JPH1194705A - Method for diagnosing abnormal cylinder and joint structure of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To judge abnormal cylinders such as cylinders not ignited, cylinders with nonuniform internal pressures, etc., by comparing a deviation from an internal pressure value or an internal pressure average value of each cylinder with a preset reference level or the like. SOLUTION: A rotation output of an output shaft 1A of a diesel engine 1 drives a propeller shaft 3 via a rubber joint 2. The rotation of the propeller shaft 3 rotates a propeller 4, thereby obtaining a propulsion force. A signal- processing alarm display part 9 constituted of a computer or the like takes a rotational frequency signal detected at a tachometer meter 5 and also an internal pressure of each cylinder 71 -7N measured by a pressure sensor 61 -6N fitted to the cylinder 71 -7N, and processed the same. In other words, a deviation from an internal pressure value or an internal pressure average value of each cylinder 71 -7N and a preliminarily set reference level or reference range corresponding to the detected rotational frequency are compared with each other, whereby whether each cylinder 71 -7N is normal or abnormal is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for diagnosing an abnormal cylinder and a joint structure of an internal combustion engine, and more particularly to a method for diagnosing an internal combustion engine in which an output shaft and a driven shaft of the internal combustion engine are connected by a rubber joint or another buffer joint. It is an object of the present invention to provide a method of diagnosing a joint structure and a method of diagnosing an abnormal cylinder such as a cylinder in which an internal combustion engine has not been ignited or has an in-cylinder pressure irregularity, using a main part of the method.

[0002]

2. Description of the Related Art In general, in a ship or the like, a propeller shaft (driven shaft) is connected to an output shaft (main shaft) of a diesel engine via a rubber joint, and the joint transmits driving torque from the output shaft to the propeller shaft. It is configured to drive a propeller, and adopts a rubber joint as the joint to absorb fluctuations in engine torque and to smoothly rotate the propeller shaft. That is, the rubber joint absorbs the intermittent explosion of the engine, for example, the misfiring of each cylinder, or the torque fluctuation caused by the abnormal fluctuation of the in-cylinder pressure of the cylinder. If excessive torque fluctuation exceeding the allowable torque repeatedly acts on the rubber joint, the rubber joint will crack and damage, and similarly, the rubber joint will blow up due to heat generated in the rubber due to excessive torque fluctuation. There is.

[0003] For this reason, as a conventional method for measuring torque fluctuation of a rubber joint of a diesel engine, a pulse corresponding to rotation is detected from a rotating shaft on an input side (spindle) and an output side (Flopeller shaft) of the rubber joint, and the main spindle is detected. There is a technique for calculating a rotation difference between the shaft and the floppy shaft, that is, a “shift” of rotation, and calculating a torque fluctuation amount based on the “shift”.

[0004]

However, in the method for determining the "deviation" of the rotation, it is not possible to correlate with the in-cylinder pressure or its variation, which is the main cause of fluctuation, and the method is permanently installed because of low reliability. In addition, there is a problem that the apparatus becomes complicated because the apparatus must be complicated.

[0005] The inventors of the present invention have assumed that when the curve of in-cylinder pressure of a normal cylinder is a prototype curve,
In diesel engines with rubber joints, focusing on the fact that torque fluctuations due to unignited cylinders or cylinders with abnormal in-cylinder pressure waveforms deviated from the prototype curve or power loss to the rubber joint greatly affect the wear of the rubber joint, If this unignited or abnormal in-cylinder pressure waveform can be detected, it is possible to obtain deterioration judgment information for judging the degree of deterioration of the rubber joint based on the magnitude and frequency of the excessive torque fluctuation that occurs. If the normal / abnormal display of the rubber joint is displayed based on
It has been found that it is possible to diagnose deterioration or wear of a rubber joint. However, at present, since no device for detecting unignited or abnormal in-cylinder pressure waveforms in each cylinder is provided, effective information on deterioration of the rubber joint cannot be extracted.

