engine

Abstract

An engine (E) according to the present disclosure comprises: a crankshaft (2) that changes the reciprocating motion of a piston (3) to a rotating motion; a crank case (4) that supports the crankshaft (2); a cylinder (6) that protrudes from the crank case (4) to one side in the piston reciprocating direction; an oil pan (14) that is attached to the lower side of the crank case (4) and forms a liquid collection space (SP) for collecting oil that has lubricated a portion to be lubricated in the crank case (4); and a scavenge pump (30) that suctions oil from inside the liquid collection space (SP) and discharges the oil to an oil tank (28). A breather intake port (38a) is formed at a position facing the liquid collection space (SP) from above.

Description

engine Related Applications

[0001] This application claims priority to Japanese Patent Application No. 2023-209059, filed December 12, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to an engine used, for example, as a driving source for a vehicle.

[0003] An engine is sometimes used as a drive source for vehicles such as motorcycles (see, for example, Patent Document 1). Such engines are provided with a crankcase breather to release pressure inside the crankcase to the outside. The fluid taken into the crankcase breather is separated into gas and liquid, and the gas component is sent to the intake passage and the liquid component is sent to the oil pan.

[0004] Japanese Patent Application Laid-Open No. 2014-065465

[0005] To enhance the gas-liquid separation effect, it is better for the fluid supplied to the crankcase breather to have a low liquid content. Therefore, it is preferable to locate the breather intake port that takes in the fluid in a location where the oil is least agitated, and for example, it is not preferable to locate it in the cam chamber of the cylinder head where the camshaft rotates, or the crank chamber of the crankcase where the crankshaft rotates. Although the oil inside the oil pan below the crankcase is less agitated, it is filled with oil, making it difficult to locate a breather intake port there.

[0006] The disclosure of the present application provides an engine that can improve the gas-liquid separation effect of fluids.

[0007] The engine of the present disclosure comprises a crankshaft that converts the reciprocating motion of the piston into rotational motion, a crankcase that supports the crankshaft, a cylinder that protrudes from the crankcase to one side in the direction of the piston reciprocating motion, an oil pan attached below the crankcase and forming a liquid collection space that collects oil that has lubricated the lubricated parts inside the crankcase, and a scavenge pump that sucks oil from the liquid collection space and discharges it into an oil tank, and a breather intake port is formed in a position facing the liquid collection space from above.

[0008] According to the engine of the present disclosure, the oil collected in the oil pan is discharged by a scavenge pump, so the oil level in the oil pan does not become too high. This prevents the liquid components of the oil in the oil pan from flowing through the breather intake into the breather chamber, improving the gas-liquid separation effect of the fluid. In particular, if the breather intake is positioned facing the oil pan's liquid collection space from above, i.e., positioned high inside the oil pan, it is less susceptible to the influence of the oil level. As a result, liquid components are less likely to be drawn in through the breather intake, improving the gas-liquid separation effect of the fluid.

[0009] Any combination of at least two features disclosed in the claims and / or the specification and / or the drawings is included in the present disclosure. In particular, any combination of two or more of the claims is included in the present disclosure.

[0010] The present disclosure will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are merely for illustration and explanation purposes and should not be used to define the scope of the present disclosure. The scope of the present disclosure is defined by the accompanying claims. In the accompanying drawings, the same part numbers in multiple drawings indicate the same parts.

[0023] Figure 1 is a side view of an engine according to a first embodiment of the present disclosure. Figure 2 is a front view of the engine. Figure 3 is a bottom view of the engine as seen from below. Figure 4 is a bottom view showing an enlarged view of section IV in Figure 3. Figure 5 is a perspective view of a breather chamber of the engine. Figure 6 is a perspective view showing a state in which a cover member and a seal member have been removed from the breather chamber. Figure 7 is a perspective view showing a state in which the cover member has been removed from the breather chamber. Figure 8 is a rear view of the cover member. Figure 9 is a schematic view showing the flow of fluid in the breather structure of the engine.

[0011] A preferred embodiment of the present disclosure will now be described with reference to Figures 1 to 9. The engine E of this embodiment is a reciprocating engine, and is used, for example, in an airplane in which a propeller is located at the tip of the fuselage. In this case, the engine E is housed within the fuselage, and engine power is transmitted to the propeller. The use of the engine E is not limited to this, and it can also be used as a drive source for a ship, or for vehicles such as motorcycles and automobiles.

