JP2653881B2 - In-cylinder pressure detection device for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-cylinder pressure detecting device for an internal combustion engine that detects an in-cylinder pressure of a multi-cylinder internal combustion engine.

[Conventional technology]

FIG. 2 shows a general device for detecting the in-cylinder pressure of a multi-cylinder engine and analyzing its characteristics. 1
Is an engine having cylinders 2 to 5 of # 1 to # 4, 6 to 9 are pressure sensors for detecting the pressures of the cylinders 2 to 5, and 10 generates a pulse corresponding to the crank angle of the engine 1 to detect pressure. This is a crank angle sensor for determining the timing of. Reference numeral 11 denotes an in-cylinder pressure measuring unit which receives the outputs of the pressure sensors 6 to 9 and the crank angle sensor 10 and measures the in-cylinder pressure.
Interface (I / F) 12 that converts the output of 9 to a voltage value
, The timing interface 16 to which the output of the crank angle sensor 10 is input, the A / D converters 17 to 20 for converting the outputs of the interfaces 12 to 15 into digital values, and the outputs of the A / D converters 17 to 20. The memories 21 to 24 and the outputs of the timing interface 16 and the memories 21 to 24 are input and the outputs to the A / D converters 17 to 20 and the memories 21 to 24 are generated. It has a data collection / analysis device 25 that controls the end and analyzes the measurement data. The data collection / analysis device 25 is formed by, for example, a personal computer, and the in-cylinder pressure measuring unit 11 is generally commercially available.

In the above configuration, the pressure sensors 6 to 9 detect the pressures of the cylinders 2 to 5, and the crank angle sensor 10 generates unit angle pulses at predetermined intervals (for example, at 1 ° intervals in crank angle). The output of pressure sensors 6-9 is interface 12-15 and A / D
The data is input to and stored in the memories 21 to 24 via the converters 17 to 20, is further input to the data collection / analysis device 25, and the output of the crank angle sensor 10 is also input to the data collection / analysis device 25 via the interface 16. . Based on these inputs, the data collection / analysis device 25 continuously collects data at predetermined crank angle intervals with the number of samples determined by the capacity range of the memories 21 to 24, analyzes the data after the measurement, and
(Θ) The pressure index of the diagram (for each crank angle), PV diagram (correlation between stroke volume and pressure), Pi (illustrated average effective pressure), and other evaluation indexes indicating the characteristics of the engine are arranged.

[Problems to be solved by the invention]

However, in the above-described conventional apparatus, pressure data is continuously collected and stored, and then the characteristics are analyzed by organizing them into evaluation indices. Therefore, measurement in real time is essentially impossible, For example, it cannot be used for an engine control application that detects engine characteristics during operation and corrects and improves if the characteristics deteriorate. Also, in order to grasp the engine performance, a certain number of combustion cycles,
For example, during an acceleration test from an idle state of 750 rpm to 6000 rpm, at least 30 cycles are required, and memory 21 to 24
Capacity is 30 (cycles) x 720 (crank angle of one stroke of a 4-cycle engine) x 1 byte (capacity for storing pressure data as a whole) = 21.6 Kbytes, and the pressure data is 2by
There is a problem that the memory capacity is increased and the cost is increased due to te.

The present invention has been made in order to solve the above-described problems, and can measure the in-cylinder pressure in real time, and can be applied to engine control, while reducing the memory capacity. It is an object of the present invention to provide an in-cylinder pressure detecting device for an internal combustion engine that can be manufactured at a low cost and that can process in-cylinder pressure in all steps in a combustion cycle.

[Means for solving the problem]

An in-cylinder pressure detecting device for an internal combustion engine according to the present invention includes a pressure detecting means for detecting an in-cylinder pressure of each cylinder, a crank angle, a unit angle pulse for each predetermined crank angle detection, and a crank angle of 720 °. Crank angle detection means for outputting a cylinder identification signal for each degree detection, and signal selection means for selecting an output of the pressure detection means for detecting an in-cylinder pressure of a cylinder identified by the cylinder identification signal over a combustion cycle section. And the cylinder pressure, which is the output of the signal selection means, is input over the combustion cycle section, and after calculating a parameter for obtaining an evaluation index indicating the characteristics of the internal combustion engine together with the cylinder pressure and the crank angle, storing the parameters; During the period up to the start timing of the combustion cycle of the cylinder identified by the next cylinder identification signal, the stored parameters are evaluated to indicate the characteristics of the internal combustion engine. It is provided with a arithmetic memory means for converting the mark.

