JP6982542B2 - Engine with blow-by gas recirculation device - Google Patents

Description

The present invention relates to an engine with a blow-by gas recirculation device such as an industrial engine and an engine for a traveling vehicle.

The engine has a mechanism that recirculates the blow-by gas that collects in the crankcase to the intake system such as the air intake passage, mixes it with the new air-fuel mixture and burns it, and prevents it from being released to the atmosphere as it is, that is, the blow-by gas recirculation device. It is provided. In an engine with a blow-by gas recirculation device, it is desirable to remove liquid components such as oil (oil mist) and water contained in the blow-by gas as much as possible before returning the engine to the intake passage.

Therefore, conventionally, a configuration is often adopted in which the liquid component is returned to the intake system from the crankcase through the cylinder head and the head cover so that the liquid component can be easily captured inside the engine. As such an example, the one disclosed in Patent Document 1 is known.

Japanese Unexamined Patent Publication No. 2008-163837

Generally, the piping that returns blow-by gas to the intake system is exposed to the outside of the engine, so it tends to be vulnerable to cold weather. Under extremely low temperature conditions, the blow-by gas returning to the intake passage is cooled by the fresh air in the intake passage, and the moisture in the blow-by gas freezes at the outlet of the pipe, which may cause clogging.

An object of the present invention is an engine with a blow-by gas recirculation device configured to guide blow-by gas in a crankcase through the inside of a head cover to an intake system, which is connected to an intake system in a blow-by gas passage by structural ingenuity. It is an object of the present invention to provide an engine with a blow-by gas recirculation device which is made difficult to freeze at the terminal portion thereof and which is improved so as not to cause the above-mentioned inconvenience due to freezing at a low temperature as much as possible.

In the present invention, the intake system that sends air to the intake manifold has a cover intake passage provided across the blow-by gas outlet of the head cover in the intake passage connecting the air cleaner and the turbocharger.
The cover intake passage is attached to the blow-by gas outlet with a gasket in between.
The blow-by gas passage at the blow-by gas outlet and the cover intake passage are communicated with each other through a communication hole provided in the gasket.
The bottom wall of the blow-by gas passage shall be provided with a return hole for dropping trapped oil and a downward slope formed around the return hole in a state where the height decreases toward the return hole. It is characterized by.
For example, there is a configuration in which a blow-by gas outlet portion is formed below the cover intake passage in the head cover, and the return hole and the downward inclined surface are formed on the bottom wall of the blow-by gas outlet portion.

The head cover is a place where heat is conducted from the cylinder head and becomes warm, and blow-by gas is returned to the cover intake passage which is a part of the warm head cover. Therefore, even if the intake air is cold due to extremely cold weather, the temperature of the air flowing through the cover intake passage rises, so that the water in the blow-by gas returned to the middle of the passage is eliminated or suppressed. Become.
In addition, the bottom wall of the blow-by gas passage is provided with a return hole and a downward slope that decreases toward the return hole, so that oil will flow naturally due to gravity even if the engine is slightly tilted. In addition, it has the advantage of facilitating the action of trapped oil being collected in the return hole by the downhill slope.

As a result, an engine with a blow-by gas recirculation device, which has been improved so that the above-mentioned inconvenience due to freezing at low temperature is not caused as much as possible, is made in a state where it is difficult to freeze at the terminal portion connected to the intake system in the blow-by gas passage by devising the structure. Even if the engine is slightly tilted, the oil in the blow-by gas can be provided in a preferable state in which the oil in the blow-by gas is satisfactorily reduced into the engine through the return hole.

