JP2540915B2 - Engine abnormal noise detection method - Google Patents

Description

The present invention relates to a method for detecting abnormal noise of an engine, and more particularly to an engine capable of quantitatively detecting an abnormal vibration level of the engine in a vehicle production process. An abnormal sound detection method.

[Prior Art] Conventionally, abnormal noise detection in an engine production process has been performed by so-called sensory evaluation in which a worker directly hears a vibration sound. However, this sensory evaluation had problems such as variation depending on the mood of the worker on the day, difficulty in hearing abnormal noise due to the influence of other noise at the work site, and difficulty in identifying the abnormal portion. .

Therefore, for example, Japanese Utility Model Application Laid-Open No. 57-126537 proposes a device for detecting engine misfire at a sound pressure level. In this conventional technique, the engine sound is collected by a microphone and electrically A technique is disclosed in which a signal is converted into a signal, the signal level is compared with a reference value, and if the signal level is equal to or higher than the reference value, a misfire signal is output to issue an alarm.

[Problems to be Solved by the Invention] However, the above-described conventional abnormal sound detection device simply compares a preset normal sound of the engine and an abnormal sound at the time of misfire by frequency-sound pressure level (dB). However, it was difficult to identify the place where the abnormal noise occurred and to quantitatively grasp the abnormal noise level.

The present invention has been made in view of the above problems, and provides an abnormal noise detection method for an engine capable of quantitatively detecting the abnormal vibration level of the engine and accurately grasping the occurrence site thereof. Has an aim.

Structure of the Invention [Means for Solving the Problems] In order to achieve the above object, the present invention has the following structures as means for solving the problems. That is,
As shown in the flow chart of FIG. 1, the engine noise detection method of the present invention electrically detects the vibration state of the engine, and takes in the vibration waveform and the timing pulse synchronized therewith (P
1) An abnormal noise detection method for an engine, which detects an abnormal vibration level of an engine and a site where the abnormal vibration is generated, wherein the vibration waveform is divided into a plurality of regions for each cycle of the timing pulse, and each of the regions is divided. Step of searching for the maximum deviation of the vibration waveform at P and storing the area name and the value of the deviation when the deviation is larger than a predetermined level (P2)
And, based on the area name and the deviation value stored for each cycle of the timing pulse, calculating an average value of deviation values for each area within a plurality of cycles of the timing pulse (P3) And a step (P4) of detecting an abnormal vibration level of the engine and a site where the abnormal vibration is generated from the region name and the calculated average value.

[Operation] According to the engine abnormal noise detection method of the present invention configured as described above, the vibration waveform of the engine and the timing pulse synchronized therewith are captured (P1), and the vibration waveform is obtained for each cycle of the timing pulse. Divide into multiple areas, search for the maximum deviation of the vibration waveform in each area, and when the deviation is larger than a predetermined level, the area name and the deviation value are stored (P2), and one cycle of the timing pulse Based on the area name and the deviation value stored for each, calculate the average value of the deviation value for each area in the plurality of cycles of the timing pulse (P3), the area name and the calculated average It works to detect the abnormal vibration level of the engine and the location of the abnormal vibration from the value (P4).

By the way, it has been clarified from the mechanism that the abnormal noise of the engine is always generated at a constant timing and is generated with two crank rotations as one cycle. Therefore, for example, an ignition pulse signal from a distributor is used as a timing pulse for the engine. Captured with the vibration waveform of
The vibration waveform is observed in synchronization with this timing pulse. Also, it has been clarified that the engine noise is generated differently even within the same cycle depending on the location where the engine noise is generated.Therefore, the vibration waveform is divided into multiple regions for each cycle of the timing pulse. However, the abnormal vibration level of the engine and the location where the abnormal vibration occurs can be detected by calculating the average value of the deviation values for each region within the plurality of cycles of the timing pulse with the above-described configuration. it can.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a schematic configuration diagram of an abnormal sound detection system that employs an abnormal sound detection method for an engine according to an embodiment of the present invention.

In the figure, the explosion process of the engine 10 is synchronized with the ignition pulse from the distributor 12, an ignition signal is generated in synchronization with the process, and each cylinder is driven in order by controlling the ignition signal. The vibration acceleration of the engine 10 caused by the explosion at this time is a plurality of vibration detection pickups 16-1 attached to a predetermined part of the engine,
The parts to be inspected are shared by providing a plurality of pickups 16 in this way. The vibration detection signal detected by the pickup 16 is a bandpass filter 20-1, in which a desired frequency band (a frequency band in which abnormal noise of the engine is generated) is set in advance with the amplifiers 18-1, 18-2 ,. Are input to the microcomputer 22 via 20-2 ,. At the same time, the ignition signal from the distributor 12 is also input to the microcomputer 22.

The microcomputer 22 is composed of an electronic control device 24 as a main body, a keyboard 26 as a peripheral device thereof, a CRT display 28, and a flexible disk drive 30 as a data store device.

The electronic control unit 24 includes a well-known CPU 24a, ROM 24b, RAM 2
4c, an input port 24d, an input / output port 24e, etc., and the vibration waveform signal from the band pass filter 20 and the ignition signal from the distributor 12 are input to the input port 24d. A keyboard 26, a CRT display 28 and a flexible disk drive 30 are connected to the input / output port 24e. Such an electronic control unit 24 takes in the vibration waveform and the ignition signal, detects the abnormal vibration level of the engine 10 and the site where the abnormal vibration occurs, displays the detection result on the CRT display 28, and also the flexible disk drive 30. The abnormal sound detection processing to be stored in is executed.

An abnormal sound detection routine that is executed by the electronic control unit 24 and shows the above-described processing according to the present invention will be described below with reference to the flowchart of FIG.

