Actuator for airbag systems

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 inflation state of an airbag. [Background technology]

[0002] Conventionally, an actuator used to control the inflation state of an airbag in an airbag device has a configuration in which a cap portion arranged to face the squib is attached to a holding portion configured to hold a squib at one end and open at the other end. In this actuator, the cap portion has a flat ceiling portion and two legs extending from the ceiling portion, and is attached to the other end of the holding portion by engaging a locking protrusion provided at the tip end of the legs with a locking recess provided on the holding portion (see, for example, Patent Document 1). In this actuator, the tip end of a connecting member extending from the airbag is inserted into a region between the ceiling portion and the holding portion in the cap portion to connect the connecting member, and the ceiling portion is pressed by the pressure of combustion gas generated when the squib is activated, and the locking recess is released from the engagement state of the locking protrusion, thereby releasing the connection with the connecting means. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2023-90502 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional actuator, the connecting member is inserted into the portion between the ceiling and the holding portion of the cap, and thus a gap for inserting the connecting member is formed between the ceiling of the cap and the tip of the holding portion. Furthermore, in the conventional actuator, the cap is connected to the holding member by using two legs extending from the ceiling, and the holding portion is not closed by the cap. Therefore, in terms of quickly pressing the ceiling by the pressure of the combustion gas generated from the squib during operation, there is room for improvement in airtightness when the cap is attached to the holding portion (when mounted on the vehicle).

[0005] The present invention is devised to solve the above-mentioned problems, and aims to provide an actuator for an airbag device that can ensure good airtightness and, when activated, can quickly release the connection with a connecting member extending from the airbag. [Means for solving the problem]

[0006] The actuator for an airbag device according to the present invention is attached to a storage portion side in which a folded airbag is stored, and is configured to be capable of controlling the inflation state of the airbag by connecting a connecting means extending from the airbag and maintaining or releasing a connected state with the connecting means, An actuator for an airbag device, comprising: a squib; a holder for holding the squib at one end; and a cap disposed at the other end of the holder so as to face the squib, the holding portion holds the squib at one end and includes a cylindrical portion capable of covering at least the entire periphery of a side of the base portion of the squib; The cap part is a ceiling portion disposed opposite the squib; A peripheral wall portion that is cylindrical and extends from the periphery of the ceiling portion and is arranged to cover the inner or outer periphery of the cylindrical portion; and configured to close the other end side of the holding portion, The cap portion is configured to be attached to the holding portion by engaging the peripheral wall portion with the cylindrical portion, so that when attached to the holding portion, the inserted state of the cylindrical portion or the peripheral wall portion can be maintained 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 activated, the peripheral wall portion can be detached from the cylindrical portion while moving the ceiling portion, thereby releasing the connection with the connecting means.

[0007] In the actuator for an airbag device of the present invention, the cap portion is attached to the retaining portion such that the cylindrical peripheral wall portion extending from the periphery of the ceiling portion is disposed on the inner or outer circumferential side of a cylindrical portion of the retaining portion that covers at least the entire periphery of the side of the base portion of the squib. That is, in the actuator for an airbag device of the present invention, when the cap portion is attached to the retaining portion, the periphery of the squib is covered with almost no gaps by the ceiling portion and the peripheral wall portion or the cylindrical portion of the retaining portion. This provides good airtightness, and when the squib is activated, the generated combustion gas can quickly press the ceiling portion, thereby enabling the squib to be quickly released from its connection with the connecting means extending from the airbag.

[0008] Therefore, in the actuator for an airbag device of the present invention, good airtightness can be ensured, and when activated, the connection with the connecting member extending from the airbag can be quickly released.

[0009] In the actuator for an airbag device of the present invention, the cap portion is configured to move the ceiling portion while separating the peripheral wall portion from the cylindrical portion when the ceiling portion receives the pressure of the combustion gas. That is, in the actuator for an airbag device of the present invention, the cap portion is configured to come off 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 portion, and it is possible to suppress damage when the cap portion comes off the holding portion and is scattered.

[0010] Furthermore, in the actuator for an airbag device of the present invention, if the peripheral wall portion is positioned on the inner periphery of the tubular portion and is configured so that the tip region covers the side surface of the squib without any gaps, the side surface of the squib will be covered without any gaps by the peripheral wall portion extending from the ceiling portion, and therefore it is possible to direct the combustion gas generated when the squib is activated quickly towards the ceiling portion without it flowing sideways towards the squib, which is preferable.

