JP6343327B2 - Internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine, and more particularly to a blow-by gas passage and an oil return passage of the internal combustion engine.

  In the cylinder block and cylinder head of the internal combustion engine, a passage for flowing blow-by gas from the crank chamber to the valve chamber and a passage for flowing oil from the valve chamber to the crank chamber are formed independently, and blow-by gas and oil There is one in which each interference is avoided and each flows smoothly (for example, Patent Document 1).

JP 2009-180172 A

  Before the blow-by gas is supplied to the intake system of the internal combustion engine, the blow-by gas is supplied to the gas-liquid separator to remove the liquid. In the gas-liquid separation device, liquid oil removed from the blow-by gas is generated, and a passage for returning this oil to the oil pan below the crank chamber is required. Thus, since an internal combustion engine requires a blow-by gas passage and an oil return passage, it is necessary to arrange these efficiently. At that time, it is desired to avoid the contact between the blow-by gas and the oil returned to the oil pan as much as possible, and to avoid the mixing of the oil droplets into the blow-by gas.

  In view of the above background, an object of the present invention is to suppress contact between blow-by gas and oil in an internal combustion engine.

  In order to solve the above problems, an aspect of the present invention is an internal combustion engine (1), which is a cylinder block (2) including a cylinder (2D) and a crank chamber (2C), and a cylinder axial direction of the cylinder block A cylinder head (4) coupled to the upper end of the cylinder head, and a valve chamber (18) and a connection passage (55A) coupled to the upper end of the cylinder head in the cylinder axial direction and separated from each other in cooperation with the cylinder head. A head cover (5) for defining the gas, a gas inlet port (61A) connected to the connection passage, a gas outlet port (61B, 61C) connected to the intake system (30) of the internal combustion engine, and the separated oil A gas-liquid separator (60) having an oil discharge port (61D) for discharging, and the cylinder block is connected to the cylinder from the crank chamber. The cylinder head has a first blow-by gas passage (41) and a first oil return passage (42) extending to an end face on the cylinder side, and the cylinder head extends in the cylinder axial direction to connect the first blow-by gas passage and the connection passage. A second blow-by gas passage (45) to be connected is separated from the valve operating chamber by a first partition wall (47), and is separated from the second blow-by gas passage by a second partition wall (48), and is connected to the oil discharge port. An oil return chamber (46) having a first oil return hole (51), a second oil return passage (43) connecting the valve operating chamber and the first oil return passage, and the first partition wall. Is formed with a second oil return hole (52) for connecting the oil return chamber and the valve operating chamber, and the second partition wall connects the oil return chamber and the second blow-by gas passage. Pores (53) is formed, the vent hole is characterized by being arranged above in the vertical direction than the second oil return hole.

  According to this aspect, the oil discharged from the gas-liquid separation device flows into the valve operating chamber via the oil return chamber, and flows into the crank chamber through the second oil return hole and the first oil return passage. Since the valve operating chamber is connected to the second blow-by gas passage through the second oil return hole, the oil return chamber, and the vent hole, the pressure is equal to that of the crank chamber. Since the vent hole is disposed above the second oil return hole in the vertical direction, the oil in the valve operating chamber is suppressed from flowing into the second blow-by gas passage, and mixing of the oil into the blow-by gas is suppressed. .

  Moreover, said aspect WHEREIN: The said 2nd oil return hole is good to be arrange | positioned in the part corresponding to the lower end part in the vertical direction of the said oil return chamber.

  According to this aspect, it is difficult for oil to stay in the oil return chamber.

  In the above aspect, the first oil return hole may be disposed below the vent hole in the vertical direction.

  According to this aspect, it is difficult for oil flowing into the oil return chamber from the first oil return hole to flow into the vent hole.

  Moreover, said aspect WHEREIN: The said vent hole is good to be arrange | positioned in the part corresponding to the upper end part in the perpendicular direction of the said oil return chamber.

  According to this aspect, it becomes difficult for the oil in the oil return chamber to flow into the vent hole.

  In the above aspect, the second blow-by gas passage may have a wider cross-sectional area in the upper part than in the lower part in the cylinder axial direction.

  According to this aspect, the flow velocity of the blow-by gas decreases while flowing through the second blow-by gas passage, so that the suspended oil droplets are pulled and separated from the blow-by gas by the flow of the blow-by gas.

  In the above aspect, the upper part of the second blow-by gas passage in the vertical direction branches into a plurality of passages (45A, 45B), and one branched passage (45A) connects to the connection passage and branches off. Another one passage (45B) may be connected to the vent hole.

  According to this aspect, it becomes difficult for the oil in the oil return chamber to flow from the vent hole to the second blow-by gas passage. Further, even if the oil in the oil return chamber flows from the vent hole to the second blow-by gas passage, it is suppressed from flowing to the connection passage.

