Engine

Abstract

To suppress generation of emulsion.SOLUTION: An engine 10 introducing air in an intake passage into a crankcase 15 so as to ventilate blow-by gas includes an air introduction passage which communicates the intake passage with the crankcase 15, a one-way valve 60 which is attached to the crankcase 15 and restricts the flow of gas in a direction from the crankcase 15 toward the intake passage through the air introduction passage, and a communication passage 73 which guides the air discharged from the one-way valve 60 into the crankcase 15 and is extended in a direction different from the air discharge direction of the one-way valve 60.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an engine with crankcase ventilation. [Background technology]

[0002] As shown in Patent Document 1, there is known an engine equipped with a ventilation system that ventilates blow-by gases in the crankcase by introducing air from the intake passage into the crankcase. The engine ventilation system in Patent Document 1 is equipped with a one-way valve that restricts the backflow of gas from the crankcase toward the intake passage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-185181 Summary of the Invention [Problem to be solved by the invention]

[0004] Blow-by gas contains water and oil. One-way valves installed in the engine are sometimes exposed to the blow-by gas. When the temperature of the one-way valve is low, the water in the blow-by gas condenses inside or around the one-way valve, and the condensed water may mix with the oil to form an emulsion. [Means for solving the problem]

[0005] The engine that solves the above problem is an engine that introduces air from an intake passage into a crankcase to ventilate blow-by gas, and is equipped with an air inlet passage that connects the intake passage with the crankcase, a one-way valve attached to the crankcase and restricts the flow of gas from the crankcase to the intake passage through the air inlet passage, and a connecting passage that guides air discharged from the one-way valve into the interior of the crankcase, and the connecting passage extends in a direction different from the air discharge direction of the one-way valve. [Effects of the Invention]

[0006] The engine has the effect of suppressing the generation of emulsion. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram showing a schematic configuration of a first embodiment of an engine; [Figure 2] FIG. 2 is a side view of the oil pan and its vicinity of the engine. [Figure 3] 3 is a cross-sectional view showing the cross-sectional structure of the valve housing of the engine and its vicinity taken along line 3-3 in FIG. 2. [Figure 4] FIG. 6 is a cross-sectional view of a one-way valve and its vicinity in a second embodiment of the engine. DETAILED DESCRIPTION OF THE INVENTION

[0008] (First embodiment) Hereinafter, a first embodiment of the engine will be described in detail with reference to FIGS. <About the configuration of Engine 10> First, the configuration of an engine 10 will be described with reference to Figure 1. The engine 10 shown in Figure 1 is a hydrogen engine that generates power by burning hydrogen. In the case of a hydrogen engine, combustible hydrogen may be contained in blow-by gas. For this reason, hydrogen engines are required to have higher blow-by gas ventilation performance than gasoline or diesel engines.

[0009] The engine 10 includes a cylinder block 11. A plurality of cylinders 12 are formed inside the cylinder block 11. FIG. 1 shows only one of the cylinders 12. A piston 13 is housed in each cylinder 12 so that it can reciprocate freely. A combustion chamber 17 for burning hydrogen is formed above the piston 13 in each cylinder 12. An oil pan 14 for storing oil is attached to the bottom of the cylinder block 11. A crankcase 15 is formed below the cylinders 12 inside the cylinder block 11. A cylinder head 16 is attached to the top of the cylinder block 11. Individual intake ports 18 and exhaust ports 19 are formed inside the cylinder head 16 for each cylinder 12. A head cover 16A is attached to the top of the cylinder head 16. A valve train chamber 20 for accommodating a valve train is formed inside the upper part of the cylinder head 16 covered by the head cover 16A.

