JPH04102034A - Method and apparatus for measuring sliding friction resistance of road surface - Google Patents

Abstract

PURPOSE:To execute rapidly countermeasures for a frozen road surface by measuring friction resistance between the wheel and the road surface from the tension of a chain in rotation which corresponds to the ratio in the number of teeth between chain sprockets fitted to front and rear wheels. CONSTITUTION:When an apparatus is connected to the rear part of a tractor vehicle and made to run in traction, a tension of making a front wheel 16 for testing rotate forcibly always acts on a chain 27 on an unfrozen road surface, since the number of teeth of a chain sprocket 20 of a rear wheel 16a for testing is larger by several numbers than that of the wheel 16. Therefore, an idler pulley 23 is displaced upward and a large positive strain output is obtained in a beam-type load converter 24. When the vehicle proceeds onto a frozen road surface subsequently, the wheel 16 rotates in the same way substantially as on a normal road surface, since it is provided with a nonskid device. Since the wheel 16a is not provided with the nonskid device, however, a forced rotational force between the wheel 16 and the wheel 16a turns weak, the pulley 23 is displaced to be lower than on the normal road surface, and only a small positive strain output is obtained in the converter 24. Accordingly, a recorder or a monitor is provided on the tractor vehicle and this output strain is recorded automatically.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for measuring the sliding friction resistance of a road surface from the tension of a chain stretched across sprockets with different numbers of teeth fixed to one front and rear wheels. This invention relates to a method and device for measuring sliding friction resistance.

[Prior Art] In general, when deciding when to spray antifreeze agents used for road safety maintenance in the winter, or when issuing warnings to passing vehicles, managers use a patrol car to visually inspect the road surface or measure the road surface temperature at fixed points. Slip resistance measurement is performed by applying 100% braking to a test shaft mounted on a relatively large vehicle and measuring the running resistance and braking force generated at that time to measure the frictional resistance of the road surface. equipment is used.

[Problems to be Solved by the Invention] However, due to the various road environments, it is not possible to accurately measure the sliding friction resistance of the road surface by visual inspection or road surface temperature measurement, and there is a problem that variations occur depending on the measurer. was there. In addition, in the case of measuring the sliding frictional resistance of the road surface using the above-mentioned sliding resistance measuring device,
For example, in the case of a frozen road surface in winter, the measured value will be a completely different value unrelated to the sliding friction resistance value of the road surface, and the road surface is often extremely slippery. This determination is an important issue in terms of ensuring the safety of moving vehicles and the response of site managers.

In order to solve the problems with such a method and device for measuring the sliding friction resistance of a road surface, the present invention is designed to dynamically measure the sliding friction value of a road surface directly on-site using a simple method or device to measure frozen road surfaces. It is an object of the present invention to provide a method and device for measuring the sliding friction resistance of a road surface, which allows quick identification and various countermeasures.

[Means for Solving the Problems] The present invention is characterized in that a pair of front and rear test wheels, each having a fixed chain sprocket having a different number of teeth and a chain stretched between both chain sprockets, are attached to an underframe. The sliding friction resistance of the road surface is measured by measuring the tension of the chain that occurs when this underframe is towed by a vehicle and driven on the road surface.

The present invention also provides an underframe that is removably connected to a vehicle;
A pair of front and rear test wheels pivotally mounted on this underframe, a chain sprocket with a different number of teeth fixed to both test wheels, and a chain stretched across both chain sprockets. and a load converter connected to this chain via an idler pulley.

In this combination, the front test wheel has greater frictional resistance than the rear test wheel, and the chain sprocket fixed to the rear test wheel has a higher frictional resistance than the chain sprocket fixed to the front test wheel. It is preferable that the sprocket has a large number of teeth.

