JP2010096033A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine which can suppress deteriorations of engine oil and of emission ascribable to the storing of blow-by gas in a crank case at engine stop. <P>SOLUTION: The internal combustion engine 100 is provided with a blow-by gas recirculation device 50 for recirculating blow-by gas in a crank case 1a to an intake manifold 10 and an exhaust emission control catalyst 22 for purifying exhaust. The blow-by gas recirculation device 50 includes an electronic control type PCV valve 53 for adjusting a recirculation amount of the blow-by gas. An electronic control device 60 of the internal combustion engine 100 maintains an opening state of the PCV valve 53 when fuel cut is executed on the basis of a command for stopping the internal combustion engine 100. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine including a blow-by gas recirculation device that recirculates blow-by gas in a crankcase to an intake passage.

Gases that leak from the combustion chamber to the crankcase during the combustion stroke of the internal combustion engine, so-called blow-by gas, contain components such as hydrocarbons (HC) and nitrogen oxides (NOx). When NOx contained in such blow-by gas comes into contact with the engine oil in the crankshaft, sludge is generated and the engine oil is deteriorated. Therefore, in order to suppress such inconvenience, as described in Patent Document 1, for example, a blow-by gas recirculation device that recirculates the blow-by gas to the intake passage has been proposed. The blow-by gas recirculation device described in this document is a breather passage that connects a crankcase and an intake passage of an internal combustion engine, and a PCV that is provided in the breather passage and opens based on a pressure difference between the crankcase and the intake passage. It has a valve. In an internal combustion engine employing such a blow-by gas recirculation device, the PCV valve opens based on the pressure difference between the crankcase and the intake passage, so that the blow-by gas in the crankcase is introduced into the combustion chamber through the intake passage and re-combustion can do.
JP 2006-250080 A

  By circulating the blow-by gas through the intake passage in this way, it becomes possible to suppress the deterioration of the engine oil caused by the blow-by gas. However, since the above-described PCV valve opens based on the pressure difference between the crankcase and the intake passage, the PCV valve may not be opened because the pressure difference is low, for example, during the operation period immediately before the engine stops. . Thus, if the PCV valve does not open during the operation period immediately before the engine stops, blow-by gas generated during the operation period is stored in the crankcase, and engine oil may be deteriorated when the engine is stopped. Further, when blow-by gas is stored in the crankcase when the engine is stopped in this way, when the engine is restarted after the engine is once in a cold state, the blow-by gas stored in the crank case is not burned in the combustion chamber. It may be discharged into the exhaust system. Here, an exhaust purification catalyst for purifying HC and NOx is usually provided in the exhaust system of the internal combustion engine. However, since this exhaust purification catalyst is not activated in the cold state of the engine, HC and NOx contained in the gas are discharged into the atmosphere as they are, leading to worsening of emissions.

  The present invention has been made in view of such circumstances, and an object thereof is an internal combustion engine capable of suppressing deterioration of engine oil and emission caused by storing blowby gas in a crankcase when the engine is stopped. It is to provide an engine control device.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
The invention according to claim 1 is a control device for an internal combustion engine, comprising: a blow-by gas recirculation device that recirculates the blow-by gas in the crankcase to the intake passage; and an exhaust purification catalyst that is provided in the exhaust system and purifies exhaust gas. The blow-by gas recirculation device is provided with an electronically controlled blow-by gas rectifying valve that adjusts the flow rate of the blow-by gas, and when the fuel cut is executed based on a command to stop the internal combustion engine, The gist of the invention is to include an opening degree maintaining means for maintaining the gas rectifying valve in the open state.

  According to this configuration, since the blow-by gas circulation device includes the electrically driven blow-by gas rectifying valve that adjusts the circulation flow rate of the blow-by gas, for example, the rectification that opens based on the pressure difference between the crankcase and the intake passage. Compared with the case where a blowby gas recirculation device including a valve is employed, the flow rate of blowby gas can be freely adjusted without depending on the pressure difference. Further, when the fuel cut is executed based on a command to stop the internal combustion engine, the blow-by gas circulation flow rate can be maintained by maintaining the blow-by gas rectifying valve in the open state. Thereby, before the internal combustion engine stops, discharge of blow-by gas in the crankcase can be secured, and storage of blow-by gas in the crankcase when the internal combustion engine stops can be suppressed. Here, since the exhaust purification catalyst provided in the exhaust system is activated between the time when the fuel cut is performed and the time when the internal combustion engine is stopped, HC and NOx contained in the blow-by gas can be purified. , The same component can be prevented from being discharged into the atmosphere. Therefore, according to the above configuration, it is possible to suppress the deterioration of the engine oil and the emission caused by the blow-by gas being stored in the crankcase when the engine is stopped.

  Note that, as described in claim 2, it is desirable to employ a configuration in which the blow-by gas rectifying valve is maintained in a fully opened state when a fuel cut is performed based on a command to stop the internal combustion engine. . By adopting such a configuration, it is possible to promote the exhaust of blow-by gas in the crankcase as much as possible before the internal combustion engine stops.

  According to a third aspect of the present invention, in the control device for an internal combustion engine according to the first or second aspect, the opening degree maintaining means is on condition that the rotational speed of the internal combustion engine is equal to or higher than a predetermined speed. The gist of the invention is to maintain the blow-by gas rectifying valve in an open state.

  When the opening of the blow-by gas rectification valve is constant, the lower the rotational speed of the internal combustion engine, the lower the flow rate of the blow-by gas, and the lower the efficiency of exhausting the blow-by gas in the crankcase by the blow-by gas circulation device Will come to do.

