JPH10153146A - Step motor type EGR control device - Google Patents

Abstract

(57) [Summary] In a step motor type EGR control device, E
Reduces the risk of torque fluctuation due to GR valve step-out,
Prevent deterioration of drivability. A fuel injection valve (11) is disposed around an inner wall surface of a cylinder head (4) near a first intake valve (6a) and a second intake valve (6b) of an engine (1), and fuel from the fuel injection valve (11) is directly supplied to a cylinder. It is injected into 1a. Exhaust gas recirculation (EG
R) The mechanism 51 includes an EGR passage 52 and an EGR valve 53.
And a step motor 54 for driving the EGR valve 53. When stratified charge combustion is being performed, the electronic control unit (ECU) 30 closes the EGR valve 53 when the actual torque fluctuation value is larger than a value obtained by adding a constant value to the target torque fluctuation value. Execute control. Then, when the EGR correction coefficient becomes a predetermined lower limit, it is determined that there is a possibility that the EGR valve 53 has stepped out, and initialization is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EGR control device, and more particularly, to an EGR system for recirculating a part of exhaust gas discharged from an internal combustion engine to intake air taken into the internal combustion engine.
The present invention relates to a step motor type EGR control device having a mechanism.

[0002]

2. Description of the Related Art In a conventionally used engine, fuel from a fuel injection valve is injected into an intake port, and a homogeneous mixture of fuel and air is supplied to a combustion chamber in advance. In such an engine, an intake passage is opened and closed by a throttle valve linked to an accelerator operation, and by this opening and closing, the amount of intake air supplied to a combustion chamber of the engine (consequently, a gas mixture in which fuel and air are homogeneously mixed). ) Is adjusted, thereby controlling the engine output.

[0003] However, in the technique based on the so-called homogeneous combustion described above, a large intake negative pressure is generated in accordance with the throttle operation of the throttle valve, and the pumping loss increases to lower the efficiency. On the other hand, by reducing the throttle of the throttle valve and supplying fuel directly to the combustion chamber, a combustible mixture is present near the ignition plug, and the air-fuel ratio of the portion is increased,
There is known a so-called "stratified combustion" technique for improving ignitability.

In this technique, when the engine is under a low load, the injected fuel is supplied unevenly around the spark plug, and the throttle valve is almost fully opened to perform stratified combustion. Thereby, the pumping loss is reduced, and the fuel efficiency is improved.

[0005] On the other hand, a technique called exhaust gas recirculation (EGR) has been known in which a part of exhaust gas discharged from an engine is recirculated to intake air taken into the engine. In this technology, an EGR passage is provided so as to communicate an exhaust passage and an intake passage of an engine, and the exhaust gas recirculation amount (E) is opened and closed in the middle of the passage.
An EGR valve for adjusting the GR amount is provided. Then, by controlling the step motor for driving the EGR valve, the opening degree of the EGR valve is controlled, and thus the EGR amount is controlled.

Then, the technology relating to the EGR control is
It is conceivable to apply the above-described stratified combustion.
However, in an engine equipped with such an EGR mechanism,
When stratified combustion is performed, the opening of the EGR valve is generally large, and the EGR amount is relatively large. And E
When a state where the GR amount is excessive occurs, the combustion state may be deteriorated, and the level of torque fluctuation may increase.

As a technique for solving such a problem, that is, a technique for suppressing a fluctuation in engine torque, for example, a technique disclosed in Japanese Patent Publication No. 3-66505 is known. In this technique, fluctuations in engine torque are detected based on fluctuations in engine rotation and the like. When the torque fluctuation is larger than a predetermined value, control is performed to close the EGR valve to reduce the exhaust gas recirculation amount (EGR amount). As described above, the torque fluctuation is suppressed by performing the control for reducing the EGR amount.

