JP5778009B2 - Internal combustion engine head cover structure - Google Patents

Description

  The present invention relates to a head cover structure for an internal combustion engine in which a fresh air introduction chamber and a blow-by discharge chamber constituting a breather device are arranged in parallel to a cylinder head cover along a cylinder row direction.

  In a reciprocating engine (hereinafter simply referred to as an engine) mounted on an automobile or the like, blow-by gas is unavoidably leaked into the crankcase from the gap between the cylinder and the piston during the compression stroke and the expansion stroke. Blow-by gas contains unburned air-fuel mixture (ie, HC), acid, moisture, etc., so it is necessary to introduce it into the intake system from the crankcase and burn it with fresh air to suppress engine oil deterioration and air pollution. . However, because blow-by gas contains mist-like engine oil (oil mist) floating in the crankcase, when introduced directly into the intake system, the engine oil is contaminated by engine oil. There was a problem that the amount of consumption increased.

  Therefore, in recent engines, a blow-by system that introduces blow-by gas generated in the crankcase into the intake system by intake negative pressure downstream of the throttle valve and introduces fresh air into the crankcase from the intake system is adopted. A breather chamber (hereinafter referred to as blow-by discharge chamber) for separating engine oil from blow-by gas in the blow-by gas discharge flow path is provided in the cylinder head cover, and a breather device for returning the separated engine oil into the engine is provided. Yes.

  However, during high-speed and high-load operation, the pressure difference between the upstream and downstream of the throttle valve becomes small, and the amount of blow-by gas generated increases, so the blow-by gas flows back through the fresh air introduction passage, and the intake system There is a case where the exhaust is discharged to the upstream side of the throttle valve and sent to the combustion chamber together with the intake air. Therefore, a chamber (hereinafter referred to as a fresh air introduction chamber) to be provided in a flow path for introducing fresh air into the crank chamber is provided in parallel with the cylinder head cover together with the blow-by discharge chamber, and the fresh air introduction flow is introduced into the fresh air introduction chamber. There has been proposed a head cover structure in which a partition wall is provided so that a path is folded in a U shape in a fresh air introduction chamber, and a baffle plate that separates oil from backflowed blowby gas is provided (Patent Document 1).

Japanese Patent Publication No. 7-99087

  When a large amount of blow-by gas flows back into the fresh air introduction passage during high load operation, oil that cannot be separated is sucked into the intake system from the fresh air inlet of the fresh air introduction chamber. However, if the blow-by discharge chamber and the fresh air introduction chamber constituting the breather device are provided in the cylinder head cover, the capacity of the fresh air introduction chamber cannot be increased, so that too much oil is sucked into the intake system and combustion occurs. There is a risk of defects. Further, if a gas-liquid separation structure that completely separates oil from blow-by gas is provided in the fresh air introduction chamber, the capacity of the fresh air introduction chamber tends to be insufficient.

  The present invention has been devised to solve such problems included in the prior art, and the blow-by gas that has flowed back even with a short flow path length can be efficiently removed without increasing the capacity of the fresh air introduction chamber. An object of the present invention is to provide a head cover structure for an internal combustion engine capable of gas-liquid separation.

In order to solve such a problem, according to one aspect of the present invention, a fresh air introduction chamber (41) for circulating fresh air to be sent to a crank chamber, and oil is separated from blow-by gas discharged from the crank chamber. to blow discharge chamber (40), but a head cover structure are formed respectively along the cylinder row direction in an internal combustion engine which is arranged in the cylinder head cover (20) (1), the fresh air introduction chamber, the A throttle part (44) formed by protrusions (27, 28) protruding from at least one of the ceiling surface (41a) and the floor surface (41b) at an intermediate position in the cylinder row direction , and the cylinder row more than the throttle part formed on one side of the direction, the first chamber of replacement air intake taking in fresh air from the intake system of the internal combustion engine (42) is formed (45), the other side of the cylinder row direction than the throttle portion And a second chamber (46) formed with a fresh air outlet (43) communicating with the crank chamber. The second chamber is provided between the fresh air outlet and the throttle portion. In FIG. 5, the barriers (31, 32) projecting from the inner wall defining the second chamber are provided.

