JPH01240741A - Fuel supply amount control method for internal combustion engine - Google Patents

Abstract

PURPOSE:To avoid dispersion of an air-fuel ratio by adjusting a correction amount of fuel supply according to a change in an intake air temperature caused by exhaust gas recirculating. CONSTITUTION:An exhaust gas intake port 7 and an exhaust gas fill port 8 are mutually connected communicably through an exhaust gas recirculating control valve 20. A basic intake air amount is read by means of table search by using an engine speed detected by an engine speed 51 and an intake pipe pressure detected by an intake pipe pressure senser 52 as arguments so as to correct it by an intake air temperature detected by an intake air temperature senser 53, so that the intake air amount is decided. Thereby, it is possible to avoid dispersion of an air-fuel ratio over the whole of an operation range containing the starting/closing time of exhaust gas recirculating.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for controlling the amount of fuel supplied to an internal combustion engine used in vehicles such as automobiles, and more specifically to a method for controlling the amount of fuel supplied for exhaust gas recirculation. This relates to the correction method.

[Prior Art] In internal combustion engines in which exhaust gas recirculation is performed, for various purposes, for example, in internal combustion engines of the type in which the fuel supply amount is controlled using intake pipe pressure as a parameter, exhaust gas recirculation is performed. In order to compensate for the fact that the calculated value of the fuel injection amount deviates from the appropriate value for the actual intake air amount due to a change in the relationship between the intake pipe pressure and the intake air amount (fresh air) due to circulation, or exhaust gas recirculation. In order to ensure stable operation of internal combustion engines, it has been conventional practice to correct the fuel supply amount by decreasing or increasing the fuel supply amount during exhaust gas recirculation. 48-27130, JP-A-59-20542, and JP-A-59-192838.

[Problems to be Solved by the Invention] When exhaust gas recirculation is performed, exhaust gas is added to the intake air, so the intake air temperature increases and the intake air density changes. Therefore, corrections to the fuel supply amount regarding exhaust gas recirculation should also take this into consideration.

Furthermore, if the exhaust gas recirculation passage and intake passage are cold when exhaust gas recirculation starts, the temperature of the exhaust gas supplied to the intake passage will decrease until they warm up, so even if exhaust gas recirculation is started, the temperature of the exhaust gas supplied to the intake passage will decrease. The intake air temperature does not rise immediately, and even if exhaust gas recirculation is stopped at the end of exhaust gas recirculation, the intake air temperature does not suddenly decrease until the temperature of the intake passage falls. The amount of correction for the fuel supply amount should be set in consideration of the transient temperature characteristics at the start and end of the fuel supply.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel supply amount correction method that takes into account the above-mentioned matters and performs fuel supply amount correction for optimum exhaust gas recirculation.

[Means for Solving the Problems] According to the present invention, the above-mentioned object is to control the fuel supply amount according to the operating state of the internal combustion engine, and to control the fuel supply amount with respect to exhaust gas recirculation during exhaust gas recirculation. This is achieved by a fuel supply amount control method for an internal combustion engine, which is characterized in that the amount of correction is corrected in accordance with changes in intake air temperature due to exhaust gas recirculation.

[Operations and Effects of the Invention] According to the fuel supply amount control method according to the present invention, the fuel supply correction amount related to exhaust gas recirculation is corrected according to the change in intake air temperature due to exhaust gas recirculation, and thereby the exhaust gas recirculation Regardless of whether the engine is started or stopped, variations in the air-fuel ratio are avoided, and stable drivability is ensured.

[Example] The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an example of a fuel supply amount control device and associated devices used to carry out the method for correcting the fuel supply amount for an internal combustion engine according to the present invention. In FIG. 1, 1 indicates an internal combustion engine, and the internal combustion engine 1 takes in air through a throttle valve 2, a surge tank 4, an intake manifold 5,
Fuel such as gasoline is injected from a fuel injection valve 12, a mixture of fuel and air is ignited by a spark plug 13, and burned gas, that is, exhaust gas, is discharged to an exhaust manifold 6.

The WF air manifold 6 is provided with an exhaust gas intake boat 7 for exhaust gas recirculation, and the surge tank 4 is provided with an exhaust gas injection boat 8.
and exhaust gas injection boat 8 are exhaust gas recirculation conduit 9
, an exhaust gas recirculation control valve 20 and a conduit 10 .