[0011] Furthermore, in the actuator for an airbag device having the above-mentioned configuration, if the cap portion is configured with the inner surface side from the peripheral wall portion to the ceiling portion curved into a hemispherical shape, when the combustion gas presses against the ceiling portion, pressure can be applied approximately evenly to this hemispherically curved area, which is preferable. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic diagram showing a steering wheel airbag device using an actuator according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a vertical sectional view of the steering wheel airbag device of FIG. [Diagram 3] 2 is a partially enlarged bottom view showing an inflator and an actuator of the embodiment in the steering wheel airbag device of FIG. 1. FIG. [Figure 4] 2 is a schematic diagram showing an airbag used in the airbag device of FIG. 1 and the area around a vent hole in the airbag. [Diagram 5] FIG. 4 is a partially enlarged bottom view showing the actuator in FIG. [Figure 6] 1A and 1B are schematic perspective views showing an actuator according to an embodiment, showing a state seen from a cap portion side and a state seen from a holding portion side. [Figure 7] FIG. 2 is a schematic exploded perspective view showing a cap portion and a holding portion in the actuator of the embodiment. [Figure 8] FIG. 2 is a longitudinal cross-sectional view taken along the left-right direction of the actuator according to the embodiment. [Figure 9]9 is a longitudinal cross-sectional view taken along the front-rear direction of the actuator of FIG. 8, showing a base side region of a peripheral wall portion of a cap portion. FIG. [Figure 10] 1 is a vertical cross-sectional view of the actuator according to the embodiment, showing a state in which a cap portion and a holding portion holding a squib are arranged side by side. [Figure 11] 4 is a partially enlarged vertical cross-sectional view showing a portion of a locking projection and a locking recess in the actuator of the embodiment. FIG. [Figure 12] 4 is a partially enlarged cross-sectional view showing a locking protrusion provided on a cap portion and a locking recess provided on a holding portion in the actuator of the embodiment. FIG. [Figure 13] 3A and 3B are vertical cross-sectional views showing the actuator of the embodiment before and after actuation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] An embodiment of the present invention will be described below with reference to the drawings. In this 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 disposed on an upper portion of a boss portion B in the center of the steering wheel main body 1. In this embodiment, the steering wheel main body 1 includes a ring portion R that is gripped when steering, a boss portion B that is disposed approximately in the center of the ring portion R and connected to a steering shaft SS, and a predetermined number of spoke portions (not shown) that connect the boss portion B and the ring portion R.

[0014] In the embodiments, unless otherwise specified, the front-rear, up-down, and left-right directions are based on the steering wheel W mounted on the vehicle being steered straight ahead, and the up-down direction is the up-down direction along the axial direction of the steering shaft SS (see Figure 2) to which the steering wheel W is attached, the front-rear direction is the front-rear direction of the vehicle which is perpendicular to the axis of the steering shaft SS, and the left-right direction is the left-right direction of the vehicle which is perpendicular to the axis of the steering shaft SS.

[0015] As shown in Figures 1 and 2, the steering wheel body 1 comprises a core metal 2 made of a metal such as an aluminum alloy and arranged to connect the various parts of the ring portion R and the boss portion B, a synthetic resin coating layer 3 that covers the core metal 2 in the areas of the ring portion R and the spoke portion (not shown), and a synthetic resin lower cover 4 that covers the lower part of the boss portion B.

[0016] As shown in FIG. 2, the airbag device M includes an airbag 20, an inflator 9 that supplies inflation gas to the airbag 20, a case 11 as a storage portion that stores 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] 2, the inflator 9 includes a substantially cylindrical main body 9a having a plurality of gas discharge ports 9b, and a flange 11c for mounting the inflator 9 to the case 11. The flange 9c is formed with through holes (not shown) for passing the bolts 7a of the retainer 7 therethrough. The inflator 9 is electrically connected to a control device 90, which will be described later.

[0018] In this embodiment, the inflator 9 of the airbag device M and a squib 37 (described later) of the actuator A are configured so that their operation is controlled by a control device 90 shown in FIG.

[0019] 1, the control device 90 is electrically connected to occupant detection sensors 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, and is also electrically connected to a collision detection sensor 94 capable of detecting the acceleration and acceleration direction of the vehicle, and inputs electrical signals from the position detection sensor 92, weight detection sensor 93, or collision detection sensor 94 to operate the inflator 9 of the airbag device M and also to operate the squib 37 of the actuator A. In the case of the embodiment, the operation of the squib 37 of the actuator A is controlled by the control device 90 so as to be able to control the rise in internal pressure of the airbag 20 when the airbag 20 is inflated by the operation of the inflator 9. Specifically, the operation of the squib 37 of actuator A is controlled so as to exhaust the inflation gas that has flowed into the airbag 20 to the outside of the airbag 20, thereby inflating the airbag 20 in a suitable inflation mode.

[0020] The case 11 serving as the storage portion is made of sheet metal and includes a bottom wall portion 12 having a substantially rectangular plate shape into which the inflator 9 is inserted from below and a peripheral wall portion 13 extending vertically from the outer periphery of the bottom wall portion 12, as shown in Fig. 2. In the bottom wall portion 12, in a region in front of an opening (not shown) through which the main body portion 9a of the inflator 9 is inserted, there are formed an insertion hole 12a through which a connecting string portion 27 as a connecting means extending from the airbag 20 as described later is inserted, an attachment hole 12b through which a mounting bracket portion 75 of the actuator A as described later is attached, and a through hole 12c through which a protruding piece 79 formed on the mounting bracket portion 75 is inserted (see Figs. 3, 5, 6B, 8, 9). On the upper end side of the peripheral wall portion 13, there is formed an attachment piece (not shown) extending outward. In the embodiment, the airbag device M is configured to be mounted on the upper part of the boss part B of the steering wheel main body 1 already attached to the steering shaft SS by attaching and fixing the case 11 to the core metal 2 of the steering wheel W using the mounting board of the horn switch mechanism attached to the mounting piece (not shown). In addition, a side wall part 15c of the airbag cover 15 is attached to the peripheral wall part 13 of the case 11 using rivets 16 or the like (see FIG. 2). In the case of the embodiment, the airbag 20 and the inflator 9 are attached to the bottom wall part 12 of the case 11 by passing the bolt 7a (see FIG. 3) of the retainer 7 arranged in the airbag 20 through the periphery of the inflow opening 21 of the airbag 20 (described later), the bottom wall part 12 of the case 11, and the flange part 9c of the inflator 9, and fastening with a nut 8, using a bolt 7a (see FIG. 3) of the retainer 7 arranged in the airbag 20 as a mounting means.

