JP2013050416A - Road surface friction coefficient measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a road surface friction coefficient measurement device which has a small and inexpensive configuration and is capable of accurately controlling a slip ratio while varying it in a wide range and accurately measuring a state of a road surface friction coefficient which varies depending on the slip ratio.SOLUTION: The road surface friction coefficient measurement device 100 includes driving means for rotationally driving a test wheel 120 whose outer circumference surface comes into contact with the road surface; and control means 180 which measures the friction coefficient between the test wheel 120 and the road surface. The test wheel 120, the driving means, and the control means 180 are supported by a dolly 110 that has a travelling wheel 130 and travels by towing or driving. The control means 180 optionally sets the slip ratio between the outer circumference surface of the test wheel 120 and the road surface.

Description

  The present invention relates to a road surface friction coefficient measuring device for measuring a friction coefficient between a test wheel and a road surface by contacting a road surface while driving a test wheel and measuring a rotational load thereof.

Managing how slippery a road or runway is is an important safety issue for cars and aircraft. The slipperiness is evaluated by how much friction there is between the road surface and the tire, and the road surface friction coefficient is a scale.
In general, the road friction coefficient of roads and airport runways is measured by running a measuring vehicle equipped with a measuring device. At this time, the friction between the road surface and the tire is caused by the tire against the road surface. It depends greatly on how much you slip. This degree of slip is called slip ratio,
Slip ratio = (forward speed−circumferential speed of tire outer peripheral surface) / forward speed, and takes a value of 0 to 1.
When the slip ratio is 0, the tire is rolling without slipping on the road surface, the road surface friction coefficient is very small, and when the slip ratio is 1, the tire is in a locked state. The road friction coefficient becomes large.
Thus, although the road surface friction coefficient changes depending on the slip ratio, the slip ratio that provides the maximum road surface friction coefficient is not constant and depends on the state of the road surface.

  Conventionally, in order to measure the coefficient of friction of the road surface, a modification was made to install a measurement tire (test wheel) in the center of the rear of the vehicle, and the test wheel rotated at a constant slip ratio against the running wheel was pressed against the road surface. A method of measuring the friction coefficient from the rotational load (non-patent document), and as a simpler mechanism, a test wheel is attached to the rear wheel of the vehicle via a support arm, and the test wheel is also at a constant slip ratio with respect to the traveling wheel. A method of measuring the friction coefficient from the rotational load (Patent Document 1) is known.

Further, as a device having a variable slip ratio, a method of attaching a test wheel equipped with a brake device to a measuring vehicle or a second vehicle pulled by the vehicle is known (Patent Document 2).
Furthermore, as a device that can change the slip ratio and control the slip ratio, a method of driving a test wheel mounted on a measurement vehicle with a motor is known (Patent Document 3).

JP 2001-183250 A JP-A-4-83147 JP-A-4-157341

National Aerospace Research Institute Report No. 1443 “Development of a Snow and Ice Runway Friction Coefficient Measuring Device”

However, in the measuring device in which the known slip ratio is fixed in the mechanism in the above-mentioned non-patent document, patent document 1, etc., only the road surface friction coefficient at a constant slip ratio can always be measured. There was a problem that it was not possible to measure accurately.
In addition, the test wheel is driven by linking with the traveling wheel, and the slip ratio of the test wheel is set in relation to the traveling wheel. However, the traveling wheel itself always generates a predetermined slip, and the traveling wheel Since the slip is not necessarily a constant value depending on the traveling condition and road surface condition, there is a problem that it is impossible to obtain a highly accurate slip ratio of the test wheel in the first place.

On the other hand, in the measuring device that makes the slip ratio variable by a known brake device in Patent Document 2 or the like, the traveling wheel itself is a test wheel, and slips by braking without locking up to an arbitrary value. Therefore, it is impossible to set a range where the slip ratio is large, and since the road surface friction coefficient is calculated from the instantaneous value while changing the slip ratio, the measurement accuracy decreases due to instantaneous fluctuations and noise. There was a problem that it could not be measured.
In addition, since a predetermined slip always occurs on the traveling wheel itself, there is a problem that the slip ratio cannot be set near zero.

