JPH0658368U - Acceleration sensor - Google Patents

Abstract

(57) [Abstract] [Purpose] To facilitate the adjustment of damping resistance for decelerating the inertial body. A screw hole 82 is provided in the housing 50, and the base end side of a guide rod 84 is screwed into the screw hole 82 to fix the guide rod 84. Guide rod 84
A guide portion 86 is formed on the tip side of the. The concave portion 90 of the inertial body 52 is tightly fitted to the guide portion 86 of the guide rod 84 so that the inertial body 52 can slide along the axial direction of the guide rod 84. An air chamber 92 whose inner volume fluctuates is formed between the tip side of the guide portion 86 and the bottom side of the recess 90, and an air introduction groove 94 is formed on the outer peripheral surface of the guide portion 86. Therefore, the air after flowing through the air introduction groove 94 passes through the gap of the fitting portion and is sent into the air chamber 92.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an acceleration sensor that includes an inertial body that is inertially moved by an acceleration action, and that activates an occupant protection device when the vehicle suddenly decelerates by a predetermined amount of inertial movement of the inertial body.

[0002]

[Prior art]

 BACKGROUND ART An airbag device is known as a vehicle occupant protection device.

The airbag device is designed to protect the occupant by bulging the bag when the vehicle suddenly decelerates, and an acceleration sensor is used to activate the airbag device when the vehicle suddenly decelerates.

In some acceleration sensors, conventionally, a ball is provided as an inertial body in a cylinder, and when the ball is subjected to acceleration, the ball can inertially move in the cylinder. As a result, at the time of sudden deceleration of the vehicle, the ball inertially moves by a predetermined amount to release the ignition pin, and the ignition pin collides with the detonator and ignites. By the ignition of the detonator, the gas generating substance is burned to generate gas, and the generated gas is supplied into the bag body and the bag body is expanded.

Here, a gap is formed between the inner peripheral surface of the cylinder and the outer peripheral surface of the ball, and when the ball inertially moves, the gap is from front to rear in the inertial moving direction of the ball. Air flows and the air flow creates damping resistance that slows down the ball.

The damping resistance is set to be a predetermined resistance, and when acceleration having a short action time caused by vibration or the like when the vehicle travels on a bad road acts on the ball, Is unable to move inertially carelessly, but it is necessary to truly activate the air bag device to protect the occupant. It can move by inertia.

[0007]

[Problems to be solved by the device]

 By the way, in the above-mentioned conventional acceleration sensor, since the cylinder is located on the outer peripheral side of the ball having a predetermined mass, it is difficult to reduce the size of the acceleration sensor as a whole.

Therefore, a rod-shaped guide rod is fitted in a recess formed in the inertial body, and the inertial body is inertially moved by using the sliding portion between the outer peripheral surface of the guide rod and the recessed portion of the inertial body as a guide. Is being considered. In this structure, air enters the space between the tip side of the guide rod and the bottom side of the recess through the gap of the mating part as it slides, but damping the viscous resistance when passing through this gap. It's resistance.

On the other hand, since the acceleration caused by the type of vehicle to which the acceleration sensor is attached and the location where the acceleration sensor is attached to the vehicle is different, it is necessary to properly adjust the damping resistance for each. In this case, it is possible to reduce the amount of insertion of the guide rod into the inertial body to reduce the fitting range and adjust the damping resistance.However, if the fitting range is too small, the guidance of the inertial body becomes unstable. Therefore, it is necessary to previously form the rod-shaped guide rod and the concave portion of the inertial body to be long, which hinders downsizing of the acceleration sensor.

In view of the above facts, it is an object of the present invention to provide an acceleration sensor which is small in size and facilitates adjustment of a damping resistance for decelerating an inertial body.

