KR102473567B1 - Test method for hydroplaning of pneumatic tire - Google Patents

Abstract

The present invention relates to a tire aquaplaning test method for evaluating the drainage of a pneumatic tire by testing the aquaplaning of the pneumatic tire on a straight section.
In the tire aquaplaning test method according to the present invention, the vehicle in a no-slip state on a coordinate plane with the speed of the vehicle 1 as the x-axis and the number of revolutions (RPM) of the tire 2 as the y-axis A no-slip line setting step (S110) of setting a no-slip line (y ₀ ), which is a relationship between the speed of (1) and the number of revolutions (RPM), and the no-slip line (y ₀ ) in the y-axis direction by the slip ratio A shift line setting step (S120) of setting the moved shift line ( _{15%, slip} ), and driving the vehicle 1 at a plurality of preset entry speeds (V _{n, start} ) in the water curtain section, and the water curtain section The vehicle driving step (S130) of measuring the exit speed (V _n,end ) at the end point, and the difference between the entry speed (V _n,start ) and the exit speed (V _n,end ) of the tire (2 ) and a rotation speed compensation step (S140) of obtaining a compensated number of rotations (RPM _n,hydro ) compensated for the number of revolutions (RPM) of the tire 2 upon entry (S140), and the entry speed (V _n For each _,start ), the compensated rotation number (RPM _n,hydro ) obtained in the rotation speed compensation step (S140) and the corresponding entry speed (V _n,start ) are displayed on the coordinate plane, respectively, and the test line connecting them (y _test ), and determining the speed at the point where the shift line ( _{15%, slip} ) and the test line (y _test ) are the same on the coordinate plane as the slip speed (V _k ) A slip speed acquisition step (S160) is included.

Description

Tire aquaplaning test method {TEST METHOD FOR HYDROPLANING OF PNEUMATIC TIRE}

The present invention relates to a tire aquaplaning test method for evaluating the drainage of a pneumatic tire by testing the aquaplaning of the pneumatic tire on a straight section.

Among the methods for evaluating the performance of pneumatic tires (hereinafter referred to as 'tires'), there is a hydroplaning in straight test as a method for evaluating the drainage of the tire.

The linear aquaplaning test is evaluated by measuring the slip generated in the tire 2 by running on a road surface formed with a water depth at a predetermined depth (D). While accelerating and driving the vehicle 1 equipped with the tire 2 in a water curtain section set to a predetermined length L, the actual vehicle speed and the wheel speed of the tire 2 are compared to obtain a slip rate at a predetermined ratio, for example, The vehicle speed is measured when the slip ratio is 15%.

That is, as shown in FIG. 1, while accelerating the vehicle 1 on the water curtain section, the vehicle speed at the time point A when the slip ratio reaches 15% is measured.

Here, the slip rate is calculated by the following formula.

A tire with good drainage exhibits a high vehicle speed with the slip ratio of 15%.

However, in this prior art straight aquaplaning test, a wheel speed sensor for measuring the rotational speed of the tire 2 must be installed in order to calculate the slip ratio of the tire 2.

Since the wheel speed sensor is essential, whenever the tire 2 for the test is replaced in the vehicle 1, it is inconvenient to newly install the wheel speed sensor on the tire.

In addition, since the conventional linear aquaplaning experiment is measured during acceleration, it is suitable for the front wheel test, but the rear wheel has a problem in that the depth of the water film decreases as the water film is dispersed by the front wheel, so that the actual water film section cannot be formed.

JP2000-249628 A (2000.09.14, name: evaluation method and apparatus for hydroplaning resistance)

The present invention was invented to solve the above problems, and an object of the present invention is to provide a tire aquaplaning test method capable of evaluating the drainage of a pneumatic tire in an aquaplaning section without installing a wheel speed sensor.

