JPS6026164A - Trouble diagnoser for fuel injection pump - Google Patents

Abstract

PURPOSE:To quantitatively and easily find out the degree of drop in the function of a fuel injection pump, by providing a calculator which computes the ratios of the central voltages of respective electric signals corresponding to the vibrations of constituent parts, to the central valve of a reference electricity signal. CONSTITUTION:An accelerometer 3 is secured on the case of a fuel injection pump 1 by an adhesive to detect the vibrations of constituent parts in terms of electric signals corresponding to the vibrations. The electric signals are extracted through filters 7a-7d. A reference electricity signal is extracted through another filter 7h. A calculator 10 determines the ratios of the central values of the electric signals to the reference electricity signal. The ratios are shown on an indicator 12. As a result, the degree of drop in the function of the injection pump 1 can be quantitatively and easily found out.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a failure diagnosis device for a fuel injection pump of a diesel engine.

A diesel engine fuel injection pump (hereinafter abbreviated as injection pump) has the function of increasing the pressure of fuel oil and delivering the required amount at a set time. To perform this function, an injection pump mainly consists of a rotating camshaft, a reciprocating tappet, a rotating and reciprocating plunger, gears and control racks that control the amount of oil discharged, and a plunger seat, spring, and spring. It consists of parts such as seats, hair rings, and delivery valves. These components undergo mechanical deterioration over time, such as wear and breakage.If these parts deteriorate, the engine's fuel system may malfunction, engine startability deteriorates, knocking, insufficient output, unstable output, maximum output, etc. Phenomena such as the rotational speed not being obtained or too high, the idling rotational speed being unstable, and abnormal exhaust color appear.

In the case of an engine with multiple cylinders, there are tappets, plungers, springs, and other parts for each cylinder, so even if mechanical deterioration occurs in one cylinder, the engine as a whole will continue to operate normally. There are things to do.

Deterioration of overall engine function (state where rated output cannot be obtained)
In this case, it is necessary to investigate which system the problem is caused by, which part of that system it is caused by, and to what extent which parts of that part are contributing to the decline in function. was there.

Conventionally, the function inspection of this injection pump has been carried out by service personnel who judge based on the experience of the diesel engine based on the startability of the diesel engine, the level of output, the condition of the idle link, the diesel knocking noise, etc.

However, according to this judgment based on experience, each judgment factor includes malfunction phenomena from sources other than the injection pump, so it is difficult to judge the injection pump net, and it also includes subjectivity based on the experience of service personnel. In addition, in the case of multiple cylinders (4 cylinders, 6 cylinders, etc.), there are multiple pump parts of the injection pump, and it is difficult to determine which pump is malfunctioning. There is a drawback that it is not possible to quantitatively determine the extent to which the function of the pump corresponding to the number of injection pumps has deteriorated. Also,
In order to accurately determine the degree of functional decline, it is necessary to remove the temporary injection pump from the engine and examine it using a pliers test device, which also has the disadvantage of requiring a long period of time for inspection.

SUMMARY OF THE INVENTION In view of the above-mentioned points, an object of the present invention is to provide a device that can quantitatively and easily determine the degree of functional decline of an injection pump.

In order to achieve this object, the device of the present invention detects the vibration as an electric signal by gluing and fixing the acceleration i to the case of the injection pump. The signal and a reference electric signal that is not affected by aging of the injection pump are each extracted by a P-wave device, representative voltage values are determined from these electric signals, and the representative voltage value of each individual electric signal and the reference electric signal are determined. Requesting the ratio of the reference electrical signal to the representative electrical value from the arithmetic device;
The ratio is displayed on a display device.

The details of the present invention will be explained below with reference to embodiments shown in the drawings.

In FIG. 1, 1 is an injection pump, and 2 is a failure diagnosis device. The device 2 diagnoses failures by quantitatively evaluating the degree of mechanical deterioration of components of the injection pump. In other words, when the injection pump is operating, the camshaft rotates and the tappet and plunger reciprocate, and these parts strike and slide against each other, creating waves (sound, vibration, etc.) associated with the operation. The wave motion changes as mechanical deterioration of the internal parts of the injection pump occurs. Therefore, the present invention displays the degree of deterioration by detecting the degree of change in the wave, and since the frequency of the wave varies depending on each component, the wave at the frequency corresponding to each component is detected by a wave generator. , the degree of deterioration of each component can be evaluated.

The failure diagnosis device 2 includes an accelerometer 3 fixed to the case of the injection pump 1 with instant adhesive or the like, and the accelerometer 3.
and a main body 5 connected via a signal line 4. The accelerometer 3 converts vibrations during operation of the injection pump 1 into electrical signals, and is a new type of accelerometer with a frequency range of several Hz to 20K Ilz and a sensitivity of 20 to 40K.
mV/G (2,0~4゜0 mV/'m52)
I used one with linearity.

In the main body 5, 6 is an amplifier that amplifies the detected voltage signal of the accelerometer 3 to a level suitable for processing in a signal processing section, which will be described later, since the voltage signal is a minute voltage, and has a gain of about 20.
~40 dB was used.

