JP2000038953A - Controller for cylinder fuel injection type internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve ignitionability as well as relaxing vehicle shock by freely switching a burning condition into uniform burning and stratified burning, and setting a control parameter in relation to an injection rate on the basis of a result having demanded output torque change of an internal combustion engine and a result having judged the burning condition. SOLUTION: In an ECU 30 for detecting an operating condition of an inter- cylinder injection type internal combustion engine 1 and for inputting output signals of an air-fuel ratio sensor 15, an acceleration opening sensor 17, a crank angle sensor 18, and the like, a demand of output torque of the internal combustion engine 1 is judged, and it is also judged whether a burning condition in a combustion chamber is a stratified burning or not. A control parameter of the internal combustion engine 1 is set on the basis of a result judged the torque control demand and a result judged the burning condition. Namely, an injection rate is set to increase in the stratified burning when torque-up is demanded, and a throttle opening rate is set in non-stratified burning. On the other hand, the injection rate is set to decrease in the stratified burning when torque-down is demanded, and the throttle closing rate is set in the non-stratified burning.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for a direct injection type internal combustion engine, and more particularly to a direct injection type internal combustion engine for reducing a vehicle shock when an output torque control of the direct injection type internal combustion engine is requested. Related to the control device.

[0002]

2. Description of the Related Art Conventionally, in a port injection type internal combustion engine in which a homogeneous mixture of fuel and air is supplied to a combustion chamber in advance, an automatic transmission for vehicles, an anti-lock brake system (hereinafter simply referred to as "ABS"). A control device for mitigating a vehicle shock when a system such as a traction control system (hereinafter simply referred to as “TRC”) operates is known. In this control device, during the shift control of the automatic transmission for the vehicle, the ignition timing of the internal combustion engine is retarded and the throttle opening of the electronically controlled throttle is closed to reduce the output torque of the internal combustion engine or to open the throttle opening. By performing the control to increase the output torque of the internal combustion engine, a sudden change in the transmission output shaft torque during the shift control is controlled to reduce the shift shock. Also, at the time of the ABS control and the TRC control, the vehicle shock is reduced by performing the ignition timing retard control and the throttle closing control and the opening control by the electronic control throttle.

[0003]

SUMMARY OF THE INVENTION In a direct injection type internal combustion engine which can switch and control between uniform combustion and stratified combustion in accordance with the operation state, in a uniform combustion, as in a conventional port injection type internal combustion engine, the combustion chamber is placed in a combustion chamber. A uniform mixture of fuel and air is formed. Therefore, it is possible to reduce the vehicle shock due to the change in the output torque of the internal combustion engine by performing the ignition timing retard control and the throttle closing control and the opening control by the electronic control throttle.

However, in the stratified charge combustion, a combustible air-fuel mixture is present near the ignition plug to increase the air-fuel ratio of the portion,
Improves ignitability. Therefore, the time margin from the injection timing to the ignition timing is short, and it is necessary to control the injection timing and the ignition timing with high accuracy in order to ignite well. Therefore, if only the ignition timing retard control is performed in the same manner as in the uniform combustion, there is no gas mixture near the ignition plug at the time of ignition,
Instead of reducing the output torque, there is a problem that deterioration of combustion and misfire occur. In addition, in stratified combustion, since combustion is performed at an air-fuel ratio much smaller than the stoichiometric air-fuel ratio as compared with uniform combustion, the output torque of the internal combustion engine cannot be changed by throttle closing control or opening control using an electronically controlled throttle. Therefore, during stratified combustion, vehicle shock mitigation during shift control of the automatic transmission and during ABS control or TRC control was not sufficient.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and in a cylinder injection type internal combustion engine capable of controlling switching between uniform combustion and stratified combustion, any one of the cylinder injection type internal combustion engines can be provided with any output torque control request. It is an object of the present invention to provide a control apparatus for a direct injection internal combustion engine capable of appropriately controlling an output torque of the direct injection internal combustion engine even in a combustion state and reducing a vehicle shock.

[0006]

According to the first aspect of the present invention, there is provided a torque control request determining means (100) for determining a request for a change in output torque of a direct injection internal combustion engine. Combustion state determination means (103, 107) for determining whether the combustion state in the combustion chamber of the direct injection internal combustion engine is stratified combustion, and torque control request determination means (10).
0) and the combustion state determining means (103, 10).
Parameter setting means (104, 1) for setting control parameters of the direct injection internal combustion engine based on the determination result of 7).
05, 108 to 112).

