JP2009264328A - Intake control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control a decrease in efficiency of filling a cylinder with fresh air due to mixture of EGR gas during inertia supercharging by an intake control valve. <P>SOLUTION: An intake control device includes: a tank opening/closing valve (224) for communicating between a tank (223) and an intake passage (204) when the valve is opened and for blocking the communication between the tank and the intake passage when the valve is closed; and a control unit (100) for controlling an EGR valve (242), the tank opening/closing valve, and the intake control valve, when the EGR gas is refluxed by opening the EGR valve, if the intake control valve (226) is controlled so as to start inertia supercharging, such that the tank opening/closing valve is switched from a closed state to an opened state at a delayed timing (T2) which is delayed by a prescribed delay time (DT) from a valve-closing start timing (T1) at which the EGR valve is switched from the opened state to the closed state and such that the inertia supercharging is started after the delayed timing. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technical field of an intake control device for an internal combustion engine capable of inertia supercharging such as impulse charge.

  As this type of intake control device, an intake control valve provided in an intake passage downstream of a surge tank has been proposed (see, for example, Patent Document 1). According to the intake control device disclosed in Patent Document 1 (hereinafter referred to as “conventional technology”), an inertia supercharging effect can be obtained by opening the intake control valve after the intake valve downstream of the intake port is opened. It is supposed to be possible.

  On the other hand, in Patent Document 2, for example, in an engine with a turbocharger, the operating region of the engine shifts from an exhaust gas recirculation (EGR) region in which exhaust gas is recirculated to the intake passage to a high load side by acceleration. In some cases, a technique for preventing the exhaust gas recirculation amount from becoming excessive by controlling the closing operation of the variable blades of the turbocharger to be delayed is proposed. Further, for example, Patent Document 3 proposes a technique for controlling an air flow control valve provided in an intake manifold for controlling a swirl flow in a cylinder of an engine with a delay correction corresponding to an intake delay. . Further, for example, in Patent Document 4, a sub tank is provided between a surge tank and an intake port via a communication portion provided with a control valve, so that the engine shifts from a high load state to a low load state and the control valve is opened. There has been proposed a technique for realizing an appropriate ignition timing by maintaining the opening of the EGR valve at a predetermined operation delay time and the opening before switching when switching to the closed state.

JP-A-5-187238 JP 2000-205055 A JP 2002-332884 A JP 2004-245062 A

  However, according to the conventional technique, when a part of the exhaust gas is recirculated to the intake passage as EGR gas, the surge tank provided in the middle of the intake passage is filled with the EGR gas. There is a technical problem that excessive EGR gas may be mixed into the cylinder during inertial supercharging by the intake control valve after gas introduction. Therefore, there is a possibility that the charging efficiency of new air (that is, fresh air) from the outside into the cylinder is lowered. As a result, the output torque of the internal combustion engine may be reduced.

  The present invention has been made in view of the above-described problems, for example, and is an internal combustion engine capable of suppressing a decrease in the efficiency of charging fresh air into a cylinder due to mixing of EGR gas during inertia supercharging by an intake control valve. It is an object to provide an intake control device.

  In order to solve the above problems, an intake control device for an internal combustion engine according to the present invention is provided with an intake passage communicating with the inside of a cylinder and an intake passage by being controlled in an open / close state according to a predetermined open / close control. An intake control valve capable of realizing inertial supercharging utilizing pulsation, and at least one opening, are arranged in parallel on the upstream side of the intake control valve so as to communicate with the intake passage via the opening A tank, an EGR passage that recirculates a part of the exhaust gas discharged from the cylinder as EGR gas from the exhaust side of the cylinder to the intake passage, and the EGR passage, the flow rate of the EGR gas being adjustable An intake control apparatus for an internal combustion engine comprising an EGR valve, wherein the tank and the intake passage are communicated when the valve is opened, and the communication between the tank and the intake passage is blocked when the valve is closed. When the intake control valve is controlled so that the inertia supercharging is started when the EGR gas is recirculated by opening the valve opening and closing valve and the EGR valve, the EGR valve The tank opening / closing valve changes from the closed state to the open state at a timing delayed by a predetermined delay time from the valve closing start timing from the valve opening state to the valve closing state. Control means for controlling the EGR valve, the tank on-off valve, and the intake control valve so as to start inertia supercharging.