  According to this configuration, when blow-by gas flows backward to the fresh air introduction chamber during high-load operation, blow-by gas that has flowed into the second chamber from the fresh air discharge port reduces the flow rate and separates the oil, and also by the barrier. The oil is separated, then passes through the throttle portion and flows into the first chamber, and the oil is separated again by reducing the flow velocity. By adjusting the flow rate of blow-by gas in the fresh air introduction chamber in this manner, gas-liquid separation can be performed efficiently even with a short flow path length.

According to an aspect of the present invention, wherein the second chamber, without small that protrudes with a small projecting size than the barrier from the surface facing the tip of the barrier on the inner wall defining said second chamber Both may have a configuration in which one sub-barrier (35, 36) is provided.

  According to this configuration, the blow-by gas that flows along the barrier collides with the sub-barrier, so that oil adheres to the sub-barrier, so that the gas-liquid separation of the blow-by gas that flows back through the fresh air introduction chamber is efficiently performed. be able to.

  Further, according to one aspect of the present invention, a plurality of the sub-barriers may be provided, and a larger number of the sub-barriers may be arranged on the throttle portion side than the fresh air outlet side with respect to the barrier.

  According to this configuration, oil can be captured more effectively by arranging a large number of sub-barriers on the throttle portion side. Further, by reducing the number of sub-barriers on the fresh air outlet side, the resistance of fresh air that normally flows can be reduced.

  According to another aspect of the present invention, the barrier includes a lower barrier (31) extending from the floor surface and an upper barrier (32) extending from the ceiling surface, and the fresh air outlet side The lower barriers and the upper barriers can be arranged alternately and in at least two rows from the side toward the throttle unit.

  According to this configuration, the blow-by gas that flows backward flows while being bent a plurality of times by the lower barrier and the upper barrier, whereby oil separation of the blow-by gas is promoted by inertia force.

According to another aspect of the present invention, the second chamber is formed closer to the fresh air outlet than the barrier, and an interval (L1) between the lower barrier and the upper barrier in the cylinder row direction . A first separation chamber (47) having a larger inner dimension (L2), formed on the throttle portion side than the barrier, and larger than an interval between the lower barrier and the upper barrier in the cylinder row direction It can be set as the structure which has the 2nd separation chamber (48) which has an internal dimension (L3).

  According to this configuration, the flow rate of the blow-by gas is relatively high in the flow path flowing while being bent by the barrier, and the oil is separated by a large inertia force, and when flowing into the first separation chamber from the fresh air outlet, When flowing into the second separation chamber from the bent flow path, the flow rate of the blow-by gas is reduced to promote oil separation, so that the blow-by gas can be effectively gas-liquid separated.

  As described above, according to the present invention, it is possible to provide a head cover structure for an internal combustion engine that can efficiently perform gas-liquid separation of blow-by gas that has flowed backward even with a short flow path length without increasing the capacity of the fresh air introduction chamber.

The perspective view of the engine upper part which applied the cylinder head cover concerning an embodiment 1 is an enlarged cross-sectional view of the upper part of the engine, taken along line II-II in FIG. III-III sectional view in FIG. IV-IV sectional view in FIG. VV sectional view in FIG. VI-VI cross section in Fig. 3 Action explanatory drawing of embodiment corresponding to FIG.

  Hereinafter, an embodiment in which a cylinder head cover 20 according to the present invention is applied to an engine 1 of an automobile will be described in detail with reference to the drawings.