  In the above aspect, the cylinder head includes a bearing wall (21) that rotatably supports the camshaft (19), and an upper portion of the second blow-by gas passage in the cylinder axial direction is the bearing wall. It is good to be formed inside.

  According to this aspect, since the second blow-by gas passage is formed using the bearing wall, the cylinder head can be reduced in size.

  In the above aspect, the bearing wall may also serve as an end wall (12) that constitutes an end of the cylinder head in the cylinder row direction.

  According to this aspect, since the second blow-by gas passage is formed in the end wall, the size of the cylinder head can be reduced.

  In the above aspect, the upper part of the oil return chamber in the cylinder axis direction may be formed inside the bearing wall.

  According to this aspect, since the oil return chamber is formed using the bearing wall, the size of the cylinder head can be reduced.

  In the above aspect, the second partition wall may be overhanging on the oil return chamber side with respect to the vertical direction.

  According to this aspect, it becomes difficult for the oil in the oil return chamber to reach the vent hole.

  In the above aspect, the first partition wall may extend in a direction perpendicular to the cylinder row direction so as to separate the second blow-by gas passage, the oil return chamber, and the valve operating chamber.

  According to this aspect, since the second blow-by gas passage and the oil return chamber are gathered and arranged on the side of the valve operating chamber via the first partition wall, the cylinder head can be reduced in size.

  In the above aspect, the cylinder head may support two camshafts (19), and the second partition wall may have a portion (48A) extending toward one center of the camshaft. .

  According to this aspect, the rigidity of the cylinder head is improved by the second partition against the load applied to the cylinder head via one of the camshaft from the chain or belt wound around the camshaft.

  In the above aspect, two camshafts (19) are supported on the cylinder head, and the sprocket or pulley (19A) provided at each end of the camshaft is connected to the end of the crankshaft. A chain or belt (19B) is wound together with a sprocket or pulley provided in the section, and the second partition is an imaginary that extrapolates the chain or belt extending in two directions from one sprocket or pulley of the camshaft It is preferable to have a portion extending in parallel with the bisector of the corner formed by the straight line.

  According to this aspect, the rigidity of the cylinder head is improved by the second partition against the load applied to the cylinder head via one of the camshaft from the chain or belt wound around the camshaft.

  In the above aspect, the second blow-by gas passage and the oil return chamber may be disposed adjacent to a cooling water passage (57) formed in the cylinder head.

  According to this aspect, the oil is heated by heat exchange between the oil passing through the oil return chamber and the cooling water passing through the cooling water passage. Further, the wall surface defining the second blow-by gas passage is maintained at a relatively high temperature by heat exchange with the cooling water passing through the cooling water passage, and condensation of moisture in the blow-by gas passing through the second blow-by gas passage and Freezing is suppressed.

  In the above aspect, the cooling water passage may be provided below the oil return chamber and on a side of the second blow-by gas passage.

  According to this aspect, the cooling water passage, the oil return chamber, and the second blow-by gas passage are efficiently arranged at the end of the cylinder head.

  Further, in the above aspect, the internal combustion engine is a V-type internal combustion engine having two cylinder banks offset from each other in the cylinder row direction, and each of the cylinder banks has the same shape of the cylinder head in the cylinder row direction. Preferably, the oil return chambers are formed on opposite side portions of the cylinder head.

  According to this aspect, since the oil return chamber is positioned on the higher side in the inclined cylinder head, the backflow of oil from the valve operating chamber to the oil return chamber is suppressed. In addition, the manufacturing cost can be reduced by forming the two cylinder banks from cylinder heads having the same shape.

  In the above aspect, the gas-liquid separation device may be disposed between the pair of cylinder heads.

  According to this aspect, since the gas-liquid separator is disposed in the recess between the pair of cylinder banks, the entire internal combustion engine can be reduced in size.

  According to the above configuration, contact between blow-by gas and oil is suppressed in the internal combustion engine.

The perspective view of the internal combustion engine which concerns on embodiment Configuration diagram of an internal combustion engine according to an embodiment Rear side view of an intake side of a cylinder head of an internal combustion engine according to an embodiment IV-IV sectional view of FIG. VV sectional view of FIG. VI-VI sectional view of FIG. Explanatory drawing showing the positional relationship between the cylinder head and chain

  Hereinafter, an embodiment of an internal combustion engine according to the present invention will be described with reference to the drawings.