[0021] The airbag cover 15 is made of synthetic resin and includes a ceiling wall portion 15a that covers the upper part of the airbag 20 housed in the case 11, and a substantially rectangular cylindrical side wall portion 15c that extends downward from near the outer periphery of the ceiling wall portion 15a (see FIG. 2). The ceiling wall portion 15a is formed with two doors 15b, 15b that are pushed by the inflating airbag 20 to open forward and backward.

[0022] The airbag 20 is a bag-shaped bag made of flexible woven fabric made of polyamide yarn, polyester yarn, or the like, and inflates to cover the upper surface of the steering wheel W by introducing inflation gas into the inside as shown by the two-dot chain line in FIG. 1. The airbag 20 has an inlet opening 21 as shown in FIG. 4A. The inlet opening 21 is for inserting the main body 9a of the inflator 9 from below, and a mounting hole 22 is formed around the periphery of the inlet opening 21 for inserting the bolt 7a of the retainer 7. In addition, a circular exhaust hole 24 is formed in front of the inlet opening 21 in the airbag 20, and insertion holes 23A and 23B are formed between the exhaust hole 24 and the inlet opening 21 at two locations, near the rear edge of the exhaust hole 24 and near the front edge of the inlet opening 21, through which a connecting string 27 serving as a connecting means can be inserted (see FIG. 4A). Each of the insertion holes 23A, 23B is formed in a slit shape extending substantially along the left-right direction so that the connecting string portion 27 can be inserted therethrough.

[0023] A flap 26 is disposed on the outer periphery of the airbag 20 so as to close the exhaust hole 24. The flap 26 is formed of flexible woven fabric made of polyester yarn, polyamide yarn, or the like, similar to the airbag 20, and has an outer shape that is substantially rectangular so as to be able to close the exhaust hole 24. One side (front side) of the flap 26 that is away from the inlet opening 21 is joined to the front edge side of the exhaust hole 24, and a base part 27a of a connecting string part 27 that serves as a connecting means that is connected to an actuator main body 35 described later is connected to a side (rear side) that is opposite to the side that is on the inlet opening 21 side. The connecting string part 27 that serves as the connecting means is made of a flexible narrow belt-like body, and is disposed substantially along the front-rear direction when the airbag 20 is deployed flat. A loop portion 28 is formed on the tip 27b side of the connecting cord portion 27, through which a peripheral wall portion 58 (specifically, a base portion side portion 59) of a cap portion 55 of the actuator body 35, which will be described later, can be inserted. That is, in the embodiment, the loop portion 28 constitutes an insertion hole through which the base portion side portion 59 of the cap portion 55 can be inserted. The loop portion 28 has an outer shape (inner diameter dimension) set to a dimension that allows the base portion side portion 59 of the cap portion 55 to be inserted but does not allow a ceiling portion 56 of the cap portion 55, which will be described later, to be inserted. The length dimension of the connecting cord portion 27 is set to a dimension that allows the airbag 20 to be inflated without hindrance even in a state in which the connecting state of the tip 27b side with the actuator body 35 is maintained. The connecting string part 27 is inserted through the insertion holes 23A, 23B formed in the airbag 20 so that the base 27a side and the tip 27b side are disposed on the outer periphery of the airbag 20 and the intermediate part is disposed on the inner periphery of the airbag 20, with the flap 26 covering the outer periphery of the exhaust hole 24, and while maintaining this state, it is folded together with the airbag 20 and stored in the case 11. When mounted on the vehicle, the tip 27b of the connecting string part 27 protrudes from the insertion hole 12a of the case 11, and is connected to the actuator main body 35 by inserting the loop part 28 through the peripheral wall part 58 (base side part 59) of the cap part 55 of the actuator main body 35 (see A in Figs. 5 to 7 and 8).

