JPH06288798A - Stress measuring device around suspension of vehicle - Google Patents

Abstract

PURPOSE:To provide a measuring device of the road surface friction force, the vertical load and the road surface friction coefficient which is a component of an anti-rock brake device or a traction control device. CONSTITUTION:Measuring means consisting of a strain gage F are arranged on an upper control arm A and an axle carrier of a suspension mechanism where the right and left wheels are capable of stroking, and the shearing strain generated in the upper control arm A and a rear axle carrier B when a vehicle is braked or driven.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a road surface friction force measuring device and a vertical surface friction force measuring device which can be an element constituting an anti-lock brake device or a traction control device for preventing wheel locking (fixation) during sudden braking of a vehicle. The present invention relates to a load measuring device and a road surface friction coefficient measuring device. [0002]

[0003] [0004] [0005] [0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a schematic configuration in which the present invention is applied to a rear wheel of a wheel composed of a suspension mechanism in which both left and right wheels can independently stroke, FIG. 2 is an enlarged perspective view of an essential part of FIG. 1, and FIG. b) and (c) show a device for measuring the road surface friction force. In this embodiment, the strain gauges 11 to 14 are used to measure the shear strain of the upper control arm A, which is a constituent member of the suspension mechanism. Detect frictional force. The strain gauge itself utilizes the fact that the electrical resistance of the resistance wire changes in proportion to the strain, and consists of a rectangular film with a built-in resistance wire, which detects tensile strain and compression strain in the longitudinal direction, Two sets of two strain gauges crossed in a cross, strain gauges 11, 12 and 13, 14 are placed on the rear desk 3 of the upper and lower sides of the upper control arm A.
It is affixed in the vicinity of the fixed portion to 5 so as to measure the tensile strain and the compressive strain in a direction forming an angle of approximately 45 ° with the axis 32 on an intersection line orthogonal to the traveling direction 31 of the rear wheel 30.
However, the strain gauges 11 and 14 and 12 and 13 are attached so as to be symmetrical with respect to the center line 33 of the upper control arm which is orthogonal to the traveling direction of the rear wheels. Instead of sticking the strain gauges 11 to 14, as shown in FIG. 3C, the strain gauges 11 and 12 are crossed on the surface of the substrate 36 made of plastic or other material, and the strain gauges 13 and 14 are formed on the back surface. The strain sensor F, which is attached by crossing with the cross, may be inserted and embedded in the through hole 37 provided in the upper control arm A. Instead of attaching the strain gauges 11 to 14 to the front and back surfaces of the upper control arm A, they may be attached symmetrically to the surface of the upper control arm A as shown by the chain line in FIG. [0007] When the wheels are braked, the upper control arm A is affected by the road surface frictional force applied to the rear wheels 30.
At the same time as bending deformation that the central axis bends on the horizontal plane,
A shear strain force having a magnitude equal to the road surface friction force is horizontally applied to a cross section perpendicular to the central axis of the upper control arm A. Shear strain is generated in the upper control arm A in proportion to the shear strain force. Strain gauges 11, 12,
By forming a bridge circuit D as shown in FIG.
It is possible to measure the road surface friction force by detecting the shear strain. In this case, by configuring the bridge circuit D, the influence of bending deformation is canceled out, and the voltage output of the amplifier 40 is proportional to only the road friction force applied to the rear wheel 30. [0008] FIG. 5 shows the bridge shown in FIG. In a specific configuration example of the circuit D, the lead wire 1 of the strain gauges 11 to 14 attached to the upper control arm A is connected to a 4-core shielded wire 42 composed of color-coded core wires via a terminal block 41, and the 4-core The cannon connector 43 provided at the free end of the shielded wire is detachably connected to the amplifier 40, which simplifies the construction and wiring of the bridge circuit.

