JP2018184870A - Control device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a response delay of control for adjusting an amount of introduction of exhaust gas recirculation gas into intake air by an exhaust gas recirculation device. SOLUTION: An intake passage 4 and an exhaust passage 14 leading to a combustion chamber 2, a supercharger 10 provided with a compressor arranged in the intake passage and a turbine arranged in the exhaust passage, and a downstream side of a compressor 11 in the intake passage 4. Exhaust gas having a first exhaust gas recirculation passage 21 and an exhaust gas recirculation valve 22 that connect the throttle valve 5 arranged on the side of the exhaust passage 14 to the downstream side of the turbine 12 in the exhaust passage 14 and the upstream side of the compressor 11 in the intake passage 4. A second exhaust gas recirculation passage that connects the recirculation device 20 to the downstream side of the turbine 12 of the exhaust passage 14 or the upstream side of the exhaust gas recirculation valve 22 of the first exhaust gas recirculation passage 21 and the downstream side of the throttle valve 5 of the intake air passage 4. 31 and the control device E of the engine including the second exhaust gas recirculation device 30 including the exhaust gas recirculation gas supercharger 33 that supercharges the exhaust gas in the second exhaust gas recirculation passage 31 and introduces it into the intake air. [Selection diagram] Figure 1

Description

The present invention relates to an engine control device including an exhaust gas recirculation device that recirculates a part of exhaust gas to intake air.

Engines equipped with an exhaust gas recirculation device that recirculates a part of exhaust gas to intake air are widely used. The exhaust gas recirculation device uses a part of the exhaust gas discharged from the combustion chamber as the exhaust gas recirculation gas via the exhaust gas recirculation passage that connects the exhaust passage drawn from the combustion chamber and the intake passage leading to the combustion chamber. It is returning to the passage.

By introducing the exhaust gas recirculation gas into the intake air, the oxygen concentration in the intake air decreases. Combustion in a state where the oxygen concentration is low lowers the combustion temperature in the combustion chamber, and as a result, generation of nitrogen oxides (NO _x ) can be suppressed. Moreover, since the intake pipe negative pressure can be reduced by introducing the exhaust gas recirculation gas, the effect of improving the fuel consumption can be expected by reducing the throttle loss.

  For example, in Patent Document 1, as a turbocharger, a turbocharger turbine is provided in an exhaust passage, a turbocharger compressor is provided in an intake passage, and the upstream side of the turbine under a relatively high pressure in the exhaust passage (for example, exhaust A technique of a high-pressure exhaust gas recirculation device that introduces exhaust gas recirculation gas from the vicinity of the manifold) to the downstream side of the compressor in the intake passage (for example, near the intake manifold) is disclosed.

  Further, for example, Patent Document 2 discloses a technique of a low-pressure exhaust gas recirculation device that introduces exhaust recirculation gas from a downstream side of a turbine having a relatively low pressure in an exhaust passage to an upstream side of a compressor in an intake passage. It is disclosed.

JP 2004-100508 A JP 2010-236381 A

  In a turbocharged engine equipped with a turbocharger, in some operating regions, the intake pressure near the intake manifold may be higher than the exhaust pressure near the exhaust manifold. Thus, when the intake side pressure is higher than the exhaust side pressure, there is a problem that it is difficult to introduce the exhaust gas recirculation gas by the high pressure exhaust gas recirculation device in the operation region.

  On the other hand, if the low-pressure exhaust gas recirculation device is used, the exhaust gas recirculation gas is recirculated from the downstream side of the turbine in the exhaust passage to the upstream side of the compressor in the intake passage, so that the high-pressure exhaust gas recirculation device cannot be used. Even in the region, it may be possible to introduce the exhaust gas recirculation gas by the low-pressure exhaust gas recirculation device.

  However, even when a low-pressure exhaust gas recirculation device is used, the amount of exhaust gas recirculation gas that can be introduced into intake air is limited if the differential pressure between the intake air pressure and the exhaust gas pressure is small. Further, when the low-pressure exhaust gas recirculation device is used, since the inlet of the exhaust gas recirculation gas to the intake passage is far from the combustion chamber, a response delay (time lag) is easily caused when the amount of exhaust gas recirculation gas is increased or decreased.

