JPH0843215A - Instrument for measuring stress of vehicle - Google Patents

Abstract

PURPOSE:To enable an instrument for measuring stress of vehicle to measure a stress generated in the axle of a vehicle or a structure near the axle with high accuracy by using a stress sensor having a differential capacitor function. CONSTITUTION:The stress sensor S having a differential capacitor function is composed of a male electrode plate A and female electrode plate B and the electrode plates A and B respectively have comb-shaped electrodes a1-a4 and b1-b5 protruded from substrates (a) and (b) and meshed with each other at same intervals. When this sensor S is fitted to the axle of a vehicle or a structure near the axle, the intervals between the comb-shaped electrodes a1-a4 and b1-b5 of the electrode plates A and B change in one direction only corresponding to the shearing stress generated in the axle of the vehicle or the structure near the axle and the capacitance of the sensor S changes when the vehicle is braked suddenly. Therefore, the instrument can measure the stress in only one direction corresponding to the capacitance variation of the instrument.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle stress measuring device for measuring stress such as shear strain generated on an axle or a structure near the axle of a transportation vehicle such as an automobile, an aircraft and a railroad vehicle.

[0002]

2. Description of the Related Art As a measuring method for measuring a stress such as a shear strain generated on an axle of a transportation vehicle such as a transportation vehicle such as an automobile, an aircraft, a railroad vehicle or the like, or a structure near the axle,
There are a photoelastic method, a stress paint film method, a caustics method, a holography method, a strain gauge method, and the like, and the strain gauge method is generally widely used. There are a wide variety of strain gauges that are easy to handle, but a transducer must be used for stress measurement, and the strain gauge method receives stress in all directions applied to the strain gauge, so analysis is necessary. It is necessary to attach individual strain gauges to the axle or a structure near the axle to take out the necessary stress.

[0003]

A conventional stress sensor consisting of a strain gauge senses stress applied to the strain gauge in all directions, and therefore, for example, even if it is desired to measure a road surface frictional force, other crosstalk is included. Only stress can be measured, or it is necessary to attach a plurality of stress sensors consisting of strain gauges and measure unnecessary stress by stress sensors to remove them. In view of such a point, the present invention uses a stress sensor having a differential capacitor function configured by a semiconductor process or the like to apply stress transmitted from the X direction, the Y direction, the Z direction, or the like of a vehicle axle or a structure near the axle. On the other hand, by utilizing the fact that only the stress in one direction is captured and the other stress is not reduced or concerned, the stress generated in the axle or the structure in the vicinity of the axle during the sudden braking of the vehicle can be accurately and simply measured. An object is to provide a stress measuring device for a vehicle.

[0004]

According to a first aspect of the present invention, a male electrode plate and a female electrode plate having a plurality of comb-blade electrodes provided at intervals on at least one side of a substrate are provided in respective combs. The blade electrodes are placed opposite to each other so that they are arranged between the other comb blade electrodes,
Change the male / female electrode plate for each stress direction in a direction that reduces the change with respect to the upper / lower and twist directions other than the forward / backward movement of either the male / female electrode plate, and only in the forward / backward direction. A stress sensor configured to form a differential capacitor function between the comb blade electrodes is attached to a vehicle axle or a structure in the vicinity of the axle, corresponding to shear strain generated in the axle or the structure in the vicinity of the axle, The stress sensor is configured so that the stress can be measured by sensing only in one direction orthogonal to the comb blade electrode. According to a second aspect of the present invention, a signal processing circuit such as an amplifier circuit connected to the male electrode plate and the female electrode plate is integrally formed on the substrate of the stress sensor. The present invention according to claim 3 provides the stress sensor according to claim 1 or 2,
It is attached to a stress measuring means consisting of a hole in a vehicle body or a structure near the axle, and the capacitor capacitance between the comb blade electrodes of the stress sensor is changed according to the shear strain generated in the axle or the structure near the axle. The amount of change is directly extracted as a stress signal. The present invention according to claim 4 is
An axle or a structure near the axle of the vehicle is provided with a stress measuring means for measuring a vertical load and a stress measuring means for measuring a road surface frictional force, and the stress sensor is attached to each stress measuring means, respectively. The stress sensor directly detects the vertical load corresponding to the shear strain generated on the axle or the structure near the axle, and the other stress sensor directly detects the road friction force corresponding to the shear strain generated on the axle or the structure near the axle. The detection signal is arithmetically processed to obtain the road surface friction coefficient.

