JPH0735749B2 - Atmospheric pressure prediction method for internal combustion engine control - Google Patents

Description

The present invention relates to an atmospheric pressure prediction method for controlling an internal combustion engine for controlling the fuel injection amount and ignition timing of the internal combustion engine based on the atmospheric pressure, In particular, the present invention relates to an atmospheric pressure prediction method for controlling an internal combustion engine equipped with an exhaust gas recirculation device (hereinafter referred to as “EGR device”).

[Conventional technology]

BACKGROUND ART Conventionally, an internal combustion engine that controls a fuel injection amount and an ignition timing based on an intake pipe pressure (absolute pressure) and an engine rotation speed has been known. Also in this internal combustion engine, exhaust gas is recirculated to an intake system to reduce NO. An EGR device that reduces _X is provided. Some of the EGR devices include an EGR installed on the EGR valve.
EG detects the back pressure (exhaust gas pressure) in the constant pressure chamber of the vacuum modulator and keeps this back pressure near atmospheric pressure.
There is a back pressure control method that keeps the EGR rate constant by adjusting the EGR port negative pressure that acts on the diaphragm chamber of the R valve and controlling the EGR valve by this EGR port negative pressure. In an internal combustion engine equipped with such an EGR device, the combustion state changes between when the EGR device is operating and when it is not operating, so that the fuel injection amount and ignition timing are controlled by switching depending on whether the EGR device is operating or not operating. I have to. Further, in the back pressure control type EGR device as described above, since the EGR valve is controlled by the EGR port negative pressure adjusted by the EGR bakumimodulator, it is unlikely that the low-speed traveling has changed to the high-altitude traveling. When the atmospheric pressure changes, the operating area changes. Therefore,
If the ignition timing is controlled by erroneously determining that the EGR device is operating even though the EGR device is not operating, the ignition timing when the EGR device is operating is more advanced than the ignition timing when the EGR device is not operating. Since it is set to, there is a problem that knocking occurs due to over-advance. Therefore, in the past, EGR
Regardless of whether the device is operating or not, the ignition timing is adjusted to the retard side by adjusting the ignition timing when the EGR device is not operating, and the fuel injection amount is controlled by learning control. In addition, it is determined whether the EGR device is activated by detecting whether the EGR valve is activated by a lift sensor or the like, and based on the determination result, the ignition timing and the fuel injection amount are controlled, and the atmospheric pressure sensor is detected. Is used to detect the atmospheric pressure, it is determined whether the EGR device is operating from the detected atmospheric pressure, and the ignition timing and the fuel injection amount are controlled based on the determination result.

By the way, in the method of retarding the ignition timing, there is a problem that fuel consumption is deteriorated because the ignition timing is retarded even in the normal operating range of the EGR device during lowland traveling. In addition, the method using the lift sensor or the atmospheric pressure sensor has a problem that the cost becomes expensive because these sensors are required.

Therefore, the intake pipe pressure is detected when the engine speed is in a predetermined range, and it is determined whether or not the EGR device is operating based on the atmospheric pressure predicted from the intake pipe pressure. There is.

[Problems to be solved by the invention]

However, when the atmospheric pressure is predicted from the intake pipe pressure according to the engine speed and whether the EGR device is operating or not, and the ignition timing is controlled based on the predicted atmospheric pressure, the actual atmospheric pressure is Although the atmospheric pressure is low and the EGR device is not operating, the predicted atmospheric pressure is high due to the actual atmospheric pressure.
The EGR device may be erroneously determined to be operating, and the ignition timing may be advanced.

The present invention has been made in view of the above facts, depending on the predicted atmospheric pressure, for example, although the EGR device is not operating, erroneously determined that the EGR device is operating,
An object of the present invention is to provide an atmospheric pressure prediction method for controlling an internal combustion engine, which does not cause a problem such as an excessive advance of ignition timing.

[Means for Solving the Problems] The present invention for achieving the above-mentioned object is a differential pressure from the reference atmospheric pressure of the intake pipe pressure measured in the fully open state of the throttle valve, and the engine speed is equal to or less than a predetermined value. Internal combustion engine control that obtains the detected atmospheric pressure from the intake pipe pressure measured in the region where the throttle valve opening is equal to or greater than a predetermined value, and obtains the predicted atmospheric pressure for internal combustion engine control with respect to the actual atmospheric pressure based on the detected atmospheric pressure When the detected atmospheric pressure falls below a predetermined range with respect to the predicted atmospheric pressure that has already been obtained, a first value is subtracted from the predicted atmospheric pressure to obtain the detected atmospheric pressure. When the predicted atmospheric pressure has already exceeded a predetermined range with respect to the predicted atmospheric pressure already calculated, the predicted atmospheric pressure is updated by adding a second value smaller than the first value to the predicted atmospheric pressure already calculated. And

[Action]

To explain the principle of the present invention, when the throttle valve is in the fully open state, the intake pipe pressure is
It is lower than the reference atmospheric pressure (for example, 1 atmospheric pressure) by a predetermined amount, and this predetermined amount is considered to be substantially constant regardless of the altitude change. Therefore, when the atmospheric pressure changes due to a change in altitude, the intake pipe pressure when the throttle valve is fully opened changes according to the actual change in atmospheric pressure.

