JP6292199B2 - Multi-cylinder direct injection engine stop control device - Google Patents

Description

  The technology disclosed herein relates to a stop control device for a multi-cylinder direct injection engine.

  Patent Document 1 describes an automatic stop device according to a so-called idle stop technique in which an engine is automatically stopped when a predetermined condition is satisfied. This automatic stop device automatically stops the diesel engine. The closing timing of the intake valve is suitable for automatic start after the fuel cut to stop the fuel supply to the engine until the engine stops. The VVT is controlled so that the target closing timing is reached.

  Patent Document 2 describes that an HC trap filter is attached to an intake passage of an engine. The HC trap filter prevents the unburned fuel evaporative gas from being discharged outside the engine while the engine is stopped.

JP 2013-217696 A Japanese Patent Laid-Open No. 2006-37865

  By the way, the fuel adhering to the wall of the combustion chamber of the engine, the fuel coming out of the fuel injection valve due to oil leak, evaporates while the engine is stopped, and the evaporated gas is released to the atmosphere through the intake passage. Need to be prevented. As described in Patent Document 1, such an evaporation countermeasure is required not only when the engine is automatically stopped, but also when the engine is forcibly stopped according to the driver's intention.

  As described in Patent Document 2, it is effective to attach a filter to the intake passage in order to prevent evaporative gas from being released. However, simply attaching a filter to the intake passage has the disadvantage of greatly reducing the intake efficiency, as described in Patent Document 2. On the other hand, as described in Patent Document 2, a configuration in which the filter is retracted from the intake passage when the engine is operating and the intake passage is closed by the filter only when the engine is stopped is problematic. is there.

  The technology disclosed herein has been made in view of the above points, and the purpose of the technology is to ensure that fuel evaporative gas is released to the atmosphere through the intake passage while the engine is stopped. It is to prevent.

  The technology disclosed herein relates to a stop control device for a multi-cylinder direct injection engine. The apparatus includes: an engine having a plurality of cylinders; a fuel injection valve configured to inject fuel directly into each cylinder; and a lift in synchronization with the rotation of the crankshaft of the engine. An intake valve configured to open and close a connected intake port, a variable valve mechanism configured to change a valve opening period of the intake valve, and a fuel cut for stopping fuel supply to the engine by the fuel injection valve A stop control unit configured to perform stop control of the engine in a period from the start to the stop of the engine.

  And the said stop control part shortens the valve opening period of the said intake valve of each cylinder by the said variable valve mechanism so that the all intake valve closing period in which all the intake valves are closed is set. At the same time, the crank angle position when the engine is completely stopped is set within the all intake valve closing period.

  According to this configuration, the engine stop control is performed in the period from the start of fuel cut until the engine stops. The engine stop control may be performed by applying a rotational load to the engine using, for example, an auxiliary machine driven by the engine. Such an auxiliary machine may be a generator (including an alternator) or a compressor of an air conditioner. By applying a rotational load to the engine using the auxiliary machine, the engine can be completely stopped at a desired crank angle position.

  The stop control unit shortens the valve opening period of the intake valve by a variable valve mechanism as engine stop control. In the three-cylinder four-cycle engine, in a normal operation state, the period during which all the intake valves of all the cylinders are closed is negligible or substantially absent, and in a four-cycle engine having four or more cylinders, the normal operation state In this case, part of the valve opening periods of the intake valves overlap each other, and there is substantially no period during which all the intake valves are closed. Therefore, the stop control unit shortens the valve opening period of each intake valve. That is, the valve opening period of the intake valve is made shorter than the intake stroke period from the top dead center to the bottom dead center of the piston. By doing so, the entire intake valve closing period in which all the intake valves are closed is set.

  In addition, the stop control unit causes the crank angle position when the engine is completely stopped to be within the all intake valve closing period. In this way, all intake ports are closed by the intake valves while the engine is stopped. As a result, even if the fuel adhering to the wall surface in the cylinder or the fuel coming out of the fuel injection valve due to oil tight leakage evaporates while the engine is stopped, it is released to the atmosphere through the intake passage. Is prevented.

