JP7291642B2 - 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 mounted on a tractor or construction machine, or an engine for a vehicle.

The engine is equipped with a blow-by gas recirculation device that recirculates the blow-by gas that accumulates in the crankcase to the intake passage such as the intake manifold, mixes it with fresh air-fuel mixture and burns it, and prevents it from being released into the atmosphere as it is. It is 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 blow-by gas 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 is easily trapped inside the engine. As such an example, the one disclosed in Patent Document 1 is known.

JP 2008-163837 A

In general, recirculation passages such as piping for returning blow-by gas to the intake passage and head covers are exposed to the outside rather than inside the engine, so they tend to cool easily. In cryogenic conditions, the flow of blow-by gas cools the very cold head cover and piping, and moisture in the blow-by gas can freeze in the head cover and piping, thereby causing blockages.

An object of the present invention is to provide a structure in which the blow-by gas in the crankcase is returned to the intake passage after passing through the inside of the head cover. To provide an engine equipped with a blow-by gas recirculation device which is improved so as to minimize the inconvenience caused by freezing of the gas.

The present invention relates to an engine with a blow-by gas recirculation device configured to guide blow-by gas in a crankcase through an in-cover gas passage provided inside a head cover to an intake passage,
The intake passage has a cover intake passage portion provided in the head cover in a state of being communicated with the in-cover gas passage,
An inflow hole for allowing blow-by gas to flow into the in-cover gas passage is formed in a partition wall that separates the in-cover gas passage from a space inside the head cover other than the in-cover gas passage,
The thickness of the peripheral edge forming the inflow hole in the partition wall is set to be smaller than the diameter of the inflow hole,
The partition wall has rounded corners on a downstream side and an upstream side in the blow-by gas flow direction of the inflow hole, and the upstream corner is rounded with a larger curvature than the downstream corner. Characterized by

Regarding the present invention, refer to claims 2 to 5 for characteristic configurations and means other than the above-described configurations (means).

When the engine is running, the head cover becomes warm due to heat conduction from the cylinder head. Therefore, the blow-by gas flowing inside the head cover is also cooled and the water content is frozen, which may clog the gas passage in the cover.

In the present invention, the portion where the blow-by gas is circulated in the intake passage is set in the cover intake passage provided as a part of the head cover which is warmed by heat conduction from the cylinder head. Therefore, when the engine is running, even if the intake air is cold due to extreme cold, the temperature of the air flowing through the cover intake passage is increased, and the freezing of the water content in the blow-by gas recirculated to the cover intake passage is eliminated. become suppressed.

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

As a result, while adopting a structure in which the blow-by gas is returned to the intake passage after passing through the inside of the head cover, moisture in the blow-by gas is prevented from freezing at the point where it is returned to the intake passage and in the gas passage inside the cover, so that the moisture in the blow-by gas does not freeze at low temperatures. It is possible to provide an engine equipped with a blow-by gas recirculation device which is improved so as to minimize clogging of the blow-by gas passage due to freezing.

Front view of an industrial diesel engine A plan view of the engine shown in FIG. Left side view showing head cover with cover intake passage Top view of head cover with cover intake passage Bottom view of 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, (B) is a cross-sectional view along the ZZ line of (A) (A) Longitudinal cross-sectional view, (B) cross-sectional view showing the main part of the gas passage in the cover (A) Plan view of upper gasket, (B) Plan view of intermediate gas case, (C) Plan view of lower gasket (A) Enlarged side view showing structure of inflow reed valve, (B) Enlarged side view showing structure of return reed valve An exploded perspective view showing the structure of the head cover, cover intake passage, etc.

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an engine equipped with a blow-by gas recirculation device according to the present invention will be described below with reference to the drawings for a case where it is applied to an industrial diesel engine.

As shown in FIGS. 1 and 2, an industrial diesel engine (hereinafter simply referred to as engine) E has a cylinder head 2 mounted on the top of a cylinder block 1 and a head cover 3 on the top of the cylinder head 2. An oil pan 4 is assembled to the lower part of the cylinder block 1. - 特許庁A transmission case 5 is attached to the front end of the cylinder block 1 , an engine cooling fan 6 is arranged in front of the transmission case 5 , and a flywheel 7 is arranged in the rear of the cylinder block 1 . The upper half of the cylinder block 1 is composed of cylinders (notation is omitted), and the lower half thereof is composed of a crankcase 1B.

