CN105157914B - A kind of system and method in internal combustion engine cylinder pressure signal time domain gyration domain - Google Patents
A kind of system and method in internal combustion engine cylinder pressure signal time domain gyration domain Download PDFInfo
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Abstract
The invention discloses a kind of system and method in internal combustion engine cylinder pressure signal time domain gyration domain, cylinder pressure measuring device and pulse measure device, the corresponding pulse signal of cylinder pressure signal and flywheel ring gear of collection is sent to internal clock acquisition system by the cylinder pressure measuring device and pulse measure device, and the data of reception are further sent to processor and are processed by the internal clock acquisition system；The accurate zero crossing of pulse signal is determined by interpolation algorithm, conversion of the cylinder pressure signal by time domain to angle domain is realized on this basis；There is the problem of false triggering in effectively prevent conventional test methodologies because code device signal is lost or is interfered in the method, and effectively raises the reliability of data acquisition.
Description
Technical Field
The invention relates to a method for testing an in-cylinder pressure signal of an internal combustion engine, in particular to a system and a method for converting a time domain to an angle domain of the in-cylinder pressure signal of the internal combustion engine based on an interpolation algorithm.
Background
The in-cylinder pressure signal of the internal combustion engine contains rich information of the in-cylinder combustion process, and the information can provide important reference basis for the research and development and the performance improvement of the internal combustion engine. The internal combustion engine is operated in one working cycle every 720 degrees of crank angle, and the in-cylinder pressure signals are collected and analyzed based on the crank angle. Therefore, the existing in-cylinder pressure signal testing system mostly adopts an external clock sampling mode to test the in-cylinder pressure. The testing method needs to adopt an encoder to provide a trigger signal for controlling the testing system to acquire data according to a specific angle step. In use, the shell of the encoder needs to be connected to the engine body of the engine, and the rotating shaft of the encoder needs to be connected to the crankshaft of the engine. After the encoder is fixed, when the engine works, the crankshaft drives the encoder rotating shaft to rotate, and the encoder converts the rotation quantity of the crankshaft into a pulse signal through a photoelectric conversion principle and is used for triggering the acquisition system to acquire an in-cylinder pressure signal.
The method needs to find a proper position at the free end of the engine to fix the encoder, and the encoder is difficult to fix due to the fact that the existing engine has more free end parts and high integration level. The encoder rotating shaft and the crankshaft rotate synchronously, the concentricity of the encoder rotating shaft and the crankshaft is required to be high, if the centers of the encoder rotating shaft and the crankshaft have deviation, the problems that the output signal of the encoder is lost, even the encoder rotating shaft is broken and the like are easily caused, and the adverse effect is generated on the reliable work of the whole testing system. In addition, the output of the encoder is a high-frequency pulse signal, the signal is sent to a test system for shaping and then is used for triggering sampling, and multiple interferences such as a dynamometer exist in an engine experiment site, so that the test system is easy to sample by mistake.
According to the analysis of the existing in-cylinder pressure signal testing method, the existing method has the problems that the sensor is inconvenient to install, is easily influenced by interference and the like; and because the encoder is difficult to install, the method can only be applied to the occasions of laboratory tests at present, and for the vehicle engine, because the free end space of the engine is limited, the test of the pressure in the cylinder is difficult to realize.
Disclosure of Invention
In order to solve the defects in the prior art, the invention discloses a method for testing in-cylinder pressure signals by using an internal clock acquisition system and further converting acquired time domain signals into angle domain signals by an interpolation algorithm. The method does not adopt an encoder to trigger sampling, but installs a pulse signal test sensor at the flywheel end of the engine, and simultaneously acquires an in-cylinder pressure signal and a pulse signal through an internal clock acquisition system. After the acquisition is finished, the pulse signals are used as the reference to perform interpolation processing on the in-cylinder pressure signals, so that the conversion between time domain signals and angle domain signals is realized. The pulse signal sensor adopted by the method only needs to be arranged near the flywheel gear ring, the installation requirement is low, and the method is easy to realize; the internal clock sampling mode is adopted to collect signals, and the problem of abnormal sampling caused by the fact that the external clock sampling mode is easily triggered by an interference signal is solved.