[0010] The engine 10 is equipped with an intake passage 21, which is a passage through which air is introduced into the combustion chamber 17, and an exhaust passage 22, which is a passage through which exhaust gas is discharged from the combustion chamber 17. An air cleaner 23 is provided in the intake passage 21 to filter dust and the like in the air. A compressor 24 is provided in the intake passage 21 downstream of the air cleaner 23. The compressor 24, together with a turbine 25 provided in the exhaust passage 22, constitutes a turbocharger. An intercooler 26 is provided in the intake passage 21 downstream of the compressor 24. The intercooler 26 is a heat exchanger for cooling air that has been heated by compression in the compressor 24. A throttle valve 27 is provided in the intake passage 21 downstream of the intercooler 26. The throttle valve 27 is a valve for adjusting the flow rate of air sent to the combustion chamber 17 through the intake passage 21. The intake passage 21 branches off for each cylinder 12 at an intake manifold 28 provided downstream of a throttle valve 27. The intake manifold 28 is connected to the combustion chamber 17 through an intake port 18.

[0011] The engine 10 is equipped with an injector 29 that injects hydrogen into the air used for combustion in the combustion chamber 17. In the case of Figure 1, the injector 29 is installed so as to inject hydrogen into the intake port 18, but the injector 29 may also be installed so as to inject hydrogen into the combustion chamber 17. The engine 10 further includes an intake valve 32 that opens and closes the intake port 18 to the combustion chamber 17, and an exhaust valve 33 that opens and closes the exhaust port 19 to the combustion chamber 17.

[0012] <About the ventilation system> The engine 10 is equipped with a ventilation system for the crankcase 15. The ventilation system has three passages, a first passage R1, a second passage R2, and a third passage R3, which connect the intake passage 21 and the crankcase 15.

[0013] The first passage R1 is a passage that connects the crankcase 15 to a portion of the intake passage 21 downstream of the throttle valve 27. The first passage R1 is composed of a blow-by gas passage 40, a first separator 41, a PCV valve 42, a first PCV hose 43, and a second separator 44. The first separator 41 and the second separator 44 are separators that separate oil mist from the blow-by gas flowing through the first passage R1. The first separator 41 is attached to the inside of the head cover 16A. The blow-by gas passage 40 is a passage that passes through the inside of the cylinder block 11 and the cylinder head 16 and connects the crankcase 15 to the first separator 41. The second separator 44 is provided in a portion of the blow-by gas passage 40 in the cylinder block 11. The first PCV hose 43 is a hose that connects the first separator 41 to the intake manifold 28. The PCV valve 42 is a valve that allows gas to flow from the inside of the crankcase 15 to the intake passage 21 through the first passage R1, while restricting gas from flowing from the intake passage 21 to the inside of the crankcase 15 through the first passage R1. The PCV valve 42 is installed at a connection portion of the first PCV hose 43 to the first separator 41.

[0014] The second passage R2 is a passage that connects the crankcase 15 to a portion of the intake passage 21 downstream of the compressor 24. In the case of FIG. 1, the second passage R2 is configured to connect the intake manifold 28 to the crankcase 15. The second passage R2 is configured by a second PCV hose 45 and a one-way valve 60. The second PCV hose 45 is a hose that connects the crankcase 15 to the intake manifold 28. The one-way valve 60 is a valve that allows air to flow from the intake passage 21 to the crankcase 15 through the second passage R2, while restricting gas flow from the crankcase 15 to the intake passage 21 through the second passage R2. In the case of the engine 10 of this embodiment, the one-way valve 60 is attached to the crankcase 15. The attachment structure of the one-way valve 60 to the crankcase 15 will be described in detail later.

[0015] The third passage R3 is a passage that connects the crankcase 15 to a portion of the intake passage 21 upstream of the compressor 24. The third passage R3 is composed of an oil return passage 47, a valve train chamber 20, a third separator 48, and a third PCV hose 49. The oil return passage 47 passes through the interior of the cylinder block 11 and the cylinder head 16 and connects the valve train chamber 20 to the crankcase 15. The oil return passage 47 functions as a passage for returning oil from the valve train chamber 20 to the oil pan 14, and also as a passage for distributing gas between the valve train chamber 20 and the crankcase 15. The third separator 48 is a separator that separates oil mist from the blow-by gas flowing through the third passage R3. The third separator 48 is installed inside the head cover 16A. The third PCV hose 49 is a hose that connects a portion of the intake passage 21 downstream of the air cleaner 23 and upstream of the compressor 24 to the third separator 48.

