JP2008039510A - Vibration measuring method and vibration measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a vibration characteristic of a structure to be evaluated simply and to improve precision of evaluating the vibration characteristic of the structure. <P>SOLUTION: A vibration measuring apparatus 1 is provided with: a structure support 4 for supporting a tire 11; a hammer 6 for vibrating the structure support 4; a first vibrometer 21 for detecting vibrations of the tire 11; and a second vibrometer 22 for detecting vibrations of the structure support 4. When evaluating the vibration characteristic of the tire 11, the structure support 4 is vibrated by using the hammer 6, and a vibration analyzing device 23 calculates the vibration transmissivity T equal to -X1/X2 of the tire 11 from the ratio of the vibration X1 of the tire acquired by the first vibrometer 21 to the vibration X2 of the structure support 4 acquired by the second vibrometer 22. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for measuring vibration of a structure.

  In designing a structure, it is important to evaluate vibration characteristics. For example, one way to evaluate the vibration characteristics of a tire is to attach it to a wheel and attach a tire loaded with internal pressure to a structure support. There is a method of measuring and evaluating vibration characteristics. However, the resonance of the structure support often appears in the frequency range to be evaluated (in the case of a tire, it is evaluated up to a frequency of 400 Hz or more, whereas the resonance of a normal tire testing machine is 200 Hz to 300 Hz), There was a problem that the evaluation accuracy of the vibration characteristics was lowered. For example, Patent Document 1 discloses a technique for reducing the influence of the resonance frequency of the system of the structure support and the spring by improving the rigidity of the structure support and floating the structure support with a spring. It is disclosed.

Japanese Patent Laid-Open No. 11-142295

  However, in the technique of Patent Document 1, in order to secure the rigidity of the structure support, the vibration measurement device becomes large and the structure of the structure support becomes complicated, so that it is difficult to perform simple measurement. was there. Therefore, the present invention has been made in view of the above, and a vibration measuring method and a vibration measuring apparatus capable of easily evaluating the vibration characteristics of a structure and improving the evaluation accuracy of the vibration characteristics of the structure. The purpose is to provide.

  In order to solve the above-described problems and achieve the object, the vibration measurement method according to the present invention includes a procedure for exciting a structure support that supports a structure to be evaluated for vibration characteristics, and the structure support. A procedure for acquiring vibration of the structure support and vibration of the structure in a plane including a body axis and a direction in which the structure support is vibrated, the acquired vibration of the structure, and the structure And a procedure for calculating a vibration transmissibility of the structure based on a ratio to the vibration of the object support.

  In this vibration measuring method, a structure to be evaluated for vibration characteristics is attached to a structure support, and the structure support is vibrated to obtain vibrations of the structure support in a vibration unit. The vibration of the structure is acquired, and the vibration transmissibility of the structure is calculated based on the ratio between the acquired vibration of the structure support and the vibration of the structure. Thereby, this vibration measuring method can easily evaluate the vibration characteristics of the structure and can improve the evaluation accuracy of the vibration characteristics of the structure.

  The vibration measuring method according to the present invention is characterized in that, in the vibration measuring method, the structure support is vibrated by a vibration device.

  In the vibration measuring method according to the present invention, in the vibration measuring method, when the structure support is vibrated, two different places of the structure support are vibrated, and at each vibration place. The direction of excitation is parallel.

  The vibration measurement method according to the present invention is the vibration measurement method, wherein vibration detection means are provided at two locations separated in the axial direction of the structure support, and the shaft of the structure support and the direction of excitation are provided. And detecting a vibration component of rotation in a plane including

  The vibration measurement method according to the present invention is the vibration measurement method, wherein the vibration of the structure and the vibration of the structure support when the difference between the vibrations at the two different locations falls within a predetermined threshold. And the vibration transmissibility is calculated.

  The vibration measurement method according to the present invention is the vibration measurement method, further comprising two vibration devices for vibrating the structure support, and at least one vibration force of the vibration device. By controlling, the vibration component of the rotation is suppressed.

  The vibration measurement method according to the present invention is the vibration measurement method, wherein the vibration of the structure and the vibration of the structure support are obtained by exciting with a sine wave, and at a predetermined frequency resolution. The vibration of the structure and the vibration of the structure support are acquired for each frequency resolution by changing the frequency of the sine wave.

  The vibration measurement method according to the present invention is characterized in that, in the vibration measurement method, the vibration level of the structure support is adjusted to a predetermined magnitude based on the acquired vibration of the structure support. .

  The vibration measuring method according to the present invention is characterized in that, in the vibration measuring method, the structure is a tire or a tire / wheel assembly.

  The vibration measurement method according to the present invention is the vibration measurement method, wherein the tire or the tire constituting the tire / wheel assembly is removed from the ground in a state where the tire or the tire / wheel assembly is attached to a vehicle. The vibration of the tire or the tire / wheel assembly is measured in a floating state.

  A vibration measuring apparatus according to the next invention detects a vibration of the structure, a structure support that supports the structure whose vibration characteristics are to be evaluated, a vibration means that vibrates the structure support, and the like. First vibration detection means, second vibration detection means for detecting vibration of the structure support, vibration of the structure support obtained from the second vibration detection means, and acquisition from the first vibration detection means And a vibration analysis device that calculates a vibration transmissibility of the structure based on a ratio with the vibration of the structure.

  In this vibration measuring apparatus, a structure to be evaluated for vibration characteristics is attached to a structure support, the structure support is vibrated by a vibration means, and the vibration of the structure support is vibrated by a second vibration detection means. And the vibration of the structure is acquired by the first vibration detecting means. Then, based on the acquired ratio of the vibration of the structure support to the vibration of the structure, the vibration transmissibility of the structure is calculated. Thereby, this vibration measuring method can easily evaluate the vibration characteristics of the structure and can improve the evaluation accuracy of the vibration characteristics of the structure.

