JP2021120548A - Engine with blow-by gas recirculation device - Google Patents

Abstract

To provide an engine with an improved blow-by gas recirculation device which makes a gas passage in a head cover less likely to be frozen and minimizes occurrence of closure by freezing and growth of ice blocks at a lower temperature while having a structure that causes a blow-by gas to pass through the head cover and then return it to an intake passage.SOLUTION: An intake passage has a cover intake passage part 19A which is provided at a head cover 3 in such a manner that the cover intake passage part 19A communicates with a cover internal gas passage. An inflow hole 31C, which allows a blow-by gas to flow into the cover internal gas passage 26, is formed at a bottom wall 25 which separates a space portion 3h, excluding the cover internal gas passage 26, of the head cover 3 from the cover internal gas passage 26. A thickness of a peripheral edge part 25a forming the inflow hole 31C at the bottom wall 25 is set so as to be smaller than a diameter of the inflow hole 31C.SELECTED DRAWING: Figure 3

Description

The present invention relates to an engine with a blow-by gas recirculation device, such as an industrial engine mounted on a tractor or a construction machine, or an engine for a traveling vehicle.

The engine is equipped with a mechanism that recirculates the blow-by gas that collects in the crankcase to the intake passage such as the intake manifold, mixes it with a new air-fuel mixture and burns it, and prevents it from being released to the atmosphere as it is, that is, a blow-by gas recirculation device. Has been done. 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 passage 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. 2008-1638337

In general, the return passages such as the piping for returning the blow-by gas to the intake passage and the head cover are exposed to the outside instead of the inside of the engine, and therefore tend to be easily cooled. In cryogenic conditions, blow-by gas flows through the extremely cold head covers and pipes to cool them, and the water in the blow-by gas freezes inside the head covers and pipes, which can cause clogging.

An object of the present invention is to adopt a configuration in which blow-by gas in the crankcase is returned to the intake passage after passing through the inside of the head cover, but by devising a structure, the gas passage in the cover in the head cover is hard to freeze, and at low temperature. It is an object of the present invention to provide an engine with a blow-by gas recirculation device which is improved so as not to cause the above-mentioned inconvenience due to freezing.

The present invention relates to an engine with a blow-by gas recirculation device configured to guide blow-by gas in a crankcase through a gas passage in the cover provided inside the head cover and then to an intake passage.
The intake passage has a cover intake passage portion provided on the head cover in a state of communicating with the gas passage in the cover.
An inflow hole that allows blow-by gas to flow into the gas passage in the cover is formed in the partition wall that separates the space portion other than the gas passage in the cover and the gas passage in the cover inside the head cover.
The partition wall is characterized in that the thickness of the peripheral edge portion forming the inflow hole is set to be smaller than the diameter of the inflow hole.

Regarding the present invention, refer to claims 2 to 6 for feature configurations and means other than the above-mentioned configurations (means).

The head cover becomes warm due to heat conduction from the cylinder head when the engine is rotating, but when the engine is stopped, it is also the first place where the engine body including the cylinder block and the cylinder head starts to cool. Therefore, the blow-by gas flowing in the head cover is also cooled and the water content is frozen, which may cause the gas passage in the cover to be clogged.

In the present invention, the location where the blow-by gas is returned in the intake passage is set in the cover intake passage portion provided as a part of the head cover that becomes warm due to heat conduction from the cylinder head. Therefore, when the engine is rotating, even if the intake air is cold due to extremely cold weather, the temperature of the air flowing through the cover intake passage rises, and the water in the blow-by gas returned to the cover intake passage is frozen. It will be suppressed.

Also, when the engine is started, the head cover is cold, so the water in the blow-by gas may cool and freeze even in the gas passage inside the cover. It is easy to freeze because it is accelerated. Therefore, since the thickness of the peripheral edge portion forming the inflow hole is made thin so as to be smaller than the diameter of the inflow hole, the length of the easily cooled portion becomes short and it becomes difficult to freeze. In addition, since the freezing length is shortened, even if an ice block is formed in the inflow hole, it is easily blown off by an increase in the internal pressure of the engine, and the effect of eliminating the possibility that the freezing grows and the inflow hole is blocked can be expected.

