JPH0717355A - Safety device for acceleration sensor - Google Patents

Abstract

PURPOSE:To obtain a safety device for an acceleration sensor which is simple in structure, low in cost, absorbs impact force without adding the new members and prevents wrong operation of the acceleration sensor before the installation on a vehicle. CONSTITUTION:An aslant surface 54 is formed at the part in contact with a shaft 50 at the edge part on the counter-driver's side of a sensing mass 52, and an aslant surface 68 which is opposed to the aslant surface 54 is formed at the edge part on the driver's side of the shaft 50. Before the installation on a vehicle, if the shaft 50 is raized to put the aslant surface 68 in contact with the aslant surface 54 of the sensing mass 52, the force R of component which presses the shaft 50 to the side wall of a lower body 44 acts when an inadvertent impact force F1 acts on ths sensing mass 52. Accordingly, a frictional resistance F2 is generated between the shaft 50 and the lower body 44, and a frictional force F3 is generated between the lower body 44 and the sensing mass 52. Since these frictional resistances F2 and F3 act in the direction for suppressing the shift of the sensing mass 52, the operation is suppressed even is case of the inadvertent impact.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention sets a sensing mass, which senses a sudden deceleration of a vehicle or the like and actuates an actuator such as an air bag, to a movement-prevented state at the time of assembling the vehicle body, etc. The present invention relates to a safety device for an acceleration sensor that releases a movement blocking state after the end.

[0002]

2. Description of the Related Art In an air bag system, a gas generating substance enclosed in an inflator is burned to inflate an air bag body when the vehicle is suddenly decelerated. This airbag device has
A built-in acceleration sensor that detects the sudden deceleration of the vehicle, and a safety device is installed to prevent movement of the sensing mass to prevent malfunction due to impact applied before the completion of assembly to the vehicle body such as steering. ing.

As shown in FIG. 10, this safety device has a sensing mass 2 which moves in the direction of arrow A in response to a predetermined acceleration, and a sensing mass 2 which is movable substantially parallel to the sensing mass 2 and advances on the movement locus. A structure having a stopper member 4 movable from a retracted state to a retracted state and a spring 6 for urging the stopper member 4 in a direction opposite to the inertial movement direction (direction A) of the sensing mass 2, The simplest one.

In the safety device having the above structure, the stopper member 4 prevents the sensing mass 2 from moving before the steering wheel or the like is assembled to the vehicle body, and the stopper member 4 is not shown after the assembly is completed. The moving member of the stopper, arrow A
By moving in the direction, the movement blocking state of the sensing mass 2 is released. Therefore, in this movable state of the sensing mass, when the acceleration generated when the vehicle suddenly decelerates is applied to the sensing mass 2, the sensing mass 2 overcomes the damping resistance and the biasing force of the bias spring 7 to move in the inertial movement direction (direction A in the figure). ) To close the electric contact 8 provided on the movement locus of the sensing mass 2, and the airbag device operates.

However, in the above-mentioned safety device, the movement of the sensing mass 2 is blocked only by the biasing force of the spring 6 attached to the stopper member 4, so that an impact force exceeding the biasing force of the spring 6 is applied to the sensing mass 2. In addition, the movement of the sensing mass 2 cannot be prevented and the airbag device malfunctions. Therefore, in order to prevent this, it is necessary to use the spring 6 having a large urging force or to add the movement preventing member 9 as shown in FIG. The movement preventing member 9 is formed of a leaf spring, and the annular bent portion 5 at the tip is interposed between the body 3 and the sensing mass 2 to prevent the sensing mass 2 from being moved accidentally. Further, after the airbag system is assembled, the release device pulls the spring-biased stopper member 4 as shown in FIG. 12, whereby the annular bent portion 5 comes out from between the body 3 and the sensing mass 2. The sensing mass 2 can be moved.

However, if the urging force of the spring 6 is increased, the operating force at the time of release is increased, and in the configuration of FIGS. 11 and 12, the addition of members complicates the structure and causes a cost increase.

[0007]

SUMMARY OF THE INVENTION In consideration of the above-mentioned drawbacks of the prior art, the present invention absorbs impact force without increasing the urging force at the time of release and without adding a new member, and an air bag device or the like. It is an object of the present invention to provide a safety device for an acceleration sensor, which has a simple structure and is capable of preventing the erroneous operation of the.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a sensing mass that moves according to a predetermined acceleration and a state in which the sensing mass is movable from substantially parallel to the sensing mass and is retracted from the state of advancing on the movement locus of the sensing mass. Stopper member that is movable up to and the stopper member in the advanced state and the contact portion between the sensing mass and the moving direction force due to the acceleration of the sensing mass is used as a moving component force in a different direction. And a slope for transmitting to the member.

