JP4957542B2 - Intake control device for internal combustion engine - Google Patents

Description

  The present invention relates to a technical field of an intake control device for an internal combustion engine configured to be capable of inertia supercharging by opening / closing control of an intake control valve.

  In this type of technical field, a device having a device for variably controlling the valve timing of the intake valve has been proposed (see, for example, Patent Document 1). According to the intake control device for an internal combustion engine disclosed in Patent Document 1 (hereinafter referred to as “prior art”), an effective intake period in which both the intake valve and the intake control valve are open is set as an intake control valve. It is said that an ideal intake characteristic can be obtained by controlling according to the operating state of the internal combustion engine by cooperative control with the variable valve timing mechanism.

  In a technical field different from this type of technical field, it has been proposed to increase the intake charging efficiency by operating the intake valve with a low lift and small working angle in a low, medium and high load region (for example, Patent Document 2).

  Further, in a technical field different from this type of technical field, an intake control valve that opens and closes an intake passage for each cylinder is arranged immediately upstream of each cylinder, and the intake valve is opened and closed by a control valve driving means. A device that realizes the same function as the variable valve timing device without controlling the valve opening period has been proposed (see, for example, Patent Document 3).

JP 2006-46293 A Japanese Patent Laid-Open No. 5-306637 Japanese Patent Laid-Open No. 11-13493

  In a so-called single valve type intake system in which a plurality of cylinders share and share an intake control valve, the communication pipe volume downstream of the intake control valve is relatively large, so that intake air is discharged through the intake valve at the end of the intake stroke. The so-called intake air blowback tends to reduce the intake air charging efficiency. On the other hand, in this type of one-valve type intake system, when the intake control valve is opened across the intake stroke and other strokes, the intake stroke of other cylinders can be affected, which is shown in the prior art. It is practically difficult to apply such control. That is, the conventional technique has a technical problem that the charging efficiency of the intake air is likely to decrease in each of the plurality of cylinders.

  The present invention has been made in view of the above-described problems, and it is an object of the present invention to provide an intake control device for an internal combustion engine that can improve the charging efficiency of intake air in each of a plurality of cylinders in a single valve type intake system. And

In order to solve the above-described problems, an intake control device for an internal combustion engine according to the present invention is provided in a vehicle, and is installed in a plurality of cylinders, an intake passage shared among the plurality of cylinders, and in an open / closed state. An intake control valve for an internal combustion engine, comprising: an intake control valve capable of generating intake pulsation in response, and variable valve operating means capable of changing the opening and closing timing of the intake valve in each of the plurality of cylinders; A first control means for controlling the intake control valve so as to perform inertia supercharging due to the pulsation of the intake air according to driving conditions of the vehicle; and A second control means for controlling the variable valve means so that an overlap amount during a valve opening period of the intake valve is smaller than an overlap amount when the inertia supercharging is not performed; comprising the first When the inertia supercharging is to be stopped, the control means controls the intake control valve so that the inertia supercharging is stopped, and the second control means is configured to stop the inertia supercharging. Prior to control of the control valve, the variable valve operation is performed so that the opening / closing timing of each intake valve returns to a predetermined reference timing that is determined in advance when the inertia supercharging is not performed. When the inertia supercharging is to be executed, the first control means controls the inertia supercharging before the variable valve operating means is controlled to reduce the overlap amount. The intake control valve is controlled so as to be made .

  The "internal combustion engine" according to the present invention has a plurality of cylinders, and various fuels such as gasoline, light oil, various alcohols, or a mixed fuel of various alcohols and gasoline, or the like in each of the cylinders, or The force generated when an air-fuel mixture containing various fuels explodes or burns can be taken out as a driving force through a physical or mechanical transmission path such as a piston, a connecting rod and a crankshaft. It is a concept that encompasses various institutions. An “intake engine control device for an internal combustion engine” relating to this type of internal combustion engine includes intake air (ie, intake air as air sucked from the outside world) as a part of the concept, and the intake air itself. Or, for example, when an exhaust gas recirculation device such as an EGR device is provided, for example, a mixture of EGR gas (that is, a part of exhaust gas) and the intake air according to the open / close state of a flow rate adjusting means such as an EGR valve, etc. The device can control the supply of various forms of the above.

  The “intake passage” in the intake control apparatus for an internal combustion engine according to the present invention is the intake passage described above. As a preferred embodiment, for example, an air cleaner, an air flow meter, a throttle valve (ie, an intake throttle valve). The surge tank, the intake port, and the like can be connected or communicated with each other as appropriate, for example, in the form of a single or a plurality of tubular members. Further, as a preferred embodiment, the internal combustion engine according to the present invention is a part formed by excluding a part to be provided in an exhaust system such as a turbocharger (of course, a turbine or the like) in the intake passage. In this case, the downstream side (in addition, “downstream” and “upstream” is one of the directional concepts based on the direction of intake air flow. In this case, An intake air cooling means such as an intercooler may be provided on the downstream side (that is, the cylinder side). The intake air cooling means is a physical unit capable of cooling intake air supplied via a supercharger (may be irrelevant whether or not supercharging by the supercharger is performed in practice). Means having mechanical, mechanical, electrical, magnetic or chemical aspects, at least somewhat more and relatively cooling the intake air, thereby increasing the intake air density relatively Efficiency can be improved.

  In the internal combustion engine according to the present invention, the intake passage is shared by a plurality of cylinders. Here, the plurality of cylinders sharing the intake passage may not be all of the cylinders provided in the internal combustion engine according to the present invention, and conceptually indicates at least a plurality of cylinders among the plurality of cylinders provided in the internal combustion engine. For example, when the cylinder arrangement of the internal combustion engine according to the present invention has a so-called V type, a plurality of cylinders belonging to two cylinder groups (also referred to as banks) facing each other at a predetermined included angle May correspond to “a plurality of cylinders” according to the present invention, and when the cylinder arrangement has a so-called in-line type, all cylinders (of course, conceptually, some cylinders) May be equivalent to "a plurality of cylinders" according to the present invention.

  An internal combustion engine according to the present invention is provided with an intake control valve capable of generating intake air pulsation in accordance with an open / close state in an intake passage, and the intake system is configured as a so-called one-valve intake system. This intake control valve is capable of adjusting the intake amount as the intake amount in accordance with, for example, an open / close state that can be controlled in a binary, stepwise or continuous manner. 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, and when the internal combustion engine is equipped with a so-called intake throttle valve such as a throttle valve, As a preferred embodiment, it is installed on the downstream side of the intake throttle valve. Incidentally, the single valve type refers to a configuration in which one intake control valve is provided in the intake passage as a preferred form, but conceptually, as long as it can function substantially as a single valve body, the number thereof is It is not limited at all.

  On the other hand, the internal combustion engine according to the present invention is physically and mechanically different from the intake valve that can change the opening and closing timing of the intake valve as one element that can define the communication state between the cylinder interior and the intake passage. And variable valve operating means as a concept including various driving force applying means capable of applying various mechanical, electrical or magnetic driving forces. In addition, this type of variable valve means may be embodied in various modes such as VVT (Variable Valve Timing) having a variable working angle function, a cam-by-wire, or an electromagnetically driven valve.

  The intake control device for an internal combustion engine according to the present invention can be configured as various processing units such as an ECU (Electronic Control Unit), various controllers, various computer systems such as a microcomputer device, or the like when operating. The inertial supercharging (pulse supercharging or impulse charge, etc.) according to the vehicle operating conditions as a concept that can include, for example, the engine speed or required load of the internal combustion engine or various index values corresponding to them The intake control valve is controlled so that the control is performed.