In the tire aquaplaning test method according to the present invention for achieving the above object, the slip between the tire and the road surface is determined in the coordinate plane with the vehicle speed as the x-axis and the tire rotation speed as the y-axis. A no-slip line setting step of setting a no-slip line, which is a relationship between the speed of the vehicle and the number of revolutions in a non-slip state, and a shift line in which the no-slip line is moved in the y-axis direction by a predetermined slip ratio on the coordinate plane a shift line setting step of setting, a vehicle driving step of driving the vehicle at a plurality of preset entry speeds in a water curtain section and measuring an exit speed at a point where the water curtain section ends, and the entry speed and the exit speed A rotation speed compensation step of obtaining the compensated rotation speed of the tire by converting the difference in r to the rotation speed of the tire and compensating for the rotation speed of the tire when entering the water film section, and obtained in the rotation speed compensation step for each entry speed A test line acquisition step of displaying the compensated number of rotations and the corresponding entry speed on a coordinate plane, respectively, and acquiring a test line connecting points marked on the coordinate plane; and a slip speed acquisition step of determining a speed at a losing point as a slip speed.

The no-slip line is characterized in that it is set according to the standard of the tire.

, (A : 타이어의 직경), 상기의 식으로부터 구해지는 것을 특징으로 한다.The rotational speed of the tire is

, (A: tire diameter), characterized in that it is obtained from the above formula.

The diameter of the tire is characterized in that it is determined from the standard of the tire.

, (W : 타이어의 단면폭, K : 편평비, H : 타이어의 단면높이). 상기의 식으로부터 결정되는 것을 특징으로 한다.The diameter of the tire is

, (W: tire section width, K: aspect ratio, H: tire section height). It is characterized in that it is determined from the above formula.

The vehicle driving step is characterized in that the vehicle is repeatedly driven from the test start speed to the limit speed at preset speed intervals as an entry speed.

The vehicle driving step is characterized in that the vehicle is repeatedly driven from the test start speed of 60 km/h to the limit speed of 100 km/h at intervals of 5 km/h as an entry speed.

In the step of setting the shift line, the slip ratio is set to 15%, and the no-slip line is moved in the y-axis direction.

The vehicle driving step is characterized in that the road surface on which the water film is formed is driven at a constant speed at the entry speed.

The slip speed obtaining step may include obtaining a slip speed by reading an intersection between the shift line and the test line on the coordinate plane.

The shift line is a linear function graph, and the test line is a quadratic function graph.

In the step of acquiring the slip speed, the slip speed is calculated from a solution of an equation in which a function expression of the first-order function graph and a function expression of the second-order function graph are the same.

According to the aquaplaning test method of the tire of the present invention having the configuration as described above, since a wheel speed sensor is unnecessary for the test, the inconvenience of installing the wheel speed sensor every time a tire is replaced is improved.

In addition, as the speed decreases in the water curtain section, the drainage of the tire can be evaluated even on the rear wheels, and accordingly, the drainage of the tires mounted on the rear-wheel drive or 4-wheel drive can be evaluated.

1 is a schematic diagram showing a state in which a vehicle drives in an aquaplaning section for a hydroplaning test of a tire.
2 is a graph showing a method for obtaining a slip speed by a tire aquaplaning test method according to the prior art.
3 is a graph showing a method for obtaining a slip speed by the aquaplaning test method of a tire according to the present invention.
Fig. 4 is a schematic view showing the specifications of a tire;
5 is a graph for comparing the drainage of two different tires.
6 is a flowchart illustrating a method for testing aquaplaning of a tire according to the present invention.

Hereinafter, a method for testing aquaplaning of a tire according to the present invention will be described in detail with reference to the accompanying drawings.