  In the above configuration, the blow-by gas rectifying valve is maintained in the open state by the opening degree maintaining means on condition that the rotational speed of the internal combustion engine is equal to or higher than a predetermined speed. As described above, the control for discharging the blow-by gas is executed only when the rotational speed of the internal combustion engine is high, that is, when the efficiency of discharging the blow-by gas in the crankcase is high. Will be able to.

  According to a fourth aspect of the present invention, in the control device for an internal combustion engine according to any one of the first to third aspects, the control is performed after the control of the blow-by gas rectifying valve by the opening degree maintaining means is completed. And a stop opening degree setting means for setting the opening degree of the blowby gas rectification valve when the internal combustion engine is stopped to a value smaller than the opening degree of the blowby gas rectification valve set in step 1. To do.

  While the internal combustion engine is stopped, HC volatilized from engine oil in the crankcase may enter the combustion chamber through the intake passage. The HC entering the combustion chamber in this way is not combusted during the cranking period at the next engine start and is discharged to the atmosphere, which may deteriorate the emission.

  In this regard, according to the above configuration, by setting the opening of the blow-by gas rectifying valve to a small value when the internal combustion engine is stopped, the HC volatilized from the engine oil in the crankcase when the internal combustion engine is stopped is taken in. It is possible to suppress entry into the combustion chamber through the passage, and it is possible to suppress deterioration of emissions resulting from this.

  According to a fifth aspect of the present invention, in the control apparatus for an internal combustion engine according to any one of the first to third aspects, the blow-by gas adjustment by the outside air temperature detecting means for detecting the outside air temperature and the opening degree maintaining means. When the outside air temperature detected by the outside air temperature detecting means is lower after the control for the flow valve is completed, the opening degree setting at the time of stop is set to increase the opening degree of the blow-by gas rectifying valve when the internal combustion engine is stopped. Providing a means.

  When the outside air temperature is low, the blow-by gas rectifying valve may be frozen and fixed after the internal combustion engine is stopped. Here, the smaller the opening of the blow-by gas rectifying valve is, that is, the closer the distance between the valve body of the blow-by gas rectifying valve and the valve seat is, the more likely that the rectifying valve is frozen and fixed.

  In this regard, according to the above-described configuration, the lower the outside air temperature detected by the outside air temperature detecting means when the internal combustion engine is stopped, the larger the opening of the blow-by gas rectifying valve when the internal combustion engine is stopped. Even when the outside air temperature is low, it is possible to suitably suppress the occurrence of freeze fixation of the blow-by gas rectifying valve after the internal combustion engine is stopped.

  Further, according to this configuration, when the outside air temperature is high, that is, when the possibility of freezing and sticking of the blow-by gas rectifying valve is low, the opening degree of the blow-by gas rectifying valve is small when the internal combustion engine is stopped. Is set. As a result, it is possible to suppress the HC volatilized from the engine oil in the crankcase from entering the combustion chamber through the intake passage while the internal combustion engine is stopped, and to suppress the deterioration of the emission due to this. become.

  As a specific configuration of the blow-by gas recirculation device, for example, as described in claim 6, a throttle valve that adjusts an intake air amount is provided in the intake passage, and the blow-by gas recirculation device includes the intake passage. A portion located upstream of the throttle valve and the crankcase are connected to each other, an introduction passage for introducing the air in the intake passage into the crankcase, and a downstream side of the throttle valve in the intake passage. A breather passage that connects the portion located to the crankcase and circulates the blowby gas in the crankcase to the intake passage, and the blowby gas rectifying valve is provided in the breather passage. Can be adopted.

  According to a seventh aspect of the present invention, in the control device for an internal combustion engine according to the sixth aspect, the freeze fixation detecting means for detecting the freeze fixation of the throttle valve, and the freeze fixation detection means at the start of the internal combustion engine An intake air amount control means for controlling the intake air amount by changing the opening of the blow-by gas rectifying valve based on the engine operating state when freezing and sticking of the throttle valve is detected. The gist.

  When the outside air temperature is low, the throttle valve may be frozen and stuck while the internal combustion engine is stopped. If the throttle valve is frozen and fixed in this way, the intake air amount cannot be controlled by the throttle valve at the next engine start, and the startability of the engine may be deteriorated due to a shortage of the intake air amount.

  As described above, the blow-by gas recirculation device includes an introduction passage that connects a portion upstream of the throttle valve in the intake passage and the crankcase, and a portion downstream of the throttle valve in the intake passage and the crankcase. In the case where the breather passage to be connected is provided, when the opening degree of the blow-by gas rectifying valve changes, the total cross-sectional area of the passage through which the intake air flows changes, so that the intake air amount changes. Therefore, according to the above configuration, when the freezing and sticking of the throttle valve is detected at the start of the internal combustion engine, the amount of intake air is controlled by changing the opening of the blow-by gas rectifying valve. Even when freezing and sticking occurs, it is possible to suppress deterioration of the startability of the engine due to the inability to control the intake air amount.

