JP2007121042A - Machine and method for testing tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly accurately measure tire characteristics. <P>SOLUTION: A tire testing machine is provided with both a spindle shaft rotated integrally with a tire and a bearing for rotation-freely supporting the spindle shaft to a housing, rotates a tire mounted to a rim, and measures tire characteristics by a measuring device. The tire testing machine is provided with a shaking device for forcefully generating vibrations in the spindle shaft. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a test apparatus (tire tester) for testing a tire, such as a uniformity test apparatus and a rolling resistance test apparatus, and a tire test method.

Conventionally, a uniformity testing apparatus as shown in Patent Document 1 is known as this type of tire testing machine. This uniformity test apparatus includes a spindle shaft, a housing, and a drum. A tire is mounted on a rim provided on the spindle shaft, and the tire is pressed against the drum to rotate the tire, thereby rotating the tire. Characteristics such as a tractive load and a radial load generated in the tire can be measured.
JP 2004-28700 A

Conventionally, in a uniformity testing device, the spindle shaft that is the tire rotation axis resonates during tire testing, or when the natural frequency of the spindle shaft system enters the vicinity of the frequency measured by the testing device (measuring device). Often, the natural frequency of the spindle shaft system can be a problem because the tire characteristics cannot be accurately measured.
In general, the natural frequency of the spindle shaft system is increased by increasing the support rigidity for supporting the spindle shaft, so that the influence of the vibration characteristics of the spindle shaft and its supporting system does not appear in the measurement results. However, due to structural constraints, it may be difficult to increase the natural frequency of the spindle shaft to the intended frequency.

In this case, the natural frequency of the spindle shaft may fall within the frequency measured by the test device (measurement device), and the actual tire characteristics may not be the same as the measurement value measured by the measurement device. .
In view of the above problems, an object of the present invention is to provide a tire testing machine capable of measuring a highly accurate tire characteristic.

In order to achieve the above object, the present invention has taken the following measures. That is, a tire that includes a spindle shaft that rotates integrally with the rim and a bearing that rotatably supports the spindle shaft with respect to the housing, and measures the characteristics of the tire with a measuring device by rotating the tire mounted on the rim. The test machine is provided with an excitation device that forcibly generates vibration on the spindle shaft.
According to this, the spindle shaft can be forcibly excited at a predetermined frequency.
Therefore, by measuring the tire characteristics (for example, radial load of the tire) while vibrating the spindle shaft, the relationship between the load characteristics applied to the spindle shaft and the tire characteristics measured by the measuring device (tester) Can be obtained.

  Therefore, when measuring the characteristics of a tire (when testing a tire), even if the rotation frequency of the spindle shaft or its higher order component approaches, for example, its natural frequency and the spindle shaft becomes in a resonance state. As described above, since the load transfer characteristic with respect to the frequency of the vibration of the spindle shaft can be obtained in advance as a transfer function before the tire test, the measured tire characteristic is corrected using the transfer function. Thus, even if the spindle axis is close to resonance, the tire characteristics can be accurately obtained. This makes it possible to measure the characteristics of the tire with high accuracy.

It is preferable that the excitation device includes an excitation control unit that varies a magnetic force generated by a stator arranged around the outer peripheral surface of the spindle shaft.
In this way, the spindle shaft can be vibrated in a non-contact state.
The vibration exciter includes an inertial mass disposed on the same axis as the spindle shaft, a connecting body that connects the inertial mass and the spindle shaft in a radial direction, an axis of the inertial mass, and an axis of the spindle shaft. It is preferable to have a moving body that moves the inertial mass in the radial direction such that the inertial mass is eccentric in the radial direction.

In this way, the spindle axis can be vibrated by moving the inertia mass to eccentrically decenter the axis of the inertia mass and the spindle axis in the radial direction and further rotating the spindle axis.
The bearing is preferably a non-contact bearing that supports the spindle shaft in a non-contact manner. By doing so, the rotational resistance of the bearing when the spindle shaft is rotated can be made very small, and the torsion torque of the spindle shaft caused by the rotational resistance can be made as small as possible.

Therefore, for example, when measuring a tractive load that is one of the characteristics of a tire, a torsional torque is hardly added to the tractive load, so that a highly accurate tractive load can be measured.
It is preferable that the non-contact bearing is composed of an active magnetic bearing, and the magnetic bearing is shared as a vibration exciter.
According to this, the bearing for supporting the spindle shaft and the vibration device can be shared (shared), and the configuration becomes very simple.

