A method for measuring the rotational speed of an electronically controlled diesel engine

Abstract

A kind of speed measurement method of electrically controlled diesel engine, the electrically controlled diesel engine includes diesel engine and generator connected with each other, during vehicle operation, the injector of diesel engine is monitored by open loop current sensor, the leakage magnetic portion of generator is monitored by magnetic flux leakage sensor, respectively obtain injection current signal and leakage current signal, injection current signal and leakage current signal are filtered by signal arrangement circuit Process, and the injection pulse signal and leakage pulse signal obtained are transmitted to single-chip microcomputer, single-chip microcomputer calculates the injection pulse signal and calculates the leakage pulse signal to calculate the injection calculated speed, and then the injection calculated speed and leakage calculated speed are weighted and fused by Kalman filtering fusion algorithm, so as to obtain the diesel engine speed to be measured, the present application is easy to operate, generator is used to measure diesel engine speed, applicable working condition is more, and measurement accuracy is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of speed measurement of electronically controlled diesel engine, and particularly relates to a speed measurement method of electronically controlled diesel engine. BACKGROUND

[0002] When testing a vehicle in a test field, many tests need to measure the speed of a diesel engine, and theoretically, the speed of the engine can be directly obtained through a CAN bus, but from the perspective of public credibility of testing, directly reading data from the original vehicle's own equipment can only be used for monitoring, and cannot be used for formal testing to issue a test report with legal effect, so a separate engine speed measurement device is needed.

[0003] In addition, during vehicle testing, it is also required that the device is easy to install and remove, does not require any special installation accessories, supports, etc., and is easy to adjust, and preferably can be automatically adjusted. However, the existing diesel engine speed measurement device needs to be installed with a complex fixing device, such as a sensor support in a narrow engine compartment, or even needs to drill holes in the engine to install the support, which is very cumbersome and does not meet the above requirements, resulting in that the speed measurement of the electronically controlled diesel engine is very inconvenient. SUMMARY

[0004] The purpose of the present application is to provide a speed measurement method of electronically controlled diesel engine, which simplifies the operation and improves the measurement accuracy.

[0005] The technical scheme adopted by the present application to solve the above technical problems is: a speed measurement method of electronically controlled diesel engine, the electronically controlled diesel engine comprising a diesel engine and a generator connected with each other, during vehicle operation, the fuel injector of the diesel engine is monitored by an open-loop current sensor, and the magnetic leakage part of the generator is monitored by a magnetic leakage sensor, to obtain a fuel injection current signal and a magnetic leakage current signal respectively, the fuel injection current signal and the magnetic leakage current signal are filtered by a signal conditioning circuit, and the obtained fuel injection pulse signal and magnetic leakage pulse signal are transmitted to a single-chip microcomputer.

[0006] The single-chip microcomputer calculates the time difference t between the durations of two adjacent fuel injection pulses according to the fuel injection pulse signal n , and judges whether a pulse of t n+1 >2t n appears in the 10 fuel injection pulses from the initial fuel injection pulse, n+1 when a pulse of t n >2t n+1 does not appear, the fuel injection calculation speed is calculated by a main injection frequency measurement method, and enters a pulse tracking state, and the subsequent speed is calculated at a frequency lock according to a pulse frequency change rate of not more than 50%, and when a pulse of t nWhen the pulse of t n+1 >2t n appears in the 10 fuel injection pulses from the initial fuel injection pulse, or when the pulse of t n+1 >2t n appears in the subsequent 10 fuel injection pulses in the pulse tracking state, the fuel injection calculated speed is calculated by using the main and auxiliary fuel injection frequency measurement method, and then the pulse tracking state is continued to judge whether the pulse of t n+1 >2t n appears in the subsequent 10 fuel injection pulses.

[0007] The main fuel injection frequency measurement method is that the 10 fuel injection pulses without the pulse of t n+1 >2t n are all divided into main injection pulses, then the time interval T between the start times of the adjacent two main injection pulses is calculated, and the fuel injection calculated speed n1=120 / T is calculated.

[0008] The main and auxiliary fuel injection frequency measurement method is that, among the pulses of t n+1 >2t n appearing in the 10 fuel injection pulses, the two fuel injection pulses related to the time difference of t n+1 are divided into the fuel injection pulses of the adjacent two work cycles respectively, then the fuel injection pulse with the maximum fuel injection time value in the adjacent two work cycles is divided into a main injection pulse, the time interval T between the start times of the adjacent two main injection pulses is calculated, and the fuel injection calculated speed n1=120 / T is calculated.

[0009] The single-chip microcomputer calculates the magnetic flux leakage frequency f according to the magnetic flux leakage pulse signal, and then calculates the magnetic flux leakage calculated speed n2=f*g, wherein g is a proportional coefficient of the magnetic flux leakage frequency.

[0010] The single-chip microcomputer performs weighted fusion on the fuel injection calculated speed n1 and the magnetic flux leakage calculated speed n2 by using a Kalman filtering fusion algorithm, so as to obtain the diesel engine speed to be measured.