Left side view of industrial diesel engine Front view of the engine shown in FIG. Right side view of the engine shown in FIG. Top view of the engine shown in FIG. Rear view of the engine shown in FIG. Top view around the front of the head cover Left side view of a partial notch showing the head cover and cover intake passage Top view of the head cover Bottom view of the head cover Front view of the head cover and a partial notch according to the cross-sectional view taken along the line XX of FIG. (A) Plan view of the gas outlet cover showing the cover intake passage, (B) Bottom view of the gas outlet cover showing the cover intake passage. The relationship between the blow-by gas outlet and the valve gear is shown, (A) is a cross-sectional view, and (B) is a longitudinal sectional view of the main part. (A) Side view of discharge reed valve, (B) Side view of return reed valve (A) Plan view of gasket, (B) Cross-sectional view of gasket and its upper and lower parts Bottom view showing a valve body with a rubber-coated tip

Hereinafter, an embodiment of the engine with a blow-by gas recirculation device according to the present invention will be described with reference to the drawings when applied to an industrial diesel engine.

As shown in FIGS. 1 to 5, in an industrial diesel engine (hereinafter, simply abbreviated as an engine) E, a cylinder head 2 is assembled on the upper part of a cylinder block 1, and a head cover 3 is attached on the upper part of the cylinder head 2. It is assembled, and the oil pan 4 is assembled at the lower part of the cylinder block 1. A transmission case 5 is assembled at the front end of the cylinder block 1, an engine cooling fan 6 is arranged at the front of the transmission case 5, and a flywheel 7 is arranged at the rear of the cylinder block 1. The upper half of the cylinder block 1 is formed in the cylinder 1A, and the lower half is formed in the crankcase 1B.

At the front of the engine E, a drive pulley 8 attached to the shaft end of a crank shaft (not shown), a drive fan pulley 6A of the engine cooling fan 6, and a transmission belt 10 straddling the passive pulley 9A of the dynamo (alternator) 9. A water flange 21 and the like are deployed. The left side of the engine E is equipped with an exhaust manifold 11, a supercharger 12, a starter 13, an oil filter 14, and the like. The right side of the engine E is equipped with an intake manifold 15, a fuel injection pump housing 16, a stop solenoid 17, and the like, and three injectors 18, a compressor upstream suction passage 19, a compressor downstream suction passage 20, and the like are arranged above. There is.

The suction passage 20 on the downstream side of the compressor includes a start end side pipe 20A connected to the compressor housing 12A and arranged across the head cover 3, and a terminal side pipe 20B connecting the start end side pipe 20A and the intake manifold 15. It is composed of. As shown in FIG. 4, the starting end side pipe 20A is arranged along the rear side of the cover intake passage 19A in a plan view. The bent pipe 19B, the starting side pipe 20A, and the ending side pipe 20B may be made of a pipe made of a flexible material such as rubber, or a metal pipe.

As shown in FIGS. 4, 6, 7, and 10, the engine E is configured to guide the blow-by gas in the crankcase 1B through the inside of the head cover 3 to the intake system k. The device A is equipped. The head cover 3 is a bottomless box-shaped (top lid-shaped) component that is assembled to the cylinder head 2 across the valve gear B, and a plurality of ribs 3a extending to the left and right are formed inside the cover. The rear portion of the head cover 3 is provided with a hole 22 for supplying engine oil.

The intake system k has a cover intake passage 19A provided in the blow-by gas outlet portion 3A of the head cover 3, and the blow-by gas passage 26 of the blow-by gas outlet portion 3A and the cover intake passage 19A are communicated with each other. The cover intake passage 19A is configured as a part of a compressor upstream suction passage (an example of the suction passage) 19 connecting the air cleaner 23 (see FIGS. 4 and 6) and the turbocharger 12. That is, the compressor upstream side suction passage 19 includes a cover intake passage 19A and a curved pipe 19B connecting the cover intake passage 19A and the compressor housing 12A of the turbocharger 12. The intake system k is a concept in which the air cleaner 23, the intake manifold 15, and the like are all passages for sending the air a to the combustion chamber (not shown).

