JP4383983B2 - Blowby gas recirculation system - Google Patents

Description

  The present invention relates to a blow-by gas recirculation apparatus.

  Diesel engine exhaust gas contains particulate matter (particulates) mainly composed of carbon, which causes black smoke. For this reason, in order to collect particulate matter on the exhaust passage of many internal combustion engines, a porous heat-resistant filter (particulate filter) with good air permeability is provided, and this filter purifies the exhaust gas. Has been done.

  If the exhaust gas is continuously collected by such a filter, particulate matter accumulates on the filter and the air permeability of the filter is lost, and the pressure loss due to the filter increases. Therefore, in order to suppress an excessive increase in pressure loss, it is necessary to periodically remove the accumulated particulate matter. As a means for removing the accumulated particulate matter, for example, the temperature of the filter is raised to the combustion temperature of the particulate matter. This is because the particulate matter is burned by oxygen in the exhaust gas.

  Various means for raising the temperature of the filter have been proposed, and one of them is the method disclosed in Patent Document 1. That is, additional injection of fuel is performed after the main injection separately from the main injection performed near the compression top dead center from the fuel injection valve that directly injects fuel into the combustion chamber. The additionally injected fuel is combusted in the combustion chamber to raise the temperature of the exhaust gas, and as a result, the temperature of the filter is raised. Alternatively, the additionally injected fuel reaches the filter without being burned in the combustion chamber and is contained in the exhaust gas, and is oxidized in the filter. Then, the temperature of the filter is raised by reaction heat in the oxidation reaction.

JP 07-259533 A Japanese Patent Publication No. 03-040210 Japanese Utility Model Publication No. 05-087213 Japanese Patent Laid-Open No. 06-108818 JP-A-06-212939

  By the way, when additional injection is performed, a part of the injected fuel may reach the cylinder wall surface that defines the combustion chamber without being vaporized, and may adhere to the cylinder wall surface. The fuel adhering to the cylinder wall in this way is scraped off into the crankcase by the reciprocating piston and mixed into the lubricating oil stored in the crankcase.

  When fuel is mixed in the lubricating oil, the lubricating oil is diluted, leading to deterioration of the properties of the lubricating oil and deterioration of the lubricating performance of the lubricating oil. In particular, the viscosity of the lubricating oil is easily lost due to fuel mixing, resulting in a problem that bearing seizure occurs.

  Therefore, an object of the present invention is to suppress deterioration of the properties of the lubricating oil due to the fuel being mixed into the lubricating oil.

In order to solve the above problems, in the first invention, the supercharger and an intercooler that cools the intake gas pressurized by the supercharger are used in an internal combustion engine provided on an intake passage. Blow-by gas comprising an air introduction passage for allowing intake gas in the intake passage to flow into the crankcase of the internal combustion engine, and a gas recirculation passage for returning blow-by gas in the crankcase of the internal combustion engine into the intake passage. In the recirculation device, the air introduction passage communicates with the intake passage downstream of the supercharger and upstream of the intercooler.
According to the first invention, since the air introduction passage communicates with the intake passage downstream of the turbocharger and upstream of the intake air of the intercooler, the high-temperature intake gas passes through the air introduction passage in the crankcase. To be introduced. Since the introduced intake gas has a high temperature, the fuel is easily vaporized from the lubricating oil when the fuel is mixed in the lubricating oil.

According to a second invention, in the first invention, the air introduction passage is provided with a flow rate control valve for controlling a flow rate of the intake gas flowing in the air introduction passage, and the gas recirculation passage is provided in the intake air of the supercharger. It communicates with the intake passage on the upstream side.
According to the second aspect of the invention, the air introduction passage through which the intake gas is introduced from the intake passage into the crankcase flows higher pressure intake gas than the gas recirculation passage through which the blowby gas is recirculated from the crankcase to the intake passage. Since it is connected to the intake passage, intake gas can be effectively introduced into the crankcase. In addition, since the flow control valve is provided in the air introduction passage, an intake gas necessary for vaporizing the fuel from the lubricating oil can be introduced into the crankcase.

