JPH04242138A - Engine inspecting apparatus - Google Patents

Abstract

PURPOSE:To provide an engine inspecting apparatus which captures the sound of an engine to be sent to an assembly line in a total mode and judges the good or bad of the engine. CONSTITUTION:This apparatus is composed of a microphone 4, a tachometer 3 and a quality detecting device 5. The microphone 4 is provided in the vicinity of an engine 2 to be measured and detects the sound of the engine 2. The tachometer 3 detects the number of rotation of the engine 2. The quality detecting device 5 receives the detected engine-sound signal from the microphone 4 and the detected number-of-rotation signal from the tachometer 3 and detects the quality of the vibration of the engine based on judging references. The detected engine-sound signal of the microphone 4 and the detected number-of- rotation signal of the tachometer 3 are inputted, and the quality of the engine sound can be judged based on judging references. Therefore, the variation of the quality of the engine 2 can be eliminated, the shortage of skilled workers can be covered and the workers can be released from the adverse environment when the engine 2 is operated.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to equipment for determining the quality of an engine used when performing performance tests on an engine before it is assembled into a vehicle body in the vehicle production process, and particularly to equipment for determining the quality of engine sound. It is.

0002

[Prior Art] Conventionally, when performing a performance test on an engine before it is installed in the vehicle body, the engine sound is evaluated.
Workers directly listen to the engine sound and evaluate its quality.
This was done through so-called sensory evaluation. However, this type of sensory evaluation has the problem of variations in engine quality due to individual differences, and the problem of engine quality deteriorating due to a lack of skilled workers.
For example, as disclosed in Japanese Unexamined Patent Publication No. 61-234332, engine sound is frequency-analyzed, separated into signals in each frequency band, and based on each separated signal, the presence or absence of an abnormal sound is determined. The type is being determined.

0003

[Problems to be Solved by the Invention] However, with the above-mentioned conventional method for detecting an abnormality in engine noise, even if the part where the abnormal sound is generated is detected, it is not possible to determine the degree of abnormality in the engine as a whole. There was a problem in that it was difficult to judge the quality of the product.

[0004] The present invention solves the above problems,
The object of the present invention is to provide engine quality determination equipment that can comprehensively capture abnormal sounds from engines sent to an assembly line and determine whether the noise is good or bad.

[0005]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the engine quality determination equipment of the present invention includes a microphone installed near the engine to be measured and for detecting engine sound;
A tachometer that detects the rotation speed of the engine to be measured; and a quality detection device that receives an engine sound detection signal from the microphone and a rotation speed detection signal from the tachometer and detects whether the engine sound is good or bad based on a determination criterion. It is characterized by the fact that it is equipped with

[0006]

[Operation] With the above configuration, the engine sound detection signal of the microphone and the rotation speed detection signal of the tachometer are input, and for example, under the condition of constant rotation speed, the frequency is analyzed and engine sound exceeding the threshold is detected. The quality of the engine sound is determined based on weights and criteria.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of an engine quality determination facility according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 is a test bench for an engine 2, and the electrical system and fuel system are connected to the engine 2 placed on the test bench 1, and the engine 2 is started. At this time, a computer (not shown) on the test bench 1 controls the rotational speed of the engine 2, the appropriate value of the fuel supply amount for this rotational speed, etc., and the performance test of the engine 2 is performed.

Further, in FIG. 1, numeral 3 is a tachometer installed on the test bench 1 to count the ignition pulses of the engine 2, and 4 is a microphone installed near the engine 2 to detect the sound of the engine 2. The rotational speed detection signal of 3 and the engine sound detection signal of the microphone 4 are sent to a quality determination device 5 with a built-in microcomputer installed separately.
is input.