As a result, while adopting a configuration in which the blow-by gas is returned to the intake passage after passing through the inside of the head cover, the moisture in the blow-by gas is prevented from being frozen at the return point to the intake passage and the gas passage in the cover, so that the blow-by gas is frozen at a low temperature. It is possible to provide an engine with a blow-by gas recirculation device that is improved so that the blow-by gas passage is not clogged due to freezing or freezing as much as possible.

Front view of industrial diesel engine Top view of the engine shown in FIG. Left side view showing a head cover with a cover intake passage Top view of the head cover with cover intake passage Bottom view of the head cover with cover intake passage (A) Plan view of blow-by gas outlet, (B) Bottom view of cover intake passage (A) Front view of the cover intake passage portion, (B) is a sectional view taken along line ZZ of (A). The main part of the gas passage in the cover is shown, (A) vertical sectional view, (B) horizontal sectional view. (A) Top gasket, (B) Intermediate gas case, (C) Bottom gasket (A) Enlarged side view showing the structure of the inflow reed valve, (B) Enlarged side view showing the structure of the return reed valve. An exploded perspective view showing the structure of the head cover and the cover intake passage.

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 and 2, in the industrial diesel engine (hereinafter, simply abbreviated as engine) E, the cylinder head 2 is assembled on the upper part of the cylinder block 1, and the head cover 3 is attached on the upper part of the cylinder head 2. Assembled, the oil pan 4 is assembled to 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 of a cylinder (notation omitted), and the lower half of the cylinder block 1 is formed of a crankcase 1B.

At the front of the engine E, a drive pulley 8 attached to the shaft end of a crankshaft (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 (not shown), 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 compressor upstream side suction passage 19 includes a cover intake passage portion 19A and a curved pipe 19B connecting the cover intake passage portion 19A and the compressor housing 12A of the supercharger 12. 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. 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. 1 and 2 and FIGS. 3 to 5, 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 passage k. The device A is equipped. The head cover 3 is a substantially bottomless box-shaped (top lid-shaped) part that is assembled to the cylinder head 2 across a valve gear (not shown), and includes a cover body 3H, a gas outlet cover 3B, an intermediate gas case 3D, and the like. It is composed of multiple parts. A hole 22 for supplying engine oil is provided at the rear portion of the top wall 3C of the cover body 3H, and a plurality of ribs 3a are formed inside (see FIG. 5).

The intake passage k has a cover intake passage portion 19A provided on the gas outlet cover 3B of the head cover 3, and has a gas passage 26 in the cover of the blow-by gas outlet portion 3A formed in the front portion of the cover main body 3H and a cover. It communicates with the intake passage portion 19A. The cover intake passage portion 19A is configured as a part of the compressor upstream intake passage 19 that connects the air cleaner 23 (see FIG. 2) and the supercharger 12. The intake passage k is a concept including all passages for sending the air a to the combustion chamber (not shown), such as the air cleaner 23 and the intake manifold 15.

On the upper part of the front part of the cover body 3H, there is a bottom wall (“a partition partition between the space portion 3h inside the head cover 3 other than the gas passage 26 in the cover and the gas passage 26 in the cover”” located in the middle of the upper and lower parts of the head cover 3. Example) An open-covered box-shaped blow-by gas outlet portion 3A partitioned by 25 is formed. Then, as shown in FIGS. 3 and 11, the gas outlet cover 3B is bolted onto the blow-by gas outlet portion 3A via the intermediate gas case 3D. A lower gasket 35 is interposed between the upper and lower parts of the blow-by gas outlet 3A and the intermediate gas case 3D, and an upper gasket 46 is interposed between the upper and lower parts of the intermediate gas case 3D and the gas outlet cover 3B.

Here, the main function (reflux portion to the intake passage k) in the blow-by gas recirculation device A will be briefly described. As shown in FIGS. 3, 4, and 11, the blow-by gas g flowing from the cylinder block 1 into the internal space of the head cover 3 passes through the inflow lead valve 31 and is a cover that is the internal space of the blow-by gas outlet portion 3A. Enter the inner gas passage 26. The blow-by gas g that has entered the gas passage 26 in the cover, which is also called a CCV (crankcase ventilation) chamber, is above the lower communication hole 38 of the lower gasket 35, the internal space (separation chamber) 50 of the intermediate gas case 3D, and the upper gasket 46. It is reduced to the cover intake passage portion 19A through the communication hole 49 and the communication passage 40 (described later), that is, to the intake passage k.

