Actuator

Abstract

The present invention provides an actuator having a bottomed cylindrical member that is easily manufactured and configured not to damage the seat belt retractor during operation. [Solution] The actuator 100 comprises a bottomed cylindrical member 10 and a holder 40 that holds the bottomed cylindrical member 10 and the igniter 30. The bottomed cylindrical member 10 is a bottomed cylindrical member having an opening at one end, and comprises a bottom portion 11, a cylindrical portion 12, a hole portion 13, a flange portion 14, and an open end portion 15. The bottom portion 11 is provided at the other end of the bottomed cylindrical member 10, and a hole portion 13 is formed in the center. Around the hole portion 13 of the bottom portion 11, a plurality of groove-shaped scores 17 are formed at equal angles with respect to the center of the hole portion 13 and along the radial direction from the center of the hole portion 13. The open end portion 15 covers the cap member 31 side, which is the part of the igniter 30 that generates thermal energy.

Description

[Technical Field]

[0001] The present invention relates to an actuator that pushes out a piston member. [Background Art]

[0002] Conventionally, a webbing retractor is known that can absorb the impact energy of an occupant while retracting webbing in an emergency such as a vehicle collision, and can control the retraction amount of the webbing. Here, as an actuator used for controlling the retraction amount of webbing in a webbing retractor, for example, as disclosed in Patent Document 1 below, a gas generator 114 that pushes out a pressing plunger 118 (a piston member) can be mentioned. This gas generator 114 has a bottom portion provided with a hole into which the pressing plunger 118 is slidably fitted or loosely inserted, and an open end portion covering a portion where working gas is generated, and includes a bottomed cylindrical member inside which the pressing plunger 118 is pushed out to the outside by working gas generated when the gas generating portion is activated. [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2007-84042 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] In the above Patent Document 1, the piston member can be easily pushed out by the operation of the actuator. However, in recent years, at least the portion to which the actuator is attached in a seat belt retractor is sometimes made of resin or the like. When attaching the above actuator to this seat belt retractor, it is necessary to prevent the seat belt retractor from being damaged due to expansion or breakage of the bottomed cylindrical member of the actuator during operation.

[0005] Therefore, the present invention aims to provide an actuator having a bottomed cylindrical member that can be easily manufactured and is configured so as not to damage the seat belt retractor during operation. [Means for solving the problem]

[0006] (1) The present invention comprises a gas generating unit that generates an operating gas that pushes out a piston member by igniting or burning a chemical agent; a bottom portion provided with a hole into which the piston member is slidably fitted or loosely inserted; and an open end portion that covers at least the portion of the gas generating unit that generates the operating gas, wherein the piston member is pushed out to the outside by the operating gas generated when the gas generating unit is in operation, and the bottom portion of the bottom cylindrical member is provided with a fragile portion that ruptures when the internal pressure of the bottom cylindrical member exceeds a predetermined value during operation.

[0007] (2) The vulnerable portion in the actuator described in (1) above is preferably one or more recesses formed around the hole.

[0008] (3) The recess in the actuator described in (2) above is preferably groove-shaped.

[0009] With the above configuration, even if the internal pressure of the bottomed cylindrical member exceeds a predetermined value (for example, a pressure value that would deform or damage the cylindrical portion) during operation, the weak point will rupture, allowing the internal pressure of the bottomed cylindrical member to be appropriately adjusted and the pressure on the cylindrical portion of the bottomed cylindrical member to be suppressed. In other words, even when the actuator according to the present invention is operated in a manner in which the cylindrical portion of the bottomed cylindrical member is mounted in contact with a resin retractor or the like, the cylindrical portion of the bottomed cylindrical member will not expand or deform to such an extent that it could deform the retractor, thus preventing damage to the retractor-side component. Furthermore, the actuator according to the present invention can push outward a piston member that is fitted or loosely inserted into a hole provided at the bottom of the bottomed cylindrical member. In other words, it can be used as an actuator that presses against, for example, a load limiter on the retractor side via the piston member. [Brief explanation of the drawing]

[0010] [Figure 1] This figure shows an actuator according to an embodiment of the present invention, where (a) is a view from one end (piston member not shown) and (b) is a cross-sectional view (piston member shown). [Figure 2] (a) is a cross-sectional view showing the initial state of the actuator in Figure 1, and (b) is a cross-sectional view showing the state of the actuator in Figure 1 after the depressurization operation. [Figure 3] This figure shows an actuator according to a modified embodiment of the present invention. [Modes for carrying out the invention]

[0011] Hereinafter, an actuator according to an embodiment of the present invention will be described with reference to the drawings.