[0011] When the open-loop current sensor does not monitor the fuel injection current signal, the single-chip microcomputer takes the magnetic flux leakage calculated speed n2 as the diesel engine speed to be measured.

[0012] Preferably, the open-loop current sensor is sleeved on the driving wire of the fuel injector, and the magnetic flux leakage sensor is attached to the surface of the magnetic flux leakage part of the generator.

[0013] According to the above technical scheme, the beneficial effects of the present application are:

[0014] The application is convenient to operate, only needs to pass the oil injector driving wire through the open loop current sensor, stick the magnetic flux leakage sensor on the magnetic flux leakage part of the generator by double-sided tape, and does not need any special installation accessories and supports, and the generator speed is introduced, so that when the engine speed is high due to the engine reverse traction, the oil nozzle does not spray oil, the generator can be used to measure the diesel engine speed, and the application is suitable for various working conditions and has high measurement accuracy. DETAILED DESCRIPTION

[0015] The embodiment provides a speed measurement method of an electronically controlled diesel engine, the electronically controlled diesel engine comprising a diesel engine and a generator connected with each other, an open loop current sensor is sleeved on a driving wire of an oil injector of the diesel engine, and a magnetic flux leakage sensor is pasted on the surface of a magnetic flux leakage part of the generator.

[0016] During vehicle operation, the oil injector of the diesel engine is monitored by the open loop current sensor, the magnetic flux leakage part of the generator is monitored by the magnetic flux leakage sensor, an oil injection current signal and a magnetic flux leakage current signal are obtained, the oil injection current signal and the magnetic flux leakage current signal are filtered by a signal processing circuit, and the obtained oil injection pulse signal and the magnetic flux leakage pulse signal are transmitted to a single-chip microcomputer.

[0017] The single-chip microcomputer calculates the time difference t between the durations of two adjacent oil injection pulses according to the oil injection pulse signal n , and judges whether a pulse t n+1 >2t n appears in the 10 oil injection pulses from the initial oil injection pulse. n+1 When the pulse t n >2t n+1 does not appear, the oil injection calculated speed is calculated by a main injection frequency measurement method, and the pulse tracking state is entered, the subsequent speed is calculated according to the pulse frequency change rate not greater than 50%, and the frequency is locked. n When the pulse t n+1 >2t n appears in the 10 oil injection pulses from the initial oil injection pulse, or the pulse t n+1 >2t n appears in the subsequent 10 oil injection pulses in the pulse tracking state, the oil injection calculated speed is calculated by a main and auxiliary injection frequency measurement method, and then the pulse tracking state is entered, and whether the pulse t n+1 >2t n appears in the subsequent 10 oil injection pulses is judged.

[0018] The main injection frequency measurement method is that the pulse t n+1 >2t nThe 10 injection pulses are divided into main injection pulses, the time interval between the start times of two adjacent main injection pulses is calculated as T seconds, and the injection measurement rotational speed n1 = 120 / T is calculated.

[0019] The main injection frequency measurement method is that, among the t n+1 >2t n pulses in the 10 injection pulses, the time difference between two injection pulses related to t n+1 is calculated, the two injection pulses are divided into two adjacent work cycles, and the injection pulse with the maximum injection time in the two adjacent work cycles is divided into a main injection pulse, the time interval between the start times of two adjacent main injection pulses is calculated as T seconds, and the injection measurement rotational speed n1 = 120 / T is calculated.

[0020] The t n+1 >2t n pulses in the subsequent 10 injection pulses are used as the judgment standard for the two frequency measurement methods, because when the t n+1 >2t n pulse appears, it means that the time difference between the n injection pulse and the previous injection pulse is significantly smaller than the time difference between the n injection pulse and the next injection pulse, which means that the main injection and the auxiliary injection occur at the same time, so all the injection pulses cannot be divided into main injection pulses, and it is necessary to distinguish different work cycles first, and then calculate and find the main injection pulse with the longest injection time in the work cycle containing multiple injection pulses according to the characteristic that the main injection of the diesel engine has a longer injection time than the auxiliary injection.

[0021] And t n+1 and t nThe difference between 2 times the coefficient is selected according to the reasonable calculation of the common parameter range of the electronically controlled diesel engine. Assuming that the minimum idle speed of the electronically controlled diesel engine is 500 rpm, about 8 r / s, the main injection frequency is 4 Hz, and the main injection interval time is 250 ms; assuming that the maximum speed of the electronically controlled diesel engine is 5000 rpm, about 80 r / s, the main injection frequency is 40 Hz, and the main injection interval time is 25 ms; assuming that the maximum acceleration capacity of the electronically controlled diesel engine is 1 s from 300 rpm to 3000 rpm, the speed change rate is about 72 r / s, and the main injection interval change rate is 225 ms / s; assuming that the electronically controlled diesel engine accelerates from 0 rpm to 5000 rpm as uniform acceleration, the number of turns required during acceleration is about 80 r, and the main injection interval change of adjacent two turns is 225 / 80*2=5.625 ms, thus the main injection interval change of the electronically controlled diesel engine at the minimum idle speed is 5.625 / 250=2.25%, and the main injection interval change of the electronically controlled diesel engine at the maximum speed is 5.625 / 25=22.5%. The main injection period Tm of the electronically controlled diesel engine usually corresponds to 1.5 turns of the crankshaft, about 540°, and the auxiliary injection period Tf usually corresponds to 0.5 turns of the crankshaft, about 180°, thus Tf / Tm=180 / 540=33%, and Tm / Tf=300%. Since the main injection interval change when accelerating to the maximum speed is about 22.5%, that is, Tm / Tf=(250%--300%), when accelerating, the ratio of the main injection interval and the auxiliary injection interval still has a change ratio of about 250%. In order to improve the recognition accuracy of the main injection and the auxiliary injection and prevent the auxiliary injection from being incorrectly recognized as the main injection, the value of 250% is further reduced to 200%.