  Inertia supercharging is a preferred form of opening the intake control valve after an appropriate time elapse (which may be defined as an angle concept by a crank angle or the like) after the intake valve is opened (ie, intake air intake). Combustion of each cylinder that generates a positive pressure wave by opening the valve in the state where the downstream side of the control valve is negative pressure and the upstream side of the intake control valve is at or above atmospheric pressure. The negative pressure wave is reflected near the entrance of the chamber, and this negative pressure wave is reflected at the open end again, for example, at an opening of a surge tank, for example, arranged in series or in parallel with the intake passage. When natural intake is performed using intake air pulsation that can take the form of a pressure wave or the like (as a preferred form, 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 air control valve is, as a preferred form, taking a larger amount of intake air into the cylinder in the intake stroke as compared to this type of pulsation (that is, To supercharge).

  The control performed by the first control unit on the intake control valve is, for example, an opening / closing timing, an opening period or an opening degree of the intake control valve (that is, the valve opening degree). This is a concept that includes control of the degree of opening and opening / closing state uniquely, and includes, for example, an intake valve (that is, a valve that controls the communication state between the combustion chamber and the intake passage as a preferred embodiment). This includes the control of synchronizing the valve closing timing and the timing at which the peak of the pulsating wave (positive pressure wave) of the intake reaches the intake valve (not necessarily indicating that they coincide with each other). The intake control valve is mainly intended to realize inertia supercharging using intake pulsation (however, apart from the generation of this type of pulsation, for example, opening / closing operation of an intake throttle valve such as a throttle valve) The intake control valve according to the present invention replaces the action of the intake throttle valve such as a throttle valve when the intake air adjustment (intake throttle), which can be suitably performed by the above, can be practiced to the extent that there is no practical problem. (Or, conversely, the intake throttle valve may replace its function as an intake control valve according to the present invention). You may install in the position close | similar to the intake valve of each cylinder to such an extent that it may produce a pulsation.

  On the other hand, this type of inertia supercharging is a preferred form, for example, when the engine rotational speed is low (for example, the engine rotational speed is a region where the operating speed of the intake control valve can follow, or the pulsation that the intake air originally has) And the pulsation generated by the opening / closing control of the intake control valve), and the required load is originally, for example, that belongs to a low rotation region excluding a high rotation region as a region where a significant difference in effect is difficult to appear) This may be performed when the engine belongs to a high load region excluding a low load region that does not require supercharging, and is often performed in a part of the operation region of the internal combustion engine. Accordingly, there may be an operation region in which inertia supercharging is not necessarily performed, but the opening / closing timing of the intake valve in such an operation region is often different from that at the time of execution of inertia supercharging.

  For example, when inertia supercharging is not performed, as a preferred embodiment, the opening timing of the intake valve is set on the more advanced side than TDC (Top Death Center), and the closing timing is BDC ( Bottom Death Center: Set on the retarded side from the bottom dead center). Therefore, in a plurality of cylinders that share an intake control valve, the end of the intake stroke of at least one cylinder (here, at least the period during which the intake valve is opened) and the initial stage of the intake stroke of the other cylinders are somewhat different. Can overlap.

  On the other hand, in a configuration in which the intake control valve is shared by and shared by a plurality of cylinders, as a preferred embodiment, the intake control valve is in the intake stroke for each cylinder so as not to affect the intake stroke of the other cylinders. It may be controlled to open and close. However, if the opening / closing timing of the intake valve at the time of non-execution of inertia supercharging as described above is applied at the time of execution of inertia supercharge, the intake stroke is performed in an overlap period in which the valve opening periods of the intake valves overlap among a plurality of cylinders. The intake air blows back from the inside of the cylinder at the end and flows into the cylinder at the beginning of the intake stroke, so that the efficiency of charging the intake air is reduced in the former, and the negative pressure necessary for inertial supercharging is also hindered in the latter Eventually, a decrease in the charging efficiency of the intake air may manifest at least to the extent that it is difficult to overlook in practice.

  Therefore, according to the intake control apparatus for an internal combustion engine according to the present invention, during its operation, the inertial force is controlled by the second control means that can be configured as various processing units such as an ECU, various controllers or various computer systems such as a microcomputer device. When supercharging is performed, the overlap amount of the intake valve opening period between each of the plurality of cylinders (hereinafter, referred to as “intake overlap amount” as appropriate) is equal to the overlap amount when inertial supercharging is not performed. The variable valve operating means is controlled so as to be smaller than the lap amount.

  Here, in particular, for all the cylinders, the intake valve overlap and the valve close timing are respectively advanced or retarded by the same amount (that is, where only the phase angle is variable). In view of the fact that there is no change in the amount, the control for reducing the intake overlap amount according to the second control means is simply the operation angle (or lift amount) of the intake valve. This corresponds to reduction or reduction. If it supplements, the variable valve means which concerns on this invention is the concept which covers the mechanism, apparatus, and system which can make the working angle of an intake valve variable at least.

According to the intake control device of the present invention, when the inertia supercharging is executed, the intake overlap amount is reduced in this way, so that the return of intake air that can occur at the end of the intake stroke is suppressed, and time series A decrease in intake charging efficiency in each of the plurality of cylinders that reach the intake stroke before and after the upper phase is suppressed. In other words, compared to the case where this kind of control is not performed, the intake charging efficiency in each of the plurality of cylinders can be considerably improved.
In the intake control device for an internal combustion engine according to the present invention, the first control means controls the intake control valve so that the inertia supercharging stops when the inertia supercharge should be stopped, and the second control. The means controls the variable valve operating means so that the opening / closing timing of the intake valve in each of the plurality of cylinders is restored to a predetermined reference time before the intake control valve is controlled to stop the inertia supercharging. .
That is, the first control means, for example, when the inertia supercharging should be stopped due to circumstances such as the vehicle operating condition deviating from the inertia supercharging execution condition, for example, the intake control valve is set at a predetermined position (preferably Is a position corresponding to the fully open position, and is stopped at least at a position that does not inhibit intake air.
On the other hand, when inertial supercharging is stopped in this way, taking into account the power performance, environmental performance or economic performance of the internal combustion engine, the opening / closing timing of the intake valve is normal (that is, when inertial supercharging is not performed here). It may be necessary to switch to a mode adapted to For example, it may be necessary to advance the valve opening timing or further retard the valve closing timing, for example. However, when the variable valve means has any physical, mechanical, mechanical, electrical, or magnetic configuration, the variable valve means is instructed to perform this type of switching and then actually Until the intake valve opening / closing timing reaches the control target, there is a considerable delay in response to some degree. This response delay tends to be clearly larger than the response delay of the intake control valve in view of the difference in the physical configuration between the intake control valve and the variable valve operating means. In the transient period corresponding to this response delay, For example, a decrease in power performance or the like due to the stoppage of the supply and the opening / closing timing of the intake valve deviating from the optimum value may become apparent.
Therefore, the second control means opens / closes the intake valve in each cylinder before the first control means controls the intake control valve to stop the inertia supercharging when the inertia supercharging should be stopped. The time is returned to a predetermined reference time. At this time, the control of the intake control valve according to the first control means may be executed when the opening / closing timing of the intake valve returns to the reference time, or simply prior to the control of the first control means in time series. Only the control of the second control means may be executed.
As described above, the “reference time” is an opening / closing time optimized when inertia supercharging is not performed. For example, the reference time is experimentally, empirically, theoretically, or based on simulation. The power performance, environmental performance, and economic performance of the internal combustion engine during non-execution of inertia supercharging may be determined so as to satisfy the required values.
Further, in the intake air control apparatus for an internal combustion engine according to the present invention, the first control means, prior to the variable valve means being controlled to reduce the overlap amount when the inertia supercharging is to be executed. The intake control valve is controlled so that inertia supercharging is performed.
That is, when the inertial supercharging is to be executed, the first control unit executes the inertial supercharging before the second control unit attempts to reduce the overlap amount through the control of the variable valve operating unit. To do. Accordingly, as the opening / closing timing of the intake valve gradually shifts to the opening / closing timing suitable for inertial supercharging by the control of the variable valve means by the second control unit, It is possible to gradually increase the charging efficiency, and to suppress a decrease in the output of the internal combustion engine at the start of inertia supercharging.
It should be noted that the control mode for starting the control of the intake control valve prior to the start of the control of the variable valve means in this way may be free as long as the output fluctuation can be suppressed at least to some extent. The control of the intake valve may be delayed for a predetermined delay time from the timing at which the inertia supercharging should be started, which is defined by the state of the engine (ie, the opening / closing control of the intake control valve is started at this time).