  For example, in a low-pressure exhaust gas recirculation system, during transient operation that shifts from deceleration to acceleration, a response delay occurs in the control that increases the amount of exhaust recirculation gas introduced, and knocking occurs along with deterioration of combustion due to shortage of exhaust recirculation gas It may cause. Further, during a transient operation that shifts from acceleration to deceleration, there is a response delay in the control for reducing the amount of exhaust gas recirculation gas introduced, which may cause misfire due to excessive exhaust gas recirculation gas.

  Accordingly, an object of the present invention is to suppress a response delay in control for adjusting the amount of exhaust gas recirculation gas introduced into intake air by the exhaust gas recirculation device.

  In order to solve the above problems, the present invention provides an intake passage and an exhaust passage that communicate with a combustion chamber, a compressor that is disposed in the intake passage and supercharges intake air to the combustion chamber, and an exhaust gas that is disposed in the exhaust passage. A turbocharger including a turbine that rotates and transmits rotation to the compressor, a throttle valve disposed downstream of the compressor in the intake passage, a downstream side of the turbine in the exhaust passage, and the intake passage A first exhaust gas recirculation device that includes a first exhaust gas recirculation passage that connects the upstream side of the compressor and an exhaust gas recirculation valve that opens and closes the first exhaust gas recirculation passage, and introduces part of the exhaust gas into the intake air, The downstream side of the turbine in the exhaust passage or the upstream side of the exhaust recirculation valve in the first exhaust recirculation passage is connected to the downstream side of the throttle valve in the intake passage. A second exhaust gas recirculation provided with a second exhaust gas recirculation passage and an exhaust gas recirculation supercharger which is disposed in the second exhaust gas recirculation passage and supercharges the exhaust gas in the second exhaust gas recirculation passage and introduces it into the intake air The engine control device equipped with the device was adopted.

  Here, it is possible to employ a configuration in which an exhaust recirculation gas boost valve is provided downstream of the exhaust recirculation gas supercharger in the second exhaust recirculation passage.

  An exhaust gas return passage connecting the exhaust gas recirculation gas supercharger in the second exhaust gas recirculation passage and the boost valve for exhaust gas recirculation gas and a downstream side of the turbine in the exhaust passage; and the exhaust gas return passage A configuration including an exhaust gas recirculation gas blow-off valve disposed at the position can be employed.

  A first pressure sensor disposed between the exhaust recirculation gas supercharger in the second exhaust recirculation passage and the exhaust recirculation gas boost valve; and an exhaust recirculation gas boost valve in the second exhaust recirculation passage. A second pressure sensor disposed on the downstream side or on the downstream side of the throttle valve in the intake passage, and the exhaust gas recirculation gas boost valve includes information on pressure acquired by the first pressure sensor and the second pressure. It is possible to adopt a configuration in which opening and closing is controlled based on pressure information acquired by a sensor.

  In each of these aspects, an exhaust recirculation gas cooler is provided in the middle of the first exhaust recirculation passage, and the second exhaust recirculation passage is connected to a downstream side of the exhaust recirculation gas cooler of the first exhaust recirculation passage. be able to.

  In each of these aspects, the second exhaust recirculation passage is connected to the downstream side of the connection portion of the exhaust passage with the first exhaust recirculation passage, and an exhaust recirculation gas cooler is provided in the middle of the second exhaust recirculation passage. Can be adopted.

  In each of these aspects, a residual gas discharge passage connecting the intake passage downstream of the compressor and upstream of the throttle valve and the exhaust passage downstream of the turbine, and a residual gas opening and closing of the residual gas discharge passage. A configuration including a gas exhaust valve and a residual gas exhaust device that exhausts a part of the residual gas in the intake passage to the exhaust passage may be employed.

  The present invention relates to a first exhaust gas recirculation device that connects a downstream side of a turbine in an exhaust passage and an upstream side of a compressor in an intake passage and introduces a part of the exhaust gas into the intake air; A second exhaust gas recirculation device that connects the upstream side of the exhaust gas recirculation valve of the first exhaust gas recirculation passage and the downstream side of the throttle valve of the intake air passage to supercharge exhaust gas by an exhaust recirculation gas supercharger and introduce it into the intake air Therefore, it is possible to suppress a response delay in the control for adjusting the introduction amount of the exhaust gas recirculation gas.

1 is a schematic diagram of an engine control device showing an embodiment of the present invention. FIG. It is a schematic diagram of the control apparatus of the engine which shows other embodiment. It is a schematic diagram of the control apparatus of the engine which shows other embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view conceptually showing an engine control device E according to this embodiment.