7a to 7d are p wave generators that extract signals in a specific range of frequencies corresponding to components from the output signal of the amplifier 6, and 7L is a p-wave generator that extracts signals in a specific range of frequencies corresponding to components from the output signal of the amplifier 6. (This signal is unaffected by the natural vibration component of the injection pump, and exhibits the characteristic that the amount of change in potential of the signal hardly changes over time during the operation of the injection pump.) This is a bandpass ν wave generator that extracts a reference electrical signal (hereinafter referred to as reference electrical signal A).

The signals extracted by each of the P-wave devices 7a to 7d are signals corresponding to vibrations generated from parts as shown in the table below.

Each signal BE listed in the above table will be explained below.

Signal B is caused by the phenomenon of knocking together due to the gap between the cam part of the camshaft and the roller part of the tappet, and the vibration becomes large due to backlash, dents, wear, and seizure, and the settings for extracting the signal are necessary. Use a high-pass filter that passes signals above the frequency. .

Signal C is generated by a signal accompanying the revolution and rotation of the bearing part of the camshaft, and vibration increases due to deterioration phenomena such as mechanical deterioration, wear, electrolytic corrosion, seizure, flaking, cracking, and compaction. For signal extraction, a low-pass P-wave device is used that allows signals below a certain set frequency to pass through the outer ring, rolling elements, and inner ring.

Also, regarding the signal, the tappet, plunger seat, and plunger are pushed in one direction by a push spring, and the plunger seat may suffer mechanical deterioration, dents, or cracks, the tappet may have dents, cracks, or the plunger may be worn out. Phenomena such as dents, cracks, etc. occur, and the free length of the push spring changes. In addition, the push spring itself undergoes plastic deformation such as fatigue or breakage. The tappet, plunger seat, and plunger are pushed by a push spring, and when the injection pump operates, each part hits each other, causing a change in the free length of the spring, and an indentation.
The vibration increases due to deterioration phenomena such as cracks, and a band door filter 7C that passes a certain set frequency band is used to extract the signal.

The signal E generated by the delivery valve increases due to deterioration phenomena such as damage to the piston, seizure, and change in the free length of the push spring.
Use d.

Delivery valves, tappets, plunger seats, and P-wave devices used to detect vibrations of plungers are band P-wave devices and have the same type, but their masses and dimensions (sizes) are different, so their natural frequencies are different. , it is possible to distinguish between the two by changing the frequency band.

8 is a door wave device 7a to 7L as shown in FIGS. 2 to 5.
These are signal shapers that obtain smooth rectified signal envelope signals as shown in FIGS. 6 to 8 from the output signals of the P-wave generators, respectively, and the control device 11 selects which P-wave generator's output is to be shaped. This input circuit also includes the amplifier 6
It has a circuit 15 that directly inputs the output signal of. This circuit 15 is for passing an original signal when waveform observation is performed using a display device or the like as described later.

Reference numeral 9 denotes a signal converter that converts the peak voltage of the voltage that is the output signal of the signal shaper 8 into a digital value.

10 determines a representative value by sampling the digitized peak voltage, and determines a representative value of the reference electric signal;
This is an arithmetic device that calculates a ratio between the individual electric signal and a representative value. Reference numeral 12 denotes a reproducible recording device such as a magnetic medium or paper tape for recording the calculation results of the calculation device 10. 13
It has the function of displaying the calculation result numerically or writing it on a recording paper, and has the function of displaying the functional limit with a lamp or generating an alarm sound if necessary.

14 is a battery provided as a power source for the failure diagnosis device.

Next, the operation of this device will be described for the case where vibrations of the camshaft and tappet indicated by signal name B are detected.

In normal operation, the electrical signals obtained from the accelerometer 3 and amplifier 6 are as shown in Figure 2, and the shock vibration caused by the camshaft and tappet hitting each other is in the form of primary damping. appears in On the other hand, if deterioration phenomena such as looseness, dents, and wear occur,
The result is a random waveform as shown in FIG.

Reference electrical signal A that is not affected by aging of the injection pump
has a waveform as shown in FIG.

The signals B and A are extracted by P wave generators 7a and 74, respectively, and input to the signal shaper 8. The signal shaper 8 smoothes and rectifies the output signal of each filter in the order of the filters 7a, 7b, . . . , 7JL to obtain signals as shown in FIGS. 5 to 7.

The signal converter 9 has a peak voltage & as shown in FIG.

Convert the peak voltages B2...13s (or the peak voltages B4, B2'...B, / shown in Fig. 6) and the peak voltages AI, h...An shown in Fig. 7 into digital values. and input it to the arithmetic unit 10. The control device 11 controls the signal shaper 8, the signal converter 9, and the arithmetic device 10 so that their operations and signal exchange can be performed synchronously for each signal.

The arithmetic unit temporarily stores η peak voltage samples in the signal converter 9, which processes the peak voltage values as follows.