  In one aspect of the intake control device for an internal combustion engine according to the present invention, the second control means includes the one cylinder and the other cylinder that reach the intake stroke before and after the time series upper phase in the other cylinder. The variable valve operating means is controlled so that the opening timing of the intake valve is synchronized with the closing timing of the intake valve in the one cylinder.

  According to this aspect, the intake overlap amount between the cylinders that reach the intake stroke before and after the time series upper phase is small enough to be regarded as zero or zero (that is, “synchronization” is not necessarily on the time series. It is possible to suppress as much as possible a decrease in the charging efficiency of the intake air in each of the plurality of cylinders as much as possible. It becomes possible to improve as much as possible.

  In another aspect of the intake control device for an internal combustion engine according to the present invention, in the process of changing the opening / closing timing of the intake valve in each, the opening / closing of the intake control valve according to the amount of change in the opening / closing timing of the intake valve in each A correction unit for correcting the time is further provided.

  According to this aspect, for example, the opening / closing timing of the intake control valve can be set according to the amount of change in the opening / closing timing of the intake valve by the correction means that can be configured as various processing units such as an ECU, various controllers or various computer systems such as a microcomputer device. Since the correction is made, a sudden change in the intake charging efficiency between the execution and non-execution of inertia supercharging is suppressed, and the comfort performance of the vehicle can be improved. Note that “the process of changing the opening / closing timing of the intake valve” is a preferred embodiment in which the second control means changes the opening / closing timing of the intake valve between when the inertia supercharging is executed and when it is not executed. However, it does not necessarily exclude a process in which the opening / closing timing of the intake valve is changed for other reasons.

  Such an operation and other advantages of the present invention will become apparent from the embodiments described below.

<Embodiment of the Invention>
Various preferred embodiments of the present invention will be described below with reference to the drawings.
<First Embodiment>
<Configuration of Embodiment>
First, the configuration of the engine system 10 according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram conceptually showing the configuration of the engine system 10.

  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. 1 is an example of an “intake control device for an internal combustion engine”. The ECU 100 is configured to be able to execute later-described valve drive control in accordance with a control program stored in the ROM.

  The ECU 100 is an integrated electronic control unit configured to function as an example of the “first control unit” and the “second control unit” according to the present invention. All are configured to be executed by the ECU 100. However, the physical, mechanical, and electrical configurations of each of the units according to the present invention are not limited to this. For example, each of these units includes a plurality of ECUs, various processing units, various controllers, a microcomputer device, and the like. It may be configured as various computer systems.

  The engine 200 is an in-line four-cylinder gasoline engine that is an example of an “internal combustion engine” according to the present invention that uses gasoline as fuel. The outline of the engine 200 will be described. The engine 200 has a configuration in which four cylinders 202 are arranged in parallel in a cylinder block 201. Then, the air-fuel mixture containing the fuel is compressed in the compression process in each cylinder, and the force generated when ignited by the ignition operation of the ignition device 203 is applied to the crankshaft (not shown) via a piston and a connecting rod (not shown), respectively. It is configured to be converted into a rotational motion. 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. Below, the principal part structure of the engine 200 is demonstrated with a part of the operation | movement. Since the configurations of the individual cylinders 202 are equal to each other, only one cylinder 202 will be described here. However, when the cylinders are distinguished from each other, each of these four cylinders is appropriately expressed as “first cylinder”, “second cylinder”, “third cylinder”, and “fourth cylinder”.

  In FIG. 1, intake air that is air guided from the outside is guided to an intake pipe 204 that 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.

  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. Two intake ports are provided for each cylinder 202, and each 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.

  An injection valve of an injector (not shown) for fuel injection is exposed at the intake port, and is configured to be able to inject gasoline as fuel into the intake port. The injector drive system is electrically connected to the ECU 100 and is controlled by the ECU 100 to the upper level. That is, the operation of the injector is controlled by the ECU 100. The fuel injected through the injector is mixed to some extent with the intake air at the intake port, and is sucked into the cylinder 202 in the intake stroke as the above-described mixture. That is, this air-fuel mixture is an example of “intake” according to the present invention. Note that the intake air-fuel mixture is further mixed in the intake stroke and the subsequent compression stroke, and ignited and ignited by ignition control of the ignition device 203 (controlled by the ECU 100) performed in the vicinity of the compression TDC ( That is, it is configured to explode).

  In this embodiment, the injector is a so-called electronically controlled port injector, and fuel is injected into the intake port. However, the fuel injection mode is not limited in any way. For example, this type of port injector is used. Instead of or in addition, an in-cylinder direct injection system composed of, for example, a common rail system or a unit injector that can inject fuel directly into the high-temperature and high-pressure cylinder 202 may be employed.

  The communication state between the intake port and the cylinder 202 is controlled by an intake valve 207 provided at each intake port. The intake valve 207 is fixed to the intake camshaft 208 that rotates in conjunction with the crankshaft. The cam profile of the intake cam 209 that has an elliptical cross section perpendicular to the extending direction of the intake camshaft 208 (in short, The opening / closing characteristics are defined according to the shape), and the intake port and the inside of 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.

  The combusted air-fuel mixture or the partially unburned air-fuel mixture is guided to the exhaust manifold 213 as exhaust gas via an exhaust port (not shown) when the exhaust valve 210 that opens and closes in conjunction with opening and closing of the intake valve 207 is opened. It has become. The exhaust valve 210 is fixed to the exhaust camshaft 211 that rotates in conjunction with the crankshaft, and the cam profile of the exhaust cam 212 having an elliptical cross section perpendicular to the extending direction of the exhaust camshaft 211 (in short, The opening / closing characteristics are defined according to the shape), and the exhaust port and the cylinder 202 can be communicated with each other when the valve is opened. The exhaust gas collected in the exhaust manifold 213 is supplied to the exhaust pipe 214 communicating with the exhaust manifold 213.

  A turbine 216 is installed in the exhaust pipe 214 so as to be accommodated in the turbine housing 215. The turbine 216 is a ceramic impeller configured to be rotatable about a predetermined rotation axis by the pressure of exhaust gas (that is, exhaust pressure) guided to the exhaust pipe 214. The rotating shaft of the turbine 216 is shared with the compressor 218 installed in the intake pipe 204 so as to be accommodated in the compressor housing 217. When the turbine 216 is rotated by exhaust pressure, the compressor 218 is also centered on the rotating shaft. It is configured to rotate.

  The compressor 218 is configured to be able to pump and supply intake air sucked into the intake pipe 204 from the outside via the air cleaner 219 to the downstream side by the pressure accompanying its rotation. A so-called supercharging is realized by the pumping effect. That is, in the engine 200, the turbine 216 and the compressor 218 constitute a kind of turbocharger. In the following description, the term “turbocharger” will be used as appropriate as a comprehensive concept including the turbine 216 and the compressor 217.

  A three-way catalyst 219 is installed in the exhaust pipe 214. The three-way catalyst 219 is a catalytic converter that can purify HC (hydrocarbon), CO (carbon monoxide), and NOx (nitrogen oxide) in the exhaust gas simultaneously or continuously. Further, a water temperature sensor 220 is disposed in the cylinder block 201 that accommodates the cylinder 202. Inside the cylinder block 201, a water jacket as a cooling water flow path for cooling the cylinder 202 is stretched. Inside the water jacket, LLC as cooling water is circulated and supplied by the action of a circulation system (not shown). ing. The water temperature sensor 220 has a configuration in which a part of the detection terminal is exposed inside the water jacket, and is configured to be able to detect the temperature of the cooling water. The water temperature sensor 220 is electrically connected to the ECU 100, and the detected coolant temperature is grasped by the ECU 100 at a constant or indefinite period.