Next, the head cover 3 and the cover intake passage portion 19A will be described in detail.
As shown in FIGS. 3 to 8, an upward open blow-by gas outlet portion 3A is formed at the front end portion of the head cover 3 which has a rounded quadrangle (oval) in a plan view. The blow-by gas outlet portion 3A is a head cover as an open box-shaped portion having a gas passage 26 in the cover, which is a space portion surrounded by the vertically facing partition wall 24 and the bottom wall 25, and a joint surface 27, which is the upper end edge. It is formed in 3.

The gas passage 26 in the cover has a complex-shaped opening having curved protrusions, inclined portions, and the like avoiding a plurality of bolting points [see FIG. 6 (A)], and the bottom wall 25 is a shallow main body. The bottom surface 25A, the sink bottom surfaces 25B and 25B formed in the front and rear of the main bottom surface 25A in a deep state, and the groove bottom surface 25C straddling the front and rear sink bottom surfaces 25B and 25B in a state of extending back and forth on the right side of the main bottom surface 25A. And have. A circular inflow hole 31C that vertically penetrates the bottom wall 25 and an inflow reed valve 31 that acts on the inflow hole 31C are provided in a lateral (leftward) posture at the front and rear central portion of the main bottom surface 25A. In FIG. 6A, only the main part of the right half of the inflow reed valve 31 is drawn.

As shown in FIGS. 5, 8 and 10 (A), the inflow lead valve 31 is a space portion other than the gas passage 26 in the cover inside the head cover 3, that is, a cover body space 3h inside the cover body 3H. This is a gas check valve that allows blow-by gas g to flow into the gas passage 26 in the cover. The inflow reed valve 31 is composed of a thin inflow valve body 31A arranged on the main bottom surface 25A and a thick inflow valve guide 31B bolted to the bottom wall 25 at their roots. There is. The round tip 31a [see FIG. 6 (A)] of the inflow valve body 31A is arranged above the inflow hole 31C formed in the bottom wall 25 by opening to the main bottom surface 25A, and is usually formed with the lid of the inflow hole 31C. (Valve closed).

The thickness d of the peripheral edge portion 25a forming the inflow hole 31C in the bottom wall 25 (main bottom surface 25A) is set to be smaller than the diameter r of the inflow hole 31C (r> d). More specifically, the thickness d of the peripheral edge portion 25a may be set to half or less of the diameter r of the inflow hole 31C, preferably in the range of 0.5r ≧ d ≧ 0.3r. Then, the corner portion (upper corner portion) 47 on the downstream side is rounded in the blow-by gas flow direction in the inflow hole 31C. The upstream corner (lower corner) 48 may be rounded with a curvature larger than the downstream corner 47.

The sink bottom surface 25B includes an inclined surface (or an inclined curved surface) 32 that becomes lower from the front and back to the front or the rear of the inflow reed valve 31, and an extremely low surface 33 that continues to the lower side of the inclined surface 32 [FIG. 8]. See (A)]. Return holes 33a and 33a penetrating vertically are formed on the extremely low surfaces 33 and 33 of the bottom wall 25, and a return reed valve 34 (see FIG. 5) that acts on these return holes 33a is provided.

As shown in FIGS. 5 and 10B, the return reed valve 34 includes a return valve body 34A in contact with the extremely low surface 33 on the bottom wall 25, that is, the extremely low back surface 33A, and a thick return valve. The guide 34B and the guide 34B are 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 inflow reed valve 31, and usually, the return hole 33a is lightly closed by the tip portion 34a of the return valve body 34A, or the return valve body 34A is slightly small. The very slight return hole 33a is opened by the drooping displacement.

Each of the return reed valves 34 and 34 is arranged in a sideways posture in which the tip portion 34a is on the left side, and the oil component captured from the blow-by gas g in the gas passage 26 in the cover is allowed to flow down from the return hole 33a to flow down the cover main body. This is the place to return to the space 3h. The diameter of each return hole 33a is smaller than the diameter of the inflow hole 31C. The inflow valve body 31A and the return valve body 34A, and the inflow valve guide 31B and the return valve guide 34B may be the same parts, respectively.