[0008]

However, the above technique has the following problems. That is, for some reason (for example, a decrease in the voltage supplied to the step motor,
Abnormality of the EGR valve body, external force due to vibration, etc.)
There may be a case where the valve opening changes irrespective of the target opening (this is called “step-out”). However,
In a step motor type EGR valve, its absolute opening cannot be detected. For this reason, when the step-out as described above occurs on the opening side, the target opening degree becomes
Even when the control lower limit value is reached, the actual opening of the EGR valve may remain larger than the target opening. As a result, a state in which the torque fluctuation is still large continues, and there is a possibility that drivability may be deteriorated.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an EGR mechanism for recirculating a part of exhaust gas discharged from an internal combustion engine to intake air taken into the internal combustion engine. In a step motor type EGR control device provided with a step motor type EGR control, even if an EGR valve loses synchronism, the risk of torque fluctuation due to the loss of synchronism can be reduced, and deterioration of drivability can be prevented. It is to provide a device.

[0010]

According to the first aspect of the present invention, an exhaust passage M2 and an intake passage M3 of an internal combustion engine M1 are connected to each other as shown in FIG. An exhaust gas recirculation passage M4 for recirculating a part of exhaust gas discharged from the internal combustion engine M1 to intake air taken into the internal combustion engine M1, and an exhaust gas recirculation passage M4; EGR valve M5 for adjusting the recirculation amount of the exhaust gas by opening and closing
A step motor M6 for driving the EGR valve M5; a torque fluctuation detecting means M7 for detecting a torque fluctuation of the internal combustion engine M1;
And a step-down motor M8 for controlling the opening of the EGR valve M5 to be small in order to suppress the torque fluctuation when the torque fluctuation detected by the step S7 is larger than a predetermined value. In the expression EGR control device, even when the control opening of the EGR valve M5 has reached a predetermined lower limit opening, if the torque fluctuation detected by the torque fluctuation detecting means M7 is still larger than a predetermined value, The gist is that the EGR valve M5 is provided with a step-out determining means M9 for determining that there is a possibility that a step-out has occurred.

According to a second aspect of the present invention, there is provided the step motor type EGR control device according to the first aspect,
Further, when the step-out determination means M9 determines that there is a possibility that step-out has occurred in the EGR valve M5, the opening of the EGR valve M5 is forcibly closed by a predetermined opening. The point is that the valve control means M10 is provided.

Further, according to the third aspect of the present invention, in the step motor type EGR control device according to the first aspect, there is a possibility that the EGR valve M5 has stepped out by the step out judgment means M9. If it is determined that there is, the gist is that initialization control means M11 for initializing the opening of the EGR valve M5 is provided.

According to a fourth aspect of the present invention, in the stepping motor type EGR control device according to the third aspect, when the opening of the EGR valve M5 is initialized by the initialization control means M11. The point is that the re-initialization is prohibited during the trip.

In addition, according to the invention described in claim 5, the step motor type EGR according to any one of claims 1 to 4 is provided.
The gist of the control device is that the internal combustion engine M1 can perform stratified combustion.

(Operation) According to the first aspect of the present invention,
As shown in FIG. 1, an EGR valve M5 provided in an exhaust gas recirculation passage M4 connecting the exhaust passage M2 and the intake passage M3 of the internal combustion engine M1 is driven by a step motor M6. Is adjusted. Further, the torque fluctuation detecting means M7 detects a torque fluctuation of the internal combustion engine M1, and if the detected torque fluctuation is larger than a predetermined value, the opening degree lowering control means M
8 controls the opening degree of the EGR valve M5 to be small. Thus, torque fluctuation is suppressed.

Now, for some reason, the opening of the EGR valve M5 may change irrespective of the target opening. In such a case, the EGR valve M5
Even if the control opening becomes the predetermined lower limit opening,
The torque fluctuation detected by the torque fluctuation detecting means M7 may still be larger than a predetermined value. On the other hand, in the present invention, in such a case, the step-out determination means M9 determines that the EGR valve M5 may have step-out. For this reason, it is possible to perform control different from the previous one by this determination.