  The engine 1 according to the present embodiment is a DOHC four-valve DOHC type in-line four-cylinder gasoline engine, and is coupled to the upper end of the cylinder block 2 and the upper end of the cylinder head 2 as shown in FIG. The cylinder head cover 20 is provided. The cylinder head 2 has a substantially rectangular parallelepiped shape whose longitudinal direction is the cylinder row direction, an intake port (not shown) is formed on one surface along the longitudinal direction, and the exhaust port 3 is formed on the other surface along the longitudinal direction. Is open. Hereinafter, in the case of indicating the direction, the arrow shown in FIG. 1, that is, the state in which the engine 1 is horizontally placed with the exhaust port 3 directed in the traveling direction of the vehicle body and the cylinder axis line is vertical is used as a standard. It shall be. In each figure, attention is paid to the upper part of the engine 1, and the lower part of the cylinder block and the like are omitted, and the cylinder head 2 is also omitted as appropriate.

  A pump housing 5 for supporting a fuel pump 4 driven by an exhaust camshaft 8 (see FIG. 2) is fastened to the left end of the upper surface of the cylinder head 2, and the cylinder head cover 20 is connected to the right side of the pump housing 5. It is connected to the side surface and covers the remaining part of the upper surface of the cylinder head 2. Between the cylinder head 2 and the cylinder head cover 20, there is formed a valve operating chamber 10 in which an intake camshaft 7, an exhaust camshaft 8, an intake rocker shaft 9 (both see FIG. 2), an intake / exhaust valve (not shown), and the like are provided. ing.

  As shown in FIG. 2, the cylinder head cover 20 has a front side wall 21f, an upper wall 21u, and a rear side wall 21r, and has a U-shaped cross section that opens downward to define the upper part of the valve operating chamber 10. The lower part 21 includes a head cover front upper part 22 and a head cover rear upper part 23 that extend along the longitudinal direction of the cylinder head 2 and are separated from each other in the front-rear direction and coupled to the upper surface of the head cover lower part 21.

The engine 1 includes a breather device that introduces blow-by gas into the intake system by intake negative pressure downstream of the throttle valve, and introduces fresh air into the crank chamber from the intake system upstream of the throttle valve. . The head cover front upper portion 22 has an annular joint surface 22a with respect to the head cover lower portion 21 and has a box shape with an inner wall protruding upward. A space defined by the head cover front upper portion 22 and the head cover lower portion 21 upper wall 21u is a blow-by discharge chamber 40 that separates engine oil from blow-by gas in a blow-by discharge passage of the breather device. On the other hand, the head cover rear upper part 23 has an annular joint surface 23a with respect to the head cover lower part 21 and has a box shape in which the inner wall projects upward, and the head cover rear upper part 23 and the head cover lower part 21 upper wall 21u A space defined in between is a fresh air introduction chamber 41 that separates engine oil from blow-by gas flowing backward in the fresh air introduction flow path of the breather device. In this way, the blow discharge chamber 40 and fresh air introduction chamber 41 formed me along the longitudinal direction of the cylinder head 2, respectively are arranged in the cylinder head cover 20.

  As shown in FIG. 1, a tubular connecting portion 24 is formed on the left side wall 23l of the head cover rear upper portion 23 so as to protrude substantially horizontally to the left. The connection portion 24 is connected to an intake hose (not shown) having one end connected to the upstream side of the throttle valve of the intake system. That is, a fresh air inlet 42 (FIG. 2) for taking fresh air from the intake system into the fresh air introduction chamber 41 is formed in the left side wall 23l of the head cover rear upper part 23 where the connecting portion 24 is formed. Further, at an intermediate position in the left-right direction of the head cover rear upper portion 23, the upper wall 23u and the front wall 23f of the head cover rear upper portion 23 are recessed toward the fresh air introduction chamber 41 to form a recess 25.