[0012] In the following description, the "width direction WD" refers to the direction in which the crankshaft 2 of the engine E extends, i.e., the axial direction of the crankshaft 2. In the width direction WD, the direction toward the width center is referred to as the "width inner side," and the direction away from the width center is referred to as the "width outer side." The "reciprocating direction VD" refers to the direction of reciprocating motion of the piston of the engine E. The direction perpendicular to both the "width direction WD" and the "reciprocating direction VD" is referred to as the "perpendicular direction PD."

[0013] The engine E of this embodiment is a six-cylinder engine with six cylinders aligned in the direction of the crankshaft 2. However, the number of cylinders is not limited to this and may be, for example, four. Furthermore, although the engine E of this embodiment is a gasoline engine, the fuel is not limited to gasoline. The crankshaft 2 converts the reciprocating motion of the pistons 3 into rotational motion.

[0014] The engine E has a crankcase 4 that supports a crankshaft 2, cylinders 6 that protrude from the crankcase 4 in one direction in the reciprocating direction VD, and a cylinder head 8 that is connected to the protruding ends of the cylinders 6. The crankshaft 2 is disposed in a crank chamber 5 inside the crankcase 4. In the following description, the direction in which the cylinders 6 protrude from the crankcase 4 in the reciprocating direction VD is referred to as "upward," and the opposite direction is referred to as "downward."

[0015] The crankcase 4 is divided into two parts, a lower crankcase 4a and an upper crankcase 4b. In this embodiment, the upper crankcase 4b and the cylinder 6 are integrally formed by molding. However, the upper crankcase 4b and the cylinder 6 may be separate bodies. In the following description, the integrated upper crankcase 4b and the cylinder 6 are referred to as a cylinder block 10.

[0016] The engine E further has a head cover 12 connected to the upper end of the cylinder head 8. The cylinder head 8 and the cylinder head cover 12 form a cam chamber. A valve mechanism that opens and closes the intake and exhaust valves in conjunction with the rotation of the crankshaft 2 is disposed in the cam chamber.

[0017] The engine E further has an oil pan 14 connected to the lower end of the crankcase 4. The oil pan 14 stores engine oil that lubricates parts of the engine E that need to be lubricated. In other words, the oil pan 14 has a liquid collection space SP that collects the oil that has lubricated the parts of the engine E that need to be lubricated.

[0018] In this embodiment, the upper crankcase 4b constitutes a first case half that is connected to the cylinder 6. On the other hand, the lower crankcase 4a constitutes a second case half that is connected to the oil pan 14.

[0019] An intake port 16 opens on one side (right side in FIG. 1) of the cylinder head 8 in the orthogonal direction PD, and an exhaust port 18 opens on the other side (left side in FIG. 1) in the orthogonal direction PD. In the following description, the intake port side in the orthogonal direction PD will be simply referred to as the "intake side," and the exhaust port side will be simply referred to as the "exhaust side."

[0020] The intake port 16 and the exhaust port 18 are passages formed inside the cylinder head 8. The upstream end of the intake port 16 opens to one side of the cylinder head 8 in the orthogonal direction PD, and the downstream end opens to a combustion chamber 20 inside the cylinder 6. The upstream end of the exhaust port 18 opens to the combustion chamber 20 inside the cylinder 6, and the downstream end opens to the front of the other side of the cylinder head 8 in the orthogonal direction PD. An intake port 16 is formed for each cylinder. Similarly, an exhaust port 18 is formed for each cylinder.

[0021] External air is supplied as intake air from the intake port 16 to the combustion chamber 20, and fuel is injected into the combustion chamber 20 from the injector 22 to form a fuel-air mixture. The mixture in the combustion chamber 20 is ignited by the spark plug 24 and burns. Exhaust gas after combustion is discharged to the outside of the engine from the exhaust port 18.

[0022] 2 is a front view of the engine E as seen from the intake side in the orthogonal direction PD. As shown in the figure, an output shaft 25 and a reduction mechanism 26 are provided on one side of the engine E in the width direction WD (the right side in FIG. 2). The rotational force of the crankshaft 2 is reduced in speed by the reduction mechanism 26 and transmitted to the output shaft 25. An aircraft propeller, a vehicle wheel, a turbine rotor blade, a compressor impeller, etc. are connected to the output shaft 25 directly or via a power transmission member.

[0023] The engine E of the present disclosure is a dry sump lubrication engine having a scavenge pump 30 that draws oil from the oil collection space SP of the oil pan 14 and discharges it into the oil tank 28.

[0024] In this embodiment, the oil tank 28 is provided outside the engine E, i.e., separated from the engine E. The oil discharged from the scavenge pump 30 is stored in the oil tank 28 and then pressurized by the feed pump 32 to lubricate the lubricated parts of the engine E. After lubricating the lubricated parts, the oil is returned to the oil pan 14 via the vertical passage 27 (FIG. 3). The vertical passage 27 is a passage that connects the crank chamber 5 and the oil pan 14.