In the aquaplaning test method of a tire according to the present invention according to the present invention, the tire ( 2) a no-slip line setting step (S110) of setting a no-slip line (y ₀ ), which is a relationship between the speed of the vehicle 1 and the number of revolutions (RPM) in a state in which slip is not between the road surface and the A shift line setting step (S120) of setting a shift line ( _{15%, slip} ) by moving the no-slip line (y ₀ ) in the y-axis direction by a predetermined slip ratio on the coordinate plane, and a plurality of previously set A vehicle driving step (S130) of driving the vehicle 1 at the entry speed (V _n,start ) and measuring the exit speed (V _n,end ) at the point where the water curtain section ends;

The difference between the entry speed (V _n,start ) and the exit speed (V _n,end ) is converted into the number of revolutions of the tire 2, and the number of revolutions (RPM) of the tire 2 is compensated when entering the water film section. Thus, the rotation speed compensation step (S140) of obtaining the compensated rotation speed (RPM _{n, hydro} ) of the tire 2, and the rotation speed compensation step (S140) for each entry speed (V _{n, start} ) obtained A test line acquisition step of displaying the compensated number of revolutions (RPM _n,hydro ) and the corresponding entry speed (V _n,start ) on the coordinate plane, respectively, and obtaining a test line (y _test ) connecting points marked on the coordinate plane. (S150) and a slip speed acquisition step (S160) of determining the speed at the point where the shift line ( _{15%, slip} ) and the test line (y _test ) are the same as the slip speed (V _k ) on the coordinate plane. include

In the no-slip line setting step (S110), the no-slip line (y ₀ ) is set.

On a coordinate plane with the speed of the vehicle 1 as the x-axis and the number of revolutions of the tire 2 as the y-axis, assuming a state in which the tire 2 does not slip, the vehicle 1 The relationship between the speed and the rotational speed of the tire 2 is shown.

If slip does not occur between the tire 2 and the road surface, the speed of the vehicle 1 and the linear speed around the tire 2 are equal.

In addition, if the number of revolutions of the tire 2 is known in a state where the standard of the tire 2 is known, the linear speed around the tire 2 can be obtained. By this relationship, the number of rotations of the tire 2 according to the speed of the vehicle 1 in a no-slip state can be obtained.

That is, the standard of the tire 2 is indicated by the section width (mm), aspect ratio, and wheel diameter (inch), such as '205/55R16', and through this, the diameter (A) of the tire 2 can be obtained. . In FIG. 4 , the diameter A of the tire 2 is as follows.

A = (H × 2 + I)

Here, A is the diameter of the tire 2, H is the sectional height of the tire 2, and I is the diameter of the wheel on which the tire 2 is mounted.

On the other hand, since the aspect ratio (K) of the tire 2 is 'K=W/H × 100', the cross-section height (H) of the tire 2 is 'H = (W × K/100) ( W: cross section width of tire, K: aspect ratio, H: cross section height of tire).

Therefore, when the diameter A of the tire 2 is converted into an expression related to the standard of the tire 2,

Here, '25.4' multiplied by the diameter (I) of the wheel is to convert inches to mm.

The relationship between the number of rotations (RPM) of the tire 2 and the diameter of the tire 2 is as follows.

Since the speed V of the vehicle becomes 'V = πA/t' and the time t and the number of rotations (RPM) of the tire 2 are inverse, the above relationship is established.

Normally, the speed of a vehicle is expressed in 'km/h', so converting it into meters is as follows.

Here, '16.67' multiplied by the speed of the vehicle is a number for converting 'km/h' to 'm/min', and '0.001' is for converting mm to m.

When the number of revolutions (RPM) of the tire 2 rotates, the linear speed around the tire 2 can be known.

According to this relationship, the relationship between the speed of the vehicle 1 and the number of revolutions of the tire 2 is obtained under the assumption that the tire 2 does not slip on the coordinate plane.

In the shift line setting step (S120), a shift line (y _{15%, slip} ) obtained by moving the no-slip line (y ₀ ) in the y-axis direction by a predetermined slip ratio is set on the coordinate plane.

When the tire 2 slips due to the water film on the road surface, the number of revolutions (RPM) of the tire 2 increases compared to the speed of the vehicle 1, so the no-slip line y ₀ is set to ' By moving in the +y' direction, the shift line ( _{15%, slip} ) is set.