[Action]

Since the output of the pressure detecting means in the present invention is switched and selected for each combustion cycle and is calculated and stored, the pressure of each cylinder is measured in real time for each combustion cycle, and the memory capacity of the measurement result is reduced. Furthermore,
Since the in-cylinder pressure in one combustion cycle of the selected cylinder is continuously measured, it is possible to process the in-cylinder pressure in the entire stroke from intake to exhaust.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration of an in-cylinder pressure detecting device according to this embodiment,
26 is a single-chip microcomputer having an A / D converter 27 and a memory 28, 29 is a multiplexer for selecting and switching the output of the interfaces 12 to 15, and the in-cylinder pressure measuring unit 30 is controlled by the interfaces 12 to 16, the multiplexer 29 and the microcomputer 26. Be composed.

In the above configuration, the outputs of the pressure sensors 6 to 9 are input to the multiplexer 29 via the interfaces 12 to 15,
Here, a signal is selected and input to the microcomputer 26. Third
FIGS. 7A to 7D show pressure changes of the cylinders 2 to 5 with respect to the crank angle of the four-stroke cycle engine and waveforms of various parts, where TDC indicates the top dead center of the engine 1 and BDC indicates the bottom dead center of the engine 1. . The crank angle sensor 10 is shown in FIG.
As shown in (c), the cylinder identification signals are output at intervals of 720 °, and the crank angle signals are output at intervals of 1 °. These signals are input to the microcomputer 26 via the interface 16. In response to this, the pressure signal selected by the multiplexer 29 is converted by the A / D converter 27 at a predetermined crank angle, for example, at intervals of 2 °, as shown in FIG.
A / D conversion is performed and the result is stored in the memory 28. Such a sequence is repeated at 720 ° intervals, as shown in FIG. 4 (a). That is, first, the pressure data of the cylinder 2 of # 1 is A / D converted in one combustion cycle from intake to exhaust, and
Data processing is performed between 80 ° crank angles. 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 for each of the cylinders 2 to 5 is performed intermittently 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. The in-cylinder pressure information collected by the microcomputer 26 includes parameters calculated for each measured crank angle (in this case, 2 °), for example, the crank angle is θ, the in-cylinder pressure is P, dP / dθ,
There are parameters calculated at the end of one combustion cycle measurement, for example, Pi (illustrated average effective pressure). In the case of the microcomputer 26, the calculation is performed after the A / D conversion of the A / D converter 27 is completed, and stored in the memory 28. I do. In the case of, the information is calculated in the period up to the start timing of the next cylinder as described above, and is converted into an evaluation index. The capacity of the memory 28 for storing information is the number of cylinders × the number of samples (for example, 4 × 720 = 2
880 bytes) + α (temporary register for converting into each evaluation index), which is greatly reduced from the conventional one.
FIGS. 4 (b) and 4 (c) show the output of the crank angle sensor 10 again.

〔The invention's effect〕

As described above, according to the present invention, since the pressure data of each cylinder is sequentially switched and selected for each combustion cycle and the data processing is performed, the pressure of each cylinder can be measured in real time. Is used for controlling the air-twist ratio and ignition timing of the engine, thereby improving the engine characteristics. In addition, the memory capacity can be small, the cost can be reduced, and the cylinder pressure in one combustion cycle of the selected cylinder is continuously measured, so that the cylinder pressure in all strokes can be processed. Thus, there is an effect that almost all information of the combustion index of the internal combustion engine can be calculated.

[Brief description of the drawings]

FIG. 1 is a block diagram of the apparatus of the present invention, FIG. 2 is a block diagram of a conventional apparatus, FIG. 3 is a diagram of in-cylinder pressure characteristics and output waveforms of various parts according to the present invention, and FIG. It is. 1 ... Engine, 2-5 ... Cylinder, 6-9 ... Pressure sensor, 10 ... Crank angle sensor, 26 ... Single chip microcomputer, 27 ... A / D converter, 28 ... Memory, 29 ...
Multiplexer, 30 ... In-cylinder pressure measurement unit. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A pressure detecting means for detecting an in-cylinder pressure of each cylinder, a crank angle is detected, a unit angle pulse is generated each time a predetermined crank angle is detected, and a cylinder identification signal is generated each time a crank angle of 720 degrees is detected. Crank angle detection means for outputting, signal selection means for selecting the output of the pressure detection means for detecting the in-cylinder pressure of the cylinder identified by the cylinder identification signal over a combustion cycle section, and output of the signal selection means Is input over the combustion cycle section, and after calculating a parameter for obtaining an evaluation index indicating the characteristic of the internal combustion engine together with the in-cylinder pressure and the crank angle, the parameter is stored, and is identified by the next cylinder identification signal. Computing storage means for converting the stored parameters into an evaluation index indicating the characteristics of the internal combustion engine during a period until a combustion cycle start timing of the cylinder. Cylinder detecting device for an internal combustion engine, characterized in that there was e.