[0005]

According to the present invention as set forth in claim 1, the stress sensor having the differential capacitor function is attached to the axle of the vehicle or the structure near the axle, so that when the vehicle is suddenly braked, the stress is applied to the axle or the vicinity of the axle. In accordance with the shear strain generated in the structure, the spacing between the comb blade electrodes of the male and female electrode plates of the stress sensor changes only in one direction that works in the stacking direction of the electrode plates, that is, the orthogonal direction, to change the capacitance. It is possible to measure the stress in only one direction corresponding to the amount of change. According to a second aspect of the present invention, by integrally forming a signal processing circuit such as an amplifier circuit on the substrate of the stress sensor according to the first aspect, it is possible to directly take out a capacitance change as a change amount of stress. it can. According to a third aspect of the present invention, a stress measuring means is formed by providing a hole in a vehicle axle or a structure near the axle, and the stress sensor according to the first or second aspect is attached to the stress measuring means. Thereby, the stress in only one direction can be measured more accurately. According to a fourth aspect of the present invention, the stress measuring means including a hole for measuring a vertical load and the stress measuring means including a hole for measuring a road surface friction force are separately provided on an axle of a vehicle or a structure near the axle. By mounting the stress sensors according to claims 1 and 2 separately in the holes of each stress measuring means and processing the output signals of both stress sensors, the road surface friction coefficient without crosstalk can be obtained. .

[0006]

The present invention is an example of the preferred embodiment, and the scope of the claims is not limited to the embodiment shown here. The present invention will be described below with reference to an example of a vehicle stress measuring device based on the illustrated embodiment. FIG. 1 is a basic configuration example of a stress sensor having a differential capacitor function. The stress sensor S is composed of a male electrode plate A and a female electrode plate B, and the size of the male electrode plate A in the thickness direction is smaller than that of the female electrode plate B. Further, the male electrode plate A and the female electrode plate B respectively include a plurality of comb blade electrodes a1 to a
a4 and b1 to b6, which are meshed with each other at intervals. The number of comb blade electrodes of the male electrode plate A is the same as that of the female electrode plate B.
It is desirable that the number of the comb-shaped electrodes is one less than the comb-shaped electrodes and the total number is an even number. The male electrode plate A is positioned at the center in the thickness direction of the thick female electrode plate B, and The comb blade electrode of the mold electrode plate A is arranged in the center between the comb blade electrodes of the female electrode plate B. The male electrode plate A and the female electrode plate B arranged in this way move when stress is transmitted in the stacking direction of the electrode plates, and the comb blade electrodes a1 to a4 of the male electrode plate A and the female electrode plate B are moved. It has a structure in which the distance between the comb blade electrodes b1 to b5 of the mold electrode plate B changes.

The arrow shown in FIG. 2 represents the shear stress applied to the stress sensor S, and at this time, both the comb blade electrode of the male electrode plate A and the comb blade electrode of the female electrode plate B move and both of them move. When the comb blade electrodes move in the directions of the arrows, the distance between the comb blade electrodes changes, and the capacitance between the two comb blade electrodes (conductors) changes. That is, when a stress that changes the distance between the comb blade electrodes of the male electrode plate A and the female electrode plate B acts, a voltage inversely proportional to the square of the stress (electrostatic attraction) can be measured. Of course, this electrostatic attraction is shear stress. The shear stress is the comb blade electrodes (a1 to a4, b1 to b1) of the stress sensor S.
The differential capacitor C formed in 5) is not applied from one direction, but is applied from other directions, that is, the stress applied from the direction perpendicular to the differential capacitor C and the pressure applied in the twisting direction. is there. In the stress sensor S shown in FIG. 1, when the male type electrode plate B moves upward or downward with respect to the female type electrode plate B with respect to the stress acting vertically, both of the comb blade electrodes (a1 to a4, b1) are moved. The distance between b5) to b5) does not change, which is the same as the state in which the electrostatic attraction does not work, and there is no voltage output. The same applies when the female electrode plate B moves with respect to the male electrode plate A. When the vertical stress acts on the entire stress sensor S, the comb-shaped electrodes of both the male electrode plate A and the female electrode plate B move in the same direction, which changes like a mountain shape or a valley shape. Even in this case, no voltage is output because the distance between the comb blade electrodes does not change. Further, with respect to the stress acting in the twisting direction, the male electrode plate A moves up and down with respect to the female electrode plate B, and also moves so as to change the distance between the comb blade electrodes. It seems that electrostatic attraction works and a voltage output is obtained. As described above, the stress sensor S
Always detects only the stress acting in the stacking direction of the male electrode plate A and the female electrode plate B, that is, in the orthogonal direction.