[0025] In this embodiment, the oil pan 14 has a bottom wall 14a that forms the deepest part, and an inclined wall 14b that extends horizontally from the bottom wall 14a, and in this embodiment, slopes upward as it moves away from the bottom wall 14a in the engine width direction WD.

[0026] In this embodiment, the scavenge pump 30 is disposed inside the oil pan 14. More specifically, the scavenge pump 30 is disposed in the deepest part of the oil pan 14. The scavenge pump 30 sucks oil from the liquid collection space SP of the oil pan 14 and discharges it to the outside of the liquid collection space SP. Therefore, the oil level does not rise in the oil pan 14, and a large amount of gaseous components of the oil exists in the liquid collection space SP.

[0027] In this embodiment, the scavenge pump 30 is driven in conjunction with the rotation of the crankshaft 2. More specifically, the rotational force of the crankshaft 2 is transmitted to the scavenge pump 30 by a power transmission member 34 such as a drive chain.

[0028] In this embodiment, the feed pump 32 is also disposed within the oil pan 14. Specifically, the feed pump 32 is disposed at the deepest portion of the oil pan 14, on the other side (left side in FIG. 2 ) of the oil pan 14 in the width direction WD of the engine E. The scavenge pump 30 and the feed pump 32 are disposed side by side in the width direction WD of the engine.

[0029] In this embodiment, the feed pump 32 is also driven in conjunction with the rotation of the crankshaft 2. More specifically, the rotational force of the crankshaft 2 is transmitted to the feed pump 32 by a power transmission member 34 such as a drive chain.

[0030] In this embodiment, the rotational force of the crankshaft 2 is transmitted to both the scavenge pump 30 and the feed pump 32 by a common power transmission member 34. Specifically, the rotating shaft 30a of the scavenge pump 30 and the rotating shaft 32a of the feed pump 32 are arranged coaxially, and the two rotating shafts 30a, 32a are connected to each other. The power transmission member 34 is hung on the rotating shaft 32a of the feed pump 32, and the rotational force of the crankshaft 2 is transmitted via the power transmission member 34 to the rotating shaft 32a of the feed pump 32 and to the rotating shaft 30a of the scavenge pump 30 connected thereto.

[0031] When the engine E starts, the scavenge pump 30 and feed pump 32 are driven in conjunction with the rotation of the crankshaft 2. The feed pump 32 pumps oil stored in the oil tank 28 to the parts of the engine E that need to be lubricated. After lubricating the parts, the oil is returned to the oil pan 14 via the vertical passage 27. The oil in the liquid collection space SP of the oil pan 14 is recovered by the scavenge pump 30, cooled in the oil cooler 35, and then supplied to the oil tank 28.

[0032] Next, we will explain the breather structure 36 of the crankcase 4 of the engine E of this embodiment. The pressure inside the crankcase 4 is higher than the outside air due to blow-by gas and oil vapor. The breather structure 36 of the crankcase 4 is provided to release this pressure, i.e., the fluid inside the engine, to the outside.

[0033] The breather structure 36 has a breather inlet passage 38, a breather chamber 40, a breather outlet passage 42, and a return passage 44. Fluid F inside the crankcase 4 is taken in through the breather inlet passage 38 and flows into the breather chamber 40. The fluid F is separated into a gas component Fg and a liquid component Fl in the breather chamber 40. The gas component Fg is sent to the intake system of the engine E through the breather outlet passage 42 and supplied to the combustion chamber 20 (FIG. 1) together with the intake air. The liquid component Fl is returned to the inside of the crankcase 4 through the return passage 44. This will be described in detail below.

[0034] The breather introduction passage 38 in this embodiment is an internal passage formed inside the crankcase 4. Specifically, the breather introduction passage 38 is formed near the wall surface on the intake side of the crankcase 4 in the orthogonal direction PD. More specifically, the breather introduction passage 38 is formed on one side (the right side in FIG. 2 ) of the wall surface on the intake side of the crankcase 4 in the engine width direction WD.

[0035] The breather introduction passage 38 extends in the vertical direction, with a breather intake port 38 a at the lower end opening into the liquid collection space SP of the oil pan 14 and a breather outlet port 38 b at the upper end opening into the breather chamber 40 .

[0036] The breather intake 38a is disposed at a position facing from above the liquid collection space SP of the oil pan 14. In terms of the vertical direction, the breather intake 38a is disposed at a position higher than the intake port 30b of the scavenge pump 30. The breather intake 38a is also formed in a portion of the crankcase 4 above a mating surface 45 where the crankcase 4 meets the oil pan 14.

