JP2009257196A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for a direct injection type internal combustion engine capable of discharging HC remaining in a cylinder due to oil seal leak from an injector nozzle after engine stop from an inside of the cylinder before engine start. <P>SOLUTION: An engine 1 is provided with a plasma irradiation device 500 irradiating plasma to a cylinder of which intake valve 12 or exhaust valve 14 opens after operation stop. Plasma is irradiated on fuel leaking from the injector 400 after engine stop and makes the same lighter to lighten specific gravity of unburned gas remaining in the cylinder. High concentration unburned gas is discharged to an outside of a combustion chamber 1a from the opened intake valve 12 or exhaust valve 14 to reduce fuel concentration in the cylinder. Consequently, over-rich at engine start can be inhibited and startability of the engine can be improved. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine. In particular, the present invention relates to a technique for improving startability of an internal combustion engine.

  As a control device for an internal combustion engine, there is a direct injection type fuel injection device that directly injects fuel into a cylinder, which is widely used in a vehicle engine or the like. 2. Description of the Related Art In recent years, direct injection type fuel injection devices have been required to have more complex control of fuel injection, refinement of fuel spray particle size, and the like due to demands such as improved fuel consumption and improved exhaust emissions. Therefore, since a higher fuel injection pressure is required, the fuel pressure supplied to the fuel injection device tends to increase.

  An injector used in a direct injection type fuel injection device is configured such that fuel is supplied at a high pressure from a fuel pump through a fuel pipe, and a needle provided inside the injector opens and closes an injection hole provided in a nozzle tip portion. In this configuration, the supply / stop of the high pressure fuel into the cylinder is controlled. When the engine is stopped, the injector stops supplying high-pressure fuel from the fuel pump, and the needle in the injector closes the injection hole, so that fuel is not supplied into the cylinder.

  However, the high pressure fuel supplied from the fuel pump during operation is stored in the injector and the fuel pipe immediately after the engine is stopped, and a high fuel pressure is applied to the injector. In addition, the oil tightness of the injector may decrease due to mass production variation of the injector, aging deterioration, and the like. Due to such a decrease in oil tightness, an oil tight leak may occur in which the fuel accumulated from the injector nozzle hole immediately after the engine stops leaks.

  When oil-tight leakage from the injector occurs, the leaked fuel is vaporized and stays in the cylinder, so that the cylinder of the stopped engine is filled with high-concentration unburned gas. Due to such an oil-tight leak from the injector, the fuel concentration in the cylinder of the stopped engine may become over-rich beyond the flammability limit, which causes problems such as deterioration of engine startability and exhaust emission deterioration at start-up. It is feared that this will occur.

  As a countermeasure against such a problem, a technology that discharges fuel injected into the cylinder from the exhaust valve to the outside of the cylinder while reducing the fuel pressure accumulated in the injector by injecting fuel immediately after the engine stops is patented. It is disclosed in Document 1. Further, for example, Patent Document 2 discloses a technique for diffusing unburned gas generated by oil tight leakage of an injector from the intake valve to the upstream of the throttle valve by opening the throttle valve when the engine is stopped. .

Japanese Patent Laying-Open No. 2005-069153 JP 2006-046187 A JP 2001-317360 A JP 2002-061556 A

  However, since the control device described in Patent Document 1 is not provided with a means for facilitating the discharge of the accumulated fuel injected into the cylinder immediately after the engine stops, the unburned gas staying in the cylinder is There may be a problem that the exhaust valve that has been opened cannot be completely removed and remains. Similarly, in the control device described in Patent Document 2, unburned gas remaining in the cylinder due to oil-tight leakage from the injector remains without being able to escape from the opened intake valve. There may be a problem.

  Therefore, the present invention provides a control device for an internal combustion engine that realizes good engine startability and exhaust emission by discharging unburned gas remaining in the engine cylinder after stopping to the outside of the cylinder with high efficiency. The purpose is to do.

  The control device for an internal combustion engine of the present invention that solves such a problem includes a fuel injection device that directly injects fuel into a cylinder, fuel supply means for supplying fuel to the fuel injection device, a purification catalyst in an exhaust passage, In the control device for an internal combustion engine, the detection means for detecting the stop of the internal combustion engine and the valve opening detection for detecting a cylinder in which at least one of the intake valve and the exhaust valve is open after the stop of the internal combustion engine And plasma irradiating means for irradiating the cylinder with plasma after the internal combustion engine is stopped, and the plasma irradiating means plasmas the cylinder in which at least one of the intake valve and the exhaust valve is open. (Claim 1). By adopting such a configuration, high concentration unburned gas staying in the cylinder of the internal combustion engine immediately after stopping can be discharged out of the cylinder with high efficiency, so that the startability and exhaust emission of the internal combustion engine are improved. Can do.

