JP2005264759A - Blow-by gas recirculation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blow-by gas recirculation device capable of suppressing oil caulking in a supercharger. <P>SOLUTION: This blow-by gas recirculation device recirculates a blow-by gas leaking from the combustion chamber 11a to the crankcase 11b of an engine 11 to an intake passage 12 on the upstream side of the supercharger 14 through a blow-by gas passage 22. A PCV cooler 23 for cooling the blow-by gas is installed in the blow-by gas passage 22. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a blow-by gas recirculation device used in an internal combustion engine equipped with a supercharger.

  In an engine mounted on a vehicle, blow-by gas (unburned mixture or combustion gas) leaks from the combustion chamber into the crank chamber through a gap between the piston and the wall surface of the cylinder. Blow-by gas can cause engine oil to deteriorate and rust inside the engine. Further, the unburned gas of blow-by gas cannot be released to the atmosphere because it contains a large amount of hydrocarbons (HC). Therefore, the blow-by gas leaked into the crank chamber is generally returned to the intake passage by a blow-by gas recirculation device (PCV: positive crankcase ventilation) and recombusted.

  In an engine with a supercharger, when the blowby gas is recirculated to the intake passage downstream of the supercharger, the pressure in the intake passage on the downstream side of the supercharger rises when the supercharger is activated. It becomes difficult to return to the intake passage. Therefore, a blow-by gas recirculation device configured to recirculate blow-by gas to the intake passage on the upstream side of the supercharger has been proposed (see, for example, Patent Document 1).

FIG. 3 shows a schematic configuration of the blow-by gas recirculation device of Patent Document 1.
In this blow-by gas recirculation device, a part of the intake air cooled by the intercooler 42 downstream of the supercharger 41 is introduced into the ventilation case 44 in the head cover 43, so that a mist (mist) contained in the blow-by gas is obtained. Oil) is cooled. Thereby, mist-like (mist-like) oil is liquefied and oil is efficiently recovered in the ventilation case 44.

In this blowby gas recirculation device, blowby gas leaking from the combustion chamber 46a of the engine 46 to the crank chamber 46b is introduced into the ventilation case 44 through the gas passage 46c inside the engine body. The blow-by gas hits a baffle plate (not shown) provided in the ventilation case 44, and after mist-like (mist-like) oil contained in the blow-by gas is dropped to some extent, the blow-by gas passes through the blow-by gas passage 47. Then, the refrigerant is returned to the intake passage 49 on the upstream side of the compressor 48. The blow-by gas merges with the intake air sucked from the air cleaner 50 and is supplied together with the intake air from the intake manifold 51 into the combustion chamber 46a via the intercooler 42, and then from a fuel injection valve (not shown). It is mixed with the injected fuel and burned.
Japanese Patent Laid-Open No. 6-221939 (FIG. 1)

  By the way, in the blow-by gas recirculation device that recirculates the blow-by gas to the intake passage 49 upstream of the supercharger 41 as described above, when the supercharger 41 is in a high supercharge state, the oil is supplied in the compressor 48. Problems such as caulking (carbonization) occur. That is, when the supercharger 41 is in a high supercharging state, the blow-by gas that has become high temperature in the engine 46 is compressed by the compressor 48 together with the intake air, and becomes further hot. Therefore, the oil contained in the blow-by gas is caulked (carbonized) near the outlet of the compressor 48, which becomes an intake resistance and causes a reduction in supercharging efficiency.

  This invention is made | formed in view of such a situation, The objective is to provide the blow-by gas recirculation apparatus which can suppress the oil coking in a supercharger.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
The invention according to claim 1 is a blow-by gas recirculation device that recirculates the blow-by gas leaked from the combustion chamber of the internal combustion engine to the crank chamber to the intake passage on the upstream side of the supercharger through the blow-by gas passage, wherein the blow-by gas passage And a cooling means for cooling the blow-by gas.