Furthermore, in a measuring device that drives a test wheel mounted on a measurement vehicle with a motor to change the slip ratio, which is known in Patent Document 3 and the like, a test wheel, a loading device for the test wheel, In order to incorporate a motor, a torque shaft, etc., the vehicle structure and electric circuit must be significantly modified.
Since these devices are difficult to mount in a small vehicle, it is necessary to use a large vehicle such as a bus as a dedicated measuring device, and there is a problem that the measuring device is very large and expensive. there were.

  Therefore, the present invention is a road surface friction that is small and inexpensive, can be controlled with high accuracy by making the slip ratio variable over a wide range, and can accurately and accurately measure the state of the road surface friction coefficient that varies depending on the slip ratio. The object is to provide a coefficient measuring device.

  According to the first aspect of the present invention, the test wheel whose outer peripheral surface is in contact with the road surface, the driving means for rotationally driving the test wheel, the rotational load of the test wheel is measured, and the friction coefficient between the test wheel and the road surface is determined. A road surface friction coefficient measuring device having a control means for measuring, wherein the test wheel, the drive means, and the control means are supported by a carriage that has running wheels and travels by traction or propulsion, and the control means is the drive means. The problem is solved by controlling the slip ratio so that the slip ratio between the outer peripheral surface of the test wheel and the road surface can be arbitrarily set.

  In the invention according to claim 2, in addition to the configuration of the road surface friction coefficient measuring device according to claim 1, the driving means obtains the rotational driving force of the test wheel by the rotation of the traveling wheel. It is a solution.

  In the invention according to claim 3, in addition to the configuration of the road surface friction coefficient measuring apparatus according to claim 1 or 2, the control means includes a speed sensor that detects a ground speed of the carriage with respect to the road surface. The above-mentioned problem is solved.

  According to the fourth aspect of the present invention, in addition to the configuration of the road surface friction coefficient measuring device according to any one of the first to third aspects, the driving means is provided between the traveling wheel and the test wheel via a speed change mechanism. The problem is solved by providing a transmission mechanism for transmitting rotation and a braking mechanism for braking the test wheel.

  In addition to the configuration of the road surface friction coefficient measuring device according to claim 4, the invention according to claim 5 solves the above problem by the fact that the transmission mechanism includes a clutch and a continuously variable transmission mechanism. .

  In addition to the configuration of the road surface friction coefficient measuring device according to claim 5, the invention according to claim 6 solves the above problem by the stepless speed change mechanism being a hydraulic transmission mechanism having a variable rotation speed. is there.

  According to the seventh aspect of the present invention, in addition to the configuration of the road surface friction coefficient measuring device according to the fifth aspect, the continuously variable transmission mechanism includes an electric motor, a generator, and drive control means for the electric motor. Is a solution.

  According to an eighth aspect of the present invention, in addition to the configuration of the road surface friction coefficient measuring device according to any one of the first to seventh aspects, the carriage is provided with power supply means, and the measurement control means The problem is solved by operating with the power of the supply means.

  In the invention according to claim 9, in addition to the configuration of the road surface friction coefficient measuring device according to claim 7, the carriage is provided with power supply means, and the control means is operated by the power of the power supply means, The power supply means uses the power of the generator to solve the problem.

According to the road surface friction coefficient measuring apparatus according to the first aspect of the present invention, the test wheels, the drive means, and the control means are supported by a carriage that has traveling wheels and travels by traction or propulsion, thereby making the whole size small and simple and inexpensive. It can be set as a simple structure.
In addition, by independently controlling the test wheels by the drive means and the control means, and arbitrarily setting the slip ratio, the slip ratio can be varied over a wide range and can be controlled with high accuracy, and the state of the road surface friction coefficient that varies depending on the slip ratio Can be accurately measured with high accuracy.

According to the configuration of the second aspect of the present invention, the driving means obtains the rotational driving force of the test wheel by rotating the traveling wheel, thereby supplying power from a vehicle or the like for towing or propelling, or on the carriage. Since it is not necessary to separately install a power source for driving the test wheels, a simpler and cheaper configuration can be achieved.
According to the configuration of the third aspect of the present invention, since the ground speed of the carriage with respect to the road surface can be accurately measured, the slip ratio of the test wheel can be set more accurately without being affected by the slip of the traveling wheel. The slip ratio can be varied over a wide range and controlled with high accuracy, and the state of the road surface friction coefficient that varies depending on the slip ratio can be accurately measured with high accuracy.
According to the configuration of the fourth aspect of the present invention, when changing the speed ratio of the speed change mechanism and setting the slip ratio to a large state close to 1, the rotation speed of the test wheel can be quickly reduced by the braking mechanism. Therefore, the slip ratio can be varied more smoothly over a wide range and can be controlled with high accuracy.

