JPH07189773A - Fuel supply control device for internal combustion engine with supercharger - Google Patents

Abstract

(57) [Abstract] [Purpose] In an internal combustion engine with a supercharger, corrects the phase shift related to the intake air flow rate detection to reduce the difference between the detected supercharging pressure and the actual inflow pressure. [Structure] Based on a value obtained by dividing the opening area A by the engine rotation speed Ne, a cylinder volume efficiency QHφ is searched and obtained from a map (S9). The supercharging pressure sensor 21 detects the supercharging pressure detection signal PB (S10), and the supercharging pressure detection signal PB is set to 1
A weighted average P of the boost pressure detection signal PB for performing the next delay process.
BAV (= [(2 ^X −1) × PB + PBAV ₋₁ ] /
2 ^X ) is calculated to obtain a correction coefficient KPB for correcting the maximum basic fuel injection amount TpMAX (S12).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply control system for an internal combustion engine with a supercharger, and more particularly, to deterioration of fuel controllability due to a phase shift in detecting an intake air flow rate in the internal combustion engine with a supercharger. And a device capable of preventing

[0002]

2. Description of the Related Art In a control device for electronically controlling the amount of fuel supplied to an internal combustion engine, an air flow meter for detecting the intake air flow rate of the engine is provided, and the intake air flow rate Q and the engine rotation speed N detected by the air flow meter are provided. The basic fuel supply amount Tp is variably set based on
It is general that the fuel supply amount to the engine is controlled based on the above (see JP-A-58-150040 and JP-A-59-49334).

Further, it is general practice to provide a supercharger and supercharge the intake air supplied to the internal combustion engine to improve the output and fuel consumption generated by the internal combustion engine.
Here, in the one provided with the fuel supply control device for setting and controlling the fuel supply amount based on the intake air flow rate Q detected by the air flow meter, the fuel supply amount is controlled assuming that the volume efficiency does not change. However, in an internal combustion engine configured to perform supercharging by the supercharger, the pressure in the supercharging chamber between the compressor of the supercharger and the throttle valve may change suddenly during a transient period. Since such a sudden change in pressure may cause a rapid change in the charging efficiency due to supercharging, the supercharging pressure by the supercharger is detected, and the change in the charging efficiency is made based on the detected supercharging pressure. The detection is performed (see Japanese Patent Laid-Open No. 4-191445).

[0004]

However, since the fuel supply amount is controlled by the basic fuel supply amount Tp set based on the intake air flow rate Q detected by the air flow meter, the intake air detected by the air flow meter is controlled. There is a difference in the phase shift due to supercharging between the air flow rate and the air flow rate actually flowing into the cylinder, and it is necessary to correct it.

Since the sensor for detecting the supercharging pressure by the supercharger is also fixed at a predetermined position, there is a difference in response delay between the position of the sensor and the pressure of the air actually flowing into the cylinder. The difference is caused by the supercharging pressure and steady / transient. If the intake air flow rate is corrected with a value that is not related to the required pressure, the air-fuel ratio fluctuates and controllability deteriorates. There was a fear.

The present invention has been made in view of the above situation, and in an internal combustion engine with a supercharger, even during a transient state, etc.
The purpose is to correct the phase shift related to the detection of the intake air flow rate, reduce the difference between the detected boost pressure and the pressure of the air actually flowing into the cylinder, and prevent the deterioration of fuel controllability. And

[0007]

Therefore, according to the present invention, the intake air flow rate detecting means for detecting the intake air flow rate of the engine on the upstream side of the compressor of the supercharger and the engine rotational speed detecting means for detecting the rotational speed of the engine are provided. And a basic fuel supply amount setting means for setting a basic fuel supply amount to the engine based on the detected intake air flow rate and the engine rotation speed, and fuel to the engine based on the set basic fuel supply amount. A fuel supply control device for an internal combustion engine with a supercharger, comprising: a fuel supply control means for controlling supply; a supercharging pressure detecting means for detecting supercharging pressure by the supercharger; Correction amount setting means for performing a first-order delay process on the boost pressure detection value detected by the detection means to set a correction amount related to a phase shift due to supercharging of the intake air flow rate detection value; and the basic fuel supply amount. Basic fuel set by setting means It has a configuration provided with a correction means for correcting the correction amount set injection quantity by the correction amount setting means.

[0008]

With this configuration, the correction amount related to the phase shift due to the supercharging of the intake air flow rate detection value is set based on the value obtained by subjecting the supercharging pressure detection value to the first-order lag processing. The basic fuel injection amount is corrected. That is, there is a difference in the phase shift due to supercharging between the supercharging pressure detected by the supercharging pressure detecting means and the actual supercharging pressure. Then, the correction is performed to minimize the difference. In particular, the difference in the phase shift due to supercharging between the detected supercharging pressure and the actual supercharging pressure is large at the time of a transition, etc., so that the true air amount can be made more accurate by the first-order delay processing at the time of a transition. As a result, the fuel supply to the engine can be controlled with higher accuracy.