According to a third aspect, in the second aspect, the internal combustion engine is capable of post-injection in which fuel injection is performed at a timing later than normal main injection, and the flow rate control valve is configured to perform the flow rate after the start of the post-injection. The control valve is opened, and the flow rate control valve is closed after a predetermined period has elapsed since the end of the post injection.
When the intake gas is introduced into the crankcase, the lubricating oil is slightly vaporized in addition to the fuel mixed in the lubricating oil. According to the third aspect of the invention, the flow rate control valve is basically opened only during the execution period of the post-injection, that is, the intake gas is introduced into the crankcase only during the period. Minimized.
Note that “post-injection” means main injection executed at a timing later than normal main injection, and injection executed separately from the main injection at a timing later than main injection. The “predetermined period” is a period necessary for evaporating the fuel still mixed in the lubricating oil when the flow control valve is closed, for example.

  According to the present invention, since the intake gas introduced into the crankcase is hot, the fuel is easily vaporized from the lubricating oil when the fuel is mixed in the lubricating oil, and thus the fuel is mixed into the lubricating oil. As a result, deterioration of the properties of the lubricating oil is suppressed.

  The present invention will be described below with reference to the drawings. FIG. 1 shows a diesel-type compression ignition type internal combustion engine in which the present invention is used. The present invention is also applicable to a spark ignition type internal combustion engine.

  Referring to FIG. 1, 1 is an engine body, 2 is a cylinder block, 3 is a cylinder head, 4 is a cylinder head cover, and 5 is an oil pan. In each cylinder of the cylinder block 2, the piston 6 reciprocates, whereby the volume of the combustion chamber 7 defined by the cylinder block 2, the cylinder head 3 and the piston 6 is varied. The cylinder block 2 is provided with a crankcase 8 that communicates with each cylinder and in which a crankshaft is disposed. The cylinder head 3 is provided with an electronically controlled fuel injection valve 9 for injecting fuel into the combustion chamber 7, an intake port 10 for allowing intake gas to flow into the combustion chamber 7, and the combustion chamber 7. An exhaust port 11 for exhausting exhaust gas is provided. The intake port 10 and the exhaust port 11 are opened and closed by an intake valve (not shown) and an exhaust valve (not shown), respectively.

  Lubricating oil for lubricating each operation mechanism of the engine body 1 is stored in the oil pan 5. Lubricating oil is sent to each operating mechanism of the engine body by an oil pump (not shown). For example, lubricating oil is provided on the cylinder wall surface to reduce the frictional resistance between the piston 6 and the cylinder, or in the valve mechanism chamber 12 in the cylinder head cover 4 so as to open and close the intake valve and the exhaust valve. In order to reduce the frictional resistance in the arranged valve mechanism (not shown), it is provided to the valve mechanism or the like. Lubricating oil provided to each operating mechanism arranged in the cylinder head cover 4 such as a valve operating mechanism is returned to the oil pan 5 through the oil return passage 13.

  The intake port 10 is connected to a surge tank 21 via a corresponding intake branch pipe 20, and the surge tank 21 is connected to a compressor 24 of a supercharger (exhaust turbocharger) 23 via an intake duct 22. The compressor 24 is connected to an air cleaner 26 via an intake duct 25. A throttle valve 28 driven by a step motor 27 and a cooling device (intercooler) 29 for cooling the intake gas flowing in the intake duct 22 are disposed in the intake duct 22. In the internal combustion engine shown in FIG. 1, engine cooling water is guided into the intercooler 29, and the intake gas is cooled by the engine cooling water. In FIG. 1, the arrows shown in the intake passage (the passage defined by the intake ducts 25 and 22, the surge tank 21, the intake branch pipe 20, the intake port 10 and the like) indicate the flow of the intake gas.