[0016] When the engine 10 is operating in a naturally aspirated state, the portion of the intake passage 21 downstream of the throttle valve 27 becomes negative pressure. This negative pressure causes blow-by gas in the crankcase 15 to be drawn into the intake passage 21 through the first passage R1. Air is also introduced into the crankcase 15 through the third passage R3. On the other hand, when the engine 10 is operating in a supercharged state, the portion of the intake passage 21 downstream of the compressor 24 becomes positive pressure. At this time, the positively pressurized air is introduced from the intake passage 21 into the crankcase 15 through the second passage R2. The introduced air then pushes out the blow-by gas in the crankcase 15 and releases it into the intake passage 21 through the third passage R3.

[0017] <Installation structure of one-way valve 60> In the engine 10 of this embodiment, the one-way valve 60 that restricts the gas flow direction in the second passage R2 is directly attached to the crankcase 15. Hereinafter, the mounting structure of the one-way valve 60 to the crankcase 15 will be described with reference to both FIGS. 2 and 3. FIG. 2 shows a side view of the oil pan 14 of the engine 10 and its vicinity. FIG. 3 shows a cross-sectional structure of the valve housing 50 and its vicinity taken along line 3-3 in FIG. 2. In the following description, the state of the engine 10 when the vehicle on which the engine 10 is mounted is stationary on a horizontal plane will be referred to as the state of the engine 10 when mounted on the vehicle. Furthermore, the level of engine oil in the crankcase 15 when an amount of engine oil at the upper limit of the appropriate range is poured into the engine 10 when mounted on the vehicle will be referred to as the reference oil level SO.

[0018] As shown in FIG. 2, the engine 10 includes a valve housing 50 for attaching a one-way valve 60 to the crankcase 15. The valve housing 50 is fixed to the outer wall of the oil pan 14 by bolts 51. In the case of FIG. 2, the valve housing 50 is fixed by two bolts 51. The valve housing 50 may also be fixed by one bolt 51, or by three or more bolts 51. Furthermore, the valve housing 50 may also be fixed to the crankcase 15 by a method other than the bolts 51.

[0019] As shown in FIG. 3 , the one-way valve 60 has a generally cylindrical shape with a through-hole 61 that extends from one end to the other. One end of the through-hole 61 serves as an inlet 62 for air from the intake passage 21. The other end of the through-hole 61 serves as an outlet 63 for air to the inside of the crankcase 15. The one-way valve 60 also has a flange 64 that has a larger outer diameter than other portions. In the following description, the portion of the one-way valve 60 that is closer to the inlet 62 than the flange 64 will be referred to as a front end 65. The portion of the one-way valve 60 that is closer to the outlet 63 than the flange 64 will be referred to as a rear end 66.

[0020] The one-way valve 60 is equipped with a check mechanism (not shown). The check mechanism is a mechanism that allows gas to flow from the inlet 62 to the outlet 63 through the through hole 61, while restricting gas from the outlet 63 to the inlet 62. The check mechanism can be a well-known mechanism that includes, for example, a valve body and a spring that biases the valve body.

[0021] A boss 70 is provided in the oil pan 14 at a mounting portion of the one-way valve 60 and the valve housing 50. The boss 70 has an insertion hole 71 into which the front end 65 and flange 64 of the one-way valve 60 are inserted. When the engine 10 is mounted on the vehicle, the insertion hole 71 extends downward from the outside to the inside of the crankcase 15. The one-way valve 60 is attached to the crankcase 15 with the flange 64 and front end 65 inserted into the insertion hole 71. The one-way valve 60 is inserted partway into the insertion hole 71, and a space is defined by the one-way valve 60 at the back of the insertion hole 71. In the following description, this space will be referred to as an auxiliary chamber 72. Furthermore, a connecting passage 73 is formed in the oil pan 14, connecting the interior of the crankcase 15 to the auxiliary chamber 72. Air discharged from the discharge port 63 of the one-way valve 60 is introduced into the interior of the crankcase 15 through the auxiliary chamber 72 and the connecting passage 73. The connecting passage 73 serves as a passage that guides the air discharged from the one-way valve 60 into the inside of the crankcase 15. The connecting passage 73 opens to the inner wall surface of the crankcase 15 at a portion that is located above the reference oil level SO when the engine 10 is mounted on the vehicle.

