JP2006266159A - Exhaust recirculation gas introduction controller of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust recirculation gas introduction controller of an engine capable of easily providing the stratified state of an EGR gas and a suction gas despite the fact that its structure is rather simple. <P>SOLUTION: This controller comprises an intake air control valve 126 installed in an intake air passage 120 on the upstream side of an intake valve 107 and openable according to the opening/closing timings of the intake valve 107, an exhaust gas recirculation gas control valve 142 installed in an exhaust recirculation gas passage 141 opening to the intake gas passage 120 between the intake valve 107 and the intake control valve 126, an engine operating area determination part 200 determining whether the engine 100 is in an exhaust recirculation gas introduction area or not, and an opening/closing operation timing control means which, when the engine is determined to be in an exhaust recirculation gas introduction area by the engine operation area determination means, controllably differentiate the opening/closing operation timings of the intake control valve 126 and the exhaust recirculation gas control valve 142 from each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exhaust gas recirculation gas introduction control device for an engine, and in particular, an exhaust air recirculation gas (hereinafter referred to as EGR gas) is used to separately generate an intake air layer and an EGR gas layer in a combustion chamber. The present invention relates to an exhaust gas recirculation gas introduction control apparatus suitable for EGR stratified combustion.

  In general, in an internal combustion engine (in-cylinder direct injection engine or diesel engine) that directly injects fuel into a cylinder (combustion chamber), the air-fuel mixture is stratified in order to reduce the fuel consumption rate in a partial load range. There is known a method of reducing the pumping loss by ensuring the combustibility and making the air excessive with respect to the fuel. Also, an EGR stratified combustion engine has been proposed that uses EGR gas to stratify intake air and EGR gas in order to reduce nitrogen oxides (hereinafter referred to as NOx) and smoke that are likely to occur in such a combustion mode. Yes.

  As such an EGR stratified combustion engine, for example, the one described in Patent Document 1 is known. The mechanism disclosed in Patent Document 1 includes a mechanism that directly injects fuel into a combustion chamber, a mechanism that recirculates exhaust gas after combustion into the combustion chamber, and a mechanism that closes a part of the intake passage to generate a tumble. An internal combustion engine including: a first section through which a gas mainly containing intake air passes; a second section through which a gas mainly containing EGR gas passes; and a third section closed. It is divided into sections. Then, with the intake control valve having a notch portion over a rotation angle range of 90 degrees, the second compartment and the third compartment are controlled to open and close, and the EGR is placed in the second compartment with the intake control valve closed. By filling the gas and opening the intake control valve in the intake stroke of the engine, the EGR gas and the intake air in the second compartment flow in as a tumble in the same direction, so that the EGR gas and the intake air A stratified state is obtained.

JP 2004-257305 A

  By the way, in the structure described in Patent Document 1, in order to obtain a stratified state of EGR gas and intake air, the intake passage is divided into a plurality of sections, and these sections are opened and closed with an intake control valve having a notch. There is a problem that the structure must be complicated because it is controlled.

  An object of the present invention is to provide an exhaust gas recirculation gas introduction control device for an engine which can easily obtain a stratified state of EGR gas and intake air while having a relatively simple structure.

  An exhaust gas recirculation gas introduction control device for an engine that achieves the above object is provided in an intake passage upstream of an intake valve and can be opened and closed in accordance with the opening and closing timing of the intake valve, An exhaust gas recirculation gas control valve provided in an exhaust gas recirculation gas passage that opens in an intake air passage between the intake valve and the intake air control valve, and an engine operation region determination that determines whether or not the engine is in an exhaust gas recirculation gas introduction region And an open / close operation timing for controlling the intake control valve and the exhaust recirculation gas control valve differently when the engine is determined to be in the exhaust recirculation gas introduction region by the engine operating region determination means And a control means.

  Here, when the engine is a gasoline engine, the opening / closing operation timing control means preferably performs control so that the intake control valve is opened after the exhaust recirculation gas control valve is closed.

  When the downstream side of the intake control valve of the intake passage is constituted by a helical intake port and a tangential intake port, it is preferable that the exhaust gas recirculation gas passage is opened to the helical intake port.

  When the engine is a diesel engine having a cavity at the top of the piston, it is preferable that the opening / closing operation timing control means performs control so as to open the exhaust gas recirculation gas control valve after closing the intake control valve.

