JP2006194108A - Internal combustion engine equipped with dry sump type lubricating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To promote returning of lubricating oil to a crank chamber through a return oil passage by using the state that a crank chamber is decompressed by suction of a scavenging pump. <P>SOLUTION: A dry sump type lubricating device of an internal combustion engine E is equipped with a feed pump 32, a scavenging pump 34 and an outflow passage through which lubricating oil and air in the valve gear chamber 20 flow outside. The outflow passage is formed only by a return oil passage 44 which is the only communication passage for communicating between the valve gear chamber 20 and the crank chamber 10. The lubricating oil in the valve gear chamber 20 and gas for breathing air including blowby gas led in the valve gear chamber 20 through the breather passage 52 are led to the crank chamber 10 through the return oil passage 44 only. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an internal combustion engine including a dry sump type lubrication device including a scavenging pump that collects lubricating oil that is supplied by a feed pump and lubricates each lubricating portion of the internal combustion engine.

As this type of internal combustion engine, for example, in a dry sump type engine disclosed in Patent Document 1, lubricating oil stored in an oil tank is pumped to an engine body by an oil supply pump to lubricate each part of the lubricating system, and then to an oil pan. Fall. The lubricating oil collected in the oil pan is sucked by the discharge pump together with the blow-by gas leaking into the crank chamber from between the piston and the cylinder, and sent to the oil tank. Further, the crank chamber is depressurized by the suction force of the discharge pump, whereby fresh air is introduced from the intake pipe into the cylinder head through the fresh air passage, and further flows into the crank chamber from the inside of the cylinder head. The blow-by gas is gas-liquid separated in the oil tank, and then returns to the intake pipe through the return passage.
JP-A-8-240113

  Normally, the lubricating oil supplied to each part of the lubricating system in the cylinder head returns to the crank chamber through a return oil passage that connects the inside of the cylinder head and the crank chamber. Further, as in the prior art, fresh air introduced into the cylinder head flows into the crank chamber through a breather passage that connects the inside of the cylinder head and the crank chamber.

  In the dry sump engine, the crank chamber is depressurized by suction of the discharge pump, so that the flow of fresh air into the crank chamber through the breather passage is promoted, while the lubricating oil flowing through the return oil passage is Since the lubricating oil is liquid, there is a large proportion of the oil flowing along the wall of the return oil passage and flowing into the crank chamber. Therefore, the contribution of the reduced pressure in the crank chamber to the promotion of the return of the lubricating oil to the crank chamber was small. For this reason, when the return of the lubricating oil from the cylinder head to the crank chamber is insufficient, the required amount of the lubricating oil has to be increased.

  The present invention has been made in view of such circumstances, and the invention according to claims 1 and 2 utilizes the fact that the crank chamber is depressurized by suction of the scavenging pump, and through the return oil passage. The purpose is to promote the return of the lubricating oil to the crank chamber. A second object of the present invention is to further promote gas-liquid separation for the lubricating oil discharged from the scavenging pump.

  The invention according to claim 1 is an internal combustion engine provided with a valve chamber in which a valve operating device for opening and closing an intake valve and an exhaust valve is accommodated, and a crank chamber in which a crankshaft that is rotationally driven by a piston is accommodated. A feed pump that pumps the lubricating oil in the oil tank to a lubricating location; a scavenging pump that collects the lubricating oil in the crank chamber and discharges it to the oil tank; and the lubricating oil and gas in the valve chamber are In the internal combustion engine including a dry sump type lubrication device including an outflow passage that flows out to the outside of the chamber, the outflow passage includes only a return oil passage that is the only communication passage that connects the valve chamber and the crank chamber. In addition, the lubricating oil in the valve operating chamber and the breathing gas introduced to the valve operating chamber through the breather passage from other than the crank chamber pass only through the return oil passage. Serial is an internal combustion engine to be led to the crank chamber.

  According to this, the lubricating oil in the valve operating chamber is guided to the crank chamber through the return oil passage that is the only passage through which the lubricating oil and gas in the valve operating chamber flow out of the valve operating chamber. At the same time, the suction of the scavenging pump causes the crank chamber to be in a decompressed state, so that the suction force that sucks the lubricating oil and breathing gas in the valve chamber into the crank chamber is concentrated in the return passage that is the only passage. Therefore, the return of the lubricating oil through the return oil passage is suppressed, and further, the breathing gas in the valve operating chamber is also guided to the crank chamber through the return oil passage, so that the flow toward the return oil passage in the valve operating chamber is achieved. The breathing gas attracts the lubricating oil to the return oil passage, and in the return oil passage, the breathing gas flowing through the return oil passage promotes the flow of the lubricating oil toward the crank chamber.

  According to a second aspect of the present invention, in the internal combustion engine according to the first aspect, the lubricating device includes a gas-liquid separator that separates blow-by gas mixed in the lubricating oil from the scavenging pump, and the oil cooler. The lubricating oil discharged from the scavenging pump is guided to the gas-liquid separator before being cooled by the oil cooler.