  The control device for an internal combustion engine of the present invention is provided with a plasma irradiation device in each cylinder, and by irradiating the fuel accumulated in the cylinder due to oil-tight leakage from the direct injection injector, Can be lightened into ingredients. Since the specific gravity of the fuel lightened by the plasma irradiation becomes lighter, the fuel rises in the cylinder and goes from the opened intake valve or exhaust valve to the outside of the cylinder. In this way, the fuel is lightened by irradiating the fuel leaking oil tightly into the cylinder to lighten the fuel, and the specific gravity of the remaining unburned gas is reduced, thereby discharging high concentration unburned gas out of the cylinder. Can help.

  As described above, since the unburned gas in each cylinder is discharged out of the cylinder, an ideal air-fuel ratio can be obtained at the next engine start. Therefore, it is possible to suppress deterioration of startability and exhaust emission, and achieve good engine start.

  In particular, the control device for an internal combustion engine of the present invention is supplied to the fuel injection device when detecting a stop of the internal combustion engine, and a fuel pressure detecting means for detecting a pressure of fuel supplied to the fuel injection device. Fuel pressure reducing means for reducing fuel pressure, and the plasma irradiating means irradiates plasma in the cylinder when the fuel pressure falls below a predetermined pressure. 2).

  By setting it as such a structure, since the fuel pressure concerning an injector and fuel piping immediately after an engine stop can be reduced, the oil-tight leak from an injector can be suppressed. Furthermore, the fuel that has leaked oil tightly until the fuel pressure is sufficiently lowered can be discharged out of the cylinder from the opened intake valve or exhaust valve by irradiating with plasma to lighten the fuel. Therefore, it is possible to further suppress the deterioration of the startability and the deterioration of the exhaust emission and achieve a good engine start.

  The control apparatus for an internal combustion engine according to the present invention further comprises throttle valve opening means for opening a throttle valve of the internal combustion engine, and the plasma irradiation means is configured to provide the intake valve when the throttle valve is opened. Plasma can be irradiated into the cylinder in which the valve is opened (Claim 3).

  With such a configuration, the fuel that leaks oil tightly from the injector is lightened by plasma irradiation, becomes unburned gas of low specific gravity, rises in the cylinder, and from the opened intake valve to the upstream of the throttle valve Spread. Therefore, the concentration of unburned gas staying in the cylinder can be reduced, and the next engine start can be made satisfactory.

  Furthermore, the control device for an internal combustion engine of the present invention includes catalyst temperature detection means for detecting the temperature of the purification catalyst, and the plasma irradiation means is configured to detect the temperature of the purification catalyst when the temperature of the purification catalyst exceeds a predetermined temperature. Plasma may be applied to the cylinder in which the exhaust valve is opened (Claim 4).

  With such a configuration, the fuel that has leaked oil tightly from the injector is lightened by plasma irradiation, becomes unburned gas with a low specific gravity, rises in the cylinder, and is exhausted from the opened exhaust valve. It heads for the purification catalyst provided in the passage. Since the purification catalyst is in the active temperature range, the unburned gas is decomposed into a clean gas by coming into contact with the purification catalyst and then discharged to the outside. Therefore, it is possible to prevent deterioration of exhaust emission immediately after stopping while effectively discharging unburned gas from the cylinder after stopping the engine to the exhaust side.

  The control device for an internal combustion engine of the present invention includes a fuel injection device that directly injects fuel into the cylinder, a fuel supply means for supplying the fuel to the fuel injection device, and a purification catalyst in the exhaust passage. In the control device for an internal combustion engine, detection means for detecting stop of the internal combustion engine, and valve opening detection means for detecting that at least one of the intake valve and the exhaust valve is opened after the stop of the internal combustion engine, Air injection means for injecting air into the cylinder after the internal combustion engine is stopped, and the air injection means injects air when at least one of the intake valve and the exhaust valve is open. (Claim 5).

  In the control device for an internal combustion engine of the present invention, an air injection device is provided in each cylinder. As a result, air is injected into the fuel retained in the cylinder due to oil-tight leakage from the direct injection injector, and unburned gas in the cylinder is discharged outside the cylinder from the opened intake valve or exhaust valve by the injection force. be able to. Thus, by injecting air to the high-concentration unburned gas generated in the cylinder due to oil-tight leakage from the injector, it is possible to help discharge the unburned gas out of the cylinder.

  The control device for an internal combustion engine of the present invention is supplied to the fuel injection device when detecting a stop of the internal combustion engine, and a fuel pressure detection means for detecting a pressure of fuel supplied to the fuel injection device. Fuel pressure reducing means for reducing the fuel pressure, and the air injection means injects air into the cylinder when the fuel pressure falls below a predetermined pressure. 6).