According to this, when there is a request for the output torque control of the direct injection internal combustion engine, the control parameters of the direct injection internal combustion engine are set based on the combustion state in the combustion chamber. Therefore, optimal internal combustion engine control according to the combustion state becomes possible, and vehicle shock can be reduced in any combustion state. For example, as in the second aspect of the invention, when a request for increasing the output torque of the in-cylinder injection type internal combustion engine is made and the combustion state is stratified combustion, an increase in a parameter relating to the injection amount is set, and the combustion state is stratified combustion. If not, an increase in the parameter related to the intake air amount is set.

During stratified charge combustion, a uniform mixture is not formed in the combustion chamber, and a combustible mixture exists near the ignition plug.
During such stratified combustion, the output torque of the internal combustion engine can be increased by increasing the injection amount.
Further, when not in stratified combustion, that is, when a uniform mixture is formed in the combustion chamber, the output torque of the internal combustion engine can be increased by increasing the intake air amount.

Further, when the output torque of the in-cylinder injection type internal combustion engine is requested to be reduced and the combustion state is stratified combustion, a decrease in the parameter relating to the injection amount, the injection timing and the ignition are performed. At least one of the timing parameter and the retard amount is set, and when the combustion state is not stratified combustion, at least one of the reduction of the intake amount parameter and the ignition timing parameter is set.

At the time of stratified combustion in which a homogeneous mixture is not formed in the combustion chamber and a combustible mixture exists near the ignition plug,
If only the ignition timing is retarded, combustion deterioration or misfire occurs. However, the output torque of the internal combustion engine can be reduced by controlling a set of parameters related to the injection timing and the ignition timing. At the time of stratified combustion, the torque of the internal combustion engine can be reduced by reducing the injection amount. On the other hand, when the combustion is not stratified combustion, that is, when a homogeneous mixture is formed in the combustion chamber, the output torque of the internal combustion engine can be reduced by reducing the intake air amount or delaying the ignition timing.

Thus, when there is a request for the output torque control of the direct injection internal combustion engine, the control parameters of the direct injection internal combustion engine according to the combustion state in the combustion chamber are set. Therefore, the output torque of the internal combustion engine can be optimally controlled according to the combustion state, and the vehicle shock can be reduced in any combustion state.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying a control device for an internal combustion engine according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is an overall configuration diagram showing an internal combustion engine to which a control device for a direct injection internal combustion engine mounted on a vehicle according to an embodiment of the present invention and peripheral devices thereof.

In the present embodiment, the in-cylinder injection type internal combustion engine 1 has a stratified charge combustion in which a combustible mixture exists near an ignition plug and a uniform mixture of fuel and air is formed in a combustion chamber in accordance with an operation state. It is possible to switch and control the uniform combustion. The direct injection internal combustion engine 1 has four cylinders 1a,
A high-pressure fuel injection valve 2 for directly injecting fuel into each cylinder 1a
Is arranged. That is, the high-pressure fuel injection valve 2
Thus, the fuel can be directly injected into the cylinder 1a. The injection amount and the injection timing from the high-pressure fuel injection valve 2 are determined based on parameters relating to the injection amount and the injection timing which are set and output by an electronic control unit (hereinafter simply referred to as “ECU”) 30 described later. Is controlled.

Each cylinder 1a of the in-cylinder injection type internal combustion engine 1 absorbs pulsation of intake air through an intake valve (not shown), an intake port (not shown), and an intake manifold 5 upstream of the combustion chamber. The surge tank 6 communicates with the surge tank 6. A delivery pipe 3 for storing high-pressure fuel is arranged in each intake manifold 5, and a fuel pressure sensor 4 for detecting the fuel pressure inside the delivery pipe 3 is arranged in the delivery pipe 3. The delivery pipe 3 is connected to a high-pressure fuel pump 14 that is driven by the in-cylinder injection type internal combustion engine 1 and that is capable of sucking and discharging gasoline fuel stored in a fuel tank (not shown). The high-pressure fuel pumped from the fuel pump 14 is supplied to the high-pressure fuel injection valve 2 connected to the delivery pipe 3. Note that an ignition system including an ignition plug disposed in a combustion chamber of the in-cylinder injection type internal combustion engine 1 is omitted.

The surge tank 6 is connected to an air cleaner 8 via an intake pipe 7. A throttle valve 10 which is opened and closed by a drive motor 9 is provided in the intake pipe 7. The throttle valve 10 is of a so-called electronic control type. Basically, the drive motor 9 is driven based on parameters of a throttle opening amount and a closing amount set and output by the ECU 30. The opening and closing of the throttle valve 10 is controlled. By opening and closing the throttle valve 10, the amount of intake air introduced into the combustion chamber through the intake pipe 7 is adjusted.