[0012] As shown in Figure 1, the actuator 100 of this embodiment comprises a bottomed cylindrical member 10 and a holder 40 that holds (locks) the bottomed cylindrical member 10 and the igniter 30. As shown in Figure 2, the actuator 100 is positioned inside a housing hole 51 provided in the base 50 of a retractor (not shown) and is fixed to the base 50 by fastening means such as bolts (not shown).

[0013] The bottomed cylindrical member 10 is a bottomed cylindrical member having an opening at one end, and comprises a bottom portion 11, a cylindrical portion 12, a hole portion 13, a flange portion 14, and an open end portion 15. The bottom portion 11 is provided at the other end of the bottomed cylindrical member 10, and a hole portion 13 is formed in the center of it. As shown in Figure 2(a), the other end of the piston member 60 is slidably fitted or loosely inserted into the hole portion 13. Note that by one end of the piston member 60 (not shown) contacting (pressing) a predetermined location on the load limiter (not shown) provided on the retractor, the load limiter can be activated. Here, a load limiter is a device that, when a certain load is applied to the seat belt during a car collision, gradually loosens the restraint of the seat belt to prevent further load, thereby reducing the load on the occupant's body.

[0014] Furthermore, as shown in Figure 1(a), multiple groove-shaped scores 17 (weak points) are formed around the hole 13 in the bottom portion 11 at equal angles with respect to the center of the hole 13 and along the radial direction from the center of the hole 13. The flange portion 14 is crimped and fixed to the holder 40 by the outer end portion 44, which will be described later. The open end portion 15 covers the cap member 31 side, which will be described later, and is the part where the flame (working gas) of the igniter 30 is generated.

[0015] The igniter 30 comprises a cap member 31 that covers an ignition part (not shown) capable of igniting the contained agent, and a pair of terminal pins 32 connected to the ignition part to which a predetermined amount of current is supplied. The igniter 30 is activated when a collision is detected by a collision detection means (not shown) provided in the vehicle when the vehicle collides, and based on this, current is supplied to the ignition part via the terminal pins 32 from a control unit provided in the vehicle. The "agent" includes an igniter and / or a gas generating agent. In this embodiment, a gas generating agent is not used, but if necessary, the gas generating agent may be housed inside the bottomed cylindrical member 10.

[0016] Furthermore, the igniter 30 (an example of a gas generating unit) is fixed in such a state that the central axis of the igniter 30 and the central axis of the holder 40 are approximately aligned, with a pair of terminal pins 32 inserted through a pair of holes (not shown) formed approximately in the center of the holder 40.

[0017] The holder 40 is a roughly cylindrical, integrally molded metal part comprising a female connector portion 41, a hole portion 43, and an outer end portion 44. The female connector portion 41 is a part for receiving the male connector portion (not shown) of a harness for connecting the igniter 30 and the control unit (not shown) together with the ring 20. The ring 20 can be selected as either having a short-circuit function or not having a short-circuit function, depending on the requirements. The outer end portion 44 is roughly cylindrical before the flange portion 14 is crimped and fixed, and deforms when pressed during crimping and fixing. The hole portion 43 is formed in the approximate center of the holder 40 so that the igniter 30 can be fitted into it.

[0018] Next, the operation of the actuator 100, which has the above-described configuration and is attached to the retractor, under normal conditions (when the internal pressure of the bottomed cylindrical member 10 during operation is less than a predetermined value and the cylindrical portion 12 of the bottomed cylindrical member 10 is not affected by the internal pressure) will be described. For example, the actuator 100 in its initial state is as shown in Figure 2(a), but when the actuator is activated due to a collision with a car, the igniter 30 is activated and the ignition powder burns, generating thermal energy into the space 16. At this time, the other end of the piston member 60 receives a pressure wave along with the thermal energy, and the piston member 60 is pushed toward the load limiter (not shown) side (towards one end of the piston member 60). Then, the load limiter, which is pressed by one end of the piston member 60 inside the retractor, is activated, and when a certain load is applied to the seat belt, the restraint of the seat belt is gradually loosened to prevent further load, thereby reducing the load on the occupant's body.