Accordingly, the present invention has been made in view of the above problems, and has found a diagnostic method capable of easily detecting an unignited or abnormal in-cylinder pressure waveform in each cylinder. It is an object of the present invention to provide a method for diagnosing an abnormal cylinder such as a cylinder in which an internal combustion engine has not been ignited or a cylinder in which pressure in a cylinder is not uniform. Another object of the present invention is to provide a method for diagnosing a joint structure of an internal combustion engine in which an output shaft and a driven shaft of the internal combustion engine are connected by a rubber joint or another buffer joint.

[0007]

According to the first aspect of the present invention,
In the method for diagnosing an abnormal cylinder such as an unignited cylinder of an internal combustion engine or an irregular cylinder pressure, the cylinder pressure is detected from each cylinder together with the rotation speed of the internal combustion engine, and the cylinder pressure value or the cylinder pressure of each cylinder is detected. It is characterized in that a deviation from the internal pressure average value is compared with a predetermined reference level or reference range corresponding to the detected rotation speed to determine whether each cylinder is normal or abnormal.

According to a second aspect of the present invention, there is provided a method of diagnosing a joint structure of an internal combustion engine in which an output shaft and a driven shaft of the internal combustion engine are connected by a rubber joint or another shock-absorbing joint. Detecting the in-cylinder pressure from the cylinder, and comparing the deviation from the in-cylinder pressure value or the in-cylinder pressure average value for each cylinder with a reference level (including a reference range) corresponding to the predetermined rotation speed detected in advance. The normal / abnormal state of each cylinder is detected and the torque fluctuation value obtained by converting the in-cylinder pressure of the abnormal cylinder into a torque fluctuation, and the allowable torque level of the joint corresponding to the detected rotation speed (the allowable range is also And whether the deviation from the torque fluctuation value or the standard torque level exceeds an allowable torque level.

According to the two inventions described above, when the abnormal cylinder of the internal combustion engine is determined, or when the torque fluctuation value is determined to exceed the allowable torque level (range), the administrator can, for example, , Maintenance and inspection of the fuel injection device of the corresponding cylinder, advancement and retardation of the fuel injection timing, adjustment of the opening and closing timing of the intake valve and exhaust valve, opening and closing amount, etc., and adjusting the combustion conditions of all cylinders, Wear of the buffer joint can be prevented.

The reference level or reference range corresponding to the detected rotation speed is defined as a timing at which the fuel injection timing of the fuel injection device supplied to each cylinder of the engine is appropriate, and the timing of opening and closing the intake valve and exhaust valve of each cylinder. Is the standard in-cylinder pressure of the cylinder when ignition is normal and the allowable range thereof.

In a general diesel engine, the linear motion of the piston due to the explosion of fuel in the cylinder is output as a force due to the rotational motion via the crankshaft. Also, when the rotation speed is high, the force (torque) output per unit time increases, and the load also increases. Therefore, the reference level or reference range of the in-cylinder pressure is set in accordance with the rotation speed.

[0012] Also, a normal or allowable torque level (including an allowable range) torque fluctuation corresponding to the detected rotational speed is represented by a vertical axis and a horizontal axis is represented by an engine rotational speed. Is evaluated and the degree of heat generation of the joint portion is evaluated based on the relationship between the load torque and the heat generation of the rubber joint measured in advance by an experiment, and set in accordance with the rotational speed. Here, the torque fluctuation value is obtained by multiplying the force calculated by the product of the difference between the in-cylinder pressure of the normal cylinder and the in-cylinder pressure of the unignited (abnormal) cylinder and the cross-sectional area of the cylinder by the crank arm length, and calculating the torque as a torque. The obtained value is the torque fluctuation value.

In addition to the rubber joint that absorbs torque fluctuations by rubber elasticity, a spring is mounted on the cushion joint in a circumferential direction, and the drive shaft is connected to the spring by semicircular seats provided at both ends of the spring. It also includes a shock-absorbing joint for transmitting torque to the driven shaft.

Next, the present invention will be described in detail. The present invention detects fluctuations in the cylinder pressure in each cylinder to determine misfiring or a fluctuation in torque of an abnormal cylinder that occurs when irregular ignition occurs or a deviation from a normal state, and diagnoses a wear state of a shock-absorbing joint based on this. The point is to do.