[0009]

In the advanced state of the stopper member, when an impact force is applied to the sensing mass in the same direction as the inertial movement direction and the sensing mass tries to move, this moving force is transmitted to the stopper member via the slope. Therefore, a component force acts on the stopper member in a direction different from the moving direction for releasing, and as a result, frictional resistance is generated between the body and the stopper member. Since this frictional resistance acts in the direction to prevent the movement of the sensing mass, the stopper member can prevent the sensing mass from moving unintentionally against the large moving force of the sensing mass.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below as an example when applied to an airbag device. FIG. 1 shows an airbag device 10 to which a first embodiment according to the present invention is applied. In the figure, the arrow FR indicates the front of the vehicle.

The airbag device 10 includes an inflator 1
2, cover 14, airbag bag 16 (hereinafter simply referred to as bag 1
6) and the hub 2 of the steering wheel 18
It is attached to a base plate 22 supported by 0. The inflator 12 has a cylindrical shape coaxial with the rotation axis of the steering wheel 18, and one side along the rotation axis of the inflator 12 penetrates the base plate 22 and projects toward the occupant. It is fixed.

The bag body 16 is arranged in a folded state on the occupant side of the base plate 22, and the periphery 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 can be opened from the central portion into a pair of doors and deployed. Has become.

The inflator 12 also contains an enhancer (explosive charge) 30, a detonator 32, a gas generating substance 34, and an acceleration sensor 36. A detonator 32 is arranged substantially in the center of the inflator 12, and an acceleration sensor 36 is arranged on the side opposite to the passenger. The detonator 32 communicates with an acceleration sensor 36 via a guide path (not shown). Further, the enhancer 30 located on the passenger side of the detonator 32 communicates with the detonator 32 via a communication passage (not shown). A gas generating substance 34 is enclosed at symmetrical positions in the inflator 12, and the gas generating substance 34 is communicated with the enhancer 30 via a communication passage (not shown) different from the communication passage. Therefore, at the time of sudden deceleration of the vehicle, the acceleration sensor 36 operates to ignite the detonator 32, and based on the ignition, the enhancer 30 and then the gas generating substance 34 are ignited to generate gas, and the gas is released into the gas hole. It is supplied into the bag body 16 via 40.

As shown in FIG. 3, the acceleration sensor 36 used in the electric ignition type air bag device 90 has a cylindrical upper body 42 and a lower body 44. The lower body 44 is formed with a pair of short projections 46 on opposite sides of the shaft center, and the upper body 42 is formed with a pair of short cutouts 48 corresponding to the pair of short projections 46. , Short protrusion 4 of lower body 44
6, the upper body 42 and the lower body 44 are coaxially coupled to each other.

A substantially cylindrical sensing mass 52 is housed inside the body. In the sensing mass 52, a slope 54 is formed at a portion which is in contact with the shaft 50 at the end portion on the side opposite to the occupant. A compression coil spring 56 is interposed between the end face of the sensing mass 52 on the side opposite to the occupant and the groove 45 formed coaxially inside the lower body 44, and the sensing mass 52 is formed by the compression coil spring 56. It is urged to come into contact with the upper body 42 in a normal state.

A sensing mass 52 is provided inside the lower body 44.
A pair of fixed contacts 58 are attached on the movement locus of, and a moving contact 62 composed of a leaf spring is located on the occupant side, and the moving contact 62 is separated from the fixed contact 58 by the urging force of the leaf spring. . The fixed contact 58 has a wiring 80 as shown in FIG.
Is connected to the detonator 32 (see FIG. 1) and the like via an electric ignition type airbag operation control device 90.

Accordingly, the acceleration sensor 36 has the sensing mass 5
The inertial movement of 2 causes a damping resistance due to the viscosity of the air passing through the clearance between the sensing mass 52 and the body, and this damping resistance causes a small or action time due to vibrations or the like when the vehicle travels on a bad road or the like. If the short acceleration of the sensor acts on the sensing mass 52, it limits the inertial movement of the sensing mass 52. Further, when a large or long-acting acceleration that occurs at the time of sudden deceleration of the vehicle that requires the airbag device 90 to be truly actuated to protect the occupant acts on the sensing mass 52, the sensing mass 52 moves due to inertial movement. The contact 62 is pressed to make contact with the fixed contact 58. Therefore, the circuit is closed, the detonator 32 shown in FIG. 1 is heated and ignited, and the gas generating substance 34 in the inflator 12 is discharged.
Is burned to inflate the bag body 16.