  According to this configuration, since the high-temperature blow-by gas heated in the internal combustion engine is cooled by the cooling means and then returned to the intake passage on the upstream side of the supercharger, the intake air introduced into the supercharger Temperature rise can be suppressed. Therefore, even when the supercharger is in a highly supercharged state and the blowby gas is compressed by the compressor, the problem that the oil in the blowby gas cokes near the outlet of the supercharger can be avoided.

  According to a second aspect of the present invention, in the blow-by gas recirculation apparatus according to the first aspect, a branch between a first passage in which the cooling means is provided in the blow-by gas passage and a second passage for bypassing the cooling means. And a control means for controlling the switching valve based on the operating state of the internal combustion engine to switch the flow path of the blowby gas to one of the first passage and the second passage. The summary is provided.

  According to this configuration, when the switching valve is controlled based on the operating state of the internal combustion engine and the flow path of the blow-by gas is switched to the first passage side, the blow-by gas is cooled by the cooling means. Oil coking can be suppressed. Moreover, when the flow path of blow-by gas is switched to the 2nd channel | path side, overcooling of blow-by gas can be prevented by bypassing a cooling means.

  According to a third aspect of the present invention, in the blow-by gas recirculation apparatus according to the second aspect, the internal combustion engine has a temperature for directly or indirectly detecting the temperature of the intake air flowing in the vicinity of the compressor of the supercharger. The gist of the invention is that a detecting means is provided, and the control means controls the switching valve so that the blow-by gas flows into the first passage when the temperature by the temperature detecting means is higher than a predetermined temperature.

According to this configuration, the high-temperature blow-by gas warmed by the internal combustion engine can be reliably cooled by the cooling means.
According to a fourth aspect of the present invention, there is provided the blowby gas recirculation apparatus according to the third aspect, wherein the temperature detecting means comprises a water temperature sensor for detecting a temperature of cooling water of the internal combustion engine.

According to this configuration, the temperature of the intake air can be indirectly detected based on the temperature of the cooling water detected by the water temperature sensor.
The invention according to claim 5 is the blow-by gas recirculation device according to claim 2, wherein the control means controls the switching valve based on an operating state of the supercharger.

  The degree to which the blow-by gas is compressed by the compressor together with the intake air and rises in temperature varies depending on the operating state (supercharging state) of the supercharger. Therefore, by focusing on this point and controlling the switching valve based on the operating state of the supercharger, it becomes possible to appropriately switch the flow path of the blow-by gas and thereby bring the blow-by gas to an appropriate temperature. .

  According to a sixth aspect of the present invention, in the blow-by gas recirculation device according to the fifth aspect, the blow-by gas flows into the first passage only when the supercharger is operating in a high supercharging state. The gist is to control the switching valve.

  According to this configuration, when the supercharger is operating in a high supercharging state, the blowby gas flow path is switched to the first passage side to cool the blowby gas by the cooling means, and the supercharger is low supercharged. When it is operating or stopped in the state, it is possible to prevent the blowby gas from being overcooled by switching the flow path of the blowby gas to the second passage side.

  A seventh aspect of the present invention is the blowby gas recirculation apparatus according to the first aspect, further comprising control means for controlling the cooling capacity of the cooling means based on the operating state of the internal combustion engine.

  According to this configuration, since the blow-by gas can be appropriately cooled based on the operating state of the internal combustion engine, oil coking in the supercharger and oil supercooling in the cooling means can be suppressed.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a schematic configuration of a supercharged engine mounted on a vehicle and a blow-by gas recirculation device thereof.

In the intake passage 12 of the engine 11, an air cleaner 13, a supercharger 14, and an air-cooled intercooler 15 are provided in that order from the upstream side.
The supercharger 14 includes a turbine wheel 16 and a compressor wheel 17 and supercharges intake air introduced into the combustion chamber 11a of the engine 11 using exhaust pressure. Specifically, the turbine wheel 16 is provided on the upstream side of the catalytic converter (not shown) in the exhaust passage 18, and the compressor wheel 17 is provided on the downstream side of the air cleaner 13 in the intake passage 12. The intercooler 15 is provided on the downstream side of the compressor wheel 17 in the intake passage 12.

