JP2006258078A - Control device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten time from start of stopping of an engine to getting capable of restarting in economy running control such as idling stop. <P>SOLUTION: A control device for an engine relating to an embodiment of this invention is provided with an intake air control valve capable of closing an inside of an intake passage and capable of opening and closing with synchronizing with opening and closing an intake valve, and a stop control means executing engine stop control when a predetermined stop condition is established, and includes control of the intake control valve to limit intake air quantity to the engine. The intake control valve instead of an intake throttle valve immediately limits intake air quantity from a time of engine stop request t0. Open valve control of the intake throttle valve as a preparatory control which was necessary at a time of engine stop becomes unnecessary, engine stop time is shortened, and time Δt3 from start t0 of engine stopping to getting capable of restarting can be shortened. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an engine control device, and more particularly to a vehicle engine control device capable of executing eco-run control for performing idling stop or the like.

  There is already known a technique for automatically stopping an engine that is idling under conditions such as waiting for a signal during driving of a vehicle to improve fuel efficiency (see, for example, Patent Document 1). In this case, when a predetermined restart operation is performed after the engine is automatically stopped, for example, when the throttle pedal is depressed, the engine is restarted and the vehicle can start.

JP 2003-65104 A

  In eco-run control typified by such idling stop, there is a demand for suppressing engine vibration when the engine is stopped. For this reason, preparatory control such as closing the intake throttle valve is performed between the time when the engine stop request is made and the time when fuel injection is stopped. In addition, when the engine is restarted, prior to the start of fuel injection, preparatory control such as opening the intake throttle valve is performed in order to ensure the amount of air at the time of startup.

  Since such preparatory control is involved, there is a problem that it is not possible to shorten the time from when the engine is stopped until it can be restarted. That is, in reality, there is a case where it is desired to restart immediately after the engine stop is started, and there is a demand for shortening the time required. In particular, there is a request to reduce the stop time from when the engine is requested to stop until the engine actually stops.

  Therefore, the present invention has been made in view of such circumstances, and an object of the present invention is to provide an engine control device capable of shortening the time from the start of engine stop until the engine can be restarted.

  In order to achieve the above object, an engine control apparatus according to an aspect of the present invention is provided in an intake passage upstream of an intake valve, can close the intake passage, and is synchronized with opening and closing of the intake valve. An intake control valve that can be opened and closed, and stop control means for executing a predetermined stop control for stopping the engine when a predetermined stop condition is satisfied, wherein the stop control restricts an intake amount to the engine. And controlling the intake control valve as described above.

  According to this configuration, since the intake control valve limits the intake air amount to the engine instead of the intake throttle valve, vibrations when the engine is stopped can be suppressed. At the same time, since the intake control valve can immediately limit the intake amount from when the engine is requested to stop, the intake amount can be limited immediately after the engine is requested to stop and fuel injection can be stopped. . As a result, the time required for the preparatory control can be omitted, the time from the start of the engine stop until the engine can be restarted can be shortened, and in particular, the time required for the engine stop can be shortened.

  From this point of view, preferably, the stop control includes stopping fuel injection to the engine, and the stop control means stops fuel injection at the same time as the predetermined stop condition is satisfied, and the intake control valve Start controlling.

  Preferably, the control device further includes a controllable intake throttle valve provided in an intake passage upstream of the intake control valve, and the stop control is performed when the intake throttle valve is at a predetermined opening on the valve closing side. And controlling the intake control valve so as to obtain a corresponding intake amount. As a result, the intake air amount when the engine is stopped is surely limited, which is suitable for suppressing vibration when the engine is stopped.

  The stop control may include controlling the intake control valve so that a sum of a pumping loss in the exhaust / intake stroke and a negative work in the compression / expansion stroke is maximized. Thereby, the engine stop time can be shortened.

  Preferably, the apparatus further comprises restart control means for executing a predetermined restart control for restarting the engine when a predetermined restart condition is satisfied after the start of the stop control. Controlling the intake control valve such that the intake air amount to the engine is increased.

  According to this configuration, since the intake air amount is increased by the intake control valve when the engine is restarted, there is a possibility that the intake air amount required for starting can be ensured even when the opening degree of the intake throttle valve is not sufficient. Thereby, the influence of the opening degree of the intake throttle valve at the time of restart can be reduced, and the time when restart is possible can be advanced.