[0022] In the following description, the vertically upper side of the engine 10 when it is mounted on a vehicle will be referred to as the mounted upper side UP, and the vertically lower side will be referred to as the mounted lower side DW. Furthermore, the horizontal direction of the engine 10 when it is mounted on a vehicle in the cross section shown in Fig. 3 will be referred to as the mounted horizontal direction. Furthermore, the direction from the outside to the inside of the crankcase 15 in the mounted horizontal direction in the cross section shown in Fig. 3 will be referred to as the case inside IN, and the direction from the inside to the outside of the crankcase 15 will be referred to as the case outside OUT.

[0023] In FIG. 3 , the central axis L1 of the insertion hole 71 and the central axis L2 of the connecting passage 73 are each indicated by a dashed line. The connecting passage 73 extends in a direction different from that of the insertion hole 71. Specifically, the insertion hole 71 extends in a direction inclined with respect to the horizontal direction when mounted so that the portion inside the case (IN) is located lower (DW) than the portion outside the case (OUT) when mounted. In contrast, the connecting passage 73 extends in a direction inclined with respect to the horizontal direction when mounted so that the portion inside the case (IN) is located higher (UP) than the portion outside the case (OUT) when mounted. The one-way valve 60 is inserted into the insertion hole 71 in an orientation such that the direction of air discharge from the discharge port 63 is the same as the extension direction of the insertion hole 71. Therefore, when the one-way valve 60 is assembled, the connecting passage 73 extends in a direction different from the direction of air discharge from the one-way valve 60.

[0024] <Operation of the embodiment> The engine 10 configured as described above is configured to introduce air from the intake passage 21 into the crankcase 15 to ventilate blow-by gas. The engine 10 is provided with a second passage R2 that connects the intake passage 21 and the crankcase 15. The second passage R2 functions as an air introduction passage for introducing air into the crankcase 15 during supercharged operation. The engine 10 is also provided with a one-way valve 60 that restricts the flow of gas from the crankcase 15 toward the intake passage 21 through the second passage R2. In other words, the one-way valve 60 prevents backflow of blow-by gas into the intake passage 21 through the second passage R2.

[0025] Due to its function, the one-way valve 60 is installed in a location exposed to blow-by gas. Blow-by gas contains oil and moisture. When the temperature of the one-way valve 60 or its surroundings is low, the moisture in the blow-by gas condenses and liquefies. The condensed water may then mix with the oil, forming an emulsion. Furthermore, in a low-temperature environment, if the engine 10 is stopped with condensed water remaining inside the one-way valve 60, the remaining water may freeze while the engine 10 is stopped. The next time the engine 10 is operated, the one-way valve 60 may not operate properly until the ice melts.

[0026] In contrast, the one-way valve 60 of the engine 10 of this embodiment is attached directly to the crankcase 15. More specifically, the engine 10 includes a valve housing 50 fixed to the outer wall of the crankcase 15. The one-way valve 60 is attached to the crankcase 15 while being sandwiched between the crankcase 15 and the valve housing 50. Heat generated by combustion in the engine 10 is directly transferred to the one-way valve 60 via the crankcase 15. Therefore, even immediately after a cold start, the one-way valve 60 is quickly warmed up by the heat received from the crankcase 15. This prevents emulsion and freezing from occurring in the one-way valve 60.