As shown in FIGS. 3 to 5 and 11, the gas outlet cover 3B is bolted onto the blow-by gas outlet portion 3A via the intermediate gas case 3D, and the gas outlet cover 3B is the lid cover portion 36. And a cover intake passage portion 19A. 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 the head cover is bolted at three points sandwiching the three parts of the lower gasket 35, the intermediate gas case 3D, and the upper gasket 46. It is a place fixed to 3.

As shown in FIGS. 6B, 7 and 11, the cover intake passage portion 19A is such that the passage end portion 19b is closer to the front side, which is the outer side in the longitudinal direction of the head cover 3, with respect to the passage start end portion 19a. It is formed in a meandering passage that bends to. Specifically, the cover intake passage portion 19A includes a passage start end 19a and a passage end 19b extending in the left-right direction intersecting the head cover longitudinal direction (front-rear direction) and parallel to each other, and a passage start end 19a end and a passage end 19b. It has a passage middle portion 19c that is diagonally oriented in the front-rear, left-right, and front-rear directions that connect to the start end of the passage, and is formed in a meandering passage that has a crank shape (substantially Z shape) when viewed in the vertical direction.

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 of opening downward in a shape similar to that of the passage intermediate portion 19c in a plan view. It is formed. Further, the lid cover portion 36 is formed with gas passage recesses 36a located behind the opening 37 and opened downward, and bolt holes 3b are formed at three locations.

As shown in FIGS. 3, 6 (B) and 7 (B), the lid cover portion 36 is formed with a labyrinth-shaped connecting passage 40 communicating with the gas passage 26 in the cover. The connecting passage 40 is composed of a gas passage recess 36a of the gas outlet cover 3B and an upper gasket 46 serving as a lid for closing the opening of the recess 36a. The gas passage recess 36a of the gas outlet cover 3B communicates with the downstream end of the passage intermediate portion 19c in the gas flow direction.

As shown in FIGS. 6B and 9A, the right end of the gas passage recess 36a is located above the upper communication hole 49 of the upper gasket 46 and is connected to the passage intermediate portion 19c. It is narrow and has a front-rear end recess 42. Then, the gas outlet cover 3B has a right protrusion wall 43 that projects rearward toward the gas passage recess 36a along the terminal recess 42 and a front protrusion toward the gas passage recess 36a on the left side of the right protrusion wall 43. An intermediate protrusion wall 44 is formed. Therefore, the blow-by gas g flowing from the upper communication hole 49 passes through the connecting passage 40, which is a labyrinth-shaped (crank-shaped) curved path by the intermediate protrusion wall 44 and the right protrusion wall 43, and then proceeds to the passage intermediate portion 19c. It is configured as follows.

As shown in FIG. 6 (B), the heat insulating portion D between the portion of the connecting passage 40 excluding the end portion (terminal recess 42) on the intake passage side and the cover intake passage portion 19A, specifically, the passage intermediate portion 19c. Is provided. The heat insulating portion D is composed of a curved elongated hole (an example of a recess or a hole) 41 formed in the gas outlet cover 3B in a state of opening on the side surface of the gasket of the gas outlet cover 3B, and the opening 41a of the curved elongated hole 41 is formed. , Covered by the upper gasket 46.

The curved elongated hole 41 is formed between the passage intermediate portion 19c and the gas passage recess 36a in a state of being partitioned by thin front and rear rib-shaped walls 45 and 45, respectively. Due to the presence of the upper gasket 46, the curved elongated hole 41 becomes a closed space portion, so that the space portion becomes an air layer and the heat insulating portion D is formed.

As shown in FIGS. 9A and 11, the upper gasket 46 is a thin plate-shaped (sheet-shaped) gasket having one upper communication hole 49 and three bolt insertion holes 39. , The upper communication hole 49 is provided at a position substantially at the center on the left and right at the rear end.
As shown in FIGS. 9 (C) and 11, the lower gasket 35 is a thin plate-shaped (sheet-shaped) gasket having one lower communication hole 38 and three bolt insertion holes 39. The lower communication hole 38 is provided at the front end portion at a position slightly to the right. The diameter of the lower communication hole 38 is larger than the diameter of the upper communication hole 49, but the magnitude relationship between them is not limited to this.

