Design of the most popular embedded diesel engine

Design of embedded diesel engine working condition monitoring device

Abstract: Aiming at the problem that the diesel engine fault diagnosis system can not comprehensively evaluate the working condition of the diesel engine, and can not predict and diagnose the fault, this paper proposes to use the principle of information fusion, use the instantaneous speed signal and the thermal parameters of the existing patrol monitoring and alarm system to realize the comprehensive diagnosis and trend analysis of the technical state of the power generation diesel engine. This paper introduces an embedded diesel engine working condition monitoring device based on TMS 320C 2407a. This device is the core part of the operation condition monitoring and fault diagnosis system of marine power generation diesel engine. It can realize the real-time monitoring and fault diagnosis of the working condition of marine power generation diesel engine. It can also be used as an independent monitoring and alarm device for locomotives, automobiles and other occasions

key words: t m s 320C 2407a; Diesel engine; Fault diagnosis; Monitoring

diesel engine fault diagnosis technology is a technology that understands and grasps the state of diesel engine in the process of use, determines whether its whole or part is normal or abnormal, finds faults and their causes early, and can predict the development trend of faults [1]. Taking the marine system as an example, the running state of modern marine power generation diesel engine is generally monitored by the engine room patrol monitoring and alarm system. However, the system cannot comprehensively evaluate the technical state of the diesel engine, let alone predict and diagnose the fault

1 function and principle of monitoring device

Figure 1 is the hardware diagram of a marine power generation diesel engine operation status monitoring and fault diagnosis system (the left side of the dotted line in the figure is the engine room, and the right side is the centralized control room). The system uses the principle of information fusion, the instantaneous speed signal and the thermal parameters of the existing patrol monitoring and alarm system, and can realize the comprehensive diagnosis and trend analysis of the technical state of the power generation diesel engine. The operation condition monitoring and fault diagnosis system of marine power generation diesel engine mainly includes: 1) magnetoelectric speed sensor, which picks up the instantaneous speed signal of power generation diesel engine; 2) The embedded diesel engine working condition monitoring device collects the instantaneous speed signal (or thermal parameter signal) for signal processing, carries out on-site data diagnosis, and transmits the diagnostic data to the upper computer system through the fieldbus; 3) The signal interface device collects the existing thermal parameters of the ship power station system and completes the isolation from the system; 4) Embedded monitoring and diagnosis device is a data processing and fault diagnosis expert system based on embedded industrial microcomputer, which completes the functions of data management and fault diagnosis

Figure 1 Hardware principle block diagram of monitoring and fault diagnosis system

embedded diesel engine working condition monitoring device is the core of marine power generation diesel engine fault diagnosis and condition monitoring system. The speed, temperature, pressure and other parameters of the diesel engine can be amplified and filtered, and then output and collected, and the data can be transmitted to the embedded microcomputer system through the fieldbus. It is a small expert system based on TMS 320C 2407a digital signal processor (DSP) for field acquisition and data processing. DSP integrates the real-time processing ability and the peripheral functions of the controller, providing an ideal solution for the application of the control system [2]. Its main function: through the collection of the instantaneous speed and thermal parameters (power, exhaust temperature, boost pressure, lubricating oil inlet and outlet temperature and pressure, air inlet temperature, main bearing temperature, fresh water inlet and outlet temperature, seawater temperature, etc.) of the on-site diesel engine, its own small expert system can diagnose whether there is a fault in the state of the diesel engine

diagnosis principle of the device: DSP collects the instantaneous speed signal data of diesel engine at a fixed frequency, and calculates the data by tooth average, digital filtering and whole cycle average. The instantaneous speed data is obtained for fast Fourier transform, and the frequency domain related eigenvalue is obtained. DSP combined with thermal parameters, the results are obtained by expert system

2 hardware design of monitoring device

the hardware composition principle of the device is shown in Figure 2. The thermal parameters in the figure as auxiliary analysis can be converted by the a/d module of DSP through the signal conditioning module. The instantaneous speed is obtained by the magnetoelectric sensor installed at the flywheel, and the top dead center of ignition is obtained by the pressure sensor on the oil pipeline through the charge amplifier. Device workflow: 1) the a/d module of DSP collects thermal parameters; 2) The a/d module of DSP combines its clock manager to reference the oil pressure trigger signal to collect the instantaneous speed at a fixed frequency; 3) The instantaneous speed is processed by DSP, and combined with the auxiliary thermal parameters, the internal expert system of DSP diagnoses and analyzes whether there is a fault in the diesel engine. If there is a fault, the expert system lists all possible faults, analyzes their causes, and determines the treatment plan; 4) Through the can module of DSP, the fault data and the scheme analyzed by the expert system are uploaded to the upper computer for data storage and future analysis. DSP expands SRAM, which makes it possible for DSP to process a large amount of real-time data and save on-chip in a short time