There is a transfer function calculating means for calculating, as a transfer function, a relationship between a load characteristic applied to the spindle shaft by the vibration exciter and a tire characteristic measured while the vibration is applied by the vibration exciter.
According to this, since the measured tire characteristic can be theoretically corrected using the transfer function during the tire test, the highly accurate tire characteristic can be measured.
Another means of the present invention is a tire testing machine equipped with a spindle shaft so that the tire can be rotated integrally with the spindle shaft, and the test of the tire is performed when measuring the characteristics of the tire with a measuring device. Before calculating the relationship between the tire characteristics measured while oscillating the spindle shaft and the excitation force as a transfer function in advance, and when testing the tire, the measured tire characteristics The correction is performed using the transfer function.

  According to this, even if the natural frequency of the spindle shaft is within the frequency measured by the measuring device and the spindle shaft may be in a resonance state, the transfer function obtained in advance before the tire test Since the measurement load measured using can be corrected, the characteristics of the tire can be measured with high accuracy.

  According to the present invention, highly accurate tire characteristics can be measured.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
What is shown in FIG. 1 is an overall front view of the tire testing machine, and what is shown in FIG. 2 is a schematic view of the supporting part side of another tire testing machine.
In FIG. 1, the vertical direction of the paper surface is the vertical direction, and in FIG. 2 the vertical direction of the paper surface is the vertical direction.
As shown in FIGS. 1 and 2, each of the tire testing machines 1A and 1B is, for example, a device for measuring tire uniformity, and includes a spindle shaft 3 rotatably supported and a rotatable drum 4. Have.

Hereinafter, the same structure is used for the tire testing machine 1A shown in FIG. 1 and the tire testing machine 1B shown in FIG.
The spindle shaft 3 of the tire testing machine 1A shown in FIG. 1 is provided with two upper and lower rotating shafts, an upper rotating shaft (upper spindle shaft 3a) and a lower rotating shaft (lower spindle shaft 3b). ) Are arranged in a main frame 5 having a frame shape. The upper spindle shaft 3a is disposed on the upper side of the main frame 5, and a lifting rod 8 of a center lifting cylinder 7 fixed to the main frame 5 is connected to the upper spindle shaft 3a. An upper rim 9 to which a tire T can be attached is provided at the lower part of the upper spindle shaft 3a.

The lower spindle shaft 3b is rotatably supported by a mounting base 10 disposed below the main frame 5. A lower rim 11 to which a tire T can be attached is provided on the upper part of the lower spindle shaft 3b.
According to the tire testing machine 1A in FIG. 1, the tire T to be tested is placed on the tire platform 12 supported so as to be movable up and down on the main frame 5, and the tire platform 12 is lowered to the lower spindle shaft 3b side to lower the lower spindle. While mounting the tire T on the lower rim 11 of the shaft 3b, the upper spindle shaft 3a is lowered by the center elevating cylinder 7, and the tire T is gripped by the upper and lower rims 9, 11.
The characteristics of the tire T are measured by separating the upper spindle shaft 3a and the upper rim 9 from the lifting rod 8 side and rotating the drum 4 by pressing the tire T and the drum 4 disposed in the main frame 5. Can do.

The spindle shaft 3 of the tire testing machine 1B shown in FIG. 2 is provided with one rotating shaft. The spindle shaft 3 is rotatably supported by a mounting base 10 having the same configuration as the tire testing machine 1A. A rim 13 fitted with a tire T can be attached to the upper part of the spindle shaft 3.
According to the tire testing machine 1B in FIG. 2, the tire T is attached to the rim 13, and the rim 13 is attached to the tip end of the spindle shaft 3 so that the spindle shaft 3 and the rim 13 rotate integrally. The characteristics of the tire T can be measured by pressing the tire T and the drum 4 arranged on the side of the mounting base 10 to rotate the drum 4.