As shown in FIGS. 9B and 11, the intermediate gas case 3D is a housing having three bolt insertion holes 39 on the periphery and one large internal space (functioning as an oil separation chamber) 50. Is. The internal space 50, which is a large hole penetrating vertically, has a trapezoidal shape with a short side on the right side when viewed in the vertical direction, and is formed of a metal material such as aluminum die casting or a synthetic resin material.

As shown in FIGS. 3 and 11, the lower gasket 35 is provided so as to be sandwiched between the upper and lower surfaces of the joint surface 27 of the blow-by gas outlet portion 3A and the bottom surface 51 of the intermediate gas case 3D, and the gas passage in the cover. The 26 and the internal space 50 are communicated only with the lower communication hole 38. The upper gasket 46 is provided so as to be sandwiched between the upper surface 52 of the intermediate gas case 3D and the joint lower surface 36b of the lid cover portion 36, and the communication passage 40 and the internal space 50 are communicated only through the upper communication hole 49. ing.

[About action and effect]
Conventionally, the water in the blow-by gas aggregates in the passage that returns the CCV to the intake air, and after adhering to the wall surface, it may freeze or grow into ice blocks, which block the blow-by gas passage and cause the engine internal pressure to become abnormal. There was a risk of rising.
It is effective to reduce the thickness (path length) of the part that is easily cooled in the blow-by gas passage. For example, it is a place where the flow velocity is increased and the heat transfer coefficient is increased, or a place where the wall surface temperature in the blow-by gas passage is low.

Specifically, the inflow hole 31C in the bottom wall 25 of the gas passage 26 in the cover can be mentioned. The conventional inflow hole has a longer (larger) hole length than the hole diameter, such as the discharge valve hole (31C) shown in Japanese Patent Application Laid-Open No. 2019-199809 [see FIG. 13 (A)]. there were. Therefore, there is a risk that freezing and ice blocks will grow in the inflow hole and be easily blocked.

Therefore, in the present invention, the diameter r of the inflow hole 31C and its thickness d are set to a dimensional relationship (eg, r = 6 mm, d = 2.5 mm) such that d <r / 2, and the downstream side. Since the corners 47 of the corner portion 47 are rounded, freezing and formation of ice blocks in the inflow hole 31C are suppressed. Even if an ice block is formed in the inflow hole 31C, it will be blown off by the increase in the internal pressure of the engine.

1B Crank case 3 Head cover 3h Space part (cover body space)
19A Cover intake passage 25 partition wall (bottom wall)
25a Peripheral part 26 Gas passage in cover 31 Gas check valve 31C Inflow hole 33a Return hole 47 Downstream corner k Intake passage

Claims (6)

An engine with a blow-by gas recirculation device configured to guide the blow-by gas in the crankcase to the intake passage after passing through the gas passage in the cover provided inside the head cover.
The intake passage has a cover intake passage portion provided on the head cover in a state of communicating with the gas passage in the cover.
An inflow hole that allows blow-by gas to flow into the gas passage in the cover is formed in the partition wall that separates the space portion other than the gas passage in the cover and the gas passage in the cover inside the head cover.
An engine with a blow-by gas recirculation device in which the thickness of the peripheral edge of the partition wall forming the inflow hole is set to be smaller than the diameter of the inflow hole. The engine with a blow-by gas recirculation device according to claim 1, wherein the partition wall has rounded corners on the downstream side in the blow-by gas flow direction in the inflow hole. The partition wall is provided with a gas check valve that allows blow-by gas to flow into the gas passage in the cover through the inflow hole and prevents the blow-by gas from flowing out from the inflow hole. The engine with a blow-by gas recirculation device according to 2. The invention according to any one of claims 1 to 3, wherein a return hole is provided in the partition wall at a position lower than the peripheral edge portion so that the oil trapped in the gas passage in the cover can fall. Engine with blow-by gas recirculation device. The engine with a blow-by gas recirculation device according to any one of claims 1 to 4, wherein the thickness of the peripheral edge portion is set to half or less of the diameter of the inflow hole. The engine with a blow-by gas recirculation device according to any one of claims 1 to 5, wherein the cover intake passage portion is detachably attached to the head cover.

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