JP2001193573A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine capable of improving responsiveness in supercharging pressure control and securing safety in supercharging pressure control and EGR control in the case that the internal combustion engine is in transient operation range when controlling both EGR volume and supercharging pressure and thereby to improve exhaust gas characteristics and operativity. SOLUTION: This control device 1 for EGR feedback control and supercharging pressure open control in the internal combustion engaging 3 having a supercharger 5a with an adjustable vane 5f sets a duty ratio (duty) of a vane opening control valve 5c from a transient operation range map (Step 2) according to an engine speed Ne and an intake air volume Q when the internal combustion engine 3 is in transient operation range (Step 1 is YES).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an internal combustion engine with a supercharger for controlling both a supercharging pressure and a recirculation amount of exhaust gas to an intake system.

[0002]

2. Description of the Related Art Conventionally, there has been known a diesel engine with a supercharger which performs EGR for returning exhaust gas to an intake system (for example, JP-A-6-58173). The diesel engine is operated by controlling the fuel injection amount while keeping the amount of air taken into the combustion chamber constant without restricting the intake air. In such an EGR control device for an engine, an actual intake air amount sucked as fresh air is detected by an air flow sensor,
The valve opening of the EGR control valve is feedback controlled so that the detected value becomes the target intake air amount.

Further, as a supercharging pressure control device for an engine having a turbocharger with a variable vane, a supercharging pressure sensor for detecting a supercharging pressure and an electromagnetic actuator for controlling the opening degree of the variable vane by driving the variable vane. There is also known an apparatus that performs feedback control of the opening degree of the variable vane so that the actual boost pressure detected by the boost pressure sensor becomes the target boost pressure.

[0004]

When the above-described diesel engine EGR control device and the supercharging pressure control device are combined, if the supercharging pressure is feedback-controlled when the engine is in the transient operation range, the response is low. Thus, it takes time for the actual boost pressure to reach the target boost pressure. For this reason, especially when the vehicle is in an acceleration state, the rise of the engine output is delayed, thereby deteriorating the acceleration performance.

Further, since the intake air amount is controlled by two control amounts, that is, the valve opening degree of the EGR control valve and the opening degree of the variable vane, the two control amounts influence each other, so that the EGR control and the excessive In some cases, it may not be possible to stably perform the supply pressure control. For example, EGR
When the valve opening of the control valve changes, the supercharging pressure changes due to the effect. On the other hand, even if the opening degree of the EGR control valve is constant, the EGR amount fluctuates with the fluctuation of the supercharging pressure in the intake pipe. This is because the recirculation operation of the exhaust gas in the EGR control utilizes a differential pressure between the upstream side and the downstream side of the EGR control valve, which is generated in the EGR pipe due to the supercharging pressure in the intake pipe. As a result, when the supercharging pressure control becomes unstable, the supercharging pressure is affected by fluctuations in the supercharging pressure, so that E
GR control also becomes unstable, resulting in deterioration of exhaust gas characteristics and operability.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and when controlling both the EGR amount and the supercharging pressure, the response of the supercharging pressure control when the internal combustion engine is in a transient operation region. It is an object of the present invention to provide a control device for an internal combustion engine, which can enhance the operability and can secure the stability of the supercharging pressure control and the EGR control, thereby improving the exhaust gas characteristics and the operability. .

[0007]

In order to achieve this object, according to the first aspect of the present invention, the amount of exhaust gas recirculated to the intake passage (intake pipe 8) is feedback-controlled and the supercharging pressure P is reduced. A control device 1 for an internal combustion engine 3 with a supercharger 5a for controlling a supercharging pressure control valve (a vane opening control valve 5c) for controlling a supercharging pressure P, and an operating state (engine speed Ne, suction Operating state detecting means (ECU 2, crank angle sensor 20, air flow sensor 21) for detecting air amount Q), and determining means (ECU 2, step 1) for determining whether internal combustion engine 3 is in a transient operating region. When the determination means determines that the vehicle is in the transient operation range (when the determination result in step 1 is YES), the supercharging pressure control valve (the vane opening control valve 5c) according to the detected operation state.
(ECU2, step 2) for setting the valve opening VL (setting the duty ratio duty).

