JPH1162718A - Exhaust circulating device, and driving method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of combustion stability or the like caused by response lag in stopping of exhaust circulation at the time of acceleration ranging from stratified charge combustion region under exhaust circulation to homogeneous stoichiometric charge combustion region through homogeneous lean combustion where the exhaust circulation is not conducted, in an in-cylinder injection type engine. SOLUTION: This exhaust circulation device is provided with a surge tank 24b forming one part of an intake passage, exhaust circulation passages 31, 32, 33 for circulating one part of exhaust in an exhaust manifold 30 to the intake passage, an EGR valve 34 for regulating a flow rate of recalculated exhaust, and an electromagnetic solenoid 45 for driving the valve. In this case, the first intake port 32a for taking the exhaust in from the recirculation passage 32 to the surge tank and the second intake port 33a for taking the exhaust in from the recirculation passage 33 to the intake passage 24a are provided in the downstream in the circulating direction of a EGR valve position, the first opening and closing valve 37 for the first intake port and a step mortor 38 are also provided, and the EGR valve and the first opening and closing valve are controlled by a control unit 39 in response to operation coditions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas recirculation device for recirculating a part of exhaust gas of a spark ignition type internal combustion engine to intake air and a method of driving the same, and more particularly, to an in-cylinder in which fuel is directly injected into a cylinder and burned. The present invention relates to an exhaust gas recirculation device applied to an injection type internal combustion engine and a driving method thereof.

[0002]

2. Description of the Related Art A conventional in-cylinder injection type internal combustion engine (hereinafter referred to as an engine) is disclosed in, for example, Japanese Patent Application Laid-Open No. H8-312402.
And Japanese Patent Application Laid-Open No. 8-313399.

In this engine, as shown in FIG. 16, an intake manifold 4 forming a part of an intake passage for guiding air to a combustion chamber 3 defined by a lower surface of a cylinder head 1 and an upper surface of a piston 2, and the like, An intake valve 5 for opening and closing an open end of an intake port 1a of the cylinder head 1 to which an intake pipe 4a of the manifold 4 is connected, and a rotatably provided at a position upstream of a surge tank 4b of the intake manifold 4. A throttle valve 6 interlocked with an accelerator pedal (not shown); an exhaust valve 9 disposed on the opposite side of the intake valve 5 with the ignition plug 8 interposed therebetween to open and close an open end of an exhaust port 1b of the cylinder head 1; An exhaust manifold 10 connected to the exhaust manifold 1b for guiding exhaust gas to the outside;
A high-pressure fuel injection valve 11 attached to the cylinder head 1 and injecting fuel directly into the cylinder, an exhaust outlet 10a formed in the exhaust manifold 10, and an exhaust intake 4c formed immediately upstream of the surge tank 4b. An exhaust gas recirculation passage 12 is connected to recirculate a part of the exhaust gas to the intake air, and an exhaust gas recirculation control valve 13 is provided in the exhaust gas recirculation passage 12 to adjust the flow rate of the recirculated exhaust gas. The exhaust gas recirculation passage 12 and the exhaust gas recirculation control valve 13 constitute an exhaust gas recirculation device of the engine.

[0004] In the above-described in-cylinder injection type engine, the fuel is highly stratified without diffusing the fuel in the low load operation region, and the air-fuel ratio is 3
Ultra-lean combustion of 0 to 40 is realized to improve fuel efficiency, etc. In addition, high-output operation is achieved by uniformly diffusing and mixing fuel in a high-load operation region, and low-load operation is performed by performing exhaust gas recirculation. The reduction of NOx in the region or the improvement of fuel efficiency in the high load operation region and the like are aimed at.

In the above engine, for example, a stratified combustion region A or a homogeneous stoichiometric combustion region C where exhaust gas recirculation is performed is directed to a homogeneous lean combustion region B where exhaust gas recirculation is not performed based on an operation map as shown in FIG. Or when the combustion region is switched from the stratified combustion region A to the homogeneous stoichiometric combustion region C or from the homogeneous stoichiometric combustion region C to the stratified combustion region A so as to pass through a homogeneous lean combustion region B in which exhaust gas recirculation is not performed. Even when the exhaust gas recirculation control valve 13 is closed at the position of the combustion switching line in order to stop the exhaust gas recirculation, as shown in FIG. The amount of recirculated exhaust gas already taken in the pipe 4a will remain. Therefore, as shown in FIG. 19, due to the recirculated exhaust gas present at the time of switching the combustion, the combustion stability in the homogeneous lean combustion region B where the exhaust gas recirculation is not performed is deteriorated.

Therefore, in order to improve the deterioration of the combustion stability, a method of delaying the combustion switching time until the residual recirculated exhaust gas completely disappears has been proposed as disclosed in Japanese Patent Application Laid-Open No. H8-312402. is there.

There is also a method of enriching the air-fuel ratio in the homogeneous lean combustion region at the time of switching the combustion so that even if the recirculated exhaust gas remains, the combustion is not affected.

[0008]

However, the method of delaying the switching timing of the combustion can be employed at the time of deceleration without a request for increasing the torque, but at the time of rapid acceleration with a request for increasing the torque, that is, in the stratified combustion region. When it is necessary to switch the combustion from A to the homogeneous lean combustion region B or to the homogeneous stoichiometric combustion region C after passing through the homogeneous lean combustion region B, the accelerated driving performance deteriorates.

Further, in the method of enriching the air-fuel ratio in the homogeneous lean combustion region B, the torque step suddenly increases depending on the degree of the air-fuel ratio enrichment, which may cause deterioration in drivability.
In order to absorb this torque step, it is conceivable to retard the ignition timing to respond.However, when exhaust gas recirculation is performed, the deterioration of combustion due to the retardation of the ignition timing appears early. Cannot be retarded by a necessary amount, and it is difficult to eliminate the torque step.