  During operation of the engine 11, when exhaust is blown to the turbine wheel 16 in the supercharger 14 and the turbine wheel 16 rotates, the compressor wheel 17 rotates accordingly, and the intake air drawn from the air cleaner 13 is compressed. And enter intercooler 15. The intake air is cooled by the intercooler 15 and its volume is compressed, and then supplied to the combustion chamber 11 a of the engine 11.

  The blow-by gas recirculation device according to the present embodiment includes a ventilation case 21a provided in the head cover 21 of the engine 11 and a blow-by gas passage 22 that recirculates the blow-by gas in the case 21a to the intake system.

  The blow-by gas passage 22 includes a first passage 22a and a second passage 22b. One end of the first passage is connected to the head cover 21 of the engine 11, and the other end is connected to the upstream side of the supercharger 14 in the intake passage 12. In the engine 11, blow-by gas leaking from the combustion chamber 11a to the crank chamber 11b is introduced into the ventilation case 21a through a gas passage (not shown) inside the engine body. The ventilation case 21a is provided with a baffle plate (not shown), and mist-like oil contained in the blow-by gas adheres to the baffle plate and is separated from the blow-by gas. The blow-by gas from which the oil has been separated flows out from the ventilation case 21a into the first passage 22a.

  A PCV cooler 23 is provided in the middle of the first passage 22a. The PCV cooler 23 is an air-cooled cooler similar to the intercooler 15 of the supercharger 14 and is provided in the vicinity of the intercooler 15 in the engine room of the vehicle. In FIG. 1, for convenience, the PCV cooler 23 is illustrated at a location away from the intercooler 15. The PCV cooler 23 cools the blow-by gas flowing through the first passage 22a by exchanging heat with the cooling air that is ventilated when the vehicle travels.

  In the blow-by gas passage 22, the second passage 22 b connects the upstream side and the downstream side of the PCV cooler 23 so as to bypass the PCV cooler 23. A three-way valve 24 is provided at a connection portion on the upstream side of the second passage 22b with respect to the first passage 22a.

  The three-way valve 24 is an electromagnetic switching valve that is controlled based on the output signal of the electronic control device 25, and bypasses the blow-by gas passage in the blow-by gas passage 22 with the first passage 22 a provided with the PCV cooler 23. It switches to any one of the 2nd channel | path 22b which is a channel | path.

  The engine 11 is provided with various sensors for detecting the operating state. For example, a supercharging pressure sensor 31 for detecting the pressure (supercharging pressure) of the intake air downstream of the intercooler 15, a crank angle sensor 32 for detecting the engine speed, and an accelerator depression amount An accelerator sensor 33, a water temperature sensor 34 for detecting the temperature of the cooling water of the engine 11, and the like are provided.

  Detection signals of the various sensors 31 to 34 are taken into the electronic control device 25. The electronic control unit 25 performs overall control of the engine 11 and includes a control program and a memory that stores data necessary for executing the program.

  The electronic control unit 25 calculates command values for the fuel injection amount and the fuel injection timing based on the accelerator depression amount obtained from the detection signal of the accelerator sensor 33, the engine rotational speed obtained from the detection signal of the crank angle sensor 32, and the like. . Then, by driving a fuel injection valve (not shown) based on these command values, the fuel injection amount and the fuel injection timing are controlled so that the thermal efficiency, the exhaust emission, and the like are improved.

  Further, the electronic control unit 25 controls the three-way valve 24 based on the engine water temperature obtained from the detection signal of the water temperature sensor 34 to switch the blow-by gas flow path in the blow-by gas passage 22.

  Next, a specific processing procedure for switching the flow path of the blow-by gas in the blow-by gas recirculation apparatus of the present embodiment will be described with reference to the flowchart of FIG. 2 is executed at predetermined time intervals by the electronic control device 25.