  By setting it as such a structure, since the fuel pressure concerning the fuel piping and injector immediately after an engine stop can be reduced, the oil-tight leak from an injector can be suppressed. Furthermore, the fuel leaking oil tightly until the fuel pressure is sufficiently lowered can be discharged out of the cylinder from the opened intake valve or exhaust valve by injecting air. Therefore, it is possible to further suppress the deterioration of the startability and the deterioration of the exhaust emission and achieve a good engine start.

  Furthermore, the control device for an internal combustion engine of the present invention includes catalyst temperature detection means for detecting the temperature of the purification catalyst, and the air injection means is configured to detect the temperature of the purification catalyst when the temperature of the purification catalyst exceeds a predetermined temperature. Air may be injected into the cylinder in which the exhaust valve is opened (Claim 7).

  With such a configuration, the fuel that has leaked oil tightly from the injector travels from the opened exhaust valve to the purification catalyst provided in the exhaust passage by the injection force of air. Since the purification catalyst is in the active temperature range, the unburned gas is decomposed into a clean gas by coming into contact with the purification catalyst and then discharged to the outside. Therefore, it is possible to prevent deterioration of exhaust emission immediately after stopping while effectively discharging unburned gas from the cylinder after stopping the engine to the exhaust side.

  The control device for an internal combustion engine according to the present invention includes a plasma irradiation means for irradiating plasma to a cylinder in which either one of the intake valve and the exhaust valve is opened after the internal combustion engine is stopped. By lightening the leaked fuel and reducing the specific gravity of the unburned gas remaining in the cylinder, it is possible to help discharge the high concentration unburned gas out of the cylinder. Therefore, an ideal air-fuel ratio can be obtained at the next engine start, and a good engine start can be achieved.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing a schematic configuration of an engine 1 incorporating a control device for an internal combustion engine according to the present embodiment. FIG. 1 shows only the configuration of one cylinder of the engine.

  The engine 1 is a multi-cylinder engine mounted on a vehicle, and each cylinder includes a piston 2 constituting a combustion chamber 1a. The piston 2 of each combustion chamber 1a is connected to the shaft of the crankshaft 3 which is an output shaft via a connecting rod 4, and the reciprocating motion of each piston 2 is converted into rotation of the crankshaft 3 by the connecting rod 4. The

  A crank angle sensor 5 is disposed near the axis of the crankshaft 3. The crank angle sensor 5 is configured to detect the rotation angle of the three crankshaft axes, and outputs the detection result to the ECU 100. Thereby, ECU100 can acquire the information regarding a crank angle. Further, a crank sprocket 6 is connected to one end of the crankshaft 3. The crank sprocket 6 rotates at the same cycle as the crankshaft 3. As the crank sprocket 6, a known sprocket having a plurality of teeth arranged on the outer periphery can be used. The crank sprocket 6 is meshed with a pinion gear of a starter motor 7 that is started when the engine 1 is started, and the engine 1 is cranked by the rotation of the ring gear accompanying the starter motor 7 being started.

  Connected to the combustion chamber 1a of each cylinder are an intake port 8 communicating with the combustion chamber 1a and an intake passage 9 connected to the intake port 8 and leading intake air from the intake port 8 to the combustion chamber 1a. . Further, each cylinder of the combustion chamber 1a is connected to an exhaust port 10 communicating with the combustion chamber 1a and an exhaust passage 11 for guiding the exhaust gas generated in the combustion chamber 1a to the outside of the engine. Further, the exhaust passages 11 connected to the respective cylinders merge on the downstream side to form one merged exhaust passage 300.

  A plurality of intake valves and exhaust valves are provided corresponding to the intake passage and exhaust passage of the combustion chamber 1a of each cylinder. FIG. 1 shows one intake passage, one exhaust passage, one intake valve, and one exhaust valve. An intake valve 12 is disposed in each intake port 8 of the combustion chamber 1a, and an intake camshaft 13 for opening and closing the intake valve 12 is disposed. Further, an exhaust valve 14 is disposed at each exhaust port 10 of the combustion chamber 1a, and an exhaust camshaft 15 for opening and closing the exhaust valve 14 is disposed.

  The intake valve 12 and the exhaust valve 14 are opened and closed by the rotation of the intake camshaft 13 and the exhaust camshaft 15 to which the rotation of the crankshaft 3 is transmitted by a coupling mechanism (for example, a timing belt, a timing chain, etc.). 10 and the combustion chamber 1a are communicated and blocked. The phase of each intake valve and exhaust valve is expressed with reference to the crank angle.