  The vibration measuring apparatus according to the present invention includes a structure support that supports a structure whose vibration characteristics are to be evaluated, a first vibration device that vibrates the structure support, and the structure support. On the other hand, by inputting in a direction parallel to the first vibration device, a second vibration device that vibrates the structure support, first vibration detection means for detecting vibration of the structure, A second vibration detecting means for detecting a vibration of the structure support, a vibration of the structure support obtained from the second vibration detecting means, and a vibration of the structure obtained from the first vibration detecting means. And a vibration analyzer that calculates a vibration transmissibility of the structure based on the ratio.

  This vibration measuring apparatus is configured to input vibrations from two locations to a structure support that supports a structure to be evaluated for vibration characteristics by the first vibration device and the second vibration device. The vibration component of rotation generated in the structure to be evaluated is suppressed. Thereby, in this vibration measuring apparatus, the vibration characteristics of the structure can be easily evaluated, and furthermore, the vibration component of the rotation of the structure can be suppressed, and the evaluation accuracy of the vibration characteristics of the structure can be further improved.

  In the vibration measuring apparatus according to the next aspect of the present invention, in the vibration measuring apparatus, the second vibration detecting means is provided at two locations separated in the axial direction of the structure support body, and is based on the first vibrating device. First vibration device vibration detection means for detecting vibration of the structure support and second vibration device vibration detection means for detecting vibration of the structure support by the second vibration device In addition, the vibration of the structure support is detected by at least one of the vibration detection means for the first vibration device and the vibration detection means for the second vibration device.

  With the vibration measuring method and the vibration measuring apparatus according to the present invention, the vibration characteristics of the structure can be easily evaluated, and the evaluation accuracy of the vibration characteristics of the structure can be improved.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited by the best mode for carrying out the invention (hereinafter referred to as an embodiment). In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art, or substantially the same, so-called equivalent ranges. In the following description, a pneumatic tire is a structure to be evaluated for vibration characteristics. However, a structure that can be evaluated for vibration characteristics by applying the present invention is not limited to a tire. For example, the present invention is also applicable to measuring vibration characteristics and evaluating vibration characteristics of a wheel on which a tire is assembled or a structure (flywheel, propeller, antenna, etc. of an internal combustion engine) used in a state where one end is constrained. Can be applied.

(Embodiment 1)
In Embodiment 1, a structure to be evaluated for vibration characteristics is attached to a structure support, and the structure support is vibrated to obtain vibration of the structure support. get. And the characteristic is that the vibration transmissibility of the structure is calculated based on the acquired vibration of the structure support and the vibration of the structure. In the first embodiment, one place of the structure support is vibrated.

  FIG. 1 is a schematic explanatory diagram when the vibration measurement method according to the first embodiment is executed by the vibration measurement apparatus according to the first embodiment. In the first embodiment, the tire 11 constituting the tire / wheel assembly 10 is a structure to be evaluated for vibration characteristics. The tire 11 is a pneumatic tire.

  The vibration measuring apparatus 1 according to the first embodiment includes an apparatus base 2, a structure support 4, a first vibrometer 21 that is a first vibration detecting unit, and a second vibrometer 22 that is a second vibration detecting unit. The vibration analysis device 23 is included. The structure support body 4 is comprised with a rod-shaped member. Here, the first vibrometer 21 and the second vibrometer 22 may be any of a displacement meter, a speedometer, and an accelerometer. A bracket 5 to which a wheel 12 constituting the tire / wheel assembly 10 is attached is provided at one end of the structure support 4. The structure support 4 is fixed to the device base 2 via the structure support fixture 3 provided on the device base 2 on the other end side of the structure support 4 to which the bracket 5 is not attached. The

  In the vibration measuring method according to the first embodiment, the structure support 4 is vibrated instead of directly vibrating the tire 11 which is a structure whose vibration characteristics are to be evaluated. When the structure support 4 is vibrated by the vibration measuring apparatus 1, the structure support 4 is hit by a hammer 6 serving as a vibration means. A first vibrometer 21 is attached to the tread portion 11T of the tire 11, and a second vibrometer 22 is attached to the structure support 4. Then, the vibration of the tire 11 is detected by the first vibrometer 21, and the vibration of the structure support body 4 is detected by the second vibrometer 22.

  The vibration of the tire 11 detected by the first vibrometer 21 and the vibration of the structure support body 4 detected by the second vibrometer 22 are taken into the vibration analysis device 23. In this embodiment, the vibration analyzer 23 incorporates, for example, a 2-channel FFT (Fast Fourier Transform) analyzer. As for the vibration of the tire 11 and the vibration of the structure support body 4 taken into the vibration analysis device 23, a vibration transmissibility T (hereinafter referred to as transmissibility) T of the tire 11 which is a structure to be evaluated for vibration characteristics is calculated. The transmission rate T is frequency-analyzed by FFT.

  Here, the transmission rate T in this embodiment is represented by -X1 / X2. X1 is the vibration (displacement, speed, acceleration) of the tire 11 detected by the first vibrometer 21, and X2 is the vibration (displacement, speed, acceleration) of the structure support 4 detected by the second vibrometer 22. . That is, in this embodiment, the transmissibility T is represented by the ratio of the vibration X1 of the tire 11 obtained by exciting the structure support 4 and the vibration X2 of the structure support 4.

  FIG. 2A is an explanatory diagram of a conventional vibration measurement method. 2-2 is explanatory drawing which shows the vibration experiment which vibrates the structure support body of a tire using the installation which performs the conventional vibration measuring method. FIG. 3A is an explanatory diagram of an example of a transmission rate obtained by a conventional vibration measurement method. 3-2 is explanatory drawing which shows an example of the transmissibility obtained as a result of vibrating the structure support body of a tire / wheel assembly using the equipment which performs the conventional vibration measuring method.