[0011]

[Means for Solving the Problems]

 An acceleration sensor according to the present invention includes an inertial body that is guided by a guide material and inertially moves due to the action of acceleration, and the inertial sensor moves a predetermined amount of inertial force to activate a passenger protection device when the vehicle suddenly decelerates. A recess formed in the body for inserting and fitting the guide member and sliding with the guide member during inertial movement of the inertial body; and a front end side of the guide member and a bottom portion of the recess formed in the guide member. The air chamber formed between the side and the side is provided with a passage for circulating air from the outside of the inertial body.

[0012]

[Action]

 When the acceleration acts on the inertial body and the inertial body is guided by the guide material and moves inertially, the inner volume of the air chamber increases or decreases, and along with this, air circulates in the passage, and the guide material Air passes through the gap of the fitting portion between the inertial body and is introduced into the air chamber or discharged from the air chamber.

Although the viscous resistance when air passes through the gap of the fitting portion between the guide member and the inertial body serves as damping resistance for decelerating the inertial body, the length of the passage formed in the guide member is increased. By appropriately setting the height, the length of the fitting portion through which the air passes is changed, and the magnitude of the viscous resistance can be adjusted.

For example, when the type of vehicle to which the acceleration sensor is attached, the mounting position on the vehicle, or the like is changed, a passage having a length set to match the required damping resistance is used as a guide member. Then, the acceleration sensor is assembled using this guide material.

[0015]

【Example】

 An acceleration sensor according to a first embodiment of the present invention is shown in FIGS. 1 to 4, and the present embodiment will be described with reference to these drawings.

FIG. 2 (arrow FR indicates the front of the vehicle) shows an airbag device 10. The airbag device 10 includes an inflator 12, a cover 14, and an airbag bag body 16 (hereinafter, simply referred to as a bag body 16), and is attached to a base plate 22 supported by a hub 20 of the steering wheel 18.

The inflator 12 has a cylindrical shape that is coaxial with the rotation axis of the steering wheel 18, and one side along the rotation axis extends through the base plate 22 and projects toward the occupant side. It is fixed through 24.

The bag body 16 is arranged in a folded state on the occupant side of the base plate 22, and the peripheral edge of the opening 26 is fixed to the base plate 22 by a mounting ring 28. The one side of the inflator 12 is inserted into the bag body 16, and a gas hole 40 of the inflator 12 is opened facing the inside of the bag body 16.

The cover 14 is formed in a bowl shape, and an opening edge thereof is fixed to the base plate 22 so as to store the bag body 16 between the cover 14 and the base plate 22. A thin portion 29 is formed on the bottom wall of the cover 14 facing the occupant, and when the bag body 16 is inflated, the thin portion 29 is broken and the cover 14 is opened from the center portion into a pair of doors and deployed. It is possible.

In addition, the inflator 12 houses an enhancer 30, a detonator 32, a gas generating substance 34, and an acceleration sensor 36. When the vehicle suddenly decelerates, the ignition pin 38 on the acceleration sensor 36 side collides with the detonator 32 and the detonator 32. Is ignited, the gas generating substance 34 is ignited based on the ignition, and gas is generated, and the gas is supplied into the bag body 16 through the gas holes 40.

Here, the acceleration sensor 36 will be described in detail. As shown in FIG. 1, a screw hole 82 is provided on the upper wall surface of the housing 50 forming the outer frame of the acceleration sensor 36, and a guide rod 84 as a guide member is fixed to the screw hole 82. ing. That is, in the guide rod 84, the male screw 88 is coaxially projected from the guide portion 86, the male screw 88 is screwed into the screw hole 82 to fix the guide rod 84, and the guide portion 86 is inserted into the recess 60 in the housing 50. It stands out.

On the other hand, in the recess 60, an inertial body 52 having a cylindrical shape and having a predetermined mass is located. Further, the base of the inertial body 52 contacts the bottom surface 61 of the recess 60 to prevent the movement of the inertial body 52 toward the rear of the vehicle.

