JP6133898B2 - Inspection method for vehicle seat drive mechanism - Google Patents

Description

  The present invention relates to a drive mechanism for a vehicle seat such as an automobile, and more particularly to a vehicle seat drive mechanism inspection apparatus and a computer program for determining the quality of a power unit for driving an electric power seat.

  Patent Document 1 discloses a method for determining an abnormal noise that detects an abnormal noise of a seat slider that is one of vehicle drive mechanisms. This is a technique for detecting the operation sound during operation of the seat slider with a sensor, calculating the change amount of the operation sound per unit time, and comparing the change amount with a threshold value to determine the presence or absence of abnormal noise.

JP 2009-198284 A

  However, since Patent Document 1 is configured to detect the operation sound of the seat slider with a sensor, accurate measurement is difficult unless a predetermined soundproof environment suitable for detecting the operation sound. Therefore, it is unsuitable for inspection at the site where the vehicle seat is actually assembled, and development of a technique capable of accurately and simply measuring abnormal noise at the vehicle seat assembly site has been desired.

  The present invention has been made in view of the above, and it is possible to more accurately perform the quality of the drive mechanism of the vehicle seat without detecting the operation sound, thereby more accurately determining the non-defective product / defective product. It is an object of the present invention to provide a vehicle seat drive mechanism inspection apparatus and a computer program that can be used.

  In order to solve the above problems, a vehicle seat drive mechanism inspection device according to the present invention is a vehicle seat drive mechanism inspection device that determines the quality of a vehicle seat drive mechanism, and includes a predetermined mechanism of the drive mechanism. The vibration sensor attached to the measurement point and the detection signal detected by the vibration sensor when the drive mechanism is driven are analyzed to determine the presence or absence of abnormal noise. The quality of the drive mechanism is determined based on the presence or absence of the abnormal noise. And an analysis determination unit that determines whether or not

  It is preferable that the analysis determination unit is configured to frequency-analyze a detection signal obtained from the vibration sensor and determine the presence / absence of the abnormal noise based on the presence / absence of irregular vibration. It is preferable that the analysis determination unit is configured to determine the presence or absence of the irregular vibration by comparing power spectra of harmonic components of the fundamental frequency in the frequency analysis result. It is preferable that the analysis determination unit is configured to determine the presence / absence of the irregular vibration in addition to the presence / absence of a predetermined characteristic frequency component in the frequency analysis result. It can be suitably used when the drive mechanism is a power unit of an electric power seat.

  The computer program of the present invention is attached to a predetermined measurement point of the drive mechanism in a computer used as an analysis determination unit of a vehicle seat drive mechanism inspection device that determines the quality of the vehicle seat drive mechanism. The detection signal detected by the vibration sensor is analyzed to determine the presence or absence of abnormal noise, and an analysis determination procedure is performed to determine the quality of the drive mechanism based on the presence or absence of this abnormal noise.

  In the analysis determination procedure, it is preferable that the detection signal obtained from the vibration sensor is frequency-analyzed and the presence or absence of the abnormal noise is determined based on the presence or absence of irregular vibration. The analysis determination procedure preferably determines the presence or absence of the irregular vibration by comparing power spectra of harmonic components of the fundamental frequency in the frequency analysis result. In the analysis determination procedure, it is preferable that the presence or absence of the irregular vibration is determined in consideration of the presence or absence of a predetermined characteristic frequency component in the frequency analysis result. The drive mechanism can be suitably used for quality determination of a power unit of an electric power seat.

  In the present invention, a vibration sensor is attached to a predetermined measurement point of a vehicle seat drive mechanism, particularly a power unit of an electric power seat, and the presence or absence of abnormal noise is determined by analyzing the vibration waveform of the vibration sensor. Preferably, the configuration is such that frequency analysis of a vibration waveform that is a detection signal is performed to determine whether or not irregular vibrations are superimposed, thereby detecting the presence or absence of abnormal noise. For this reason, in the technology for inspecting the quality of a drive mechanism such as a power unit of an electric power seat using the presence or absence of abnormal noise, it is possible to make a determination more accurately and easily than before without a soundproof environment.