[0024] In the embodiment, the airbag 20 inflates in two inflation modes: an open mode in which the exhaust hole 24 is opened, and a closed mode in which the exhaust hole 24 is kept closed. Specifically, in a state in which the actuator body 35 is not actuated and the connection between the tip 27b of the connecting cord part 27 and the actuator body 35 is kept (a state in which the insertion state of the base part side part 59 of the cap part 55 into the loop part 28 is kept, see A in FIG. 13), the tip side of the flap 26 is pressed by the base part 27a of the connecting cord part 27, and the airbag 20 inflates in the closed mode in which the flap 26 closes the exhaust hole 24, as shown in B in FIG. 4. When the actuator body 35 is actuated, the cap portion 55 is detached from the holding portion 45 (described later) constituting the actuator body 35, the peripheral wall portion 58 of the cap portion 55 is released from the loop portion 28, and the connection between the connecting string portion 27 and the actuator body 35 is released (see B in FIG. 13), the flap 26 is pushed by the inflation gas flowing out of the exhaust hole 24, and the flap 26 opens, and the airbag 20 is inflated in the open mode with the exhaust hole 24 open, as shown in C in FIG. 4. The airbag 20 completes inflation in a state in which the internal pressure is maintained in the closed mode, and in which an increase in the internal pressure is suppressed in the open mode. The actuation of the actuator body 35 is controlled by the control device 90. In the embodiment, when the control device 90 detects, based on a signal from the position detection sensor 92, that the driver MD is excessively close to the steering wheel W, or detects, based on a signal from the weight detection sensor 93, that the driver MD is small in stature, the control device 90 operates the actuator body 35 simultaneously with or slightly delayed from the operation of the inflator 9 so as to reduce the internal pressure of the airbag 20 during inflation.

[0025] In this embodiment, the actuator A is disposed in a region in front of the inflator 9, as shown in Figures 2 and 3. As shown in Figures 5 and 6A and 6B, the actuator A includes an actuator body 35 and a mounting bracket portion 75 for mounting the actuator body 35 to the case 11 serving as a storage portion.

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

[0027] As shown in Fig. 8, the squib 37 includes a main body 38 and a pair of conductive pins 40, 40 extending leftward from the main body 38. The conductive pin 40 is disposed so that its tip side is exposed from the left side of a base 46 (described later) in the holding part 45, and is a portion for connecting a connector (not shown) that is electrically connected to the control device 90. Although not shown in detail, the main body 38 is configured to store a gas generating agent capable of generating combustion gas therein, and the outer periphery of the gas generating agent is covered by a thin metal cover 39 made of an aluminum alloy or the like. The main body 38 is activated when an activation signal is input from the control device 90, and burns the gas generating agent. At this time, the cover 39 covering the outer periphery of the gas generating agent is broken starting from near the center in the area covering the cap portion 55 side of the gas generating agent (the area on the right end face 38a side of the main body portion 38, the area of ​​the disk-shaped top plate portion 39a), and is divided into multiple pieces, radially opening (see the two-dot chain lines in FIG. 8). The squib 37 is molded integrally with the holding portion 45 by insert molding when the holding portion 45 is formed, and is held by the holding portion 45.

[0028] As shown in Figs. 8 and 10B, the holding portion 45 includes a base portion 46 disposed on the base side (left end 45b side) and holding the squib 37 (specifically, the region from the left end face side of the main body portion 38 to the base side of the conductive pin 40), and a tubular portion 47 extending from the base portion 46 and capable of covering at least the side of the base side of the squib 37 (specifically, the main body portion 38) over the entire circumference. In addition, a protrusion 45c for positioning with respect to the mounting bracket portion 75 is formed on the outer peripheral surface side of the holding portion 45 at a position slightly left of the center in the left-right direction, protruding in a substantially rectangular shape. As described above, the conductive pin 40 of the squib 37 is disposed so that the tip side portion protrudes leftward from the left end face side of the base portion 46. The tubular portion 47 is substantially cylindrical, and is configured to have a gap between it and the side surface 38b of the main body portion 38 as shown in Fig. 10B, and has an opening on the tip side (right end side). In the embodiment, the cylindrical portion 47 is configured such that the tip (right end 47c) is positioned slightly forward of the right end face 38a of the main body portion 38 of the squib 37, and covers the entire periphery of the side of the main body portion 38. A locking recess 48 for locking a locking protrusion 66 formed on a peripheral wall portion 58 of the cap portion 55, which will be described later, is formed on the inner periphery 47a side of the cylindrical portion 47. The locking recess 48 is formed by recessing the inner periphery 47a near the tip (right end 47c) of the cylindrical portion 47, and in the embodiment, is disposed so as to be continuously recessed over the entire periphery of the cylindrical portion 47, as shown in Fig. 7 and Fig. 10B. More specifically, as shown in Fig. 12, the locking recess 48 is formed by recessing the inner peripheral surface 47a of the cylindrical portion 47 into a generally "L"-shaped cross section (so that the tip 48b of the recess located at the outermost position is located near the center of the left and right sides) so that two inclined surfaces 48a, 48a are arranged side by side on the left and right sides. The locking recess 48 has a recess amount L1 set to about 1 / 8 of the thickness dimension T1 of the cylindrical portion 47, and a width dimension L2 set to about 6 times the recess amount L1 and about 2 / 3 of the thickness dimension T1 of the cylindrical portion 47 (see Fig. 12). The inclined surface 48a has an inclination angle α (see Fig. 12) of about 20° with respect to the inner peripheral surface 47a of the cylindrical portion 47.In the 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 (coincident with the inner circumferential surface 47a) of the holding portion 45 so that the inner circumferential surface 47a side is located at the rightmost position in a cross section approximately along the front-rear direction. In detail, the tip surface 50 has an inclination angle β (see FIG. 12) with respect to the axial direction (inner circumferential surface 47a) set to about 60°. In the embodiment, the tip surface 50 is configured so that the outer edge 50a on the outer circumferential surface 47b side is located slightly to the right of the tip 48b of the recess in the locking recess 48, and is located at a position approximately coinciding with the right end surface 38a of the main body portion 38 in the squib 37 (see FIGS. 11 and 12). That is, the locking recess 48 is formed so that the tip 48b of the recess is located slightly to the left of the right end surface 38a of the main body portion 38.