  According to this, since the blow-by gas is separated from the high-temperature lubricating oil before being cooled by the oil cooler, the blow-by gas is efficiently separated.

  According to invention of Claim 1, the following effect is show | played. In other words, by utilizing the fact that the crank chamber is depressurized by the suction of the scavenging pump, the suction of the lubricating oil is suppressed by the increase of the suction force, and further, the breathing gas flowing through the return oil passage causes the return oil passage through the return oil passage. Since the return of the lubricating oil to the crank chamber can be promoted, the return amount of the lubricating oil can be increased, and the required amount of the lubricating oil can be reduced. In addition, since it is not necessary to provide a separate pump for causing the lubricating oil in the valve chamber to flow out of the valve chamber, the number of parts and cost can be reduced.

  According to invention of Claim 2, in addition to the effect of the invention of the cited claim, there exists the following effect. That is, gas-liquid separation with respect to the lubricating oil discharged from the scavenging pump is promoted, and deterioration of the lubricating oil due to mixing of blow-by gas is prevented or suppressed.

Embodiments of the present invention will be described below with reference to FIGS.
Referring to FIGS. 1 and 2, an internal combustion engine E to which the present invention is applied is an OHC type V-type 6-cylinder 4-stroke internal combustion engine, and is mounted on a vehicle in a lateral arrangement in which a crankshaft 8 is oriented in the vehicle width direction. Installed. The water-cooled internal combustion engine E includes a cylinder block 1 having a cylinder row arranged in a V shape when viewed from the rotation center line direction of the crankshaft 8, an oil pan 2 coupled to one end of the cylinder block 1, The engine main body includes a pair of cylinder heads 3a and 3b coupled to the other end of the cylinder block 1 and a pair of head covers 4a and 4b coupled to the pair of cylinder heads 3a and 3b, respectively. .

  Each of the front bank Ba as the first bank and the rear bank Bb as the second bank constituting the V bank, respectively, includes three cylinders 1a (one of which is shown in the figure) constituting the first cylinder row. ) And three cylinders 1b (one of which is shown in the figure) constituting the second cylinder row. The front bank Ba includes a cylinder head 3a and a head cover 4a in addition to the cylinder 1a, and the rear bank Bb includes a cylinder head 3b and a head cover 4b in addition to the cylinder 1b, and between the banks Ba and Bb. A bank space 5 is formed.

  Referring to FIG. 2, a piston 6 slidably fitted in a cylinder hole of each of the cylinders 1 a and 1 b and reciprocating is connected to a crankshaft 8 via a connecting rod 7. The crankshaft 8 is housed in a crank chamber 10 formed by a crankcase 9 constituted by the skirt portion 1c of the cylinder block 1 and the oil pan 2, and is rotatably supported by a bearing portion provided in the crankcase 9. Is done.

  Each cylinder head 3a, 3b includes, for each cylinder 1a, 1b, a combustion chamber 11 facing the cylinder hole in the cylinder axial direction, an intake port 12 opened to the combustion chamber 11, and an exhaust port opened to the combustion chamber 11. Further, an intake valve 14 for opening and closing the intake port 12, an exhaust valve 15 for opening and closing the exhaust port 13, and an ignition plug (not shown) facing the combustion chamber 11 are provided.

  The intake valve 14 and the exhaust valve 15 are opened and closed by a valve operating device 21 housed in a valve operating chamber 20 formed by the cylinder heads 3a and 3b and the head covers 4a and 4b for each of the banks Ba and Bb. The valve operating device 21 is supported by the cylinder heads 3a and 3b so as to be rotatable and is driven to rotate by the crankshaft 8. The valve operating device 21 is provided with intake air via a camshaft 22 and a rocker arm 24 provided on the camshaft 22 as a plurality of cam followers. And a plurality of valve cams 23 for opening and closing the valve 14 and the exhaust valve 15.

  Referring also to FIG. 1, the internal combustion engine E includes an intake device 25 that forms an intake passage 26 that guides intake air to each intake port 12, and an air-fuel mixture forming means that supplies fuel to the intake air to form an air-fuel mixture. And an exhaust device 28 that forms an exhaust passage for guiding the exhaust gas from each combustion chamber 11 through the exhaust port 13 to the outside of the internal combustion engine E.

  The intake device 25 includes an air cleaner 25a, a throttle valve 25b, and a pair of intake manifolds 25c and 25d that distribute intake air measured by the throttle valve 25b to the cylinders 1a and 1b. A pair of intake manifolds 25c, 25d arranged on the bank space 5 side with respect to each bank Ba, Bb is coupled to the cylinder heads 3a, 3b so that the intake passage 26 communicates with the intake port 12. The exhaust device 28 also includes a pair of exhaust manifolds 28c and 28d. Both exhaust manifolds 28c and 28d disposed on the opposite side of the bank space 5 with respect to the respective banks Ba and Bb are coupled to the cylinder heads 3a and 3b so that the exhaust passage communicates with the exhaust port 13.