(Schematic configuration of internal combustion engine)
As shown in FIGS. 1 and 2, the internal combustion engine 1 according to the present embodiment is a V-type 6-cylinder engine. The internal combustion engine 1 is disposed on the vehicle body such that the crankshaft extends in the left-right direction. The internal combustion engine 1 includes a cylinder block 2 having a front cylinder part 2A provided on the upper front side and a rear cylinder part 2B provided on the upper rear side, an oil pan 3 coupled to the lower part of the cylinder block 2, and a cylinder A front cylinder head 4 coupled to the front cylinder portion 2A of the block 2, a front head cover (front cam cover) 5 coupled to the upper portion of the front cylinder head 4, and a rear cylinder coupled to the rear cylinder portion 2B of the cylinder block 2 The head 6 has a rear head cover (rear cam cover) 7 coupled to the upper portion of the rear cylinder head 6. The front cylinder part 2A, the front cylinder head 4 and the front head cover 5 of the cylinder block 2 cooperate to form a front bank 8, and the rear cylinder part 2B, the rear cylinder head 6 and the rear head cover 7 of the cylinder block 2 are rear parts. Bank 9 is configured.

  The lower part of the cylinder block 2 forms a crankcase that opens downward, and forms a crank chamber 2C that receives the crankshaft therein. Each of the front cylinder part 2A and the rear cylinder part 2B has three cylinders 2D extending in the left and right directions and arranged in the left and right directions. Each cylinder 2D is connected to the crank chamber 2C. The axis A of each cylinder 2D of the front cylinder portion 2A is inclined with respect to the vertical direction (vertical surface) B by a predetermined angle centered on the crankshaft. The axis of each cylinder 2D of the rear cylinder portion 2B is inclined by a predetermined angle to the rear side with the crankshaft as the center with respect to the vertical plane. The upper end surfaces of the front cylinder portion 2A and the rear cylinder portion 2B form a fastening surface with the cylinder head, and each cylinder 2D is open. Each cylinder 2D receives a piston connected to a crankshaft by a connecting rod so as to be able to reciprocate. The lower part of the crank chamber 2C is closed by an oil pan 3. The oil pan 3 forms an oil storage chamber 3A connected to the crank chamber 2C. A transmission is coupled to the right end surface of the cylinder block 2.

  As shown in FIGS. 3 to 6, the front cylinder head 4 has a head lower portion 4A fastened to the upper end surface of the front cylinder portion 2A, and a head upper portion 4B provided on the upper portion of the head lower portion 4A. The head upper portion 4B has a pair of front and rear side walls 11, 11 protruding upward from the front edge and the rear edge of the upper end portion of the head lower portion 4A and extending left and right, and the left and right edges of the upper end portion of the head lower portion 4A. A pair of left and right end walls 12, 12 projecting upward from each other and extending forward and backward. The pair of side walls 11, 11, the pair of end walls 12, 12 and the upper surface 13 of the head lower portion 4 </ b> A cooperate to form a box shape that opens above a substantially rectangular parallelepiped that is long on the left and right.

  As shown in FIG. 5, a plurality of substantially hemispherical combustion chamber ceiling portions 15 are formed in the lower end surface of the head lower portion 4A so as to be recessed corresponding to the respective cylinders 2D. As shown in FIG. 3, the front cylinder head 4 has a plurality of intake ports 16 that extend rearward from the ceiling portions 15 of the combustion chambers and open on the rear side surface of the front cylinder head 4. Further, the front cylinder head 4 has a plurality of exhaust ports extending forward from the combustion chamber ceilings 15 and opening on the front side surface of the front cylinder head 4.

  As shown in FIGS. 4 and 5, the front head cover 5 is provided so as to cover the upper part of the front cylinder head 4. Specifically, the edge of the front head cover 5 is coupled to the pair of side walls 11, 11 and the upper end surfaces of the pair of end walls 12, 12. The front head cover 5 and the head upper portion 4B cooperate to define a front valve chamber 18. The front valve chamber 18 is provided with a valve mechanism for opening and closing valves provided in the intake port 16 and the exhaust port. The valve operating mechanism is of the DOHC type and has two camshafts 19. In addition to the camshaft 19, the valve operating mechanism is preferably driven by the camshaft 19 to have a rocker arm or the like that pushes the valve at a predetermined timing.

  The two camshafts 19 are arranged in parallel with the crankshaft, and are a rotating body 19A composed of a sprocket or a pulley, a winding transmission body 19B composed of a chain or a belt, and a sprocket or pulley provided on the crankshaft. Are connected to the crankshaft by a transmission mechanism. A plurality of bearing walls 21 project from the upper surface 13 of the head lower portion 4 </ b> A of the front cylinder head 4, and a plurality of bearing caps 22 project from the lower surface of the front head cover 5 corresponding to the bearing walls 21. Each bearing wall 21 and each bearing cap 22 are fastened to each other, and a bearing 23 that rotatably supports each camshaft 19 is formed on the fastening surface. The left and right end walls 12, 12 also serve as bearing walls 21 that support the left end and the right end of each camshaft 19.