[0027] When the one-way valve 60 is directly attached to the crankcase 15, the installation position and orientation of the one-way valve 60 relative to the crankcase 15 may be limited due to factors such as interference with surrounding components and ease of installation. In this embodiment, the one-way valve 60 is attached to the crankcase 15 with the discharge port 63 facing diagonally downward. The arrow F1 shown by a dotted line in FIG. 3 indicates the direction of air discharge from the discharge port 63 of the one-way valve 60 attached in this manner. If air were to be discharged directly into the crankcase 15 from the discharge port 63 of the one-way valve 60, the air would be blown directly onto the engine oil, causing ripples on the oil surface. This could result in an increased air bubble content in the engine oil. Furthermore, the blowing of air increases the amount of engine oil that becomes mist. A portion of the mist of engine oil is returned to the intake air along with the blow-by gas and burned in the combustion chamber 17, resulting in increased engine oil consumption.

[0028] In contrast, the engine 10 of this embodiment is provided with a connecting passage 73 that guides the air discharged from the one-way valve 60 into the crankcase 15. The connecting passage 73 extends in a direction different from the air discharge direction of the one-way valve 60. Specifically, the connecting passage 73 extends in a direction that increases the distance from the reference oil level SO as it extends from the outside of the case OUT to the inside of the case IN. The air discharged from the discharge port 63 of the one-way valve 60 flows into the crankcase 15 through the connecting passage 73. The solid arrow F2 in FIG. 3 indicates the direction of air discharge from the connecting passage 73 into the crankcase 15. The direction of air discharge from the connecting passage 73 into the crankcase 15 is away from the oil level. Therefore, in the engine 10 of this embodiment, the air discharged from the one-way valve 60 is prevented from being sprayed onto the engine oil.

[0029] <Effects of the embodiment> According to the engine 10 of the present embodiment described above, the following effects can be achieved. (1) The engine 10, which introduces air from the intake passage 21 into the crankcase 15 to ventilate blow-by gas, includes a second passage R2, which is an air inlet passage that connects the intake passage 21 and the crankcase 15. The engine 10 also includes a one-way valve 60 that restricts the flow of gas from the crankcase 15 to the intake passage 21 through the second passage R2. The one-way valve 60 is directly attached to the crankcase 15. More specifically, the engine 10 includes a valve housing 50 that is fixed to the outer wall of the crankcase 15. The one-way valve 60 is attached to the crankcase 15 while being sandwiched between the crankcase 15 and the valve housing 50. In this engine 10, the one-way valve 60 is warmed by heat received from the crankcase 15. This reduces the occurrence of emulsion or freezing in the one-way valve 60 due to low temperatures.

[0030] (2) The engine 10 is provided with a connecting passage 73 that guides the air discharged from the one-way valve 60 into the crankcase 15. The connecting passage 73 extends in a direction different from the direction in which the air is discharged from the one-way valve 60. Therefore, the direction in which the air is discharged into the crankcase 15 is different from the direction in which the air is discharged from the one-way valve 60. Therefore, the direction in which the air is discharged into the crankcase 15 can be set regardless of the mounting position of the one-way valve 60.

[0031] (3) An insertion hole 71 into which the one-way valve 60 is inserted is formed in the outer wall of the crankcase 15. The insertion hole 71 extends in a direction such that, when the engine 10 is mounted on the vehicle, the portion of the insertion hole 71 located inside the crankcase 15 is positioned lower than the portion of the insertion hole 71 located outside the crankcase 15. The one-way valve 60 attached to the crankcase 15 while inserted into the insertion hole 71 discharges air diagonally downward. Therefore, if air were to be discharged directly into the crankcase 15 from the one-way valve 60, the air would likely be blown onto the oil surface. In the engine 10 of this embodiment, air is introduced into the crankcase 15 via a connecting passage 73 that extends in a direction different from the direction in which the air is discharged from the one-way valve 60. Specifically, when the engine 10 is mounted on the vehicle, the connecting passage 73 extends in a direction such that the end of the connecting passage 73 that opens into the interior of the crankcase 15 is positioned higher than the opposite end. This reduces the likelihood of air being blown onto the engine oil. As a result, an increase in the air bubble rate in the engine oil and removal of the engine oil are suppressed.

[0032] (Second embodiment) Next, a second embodiment of the engine will be described in detail with reference to Fig. 4. In this embodiment, components common to the above embodiment will be denoted by the same reference numerals, and detailed description thereof will be omitted.