The present invention has been achieved in view of the above-mentioned problems of the prior art, and has as its object the case where the operation shifts from an operation region in which exhaust gas recirculation is performed to an operation region in which exhaust gas recirculation is not performed. Another object of the present invention is to provide an exhaust gas recirculation device and a driving method thereof that can reduce the amount of remaining recirculated exhaust gas as much as possible to prevent the deterioration of combustion stability and achieve high output with low fuel consumption as a whole.

[0011]

According to a first aspect of the present invention, there is provided an exhaust gas recirculation device which is located in the middle of an intake passage extending from an outside air inlet to an intake valve which is opened and closed by an intake valve. , An exhaust gas recirculation passage for recirculating a part of the exhaust gas in the exhaust gas passage to the intake passage, an exhaust gas recirculation control valve for opening and closing the exhaust gas recirculation passage to regulate the flow rate of the recirculated exhaust gas, and an exhaust gas recirculation control. An exhaust gas recirculation device including a control valve driving means for driving a valve, wherein the exhaust gas recirculation device is positioned at a position downstream of the exhaust gas recirculation control valve in the exhaust gas recirculation direction and is directed from the exhaust gas recirculation passage toward the surge tank. And a second intake opening from the exhaust gas recirculation passage to the intake passage between the surge tank and the intake valve port for introducing recirculated exhaust gas. And access opening, a first on-off valve for opening and closing the first inlet, first to drive the first on-off valve
A drive means and a control means for controlling the drive of the exhaust gas recirculation control valve and the first on-off valve by the control valve drive means and the first drive means according to the operating conditions of the engine are provided.

[0012] The exhaust gas recirculation device according to claim 2 of the present invention comprises:
A surge tank which is located in the middle of an intake passage extending from an outside air introduction port to an intake valve opening opened and closed by an intake valve and forms a part of the intake passage, and a part of exhaust gas in the exhaust passage is returned to the intake passage. An exhaust gas recirculation passage, an exhaust gas recirculation control valve that opens and closes the exhaust gas recirculation passage to adjust the flow rate of the recirculated exhaust gas,
A control valve driving means for driving an exhaust gas recirculation control valve, the exhaust gas recirculation control valve being located at a position downstream of the exhaust gas recirculation control valve in the exhaust gas recirculation direction from the exhaust gas recirculation passage. A first intake opening toward the tank and capable of taking in recirculated exhaust gas, and a second intake opening opening from the exhaust gas recirculation passage toward the intake passage between the surge tank and the intake valve port and capable of taking in recirculated exhaust gas; A first on-off valve and a second on-off valve for opening and closing the first and second intake ports, respectively, and a first driving means and a second driving means for driving the first and second on-off valves, respectively. Control for controlling driving of the exhaust gas recirculation control valve, the first on-off valve, and the second on-off valve by the control valve driving unit, the first driving unit, and the second driving unit in accordance with operating conditions of the engine. It has a configuration which is provided and the stage, the.

According to a third aspect of the present invention, there is provided a method of driving an exhaust gas recirculation device, wherein a part of an intake passage is formed in a middle of an intake passage extending from an outside air inlet to an intake valve which is opened and closed by an intake valve. Drives a surge tank, an exhaust gas recirculation passage that recirculates part of the exhaust gas in the exhaust gas passage into the intake passage, an exhaust gas recirculation control valve that opens and closes the exhaust gas recirculation passage to adjust the flow rate of the recirculated exhaust gas, and an exhaust gas recirculation control valve. Control valve driving means, and a first intake port and an exhaust port located at a position downstream of the exhaust gas recirculation control valve in the exhaust gas recirculation direction and open from the exhaust gas recirculation passage toward the surge tank and capable of taking in recirculated exhaust gas. A second intake opening from the return passage to the intake passage between the surge tank and the intake valve opening and capable of taking in the return exhaust gas, and a first opening and closing the first intake.
Opening / closing valve, first driving means for driving the first opening / closing valve, and control means for controlling driving of the exhaust gas recirculation adjusting valve and the first opening / closing valve by the control valve driving means and the first driving means according to the operating conditions of the engine. A driving method for the exhaust gas recirculation device, comprising: opening an exhaust gas recirculation control valve and opening the first on-off valve in an operation region where exhaust gas recirculation is performed; When the operation shifts to the operation region in which the exhaust gas recirculation control valve is not closed, the first
The on-off valve is closed.

According to a fourth aspect of the present invention, there is provided a method for driving an exhaust gas recirculation device, wherein a part of an intake passage is formed in a middle of an intake passage extending from an outside air inlet to an intake valve which is opened and closed by an intake valve. Drives a surge tank, an exhaust gas recirculation passage that recirculates part of the exhaust gas in the exhaust gas passage into the intake passage, an exhaust gas recirculation control valve that opens and closes the exhaust gas recirculation passage to adjust the flow rate of the recirculated exhaust gas, and an exhaust gas recirculation control valve. Control valve driving means, and a first intake port and an exhaust port located at a position downstream of the exhaust gas recirculation control valve in the exhaust gas recirculation direction and open from the exhaust gas recirculation passage toward the surge tank and capable of taking in recirculated exhaust gas. A second intake opening from the recirculation passage toward the intake passage between the surge tank and the intake valve opening for taking in recirculation exhaust gas, and opening and closing the first intake and the second intake respectively A first on-off valve and the second on-off valve that,
First drive means and second drive means for driving the first on-off valve and second on-off valve, respectively, and exhaust gas recirculation control by control valve drive means, first drive means, and second drive means according to operating conditions of the engine A driving method for an exhaust gas recirculation device, comprising: a valve, a first opening / closing valve, and a control unit for controlling driving of the second opening / closing valve, wherein the exhaust gas recirculation control valve is opened in an operation region where exhaust gas recirculation is performed. When the first open / close valve and the second open / close valve are opened to shift from an operation region in which exhaust gas recirculation is performed to an operation region in which no exhaust gas recirculation is performed, the first exhaust gas recirculation control valve is closed prior to the valve closing operation of the exhaust gas recirculation control valve. The on-off valve is closed, and the second on-off valve is closed in synchronization with the closing operation of the exhaust gas recirculation control valve.