  The rotational phase of intake camshaft 13 is detected by intake cam angle sensor 16 and output to ECU 100. Thus, the ECU 100 can acquire the phase of the intake camshaft 13 and the phase of each intake valve. The intake cam angle sensor 16 corresponds to valve opening detecting means for detecting that the intake valve 12 is opened. Further, the phase of the intake camshaft 13 is expressed with reference to the crank angle.

  Further, the rotational phase of the exhaust camshaft 15 is detected by the exhaust cam angle sensor 17 and output to the ECU 100. Thereby, the ECU 100 can acquire the phase of the exhaust camshaft 15 and the phase of each exhaust valve. The exhaust cam angle sensor 17 corresponds to valve opening detecting means for detecting that the exhaust valve 14 is opened. Further, the phase of the exhaust camshaft 15 is expressed with reference to the crank angle.

  An air flow meter 18 for detecting the amount of intake air passing through the intake passage 9 is installed in the intake passage 9 of the engine 1. A throttle valve 19 and a throttle position sensor 20 are installed in the intake passage 9. The air flow meter 18 and the throttle position sensor 20 output the respective detection results to the ECU 100. Thereby, the ECU 100 can recognize the intake air amount sucked into the intake port 8 and the combustion chamber 1a.

  Each cylinder of the engine 1 is equipped with an injector 400. High-pressure fuel supplied from a fuel pump (not shown) through the fuel pipe 401 is injected and supplied to the combustion chamber 1 a in the engine cylinder by the injector 400 according to an instruction from the ECU 100. The ECU 100 determines the fuel injection amount and the injection timing based on the intake air amount from the air flow meter 18 and the throttle position sensor 20 and the cam shaft rotation phase information from the intake cam angle sensor 16 and sends a signal to the injector 400. Injector 400 injects high-pressure fuel into combustion chamber 1a at the instructed fuel injection amount / injection timing in accordance with a signal from ECU 100. The high-pressure injected fuel is atomized and mixed with the intake air supplied from the intake valve 12 to become a mixed gas suitable for combustion of the engine 1. The leaked fuel from the injector 400 is returned to the fuel tank (not shown) through the relief pipe. The injector 400 corresponds to the fuel injection device of the present invention, and the fuel pump, the fuel pipe 401 and the fuel tank correspond to the fuel supply means. The fuel pipe 401 is provided with a fuel pressure sensor 402 for detecting the fuel pressure in the fuel pipe, and corresponds to the fuel pressure detecting means of the present invention.

  The combustion chamber 1 a of each cylinder is provided with a spark plug 21, and the ignition timing of the spark plug 21 is adjusted by an igniter 22. The mixed gas flowing in from the intake port 8 is compressed in the combustion chamber 1 a by the upward movement of the piston 2. The ECU 100 determines the ignition timing based on the position of the piston 2 from the crank angle sensor 5 and the cam shaft rotation phase information from the intake cam angle sensor 16 and sends a signal to the igniter 22. The igniter 22 energizes the spark plug 21 with the electric power from the battery 200 at the instructed ignition timing in accordance with a signal from the ECU 100. The spark plug 21 is ignited by electric power from the battery 200, ignites the compressed mixed gas, expands the inside of the combustion chamber 1a, and lowers the piston 2. By changing this to the axial rotation of the crankshaft 3 via the connecting rod 4, the engine 1 obtains power. When the exhaust valve 14 is opened, the exhaust gas after combustion joins in the merged exhaust passage 300 through the exhaust port 10 and the exhaust passage 11, passes through the purification catalyst 301, and is discharged to the outside of the engine.

  The exhaust passages 11 of the cylinders merge downstream to form a combined exhaust passage 300, and a purification catalyst 301 is provided at the end of the combined exhaust passage 300. The purification catalyst 301 is used to purify the exhaust gas of the engine 1. For example, a three-way catalyst, a NOx occlusion reduction type catalyst, or the like is applied, and a plurality of these are combined depending on the engine exhaust amount, the use area, and the like. Sometimes installed. The purification catalyst 301 is provided with a catalyst temperature sensor 302. The ECU 100 can recognize the temperature of the purification catalyst 301 by detecting a signal from the catalyst temperature sensor 302 and determine whether or not the purification catalyst is in the active temperature range. Note that the catalyst temperature sensor 302 of this embodiment corresponds to catalyst temperature detection means.

  Each cylinder is provided with a plasma irradiation device 500, and electric power is supplied from the battery 200 in accordance with a signal from the ECU 100 to irradiate the cylinder with plasma. The plasma irradiation device 500 is, for example, in the vicinity of the nozzle hole of the injector 400 and does not interfere with the sliding piston 2 in order to effectively irradiate the oil leaked from the injector 400 with light and reduce the lightness. It is desirable to be provided. In addition, the plasma irradiation apparatus 500 of a present Example is corresponded to a plasma irradiation means.

