JPH0363012B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a road surface skid resistance measuring device.

[Prior art and its problems] When the surface of asphalt pavement becomes slippery,
When a car suddenly stops, overtakes someone, or drives around a curve, the car's tires may slip, causing a traffic accident.

Therefore, in order to find out how slippery the pavement is, the road surface slip resistance coefficient is measured.

The method of measuring the coefficient of road skid resistance is as follows: (i) Lower a pendulum with a rubber tip at a certain height, rub the rubber tip on the road surface, and measure the height at which it slides up. Portable tester method for measuring road surface skid resistance; (ii) Trailer method, in which the brakes are applied to the wheels of a trailer and the force required to tow the trailer at a constant speed is measured, and the drag coefficient is calculated from the frictional resistance; ( iii) A deceleration method in which a simple accelerometer is installed on a test vehicle running at a constant speed and the acceleration is measured when all wheels are locked by sudden braking; (iv) A test vehicle running at a constant speed. The braking distance method, which measures the distance from the point where the brakes are applied suddenly to the point where the vehicle comes to a complete stop, has been proposed.

Among these methods, the other 3 except the trailer method
All of these methods had various disadvantages, such as having to be carried out with road traffic blocked, making the measurements large-scale.

Regarding the trailer method, although it is possible to measure while driving, the production cost is high and
There was a problem that the measuring wheel had a large amount of wear and had a short lifespan.

The present invention was made in view of the above circumstances, and
The purpose of the present invention is to provide a long-life road surface skid resistance measuring device.

[Means for Solving the Problems] Therefore, in the present invention, a speed change means is disposed on one of two measuring wheels that are pulled by a traction means and rotate in the same direction on the road to be measured. , the respective axes of these two measuring wheels are connected via a torsion bar, and a difference is created between the rotational speeds of the two measuring wheels by a transmission means, and the torque of the torsion bar caused by the sliding resistance of the road surface is detected. The road surface skid resistance is measured using this method.

[Function] In other words, the two measuring wheels move on the road surface while being rotated by the traction force.
If there is no speed change means, both measuring wheels rotate in the same way,
No torque is generated in the torsion bar.

However, when one measuring wheel is accelerated or decelerated by the speed change means, the rotating force of the faster measuring wheel pulls the slower measuring wheel, causing it to slip on the road surface. Torque is generated in the torsion bar that connects the rotating shafts of both measurement wheels in proportion to the sliding resistance at this time. FIG. 4 is a diagram showing the relationship between torque and frictional resistance.

This torque T is expressed by the following formula: T=A・μ・W・R μ: Road friction coefficient W: Wheeled cart R: Measuring wheel radius A: Coefficient of force transmission loop Therefore, torque T can be measured. Accordingly, the road surface friction coefficient μ is calculated.

In this way, according to the present invention, it is possible to measure the slip resistance while running the vehicle on a road surface without applying sudden braking as in the conventional method. Furthermore, since there is no need to apply sudden braking, there is less wear on the measuring wheel, resulting in an extremely long life of the device.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an overall schematic diagram of a road surface skid resistance measuring device according to an embodiment of the present invention, and FIG. 2 is a diagram showing a measuring ring of the same device.

This road surface skid resistance measuring device has a measuring ring S
and a towing wheel part K that pulls the measurement wheel part. The measuring wheel section includes a frame 1 connected to the tow wheel section K, and first and second measuring wheels 2a, 2 whose axles are independently supported by the frame.
b, a torsion bar 3, and a torque detector 4 that measures the torque generated in the torsion bar 3, and the first measuring wheel 2a is connected to one end of the torsion bar 3 via a first chain transmission mechanism 5a. , the second measuring wheel 2b is connected to the other end of the torsion bar 3 via a second chain transmission mechanism 5b and a transmission gear 6, and the rotational speed of the second measuring wheel is controlled by the transmission gear 6. For example, by reducing the speed by 0.8 times, a difference is created between the rotational speeds of both measuring wheels, and the slip resistance generated in the second measuring wheel is detected by a torque detector as torque generated in the torsion bar. .

