JPH045935B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an indoor testing method for tires for snowy and icy roads, and in particular, a test for the performance of tires on ice and a test for evaluating the degree of damage to paved roads caused by spiked tires, etc. It is related to the method of implementing the above.

[Conventional technology] Tire performance tests on ice have traditionally been carried out using actual vehicle tests in the field. Since it is not possible to conduct experiments with controlled ratios, there are problems such as the necessity of focusing on full braking tests and hill-climbing tests, and (3) the inability to ensure test repeatability. Also, when using a test vehicle for friction coefficient measurement, the above (1) and (3)
disadvantages are unavoidable.

On the other hand, it is possible to perform on-ice performance tests on drums or turntables, but because the length of the road surface used for driving is short, the same road surface is repeatedly driven in short cycles, and the temperature of the ice that forms the road surface is There is a problem that the ice may rise or the ice may partially melt due to pressure melting. Furthermore, when testing damage to a paved road surface, the test may become impossible due to an increase in road surface temperature.

[Problems to be Solved by the Invention] An object of the present invention is to use an indoor testing machine with a short road surface for running, such as a drum-type tire testing machine, to measure the rise in road surface temperature due to repeated running in short cycles. It is an object of the present invention to provide a method for carrying out a tire on-ice performance test and a road surface damage evaluation test that can ensure repeatability while suppressing the damage.

[Means and effects for solving the problems] In order to achieve the above object, the indoor test method for tires for snowy and icy roads of the present invention has an endless road surface on which the tire is repeatedly driven, and the steering angle and lateral displacement of the tire are measured. The controllable tire testing machine outputs a signal proportional to the distance traveled as the tire runs on the endless road surface, and synchronously controls the steering angle and lateral displacement of the tire in proportion to the distance traveled. The tire is characterized by running the tire in a slalom-like manner over the entire road width without side force.

To explain more specifically, in the ice performance test and road surface damage evaluation test of tires based on the present invention, drum type, turntable type, etc.
A tire testing machine is used that repeatedly uses the same road surface. This tire testing machine needs to be able to control the steering angle (slip angle) and lateral displacement of the tire from the outside, and also needs to be able to obtain a signal proportional to the distance traveled on the road surface.

Then, the steering angle and lateral displacement of the tires are synchronously controlled in proportion to the traveling distance, and the tires are caused to travel in a slalom manner without generating side force. This makes it possible to reduce the frequency of driving at the same location, use the road surface uniformly, and prevent temperature rise.

In addition, it is also possible to conduct an experiment in which a slip angle is substantially given by adding a constant steering angle to the steering angle in a state where the above-mentioned side force does not occur.

Such a test method can be extremely effectively used to understand the mechanism of frictional force generation between an icy surface and a roof, and the mechanism of damage to dry road surfaces caused by spiked tires.

[Example] FIG. 1 shows an example of an inside drum type tire testing machine suitable for use in tire testing according to the present invention. This tire testing machine is equipped with a drum 1 whose inner surface serves as a test track 2 and which is rotatably supported around a horizontal axis. It is possible to simulate road surface damage caused by the drum 1, and by providing a protruding collar 3 on the inner edge of the opening of the drum 1, it is possible to freeze water accumulated on the inner periphery and form an icy road surface on the inner periphery. It is. Therefore, the main parts of this tire testing machine are installed in a prefabricated freezing chamber whose atmosphere can be arbitrarily set within the range of -20°C to outside temperature.

The test tire 5 supported on the tire support stand 4 is
A method is adopted in which the drum is pressed horizontally against the inner surface of the drum by a pneumatic cylinder (not shown), and the ground load can be adjusted by adjusting the air pressure applied to the pneumatic cylinder. This test tire 5 is supported by a suspension system 7 via a six-component force meter 6, and is mounted so that the caster angle and camber angle can be adjusted by support arms. In particular, the suspension system 7 is equipped with a double wishbone type suspension system and an air spring in order to bring the compliance of the suspension system closer to that of an actual vehicle, which is considered to be a problem in spiked tire tests.

The tire support stand 4 is supported by a linear bearing guide (not shown) disposed in a direction parallel to the rotational axis of the drum 1, and the entire tire support stand 4 is moved onto the guide by a transverse feed motor 8. This enables traversal movement within the effective width of the test track 2. Further, the slip angle setting motor 9 provided on the tire support stand 4 is used to adjust the slip angle of the test tire 5 through the reduction gear 10 by its rotation. Furthermore, the above test tire 5
A tire dynamometer 1 is connected to the tire dynamometer 1 via a power transmission mechanism 11.
On the other hand, an encoder 13 and a drum dynamometer 14 are connected to the rotating shaft of the drum 1, which outputs a signal proportional to the distance traveled by the tire.

