JP6021553B2 - Intake device for internal combustion engine - Google Patents

Description

  The present invention relates to an intake device that supplies combustion air to an internal combustion engine for a vehicle, and more particularly to an intake device that can prevent clogging of an intake system due to snow.

  2. Description of the Related Art Conventionally, an air cleaner is generally provided in an intake system of an internal combustion engine to remove dust or dirt in the air supplied to a combustion chamber. For example, Patent Document 1 describes a diesel engine including an air cleaner on the compressor upstream side of a turbocharger interposed in an intake passage.

  In addition, in order to improve the output and efficiency of the internal combustion engine, as the combustion air, outside air having a low temperature is introduced from the outside of the engine compartment (hereinafter referred to as “outside air intake”). For example, Patent Document 2 describes an engine intake device in which an air intake port of an intake duct is opened behind a front grill provided at a front portion of a vehicle.

JP 2008-261287 A (page 4-5, FIG. 1) JP 2011-58461 A (page 4-6, FIGS. 1 and 4)

  If there is snowfall at an outside temperature of -15 ° C. or less, it often becomes powdery and light snow particles, and it is easy to enter the intake system like dust and dust. In the prior art intake system, if a large amount of such fine snow is sucked in, the snow accumulates on the front surface of the air cleaner element, obstructing the intake of combustion air, and the operation of the internal combustion engine becomes unsatisfactory. It was.

  For example, when the vehicle continues to run for a long time under a low outside air condition where the outside air temperature is about −15 ° C. or lower, substantially the entire front surface of the air cleaner element is caused by snow accumulated inside the air cleaner case. It can happen that it is blocked.

  In particular, in a vehicle employing outdoor air intake, the intake intake port opens toward the outside of the vehicle, so that it is easy to suck snow and the air cleaner is easily clogged by the snow.

  In particular, in the case of a diesel engine, the intake air amount is not limited for the required output as in a gasoline engine, and the intake air amount is always large. Furthermore, in order to improve the output and exhaust gas performance of recent diesel engines, it is common knowledge to have a turbocharger, and the amount of intake air further increases. For this reason, blockage due to snow is more likely to occur.

  Furthermore, in the case of an engine equipped with a turbocharger, when the air cleaner becomes clogged and normal operation cannot be performed, the engine continues to run even if the fuel supply is stopped. is there. In other words, even if no fuel is supplied, engine oil is sucked into the intake passage that has become negative pressure from the sliding bearing portion of the turbocharger, etc., and spontaneously ignites in the combustion chamber using the engine oil as fuel. It ends up.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an intake device for an internal combustion engine that can prevent the air cleaner from being clogged with snow.

An intake device for an internal combustion engine according to the present invention is an intake device for an internal combustion engine having an intake passage that takes in air and supplies the air to a combustion chamber, wherein the intake port takes in the air into the intake passage, and the air intake portion An air cleaner that allows the air taken in from the air to pass through, a turbocharger that compresses the air that has passed through the air cleaner, and a part of the air compressed by the turbocharger to flow upstream to the air cleaner comprising a passage, wherein the return passage is characterized Rukoto is connected to the lower portion of the air cleaner case for housing the air cleaner.

  According to the air intake device of the present invention, a part of the air compressed and heated by the supercharger is returned to the upstream side of the air cleaner, so that the snowflakes attached to the air cleaner can be melted by the high-temperature air. . Therefore, even when a large amount of snow is inhaled, the air cleaner can be prevented from being clogged.

1 is a schematic configuration diagram of an internal combustion engine including an intake device according to an embodiment of the present invention. It is a schematic block diagram which shows the air cleaner of the intake device which concerns on embodiment of this invention. It is a flowchart which shows the control outline | summary of the internal combustion engine which concerns on embodiment of this invention. It is a flowchart which shows the modification of a control method same as the above. It is a graph which shows the driving test result of the vehicle provided with the supercharger.

  Hereinafter, an intake device for an internal combustion engine according to an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a schematic configuration of a diesel engine 1 including an intake device 10 according to an embodiment of the present invention.

