-right center. As described above, the conductive pin 40 in the squib 37 is arranged so that its tip portion protrudes to the left from the left end face side of the base portion 46. The cylindrical portion 47 is substantially cylindrical and, as shown in Figure 10, is configured to provide a gap between it and the side surface 38b of the main body portion 38, with the tip side (right end side) being open. In this embodiment, the cylindrical portion 47 is configured such that its tip (right end 47c) is positioned slightly forward of the right end surface 38a of the main body portion 38 of the squib 37, and covers the entire side of the main body portion 38. A locking recess 48 is formed on the inner circumferential surface 47a side of the cylindrical portion 47 for engaging a locking projection 66 formed on the peripheral wall portion 58 of the cap portion 55, which will be described later. The locking recess 48 is formed to recess the inner circumferential surface 47a near the tip (right end 47c) of the cylindrical portion 47, and in this embodiment, as shown in Figures 7 and 10B, it is arranged to be continuously recessed around the entire circumference of the cylindrical portion 47. More specifically, as shown in Figure 12, the locking recess 48 is formed by recessing the inner circumferential surface 47a of the cylindrical portion 47 in a roughly "V" shape in cross-section, with two inclined surfaces 48a, 48a arranged side by side on the left and right sides (with the tip 48b of the outermost recess located near the center on the left and right sides). The amount of recess L1 of the locking recess 48 is set to about 1 / 8 of the thickness dimension T1 of the cylindrical portion 47, and the width dimension L2 is set to about 6 times the amount of recess L1, which is about 2 / 3 of the thickness dimension T1 of the cylindrical portion 47 (see Figure 12). The inclined surface 48a has an inclination angle α (see Figure 12) of about 20° relative to the inner circumferential surface 47a of the cylindrical portion 47.Furthermore, in this embodiment, the tip surface 50 formed on the tip (right end 47c) side of the cylindrical portion 47 is formed to be inclined with respect to the axial direction of the holding portion 45 (coinciding with the inner circumferential surface 47a) such that, in a cross section substantially along the front-rear direction, the inner circumferential surface 47a side is positioned as far to the right. Specifically, the tip surface 50 has an inclination angle β (see Figure 12) with respect to the axial direction (inner circumferential surface 47a) set to approximately 60°. In this embodiment, the tip surface 50 is configured such that the outer edge 50a on the outer circumferential surface 47b side is positioned slightly to the right of the tip 48b of the recess in the locking recess 48, and is positioned to be substantially coincidental with the right end surface 38a of the main body portion 38 of the squib 37 (see Figures 11 and 12). That is, the locking recess 48 is formed such that the tip 48b of the recess is positioned slightly to the left of the right end surface 38a of the main body portion 38.

[0029] As shown in Figures 8 and 10, A, the cap portion 55 comprises a ceiling portion 56 positioned opposite the squib 37 and a cylindrical peripheral wall portion 58 extending from the periphery of the ceiling portion 56. The ceiling portion 56 has an outer shape that is approximately disc-shaped. In this embodiment, the outer diameter dimension D2 of the ceiling portion 56 is set to be approximately the same as the outer diameter dimension of the holding portion 45 (i.e., the outer diameter dimension D1 of the cylindrical portion 47) (see Figures 10, A and B).