  As shown in FIG. 2, the rear cylinder head 6 has a substantially front-rear symmetrical structure of the front cylinder head 4, and includes a plurality of combustion chamber ceiling portions 15 and the front side surface of the rear cylinder head 6 from the combustion chamber ceiling portions 15. And an exhaust port extending from the combustion chamber ceiling 15 to the rear side surface of the rear cylinder head 6. Similarly to the front cylinder head 4, the rear cylinder head 6 is covered with a rear head cover 7 and defines a rear valve chamber 25 in which a valve mechanism is provided between the rear cylinder head 6 and the rear head cover 7.

  The intake system 30 of the internal combustion engine 1 includes an intake inlet 31, an air cleaner 32, a turbocharger compressor 33, an intercooler 34, a throttle valve 35, and an intake manifold 36 in this order from the upstream side. As shown in FIG. 1, the intake manifold 36 is disposed between the front cylinder head 4 and the rear cylinder head 6, and is connected to the intake ports 16 of the front cylinder head 4 and the rear cylinder head 6. An exhaust system (not shown) of the internal combustion engine 1 includes, in order from the upstream side, an exhaust manifold, a turbocharger turbine, a catalytic converter, a silencer, and an exhaust outlet connected to exhaust ports of the front cylinder head 4 and the rear cylinder head 6. Have The internal combustion engine 1 includes an oil pump that pumps oil in the oil storage chamber 3 </ b> A to a sliding contact portion including the valve mechanism of the internal combustion engine 1. The oil pump is a known trochoid pump or the like, and pumps oil by receiving the rotational force of the crankshaft.

(Blow-by gas passage and oil return passage)
As shown in FIGS. 2 and 4, the front cylinder portion 2A of the cylinder block 2 extends vertically in the cylinder axial direction, the lower end is connected to the crank chamber 2C, and the upper end is open to the upper end surface of the front cylinder portion 2A. The first blow-by gas passage 41 and the first front oil return passage 42 are formed. The first blow-by gas passage 41 is formed on one end side (right end side in the present embodiment) in the cylinder row direction of the front cylinder portion 2A. In the present embodiment, the first front oil return passage 42 is disposed in front of the front end portion of the front cylinder portion 2A, specifically, the axis A of each cylinder 2D. The first front oil return passage 42 may be disposed between the adjacent cylinders 2D.

  As shown in FIGS. 2, 4, and 6, the front cylinder head 4 extends vertically in the cylinder axial direction, and includes a bottom portion of the front valve chamber 18 (the upper surface 13 of the head lower portion 4A) and a first front oil return passage. A second front oil return passage 43 is formed to connect to the second front oil return passage 43. The second front oil return passage 43 is provided at the front end portion of the head lower portion 4 </ b> A of the front cylinder head 4. Since the front cylinder head 4 is inclined forward, the bottom surface of the front valve chamber 18 is inclined forward. The second front oil return passage 43 opens at the lowest position in the vertical direction in the front valve chamber 18.

  As shown in FIG. 4, the front cylinder head 4 extends vertically in the cylinder axial direction, is connected to the first blow-by gas passage 41 at the lower end, and the upper end is the upper end surface of the right end wall 12 (bearing wall 21). A second blow-by gas passage 45 is formed in the opening. The second blow-by gas passage 45 is formed at an end portion on one end side in the cylinder row direction in the head lower portion 4 </ b> A of the front cylinder head 4. Specifically, the second blow-by gas passage 45 passes between the end surface on one side in the cylinder row direction and the combustion chamber ceiling portion 15 closest to the end surface in the head lower portion 4A of the front cylinder head 4. The second blow-by gas passage 45 extends upward from the head lower portion 4 </ b> A toward the upper end surface of the bearing wall 21 in one of the bearing walls 21. In the present embodiment, the upper part of the second blow-by gas passage 45 is formed in the right end wall 12 that also serves as the bearing wall 21. As shown in FIGS. 4 and 6, the second blow-by gas passage 45 is formed such that the upper part has a larger width in the front-rear direction and a larger width in the left-right direction than the lower part. That is, the upper part of the cross-sectional area (channel cross-sectional area) of the second blow-by gas passage 45 is larger than the lower part. Further, the upper end portion of the second blow-by gas passage 45 has a front branch portion 45A that extends forward and upward and opens at the upper end surface of the right end wall 12, and a rear branch portion 45B that extends rearward.

