CN105844250A

CN105844250A - Method for identifying maximum pressure rising rate based on vibration acceleration signal

Info

Publication number: CN105844250A
Application number: CN201610195062.1A
Authority: CN
Inventors: 程勇; 赵秀亮
Original assignee: Shandong University
Current assignee: Shandong University
Priority date: 2016-03-31
Filing date: 2016-03-31
Publication date: 2016-08-10
Anticipated expiration: 2036-03-31
Also published as: CN105844250B

Abstract

The invention discloses a method for identifying a maximum pressure rising rate based on a vibration acceleration signal. The method comprises the steps of 1, filtering out the high-frequency interference in the vibration acceleration signal by means of a Chebyshev low-pass filter; 2, filtering out the low-frequency interference in the vibration acceleration signal based on the empirical mode decomposition algorithm; 3, representing the maximum pressure rising rate through the area of a processing curve from a combustion initial moment to the occurrence moment of the maximum pressure rising rate. According to the technical scheme of the invention, the high-frequency interference in the actually measured vibration acceleration signal is filtered out by means of the low-pass filter. Meanwhile, the low-frequency interference in the vibration acceleration signal is filtered out based on the EMD method. Therefore, the signal-to-noise ratio of the measured signal is effectively improved. Moreover, the maximum pressure rising rate is represented through the area of the processing curve from the combustion initial moment to the occurrence moment of the maximum pressure rising rate. The above method establishes a linear relationship between the maximum pressure rising rate and the area of an IMF. Based on the linear relationship, the identifying result of the maximum pressure rising rate is corrected.

Description

A kind of method based on vibration acceleration signal identification maximum pressure rate of rise

Technical field

The present invention relates to signal processing technology field, particularly relate to a kind of based on vibration acceleration signal identification maximum pressure rate of rise Method.

Background technology

Maximum pressure rate of rise is as the key character parameter in Combustion Process Control, general by believing the acceleration of vibration of actual measurement Number it is integrated obtaining.Conventional time-domain integration method has trapezoid formula integration method and Simpson integration method, and trapezoid formula amasss Point-score algorithm is simple, and the required calculating time is shorter, but precision is poor, and convergence rate is slow；Simpson integration method relative to For trapezoid formula, calculate the highest, but pretreated vibration acceleration signal still suffers from interference, especially burn the beginning Near Dian, cause the initial value of integration to there is deviation, affect follow-up integrated value, and the computational efficiency of Simpson integration method is relatively Low.

Summary of the invention

The purpose of the present invention is contemplated to solve the problems referred to above, it is provided that a kind of based on the rising of vibration acceleration signal identification maximum pressure The method of rate, utilizes cylinder lid surface acceleration of vibration rate signal identification maximum pressure rate of rise, is removed real by low pass filter The High-frequency Interference of acceleration signals, utilizes EMD method to remove low-frequency disturbance therein, effectively raises measured signal Signal to noise ratio.

To achieve these goals, the present invention adopts the following technical scheme that

A kind of method based on vibration acceleration signal identification maximum pressure rate of rise, comprises the following steps:

Step one, utilizes chebyshev low-pass filter to filter the interference of vibration acceleration signal medium-high frequency；

Step 2, utilizes empirical mode decomposition (EMD) algorithm to remove the low-frequency disturbance in vibration acceleration signal；

Step 3, utilization processes the area going out in now from timing of combustion to maximum pressure rate of rise on curve and characterizes maximum pressure Rate of rise.

In described step one, chebyshev low-pass filter ripple factor is 0.001, and order is 10.

Described step one filters the high frequencies unrelated with burning exciter response signal more than 150 times of fundamental frequencies in vibration acceleration signal Interference.

Process curve in described step 3 is the dependency calculating each rank intrinsic mode function with cylinder pressure signal second derivative, Composition after front two rank intrinsic mode function summations is processed curve.

Beneficial effects of the present invention:

Removed the High-frequency Interference of actual measureed value of acceleration signal by low pass filter, utilize EMD method to remove low-frequency disturbance therein, Effectively raise the signal to noise ratio of measured signal.

The present invention utilizes and processes the area sign maximum pressure liter going out now from timing of combustion to maximum pressure rate of rise on curve High rate.

The present invention proposes the linear relationship between the maximum pressure rate of rise of foundation and IMF area, distinguishes it based on this linear relationship Know result to be modified.

The present invention, to utilizing the vibration signal research to in-cylinder combustion process feature parameter, evaluates in-cylinder combustion state, to internal combustion engine Combustion process on-line monitoring, closed loop control and fault diagnosis have important theory significance and practical value.

Accompanying drawing explanation

Fig. 1 is cylinder pressure, the rate of pressure rise and cylinder pressure second derivative curve；

Fig. 2 presses second derivative curve for processing curve with cylinder；

Fig. 3 (a) is 800r/min recognition result；Fig. 3 (b) is 1000r/min recognition result；

Fig. 3 (c) is 1200r/min recognition result；Fig. 3 (d) is 1400r/min recognition result.