  And when the downstream of the said intake control valve of the said intake passage is comprised by the helical intake port and the tangential intake port, it is preferable that the said exhaust gas recirculation gas passage is opened to this tangential intake port.

  According to the exhaust recirculation gas introduction control device for an engine according to one aspect of the present invention, when the engine operating region determination unit determines that the engine is in the exhaust recirculation gas introduction region, the opening / closing operation timing control unit controls the intake valve. The opening and closing operation timings of the intake control valve that can be opened and closed in accordance with the opening and closing timing of the exhaust gas and the exhaust gas recirculation gas control valve provided in the exhaust gas recirculation gas passage that opens in the intake passage between the intake valve and the intake control valve are made different. Controlled. Therefore, since the intake air and the exhaust gas recirculation gas are introduced into the cylinder at different times, a stratified state of the EGR gas and the intake air can be easily obtained.

  Here, the engine is a gasoline engine, and the opening / closing operation timing control means controls the opening of the intake control valve after closing the exhaust gas recirculation gas control valve. Since the EGR gas is introduced into the intake air and the intake air is introduced with a delay during the turning, a stratified state of the outer EGR gas layer and the inner intake air layer can be obtained.

  And, the downstream of the intake control valve in the intake passage is constituted by a helical intake port and a tangential intake port, and the exhaust gas recirculation gas passage is opened to the helical intake port, the intake stroke described above Since the initial EGR gas is introduced through the helical intake port, the swirl of the EGR gas can be increased even when the intake valve lift amount is small at the initial stage of the intake stroke, and a better outer EGR gas layer and A stratified state with the inner intake air layer can be obtained.

  Further, according to a mode in which the engine is a diesel engine having a cavity at the top of the piston, the opening / closing operation timing control means controls to open the exhaust gas recirculation gas control valve after closing the intake control valve. The intake air is introduced at the beginning of the intake stroke, and the EGR gas is introduced after the state in which the intake air is maintained in the cavity due to the flow in the cylinder. Although this EGR gas is inside in the cylinder, it circulates outside the intake air in the cavity, and a stratified state of the outer EGR gas layer and the inner intake air layer can be obtained in the cavity where fuel injection is directed. it can.

  And, the downstream of the intake control valve in the intake passage is constituted by a helical intake port and a tangential intake port, and the exhaust gas recirculation gas passage is opened to the tangential intake port. Since the introduction of EGR gas after the state in which the intake air is maintained in the cavity due to the flow is performed through the tangential intake port, a stronger swirl of EGR gas can be obtained in the later stage of the intake stroke, and fuel injection can be performed. A better stratified state of the outer EGR gas layer and the inner intake air layer can be obtained in the directed cavity.

  An embodiment in which an engine exhaust gas recirculation gas introduction control device according to the present invention is applied to a gasoline engine will be described in detail with reference to FIG. It should be noted that the present invention is not limited to such an embodiment, but can be modified or modified within the concept of the present invention described in the claims, and thus other modifications belonging to the spirit of the present invention. Of course, it can be applied to any technique.

  The concept of the engine system in this embodiment is shown in FIG. The engine 100 in this embodiment is of a type in which gasoline, which is fuel, is directly injected into the combustion chamber 102 from the fuel injection valve 101 and ignited by ignition of the spark plug 103, but alcohol or the like is used as fuel. Is also possible.

  A cylinder head 106 formed with an intake port 104 and an exhaust port 105 respectively facing the combustion chamber 102 includes an intake valve 107 that opens and closes the intake port 104 and an exhaust valve 108 (not shown) that opens and closes the exhaust port 105. Is incorporated.