  In the present invention, the intake control valve is provided in the intake passage communicating with the inside of the cylinder of the internal combustion engine. The intake control valve can adjust the intake amount as the amount of intake air, for example, in accordance with the open / closed state that can be controlled in a binary, stepwise or continuous manner, for example, in addition to the valve body or the valve body. It is a means that can take various forms such as a valve operating mechanism or a valve operating apparatus that appropriately includes a drive device that drives the valve body, etc., and is suitable when the internal combustion engine is equipped with a so-called intake throttle valve such as a throttle valve. As one form, it is installed downstream of the intake throttle valve. The installation mode of the intake control valve may take various forms depending on, for example, the physical configuration of the intake passage. That is, the intake passage may be branched to each cylinder on the downstream side of the intake control valve (that is, a mode similar to a so-called one-valve intake system), or each cylinder provided with an intake control valve. Corresponding communication pipes or intake branch pipes (including the like) may be provided.

  The internal combustion engine includes a tank such as a surge tank, for example, which is provided so as to communicate with the intake passage through the opening. Here, the “parallel arrangement” is a concept comprehensively arranged in a positional relationship where the flow of the intake air in the intake passage is not blocked even when communication through at least the opening is blocked. As a preferred form, the opening and the intake passage are connected by a predetermined pipe branching from the intake passage (preferably, the pipe diameter may be substantially the same as the intake passage). This includes the configuration and the like.

  Here, the intake control valve according to the present invention, whether single or plural, is configured to be able to generate intake air pulsation by controlling its open / closed state according to predetermined open / close control, and pulsates the tank. By using it as means for inverting the phase of the wave, it is possible to realize inertia supercharging (or also called pulse supercharging or impulse charge) using the pulsation of intake air. Here, the “predetermined opening / closing control” is, for example, the opening / closing timing, opening period or opening degree of the intake control valve (that is, the degree of opening of the intake control valve) to achieve this kind of inertia supercharging. For example, a valve closing timing of an intake valve (that is, a valve for controlling the communication state between the combustion chamber and the intake passage as a preferred embodiment), and the like. This is intended to include control to synchronize the time when the peak of the pulsation wave (positive pressure wave) of intake reaches the intake valve (not necessarily representing only coincidence). More specifically, the open / close control is, for example, that the intake control valve is opened after an appropriate time elapse (may be defined as an angle concept by a crank angle or the like) after the intake valve is opened (that is, the intake control). Combustion chamber of each cylinder that generates a positive pressure wave by opening the valve in a state where the downstream side of the valve is negative pressure and the upstream side of the intake control valve is at or above atmospheric pressure, etc. When a negative pressure wave is reflected in the vicinity of the entrance and this negative pressure wave is reflected at the open end of the tank again at the open end, so-called secondary positive pressure wave is used, for example, when natural intake is performed (a suitable one) As a form, the intake air can be basically taken into the cylinder as a pulsation wave regardless of the presence or absence of the intake control valve, but the pulsation caused by the opening / closing control applied to the intake control valve is a suitable form. The pulsation of Also meant to comprise control, etc. to be made to incorporate a strong pulsation in a) compared to the cylinder in the intake stroke a large amount of intake air.

  An intake control device for an internal combustion engine according to the present invention is provided, for example, in a pipe line connecting the above-described opening and an intake passage (of course, it can be established even if such a pipe does not exist), and a tank is opened when the valve is opened. And a tank open / close valve that can control the open / close state of the tank and the intake passage in a binary, stepwise, or continuously variable manner.