  First, the electronic control unit 25 takes in the detection signal of the water temperature sensor 34, calculates the engine water temperature based on the detection signal (step S100), and determines whether the engine water temperature is equal to or higher than a predetermined temperature (for example, 0 ° C.). (Step S110). The predetermined temperature is set so as to prevent overcooling of the oil contained in the blow-by gas, and is appropriately changed according to the characteristics of the engine oil used.

  If it is determined in step S110 that the engine water temperature is equal to or higher than the predetermined temperature, the electronic control unit 25 controls the three-way valve 24 to switch the blow-by gas flow path to the first passage 22a side where the PCV cooler 23 is provided (step). S120). In this case, the hot blow-by gas warmed in the engine 11 is cooled by the PCV cooler 23 and then returned to the intake passage 12 on the upstream side of the supercharger 14. Therefore, the temperature rise of the intake air introduced into the supercharger 14 is suppressed.

  On the other hand, if it is determined in step S110 that the engine water temperature is lower than the predetermined temperature, the electronic control unit 25 controls the three-way valve 24 to switch the blow-by gas flow path to the second passage 22b side (step S130). In this case, the low-temperature blow-by gas flows through the second passage 22 b, bypasses the PCV cooler 23, and is returned to the intake passage 12.

Further, the electronic control unit 25 ends the series of control processes after the process of step S120 or S130.
As described above, according to the present embodiment, the following effects can be obtained.

  (1) Since the high-temperature blow-by gas warmed in the engine 11 is cooled by the PCV cooler 23 and then returned to the intake passage 12, it is possible to suppress the temperature rise of the intake air introduced into the supercharger 14. it can. Therefore, when the supercharger 14 is in a high supercharging state, the intake air compressed by the supercharger 14 is prevented from reaching a temperature at which oil coking occurs (for example, 160 ° C.). Therefore, the problem that the oil contained in the blow-by gas cokes near the outlet of the supercharger 14 is solved, and a decrease in supercharging efficiency can be prevented. Further, by cooling the high-temperature blow-by gas with the PCV cooler 23, the intake air becomes low temperature and its density increases, so that the intake air charging efficiency can be increased and the output torque of the engine 11 can be improved. It becomes.

  (2) When the engine water temperature detected using the water temperature sensor 34 is equal to or higher than the predetermined temperature, the flow path of the blow-by gas is switched to the first passage 22a side, and the blow-by gas is cooled by the PCV cooler 23. On the other hand, when the engine water temperature is lower than the predetermined temperature, the flow path of the blow-by gas is switched to the second passage 22b side, and the PCV cooler 23 is bypassed. In this way, the high-temperature blow-by gas warmed inside the engine can be reliably cooled by the PCV cooler 23. Further, when the blow-by gas is at a low temperature, overcooling of the oil in the blow-by gas can be prevented, and clogging of the blow-by gas passage caused by the adhesion of the oil can be avoided.

  (3) The PCV cooler 23 is an air-cooled cooler like the intercooler 15 and is provided in the vicinity of the intercooler 15 in the engine room. For this reason, in the intercooler 15 and the PCV cooler 23, a part of the passage of the cooling air taken from the outside of the vehicle can be used in common, which is practically preferable.

The above embodiment may be implemented by changing to the following modes.
In the above embodiment, the electronic control unit 25 detects the engine water temperature and controls the three-way valve 24 based on the engine water temperature, but in addition to this, the supercharging pressure, the engine speed, the accelerator The three-way valve 24 may be controlled based on the engine operating state such as the depression amount. For example, the electronic control unit 25 determines the operating state of the supercharger 14 based on the engine operating state such as the supercharging pressure, the engine speed, and the accelerator depression amount, and sets the three-way valve 24 according to the operating state. Control. Here, when the electronic control unit 25 determines that the supercharger 14 is operating in a high supercharging state, the electronic control unit 25 switches the blow-by gas flow path to the first passage 22a side, and blows off the blow-by gas by the PCV cooler 23. When it is cooled and it is determined that the supercharger 14 is operating or stopped in a low supercharging state, the flow path of the blow-by gas is switched to the second passage 22b side. Even in this case, oil coking in the supercharger 14 can be suppressed.