As shown in FIG. 3, the cross-sectional shape of the comb blade electrodes (a1 to a4) of the male electrode plate A is cylindrical rather than prismatic.
The cross-sectional shape of the comb blade electrodes (b1 to b5) of the female electrode plate B is formed into two types, a convex type and a concave type having a gentle radius of curvature, and the comb blade electrodes of the female electrode plate are the convex type and the concave type. Alternate combinations,
With the configuration in which the comb-shaped electrode of the male electrode plate is arranged between the convex-shaped comb-shaped electrode and the concave-shaped comb-shaped electrode, the male-shaped electrode plate A is directed upward with respect to the female-shaped electrode plate B. When the distance between the comb blade electrodes changes in the downward direction and the distance between the comb blade electrodes changes, the distance between the comb blade electrodes changes according to the relationship on the left side of FIG. The change is small or unchanged. Therefore, by canceling or not outputting the output on the side where the distance between the comb blade electrodes changes, it is possible to create a stress sensor that can easily cope with such movement. The differential capacitor having such comb-teeth electrodes is bonded to a frame made of the same material as the group IV element or steel to form the stress sensor S, or the frame is the same semiconductor as the differential capacitor. It is possible to make them simultaneously in the process.

In FIG. 4, a comb blade electrode (a) is formed on a substrate (frame) f.
1 to a4) and (b1 to b5) are connected or laminated to each other, and the temperature compensation is performed on the terminal block t for connecting the wiring by aluminum vapor deposition or the like connected to the comb blade electrode on a part of the substrate f. It is a stress sensor S in which a signal processing circuit e such as a circuit and an amplifier circuit is integrally formed. In addition, r shows an insulating part. FIG. 5 shows a stress sensor S manufactured by forming a substrate (frame) f separately from the comb blade electrodes and bonding them using a bonding technique. In this case, the alignment of the male and female comb blade electrodes is performed. It is necessary to join them while looking carefully. FIG. 6 shows a stress sensor S manufactured by a semiconductor process.
This does not join the substrate (frame) f afterwards, but makes the substrate (frame) f at the same time when the comb blade electrodes (a1 to a4) and (b1 to b5) are made. This stress sensor S differs from the above-mentioned one in that a bottom plate is attached to the substrate f. When the stress transmission capacity is significantly reduced, the bottom plate may be removed by a treatment such as etching. It should be noted that the semiconductor process has an advantage that a small stress sensor with high accuracy can be manufactured.

FIG. 7 shows a stress measuring device for a vehicle in which the stress sensor S is attached to a vehicle axle or a structure K in the vicinity of the axle. The stress sensor S is mounted in a hole which is a stress measuring means g. However, the hole is provided in the axle or the structure K near the axle. The stress measuring means g analyzes the stress distribution, and as shown in FIG. 8, the peripheral wall of the hole through which the shear stress generated when the sudden braking force is applied and the peripheral edge of the stress sensor are brought into contact with each other to be mounted. The position of the stress measuring means g opened on the strut is preferably provided at an optimum position in the stress distribution analysis by FEM analysis or the like. Please note that there are places where stress is not transmitted, and in this position,
The stress sensor cannot be aware of shear strain. However, even if a stress sensor is installed in a place where other stresses are transmitted, those stresses are not detected, so there is no need to consider it.

The stress measuring means g is made in the same direction as the traveling direction of the vehicle. This is for detecting the frictional force generated against the sudden braking force of the vehicle. Further, in order to obtain the road surface friction coefficient μ, it is necessary to measure the vertical load N and the road surface friction force F.
The stress measuring means for obtaining the vertical load N has a direction perpendicular to the position shown in the figure, which is different from the position in the figure. As the stress sensor S attached to the stress measuring means g, the same one as that used for measuring the road surface frictional force F can be used. The stress measuring means g for measuring the vertical load N, like the road surface friction force F, provides a hole in the axle or the structure K near the axle. Further, the position of the stress sensor S may be the same position as the stress sensor S that measures the road surface friction force F, or may be attached separately at a position where stress analysis is performed and stress concentration is measured, and the road surface friction force F and the vertical load N are respectively measured. The stress sensors are arranged so as to be orthogonal to each other. The hole which is the stress measuring means and the stress sensor are joined by using various adhesives, diffusion joining, electron beam welding, laser welding and the like. These are methods that can transmit the shear stress transmitted through the hole, which is the stress measuring means, to the stress sensor.
There are three types of joints between the hole and the stress sensor S, and there are three methods of contact-joining the inner surface of the hole and the frame, the inner surface of the hole and the frame and the electrode plate, and the inner surface of the hole and the electrode, and any method may be used. Alternatively, heat-resistant glass or the like may be anodically bonded to the inner surface of the hole in consideration of the strength of the stress sensor bonding portion. After joining the hole which is the stress measuring means and the stress sensor, there is a gap between the two. The gap may be filled with a material such as resin that does not transmit stress. After joining the hole composed of the stress measuring means and the stress sensor, it is desired to close the hole in consideration of waterproofing.