  In the present invention, in particular, control means that can be configured as various processing units such as an ECU (Electronic Control Unit), various controllers or various computer systems such as a microcomputer device, etc., by opening the EGR valve. When the EGR gas is recirculated, when the intake control valve is controlled so that inertia supercharging (that is, pulse supercharging) using intake air pulsation is started, the EGR valve is At a timing delayed by a predetermined delay time from the valve closing start timing toward the valve closing state, the tank opening / closing valve is changed from the valve closing state to the valve opening state, and after the delay timing, inertia supercharging by the intake control valve is performed. The EGR valve, the tank opening / closing valve and the intake control valve are controlled so as to be started. In other words, the control means starts from the valve closing start timing of the EGR valve when performing pulse supercharging during acceleration of an internal combustion engine that is in a low rotation and light load state with EGR gas being introduced into the intake passage. After a predetermined delay time, the opening / closing timings of the EGR valve, the tank opening / closing valve, and the intake control valve are controlled so that the tank opening / closing valve is opened and the pulse supercharging is started. In other words, the control means is configured to return the EGR gas to the intake passage by opening the EGR valve, and to the period delayed by a predetermined delay time from the EGR valve closing start timing. Control the EGR valve, tank open / close valve and intake control valve so that the tank open / close valve is closed and the tank open / close valve is opened after the delayed timing and the pulse supercharging by the intake control valve is started. To do.

  Therefore, it is possible to suppress or prevent EGR gas from entering the tank from the intake passage through the opening and filling the tank with EGR gas, and a large amount of EGR in the cylinder by pulse supercharging by the intake control valve. The inflow of gas can be suppressed or prevented. Therefore, it is possible to suppress or prevent a decrease in the efficiency of charging fresh air into the cylinder due to the mixing of EGR gas. As a result, it is possible to suppress or prevent the output torque of the internal combustion engine from decreasing. Furthermore, it is possible to prevent the exhaust emission from deteriorating due to the occurrence of smoke due to the deterioration of the combustion state of the internal combustion engine with the inflow of a large amount of EGR gas.

  In one aspect of the intake control device for an internal combustion engine according to the present invention, the control means is configured so that the timing at which the tank on-off valve is opened is after the timing at which the EGR valve is closed. The EGR valve and the tank opening / closing valve are controlled.

  According to this aspect, since the tank opening / closing valve is opened after the EGR valve is closed, it is possible to more reliably suppress or prevent the tank from being filled with EGR gas.

  In another aspect of the intake control device for an internal combustion engine according to the present invention, the control means is configured so that the timing at which the inertia supercharging is started is later than the timing at which the tank on-off valve is opened. The tank opening / closing valve and the intake control valve are controlled.

  According to this aspect, since the inertial supercharging by the intake control valve is performed after the tank opening / closing valve is opened, the generation of smoke can be further reliably suppressed, and the inertial supercharging can be suitably performed. it can.

  In another aspect of the intake control apparatus for an internal combustion engine according to the present invention, the predetermined delay time is defined to be shorter as the rotational speed of the internal combustion engine is larger.

  According to this aspect, it is possible to perform inertia supercharging by the intake control valve at an early stage while suppressing the generation of smoke according to the rotational speed of the internal combustion engine. Therefore, the acceleration performance of the internal combustion engine can be improved.

  In another aspect of the intake control apparatus for an internal combustion engine according to the present invention, the predetermined delay time is determined by the flow rate of the EGR gas and the amount of air sucked into the internal combustion engine when the EGR gas is recirculated. The smaller the EGR rate, which is the ratio of the flow rate of the EGR gas to the total amount with respect to the inhaled amount, is defined to be shorter.

  According to this aspect, it is possible to perform inertia supercharging by the intake control valve at an early stage while suppressing the generation of smoke according to the EGR rate. Therefore, the acceleration performance of the internal combustion engine can be improved.

  The operation and other advantages of the present invention will become apparent from the best mode for carrying out the invention described below.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, the configuration of the engine system according to the present embodiment will be described with reference to FIG.

  FIG. 1 is a block diagram illustrating a configuration of an engine system including an intake air control device according to the present embodiment.

  In FIG. 1, an engine system 10 is mounted on a vehicle (not shown) and includes an ECU 100 and an engine 200.

  The ECU 100 is an electronic control unit that includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and is configured to be able to control the entire operation of the engine 200. It is an example of the "control means" concerning.

  The engine 200 is an in-line four-cylinder diesel engine that is an example of an “internal combustion engine” according to the present invention that uses light oil as fuel. The engine 200 has a configuration in which four cylinders 202 are arranged in parallel on a cylinder block 201. In each cylinder 202, in the compression stroke, a mixture of fuel and intake air directly injected into the cylinder during the compression stroke or the intake stroke is compressed, and the force generated when the cylinder spontaneously ignites is not shown. It is configured to be converted into a rotational motion of the crankshaft via a piston and a connecting rod. The rotation of the crankshaft is transmitted to drive wheels of a vehicle on which the engine system 10 is mounted, and the vehicle can travel.