  As shown in FIG. 1, a diesel engine 1 includes an engine body 2, an intake device 10 having an intake path for supplying combustion air to the engine body 2, and an exhaust path 30 for exhausting exhaust gas from the engine body 2. . The diesel engine 1 is mounted on an automobile and serves as a driving source for traveling.

  The engine body 2 includes a plurality of cylinders 3 constituting a combustion chamber of an internal combustion engine, and a piston 4 that reciprocates inside the cylinder 3. Each cylinder 3 communicates with an intake passage 18 constituting an intake path of the intake device 10 via an intake port 7. And in each intake port 7, the intake valve 5 is arrange | positioned so that opening and closing is possible. Each cylinder 3 communicates with an exhaust passage 33 constituting an exhaust path 30 via an exhaust port 8. And in each exhaust port 8, the exhaust valve 6 is arrange | positioned so that opening and closing is possible.

  The engine body 2 is provided with an injector 41 that injects fuel into the cylinders 3. The injector 41 includes an actuator and is controlled by a drive signal from an electronic control unit 40 (ECU).

  The intake device 10 supplies combustion air formed by sequentially connecting an air intake port 14a, an air cleaner 11, a compressor 12a of a turbocharger 12, an intercooler 13, an intake throttle valve 42, and an intake port 7 of the cylinder 3. An intake path for supplying to the cylinder 3 is provided.

  The air intake 14 a is an opening formed in the outside air introduction duct 14. The air intake port 14a is disposed in front of the vehicle so as to take in outside air having a low temperature from the outside of the engine compartment, and opens outward.

  The air cleaner 11 is for passing inhaled air and removing dust and dirt in the air, and is disposed inside the air cleaner case 15. The interior of the air cleaner case 15 is partitioned by the air cleaner 11 into an upstream front chamber 20 and a downstream rear chamber 21. The front chamber 20 of the air cleaner case 15 communicates with an outside air introduction duct 14 connected to the air cleaner case 15, and the rear chamber 21 communicates with an intake passage 16 through which air flows to the engine body 2 side. .

  The compressor 12 a of the turbocharger 12 increases the mass flow rate of air sent to each cylinder 3, that is, supercharges to improve the output and efficiency of the engine, and is installed in the intake path downstream of the air cleaner 11. Has been. The compressor 12a is disposed coaxially with the exhaust turbine 12b provided in the exhaust path 30, and uses the exhaust pressure of the engine body 2 as a drive source. Instead of the turbocharger 12, a supercharger that uses a drive source other than the exhaust pressure, for example, a mechanical supercharger that uses the power of the engine body 2 may be used.

  The intercooler 13 is an intake air cooler for cooling the air compressed and heated by the compressor 12a to increase the charging efficiency, and is interposed in the intake passage on the downstream side of the compressor 12a.

  The intake throttle valve 42 adjusts the amount of combustion air sucked into each cylinder 3 and is interposed in the intake passage 18 on the downstream side of the intercooler 13. The intake throttle valve 42 is driven and controlled by the electronic control unit 40.

  The intake device 10 also includes a return passage 19 that connects the downstream intake passage of the compressor 12a of the turbocharger 12 and the upstream intake passage of the air cleaner 11 so that air can flow therethrough. Specifically, the return passage 19 has one end connected to the intake passage 17 on the downstream side of the compressor 12 a and the other end connected to the front chamber 20 side of the air cleaner case 15.

  Here, the one end of the return passage 19 is preferably connected to the upstream side of the intercooler 13. Thereby, high-temperature air before being cooled by the intercooler 13 can be caused to flow through the return passage 19. Further, the other end of the return passage 19 may be connected anywhere as long as it is upstream of the air cleaner 11. For example, the return passage 19 may be connected to the outside air introduction duct 14.

  The return passage 19 is provided with a control valve 48 for adjusting the amount of air flowing through the passage. The control valve 48 is driven and controlled by the electronic control unit 40. In such a configuration, by opening the control valve 48, a part of the air pressurized and heated by the compressor 12a can be returned to the upstream side of the air cleaner 11 (hereinafter referred to as "warm air return" as appropriate). say.).

  The air on the downstream side of the compressor 12a is compressed by the compressor 12a and has a high pressure. Therefore, when the warm air is returned, no other power is required to return the air. The flow passage cross-sectional area through which the air inside the return passage 19 flows is smaller than the flow passage cross-sectional area of the intake passage 17. Thereby, it can suppress that the intake_air | air_intake to the engine main body 2 runs short by excessive warm air return.