[0037] In detail, the breather intake port 38a is formed in the lower crankcase 4a of the crankcase 4, and is arranged inside the mating surface 45, i.e., on the liquid collection space SP side, as shown in FIG. 3 when the crankcase 4 is viewed from below.

[0038] 2, the breather inlet 38a is disposed to face the inclined wall 14b of the oil pan 14 in the engine width direction WD. In other words, the breather inlet 38a is disposed above the inclined wall 14b of the oil pan 14. The breather inlet 38a is also disposed on one side in the engine width direction WD of the scavenge pump 30. In this embodiment, the breather inlet 38a is disposed closer to the wall surface of the oil pan 14 on one side in the engine width direction WD.

[0039] As shown in Figure 4, a standing wall 46 is provided around the breather intake port 38a at the lower end of the crankcase 4. The standing wall 46 prevents oil from flowing toward the breather intake port 38a. In this embodiment, the standing wall 46 is formed integrally with the crankcase 4 by molding. The standing wall 46 extends in the axial direction of the crankshaft 2, i.e., in a direction VD intersecting the engine width direction WD.

[0040] The standing wall 46 is disposed between the vertical passage 45 and the breather inlet 38a. In this embodiment, the wall of the crankcase 4 is provided on the intake side of the breather inlet 38a in the orthogonal direction PD and on one side in the engine width direction WD (the right side in FIG. 4 ) of the breather inlet 38a. The standing wall 46 is provided on the exhaust side of the breather inlet 38a in the orthogonal direction PD and on the other side in the engine width direction WD (the left side in FIG. 4 ). In other words, the breather inlet 38a is surrounded almost entirely by the wall of the crankcase 4 and the standing wall 46.

[0041] As shown in Figure 2, a breather chamber 40 is formed in the upper crankcase 4b of the crankcase 4. More specifically, the breather chamber 40 is provided on the intake port side of the crankcase 4 in the orthogonal direction PD. Fluid taken in through the breather inlet 38a is supplied to the breather chamber 40. The breather chamber 40 has multiple chambers, and gas and liquid separation is achieved by the fluid repeatedly flowing in and out of the chambers.

[0042] In this embodiment, the breather chamber 40 is formed by a recess 48 formed in the crankcase 4 and a cover member 50 attached to the crankcase 4. In detail, as shown in FIG. 5, the cover member 50 is detachably attached to the crankcase 4 by a plurality of bolts 54 via a seal member 52 (FIG. 7). The seal member 52 is, for example, a gasket made of graphite. However, the seal member 52 is not limited to this.

[0043] As shown in Fig. 9, the breather chamber 40 of this embodiment has four chambers 61, 62, 63, and 64 separated by a plurality of partition walls 56. The structure of each chamber 61, 62, 63, and 64 of the breather chamber 40 of this embodiment will be described using Figs. 6 to 9. Fig. 6 shows a state in which the cover member 50 and the seal member 52 have been removed, Fig. 7 shows a state in which only the cover member 50 has been removed, and Fig. 8 shows the back surface of the cover member 50. Fig. 9 is a perspective view showing the flow of fluid F inside the breather chamber 40 in a simplified manner.

[0044] 6 , the breather chamber 40 is formed with a first partition wall 56a that partitions the internal space 48a of the recess 48. The first partition wall 56a is a wall that extends from the upper end to the lower end of the recess 48 of the breather chamber 40 in the up-down direction VD and divides the internal space 48a of the recess 48 in the engine width direction WD. In the following description, of the portions of the internal space 48a of the recess 48 partitioned by the first partition wall 56a, one side in the engine width direction WD will be referred to as a first portion 48a1, and the other side will be referred to as a second portion 48a2.

[0045] Additionally, a second partition wall 56b that divides the first portion 48a1 into upper and lower portions is formed in the recess 48 of the breather chamber 40. The second partition wall 56b is a wall that extends in the engine width direction WD from the first partition wall 56a to the outer wall of the recess 48, and divides the first portion 48a1 in the up-down direction VD. In the following description, of the portions of the first portion 48a1 divided by the second partition wall 56b, the upper portion will be referred to as a third portion 48a3, and the lower portion will be referred to as a fourth portion 48a4.