[0029] As shown in Figs. 8 and 10A, the cap portion 55 includes a ceiling portion 56 disposed opposite the squib 37, and a cylindrical peripheral wall portion 58 extending from the peripheral edge of the ceiling portion 56. The ceiling portion 56 has a substantially circular plate-like outer shape. In the case of this embodiment, the outer diameter dimension D2 of the ceiling portion 56 is set to be substantially 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 Figs. 10A and B).

[0030] As shown in A of Fig. 10, the peripheral wall portion 58 has an outer shape that is substantially cylindrical with an open left end side that is the squib 37 side, and includes a base portion 59 located on the ceiling portion 56 side, and a tip portion 63 located on the squib 37 side and having an outer diameter dimension slightly smaller than that of the base portion 59. The peripheral wall portion 58 has an inner peripheral surface 58a side that is flush with the outer peripheral surface 58b side, and a step portion 61 is provided on the outer peripheral surface 58b side, so that the tip portion 63 has a smaller diameter than the base portion 59. That is, the base portion 59 is configured to be slightly thicker than the tip portion 63. In this embodiment, the tip portion 63 is configured to cover the inner peripheral side of the tubular portion 47 of the holding portion 45. The tip side portion 63 has an outer diameter D3 that is substantially equal to the inner diameter d1 of the cylindrical portion 47, and a thickness T2 that is equal to the opening width H of the gap between the cylindrical portion 47 and the main body portion 38 of the squib 37, and is set to a dimension that allows insertion into the gap between the cylindrical portion 47 and the main body portion 38 (see A and B in Fig. 10 and Fig. 12). When the cap portion 55 is attached to the holding portion 45, the tip side portion 63, which is the area on the tip side 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 gap (see A in Fig. 13). Although Figs. 6 and 11 show a slight gap between the side surface 38b of the main body portion 38 and the tip side portion 63, this gap is minute in reality. In this specification, "without a gap" includes a slight gap that occurs due to manufacturing errors between the side surface 38b of the main body 38 and the tip portion 63. In the case of 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 disposed with a slight gap between it and the base portion 46 of the holding portion 45 (see FIG. 11).

[0031] A locking projection 66 is formed on the outer peripheral surface 63a of the tip side portion 63 of the peripheral wall portion 58, and is inserted into and locked in a locking recess 48 formed on the inner peripheral surface 47a of the cylindrical portion 47 of the holding portion 45. The locking projection 66 is formed to protrude outward from the outer peripheral surface 63a at the approximate left-right center of the tip side portion 63, and is disposed to protrude continuously around the entire circumference of the tip side portion 63 in the embodiment, as shown in FIG. 7. The locking projection 66 is formed so that its cross-sectional shape in the direction approximately along the left-right direction is a flat, approximately trapezoidal shape, and its width dimension L4 is set to be approximately the same as the width dimension L2 of the locking recess 48, and its protrusion amount L3 is set to be approximately 1 / 2 the recess amount L1 of the locking recess 48 (see FIG. 12). The protrusion amount L3 of the locking projection 66 is set to be approximately 1 / 10 of the thickness dimension T2 of the tip side portion 63. The locking projection 66 is configured to have inclined surfaces 66a, 66a on the right and left ends. The inclined surfaces 66a are arranged corresponding to the inclined surfaces 48a formed in the locking recesses 48, and the inclination angle γ (see FIG. 12) with respect to the outer circumferential surface 63a of the tip side portion 63 is set to about 20°. The outer shape of the locking projection 66 (the amount of outward protrusion, the angle of the inclined surfaces 66a, the amount of protrusion with respect to the thickness dimension T2 of the tip side portion 63, and the dimensional difference with respect to the recess amount L1 of the locking recesses 48) is designed to suppress damage to the tip side portion 63 and the cylindrical portion 47 in the holding portion 45 when the locking with the locking recesses 48 is released during the operation of the actuator body 35, and to enable the tip side portion 63 to be detached from the cylindrical portion 47 (the cap portion 55 from the holding portion 45).

[0032] The base side portion 59 of the peripheral wall portion 58 has an outer diameter D4 set to about 4 / 5 of the outer diameter D2 of the ceiling portion 56 (see A in FIG. 10). This base side portion 59 is a portion that is exposed and disposed between the retaining portion 45 and the ceiling portion 56 in a state in which the cap portion 55 is attached to the retaining portion 45 (see FIG. 11), and in this embodiment, this base side portion 59 is inserted into the loop portion 28 formed on the tip end 27b side of the connecting cord portion 27 serving as a connecting means in the airbag 20, as shown in FIGS.