[0030] As shown in Figure 10A, the peripheral wall portion 58 has an outer shape that is roughly cylindrical with an opening on the left end side facing the squib 37. It comprises a base portion 59 located on the ceiling portion 56 side and a tip portion 63 positioned on the squib 37 side, with an outer diameter slightly smaller than that of the base portion 59. The peripheral wall portion 58 has a step portion 61 on the outer circumferential surface 58b side, with the inner circumferential surface 58a side being flush, so that the tip portion 63 has a smaller diameter than the base portion 59. In other words, the base portion 59 is constructed to be slightly thicker than the tip portion 63. In this embodiment, the tip portion 63 is configured to cover the inner circumference of the cylindrical portion 47 in the holding portion 45. The tip portion 63 has an outer diameter D3 that is approximately the same as the inner diameter d1 of the cylindrical portion 47, and a thickness T2 that is equivalent to the opening width H of the gap between the cylindrical portion 47 and the main body portion 38 of the squib 37, so that it can be inserted into the gap between the cylindrical portion 47 and the main body portion 38 (see Figures 10A, B and 12). When the cap portion 55 is attached to the holding portion 45, the tip portion 63, which is the tip-side region of the peripheral wall portion 58, is configured to cover the side surface 38b of the main body portion 38 of the squib 37 without any gaps (see Figure 13A). Although a small gap is shown between the side surface 38b of the main body portion 38 and the tip portion 63 in Figures 6 and 11, this gap is actually very small in reality. In this specification, "without gaps" includes even slight gaps that occur between the side surface 38b of the main body 38 and the tip portion 63 due to manufacturing errors. In the embodiment, when the cap portion 55 is attached to the holding portion 45 (when the locking projection 66 is locked into the locking recess 48), the tip surface (left end surface 63b) of the tip portion 63 is positioned with a slight gap between it and the base portion 46 of the holding portion 45 (see Figure 11).

[0031] A locking projection 66 is formed on the outer circumferential surface 63a side of the tip end portion 63 of the peripheral wall portion 58, which is inserted into and locked into a locking recess 48 formed on the inner circumferential surface 47a side of the cylindrical portion 47 of the holding portion 45. The locking projection 66 is formed to protrude outward from the outer circumferential surface 63a at approximately the center on the left and right sides of the tip end portion 63, and in this embodiment, as shown in Figure 7, it is arranged to protrude continuously around the entire circumference of the tip end portion 63. The cross-sectional shape of the locking projection 66 on the side approximately aligned with the left and right direction is formed to be a flat, approximately trapezoidal shape, with a width dimension L4 set to be approximately the same as the width dimension L2 of the locking recess 48, and a protrusion amount L3 set to about half the recess amount L1 of the locking recess 48 (see Figure 12). Furthermore, the protrusion amount L3 of this locking projection 66 is set to about 1 / 10 of the thickness dimension T2 of the tip end portion 63. The locking projection 66 is configured to have inclined surfaces 66a, 66a on its right and left ends. These inclined surfaces 66a are positioned in accordance with the inclined surface 48a formed in the locking recess 48, and the inclination angle γ (see Figure 12) of the tip portion 63 with respect to the outer circumferential surface 63a is set to approximately 20°. The external shape of the locking projection 66 (the amount of outward protrusion, the angle of the inclined surface 66a, the amount of protrusion relative to the thickness dimension T2 of the tip portion 63, and the dimensional difference relative to the recess amount L1 of the locking recess 48) is designed to suppress damage to the tip portion 63 and the cylindrical portion 47 of the holding portion 45 when the actuator body 35 is activated and the locking is released from the locking recess 48, thereby allowing the tip portion 63 to be detached from the cylindrical portion 47 (the cap portion 55 from the holding portion 45).

[0032] The base portion 59 of the peripheral wall portion 58 has an outer diameter dimension D4 set to approximately 4 / 5 of the outer diameter dimension D2 of the ceiling portion 56 (see A in Figure 10). This base portion 59 is the part that is exposed and positioned between the holding portion 45 and the ceiling portion 56 when the cap portion 55 is attached to the holding portion 45 (see Figure 11). In this embodiment, as shown in Figures 8 and 9, this base portion 59 is inserted into a loop portion 28 formed on the tip 27b side of the connecting string portion 27, which serves as a connecting means in the airbag 20.

[0033] Furthermore, in this embodiment, the cap portion 55 is constructed with the inner circumferential surface 55a side, extending from the peripheral wall portion 58 to the ceiling portion 56, curved in a hemispherical shape. More specifically, in this embodiment, the cap portion 55 has a curved surface portion 70 that curves in a hemispherical shape on the inner circumferential surface 55a side, extending from the base portion 59 to the ceiling portion 56 (see Figure 10A). In this embodiment, the inner diameter dimension d2 of this curved surface portion 70 is set to be approximately the same as the outer diameter dimension D5 of the main body portion 38 of the squib 37 (see Figures 10A and B). In addition, the curved surface portion 70 is configured such that the separation distance L5 (see Figure 8) between the center of the curved surface portion 70 and the main body portion 38 when the cap portion 55 is attached to the holding portion 45 is set to be slightly larger than the radius dimension of the main body portion 38 (i.e., 1 / 2 of the outer diameter dimension D5).