According to a fifth aspect of the present invention, there is provided a method of driving an exhaust gas recirculation device, wherein a part of an intake passage is formed in a middle of an intake passage extending from an outside air inlet to an intake valve which is opened and closed by an intake valve. Drives a surge tank, an exhaust gas recirculation passage that recirculates part of the exhaust gas in the exhaust gas passage into the intake passage, an exhaust gas recirculation control valve that opens and closes the exhaust gas recirculation passage to adjust the flow rate of the recirculated exhaust gas, and an exhaust gas recirculation control valve. Control valve driving means, and a first intake port and an exhaust port located at a position downstream of the exhaust gas recirculation control valve in the exhaust gas recirculation direction and open from the exhaust gas recirculation passage toward the surge tank and capable of taking in recirculated exhaust gas. A second intake opening from the recirculation passage toward the intake passage between the surge tank and the intake valve opening for taking in recirculation exhaust gas, and opening and closing the first intake and the second intake respectively A first on-off valve and the second on-off valve that,
First drive means and second drive means for driving the first on-off valve and second on-off valve, respectively, and exhaust gas recirculation control by control valve drive means, first drive means, and second drive means according to operating conditions of the engine A driving method for an exhaust gas recirculation device, comprising: a valve, a first opening / closing valve, and a control unit for controlling driving of the second opening / closing valve, wherein the exhaust gas recirculation control valve is opened in an operation region where exhaust gas recirculation is performed. When the first opening / closing valve is opened and the second opening / closing valve is closed to shift from an exhaust gas recirculation operation region to an exhaust gas recirculation operation region, the exhaust gas recirculation control valve is closed. Prior to closing the first on-off valve and opening the second on-off valve, the second on-off valve is closed in synchronization with the closing operation of the exhaust gas recirculation control valve. .

[0016]

According to the exhaust gas recirculation apparatus according to the first aspect of the present invention, the operation shifts from the operation area where the exhaust gas recirculation is performed to the operation area where the exhaust gas recirculation is not performed, or shifts through the operation area where the exhaust gas recirculation is not performed, for example, In the case of acceleration during transition from the stratified combustion region to the homogeneous lean combustion region or through the homogeneous lean region to reach the homogeneous stoichiometric combustion region, the first on-off valve is closed in advance, and the surge tank and intake air are discharged. A state in which the recirculated exhaust gas is taken in from a second intake port provided between the exhaust gas recirculation control valve and the valve port can be brought into a state where the exhaust gas recirculation control valve is closed when switching to the homogeneous lean combustion region.

Therefore, even when the exhaust gas recirculation is performed in the operation region before the combustion switching, the residual amount of the recirculated exhaust gas is reduced by the amount taken into the surge tank and the intake passage from the surge tank to the second intake. Can be reduced. As a result, it is possible to improve the delay of the exhaust gas recirculation stop response, and to stabilize the combustion in the homogeneous lean combustion state.

Further, an operation region in which exhaust gas recirculation is performed, for example,
In the stratified combustion region and the homogeneous stoichiometric combustion region, the first on-off valve can be opened to take in the recirculated exhaust gas into the surge tank.

Thus, in the case of a multi-cylinder engine, the recirculation exhaust gas is uniformly distributed to the respective cylinders, the variation in combustion between the respective cylinders is suppressed, and the fluctuation of torque and the like can be reduced as a whole. It is possible to stabilize combustion, reduce NOx, and the like.

According to the exhaust gas recirculation apparatus according to the second aspect of the present invention, when the operation shifts from the operation area in which the exhaust gas recirculation is performed to the operation area in which the exhaust gas is not recirculated, or shifts past the operation area in which the exhaust gas is not recirculated. In the same manner as in the exhaust gas recirculation device according to claim 1, the first on-off valve is closed and the recirculated exhaust gas is taken in from the second intake port provided in the intake passage downstream of the surge tank. By closing the exhaust gas recirculation control valve and also closing the second on-off valve, an exhaust gas recirculation stop response delay including the recirculated exhaust gas in the exhaust gas recirculation passage from the first intake to the second intake is provided. Therefore, combustion can be further stabilized in a region where exhaust gas recirculation is not performed.

Further, an operation region in which exhaust gas recirculation is performed, for example,
In the stratified combustion region and the homogeneous stoichiometric combustion region, the first on-off valve can be opened and the second on-off valve can be closed, so that the recirculated exhaust gas can be taken in only from the surge tank.

Thus, in the case of a multi-cylinder engine, the recirculation exhaust gas is more uniformly distributed to the respective cylinders, the variation in combustion between the respective cylinders is further suppressed, and the fluctuation of the torque as a whole is reduced. It is possible to further reduce the fuel consumption, to achieve more stable combustion, to reduce NOx, and the like.

According to the driving method of the exhaust gas recirculation device according to the third aspect of the present invention, when the operation is shifted from the operation region where the exhaust gas recirculation is performed to the operation region where the exhaust gas is not recirculated, the closing operation of the exhaust gas recirculation control valve is performed. By closing the first on-off valve in advance, the exhaust gas recirculation can be stopped from a state in which the recirculated exhaust gas is taken in from the second intake port provided in the intake passage downstream of the surge tank in advance.