  An engine control apparatus according to another aspect of the present invention is provided in an intake passage on the upstream side of an intake valve, and is capable of closing the intake passage and opening and closing in synchronization with opening and closing of the intake valve. A control valve, stop control means for executing a predetermined stop control for stopping the engine when a predetermined stop condition is satisfied, and restarting the engine when a predetermined restart condition is satisfied after the start of the stop control. Restart control means for executing a predetermined restart control for starting, and the restart control includes controlling the intake control valve so that an intake air amount to the engine is increased. And

  An engine control apparatus according to yet another embodiment of the present invention is provided in an intake passage upstream of an intake valve, and can close and close the intake passage in synchronization with opening and closing of the intake valve. An intake control valve and stop control means for executing a predetermined stop control for stopping the engine when a predetermined stop condition is satisfied, the stop control including a pumping loss in an exhaust / intake stroke, a compression / And controlling the intake control valve so as to maximize the sum of negative work in the expansion stroke.

  According to this configuration, the engine stop time can be shortened over a wide range of applications, not limited to eco-run control.

  The intake control valve is preferably capable of completely closing the intake passage.

  According to the present invention, an excellent effect of shortening the time from the start of engine stop until it can be restarted is exhibited.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 schematically shows a configuration of an engine control apparatus according to the present embodiment. In the present embodiment, the engine 1 is a vehicular multi-cylinder diesel engine (only one cylinder is shown in the figure), and fuel made of light oil is injected from the injector 10 into the combustion chamber 13 in the cylinder 12 and compressed by the piston 24. The structure is such that self-ignition occurs and exhaust gas is discharged through the exhaust passage 17. The present invention is not limited to a diesel engine, but can be applied to other types of engines such as gasoline engines, and can also be applied to engines using liquefied natural gas such as alcohol or LPG as fuel. However, in the case of a diesel engine, the vibration at the time of engine stop becomes a problem because the weight of the piston 24 is large. Therefore, the present invention is particularly effective for a diesel engine.

  As is known, the intake passage 11 is defined by an intake pipe, a surge tank, an intake manifold, and an intake port 15 connected to each other. In particular, the downstream end thereof is defined by the intake port 15, and the outlet of the intake port 15 is opened and closed by the intake valve 16. The injector 12 is provided facing the top of the combustion chamber 13 and injects fuel into the cavity 14 provided at the top of the piston 24. The injector 12 is supplied with high-pressure fuel from a common rail (not shown), and the pressure of the fuel, that is, injection pressure, is controlled by an electronic control unit (hereinafter referred to as ECU) 100 as control means according to the engine operating state. A glow plug may be provided facing the combustion chamber 13.

  As is known, the exhaust passage 17 is defined by an exhaust port 19, an exhaust manifold, an exhaust pipe and a catalyst 18 connected to each other. In particular, the upstream end is defined by the exhaust port 19, and the inlet of the exhaust port 19 is opened and closed by the exhaust valve 20. In the present embodiment, the intake valve 16 and the exhaust valve 20 are mechanically opened and closed by a camshaft (not shown) that is rotationally driven in synchronization with the engine 1. Accordingly, the valve opening timing and the valve opening period may be controlled. The catalyst 18 is provided in the middle of the exhaust pipe to remove harmful substances such as CO, HC, NOx, and DP (diesel particulates) in the exhaust gas.

  The intake passage 11 is provided with an air flow meter 21, an intake throttle valve 22, and an intake control valve 23 in order from the upstream side. The air flow meter 21 outputs a signal corresponding to the air flow rate passing through the ECU 100 to the ECU 100. The intake throttle valve 22 can be controlled. The intake control valve 23 will be described in detail later. Thus, in the intake passage 11, the intake control valve 23 is provided on the upstream side of the intake valve 16, and the intake throttle valve 22 is provided on the upstream side of the intake control valve 23.