  According to an eighth aspect of the present invention, in the control device for an internal combustion engine according to the sixth aspect, the internal combustion engine has a variable valve mechanism capable of changing an overlap amount during a valve opening period of the intake valve and the exhaust valve. An activation determining means for determining whether or not the exhaust purification catalyst is activated, and when the activation determination means determines that the exhaust purification catalyst is not activated when the internal combustion engine is started In addition, an early activation means for executing an early activation control for increasing the internal EGR amount by increasing the overlap amount through the variable valve mechanism and activating the exhaust purification catalyst at an early stage, and the early activation An annular flow rate restricting means for restricting the annular flow rate of the blowby gas by forcibly reducing the opening of the blowby gas rectifying valve during the execution of the early activation control by the activating means As its gist in that it comprises.

  As in the same configuration, when it is determined that the exhaust purification catalyst is not activated when the internal combustion engine is started, the internal EGR amount is reduced by increasing the overlap amount during the valve opening period of the intake valve and the exhaust valve. It can be increased to slow down the engine combustion rate. When the engine combustion speed becomes slow in this way, the exhaust gas temperature rises, so that the exhaust purification catalyst is activated early. By the way, when the overlap amount of the valve opening period of the intake valve and the exhaust valve is increased as described above, the negative pressure in the combustion chamber is reduced in the intake stroke, and the effect may be reduced when the engine brake is applied. .

  In this regard, in the above configuration, the flow rate of the blow-by gas is restricted by forcibly reducing the opening of the blow-by gas rectifying valve during the early activation control by the early activation means. Here, in the intake passage, the introduction passage connecting the portion located upstream of the throttle valve and the crankcase, and the breather passage connecting the crankcase and the portion located downstream of the throttle valve in the intake passage. When the blow-by gas recirculation device having the above is adopted, the opening amount of the blow-by gas rectifying valve is reduced, so that the total amount of gas sucked into the combustion chamber in the intake stroke is reduced and the negative pressure in the combustion chamber is increased. become. Therefore, according to the above configuration, when the early activation control is being performed, that is, when the overlap amount of the valve opening period of the intake valve and the exhaust valve becomes large, the opening degree of the blow-by gas rectifying valve is forcibly set. By making it small, the negative pressure in the combustion chamber can be secured, and the reduction in the engine braking effect can be suppressed.

  Further, when the blow-by gas is circulated through the intake passage during a period when the exhaust purification catalyst is not activated, NOx contained in the blow-by gas enters the exhaust system through the intake passage and the combustion chamber and is not reduced by the exhaust purification catalyst. There is a risk that emissions will deteriorate due to emissions. In this respect, according to the above configuration, by limiting the ring flow rate of the blow-by gas during the period when the exhaust purification catalyst is not activated, the deterioration of the emission due to the NOx contained in the blow-by gas being discharged to the atmosphere. It becomes possible to suppress.

  In addition, as described in claim 9, the ring flow rate restricting unit adopts a configuration in which the blow-by gas rectifying valve is fully closed during the execution of the early activation control by the early activation unit. It is desirable to do. By adopting such a configuration, it is possible to suppress the deterioration of the engine brake effect and the deterioration of the emission as much as possible.

(First embodiment)
A first embodiment in which the control device for an internal combustion engine according to the present invention is embodied as an electronic control device that comprehensively controls a vehicle-mounted internal combustion engine will be described below with reference to FIGS.

  FIG. 1 is a schematic configuration diagram schematically showing an internal combustion engine and an electronic control device thereof according to the present embodiment. As shown in FIG. 1, a plurality of cylinders 1 (only one of which is shown in the figure) are formed in a cylinder block of the internal combustion engine 100, and a piston 2 reciprocates in these cylinders 1. Each is accommodated as possible. The piston 2 is connected to the crankshaft 5 via the conroad 4, and the reciprocating motion of the piston 2 is converted into the rotational motion of the crankshaft 5 by the conroad 4 during engine operation. The conload 4 and the crankshaft 5 are accommodated in a crankcase 1 a located below the cylinder 1.

  A plurality of combustion chambers 3 are defined by the top surface of the piston 2 and the inner wall of the cylinder 1. Above these combustion chambers 3, an ignition plug 6 and an in-cylinder fuel injection valve 9 are provided, and an intake port 7 and an exhaust port 8 communicating with each combustion chamber 3 are formed. The intake port 7 is connected to the intake manifold 10 to constitute a part of the intake passage, and the exhaust port 8 is connected to the exhaust manifold 20 to constitute a part of the exhaust passage. The intake manifold 10 is provided with a throttle valve 12 for adjusting the amount of intake air, and the exhaust manifold 20 purifies hydrocarbons (HC) and nitrogen oxides (NOx) contained in the exhaust. An exhaust purification catalyst 22 is provided.

  In the upper part of the combustion chamber 3, there are provided an intake valve 11 for communicating / blocking the intake port 7 and the combustion chamber 3, and an exhaust valve 21 for communicating / blocking the exhaust port 8 and the combustion chamber 3. These intake / exhaust valves 11 and 21 are opened and closed by an intake camshaft and an exhaust camshaft connected to the crankshaft 5. The intake valve 11 and the exhaust valve 21 are respectively provided with variable valve mechanisms 30 and 40 that can change the valve opening timings of these valves.

