JP3305773B2 - Seizure prediction device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting a seizure by detecting vibration of a cylinder block.

[0002]

2. Description of the Related Art In order to always operate an internal combustion engine in a good state, appropriate maintenance and inspection are necessary. Particularly, if a failure can be predicted and necessary measures can be taken in advance, an emergency stop or engine damage during operation is required. It is effective to prevent such serious failures and accidents as before. For this reason, for example, the starting time is monitored each time the engine is started, and it is possible to diagnose the presence or absence of a sign of a potential failure from the change in the starting time (see Japanese Patent Publication No.
No. 6017). Attempts have also been made to detect a sign of a specific failure from abnormal vibration, sound, temperature, etc., especially since seizure is a serious failure that may cause cylinder block damage, etc. Has been made.

For example, it has been reported that the liner vibration at the bottom dead center increases at the time of piston seizure, so that seizure can be predicted by detecting this. However, the increase of the liner vibration can be detected in actual use. Since it is only a few seconds before seizure occurs, it is not enough to prevent seizure. Also,
It has been reported that the noise and the vibration of the crankshaft increase when the scuffing spreads over the entire surface, but this is also a phenomenon that can be detected only immediately before burning. Therefore, none of these conventional ones can be used from the viewpoint of practical seizure prediction.

[0004]

The present invention focuses on such a problem, and detects a sign of the seizure well before the actual occurrence of the seizure, so that the practical use can prevent the occurrence of the seizure. The task was to develop a predictive technology.

[0005]

In order to achieve the above object, according to the present invention, a vibration sensor attached to a cylinder block of an engine and an output of the vibration sensor are taken out for each cylinder in an explosion stroke. Determining means for monitoring the amount of decrease in the vibration data of each of the cylinders, and determining that the corresponding cylinder is in a state immediately before the seizure of the piston when the amount of decrease exceeds a preset reference value; and And output means for outputting a result of the determination. In the case of an engine with a small number of cylinders, the acceleration sensor may be one. However, when the number of cylinders is large, the cylinder block is divided into at least two sections including an appropriate number of cylinders, and a vibration sensor is provided for each section. Attached. In the above-described determination process, it is preferable to extract a component in a frequency range within a range in which the seizure of the piston can be predicted, which is included in the vibration data of each cylinder, and monitor a decrease in data in this frequency range.

[0006]

The inventors of the present application have studied the vibration of the cylinder block when seizure occurs. The vibration acceleration of the cylinder block fluctuates from cycle to cycle, so it is difficult to use it as a criterion. Since it decreases over time, the inventors have found that this can be used as a criterion for determining a sign of burning, and invented the apparatus of the present application. That is, according to research, cylinders where seizure is about to occur reduce the lateral vibration of the cylinder block due to slap, and when using an acceleration sensor as a vibration sensor, for example, the vibration speed data integrating the output decreases, By detecting the output of the acceleration sensor for each explosion stroke of each cylinder and observing the state of the decrease, it is possible to accurately detect the sign of seizure. Further, even if a vibration speed sensor, a displacement sensor for detecting the amplitude displacement of vibration, or the like is used as the vibration sensor, a sign of burning can be detected in the same manner.

If the number of cylinders is large and the number of acceleration sensors is one, it becomes difficult to detect the vibration of a distant cylinder. However, by installing a vibration sensor for each section by dividing the cylinder block, It is possible to appropriately detect the vibration of the cylinder. Further, there is a range of frequency components in which the seizure of the piston can be predicted according to the size of the cylinder bore of the engine. The vibration speed data of the cylinder block accompanying the slap is, for example, almost 1 in a diesel engine having a cylinder bore of 150 mm. ~ 3kHz
Since the frequency component in the range of is used, the precursor of burn-in can be detected more clearly by using the reduction amount of the data in the frequency domain corresponding to the size of the cylinder bore in comparison with the reference value. Can be.

[0008]

Next, one embodiment shown in the drawings will be described. FIG.
Is a block diagram of the embodiment device, 1 is an internal combustion engine, 2 is an acceleration sensor attached to its cylinder block,
3 is a top pulse sensor, 4 is a rotary pulse sensor, 5 is an integrator, 6 is a pulse multiplier, 7 is a gate pulser, 8 is a bandpass filter, 9 is an effective value calculator, 10
Is a comparator, and 11 is an XY plotter. As shown
The acceleration signal S ₁ output from the acceleration sensor 2 is output from the integrator 5
, Is converted into a speed signal S ₂ and input to the gate pulser 7. The pulse multiplier 6 receives the top pulse signal P ₁ of the top pulse sensor 3 and the rotation pulse sensor 4.
It is the input rotation pulse signal P _2, the trigger pulse P ₃ corresponding thereto are outputted with respect Getoparusa 7 in synchronization with the explosion stroke of each cylinder.

