JP4119585B2 - High-speed tire uniformity measurement method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tire high-speed uniformity measurement method, and more particularly to a tire high-speed uniformity measurement method capable of measuring a tire high-speed uniformity in a short time.
[0002]
[Prior art and problems to be solved by the invention]
The tire uniformity generated when a load is applied to the tire and the vehicle rolls straight with a constant rolling radius includes the load (vertical force) fluctuation component RFV (radial force variation) and the longitudinal force fluctuation component TFV ( Tangential force variation), lateral force fluctuation component LFV (lateral force variation), radial run-out (RRO) which is a vertical pitch of the tire in the radial direction, and the like.
[0003]
The measuring method of the low speed uniformity is defined in JASO C 607-87, and the low speed uniformity is generally measured at a constant speed (rotational speed 60 rpm). Further, since the low speed uniformity is not affected by the residual unbalance, it is not necessary to measure the residual unbalance.
[0004]
On the other hand, with respect to the high-speed uniformity, there is no provision for the measurement method, but the measurement is generally performed at a constant speed (rotation speed of 60 rpm or more). In the analysis of high-order components of high-speed uniformity, resonance phenomenon with other characteristics of the tire (natural frequency, cavity resonance frequency, etc.) occurs, so it is common to measure by tracking analysis method with varying speed It is.
[0005]
In addition, because the primary component of the high-speed uniformity is affected by residual imbalance, it is necessary to measure the residual imbalance separately from the high-speed uniformity and evaluate the data by removing the residual unbalance measurement value from the high-speed uniformity measurement value. There is.
[0006]
As for the measurement method of this residual unbalance, there are a method of rotating the tire by inertia from above the target speed under no load, and a high speed TFV of the target speed by skim touch (the last load where the tire touches the ground). There are two types, a method of using this high-speed TFV as a substitute value for residual unbalance.
[0007]
However, when measuring high-speed uniformity, the speed is not measured when the speed is increased from when the tire is stopped until it reaches the target rotational speed, and when the speed is decreased from the target rotational speed until it stops. Since the measurement is performed in a maintained state, depending on the ability of the testing machine, there is a problem that generally the measurement takes a long time.
[0008]
In addition, when analyzing the primary component of high-speed uniformity, it is necessary to measure the residual unbalance, and it is necessary to measure the residual unbalance with no load or with a skim touch. There is a problem that it takes a long time for the measurement.
[0009]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a tire high-speed uniformity measuring method capable of measuring high-speed uniformity in a short time.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 measures the high speed uniformity in a state where a load is applied to the tire and the rotational speed of the tire is changed in the first direction, and the load is applied to the tire. A state in which the rotation speed of the tire is not changed and the rotation speed of the tire is changed in a second direction different from the first direction, or a load immediately before contact with the tire is applied, and the rotation speed of the tire is the second speed The residual imbalance is measured in the state of changing in the direction, and the primary component of the high speed uniformity is measured by subtracting the measurement value of the residual unbalance from the measurement value of the high speed uniformity.
[0011]
In the first aspect of the invention, the high speed uniformity is measured in a state where a load is applied to the tire and the rotational speed of the tire is changed in the first direction (upward or downward). Since the primary component of the high-speed uniformity has the effect of residual imbalance, the load is not applied to the tire and the tire rotation speed is in the second direction (when the first direction is the upward direction) separately from the high-speed uniformity Is in the downward direction, the upward direction when the first direction is the downward direction), or the load immediately before contact with the tire is applied, and the rotational speed of the tire changes in the second direction. In this state, the residual imbalance is measured, and the primary imbalance component is measured by subtracting the residual unbalance measurement value from the high speed uniformity measurement value.
[0012]
When measuring the primary component of the high-speed uniformity, if you attempt to measure the high-speed uniformity and residual imbalance within one cycle when the rotational speed increases and decreases, the measurement timing cannot be obtained, so the measurement speed range is within the specified rotational speed. High speed uniformity and residual imbalance will be measured.
[0013]
Further, the residual imbalance Generally imbalance m on the tire circumferential Consider the case rotating at angular velocity ω with radius r rolling tires, it can be represented by Mromega ^2, the rotational speed and the residual unbalance This relationship can be represented by a substantially quadratic regression curve. Therefore, based on the high-speed uniformity at an arbitrary rotational speed, the residual unbalance corresponding to the arbitrary speed is estimated from the quadratic regression curve, and the residual unbalance is vector-subtracted from the high-speed uniformity at each arbitrary rotational speed, and the residual The primary component of high-speed uniformity corrected by balance is measured.
