1. Field of the Invention
The present invention relates in general to an emission control device of an internal combustion engine, and more particularly to a crankcase emission control device that positively routes blow-by gases from the crankcase to the intake system of the engine. More specifically, the present invention relates to the crankcase emission control devices of a type that positively routes blow-by gases from the crankcase to the intake system through a valve rocker cover chamber of the cylinder head and a gas/liquid separator defined by the cylinder head.
2. Description of the Related Art
Hitherto, various crankcase emission control devices have been proposed and put into practical use in the field of internal combustion engines that are mounted in wheeled motor vehicles. Almost all them are of a type wherein by introducing fresh air into the crankcase, blow-by gases in the crankcase are enforcedly led to the intake system and to the cylinder combustion chambers together with the air-fuel mixture to be burnt. Usually, the crankcase emission control device is equipped at a blow-by gas flowing passage thereof with an oil separator, viz., gas/liquid separator for suppressing migration of a lubrication oil together with the blow-by gases from the crankcase. One of the crankcase emission control devices with such gas/liquid separator is disclosed in Japanese Laid-open Patent Application (Tokkai) 2003-001030. In this disclosed device, the gas/liquid separator is integrally provided on an inner surface of a cylinder head cover that covers an open upper part of the cylinder head.
However, in some of the known crankcase emission control devices including the above-mentioned disclosed device, the gas/liquid separator has been designed without giving a careful consideration to the size of the same, particularly the height of the same. When the height of the separator increases, the height of the cylinder head cover increases and thus in this case, the height of the entire construction of the engine increases, which restricts the freedom to design the engine room hood as well as the freedom to layout the various parts in the engine room.
It is an object of the present invention to provide a crankcase emission control device of an internal combustion engine, which is free of the above-mentioned shortcomings.
According to the present invention, there is provided a crankcase emission control device which has, in a blow-by gas flowing passage, a gas/liquid separator that is integrally formed by a cylinder head at a position just below intake ports of the cylinder head.
In accordance with a first aspect of the present invention, there is provided a crankcase emission control device of an internal combustion engine. The engine has a cylinder head mounted on a crankcase. The cylinder head has a valve rocker cover chamber defined therein and intake and exhaust ports defined therein. The crankcase emission control device comprises a gas/liquid separator integrally formed by the cylinder head at a position below the intake ports, the gas/liquid separator separating an oil mist from blow-by gases flowing therethrough; a first passage defined in both the crankcase and the cylinder head to connect an interior of the crankcase to the valve rocker cover chamber; a second passage that extends from the valve rocker cover chamber to the gas/liquid separator; and a third passage that extends from the gas/liquid separator to an intake system of the engine.
In accordance with a second aspect of the present invention, there is provided a crankcase emission control device for use in an internal combustion engine. The engine includes a cylinder block, an oil pan mounted beneath the cylinder block, a cylinder head mounted on the cylinder block, and a cylinder head cover mounted on the cylinder head to define therebetween a valve rocker cover chamber, the cylinder block and an upper part of the oil pan being combined to constitute a crankcase, the cylinder head having intake and exhaust ports defined therein. The crankcase emission control device comprises a gas/liquid separator integrally formed by the cylinder head at a position below the intake ports for separating an oil mist from blow-by gases flowing therethrough, the gas/liquid separator including a recess that has an open side directed downward and closed by an upper deck surface of the cylinder block; an oil return passage defined in both the cylinder block and the cylinder head to connect an interior of the crankcase and the valve rocker cover chamber; a blow-by gas inlet passage defined in both the cylinder head cover and the cylinder head to connect the valve rocker cover chamber to an interior of the gas/liquid separator; a blow-by gas outlet passage defined in both the cylinder head and the cylinder head cover, the blow-by gas outlet passage having one end exposed to the interior of the gas/liquid separator; and a PCV valve connected to the other end of the blow-by gas outlet passage for controlling a fluid connection between the blow-by gas outlet passage and an intake system of the engine.
In the following, the present invention will be clearly described with reference to the accompanying drawings.
For ease of understanding, various directional terms, such as, right, left, upper, lower, rightward and the like are used in the following description. However, such terms are to be understood with respect to only a drawing or drawings on which a corresponding part or portion is shown.
Referring to the drawings, particularly,
The engine ICE shown is of a three-cylinder in-line type that generally comprises a cylinder block 1, a cylinder head 2 mounted on cylinder block 1, and an oil pan 3 mounted beneath cylinder block 1.
In the illustrated engine ICE, oil pan 3 comprises an upper pan part 3A that is cast from aluminum alloy and a lower pan part 3B that is produced by stamping a steel plate. As shown, lower pan part 3B forms an oil pan proper.
Oil pan 3 and cylinder block 1 are united to constitute a crankcase 5 in which a crankshaft 4 is rotatably installed.
As shown, an upper open end of cylinder head 2 is covered by a cylinder head cover 6 constructed of a plastic. Thus, a hermetically sealed valve rocker cover chamber 10 is defined by cylinder head 2 and cylinder head cover 6, in which cam shafts 7 and 8 for intake and exhaust valves 20 and 21 are operatively installed.