  The engine 1 is also provided with an EGR device 40 for performing exhaust gas recirculation (EGR). The EGR device 40 includes an EGR passage 41 that connects the intake passage 11 and the exhaust passage 17, and an EGR valve 42 and an EGR cooler 43 that are provided in the EGR passage 41. The EGR passage 41 is for returning a part of the exhaust gas (EGR gas) in the exhaust passage 17 to the intake passage 11, and the EGR valve 42 is for adjusting the flow rate of the EGR gas. The EGR cooler 43 is for cooling the EGR gas. The downstream end of the EGR passage 41 is connected to the intake passage 11 on the downstream side of the intake throttle valve 22, and in this embodiment is connected to the intake passage 11 between the intake throttle valve 22 and the intake control valve 23. .

  The piston 24 is accommodated in the cylinder 12 so as to be able to reciprocate, and is connected to a crankshaft 26 via a connecting rod 25. A starter 27 for starting the engine is provided, which meshes with a ring gear provided at the end of the crankshaft 26 to drive the crankshaft 26 when the engine is started.

  The electrical configuration of the engine control apparatus will be described. In addition to the injector 10, the air flow meter 21, the intake throttle valve 22, the intake control valve 23, the EGR valve 42, and the starter 27, the ECU 100 includes a crank angle sensor 28, an accelerator opening sensor 30, a brake switch 31, and a vehicle speed sensor 32. Is connected.

  The injector 10 is opened and closed based on an on / off signal output from the ECU 100, thereby executing and stopping fuel injection. The intake throttle valve 22 is in the form of a butterfly valve, and detects the valve element 37 disposed in the intake passage 11, an electric actuator 38 such as a rotary solenoid that drives the valve element 37, and the opening degree of the valve element 37. Sensor 39. The opening degree of the intake throttle valve 22 is controlled by the ECU 100. At this time, the electric actuator 38 is controlled so that the actual opening detected by the sensor 39 matches the opening instruction value output from the ECU 100. The accelerator opening sensor 30 outputs to the ECU 100 a signal corresponding to the operation amount (depression amount) of the accelerator pedal by the driver. The starter 27 is turned on / off based on an on / off signal output from the ECU 100.

  The crank angle sensor 28 outputs a pulse signal to the ECU 100 at a predetermined phase interval of the crankshaft 26. Based on this pulse signal, the ECU 100 detects the phase of the crankshaft 26, that is, the engine 1, and calculates the rotational speed of the crankshaft 26, that is, the engine speed. The brake switch 31 outputs an on / off signal corresponding to the foot brake operation by the driver to the ECU 100. It is on when the brake is activated. The vehicle speed sensor 32 outputs a signal corresponding to the vehicle speed (vehicle speed) to the ECU 100.

  The ECU 100 controls the fuel injection amount and the fuel injection timing according to the engine operating state. That is, the ECU 100 mainly uses the engine rotation speed obtained by the crank angle sensor 28 and the accelerator opening obtained by the accelerator opening sensor 30 based on a map stored in advance, and the fuel injection amount and fuel in the injector 10. The injection timing is determined, and the injector 10 is controlled based on these values.

  The intake throttle valve 22 and the EGR valve 42 are controlled by the ECU 100 as follows. That is, when the EGR is not executed, the intake throttle valve 22 is fully opened and the EGR valve 42 is fully closed. On the other hand, when the EGR is executed, the opening is controlled so that the intake throttle valve 22 creates a pressure difference from the exhaust side to the intake side. Then, the EGR valve 42 is controlled to a predetermined opening so as to obtain an EGR flow rate corresponding to the engine operating state.

  The intake control valve 23 includes a valve body 33 disposed in the intake passage 11 and an electric actuator 34 such as a rotary solenoid that drives the valve body 33. In addition, you may further provide the sensor which detects the opening degree of the valve body 33. FIG. The intake control valve 23 can close the inside of the intake passage 11. In particular, in this embodiment, unlike the intake throttle valve 22, the intake passage 11 is completely closed when the valve is fully closed, and the passage of intake air is completely blocked. It has a highly sealed structure. On the other hand, the intake throttle valve 22 allows the intake air to pass only by restricting the intake passage 11 to the maximum when fully closed. Further, the electric actuator 34 of the intake control valve 23 can be operated at a much higher speed than the electric actuator of the intake throttle valve 22, has high responsiveness, and the valve element 33 is within 10 milliseconds, for example, within 10 msec. It can be opened and closed on the order of CA. Thereby, the intake control valve 23 can be opened and closed in synchronization with the opening and closing of the intake valve 16. In the present embodiment, the intake control valve 23 is in the form of a butterfly valve, but may be in another form such as a shutter valve.