  A hot wire type air flow meter 221 capable of detecting the mass flow rate of the intake air is installed on the upstream side of the compressor 218. The air flow meter 221 is electrically connected to the ECU 100, and the detected intake air amount is grasped by the ECU 100 at a constant or indefinite period. In the present embodiment, the detected intake air amount is uniquely related to the amount of intake air (ie, the intake air amount) sucked into the cylinder 202, and is an index that defines the actual load of the engine 200. Treated as a value.

  In the intake pipe 204, an intercooler 222 is installed on the downstream side of the compressor 218 and the upstream side of the throttle valve 205. The intercooler 222 has a heat exchange wall inside thereof, and when supercharged intake air passes (the same is true even in a low rotation region where the compressor 218 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 222, so that the supercharging via the compressor 218 can be performed more efficiently.

  Here, a surge tank 223 is installed on the downstream side of the throttle valve 205 in the intake pipe 204. The surge tank 223 suppresses irregular pulsation of the intake air supplied while appropriately receiving the above-described turbocharger supercharging action, and stably supplies the intake air to the downstream side (that is, the cylinder 202 side). In addition, the storage means is 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.

  A single impulse valve 224 is provided in the vicinity of the connection portion with the communication pipe 206 on the downstream side of the surge tank 223 in the intake pipe 204. The impulse valve 224 has an opening degree defined by the position of the valve body, a fully-closed opening degree that blocks communication between the intake pipe 204 and the communication pipe 206, and almost complete communication between the intake pipe 204 and the communication pipe 206. It is an electromagnetic control valve as an example of the “intake control valve” according to the present invention, which is configured to continuously change between the fully opened opening. The impulse valve 224 is configured such that its opening degree is controlled by 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 opening degree of the impulse valve 224 is controlled by the ECU 100.

  On the other hand, engine 200 includes variable working angle type VVT 226. The variable working angle type VVT 226 is an example of the “variable valve operating means” according to the present invention configured to be able to continuously change the phase and the working angle of the intake valve 207.

  The variable working angle type VVT 226 includes a plurality of drive systems such as a vane drive hydraulic actuator and a swing cam drive motor. The drive system is electrically connected to the ECU 100 and its operation state is controlled by the ECU 100. Thus, the operation state is controlled by the ECU 100 to the upper level. The variable working angle type VVT 226 has a known vane phase variable function using a hydraulic actuator and a known lost motion type working angle (ie, valve lift amount) variable function using a swing cam driven by a motor. It is a device having both.

  The configuration of the variable working angle type VVT 226 is a known one, and the configuration of the “variable valve mechanism” according to the present invention is, for example, a cam-by-wire device (that is, the intake cam is driven by a motor or the like). And other known modes such as an electromagnetically driven valve device (that is, a device that does not have an intake cam and can directly control the opening and closing of the intake valve by electromagnetic drive means such as a solenoid). Detailed description will be omitted.

  In the description of the intake valve 207, it is described that the intake valve 207 has one opening / closing characteristic defined by the cam profile of the intake cam 208. This is because the operation of the variable working angle type VVT 226 is described. The cam profile of the intake cam 208 affects the opening / closing characteristics of the intake valve 207 with respect to one operating state of the variable operating angle VVT 226 (that is, the vane position, the pivot point position of the swing cam, etc.). It means to prescribe.

  In the engine system 10 according to the present embodiment, the engine 200 that is a gasoline 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 the gasoline engine. Of course, a diesel engine, an engine using an alcohol mixed fuel, or the like may be used. Further, for the purpose of preventing the explanation from being complicated, the engine 200 according to the present embodiment is not equipped with an exhaust gas recirculation device such as an EGR device. However, as a preferred embodiment, the engine 200 is equipped with an exhaust gas recirculation device. It may be. Here, in view of the configuration in which the exhaust gas recirculation device is not mounted, in the engine 200 according to the present embodiment, the intake air sucked into each cylinder 202 through the intake port passes through the intake pipe 204 except for the fuel injected by the injector. It is comprised only by the intake air led through.

  The required load of the engine 200 is determined according to an accelerator opening degree Ta that is an operation amount (that is, an operation amount by a driver) of an accelerator pedal (not shown). 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.

<Operation of Embodiment>
<Overview of impulse charge>
In the engine system 10, the impulse charge is executed by the ECU 100 appropriately controlling the open / close state of the impulse valve 224 in the process of executing the valve drive control described later. Here, the impulse charge refers to inertial supercharging utilizing intake air pulsation caused by opening and closing of the impulse valve 224.

  More specifically, for example, when the impulse valve 224 is closed, the intake valve 207 of one cylinder 202 is opened, and when the intake stroke of the cylinder is started, the impulse valve 224 is closed. Therefore, as the piston of the cylinder 202 descends, the pipe pressure of the communication pipe 206 becomes negative, and the pressure difference from the pipe pressure of the intake pipe 204 that is maintained at atmospheric pressure or higher due to atmospheric pressure or supercharging increases. In this state, when the impulse valve 224 is opened (that is, opened during the opening period after the opening timing of the intake valve 207), the intake pipe 204 and the corresponding cylinder 202 (that is, the intake stroke at that time). And the intake air flows into the combustion chamber inside the cylinder 202 at once as intake air via the impulse valve 224.

  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 sequentially through the communication pipe 206 and the impulse valve 224, and reaches the combustion chamber again as a positive pressure wave whose phase is inverted by reflection at the open end at the open hole. When the peak of the positive pressure wave reaches the combustion chamber (or to the intake valve 207) (not necessarily limited to that point in time, but includes that point as long as the charging efficiency of the intake can be improved to some extent) The valve opening timing of the impulse valve 224 may be such that the positive pressure wave reaches the combustion chamber by closing the intake valve 207 or at the timing when the intake valve 207 is closed. By controlling this, the pressure in the combustion chamber rises, and the charging efficiency of the intake air is improved. Impulse charging using the impulse valve 224 is qualitatively executed in this way.

<Details of valve drive control>
Next, the details of the valve drive control will be described with reference to FIG. FIG. 2 is a flowchart of the valve drive control.

  In FIG. 2, the ECU 100 acquires the driving conditions of the vehicle (step S101). In the present embodiment, the engine speed Ne and the accelerator opening degree Ta are acquired as the operating conditions. When the engine rotation speed Ne and the accelerator opening degree Ta are acquired, it is determined whether or not the acquired operation condition corresponds to the impulse charge region (step S102).

  Here, the impulse charge region will be described with reference to FIG. FIG. 3 is a schematic diagram of the impulse charge region.

  In FIG. 3, the impulse charge region is a region corresponding to the hatched region shown in the two-dimensional coordinate system in which the accelerator opening degree Ta and the engine rotational speed Ne are arranged on the vertical axis and the horizontal axis, respectively. More specifically, it is assumed that the range of engine rotation speeds that can be taken by the engine 200 is not less than the minimum rotation speed NeL (which is the minimum rotation speed at which self-rotation is possible) and not more than the maximum rotation speed NeH (which is a so-called rev limit). When the accelerator opening degree Ta changes from 0% (that is, fully closed) to 100% (that is, fully opened), the impulse charge region has NeL ≦ Ne ≦ Neth (Neth <NeH) and Tath ≦ Ta ≦ 100. Qualitatively speaking, it is a low rotation and high load region.

  The minimum rotation speed NeL is a value of about 800 rpm, for example, and Neth is a judgment reference value, which is a value of about 2000 rpm. Further, Tath is a reference value for the accelerator opening, and is a value that can be used to determine that inertial supercharging is necessary in terms of required load. In other words, in the low load region below the reference value Tath, it is not necessary to increase the intake charge amount from the beginning, and therefore it is not necessary to perform impulse charge.