On the other hand, in the region where the engine speed is equal to or lower than the predetermined speed and the opening of the throttle valve is equal to or higher than the predetermined amount, the intake pipe pressure hardly changes even if the engine speed or the opening of the throttle valve changes. Therefore, the intake pipe pressure in this region is substantially equal to the intake pipe pressure when the throttle valve is fully opened.

Therefore, by predetermining the difference PMA between the intake pipe pressure and the reference atmospheric pressure when the throttle valve is fully opened, the intake pipe measured in the region where the engine speed is equal to or lower than a predetermined speed and the opening degree of the throttle valve is equal to or higher than a predetermined amount. Pressure PM and differential PMA
Therefore, the atmospheric pressure can be obtained without using an atmospheric pressure sensor or the like. (Detection atmospheric pressure PM + PMA).

In the present invention, the atmospheric pressure obtained from the intake pipe pressure is set as the detected atmospheric pressure (PM + PMA), and the predicted atmospheric pressure PMatm for controlling the internal combustion engine is sequentially updated based on the detected atmospheric pressure.

This update of the predicted atmospheric pressure is performed when the detected atmospheric pressure PM + PMA changes and exceeds the predetermined range α with respect to the previously calculated predicted atmospheric pressure PMatm. At this time, if the detected atmospheric pressure PM + PMA is higher than the predicted atmospheric pressure PMatm already obtained, the second value (predetermined value K5) is added to the predicted atmospheric pressure PMatm, and the detected atmospheric pressure Patm is increased.
When M + PMA is low, the first value (predetermined value K4) is subtracted from the predicted atmospheric pressure PMatm to obtain a new predicted atmospheric pressure.

Since the second value K5 for increasing the predicted atmospheric pressure is set smaller (K4> K5) than the first value K4 for decreasing the predicted atmospheric pressure, the detected atmospheric pressure PM + PMA is larger than the predicted value. When it becomes higher than the atmospheric pressure PMatm, it is possible to suppress the predicted atmospheric pressure PMatm from rising, and it is possible to ensure safety when controlling the internal combustion engine.

If the internal combustion engine is controlled based on the updated predicted atmospheric pressure in this manner, for example, the atmospheric pressure for determining whether the EGR device is operating is higher than the actual atmospheric pressure. Therefore, although the actual atmospheric pressure is low and the EGR device is not operating, it is judged that the EGR device is operating and the ignition timing advance control is performed. It is possible to prevent the occurrence of.

〔The invention's effect〕

As described above, according to the present invention, when predicting the atmospheric pressure for controlling the internal combustion engine based on the atmospheric pressure detected without using the atmospheric pressure sensor or the like, it is predicted to be higher than the actual atmospheric pressure. It is possible to prevent it. This allows, for example, E
It is possible to prevent the ignition timing from being excessively advanced due to the misjudgment that the GR device is operating and to prevent the occurrence of knocking, and to appropriately control the internal combustion engine such as the fuel injection amount and the ignition timing. The effect of, is obtained.

〔Example〕

Next, an internal combustion engine (engine) including an ignition timing control device and a fuel injection amount control device to which the present invention is applicable will be described in detail with reference to the drawings. FIG. 2 shows an outline of this internal combustion engine. On the downstream side of the air cleaner (not shown),
A throttle valve 10 whose opening is controlled in conjunction with the accelerator pedal is arranged. This slot valve 10 is
It is connected to the dump point 12 via 11. The duty port 12 is connected to the upstream side of the throttle valve 10 via a negative pressure delay valve 14 in which an orifice and a check valve are arranged in parallel. Further, the throttle valve 10 is provided with a throttle opening sensor 24 including a potentiometer for detecting the opening of the throttle valve 10. A surge tank 18 is arranged downstream of the throttle valve 10, and the surge tank 18 is connected to a combustion chamber formed in the engine body via an intake manifold 22.
A diaphragm-type pressure sensor 20 is attached to the surge tank 18. A fuel injection valve 16 is attached to the intake manifold 22 for each cylinder so as to project into the intake manifold 22.

