JP2012057574A - Engine blow-by gas reflux device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine blow-by gas reflux device capable of reducing oil consumption and enhancing ventilation efficiency in a head cover and a crankcase.SOLUTION: An engine blow-by gas reflux device is provided with an oil mist shielding plate 13 opposing to a head cover ceiling wall 10 installed in a head cover 2, a blow-by gas passage gap 18 formed between the head cover ceiling wall 10 and the oil mist shielding plate 13, a PCV valve arranged downstream of the blow-by gas passage gap 18, a pipe exit 17 of a fresh air introduction pipe 14 opposed to a part 13a of the oil mist shielding plate 13, and a fresh air introduction gap 19 formed between the part 13a of the oil mist shielding plate 13 and the head cover ceiling wall 10. The fresh air introduction gap 19 is separated from the blow-by gas passage gap 18 with partition walls 20, 21.

Description

The present invention relates to an engine blow-by gas recirculation device, and more particularly, to an engine blow-by gas recirculation device that can reduce oil consumption and increase ventilation efficiency in a head cover and a crankcase.
In this specification and claims, PCV valve is an abbreviation for positive crankcase ventilation valve, and adjusts the flow rate of blow-by gas to the intake passage according to the intake negative pressure in the intake passage. A valve that says

  Conventionally, as a blow-by gas recirculation device for an engine, a PCV valve and a fresh air introduction pipe are arranged in the head cover, and the PCV valve communicates with the downstream intake passage downstream of the throttle valve via the blow-by gas passage. In addition, the upstream intake passage on the upstream side is communicated with the inside of the head cover via the fresh air introduction passage and the fresh air introduction pipe, and the inside of the head cover is communicated with the crankcase via the communication passage. Is introduced into the head cover and the crankcase through the fresh air introduction passage and the fresh air introduction pipe in order, and the gas in the head cover and the crankcase is fresh air during the back flow from the head cover to the upstream intake passage. There is one that is introduced into the upstream intake passage through the introduction pipe and the fresh air introduction passage in order (for example, Patent Literature 1).

According to this type of blow-by gas recirculation device, blow-by gas in the head cover or crank case is recirculated to the combustion chamber by ventilation in the head cover or crank case, and the blow-by gas is added to the engine oil accumulated in the head cover or crank case. There is an advantage that it is possible to suppress the deterioration of the engine oil due to the contamination.
However, in this prior art, there is no means for suppressing the oil mist from being taken out from the head cover at the time of recirculation or reverse flow of blowby gas, and means for suppressing the fresh air from being short-circuited from the fresh air introduction pipe to the PCV valve. There is no problem.

JP 2010-101226 A (refer to FIG. 2 and FIG. 3)

[Problem] Oil consumption is high.
Since there is no means for suppressing the oil mist taken out from the head cover when the blow-by gas is recirculated or backflowed, the oil mist is taken out from the head cover together with the blow-by gas, resulting in a large amount of oil consumption.

<Problem> The ventilation efficiency in the head cover and crankcase is low.
Since there is no means for suppressing fresh air from being short-circuited from the fresh air introduction pipe to the PCV valve, the ventilation efficiency in the head cover and the crankcase is low.

  An object of the present invention is to provide an engine blow-by gas recirculation device that can reduce oil consumption and increase ventilation efficiency in a head cover and a crankcase.

Invention specific matters of the invention according to claim 1 are as follows.
As illustrated in FIG. 1A, a PCV valve (3) and a fresh air introduction pipe (14) are arranged on a head cover (2) assembled to a cylinder head (1), and the PCV valve (3) is a blow-by gas passage. (4) is connected to the downstream intake passage (6) downstream of the throttle valve (5), and the upstream intake passage (7) upstream of the throttle valve (5) is connected to the fresh air introduction passage ( 8) and the fresh air introduction pipe (14) are communicated with the inside of the head cover (2), and the inside of the head cover (2) is communicated with the crankcase (9) via the communication path (11).
Fresh air (12) in the upstream intake passage (7) is introduced into the head cover (2) and the crankcase (9) through the fresh air introduction passage (8) and the fresh air introduction pipe (14) in this order. And
During the reverse flow from the inside of the head cover (2) to the upstream side intake passage (7), the blow-by gas (45) in the head cover (2) and in the crankcase (9) flows into the fresh air introduction pipe (14) and the fresh air introduction passage ( 8) in order to be introduced into the upstream intake passage (7) through the engine blowby gas recirculation device,