  The opening degree of the intake control valve 23 is controlled from fully open to fully closed in accordance with an opening signal output from the ECU 100 to the electric actuator 34. The intake control valve 23 is provided for each cylinder. When each cylinder has a plurality of intake passages 11 (particularly, intake ports 15), the intake control valve 23 is provided for each intake passage 11. The plurality of intake control valves 26 thus provided can be individually controlled for each cylinder and each intake passage 11. In the present embodiment, the intake control valve 26 is controlled in units of individual cylinders.

  The intake control valve 23 in the present embodiment is used for performing so-called impulse supercharging during normal engine operation. An overview of this impulse supercharging is detailed in "Impulses for Greater Driving Fun", which was announced on September 9 by Siemens VDO Automotive AG at the 2003 Frankfurt Motor Show. This impulse supercharging is effective when it is necessary to rapidly accelerate the engine during overtaking or the like while the vehicle is running.

  In this case, the intake control valve 23 is controlled so as to be opened later than the intake valve 16 is opened, for example, to be opened later in the valve opening period of the intake valve 16. As a result, the intake passage 11 between the intake control valve 23 and the intake valve 16 (hereinafter referred to as an intervalve passage 35) between the opening start timing of the intake valve 16 and the opening start timing of the intake control valve 23. ), And thereafter, the intake control valve 23 is instantaneously opened, so that the intake air in the intake passage 11 located on the upstream side of the intake control valve 23 flows into the combustion chamber 13 all at once. A large amount of intake air can be filled into the combustion chamber 13 by the inertia supercharging effect. In other words, in the impulse supercharging, substantial supercharging is performed by using the differential pressure formed on the upstream and downstream sides of the intake control valve 23 and the inertia of the intake air. This supercharging is started simultaneously with the start of the control of the intake control valve 23 as described above, that is, started simultaneously with the depression of the accelerator pedal. It is suitable for eliminating the acceleration delay of the vehicle.

  By the way, in this embodiment, the eco-run control for reducing fuel consumption is performed as follows. Hereinafter, an idling stop will be described as an example of the eco-run control. In particular, the present embodiment is characterized in that the intake control valve 23 as described above is used during the eco-run control.

  First, as a comparative example, the eco-run control as a base when the intake control valve 23 is not used will be described with reference to FIG.

  In the figure, TH and Ne represent the opening degree of the intake throttle valve 22 and the engine speed (detected value), respectively. In the illustrated example, stop control for stopping the engine is executed from time t0, and then restart control for restarting the engine is executed from time t4. At time t0, when stop control is started when a predetermined condition described later is satisfied, the intake throttle valve 22 is set to a predetermined opening TH1 on the valve closing side (for example, fully closed, 1/5 opening, etc.). Controlled. This is for restricting the amount of intake air to the engine and suppressing vibration when the fuel injection is stopped later and the engine is rotated and reduced due to inertia. Particularly in a diesel engine, this vibration is likely to be a problem because compression is performed at a high pressure and the piston is relatively heavy. When the intake throttle valve 22 is closed in this manner, the amount of intake air in the combustion chamber 13 is reduced, so that the actual compression ratio is reduced, vibration is suppressed, and the engine can be stopped smoothly. At the same time as closing control of the intake throttle valve 22, valve closing control for fully closing the EGR valve 42 is also executed.

  Thus, at the same time that the intake throttle valve 22 reaches the predetermined opening TH1 (time t1), the fuel injection is stopped. As a result, the engine rotates coasting only by its inertia, and the rotation decreases. When the engine speed Ne becomes a value Ne1 near zero corresponding to immediately before the engine stops (time t2), the value Ne1 is maintained for a predetermined time Δt2 on the ECU side. This is because the crank angle sensor 28 generates a pulse signal at a predetermined phase interval of the crankshaft 26, and the ECU 100 cannot predict whether or not the final pulse signal will be output immediately before stopping (that is, the rotation stops). If this is the case, a pulse signal will not be output), and the rotation speed cannot be detected, and at the same time, stoppage of rotation cannot be determined. Therefore, the engine speed is detected by the crank angle sensor 28 only when the engine speed Ne is equal to or greater than the predetermined value Ne1, and when the engine speed Ne reaches the predetermined value Ne1, a predetermined period Δt2 has elapsed thereafter. It is determined that the engine is stopped at time t3.