According to the second aspect of the present invention, in addition to the effect of the first aspect of the present invention, it is possible that the step-out determination means M9 may cause a step-out of the EGR valve M5. If it is determined that the EGR valve M5 is present, the opening of the EGR valve M5 is forcibly closed by a predetermined opening by the valve closing control means M10. Therefore, even when step-out occurs as described above, it is possible to reduce the possibility of torque fluctuation.

Further, according to the third aspect of the present invention,
In addition to the operation of the invention described in claim 1, when the out-of-step determining means M9 determines that there is a possibility that the EGR valve M5 has lost step-out, the initialization control means M11 performs the operation. The opening of the EGR valve M5 is initialized. Therefore, the position of the EGR valve M5 is returned to the reference position, and thereafter, various controls based on the reference position can be performed again.

In addition, according to the invention described in claim 4,
In addition to the effect of the invention described in claim 3, when the opening of the EGR valve M5 is initialized by the initialization control means M11, the initialization is prohibited again during the trip. Therefore, the initialization is not performed a plurality of times during one trip, and the fluctuation and instability of the EGR amount can be suppressed.

In addition, according to the invention described in claim 5,
In addition to the operation of the invention described in claims 1 to 4, the internal combustion engine M1 can perform stratified combustion. As described above, when the stratified combustion is performed, the EGR amount increases, and the torque fluctuation tends to increase. Therefore, in such a case, the above-described operation is reliably achieved.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a step motor type EGR control device according to the present invention will be described below in detail with reference to the drawings.

FIG. 2 is a schematic configuration diagram showing a fuel injection control device of a direct injection type engine mounted on a vehicle in the present embodiment. The engine 1 as an internal combustion engine includes, for example, four cylinders 1a, and the combustion chamber structure of each of the cylinders 1a is shown in FIG. As shown in these figures,
The engine 1 includes a piston in a cylinder block 2, and the piston reciprocates in the cylinder block 2. The cylinder head 4 is located above the cylinder block 2.
Is provided, and a combustion chamber 5 is formed between the piston and the cylinder head 4. Further, in the present embodiment, four valves are arranged per cylinder 1a, and in the figure, the first intake valve 6a, the second intake valve 6b, the first intake port 7a, and the first intake port 7b in the figure. Two intake ports, a pair of exhaust valves as 8, and a pair of exhaust ports as 9 are shown.

As shown in FIG. 3, the first intake port 7a
Is composed of a helical intake port, and the second intake port 7
b consists of a straight port extending almost straight.
In addition, an ignition plug 10 is disposed at the center of the inner wall surface of the cylinder head 4. This spark plug 10 includes:
The igniter 12 via a distributor (not shown)
Is applied. And
The ignition timing of the ignition plug 10 is determined by the igniter 1
2 is determined by the output timing of the high voltage. Further, a fuel injection valve 11 as a fuel injection means is disposed around the inner wall surface of the cylinder head 4 near the first intake valve 6a and the second intake valve 6b. That is, in the present embodiment, the fuel from the fuel injection valve 11 is directly injected into the cylinder 1a.

As shown in FIG. 2, the first intake port 7a and the second intake port 7b of each cylinder 1a are respectively connected via a first intake path 15a and a second intake path 15b formed in each intake manifold 15. Connected to the surge tank 16. A swirl control valve 17 is arranged in each second intake passage 15b. These swirl control valves 17 are connected to, for example, a step motor 19 via a common shaft 18. The step motor 19 is controlled based on an output signal from an electronic control unit (hereinafter simply referred to as “ECU”) 30 described later. Instead of the step motor 19, a motor controlled according to the negative pressure of the intake ports 7a and 7b of the engine 1 may be used.