  Returning to FIG. 2, when the acquired operating condition does not correspond to the impulse charge region (step S102: NO), the ECU 100 returns the process to step S101 and repeats a series of processes. That is, in this case, the impulse valve 224 is fixed at the fully open position as the default position, and the opening / closing timing of the intake valve 207 is an example of the reference timing (that is, the “predetermined reference timing” according to the present invention). This is an example of the opening / closing timing that defines “the amount of overlap when inertial supercharging is not performed” according to the invention.

  Here, the reference time will be described with reference to FIG. FIG. 4 is a timing chart showing one operation timing of the intake valve 207 and the impulse valve 224 in each cylinder of the engine 200.

  In FIG. 4, the vertical axis represents the first cylinder, the second cylinder, the third cylinder, the fourth cylinder, and the impulse valve 224 in order from the upper stage, and the horizontal axis represents a common crank angle (that is, a kind of cylinder). Is the concept of time). In FIG. 4, the crank angle 0 ° is a reference value of the crank angle set for convenience, and in FIG. 4, it is set to the compression TDC of the first cylinder. Further, as apparent from FIG. 4, in the engine 200 which is an in-line four-cylinder engine, the order of the first cylinder → the third cylinder → the fourth cylinder → the second cylinder is performed (the engine operation process is repeatedly executed). Therefore, the configuration is such that only one stroke (for example, the intake stroke) is reached.

  Here, the reference valve opening timing forming a part of the reference valve opening side of the intake valve 207 in each cylinder 202 is a timing corresponding to the illustrated white circle m1 or the white circle m3 for the first cylinder, and illustrated for the second cylinder. It is a time corresponding to the white circle m5, a time corresponding to the illustrated white circle m7 for the third cylinder, and a time corresponding to the illustrated white circle m9 for the fourth cylinder. Similarly, the reference valve closing timing which forms a part of the valve closing side of the reference timing is a timing corresponding to the illustrated white circle m2 for the first cylinder, and a timing corresponding to the illustrated white circles m4 and m6 for the second cylinder. The third cylinder is a time corresponding to the illustrated white circle m8, and the fourth cylinder is a time corresponding to the illustrated white circle m10. In the following description, the white circle mx (x is a natural number) is appropriately substituted as the crank angle value.

  In a state where the opening / closing timing of the intake valve 207 is controlled to the reference timing, the difference between the opening timing of the first cylinder and the closing timing of the second cylinder (ie, “m4− m1 "and" m6-m3 "), the difference between the opening timing of the second cylinder and the closing timing of the fourth cylinder (ie," m10-m5 "), the opening timing of the third cylinder and the first cylinder Intake over corresponding to the difference between the valve closing timing (ie, “m2−m7”) and the difference between the valve opening timing of the fourth cylinder and the valve closing timing of the third cylinder (ie, “m8−m9”). Wrapping occurs.

  On the other hand, when the impulse valve 224 opens in the middle of the intake stroke and closes with the intake BDC (illustrated in the bottom of the vertical axis in the figure, the impulse valve 224 is not fully open except for the impulse charge region. If the impulse charge is executed while the opening / closing timing of the intake valve 207 is set to the reference timing (even if the reference timing itself is variable, no correction is made to the opening / closing timing at least before and after the execution of the impulse charge). And, at the end of the intake stroke in each cylinder, a period occurs in which the impulse valve 224 is closed and the intake valve 207 is opened (ie, m4-180, m2-360, m8-540, m10-720, And a period corresponding to m6-900). For this reason, the intake air blows back from the intake valve 207 as the piston rises during this period, and the intake charging efficiency in the cylinder 202 decreases. Originally, if the impulse valve 224 is closed, the communication pipe 206 becomes a closed space. However, this type of intake air cannot be trapped inside the communication pipe 206 due to the intake overlap described above. It will occur to the extent that it cannot be overlooked in practice. In addition, in this overlap period, the intake valve 207 is opened for the two cylinders whose intake strokes come in before and after the time series upper phase, so that the effect of the original impulse charge is likely to be reduced.

  Therefore, in the engine system 10 according to the present embodiment, in the impulse charge region, the opening / closing timing of the intake valve 207 is set to the opening / closing timing for impulse charging, and the impulse charging accompanied by the change of the intake overlap amount is executed. Here, the opening / closing timing for impulse charge will be described with reference to FIG. FIG. 5 is a timing chart showing other operation timings of the intake valve 207 and the impulse valve 224 in each cylinder of the engine 200. In the figure, the same reference numerals are given to the same portions as those in FIG. 4, and the description thereof will be omitted as appropriate.

  FIG. 5 shows the opening / closing timing of the intake valve 207 and the opening / closing timing of the impulse valve 224 in the case where the engine speed Ne takes one value corresponding to the impulse charge region described above. In FIG. 5, as apparent from comparison with FIG. 4, the valve opening timing of the intake valve 207 is retarded with respect to the reference timing. In the present embodiment, at the opening / closing timing for impulse charge, the opening timing of the intake valve 207 is substantially fixed near the intake TDC. That is, the valve opening timings are m1, m3, m5, m7 and m9, while m11 (m11> m1), m13 (m13> m3), m15 (m15> m5), m17 (m17), respectively. > M7) and m19 (m19> m9). On the other hand, when impulse charging is performed, the closing timing of the intake valve 207 is advanced with respect to the reference timing. FIG. 5 illustrates a state where the closing timing of the intake valve 207 is the intake BDC at the opening / closing timing for impulse charge. That is, in FIG. 5, the closing timing of the intake valve 207 is m12 (m12 <m2), m14 (m14 <m4), m16 (m4 (m12 <m2), while the reference timings are m2, m4, m6, m8 and m10, respectively. m16 <m6), m18 (m18 <m8) and m20 (m20 <m10). It is assumed that the opening / closing timing of the impulse valve 224 is the same as that in FIG.

  As described above, in the present embodiment, the opening / closing timing of the intake valve 207 when the impulse charge is performed is the valve opening timing delayed and the valve closing timing advanced with respect to the reference timing. That is, the operating angle is reduced more than the operating angle corresponding to the reference time. More specifically, the valve closing timing of the intake valve 207 is advanced by the phase variable function of the variable operating angle VVT 226, and the valve opening timing (that is, the phase of the valve) that is similarly advanced by the advance of this valve closing timing. In the case of the change alone, the valve opening timing is similarly advanced and overlapped with the valve opening period of the exhaust valve, and the introduction of fresh air is inhibited by the internal EGR). The working angle is changed. As a result, the intake overlap amount is reduced as compared with a case where this kind of opening / closing timing is not changed (in FIG. 5, it is almost zero), and the intake air blowback and the other cylinders of the intake air at the end of the intake stroke. Inflow to the air is suppressed, and it is possible to improve the charging efficiency of the intake air.

  The control of the opening / closing timing of the intake valve 207 according to the present embodiment is generally performed as described above. More specifically, the opening / closing timing of the intake valve 207 and the opening / closing timing of the impulse valve 224 are determined by the engine speed. It is variably controlled according to Ne. That is, returning to FIG. 2, when the acquired operating condition corresponds to the impulse charge region (step S102: YES), the ECU 100 calculates the impulse valve opening timing impop which is the valve opening timing (crank angle) of the impulse valve 224. (Step S103) Further, an impulse valve closing timing impcl which is a valve closing timing (crank angle) of the impulse valve 224 is calculated (Step S104).

  Here, the relationship between the opening / closing timing of the impulse valve 224 and the engine rotational speed Ne will be described with reference to FIG. FIG. 6 is a schematic diagram illustrating the characteristics of the opening / closing timing of the impulse valve 224. FIG. 6 is a diagram corresponding to the intake stroke of the third cylinder (that is, the intake TDC is 360 ° CA).