Here, the main function (reflux portion to the intake system k) in the blow-by gas recirculation device A will be briefly described. As shown in FIGS. 6 and 7, the blow-by gas g flowing from the cylinder block 1 into the internal space of the head cover 3 passes through the discharge lead valve (an example of the discharge check valve) 31 of the blow-by gas outlet portion 3A. Enter the space 26, which is a blow-by gas passage. The blow-by gas g that has entered the space 26, which is also called a CCV (crankcase ventilation) chamber, is reduced to the cover intake passage 19A, that is, to the intake system k, through the communication hole 38 of the gasket 35.

Next, the head cover 3 and the cover intake passage 19A will be described in detail.
As shown in FIGS. 6 to 10, the head cover 3 having a rounded quadrangle (oval) in a plan view has a blow-by gas outlet portion 3A having an upward open shape formed at the front end portion of the top wall 3C. .. The blow-by gas outlet portion 3A is formed in the head cover 3 as an open box-shaped portion having a space portion 26 surrounded by a vertically facing partition wall 24 and a bottom wall 25 and a joint surface 27 which is an upper surface.

The space portion 26, which is a blow-by gas passage, is a trapezoidal portion having a short side on the right side in a plan view, and the bottom wall 25 is mainly different from the shallow main bottom surface 25A in the front-rear direction. It has sink bottoms 25B and 25B formed on the front and back of the bottom 25A, respectively. A discharge reed valve 31 for sending out blow-by gas g from the inside of the head cover 3 is equipped in a sideways (leftward) posture at the front-rear center portion of the main bottom surface 25A, which has a sideways T-shape in a plan view.

As shown in FIGS. 7 to 10, 12, and 13, the discharge reed valve 31 has a thin-walled discharge valve body 31A arranged on the main bottom surface 25A and a thick-walled discharge valve guide 31B, respectively. It is configured by bolting to the bottom wall 25 on the root side of the. The round tip portion 31a of the discharge valve body 31A is arranged above the discharge valve hole 31C formed in the bottom wall 25 by opening to the main bottom surface 25A, and is usually a lid of the discharge valve hole 31C (valve closed). situation). The portion of the discharge valve hole 31C in the bottom wall 25 is formed in a protruding hole wall 25a that has a circular shape concentric with the discharge valve hole 31C and protrudes downward when viewed in the vertical direction. In the discharge reed valve 31, the main bottom surface 25A has a function of a valve seat 25A that abuts on the tip portion 31a.

The sink bottom surface 25B includes a downhill inclined surface 32 that becomes lower from the front and back to the front or the back of the discharge reed valve 31, and a lowest surface 33 that continues to the lower side of the downhill inclined surface 32 (see FIG. 8). The lowest surface 33 is configured to be located closer to the left side with respect to the downhill inclined surface 32. A return valve hole (an example of a return hole) 33a penetrating vertically is formed on each of the lowest surfaces 33 and 33 of the bottom wall 25, and a return lead valve (an example of a return check valve) 34 for these return valve holes 33a is formed. It is provided.

That is, the bottom wall 25 of the space portion 26 is provided with a return valve hole 33a capable of dropping the oil captured from the blow-by gas g in the space portion 26, and the peripheral portion of the bottom wall 25 around the return valve hole 33a. A downhill inclined surface 32 is formed in which the height decreases toward the return valve hole 33a. Each return valve hole 33a is formed so as to be open to the lowest surface 33 having a height lower than that of the main bottom surface 25A.

As shown in FIGS. 7 to 10, 12, and 13, the return reed valve 34 has a return valve body 34A in contact with the lowermost surface 33 on the bottom wall 25, that is, the lowermost back surface 33A, and a thick return valve body 34A. The valve guide 34B is bolted to the bottom wall 25 on the root side of each. The return reed valve 34 is provided in an upside-down position with the discharge reed valve 31, and normally, the return valve hole 33a is lightly closed by the tip portion 34a of the return valve body 34A, or the return valve body 34A is It is in a very slightly open state due to a slight sagging displacement. The return reed valve 34 has a function of a valve seat 33A in which the minimum back surface 33A abuts on the tip end portion 34a.