In order to achieve the purpose, the invention adopts the following specific scheme:
a system for time domain to angle domain conversion of an in-cylinder pressure signal for an internal combustion engine, comprising: the device comprises a cylinder pressure measuring device and a pulse signal measuring device, wherein the cylinder pressure measuring device and the pulse signal measuring device transmit acquired in-cylinder pressure signals and pulse signals corresponding to a flywheel gear ring to an internal clock acquisition system, and the internal clock acquisition system further transmits received data to a processor for processing;
in the processor, a zero crossing point which is a point at which the output voltage of the pulse signal measuring device is zero is obtained through an interpolation algorithm, a time interval between two adjacent teeth is obtained according to data of the zero crossing point, and further data corresponding to any angle between the two teeth is obtained through the interpolation algorithm.
Further, the cylinder pressure measuring device comprises a cylinder pressure sensor which is installed on a cylinder cover of the engine and is connected to a combustion chamber of the engine through a pressure measuring channel.
Furthermore, the pulse signal measuring device is installed at the flywheel end of the engine, the distance between the front end of the pulse signal measuring device and the tooth crest of the flywheel gear ring is about 1mm, and when the engine works and each tooth of the flywheel gear ring passes through the sensor, the sensor is triggered to generate a pulse signal.
Furthermore, the pulse signal measuring device adopts a magnetoelectric sensor.
Furthermore, the internal clock acquisition system is a multi-channel high-speed data acquisition card working in an internal clock sampling mode, and the data transmission mode of the multi-channel high-speed data acquisition card adopts a USB interface or a PCI interface high-speed data transmission interface to communicate with the processor.
A method for time domain to angle domain conversion of an in-cylinder pressure signal of an internal combustion engine, comprising:
obtaining the zero point of the output voltage of the pulse signal measuring device, namely the time Tstart and Tend of the zero crossing point through an interpolation algorithm; the angle mark signal is the signal tested by the pulse signal measuring device;
the duration time corresponding to one tooth of the engine flywheel gear ring is between the two moments Tstart and Tend, and the angle corresponding to the two moments Tstart and Tend is the duration angle theta of one tooth;
according to the two moments of Tstart and Tend, the continuous angle theta of one tooth and the angle interval theta after converting the in-cylinder pressure signal from the time domain into the angle domainInterpolation intervalDetermining time step length T between adjacent points of in-cylinder pressure signal in angle domainstep；
According to the sampling interval TstepThe current tooth starting time Tstart and the angle deviation T between the first angle domain point obtained by the current tooth interpolation value and the current tooth starting time TstartoffObtaining the time T corresponding to the angle domainn，n＝0，1，２，３…；
According to the obtained angle domain corresponding time TnAnd n is 0,1,2,3 …, the value y of the in-cylinder pressure at each point converted into the angle domainnAnd n is 0,1,2 and 3 … obtained by linear interpolation of time-domain in-cylinder pressure signals measured before and after the point.
Further, when a zero-crossing point, which is a point at which the output voltage of the pulse signal measuring device is zero, is obtained by an interpolation algorithm, a Newton interpolation method is adopted for 3 times, and two points (x) before and after the zero-crossing point are obtained first0，y0)、(x1，y1)、(x2，y2) And (x)3，y3) Wherein x is0～x3The sampling sequence number of each sampling point is, because four points are continuous sampling points, the interval of adjacent points is different by 1 sampling point moment; and y is0～y3And then, the pulse signal sampling results of two points before and after the zero-crossing point are obtained, all x and y in the Newton interpolation formula are used in a reversed mode, and y is equal to zero, so that the corresponding x value is obtained.
Further, the angle θ corresponding to the two times Tstart and Tend: θ equals 360 ° CA/number of teeth of the flywheel ring gear.
Further, the interval time difference is Tstep：
In the formula, theta is the continuous angle of one tooth of the flywheel ring; thetaInterpolation intervalSetting the angle interval of two adjacent points converted into an angle domain; t isstartAnd TendIs zero-crossing point time data obtained by interpolation.
Further, the time T corresponding to each time in the angle domainnAn expression of (n ═ 0,1,2, 3.) is:
Tn＝Tstart+n×Tstep+Toff
in the formula, ToffThe angular deviation between the first angular domain point obtained for the interpolated value of the current tooth and the starting time Tstart of the current tooth.
The invention has the beneficial effects that:
1) the invention provides a novel method for installing a pulse signal sensor near a flywheel gear ring of an engine and acquiring in-cylinder pressure signals. The installation requirement of the pulse signal sensor is low, and the pulse signal sensor is easy to realize; the difficulty of fixing the encoder and the difficulty of ensuring the high concentricity of the rotating shaft of the encoder and the crankshaft when the encoder is adopted in the traditional cylinder pressure testing method are effectively solved.