Here, by setting the slip ratio to 15%, the shift line ( _{15%, slip} ) is set by moving the no-slip line (y ₀ ) by 15% in the y-axis direction.

Here, by setting the slip ratio to 15%, the shift line ( _{15%, slip} ) is set by moving the no-slip line (y ₀ ) by 15% in the y-axis direction.

In the vehicle driving step (S130), the vehicle 1 is driven on the road surface on which the water film is formed at a preset entry speed (V _n,start ) at different speeds.

In the vehicle driving step (S130), the road surface on which the water film is formed is driven at a constant speed at the entry speed (V _n,start ). In the prior art, the vehicle was accelerated and driven on the road surface on which the water film was formed, but in the present invention, the vehicle is driven at constant speed on the road surface on which the water film is formed. Since the vehicle 1 is driven at a constant speed without accelerating, the speed of the vehicle 1 is substantially reduced by the water film in the water film section, and the phenomenon in which the water film is dispersed by the front wheels is reduced. The drainage of the tire can also be evaluated.

In the present invention, after the vehicle 1 drives the water curtain section by entering the vehicle 1 at a preset entry speed (V _n,start ) with respect to the road surface on which the water curtain is formed, that is, the water curtain section, Measure the advance velocity (V _n,end ) at the end point. By varying the entry speed (V _n,start ), the entry speed (V _n,start ) and the exit speed (V _n,end ) in the water film section are measured. At this time, the vehicle 1 varies the entry speed (V _n,start ) at preset intervals to drive the water curtain section. For example, while increasing the entry speed (V _n,start ) at intervals of 5 km/h from the test start speed of 60 km/h, the entry speed (V _n,start ) is varied until the limit speed of about 100 km/h.

The water film section means a section used in an actual test among road surfaces on which a water film is formed.

In the speed compensating step (S140), the difference between the entry speed (V _n,start ) and the exit speed (V _n,end ) is converted into the number of revolutions of the tire 2, so that the speed of the tire 2 when entering the water film section is changed. It compensates for the number of revolutions (RPM).

The vehicle 1 advances through the water film section at a speed lower than the speed when entering the water film section due to the water film existing on the road surface. The difference between the entry speed (V _n,start ) and the exit speed (V _n,end ) becomes the magnitude of the drainage capacity of the tire 2 due to aquaplaning.

In the present invention, which tests the aquaplaning phenomenon without a wheel speed sensor, the difference between the entry speed (V _n,start ) and the exit speed (V _n,end ) for the aquaplaning section is converted into the number of rotations of the tire 2, Compensation added to the number of revolutions (RPM) of the tire 2 is performed.

Here, the compensated rotational speed (RPM _n,hydro ) of the tire 2 reflected in the aquaplaning can be expressed as follows.

RPM _n,hydro = RPM _n,start + (RPM _n,start - RPM _n,end )

Here, 'RPM _n,start - RPM _n,end ' is a value expressed by the number of revolutions of the tire as the speed decrease (the degree of water resistance expressed as drainage) due to the hydroplaning phenomenon.

In the test line acquisition step (S150), the compensated number of rotations (RPM _n,hydro ) obtained in the rotation speed compensation step (S140) for each entry speed (V n, _start ) and the corresponding entry speed (V _n,start ) are coordinates. Each is marked on a plane, and a test line (y _test ) connecting points marked on the coordinate plane is obtained.

As shown in FIG. 3, the test line (y _test ) is expressed as a quadratic function graph. That is, the compensated number of revolutions and the corresponding entry speed for each entry speed are displayed as X on the coordinate plane, as shown in FIG. It is obtained as a difference function graph.

In the slip speed obtaining step (S160), the slip speed of the tire 2 is obtained by reading the speed at the intersection of the shift line ( _{15%, slip} ) and the test line (y _test ).