Therefore, in the operation region where the exhaust gas is not recirculated, the residual amount of the recirculated exhaust gas can be reduced by the amount taken into the surge tank and the intake passage from the surge tank to the second intake. As a result, it is possible to improve an exhaust gas recirculation stop response delay when shifting from the operation region where exhaust gas recirculation is performed to the operation region where exhaust gas recirculation is not performed, and achieve stable combustion in the operation region where exhaust gas recirculation is not performed. be able to.

According to the driving method of the exhaust gas recirculation device according to the fourth aspect of the present invention, in the operating region in which the exhaust gas is recirculated, only the recirculated exhaust gas is taken in from the second intake provided in the intake passage downstream of the surge tank. In addition, since the recirculated exhaust gas is also taken in from the first intake port provided in the surge tank, in the case of a multi-cylinder engine, the recirculated exhaust gas is evenly distributed to each cylinder, and the combustion between the cylinders is reduced. Variations and the like are suppressed. This makes it possible to reduce torque fluctuations and the like as a whole, and to stabilize combustion, reduce NOx, and the like.

When shifting from the operation region in which exhaust gas recirculation is performed to the operation region in which exhaust gas recirculation is not performed, the first on-off valve is closed beforehand, and the recirculated exhaust gas is supplied from the second intake port downstream of the surge tank. Then, by stopping the exhaust gas recirculation, that is, closing the exhaust gas recirculation control valve and closing the second on-off valve simultaneously, the recirculation in the surge tank and the intake passage from the surge tank to the second intake port is performed. It is possible to reduce not only the amount of exhaust gas, but also the residual amount including the amount of recirculated exhaust gas in the exhaust gas recirculation passage from the first intake port to the second intake port, thereby further improving the exhaust gas recirculation stop response delay. Can be. As a result, further stabilization of combustion in a region where exhaust gas recirculation is not performed can be achieved.

According to the driving method of the exhaust gas recirculation device according to the fifth aspect of the present invention, compared with the driving method of the exhaust gas recirculation device according to the fourth aspect, the exhaust gas recirculation device is provided in the surge tank in the operating region where the exhaust gas recirculation is performed. Since the recirculated exhaust gas is taken in only from the first intake port, the recirculated exhaust gas is more uniformly distributed to each cylinder in the case of a multi-cylinder engine, and the variation in combustion among the cylinders is reduced. It is further suppressed. As a result, torque fluctuations and the like as a whole can be further reduced, and further stabilization of combustion and reduction of NOx can be achieved.

[0028]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIGS. 1 and 2 are schematic structural views of an engine employing an embodiment of an exhaust gas recirculation apparatus according to the present invention.
The engine has a cylinder head 20 as shown.
Chamber 23 defined by the lower surface of the cylinder and the concave upper surface 22a of the piston 22 housed in the cylinder block 21
Intake manifold 24 that forms a part of an intake passage that guides outside air to the intake manifold 24, and an intake pipe 24a of the intake manifold 24.
An intake valve 25 that opens and closes an open end of an intake port 20a, that is, an intake valve port 20c, and a rotatably provided upstream position of a surge tank 24b of an intake manifold 24 to achieve a target intake air amount. An electronically controlled throttle valve 26 that opens and closes in response to the pressure, and a high-pressure fuel injection valve 2 that injects fuel directly into the cylinder, that is, into the combustion chamber 23.
8, an exhaust valve 29 disposed on the side opposite to the intake valve 25 with the ignition plug 27 interposed therebetween, for opening and closing the open end of the exhaust port 20b, that is, the exhaust valve port.
And a swirl control valve 35 provided in the intake pipe 24a, a step motor 36 for driving the swirl control valve 35, and the like. The structure is configured. In the engine, the intake port 20 of the cylinder head 20 is used.
a, intake air that guides outside air to the combustion chamber 23 by an intake pipe 24a and a surge tank 24b of the intake manifold 24, an outside air introduction duct (not shown) connected upstream of the surge tank 24b, and having an outside air introduction port for introducing outside air. A passage is formed.

The exhaust manifold 30 is provided with a take-out port 30a for taking out a part of the exhaust gas. An EGR valve 3 as an exhaust gas recirculation control valve fixed to the outer wall of a surge tank 24b of the intake manifold 24 is provided.
4 are connected to the outlet port 30a by the exhaust gas recirculation pipe 31. An outlet passage 34b of the EGR valve 34 is connected to an introduction passage 32 formed integrally with the wall surface of the surge tank 24b and extending in the direction in which the surge tank 24b extends. Two first intake ports 32a are formed which open toward the inside of the tank 24b and take in the recirculated exhaust gas into the surge tank 24b. Further, two branch passages 33 extend from the introduction passage 32 toward the downstream side of the intake pipe 24a, and their ends are open toward the intake pipe 24a, and the intake air downstream of the surge tank 24b. Four second intake ports 33a for taking the recirculated exhaust gas into the passage are formed for each cylinder. The exhaust gas recirculation pipe 31, the introduction passage 32, and the branch passage 33 form an exhaust gas recirculation passage that recirculates a part of the exhaust gas in the exhaust passage into the intake passage.

Further, two first on-off valves 37, which are held by a shaft 37a so as to rotate integrally and open and close the first intake port 32a, are arranged in each area of the first intake port 32a. And these first on-off valves 3
Reference numeral 7 indicates that the opening and closing operation is performed by rotating the shaft 37a by the step motor 38 as the first driving means.

Based on the detection signals of the accelerator opening sensor 40 for detecting the load of the engine and the crank angle sensor 41 for detecting the number of revolutions of the engine, the control unit 39 as a control means executes a predetermined control signal in a stepwise manner. The signals are sent to motors 36 and 38 and an electromagnetic solenoid 45 as a control valve driving means to control respective operations.

