JP2005214063A - Internal combustion engine and operation controller of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To rapidly recirculate an exhaust gas to an intake side in stratified operation. <P>SOLUTION: This internal combustion engine 1 comprises a turbo 10 having a turbine 10t and a compressor 10c connected to the turbine 10t and pressurizing air, an exhaust gas bypass valve 12 flowing the exhaust gas of the internal combustion engine 1 to the downstream side of the turbine 10t after bypassing the turbine 10t, an intake bypass valve 11 supplying the air to the internal combustion engine 1 after bypassing the compressor 10c, and an EGR valve 13 extracting the exhaust gas of the internal combustion engine 1 from the downstream side of the turbine 10 and recirculating it to the intake side of the internal combustion engine 1. When the operation of the internal combustion engine is transferred from a homogeneous lean operation in combination with supercharging to the stratified operation, the air is supplied to the internal combustion engine 1 after bypassing the compressor 10c by opening at least the intake bypass valve 11, and the exhaust gas of the internal combustion engine 1 is recirculated to the intake side by the EGR valve 13. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a reciprocating internal combustion engine that can be operated by switching between a homogeneous lean operation and a stratified operation, and more particularly, an internal combustion engine that can quickly return exhaust gas to the intake side when switching from a homogeneous lean operation to a stratified operation. And an operation control apparatus for an internal combustion engine.

  Reciprocating internal combustion engines are widely used in vehicles such as passenger cars and trucks. In order to improve the performance of such an internal combustion engine, air with a pressure higher than the atmospheric pressure is supplied to the internal combustion engine by a supercharger to improve the output, or fuel is injected directly into the cylinder for stratified combustion. Thus, a technique for reducing fuel consumption is used. Patent Document 1 discloses an internal combustion engine that includes an in-cylinder injector that injects fuel into an intake passage, and an in-cylinder injector that injects fuel into a cylinder, and further includes a supercharging device, and is configured to respond to supercharging pressure. Thus, a technique for changing the share ratio of the fuel injection amount between the in-cylinder injector and the out-cylinder injector is disclosed.

JP 11-351041 A

  By the way, in recent internal combustion engines, a combination of supercharging in homogeneous lean combustion expands the lean combustion region, and further switches to stratified operation in regions where the load and engine speed are low, thereby reducing fuel consumption Has been made. When realizing such a technique, it is necessary to suppress the generation of NOx by returning the exhaust gas of the internal combustion engine to the intake side during the stratified operation. However, since the supercharging pressure does not decrease quickly, there is a problem that it is difficult to quickly recirculate the exhaust gas to the intake side when switching the stratified operation. Patent Document 1 does not mention any such problems, and the problem can be solved by changing the share ratio of the fuel injection amount between the in-cylinder injector and the out-cylinder injector according to the supercharging pressure. Can not.

  Therefore, the present invention has been made in view of the above, and when switching from a homogeneous combustion operation using supercharging to a stratified operation, the internal combustion engine capable of quickly returning exhaust gas to the intake side and the operation of the internal combustion engine An object is to provide a control device.

  In order to solve the above-described problems and achieve the object, this internal combustion engine is an internal combustion engine that can switch between a homogeneous lean operation using supercharging and a stratified operation depending on operating conditions, and is driven by exhaust gas. A turbocharger configured to include a turbine and a compressor connected to the turbine to pressurize the air; and an exhaust bypass unit that causes the exhaust of the internal combustion engine to flow downstream of the turbine after bypassing the turbine Intake bypass means for supplying air to the internal combustion engine after bypassing the compressor; and exhaust recirculation means for extracting the exhaust of the internal combustion engine from the downstream of the turbine and returning it to the intake side of the internal combustion engine When the transition from homogeneous lean operation using supercharging to stratified operation to stratified operation is carried out, at least the compressor is used by the intake bypass means. Supplies air to the internal combustion engine from bypass the service, and wherein the recirculating exhaust of the internal combustion engine by the exhaust gas recirculation means.

  When this internal combustion engine shifts from a homogeneous lean operation with supercharging to a stratified operation without supercharging, at least the compressor of the supercharging means is bypassed and air is supplied to the internal combustion engine, and the exhaust is sent to the intake side. Reflux. As a result, the exhaust gas can be recirculated to the intake side with the intake pipe pressure substantially equal to the atmospheric pressure. As a result, the exhaust gas can be quickly returned to the intake side during the transition.

  In the internal combustion engine according to the present invention, when the internal combustion engine shifts from the homogeneous lean operation using supercharging to the stratified operation, the exhaust gas from the internal combustion engine is further downstream from the turbine by the exhaust bypass means. It is characterized by flowing to.

  In this internal combustion engine, the turbine of the supercharging means is further bypassed to guide the exhaust downstream, and then the exhaust is recirculated to the intake side. As a result, the exhaust gas can be recirculated to the intake side while the pressure loss in the turbine is substantially zero. As a result, when shifting from the homogeneous lean operation using supercharging to the stratified operation, the exhaust gas can be quickly returned to the intake side.