The combustion chamber formed in the engine body is communicated with the catalyst device filled with the three-way catalyst via the exhaust manifold 26. An O ₂ sensor 56 that outputs a signal inverted at the stoichiometric air-fuel ratio is attached to the exhaust manifold 26. Further, a water temperature sensor 48 for detecting the engine cooling water temperature is attached to the engine block of the engine body so as to penetrate the engine block and project into the water jacket.

An exhaust gas circulation path 27 is arranged so as to connect the exhaust manifold 26 and the surge tank 18, and an EGR valve 36 is attached in the middle of the exhaust gas circulation path 27. E
The diaphragm chamber 37 of the GR valve 36 is connected to an EGR port 32 formed slightly upstream of the throttle valve 10 via a negative pressure passage 35 in which an EGR vacuum modulator 28 is arranged. The EGR chamber modulator 28 is divided into a constant pressure chamber 31 and an atmosphere chamber 33 communicating with the atmosphere by a diaphragm 29 having a valve body 30, and a spring 34 is arranged in the atmosphere chamber 33. . The constant pressure chamber 31 of the EGR vacuum modulator 28 is in communication with the EGR valve 36.

A spark plug (not shown) is attached to each cylinder so as to penetrate the cylinder head of the engine body and project into the combustion chamber. This spark plug is connected to a control circuit 44 via a distributor 41 and an igniter 38. It is connected to the. A cylinder discriminating sensor 40 and a rotation angle sensor 42, each of which is composed of a signal rotor fixed to the distributor shaft and a lockup fixed to the distributor housing, are mounted in the distributor 41. In the case of a 6-cylinder engine, the cylinder discrimination sensor 40 outputs a cylinder discrimination signal to the control circuit 44 at every 720 ° CA, for example.
The rotation angle sensor 42 outputs an engine rotation speed signal to the control circuit 44, for example, every 30 ° CA.

The control circuit 44 includes a microcomputer. That is, the control circuit 44 includes a random access memory (RAM) 58, a read only memory (ROM) 60, a micro processing unit (MPU) 6 as shown in FIG.
2, input / output port 64, input port 66, output port 68, 70
And a bus 72 such as a data bus or a control bus that connects them. An analog-digital (A / D) converter 74 and a multiplexer 76 are connected to the input / output port 64. The multiplexer 76 is connected to the pressure sensor 20 via the CR filter 78 composed of the resistor R and the capacitor C, the water temperature sensor 48 via the buffer 80, and the throttle opening sensor 24 via the buffer 81. Are connected. CR Filter 78
The time constant of is large enough to remove the pulsating component of the intake pipe absolute pressure (3 to 5 msec). MPU62 is an input / output port
The A / D converter 74 and the multiplexer 76 are controlled via 64, and the output of the pressure sensor 20, the output of the water temperature sensor 48 and the output of the throttle opening sensor 24 are sequentially A / D converted and stored in the RAM. The A / D conversion cycle of the pressure sensor output is, for example, 12 msec. The input port 66 has a comparator 82 and a buffer.
Waveform shaping circuit with O ₂ sensor 56 connected via 84
The cylinder discrimination sensor 40 and the rotation angle sensor 42 are connected via 86. The output port 68 is connected to the igniter 38 via a drive circuit 88, and the output port 70 is connected to the fuel injection valve 16 via a drive circuit 90 having a down counter. Reference numeral 92 is a clock and 94 is a timer. the above
The ROM contains the control routine program and EGR described below.
A map of the ignition advance angle, a map of the basic fuel injection time, and the like depending on whether the device is operating or not are stored in advance.