Each cylinder 1a of the direct injection internal combustion engine 1 is connected to an exhaust manifold 11 via an exhaust valve (not shown) and an exhaust port (not shown) downstream of the combustion chamber.
The exhaust gas after combustion is discharged from an exhaust duct (not shown) via the exhaust manifold 11. The exhaust manifold 11 is provided with an air-fuel ratio sensor 15 that detects the air-fuel ratio (A / F) in the combustion chamber from the oxygen concentration in the exhaust gas.

The exhaust manifold 11 and the surge tank 6 are connected to each other by an exhaust gas circulation passage (hereinafter simply referred to as an “EGR passage”) 12.
An EGR valve 13 for controlling the amount of EGR recirculated from the exhaust manifold 11 into the surge tank 6 is provided in the middle of the operation. The output shaft of the direct injection internal combustion engine 1 is transmitted to the propeller shaft 22 via the torque converter 19 and the automatic transmission 40, and drives wheels (not shown). The automatic transmission 40 is provided with a lock-up control solenoid 20 for the torque converter 19 and a shift valve 21 for selecting a gear ratio.

The above-described ECU 30 is composed of a digital computer, and is connected to each other via a bidirectional bus 35 as a well-known central processing unit, a first CPU 31 and a second CPU 32, and a ROM (Read Only Memory) 33 storing a control program. , RAM for storing various data
(Random access memory) 34, an input port 36 for inputting detection signals from various sensors, an output port 37 for outputting control signals to various actuators, and the like. The first CPU 31 is mainly used for controlling the direct injection internal combustion engine 1, and the second CPU 32 is mainly used for controlling the automatic transmission 40 and the AB.
It is used for control other than the direct injection type internal combustion engine 1 such as S50 and TRC60.

An air-fuel ratio sensor 15 disposed in the exhaust manifold 11 detects an air-fuel ratio in the exhaust manifold 11. Then, the air-fuel ratio signal is input to an input port 36 via an analog / digital conversion circuit (hereinafter simply referred to as “A / D conversion circuit”) 38 in the ECU 30.
The accelerator pedal 16 includes the accelerator pedal 1.
An accelerator opening sensor 17 is connected as a load sensor that detects the accelerator opening according to the depression amount of the engine 6 and detects the load state of the in-cylinder injection type internal combustion engine 1. And
An output voltage signal proportional to the accelerator opening is transmitted to the ECU 3
The signal is input to the input port 36 via the A / D conversion circuit 38 in 0. Further, a crank angle sensor 18 provided on a crankshaft (not shown) of the in-cylinder injection type internal combustion engine 1
Detects the engine speed. Then, an output pulse signal proportional to the engine speed is input to the input port 36.

Further, a request signal for controlling the output of the internal combustion engine during the shift control of the automatic transmission 40 and the control of the ABS 50 and the TRC 60 as peripheral devices are also input to the input port 36. On the other hand, the output port 37 is provided with a drive motor 9 for controlling the opening and closing of the throttle valve 10, an EGR valve 13 for controlling the amount of EGR passing through the EGR passage 12, and an ignition plug (in each cylinder 1a) via a corresponding drive circuit 39. A high-pressure fuel injection valve 2 for each cylinder 1a, and a fuel pump 1 for supplying high-pressure fuel to the high-pressure fuel injection valve 2 for each cylinder 1a.
4. Shift valve 21 and lock-up control solenoid 2
Connected to 0. Then, the ECU 30 stores the ROM 33
According to the control program stored in the drive motor 9,
The EGR valve 13, the ignition plug (not shown), the high-pressure fuel injection valve 2, the fuel pump 15, the shift valve 21, and the lock-up control solenoid 20 are suitably controlled.

Next, a control processing routine in the first CPU 31 used in the control device for a direct injection internal combustion engine having the above-described configuration will be described with reference to a flowchart of FIG. First, at step 100, it is determined whether or not there is a request for controlling the output torque of the internal combustion engine from another system. The request for controlling the output torque of the internal combustion engine from the other system is made, for example, during the shift control of the automatic transmission 40 and the ABS 50 or TR.
It is input during control of C60. When the determination condition is satisfied in step 100, that is, when the output torque control request of the internal combustion engine is input, the process proceeds to step 101. If the determination condition is not satisfied, that is, if the output torque control request for the internal combustion engine has not been input, the process ends.

In step 101, it is determined whether or not the request for controlling the output torque of the internal combustion engine from another system is a request for increasing the torque. If the determination condition is satisfied, that is, if the output torque is increased, the process proceeds to step 102.
When the request is not the output torque increase control request, that is, when the output torque is decreasing request, the processing from step 106 is performed.