The acceleration sensor 36 has a built-in safety device 64 for selectively controlling the movement blocking state and the movable state of the sensing mass 52 so that the airbag device does not operate before the completion of the vehicle mounting such as steering. Has been done. This safety device 64 has a coil spring 66 as shown in FIG.
And a shaft 50. The shaft 50 has a cylindrical shape and is housed in a groove 49 formed in the side wall of the lower body 44 substantially parallel to the moving direction of the sensing mass 52.
It is possible to move in parallel with the moving direction of. The shaft 50 has an inclined surface 68 corresponding to the inclined surface 54 of the sensing mass 52 at the occupant side end, and the stepped portion 7 is formed at the axially intermediate portion.
0 is formed and one side where the slope 68 is formed is the large diameter portion 7
0A and the other is the small diameter portion 70B. A coil spring 66 is inserted into the small diameter portion 70B to urge the shaft 50 toward the occupant. As shown in FIG. 4, the other end of the coil spring 66 is supported by a stopper 72 fixed to the lower body 44, and the small diameter portion 70B penetrates the stopper 72 and is screwed with the operation arm 74. The operation arm 74 is manually operated by an operator or automatically driven in the direction opposite to the occupant (arrow B direction) to move the shaft 50 in the direction opposite to the occupant.

Next, the operation of this embodiment will be described. When the airbag device 90 is mounted on the vehicle together with the steering wheel 18, the shaft 50 is set in the state shown in FIG. 2 in advance. Therefore, in this state, when the airbag device 90 is carelessly applied to the floor or the like and the impact force F1 is applied to the sensing mass 52 toward the lower body 44 as shown in FIG. 5, the sensing mass 52 will move in the direction of arrow B. And Shaft 50
When the slope 54 of the sensing mass 52 comes into contact with the slope 68, the component force R that presses the shaft 50 against the side wall of the lower body 44 acts. Therefore, a frictional resistance F2 (a component force R multiplied by a friction coefficient) between the shaft 50 and the wall surface of the lower body 44 is generated. A frictional resistance F3 (similar) is also generated between the lower body 44 and the sensing mass 52. As a result, in addition to the urging force F4 of the coil spring 66 itself, the frictional resistance F
2, F3 acts in a direction to prevent the movement of the sensing mass 52, so that inadvertent inflation of the bag body 16 at the time of attachment / detachment to the vehicle body is prevented.

On the other hand, after the base plate 22 is attached to the steering wheel 18, the sensing mass 52 can be moved by pulling down the shaft 50 by the shaft operating arm 74 as shown in FIG. When the vehicle suddenly decelerates, the moving contact 62 comes into contact with the fixed contact 58 due to the inertial movement of the sensing mass 52. When the vehicle is in a sudden deceleration state, the sensing mass 52
Detects a sudden deceleration of the vehicle by moving the vehicle toward the front of the vehicle (direction of arrow B in FIG. 4). The moving contact 62 is pressed by the movement of the sensing mass 52 at this time, and the fixed contact 58 and the moving contact 62 are moved.
And contact each other to close the circuit and burn the gas generating substance 34 in the inflator 12 through the detonator 32. The gas generating substance 34 is decomposed by combustion to release a large amount of gas, and the gas is supplied from the gas holes 40 to the bag body 16 to inflate it. Due to this expansion, the cover 14 is pressed from the inside,
Due to this pressure, the thin portion 29 of the cover 14 is broken and the bag 16
Is interposed between the occupant and the steering wheel 18.

FIG. 6 shows a second embodiment of the present invention. Description of parts having the same structure and operation as those of the first embodiment will be omitted. In this embodiment, the portion of the shaft 50 that contacts the sensing mass 52 is coated with rubber 76, which is an example of a high friction member. Therefore, the component force R generated by the impact force F1 is increased by the rubber 76, and as a result, the frictional resistances F2 and F3 can be increased, and the absorption force against an accidental impact can be increased.