  Plasma means a material state in which two or more kinds of charged particles having positive and negative charges that move freely coexist. The plasma irradiated by the plasma irradiation apparatus 500 is generated by causing electrons generated by the discharge between the electrodes to collide with the gas and changing the gas into positive ions and negative ions. As the discharge mode, arc discharge, corona discharge, barrier discharge, or the like can be applied. As the discharge electrode, a conductive material or a semiconductor material can be used. In particular, a high melting point metal material such as tungsten can be used. Nitrogen, air, argon, recirculated exhaust gas (EGR gas), etc. are mentioned as gas used as plasma. Here, especially when air or EGR gas is turned into plasma, OH radicals and O radicals can be generated. These radicals can promote the lightening of the fuel, and can bind to the end of the molecular chain of the cut fuel to prevent the generation of unsaturated hydrocarbons, thereby suppressing the generation of soot. In addition, since air and EGR gas are obtained from outside air or exhaust, a tank for storing gas to be supplied to the plasma irradiation apparatus 500 is not necessary.

  The ECU 100 is a computer including a CPU (Central Processing Unit) that performs arithmetic processing, a ROM (Read Only Memory) that stores programs and the like, and a RAM (Random Access Memory) that stores data and the like. ECU 100 includes crank angle sensor 5, cam angle sensors 16 and 17, air flow meter 18, throttle position sensor 20, catalyst temperature sensor 302, fuel pressure sensor 402, operation of injector 400, ignition timing of spark plug 21, and plasma irradiation device 500. The operation of the engine 1 such as operation and detection of ON / OFF of the ignition switch 50 is integratedly controlled. The ECU 100 corresponds to detection means for detecting the stop of the internal combustion engine.

  Next, the operation of the engine 1 will be described along the control flow of the ECU 100. FIG. 2 is an example of a flowchart showing the processing of the ECU 100. The control of the ECU 100 is started when there is a request to stop the engine 1, that is, when the ignition switch 50 is turned off.

  First, in step S1, the ECU 100 determines whether or not the fuel pressure in the fuel pipe 401 is equal to or lower than a predetermined pressure P based on information from the fuel pressure sensor 402. Here, as the pressure P, a fuel pressure that is low enough to prevent oil-tight leakage from the injector 400 is applied. If the determination result in step S1 is YES, that is, if the fuel pressure in the fuel pipe 401 is equal to or lower than P, the process proceeds to step S5. If the determination result in step S1 is NO, that is, if the fuel pressure in the fuel pipe 401 is a pressure exceeding P, the process proceeds to step S2.

  The ECU 100 opens the throttle valve 19 in step S2, secures a diffusion passage so that unburned gas in the cylinder can diffuse to the upstream side of the throttle valve, and then proceeds to step S3. Subsequently, in step S3, the ECU 100 detects a cylinder (referred to as cylinder I) in which the intake valve 12 is opened based on information from the intake cam angle sensor 16, and proceeds to step S4. In step S4, the ECU 100 instructs the injector 400 provided in the cylinder I to inject the accumulated fuel. After the process of step S4, the ECU 100 returns to step S1 again and injects the pressure-accumulated fuel into the injector 400 of the cylinder I until the fuel pressure in the fuel pipe 401 drops below P, that is, until the determination result in step S1 becomes YES. Instruct. By this process, the fuel pressure applied to the injector 400 immediately after the engine 1 is stopped can be lowered until the fuel pressure becomes equal to or lower than the fuel pressure P at which oil-tight leakage from the injector 400 does not occur. If the determination result in step S1 is YES, the ECU 100 proceeds to step S5 and instructs the injector 400 to stop the injection of the accumulated fuel into the cylinder I.

  The ECU 100 proceeds to step S6 after the process of step S5. In step S6, the ECU 100 instructs the plasma irradiation device 500 in the cylinder I to irradiate the cylinder I with plasma. By this plasma irradiation, the fuel injected into the cylinder I and the oil-tight leaked fuel are lightened and light in specific gravity and diffused from the intake valve 12 opened in the cylinder I to the upstream of the throttle valve 19. . As described above, the control device for the internal combustion engine of the present embodiment is lightened by irradiating the fuel existing in the cylinder after the engine is stopped to reduce the specific gravity of the unburned gas remaining in the cylinder. Further, it is possible to facilitate discharging the high-concentration unburned gas out of the cylinder (see FIG. 3). Subsequently, the ECU 100 proceeds to step S7 after the process of step S6.

  In step S7, ECU 100 determines whether or not a predetermined time T seconds has elapsed. Here, as the predetermined time T, a sufficient time considered to be necessary for the lightened fuel to diffuse to the upstream side of the throttle valve 19 is applied. If the determination in step S7 is yes, the ECU 100 proceeds to the next step S8.