  On the other hand, the exhaust port 11 is connected to an exhaust turbine 37 of the exhaust turbocharger 23 via an exhaust branch pipe 35 and an exhaust pipe 36. The outlet of the exhaust turbine 37 is connected to a casing 40 containing a particulate filter (hereinafter referred to as “filter”) 39 via an exhaust pipe 38. In FIG. 1, the arrows shown in the exhaust passage (the passage defined by the exhaust port 11, the exhaust branch pipe 35, the exhaust pipes 36, 38, etc.) indicate the flow of the exhaust gas.

  Each fuel injection valve 9 is connected to a fuel reservoir, a so-called common rail (not shown) via a fuel supply pipe. Fuel is supplied into the common rail from an electrically controlled fuel pump with variable discharge amount, and the fuel supplied into the common rail is supplied to the fuel injection valve 9 via each fuel supply pipe. A fuel pressure sensor for detecting the fuel pressure in the common rail is attached to the common rail, and the discharge amount of the fuel pump is controlled based on the output signal of the fuel pressure sensor so that the fuel pressure in the common rail becomes the target fuel pressure. The

  The electronic control unit (ECU) 50 is a digital computer and includes a ROM, a RAM, a CPU, an input port, and an output port connected to each other by a bidirectional bus. The intake duct 25 is provided with a flow rate sensor 51 for detecting the flow rate of intake gas passing through the intake duct 25. Further, a temperature sensor 52 for detecting the exhaust temperature and estimating the temperature of the filter 40 is provided downstream of the filter 40, and the exhaust upstream and exhaust of the filter 40 are disposed upstream and downstream of the filter 40. A differential pressure sensor 53 is provided for detecting a differential pressure of the exhaust gas with respect to the downstream (hereinafter referred to as “front-rear differential pressure”). The output signals of these sensors are input to the input port of the ECU through corresponding AD converters. On the other hand, the output port of the ECU 50 is connected to the fuel injection valve 9, the step motor 27, the fuel pump, and the like via a corresponding drive circuit.

  By the way, a part of the air-fuel mixture in the combustion chamber 7 passes through the gap between the piston 6 and the cylinder wall surface and the gap between the intake valve and the outer periphery of the exhaust valve. Leaked inside. The gas containing the fuel leaking into the crankcase 8 or the like in this way is called blow-by gas, and it is called unburned gas (gas containing unburned hydrocarbon (HC) or partially oxidized fuel) and exhaust gas. It consists of. Therefore, since blow-by gas contains HC, if it is opened to the atmosphere as it is, it causes air pollution. Further, blow-by gas contains a small amount of water, and this water shows strong acidity, so that the inside of the internal combustion engine is polluted and the lubricating oil is deteriorated. Therefore, it is necessary to discharge the blow-by gas from the crankcase 8 or the like without releasing it to the atmosphere.

  For this reason, in many internal combustion engines, conventionally, a mechanism has been employed in which blow-by gas in the crankcase 8 or the like is recirculated to the intake passage and reflowed into the combustion chamber 7 for combustion treatment. In the present embodiment, two gas recirculation passages 61 and 62 for recirculating blowby gas from the crankcase 8 or the like to the intake passage, and intake gas (fresh air gas, intake air) are introduced into the crankcase 8 or the like. An air introduction passage 63 is provided.

  One of the two gas recirculation passages (hereinafter referred to as “first gas recirculation passage”) 61 communicates the crankcase 8 with the intake duct 25 on the intake upstream side of the compressor 24 of the exhaust turbocharger 23. The other of the two gas recirculation passages (hereinafter referred to as “second gas recirculation passage”) 62 communicates the valve mechanism chamber 12 with the intake duct 25 on the intake upstream side of the compressor 24. Blow-by gas is also allowed to flow into the valve mechanism chamber 12 from the crankcase 8 via the oil return passage 13, but the second gas recirculation passage 62 also guides the blow-by gas in the valve mechanism chamber 12 to the intake passage. It is burned. By these gas recirculation passages 61 and 62, the blow-by gas in the crankcase 8 and the valve mechanism chamber 12 is recirculated to the intake passage without being released to the atmosphere, and flows into the combustion chamber 7 again.

