JP2013185545A - External gas introduction device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an external gas introduction device of an internal combustion engine capable of suppressing the occurrence of heat damage and freezing of a circulation passage and an ejector while maintaining an external gas introduction capability.SOLUTION: An ejector 50 is installed in a circulation passage 420 for circulating intake air from the downstream side to the upstream side of a supercharger 25. By the ejector 50, blow-by gas is sucked and introduced, together with intake air, into an intake air passage 21 through the circulation passage 420. A first passage 421 of the circulation passage 420 connects the ejector 50 to the downstream side of an intercooler 29, and a second passage 422 thereof connects the ejector 50 to the upstream side of the intercooler 29. Then, a switching is performed by opening the first passage 421 and closing the second passage 422 when the outdoor air temperature is high, and by opening the second passage 422 and closing the first passage 421 when the outdoor air temperature is low.

Description

  The present invention relates to an external gas introduction device for an internal combustion engine for introducing external gas such as blow-by gas into an intake passage of the internal combustion engine equipped with a supercharger.

  2. Description of the Related Art As a device mounted on an internal combustion engine, a blow-by gas introducing device that introduces and processes gas leaked into a crankcase from a gap between an inner wall of a cylinder and a piston ring, that is, blow-by gas into an intake passage is known. According to such a blow-by gas introducing device, the blow-by gas is retained in the crankcase by introducing the blow-by gas into the intake passage using the negative pressure generated in the intake passage and burning it in the combustion chamber. Corrosion and oil deterioration of the crankcase can be suppressed.

  By the way, in an internal combustion engine equipped with a supercharger, since the degree of negative pressure generated in the intake passage is low, the processing capacity of such blow-by gas tends to decrease. Therefore, for example, in the one described in Patent Document 1, an ejector is provided in a circulation passage that circulates from the downstream side to the upstream side of the supercharger (strictly, its compressor), and the blow-by gas is passed through the circulation passage and the intake passage through the ejector. To be introduced to. The ejector forcibly causes intake air to flow through the circulation passage by utilizing the difference in pressure inside the intake passage between the upstream and downstream when the turbocharger is supercharged. This is a kind of jet pump that sucks blow-by gas into the ejector. By using such an ejector, the blow-by gas of the crankcase can be introduced into the intake passage even under a situation where the negative pressure in the intake passage is reduced due to the supercharging action of the supercharger. .

JP2011-236825A JP 2011-94557 A

  By the way, when the supercharger is supercharged, the temperature of the intake air may rise and become extremely high. Under such circumstances, when blowby gas processing is performed, there is a risk of causing heat damage such as deformation of the circulation passage or ejector due to the heat of intake air that has become hot.

  On the other hand, an apparatus described in Patent Document 2 is known as a system in which blow-by gas is circulated during supercharging by a supercharger. In the device described in Patent Document 2, intake air is circulated from the circulation passage to the intake passage through the ejector by communicating the ejector and the downstream portion of the intercooler through the circulation passage. For this reason, even if the intake air temporarily rises to the temperature at which the above-mentioned heat damage occurs due to the supercharging action by the supercharger, the intake air after being cooled by the intercooler is introduced into the circulation passage and the ejector. Therefore, the heat damage as described above does not occur. However, on the other hand, when the outside air temperature is extremely low temperature, low-temperature intake air flows through the circulation passage and the ejector, so that moisture contained in the intake air and blow-by gas may freeze in the circulation passage and the ejector. . When such freezing occurs, the flow path through which the intake air and the external gas pass in the circulation passage and the ejector may be narrowed or blocked, resulting in a situation where the blow-by gas treatment is not performed appropriately. In particular, the inside of the ejector is caused by such freezing compared to the intake passage because the flow path of the flowing intake air is narrowed to increase the flow velocity so as to generate a negative pressure for sucking in the blow-by gas. Blockage of the flow path is likely to occur, and its adverse effect cannot be ignored. The occurrence of thermal damage and freezing as described above is not limited to the blow-by gas introduction device, but also to a certain extent even in a device that circulates other external gas different from blow-by gas using an ejector. It happens in the same way.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to circulate intake air to an ejector provided in a circulation passage by a differential pressure upstream and downstream of a supercharger and use the suction action of the ejector. Thus, in the external gas introduction device in which the external gas is introduced into the intake passage, the heat damage and freezing of the circulation passage and the ejector are suppressed while maintaining the external gas introduction capability.

In the following, means for achieving the above object and its effects are described.
The invention according to claim 1 provides an internal combustion engine in which an ejector is provided in a circulation passage that circulates intake air from downstream to upstream of the supercharger, external gas is sucked by the ejector and introduced together with intake air into the intake passage through the circulation passage. In the external gas introducing device, the circulation passage includes a first passage connecting the ejector and the downstream of the intercooler, and a second passage connecting the ejector and the upstream of the intercooler, and the circulation passage. When it is determined that freezing does not occur, the first passage is opened and the second passage is closed, while when it is determined that freezing occurs, the second passage is opened and the first passage is opened. The gist is to execute a switching process for closing the passage.

