JP2014013020A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine capable of sufficiently suppressing the deposition of oil mist on a passage surface of a diffuser passage.SOLUTION: PCV gas includes: oil mist such that oil in a crank case is changed into mist, and soot derived from carbon based fuel. Most of the oil mist exists in the PCV gas in the state of incorporating the soot therein. A modulation current is carried into a coil 32 so that the oil mist can be charged with electric charges having the same polarity as a passage surface of a diffuser passage 30. As a result, electrostatic repulsion is caused between the oil mist when distributed in the diffuser passage 30, and the passage surface thereof, to suppress the contact of the oil mist with the passage surface.

Description

  The present invention relates to an internal combustion engine. More specifically, the present invention relates to an internal combustion engine having a PCV (Positive Crankcase Ventilation) gas recirculation mechanism.

  Conventionally, in an internal combustion engine that introduces PCV gas from the upstream side of the compressor, the oil mist in the PCV gas adheres to the surface of the diffuser passage of the compressor and solidifies, resulting in a problem that the compressor efficiency decreases. is there. As a solution to this problem, for example, Patent Document 1 discloses a compressor in which a passage surface of a diffuser passage is coated with an oil-repellent fluororesin. According to this compressor, the oil repellent function of the fluororesin can suppress the adhesion of oil mist to the passage surface.

JP 2004-044452 A JP 2010-196537 A Japanese Patent Laid-Open No. 2000-282891 JP 2009-002305 A

  However, in the compressor of Patent Document 1, the oil mist can still contact the surface of the diffuser passage. As long as the oil mist can be contacted, the possibility of adhering to the surface of the passage remains. Therefore, it can be said that further improvement is necessary in order to further suppress adhesion.

  The present invention has been made in view of the above-described problems. That is, an object of the present invention is to provide an internal combustion engine that can sufficiently suppress oil mist from adhering to the surface of the diffuser passage.

In order to achieve the above object, a first invention is an internal combustion engine,
Gas introduction means for introducing blow-by gas containing oil mist into the intake pipe of the internal combustion engine;
A compressor provided with a diffuser passage provided on the downstream side of the gas introduction means connecting portion of the intake pipe and charged on the passage surface;
Oil charging means for charging the oil mist before flowing into the diffuser passage with a charge having the same polarity as the charge polarity of the passage surface;
It is characterized by providing.

The second invention is the first invention, wherein
The oil charging means includes a coil wound around a downstream side of the PCV pipe connection portion of the intake pipe and an upstream side of the compressor installation portion.

The third invention is the first or second invention, wherein
The compressor includes an electrode for charging the surface of the passage.

  According to the present invention, electric charges can be charged on the surface of the diffuser passage of the compressor, and electric charges having the same polarity as the charged polarity of the passage surface can be charged on the oil mist before flowing into the diffuser passage. Therefore, the passage surface and the oil mist can be electrostatically repelled. Therefore, the contact and adhesion of the oil mist to the passage surface can be sufficiently suppressed.

It is a figure which shows typically the system configuration | structure of embodiment. It is a cross-sectional enlarged view of the compressor 12b vicinity of FIG. It is a figure for demonstrating the gas flow inside the compressor 12b.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3.
FIG. 1 is a diagram schematically showing a system configuration of the present embodiment. As shown in FIG. 1, the system of this embodiment includes an engine 10. Each cylinder of the engine 10 is provided with a piston, an intake valve, an exhaust valve, a fuel injector, and the like. Note that the number of cylinders and the cylinder arrangement of the engine 10 are not particularly limited.

  Further, the system of the present embodiment includes a supercharger 12. The supercharger 12 includes a turbine 12 a provided in the exhaust pipe 14 and a compressor 12 b provided in the intake pipe 16. The turbine 12a and the compressor 12b are connected to each other. When the supercharger 12 is operated, the turbine 12a rotates by receiving the exhaust pressure, thereby driving the compressor 12b and compressing the gas flowing into the compressor 12b. The intake pipe 16 is provided with an intercooler 18 for cooling the compressed gas.

  In addition, the system of the present embodiment includes a PCV reflux mechanism that refluxes PCV gas. The PCV gas is a gas (also referred to as blow-by gas) that flows into a crankcase (not shown) from the gap between the piston of the engine 10 and the cylinder wall surface. The PCV gas recirculation mechanism includes a PCV pipe 20. The PCV pipe 20 connects the intake pipe 16 upstream of the compressor 12b and a cylinder head cover (not shown) of the engine 10. The PCV gas is reintroduced into the engine 10 by flowing through the PCV pipe 20 and the intake pipe 16 in this order.