[0034] The mounting bracket portion 75 is made of sheet metal and, as shown in Figures 5 and 6, A and B, comprises a main body portion 76 that wraps around the outer circumference of the holding portion 45 over almost its entire circumference, and mounting portions 77 that are positioned on both ends of the main body portion 76 and bolted to the bottom wall portion 12 of the case 11 in a double-layered configuration. The mounting portions 77 have through holes 77a through which bolts 82 can be inserted. In the main body portion 76, in the area covering the lower surface of the holding portion 45, through holes 78 are formed, opening in a roughly rectangular shape, through which projections 45c formed on the holding portion 45 can pass. Also, in the front end area on the right edge 76b side of the main body portion 76, a protruding piece 79 is formed so as to protrude upward toward the bottom wall portion 12 of the case 11. This protruding piece 79 is inserted through a through hole 12c formed in the bottom wall portion 12 and is provided for positioning when attaching the actuator body 35 to the bottom wall portion 12 using the mounting bracket portion 75. Furthermore, two restricting pieces 80, 80 are formed on both the left and right ends of the right edge 76a side of the main body portion 76, extending forward. These restricting pieces 80 are arranged to cover the front and rear sides of the base portion 59 of the cap portion 55, extending to the vicinity of the ceiling portion 56 (see Figures 5 and 9), and are provided to prevent the tip 27b side (loop portion 28) of the connecting string portion 27 from coming out of the actuator body 35 when mounted on a vehicle.

[0035] Next, the mounting of the actuator A and airbag device M of the embodiment onto a vehicle will be described. First, with the retainer 7 placed inside the airbag 20, the exhaust port 24 is kept closed by the flap 26, the connecting string portion 27 is inserted into the insertion holes 23A and 23B, and the tip 27b is kept protruding from the insertion hole 23B, and the airbag 20 is folded so that it can be stored inside the case 11. After that, the folded airbag 20 is stored in the case 11. At this time, the tip 27b of the connecting string portion 27 protrudes from the insertion hole 12a of the bottom wall portion 12. The base portion 59 of the cap portion 55 of the actuator body 35 is inserted through the loop portion 28 formed on the tip 27b of the connecting string portion 27. Next, the cap portion 55, which is passing through the tip 27b (loop portion 28) of the connecting string portion 27, is attached to the holding portion 45 with the mounting bracket portion 75 attached, thereby forming the actuator body 35. By attaching the mounting bracket portion 77 to the bottom wall portion 12 using bolts 82 and nuts 83, the actuator body 35 can be connected to the connecting string portion 27, which serves as a connecting member, and at the same time, the actuator A can be attached to the case 11. Next, the main body portion 9a of the inflator 9 is inserted from below, and the inflator 9 and airbag 20 are attached to the case 11 using the bolts 7a and nuts 8 of the retainer 7 that protrude from the bottom wall portion 12. Furthermore, the airbag cover 15 is placed over the case 11, and the airbag cover 15 is attached to the case 11 using rivets 16, etc. After that, the horn switch mechanism (not shown) is assembled to a mounting piece (not shown) of the case 11, thereby completing the airbag device M. This airbag device M can be attached to the steering wheel body 1, which has been pre-fastened to the steering shaft SS, using a mounting base plate (not shown) of the horn switch mechanism. Subsequently, by connecting a connector (not shown) to which lead wires extending from the control device 90 are connected to the squib 37 of the actuator body 35, and by also connecting lead wires (not shown) extending from the control device 90 to the inflator 9, the airbag device M and actuator A can be mounted on the vehicle.

