JP2011085052A - Controller for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller 2 for an internal combustion engine 1 capable of reducing unburned components included in emission at starting. <P>SOLUTION: In the controller 2 for the internal combustion engine 1 including a fuel injection valve 5 included per each cylinder of the internal combustion engine 1, a fuel supply means 4 for supplying fuel in a fuel tank to the fuel injection valve 5, and a scavenging means 3 for scavenging the inside of a combustion chamber 13, a fuel pressure acquiring means 2a is provided for acquiring fuel pressure acting on the fuel injection valve 5, and when it is determined that the fuel pressure has been lowered, and it reaches a predetermined threshold or lower during the stop of the supply of fuel by the fuel injection valve 5, scavenging is carried out by the scavenging means 3. An active state determining means 2b is provided for determining whether or not a purifier 6 purifying exhaust from the combustion chamber 13 is in an active state, and if it is determined that the purifier 6 is not in the active state, scavenging by the scavenging means 3 is prohibited. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine including scavenging means for scavenging residual fuel.

  Immediately after the internal combustion engine is stopped due to the engine stop condition being established, the motoring of the internal combustion engine is executed by the motor, and the air flow generated in the intake passage is used to forcibly scavenge the fuel adhering to the intake passage. It has been proposed (see, for example, Patent Document 1). In this proposal, a motor for motoring the internal combustion engine is the scavenging means.

JP 2004-144030 A

  If the fuel remaining in the intake passage is scavenged immediately after the internal combustion engine is stopped, the intake passage becomes negative pressure without the fuel pressure applied to the injector being sufficiently reduced, so that fuel leaks from the injector and the scavenging effect is reduced. In some cases, it was not possible to get enough.

  Therefore, an object of the present invention is to provide a control device for an internal combustion engine that can reduce unburned components contained in emissions at the time of starting.

The present invention controls an internal combustion engine comprising a fuel injection valve provided for each cylinder of the internal combustion engine, fuel supply means for supplying fuel in the fuel tank to the fuel injection valve, and scavenging means for scavenging the combustion chamber. In the device
A fuel pressure grasping means for grasping a fuel pressure applied to the fuel injection valve;
The scavenging means is made to perform scavenging when it is determined that the fuel pressure decreases and is not more than a predetermined threshold while the fuel supply by the fuel injection valve is stopped.

  According to this, since the scavenging is performed after the fuel pressure becomes equal to or lower than the predetermined threshold and the fuel does not leak from the fuel injection valve, the fuel does not leak after scavenging. Unburned components contained in the emission of time can be reduced.

Further, in the present invention, there is an active state determination unit that determines whether or not the purification device that purifies the exhaust gas from the combustion chamber is in an active state,
When it is determined that the purifying device is not in an active state, it is preferable to prohibit the scavenging means from performing scavenging.

  According to this, since scavenging is performed when the purifying device is in an active state, the exhaust gas containing the scavenged fuel can be purified by the purifying device.

  ADVANTAGE OF THE INVENTION According to this invention, the control apparatus of the internal combustion engine which can reduce the unburned component contained in the emission at the time of starting can be provided.

It is a block diagram of the internal combustion engine provided with the control apparatus which concerns on embodiment of this invention. It is a flowchart of the engine stop method and the scavenging method which the control apparatus which concerns on embodiment of this invention implements. It is a timing chart of (a) fuel injection permission flag, (b) CAT temperature, (c) NE, (d) fuel pressure, and (e) remaining HC. It is a block diagram of an internal combustion engine, (a) shows a state where fuel is leaking, (b) shows a state where fuel is stagnating, and (c) shows a state where scavenging is performed. . It is a CAT temperature map with respect to a NE-PB plane (matrix).

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.