In step 102, the torque increase amount Tu
p is set. The torque increase amount Tup is determined based on the current operating state of the internal combustion engine (for example, the internal combustion engine speed, the automatic transmission 40, the ABS 50, the TRC 60, etc.)
The load is set from a map determined as a value necessary to suppress the vehicle shock under internal combustion engine load or the like.
After the torque up amount Tup is set, step 103
Then, the process proceeds to the combustion state determination process. In step 103,
It is determined from the various data held by the ECU 30 whether the current combustion state is stratified combustion. This is because the parameters used for the internal combustion engine output torque control differ depending on the combustion state.

In step 103, the judgment condition is satisfied,
That is, in the case of stratified combustion, the routine proceeds to step 104. Then, with reference to a map that defines the injection amount increase Qup, the injection amount increase Qup is calculated based on the torque increase amount Tup. In step 103, the determination condition is not satisfied, that is,
In the case of uniform combustion, the process proceeds to step 105. Then, referring to a map that defines the throttle opening amount TAup,
Throttle opening amount TA based on torque up amount Tup
Calculate up. Thus, depending on whether the determination condition in step 103 is satisfied, that is, whether stratified combustion or uniform combustion,
The different control parameters are set and the process ends.

Next, if the determination condition is not satisfied in step 101, that is, if a torque down request is made, the process proceeds to step 106. In step 106, the torque down amount Tdown is set. Like the torque up amount Tup, the torque down amount Tdown is set from a map determined as a value necessary for suppressing a vehicle shock in the current engine operating state for each system. After the torque down amount Tdown is set, the process proceeds to the combustion state determination processing of step 107.

In step 107, it is determined whether the current combustion state is stratified combustion. If the determination condition is satisfied in step 107, that is, if stratified charge combustion is performed, the process proceeds to steps 108, 109, and 110. Step 108 to step 110
Then, the injection amount decrease Qdown, the injection retard amount INJdown
n and a map defining the ignition retard amount SAdown,
Injection amount decrease Qdo based on torque down amount Tdown
wn, injection retard amount INJdown, and ignition retard amount SAd
calculate own.

If the determination condition is not satisfied in step 107, that is, if the combustion is uniform, the process proceeds to steps 111 and 112. Step 111 and step 1
In step 12, the ignition retard amount SAdown and the throttle closing amount TAdown are calculated based on the torque down amount Tdown with reference to a map that defines the ignition retarding amount SAdown and the throttle closing amount Tdown.

As described above, even when the output torque control request of the internal combustion engine from another system is a torque down request,
Different control parameters are set depending on whether the determination condition in step 107 is satisfied, that is, whether stratified combustion or uniform combustion, and the process ends. In stratified combustion, when responding to a torque-down request, the ignitability deteriorates unless the injection timing and the ignition timing are changed as a set, so that the two parameters are simultaneously retarded.

The parameters set in the above control processing are used by the first CPU 31. Then, various devices are controlled from the output port 37 via the corresponding drive circuit 39 to control the output torque of the internal combustion engine. In particular,
The throttle opening amount TAup set in step 105 and the throttle closing amount TAdo set in step 112
Based on wn, the drive motor 9 is controlled to control the opening and closing of the throttle valve 10, and the intake air amount is adjusted. Also, the injection amount increase Qup set in step 104, step 108
The high-pressure fuel injection valve 2 is controlled on the basis of the injection amount decrease Qdown set in step (1) and the injection retard amount INJdown set in step 109, and the injection amount and the injection timing are adjusted. Further, a plug (not shown) in the cylinder 1a is controlled based on the ignition retard amount SAdown set in steps 110 and 111, and the ignition timing is adjusted.

According to this embodiment, when there is a request from another system for controlling the output torque of the direct injection internal combustion engine 1, the control parameters set according to the combustion state of the direct injection internal combustion engine 1 are set. Changing. Therefore, by controlling the internal combustion engine according to the combustion state, it is possible to appropriately control the output torque of the internal combustion engine and reduce the vehicle shock in both the uniform combustion and the stratified combustion.

For example, the throttle opening amount is set when the output torque of the internal combustion engine is increased, and the ignition retard amount and the throttle closing amount are set when the output torque of the internal combustion engine is decreased, as in the conventional port type internal combustion engine during uniform combustion. In addition, the vehicle torque is reduced by controlling the output torque of the internal combustion engine. Also,
During stratified combustion, the injection amount is set when the output torque of the internal combustion engine is increased, and the injection amount, injection timing and ignition timing are set when the output torque of the internal combustion engine is reduced, and the output torque of the internal combustion engine is controlled to mitigate vehicle shock. ing.