  As shown in FIG. 2, a space in which the ignition coil 11 and the harness 12 connected thereto are provided is formed between the head cover front upper part 22 and the head cover rear upper part 23. This space is covered by the engine cover 13 provided so as to extend along the upper surfaces of the head cover front upper part 22 and the head cover rear upper part 23. The engine cover 13 is fastened to the cylinder head cover 20 by a plurality of cover fastening bolts 14, one of which is fastened to the head cover rear upper part 23. A bolt boss portion 26 for forming a screw hole 26 a into which the cover fastening bolt 14 is screwed is provided below the concave portion 25 of the head cover rear upper portion 23, and the head of the cover fastening bolt 14 is disposed in the concave portion 25. This prevents the cover fastening bolts 14 from protruding from the upper surface of the cylinder head cover 20. Further, the cover fastening bolt 14 fastens the harness holder 15 that supports the harness 12 together with the head cover rear upper part 23 in a state of being sandwiched between the engine cover 13 and the head cover rear upper part 23.

  The portions defining the blow-by discharge chamber 40 and the fresh air introduction chamber 41 in the upper wall 21u of the head cover lower portion 21 are recessed downward so as not to interfere with the intake camshaft 7 and the exhaust camshaft 8, respectively. The capacity of the fresh air introduction chamber 41 is made as large as possible. In the present embodiment, the rocker shaft is provided only on the intake side, and the exhaust camshaft 8 is disposed at a position lower than the intake camshaft 7, so that the blow-by discharge chamber 40 in the upper wall 21u of the head cover lower portion 21 is provided. The portion to be defined is recessed downward with a larger cross-sectional area than the portion that defines the fresh air introduction chamber 41. On the other hand, the portion defining the fresh air introduction chamber 41 in the upper wall 21u of the head cover lower portion 21 is a portion corresponding to the cam lobe while the rear portion where the intake camshaft 7 does not extend downward is recessed below the front portion. In addition, a portion corresponding to the cam cap 16 (and its fastening bolt) projects into the fresh air introduction chamber 41.

  As shown in FIGS. 3 and 4, the fresh air intake 42 opens at the upper left end of the fresh air introduction chamber 41. On the other hand, on the lower surface near the right end of the fresh air introduction chamber 41, a fresh air discharge port 43 communicating with the crank chamber via the valve operating chamber 10 is formed so as to penetrate the upper wall 21 u of the head cover lower part 21. Therefore, during normal operation of the engine 1, fresh air introduced from the intake system circulates in the fresh air introduction chamber 41 from the left side to the right side as indicated by a white arrow.

  At a middle position in the left-right direction (longitudinal direction) of the fresh air introduction chamber 41, a ceiling protrusion 27 that is formed by the recess 25 and the bolt boss portion 26 and protrudes from the ceiling surface 41a is formed. Further, at two intermediate positions in the left-right direction of the fresh air introduction chamber 41, a portion corresponding to the cam cap 16 of the upper wall 21 u of the head cover lower part 21 is formed and protrudes from the floor surface 41 b of the fresh air introduction chamber 41. An upstream floor projection 28 and a downstream floor projection 29 are formed. The upstream floor protrusion 28 is formed at a position that substantially coincides with the ceiling protrusion 27 in the longitudinal direction of the fresh air introduction chamber 41, and fresh air is introduced by the upstream floor protrusion 28 and the ceiling protrusion 27. A throttle portion 44 is formed in the chamber 41. Accordingly, the fresh air introduction chamber 41 is formed on the left side (upstream side) of the first chamber 45 where the fresh air inlet 42 is formed and on the right side (downstream side) of the throttle portion 44, and the fresh air outlet 43 Is divided into the second chamber 46 formed.

  In the second chamber 46, a lower barrier 31 that extends upward from the floor 41 b of the fresh air introduction chamber 41 and extends in the front-rear direction is provided at a position where the downstream floor protrusion 29 in the left-right direction is provided. Is provided. The lower barrier 31 is formed integrally with the head cover lower part 21, and as shown in FIG. 5, the side edge has a width dimension with a gap between the inner surface of the head cover rear upper part 23. . This is to facilitate the assembly of the head cover lower part 21 and the head cover rear upper part 23 even if there is a manufacturing error. The lower barrier 31 is formed with a height such that the upper edge thereof is lower than the ceiling surface 41 a of the fresh air introduction chamber 41, and the new barrier between the upper edge and the ceiling surface 41 a of the fresh air introduction chamber 41 is formed. The flow path of Qi is narrowed.

