JPH02221647A - Control device of internal combustion engine - Google Patents

Abstract

PURPOSE:To correct an inter-solid difference and a change on standing and calculate a precise control quantity by comparing detection values of an oxygen sensor and an atmospheric pressure sensor to each other, and calculating the correction value of the detection value of oxygen sensor, when the detection value of the oxygen sensor fluctuates according to the atmospheric pressure. CONSTITUTION:The control factor of an internal combustion engine is controlled by a means A. In this case, oxygen partial pressure of a gas introduced to the internal combustion engine is detected by a sensor B, and the atmospheric pressure around the internal combustion engine is detected by a means C. The correcting condition of the sensor B the detection value of which fluctuates according to the atmospheric pressure is judged by a means D. Further, under the correcting condition of the sensor B, the detection value of the sensor B is compared with the detection value of the means C, whereby the correction value of the detection value of the sensor B is calculated by a means E. The output value of the sensor B is corrected by the portion of the correction value by a means F, and applied to the means A. Hence, the inter-solid difference and change on standing are corrected to calculate a precise control quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for an internal combustion engine having an oxygen partial pressure sensor disposed in an intake pipe of the internal combustion engine.

[Conventional technology]

The intake pipe of an internal combustion engine is made of a solid electrolyte, such as zirconia, which measures the oxygen partial pressure of the air-fuel mixture in the intake pipe, and uses the oxygen partial pressure to determine fuel injection amount and ignition timing, etc. of the fresh air introduced into the internal combustion engine. There are known devices that control factors (hereinafter simply referred to as control factors) that are controlled according to the amount of gas.

For example, see JP-A-63-195359. The oxygen sensor that controls the fuel injection amount and ignition timing based on the oxygen partial pressure value uses an air flow meter, similar to the so-called D-J system that uses intake pipe pressure, in that altitude compensation is not required in principle. This has advantages over the so-called LJ system. Furthermore, the DJ system has the advantage of being more accurate because it is controlled not by indirect factors such as intake pipe pressure but by more direct oxygen partial pressure.

[Problems to be Solved by the Invention] The principle of determining oxygen partial pressure using an oxygen sensor is to utilize the fact that the limiting current changes depending on the oxygen partial pressure. Here, the limiting current is the saturation current flowing through the solid electrolyte defined by the rate of oxygen molecule diffusion through the diffusion means. However, the limiting current value is regulated by the diffusion rate of oxygen molecules passing through the diffusion means, and the diffusion rate is controlled by the film thickness and pore size of the diffusion layer, and variations in these factors between products cannot be avoided. However, there is a problem in that individual lid opening occurs in the sensor output, causing deviations in the required fuel injection amount and ignition timing. The rate of diffusion is also affected by changes over time. That is, over many years of use, poisonous substances contained in the recirculated gas from the exhaust gas recirculation device or in the fuel separated from the canister tend to adhere to the surface or internal holes of the diffusion layer.

This invention corrects such individual opening and aging,
The purpose of this is to enable accurate calculation of control variables such as required fuel injection amount and ignition timing.

[Means to solve the problem]

As shown in FIG. 1, the internal combustion engine control device of the present invention includes a control means A for controlling control factors of the internal combustion engine, a control means A that is arranged in the intake pipe of the internal combustion engine, and controls the oxygen partial pressure of gas introduced into the engine. Sensor means B for detecting; Atmospheric pressure detecting means C1 for detecting the atmospheric pressure around the internal combustion engine; Oxygen sensor calibration condition determining means D1 for determining the calibration conditions of the oxygen sensor in which the detection value of the oxygen sensor B responds to atmospheric pressure; Under the calibration conditions B, means E calculates a calibration value of the detection value of the oxygen sensor by comparing the detection value of the oxygen sensor B with the detection value of the atmospheric pressure detection means C, and the output of the oxygen sensor B is equal to the calibration value. Means F are provided for applying a calibration value to the control means A.

[Effect]

The sensor means B detects the oxygen partial pressure, and the control means A controls the engine according to the oxygen partial pressure. Atmospheric pressure detection means C detects atmospheric pressure, and oxygen sensor calibration condition determination means determines conditions under which the output value of oxygen sensor B can detect atmospheric pressure. Under this condition, the oxygen sensor calibration value calculation means E
calculates the calibration factor for the oxygen sensor output value. The oxygen sensor value calibration means F calibrates the sensor output value according to the calibration value.

〔Example〕

In FIG. 2, 10 is a cylinder block, 12 is a piston, 14 is a connecting rod, 16 is a cylinder head, 18 is a combustion chamber, 20 is a spark plug, 22 is an intake valve, 2
4 is an intake boat, 26 is an exhaust valve.