[0033] In the embodiment, the cap portion 55 is configured such that the inner circumferential surface 55a side from the peripheral wall portion 58 to the ceiling portion 56 is curved in a hemispherical shape. In detail, in the embodiment, the cap portion 55 is provided with a curved surface portion 70 curved in a hemispherical shape on the inner circumferential surface 55a side from the base portion side portion 59 to the ceiling portion 56 (see A in FIG. 10). In the embodiment, the curved surface portion 70 has an inner diameter dimension d2 set to be substantially the same as the outer diameter dimension D5 of the main body portion 38 in the squib 37 (see A and B in FIG. 10). In addition, the curved surface portion 70 is configured such that the separation distance L5 (see FIG. 8) between the center side of the curved surface portion 70 and the main body portion 38 in a state in which the cap portion 55 is attached to the holding portion 45 is set to be slightly larger than the radial 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 includes a main body portion 76 that is wrapped around the outer periphery of the holding portion 45 over the entire circumference as shown in Figs. 5A and 6B, and mounting portions 77 that are arranged on both ends of the main body portion 76 and bolted to the bottom wall portion 12 of the case 11 in a two-ply configuration. The mounting portion 77 is formed with an insertion hole 77a through which a bolt 82 can be inserted. In the main body portion 76, in an area covering the lower surface side of the holding portion 45, a through hole 78 that can pass through the protrusion portion 45c formed on the holding portion 45 is formed with an approximately rectangular opening. In addition, in an area on the right edge 76b side of the main body portion 76 and on the front end side, a protruding piece 79 is formed so as to protrude upward toward the bottom wall portion 12 of the case 11. The protruding piece 79 is inserted into a through hole 12c formed in the bottom wall 12, and is provided for positioning the actuator body 35 when it is attached to the bottom wall 12 using the mounting bracket 75. Furthermore, two restricting pieces 80, 80 are formed to extend forward on both left and right ends of the right edge 76a of the body 76. The restricting pieces 80 are disposed up to the vicinity of the ceiling 56 so as to cover the front and rear sides of the base side region 59 of the cap 55 (see Figs. 5 and 9), and are disposed to prevent the tip 27b side (loop portion 28) of the connecting string portion 27 from coming loose from the actuator body 35 when the actuator is mounted on the vehicle.

[0035] Next, the mounting of the actuator A and the airbag device M of the embodiment on a vehicle will be described. First, the airbag 20 is folded so as to be stored in the case 11 while maintaining the state in which the exhaust hole 24 is closed by the flap 26 with the retainer 7 disposed inside, and the connecting string part 27 is inserted into the insertion holes 23A and 23B and the tip 27b side is kept protruding from the insertion hole 23B. Thereafter, the folded airbag 20 is stored in the case 11. At this time, the tip 27b of the connecting string part 27 is made to protrude from the insertion hole 12a of the bottom wall part 12. The base part side part 59 of the cap part 55 in the actuator main body 35 is inserted into the loop part 28 formed at the tip 27b of the connecting string part 27. Next, the cap part 55 in a state in which the tip 27b (loop part 28) of the connecting string part 27 is penetrated is attached to the holding part 45 in a state in which the mounting bracket part 75 is attached, to form the actuator main body 35. When the mounting portion 77 of the mounting bracket is attached to the bottom wall 12 using the bolt 82 and nut 83, the actuator body 35 can be connected to the connecting cord portion 27 as a connecting member, and at the same time, the actuator A can be attached to the case 11. Next, the main body 9a of the inflator 9 is inserted from below, and the inflator 9 and the airbag 20 are attached to the case 11 using the bolt 7a and nut 8 of the retainer 7 protruding from the bottom wall 12. Furthermore, the airbag cover 15 is placed on the case 11, and the airbag cover 15 is attached to the case 11 using the rivet 16 or the like. Thereafter, the airbag device M can be assembled by assembling the horn switch mechanism (not shown) to the mounting piece (not shown) of the case 11. This airbag device M can be attached to the steering wheel body 1, which has been fastened to the steering shaft SS in advance, using the mounting board (not shown) of the horn switch mechanism. Thereafter, a connector (not shown) to which lead wires extending from the control device 90 are connected is connected to the squib 37 of the actuator body 35, and lead wires (not shown) extending from the control device 90 are also connected to the inflator 9, thereby allowing the airbag device M and actuator A to be mounted on the vehicle.

[0036] In the airbag device M of the embodiment, when inflation gas is discharged from the gas discharge port 9b of the inflator 9, the airbag 20 inflates with the inflation gas flowing therein, and while pushing open the door portions 15b, 15b of the airbag cover 15, the airbag protrudes from the case 11 and completes the inflation so as to cover almost the entire upper surface of the steering wheel W as shown by the two-dot chain line in Fig. 1. Then, at this time, in the actuator main body 35 of the actuator A, when the squib 37 is actuated in response to an actuation signal from the control device 90, the combustion gas G generated by the actuation of the squib 37 breaks open the cover 39 covering the outer periphery side of the main body portion 38, and is ejected toward the cap portion 55, and the combustion gas G presses against the ceiling portion 56 of the cap portion 55. The pressure of the combustion gas G is received by the ceiling portion 56 of the cap portion 55, and while the engagement between the engagement projection 66 and the engagement recess 48 is released, the peripheral wall portion 58 is detached from the cylindrical portion 47, and the cap portion 55 is released from the holding portion 45, and as shown in Fig. 13B, the cap portion 55 comes out of the loop portion 28 provided on the tip 27b side of the connecting cord portion 27, and is released from the connection with the connecting cord portion 27. Then, as shown in Fig. 4C, the flap 26 connected to the connecting cord portion 27 opens the exhaust hole 24 of the airbag 20, and the inflation gas is exhausted from the exhaust hole 24.