Hereinafter, the structure for supporting the spindle shaft 3 of the tire testing machine 1A and the tire testing machine 1B, that is, the structure of the rotating shaft that rotatably supports the rim will be described in detail with reference to FIG.
Since the support structure of the spindle shaft 3 (lower spindle shaft 3b) in the tire testing machine 1A is the same support structure as the spindle shaft 3 in the tire testing machine 1B of FIG. 2, the tire testing machine 1A is shown in FIG. The tire testing machine 1B will be described as an example. The tire testing machine 1B in FIG. 2 is different from the tire testing machine 1A in FIG. 1 in that a tire with a rim in which a tire T is held in advance on a rim 13 is supported on a spindle shaft 3.

As shown in FIG. 2, a housing 15 is fixed to the upper part of the mounting base 10. The housing 15 includes a cylindrical spindle base 16 disposed on the upper surface of the mounting base 10, and a cylindrical bearing housing 17 fitted inside the spindle base 16.
A flange 18 that protrudes radially outward is formed on the upper side of the bearing housing 17, and a measuring device 20 that measures the characteristics of the tire T is provided between the flange 18 and the upper portion of the spindle base 16. Is provided. The measuring device 20 includes a plurality of load cells and the like, and can measure a load, a moment, and the like applied to the tire T when the tire T is pressed against the drum 4 and the tire T is rotated.

A spindle shaft 3 (the lower spindle shaft 3b in the case of FIG. 1) is fitted in the bearing housing 17. The spindle shaft 3 is rotatably supported with respect to the bearing housing 17 (housing 15) by a non-contact bearing 23 capable of supporting the spindle shaft 3 in a non-contact manner. The non-contact bearing 23 is composed of, for example, a magnetic bearing that supports the spindle shaft 3 in a non-contact manner by electromagnetic force (details are described in the third embodiment).
The magnetic bearing 23 includes a radial bearing 24 that receives a radial load of the spindle shaft 3 and a thrust bearing 25 that receives a thrust load of the spindle shaft 3. In the embodiment, the magnetic bearing 23 is provided with two radial bearings 24 a and 24 b and one thrust bearing 25 that are arranged one above the other.

Specifically, an upper radial bearing 24a is provided on the upper side of the bearing housing 17, and a lower radial bearing 24b is provided in the middle of the upper and lower sides of the bearing housing 17, and a thrust bearing 25 is provided below the lower radial bearing 24b. The spindle shaft 3 is rotated with respect to the bearing housing 17 by these bearings 24 and 25.
Excitation for forcibly oscillating the spindle shaft 3 by changing the position of the spindle shaft 3 with respect to the magnetic bearing 23 on the upper side of the spindle shaft 3, that is, on the end portion side of the spindle shaft 3 on which the rim is mounted. A device 50 is provided.

The vibration testing device 50 of the tire testing machine 1A and the tire testing machine 1B will be described in detail with reference to FIGS. The vibration device of the tire testing machine 1A has the same configuration as that of the vibration testing device 50 of the tire testing machine 1B, so that the same reference numerals are given and description thereof is omitted.
The vibration device 50 includes an electromagnet 51 disposed around the outer peripheral surface of the spindle shaft 3 and a vibration control unit 52. The electromagnet 51 is provided on a support 53 attached to the spindle base 16. For example, the support 53 is formed in a cylindrical shape, and the lower side thereof is fitted and fixed to the spindle base 16. The electromagnet 51 is attached to the vicinity of the edge of the insertion hole 56 through which the spindle shaft 3 is inserted. Yes.

Specifically, an electromagnet 51 is attached to the upper wall 54 of the support 53 in which the insertion hole 56 is formed, and the electromagnet 51 is fixed to the support 53 in a state of being close to the outer peripheral surface of the spindle shaft 3. . More specifically, the two electromagnets 51L and 51R are fixed to the support 51 in a plan view with the center of the insertion hole 56, in other words, the axis of the bearing housing 17 as a center, thereby constituting a stator. ing.
The electromagnets 51L and 51R are formed by winding a coil around an iron core, and a sleeve 55 made of metal or a magnetic material is attached to the outer peripheral surface of the spindle shaft 3 so as to face the electromagnets 51L and 51R, thereby constituting a rotor. Yes.