Next, the operation of the above EGR device will be described with reference to FIG. When the opening of the throttle valve 10 increases, the EGR port 32
A negative pressure acts on the diaphragm, and this negative pressure is supplied to the diaphragm chamber 37 of the EGR valve 36 via the EGR vacuum modulator 28. On the other hand, the exhaust gas is supplied from the exhaust manifold 26 via the exhaust gas circulation path 27 and the EGR valve 36 to the constant pressure chamber 31 of the EGR vacuum modulator 28. here,
When the back pressure is higher than the atmospheric pressure by a set value (determined by the elastic force of the spring and diaphragm), the negative pressure passage 35 is closed by the valve body 30 of the EGR vacuum modulator 28, and the negative pressure generated at the EGR port 32 is generated. The pressure acts directly on the diaphragm chamber 37 of the EGR valve via the negative pressure passage 35, and the negative pressure causes the EGR valve 36 to open, so that the exhaust gas is supplied from the exhaust manifold 26 to the surge tank 18 via the exhaust gas circulation path 27. It When the engine load decreases and the back pressure decreases, the pressure acting on the constant pressure chamber 31 of the EGR vacuum modulator 28 decreases, so that the negative pressure passage 35 is gradually opened by the atmospheric pressure acting on the atmosphere chamber 33 and becomes negative. Since the atmosphere is introduced into the pressure passage 35, the negative pressure acting on the diaphragm chamber 37 is reduced. As a result, the EGR valve 36 is gradually closed and the amount of exhaust gas supplied into the surge tank 18 is reduced. When the back pressure decreases to a pressure close to the atmospheric pressure, the valve body 30 is completely opened and atmospheric pressure acts on the diaphragm chamber 37 through the atmosphere chamber 33, so that the EGR valve 36 is closed and the surge tank 18 is closed. Exhaust gas supply is stopped. As described above, according to this EGR device, the amount of exhaust gas proportional to the back pressure is supplied to the intake system, whereby the EGR rate can be kept constant with respect to the engine load. Also, when the back pressure becomes close to atmospheric pressure (actually, it is lower than atmospheric pressure by a specified value), the operation of this EGR device is started, so if the atmospheric pressure changes due to altitude change, the operating range of the EGR device also changes. Will be done.

Next, the above EG where the operating range changes due to changes in atmospheric pressure.
The control routine of the first embodiment of the present invention for determining the operating range of the R device will be described. FIG. 4 shows a routine for calculating the predicted atmospheric pressure PMatm. In Step 100, the change amount of the intake pipe pressure PM or the intake pipe pressure PM at every predetermined time.
It is determined whether or not the engine is in the steady operation state by determining whether or not the amount of change between the weighted average value of 1 and the intake pipe pressure PM detected this time is a predetermined value or less. When it is determined that the engine is in the steady operation state, the engine speed NE is set to the predetermined value K in step 102.
Judge whether it is 1 or less. Engine speed NE is a predetermined value K
When it is judged to be 1 or less, the differential pressure PMA from the reference atmospheric pressure of the intake pipe pressure PM when the throttle valve is fully opened is calculated from the map shown in FIG. 5 in step 104 according to the current engine speed NE (fifth In the figure, the differential pressure from 1 atm
PMA is shown). At the next step 106, it is determined whether or not the throttle opening TA is equal to or larger than a predetermined opening K2.
When the determination at step 106 is affirmative, that is, when the engine speed NE is the predetermined value K1 or less and the throttle opening TA is the predetermined opening K2 or more, the intake pipe pressure changes due to the change in the throttle opening and the change in the engine speed. It is determined that the vehicle is operating in a specific A region within the B region shown in FIG. 6 which does not change, and the following steps are executed. Where differential pressure PMA
Indicates the differential pressure from the actual atmospheric pressure. Since the intake pipe pressure PM in the area A is approximately equal to the intake pipe pressure in the fully open state of the slott valve, PM + PMA (hereinafter referred to as detected atmospheric pressure) is approximately the actual atmospheric pressure. Will be equal. At step 108, the value obtained by subtracting the predetermined value α from the predicted atmospheric pressure PMatm and the detected atmospheric pressure P
M + PMA is compared, and in step 112, a value obtained by adding a predetermined value α to the predicted atmospheric pressure PMatm is compared with the detected atmospheric pressure PM + PMA. If the detected atmospheric pressure PM + PMA exists within the range of PMatm ± α, this routine is terminated without changing the predicted atmospheric pressure PMatm. If the detected atmospheric pressure PM + PMA is smaller than PMatm−α, the predicted atmospheric pressure PMatm is calculated in step 110. From the predetermined value K4
The value obtained by subtracting is the predicted atmospheric pressure PMatm.
The detected atmospheric pressure PM + PMA so that the detected atmospheric pressure PM
If + PMA is larger than PMatm + α, step 114 adds a predetermined value K5 (where K5 <K4) to the predicted atmospheric pressure PMatm to increase the predicted atmospheric pressure PMatm so that the predicted atmospheric pressure PMatm approaches the detected atmospheric pressure PM + PMA. Here, K5 <K4 is set in order to predict the atmospheric pressure at a low level in consideration of safety.