The inertial body 52 has a circular cross section and has a concave portion 90 formed so that the inner peripheral surface thereof extends linearly along the axial direction. The concave portion 90 is formed inside the guide rod 84. The inertia member 52 can slide along the axial direction of the guide rod 84 by being tightly fitted with the guide rod 86. This allows the inertial body 52 to move along the vehicle front-rear direction.

An air chamber 92 whose inner volume fluctuates due to the sliding of the inertia body 52 with respect to the guide portion 86 is formed between the tip side of the guide portion 86 and the bottom side of the recess 90. As shown in FIGS. 1 and 4, an air introduction groove 94, which is a passage extending in the axial direction of the guide portion 86, is formed on the outer peripheral surface of the guide portion 86, and when the air chamber 92 becomes a negative pressure, the inertial member 52 is released. The air after flowing through the air introduction groove 94 from the outside passes through the gap of the fitting portion between the outer peripheral surface of the guide rod 84 and the inner wall surface of the recess 90 and is sent into the air chamber 92. There is.

Therefore, when acceleration acts on the inertial body 52, the inertial body 52 inertially moves forward of the vehicle from the position where the contact is blocked as shown in FIG. 1, and the air chamber 92 expands in accordance with this inertial movement. As a result, air passes through the gaps in the air introducing groove 94 and the fitting portion between the outer peripheral surface of the guide rod 84 and the inner wall surface of the recess 90, and the air flows into the air chamber 92 whose pressure is lowered. Become. At this time, air receives viscous resistance from the outer peripheral surface of the guide rod 84 and the inner wall surface of the recess 90, and it becomes difficult for air to enter the air chamber 92, and the amount of movement of the inertial body 52 is reduced.

In the housing 50, the ignition pin 38, the lever 64, the rotating body 76, etc. are provided. The ignition pin 38 is arranged so that its longitudinal direction is parallel to the moving direction of the inertial body 52 along a moving path 70 formed through the housing 50. From the non-starting position where the vehicle rear end of the ignition pin 38 is located in the housing 50, the vehicle rear end of the ignition pin 38 comes out of the housing 50 and comes into contact with the detonator 34 (see FIG. 2) to ignite the detonator 34. The ignition pin 38 can be moved to a starting position where the airbag device 10 is started up.

An engaging collar 72 is provided at an intermediate portion of the ignition pin 38, and a coil spring 74 is interposed between the engaging collar 72 and the housing 50. The coil spring 74 constantly urges the ignition pin 38 to move toward the starting position.

Further, a cylindrical rotating body 76 is provided corresponding to the engaging flange 72, and the engaging flange 72 is normally locked to the outer peripheral surface of the rotating body 76. Further, the support shafts 66 formed so as to project from both ends of the rotating body 76 are supported by bearings (not shown) on the housing 50 side, and the rotation center line along the direction orthogonal to the inertial movement direction of the inertial body 52 is formed. The rotating body 76 is rotatable around.

As shown in FIGS. 1 and 3, the rotating body 76 is formed with a trigger portion 80 that is cut out in a semi-cylindrical shape in the middle portion thereof, and as the rotating body 76 rotates, When the engaging collar 72 and the trigger portion 80 face each other, the engagement of the outer peripheral surface of the rotating body 76 with respect to the engaging collar 72 is released.

A base end portion of a lever 64, which is long in a direction orthogonal to the inertial movement direction of the inertial body 52, is fixed to one end portion of the rotating body 76. The tip of the lever 64 extends to the front surface of the inertial body 52 in the inertial movement direction, and the upper side of the tip of the lever 64 contacts the front surface of the inertial body 52 in the movement direction in FIG. The top of the pin 56 pressed by the coil spring 68 interposed between the pin and the housing 50 is in contact with the lower side of the part.