  According to the above configuration, when it is determined that freezing does not occur in the circulation passage, that is, heat damage such as thermal deformation occurs in the ejector or the circulation passage due to the heat of the intake air that has risen in temperature due to the supercharging action of the supercharger. When there is a risk of occurrence of this, the opening and closing states of the first passage and the second passage are switched through the switching process, and the intake air cooled by the intercooler is introduced into the ejector through the circulation passage. Occurrence can be suppressed. On the other hand, when it is determined that freezing occurs in the circulation passage, that is, intake air whose temperature has decreased due to the cooling action of the intercooler is introduced into the ejector through the circulation passage, and is contained in the intake air and external gas in the ejector and circulation passage. When the moisture to be frozen is likely to freeze, the opening and closing states of the first passage and the second passage are switched through the switching process, and the intake air before being cooled by the intercooler is introduced into the circulation passage. The occurrence of freezing can be suppressed. Parameters for determining whether or not freezing occurs in the circulation passage include, for example, outside air temperature and intake air temperature, or weather information such as rain and snow, and external gas circulated from the circulation passage to the intake passage. And the temperature of the cooling water supplied to the intercooler.

  According to a second aspect of the present invention, in the external gas introduction device for an internal combustion engine according to the first aspect, the switching process is executed when a supercharging pressure of the supercharger is equal to or higher than a predetermined pressure. The gist of the invention is to open the first passage and close the second passage when the number is less.

  In the above configuration, when the differential pressure between the internal pressure upstream and the downstream internal pressure of the turbocharger is large in the intake passage, that is, the amount of external gas sucked into the intake passage and the ejector flowing through the circulation passage is increased as described above. Since the switching process is executed when a simple heat damage or freezing becomes obvious, the heat damage or freezing can be suitably suppressed. On the other hand, when the supercharging pressure is low, the amount of intake gas flowing through the circulation passage through the ejector and the amount of external gas sucked into the ejector is reduced, so that the circulation passage and ejector are frozen by moisture contained in the intake air and external gas. Situations in which the flow path through which intake air or external gas passes in the circulation passage or ejector are narrowed or blocked are unlikely to occur. On the other hand, even if the amount of intake air flowing through the circulation passage via the ejector is small, if the intake air is hot, the possibility is low compared to when the supercharging pressure is high. Harm can occur. Focusing on this point, in the above configuration, when the supercharging pressure is low and the switching process is not executed, the first passage is uniformly opened regardless of whether the lubrication passage is frozen or not. Since the intake passage cooled by the intercooler is introduced into the ejector, the occurrence of such heat damage can be suitably suppressed.

  The invention described in claim 3 is the external gas introduction device for an internal combustion engine according to claim 1 or 2, further comprising an introduction passage for introducing the external gas downstream of the throttle valve of the intake passage. And

  When the supercharging pressure of the supercharger is low, the differential pressure between the internal pressure upstream and downstream of the supercharger in the intake passage becomes small, and the amount of intake air that passes through the ejector and the amount of external gas that is sucked by this This reduces the external gas introduction capability. Further, when the supercharging pressure of the supercharger is low as described above, the opening of the throttle valve is throttled, so that a negative pressure is generated downstream of the throttle valve in the intake passage. According to the above configuration, when the supercharging pressure is low and the external gas introduction capability is reduced, the external gas can be introduced into the intake passage through the introduction passage connected downstream of the throttle valve.

  In addition, while the intake air is supercharged by the supercharger, the throttle valve opening is also throttled to some extent and negative pressure is generated downstream thereof, that is, external gas is introduced into the intake passage via the ejector. At the same time, when the external gas is introduced into the intake passage through the introduction passage, it is desirable to employ the configuration according to claim 2 together. According to such a configuration, by opening the first passage and closing the second passage in the circulation passage, the external gas is introduced into the intake passage through the introduction passage while suppressing the occurrence of the heat damage as described above. Can be introduced.

  Further, as a specific execution mode of the switching process described above, it is desirable to determine the occurrence of freezing of the circulation passage based on the outside air temperature as in the fourth aspect of the invention. That is, when the outside air temperature is relatively high, the first passage is opened and the second passage is closed, while when the outside air temperature is relatively low, the second passage is opened. Then, a configuration is adopted in which the first passage is closed.

  In such switching processing, that is, when switching the open / closed state of the first passage and the second passage based on the outside air temperature, the outside air temperature is directly detected by the outside air temperature sensor, and based on the detected temperature. In addition to switching the open / closed state of each passage, the temperature that changes in correlation with the outside air temperature such as the intake air temperature and the temperature of the engine cooling water at the start of the engine is detected, and based on the detected temperature, The open / closed state can be switched.

  In addition, as a specific execution mode of the switching process based on the outside air temperature described above, a determination for determining whether heat damage or freezing is likely to occur as in the invention described in claim 5. A value is set for the outside air temperature (or its correlation value), and when the outside air temperature is equal to or higher than this judgment value, the first passage is opened and the second passage is closed, while the outside air temperature is less than the judgment value. It is sometimes possible to adopt a configuration in which the second passage is opened and the first passage is closed.

  In addition to such a configuration, for example, when the outside air temperature is equal to or higher than the first determination value at which it is possible to determine that the occurrence of the above-described heat damage is actualized, the first passage is opened and the second passage is closed. The second passage is opened and the first passage is closed when the outside air temperature is set lower than the first determination value and is lower than the second determination value at which it can be determined that the occurrence of freezing described above becomes obvious. To do. Further, when the outside air temperature is equal to or higher than the second determination value and lower than the first determination value, that is, whether heat damage or freezing occurs, the engine operating state such as supercharging pressure or intake air amount at that time Under the circumstances that change accordingly, the open / closed states of the first passage and the second passage may be switched based on the engine operating state in a manner in accordance with such changes.