(Other Embodiments) In the above embodiment, when the output torque of the internal combustion engine is required to be reduced and uniform combustion is performed, control is performed by both the ignition timing and the throttle opening.
However, the control may be performed using only one of the ignition timing and the throttle opening according to the standard of the vehicle shock mitigation required for the vehicle. In the case of stratified charge combustion, retard control was performed by a set of the injection amount, the injection timing, and the ignition timing. However, control using only the injection amount parameter or control using only the injection timing and ignition timing parameters may be performed in accordance with the vehicle shock mitigation standard required for the vehicle. Further, the retard amount of the retard control of the set of the injection timing and the ignition timing may be the same or may have an offset.

In the above-described embodiment, the internal combustion engine capable of switching between two combustion states, that is, uniform combustion and stratified combustion, has been described. However, the control processing routine of the above-described embodiment can also be applied to an internal combustion engine having the above two states and the other state, for example, an intermediate combustion state between uniform combustion and stratified combustion. Also in this case, it is necessary to control the injection timing and the ignition timing simultaneously only in the case of stratified combustion. This is because, even in the case of a combustion state intermediate between uniform combustion and stratified combustion, a uniform mixture is formed in the combustion chamber, so that the output torque can be controlled by setting the same parameters as in the uniform combustion. . Therefore, the determination of the combustion state may be a determination as to whether or not stratified combustion is performed, as in the above embodiment.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a direct injection internal combustion engine control apparatus according to an embodiment.

FIG. 2 is a flowchart showing a control routine of the in-cylinder injection type internal combustion engine control device according to the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... In-cylinder injection type internal combustion engine, 1a ... Cylinder, 2 ... High pressure fuel injection valve, 3 ... Delivery pipe, 4 ... Fuel pressure sensor, 7
... intake pipe, 9 ... drive motor, 10 ... throttle valve, 14
... High-pressure fuel pump, 15 ... Air-fuel ratio sensor, 19 ... Torque converter, 20 ... Lock-up control solenoid, 2
1: shift valve, 22: propeller shaft, 30: EC
U, 31: first CPU, 32: second CPU, 33: RO
M, 34 RAM, 35 bi-directional bus, 36 input port, 37 output port, 38 A / D conversion circuit, 39
Drive circuit, 40: automatic transmission, 50: ABS, 60: T
RC.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 41/04 310 F02D 41/04 310G 330 330P 330G 335 335A 335G 41/34 41/34 E F02P 5/15 F02P 5/15 B

Claims (3)

[Claims] 1. A control apparatus for a direct injection internal combustion engine that directly injects fuel into a combustion chamber capable of switching between uniform combustion and stratified combustion in accordance with an operation state, the output torque of the direct injection internal combustion engine. Torque control request determination means (100) for determining a change request; and combustion state determination means (103, 10) for determining whether the combustion state in the combustion chamber of the direct injection internal combustion engine is stratified combustion.
7) a parameter setting means for setting a control parameter of the in-cylinder injection type internal combustion engine based on a result of the discrimination by the torque control request discriminating means (100) and a result of discrimination by the combustion state discriminating means (103, 107). (104, 105, 10
8 to 112). A control device for a direct injection internal combustion engine, comprising: 2. The torque control request determination means (100).
When the request for increasing the output torque of the in-cylinder injection type internal combustion engine is determined, the stratified combustion is determined by the combustion state determination means (103, 107).
04, 105, 108 to 112) set an increase in a parameter relating to the injection amount. When the combustion state determination means (103, 107) does not determine stratified combustion, the parameter setting means (104, 105, 108). The control apparatus for a direct injection internal combustion engine according to claim 1, wherein the control unit sets an increase in a parameter relating to the intake air amount. 3. The torque control request determining means (100).
When the request for decreasing the output torque of the in-cylinder injection type internal combustion engine is determined by the above, when the combustion state determining means (103, 107) determines that the stratified combustion is determined, the parameter setting means (1)
04, 105, 108 to 112) set at least one of a decrease in the parameter relating to the injection amount and a retardation amount of the parameter relating to the injection timing and the ignition timing, and the stratified combustion by the combustion state determination means (103, 107). Is not determined, the parameter setting means (104, 105, 108 to 112) sets at least one of a decrease in a parameter relating to the intake air amount and a retard amount of a parameter relating to the ignition timing. The control device for a direct injection internal combustion engine according to claim 1 or 2.