[Operation] A device configured as described above is connected to the rear of the vehicle,
When towing, both the front and rear test wheels rotate along the unevenness of the road surface, but because the number of teeth on the sprocket of one test wheel is greater than the number of teeth on the sprocket of the other test wheel, there is a large frictional resistance on the road surface. In other words, on a road surface that is not frozen, there is always a large tension acting on the chain to forcibly rotate the test wheel with the smaller number of teeth on the sprocket. In this case, there is a tension force acting on the chain that forces the test wheel with the smaller number of sprocket teeth to rotate, but the value is small.By measuring these tension forces with a known device, it is possible to calculate the sliding friction on the road surface. Measure resistance.

[Embodiments] Hereinafter, embodiments of the method and apparatus for measuring the sliding friction resistance of a road surface according to the present invention will be described with reference to the drawings.

It is formed into a planar shape, and the bolt 1 at the front makes it approximately Y.
A pair of front and rear wheel axles 4.48 are attached to bolts 5 at the front and rear ends of the underframe 3, to which the rear open leg ends of the letter-shaped towing fittings 2 are pivotally attached.
．． It is attached by 5a.

The tip of the towing fitting 2 is provided with a bearing 7 and a pin 8 for pivoting the rear end of a connecting rod 6 for connecting to a towing vehicle (not shown) so that the connecting rod 6 can move in an arc in the vertical direction. A shaft hole 9 is formed at the tip of the connecting rod 6 to allow circular movement in the horizontal direction.

Supports 10 are installed at each of the four corners of the upper surface of the underframe 3,
A receiving plate I+ is fixed on the upper surface of each column IO so that the upper surface of each column In is on the same plane, and a pair of left and right weight support plates 12 parallel to the direction of movement are attached to this receiving plate. 11 via a damper 13.

On the weight support plate 12, a weight 14 with a weight suitable for the test wheels described later is placed so that it maintains left and right balance with respect to the traveling direction and applies a substantially equal load to both the front and rear test wheels. It is detachably attached to the top and bottom of the weight support plate 12 with screws 15.

At the center of the aforementioned l pair of front and rear wheel axles 4.48, there are a pair of front and rear test wheels 16 of the same diameter that are rotatable in the direction of travel, respectively.
．． 16a are each attached via a sleeve 17 for axial adjustment.

As the test wheel 16, the test wheel 15 is used as the test wheel 16.
16.16 Both front and rear test wheels 16.16 using wheels with higher frictional resistance than a, such as spiked tires, and using wheels such as regular tread tires as the test wheels.
Each frame of a has a chain sprocket 19.
．． 20 is fixedly installed, and the number of teeth of the chain sprocket 19 of the test wheel 16 is several fewer than the chain sprocket 20 of the test wheel 16a.

Between both axles 4.4a, a pedestal 2 is located slightly behind the underframe 3.
An idler pulley 23 is pivotally attached to the other end of the arm 22, which is fixedly attached at one end to the lower side of the pedestal 21. The idler pulley 23 is attached to the lower surface of the arm 22 so as to be located below the line connecting the lower surfaces of both chain sprockets 19 and 20 when the arm 22 is horizontal.

A beam-type load converter 24 is attached to the lower side of the underframe 3 behind the pedestal 2I, and this beam-type load converter 24
A plate spring 25 whose tip comes into contact with the lower surface of the arm 22 with appropriate pressure is screwed onto the lower surface of the arm 22 with a bolt 26.

The chain 27 is stretched around the circumferences of the pair of chain sprockets 19, 20 and the idler pulley 23, maintaining appropriate tension without slack.

The tension of this chain 27 can be adjusted by
．． This is done by adjusting the distance between 4a. For this reason, the portion of the underframe 3 that supports the rear wheel axle 4a has a slide portion 28 formed into two parts.

When the device configured as described above is connected to the rear of a towing vehicle and the vehicle is towed while traveling, both test wheels 16, 16a rotate along the unevenness of the road surface, but the chain sprocket of the rear test vehicle width 16a rotates. Since the fraction of 20 is several more than the fraction of the test wheel I6, the chain 27 always tries to forcibly rotate the test wheel 16 on a road surface with a large coefficient of road friction, that is, a road surface that is not frozen. Due to the tension, the idler pulley 23 is displaced upward, and a large positive strain output is obtained at the beam-shaped load transducer 24. When the vehicle enters a frozen road surface, the test wheels 16 are equipped with anti-slip surfaces, so they rotate almost in the same way as on a normal road surface. The forced rotational force between the test rear axle 16a and the test rear axle 16a becomes weaker, the idler pulley 23 is displaced downward compared to when on a normal road surface, and the beam-shaped load converter 24 can only obtain a small positive strain output.