  The engine stop mentioned here is not limited to the so-called automatic stop that automatically stops the engine when a predetermined condition is satisfied, but includes so-called forced stop that forcibly stops the engine according to the driver's intention.

The engine is a four-cycle engine having three or more cylinders, and the variable valve mechanism is configured to open the intake valve so that the lift amount of the intake valve is greater than or equal to a predetermined value during the stop control of the engine. the you short.

  As described above, in a four-cycle engine having three or more cylinders, in a normal operation state, a part of the valve opening periods of the intake valves overlap each other, but by shortening the valve opening period of each intake valve, It is possible to set a full intake valve closing period in which all intake valves are closed.

  Moreover, when the lift amount of the intake valve is set to a predetermined value or more, the next time the engine is started, it can be started smoothly.

  The intake valve is configured to be lifted by a camshaft driven by the crankshaft, and the variable valve mechanism is configured such that a part of the valve opening periods of the intake valve overlap when the engine operates at a high load. Alternatively, a valve opening period of the intake valve may be set.

  By doing so, when the engine performs a high load operation, the valve opening period of the intake valve becomes longer, and it is possible to ensure a sufficient filling amount corresponding to the high load operation.

The multi-cylinder direct injection engine stop control device disclosed herein also includes an engine having a plurality of cylinders, a fuel injection valve configured to inject fuel directly into each cylinder, and rotation of the crankshaft of the engine. By an intake valve configured to open and close an intake port connected to each cylinder by lifting in synchronization, a variable valve mechanism configured to change a valve opening period of the intake valve, and the fuel injection valve A stop control unit configured to perform engine stop control in a period from the start of fuel cut to stop the fuel supply to the engine until the engine stops, the stop control unit, The variable valve mechanism shortens the intake valve opening period of each cylinder so that the entire intake valve closing period in which all the intake valves are closed is set. The engine is in the full intake valve closing period of the crank angle position at the time of halting, the variable valve mechanism such that said valve closing timing of the intake valve later than the intake bottom dead center, the opening of the intake valve set the valve period, the variable valve mechanism, when the stop control of the engine by retarding the opening timing of the intake valve, you shorten the opening period of the intake valve.

  By doing so, if the valve opening period of the intake valve is shortened during engine stop control, the valve closing timing is set after the intake bottom dead center. Here, for example, when the engine is automatically started after the engine is automatically stopped, the engine is in a warm state, so that a warm lock (that is, that the cylinder is at a high temperature and a high pressure and self-ignition occurs in the compression stroke) As a result, reverse torque is generated and engine startability deteriorates). On the other hand, when the engine is started, if the valve opening period of the intake valve is short and the valve closing timing is set after the intake bottom dead center, compression in the cylinder is substantially suppressed. It is possible to effectively avoid the occurrence of warm lock.

The multi-cylinder direct injection engine stop control device disclosed herein also includes an engine having a plurality of cylinders, a fuel injection valve configured to inject fuel directly into each cylinder, and rotation of the crankshaft of the engine. By an intake valve configured to open and close an intake port connected to each cylinder by lifting in synchronization, a variable valve mechanism configured to change a valve opening period of the intake valve, and the fuel injection valve A stop control unit configured to perform engine stop control in a period from the start of fuel cut to stop the fuel supply to the engine until the engine stops, the stop control unit, The variable valve mechanism shortens the intake valve opening period of each cylinder so that the entire intake valve closing period in which all the intake valves are closed is set. The crank angle position when the engine is completely stopped is set within the all intake valve closing period, and the stop control unit is configured to drive the spark plug in the cylinder that has reached the compression stroke after starting the fuel cut. Has been.

By doing so, it is possible to burn the unburned fuel remaining in the cylinder after the fuel cut is started and until the engine is stopped. As a result, the amount of unburned fuel remaining in the cylinder after the engine is completely stopped is reduced as much as possible to suppress the generation of evaporative gas.

The stop control unit may drive the spark plug in a plurality of the cylinders.

By doing so, unburned fuel can be burned in each of the plurality of cylinders to which the fuel injection valves are individually attached, and the generation of evaporative gas is suppressed.