[0036] In the airbag device M of this embodiment, when inflation gas is discharged from the gas outlet 9b of the inflator 9, the airbag 20 inflates by allowing the inflation gas to flow into its interior, pushing open the door portions 15b, 15b of the airbag cover 15, and protruding from the case 11, completing the inflation so as to cover substantially the entire upper surface of the steering wheel W, as shown by the dashed line in Figure 1. At this time, in the actuator body 35 of the actuator A, when the squib 37 is activated in response to an operation signal from the control device 90, the combustion gas G generated by the operation of the squib 37 is ejected toward the cap portion 55, breaking open the cover 39 that covers the outer circumference of the main body portion 38, and the combustion gas G presses against the ceiling portion 56 of the cap portion 55. The cap portion 55 receives the pressure of the combustion gas G from the top portion 56, releasing the locking state with the locking recess 48 of the locking projection 66, and the peripheral wall portion 58 detaches from the cylindrical portion 47, thus detaching from the holding portion 45. As shown in Figure 13B, it then detaches from the loop portion 28 provided on the tip 27b side of the connecting string portion 27, releasing the connection with the connecting string portion 27. Then, as shown in Figure 4C, the flap 26 that was connected to the connecting string portion 27 opens the exhaust port 24 of the airbag 20, and the expansion gas is exhausted from the exhaust port 24.

[0037] In the actuator A of this embodiment, the cap portion 55 is attached to the holding portion 45 such that the cylindrical peripheral wall portion 58 extending from the periphery of the ceiling portion 56 is positioned on the inner or outer circumference (in this embodiment, the inner circumference) of the cylindrical portion 47 that covers at least the entire side of the base of the squib 37 (specifically, the main body portion 38 of the squib 37) in the holding portion 45. In other words, in the actuator A of this embodiment, with the cap portion 55 attached to the holding portion 45, the area around the squib 37 is covered almost without gap by the ceiling portion 56 and the peripheral wall portion 58. As a result, the airtightness is good, and when the squib 37 is operated, the combustion gas G generated can quickly press against the ceiling portion 56, making it possible to quickly release the connection with the connecting cord portion 27, which is a connecting means extending from the airbag 20.

[0038] Therefore, in the actuator A of this embodiment, good airtightness can be ensured, and the connection with the connecting cord portion 27 extending from the airbag 20 can be quickly released during operation.

[0039] Furthermore, in the actuator A of this embodiment, the cap portion 55 is configured to move the ceiling portion 56 while detaching the peripheral wall portion 58 from the cylindrical portion 47 when the pressure of the combustion gas G is received by the ceiling portion 56. In other words, in the actuator A of this embodiment, the cap portion 55 is configured to detach from the holding portion 45 without damaging the peripheral wall portion 58. Therefore, compared to the cap portion of a conventional actuator configured to have two legs extending from the ceiling portion, the cap portion 55 does not have a locally large protruding part, and damage when it detaches from the holding portion 45 and scatters can be suppressed.

[0040] Furthermore, in the actuator A of this embodiment, the peripheral wall portion 58 of the cap portion 55 is positioned on the inner circumference side of the cylindrical portion 47 of the holding portion 45, and the peripheral wall portion 58 is configured to completely cover the side surface 38b of the squib 37 (main body portion 38) with the tip-side region (tip-side portion 63). As a result, the combustion gas G generated when the squib 37 (main body portion 38) is operated can be quickly directed towards the ceiling portion 56 without being directed to the side of the main body portion 38. In addition, compared to the case in which the peripheral wall portion is positioned on the outer circumference side of the cylindrical portion, the size of the cap portion 55 (specifically, the size of the peripheral wall portion 58) can be made more compact, and from this point of view as well, damage after scattering can be further suppressed. If these points are not considered, a cap portion with a peripheral wall portion positioned on the outer circumference side of the cylindrical portion of the holding portion may be used. Furthermore, even when the peripheral wall portion is positioned on the inner circumference side of the cylindrical portion of the holding part, the area at the tip of the peripheral wall portion may be configured so as not to cover the side surface of the squib.

[0041] Furthermore, in the actuator A of this embodiment, the cap portion 55 is configured to curve the inner circumferential surface 55a from the peripheral wall portion 58 (specifically, the base portion 59 that faces the ceiling portion 56) to the ceiling portion 56 in a hemispherical shape. Therefore, when the combustion gas G presses against the ceiling portion 56 during the operation of the squib 37, the pressure can be applied almost uniformly to this hemispherical curved region (curved surface portion 70).