[0046] As shown in Figure 7, a gasket 52, which is a type of sealing member, is interposed between the end face of the outer peripheral wall of the recess 48 of the breather chamber 40, the end face of the first partition wall 56a, and the end face of the second partition wall 56b. In this embodiment, the sealing member 52 closes the third portion 48a3 of the internal space 48a of the recess 48 from the outside, i.e., from the intake side in the orthogonal direction PD. In other words, the portion of the sealing member 52 that closes the third portion 48a3 from the outside constitutes the third partition wall 56c. In this way, in this embodiment, one of the partition walls 56 is constituted by the sealing member 52.

[0047] As shown in FIG. 8, a fourth partition wall 56d is formed in a portion of the rear surface of the cover member 50 corresponding to the first partition wall 56a, and a fifth partition wall 56e is formed in a portion of the rear surface of the cover member 50 corresponding to the second partition wall 56b.

[0048] The fourth partition 56d divides the internal space 50a of the cover member 50 into a first portion 50a1 on one side (left side in FIG. 8) in the engine width direction WD and a second portion 50a2 on the other side (right side in FIG. 8). The fifth partition 56e divides the first portion 50a1 of the internal space 50a of the cover member 50 into an upper third portion 50a3 and a lower fourth portion 50a4.

[0049] A gas outlet 58 is formed in the cover member 50 to discharge gas components in the breather chamber 54 to the outside. In this embodiment, the gas outlet 58 is provided slightly below the vertical middle of the cover member 50. The breather discharge passage 42 (FIG. 2) is connected to the gas outlet 58.

[0050] A baffle plate 60 is formed on the inner surface, i.e., the back surface, of the cover member 50. The baffle plate 60 protrudes from the inner surface of the cover member 50 toward the inside of the breather chamber 40, and covers at least a portion of the circumferential direction of the gas outlet 58. In this embodiment, the baffle plate 60 has an arc shape, and covers an upper part of the gas outlet 58.

[0051] As shown in FIG. 9, when the cover member 50 is attached to the crankcase 4, the second portion 48a2 of the internal space 48a of the recess 48 and the second portion 50a2 of the internal space 50a of the cover member 50 are in communication with each other.

[0052] Similarly, with the cover member 50 attached to the crankcase 4, the third portion 48a3 of the internal space 48a of the recess 48 and the third portion 50a3 of the internal space 50a of the cover member 50 are in communication with each other. However, the third portion 48a3 of the internal space 48a of the recess 48 and the third portion 50a3 of the internal space 50a of the cover member 50 are partitioned by a third partition wall 56c of the seal member 52.

[0053] Furthermore, with the cover member 50 attached to the crankcase 4, the fourth portion 48a4 of the internal space 48a of the recess 48 and the fourth portion 50a4 of the internal space 50a of the cover member 50 are in communication with each other.

[0054] In this way, the fourth portion 48a4 of the internal space 48a of the recess 48 and the fourth portion 50a4 of the internal space 50a of the cover member 50 form a first chamber 61 of the breather chamber 40. The third portion 50a3 of the internal space 50a of the cover member 50 forms a second chamber 62 of the breather chamber 40, and the third portion 48a3 of the internal space 48a of the recess 48 forms a third chamber 63 of the breather chamber 40. The second portion 48a2 of the internal space 48a of the recess 48 and the second portion 50a2 of the internal space 50a of the cover member 50 form a fourth chamber 64 of the breather chamber 40.

[0055] Fluid flows through the first chamber 61, the second chamber 62, the third chamber 63, and the fourth chamber 64 in this order. Adjacent chambers in the flow direction are connected by a communication hole 70 formed in the partition wall 56. A breather outlet 38b of the breather introduction passage 38 opens at the exhaust side portion of the bottom wall of the first chamber 61 in the orthogonal direction PD. As shown in FIG. 8, a first communication hole 71 is formed in the fifth partition wall 56e of the cover member 50. The first chamber 61 and the second chamber 62 in FIG. 9 are connected via the first communication hole 71.

[0056] As shown in Fig. 7 , a second communication hole 72 is formed in the third partition wall 56c of the seal member 52. The second chamber 62 and the third chamber 63 in Fig. 9 are in communication with each other via the second communication hole 72. As shown in Fig. 6 , a third communication hole 73 is formed in the portion of the first partition wall 56a that constitutes the third chamber 63. The third chamber 63 and the fourth chamber 64 in Fig. 9 are in communication with each other via the third communication hole 73.

[0057] Next, a description will be given of the flow of the fluid F in the breather chamber 40 of this embodiment. The fluid F flows from the breather outlet 38b of the breather introduction passage 38 into the first chamber 61. After flowing through the first chamber 61 toward the intake side in the orthogonal direction PD, the fluid F changes direction and flows upward, and then flows through the first communication hole 71 into the second chamber 62.