[0009]

EXAMPLES Examples of the present invention will be described below. In FIG. 1 showing an embodiment, an internal combustion engine 2 having an exhaust turbocharger 1 as a supercharger rotationally drives an exhaust turbine 4 of the exhaust turbocharger 1 by the energy of exhaust gas discharged through an exhaust passage 3. As a result, the compressor 6 provided in the intake passage 5 and axially connected to the exhaust turbine 4 is rotationally driven to supercharge the intake air.

The control unit 15 has an intake air flow rate signal Q directly detected by a hot-wire air flow meter 11 as an intake air flow rate detecting means interposed in the intake passage 5 upstream of the compressor 6, and a downstream side of the compressor 6. Throttle valve opening signal TVO detected by a throttle sensor 13 attached to a throttle valve 12 installed in the intake passage 5 of the engine, and a rotation speed sensor 14 as engine rotation speed detecting means such as a crank angle sensor. The engine rotation speed signal Ne, the cooling water temperature signal Tw detected by the water temperature sensor 17 provided in the water jacket 16 of the engine 2, and the like are input.

A supercharging pressure sensor 21 as supercharging pressure detecting means for detecting the supercharging pressure P is provided on the downstream side of the compressor 6 and on the upstream side of the throttle valve 12, and the supercharging pressure sensor 21 is provided. The supercharging pressure detection signal PB is also input to the control unit 15. Then, the control unit 15 controls the intake air flow rate Q and the rotation speed sensor 14 detected by the hot-wire air flow meter 11.
The basic fuel injection amount (basic fuel supply amount) Tp (← K × Q / Ne; K is a constant) is calculated and set on the basis of the engine rotation speed Ne detected by the water temperature sensor 17. The final fuel injection amount Ti is set by correction based on the cooling water temperature Tw and the like detected by. Then, a drive pulse signal having a pulse width corresponding to the fuel injection amount Ti is output to the electromagnetic fuel injection valve 18 at a predetermined timing synchronized with the engine rotation, and the fuel injection valve 18 is operated for a time corresponding to the pulse width. The engine 2 is intermittently driven to open, and fuel is injected and supplied to the engine 2.

In the present embodiment, the control unit 15 is provided with software as functions of the basic fuel supply amount setting means, the fuel supply control means, the correction amount setting means, and the correcting means. The functions of the supply amount limiting device, the correction amount setting device, and the correction device are shown in the flowcharts of FIGS. 2 and 3
In the program shown in the flowchart of, first, in step 1 (denoted as S1 in the figure.
Throttle valve 12 detected by throttle sensor 13
The transient operation of the engine 2 is determined based on the change in the opening TVO.

Here, during deceleration operation in which the opening TVO of the throttle valve 12 is changing in the closing direction, the routine proceeds to step 2, where the deceleration determination flag Flugdec is set to 1. Then, in step 8, the throttle valve opening TVO detected by the throttle sensor 13 is converted into the opening area A of the throttle chamber portion in which the throttle valve 12 is inserted. That is, the opening area A corresponds to the opening area of the engine intake system which is variably controlled by the throttle valve 12.

In the next step 9, the cylinder volume efficiency QHφ is obtained by searching the map based on the value obtained by dividing the opening area A by the engine rotation speed Ne. In step 10, the boost pressure detection signal P detected by the boost pressure sensor 21.
Read B. In step 11, the weighted average PBAV of the boost pressure detection signal PB read in step 10 is calculated according to the following calculation formula.

PBAV = [(2 ^X −1) × PB + PBAV ₋₁ ] / 2 ^X However, PBAV ₋₁ is the weighted average PBAV obtained by the previous calculation, and 2 ^X is a constant indicating the weighting with respect to the previous value. is there. The calculation of the weighted average PBAV means that the boost pressure detection signal PB is subjected to the first-order delay processing. In step 12, a correction coefficient KP for correcting a maximum basic fuel injection amount TpMAX described later based on the weighted average PBAV of the calculated boost pressure detection signal PB.
B is obtained by referring to the map.

That is, there is a difference between the detected value detected by the supercharging pressure detection sensor and the actual supercharging pressure due to a phase shift due to supercharging of the exhaust turbocharger 1. The detection signal PB is subjected to first-order delay processing to minimize the difference. And in step 13,
The cylinder volume efficiency QHφ, the correction coefficient KPB, and
Basic fuel injection amount Tp equivalent to 100% cylinder volume efficiency
Based on MXφ, the maximum basic fuel injection amount TpMAX (regulated amount) is set according to the following formula.