As illustrated in FIG. 2, an oil mist shielding plate (13) facing the head cover ceiling wall (10) is attached in the head cover (2), and as illustrated in FIG. 3 (A), the head cover ceiling wall (10). A blow-by gas passage gap (18) (18) (18) is formed between the oil mist shielding plate (13) and the PCV valve (3) downstream of the blow-by gas passage gaps (18) (18) (18). And place
As illustrated in FIGS. 2, 3A and 3B, a pipe outlet (17) of the fresh air introduction pipe (14) is opposed to a part (13a) of the oil mist shielding plate (13), and this oil A fresh air introduction gap (19) is formed between a part (13a) of the mist shielding plate (13) and the head cover top wall (10),
By dividing the fresh air introduction gap (19) from the blow-by gas passage gaps (18), (18) and (18) by the partition walls (20) and (21), the fresh air introduction gap (19 The fresh air (12) introduced into the head cover (2) from the fresh air introduction gap (19) without short-circuiting from the blow-by gas passage gap (18) (18) (18) to the PCV valve (3). And a blow-by gas recirculation device for an engine, wherein the blow-by gas recirculation device is introduced into the crankcase (9).

(Invention of Claim 1)
The invention according to claim 1 has the following effects.
<Effect> Oil consumption can be reduced.
As illustrated in FIG. 2, an oil mist shielding plate (13) facing the head cover ceiling wall (10) is attached in the head cover (2), and as illustrated in FIG. 3 (A), the head cover ceiling wall (10). A blow-by gas passage gap (18) (18) (18) is formed between the oil mist shielding plate (13) and the PCV valve (3) downstream of the blow-by gas passage gaps (18) (18) (18). Therefore, when the blow-by gas (45) is recirculated, the oil mist taken out from the head cover (2) is suppressed by the oil mist shielding plate (13).
Moreover, as illustrated in FIGS. 2, 3A, and 3B, the pipe outlet (17) of the fresh air introduction pipe (14) is opposed to a part (13a) of the oil mist shielding plate (13), Since a fresh air introduction gap (19) is formed between a part (13a) of the oil mist shielding plate (13) and the head cover top wall (10), the head cover (2) Of oil mist from the oil mist is suppressed by a part (13a) of the oil mist shielding plate (13).
For these reasons, oil consumption can be reduced.

<Effect> The ventilation efficiency in the head cover and the crankcase can be increased.
As illustrated in FIGS. 2, 3A and 3B, the fresh air introduction gap (19) is divided into blow-by gas passage gaps (18), (18) and (18) by partition walls (20) and (21). As a result, the fresh air (12) introduced into the fresh air introduction gap (19) from the fresh air introduction pipe (14) is short-circuited from the blow-by gas passage gaps (18), (18), (18) to the PCV valve (3). Without introducing the air into the head cover (2) and the crankcase (9) from the fresh air introduction pipe (14), so that the ventilation efficiency in the head cover (2) and the crankcase (9) is improved. Can be increased.

(Invention of Claim 2)
The invention according to claim 2 has the following effect in addition to the effect of the invention according to claim 1.
<Effect> It is possible to reduce valve seating noise and combustion noise released from the ceiling wall of the head cover.
As illustrated in FIGS. 5A and 5B, since the partition walls 20 and 21 are attached to the oil mist shielding plate 13, the oil mist shielding function is provided by the reinforcing function of the partition walls 20 and 21. The vibration of the plate (13) is suppressed, and the valve seating noise and the combustion noise released from the head cover ceiling wall (10) through the vibration of the oil mist shielding plate (13) can be reduced.

(Invention of Claim 3)
The invention according to claim 3 has the following effect in addition to the effect of the invention according to claim 1 or claim 2.
<Effect> Oil consumption can be reduced.
As illustrated in FIG. 4B, a PCV valve (3) is provided downstream of the blow-by gas outlet passage outlet (28), and an upper floating port (23) of the blow-by gas floating chamber (23) from the blow-by gas passage gap (18) ( 25) The blow-by gas (45) that has floated to the bottom of the blow-by gas is turned downward along the ceiling wall (27) of the blow-by gas float chamber (23) and then flows into the blow-by gas outlet passage inlet (26). Oil mist in the blow-by gas (45) inverted downward along the ceiling wall (27) of the blow-by gas levitation chamber (23) is condensed on the ceiling wall (27) of the blow-by gas levitation chamber (23), and the head cover (2 ) Is prevented from taking out oil mist, and oil consumption can be reduced.