FIG. 1 is a diagram showing a schematic configuration of a drive mechanism inspection apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing a slider mechanism of the electric power seat that is an inspection object used in the example. FIG. 3 is a diagram illustrating measurement points of vibration measurement in the example. FIG. 4A is a diagram showing the results of the sensory evaluation of the operating sound of the power unit, and FIG. 4B is a diagram showing the sound pressure characteristics when the power unit is moving forward and backward. 5A and 5B are diagrams showing an original waveform of vibration measurement at the measurement point G, where FIG. 5A is an original waveform when traveling backward (F → R), and FIG. 5B is an original waveform when traveling forward (R → F). FIG. FIG. 6 shows No. 1 measured at the measurement point G. 1 (OK product) and No. 1 2 (NG product) is a diagram showing the FFT analysis, (a) is the reverse (F → R), (b) is the forward (R → F) analysis results It is. FIG. 7A shows the power unit no. 1 (OK product) and No. 1 2 (NG product) is a diagram showing a time axis waveform of the sound pressure at the time of forward movement, and FIG. 1 (OK product) and No. 1 It is the figure which showed the 1/3 octave band frequency analysis characteristic of the sound pressure fluctuation at the time of advance of 2 (NG product). 8 shows power unit No. 2 at 2 to 5 kHz. 1, no. 2, no. 3, no. 6A and 6B are diagrams showing frequency analysis characteristics of sound pressure fluctuations during forward / reverse travel, where FIG. 6A shows the forward travel time and FIG. 6B shows the reverse travel time. FIG. 9 shows the power unit no. 1, no. 2, no. 3, no. 6 is a graph showing the slope when a logarithmic graph of power spectrum-frequency is drawn from the frequency characteristics of sound pressure fluctuation during forward / reverse travel of FIG. 6, (a) is the forward travel time, (b) is the reverse travel time. FIG. FIG. 10 is a diagram illustrating frequency analysis results of an OK product and an NG product in Experimental Example 2. FIG. 11 is a diagram illustrating an example in which a reference line serving as a determination criterion for OK products and NG products is provided in Experimental Example 2. FIG. 12 is a diagram showing the main part of the structure of the power unit used in Experimental Example 3. 13A and 13B are diagrams showing the frequency analysis results of Experimental Example 3. FIG.

  Hereinafter, the present invention will be described in more detail based on the embodiments of the present invention shown in the drawings. As shown in FIG. 1, the vehicle seat drive mechanism inspection apparatus 1 according to this embodiment includes a vibration sensor 2 and an analysis determination unit 3.

  The vibration sensor 2 is used by attaching them to arbitrary measurement points of the drive mechanism of the vehicle seat to be inspected. The vehicle seat drive mechanism here includes various components that constitute a slider mechanism, a lifter mechanism, a reclining mechanism, and the like. These are positioned as power units in an electric power seat that is operated electrically.

  The analysis determination unit 3 includes a computer, and analysis determination processing is executed by an analysis determination procedure as a computer program. Specifically, the detection signal detected by the vibration sensor 2 when the drive mechanism (power unit) is driven is analyzed to determine the presence or absence of abnormal noise, and the quality of the drive mechanism is determined based on the presence or absence of this abnormal noise. .

  The analysis determination unit 3 performs frequency analysis on the vibration waveform that is the detection signal of the vibration sensor 2, thereby detecting the presence or absence of irregular vibration, and when the irregular vibration occurs, “abnormal noise”, that is, “ If it is determined as “defective product” and no irregular vibration occurs, it is determined as “no abnormal noise”, that is, “good product”. The determination result is output to a monitor or the like.

(Experimental example 1)
(Determination of non-defective / defective products by vibration measurement)
(experimental method)
An experiment was conducted with the power unit 10 constituting the slider mechanism of the electric power seat shown in FIG. This power unit 10 has a structure having a pair of left and right slide adjusters 11 and 11 and a slide plate 12 for connecting them. The external dimensions are width: 490 mm, length: 500 mm, and the stroke in the front-rear direction is 260 mm. It is. In addition, drive system components such as a motor 13 are arranged on the slide plate 12. That is, a motor (DC ferrite, rated voltage: 12 V, no-load rotation speed 3600 ± 500 rpm, rated load rotation speed (load: 9.8 ± 0.9 N · cm): 2850 ± 600 rpm) near one end in the longitudinal direction 13 is arranged, and the rotation of the motor 13 is transmitted to the left and right slide adjusters 11 and 11 via the cable 14 and the transmission 15. The cable 14 has a double structure of an outer cable and an inner cable made of a stranded wire. The cable 14 is fixed to the slide plate 12 via a locking member 14a.