2) The in-cylinder pressure signal testing method provided by the invention firstly collects in-cylinder pressure signals and pulse signals as analog signals by an internal clock collecting method, and then determines the accurate zero crossing point of the pulse signals by an interpolation algorithm, thereby realizing the conversion of the in-cylinder pressure signals from a time domain to an angle domain; the method effectively avoids the problem of false triggering caused by the loss or interference of the encoder signal in the traditional test method, and effectively improves the reliability of the data acquisition process.
Drawings
FIG. 1 is a diagram of the hardware configuration of the present invention;
FIG. 2(a) is a measured in-cylinder pressure signal versus pulse signal curve for 5 cycles;
FIG. 2(b) is a signal graph of the time domain in-cylinder pressure signal converted into the angle domain by the interpolation algorithm proposed by the present invention;
FIG. 3 is a schematic diagram of the zero crossing times of the pulse signal sensor resulting from the sampling process of the present invention;
FIG. 4 shows the time domain to angle domain principle of the in-cylinder pressure signal according to the present invention.
The specific implementation mode is as follows:
the invention is described in detail below with reference to the accompanying drawings:
the invention provides a novel method for testing in-cylinder pressure signals, which aims to solve the problems that an encoder is inconvenient to install, and sampling is easy to be abnormal due to loss of encoder signals or interference influence in the conventional in-cylinder pressure signal testing method. The method has the advantages of convenient sensor installation, reliable work and the like, can meet the requirements of pressure signal test and analysis in the cylinder of internal combustion engine research and development and production units, and has wide application prospect.
The invention provides a testing method and a testing system suitable for in-cylinder pressure signal acquisition, which comprise a hardware system and a testing and analyzing method.
1. Introduction of a hardware system: the hardware system comprises a sensor and an internal clock data acquisition system, wherein the sensor comprises a pressure sensor for testing the pressure signal in the cylinder and a pulse signal test sensor arranged near the flywheel gear ring. Wherein the cylinder pressure sensor is arranged on a cylinder cover of the engine and is connected to a combustion chamber of the engine through a pressure measuring channel, and the sensor outputs an analog signal. The pulse signal sensor is arranged opposite to the teeth of the flywheel gear ring, and when the engine works, each tooth of the flywheel gear ring passes through the sensor, the sensor is triggered to generate a pulse signal which is a time reference for converting the cylinder pressure signal from a time domain to an angle domain.
The method provided by the invention is based on finding the accurate time of the zero crossing point through an interpolation algorithm, which requires that a plurality of sampling points exist before and after the zero crossing point. The pulse signal sensor commonly used at present mainly comprises: the magneto-electric sensor, the Hall sensor and the photoelectric sensor output signals with only two levels, namely high and low levels, and the number of points before and after the zero crossing point is small, so that the use requirement cannot be met, and the magneto-electric sensor is the best choice for the method relatively speaking.
The internal clock acquisition system is a multi-channel high-speed data acquisition card working in an internal clock sampling mode, and the acquisition card triggers an analog-to-digital conversion unit by utilizing a self-contained clock signal to realize data acquisition. Because the method requires the acquisition card to have higher sampling speed, the data transmission mode of the acquisition card needs to adopt high-speed data transmission interfaces such as a USB interface or a PCI interface. Signals of a cylinder pressure sensor and a pulse signal sensor are sent to a high-speed data acquisition card, the signals are used as analog quantities to carry out data acquisition, and the acquired data are processed by the following method.
2. Introduction to test analysis methods: in order to convert the data sampled by the internal clock into data based on the crank angle, the following two steps are required: 1) obtaining a zero crossing point of the pulse signal sensor through an interpolation algorithm; 2) and converting the pressure signal in the cylinder in the time domain by adopting an interpolation algorithm based on the zero crossing point to obtain data based on the angle. The following is a description of the contents of each part:
1) acquisition of zero crossings
The zero crossing point is the point at which the output voltage of the pulse signal sensor is 0, and the time between two adjacent zero crossing points of the pulse signal is the duration of one tooth, and the time plays an important role in the time domain, namely the angle domain of the in-cylinder pressure signal. Because the acquisition process is to acquire once at certain intervals, the data of each zero crossing point of the pulse signal sensor cannot be completely acquired only through the data acquisition process. The accurate time of the zero crossing point is obtained through an interpolation algorithm by utilizing the values of sampling points before and after the zero crossing point. Fig. 3 is a schematic diagram of a pulse signal sensor obtained by a sampling process, in which the solid squares represent the sampled data and the circles represent the positions of the zero-crossing points.