Each of the return reed valves 34 and 34 is arranged in a sideways posture in which the tip portion 34a of the return valve body 34A is on the left side, and the return that drops the oil captured from the oil mist or the like contained in the blow-by gas g in the space portion 26. It is a valve that acts on the valve hole 33a. The diameter of each return valve hole 33a is smaller than the diameter of the discharge valve hole 31C. It is convenient if the discharge valve body 31A and the return valve body 34A, and the discharge valve guide 31B and the return valve guide 34B are the same parts, but they may be different. As shown in FIGS. 8 and 9, a pair of return reed valves 34 are provided in the front-rear direction with the discharge reed valve 31 interposed therebetween.

As shown in FIGS. 6 to 8 and 11, a gas outlet cover 3B is bolted onto the blow-by gas outlet portion 3A, and the gas outlet cover 3B includes the lid cover portion 36 and the cover intake passage 19A. It is configured with. The lid cover portion 36 has an outer shell shape similar to that of the blow-by gas outlet portion 3A in a plan view, and is a portion fixed to the head cover 3 by bolting at three locations with the gasket 35 interposed therebetween.

As shown in FIG. 11, the cover intake passage 19A is meandering in which the passage end portion 19b of the cover intake passage 19A is bent outward in the longitudinal direction of the head cover 3 with respect to the passage start end portion 19a of the cover intake passage 19A. It is formed in the passage. Specifically, the cover intake passage 19A extends in a direction orthogonal to (an example of intersection) in the longitudinal direction (front-back direction) of the head cover and is parallel to each other. It has a passage intermediate portion 19c that is diagonally oriented in the front-rear, left-right directions, and is formed in a meandering passage that has a crank shape (substantially Z shape) in a plan view.

The passage intermediate portion 19c is formed in a groove-shaped passage portion having a U-shaped cross section facing downward, and the opening 37 at the lower end thereof is in a state in which the shape in a plan view is similar to that of the groove-shaped passage portion 19c and opens downward. Is formed in. Further, the lid cover portion 36 is formed with a lightening portion 36a that is located behind the opening 37 and opens downward, and bolt holes 3b are formed at three locations. As shown in FIG. 11B, the lower end of the lid cover portion 36 is formed on the joint lower surface 36b having a substantially “sun” shape.

As shown in FIG. 14A, the gasket 35 is a thin plate-like (sheet-like) having one communication hole 38 and three bolt insertion holes 39. As shown in FIG. 14 (B), the gasket 35 is sandwiched between the joint surface 27 which is the upper surface of the blow-by gas outlet portion 3A and the joint lower surface 36b (of the gas outlet cover 3B) of the lid cover portion 36. It is provided in a state. The outer shape of the joint surface 27 of the blow-by gas outlet portion 3A, the outer shape of the gasket 35, and the outer shape of the lid cover portion 36 are the same as each other.

As shown in FIG. 6, the space portion 26 of the blow-by gas outlet portion 3A has an upper surface opening that covers almost the entire surface of the opening port 37 of the lid cover portion 36, and the communication hole 38 of the gasket 35 is a space portion. This is the only place where the 26 and the opening 37 are communicated with each other. That is, the communication hole 38 is set as a hole that determines the communication area between the passage intermediate portion 19c (opening port 37) and the space portion 26 and the communication position with respect to the passage intermediate portion 19c. It can be said that the communication hole 38 determines the communication position with respect to the space portion 26. Although the communication hole 38 is set as a circular hole, various shapes such as an ellipse and a square can be set.

The valve gear B will be briefly described. As shown in FIGS. 8, 10, and 12, the valve gear B includes a rocker arm shaft 28 that is supported by a plurality of shaft support portions 2a erected on the cylinder head 2 and extends in the front-rear direction, and a rocker. It is configured to have a plurality of rocker arms 29, 30 for supply and exhaust swingably supported by the arm shaft 28 (six in total).