Therefore, the lever 64 is rotationally biased by the coil spring 68 so that the tip of the lever 64 always presses the inertial body 52 rearward of the vehicle. When the inertial body 52 inertially moves forward of the vehicle against the biasing force of the coil spring 68, the lever 64 is rotated counterclockwise in FIG. 1, and the rotating body 76 integrated with the lever 64 is rotated. It is rotated.

As described above, normally, the ignition pin 38 is held in the non-starting position (the state of FIG. 1), but when the vehicle is rapidly decelerated, the inertial body 52 is accelerated and the inertial body 52 inertially moves by a predetermined amount. . Along with this, the inertial body 52 rotates the lever 64, and by the rotation of the lever 64, the engagement of the outer peripheral surface of the rotating body 76 with respect to the engaging flange 72 is released, and the ignition pin 38 is moved to the starting position. Movement is allowed.

With this release, the ignition pin 38 moves toward and contacts the detonator 32 based on the biasing force of the coil spring 74, and the detonator 32 is ignited. The ignition of the detonator 32 burns the gas generating substance 34 to generate gas, and the generated gas is supplied into the bag body 16 to bulge the bag body 16.

Next, the operation of this embodiment will be described. In normal vehicle operation, the acceleration acting on the inertial body 52 is small, and in this case, the inertial body 52 cannot counter the biasing force of the coil spring 68, and the inertial movement of the inertial body 52 is restricted. . Further, even if the inertial body 52 moves a little amount against the biasing force of the coil spring 68, the inside of the air chamber 92 becomes a negative pressure. Produce an effect.

Then, the damping resistance is set to be a predetermined resistance. That is, the guide length L, which is the length of the entire fitting portion shown in FIG. 1, is constant, but the length L1 of the fitting portion where air passes and damping resistance is equal to the length L2 of the air introducing groove 94. The damping resistance is determined as a result of determining the length L2 of the air introduction groove 94.

From the above, when the acceleration sensor 36 is assembled, if the length L 2 of the air introduction groove 94 is processed in advance to a proper length, the damping resistance becomes a predetermined resistance and the ignition pin The value of the acceleration that activates 38 can be set arbitrarily. Therefore, when the acceleration acting on the inertial body 52 is short due to the vibration or the like when the vehicle travels on a bad road, the inertial body 52 loses a predetermined amount of inertial movement due to the damping resistance. Therefore, the airbag device 10 is not activated while the ignition pin 38 is held in the non-activated position.

On the other hand, when a predetermined acceleration acts on the inertial body 52 for a long time when the vehicle suddenly decelerates to activate the airbag device 10, the inertial body 52 overcomes the damping resistance generated by the inertial movement and exceeds a predetermined amount. Inertia moves. Then, the movement of the ignition pin 38 to the activation position is permitted, and the airbag device 10 is activated.

Here, for example, when the type of vehicle to which the acceleration sensor 36 is attached, the attachment portion to the vehicle, or the like is changed, the length L2 of the air introducing groove 94 is set when the air introducing groove 94 is processed. By changing the length, the length L 1 of the fitting portion where the damping resistance is generated is changed, and as a result, the viscous resistance is increased or decreased to be adjusted to an appropriate damping resistance.

Next, a guide rod of the acceleration sensor according to the second embodiment of the present invention is shown in FIGS. 5 and 6, and the present embodiment will be described based on these drawings.

As shown in FIG. 5, in this embodiment, the chamfered portion 102 extending along the axial direction of the guide rod 84 is formed on the outer peripheral surface of the guide portion 86 of the guide rod 84. Becomes a passage for circulating air. The angle α of the chamfered portion 102 is sufficiently large, for example, about 15 ° to 20 ° in FIG.

From the above, the damping resistance can be adjusted by appropriately setting the length of the chamfered portion 102 along the axial direction of the guide rod 84.

Next, a guide rod of an acceleration sensor according to a third embodiment of the present invention is shown in FIG. 7, and this embodiment will be described based on this drawing.