[0012]

[Effects] According to the present invention, it is possible to measure loads / stresses in only one direction purely with respect to loads / stresses applied to a stress sensor having a differential capacitor function in all directions. -Since stress can be measured by installing a stress sensor in that direction, stress sensors are installed at multiple points in order to eliminate crosstalk loads and stress, as with conventional stress sensors consisting of strain gauges. There is no need for a complicated device to obtain the load / stress in one direction from the vehicle, the stress measuring device is simple and small, and the load / stress in only one direction can be measured with one stress sensor. Can be easily attached to. Further, the stress measuring means for mounting the stress sensor does not have a particularly complicated structure and is formed by a hole. Therefore, no special technical force is required for mounting the stress sensor, and the stress measuring means can be easily mounted on the vehicle structure. Since the load / stress can be measured purely in only one direction, the road surface frictional force F and the vertical load N can be measured by two stress sensors to easily obtain the road surface friction coefficient μ.

[Brief description of drawings]

FIG. 1 is a perspective view showing a basic structure of a stress sensor.

FIG. 2 is an operation explanatory view of a comb blade electrode of the stress sensor shown in FIG.

FIG. 3 is a cross-sectional view showing a modified example of the comb blade electrode of the stress sensor.

FIG. 4 is a plan view showing another embodiment of the stress sensor.

FIG. 5 is a perspective view showing another embodiment of the stress sensor.

FIG. 6 is a perspective view showing still another embodiment of the stress sensor.

FIG. 7 is a perspective view showing an embodiment of a stress measuring device.

8 is an enlarged perspective view of a stress measuring means portion shown in FIG.

[Explanation of symbols]

 S Stress sensor A Male electrode plate B Female electrode plate a, b, f Substrate (frame) a1 to a4, b1 to b5 Comb blade electrode C Differential capacitor K Structure g Stress measuring means

Claims (4)

[Claims] 1. A male electrode plate and a female electrode plate, wherein a plurality of comb-blade electrodes are provided at intervals on at least one surface of a substrate, each comb-blade electrode being arranged between the other comb-blade electrodes. Align with each other and change the male / female electrode plate for each stress direction in a direction that reduces the change with respect to the upper / lower and twist directions other than the forward / backward movement. , A stress sensor that allows a differential capacitor function to be formed between the comb blade electrodes only in the front-rear direction is attached to a vehicle axle or a structure near the axle, and shear strain occurs in the axle or a structure near the axle. Corresponding to, the stress sensor senses the stress only in one direction orthogonal to the comb-teeth electrode to measure the stress. 2. The stress measuring device for a vehicle according to claim 1, wherein a signal processing circuit such as an amplifier circuit connected to the male electrode plate and the female electrode plate is integrally formed on the substrate of the stress sensor. . 3. The stress sensor according to any one of claims 1 and 2 is mounted on a stress measuring means comprising a hole provided in an axle of a vehicle or a structure near the axle, and shear strain is generated in the axle or the structure near the axle. A stress measuring device for a vehicle, wherein the capacitor capacitance between the comb blade electrodes of the stress sensor is changed according to the above, and the amount of change is directly taken out as a stress signal. 4. A structure near an axle or wheels of the vehicle,
A stress measuring means for measuring a vertical load and a stress measuring means for measuring a road frictional force are provided, and each stress measuring means is equipped with the above-mentioned stress sensor respectively, and one stress sensor is generated on an axle or a structure near the axle. Vertical load corresponding to shear strain,
The other stress sensor directly detects the road surface friction force corresponding to the shear strain generated on the axle or a structure near the axle, and calculates the detection signals of both to extract the road surface friction coefficient. Item 5. The vehicle stress measurement device according to items 1 to 3.