Hereinafter, the internal combustion engine 1 has a cylinder bore of 150 m.
m six-cylinder diesel engine, in which two acceleration sensors 2 are used as shown in the figure, one sensor sharing the first to third cylinders, and the other sharing the fourth to sixth cylinders. In the case where the fifth embodiment is configured, for example, an operation when the cooling oil in the fifth cylinder stops and seizure occurs in the fifth cylinder will be described.

[0010] Getoparusa by Figure 3 (a) vibration original waveform detected by the acceleration sensor 2 to share the fourth to sixth cylinders, (b) the trigger pulse P ₃ in synchronization with the explosion stroke of the fifth cylinder 7 There is shown a cut waveform cutting out the waveforms of the fifth cylinder, respectively, from Getoparusa 7 is output cylinder vibration velocity signal S ₃ that cut out portions of the period T ₅ from the waveform of (a). T ₄ and T ₆ similarly denote periods in which respective waveforms are cut out in synchronization with the explosion strokes of the fourth and sixth cylinders. Here, when observing the state of change in the output of the acceleration sensor 2 when the cooling oil of the fifth cylinder is stopped, whereas not observed significant change remains acceleration signals S ₁ or speed signal S _2, Speed signal S ₂
The cylinder vibration velocity signal S ₃ of the fifth cylinder cut from is the significant change appears. In addition, as a vibration sensor for detecting this change, a speed sensor or a displacement sensor can be used in addition to the above-described acceleration sensor.

FIG. 4 is a frequency distribution diagram showing this state. FIG. 4A shows a normal state immediately before the cooling oil stops, FIG. 4B shows a state one minute after the cooling oil stops, and FIG. Two minutes later, the state immediately before baking is shown, and (d) shows the state when baking occurs. That is, comparing these figures, the signal level hardly changes in the frequency region lower than around 1 kHz, whereas in the region indicated by A where the frequency is higher than (1), (a) is (a). )), And (c) further lowers. This is because although the vibration of the cylinder block includes the vibration associated with the explosion combustion and the vibration associated with the slap, the frequency component of the vibration associated with the explosion combustion is mainly about 1.5 kHz or less as shown in FIG. On the other hand, the frequency components of the vibration caused by the slap are distributed in the range of about 1 kHz to 3 kHz, and the component in the region A decreases because the lateral vibration due to the slap decreases as the burning state approaches. Conceivable.

In order to detect this change, in this embodiment, a band-pass filter 8 having a pass band of 1 to ₃ kHz is used, and the cylinder-specific vibration speed signal S ₃ cut out by the gate pulser 7 is passed through this filter 8. Another vibration speed signal S ₃ ′ is obtained, and the effective value calculator 9 outputs the effective value signal S _{4 ′.}
Has been converted to. Then, as compared with a preset reference value B in the comparator 10 so, when the amount of decrease in the effective value signal S ₄ exceeds the reference value B, the corresponding cylinder, i.e. the fifth cylinder piston seizure and of outputting the prediction signal S ₅ it is determined that a state immediately before, an alarm by using the prediction signal S _5, or emergency stops the engine 1.

Although the above description is for the fifth cylinder, the first to third cylinders detected by the acceleration sensor 2 in addition to the fourth and sixth cylinders are actually shown in FIG. Needless to say, the same processing is performed on the waveform cut out in the periods T ₄ , T _6, etc. illustrated in FIG. The pass band of the band-pass filter 8 is for a diesel engine having a cylinder bore of 150 mm. For example, 1.5 to 4 kHz is suitable for a diesel engine having a cylinder bore of 100 mm. It is desirable to select from 5 to 2 kHz.

The XY plotter 11 records the state of change of the effective value signal S ₄ obtained by such processing, and FIG. 6 exemplifies the state of change of the recorded effective value signal S _4. It is. (a) shows the change in the fifth cylinder, and (b) shows the change in the sixth cylinder. In the fifth cylinder in which the cooling oil has stopped, the signal level sharply drops from the cooling oil stop time and the seizure occurs. While the low level is maintained until immediately before the occurrence, the signal level does not decrease at all in the adjacent sixth cylinder.

That is, it is possible to detect a cylinder in which seizure may occur in the above processing.
By setting the reference value B to an appropriate value, this decrease in the signal level can be quickly detected. And since there is more than one minute before burning, it is possible to take measures such as emergency stop of the engine 1 by that time.
Seizure can be prevented beforehand. The decrease in the signal level may be detected not by a difference from the normal value but by a ratio. In this case, when the signal level decreases to, for example, about 60 to 70% of the normal value, the ratio is determined so as to be a sign of burning. You just have to choose.