[0042] Furthermore, in the actuator A of the embodiment, the cover 39 that covers the outer circumference of the gas generating agent (not shown) in the squib 37 is configured to open radially when operated, by breaking the area of ​​the disc-shaped top plate portion 39a that covers the cap portion 55 starting from near the center and dividing it into multiple parts. However, the inner circumferential surface 55a side (curved surface portion 70) of the cap portion 55 is curved in a hemispherical shape and does not have any parts that partially protrude into the area corresponding to the trajectory when the cover 39 (top plate portion 39a) opens. Therefore, it is possible to suppress the cover 39 (top plate portion 39a) from hitting the area on the inner circumferential surface side of the cap portion 55 during the opening process, and the cover 39 (top plate portion 39a) can be opened quickly. In particular, in the actuator A of the embodiment, the inner diameter dimension d2 of the curved surface portion 70 is set to be approximately the same as the outer diameter dimension D5 of the main body portion 38 of the squib 37, and the separation distance L5 between the center of the curved surface portion 70 and the main body portion 38 when the cap portion 55 is attached to the holding portion 45 is set to be slightly larger than the radius dimension of the main body portion 38 (1 / 2 of the outer diameter dimension D5). That is, in the actuator A of the embodiment, when the cover 39 is operated, the disc-shaped top plate portion 39a, which is positioned opposite the ceiling portion 56, is broken starting from near the center and opens radially in multiple parts, and contact with the inner circumferential surface 55a of the cap portion 55 can be accurately suppressed until the opening is almost complete (see the dashed line in Figure 8), and the volume of the space in the area surrounded by the main body portion 38 and the cap portion 55 of the squib 37 (the space where the combustion gas G during operation is temporarily filled) is set to the minimum necessary. Therefore, the pressing force of the combustion gas G generated when the squib 37 operates can be efficiently applied to the cap portion 55 while minimizing losses.

[0043] In the actuator A of this embodiment, the locking recess 48 formed on the inner circumferential surface 47a side of the cylindrical portion 47 of the holding portion 45, and the locking projection 66 formed on the outer circumferential surface 63a side of the peripheral wall portion 58 (tip end portion 63) of the cap portion 55, are both formed around the entire circumference of the cylindrical portion 47 or the tip end portion 63. Therefore, when attaching the cap portion 55 to the holding portion 45, there is no need to consider the orientation, etc., resulting in good ease of installation. Furthermore, the locking projection and locking recess are formed on the cylindrical portion 47 or the tip end portion 63. Compared to the case where the part is partially provided, the amount of protrusion of the locking projection 66 (the amount of recess of the locking recess 48) can be set to be relatively small. In particular, in the actuator A of the embodiment, the locking projection 66 is configured to have inclined surfaces 66a on both ends (left end and right end) of the peripheral wall portion 58 (tip end portion 63) on the side that is inserted into the cylindrical portion 47, and the inclination angle γ of these inclined surfaces 66a with respect to the outer peripheral surface 63a is set to be small. In other words, the locking projection 66 is The tip portion 63 is formed to have a gently rising shape on the side in the direction of insertion into the cylindrical portion 47. The locking recess 48 also has an inclined surface 48a that corresponds to the inclined surface 66a of the locking projection 66. Therefore, when attaching the cap portion 55 to the holding portion 45, if the top portion 56 is moved in a way that pushes it toward the holding portion 45, the locking projection 66 can be driven into the locking recess 48 with relatively little force and locked to the periphery of the locking recess 48. Furthermore, when the squib 37 is in operation, the locking projection 66 can be smoothly removed from the locking recess 48 when the cap portion 55 moves due to the pressure on the ceiling portion 56 by the combustion gas G, thereby preventing damage to the locking projection 66 and the peripheral parts of the locking recess 48. The inclination of the tip surface 50 provided on the front end 47c side of the cylindrical portion 47 of the holding portion 45 is also formed with such ease of installation and the detachment of the cap portion 55 when the squib 37 is in operation in mind.