  The exhaust passage 30 discharges exhaust gas after explosive combustion inside each cylinder 3 to the outside of the system, and from the exhaust passage 33 connected to each exhaust port 8, the exhaust turbine 12 b, the catalyst 31, the muffler The devices 32 are sequentially connected.

  As described above, the exhaust turbine 12b drives the compressor 12a using the pressure of the exhaust gas. The catalyst 31 mainly oxidizes hydrocarbons (HC) in the exhaust gas by catalytic reaction to reduce particulate matter (PM). The silencer 32 reduces exhaust discharge noise.

  The exhaust passage 30 is formed with an exhaust bypass passage 35 that connects the exhaust passage 33 and the exhaust passage 34 to bypass the exhaust turbine 12b. A wastegate valve 43 is interposed in the exhaust bypass passage 35. The wastegate valve 43 is operated by a drive signal from the electronic control unit 40, thereby adjusting the exhaust pressure supplied to the exhaust turbine 12b and controlling the supercharging pressure.

  The electronic control unit 40 includes a microcomputer having a CPU and the like, performs predetermined arithmetic processing, and controls the operation of the diesel engine 1. As described above, the electronic control unit 40 drives and controls the injector 41, the intake throttle valve 42, the wastegate valve 43, and the control valve 48. Furthermore, detection values from various sensors 44 to 47 are input to the input terminal of the electronic control unit 40.

  The temperature sensor 45 detects the temperature of the taken outside air and is disposed in the outside air introduction duct 14. The snow sensor 46 is, for example, an optical sensor that detects the presence of snow, and is disposed in the front chamber 20 of the air cleaner case 15. The pressure sensor 47 detects the air pressure downstream of the air cleaner 11 and upstream of the compressor 12a, and is disposed in the intake passage 16 that connects the air cleaner 11 and the compressor 12a. The pressure sensor 44 detects the exhaust pressure and is disposed in the exhaust passage 34.

  When a vehicle equipped with the diesel engine 1 having the above configuration is operated at a low outside air temperature of, for example, about −15 ° C. or less, snow enters the intake path of the intake device 10 from the outside air intake port 14a. May come.

  Here, the snow sucked into the intake device 10 is a relatively small and light snowflake. However, the snow is not limited to snowfall, but snow covered on the road surface, or so-called hoarfrost or fine ice in which moisture in the air freezes. Etc. are also included.

  As described above, in the prior art engine, the snow that has entered the intake system adheres to the air cleaner and obstructs the flow of the intake air, resulting in a shortage of combustion air, resulting in a malfunction of the engine. There was a point.

However, in the intake device 10 according to the present embodiment, a part of the air that has been compressed by the compressor 12a of the turbocharger 12 and has a high temperature is allowed to pass through the return passage 19 to be passed through the air cleaner 11.
It is possible to melt the snow that has entered by using the heat of the air.

  For example, by combining the high-temperature air flowing in from the return passage 19 with the air taken in from the air intake port 14a, it is possible to melt the snowflake that flows along with the air. Further, by applying warm air returned through the return passage 19 to the snowflakes accumulated on the inner wall surfaces of the air cleaner 11 and the air cleaner case 15, the snowflakes can be melted. Moreover, the snowflakes adhering thereto can be melted by heat transfer from the air cleaner 11 and the air cleaner case 15 that have been warmed by returning to warm air. Thus, according to the intake device 10 according to the present embodiment, the air cleaner 11 can be prevented from being blocked by snow.

  Next, the configuration around the air cleaner 11 will be described in detail with reference to FIG. FIG. 2 is a perspective view showing a schematic configuration in the vicinity of the air cleaner 11 of the intake device 10 (see FIG. 1).

  As shown in FIG. 2, the air cleaner 11 is disposed inside an air cleaner case 15 having a substantially box shape. The interior of the air cleaner case 15 is partitioned by the air cleaner 11, and an upstream front chamber 20 and a downstream rear chamber 21 are formed. Further, a discharge hole 15d for discharging moisture is formed in the bottom surface 15j of the air cleaner case 15.