  As shown in FIG. 4, an oil return chamber 46 is formed behind the second blow-by gas passage 45 in the right end wall 12. The oil return chamber 46 is separated from the front valve chamber 18 by a first partition wall 47 that forms a side portion of the right end wall 12 on the front valve chamber 18 side. That is, the oil return chamber 46 is disposed on the right side of the front valve chamber 18 via the first partition wall 47 whose main surface is directed to the left and right. Similarly, the second blow-by gas passage 45 is disposed on the right side of the front valve chamber 18 via a first partition wall 47 whose main surface faces left and right. In order to separate the second blow-by gas passage 45 and the oil return chamber 46 from the front valve chamber 18, the first partition wall 47 has a main surface facing left and right and extending in a direction perpendicular to the cylinder row direction.

  The second blow-by gas passage 45 and the oil return chamber 46 are separated from each other by a second partition wall 48 that extends substantially vertically in the vertical direction. The upper part 48 </ b> A of the second partition wall 48 is bent rearward along the rear edge of the rear branching part 45 </ b> B of the second blow-by gas passage 45. That is, the upper part of the second partition wall 48 protrudes toward the oil return chamber 46 and overhangs on the oil return chamber 46 side. An upper part 48 </ b> A of the second partition wall 48 extends toward one center of the camshaft 19. As shown in FIG. 7, the upper part 48A of the second partition wall 48 has an imaginary angle formed by an imaginary straight line obtained by extrapolating a winding transmission body 19B extending in two tangential directions from one rotating body 19A of the camshaft 19. It is preferable to extend substantially parallel to the bisector. Moreover, it is preferable that the upper part 48A of the second partition wall 48 extends along a bisector of a virtual angle.

  As shown in FIGS. 3 and 4, a first oil return hole 51 is formed in the lower portion of the oil return chamber 46 and extends rearward and opens on the rear side of the head lower portion 4 </ b> A of the front cylinder head 4. The outer end (rear end) of the first oil return hole 51 is connected to an oil discharge port 61D of a gas-liquid separation device 60 described later via a pipe or the like. A second oil return hole 52 that penetrates the first partition 47 in the thickness direction (left and right) and connects the oil return chamber 46 and the front valve chamber 18 is formed in the lower portion of the first partition 47. At the upper end portion of the second partition wall 48, a vent hole 53 that penetrates the second partition wall 48 in the thickness direction (front and rear) and connects the oil return chamber 46 and the second blow-by gas passage 45 is formed. The vent hole 53 is drilled from the rear side of the front cylinder head 4 by a drill so as to penetrate the rear side wall 11, the oil return chamber 46, and the second partition wall 48. At that time, the hole 54A formed in the rear side wall 11 is closed by the plug 54B.

  As shown in FIG. 4, the second oil return hole 52 is formed at the lower end of the oil return chamber 46 in the vertical direction. The second oil return hole 52 is preferably formed in the rear part of the front cylinder head 4 and opens in the rear part of the front valve chamber 18. The vent hole 53 is disposed above the first oil return hole 51 and the second oil return hole 52 in the vertical direction. The first oil return hole 51 is disposed above the second oil return hole 52 in the vertical direction. The axis of the vent hole 53 extends substantially front and rear, and the axis of the second oil return hole 52 extends substantially left and right. For this reason, the axis of the vent hole 53 and the axis of the second oil return hole 52 are arranged in directions perpendicular to each other.

  An end of a cooling water passage 57 is disposed below the oil return chamber 46 and on the side of the second blow-by gas passage 45. The cooling water passage 57 is formed around the combustion chamber ceiling 15 of the front cylinder head 4 and the exhaust port extending from the combustion chamber ceiling 15. The end of the cooling water passage 57 has an oil return chamber 46 and a second blowby gas passage 45 so that heat exchange can be performed with a wall portion defining the oil return chamber 46 and a wall portion defining the second blowby gas passage 45. It is preferable that they are close to each other. The end of the cooling water passage 57 may open to the end of the front cylinder head 4 at the time of manufacture. For example, the end portion of the cooling water passage 57 may be a portion where a core support piece for forming the cooling water passage 57 is disposed when the front cylinder head 4 is cast. When the end of the cooling water passage 57 is open to the end of the front cylinder head 4 at the time of casting, the opening end of the end of the cooling water passage 57 is preferably closed by a plug in the manufacturing process.

  On the fastening surface of the bearing cap 22 of the front head cover 5, a passage groove 55 that is recessed upward is provided. The passage groove 55 and the upper end surface of the right end wall 12 cooperate to form a connection passage 55A. The connection passage 55A is separated from the front valve chamber 18. The open end of the upper end surface of the right end wall 12 of the second blow-by gas passage 45 is connected to the connection passage 55A. The passage groove 55 passes through the front head cover 5 in the thickness direction (up and down) at one end and opens on the upper surface of the front head cover 5.