Although FIG. 3 shows a pair of electromagnets 51L and 51R that vibrate in one direction, by arranging a pair of electromagnets in a perpendicular relationship with the electromagnets 51L and 51R in the horizontal direction (the through direction in FIG. 3). The vibration may be applied in any direction within the horizontal direction.
The vibration control unit 52 supplies a current to the coils of the electromagnets 51 and thereby vibrates the spindle shaft 3. Specifically, the vibration control unit 52 arbitrarily changes the amplitude and frequency of the current supplied to the coil of each electromagnet 51, thereby “magnetic attraction force acting between the electromagnet 51L and the sleeve 55”. And the balance state of “the magnetic attraction force acting between the electromagnet 51R and the sleeve 55” is changed, and thereby the spindle shaft 3 is vibrated with respect to the electromagnets 51L and 51R.

More specifically, the vibration control unit 52 has a signal generation function (signal generation means) that arbitrarily supplies current at a predetermined frequency, and changes the amplitude and frequency of the current supplied to the electromagnets 51L and 51R. be able to. For example, when a sine wave signal is output by the vibration control unit 52, the upper side of the spindle shaft 3 is vibrated in the radial direction. The spindle shaft 3 vibrates according to the frequency of the sine wave signal output from the vibration control unit 52.
3 shows a state where the center O1 of the arrangement of the electromagnets 51L and 51R and the axis O2 of the spindle shaft 3 coincide with each other, and FIG. 4 shows the center O1 of the arrangement of the electromagnets 51L and 51R and the spindle. A state where the shaft center O2 of the shaft 3 vibrates due to vibration is shown.

In the tire tests 1A and 1B having the vibration generator 50, the tire test is performed as follows. Hereinafter, a tire test method using the vibration generator 50 will be described.
Before the tire test, the vibration device 50 is used to measure the force generated on the tire T when the spindle shaft 3 is vibrating (radial load of the tire T, etc.) and the state where the spindle shaft 3 is vibrating. The relationship with the value measured by the apparatus 20 is obtained.
Here, the force generated in the tire T is a load generated by the vibration device 45. Alternatively, the force generated in the tire is obtained from the geometric relationship between the vibration device 45 and the tire position.

Specifically, first, as a preliminary test before the test of the tire T, the tire T is mounted on the rim, and the tire T and the drum 4 are pressed against each other. At this time, the tire T may or may not be rotated.
Next, an output signal S1 having a predetermined frequency is generated by the signal transmitter 42, and the spindle shaft 3 is vibrated at a predetermined frequency. Then, the radial load of the tire T with the spindle shaft 3 vibrating in the radial direction is measured by the measuring device 20. A measured value measured by the measuring device 20 in a state where the spindle shaft 3 is vibrating is taken as a response value. Further, the excitation force applied to the spindle shaft 3 is used as a reference value.

Then, the frequency of the output signal S1 output from the signal transmitter 42 is changed, and the vibration frequency when the spindle shaft 3 is vibrated by the vibration device 50 is continuously within a range including the natural frequency of the spindle shaft 3, for example. The response value at that time is recorded while being variable, and the vibration frequency and the radial load of the tire T at each vibration frequency are stored in a computer or the like.
Using the vibration frequency stored in the computer, the load (reference value) applied to the spindle shaft 3 and the measured value (response value) of the radial load for each vibration frequency, a radial load transfer function is obtained.

Specifically, as shown in FIG. 5, the horizontal axis represents the vibration frequency when the spindle shaft 3 is vibrated, and the value obtained by dividing the radial load (response value) for each vibration frequency by the reference value (the amplitude of the transfer function). ) Is plotted on the vertical axis, and each data when measured by the measuring device 20 is plotted to create a frequency response curve (transfer function).
At the same time, using the same data, as shown in FIG. 6, a curve of the time delay of the radial load measured by the measuring device 20 in the frequency response may be created. In this case, the vertical axis in the figure is a value indicating the time delay (phase of the transfer function).

When testing the tire T, the driving of the vibration device 50 is stopped, and the radial load of the tire T when the tire T is rotated is measured by the measuring device 20.
Specifically, the tire T is mounted on the rim, the tire T and the drum 4 are pressed against each other, and the tire T is rotated at a predetermined rotation speed (for example, 40 rpm to 70 rpm).
And the radial load of the tire T is measured with the measuring apparatus 20, and the measured value measured with the measuring apparatus 20 is corrected using a transfer function as shown in FIG. That is, the rotational frequency of the spindle shaft 3 obtained from the rotational speed of the tire T at the time of measurement is applied to the vibration frequency in FIG. 5, and the reciprocal of the value on the vertical axis (the amplitude of the transfer function) is used for measurement. The measurement value measured by the apparatus 20 is corrected.