  In FIG. 1, the block diagram of the internal combustion engine 1 provided with the control apparatus 2 which concerns on embodiment of this invention is shown. The internal combustion engine 1 includes a cylinder 11, a piston 12, a connecting rod 14, a crankshaft 15, a flywheel 16, and an NE sensor 18. A space surrounded by the cylinder 11 and the piston 12 becomes a combustion chamber 13, and fuel continuously explodes in the combustion chamber 13. Due to this explosion, the piston 12 reciprocates in the cylinder 11, and this reciprocating motion is transmitted to the crankshaft 15 via the connecting rod 14, and the crankshaft 15 and the flywheel 16 rotate. An NE sensor 18 is provided in the vicinity of the flywheel 16. Since the flywheel 16 rotates integrally with the crankshaft 15, the rotational speed NE of the flywheel 16 can be detected by the NE sensor 18. Then, the control device 2 can acquire the rotational speed NE of the crankshaft 15 from the NE sensor 18.

  Further, the internal combustion engine 1 includes an intake port 7 communicating with the combustion chamber 13, an intake valve 9 that opens and closes the intake port 7, a fuel injection valve 5 that injects fuel into the intake port 7, and a fuel that applies fuel pressure. Fuel supply means 4 for supplying the fuel to the fuel injection valve 5. The fuel supply means 4 is supplied to the fuel injection valve 5 so as not to cause a temporal pressure fluctuation such as pulsation, a fuel tank that stores fuel, a fuel pump that pumps the fuel by applying a high fuel pressure. And a pressure regulator that keeps the fuel pressure of the fuel on the side of the fuel tank high and constant. The fuel whose fuel pressure has been increased is injected from the fuel injection valve 5 into the intake port 7. The fuel injected into the intake port 7 is introduced into the combustion chamber 13 together with the air guided to the intake port 7 during the intake stroke when the intake valve 9 is open, and explodes in the combustion chamber 13. Become. The fuel pump may be operated by rotation of a cam attached to the end of the camshaft for the intake / exhaust valves 9 and 10, or an electric fuel pump may be used.

  Further, the internal combustion engine 1 includes an exhaust port 8 communicating with the combustion chamber 13, an exhaust valve 10 for opening and closing the exhaust port 8, an exhaust pipe 17 connected to the exhaust port 8 is connected to an exhaust pipe 17 A purifier (CAT) 6, a PB sensor 19 provided in the vicinity of the intake pipe 23 for measuring the pressure (PB) in the intake pipe 23, and a temperature sensor 20 provided in the vicinity of the CAT 6 for measuring the temperature of the CAT 6 are provided. is doing. The fuel and air introduced into the combustion chamber 13 are ignited and explode / combust in the combustion chamber 13. The exhaust gas after combustion enters the exhaust port 8 during the exhaust stroke in which the exhaust valve 10 is open, is purified by the CAT 6 through the exhaust pipe 17, and is exhausted to the outside.

  In addition, as shown in FIG. 1, the internal combustion engine 1 includes scavenging means 3 and a belt 21 that transmits the rotational motion of the scavenging means 3 to the crankshaft 15. In Figure 1, ACG for converting power to transmit the power through the crank shaft 15 belt 21 (auxiliary alternator) and used as a motor serving as a power source, an example is made to function as scavenging means 3 Show. As the scavenging means 3 is not limited thereto, may be used starter motor for rotating the flywheel 16 directly, in the hybrid vehicle may be used hybrid motor. That is, as the scavenging means 3, a motor such as an ACG, a starter motor, or a hybrid motor can be used. First, when the internal combustion engine 1 is started, the control device 2 controls and rotates the scavenging means (motor, starter (motor)) 3 to perform so-called motoring. By this motoring, the crankshaft 15 and the flywheel 16 rotate, and the piston 12 reciprocates. Since the intake valve 9 is open in the cylinder that is in the intake stroke at the time of starting, when fuel is injected from the fuel injection valve 5, the fuel is introduced into the combustion chamber 13. The motoring ignites the fuel through the intake stroke and the compression stroke, and the fuel explodes (initial explosion and expansion stroke). By this initial explosion, the crankshaft 15 and the flywheel 16 can maintain the rotation without depending on the rotation of the scavenging means (motor, starter) 3, and the control device 2 can control the internal combustion engine 1 from the control at the initial operation. Go to normal operation control.