  An internal combustion engine according to the present invention is an internal combustion engine capable of switching between a homogeneous lean operation using supercharging and a stratified operation depending on operating conditions, and is connected to the turbine driven by exhaust gas. A supercharging means comprising a compressor for pressurizing air; an exhaust bypass means for allowing the exhaust of the internal combustion engine to flow downstream of the turbine after bypassing the turbine; and bypassing the compressor; Intake bypass means for supplying air to the internal combustion engine, and recirculation means for extracting the exhaust of the internal combustion engine from upstream of the turbine and returning the exhaust of the internal combustion engine to the intake side of the internal combustion engine, When shifting from homogeneous lean operation with supercharging to stratified operation, the compressor is bypassed by the intake bypass means before Supplies air to the internal combustion engine, while introducing exhaust of the internal combustion engine to the turbine, and wherein the recirculating exhaust of the internal combustion engine by the exhaust gas recirculation means.

  In this internal combustion engine, the exhaust gas is recirculated from the upstream side of the turbine included in the supercharging means to the intake side. When the exhaust gas is recirculated to the intake side during the transition from the homogeneous lean operation using supercharging to the stratified operation, the supercharging means bypasses the compressor of the supercharging means and supplies the air to the internal combustion engine. The exhaust is led to the turbine. By doing so, the pressure of the exhaust gas to be recirculated is larger than the air pressure on the intake side due to the resistance of the turbine, so that the exhaust gas can be quickly recirculated to the intake side.

  An internal combustion engine according to the present invention includes a port injection valve that injects fuel into an intake port of the internal combustion engine and a cylinder injection valve that injects fuel into a cylinder of the internal combustion engine. In the homogeneous lean operation using supercharging, the fuel is injected from the port injection valve, and in the stratified operation, the fuel is injected from the in-cylinder injection valve.

  An internal combustion engine operation control apparatus according to the present invention is capable of switching between a homogeneous lean operation using supercharging and a stratified operation depending on operating conditions, and is connected to a turbine driven by exhaust and the turbine. It is used for operation control of an internal combustion engine comprising supercharging means configured to include a compressor for pressurizing air and exhaust gas recirculation means for extracting the exhaust gas of the internal combustion engine from the downstream of the turbine and returning it to the intake side. When the internal combustion engine shifts from the homogeneous combustion operation to the stratified operation, at least the exhaust gas recirculation pressure control unit for supplying air to the internal combustion engine after bypassing the compressor and the exhaust gas recirculation means. And an exhaust gas recirculation operation unit that recirculates exhaust gas from the engine.

  The internal combustion engine operation control device bypasses at least the compressor of the supercharging means when the operation state of the internal combustion engine is shifted from the homogeneous lean operation with supercharging to the stratified operation without supercharging. Air is supplied to the engine and exhaust gas is recirculated to the intake side. As a result, the exhaust gas can be recirculated to the intake side with the intake pipe pressure substantially equal to the atmospheric pressure. As a result, the exhaust gas can be quickly returned to the intake side during the transition.

  An internal combustion engine operation control apparatus according to the present invention is capable of switching between a homogeneous lean operation using supercharging and a stratified operation depending on operating conditions, and is connected to a turbine driven by exhaust and the turbine. It is used for operation control of an internal combustion engine comprising supercharging means configured to include a compressor for pressurizing air and exhaust gas recirculation means for extracting the exhaust gas of the internal combustion engine from the upstream side of the turbine and returning it to the intake side. When the internal combustion engine shifts from the homogeneous combustion operation to the stratified operation, at least the compressor is bypassed and then the air is supplied to the internal combustion engine and the exhaust gas that introduces the exhaust gas of the internal combustion engine to the turbine A recirculation pressure control unit; and an exhaust gas recirculation operation unit that recirculates exhaust gas of the internal combustion engine by the exhaust gas recirculation unit. And wherein the Rukoto.

  This internal combustion engine operation control apparatus is used for operation control of an internal combustion engine that recirculates exhaust gas to the intake side from the upstream side of a turbine provided in the supercharging means. When the operation state of the internal combustion engine is shifted from the homogeneous lean operation using supercharging to the stratified operation, the compressor of the supercharging means is bypassed and air is supplied to the internal combustion engine, and the turbine of the supercharging means is supplied. The exhaust is guided and the exhaust is recirculated to the intake side. By doing so, the pressure of the exhaust gas to be recirculated is larger than the air pressure on the intake side due to the resistance of the turbine, so that the exhaust gas can be quickly recirculated to the intake side.

  According to the internal combustion engine of the present invention, when switching from homogeneous combustion operation to stratified operation, there is an effect that exhaust gas can be quickly recirculated to the intake side.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by the Example demonstrated below. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same. The present invention can be preferably applied to a reciprocating internal combustion engine, and is particularly preferable for an internal combustion engine mounted on a vehicle such as a passenger car, a bus, or a truck.

  The internal combustion engine according to the first embodiment is an internal combustion engine that includes a supercharging unit and can switch between a homogeneous lean operation and a stratified operation, and a recirculation unit that recirculates exhaust gas to the intake side is provided from the downstream of the turbine. It is characterized in that at least the intake bypass means is opened when the exhaust gas is recirculated and when the homogeneous lean operation is shifted to the stratified operation.