[0037] In the actuator A of the embodiment, the cap portion 55 is attached to the holding portion 45 in such a manner that the cylindrical peripheral wall portion 58 extending from the periphery of the ceiling portion 56 is disposed on the inner or outer circumferential side (inner circumferential side in the case of the embodiment) of the cylindrical portion 47 that covers at least the side of the base portion of the squib 37 (specifically, the main body portion 38 of the squib 37) over the entire circumference in the holding portion 45. That is, in the actuator A of the embodiment, when the cap portion 55 is attached to the holding portion 45, the periphery of the squib 37 is covered with almost no gaps by the ceiling portion 56 and the peripheral wall portion 58. Therefore, the airtightness is good, and when the squib 37 is activated, the generated combustion gas G can quickly press the ceiling portion 56, and the connection with the connecting cord portion 27 as a connecting means extending from the airbag 20 can be quickly released.

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

[0039] Furthermore, in the actuator A of the embodiment, the cap portion 55 is configured to move the ceiling portion 56 while separating 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. That is, in the actuator A of the embodiment, the cap portion 55 is configured to be removed 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 portion, and damage when the cap portion 55 is removed from the holding portion 45 and scattered can be suppressed.

[0040] Furthermore, in the actuator A of the embodiment, the peripheral wall 58 of the cap portion 55 is configured to be disposed on the inner periphery of the cylindrical portion 47 of the holding portion 45, and the peripheral wall 58 is configured to cover the side surface 38b of the squib 37 (main body portion 38) without any gaps with the tip side region (tip side portion 63). Therefore, the combustion gas G generated when the squib 37 (main body portion 38) is operated can be quickly directed toward the ceiling portion 56 without flowing toward the side of the main body portion 38. In addition, compared with the case where the peripheral wall is disposed on the outer periphery of the cylindrical portion, the size of the cap portion 55 (specifically, the size of the peripheral wall portion 58) can be made compact, and from this point of view, damage after scattering can be further suppressed. If such a point is not taken into consideration, a cap portion configured to have the peripheral wall portion disposed on the outer periphery of the cylindrical portion of the holding portion may be used. Also, even when the peripheral wall portion is disposed on the inner peripheral side of the cylindrical portion of the holder, the peripheral wall portion may be configured so as not to cover the side surface of the squib with the tip end region.

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

[0042] In the actuator A of the embodiment, the cover 39 covering the outer periphery of the gas generating agent (not shown) in the squib 37 is configured to break the area of ​​the disk-shaped top plate 39a covering the cap portion 55 side from the center and split into multiple pieces when actuated, and opens radially, but the inner periphery 55a side (curved surface portion 70) of the cap portion 55 is curved hemispherically and does not have a part that protrudes partially into the area that corresponds to the trajectory of the cover 39 (top plate portion 39a) when it is opened. Therefore, it is possible to prevent the cover 39 (top plate portion 39a) from hitting the area on the inner periphery side of the cap portion 55 during opening, 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 substantially 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 side of the curved surface portion 70 and the main body portion 38 in a state in which the cap portion 55 is attached to the holding portion 45 is set to be slightly larger than the radial dimension (1 / 2 of the outer diameter dimension D5) of the main body portion 38. That is, in the actuator A of the embodiment, when the disk-shaped top plate portion 39a arranged opposite the ceiling portion 56 of the cover 39 is broken starting from near the center and radially opened so as to be divided into multiple pieces during operation, it is possible to reliably prevent the disk-shaped top plate portion 39a from coming into contact with the inner circumferential surface 55a of the cap portion 55 until the opening is substantially completed (see the two-dot chain line in FIG. 8), and the volume of the space (the space once filled with the combustion gas G during operation) surrounded by the main body portion 38 of the squib 37 and the cap portion 55 is set to the minimum necessary. Therefore, the pressing force of the combustion gas G generated when the squib 37 is acted on the cap portion 55 efficiently while minimizing loss.

[0043] In the actuator A of the embodiment, the locking recess 48 formed on the inner circumferential surface 47a of the cylindrical portion 47 of the holding portion 45 and the locking projection 66 formed on the outer circumferential surface 63a of the peripheral wall portion 58 (tip side portion 63) of the cap portion 55 are both formed over the entire circumference of the cylindrical portion 47 or the tip side portion 63. Therefore, when attaching the cap portion 55 to the holding portion 45, it is not necessary to take into consideration the direction, etc., and the attachment workability is good. In addition, the locking projection and the locking recess In comparison with the case where the locking projection 66 is partially provided, the amount of protrusion of the locking projection 66 (the amount of recess of the locking recess 48) can be set 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 and right ends) of the peripheral wall portion 58 (tip end portion 63) in the insertion direction into the tubular portion 47, and the inclination angle γ of the inclined surfaces 66a with respect to the outer circumferential surface 63a is set small. In other words, the locking projection 66 is , and is formed so as to rise gently on the side along the direction of insertion of the tip end portion 63 into the tubular portion 47. The locking recess 48 also has an inclined surface 48a formed therein corresponding to the inclined surface 66a of the locking projection 66. Therefore, when the ceiling portion 56 is moved so as to be pushed toward the holding portion 45 when the cap portion 55 is attached to the holding portion 45, the locking projection 66 can be inserted into the locking recess 48 with a relatively light force and locked onto the periphery of the locking recess 48. Furthermore, when the squib 37 is activated, even when the cap portion 55 moves as the combustion gas G presses the ceiling portion 56, the locking projection 66 can be smoothly removed from the locking recess 48, preventing damage to the locking projection 66 and the peripheral portion 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 holder 45 is also formed in consideration of such ease of installation and detachment of the cap portion 55 when the squib 37 is activated.