As shown in FIG. 7, in the present embodiment, a plurality of grooves 104 extending along the axial direction of the guide rod 84 are formed on the outer peripheral surface of the guide portion 86 of the guide rod 84, so that the guide portion 86 is formed. The portion near the male screw 88 has a spline shape. Then, the plurality of grooves 104 serve as passages through which air flows.

As described above, the damping resistance can be adjusted by appropriately setting the length of the plurality of grooves 104 along the axial direction of the guide rod 84.

Next, a guide rod of an acceleration sensor according to a fourth embodiment of the present invention is shown in FIG. 8, and this embodiment will be described based on this drawing.

As shown in FIG. 8, in the present embodiment, a through hole 106 is formed inside the guide rod 84, and this through hole 106 serves as a passage for passing air.

As described above, the damping resistance can be adjusted by appropriately setting the length of the through hole 106 along the axial direction of the guide rod 84.

The other configurations of the second, third, and fourth embodiments are the same as those of the first embodiment, and therefore, the same effects as the first embodiment can be obtained. .

Further, in the first embodiment, the positional relationship between the inertial body 52 and the guide rod 84 is such that the inertial body 52 is in the direction of coming out of the guide rod 84 at the time of sudden vehicle deceleration. Conversely, the inertial body 52 may be inserted deeper into the guide rod 84 when the vehicle is rapidly decelerated. In this case, the air chamber 92 shrinks and air is discharged from the air chamber 92 when the vehicle decelerates rapidly. Even in such a structure, the air introduction groove 94, the chamfered portion 102, the groove 104, the through hole 106, and the like are formed. It goes without saying that the passage allows the air to flow therethrough and has the same effect as that of the first embodiment.

Further, the present invention is not limited to the above embodiments, but various modifications can be made. For example, in each of the above embodiments, the occupant protection device is the airbag device 10. However, the occupant protection device is not limited to this. Of course, it can also be applied to start up the preloader for mounting on the.

[0051]

[Effect of device]

 The acceleration sensor according to the present invention has an excellent effect that the damping resistance for decelerating the inertial body can be easily adjusted while being small in size.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an acceleration sensor according to a first embodiment of the present invention taken along the vehicle longitudinal direction.

FIG. 2 is a cross-sectional view taken along the vehicle front-rear direction of an airbag device to which the acceleration sensor according to the first embodiment of the present invention is applied.

FIG. 3 is a perspective view showing a rotating body, a lever, an ignition pin and the like of the acceleration sensor according to the first embodiment of the present invention.

FIG. 4 is a perspective view showing a guide rod of the acceleration sensor according to the first embodiment of the present invention.

FIG. 5 is a perspective view showing a guide rod of an acceleration sensor according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a guide rod of an acceleration sensor according to a second embodiment of the present invention.

FIG. 7 is a perspective view showing a guide rod of an acceleration sensor according to a third embodiment of the present invention.

FIG. 8 is an enlarged sectional view of an essential part of an acceleration sensor according to a fourth embodiment of the present invention.

[Explanation of symbols]

 10 Airbag device (occupant protection device) 36 Acceleration sensor 52 Inertial body 84 Guide rod (guide member) 86 Guide portion 90 Recessed portion 92 Air chamber 94 Air introduction groove (passage) 102 Chamfered portion (passage) 104 Groove (passage) 106 Penetration Hole (passage)

Claims (1)

[Scope of utility model registration request] 1. An acceleration sensor, comprising an inertial body which is guided by a guide member and inertially moves by the action of acceleration, and which activates an occupant protection device when the vehicle suddenly decelerates by a predetermined amount of inertial movement of the inertial body. A concave portion that is formed for insertion and fitting of the guide member and that slides with the guide member during inertial movement of the inertial body, and between the tip side of the guide member and the bottom side of the concave portion formed in the guide member. An acceleration sensor, characterized in that a passage through which air flows from the outside of the inertial body is provided in the air chamber formed in the.