  As shown in FIG. 2A, when evaluating the vibration characteristics of the tire 11 that is a structure to be evaluated for vibration characteristics by the conventional vibration measurement method, an input P is given to the tread portion 11T of the tire 11. The response (force) RE appearing on the structure support 4 of the tire 11 was acquired, and the transmission rate T (response / input) was obtained. In general, in the tire 11, vibrations in the primary cross section appear at 100 Hz or less, and vibrations in the secondary cross section appear around 300 Hz. This appears as a peak in transmission rate T.

  In the conventional vibration measuring method, as shown in FIG. 3-1, a plurality of peaks of the transmission factor T appear around 300 Hz (portion indicated by K in FIG. 3A), and any peak evaluates vibration characteristics. It is difficult to determine whether it is the natural frequency of the tire 11 that is the target structure. Here, in the example shown in FIG. 2B, an input P is given to the structure support 4 of the tire 11, a response (force) RE appearing on the structure support 4 is acquired, and a transmission rate T (response / input) is obtained. ) Then, as shown in FIG. 3-2, a peak of the transmission rate T appears in the vicinity of 250 Hz (a portion indicated by L in FIG. 3-2). The peak of the transmission rate T coincides with one of the peaks of the transmission rate T appearing around 300 Hz shown in FIG.

  From the results shown in FIGS. 3A and 3B, in the conventional vibration measurement method, it is considered that the accuracy of the transmission rate T of the tire 11 is lowered due to the resonance of the structure support 4. For this reason, it is difficult to determine which peak of the transmission factor is that of the tire 11 with only the transmission factor T. With the conventional vibration measurement method, the vibration characteristics of the tire 11 existing at 250 Hz to 400 Hz are obtained. It was not possible to evaluate accurately.

  The present inventors have found the above cause through intensive research, and have completed the vibration measurement method according to the first embodiment. In this vibration measuring method, the structure support 4 is vibrated in place of the tire 11 which is a structure to be evaluated for vibration characteristics, and the vibration X1 of the tire 11 which is a structure to be evaluated for vibration characteristics is The transmission rate T is expressed as a ratio to the vibration X2 of the structure support 4. By using the transmissibility T obtained in this way, the influence of resonance of the structure support 4 is eliminated, and the vibration characteristics of the tire 11 that is the structure whose vibration characteristics are to be evaluated are accurately evaluated. be able to. Since the transmission rate T is −X1 / X2, the accuracy of the transmission rate T is lowered unless the structure support 4 is vibrated appropriately. For this reason, the structure support body 4 and its fixing structure are comprised so that the vibration of the structure support body 4 can be accept | permitted moderately. Next, the concept of this vibration measuring method will be described.

  FIG. 4 is a conceptual diagram illustrating the concept of the vibration measurement method according to the first embodiment. In the vibration measurement method according to the first embodiment, a measurement method equivalent to the conventional vibration measurement method is obtained from the relational expression of the transfer function. FIG. 4A (left side) shows that the tire 11, which is the structure whose vibration characteristics are to be evaluated, is fixed to the structure support body 4 and the structure support body 4 is fixed and the tire 11 is vibrated. The vibration of the tire 11 at the time is shown. A ′ (first term on the right side) of FIG. 4 shows a case where the structure support 4 is vibrated and the tire 11 and the structure support 4 vibrate. Moreover, B of FIG. 4 shows restraining the structure support body 4. FIG. The state of A in FIG. 4 is equivalent to the restraint of the structure support 4 in the state of A ′ in FIG. The relationship between the input and output of A ′ can be expressed by Equation (1). Here, the subscript 1 indicates the tire 11, and the subscript 2 indicates the structure support 4. f represents force and X represents displacement. H is a transfer function.

When the tire 11 and the structure support 4 vibrate (A ′ in FIG. 4), the state of restraining the structure support 4 can be expressed by setting X2 = 0 in Equation (1). Since X2 = 0, H ₁₂ × f ₁ + H ₂₂ × f ₂ = 0 from Equation (1). When the tire 11 and the structure support 4 vibrate, the transmission rate T when the structure support 4 is constrained is T = f ₂ / f ₁ = −H ₁₂ / H ₂₂ . Here, since H ₁₂ = X1 / f ₂ and H ₂₂ = X2 / f ₂ , the transmission rate T = −X1 / X2 (however, input to the structure support 4).

  From this, the ratio X1 / X2 between the vibration X1 of the tire 11 obtained by exciting the structure support 4 and the vibration X2 of the structure support 4 is a transmission rate when the structure support 4 is fixed. Equivalent to T. By using the transmission rate T (= X1 / X2) obtained in this way, the influence of the resonance of the structure support 4 is eliminated, and the vibration of the tire 11 which is the structure whose vibration characteristics are to be evaluated. The characteristics can be evaluated accurately and easily. Further, since the vibration characteristics can be evaluated while being fixed to the rotating shaft of the tire 11, the influence of the mass of the wheel 12 can be removed, and the vibration characteristics of the tire 11 alone can be accurately evaluated.

  When evaluating the vibration characteristics of the tire 11, for example, the natural frequency of the tire 11 is extracted from the transmission rate T obtained by the vibration measurement method according to the first embodiment. The natural frequency may be obtained, for example, by reading the peak of the transmission rate T or by a curve fitting method. The natural frequency extracted when evaluating the vibration characteristics of the tire 11 includes, for example, a cross-sectional primary mode, a cross-sectional secondary mode, and a cavity resonance frequency.

  FIG. 5 is an explanatory diagram showing the relationship between the transmission rate and the frequency. FIG. 5 shows the transmission rate Tp (solid line) obtained by the vibration measurement method according to the first embodiment, the transmission rate To (dashed line) obtained by the conventional vibration measurement method, and the transmission rate Ta obtained by analysis. (One-dot chain line) is shown. In the experiment, tires of 195/70 R14 were used.