  In FIG. 6, the vertical axis and the horizontal axis represent the crank angle and the engine rotational speed Ne, respectively. Here, when the characteristic of the valve opening timing impop of the impulse valve 224 with respect to the engine rotational speed Ne is expressed as illustrated PRF_impop (see solid line), as illustrated, the valve opening timing impop is decreased on the increase side of the engine rotational speed Ne. It is set as a value that changes to the (advance side). This is because the arrival of the positive pressure wave (pulsation wave) of the intake air related to the impulse charge is delayed toward the higher rotation side. By correcting the valve opening timing to the advance side, the intake charge efficiency by the impulse charge is improved. The reduction of the effect is prevented as much as possible.

  On the other hand, when the characteristic of the valve closing timing impcl of the impulse valve 224 with respect to the engine rotational speed Ne is expressed as illustrated PRF_impcl (see the solid line), as shown in the figure, the valve closing timing impcl increases with respect to the increase of the engine rotational speed Ne ( That is, it is set as a value that changes to the retard side. This is because, as with the valve opening timing described above, the arrival of the positive pressure wave on the higher rotation side is delayed, so that the peak of the positive pressure wave is reached during the intake stroke by correcting the valve closing timing to the retard side. Thus, a decrease in the effect related to the improvement of the intake charging efficiency is prevented as much as possible.

  The ECU 100 holds in advance a map in which the open / close characteristics of the impulse valve 224 shown in FIG. 6 are numerically stored in the ROM. In the processing related to steps S103 and S104 in FIG. By selectively acquiring the values, the valve opening timing impop and the valve closing timing impcl of the impulse valve 224 are set. Note that the “calculation” according to the present embodiment is a concept that suitably includes an aspect in which one value is selectively acquired based on the previously defined relationship.

  In FIG. 6, the valve opening timing intop and the valve closing timing intcl of the intake valve 207 are represented as illustrated PRF_intop (see broken line) and illustrated PRF_intcl (see broken line), respectively. As shown in the drawing and as already described, the opening timing intotop of the intake valve 207 is substantially unchanged with respect to the engine rotational speed Ne, and is maintained in the vicinity of the intake TDC (here, 360 ° CA). On the other hand, the valve closing timing intcl is set as a value that changes to the increasing side (that is, the retarding side) with respect to the increase in the engine speed Ne. This is to synchronize the closing timing intcl of the intake valve 207 with the closing timing impcl of the impulse valve 224 described above, and as the closing timing impcl shifts to the retard side, the effect of the impulse charge is reduced. The valve closing timing intcl is also corrected to the retard side to ensure it.

  Returning to FIG. 2, when the valve opening timing impop and the valve closing timing impcl of the impulse valve 224 are set, the ECU 100 calculates an intake cam advance angle A which is an advance angle of the intake cam 207 (step S105).

  Here, the relationship between the intake cam advance angle A and the engine rotational speed Ne will be described with reference to FIG. FIG. 7 is a schematic diagram showing the characteristics of the intake cam advance amount A.

  In FIG. 7, the vertical axis and the horizontal axis represent the intake cam advance amount A and the engine rotational speed Ne, respectively. Note that the intake cam advance amount A corresponds to the retard side in the upward direction, and corresponds to the advance side in the downward direction.

  In FIG. 7, the characteristic of the intake cam advance amount A with respect to the engine rotational speed Ne is represented as PRF_A (see solid line) in the figure. Here, the intake cam advance amount A corresponding to the minimum rotational speed NeL is A0, which is a value corresponding to the difference between the valve closing timing of the intake valve 207 corresponding to the reference timing and the intake BDC. The intake cam advance amount A0 is an advance amount for setting the closing timing intcl of the intake valve 207 to the intake BDC. As shown in the figure, the intake cam advance amount A is set as a value that changes to the retard side as the engine rotational speed Ne rises within the impulse charge region. As already described, this is because the arrival of the peak of the positive pressure wave of the pulsation is relatively delayed as the engine rotational speed Ne increases, and the intake cam advance amount A defines the upper limit of the impulse charge region. A1 is taken at the reference value Neth. In addition, even when the intake cam advance amount A is shifted to the retard side with respect to A0 and is finally set to A1, the valve closing timing is advanced with respect to the valve closing timing corresponding to the reference timing. Is in a state.

  Returning to FIG. 2, when the intake cam advance angle amount A is calculated, the ECU 100 further calculates the intake cam working angle B (step S106). Here, the relationship between the intake cam working angle B and the engine rotational speed Ne will be described with reference to FIG. FIG. 8 is a schematic diagram showing the characteristics of the intake cam working angle B. FIG.

  In FIG. 8, the intake cam working angle B and the engine rotational speed Ne are represented on the vertical axis and the horizontal axis, respectively. Note that the intake cam operating angle B corresponds to the increasing side in the upward direction and corresponds to the decreasing side in the downward direction.

  In FIG. 8, the characteristic of the intake cam working angle B with respect to the engine rotational speed Ne is represented as illustrated PRF_B (see solid line). Here, the intake cam operating angle B corresponding to the minimum rotational speed NeL is B0, which is the closing timing of the intake valve 207 set as the intake BDC and the intake valve 207 of the intake valve 207 set almost at the intake TDC. This corresponds to the difference from the valve opening timing, that is, a value corresponding to approximately 180 ° CA. As shown in the figure, the intake cam working angle B is set as a value that changes to the increasing side as the engine speed Ne rises within the impulse charge region. As already described, this is because the valve opening timing intotop of the intake valve 207 is substantially unchanged, whereas the valve closing timing intcl of the intake valve 207 is retarded from the intake BDC as the engine rotational speed Ne increases. Therefore, the intake cam working angle B takes B1 at the reference value Neth that defines the upper limit of the impulse charge region.

  Note that the ECU 100 holds in advance a map in which the characteristics shown in FIGS. 7 and 8 are digitized in the ROM. In the processing related to steps S105 and S106 in FIG. By selectively acquiring, the intake cam advance angle amount A and the intake cam working angle B are set.

  When the opening / closing timing of the impulse valve 224, the intake cam advance angle amount A, and the intake cam working angle B are calculated, the ECU 100 executes intake valve drive control based on these (step S107) and executes the impulse valve drive control. (Step S108). That is, for the intake valve 207, the intake cam advance amount A and the intake cam action so that the valve opening timing intop is a value near the intake TDC and the valve closing timing intcl is a value corresponding to the engine rotational speed at that time. Based on the angle B, the operating angle variable type VVT 226 is driven and controlled. On the other hand, for the impulse valve 224, the actuator 225 is driven and controlled so that the valve opening timing impop and the valve closing timing impcl become values corresponding to the engine rotation speed at that time.

If the process which concerns on step S108 is performed, a process will be returned to step S101 and a series of processes will be repeated. The valve drive control is executed in this way. As a result, as already shown as an example in FIG. 5, the intake overlap amount is reduced when the impulse charge is executed, the reduction of the intake charge efficiency is suppressed, and the intake charge efficiency is relatively improved. . At this time, the opening / closing timing of the impulse valve 224 and the intake valve 207 is appropriately changed according to the engine rotational speed Ne, so that the effect of improving the charging efficiency of the intake air by the impulse charge is theoretically, substantially or realistically. Optimized under various constraints. Therefore, according to the present embodiment, it is possible to efficiently and effectively improve intake charging efficiency in each of the plurality of cylinders.
Second Embodiment
In the first embodiment described above, the opening timing intotop of the intake valve 207 in the impulse charge region is substantially fixed to the intake TDC. On the other hand, the closing timing intcl of the intake valve 207 gradually shifts from the intake BDC to the retard side in accordance with the engine rotational speed Ne. Therefore, at the opening / closing timing of the intake valve 207 according to the first embodiment, the intake valve overlap amount tends to increase, particularly in the high speed region, although there is naturally an effect of improving the charging efficiency of the intake with respect to the reference timing. And there is a possibility that the filling of the intake air by the impulse charge is somewhat hindered.