For example, if the amplitude of the transfer function corresponding to the vibration frequency calculated from the rotation speed of the tire T is 2.0, the measurement is performed by measuring “1 / 2.0”, which is the inverse of the value, with the measuring device 20. A value obtained by multiplying the value is a true radial load of the tire T. Note that FIG. 6 may be used to see the time delay of the measured value measured by the measuring device 20 when the spindle shaft 3 vibrates.
Due to this correction, even when the spindle shaft 3b in the tire testing machine 1A and the spindle 3 in the tire testing machine 1B are rotating in a state close to its natural frequency (fb in FIG. 5), the phase shift is accurate and accurate. Thus, it is possible to obtain a radial load without any failure, and thus, it is possible to measure the characteristics of the tire T with high reliability and reliability.

Transfer function calculating means (the computer) for calculating a relationship between the frequency of the vibration of the spindle shaft 3 generated by the vibration generator 50 and the characteristics of the tire measured while vibrating with the vibration apparatus 50 as a transfer function. You may make it provide in tire testing machine 1A, 1B.
[Second Embodiment]
7 and 8 show a part of the tire testing machine in the second embodiment. In this embodiment, the vibration exciter in the first embodiment is modified.
The vibration device 60 includes an inertia mass 61, a connecting body 62, and a moving body 63. The inertial mass 61 is provided on the upper side of the spindle shaft 3 and inside thereof. Specifically, a space 64 is formed inside the spindle shaft 3, and an inertia mass 61 configured by, for example, a cylindrical metal lump or steel bar cut into a predetermined length in the space 64. Are arranged apart from the inner wall of the spindle shaft 3.

In a normal state (non-vibration state), the axis O4 of the inertial mass 61 and the axis O2 of the spindle shaft 3 are on the same axis, in other words, the inertial mass 61 is in relation to the spindle shaft 3. In the non-eccentric state, the inertia mass 61 is connected to the spindle shaft 3 in the radial direction via the connecting body 62. The connecting body 62 is composed of an elastic body such as a spring. During non-vibration, it is firmly fixed in a concentric state.
The moving body 63 is disposed on the side of the inertia mass 61 and is supported by the spindle shaft 3 so that a part or the whole of the moving body 63 can move in the radial direction with respect to the spindle shaft 3. The moving body 63 is constituted by, for example, a piezo element in which the protruding portion 63a moves in the radial direction by an electric signal.

Therefore, by supplying a voltage to the piezo element 63, the protrusion 63a of the piezo element 63 moves in the radial direction, and the inertia mass 61 can be moved in the radial direction by the protrusion 63a.
As described above, according to this vibration exciter, the inertia mass 61 is moved in the radial direction by the protruding portion 63a of the piezo element 63, and the axis O4 of the inertia mass 61 and the axis O2 of the spindle shaft 3 are eccentric in the radial direction. By rotating the spindle shaft 3 in this state, the spindle shaft 3 can be vibrated in the radial direction (radial direction).
[Third Embodiment]
The thing shown to FIGS. 9-11 has shown the tire testing machine in 3rd Embodiment. In this tire testing machine, the magnetic bearing 23 in the first embodiment, that is, the radial bearing 24 is used as the vibration device 50. In this embodiment, the support body 53 is not provided.

As shown in FIGS. 9 to 10, each radial bearing 24 includes a plurality of electromagnets 28, a metal or magnetic sleeve 29, a power supply unit 30, a displacement sensor 31, and a control unit 32. ing.
Each electromagnet 28 is attached around the inner wall of the bearing housing 17 and is arranged around the outer peripheral surface of the spindle shaft 3 to constitute a stator. Specifically, a pair of electromagnets 28L, 28R are arranged in a state of being divided into left and right in plan view with the axis of the bearing housing 17 as the center, and a pair orthogonal to the pair of electromagnets 28L, 28R. The electromagnet (not shown) is arranged. The sleeve 29 is attached to the outer peripheral surface of the spindle shaft 3 so as to face each electromagnet, and the sleeve 29 constitutes a rotor.

