JP2011236845A - Blow-by gas treatment device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blow-by gas treatment device of an internal combustion engine having a structure which can secure the back-flow of a blow-by gas to an intake passage even in a supercharge region.SOLUTION: In an executer installation unit 60, an executer 62 is arranged in the intake passage 20. A contour of the executer 62 is smaller than the inside diameter of the upstream 20a of the intake passage. The executer 62 includes a low-pressure generation unit 62a. The executer 62 includes a so-called divergent nozzle, and can make the low-pressure generation unit 62a generate low pressure by injecting intake air (intake air flow 100) flowing in the intake passage 20 from the divergent nozzle as a drive gas. The executer 62 has a gas introduction passage 63 for connecting a gas passage 50 and the low-pressure generation unit 62a. The blow-by gas 102 is introduced via the gas introduction passage 63.

Description

  The present invention relates to a blow-by gas processing apparatus for an internal combustion engine.

  Conventionally, for example, as disclosed in Japanese Patent Application Laid-Open No. 62-52211, there is a configuration in which a blow-by gas processing device having a configuration for flowing blow-by gas using an ejector is provided in an internal combustion engine with a supercharger. Are known. In the configuration according to the publication, the end of the gas passage for blow-by gas extending from the rocker cover is communicated with the ejector.

  In the above configuration, the ejector sucks the blow-by gas using the negative pressure generated by the negative pressure generator. The sucked-by blow-by gas is injected into the exhaust passage from a nozzle pipe provided in the exhaust passage of the internal combustion engine. Thus, according to the configuration according to the above publication, blow-by gas can flow into the exhaust passage using the negative pressure of the ejector.

  The prior art according to the above publication has a configuration in which blow-by gas is recirculated to an intake passage (upstream of a surge tank or a compressor) and a configuration in which blow-by gas is caused to flow into an exhaust passage using an ejector under specific conditions. In this configuration, in the supercharging region, the flow of blow-by gas to the upstream of the compressor is basically used, and the blow-by gas recirculation to the upstream of the compressor does not proceed smoothly and the ejector is used under specific conditions that cause the crankcase internal pressure to rise. Thus, blow-by gas flows into the exhaust passage.

JP-A-62-52211 JP 2009-133292 A

  In an internal combustion engine that does not use a supercharger, the intake pressure in the intake passage is lower than the atmospheric pressure in most situations under normal use conditions of the engine. This differential pressure can be used for crankcase ventilation. Specifically, fresh air can flow into the crankcase from the relationship of atmospheric pressure> crankcase internal pressure, and blowby gas flows from the crankcase to the intake passage from the relationship of crankcase internal pressure> intake passage internal pressure. Can do.

  On the other hand, in an internal combustion engine with a supercharger, the above relationship is not established in a supercharging region (an operating state where the compressor downstream of the intake passage is at a pressure higher than atmospheric pressure). Therefore, some measure for treating blow-by gas is required. In this regard, in the conventional technology disclosed in the above publication, the blow-by gas is basically flowed upstream of the compressor in the supercharging region. Under specific conditions where the negative pressure upstream of the compressor is not sufficient, the ejector is used to enter the exhaust passage. Blow-by gas is allowed to flow.

  On the other hand, there is a case where it is desired to ensure as much as possible a state where the blow-by gas is returned to the intake passage even in the supercharging region. In such a case, some configuration for forcibly flowing blow-by gas from the crankcase to the intake passage is required. Specifically, an electric pump or the like is conceivable from the viewpoint of sufficient driving force for flowing blow-by gas, but in practice, a complicated mechanism such as an electric pump is disadvantageous from the viewpoint of cost and the like. There is still room for improvement in the conventional technology regarding the configuration for ensuring that the blow-by gas is returned to the intake passage in the supercharging region.

  The present invention has been made to solve the above-described problems, and provides a blow-by gas processing apparatus for an internal combustion engine having a configuration capable of ensuring that the blow-by gas is returned to the intake passage even in the supercharging region. For the purpose.