The variable valve mechanism may shorten the valve opening period of the intake valve during a period from the start of the fuel cut to the stop of the engine.

By so doing, engine stop control is appropriately performed, and when the engine is completely stopped, all intake ports can be closed.

  As described above, according to the stop control device for a multi-cylinder direct injection engine, when the engine is completely stopped, the intake ports of all the cylinders are closed, so that they adhere to the wall surface in the cylinder. Even if the fuel or the fuel coming out of the fuel injection valve due to oil-tight leakage evaporates while the engine is stopped, it can be prevented from being released into the atmosphere through the intake passage.

It is a conceptual diagram which shows the structure of a multicylinder engine. It is a block diagram which shows the structure which concerns on control of a multicylinder engine. It is a figure explaining the crank angle position at the time of a complete stop of a multi-cylinder engine.

  The multi-cylinder direct injection engine stop control device disclosed herein will be described below with reference to the drawings. The following description is an example. FIG. 1 is a diagram showing a configuration of a multi-cylinder direct injection engine (hereinafter simply referred to as an engine) that is mounted on a vehicle and generates a driving force for traveling.

  The engine 1 is a four-cycle four-cylinder reciprocating engine having a first cylinder 11, a second cylinder 12, a third cylinder 13, and a fourth cylinder 14, and four first to fourth cylinders 11 to 14 are illustrated. They are arranged in series along an omitted crankshaft (ie, output shaft). Two intake ports 201, 201 are connected to each cylinder 11-14. The two intake ports 201 and 201 are connected to an intake passage (not shown).

  Each intake port 201 is opened and closed by the intake valve 21. The intake valve 21 is connected to the crankshaft and opened and closed by a camshaft 22 that rotates in synchronization with the crankshaft. Accordingly, the intake port 201 opens and closes in synchronization with the rotation of the crankshaft.

  The intake valve driving device includes a variable valve mechanism configured to be able to change a valve opening period of the intake valve. Specifically, the variable valve mechanism is a CVVL (Continuously Variable Valve Lift) 28 configured to change the valve opening period as the lift amount of the intake valve is continuously changed. The variable valve mechanism is not limited to CVVL, and various mechanisms can be adopted as long as the valve opening period can be changed.

  Two exhaust ports 203, 203 are connected to each cylinder 11-14. The two exhaust ports 203 and 203 are connected to an exhaust passage (not shown). Each exhaust port 203 is opened and closed by an exhaust valve 23. The exhaust valve 23 is connected to the crankshaft and is opened and closed by a camshaft 24 that rotates in synchronization with the crankshaft. Accordingly, the exhaust port 203 also opens and closes in synchronization with the rotation of the crankshaft.

  A spark plug 25 for igniting the air-fuel mixture in the combustion chamber is attached to each cylinder 11-14. Although not shown in FIG. 1, each cylinder 11-14 is provided with a fuel injection valve 26 (see FIG. 2) for directly injecting fuel into the cylinder.

  FIG. 2 shows a configuration related to the control of the engine 1. The multi-cylinder engine stop control device includes a PCU (Powertrain Control Unit) 81 as a control unit. The PCU 81 includes an accelerator opening sensor 82 that detects the accelerator opening, a vehicle speed sensor 83 that detects the vehicle speed, and a crank angle sensor that predicts and / or detects the stop position of the engine 1. A position sensor 84 is connected. Each of the sensors 82 to 84 outputs a detection signal to the PCU 81.

  As control of the engine 1, the PCU 81 is a fuel injection valve 26 configured to inject fuel supplied into the cylinders 11 to 14, and an ignition plug 25 configured to ignite an air-fuel mixture in the cylinders 11 to 14. Then, a control signal is output to the throttle valve 27 configured to adjust the amount of air taken in by the engine 1. The PCU 81 also changes the valve opening period of the intake valve 21 by outputting a control signal to the CVVL 28. The PCU 81 further outputs a signal to the auxiliary machine 29 driven by the engine 1. Here, the auxiliary machine 29 is driven by the engine 1 and simultaneously imparts rotational resistance to the engine 1. Specifically, the auxiliary machine 29 is a generator (alternator) or a compressor of an air conditioner.