Conventionally, the displacement of the rotary shaft before and after the rubber joint is measured. However, in the present invention, the torque fluctuation which causes the wear of the rubber joint is largely affected by the unignition of the cylinder in the engine or the unevenness in the cylinder pressure. In addition, the non-ignition of the running engine or the variation in the cylinder pressure is detected, and the deviation from the normal waveform of the torque fluctuation waveform applied to the rubber joint, where the torque fluctuation is represented by the vertical axis and the engine speed is represented by the horizontal axis, is constantly measured. Grasp and evaluate. Then, it is determined whether the torque fluctuation value or the deviation is normal or exceeds the set range, and the fluctuation value is displayed. The judgment criterion can be evaluated in advance by a shaft-system torsional vibration calculation or the like.

Further, as in the first aspect of the present invention, it is also possible to simultaneously display a cylinder in which the engine is not ignited or a cylinder having an in-cylinder pressure irregularity, thereby determining that the engine is abnormal.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, and are merely illustrative examples. Only. FIG. 2 is a system configuration diagram according to an embodiment of the present invention in which a propeller shaft is attached to a diesel engine via a shock-absorbing joint. In the figure, reference numeral 1 denotes a diesel engine main body, 1A denotes an output shaft for extracting output from the engine 1, and 2 denotes a rubber. It is a joint. Reference numeral 3 denotes a propeller shaft, and an engine output shaft 1
The propeller shaft 3 is driven by the rotation output of A via the rubber joint 2, and the propeller 4 is rotated by the rotation of the propeller shaft 3 to obtain a propulsive force.

Numeral 9 denotes a signal processing alarm display section comprising a computer or the like, which bypasses and captures the actual engine speed (corresponding to engine load) signal detected by the tachometer 5 provided on the engine operation panel. together, performs processing to be described later by captures and cylinder pressure in each cylinder 7 which is measured using the pressure sensor 6 the attached to each cylinder 7 ₁ to _7-N of the diesel engine 1.

FIG. 1 is a system block diagram showing the main configuration of the signal processing alarm display section 9. Figure 11 is a cylinder pressure detector for all cylinders of the engine, measuring the direct cylinder pressure using the pressure sensor 6 ₁ to 6 _N attached to each cylinder 7 ₁ to _7-N shown in FIG. Reference numeral 12 denotes the actual engine speed (corresponding to the engine load) by bypassing the signal from the existing tachometer 5 of the engine.
Is a rotation speed detecting unit for detecting the rotation speed. Reference numeral 13 denotes a storage unit or an allowable torque level calculation unit that stores an allowable torque level (including an allowable range) corresponding to each rotation speed (load) determined in advance to finally evaluate the joint torque.
The joint allowable torque value or the standard torque value for each number of rotations applied to the engine rubber joint 2 is stored, and corresponding torque calculation data is output based on an instruction from the signal processing alarm display unit 9 side. Note that the allowable torque level (including the allowable range) or the standard torque value of the joint is determined from map data or calculation based on the load torque of the rubber joint 2 corresponding to the number of revolutions measured in advance and the degree of heat generation at the joint. It is stored in advance as an expression.

[0020] 14 in the cylinder pressure data processing unit for processing the cylinder pressure values for each cylinder 7 ₁ to _7-N detected by the in-cylinder pressure detection unit 11, the cylinder 7 as indicated by reference numeral 21 ₁ to _7-N Is converted by a DC rectifier into a DC level signal corresponding to the pressure value level.
The DC level signal is converted into a digital signal via an A / D converter, and then taken into an arithmetic circuit in the in-cylinder pressure data processing unit 14, where the average value of the in-cylinder pressure of all cylinders of the engine is obtained. Data processing such as obtaining in-cylinder pressure data for each of 7 _{1 to} 7 _N is performed. That is, in-cylinder pressure data processing unit 14, the digitally converted cylinder pressure value obtained by dividing the engine all cylinders of the average cylinder pressure 60 _AV expressions in the engine total number of cylinders obtained by adding the engine all cylinders fraction (6
_{0 AV = (60 1 + ...} + 60 N) / N, N: while calculating based on the engine number of cylinders), each cylinder 7 _1-7 digital converter for each _N is a cylinder pressure value 60 ₁ ... 60 _N Output to the comparison operation unit 15.