In order to achieve the above object, a first invention is a blow-by gas processing apparatus for an internal combustion engine,
A gas passage communicating with a portion where blow-by gas accumulates in an internal combustion engine equipped with a supercharger;
An ejector that is disposed upstream of the compressor of the supercharger inside the intake passage of the internal combustion engine and guides blow-by gas into the intake passage of the internal combustion engine through the gas passage;
It is characterized by providing.

According to a second invention, in the first invention,
An air cleaner provided upstream of the compressor in the intake passage;
The gas passage communicates with a crankcase of the internal combustion engine;
The ejector is
A gas inlet facing the air cleaner side;
A gas outlet facing the compressor,
A low pressure generating portion that is provided between the gas inlet and the gas outlet and generates a low pressure;
A gas introduction path having one end connected to the low pressure generator and the other end connected to the gas passage;
It is characterized by providing.

According to the third invention, in the second invention,
A throttle valve interposed between the ejector and the gas passage is provided.

According to a fourth invention, in the third invention,
The throttle valve is
A valve body for changing an opening degree of a flow path of blow-by gas connecting between the ejector and the gas passage;
Opening degree changing means for changing the opening degree of the valve body in accordance with the pressure difference between the pressure of the low pressure generating portion of the ejector and the atmospheric pressure;
It is characterized by including.

  According to the first aspect of the present invention, the blow-by gas introducing ejector can be disposed at a portion where the pressure is lowered during supercharging in the intake passage. If an ejector is arranged at the part, a low pressure that can contribute to introduction of blow-by gas can be generated with a small ejector effect.

  According to the second aspect of the invention, the low pressure portion generated in the ejector and the crankcase can be connected via the gas passage. By connecting to the low pressure portion generated by the ejector, the crankcase internal pressure can be made lower than the atmospheric pressure.

  According to the third invention, when the crankcase internal pressure is linked to the pressure of the low pressure generating portion of the ejector, the communication state between the crankcase and the low pressure generating portion of the ejector can be adjusted.

  According to the fourth invention, when the crankcase internal pressure is linked to the pressure of the low pressure generating portion of the ejector, the low pressure generation of the crankcase and the ejector is generated according to the difference between the pressure of the low pressure generating portion and the atmospheric pressure. The communication state between the parts can be changed.

It is a figure which shows the structure of the blowby gas processing apparatus of the internal combustion engine concerning embodiment of this invention. It is a figure for demonstrating the structure of the ejector installation part concerning embodiment of this invention. It is a figure for demonstrating the structure of the ejector installation part and throttle valve concerning embodiment of this invention. It is a figure for demonstrating the relationship between the throttle valve flow-path area and pressure in the throttle valve concerning this embodiment. It is a figure for demonstrating operation | movement of the throttle valve in the blowby gas processing apparatus concerning embodiment of this invention. It is a figure for demonstrating operation | movement of the throttle valve in the blowby gas processing apparatus concerning embodiment of this invention.

Embodiment.
(Overall configuration)
FIG. 1 is a diagram showing a configuration of a blow-by gas processing apparatus for an internal combustion engine according to an embodiment of the present invention. The blow-by gas processing apparatus according to the embodiment is suitably used for a vehicle internal combustion engine. The blow-by gas processing apparatus according to the embodiment is applied to the internal combustion engine 10. The internal combustion engine 10 includes a head cover, a cylinder head, a cylinder block, a crankcase, and an oil pan. Inside, a piston and a crankshaft are provided. The internal combustion engine 10 is a supercharged internal combustion engine. In this embodiment, the turbocharger 40 is used as a supercharger. The internal combustion engine 10 is not particularly limited in the number of cylinders and the system thereof, and may be a multi-cylinder internal combustion engine that is common in an internal combustion engine for automobiles.

  An intake passage 20 made of an intake manifold or the like communicates with an intake port of a cylinder head in the internal combustion engine 10. The intake passage 20 communicates with the intercooler 24. A throttle valve 22 is provided between them. The upstream of the intercooler 24 communicates with the intake passage upstream portion 20 a via the compressor 42 of the turbocharger 40. The intake passage upstream portion 20 a is connected to the air cleaner 26 via the ejector installation portion 60. The internal combustion engine 10 is provided with a check valve 12 for a ventilation passage.