  Next, stop control of the multi-cylinder direct injection engine will be described with reference to FIG. First, the upper diagram of FIG. 3 exemplifies the valve lift of the intake valve 21 and the valve lift of the exhaust valve 23 of each cylinder 11 to 14 at the time of high load operation in the four-cycle four-cylinder reciprocating engine 1 ( (See the solid line in the figure). The horizontal axis is the crank angle. At least during high load operation, the lift amount of the intake valve 21 is set large and the valve opening period is set long by the CVVL 28. Thereby, the filling amount commensurate with the high load operation is ensured. During normal operation of the engine 1, part of the valve opening periods of the intake valves 21 overlap each other. As a result, one of the intake valves 21 is open with respect to the crank angle position. In other words, there is substantially no state where all the intake valves 21 are closed.

  The stop control device evaporates fuel adhering to the wall surfaces in the cylinders 11 to 14 or fuel exiting from the fuel injection valve 26 due to oil-tight leakage or the like while the engine 1 is stopped. It is configured to prevent it from being released into the atmosphere. Specifically, the PCU 81 causes the intake valves 21 to close the intake ports of all the cylinders 11 to 14 when the engine 1 is stopped by automatic stop or forced stop. As described above, during normal operation of the engine 1, there is substantially no state where all the intake valves 21 are closed. Therefore, when stopping the engine 1, the PCU 81 shortens the valve opening period of each intake valve 21 by the CVVL 28 (see the white arrow), as shown in the lower diagram of FIG. A full intake valve closing period in which the intake valves 21 are closed is set (see the hatched period in the figure).

  Here, when shortening the valve opening period of each intake valve 21, the valve opening period is shortened by retarding the valve opening timing of the intake valve 21, or the valve closing timing of the intake valve 21 is advanced. It is conceivable to shorten the valve opening period. In either case, the valve opening period of each intake valve 21 is shortened. In this example, the PCU 81 shortens the valve opening period by retarding the valve opening timing of the intake valve 21. By doing so, the closing timing of the intake valve 21 is made after the intake bottom dead center.

  The PCU 81 also controls the stop position of the engine 1 (that is, the crank angle position) within the full intake valve closing period through the control of the auxiliary machine 29.

  Specifically, the PCU 81 stops the fuel injection by the fuel injection valve 26 in order to stop the engine 1 (that is, a period in which the rotational speed of the engine 1 gradually decreases by starting the fuel cut). Based on the signal from the engine stop position sensor 84, a load is appropriately applied to the engine 1 by the auxiliary machine 29 so that the stop position of the engine 1 is within the entire intake valve closing period. Control for applying a load to the engine 1 by the auxiliary machine 29 when the engine 1 is stopped is known, and various controls can be appropriately employed. Therefore, detailed description is omitted here.

  The PCU 81 also drives the spark plug 25 at a predetermined timing in the cylinders 11 to 14 that have reached the compression stroke during a period from when the fuel cut of the engine 1 is started to when the engine 1 is stopped. The spark plug 25 is driven for the plurality of cylinders 11 to 14. As a result, unburned fuel remaining in the cylinders 11 to 14 is burned.

  Thus, by the control when the engine 1 is stopped, the stop position when the engine 1 is completely stopped can be set within the all intake valve closing period. The intake ports 201 of all the cylinders 11 to 14 are closed by the intake valve 21. Thereby, even if unburned fuel evaporates in each cylinder 11-14, the evaporated gas is prevented from being discharged into the atmosphere from the intake port 201 through the intake passage.

  In addition, while the engine 1 is about to stop, driving the spark plug 25 causes the unburned fuel remaining in the cylinders 11 to 14 to burn as much as possible, so the unburned fuel evaporates in the cylinders 11 to 14. That itself is prevented.

(Summary)
As described above, the multi-cylinder direct injection engine stop control device disclosed herein is an engine 1 having a plurality of cylinders 11 to 14 and a fuel configured to directly inject fuel into each cylinder 11 to 14. The intake valve 21 configured to open and close the intake port 201 connected to each of the cylinders 11 to 14 by lifting in synchronism with the rotation of the injection valve 26, the crankshaft of the engine 1, and the intake valve 21 The variable valve mechanism (CVVL 28) configured to change the valve opening period and the time from the start of the fuel cut to stop the fuel supply to the engine 1 by the fuel injection valve 26 until the engine 1 stops A stop control unit (PCU 81) configured to perform stop control of the engine 1 during the period.