In the tire testing machine described above, the slip angle of the test tire 5 can be controlled by driving the slip angle setting motor 9 using an external signal or a programmable controller in the operation panel. In addition, the force generated in the tire is measured by a six-component force meter 6 using a piezoelectric element, and the force in the three wheel directions of the tire (ground load, traction force, side force),
The torque around these axes (self-aligning torque, rolling resistance moment, and overturning moment) is measured separately. The drum can be controlled in three ways: constant speed, constant torque, and running resistance control using a DC dynamometer 14 installed outdoors. In addition, the control of the power of the test tire shaft is as follows:
The dynamometer 12 must be installed in a low temperature room,
Since there is a high risk of brush problems caused by condensation with DC dynamometers, an AC servo motor is used to enable constant torque and constant speed control.

When using an indoor tire testing machine with the above configuration, the test road surface is endless, so when a spiked tire runs on the road surface in a straight line, the road surface corresponding to the track of the spikes is immediately damaged in a linear manner. This will prevent the spike from being effective. This inconvenience due to the tire traveling over the same point on the test road surface in short repeated cycles occurs even with tires without spikes. Figure 2 shows the temperature change on the test road surface when the slip angle was set to generate a side force of 300N with a wheel load of 2kN without the tire moving laterally. In this state, the tire surface temperature is 3℃~4℃
The temperature of the road surface increases accordingly, but this is thought to occur because the tires are repeatedly driven before the road surface releases the heat received from the tires. The reason why the measured surface temperature of the road surface does not rise monotonically is because the indoor temperature is controlled by turning on and off the refrigerator.

In order to eliminate such inconveniences, a control device is attached to the tire testing machine so that the test tire 5 is run in a slalom state without side force, and the tire runs uniformly within the effective width of the test road surface. .

In a tire testing machine equipped with this control device, the lateral feed and slip angle of the tire can be driven by external pulses at a rate of 0.01 mm and 0.01 degree, respectively, per pulse. On the other hand, due to the rotation of the drum, drum 1
Pulses proportional to the travel distance of the drum, which is 1024 pulses per rotation, are output. Therefore, if the increase/decrease in the slip angle and the increase/decrease in the lateral displacement are given as external pulses according to the pulses output every time the vehicle travels a fixed distance, the vehicle can travel on a fixed trajectory with fixed steering. I can do it. If you select the cycle to be an integer multiple of the drum circumference + α and slalom in a sinusoidal manner,
The displacement Y of the tire over the traveling distance X is as follows: Y=Asin2π/L+ΔLX (1). Here, A is the amplitude of the slalom, L is the circumferential length of the drum, and ΔL is a small value corresponding to α.
In order to prevent side force from occurring, each steering angle θ at each travel distance should be selected as follows: θ=2πA/L+ΔLcos2π/L+ΔLX (2).

Note that if X, Y, and θ are each given by pulse drive, only discrete values can be taken, so θ and Y can also be determined as follows. That is, (2)
Round each θn of steering at displacement Xn found by the formula to a feasible value, and calculate the displacement at Xn from this value and the travel distance.
Calculate Yn and increase/decrease θ and Y at Xn △θ and △
Prepare Yn as a table on the calculator. next,
For each travel distance pulse due to the rotation of the drum, △θn,
Slalom is performed by applying a pulse train corresponding to ΔYn (n=1, 2, . . . n) to each control device.

The results of a slalom test conducted with the same wheel load and slip angle as in the straight-ahead test confirmed that there was no rise in road surface temperature or partial damage to the road surface even after one hour of continuous driving.

[Effect of the invention] According to the method of the present invention detailed above, (1) The temperature rise of the ice is negligible.

(2) It is also possible to conduct tests on icy roads, which are similar to actual roads and have uniform potholes, without any partial damage to the road surface caused by spiked tires, etc.

(3) Even in experiments on paved roads, it is possible to prevent abnormal rises in road surface and tire temperatures, allowing experiments to be conducted under conditions close to actual driving.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing an outline of a tire testing machine suitable for use in carrying out the tire testing method of the present invention, and Fig. 2 shows a test road surface when a slip angle is given to the tire so as to generate a side force. It is a graph showing temperature changes on the surface. 2...Test track, 5...Test tire, 8...
Transverse feed motor, 9...Slip angle setting motor,
13... Encoder.

Claims (1)

[Claims] 1. In a tire testing machine that has an endless road surface on which it runs repeatedly and is capable of controlling the steering angle and lateral displacement of the tire, as the tire runs on the endless road surface, a signal proportional to the distance traveled is output, and the A tire for snowy and icy roads, which is characterized by synchronously controlling the steering angle and lateral displacement of the tire in proportion to the traveling distance, so that the tire runs in a slalom manner over the entire road surface without side force. Laboratory test method.