  FIG. 1 is an overall configuration diagram of an internal combustion engine according to a first embodiment. The internal combustion engine 1 according to the embodiment is a spark ignition reciprocating internal combustion engine using gasoline as fuel. The number of cylinders of the internal combustion engine 1 is not particularly limited. The internal combustion engine 1 includes an in-cylinder injection valve 3 for directly injecting fuel F into the combustion chamber 1b in the cylinder 1s. The fuel F injected from the in-cylinder injection valve 3 forms a fuel spray Fm in the combustion chamber 1b in the cylinder 1s, and forms an air-fuel mixture with air introduced from the intake port 22 into the combustion chamber 1b. This air-fuel mixture is ignited and burned by a spark plug 9 which is a spark ignition means, and the pressure of the combustion gas causes the piston 7 to reciprocate.

  The internal combustion engine 1 also includes a port injection valve 5 that injects fuel F into the intake port 22 to form a fuel spray Fm in the intake port 22. The in-cylinder injection valve 3 is preferably used mainly during the stratified operation, but can also be used for homogeneous lean combustion if the fuel spray is refined or the fuel injection timing is changed. Therefore, in order to realize the internal combustion engine of the first embodiment, at least the in-cylinder injection valve 3 may be provided. However, when the fuel F is injected into the intake port 22, the air and the fuel F are sufficiently mixed, so that an air-fuel mixture suitable for homogeneous lean combustion can be formed. For this reason, in the internal combustion engine 1 according to the first embodiment, the in-cylinder injection valve 3 is used during stratified operation, and the port injection valve 5 is used during homogeneous lean combustion.

  The internal combustion engine 1 includes supercharging means. In this embodiment, a turbocharger (hereinafter referred to as turbo) 10 driven by the exhaust of the internal combustion engine 1 is provided as a supercharging means. The turbo 10 includes a compressor 10c, a turbine 10t that drives the compressor 10c by exhaust of the internal combustion engine 1, and a rotary shaft 10s that couples both. Exhaust gas from the internal combustion engine 1 is supplied to the turbine 10t from an exhaust manifold (turbine upstream exhaust passage) 23, and is driven by the exhaust gas. In addition to the turbo 10, the so-called electric assist turbo can be used as the supercharging means.

  Here, the downstream of the turbine 10t means the downstream side of the flow of exhaust gas passing through the turbine 10t. And the upstream of the turbine 10t means the upstream side of the flow of the exhaust gas flowing into the turbine 10t. Further, when referring to upstream or downstream, upstream or downstream is determined based on the flow of air supplied to the internal combustion engine 1 or exhaust gas discharged from the internal combustion engine. Further, the intake side of the internal combustion engine 1 refers to the upstream side of the intake valve 4 of the internal combustion engine 1, and the exhaust side of the internal combustion engine 1 refers to the downstream side of the exhaust valve 6 of the internal combustion engine 1 ( The same applies below).

  The internal combustion engine 1 according to the first embodiment can switch between supercharging and non-supercharging by the supercharging means. For this reason, the intake bypass passage 20b bypasses the compressor 10c of the turbo 10 and is connected between the compressor upstream intake passage 20 and the compressor downstream intake passage 21. An intake bypass valve 11 serving as an intake bypass means is provided in the middle of the intake bypass passage 20b. When supercharging is not performed, the intake air bypass valve 11 is opened to connect the compressor upstream intake passage 20 and the compressor downstream intake passage 21 to bypass the compressor 10c of the turbo 10 and allow air to flow into the internal combustion engine 1. Can be supplied. On the other hand, when supercharging is used together, the air can be supplied to the internal combustion engine 1 by guiding the air to the compressor 10 c of the turbo 10 by closing the intake bypass valve 11.

  Further, the internal combustion engine 1 performs so-called EGR (Exhaust Gas Recirculation) in which the exhaust gas is recirculated to the intake side of the internal combustion engine 1 during the stratified operation. For this reason, an exhaust gas recirculation passage 26 connecting the turbine downstream exhaust passage 24 and the compressor downstream intake passage 21 is provided. The exhaust gas recirculation passage 26 is provided with an EGR valve 13 as exhaust gas recirculation means. And by opening this, the exhaust gas of the internal combustion engine 1 can be guided to the intake side. In this example, exhaust gas is extracted from the upstream side of the catalyst 17.

  An engine ECU 30 (Electronic Control Unit) that controls the operation of the internal combustion engine 1 acquires outputs from an accelerator opening sensor 41, an air flow sensor 43, and other various sensors attached to the internal combustion engine 1, and operates the internal combustion engine 1. To control. The internal combustion engine 1 also includes a throttle valve 14 that is opened and closed by an actuator 45. The engine ECU 30 acquires the output from the accelerator opening sensor 41 and sends a control signal to the actuator 45 in consideration of whether the internal combustion engine 1 is stratified operation or homogeneous combustion operation. The degree is given to the throttle valve 14. At the same time, the engine ECU 30 calculates the amount of fuel supplied to the internal combustion engine 1 from the outputs from the accelerator opening sensor 41 and the air flow sensor 43. Further, the amount of exhaust gas recirculated to the intake side is determined according to the operating state of the internal combustion engine 1.