FIGS. 7A and 7B show the results of comparison of the signal levels at each stage of the signal processing in a normal state, one minute after the cooling oil stops, and each state immediately before burning. FIG. 7A shows the acceleration of the acceleration sensor 2. When the signal S ₁ is converted to the speed signal S ₂ via the integrator 5 and the signal is simply compared, (b) is obtained when the signal of the fifth cylinder is cut out by the gate pulser 7 and compared.
(c) shows the case where the signals after passing through the band-pass filter 8 are compared. In (a), it is difficult to accurately detect the signal level because it is small, but in (b), the signal level is quite remarkable, and it is necessary to detect a cylinder that may cause seizure at this stage. Is possible. Further, at the stage (c), the signal level is further remarkably lowered, and it is considered that it is preferable to perform the filter processing as in the embodiment in order to perform accurate detection.

FIG. 1 is a block diagram of an embodiment, and an apparatus embodying the present invention is not limited to the configuration of FIG. 1, but may have a basic configuration as exemplified in FIG. I just need. That is, 15 is a sensor unit having a plurality of sensors 15a, 16 is a channel selector for selecting its output, 17 is an integrator, 18 is a gate circuit, 19 is a filter, and 20 is an output device.
21. It should be noted that the integrator 17, the gate circuit 18, the filter 19
It is convenient to provide the changeover switches 22, 23 and 24 in order to selectively use the.

Although the above embodiment is an example in which an acceleration sensor is used as a vibration sensor, a speed signal may be directly input to the gate pulser 7 without passing through the integrator 5 using a speed sensor. Alternatively, when a displacement sensor is used, the integrator 5 may be changed to a differentiator, and a speed signal may be input to the gate pulser. Further, after detecting the acceleration, velocity or displacement, the signal can be converted into an appropriate signal format to detect a sign of burning as in the above embodiment.

[0019]

As is apparent from the above description, according to the present invention, the vibration sensor is mounted on the cylinder block of the engine, and the output is taken out for each cylinder during the explosion stroke, and the amount of reduction in the vibration data of each cylinder is monitored. When this exceeds a preset reference value, it is determined that the corresponding cylinder is in a state immediately before the seizure of the piston. In this way, the vibration of the cylinder block, which is effective in predicting seizure, is taken out by appropriate processing, so that signs of seizure can be detected accurately, and the cylinder block can be stopped urgently before burning, for example, by stopping the engine. It is possible to prevent seizure, which is a serious failure that causes breakage of the product.

Further, by dividing the cylinder block into at least two sections each including an appropriate number of cylinders and attaching a vibration sensor to each section, the vibration of each cylinder is selectively detected in an engine having a large number of cylinders. can do. Further, in the above-described determination processing, by extracting a component in a frequency range of a range in which the seizure of the piston included in the vibration data of each cylinder can be predicted and monitoring the decrease amount, it is possible to more accurately detect the sign of seizure. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a block diagram showing a basic configuration of the present invention.

FIG. 3 is a diagram of a vibration waveform and a cut-out waveform diagram detected by an acceleration sensor.

FIG. 4 is a frequency distribution diagram of a vibration velocity signal.

FIG. 5 is a frequency distribution diagram of a vibration speed signal of a cylinder block.

FIG. 6 is a diagram illustrating a change state of an effective value signal;

FIG. 7 is a diagram comparing a change state of a signal level.

[Explanation of symbols]

1 internal combustion engine 2 acceleration sensor 5 integrator 7 Getoparusa 8 bandpass filter 9 rms calculator 10 comparator S ₁ acceleration signal S ₂ speed signal S ₃ cylinder vibration velocity signal S ₄ rms signal S ₅ prediction signal

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F02B 77/08 F02D 45/00 G01M 15/00

Claims (3)

(57) [Claims] 1. A vibration sensor attached to a cylinder block of an engine, an output of the vibration sensor is taken out for each explosion stroke of each cylinder, and a reduction amount of vibration data of each cylinder is monitored to set the reduction amount in advance. An internal combustion engine comprising: a determination unit that determines that the corresponding cylinder is in a state immediately before the seizure of the piston when the reference value exceeds the reference value; and an output unit that outputs a determination result by the determination unit. Baking prediction device. 2. The burn-in prediction device for an internal combustion engine according to claim 1, wherein the cylinder block is divided into at least two sections including an appropriate number of cylinders, and a vibration sensor is attached to each section. 3. A component in a frequency range within a range in which seizure of a piston can be predicted included in vibration data of each cylinder is extracted.
3. The device according to claim 1, wherein said device is configured to monitor a decrease in data in said frequency range.