[0009] FIGS. 6 and 7 show an embodiment of a road surface friction coefficient measuring device in which a vertical load measuring device is combined with a road surface frictional force measuring device, and the strain gauges 21 to 24 and 51 to 54 are used for rear wheels. The road surface frictional force and the vertical load are detected by measuring the shear strain of the rear axle carrier B, which is a component of the suspension mechanism of 30, and the road surface friction coefficient is measured by calculating both detected values. . Rear axle carrier B
A through hole 61 that is orthogonal to the load direction 70 is provided in the side wall portion 60, and a strain sensor F including the strain gauges 21 to 24 and a strain sensor N including the strain gauges 51 to 54 are inserted and embedded in the through hole 61. . In this case, each of the strain gauges 51 to 54 of the strain sensor N has an axis 71 orthogonal to the load direction 70 and approximately 4
The strain gauges 21 to 21 of the strain sensor F are arranged so that the tensile strain and the compressive strain in the direction forming an angle of 5 ° can be measured.
24 is arranged so that the tensile strain and the compressive strain in the direction forming an angle of approximately 45 ° with the axis orthogonal to the traveling direction of the rear wheels can be measured. [0010] When the wheels are braked, a road surface frictional force applied to the rear wheels applies a shear strain force equal in magnitude to the road surface frictional force to the rear axle carrier B in a cross section perpendicular to the central axis in the horizontal direction. Shear strain is generated in the rear axle carrier B in proportion to the force, and at the same time, the vertical load applied to the rear wheel causes bending deformation on the vertical surface (side surface) of the rear axle carrier B and also causes a vertical deformation with respect to the horizontal axis. A shear strain force of the same magnitude as a vertical load is applied to the cross section in the vertical direction, and shear strain occurs in the rear axle carrier B in proportion to this shear strain force. Strain gauge 21
.About.24 and 51 to 54 are assembled into two sets of bridge circuits D1 and D2 as shown in FIG. 8, and a voltage signal proportional to the road friction force obtained as the output of the amplifier 20 and a vertical signal obtained as the output of the amplifier 50 are combined. A voltage signal proportional to the load,
Each is input to the arithmetic circuit 80, the quotient of the road surface friction force and the vertical load is calculated by this arithmetic circuit, and a voltage signal corresponding to the road surface friction coefficient μ is output to measure the road surface friction coefficient. The through hole 61 is provided in the same direction as the vertical load direction 70 as shown by the chain line in FIGS. 6 and 7, and the strain sensor F
The strain sensor N may be inserted and embedded, and the through hole may be 2
Alternatively, the strain sensor F and the strain sensor N may be individually embedded by mistake. [0011] In the above embodiment, the strain sensor F and the strain sensor N are inserted and embedded in the through hole provided in the rear axle carrier B to measure the road surface friction coefficient, but the present invention is not limited to this. It is not a thing, but only the strain sensor N is inserted and embedded in the through hole of the rear axle carrier B,
Bridge circuit D of strain gauges 51 to 54 of the strain sensor N
2 and the bridge circuit D of the strain sensor F disposed on the upper control arm A shown in FIGS. 3 and 4 may be assembled as shown in FIG. 8 to measure the road surface friction coefficient, or as described above. Although the embodiment has described the components around the suspension mechanism of the rear wheels, the present invention is not limited to the rear wheels, and the present invention can be applied to the components around the suspension mechanism of the front wheels in the case of a vehicle. Of course. [0012]

According to the present invention, the shear strain generated during braking or driving can be accurately measured in the constituent members of the suspension mechanism without being affected by bending deformation, and particularly in the upper control arm and the rear axle carrier which are not rotating members. Since it is only necessary to install a strain gauge,
It is possible to easily measure the road surface friction force and the vertical load, and it is possible to obtain a highly accurate road surface friction coefficient from the measured voltage signals by arithmetic processing.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration in which the present invention is applied to a suspension mechanism of a vehicle in which both left and right wheels can independently stroke. FIG. 2 is an enlarged perspective view of a main part of FIG. FIG. 3 is a configuration diagram showing an embodiment of a road surface frictional force measuring device according to the present invention. [FIG. 4] A bridge circuit of the road frictional force measuring device shown in FIG. [FIG. 5] A specific configuration example of the bridge circuit shown in FIG. 4. [FIG. 6] A front view showing an embodiment of a road surface friction coefficient measuring device in which a vertical load measuring device is combined with a road surface frictional force measuring device according to the present invention. FIG. 7 is a side view of FIG. [FIG. 8] A bridge circuit of the road surface friction coefficient measuring device shown in FIG.

[Explanation of symbols]

 A Upper control arm B Rear axle carrier 11-14 Strain gauge 21-24 Strain gauge 51-54 Strain gauge 30 Rear wheel 31 Wheel traveling direction F Strain sensor N Strain sensor D, D1, D2 Bridge circuit 20, 40, 50, amplifier 70 Load direction 80 Arithmetic circuit

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[Procedure amendment]

[Submission date] March 15, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

[Title of Invention] Stress measurement around suspension of vehicle
apparatus

[Claims]

DETAILED DESCRIPTION OF THE INVENTION [0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a road friction force measuring device and a vertical load measuring device which can be elements constituting an anti-lock brake device or a traction control device for preventing wheel locking (fixation) during sudden braking of a vehicle. It also relates to a road surface friction coefficient measuring device. [0002]

