JPH0156375B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an improvement in a tire actual road wear test running method and device.

(Prior art) Conventionally, among the tire wear test driving methods, there have been many tests in the so-called actual vehicle driving method, in which tires are attached to an actual car and the wear state is evaluated by driving on actual roads such as ordinary roads and mountain roads. When testing tires, it takes a long time to run the test drive, and a large number of test drivers are required, which increases labor costs.In particular, in the case of accelerated wear tests, the wear caused by cornering takes up a large portion of the test drive. As the percentage increased, there were problems in determining the dangers of the driving test itself. Therefore, in order to solve this problem, the applicant installs at least two pairs of test tires on the test vehicle, and runs each test tire adjacent to the front and back on the left side or the right side at a different rotation speed. We found that it would be best to connect them using an appropriate connection mechanism, and we have already filed an application, but as a result of subsequent research,
Under certain conditions, such as when driving at low speeds, under high slip (that is, high severity) conditions, when the road surface is uneven, and when there are changes in the coefficient of friction of the road surface, a stable slip rate may be achieved due to the following reasons. As a result, the slip rate of two test tires connected to different rotation speeds suddenly changed, resulting in a significant difference in wear, making it difficult to measure and evaluate wear performance in a stable and highly accurate manner. It turned out that.

Reason: Under low speed conditions (especially when starting), the so-called adhesion of the rubber causes the tire's μ-S to decrease as shown in Figure 2.
At the same time that the characteristics (μ is the friction coefficient, S is the slip rate) change from ○A to ○B, the torsion spring of the tire case changes between the speed dependence of rubber friction and the balance system of friction torque of two test tires. Stakes slip occurs due to the presence of a spring with low stiffness, and the tire with the lower maximum frictional force exhibits large slip fluctuations.

In that case, even under test conditions μ ₁ with low severity, i.e., with a small slip difference, a high frictional force μ ₂ will occur, making it impossible to obtain the desired test conditions, and the fluctuation of the slip rate will increase, and the required traction force will be greater than the expected traction force. Sometimes the test vehicle becomes unable to start.

In particular, if you want to increase the severity and evaluate wear performance, you will increase the slip difference, but in that case, the amount of slip of the tire with lower maximum friction force will be greater than that of the other tire due to a slight change in conditions as described in . becomes extremely large.

μ-S characteristics as shown in Figure 1 (μ is the friction coefficient,
S is the slip rate) When the severity increases, the slip rate will be near the maximum frictional force P point, and a slight change in conditions will cause the tire to move in the direction of the greater slip rate, and the tire to move in the direction of the smaller slip rate. Large fluctuations in slip rate occur.

The unevenness of the road surface causes a change in the load between the two test tires, which changes the frictional force and causes the slip rate to fluctuate.

Even if there is no load change, the slip rate will change if the friction coefficient of the road surface changes locally.

In order to solve the above-mentioned problems, the applicant supported two linked test tires with left and right independent suspension, and lowered the spring constant of the suspension to reduce load fluctuations due to uneven road surfaces. Attempts have also been made to stabilize the tire load by pivoting the subframes of the two front and rear test tires in the center to enable pitching, but for the reasons stated above, the results were not satisfactory. I couldn't get it.

(Objective of the Invention) The present invention solves the above-mentioned problems, and when testing a large number of tires, the running time is short, and since only a small number of test drivers are required, labor costs are not increased. Furthermore, the actual road wear test running method not only allows a large number of test tires to be obtained in a single run, but also enables stable and highly accurate measurement and evaluation of wear performance under any running conditions or road surface conditions. The main purpose of the invention is to provide the following:

(Structure of the Invention) Therefore, in the actual road wear test driving method for tires of the present invention, at least two pairs of test tires are mounted on a test vehicle, and each test tire adjacent to the front and rear of the left side or the right side is The on-road wear test driving device of the present invention is characterized in that it is driven on an actual road at different rotational speeds while adding inertia. It is characterized by consisting of a pair of test tires, an inertia adding mechanism connected to a rotating system, and a connecting mechanism that connects each test tire adjacent to each other in the front and back on the left side or the right side so that they rotate at different rotation speeds. That is.

(Example) The present invention will be described in detail below with reference to the drawings.

In FIGS. 3 and 4, a test vehicle 1 has a drive wheel 2, a frame 3 supports sub-frames 5 and 6 via a spring 4, and the sub-frame 5 has two axles 7 and 8. Also, it is an independent suspension system in which two axles 9 and 10 are rotatably supported on the subframe 6, and the axles 7 and 8 are equipped with motorcycle test tires 1 of the same size, for example.
1 to 12 are mounted on the axles 9 and 10, and passenger car test tires 13 and 14 of the same size, for example, are mounted on the axles 9 and 10. 37 is tire oil.