  As can be seen from the results of FIG. 5, the transmission rate Tp obtained by the vibration measurement method according to the first embodiment does not show the resonance of the structure support 4 in the vicinity of 290 Hz that appeared in the conventional vibration measurement method. . As a result, the natural frequency of the tire 11 can be clearly extracted. The transmission rate Tp obtained by the vibration measurement method according to the first embodiment shows the same tendency as the transmission rate Ta obtained by analysis.

  6A and 6B are explanatory diagrams illustrating the relationship between the vibration meter mounting position and the excitation (input) direction. The vibration of the tire 11 and the structure support 4 is detected by the first vibrometer 21 attached to the tire 11 and the second vibrometer 22 attached to the structure support 4. Therefore, as shown in FIG. 6A, the direction in which the tire 11 and the structure support 4 vibrate (the direction indicated by the arrow P in FIG. 6A), that is, the input direction for vibration, and the structure A first vibrometer 21 and a second vibrometer 22 are arranged on a plane PV formed by the axis Y of the support 4.

  In this way, the sensitivity directions of the first vibrometer 21 and the second vibrometer 22 are made to coincide with the excitation (vibration) direction. In addition, if it is on the plane PV formed by the input direction for vibration and the axis Z of the structure support body 4, the first vibrometer is applied to the tread portion 11T of the tire 11 on the side facing the vibration direction. 21 may be arranged (the position of the dotted line in FIG. 6-2). Next, a modified example of the vibration measuring apparatus according to the first embodiment will be described.

(Modification)
7A and 7B are schematic diagrams illustrating the configuration of the vibration measuring apparatus according to the modification of the first embodiment. The vibration measuring device 1a shown in FIG. 7-1 and the vibration measuring device 1b shown in FIG. 7-2 use a vibration device (for example, an electromagnetic vibration device or a hydraulic vibration device) 7 as a vibration means. By using such a vibration device 7, vibration can be stably performed, so that evaluation accuracy of vibration characteristics is improved.

  In the vibration measuring device 1a shown in FIG. 7-1, the free end side of the cantilever structure support 4 is vibrated by the vibration device 7, and the vibration measuring device 1b shown in FIG. Both ends of the body 4 are vibrated by the vibration device 7. The input to the structure support 4 by the vibration device 7 may be an input with a constant period and amplitude, such as a sine wave or a square wave, or may be an input with a random period or amplitude. . Further, it may be an impact or a chirp (sine wave sweep).

  The input of the vibration exciter 7 is acquired by the second vibrometer 22 attached to the structure support 4 and input to the vibration level adjusting device 24. When the vibration level (for example, the magnitude of vibration displacement or the magnitude of acceleration) of the structure support 4 by the input of the vibration exciter 7 falls within a predetermined threshold, the vibration analysis device 23 causes the tire 11 and the structure. The vibration of the support 4 is detected and the transmission rate T is obtained. Instead of the second vibrometer 22, a vibrometer used for adjusting the vibration level of the structure support 4 may be prepared separately. Next, an example of a procedure for evaluating the vibration characteristics of the tire 11 using the vibration measuring devices 1a and 1b will be described.

  FIG. 8 is a flowchart illustrating a procedure example of a vibration measurement method when the vibration measurement device according to the modification of the first embodiment is used. When the structure support 4 is vibrated by the vibration device 7, the vibration level of the structure support 4 is set (step S101). This can be realized, for example, by adjusting the output of the vibration device 7 (that is, the input to the structure support 4).

  Next, the vibration device 7 is activated to vibrate the structure support body 4 (step S102). For example, a sine wave is used as the excitation waveform. If the structure support body 4 starts a vibration, the vibration level adjustment apparatus 24 will acquire the vibration of the structure support body 4 from the 2nd vibrometer 22 (step S103). And the vibration level adjustment apparatus 24 compares the vibration level a of the acquired structure support body 4 with the predetermined threshold value as (step S104).

  If a ≧ as (step S104: No), the vibration level of the structure support 4 is reset (step S105), and steps S102 to S104 are repeated until a <as. When a <as (step S104: Yes), the vibration analysis device 23 detects the vibration of the tire 11 and the structure support body 4 and obtains the transmission rate T (step S106).

  By doing in this way, since the influence of the vibration characteristic of the structure support body 4 and the tire 11 can be suppressed as much as possible, and a vibration level can be ensured, the accuracy of the transmission rate T is further improved. It is also possible to evaluate non-linearity due to the difference in vibration level. When the transmission rate T for the frequency is obtained by executing Steps S101 to S106 for a certain frequency, the frequency of vibration applied to the structure support 4 by the vibration device 7 is changed with a predetermined frequency resolution. Steps S101 to S106 are executed for each frequency resolution to determine the transmission rate T. As a result, when the structure support 4 is vibrated, components other than the frequency at which the structure support 4 is vibrated are not used, so that the accuracy in evaluating the vibration characteristics of the tire 11 is improved. In addition, it is preferable to set the vibration level of the structure support body 4 for every frequency. Next, an application example when evaluating the vibration characteristics of the structure using the vibration measurement method according to this embodiment will be described.

(Application example of vibration measurement method according to this embodiment)
9A and 9B are explanatory diagrams illustrating application examples of vibration measurement by the vibration measurement method according to the first embodiment. In the example illustrated in FIG. 9A, the tire 11 is suspended in the air, and the vibration measurement method according to the first embodiment is executed. In this case, the structure support body of the tire 11 which is a structure to be evaluated for vibration characteristics is the wheel 12. An input (arrow P) for excitation is performed on the wheel 12. Then, the vibration of the tire 11 is detected as the vibration of the structure to be evaluated for vibration characteristics, and the vibration of the wheel 12 is detected as the vibration of the structure support. Thus, since the vibration characteristics of the structure can be evaluated even in a suspended state, the convenience of evaluation is improved.