The exhaust gas recirculation pipe 31, the introduction passage 32,
Branch passage 33, EGR valve 34, electromagnetic solenoid 4
5, the first intake port 32a, the second intake port 33a, the first on-off valve 37, the step motor 38, the control unit 39, and the like constitute an exhaust gas recirculation device of the present invention.

Next, the operation of the exhaust gas recirculation device will be described. FIG. 3 is a map showing each operation region in the relationship between the engine speed and the load. As shown in FIG. 3, the low-load operation region A is a region in which stratified combustion with an air-fuel ratio of about 40 is performed and exhaust gas recirculation (V ₁ %) is performed, and a medium-load operation region B is homogeneous lean combustion. Is performed, and the exhaust gas recirculation is not performed. The operation region C where the load is higher than B is a region where the homogeneous stoichiometric combustion around the stoichiometric air-fuel ratio is performed and the exhaust gas recirculates (V ₂ %).

[0035] Therefore, the operating region changes along the line L ₁ in FIG. 3, that is, the operation will be described in the case of acceleration, when in region A, as shown in FIG. 4, the EGR valve 34 first The valve is opened to the valve opening (V ₁ %) and the first
The first intake port 32a of the on-off valve 37 in its opened state and is subjected to exhaust gas recirculation and a second inlet 33a, first from the state when it reaches P ₁ point on the line C ₁ in the A region The on-off valve 37 is closed. That is, the first on-off valve 37 is closed before the EGR valve 34 is closed. Thereby, as shown in FIG. 5, the exhaust gas is recirculated only from the second intake port 33a. Subsequently, the EGR valve 34 in a closed state when it reaches the _{P 2} points on the combustion switching line _{C 2.}

[0036] Thus, the recirculated exhaust gas at a position P ₃ points B region completely eliminated, a state where the exhaust gas recirculation is not performed actually.

[0037] By the way, time of up to P ₃ points disappear completely recirculated exhaust gas from the exhaust gas recirculation stopped, the surge tank 2
4b and the second intake 33 from the surge tank 24b.
6 and 7, the amount of recirculated exhaust gas remaining can be reduced by the amount taken in between the intake pipes 24a. Therefore, as shown in FIG. 6 and FIG. Will contribute.

[0038] Then, when the operating region reaches _{P 4} points on different combustion switching line _{C 3} by shifting, with the EGR valve 34 in the open state of the second valve opening _(V 2%) The first on-off valve 37 is opened. When shifting from the region in which the exhaust gas recirculation is not performed, that is, the region B to the region in which the exhaust gas recirculation is performed, that is, the region C, since the recirculated exhaust gas does not remain, the opening timing of the first on-off valve 37 is determined by the EGR valve 34. May be performed simultaneously with or before and after the valve opening operation.

On the other hand, the operating region changes along the line L ₂ in FIG. 3, that is, the operation will be described in the case of deceleration, etc., when in the C region, as shown in FIG. 4, the EGR valve 34 a The valve is opened to the _2- valve opening (V ₂ %) and the first
The first intake port 32a of the on-off valve 37 in its opened state and is subjected to exhaust gas recirculation and a second inlet 33a, first when it reaches P ₅ points on the line C ₄ C-region from the state The on-off valve 37 is closed. Thereby, as shown in FIG. 5, the exhaust gas is recirculated only from the second intake port 33a. Subsequently, the combustion switching line C
The EGR valve 34 in a closed state when it reaches the _{P 6} points on _3. Thus, the recirculated exhaust gas at a position P ₇ point B region completely eliminated, a state where the exhaust gas recirculation is not performed actually. Response delay of the exhaust gas recirculation is stopped at this time, is improved as in the operating region changes along the line L ₁ described above.

[0040] Subsequently, the with operating region is in the open state of the EGR valve first valve opening (V _1%) when it reaches the P ₈ points on different combustion switching line C ₂ by shifting 1 The on-off valve 37 is opened. The opening timing of the first opening / closing valve 37 may be at the same time as or before or after the opening operation of the EGR valve 34 as described above.

According to the above configuration, even when the operating region shifts, even if the operating region before the combustion switching is performing exhaust gas recirculation, the surge tank 24b and the surge tank 24b to the second intake port 33a. The amount of recirculated exhaust gas remaining in the intake pipe 24a can be reduced, and the combustion in the homogeneous lean combustion region B in which exhaust gas recirculation is not performed can be stabilized.

Further, in the stratified combustion region A and the homogeneous stoichiometric combustion region C in which the exhaust gas is recirculated, the recirculated exhaust gas is introduced from a surge tank upstream of the intake pipe 24a branching corresponding to each cylinder, and is regenerated with fresh air. Since the recirculation exhaust gas is sufficiently mixed, the distribution of the recirculation exhaust gas to each cylinder in the case of a multi-cylinder engine is uniformly performed, the variation in combustion between the cylinders is suppressed, and the torque fluctuation is reduced. Stabilization of combustion, reduction of NOx, and the like can be achieved.

FIGS. 8 and 9 are diagrams showing a schematic configuration of an engine employing another embodiment of the exhaust gas recirculation device according to the present invention. The exhaust gas recirculation device according to this embodiment is the same as that shown in FIG.
2 and the embodiment shown in FIG.
And two second on-off valves 42 for opening and closing the
Motor 43 as second driving means for driving the motor 2
Is added.

Here, the two second on-off valves 42 are held by a shaft 42 a so as to rotate integrally. Based on a control signal from the control unit 39, a step motor 43 is driven to rotate the shaft. The opening and closing operation is performed by the rotation of 42a.

