JP3289810B2 - Propeller shaft balance measuring device and balance measuring method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for measuring the balance of a propeller shaft used for measuring the balance of a propeller shaft mounted on a vehicle in a final test line of an automobile manufacturing process. .

[0002]

2. Description of the Related Art FIG. 7 shows an example of this type of propeller shaft balance measuring device.

On the vehicle body side, a first propeller shaft 103 is connected to an extension 101 of the transmission via a joint 102, and a second propeller shaft 106 is connected to a center bearing 104 of the first propeller shaft 103 via a joint 105. Is connected. The second propeller shaft 106 is connected to a differential gear case 108 via a joint 107.
Connected to

The balance measuring device includes a reflection tape 109 adhered to a second propeller shaft 106 and a reflection tape 1.
09, a rotation sensor 110 such as an optical fiber sensor for detecting the rotation speed of the second propeller shaft 106 by detecting the reflected wave, a rotation sensor amplifier 111 for converting the output of the rotation sensor 110 into a voltage output, and a differential gear. An acceleration sensor 112 attached to a lower portion of the case 108 with a magnet;
3 and a balance calculation device 114.

In the above-described balance measuring device, the rotation sensor amplifier 111 outputs a pulse voltage having a cycle corresponding to the rotation speed as shown in FIG. When this signal is Fourier-transformed by the balance calculator 114, FIG.
As shown in (b), if the rotation speed is constant, a peak spectrum occurs at a predetermined frequency fp. Similarly, a voltage signal as shown in FIG. 9A is output from the acceleration sensor amplifier 113, and a Fourier transform of the voltage signal produces a peak spectrum at a predetermined frequency fp as shown in FIG. 9B.

The Fourier transform result of the light pulse shown in FIG. 8 is expressed by the following equation (1), and the Fourier transform result of the acceleration sensor signal shown in FIG. 9 is expressed by the following equation (2). Can be obtained by the following equation (3).

Fx (ω) = a + jb | Fx (ω) | = √ (a ² + b ² ) Formula 1 Fy (ω) = c + jd | Fy (ω) | = √ (c ² + d ² ) Formula 2 θ ₁ = tan ^-1 (ad-bc) / (ac + bd) Equation 3 The above measurement is performed twice by exchanging the dummy weight attached to the propeller shaft (for example, when the angle at which the dummy weight is attached is 0 ° and 180 °). and measurement), as shown in FIG. 10, the size is | Fy ₁ (ω) | in the vector of the phase angle theta _1, magnitude | Fy ₂ (omega) | in the phase angle of two theta ₂ And a half of these combined vectors is an unbalanced vector of the propeller shaft. Therefore, if a balance weight having a magnitude and a phase angle θx corresponding to the vector W in the opposite direction to the composite vector is attached to the propeller shaft,
The imbalance of the propeller shaft is eliminated.

However, the two-point method as described above requires a lot of man-hours for inspection. Therefore, it is not very practical when, for example, the balance of a propeller shaft is measured in a factory inspection line while the vehicle is in an actual vehicle state. . Therefore, in the case of the inspection of the actual vehicle state, the following simple measurement method is used.

That is, as shown in FIG. 11, since there is a substantially linear relationship between the unbalance amount of the propeller shaft of the vehicle and the peak value of the vibration acceleration of the differential gear case, the vibration acceleration of the differential gear case By measuring the peak value at the propeller shaft rotation speed, the amount of imbalance can be roughly estimated. According to this method, the measurement is completed in one measurement,
Since there is no need to replace dummy weights, the number of steps can be significantly reduced.

[0010] Further, since the approximate amount of imbalance is determined depending on the vehicle type or specification, characteristics for each vehicle type or specification (FIG. 11 shows A type, B type and C type).
When the balance is measured in advance, the amount of imbalance in the normal range of the vehicle type can be immediately determined by determining the vehicle type and specifications with a card reader or the like at the time of balance measurement, so the propeller shaft of the vehicle is determined from the measurement result. It is possible to immediately determine whether the balance state is normal.

[0011] Such techniques include, for example,
There is one described in JP-A-4-160333.

[0012]

However, in the above-described conventional balance measurement of the propeller shaft, the primary rotational vibration level (the amount of unbalance) of the propeller shaft is equal to or less than the determination value. "Muffled noise" may occur in the vehicle.