  At the upstream end side of the intake pipe 121 that is connected to the cylinder head 106 so as to communicate with the intake port 104 and defines the intake passage 120 together with the intake port 104, dust and the like contained in the atmosphere are removed to remove the intake passage 120. An air cleaner 122 is provided for guiding the air. A throttle valve 124 whose opening is adjusted by a throttle actuator 123 based on the amount of depression of an accelerator pedal (not shown) operated by a driver is incorporated in a portion of the intake pipe 121 located on the downstream side of the air cleaner 122. ing. In this embodiment, the depression operation of the accelerator pedal and the opening / closing operation of the throttle valve 124 can be separated and electrically controlled. However, the accelerator pedal and the throttle valve 124 are mechanically connected. May be. Further, an intake control valve 126 that opens and closes the intake passage 120 by an actuator 125 at a predetermined timing according to the opening and closing timing of the intake valve 107 is incorporated in a portion of the intake pipe 121 located downstream of the throttle valve 124. It is. When engine 100 has a plurality of intake ports 104 and intake valves 107 per cylinder, as described later, intake control valves 126 are provided independently for each intake port 104, and each intake port 104 is opened and closed individually. However, the intake control valve 126 may be opened and closed in units of individual cylinders. The intake control valve 126 and its actuator 125 have extremely high control response so that the intake control valve 126 can be temporarily opened and closed accurately at a desired time according to the opening and closing timing of the intake valve 107.

  The intake control valve 126 in this embodiment is configured, for example, in the form of a butterfly valve or a flap valve, and is opened later than the opening timing of the intake valve 107 except during EGR stratified combustion control of the engine 100 described later. The actuator 125 is controlled based on a command from the electronic control unit (ECU) 200 so that the intake valve 107 is closed later than the closing timing. As a result, the air in the intake passage 120 located upstream from the intake control valve 126 flows into the combustion chamber 102 that is in a negative pressure state at the end of the intake stroke of the engine 100, and is a kind of inertial supercharging. Due to the effect, a large amount of air can be filled in the combustion chamber 102. In other words, in the supercharging using the intake control valve 126, the actual supercharging (hereinafter referred to as “supercharging”) is performed immediately after the start of control using the inertia of the intake air and the negative pressure generated on the downstream side of the intake control valve 126. This is referred to as impulse supercharging). Therefore, the control response at the time of low speed is superior to that of the turbo supercharging system, and so-called acceleration delay of the vehicle can be eliminated. The basic technology related to the intake control valve 126 is described in detail in "Impulses for Greater Driving Fun" which was announced on September 9 by Siemens VDO Automotive AG at the 2003 Frankfurt Motor Show. .

  Further, an intake pipe 121 having a surge tank 128 formed in the middle thereof detects an intake air temperature flowing through the intake passage 120 and outputs it to the electronic control unit 200, and an intake air sensor 120 in the intake passage 120. An intake pressure sensor 130 that detects the atmospheric pressure and outputs it to the electronic control unit 200 is attached. The attachment position of the intake air temperature sensor 129 and the intake pressure sensor 130 with respect to the intake pipe 121 may be upstream of the attachment position of the intake control valve 126, and is not limited to the position shown in FIG. As will be described later, when the engine 100 is a diesel engine, an accelerator opening sensor that outputs in proportion to the amount of depression of the accelerator pedal, instead of the intake pressure sensor 130 described above, to detect the load factor of the engine. 144 may be used.

  Further, harmful gas generated by combustion of the air-fuel mixture in the combustion chamber 102 is disposed in the middle of the exhaust pipe 132 that is connected to the cylinder head 106 so as to communicate with the exhaust port 105 and defines the exhaust passage 131 together with the exhaust port 105. A three-way catalyst 133 for detoxifying the substance is incorporated. It is also effective to incorporate a plurality of these three-way catalysts 133 in series along the exhaust passage 131.

  Therefore, the intake air supplied from the intake pipe 121 into the combustion chamber 102 through the air cleaner 122 forms an air-fuel mixture with the fuel injected from the fuel injection valve 101 into the combustion chamber 102, and is ignited by the spark of the spark plug 103. The exhaust gas thus generated is exhausted from the exhaust pipe 132 through the three-way catalyst 133 to the atmosphere.

  The cylinder block 135 in which the piston 134 reciprocates includes a water temperature sensor 137 that detects the temperature of the cooling water in the water jacket 136 formed in the cylinder block 135 and outputs the detected temperature to the electronic control unit 200, and a connecting rod 138. A crank angle sensor 140 that detects the rotational phase of the crankshaft 139 to which the piston 134 is connected via the crankshaft 139, that is, the crank angle, and outputs this to the electronic control unit 200 is attached. In the present embodiment, the crank angle sensor 140 is used as an engine speed sensor. Therefore, in the following description, the engine speed sensor 140 may be referred to.