  The PCU 81 shortens the valve opening period of the intake valves 21 of the cylinders 11 to 14 by the CVVL 28 so that the all intake valve closing period in which all the intake valves 21 are closed is set. At the same time, the crank angle position when the engine 1 is completely stopped is set within the all intake valve closing period.

  As a result, when the engine 1 is completely stopped, the intake ports 201 of all the cylinders 11 to 14 are in a closed state, so that fuel that has adhered to the wall surfaces in the cylinders 11 to 14 or fuel injection due to oil tight leakage Even if the fuel or the like coming out of the valve 26 evaporates while the engine 1 is stopped, the evaporated gas is prevented from being released into the atmosphere through the intake passage.

  The engine 1 is a four-cycle engine having three or more cylinders. The CVVL 28 controls the intake valve 21 so that the lift amount of the intake valve 21 is equal to or greater than a predetermined value when the engine 1 is stopped. Shorten the valve opening period.

  When stopping the engine 1, the lift amount of the intake valve 21 is set to a predetermined value or more, so that when the stopped engine 1 is to be started, it can be started smoothly.

  The intake valve 21 is configured to be lifted by a camshaft 22 driven by the crankshaft. When the engine 1 is operated at a high load, the CVVL 28 has a part of the valve opening period of the intake valve 21. The valve opening period of the intake valve 21 is set so as to overlap.

  By doing so, when the engine 1 performs a high load operation, the valve opening period of the intake valve 21 is lengthened, and it is possible to sufficiently secure a filling amount commensurate with the high load operation.

  The CVVL 28 sets a valve opening period of the intake valve 21 so that the closing timing of the intake valve 21 is after intake bottom dead center, and the CVVL 28 controls the engine 1 during the stop control of the engine 1. By delaying the opening timing of the intake valve 21, the valve opening period of the intake valve 21 is shortened.

  By doing so, the closing timing of the intake valve 21 is set after the intake bottom dead center during the stop control of the engine 1. Here, for example, when the engine 1 is automatically started after the engine 1 is automatically stopped, the engine 1 is in a warm state. Therefore, there is a possibility that a warm lock may occur. On the other hand, when the engine 1 is started, the intake valve Since the compression stroke period is substantially shortened and the compression of the gas in the cylinders 11 to 14 is suppressed, the warm lock is generated. It can be effectively avoided.

  The CVVL 28 shortens the valve opening period of the intake valve 21 during the period from the start of the fuel cut until the engine 1 stops.

  By so doing, the stop control of the engine 1 is appropriately performed, and when the engine 1 is completely stopped, all the intake ports 201 can be closed.

  The PCU 81 is configured to drive the spark plug 25 in the cylinders 11 to 14 that have reached the compression stroke after starting the fuel cut.

  By doing so, it is possible to burn the unburned fuel remaining in the cylinders 11 to 14 until the engine 1 is stopped after the fuel cut is started. As a result, the amount of unburned fuel remaining in the cylinders 11 to 14 after the engine 1 is completely stopped is reduced as much as possible to suppress the generation of evaporative gas.

  The PCU 81 drives the spark plug 25 in the plurality of cylinders 11 to 14.

  By doing so, unburned fuel can be burned in each of the plurality of cylinders 11 to 14 to which the fuel injection valves 26 are individually attached, and the generation of evaporative gas is suppressed.

  In the above description, the technique disclosed herein has been described by taking a four-cylinder reciprocating engine as an example, but the present invention is not limited to a four-cylinder reciprocating engine, and can be widely applied to engines having three or more cylinders. Further, in the 4-cycle 2-cylinder reciprocating engine, a period for closing all the intake valves is set without shortening the intake valve opening period. The disclosed technology may be applied.