[0013] That is, the "muffled sound" is generated when the propeller shaft is unbalanced, generates primary rotation vibration, and the vibration is transmitted from the differential gear case to the vehicle body panel via the suspension or the like. However, even when the primary vibration level of the propeller shaft is equal to or less than the determination value, if there is a peak of the rotational vibration of the tire as vibration from another vibration source near the primary vibration frequency, the There is a problem in hearing that the sound of the muffled sound is felt from the sum of the vibration of the propeller shaft and the vibration of the tire, which may impair the comfort of the vehicle interior. It was an issue.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances, and it is an object of the present invention to obtain a state free of "muffled sound" generated by vibration of a propeller shaft and vibration from another vibration source. It is an object of the present invention to provide a balance measuring device and a balance measuring method for a propeller shaft.

[0015]

According to a first aspect of the present invention, there is provided an apparatus for measuring the balance of a propeller shaft mounted in a measurement area for driving a vehicle. Rotation detection means for detecting rotation of the propeller shaft, vibration detection means for detecting acceleration of vibration of the differential gear case, vibration state detection means for detecting a vibration state in a predetermined frequency range in a signal of the vibration detection means, vibration state Determining means for comparing the output of the detecting means with a preset threshold value based on the vehicle type information data; and a propeller shaft when the determining means determines that the output of the vibration state detecting means is equal to or greater than the threshold value. And a calculating means for detecting an unbalance amount and a phase of the signal.
The predetermined frequency range in the signal of the vibration detecting means is configured to be the rotation frequency of the propeller shaft ± 30 Hz, and the predetermined frequency range in the signal of the vibration detecting means is configured to be 20 to 100 Hz.
According to a fourth aspect, the output of the vibration state detecting means is an effective value of the vibration in a predetermined frequency range in the signal of the vibration detecting means, and the threshold value is set in advance in the cabin based on the vehicle type information data. The configuration is determined based on the relationship with the level, and the above configuration is used as means for solving the problem.

According to a fifth aspect of the present invention, there is provided a method for measuring the balance of a propeller shaft according to a fifth aspect of the present invention. The acceleration of the vibration of the case is detected, and the output of the vibration state in a predetermined frequency range in the detection result is compared with a threshold set in advance based on the vehicle type information data to determine the output of the vibration state. In the above case, the unbalance amount and the phase of the propeller shaft are detected, and the output of the vibration state in the predetermined frequency range in the detection result of the acceleration of the vibration of the differential gear case is the power in the predetermined frequency range. The effective value obtained from the square root of the sum of the spectra, The threshold value is determined based on a relationship with a preset vibration level in the vehicle cabin based on the vehicle type information data. When measuring the balance, the acceleration of the vibration of the differential gear case is detected during rotation of the propeller shaft, the vibration power spectrum at the primary rotation frequency of the propeller shaft is detected from the detection result, and the differential corresponding to the vehicle type information data is detected. The tire rotation frequency is detected from the gear ratio, the vibration power spectrum at the tire rotation frequency near the primary rotation frequency of the propeller shaft is detected, and the vibration power spectrum at the primary rotation frequency of the propeller shaft and the vehicle type information data are obtained. Based on the preset propeller shaft A comparison is made between the threshold value of the primary rotation frequency and a vibration power spectrum at the tire rotation frequency and a threshold value of the tire rotation frequency set in advance based on the vehicle type information data. When the power spectrum is equal to or larger than each threshold value, the unbalance amount and the phase of the propeller shaft are detected, and the above configuration is used as means for solving the problem.

[0017]

In the propeller shaft balance measuring apparatus according to the first aspect of the present invention, the vibration state detecting means uses the vibration state within a predetermined frequency range in the signal of the vibration detecting means of the differential gear case. The rotation frequency of the described propeller shaft ± 30H
z, or a vibration state in a frequency range that can be felt as a muffled sound, such as 20 to 100 Hz as described in claim 3, and at this time, a vibration in a predetermined frequency range in the signal of the vibration detection means as in claim 4 An effective value of the vibration is detected, and a determination means determines the output (effective value) of the vibration state detecting means and a threshold value set in advance based on the vehicle type information data, for example, based on the vehicle type information data according to claim 4. A comparison is made with a threshold value determined based on a relationship with a predetermined vibration level in the vehicle interior, and when the determination means determines that the output of the vibration state detection means is equal to or greater than the threshold value, When it is determined that a muffled sound that may impair the performance is generated, the arithmetic unit determines whether the propeller shaft is unlocked based on signals from the rotation detection unit and the vibration detection unit. So that the lance amount and the phase is detected.