  The ECU 100 stops the plasma irradiation to the cylinder I in step S8, and proceeds to step S9. In step S9, the ECU 100 closes the opened throttle valve 19 and ends the control process.

  As described above, the engine 1 reduces the fuel pressure applied to the injector 400 by injecting the fuel accumulated in the injector 400 and the fuel pipe 401 into the cylinder I with the intake valve 12 opened immediately after the engine is stopped. Oil tight leakage can be suppressed. Furthermore, the engine 1 can irradiate plasma into the cylinder I to lighten the unburned gas and diffuse it to the upstream side of the throttle valve 19 to reduce the fuel concentration in the cylinder. Therefore, overrich at the time of engine start can be suppressed, and startability of the engine can be improved.

  Next, a second embodiment of the present invention will be described. FIG. 4 is an example of a flowchart showing processing of the ECU 100 mounted on the engine 60 of the embodiment. In addition, about the process similar to Example 1, the same reference number is attached | subjected in drawing. Similar to the first embodiment, the control of the ECU 100 is started when the engine 60 is requested to be stopped, that is, when the ignition switch 50 is turned off.

  First, in step S1, the ECU 100 determines whether or not the fuel pressure in the fuel pipe 401 is equal to or lower than a predetermined pressure P based on information from the fuel pressure sensor 402. If the determination result in step S1 is YES, that is, if the fuel pressure in the fuel pipe 401 is equal to or lower than P, the process proceeds to step S13. If the determination result in step S1 is NO, that is, if the fuel pressure in the fuel pipe 401 is a pressure exceeding P, the process proceeds to step S10.

  In step S10, the ECU 100 determines whether or not the purification catalyst 301 is in the activation temperature range based on information from the catalyst temperature sensor 302. Here, the active temperature range is a temperature range in which the purification catalyst 301 installed in the merged exhaust passage 300 can exhibit the required catalyst performance. The activation temperature range of the purification catalyst 301 is in a different range depending on the material and the composition, but can be set to 300 ° C. to 850 ° C., for example. If the determination result in step S10 is NO, that is, if the temperature of the purification catalyst 301 is not in the active temperature range, the ECU 100 proceeds to step S2 of the first embodiment and continues the processing of the first embodiment as it is. If the determination result in step S10 is YES, that is, if the temperature of the purification catalyst 301 is in the activation temperature range, the process proceeds to step S11.

  In step S11, the ECU 100 detects a cylinder (referred to as cylinder J) in which the exhaust valve 14 is open based on information from the exhaust cam angle sensor 17, and proceeds to step S12. In step S12, the ECU 100 instructs the injector 400 provided in the cylinder J to inject the accumulated fuel. After the process of step S12, the ECU 100 returns to step S1 again and injects the pressure-accumulated fuel into the injector 400 of the cylinder J until the fuel pressure in the fuel pipe 401 drops below P, that is, until the determination result in step S1 becomes YES. Instruct. By this process, the fuel pressure applied to the injector 400 immediately after the engine 60 is stopped can be lowered until the fuel pressure P becomes equal to or lower than the fuel pressure P at which oil-tight leakage from the injector 400 does not occur. If the decision result in the step S1 is YES, the ECU 100 proceeds to a step S13 and instructs the injector 400 to stop the injection of the accumulated fuel into the cylinder J.

  The ECU 100 proceeds to step S14 after the process of step S13. In step S14, the ECU 100 instructs the plasma irradiation device 500 in the cylinder J to irradiate the cylinder J with plasma. By this plasma irradiation, the fuel injected into the cylinder J and the oil-tight leaked fuel are lightened and have a reduced specific gravity. The exhaust valve 14 that rises in the cylinder J and is opened to the exhaust passage 11, the combined exhaust passage 300. Then, after passing through the purification catalyst 301, it is discharged to the outside of the engine 60. As described above, the control device for the internal combustion engine of the present embodiment is lightened by irradiating the fuel existing in the cylinder after the engine is stopped to reduce the specific gravity of the unburned gas remaining in the cylinder. Further, it is possible to help discharge a high concentration of unburned gas out of the cylinder. Furthermore, when unburned gas is discharged outside the engine, it is decomposed into clean gas by contacting the purification catalyst in the active temperature range, so that deterioration of exhaust emission immediately after stopping can be suppressed. (See FIG. 5). Subsequently, the ECU 100 proceeds to step S15 after the process of step S14.

  In step S15, ECU 100 determines whether or not a predetermined time U seconds has elapsed. Here, as the predetermined time U, a sufficient time considered to be necessary for the lightened fuel to diffuse to the downstream of the purification catalyst 301 installed in the merged exhaust passage 300 is applied. If the determination in step S15 is yes, the ECU 100 proceeds to the next step S16.