  In addition, the internal combustion engine 100 according to the present embodiment is provided with a blow-by gas recirculation device 50 that recirculates gas that leaks from the combustion chamber 3 to the crankcase 1a in the combustion stroke, so-called blow-by gas, into the intake passage. The blow-by gas recirculation device 50 includes an introduction passage 51 that communicates a portion of the intake manifold 10 that is located upstream of the throttle valve 12 with the crankcase 1a, and a downstream side of the throttle valve 12 in the crankcase 1a and the intake manifold 10. The breather passage 52 communicates with the surge tank 13 located at the position, and the PCV valve 53 provided in the breather passage 52 for adjusting the ring flow rate of blow-by gas. With this configuration, when the PCV valve 53 is opened based on the engine operating state, a part of the intake air in the intake manifold 10 is introduced into the crankcase 1a through the introduction passage 51, and the blow-by gas in the crankcase 1a is It is introduced into the surge tank 13 through the breather passage 52. Note that the PCV valve 53 according to the present embodiment is an electronically controlled type in which the opening degree is adjusted based on an electrical signal regardless of the pressure difference between the crankshaft 5 and the intake manifold 10.

  The internal combustion engine 100 is provided with a plurality of sensors for detecting the engine operating state. For example, the intake manifold 10 is provided with an air flow meter 61 for detecting the amount of intake air and an opening sensor 62 for detecting the opening of the throttle valve 12. A crank sensor 63 is provided in the vicinity of the crankshaft 5 for detecting the rotational position of the crankshaft 5 and the engine rotational speed NE. An air-fuel ratio sensor 64 for detecting the rich / lean state of the air-fuel ratio of the air-fuel mixture is provided at a portion located upstream of the exhaust purification catalyst 22 in the exhaust manifold 20 and downstream of the exhaust purification catalyst 22. An oxygen sensor 65 for detecting the concentration of oxygen in the exhaust gas is provided in the portion located at. In addition, an accelerator opening sensor 66 for detecting the depression amount of the accelerator pedal, an ignition sensor 67 for detecting an on / off operation of an ignition switch (IG), an outside air temperature sensor 68 for detecting an outside air temperature, an engine A water temperature sensor 69 for detecting the coolant temperature, an intake pressure sensor 70 for detecting the pressure downstream of the throttle valve 12 of the intake manifold 10, that is, an intake pressure sensor, and an atmospheric pressure sensor for detecting the atmospheric pressure. 71 etc. are provided. The output signals of these sensors are taken in by an electronic control unit 60 that executes various controls of the internal combustion engine 100 in an integrated manner. The electronic control unit 60 includes a central processing unit that performs numerical calculation, information processing, and the like by a program, and a memory that stores programs and data necessary for various controls.

  As described above, an internal combustion engine including a conventional blowby gas recirculation device that employs a PCV valve that opens based on a pressure difference between the crankcase 1a and the intake passage as a rectifying valve for adjusting the amount of blowby gas. In this case, the following inconvenience may occur. That is, when a PCV valve that opens based on the pressure difference between the crankcase 1a and the intake passage is employed, for example, the pressure difference may be low during the operation period immediately before the engine stops, and the PCV valve may not be opened. Thus, when the PCV valve does not open during the operation period immediately before the engine stop, the blow-by gas generated during the operation period is stored in the crankcase 1a, and the engine oil in the crankcase 1a deteriorates when the engine stops. May occur. Further, when the blow-by gas is stored in the crankcase 1a when the engine is stopped as described above, the blow-by gas stored in the crankcase 1a is stored in the combustion chamber 3 when the engine is restarted after being in a cold state. It may be discharged into the exhaust system without burning. Here, the exhaust manifold 20 of the internal combustion engine is provided with an exhaust purification catalyst 22, but since the exhaust purification catalyst 22 is not activated in the cold state of the engine, the HC and NOx is exhausted to the atmosphere as it is, leading to a worsening of emissions.

  Therefore, in the present embodiment, the electronically controlled PCV valve 53 is employed as described above, and such inconvenience is caused by performing appropriate pre-stop control on the PCV valve 53 before the internal combustion engine 100 stops. I try to suppress it. Hereinafter, this control will be described with reference to the flowcharts of FIGS. The processes shown in FIGS. 2 and 3 are repeatedly executed by the electronic control device 60 with a predetermined period.

  In this process, first, it is determined whether or not an ignition turn-off command has been issued by the ignition sensor 67, in other words, whether or not the ignition switch has been turned off by the driver (step S10). When it is determined that there is no ignition-off command (step S10: NO), this process is temporarily terminated, while when it is determined that there is an ignition-off command (step S10: YES). Based on this command, the fuel cut (F / C) is executed (step S20).

  Then, after the fuel cut is performed in this way, it is determined whether or not the engine speed NE detected by the crank sensor 63 is equal to or higher than a predetermined speed NE0 (150 rpm in the present embodiment) set in advance (step). S30). Here, when it is determined that the engine speed NE is equal to or higher than the predetermined speed NE0 (step S30: YES), the PCV valve 53 is maintained in a fully opened state (step S40), and this process is temporarily terminated.

  On the other hand, when it is determined that the engine speed NE is lower than the predetermined speed NE0 (step S30: NO), the opening degree of the PCV valve 53 is controlled based on the outside air temperature (step S50). The flowchart of FIG. 3 shows a specific processing procedure of this control.

  That is, the outside air temperature Tg detected by the outside air temperature sensor 68 is read (step S51), and the target opening degree D of the PCV valve 53 when the engine is stopped is calculated with reference to the calculation map based on the outside air temperature Tg (step S51). S52). FIG. 4 shows the relationship between the outside air temperature Tg and the target opening degree D in this calculation map. As shown in FIG. 4, when the outside air temperature Tg is equal to or higher than the upper limit value TMX (0 ° C. in the present embodiment), the target opening degree D is set to be fully closed (0%), and the outside air temperature Tg is the lower limit. When the value TMN (−20 ° C. in this embodiment) or less is set, the target opening degree D is set to fully open (100%). When the outside air temperature Tg is between these upper and lower limits, the target opening degree D is set larger as the outside air temperature Tg is lower.

