JPH1079211A - Pressure sensitive sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent excessive rise of the external force acting on a pressure sensitive sensor after the sensor has sensed a predetermined external force. SOLUTION: A second conductive member 43 is installed farther inside than a first conductive member 41, and farther inside a buffer member 44 capable of elastic deformation is installed, and a void 46 is formed inside the butter member 44. Even though a resisting body 45 is crushed by an external force, the external force is relieved by the buffer member 44, so that it is possible to prevent an external force acting on the pressure sensitive sensor from excessive rise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive sensor for detecting an external force from a direction intersecting a longitudinal direction, and relates to a power window when foreign matter is caught between a window glass and a window frame. It is suitable for use in an external force sensor for a window frame of a power window having a pinch prevention mechanism for preventing a pinch of foreign matter by reversing or stopping a motor for driving the motor.

[0002]

2. Description of the Related Art A pressure-sensitive sensor is disclosed in, for example,
As described in Japanese Patent Publication No. 122 (see FIG. 9), the periphery of the second conductive member 43 having a circular cross section is covered with a net-shaped first conductor 42 via a resistor whose resistance value changes according to elastic deformation. In addition, both conductors are disposed in a tube 41 made of an elastic member such as rubber.

[0003]

By the way, the present inventors conducted a test study using the pressure-sensitive sensor described in the above-mentioned publication as an external force sensor for a window frame of a power window with an anti-jamming mechanism. Such a problem occurred. That is, the power window with the anti-jamming mechanism detects the external force acting on the window frame by the pressure-sensitive sensor,
The motor is reversed or stopped when the detected external force exceeds a predetermined value (threshold).

However, there is a slight time difference (response delay) from when the pressure-sensitive sensor detects an external force exceeding the threshold value to when the motor is reversed or stopped. Foreign matter is caught. Also, changing (crushing) the cross-sectional shape of the pressure-sensitive sensor
If the force required for the above exceeds the elastic limit of the resistor (the resistor is completely crushed), the force required to change (crush) the cross-sectional shape of the first conductor is substantially equal to the force required. .

[0005] For this reason, when the motor continues to close the window glass after exceeding the elastic limit of the resistor, coupled with the response delay for reversing or stopping the motor, the force for pinching the foreign matter is greatly increased. There was a problem that it would be. On the other hand, a method of reducing the threshold value of the pressure-sensitive sensor is conceivable. However, if the threshold value is reduced, it is considered that the foreign object is caught even when the foreign object is not caught. Is likely to occur.

In order to reduce the response delay from when the pressure-sensitive sensor detects an external force of a predetermined value (threshold) to when the motor is reversed or stopped, a motor drive circuit and a control device are configured. Since the cost of the electronic component increases, the manufacturing cost of the power window with the anti-jamming mechanism also increases. In view of the above, an object of the present invention is to prevent an external force acting on a pressure-sensitive sensor from excessively increasing after the pressure-sensitive sensor detects a predetermined external force.

[0007]

The present invention uses the following technical means to achieve the above object. Claim 1
The invention described in Item 4 is characterized in that an elastically deformable buffer member (44) is provided inside the second conductive member (43) provided inside the first conductive member (41).

Accordingly, both conductive members (4
2, 43) even when approaching.
Since the external force is reduced by 4), it is possible to prevent the external force acting on the pressure-sensitive sensor from excessively increasing.
Further, according to the pressure-sensitive sensor according to the present invention, it is possible to prevent the external force acting on the pressure-sensitive sensor from excessively increasing by simple means such as disposing the buffer member (44) inside the second conductive member 43. When the pressure-sensitive sensor according to the present invention is used for a power window with an anti-jamming mechanism described later, the cost of the drive circuit of the drive motor (1) and the electronic components and the like constituting the control device (5) Ascent can be prevented.

Further, since it is not necessary to reduce the threshold value of the pressure-sensitive sensor, even when no foreign matter is caught, it is regarded that foreign matter has been caught, and the drive motor (1) is reversed or stopped. It is possible to prevent the occurrence of erroneous operation. The invention according to claim 2 is characterized in that a gap (46) for facilitating elastic deformation of the buffer member (44) is formed inside the buffer member (44).