The surge tank 16 includes an intake duct 20
Is connected to the air cleaner 21 through the intake duct 20.
Inside, a throttle valve 23 which is opened and closed by a step motor 22 is provided. That is, the throttle valve 23 of the present embodiment is of a so-called electronic control type.
The throttle valve 23 is controlled to open and close by being driven based on the output signal from the controller. By opening and closing the throttle valve 23, the amount of intake air introduced into the combustion chamber 5 through the intake duct 20 is adjusted. In the present embodiment, the intake duct 20, the surge tank 16, the first intake path 15a and the second intake path 15b
Thus, an intake passage is formed.

In the vicinity of the throttle valve 23, a throttle sensor 25 for detecting the opening (throttle opening TA) is provided. An exhaust manifold 14 is connected to the exhaust port 9 of each cylinder.
Then, the exhaust gas after combustion is discharged to an exhaust duct forming an exhaust passage via the exhaust manifold 14.

Further, in the present embodiment, a known exhaust gas recirculation (EGR) mechanism 51 is provided. This E
The GR mechanism 51 includes an EGR passage 52 as an exhaust gas recirculation passage, an EGR valve 53 provided in the middle of the passage 52, and a step motor 54 for driving the EGR valve 53. The EGR passage 52 is provided so as to communicate between the intake duct 20 downstream of the throttle valve 23 and the exhaust duct. The EGR valve 53 has a built-in valve seat, valve body, and step motor (all not shown). The opening of the EGR valve 53 is
It varies due to the step motor 54 intermittently displacing the valve body with respect to the valve seat. And the EGR valve 5
When the valve 3 opens, a part of the exhaust gas discharged to the exhaust duct flows to the EGR passage 52. The exhaust gas is
It flows to the intake duct 20 via the EGR valve 53. That is, a part of the exhaust gas is recirculated into the intake air-fuel mixture by the EGR mechanism 51. At this time, the recirculation amount of the exhaust gas is adjusted by adjusting the opening degree of the EGR valve 53.

The above-described ECU 30 is formed of a digital computer, and is connected to a RAM (random access memory) 3 via a bidirectional bus 31.
2, a ROM (Read Only Memory) 33, a CPU (Central Processing Unit) 34 composed of a microprocessor, an input port 35 and an output port 36. In the present embodiment, the ECU 30 constitutes a torque fluctuation detection unit, a step-out determination unit, a valve closing control unit, and an initialization control unit.

Accelerator pedal 2 operated by the driver
4 is connected to an accelerator sensor 26A that generates an output voltage proportional to the amount of depression of the accelerator pedal 24,
Accelerator opening ACCP is detected by accelerator sensor 26A. The output voltage of the accelerator sensor 26A is
The signal is input to the input port 35 via the AD converter 37.
Similarly, the accelerator pedal 24 is provided with a fully-closed switch 26B for detecting that the depression amount of the accelerator pedal 24 is "0". That is, the fully closed switch 26B generates a signal of "1" as the fully closed signal when the depression amount of the accelerator pedal 24 is "0", and generates a signal of "0" otherwise. The output voltage of the fully closed switch 26B is also input to the input port 35.

The top dead center sensor 27 generates an output pulse when the first cylinder 1a reaches the intake top dead center, for example.
This output pulse is input to the input port 35. The crank angle sensor 28 has a crankshaft of 30 ° CA, for example.
An output pulse is generated each time the motor rotates, and the output pulse is input to the input port. In the CPU 34, the top dead center sensor 2
7 and the output pulse of the crank angle sensor 28, the engine speed NE is calculated (read).

Further, the rotation angle of the shaft 18 is detected by a swirl control valve sensor 29,
Thereby, the opening of the swirl control valve 17 is measured. The output of the swirl control valve sensor 29 is supplied to an input port 35 via an A / D converter 37.
Is input to

At the same time, the throttle sensor 25 detects the throttle opening degree TA. The output of the throttle sensor 25 is input to an input port 35 via an A / D converter 37.