  A second embodiment of the present invention that can deal with such a problem will be described with reference to FIG. FIG. 9 is a timing chart showing still another operation timing of the intake valve 207 and the impulse valve 224 in each cylinder of the engine 200. In the figure, the same reference numerals are assigned to the same parts as those in FIG. 5, and the description thereof is omitted as appropriate.

  In FIG. 9, the opening / closing timing of the intake valve 207 and the opening / closing timing of the impulse valve 224 are shown when the engine rotation speed Ne takes one value corresponding to the impulse charge region described above. In FIG. 9, the closing timing intcl (m22, m24, m26, m28 and m30 in the drawing) of the intake valve 207 is slightly retarded with respect to the intake BDC. On the other hand, in the present embodiment, the opening timing intop of the intake valve 207 in one cylinder 202 is different from that in the first embodiment, and other cylinders 202 that have reached the intake stroke immediately before in time series (that is, the one cylinder If the cylinder is a first, second, third or fourth cylinder, the second, fourth, first and third cylinders) are retarded in synchronism with the retarded valve closing timing. The That is, the valve opening timings intop are m21, m23, m25, m27, and m29 shown in the drawing, and coincide with m24, m26, m30, m22, and m28, which are the valve closing timings of the other cylinders that have just reached the intake stroke.

  For this reason, in this embodiment, even if the closing timing intcl of the intake valve 207 is retarded in accordance with the change in the engine speed Ne, the intake overlap amount can be ideally always maintained at zero. . The intake overlap amount can be clearly reduced as compared with the case where at least the valve opening timing intop is fixed to the intake TDC. Therefore, the charging efficiency of intake air can be further improved.

  On the other hand, in order to generate a negative pressure in the communication pipe 206 in order to generate the pulsation of the intake air related to the impulse charge, the intake valve 207 must be opened during the closing period of the impulse valve 224. In other words, if the opening timing of the impulse valve 224 is advanced, it means that the opening timing of the intake valve 207 is relatively free. Therefore, the opening timing intop of the intake valve 207 does not necessarily coincide with the closing timing intcl of the intake valve 207 in the other cylinder that has just reached the intake stroke, and more specifically, the intake valve of the other cylinder. It suffices if it exists within a range that is retarded from the valve closing timing intcl of 207 and advanced from the valve opening timing impop of the impulse valve 224. This range corresponds to the hatching area shown in the figure, and as long as the opening timing intop of the intake valve 207 is set in this hatching area, at least some effect of the charging efficiency of the intake air by the impulse charge can be obtained. .

  Here, the intake valve 207 may be slightly opened due to the influence of the buffer portion of the intake cam 209 on the advance side of the original valve opening timing. Strictly speaking, the charging efficiency of the intake air can be somewhat lowered since intake air overlap occurs with other cylinders even when this type of valve is opened. In view of this, the valve opening timing intop of the intake valve 207 may be set on the retard side rather than being coincident with the valve closing timing intcl of the other cylinders as shown. In other words, by retarding the valve opening timing intop with respect to the valve closing timing intcl of the other cylinders, it is possible to eliminate the influence of this type of buffer and make the intake overlap amount closer to zero.

  Here, the characteristics of the valve opening timing intop of the intake valve 207 will be described with reference to FIG. FIG. 10 is a schematic diagram showing the opening timing of the intake valve 207 in the third cylinder. In FIG. 10, the same parts as those in FIG. 6 are denoted by the same reference numerals, and the description thereof is omitted as appropriate.

In FIG. 10, the characteristic of the closing timing of the intake valve 207 in the first cylinder that has reached the intake stroke immediately before the third cylinder is represented as PRF_intcl ′ (see the broken line) in the figure. The opening timing intop of the intake valve 207 in the present embodiment is exemplified as illustrated PRF_intop (see the broken line in the drawing), and the opening timing impop of the impulse valve 224 and the intake valve 207 of the immediately preceding cylinder (here, the first cylinder) are illustrated. It is set within the hatched area in the figure sandwiched between the valve closing timing intcl. By setting the valve opening timing intop of the intake valve 207 within this hatching region, in the second embodiment, the occurrence of intake overlap is suppressed regardless of the change in the engine speed Ne in the impulse charge region. The intake charging efficiency can be improved efficiently and effectively.
<Third Embodiment>
According to each of the above embodiments, the effect of improving the charging efficiency of intake air is ensured during the execution period of the impulse charge. However, as described above, the impulse charge is only executed in a part of the driving condition of the vehicle, and in fact, the impulse charge is likely to be appropriately switched between execution and non-execution. .

  Here, there is a significant difference between the changing speed of the opening / closing timing of the intake valve 207 by the variable working angle type VVT 226 and the opening / closing speed of the impulse valve 224, and the former tends to be slow in terms of the system configuration. In particular, the variable operating angle type VVT 226 uses a hydraulic actuator for the phase variable mechanism, and thus the tendency is strong.

  On the other hand, the opening / closing timing of the intake valve 207 optimized for impulse charging can naturally lead to lower engine output and lower combustion performance when the impulse charging is not performed than the reference timing. Therefore, the valve drive control according to the third embodiment of the present invention that can prevent the deterioration of the power performance, environmental performance, and economic performance of the vehicle during such a transition period will be described.

  First, with reference to FIG. 11, the operation timing of each valve when the impulse charge being executed is stopped will be described. FIG. 11 is a timing chart for explaining the operation timing of each valve in the transition period when the impulse charge is stopped. In the figure, the same reference numerals are given to the same parts as those in FIG. 6, and the description thereof will be omitted as appropriate.

  In FIG. 11, the horizontal axis represents the passage of time, and the vertical axis represents the state of the impulse charge permission flag Fg_imp1, the state of the impulse charge execution flag Fg_imp2, and the crank angle in order from the top. The impulse charge permission flag Fg_imp1 is turned on when the vehicle operating conditions (that is, the accelerator opening degree Ta and the engine rotational speed Ne) correspond to the previously described impulse charge region, and turned off when not applicable. The flag to be set. Further, the impulse charge execution flag Fg_imp2 is set to ON when the drive control of the impulse valve 224 for actually executing the impulse charge is performed, and when the impulse valve 224 is fully opened and fixed (that is, the impulse charge is stopped). These flags are respectively set to the OFF state.

  In FIG. 11, it is assumed that the impulse charge has been executed before time T1 (that is, both flags are in the ON state), and the impulse charge permission flag Fg_imp1 has changed to the OFF state at time T1. In this case, the ECU 100 starts driving control of the variable operating angle VVT 226 in order to return the opening / closing timing of the intake valve 207 to the reference timing described above. As a result, the valve opening timing intop (see PRF_intop in the drawing) of the intake valve 207 is gradually advanced from the value at the time of impulse charge execution (that is, the value on the retard side from the intake TDC (here, 360 ° CA)). At time T2, the value changes to a value corresponding to the reference time (that is, a value on the advance side with respect to the intake TDC). Similarly, the closing timing intcl of the intake valve 207 (see PRF_intcl in the drawing) is also gradually retarded from the value at the time of impulse charge execution (ie, the value near the intake BDC (here, 540 ° CA)) It changes to a value corresponding to the reference time at T2 (that is, a value that is retarded from the intake BDC), that is, from the time when the return control of the reference time by the variable working angle VVT 226 is started, the intake valve 207 is actually set. The transition period Ttrans corresponding to “T2−T1” is required until the opening / closing timing of the return to the reference time.

  On the other hand, since the opening / closing speed of the impulse valve 224 is faster than the changing speed of the opening / closing timing of the intake valve 207, the ECU 100 sets the impulse charge execution flag Fg_imp2 to the OFF state in conjunction with the impulse charge permission flag Fg_imp1 at time T1. When set, the impulse valve 224 can be controlled to the fully open fixed state in a short time that can be ignored in practice for the above-described transition period Ttrans.