  As shown in FIG. 1, an exhaust passage 30 communicates with the exhaust port of the internal combustion engine 10. A turbine 44 of the turbocharger 40 is provided in the exhaust passage 30, and a catalyst 32 is provided further downstream thereof.

  In FIG. 1, the flow of blow-by gas is indicated by a broken-line arrow 102, and the flow of fresh air (intake air) is indicated by a solid-line arrow 100. Hereinafter, in explaining the flow of blow-by gas and fresh air, for convenience, they are also referred to as blow-by gas 102 and intake air 100 (or fresh air 100).

  A gas passage 50 for leading blow-by gas is connected to the crankcase of the internal combustion engine 10. The gas passage 50 is connected to the intake passage upstream portion 20 a via the ejector installation portion 60. Although not shown, the internal combustion engine 10 is provided with a PCV valve or the like as a PCV (positive crankcase ventilation) mechanism.

  The internal combustion engine according to the embodiment is controlled by an ECU (Electronic Control Unit) (not shown). Although not shown, in the embodiment, the internal combustion engine 10 is provided with a configuration for detecting the intake air amount such as an air flow meter, and various sensors such as a crank angle sensor and an engine water temperature sensor. The ECU is connected to various sensors (not shown) to detect the operating state of the engine (engine speed, load, etc.), or is connected to an actuator of various devices for operating the internal combustion engine 10 to operate them. Or The ECU processes signals from each sensor provided in the internal combustion engine 10 and reflects the processing result in the operation of each actuator.

(Configuration of ejector installation)
An ejector installation portion 60 is provided at the joining position of the gas passage 50 and the intake passage upstream portion 20a. As will be described below, the ejector installation portion 60 can flow blow-by gas from the crankcase of the internal combustion engine 10 to the intake passage upstream portion 20a by the ejector 62 provided therein.

  2 and 3 are diagrams for explaining the configuration of the ejector installation unit 60 according to the embodiment of the present invention. 2 and 3 are cross-sectional views of the configuration around the ejector installation portion 60 in the intake passage 20 cut along the intake passage flow direction.

  FIG. 2 is a diagram schematically showing the periphery of the ejector installation portion 60 of the intake passage 20 in the embodiment of the present invention. As shown in FIG. 2, in the ejector installation portion 60, an ejector 62 is provided inside the intake passage 20. The outer shape of the ejector 62 is smaller than the inner diameter of the intake passage 20. The ejector 62 includes a low pressure generator 62a. The ejector 62 includes a so-called divergent nozzle, and can cause the low-pressure generating unit 62a to generate a low pressure by injecting the intake air (intake air flow 100) flowing through the intake passage 20 from the divergent nozzle as a driving gas. An opening (also referred to as “driving gas inlet” for convenience) through which intake air as driving gas flows is provided on the air cleaner 26 side (right side of the drawing) of the ejector 62 with the low pressure generating portion 62a in FIG. . 2 is provided with a divergent nozzle opening (also referred to as a “driving gas discharge port” for the sake of convenience) on the compressor 42 side (the left side of the drawing) of the ejector 62 with the low pressure generation unit 62a interposed therebetween. .

  The ejector 62 includes a gas introduction path 63 for connecting the gas passage 50 and the low pressure generating portion 62a. The blow-by gas 102 is introduced through the gas introduction path 63.

  According to the present embodiment, the blow-by gas introducing ejector 62 can be disposed at a portion where the pressure is lowest in the intake passage 20 during supercharging. If the ejector 62 is disposed at the portion, a low pressure sufficiently low with respect to the atmospheric pressure and the crankcase internal pressure can be generated with a slight ejector effect. Thereby, a sufficiently low pressure that can contribute to the introduction of blow-by gas can be generated.

  The low pressure portion generated in the ejector 62 and the crankcase can be connected via the gas passage 50. By being connected to the low pressure portion generated in the ejector 62, the crankcase internal pressure can be made lower than the atmospheric pressure.