  As shown in FIGS. 1 and 2, the open end of the connection passage 55 </ b> A on the upper surface of the front head cover 5 is connected to the gas-liquid separator 60. The gas-liquid separation device 60 includes a cyclone-type gas-liquid separation device that separates gas and liquid using centrifugal force, and a flow path meandering by a plurality of baffle plates, and gas and liquid using inertia force. And a gas-liquid separator or the like. The gas-liquid separation device 60 includes a gas inlet port 61A, a first gas outlet port 61B, a second gas outlet port 61C, and an oil discharge port 61D. In the gas-liquid separator 60, the blow-by gas flows from the gas inlet port 61A to the first gas outlet port 61B or the second gas outlet port 61C, and the oil separated from the blow-by gas is discharged from the oil discharge port 61D. The gas-liquid separator 60 is disposed behind the side wall 11 on the rear side of the front cylinder head 4. The gas-liquid separator 60 is disposed between the front cylinder head 4 and the rear cylinder head 6.

  An opening end of the connection passage 55 </ b> A on the upper surface of the front head cover 5 is connected to a gas inlet port 61 </ b> A of the gas-liquid separation device 60 via a first connection pipe 63. The first gas outlet port 61B is connected to the intake manifold 36 via the second connection pipe 64. The second connection pipe 64 is provided with a first check valve (PCV valve) 65 that allows a gas flow from the first gas outlet port 61B side to the intake manifold 36 side and blocks a reverse gas flow. It has been. The first check valve 65 opens when the pressure on the first gas outlet port 61B side is higher than the pressure on the intake manifold 36 side by a predetermined value or more. The second gas outlet port 61 </ b> C is connected to a portion of the intake system 30 between the air cleaner 32 and the compressor 33 via the third connection pipe 66. The third connection pipe 66 is provided with a second check valve 67 that allows a gas flow from the second gas outlet port 61C side to the intake system 30 side and prevents a reverse gas flow. The oil discharge port 61 </ b> D is connected to the first oil return hole 51 via the fourth connection pipe 68.

  As shown in FIG. 2, the rear valve chamber 25 formed between the rear cylinder head 6 and the rear head cover 7 is provided between the air cleaner 32 and the compressor 33 in the intake system 30 via the fifth connection pipe 72. Connected to the part. The fifth connection pipe 72 is provided with a third check valve 73 that allows gas flow from the intake system 30 side to the rear valve chamber 25 and prevents reverse gas flow. The rear valve chamber 25 is connected to the crank chamber 2C by a rear oil return passage 74 formed in the rear cylinder head 6 and the rear cylinder portion 2B of the cylinder block 2.

  The front cylinder head 4 constituting the front bank 8 and the rear cylinder head 6 constituting the rear bank 9 are formed in the same shape as each other, and are arranged in a mutually inverted form in the cylinder row direction. The front cylinder head 4 and the rear cylinder head 6 are arranged in the cylinder row direction so as to be offset in the direction in which the end portions provided with the respective oil return chambers 46 and the second blow-by gas passages 45 are separated from each other. . Each of the oil return chambers 46 is formed on the side of the front cylinder head 4 and the rear cylinder head 6 facing each other.

  According to the above configuration, as shown in FIG. 2, the blow-by gas in the crank chamber 2C sequentially passes through the first blow-by gas passage 41, the second blow-by gas passage 45, and the connection passage 55A, and the gas-liquid separator 60 Flow into. The blow-by gas is supplied from the first gas outlet port 61B to the intake manifold 36 during natural intake, and is supplied from the second gas outlet port 61C to the portion between the air cleaner 32 and the compressor 33 of the intake system 30 during supercharging. The

  The oil separated from the blow-by gas by the gas-liquid separator 60 passes through the oil discharge port 61D, the first oil return hole 51, the oil return chamber 46, and the second oil return hole 52 in order and flows into the front valve chamber 18. . The oil in the front valve chamber 18 flows through the second front oil return passage 43 and the first front oil return passage 42 to the oil storage chamber 3A below the crank chamber 2C.

  Fresh air flows from the portion between the air cleaner 32 and the compressor 33 of the intake system 30 to the fifth connecting pipe 72, the rear valve chamber 25, the rear oil return passage 74, the crank chamber 2C, the first blow-by gas passage 41, the second The blow-by gas passage 45, the vent hole 53, the oil return chamber 46, and the second oil return hole 52 sequentially pass through the front valve chamber 18.

  The oil discharged from the gas-liquid separator 60 flows to the front valve chamber 18 through the oil return chamber 46, passes through the second front oil return passage 43 and the first front oil return passage 42, and enters the crank chamber 2C. Flowing. Since the front valve chamber 18 is connected to the second blow-by gas passage 45 via the second oil return hole 52, the oil return chamber 46, and the vent hole 53, the pressure is equal to that of the crank chamber 2C.

