JP2006144686A - Ventilation device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To promote evaporation of fuel component mixed in engine oil with a low cost device in a direct injection engine with a supercharger. <P>SOLUTION: This device includes a ventilation air supply pipe 27 connected to an intake system 11 and a chain chamber 10, and a second blow-by gas re-circulation pipe 28 connected to a valve system chamber 8 and the intake system 11. The ventilation air supply pipe 27 is communicated to a common intake pipe 30 between a compressor 13 of the supercharger and an intercooler 14 at an upstream end and is communicated to the chain chamber 10 at a downstream end. A check valve 31 is installed in a middle of the ventilation air supply pipe 27. The second blow-by gas re-circulation pipe 28 is communicated to an oil separation chamber 33 formed in the valve system chamber 8 and is communicated to a common intake pipe 34 between an air cleaner 12 and the compressor 13. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an engine ventilator that can promote the volatilization of fuel components mixed in engine oil, and more particularly to a ventilator for a direct injection engine with a supercharger.

  Conventionally, a blow-by recirculation device (PCV system) that recirculates an unburned air-fuel mixture (unburned gas) that has entered the crank chamber to an intake system of an engine is known.

  Patent document 1 has proposed the PCV system regarding an engine with a supercharger. That is, the PCV system proposed in Patent Document 1 recirculates blow-by gas in the crank chamber to the intake system (downstream of the throttle valve) by intake negative pressure while introducing fresh air into the crank chamber through the valve operating chamber at low load. On the other hand, when the load is high, the blow-by gas in the crank chamber and the valve chamber is directly recirculated to the intake system (upstream from the compressor of the supercharger). Patent Document 1 also discloses that, as a conventional technique, blow-by gas in the crank chamber is recirculated to the intake system (downstream of the throttle valve) by intake negative pressure through the valve operating chamber while introducing fresh air into the crank chamber at a low load. On the other hand, a PCV system that recirculates blow-by gas in the crank chamber and the valve chamber directly to the intake system at the time of high load is illustrated.

  By the way, a so-called direct injection engine that directly injects fuel into a cylinder can increase the compression ratio and improve the combustion efficiency, and therefore tends to be employed in many vehicles. A direct injection engine generally employs a side injector system in which a fuel injection nozzle is inclined and disposed below and adjacent to an intake port. In an engine employing this side injector system, a part of the fresh air flowing into the cylinder from the intake port proceeds downward along the wall surface of the cylinder, and the downward flow of fresh air causes the fuel injection nozzle to A part of the discharged fuel tends to adhere to the wall surface of the cylinder. The fuel adhering to the wall is scraped off by the piston together with the engine oil and enters the crank chamber, and the fuel component in the crank chamber reduces the oil component ratio of the engine oil in the crank chamber. It is easy to cause the problem of deteriorating the lubrication performance.

  In Patent Document 2, in a direct injection engine, when sub-injection in which fuel is injected before and after main injection is performed in addition to main injection in which fuel is injected in the vicinity of compression top dead center, It is easy to adhere to the wall surface, which points out the problem that the fuel enters the crank chamber and the oil component ratio of the engine oil decreases, resulting in a decrease in the lubricating performance of the engine oil. With respect to this problem, Patent Document 2 heats engine oil using a heating means such as a heater when performing sub-injection, thereby promoting the vaporization of fuel components mixed in the engine oil, and vaporizing fuel. It has been proposed to recirculate components to the intake system by the PCV system.

Here, in the PCV system disclosed in Patent Document 2, the first pipe connected to the upstream side of the throttle valve is connected to the valve operating chamber, and the second pipe connected to the downstream side of the throttle valve is connected to the PCV. The structure connected with a valve operating chamber via a valve | bulb is employ | adopted. The valve chamber and the crank chamber are communicated by a blow-by gas passage in the cylinder block. In this PCV system, when the load is low, the PCV valve opens, the blow-by gas in the valve operating chamber is recirculated to the intake system by the negative intake pressure through the second conduit, and fresh air is introduced into the valve operating chamber through the first conduit. The On the other hand, when the load is high, blow-by gas is recirculated from the valve operating chamber to the intake system through the first and second pipes.
Japanese Utility Model Publication No. 5-87213 JP 2004-190513 A

  In the case of an engine with a supercharger, the combustion pressure in the cylinder becomes high, which causes a problem of unburned gas blow-through. Therefore, when the supercharger is mounted on the direct injection engine, the above-mentioned problem of the direct injection engine, that is, the fuel adheres to the wall surface in the cylinder, and as a result, the engine oil in the crank chamber is easily diluted with fuel components. The problem of blow-by gas due to supercharging is added to the above problem, and further includes the problem that engine oil in the crankcase is more easily diluted with fuel components. Although the invention described in Patent Document 2 may be applied to this problem, the invention of Patent Document 2 requires special means such as a heater and is an expensive apparatus.