Incidentally, test tires of the same size may be attached to all axles 7 to 10. 15 is the actual road surface.
The connecting mechanism 19 consists of a large-diameter sprocket 16 and a small-diameter sprocket 17 that are removably fixed to the axles 7 and 8, respectively, and a chain 18 stretched between these sprockets. It consists of a small diameter sprocket 20 and a large diameter sprocket 21 which are removably fixed to each of the axles 10, and a chain 22 stretched between these sprockets. Furthermore, the large diameter sprocket 21 on the left and the large diameter sprocket 16 on the right
The small diameter sprocket 20 on the left side and the small diameter sprocket 17 on the right side can have the same diameter or different diameters.

An inertia adding mechanism, for example, a flywheel (iron wheel) 24 to 27, is removably connected to and fixed to the rotation system of the test vehicle, specifically each of the axles 7 to 10, using a suitable locking jig. If the flywheel is independent suspension system as shown in Figure 5 instead of each axis,
One flywheel 36 may be connected to either of the pair of left axles 9, 10 and to either of the pair of right axles 7, 8, respectively. Incidentally, if the independent suspension system is not used as shown in FIG. 6, the flywheel 36 can be connected to either of the two front and rear axles connected to each other by a chain or the like. The size of the flywheel is basically determined by the size of the test tire. By the way, the larger the moment of inertia of the flywheel itself, the smaller the rotational fluctuations, so in principle the larger the flywheel, the better. However, if it is too large, it will interfere with the driving and braking of the vehicle to which it is attached, which is undesirable. . Therefore, it is particularly preferable that the flywheel has a moment of inertia within a range of 50% to 200% of the moment of inertia of the test tire.

For example, for a 185/70-13 size tire and wheel assembly, its moment of inertia is approximately 0.07
Kgm.s ² , so for example a flywheel with a moment of inertia equivalent to 100% of that has a density of 7.9
g/cm ³ iron with a radius of 23 cm when the width of the iron ring is 2 cm.

The function of the flywheel is to use its moment of inertia to cause the test tires to rotate smoothly, thereby reducing fluctuations in load due to uneven road surfaces and changes in the slip rate due to changes in the coefficient of friction of the road surface, thereby reducing the friction between the two test tires. The objective is not to cause a significant difference in wear, and furthermore, to provide stable test results in both low-speed tests under low slip conditions and low-speed tests near the maximum frictional force.

In such a configuration, in the direction of the arrow (Fig. 4)
When the test vehicle 1 is run on
Since the axle 9 and the vehicle 10 are connected by a chain through sprockets having different numbers of teeth and different diameters, they rotate with a certain rotational speed difference. As a result, relative slip occurs between the tires and the road surface, causing the axle 7 of the large diameter sprocket to
The test tires 11 and 14 mounted on the axles 8 and 9 of the small diameter sprocket are in a braking state, and at the same time, the test tires 12 and 13 mounted on the axles 8 and 9 of the small diameter sprocket are in a driving state and their wear is forcibly accelerated. It is. To explain this point in more detail with reference to FIG. 4, the speed of the test vehicle is V, the tension of the chain 18 is T, the braking force generated on the test tire 11 is f ₁ , and the driving force generated on the test tire 12 is f ₂ ,
When the radius of the test tire is R, the slip ratios S ₁ and S ₂ of the test tire 11 and the test tire 12 are the radii r ₁ and r ₂ of each sprocket 16 and 17 as shown below.
Determined by

f ₁ R = Tr ₁ ... f ₂ R = Tr ₂ ... f ₁ / f ₂ = r ₁ / r ₂ ... If the rotational speed of axles 6 and 7 is W ₁ and W ₂ , then r ₁ W ₁ = r ₂ W ₂ ... The braking force f ₁ and the driving force f ₂ are f ₁ = kS ₁ = k (V-2πRW ₁ )/V (k: constant) f ₂ = kS ₂ = k (2πRW ₂ - V )/V... From W ₁ = r ₂ (r ₁ + r ₂ )/2πR (r ₁ ² + r ₂ ² )V W ₂ = r ₁ (r ₁ + r ₂ )/2πR (r ₁ ² + r ₂ ² )V Therefore, Slip becomes S ₁ = 1-r ₂ (r ₁ + r ₂ )/(r ₁ ² + r ₂ ² ) S ₂ = 1-r ₁ (r ₁ + r ₂ )/(r ₁ ² + r ₂ ² ) .

For example, when r ₁ =100 and r ₂ =96, S ₁ =0.0208 (braking) S ₂ =0.0200 (driving). This slip rate is always stabilized due to the added inertia effect of the flywheel, even when driving at low speeds, under high slip conditions, and when there are uneven road surfaces or changes in the coefficient of friction. This prevents new wear and tear from occurring.