  Further, on the inner side surface of the head cover rear upper portion 23, a gap between the side edge of the lower barrier 31 and the inner surface of the head cover rear upper portion 23 is located at a position close to the upstream side and the downstream side with respect to the lower barrier 31. Further, a protruding plate 33 protruding with a large protruding dimension is formed so as to extend in the vertical direction. Thereby, the clearance gap between the both-sides edge of the lower side barrier 31 and the inner surface of the head cover rear upper part 23 becomes a labyrinth shape, and distribution | circulation of fresh air or blow-by gas is prevented.

Furthermore, the position where the pair toward the leading end of the lower barrier 31 in the ceiling surface 41a of the fresh-air introduction chamber 41, a small projecting than the height of the small and fresh air flow path than the projecting dimension of the lower barrier 31 Plural (here, five) upper sub-barriers 35 projecting with dimensions are formed at predetermined intervals in the left-right direction. The upper sub-barrier 35 is arranged at a position where the fourth one counted from the upstream side coincides with the lower barrier 31 in the left-right direction. That is, three upper sub-barriers 35 are disposed upstream of the upper sub-barrier 35, and one upper sub-barrier 35 is disposed downstream of the upper sub-barrier 35.

  The second chamber 46 is further provided with an upper barrier 32 that extends downward from the ceiling surface 41 a and extends in the front-rear direction on the upstream side (left side) of the lower barrier 31. The upper barrier 32 is formed integrally with the rear upper portion 23 of the head cover, and as shown in FIG. 6, the side edge has a gap with the inner surface of the lower portion of the head cover 21, and the lower edge is fresh. It is formed in a size that is higher than the floor surface 41 b of the introduction chamber 41, and restricts the fresh air flow path between the lower edge thereof and the floor surface 41 b of the fresh air introduction chamber 41.

  In addition, a protrusion dimension larger than the gap between the side edge of the upper barrier 32 and the inner surface of the head cover lower portion 21 is located on the inner side surface of the head cover lower portion 21 at positions close to the upstream side and the downstream side with respect to the upper barrier 32. A projecting plate 34 projecting in the vertical direction is formed so as to extend in the vertical direction.

Furthermore, the position where the pair toward the leading end of the upper barrier 32 in the floor surface 41b of the fresh air introduction chamber 41, with a smaller projecting size than the height of the small and fresh air flow path than the projecting dimension of the upper barrier 32 A plurality of (here, five) lower sub-barriers 36 that protrude are formed at predetermined intervals in the left-right direction. The lower sub-barrier 36 is arranged so that the upper barrier 32 is located between the fourth and fifth ones counted from the upstream side. That is, four lower sub-barriers 36 are arranged on the upstream side of the upper barrier 32, and one lower sub-barrier 36 is arranged on the downstream side of the upper barrier 32.

  Here, in the left-right direction, the interval between the lower barrier 31 and the upper barrier 32 is L1, the interval between the right side wall 41r of the fresh air introduction chamber 41 and the lower barrier 31 is L2, and the throttle of the fresh air introduction chamber 41 is reduced. Assuming that the distance between the portion 44 and the upper barrier 32 is L3, the lower barrier 31 and the upper barrier 32 are provided at positions where L1 <L2 <L3. That is, the second chamber 46 includes the first separation chamber 47 and the second separation chamber having inner dimensions L2 and L3 larger than the distance L1 between the lower barrier 31 and the upper barrier 32 in the left-right direction due to the barriers 31 and 32, respectively. 48.