  Since the vent hole 53 is arranged above the second front oil return passage 43 in the vertical direction, the oil in the front valve chamber 18 is suppressed from flowing into the second blow-by gas passage 45, and the oil to the blow-by gas Mixing of is suppressed. Further, since the vent hole 53 is disposed above the first oil return hole 51 in the vertical direction, the oil flowing from the first oil return hole 51 into the oil return chamber 46 is difficult to flow into the vent hole 53. Further, since the vent hole 53 is disposed at a portion corresponding to the upper end portion in the vertical direction of the oil return chamber 46, the oil in the oil return chamber 46 is difficult to flow into the vent hole 53. Further, since the second partition wall 48 is overhanging in the vertical direction toward the oil return chamber 46, the oil in the oil return chamber 46 is more difficult to reach the vent hole 53.

  Since the second blow-by gas passage 45 has a larger cross-sectional area in the upper part than the lower part in the cylinder axial direction, the flow speed of the blow-by gas decreases while flowing through the second blow-by gas passage 45, so that the flow of blow-by gas is reduced. The oil droplets that have been pulled and floated easily fall off the blow-by gas and become separated.

  The upper part of the second blow-by gas passage 45 is branched into a front branch portion 45A and a rear branch portion 45B, the front branch portion 45A is connected to the connection passage 55A, and the rear branch portion 45B is connected to the vent hole 53. Oil in the oil return chamber 46 is more difficult to flow from the vent hole 53 to the second blow-by gas passage 45.

  Since the upper part of the second blow-by gas passage 45 and the oil return chamber 46 are formed inside the right end wall 12 forming the bearing wall 21, the cylinder head can be reduced in size.

  Since the upper portion 48A of the second partition wall 48 extends toward one center of the camshaft 19, the front partition head 48B is subjected to the load applied to the front cylinder head 4 from the winding transmission body 19B via one of the camshafts 19. The rigidity of the cylinder head 4 is improved. Further, the upper part 48A of the second partition wall 48 has a bisector of an imaginary angle formed by an imaginary straight line obtained by extrapolating a winding transmission body 19B extending in two tangential directions from one rotating body 19A of the camshaft 19. Since it extends substantially in parallel, the rigidity of the front cylinder head 4 is improved.

  Since the oil return chamber 46 is disposed adjacent to the cooling water passage 57, the oil is heated by heat exchange between the oil passing through the oil return chamber 46 and the cooling water passing through the cooling water passage 57. Further, since the second blow-by gas passage 45 is disposed adjacent to the cooling water passage 57, the temperature of the wall surface that defines the second blow-by gas passage 45 by heat exchange with the cooling water passing through the cooling water passage 57 is increased. Condensation and freezing of moisture in the blow-by gas that is maintained at a relatively high temperature and passes through the second blow-by gas passage 45 are suppressed. Further, the cooling water passage 57 is provided below the oil return chamber 46 and on the side of the second blow-by gas passage 45, so that the cooling water passage 57, the oil return chamber 46, and the second blow-by gas passage 45 are connected to the front cylinder head. 4 is arranged efficiently at the end of 4.

  Since the oil return chamber 46 is located on the higher side of the inclined front cylinder head 4, the backflow of oil from the front valve chamber 18 to the oil return chamber 46 is suppressed. Since the front cylinder head 4 and the rear cylinder head 6 are formed in the same shape, the manufacturing cost can be reduced. Further, since the gas-liquid separator 60 is disposed in the recess between the front cylinder head 4 and the rear cylinder head 6, the overall internal combustion engine can be reduced in size.

  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. In the above embodiment, the front cylinder head 4 is provided with the second blow-by gas passage 45, the oil return chamber 46, and the like. However, the internal combustion engine 1 is disposed in the reverse direction, and the second blow-by gas passage 45 and the oil return chamber are arranged. The chamber 46 may be provided in the rear cylinder head. Further, the internal combustion engine 1 may be arranged such that the crankshaft extends in the front-rear direction, and the second blow-by gas passage 45 and the oil return chamber 46 may be provided in a cylinder head provided on the left side or the right side.