28 is an exhaust boat, 29 is a canister, and 30 is a distributor. The intake boat 24 is connected to an air cleaner 40 via an intake pipe 31, a surge tank 32, a throttle valve 34, and an intake pipe 36. A fuel injector 42 is arranged in the intake pipe 3I close to the intake boat 24. An exhaust pipe 44 is connected adjacent to the exhaust boat 28 .

An exhaust gas recirculation passage (BGR passage) 45 is provided to connect the exhaust pipe 44 and the surge tank 32.

Exhaust gas recirculation control valve (EGR valve) 46 is connected to EGR passage 4
5. In this embodiment, the EGR valve 46 includes a negative pressure actuated diaphragm mechanism 47. The diaphragm mechanism 47 has a diaphragm 47-1, and the diaphragm 47
-r is connected to an EGR port 48 formed slightly upstream of the idle position of the throttle valve 34. The pressure regulating valve 49 has a diaphragm 49a, which is connected to an orifice 51 in the EGR passage 45 via a pressure conduit 50.
It is connected to a pressure chamber 52 formed downstream of. Pressure regulating valve 4
9 controls the negative pressure introduced from the EGR port 48 to the negative pressure operating mechanism 47 of the EGR valve 46 in accordance with the pressure in the pressure chamber 52. The diaphragm 49a of the pressure regulating valve 49 is E
It is connected to a negative pressure boat 53 slightly upstream of the GR boat 48, and negative pressure according to the engine load acts on the diaphragm 49a to counteract the recirculated exhaust gas pressure, and the pressure regulating valve 49
Applying a negative pressure that becomes stronger as the load increases, opposing the spring 49b. As a result, the EGR rate can be controlled to increase according to the load. Since the configuration and operation of the EGR device are well known per se, further explanation will be omitted.

The control circuit 54 is configured as a microcomputer system, and controls engine control factors such as fuel injection and ignition timing. The control circuit 54 is connected to each sensor for engine operation control, and receives signals according to engine operating conditions. Crank angle sensor 56.5
8 is provided in the distributor 30. The first crank angle sensor 56 is installed opposite the magnet piece 60 on the distributor shaft 29a, and
A pulse signal is generated every 20 degrees of rotation, that is, every cycle of the engine, and serves as a reference signal. The second crank angle sensor 58 is installed opposite to the magnet piece 62 on the distributor shaft 29a, and generates a pulse signal every 30 degrees of rotation of the crankshaft to determine the engine rotation speed. This signal also serves as a trigger signal for fuel injection and ignition timing control. The water temperature sensor 64 is located in the cylinder block 1
The temperature of the cooling water in the cooling water jacket 10a of No. 0 is detected.

A throttle valve opening sensor 66 is provided on the throttle valve 34, and a signal corresponding to the opening of the throttle valve 34 is obtained. An exhaust side oxygen sensor 68 is provided in the exhaust pipe 44. This exhaust side oxygen sensor 68 is for air-fuel ratio feedback control, and is not for controlling the air-fuel ratio to the stoichiometric air-fuel ratio.
A sensor that controls the air-fuel ratio to be leaner than the stoichiometric air-fuel ratio is a lean sensor. An intake side oxygen sensor 70 is provided in the surge tank 32. This intake side oxygen sensor 70 is provided to measure the oxygen partial pressure in the total gas introduced into the engine, and is so-called L-
It is provided in place of the air flow meter in the J system and the intake pipe pressure sensor in the D-J system (see Japanese Patent Laid-Open No. 19539/1983). The atmospheric pressure sensor 71 is a well-known device that outputs a signal according to atmospheric pressure (absolute pressure). The bellows expands and contracts according to the pressure in the atmospheric chamber, and the atmospheric pressure can be determined from the amount of expansion and contraction.

The intake side oxygen sensor 70 has a well-known structure including a solid electrolyte such as stabilized zirconia, a sensor electrode, a pump electrode, a porous diffusion layer, and a heater, so its detailed structure is not shown. The sensor control circuit 72 is of a normal type and has a function of controlling the current between the pump electrodes so that the voltage applied between the sensor electrodes is constant, and outputs a pump current proportional to the oxygen partial pressure of the gas to be detected. It can be extracted as The heater control circuit 73 controls the heater current built into the sensor 70 so that the temperature of the sensor reaches a predetermined activation temperature of 700°C.