The invention adopts interpolation to determine the position of the zero crossing point, adopts various interpolation algorithms such as Newton interpolation, Lagrange interpolation, Hermit interpolation and the like, adopts different orders for each method to compare, finds that the results obtained by different methods are similar, and explains the determination method of the zero crossing point by 3 times of Newton interpolation method. The 3-time Newton interpolation method needs to use two points before and after the zero-crossing point for calculation, and the four points are as follows: (x)0，y0)、(x1，y1)、(x2，y2) And (x)3，y3) Wherein x is0～x3The sampling sequence number of each sampling point is, because four points are continuous sampling points, the interval of adjacent points is different by 1 sampling point moment; and y is0～y3Then refers to the sampling results of two points before and after the zero crossing point, thus, x0～x3And y0～y3Are all known quantities.
The Newton interpolation equation is expressed as follows:
y＝Nn(x)＝f[x0]+f[x0,x1](x-x0) + one-pass interpolation
f[x0,x1,x2](x-x0) (x-x1) +. + quadratic interpolation
f[x0,x1,...xn](x-x0)(x-x1)...(x-xn-1)
Rn(x)＝f[x,x0,...,xn]·πn(x) Interpolation remainder
When determining zero-crossing points, it is actuallyyThe value is known, x is found, and for this purpose all x in the formula are calculated, in order to facilitate the use of an interpolation algorithm,yAll used upside down, thus resulting in 3 times the Newton interpolation algorithm as follows:
x＝Nn(y)
＝f(y0)+f[y0，y1](y-y0)+f[y0，y1，y2](y-y0)(y-y1)+
f[y0，y1，y2，y3](y-y0)(y-y1)(y-y2)
wherein,
in addition, for the zero-crossing point, y is 0, and thus:
in the above formula, x0＝f(y0) And (x)0,y0)，(x1,y1) 2 points before the zero crossing point; (x)2,y2)，(x3,y3) Two points after the zero crossing point, four points are adjacent sampling points, therefore, x0-x1＝x1-x2＝x2-x3The above formula can be written as:
x in the variables referred to in the above formula0Time of sampling point, y0～y3The time domain sampling point values of 4 adjacent pulse signals are all known quantities, and data of each zero crossing point can be obtained according to the formula. And obtaining the data of the zero crossing point, and obtaining the accurate time interval between two adjacent teeth.
2) Method for converting in-cylinder pressure time domain into angle domain
The precise time of the zero crossing point of the angle mark signal, namely Tstart and Tend shown in fig. 4, can be obtained through the interpolation algorithm, the duration time corresponding to one tooth of the flywheel gear ring of the engine is obtained between the two times, and the angle θ corresponding to the two times is 360 ° CA/tooth number of the flywheel gear ring. In the method, the hair is supposed to be sentThe rotating speeds of the motors in one tooth are the same, so that data corresponding to any angle between two teeth can be further obtained through an interpolation algorithm, as shown in fig. 4, a schematic diagram of time domain to angle domain of in-cylinder pressure signal is shown, and the implementation process is described by taking the diagram as an example. In the figure T0、T1、T2And T3I.e. with a phase difference of TstepData of each moment of time, TstepThe expression of (a) is as follows:
in the formula, theta is the angle between two adjacent teeth of the flywheel gear ring; thetaInterpolation intervalIs an angular interval that translates into an angular domain; t isstartAnd TendZero crossing point data obtained by interpolation; time T corresponding to each point converted into angle domainnThe expression of (n ═ 0,1,2,3 …) is:
Tn＝Tstart+n×Tstep+Toff
in the formula, ToffThe angular deviation between the first angular domain point obtained for the interpolated value of the current tooth and the start time Tstart of the current tooth, T for the calculation of the 1 st toothoffIs 0, T for tooth 2 in the figureoff＝T3-Tend。
Once the in-cylinder pressure at each time T after conversion into the angle domain is obtainedn(n is 0,1,2,3 …), the value y of each point of the in-cylinder pressure in the angular domainn(n-0, 1,2,3 …) passing through two time-domain in-cylinder pressure data (T) collected before and after the pointn is before，yn is before) And (T)n is after，yn is after) Linear interpolation is then performed, where Tn is beforeAnd Tn is afterThe difference between the sampling time of the front point and the sampling time of the rear point is 1, yn is beforeAnd yn is afterThe pressure value in the cylinder of the front point and the rear point is T1The time is taken as an example, and the in-cylinder pressure value corresponding to the time is y1The expression of (a) is as follows:
by adopting the method, the time domain data acquired by the internal clock acquisition card can be converted into the interpolation interval thetaInterpolation intervalAngular domain data of CA.