  Next, features of the present embodiment will be described with reference to FIGS. FIG. 2 is an enlarged cross-sectional view of the vicinity of the compressor 12b of FIG. As shown in FIG. 2, the compressor 12 b includes a compressor housing 22 and a compressor plate 24. In the compressor housing 22, an intake passage 26 that communicates with the intake pipe 16, a spiral scroll passage 28 disposed on the outer periphery of an impeller (not shown), and a diffuser passage 30 that communicates the intake passage 26 and the scroll passage 28. And are provided.

  As shown in FIG. 2, a coil 32 is provided in the intake pipe 16 on the upstream side of the compressor housing 22. The coil 32 is wound around the outer periphery of the intake pipe 16 and is connected to a converter (not shown) that can generate a modulated weak current. Since a magnetic field can be generated by operating the converter and supplying a modulation current to the coil 32, a charge is given to the gas (intake gas or PCV gas) passing through the inside of the intake pipe 16 provided with the coil 32. Can do. An electrode 34 is embedded in the surface of the diffuser passage 30. The electrode 34 constitutes a part of a charger (not shown). When the charger is operated, a charge having the same polarity as the charged gas can be charged on the surface of the passage.

  FIG. 3 is a view for explaining the gas flow inside the compressor 12b. In addition, the arrow shown in the figure has shown the flow of intake gas or PCV gas. As described above, by supplying a modulation current to the coil 32, the intake gas or the PCV gas can be charged with the same polarity as the surface of the passage (plus charge in the figure). Therefore, these charged gases flow through the diffuser passage 30 while continuing to receive electrostatic repulsion from the surface of the passage. Accordingly, the charged gas that has flowed through the intake passage 26 reaches the scroll passage 28 side while electrostatically repelling the surface passage of the diffuser passage 30.

  Here, the PCV gas contains oil mist in which the oil in the crankcase is mist and soot derived from carbon-based fuel. Further, most of the oil mist is present in the PCV gas in a state where the soot is taken into the inside thereof. For this reason, if PCV gas is introduced into the intake pipe 16, the soot-containing oil mist increases in temperature as it is compressed in the compressor 12b, and the oil component in the soot is lost by evaporation to reduce the particle size. This phenomenon is particularly prominent when the compressor outlet temperature is 160 ° C. or higher, and when soot-containing oil mist having a reduced particle size adheres to the passage surface, it changes to deposit with a high probability.

  In this regard, according to the present embodiment, the soot-containing oil mist can be charged in the same manner as the PCV gas, so that it can be electrostatically repelled from the surface of the passage when it flows through the diffuser passage 30. Therefore, contact of the soot-containing oil mist with the passage surface can be suppressed. Therefore, it is possible to satisfactorily suppress the occurrence of deposits on the passage surface due to the contact of the soot-containing oil mist, and to prevent a decrease in compressor efficiency due to the deposits.

  In the above-described embodiment, a charge is applied to the intake gas or PCV gas by flowing a modulation current through the coil 32. However, the following modifications are possible with respect to the charge application. First, the installation location of the coil 32 may not be the intake pipe 16 immediately upstream of the compressor 12b. For example, it may be a connection location between the intake pipe 16 and the PCV pipe 20, or may be the PCV pipe 20. That is, as long as the soot-containing oil before flowing into the diffuser passage 30 can be charged, the installation location of the coil 32 can be modified. Second, the charge imparting to the intake gas and the PCV gas may be performed using a charging means other than the coil 32, for example, another known charging device capable of adding a charge using contact charging or frictional charging.

DESCRIPTION OF SYMBOLS 10 Engine 12 Supercharger 12a Turbine 12b Compressor 16 Intake pipe 20 PCV pipe 22 Compressor housing 24 Compressor plate 26 Intake passage 28 Scroll passage 30 Diffuser passage 32 Coil 34 Electrode

Claims (3)

Gas introduction means for introducing blow-by gas containing oil mist into the intake pipe of the internal combustion engine;
A compressor provided with a diffuser passage provided on the downstream side of the gas introduction means connecting portion of the intake pipe and charged on the passage surface;
Oil charging means for charging the oil mist before flowing into the diffuser passage with a charge having the same polarity as the charge polarity of the passage surface;
An internal combustion engine comprising:   2. The internal combustion engine according to claim 1, wherein the oil charging unit includes a coil wound around a downstream side of a PCV pipe connection portion of the intake pipe and an upstream side of a compressor installation portion.   The internal combustion engine according to claim 1, wherein the compressor includes an electrode for charging an electric charge on the passage surface.

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