In the front part of the engine E, a drive pulley 8 attached to the shaft end of a crankshaft (not shown), a drive fan pulley 6A for the engine cooling fan 6, and a transmission belt 10 spanning the passive pulley 9A for the dynamo (alternator) 9, A water flange 21 and the like are provided. On the left side of the engine E, an exhaust manifold 11, a supercharger 12, a starter (not shown), an oil filter 14, and the like are installed. An intake manifold 15, a fuel injection pump housing 16, a stop solenoid 17, etc. are installed on the right side of the engine E, and three injectors 18, a compressor upstream intake passage 19, a compressor downstream intake passage 20, etc. are arranged above. there is

The compressor upstream intake passage 19 includes a cover intake passage portion 19A and a bent pipe 19B that connects the cover intake passage portion 19A and the compressor housing 12A of the supercharger 12 . The compressor downstream side intake passage 20 includes a starting end side pipe 20A that is connected to the compressor housing 12A and arranged across the head cover 3 directly above, and a terminal end side pipe 20B that connects the starting end side pipe 20A and the intake manifold 15. configured as follows. The bent tube 19B, the start side tube 20A, and the end side tube 20B may be made of a flexible material such as rubber or a metal pipe.

As shown in FIGS. 1, 2 and 3 to 5, the engine E has a blow-by gas recirculation system configured to guide the blow-by gas in the crankcase 1B through the inside of the head cover 3 to the intake passage k. Device A is equipped. The head cover 3 is a substantially bottomless box-shaped (upper lid-shaped) component that is assembled to the cylinder head 2 across a valve gear (not shown), and includes a cover main body 3H, a gas outlet cover 3B, an intermediate gas case 3D, and the like. It consists of multiple parts. An engine oil supply hole 22 is provided in 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 in the gas outlet cover 3B of the head cover 3, and includes an in-cover gas passage 26 of the blow-by gas outlet portion 3A formed in the front portion of the cover main body 3H, and the cover. It communicates with the intake passage portion 19A. The cover intake passage portion 19</b>A is configured as part of the compressor upstream side intake passage 19 that connects the air cleaner 23 (see FIG. 2 ) and the supercharger 12 . Note that the intake passage k is a concept including all passages such as the air cleaner 23 and the intake manifold 15 for sending the air a to the combustion chamber (not shown).

At the front upper part of the cover main body 3H, a bottom wall (a partition wall separating the cover inner gas passage 26 from the space 3h other than the cover inner gas passage 26 in the inside of the head cover 3) is provided. One example) A blow-by gas outlet 3A in the shape of an open box partitioned vertically by 25 is formed. As shown in FIGS. 3 and 11, a gas outlet cover 3B is bolted onto the blow-by gas outlet 3A via an intermediate gas case 3D. A lower gasket 35 is interposed between the blow-by gas outlet 3A and the intermediate gas case 3D, and an upper gasket 46 is interposed between the intermediate gas case 3D and the gas outlet cover 3B.

Here, a brief description will be given of the major functions of the blow-by gas recirculation device A (recirculation portion to the intake passage k). 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 reed valve 31 and passes through the cover, which is the internal space of the blow-by gas outlet 3A. Enter the inner gas passage 26 . The blow-by gas g that has entered the cover internal gas passage 26, which is also called a CCV (crankcase ventilation) chamber, passes through 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. Through the communication hole 49 and the communication passage 40 (described later), the air is returned to the cover intake passage portion 19A, that is, 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 upwardly open blow-by gas outlet 3A is formed at the front end of the head cover 3, which has a rounded square shape (oval shape) in plan view. The blow-by gas outlet portion 3A is an open box-shaped portion provided with an in-cover gas passage 26, which is a space surrounded by a vertical partition wall 24 and a bottom wall 25, and a joint surface 27, which is the upper edge of the head cover. 3 is formed.

The gas passage 26 in the cover has an opening of a complicated shape with curved protruding portions and sloping portions to avoid multiple bolting points (see FIG. 6(A)). The bottom surface 25A, the sink bottom surfaces 25B, 25B respectively formed on the front and rear sides of the main bottom surface 25A in a deep state, and the groove bottom surface 25C extending back and forth on the right side of the main bottom surface 25A and spanning the front and rear sink bottom surfaces 25B, 25B. and A circular inflow hole 31C penetrating vertically through the bottom wall 25 and an inflow reed valve 31 acting on the inflow hole 31C are provided in a horizontal (to the left) position at the front-rear central portion of the main bottom surface 25A. In addition, in FIG. 6(A), only the essential part of the right half of the inflow reed valve 31 is depicted.