2. Description of the Related Art In a conventional vehicle, for example, an anti-lock brake device for an automobile, a system is generally used in which braking is automatically controlled based on a vehicle speed and a wheel speed so that a slip ratio falls within a certain range. For example, Japanese Patent Publication Sho-59-30
585, JP-A-60-61354. ) The relationship between the road surface friction coefficient and the slip ratio can change depending on the road surface condition.
The braking force may not be maximum depending on road conditions, and in this case, the minimum braking distance cannot be obtained. Also,
Since the vehicle speed was an estimated value from the wheel speed, there was a problem in accuracy in controlling the slip ratio. In order to accurately grasp the vehicle speed, a ground speed sensor (for example,
A complicated device such as a vehicle body deceleration sensor (for example, Japanese Patent Laid-Open No. 63-64861) is required. In the conventional anti-lock brake device described in Japanese Patent Laid-Open No. 63-25169, the torque (tire torque) of the road surface frictional force acting on the wheel is calculated by calculation from the wheel angular acceleration and the brake fluid pressure, and the brake is applied. The beginning of the decrease in tire torque while the hydraulic pressure is increasing is used as one of the materials for determining the state immediately before the wheel is locked.
However, in this device, the tire torque is indirectly obtained by calculation from the wheel angular acceleration and the brake fluid pressure, and μ changes due to temperature changes such as the inertia ratio of the wheel and the use of the braked brake shoes (desk and desk pad). Since there is an uncertain constant such as the braking efficiency of the brake, there is a problem in accuracy of the calculated value. Also, depending on the tire pressure of the wheel and the weight of the vehicle body, the distance from the road surface of the wheel may change depending on the vehicle body deceleration, or the load on the tire during sudden acceleration such as braking may cause road surface friction and tire torque. There was also a problem that a constant ratio could not always be maintained. [0003]

SUMMARY OF THE INVENTION In view of the above problems of the conventional example, in the present invention, the frictional force between each wheel of the vehicle and the road surface is dynamically equivalent to the braking force exerted by the wheel on the vehicle body. Therefore, at any point of each structure from the ground contact point of the wheel to the road surface to the vehicle body, stress and strain proportional to the road surface friction force occur, and therefore, at an appropriate point in these structures. Measuring the strain of the structure, paying attention to the fact that the road friction force can be detected through this strain, and if the vehicle has wheels, the largest strain will occur in the tire. It is preferable to detect the road surface friction force based on this, but since the tire rotates, the measuring device is complicated and the cost is high. Therefore, although the strain amount is smaller than the tire, the configuration around the suspension of the vehicle that is not the rotating part Focusing on can be simplified and the measuring device for measuring the distortion of the wood, examples of a anti-lock braking system or traction control system to remove the drawbacks components capable of becoming road friction force and the like vertical load and road surface friction coefficient conventional An object is to provide a stress measuring device . [0004]

According to a first aspect of the present invention, stress measuring means, which is a strain gauge, is provided in a constituent member of a suspension mechanism that allows the left and right wheels to independently stroke, and when the wheel is braked or driven. The shearing stress of the suspension mechanism is measured by the stress measuring means . According to a second aspect of the present invention, the stress measuring means composed of a strain gauge is arranged on the upper control arm which is a constituent member of the suspension mechanism to reduce the road surface friction force.
The configuration is such that it is measured . According to a third aspect of the present invention, the stress measuring means composed of a strain cage is arranged on an axle carrier, which is a constituent member of a suspension mechanism, to provide a road surface.
It is configured to measure a frictional force or a vertical load .
The present invention is defined in claim 4, the components of the suspension mechanism, the road combined vertical load measuring means to the road surface friction force measuring means <br/> according to claim 2 and 3 are upper control arm or axle carrier Measure the friction coefficient
This is the configuration. The present invention according to claim 5 provides
The stress measuring means has a structure in which a pair of four strain gauges, each of which is a combination of two strain gauges, is formed in a bridge circuit. [0005]