  In FIG. 1, the intake air, which is air guided from the outside, is guided to an intake pipe 204 which is an example of an “intake passage” according to the present invention. The intake pipe 204 is provided with a throttle valve 205 capable of adjusting the amount of intake air guided to the intake pipe 204. The throttle valve 205 is a rotary valve that is configured to be rotatable by a driving force supplied from a throttle valve motor (not shown) that is electrically connected to the ECU 100 and controlled by the ECU 100 at the upper level. The rotational position is continuously controlled from a fully closed position where the upstream and downstream portions of the intake pipe 204 at the boundary are substantially blocked to a fully open position where the intake pipe 204 communicates almost entirely. As described above, in the engine 200, the throttle valve 205 and the throttle valve motor constitute a kind of electronically controlled throttle device.

  Engine 200 is a diesel engine, and its output is controlled through injection amount increase / decrease control, unlike air-fuel ratio control (fuel injection control based on intake air amount) in an engine using gasoline or the like as fuel. The Therefore, the amount of intake air sucked through the throttle valve 205 is not substantially limited at least on the upper limit side, and the throttle valve 205 is basically in the most part of the operation period of the engine 200. It is controlled to the fully open position.

  The intake pipe 204 is connected to the communication pipe 206 on the downstream side of the throttle valve 205 and is configured to communicate with the communication pipe 206 therein. The communication pipe 206 communicates with each intake port (not shown) of each cylinder 202, and the intake air guided to the intake pipe 204 is guided to the intake port corresponding to each cylinder via the communication pipe 206. It is configured to be written. The intake port is configured to communicate with the inside of the cylinder 202. The intake pipe 204 and the communication pipe 206 constitute an example of the “intake passage” according to the present invention.

  The communication state between the intake port and the cylinder 202 is controlled by an intake valve provided in each intake port. The intake valve is fixed to the intake camshaft that rotates in conjunction with the crankshaft, and its open / close characteristics are defined according to the cam profile of the intake cam, whose section perpendicular to the extension direction of the intake camshaft is elliptical. Thus, the intake port and the cylinder 202 can communicate with each other when the valve is opened. As described above, in the engine 200, the communication pipe 206 is concentrated on the upstream side of the portion corresponding to each cylinder 202 (more specifically, the intake port), so that a so-called single valve type intake manifoldless intake system is realized. Yes.

  A fuel injection valve as a part of an in-cylinder injector is exposed inside the cylinder 202, and is configured so that light oil as fuel can be directly injected into a high-temperature and high-pressure cylinder.

  The air-fuel mixture formed in the cylinder 202 is self-ignited and burned in the compression stroke, and is opened as an exhaust valve that opens and closes in conjunction with the opening and closing of the intake valve as a burned gas or a partially unburned air-fuel mixture. At the time of valve operation, exhaust gas is guided to the exhaust manifold 213 through an exhaust port (not shown).

  The engine 200 includes a turbocharger 218. The darbo supercharger 218 includes a turbine 218a and a compressor 218b. The turbine 218 a is disposed in the exhaust pipe 214, and the compressor 218 b is disposed in the intake passage 204. The turbocharger 218 operates the compressor 218b by the rotational energy of the turbine 218a through which the exhaust gas passes. The compressor 218b is configured to be able to pump and supply the intake air sucked into the intake pipe 204 from the outside via the air cleaner 219 to the downstream side by the pressure accompanying the rotation. The so-called supercharging is realized by the pumping effect.

  In the intake pipe 204, an intercooler 221 is installed on the downstream side of the compressor 218b and the upstream side of the throttle valve 205. The intercooler 221 has a heat exchange wall inside thereof, and when the supercharged intake air passes (similarly in a low rotation region where the compressor 218b does not act substantially), The intake air can be cooled by heat exchange via the heat exchange wall. The engine 200 can increase the density of the intake air by the cooling by the intercooler 221, so that the supercharging via the compressor 218b can be performed more efficiently.

