JPS601536A - Combusion-pressure detecting method for internal combustion engine - Google Patents

Abstract

PURPOSE:To detect pressure accurately, by correcting combustion pressure data by a correcting coefficient corresponding to the temperature data detected by a temperature sensor provided in a pressure sensor. CONSTITUTION:Combustion pressure data detected by a pressure sensor 4 and temperature data detected by a temperature sensor 6 provided in the sensor 4 are inputted in a processing device. A correcting coefficient corresponding to the temperature data detected by the sensor 6 is retrieved from tables wherein piezoelectric-element temperatures and correcting coefficients are written in advance in a memory device 11. The combustion pressure data of the sensor 4 is corrected by the correcting coefficient.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field 1] The present invention relates to a combustion pressure detection method for detecting the combustion pressure of a C internal combustion engine using a pressure sensor using a piezoelectric element.

[Prior Art] In an internal combustion engine that performs electronically controlled fuel injection control, ignition timing control, etc., combustion pressure may be detected as engine data for calculating a fuel injection whistle, optimum ignition timing, etc. Combustion pressure, which is the pressure inside the combustion chamber, is detected by attaching a pressure relief using a piezoelectric element to the wall of the combustion chamber of an internal combustion engine. Conventionally, humidity correction has not been performed on detected combustion pressure data, although the ratio between the output voltage and the applied strain force (pressure) varies considerably depending on the temperature of the element. Tena 6s.

Therefore, after a cold start, the humidity of the piezoelectric element of the pressure sensor changes depending on the operating state, and the piezoelectric constant changes, making it impossible to accurately detect combustion pressure.

[Object of the Invention] Therefore, the present invention focuses on the above points, and provides an internal combustion engine that can accurately detect the combustion pressure of the internal combustion engine using a pressure sensor using a piezoelectric element and a processing device that performs arithmetic processing on the detected data. The purpose of this paper is to provide a combustion pressure detection method.

[Configuration of the Invention] The configuration of the present invention to achieve the above object is as shown in chart 70-17-J of FIG. A method of detecting combustion pressure of an internal combustion engine using a device, the method processing combustion pressure data detected by a (P+, Pz) pressure sensor and detected temperature data from a humidity sensor installed in a pressure sensor. Load into the device (P3) Search for a correction coefficient corresponding to the temperature data from a table of piezoelectric element temperatures and correction coefficients written in advance in the storage device, and (P a ) confirm that the combustion pressure data can be corrected by the correction coefficient. The gist of this book is the combustion pressure detection method for internal combustion engines, which is characterized by its characteristics.

[Example] Embodiments of the present invention will be described below based on the drawings.

FIG. 2 shows a cross section of a main part of a spark-ignition internal combustion engine, which surrounds a combustion chamber 2 of a cylinder 1. A pressure sensor 4 using a piezoelectric element is attached to the cylinder head 3 so as to be able to detect combustion pressure. The pressure sensor 4 includes a pressure receiving plate at its tip, and a piezoelectric element 5 separated by a positive electrode plate and a negative electrode plate at a position where the pressure received by the pressure receiving plate is transmitted.
The piezoelectric element 5 receives the pressure horn transmitted from the pressure receiving plate, polarizes it, and induces an electric low. The piezoelectric element 5 is made of, for example, Jirun-bred titanium salt (PZT), and its rate of change in piezoelectric constant varies depending on the humidity of the element, as shown in FIG. Therefore, j using the piezoelectric element 5
The detection data of the J sensor 4 needs to be corrected according to the element temperature. Reference numeral 6 denotes a temperature sensor for detecting the temperature of the piezoelectric element groove 1 degree built into the pressure sensor 4, which is constituted by, for example, a thermistor, and outputs an analog voltage corresponding to 1 degree of the element 1In. 7 is a spark plug attached to the cylinder head 3, and 8 is an exhaust valve.

FIG. 4 shows a block diagram of an electronically controlled engine control device, and the micro combicoater portion in this control I device is a device 11 that performs correction processing of pressure saw data when detecting combustion pressure.

Reference numeral 10 denotes a cPU that performs fuel injection control, ignition timing control, etc. based on detected engine data according to a predetermined program, and also performs correction processing for the combustion pressure detected by the pressure sensor 4. Reference numeral 11 denotes a ROM, which is a read-only memory that stores the control program and ladder constants and table data necessary for the performance.As shown in Fig. 5, the correction coefficient corresponding to the element temperature of the pressure sensor 4 is Stored in a table format.

12 is a temporary memory RAM that can be read and read freely, and even after the engine key switch is turned to A,
In order to retain necessary data in the M12, it can also be a non-volatile memory that is constantly supplied with power directly from a battery. 13 is an input/output capo-1 which sequentially outputs the detection signals from each sensor outputting an analog signal;
An analog multiplexer 14 and an A/D converter 15 are connected.

