JP2000131157A - Pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect external forces of different magnitude using one sensor. SOLUTION: The pressure sensor 4 comprises a first switch section 28 having a pair of opposite conductive members 32, 32, and a second switch section 30 having a pair of opposite conductive members 34, 34 disposed in an elongated casing 20 made of an insulating elastic material such that the external forces being detected respectively are aligned each other. Deformation of the casing 20 when the first switch section 28 is conducting is set smaller than that when the second switch section 30 is conducting. Consequently, small deformation of the casing 20 caused by an external force can be detected at the first switch section 28 and large deformation of the casing 20 can be detected at the second switch section 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor and, more particularly, to a pressure sensor having a first switch and a second switch provided in a casing.

[0002]

2. Description of the Related Art When a car crashes, it is necessary to protect a person in the car from the impact of the collision. In view of this, there has been conventionally known a pressure sensor that detects a stress acting on an automobile at the time of a collision and activates an airbag in a front bumper (for example, US Pat.
106137).

[0003] In recent years, it has been legally regulated not only to protect a person in a vehicle at the time of a collision but also to protect a pedestrian who has collided with a car, and to detect an impact when a pedestrian collides with a car. Therefore, it is necessary to take some measures to protect pedestrians.

[0004]

However, the conventional pressure-sensitive sensor detects an extremely large external stress acting on the automobile when it collides with a wall or the like. May not be possible.

[0005]

According to a first aspect of the present invention, there is provided an elongated casing made of an insulating elastic material, in which conductive members facing each other at a predetermined interval are provided.
In a pressure-sensitive sensor arranged along the longitudinal direction of the casing, a first sensor having a pair of opposing conductive members is provided.
A switch portion and a second switch portion having a pair of conductive members opposed to each other are provided in the casing so that the directions of the external forces to be detected match each other, and the first switch portion is in an energized state. The amount of deformation of the casing at the time of is set to be smaller than the amount of deformation of the casing at the time when the second switch section is energized. Accordingly, the pressure-sensitive sensor detects small deformation of the casing caused by the external force by the first switch unit, and detects large deformation of the casing by the second switch.
It can be detected by the switch.

According to a second aspect of the present invention, in the first aspect, one conductive member of the first switch portion is shared as one conductive member of the second switch portion. It is characterized by having. Thus, the first switch unit and the second switch unit share the conductive member, and the configuration of the pressure-sensitive sensor is simplified.

According to a third aspect of the present invention, in the first or the second aspect of the present invention, a state in which the pair of conductive members of the first switch unit are energized mutually is built in the front bumper of the automobile. The condition for operating the pedestrian protection device is that the state in which the conductive members of the first switch portion and the second switch portion are energized is the operation condition of the occupant protection device. As a result, it is possible to control the pedestrian protection device and the occupant protection device having different operating conditions.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a front bumper 2 of an automobile. A long pressure-sensitive sensor 4 is built in the front bumper 2 along the width of the vehicle body.

The front bumper 2 includes a reinforcement frame 6 having a substantially rectangular cross section attached to the vehicle body, and a bumper fascia 8 having a substantially U-shaped cross section which is fitted to the reinforcement frame 6 and projects toward the front of the vehicle body. A hollow portion 12 having a substantially rectangular cross section is defined by the front wall surface 10 of the vehicle body of the reinforcing frame 6 and the bumper fascia 8 along the width direction of the vehicle body.

A pad 14 having a substantially rectangular cross section which fills the cavity 12 is attached to the front wall surface 10 of the vehicle body of the reinforcing frame 6 with a double-sided tape. This pad 1
A recess 16 is formed in the mounting surface of the vehicle body 4 on the vehicle body front wall surface 10 along the vehicle body width direction.

The pressure sensor 4 is accommodated in the recess 16. Then, a bottom wall 18 of the pressure-sensitive sensor 4 described later is fixed to the front wall surface 10 of the vehicle body by an adhesive means such as a double-sided tape.