In the method for measuring balance of a propeller shaft according to a fifth aspect of the present invention, a vibration state in a predetermined frequency range in a signal of a vibration detection means of a differential gear case, that is, a vibration state in a frequency range felt as muffled sound is detected. At this time, the output of the vibration state in the predetermined frequency range in the detection result of the acceleration of the vibration of the differential gear case is detected as the effective value obtained from the square root of the sum of the power spectrum in the predetermined frequency range. And the vibration state (effective value)
For example, a threshold value determined based on the relationship with the vibration level in the vehicle interior set based on the vehicle type information data according to claim 6 is compared and determined as a threshold value preset based on the vehicle type information data. When it is determined that the output of the vibration state is equal to or higher than the threshold, that is, when it is determined that a muffled sound that may impair comfort in the vehicle is generated, the unbalance amount and phase of the propeller shaft are detected. It will be.

Further, according to the propeller shaft balance measuring method of the present invention, when the vibration source other than the propeller shaft is a tire, comfort in the vehicle is obtained by the sum of the vibration of the propeller shaft and the vibration of the tire. When it is determined that a muffled sound that may impair the performance is generated,
The unbalance amount and the phase of the propeller shaft are detected.

[0020]

1 to 4 show an embodiment of a propeller shaft balance measuring device according to claims 1 to 4 of the present invention, and a propeller shaft balance measuring method according to claims 5 and 6 of the present invention. FIG.

The balance measuring device, as shown in FIG.
A rotation sensor 1 as rotation detection means for detecting the rotation speed of the propeller shaft; an acceleration sensor 2 as vibration detection means for detecting acceleration of vibration of the differential gear case; a start switch 3; A vehicle type information detecting means 4 for taking in information data is provided.

The rotation sensor 1 is composed of, for example, an optical fiber for detecting a reflected wave of a reflection tape (see FIG. 7) adhered to a propeller shaft. Also, the acceleration sensor 2
Is attached to a differential gear case by a magnet. Outputs from the rotation sensor 1 and the acceleration sensor 2 are converted into voltage outputs by the rotation sensor amplifier 5 and the acceleration sensor amplifier 6, and further, after the high-frequency components (for example, 200 Hz or more) are removed by the low-pass filter 7, Will be entered.

The start switch 3 and the vehicle type information detecting means 4 are directly connected to the microcomputer 8.
Note that a bar code reader, for example, is used as the vehicle type information detecting means 4.

Further, the balance measuring device includes a rotation sensor 1 and an acceleration sensor 2 in a microcomputer 8.
An A / D converter 9 for converting an analog signal from a digital signal into a digital signal, a vibration state detecting means 10 for detecting a vibration state of a signal of the acceleration sensor 2 within a predetermined frequency range,
Determining means 11 for comparing the output of the vibration state detecting means 10 with a preset threshold based on the vehicle type information data from the vehicle type information detecting means 4; An arithmetic means 12 for detecting the unbalance amount and the phase of the propeller shaft when it is determined that the difference is equal to or larger than the threshold value is provided. Means 13 is connected.

Here, as shown in FIG. 2, when there is a peak Tp of the quaternary rotation of the tire as another excitation source near the peak Pp of the primary rotation of the propeller shaft, for example, Muffled sound is generated by the sum of Therefore, the predetermined frequency range f1 to f2 detected by the vibration state detecting means 10 is defined as the frequency range of the muffled sound generated by the sum of the vibration of the propeller shaft and the vibration of another vibration source (tire), and the rotation frequency of the propeller shaft. ± 30H
The range of z or the range of 20 to 100 Hz. The output of the vibration state detecting means 10 calculates the sum Sp of power spectra in a predetermined frequency range f1 to f2, and obtains an effective value Rp (Rp = √S
Use p).

Further, as shown in FIG. 3, the judging means 11 sets the vibration level (effective value Rp) of the differential gear case in a predetermined frequency range f1 to f2 as a threshold value set in advance based on the vehicle type information data. And a threshold value α1 determined based on a relationship between the vehicle interior vibration level (muffled sound) and a preset vehicle interior vibration level based on the vehicle type information data,
If the effective value Rp is equal to or less than the threshold value, the muffled sound level is good (OK). If the effective value Rp is equal to or more than the threshold value, the muffled sound level is bad (NG).

Next, the operation of the above-described propeller shaft balance measuring device and the balance measuring method will be described with reference to the flowchart shown in FIG.

When the power of the measuring device is turned on, the vehicle type information data is read from the vehicle type information detecting means 4 in step S1. Thereafter, the vehicle equipped with the rotation sensor 1 and the acceleration sensor 2 is brought into a running state by a free roller or the like.
When the speed reaches 00 km / h, the start switch 3 is turned on in step 2.