  In the present embodiment, an air introduction passage 63 that connects the crankcase 8 and the intake passage is provided. According to the air introduction passage 63, intake gas is introduced into the crankcase 8. As described above, the intake gas is introduced into the crankcase 8 and the valve mechanism chamber 12, whereby the blowby gas is sequentially discharged from the crankcase 8 and the like through the blowby gas passages 61 and 62. Accordingly, it is possible to prevent the blow-by gas from staying in the crankcase 8 and the like, thereby suppressing the internal pollution of the internal combustion engine by the blow-by gas and the deterioration of the lubricating oil. The air introduction passage 63 is provided with a flow rate control valve 64 for adjusting the flow rate of the intake gas flowing into the crankcase 8 and the like through the air introduction passage 63. The flow control valve 64 is connected to the output port of the ECU 50 via a corresponding drive circuit.

  By the way, the particulate filter 39 collects particulate matter (Particulate Matter) in the exhaust gas discharged from the combustion chamber 7, but the collected particulate matter accumulates on the surface of the filter 39 and the like. When the accumulation amount increases, the filter 39 is clogged. Such clogging causes an increase in the pressure loss of the exhaust gas due to the filter 39, which in turn leads to a deterioration in the operating state of the internal combustion engine. For this reason, in many internal combustion engines including the filter 39, the temperature of the filter 39 is controlled to increase the temperature of the filter 39 to the combustion temperature of the particulate matter, thereby oxidizing and removing the particulate matter. Like to do.

  Specifically, the differential pressure sensor 53 detects the differential pressure across the filter 39. The differential pressure across the filter 39 changes according to the amount of particulate matter deposited on the filter 39, and the differential pressure across the filter 39 increases as the amount of particulate matter deposited increases. Therefore, when the differential pressure across the filter 39 becomes equal to or higher than a predetermined value, that is, when the accumulation amount of the particulate matter becomes equal to or higher than the predetermined accumulation amount, the temperature increase control is executed. In the temperature rise control, the temperature of the filter 39 is raised until the temperature of the filter 39 detected by the temperature sensor 52 becomes equal to or higher than the combustion temperature of the particulate matter, and the accumulated particulate matter remains after the temperature rise. The temperature of the filter 39 is maintained at that temperature until it is completely removed.

  In the present embodiment, the temperature rise control of the filter 39 is performed by controlling the fuel injection pattern as described below. That is, FIG. 2 is a schematic diagram showing four examples of fuel injection patterns that can be implemented in the internal combustion engine shown in FIG. 1, but during normal operation of the internal combustion engine (operation without temperature increase control). 2), the injection pattern shown in (I) of FIG. 2 is set according to the engine operating state. That is, in the injection pattern shown in FIG. 2 (I), only the main injection Qm is performed near the compression top dead center, or the pilot injection Qpi is performed immediately before the main injection Qm near the compression top dead center. Is called. On the other hand, when the temperature of the filter 39 needs to be raised, the fuel injection pattern as shown in (II) to (IV) of FIG. 2 is obtained.

  In the fuel injection pattern shown in FIG. 2 (II), the after injection Qa is performed at the beginning of the expansion stroke after the main injection Qm. Here, the injection timing of the after injection Qa is immediately after the end of the main injection or after a relatively short interval from the end of the main injection (for example, within 60 ° CA after the end of the main injection). With such a fuel injection pattern, since the injection timing of the after injection is early, most of the fuel injected by the after injection burns in the combustion chamber 7, so that at the time when it is discharged from the combustion chamber 7 The temperature of the exhaust gas can be raised. And the temperature of the filter 39 can be raised by raising the exhaust gas temperature in this way.