  According to a sixth aspect of the present invention, in the external gas introducing device for an internal combustion engine according to any one of the first to fifth aspects, the external gas is blowby gas generated in a crankcase of the internal combustion engine. The gist.

  As the external gas introduced into the intake passage, blow-by gas can be exemplified as in the sixth aspect of the invention. Since such blow-by gas is strongly acidic, it causes corrosion in metal members inside the engine such as a crankcase and deterioration of oil. According to the above configuration, the blow-by gas is introduced into the intake passage via the ejector. Therefore, even when supercharging is performed by the supercharger, it can be burned and processed, and at the same time, the thermal damage and freezing of the ejector and the circulation passage that occur during the same processing can be prevented. Can be suppressed. Incidentally, examples of the external gas include EGR gas, gaseous fuel (purge gas) generated in the fuel tank, and the like in addition to such blow-by gas.

The block diagram which shows schematic structure of one Embodiment which actualized this invention to the blow-by gas introduction apparatus. Sectional drawing which shows the internal structure of an ejector. The flowchart which shows the switching process of this embodiment. Sectional drawing which shows the flow of intake air and blow-by gas when a 1st channel | path is open | released by the switching process of this embodiment, and a 2nd channel | path is closed. Sectional drawing which shows the flow of an intake air and blow-by gas when a 2nd channel | path is open | released by the switching process of this embodiment, and a 1st channel | path is closed. Sectional drawing which shows the flow of the intake air and blow-by gas when it is judged that it is not in a supercharging state by the switching process of this embodiment.

  Hereinafter, an embodiment in which an external gas introduction device according to the present invention is embodied as a blow-by gas introduction device that introduces and burns a blow-by gas of a crankcase into an intake passage and processes the same will be described with reference to FIGS. This will be described in detail.

  As shown in FIG. 1, a cylinder head 12 is attached to an upper portion of a cylinder block 11 of the internal combustion engine 10, and a head cover 13 is attached to the upper portion of the cylinder head 12. A crankcase 14 is formed at the lower part of the cylinder block 11, and an oil pan 15 is attached to the lower part of the crankcase 14. The oil pan 15 stores oil for engine lubrication. A piston 17 is accommodated in a cylinder 16 formed inside the cylinder block 11 so as to be able to reciprocate.

  In the intake passage 21 of the internal combustion engine 10, an air cleaner 28 for filtering intake air, an exhaust-driven supercharger 25 (strictly a compressor 26), and intake air to the outside air in order from the upstream (hereinafter simply “upstream”) in the intake flow direction. An intercooler 29, a throttle valve 30 and a surge tank 32 are provided for cooling through heat exchange with each other. The opening degree of the throttle valve 30 is adjusted by a throttle motor 31. Then, through the control of the throttle valve 30, the passage sectional area of the intake passage 21 of the internal combustion engine 10 is adjusted, and the amount of air taken into each cylinder of the internal combustion engine 10 through the intake passage 21 is adjusted.

  The supercharger 25 includes a compressor 26 provided in the intake passage 21 and a turbine wheel provided in the exhaust passage 22. The turbine wheel and the compressor 26 are connected via a shaft 27 so as to be integrally rotatable. When exhaust gas is blown onto the turbine wheel, the turbine wheel and the compressor 26 rotate integrally, whereby the intake air flowing through the intake passage 21 is pumped and forced into the combustion chamber of the internal combustion engine 10. The supercharger 25 has a reduced supercharging degree when the load on the internal combustion engine 10 is reduced and the displacement is reduced, such as when the throttle valve 30 is in a fully closed state, and the opening degree of the throttle valve 30 is large. When the load on the internal combustion engine 10 increases and the displacement increases, the degree of supercharging increases.

  The internal combustion engine 10 is provided with a fuel injection valve (not shown), and fuel injected from the fuel injection valve is supplied into the combustion chamber. In addition, a communication passage 23 is formed inside the internal combustion engine 10 so as to communicate the inside of the head cover 13 and the crankcase 14. In the internal combustion engine 10, unburned gas or combustion gas leaked from the combustion chamber into the crankcase 14 through the clearance between the inner wall of the cylinder 16 and the piston 17, that is, blow-by gas, is introduced into the intake air. A blow-by gas introduction device is provided for combustion and processing.

  This blow-by gas introducing device includes a gas passage 41 into which blow-by gas is introduced from the inside of the crankcase 14, and a circulation passage 420 (421, 422, 423) that circulates intake air from the downstream of the compressor 26 to the upstream in the intake passage 21. The ejector 50 is provided in the circulation passage 420.

  One end of the gas passage 41 is connected to the head cover 13. An oil separator 40 for separating blow-by gas and oil mist is disposed inside the head cover 13, and the gas passage 41 is connected to the head cover 13 via the oil separator 40.

  The circulation passage 420 includes a first passage 421 that connects the ejector 50 and the downstream of the intercooler 29 in the intake passage 21, and a second passage 422 that connects the ejector 50 and the upstream of the intercooler 29 in the intake passage 21. And the third passage 423 connecting the ejector 50 and the upstream side of the compressor 26 in the intake passage 21. These passages 421, 422, and 423 connect the downstream side and the upstream side of the compressor 26 in the intake passage 21 via the ejector 50. Of these passages 421, 422, and 423, the first passage 421 and the second passage 422 are provided with switching valves 43 and 45 for switching the passages 421 and 422 to either an open state or a closed state, respectively. .