  The test was performed in two directions: when the slide plate 12 was moved from the front end to the rear end in the longitudinal direction of the slide adjusters 11 and 11 (reverse movement) and when operated from the rear end to the front end (forward movement). As a vibration sensor, a piezoelectric acceleration pickup (PV-85 manufactured by Rion) was attached to 10 points A to J of the slide plate shown in FIG. At the same time, sound pressure was measured with a sound level meter (NL-14 manufactured by Lion). Further, the unit was reciprocated 10 times, and heat generation due to sliding resistance was examined with a thermotracer (NEC Sanei TH7102MX).

  The power unit 10 to be inspected is a total of 8 units (No. 1) of 6 products (non-defective product (OK product)) recognized as normal by sensory evaluation and 2 products (non-defective product (NG product)) recognized as abnormal noise. To No. 8). The sensory evaluation is performed in a dark noise environment of about 40 dB (A), and the power unit operation sound sensory evaluation is “very good” (1 point), “good” (2 points), “slightly good” (3 points) ), “Slightly bad” (4 points), “Bad” (5 points), “Very bad” (6 points) are evaluated in 6 levels, 1 to 3 are defined as pleasant sounds, and 4 to 6 points are defined as unpleasant sounds. did.

  FIG. 4A shows the result of scoring by sensory evaluation of the power unit operating sound. Of the eight power units (No. 1 to 8), six (No. 1, 3, 4, 5, 7, 8) were rated as “quiet sounds” and were rated as “unpleasant sounds”. There were two power units (No. 2, 6). The breakdown of the average values of forward and reverse was 1 point: 3 units, 2.5 points: 1 unit, 3 points: 2 units, 5 points: 1 unit, 6 points: 1 unit. FIG. 4B shows the sound pressure characteristics when the power unit is moving forward and backward. The sound pressure characteristic of the power unit evaluated as “quiet” by the sensory evaluation was 51 to 55 dB (A), and the sound pressure characteristic of the power unit evaluated as “unpleasant sound” was 61 to 72 dB (A). When the sound pressure characteristic is 55 dB (A) or more, there is a high possibility that the user feels “uncomfortable sound”.

(Experimental result)
As a result of measuring the vibration at each of the measurement points A to J and performing the FFT analysis, it was confirmed that the vibration of 200 to 400 Hz appears remarkably in the vicinity of the inner cable (points A, E, and G). Further, comparing the unit temperatures, it was found that the NG product generated heat locally in the cable. No. determined as an OK product. 1 and No. determined as an NG product. Comparison of the original waveforms measured at point G is shown in FIG. 5A (front → rear (F → R)) and FIG. 5B (rear → front (R → F)). In all cases, there was no clear difference in the amplitude of vibration, and it was not possible to judge whether the amplitude was large or small.

  Since a high vibration spectrum of 200 to 400 Hz appeared in the vicinity of the point where the cable was hot, the vibration at the point G was compared. 6 (a) and 6 (b) are Nos. Measured at point G. 1 and No. The vibrations before and after 2 and after and before are compared by FFT analysis. In the NG product, various irregular vibrations were superimposed on the fundamental frequency, and a peak of the vibration spectrum was observed at 300 to 400 Hz. The vibration of 100 to 300 Hz is considered to be generated by contact due to the relative movement of the inner cable and the outer cable. Images of the movement of the inner cable are shown in FIGS. 6 (a) and 6 (b). Considering the reduction ratio of the worm gear, the vibration around 400 Hz is considered to be caused by the rattling noise between the gears. Irregular whirling motion occurs in the inner cable, and the resulting vibration is transmitted to the gear and motor, resulting in misalignment and abnormal noise. Therefore, it is considered that the main cause of the noise of the power unit is vibration generated by the inner cable. From the above, it can be seen that abnormal noise can be evaluated by the difference in vibration spectrum at 300 to 400 Hz.