Although the outer circumference of the large diameter portion 70A is coated with the rubber 76 in this embodiment, the material is not limited to rubber and any material having a high frictional force may be used. Instead of coating, the large-diameter portion 70A of the shaft 50 may be entirely made of rubber 76. 7 to 9
Shows a third embodiment of the invention. Description of parts having the same structure and operation as those of the first embodiment will be omitted.

In this embodiment, as shown in FIG. 8, the shaft 50 is provided with a plurality of grooves 77 extending in the longitudinal direction in the direction orthogonal to the moving direction of the shaft 50 at the portion contacting the wall surface of the lower body 44. As shown in FIG. 7, 44 is provided with a ridge 78 capable of engaging with the groove 77 of the shaft 50. Therefore, when the side surface of the shaft 50 comes into contact with the wall surface of the lower body 44 by the impact force F1, the groove 77 and the ridge 78 engage with each other as shown in FIG. As a result, the movement of the shaft 50 is prevented, and as a result, the movement of the sensing mass 52 is prevented, so that it is possible to further increase the absorbing power for impact. It should be noted that, contrary to the above configuration, the shaft 50 may be provided with a ridge and the body may be provided with a groove.

In the first to third embodiments, the sensing mass 52 and the shaft 50 are both provided with slopes, but the same effect can be obtained even if only the shaft 50 or the sensing mass 52 is provided with slopes. Obtainable. In addition, in the present invention, the sensing mass 52 and the shaft 50 may be provided with a friction generating material or a concavo-convex portion for generating a large frictional force with the side wall of the lower body 44, if necessary.

Although the above-mentioned safety device for the acceleration sensor converts the movement of the sensing mass 52 into an electric signal to operate the actuator, it does not convert the moving force of the sensing mass 52 into an electric signal. It can also be applied to a sensor that operates an actuator.

[0026]

As is apparent from the above, the present invention has a simple structure capable of absorbing careless impact force without adding a new member and preventing malfunction of an airbag device or the like. It is possible to obtain an inexpensive safety device for an acceleration sensor.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an airbag device to which a safety device for an acceleration sensor according to an embodiment of the present invention is applied, taken along the vehicle front-rear direction.

FIG. 2 is a cross-sectional view showing a state in which a movement of a sensing mass of a safety device for an acceleration sensor according to a first embodiment of the present invention is blocked, which is cut along a vehicle longitudinal direction.

FIG. 3 is an exploded perspective view of a safety device for an acceleration sensor according to a first embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a movable state of the sensing mass of the safety device for an acceleration sensor according to the first embodiment of the present invention, taken along the vehicle front-rear direction.

FIG. 5 is an operation diagram of FIG. 2 showing an operation of the safety device for an acceleration sensor according to the present invention.

FIG. 6 is a cross-sectional view showing a state in which a movement of a sensing mass of a safety device for an acceleration sensor according to a second embodiment of the present invention is blocked, the sectional view being cut along the vehicle longitudinal direction.

FIG. 7 is a cross-sectional view showing a state in which a movement of a sensing mass of a safety device for an acceleration sensor according to a third embodiment of the present invention is prevented, the state being cut along the vehicle longitudinal direction.

FIG. 8 is a partially enlarged view of the shaft 50 shown in FIG.

FIG. 9 is an operation diagram showing an operation of the safety device for an acceleration sensor according to the third embodiment of the present invention.

FIG. 10 is a cross-sectional view showing a state in which movement of a sensing mass is blocked in the related art and is taken along the vehicle front-rear direction.

11 is a cross-sectional view showing a state in which a movement of a sensing mass is prevented when an impact force absorbing member is added to the safety device for an acceleration sensor in FIG.

12 is an operation diagram showing a movable state of a sensing mass when an impact force absorbing member is added to the safety device for an acceleration sensor of FIG.

[Explanation of Codes] 36 Acceleration Sensor 50 Shaft 52 Sensing Mass 54 Slope 64 Safety Device for Acceleration Sensor 68 Slope

Claims (1)

[Claims] 1. A sensing mass that moves according to a predetermined acceleration, and a stopper member that can move substantially parallel to the sensing mass and that can move from a state of advancing on the movement locus of the sensing mass to a state of withdrawal. And an inclined surface which is provided at the abutting portion between the stopper member in the advanced state and the sensing mass and transmits the moving direction force due to the acceleration of the sensing mass to the stopper member as a moving component force in a different direction. Safety device for acceleration sensor.