  In the injection pattern shown in FIG. 2 (III), in addition to the main injection Qm and after injection Qa, or in addition to the main injection Qm, post injection Qpo is performed after these injections. Here, the injection timing of the post injection Qpo is after a relatively long interval from the end of the main injection (for example, 100 ° CA or more (preferably ATDC 110 to 130 ° CA) after the end of the main injection). In such a fuel injection pattern, since the injection timing of the post injection is late, most of the fuel injected by the post injection is discharged from the combustion chamber 7 without being burned in the combustion chamber 7. For this reason, the exhaust gas containing unburned fuel flows into the filter 39. When a noble metal such as platinum is supported on the filter 39, unburned fuel in the exhaust gas is oxidized in the filter 39, and the temperature of the filter 39 can be raised by the reaction heat.

  In the fuel injection pattern shown in FIG. 2 (IV), the injection timing of the main injection Qm is retarded until after the compression top dead center. Even when such a fuel injection pattern is used, the temperature of the filter 39 can be increased for the same reason as in the case of after-injection as shown in FIG.

  In the following description, as shown in the fuel injection patterns shown in (II) to (IV) of FIG. 2, the timing is later than the injection timing of the main injection in the normal operation shown in (I) of FIG. The injection performed is referred to as “post injection”. Therefore, “post-injection” includes post-injection and post-injection as well as retarded main injection.

  By the way, when performing post-injection, a part of the post-injected fuel may reach the cylinder wall without being vaporized in the combustion chamber 7, and may adhere to the cylinder wall (bore flushing). A part of the fuel that has reached the cylinder wall surface is scraped into the crankcase 8 by the reciprocating motion of the piston 6 and mixed into the lubricating oil stored in the oil pan 5. As described above, when fuel is mixed in the lubricating oil, the lubricating oil is diluted, leading to deterioration of the properties of the lubricating oil, particularly a decrease in the viscosity of the lubricating oil. If such a decrease in the viscosity of the lubricating oil is left unattended, bearing seizure occurs on the crankshaft, camshaft, and the like. Therefore, it is necessary to remove the fuel mixed in the lubricating oil from the lubricating oil, particularly during the execution of the post-injection.

  Here, since the boiling point of fuel such as light oil or gasoline is generally lower than that of lubricating oil, the fuel is more easily vaporized than lubricating oil. Therefore, regardless of the atmospheric temperature in the crankcase 8 or the like, the fuel mixed in the lubricating oil is more easily vaporized than the lubricating oil. Further, the lower the gas concentration of the fuel in the atmosphere in the crankcase 8, the more easily the fuel mixed in the lubricating oil is vaporized. That is, since the gas concentration of the intake gas flowing through the intake passage is substantially zero, if the intake gas is introduced into the crankcase 8, the fuel mixed in the lubricant can be removed from the lubricant. Therefore, it is possible to suppress the deterioration of the properties of the lubricating oil due to the fuel being mixed into the lubricating oil.

  Here, in this embodiment, since intake gas is introduced into the crankcase 8 from the intake duct 22 through the air introduction passage 63, the fuel mixed in the lubricant is vaporized and removed from the lubricant. be able to.

  In general, the amount of fuel vaporized in the lubricating oil varies depending on the temperature of the atmosphere in the crankcase 8, and the higher the temperature of the atmosphere in the crankcase 8, the more the fuel mixed in the lubricating oil. Easy to vaporize.