  The engine 1 of this embodiment is a four-cycle gasoline engine for automobiles. As shown in FIG. 1, the engine 1 is configured to inject fuel into an intake passage 4 that feeds intake air into an internal combustion chamber 2, an exhaust passage 14 drawn out from the combustion chamber 2, an intake port, or the combustion chamber 2. A fuel injection device is provided. The openings of the intake passage 4 and the exhaust passage 14 to the combustion chamber 2 are opened and closed by valves.

  In this embodiment, a four-cylinder engine having four cylinders is assumed, but the present invention can be applied regardless of the number of cylinders.

  The intake passage 4 includes a throttle valve 5 that adjusts the flow passage area of the intake passage 4 toward the upstream side from an intake port that is a connecting portion to the combustion chamber 2, and an intake air cooling device that cools the intake air flowing through the intake passage 4. (Intercooler) 6, a compressor 11 of a supercharger (turbocharger) 10, and an air cleaner 7 and the like are provided on the upstream side thereof.

  The exhaust passage 14 includes a turbine 12 of the supercharger 10, a catalyst for removing harmful substances in the exhaust, and the like from the exhaust port, which is a connection portion to the combustion chamber 2, toward the downstream side. (Neighboring catalyst) 15, and further, a silencer 16 and the like are provided downstream thereof. In this embodiment, since a gasoline engine is used as the engine 1, a three-way catalyst or the like is used as the first exhaust purification unit 15. However, when the engine 1 is a diesel engine, the first exhaust purification unit 15 is oxidized. A catalyst, a diesel particulate filter, or the like is used.

  As shown in FIG. 1, the supercharger 10 includes a compressor 11 that is disposed in the intake passage 4 and supercharges intake air that is introduced into the combustion chamber, and a turbine 12 that is disposed in the exhaust passage 14 and rotates by exhaust energy. Is done. When the turbine 12 is rotated by the exhaust gas flowing through the exhaust passage 14, the rotation is transmitted to the compressor 11 in the intake passage 4. The intake air flowing in the intake passage 4 is supercharged by the rotation of the compressor 11.

  An exhaust bypass passage 13a that connects the upstream side and the downstream side of the turbine 12 in the exhaust passage 14 without passing through the turbine 12 in the exhaust passage 14, and an exhaust bypass valve that opens and closes the flow path of the exhaust bypass passage 13a. And a waste gate valve device 13 including 13b. If the exhaust bypass valve 13b is opened, the exhaust energy transmitted to the turbine 12 is reduced, and intake air supercharging is suppressed or stopped.

  A first exhaust gas recirculation device 20 is provided between the exhaust passage 14 and the intake passage 4. In this embodiment, the first exhaust gas recirculation passage 21 constituting the first exhaust gas recirculation device 20 causes the turbine 12 in the exhaust passage 14 and the downstream side of the first exhaust purification unit 15 and the upstream of the compressor 11 in the intake passage 4. The side is in communication. The first exhaust gas recirculation passage 21 includes an exhaust gas recirculation valve 22 that opens and closes the flow path of the first exhaust gas recirculation passage 21, and an exhaust gas recirculation gas cooler 23 that cools the exhaust gas recirculation gas upstream of the exhaust gas recirculation valve 22. Yes.

  If the exhaust gas recirculation valve 22 is opened, a part of the exhaust gas discharged from the combustion chamber 2 through the first exhaust gas recirculation passage 21 becomes an exhaust gas recirculation gas in the low pressure region upstream of the compressor 11 in the intake passage 4. Reflux.

  A vehicle equipped with the engine 1 includes an electronic control unit 50 for controlling the engine 1. The electronic control unit 50 gives commands necessary for engine control such as fuel injection by a fuel injection device provided in the intake passage 4 or the combustion chamber 2, supercharging pressure control, throttle valve 5 opening control, and the like. Do.