[0022] The single-chip microcomputer calculates the magnetic flux leakage frequency f according to the magnetic flux leakage pulse signal, and then calculates the magnetic flux leakage measurement speed n2=f*g, where g is the proportional coefficient of the magnetic flux leakage frequency.

[0023] The single-chip microcomputer performs weighted fusion on the injection measurement speed n1 and the magnetic flux leakage measurement speed n2 through the Kalman filter fusion algorithm, so as to obtain the diesel engine speed to be measured.

[0024] When the open-loop current sensor does not monitor the injection current signal, it indicates that the injection nozzle no longer injects diesel oil, at this time the injection measurement speed n1 is 0, which is not the real speed of the diesel engine, but since the generator is connected with the diesel engine, the speed of the generator indirectly reflects the real speed of the diesel engine, therefore the single-chip microcomputer directly takes the magnetic flux leakage measurement speed n2 as the diesel engine speed to be measured, which is suitable for multiple working conditions and has high measurement accuracy.

Claims

1. A method of measuring the rotational speed of an electronically controlled diesel engine including a diesel engine and an electric generator connected to each other, characterized by: During the operation of the vehicle, the fuel injector of the diesel engine is monitored by an open-loop current sensor, and the magnetic flux leakage part of the generator is monitored by a magnetic flux leakage sensor, thereby obtaining a fuel injection current signal and a magnetic flux leakage current signal respectively; the fuel injection current signal and the magnetic flux leakage current signal are filtered by a signal conditioning circuit, and the obtained fuel injection pulse signal and magnetic flux leakage pulse signal are transmitted to a single-chip microcomputer; The single-chip microcomputer calculates the time difference t between the duration of two adjacent fuel injection pulses according to the fuel injection pulse signal n , and judges whether t n+1 >2t n appears in the 10 fuel injection pulses from the initial fuel injection pulse to the rear, when t n+1 >2t n does not appear, the fuel injection calculated speed is calculated by the main injection frequency measurement method, and the pulse tracking state is entered, the subsequent speed is calculated at a rate of no more than 50% of the pulse frequency change rate, and frequency locking is performed, when t n+1 >2t n does not appear in the subsequent 10 fuel injection pulses, the fuel injection calculated speed is continuously calculated by the main injection frequency measurement method; when t n+1 >2t n appears in the 10 fuel injection pulses from the initial fuel injection pulse to the rear, or t n+1 >2t n appears in the subsequent 10 fuel injection pulses in the pulse tracking state, the fuel injection calculated speed is calculated by the main and auxiliary injection frequency measurement method, and then the pulse tracking state is entered, and t n+1 >2t n is continuously judged whether t n+1 >2t n appears in the subsequent 10 fuel injection pulses; The main injection frequency measurement method is to divide the 10 injection pulses that do not appear t n+1 >2t n into main injection pulses, then calculate the time interval between the start times of two adjacent main injection pulses as T seconds, and calculate the injection measurement rotational speed n1=120 / T. The main and auxiliary injection frequency measurement method is to measure the frequency of injection within 10 injection pulses. n+1 >2t n In the pulse, with t n+1 The time difference is related to the two injection pulses, which are divided into two adjacent power cycles. Then, the pulse with the largest injection time value in the two adjacent power cycles is divided into the main injection pulse. The time interval between the start time of the two adjacent main injection pulses is calculated as T seconds, and the injection speed is calculated as n1=120 / T. The single-chip microcomputer calculates the magnetic flux leakage frequency f according to the magnetic flux leakage pulse signal, and then calculates the magnetic flux leakage measured rotational speed n2 = f * g, wherein g is a proportional coefficient of the magnetic flux leakage frequency; The single-chip microcomputer performs weighted fusion on the fuel injection measured rotational speed n1 and the magnetic flux leakage measured rotational speed n2 by a Kalman filtering fusion algorithm, thereby obtaining the diesel engine rotational speed to be measured; When the open-loop current sensor does not monitor the fuel injection current signal, the single-chip microcomputer takes the magnetic flux leakage measured rotational speed n2 as the diesel engine rotational speed to be measured.

2. A method of electronically controlling the measurement of the rotational speed of a diesel engine according to claim 1, characterized in that: The open-loop current sensor is sleeved on the driving wire of the fuel injector, and the magnetic flux leakage sensor is attached to the surface of the magnetic flux leakage part of the generator.