The pressure sensor 4 is, as shown in FIG.
It has a hollow casing 20 made of insulating silicon rubber. The casing 20 has a bottom wall 18 and a distal end wall 22 facing each other connected by a pair of side walls 24, 24, and is formed in a substantially trapezoidal cross section. The inside of the casing 20 is divided by the inner wall 26 over the entire length of the casing 20 in the longitudinal direction, and is divided into a first switch portion 28 and a second switch portion 30.

The inner wall 26 is substantially parallel to the tip wall 22 and the bottom wall 18, and both ends are connected to the pair of side walls 24, 24, respectively.

The first switch section 28 is connected to the end wall 2.
2 and a pair of conductive members 3 disposed on the inner wall 26.
2,32. The pair of conductive members 32, 32
Is made of conductive silicon rubber and has a substantially flat plate shape.
The casing 20 is opposed to each other while being spaced apart from each other, and is disposed over the entire length of the casing 20 in the longitudinal direction.

The second switch section 30 has a pair of conductive members 34, 34 disposed on the inner wall 26 and the bottom wall 18. The pair of conductive members 34, 3
Numeral 4 is made of conductive silicone rubber, has a substantially flat plate shape, is spaced apart from each other and faces each other.
0 over the entire length in the longitudinal direction.

A pair of side walls 24, 2 of the casing 20
4 is formed such that the wall thickness of the first switch portion 28 is thinner than the wall thickness of the second switch portion 30 from the portion where the internal wall 26 is connected.

That is, the amount of deformation of the casing 20 when the first switch portion 28 is energized with respect to an external force acting on the distal end wall 22 in the direction of the arrow in FIG.
It is set smaller than the amount of deformation of the casing 20 when the second switch section 30 is energized. That is, the first switch unit 28 is energized by a small external stress, whereas the second switch unit 30 is energized by a relatively large external stress.

The pressure-sensitive switch 4 includes the casing 20, the inner wall 26, and the first switch unit 2.
8, a pair of conductive members 32, 32
A pair of conductive members 34 and 3 disposed in the switch unit 30 of FIG.
And 4 are integrally formed by extrusion.

The operation of the pedestrian protection device for safely protecting a pedestrian colliding with the vehicle and the occupant protection device for safely protecting persons in the vehicle when the vehicle collides, using the pressure-sensitive sensor 4 described above. Is controlled. More specifically, the energized state of the first switch unit 28 is an operation condition of the pedestrian protection device, and the energized state of the first switch unit 28 and the second
The energized state of the switch unit 30 is an operating condition of the occupant protection device. In addition, operating conditions of the pedestrian protection device and the occupant protection device include parameters related to driving conditions such as speed and acceleration.

As shown in FIGS. 3 and 4, when a pedestrian collides with the front bumper 2 during traveling, the casing 20 of the pressure-sensitive sensor 4 is deformed due to the compression deformation of the front bumper 2 and the first The switch unit 28 is turned on, and a signal is sent to the control box 36. Then, the pedestrian protection device operates according to a command from the control box 36. This pedestrian protection device is, for example, as shown in FIG.
The airbag 40 is deployed upward to protect a pedestrian thrown onto the hood 38 by the collision.

When the collision between the pedestrian and the front bumper 2 is severe, the second switch section 30 is also energized, and this signal is transmitted to the control box 36. Then, in response to a command from the control box 36, the occupant protection device operates and the in-vehicle airbag 42 is deployed.

Also, when the driver is parked away from the car,
When something hits the front bumper 2 and the first switch section 28 or the first switch section 28 and the second switch section 30 are energized, the condition that the vehicle speed is equal to or higher than a predetermined set value is a pedestrian protection condition. The pedestrian protection device and the occupant protection device do not operate because they are added to the operating conditions of the device and the occupant protection device.