  An inlet 15 a that is an opening through which air flows is formed on a side surface 15 e that faces the air cleaner 11 on the upstream side of the air cleaner case 15. The outside air introduction duct 14 is connected to the inlet 15 a so that the internal passage communicates with the front chamber 20.

  On the other hand, on the side surface 15f facing the air cleaner 11 on the downstream side of the air cleaner case 15, an outlet 15b which is an opening through which air flows out is formed. An intake passage 16 connected to the compressor 12a of the turbocharger 12 (see FIG. 1) is connected to the outlet 15b so that the internal passage communicates with the rear chamber 21.

  The position where the inlet 15a and the outlet 15b are formed, that is, the position where the outside air introduction duct 14 and the intake passage 16 are connected is not limited to this embodiment. For example, the inlet 15 a and the outlet 15 b may be formed on the upper surface 15 i of the air cleaner case 15.

  However, the outlet 15b is provided at the upper portion of the air cleaner case 15, specifically, near the upper surface 15i or the upper surface 15i of the peripheral side surfaces 15f, 15g, and 15h in order to prevent a large amount of water from entering the cylinder 3. It is desirable to be formed. Further, the inlet 15a is preferably formed at the upper portion of the air cleaner case 15 so as to correspond to the outlet 15b so as not to increase air flow loss in the air cleaner case 15.

  Further, a return port 15c, which is an opening through which air heated by the compressor 12a flows, is formed in the side surface 15g on the upstream side of the air cleaner case 15. A return passage 19 is connected to the return port 15 c so that the internal passage communicates with the front chamber 20.

  Here, the position where the return port 15 c is formed, that is, the position where the return passage 19 is connected is preferably the lower part of the air cleaner case 15. The lower portion of the air cleaner case 15 is the bottom surface 15j side or the bottom surface 15j of the peripheral side surfaces 15e, 15g, 15h of the air cleaner case 15. More specifically, the bottom surface 15j side or the bottom surface 15j of the peripheral side surfaces 15e, 15g, and 15h is a plane or a curved surface constituting the air cleaner case 15, and is more than half the height of the internal space of the air cleaner case 15. Is also a part located below.

  Thus, by forming the return port 15c in the lower part of the air cleaner case 15, the air pressurized by the compressor 12a and the temperature rising can be introduced into the lower part of the front chamber 20. As a result, snow accumulated in the vicinity of the bottom surface 15j of the front chamber 20 can be efficiently melted, and moisture can be prevented from freezing and the discharge holes 15d being blocked.

  In the above configuration, the air (outside air) flowing through the outside air introduction duct 14 passes through the inlet 15 a and flows into the front chamber 20 of the air cleaner case 15. Air (return warm air) flowing through the return passage 19 flows into the lower portion of the front chamber 20 through the return port 15c. Then, the outside air flowing in from the inlet 15 a and the warm air flowing in from the return port 15 c merge inside the front chamber 20 and pass through the air cleaner 11. The air that has passed through the air cleaner 11 passes through the rear chamber 21 and flows from the outlet 15 b to the intake passage 16.

  In the present embodiment, the air cleaner 11 is erected substantially vertically. However, the arrangement of the air cleaner 11 is not limited to this. For example, you may employ | adopt the structure which arrange | positions the air cleaner 11 horizontally. Even in this case, if the return passage 19 is connected to the upstream side of the air cleaner 11, the air cleaner 11 can be prevented from being blocked by snow due to warm air return.

  Next, with reference to FIG. 3, the warm air return control of the intake device 10 will be described in detail. FIG. 3 is a flowchart showing warm-up return control by the electronic control unit 40 (see FIG. 1).

  As shown in FIG. 3, the electronic control unit 40 reads the temperature T of the outside air detected by the temperature sensor 45 (see FIG. 1) and compares it with a predetermined reference temperature T0 (step S1).

  In step S1, when the outside air temperature T is lower than the reference temperature T0 (YES in step S1), the electronic control unit 40 opens the control valve 48 (see FIG. 1) (step S2). Thereby, a part of warm air after compression flows into the front chamber 20 (see FIG. 1) of the air cleaner case 15 (see FIG. 1) through the return passage 19 (see FIG. 1).