[0058] The fluid F that has flowed into the second chamber 62 flows within the second chamber 62 toward the exhaust side in the orthogonal direction PD and flows into the third chamber 63 through the second communication hole 72. The fluid F that has flowed into the third chamber 63 flows within the third chamber 62 toward the exhaust side in the orthogonal direction PD, then changes direction to flow in the width direction WD and flows into the fourth chamber 64 through the third communication hole 73. The fluid F that has flowed into the fourth chamber 64 changes direction to flow downward from the width direction WD.

[0059] In this way, by repeatedly flowing in and out of each chamber 61, 62, 63, and 64 while changing its flow direction, the fluid F collides with the partition wall 56 and expands and contracts, promoting gas-liquid separation. In the fourth chamber 64, the gas component Fg of the separated fluid F is sent from the gas outlet 58 through the breather outlet passage 42 to the intake system of the engine E. Meanwhile, the liquid component Fl of the separated fluid F is returned to the oil pan 14 through the return passage 44. At this time, the baffle plate 60 above the gas outlet 58 prevents the liquid component Fl from flowing into the gas outlet 58.

[0060] An inlet 44a of the return passage 44 opens to the other side in the engine width direction WD of the bottom wall of the fourth chamber 64. The return passage 44 extends downward from the breather chamber 40, and as shown in Figure 2, an outlet, or oil return port 44b, opens to the oil pan 14. The liquid component Fl of the fluid F passes through the return passage 44 and is returned to the oil pan 14.

[0061] The return passage 44 of this embodiment is an internal passage formed inside the crankcase 4, similar to the breather introduction passage 38. The return passage 44 extends in the vertical direction, and an oil return port 44b at the lower end thereof opens into the oil collection space SP of the oil pan 14.

[0062] The oil return port 44b opens at a position in the liquid collection space SP closer to the suction port 30b of the scavenge pump 30 than the breather intake port 38a. In this embodiment, a portion (lower end) of the return passage 44 is formed in the wall of the oil pan 14 and extends downward to near the suction port 30b of the scavenge pump 30. In this embodiment, the oil return port 44b opens toward the suction port 30b of the scavenge pump 30.

[0063] According to the above configuration, the oil collected in the oil pan 14 is discharged by the scavenge pump 30, so the oil level in the oil pan 14 does not become too high. This prevents the liquid components of the oil in the oil pan 14 from flowing from the breather intake 38a toward the breather chamber 40, improving the gas-liquid separation effect of the fluid F. In particular, because the breather intake 38a is located in a position facing the liquid collection space SP of the oil pan 14 from above, i.e., at a high position inside the oil pan 14, it is less susceptible to the influence of the oil liquid level. As a result, it becomes more difficult for liquid components to be taken in through the breather intake 38a, improving the gas-liquid separation effect of the fluid F.

[0064] In this embodiment, the breather intake 38a is formed at a higher position than the suction port 30b of the scavenge pump 30. With this configuration, the breather intake 38a can be easily positioned above the oil surface by suction from the scavenge pump 30. This prevents oil from flowing from the breather intake 38a toward the breather chamber 40. As a result, the gas-liquid separation effect of the fluid F is improved.

[0065] In this embodiment, the breather intake 38a is formed in a position above the mating surface 45 of the crankcase 4 with the oil pan 14. This configuration makes it easy to position the breather intake 38a above the oil surface. This prevents oil from flowing from the breather intake 38a toward the breather chamber 40 even if the engine position changes. As a result, the gas-liquid separation effect of the fluid F is improved.

[0066] In this embodiment, the breather intake 38a is disposed closer to the axial direction of the crankshaft 2, i.e., closer to the wall surface of the oil pan 14 in the engine width direction WD, than the scavenge pump 30. This configuration makes it easier to separate the scavenge pump 30 from the breather intake 38a, and prevents oil droplets generated during suction from entering the breather intake 38a. As a result, the gas-liquid separation effect of the fluid F is improved.

[0067] In this embodiment, the oil pan 14 has a bottom wall 14a that forms the deepest portion, and an inclined wall 14b that extends upward as it moves away from the bottom wall 14a in the horizontal direction, and the breather intake 38a is located above the inclined wall 14b. With this configuration, oil is less likely to accumulate in the inclined wall 14b, which prevents oil from flowing from the breather intake 38a toward the breather chamber 40. As a result, the gas-liquid separation effect of the fluid F is improved.

[0068] 3, a vertical wall 46 is provided to prevent oil from flowing toward the breather intake 38a. This configuration prevents oil from flowing from the breather intake 38a toward the breather chamber 40. As a result, the gas-liquid separation effect of the fluid F is improved.