According to the fifth aspect of the present invention, the slip ratio can be continuously controlled to an arbitrary value by the continuously variable transmission mechanism, and the slip ratio can be controlled by stopping the test wheel by the braking mechanism after stopping the driving by the clutch. Can be set to 1, so that the slip ratio can be varied more smoothly over a wide range and can be controlled with high accuracy.
According to the configurations described in claims 6 and 7, the continuously variable transmission mechanism can be reduced in size, the degree of freedom in arrangement can be improved, and the overall size can be further reduced.
According to the configurations of claims 8 and 9, since it is not necessary to supply power from a vehicle or the like for towing or propelling, a simpler and less expensive configuration can be achieved.

The side view of the road surface friction coefficient measuring device which is one Example of this invention. The top view of the road surface friction coefficient measuring device which is one Example of this invention. BRIEF DESCRIPTION OF THE DRAWINGS Schematic explanatory drawing of the drive means of the road surface friction coefficient measuring device which is one Example of this invention. The schematic explanatory drawing of the drive means of the road surface friction coefficient measuring apparatus which is the other Example of this invention. The schematic explanatory drawing of the drive means of the road surface friction coefficient measuring device which is further another Example of this invention.

  The road surface friction coefficient measuring device of the present invention includes a test wheel whose outer peripheral surface is in contact with the road surface, a driving means for rotationally driving the test wheel, a rotational load of the test wheel, and a friction coefficient between the test wheel and the road surface. A test wheel, a driving means, and a control means, which are supported by a carriage that has traveling wheels and travels by towing or propulsion, and the control means controls the driving means to control the outer peripheral surface and the road surface of the test wheels. The slip ratio can be arbitrarily set, and the whole can be made small and simple and inexpensive, and the test wheel can be controlled independently and the slip ratio can be set arbitrarily. Thus, the slip ratio can be varied over a wide range and can be controlled with high accuracy, and the state of the road surface friction coefficient that varies depending on the slip ratio can be accurately measured with high accuracy.

As shown schematically in FIGS. 1 and 2, a road surface friction coefficient measuring apparatus 100 according to an embodiment of the present invention includes a traveling wheel 130 and a cart 110 that is pulled by an automobile or the like via a connecting portion 111. The test wheel 120, the drive means, and the control means 180 are supported and configured.
The driving means includes a hydraulic pump 141 driven by the rotation of the traveling wheel 130 and a hydraulic motor 142 driven by pressure oil supplied from the hydraulic pump 141, and the test wheel 120 is driven to rotate by the hydraulic motor 142. Is done.
The hydraulic pump 141 is composed of, for example, a variable displacement pump, and the amount of pressure oil to be supplied is adjusted by controlling the transmission mechanism 160, and the rotational speed of the hydraulic motor 142 is controlled.
A brake mechanism 170 is provided on the output shaft of the hydraulic motor 142, and the driving force of the hydraulic motor 142 is released so that the test wheel 120 can be stopped.
The test wheel 120 is configured to be pressed against the road surface with a predetermined pressing force by the elevating mechanism 121 and to be able to release the ground contact with the road surface.

In addition, the traveling wheel 130 is supported by the carriage 110 via the suspension 131, and the test wheel 120 is pressed against the road surface with a predetermined force by the lifting mechanism 121. While running smoothly, the test wheel 120 is always grounded with a predetermined pressing force so that accurate measurement is possible.
In addition, auxiliary wheels 112 are provided on the carriage 110 so as to be able to appear and disappear with respect to the road surface. As a result, the road surface friction coefficient measuring apparatus 100 that is not connected to an automobile or the like can be easily moved independently, and can be quickly handled when not in use or at the start / end of use.