FIG. 1B is a schematic side view of a PCV valve used in this apparatus, which is a schematic view of an engine equipped with a blowby gas recirculation apparatus according to an embodiment of the present invention. It is a principal part vertical side view of the head cover used with the engine of FIG. 3A is a bottom view of the main part of the head cover of FIG. 2, and FIG. 3B is a cross-sectional view taken along line BB of FIG. 3A. 4A is a plan view of the main part of the head cover of FIG. 2, and FIG. 4B is a cross-sectional view taken along line BB of FIG. 4A. 5A is a bottom view of the oil mist shielding plate used in the engine of FIG. 1, FIG. 5B is a view in the direction of arrow B in FIG. 5A, and FIG. 5C is attached to the oil mist shielding plate. 5 (D) is a view in the direction of arrow D in FIG. 5 (C), and FIG. 5 (E) is a view in the direction of arrow E in FIG. 5 (A). It is a top view of the engine of FIG. It is a side view of the engine of FIG.

  FIGS. 1-7 is a figure explaining the engine provided with the blowby gas recirculation apparatus which concerns on embodiment of this invention, and this embodiment demonstrates a vertical in-line water-cooled 4-cylinder diesel engine.

As shown in FIGS. 6 and 7, this engine has a cylinder head (1) assembled to the top of a cylinder block (35), a head cover (2) assembled to the top of the cylinder head (1), and a cylinder block (35). The oil pan (36) is assembled to the lower part of the cylinder, the transmission case (48) is assembled to the front end of the cylinder block (35), the engine cooling fan (37) is arranged at the front of the transmission case (48), and the cylinder block ( 35) A flywheel (38) is arranged at the rear part. The transmission case (48) is a gear case of the timing transmission gear train.
The upper half part of the cylinder block (35) is a cylinder part (39), and the lower half part is a crankcase (9).
An intake manifold (40) is arranged on one side of the cylinder head (1), a throttle body (42) is attached to the front of the main pipe (41) of the intake manifold (40), and the front of the throttle body (42) A gas mixer (43) is attached. As shown in FIG. 1, an air cleaner (44) communicates with the gas mixer (43).

As shown in FIG. 1A, a PCV valve (3) and a fresh air introduction pipe (14) are arranged on a head cover (2) assembled to a cylinder head (1), and the PCV valve (3) is connected to a blow-by gas passage ( 4) is connected to the downstream intake passage (6) downstream of the throttle valve (5), and the upstream intake passage (7) upstream of the throttle valve (5) is connected to the fresh air introduction passage (8). ) And the fresh air introduction pipe (14) are communicated with each other in the head cover (2), and the inside of the head cover (2) is communicated with the crankcase (9) via the communication path (11).
Fresh air (12) in the upstream intake passage (7) is introduced into the head cover (2) and the crankcase (9) through the fresh air introduction passage (8) and the fresh air introduction pipe (14) in this order. Is done.
Gas is exchanged between the head cover (2) and the crankcase (9) due to the pulsation of the crankcase (9) generated by the pumping action of the piston (30). The fresh air (12) introduced in (2) is introduced into the crankcase (9).

  During the reverse flow from the inside of the head cover (2) to the upstream side intake passage (7), the blow-by gas (45) in the head cover (2) and in the crankcase (9) flows into the fresh air introduction pipe (14) and the fresh air introduction passage ( 8) are introduced into the upstream intake passage (7) in order. The upstream intake passage (7) is downstream of the air cleaner (44) and upstream of the gas mixer (43).

As shown in FIG. 1B, the PCV valve (3) is provided with a valve seat (3b) on the upstream side in the valve case (3a) and a valve passage (3c) on the downstream side of the valve case (3a). The valve element (3d) is accommodated in the valve passage (3c) so as to be able to advance and retreat, and the valve element (3d) is urged toward the valve seat (3b) by the urging spring (3e).
The PCV valve (3) is configured to cause the valve body (3d) to be unbalanced by the intake negative pressure of the downstream intake passage (6), the urging force of the urging spring (3e), and the internal pressure of the head cover (2). Advancing and retreating, and changing the passage cross-sectional area of the valve passage (3c) around the valve body (3d) and the passage cross-sectional area between the valve body (3d) and the valve seat (3b), the downstream side intake from the head cover (2) The flow rate of blow-by gas (45) sucked into the passage (6) is adjusted.