In a state where the shift line ( _{15%, slip} ) is set on the coordinate plane, the speed at a point where the test line (y _test ) obtained through the vehicle driving step (S130) does not intersect is read.

Here, the speed at the point where the seat line ( _{15%, slip} ) and the test line (y _test ) intersect on the coordinate plane becomes the slip speed (V _K ) of the tire 2 .

Meanwhile, in the slip speed obtaining step (S160), the slip speed V _k may be calculated by calculation.

라 하고, 15%로 슬립되는 것으로 상기 시프트라인(_15%,slip)을 설정한다면,

라 한다면, 'y_(test) = y_(15%,slip)'일 때, 슬립속도(V_k)를 얻는다.The function expression of the test line (y _test )

, and if the shift line ( _{15%, slip} ) is set to slip at 15%,

, when 'y _(test) = y _(15%,slip) ', the slip speed (V _k ) is obtained.

If 'y _(test) = y _{(15%, slip)} ' and the term theorem is performed, the following quadratic equation can be obtained.

As the solution of the quadratic equation becomes the slip speed (V _k ), the slip speed (V _k ) is obtained as follows.

That is, the slip speed V _k may be calculated from a solution of an equation set so that the function expression of the shift line ( _{15%, slip} ) and the function expression of the test line (y _test ) are the same.

Meanwhile, in the shift line setting step (S120), the slip ratio was set to 15% to obtain the slip speed (V _k ) as described above. If this is generalized, the slip speed (V _k ) can be obtained as follows have.

에 상기 테스트라인이 통과하는 지점의 값을 대입하여 구해진다.Here, a and b can be known by tire specifications, and α, β, and γ can calculate the value of the quadratic function graph by testing, and the slip speed (V _k ) can also be calculated by calculation. can That is, a and b are coefficients and constants of the no-slip line (y ₀ ), which is a linear function, α and β are coefficients of a graph of a quadratic function obtained by a test, and γ is a graph of a quadratic function obtained by a test. is a constant, and k is the slip ratio. The above α, β, γ are

It is obtained by substituting the value of the point through which the test line passes.

5 shows an example of aquaplaning test results for two tires 2 .

The table below shows an example of the results of calculating the slip speed (V _k ) for two tires A and B with the same tire specification of '205/55R16' and different drainage performance by the method described above. 1 and Table 2.

tire
A Entry velocity (V _n,start ) Advance velocity (V _n,end ) Compensated RPM
(RPM _{n, hydro} ) Slip speed (km/h)
15% slip Vehicle speed (km/h) RPM (no slip) Vehicle speed (km/h) RPM (slip) 60.1 504.6 60.0 503.7 505.4


78.1 65.4 549.1 64.8 544.0 554.1 70.2 589.4 68.6 575.9 602.8 75.2 631.3 72.4 607.8 654.9 80.6 676.7 76.4 641.4 711.9 85.4 717.0 79.2 664.9 769.0 90.2 757.3 81.4 683.4 831.2

tire
B Entry velocity (V _n,start ) Advance velocity (V _n,end ) Compensated RPM
(RPM _{n, hydro} ) Slip speed (km/h)
15% slip Vehicle speed (km/h) RPM (no slip) Vehicle speed (km/h) RPM (slip) 60.2 505.4 60.1 504.6 506.3


82.6 65.4 549.1 65.2 547.4 550.7 70.2 589.4 69.2 581.0 597.8 75.6 634.7 73.5 617.1 652.3 80.4 675.0 77.5 650.7 699.4 85.4 717.0 80.7 677.5 756.4 90.1 756.4 83.1 697.7 815.2

The slip rate was set to 15%, and the slip speed (V _k ) of tire A and tire B was obtained by varying the entry speed (V _n,start ) from about 60 km/h to about 90 km/h at intervals of about 5 km/h. As a result, the slip speed of tire A is 78.1 km/h and the slip speed of tire B is 82.6 km/h.