Detailed description of the invention

The invention will be further described with embodiment below in conjunction with the accompanying drawings.

A kind of method based on vibration acceleration signal identification maximum pressure rate of rise, utilizes chebyshev low-pass filter to filter height Frequency interference, utilizes EMD empirical mode decomposition to remove the low-frequency disturbance in vibration acceleration signal, and utilization processes on curve from burning Initial point goes out the area in now to maximum pressure rate of rise and characterizes maximum pressure rate of rise.

Above-mentioned chebyshev low-pass filter ripple factor is 0.001, and order is 10, filters in vibration acceleration signal 150 times The High-frequency Interference unrelated with burning exciter response signal more than fundamental frequency.

Above-mentioned EMD is empirical mode decomposition (Empirical Mode Decomposition, EMD), and EMD is according to non-thread Signal decomposition is become one group of stable state and linear data sequence collection by property, the characteristic time scale of non-stationary signal itself, i.e. eigen mode Formula function (IMF).The internal feature of IMF reflection signal, residual components represents the trend of signal, need to meet following two condition: In whole signal, zero point number is equal with limit number or at most differs 1；For any point on signal, local maximum determine Envelope and the average of envelope that determines of local minimum be 0.It has the advantage identifying local feature.

Above-mentioned process curve is the dependency calculating each rank IMF with cylinder pressure signal second derivative, front two rank IMF and average cylinders Interior pressure signal second derivative dependency is higher, and composition after front two rank IMF summations is processed curve.

Fig. 1 shows cylinder pressure, rate of pressure rise curve and cylinder pressure signal second derivative curve, often by pressure liter in internal combustion engine High rate break in compression stroke is as timing of combustion, in cylinder pressure second derivative curve, and the before timing of combustion correspondence peak value One zero crossing, i.e. A point, what B was corresponding is that maximum pressure rate of rise goes out now.Fig. 2 shows that a cylinder circulated is intrinsic pressure Force signal second derivative and through EMD decompose after obtain IMF1 Yu IMF2 sum acceleration of vibration curve (be defined as process Curve), the circle of the first two is i.e. A, B in Fig. 12 point.Corresponding, process the first two triangle in curve Timing of combustion goes out now, maximum pressure rate of rise goes out now to be respectively used to sign.

Therefore the present invention utilizes the area going out in now from timing of combustion to maximum pressure rate of rise on acceleration of vibration curve, i.e. schemes Shaded area shown in 2 (being defined as IMF area) characterizes maximum pressure rate of rise.Fig. 3 (a)-Fig. 3 (d) gives different work Under condition, maximum pressure rate of rise and IMF area, for the ease of analyzing, give in figure simultaneously and utilize linear regression method off-line to build Linear relationship between vertical maximum pressure rate of rise and IMF area.As seen from the figure, under different operating modes, degree of fitting is respectively 0.97, 0.97,0.91,0.91, there is therebetween good linear relationship.Therefore in actual application, can add based on the vibration after processing Rate signal calculates corresponding IMF area, and in conjunction with the relation between the two under the different operating modes of off-line calibration, and then estimation is real Maximum pressure rate of rise under the operating mode of border.Wherein, 800r/min, 1000r/min, 1200r/min, 10N m and 1400r/min, The maximum deviation of 10N m operating mode is respectively 2.2%, 0.72%, 3.41% and 3.97%, shows that IMF area may be used for table Levy maximum pressure rate of rise.

Although the detailed description of the invention of the present invention is described by the above-mentioned accompanying drawing that combines, but not limit to scope System, one of ordinary skill in the art should be understood that on the basis of technical scheme, and those skilled in the art need not pay Go out various amendments or deformation that creative work can make still within protection scope of the present invention.

Claims

1. a method based on vibration acceleration signal identification maximum pressure rate of rise, is characterized in that, comprise the following steps:

Step 2, utilizes empirical mode decomposition algorithm to remove the low-frequency disturbance in vibration acceleration signal；

A kind of method based on vibration acceleration signal identification maximum pressure rate of rise, is characterized in that, In described step one, chebyshev low-pass filter ripple factor is 0.001, and order is 10.

A kind of method based on vibration acceleration signal identification maximum pressure rate of rise, is characterized in that, Described step one filters in vibration acceleration signal the high frequencies unrelated with burning exciter response signal more than 150 times of fundamental frequencies do Disturb.

A kind of method based on vibration acceleration signal identification maximum pressure rate of rise, is characterized in that, Process curve in described step 3 is the dependency calculating each rank intrinsic mode function with cylinder pressure signal second derivative, by front After two rank intrinsic mode function summations, composition processes curve.