The control circuit 54 is turned off when the ignition key switch 75 is turned off.
When turned on from F, it is connected to the power source 77 and starts operating, and the operating state of the control circuit 54 is maintained even when starting 206. When the ignition key switch is turned OFF, the operation of the control circuit 54 is stopped, but when the ignition key switch is turned OFF from ON, the control circuit 54 is activated due to the calibration process of the oxygen sensor 70 according to the present invention. Continue the state. For this reason, it includes an inverter 79 that detects when the ignition key switch is turned from ON to OFF, a timer 80 that starts operating when the inverter 79 is turned ON, and an AND gate 82. Ignition key switch 75 from ON to O
When turned FF, the timer 80 continues to energize the control circuit 54 for a while, for example, 20 minutes, and the control circuit 54 can continue to operate during this time.

Hereinafter, a control circuit 5 for controlling fuel injection and ignition timing to realize the engine control according to the present invention described above.
The operation of step 4 will be explained using a flowchart. Figure 3 shows a routine for calculating fuel injection amount and ignition timing,
This routine may be executed within the main routine or may be integrated with the routine of FIG. In step 100, the ignition key switch 75 is turned OFF.
Detection is made as to whether or not it has occurred. When the ignition key switch is ON, proceed to step 102 and count the counter C.
Clear TfME. This counter CTIME is for measuring the elapsed time after the ignition key switch 75 is turned from ON to OFF. In step 104, it is determined whether the oxygen sensor 70 is in an active state. If it is determined that it is inactive, step 1
Proceeding to 0B, the engine rotation speed NE calculated from the interval of pulse signals every 30 degrees of crank angle from the second crank angle sensor 58 and the data of the throttle valve opening TA detected by the throttle valve opening sensor 66 are input. be done. In step 108, the fuel injection amount TP, the ignition timing S
The map calculation process of A is generally shown. fuel injection f
In order to calculate iTP, there is a map TP (TA) that calculates the fuel injection amount TP from the engine speed NB and throttle valve opening TA, and this map is used from the current engine speed and throttle valve opening TA. and fuel injection amount T
P(TA) is calculated. Similarly, in order to calculate the ignition timing, there is a map 5A (TA) that calculates the ignition timing from the engine speed NE and the throttle valve opening TA. Ignition timing 5A (TA) is calculated using .

If it is determined in step 100 that the state is active, step 110
, the output current ■1 of the oxygen sensor 70 is read,
In step 112, the output correction coefficient K of the oxygen sensor 70 is
A v g is input, and in step 114, the corrected current value is calculated by 11=KAvt xH'. The sensor output value calibration routine in steps 112 and 114 will be described in detail later.

Step 116 is the fuel injection amount TP after the oxygen sensor is activated.
, generally shows the map calculation process of ignition timing SA. In order to calculate the fuel injection amount TP, the engine speed NE
There is a map TP (TI) that calculates the fuel injection amount TP from the current engine speed and the sensor current.
'(TI) is calculated. Similarly, in order to calculate the ignition timing, there is a map 5A (II) that calculates the ignition timing from the engine speed NE and the sensor current II. The ignition timing 5A (TI>) is calculated using this map.

FIG. 4 shows a crank interrupt routine that is executed every time a pulse signal of 30 degrees of crank angle arrives from the crank angle sensor 58. In step 130, it is determined whether the current crank angle is the crank angle at which fuel injection processing is to be executed. This determination can be made in a well-known manner based on the number of 30 degree pulse signals from the reference crank angle position detected by the first crank angle sensor 56. Step 1
At step 32, necessary correction processing is added to the fuel injection amount TPf1mal calculated at step 120 in FIG. A typical example of such correction is air-fuel ratio feedback correction using the first oxygen sensor 68. Step 134
Then, a fuel injection signal is formed so that the control circuit 54 applies a fuel injection signal to the injector 42 so that the corrected amount of fuel is injected.

In step 136, it is determined whether the current crank angle is the crank angle at which the ignition signal forming process is executed. This determination can be made based on the number of 30 degree pulse signals from the reference crank angle position detected by the first crank angle sensor 56, as described above. In step 138, necessary correction processing is added to the ignition timing SA"'°1 calculated in step 120 of FIG. 9. A typical example of such correction is ignition timing retardation correction due to knocking.

In step 140, an ignition timing control signal forming process is started so that a fuel injection signal is applied from the control circuit 54 to the ignition plug 20 so that ignition is performed at the corrected ignition timing.

When the ignition key switch 75 is switched from ON to OFF (at this time, the operation of the control circuit 54 is maintained for a while by the action of the timer 8o). ), the process proceeds from step 100 to step 120, where a sensor correction coefficient calculation routine is executed. This routine is shown in detail in FIG. 5, in which the counter CTIME is incremented in step 12o1 and the counter CTI
It is determined whether the value of MH is larger than a predetermined value α. This value α is set depending on the time it takes for the pressure in the intake pipe where the oxygen sensor 70 is installed to reach atmospheric pressure after the engine is stopped, and is usually about 10 to 20 minutes. Conversely, the operating time of the timer 80 is set so as to maintain the operation of the control circuit 54 during this period.

