JPH06137163A - Seizure prediction device for internal combustion engine - Google Patents

Abstract

PURPOSE:To develop a practical prediction technique for sensing signs of seizure, thereby preventing seizure. CONSTITUTION:A vibration sensor is attached to a cylinder block of an engine 1. Its output data is then taken out in each explosion stroke in the respective cylinders. The data are compared in a comparator 10 to see whether a decrement of vibration data in each cylinder exceeds a reference value. The excess beyond it is determined as indicating that the corresponding cylinder is in a state just before seizure of the piston, so that a prediction signal is outputted from an output device. Vibration of a cylinder block effective for prediction of a seizure, is thus taken out by suitable processing, so that it becomes possible to detect the signs absolutely fairly before actual seizure, thereby preventing the seizure which is vital failure.

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 vibration of a cylinder block to predict seizure.

[0002]

2. Description of the Related Art In order for an internal combustion engine to always operate in good condition, proper maintenance and inspection are necessary. In particular, if a failure can be predicted and necessary measures can be taken in advance, an emergency stop or engine damage during operation can be expected. It is effective in preventing serious failures and accidents such as. For this reason, for example, the engine starting time is monitored every time the engine is started, and it is possible to diagnose the presence or absence of a sign of a potential failure from changes in the starting time (Japanese Patent Publication No.
No. 6017) is known. In addition, attempts have been made to detect the precursor of a specific failure from abnormal vibration, sound, temperature, etc. Especially, since seizure is a serious failure that causes damage to the cylinder block, many studies have been conducted on the precursor of seizure. Has been done.

For example, since it is reported that the liner vibration at the bottom dead center increases at the time of piston seizure, the seizure can be predicted by detecting this. However, it is actually possible to detect the increase in the liner vibration. Only a few seconds before the seizure occurs, it is too late to prevent the seizure. Also,
It has been reported that noise and crankshaft vibration increase when scuffing spreads over the entire surface, but this is a phenomenon that can only be detected just before seizure. Therefore, from the viewpoint of practical seizure prediction, none of these conventional ones can be used.

[0004]

SUMMARY OF THE INVENTION The present invention focuses on such a problem, and detects the precursor of the image sticking before the actual occurrence of the image sticking, and can prevent the image sticking from occurring. The task was to develop predictive technology.

[0005]

In order to achieve the above object, in the present invention, a vibration sensor attached to a cylinder block of an engine and the output of this vibration sensor are taken out for each explosion stroke of each cylinder and obtained. Determining means for observing a decrease amount of the vibration data of each cylinder, and determining that the corresponding cylinder is in a state of imprinting of the piston when the decrease amount exceeds a preset reference value; And an output unit that outputs the determination result according to. The above-mentioned acceleration sensor may be one in the case of an engine having a small number of cylinders, but in the case of a large number of cylinders, 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. It is attached. Further, in the above determination process, it is desirable to take out a component in the frequency region within the range where the piston seizure can be predicted, which is included in the vibration data of each cylinder, and monitor the amount of decrease in the data in this frequency region.

[0006]

The inventors of the present application have studied the vibration of the cylinder block when seizure occurs, and although the vibration acceleration of the cylinder block is difficult to use as a criterion for judgment because it varies significantly from cycle to cycle, the vibration speed is Since it decreases with the passage of time, the inventors of the present invention have invented the apparatus of the present application, finding that this can be used as a criterion for determining the precursor of image sticking. That is, according to the research, in the cylinder in which seizure is about to occur, the lateral vibration of the cylinder block accompanying the slap is reduced, and when an acceleration sensor, for example, is used as the vibration sensor, the vibration velocity data obtained by integrating the output is reduced. By taking out 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. In addition, if a vibration velocity sensor or a displacement sensor that detects the amplitude displacement of vibration is used as the vibration sensor, the sign of seizure can be detected in the same manner.

