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Method for detecting non-stable period circulating characteristics of internal-combustion engine

A technology with non-stationary period and cycle characteristics, applied in the direction of internal combustion engine testing, etc., can solve the problems of signal periodicity, high stability requirements, unsuitable for internal combustion engines, etc., and achieve the effect of reducing noise interference

Active Publication Date: 2014-07-16
MILITARY TRANSPORTATION UNIV PLA
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AI Technical Summary

Problems solved by technology

The above-mentioned patented technology is mainly aimed at detection methods of biomedical signals and mechanical equipment with strong periodicity and low noise.
The disadvantage of the above-mentioned prior art is that the requirements for signal periodicity and stability are too high, and it is not suitable for the detection of reciprocating mechanical signals such as internal combustion engines.

Method used

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  • Method for detecting non-stable period circulating characteristics of internal-combustion engine
  • Method for detecting non-stable period circulating characteristics of internal-combustion engine
  • Method for detecting non-stable period circulating characteristics of internal-combustion engine

Examples

Experimental program
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Effect test

example 1

[0022] Select two harmonic frequencies to modulate an exponentially decaying pulse to simulate the vibration and shock signal of the internal combustion engine. The expression of the simulation signal is: x(k)=exp(-at)(sin2πf 1 kT+sin2πf 2 kT)+n(t)

[0023] In the formula, k-is a natural number, T-sampling time interval, the value is 5×10 -5 , f m —Modulation frequency, the value is 100Hz, t-value is mod(kT, 1 / f m ), a-exponential frequency, the value is 800Hz, f 1 ,f 2 -carrier frequency, the values ​​are 3kHz and 7kHz respectively, n(t)-noise.

[0024] Such as Figure 1a Shown is the time-domain waveform of the simulated signal, Figure 1b Shown is the time-domain waveform of the simulated signal with noise added. Before adding noise, it can be seen that the signal contains multiple transient impact components. However, the transient components in the signal do not change strictly according to a certain period, but change according to the period of 0.0105s and 0.0095s...

Embodiment 2

[0029] Condition monitoring and fault diagnosis of combustion quality of HJ493 four-cylinder diesel engine.

[0030] The fault of abnormal combustion is realized by partially cutting off the oil in a certain cylinder.

[0031] A 601A01 ICP vibration sensor is installed on the cylinder head between the second and third cylinders of the diesel engine, and the QSY8104 external clamp type high-pressure oil pipe pressure sensor is clamped on the high-pressure oil pipe of the first cylinder of the diesel engine. The pulse signal is used to measure the speed and determine the top dead center signal of the first cylinder. The surface vibration signals of the cylinder head when each cylinder is partially cut off when the HJ493 diesel engine rotates at a speed of 700r / min. The sampling frequency is 12.8kHz, and the data sample length is 12288 data points. The vibration signal and the pressure signal of the high-pressure oil pipe are sent to the computer for analysis and storage through ...

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Abstract

The invention relates to a method for detecting non-stable period circulating characteristics of an internal-combustion engine. The method is characterized by comprising the following steps: arranging a vibration sensor and a first cylinder upper stopping point sensor on designated positions on the internal-combustion engine; synchronously acquiring vibration signals and first cylinder upper stopping point signals; performing subsection on the vibration signals by virtue of the first cylinder upper stopping point signals according to a working cycle, so as to acquire a plurality of isochronal data sequences with different lengths; performing equal angle re-sampling according to each working cycle by 720 degrees CA, and acquiring equal angle data sequences with the same length; performing wavelet transform on the equal angle data sequences so as to acquire angular frequency distribution of the signals; and performing the subsection on the angular frequency distribution according to an internal-combustion engine working sequence, and performing mapping enhancing on determined positions of polar coordinates in sequence, so as to stand out the non-stable period circulating characteristics. According to the method, the noise interference can be weakened, the non-stable period circulating characteristics in the signals can be stood out, and the internal-combustion engine state monitoring and fault diagnosing effects can be improved.

Description

technical field [0001] The invention belongs to an internal combustion engine signal analysis and detection method, in particular to an internal combustion engine non-stationary periodic cycle characteristic detection method that can be used for internal combustion engine state monitoring and fault diagnosis. Background technique [0002] The internal combustion engine is a commonly used power equipment and has been widely used in oil drilling, ships, automobiles, railways, agriculture, engineering construction, etc. As the "heart" of the mechanical system, its operating status directly affects the working status of the entire mechanical system. The internal combustion engine is subjected to complex alternating loads, including both rotating motion and reciprocating motion. Therefore, the signal of the internal combustion engine has the characteristics of non-stationary periodic cycle; in addition, the working environment is complex and the working conditions are harsh, and ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01M15/12
Inventor 贾继德张玲玲赵慧敏周斌肖云魁陈安宇乔龙
Owner MILITARY TRANSPORTATION UNIV PLA
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