Next, the operation of the exhaust gas recirculation system according to the present embodiment when the transition is the operating region along the line L ₁ in the foregoing Figure 3. First, when the exhaust gas recirculation is in the region A, as shown in FIG.
With the valve opening degree (V ₁ %) and the first opening / closing valve 37 and the second opening / closing valve 42 opened, the first intake 32
a and the second intake port 33a performs exhaust gas recirculation. Then, P on the line C ₁ of the A region from the state
_{When one} point is reached, the first on-off valve 37 is closed. Thereby, as shown in FIG. 11, the exhaust gas recirculation is performed only from the second intake port 33a. Then, when it reaches _{P 2} points on the combustion switching line _{C 2,} EGR
The valve 34 is closed, and the second on-off valve 42 is also closed in synchronization with the closing operation of the EGR valve 34.

As a result, the recirculated exhaust gas completely disappears at the point P ₃ ′ earlier than the point P ₃ (in the case of the above embodiment) in the B region where the exhaust gas recirculation is not performed, and the exhaust gas recirculation is actually performed. There is no state.

That is, as compared with the case of the above-described embodiment, the inflow of the recirculated exhaust gas in the introduction passage 32 and the branch passage 33 forming a part of the exhaust gas recirculation passage can be prevented.
As shown in FIG. 2 and FIG. 13, it is possible to further improve the response delay in stopping the recirculation of exhaust gas. This allows
Combustion in the B region can be further stabilized.

[0048] Then, when the operating region reaches _{P 4} points on different combustion switching line _{C 3} by shifting, with the EGR valve 34 in the open state of the second valve opening _(V 2%) The first on-off valve 37 and the second on-off valve 42 are opened.
The opening timing of the first on-off valve 37 and the second on-off valve 42 may be simultaneous with or before or after the opening operation of the EGR valve 34.

According to the above configuration, in the case where the operation region changes, even if the operation region before the combustion switching is performing exhaust gas recirculation, the surge tank 24b and the surge tank 24b to the second intake port 33a. The amount of the recirculated exhaust gas remaining in the introduction passage 32 and the branch passage 33 which forms a part of the exhaust gas recirculation passage can be reduced by the amount taken into the intake pipe 24a, and the homogeneous lean without recirculating the exhaust gas can be reduced. Combustion in the combustion region B can be further stabilized.

In the exhaust gas recirculation system of this embodiment, the EGR valve 34 is opened as shown in FIG. 14 in the operation region where the exhaust gas is recirculated, that is, in the stratified combustion region A and the homogeneous stoichiometric combustion region C. With the first
The on-off valve 37 can also be opened, while the second on-off valve 42 can be closed.

[0051] By way along the operation in this case a line L ₁ in FIG. 3, as described above, when in the A region, EGR
While opening the valve 34 to the first valve opening (V ₁ %),
The first on-off valve 37 while closing the second on-off valve 42 open vital and performing exhaust gas recirculation only the first intake port 32a, P ₁ point on the line C ₁ of the A region from the state Is reached, the first on-off valve 37 is closed, and the second
The on-off valve 42 is opened. Thereby, as shown in FIG. 11, the exhaust gas recirculation is performed only from the second intake port 33a. Subsequently, the combustion switching line C
Upon reaching the P ₂ points on _2, second on-off valve 42 with the EGR valve 34 in the closed state is also in a closed state.

[0052] Further, when the operating region reaches _{P 4} points on different combustion switching line _{C 3} by shifting, first with the EGR valve 34 in the open state of the second valve opening _(V 2%) Only one open / close valve 37 is opened. The opening timing of the first on-off valve 37 may be simultaneous with or before or after the opening operation of the EGR valve 34.

According to the above configuration, in the operating region in which the exhaust gas is recirculated, the first intake port 3 provided in the surge tank 24b is provided.
Since the recirculated exhaust gas is taken in only from the cylinder 2a, the recirculated exhaust gas is distributed more evenly to each cylinder in the case of a multi-cylinder engine, thereby suppressing variations in combustion among the cylinders. As a result, torque fluctuation and the like can be further reduced, and further, combustion can be further stabilized.

In both of the above embodiments, the switching of the combustion is performed by controlling the fuel injection timing, the ignition timing and the like based on information such as the engine speed and the engine load.

FIG. 15 is a sectional view showing the structure of the exhaust gas recirculation passage in the area where the first on-off valve 37 and the second on-off valve 42 are arranged. As shown in FIG. 15, the vicinity of the first intake port 32a and the second intake port 33a of each of the introduction passage 32 and the branch passage 33 forming the exhaust gas recirculation passage is formed such that the center line of the passage is offset. ,
A step 50 is provided on the inner wall of the passage.

Then, as shown in FIG.
When the on-off valve 37 and the second on-off valve 42 are rotated to close the valve, both end regions of the on-off valves 37 and 42 come into close contact with the side surfaces of the step 50.

Thus, in the valve closed state, it is possible to prevent the recirculated exhaust gas from leaking into the surge tank 24b and the intake pipe 24a, and to further improve the stability of combustion in an operating region where exhaust gas recirculation is not performed. be able to.

Also, when the exhaust gas is recirculated by opening only the first on-off valve 37, the leakage of the recirculated exhaust gas from the second on-off valve 42 can be prevented. The distribution of the recirculated exhaust gas is performed more uniformly, which contributes to reduction of torque fluctuation and the like, stabilization of combustion, and the like.

In the embodiment described above, the second intake port 33a for taking in the recirculated exhaust gas is connected to the intake manifold 2
4 is provided so as to open in the middle of the intake pipe 24a. However, the present invention is not limited to this. A passage connected to the branch passage 33 is formed in the cylinder head 20,
A second intake may be provided so as to open from this passage toward the intake port 20a.

In the above embodiment, the butterfly valve is used as the first on-off valve 37 and the second on-off valve 42. However, the present invention is not limited to this. The number of the first on-off valve 37 and the second on-off valve 42 is not limited to two, and may be a number corresponding to the number of the intake pipes 24a. is there. Further, although the homogeneous lean region of the operation region B is set to “no exhaust gas recirculation”, a configuration in which the exhaust gas recirculates slightly may be employed.

Furthermore, in the above-described embodiment, the case where the exhaust gas recirculation system of the present invention is applied to an in-cylinder four-cylinder in-cylinder injection engine has been described. However, the present invention is not limited to this. It is also applicable to an in-line or V-type engine, a horizontally opposed engine, and an engine that injects fuel into an intake pipe.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a direct injection type engine provided with an exhaust gas recirculation device according to the present invention.

FIG. 2 is a diagram showing a schematic configuration of a direct injection type engine provided with an exhaust gas recirculation device according to the present invention.

FIG. 3 is a diagram showing an operation region map of an engine using the exhaust gas recirculation device according to the present invention.

FIG. 4 is a diagram showing an operation state of the exhaust gas recirculation device according to the present invention.

FIG. 5 is a diagram showing an operation state of the exhaust gas recirculation device according to the present invention.

FIG. 6 is a diagram showing a response characteristic of an exhaust gas recirculation stop in the exhaust gas recirculation device according to the present invention.

FIG. 7 is a graph showing exhaust gas recirculation characteristics when combustion is switched using the exhaust gas recirculation device according to the present invention.

FIG. 8 is a view showing a schematic configuration of a direct injection type engine provided with another embodiment of the exhaust gas recirculation device according to the present invention.

FIG. 9 is a view showing a schematic configuration of a direct injection type engine provided with another embodiment of the exhaust gas recirculation device according to the present invention.

FIG. 10 is a view showing an operation state of the exhaust gas recirculation device shown in FIGS. 8 and 9;

FIG. 11 is a view showing an operation state of the exhaust gas recirculation device shown in FIGS. 8 and 9;

12 is a diagram showing response characteristics of the exhaust gas recirculation device shown in FIGS. 8 and 9 when the exhaust gas recirculation is stopped.

FIG. 13 is a diagram showing exhaust gas recirculation characteristics when switching of combustion is performed using the exhaust gas recirculation devices shown in FIGS. 8 and 9;

FIG. 14 is a view showing another operation state of the exhaust gas recirculation device shown in FIGS. 8 and 9;

FIG. 15 is a cross-sectional view showing a configuration of a passage in a region where a first on-off valve and a second on-off valve constituting a part of the exhaust gas recirculation device are arranged, FIG. b) shows a state where both on-off valves are closed.

FIG. 16 is a schematic configuration diagram of a direct injection type engine provided with a conventional exhaust gas recirculation device.

FIG. 17 is a diagram showing an operation region map in the relationship between the engine speed and the load.

FIG. 18 is a diagram showing a response characteristic of an exhaust gas recirculation stop in a conventional exhaust gas recirculation device.

FIG. 19 is a diagram showing exhaust gas recirculation characteristics when switching of combustion is performed using a conventional exhaust gas recirculation device.

[Explanation of symbols]

 Reference Signs List 20 cylinder head 20a intake port 20b exhaust port 20c intake valve port 21 cylinder block 22 piston 23 combustion chamber 24 intake manifold 24a intake pipe (intake passage) 24b surge tank 25 intake valve 26 throttle valve 27 ignition plug 28 high-pressure fuel injection valve 29 exhaust Valve 30 Exhaust manifold (exhaust passage) 31 Exhaust recirculation pipe (exhaust recirculation passage) 32 Introductory passage (exhaust recirculation passage) 32a First intake port 33 Branch passage (exhaust recirculation passage) 33a Second intake port 34 EGR valve (exhaust recirculation control) Valve) 35 Swirl control valve 36 Step motor 37 First open / close valve 37a Shaft 38 Step motor (First drive means) 39 Control unit (Control means) 40 Accelerator opening sensor 41 Clamp Angular sensor 42 second on-off valve 42a shaft 43 step motor (second driving means) 45 electromagnetic solenoid (regulating valve drive means)

Claims (5)