  Next, the operation of the cylinder head 2 having such a configuration will be described with reference to FIG. During normal operation of the engine 1, as described above, fresh air introduced from the intake system and flowing in from the fresh air inlet 42 passes through the fresh air introduction chamber 41 from the left side to the right side as indicated by the white arrow in FIG. 3. The blow-by gas inside the engine 1 is scavenged by being discharged from the fresh air outlet 43. When the engine 1 is operated at a high speed and a high load, and the pressure difference between the throttle valves is reduced and the blow-by gas fresh air flows backward through the introduction passage of the blow-by gas fresh air, 7, flows from the right side to the left side as indicated by the black arrows in FIG. 7, and is discharged from the fresh air inlet 42 to the throttle valve upstream side of the intake system.

  At this time, the blow-by gas flowing into the fresh air introduction chamber 41 from the fresh air discharge port 43 is first separated in the first separation chamber 47 of the second chamber 46 at a reduced flow rate. Thereafter, the blow-by gas rises along the lower barrier 31, and after the flow path is restricted at the upper end of the lower barrier 31, the flow velocity is increased and collides with the ceiling surface 41 a of the fresh air introduction chamber 41. It descends between the lower barrier 31 and the upper barrier 32. At this time, since the blow-by gas makes a U-turn at the upper end of the lower barrier 31, the oil in the blow-by gas adheres to the ceiling surface 41a due to inertial force. Further, since the upper sub-barrier 35 is provided on the ceiling surface 41a, the oil adheres to the ceiling surface 41a (upper sub-barrier 35) more efficiently. In particular, since a large number of upper sub-barriers 35 are provided on the left side (downstream of blow-by gas) with respect to the lower barrier 31 in the left-right direction, oil is effectively captured.

  Similarly, blow-by gas descending along the lower barrier 31 and the upper barrier 32 makes a U-turn at a high flow velocity at the lower end of the upper barrier 32, and attaches oil to the lower sub-barrier 36. Then, the blow-by gas reduces the flow velocity in the second separation chamber 48 of the second chamber 46 to separate the oil again.

  Further, the blow-by gas increases the flow rate when passing through the throttle portion 44, and then decreases the flow rate again in the first chamber 45 to separate the oil. The blow-by gas is discharged to the upstream side of the throttle valve of the intake system through the fresh air inlet 42 formed in the upper part of the fresh air introduction chamber 41 where oil is hardly discharged.

  That is, since the throttle portion 44, the first chamber 45, and the second chamber 46 are formed in the fresh air introduction chamber 41, when the blow-by gas flows into the second chamber 46 and the first chamber 45, the flow velocity is reduced and the oil is reduced. The lower barrier 31 and the upper barrier 32 are formed in the second chamber 46, so that the oil is separated from the blow-by gas by colliding with the ceiling surface 41a and the floor surface 41b of the fresh air introduction chamber 41 at a high flow rate. Is done. By adjusting the flow rate of blow-by gas in the fresh air introduction chamber 41 in this way, gas-liquid separation is efficiently performed even with a short flow path length.

Further, in the present embodiment, the position against toward the distal end of the lower barrier 31 and upper barrier 32 in the second chamber 46, by the upper sub-barrier 35 and the lower sub-barrier 36 are formed respectively, the barrier 31 , 32, when blow-by gas flowing along the sub-barriers 35 and 36 collides with the sub-barriers 35 and 36, more of the oil contained in the blow-by gas adheres to the sub-barriers 35 and 36. Gas-liquid separation is efficiently performed.

  Further, in the present embodiment, a plurality of upper and lower sub-barriers 35 and 36 are provided, and a large number of lower and upper barriers 31 and 32 are arranged closer to the throttle portion 44 side than the fresh air outlet 43 side. This effectively captures the oil. In addition, since the number of sub-barriers 35 and 36 on the fresh air outlet 43 side is small, the resistance of fresh air that flows normally is small.

  In the present embodiment, since the lower barrier 31 and the upper barrier 32 are alternately arranged in two rows from the fresh air outlet 43 side toward the throttle portion 44 side, the blow-by gas that flows back through the fresh air introduction chamber 41 is provided. Bends multiple times, and the inertial force promotes oil separation of blow-by gas.