According to the present invention as set forth in claims 1 to 4, since the stress measuring means consisting of a strain gauge is arranged in the constituent members of the suspension mechanism, the shearing that occurs in the constituent members of the suspension during wheel braking or driving. Strain is directly detected to obtain accurate road surface friction force, vertical load, road surface friction coefficient, etc.
Can measure stress . According to the fifth aspect of the present invention, since the strain gauge is combined with the cross to form the bridge circuit, the influence of the bending deformation is canceled out and the voltage signal proportional to only the road friction force or the vertical load can be taken out. [0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a schematic configuration in which the present invention is applied to a rear wheel of a wheel having a suspension configuration in which both left and right wheels can independently stroke, FIG. 2 is an enlarged perspective view of an essential part of FIG. 1, and FIG. b) and (c) show a means for measuring the road surface frictional force. In this embodiment, the strain cages 11 to 14 are used to measure the shear strain of the upper control arm A, which is a component of the suspension mechanism. Detect frictional force. The strain cage itself utilizes the fact that the electrical resistance of the resistance wire changes in proportion to the strain, and consists of a rectangular film with a built-in resistance wire, which detects tensile strain and compression strain in the longitudinal direction, Two sets of two strain gauges crossed in a cross, strain gauges 11, 12 and 13, 14 are placed on the rear desk 3 of the upper and lower sides of the upper control arm A.
It is attached in the vicinity of the fixed portion to 5 so as to measure the tensile strain and the compressive strain in a direction forming an angle of approximately 45 ° with the axis 32 on an intersection line orthogonal to the traveling direction 31 of the rear wheel 30.
However, the strain cages 11 and 14 and 12 and 13 are attached so as to be symmetrical with respect to the center line 33 of the upper control arm which is orthogonal to the traveling direction of the rear wheels. Instead of sticking the strain cages 11 to 14, as shown in FIG. 3C, the strain cages 11 and 12 are crossed on the surface of the substrate 36 made of plastic or other material, and the strain gauges 13 and 14 are placed on the back surface. The strain sensor F, which is attached by crossing with the cross, may be inserted and embedded in the through hole 37 provided in the upper control arm A. Instead of attaching the strain cages 11 to 14 to the front and back surfaces of the upper control arm A, they may be attached symmetrically to the surface of the upper control arm A as shown by the chain line in FIG. [0007] When the wheels are braked, the upper control arm A is affected by the road surface frictional force applied to the rear wheels 30.
At the same time as bending deformation that the central axis bends on the horizontal plane,
A shear strain force having a magnitude equal to the road surface friction force is horizontally applied to a cross section perpendicular to the central axis of the upper control arm A. Shear strain is generated in the upper control arm A in proportion to the shear strain force. Strain gauges 11, 12,
By forming a bridge circuit D as shown in FIG.
It is possible to measure the road surface friction force by detecting the shear strain. In this case, by configuring the bridge circuit D, the influence of bending deformation is canceled out, and the voltage output of the amplifier 40 is proportional to only the road friction force applied to the rear wheel 30. [0008] FIG. 5 is a specific configuration example of the bridge circuit D shown in FIG. 4, in which the lead wires 1 of the strain gauges 11 to 14 attached to the upper control arm A are colored from the core wires through the terminal block 41. It is configured to be connected to the four-core shielded wire 42 and the cannon connector 43 provided at the free end of the four-core shielded wire to be detachably connected to the amplifier 40, thereby simplifying the configuration and wiring of the bridge circuit.