As described above, the pressure-sensitive sensor 4 has the first switch portion 28 and the second switch portion 30 which are sequentially energized by external stresses of different magnitudes. The protection device and the occupant protection device can be controlled, and the first switch unit 28 or the second switch unit can be controlled by using the pressure-sensitive sensor 4 and parameters representing the driving state of the vehicle such as speed and acceleration. Even when the unit 30 is in the energized state, the pedestrian protection device and the occupant protection device can not be operated depending on the situation, and control with less malfunction can be performed.

The amount of deformation of the front bumper 2 caused by external stress is determined by the first switch unit 28 and the second switch unit 3.
Since it can be sensed stepwise by 0, even when the pedestrian protection device and the occupant protection device are not activated,
When the first switch section 28 or the second switch section 30 is in the energized state, the driver can be notified by a warning lamp or the like.

The distance between the pair of conductive members 32 of the first switch unit 28 and the distance between the second switch unit 3
The distance between the pair of conductive members 34, 34 is the size of the casing 20 and the pair of side walls 2 of the inner wall 26.
Since it can be set by appropriately changing the connection position with respect to the pedestrian protection device and the occupant protection device, the magnitude of the external stress that activates the pedestrian protection device and the occupant protection device, that is, the operating conditions of the pedestrian protection device and the occupant protection device can be arbitrarily set Can be set.

Since the pressure-sensitive sensor 4 is integrally formed by extrusion molding, the pressure-sensitive switch 4 can be reduced in size.

Further, the deformation speed of the pressure-sensitive sensor 4 is different between a case where the front bumper 2 collides with a wall or the like while the vehicle is running at a low speed and a case where the front bumper 2 collides with the vehicle while traveling. The second after the section 28 has been turned on
There is a difference in the time until the switch unit 30 is turned on. Therefore, the operation of the occupant protection device is controlled by adding the time from when the first switch unit 28 is energized to when the second switch unit 30 is energized to the operation condition of the occupant protection device. Can also.

FIG. 5 shows a pressure-sensitive sensor 50 according to a second embodiment.

The pressure-sensitive sensor 50 has a hollow elongated casing 52 made of insulating silicon rubber.
The casing 52 has a bottom wall 54 and a front end wall 56 facing each other connected by a pair of side walls 58, 58, and has a substantially trapezoidal cross section.

The inside of the casing 52 is divided by a conductive member 60 serving as a cathode over the entire length of the casing 52 in the longitudinal direction, and is divided into a first switch portion 62 and a second switch portion 64.

The first switch section 62 is composed of a pair of conductive members 60 and 6 composed of the conductive member 60 serving as a cathode and the conductive member 66 serving as an anode disposed on the end wall 56.
6. The second switch section 64 includes a pair of conductive members 60 including the conductive member 60 serving as a cathode and the conductive member 68 serving as an anode disposed on the bottom wall 54.
68.

Each of the conductive members 60, 66, and 68 is made of conductive silicon rubber, has a substantially flat shape, and is disposed over the entire length of the casing 52 in the longitudinal direction.

The pair of side walls 58, 58 of the casing 52 have a thickness on the side of the first switch portion 62 on the side of the portion where the conductive member 60 serving as a cathode is connected. It is formed thinner than the thickness of the portion 64 side.

That is, the amount of deformation of the casing 52 when the first switch portion 62 is energized with respect to an external force acting on the distal end wall 56 in the direction of the arrow in FIG.
It is set smaller than the amount of deformation of the casing 52 when the second switch 64 is energized. That is, the first switch section 62 is energized by a small external stress, whereas the second switch section 64 is energized by a relatively large external stress.

The pressure-sensitive switch 50 includes the casing 52, the conductive member 60 serving as a cathode, the conductive member 66 disposed on the front end wall 56, and the bottom wall 54.
Are integrally formed with the conductive member 68 by extrusion molding.

In the second embodiment, since the first switch section 62 and the second switch section 64 share the conductive member 60, the pressure-sensitive sensor 5 is different from the first embodiment.
0 can be simplified, and the pressure-sensitive sensor 50 can be downsized.

FIG. 6 shows a third embodiment of the pressure-sensitive sensor 70.