  Further, the target engine is not limited to an engine that generates driving force for traveling, and can be applied to, for example, an engine mounted on a hybrid vehicle or a plug-in hybrid vehicle. The engine mounted on the hybrid vehicle or the plug-in hybrid vehicle may be an engine for driving the generator, or an engine for driving and driving the generator. Furthermore, the technology disclosed herein may be applied to an engine of a range extender device that is mounted on an electric vehicle and extends a cruising range.

1 Multi-cylinder direct injection engine 11-14 Cylinder 21 Intake valve 201 Intake port 25 Spark plug 26 Fuel injection valve 28 CVVL (variable valve mechanism)
29 Auxiliary machine 81 PCU (stop control unit)

Claims (6)

An engine having a plurality of cylinders;
A fuel injection valve configured to inject fuel directly into each cylinder;
An intake valve configured to open and close intake ports connected to each cylinder by lifting in synchronization with rotation of the crankshaft of the engine;
A variable valve mechanism configured to change a valve opening period of the intake valve;
A stop control unit configured to perform engine stop control in a period from the start of fuel cut to stop fuel supply to the engine by the fuel injection valve until the engine stops; and
The stop control unit shortens the opening period of the intake valve of each cylinder by the variable valve mechanism so that the entire intake valve closing period in which all the intake valves are closed is set, The crank angle position when the engine is completely stopped is within the all intake valve closing period ,
The engine is a four-cycle engine having three or more cylinders,
The variable valve mechanism is a stop control device for a multi-cylinder direct injection engine that shortens the valve opening period of the intake valve so that the lift amount of the intake valve becomes equal to or greater than a predetermined amount during the stop control of the engine. The stop control device for a multi-cylinder direct injection engine according to claim 1 ,
The intake valve is configured to lift by a camshaft driven by the crankshaft;
The variable valve mechanism is a stop control device for a multi-cylinder direct injection engine that sets a valve opening period of the intake valve so that parts of the valve opening periods of the intake valve overlap each other when the engine operates at a high load. . An engine having a plurality of cylinders;
A fuel injection valve configured to inject fuel directly into each cylinder;
An intake valve configured to open and close intake ports connected to each cylinder by lifting in synchronization with rotation of the crankshaft of the engine;
A variable valve mechanism configured to change a valve opening period of the intake valve;
A stop control unit configured to perform engine stop control in a period from the start of fuel cut to stop fuel supply to the engine by the fuel injection valve until the engine stops; and
The stop control unit shortens the opening period of the intake valve of each cylinder by the variable valve mechanism so that the entire intake valve closing period in which all the intake valves are closed is set, The crank angle position when the engine is completely stopped is within the all intake valve closing period,
The variable valve mechanism sets a valve opening period of the intake valve so that the closing timing of the intake valve is after intake bottom dead center,
The variable valve mechanism is a stop control device for a multi-cylinder direct injection engine that shortens the valve opening period of the intake valve by retarding the valve opening timing of the intake valve during stop control of the engine. An engine having a plurality of cylinders;
A fuel injection valve configured to inject fuel directly into each cylinder;
An intake valve configured to open and close intake ports connected to each cylinder by lifting in synchronization with rotation of the crankshaft of the engine;
A variable valve mechanism configured to change a valve opening period of the intake valve;
A stop control unit configured to perform engine stop control in a period from the start of fuel cut to stop fuel supply to the engine by the fuel injection valve until the engine stops; and
The stop control unit shortens the opening period of the intake valve of each cylinder by the variable valve mechanism so that the entire intake valve closing period in which all the intake valves are closed is set, The crank angle position when the engine is completely stopped is within the all intake valve closing period,
The stop control unit is a stop control device for a multi-cylinder direct injection engine configured to drive a spark plug in the cylinder that has undergone a compression stroke after starting the fuel cut. The stop control device for a multi-cylinder direct injection engine according to claim 4 ,
The stop control unit is a stop control device for a multi-cylinder direct injection engine that drives the spark plug in a plurality of the cylinders. In the stop control device for a multi-cylinder direct injection engine according to any one of claims 1 to 5 ,
The variable valve mechanism is a stop control device for a multi-cylinder direct injection engine that shortens the valve opening period of the intake valve during a period from the start of the fuel cut until the engine stops.

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