Therefore, if the towing vehicle is equipped with a known recorder or monitor that automatically records this output distortion, the driver can easily grasp the road surface condition.

That is, in Fig. 4, W...Test wheel load R...Test wheel contact radius Y...Chain sprocket effective radius μ...Friction coefficient F'...Load cell detection load T... Assuming chain tension.

T2 μx W x R/r From F=TXsinθ, μ=Fxr/sinθXWXR Here, since r-constant and θ=constant If r/sinθ=a (constant) u=aXF/WXR.

Therefore, the test wheel load W, the test wheel ground contact radius R
By measuring , the road surface friction coefficient μ can be calculated from the load F detected by the load cell.

[Effects of the Invention] Since the present invention is based on the above method and configuration, it has the following effects.

The frictional resistance between the wheel and the road surface is not measured by applying 100% braking to the test wheel, but the frictional resistance between the wheel and the road surface is measured from the tension of the rotating chain, which corresponds to the tooth ratio of the chain sprocket attached to the front and rear wheels. It measures the frictional resistance of road surfaces, from normal and safe roads to frozen roads.
Accurate sliding friction resistance values can be dynamically determined on-site, allowing quick measures to be taken according to the road surface conditions, such as notifications to vehicle drivers, warnings of driving restrictions, timing and range of antifreeze spraying, etc. In addition to being able to immediately determine the effectiveness of anti-freezing agent spraying, safety measures can be taken that are tailored to local weather and weather conditions, and driving regulations can be implemented in response to sudden weather changes. This has the effect of significantly improving safety measures.

In addition, the device itself can be constructed very simply, and when in use, it is sufficient to simply connect it to a towing vehicle and drive it, so it is easy to handle and use.

Furthermore, as shown in the examples, the front test wheel has greater frictional resistance than the rear test wheel, and the rear test wheel is fixed to the rear test wheel more than the chain sprocket fixed to the front test wheel. If the chain sprocket is configured to have a large number of teeth, it also has the effect of increasing the accuracy of the -layer sliding friction resistance value.

[Brief Description of the Drawings] The drawings show an embodiment of the road surface sliding friction resistance measuring device according to the present invention, in which Fig. 1 is a plan view of the main part, Fig. 2 is a front view of the whole, and Fig. 3 is a plan view of the main part. 4 is a side view of the main part, and FIG. 4 is an explanatory diagram of the principle of measuring sliding frictional resistance. 3...Underframe +6.16a...Front and rear test wheels 19, 20...
・Chain sprocket 23...Idler pulley 24...Beam type load converter 27...Chain diagram Z4: Beam type load converter

Claims (3)

[Claims] (1) A pair of front and rear test wheels each having a fixed chain sprocket with a different number of teeth and a chain stretched between both chain sprockets is attached to an underframe, and this underframe is pulled by a vehicle. A method for measuring the sliding frictional resistance of a road surface, characterized in that the sliding frictional resistance of the road surface is measured by measuring the tension of a chain generated when running on the road surface. (2) An underframe that is removably connected to the vehicle, a pair of front and rear test wheels pivotally connected to the underframe, and a chain with a different number of teeth fixed to each of the test wheels. A road surface sliding friction resistance measuring device comprising a sprocket, a chain stretched across both chain sprockets, and a load converter connected to the chain via an idler pulley. (3) The front test wheel has greater frictional resistance than the rear test wheel, and the teeth of the chain sprocket fixed to the rear test wheel are larger than the chain sprocket fixed to the front test wheel. 2. The road surface sliding friction resistance measuring device according to claim 2, wherein the device comprises a large number of devices.