  Next, the electronic control unit 40 performs adjustments such as increasing the combustion injection amount, and controls the operation of the diesel engine 1 so that the operation condition is suitable for performing warm-up return (step S3). Then, the electronic control unit 40 returns the operation from step S5 to S0, and repeats this control.

  On the other hand, when the detected outside air temperature T is higher than the reference temperature T0 in Step S1 (NO in Step S1), the electronic control unit 40 closes the control valve 48 and performs normal engine operation control (Step S1). S4). Then, the electronic control unit 40 returns the operation from step S5 to S0, and repeats this control.

  By performing the above-described control, normally, an efficient operation without returning warm air is performed, and the control valve 48 is opened only when necessary to prevent the air cleaner 11 (see FIG. 1) from being blocked by snow. be able to. In particular, in this embodiment, outside air having a lower temperature than the inside of the engine compartment can be taken in normal operation while preventing the air cleaner 11 from being blocked by snow, so that the output and efficiency of the engine can be improved. Can do.

  The reference temperature T0 is set in consideration of the possibility of the air cleaner 11 being blocked by snow, and is 0 ° C., for example. In consideration of the fact that snow with small snowflakes, such as powder snow seen in low outside air, is easily sucked into the intake path, the reference temperature is set to a temperature lower than 0 ° C., for example, about −10 ° C. May be. Thereby, useless warm-up return can be reduced and the efficiency of the engine can be improved.

  In the above control example, the control valve 48 is operated by the drive signal from the electronic control unit 40. However, for simplicity, the control valve 48 is opened and closed by using a thermostat or the like. 48 may be opened and closed.

  In the above description, an example in which the opening and closing of the control valve 48 is controlled based on the outside air temperature T detected by the temperature sensor 45 has been described. Instead, the interior of the front chamber 20 detected by the snow sensor 46 is shown. The control valve 48 may be controlled based on a signal indicating the presence or absence of snow. Further, the warm air return control may be performed based on the intake pressure value after passing through the air cleaner 11 detected by the pressure sensor 47.

  Further, the control valve 48 may be opened when any of the input values detected by the temperature sensor 45, the snow sensor 46, or the pressure sensor 47 satisfies a predetermined condition.

  Furthermore, warm-up return control may be performed by combining driving information such as the accelerator operation amount and the traveling speed. For example, warm-up return may be performed only when the vehicle is traveling at or below a predetermined reference speed. Such control can suppress a decrease in engine efficiency.

  Next, with reference to FIG. 4, the modification of the warm air return control by the electronic control apparatus 40 (refer FIG. 1) is demonstrated. FIG. 4 is a flowchart showing a modification of the control method.

  As shown in FIG. 4, when all of the input values detected by the temperature sensor 45 (see FIG. 1), the snow sensor 46 (see FIG. 1) and the pressure sensor 47 (see FIG. 1) satisfy a predetermined condition. You may control to open the control valve 48 (refer FIG. 1).

  Specifically, the outside air temperature T detected by the temperature sensor 45 is lower than the reference temperature T0 (YES in step S11), and the suction pressure P detected by the pressure sensor 47 is lower than the reference pressure P0 (YES in step S12). When the presence of snow is detected by the snow sensor 46 (YES in step S13), the electronic control unit 40 opens the control valve 48 (step S14).

  Then, the electronic control unit 40 performs adjustment such as increasing the fuel injection amount in order to obtain an operation state suitable for warm-up return (step S15). Thereafter, the electronic control unit 40 returns the operation from step S17 to step S0, and repeats these controls.

  On the other hand, if any of the conditions is not satisfied in steps S11 to S13 (NO in any of steps S11 to S13), the electronic control unit 40 closes the control valve 48 and performs normal engine operation control ( Step S16). Then, the electronic control unit 40 returns the operation from step S17 to step S0, and repeats this control.

  In this way, by performing control combining the input values detected by the temperature sensor 45, the snow sensor 46, or the pressure sensor 47, unnecessary warm-up return can be reduced, and warm-up return can be performed only when necessary. become.