When the start switch 3 is turned on, the signals of the rotation sensor 1 and the acceleration sensor 2 are A / D converted at a predetermined sampling period (for example, 2 msec) and written into the memory at step S3. When it is confirmed that the rotation data and the vibration data have been obtained, the rotation data and the vibration data are Fourier-transformed in steps S5 and S6, and the rotation power spectrum and the vibration power spectrum are calculated.

Next, in step S7, the sum Sp of the power spectrum between the predetermined frequency ranges f1 and f2 in the vibration power spectrum of the differential gear case (see FIG. 2) is obtained, and the effective value Rp is calculated from the square root thereof. In step S8, a threshold value (see FIG. 3) α1 of the vehicle interior vibration level (muffled sound) corresponding to the vehicle type (specification) is read from the vehicle type information data in step S1, and an effective value Rp and a threshold value α1 are determined in step S9.
Are compared and determined.

Then, in step S9, Rp ≧ α
When it is determined that it is not 1 (NO), it is determined that the unbalance amount of the propeller shaft is equal to or less than the specified value and that no muffled sound is generated in the vehicle, and the measurement is terminated.
This measurement result is shown on the output means shown in FIG.

In step S9, Rp ≧ α1
(YES), step S10
, A primary rotational frequency fp of the propeller shaft is detected, a vibration power spectrum Pd at the primary rotational frequency fp is detected at step S11, and a phase difference between the rotational and vibration signals at the primary rotational frequency fp is detected at step S12. θd is detected.

Then, in step S13, the unbalance coefficient β1 corresponding to the vehicle type information data is read from the memory, and in step S14, the unbalance amount Un
(Pd × β1) calculates the read phase correction amount theta _.beta.1 corresponding to vehicle type information data in step S15 from the memory, the imbalance phase in step S16 .theta.u
_(Θd + θ β1) calculates the unbalance correction amount in step S17 Wu and correction phase θs (θs = θu
± 180 °), the imbalance correction amount Wu and the correction phase θs are displayed in step S18, and the measurement ends. The balance weight is attached according to the measurement result.

As described above, in the balance measuring apparatus and the balance measuring method of this embodiment, the unbalance amount and the phase of the propeller shaft are detected, and the vibration of the propeller shaft and the vibration from other vibration sources such as tires are detected. Can be corrected to a state without the "muffled sound" generated by the above.

In the above embodiment, the frequency analysis by the Fourier transform is performed.
Using a band-pass filter with cut-off frequency
It is also possible to determine the effective value from the analog signal after passing.

FIGS. 5 and 6 are flow charts for explaining a method for measuring the balance of a propeller shaft according to claim 7 of the present invention. The balance measurement method is
The present invention can be implemented in a device similar to the device described in the previous embodiment (see FIG. 1).

When the power is turned on, the vehicle type information data is read in step S21, and thereafter, the vehicle equipped with the rotation sensor and the acceleration sensor is set in a running state by a free roller or the like. When it reaches 100 km / h, step 2
In step 2, the start switch is turned on.

When the start switch is turned on, the signals of the rotation sensor and the acceleration sensor are output to A / A at a predetermined sampling cycle (for example, 2 msec) in step S23.
D-converted and written in the memory, and when it was confirmed that the sampling number became 1024 in step S24, the rotation data and the vibration data were Fourier-transformed in steps S25 and S26, respectively.
Calculate rotation power spectrum and vibration power spectrum.

Next, in step S27, the primary rotational frequency fp of the propeller shaft is detected, and in step S28
After detecting the vibration power spectrum Pd at the same rotation primary frequency fp in step S29, the differential gear ratio Gr corresponding to the vehicle type information data is read out and the tire rotation n-order frequency ft ( ft = fp / Gr).

In step S30, a frequency nft (n = 1) obtained by multiplying the nth frequency ft of the tire rotation by an order is obtained.
-10), a tire rotation frequency ftp near the primary rotation frequency fp of the propeller shaft is detected, and step S31 is performed.
In step S32, the vibration power spectrum Ptp at the tire rotation frequency ftp is detected, and in step S32, a threshold α2 of the primary rotation frequency of the propeller shaft and a threshold α3 of the nth rotation of the tire corresponding to the vehicle type information data are determined. read out.