  The ejector 50 is a kind of jet pump. Specifically, in the form shown in FIG. 2, the first passage 421, the second passage 422, and the third passage 423 are opened therein. As shown in FIGS. 1 and 2, the first passage 421 and the second passage 422 merge upstream of the ejector 50. The joined passage is opened inside the ejector 50, so that the ejector 50 is connected to the first passage 421 and the second passage 422.

  When the supercharger 25 is supercharged, the inside of the intake passage 21 downstream of the supercharger 25 becomes high pressure, and a pressure difference is generated in the intake passage 21 between the upstream and downstream of the supercharger 25. Become. When the intake air in the intake passage 21 is introduced into the first passage 421 and the second passage 422 during such supercharging, the intake air is introduced into the ejector 50 from the passages 421 and 422. The intake air thus introduced into the ejector 50 flows into the third passage 423 and is then introduced into the intake passage 21 upstream of the supercharger 25. Thus, when the intake air flows through the passages 421, 422, and 423 via the ejector 50, negative pressure is generated in the space 51 inside the ejector 50. The blow-by gas is sucked into the ejector 50 from the gas passage 41 by the negative pressure generated, and further discharged from the ejector 50 into the third passage 423 together with the intake air. As described above, by using the ejector 50, the blow-by gas of the crankcase 14 is supplied to the intake passage 21 even under a situation where the negative pressure of the intake passage 21 is reduced due to the supercharging action of the supercharger 25. Can be introduced. Incidentally, the amount of blow-by gas introduced into the ejector 50 from the gas passage 41 increases as the amount of intake air flowing into the third passage 423 from the first passage 421 or the second passage 422 increases. For example, the pressure increases when the supercharging pressure is high and the differential pressure between the internal pressure upstream and the downstream internal pressure of the supercharger 25 is large in the intake passage 21.

  Further, as shown in FIG. 1, the blow-by gas introducing device introduces an outside air introduction passage 52 for introducing outside air from the intake passage 21 into the head cover 13 and an introduction for introducing blow-by gas downstream of the throttle valve 30 in the intake passage 21. And a PCV passage 55 as a passage. One end of the PCV passage 55 is connected to the head cover 13 via the oil separator 40 in the same manner as the gas passage 41, and the other end is connected to the surge tank 32. A PCV valve 56 is provided at one end of the PCV passage 55, and the blow-by gas flowing through the PCV passage 55 is metered by adjusting the opening of the PCV valve 56.

  Various controls of the internal combustion engine 10 including such a blow-by gas introducing device are executed by the control unit 60. The control unit 60 inputs / outputs signals to / from a CPU that executes various arithmetic processes, a ROM that stores programs and data necessary for the control, a RAM that temporarily stores CPU calculation results, and the like. It has input / output ports and so on.

  Various sensors shown below are connected to the input port of the control unit 60. That is, an air flow meter 61 that detects the intake air amount GA passing through the intake passage 21 and an intake air temperature sensor 62 that detects the temperature Tin of the intake air sucked into the combustion chamber are connected. Further, a throttle sensor 63 for detecting the opening of the throttle valve 30 (throttle opening TA) and a supercharging pressure sensor 64 for detecting a pressure (supercharging pressure P) downstream of the throttle valve 30 in the intake passage 21 are connected. ing. A rotation speed sensor 65 for detecting the engine rotation speed NE, an accelerator sensor 66 for detecting the accelerator pedal depression amount ACCP, and an outside air temperature sensor 67 for detecting the outside air temperature (outside air temperature TO) are connected.

  Based on the detection signals input from the various sensors, the control unit 60 determines the engine operating state such as the engine speed NE and the engine load Q (the amount of air taken into the combustion chamber per cycle of the internal combustion engine 10). To figure out. The engine load is calculated from the intake air amount of the internal combustion engine 10 obtained based on detection signals such as the accelerator pedal depression amount ACCP, the throttle opening degree TA, the intake air amount GA, and the engine rotational speed NE. Then, in accordance with the grasped operation state, operation control of the internal combustion engine 10 such as adjustment control of the intake air amount and the fuel injection amount is executed.

  By the way, when the supercharger 25 is supercharged, the temperature of the intake air may rise and become extremely high. Under such circumstances, when blow-by gas processing is performed, there is a risk that heat damage such as deformation of the circulation passage 420 or the ejector 50 may occur due to the heat of intake air that has become hot.

  In order to avoid the occurrence of such heat damage, for example, the ejector 50 and the downstream portion of the intercooler 29 are communicated with each other through the circulation passage 420 so that the intake air cooled by the intercooler 29 is circulated to the intake passage 21. It is conceivable to adopt a configuration. However, according to such a configuration, although the heat damage as described above does not occur, when the outside air temperature is extremely low, moisture contained in the intake air or blow-by gas freezes in the circulation passage 420 or the ejector 50. May occur. In particular, the inside of the ejector 50 generates a negative pressure for sucking the blow-by gas by narrowing the flow path of the flowing intake air and increasing the flow velocity. The resulting flow path blockage is likely to occur, and its adverse effect cannot be ignored.

  Therefore, in the present embodiment, switching processing for switching the open / closed states of the first passage 421 and the second passage 422 is performed by controlling the switching valves 43 and 45 by the control unit 60. Hereinafter, the procedure of this switching process will be described with reference to FIG. Note that the series of processing shown in FIG. 3 is repeatedly executed by the control unit 60 at predetermined intervals during engine operation.