2. Calculate the frequency distribution of voltage vs. number of samples from the stored peak voltage. FIGS. 8 to 10 show examples of frequency distributions of the peak voltages shown in FIGS. 5 to 7, respectively.

3. Find the representative voltages of the A and B signals from the frequency distribution 0 The representative voltages are the voltages of the maximum number of samples of the frequency distribution as the representative voltages Af and Bff. Also, the maximum voltage of the frequency distribution is 1
00%, the voltage corresponding to 95chi is the representative voltage A
JL, BJ. BP is the effective value component of the voltage, B
J is the peak value component of the voltage. For example, in the case of a voltage that changes sinusoidally between +1.414 and -1,414, B, 9 is 1.0vXBJL is 1.414X0.95V
said Naru.

4. Perform the following calculation from the representative voltage.

f However, C indicates a proportionality coefficient for reducing the influence of invalid signals (noise) from the voltage signal.

5. Determine the degree of deterioration of the B signal for which diagnosis was performed from the correlation diagram (Fig. 11) between Rp, R1' and mechanical deterioration, which was determined in advance.

Then, the voltage ratio Rg or RJ is distinguished depending on the content of mechanical deterioration.

In the case of rattling, denting, wear, deterioration, or bending, the determination is made based on the voltage ratio Rt, and in the case of seizure or damage, the determination is made based on the voltage ratio RA.

The reason why Ry and RL are judged based on BJ and 131 is as follows.

This is the oscillating voltage that occurs when the injection pump is in operation, and when signs of failure begin to appear, Bf may change (increase), BJ alone, or both may change depending on the nature of the failure.

Performance deterioration during the normal aging process (i.e., the deterioration of the injection pump due to the above-mentioned jerkiness, pressure condensation, etc.) occurs when B2 increases first.0 In addition, abnormalities in some of the internal parts of the injection pump (such as sudden seizures, etc.) If symptoms) occur, BJ will increase rapidly.

Therefore, combining both Bp and BJ, the limit voltage ratio R
It is checked whether yS and EuS have been reached or not.

6. Output the results of the quantitative deterioration degree of the B signal subjected to the diagnosis to the display device 2 as a signal. In addition, the limit voltage ratio RJS, R before mechanical deterioration progresses and the function is lost.
A signal is also output to the display device when the result of the diagnosis is applicable to 'S.

A similar method is applied to the C, D, and E signals of the clothing to quantitatively evaluate deterioration and functional limits, and perform failure diagnosis.

The display device 12 receives the output of the arithmetic device 10 and displays the diagnosis result numerically or on a recording paper, and in the case of a functional limit,
Indications such as lamp lighting and alarm sound φ are performed.

Further, the calculation results by the calculation device 10 are stored in a recording device 13 having a reproducible storage function such as a magnetic medium or a paper tape.
is stored in

Next, in the case of an engine with multiple cylinders, there are as many injection pump parts as there are, and which pump part is determined can be determined by the position where the accelerometer is installed. In other words, by installing an accelerometer closest to the pump part to be diagnosed, diagnosis can be made because the vibration transfer function and mechanical impedance are different.

As described above, according to the present invention, the degree of deterioration of each part of the injection pump can be quantitatively known as the voltage ratio, and even a person without experience can easily and quickly determine a failure. can do.

Furthermore, if the injection pump has a plurality of pump parts, by providing a plurality of accelerometers, it is possible to easily determine which pump is malfunctioning.

Further, if the failure diagnosis device of the present invention is constantly used (if it is a vehicle system, it is mounted on the vehicle), it is useful for preventive maintenance against failures and losses can be minimized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the failure diagnosis device according to the present invention, FIGS. 2 to 7 are waveform diagrams showing examples of waveforms in the signal processing process of the embodiment, and FIGS.
FIG. 1 is a diagram illustrating the signal processing contents of the arithmetic device of this embodiment. 1... Injection pump, 3... Accelerometer, 7a-7I-
... Filter, 10 ... Arithmetic device, 12 ... Display device. Patent Application Hitachi Construction Machinery Co., Ltd. Agency Agency Lenth attorney Akimoto Affairs Agency Lenth attorney 1) Win -Fig. leather

Claims (1)

[Claims] A device for diagnosing failures by inspecting the function of a fuel injection pump in a diesel engine, which includes an gagometer that is adhesively fixed to the case of the fuel injection pump to detect vibrations, and an electric signal obtained from the acceleration side to detect fuel injection. A plurality of F-wave devices extract individual electrical signals corresponding to vibrations generated by each component of the pump, and a reference electrical signal that is not affected by aging of the fuel injection pump is extracted from the electrical signals. sampling the output signals of the P-wave device and each of these P-wave devices to determine a representative voltage value for each, and calculating a ratio between the representative voltage value of the individual electrical signal and the representative voltage value of the reference electrical signal 9; 1. A failure diagnosis device for a fuel injection pump, comprising a device and a display device that displays the calculation results.