As shown in FIGS. 5, 8, and 10A, the inflow reed valve 31 has a space inside the head cover 3 other than the cover internal gas passage 26, that is, a cover main body space 3h inside the cover main body 3H. 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 constructed by bolting a thin inflow valve body 31A arranged on the main bottom surface 25A and a thick inflow valve guide 31B to the bottom wall 25 at their root sides. there is A round tip portion 31a (see FIG. 6A) of the inflow valve body 31A is arranged above an inflow hole 31C formed in the bottom wall 25 so as to open in the main bottom surface 25A, and normally serves as a cover for the inflow hole 31C. (valve closed).

The thickness d of the peripheral 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 portion 25a is set to be less than half the diameter r of the inflow hole 31C, preferably in the range of 0.5r≧d≧0.3r. A downstream corner (upper corner) 47 in the blow-by gas flow direction of the inflow hole 31C is rounded. The upstream corner (lower corner) 48 may be rounded with a larger curvature than the downstream corner 47 .

The sink bottom surface 25B has an inclined surface (or an inclined curved surface) 32 which becomes lower as it goes from the front and back of the inflow reed valve 31 to the front or rear, and a very low surface 33 continuing to the lower side of the inclined surface 32 (FIG. 8). (A)]. Return holes 33a, 33a penetrating vertically are formed in the respective very low surfaces 33, 33 of the bottom wall 25, and a return reed valve 34 (see FIG. 5) acting 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 opposite side of the bottom wall 25 to the extremely low surface 33, that is, the extremely low back surface 33A, and a thick return valve. The guides 34B are bolted to the bottom wall 25 at their base sides. The return reed valve 34 is provided in an upside-down posture with respect to the inflow reed valve 31, and normally, 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 closed. The return hole 33a is opened very slightly due to the drooping displacement.

Each of the return reed valves 34, 34 is arranged in a horizontal orientation with the tip portion 34a on the left side, and causes the oil component captured from the blow-by gas g in the cover internal gas passage 26 to flow down from the return hole 33a to 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.

As shown in FIGS. 3 to 5 and 11, a gas outlet cover 3B is bolted onto the blow-by gas outlet 3A via an intermediate gas case 3D. and a cover intake passage portion 19A. The lid cover portion 36 has the same outline shape as the blow-by gas outlet portion 3A in a plan view, and is attached to the head cover by bolting at three locations across the three parts of the lower gasket 35, the intermediate gas case 3D, and the upper gasket 46. 3 is fixed.

As shown in FIGS. 6(B), 7 and 11, the cover air intake passage portion 19A is arranged such that the passage end portion 19b is closer to the outside in the longitudinal direction of the head cover 3 than the passage start portion 19a. It is formed in a meandering passage that bends to the More specifically, the cover air intake passage portion 19A includes a passage start end portion 19a and a passage end portion 19b extending in the lateral direction crossing the longitudinal direction (front-rear direction) of the head cover and parallel to each other, and the end of the passage start portion 19a and the passage end portion 19b. It is formed into a meandering passage having a crank shape (substantially Z shape) when viewed from the top and bottom direction.

The intermediate passage portion 19c is formed in a groove-like passage portion having a downward U-shaped cross section, and an opening 37 at the lower end thereof has a shape similar to that of the intermediate passage portion 19c in a plan view and opens downward. formed. Further, the lid cover portion 36 is formed with a gas passage recess 36a which is located behind the opening 37 and opens downward, and is formed with three bolt holes 3b.

As shown in FIGS. 3, 6B, and 7B, the lid cover portion 36 is formed with a labyrinth-like communication passage 40 that communicates with the in-cover gas passage 26 . The communication 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 direction of gas flow.

As shown in FIGS. 6(B) and 9(A), 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 intermediate passage portion 19c. It has a narrow, fore-and-aft terminating recess 42 . The gas outlet cover 3B has a right protruding wall 43 that protrudes rearward toward the gas passage recess 36a along the terminal recess 42, and a right protruding wall 43 that protrudes forward toward the gas passage recess 36a on the left side of the right protruding wall 43. An intermediate projection 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 path bent in a labyrinth shape (crank shape) by the middle protruding wall 44 and the right protruding wall 43, and then advances to the intermediate passage portion 19c. is configured as

As shown in FIG. 6(B), a heat insulating portion D is provided between a portion of the connecting passage 40 excluding the intake passage side end (terminating recess 42) and the cover intake passage portion 19A, more 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 hole) 41 formed in the gas outlet cover 3B in a state of opening to the side surface of the gasket of the gas outlet cover 3B. , are covered by an upper gasket 46 .