  In the intake passage 4, various pressure sensors for detecting the pressure in the intake passage 4 and other places and the amount of air flowing in the intake passage 4 are used as sensor devices for acquiring information necessary for controlling the engine 1. An air flow sensor or the like for detection is provided. Further, the exhaust passage 14 is provided with an exhaust temperature sensor for detecting the temperature of the exhaust gas as a sensor device for acquiring information necessary for controlling the engine 1. Further, the engine 1 is provided with a water temperature sensor that detects the temperature of cooling water that cools the cylinder block and the like, and a rotation speed sensor that detects the rotation speed of the crankshaft of the engine 1. In addition, a vehicle equipped with the engine 1 is provided with an accelerator opening sensor that detects the amount of depression of the accelerator, a vehicle speed sensor that detects the speed of the vehicle, and the like. Information on these various sensors can be acquired by the electronic control unit 50 through a cable. In the figure, a part of the cable is not shown.

  Between the downstream side of the turbine 12 in the exhaust passage 14 and the downstream side of the compressor 11 in the intake passage 4 or between the first exhaust recirculation passage 21 and the downstream side of the compressor 11 in the intake passage 4, the second exhaust gas is provided. A recirculation device 30 is provided. In this embodiment, the second exhaust gas recirculation passage 31 that constitutes the second exhaust gas recirculation device 30 causes the upstream side of the exhaust gas recirculation valve 22 in the first exhaust gas recirculation passage 21 and the downstream side of the throttle valve 5 in the intake air passage 4. Are communicating. Further, since the second exhaust gas recirculation passage 31 is connected to the downstream side (the intake passage 4 side) of the exhaust gas recirculation gas cooler 23, the exhaust gas cooled by the exhaust gas recirculation gas cooler 23 becomes the second exhaust gas recirculation gas as the exhaust gas recirculation gas. It flows into the passage 31.

  Reference numeral 31 a in the drawing indicates the starting end of the second exhaust gas recirculation passage 31. The second exhaust gas recirculation passage 31 is connected to the exhaust passage 14 and the first exhaust gas recirculation passage 21 at the start end 31a. Reference numeral 31 c in the drawing indicates the end of the second exhaust gas recirculation passage 31. The second exhaust gas recirculation passage 31 is connected to the intake passage 4 at the terminal end 31c.

  The second exhaust gas recirculation device 30 supercharges the exhaust gas in the second exhaust gas recirculation passage 31 in the middle of the second exhaust gas recirculation passage 31, and introduces the exhaust gas recirculation gas excess into the intake air as the exhaust gas recirculation gas. A feeder 33 is provided. The exhaust gas recirculation supercharger 33 is a low-pressure exhaust gas in the exhaust passage 14 downstream of the turbine 12 (in this embodiment, in the first exhaust recirculation passage 21 branched from the downstream side of the turbine 12 in the exhaust passage 14). Since the pressure is increased by supercharging the gas, it can be easily introduced into the high-pressure region on the downstream side of the compressor 11 in the intake passage 4.

  Therefore, in the engine 1 having a low pressure exhaust gas recirculation device such as the first exhaust gas recirculation device 20, the exhaust gas recirculation gas introduced into the intake passage 4 through the exhaust gas recirculation valve 22 is introduced into the combustion chamber 2. The exhaust gas recirculation gas can be introduced into the combustion chamber 2 at an early stage through the exhaust gas recirculation gas supercharger 33 so as to compensate for the response delay caused by the time lag until it is transported to the combustion chamber.

  As the exhaust gas recirculation gas supercharger 33, as in this embodiment, an electric supercharger that performs supercharging by driving a compressor by supplying electric power may be employed. A supercharger that performs supercharging by driving the compressor by rotation of the crankshaft of the engine 1 can be employed.

  In order to introduce the exhaust gas recirculation gas downstream of the throttle valve 5 in the intake passage 4 through the second exhaust gas recirculation device 30, the exhaust gas recirculation device 31 is disposed downstream of the exhaust gas recirculation gas supercharger 33. By opening the exhaust recirculation gas boost valve 32, the exhaust recirculation gas supercharged by the exhaust recirculation gas supercharger 33 can flow into the intake passage 4.

  At this time, if the supercharging introduction of the exhaust gas recirculation gas is performed excessively, the inside of the intake passage 4 becomes an exhaust gas recirculation gas excess state. Adjustment is made by opening / closing control of the gas boost valve 32.

  The electronic control unit 50 controls the first exhaust gas recirculation device 20 and the second exhaust gas recirculation device 30.