[0069] In this embodiment, the standing wall 46 extends in the axial direction of the crankshaft 2, i.e., in a direction intersecting the engine width direction WD. With this configuration, even if oil in the oil pan 14 moves in the axial direction of the crankshaft 2 due to a change in posture, the standing wall 46 can prevent the oil from entering the breather intake port 38a. As a result, the gas-liquid separation effect of the fluid F is improved.

[0070] In this embodiment, the standing wall 46 is disposed between the vertical passage 27, which communicates with the crank chamber 5, and the breather intake port 38a. With this configuration, the standing wall 46 can prevent oil flowing downward through the vertical passage 27 from entering the breather intake port 38a. As a result, the gas-liquid separation effect of the fluid F is improved.

[0071] In this embodiment, the breather chamber 40 is provided on the intake port side of the crankcase 2 in the orthogonal direction PD, and the breather inlet 38a is disposed closer to the wall surface on the intake port side in the orthogonal direction PD. With this configuration, the breather chamber 40 from the breather inlet 38a can be disposed on the intake side, where the temperature is relatively low, and the passage from the breather inlet 38a to the breather chamber 40 can be shortened.

[0072] In this embodiment, a breather intake port 38a is formed in the lower crankcase 4a, and a breather chamber 40 is formed in the upper crankcase 4b. With this configuration, the breather introduction passage 38 extending from the lower crankcase 4a to the upper crankcase 4b is formed long, and gas and liquid fluid are separated even within the breather introduction passage 38. As a result, the gas-liquid separation effect is improved. In addition, because the breather chamber 40 is located away from the oil pan 14, it can also be used when the attitude of the engine E changes and the oil level tilts.

[0073] In this embodiment, the breather chamber 40 is formed by a recess 48 formed in the crankcase 4 and a cover member 50 attached to the crankcase 4. According to this configuration, the volume of the breather chamber 40 can be adjusted by changing the shape of the cover member 50.

[0074] In the present embodiment, the cover member 50 is formed with a gas outlet 58 that discharges the gas component Fg in the breather chamber 40 to the outside, and a baffle plate 60 that covers at least a portion of the circumferential direction of the gas outlet 58 shown in Fig. 8 is formed on the inner surface of the cover member 50. With this configuration, the liquid component Fl of the fluid F that has been gas-liquid separated in the breather chamber 40 can be prevented from flowing toward the gas outlet 58.

[0075] 5 is attached to the crankcase 4 via a seal member 52, and the breather chamber 40 has partition walls 56 that divide the breather chamber 40 into a plurality of chambers 61 to 64 and a communication hole 70 formed in the partition walls 56, with at least one of the partition walls 56 being formed with the seal member 52. With this configuration, the seal member 52 can be used as the partition walls 56, so the number of partition walls 56 provided in the crankcase 4 can be reduced, simplifying the structure.

[0076] In the present embodiment, the oil return port 44b, which returns the liquid component Fl in the breather chamber 40 to the inside of the oil pan 14, opens at a position closer to the suction port 30b of the scavenge pump 30 than the breather intake port 38a. With this configuration, the liquid component Fl led out of the oil return port 44b is sucked through the suction port 30b of the scavenge pump 30, so that the liquid in the oil pan 14 can be efficiently discharged.

[0077] The engine of the present disclosure is preferably mounted on mobile objects such as aircraft, vehicles, etc. The engine of the present disclosure is also preferably mounted on off-road vehicles such as four-wheel buggies (all-terrain vehicles), utility vehicles, and recreational vehicles.

[0078] In this embodiment, the breather introduction passage 38 is an internal passage, but it may be an external passage, i.e., a separate pipe, as long as the breather intake port 38a is formed in a position facing the liquid collection space SP from above. In the case of an external passage, one end of the pipe is disposed in a position facing the liquid collection space SP from above, and the other end passes outside the engine and communicates with the breather chamber 40.

[0079] The present disclosure is not limited to the above embodiments, and various additions, modifications, or deletions are possible without departing from the spirit and scope of the present disclosure. For example, the engine E of the above embodiment can also be applied to saddle-type vehicles such as motorcycles, tricycles, and four-wheeled buggies (all-terrain vehicles). The engine E may be used in an outboard motor or as a propulsion source for aircraft. Additionally, the engine E may be used as a propulsion source for four-wheeled vehicles or small personal watercraft. The number of cylinders is not limited to six, and may be less than six, or seven or more. The engine E may be provided with a supercharger such as a turbocharger or a supercharger. Therefore, such configurations are also included within the scope of the present disclosure.