When the number of cylinders is large and the number of acceleration sensors is one, it becomes difficult to detect the vibration of the cylinders located at the distant position. However, by dividing the cylinder block and attaching the vibration sensor to each section, It is possible to properly detect the vibration of the cylinder. Further, there is a range of frequency components in which piston seizure can be predicted according to the size of the cylinder bore of the engine, and the vibration speed data of the cylinder block due to the above slap is almost 1 in a diesel engine having a cylinder bore of 150 mm, for example. To 3 kHz
Since it has a frequency component in the range of, it is possible to detect the sign of seizure more clearly by using the amount of decrease in the data in the frequency region corresponding to the size of such a cylinder bore for comparison with the reference value. You can

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment shown in the drawings will be described below. Figure 1
1 is a block diagram of an embodiment apparatus, 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 rotation 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 transferred to the integrator 5
After being converted into a speed signal S ₂ and input to the gate pulser 7, the pulse multiplier 6 has a top pulse signal P _{1 from} the top pulse sensor 3 and a rotation pulse sensor 4
The rotation pulse signal P ₂ is input, and the trigger pulse P ₃ corresponding thereto is output to the gate pulser 7 in synchronization with the explosion stroke of each cylinder.

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

FIG. 3 (a) is a vibration original waveform detected by the acceleration sensor 2 for the fourth to sixth cylinders, and FIG. 3 (b) is a gate pulser 7 by a trigger pulse P ₃ synchronized with the explosion stroke of the fifth cylinder. Shows the cut-out waveforms for cutting out the waveform of the fifth cylinder, and the gate pulser 7 outputs the cylinder-by-cylinder vibration velocity signal S _{3 obtained} by cutting out the portion of the period T ₅ from the waveform of (a). Note that T ₄ and T ₆ similarly indicate periods during which the respective waveforms are cut out in synchronization with the explosion strokes of the fourth cylinder and the sixth cylinder. Here, when observing the change state of the output of the acceleration sensor 2 when the cooling oil of the fifth cylinder is stopped, while the acceleration signal S ₁ or the speed signal S ₂ remains unchanged, Speed signal S ₂
A significant change appears in the cylinder-by-cylinder vibration velocity signal S ₃ of the fifth cylinder cut out from the above. As the vibration sensor for detecting this change, a speed sensor or a displacement sensor can be used in addition to the above acceleration sensor.

FIG. 4 is a frequency distribution diagram showing this state. (A) is a normal state immediately before the cooling oil is stopped, (b) is a state one minute after the cooling oil is stopped, and (c) is. The state immediately before baking after 2 minutes and the state at the time of occurrence of baking are shown in (d). That is, comparing these figures, there is almost no change in the signal level in the frequency region lower than around 1 kHz, whereas in the region indicated by A where the frequency is higher than that, in (b) (a) ), And in (c). This is because the vibration of the cylinder block includes the vibration associated with the explosive combustion and the vibration associated with the slap, but the frequency component of the vibration associated with the explosive combustion is mainly about 1.5 kHz or less as shown in FIG. On the other hand, the frequency component of the vibration associated with the slap is distributed in the range of about 1 kHz to 3 kHz, and the lateral vibration due to the slap decreases as the seizure state is approached, so the component in the area A decreases. Conceivable.

In order to detect this change, in the embodiment, a band pass filter 8 having a pass band of 1 to ₃ kHz is used, and the cylinder vibration speed signal S ₃ cut out by the gate pulser 7 is passed through the filter 8 to the cylinder. Another vibration velocity signal S ₃ ′ is used, and the effective value calculator 9 further uses the effective value signal S ₄
Has been converted to. Then, this is compared with a reference value B set in advance by the comparator 10, and when the amount of decrease in the effective value signal S ₄ exceeds the reference value B, the corresponding cylinder, that is, the fifth cylinder, has a piston seizure. The predictive signal S ₅ is output when it is determined that the engine 1 is in the imminent state, and an alarm is issued or the engine 1 is brought to an emergency stop using the predictive signal S ₅ .

Although the above description is for the fifth cylinder, actually, in addition to the fourth and sixth cylinders, the first to third cylinders detected by other acceleration sensors 2 are also shown in FIG. It goes without saying that the same processing is performed on the waveforms cut out in the periods T ₄ , T _{6 and the} like illustrated in FIG. The pass band of the band pass filter 8 is in the case of a diesel engine having a cylinder bore of 150 mm. For example, a diesel engine having a cylinder bore of 100 mm is preferably 1.5 to 4 kHz, and a cylinder bore having a cylinder bore of 280 mm has a pass band of 0. It is desirable to select 5 to 2 kHz.