In FIG. 3, the schematic explanatory drawing relevant to the measurement operation | movement of the road surface friction coefficient measuring apparatus 100 which is one Example of this invention is shown.
When the carriage 110 is pulled by an automobile or the like, the traveling wheel 130 is rotated, and the hydraulic pump 141 is driven by the rotation.
The hydraulic pump 141 is provided with a speed change mechanism 160 so that the amount of pressure oil to be supplied can be adjusted.
The pressure oil supplied from the hydraulic pump 141 drives the hydraulic motor 142 via the hydraulic piping 150 that constitutes the transmission mechanism, and the test wheel 120 is rotationally driven by the hydraulic motor 142.
A brake mechanism 170 is provided on the rotating shaft of the test wheel 120.
Further, a ground speed sensor 181 for measuring the ground speed of the carriage 110 is provided at an arbitrary position, and a load sensor 182 is provided on the rotating shaft of the test wheel 120.

The control unit 180 can arbitrarily set the slip ratio between the outer peripheral surface of the test wheel 120 and the road surface, and can monitor or control the ground speed sensor 181, the load sensor 182, the speed change mechanism 160, the hydraulic motor 142, and the braking mechanism 170. It is configured.
As a result, the control means 180 makes an arbitrary ratio between the speed of the carriage 110 detected by the ground speed sensor 181 and the peripheral speed of the outer peripheral surface of the test wheel 120 calculated from the rotational speed of the hydraulic motor 142. In addition, by controlling the speed change mechanism 160, the slip ratio between the outer peripheral surface of the test wheel 120 and the road surface can be set accurately.
When the slip ratio is set to 1, that is, when the test wheel 120 is completely stopped, the braking mechanism 170 may be operated by the control means 180.
Since the diameter of the test wheel 120 and the pressing force against the road surface by the elevating mechanism 121 are known, the control means 180 determines the distance between the road surface and the test wheel 120 at an arbitrary slip ratio from the known value and the rotational load detected by the load sensor 182. The friction coefficient can be calculated.
The pressing force on the road surface may be detected in real time by providing a separate sensor without using a predetermined value set in the lifting mechanism 121 as a known value.
In addition, the specific configuration of each component member, sensor, and the like may be any as long as it can perform the above-described operation, and a known inexpensive component member can be used for each.

FIG. 4 shows another embodiment in which the driving means using the hydraulic pressure in the above embodiment is replaced with a mechanical configuration.
When the carriage 110 is pulled by an automobile or the like, the traveling wheel 130 rotates, and the rotation is transmitted to the continuously variable transmission 161 via the input clutch 143 and the gear unit 152.
The rotational output of the continuously variable transmission 161 is transmitted to the test wheel 120 via the output clutch 144 and the braking mechanism 170.
Further, a ground speed sensor 181 for measuring the ground speed of the carriage 110 is provided at an arbitrary position, and a load sensor 182 is provided on the rotating shaft of the test wheel 120.

The control means 180 can arbitrarily set the slip ratio between the outer peripheral surface of the test wheel 120 and the road surface, and the ground speed sensor 181, the load sensor 182, the input clutch 143, the continuously variable transmission 161, the output clutch 144, and the braking mechanism 170 can be monitored or controlled.
Thus, the speed of the carriage 110 detected by the ground speed sensor 181 by the control means 180 and the peripheral speed of the outer peripheral surface of the test wheel 120 calculated from the output rotational speed of the continuously variable transmission 161 are arbitrarily set. By controlling the continuously variable transmission 161 such that the slip ratio between the outer peripheral surface of the test wheel 120 and the road surface can be accurately set.
When the slip ratio is set to 1, that is, when the test wheel 120 is completely stopped, the input clutch 143 and the output clutch 144 may be released by the control means 180 and the braking mechanism 170 may be operated.

FIG. 5 shows still another embodiment in which the driving means using the hydraulic pressure or mechanical configuration in the above embodiment is replaced with an electrical configuration.
When the carriage 110 is pulled by an automobile or the like, the traveling wheel 130 is rotated, and the generator 145 is driven by the rotation.
The power generated by the generator 145 is supplied to the battery 154 and the electric motor 146 through the power line 153.
The electric motor 146 is configured to be able to arbitrarily adjust the rotation speed.
The rotation output of the electric motor 146 is transmitted to the test wheel 120 via the braking mechanism 170.
Further, a ground speed sensor 181 for measuring the ground speed of the carriage 110 is provided at an arbitrary position, and a load sensor 182 is provided on the rotating shaft of the test wheel 120.