Figure 2 the technical complexity of the original ABS production of the hardware of the monitoring device and the investment in the ABS Project are the largest project management block diagram of the aluminum processing industry

3 program design

the program design of the monitoring device can be divided into four parts: 1) thermal parameter acquisition; 2) Instantaneous speed extraction; 3) Expert system analysis; 4) Upload experimental data. The realization methods of each part are:

1) adjust the signal to the appropriate amplitude range of the a/d conversion module, and use the a/d conversion module of DSP to realize the collection of thermal parameters

2) using the a/d conversion of DSP and the timer function, the instantaneous speed signal of diesel engine can be collected at a certain frequency. The process is: (1) set bit 8 or 7 general timer of global general timer control register gptcona; (2) Start analog-to-digital conversion event (t1toadc) starts analog-to-digital conversion by the cycle interrupt flag; (3) Set the cycle register of the timer. The specific size should be determined by the external clock source of DSP and the value of internal phase-locked loop; (4) Set the timer control register, determine that the counting mode is continuous increase, and adjust the desired calibration coefficient of the input clock and the clock source (the system adopts the internal CPU clock); (5) Clear the counter and mask the interrupt of the event manager; (6) Reset ADC module, set the number of conversion channels and sequencer order, and prohibit ADC conversion end interrupt

the specific code is

void adinit (void)

{

* gptcona = 0x0100;

* t1pr = 0x018f;

* t1con = 0x100c;

* t1cnt = 0x 0000;

* evaimra = 0x0000;

* evaifra = 0xFFFF;

* adctrl1 = 0x4000;

*max_conv = 0x0001;

* chselse1 = 0x3221;

* adctrl1 = 0x0000;

* adctrl2= 0x4300;

}

after the DSP initialization setting of constant frequency acquisition is completed, the acquisition results can be obtained by starting the timer and querying the PS9 bit status of adctrl2

3) expert system is composed of five modules: reasoning system, interpretation system, knowledge acquisition system, database and knowledge base [3]. Here, the database refers to the processed collected data (instantaneous speed frequency domain parameter values and thermal parameters), and the knowledge base is the judgment condition solidified in DSP

dsp can realize the fault analysis of diesel engine by using its own knowledge base through the processing data in the database. Of course, the knowledge base is built on a large number of experiments and experience. The workflow of the expert system is shown in Figure 3. DSP system is a small processing system, and its on-chip resources are far less complete than the system microcomputer. Therefore, it can only complete some functions of the expert system. The whole expert system should be realized by combining with the upper computer. For example, when measuring the burst pressure of each cylinder, the auxiliary machine is in normal operation. When reasoning, you can just call other parameters in front of the tension machine, which is a common equipment in the instrument industry; The data measured during maintenance needs to call the data of historical database for comprehensive diagnosis. At this time, DSP alone can't do anything, so the reasoning system is carried out by the upper computer. The knowledge base acquisition system must also be achieved by upgrading the diagnostic program of DSP after obtaining new knowledge through the host computer on the basis of saving a large number of experimental data and experience

Figure 3 work flow chart of expert system

4) data upload mainly realizes the data exchange between DSP and upper computer. For specific implementation, please refer to the relevant data of CAN bus [4]

4 conclusion

this set of embedded diesel engine working state monitoring device can use its own expert system to independently diagnose the working state of diesel engine in real time, and upload the data to the upper diagnosis system through its can bus interface, reducing the work of the upper system [5]. If the monitoring device is equipped with a display module, it can also be used as an independent monitoring and alarm device for locomotives and automobiles to help you further understand the equipment vehicle and other occasions

references

[1] Huang Hailiang, Miao min, Yu Fangping Monitoring and fault diagnosis system of marine power generation diesel engine [j] China navigation, 2003, 6 (2):55 ~ 57

[2] Liu Heping, Yan Liping, Zhang Xuefeng, et al TMS 32lf240xdsp structure, principle and application [m] Beijing: Beijing University of Aeronautics and Astronautics Press, 2002

[3] Yu Fangping, Jin Xiaojun, Yang Jianguo, et al Remote condition monitoring and fault diagnosis system of marine internal combustion engine [j] Journal of Wuhan University of technology, 2000, 24 (6):619 ~ 621

[4] Wu Kuanming Can bus principle and application system design [m] Beijing: Beijing University of Aeronautics and Astronautics Press, 2001

[5] Yu Fangping, jinhuabiao, Chang Yong, et al Design of condition monitoring and fault diagnosis instrument for marine diesel engine [j] Journal of Wuhan University of technology, 2002, 26 (3):312 ~ 314 (end)