As shown in FIG. 2, the quality determination device 5 converts the input rotation speed detection signal into an AD (analog-digital) signal.
AD conversion means 6 to convert, rotation speed judgment means 7 to judge whether the digital rotation speed data inputted from the AD conversion means 6 is constant, and when a rotation speed constant signal is inputted from the rotation speed judgment means 7, the input engine A frequency analysis means 8 that analyzes the frequency of a sound detection signal, converts the result into a digital value, and outputs it, and digital engine sound analysis data output from the frequency analysis means 8 are set as shown in FIG.
The normality determined by experiment for each rotation speed is stored in advance by n storage means 9 (n is a positive integer) stored for each frequency band and digital rotation speed data input from the AD conversion means 6. n threshold setting means 10 for searching and setting the center value L and threshold values rU (upper limit) and rL (lower limit) for each frequency band in the above-mentioned state; The n abnormal value setting means 11 sets frequency distribution data in an abnormal state due to the cause, and the digital engine sound data stored in the storage means 9 is sequentially recalled for each frequency band, and this digital engine sound data is When the threshold value rU, rL set by the threshold value setting means 10 is exceeded, a threshold value over signal is output, and the degree of the threshold value is determined by the distance (sound strength) s of the maximum value from the center value L. n first evaluation means 12 that evaluate in the range of 0 to 1 (evaluation values a1 to an)
When a threshold over-threshold signal is input from the first evaluation means 12 for each frequency band, the digital engine sound data stored in the storage means 9 is sequentially recalled, and this digital engine sound data and the abnormal value setting means 11 For example, as shown in FIG. 4, the degree of similarity with the abnormal frequency distribution data set in Input the evaluation means 13 (evaluation values b1 to bn) and the evaluation values a1 to an of each first evaluation means 12, multiply them by their respective weights α1 to αn, add them, and evaluate them in the range of 0 to 1. and its evaluation value c(=a1 *α1 +a2
*α2 +...+an *αn), and displays the determination results of the determination means 14 and the evaluation values b1 to bn of the second evaluation means 13;
It is comprised of a display means 15 made of, for example, a liquid crystal display device.

The operation of determining the quality of the engine 2 by the quality determining device 5 having the above configuration will be explained below. Step-1: The rotation speed determination means 7 determines the condition that the rotation speed detection signal is constant at a predetermined rotation speed. Step-2 The frequency analysis means 8 performs frequency analysis of the engine sound from the engine sound detection signal. Step-3 Weight α1 for each of n bands determined by a specific frequency
~αn is set. Step-4 The strength (decibel) of the sound at frequencies outside the frequency distribution specified by the first evaluation means 12 is determined by the distance (sound strength) s of the maximum value from the center value L, as shown in FIG. Each band is evaluated to an evaluation value of 0 to 1 (a1 to an). Step-5 The determining means 14 determines that a1 *α1 +a2 *α2
+...+an *αn is calculated and determined in the range of 0 to 1 to determine the overall quality of the engine sound. Step-6 When an abnormal sound occurs in a specific band, the second evaluation means determines whether it matches or is similar to the frequency distribution of the abnormality identified in that band, as shown in Figure 4. Evaluate in the range of 0 to 1 depending on the distance u between value data (
Evaluation values b1 to bn). Therefore, for each cause of abnormality, for example, cause A is evaluated in the range of 0 to 1. Step-7: The display means 15 displays the determination result of the quality of the engine 2 and the evaluation values b1 to bn.

In this manner, by determining the quality of the sound of the engine 2, the engine sound of the entire engine 2 can be comprehensively evaluated, and it is possible to determine whether the engine 2 is valid or not. Furthermore, by adjusting the weights α1 to αn, the senses of a skilled worker can be input, and the quality of the engine 2 can be automatically determined from then on. Therefore, variations in the quality of the engine 2 can be eliminated, the shortage of skilled workers can be compensated for, and the workers can be freed from the harsh environment during the engine 2 test. Furthermore, for each abnormality cause, for example, cause A can be evaluated in a range of 0 to 1, and the cause of the abnormal sound can be estimated.

[0013] The judgment result of the judgment means 14 can not only be displayed, but also output to a host computer.

[0014]

As explained above, according to the present invention, the engine sound detection signal of the microphone and the rotation speed detection signal of the tachometer are input, and, for example, under the condition that the rotation speed is constant,
It is possible to detect engine noise that exceeds a threshold and determine whether the engine sound is good or bad based on the judgment criteria, which can eliminate variations in engine quality and compensate for the lack of skilled workers. It is possible to relieve workers from the harsh environment during operation.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of engine quality determination equipment in an embodiment of the present invention.

FIG. 2 is a block diagram of a quality determination device according to an embodiment of the present invention.

FIG. 3 is a frequency characteristic diagram of the engine sound.

FIG. 4 is an abnormal frequency characteristic diagram of the engine sound.

[Explanation of symbols]

1 Test bench 2 Engine 3 Tachometer 4. Microphone 5. Good/failure judgment device 7 Rotation speed determination means 8 Frequency analysis means 10 Threshold setting means 11 Abnormal value setting means 12 First evaluation means 13 Second evaluation means 14 Judgment means 15 Display means

Claims (1)

[Claims] 1. A microphone installed near an engine to be measured to detect engine sound, a tachometer to detect the rotational speed of the engine to be measured, an engine sound detection signal from the microphone and a rotational speed detection from the tachometer. Engine quality determination equipment equipped with a quality detection device that inputs signals and detects the quality of engine sound based on criteria.