  In order to acquire information for performing the opening / closing control of the exhaust recirculation gas boost valve 32, the first recirculation gas supercharger 33 and the exhaust recirculation gas boost valve 32 in the second exhaust recirculation passage 31 are arranged between the first recirculation gas boost valve 32 and the exhaust recirculation gas boost valve 32. A pressure sensor a is arranged. A second pressure sensor b is disposed on the downstream side of the throttle valve 5 in the intake passage 4. The second pressure sensor b may be disposed on the downstream side of the boost valve 32 for the exhaust gas recirculation gas in the second exhaust gas recirculation passage 31.

  The exhaust recirculation gas boost valve 32 is controlled to open and close based on pressure information acquired by the first pressure sensor a and pressure information acquired by the second pressure sensor b. For example, the pressure difference between the pressure on the first pressure sensor a side and the pressure on the second pressure sensor b side is detected, and further, the flow velocity of the intake air on the downstream side of the throttle valve 5 in the intake passage 4 is detected by the air flow sensor. Thus, the opening degree of the exhaust gas recirculation gas boost valve 32 can be determined in consideration of the differential pressure and the flow velocity. The relationship between the differential pressure and flow velocity, the required torque, the number of revolutions of the engine 1, the vehicle speed, other operating conditions, and the opening degree of the exhaust recirculation gas boost valve 32 is stored by a map or the like provided in the electronic control unit 50. The opening degree of the exhaust gas recirculation gas boost valve 32 is determined based on the stored information.

  If the exhaust gas recirculation gas boost valve 32 is closed and the exhaust gas recirculation gas supercharger 33 is supercharged, the pressure on the upstream side of the exhaust gas recirculation gas boost valve 32, that is, the pressure on the first pressure sensor a side. Can be increased. Therefore, by increasing the pressure upstream of the exhaust gas recirculation gas boost valve 32 in advance, when the exhaust gas recirculation gas boost valve 32 is opened, the amount of exhaust gas recirculation gas introduced into the intake passage 4 can be reduced at once. Can be increased.

  By the way, the rotational operation of the exhaust gas recirculation gas supercharger 33 has a characteristic that it cannot be stopped immediately. In particular, when an electric supercharger is used as the exhaust gas recirculation gas supercharger 33, a certain amount of time is required until the electric supercharger completely stops after energization is stopped. Therefore, the exhaust gas return passage 36 that connects between the exhaust gas recirculation gas supercharger 33 in the second exhaust gas recirculation passage 31 and the boost valve 32 for exhaust gas recirculation gas and the downstream side of the turbine 12 in the exhaust passage 14. The exhaust gas return passage 36 is provided with an exhaust recirculation gas blow-off valve 34 that opens and closes the flow path of the exhaust gas return passage 36.

  Reference numeral 31 b in the drawing indicates a branch portion of the exhaust gas return passage 36 in the second exhaust gas recirculation passage 31. The branch portion 31 b is the start end of the exhaust gas return passage 36 and is located between the exhaust gas recirculation gas supercharger 33 and the exhaust gas recirculation gas boost valve 32. Further, reference numeral 31d in the figure indicates the end of the exhaust gas return passage 36. The exhaust gas return passage 36 is connected to the exhaust passage 14 at the terminal end 31d.

  Control for opening the exhaust gas recirculation gas blow-off valve 34 when the pressure on the downstream side of the exhaust gas recirculation gas supercharger 33 in the second exhaust gas recirculation passage 31 exceeds a predetermined value set in accordance with the operation state. The excess exhaust gas recirculation gas in the second exhaust gas recirculation passage 31 can be discharged to the exhaust gas passage 14 through the exhaust gas return passage 36.

  In this embodiment, the exhaust gas return passage 36 is connected to the downstream side of the first exhaust purification unit 15 in the exhaust passage 14. The surplus exhaust gas recirculation gas discharged through the exhaust gas return passage 36 merges with the exhaust gas in the exhaust passage 14, so that the exhaust gas is smoothly released into the atmosphere by the flow rate of the exhaust gas recirculation gas that merges. The effect can be expected.

  Under normal operating conditions, the exhaust gas recirculation valve 22 is opened, so that the exhaust gas recirculation gas is introduced into the low pressure region upstream of the compressor 11 in the intake passage 4. Such normal low-pressure exhaust gas recirculation device when the operation area is in a steady state without large acceleration / deceleration, or when it is in an operation area with acceleration / deceleration, but during moderate transient operation. Thus, the exhaust gas recirculation gas can be introduced into the intake air.

