KR940006052B1 - Pressure detecting apparatus for a cylinder - Google Patents

Abstract

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Description

Internal pressure detection device of internal combustion engine

1 is a block diagram of an apparatus of the present invention.

2 is a block diagram of a conventional apparatus.

3A and 3B are cylinder pressure characteristics and respective output waveform diagrams according to the present invention.

4 is a pressure detection sequence diagram according to the present invention.

5 is a cylinder volume characteristic diagram.

6 is a map data characteristic diagram according to the present invention.

7 and 8 are flowcharts and time charts showing the urban average effective pressure calculation operation according to the present invention.

* Explanation of symbols for main parts of the drawings

1: engine 2: to

5: cylinder 6: to

9: pressure sensor 10: crank angle sensor

26: single chip microcomputer 27: A / D converter

28: memory 29: multiplexer

30: pressure measurement unit

The present invention relates to a cylinder internal pressure detection device for detecting a cylinder internal pressure of a multi-cylinder internal combustion engine.

The apparatus shown in FIG. 2 was common as an apparatus which detects the cylinder internal pressure of a multicylinder engine, and analyzes a characteristic. Reference numeral 1 denotes an engine having cylinders 2-5 of # 1 to # 4, 6-9 denotes a pressure counter for detecting the pressure of each cylinder 2-5, and 10 denotes a crank angle of the engine 1. To generate pulses and determine the pressure detection timing. 11 is an internal pressure measuring portion that receives the output of the pressure sensor 6-9 and the crank angle sensor 10 and measures the internal pressure. The interface converts the output of the pressure sensor 6-9 into a voltage value (I / F). A / D converters 17-20 and A / D for converting the outputs of the timing interface 16 and the interface 12-15 into which the output of the crank angle sensor 10 are inputted (12-15). Memory 21-24 and timing interface 16 and memory 21-24 that store the output of the D converter 17-20 and the output are simultaneously inputted, and the A / D converter 17-20 and the memory. An output to (21-24) is generated, and a data collection and analysis device 25 for controlling the number of data samples, measurement start and end, and analyzing measurement data is included.

The data collection and analysis device 25 is formed of, for example, a personal computer, and the cylinder pressure measurement portion 11 is generally commercially available.

In the above configuration, the pressure sensor 6-9 detects the pressure in the cylinders 2-5, and the crank angle sensor 10 generates unit angle pulses at predetermined intervals (e.g., 1 ° intervals in crank angle). The output of the pressure sensor 6-9 is input and stored in the memory 21-45 with the interface 12-15 and the A / D converter 17-20 interposed therebetween, and furthermore, the data acquisition and analysis device 25. The output of the crank angle sensor 10 is also input to the data collection and analysis device 25 with the timing interface 16 interposed therebetween. The data collection and analysis device 25 continuously collects data at predetermined crank angle intervals by the number of samples determined in the capacity range of the memory 21-24 by these inputs, and analyzes the data after the end of measurement, and P (θ) The engine characteristics such as pressure change of the curve (for each crank angle), PV curve (relationship between administrative volume and pressure), and Pi (urban average effective pressure) are summarized in the evaluation indexes.

However, since the conventional apparatus collects and stores pressure data continuously and organizes them into evaluation indicators to analyze the characteristics, the measurement is not possible in real time. For example, if the engine characteristics are detected and deteriorated during operation, the correction is improved. It cannot be used for engine control applications.

In addition, in order to understand engine performance, at least 30 cycles are required during the acceleration test to a certain number of combustion cycles, for example, at 6000 rpm at an idle state of 750 rpm, and the capacity of the memory 21-24 is 30 (cycles) × 720 (one-stroke crank angle of a four-cycle engine) x 1 byte (capacity to store pressure data roughly) = 21.6 kbytes, and when the pressure data was 2 bytes, the problem was that the pressure doubled and the memory capacity became large and the price was high. .

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is possible to measure the cylinder pressure measurement in real time, and to calculate the city average effective pressure of the engine, which can be applied to engine control and at the same time reduce the memory capacity. It is an object of the present invention to obtain a cylinder pressure detection device of an internal combustion engine that can be inexpensively made.

In order to achieve the object of the present invention, in the present invention, the internal pressure detection apparatus of an internal combustion engine sequentially outputs the output of each pressure detecting means for detecting the internal pressure of each cylinder at predetermined crank angles (e.g., 1 ° intervals of crank angle). An arithmetic storage means for arithmetic storage of a signal selection means for switching and selecting and a signal selection means output in accordance with the crank angle detection means output is provided.

