JP3644625B2 - Engine diagnostic device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine diagnostic apparatus that determines whether a valve clearance of an intake valve and an exhaust valve is good or not by operating the engine during the production process of the engine.
[0002]
[Prior art]
Conventionally, in the production process of an engine, in order to ensure shipping quality, the produced engine is operated to judge whether the clearance of the intake valve and the exhaust valve is good or bad, and if it is defective, it is readjusted.
[0003]
Conventionally, inspecting the quality of the valve clearance has been determined by listening to engine sound during operation by the inspector. However, in this case, the judgment is made by the sensory evaluation of the inspector, and therefore, when there are many temporary inspectors such as period inspectors and support inspectors from other departments, the evaluation criteria are set by each inspector. Unlike this, there will be variations in the engine shipping guarantee standards.
[0004]
As a method of quantitatively detecting the difference in sound that relied on the auditor's hearing and automatically judging whether the valve clearance is good or bad, the engine sound during operation is detected with a microphone, and the sound pressure signal is fast Fourier transformed. It is conceivable to obtain a frequency spectrum by (FFT) and make a determination based on the frequency spectrum. However, since the FFT processing is to obtain a frequency spectrum at discrete time, it is suitable for data analysis of signal components in a transient region where the frequency changes with time, such as engine noise caused by poor valve clearance. There will be no.
[0005]
On the other hand, in Japanese Patent Laid-Open No. 8-219955, sound generated from a device is detected by a microphone, the sound pressure signal is subjected to wavelet transform, which is a kind of time-frequency analysis, and the sound pressure level and frequency are set at the same time. There has been proposed a device diagnostic apparatus that uses three-dimensional data represented on an axis, and thereby quantitatively evaluates a generated sound.
[0006]
According to this diagnostic device, the sound pressure signal is wavelet transformed, so if applied to engine diagnosis, abnormal engine noise caused by poor valve clearance can be captured quantitatively, and the quality of the valve clearance is automatically determined. Can be determined.
[0007]
[Problems to be solved by the invention]
However, according to the study by the present inventor, when an engine in a production process is to be diagnosed by applying the above-described diagnostic device, the valve sound that is the object of diagnosis is detected from the engine operated in a closed operation bench. In addition, various sounds such as injector sound, belt rubbing sound, dynamo rotation sound, exhaust sound, and vent sound are mixed, making it difficult to distinguish the signals related to the valve sound, and incorrect and incorrect valve clearance. There is a risk of triggering a decision.
[0008]
In addition, if only the ignition signal timing of a predetermined cylinder is used as a measurement trigger in order to extract a signal related to the valve sound, valve signal data (clearance vibration level) for the front and rear sides of each cylinder. 6 are different in position on the time axis t, as shown in FIG. 6, they can be detected separately. However, when the vibration levels are the same, FIG. As shown in FIG. 5, since the vibration levels are combined and appear on the time axis t, the two cannot be detected separately.
[0009]
Accordingly, an object of the present invention made in view of such a point is to provide an engine diagnostic apparatus that can always accurately determine the valve clearance.
[0010]
[Means for Solving the Problems]
The invention of the engine diagnostic apparatus according to claim 1, which achieves the above object, includes a plurality of vibration detecting means for detecting vibrations of the engine itself operating in the vicinity of each valve of the engine, and each of the vibration detecting means. A plurality of signal processing means for processing each engine vibration signal to extract a valve vibration signal related to driving of the corresponding valve, a cam angle detection signal and a crank angle detection signal from the engine control unit, and a pre-input cam profile Timing detection means for detecting camshaft timing indicating the range of the cam opening / closing ramp portion and valve lift portion corresponding to each valve based on the data, and valve clearance based on the correlation between the valve vibration signal and the camshaft timing And determining means for determining.
[0011]
According to the first aspect of the present invention, the vibration of the engine itself in operation is detected by the corresponding vibration detecting means in the vicinity of each valve, and the valve vibration related to the driving of the valve by the corresponding signal processing means from the engine vibration signal. Since the signal is extracted, it is possible to make it less susceptible to disturbances such as when detecting sound. In the determination means, the camshaft detected by the timing detection means based on each extracted valve vibration signal, the cam angle detection signal and crank angle detection signal from the engine control unit, and the cam profile data inputted in advance. Since the valve clearance is determined based on the correlation with the timing, even if the levels of the valve vibration signals on the front side and the rear side of each cylinder are the same, they can be detected separately. Therefore, it is possible to always accurately determine the valve clearance.