As a result, the rigidity of the cushioning member (44) is reduced, and the cushioning member (44) is more easily deformed. Therefore, it is possible to further prevent the external force acting on the pressure-sensitive sensor from excessively increasing. The invention according to claim 3 is characterized in that at least one of the two conductive members (42, 43) is formed by spirally winding a band-shaped conductive material having a predetermined width.

When a bending moment acts on a beam-like object such as a pressure-sensitive sensor, a bending stress acts on each cross-sectional portion of the pressure-sensitive sensor, as is well known. The length in the longitudinal direction (axial direction) of (42, 43) changes, and both conductive members (42, 43)
43) The entire electric resistance value changes. For this reason,
When the pressure-sensitive sensor is disposed on the window frame, a bending moment acting on the pressure-sensitive sensor acts, so that the bending moment (bending stress), that is, the shape of the bent portion of the sensing sensor depends on the magnitude of the bending portion. The threshold value needs to be changed.

On the other hand, according to the present invention, the two conductive members (42, 4) are formed by spirally winding a belt-shaped conductive material.
3), when a bending moment acts on the pressure-sensitive switch, the two conductive members (42, 43)
Is deformed so that the pitch of the spiral portion changes like the coil spring. For this reason, when a bending moment acts on the pressure-sensitive sensor, shear stress (torsional stress) mainly occurs in both conductive members (42, 43).

Therefore, when the bending moment is mainly countered by the shear stress, the change in the axial length of the strip-shaped conductive material is smaller than when the bending moment is mainly countered. That is, even when a bending moment acts on the pressure-sensitive sensor, a change in the electric resistance of the conductive members (42, 43) can be reduced. As described above, according to the present invention, the conductive members (42, 4
Since the electric resistance of 3) is stabilized, it is not necessary to change the threshold value of the sensing sensor according to the shape of the window frame. As a result, the occurrence of the malfunction can be prevented, and the foreign substance entrapment can be reliably detected.

According to the fourth aspect of the present invention, the tube (4
1), both conductors (42, 43) and buffer member (44)
Are characterized by being arranged substantially concentrically. In addition, the code | symbol in the parenthesis of each said means shows the correspondence with the concrete means of embodiment mentioned later.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention; (First Embodiment) FIG. 1 shows a vehicle door having a power window with an anti-jamming mechanism, wherein 1 is a drive motor for driving a window glass 2 up and down, and 3 is a window frame. On the periphery of the window frame 3 on the indoor side, one pressure-sensitive sensor 4 for sensing an external force acting on the window frame 3 has a front side 3
a from the upper side 3b. And 5
Is a control device for controlling the drive motor 1 based on the signal 4a from the pressure sensor 4 and the power window switch 6 operated by the occupant.

As shown in FIG. 2, the pressure-sensitive sensor 4 has a cylindrical tube 4 made of an insulating material such as rubber.
1 and a first conductive member 42 formed in a cylindrical shape by knitting a conductive member such as a copper wire in contact with the inner wall of the tube 41 in a mesh shape.
A second conductive member 43 formed in a cylindrical shape by knitting a conductive member such as a copper wire disposed at a predetermined interval inside the first conductive member 42 into a mesh shape, and a second conductive member 43. And a cushioning member 44 made of an elastically deformable foam resin or the like disposed inside the member 43.

Further, the first and second conductive members 42, 43
A resistor 45 whose electric resistance value changes according to the internal stress of the conductive rubber or the like is provided between them, and the inside of the buffer member 44 facilitates the elastic deformation of the buffer member 44. A void 46 is formed. And tube 4
1, first and second conductive members 41 and 42, resistor 45,
The buffer member 44 is arranged substantially concentrically with each other.