  As shown in FIG. 3, in this series of processes, it is first determined whether or not the engine is in a supercharging state (step S110). Here, whether or not the engine is in the supercharging state is determined based on whether or not the supercharging pressure P detected from the supercharging pressure sensor 64 is equal to or higher than the determination pressure Pa.

  Here, when the supercharging pressure is high, that is, when the differential pressure between the internal pressure upstream of the compressor 26 and the downstream internal pressure in the intake passage 21 is large, the intake and gas passages that flow through the passages 421, 422, and 423 via the ejector 50 The amount of blow-by gas sucked into the ejector 50 from 41 increases. Under such circumstances, problems such as heat damage and freezing that occur in the ejector 50 and the passages 421, 422, and 423 as described above are likely to become obvious. In view of these points, the determination pressure Pa is set in advance to a value at which it is possible to determine that the above-described thermal damage or freezing is likely to occur when the supercharging pressure P is equal to or higher than the determination pressure Pa. ing.

  Then, if it is determined that the supercharging pressure P is equal to or higher than the determination pressure Pa, that is, it is in the supercharging state (step S110: YES), it is next determined whether or not the outside air temperature TO is less than the determination value TOa (step). S120). Note that the detected value by the outside air temperature sensor 67 is used as a parameter for performing the determination in step S120.

  Here, when the outside air temperature is high, the intake air that is already hot rises in temperature due to the supercharging action of the supercharger 25 and becomes further hot, so that the heat damage described above may occur due to the heat of the intake air. There is. On the other hand, when the outside air temperature is low, although the temperature rises to some extent due to the supercharging action of the supercharger 25, the low-temperature intake air is cooled by the intercooler 29. And the moisture contained in the blow-by gas may freeze. In consideration of these points, the determination value TOa is a value at which it is possible to determine that the above-described heat damage may occur when the outside air temperature TO is equal to or higher than the determination value TOa. When the value is less than the determination value TOa, the value is set in advance so that it can be determined that there is a possibility of freezing as described above.

  When it is determined that the outside air temperature TO is equal to or higher than the determination value TOa (step S120: NO), the first passage 421 is opened and the second passage 422 is opened because there is a possibility that the above-described heat damage may occur. Close (step S130). In step S130, the switching valve 43 is opened and the switching valve 45 is closed. Therefore, the intake air cooled by the intercooler 29 is introduced into the circulation passage 420 and the ejector 50.

  On the other hand, if it is determined that the outside air temperature TO is less than the determination value TOa (step S120: YES), the first passage 421 is closed and the second passage 422 is opened because there is a possibility that freezing as described above may occur. (Step S140). In step S140, the switching valve 43 is closed and the switching valve 45 is opened. Therefore, intake air before being cooled by the intercooler 29, in other words, intake air whose temperature has been increased by the supercharging action of the supercharger 25 is introduced into the circulation passage 420 and the ejector 50. As described above, the open / closed state of the first passage 421 and the second passage 422 is switched by performing any one of the processes of Step S130 and Step S140.

  On the other hand, when the supercharging pressure is low, that is, when the differential pressure between the internal pressure upstream of the compressor 26 and the downstream internal pressure is small in the intake passage 21, the intake or gas passage 41 flowing through the passages 421, 422, 423 via the ejector 50. Therefore, the amount of blow-by gas sucked into the ejector 50 is reduced, so that the above-described problems such as heat damage and freezing are not easily realized.

  Here, when such a supercharging pressure is low, the problems such as heat damage and freezing are difficult to be realized, but the extent of occurrence is as follows. First, under such circumstances, the amount of intake air flowing through the passages 421, 422, and 423 via the ejector 50 and the amount of blow-by gas sucked into the ejector 50 is reduced. Therefore, the passages 421, 422, 423 and the ejector 50 are frozen by moisture contained in the intake air and the blow-by gas, so that the flow paths through which the intake air and blow-by gas pass in the passages 421, 422, 423 and the ejector 50 are narrowed. Or the situation of blockage is unlikely to occur. On the other hand, even when there is little intake air flowing through the passages 421, 422, and 423 via the ejector 50, if the intake air is at a high temperature, the possibility is low compared to when the supercharging pressure is high, Thermal damage as described above occurs.

  Focusing on this point, in the present embodiment, when the supercharging pressure is low, that is, when the supercharging pressure P is less than the determination pressure Pa (step S110: NO), the first passage is uniform regardless of the outside air temperature. 421 is opened to close the second passage 422 (step S130). In this way, the intake air cooled by the intercooler 29 is introduced into the ejector 50 even when the supercharging pressure P is low.

  Next, the operation of this embodiment will be described. First, when the supercharging pressure is high and the outside air temperature is high (step S110: YES, step S120: NO in FIG. 3), the first passage 421 is opened and the second is switched by the switching process. Since the passage 422 is closed (step S130), intake air is introduced from the intake passage 21 into the first passage 421 as shown in FIG. The intake air thus introduced into the first passage 421 flows into the third passage 423 via the ejector 50 and then is introduced into the intake passage 21 upstream of the compressor 26. In addition, a negative pressure is generated inside the ejector 50 due to the flow of intake air in the passages 421 and 423 made through the ejector 50, whereby blow-by gas is introduced into the ejector 50 through the gas passage 41. The blow-by gas thus introduced into the ejector 50 flows into the third passage 423 together with the intake air flow and is introduced into the intake passage 21 upstream of the compressor 26.