  Here, in the present embodiment, the air introduction passage 63 communicates with the intake duct 22 downstream of the compressor 24 of the exhaust turbocharger 23 and upstream of the intake air of the intercooler 29. Since the intake gas flowing through the intake duct 22 in this section is pressurized by the compressor 24, the temperature thereof is high. Therefore, the temperature of the intake gas introduced into the crankcase 8 from the intake duct 22 via the air introduction passage 63 is the same as that when the air introduction passage communicates with the intake duct upstream of the exhaust turbocharger 23 and the intercooler. It is higher than the case where it is communicated with the intake duct at 29 intake downstream. Therefore, according to the present embodiment, since the temperature of the intake gas introduced into the crankcase 8 is high, the amount of fuel vaporized in the lubricating oil can be increased.

  As described above, according to the present embodiment, since the high-temperature intake gas is introduced into the crankcase 8 and the like through the air introduction passage 63, the fuel is mixed in the lubricating oil as a result of the post-injection and the like. However, the mixed fuel can be quickly removed from the lubricating oil. The gas in the crankcase 8 containing the fuel removed from the lubricating oil (hereinafter also referred to as blow-by gas) is introduced into the intake duct upstream of the exhaust turbocharger 23 via the gas recirculation passages 61 and 62. Returned to 25.

  In the present embodiment, the air introduction passage 63 for introducing the intake gas into the crankcase 8 is communicated with the intake duct 22 through which the intake gas pressurized by the compressor 24 flows. The gas recirculation passages 61 and 62 for discharging the blow-by gas from the refrigerant communicate with the intake duct 25 through which the high negative pressure intake gas upstream of the compressor 24 flows. Therefore, when the flow rate control valve 64 is opened, intake gas is effectively introduced into the crankcase 8 and the like via the air introduction passage 63 due to the pressure difference, and via the gas recirculation passages 61 and 62. Thus, the blow-by gas is effectively recirculated. That is, when the air introduction passage 63 and the gas recirculation passages 61 and 62 are both connected to the intake passage having the same pressure, the gas hardly flows through the crankcase 8 or the like, but in this embodiment, the air introduction passage 63 is used. Since this is in communication with the intake passage having a higher pressure than the gas recirculation passages 61 and 62, the gas easily flows through the crankcase 8 and the like.

  By the way, the lubricating oil is harder to vaporize than the fuel as described above, but vaporizes little by little when there is almost no vapor of the lubricating oil in the atmosphere in the crankcase 8 and the valve operating mechanism chamber 12. Therefore, if the intake gas is continuously introduced through the air introduction passage 63, there is almost no lubricating oil vapor in the atmosphere in the crankcase 8 or the like, and the lubricating oil continues to vaporize. Become. Since the lubricating oil vaporized in the atmosphere in the crankcase 8 and the like is returned to the intake duct 25 together with the blow-by gas and then burned in the combustion chamber 7, the exhaust gas properties deteriorate and the amount of lubricating oil decreases. Invite.

  On the other hand, the mixing of the fuel into the lubricating oil occurs particularly noticeably when the post-injection is performed as described above, and hardly occurs at times other than when the post-injection is performed. Therefore, when the post-injection is not performed, the property of the lubricating oil hardly deteriorates due to the mixing of the fuel into the lubricating oil, and at this time, it is not necessary to introduce the intake gas via the air introduction passage 63.

  Therefore, in the present embodiment, the flow rate control valve 64 is opened only during a predetermined period (hereinafter referred to as “when the post injection is performed”, etc.) at the time of post injection execution and after the end of post injection, and at other times the flow control valve. 64 is closed. Thereby, it is possible to prevent the lubricant from being vaporized while preventing the deterioration of the property of the lubricant, and to prevent the deterioration of the property of the exhaust gas and the decrease in the amount of the lubricant. It should be noted that the intake gas is continuously introduced for a predetermined period after the end of the post-injection because the fuel mixed in the lubricant during the post-injection and still remaining in the lubricant after the end of the post-injection is almost completely removed. This is for vaporization.