  Next, the operation of the internal combustion engine 1 will be described. FIG. 2 is an explanatory diagram of a combustion region during operation of the internal combustion engine according to the first embodiment. In FIG. 2, λ is an excess air ratio, and λ = 1 is stoichiometric. R / L is the running resistance. The internal combustion engine 1 according to the first embodiment can switch between a homogeneous lean operation and a stratified operation. As shown in FIG. 2, the homogeneous lean operation and the stratified operation are switched according to the load KL of the internal combustion engine 1 and the engine speed NE. Specifically, in the region of low load and low rotation speed, the operation is switched from homogeneous lean operation to stratified operation.

  Further, when the internal combustion engine 1 according to the first embodiment performs the homogeneous lean operation, the turbo 10 is used to supercharge the air. As a result, the excess air ratio λ greatly exceeds 1. Note that air is supercharged not only in the homogeneous lean operation but also in the region of excess air ratio λ = 1 and WOT (Wide Open Throttle: high load region). On the other hand, during stratified operation, in principle, the fuel is directly injected from the in-cylinder injection valve 3 into the combustion chamber 1b in the cylinder 1s without supercharging. In the stratified operation, since the exhaust gas is recirculated to the intake side, the excess air ratio λ is smaller than that in the homogeneous lean operation.

  In the homogeneous lean operation, the air from which the dust has been removed by the air cleaner 15 is introduced into the compressor 10c of the turbo 10 after the flow rate is measured by the air flow sensor 43 provided in the compressor upstream intake passage 20. Then, after being compressed by the compressor 10 c and passing through the intercooler 16 through the compressor downstream side intake passage 21, the air amount is adjusted by the throttle valve 14. The air that has passed through the throttle valve 14 is supplied to the combustion chamber 1b of the cylinder 1s through the intake port 22. At this time, during the homogeneous lean operation, the fuel F is supplied from the port injection valve 5 into the intake port 22 to form an air-fuel mixture.

  The air-fuel mixture supplied to the combustion chamber 1b of the cylinder 1s is ignited and burned by the spark plug 9 to drive the piston 7. The exhaust gas after driving the piston 7 is discharged to the exhaust manifold 23 and then supplied to the turbine 10t of the turbo 10 to drive it. The turbine 10t drives the compressor 10c and supplies compressed air to the internal combustion engine 1. Exhaust gas after driving the turbine 10t is sent to the catalyst 17 through the turbine downstream side exhaust passage 24, purified there, and then exhausted to the atmosphere through the catalyst downstream side exhaust passage 25.

  In the stratified operation, the flow rate of the air from which dust has been removed by the air cleaner 15 is measured by an air flow sensor 43 provided in the compressor upstream intake passage 20. In the case of stratified combustion, air is supplied to the internal combustion engine 1 from the intake bypass passage 20b without being used for the turbo 10. Therefore, by opening the intake bypass valve 11, the compressor upstream intake passage 20 and the compressor downstream intake passage 21 are communicated with each other. Thereby, the compressor 10c of the turbo 10 is bypassed and air is supplied to the internal combustion engine 1.

  The amount of air that has bypassed the compressor 10 c is adjusted by the throttle valve 14 provided in the compressor downstream side intake passage 21. The air that has passed through the throttle valve 14 is supplied to the combustion chamber 1b of the cylinder 1s through the intake port 22. Fuel F is injected from the in-cylinder injection valve 3 into the air supplied to the combustion chamber 1b of the cylinder 1s. The fuel F is wound up toward the spark plug 9 in the combustion chamber 1 b and forms a rich air-fuel mixture layer in the vicinity of the spark plug 9. The air-fuel mixture layer is ignited by the spark plug 9 and burns to drive the piston 7.

  Exhaust gas after driving the piston 7 is discharged to the exhaust manifold 23. In the stratified operation, the exhaust gas is recirculated to the intake side to lower the combustion temperature and suppress the generation of NOx. Therefore, the exhaust bypass valve 12 (so-called waste gate), which is an exhaust bypass means, is opened to guide the exhaust gas from the internal combustion engine 1 to the exhaust bypass passage 23b. Exhaust gas that has passed through the exhaust bypass passage 23 b flows to the turbine downstream exhaust passage 24. Here, since the EGR valve 13 serving as the exhaust gas recirculation means is opened, the exhaust gas flowing through the turbine downstream exhaust passage 24 is supplied to the compressor downstream intake passage 21 serving as the intake side through the exhaust gas recirculation passage 26. .

  When turbocharging is not performed by the turbo 10, the pressure in the compressor downstream intake passage 21 (hereinafter referred to as intake pipe pressure) Pb is smaller than the pressure in the turbine downstream exhaust passage 24 (hereinafter referred to as turbine downstream exhaust pressure) P6. The exhaust can be recirculated to the intake side. However, when turbocharging is performed by the turbo 10, the intake pipe pressure Pb may be larger than the turbine downstream exhaust pressure P6. In such a case, since the exhaust cannot be recirculated to the intake side, the exhaust can be recirculated to the intake side during the stratified operation when Pb <P6. In the first embodiment, in principle, supercharging is stopped during stratified operation, and exhaust gas is recirculated to the intake side, thereby reducing NOx generated during stratified operation.