[0012]
According to a second aspect of the present invention, in the engine diagnostic apparatus according to the first aspect, each of the vibration detecting means includes an acceleration pickup, and the acceleration pickup is pressed against a rocker cover near the corresponding valve via the damper means. It is characterized by doing so.
[0013]
According to the invention of claim 2, since the acceleration pickup is pressed against the rocker cover in the vicinity of each valve via the damper means, it is possible to detect with high sensitivity the engine vibration including the vibration of the corresponding valve by each acceleration pickup. It becomes.
[0014]
According to a third aspect of the present invention, in the engine diagnostic apparatus according to the first or second aspect, each of the signal processing means has a specific frequency band related to driving of a valve from an engine vibration signal from the corresponding vibration detection means. A bandpass filter that extracts components, a squarer that squares the output of the bandpass filter, and a low-pass that removes a high-frequency component from the output signal of the squarer and outputs a valve vibration signal related to driving of the valve And a filter.
[0015]
According to the invention of claim 3, it is possible to extract a desired valve vibration signal included in the engine vibration signal from the vibration detecting means with a simple circuit configuration.
[0016]
According to a fourth aspect of the present invention, in the engine diagnostic apparatus according to any one of the first to third aspects, the determination means corresponds to the cam opening / closing ramp portion and the valve lift portion corresponding to each valve of the camshaft timing. The valve vibration signal obtained from the signal processing means is compared with a reference value set in advance based on the valve vibration signal obtained from the signal processing means when the valve clearance is in the normal range, and the valve based on the comparison result The clearance is determined.
[0017]
According to the fourth aspect of the present invention, the valve clearance of the engine to be diagnosed is judged as good or bad with a simple configuration in which a valve vibration signal obtained for an engine whose valve clearance is in a normal range, for example, an allowable limit value, is stored in advance. Can be accurately determined.
[0018]
According to a fifth aspect of the present invention, in the engine diagnostic apparatus according to any one of the first to fourth aspects of the present invention, there is provided display means for displaying a valve having a defective clearance in an identifiable manner based on a determination result by the determination means.
[0019]
According to the fifth aspect of the present invention, since the valve with a defective clearance is displayed on the display means so as to be identifiable, it can be easily dealt with.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of an engine diagnostic apparatus of the present invention will be described in detail with reference to FIGS. 1 to 5.
[0021]
1 is a block diagram showing a schematic configuration of an engine diagnostic device, FIG. 2 is a partial plan view showing a valve position of the engine shown in FIG. 1, FIG. 3 is a partial sectional view of the engine, and FIG. 4 is a signal processing shown in FIG. FIG. 5 is a diagram showing the camshaft timing detected by the timing detection circuit.
[0022]
Reference numeral 1 indicates a known engine of, for example, a horizontally opposed four-cylinder twin cam 16 valve, where # 1 indicates a first cylinder, # 2 indicates a second cylinder, # 3 indicates a third cylinder, and # 4 indicates a fourth cylinder. Yes. Each cylinder of the engine 1 has two intake (INT) front valves 2a and an INT rear valve 2b, and two exhausts, as shown in FIG. 2 for valve positions in the first cylinder # 1 and the third cylinder # 3. (EXH) A front valve 3a and an EXH rear valve 3b are provided.
[0023]
As shown in FIG. 3 for example, one INT front valve 2a and one EXH front valve 3a in one cylinder, each valve is connected via a cam 5a and rocker arms 6a and 6b corresponding to the rotation of the camshaft 5. To be driven. In FIG. 3, 7a and 7b are rocker shafts, 8 is a rocker cover, 9 is a cylinder head, 10a and 10b are intake and exhaust ports formed in the cylinder head 9, 11 is a cylinder block, 12 is a piston, 13 Indicates a combustion chamber.