When the throttle valve (5) has a small opening and a light load, the intake negative pressure in the downstream intake passage (6) downstream of the throttle valve (5) becomes larger (close to the vacuum), and the valve body (3d) Since the passage cross-sectional area of the valve passage (3c) around the valve element (3d) is narrower on the downstream side of the passage (3c), the blow-by sucked from the crankcase (9) to the downstream intake passage (6). The flow rate of gas (45) is small.
When the load of the throttle valve (5) increases due to the medium load and the governor mechanism (not shown), the negative intake pressure in the downstream intake passage (6) decreases (close to atmospheric pressure), and the valve element (3d) Is positioned upstream of the valve passage (3c), and the passage cross-sectional area of the valve passage (3c) around the valve body (3d) is widened, so that it is sucked from the head cover (2) to the downstream intake passage (6). The flow rate of blow-by gas (45) is increased as compared with the case of low load.

  When the load becomes high and the opening of the throttle valve (5) is near the fully open position by the governor mechanism, the intake negative pressure in the downstream intake passage (6) becomes even smaller (close to atmospheric pressure), and the valve element (3d) Although located further upstream of the valve passage (3c) and the passage cross-sectional area of the valve passage (3c) around the valve body (3d) becomes larger, the valve body (3d) approaches the valve seat (3b) and the valve body Since the passage cross-sectional area between (3d) and the valve seat (3b) is small, the flow rate of the blow-by gas (45) sucked into the downstream intake passage (6) from the head cover (2) is medium load Less than. Further, when the load is high, the amount of blow-by gas (45) leaking from the combustion chamber (49) to the crankcase (9) increases. As described above, when the load is high, the flow rate of the blow-by gas (45) sucked into the downstream side intake passage (6) is increased even though the amount of the blow-by gas (45) leaking to the crankcase (9) increases. Therefore, the backflow from the inside of the head cover (2) to the upstream side intake passage (7) occurs, and the increase of the internal pressure of the crankcase (9) is suppressed.

As shown in FIG. 2, an oil mist shielding plate (13) facing the head cover ceiling wall (10) is attached in the head cover (2), and the head cover ceiling wall (10) and the oil are removed as shown in FIG. Blow-by gas passage gaps (18), (18) and (18) are formed between the mist shielding plate (13) and the PCV valve (3) is arranged downstream of the blow-by gas passage gaps (18), (18) and (18). is doing.
As shown in FIGS. 2, 3A and 3B, a pipe outlet (17) of the fresh air introduction pipe (14) is opposed to a part (13a) of the oil mist shielding plate (13), and the oil mist A fresh air introduction gap (19) is formed between a part (13a) of the shielding plate (13) and the head cover top wall (10).
By dividing the fresh air introduction gap (19) from the blow-by gas passage gaps (18), (18) and (18) by the partition walls (20) and (21), the fresh air introduction gap (19 The fresh air (12) introduced into the head cover (2) from the fresh air introduction gap (19) without short-circuiting from the blow-by gas passage gap (18) (18) (18) to the PCV valve (3). And in the crankcase (9).

As shown in FIGS. 6 and 7, the head cover (2) has the crankshaft axis (31) oriented in the front-rear direction, the engine cooling fan (37) in the front, and the flywheel (38) in the rear. Is formed long at the front and rear, and as shown in FIG. 2, an oil mist shielding plate (13) is disposed behind the head cover (2).
As shown in FIG. 3 (A), the oil mist shielding plate (13) is formed long in the front-rear direction, and the blow-by gas floating chamber peripheral wall (22) is disposed above the center in the front-rear direction.
A central longitudinal rib (33) that longitudinally runs in the front-rear direction at the center in the left-right direction of the head cover ceiling wall (10) protrudes downward from the head cover ceiling wall (10).

As shown in FIG. 2, a fastening portion receiving boss (50) is coupled to the central longitudinal rib (33). The rocker arm bracket (51) is accommodated in the head cover (2), the rocker arm (52) is swingably attached to the rocker arm bracket (51), and the push rod (53) and the rocker arm (52) are moved from the valve cam (not shown). The intake and exhaust valves (not shown) are driven to open and close via A stud bolt (54) is attached to the cylinder head (1), and the stud bolt (54) is inserted into the rocker arm bracket (51), the oil mist shielding plate (13) and the head cover ceiling wall (10), and the stud bolt (54). The rocker arm bracket (51) is fixed to the cylinder head (1) by the fastening force of the bracket fastening nut (55) screwed in the middle, and the cap nut (56) fastened to the tip of the stud bolt (54) is fastened. The head cover (2) is fixed to the cylinder head (1) by force. The bracket fastening nut (55) is housed in the fastener housing boss (51).
The push rod (53) is accommodated in a push rod chamber (57) formed in the cylinder head (1) and the cylinder block (35). The push rod chamber (57) is accommodated in the head cover (2) and the crankcase (9). ) Is used as a communication path (11) for communicating inside.