According to this control device for an internal combustion engine, when the determination means determines that the internal combustion engine is in the transient operation range, the valve opening setting means responds to the operation state detected by the operation state detection means. The supercharging pressure control valve opens and controls the supercharging pressure according to the set valve opening. As described above, in the transient operation region, the supercharging pressure is not controlled by feedback control but is controlled by the open state in accordance with the operation state, so that the exhaust gas recirculation amount (EGR)
, The stability of the boost pressure control can be appropriately secured. Further, by performing the open control, it is possible to improve the responsiveness of the boost pressure control in the transient operation region, particularly, the acceleration performance. Further, as described above, the stability of the supercharging pressure control in the transient operation region is appropriately secured, so that E
The stability of GR control can be ensured. Thereby, the exhaust gas characteristics can be improved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A control device for an internal combustion engine according to one embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of an internal combustion engine of the present embodiment, and FIG. 2 shows a schematic configuration of a control device. As shown in FIG. 2, the control device 1 includes an ECU 2 (operating state detecting means, discriminating means, valve opening setting means), and the ECU 2 is provided with an internal combustion engine 3 (hereinafter referred to as "engine 3") shown in FIG. ), The control of the supercharging pressure P and the control of the recirculation amount of the exhaust gas (EGR control) are performed as described later. The control device 1 includes a fuel injection control mechanism 4, a supercharging pressure control mechanism 5, an EGR control mechanism 6, a swirl control mechanism 7, and the like, and details thereof will be described later.

The engine 3 is an in-line four-cylinder diesel engine having a cylinder 3a and a piston 3b (only one is shown). A combustion chamber 3d is formed between the piston 3b and the cylinder head 3c. ing.

The fuel injection control mechanism 4 includes a fuel injection valve 4a
(Hereinafter referred to as “injector 4a”) and a fuel pump 4b. The injector 4a is attached to the cylinder head 3c so as to face the combustion chamber 3d, and is connected to the fuel pump 4b via the fuel pipe 4c. The fuel pump 4b is an accumulator type fuel pump, and is connected to a fuel tank 4d via a fuel pipe 4c. The fuel pump 4b supplies the pressurized fuel to the injector 4a at an injection timing according to a drive signal from the ECU 2.

The crankshaft 3e of the engine 3
Is provided with a magnet rotor 20a.
The magnet rotor 20a is provided with a crank angle sensor 2 together with an MRE (magnetoresistive element) pickup 20b.
0 (operation state detecting means). The crank angle sensor 20 converts a CRK signal, which is a pulse signal, into a predetermined crank angle (for example,
Output every 1 ご と). The ECU 2 calculates an engine speed Ne (a parameter representing an operating state of the internal combustion engine) of the engine 3 based on the CRK signal.

Further, an air cleaner 9 and an air flow sensor 21 (operating state detecting means) are attached to the intake pipe 8 (intake passage) of the engine 3 in order from the upstream side. The air flow sensor 21 is arranged close to the air cleaner 9 and is constituted by, for example, a hot wire air flow meter. The airflow sensor 21 detects an intake air amount Q (a parameter representing an operation state of the internal combustion engine) in accordance with a change in the resistance value of the hot wire (platinum wire), and outputs a detection signal to the ECU.
Send to 2.

The supercharging pressure control mechanism 5 includes an intake pipe 8
Is disposed downstream of the airflow sensor 21. The supercharging pressure control mechanism 5 includes a supercharger 5a integrally attached to the intake pipe 8 and the exhaust pipe 10, an actuator 5b connected to the supercharger 5a, and a vane opening control valve connected to the actuator 5b. 5c and the like.

The supercharger 5a is a so-called turbocharger, and has a turbine rotor 5d and a housing 5e. The turbine rotor 5d is formed by integrally assembling a compressor blade, a turbine blade, and the like. The turbine rotor 5d is rotatably attached to a housing 5e that forms the intake pipe 8 and the exhaust pipe 10 while being incorporated therein. When the turbine blades of the turbine rotor 5d are driven to rotate by the exhaust gas in the exhaust pipe 10, the supercharger 5a also drives the compressor blades integral with the turbine blades to drive the intake air in the intake pipe 8. A pressurizing operation is performed.