[0033] Fig. 4 shows a cross-sectional structure of the one-way valve 60 and its vicinity in the engine of this embodiment. The cross section shown in Fig. 4 corresponds to the cross section of the engine 10 of the first embodiment shown in Fig. 3. In the engine of this embodiment, the air discharged from the one-way valve 60 is introduced into the crankcase 15 via a curved pipe 75 installed inside the crankcase 15.

[0034] In the engine of this embodiment, a mounting hole 74 is formed in the boss 70 of the oil pan 14. The mounting hole 74 communicates with the interior of the crankcase 15 and an insertion hole 71, into which the one-way valve 60 is inserted. The mounting hole 74 is coaxial with the insertion hole 71. A curved pipe 75 is attached to the crankcase 15 while being inserted into the mounting hole 74. In the case of FIG. 4, the opening of the mounting hole 74 into the crankcase 15 is located below the reference oil level SO.

[0035] In the following description, the end of the curved pipe 75 that is inserted into the mounting hole 74 will be referred to as the base end of the curved pipe 75. The end of the curved pipe 75 opposite the base end will be referred to as the tip end of the curved pipe 75. The tip end of the curved pipe 75 extends obliquely upward with respect to the reference oil level SO and protrudes above the reference oil level SO. In the engine of this embodiment, the tip end of the curved pipe 75 forms a connecting passage 76 that extends in a direction different from the air discharge direction of the one-way valve 60.

[0036] In the engine of this embodiment configured as described above, the direction in which air is discharged into the crankcase 15 is changed by the curved pipe 75. Therefore, the engine of this embodiment also provides the same effects as those of the first embodiment.

[0037] In the engine of this embodiment, when mounted on a vehicle, the air discharge port 63 of the one-way valve 60 is located below the reference oil level SO. On the other hand, the opening of the connecting passage 76 to the inside of the crankcase 15 is located above the reference oil level SO. Therefore, even if the one-way valve 60 is installed so that the discharge port 63 is located below the reference oil level SO, it is difficult for engine oil to flow into the one-way valve 60.

[0038] (Other embodiments) The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0039] In the above embodiment, the connecting passages 73 and 76 were provided to change the direction of air discharge into the crankcase 15 from the direction of air discharge from the one-way valve 60, thereby preventing air from being blown onto the oil surface. The connecting passages 73 and 76 may be provided for other purposes. For example, the connecting passages 73 and 76 may be provided to improve the ventilation efficiency of the crankcase 15. The ventilation efficiency of the crankcase 15 varies depending on the position and direction of air discharge into the crankcase 15. When air is discharged directly into the crankcase 15 from the one-way valve 60, depending on the installation position and posture of the one-way valve 60, air may not be introduced into the crankcase 15 in a manner suitable for ventilation. Even in such cases, providing a connecting passage extending in a direction different from the direction of air discharge from the one-way valve 60 may allow air to be introduced into the crankcase 15 in a manner suitable for ventilation. In this case, the extension direction of the connecting passage may be different from that of the above embodiment.

[0040] The one-way valve 60 may be attached to the skirt portion of the cylinder block 11 that forms the outer wall of the crankcase 15. In the engine of the above embodiment, the one-way valve 60 is attached to the crankcase 15 in a state where it is sandwiched between the crankcase 15 and the valve housing 50. However, the one-way valve 60 may be attached to the crankcase 15 in a manner other than this.

[0041] The configuration of the ventilation system for the engine 10 can be modified as appropriate as long as it includes the second passage R2 provided with the one-way valve 60. For example, if ventilation of the crankcase 15 is not required during naturally aspirated operation, the first passage R1 may be omitted.

[0042] The engine 10 may be an engine other than a hydrogen engine. (Additional notes) [Appendix 1] An engine that introduces air from an intake passage into a crankcase to ventilate blow-by gas, comprising: an air inlet passage that connects the intake passage with the crankcase; a one-way valve attached to the crankcase that restricts the flow of gas from the crankcase to the intake passage through the air inlet passage; and a connecting passage that guides air discharged from the one-way valve into the inside of the crankcase, wherein the connecting passage extends in a direction different from the air discharge direction of the one-way valve.