The time domain pressure signal in the current tooth can be converted into an angle domain by the method, and the method is adopted to process in each tooth.
According to the method, the time of a zero crossing point needs to be obtained by using an interpolation algorithm, corresponding points are needed before and after the zero crossing point to ensure that the interpolation process can be smoothly carried out, and the points are related to the adopted interpolation algorithm, the sampling frequency and the rotating speed of an engine. In the working process of the engine, the rotating speed change range is wide, the rotating speed is higher, the time of one cycle is shorter, the required sampling frequency is higher in order to ensure that the number of points required for interpolation is enough, the sampling frequency is ensured to be capable of obtaining enough sampling points only at high rotating speed, and no problem exists at low rotating speed.
According to the analysis, when the 3-time Newton interpolation method is adopted to calculate the zero crossing point, 2 sampling points are needed before and after the zero crossing point, so that at least more than 8 sampling points can be collected and 8 points are temporarily used for calculation within the duration of one tooth, and the sampling point number of one cycle of the engine is 8 × 2 × z and the rotating speed is n, assuming that the tooth number of the flywheel gear ring of the engine is z, the number of the sampling points of one cycle of the engine is 8 × 2 × z, and the rotating speed is n1Time of one cycle isAnd the sampling frequency at the current rotating speed is obtained as follows:
assuming that the number of engine teeth is 141 and the maximum operating speed is 2200r/min, the sampling frequency of the single channel obtained according to the above formula cannot be lower than 41.36 kHz.
When in-cylinder pressure signals are collected and analyzed, the number of sampling points is required, and for example, a diesel engine generally requires that the number of cycles of each sampling is more than 100; in the case of gasoline engines, the number of sampling cycles is 150 or more because the combustion cycle varies widely. The sampling frequency can be determined by the method, and when the rotating speeds of the engines are different, the corresponding time of each cycle is different, so the required sampling points are different, and the lower the rotating speed is, the longer the time of one cycle is, and the more the corresponding sampling points are. Analyzing the calculation method of the number of sampling points, and assuming that the rotating speed of the engine is n2And if the number of cycles needing to be sampled is m, the expression of the corresponding number of sampling points is as follows:
assuming that the number of engine teeth is 141, the maximum operating speed is 2200r/min, assuming that the idle speed is 600r/min, and data of 100 cycles needs to be collected, the number of sampling points required for each sampling at this time is: 827200 points.
When the method provided by the invention is actually applied, the sampling frequency and the number of sampling points are reasonably selected according to the number of flywheel teeth of an engine and the operating rotating speed range, and the in-cylinder pressure signal acquired by the internal clock can be converted into an angle domain signal according to the interpolation algorithm for subsequent analysis.
When the invention is applied, the attached figure 1 is a hardware structure schematic diagram of the testing method provided by the invention, the method needs to use a cylinder pressure sensor and a pulse signal sensor, and each signal is used as an analog signal and sent into an internal clock data acquisition system to realize data acquisition. Because the acquired data volume is large, the analog-to-digital conversion result is transmitted to a computer through a high-speed data transmission interface such as a USB or a PCI and the like, and subsequent analysis is carried out. The internal clock acquisition system performs data acquisition by using an internal self-contained clock, so that the time interval of each sampling point of the signal is fixed, namely the sampled signal takes time as a reference. The internal combustion engine works periodically by taking 720 degrees of crank angle as a cycle when working, and when analyzing the pressure signal in the cylinder of the internal combustion engine, the analysis needs to be carried out by taking the crank angle as a reference, so that the signal in a time domain needs to be converted into a signal in an angle domain, and the process is the main content related to the invention.
FIG. 2 is a comparison curve obtained by converting the measured in-cylinder pressure signal of the engine from the time domain to the angle domain by using the method. Wherein, fig. 2(a) is a comparison curve of the measured in-cylinder pressure signal and the pulse signal of 5 cycles, wherein, the abscissa is the number of sampling points, and the number of sampling points and the time are corresponding to each other because the sampling frequency of the internal clock is fixed. It can be seen from the figure that the sampling frequency is high, and the sampling points of the in-cylinder pressure signal and the pulse signal are more. FIG. 2(b) is a diagram showing the conversion of the time-domain in-cylinder pressure signal into an angle-domain signal by the interpolation algorithm proposed in the present invention, with the conversion being performed at an angular interval θInterpolation intervalSet at 0.5 ℃ A, 1440 points per cycle. As can be seen from comparison of the two graphs, the method provided by the invention can accurately convert the signals acquired by the internal clock into the angle domain.