The output of the torque detector 4 is connected to a calculator 7 that calculates a slip resistance coefficient from the torque.
Furthermore, a recording section 8 for recording the output of the arithmetic unit 7 and a display section 9 for displaying the information are provided.

Here, W is the wheel load, and the tip of the frame 1 is towed by the tractive force F of the towing vehicle K. It is also assumed that the radii of the two measurement wheels are the same R and that the transmission gear has a gear ratio of 1:0.8.

Next, the operation of this slip resistance measuring device will be explained.

When the frame 1 is pulled by the traction force F of the towing vehicle K, the first measurement wheel 2a rotates,
The rotational force is transmitted through the first chain mechanism 5a,
It is decelerated by the transmission gear 6 via the torsion bar 3, and is transmitted to the second chain transmission mechanism 5b, which applies rotational force to the second measuring wheel 2b.

This rotational force is then transmitted to the road surface.

Here, since there is a difference in rotation between the first and second measurement wheels, a torque corresponding to the magnitude of the friction coefficient of the road surface is generated in the torsion bar.

This torque T is measured by a torque detector, and the friction coefficient μ, that is, the slip resistance coefficient is calculated by the calculation unit 7 from the above equation, and is displayed on the display section 9 and recorded in the recording section 8.

In this way, the skid resistance coefficient is measured while the measuring wheel is being driven, with little disturbance to road traffic.

Additionally, since the measuring wheel does not require sudden braking, wear can be significantly controlled, thereby greatly increasing the life of the device.

Furthermore, since it is only necessary to detect torque, the structure is simple and miniaturization is easy.

Furthermore, since it has a measurement function at the towed part,
There is no effect of differences in towing vehicles, and highly reliable measurement values can be obtained.

Note that the skid resistance measurement position is approximately 1 m outside the road lane mark or center line, and the friction coefficient of the road surface that both measurement wheels are in contact with must be the same, so the spacing between both measurement wheels is Narrower is better.

Further, in the embodiment, a towing type road surface slip resistance detection device in which the measurement wheels are towed by a towing vehicle has been described. A bus-type road surface skid resistance detection device equipped with a measuring ring 30 as shown is also effective.

[Effects of the Invention] As explained above, according to the road skid resistance device of the present invention, two measuring wheels that rotate by applying traction are connected by a torsion bar, and one of these measuring wheels is changed in speed. By doing so, a rotational difference is forcibly created, and the road surface skid resistance is measured by detecting the torque generated in the torsion bar due to the road surface skid resistance, which greatly reduces wear on the measuring wheels. In addition to being able to extend the lifespan, the structure is simple and highly reliable measurement values can be obtained.

[Brief explanation of drawings]

FIG. 1 is an overall view of a road surface skid resistance measuring device according to an embodiment of the present invention, FIG. 2 is a diagram showing a measuring ring of the same device, and FIG. 3 is a diagram showing another embodiment of the present invention.
FIG. 4 is a diagram showing the relationship between torque and friction coefficient. K... Traction part, S... Measuring ring part, 1... Frame, 2
a... First measuring wheel, 2b... Second measuring wheel, 3... Torsion bar, 4... Torque detector, 5a... First chain transmission mechanism, 5b... Second chain transmission mechanism, 6... Speed change gear, 7 ...Arithmetic unit, 8...Recording section, 9
...display part, 10...front wheel, 20...rear wheel, 30...measuring wheel part.

Claims (1)

[Claims] 1. Two vehicles of the same radius that are towed by a towing vehicle, are arranged in parallel in a direction perpendicular to the traction force of the towing vehicle, and rotate on a road surface to be measured by the traction force of the towing vehicle. a measuring wheel; a torsion bar connecting these two measuring wheels; and a torsion bar provided between the torsion bar and one measuring wheel of the two measuring wheels, and forcibly creating a rotation difference between the two measuring wheels. A road slip characterized by comprising: a speed change means; a torque detection means for detecting torsional torque generated in the torsion bar; and an arithmetic means for calculating a slip resistance coefficient based on the detected torque of the torque detection means. Resistance measuring device.