  Here, even if the intake air becomes hot immediately after the compressor 26 in the intake passage 21 due to the supercharging action or the outside air temperature by the supercharger 25, the first passage in the intake passage 21 further downstream thereof. In the connection portion with 421, the intake air is cooled by the intercooler 29, and the temperature is lowered to a low temperature. For this reason, when the intake air flows through the passages 421 and 423 via the ejector 50, excessive heat of the intake air does not act on the ejector 50 and the passages 421 and 423, and the occurrence of the heat damage is suppressed. be able to.

  When the supercharging pressure is high and the outside air temperature is low (step S110: YES, step S120: YES in FIG. 3), the second passage 422 is opened by the switching process and the first is performed. Since the passage 421 is closed (step S140), the intake air is introduced into the second passage 422 from the intake passage 21, as shown in FIG. The intake air thus introduced into the second passage 422 flows into the third passage 423 via the ejector 50 and then is introduced into the intake passage 21 upstream of the compressor 26. In addition, a negative pressure is generated inside the ejector 50 due to the flow of the intake air in the passages 422 and 423 made through the ejector 50, whereby blow-by gas is introduced into the ejector 50 through the gas passage 41. The blow-by gas thus introduced into the ejector 50 flows into the third passage 423 together with the intake air flow and is introduced into the intake passage 21 upstream of the compressor 26.

  Here, even if the intake air has a low temperature downstream of the intercooler 29 in the intake passage 21 due to the outside air temperature or the cooling action by the intercooler 29, the intake passage 21 is connected to the second passage 422 in the upstream intake passage 21. Since the connection portion is not cooled by the intercooler 29 and immediately after the temperature rises due to the supercharging operation by the supercharger 25, the temperature is higher than that downstream of the intercooler 29. For this reason, when the intake air flows through the passages 422 and 423 via the ejector 50, the low-temperature intake air does not flow into the ejector 50 and the passages 422 and 423, and the blow-by gas is excessively cooled by the intake air. The occurrence of freezing can be suppressed.

  When the supercharging pressure is high, no negative pressure is obtained downstream of the throttle valve 30 in the intake passage 21, so blow-by gas is not introduced into the PCV passage 55 connected downstream of the throttle valve 30. Therefore, when the supercharging pressure by the supercharger 25 is high as shown in FIGS. 4 and 5, the intake air that has become high pressure due to the supercharging action of the supercharger 25 passes through the passages 421, 422, 423. And blow-by gas is sucked into the ejector 50 only through the gas passage 41. Therefore, the amount of these intake air and blow-by gas increases, and the problems such as heat damage and freezing are likely to become obvious.

  When the supercharging pressure is low (step S110 in FIG. 3: NO), the first passage 421 is opened and the second passage 422 is closed by the switching process (step S130). As shown, intake air is introduced into the first passage 421 from the intake passage 21. Then, by switching the open / closed states of the passages 421 and 422 in this way, the intake air cooled by the intercooler 29 flows through the passages 421 and 423 via the ejector 50, as in the situation shown in FIG. become.

  Here, when the supercharging pressure is low, the opening of the throttle valve 30 is set to a small opening, so that a negative pressure can be obtained downstream of the throttle valve 30 in the intake passage 21, and the PCV passage 55. Also blow-by gas will be introduced. Therefore, the amount of intake air introduced from the intake passage 21 to the first passage 421 when the supercharging pressure is low as compared to when the supercharging pressure shown in FIGS. 4 and 5 is high. And the blow-by gas sucked into the ejector 50 through the gas passage 41 is reduced by the amount of blow-by gas flowing into the PCV passage 55. And even when the supercharging pressure is low, the intake air cooled by the intercooler 29 is introduced into the ejector 50, so that the heat damage in the ejector 50 and the passages 421 and 423 can be prevented. Can be suppressed.

According to the embodiment described above, the following effects can be obtained.
(1) According to the present embodiment, when the outside air temperature is high, that is, the ejector 50 and the circulation passage 420 are thermally deformed by the heat of the intake air that has risen in temperature due to the supercharging action of the supercharger 25 and becomes high temperature. When there is a risk of heat damage, the open / closed states of the first passage 421 and the second passage 422 are switched so that the intake air cooled by the intercooler 29 is introduced into the ejector 50 through the passages 421 and 423. Therefore, the occurrence of such heat damage can be suppressed. On the other hand, when the outside air temperature is low, that is, the intake air whose temperature has decreased due to the cooling action of the intercooler 29 is introduced into the ejector 50 through the circulation passage 420, and the intake air or blow-by gas is introduced into the ejector 50 or the circulation passage 420. When the moisture contained in the air is frozen, the first passage 421 and the second passage 422 are opened and closed so that the intake air before being cooled by the intercooler 29 is introduced into the passages 422 and 423. Since it is switched, the occurrence of such freezing can be suppressed.

  (2) In this embodiment, when the differential pressure between the internal pressure upstream and the downstream internal pressure of the compressor 26 is large in the intake passage 21, that is, the intake air flowing through the passages 421, 422, and 423 and the blow-by gas sucked into the ejector 50 When the amount of heat increases and the heat damage and freezing as described above are likely to become apparent, the switching process based on the outside air temperature of the first passage 421 and the second passage 422 is executed. Can be suitably suppressed. On the other hand, when the supercharging pressure is small and the switching process (step S110, step S130 or step S140 in FIG. 3) performed when the supercharging pressure is low and the supercharging pressure is high is not executed. The first passage 421 is uniformly opened and the second passage 422 is closed regardless of the outside air temperature, and the intake air cooled by the intercooler 29 is introduced into the ejector 50. The occurrence of this can be suitably suppressed.