Although the embodiments of the present invention have been described with reference to the accompanying drawings, it is not intended to limit the scope of the present invention, and it should be understood by those skilled in the art that various modifications and variations can be made without inventive efforts by those skilled in the art based on the technical solution of the present invention.
Claims (5)
1. A method for converting a time domain of an in-cylinder pressure signal of an internal combustion engine into an angle domain is characterized by comprising the following steps:
obtaining the points of 0 output voltage of the pulse signal measuring device, namely the moments Tstart and Tend of the zero crossing point through an interpolation algorithm;
the duration time corresponding to one tooth of the engine flywheel gear ring is between the two moments Tstart and Tend, and the angle corresponding to the two moments Tstart and Tend is the duration angle theta of one tooth;
according to Tstart and Tend, the continuous angle theta of one tooth andthe angular interval theta of the in-cylinder pressure signal after converting from time domain to angular domainInterval of differenceDetermining time step length T between adjacent points of in-cylinder pressure signal in angle domainstep；
According to the sampling interval TstepAnd the angle deviation T between the first angle domain point obtained by the interpolation value of the current tooth and the starting time Tstart of the current toothoffAnd obtaining the time T corresponding to the angle domain by the current tooth starting time Tstartn，n＝0,1,2,3…；
According to the obtained angle domain corresponding time TnN is 0,1,2,3 …, and the value y of the in-cylinder pressure at each pointnThe measured in-cylinder pressure signals at two points before and after each point are linearly interpolated, and n is 0,1,2,3 ….
2. The method according to claim 1, wherein when the output voltage of the pulse signal measuring device is 0, that is, the zero crossing point, is obtained by the interpolation algorithm, two points before and after the zero crossing point are obtained by the Newton interpolation method for 3 times, and (x) the time domain of the in-cylinder pressure signal is converted into the angle domain0，y0)、(x1，y1)、(x2，y2) And (x)3，y3) Wherein x is0～x3The sampling sequence number of each sampling point is, because four points are continuous sampling points, the interval of adjacent points is different by 1 sampling point moment; and y is0～y3Then the sampling results of two points before and after the zero crossing point are obtained, then all x and y in the Newton interpolation formula are used in a reversed mode, y is made equal to zero, and the corresponding x value is obtained.
3. The method of claim 1, wherein the angle θ between the times Tstart and Tend is the following angle θ: θ equals 360 ° CA/number of teeth of the flywheel ring gear.
4. The method of claim 1 wherein the time domain to angle domain of the in-cylinder pressure signal of the internal combustion engine,
interval time difference of Tstep：
In the formula, theta is a continuous angle of one tooth of the flywheel ring; thetaInterpolation intervalSetting an angle interval for converting into an angle domain; t isstartAnd TendIs zero crossing data obtained by interpolation.
5. The method of claim 4 wherein the time domain of the in-cylinder pressure signal of the internal combustion engine is converted to the angular domain at a time T corresponding to each point in the angular domainnThe expression of (a) is:
Tn＝Tstart+n×Tstep+Toff
wherein n is 0,1,2,3 …, ToffThe angular deviation between the first angular domain point obtained for the interpolated value of the current tooth and the starting time Tstart of the current tooth.
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| CN108644023A (en) * | 2018-04-25 | 2018-10-12 | 江苏大学 | Internal combustion engine cylinder pressure signal high frequency harmonic components characterizing method |
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| CN102003298A (en) * | 2010-11-26 | 2011-04-06 | 天津大学 | Real-time feedback device and method of combustion information for controlling engine |
| CN102072064A (en) * | 2010-12-13 | 2011-05-25 | 刘杨 | Engine fuel supply advance angle measuring system and measuring method |
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| CN110686892A (en) * | 2019-10-23 | 2020-01-14 | 中船动力有限公司 | On-line diesel engine elastic transmission gear state detection method |
| CN110686892B (en) * | 2019-10-23 | 2021-07-13 | 中船动力有限公司 | On-line diesel engine elastic transmission gear state detection method |
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| CN105157914A (en) | 2015-12-16 |
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