This pressure-sensitive sensor 70 has a hollow elongated casing 72 made of insulating silicon rubber. The casing 72 has a bottom wall 74 and a front end wall 76 which are opposed to each other and are connected by a substantially flat side wall 78 and a side wall 80 bent in a step shape, and are formed to have a substantially L-shaped cross section. .

The side wall 80 includes an intermediate portion 82 substantially parallel to the bottom wall 74 and the front end wall 76, and an upper bent portion 81 bent upward from the intermediate portion 82 and connected to the front end wall 76. , The bottom wall 7 is bent downward from the intermediate portion 82.
4 is connected to the lower bent portion 83.

The interior of the casing 72 is
2 and the upper bent portion 81, which extends horizontally from the bent portion, is divided by the inner wall 84 connected to the side wall 78 over the entire length of the casing 72 in the longitudinal direction, and is divided toward the tip wall 76. A first switch section 86 is defined.
Furthermore, the casing 72 extends downward from the bent portion between the intermediate portion 82 and the upper bent portion 81 and is connected to the bottom wall 74 so that the casing 72 extends over the entire length of the casing 72 in the longitudinal direction. And the intermediate portion 8
A second switch unit 90 is defined between the second switch unit 2 and the bottom wall 74.

The first switch section 86 is connected to the end wall 7.
6 and a pair of conductive members 9 disposed on the inner wall 84.
2,92. The second switch section 90 has a pair of conductive members 94, 94 disposed on the bottom wall 74 and the intermediate section 82. In addition, each of the conductive members 9
Reference numerals 2, 92, 94 and 94 are made of conductive silicon rubber, have a substantially flat plate shape, and are disposed over the entire length of the casing 72 in the longitudinal direction.

The upper bent portion 81 of the side wall 80
From the portion where the inner wall 84 is connected to the end wall 7.
The thickness of the side wall 78 on the sixth side is formed to be thinner than the thickness of the side wall 78 on the bottom wall 74 side and the thickness of the internal wall 88 from the portion where the lower bent portion 83 and the internal wall 84 are connected. Have been.

That is, the amount of deformation of the casing 72 when the first switch portion 86 is energized with respect to an external force acting on the distal end wall 76 in the direction of the arrow in the drawing is
The amount of deformation of the casing 72 when the second switch 90 is turned on is set smaller than the amount of deformation. That is, the first switch section 86 is energized by a small external stress, whereas the second switch section 90 is energized by a relatively large external stress.

The pressure-sensitive sensor 70 includes a pair of the conductive members 92 and 92 provided in the casing 72 and the first switch 86 and a pair of the conductive members 92 and 92 provided in the second switch 90. The conductive members 94, 94 and the inner walls 84, 88 dividing the inside of the casing 72 are integrally formed by extrusion.

FIG. 7 shows a fourth embodiment of the pressure-sensitive sensor 100.

The pressure-sensitive sensor 100 has a hollow elongated casing 102 made of insulating silicon rubber.

In the casing 102, the bottom wall 104 and the front end wall 106 facing each other have flat side walls 108.
And a side wall 110 bent in a step-like manner, and formed in a substantially L-shaped cross section.

The side wall 110 has an intermediate portion 112 substantially parallel to the bottom wall 104 and the front end wall 106, an upper bent portion 111 bent upward from the intermediate portion 112 and connected to the front end wall 106. A lower bent portion 113 bent downward from the intermediate portion 112 and connected to the bottom wall 104.
And, it consists of.

The interior of the casing 102 is disposed on the inner wall surface of the intermediate portion 112 and is divided over the entire length in the longitudinal direction of the casing 102 by a conductive member 114 serving as a cathode and having one end connected to the side wall 108. A first switch section 116 is defined on the end wall 106 side.
Further, the casing 102 extends upward from the approximate center of the bottom wall 104 in FIG. 7 and is connected to the conductive member 114 so that the casing 102 is divided over the entire length of the casing 102 in the longitudinal direction. A second switch unit 120 is defined between the intermediate unit 112 and the bottom wall 104.