[0024]
In the present embodiment, in the engine production process, in order to determine whether the valve clearance of each valve of the engine 1 is good or bad, an acceleration pickup as an example of vibration detecting means is provided on each rocker cover 8 near each valve of the engine 1 on the operation bench. The vibration of the engine itself during operation is detected by pressing 21. For example, as shown in FIG. 3, each acceleration pickup 21 is attached to the tip of a cylinder 22 having a damper mechanism as a damper means, and is pressed against the rocker cover 8 near the corresponding valve. In FIG. 1, only one acceleration pickup 21 is shown for each cylinder in order to simplify the drawing.
[0025]
The engine vibration signal detected by each acceleration pickup 21 is amplified by the amplifier 25 and supplied to the signal processing circuit 26. The amplifier 25 and the signal processing circuit 26 constitute signal processing means according to the present embodiment. The signal processing circuit 26 includes a band-pass filter (BPF) 27, a squarer 28, and a low-pass filter (LPF) 29, and outputs the engine vibration signal shown in FIG. 4 (b), a specific frequency band component related to the driving of the valve is extracted, and the output of the BPF 27 is squared by the squarer 28 as shown in FIG. 4 (c). Then, the high frequency component is removed by the LPF 29 to obtain a valve vibration signal related to the driving of the valve as shown in FIG. In FIG. 1, an amplifier 25 and a signal processing circuit 26 corresponding to one acceleration pickup 21 are shown to simplify the drawing. The output of the signal processing circuit 26 corresponding to each acceleration pickup 21 is supplied to the determination circuit 31.
[0026]
On the other hand, a cam angle detection signal and a crank angle detection signal detected by an engine control unit (ECU) 32 that controls the operation of the engine 1 are supplied to a timing detection circuit 33 as timing detection means. The cam profile data of the camshaft 5 shown in FIG. 3 is input in advance to the timing detection circuit 33. Here, based on the cam angle detection signal, the crank angle detection signal and the cam profile data from the ECU 32, the timing detection circuit 33 shown in FIG. As shown, camshaft timing indicating the range of the cam opening / closing ramp portion and valve lift portion corresponding to each valve is detected, and the detected camshaft timing signal is supplied to a determination circuit 31 as a determination means.
[0027]
The determination circuit 31 calculates the correlation between the valve vibration signal from each signal processing circuit 26 and the camshaft timing from the timing detection circuit 33, and determines the valve clearance based on the calculation result.
[0028]
Here, in the case of a valve having a large valve clearance, the timing for opening the valve is delayed, so that a valve vibration signal appears in the valve lift portion immediately after the cam opening ramp, and the timing for closing the valve is also accelerated, so that the cam closing A valve vibration signal appears at the valve lift immediately before the ramp. Therefore, in the present embodiment, a valve vibration signal obtained for an engine whose valve clearance is in a normal range, for example, an allowable limit value, is preset and stored as a reference value, and the camshaft timing signal from the timing detection circuit 33 is stored. The valve vibration signal from the corresponding signal processing circuit 26 is compared with the reference value in the range of the cam opening / closing lamp portion and the valve lift portion corresponding to each valve, and the valve whose valve vibration signal exceeds the reference value is compared. Judged as poor clearance.
[0029]
The determination result in the determination circuit 31 is supplied to a determination result display circuit 35 having a display lamp corresponding to each valve, and the display lamp corresponding to the valve with a defective clearance is turned on.
[0030]
Thus, according to the present embodiment, the acceleration pickup 21 is pressed against the rocker cover 8 in the vicinity of each valve to detect the vibration of the operating engine itself, and the corresponding signal processing circuit is determined from the engine vibration signal. Since the valve vibration signal related to the driving of the valve is extracted at 26, the vibration signal of the corresponding valve can be detected with high sensitivity without being affected by the disturbance as in the case of detecting the sound. The valve vibration signal is a camshaft timing detected by the timing detection circuit 33 based on the cam angle detection signal and the crank angle detection signal from the ECU 32 and the cam profile data of the camshaft 5 of the engine 1 to be diagnosed inputted in advance. Based on this, the determination circuit 31 determines the valve clearance by comparing with a preset reference value. In, the level of the valve vibration signal between the front side and the rear side of the cylinders are the same, can be detected by distinguishing the two, it is possible to determine the valve clearance always accurately.