The XY plotter 11 records the changing state of the effective value signal S ₄ obtained by such processing, and FIG. 6 illustrates the changing state of the recorded effective value signal S _4. Is. (a) shows the change of the 5th cylinder, and (b) shows the change of the 6th cylinder. In the 5th cylinder where the cooling oil stopped, the signal level drastically decreased from the cooling oil stop time and the seizure occurred. While the low level is maintained until immediately before the occurrence, the signal level does not drop at all in the adjacent sixth cylinder.

That is, it is possible to detect a cylinder in which seizure may occur by the above processing,
By setting the reference value B to an appropriate value, it is possible to quickly detect this decrease in signal level. Since there is a margin of 1 minute or more before printing, it is possible to take measures such as emergency stop of the engine 1 by that time.
It is possible to prevent seizure. The decrease in the signal level may be detected by the ratio instead of the difference from the normal value. In this case, the ratio is determined so as to be a precursor of the image sticking when the signal level decreases to about 60 to 70% of the normal value. You can select it.

FIG. 7 shows the comparison result of the signal levels at each stage of the signal processing in the normal state, after 1 minute of cooling oil stop, and immediately before the seizure. (A) 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, a simple comparison is made. (B) is a case where the gate pulser 7 cuts out the signal of the fifth cylinder, and then the comparison is made.
(c) shows the case where the signals after passing through the band pass filter 8 are compared. In (a), it is difficult to detect accurately because the signal level does not decrease so much.However, in (b), the signal level decreases considerably, and at this stage, it is necessary to detect cylinders that may cause seizure. Is possible. Further, at the stage of (c), the signal level is further remarkably lowered, and it is considered preferable to add the filter processing as in the embodiment in order to perform accurate detection.

Note that FIG. 1 is a block diagram of an embodiment, and an apparatus for carrying out the present invention is not limited to the configuration of FIG. 1 and may have a basic configuration as illustrated in FIG. Good. 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.
It is controlled by 21. In addition, the integrator 17, the gate circuit 18, and the filter 19 are selected according to the content of the signal processing.
It is convenient to provide change-over switches 22, 23 and 24 in order to selectively use the switch.

In the above-mentioned embodiment, the acceleration sensor is used as the vibration sensor, but the speed sensor may be used to directly input the speed signal to the gate pulser 7 without passing through the integrator 5, Alternatively, when a displacement sensor is used, the integrator 5 may be changed to a differentiator and a velocity 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 the sign of image sticking as in the above embodiment.

[0019]

As is apparent from the above description, according to the present invention, the vibration sensor is attached to the cylinder block of the engine, the output thereof is taken out for each explosion stroke of each cylinder, and the decrease amount of the vibration data of each cylinder is monitored. Then, when this exceeds a preset reference value, it is determined that the corresponding cylinder is in a state where the piston is on the verge of burning. In this way, the vibration of the cylinder block, which is effective in predicting seizure, is taken out by appropriate processing, so the precursor of seizure can be accurately detected, and the cylinder block can be stopped by an emergency stop before the seizure. It is possible to prevent seizure, which is a serious failure that causes damage to the product.

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

[Brief description of drawings]

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

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

FIG. 3 is a vibration waveform diagram and a cutout 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 velocity 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 changes in signal level.

[Explanation of symbols]

1 Internal Combustion Engine 2 Accelerometer 5 Integrator 7 Gate Pulser 8 Band Pass Filter 9 Effective Value Calculator 10 Comparator S ₁ Acceleration Signal S ₂ Speed Signal S ₃ Cylinder Vibration Speed Signal S ₄ Effective Value Signal S ₅ Prediction Signal

Claims (3)

[Claims] 1. A vibration sensor attached to a cylinder block of an engine, and an output of the vibration sensor is taken out for each explosion stroke of each cylinder, and a decrease amount of vibration data of each cylinder is monitored to set a decrease amount in advance. The internal combustion engine is characterized by comprising: a determination unit that determines that the cylinder is in a state where the piston is on the verge of seizure when the reference value is exceeded, and an output unit that outputs the determination result of the determination unit. Bake prediction device. 2. The seizure prediction device for an internal combustion engine according to claim 1, wherein the cylinder block is divided into at least two sections including a proper number of cylinders, and a vibration sensor is attached to each section. 3. A frequency domain component within a range where piston seizure can be predicted, which is included in vibration data of each cylinder, is extracted,
The seizure prediction device for an internal combustion engine according to claim 1 or 2, wherein the seizure prediction device is configured to monitor a decrease amount of data in the frequency region.