As shown in FIG. 3 (A), the front portion of the gap between the head cover ceiling wall (10) and the oil mist shielding plate (13) is divided into left and right by the central longitudinal rib (33), and these are blow-by. The gas passage gaps (18) and (18) are provided, and inlets (18a) and (18a) are provided at the front end portions thereof.
Of the gap between the head cover ceiling wall (10) and the oil mist shielding plate (13), the rear portion is divided into left and right by the central longitudinal rib (33), one is the blow-by gas passage gap (18), and the other is The surplus gap (34) is provided with an inlet (18a) at the rear end portion of the blow-by gas passage gap (18), the rear portion of the surplus gap (34) is defined as a fresh air introduction gap (19), and a fresh air introduction gap ( 19) The outlet (19a) is provided at the rear end.
The outlet (18b) of each blow-by gas passage gap (18) is disposed above the center in the front-rear direction of the oil mist shielding plate (13).

As shown in FIGS. 2 and 3 (A), a central transverse rib (47) that traverses in the left-right direction at the center in the front-rear direction of the head cover ceiling wall (10) protrudes downward from the head cover ceiling wall (10). The central transverse rib (47) is opposed to the inlets (18a) and (18a) of the front blow-by gas passage gaps (18) and (18) from the front side, and the oil mist enters from these inlets (18a and 18a). Is suppressed.
A rear end transverse rib (46) that traverses in the left-right direction at the rear end of the head cover ceiling wall (10) protrudes downward from the head cover ceiling wall (10), and this rear end transverse rib (46) is blown by the rear blow-by gas. The inlet (18a) of the passage gap (18) and the outlet (19a) of the fresh air introduction gap (19) are opposed from the rear side, and the blow-by gas (45) enters from these inlet (18a) and outlet (19a). Is suppressed.

As shown in FIGS. 5A and 5B, the partition walls 20 and 21 are attached to the oil mist shielding plate 13.
As shown in FIGS. 5C and 5D, the front partition wall (20) is bent upward from the front edge of the mounting plate (32), and the lateral partition wall (21) is mounted on the mounting plate (32). ) Is bent upward from the lateral edge portion, and the attachment plate (32) is attached to the upper surface of the rear end portion of the oil mist shielding plate (13) by welding. A fresh air introduction gap (19) is formed between the front partition wall (20) and the lateral partition wall (21) so that the excess air gap (34) and blow-by gas passage gap (18) on the front side of the fresh air introduction gap (19). 18) (18).
As shown in FIG. 3 (B), the lateral partition wall (21) and the central longitudinal rib (33) are abutted from above and below, and from the fresh air introduction gap (19) to the lateral blow-by gas passage gap (18). New air (12) is prevented from entering.

As shown in FIGS. 2 and 4 (B), the blowby gas floating chamber peripheral wall (22) protrudes upward from the head cover ceiling wall (10), and as shown in FIG. 3 (A), the blowby gas floating chamber (23 ) Are provided with outlets (18b), (18b) and (18b) of blow-by gas passage gaps (18), (18) and (18), and as shown in FIGS. ) Is provided with a blowby gas outlet passage wall (24), a blowby gas outlet passage wall (29) is provided in the blowby gas outlet passage wall (24), and the blowby gas outlet passage wall (24) and the blowby gas floating chamber peripheral wall ( 22), an upper levitation port (25) is provided, and a blowby gas outlet passage inlet (26) communicating with the blowby gas levitation chamber (23) is formed on the upper surface of the blowby gas outlet passage wall (24). The passage entrance (26) is connected to the blow-by gas levitation chamber (23). It is made to face the Ikabe (27).
As shown in FIG. 4 (B), a PCV valve (3) is arranged downstream of the blow-by gas outlet passage outlet (28), and the upper floating port (23) of the blow-by gas floating chamber (23) is opened from the blow-by gas passage gap (18). The blow-by gas (45) that has risen to 25) is turned downward along the ceiling wall (27) of the blow-by gas floating chamber (23), and then flows into the blow-by gas outlet passage inlet (26).