Further, in the present invention, the cylinder pressure detection apparatus of the internal combustion engine includes signal selection means for sequentially switching and selecting each pressure detection means output for detecting the cylinder internal pressure of each cylinder for each combustion cycle, and crank angle detection of the signal selection means output. An arithmetic storage means for arithmetic storage in response to a means output is provided.

Since the pressure detection means output in the above invention is switched and selected and calculated and stored for each crank angle, each cylinder pressure is measured in real time for each combustion cycle and the memory capacity of the measurement result is also reduced.

In still another aspect of the present invention, the cylinder pressure detection device of an internal combustion engine is a volume or volume of a cylinder for a crank angle and a signal selection means for sequentially switching and selecting each pressure detection means output for detecting the cylinder internal pressure of each cylinder for each combustion cycle. A storage means for storing the change rate as a map and a calculation means for multiplying the signal selection means output and the map data for each crank angle signal generation, and adding the enemy for one continuous cycle to calculate the average urban effective pressure.

The pressure detection means output in the present invention is switched and selected for each combustion cycle, and the selected signal is multiplied by the crank angle signal generation and the map data of the volume or volume change rate of the cylinder stored in advance, and the number is added between one combustion cycle and the city average The effective pressure is calculated.

An embodiment of the present invention will be described below with reference to the drawings. 1 is a block diagram of a cylinder pressure detecting device according to an embodiment of the present invention, and reference numeral 26 denotes a single chip microcomputer having an A / D converter 27 and a memory 28, and 29 denotes an interface 12-15. It is a multiplexer which selects and switches, and the interface 12-16 and the multiplexer 29 have the cylinder pressure measuring part 30 comprised from the microcomputer 26. As shown in FIG.

In the above configuration, the output of the pressure sensor 6-9 is input to the multiplexer 29 with the interface 12-15 therebetween, where a signal is selected and input to the microcomputer 26. (A)-(d) of FIG. 3A (FIG. 3B in 2nd and 3rd embodiment), the pressure change of the cylinder 2-5 with respect to the crank angle of the engine of a 4 stoloke, and the waveform of each part are shown. The TDC represents the top dead center of the engine 1, and the BDC represents the bottom dead center of the engine 1.

The crank angle sensor 10 outputs a cylinder identification signal at 720 ° intervals as shown in (e) and (f) of FIG. 3a ((b) to (c) of FIG. 3b in the second and third embodiments). And at the same time output a crank angle signal with a 1 ° interval, and these signals are input to the microcomputer 26 with the timing interface 16. Accordingly, in the first embodiment, the pressure signal selected by the multiplexer 29 is As shown in Fig. 3a (g)-(j), the A / D crank 27 is A / D converted at 1 ° intervals of the crank angle in each cylinder, for example, 4 cylinders at 4 ° intervals for each cylinder stage. Memory 28. In the second and third embodiments, the pressure signal A / D converter 27 selected by the multiplexer 29 has a predetermined crank angle as shown in Fig. 3B (d). For example, A / D conversion is performed at 2 ° intervals and stored in the memory 28.

When the cylinder pressure is measured by such a sequence, the cylinder pressure information of the electric cylinder can be measured at 720 ° intervals. In the case where the number of cylinders is n, the interval for A / D conversion of the pressure resistance sensor output for each cylinder becomes n ° interval with the crank angle. However, the cylinder number n is preferably a divisor of 720.

As the cylinder pressure information collected by the microcomputer 26, parameters calculated for each measurement crank angle (1 ° in the first embodiment and 2 ° in the second and third embodiments), for example, crank angle θ and cylinder pressure Where P is a parameter calculated at the end of one combustion cycle measurement, e.g. Pi (shown average effective pressure), and the microcomputer 26 performs A / D conversion of the A / D granule 27 in the case of ①. After completion, the operation is performed and stored in the memory 28 sequentially. In the case of (2), the calculated value at the end of one combustion cycle measurement is calculated to be an evaluation index and the information is stored in the memory 28. The capacity of the memory 28 for storing information is the number of samples (e.g., 720 bytes) + alpha (temporary register for converting to each evaluation index), which is greatly reduced than before.

간격으로 통내압 정보를 계측할 수 있는 것은 명백하다.In the above embodiment, the angle detection accuracy of the crank angle sensor is 1 ° in the four-cylinder engine, but when the angle detection accuracy of the n-cylinder engine crank angle sensor is X °,

It is clear that the cylinder pressure information can be measured at intervals.