In addition, in the present embodiment, an intake pressure sensor 61 for detecting the pressure (intake pressure PiM) in the surge tank 16 is provided. Further, a water temperature sensor 62 that detects the temperature of the cooling water of the engine 1 (cooling water temperature THW) is provided. Further, an oxygen sensor 63 for detecting the oxygen concentration OX in the exhaust gas is provided in the middle of the exhaust passage upstream of a three-way catalyst (not shown). The oxygen sensor 63 has a characteristic that the output voltage changes abruptly near the stoichiometric air-fuel ratio. In the present embodiment, the air-fuel ratio A / F is detected based on such characteristics. The outputs of these sensors 61, 62, 63 are also
The data is input to the input port 35 via the A / D converter 37.

In the present embodiment, the throttle sensor 25, the accelerator sensor 26A,
B, top dead center sensor 27, crank angle sensor 28, swirl control valve sensor 29, intake pressure sensor 61,
The water temperature sensor 62 and the oxygen sensor 63 constitute an operating state detecting means.

On the other hand, the output port 36 is connected to each of the fuel injection valves 11 and each of the step motors 1 via a corresponding drive circuit 38.
9, 22, the igniter 12 and the EGR valve 53 (step motor 54). And ECU3
Reference numeral 0 denotes a fuel injection valve 11, step motors 19 and 22, an igniter 12 (spark plug 10), and an EGR valve 53 based on signals from the sensors 25 to 29 and 61 to 63 in accordance with a control program stored in the ROM 33.
(Step motor 54) and the like are suitably controlled.

Next, a program relating to various controls according to the present embodiment in the step motor type EGR control device having the above configuration will be described with reference to flowcharts. FIG. 4 is a flowchart showing an "EGR amount / injection amount control routine" for controlling the EGR amount and the fuel injection amount by controlling the step motor 54, the fuel injection valve 11, and the like in the present embodiment. EC at an interruption every predetermined crank angle (for example, every “180 ° CA”)
This is executed by U30.

When the processing shifts to this routine, the ECU
30 first determines in step 101 whether the current operation mode FMODE is “0”. here,
The operation mode FMODE is set in a separate routine based on the current operation state. That is, the operation mode FMODE is set to "0" when stratified charge combustion is performed, the operation mode FMODE is set to "1" when homogeneous lean combustion is performed, and the operation mode FMODE is set to "2" when stoichiometric combustion is performed.
Are set respectively. And step 1
In 01, if the current operation mode FMODE is “0”, it is determined that stratified combustion is being performed, and the routine proceeds to step 102.

In step 102, based on the current engine speed NE and the fuel injection amount Qf, a target torque fluctuation value TFT0 is obtained by referring to a predetermined map (map 0 not shown).

Further, in step 103, it is determined whether or not the currently detected actual torque fluctuation value TF is larger than a value obtained by adding a constant value α (dead zone) to the above-described target torque fluctuation value TFT0. . Here, the actual torque fluctuation value TF is calculated based on the difference (ΔNE) between the detected engine speeds NE. Then, the actual torque fluctuation value TF is equal to the target torque fluctuation value TF.
If it is equal to or less than the value obtained by adding the constant value α to T0, the process proceeds to step 104 on the assumption that the torque fluctuation is not so large.

In step 104, it is determined whether or not the currently detected actual torque fluctuation value TF is smaller than a value obtained by subtracting a constant value α (dead zone) from the target torque fluctuation value TFT0. In this determination, if the actual torque fluctuation value TF is smaller than the value obtained by subtracting the constant value α from the target torque fluctuation value TFT0, step 1 is executed.
At 05, a value obtained by adding a predetermined correction term C0 to the previous EGR correction coefficient KEGR _i-1 is used as a new EGR correction coefficient KEGR (the EGR valve 53 (Corresponding to the required opening). Then, the subsequent processing ends once.
In the above determination, the actual torque fluctuation value TF is
If the value is not smaller than the value obtained by subtracting the constant value α from the target torque variation value TFT0, it is assumed that the actual torque variation value TF is within the constant value α with respect to the target torque variation value TFT0, and no processing is performed. Without this, the subsequent processing ends once.

