JPH0670601B2 - Wheel friction coefficient measuring device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wheel friction coefficient measuring device for measuring a friction coefficient in a friction phenomenon acting on a circular rotating object (wheel).

[0002]

2. Description of the Related Art Soviet Union Patent Publication SU582469 is known as one of the devices for measuring the coefficient of friction acting on a wheel. This known example discloses a device for measuring the friction coefficient of a wheel, particularly for an automobile wheel, and for the friction phenomenon, in particular, a friction phenomenon with a road surface. Although this known example has a simpler configuration than the other known examples, the range of displacement of the rotary shaft of the wheel in the direction perpendicular to the rotary shaft is large and unsuitable for a practical vehicle, and the road surface friction coefficient is measured. Therefore, it can be applied only to a special vehicle for a measurement test for the purpose itself, and cannot be diverted to other fields in which the displacement width of the rotating shaft of the wheel cannot be increased.

[0003]

SUMMARY OF THE INVENTION The present invention eliminates the above-mentioned problems of the prior art, has a simple structure, and has no or small displacement of the rotary shaft in a direction perpendicular to the rotary shaft, An object of the present invention is to provide a wheel friction coefficient measuring device that can be applied to measurement of a road surface friction coefficient for the purpose of anti-lock braking of a vehicle.

[0004]

SUMMARY OF THE INVENTION The present invention as set forth in claim 1, which is proposed to solve the above problems, is a friction coefficient measuring device for a wheel, wherein a rotating shaft of the wheel is rotatably supported. A plurality of strain measuring means for measuring the radial compressive strain of the bearing are installed on the bearing along the circumference of the bearing, and the outputs of the plurality of strain measuring means are sent to a processing means for arithmetic processing. Means extracts the circumferential position of the bearing where the compression strain is maximum from the outputs of the plurality of strain measuring means, and the vertical direction acting on the wheel and the radial direction at the position along the circumference where the compression strain is maximum. It is characterized in that the friction coefficient of the friction phenomenon acting on the wheel is obtained by calculating the tangent of the angle with the direction of the drag force by the processing means. According to a second aspect of the present invention, there is provided a wheel friction coefficient measuring device, wherein an eccentric ring is rotatably supported on the rotary shaft of the wheel and the bearing of the rotary shaft, and the eccentric ring is rotatably supported on the bearing. It is rotatably supported,
Arranged so that the center line of the rotating shaft is located outside the center line of the bearing, the deflection measuring means for measuring the rotational displacement of the eccentric ring is provided, and the rotational displacement of the eccentric ring is measured by the deflection measuring means. Then, the friction coefficient in the friction phenomenon acting on the wheel from the rotational displacement is calculated by the processing means for calculating the friction coefficient.

[0005]

According to the first aspect of the present invention, since a plurality of strain measuring means for measuring the radial compressive strain of the bearing are installed on the bearing of the wheel along the circumference of the bearing, the radial measuring force acting on the bearing can be improved. It is possible to measure values at a plurality of locations along the circumference of the compressive strain, and from the output of the plurality of strain measuring means, the circumferential position of the bearing where the compressive strain is maximum is extracted, and the friction coefficient The friction coefficient can be calculated from the position in the circumferential direction by the processing means for calculating. According to a second aspect of the present invention, an eccentric ring is rotatably supported between the rotary shaft of the wheel and a bearing of the rotary shaft, and the eccentric ring rotatably supports the rotary shaft. The eccentric ring rotates depending on the magnitude of the coefficient of friction in the friction phenomenon that acts on the wheel, because it is supported and the center line of the rotating shaft is located outside the center line of the bearing. Cause displacement. The rotational displacement is measured by the deflection measuring means, and the friction coefficient is calculated from the rotational displacement by the processing means for calculating the friction coefficient.

[0006]