The exhaust gas recirculation control valve 20 has an inlet port 21 and an outlet port 22, the inlet boat 21 being connected in communication with the exhaust gas intake boat 7 by a conduit 9 and the outlet boat 2
2 is connected in communication to the exhaust gas injection boat 8 by a conduit 10. The exhaust gas recirculation control valve 20 has a valve boat 23 and a valve element 24, and the valve port 23 is connected to the valve element 24.
The opening degree is controlled to control the exhaust gas recirculation flow rate. The valve element 24 is
It is connected to a step motor 33 and is driven to open and close by the step motor 33.

The fuel injection valve 12 is controlled by a fuel injection control device 60, the spark plug 13 is controlled by an ignition control device 61, and the step motor 3 is controlled by a fuel injection control device 60.
3 are operated and controlled by an exhaust gas recirculation control device 60, and the fuel injection control device 60, ignition control device 61, and exhaust gas recirculation control device 62 are controlled by a common microcomputer 5.
It operates based on a control signal from 0.

The microcomputer 50 receives information regarding the rotational speed of the internal combustion engine 1 from the rotational speed sensor 51 and the information about the rotational speed of the internal combustion engine 1 from the rotational speed sensor 51.
Information about the intake pipe pressure and atmospheric pressure is obtained from the intake pipe pressure, information about the intake air temperature is obtained from the intake air temperature sensor 53, information about the throttle opening of the throttle valve 2 is obtained from the throttle opening sensor 54, and information about the inside of the surge tank 4 is obtained from the surge tank internal temperature sensor 55. Information regarding the temperature of the cooling water is sent to the cooling water temperature sensor 5.
Information regarding the temperature of the cooling water of the internal combustion engine 1 is provided from 6, and based on this information, a control signal regarding the fuel injection amount and a control signal regarding the advance angle of the ignition timing are generated as a control signal for controlling the flow rate of exhaust gas recirculation. and the control device 60.
61.62.

The intake air temperature sensor 53 may be provided near the air cleaner on the upstream side of the throttle valve 2 in terms of the intake air flow.
It is designed to detect the temperature of intake air, especially fresh air.

A surge tank internal temperature sensor 55 may be attached to the surge tank 4, and during exhaust gas recirculation, this temperature sensor 55 detects the temperature of intake air to which exhaust gas has been added.

FIG. 2 shows one embodiment of a control system used to implement the method for controlling the amount of fuel supplied to an internal combustion engine according to the present invention.

The microcomputer 50 has an intake air amount determining means 70.
, a throttle effective cross-sectional area determining means 71, a throttle passing air amount estimating means 72, an EGR rate calculating means 73,
New partial pressure calculation means 74, basic injection time, basic advance amount,
It includes EGR valve opening amount determination means 75 and execution fuel injection time/execution advance amount determination means 76.

Next, one implementation of the method for controlling the amount of fuel supplied to an internal combustion engine according to the present invention will be explained using FIG.

First, in step 10, information, that is, parameters are input from various sensors.

In step 20, the basic intake air amount is read out by a table search using the engine speed Ne detected by the rotation speed sensor 51 and the intake pipe pressure Pi detected by the intake pipe pressure sensor 52 as arguments. is corrected by the intake air temperature To detected by the intake air temperature sensor 53 to determine the intake air amount GaO. Data table of intake air amount according to engine speed and intake pipe pressure (
map) is predetermined according to the intake pipe pressure and engine speed when exhaust gas recirculation is not performed.

In step 30, the throttle effective cross-sectional area St is determined from the throttle opening At detected by the throttle opening sensor 54. This throttle effective cross-sectional area St may be determined from a data map or by calculation.

In step 40, the intake pipe pressure PI and atmospheric pressure P detected by the intake pipe pressure sensor 52.

From the throttle effective cross-sectional area St and the intake air temperature To detected by the intake air temperature sensor 53, the throttle passing air amount G
A determination is made of ae. This throttle passing air jlGae is determined by the intake pipe pressure and the throttle effective cross-sectional area St.
The basic quantity may be found by a table search using as an argument, and it may be determined by correcting the basic quantity according to the intake air temperature TO and the atmospheric pressure Po.

In step 50, the EGR small R rate is calculated according to the following formula.