FIG. 1 shows an interrupt routine interrupted each time A / D conversion of the intake pipe pressure PM is completed. Step 100 to step 1
At 06, similarly to the above, it is judged whether or not the steady operation is performed in the area A shown in FIG. 6, and if the judgment is affirmative, at step 120, the predicted atmospheric pressure PMatm and the detected atmospheric pressure PM + PM are detected.
Compare with A. Detected atmospheric pressure PM + PMA is predicted atmospheric pressure PMatm
In the following cases, that is, when the detected atmospheric pressure is decreasing (when traveling from the lowland to the highland), the detected atmospheric pressure PM + PMA is set as the predicted atmospheric pressure PMatm in step 124, and the process proceeds to step 126. On the other hand, when it is determined in step 106 that the throttle opening TA is less than the predetermined opening K2, that is, it is determined that the steady operation is performed in the region B of FIG. 6, the predicted atmospheric pressure PMatm and the detected atmospheric pressure are detected in step 122. Compare with PM + PMA. And the predicted atmospheric pressure PMatm
Is smaller than the detected atmospheric pressure PM + PMA, that is, when the detected atmospheric pressure becomes large (when traveling from a highland to a lowland), the detected atmospheric pressure PM + P is obtained in step 124.
Set MA to the predicted atmospheric pressure PMatm. Thus, the predicted atmospheric pressure PMatm is gradually decreased when traveling from the lowland to the highland, and the predicted atmospheric pressure PMatm is gradually increased when traveling from the highland to the lowland.

At step 126, a value obtained by subtracting a predetermined value K3 from the predicted atmospheric pressure (usually a value of about 60 mmHg is adopted as the differential pressure from the atmospheric pressure for operating the EGR device) is set as the EGR device operating pressure PM _EGR, and at step 128 the intake pipe Compare pressure PM and EGR device operating pressure PM _EGR . If the intake pipe pressure PM is lower than the EGR device operating pressure PM _EGR , the negative pressure acting on the EGR port 32 directly acts on the diaphragm chamber 37 of the EGR valve 36 to open the EGR valve 36 and recirculate the exhaust gas to the intake system. If it is determined that step 130
Set flag XEGR with and at step 132 E
The basic ignition advance angle θ _BASE is calculated from the map that stores the basic ignition advance angle during GR operation. On the other hand, when the intake pipe pressure PM is equal to or higher than the EGR device operating pressure PM _EGR , the negative pressure acting on the diaphragm chamber 37 of the EGR valve 36 is small and it is determined that the EGR valve 36 is closed, and the flag XEGR is set at step 134. After resetting, at step 136, the basic ignition advance angle θ _BASE is calculated from the map storing the ignition advance angle at which the EGR device is not operated. EG
The ignition advance map when the R device is operating is set to the advance side of the ignition advance map when the EGR device is not operating. And
The _actual ignition advance angle θ is obtained by correcting the basic ignition advance angle θ _BASE with the engine cooling water temperature or the like.

FIG. 7 shows a routine for calculating the fuel injection time TAU. In step 140, it is judged whether or not the flag XEGR is set. If the flag XEGR is set, in step 142 the basics for operating the EGR device are determined. The basic fuel injection time TP is calculated from the map storing the fuel injection time, and if the flag XEGR is reset, E is set in step 144.
The basic fuel injection time TP is calculated from the map that stores the basic fuel injection time when the GR device is not operating. And step 146
At, the basic fuel injection time TP is corrected based on the intake air temperature, the engine cooling water temperature, etc. to calculate the fuel injection time TAU.

After the execution ignition advance θ and the fuel injection time are obtained as described above, the ignition timing and the fuel injection amount are controlled as usual.

Next, a second embodiment of the present invention for determining whether the EGR device is operating will be described. In the present embodiment, the atmospheric pressure is predicted by using the learning value for altitude compensation. FIG. 8 shows a learning routine for updating the learning value for controlling the air-fuel ratio to the stoichiometric air-fuel ratio in the present embodiment. At step 150, the air-fuel ratio feed back correction coefficient FAF.
Judge whether it is the timing to skip (usually changing around 1.0). If it is determined to be the timing to skip, the weighted average value FAFS of the air-fuel ratio feedback back correction coefficient calculated last time in step 152.
Calculate the weighted average value FAFSM of the air-fuel ratio feedback correction coefficient according to the following equation (1) based on the current value of the air-fuel ratio feedback correction coefficient FAF and the weighted average value FAFSM calculated last time by weighting M. To do.