The curved elongated hole 41 is formed between the passage intermediate portion 19c and the gas passage recess 36a so as to be partitioned by thin front and rear rib-like walls 45, 45, respectively. Due to the presence of the upper gasket 46, the curved elongated hole 41 becomes a closed space.

As shown in FIGS. 9A and 11, the upper gasket 46 is a thin plate-like (sheet-like) gasket having one upper communication hole 49 and three bolt insertion holes 39. , the upper communication hole 49 is provided at a substantially central position between the left and right sides of the rear end portion.
As shown in FIGS. 9C and 11, the lower gasket 35 is a thin plate-like (sheet-like) gasket having one lower communication hole 38 and three bolt insertion holes 39. , the lower communication hole 38 is provided at a position slightly to the right at the front end. The diameter of the lower communication hole 38 is larger than the diameter of the upper communication hole 49, but the size 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 and one large internal space (functioning as an oil separation chamber) 50 on the periphery. is. The internal space 50, which is a large vertically penetrating hole, has a trapezoidal shape with a short side on the right side when viewed in the vertical direction, and is made of a metal material such as aluminum die-cast or a synthetic resin material.

As shown in FIGS. 3 and 11, the lower gasket 35 is sandwiched between the joint surface 27 of the blow-by gas outlet portion 3A and the bottom surface 51 of the intermediate gas case 3D to provide a cover-inside gas passage. 26 and the internal space 50 are communicated only through the lower communicating hole 38 . The upper gasket 46 is 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 actions and effects]
Conventionally, moisture in the blow-by gas condenses in the passage returning the CCV to the intake, and after adhering to the wall surface, it may freeze and grow into ice blocks, blocking the blow-by gas passage and causing abnormal engine internal pressure. was likely to rise.
It is effective to reduce the thickness (path length) of easily cooled portions in the blow-by gas passage. For example, there are locations where the flow velocity is throttled and the heat transfer coefficient increases, and locations where the wall surface temperature in the blow-by gas passage is low.

Specifically, an inflow hole 31C in the bottom wall 25 of the in-cover gas passage 26 is mentioned. A conventional inflow hole has a hole length longer (larger) 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 possibility that the inflow hole may be easily blocked by freezing and ice blocks growing.

Therefore, in the present invention, the diameter r and the thickness d of the inflow hole 31C are set to have a dimensional relationship that satisfies d<r/2 (eg, r=6 mm, d=2.5 mm). Since the corners 47 are rounded, freezing in the inflow hole 31C and generation of ice blocks are suppressed. Even if an ice block occurs inside the inflow hole 31C, it will be blown away by the engine internal pressure increase.

1B crankcase 3 head cover 3h space (cover main body space)
19A Cover intake passage portion 25 Partition (bottom wall)
25a Peripheral edge 26 In-cover gas passage 31 Gas check valve 31C Inflow hole 33a Return hole 47 Downstream corner
48 Upstream corner
k Intake passage

Claims (5)

An engine with a blow-by gas recirculation device configured to guide blow-by gas in a crankcase to an intake passage through an in-cover gas passage provided inside a head cover,
The intake passage has a cover intake passage portion provided in the head cover in a state of being communicated with the in-cover gas passage,
An inflow hole for allowing blow-by gas to flow into the in-cover gas passage is formed in a partition wall that separates the in-cover gas passage from a space inside the head cover other than the in-cover gas passage,
The thickness of the peripheral edge forming the inflow hole in the partition wall is set to be smaller than the diameter of the inflow hole ,
The partition wall has a downstream corner and an upstream corner rounded in the flow direction of the blow-by gas in the inflow hole, and the upstream corner is rounded with a larger curvature than the downstream corner. Engine with recirculation device. 2. The partition wall is provided with a gas check valve that allows blow-by gas to flow into the in-cover gas passage through the inflow hole and prevents outflow from the inflow hole. An engine with a blow-by gas recirculation device as described. 3. The blow-by gas recirculation device according to claim 1, wherein a return hole is provided at a portion of said partition wall lower in height than said peripheral edge portion, through which oil trapped in said gas passage inside said cover can fall. engine. The engine with a blow-by gas recirculation device according to any one of claims 1 to 3, wherein the thickness of the peripheral portion is set to be 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 4 , wherein the cover intake passage portion is detachably attached to the head cover .

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