The rocker arms 29 and 30 include drive side ends 29a and 30a for operating a supply / discharge valve (not shown) and passive side ends 29b and 30b driven by a push rod (not shown). The cylinder head 2 is formed with a push rod hole (not shown) formed for passing the push rod, and as shown in FIG. 8, blow-by gas g is introduced into the head cover 3 through the push rod hole. Will be sent to.

As shown in FIG. 12B, the valve gear B and the bottom wall 25 are closest to each other on the front rocker arm 29, the second rocker arm 30 from the front, and the back surface of the downward inclined surface 32. It is between the upper and lower sides of a certain inclined back surface 32a. More specifically, as shown in FIG. 12 (A), there is a sufficient clearance between the upper and lower passive side ends 29b and 30b that have moved to the top and the corresponding inclined back surfaces 32a, even at the closest point. That is, it is set so that the clearance c (example: 3 mm) is secured.

In the blow-by gas recirculation device A, the inside of the head cover 3 and the space portion 26 are separated from each other by a discharge reed valve 31 and a bottom wall 25 provided with two return reed valves 34, 34, and the space portion 26 is provided. Is communicated with the cover intake passage 19A by the communication hole 38 of the gasket 35. Therefore, when the internal pressure of the head cover 3 is higher than the pressure of the cover intake passage 19A, the discharge reed valve 31 opens, and the blow-by gas g in the head cover 3 passes through the discharge reed valve 31, the space portion 26, and the communication hole 38. It enters the passage middle portion 19c and is returned to the intake system k.

Then, when the internal pressure of the head cover 3 and the pressure of the cover intake passage 19A are the same, or when the internal pressure of the head cover 3 is lower than the pressure of the cover intake passage 19A, the pair of return lead valves 34, 34 are opened. When the return reed valve 34 is opened, the oil (engine oil) captured from the blow-by gas g in the space 26 is dropped into the head cover 3 (below the bottom wall 25) from the front and rear return valve holes 33a and 33a. Is done. The oil that falls from the return valve hole 33a is not only returned to the inside of the engine, but also a valve operating valve such as a sliding portion (not shown) between the rocker arm shaft 28 and the rocker arm 29, as shown in FIG. 12 (b). A good lubrication function supplied to the device B can also be obtained.

In the engine with a blow-by gas recirculation device according to the present invention, the cover intake passage 19A, which is a part of the intake passage 19 on the upstream side of the compressor, is attached to the head cover 3, and the blow-by gas passage 26 of the blow-by gas outlet portion 3A and the cover intake passage 19A are provided. The intermediate portion 19c of the passage is communicated with the communication hole 38 of the gasket 35. The head cover 3 is a place where heat is conducted from the cylinder head 2 and becomes warm, and the blow-by gas g is returned to the cover intake passage 19A which is a part of the warm head cover 3.

Therefore, even if the intake air a is cold due to extremely cold weather or the like, the temperature of the air a flowing through the cover intake passage 19A rises [see FIG. 11 (A)]. Freezing of water will be eliminated or suppressed. As a result, it becomes difficult to freeze at the terminal portion connected to the intake system of the blow-by gas passage 26, and it is possible to provide an engine with a blow-by gas recirculation device which is improved so as to minimize the inconvenience caused by freezing at a low temperature. ..

Since the downward inclined surface 32 whose height decreases toward the return valve hole 33a is formed in the peripheral portion of the return valve hole 33a, the action of the captured oil to collect in the return valve hole 33a is promoted and the action is promoted. There is an advantage that oil can flow into the return valve hole 33a even if the engine is slightly tilted.
Since the return reed valve 34 for the return valve hole 33a is provided, there is an advantage that the captured oil can be dropped while preventing the blow-by gas g from flowing into the space portion 26 from the return valve hole 33a. ..