The first switch section 116 includes a pair of conductive members 1 including the conductive member 114 serving as a cathode and the conductive member 122 serving as an anode disposed on the tip wall 106.
14, 122. The second switch unit 120
Has a pair of conductive members 114 and 124 including the conductive member 114 serving as a cathode and the conductive member 124 serving as an anode disposed on the bottom wall 104.

Each of the conductive members 114, 122, 1
Reference numeral 24 is made of conductive silicone rubber, has a substantially flat plate shape, and is disposed over the entire length of the casing 102 in the longitudinal direction.

The upper bent portion 11 of the side wall 110
1 and the thickness of the side wall 108 closer to the distal end wall 106 than the portion where the conductive member 114 is connected is smaller than the lower bent portion 1.
13 and a side wall 108 closer to the bottom wall 104 than the portion where the conductive member 114 is connected, and a thinner wall than the inner wall 118.

That is, the first switch portion 11 is not affected by an external force acting on the distal end wall 106 in the direction of the arrow in FIG.
The amount of deformation of the casing 102 when the switch 6 is energized is set smaller than the amount of deformation of the casing 102 when the second switch 120 is energized. That is, while the first switch unit 116 is in an energized state with a small external stress, the second switch unit 12
0 is in an energized state by a relatively large external stress.

The pressure-sensitive switch 100 includes the casing 102, the conductive member 114 serving as a cathode,
The conductive member 122 disposed on the tip wall 106,
The conductive member 124 disposed on the bottom wall 104 and the inner wall 118 dividing the inside of the casing 102
And are integrally formed by extrusion molding.

[0056]

According to the first aspect of the present invention, the pressure sensor detects a small amount of deformation of the casing caused by an external force with the first switch, and detects a large amount of deformation of the casing with the second switch. can do.

By appropriately setting the shape of the casing, the amount of deformation of the casing when the first switch section is energized, and the amount of deformation of the casing when the second switch section is energized, Can be set as appropriate.

According to the second aspect of the present invention, since the one conductive member of the first switch is shared as the one conductive member of the second switch, the structure of the pressure sensor can be simplified. And the size of the pressure-sensitive sensor can be reduced.

According to the third aspect of the invention, it is possible to control the pedestrian protection device and the occupant device having different operating conditions.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a front bumper provided with a pressure-sensitive sensor according to the present invention.

FIG. 2 is a sectional view of a pressure-sensitive sensor according to the present invention.

FIG. 3 is a cross-sectional view of the front bumper when a person collides.

FIG. 4 is a perspective view when a person collides with a front bumper.

FIG. 5 is a sectional view of a pressure-sensitive sensor according to a second embodiment of the present invention.

FIG. 6 is a sectional view of a pressure-sensitive sensor according to a third embodiment of the present invention.

FIG. 7 is a sectional view of a pressure-sensitive sensor according to a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 4 ... Pressure sensor 20 ... Casing 28 ... 1st switch part 30 ... 2nd switch part 32 ... Conductive member 34 ... Conductive member

Claims (3)

[Claims] 1. A pressure-sensitive sensor in which conductive members facing each other at a predetermined interval are disposed along a longitudinal direction of the casing inside an elongated casing made of an insulating elastic material. And a second switch having a pair of opposing conductive members are provided in the casing such that the directions of the external forces to be detected match each other. A pressure-sensitive sensor, wherein the amount of deformation of the casing when the first switch is energized is set smaller than the amount of deformation of the casing when the second switch is energized. 2. The pressure-sensitive sensor according to claim 1, wherein one conductive member of the first switch unit is shared as one conductive member of the second switch unit. 3. A vehicle built in a front bumper of an automobile,
The state in which the pair of conductive members of the first switch section are energized with each other is the operating condition of the pedestrian protection device, and the state in which the conductive members of the first switch section and the second switch section are energized is the occupant. The pressure-sensitive sensor according to claim 1, wherein the operating condition of the protection device is satisfied.