  In the present embodiment, the first separation chamber 47 having an inner dimension L2 larger than L1 in the longitudinal direction of the cylinder head 2 and the second separation chamber 48 having an inner dimension L3 also larger than L1 are the second Due to the formation in the chamber 46, the flow rate of blow-by gas is relatively high in the flow path that is bent while being bent by the lower and upper barriers 31 and 32, oil is separated by a large inertia force, and the fresh air discharge port When the flow into the first separation chamber 47 from 43 and the flow into the second separation chamber 48 from the bent flow path, the flow rate of the blow-by gas is reduced to promote oil separation. Gas-liquid separation is effectively performed.

  Although the description of the specific embodiment is finished as described above, the present invention is not limited to the above embodiment and can be widely modified. For example, in the above-described embodiment, the cylinder head 2 of the present invention is applied to an in-line four-cylinder gasoline engine, but it can also be applied to other internal combustion engines. In the above embodiment, the barriers 31 and 32 are arranged in two rows. However, it is also possible to arrange the barriers 31 and 32 in one row or three or more rows. In addition, the specific configuration, arrangement, and quantity of each device and member can be changed as appropriate without departing from the spirit of the present invention. On the other hand, all the components of the cylinder head 2 according to the present invention shown in the above embodiment are not necessarily essential, and can be appropriately selected as long as they do not depart from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder head 20 Cylinder head cover 27 Ceiling protrusion 28 Upstream floor surface protrusion 31 Lower barrier 32 Upper barrier 35 Upper sub barrier 36 Lower sub barrier 40 Blow-by discharge chamber 41 Fresh air introduction chamber 41a Ceiling surface 41b Floor surface 42 Fresh air inlet 43 Fresh air outlet 44 Restriction section 45 First chamber 46 Second chamber 47 First separation chamber 48 Second separation chamber L1 Distance between lower barrier and upper barrier L2 Inner dimension L3 of first separation chamber L3 Internal dimensions of the second separation chamber

Claims (3)

A fresh air introduction chamber for circulating fresh air to be sent to the crank chamber and a blow-by discharge chamber for separating oil from the blow-by gas discharged from the crank chamber are formed along the cylinder row direction and are arranged in parallel with the cylinder head. An internal combustion engine head cover structure, comprising:
The fresh air introduction chamber is formed at a middle portion in the cylinder row direction by a protruding portion that protrudes from at least one of the ceiling surface and the floor surface, and is formed on one side of the cylinder row direction from the throttle portion. A first chamber in which a fresh air intake for taking in fresh air from the intake system of the internal combustion engine is formed, and fresh air that is formed on the other side in the cylinder row direction than the throttle portion and communicates with the crank chamber A second chamber in which a discharge port is formed,
The second chamber includes a barrier projecting from an inner wall defining the second chamber between the fresh air outlet and the throttle, and a tip of the barrier on the inner wall defining the second chamber. A plurality of sub-barriers protruding from opposite surfaces with a protruding dimension smaller than the barrier ,
A head cover structure for an internal combustion engine , wherein a number of the sub-barriers are arranged closer to the throttle portion side than the fresh air outlet side with respect to the barrier . The barrier includes a lower barrier extending from the floor surface and an upper barrier extending from the ceiling surface, and the lower barrier and the upper barrier from the fresh air outlet side toward the throttle portion side. 2. The head cover structure for an internal combustion engine according to claim 1 , wherein and are arranged in at least two rows alternately. The second chamber is formed closer to the fresh air outlet than the barrier, and has a first separation chamber having an inner dimension larger than an interval between the lower barrier and the upper barrier in the cylinder row direction, wherein formed on the aperture portion side than the barrier, and having a second separation chamber having a larger internal dimension than the spacing in the cylinder row direction and the lower barrier and the upper barrier, claim 2 2. A head cover structure for an internal combustion engine according to 1.

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