  On the other hand, when the internal combustion engine 1 is stopped, the scavenging means (motor, starter) 3 scavenges the intake passage, that is, the intake port 7 and the combustion chamber 13. When the internal combustion engine 1 is stopped, the fuel injection by the fuel injection valve 5 stops and the fuel does not explode in the combustion chamber 13. Therefore, the reciprocating motion of the piston 12 is not performed by the scavenging means (motor, starter) 3. I can't let you. Specifically, when the internal combustion engine 1 is stopped, the control device 2 controls and rotates the scavenging means (motor, starter) 3 to perform so-called motoring. By rotating the crankshaft 15 and the flywheel 16 by this motoring, the piston 12 reciprocates and the volume of the combustion chamber 13 fluctuates. At the same time, the intake valve 9 and the exhaust valve 10 are opened and closed, and air pumping is performed. Done, an air flow occurs. The air flows through the intake port 7, the combustion chamber 13, the exhaust port 8, the exhaust pipe 17, and the CAT 6 in this order. When the air flows through the intake port 7 and the combustion chamber 13, the air advances while vaporizing the fuel adhering to the wall surface. Thus, so-called scavenging can be performed to remove the fuel remaining in the intake port 7 and the combustion chamber 13. Then, the air flows to the CAT 6 while containing the fuel, and the fuel contained in the air is removed by the CAT 6. In FIG. 1, one cylinder is shown, and the other cylinders are omitted. That is, the internal combustion engine 1 has a plurality of cylinders, and each cylinder has the same structure except that the combustion cycle is shifted. For example, a fuel injection valve 5 is provided for each cylinder.

  The internal combustion engine 1 has a control device 2. The control device 2 performs control at the time of starting the internal combustion engine 1, control including scavenging at the time of stop, and control of normal operation from after start to before stop. The control device 2 includes a fuel pressure grasping means 2a, an active state determining means 2b, and a timer 2c.

  The fuel pressure grasping means 2a grasps the current fuel pressure applied to the fuel injection valve 5, and in particular can determine whether or not the fuel pressure is equal to or less than a predetermined (pressure) threshold at which leakage does not occur. To the extent, grasp the magnitude of the fuel pressure. Therefore, as a grasp of the fuel pressure, a fuel pressure sensor may be mounted in the vicinity of the fuel injection valve 5 to detect the fuel pressure, and this fuel pressure may be grasped directly. Further, when the internal combustion engine 1 is stopped, the fuel supply means 4, particularly the operation of the fuel pump, is also stopped as the fuel injection by the fuel injection valve 5 stops. For this reason, the fuel pressure applied to the fuel injection valve 5 gradually decreases immediately after the internal combustion engine 1 is stopped. When the fuel pressure is reduced to the predetermined (pressure) threshold, no leakage occurs. Here, it considered the situation to decrease the fuel pressure is substantially the same for each of the stopping internal combustion engine 1, the time from the stop the internal combustion engine 1 until the fuel pressure is lowered to the predetermined (pressure) threshold, the internal combustion engine 1 It becomes substantially constant at every stop. Therefore, a certain time from when the internal combustion engine 1 is stopped until the fuel pressure falls below the predetermined (pressure) threshold can be set as the predetermined time threshold. Then, as the grasping of the fuel pressure, the time (time) from the stop the internal combustion engine 1 measured by the timer 2c, the measurement time, by determining whether a predetermined time threshold or causing no leakage, indirect Therefore, grasp the current level of fuel pressure. Control device 2, the fuel pressure is below the predetermined threshold value, the measurement time from the stop the internal combustion engine 1 becomes equal to or larger than the prescribed time threshold, since the fuel is no longer Mora from the fuel injection valve 5, thereby carrying out the scavenging. Since fuel does not leak after scavenging, it is possible to reduce unburned components (fuel) contained in the emissions at the time of starting the internal combustion engine 1 performed after scavenging.