[0044] If the above-mentioned points are not taken into consideration, the locking projections and locking recesses do not have to be formed around the entire circumference, and may be arranged, for example, at multiple radial locations. Also, contrary to the embodiment, the locking projections may be arranged on the holding portion side, and the locking recesses on the cap portion side. However, from the viewpoint of suppressing breakage after scattering, it is preferable to arrange the locking projections on the cap portion side, rather than the locking recesses, which will have a partially thin-walled area.

[0045] In the embodiment, a connecting string 27 made of a flexible narrow belt is used as a connecting means extending from the airbag 20, and a loop 28 as an insertion hole is disposed on the tip 27b side of the connecting string 27. In the embodiment, the loop 28 has an outer shape (inner diameter dimension) set to a dimension that allows the base side portion 59 of the cap portion 55 to be inserted therethrough, but does not allow the cap portion 55 to have a ceiling portion 56 (described later) to be inserted therethrough. The outer shape (inner diameter dimension) of the loop is not limited to the embodiment, and the outer shape (inner diameter dimension) of the loop may be set to a dimension that allows both the base side portion and the ceiling portion of the cap portion to be inserted therethrough. Even if the outer shape (inner diameter dimension) of the loop is set to be large in this way, in the actuator of the embodiment, the mounting bracket for mounting the actuator body has a restricting piece that covers the front and rear sides (both sides) of the base side of the cap portion, so that the loop can be reliably prevented from coming off the actuator body. Of course, the connecting means may not be a string-like body as in the embodiment, but may be a flexible band-like body with an insertion hole opened at the tip side.

[0046] In addition, in the embodiment, an airbag device for a steering wheel has been taken as an example of an airbag device using an actuator, but the airbag device for which the actuator of the present invention can be used is not limited to an airbag device for a steering wheel, and the actuator of the present invention may be used in an airbag device for a passenger seat. Also, in the embodiment, the internal pressure of the airbag is controlled by the actuator, but the control of the inflation state of the airbag is not limited to the internal pressure control, and the actuator of the present invention may be used to control the shape of the airbag when it is fully inflated. [Explanation of symbols]

[0047] 9...inflator, 11...case (storage area), 12...bottom wall portion, 15...airbag cover, 20...airbag, 27...connecting string portion (connecting means), 28...loop portion (insertion hole), 35...actuator main body, 37...squib, 38...main body portion, 38b...side surface, 45...holding portion, 47...cylindrical portion, 48...locking recess, 55...cap portion, 55a...inner surface, 56...ceiling portion, 58...circumferential wall portion, 66...locking projection, 70...curved surface portion, 90...control device, MD...driver (occupant), W...steering wheel, M...airbag device, A...actuator.

Claims

1. The airbag control device is attached to a storage portion side in which a folded airbag is stored, and is configured to connect a connecting means extending from the airbag, and to control the inflated state of the airbag by maintaining or releasing the connection state with the connecting means, An actuator for an airbag device comprising: a squib; a holder for holding the squib at one end; and a cap disposed at the other end of the holder so as to face the squib, the holding portion holds the squib at one end and includes a cylindrical portion capable of covering at least the entire periphery of a side of the squib on a base portion side, The cap portion is a ceiling portion disposed opposite the squib; a peripheral wall portion that is cylindrical and extends from the periphery of the ceiling portion and is arranged to cover an inner peripheral side or an outer peripheral side of the cylindrical portion; and configured to close the other end side of the holding portion, an actuator for an airbag device, characterized in that the cap portion is configured to be attached to the retaining portion by engaging the peripheral wall portion with the cylindrical portion, so that when attached to the retaining portion, the inserted state of the cylindrical portion or the peripheral wall portion can be maintained in an insertion hole formed on the tip side of the connecting means, and when the ceiling portion receives the pressure of combustion gas generated when the squib is activated, the connection with the connecting means can be released by moving the ceiling portion while separating the peripheral wall portion from the cylindrical portion.

2. 2. The actuator for an airbag device according to claim 1, wherein the peripheral wall portion is disposed on an inner peripheral side of the cylindrical portion, and is configured so that a tip end region of the peripheral wall portion covers a side surface of the squib without any gaps.

3. 3. The actuator for an airbag device according to claim 2, wherein the cap portion has an inner circumferential surface side extending from the peripheral wall portion to the ceiling portion curved in a semispherical shape.

Images