  As in the example illustrated in FIG. 9B, the vibration measurement method according to the first embodiment can be executed even when the tire 11 that is a structure to be evaluated for vibration characteristics is attached to the vehicle body 8. In this case, the structure support of the tire 11 becomes the axle S. In executing the vibration measuring method, the vehicle body 8 is lifted by the jack 9, and the axle S, which is the structure support of the tire 11, is vibrated while the tire 11 is lifted from the ground GL. Thus, since the vibration characteristics of the tire 11 can be evaluated while the tire 11 is attached to the vehicle body 8, the convenience is improved.

  As described above, in the first embodiment, the structure to be evaluated for vibration characteristics is attached to the structure support, the structure support is vibrated to obtain the vibration of the structure support in the vibration unit, and The vibration of the structure is acquired, and the vibration transmissibility of the structure is calculated based on the acquired vibration of the structure support and the vibration of the structure. As a result, in the first embodiment, a large-scale evaluation facility for supporting the structure support is unnecessary, the vibration characteristics of the structure can be easily evaluated, and the evaluation accuracy of the vibration characteristics of the structure can be improved. Note that the configuration disclosed in the first embodiment can be appropriately applied to the following embodiments.

(Embodiment 2)
The second embodiment has substantially the same configuration as that of the first embodiment, but by vibrating the two parts of the structure support that supports the structure to be evaluated for vibration characteristics with two translational components, Vibration component of rotation generated in the structure to be evaluated for vibration characteristics (rotation in a plane formed by the input direction for excitation and the shaft of the structure support. The difference is that it suppresses Other configurations are the same as those of the first embodiment.

  10A and 10B are schematic explanatory diagrams when the vibration measurement method according to the second embodiment is executed by the vibration measurement device according to the second embodiment. FIG. 11 is an explanatory diagram of a vibration component of rotation generated in the tire. Also in the second embodiment, the tire 11 constituting the tire / wheel assembly 10 is a structure to be evaluated for vibration characteristics. The tire 11 is a pneumatic tire.

  The vibration measuring device 1c shown in FIGS. 10-1 and 10-2 has the same configuration as the vibration measuring device 1 (see FIG. 1) described in the first embodiment, but is a structure to be evaluated for vibration characteristics. Two locations (a first excitation point a and a second excitation) that are separated from each other by two predetermined distances in the axial direction (longitudinal direction) of the structure support 4 of the structure support 4 of a tire 11. Shake from point b). For this purpose, the vibration measuring device 1 c includes a first vibration device 7 a and a second vibration device 7 b that vibrate the structure support 4.

  As described above, the first vibration device 7a and the second vibration device 7b can be manufactured at a low cost by applying vibration from two locations separated by a predetermined distance in the axial direction (longitudinal direction) of the structure support body 4. Since a direction oscillating device can be used, it is not necessary to directly apply rotation to the structure support 4. Further, it is preferable to vibrate in the same direction from two places separated by a predetermined distance in the axial direction (longitudinal direction) of the structure support body 4 because the vibration efficiency becomes high and unnecessary vibration force is not generated. Here, in order to effectively suppress the rotation of the structure support body 4 and the tire 11, the distance between the first excitation point a and the second excitation point b is preferably 10 cm or more.

  And the 2nd vibration detection means which detects the vibration of the structure support body 4 detects the vibration of the structure support body 4 by the 1st vibration apparatus 7a (1st vibration apparatus). Vibration detection means) 25a and a second vibration equipment vibration meter (second vibration equipment vibration detection means) 25b for detecting the vibration of the structure support 4 by the second vibration equipment 7b. . Note that the vibration of the tire 11 that is a structure to be evaluated for vibration characteristics is detected by the first vibrometer 21.

  In this way, by providing the first vibration device vibration meter 25a and the second vibration device vibration meter 25b at different positions on the structure support body 4, the vibration component of the rotation of the tire 11 can be detected. it can. And by detecting the vibration component of rotation, it can be determined whether it is in the state suitable for the vibration detection of the tire 11 and the structure support body 4. FIG. That is, if the vibration detected by the first vibration device vibration meter 25a is the same as the vibration detected by the second vibration device vibration meter 25b, a rotational vibration component is generated in the structure support 4. It can be judged that it is not. The first vibration device vibrometer 25a and the second vibration device vibrometer 25b may be inexpensive uniaxial vibration meters.

  The vibration measuring device 1c shown in FIGS. 10-1 and 10-2 vibrates the structure support 4 on one side of the attachment portion (bracket 5) between the structure support 4 and the tire / wheel assembly 10. . Note that the vibration measuring device 1c shown in FIG. 10A has input points (excitation points) of the first excitation device 7a and the second excitation device 7b, that is, the first excitation point a and the second excitation point. The vibration of the structure support 4 is detected at the oscillating point b. In the vibration measuring device 1c shown in FIG. 10-2, the input points (excitation points) of the first excitation device 7a and the second excitation device 7b, that is, the first excitation point a and the second excitation point. The vibration of the structure support body 4 is detected at a location different from the vibration point b. The location where the vibration of the structure support 4 is detected may or may not coincide with the excitation point, and can be appropriately changed depending on the configuration of the vibration measuring device 1c.

  Here, as described in the first embodiment (see FIGS. 6A and 6B), the input direction for vibration (the input directions of the first vibration device 7a and the second vibration device 7b) and The first vibration meter 21 and the second vibration detecting means (the first vibration device vibration meter 25a and the second vibration device vibration meter 25b) are formed on the plane PV formed by the axis Z of the structure support 4. ). In this way, the sensitivity directions of the first vibrometer 21 and the second vibration detecting means are matched with the excitation (vibration) direction (the same applies hereinafter).

  When the structure support 4 is vibrated by the first vibration device 7a and the second vibration device 7b, the vibration component of the rotation of the tire 11, which is the structure whose vibration characteristics are to be evaluated, becomes zero. Then, the first vibration device 7a and the second vibration device 7b are input to the structure support body 4. Then, the vibration X1 (displacement, speed, acceleration) of the tire 11 detected by the first vibrometer 21 and the vibration X2 (displacement, speed) of the structure support body 4 detected by the first vibration device vibration meter 25a. , Acceleration), a transmission rate T = −X1 / X2 (= Xa = Xb) is obtained.