On the other hand, if the actual torque fluctuation value TF is larger than the value obtained by adding the constant value α to the target torque fluctuation value TFT0 in step 103, it is determined that the torque fluctuation needs to be reduced. Move to 106. In step 106, a value obtained by subtracting a predetermined correction term C0 from the previous EGR correction coefficient KEGR _i-1 is set as a new EGR correction coefficient KEGR. As a result, the opening of the EGR valve 53 decreases, and the EG
The amount of R can be reduced.

Further, in the following step 107,
It is determined whether or not the current EGR correction coefficient KEGR has become equal to or less than a predetermined lower limit value KEGRMIN. The lower limit value KEGRMIN refers to a suitable value at which the EGR amount cannot be excessive if the EGR amount is reduced so far. If the current EGR correction coefficient KEGR is not less than the lower limit value KEGRMIN,
Thereafter, the processing is temporarily terminated. In contrast, the current EG
If the R correction coefficient KEGR is equal to or smaller than the lower limit value KEGRMIN, it is determined that there is a possibility that the EGR valve 53 has lost synchronism, and the routine proceeds to step 108.

In step 108, it is determined whether or not the initialization execution storage flag KEGRINTM is "0". Here, the initialization execution storage flag KEGRIN
TM is a flag indicating whether or not the initialization (initialization) of the EGR valve 53 has been executed during the trip in order to avoid the possibility of step-out. ".
Alternatively, it may be set to “0” in a separate routine after the end of the initialization control in the present embodiment. Then, the initialization execution storage flag KEGRI
If the NTM has already been set to "1", it is determined that there is no need to perform initialization again during the trip,
Thereafter, the processing is temporarily terminated.

If the initialization execution storage flag KEGRINTM is "0" in step 108, the process proceeds to step 109. In step 109, the initialization execution flag KEGRINT is set to "1". Thus, in a separate routine, the EGR valve 53
Is once closed to the reference position (fully closed butting position). At the same time, the initialization execution storage flag KEG
Set RINTM to "1". And the ECU 30
Terminates the subsequent processing once.

On the other hand, if the current operation mode FMODE is not "0" in step 101, the process proceeds to step 110. In step 110, it is determined whether or not the current operation mode FMODE is "1". If the current operation mode FMODE is not “1”, the current operation mode FMODE is “2”,
That is, assuming that stoichiometric combustion is being performed and the EGR amount is originally small, the subsequent processing is temporarily terminated without performing any processing. In addition, the current operation mode F
If MODE is "1", it is determined that homogeneous lean combustion is being performed, and the routine proceeds to step 111.

In step 111, a target torque variation value TFT1 is determined based on the current engine speed NE and the fuel injection amount Qf by referring to a predetermined map (Map 1 not shown).

Further, in the following step 112,
It is determined whether or not the currently detected actual torque fluctuation value TF is larger than a value obtained by adding a constant value β (dead zone) to the above-described target torque fluctuation value TFT1. When the actual torque fluctuation value TF is larger than the value obtained by adding the constant value β to the target torque fluctuation value TFT0, it is determined that the torque fluctuation needs to be reduced, and the process proceeds to step 113. In step 113, a value obtained by subtracting a predetermined correction term C1 from the previous fuel injection amount correction coefficient KQFi _-1 is set as a new fuel injection amount correction coefficient KQF.
As a result, the overall air-fuel ratio increases without the EGR amount fluctuating, and the torque fluctuation is suppressed.

If the actual torque fluctuation value TF is equal to or smaller than the value obtained by adding the constant value β to the target torque fluctuation value TFT1, it is determined that the torque fluctuation is not so large, and the routine proceeds to step 114.