TpMAX ← QHφ × KPB × TpMXφ That is, the cylinder volumetric efficiency QHφ is obtained from the opening area A and the engine speed Ne, and the basic fuel injection amount TpMXφ corresponding to 100% of the cylinder volumetric efficiency is calculated as the actual volumetric efficiency QH.
By multiplying by φ, the maximum basic fuel injection amount Tp commensurate with the intake air flow rate predicted from the opening area A and the engine rotation speed Ne is set, and at the same time, the change in volume efficiency due to the change in supercharging pressure is dealt with. Therefore, the correction coefficient KPB is multiplied to set the correction.

In step 14, a hot wire type air flow meter is used.
The basic fuel injection amount Tp (← K × Q / N set based on the intake air flow rate Q and the engine rotation speed Ne detected at 11)
e; K is a constant) and the maximum basic fuel injection amount TpMAX set in step 11 are compared, and the basic fuel injection amount Tp based on the detection result by the hot wire air flow meter 11 is Tp.
When it exceeds MAX, the routine proceeds to step 15, where TpMAX is set to the basic fuel injection amount Tp to prevent the final setting of the basic fuel injection amount Tp exceeding the maximum basic fuel injection amount TpMAX.

That is, in the engine 2 having a supercharger like the exhaust turbocharger 1 in the present embodiment, the supercharged air is suddenly shut off by the throttle valve 12 during deceleration, so that the air flows upstream of the compressor. There is a possibility of backflow, and the hot-wire type airflow meter 11 also detects this backflowing air amount in the same manner as the forward flow, and therefore detects a larger amount than the true throttle valve 12 passing air amount. . Therefore, during deceleration operation, the basic fuel injection amount Tp
May be set to a larger amount than the amount corresponding to the true intake air flow rate, and the air-fuel ratio may become overrich.

However, as described above, the cylinder volume efficiency QHφ obtained from the opening area A and the rotation speed N is used as a basis regardless of the value detected by the hot-wire air flow meter 11, and is corrected and set by the boost pressure PB. If the basic fuel injection amount Tp is regulated based on the maximum basic fuel injection amount TpMAX that is set, the maximum basic fuel injection amount Tp is set so as not to include the backflow amount as described above, and thus the amount does not include the backflow amount. The basic fuel injection amount Tp can be regulated, and the air-fuel ratio can be prevented from becoming excessively rich during deceleration operation.

Further, in this embodiment, the boost pressure detection signal PB is subjected to the first-order lag processing, and the maximum basic fuel injection amount TpMA is calculated based on the weighted average PBAV of the detection signal PB.
The correction coefficient KPB for correcting X is calculated, and even if supercharging is performed and the position where the supercharging pressure sensor 21 detects the supercharging pressure is different from the cylinder position, a difference in phase shift occurs, The difference can be reduced, and accordingly, the correction coefficient KPB can be accurately corrected to cope with the change in the volumetric efficiency due to the change in the supercharging pressure, and particularly, the correction of the intake air flow rate in the transient state. Will be improved in precision and controllability will be improved.

As described above, during deceleration operation, the basic fuel injection amount Tp based on the hot-wire air flow meter 11 is restricted to the maximum basic fuel injection amount TpMAX, but immediately after the deceleration operation is changed to the steady operation. Also, similar regulations are being implemented continuously. That is, when it is determined in step 1 that the throttle valve opening TVO is substantially constant and the engine 2 is in steady operation, step 3
Go to step 1 and set 1 for deceleration operation Deceleration flag Fl
Determine ugdec.

Here, the deceleration determination flag Flugdec is set to 1
When it is determined that is set, it is during steady operation immediately after deceleration operation, and at this time, the predetermined time TMDEC for continuing the regulation by TpMAX as described above even after the transition to steady operation is set to the engine speed Ne or the excessive speed. Supply pressure PBA
Set based on V. It should be noted that the time period during which the regulation of the basic fuel injection amount Tp is continued is variably set according to the engine speed Ne or the level of the supercharging pressure PBAV, and the regulation by TpMAX is continued within the time period in which the backflow is predicted to occur. In particular, since the backflow continues to occur longer during deceleration from a high load state, the higher the engine speed N or the supercharging pressure PBAV in the first deceleration determination is,
The predetermined time TMDEC is set to be long.