[0014]
In the first aspect of the invention, the high-speed uniformity of the tire is measured in a state where the rotational speed of the tire is changing in the first direction, and the residual unbalance is measured in the state where it is changing in the second direction. Therefore, it is possible to measure while the tire rotates from the stop state and returns to the stop state, and it is not necessary to keep the tire rotation speed constant, so the primary component of the tire high speed uniformity can be measured in a short time. Can do.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail. First, a testing machine used in the present embodiment will be described with reference to the drawings. As shown in FIG. 1, the testing machine includes a drum 18 connected to a motor 16 via gear couplings 10 and 12 and a gear box 14. A rotation speed sensor for detecting the rotation speed of the drum rotated by the motor 16 is attached to the drum 18. The rotational speed sensor includes a signal rotor 20A fixed to the shaft of the drum 18 and a photo interrupter 20B arranged so as to sandwich the teeth of the signal rotor 20A. In the vicinity of the gear box 18, a dedicated tire attachment stand 22 is disposed so as to be movable via shafts 22 </ b> A and 22 </ b> B by a hydraulic device 30 connected to a hydraulic cylinder 28.
[0016]
On the top of the dedicated stand 22 is a 6-minute load cell that detects force fluctuations in the x, y, and z-axis directions (three directions in the vertical direction, front-rear direction, and left-right direction of the tire) and moments around each axis. A force meter (Kistler) 24 is attached, and a measured tire 26 is rotatably attached to the six-component force meter 24. With this 6-component force meter, the tire vertical axial force Fz, the tire longitudinal axial force Fx, and the tire lateral axial force Fy are detected.
[0017]
The hydraulic cylinder 28 is connected to a hydraulic pressure generator 32 via a hydraulic pipe. The hydraulic pressure generator 32 is connected to an electromagnetic valve 34 connected to an air source, and the magnitude of the hydraulic pressure generated by controlling the switching of the electromagnetic valve 34 is controlled. Reference numeral 36 denotes a pressure gauge that detects the pressure at the contact point between the tire and the drum.
[0018]
As shown in FIG. 2, the 6-component force meter 24, the photo interrupter 20B of the rotational speed sensor, the motor 16, and the electromagnetic valve 34 are connected to a personal computer 42 to which a CRT 38 as a display device for displaying measurement data and the like is connected. Has been. The personal computer 42 is connected to an input device 40 for designating a rotation speed of a high-speed uniformity to be displayed and inputting a command or the like.
[0019]
Next, the measurement method of the present embodiment, that is, the case where the above-described measuring machine is used, the tire is rotationally driven by driving on the drum side, and the detection of the tire axial force is detected by the tire axial side 6 component force meter A measurement routine executed by the personal computer will be described with reference to FIG. In the following, a case where the primary component of the high-speed uniformity is measured will be described.
[0020]
In step 100, the electromagnetic valve 34 is controlled, and the measured tire 26 is pressed against the side surface of the drum 18 with a predetermined pressure by the hydraulic device 30 to load the measured tire 26. In step 102, the measured tire 26 is loaded. The drum 18 starts rotating in a state where the load is applied, and the motor 16 is controlled based on the output of the photo interrupter 20B, thereby increasing the rotational speed of the drum at a constant rate.
[0021]
In step 104, based on the output of the photo interrupter 20B, it is determined whether or not the rotational speed has increased by a predetermined rotational speed, so that it is determined whether or not the predetermined measurement timing has been reached. In step 106, the output of the 6-component force meter 24 is fast Fourier transformed to calculate the amplitude corresponding to the primary component of the high-speed uniformity corresponding to the rotational speed of the measurement timing and the phase corresponding to the primary component. Measure high speed uniformity.
[0022]
Note that when calculating the amplitude and phase, an event trigger device that outputs one pulse per rotation of the tire is attached to the tire rotation axis, so the phase is calculated based on the generated pulse position. In addition, tracking analysis is performed using this trigger pulse. The trigger pulse does not need to be one pulse per rotation, and the accuracy increases as the number increases. Alternatively, one pulse may be multiplied to several tens of pulses.
[0023]
In step 108, it is determined whether or not a predetermined maximum speed (predetermined value of 60 rpm or more) has been reached. If the maximum speed has not been reached, the above measurement is repeated for each predetermined rotational speed, and the maximum speed has been reached. By the way, the measurement of high-speed uniformity is finished. Thus, by measuring the high speed uniformity every time the rotation speed increases by a predetermined rotation speed, the high speed uniformity is measured for each predetermined rotation speed.