In step 114, it is determined whether or not the currently detected actual torque fluctuation value TF is smaller than a value obtained by subtracting a constant value β (dead zone) from the target torque fluctuation value TFT1. In this determination, if the actual torque fluctuation value TF is smaller than the value obtained by subtracting the constant value β from the target torque fluctuation value TFT1, step 1
In step 15, a value obtained by adding a predetermined correction term C1 to the previous fuel injection amount correction coefficient KQFi _-1 to set the torque as small as possible is set as a new fuel injection amount correction coefficient KQF. Then, the subsequent processing ends once. If the actual torque fluctuation value TF is not smaller than the value obtained by subtracting the constant value β from the target torque fluctuation value TFT1, the actual torque fluctuation value TF becomes constant with respect to the target torque fluctuation value TFT1. Assuming that it is within the value β, the subsequent processing is temporarily ended without performing any processing.

Next, the operation and effect of this embodiment will be described. (A) In the present embodiment, when stratified charge combustion is performed, if the actual torque fluctuation value TF is larger than a value obtained by adding a constant value α to the target torque fluctuation value TFT0, the torque fluctuation is reduced. EG as what needs to be reduced
The closing control of the R valve 53 is executed. Here, the opening of the EGR valve 53 changes irrespective of the target opening due to some cause (for example, a decrease in the voltage supplied to the step motor 54, an abnormality in the EGR valve 53 main body, an external force due to vibration, etc.). In some cases. in this case,
The EGR correction coefficient KEGR is set to a predetermined lower limit KE.
It can be GRMIN or less. In such a case, in the present embodiment, it is determined that the EGR valve 53 may have lost synchronism. Further, in this case, the initialization execution flag KEGRINT is set to “1”, whereby the EGR valve 53 is once closed to the reference position (fully closed abutment position) in a separate routine. Therefore, it is possible to avoid a situation in which the target opening (control opening) of the EGR valve 53 remains fixed. As a result, it is possible to prevent drivability from deteriorating due to the continued state of large torque fluctuation.

(B) In this embodiment, since the position of the EGR valve 53 is returned to the reference position, various controls based on the reference position can be performed again thereafter. Therefore, controllability can be improved.

(C) Further, in the present embodiment, the EGR
When the opening of the valve 53 is initialized, the initialization is prohibited during the trip. Therefore, during one trip, the initialization is not performed a plurality of times.
Instability can be suppressed.

(D) In addition, in the present embodiment, when stratified combustion is being performed, the above-described initialization control is performed. As described above, when stratified combustion is performed, the EGR amount tends to increase and the torque fluctuation level tends to increase. Therefore, in such a case, the above-described operation and effect can be reliably achieved.

The present invention is not limited to the above embodiment, and may be configured as follows, for example. (1) In the above embodiment, the content of control is different between the case where the homogeneous lean combustion is executed and the case where the homogeneous combustion is executed.
The same control content may be used.

(2) In the above embodiment, the present invention is embodied in the in-cylinder injection type engine 1. However, the present invention is embodied in a so-called general stratified combustion or weak stratified combustion type. You may. For example, the intake ports 7a, 7b
Of the type which injects toward the back side of the umbrella portion of the intake valves 6a and 6b. Although a fuel injection valve is provided on the intake valves 6a and 6b side, a type in which fuel is injected directly into the cylinder bore (combustion chamber 5) is also included. Further, the present invention can also be embodied in an engine capable of performing lean combustion and stoichiometric combustion, which are higher concepts.

(3) In the above-described embodiment, the helical intake port is provided, and so-called swirl can be generated. However, it is not always necessary to generate swirl. Therefore, for example, the swirl control valve 17, the step motor 19, and the like in the above embodiment can be omitted.

(4) In the above embodiment, the present invention is embodied in the case of the gasoline engine 1 as the internal combustion engine. However, the present invention can be embodied in the case of a diesel engine or the like.