  Then, this is controlled so that the opening degree of the PCV valve 53 becomes the target opening degree D set in step S52 (step S53), and this series of processing is once ended. Thereby, the opening degree of the PCV valve 53 after the engine is stopped is maintained at the target opening degree D.

  Hereinafter, with reference to FIG. 5, a specific example of the above-described control before the engine stop will be described. FIG. 5 is a diagram showing temporal transitions of the ignition switch state, the fuel cut execution state, the engine speed NE, and the opening degree of the PCV valve 53 before and after the internal combustion stop.

  As shown in FIG. 5, when an ignition switch OFF operation is detected by the ignition sensor 67 at time T1, in other words, when there is an ignition off command (step S10: YES), a fuel cut is first executed (step S10: YES). Step S20). Immediately after the fuel cut is executed, the engine speed NE is equal to or higher than the predetermined speed NE0 (150 rpm) (step S30: YES), so the opening of the PCV valve 53 is fully opened (100%) from the expected opening. The PCV valve 53 is controlled to be fully opened (step S40).

  Then, when the engine speed NE gradually decreases and the engine speed NE becomes lower than the predetermined speed NE0 (150 rpm) at time T2 (step S30: NO), based on the outside air temperature Tg detected by the outside air temperature sensor 68. Thus, the target opening degree D is calculated (steps S51 and S52). For example, when it is determined that the outside air temperature Tg is equal to or higher than the upper limit value TMX (0 ° C.), the target opening degree D is set to fully closed (0%), and the opening degree of the PCV valve 53 is set to the target opening degree D. It is controlled to be (0%). As a result, the PCV valve 53 is kept fully closed after the engine is stopped (time T3).

When the control when the engine is stopped is completed and the internal combustion engine 100 is once cold, the engine may be restarted and the following inconvenience may occur.
That is, since the exhaust purification catalyst 22 is not activated in the cold state of the engine, HC and NOx contained in the exhaust gas may be exhausted as it is until the catalyst is activated. Therefore, in order to activate the exhaust purification catalyst 22 at an early stage, for example, an early activation control for increasing the internal EGR amount by increasing the overlap amount of the valve opening period of the intake valve 11 and the exhaust valve 21 is executed. Can do.

  Specifically, when it is determined that the exhaust purification catalyst 22 is not activated based on the concentration of oxygen in the exhaust gas detected by the oxygen sensor 65, the intake valve is passed through the variable valve mechanisms 30 and 40. The valve opening timings of these valves are changed so that the overlap amount of the valve opening period between the exhaust valve 11 and the exhaust valve 21 increases. As a result, the internal EGR amount increases, the combustion speed of the engine becomes slow, and the exhaust temperature rises. As a result, the exhaust purification catalyst 22 is activated early. By the way, when the overlap amount of the valve opening period of the intake valve 11 and the exhaust valve 21 is increased as described above, the negative pressure in the combustion chamber 3 is decreased in the intake stroke, and the effect is reduced when the engine brake is applied. There is a fear.

  Further, when the blow-by gas is circulated to the intake manifold 10 during a period when the exhaust purification catalyst 22 is not activated when the engine is started, NOx contained in the blow-by gas enters the exhaust passage through the intake passage and the combustion chamber 3 to purify the exhaust. There is a possibility that emissions are deteriorated by being discharged to the atmosphere without being reduced by the catalyst 22.

Therefore, in this embodiment, such inconvenience is suppressed by executing the start time control described below when the internal combustion engine 100 is started.
Hereinafter, the starting control will be described with reference to the flowchart of FIG. The processing shown in FIG. 6 is repeatedly executed by the electronic control device 60 with a predetermined period after the ignition switch is turned on.

  In this process, it is first determined whether or not the internal combustion engine 100 has completely exploded based on the engine speed NE or the like (step S110). When it is determined that the internal combustion engine 100 is not completely detonated (step S110: NO), the HC generated in the crankcase 1a when the engine is stopped is prevented from being exhausted without being completely combusted in the combustion chamber 3. Therefore, the PCV valve 53 is controlled to be fully closed (step S120), and this series of processes is temporarily terminated. On the other hand, when it is determined that the internal combustion engine 100 has completely exploded (step S110: YES), it is determined whether or not the above-described early activation control is being executed (step S130).

  If it is determined that the early activation control is being executed (step S130: YES), the PCV valve 53 is controlled to be fully closed (step S140). On the other hand, when it is determined that the early activation control is not being executed (step S130: NO), the water temperature Tw of the engine cooling water detected by the water temperature sensor 69 is a predetermined determination temperature (in this embodiment). 0 ° C.) or less (step S150).

  When it is determined that the water temperature Tw is equal to or lower than the determination temperature (step S150: YES), it is determined that there is a high possibility that the PCV valve 53 is frozen and fixed, and the calculation shown in FIG. The opening degree of the PCV valve 53 is set with reference to the map (step S160). When it is determined that the water temperature Tw is higher than the determination temperature (step S150: NO), it is determined that there is a low possibility that the PCV valve 53 is frozen and fixed, and normal control of the PCV valve 53, that is, presetting is performed. The control for setting the opening degree of the PCV valve 53 based on the engine operating state is executed with reference to the normal operation control map thus obtained (step S170).