  In addition, an exhaust gas recirculation gas passage 141 is branched from the middle of the exhaust pipe 132 that defines the exhaust passage 131 described above, and opens into the intake passage 120 between the intake valve 107 and the intake control valve 126 (the opening hole is opened). 145). An exhaust gas recirculation gas control valve 142 that opens and closes in response to an output signal from the electronic control unit 200 is provided in the exhaust gas recirculation gas passage 141. Reference numeral 143 denotes an EGR cooler that is provided as needed and cools the exhaust gas recirculation gas. Although not shown, the engine 100 may be configured as a supercharged engine.

  Here, when the engine 100 described above has a plurality of intake ports 104 and intake valves 107 per cylinder, the plurality of intake ports 104 may have different port shapes. Therefore, in this case, the relationship between the opening hole 145 of the exhaust gas recirculation gas passage 141 and the intake control valve 126 will be further described with reference to FIGS. 2 (A) and 2 (B). 2A and 2B, of the two intake ports 104 provided per cylinder, one of the intake ports 104, for example, the left-hand side of the drawing, is a helical intake port directed toward the center of the combustion chamber 102. The other intake port, for example, the right side, is a tangential intake port (hereinafter referred to as 104RR) directed in the direction of the peripheral wall of the combustion chamber 102. In the embodiment shown in FIG. 2A, a single intake control valve 126 is used in common for the helical intake port 104Fr and the tangential intake port 104RR. On the other hand, in the embodiment shown in FIG. 2B, two intake control valves 126 are used independently for each of the helical intake port 104Fr and the tangential intake port 104RR.

  Further, FIG. 2A shows a form in which the exhaust gas recirculation gas passage 141 is opened only by the helical intake port 104Fr with an opening hole 145, and FIG. 2B shows that the exhaust gas recirculation gas passage 141 is tangential. A form in which only the intake port 104RR is opened with the opening hole 145 is shown. It should be noted that whether the exhaust recirculation gas passage 141 is opened in any port shape does not matter whether the intake control valve 126 is common or independent. When the engine 100 is a gasoline engine, the exhaust gas recirculation gas passage 141 is opened at the tangential intake port 104RR with the opening hole 145 when the exhaust gas recirculation gas passage 141 is opened at the helical intake port 104Fr with the opening hole 145. As described later, this mode is suitable when the engine 100 is a diesel engine having a cavity at the top of the piston.

  The electronic control unit 200 is composed of a digital computer and includes a ROM (Read Only Memory), a RAM (Random Access Memory), a CPU (Microprocessor), an input port, an output port, and the like connected to each other via a bidirectional bus. The fuel injection valve 101, the ignition coil, the throttle actuator 123, the actuator 125, and the exhaust gas recirculation gas so that the engine 100 can be operated smoothly according to a preset program based on the detection signals from the various sensors described above. The operation of the control valve 142 and the like is controlled. Further, the fuel injection amount from the fuel injection valve 101 is preliminarily shown on a map or the like so as to be a predetermined ratio with respect to the intake amount corresponding to the opening degree of the throttle valve 124 based on the depression amount of an accelerator pedal (not shown). Is set.

  Next, among various controls including fuel injection control and ignition timing control executed by the electronic control unit 200, refer to the flowchart shown in FIG. 3 for the first form of the exhaust gas recirculation gas introduction control routine according to the present invention. To explain. This routine is executed each time the crank angle advances by a predetermined angle, for example.

  Therefore, in step S31 in the EGR gas introduction control routine, the engine speed calculated from the speed sensor 140 and the engine load factor detected from the intake pressure sensor 130 are read as parameters representing the operating state of the engine 100, and EGR is read. It is determined whether or not it is a stratified combustion region. This EGR stratified combustion region is determined and set in advance by experiments or the like as a region for suppressing the generation of NOx and smoke. Therefore, when not in the EGR stratified combustion region, this control routine is terminated.

  On the other hand, when it is the EGR stratified combustion region, the process proceeds to step S32, and based on the engine speed and the engine load factor read in step S31, the EGR is obtained from an appropriate value obtained in advance through experiments or the like and stored in the map. A quantity is acquired and determined. Then, in the next step S33, the opening / closing timing or opening period of the exhaust gas recirculation gas control valve 142 and the opening / closing timing or opening period of the intake control valve 126 are set in correspondence with the EGR amount.