  In step S16, the ECU 100 stops the plasma irradiation to the cylinder J and ends the control process.

  As described above, the engine 60 of this embodiment can reduce the fuel concentration in the cylinder while suppressing oil-tight leakage from the injector 400 as well as the first embodiment. It can be decomposed into clean gas and discharged outside the engine 60. Therefore, it is possible to prevent deterioration of exhaust emission immediately after the stop while improving the startability of the engine.

  Further, a third embodiment of the present invention will be described. FIG. 6 is an explanatory diagram showing a schematic configuration of one cylinder of the engine 70 incorporating the control device for the internal combustion engine of the present embodiment. The engine 70 of the present embodiment has substantially the same configuration as the engine 1 of the first embodiment, but includes an air injection device 600 in the cylinder instead of the plasma irradiation device 500 provided in the engine 1. Further, it is different from the engine 1 in that an air pump 601 is further provided. The air injection device 600 and the air pump 601 correspond to the air injection means of the present invention.

  The engine 1 of the first embodiment is lightened by irradiating plasma to the fuel retained in the cylinder due to oil-tight leakage from the direct injection injector, and reducing the specific gravity of the remaining unburned gas, thereby reducing the high concentration of unburned gas. It helps to discharge the fuel gas out of the cylinder. On the other hand, the engine 70 of the present embodiment includes an air injection device 600 in each cylinder, injects air supplied from the air pump 601 into the cylinder, and unburned gas in the cylinder by the injection force. Is discharged from the opened intake valve or exhaust valve to the outside of the cylinder. Thus, by injecting air to the high-concentration unburned gas generated in the cylinder due to oil-tight leakage from the injector, it is possible to help discharge the unburned gas out of the cylinder.

  An air injection device 600 provided in each cylinder injects air into the cylinder according to a signal from the ECU 100. The air injection device 600 is provided, for example, in the vicinity of the injection hole of the injector 400 and in a position where it does not interfere with the sliding piston 2 in order to effectively discharge the oil leaked from the injector 400 to the outside of the cylinder. It is desirable. The air pump 601 is driven by electric power from the battery 200 and supplies air to the air injection device 600. The air pump 601 may be set not to be driven when the vehicle is running, that is, when the engine 70 is at a high speed, but to start driving immediately before the vehicle is stopped, that is, during idle operation. Good.

  FIG. 7 is an example of a flowchart showing the processing of the ECU 100 mounted on the engine 70. The ECU 100 of the engine 70 controls the following steps S17 to S19 after step S13 while performing the control of steps S1 to S13 of the engine 60 of the second embodiment. Therefore, since the control from step S1 to step S13 is the same as that of the engine 60 of the second embodiment, detailed description thereof is omitted. In this case, steps S6, S7, and S8 after step S2 are replaced with steps S17, S18, and S19 described later.

  After step S13, the ECU 100 proceeds to step S17. In step S17, the ECU 100 instructs the air injection device 600 in the cylinder J to inject air into the cylinder J. The fuel injected into the cylinder J and the oil-tight leaked fuel by the injection force of the air injection passes through the exhaust passage 11, the combined exhaust passage 300, and the purification catalyst 301 from the exhaust valve 14 opened from the inside of the cylinder J. The engine 70 is discharged to the outside. As described above, the control device for the internal combustion engine according to the present embodiment injects air into the fuel existing in the cylinder after the engine is stopped, and discharges high-concentration unburned gas outside the cylinder by the injection force. Can help. Subsequently, the ECU 100 proceeds to step S18 after the process of step S17.

  In step S18, ECU 100 determines whether or not a predetermined time V seconds has elapsed. Here, the predetermined time V is a time sufficient for the fuel accumulated in the cylinder by the air injection force to be diffused to the downstream of the purification catalyst 301 installed in the merged exhaust passage 300. If the determination in step S18 is yes, the ECU 100 proceeds to the next step S19.

  In step S19, the ECU 100 stops driving the air pump 601 while stopping air injection into the cylinder J, and ends the control process.

  As described above, the engine 70 of this embodiment can reduce the fuel concentration in the cylinder while suppressing oil-tight leakage from the injector 400 as in the first embodiment. Further, similarly to the second embodiment, the unburned gas can be decomposed into a clean gas and discharged to the outside of the engine 70. Therefore, it is possible to prevent deterioration of exhaust emission immediately after the stop while improving the startability of the engine.

  The above embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to these, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

  For example, as shown in the flowchart of the processing of the ECU 100 shown in FIG. 8, the plasma irradiation to the cylinder I is set to be performed when the internal combustion engine is started, that is, to start when the ignition switch 50 is turned on. You can also. As a result, the fuel concentration in the cylinder immediately before the engine is started can be reduced, so that the overrich at the time of starting the engine can be further suppressed.