  An object of the present invention relates to a direct-injection engine with a supercharger in which engine oil entering a crank chamber is easily diluted with a fuel component, and an engine capable of promoting the vaporization of the fuel component mixed into the engine oil at a low cost. It is to provide a ventilation device.

In order to achieve the above technical problem, according to the present invention,
An engine ventilation device that recirculates blow-by gas generated in an engine having a fuel injection nozzle disposed facing a combustion chamber of each cylinder and a supercharger disposed in an intake system to the intake system. There,
A blowby gas recirculation passage for recirculating blowby gas inside the engine to the intake system when the supercharger generates a supercharging pressure;
An air supply passage for taking in ventilation air into the engine;
An open / close valve that is interposed in the air supply passage and opens when the supercharger generates supercharging pressure, and opens the air supply passage;
The blow-by gas recirculation passage has an upstream end communicated with the valve operating chamber of the engine, and a downstream end communicated with the upstream side of the turbocharger of the intake system,
The air supply passage has an upstream end communicated with a downstream side of the turbocharger of the intake system, and a downstream end communicated with a crank chamber of the engine. Is done.

  That is, according to the present invention, when supercharging pressure is generated, blow-by gas is recirculated to the intake system while fresh air is introduced into the crank chamber through the air supply passage. Therefore, in the direct injection engine with a supercharger, as described above, unburned gas tends to easily enter the crank chamber, but the crank chamber generates an environment in which fuel is easily vaporized by fresh air introduced through the air supply passage. Therefore, without limiting to the fuel injection mode of the direct injection engine, the volatilization of the unburned gas mixed in the engine oil is promoted, and the engine oil is diluted with the unburned gas and the lubrication performance is improved. It is possible to suppress the decrease. Also, since the on / off valve is opened only when the turbocharger generates supercharging pressure by the on / off valve interposed in the air supply passage, the supercharger does not generate supercharging pressure. The blow-by gas can be prevented from flowing back to the intake system through the air supply passage.

  In a preferred embodiment of the present invention, the engine is covered with a cover member that communicates with the valve chamber disposed in the upper portion, the crank chamber disposed in the lower portion, the valve chamber and the crank chamber. A power transmission chamber having a power transmission chamber containing an endless power transmission member that links a crankshaft in the crank chamber and a valve mechanism in the valve chamber, and an air supply passage is connected to the crank via the power transmission chamber. It communicates with the chamber and communicates with the valve train chamber. In the power transmission chamber, the engine oil is sprayed onto the power transmission member by an oil jet to lubricate the endless power transmission member, so the power transmission chamber is filled with mist-like oil. The mist-like oil containing the fuel component from the crank chamber is prevented from inadvertently entering, reducing the possibility that the lubricating oil film in the meshing part of the timing chain and the sprocket will break the oil film due to the fuel component. Lubricating performance of engine oil sprayed on the transmission member can be stabilized.

  In a preferred embodiment of the present invention, the intake system of the engine has an intercooler downstream of the supercharger, and the upstream end of the air supply passage is connected to the supercharger and the intercooler in the intake system. And communicated with. According to this, since the relatively high temperature fresh air compressed by the supercharger is introduced into the engine through the air supply passage, volatilization of the unburned gas mixed in the engine oil can be further promoted. .

  In a preferred embodiment of the present invention, it further includes an oil separator for separating the oil component from the blow-by gas returning to the intake system through the blow-by gas recirculation passage, and after the oil component is removed by the oil separator The blow-by gas can be recirculated to the intake system. The oil separator may be an oil separation chamber provided in the valve operating chamber, or an oil separation tank interposed in a blow-by gas recirculation passage.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a side view schematically showing a direct injection engine with a supercharger and its intake system. The engine 1 includes, for example, a cylinder block 2 in which four pistons (not shown) are arranged in series, a cylinder head 3 that is disposed above the cylinder block 2 and defines a combustion chamber of each cylinder, and a cylinder head 3, and an oil pan 5 disposed below the cylinder block 2, and engine oil 7 is stored below the crank chamber 6 by the oil pan 5.

  As is known, the cylinder head 3 has an intake port (not shown) and an exhaust port (not shown) that open to face each cylinder, and an intake valve and an exhaust valve operating mechanism for opening and closing the intake port (not shown). (Not shown) is accommodated in a valve operating chamber 8 sealed with a head cover 5. The engine 1 has a chain chamber 10 as a power transmission chamber sealed by a chain cover 9 at one end thereof, and the chain chamber 10 has endless power that links a crankshaft (not shown) and a valve mechanism. A timing chain as a transmission member is provided, and the intake valve and the exhaust valve are driven to open and close at a predetermined timing synchronized with the rotation of the engine 1 by this timing chain.