  A temperature sensor that detects the discharge temperature may be provided in the supercharger 14 or in the vicinity of the outlet of the supercharger 14, and the three-way valve 24 may be controlled according to the discharge temperature of the supercharger 14. In this case, the electronic control unit 25 controls the three-way valve 24 so as to cool the blow-by gas in a region where there is a risk of coking according to the discharge temperature of the supercharger 14 (a region where the discharge temperature exceeds a predetermined temperature). To do.

  In the above embodiment, the PCV cooler 23 is an air-cooled cooler, but is not limited to this. As the PCV cooler 23, a cooler capable of adjusting the cooling capacity may be used. In this case, the blow-by gas can be appropriately cooled by controlling the cooling capacity of the cooler based on the operating state of the engine 11. Therefore, oil coking in the supercharger 14 and oil supercooling in the PCV cooler 23 can be suppressed. Further, when the cooling capacity of the PCV cooler is controlled, the three-way valve 24 and the second passage 22b can be omitted.

  In the above embodiment, the three-way valve 24 is controlled by the engine control electronic control device 25 that controls the fuel injection amount and the fuel injection timing. However, the present invention is not limited to this. For example, a control device for controlling the three-way valve 24 may be provided separately from the electronic control device 25 for engine control. However, as in the above-described embodiment, the configuration in which the three-way valve 24 is controlled by the electronic control device 25 can reduce the number of parts, which is advantageous in terms of cost.

The schematic block diagram which shows the engine with a supercharger of one embodiment, and its blow-by gas recirculation apparatus. The flowchart for demonstrating the switching process of a three-way valve. The schematic block diagram which shows the engine with a conventional supercharger, and its blowby gas recirculation apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine as an internal combustion engine, 11a ... Combustion chamber, 11b ... Crank chamber, 12 ... Intake passage, 14 ... Supercharger, 22 ... Blow-by gas passage, 22a ... First passage, 22b ... Second passage, 23 ... Cooling PCV cooler as means, 24 ... three-way valve as electromagnetic switching valve, 25 ... electronic control device as control means, 34 ... water temperature sensor as temperature detection means.

Claims (7)

A blow-by gas recirculation device for recirculating blow-by gas leaked from a combustion chamber of an internal combustion engine to a crank chamber through a blow-by gas passage to an intake passage on the upstream side of the supercharger,
A blow-by gas recirculation apparatus comprising cooling means provided in the middle of the blow-by gas passage for cooling the blow-by gas. A switching valve provided at a branch portion between a first passage in which the cooling means is provided in the blow-by gas passage and a second passage for bypassing the cooling means;
The control means for controlling the switching valve based on the operating state of the internal combustion engine to switch the flow path of the blow-by gas to one of the first passage and the second passage. The blowby gas reflux device according to 1. The internal combustion engine is provided with temperature detection means for directly or indirectly detecting the temperature of intake air flowing in the vicinity of the compressor of the supercharger,
The blow-by gas according to claim 2, wherein the control means controls the switching valve so that the blow-by gas flows into the first passage when the temperature by the temperature detection means is higher than a predetermined temperature. Reflux apparatus. The blow-by gas recirculation device according to claim 3, wherein the temperature detection means includes a water temperature sensor that detects a temperature of cooling water of the internal combustion engine. The blow-by gas recirculation device according to claim 2, wherein the control means controls the switching valve based on an operating state of the supercharger. The said control means controls the said switching valve so that blow-by gas flows into the said 1st channel | path only when the said supercharger is operate | moving in the high supercharging state. Blow-by gas recirculation device. The blow-by gas recirculation device according to claim 1, further comprising a control unit that controls a cooling capacity of the cooling unit based on an operating state of the internal combustion engine.

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