  In addition, in the control flow of the ECU 100 according to the first embodiment, step S6 is set between step S3 and step S4 in order to set the timing of starting plasma irradiation into the cylinder before injecting the fuel accumulated in the injector. Can also be set. As a result, the pressure-accumulated fuel injected from the injector 400 is always injected into the plasma atmosphere, so that the fuel can be made lighter by plasma more easily.

1 is an explanatory diagram showing a schematic configuration of an engine in which a control device for an internal combustion engine according to a first embodiment is incorporated. The flow of the control which ECU of Example 1 performs is shown. 1 is an explanatory diagram illustrating a schematic configuration of one cylinder of an engine according to Embodiment 1. FIG. The flow of control which ECU of Example 2 performs is shown. FIG. 5 is an explanatory diagram showing a schematic configuration of one cylinder of an engine according to a second embodiment. FIG. 5 is an explanatory diagram showing a schematic configuration of one cylinder of an engine according to a third embodiment. The flow of the control which ECU of Example 3 performs is shown. The flow of the control which ECU performs is shown.

Explanation of symbols

1 Engine 1a Combustion chamber 2 Piston 3 Crankshaft 11 Exhaust passage 12 Intake valve 13 Intake camshaft 14 Exhaust valve 15 Exhaust camshaft 16 Intake cam angle sensor (valve opening detecting means)
17 Exhaust cam angle sensor (Valve opening detection means)
19 Throttle valve 50 Ignition switch 100 ECU (detection means for detecting stop of internal combustion engine)
200 Battery 300 Junction exhaust passage 301 Purification catalyst 302 Catalyst temperature sensor (catalyst temperature detection means)
400 injector (fuel injection device)
401 Fuel piping 402 Fuel pressure sensor (fuel pressure detection means)
500 Plasma irradiation device (plasma irradiation means)

Claims (7)

In a control device for an internal combustion engine comprising a fuel injection device that directly injects fuel into a cylinder, fuel supply means for supplying fuel to the fuel injection device, and a purification catalyst in an exhaust passage,
Detecting means for detecting a stop of the internal combustion engine;
A valve opening detecting means for detecting a cylinder in which at least one of an intake valve and an exhaust valve is opened after the internal combustion engine is stopped;
Plasma irradiation means for irradiating plasma into the cylinder after the internal combustion engine is stopped,
The control apparatus for an internal combustion engine, wherein the plasma irradiation means irradiates plasma to the cylinder in which at least one of the intake valve and the exhaust valve is open. The control device according to claim 1,
Fuel pressure detection means for detecting the pressure of the fuel supplied to the fuel injection device;
Fuel pressure reducing means for reducing the fuel pressure supplied to the fuel injection device when detecting the stop of the internal combustion engine;
The control apparatus for an internal combustion engine, wherein the plasma irradiation means irradiates plasma into the cylinder when the fuel pressure falls below a predetermined pressure. The control device according to claim 1 or 2,
Comprising throttle valve opening means for opening the throttle valve of the internal combustion engine;
The control apparatus for an internal combustion engine, wherein the plasma irradiation means irradiates plasma into the cylinder in which the intake valve is opened when the throttle valve is opened. The control device according to claim 1 or 2,
Comprising catalyst temperature detection means for detecting the temperature of the purification catalyst;
The control apparatus for an internal combustion engine, wherein the plasma irradiation means irradiates plasma into the cylinder in which the exhaust valve is opened when the temperature of the purification catalyst exceeds a predetermined temperature. In a control device for an internal combustion engine comprising a fuel injection device that directly injects fuel into a cylinder, fuel supply means for supplying fuel to the fuel injection device, and a purification catalyst in an exhaust passage,
Detecting means for detecting a stop of the internal combustion engine;
Valve opening detecting means for detecting that at least one of the intake valve and the exhaust valve is opened after the internal combustion engine is stopped;
Air injection means for injecting air into the cylinder after the internal combustion engine is stopped;
The control apparatus for an internal combustion engine, wherein the air injection means injects air when at least one of the intake valve and the exhaust valve is open. The control device according to claim 5,
Fuel pressure detection means for detecting the pressure of the fuel supplied to the fuel injection device;
Fuel pressure reducing means for reducing the fuel pressure supplied to the fuel injection device when detecting the stop of the internal combustion engine;
The control apparatus for an internal combustion engine, wherein the air injection means injects air into the cylinder when the fuel pressure falls below a predetermined pressure. The control device according to claim 5 or 6,
Comprising catalyst temperature detection means for detecting the temperature of the purification catalyst;
The control apparatus for an internal combustion engine, wherein the air injection means injects air into the cylinder in which the exhaust valve is opened when the temperature of the purification catalyst exceeds a predetermined temperature.

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