  The stop control is terminated by this engine stop determination, and the control shifts to the restart control. From time t3, the intake throttle valve 22 is now controlled to open. This is to ensure the air amount at the next restart and to prevent smoke due to an insufficient air amount at the restart. Here, the intake throttle valve 22 is controlled to be fully opened. Then, at the same time that the intake throttle valve 22 reaches a predetermined opening TH2 that can ensure the minimum amount of air at the time of restart (time t4), the intake throttle valve 22 becomes in a restartable state and is allowed to restart. The illustrated example shows the case of the shortest time at which restart is immediately started at this time t4. At this restart, the starter 27 is turned on, the engine is restarted, and its rotation increases.

  As described above, the base control includes preliminary control such as closing and opening the intake throttle valve 22 in engine stop and restart control, which can be restarted from the start of engine stop (t0). This is an obstacle to shortening the time to the time (t4) (hereinafter referred to as the shortest restartable time).

  On the other hand, in the eco-run control of the present embodiment using the intake control valve 23, as shown in FIG. 3, at the time t0, the fuel injection is stopped and the engine rotation is reduced simultaneously with the start of the stop control. At the same time, opening control of the intake throttle valve 22 is started. This is possible because the intake control valve 23 is controlled so as to limit the amount of intake air into the engine instead of the intake throttle valve 22, and in particular, it corresponds to a predetermined opening TH1 of the intake throttle valve 22. This is because the intake air amount is controlled as described later. According to the present embodiment, since the intake control valve 23 can sufficiently limit the intake amount from t1 when the engine stop start request is made, the time Δt1 required for valve closing control of the intake throttle valve 22, that is, preliminary control. (Refer to FIG. 2) can be omitted, and the stop time and the shortest restartable time can be shortened. Further, as in the comparative example, the intake throttle valve 22 is not controlled once to the closing side and then to the opening side, but is controlled to the opening side simultaneously with the start of the stop control. The time and the shortest restartable time can be shortened. According to this embodiment, the shortest restartable time is significantly shorter (Δt3) than the comparative example. However, in the illustrated example, the actual restart is performed at time t4 after the engine is stopped.

  FIG. 4 is a flowchart showing a stop control procedure of the present embodiment. This flow is executed by the ECU 100 for each injection cycle. In the first step S101, the ECU 100 determines whether or not there is an engine stop request. That is, ECU 100 turns on the engine stop request signal when a predetermined stop condition is satisfied according to a program stored in advance. The ECU 100 determines that there is an engine stop request when this engine stop request signal is on, and determines that there is no engine stop request when the engine stop request signal is off, and ends this flow.

  The predetermined stop condition here means that, in the case of idling stop in the present embodiment, for example, the vehicle speed detected by the vehicle speed sensor 32 is zero and the brake switch 31 is on (that is, the foot brake is operated). ). This condition can be changed as appropriate. For example, conditions such as the detected engine speed being at a predetermined idling speed for a predetermined time or longer (that is, idling stable state) can be added, and conditions suitable for eco-runs other than idling stop It can also be changed.

  If the ECU 100 determines in step S101 that there is an engine stop request (step S101: YES), the ECU 100 proceeds to step S102, maintains the injector 10 off, and stops fuel injection. That is, the fuel injection is immediately stopped without executing the preliminary control including the valve closing control of the intake throttle valve 22 as in the comparative example in advance. Since step S101 and step S102 are executed in the same flow, they are executed at the same time in terms of time.

  Next, in step S103, the ECU 100 executes valve opening control for controlling the intake throttle valve 22 toward a target opening that is equal to or greater than the predetermined opening TH2. The target opening here is fully open, but can be set to any opening as long as it is at least equal to the predetermined opening TH2 or an opening on the open side. Thus, here, the valve opening control of the intake throttle valve 22 which is the preliminary control in the restart control of the comparative example is brought forward and included in the stop control.

  Next, the ECU 100 proceeds to step S104, executes opening / closing control of the intake control valve 23 as described later, and ends this flow. The opening / closing control of the intake control valve 23 is continuously performed until the stop control ends, that is, until the engine stop determination (t3 in FIG. 3). This is because the engine stop request signal is turned off in step S101 after this time, and it is determined that there is no engine stop request.