Thereafter, in step S33, the vibration power spectrum Pd at the primary rotation frequency fp of the propeller shaft in step S28 is compared with the threshold α2 of the primary rotation frequency of the propeller shaft, and the next step is performed. In S34, vibration power spectrum Ptp at tire rotation frequency ftp in step 31
And a threshold α3 of the nth order frequency of the tire rotation.

At this time, in step S33, Pd ≧
If it is determined that it is not α2 (NO), and if it is further determined in step 34 that Ptp ≧ α3 (NO), it is determined that the unbalance amount of the propeller shaft is equal to or less than the specified value and that the muffled noise in the vehicle is small. Judge,
In step S35, it is displayed that there is no problem in the vibration level, and the measurement is completed.

Steps S33 and S34
In any of the above, when it is determined that Pd ≧ α2 (YES) or Ptp ≧ α3 (YES), it is determined that there is a problem in the vibration level and whether the balance of the propeller shaft was previously corrected in S36 or not. Is determined. This is because if there is a problem in the vibration level in the first measurement, the balance measurement is performed again after correcting the unbalance of the propeller shaft.

If it is determined in step S36 that the balance of the propeller shaft has not been previously corrected (NO), the phase difference θd between the rotation and vibration signals at the same rotation primary frequency fp is detected in step S37. In step S38, the unbalance coefficient β2 corresponding to the vehicle type information data is read from the memory, the unbalance amount Un (Pd × β2) is calculated in step S39, and the phase correction amount _θβ2 corresponding to the vehicle type information data is stored in step S40. From step S
Calculated imbalance phase _θu (θd + θ β2) at 41, the unbalance correction amount W in step S42
u and the correction phase θs (θs = θu ± 180 °) are calculated, and in step S42, the unbalance correction amount Wu and the correction phase θs are displayed, and the measurement is completed. The balance weight is attached according to the measurement result.

If it is determined in the previous step S36 that the balance of the propeller shaft has been corrected last time (YES), there is a problem with the vibration source other than the propeller shaft, that is, the balance of the tire. , The correction display of the tire balance is performed, and the measurement is completed.

That is, in the method of measuring the balance of the propeller shaft in this embodiment, the unbalance amount and phase of the propeller shaft are detected, and are generated by the vibration of the propeller shaft and the vibration from another vibration source such as a tire. In addition to correcting the muffled sound, it is also possible to detect the tire vibration amplitude (for example, primary) outside the muffled sound area. Is possible.

[0047]

As described above, according to the propeller shaft balance measuring device according to the first aspect of the present invention, the vibration is generated by the propeller shaft unbalance and other vibration sources such as the tire unbalance. This makes it possible to measure the vibration of the vehicle, which contributes to the prevention of the occurrence of muffled sound, and significantly enhances the comfort of the passenger compartment.

Further, as in the propeller shaft balance measuring device according to the second and third aspects of the present invention, a predetermined frequency range used for detecting the vibration state by the vibration state detecting means is set. As in the related propeller shaft balance measuring device, the output of the vibration state detecting means is set as the effective value of the vibration in a predetermined frequency range in the signal of the vibration detecting means, and the threshold value is set in advance in the cabin based on the vehicle type information data. And the vibration level generated by other vibration sources such as the unbalance of the propeller shaft and the unbalance of the tire can be measured more reliably.

According to the method of measuring balance of a propeller shaft according to the fifth aspect of the present invention, as in the first aspect, the vibration generated by other excitation sources such as the unbalance of the propeller shaft and the tire is unbalanced. Can be measured, which can contribute to the prevention of muffled noise caused by the vibration, and can significantly enhance the comfort of the vehicle interior. According to the balance measuring method for a propeller shaft according to claim 6, It is possible to easily and more reliably measure the vibrations generated by other vibration sources such as the unbalance of the propeller shaft and the tire.

Further, according to the propeller shaft balance measuring method according to the seventh aspect of the present invention, the same effect as that of the fifth aspect can be obtained, and the tire balance can be simply measured. Also, it can contribute to improvement of inspection accuracy and improvement of work efficiency in the inspection process.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an embodiment of a propeller shaft balance measuring device according to claims 1 to 4 of the present invention.

FIG. 2 is a graph showing a relationship between a propeller shaft rotation frequency and a vibration power spectrum of a differential gear case.

FIG. 3 is a graph showing a relationship between a vibration level of a differential gear case and a vehicle interior vibration level in a predetermined frequency range.

FIG. 4 shows the operation of the propeller shaft balance measuring device according to claims 1 to 4 of the present invention, and claim 5 of the present invention.
9 is a flowchart illustrating a method for measuring balance of a propeller shaft according to the first and sixth embodiments.