Incidentally, the conductive rubber is, for example, a rubber in which carbon is mixed as a conductive member into the rubber and a large number of air bubbles are formed in the conductive rubber at the time of molding. The change in the electric resistance is performed by compressing the conductive rubber, thereby crushing the bubbles inside the conductive rubber and changing the number of bubbles forming an insulating portion in the conductive rubber. In the present embodiment, a predetermined voltage is applied between the conductive members 42 and 43 so that the pressure sensor 4 detects the pinching of a foreign substance. Then, when the electric resistance between the two conductive members 42 and 43 reaches a predetermined value (the two conductive members 41 and 43).
When the value of the current flowing between the rollers 42 reaches a predetermined value), the closing operation of the drive motor 1 is reversed or stopped, assuming that an external force of a predetermined value or more has acted on the window frame 3, that is, that foreign matter has been caught. Emit signal 5a.

Next, the features of this embodiment will be described. According to the present embodiment, the buffer member 44 is provided inside the second conductive member 43.
As described in the section of “Problems to be Solved by the Invention”, after the resistor 45 is completely crushed, the window is further reduced due to the response delay of the drive motor 1 and the control device 5. Even when the closing operation of the glass 2 proceeds, it is possible to prevent the external force acting on the pressure-sensitive sensor 4 from being excessively increased by the buffer member 44.

According to the present embodiment, the external force acting on the pressure-sensitive sensor 4 is prevented from excessively increasing by a simple means such as disposing the buffer member 44 inside the second conductive member 43. Therefore, it is possible to prevent the cost of the drive circuit (not shown) of the drive motor 1 and the electronic components constituting the control device 5 from increasing. Further, since there is no need to reduce the threshold value of the pressure-sensitive sensor, even when no foreign material is caught, it is considered that foreign material has been caught, and the drive motor 1 is reversed or stopped. Can be prevented.

As described above, according to the pressure-sensitive sensor 4 according to the present embodiment, the external force acting on the pressure-sensitive sensor 4 is excessively increased while preventing an increase in the manufacturing cost of the power window with the anti-jamming mechanism. Can be prevented. Further, since the gap 46 is formed in the cushioning member 44, the rigidity of the cushioning member 44 is reduced, and
Are more easily deformed. Therefore, it is possible to further prevent the external force acting on the pressure-sensitive sensor 4 from excessively increasing.

(Second Embodiment) In this embodiment, both conductive members 42 and 43 are formed by spirally winding a band-shaped conductive material having a predetermined width. As shown in FIG. 3, each conductive member formed by spirally winding the strip-shaped conductive material (hereinafter referred to as spiral conductive members 42a and 43a) is
They are wound alternately so that they do not overlap each other.

When a bending moment acts on a beam-shaped object such as the pressure-sensitive sensor 4, a bending stress acts on each section of the pressure-sensitive sensor 4 as is well known. And since this bending stress changes the length of the longitudinal direction (axial direction) of both conductive members 42 and 43, both conductive members 42 and 43
The electric resistance value of the whole 43 changes. Therefore,
When the pressure-sensitive sensor 4 is disposed at the bent portion A (see FIG. 1) of the window frame 3, a bending moment acts on the pressure-sensitive sensor 4, so that the magnitude of the bending moment (bending stress), that is, It is necessary to change the threshold value of the sensing sensor according to the shape of the bent portion A.

On the other hand, according to the present embodiment, the two conductive members 42 are formed by spirally winding a belt-shaped conductive material.
43, when a bending moment acts on the pressure-sensitive switch 4, the spiral conductive members 42a, 43
“a” is deformed so that the pitch of the spiral portion is changed, similarly to the coil spring. Therefore, when a bending moment acts, a shear stress (torsional stress) is mainly generated in both the spiral conductive members 42a and 43a.

Therefore, when the bending moment is mainly countered by the shear stress, the change in the axial length of the strip-shaped conductive material is smaller than when the bending moment is mainly countered. That is, even if a bending moment acts on the pressure-sensitive sensor 4, the conductive members 42 and 43 (the spiral conductive member 42
a, 43a), the change in electrical resistance can be reduced.