  Next, in step S34 and step S35, the exhaust gas recirculation gas control valve 142 and the intake control valve 126 are opened / closed as follows in accordance with the opening / closing timing of the intake valve 107. That is, in step S34, the exhaust gas recirculation gas control valve 142 is opened with the intake control valve 126 closed, and only EGR is introduced into the combustion chamber 102. In step S35, after the exhaust gas recirculation gas control valve 142 is closed, the intake control valve 126 is opened, and fresh air is introduced into the combustion chamber 102. This will be described in more detail with reference to FIG.

  FIG. 4A is a graph showing the opening / closing timing of the intake valve 107, the intake control valve 126, and the exhaust gas recirculation gas control valve 142 in terms of the crank angle phase. In the figure, a solid double-headed arrow indicates the intake valve. 107 is opened at the top dead center (TDC) and closed at the bottom dead center (BDC), for example. The broken double-headed arrow indicates that the exhaust gas recirculation control valve 142 is opened at the top dead center (TDC) like the intake valve 107 and closed at a predetermined crank angle CA1 after the top dead center. is doing. Further, a double-pointed arrow indicated by a one-dot chain line indicates that the exhaust gas recirculation control valve 142 is closed at a predetermined crank angle CA1 after the top dead center, and at the same time, the intake control valve 126 is opened, and then the bottom dead center. It means that it is closed at a later predetermined crank angle CA2. Thus, in the intake stroke of the engine 100 in which the intake valve 107 is opened and the piston 134 is lowered from the top dead center, at the initial stage, the intake control valve 126 is closed and only the exhaust gas recirculation gas control valve 142 is opened. 4B, only the EGR gas is introduced into the combustion chamber 102 by the suction negative pressure. Then, after the exhaust recirculation gas control valve 142 is closed and the intake control valve 126 is opened at a predetermined crank angle CA1 after the top dead center, the intake air is replaced with EGR gas as shown in FIG. 4C. Is introduced into the combustion chamber 102. In this case, the EGR gas introduced in the initial stage is affected by the swirl, and an EGR gas layer is formed on the outer peripheral portion in the combustion chamber 102. Then, the fresh air is introduced into the central portion of the combustion chamber 102 by the introduced intake air. A layer is formed, and a stratified state of EGR gas and intake air is obtained.

  At this time, the downstream side of the intake control valve 126 in the intake passage of the engine 100 is constituted by the helical intake port 104Fr and the tangential intake port 104RR as described above, and the exhaust gas recirculation gas passage 141 is opened to the helical intake port 104Fr. In the case of the present embodiment, since the introduction of the EGR gas at the initial stage of the intake stroke is performed through the helical intake port 104Fr, the swirl of the EGR gas can be performed even when the lift amount of the intake valve 107 is small at the initial stage of the intake stroke. It can be increased, and a better stratified state of the outer EGR gas layer and the inner intake air layer can be obtained.

In the compression stroke, fuel is injected from the fuel injection valve 101 toward the intake air layer, and is ignited and burned by the spark plug 103. The fuel injection amount is preferably controlled so that the air-fuel ratio of the air-fuel mixture becomes the stoichiometric air-fuel ratio. In this way, the exhausted EGR gas has the same composition as the exhaust gas burned at the stoichiometric air-fuel ratio. In this way, the air-fuel mixture is stratified and the generation of NOx and smoke is suppressed by the EGR stratified combustion while reducing the fuel consumption by reducing the pumping loss.

  Next, a second embodiment of the exhaust gas recirculation gas introduction control routine executed by the electronic control unit 200 according to the present invention will be described with reference to the flowchart shown in FIG. This routine is also executed every time the crank angle advances by a predetermined angle. In addition, this 2nd form is a form suitable for the diesel engine which has the cavity 134A for combustion in the top part of the piston 134, as the engine 100 shows easily in FIG.6 (B), (C) mentioned later. .

  Therefore, in the EGR gas introduction control routine in the second embodiment, in step S51, as in the previous embodiment, the engine speed and accelerator opening sensor calculated from the speed sensor 140 are used as parameters representing the operating state of the engine 100. The engine load factor detected from 144 is read, and it is determined whether or not the engine is in the EGR stratified combustion region. When not in the EGR stratified combustion region, this control routine is terminated.