Re-IGao(To/Tc)-Gael/1Ga
o(To/Tc)+0.07Gael This EGR small R rate calculation formula includes the surge tank internal temperature Tc detected by the surge tank internal temperature sensor 55, so that the EGR small R rate calculated by this calculation formula The rate is accurate to take into account the decrease in intake air density due to the increase in intake air temperature due to exhaust gas recirculation.

In step 60, a new partial pressure Pa is calculated according to the following formula.

Pa=P+e(1-Re) The new partial pressure Pa corresponds to the intake pipe pressure of only fresh air, which is obtained by subtracting the EGR gas partial pressure among the two intake pressures detected by the intake pipe pressure sensor 52.

In step 70, the new partial pressure Pa and the engine speed Ne
The basic injection time T is determined by a table search using as an argument.
p, the basic advance angle amount Abse, and the EGR valve opening jlAegr are found.

In step 80, the fuel injection time and the advance angle amount are corrected according to the cooling water temperature Tv detected by the water temperature sensor 56 and other various parameters, and the effective fuel injection time TAU and the effective advance angle Af3HBe are calculated. are determined respectively.

EGR valve opening amount A egr is the exhaust gas recirculation control device 62
The exhaust gas recirculation flow rate is controlled by operating the step motor 33 based on this signal.

The signal of the execution fuel injection time TAU is sent to the fuel injection control device 60.
As a result, the fuel injection valve 12 is opened for an injection time determined by the effective fuel injection time ATU, and fuel injection is performed.

The execution advance angle flAexec is given to the ignition control device 61, whereby ignition timing control is performed using the advance angle.

FIG. 4 shows another example of a fuel supply amount control method and associated apparatus used to implement the fuel supply amount control method for an internal combustion engine according to the present invention.

In this embodiment, the valve element 24 of the exhaust gas recirculation control valve 20 is connected to a diaphragm 26 of a diaphragm device 25 and is connected to a compression coil spring when a negative pressure greater than a predetermined value is not introduced into the diaphragm chamber 27. 28 to close the valve boat 23, and when a negative pressure greater than a predetermined value is introduced into the diaphragm chamber 27, it rises against the spring force of the compression coil spring 28 in response to the negative pressure. The valve boat 23 is opened.

The diaphragm chamber 27 of the exhaust gas recirculation control valve 20 is connected via a conduit 29, a negative pressure adjustment valve 30 for controlling back pressure, and a conduit 31 to an intake pipe negative pressure take-out boat 32 provided in the surge tank. . As shown in the figure, the intake pipe negative pressure take-out boat 32 is provided downstream of the throttle valve 2 and is always subjected to intake pipe negative pressure.

The negative pressure regulating valve 30 has a valve element 36 that opens and closes the valve boat 35 and a diaphragm 37 supporting the valve element. A chamber 38 and a diaphragm chamber 39 are defined on the lower side, and the diaphragm is operated by the action of a compression coil spring 40 when pressure (positive pressure) higher than a predetermined value is not introduced into the diaphragm chamber 39. Valve element 3
6 is separated from the valve boat 35 to open the valve boat, and when a pressure higher than a predetermined value is introduced into the diaphragm chamber 39, it moves upward in the figure against the action of the compression coil spring 40. Displacing the valve element 36 to the valve port 35
The valve port is located in a position where the valve port is closed by contacting the valve port.

The diaphragm chamber 39 of the negative pressure regulating valve 30 is connected by a conduit 41 to a pressure chamber 43 between the valve port 23 of the exhaust gas recirculation control valve 20 and an orifice 42 provided downstream thereof. Exhaust gas pressure in the pressure chamber is introduced.

The structure consisting of the negative pressure regulating valve 30 and the orifice 42 as described above is a well-known back pressure control mechanism, and the diaphragm of the exhaust gas recirculation control valve 20 keeps the exhaust gas pressure in the pressure chamber 43 almost constant at all times. The negative pressure supplied to the chamber 20 is adjusted, in other words, the opening degree of the valve port 23 is adjusted, thereby maintaining the ratio of the exhaust gas recirculation flow rate to the intake air flow rate, that is, the EGR rate, almost constant at all times. It looks like this.