The comparison operation unit 15 receives the in-cylinder pressure data 60 _AV , 60 ₁ , 60 _N obtained by the in-cylinder pressure data processing unit 14 and the engine rotation signal (corresponding to the engine load) from the rotation speed detection unit 12. First, the standard in-cylinder pressure data N corresponding to the detected rotational speed (load) from the map data 20 stored in advance and the change data (normal lower limit level L) of the in-cylinder pressure value due to unignition in the cylinder are obtained. It is read and compared with the actual in-cylinder pressure value input from the in-cylinder pressure data processing unit 14. As a result the actual cylinder pressure value 60 ₁ of the cylinder 7 ₁ to _7-N, 60 _N is equal to or smaller than a lower limit of normal levels can be detected as abnormal cylinder when:.

When the abnormal cylinder is detected, the abnormal cylinder number corresponding to the abnormal cylinder number is blank-converted and displayed in the in-cylinder pressure abnormality display section 17 for displaying the abnormal cylinder number. The in-cylinder pressure data of the unignited (abnormal) cylinder is output to the calculation / evaluation unit 16. In the figure, when all cylinders are normal in the frame of the abnormal display section 17, the lower row outside the frame is No. The case where one cylinder is abnormal is shown.

The torque fluctuation calculation / evaluation unit 16 calculates a torque fluctuation value based on the in-cylinder pressure of the unignited (abnormal) cylinder detected by the comparison operation unit 15. Here, the torque fluctuation value is a force calculated by a product of a difference between a preset cylinder pressure value of a normal cylinder corresponding to the detected rotation speed and a cylinder pressure of an unignited (abnormal) cylinder and a cylinder sectional area. Is further multiplied by the crank arm length to obtain a torque variation value. Then, the torque fluctuation calculating / evaluating unit 16 reads out the joint standard torque value or the joint torque allowable level value corresponding to each rotation speed (load) for evaluating the joint torque from the torque level calculating unit 13 and reads the unignited state. (Unusual) Evaluate by comparing the in-cylinder pressure data of the cylinder with the value converted into torque fluctuation. That is, in the torque fluctuation calculation / evaluation unit 16,
Since the torque fluctuation value applied to the rubber joint 2 during the actual operation of the engine is calculated, a comparison with the coupling standard torque value or the coupling torque allowable level value is performed, and the deviation from the torque fluctuation value or the standard torque value indicates the allowable level. If it exceeds, it is determined to be abnormal and displayed on the rubber joint abnormality display section 18.

The display unit 18 has a system capable of outputting an alarm when the torque fluctuation value is out of a normal range or an allowable range. After the abnormality warning, for example, the maintenance condition of the fuel injection device, the advance and retard of the fuel injection timing, the opening / closing timing of the intake and exhaust valves, the opening / closing amount, and the like are adjusted, and the combustion conditions for the corresponding cylinder are adjusted.

Next, the operation of the present embodiment will be described. As described above, the in-cylinder pressure data processing unit 14 includes the pressure detection unit 1
Than 1, takes in-cylinder pressure signal from the cylinders 7 ₁ to _7-N (pulsating pulse waveform), after the in-cylinder pressure pulsating direct current level signal and the digital conversion, the in-cylinder average pressure of the engine all cylinders after calculating the in-cylinder pressure data for each cylinder 7 ₁ to _7-N, and outputs the comparison operation unit 15.

In the comparison operation unit 15, after the engine speed signal is captured by the engine speed detection unit 12 for grasping the engine load, the engine speed corresponding to the engine speed given as a prototype curve from the map data 20 is obtained. The standard in-cylinder pressure data N and the normal lower limit level L are read out and compared with the actual in-cylinder pressure value input from the in-cylinder pressure data processing unit 14 for evaluation. In the present embodiment, a difference between the standard pressure and the actual in-cylinder pressure value is calculated, and a program that can determine “low” for each of the cylinders 7 _{1 to} 7 _N using a computer program. It has been set.