[0043] [Appendix 2] An engine as described in Appendix 1, wherein, when the engine is mounted on a vehicle, the connecting passage extends in a direction such that the end that opens into the inside of the crankcase is positioned higher than the opposite end.

[0044] [Appendix 3] An engine as described in Appendix 2, wherein an insertion hole into which the one-way valve is inserted is formed in an outer wall of the crankcase, and when the engine is mounted on a vehicle, the insertion hole extends in a direction such that the portion of the insertion hole located inside the crankcase is positioned lower than the portion of the insertion hole located outside the crankcase.

[0045] [Appendix 4] An engine as described in any one of Appendices 1 to 3, wherein, when the engine is mounted on a vehicle, the liquid level of the engine oil inside the crankcase when an amount of engine oil that is the upper limit of the appropriate range is injected into the engine is taken as the reference oil level, and when the engine is mounted on a vehicle, the air discharge port of the one-way valve is located below the reference oil level, and the opening of the connecting passage to the inside of the crankcase is located above the reference oil level.

[0046] [Appendix 5] An engine as described in any one of Appendices 1 to 4, further comprising a valve housing fixed to an outer wall of the crankcase, and the one-way valve is attached to the crankcase in a state sandwiched between the crankcase and the valve housing. [Explanation of symbols]

[0047] 10 Engine 11 Cylinder block 12 cylinders 13 Piston 14 Oil pan 15 Crankcase 16 Cylinder head 16A Headcover 17 Combustion chamber 18 Intake port 19 Exhaust port 20 Valve train chamber 21 Intake passage 22 Exhaust passage 23 Air cleaner 24 Compressor 25 Turbine 26 Intercooler 27 Throttle valve 28 intake manifold 29 Injector 32 Intake valve 33 Exhaust valve 40 Blow-by gas passage 41 First separator 42 PCV valve 43 First PCV hose 44 Block side separator 45 Second PCV hose 46 Passage 48 Third separator 49 3rd PCV hose 50 Valve housing 51 volts 52 Insertion hole 53 Communication hole 54 Joint 60 One-way valve 61 Through hole 62 Inlet 63 Discharge port 64 Flange 65 Front end 66 Rear end 70 Boss 71 Insertion hole 72 Antechamber 73, 76 connecting road 74 mounting holes 75 curved pipe

Claims

1. An engine that introduces air from an intake passage into a crankcase to ventilate blow-by gas, an air introduction passage that communicates the intake passage with the crankcase; a one-way valve attached to the crankcase and restricting the flow of gas from the crankcase through the air introduction passage toward the intake passage; a connecting passage that guides the air discharged from the one-way valve into the crankcase; The connecting passage extends in a direction different from the air discharge direction of the one-way valve. engine.

2. When the engine is mounted on a vehicle, the connecting passage extends in a direction such that the end of the connecting passage that opens into the crankcase is positioned higher than the opposite end.

10. The engine of claim 1.

3. an insertion hole into which the one-way valve is inserted is formed in an outer wall of the crankcase; When the engine is mounted on a vehicle, the insertion hole extends in a direction such that a portion of the insertion hole located inside the crankcase is positioned lower than a portion of the insertion hole located outside the crankcase.

3. The engine of claim 2.

4. When the engine is mounted on a vehicle, the engine oil level inside the crankcase when the upper limit of the appropriate range of engine oil is poured into the engine is taken as the reference oil level, When the engine is mounted on a vehicle, the air discharge port of the one-way valve is located below the reference oil level, and the opening of the connecting passage to the inside of the crankcase is located above the reference oil level.

10. The engine of claim 1.

5. 2. The engine according to claim 1, further comprising a valve housing fixed to an outer wall of the crankcase, wherein the one-way valve is attached to the crankcase in a state sandwiched between the crankcase and the valve housing.

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