At the next step 154, it is determined whether or not the weighted average value FAFSM of the air-fuel ratio feedback correction coefficient is within ± 0.2% of 1.0. If the determination at step 154 is affirmative, the update of the learning value is completed. And step 156, flag X
FGOK is set, and if the determination in step 154 is negative, it is determined that the update of the learning value is not completed, and in step 158 the flag XFGOK is reset. At the next step 160, the average value FAFAV of the air-fuel ratio feedback correction coefficient is calculated by obtaining the arithmetic mean of the current value FAF of the air-fuel ratio feedback correction coefficient and the value FAFO of the air-fuel ratio feedback backup correction coefficient at the previous skip timing. Is calculated. And
At step 162, the value FAF of the current air-fuel ratio feedback correction coefficient FAF is set to the previous air-fuel ratio feedback correction coefficient FAFO.
Memorize as. At step 164, whether the engine cooling water temperature is a predetermined value (for example, 80
Or more), whether the engine load is within a predetermined range, or whether the air-fuel ratio feedback correction coefficient has skipped a predetermined number of times (for example, five times) after the air-fuel ratio feedback control was started. It is determined whether or not the learning condition is satisfied by. When all of the above conditions are satisfied, it is determined that the learning condition is satisfied, and in step 166, the average value FAFAV of the air-fuel ratio feedback back correction coefficient is a predetermined value (for example,
1.02) It is judged whether or not it exceeds. If the determination in step 166 is affirmative, the learning value FG is increased by a predetermined value (for example, 0.002) in step 168, and the process proceeds to step 174. On the other hand, when the determination in step 166 is negative, it is determined in step 170 whether the average value FAFAV of the air-fuel ratio feedback correction coefficient is less than a predetermined value (for example, 0.98), and the step is determined.
If the determination at 170 is affirmative, the learning value at step 172.
Decrease FG by a predetermined value (for example, 0.002) and proceed to step 174. The average value FA of the air-fuel ratio feedback correction coefficient
If FAV is within the predetermined range, the process proceeds to step 174 without updating the learning value FG. At step 174, a skipping process is performed by adding a proportional constant to the current value of the air-fuel ratio feedback back correction coefficient. On the other hand, if it is determined in step 150 that it is not the skip timing, in step 176 an integration constant is added to the air-fuel ratio feedback correction coefficient to perform the integration processing of the air-fuel ratio feedback correction coefficient.

As a result of the skip processing and integration processing of the air-fuel ratio feedback correction coefficient as described above, the air-fuel ratio feedback correction coefficient FAF changes as shown in FIG. Further, the learning value FG updated as described above is applied to the following equation to obtain the fuel injection time TAU.

TAU ← TP ・ (FAF + FG) (2) As mentioned above, the average value FA of the air-fuel ratio feedback back correction coefficient
When FAV exceeds the specified value, that is, when the air-fuel ratio is leaner than the theoretical air-fuel ratio, the learning value is increased and the fuel injection amount is increased, and when the average value FAFAV is less than the specified value, the learning value is decreased. Since the fuel injection amount is reduced, even if the air-fuel ratio feedback correction coefficient FAF changes due to a manufacturing error or a change in atmospheric pressure, it is corrected by the learning value FG and the air-fuel ratio is controlled to the stoichiometric air-fuel ratio.

FIG. 10 shows a routine similar to that of FIG. 1 of the present embodiment. In steps 100 to 106, it is judged whether or not a steady operation is performed within the area A of FIG. 6 as in the case of FIG. If this determination is affirmative, the detected atmospheric pressure PM + PMA is predicted atmospheric pressure PMatm ± predetermined value α in steps 180 and 182.
Judge whether it is inside or not. Detection atmospheric pressure PM + PMA
Is within the predicted atmospheric pressure PMatm ± α, it is determined in step 186 whether or not the flag XFGOX is set. When the detected atmospheric pressure PM + PMA is equal to or higher than the predicted atmospheric pressure PMatm + α or the detected atmospheric pressure PM + PMA is If the estimated atmospheric pressure PMatm-α or less, the weight of the estimated atmospheric pressure PMatm is weighted in step 184, and the weighted average value is calculated according to the following equation (3) based on the estimated atmospheric pressure and the detected atmospheric pressure. The weighted average value is used as the value of the predicted atmospheric pressure PMatm.

When it is determined in step 186 that the flag XFGOX has been set, that is, when the learning is finished, the count value CPMOK is incremented in step 188, and the integrated value FGSUM of the previous learning value is added in step 190. The current learning value FG is added to calculate the cumulative value FGSUM of learning values, and the atmospheric pressure detected in step 192 is detected.
PM + PMA is added to the predicted atmospheric pressure integrated value PMatmSUM to calculate the predicted atmospheric pressure integrated value PMatmSUM. In step 194, it is determined whether or not the count value CPMOK has exceeded the predetermined value K6. If this determination is affirmative, the count value CPM is determined in step 196.
PMOK is set to 0, and the integrated value FGS of learning values is set in step 198.
The average value FGAV of learning values is obtained by dividing UM by a predetermined value K6.
Is calculated, and the integrated value PMa of the predicted atmospheric pressure in step 200 is calculated.
tmSUM divided by a predetermined value K6 Predicted average atmospheric pressure PMatmAV
Is calculated. Then, in step 202, the integrated value F of the learning values is
Set the cumulative value PMatmSUM of GSUM and predicted atmospheric pressure to 0.