  The engine 200 is provided with an EGR passage 240 that communicates the exhaust manifold 213 and the intake pipe 204 (more specifically, the downstream side of the throttle valve 205 in the intake pipe 204). Exhaust gas guided from the exhaust manifold 213 to the EGR passage 240 is recirculated to the intake pipe 204 as EGR gas. An EGR cooler 241 is installed in the middle of the EGR passage 240. The EGR cooler 241 is a cooling device that cools the EGR gas. An EGR valve 242 is provided downstream of the EGR cooler 241 in the EGR passage 240. The EGR valve 242 is a valve mechanism including a valve body that can be opened and closed and a drive device that drives the valve body. The valve body of the EGR valve 242 is configured so that the open / close state is continuously changed by the driving device, and the flow rate of the EGR gas flowing through the EGR passage 240 according to the open / close state (that is, the EGR gas flow rate). It is possible to control. The drive device of the EGR valve 242 is electrically connected to the ECU 100, and the open / close state of the valve body of the EGR valve 242 is controlled by the ECU 100 to the upper level. That is, the opening degree of the valve body of the EGR valve 242 (that is, the EGR valve opening degree) is configured to be controlled higher by the ECU 100.

  On the downstream side of the throttle valve 205 in the intake pipe 204, a branch pipe 222 having the same diameter as that of the intake pipe 204 is branched while maintaining communication with the intake pipe 204. The inside of the branch pipe 222 is further connected to a surge tank 223 that communicates with the branch pipe 222 through a communication hole (that is, an example of the “opening” according to the present invention). That is, the surge tank 223 is configured to communicate with the intake pipe 204 through the communication hole and the branch pipe 222.

  The surge tank 223 suppresses irregular pulsation of the intake air supplied while appropriately receiving the supercharging action of the turbocharger 218 described above, and stably intake air on the downstream side (that is, the cylinder 202 side). And a storage means configured to be able to invert the phase of the negative pressure wave at the time of execution of impulse charge described later. However, since the intake air is basically supplied to the cylinder 202 while pulsating to a greater or lesser extent, the intake air passing through the surge tank 223 is also a kind of pulsating wave.

  On the other hand, the branch pipe 222 is provided with a surge tank valve 224 capable of controlling the communication state between the surge tank 223 and the intake pipe 204. The surge tank valve 224 is an example of the “tank opening / closing valve” according to the present invention, and its opening / closing state is controlled according to the driving force supplied from the actuator 225. The actuator 225 is electrically connected to the ECU 100, and the driving state is controlled by the ECU 100. That is, the open / close state of the surge tank valve 224 is controlled by the ECU 100.

  The surge tank valve 224 is configured so that the surge tank valve opening degree that regulates the open / closed state is continuously variable, but here, for the sake of simplicity of explanation, the surge tank valve opening degree is set to the branch pipe. Between a fully closed opening that blocks communication between the intake pipe 204 and the surge tank 223 via 222 and a fully opened opening that allows the intake pipe 204 and surge tank 223 to communicate through the branch pipe 222 to the maximum extent. It shall be switched in binary.

  A single impulse valve 226 is provided in a section 204 a of the intake pipe 204 between the branch position with the branch pipe 222 and the connection position with the communication pipe 206. The impulse valve 226 is an example of the “intake control valve” according to the present invention, and the opening degree defined by the position of the valve body is a fully closed opening degree that blocks communication between the intake pipe 204 and the communication pipe 206. This is an electromagnetic control valve configured to continuously change between a fully open opening degree that allows the intake pipe 204 and the communication pipe 206 to communicate almost entirely. The impulse valve 226 is configured such that its opening degree is controlled by the driving force supplied from the actuator 227. The actuator 227 is electrically connected to the ECU 100, and the driving state of the actuator 227 is controlled by the ECU 100. That is, the opening degree of the impulse valve 226 is controlled by the ECU 100.

  A DPNR (Diesel Particulate NOx Reduction system) 228 is installed in the exhaust pipe 214. The DPNR 228 is an exhaust purification device and has a DPF 228a. More specifically, the DPNR 228 includes a CCO (oxidation catalyst) (not shown), a DPF 228a, and an NSR catalyst (not shown) arranged in parallel in the exhaust flow direction.