(1) Cylinder head
(2) Head cover
(3) PCV valve
(4) Blow-by gas passage
(5) Throttle valve
(6) Downstream intake passage
(7) Upstream intake passage
(8) Fresh air passage
(9) Crankcase
(10) Head cover ceiling wall
(11) Communication passage
(12) Fresh
(13) Oil mist shielding plate
(13a) Part of oil mist shielding plate
(14) Fresh air introduction pipe
(17) Pipe outlet
(18) Blowby gas passage
(19) Fresh air introduction gap
(20) City partition
(21) City partition
(22) Blow-by gas levitation chamber peripheral wall
(23) Blowby gas levitation chamber
(24) Blowby gas outlet passage wall
(25) Upper lift
(26) Blowby gas outlet passage entrance
(27) Ceiling wall
(28) Blow-by gas outlet passage exit
(29) Blowby gas outlet passage
(45) Blowby gas

Claims (3)

A PCV valve (3) and a fresh air introduction pipe (14) are arranged on the head cover (2) assembled to the cylinder head (1). The PCV valve (3) is connected to the throttle valve (5) via the blow-by gas passage (4). The upstream intake passage (7) upstream of the throttle valve (5) is communicated with the downstream intake passage (6) downstream of the throttle valve (5). The fresh air introduction passage (8) and the fresh air introduction pipe (14) The head cover (2) communicates with the crankcase (9) through the communication path (11).
Fresh air (12) in the upstream intake passage (7) is introduced into the head cover (2) and the crankcase (9) through the fresh air introduction passage (8) and the fresh air introduction pipe (14) in this order. And
During the reverse flow from the inside of the head cover (2) to the upstream side intake passage (7), the blow-by gas (45) in the head cover (2) and in the crankcase (9) flows into the fresh air introduction pipe (14) and the fresh air introduction passage ( 8) in order to be introduced into the upstream intake passage (7) through the engine blowby gas recirculation device,
An oil mist shielding plate (13) facing the head cover ceiling wall (10) is mounted in the head cover (2), and a blow-by gas passage gap (18) is provided between the head cover ceiling wall (10) and the oil mist shielding plate (13). (18) and (18) are formed, and the PCV valve (3) is arranged downstream of the blow-by gas passage gaps (18), (18) and (18),
The pipe outlet (17) of the fresh air introduction pipe (14) is opposed to a part (13a) of the oil mist shielding plate (13), and a part (13a) of the oil mist shielding plate (13) and the head cover top wall ( 10) to form a fresh air introduction gap (19),
By dividing the fresh air introduction gap (19) from the blow-by gas passage gaps (18), (18) and (18) by the partition walls (20) and (21), the fresh air introduction gap (19 The fresh air (12) introduced into the head cover (2) from the fresh air introduction gap (19) without short-circuiting from the blow-by gas passage gap (18) (18) (18) to the PCV valve (3). And a blow-by gas recirculation device for an engine, wherein the blow-by gas recirculation device is introduced into the crankcase (9). In the engine blowby gas recirculation device according to claim 1,
A blow-by gas recirculation device for an engine, wherein partition walls (20) and (21) are attached to an oil mist shielding plate (13). In the blowby gas recirculation device for an engine according to claim 1 or 2,
The blowby gas floating chamber peripheral wall (22) protrudes upward from the head cover ceiling wall (10), and the outlet (18b) of the blowby gas passage gaps (18) (18) (18) is formed below the blowby gas floating chamber (23). 18b) (18b), a blowby gas outlet passage wall (24) is provided in the upper part of the blowby gas floating chamber (23), and a blowby gas outlet passage (29) is provided in the blowby gas outlet passage wall (24). An upper floating port (25) is provided between the gas outlet passage wall (24) and the blow-by gas floating chamber peripheral wall (22), and communicates with the blow-by gas floating chamber (23) on the upper surface of the blow-by gas outlet passage wall (24). Open the blow-by gas outlet passage inlet (26), and make the blow-by gas outlet passage inlet (26) face the ceiling wall (27) of the blow-by gas floating chamber (23),
A PCV valve (3) is provided downstream of the blow-by gas outlet passage outlet (28), and the blow-by gas (45) floating from the blow-by gas passage gap (18) to the upper floating port (25) of the blow-by gas floating chamber (23). Is blown down along the ceiling wall (27) of the blow-by gas levitation chamber (23) and then flows into the blow-by gas lead-out passage inlet (26).

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