9 and 10, only the electromagnets 28L and 28R in one direction (radial direction) are shown, but the pair of the above-described pairs that are orthogonal to the pair of electromagnets 28L and 28R in the horizontal direction (the through direction in FIG. 10). By arranging this electromagnet, it is configured to function as a radial bearing.
The power supply unit 30 supplies current to the electromagnets 28L and 28R, that is, the coil 33 wound around the iron core. The power supply unit 30 includes, for example, a power amplifier that amplifies the current output from the control unit 32.

Therefore, a current is supplied from the power supply unit 30 to the coil 33 and an electromagnetic attractive force is applied between the electromagnets 28L and 28R and the sleeve 29, thereby supporting the radial load of the spindle shaft 3 in a non-contact state. is doing.
The displacement sensor 31 detects the position of the spindle shaft 3 in the radial direction (radial direction). For example, the radial center of the spindle shaft 3 with respect to the center O5 (stator center O5) of the arrangement of the electromagnets 28L and 28R. The displacement in the direction, in other words, the radial displacement of the axis O2 of the spindle shaft 3 relative to the axis of the bearing housing 17 can be detected. Specifically, the displacement sensor 31 measures the distance between the sleeve 29 and the displacement sensor 31, and obtains the distance to the axis O2 by adding the radius of the spindle shaft 3 to the measurement result. Can do.

The control unit 32 adjusts the current (control signal S2) output to the power supply unit 30 based on information on the target position of the axis O2 of the spindle shaft 3 and the position of the spindle shaft 3 detected by the displacement sensor 31. The current supplied from the power supply unit 30 to the coils 33 of the electromagnets 28L and 28R is controlled.
That is, as shown in FIG. 11, the control unit 32 is preset with a target value corresponding to the target position of the axis O2 of the spindle shaft 3, and the position of the axis O2 of the spindle shaft 3 is determined by the displacement sensor 31. Thus, the current value corresponding to the position of the axis O2 is set. Then, the control unit 32 compares the target value with the current value, and adjusts the current output from the power supply unit 30 so that the position of the axis O2 of the spindle shaft 3 becomes the target position.

  In this embodiment, the target position of the axis O2 of the spindle shaft 3 is the center O5 position of the arrangement of the electromagnets 28L and 28R, and the displacement sensor 31 is the axis of the spindle shaft 3 with respect to the center O5 of the arrangement of the electromagnets 28L and 28R. When the displacement sensor 31 detects the radial displacement of the axis of the spindle shaft 3 with respect to the center O5 of the arrangement of the electromagnets 28L and 28R, the control unit 32 detects the displacement of the electromagnets 28L and 28R. The current output from the power supply unit 30 is set so that the radial displacement with respect to the arrangement center O5 becomes zero (so that the arrangement center O5 of the electromagnets 28L and 28R coincides with the axis O2 of the spindle shaft 3). change.

For example, when the displacement sensor 31 measures a distance greater than the set value, the spindle shaft 3 is rotating eccentrically toward the electromagnet 28L, so the power supply unit 30 increases the current to the electromagnet 28R, By increasing the magnetic force generated by the electromagnet 28R and pulling the spindle shaft 3 toward the electromagnet 28R, the eccentric state is corrected.
Here, the radial direction has been described as an example, but the same applies to a direction orthogonal thereto.
Next, description will be made by taking, as an example, the use of the upper radial bearing 24a disposed near the rim among the radial bearings 24 as a vibration device.

In addition to the electromagnets 28L and 28R, the sleeve 29, the power supply unit 30, the displacement sensor 31, and the control unit 32, the upper radial bearing 24a used as the vibration device 50 includes a signal generator that generates an arbitrary waveform voltage or current. 42. In this embodiment, a function generator is employed as the signal generator 42.
The signal generator 42 is connected to at least one of the power supply units 30 corresponding to the electromagnets 28L and 28R, and when the signal generator 42 outputs the output signal S1, the control signal S2 output from the control unit 32 is output. The output signal S1 is added, and the added control signal S3 is input to one power supply unit 30a.

By adding the output signal S1 of the signal generator 42 to the control signal S2 output from the control unit 32, the current output from the power supply unit 30a to the electromagnets 28L and 28R changes and is provided above the spindle shaft 3. The magnetic attractive force between the sleeve 29 and the electromagnets 28L and 28R changes.
When a sine wave signal is output from the signal generator 42 at a predetermined frequency, the upper side of the spindle shaft 3 is vibrated in the radial direction in accordance with the frequency of the output signal S1 output from the signal generator 42.