If CTIME>α holds true, the process proceeds to step 1203, where the oxygen sensor output is read as 11', and in the next step 1204, the atmospheric pressure Pa from the atmospheric pressure sensor 71 is read.

In step 1205, the correction coefficient is calculated to be 0. This correction coefficient is used to correct the output of the oxygen sensor 70 to the reference value when the output of the oxygen sensor 70 changes from the reference value due to opening of the individual lid or change over time. In other words, the reference oxygen partial pressure PO□ and the oxygen sensor 70 are the basis for calculating the fuel injection amount and ignition timing.
The outputs are in the relationship shown by the solid line 1 in FIG. 6, and the fuel injection amount and ignition timing are calculated assuming that the oxygen sensor output is on this straight line β. However, the output characteristics change, for example, as indicated by the broken line m, due to individual opening of the sensor or changes over time. However, this change merely changes the slope while maintaining the linearity of the partial pressure and output. Therefore,
By multiplying and correcting the detected value of the oxygen sensor by a predetermined correction coefficient, the characteristics indicated by the broken line can be modified to resemble those indicated by the solid line, and ideal fuel injection and ignition timing control can be performed.

That is, if the output of the standard sensor is I+' and the output of the oxygen sensor that has changed over time is II', If' = KX
II' ■. On the other hand, since the oxygen sensor output is proportional to the oxygen partial pressure, it can be calculated by 11'=CXPO□ ■, and in this case, the oxygen sensor output indicates that a considerable amount of time has passed since the engine ignition key switch 75 was turned off. Therefore, the partial pressure within atmospheric pressure is being detected. On the other hand, if the atmospheric pressure is Pa, the oxygen partial pressure in the atmosphere is 0.209, so Pa'''0.209 XPO2■ From ■, ■, and ■, K = (0 ,209X CX Pa)/I lc
■It becomes. Let this value be 0.

In step 1206, the current value K of the correction coefficient is determined. , the previous value Kl, the average correction coefficient, number KAv by 2 to the value before the previous time.
I! KAVI! = (Ko +1 +2)/3
Calculated by ■.

In step 1207, for the next calculation, to Crab 2,
-Ko is put in crab 1. KA in step 12o8
va, Ko, and K+ are stored in the nonvolatile area of RAM.

〔effect〕

A correction coefficient is calculated from the output value of the oxygen sensor and the output of the atmospheric pressure sensor 71 to determine the atmospheric pressure when the output of the oxygen sensor 70 corresponds to the atmospheric pressure, and the fuel injection amount is calculated regardless of inter-individual deviation or changes over time. In addition, the ignition timing can be set to an appropriate value. Therefore, it is possible to prevent the air-fuel ratio from becoming rough and the torque from fluctuating.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of the present invention. FIG. 2 is a schematic diagram of the overall system configuration of an embodiment of the present invention. 3, 4 and 5 are flowcharts illustrating the operation of the control circuit. FIG. 6 is a graph showing the relationship between oxygen partial pressure and oxygen sensor output. 10... Cylinder block, 12... Piston 16
... Cylinder head, 18... Combustion chamber 20... Spark plug, 30... Distributor 32... Surge tank, 42... Injector 46... EGR valve,
49...Pressure regulating valve, 54...Control circuit 56.58...
・Crank angle sensor 66...Throttle valve opening sensor 68...Exhaust side oxygen sensor 70...Intake side oxygen sensor 71...Atmospheric pressure sensor 75...Ignition key switch 80...Timer number Figure Figure Calculation routine for sensor correction coefficient Figure Partial pressure (PO2) Figure

Claims (1)

[Claims] A control device for an internal combustion engine comprising the following components, a control means for controlling control factors of the internal combustion engine, and a control device arranged in an intake pipe of the internal combustion engine to control the oxygen partial pressure of gas introduced into the engine. sensor means for detecting; atmospheric pressure detecting means for detecting atmospheric pressure around an internal combustion engine; oxygen sensor calibration condition determining means for determining calibration conditions for an oxygen sensor in which a detection value of the oxygen sensor responds to atmospheric pressure; means for calculating a calibration value of the detection value of the oxygen sensor by comparing the detection value of the oxygen sensor with the detection value of the atmospheric pressure detection means under the conditions, and controlling by adding calibration to the output value of the oxygen sensor by the amount of the calibration value. Means for applying to means.