  In addition, other power unit No. recognized as NG product by sensory evaluation. 6. Similar results were obtained for other 5 power unit products that were recognized as OK products. In No. 6, superposition of irregular vibrations was detected, and it was possible to identify that abnormal noise was generated.

(Verification by sound pressure measurement)
Simultaneously with the vibration measurement described above, a sound level meter (NL-14 NL-14) was installed at a position 450 mm above the center of the slide plate to measure the sound pressure. FIG. 7A shows the power unit no. 1 (OK product) and No. 1 2 shows a time-axis waveform of sound pressure during forward movement of 2 (NG product). The power unit No. evaluated as “quiet” by sensory evaluation. Compared with No. 1, the power unit No. evaluated as “uncomfortable noise”. The waveform of No. 2 has a large amplitude, and in this time-axis waveform, a clear difference can be confirmed between the power unit evaluated as “quiet sound” and the power unit evaluated as “unpleasant sound”.

  FIG. 7B shows the power unit no. 1 (OK product) and No. 1 2 (NG product) shows a 1/3 octave band frequency analysis characteristic of sound pressure fluctuation during forward movement. The power unit No. evaluated as “quiet” by sensory evaluation. Power unit No. 1 evaluated as “uncomfortable sound” in sensory evaluation as compared with No. 1. The 1/3 octave band frequency analysis characteristic of 2 has a particularly high sound pressure of 2 to 5 kHz, and it can be estimated that unpleasant noise is generated from the components of the drive system in this frequency band.

  FIGS. 8A and 8B show frequency analysis characteristics of sound pressure fluctuations when the power unit is moving forward and backward at 2 to 5 kHz. However, in FIGS. 8A and 8B, the frequency analysis characteristics of all power units are complicated and difficult to see. 2 and no. Other than 6 NG products, No. 6 out of 6 OK products. 1 and no. Only characteristic 3 is shown. The remaining four OK products (No. 4, No. 5, No. 7 and No. 8) are also No. 1 and no. 3 shows the same tendency. 8A and 8B, the power unit No. evaluated as “uncomfortable sound” by sensory evaluation. 2 and no. The power spectrum of No. 6 was evaluated as “No. 1 and no. The power spectrum is higher than that of No. 3, and a clear superior difference can be confirmed.

Next, since the sensitivity to human sound is almost proportional to the logarithm of sound pressure (Pa), abnormal noise was determined from a logarithmic graph of power spectrum-frequency. FIGS. 9A and 9B show slopes when a logarithmic graph of power spectrum-frequency is drawn from the frequency characteristics of sound pressure fluctuations when the power unit moves forward and backward. However, for the same reason as FIG. 2 and no. Other than 6 NG products, No. 6 out of 6 OK products. 1 and no. Only characteristic 3 is shown.
The inclination of the power unit evaluated as “quiet” in the sensory evaluation was “−0.08 to −1.29” when traveling forward, and “−0.36 to −1.03” when traveling backward (note that This range of inclination shows the minimum and maximum values of 6 OK products). On the other hand, No. evaluated as “unpleasant sound”. 2 and no. The inclination of 2 to 5 kHz of the two power units of 6 was “−1.49 to −1.75” when moving forward, and “−1.34 to −1.90” when moving backward. When considering both forward and reverse travel, the OK value of 6 OK products rated as “quiet” was the maximum value of “−1.29”, and 2 out of NG products rated as “uncomfortable sound”. The minimum value of the inclination is “−1.34”, and a criterion for distinguishing between an OK product and an NG product can be set near “−1.30” therebetween. From this, a logarithmic graph of frequency analysis characteristics when the power unit is activated is drawn, and between the inclination of 2 to 5 kHz which is a frequency band where it can be estimated that unpleasant noise is generated from the drive system parts, and sensory evaluation It can be seen that there is a correlation, and this makes it possible to determine whether or not abnormal noise has occurred.