The multiplexer 14 includes a pressure sensor 4, a temperature sensor 6,
The air flow meter 16 and water temperature sensor 1) 17 are connected, and the reading permission signal sent from the input/output port 13 allows
Analog detection signals sent from pressure sensor υ4, temperature sensor 6, etc. are selectively inputted by multiplexer 14, sent to A/D converter 15, converted to digital signals, and output from input/output port 13 to the input card V channel number. are attached and sequentially read into the CPU 10. 18 is a horn boat for digital signals, to which rotation speed sensor '19 etc. is connected.
Reference numeral 20 denotes an output boat from which a control drive signal corresponding to the optimum fuel injection amount and ignition timing determined from the engine data is outputted to the fuel injection valve 21, igniter 22, etc.

FIG. 6 shows a flowchart of a processing routine for correcting combustion pressure data sent from the pressure sensor 4 by the processing device, and a method for detecting combustion pressure will be explained based on this. When entering this processing routine, first, step 10
1 is executed, one of each analog signal input of the multiplexer 14 is selected by the signal from the input/output port 13, and one of the analog detection signals sent from each sensor υ group is A.
The signal is input to the /D converter 15 and converted into a digital signal. Next, in step 102, the input channel number assigned to each detection signal and its detection data are input and output.
-13 is read into the CPU10, and the process proceeds to step 103, where it is determined from the input channel number M whether the detected data read above is data indicating the piezoelectric element temperature from the temperature record 1 or not. Here, if the detection data read in step 102 is the temperature data of the piezoelectric element 5 of pressure sensor 1 no 4, then step 104 is executed and the RO
From the data table shown in FIG. 5 stored in M11,
After determining a correction coefficient corresponding to the temperature of the piezoelectric element and storing this correction coefficient in the RAM 12 in step 105, the process returns to step 101.

On the other hand, when it is determined in step 103 that the detection data read in step 102 is not the piezoelectric element temperature, the process proceeds to step 106 and checks whether this detection data is the combustion pressure data sent from the pressure sensor 4. Whether or not it is determined is determined from the input channel number. Here, when the read/υ detected data is not the combustion pressure, that is, the intake air amount data detected from the air flow meter 16 or the water humidity
If it is the water temperature data detected from step 7, then the process advances to step 109, and this detected data is stored in the RAM 12 as it is. However, when the read data is combustion pressure, step 107 is executed next, and this combustion pressure data is calculated in steps 104 and 105.
M12 is multiplied by the stored correction coefficient to correct the combustion pressure data according to the piezoelectric element temperature. And step 1
At step 08, the corrected combustion pressure data is stored in the RAM 12, and this processing routine ends. After that, step 1
01, the same process is repeated, and accurate combustion pressure data corrected each time is stored in the RAM'12, and the fuel injection is executed in another routine! l)J
In m control and ignition timing control routines, this accurate combustion pressure data is used as one of the engine data to indicate the engine status, along with engine speed data, throttle opening data, etc., and is used to determine appropriate fuel injection control and ignition timing. Control takes place.

Note that although the above embodiment was applied to a spark ignition internal combustion engine,
It can also be applied to correction processing of pressure data detected from compression ignition internal combustion (combustion pressure data used intermittently).

[Effects of the Invention] As explained above, in the combustion pressure detection method of the present invention, the combustion pressure data detected by the pressure sensor of the piezoelectric element as well as the detected temperature data from the temperature sensor provided in the pressure sensor are processed. A correction coefficient corresponding to the detected temperature data is retrieved from a table of piezoelectric element temperatures and correction coefficients that has been imported into the device and stored in advance, and the combustion pressure data is corrected using this correction coefficient. There is.

Therefore, according to the present invention, it is possible to correct changes in the piezoelectric constant due to element temperature fluctuations of the pressure sensor υ, and it is possible to always obtain accurate combustion pressure even if the temperature of the pressure sensor υ changes depending on the engine condition. is possible, and the combustion pressure is used as one of the engine data.
1'd), ignition R period flNI Ill'*t(7
) It is possible to improve l'iL by 1 degree.

[Brief explanation of the drawing]

FIG. 1 shows the configuration of the present invention, and FIGS. 2 to 6 show embodiments of the invention, FIG. 2 is a sectional view of the main parts of the internal combustion engine, and FIG. Figure 4 is a block diagram of the control processing device;
FIG. 6 is an explanatory diagram showing table data stored in the ROM 11, and FIG. 6 shows a correction calculation processing routine. 4... Pressure sensor 5... Piezoelectric element 6... Temperature sensor 10... CPU 11... ROM 12... RAM 13... Input/output capo-1- 14... Multiplexer 15...・A/D converter agent: Patent attorney Tsutomu Setatetsu and 1 other person Figure 1

Claims (1)

[Claims] A method for detecting the combustion pressure of an internal combustion engine using a pressure sensor and a processing device that performs arithmetic processing on the detected data using a pressure sensor, wherein the pressure sensor is detected by the pressure sensor→No. The combustion pressure data set in the pressure sensor 4 and the detected temperature data from the temperature sensor set in the pressure sensor 4 are taken into the processing device, and the piezoelectric element temperature and correction coefficient are stored in the memory device in advance. A combustion pressure detection method for an internal combustion engine, characterized in that a correction coefficient corresponding to detected temperature data is retrieved from a table, and the combustion pressure data is corrected based on the correction coefficient.