  (3) When the supercharging pressure of the supercharger 25 is low, the differential pressure between the internal pressure upstream of the supercharger 25 and the internal pressure downstream of the supercharger 25 in the intake passage 21 becomes small, and the amount of intake air passing through the ejector 50 and the ejector Since the amount of blow-by gas sucked into 50 is reduced, the introduction ability of blow-by gas is reduced. Further, when the supercharging pressure of the supercharger 25 is low as described above, the opening of the throttle valve 30 is throttled, so that a negative pressure is generated downstream of the throttle valve 30 in the intake passage 21. According to the present embodiment, when the supercharging pressure is low and the blow-by gas introduction ability is reduced, the blow-by gas is introduced into the intake passage 21 through the PCV passage 55 as the introduction passage connected downstream of the throttle valve 30. can do.

  In the situation where the intake air is supercharged by the supercharger 25, while the opening of the throttle valve 30 is throttled to some extent and a negative pressure is generated downstream thereof, the blow-by gas is introduced into the intake passage via the ejector 50. When the blow-by gas is introduced into the intake passage 21 through the PCV passage 55, the first passage 421 is opened and the second passage 422 is closed. The blow-by gas can be introduced into the intake passage 21 through the PCV passage 55 while suppressing the occurrence of the above.

  (4) Since blowby gas is strongly acidic, it causes corrosion inside the engine such as the crankcase 14 and deterioration of oil. According to this embodiment, blowby gas is introduced into the intake passage 21 via the ejector 50. Therefore, even when supercharging by the supercharger 25 is performed, this can be burned and processed, and the heat of the ejector 50 and the passages 421, 422, and 423 generated during the processing is also obtained. Harm and freezing can be suppressed.

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
In the above embodiment, the supercharging pressure sensor disposed downstream of the throttle valve 30 in the intake passage 21 as the supercharging pressure P for determining whether or not it is in the supercharging state in step S110 of FIG. The detection value from 64 was adopted. As the supercharging pressure P, for example, a supercharging pressure sensor 64 is provided in the intake passage 21 downstream of the supercharger 25 and upstream of the throttle valve 30, and a detected value from the supercharging pressure sensor 64 is provided. Can be adopted. Further, a supercharging pressure sensor 64 is provided upstream of the supercharger 25 in the intake passage 21, and a value obtained by correcting the detected value from the supercharging pressure sensor 64 based on the supercharging capability of the supercharger 25 is obtained. You may make it employ | adopt as the supercharging pressure P. FIG.

  A value other than the detection value from the supercharging pressure sensor 64 may be adopted as the supercharging pressure P. For example, the boost pressure P may be estimated based on the engine operating state such as the engine speed NE and the engine load Q, and this value may be adopted.

  In the above embodiment, when it is determined in step S110 in FIG. 3 that the supercharging pressure P is less than the determination pressure Pa, the first passage 421 is opened and the second passage 422 is closed. (Step S130), conversely, the second passage 422 may be opened and the first passage 421 may be closed. Depending on such a form, the effects (1), (3), and (4) obtained by the above embodiment can be obtained.

  -When it is judged in step S110 of FIG. 3 that the supercharging pressure P is less than the judgment pressure Pa, both the first passage 421 and the second passage 422 may be opened. Any of the passages may be closed. Even in such a form, the effects (1), (3), and (4) obtained by the above embodiment can be obtained.

  In the above embodiment, when switching between the open / closed states of the first passage 421 and the second passage 422, it is determined whether or not the engine is in the supercharged state (step S110 in FIG. 3), and the outside air temperature TO Is determined whether or not the temperature is high (step S120). Instead of this, the determination regarding the supercharging state is omitted, and only the determination of whether or not the outside air temperature TO is high is made, and then the first passage 421 and the second passage 422 are based on the determination. Switching between open and closed states may be performed. Even in such a form, the effects (1), (3), and (4) obtained by the above embodiment can be obtained.

  In the above embodiment, the outside air temperature of the internal combustion engine 10 is used as the outside air temperature TO for determining whether or not any of the heat damage and freezing described above in step S120 in FIG. 3 is likely to occur. The detection value from the outside air temperature sensor 67 that is directly detected is employed. In addition to this, the outside air temperature TO is detected by detecting a temperature that changes in correlation with the outside air temperature such as the intake air temperature or the temperature of the engine cooling water at the time of starting the engine, and the outside air temperature TO is estimated from the detected temperature. It is possible to adopt this value. Further, the detected temperature may be used as a parameter for performing the determination in step S120 as it is without estimating the outside air temperature TO instead of the outside air temperature TO. The intake air temperature sensor for detecting the intake air temperature may be provided downstream of the intercooler in the intake passage as in the intake air temperature sensor 62 of the above embodiment, or provided upstream of the intercooler. May be used.