  From the above, the power unit No. in which irregular vibration is detected by the vibration measurement of the present invention. 2, no. No. 6 is a power unit No. 6 that was determined to correspond to “uncomfortable sound” of sensory evaluation in sound pressure measurement, and no irregular vibration was detected. 1, no. 3-5, no. 7, no. In the sound pressure measurement, 8 is determined to be equivalent to “quiet sound” of sensory evaluation. Thereby, it is understood that it is effective to evaluate abnormal noise by vibration measurement according to the present invention, and to determine whether the product is good (OK product) or defective (NG product) based on the presence or absence of abnormal noise evaluation.

(Experimental example 2)
(experimental method)
60 power units 10 constituting the slider mechanism of the electric power seat are prepared, and a piezoelectric acceleration pickup (Rion PV-) which is a vibration sensor is provided at a point B (back surface) in FIG. 85), and when the slide plate 12 is operated from the front end to the rear end in the longitudinal direction of the slide adjusters 11 and 11 (reverse) and from the rear end to the front end in the same manner as in Experimental Example 1. Vibration was measured in two directions (forward). At the same time, a sound level meter (NL-14 manufactured by Lion) was installed at a height of about 40 cm, and sound pressure was measured in a background noise environment of about 40 dB. The specifications of the motor 13 attached to each power unit 10 were the same as those in Experimental Example 1. The natural frequency of the slide plate 12 was about 750 Hz. In addition, the 60 power units 10 compiled the data by distinguishing between a non-defective product (OK product) recognized as normal and a defective product (NG product) recognized as abnormal noise by the same sensory evaluation as in Experimental Example 1. .

(Experimental result)
Frequency analysis (FFT analysis) was performed based on the vibration sensor data recorded by performing full stroke operation for each of the forward and backward movements (FFT analysis conditions: sampling frequency: 5000 Hz, analysis data length: 8192, window function: Hanning window, average Processing: addition average, overlap amount 90%).

FIG. 10 shows the FFT analysis results of representative cases of OK and NG products. In both the OK product and the NG product, a first order peak is recognized in the vicinity of 90 Hz, and as indicated by a circle, harmonic components such as second order and third order components are generated. However, as for the peak value of the power spectrum of each frequency component, the value of the NG product far exceeds the value of the OK product. In addition to this, as shown by the black triangle mark, the NG product has a peculiar peak in the vicinity of 140 Hz that is not recognized in the OK product, and a high-intensity spectrum is generated in the secondary and tertiary components. doing. There is also a unique frequency component as indicated by a square mark in the vicinity of 320 Hz.
Therefore, it can be seen that various irregular vibrations are superimposed on the fundamental frequency in the NG product. This is considered to be due to a plurality of factors such as a speed change that occurs during the full stroke operation of the slide plate 12 and irregular vibration of the cable. Moreover, it is thought that the vibration near 140 Hz seen only in the NG product is the starting point of abnormal noise. From these facts, it can be said that it is appropriate to determine the presence or absence of abnormal noise based on the presence or absence of irregular vibration.

  Next, in order to quantify abnormal noise, the power spectra of the OK product unit group and the NG product unit group were compared, and a reference line for distinguishing between them was set on the graph shown in FIG. This reference line is such that most of the peak of the power spectrum in the OK product (for example, 60% or more of the peak of the OK product in a predetermined frequency band as shown in FIG. 11) is below this position, or in the OK product. It is set so that all the peaks of the power spectrum are in positions below this. In FIG. 11, the reference line is set in the frequency band of 250 to 500 Hz. In this frequency band, both the 140 Hz harmonic component unique to the NG product and the 90 Hz harmonic component common to the OK product are both present. This is because various frequency components are likely to appear, such as appearing at a predetermined intensity, and a specific frequency component in the vicinity of 320 Hz, making it easy to distinguish between OK and NG products. Of course, 250 to 500 Hz is an example, and for example, determination may be made including a frequency band of about 100 Hz before and after that. A reference line was set in such a region, and when the area of the part surrounded by the line of the power spectrum drawn in a range exceeding the reference line was obtained, between the size of the area and sensory evaluation of abnormal noise, Correlation was obtained. Therefore, the presence or absence of abnormal noise can be determined based on the size of the area surrounded by the power spectrum line in a range exceeding the reference line. The area is not limited to the range exceeding the reference line, and for example, the area corresponding to the minimum value of the power spectrum can be drawn and the area can be obtained using the line as a reference.