Since the valve gear B is arranged below the return valve hole 33a, the oil dropped from the return valve hole 33a supplies lubricating oil to the sliding portion between the rocker arm 29 and the rocker arm shaft 28. There is also an advantage that can be done.
Since the return reed valves 34 and 34 are arranged in the front and rear of the discharge reed valve 31, it is convenient because the oil can smoothly flow into any of the return valve holes 33a regardless of whether the former person leans forward or backward. Is.

[Another Embodiment]
As shown in FIG. 15, a thin film made of rubber (an example of an elastic material) 40 is formed on the surface of the return lead valve 34 at the tip 34a of the return valve body 34A and on the side surface in contact with the valve seat 33A, that is, a rubber sheet. It is convenient if the (rubber film) 40 is coated. There is an advantage that it can contribute to the improvement of the sealing property when the valve seat 33A and the tip portion 34a come into contact with each other. The two places designated by the reference numerals 41 are holes for inserting bolts.

The rubber sheet 40 may be coated on the surface of the discharge lead valve 31 on the side where the tip portion 31a of the discharge valve body 31A is in contact with the valve seat 25A. Further, instead of the tip portions 34a and 31a, the valve seats 33A and 25A may be coated with the rubber sheet 40. The elastic material 40 may be a flexible synthetic resin or the like, in addition to rubber.

The return check valve 34 and the discharge check valve 31 may be configured by a valve having a structure other than the reed valve, such as an umbrella valve. The downhill inclined surface 32 may be a downhill inclined surface to the front or the back, a surface inclined to the left or right, or a surface to be downhill to two or more of the front, back, left, and right.

1B Crankcase 3 Head cover 3A Blow-by gas outlet 12 Supercharger 19 Suction passage 19A Cover intake passage 23 Air cleaner 25 Bottom wall 26 Blow-by gas passage 31 Discharge check valve 32 Downward inclined surface 33A Valve seat 33a Return hole 34 Return check valve 34A Valve body 34a Valve body tip
35 gasket
38 Communication hole 40 Elastic material B Valve gear k Intake system

Claims (6)

An engine with a blow-by gas recirculation device that is configured to guide blow-by gas in the crankcase through the inside of the head cover to the intake system.
The intake system has a cover intake passage provided across the blow-by gas outlet of the head cover in the suction passage connecting the air cleaner and the turbocharger.
The cover intake passage is attached to the blow-by gas outlet portion with a gasket interposed therebetween.
The blow-by gas passage of the blow-by gas outlet portion and the cover intake passage are communicated with each other through a communication hole provided in the gasket .
The bottom wall of the blow-by gas passage is provided with a return hole through which oil trapped in the blow-by gas passage can fall.
An engine with a blow-by gas recirculation device in which a downward inclined surface whose height decreases toward the return hole is formed in a portion of the bottom wall around the return hole.
The engine with a blow-by gas recirculation device according to claim 1 , wherein a return check valve is provided which allows oil to fall from the return hole and prevents backflow from the return hole to the blow-by gas passage side. .. The blow-by gas recirculation device according to claim 2, wherein the check valve is composed of a reed valve, and an elastic material is coated on the valve seat of the reed valve or the tip of the valve body in contact with the valve seat. With engine. The bottom wall is provided with an discharge check valve that allows the inflow of blow-by gas into the blow-by gas outlet and prevents the outflow from the blow-by gas outlet.
The engine with a blow-by gas recirculation device according to claim 2 or 3, wherein a pair of return check valves is provided with the discharge check valve interposed therebetween. The engine with a blow-by gas recirculation device according to any one of claims 1 to 4, wherein a valve gear is arranged below the return hole. The cover intake passage is provided at the blow-by gas outlet portion of the head cover.
The engine with a blow-by gas recirculation device according to any one of claims 1 to 5, wherein the bottom wall is a bottom wall of the blow-by gas outlet portion.

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