  CCO is a catalyst that is configured to carry a noble metal such as platinum on a porous basic carrier such as alumina, and is capable of oxidizing CO, HC (mainly SOF), NO and the like in exhaust gas.

  The DPF 228a is a filter configured to be able to capture PM (Particulate Matter: particulate matter) in the exhaust gas. The DPF 228a has a structure in which a filter made of a ceramic carrier such as cordierite or SiC is accommodated in a metal casing. This filter has a plurality of exhaust passages extending in the direction of exhaust flow and having a cross section perpendicular to the direction of exhaust flow forming a honeycomb shape. The exhaust passages are alternately sealed so that one of the inlet side and the outlet side of the exhaust is not adjacent to each other, and the DPF 228a has a so-called ceramic wall flow type filter structure.

  The NSR catalyst is a NOx occlusion reduction catalyst in which a NOx occlusion material such as alkali metal or alkaline earth metal and a noble metal are supported on a porous carrier such as alumina. The NSR catalyst oxidizes NO in exhaust gas to NOx on a noble metal in a lean atmosphere, and the NOx occlusion material, which is a basic substance, neutralizes and reacts with NOx to form nitrates and nitrites to occlude NOx. In the fuel-rich atmosphere, the stored nitrates and nitrites are decomposed and NOx is released, and it reacts with reducing agents such as HC and CO by the catalytic action of precious metals. The structure is purified to N2.

  The required load of the engine 200 is determined according to an accelerator opening degree Ta which is an operation amount (that is, an operation amount by a driver) of an unillustrated accelerator pedal. The accelerator opening degree Ta is detected by the accelerator opening degree sensor 11 and is grasped at a constant or indefinite period by the ECU 100 electrically connected to the accelerator opening degree sensor 11. In general, the smaller the accelerator opening, the smaller the required load, and the larger the accelerator opening, the larger the required load. Since the magnitude of the required load correlates with the magnitude of the required output, in the engine system 10, the engine required output changes according to the accelerator opening degree Ta.

  In the engine system 10 according to the present embodiment, the engine 200 as a diesel engine is employed as an example of the “internal combustion engine” according to the present invention. However, the internal combustion engine according to the present invention refers only to a diesel engine. Of course, a gasoline engine, an engine using alcohol mixed fuel, or the like may be used. Further, the engine 200 according to the present embodiment has a so-called single valve type intake manifold intake system in which the communication pipe 206 branches to each cylinder on the downstream side of the impulse valve 226. However, the impulse valve 226 may not be configured to be shared and shared by the respective cylinders 202 as described above, and a plurality of impulse valves 226 may be provided for each cylinder 202 in a portion corresponding to each cylinder in the communication pipe 206.

  Here, the impulse charge in the engine system according to the present embodiment will be described with reference to FIG.

  In FIG. 1, in the engine system 10, the impulse charge is executed by the ECU 100 performing predetermined opening / closing control on the impulse valve 226. Here, the impulse charge refers to inertial supercharging utilizing intake air pulsation caused by opening and closing of the impulse valve 226. More specifically, when one cylinder 202 reaches the intake stroke with the impulse valve 226 closed, the intake valve of the cylinder 202 is opened and the piston of the cylinder 202 starts to descend. At this time, since the impulse valve 226 is closed, the internal pressure of the communication pipe 206 becomes negative, and the pressure difference from the internal pressure of the intake pipe 204 maintained at atmospheric pressure or higher due to supercharging is increased. To do.

  In such a state, when the impulse valve 226 is opened (that is, opened during a valve opening period after the intake valve opening timing), the intake pipe 204 and the corresponding cylinder 202 (that is, the intake stroke at that time). The inside of a cylinder) communicates with the interior of the cylinder 202, and the intake air flows into the combustion chamber inside the cylinder 202 at once as the intake air via the impulse valve 226.