[0044] Furthermore, if the points mentioned above are not taken into consideration, the locking projections and locking recesses do not need to be formed around the entire circumference; for example, they may be arranged at multiple locations in a radial pattern. Alternatively, contrary to the embodiment, the locking projections may be provided on the holding portion side and the locking recesses on the cap portion side. However, from the viewpoint of suppressing damage after scattering, it is preferable to arrange the locking projections on the cap portion side rather than the locking recesses, which would result in a partially thin-walled area.

[0045] In this embodiment, a connecting cord portion 27, made of a flexible, narrow strip, is used as a connecting means extending from the airbag 20, and a loop portion 28 serving as an insertion hole is provided at the tip 27b of the connecting cord portion 27. In this embodiment, the external shape (internal diameter) of the loop portion 28 is set to allow insertion of the base portion 59 of the cap portion 55, but to prevent insertion of the ceiling portion 56 of the cap portion 55, which will be described later. The external shape (internal diameter) of the loop portion is not limited to this embodiment, and the external shape (internal diameter) of the loop portion may be set to allow insertion of both the base portion and the ceiling portion of the cap portion. Furthermore, even if the external shape (internal diameter) of the loop portion is set to be large in this way, in the actuator of this embodiment, the mounting bracket for attaching the actuator body is equipped with restricting pieces that cover the front and rear sides (both sides) of the base portion of the cap portion, so that the loop portion can be effectively prevented from coming out of the actuator body. Of course, instead of a string-like body as in the embodiment, a flexible strip-like body with an insertion hole at its tip may be used as the connecting means.

[0046] Furthermore, although the embodiment described an airbag system for a steering wheel as an example of an airbag system using an actuator, the airbag system that can use the actuator of the present invention is not limited to a steering wheel, and the actuator of the present invention may also be used in a passenger-side airbag system. Also, although the embodiment describes a configuration in which the internal pressure of the airbag is controlled by the actuator, the control of the airbag inflation state is not limited to internal pressure control, and the actuator of the present invention may also be used to control the completed inflation shape of the airbag. [Explanation of Symbols]

[0047] 9...Inflator, 11...Case (storage area), 12...Bottom wall, 15...Airbag cover, 20...Airbag, 27...Connecting string (connecting means), 28...Loop (insertion hole), 35...Actuator body, 37...Squib, 38...Main body, 38b...Side, 45...Holding part, 47...Cylindrical part, 48...Locking recess, 55...Cap part, 55a...Inner circumferential surface, 56...Top part, 58...Circumferential wall part, 66...Locking projection, 70...Curved surface part, 90...Control device, MD...Driver (occupant), W...Steering wheel, M...Airbag device, A...Actuator.

Claims

[Claim 1] It is attached to the storage area where the folded airbag is stored, and connects a connecting means extending from the airbag, and is configured to control the inflation state of the airbag by maintaining or releasing the connection with the connecting means. An actuator for an airbag device comprising a squib, a holding portion that holds the squib at one end, and a cap portion disposed on the other end of the holding portion so as to face the squib, The holding portion includes a cylindrical portion that holds the squib at one end and covers at least the entire circumference of the side of the squib on the base side, The aforementioned cap portion, The ceiling portion is positioned opposite the squib, A peripheral wall portion is arranged to cover the inner or outer circumference of the cylindrical portion, extending from the periphery of the ceiling portion. The configuration includes such a feature that closes the other end of the holding portion, The cap portion is configured to be attached to the holding portion by locking the peripheral wall portion to the cylindrical portion, and when attached to the holding portion, it is possible to maintain the inserted state of the cylindrical portion or the peripheral wall portion in the insertion hole formed on the tip side of the connecting means, and when the ceiling portion receives the pressure of the combustion gas generated when the squib is operating, the connection with the connecting means can be released by moving the ceiling portion while detaching the peripheral wall portion from the cylindrical portion. The peripheral wall portion is positioned on the inner circumference side of the cylindrical portion, and the tip-side region is configured to completely cover the side surface of the squib without any gaps. An actuator for an airbag device, characterized in that the cap portion is configured such that the inner circumferential surface from the peripheral wall portion to the ceiling portion is curved in a hemispherical shape.

Images