[0019] Next, we will describe the operation of the actuator 100, which has the above-described configuration and is attached to the retractor, when the internal pressure of the closed-bottom cylindrical member 10 exceeds a predetermined value during operation (when the pressure value is such that the cylindrical portion 12 of the closed-bottom cylindrical member 10 may expand, deform or break to such an extent that the retractor may deform). For example, the flame (working gas) generated by the igniter 30 that is activated during a car collision is emitted into the space 16. When the internal pressure of the closed-bottom cylindrical member 10 exceeds a predetermined value, the score 17 ruptures as shown in Figure 2(b), so the internal pressure of the closed-bottom cylindrical member 10 is reduced. Therefore, the cylindrical portion 12 of the closed-bottom cylindrical member 10 does not expand, deform or break. Also, as shown in Figure 2(b), the score 17 becomes the broken portion 17A after rupture, and the hole 13 becomes the end portion 13A. Furthermore, the other end of the piston member 60 is subjected to a pressure wave along with the flame, pushing the piston member 60 toward the load limiter (not shown) (in the direction of one end of the piston member 60). Then, the load limiter, pressed by one end of the piston member 60 within the retractor, activates, and when a certain load is applied to the seat belt, it gradually loosens the restraint of the seat belt to prevent further load, thereby reducing the load on the occupant's body.

[0020] According to this embodiment, even if the internal pressure of the bottomed cylindrical member 10 exceeds a predetermined value during operation (for example, a pressure value that deforms or damages the cylindrical portion 12), the score 17, which is a fragile portion, will cleave. Therefore, the internal pressure of the bottomed cylindrical member 10 can be appropriately adjusted, and the pressurization applied to the cylindrical portion 12 of the bottomed cylindrical member 10 can be suppressed. That is, as shown in FIG. 2, even when the actuator 100 operates after being installed such that the cylindrical portion 12 of the bottomed cylindrical member 10 is in contact with a resin-made retractor or the like, the cylindrical portion 12 of the bottomed cylindrical member 10 will not undergo expansion deformation to an extent that can deform the retractor, nor will it be damaged. Therefore, members on the retractor side will not be damaged.

[0021] Furthermore, according to this embodiment, the piston member 60 that is fitted or loosely inserted into the hole 13 provided in the bottom 11 of the bottomed cylindrical member 10 can be pushed outward (to the right in the drawing sheet of FIG. 2). That is, the present invention can be used via the piston member 60 as an actuating device that presses against, for example, a load limiter on the retractor side.

[0022] The embodiments of the present invention have been described above with reference to the drawings. However, it should be understood that the specific configuration is not limited to these embodiments. The scope of the present invention is defined by the claims rather than the above description of the embodiments, and includes all modifications within the meaning and scope equivalent to the claims.

[0023] For example, instead of the score 17 described above, fragile portions of various shapes may be adopted, such as a fragile portion 117 in the form of a recess having a thickness that cleaves when the internal pressure reaches or exceeds a predetermined value (see FIG. 3(a)) (the recess may have any shape), or a fragile portion 217 formed in an asterisk-like shape where a plurality of grooves intersect each other (see FIG. 3(b)). In FIG. 3, portions identical to those in the above embodiment are denoted by reference numerals having the same last two digits, and descriptions thereof are omitted. In addition, in this modified example, portions not specifically described are the same as those in the above embodiment, so descriptions thereof are omitted.

[0024] Further, in the above embodiment, six scores 17 are provided at equal angles, but they do not have to be at equal angles, and a configuration in which a number other than six is provided is also acceptable. Further, although each score 17 in the above embodiment is formed radially from the center of the bottom surface 11, it does not have to be formed radially.

[0025] Further, in the above embodiment, an igniter is used as the driving force for sliding the piston member (an example of the gas generating portion), but instead, a gas generator that ignites a gas generating agent with an igniter to generate working gas may be used. Description of Reference Signs

[0026] 10, 110, 210 Bottomed cylindrical member 11, 111, 211 Bottom portion 12, 112, 212 Cylindrical portion 13, 113, 213 Hole portion 13A End portion 14 Flange portion 15 Open end portion 16 Space 17 Score (fragile portion) 117, 217 Fragile portion 17A Breaking portion 20 Ring 30 Igniter 31 Cap member 32 Terminal pin 40, 140, 240 Holder 41 Female connector portion 43 Hole portion 44, 144, 244 Outer end portion 50 Base 51 Accommodating hole 60 Piston member 100, 200, 300 Actuator

Claims

1. A gas generating unit that generates an operating gas to push out a piston member by igniting or burning a chemical agent, A bottomed cylindrical member having a bottom portion with a hole into which the piston member is slidably fitted or loosely inserted, and an open end portion that covers at least the portion of the gas generating unit where the working gas is generated, wherein the piston member is pushed out to the outside by the working gas generated when the gas generating unit is operating inside, Equipped with, An actuator characterized in that a weak portion is provided at the bottom of the closed-bottom cylindrical member, which ruptures when the internal pressure of the closed-bottom cylindrical member exceeds a predetermined value during operation.

2. The actuator according to claim 1, characterized in that the weak portion is one or more recesses formed around the hole.

3. The actuator according to claim 2, characterized in that the recess is groove-shaped.

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