  On the other hand, the communication pipe 206 is a so-called open end at the communication part with the combustion chamber, and the positive pressure wave caused by the inflow of the intake air into the combustion chamber is reflected by the combustion chamber, so that the phase is inverted. It becomes a pressure wave. The negative pressure wave reaches the surge tank 223 via the communication pipe 206, the impulse valve 226, and the branch pipe 222 in this order, and is reflected back to the combustion chamber as a positive pressure wave whose phase is inverted by reflection at the open end. To reach. When the peak of this positive pressure wave reaches the combustion chamber (or the intake valve) (not necessarily limited to that point in time, it is constant including that point as long as the charging efficiency of the intake can be improved to some extent) (It may be an indefinite period.) The valve opening timing of the impulse valve 226 is controlled so that the positive pressure wave reaches the combustion chamber by closing the intake valve or when the intake valve closes. As a result (this embodiment is adopted here), the pressure in the combustion chamber rises, and the intake charging efficiency is improved. Impulse charging using the impulse valve 226 is executed in this way.

  In the engine system 10 according to the present embodiment, in particular, when impulse charging is executed during acceleration of the engine 200 in a low rotation and light load state with the EGR gas being introduced into the intake pipe 202, the EGR valve Each of 242, surge tank valve 224 and impulse valve 226 is controlled by ECU 100 as follows.

  FIG. 2 shows the accelerator opening and EGR valve opening when the engine is accelerated at low speed and light load with EGR gas being introduced into the intake pipe in this embodiment. 5 is a timing chart showing changes over time in the degree, the surge tank valve opening degree, and the impulse charge execution flag.

  1 and 2, in a state where a part of the exhaust gas is introduced as EGR gas from the EGR passage 240 into the intake pipe 204 (that is, the EGR valve 242 is opened), the accelerator opening degree Ta is predetermined at the timing T1. The ECU 100 controls the EGR valve 242 so that the EGR valve 242 moves from the open state to the closed state almost or completely simultaneously with the timing T1 (in other words, the EGR valve is opened). The degree is controlled from the open state to the closed state). Here, the accelerator opening degree Ta is an index value corresponding to the required load of the engine 200, and the predetermined reference value is a value that can make a determination that inertia supercharging is necessary in terms of the required load. is there. In other words, in the low load region below the predetermined reference value, since it is not necessary to increase the intake charge amount from the beginning, it is not necessary to execute the impulse charge. Therefore, the ECU 100 sets the impulse charge execution flag that defines whether or not to execute the impulse charge to an off state (OFF) at least before the timing T1. Further, in a state where the EGR gas is introduced into the intake pipe 204 (in other words, before the timing T1 on the time axis in FIG. 2), the ECU 100 sets the surge tank valve so that the surge tank valve 224 is closed. 224 is controlled (in other words, the surge tank valve opening is controlled so as to be closed). Thereby, it is possible to prevent the EGR gas being refluxed from flowing into the surge tank 223 when the EGR valve 242 is opened. As will be described later, particularly in the present embodiment, the ECU 100 opens the surge tank valve 224 and turns on the impulse charge execution flag at the timing T2 after the EGR valve 242 is closed. Set to (ON).

  Particularly in the present embodiment, when the ECU 100 executes the impulse charge in response to the accelerator opening degree Ta increasing from the predetermined reference value at the timing T1, the timing delayed by the predetermined delay time DT from the timing T1. At T2, the EGR valve 242, the surge tank valve 224, and the impulse valve 226 are controlled so that the surge tank valve 224 is changed from the closed state to the opened state, and the execution of the impulse charge is started after the timing T2. . In other words, the ECU 100 makes the EGR valve 224 open to return the EGR gas to the intake pipe 204, and the valve closing start timing of the EGR valve 224 (in the present embodiment, almost or completely coincides with the timing T1). The surge tank valve 224 is closed during a period from the timing to the timing T2 delayed by a predetermined delay time DT, and the surge tank valve 242 is opened after the timing T2 and the impulse charge execution flag is set. Set to on.

  Therefore, EGR gas remaining in the intake pipe 204 after the EGR valve 242 is closed in accordance with the timing T1 enters the surge tank 223 from the intake pipe 204 via the branch pipe 222 and its communication hole, and the surge tank 223 It is possible to suppress the inside from being filled with EGR gas, and it is possible to prevent a large amount of EGR gas from flowing into the cylinder 202 due to the impulse charge by the impulse valve 226. Accordingly, it is possible to suppress a decrease in the efficiency of charging fresh air into the cylinder 202 due to the mixing of EGR gas. As a result, it can suppress that the output torque of the engine 200 falls. Further, it is possible to prevent smoke from being generated and exhaust emission from being deteriorated due to deterioration of the combustion state in the cylinder 202 due to inflow of a large amount of EGR gas. Therefore, it is possible to avoid a situation where the DPF 228a in the DPNR 228 is clogged with a large amount of PM (particulate matter) in the exhaust gas.