  After the engine is stopped, predetermined restart control is executed when a predetermined restart condition is satisfied. The restart condition is that (1) the opening degree of the intake throttle valve 22 is equal to or greater than the predetermined opening degree TH2, and (2) the output value of the accelerator opening degree sensor 30 is set to a predetermined threshold value by the accelerator depression operation of the driver. To meet all of the above. Note that instead of (2), (2 ′) the brake switch 31 may be turned off by the driver's foot brake release operation.

  As can be seen, the opening / closing control of the intake control valve 23 in the present embodiment is executed from when fuel injection is stopped until engine rotation is stopped. Such coasting rotation of the engine is usually about 5 to 10 rotations.

  Next, one mode of opening / closing control of the intake control valve 23 executed in step S104 will be described with reference to FIG. FIG. 5 shows valve opening periods of the intake valve 16 and the intake control valve 23, respectively. The opening timing and closing timing of the intake valve 16 are indicated by IN1 and IN2, respectively, and the opening timing and closing timing of the intake control valve 23 are indicated by IC1 and IC2, respectively. TDC and BDC are respectively a top dead center at which the intake stroke starts (intake top dead center) and a bottom dead center at which the compression stroke starts (compression bottom dead center).

  In this embodiment, the opening period of the intake control valve 23 is the intake amount corresponding to the intake throttle valve 22 at the predetermined opening TH1 on the valve closing side as described in the comparative example (FIG. 2). So that it is set. That is, it is a valve opening period that restricts the amount of intake air to the engine and suppresses vibration when the engine speed decreases after stopping fuel injection. In this aspect, the valve opening period of the intake control valve 23 is set to a relatively short period of the previous period of the valve opening period of the intake valve 16, but if the intake air amount to the engine can be limited as described above, The valve opening timing and the valve opening period can be arbitrarily set. According to the control of the intake control valve 23, the introduction of intake air is allowed only during the relatively short valve opening period, so that the intake air amount introduced into the combustion chamber 13 is limited instead of the intake throttle valve 22, and the engine Engine vibration during rotation reduction can be suppressed. In addition, since a pumping loss is caused by doing so, a quick stop of the engine can be promoted.

Next, another aspect of engine restart control will be described with reference to FIGS.
In this aspect, as shown in FIG. 6, only when the condition (2) “the output value of the accelerator opening sensor 30 exceeds a predetermined threshold” is satisfied while the engine rotation is decreasing after the fuel injection is stopped. Restart control is started. That is, the above condition (1) “the opening degree of the intake throttle valve 22 is equal to or greater than the predetermined opening degree TH2” is not included in the restart condition, and the reopening is performed even if the opening degree of the intake throttle valve 22 is less than the predetermined opening degree TH2. It can be started. The reason why this can be done is that the intake air amount is increased by the impulse supercharging by the intake control valve 23. In the illustrated example, during the valve opening control of the intake throttle valve 22, the restart control is started (t5) before the opening reaches the predetermined opening TH2 (t6), and the engine rotation that has been decreasing is reduced. Ascending and returning by self-driving according to normal control.

  As described above, according to the impulse supercharging, the intake air is supercharged and sent to the combustion chamber 13, so that it is possible to ensure the intake amount necessary for restart even if the opening of the intake throttle valve 22 is not sufficient. There is sex. Therefore, it becomes unnecessary to wait until the opening degree of the intake throttle valve 22 becomes sufficient, and it becomes possible to advance the time when the restart can be performed.

  A flowchart of the restart control in this case is shown in FIG. This flow is executed by the ECU 100 for each injection cycle. In first step S201, the ECU 100 determines whether or not there is an engine restart request. That is, the ECU 100 turns on the engine restart request signal when a predetermined restart condition, that is, the condition (2) (or (2 ′)) can be satisfied. The ECU 100 determines that there is an engine restart request when the engine restart request signal is on, and determines that there is no engine restart request when the engine restart request signal is off, and ends this flow. .

  If the ECU 100 determines in step S201 that there is an engine restart request (step S201: YES), the ECU 100 proceeds to step S202 and stops the stop control. As a result, the engine stop request signal is turned off, and fuel injection can be executed.