1: Internal combustion engine 2: Cylinder block 2C: Crank chamber 2D: Cylinder 3A: Oil storage chamber 4: Front cylinder head 5: Front head cover 11: Side wall 12: End wall 18: Front valve chamber 19: Camshaft 21: Bearing wall 30: Intake system 41: First blow-by gas passage 42: First front oil return passage 43: Second front oil return passage 45: Second blow-by gas passage 45A: Front branch portion 45B: Rear branch portion 46: Oil return chamber 47 : First partition wall 48: second partition wall 51: first oil return hole 52: second oil return hole 53: vent hole 55A: connection passage 60: gas-liquid separator 61A: gas inlet port 61B: first gas outlet port 61C : Second gas outlet port 61D: Oil discharge port

Claims (17)

A cylinder block having a cylinder and a crank chamber;
A cylinder head coupled to the upper end of the cylinder block in the cylinder axial direction;
A head cover coupled to an upper end of the cylinder head in the cylinder axial direction and defining a valve operating chamber and a connection passage separated from each other in cooperation with the cylinder head;
A gas inlet port connected to the connection passage, a gas outlet port connected to an intake system of an internal combustion engine, and a gas-liquid separator provided with an oil discharge port for discharging separated oil;
The cylinder block has a first blow-by gas passage and a first oil return passage extending from the crank chamber to an end face on the cylinder head side,
The cylinder head extends in a cylinder axial direction and is separated from the valve chamber by a second blow-by gas passage and a first partition that connect the first blow-by gas passage and the connection passage, and the second partition by the second partition. An oil return chamber having a first oil return hole separated from the blow-by gas passage and connected to the oil discharge port; and a second oil return passage connecting the valve operating chamber and the first oil return passage. ,
A second oil return hole that connects the oil return chamber and the valve operating chamber is formed in the first partition wall,
The second partition wall is formed with a vent hole that connects the oil return chamber and the second blow-by gas passage,
The internal combustion engine, wherein the vent hole is arranged above the second oil return hole in the vertical direction.   2. The internal combustion engine according to claim 1, wherein the second oil return hole is disposed in a portion corresponding to a lower end portion in a vertical direction of the oil return chamber.   The internal combustion engine according to claim 1, wherein the first oil return hole is disposed below the vent hole in a vertical direction.   The internal combustion engine according to any one of claims 1 to 3, wherein the vent hole is disposed at a portion corresponding to an upper end portion in a vertical direction of the oil return chamber.   5. The internal combustion engine according to claim 1, wherein the second blow-by gas passage has a wider cross-sectional area in the upper part than in the lower part in the cylinder axial direction.   The upper part in the vertical direction of the second blow-by gas passage is branched into a plurality of passages, one branched passage is connected to the connection passage, and the other branched passage is connected to the vent hole. The internal combustion engine according to any one of claims 1 to 5, wherein The cylinder head has a bearing wall that rotatably supports the camshaft,
The internal combustion engine according to any one of claims 1 to 6, wherein an upper portion of the second blow-by gas passage in the cylinder axial direction is formed inside the bearing wall.   The internal combustion engine according to claim 7, wherein the bearing wall also serves as an end wall constituting an end portion of the cylinder head in a cylinder row direction.   The internal combustion engine according to claim 7 or 8, wherein an upper portion of the oil return chamber in the cylinder axial direction is formed inside the bearing wall.   The internal combustion engine according to any one of claims 1 to 9, wherein the second partition wall is overhanging on the oil return chamber side with respect to a vertical direction.   The said 1st partition is extended in the direction orthogonal to a cylinder row | line | column direction, in order to isolate | separate a said 2nd blow-by gas passage, the said oil return chamber, and the said valve operating chamber. The internal combustion engine according to any one of 10 items. Two cylinder shafts are supported on the cylinder head,
The internal combustion engine according to any one of claims 1 to 11, wherein the second partition wall has a portion extending toward one center of the camshaft. Two cylinder shafts are supported on the cylinder head,
A chain or belt is wound around the sprocket or pulley provided at each end of the camshaft together with the sprocket or pulley provided at the end of the crankshaft.
The second partition has a portion extending in parallel with a bisector of an angle formed by a virtual straight line obtained by extrapolating the chain or belt extending in two directions from one sprocket or pulley of the camshaft. The internal combustion engine according to any one of claims 1 to 12, wherein the internal combustion engine is characterized.   The second blow-by gas passage and the oil return chamber are disposed adjacent to a cooling water passage formed in the cylinder head, according to any one of claims 1 to 13. The internal combustion engine described.   The internal combustion engine according to claim 14, wherein the cooling water passage is provided below the oil return chamber and on a side of the second blow-by gas passage. The internal combustion engine is a V-type internal combustion engine having two cylinder banks offset from each other in the cylinder row direction,
Each of the cylinder banks has the same shape of the cylinder heads reversed in the cylinder row direction,
16. The internal combustion engine according to claim 1, wherein each of the oil return chambers is formed on a side of each of the cylinder heads facing each other.   The internal combustion engine according to claim 16, wherein the gas-liquid separator is disposed between the pair of cylinder heads.

Images