A method of obtaining a true radial load by using the vibration device (radial bearing 24a) described above, that is, a force generated in the tire T when the spindle shaft 3 is vibrating (a radial load of the tire T, etc.) Then, the relationship with the value measured by the measuring device 20 in a state where the spindle shaft 3 is oscillating is obtained, and the transfer function of the radial load is obtained from the result and measured by the measuring device 20 using the obtained transfer function. The method of correcting the measured value and obtaining the true radial load is substantially the same as that of the first embodiment, and thus the description thereof is omitted here.
The present invention is not limited to the above embodiment.

That is, in the above embodiment, the radial load is measured by the measuring device 20, but what is measured is not limited to this, and a lateral load, a tractive load, a moment, or the like may be measured.
In this case, a lateral load and a steering torque when the spindle shaft 3 vibrates at a predetermined frequency is measured in advance, a transfer function for the measured load and torque is obtained, and the obtained transfer function is used to perform a tire characteristic test. It is advisable to correct the measurement result.
The bearing 23 that supports the spindle shaft 3 may be constituted by a non-contact type fluid bearing or a mechanical rolling bearing.

In the tire testing machine illustrated in the above embodiment, the spindle shaft 3 is arranged in the vertical direction, but the present invention may be one in which the spindle shaft 3 is arranged in a horizontal direction or an oblique direction.
In the tire testing machine illustrated in the above embodiment, the spindle shaft support structure is provided below the tire T. In the present invention, the spindle shaft support structure is provided above the tire T. May be.

1 is an overall front view of a tire testing machine according to a first embodiment of the present invention. It is the schematic of another tire testing machine. It is detail sectional drawing of a vibration apparatus. It is a control block diagram of a vibration exciting device. It is a figure which shows a transfer function (vibration frequency-amplitude). It is a figure which shows a transfer function (vibration frequency-phase difference) It is sectional drawing of the vibration apparatus provided in the tire testing machine in 2nd Embodiment. It is a top view of a vibration apparatus. It is the schematic of the lower part of the tire testing machine in 3rd Embodiment. It is sectional drawing of a vibration apparatus. It is a control block diagram of a vibration exciting device.

Explanation of symbols

1A Tire Testing Machine 1B Tire Testing Machine 3 Spindle Shaft 23 Bearing 50 Excitation Device T Tire

Claims (7)

A tire testing machine comprising a spindle shaft that rotates integrally with a rim, and a bearing that rotatably supports the spindle shaft with respect to a housing, and that measures tire characteristics with a measuring device by rotating a tire mounted on the rim. In
A tire testing machine provided with a vibration generator that forcibly generates vibration on the spindle shaft.   2. The tire testing machine according to claim 1, wherein the vibration device includes a vibration control unit that varies a magnetic force generated by a stator disposed around an outer peripheral surface of the spindle shaft. .   The vibration exciter includes an inertial mass disposed on the same axis as the spindle shaft, a connecting body that connects the inertial mass and the spindle shaft in a radial direction, an axis of the inertial mass, and an axis of the spindle shaft. The tire testing machine according to claim 1, further comprising a moving body that moves the inertial mass in the radial direction such that the inertial mass is eccentric in the radial direction.   The tire testing machine according to any one of claims 1 to 3, wherein the bearing is a non-contact bearing that supports the spindle shaft in a non-contact manner.   5. The tire testing machine according to claim 4, wherein the non-contact bearing is constituted by an active magnetic bearing, and the magnetic bearing is shared as a vibration exciter.   It has a transfer function calculating means for calculating, as a transfer function, a relationship between a load characteristic applied to the spindle shaft by the vibration exciter and a tire characteristic measured while being vibrated by the vibration exciter. The tire testing machine according to any one of claims 1 to 5. In a tire testing machine equipped with a spindle shaft that can rotate freely, the tire is rotated integrally with the spindle shaft and a test is performed to measure the characteristics of the tire with a measuring device.
Prior to the test of the tire, the relationship between the tire characteristics measured while vibrating the spindle shaft and the force of vibration is calculated in advance as a transfer function,
A tire test method comprising correcting the measured tire characteristics using the transfer function when testing the tire.

Images