  Note that the opening degree of the flow rate control valve 64 is not always fully opened at the time of execution of post-injection or the like, but is adjusted according to the post-injection being executed. That is, since the amount of fuel mixed in the lubricating oil varies depending on the post-injection being performed, when the amount of fuel mixed is small, the opening degree of the flow control valve 64 is reduced, and the amount of fuel mixed When the amount is large, the opening degree of the flow control valve 64 is increased. Thereby, vaporization of the lubricating oil can be suppressed while sufficiently promoting the vaporization of the fuel mixed in the lubricating oil.

  Specifically, in the injection pattern shown in FIG. 2 (IV), the injected fuel is less likely to adhere to the cylinder wall surface, so that it is difficult for the fuel to be mixed into the lubricating oil. Even if it exists, the opening degree of the flow control valve 64 is relatively small. On the other hand, in the injection pattern shown in FIG. 2 (III), the injected fuel is likely to reach the cylinder wall surface, so that the fuel is likely to be mixed into the lubricating oil. The opening of is relatively large. In the injection pattern shown in FIG. 2 (II), the amount of fuel mixed into the lubricating oil is intermediate between the two injection patterns, so that the opening degree of the flow control valve 64 is (IV) in FIG. ) Is larger than the opening degree of the flow control valve 64 and smaller than the opening degree of the flow control valve 64 in the case of (III) of FIG.

  Further, the opening degree of the flow control valve is adjusted not only by the post-injection being performed but also by the engine operating state such as the supercharging pressure and the engine speed. That is, the pressure of the intake gas in the intake ducts 22 and 24 changes according to the engine operating state, but is introduced through the air introduction passage 63 in accordance with this pressure change by adjusting the flow rate control valve 64. It is suppressed that the amount of intake gas to be changed.

  In the above description, the flow rate control valve 64 is closed when the post-injection is not performed, but actually, the flow rate control valve 64 is slightly opened even when the post-injection is not performed. That is, blow-by gas is generated in the crankcase 8 and the valve operating mechanism chamber 12 at times other than when post-injection is performed. Such blow-by gas must be returned to the intake passage via the gas recirculation passages 61 and 62. However, if the flow control valve 64 is closed, the intake gas is basically not introduced into the crankcase 8 or the like, and the blow-by gas is blown. Gas stays in the crankcase 8 or the like. Therefore, in order to avoid such a situation, the flow rate control valve 64 is slightly opened even at times other than when post-injection is performed.

  FIG. 3 shows a control routine for controlling the opening and closing of the flow control valve 64, and this routine is performed by interruption every predetermined time interval.

  In step 101, it is determined whether or not the valve opening flag XV of the flow control valve 64 is released. The valve opening flag XV is a flag indicating whether or not the flow control valve 64 is opened, and is set when the flow control valve 64 is opened (XV = 1), and the flow control valve 64 is closed. When set, the set is released (XV = 0). When it is determined in step 101 that the valve opening flag XV is released (XV = 0), that is, when the flow control valve 64 is closed, the routine proceeds to step 102. In step 102, it is determined whether post-injection has been started. When it is determined that the post-injection is not started, the control routine is ended.

  On the other hand, when it is determined in step 102 that post-injection has started, the routine proceeds to step 103. In step 103, the flow control valve 64 is opened, and the introduction of intake gas into the crankcase 8 is started. Next, at step 104, the valve opening flag XV is set (XV = 1), and the control routine is ended.

  When the flow control valve 64 is opened and the valve opening flag XV is set, in the next routine, it is determined in step 101 that the valve opening flag XV of the flow control valve 64 is set, and the routine proceeds to step 105. In step 105, it is determined whether or not post-injection has been completed. If it is determined that post-injection has not been completed, the routine proceeds to step 106. In step 106, the time counter t is set to zero. The time counter t is a counter that represents an elapsed time from the end of the post injection. Next, in step 107, the opening degree of the flow control valve 64 is adjusted. In the opening degree adjustment of the flow control valve 64, the opening degree of the flow control valve 64 is changed according to the engine operation state such as the post injection pattern, the supercharging pressure, and the engine speed as described above.