The supercharger 5a includes a plurality of variable vanes 5
f (only two are shown). These variable vanes 5f are for changing the supercharging pressure P generated by the supercharger 5a, and are rotatably attached to a wall of a portion of the housing 5e that houses the compressor blade. Each variable vane 5f is mechanically connected to an actuator 5b, and when driven by the actuator 5b, its opening (hereinafter referred to as “vane opening”) changes. Thereby, the supercharging pressure P is changed by changing the amount of intake air flowing from the compressor blade to the downstream side.

On the other hand, the actuator 5b is of a diaphragm type operated by a negative pressure, and is connected to a negative pressure pump 12 through a vane opening control valve 5c and a negative pressure pipe 11. The negative pressure pump 12 is connected to a drive shaft (not shown) of the engine 3.
During this operation, a negative pressure is generated by being driven by this, and the negative pressure is supplied to the vane opening control valve 5c. The vane opening control valve 5c is an electromagnetic valve,
(See FIG. 2). The vane opening control valve 5c changes the negative pressure supplied to the actuator 5b by changing the valve opening VL in accordance with a drive signal from the ECU 2. Thereby, the vane opening control valve 5c controls the supercharging pressure P by changing the vane opening via the actuator 5b.

A supercharging pressure sensor 22 is attached to the intake pipe 8 downstream of the supercharger 5a. The supercharging pressure sensor 22 includes a semiconductor pressure sensor or the like, detects a supercharging pressure P (absolute pressure) in the intake pipe 8, and sends a detection signal (detected supercharging pressure Pact) to the ECU 2. Further, a portion of the intake pipe 8 on the downstream side of the supercharging pressure sensor 22 is an intake manifold 8a including one collecting portion and four branch portions branched therefrom. Further, the pipeline of the intake manifold 8a is divided into a swirl pipeline 8b and a bypass pipeline 8c from the collecting portion to each branch portion, and these pipelines 8b and 8c are respectively connected to the combustion chamber via two intake ports. It communicates with 3d.

A swirl valve 7a of the swirl control mechanism 7 is disposed in the swirl pipe 8b. The swirl control mechanism 7 generates swirl in the swirl pipe 8b by changing the opening of the swirl valve 7a, and thereby stirs the air-fuel mixture in the combustion chamber 3d. Further, the swirl control mechanism 7 includes an actuator 7
b and a swirl control valve 7c. The actuator 7b and the swirl control valve 7c are configured similarly to the actuator 5b and the vane opening control valve 5c of the supercharging pressure control mechanism 5, respectively. That is,
The swirl control valve 7c is an electromagnetic valve, is electrically connected to the ECU 2 (see FIG. 2), and supplies a negative pressure to the diaphragm type actuator 7c according to a drive signal from the ECU 2. Thereby, the opening of the swirl valve 7a is controlled.

On the other hand, the EGR control mechanism 6 includes an intake pipe 8
And an EGR pipe 6a connected between the exhaust pipe 10 and an EGR control valve 6b for opening and closing the EGR pipe 6a. One end of the EGR pipe 6a is open to the gathering portion of the exhaust manifold 10a of the exhaust pipe 10, and the other end is open to the portion of the bypass manifold 8c of the gathering portion of the intake manifold 8a. Further, the EGR control valve 6b
Is a linear solenoid valve, and the valve lift L changes linearly between a maximum lift Lmax and a minimum lift Lmin in response to a drive signal from the ECU 2, thereby changing the opening of the EGR pipe 6a. Let it. Furthermore, EGR
A valve lift amount sensor 23 is attached to the control valve 6b. This valve lift sensor 23 is provided by the ECU
2 (see FIG. 2) to detect the actual valve lift L of the EGR control valve 6b,
The detection signal is sent to the ECU 2.