  Instead of the vibration Xa of the structure support body 4 detected by the first vibration device vibration meter 25a, the vibration Xb (displacement) of the structure support body 4 detected by the second vibration device vibration meter 25b. , Speed, acceleration), the transmission rate T = −X1 / Xb. Thus, in this embodiment, the vibration X1 of the tire 11 obtained by exciting the structure support body 4 at a position separated by a predetermined distance in the axial direction thereof, and the vibration X2 of the structure support body 4 The transmission rate T is represented by the ratio (= Xa = Xb).

  The vibration measurement method according to the first embodiment is a vibration component in the rotational direction generated in the structure to be evaluated for vibration characteristics (in the tire 11, rotation around the X axis or Z axis, that is, the tire side surface is tilted) When the vibration component in the R direction shown in FIG. 11 is small enough to be ignored, the transmission rate T can be obtained with high accuracy. This is because even if a structure support that supports the structure to be evaluated for vibration characteristics is vibrated, a vibration component in the rotational direction is almost generated in the structure to be evaluated for vibration characteristics (for example, the tire 11). Because it does not. However, when the vibration component in the rotational direction generated in the structure to be evaluated for vibration characteristics cannot be ignored, the vibration component in the rotational direction affects the transmission factor T, and the accuracy of the transmission factor T is reduced. End up.

  For this reason, in the vibration measuring method according to the second embodiment, the structure support 4 is vibrated so that the vibration component in the rotational direction generated in the structure to be evaluated for vibration characteristics becomes zero. As a result, the influence of the vibration component in the rotational direction generated in the structure to be evaluated for vibration characteristics can be eliminated, and the transmission rate T can be obtained with high accuracy. Next, the concept of the vibration measurement method according to the second embodiment will be described.

  FIG. 12 is an explanatory auxiliary diagram for explaining the vibration measuring method according to the second embodiment. In the vibration measurement method according to the second embodiment, a measurement method equivalent to the conventional vibration measurement method is obtained from the relational expression of the transfer function. The relationship between the input and the output when the tire 11 that is a structure to be evaluated for vibration characteristics is fixed to the structure support 4 and the rotation of the tire 11 (tilt of the side surface of the tire) is taken into consideration is expressed by the formula (2 ). Here, the subscript 1 indicates the vibration of the tire 11, the subscript 2 indicates the translational vibration of the structure support body 4, and the subscript 3 indicates the rotation vibration of the structure support body 4. f represents a force and M represents a moment. X represents translational displacement, and R represents rotational displacement.

In the system of the tire 11 and the structure support 4 shown in FIG. 12, the state of restraining the translational vibration and the rotation vibration of the structure support 4 is X2 = 0 and R3 = 0 in Equation (2). It can be expressed by doing. When equation (2) is solved under these conditions and transmission rate T = f ₂ / f ₁ is obtained, equation (3) is obtained.

Considering the case where vibration is applied to the structure support 4 so that R3 (vibration of rotation of the structure support 4) becomes 0, f ₁ = 0 and R3 = 0 in Equation (2). Therefore, when Equation (2) is solved under this condition, the relationship of Equation (4) and Equation (5) is obtained.

When the transmission rate T in Expression (3) is rewritten using the relationship between Expression (4) and Expression (5), T = −X1 / X2. That is, when translational excitation and rotational excitation are applied to the structure support 4 so that R3 = 0, the transmission rate T of the tire 11 can be obtained by -X1 / X2. Since it is difficult to vibrate the structure support 4 by controlling the rotational component (vibration) so as to cancel M ₃ , translational excitation is applied to two different locations with respect to the axial direction of the structure support 4. By giving this, R3 = 0. Next, this method will be described.

FIGS. 13A and 13B are explanatory diagrams illustrating a vibration method in the vibration measurement method according to the second embodiment. In this embodiment, translational excitation is applied to two different locations with respect to the axial direction of the structure support 4 to cancel M ₃ , and R3 = 0. FIG. 13A shows an example in which the structure support body 4 is vibrated on both sides of the place where the vibration X2 of the structure support body 4 is acquired. When the distance from X2 to the first excitation point a is La, and the distance from X2 to the second excitation point b is Lb, X2 is expressed by Equation (6) and R3 is expressed by Equation (7). Can do. Here, Xa is the vibration (displacement, speed, acceleration) of the first excitation point a, and Xb is the vibration (displacement, speed, acceleration) of the second excitation point b. From Equation (7), in order to set R3 = 0, the first excitation point a and the second excitation point b may be excited so that Xa = Xb (= X2).

  FIG. 13-2 shows an example in which the structure support 4 is vibrated on one side of the location where the vibration X2 of the structure support 4 is acquired. When the distance from X2 to the first excitation point a is La, and the distance from X2 to the second excitation point b is Lb, X2 is expressed by Equation (8) and R3 is expressed by Equation (9). Can do. From Equation (9), in order to set R3 = 0, the first excitation point a and the second excitation point b may be excited so that Xa = Xb (= X2).

  Even when the structure support 4 is vibrated on both sides of the place where the vibration X2 of the structure support 4 is obtained, the structure support 4 is placed on one side of the place where the vibration X2 of the structure support 4 is obtained. Even in the case of excitation, the first excitation point a and the second excitation point b may be applied so that Xa = Xb (= X2). Here, in order to vibrate the first excitation point a and the second excitation point b so that Xa = Xb, for example, the displacement of the first excitation point a and the second excitation point The displacement of the point b is equal, or the velocity of the first excitation point a and the velocity of the second excitation point b are equal, or the acceleration of the first excitation point a and the first It is sufficient to apply vibration so that the acceleration at the second excitation point b is equal. The first vibration device 7a and the second vibration device 7b are controlled so that Xa = Xb. Next, the procedure of the vibration measuring method according to the second embodiment will be described.