  Thereafter, when post-injection is completed, the routine proceeds from step 105 to step 108. In step 108, 1 is added to the time counter t (t = t + 1). Next, at step 109, it is determined whether or not the time counter t is smaller than a predetermined time tset, that is, whether or not a predetermined time has elapsed since the end of post-injection. When it is determined that the time counter t is smaller than the predetermined time tset (t <tset), the process proceeds to step 110. In step 110, the opening degree of the flow control valve 64 is adjusted as in step 107, and the control routine is terminated. On the other hand, when it is determined in step 109 that the predetermined time has elapsed from the end of post-injection and the time counter t is equal to or greater than the predetermined time tset, the routine proceeds to step 111. In step 111, the flow control valve 64 is closed and the introduction of the intake gas into the crankcase 8 is stopped. Next, at step 112, the valve opening flag XV is released (XV = 0), and the control routine is terminated.

  In the above-described embodiment, the case where the blow-by gas recirculation device of the present invention is used for an internal combustion engine that performs post-injection as temperature increase control in order to remove particulate matter accumulated on the filter 39 has been described. The blow-by gas recirculation device of the present invention is used if the internal combustion engine is used, or if it is an internal combustion engine (for example, an in-cylinder direct injection internal combustion engine) in which fuel is mixed into the lubricating oil in the oil pan 5. be able to.

Therefore, the blow-by gas recirculation device of the present invention is not limited to an internal combustion engine provided with a particulate filter, but an internal combustion engine provided with various exhaust purification catalysts such as an oxidation catalyst, a three-way catalyst, and an NO _x storage reduction catalyst. Can be used. In this case, for example, an exhaust purification catalyst, the air-fuel ratio of the inflowing exhaust gas is occluded NO _X in the inflowing exhaust gas when the lean, occluded if substantially stoichiometric or rich air-fuel ratio of the inflowing exhaust gas If having _the NO _X storage reduction function of separating and reduced the NO _X which are, it is also possible to use the invention for warm-up control which is performed to remove the sulfur which would be occluded with NO _X. Further, the particulate filter may not carry a catalyst noble metal.

  Furthermore, although the exhaust turbocharger is used as a supercharger in the above embodiment, the present invention is not limited to this, and other superchargers such as a supercharger may be used.

It is a figure which shows the whole internal combustion engine by which the blowby gas recirculation apparatus of this invention is mounted. It is the schematic shown about the fuel-injection pattern which can be implemented with an internal combustion engine in this invention. It is a flowchart which shows the control routine of a flow control valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine body 8 Crankcase 12 Valve mechanism chamber 23 Exhaust turbocharger 29 Intercooler 61 First gas recirculation passage 62 Second gas recirculation passage 63 Air introduction passage 64 Flow control valve

Claims (3)

A supercharger and an intercooler that cools the intake gas pressurized by the supercharger are used in an internal combustion engine provided on an intake passage,
Blow-by gas comprising an air introduction passage for allowing intake gas in the intake passage to flow into the crankcase of the internal combustion engine, and a gas recirculation passage for returning blow-by gas in the crankcase of the internal combustion engine into the intake passage. In the reflux device,
The blow-by gas recirculation device for an internal combustion engine, wherein the air introduction passage communicates with the intake passage downstream of the supercharger and upstream of the intercooler.   2. A flow rate control valve for controlling a flow rate of intake gas flowing through the air introduction passage is provided in the air introduction passage, and the gas recirculation passage communicates with the intake passage on the intake upstream side of the supercharger. The blow-by gas recirculation apparatus according to 1.   The internal combustion engine can perform post-injection in which fuel injection is performed at a timing later than normal main injection, and the flow control valve is opened after the start of the post-injection, and the post-injection is performed. The blow-by gas recirculation device according to claim 2, wherein the flow rate control valve is closed after a predetermined period has elapsed since the end.

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