As described above, according to the present embodiment, the electrical resistance of the conductive members 42 and 43 is stable regardless of the shape of the window frame 3. There is no need to change the threshold. The occurrence of the erroneous operation can be prevented, and the foreign substance entrapment can be reliably detected.
In addition, as shown in FIG. 4, the present embodiment can be implemented even if the belt-shaped conductive material is densely wound so that the spiral conductive members 42a and 43a overlap each other.

As shown in FIG. 5, the first spiral conductive member 42a or the second spiral conductive member 43a and the band-shaped members 47 made of an insulating material may be densely arranged so as to be alternately located. Further, as shown in FIG. 6, the first spiral conductive member 42a or the second spiral conductive member 43a may be made of a plurality of strip-shaped conductive materials. In FIG. 6, the first spiral conductive member 42a is formed by winding two strip-shaped conductive materials, that is, a so-called double winding.

In the above-described embodiment, the tube 41, the conductive members 42 and 43, and the cushioning member 44 are arranged substantially concentrically in a substantially cylindrical shape.
The cross-sectional shape of 44 is semicircular (see FIG. 7) or elliptical (see FIG.
Reference). 7 and 8, reference numeral 48 denotes a copper drain wire (conductive wire) that suppresses a voltage drop when a current flows in the longitudinal direction of the conductive members 42 and 43. By embedding the drain wire 48 in each of the conductive members 42 and 43, the conductive members 42 and 43 have substantially the same potential irrespective of the position in the longitudinal direction of the pressure-sensitive sensor 4; However, the current value corresponding to the magnitude of the external force (the amount of deformation of the resistor 45) can be detected.

Further, each of the members 41 to 44 may be eccentric with respect to the center of the cross section (center of gravity) of the pressure-sensitive sensor 4. Further, in the above-described embodiment, as a specific means for the pressure-sensitive sensor 4 to detect an external force, a change in electric resistance between the conductive members 42 and 43 is used, but a change in capacitance between the conductive members 42 and 43 is used. Alternatively, the external force may be detected by using a change in other electric quantities such as the above.

The gap 4 formed in the buffer member 44
6 may be abolished.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a vehicle door having a power window with a pinch prevention mechanism.

FIG. 2 is a sectional view of a pressure-sensitive sensor.

FIG. 3 is a sectional view of a pressure-sensitive sensor according to a second embodiment.

FIG. 4 is an explanatory diagram showing a modified example of the pressure-sensitive sensor according to the second embodiment.

FIG. 5 is an explanatory diagram showing a modified example of the pressure-sensitive sensor according to the second embodiment.

FIG. 6 is an explanatory diagram showing a modified example of the pressure-sensitive sensor according to the second embodiment.

FIG. 7 is an explanatory diagram showing a modification of the pressure-sensitive sensor.

FIG. 8 is an explanatory diagram showing a modification of the pressure-sensitive sensor.

FIG. 9 is a perspective view of a pressure-sensitive sensor according to a conventional technique.

[Explanation of symbols]

41: tube, 42: first conductive member, 43: second conductive member, 44: buffer member, 45: resistor, 46: void.

Claims (4)

[Claims] 1. A pressure-sensitive sensor for sensing an external force from a direction intersecting with a longitudinal direction, comprising: a tube (41) made of an insulating material; and a tube (41) provided in the tube (41) and made of a conductive material. A first conductive member (42), and a second elastically deformable second conductive material disposed inside the first conductive member (42) with a predetermined distance from the first conductive member (42). A conductive member (43), wherein an external force acting on the tube (41) is detected by a change in an electrical physical quantity between the conductive members (42, 43), and further, the second conductive member (43) A pressure-sensitive sensor, further comprising an elastically deformable buffer member (44) disposed further inside. 2. A gap (46) inside the cushioning member (44) for facilitating elastic deformation of the cushioning member (44).
The pressure-sensitive sensor according to claim 1, wherein the pressure sensor is formed. 3. At least one of the two conductive members (42, 43) is formed by spirally winding a band-shaped conductive material having a predetermined width.
Or the pressure-sensitive sensor according to 2. 4. The tube according to claim 1, wherein the tube, the conductors, and the cushioning member are substantially concentrically arranged. The pressure-sensitive sensor according to any one of the above.