  When shifting from a homogeneous lean operation with supercharging to a stratified operation without supercharging, a large amount of NOx is generated during the stratified operation unless the exhaust gas is recirculated to the intake side at the same time. On the other hand, since the turbine 10t of the turbo 10 is rotating at an extremely high rotation speed (tens of thousands rpm to tens of thousands rpm), it is extremely difficult to stop the supercharging by suddenly dropping the rotation. For this reason, in Example 1, when shifting from the homogeneous lean operation to the stratified operation, the intake bypass valve 11 and the exhaust bypass valve 12 are opened.

  When a mechanical supercharger (so-called supercharger) driven by power extracted from the crankshaft of the internal combustion engine 1 is used as the supercharging means, the exhaust gas from the internal combustion engine 1 is not used. Just open. Further, unless the pressure in the compressor downstream side intake passage 21 is lower than the pressure in the turbine downstream side exhaust passage 24, the exhaust does not recirculate to the intake side. Further, neither the pressure in the compressor downstream side intake passage 21 nor the pressure in the turbine downstream side exhaust passage 24 becomes smaller than the atmospheric pressure. Therefore, in order to recirculate the exhaust gas when shifting to the stratified operation, it is necessary to open at least the intake bypass valve 11 and bring the pressure in the turbine downstream side exhaust passage 24 close to atmospheric pressure.

  By opening the intake bypass valve 11, the intake pipe pressure Pb is made substantially equal to the atmospheric pressure P0. Further, by opening the exhaust bypass valve 12, the pressure loss in the turbine 10 t is made substantially zero, and the exhaust gas in a state where the pressure is hardly lowered is introduced into the turbine downstream side exhaust passage 24. Thus, when the exhaust gas is recirculated to the intake side, the state of the intake pipe pressure Pb <the turbine downstream side exhaust pressure P6 can be quickly created. As a result, when shifting from the homogeneous lean operation to the stratification operation, the exhaust gas can be quickly recirculated to the intake side, so that the amount of NOx generated can be extremely reduced from the start of the stratification operation. Further, when the exhaust gas of the internal combustion engine 1 is recirculated to the intake side, the exhaust gas bypass valve 12 is opened to bypass the turbine 10t, so that the exhaust resistance of the internal combustion engine 1 can be reduced. As a result, the fuel consumption of the internal combustion engine 1 can be reduced.

  Next, an internal combustion engine operation control apparatus according to Embodiment 1 will be described. FIG. 3 is an explanatory diagram illustrating a configuration of the operation control apparatus for the internal combustion engine according to the first embodiment. Here, the internal combustion engine start control method according to the first embodiment can be realized by the operation control device 50 for an internal combustion engine of the present invention. The operation control device 50 for the internal combustion engine is built into the engine ECU 30. Separately from the engine ECU 30, an internal combustion engine operation control device 50 according to this embodiment may be prepared and connected to the engine ECU 30. When realizing the internal combustion engine start control method according to this embodiment, the control function of the internal combustion engine 1 provided in the engine ECU 30 may be configured so that the operation control device 50 of the internal combustion engine can be used.

  The internal combustion engine operation control device 50 includes an operation state determination unit 51, an exhaust gas recirculation pressure control unit 52, and an exhaust gas recirculation operation unit 53. These are the parts that execute the start control method for the internal combustion engine according to this embodiment. The operation state determination unit 51, the exhaust gas recirculation pressure control unit 52, and the exhaust gas recirculation operation unit 53 are connected via an input / output port (I / O) 39 of the operation control device 50 of the internal combustion engine. Thus, the operation state determination unit 51, the exhaust gas recirculation pressure control unit 52, and the exhaust gas recirculation operation unit 53 are configured to exchange data in both directions. Note that data may be transmitted and received in one direction as required in the apparatus configuration (the same applies hereinafter).

  The operation control device 50 of the internal combustion engine, the main processing unit 30p of the engine ECU 30, and the storage unit 30m are connected via an input / output port (I / O) 39 provided in the engine ECU 30, and are mutually connected. Data can be exchanged. Thereby, the operation control device 50 of the internal combustion engine acquires the load of the internal combustion engine 1 and the engine speed other than the engine ECU 30 and other operation control data of the internal combustion engine, or controls the operation control device 50 of the internal combustion engine. It is possible to interrupt the operation control routine of the internal combustion engine.

  In addition, the input / output port (I / O) 39 is connected to various sensors for acquiring information related to the operating state of the internal combustion engine 1, such as an accelerator opening sensor 41, a rotation speed sensor 42, an air flow sensor 43. As a result, the engine ECU 30 and the operation control device 50 for the internal combustion engine can acquire information necessary for operation control of the internal combustion engine 1. An intake bypass valve 11, an exhaust bypass valve 12, and an EGR valve 13 are connected to the input / output port (I / O) 39, and the exhaust gas recirculation pressure control unit 52 of the operation control device 50 of the internal combustion engine and the engine ECU 30 are connected. These are configured to be opened and closed by a control signal from the main processing unit 30p.