  When it is the EGR stratified combustion region, the process proceeds to step S52, and based on the engine speed and the engine load factor read in step S51, EGR is obtained from an appropriate value that is obtained in advance through experiments and stored in the map. In the next step S53, the opening / closing timing or opening period of the exhaust gas recirculation gas control valve 142 and the opening / closing timing or opening period of the intake control valve 126 are set in accordance with the EGR amount.

  Next, in step S54 and step S55, the intake control valve 126 and the exhaust recirculation gas control valve 142 are opened / closed as follows in accordance with the opening / closing timing of the intake valve 107. That is, in step S54, the intake control valve 126 is opened while the exhaust gas recirculation gas control valve 142 is closed, and fresh air is introduced into the combustion chamber 102. In step S55, after the intake control valve 126 is closed, the exhaust gas recirculation gas control valve 142 is opened, and the EGR gas is introduced into the combustion chamber 102. This will be described in more detail with reference to FIG.

  FIG. 6A is a graph showing the opening / closing timing of the intake valve 107, the intake control valve 126, and the exhaust gas recirculation gas control valve 142 in the crank angle phase, as in FIG. 4A. In FIG. The arrows indicate that the intake valve 107 is opened at, for example, top dead center (TDC) and closed at bottom dead center (BDC). The double-pointed arrow indicated by a one-dot chain line means that the intake control valve 126 is opened at the top dead center (TDC) like the intake valve 107 and is closed at a predetermined crank angle CA3 before the bottom dead center. ing. Further, the broken double-headed arrow indicates that the intake control valve 126 is closed at a predetermined crank angle CA3 before the bottom dead center, and at the same time, the exhaust gas recirculation gas control valve 142 is opened. It means that it is closed at a predetermined crank angle CA4.

  Thus, in the intake stroke of the engine 100 in which the intake valve 107 is opened and the piston 134 is lowered from the top dead center, the exhaust gas recirculation gas control valve 142 is closed and the intake control valve 126 is opened in the initial or middle period. Therefore, as schematically shown in FIG. 6B, fresh air is introduced into the combustion chamber 102 by a negative pressure. After the intake control valve 126 is closed and the exhaust gas recirculation gas control valve 142 is opened at a predetermined crank angle before the bottom dead center, EGR gas is used instead of fresh air as shown in FIG. It is introduced into the combustion chamber 102 in the cylinder. In this case, the fresh air introduced from the initial stage to the middle stage is maintained in the cavity 134A by the flow in the cylinder, and the EGR gas is introduced behind that state. This EGR gas is inside in the combustion chamber 102 in the cylinder, but circulates outside the intake air in the cavity 134A, and between the outer EGR gas layer and the inner intake air layer in the cavity 134A where fuel injection is directed. A stratified state can be obtained.

  At this time, the downstream of the intake control valve 126 in the intake passage of the engine 100 is configured by the helical intake port 104Fr and the tangential intake port 104RR as described above, and the exhaust recirculation gas passage 141 is connected to the tangential intake port 104RR. According to the open form, the introduction of EGR gas is delayed through the tangential intake port 104RR after the state in which the intake air is maintained in the cavity 134A due to the flow in the cylinder, so that EGR is performed later in the intake stroke. A stronger swirl of gas can be obtained, and a better stratified state of the outer EGR gas layer and the inner intake air layer can be obtained in the cavity 134A where fuel injection is directed.

  Furthermore, another embodiment of the present invention will be described with reference to FIGS. In this embodiment, the exhaust gas recirculation gas control valve 142 provided in the exhaust gas recirculation gas passage 141 has an extremely high control response as in the intake control valve 126 so that the exhaust gas recirculation gas passage 141 can be temporarily opened and closed. It is configured. Thus, it is possible to perform impulse supercharging of EGR gas. In order to distinguish from the exhaust gas recirculation gas control valve 142 in the previous embodiment, the exhaust gas recirculation gas supercharging control valve 142A will be referred to in the following description.

  Therefore, an exhaust gas recirculation gas introduction control routine according to another embodiment of the present invention will be described as a third embodiment with reference to the flowchart shown in FIG. This routine is also executed each time the crank angle advances by a predetermined angle, for example.

  Here, in step S71 in the EGR gas introduction control routine, the engine speed calculated from the speed sensor 140 and the engine load factor detected from the intake pressure sensor 130 are read as parameters representing the operating state of the engine 100, It is determined whether or not it is in the EGR stratified combustion region. As described above, the EGR stratified combustion region is determined and set in advance through experiments or the like as a region for suppressing the generation of NOx and smoke. Therefore, when not in the EGR stratified combustion region, this control routine is terminated.