  The active state determination means 2b determines whether or not the CAT 6 that purifies the exhaust gas from the combustion chamber 13 is in an active state. The CAT 6 is in an active state in which exhaust gas can be purified at a predetermined temperature threshold value or more. Therefore, in determining whether the CAT 6 is in an active state, specifically, it is determined whether the temperature of the CAT 6 is equal to or higher than the predetermined temperature threshold. For this reason, it is necessary to grasp the temperature of CAT6. In order to grasp the temperature of the CAT 6, the temperature sensor 20 may be mounted in the vicinity of the CAT 6 and the temperature of the CAT 6 may be directly grasped. Further, the temperature of the CAT 6 is raised to the predetermined temperature threshold or more due to heat generated by the explosion of the fuel in the combustion chamber 13. Accordingly, the temperature of the heated CAT 6 depends on the state of fuel explosion in the combustion chamber 13. Specifically, the higher the frequency of explosions, the higher the temperature of CAT6. Since the frequency of explosions is proportional to the rotational speed NE of the crankshaft 15, the higher the rotational speed NE, the higher the temperature of the CAT6. Further, the temperature of the CAT 6 is grasped based on the pressure (PB) in the intake pipe 23. By knowing the amount of air required for the explosion of the internal combustion engine 1, the temperature of the CAT 6 can be estimated. However, since the amount of air required for the explosion of the internal combustion engine 1 can be estimated from the pressure (PB) in the intake pipe 23, the intake pipe Therefore, the temperature of CAT 6 can be estimated from the pressure (PB) in the cylinder 23. As the pressure (PB) in the intake pipe 23 increases, the amount of air required for the explosion of the internal combustion engine 1 can be increased, and the temperature of the CAT 6 can be increased. From these, it is possible to indirectly grasp the current temperature of the CAT 6 based on the current rotational speed NE and the pressure (PB) in the intake pipe 23. That is, when the internal combustion engine 1 is stopped, the temperature of the CAT 6 at the time of stop can be indirectly grasped based on the rotational speed NE immediately before the stop and the pressure (PB) in the intake pipe 23. When the internal combustion engine 1 stops, the heat source is lost, and the temperature of the CAT 6 gradually decreases from the temperature immediately before the internal combustion engine 1 stops due to heat dissipation. The degree of the decrease is determined by the heat dissipation path, and the heat dissipation path and the temperature decrease are considered to be substantially the same every time the internal combustion engine 1 is stopped. Temperature CAT6 when stopping (Further, the rotational speed NE and the pressure in the intake pipe 23 (PB)) based on the elapsed time from the stop to the current (measurement time), the temperature of CAT6 the current indirectly I can grasp it. It is determined whether or not the detected temperature of the CAT 6 is equal to or higher than the predetermined temperature threshold value. And the control apparatus 2 can determine whether CAT6 is an active state. When it is determined that the CAT 6 is not in the active state, the control device 2 can prohibit the scavenging means 3 from performing the scavenging. Since scavenging is performed when the CAT 6 is in an active state, the exhaust (air) containing the scavenged fuel can be purified by the CAT 6.

  FIG. 2 shows a flowchart of an engine stop method and a scavenging method performed by the control device 2 according to the embodiment of the present invention. The engine stop method starts when the internal combustion engine 1 is in operation. First, the engine stop method will be described, and then the scavenging method will be described.

  First, in step S10 of the engine stop method, the control device 2 determines whether or not an engine stop condition is satisfied. As the engine stop condition, in manual stop, for example, the ignition switch (IG) is turned off. Also, the conditions for establishing an idle stop are engine stop conditions. As the conditions for establishing the idle stop, for example, a condition that the brake pedal is kept depressed even when the vehicle stops, a condition that the electric power consumed by an electric device such as an air conditioner is a predetermined value or less, and the like are set. ing. When the engine stop condition is satisfied (step S10, Yes), the process proceeds to step S11 and the scavenging method is started. If the engine stop condition is not satisfied (step S10, No), the process returns to step S10, and step S10 is repeated until the engine stop condition is satisfied.