[0024]
After the high-speed uniformity measurement is completed, the solenoid valve 34 is controlled in step 110 to control the tire to skim touch the drum side surface, thereby applying a load immediately before the tire touches the tire and regenerating the motor. By operating, the drum rotation speed is decreased at a constant rate. The skim touch may be controlled by the operator operating the input device 40 while viewing the pressure gauge, or may be automatically controlled. Further, the rotation speed may be lowered by inertia.
[0025]
Fast Fourier transform of 6-component force meter output at step 114 with the timing when the rotation speed (or frequency) set in advance at step 112 is reached while the load immediately before the tire touches the tire is measured. As a result, the amplitude and phase of the residual unbalance are measured. Since the measurement of the residual imbalance is continued until it is determined in step 116 that the measurement is completed, the residual imbalance is measured at every predetermined rotation speed (or every predetermined frequency).
[0026]
If it is determined in step 116 that the measurement of the residual imbalance has been completed, then in step 118, the relationship between the measured value of the residual imbalance and the rotational speed at the time of measurement is determined from the measured value of the residual imbalance and the rotational speed. A secondary regression curve is obtained, and each residual imbalance corresponding to each rotational speed at which the high-speed uniformity is measured is estimated from the secondary regression curve obtained. Next, the primary component of the high-speed uniformity corrected by the residual unbalance is calculated by vector subtracting the residual unbalance from the high-speed uniformity at each rotational speed. Then, the high speed uniformity corresponding to the rotation speed designated by the input device 40 is interpolated from the plurality of values of the high speed uniformity after the residual unbalance correction for each predetermined speed obtained within the measurement speed range, and the calculated high speed The primary component of uniformity is displayed on the CRT.
[0027]
FIG. 4 shows the correlation between the measured values (x-axis) of the primary components of the RFV and TFV with or without residual unbalance correction and the measured values of the tracking method of the present embodiment. As can be seen from the figure, the correlation coefficient is high and this embodiment has a high correlation with the measured value at a constant speed.
[0028]
5 and 6 show the correlation between the measured values of RFV and TFV at a constant speed and the measured values of the present tracking method in each order (first to tenth). In each figure, the horizontal axis represents the measured value of the constant velocity method, and the vertical axis represents the measured value of the tracking method. As understood from the figure, the present embodiment has a high correlation with the measurement value at a constant speed even in each order, and when the speed is designated, the data of each order component of the designated speed is obtained. Can be measured.
[0029]
In the above description, the example of measuring the residual imbalance in a state where a skim touch, that is, a load immediately before the tire touches the ground is described, but the tire is separated from the drum and the tire and the drum are not in contact with each other. In other words, the residual unbalance may be measured while the tire load is in a no-load state and the tire rotational speed decreases due to inertia. In this case, since the tire rotates with inertia, it takes more time for the rotation to stop than when the descent speed of the tire is controlled while decreasing the rotation speed of the drum with skim touch.
[0030]
In the above example, the high speed uniformity is measured when the speed is increased and the residual imbalance is measured when the speed is decreased. Conversely, the residual unbalance is measured by skim touch when the speed is increased, and the high speed uniformity is measured when the speed is decreased. You may make it measure.
[0031]
Next, a measurement method for measuring high-speed uniformity using a measuring machine that drives a tire with a motor on the tire shaft side and detects tire axial force with a six-component force meter on the tire shaft side will be described.
[0032]
First, in the same manner as described above, the tire is pressed against the drum, the rotational speed is increased in a state where a load is applied to the tire, and the high speed uniformity is measured at each predetermined rotational speed in the middle of the speed increase.
[0033]
When the maximum speed is reached, the tire is separated from the drum, the tire load is set to a no-load state, and the residual unbalance is measured at each predetermined rotational speed in the same manner as described above while the speed of the tire decreases due to inertia. In this case, since the tire is driven on the tire shaft side, it is possible to control the lowering speed of the tire by the regenerative operation of the motor even when the tire load is not loaded.
[0034]
In the above-described measuring machine that drives the tire shaft side, an example has been described in which the high speed uniformity is measured when the speed is increased, and the residual imbalance is measured when the speed is decreased. The unbalance may be measured, and the high speed uniformity may be measured when the speed decreases. However, when measuring high-speed uniformity, the tire that is rotating at the maximum speed is brought into contact with the drum that is stopped and a load is applied to the tire, so the frictional force of the tire rises rapidly and damages the tire. Concerned about giving. To solve this problem, measure the residual unbalance while rotating the drum with skim touch when the speed increases, and load the tire while the drum and tire are rotating at the same maximum speed. What is necessary is just to measure a high-speed uniformity.