  On the other hand, when it is the EGR stratified combustion region, the process proceeds to step S72, and based on the engine speed and the engine load factor read in step S71, the EGR is obtained from an appropriate value obtained in advance through experiments or the like and stored in the map. A quantity is acquired and determined. In the next step S73, the opening / closing timing or opening period of the exhaust gas recirculation gas supercharging control valve 142A and the opening / closing timing or opening period of the intake control valve 126 are set in correspondence with the EGR amount.

  Next, in step S74, the exhaust gas recirculation gas supercharging control valve 142A and the intake control valve 126 are opened and closed as follows in accordance with the opening and closing timing of the intake valve 107 so as to generate a negative pressure in the combustion chamber 102. . That is, in step S74, for example, after the intake valve 107 is opened at the top dead center (TDC), the exhaust gas recirculation gas supercharging control valve 142A and the intake control valve 126 are kept closed for a predetermined period. . Then, the process proceeds to step S75, in which the exhaust gas recirculation gas supercharging control valve 142A is temporarily opened, and only EGR is introduced into the combustion chamber 102. Further, the process proceeds to step S76, and the exhaust gas recirculation gas supercharging control valve 142A is closed while the intake control valve 126 is closed in order to grow the negative pressure in the combustion chamber 102. In the next step S77, the intake control valve 126 is opened after a predetermined period after the exhaust gas recirculation gas supercharging control valve 142A is closed, and fresh air is introduced into the combustion chamber 102. This will be described in more detail with reference to FIG.

  FIG. 8A is a graph showing the opening / closing timing of the intake valve 107, the exhaust gas recirculation gas supercharging control valve 142A, and the intake control valve 126 as a crank angle phase. In the figure, a solid double-headed arrow indicates For example, the intake valve 107 is opened at the top dead center (TDC) and closed at a predetermined crank angle CA5 after the bottom dead center (BDC). The broken double-headed arrow indicates that the exhaust gas recirculation supercharging control valve 142A is temporarily opened at a predetermined crank angle CA6 after top dead center (TDC) and closed at the crank angle CA7. ing. Further, a double-pointed arrow indicated by a one-dot chain line indicates that the exhaust recirculation gas supercharging control valve 142A is temporarily opened and closed at a predetermined crank angle after the top dead center, and then a predetermined angle before the bottom dead center. It shows that the intake control valve 126 is opened at CA8 and then closed at a predetermined crank angle CA9 after bottom dead center.

  Thus, in the intake stroke of the engine 100 in which the piston 134 descends from the top dead center, at the initial stage, as shown in FIG. 8B, the intake control valve 126 and the exhaust recirculation gas supercharging control valve 142A are closed. Therefore, a negative pressure is generated in the combustion chamber 102. Therefore, as shown in FIG. 8C, when the exhaust gas recirculation gas supercharging control valve 142A is temporarily opened, EGR gas is introduced in a supercharging state with dynamic pressure due to the negative pressure in the combustion chamber 102. The Then, after the exhaust gas recirculation gas supercharging control valve 142A is temporarily opened at a predetermined crank angle after top dead center, the intake control valve 126 remains closed as shown in FIG. 8 (D). Since the exhaust gas recirculation gas supercharging control valve 142A is also closed, the negative pressure in the combustion chamber 102 is grown again. Thereafter, as shown in FIG. 8E, when the intake control valve 126 is opened at a predetermined crank angle before bottom dead center, the intake air is supercharged with dynamic pressure due to the negative pressure in the combustion chamber 102. Introduced in Also in this case, the EGR gas introduced in the initial stage is affected by the swirl, and an EGR gas layer is formed on the outer peripheral portion in the combustion chamber 102. Next, the intake air introduced in the center portion of the combustion chamber 102 A fresh air layer is formed, and a stratified state of EGR gas and intake air is obtained.

  In this embodiment, the example in which the EGR gas is introduced first has been described. However, as described in the previous embodiment, the engine 100 is a diesel engine having a combustion cavity 134A at the top of the piston 134. In such a case, the intake air may be introduced first.