  It should be noted that the predetermined delay time DT may be defined such that it decreases as the rotational speed of the engine 200 increases. In this case, the impulse charge can be executed at an early stage while suppressing the generation of smoke according to the rotational speed of the engine 200. Therefore, the acceleration performance of engine 200 can be improved. Alternatively, the predetermined delay time DT is based on the EGR rate (that is, the total amount of the EGR gas flow rate and the air intake amount) in a state where the EGR gas is recirculated (in other words, a period in which the EGR valve is open). The ratio of the flow rate of the EGR gas, in other words, the CO2 concentration of the intake air) may be defined to be shorter. In this case, according to the EGR rate, impulse charge can be executed early while suppressing the occurrence of smoke.

  The present invention is not limited to the above-described embodiments, and can be changed as appropriate without departing from the spirit or concept of the invention that can be read from the claims and the entire specification. The control device is also included in the technical scope of the present invention.

It is a block diagram which shows the structure of the engine system provided with the intake control device which concerns on this embodiment. In this embodiment, the accelerator opening, the EGR valve opening, and the surge tank when the impulse charge is executed at the time of acceleration of the engine that is in the low rotation and light load state with the EGR gas being introduced into the intake pipe. It is a timing chart which shows a time-dependent change of a valve opening degree and an impulse charge execution flag.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... ECU, 200 ... Engine, 202 ... Cylinder, 204 ... Intake pipe, 206 ... Communication pipe, 222 ... Branch pipe, 223 ... Surge tank, 224 ... Surge tank valve, 225 ... Actuator, 226 ... Impulse valve, 227 ... Actuator 228 ... DPNR, 228a ... DPF, 240 ... EGR passage, 241 ... EGR cooler, 242 ... EGR valve

Claims (5)

An intake passage that communicates with the inside of the cylinder, an intake control valve that is installed in the intake passage and that is capable of realizing inertial supercharging utilizing intake air pulsation by controlling the open / close state according to predetermined open / close control, and at least one A tank that has an opening, and is arranged in parallel so as to communicate with the intake passage through the opening on the upstream side of the intake control valve; and a part of the exhaust gas discharged from the cylinder as EGR gas An intake air control apparatus for an internal combustion engine, comprising: an EGR passage that recirculates from an exhaust side of a cylinder to the intake passage; and an EGR valve that is provided in the EGR passage and is capable of adjusting a flow rate of the EGR gas,
A tank opening / closing valve that allows the tank and the intake passage to communicate with each other when the valve is opened, and shuts off the communication between the tank and the intake passage when the valve is closed;
When the intake control valve is controlled so that the inertia supercharging is started when the EGR gas is recirculated by opening the EGR valve, the EGR valve is opened. The tank opening / closing valve is changed from the closed state to the opened state at a timing delayed by a predetermined delay time from the valve closing start timing toward the valve closing state, and the inertia supercharging is started after the delayed timing. An intake air control apparatus for an internal combustion engine, comprising: a control means for controlling the EGR valve, the tank opening / closing valve, and the intake control valve.   The control means controls the EGR valve and the tank opening / closing valve so that the timing at which the tank opening / closing valve is opened is after the timing at which the EGR valve is closed. An intake control device for an internal combustion engine according to claim 1.   The control means controls the tank on / off valve and the intake control valve so that the timing at which the inertia supercharging is started is after the timing at which the tank on / off valve is opened. An intake control device for an internal combustion engine according to claim 1.   The intake control apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein the predetermined delay time is defined to be shorter as the rotational speed of the internal combustion engine is larger.   The predetermined delay time is a ratio of the flow rate of the EGR gas to the total amount of the flow rate of the EGR gas and the intake amount of air sucked into the internal combustion engine in the state where the EGR gas is recirculated. The intake control apparatus for an internal combustion engine according to any one of claims 1 to 4, wherein the intake air control apparatus is defined so as to be shorter as a certain EGR rate is smaller.

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