  The storage unit 30m stores a computer program including a processing procedure of the start control method for the internal combustion engine according to this embodiment, a data map of a fuel injection amount used for operation control of the internal combustion engine 1, and the like. Here, the storage unit 30m can be configured by a volatile memory such as a RAM (Random Access Memory), a nonvolatile memory such as a flash memory, or a combination thereof. Further, the operation control device 50 of the internal combustion engine and the main processing unit 30p of the engine ECU 30 can be configured by a memory and a CPU.

  The computer program can realize the processing procedure of the start control method of the internal combustion engine according to this embodiment, in combination with the computer program already recorded in the operating state determination unit 51, the exhaust gas recirculation pressure control unit 52, and the like. There may be. The internal combustion engine operation control device 50 realizes the functions of the operation state determination unit 51, the exhaust gas recirculation pressure control unit 52, and the exhaust gas recirculation operation unit 53 using dedicated hardware instead of the computer program. May be. Next, a procedure for realizing the internal combustion engine start control method according to this embodiment using the operation control device 50 for the internal combustion engine will be described. In this description, please refer to FIGS.

  FIG. 4 is a flowchart illustrating a procedure of the internal combustion engine start control method according to the first embodiment. When executing the operation control of the internal combustion engine according to the first embodiment, the operation state determination unit 51 of the operation control device 50 for the internal combustion engine determines that the internal combustion engine 1 is in a homogeneous lean operation from the engine speed NE and the load KL of the internal combustion engine 1. It is determined whether or not the vehicle is being operated (step S101). When the internal combustion engine 1 is not operated in the homogeneous lean operation (step S101; No), the operation state of the internal combustion engine 1 is monitored again.

  When the internal combustion engine 1 is operated in the homogeneous lean operation (step S101; Yes), the operation state determination unit 52 determines whether the internal combustion engine 1 shifts to the stratified operation from the engine speed NE and the load KL of the internal combustion engine 1. It is determined whether or not (step S102). When the internal combustion engine 1 does not shift to the stratified operation (step S102; No), the operation state of the internal combustion engine 1 is monitored again.

  When the internal combustion engine 1 shifts to the stratified operation (step S102; Yes), the exhaust gas recirculation pressure control unit 52 opens the intake bypass valve (A / B valve) 11 and the exhaust bypass valve (E / B valve) 12 (step). S103). Thereby, the state of intake pipe pressure Pb <turbine downstream exhaust pressure P6 can be achieved instantaneously. Then, the exhaust gas recirculation operation unit 53 opens the EGR valve 13 (step S104) to recirculate the exhaust gas of the internal combustion engine 1 to the intake side. At the same time, the main processing unit 30p of the engine ECU 30 injects fuel from the in-cylinder injection valve 3 with the fuel injection amount obtained based on information from the airflow sensor 43, the accelerator opening sensor 41, etc., and shifts to the stratified operation. .

  As described above, according to the first embodiment, when shifting from the homogeneous lean operation using supercharging to the stratified operation without supercharging, the intake bypass valve is opened and the exhaust bypass valve is opened. As a result, the intake pipe pressure can be made substantially equal to the atmospheric pressure, the pressure loss at the turbine can be made almost zero, and the exhaust gas in a state where the pressure has hardly decreased can be recirculated to the intake side. As a result, when shifting from the homogeneous lean operation using supercharging to the stratification operation, the exhaust gas can be quickly returned to the intake side, so that the amount of NOx generated can be extremely reduced from the start of the stratification operation. . Further, when the exhaust gas of the internal combustion engine is recirculated to the intake side, the exhaust bypass valve is opened to bypass the turbine, so that the exhaust resistance of the internal combustion engine can be reduced. As a result, the fuel consumption of the internal combustion engine can be reduced.

  The internal combustion engine according to the second embodiment has substantially the same configuration as the internal combustion engine according to the first embodiment, except that the exhaust gas is recirculated from the upstream side of the turbine provided in the turbo to the intake side. Since other configurations are the same as those of the first embodiment, the description thereof is omitted, and the same components are denoted by the same reference numerals. FIG. 5 is an overall configuration diagram of the internal combustion engine according to the second embodiment. FIG. 6 is a flowchart illustrating the procedure of the internal combustion engine start control method according to the second embodiment. The operation control method for the internal combustion engine according to the second embodiment can be realized by the operation control device 50 for the internal combustion engine according to the first embodiment.

  The internal combustion engine 1 ′ also performs so-called EGR (Exhaust Gas Recirculation) in which exhaust gas is recirculated to the intake side of the internal combustion engine 1 during stratified operation. For this reason, an exhaust gas recirculation passage 26 ′ connecting the turbine upstream side exhaust passage 23 and the compressor downstream side intake passage 21 is provided. The exhaust gas recirculation passage 26 'is provided with an EGR valve 13 as exhaust gas recirculation means. By opening this, the exhaust gas from the internal combustion engine 1 can be guided to the intake side.