[0031]
In addition, according to the determination result in the determination circuit 31, the indicator lamp corresponding to each valve of the determination result display circuit 35 is turned on when the clearance is defective, so that the inspector can easily identify the defective clearance valve. Can be dealt with quickly.
[0032]
The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention. For example, the engine model can be determined by the ECU, and the camshaft timing can be detected based on the cam profile data of the corresponding engine based on the determination result, so that a wide variety of engines can be diagnosed.
[0033]
【The invention's effect】
According to the engine diagnostic apparatus of the present invention described above, vibrations of the engine itself operating in the vicinity of each valve are detected, and a valve vibration signal related to driving of the corresponding valve is extracted from each engine vibration signal. As a result, it can be made less susceptible to disturbances such as when detecting sound, and the extracted valve vibration signals, cam angle detection signals and crank angle detection signals from the engine control unit are input in advance. Since the valve clearance is determined based on the correlation with the camshaft timing detected based on the cam profile data, the level of the valve vibration signal on the front side and the rear side of each cylinder is the same. However, it is possible to detect both of them separately and always determine the valve clearance accurately. That.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of an embodiment of an engine diagnostic apparatus according to the present invention.
FIG. 2 is a partial plan view showing a valve position of the engine shown in FIG. 1;
3 is a partial cross-sectional view of the engine shown in FIG.
4 is a signal waveform diagram for explaining the operation of the signal processing circuit shown in FIG. 1; FIG.
FIG. 5 is a diagram showing camshaft timing detected by the timing detection circuit shown in FIG. 1;
FIG. 6 is a waveform diagram for explaining a case where the vibration levels of the front and rear valves are different in the conventional example.
FIG. 7 is a waveform diagram illustrating a case where the vibration levels of the front and rear valves are the same.
[Explanation of symbols]
1 Engine 2a INT front valve 2b INT rear valve 3a EXH front valve 3b EXH rear valve 5 Camshaft 5a Cam 6a, 6b Rocker arm 7b, 7b Rocker shaft 8 Rocker cover 9 Cylinder head 10a Intake port 10b Exhaust port 11 Cylinder block 12 Piston 13 Combustion chamber 21 Acceleration Pickup 22 Cylinder 25 Amplifier 26 Signal Processing Circuit 27 Band Pass Filter (BPF)
28 Squarer 29 Low-pass filter (LPF)
31 determination circuit 32 engine control unit (ECU)
33 Timing detection circuit 35 Judgment result display circuit

Claims (5)

A plurality of vibration detecting means for detecting vibrations of the engine itself operating in the vicinity of each valve of the engine,
A plurality of signal processing means for processing the engine vibration signals from the vibration detection means and extracting valve vibration signals related to driving of the corresponding valves;
Timing for detecting camshaft timing indicating the range of the cam opening / closing ramp portion and valve lift portion corresponding to each valve based on the cam angle detection signal and crank angle detection signal from the engine control unit and pre-input cam profile data Detection means;
An engine diagnosis apparatus comprising: a determination unit that determines a valve clearance based on a correlation between the valve vibration signal and the camshaft timing. 2. The engine diagnostic apparatus according to claim 1, wherein each of the vibration detecting means has an acceleration pickup, and the acceleration pickup is pressed against a rocker cover near the corresponding valve via a damper means. Each of the signal processing means includes a bandpass filter that extracts a component of a specific frequency band related to driving of the valve from an engine vibration signal from the corresponding vibration detection means, and a squarer that squares the output of the bandpass filter. And a low-pass filter that removes a high frequency component from the output signal of the squarer and outputs a valve vibration signal related to driving of the valve. . In the range of the cam opening / closing ramp portion and the valve lift portion corresponding to each valve at the camshaft timing, the determination means includes the valve vibration signal obtained from the corresponding signal processing means and the valve clearance in the normal range. 4. The engine diagnosis according to claim 1, wherein a reference value preset based on a valve vibration signal obtained from the signal processing means is compared, and a clearance of the valve is determined based on the comparison result. apparatus. 5. The engine diagnosis apparatus according to claim 1, further comprising display means for displaying a valve having a defective clearance so as to be identifiable based on a determination result by the determination means.

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