  In the above embodiment, in step S120 in FIG. 3, it is determined whether or not any of the above-described heat damage or freezing is likely to occur by comparing the outside air temperature TO with the determination value TOa. I was doing. The determination mode performed based on the outside air temperature is not limited to this, and for example, the following determination mode can be adopted. That is, as the first determination value, a value that can be determined that the occurrence of the above-described heat damage becomes apparent when the outside air temperature is equal to or higher than the first determination value is set, and the first determination value is the first determination value. Is set to a value that can be determined to be the occurrence of freezing described above when the outside air temperature is lower than the second determination value. When the outside air temperature is equal to or higher than the first determination value, the first passage 421 is opened and the second passage 422 is closed, while when the outside air temperature is lower than the second determination value, the second passage 421 is closed. The passage 422 is opened and the first passage 421 is closed. Further, when the outside air temperature is equal to or higher than the second determination value and lower than the first determination value, that is, whether heat damage or freezing occurs, the engine operating state such as supercharging pressure or intake air amount at that time Under the circumstances that change accordingly, the open / closed states of the first passage 421 and the second passage 422 are switched based on the engine operating state in a manner in accordance with such changes. Also according to such a determination mode, it is determined whether or not any of the above-described heat damage and freezing is likely to occur, and the first passage 421 and the second passage 422 are opened / closed based on the determination. Can be switched.

  In the above embodiment, it is determined in step S120 in FIG. 3 whether or not any of the above-described heat damage or freezing is likely to occur based on the outside air temperature TO. However, for such determination, for example, intake air temperature, weather information such as rain and snow, the amount of external gas circulated from the circulation passage to the intake passage, the humidity of the outside air, the temperature of the cooling water supplied to the intercooler, etc. It is also possible to carry out with parameters other than the outside temperature.

  The blow-by gas processing can be performed by omitting the PCV passage 55 and using only the circulation passage 420 and the ejector 50. Depending on such a form, the effects (1), (2), and (4) obtained by the above embodiment can be obtained.

  In order to switch the open / closed state of the first passage 421 and the second passage 422, the switching valves 43 and 45 are provided in the passages 421 and 422, respectively, but the passages 421 and 422 merge. A common flow path switching valve is provided at the site, the first passage 421 is opened by the valve and the second passage 422 is closed, and the second passage 422 is opened and the first passage 421 is opened. You may make it switch between the states closed.

  ・ The above-mentioned problems such as heat damage and freezing are not limited to the blow-by gas introduction device, but are similar to some extent even in devices that circulate other external gases different from blow-by gas using an ejector. To occur. For this reason, the external gas introducing device of the present invention can be applied to devices other than the blow-by gas introducing device as in the above embodiment. For example, the present invention can be applied to an apparatus that introduces EGR gas, gaseous fuel (purge gas) generated in a fuel tank, etc., into the intake passage as external gas. According to such a form, the effect of (1)-(3) obtained by the said embodiment can be acquired.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Cylinder block, 12 ... Cylinder head, 13 ... Head cover, 14 ... Crankcase, 15 ... Oil pan, 16 ... Cylinder, 17 ... Piston, 21 ... Intake passage, 22 ... Exhaust passage, 23 ... Station Passage, 25 ... supercharger, 26 ... compressor, 27 ... shaft, 28 ... air cleaner, 29 ... intercooler, 30 ... throttle valve, 31 ... throttle motor, 32 ... surge tank, 40 ... oil separator, 41 ... gas passage, 43, 45 ... switching valve, 50 ... ejector, 51 ... space, 52 ... outside air introduction passage, 55 ... PCV passage, 56 ... PCV valve, 60 ... control unit, 61 ... air flow meter, 62 ... intake air temperature sensor, 63 ... throttle Sensor, 64 ... Supercharging pressure sensor, 65 ... Rotational speed sensor, 66 ... Accelerator sensor, 67 ... Outside air temperature Capacitors, 420 ... circulation passage, 421 ... first passage, 422 ... second passage, 423 ... third passageway.

Claims (6)

In an external gas introduction device for an internal combustion engine, an ejector is provided in a circulation passage that circulates intake air from downstream to upstream of a supercharger, and external gas is sucked by the ejector and introduced into the intake passage through the circulation passage together with intake air.
The circulation path includes a first path that connects the ejector and the downstream of the intercooler, and a second path that connects the ejector and the upstream of the intercooler,
When it is determined that freezing does not occur in the circulation passage, the first passage is opened and the second passage is closed, while when it is determined that freezing occurs, the second passage is opened and the second passage is opened. An external gas introduction device for an internal combustion engine, wherein a switching process for closing the first passage is performed. The external gas introduction device for an internal combustion engine according to claim 1,
The switching process is executed when the supercharging pressure of the supercharger is equal to or higher than a predetermined pressure, and when the pressure is lower than the predetermined pressure, the first passage is opened and the second passage is closed. An external gas introducing device for an internal combustion engine characterized by the above. The external gas introduction device for an internal combustion engine according to claim 1 or 2,
An external gas introduction device for an internal combustion engine, further comprising an introduction passage for introducing the external gas downstream of the throttle valve in the intake passage. The external gas introduction device for an internal combustion engine according to any one of claims 1 to 3,
The external gas introduction device for an internal combustion engine, wherein the occurrence of freezing of the circulation passage is determined based on an outside air temperature during the switching process. The external gas introducing device for an internal combustion engine according to claim 4,
In the switching process, when the outside air temperature is equal to or higher than a determination value, the first passage is opened and the second passage is closed, while the second air temperature is less than the determination value. An external gas introduction device for an internal combustion engine, wherein a passage is opened to close the first passage. The external gas introduction device for an internal combustion engine according to any one of claims 1 to 5, wherein the external gas is blow-by gas generated in a crankcase of the internal combustion engine.