  According to the present embodiment, the pressure loss in the intake passage 20 due to the installation of the ejector 62 can be reduced, and the influence on the engine performance can be reduced. The physique of the ejector 62 can be made small, and the mounting property in the intake passage 20 is also improved. Further, the gas 102 introduced from the crankcase is compressed by the compressor 42 together with the sucked outside air (fresh air) 100 and then flows through the intercooler 24. In this process, gas agitation and cooling are performed, so that adverse effects on combustion due to intake of a mixed gas of blow-by gas and fresh air can be reduced.

(Structure of throttle valve)
FIG. 3 is a diagram more specifically showing the configuration of the ejector installation unit 60 and the configuration of the throttle valve 64 according to the embodiment of the present invention. As shown in FIG. 3, the throttle valve 64 includes a case 66 in which a space is provided, and a sliding valve body 70 provided in the case 66. The case 66 includes a gas passage 50, an atmosphere communication pipe 67 that communicates with the atmosphere, and a first pipe 68 and a second pipe 76 that communicate with the gas introduction path 63 of the ejector 62. The valve body 70 is provided with a hole 72 that communicates with the gas passage 50 at a predetermined position. The valve body 70 is connected to the inner wall on the left side of FIG.
The second conduit 76 and the atmosphere communication pipe 67 communicate with the case 66 with the valve element 70 interposed therebetween, and the valve element 70 is connected to the case 66 in the case 66 in accordance with the relationship between the magnitude of P0 and the magnitude of P1. It is arranged at any position on the left and right sides of the paper.
By positioning the valve body 70 at a position where the hole 72 and the gas passage 50 partially or entirely overlap, a gas flow from the crankcase is introduced into the ejector 62 as indicated by a dotted line in FIG.

FIG. 4 is a diagram for explaining the relationship between the throttle valve channel area and the pressure in the throttle valve 64 according to the present embodiment. In FIG. 4, P ₀ indicates atmospheric pressure, and P ₁ indicates the pressure of the low pressure generating portion 62a. Assuming that the cross-sectional area of the cylindrical portion of the hole 72 is S and the force by which the spring 74 pushes the valve body 70 is F, the balance of the force in the valve body 70 is expressed by the following equation (1).
P ₀ × S = P ₁ × S + F (1)
Since usually P ₀ > P ₁ , the following equation (2) is established.
(P ₀ −P ₁ ) × S = F (2)
The characteristics as to P ₁ is the throttle valve passage area enough decreases squeezed to reduce the flow of gas from the crankcase to the characteristics of the spring (spring constant and the initial tension) and shall be given a cylindrical cross-sectional area S . As shown in FIG. 4, the overlap between the hole 72 and the gas passage 50 is reduced as the pressure difference between P ₀ -P _1, that is, the pressure of the atmospheric pressure and the low pressure generating portion 62 a is increased. .

5 and 6 are diagrams for explaining the operation of the throttle valve 64 in the blow-by gas processing apparatus according to the embodiment of the present invention. FIG. 5 shows a state where the intake air amount is small and P ₀ ≧ P ₁ is satisfied. In this case, the valve body 70 is located slightly on the right side of the paper surface of the case 66 so that the overlap between the hole 72 and the gas passage 50 is maximized. FIG. 6 shows a state when the intake air amount is large and P ₀ >> P ₁ is established. In this case, the valve body 70 is positioned on the left side of the paper in the case 66 in the figure so that the overlap between the hole 72 and the gas passage 50 is very small (almost zero).

  When the ejector 62 is used, an excessively low pressure state may occur depending on the flow velocity of the airflow passing through the ejector 62. This is because, as a principle of the ejector, the degree of pressure decrease is determined according to the velocity of the gas passing through the ejector. At high rotation and high load, a high-speed air flow can be generated, and an excessively low pressure is generated. This causes an unnecessary increase in the force for sucking blow-by gas from the crankcase, resulting in an excessively low crankcase internal pressure. There is a risk that.