[0035]
In the above, the example of measuring the primary component of the high-speed uniformity has been described, but the high-order component of the high-speed uniformity can also be measured when the speed increases or decreases. Even when measuring higher-order components, the same timing as measuring the first-order components, the measurement timing of high-speed uniformity cannot be taken within one cycle of ascending or descending, but there is no influence of residual imbalance on the higher-order components. There is no need to measure the residual unbalance, and the high-speed uniformity can be adopted without correction.
[0036]
In addition, if there is a resonance peak due to the tire eigenvalue, if the peak value of the amplitude within the measurement speed range is obtained, it has been experimentally known that it corresponds well to the actual phenomenon, so the eigenvalue of the tire can also be measured easily. Can do.
[0037]
It has been confirmed by experiments that the correlation coefficient is 0.9 or more and the correlation with the measured value at a constant speed is good even when measuring high-order components of high-speed uniformity.
[0038]
Next, conditions for analysis by the tracking method of the present embodiment will be described. Depending on the capacity of the measuring device, if there is a measuring device that can control 20 to 120 km / h in about 30 seconds, the data analysis is 400 lines and the anti-aliasing filter characteristics are Assuming fs · 0.39, the result is as follows.
[0039]
{Circle around (1)} When the processing of one line measures 16 waveforms at fs = 64 points / waveform (1024 points), the amplitude waveform with respect to the speed can be drawn clearly. At this time, the order can be analyzed up to about 25th order.
[0040]
{Circle around (2)} When the processing of one line measures 8 waveforms at fs = 64 points / waveform (512 points), fluctuation noise occurs in the amplitude waveform with respect to the speed. At this time, the order can be analyzed up to about 25th order. In this case, it is also possible to cope with a moving average (polynomial fitting method).
[0041]
As described above, in the high-speed uniformity measurement method of the present embodiment, it is not necessary to maintain the tire rotation speed constant, so the high-speed uniformity, or the high-speed uniformity and the residual unbalance are efficiently measured in a short time. be able to.
[0042]
In addition, since the measurement is performed with the rotational speed changed, the higher-order component can be evaluated by a peak value. In addition, the eigenvalue of the tire during tire rolling can also be estimated from this peak value. In addition, any speed and any order can be measured, and regenerative braking can be used while the speed is decreasing. The measurement method of this embodiment is a tire sorting machine as a high-speed uniformity measuring machine on the factory line. Can also be used.
[0043]
【The invention's effect】
As described above, according to the first aspect of the present invention, the high-speed uniformity of the tire is measured in a state where the rotational speed of the tire is changing in the first direction, and the state is changing in the second direction. The residual imbalance can be measured and measured while the tire rotates from the stopped state and returns to the stopped state, so there is no need to keep the tire rotating speed constant, and the primary component of the tire's high-speed uniformity is reduced. The effect that it can measure in time is acquired.
[Brief description of the drawings]
FIG. 1 is a schematic view of a measuring apparatus for measuring high-speed uniformity of a tire.
2 is a block diagram of a portion connected to the personal computer of FIG. 1. FIG.
FIG. 3 is a flowchart showing a measurement control routine by the personal computer of FIG. 1;
FIG. 4 is a diagram showing a correlation between measured values at a constant speed of high-speed RFV and TFV and measured values of the present embodiment.
FIG. 5 is a diagram showing a correlation between a measured value at a constant speed of RFV and a measured value of the present embodiment in each order.
FIG. 6 is a diagram showing the correlation between the measured value of the TFV at a constant speed and the measured value of the present embodiment in each order.
[Explanation of symbols]
18 drums 26 tires

Claims (1)

The high-speed uniformity is measured in a state where a load is applied to the tire and the rotation speed of the tire is changed in the first direction, the load is not applied to the tire, and the rotation speed of the tire is the first direction. The residual unbalance is measured in a state where the tire is changing in a second direction different from the above, or in a state where a load immediately before contact with the tire is applied and the rotational speed of the tire is changing in the second direction. A tire high-speed uniformity measurement method for measuring a primary component of high-speed uniformity by subtracting a measurement value of residual unbalance from a measurement value of the high-speed uniformity.

Images