  Next, in step S11, as shown in FIG. 3A, the control device 2 receives the establishment of the engine stop condition in step S10, and sets the fuel injection permission flag to “1” in the state where the flag is set. It is set to “0” in the state of being defeated. By setting the fuel injection permission flag (fuel injection permission flag = 1), the control device 2 stops the fuel injection valve 5 from injecting fuel. As a result, the explosion of the fuel in the combustion chamber 13 does not occur, the rotational speed NE of the crankshaft 15 and the flywheel 16 decreases as shown in FIG. 3C, the rotation stops, and the internal combustion engine 1 Stops. Further, as shown in FIG. 3B, the temperature of the CAT 6 also starts to decrease.

  In step S <b> 12, the control device 2 stops the supply of fuel to the fuel injection valve 5 by the fuel supply unit 4. Specifically, the operation of the fuel pump in the fuel supply means 4 is stopped, or the fuel pressure control of the pressure regulator is turned off and the valve is opened. As a result, as shown in FIG. 3D, the fuel pressure applied to the fuel injection valve 5 starts to decrease. This completes the engine stop method.

  Next, the scavenging method will be described. First, in step S1 of the scavenging method, the control device 2 determines whether or not the fuel injection by the fuel injection valve 5 is stopped. Specifically, it is determined whether or not the fuel injection permission flag is “0” in a collapsed state. Then, in conjunction with step S11 of the engine stop method, when the fuel injection permission flag becomes “0” and the fuel injection is stopped (step S1, Yes), the process proceeds to step S2. While the fuel injection permission flag is "1", if the fuel injection is not stopped (Step S1, No), the process returns to step S1, the fuel injection permission flag is "0", fuel injection is stopped Step S1 is repeated until.

  Next, in step S2, the control device 2 starts time measurement by the timer 2c. As shown in FIG. 3A, the timer 2c can acquire the elapsed time from immediately after the stop of the fuel injection by measuring the time immediately after the stop of the fuel injection. On the other hand, as shown in FIG. 4 (a), the fuel 22 is leaked from the fuel injection valve 5 into the intake port 7, as shown in FIG. 4 (b), the fuel 22 is accumulated in the intake port 7. Then, as shown in FIG. 3E, the hydrocarbon (HC) remaining in the internal combustion engine 1 rises by the amount of the leaked fuel 22 minutes.

  In step S <b> 3, the fuel pressure grasping means 2 a of the control device 2 grasps the fuel pressure applied to the fuel injection valve 5. As shown in FIG. 4 (a), the port injection type of control device 2 in which the fuel 22 is injected into the intake port 7 by obtaining the elapsed time by the timer 2c (measurement time), indirectly fuel pressure To grasp. Although not shown, in the direct injection type control device 2 in which the fuel 22 is injected into the combustion chamber 13, a fuel pressure sensor (not shown) attached in the vicinity of the fuel injection valve 5 is applied to the fuel injection valve 5. The fuel pressure is directly grasped (acquired) by detecting the fuel pressure.

  In step S <b> 4, the control device 2 determines whether or not the fuel 22 leaks into the intake port 7 or into the combustion chamber 13. Specifically, as shown in FIG. 3D, it is determined whether or not the elapsed time (measurement time) by the timer 2c is equal to or greater than a predetermined time threshold that is a time when leakage stops. Alternatively, it is determined whether or not the fuel pressure by the fuel pressure sensor has become equal to or less than a predetermined pressure threshold that is a fuel pressure at which leakage stops. Then, the time elapsed by the timer 2c becomes greater than a predetermined time threshold, or determines that the fuel pressure by the fuel pressure sensor is below a predetermined pressure threshold, leakage into the intake port 7 or the combustion chamber 13 of the fuel 22 does not occur If yes (step S4, Yes), the process proceeds to step S5. The elapsed time by the timer 2c does not become more than a predetermined time threshold, or not the fuel pressure by the fuel pressure sensor is below a predetermined pressure threshold, leakage into the intake port 7 or the combustion chamber 13 of the fuel 22 does not occur If it is not determined (step S4, No), the process returns to step S3, and steps S3 and S4 are repeated until it is determined in step S4 that no leakage of the fuel 22 has occurred.