  Next, ECU 100 determines in step S203 whether or not the detected engine rotation speed is decreasing. If it is decreasing (step S203: YES), the process proceeds to step S204, the opening / closing control of the intake control valve 23 as described later is executed, and this flow is ended. On the other hand, when it is not decreasing (step S203: NO), this corresponds to the case where the engine has already stopped, and therefore, the process proceeds to step S205, the engine is restarted by the starter 27, and this flow is ended.

  A mode of opening / closing control of the intake control valve 23 executed in step S204 will be described based on FIG. Here, since impulse supercharging is executed and the intake air amount is positively increased, the valve opening period of the intake control valve 23 is different from the mode of FIG. That is, the valve opening period of the intake control valve 23 is set to the latter stage of the valve opening period of the intake valve 16. The valve opening timing IC1 of the intake control valve 23 is set to a timing slightly later than 90 ° ATDC in the present embodiment, but can be changed. The closing timing IC2 of the intake control valve 23 is set at the same time as or earlier than the closing time IN2 of the intake valve 16, and is the same time in this embodiment. In any case, the valve opening timing and the valve opening period of the intake valve 16 are set so that the intake amount can be increased sufficiently and sufficiently.

  Next, another aspect of the stop control will be described based on FIGS. Since this mode is different from the mode described with reference to FIGS. 3 to 5 only in the valve opening period of the intake control valve 23, the difference will be mainly described. The flowchart is the same as in FIG.

  FIG. 9 shows a valve opening period of the intake valve 16 and the intake control valve 23 in this embodiment. The valve opening period of the intake control valve 23 is set so that the intake air amount to the engine is limited as compared with the case where the intake throttle valve 22 and the intake control valve 23 are held fully open, as in the above-described aspect. At the same time, the intake air amount is set to be increased as compared with the case where impulse supercharging is executed and this is not executed. This is because the pumping loss in the exhaust / intake stroke is increased by limiting the intake air amount, and at the same time, the negative work in the compression / expansion stroke is increased by increasing the intake air amount, thereby reducing the negative work of the engine as a whole. The aim is to increase the stopping time and hence the shortest possible restart time.

  In this embodiment, the valve opening period of the intake control valve 23 is set to a relatively short period that is substantially the latter half of the valve opening period of the intake valve 16. The valve opening timing IC1 of the intake control valve 23 is set to a timing of approximately 90 ° ATDC. The closing timing IC2 of the intake control valve 23 is set before the closing timing IN2 of the intake valve 16. However, the valve opening period, valve opening timing, and valve closing timing of these intake valves 16 can be changed.

  The significance of this aspect will be described in more detail with reference to the PV diagrams of FIGS. FIG. 10 is a comparative example in the case where the opening / closing control of the intake control valve 23 as in this embodiment is not executed or the intake control valve 23 itself does not exist, and the intake air amount is optimized by optimization of the variable valve timing mechanism (VVT). This is an example of minimizing the above. A pumping loss in the exhaust / intake stroke is shown in region A, and a negative work in the compression / expansion stroke is shown in region B. According to this example, although a considerable amount of pumping loss is recognized, there is almost no negative work in the compression / expansion stroke.

  On the other hand, according to this aspect shown in FIG. 11, negative work can be increased while ensuring an equivalent pumping loss. That is, before the intake control valve 23 is opened, the piston 24 is lowered in a state where there is no inflow of air. Therefore, the combustion chamber 13 and the inter-valve passage 35 become negative pressure, which leads to an increase in pumping loss. On the other hand, when the intake control valve 23 is opened, the amount of in-cylinder air is increased by a short period of impulse supercharging, the compression work is increased by compressing the air, and heat loss is increased during the expansion stroke to increase the temperature and temperature. The pressure is further reduced and the negative work in the compression / expansion stroke is increased. Thus, the negative work performed by the engine as a whole increases, which makes it possible to stop the engine more quickly. Since the intake air amount to the engine is limited, vibration during engine stop can be suppressed.