  Next, a specific example of the above starting control will be described with reference to FIG. FIG. 7 is a diagram showing temporal transitions of the ignition switch state, the engine speed NE, the early activation control execution state, and the opening degree of the PCV valve 53 before and after the engine start.

  As shown in FIG. 7, when the ignition switch is turned on at time t1, since the engine has not completely exploded (step S110: NO), the PCV valve 53 is controlled to be fully closed (step S120). ). When it is determined that the engine has completely exploded at time t2 (step S110: YES), early activation control is executed (step S130: YES), and the PCV valve 53 is continuously controlled to the fully closed state. (Step S140).

  After the early activation control is completed at time t3 (step S130: NO), when it is determined that the water temperature Tw is higher than the determination temperature (0 ° C.) (step S150: NO), the normal control of the PCV valve 53 is performed. This is executed (step S170).

According to the first embodiment described above, the following effects can be obtained.
(1) An electrically driven PCV valve 53 is employed as a rectifying valve for adjusting the ring flow rate of blow-by gas. As a result, the flow rate of the blow-by gas can be freely adjusted without depending on the pressure difference, for example, as compared with the case where a rectifying valve that opens based on the pressure difference between the crankcase 1a and the intake manifold 10 is adopted. Will be able to. Further, the PCV valve 53 is maintained in a fully opened state when a fuel cut is executed based on a command to stop the internal combustion engine 100. Thereby, before the internal combustion engine 100 stops, discharge | emission of blowby gas in the crankcase 1a can be accelerated as much as possible, and it is suppressed that blowby gas is stored in the crankcase 1a when the internal combustion engine 100 stops. Can do. Here, since the exhaust purification catalyst 22 is activated after the fuel cut is executed until the internal combustion engine 100 is stopped, HC and NOx contained in the blow-by gas can be purified, and the same component can be obtained. Exhaust into the atmosphere can be suppressed. Therefore, according to the configuration of this embodiment, it is possible to suppress deterioration of engine oil and emission due to the blow-by gas being stored in the crankcase 1a when the engine is stopped.

  (2) The PCV valve 53 is maintained in the fully opened condition on condition that the engine speed NE is equal to or higher than the predetermined speed NE0. Here, when the opening degree of the PCV valve 53 is constant, the lower the engine speed NE, the smaller the flow rate of the blow-by gas, and the effect of discharging the blow-by gas in the crankcase 1a by the blow-by gas recirculation device 50. Will fall. Therefore, since the control for discharging the blow-by gas is executed only when the engine speed NE is high, that is, when the efficiency of discharging the blow-by gas in the crankcase 1a is high, the control is simplified. Will be able to.

  (3) The opening degree of the PCV valve 53 when the engine is stopped is increased as the outside air temperature Tg is lower when the internal combustion engine 100 is stopped. Here, when the outside air temperature is low, the PCV valve 53 may be frozen and fixed after the internal combustion engine 100 is stopped. The smaller the opening of the PCV valve 53, that is, the valve body and the valve seat of the PCV valve 53. The closer the distance to is, the more likely the freezing and sticking of the rectifying valve occurs. Therefore, by setting the opening degree of the PCV valve 53 at the time of engine stop based on the outside air temperature Tg as described above, even if the outside air temperature Tg is low, after the internal combustion engine 100 is stopped, the PCV valve 53 It is possible to suitably suppress the occurrence of freezing and sticking.

  Further, according to this configuration, when the outside air temperature Tg is high, that is, when the possibility of freezing and sticking of the PCV valve 53 is low, the opening degree of the PCV valve 53 while the engine is stopped is set small. As a result, it is possible to suppress the HC volatilized from the engine oil in the crankcase 1a from entering the combustion chamber 3 through the intake passage while the engine is stopped, and to suppress the deterioration of the emission caused by this. become.

(4) The PCV valve 53 is controlled to be fully closed during execution of the early activation control when the engine is started. In this way, when the PCV valve 53 is fully closed to restrict the flow rate of the blow-by gas, when the overlap amount of the intake valve 11 and the exhaust valve 21 in the early activation control becomes large, The negative pressure of the combustion chamber 3 can be ensured, and the reduction of the engine braking effect can be suppressed. In addition, by limiting the ring flow rate of the blowby gas during the period when the exhaust purification catalyst 22 is not activated in this way, it is possible to suppress the deterioration of the emission due to the NOx contained in the blowby gas being discharged to the atmosphere. Will be able to.
(Second Embodiment)
Hereinafter, the second embodiment according to the present invention will be described focusing on differences from the first embodiment. Also in the second embodiment, the basic configuration of the internal combustion engine 100 and the electronic control unit 60 is the same as that of the first embodiment, and only the control at the time of starting the engine is different from the first embodiment. Yes.

  When the outside air temperature Tg is low, the throttle valve 12 may be frozen and fixed while the engine is stopped. If the throttle valve 12 is frozen and fixed in this way, the intake air amount cannot be controlled by the throttle valve 12 at the next engine start, and the startability of the engine may be deteriorated due to the shortage of the intake air amount.

  Therefore, in the second embodiment, such an inconvenience is suppressed by executing the following intake air amount control when the engine is started. FIG. 8 shows a processing procedure for the intake air amount control. The processing shown in FIG. 8 is repeatedly executed with a predetermined cycle by the electronic control unit 60 after the internal combustion engine 100 is started.