  In stopping the supercharging when shifting from the homogeneous lean operation to the stratified operation and returning the exhaust gas to the intake side, the intake bypass valve 11 is opened and the exhaust bypass valve 12 is kept closed. By doing so, the turbine upstream exhaust pressure P5 becomes larger than the turbine downstream exhaust pressure P6 due to the resistance of the turbine 10t. Further, by opening the intake bypass valve 11, the intake pipe pressure Pb becomes atmospheric pressure (P0). As a result, the pressure of the recirculated exhaust gas at the exhaust recirculation passage inlet 26i ′, that is, the turbine upstream exhaust pressure P5> the intake pipe pressure Pb is satisfied, so that the exhaust gas of the internal combustion engine 1 can be recirculated to the intake side during the stratified operation. .

  As described above, when the exhaust gas is recirculated from the turbine upstream side exhaust passage 23, the pressure difference (P5-Pb) between the turbine upstream side exhaust pressure P5 and the intake pipe pressure Pb is always positive. As a result, the exhaust gas is stably recirculated to the intake side, and generation of NOx can be suppressed. Further, since the pressure difference (P5-Pb) is always positive, when the EGR valve 13 is opened, the exhaust gas quickly returns to the intake side, and the effect of reducing NOx can be obtained quickly.

  Further, in the internal combustion engine 1 ′ according to the second embodiment, after the shift to the stratified operation, for a predetermined time until the intake pipe pressure Pb sufficiently decreases, the exhaust bypass valve 12 is closed and the exhaust gas is recirculated to the intake side. Thereafter, the exhaust bypass valve 12 may be opened. As a result, the difference between the turbine upstream side exhaust pressure P5 and the intake pipe pressure Pb can be increased until the intake pipe pressure Pb is sufficiently reduced (for example, to near atmospheric pressure). It can return to the intake side. Then, after the exhaust gas starts to recirculate stably to the intake side, the exhaust gas bypass valve 12 is opened to reduce the turbine upstream exhaust pressure P5 in the turbine upstream exhaust passage 23, so that the exhaust resistance of the internal combustion engine 1 is reduced. Lowering can reduce fuel consumption.

  Further, in the internal combustion engine 1 ′ according to the second embodiment, the exhaust gas is recirculated to the intake side while supercharging at a low pressure even in the stratified operation by adjusting the opening degree without opening the intake bypass valve 11 completely. You can also At this time, the supercharging pressure for the internal combustion engine 1 is adjusted so as to satisfy the relationship of intake pipe pressure Pb <turbine upstream exhaust pressure P5.

  Next, a procedure for operation control of the internal combustion engine according to the second embodiment will be described. First, the operation state determination unit 51 of the operation control device 50 for the internal combustion engine determines whether the internal combustion engine 1 is operated in a homogeneous lean operation from the engine speed NE and the load KL of the internal combustion engine 1 (step S201). ). When the internal combustion engine 1 is not operated in the homogeneous lean operation (step S201; No), the operation state of the internal combustion engine 1 is monitored again.

  When the internal combustion engine 1 is operated in the homogeneous lean operation (step S201; Yes), the operation state determination unit 52 determines whether the internal combustion engine 1 shifts to the stratified operation from the engine speed NE and the load KL of the internal combustion engine 1. It is determined whether or not (step S202). When the internal combustion engine 1 does not shift to the stratified operation (step S202; No), the operation state of the internal combustion engine 1 is monitored again. When the internal combustion engine 1 shifts to the stratified operation (step S202; Yes), the exhaust gas recirculation pressure control unit 52 opens the intake bypass valve (A / B valve) 11 and opens the exhaust bypass valve (E / B valve) 12. Close (step S203). Thereby, the state of intake pipe pressure Pb <turbine downstream exhaust pressure P6 can be achieved instantaneously. Then, the exhaust gas recirculation operation unit 53 opens the EGR valve 13 (step S204) and recirculates the exhaust gas of the internal combustion engine 1 to the intake side. At the same time, the main processing unit 30p of the engine ECU 30 injects fuel from the in-cylinder injection valve 3 with the fuel injection amount obtained based on information from the airflow sensor 43, the accelerator opening sensor 41, etc., and shifts to the stratified operation. .

  As described above, in the internal combustion engine according to the second embodiment, the exhaust gas is recirculated from the turbo upstream exhaust passage to the intake side. When shifting from the homogeneous lean operation using supercharging to the stratified operation not using supercharging, when returning the exhaust gas to the intake side, the intake bypass valve 12 is opened and the exhaust bypass valve 12 is kept closed. To do. By doing so, the pressure of the recirculated exhaust gas at the inlet of the exhaust gas recirculation passage can always be higher than the intake pipe pressure due to the resistance of the turbine. Therefore, during stratified operation, the exhaust gas of the internal combustion engine is stably recirculated to the intake side. Thus, the generation of NOx can be suppressed. Moreover, since the pressure of the exhaust gas to be recirculated is always higher than the intake pipe pressure, the pressure of the exhaust gas is higher than the intake pipe pressure. As a result, when the EGR valve is opened, the exhaust gas quickly returns to the intake side, and the effect of reducing NOx can be obtained quickly.

  As described above, the internal combustion engine according to the present invention is useful for an internal combustion engine capable of switching between a homogeneous lean operation and a stratified operation in combination with supercharging. In particular, when shifting to a stratified operation, the exhaust gas is quickly discharged. Suitable for supply to the intake side.