  However, in this case, although the impulse charge is stopped, the opening / closing timing of the intake valve 207 is deviated from the reference timing which is the optimum value, and various problems such as a decrease in the output torque of the engine 200, a deterioration in the emission, and a deterioration in the fuel consumption. Problems can arise, apart from their magnitude.

  Therefore, the ECU 100 maintains the impulse charge execution flag Fg_imp2 in the ON state during the transition period Ttrans, and gradually changes the valve opening timing impop and the valve closing timing impcl of the impulse valve 224 during the transition period Ttrans described above. . In this way, the valve opening timing impop of the impulse valve 224 gradually shifts to the advance side at the time T1, and the valve closing timing impcl gradually shifts to the retarding side at the time T1. That is, the valve opening period of the impulse valve 224 gradually increases.

  As a result, the pulsation effect of the intake air by the impulse valve 224 gradually weakens during this transition period Ttrans, and the opening / closing timing of the intake valve 207 gradually approaches the optimum value accordingly. As a result, the output torque is continuously connected, so that the power performance of the vehicle when the impulse charge is stopped, the deterioration of the emission, and the deterioration of the fuel consumption are prevented.

  Next, with reference to FIG. 12, the operation timing of each valve in the transition period when the impulse charge is executed will be described. FIG. 12 is a timing chart for explaining the operation timing of each valve when the impulse charge is executed. In the figure, the same reference numerals are given to the same portions as those in FIG. 11, and the description thereof will be omitted as appropriate.

  In FIG. 12, it is assumed that the impulse charge is stopped before time T3 (that is, both flags are in the OFF state), and the impulse charge permission flag Fg_imp1 is changed to the ON state at time T3.

  Here, as described above, the opening / closing speed of the impulse valve 224 is faster than the changing speed of the opening / closing timing of the intake valve 207, but when the control for the variable operating angle VVT 226 is performed prior to the control for the impulse valve 224, As described above, there may be a practical disadvantage due to a deviation from the opening / closing timing of the intake valve 207 even though the impulse charge is not executed.

  Therefore, when the impulse charge permission flag Fg_imp1 is set to the ON state, the ECU 100 simultaneously sets the impulse charge execution flag Fg_imp2 to the ON state (of course, in the present embodiment, all are processes performed by the ECU 100), and promptly. At the same time, the opening / closing control of the impulse valve 224 is started.

  In contrast, the control for the intake valve 207 is started at a time T4 when a predetermined delay period Tdly has elapsed from the time T3 when the impulse charge execution flag Fg_imp2 (there is no substantial difference even with Fg_imp1) is set to the ON state. The As a result, the impulse charge is already executed at the time when the opening / closing timing of the intake valve 207 starts to change from the reference time, and it is possible to prevent the occurrence of various problems such as power performance degradation.

  On the other hand, as the impulse charge is started at time T3, the opening / closing timing of the impulse valve 224 is instantaneously changed to a predetermined opening / closing timing (that is, an opening / closing timing in which the peak of pulsation is synchronized with the closing timing of the intake valve 207). At that time, the output torque changes more or less easily, and the driver easily perceives the deterioration of drivability.

  Therefore, the ECU 100 determines the transition period Ttrans from time T4 to time T5 when the opening / closing timing of the intake valve 207 shifts to the opening / closing timing for impulse charge (although the meaning is different from the above-described Ttrans, the working angle variable type VVT226 is changed). As for the point of operation delay, it is the same quality), and the opening / closing timing of the impulse valve 224, mainly the valve opening timing impop, is gradually retarded until a predetermined valve opening timing. As a result, the output torque of the engine 200 when impulse charging is started is continuously connected, and drivability can be prevented from deteriorating.

  As described above, according to the present embodiment, by defining the priority order between the impulse valve 224 and the intake valve 207 in the transition period in which the execution state of the impulse charge is switched, the operation of the variable working angle VVT 226 is further improved. By continuously correcting the opening / closing timing of the impulse valve 224 for the transition period Ttrans resulting from the delay (that is, in the present embodiment, the ECU 100 also functions as an example of the “correction means” according to the present invention), It is possible to prevent a decrease in power performance, environmental performance, and economic performance of the vehicle during the transition period, and to more effectively enjoy the practical benefit according to the present invention that improves the charging efficiency of intake air. Is possible.

  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.

1 is a schematic configuration diagram conceptually showing a configuration of an engine system according to a first embodiment of the present invention. It is a flowchart of the valve drive control performed by ECU in the engine system of FIG. It is a schematic diagram of an impulse charge area. 2 is a timing chart showing one operation timing of an intake valve and an impulse valve in each cylinder of the engine provided in the engine system of FIG. 1. 6 is a timing chart showing other operation timings of an intake valve and an impulse valve in each cylinder of the engine provided in the engine system of FIG. 1. It is a schematic diagram which illustrates the characteristic of the opening / closing timing of the impulse valve set in the valve drive control of FIG. FIG. 3 is a schematic diagram illustrating characteristics of an intake cam advance amount set in the valve drive control of FIG. 2. FIG. 3 is a schematic diagram illustrating characteristics of an intake cam working angle set in the valve drive control of FIG. 2. FIG. 10 is a timing chart illustrating still another operation timing of the intake valve and the impulse valve in each cylinder of the engine included in the engine system of FIG. 1 according to the second embodiment of the present invention. FIG. 6 is a schematic diagram illustrating the opening timing of an intake valve in a third cylinder according to a second embodiment of the present invention. It is a timing chart explaining the operation timing of each valve in the case of stopping the impulse charge according to the third embodiment of the present invention. It is a timing chart explaining the operation | movement timing of each valve in the case of performing impulse charge concerning 3rd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Engine system, 100 ... ECU, 200 ... Engine, 202 ... Cylinder, 204 ... Intake pipe, 205 ... Throttle valve, 206 ... Communication pipe, 207 ... Intake valve, 216 ... Turbine, 218 ... Compressor, 222 ... Intercooler, 223 ... Surge tank, 224 ... Impulse valve, 225 ... Actuator, 226 ... Variable working angle VVT.

Claims (3)

Each of the plurality of cylinders provided in the vehicle, a plurality of cylinders, an intake passage shared among the plurality of cylinders, an intake control valve installed in the intake passage and capable of generating an intake pulsation according to an open / closed state, and the plurality of cylinders An intake control device for an internal combustion engine comprising variable valve operating means capable of changing the opening and closing timing of the intake valve in
First control means for controlling the intake control valve so that inertia supercharging by pulsation of the intake air is performed according to driving conditions of the vehicle;
When the inertial supercharging is performed, the overlap amount of the valve opening period of the intake valves between the respective ones is smaller than the overlap amount when the inertial supercharging is not performed. Second control means for controlling the variable valve means ,
The first control means controls the intake control valve so that the inertial supercharging stops when the inertial supercharging should be stopped,
Before the intake control valve is controlled to stop the inertia supercharging, the second control means adopts the opening / closing timing of each intake valve in advance when the inertia supercharging is not executed. Controlling the variable valve actuating means so as to return to a predetermined reference time determined to be
When the inertial supercharging is to be executed, the first control unit is configured to perform the inertial supercharging before the variable valve means is controlled to reduce the overlap amount. Control the control valve
An intake air control apparatus for an internal combustion engine. The second control means is configured such that the opening timing of the intake valve in the other cylinder for the one cylinder and the other cylinder that reach the intake stroke before and after the time series upper phase is the intake valve in the one cylinder. The intake control device for an internal combustion engine according to claim 1, wherein the variable valve operating means is controlled so as to synchronize with the valve closing timing. And a correction means for correcting the opening / closing timing of the intake control valve in accordance with the amount of change in the opening / closing timing of the intake valve in each of the steps. Item 3. The intake control device for an internal combustion engine according to Item 1 or 2 .

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