  In a transient operation where the required amount of exhaust gas recirculation increases rapidly, such as during rapid acceleration, the exhaust gas recirculation valve 22 is closed and the exhaust gas recirculation gas supercharger 33 is driven. At this time, the exhaust recirculation gas boost valve 32 is opened, and the exhaust recirculation gas blow-off valve 34 is closed. Thereby, the exhaust gas recirculation gas can be introduced into the high-pressure region on the downstream side of the compressor 11 in the intake passage 4 in a supercharged state.

  With such control, during transient operation in which the required amount of exhaust gas recirculation rapidly increases, the actual exhaust gas recirculation gas is set to the target value of the exhaust gas recirculation gas introduction amount set corresponding to the acceleration. It is possible to prevent the occurrence of a response delay state in which the increase in the introduction amount does not follow (a state where the actual introduction amount is small with respect to the target value of the introduction amount).

  Another embodiment is shown in FIG.

  2, in addition to the embodiment of FIG. 1, a residual gas discharge passage 41 that connects the downstream side of the compressor 11 in the intake passage 4 and the downstream side of the turbine 12 in the exhaust passage 14, and the residual gas thereof. A residual gas discharge device 40 having a residual gas discharge valve 42 for opening and closing the discharge passage 41 is provided. Since the configuration other than the addition of the residual gas discharge device 40 is basically the same as that of the embodiment of FIG. 1, detailed description thereof is omitted.

  The residual gas discharge device 40 can discharge a part of the residual gas in the intake passage 4 to the low pressure region on the downstream side of the turbine 12 in the exhaust passage 14 by opening the residual gas discharge valve 42.

  In this embodiment, the residual gas discharge passage 41 is connected to the intake passage 4 at the start end 41 a between the intake air cooling device 6 and the throttle valve 5 on the downstream side of the compressor 11 in the intake passage 4. The residual gas discharge passage 41 is connected to the exhaust passage 14 at a terminal end 41b downstream of the second exhaust purification unit (underfloor catalyst) 17 provided on the downstream side of the first exhaust purification unit 15 of the exhaust passage 14. Yes. Since the residual gas discharge passage 41 is connected to the upstream side of the throttle valve 5 having a relatively high pressure, the discharge of the residual gas from the intake passage 4 is smooth.

  With such control, during a transient operation in which the required amount of exhaust gas recirculation rapidly decreases, such as during rapid deceleration, the target value of the amount of exhaust gas recirculation gas set corresponding to the deceleration, It is possible to prevent occurrence of a response delay state (a state where the actual introduction amount is larger than the target value of the introduction amount) in which the actual reduction in the introduction amount of the exhaust gas does not follow.

  Yet another embodiment is shown in FIG.

  The embodiment of FIG. 3 changes the position of the connection portion of the second exhaust gas recirculation passage 31 to the exhaust passage 14 in the embodiment of FIG. 1, and accordingly, the exhaust gas recirculation gas cooler 23 of the first exhaust gas recirculation passage 21. Another exhaust gas recirculation gas cooler 37 is provided. Since the other configuration is basically the same as that of the embodiment of FIG. 1, detailed description thereof is omitted. Further, in the embodiment of FIG. 3, the residual gas discharge device 40 in the embodiment of FIG. 2 may be added.

  In the embodiment of FIG. 3, the second exhaust recirculation passage 31 is connected to the downstream side of the connection portion of the exhaust passage 14 with the first exhaust recirculation passage 21. Further, an exhaust gas recirculation gas cooler 37 for cooling the exhaust gas is provided in the middle of the second exhaust gas recirculation passage 31. That is, since the second exhaust gas recirculation passage 31 is directly connected to the exhaust passage 14 without going through the first exhaust gas recirculation passage 21, the exhaust gas recirculation gas cooler dedicated to the second exhaust gas recirculation device 30 is connected to the second exhaust gas recirculation passage 31. 37 is provided.

  As shown in the above embodiments, the start end 31a of the second exhaust gas recirculation passage 31 may be in the middle of the first exhaust gas recirculation passage 21 branched from the downstream side of the turbine 12 in the exhaust passage 14, or It may be downstream of the first exhaust purification unit 15. When the starting end 31 a of the second exhaust recirculation passage 31 is the exhaust passage 14, the connection portion of the second exhaust recirculation passage 31 to the exhaust passage 14 is from the connection portion between the first exhaust recirculation passage 21 and the exhaust passage 14. However, it is preferable that the downstream side of the exhaust passage 14 be disposed.