  Based on the output of the opening sensor 62 described above, it is determined whether the throttle valve 12 has been frozen and stuck (step S210). If it is determined that freezing and sticking of the throttle valve 12 has not occurred (step S210: NO), this process is temporarily terminated. On the other hand, when it is determined that the throttle valve 12 is frozen and stuck, the control target value of the opening degree of the throttle valve 12 is prevented in order to prevent a sudden change in the intake air amount due to the elimination of the frozen and stuck throttle valve 12. Is set to the opening at that time, in other words, the drive control of the throttle valve 12 is stopped (step S220).

  Then, a deviation between the actual value of the engine speed NE detected by the crank sensor 63 and its control target value is calculated (step S230), and an insufficient amount of intake air is calculated based on this deviation (step S240). .

  Next, based on the shortage of the intake air amount and the pressure difference ΔP before and after the throttle valve 12, the opening of the PCV valve 53 is controlled with reference to the calculation map (step S250), and this series of control is temporarily performed. finish. The pressure difference before and after the throttle valve 12 can be detected based on the outputs of the intake pressure sensor 70 and the atmospheric pressure sensor 71 described above. FIG. 9 shows the relationship between the shortage of the intake air amount and the pressure difference ΔP and the opening degree of the PCV valve 53 in the calculation map. As shown in FIG. 9, the opening degree of the PCV valve 53 is set larger as the deficient amount of the intake air amount is larger or the pressure difference ΔP is smaller.

According to the second embodiment described above, the following effects can be obtained in addition to the effects (1) to (3) of the first embodiment.
(5) When it is determined that the exhaust purification catalyst 22 is activated and the freezing and sticking of the throttle valve 12 is detected, the amount of intake air is controlled by changing the opening of the PCV valve 53. did. Here, when the outside air temperature Tg is low, the throttle valve 12 may be frozen and fixed while the engine is stopped. Even if the early activation control of the exhaust purification catalyst 22 is completed, if the freezing and sticking of the throttle valve 12 is not eliminated, the intake air amount cannot be controlled by the throttle valve 12 when starting the engine, and the intake air amount is insufficient. As a result, the startability of the engine may be deteriorated. Therefore, by controlling the intake air amount by changing the opening degree of the PCV valve 53 as described above, it is possible to suppress deterioration of the startability of the engine due to the inability to control the intake air amount. .

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
In the first embodiment, the PCV valve 53 is fully closed during the early activation control of the exhaust purification catalyst 22 at the time of engine startup. For example, a configuration in which the opening degree of the PCV valve 53 is reduced to an opening degree other than the fully closed position may be employed. By adopting such a configuration, it is possible to limit the flow rate of the blow-by gas during the early activation control.

  Further, for example, during execution of the above-described early activation control, the influence on the engine braking effect due to the valve opening overlap between the intake valve 11 and the exhaust valve 21 can be ignored, and the ring flow rate of blow-by gas is limited. When it is not necessary, normal control of the PCV valve 53 may be executed without controlling the opening degree of the PCV valve 53 small.

  In the first embodiment, after the early activation control is completed at the time of starting the engine, when the water temperature Tw is equal to or lower than the determination temperature, it is shown in FIG. 4 in order to suppress freezing and sticking of the PCV valve 53. The opening degree of the PCV valve 53 is set with reference to the calculation map. For example, even if the PCV valve 53 is once frozen, if the freezing can be quickly eliminated by the heat generated by the engine, the control for suppressing the freeze-fixing of the PCV valve 53 described above may be omitted.

  In each of the above embodiments, the opening degree of the PCV valve 53 when the engine is stopped is set to be larger as the outside air temperature Tg is lower with reference to the calculation map shown in FIG. Not limited to this, a configuration is adopted in which the opening degree of the PCV valve 53 when the engine is stopped is set by reducing the opening degree of the PCV valve 53, which is once fully controlled, by a predetermined amount without referring to the above calculation map. You can also Further, for example, even if the PCV valve 53 is frozen when the engine is stopped, if the freezing can be quickly eliminated by the heat generation of the engine after the engine is started, the control on the opening degree of the PCV valve 53 when the engine is stopped is performed. You may omit it.

  In each of the above embodiments, after the ignition switch is turned off, the PCV valve 53 is fully opened on condition that the engine speed NE is equal to or higher than the predetermined speed NE0. However, the engine speed NE is “ It is also possible to adopt a configuration in which the PCV valve 53 is fully opened before reaching “0 rpm”. Further, it is not always necessary to fully open the PCV valve 53, and if the PCV valve 53 is kept open at a predetermined opening, it is possible to ensure that blow-by gas is discharged before the engine is stopped.