The examples shown here are examples of the embodiments, and the scope of the claims is not limited to the examples shown here. FIG. 1 shows a block diagram of the overall configuration of an embodiment of a wheel friction coefficient measuring device of the present invention. Strain measuring means 1
By processing the output signal of the above in the processing means 2, the friction coefficient in the friction phenomenon acting on the wheel is measured.
FIG. 2 shows an example of the installation state of the strain measuring means 1. The rotating shaft 3 of the wheel is rotatably supported by the bearing 4. The strain measuring means 1 is, for example, a strain gauge, and a plurality of strain gauges are installed along the circumference of the bearing 4 so as to measure the compressive strain acting on the bearing 4 in the direction perpendicular to the axis by the rotating shaft 3. The output signal of each strain measuring means 1 is sent to the processing means 2, and the distribution of the compressive strain acting on the bearing 4 in the circumferential direction is calculated from the measured value of each strain measuring means by, for example, rational function interpolation. This makes it possible to extract a position along the circumference where the compressive strain acting on the bearing 4 is maximized. By calculating the tangent of the angle between the radial direction at the position along the circumference where the compressive strain is maximum and the direction of the vertical reaction force acting on the wheel, the friction coefficient of the friction phenomenon acting on the wheel can be obtained. . The processing means 2 can be realized by an electronic circuit including a microprocessor, a memory, and an input / output interface (the electronic circuit thus configured is referred to as a computer circuit). The above construction is simple and the rotary shaft 3 does not displace in the direction perpendicular to the shaft. FIG. 3 shows a block diagram of the entire configuration in another embodiment of the present invention. The measurement signal of the deflection measuring means 5 is sent to the processing means 6, and the processing means 6 calculates the friction coefficient in the friction phenomenon acting on the wheels. The deflection measuring means 5 measures the rotational displacement of the eccentric ring 7 shown in FIG.
The eccentric ring 7 is rotatably supported by a bearing 8, and a circular hole is provided in the eccentric ring 7 so that the central axis is displaced and located from the central axis of the eccentric ring 7. 9 is rotatably supported. The deflection measuring means 5 measures the angle between the direction 10 of the normal force and the direction 11 of the rotational displacement of the eccentric ring 7 in the friction phenomenon acting on the wheel. The direction 11 of rotational displacement is defined as the direction from the center of the bearing 8 to the center of the rotating shaft 9. When the coefficient of friction in the friction phenomenon acting on the wheel is zero, the angle representing the rotational displacement of the eccentric ring 7 is zero. The angle increases as the coefficient of friction increases. Generally, the tangent of the angle corresponds to the coefficient of friction. Therefore, the processing means 6 obtains the friction coefficient by calculating the tangent of the angle. The processing means 6 can be realized by a computer circuit like the processing means 2. The above configuration is simple and the rotary shaft 9
Is only slightly displaced in the direction perpendicular to the axis.

[0007]

As will be understood from the above description, the wheel friction coefficient measuring device of the present invention has a simple structure, and the rotation axis of the wheel is not displaced in the direction perpendicular to the axis or is only slightly displaced. The friction coefficient due to the friction phenomenon that acts on the wheels can be easily and accurately measured. Therefore, it can be applied to the road friction coefficient measuring device for the purpose of practical anti-lock brake device, traction control device, etc. Generally, it can be widely applied to the measurement of the friction coefficient of the wheel in the situation where the displacement of the rotating shaft is not preferable.

[Brief description of drawings]

FIG. 1 is a block diagram of an overall configuration showing an embodiment of a wheel friction coefficient measuring device of the present invention.

FIG. 2 is a schematic diagram showing a structure of a bearing for a rotary shaft of a wheel in the embodiment shown in FIG.

FIG. 3 is a block diagram of an overall configuration showing another embodiment of the wheel friction coefficient measuring device of the present invention.

FIG. 4 is a schematic diagram showing a structure of a bearing of a rotary shaft of a wheel in the embodiment shown in FIG.

[Explanation of symbols]

 1 Strain measuring means 2 Processing means 3 Rotating shaft 4 Bearing 5 Deflection measuring means 6 Processing means 7 Eccentric ring 8 Bearing 9 Rotating shaft 10 Direction of normal force 11 Direction of rotational displacement of eccentric ring 7

Claims (2)

[Claims] 1. A plurality of strain measuring means for measuring a radial compressive strain of a bearing is installed on a bearing that rotatably supports a rotating shaft of a wheel along the circumference of the bearing. The output of the means is sent to a processing means for performing arithmetic processing, and the processing means extracts the position in the circumferential direction of the bearing where the compressive strain is maximum from the outputs of the plurality of strain measuring means, and determines the maximum compressive strain. It is characterized in that the friction coefficient of the friction phenomenon acting on the wheel is obtained by calculating the tangent of the angle between the radial direction at the position along the circumference and the direction of the normal force acting on the wheel by the processing means. , Wheel friction coefficient measuring device. 2. An eccentric ring is rotatably supported on the rotating shaft between a rotating shaft of a wheel and a bearing of the rotating shaft, and is rotatably supported on the bearing, and a center line of the rotating shaft is the above-mentioned. A process for calculating a friction coefficient by arranging the deflection measuring means arranged so as to be located off the center line of the bearing and measuring the rotational displacement of the eccentric ring, and measuring the rotational displacement of the eccentric ring by the deflection measuring means. A friction coefficient measuring device for a wheel, wherein a friction coefficient in a friction phenomenon acting on the wheel is calculated from the rotational displacement by means.