  Although the engine 1 of this embodiment is a four-cycle gasoline engine, the present invention is not limited to this embodiment, and the present invention can be applied to a diesel engine as well as other types of gasoline engines.

1 Engine 2 Combustion chamber 4 Intake passage 5 Throttle valve 6 Intake cooling device (intercooler)
10 Supercharger (turbocharger)
11 Compressor 12 Turbine 14 Exhaust passage 15 First exhaust purification unit 16 Silencer 17 Second exhaust purification unit 20 First exhaust gas recirculation device 21 First exhaust recirculation passage 22 Exhaust recirculation valve 23 Exhaust recirculation gas cooler 30 Second exhaust gas recirculation Circulator 31 Second exhaust recirculation passage 32 Exhaust recirculation gas boost valve 33 Exhaust recirculation gas supercharger 34 Exhaust recirculation gas blow-off valve 35 Exhaust recirculation gas introduction passage 36 Exhaust gas return passage 37 Exhaust recirculation gas cooler 40 Residual gas discharge device 41 Residual gas discharge passage 42 Residual gas discharge valve 50 Electronic control unit

Claims (7)

An intake passage and an exhaust passage leading to the combustion chamber;
A turbocharger including a compressor disposed in the intake passage and supercharging intake air to the combustion chamber, and a turbine disposed in the exhaust passage and rotated by exhaust gas to transmit the rotation to the compressor;
A throttle valve disposed downstream of the compressor in the intake passage;
A first exhaust gas recirculation passage connecting the downstream side of the turbine of the exhaust passage and the upstream side of the compressor of the intake passage, and an exhaust gas recirculation valve that opens and closes the first exhaust gas recirculation passage, and intakes a part of the exhaust gas. A first exhaust gas recirculation device to be introduced into the
A second exhaust gas recirculation passage for connecting the downstream side of the turbine in the exhaust passage or the upstream side of the exhaust gas recirculation valve in the first exhaust gas recirculation passage and the downstream side of the throttle valve in the intake air passage and the second exhaust gas recirculation thereof A second exhaust gas recirculation device provided with an exhaust gas recirculation supercharger that is arranged in a passage and supercharges exhaust gas in the second exhaust gas recirculation passage and introduces it into the intake air;
An engine control device comprising: The engine control device according to claim 1, further comprising an exhaust recirculation gas boost valve on a downstream side of the exhaust recirculation gas supercharger in the second exhaust recirculation passage. An exhaust gas return passage connecting between the exhaust gas recirculation gas supercharger of the second exhaust gas recirculation passage and the boost valve for the exhaust gas recirculation gas and a downstream side of the turbine of the exhaust passage;
An exhaust gas recirculation gas blow-off valve disposed in the exhaust gas return passage;
The engine control device according to claim 2. A first pressure sensor disposed between the exhaust gas recirculation gas supercharger in the second exhaust gas recirculation passage and the exhaust gas recirculation gas boost valve;
A second pressure sensor disposed downstream of the exhaust recirculation gas boost valve in the second exhaust recirculation passage or downstream of the throttle valve in the intake passage;
With
The opening / closing of the boost valve for exhaust gas recirculation gas is controlled based on pressure information acquired by the first pressure sensor and pressure information acquired by the second pressure sensor. Engine control device. An exhaust recirculation gas cooler is provided in the middle of the first exhaust recirculation passage,
The engine control device according to any one of claims 1 to 4, wherein the second exhaust gas recirculation passage is connected to a downstream side of the exhaust gas recirculation gas cooler of the first exhaust gas recirculation passage. The second exhaust gas recirculation passage is connected to a downstream side of the connection portion of the exhaust gas passage with the first exhaust gas recirculation passage;
The engine control device according to any one of claims 1 to 4, further comprising an exhaust recirculation gas cooler in the middle of the second exhaust recirculation passage. A residual gas discharge passage connecting the intake passage downstream of the compressor and upstream of the throttle valve and the exhaust passage downstream of the turbine, and a residual gas discharge valve for opening and closing the residual gas discharge passage; The engine control device according to any one of claims 1 to 6, further comprising a residual gas discharge device that discharges a part of the residual gas in the intake passage to the exhaust passage.

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