  In step S <b> 5, the active state determination unit 2 b of the control device 2 grasps the temperature of the CAT 6. The temperature of the CAT 6 may be directly grasped (acquired) by the temperature sensor 20 mounted in the vicinity of the CAT 6. The temperature of CAT6 before engine stop, as shown in FIG. 5, the higher the higher the rotational speed NE of the crankshaft 15 becomes higher the higher the pressure in the intake pipe 23 (PB) NE -Obtained by map of CAT temperature against PB plane (matrix). From these, it is possible to indirectly grasp the temperature of the CAT 6 before and when the engine is stopped based on the rotational speed NE and the pressure (PB) in the intake pipe 23 before the engine is stopped. When the internal combustion engine 1 stops, the temperature of the CAT 6 gradually decreases from the temperature immediately before the stop of the internal combustion engine 1 that can be grasped, as shown in FIG. Based on the elapsed time from the stop the internal combustion engine 1 by the timer 2c to the current (measurement time), the temperature of CAT6 the current in consideration of the temperature component of reduced can be indirectly grasped.

  In step S6, the active state determination unit 2b determines whether or not the CAT 6 is currently in an active state and the exhaust gas can be purified. Specifically, the temperature of CAT6 after grasping directly or indirectly, as shown in FIG. 3 (b), it is determined whether more than a predetermined temperature threshold value as a motoring permission temperature. When it is determined that the temperature of the CAT 6 is equal to or higher than the predetermined temperature threshold, and it is determined that the CAT 6 is currently in an active state and the exhaust can be purified (step S6, Yes), the process proceeds to step S7 and scavenging by motoring is performed. To do. If the temperature of CAT6 is not determined to be equal to or higher than the predetermined temperature threshold, and it is determined that CAT6 is not currently active and exhaust cannot be purified (No in step S6), the scavenging method is performed without performing the scavenging in step S7. Exit.

In step S7, the control device 2 drives the scavenging means 3 to perform scavenging by motoring. When motoring is performed, the rotational speed NE of the crankshaft 15 increases as shown in FIG. Due to the rotation (motoring) of the crankshaft 15, the fuel 22 is sent to the CAT 6 via the intake port 7 and the combustion chamber 13. The fuel 22 is exhausted (scavenged) outside the internal combustion engine 1 after being purified by the CAT 6. By this scavenging, as shown in FIG. 3E, the remaining HC can be reduced including the leaked fuel. Even if the engine start condition is satisfied and the internal combustion engine 1 is started, the remaining HC leaked fuel does not occur after scavenging, so the remaining HC level does not become higher than the normal operation level, and the emission at the start is The unburned component contained in can be reduced. The scavenging may be stopped when the scavenging time reaches a predetermined time (5 to 10 seconds), or when the rotation speed of the crankshaft 15 reaches a predetermined rotation speed (15 to 20 rotations). You may stop at any time.
In the embodiment, the port injection engine has been described as an example. However, in the direct injection engine, the fuel 22 leaks into the combustion chamber 13 instead of the intake port 7. It is clear that it can be applied.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Control apparatus 2a Fuel pressure grasping means 2b Active state determination means 2c Timer 3 Scavenging means (motor, starter)
4 Fuel Supply Means 5 Fuel Injection Valve 6 Purifier (CAT)
15 Crankshaft

Claims (2)

In a control apparatus for an internal combustion engine, comprising: a fuel injection valve provided for each cylinder of the internal combustion engine; a fuel supply means for supplying fuel in the fuel tank to the fuel injection valve; and a scavenging means for scavenging the combustion chamber.
A fuel pressure grasping means for grasping a fuel pressure applied to the fuel injection valve;
A control device for an internal combustion engine, which causes the scavenging means to perform scavenging when it is determined that the fuel pressure is reduced and is not more than a predetermined threshold value while the fuel supply by the fuel injection valve is stopped. Having an active state determining means for determining whether or not the purifying device for purifying the exhaust gas from the combustion chamber is in an active state;
2. The control device for an internal combustion engine according to claim 1, wherein when it is determined that the purifying device is not in an active state, execution of scavenging by the scavenging means is prohibited.

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