  The engine 1 has a spark plug disposed facing the top of each combustion chamber, and a fuel injection nozzle disposed at an inclination below and adjacent to the intake port, and each cylinder is defined by the fuel injection nozzle. Fuel is supplied directly to the combustion chamber.

  The intake system 11 of the engine 1 includes, in order from an air cleaner 12 for introducing fresh air at the upstream end thereof, for example, a compressor 13 of a supercharger such as an exhaust supercharger, an intercooler 14, a throttle body 16 containing a throttle valve 15, an intake air Supercharging air is supplied to the intake port of each cylinder through each branch pipe of the intake manifold 17 including the manifold 17.

  Reference numeral 20 in FIG. 1 denotes a PCV valve. The PCV valve 20 is interposed in a first blowby gas recirculation passage 21 that communicates with the crank chamber 6 and the intake manifold 17. A chamber 22 constituting an oil separation chamber is provided. The PCV valve 20 opens when the negative pressure in the intake manifold 17 is larger than the set biasing force of the check valve. For example, when the pressure in the intake manifold 17 is negative at low load, Blow-by gas is returned to the intake manifold 17.

  The engine oil 7 in the oil pan 5 is pumped up by an oil pump (not shown), and the pumped oil is supplied to bearings such as a crankshaft and a camshaft through an oil gallery (not shown), while the oil jet Is used to spray pistons and timing chains. The valve chamber 8 communicates with the crank chamber 6 through an oil return passage 23 formed in the cylinder block 2, and the chain chamber 10 communicates with the crank chamber 6 through the lower opening 24 and moves through the upper opening 25. It communicates with the valve chamber 8. The engine oil supplied to the valve mechanism in the valve chamber 8 returns to the crank chamber 6 through the oil return passage 23, and the engine oil injected toward the timing chain in the chain chamber 10 passes through the lower opening 24. Return to the crank chamber 6.

  The direct injection engine 1 includes a ventilation air supply pipe 27 connected to the intake system 11 and the chain chamber 10, and a second blowby gas recirculation pipe 28 connected to the valve operating chamber 8 and the intake system 11. A ventilation device 29 is provided when supercharging pressure is generated. More specifically, the ventilation air supply pipe 27 has an upstream end communicated with a common intake pipe 30 between the compressor 13 and the intercooler 14 of the supercharger, and a downstream end communicated with the chain chamber 10. ing. A check valve 31 is interposed in the ventilation air supply pipe 27. The check valve 31 allows a flow from the intake system 11 to the chain chamber 10 and prohibits a reverse flow.

  As a modification, an on-off valve may be used instead of the check valve 31, and the on-off valve is preferably a solenoid valve that can be opened and closed by a signal. When a solenoid valve is provided in the ventilation air supply pipe 27, it is only necessary to control the opening and closing of the solenoid valve so that the solenoid valve is closed in an operating state in which the engine 1 side flows backward to the intake system 11. Thereby, blow-by gas in the crank chamber 6 can be prevented from inadvertently flowing back to the intake system 11. As a modification of the ventilation air supply pipe 27, the upstream end of the ventilation air supply pipe 27 communicates with a common intake pipe 32 between the intercooler 14 and the throttle body 16, as indicated by a virtual line in FIG. 1. Also good.

  The second blow-by gas recirculation pipe 28 has an upstream end communicated with an oil separation chamber 33 formed in the valve operating chamber 8, and a downstream end connected to a common intake pipe 34 between the air cleaner 12 and the compressor 13. It is communicated. The oil separation chamber 33 in the valve operating chamber 8 has a role of a separator that separates the oil component contained in the blow-by gas, and can thereby separate the oil from the gas component returning to the intake system 11. The second blow-by gas recirculation pipe 28 functions to supply ventilation air when blow-by gas is recirculated to the intake system 11 via the first blow-by gas recirculation passage or the recirculation pipe 21 at a low load. This contributes to simplification of the piping system. As a modification, an independent oil separator such as an oil separation tank may be provided in the second blow-by gas recirculation pipe 28 instead of or in addition to the oil separation chamber 33.

  According to the above embodiment, when the intake negative pressure downstream of the throttle valve 15 is higher than a predetermined value, for example, when the load is low, the blow-by gas in the crank chamber 6 is supplied to the first blow-by gas recirculation pipe or recirculation by the intake negative pressure. The air is returned to the intake manifold 17 through the passage 21. On the other hand, fresh air for ventilation is supplied from the valve operating chamber 8 through the first blow-by gas reflux pipe or the reflux passage 21.