As a result of the above, the average value PMatmAV of the predicted atmospheric pressure within the predetermined count value K6 when operating in the region A of FIG.
And an average value FGAV of learning values is calculated.

In step 204, the differential pressure DLP from 1 atm is obtained by subtracting the average value PMatmAV of the predicted atmospheric pressure from 1 atm (760 mmHg).
Calculate M. At the next step 206, the learning value for advanced compensation FGHAC corresponding to the differential pressure DLPM is calculated from the map shown in FIG. 12, and at step 208 the learning value for advanced compensation FGHAC is subtracted from the average value FGAV of learning values to produce the manufacturing error. Learning value for compensation FGB
Ask for A. Then, in step 210, using the manufacturing error compensation learning value FGBA and the previously calculated weighted average value FGB, the weighted average value (average value of learning values based on the manufacturing error of the pressure sensor) FGB is calculated according to the following formula. To do.

Here, the learning value FG for air-fuel ratio feedback control is expressed by the following formula when a volume flow meter such as a Kalman flow meter is used.

FG = FGHAC + FGB (5) where FGHAC is a learning value for altitude compensation, and FGB is a learning value for manufacturing error compensation for compensating for changes in the air-fuel ratio due to manufacturing errors in the volume flow meter.

The relationship of the above equation (5) is always established regardless of changes in the intake air amount, the engine rotation speed, and the like. Further, the manufacturing error compensation learning value FGB hardly changes with time. Therefore, the altitude is predicted by predicting the atmospheric pressure under the predetermined operating condition and obtaining the differential pressure DLPM between the predicted atmospheric pressure and the reference atmospheric pressure (760 mmHg in step 204).
Calculate the learning value FGHAC for altitude compensation from (predicted altitude),
In equation (5) above, learning value FG is changed to learning value FG for altitude compensation.
By subtracting HAC, the manufacturing error compensation learning value FGB can be obtained. Then, the learning value for manufacturing error compensation FGB obtained in the predetermined operating state is used to obtain the learning value for altitude compensation in other operating states, and the differential pressure corresponding to the reference atmospheric pressure is obtained from this learning value for altitude compensation. By subtracting the differential pressure from the reference atmospheric pressure, the atmospheric pressure in all operating conditions can be predicted.

Therefore, in this embodiment, the average value FGAV of the learning values and the average value PMatmAV of the predicted atmospheric pressure when operating in the region A of FIG. 6 are obtained in steps 188 to 202, and the reference atmospheric pressure is obtained in step 204. (For example, 760 mmHg), subtract the average value PMatmAV of the predicted atmospheric pressure to obtain the differential pressure DLP shown in FIG.
Ask for M. This differential pressure DLPM corresponds to the altitude based on the altitude of the place of the standard atmospheric pressure (usually based on the average sea level). Also, learning value FGHAC for altitude compensation and differential pressure DLPM
That is, since the altitude corresponds to that shown in FIG. 12, the altitude compensation learning value FGHAC corresponding to the differential pressure DLPM is calculated in step 206. Then, in step 208, the learning value for manufacturing error compensation FGBA is obtained by subtracting the learning value for advanced compensation FGHAC from the average value FGAV of learning values, and in step 210, the weight of the learning value for manufacturing error compensation is calculated according to the above equation (4). Calculate the average value FGB.

Further, in the next step 212, it is determined whether or not the updating of the learning value is completed by determining whether or not the flag XFGOK is set. When the flag XFGOK is set, the advanced compensation learning value FGHAC1 is obtained in step 214 by subtracting the weighted average value FGB of the manufacturing error compensation learning values from the learning value FG. Next step
In 216, the learning value FGHAC for altitude compensation is calculated from the map shown in FIG.
The differential pressure DLPM corresponding to 1 is calculated, and the
Predicted atmospheric pressure PMat corresponding to the differential pressure DLPM from the map shown in the figure
Calculate m1.

Thereby, as described above, it is possible to predict the atmospheric pressure in all operating states from the learning value for manufacturing error compensation obtained in the predetermined operating state.