From this result, it can be seen that tire B has better drainage performance because it has better driving performance in the water curtain section.

1: vehicle
2 : tire
S110: No-slip line setting step
S120: Shift line setting step
S130: vehicle driving step
S140: RPM compensation step
S150: Test line acquisition step
S160: Slip speed acquisition step

Claims (12)

Set a no-slip line that is the relationship between the speed of the vehicle and the number of revolutions in a state where the vehicle speed is the x-axis and the number of revolutions of the tire is the y-axis in a coordinate plane in which there is no slip between the tire and the road surface A no-slip line setting step to do;
A shift line setting step of setting a shift line obtained by moving the no-slip line in the y-axis direction by a predetermined slip ratio on the coordinate plane;
A vehicle driving step of driving the vehicle at a plurality of preset entry speeds in a water curtain section and measuring an exit speed at a point where the water curtain section ends;
A rotation speed compensating step of converting the difference between the entry speed and the exit speed into the rotation speed of the tire, and compensating for adding the difference to the rotation speed of the tire when entering the water film section to obtain the compensated rotation number of the tire; ,
A test line acquisition step of displaying the compensated number of revolutions obtained in the revolution speed compensation step and the corresponding entry speed for each entry speed on a coordinate plane, and acquiring a test line connecting points marked on the coordinate plane;
and a slip speed acquisition step of determining, as a slip speed, a speed at a point where the shift line and the test line are identical on the coordinate plane. According to claim 1,
The method for testing aquaplaning of a tire, characterized in that the no-slip line is set according to the standard of the tire. According to claim 2,
The rotational speed of the tire is

(V: vehicle speed, A: tire diameter),
A method for testing aquaplaning of a tire, characterized in that it is obtained from the above formula. According to claim 3,
The diameter of the tire is
A method for testing aquaplaning of a tire, characterized in that determined from the specifications of the tire. According to claim 4,
The diameter of the tire is

(W: tire section width, K: aspect ratio, H: tire section height, I: wheel diameter),
A method for testing aquaplaning of a tire, characterized in that it is determined from the above formula. According to claim 1,
In the vehicle driving step,
A method for testing aquaplaning of a tire, characterized in that the tire is driven repeatedly from the test start speed to the limit speed at a preset speed interval as an entry speed. According to claim 6,
In the vehicle driving step,
A hydroplaning test method of a tire, characterized in that the tire is driven repeatedly from the test start speed of 60 km/h to the limit speed of 100 km/h at intervals of 5 km/h as the entry speed. According to claim 1,
In the step of setting the shift line,
A method for testing aquaplaning of a tire, characterized in that the slip ratio is set to 15% and the no-slip line is moved in the y-axis direction. According to claim 1,
The method for testing aquaplaning of a tire, characterized in that in the vehicle driving step, the road surface on which the water film is formed is driven at a constant speed at the entry speed. According to claim 1,
In the step of obtaining the slip speed,
A method for testing aquaplaning of a tire, characterized in that the slip speed is obtained by reading an intersection of the shift line and the test line on the coordinate plane. According to claim 1,
The shift line is a linear function graph,
The test line is a quadratic function graph,
The test line displays the compensated number of revolutions and the corresponding entry speed for each entry speed on a coordinate plane, and connects the points displayed on the coordinate plane with a quadratic function to obtain a graph of the quadratic function. Characterized in that Tire aquaplaning test method. According to claim 11,
In the step of obtaining the slip speed,
The slip speed is calculated from the solution of the following equation in which the function expression of the first-order function graph and the function expression of the second-order function graph are the same,
The function expression of the quadratic function graph is the value of the point where the test line passes

A method for testing aquaplaning of a tire, characterized in that obtained by substituting

(V _k : slip speed, α, β: coefficient of the quadratic function graph obtained by the test, γ: constant of the quadratic function graph obtained by the test, k: slip ratio, a: of the no-slip line (y ₀ ) coefficient, b: constant of the no-slip line)

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