  Further, when the compressor 13 of the supercharger is generating a supercharging pressure, in other words, when the pressure inside the engine 1 is lower than the pressure of the intake system 11 downstream of the compressor 30, the intake system 11 is used for ventilation. The fresh air enters the chain chamber 10 through the ventilation air supply pipe 27, enters the crank chamber 6 through the lower opening 24 of the chain chamber 10, and enters the valve operating chamber 8 through the upper opening 25. The blow-by gas in the crank chamber 6 is recirculated to the intake manifold 17 through the first blow-by gas recirculation pipe 21 and enters the valve operating chamber 8 through the oil return passage 23 in the cylinder block 2. The gas component after the oil component is separated in the oil separation chamber 33 is returned to the common intake pipe 34 upstream of the compressor 13 through the second blow-by gas reflux pipe 28. Therefore, in the direct-injection engine 1 with a supercharger in which the fuel component easily enters the crank chamber 6, the crank chamber 6 and the valve chamber 8 are actively ventilated with fresh air. The environment is improved so that the fuel volatilization condition at 8 becomes an unsaturated state, and the vaporization of the fuel component mixed in the engine oil can be promoted. Therefore, according to the Example, it can suppress that engine oil is diluted with a fuel component, and can suppress the fall of the lubrication performance of engine oil.

  In the preferred embodiment, an orifice 35 is provided in the ventilation air supply pipe 27 to limit the amount and pressure of ventilation air introduced from the intake system 11 through the chain chamber 10 into the crank chamber 6 and the valve operating chamber 8. It is preferable to do this.

  Since fresh air for ventilation is supplied to the crank chamber 6 and the like through the chain chamber 10, the inside of the chain chamber 10 is replaced with fresh air, and the fuel component in the crank chamber 6 is included. The oil mist will not inadvertently enter the chain chamber 10, which can stabilize the lubrication performance of the engine oil injected toward the timing chain, and the oil film breakage due to the fuel component of the timing chain rotating at high speed. Problems can be suppressed. Particularly in an engine whose output is increased by supercharging, the oil film breakage of the timing chain causes a problem of promoting wear on the small meshing surface of the chain. It is effective to introduce new air.

  Further, as shown by a solid line in FIG. 1, when the upstream end of the ventilation air supply pipe 27 is connected to the upstream of the intercooler 14, relatively hot fresh air immediately after being compressed by the compressor 13 is used as ventilation air. Since the fuel is supplied to the engine 1, the above-described fuel volatilization can be further promoted.

It is a figure which shows the outline | summary of the ventilation apparatus of the direct injection engine with a supercharger of an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Direct injection engine 5 Oil pan 6 Crank chamber 7 Engine oil 8 Valve train chamber 9 Chain cover 10 Chain chamber 11 Intake system 12 Air cleaner 13 Compressor 14 Intercooler 15 Throttle valve 16 Valve body 17 Intake manifold 20 PCV valve 21 1st blow-by gas Reflux pipe 23 Oil return passage 27 Ventilation air supply pipe 28 Second blow-by gas return pipe

Claims (4)

An engine ventilation device that recirculates blow-by gas generated in an engine having a fuel injection nozzle disposed facing a combustion chamber of each cylinder and a supercharger disposed in an intake system to the intake system. There,
A blowby gas recirculation passage for recirculating blowby gas inside the engine to the intake system when the supercharger generates a supercharging pressure;
An air supply passage for taking in ventilation air into the engine;
An open / close valve that is interposed in the air supply passage and opens when the supercharger generates supercharging pressure, and opens the air supply passage;
The blow-by gas recirculation passage has an upstream end communicated with the valve operating chamber of the engine, and a downstream end communicated with the upstream side of the turbocharger of the intake system,
The ventilating device for an engine, wherein an upstream end of the air supply passage communicates with a downstream side of the supercharger of the intake system, and a downstream end communicates with a crank chamber of the engine. The engine includes a valve train chamber disposed in an upper portion, a crank chamber disposed in a lower portion, a power transmission chamber that is in communication with the valve train chamber and the crank chamber and is covered with a cover member. A power transmission chamber that houses an endless power transmission member that links the crankshaft in the crank chamber and the valve mechanism in the valve chamber;
2. The engine ventilation device according to claim 1, wherein the air supply passage communicates with the crank chamber through the power transmission chamber and also communicates with the valve operating chamber. The engine intake system has an intercooler downstream of the supercharger;
The engine ventilation device according to claim 1 or 2, wherein an upstream end of the air supply passage is communicated between the supercharger and the intercooler in the intake system. The engine ventilation device according to any one of claims 1 to 3, further comprising an oil separator for separating an oil component from blow-by gas returning to the intake system through the blow-by gas return passage.

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