Further, a catalyst device 13 for purifying exhaust gas is mounted downstream of the supercharger 5a of the exhaust pipe 10. Further, an accelerator opening sensor 24 (see FIG. 2) is attached to an accelerator pedal (not shown) of the engine 3. This accelerator opening sensor 2
The ECU 4 detects an accelerator pedal opening θap (hereinafter referred to as “accelerator opening θap”) and outputs a detection signal to the ECU 2.
Send to

On the other hand, the ECU 2 comprises a CPU, a RAM, an RO
It is composed of a microcomputer including an M and an I / O interface (both not shown).
The detection signals of the sensors 20 to 24 input to the ECU 2 are input to the CPU after being subjected to A / D conversion and shaping by the input interface. The CPU determines whether or not the vehicle is in an operating region in which EGR feedback control is to be performed, according to these input signals. When the vehicle is in an operation region where EGR feedback control is to be performed, for example, in a transient operation region, the air flow sensor 21
Is the target intake air amount Qcm
d, the valve lift amount L of the EGR control valve 6b
Feedback control. When the EGR feedback control is performed, as described below, the duty control of the vane opening control valve 5c is performed to open-control the vane opening of the variable vane 5f when in the transient operation region. That is, when the vehicle is in the transient operation region, the EGR feedback control is performed and the open control of the supercharging pressure P is performed. On the other hand, when it is not in the operation region where the EGR feedback control is to be performed, the valve opening VL of the vane opening control valve 5c is feedback-controlled so that the detected supercharging pressure Pact becomes the target supercharging pressure P0. That is, feedback control of the supercharging pressure P is performed.

FIG. 3 is a flowchart showing an operation region discrimination process executed when the EGR amount is feedback-controlled and the supercharging pressure P is open-controlled. This processing is performed for a predetermined time (for example, 100 msec) by setting a timer.
An interrupt is executed every c).

In this process, first, in step 1 (S in the figure)
Abbreviated as 1. The same applies to the following).
4 is the current value θap (n) of the accelerator opening θap detected
Is read, and the current value θap (n) and the previous value θap
It is determined whether or not the absolute value of the deviation from (n-1) is equal to or greater than a first predetermined value K1.

When the result of the determination in step 1 is YES, that is, when | θap (n) −θap (n−1) | ≧ K1, it is determined that the engine 3 is in the acceleration region of the transient operation region, and step 2 is performed. Proceed to. In step 2,
FIG. 4 shows an example of the transient operation region map with the duty ratio d.
uty calculation map and the vane opening control valve 5c
Is calculated. Specifically, the duty ratio duty is obtained by performing an interpolation calculation using the current calculated value of the engine speed Ne and the current detected value of the intake air amount Q with reference to such a transient operation region map. Is calculated. Thereafter, the present process ends.

As shown in the figure, in the transient operation area map, the duty ratio duty (%) is set to increase as the engine speed Ne increases or the intake air amount Q increases. This is because when the engine speed Ne or the intake air amount Q is large, that is, when the operating load is large, it is necessary to generate a large supercharging pressure P in order to secure a large engine output.

On the other hand, if the decision result in the step 1 is NO, that is, | θap (n) −θap (n−1) | <K
In the case of 1, it is determined that the engine 3 is not in the transient operation region,
Proceed to step 3. In step 3, whether the value obtained by dividing the difference between the detected supercharging pressure Pact, which is the detection value of the supercharging pressure sensor 22, and the target supercharging pressure P0 by the target supercharging pressure P0 is equal to or less than a second predetermined value K2. It is determined whether or not.

If the decision result in the step 3 is YES, that is, if (Pact-P0) / P0≤K2, it is determined that the engine 3 is in a steady operation region, and the process proceeds to a step 4. In step 4, the steady operation region map shown in FIG. 5 is set as the duty ratio duty calculation map, and the duty ratio duty of the vane opening control valve 5c is calculated. Also in step 4, similarly to step 2, the duty ratio duty is obtained by interpolating the current operation value of the engine speed Ne and the current detection value of the intake air amount Q with reference to the steady operation region map. It is calculated by performing an operation. Thereafter, the present process ends.

As shown in the figure, in this steady operation region map, as in the transient operation region map, the duty ratio duty is set to be larger as the engine speed Ne or the intake air amount Q is larger. ing. Also, compared with the transient operation region map, the duty ratio du
ty is set to be smaller than the value of the transient operation region map with respect to the engine speed Ne and the intake air amount Q. This is because a larger engine output is not required in the steady operation region than in the transient operation region.

On the other hand, if the decision result in the step 3 is NO, that is, if (Pact-P0) / P0> K2, it is determined that neither the transient operation region nor the steady operation region is present, and this processing is ended. In this case, in a duty ratio correction process (not shown), the basic map value dutyM of the duty ratio is changed to this value (Pact-P0).
/ P0, the duty ratio du
ty is calculated.