In steps 220 to 224, the predicted atmospheric pressure PMatm obtained during operation in the area A of FIG. 6 is compared with the predicted atmospheric pressure PMatm1 obtained from the learning value for altitude compensation, and either of them is smaller for safer control. The other value is the atmospheric pressure PMB. Then, in step 226, the pressure difference K3 necessary for operating the EGR device is subtracted from the atmospheric pressure BMB to calculate the EGR device operating pressure PM _EGR , and in step 228 the intake pipe pressure PM and the engine speed N
Based on E and, the basic ignition advance angle θ ₁ when the EGR device is not operating is calculated, and the intake pipe pressure PM is calculated at step 230.
And the EGR device operating pressure PM _EGR are compared to determine whether the EGR device is operating. When it is determined that the intake pipe pressure PM is equal to or higher than the EGR device operating pressure PM _EGR and the EGR device is not operating, the basic ignition advance angle θ _{1 is set} to the basic ignition advance angle θ _BASE in step 238. On the other hand, if it is determined in step 230 that the intake pipe pressure PM is smaller than the EGR device operating pressure PM _EGR and the EGR device is operating, the correction advance value θ ₂ at the time of operating the EGR device is set to the intake pipe pressure PM in step 232. Is calculated based on the engine rotation speed NE and the basic ignition advance angle θ _BASE is a value obtained by adding the basic ignition advance angle θ ₁ and the corrected advance angle value θ _{2 at} step 234.

FIG. 13 shows a fuel injection amount calculation routine of the present embodiment. In step 240, the intake pipe pressure PM and the EGR device operating pressure PM _EGR are compared, and when it is determined that the EGR device is operating, At step 242, the basic fuel injection time TP is calculated from the map when the EGR device is operating based on the intake pipe pressure and the engine speed, and when it is determined that the EGR device is not operating, the EGR device is not operating at step 244. The basic fuel injection time TP is calculated from the time map based on the intake pipe pressure and the engine speed. And step 24
At 6, the basic fuel injection amount TP is corrected based on the intake air temperature, the engine cooling water temperature, etc. to calculate the fuel injection amount TAU.

As described above, according to the present embodiment, unlike the first embodiment, the atmospheric pressure can be predicted regardless of the magnitude of the throttle opening. Therefore, when a vehicle equipped with a large displacement engine climbs a gentle road (the throttle opening is performed). Even if the degree is less than or equal to a predetermined value), the effect that the atmospheric pressure can be predicted is obtained.

[Brief description of drawings]

FIG. 1 is a flow chart showing an A / D conversion end interrupt routine of the first embodiment of the present invention, and FIG. 2 is an outline of an internal combustion engine equipped with a fuel injection amount control device and an ignition timing control device to which the present invention is applicable. 3 and 4 are block diagrams showing details of the control circuit shown in FIG. 2, FIG. 4 is a flow chart showing a routine for calculating the predicted atmospheric pressure according to the first embodiment of the present invention, and FIG. A diagram showing the differential pressure up to the intake pipe pressure when the throttle valve is fully opened,
FIG. 6 is a diagram showing a region where the intake pipe pressure does not fluctuate, and FIG.
FIG. 8 is a flow chart showing the fuel injection amount calculation routine of the first embodiment, FIG. 8 is a flow chart showing the learning routine of the second embodiment of the present invention, and FIG. 9 is a diagram showing changes in the air-fuel ratio feedback back correction coefficient. FIG. 10 is a flow chart showing a routine similar to FIG. 1 of the second embodiment, FIG. 11 is a diagram showing a deviation from the reference atmospheric pressure, and FIG. 12 is a differential pressure and a learning value for altitude compensation. And FIG. 13 is a flow chart showing a fuel injection amount calculation routine of the second embodiment. 16 …… Fuel injection valve, 28 …… EGR vacuum modulator, 36 …… EGR valve.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location F02D 43/00 N F02M 25/07 550 R F02P 5/15

Claims (1)

[Claims] 1. An intake pipe measured in a region where an engine speed is equal to or lower than a predetermined value and an opening of the throttle valve is equal to or more than a predetermined value, and a differential pressure of the intake pipe pressure measured in a fully open state of the throttle valve. Calculate the detected atmospheric pressure from the pressure,
A method for predicting an atmospheric pressure for controlling an internal combustion engine with respect to an actual atmospheric pressure based on the detected atmospheric pressure, which is an atmospheric pressure predicting method for controlling an internal combustion engine, wherein the detected atmospheric pressure has already been calculated for the predicted atmospheric pressure. The first value is subtracted from the predicted atmospheric pressure when the pressure falls below a predetermined range, and the predicted atmospheric pressure is already calculated when the detected atmospheric pressure exceeds the predetermined range with respect to the predicted atmospheric pressure already calculated. A predicted atmospheric pressure is updated by adding a second value smaller than the first value to the predicted atmospheric pressure for controlling an internal combustion engine.