Next, the in-cylinder pressure of each of the cylinders 7 _{1 to} 7 _N becomes “
When there is a cylinder with "low", all cylinders given as a prototype curve are compared with the normal (standard) in-cylinder pressure value, and the cylinder is regarded as unignited or abnormal, and unignited. (Unusual) The cylinder is displayed on the in-cylinder pressure abnormality display section 17.

Next, in order to finally evaluate the joint torque, a joint standard torque value corresponding to each rotation speed (load) is obtained in advance by the torque level calculating section 13 and this is calculated by the torque fluctuation calculating / evaluating section 16. And evaluated as the torque fluctuation value of the above-mentioned unignited (abnormal) cylinder. That is, since the torque fluctuation value applied to the rubber joint 2 during the actual operation of the engine is calculated by the torque fluctuation calculation / evaluation unit 16, the torque fluctuation value is compared with the standard torque value of the coupling or the allowable torque level value of the coupling. Alternatively, when the deviation from the standard torque value exceeds the allowable level, it is determined that the abnormality is abnormal, and is displayed on the rubber joint abnormality display section 18.

Therefore, in this embodiment, each of the cylinders 7 ₁ to 7 ₁
The unfired (abnormal) cylinder can be determined from the magnitude (difference) of the in-cylinder pressure value from 7 _N, and the torque fluctuation value of the engine is calculated from the in-cylinder pressure data of the unignited cylinder, and the engine speed is calculated. The level of torque fluctuation can be evaluated from the allowable value of the joint torque corresponding to (load).

[0030]

As described above, according to the first aspect of the present invention, the uninitiated cylinder is discriminated by constantly detecting and evaluating the in-cylinder pressure in each cylinder during operation of the engine having the rubber joint. Is possible. According to the second aspect of the present invention, the torque fluctuation value of the engine is estimated and calculated by detecting the unignited cylinder, and the torque fluctuation value applied to the engine rubber joint is displayed and monitored. Here, an allowable torque set value of the rubber joint is provided, and when the allowable torque set value is out of the allowable value, an alarm is displayed to enable protection of the rubber joint.

[Brief description of the drawings]

FIG. 1 is a system block diagram showing a configuration of a main part of a signal processing alarm display unit of FIG. 2;

FIG. 2 is a system configuration diagram according to an embodiment of the present invention in which a propeller shaft is attached to a diesel engine via a shock-absorbing joint.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Diesel engine (internal combustion engine) 1A Output shaft 2 Rubber joint 3 Propeller shaft 6 Pressure sensor 5 Revolution meter 7 Cylinder 9 Signal processing alarm display unit 11 In-cylinder pressure detection unit 12 Revolution detection unit 13 Joint torque calculation unit 14 In-cylinder Pressure data processing section 15 Comparison operation section 16 Torque fluctuation calculation / evaluation section 17 In-cylinder pressure abnormality display section 18 Rubber joint abnormality display section (display means)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02D 45/00368 F02D 45 / 00368S

Claims (2)

[Claims] 1. A method for diagnosing an abnormal cylinder such as an unignited cylinder of an internal combustion engine or a cylinder with irregular cylinder pressure, comprising: detecting a cylinder pressure together with a rotation speed of the internal combustion engine; A normal / non-normal state of each cylinder is determined by comparing a deviation from an internal pressure value or an average value of the in-cylinder pressure with a predetermined reference level (including a range) corresponding to the detected rotation speed. Of diagnosing abnormal cylinders of an internal combustion engine. 2. A method for diagnosing a joint structure of an internal combustion engine in which an output shaft and a driven shaft of the internal combustion engine are connected by a rubber joint or another shock-absorbing joint. And comparing the deviation from the in-cylinder pressure value or the in-cylinder pressure average value of each cylinder with a predetermined reference level (including a range) corresponding to the detected rotational speed, and comparing the normal / While detecting abnormalities, the torque fluctuation value obtained by converting the in-cylinder pressure of the abnormal cylinder into a torque fluctuation is compared with a standard or allowable torque level (including a range) of the joint corresponding to the detected rotation speed. And determining whether a deviation from the torque fluctuation value or a standard torque level exceeds an allowable torque level.