As understood from this, the intake control valve 23 has the sum of the pumping loss in the exhaust / intake stroke and the negative work in the compression / expansion stroke (that is, the sum of the areas of the region A and the region B). It is preferably controlled to maximize. Further, in view of the fact that the engine stop time is shortened in this way, this aspect is applicable to any case where there is a request to shorten the engine stop time, and in that case, the present invention is not limited to the eco-run control. For example, this mode can also be applied to engine stop by a normal user. In this case, the stop condition is that the ignition switch is turned off.
The present invention can take various other embodiments. The eco-run control is not limited to idling stop, and may be a reduced-cylinder operation in which some of all cylinders are stopped. In this case, the present invention can be applied when the idle cylinder is stopped or restarted. The engine may be a supercharged type equipped with a turbocharger or the like.

  Embodiments of the present invention are not limited to the above-described embodiments, and all modifications, applications, and equivalents included in the spirit of the present invention defined by the claims are included in the present invention. Therefore, the present invention should not be construed as being limited, but can be applied to any other technique within the scope of the idea of the present invention.

1 is a system diagram schematically showing the configuration of an engine control device according to the present embodiment. It is a time chart which shows the eco-run control of a comparative example. It is a time chart which shows the eco-run control of this embodiment. It is a flowchart of stop control in this embodiment. It is a phase diagram which shows the valve opening period of the intake control valve in the stop control of this embodiment. It is a time chart which shows another aspect of restart control. It is a flowchart of another aspect of restart control. It is a phase diagram which shows the valve opening period of the intake control valve in another aspect of restart control. It is a phase diagram which shows the valve opening period of the intake control valve in another aspect of stop control. It is a PV diagram of a comparative example. It is a PV diagram of another mode of stop control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 11 Intake passage 15 Intake port 10 Injector 12 Cylinder 13 Combustion chamber 16 Intake valve 17 Exhaust passage 18 Catalyst 19 Exhaust port 20 Exhaust valve 22 Intake throttle valve 23 Intake control valve 27 Starter 33 Valve body 34 Actuator 35 Intervalve passage 31 Brake Switch 32 Vehicle speed sensor 100 Electronic control unit (ECU)

Claims (8)

An intake control valve provided in an intake passage on the upstream side of the intake valve, capable of closing the intake passage and opening and closing in synchronization with opening and closing of the intake valve;
A stop control means for executing a predetermined stop control for stopping the engine when a predetermined stop condition is satisfied,
The engine control apparatus according to claim 1, wherein the stop control includes controlling the intake control valve such that an intake air amount to the engine is limited.   The stop control includes stopping fuel injection to the engine, and the stop control means stops fuel injection simultaneously with the establishment of the predetermined stop condition and starts control of the intake control valve. The engine control apparatus according to claim 1, wherein   A controllable intake throttle valve provided in an intake passage on the upstream side of the intake control valve, and the stop control includes an intake air amount corresponding to when the intake throttle valve is at a predetermined opening on the valve closing side; The engine control device according to claim 1, further comprising controlling the intake control valve so as to become.   2. The stop control includes controlling the intake control valve so that a sum of a pumping loss in an exhaust / intake stroke and a negative work in a compression / expansion stroke is maximized. 2. The engine control device according to 2.   The engine further comprises restart control means for executing predetermined restart control for restarting the engine when a predetermined restart condition is satisfied after the start of the stop control, and the restart control includes an intake air amount to the engine. The engine control device according to any one of claims 1 to 4, further comprising controlling the intake control valve so as to be increased. An intake control valve provided in an intake passage on the upstream side of the intake valve, capable of closing the intake passage and opening and closing in synchronization with opening and closing of the intake valve;
Stop control means for executing predetermined stop control for stopping the engine when a predetermined stop condition is satisfied;
Restart control means for executing a predetermined restart control for restarting the engine when a predetermined restart condition is satisfied after the start of the stop control,
The engine control apparatus according to claim 1, wherein the restart control includes controlling the intake control valve such that an intake air amount to the engine is increased. An intake control valve provided in an intake passage on the upstream side of the intake valve, capable of closing the intake passage and opening and closing in synchronization with opening and closing of the intake valve;
A stop control means for executing a predetermined stop control for stopping the engine when a predetermined stop condition is satisfied,
The stop control includes controlling the intake control valve so that the sum of the pumping loss in the exhaust / intake stroke and the negative work in the compression / expansion stroke is maximized. . The engine control device according to any one of claims 1 to 7, wherein the intake control valve is capable of completely closing the intake passage.

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