The duty ratio of the vane opening control valve 5c is controlled by the duty ratio duty calculated by the ECU 2 as described above. As a result, the open control of the supercharging pressure P is performed by the open control of the vane opening of the variable vane 5f.

According to the control device 1 of the present embodiment as described above, when it is determined in step 1 that the engine 3 is in the transient operation region, the transient state is determined according to the engine speed Ne and the intake air amount Q. The duty ratio duty of the vane opening control valve 5c is calculated from the operation region map. The duty control of the vane opening control valve 5c is performed based on the calculated duty ratio duty, whereby the open control of the supercharging pressure P is performed. As described above, in the transient operation region, the supercharging pressure P is controlled not by the feedback control but by the open control. Therefore, it is possible to appropriately secure the stability of the supercharging pressure control without being affected by the EGR feedback control. it can. Further, by performing the open control, it is possible to improve the responsiveness of the boost pressure control in the transient operation region, particularly, the acceleration performance. Further, as described above, the stability of the supercharging pressure control in the transient operation region is appropriately secured, so that the stability of the EGR control can be secured. Thereby, the exhaust gas characteristics can be improved.

In the above embodiment, an example in which the control device 1 is applied to a diesel engine has been described. However, the control device 1 of the present invention is not limited to this, and may be applied to a gasoline engine. Further, the supercharger is not limited to the turbocharger, but may be a mechanical supercharger such as a supercharger. Furthermore, the supercharging pressure P generated by the supercharger
Is not limited to the variable vanes, but may be any configuration that can change the supercharging pressure P, such as a wastegate valve.

[0034]

As described above, according to the control apparatus for an internal combustion engine of the present invention, when controlling both the EGR amount and the supercharging pressure, the supercharging pressure control is performed when the internal combustion engine is in a transient operation region. And the stability of the supercharging pressure control and the EGR control can be secured, whereby the exhaust gas characteristics and the operability can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an internal combustion engine to which a control device according to one embodiment of the present invention is applied.

FIG. 2 is a block diagram illustrating a schematic configuration of a control device.

FIG. 3 is a flowchart illustrating a procedure of an operation area determination process.

FIG. 4 is a diagram illustrating an example of a transient operation region map for calculating a duty ratio duty of a vane opening control valve.

FIG. 5 is a diagram showing an example of a steady operation region map for calculating a duty ratio duty of a vane opening control valve.

[Explanation of symbols]

Reference Signs List 1 control device 2 ECU (operating state detecting means, discriminating means, valve opening setting means) 3 internal combustion engine 5a supercharger 5c vane opening control valve (supercharging pressure control valve) 8 intake pipe (intake passage) 20 crank angle Sensor (Operating state detecting means) 21 Air flow sensor (Operating state detecting means) Ne Engine speed (Parameter indicating operating state) P Supercharging pressure duty Duty ratio (Set value of valve opening of supercharging pressure control valve) Q Intake Air volume (parameter indicating operating condition) VL Valve opening of vane opening control valve (valve opening of boost pressure control valve)

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Koji Ishimoto, 1-4-1 Chuo, Wako-shi, Saitama Prefecture Inside Honda R & D Co., Ltd. (72) Seiichi Hosokai 1-4-1, Chuo, Wako-shi, Saitama Prefecture Inside the Honda R & D Co., Ltd. (72) Inventor Masaki Nishio 1-4-1 Chuo, Wako-shi, Saitama F-term inside the Honda R & D Co., Ltd. (reference) 3G005 DA02 EA15 FA04 GB24 GD11 JA24 JA45 JA51 JB02 3G062 AA01 AA05 CA06 EA12 GA01 GA06 GA14 GA21 3G084 AA01 DA05 FA07 FA12 FA33 FA37

Claims (1)

[Claims] 1. A control device for an internal combustion engine with a supercharger for controlling a supercharging pressure while controlling a recirculation amount of exhaust gas recirculated to an intake passage, wherein the supercharging controls the supercharging pressure. Pressure control valve; operating state detecting means for detecting an operating state; determining means for determining whether or not the internal combustion engine is in a transient operating area; and when the determining means determines that the engine is in the transient operating area. And a valve opening setting means for setting a valve opening of the supercharging pressure control valve in accordance with the detected operating state.