[0080] DESCRIPTION OF SYMBOLS 2 Crankshaft 3 Piston 4 Crankcase 4a Second case half (lower crankcase) 4b First case half (upper crankcase) 5 Crank chamber 6 Cylinder 14 Oil pan 14a Bottom wall (deepest part) 14b Inclined wall 16 Intake port 18 Exhaust port 27 Vertical passage 28 Oil tank 30 Scavenge pump 30b Scavenge pump suction port 38a Breather intake port 40 Breather chamber 45 Mating surface between crankcase and oil pan 46 Standing wall 48 Recess 50 Cover member 52 Seal member 56 Partition wall 58 Gas outlet 60 Baffle plate 61-64 Chamber 70 Communication hole E Engine SP Liquid collection space

Claims

1. An engine comprising: a crankshaft that converts the reciprocating motion of a piston into rotational motion; a crankcase that supports said crankshaft; a cylinder that protrudes from said crankcase to one side in the direction of piston reciprocation; an oil pan attached below said crankcase and forming a liquid collection space that collects oil that has lubricated lubricated parts inside the crankcase; and a scavenge pump that sucks oil from within said liquid collection space and discharges it into an oil tank, wherein a breather intake is formed in a position facing said liquid collection space from above.

2. An engine according to claim 1, wherein the breather intake is formed at a position higher than the suction port of the scavenge pump.

3. An engine as claimed in claim 1 or 2, wherein the breather intake is formed in a position above the joint surface of the crankcase with the oil pan.

4. An engine according to any one of claims 1 to 3, wherein the breather intake is disposed closer to the wall surface of the oil pan in the axial direction of the crankshaft than the scavenge pump.

5. An engine as claimed in any one of claims 1 to 4, wherein the oil pan has a bottom wall constituting the deepest part and an inclined wall extending upward as it moves away from the bottom wall in the horizontal direction, and the breather intake is positioned so as to face the inclined wall.

6. An engine according to any one of claims 1 to 5, further comprising a vertical wall for preventing oil from flowing toward the breather intake port.

7. An engine according to claim 6, wherein said standing wall extends in a direction intersecting with the axial direction of said crankshaft.

8. An engine according to claim 6 or 7, wherein the upright wall is disposed between the breather intake and an upper and lower passage communicating with a crank chamber in which the crankshaft is disposed.

9. An engine as claimed in any one of claims 1 to 8, wherein an intake port is arranged on one side of a perpendicular direction perpendicular to both the axial direction and the vertical direction of the crankshaft, and an exhaust port is arranged on the other side, a breather chamber to which fluid taken in from the breather intake is supplied is provided on the intake port side of the crankcase in the perpendicular direction, and the breather intake is arranged closer to the wall on the intake port side in relation to the perpendicular direction.

10. An engine as claimed in any one of claims 1 to 9, wherein the crankcase has a first case half to which the cylinder is connected and a second case half to which the oil pan is connected, the breather intake port is formed in the second case half, and a breather chamber to which fluid taken in from the breather intake port is supplied is formed in the first case half.

11. An engine as claimed in any one of claims 1 to 10, wherein a breather chamber is formed in the crankcase to which fluid taken in from the breather intake is supplied, and the breather chamber is formed by a recess formed in the crankcase and a cover member attached to the crankcase.

12. An engine as described in claim 11, wherein the cover member is formed with a gas outlet for discharging gas components in the breather chamber to the outside, and a baffle plate is formed on the inner surface of the cover member to cover at least a portion of the circumferential direction of the gas outlet.

13. An engine as claimed in claim 11 or 12, wherein the cover member is attached to the crankcase via a sealing member, the breather chamber has partitions which divide the breather chamber into a plurality of chambers and communication holes formed in the partitions, and at least one of the partitions is constituted by the sealing member.

14. An engine as claimed in any one of claims 1 to 13, wherein a breather chamber is formed in the crankcase to which fluid taken in from the breather intake is supplied, and an oil return port which returns the liquid components in the breather chamber to the inside of the oil pan opens at a position closer to the suction port of the scavenge pump than the breather intake port.

15. A moving body comprising an engine having a crankshaft that converts the reciprocating motion of a piston into rotational motion, a crankcase that supports the crankshaft, a cylinder that protrudes from the crankcase to one side in the direction of the piston reciprocating motion, an oil pan attached below the crankcase to form a liquid collection space that collects oil that has lubricated lubricated parts inside the crankcase, and a scavenge pump that sucks oil from within the liquid collection space and discharges it into an oil tank, and in which a breather intake is formed in a position facing the liquid collection space from above.

16. A vehicle according to claim 15, which is an off-road vehicle.

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