1 is an overall configuration diagram of an internal combustion engine according to a first embodiment. 3 is an explanatory diagram of a combustion region during operation of the internal combustion engine according to Embodiment 1. FIG. 1 is an explanatory diagram illustrating a configuration of an operation control device for an internal combustion engine according to a first embodiment. FIG. 3 is a flowchart illustrating a procedure of a start control method for the internal combustion engine according to the first embodiment. 3 is an overall configuration diagram of an internal combustion engine according to Embodiment 2. FIG. 7 is a flowchart illustrating a procedure of a start control method for an internal combustion engine according to a second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 3 In-cylinder injection valve 4 Intake valve 5 Port injection valve 6 Exhaust valve 10 Turbo (turbocharger)
10c Compressor 10t Turbine 11 Intake bypass valve 12 Exhaust bypass valve 13 EGR valve 20 Compressor upstream intake passage 20b Intake bypass passage 21 Compressor downstream intake passage 22 Intake port 23 Exhaust manifold (turbine upstream exhaust passage)
23b Exhaust bypass passage 24 Turbine downstream exhaust passage 30 Engine ECU
DESCRIPTION OF SYMBOLS 50 Operation control apparatus of internal combustion engine 51 Operation state determination part 52 Exhaust gas recirculation pressure control part 52 Operation state determination part 53 Exhaust gas recirculation operation part

Claims (6)

An internal combustion engine capable of switching between a homogeneous lean operation using supercharging together with a stratified operation according to operating conditions,
A supercharging means including a turbine driven by exhaust and a compressor connected to the turbine and pressurizing air;
Exhaust bypass means for flowing the exhaust of the internal combustion engine downstream of the turbine after bypassing the turbine;
Intake bypass means for supplying air to the internal combustion engine after bypassing the compressor;
An exhaust gas recirculation means for extracting the exhaust gas of the internal combustion engine from the downstream of the turbine and recirculating the exhaust gas to the intake side of the internal combustion engine,
When shifting from a homogeneous lean operation using supercharging to a stratified operation, air is supplied to the internal combustion engine after bypassing the compressor by at least the intake bypass means, and the internal combustion engine is supplied by the exhaust gas recirculation means. An internal combustion engine that recirculates exhaust gas.   2. The internal combustion engine according to claim 1, wherein when shifting from the homogeneous lean operation using supercharging to the stratified operation, the exhaust of the internal combustion engine is further caused to flow downstream of the turbine by the exhaust bypass means. . An internal combustion engine capable of switching between a homogeneous lean operation using supercharging together with a stratified operation according to operating conditions,
A supercharging means including a turbine driven by exhaust and a compressor connected to the turbine and pressurizing air;
Exhaust bypass means for flowing the exhaust of the internal combustion engine downstream of the turbine after bypassing the turbine;
Intake bypass means for supplying air to the internal combustion engine after bypassing the compressor;
Recirculation means for extracting the exhaust of the internal combustion engine from the upstream of the turbine and recirculating the exhaust of the internal combustion engine to the intake side of the internal combustion engine;
When shifting from homogeneous lean operation with supercharging to stratified operation, air is supplied to the internal combustion engine after the compressor is bypassed by the intake bypass means, and exhaust of the internal combustion engine is introduced into the turbine In this state, the exhaust gas from the internal combustion engine is recirculated by the exhaust gas recirculation means.   In the homogeneous lean operation that includes a port injection valve that injects fuel into the intake port of the internal combustion engine and an in-cylinder injection valve that injects fuel into the cylinder of the internal combustion engine, and uses supercharging together, the port injection The internal combustion engine according to any one of claims 1 to 3, wherein fuel is injected from a valve, and fuel is injected from the in-cylinder injection valve in stratified operation. A supercharging means that can switch between a homogeneous lean operation using supercharging and a stratified operation depending on operating conditions, and includes a turbine driven by exhaust and a compressor that is connected to the turbine and pressurizes air. And exhaust gas recirculation means for extracting the exhaust gas of the internal combustion engine from the downstream of the turbine and recirculating the exhaust gas to the intake side,
When the internal combustion engine transitions from the homogeneous combustion operation to the stratified operation, an exhaust gas recirculation pressure control unit that supplies air to the internal combustion engine after bypassing at least the compressor;
An exhaust gas recirculation operation unit for recirculating exhaust gas of the internal combustion engine by the exhaust gas recirculation means;
An operation control device for an internal combustion engine, comprising: A supercharging means that can switch between a homogeneous lean operation using supercharging and a stratified operation depending on operating conditions, and includes a turbine driven by exhaust and a compressor that is connected to the turbine and pressurizes air. And an exhaust gas recirculation means for extracting the exhaust gas from the internal combustion engine from the upstream side of the turbine and recirculating the exhaust gas to the intake side.
When the internal combustion engine shifts from the homogeneous combustion operation to the stratified operation, at least the compressor is bypassed and then the air is supplied to the internal combustion engine, and the exhaust gas recirculation pressure control is introduced into the turbine. And
An exhaust gas recirculation operation unit for recirculating exhaust gas of the internal combustion engine by the exhaust gas recirculation means;
An operation control device for an internal combustion engine, comprising:

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