  FIG. 14 is a flowchart illustrating a procedure of the vibration measuring method according to the second embodiment. When the structure support 4 is vibrated by the first vibration device 7a and the second vibration device 7b, the vibration levels of the first vibration device 7a and the second vibration device 7b are set (step S201). This can be realized, for example, by adjusting the outputs of the first vibration device 7a and the second vibration device 7b (that is, the input to the structure support 4).

  Next, the 1st vibration apparatus 7a and the 2nd vibration apparatus 7b are started, and the structure support body 4 is vibrated (step S202). For example, a sine wave is used as the excitation waveform. When the structure support 4 starts to vibrate, the vibration level adjusting device 24 transmits the vibration Xa and the first vibration at the first excitation point a from the first vibration device vibration meter 25a and the second vibration device vibration meter 25b. The vibration Xb of the second excitation point b is acquired (step S203). Then, the vibration level adjusting device 24 calculates a difference ΔX between the acquired vibration Xa at the first excitation point a and vibration Xb at the second excitation point b (step S204). Then, the vibration level adjusting device 24 compares the calculated ΔX with a predetermined threshold value ΔXs (step S205).

  If ΔX ≧ ΔXs (step S205: No), the vibration levels of the first vibration device 7a and the second vibration device 7b are reset (step S206), and steps S202 to S202 are performed until ΔX <ΔXs. Step S205 is repeated. When ΔX <ΔXs (step S205: Yes), the vibration analysis device 23 determines whether the vibration X1 of the tire 11 and the vibration Xa of the first excitation point a or the vibration Xb of the second excitation point b are selected. Either one is detected. Then, the vibration analysis device 23 obtains the transmission rate T = X1 / X2 using the detected Xa or Xb as the vibration X2 of the structure support body 4 (step S207). That is, X2 = Xa (or Xb). Note that both Xa and Xb may be detected, and the average value may be used as the vibration X2 of the structure support 4 (X2 = (Xa + Xb) / 2).

  When the transmission rate T for the frequency is obtained by executing steps S201 to S207 for a certain frequency, the structure support 4 by the first vibration device 7a and the second vibration device 7b with a predetermined frequency resolution. The transmission frequency T is obtained by changing the frequency of excitation with respect to and performing steps S201 to S207 for each frequency resolution.

(Modification)
15A and 15B are explanatory diagrams illustrating a vibration measuring apparatus according to a modification of the second embodiment. The vibration measurement device 1d shown in FIGS. 15-1 and 15-2 has the same configuration as the vibration measurement device 1c (see FIGS. 10-1 and 10-2), but the structure support 4 and the tire / The structure support 4 is vibrated on both sides of the mounting portion (bracket 5) with the wheel assembly 10. Note that the vibration measuring device 1d shown in FIG. 15A has input points (excitation points) of the first excitation device 7a and the second excitation device 7b, that is, the first excitation point a and the second excitation point. The vibration of the structure support 4 is detected at the oscillating point b. Further, in the vibration measuring apparatus 1c shown in FIG. 15-2, the input points (excitation points) of the first excitation device 7a and the second excitation device 7b, that is, the first excitation point a and the second excitation point. The vibration of the structure support 4 is detected at a location different from the oscillating point b. The location where the vibration of the structure support 4 is detected may or may not coincide with the excitation point, and can be changed as appropriate depending on the configuration of the vibration measuring device 1d.

  FIG. 16 is an explanatory diagram showing the relationship between the transmission rate and the frequency. In FIG. 16, the transmission rate Tp2 (solid line) obtained by the vibration measurement method according to the second embodiment, the transmission rate Tp1 (broken line) obtained by the vibration measurement method according to the first embodiment, and the analysis obtained. The transmission rate Ta (one-dot chain line) is shown. In the experiment, tires of 195/70 R14 were used.

  As can be seen from the results of FIG. 16, the transmission rate Tp2 obtained by the vibration measurement method according to the second embodiment appears at the transmission rate Tp1 obtained by the vibration measurement method according to the first embodiment in the vicinity of 200 Hz. An undesirable peak disappears, and the transmission rate T of the tire can be evaluated more accurately. Further, the transmission rate Tp2 obtained by the vibration measurement method according to the second embodiment shows the same tendency as the transmission rate Ta obtained by analysis.

  As described above, in Embodiment 2, the rotation generated in the structure to be evaluated for vibration characteristics by exciting the structure support that supports the structure to be evaluated for vibration characteristics with two translational components. Suppresses vibration components. As a result, in the second embodiment, a large-scale evaluation facility for supporting the structure support is not required, and the vibration characteristics of the structure can be easily evaluated. Further, the vibration component of the rotation of the structure is suppressed, and the structure The evaluation accuracy of the vibration characteristics can be further improved.

  As described above, the vibration measuring method and the vibration measuring apparatus according to the present invention are useful for evaluating the vibration characteristics of a structure, and in particular, the vibration characteristics of the structure can be easily evaluated and the object for evaluating the vibration characteristics. It is suitable for improving the evaluation accuracy of the vibration characteristics by reducing the influence of resonance of the structure support that supports the structure.