  Needless to say, the present invention can also be suitably used when the engine 100 includes a supercharger such as a supercharger or a turbocharger. When a supercharger is provided, the pressure on the outlet side of the exhaust gas recirculation gas passage 141 may be higher than the pressure on the inlet side. Even in such a case, the EGR gas can be stably introduced. Is possible.

1 is a conceptual diagram of an engine system showing an embodiment in which an exhaust gas recirculation gas introduction control device for an engine according to the present invention is applied to a gasoline engine. FIG. 4 is a perspective plan view showing the relationship between the opening hole of the exhaust gas recirculation gas passage and the intake control valve in the exhaust gas recirculation gas introduction control apparatus for an engine according to the present invention, wherein (A) shows the opening hole at the helical intake port; B) is a case where the opening hole is opened to the tangential intake port. It is a flowchart showing the 1st form of the control routine of the exhaust gas recirculation gas introduction control device concerning the present invention. (A) is a graph showing the opening / closing timing of the intake valve, the intake control valve, and the exhaust gas recirculation gas control valve in terms of the crank angle phase, and (B) and (C) are those in which EGR gas and intake air are introduced into the combustion chamber. It is a schematic diagram which shows a mode roughly. It is a flowchart showing the 2nd form of the control routine of the exhaust gas recirculation gas introduction control device concerning the present invention. (A) is a graph showing the opening / closing timing of the intake valve, the intake control valve, and the exhaust gas recirculation gas control valve in terms of the crank angle phase, and (B) and (C) are those in which EGR gas and intake air are introduced into the combustion chamber. It is a schematic diagram which shows a mode roughly. It is a flowchart showing the 3rd form of the control routine of the exhaust gas recirculation gas introduction control device concerning the present invention. (A) is a graph showing the opening / closing timing of the intake valve, the exhaust gas recirculation gas supercharging control valve, and the intake control valve as a crank angle phase, and (B), (C), (D), and (E) are EGR gas and intake. It is a schematic diagram which shows a mode that air is introduce | transduced in a combustion chamber.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Engine 101 Fuel injection valve 102 Combustion chamber 103 Spark plug 104 Intake port 105 Exhaust port 106 Cylinder head 107 Intake valve 108 Exhaust valve 120 Intake passage 121 Intake pipe 122 Air cleaner 123 Throttle actuator 124 Throttle valve 125 Actuator 126 Intake control valve 128 Surge tank 130 Intake pressure sensor 131 Exhaust passage 132 Exhaust pipe 133 Three-way catalyst 134 Piston 135 Cylinder block 136 Water jacket 137 Water temperature sensor 138 Connecting rod 139 Crankshaft 140 Crank angle sensor 200 ECU
TDC top dead center BDC bottom dead center

Claims (5)

An intake control valve provided in an intake passage upstream of the intake valve and capable of opening and closing in accordance with the opening and closing timing of the intake valve;
An exhaust gas recirculation gas control valve provided in an exhaust gas recirculation gas passage that opens in an air intake passage between the intake valve and the intake control valve;
Engine operation region determination means for determining whether or not the engine is in the exhaust gas recirculation gas introduction region;
An opening / closing operation timing control means for controlling the intake control valve and the exhaust gas recirculation gas control valve with different opening / closing operation timings when the engine operation region determination means determines that the engine is in the exhaust gas recirculation gas introduction region; ,
An exhaust recirculation gas introduction control device for an engine, comprising: The engine is a gasoline engine,
2. The exhaust gas recirculation gas introduction control device for an engine according to claim 1, wherein the opening / closing operation timing control unit performs control so that the intake air control valve is opened after the exhaust gas recirculation gas control valve is closed. 3.   The downstream side of the intake control valve in the intake passage is configured by a helical intake port and a tangential intake port, and the exhaust gas recirculation gas passage is opened to the helical intake port. Engine exhaust recirculation gas introduction control device. The engine is a diesel engine having a cavity at the top of a piston,
2. The exhaust gas recirculation gas introduction control device for an engine according to claim 1, wherein the opening / closing operation timing control means performs control so that the exhaust gas recirculation gas control valve is opened after the intake air control valve is closed. The downstream side of the intake control valve in the intake passage is constituted by a helical intake port and a tangential intake port, and the exhaust gas recirculation gas passage is opened to the tangential intake port. Engine exhaust gas recirculation gas introduction control device.

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