1 is a schematic configuration diagram schematically showing an internal combustion engine and an electronic control device thereof according to a first embodiment of the present invention. The flowchart which shows the process sequence about the control before the engine stop performed by the electronic controller which concerns on the same embodiment. The flowchart which shows the process sequence about the control before the engine stop performed by the electronic controller which concerns on the same embodiment. The figure which shows the relationship between the external temperature in the calculation map used for the said control before a stop, and the target opening degree of a PCV valve. The figure which shows the time transition of the state of an ignition switch, the implementation state of a fuel cut, an engine speed, and the opening degree of a PCV valve before and after engine stop when the pre-stop control is executed. The flowchart which shows the process sequence about the control at the time of the engine starting performed by the electronic controller which concerns on the same embodiment. The figure which shows the time transition of the state of an ignition switch, the engine speed, the execution state of early activation control, and the opening degree of a PCV valve before and after engine start when the above-mentioned start time control is executed. The flowchart which shows the process sequence about the control at the time of the engine starting performed by the electronic controller which concerns on the 2nd Embodiment of this invention. The figure which shows the relationship between the shortage of the amount of intake air, a pressure difference, and the opening degree of a PCV valve in the calculation map used for the said starting control.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Cylinder, 1a ... Crankcase, 2 ... Piston, 3 ... Combustion chamber, 4 ... Comload, 5 ... Crankshaft, 6 ... Spark plug, 7 ... Intake port, 8 ... Exhaust port, 9 ... In-cylinder fuel injection valve, DESCRIPTION OF SYMBOLS 10 ... Intake manifold, 11 ... Intake valve, 12 ... Throttle valve, 13 ... Surge tank, 20 ... Exhaust manifold, 21 ... Exhaust valve, 22 ... Exhaust purification catalyst, 30 ... Variable valve mechanism, 40 ... Variable valve mechanism, DESCRIPTION OF SYMBOLS 50 ... Blow-by gas recirculation apparatus, 51 ... Introduction passage, 52 ... Breather passage, 53 ... PCV valve, 60 ... Electronic control device (opening maintenance means, stop-time opening setting means, outside air temperature detection means, freezing and sticking detection means, Intake air amount control means, activation determination means, early activation means, circulation flow rate limiting means), 61 ... air flow meter, 62 ... opening sensor, 63 ... crank sensor, 64 Air-fuel ratio sensor, 65 ... oxygen sensor, 66 ... accelerator opening sensor, 67 ... ignition sensor, 68 ... outside air temperature sensor, 69 ... water temperature sensor, 70 ... intake pressure sensor, 71 ... atmospheric pressure sensor, 100 ... internal combustion engine.

Claims (9)

In a control device for an internal combustion engine comprising a blow-by gas recirculation device for recirculating blow-by gas in a crankcase to an intake passage, and an exhaust purification catalyst provided in an exhaust system for purifying exhaust gas,
The blow-by gas recirculation device is provided with an electronically controlled blow-by gas rectifying valve for adjusting the flow rate of the blow-by gas, and when the fuel cut is executed based on a command to stop the internal combustion engine, A control device for an internal combustion engine, comprising: opening degree maintaining means for maintaining the gas rectifying valve in an open state. The control apparatus for an internal combustion engine according to claim 1,
The control device for an internal combustion engine, wherein the opening degree maintaining means maintains the blow-by gas rectifying valve in a fully opened state when a fuel cut is executed based on a command to stop the internal combustion engine. The control apparatus for an internal combustion engine according to claim 1 or 2,
The control device for an internal combustion engine, wherein the opening degree maintaining means maintains the blow-by gas rectifying valve in an open state on condition that the rotational speed of the internal combustion engine is equal to or higher than a predetermined speed. The control apparatus for an internal combustion engine according to any one of claims 1 to 3,
After the control of the blow-by gas rectifying valve by the opening maintaining means is completed, the blow-by gas adjustment when the internal combustion engine is stopped to a value smaller than the opening of the blow-by gas rectifying valve set in the control. A control device for an internal combustion engine, comprising: a stop-time opening setting means for setting the opening of the flow valve. The control apparatus for an internal combustion engine according to any one of claims 1 to 3,
After the control of the outside air temperature detecting means for detecting the outside air temperature and the blow-by gas rectifying valve by the opening degree maintaining means is completed, the lower the outside air temperature detected by the outside air temperature detecting means, the lower the temperature of the internal combustion engine. A control device for an internal combustion engine, comprising: a stop-time opening setting means for setting a large opening of the blow-by gas rectifying valve when stopped. In the control device for an internal combustion engine according to any one of claims 1 to 5,
The intake passage is provided with a throttle valve for adjusting the amount of intake air, and the blow-by gas recirculation device connects a portion of the intake passage that is located upstream of the throttle valve and the crankcase. An inlet passage for introducing air in the passage into the crankcase, a portion located downstream of the throttle valve in the intake passage and the crankcase are connected, and the blow-by gas in the crankcase is sucked into the intake air A control device for an internal combustion engine, comprising: a breather passage for circulating in the passage, wherein the blow-by gas rectifying valve is provided in the breather passage. The control apparatus for an internal combustion engine according to claim 6,
Freezing and sticking detecting means for detecting freezing and sticking of the throttle valve; and when the freezing and sticking detecting means is detected by the freezing and sticking detecting means when the internal combustion engine is started, the blow-by gas adjustment is performed based on the engine operating state. An internal combustion engine control device comprising: an intake air amount control means for controlling the intake air amount by changing an opening of a flow valve. The control apparatus for an internal combustion engine according to claim 6,
The internal combustion engine is provided with a variable valve mechanism capable of changing an overlap amount during the valve opening period of the intake valve and the exhaust valve, and an activation determination means for determining whether or not the exhaust purification catalyst has been activated. When the internal combustion engine is started, when the activation determination means determines that the exhaust purification catalyst is not activated, the internal EGR amount is increased by increasing the overlap amount through the variable valve mechanism. Early activation means for performing early activation control for activating the exhaust purification catalyst early, and opening degree of the blow-by gas rectifying valve during execution of the early activation control by the early activation means. An internal combustion engine control device comprising: an annular flow rate restricting means for restricting an annular flow rate of the blow-by gas by forcibly reducing the flow rate. The control apparatus for an internal combustion engine according to claim 8,
The control apparatus for an internal combustion engine, wherein the ring flow restriction means fully closes the blow-by gas rectifying valve during execution of the early activation control by the early activation means.

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