It is a schematic explanatory drawing at the time of performing the vibration measuring method which concerns on Embodiment 1 with the vibration measuring device which concerns on Embodiment 1. FIG. It is explanatory drawing which shows the conventional vibration measuring method. It is explanatory drawing which shows the vibration experiment which vibrates the structure support body of a tire using the installation which performs the conventional vibration measuring method. It is explanatory drawing which shows an example of the transmission rate obtained by the conventional vibration measuring method. It is explanatory drawing which shows an example of the transmissivity obtained as a result of vibrating the structure support body of a tire / wheel assembly using the equipment which performs the conventional vibration measuring method. It is a conceptual diagram explaining the idea of the vibration measuring method which concerns on Embodiment 1. FIG. It is explanatory drawing which shows the relationship between a transmission rate and a frequency. It is explanatory drawing which shows the relationship between the attachment position of a vibrometer and an excitation (input) direction. It is explanatory drawing which shows the relationship between the attachment position of a vibrometer and an excitation (input) direction. It is the schematic which shows the structure of the vibration measuring apparatus which concerns on the modification of Embodiment 1. FIG. It is the schematic which shows the structure of the vibration measuring apparatus which concerns on the modification of Embodiment 1. FIG. 6 is a flowchart illustrating an example of a procedure of a vibration measurement method when a vibration measurement device according to a modification of the first embodiment is used. 6 is an explanatory diagram illustrating an application example of vibration measurement by the vibration measurement method according to the first embodiment. FIG. 6 is an explanatory diagram illustrating an application example of vibration measurement by the vibration measurement method according to the first embodiment. FIG. It is a schematic explanatory drawing at the time of performing the vibration measuring method which concerns on Embodiment 2 with the vibration measuring device which concerns on Embodiment 2. FIG. It is a schematic explanatory drawing at the time of performing the vibration measuring method which concerns on Embodiment 2 with the vibration measuring device which concerns on Embodiment 2. FIG. It is explanatory drawing of the vibration component of the rotation which generate | occur | produces in a tire. FIG. 10 is an explanatory auxiliary diagram for explaining a vibration measuring method according to the second embodiment. FIG. 10 is an explanatory diagram illustrating a vibration method in the vibration measurement method according to the second embodiment. FIG. 10 is an explanatory diagram illustrating a vibration method in the vibration measurement method according to the second embodiment. 6 is a flowchart illustrating a procedure of a vibration measurement method according to the second embodiment. It is explanatory drawing which shows the vibration measuring device which concerns on the modification of Embodiment 2. It is explanatory drawing which shows the vibration measuring device which concerns on the modification of Embodiment 2. It is explanatory drawing which shows the relationship between a transmission rate and a frequency.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a, 1b, 1c Vibration measuring device 2 Apparatus base 3 Structure support fixing tool 4 Structure support 5 Bracket 6 Hammer 7 Excitation equipment 7a First excitation equipment 7b Second excitation equipment 8 Car body 9 Jack 10 Tire / Wheel Assembly 11 Tire 11T Tread 12 Wheel 21 First Vibrometer 22 Second Vibrometer 23 Vibration Analyzing Device 24 Vibration Level Adjusting Device 25a First Vibrating Device Vibrometer 25b Second Vibrating Device Vibrometer

Claims (13)

A procedure for exciting a structure support that supports a structure to be evaluated for vibration characteristics;
Obtaining a vibration of the structure support and a vibration of the structure in a plane including an axis of the structure support and a direction of exciting the structure support;
A procedure for calculating a vibration transmissibility of the structure based on a ratio of the acquired vibration of the structure and vibration of the structure support;
The vibration measuring method characterized by including.   The vibration measuring method according to claim 1, wherein the structure support is vibrated by a vibration device.   2. When the structure support is vibrated, two different places of the structure support are vibrated, and the directions of vibration at the respective vibration places are parallel to each other. The vibration measuring method as described.   Vibration detecting means is provided at two locations separated in the axial direction of the structure support, and a vibration component of rotation in a plane including the axis of the structure support and the direction of excitation is detected. The vibration measuring method according to claim 3.   When the difference between the vibrations at the two different locations falls within a predetermined threshold, the vibration of the structure and the vibration of the structure support are acquired and the vibration transmissibility is calculated. The vibration measuring method according to claim 4.   It comprises two vibration devices that vibrate the structure support, and the vibration component of the rotation is suppressed by controlling the vibration force of at least one vibration device. The vibration measuring method according to any one of claims 3 to 5. While vibrating with a sine wave to obtain the vibration of the structure and the vibration of the structure support,
The frequency of the sine wave is changed with a predetermined frequency resolution, and the vibration of the structure and the vibration of the structure support are obtained for each frequency resolution. The vibration measuring method according to claim 1.   The vibration measurement method according to claim 1, wherein the vibration level of the structure support is adjusted to a predetermined magnitude based on the acquired vibration of the structure support.   The vibration measuring method according to claim 1, wherein the structure is a tire or a tire / wheel assembly.   In a state where the tire or the tire / wheel assembly is attached to a vehicle, vibration of the tire or the tire / wheel assembly is performed in a state where the tire constituting the tire or the tire / wheel assembly is floated from the ground. The vibration measurement method according to claim 9, wherein measurement is performed. A structure support that supports the structure to be evaluated for vibration characteristics; and
Vibration means for vibrating the structure support;
First vibration detecting means for detecting vibration of the structure;
Second vibration detecting means for detecting vibration of the structure support;
Vibration for calculating the vibration transmissibility of the structure based on the ratio of the vibration of the structure support acquired from the second vibration detection means and the vibration of the structure acquired from the first vibration detection means An analysis device;
A vibration measuring device comprising: A structure support that supports the structure to be evaluated for vibration characteristics; and
A first vibration exciter for exciting the structure support;
A second vibration device that vibrates the structure support by inputting the structure support in a direction parallel to the first vibration device;
First vibration detecting means for detecting vibration of the structure;
Second vibration detecting means for detecting vibration of the structure support;
Vibration for calculating the vibration transmissibility of the structure based on the ratio of the vibration of the structure support acquired from the second vibration detection means and the vibration of the structure acquired from the first vibration detection means An analysis device;
A vibration measuring device comprising: The second vibration detecting means is provided at two locations separated in the axial direction of the structure support, and the vibration for the first vibration device detects the vibration of the structure support by the first vibration device. A detection means; and a vibration detection means for a second vibration device that detects vibration of the structure support by the second vibration device; and
The vibration measuring apparatus according to claim 12, wherein the vibration of the structure support is detected by at least one of the vibration detecting means for the first vibration device and the vibration detecting means for the second vibration device. .

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