FIG. 5 is a flowchart illustrating a method for measuring balance of a propeller shaft according to claim 7 of the present invention.

FIG. 6 is a flow chart for explaining a method of measuring balance of a propeller shaft according to claim 7 of the present invention, which is continued from FIG. 5;

FIG. 7 is a block diagram schematically showing a conventional propeller shaft balance measuring device.

8A is a graph showing the output of the rotation sensor, and FIG. 8B is a graph showing the relationship between the frequency and the gain after Fourier transform.

9A is a graph showing the output of the acceleration sensor, and FIG. 9B is a graph showing the relationship between the frequency after Fourier transform and the gain.

FIG. 10 is an explanatory diagram when an unbalance amount and a phase are obtained by a two-point method.

FIG. 11 is a graph showing the relationship between the unbalance amount of the propeller shaft and the vibration amplitude of the differential gear case of the primary rotation of the propeller shaft for different vehicle types.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotation sensor (rotation detection means) 2 Acceleration sensor (vibration detection means) 10 Vibration state detection means 11 Judgment means 12 Calculation means

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-6-201506 (JP, A) JP-A-6-214015 (JP, A) JP-A-6-273253 (JP, A) JP-A-5-2015 288631 (JP, A) JP-A-63-138230 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01M 1/22 G01H 3/08

Claims (7)

(57) [Claims] 1. A device for measuring the balance of a propeller shaft mounted in a measurement area for setting a vehicle in a running state, wherein the rotation detecting means detects rotation of the propeller shaft, and detects acceleration of vibration of a differential gear case. Vibration detection means, a vibration state detection means for detecting a vibration state within a predetermined frequency range in a signal of the vibration detection means, and a comparison between an output of the vibration state detection means and a preset threshold based on vehicle type information data. A propeller shaft, comprising: a judging means for judging; and a calculating means for detecting an unbalance amount and a phase of the propeller shaft when the judging means judges that the output of the vibration state detecting means is equal to or more than a threshold value. Balance measuring device. 2. The propeller shaft balance measuring device according to claim 1, wherein a predetermined frequency range of the signal of the vibration detecting means is a rotation frequency of the propeller shaft ± 30 Hz. 3. The balance measuring device for a propeller shaft according to claim 1, wherein the predetermined frequency range of the signal of the vibration detecting means is 20 to 100 Hz. 4. An output of the vibration state detecting means is an effective value of a vibration in a predetermined frequency range in a signal of the vibration detecting means, and a threshold value is set based on vehicle type information data. The propeller shaft balance measuring apparatus according to any one of claims 1 to 3, wherein the apparatus is determined based on a relationship with a level. 5. When measuring the balance of a propeller shaft mounted on a vehicle in a measurement area where the vehicle is in a running state, acceleration of vibration of a differential gear case during rotation of the propeller shaft is detected. Comparing the output of the vibration state with a preset threshold value based on the vehicle type information data, and detecting the unbalance amount and phase of the propeller shaft when the output of the vibration state is equal to or greater than the threshold value. A balance measuring method for a propeller shaft, characterized in that: 6. An output of a vibration state in a predetermined frequency range in a detection result of acceleration of vibration of a differential gear case is an effective value obtained from a square root of a sum of power spectra in a predetermined frequency range, and a threshold value is:
6. The balance measuring method for a propeller shaft according to claim 5, wherein the balance is determined based on a relationship with a preset vibration level in the vehicle interior based on the vehicle type information data. 7. When measuring the balance of a propeller shaft mounted on a vehicle in a measurement area where the vehicle is running, the acceleration of vibration of a differential gear case is detected when the propeller shaft rotates, and the rotation of the propeller shaft is determined based on the detected result. In addition to detecting the vibration power spectrum at the primary frequency, the tire rotation frequency is detected from the differential gear ratio corresponding to the vehicle type information data, and the vibration power spectrum at the tire rotation frequency near the primary rotation frequency of the propeller shaft is calculated. Detecting and comparing the vibration power spectrum at the primary rotation frequency of the propeller shaft with a threshold value of the primary rotation frequency of the propeller shaft set in advance based on the vehicle type information data,
Furthermore, a comparison is made between a vibration power spectrum at the tire rotation frequency and a preset threshold value of the tire rotation frequency based on the vehicle type information data, and when each vibration power spectrum is equal to or more than each threshold value, A method for measuring balance of a propeller shaft, comprising detecting an unbalance amount and a phase of the propeller shaft.