The control means 180 can arbitrarily set the slip ratio between the outer peripheral surface of the test wheel 120 and the road surface, and is configured to be able to monitor or control the ground speed sensor 181, the load sensor 182, the electric motor 146, and the braking mechanism 170. Yes.
As a result, the speed of the carriage 110 detected by the ground speed sensor 181 by the control means 180 and the peripheral speed of the outer peripheral surface of the test wheel 120 calculated from the output rotational speed of the electric motor 146 become an arbitrary ratio. By controlling the continuously variable transmission 161 as described above, it is possible to accurately set the slip ratio between the outer peripheral surface of the test wheel 120 and the road surface.
When the slip ratio is set to 1, that is, when the test wheel 120 is completely stopped, the braking mechanism 170 may be operated.
The battery 154 may be omitted when the power supplied from the generator 145 is always sufficient to drive the electric motor 146, or may be shared with a battery that provides power for operating the control means 180. good.

In the above embodiment, description of output, display, recording, etc. of the calculation result of the road surface friction coefficient by the control means 180 is omitted, but the control means 180 is a general-purpose measuring device, input / output device, arithmetic device, programming device, etc. Can be combined, and may be performed by an appropriate means.
Further, the setting of the slip ratio and the changing operation of the slip ratio at the time of multipoint measurement may be performed in an optimum sequence using a general-purpose measuring device, input / output device, arithmetic device, programming device, or the like.

  The road surface friction coefficient measuring device of the present invention is suitable for applications that need to quickly measure and manage that the road surface friction coefficient has changed due to sudden changes in weather, etc., particularly on roads and airport runways in use.

DESCRIPTION OF SYMBOLS 100 ... Road surface friction coefficient measuring device 110 ... Carriage 111 ... Connecting part 112 ... Auxiliary wheel 120 ... Test wheel 121 ... Lifting mechanism 130 ... Running wheel 131 ... Suspension 141 ... Hydraulic pump 142 ... Hydraulic motor 143 ... Input clutch 144 ... Output clutch 145 ... Generator 146 ... Electric motor 150 ... Hydraulic pipe 152 ... Gear unit 153 ... Power line 154 Battery 160 Transmission mechanism 161 Continuously variable transmission 170 Braking mechanism 180 Control means 181 Ground speed sensor 182 Load sensor

Claims (9)

Road surface friction having a test wheel whose outer peripheral surface is in contact with the road surface, a drive means for rotationally driving the test wheel, and a control means for measuring a rotational load of the test wheel and measuring a friction coefficient between the test wheel and the road surface A coefficient measuring device,
The test wheel, the driving means and the control means are supported by a carriage that has traveling wheels and travels by towing or propulsion,
The road surface friction coefficient measuring device, wherein the control means is configured to be able to arbitrarily set a slip ratio between an outer peripheral surface of the test wheel and a road surface by controlling the driving means.   The road friction coefficient measuring device characterized in that the driving means obtains a rotational driving force of the test wheel by rotation of the traveling wheel.   The road surface friction coefficient measuring device according to claim 1, wherein the control means includes a speed sensor that detects a ground speed of the carriage with respect to the road surface.   The drive means includes a transmission mechanism for transmitting rotation between the traveling wheel and the test wheel via a speed change mechanism, and a braking mechanism for braking the test wheel. The road surface friction coefficient measuring device according to claim 3.   5. The road surface friction coefficient measuring device according to claim 4, wherein the transmission mechanism includes a clutch and a continuously variable transmission mechanism.   6. The road surface friction coefficient measuring apparatus according to claim 5, wherein the continuously variable transmission mechanism is a hydraulic transmission mechanism with variable rotation speed.   6. The road surface friction coefficient measuring device according to claim 5, wherein the continuously variable transmission mechanism comprises an electric motor, a generator, and drive control means for the electric motor. The carriage is provided with power supply means,
The road friction coefficient measuring device according to any one of claims 1 to 7, wherein the measurement control unit is operated by electric power of the power supply unit. The carriage is provided with power supply means,
The control means is operated by the power of the power supply means;
The road surface friction coefficient measuring device according to claim 7, wherein the power supply means uses the power of the generator.

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