After the TMDEC is set for a predetermined time in step 4, the deceleration determination flag Flugdec is reset to zero in step 5, and then the process proceeds to step 8 to set TpMAX similar to that used in the deceleration determination and the TpMAX. The basic fuel injection amount Tp is restricted. On the other hand, when it is determined in step 3 that the deceleration determination flag Flugdec is set to zero, the process proceeds to step 6 and it is determined whether or not the TMDEC is zero.

When the TMDEC is not zero, the routine proceeds to step 7 to decrease the TMDEC by 1, then proceeds to step 8 and thereafter to regulate the basic fuel injection amount Tp based on TpMAX, and at step 6, TMDEC.
When it is determined that the EC is zero, the routine jumps to step 18 and the basic fuel injection amount Tp is not regulated by TpMAX.

That is, the time TMDEC is set at the first transition from the steady operation to the deceleration operation, and then this time TMD is set.
EC is decreased by 1 each time this program is executed, and the basic fuel injection amount T is decreased until it is counted down to zero.
P is continuously regulated by TpMAX, and when it becomes zero, the regulation is canceled after that. It is possible to prevent the air-fuel ratio from becoming excessively rich due to the detection of the reverse flow of intake air during the steady operation immediately after deceleration. .

On the other hand, when it is judged at step 1 that the engine 2 is in the acceleration operation state, the routine proceeds to step 16, where the deceleration judgment flag Flugdec is reset to zero and
In step 17, the TMDEC is reset to zero, and the routine proceeds to step 16 without restricting the basic fuel injection amount Tp.
Therefore, once the deceleration operation is changed to the steady operation, the TM
When the predetermined time is set in DEC and the acceleration operation is started before TMDEC is counted down to zero, the regulation of the basic fuel injection amount Tp is immediately canceled, and the basic fuel injection by acceleration is performed. Avoid increasing changes in the amount Tp being disturbed by TpMAX.

In step 18, the basic fuel injection amount Tp regulated by TpMAX is averaged during a deceleration operation and within a predetermined time after the deceleration shift to a steady state, and the final basic fuel injection amount Tp is calculated. Set. The basic fuel injection amount Tp after the averaging process is corrected based on the cooling water temperature Tw detected by the water temperature sensor 17 to determine the final fuel injection amount Ti.
A drive pulse signal with a pulse width equivalent to
Is output to fuel injection and supply.

In this embodiment, the engine provided with the exhaust turbocharger 1 as the supercharger has been described, but the supercharger may be a direct engine driven supercharger. Further, in the present embodiment, the hot wire type air flow meter 11 was used, but this is the same as shown in the present embodiment in the system including the air flow meter that detects the backflow generated during deceleration similarly to the normal detection value. This is because the TpMAX regulation is effective, and the hot-wire air flow meter is not particularly limited.

[0030]

As described above, according to the present invention, in the internal combustion engine with a supercharger, a phase due to supercharging is provided between the supercharging pressure detected by the supercharging pressure detecting means and the actual supercharging pressure. Since there is a difference related to the deviation, the supercharging pressure detection value is subjected to the first-order lag processing and is corrected to minimize the difference. Therefore, the intake air flow rate detecting means detects the intake air flow rate. The basic fuel supply amount set based on the detected air flow rate can be set as the basic fuel supply amount considering the phase shift due to supercharging, and the fuel supply to the engine can be controlled with higher accuracy, for example There is an effect that it becomes possible to avoid overriching of the fuel ratio.

[Brief description of drawings]

FIG. 1 is a system schematic diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing how control is performed in the embodiment.

FIG. 3 is a flowchart showing how control is performed in the embodiment.

[Explanation of symbols]

 1 Exhaust Turbocharger 2 Internal Combustion Engine 5 Intake Passage 11 Air Flow Meter 14 Rotational Speed Sensor 15 Control Unit 18 Fuel Injection Valve

Claims (1)

[Claims] 1. An intake air flow rate detecting means for detecting an intake air flow rate of an engine upstream of a compressor of a supercharger, an engine rotation speed detecting means for detecting a rotation speed of an engine, and the detected intake air flow rate. Basic fuel supply amount setting means for setting a basic fuel supply amount to the engine based on the engine speed, and fuel supply control means for controlling fuel supply to the engine based on the set basic fuel supply amount, In a fuel supply control device for an internal combustion engine with a supercharger, the supercharging pressure detecting means for detecting a supercharging pressure by the supercharger, and the supercharging pressure detecting means for detecting the supercharging pressure detected by the supercharging pressure detecting means. Correction amount setting means for performing a first-order delay process on the value to set a correction amount related to a phase shift due to supercharging of the intake air flow rate detected value, and a basic fuel injection amount set by the basic fuel supply amount setting means The correction amount setting means The fuel supply control device for supercharged internal combustion engine, characterized in that a, a correction means for correcting by more set correction amount.