  For example, even when the outside air temperature T is lower than the reference temperature T0, it is not necessary to return the warm air if snow does not enter the air cleaner case 15 (see FIG. 2). According to this control example, in such a case, unnecessary warm-up return is not performed, so that the overall operating efficiency of the engine can be further improved.

  Next, the temperature rise of the intake air by the compressor 12a (see FIG. 1) of the turbocharger 12 (see FIG. 1) will be described with reference to FIG. FIG. 5 is a graph showing the results of a running test at an outside air temperature of −20 ° C. performed on a vehicle equipped with a turbocharged diesel engine.

  In FIG. 5, the vehicle speed V (km / h) is indicated by a broken line, and the numerical value is indicated on the left vertical axis Y1. The horizontal axis X indicates the elapsed time (sec). Further, the pre-air cleaner temperature T1 indicated by the alternate long and short dash line is the temperature of the air taken into the intake path, and the numerical value is represented on the right vertical axis Y2. In the present embodiment, the pre-air cleaner temperature T1 corresponds to the temperature T1 of the air flowing from the air intake port 14a and flowing through the outside air introduction duct 14 as indicated by the same symbol in FIG. As is clear from FIG. 5, the air temperature T1 before the air cleaner during traveling is approximately equal to the outside air temperature and is about −20 ° C.

  Further, in FIG. 5, the intercooler inlet temperature T2 indicated by a solid line indicates the temperature of the air after being compressed by the compressor 12a (see FIG. 1) of the turbocharger 12 (see FIG. 1). Can be read from the right vertical axis Y2. In the present embodiment, the intercooler inlet temperature T2 corresponds to the temperature T2 of the air that is compressed by the compressor 12a and flows through the intake passage 17, as indicated by the same symbol in FIG. As FIG. 5 shows, it turns out that the temperature T2 of the air after pressurizing with the compressor 12a is about 5-35 degreeC, and is sufficiently higher than external temperature.

  As described above, even if the temperature is low, the air pressurized by the compressor 12a is heated by the compression. Therefore, the air cleaner uses a part of the air whose temperature has been increased by returning to the warm air. Snowflake adhering to 11 can be melted.

  As mentioned above, although the diesel engine 1 provided with the intake device 10 was demonstrated as an example about the intake device which concerns on this invention, the intake device of this invention is not limited and used for a diesel engine. For example, the intake device of the present invention can be used for a gasoline engine.

  Further, in the above-described embodiment, the case of performing outdoor intake is described, but the intake device according to the present invention is also applicable to a vehicle that takes in air from the engine compartment and performs so-called internal intake. .

  The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Diesel engine 2 Engine main body 3 Cylinder 10 Intake device 11 Air cleaner 12 Turbocharger 12a Compressor 13 Intercooler 14 Outside air introduction duct 14a Air intake 15 Air cleaner cases 16, 17, 18 Intake passage 19 Return passage 40 Electronic control unit 45 Temperature sensor 46 Snow sensor 47 Pressure sensor 48 Control valve

Claims (5)

An intake device for an internal combustion engine having an intake passage for taking in air and supplying it to a combustion chamber,
An air intake for taking the air into the intake path;
An air cleaner that allows the air taken in from the air intake to pass through;
A supercharger that compresses the air that has passed through the air cleaner;
A return passage for flowing a part of the air compressed by the supercharger to the upstream side of the air cleaner ,
It said return passage, an intake system for an internal combustion engine, characterized in Rukoto is connected to the lower portion of the air cleaner case for housing the air cleaner.   The intake device for an internal combustion engine according to claim 1, wherein a control valve for controlling a flow of air in the return passage is provided in the return passage. Detecting means for detecting the state of the air taken into the intake passage or the air flowing through the intake passage;
The intake device for an internal combustion engine according to claim 2, further comprising a control unit that controls the control valve based on a detection value of the detection unit.   The said detection means is a temperature detector, and the said control means opens the said control valve, when the temperature detected by the said temperature detector is lower than predetermined value, The said control valve is characterized by the above-mentioned. Intake device for internal combustion engine. An intake air cooler for cooling the air compressed by the supercharger,
The intake device for an internal combustion engine according to any one of claims 1 to 4, wherein the return passage is connected to a downstream side of the supercharger and an upstream side of the intake air cooler.

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