When the processing is started, first, the processing moves to step 100, and the number of times of measurement m of the vibration cycle is set to a value 1 as an initial setting. In the following step 110, the vibration waveform signal output from the vibration detection pickup 16 and input via the amplifier 18 and the bandpass filter 20 and the distributor 12 are input.
Ignition signals input from are respectively captured. In the following step 120, the ignition pulse of one cylinder having the captured ignition signal is triggered to extract the vibration waveform signal in the period until the next ignition pulse, and the extracted vibration waveform signal is output to a plurality of gates. Divide by. That is,
As shown in FIG. 4, a vibration waveform signal for one cycle of an ignition pulse of a certain cylinder is divided into, for example, four gates 1, 2, 3, and 4. It should be noted that the timing of this division is set to a timing obtained in advance by an experiment so that the location of the abnormal noise of the engine 10 can be specified.

In the following step 130, the peak + peak value (peak to peak valu) is calculated for each of the divided gates 1, gates 2, ...
The step e) is performed, and in the subsequent step 140, it is determined whether or not there is a gate 1, a gate 2, ... In which the searched peak + peak value exceeds a predetermined slice level. Here, if an affirmative decision is made, the processing moves to step 150,
The gate number and peak / peak value are stored in RAM 24c. That is, in the case shown in FIG. 4, the gate 1 and the gate 2 are selected in both cycles of the ignition signal, and the gate N
o. and peak + peak value will be stored for each cycle. On the other hand, if a negative decision is made in step 140, the process of step 150 is skipped and the process proceeds to the subsequent step.

Note that the peak + peak value of the vibration waveform signal generally varies with the cycle of the ignition signal, so in order to obtain the average value in a plurality of cycles, in the subsequent step 160, the number m of times of measurement of the vibration cycle has reached a preset M times. If it is determined that the number of times of measurement m has not reached M times, the process proceeds to step 170, where the number of times of measurement m is incremented by the value 1, and the vibration waveform signal of the next cycle is added. The processing of steps 110 to 160 is repeated.

If it is determined in step 160 that the number of measurements m has reached M times, the process proceeds to step 180, and the process of averaging the peak + peak values stored in these M times of processes is performed for each gate. To do. After performing the averaging process in this way, the process proceeds to step 190, where the level of the abnormal vibration of the engine 10 is known from the averaged peak + peak value and the corresponding gate No. Identify the abnormal vibration level and the location of the abnormal vibration on the CRT.
Display on the display 28. In the following step 200, data indicating the abnormal vibration level and the site where the abnormal vibration is generated is stored in the flexible disk drive 30. After executing step 200, the process of this routine ends.

In the abnormal noise detection routine, only the processing of the signal obtained from one vibration detection pickup 16 is shown, but the same processing is performed on the signals obtained from the other vibration detection pickups.

As described above, according to the embodiment of the present invention, it is possible to quantitatively detect the abnormal vibration level of the engine 10 and to accurately grasp the occurrence site.

Also, because the data is quantitatively stocked,
Even if a process complaint occurs after the abnormal noise inspection, it is possible to quickly find the cause of abnormal vibration. Furthermore, by checking these abnormal data, it is possible to estimate the cause of a defect such as a mounting error in the previous process, a mounting error, or a processing defect, and there is an advantage that an error countermeasure can be swiftly performed.

In addition, since the abnormal vibration level of the engine currently being produced can be obtained numerically, it is easy to confirm the effect when the engine design is changed, and it is effectively used as data when the engine design is changed. can do.

In the above embodiment, the case where the acceleration vibration pickup 16 is used to obtain the vibration waveform of the engine 10 has been described, but in addition to this, for example, a microphone is used to catch the vibration sound, and the same processing as described above is performed. It may be a method of performing.

Further, in the above-mentioned embodiment, the maximum deviation of the vibration waveform searched in the step P2 is the maximum deviation of the peak + peak value, which is the sum of the deviation on the positive side and the deviation on the negative side. Alternatively, it may be configured to search for the maximum value that is the deviation on the positive side, or may be configured to search for the minimum value that is the deviation on the negative side, as in the above embodiment. Has a great effect.

EFFECTS OF THE INVENTION As described above in detail, the abnormal noise detection method for an engine according to the present invention can quantitatively detect an abnormal vibration level of the engine and accurately grasp the location where the abnormal vibration occurs.

[Brief description of drawings]

FIG. 1 is a flow chart showing the basic configuration of the present invention, FIG. 2 is a schematic configuration diagram of an abnormal sound detection system adopting an abnormal sound detection method for an engine which is an embodiment, and FIG. 3 is its electronic control unit. FIG. 4 is a flowchart showing an abnormal noise detection routine executed, and FIG. 4 is an explanatory diagram used for explaining the abnormal noise detection routine. 10 …… Engine 12 …… Distributor 16 …… Vibration detection pickup 22 …… Microcomputer 24 …… Electronic control unit

Claims (1)

(57) [Claims] 1. A different engine for electrically detecting a vibration state of an engine and capturing a vibration waveform thereof and a timing pulse synchronized therewith to detect an abnormal vibration level of the engine and a portion where the abnormal vibration occurs. A sound detection method, wherein the vibration waveform is divided into a plurality of regions for each cycle of the timing pulse, the maximum deviation of the vibration waveform in each region is searched, and the region is detected when the deviation is larger than a predetermined level. A step of storing the name and the value of the deviation thereof, based on the area name and the value of the deviation stored for each cycle of the timing pulse, the deviation of each area within the plurality of cycles of the timing pulse A step of calculating an average value of the values, and a step of detecting an abnormal vibration level of the engine and a part where the abnormal vibration is generated from the area name and the calculated average value. And a method for detecting abnormal noise in an engine.