In this regard, according to the present embodiment, when the pressure of the low pressure generating portion 62a becomes lower than a certain value with reference to the atmospheric pressure, the throttle valve 64 communicates between the gas passage 50 and the gas introduction passage 63. (That is, communication of the gas flow path from the crankcase to the intake passage) can be blocked. In particular, since it has the characteristics shown in FIG. 4, the gap between the gas passage 50 and the gas introduction passage 63 is increased as the pressure difference between P ₀ -P _1, that is, the pressure of the atmospheric pressure and the pressure of the low pressure generating portion 62 a increases. Can be reduced (see also FIGS. 5 and 6).

  In the embodiment described above, the gas passage 50 is the “gas passage” in the first invention, the turbocharger 40 is the “supercharger” in the first invention, and the internal combustion engine 10 is the above-mentioned In the "internal combustion engine" in the first invention, the intake passage upstream portion 20a is in the "upstream from the compressor of the supercharger in the intake passage of the internal combustion engine" in the first invention. This corresponds to the “ejector” in the first invention.

  In the above-described embodiment, the low pressure generating portion 62a is the “low pressure generating portion” in the second invention, and the gas introducing path 63 is the “gas introducing path” in the second invention. It corresponds. Further, in the above-described embodiment, the throttle valve 64 corresponds to the “throttle valve” in the third invention, and the valve body 70 is connected to the “valve body” in the fourth invention in the case 66 and the atmosphere communication. The pipe 67, the second pipe 76, and the spring 74 correspond to the “opening degree changing means” in the fourth invention.

In the embodiment, the throttle valve 64 that slides the valve body 70 in the case 66 is used. However, the present invention is not limited to such a slide valve. In the present embodiment, by using the throttle valve 64, the “opening degree changing means” in the fourth aspect of the present invention is realized in hardware, but the present invention is not limited to this. A similar function may be realized using software control by using a valve element whose opening degree can be changed by control by the ECU.
In the embodiment, the throttle valve 64 is provided. However, the present invention is not limited to this. Only the configuration in which the blow-by gas is allowed to flow from the gas passage 50 to the intake passage upstream portion 20a using the ejector 62 may be used alone, and the throttle valve 64 is not necessarily provided.

10 Internal combustion engine 12 Ventilation passage check valve 20 Intake passage 20a Intake passage upstream portion 22 Throttle valve 24 Intercooler 26 Air cleaner 30 Exhaust passage 32 Catalyst 40 Turbocharger 42 Compressor 44 Turbine 50 Gas passage 60 Ejector installation portion 62 Ejector 62a Low pressure Generator 63 Gas introduction path 64 Throttle valve 66 Case 67 Atmospheric communication pipe 68 First pipe 70 Valve body 72 Hole 74 Spring 76 Second pipe 100 Intake air (fresh air)
102 blowby gas

Claims (4)

A gas passage communicating with a portion where blow-by gas accumulates in an internal combustion engine equipped with a supercharger;
An ejector that is disposed upstream of the compressor of the supercharger inside the intake passage of the internal combustion engine and guides blow-by gas into the intake passage of the internal combustion engine through the gas passage;
A blow-by gas processing apparatus for an internal combustion engine, comprising: An air cleaner provided upstream of the compressor in the intake passage;
The gas passage communicates with a crankcase of the internal combustion engine;
The ejector is
A gas inlet facing the air cleaner side;
A gas outlet facing the compressor,
A low pressure generating portion that is provided between the gas inlet and the gas outlet and generates a low pressure;
A gas introduction path having one end connected to the low pressure generator and the other end connected to the gas passage;
The blow-by gas processing apparatus for an internal combustion engine according to claim 1.   The blow-by gas processing apparatus for an internal combustion engine according to claim 2, further comprising a throttle valve interposed between the ejector and the gas passage. The throttle valve is
A valve body for changing an opening degree of a flow path of blow-by gas connecting between the ejector and the gas passage;
Opening degree changing means for changing the opening degree of the valve body in accordance with the pressure difference between the pressure of the low pressure generating portion of the ejector and the atmospheric pressure;
The blow-by gas processing apparatus for an internal combustion engine according to claim 3, comprising:

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