The atmosphere opening chamber 38 of the negative pressure regulating valve 30 is connected to an intake pipe negative pressure take-out boat 46 through a conduit 47 . The intake pipe negative pressure extraction boat 46 is located upstream of the throttle valve 2 when the opening is below a predetermined opening, and is located downstream of the throttle valve 2 when the opening is above the predetermined opening to remove the intake pipe negative pressure. It is now being influenced by

In this embodiment, the intake pipe negative pressure appearing on the intake pipe negative pressure take-out boat 46 according to the opening degree of the throttle valve 2 is supplied to the atmosphere opening chamber 38 of the negative pressure regulating valve 30, thereby achieving medium load operation. At times, the EGR rate will increase.

A negative pressure switching valve 45 is provided in the middle of the conduit 29.

The negative pressure switching valve (VSV) 45 is configured as an electromagnetically actuated three-way switching valve, and is connected to the boat a connected to the diaphragm chamber 27, the negative pressure boat b connected to the negative pressure regulating valve 34, and the atmosphere. When energized, that is, in the ON state, boat A is disconnected from atmospheric pressure boat C and connected to negative pressure boat B, whereas when not energized, that is, in the OFF state. In this state, boat a is disconnected from negative pressure boat b and connected to atmospheric pressure boat C. The supply of electricity to the negative pressure switching valve 45 is controlled by an electric control device 100 including a general microcomputer.

The control device 100 receives information regarding the engine speed from the rotation speed sensor 51, information regarding the intake pipe pressure from the intake pipe pressure sensor 52, information regarding the intake air temperature from the intake air temperature sensor 53, and information regarding the throttle opening from the throttle opening sensor 54. Information regarding the cooling water temperature of the internal combustion engine 1 is provided from the cooling water temperature sensor 56, and information regarding the exhaust gas recirculation passage temperature is provided from the exhaust gas recirculation passage temperature sensor 57. Based on these information, FIG. The fuel injection time of the fuel injection valve 12 is determined according to the flowchart shown in FIG. 1, and the energization to the negative pressure switching valve 45, that is, the start and end timing of exhaust gas recirculation is controlled.

An exhaust gas recirculation passage temperature sensor 57 is provided in the conduit 10, and may also be used as a sensor for EGR diagnosis.

Next, another method for controlling the amount of fuel supplied to an internal combustion engine according to the present invention will be described with reference to FIG.

First, in step 100, information, that is, parameters are input from various sensors.

In step 110, the basic injection time TP is read out by a table search using the intake pipe pressure Pa detected by the intake pipe pressure sensor 52 and the engine rotation speed Ne detected by the rotation speed sensor 51 as arguments. be exposed. The basic injection time TP is set to an appropriate value depending on the intake pipe pressure and engine speed under a condition where exhaust gas recirculation is not performed.

In step 120, the throttle opening Ta detected by the throttle opening sensor 54 and the rotation speed sensor 51 are checked.
The EGR correction amount T P egr of the fuel injection time is determined based on the engine rotation speed Ne detected by the engine speed Ne. This EGR correction JiTPegr includes a correction component that compensates for a decrease in intake air density due to an increase in intake air temperature due to exhaust gas recirculation, in addition to a correction component that corresponds to a change in the intake amount of fresh air due to exhaust gas recirculation. However, this correction component is preset to a constant value so as to be an appropriate value in a state where the increase in intake air temperature due to exhaust gas recirculation is saturated.

Note that this EGR correction jlTPegr may be set based on the intake pipe pressure, the intake air flow rate, the engine speed, and a combination thereof, in addition to the combination of the throttle opening and the engine speed.

In step 130, it is determined whether exhaust gas is being recirculated. If the exhaust gas is being recirculated, the process proceeds to step 140, and if the exhaust gas is not being recirculated, the process proceeds to step 160.

In step 140, the modified value T P teo('I
' is set to 1.

In step 150, a correction value T P teon is determined based on the exhaust gas recirculation passage temperature Te detected by the exhaust gas recirculation passage temperature sensor 57. As shown in FIG. 6, this correction value T P teon becomes 1 when the exhaust gas recirculation passage temperature To is low.
The above increase correction coefficient is shown, and the exhaust gas recirculation passage temperature T
As e increases, it decreases and approaches 1, and becomes 1 when the exhaust gas recirculation passage temperature Te reaches a predetermined value.

In step 160, the EGR correction amount TPeg is set to 0.
Then, the correction value T P teon is set to 1.