The sequences of the second and third embodiments are repeated at intervals of 720 degrees, as shown in Fig. 4A. That is, first, the pressure data of the cylinder 2 of # 1 is A / D converted from the intake to the one combustion cycle from the exhaust to the next, and data processing is performed between the crank angles of 180 degrees. Similarly, A / D conversion and data processing are performed at 720 ° intervals in the order of cylinders 4, 5, and 3 of # 3, # 4, and # 2. Therefore, data collection of each cylinder (2-5) is performed intermittently and sequentially at a rate of once every four times. When the number of cylinders is n, the measurement cycle for each cylinder is once every n times, and the crank angle interval to the next stroke is 720 ° / n.

4 (b) and 4 (c) show the output of the crank angle sensor 10 again.

Next, the calculation of the city average effective pressure Pi will be described. Simultaneous work Wi performed in one combustion cycle of the engine 1 is Wi = P.dV (kg.cm), P is cylinder pressure (kg / cm 2), and V is cylinder volume (cm 3). By dividing the urban work Wi by the stroke capacity Vh (cm 3), the city average effective pressure Pi = Wi / Vh (kg / cm 2) is obtained.

The expression that is actually used here

Becomes However, CA corresponds to crank angle θ, P _AD corresponds to A / D conversion value per crank angle signal generation (every 1 °) of output of pressure sensor 6-9, and M _CA corresponds to d c corresponding to crank angle θ. It is read from a map. That is, FIG. 5 shows the volume change with respect to the crank angle, and obtains the relationship between the volume change rate with respect to the crank angle shown in FIG. 6 in the relationship of FIG. The map data is read in correspondence with the crank angle.

7 and 8 show a flow chart art and a time chart art for calculating the city average effective value Pi. In step 100 at the start of measurement, the P ₁ counter is cleared and the map address is initialized. It is also synchronized to the intake TDC of the # 1 cylinder (2). Next, in step 101, as shown in Fig. 8B, the A / D conversion is started to detect the pressure. In step 102, map data is read out as shown in FIG. In step 103, it is determined whether or not the A / D conversion has been completed, and if so, multiplies the pressure data P _AD and the map data M _CA converted in A / D in step 104, and adds the enemy to the temporal register. Store in Temp. In step 105, the value of Temp is added to the P ₁ register and set as a new P _{1. In} step 106, it is determined whether the CA has reached 720 °, and the above-described loop is 1 ° of the crank angle. To 720 ° (1 combustion cycle) is repeated to calculate the city average effective pressure Pi and stored in the P ₁ register at step 107. The cylinder volume may also be stored as map data.

As described above, according to the first and second embodiments, since the pressure data of each cylinder is sequentially selected for each predetermined crank angle, the data is processed and the cylinder pressure can be measured in real time. By using it for air-fuel ratio control or ignition timing control, the engine characteristics can be improved. In addition, the memory capacity is small and can be made cheap.

According to the third embodiment, the city average effective pressure Pi is calculated for each crank angle signal generation, and the city average effective pressure Pi can be measured in real time, and the engine control for maximizing or uniformizing the Pi can be performed. In addition, the output of each pressure detection means is intermittently selected, and the memory capacity in the data processing can be reduced to reduce the cost.

Claims (3)

Each pressure detecting means for detecting the cylinder internal pressure of each cylinder, a crank angle detecting means for detecting a crank angle, signal selection means for sequentially switching and selecting the output of each pressure detecting means at predetermined crank angles, and the signal And an arithmetic storage means for arithmetic storing the selection means output in response to the crank angle detection means output. Pressure detection means for detecting the cylinder internal pressure of each cylinder, crank angle detection means for detecting a crank angle, signal selection means for sequentially switching the output of each pressure detection means for each combustion cycle, and selecting the signal. A cylinder internal pressure detection device for an internal combustion engine, comprising a calculation memory means for calculating and storing the output of the means in response to the crank angle detection means output. Each pressure detecting means for detecting the cylinder internal pressure of each cylinder, a crank angle detecting means for detecting the crank angle, a signal selecting means for sequentially switching the output of each pressure detecting means for each combustion cycle, and the crank angle Memory means for storing the cylinder volume or volume change rate as a map, and multiplying the signal selection means output with the map data for each crank angle signal generation, and adding the enemy for one combustion cycle to calculate the city average effective pressure. An internal pressure detection device for an internal combustion engine, comprising: a means.

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