(5) In addition, in the above embodiment, the EG
When the R correction coefficient KEGR is equal to or smaller than the lower limit value KEGRMIN, the initialization (full-close contact) is performed, but it may be closed by a relatively large predetermined opening.

(6) In addition, a configuration may be adopted in which the dead zones α and β in the above embodiment are not considered.

[0060]

As described in detail above, according to the present invention,
In a stepper motor type EGR control device provided with an EGR mechanism for recirculating a part of exhaust gas discharged from an internal combustion engine to intake air taken into the internal combustion engine, even if the EGR valve loses synchronism, the synchronism is lost. Therefore, there is an excellent effect that the possibility of torque fluctuation due to the above can be reduced, and deterioration of drivability can be prevented.

[Brief description of the drawings]

FIG. 1 is a conceptual configuration diagram showing a basic concept of the present invention.

FIG. 2 is a step motor type EGR according to one embodiment;
It is a schematic structure figure showing a control device.

FIG. 3 is an enlarged sectional view showing a cylinder portion of the engine.

FIG. 4 is a flowchart showing an “EGR amount / injection amount control routine” executed by the ECU.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine, 11 ... Fuel injection valve as fuel injection means, 25 ... Throttle sensor which constitutes operating state detecting means, 26A ... Accelerator sensor which constitutes operating state detecting means, 26B ... Fully closed which constitutes operating state detecting means Switch, 27 ... Top dead center sensor constituting operating state detecting means,
28 ... Crank angle sensor constituting operating state detecting means,
29: a swirl control valve sensor constituting the operating state detecting means; 30: an EC constituting the torque fluctuation detecting means, the step-out determining means, the valve closing control means, and the initialization controlling means
U, 61... An intake pressure sensor constituting operating state detecting means;
62: a water temperature sensor constituting an operating state detecting means; 63 ...
An oxygen sensor which constitutes an operation state detecting means.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02D 41/02 301 F02D 41/02 301F G01M 15/00 G01M 15/00 Z

Claims (5)

[Claims] An exhaust gas is provided so as to communicate an exhaust passage and an intake passage of an internal combustion engine, and recirculates a part of exhaust discharged from the internal combustion engine to intake air taken into the internal combustion engine. A recirculation passage; an EGR valve provided in the exhaust gas recirculation passage for adjusting the amount of recirculation of the exhaust gas by opening and closing; a step motor for driving the EGR valve; and a torque of the internal combustion engine. Torque fluctuation detecting means for detecting fluctuation, and when the torque fluctuation detected by the torque fluctuation detecting means is larger than a predetermined value, controlling the opening of the EGR valve so as to reduce the torque fluctuation. Motor type EG provided with opening degree reduction control means
In the R control device, even when the control opening of the EGR valve has reached a predetermined lower limit opening, if the torque fluctuation detected by the torque fluctuation detecting means is still larger than a predetermined value, the EGR valve A step motor type EGR control device, further comprising a step-out determining means for determining that step-out may have occurred. 2. The step motor type EG according to claim 1.
In the R control device, if the out-of-step determining unit determines that there is a possibility that the out-of-step of the EGR valve has occurred, the opening of the EGR valve is forcibly closed by a predetermined amount. A step motor type EGR control device characterized by comprising valve closing control means. 3. The step motor type EG according to claim 1,
The R control device further includes initialization control means for initializing the opening degree of the EGR valve when the out-of-step determination means determines that there is a possibility that the EGR valve has lost synchronization. A step motor type EGR control device, characterized in that: 4. The EGR control device according to claim 1, wherein
4. The step motor type EGR control device according to claim 3, wherein when the opening of the valve is initialized, reinitialization is prohibited during the trip. 5. A step motor type EGR control device according to claim 1, wherein said internal combustion engine is capable of performing stratified combustion.