From valve rocker cover chamber 10 to oil pan 3, there extend a plurality of oil return passages 11 that are defined by cylinder head 2 and cylinder block 1. The valve rocker cover chamber 10 is also communicated with the interior of crankcase 5 through a chain chamber (not shown) that is provided at a front end of the engine ICE for housing a timing chain. Accordingly, blow-by gases that get past the piston rings and into crankcase 5 is permitted to flow toward valve rocker cover chamber 10 through the oil return passages 11 and the chain chamber.
Cylinder head 2 is cast from an aluminum alloy and has, as is seen from
Water jacket 18 of cylinder head 2 is communicated with a water jacket 19 of cylinder block 1 through openings of a cylinder head gasket (not shown) that is hermetically put between cylinder block 1 and cylinder head 2. Of course, water jacket 18 of cylinder head 2 and water jacket 19 of cylinder block 1 may be separated to provide independent water jackets respectively.
As is seen from the drawings, intake and exhaust valves 20 and 21 for each cylinder are directly driven by cam shafts 7 and 8 that are positioned above the valves 20 and 21.
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It is to be noted that baffle plates 32 are integral with the cylinder head 2. Due to the one side open construction of rectangular recess 31a with baffle plates 32, such recess 31a is easily formed without using cores (viz., core sand) upon casting of cylinder head 2.
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Although not shown in the drawings, between the mounting surface 2a of cylinder head 2 and a mounting surface of cylinder head cover 6, there is intimately and hermetically put a gasket. Although not shown, the gasket has two extended portions that are formed with circular openings through which the fluid connection between blow-by gas inlet passages 34 and 35 and the fluid connection between blow-by gas outlet passages 36 and 37 are respectively and hermetically achieved.
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In the following, operation of the crankcase emission control device of the present invention will be described with reference to the drawings.
For ease of understanding of the operation, the arrangement of the crankcase emission control device will be briefly reviewed in the following with reference to
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This means that the interior of crankcase 5 is communicated with the downstream area of the throttle valve of engine ICE through valve rocker cover chamber 10, gas/liquid separator 31, flow control valve 38 and their connecting passages 11, 35, 34, 36 and 37.
Under operation of engine ICE, the intake system of engine ICE produces a negative pressure at the downstream area of the throttle valve of engine ICE.
Because of the above-mentioned arrangement of the crankcase emission control device, production of the negative pressure at the intake system of engine ICE causes fresh air to enter the interior of crankcase 5 through fresh air introducing passages (not shown).
The fresh air then picks up blow-by gases in crankcase 5, enters valve rocker cover chamber 10 through oil return passages 11 and the chain chamber and enters gas/liquid separator 31 through the passages 35 and 34. As is seen from
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It is to be noted that since outlet opening 41c of passage 41 is immersed in the lubrication oil in oil pan 3, the negative pressure condition in gas/liquid separator 31 does not introduce blow-by gases into separator 31 from crankcase 5 through passage 41.
Due to occurrence of the negative pressure condition in separator 31, a lubrication oil column is inevitably formed in oil draining passage 41. However, for the reason that has been mentioned hereinabove, the oil column is suppressed from flowing backward into separator 31.
In the following, advantages of crankcase emission control device of the present invention will be described.
First, as is described hereinabove, in the invention, gas/liquid separator 31 is compactly and integrally provided in cylinder head 2 at a position below intake ports 16A, 16B and 16C. In other words, in the invention, the separator 31 is not provided by cylinder head cover 6. Thus, cylinder head cover 6 can be produced with a reduced height. Thus, the entire construction of engine ICE can have a reduced height, which expands the freedom to design the engine room hood as well as the freedom to layout various parts in the engine room.
Second, for the reasons as mentioned hereinabove, gas/liquid separator 31 of the crankcase emission control device can exhibit a very high oil mist separation effect in spite of its simple structure.
Third, separator 31 comprises rectangular recess 31a that is formed in cylinder head 2 with its open side facing downward, and separator 31 is completed by only mounting cylinder head 2 onto cylinder block 1. Due to the one side open structure of rectangular recess 31a, a possible machining to the recess 31a is easily achieved. Furthermore, due to the same reason, the recess 31a can be produced without the aid of cores (viz., core sand) upon casting of cylinder head 2.
Fourth, almost all elements of the crankcase emission control device are integrally provided by major parts of engine ICE, and upon assembly of the major parts, the elements are properly combined to constitute the crankcase emission control device. Thus, reduction in number of parts and reduction in assembling steps are achieved when producing the crankcase emission control device of the present invention.
The entire contents of Japanese Patent Application 2003-102418 filed Apr. 7, 2003 are incorporated herein by reference.
Although the invention has been described above with reference to the embodiment of the invention, the invention is not limited to such embodiment as described above. Various modifications and variations of such embodiment may be carried out by those skilled in the art, in light of the above description.
Number | Date | Country | Kind |
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2003-102418 | Apr 2003 | JP | national |
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4602607 | Balsley | Jul 1986 | A |
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Number | Date | Country |
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2003-001030 | Jan 2003 | JP |
Number | Date | Country | |
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20040244783 A1 | Dec 2004 | US |