In step 170, a correction value T P teorr is determined based on the exhaust gas recirculation passage temperature Te detected by the exhaust gas recirculation passage temperature sensor 57. As shown in FIG. 7, this correction value T Pteoff exhibits a reduction correction coefficient of 1 or less when the exhaust gas recirculation passage temperature Te is high, and increases as the exhaust gas recirculation passage temperature To decreases. When the exhaust gas recirculation passage temperature Te decreases to a predetermined value, it becomes 1.

In step 180, the effective fuel injection time TAU is determined according to the following formula.

TAU=TPITHV ・THA(1-TPegr)T
Pteon @TPteorf) THW is a well-known warm-up correction coefficient determined according to the cooling water temperature Tv detected by the cooling water temperature sensor 56, and THA is determined according to the intake air temperature To detected by the intake air temperature sensor 53. This is a well-known intake temperature correction coefficient.

As described above, by setting the correction value T P teon or T P teorr depending on the exhaust gas recirculation passage temperature Te, fuel supply is performed according to the transient characteristics of the intake air temperature at the start and end of exhaust gas recirculation. The amount is corrected, thereby avoiding variations in the air/fuel ratio over the entire operating range, including at the beginning and end of exhaust gas recirculation.

Although the present invention has been described in detail above with reference to specific embodiments, it is understood that the present invention is not limited thereto and that various embodiments are possible within the scope of the present invention. This will be obvious to businesses.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an example of a fuel supply amount control device and associated devices used to implement the fuel zero (fuel amount correction method) for an internal combustion engine according to the present invention, and FIG. 2 is a schematic configuration diagram of an internal combustion engine according to the present invention. FIG. 3 is a block diagram showing an example of a control system used to implement the fuel supply amount control method of the present invention, FIG. FIG. 5 is a block diagram showing another example of a fuel supply amount control device and an accompanying device used to implement the fuel supply amount control method for an internal combustion engine according to the present invention. A flowchart showing another implementation point of the method, and FIGS. 6 and 7 are graphs showing correction value characteristics with respect to EGR passage temperature, respectively, used in the method for controlling the fuel supply amount of an internal combustion engine according to the present invention.1. ... Internal combustion engine 52 ... Throttle valve, 4 ... Surge tank, 5 ... Intake manifold, 6 ... Exhaust manifold, 7 ... Exhaust gas intake boat, 8 ...
Exhaust gas recirculation injection boat, 9.10... conduit, 12
...Fuel injection valve, 13...Spark plug, 20...
Exhaust gas recirculation control valve, 21... Inlet boat, 22.
...Exit boat. 23... Valve boat, 24... Valve element, 25... Diaphragm device, 26... Diaphragm, 27...
Diaphragm chamber, 28... Compression coil spring, 29...
- Conduit, 30... Negative pressure regulating valve, 31... Conduit, 32
...Intake pipe negative pressure take-out boat, 33...Step motor, 35...Valve boat, 36...Valve element, 37...
・Diaphragm, 38... Atmospheric release chamber, 39... Diaphragm chamber, 40... Compression coil spring, 41...
Conduit, 42...orifice. 43...Pressure chamber, 45...Negative pressure switching valve, 46...
Intake pipe negative pressure extraction boat, 47... Conduit, 50... Microcomputer 251... Rotation speed sensor, 52...
...Intake pipe pressure sensor, 53...Intake air temperature sensor, 5
4...Throttle opening degree, 55...Surge tank internal temperature sensor. 56...Cooling water temperature sensor, 57...Exhaust gas recirculation passage temperature sensor, 60...Fuel injection control device, 61
...Ignition control device, 62...Exhaust gas recirculation control device. 70... Intake air amount determination means, 71... Throttle nail effective cross-sectional area determination means, 72... Throttle passing air amount estimation means, 73... EGR rate calculation means, 74... New partial pressure calculation Means, 75...Basic injection time/basic advance amount/EGR valve opening amount determining means, 76...Executive fuel injection time/executive advance amount determining means, 100...Control device patent
Applicant Toyota Motor Corporation Representative
Person Patent Attorney Masatake AkashiFigure 3

Claims (1)

[Claims] Controls the fuel supply amount according to the operating status of the internal combustion engine, corrects the fuel supply amount in relation to exhaust gas recirculation during exhaust gas recirculation, and adjusts the correction amount according to changes in intake air temperature due to exhaust gas recirculation. A fuel supply amount control method for an internal combustion engine, characterized in that: