JP2012132337A - Control device of internal combustion engine with supercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine with a supercharger, the control device capable of achieving preferable responsiveness, fuel consumption and warming-up property of a turbocharger.SOLUTION: The control device includes: a first exhaust passage to allow exhaust gas of a first cylinder group in an internal combustion engine having a plurality of cylinders, to flow into one inlet of a turbine; a second exhaust passage to allow exhaust gas of a second cylinder group in the internal combustion engine to flow into the other inlet of the turbine, in which exhaust gas at a temperature higher than that of the exhaust gas flowing in the first exhaust passage; an external EGR passage connecting the first exhaust passage and the second exhaust passage to an air intake passage of the internal combustion engine; and a changeover valve that can selectively switch between a first communication state of communicating the first exhaust passage and the external EGR passage and a second communication state communicating the second exhaust passage and the external EGR passage. During a warming-up operation, the control device keeps the second communication state and switches into the first communication state after the warming-up operation.

Description

  The present invention relates to a control device for an internal combustion engine with a supercharger.

  Conventionally, as disclosed in, for example, Patent Document 1, an internal combustion engine including a twin entry turbocharger is known. An internal combustion engine provided with a twin entry turbocharger disclosed in Patent Document 1 includes a first exhaust passage that guides first exhaust from a first cylinder group to a turbine among a plurality of cylinders. In addition, a second exhaust passage for guiding the second exhaust from the second cylinder group to the turbine among the plurality of cylinders is provided. Furthermore, an external EGR passage that recirculates a part of the first exhaust gas as EGR gas to the intake system is provided.

JP 2009-287434 A

  In the internal combustion engine provided with the conventional twin entry turbocharger, it is required to increase the pulsation by setting the second exhaust to a high temperature from the viewpoint of the response of the turbocharger. Further, when a part of the first exhaust gas is recirculated to the intake system as EGR gas, the first exhaust gas is required to have a low temperature from the viewpoint of fuel efficiency. On the other hand, from the viewpoint of warm-up performance, the temperature of the first exhaust is required to be high. Since both requirements are opposite, it is difficult to satisfy these requirements in the conventional internal combustion engine.

  The present invention has been made to solve the above-described problems, and in an internal combustion engine equipped with a twin-entry turbocharger, a turbocharger that can achieve both responsiveness, fuel consumption, and warm-up performance of the turbocharger. It is an object of the present invention to provide a control device for a built-in internal combustion engine.

In order to achieve the above object, a first invention is a control device for an internal combustion engine with a supercharger,
A turbocharger with a turbine having two inlets;
A first exhaust passage through which exhaust gas of a first cylinder group of an internal combustion engine having a plurality of cylinders flows into one inlet of the turbine;
The second exhaust passage through which the exhaust gas of the second cylinder group of the internal combustion engine flows into the other inlet of the turbine and the exhaust gas having a temperature higher than the exhaust gas flowing through the first exhaust passage flows. When,
An external EGR passage that connects the first exhaust passage and the second exhaust passage to the intake passage of the internal combustion engine and recirculates a part of the exhaust gas to the intake passage;
Switching capable of selectively switching between a first communication state in which the first exhaust passage and the external EGR passage are communicated and a second communication state in which the second exhaust passage and the external EGR passage are in communication A valve,
Warm-up determination means for determining whether the internal combustion engine is warming up;
When it is determined that the internal combustion engine is warming up, the switching valve sets the second communication state. When it is determined that the internal combustion engine is not warming up, the switching valve sets the first communication state. And a communication state switching means for making a state.

The second invention is the first invention, wherein
First cooling means for cooling the first exhaust passage;
And a second cooling means for cooling the second exhaust passage at a temperature higher than that of the first cooling means.

The third invention is the first or second invention, wherein
A surface area of the second exhaust passage is smaller than a surface area of the first exhaust passage.

  According to the first invention, the second exhaust passage and the external EGR passage can be in communication with each other during warm-up. Therefore, warm-up can be promoted. In addition, after the warm-up, the first exhaust passage and the external EGR passage can be in communication with each other. Therefore, it is possible to improve the response and fuel consumption of the turbocharger. For this reason, according to this invention, the response of a turbocharger, fuel consumption, and warm-up property can be made compatible.

  According to the second invention, the second exhaust passage is cooled at a temperature higher than that of the first cooling means, so that the exhaust gas flowing through the second exhaust passage is converted into the first exhaust passage. Higher than the exhaust gas flowing through the.

  According to the third aspect, since the surface area of the second exhaust passage is smaller than the surface area of the first exhaust passage, the exhaust gas flowing through the second exhaust passage is made more than the exhaust gas flowing through the first exhaust passage. Can be hot.

It is a figure for demonstrating the system configuration | structure of embodiment of this invention. 4 is a flowchart of a control routine executed by the ECU 50 in the embodiment of the present invention. It is a figure which shows the shape of the exhaust port 16 formed in a cylinder head.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted.

Embodiment 1 FIG.
[System Configuration of Embodiment 1]
FIG. 1 is a diagram for explaining a system configuration according to the first embodiment of the present invention. The system shown in FIG. 1 includes an internal combustion engine 10. The internal combustion engine 10 is a four-cycle engine mounted on a vehicle or the like and used as a power source. Although the internal combustion engine 10 shown in FIG. 1 is an in-line four-cylinder type, in the present invention, the number of cylinders and the cylinder arrangement are not limited thereto.

  An intake passage 12 and an exhaust passage 14 are connected to each cylinder of the internal combustion engine 10. In the present description, the exhaust passage 14 is a concept including an exhaust port 16 of each cylinder formed in the cylinder head of the internal combustion engine 10, a first exhaust manifold 18, and a second exhaust manifold 20. The first exhaust manifold 18 is connected to the exhaust ports 16 of the first cylinder (# 1) and the fourth cylinder (# 4). The second exhaust manifold 20 is connected to the exhaust ports 16 of the second cylinder (# 2) and the third cylinder (# 3). In the following description, the first cylinder (# 1) and the fourth cylinder (# 4) are referred to as a first cylinder group, and the second cylinder (# 2) and the third cylinder (# 3) are referred to as a second cylinder group.

  The internal combustion engine 10 also includes a turbocharger 24 that performs supercharging with the energy of the exhaust gas. The turbocharger 24 includes a turbine 24a that is rotated by the energy of the exhaust gas, and a compressor 24b that is rotated by being driven by the turbine 24a. The turbine 24 a is arranged in the middle of the exhaust passage 14, and the compressor 24 b is arranged in the middle of the intake passage 12. A catalyst 26 for purifying harmful components in the exhaust gas is provided in the exhaust passage 14 downstream of the turbine 24a. As the catalyst 26, for example, a three-way catalyst is used.

  The turbine 24 a includes two exhaust gas inlets 28 and 30. The downstream part of the first exhaust manifold 18 joins and is connected to the introduction port 28. The downstream part of the second exhaust manifold 20 joins and is connected to the inlet 30. In this way, a twin entry turbocharger is configured.

  An air cleaner (not shown) is provided near the inlet of the intake passage 12. An air flow meter 32 for detecting the intake air amount is provided in the vicinity of the downstream side of the air cleaner. A compressor 24 b is provided downstream of the air flow meter 32. A water-cooled intercooler (not shown) is provided downstream of the compressor 24b. The fresh air drawn through the air cleaner is compressed by the compressor 24b of the turbocharger 24 and then cooled by the intercooler.

  An electronically controlled throttle valve 34 is provided downstream of the intercooler. The fresh air that has passed through the throttle valve 34 flows into an intake manifold 36 formed in the downstream portion of the intake passage 12. The fresh air that has flowed into the intake manifold 36 is distributed and flows into each cylinder. The intake manifold 36 is provided with an intake pipe pressure sensor 38 for detecting the internal pressure.

  Further, the system of the present embodiment includes an external EGR passage 40 for returning a part of the exhaust gas to the intake passage 12. The downstream end of the external EGR passage 40 is connected to the intake manifold 36. In the middle of the external EGR passage 40, an electronically controlled EGR valve 42, a water-cooled EGR cooler 44, and an EGR catalyst (not shown) are provided. The upstream end of the external EGR passage 40 is connected to the first exhaust manifold 18 and the second exhaust manifold 20, respectively.

  Near the upstream end of the external EGR passage 40, a first communication state in which the first exhaust manifold 18 communicates with the external EGR passage 40, and a second communication state in which the second exhaust manifold 20 communicates with the external EGR passage 40, An electronically controlled switching valve 46 is provided for selective switching.

  The system of this embodiment further includes an ECU (Electronic Control Unit) 50. In addition to the air flow meter 32 and the intake pipe pressure sensor 38 described above, an internal combustion engine such as a crank angle sensor 52 for detecting the crank angle and a water temperature sensor 54 for detecting the coolant temperature of the engine cooling water are input to the ECU 50. Various sensors for detecting 10 operating states are connected.

  In addition to the throttle valve 34, EGR valve 42, and switching valve 46 described above, the ECU 50 includes an injector for supplying fuel into the cylinder, and an ignition plug for igniting the fuel supplied into the cylinder. Various actuators for controlling the operating state of the internal combustion engine 10 are connected. The ECU 50 controls the operating state of the internal combustion engine 10 by operating various actuators according to a predetermined program based on the outputs of the various sensors described above.

  Next, an exhaust cooling system in the system of this embodiment will be described. The system of this embodiment includes two different exhaust cooling systems for the first cylinder group (# 1, # 4) and the second cylinder group (# 2, # 3). A cooling water passage is formed around the exhaust port 16 of the first cylinder group (for example, a cylinder head) through which cooling water of a water-cooled intercooler flows. On the other hand, the exhaust port 16 of the second cylinder group is formed with a cooling water passage through which engine cooling water flows in the periphery (for example, cylinder head).

  The cooling water of the intercooler is cooler than the engine cooling water, the exhaust gas flowing through the exhaust port 16 of the first cylinder group is cooled at a low water temperature, and the exhaust gas flowing through the exhaust port 16 of the second cylinder group is higher. Cooled at water temperature. Therefore, the exhaust gas flowing through the first exhaust manifold 18 has a lower temperature than the exhaust gas flowing through the second exhaust manifold 20. In the system of the present embodiment in which a part of the exhaust gas is recirculated to the intake passage 12 via the external EGR passage 40, it is desirable to pass a large amount of heat to the EGR cooler 44 during warm-up to promote warm-up. . On the other hand, after warming up, it is desirable to introduce as low a temperature EGR gas as possible from the viewpoint of improving fuel efficiency because the intake air temperature can be lowered.

[Control in Embodiment 1]
Therefore, in the system of the present embodiment, the second exhaust manifold 20 having a high exhaust temperature is communicated with the external EGR passage 40 gas during warm-up, and the first exhaust manifold 18 and the external EGR passage having a low exhaust temperature after warm-up are communicated. 40 to communicate.

(Control routine)
FIG. 2 is a flowchart of a control routine executed by the ECU 50 in order to realize the above-described operation. This control routine is executed every predetermined time from the engine start to the completion of warm-up.

  In the routine shown in FIG. 2, first, in step S100, the ECU 50 determines whether or not the operation region is an EGR introduction region. Specifically, the ECU 50 stores in advance a relationship map that defines the relationship between the engine speed, the load, and the opening degree of the EGR valve 42. The ECU 50 acquires the opening degree of the EGR valve 42 corresponding to the engine speed and the load from this relationship map. When the opening degree of the EGR valve 42 is larger than 0, it is determined that the region is the EGR introduction region. The engine speed is calculated from the value detected by the crank angle sensor 52. The load is calculated based on, for example, the intake air amount detected by the air flow meter 32 and the intake pipe internal pressure detected by the intake pipe pressure sensor 38.

  If it is determined in step S100 that the operation region is not the EGR introduction region, then the processing of this routine is terminated. On the other hand, when it is determined in step S100 that the operation region is the EGR introduction region, the ECU 50 next determines whether or not the vehicle is warming up (step S110). After the engine is started, it is determined that the engine cooling water is warming up when the temperature of the engine cooling water is not more than an appropriate temperature (for example, about 80 ° C.). The water temperature of the engine cooling water is detected by a water temperature sensor 54.

  If it is determined in step S110 that the engine is warming up, the ECU 50 executes EGR gas extraction from the second cylinder group (# 2, # 3) (step S120). Specifically, the ECU 50 sends a switching control signal to the switching valve 46 to bring the second exhaust manifold 20 and the external EGR passage 40 into communication and to make the first exhaust manifold 18 and the external EGR passage 40 out of communication. Output. Thereafter, the processing of this routine is terminated.

  On the other hand, if it is determined in step S110 that the engine is not warming up, that is, if it is determined that the engine has been warmed up, the ECU 50 extracts the EGR gas from the first cylinder group (# 1, # 4). Is executed (step S130). Specifically, the ECU 50 sends a switching control signal to the switching valve 46 to bring the first exhaust manifold 18 and the external EGR passage 40 into communication and to make the second exhaust manifold 20 and external EGR passage 40 out of communication. Output. Thereafter, the processing of this routine is terminated.

  As described above, according to the routine shown in FIG. 2, the second exhaust manifold 20 and the external EGR passage 40 can be in communication with each other during warm-up. Therefore, warm-up can be promoted. Further, according to the routine shown in FIG. 2, the first exhaust manifold 18 and the external EGR passage 40 can be brought into communication with each other after warm-up. Therefore, it is possible to improve the response and fuel consumption of the turbocharger. For this reason, according to the system of the present embodiment, it is possible to realize both of the responsiveness of the turbocharger, improvement in fuel consumption, and promotion of warm-up.

  By the way, in the system of the first embodiment described above, the exhaust port 16 of the first cylinder group is cooled by the cooling water of the intercooler, and the exhaust port 16 of the second cylinder group is cooled by the engine cooling water. 2 The exhaust gas flowing through the exhaust manifold 20 is set to a higher temperature than the exhaust gas flowing through the first exhaust manifold 18. However, the configuration for this is not limited to this. For example, the exhaust port 16 may have a shape as shown in FIG. FIG. 3 is a view showing the shape of the exhaust port 16 formed in the cylinder head. The exhaust ports of the first cylinder group (# 1, # 4) shown in FIG. 3 are independent of each other. On the other hand, the exhaust ports 16 of the second cylinder group (# 2, # 3) are merged inside the cylinder head. By combining the exhaust port 16 inside the cylinder head, the surface area of the exhaust port 16 is reduced. Therefore, the exhaust port 16 of the second cylinder group has a smaller surface area than the exhaust port 16 of the first exhaust group, and the cooling amount to the flowing exhaust gas is also small. As a result, the exhaust gas flowing through the second exhaust manifold 20 can be at a higher temperature than the exhaust gas flowing through the first exhaust manifold 18.

  Further, in the system of the first embodiment described above, the exhaust gas is cooled by cooling the exhaust port 16, but the configuration for cooling the exhaust gas is limited to this. is not. For example, the first exhaust manifold 18 may be cooled with intercooler cooling water, and the second exhaust manifold 20 may be cooled with engine cooling water.

  In the system of the first embodiment described above, the EGR cooler 44 and the intercooler may be a cooling system sharing a water channel.

  In the first embodiment described above, the turbocharger 24 is the “turbocharger” in the first invention, the turbine 24a is the “turbine” in the first invention, and the first exhaust manifold 18 is the first turbocharger. In the first invention, the second exhaust manifold 20 is connected to the “second exhaust passage” in the first invention, and the intake manifold 36 is connected to the “intake passage” in the first invention. The EGR passage 40 corresponds to the “external EGR passage” in the first invention, and the switching valve 46 corresponds to the “switching valve” in the first invention.

  Also, here, the ECU 50 executes the process of step S110 so that the “warm-up determination means” in the first invention executes the processes of step S120 and step S130. The “communication state switching means” in FIG.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Intake passage 14 Exhaust passage 16 Exhaust port 18 1st exhaust manifold 20 2nd exhaust manifold 24 Turbocharger 24a Turbine 24b Compressor 26 Catalyst 28, 30 Inlet 32 Air flow meter 34 Throttle valve 36 Intake manifold 38 Intake pipe pressure sensor 40 External EGR passage 42 EGR valve 44 EGR cooler 46 Switching valve 50 ECU (Electronic Control Unit)
52 Crank angle sensor 54 Water temperature sensor

Claims (3)

A turbocharger with a turbine having two inlets;
A first exhaust passage through which exhaust gas of a first cylinder group of an internal combustion engine having a plurality of cylinders flows into one inlet of the turbine;
The second exhaust passage through which the exhaust gas of the second cylinder group of the internal combustion engine flows into the other inlet of the turbine and the exhaust gas having a temperature higher than the exhaust gas flowing through the first exhaust passage flows. When,
An external EGR passage that connects the first exhaust passage and the second exhaust passage to the intake passage of the internal combustion engine and recirculates a part of the exhaust gas to the intake passage;
Switching capable of selectively switching between a first communication state in which the first exhaust passage and the external EGR passage are communicated and a second communication state in which the second exhaust passage and the external EGR passage are in communication A valve,
Warm-up determination means for determining whether the internal combustion engine is warming up;
When it is determined that the internal combustion engine is warming up, the switching valve sets the second communication state. When it is determined that the internal combustion engine is not warming up, the switching valve sets the first communication state. Communication state switching means to be in a state;
A control device for an internal combustion engine with a supercharger. First cooling means for cooling the first exhaust passage;
Second cooling means for cooling the second exhaust passage at a higher temperature than the first cooling means;
The control apparatus for an internal combustion engine with a supercharger according to claim 1.   3. The control apparatus for an internal combustion engine with a supercharger according to claim 1, wherein a surface area of the second exhaust passage is smaller than a surface area of the first exhaust passage.

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