In the above case, in order to accelerate the wear, it is possible to increase the difference in the number of teeth between each sprocket to increase the difference in rotation speed between the two adjacent tires, but a particularly preferable rotation speed difference is about 3. % to 1%.

The test tires attached to the axle with a large diameter sprocket and the test tires attached to the axle with a small diameter sprocket generate different forces (braking force and driving force) as described above, so in actual driving, each axle is tested. It is necessary to change the positions of tires at intervals of a certain distance traveled (for example, 200 to 500 km in the case of motorcycle tires) so that the wear conditions are the same.

In the above embodiment, the connection mechanism was a chain system combining sprockets of different diameters and a chain, but instead of this, as shown in FIG. Gear 30, 3
1, or as a similar example, a known method that connects two differentials (not shown) with different reduction ratios, or two cone 32 gears as shown in FIG. , 33 connected by a belt 34, a known belt continuously variable transmission system, a known liquid coupling (not shown), etc. can be used.

In the above embodiment, two pairs of test tires are run at the same time, but of course two or more pairs may be used.Furthermore, three pairs of test tires may be run in a chain system, for example, with three different numbers of teeth. A chain may be attached to the sprocket so that each tire has a rotational step.

As in the above example, the test tire mounted on the left side and the test tire mounted on the right side are uncoupled from each other using a known independent suspension mechanism of a vehicle, and each rotates independently while adding inertia. In a configuration in which each test tire adjacent to the front and rear of each side is connected by a connecting mechanism such as the above-mentioned chain system to give each tire a desired rotational speed difference, Since the test tire group on the left side and the test tire group on the right side can have different rotational speed differences from each other, there is an advantage that different types of accelerated wear tires can be obtained at the same time. In addition, in this independent rotation running method of test tires on the left and right sides, only the group of test tires on either side is rotated at the desired rotation speed difference using the above-mentioned coupling mechanism, and while adding inertia, It is also possible to rotate the test tires on the other side and allow the test tires on the other side to rotate at the same normal rotation speed.

The test vehicle of the present invention is of a type in which the test tire is attached to the frame of the test vehicle shown in FIG. 1, but is not shown, and the vehicle equipped with the test tire is made into an independent trailer and towed by a towing vehicle. may also be used.

(Operations and Effects of the Invention) As described above, the present invention allows at least two pairs of test tires installed on a test vehicle to be driven on an actual road with a desired difference in rotational speed and by connecting the flywheel to the rotation system to smooth rotation. Since a large number of test tires of many types can be obtained at the same time in a short time and by a small number of people, efficiency is greatly improved and labor costs are reduced.

2 even when driving at low speeds, under high slip conditions, when there are uneven road surfaces and changes in the coefficient of friction.
Since there is no significant difference in wear between the test tires on the wheels, stable and highly accurate measurement and evaluation of wear performance is possible.

Ability to evaluate wear conditions due to driving and braking at the same time.

The design cost is low because there is no need for any special equipment to generate driving force and braking force in the tires.

To safely and easily accelerate wear even when a motorcycle test tire is provided with a desired slip angle or camber angle, compared to a conventional actual vehicle running system.

Less energy loss.

It has excellent effects such as:

[Brief explanation of drawings]

Figure 1 is a μ-S characteristic diagram showing variations in tire slip rate under high slip conditions, Figure 2 is a μ-S characteristic diagram showing fluctuations in tire slip rate when running at low speeds,
Fig. 3 is a plan view showing one embodiment of the apparatus (test vehicle) used to carry out the method of the present invention, Fig. 4 is a diagram explaining the principle of the method of the present invention, and Figs. 5 and 6 are other connections of the flywheel. Partial plan views showing aspects, Figures 7 and 8 are 2
FIG. 7 is a partial plan view showing another embodiment of a coupling mechanism for providing a rotational speed difference between different test tires. 1...Test vehicle, 7-10...Axle, 11-14
...Test tires, 16, 17, 20, 21...
Sprocket, 18, 22...Chain, 19,
23... Connection mechanism, 24-27, 35, 36...
Flywheel, 37...wheel for tires.

Claims (1)

[Claims] 1. At least two pairs of test tires are mounted on a test vehicle, and each test tire adjacent to the front and back on the left side or the right side is rotated at different rotation speeds while adding inertia. A method for running a tire on an actual road wear test, which is characterized by driving on an actual road. 2. The moment of inertia to be added is 50% to 200% of the moment of inertia of the tire/wheel assembly.
A method for running a tire on an actual road wear test according to claim 1. 3. A test vehicle, at least two pairs of test tires rotatably mounted on the test vehicle, an inertia addition mechanism connected to the rotation system, and each test tire adjacent to the front and back on the left side or right side of A tire actual road wear test running device comprising a connecting mechanism connected to rotate at a rotational speed.