[0009] Figs. 6 and 7 show an embodiment of a road surface friction coefficient measuring means in which a road surface friction force measuring means is combined with a vertical load measuring means , and rear cages are constructed by using strain cages 21-24 and 51-54. The road surface frictional force and the vertical load are detected by measuring the shear strain of the rear axle carrier B, which is a component of the suspension mechanism of 30, and the road surface friction coefficient is measured by calculating both detected values. A through hole 61 orthogonal to the load direction 70 is provided in the side wall portion 60 of the rear axle carrier B, and a strain sensor F including the strain gauges 21 to 24 and a strain sensor N including the strain gauges 51 to 54 are provided in the through hole 61. Insert and embed. In this case, each of the strain gauges 51 to 54 of the strain sensor N has an axis 71 orthogonal to the load direction 70 and approximately 4
The strain cages 21 to 21 of the strain sensor F are arranged so that the tensile strain and the compressive strain in the direction forming an angle of 5 ° can be measured.
24 is arranged so that the tensile strain and the compressive strain in the direction forming an angle of approximately 45 ° with the axis orthogonal to the traveling direction of the rear wheels can be measured. [0010] When the wheels are braked, a road surface frictional force applied to the rear wheels applies a shear strain force equal in magnitude to the road surface frictional force to the rear axle carrier B in a cross section perpendicular to the central axis in the horizontal direction. Shear strain is generated in the rear axle carrier B in proportion to the force, and at the same time, the vertical load applied to the rear wheel causes bending deformation on the vertical surface (side surface) of the rear axle carrier B and also causes a vertical deformation with respect to the horizontal axis. A shear strain force of the same magnitude as a vertical load is applied to the cross section in the vertical direction, and shear strain occurs in the rear axle carrier B in proportion to this shear strain force. Strain gauge 21
.About.24 and 51 to 54 are assembled into two sets of bridge circuits D1 and D2 as shown in FIG. 8, and a voltage signal proportional to the road friction force obtained as the output of the amplifier 20 and a vertical signal obtained as the output of the amplifier 50 are combined. A voltage signal proportional to the load,
Each is input to the arithmetic circuit 80, the quotient of the road surface friction force and the vertical load is calculated by this arithmetic circuit, and a voltage signal corresponding to the road surface friction coefficient μ is output to measure the road surface friction coefficient. The through hole 61 is provided in the same direction as the vertical load direction 70 as shown by the chain line in FIGS. 6 and 7, and the strain sensor F
The strain sensor N may be inserted and embedded, and the through hole may be 2
Alternatively, the strain sensor F and the strain sensor N may be individually embedded by mistake. [0011] In the above embodiment, the strain sensor F and the strain sensor N are inserted and embedded in the through hole provided in the rear axle carrier B to measure the road surface friction coefficient, but the present invention is not limited to this. It is not a thing, but only the strain sensor N is inserted and embedded in the through hole of the rear axle carrier B,
Bridge circuit D of strain gauges 51 to 54 of the strain sensor N
2 and the bridge circuit D of the strain sensor F disposed on the upper control arm A shown in FIGS. 3 and 4 may be assembled as shown in FIG. 8 to measure the road surface friction coefficient, or as described above. Although the embodiment has described the components around the suspension mechanism of the rear wheels, the present invention is not limited to the rear wheels, and the present invention can be applied to the components around the suspension mechanism of the front wheels in the case of a vehicle. Of course. Although the strain sensor uses the metal resistance wire strain gauge as the strain sensor, the strain sensor is not limited to this and a semiconductor strain gauge may be used. [0012]

According to the present invention, the shear strain generated during braking or driving can be accurately measured in the constituent members of the suspension mechanism without being affected by bending deformation, and particularly in the upper control arm and the rear axle carrier which are not rotating members. Since it is only necessary to install a strain gauge,
The road surface friction force and the normal load easily be measured, yet also processing accurate road friction coefficient of can be obtained an anti-lock brake system by these measured voltage signal
Can be a component of a traction control device
Stress measurement of road friction force, vertical load, road friction coefficient, etc.
The device can be easily provided.

BRIEF DESCRIPTION OF THE DRAWINGS [FIG. 1] A perspective view showing a schematic configuration in which the present invention is applied to a suspension mechanism of a vehicle in which both left and right wheels can independently stroke. FIG. 2 is an enlarged perspective view of a main part of FIG. FIG. 3 is a configuration diagram showing an embodiment of a road surface frictional force measuring device according to the present invention. [FIG. 4] A bridge circuit of the road frictional force measuring device shown in FIG. FIG. 5 is a diagram showing a specific configuration example of the bridge circuit shown in FIG. [FIG. 6] A front view showing an embodiment of a road surface friction coefficient measuring device in which a vertical load measuring device is combined with a road surface frictional force measuring device according to the present invention. FIG. 7 is a side view of FIG. [FIG. 8] A bridge circuit of the road surface friction coefficient measuring device shown in FIG.

[Explanation of Codes] A Upper Control Arm B Rear Axle Carrier 11-14 Strain Gauge 21-24 Strain Gauge 51-54 Strain Gauge 30 Rear Wheel 31 Wheel Travel Direction F Strain Sensor N Strain Sensor D, D1, D2 Bridge Circuit 20, 40, 50, amplifier 70 load direction 80 arithmetic circuit

Claims (5)

[Claims] 1. A measuring means composed of a strain gauge is provided in a constituent member of a suspension mechanism capable of independently striking both left and right wheels, and the shearing stress of the suspension mechanism during wheel braking or driving is measured by the measuring means. A device for measuring the road frictional force and vertical load around the wheel suspension and the road friction coefficient. 2. The road surface frictional force measuring device according to claim 1, wherein the constituent member of the suspension mechanism is an upper control arm. 3. The road frictional force or vertical load measuring device according to claim 1, wherein the constituent member of the suspension mechanism is an axle carrier. 4. A road surface friction coefficient measuring device in which a vertical load measuring device is combined with the road surface frictional force measuring device according to claim 2 or 3, wherein a constituent member of the suspension mechanism is an upper control arm or an axle carrier. 5. The road friction force and vertical force around a suspension of a vehicle according to claim 1, wherein the measuring means has a structure in which a pair of four pairs of two strain gauges combined in a cross is formed in a bridge circuit. Measuring device for load and road friction coefficient.