  As described above, the analysis determination unit 3 that executes the analysis determination procedure uses the power spectrum of the harmonic component of the fundamental frequency in the frequency number analysis result of the vibration waveform that is the detection signal of the vibration sensor 2 (basic common to OK and NG products). The presence of irregular vibrations by comparing the frequency components and the harmonic components of the frequency component specific to the NG product), that is, the frequency of the power spectrum exceeding the reference line (for example, as described above) It is preferable to determine that there is irregular vibration when the (determined by area) is greater than or equal to a predetermined value. In addition, in the frequency analysis result, the presence or absence of a predetermined characteristic fundamental frequency component is also considered, for example, if the existence of a 140 Hz frequency component peculiar to the NG product is confirmed as described above. It is preferable to make a judgment.

(Experimental example 3)
In Experimental Example 1 and Experimental Example 2, a cable 14 for transmitting the rotation of the motor 13 is stretched over the slide plate 12 spanned between the pair of left and right slide adjusters 11, 11. For this reason, the cable 14 is likely to generate irregular vibrations as described above.

  On the other hand, in the power unit 100 constituting the slide mechanism shown in FIG. 12, a rack 210 is attached to the lower rail 111 of the slide adjuster 110 on one side, and a pinion 220 that meshes with the rack 210 is pivotally supported by the upper rail 112, and the pinion 220 is It is rotated by the motor 130. A slide adjuster 110 (not shown in FIG. 12) opposite to the slide adjuster 110 provided with the rack 210 is connected by a connecting shaft 230, and the pinion 220 is engaged with the rack 210 and rotated by the rotation of the motor 130. The upper rail 112 moves back and forth by one-side drive. Therefore, a cable that tends to be a source of irregular vibration is not provided between the pair of left and right slide adjusters 110, 110.

  Therefore, in such a power unit 100, the same vibration sensor as that in the above-mentioned experimental example is attached to the bracket 150 on which the pinion 220 is supported, the full-stroke drive is performed in the front and rear directions, the vibration is measured, and it is verified whether the presence or absence of abnormal noise can be determined. . The result is shown in FIG.

  In FIG. 13, “threshold value” is obtained by comparing the power spectra of the OK product and the NG product of Experimental Example 2 and drawing the power spectrum that becomes the boundary between the OK product and the NG product. As is clear from FIG. 13, the power unit of Experimental Example 3 is below the “threshold value” both in the forward direction (FIG. 13A) and in the reverse direction (FIG. 13B), and irregular vibrations up and down are observed. It does not occur, and it can be seen that the occurrence of abnormal noise is extremely low. Therefore, the method for determining the occurrence of abnormal noise using the vibration sensor of the present invention is not limited to the power unit having a cable that easily generates irregular vibration as in Experimental Example 1 and Experimental Example 2, but as in Experimental Example 3. The present invention can be applied to noise detection of various types of drive mechanisms including power units that do not include a cable.

DESCRIPTION OF SYMBOLS 1 Drive mechanism inspection apparatus 2 Vibration sensor 3 Analysis determination part

Claims (3)

A vehicle seat drive mechanism inspection method for determining the quality of a vehicle seat drive mechanism,
The drive mechanism to be inspected includes a pair of left and right slide adjusters, a slide plate connecting the pair of left and right slide adjusters, a motor supported by the slide plate, and rotation of the motor to the pair of left and right slide adjusters. A power unit that is supported by the slide plate and has a double structure of an outer cable and an inner cable for transmission via a mission, and constitutes a slider mechanism of the vehicle seat ,
A vibration sensor is attached to the slide plate,
A frequency analysis is performed on a detection signal detected from the vibration sensor when the power unit is driven, the presence or absence of irregular vibration is determined from the result of the frequency analysis, and the presence or absence of abnormal noise is determined based on the presence or absence of the irregular vibration. A method for inspecting a vehicle seat drive mechanism, wherein the quality of the power unit is determined . The vehicle seat drive mechanism inspection method according to claim 1 , wherein the presence or absence of the irregular vibration is determined by comparing power spectra of harmonic components of a fundamental frequency . The vehicle seat drive mechanism inspection method according to claim 2 , wherein the presence or absence of the irregular vibration is determined in consideration of the presence or absence of a predetermined characteristic frequency component .