[Claims] 1. A surge tank which is located in the middle of an intake passage extending from an outside air inlet to an intake valve which is opened and closed by an intake valve and forms a part of an intake passage, and a part of exhaust gas in an exhaust passage is sucked. An exhaust gas recirculation passage that recirculates into the passage;
An exhaust gas recirculation device comprising: an exhaust gas recirculation control valve that opens and closes an exhaust gas recirculation passage to adjust a flow rate of recirculated exhaust gas; and a control valve driving unit that drives the exhaust gas recirculation control valve, wherein the exhaust gas recirculation control valve is provided. A first intake port located at a position downstream of the exhaust gas recirculation direction from the exhaust gas recirculation direction and opening toward the surge tank from the exhaust gas recirculation passage and capable of taking in recirculated exhaust gas; A second intake port that opens toward the intake passage between the first intake port and the second intake port, and that opens and closes the first intake port; a first drive unit that drives the first open / close valve; The control valve driving means and the first
Control means for controlling driving of the exhaust gas recirculation control valve and the first on-off valve by driving means. 2. A surge tank which is located in the middle of an intake passage extending from an outside air inlet to an intake valve which is opened and closed by an intake valve and forms a part of the intake passage, and a part of exhaust gas in the exhaust passage is sucked. An exhaust gas recirculation passage that recirculates into the passage;
An exhaust gas recirculation device comprising: an exhaust gas recirculation control valve that opens and closes an exhaust gas recirculation passage to adjust a flow rate of recirculated exhaust gas; and a control valve driving unit that drives the exhaust gas recirculation control valve, wherein the exhaust gas recirculation control valve is provided. A first intake port located at a position downstream of the exhaust gas recirculation direction from the exhaust gas recirculation direction and opening toward the surge tank from the exhaust gas recirculation passage and capable of taking in recirculated exhaust gas; A second intake port that opens toward the intake passage between the first intake port and the second intake port to open and close the first intake port and the second intake port; A first driving valve and a second driving valve, respectively.
A drive unit and a second drive unit, and the exhaust gas recirculation control valve by the control valve drive unit, the first drive unit, and the second drive unit in accordance with operating conditions of the engine;
An exhaust gas recirculation device comprising: a first opening / closing valve; and control means for controlling driving of the second opening / closing valve. 3. A surge tank which is located in the middle of an intake passage extending from an outside air inlet to an intake valve which is opened and closed by an intake valve and forms a part of an intake passage, and a part of exhaust gas in an exhaust passage is taken in by a suction tank. An exhaust gas recirculation passage that recirculates into the passage;
An exhaust gas recirculation control valve for opening and closing the exhaust gas recirculation passage to adjust the flow rate of recirculated exhaust gas; a control valve driving means for driving the exhaust gas recirculation control valve; and a position downstream of the position where the exhaust gas recirculation control valve is provided in the exhaust gas recirculation direction. And a first intake opening from the exhaust gas recirculation passage toward the surge tank and capable of taking in recirculated exhaust gas, and an opening from the exhaust gas recirculation passage to the intake passage between the surge tank and the intake valve port to take in recirculated exhaust gas. A second intake port to be obtained, a first on-off valve for opening and closing the first intake port, a first drive means for driving the first on-off valve, and a control valve drive means and a first drive means according to operating conditions of the engine. A driving method of an exhaust gas recirculation device comprising: an exhaust gas recirculation control valve; and control means for controlling driving of a first opening / closing valve. Opening the first on-off valve and closing the first on-off valve prior to the closing operation of the exhaust gas recirculation control valve when shifting from the operation region for performing exhaust gas recirculation to the operation region for not performing exhaust gas recirculation. And a method of driving the exhaust gas recirculation device. 4. A surge tank which is located in the middle of an intake passage extending from an outside air inlet to an intake valve opened and closed by an intake valve and forms a part of an intake passage, and a part of exhaust gas in an exhaust passage is taken in by a suction tank. An exhaust gas recirculation passage that recirculates into the passage;
An exhaust gas recirculation control valve for opening and closing the exhaust gas recirculation passage to adjust the flow rate of recirculated exhaust gas; a control valve driving means for driving the exhaust gas recirculation control valve; and a position downstream of the position where the exhaust gas recirculation control valve is provided in the exhaust gas recirculation direction. And a first intake opening from the exhaust gas recirculation passage toward the surge tank and capable of taking in recirculated exhaust gas, and an opening from the exhaust gas recirculation passage to the intake passage between the surge tank and the intake valve port to take in recirculated exhaust gas. A second intake, a first on-off valve and a second on-off valve for opening and closing the first and second intakes, respectively, and a first on-off valve and a second on-off valve for driving the second on-off valve, respectively.
The driving means, the second driving means, and the control valve driving means, the first driving means, and the second driving means for driving the exhaust gas recirculation control valve, the first on-off valve, and the second on-off valve according to the operating conditions of the engine. A control method for controlling the exhaust gas recirculation device, comprising: in an operation region for performing exhaust gas recirculation, opening the exhaust gas recirculation control valve and opening the first on-off valve and the second on-off valve; When shifting from the operation region in which the exhaust gas recirculation is performed to the operation region in which the exhaust gas recirculation is not performed, the first on-off valve is closed prior to the closing operation of the exhaust gas recirculation control valve, and the exhaust gas recirculation control valve is closed. A method for driving an exhaust gas recirculation device, wherein the second on-off valve is closed in synchronization with an operation. 5. A surge tank which is located in the middle of an intake passage extending from an outside air inlet to an intake valve which is opened and closed by an intake valve to form a part of the intake passage, and a part of exhaust gas in the exhaust passage is taken in. An exhaust gas recirculation passage that recirculates into the passage;
An exhaust gas recirculation control valve for opening and closing the exhaust gas recirculation passage to adjust the flow rate of recirculated exhaust gas; a control valve driving means for driving the exhaust gas recirculation control valve; and a position downstream of the position where the exhaust gas recirculation control valve is provided in the exhaust gas recirculation direction. And a first intake opening from the exhaust gas recirculation passage toward the surge tank and capable of taking in recirculated exhaust gas, and an opening from the exhaust gas recirculation passage to the intake passage between the surge tank and the intake valve port to take in recirculated exhaust gas. A second intake, a first on-off valve and a second on-off valve for opening and closing the first and second intakes, respectively, and a first on-off valve and a second on-off valve for driving the second on-off valve, respectively.
The driving means, the second driving means, and the control valve driving means, the first driving means, and the second driving means for driving the exhaust gas recirculation control valve, the first on-off valve, and the second on-off valve according to the operating conditions of the engine. A control method for controlling an exhaust gas recirculation device, comprising: a control means for controlling the exhaust gas recirculation device, wherein in an operation region for recirculating exhaust gas, the exhaust gas recirculation control valve is opened, the first open / close valve is opened, and the second open / close valve is opened. Closing the first open / close valve and closing the second open / close valve prior to the closing operation of the exhaust gas recirculation control valve when shifting from the operation region where the exhaust gas recirculation is performed to the operation region where the exhaust gas recirculation is not performed. A method for driving an exhaust gas recirculation device, comprising: opening an on-off valve and closing the second on-off valve in synchronization with a closing operation of the exhaust gas recirculation control valve.