  Then, the intake air sucked through the intake passage 26 is mixed with the fuel from the fuel injection valve 27 and flows into the combustion chamber 11, where it is ignited and burned by the spark plug in the combustion chamber 11, and the generated combustion gas The piston 6 that is driven by pressure and reciprocates drives the crankshaft 8 through the connecting rod 7. The combustion gas is discharged outside the internal combustion engine E through the exhaust passage as exhaust gas.

  With reference to FIG. 1, the lubrication apparatus provided in the internal combustion engine E will be described. The lubricating device that circulates the lubricating oil and supplies the lubricating oil to each lubricating location (hereinafter simply referred to as “lubricating location”) of the internal combustion engine E is constituted by a dry sump type lubricating device, and the oil stored in the lubricating oil The tank 31, a feed pump 32 that pumps the lubricating oil pumped up from the oil tank 31 to be supplied to each lubricating point through the main oil passage 43 provided in the engine body, and the lubricating oil discharged from the feed pump 32 An oil filter 33 to be cleaned, an oil pan 2 that constitutes a lower part of the crankcase 9 and collects lubricating oil after lubricating each lubrication point, and is stored in the oil pan 2 in the crank chamber 10 Scavenging pump 34 that collects the discharged lubricating oil and discharges it to oil tank 31, gas-liquid separator 35 to which the lubricating oil discharged from scavenging pump 34 is guided, and scavenging An oil cooler 36 that cools the lubricating oil discharged from the group pump 34 and oil passages including the main oil passage 43 and the return oil passage 44 are provided.

  The scavenging pump 34 driven by the power of the crankshaft 8 together with the feed pump 32 has a larger pump capacity than the feed pump 32 and sucks blow-by gas and air in the crank chamber 10 together with the lubricating oil. As a result, the crank chamber 10 is decompressed. In the gas-liquid separator 35 provided in the recovery oil passage 45 that guides the lubricating oil discharged from the scavenging pump 34 to the oil tank 31, the oil cooler 36 provided downstream of the gas-liquid separator 35 in the recovery oil passage 45. Before being cooled, the blow-by gas and the gas containing air mixed in the lubricating oil discharged from the scavenging pump 34 are separated.

The oil tank 31 includes a main oil tank 31a and a sub oil tank 31b having a smaller volume than the main oil tank 31a. The main oil tank 31 a is provided with a gas-liquid separator 37 that separates blow-by gas and air discharged from the scavenging pump 34 and mixed in the lubricating oil that has passed through the gas-liquid separator 35 and the oil cooler 36. The gas-liquid separator 37 incorporated in the main oil tank 31a is a low-temperature cooled by the oil cooler 36 with respect to the high-temperature gas-liquid separator 35 to which the high-temperature lubricating oil before being cooled by the oil cooler 36 is guided. This is a low-temperature side gas-liquid separator 37 through which the lubricating oil is introduced. Both the gas-liquid separators 35 and 37 are constituted by known gas-liquid separators such as a type having a large number of baffle plates or a type using centrifugal force.
An oil strainer 38 is disposed in the sub oil tank 31b, and the lubricating oil from which foreign matter has been removed by the oil strainer 38 is sucked into the feed pump 32 through a suction oil passage 41 provided with a check valve 39.

  The lubricating oil discharged from the feed pump 32 and passing through the oil filter 33 provided in the discharge oil passage 42 is supplied to the main oil passage 43 provided in the cylinder block 1, and the lubricating oil in the main oil passage 43 is supplied to the crankshaft. The oil is guided to the respective lubrication points such as the shaft 8, the piston 6 and the valve gear 21 through a number of oil passages. Then, the lubricating oil after lubricating each lubricated portion gathers in the oil pan 2.

  Referring also to FIG. 2, the lubricating oil after lubricating each lubricating location including the valve operating device 21 in the valve operating chamber 20 formed by the cylinder heads 3 a and 3 b is provided for each of the banks Ba and Bb. The cylinder heads 3a and 3b and the cylinder block 1 extending to the skirt portion 1c are returned to the crank chamber 10 through one or a plurality of return oil passages 44 in this embodiment. Set to 2.

  In each bank Ba, Bb, each return oil passage 44 is the only communication path that connects the valve train chamber 20 and the crank chamber 10 and is supplied to the valve train chamber 20 for lubrication of the valve train 21. Thus, only the outflow passage for allowing the lubricating oil, that is, the lubricating oil in the valve operating chamber 20 and the gas present in the valve operating chamber 20 to flow out to the outside of the valve operating chamber 20 is configured. The valve operating chamber 20 is formed by cylinder heads 3a and 3b as part of the valve operating chamber 20, and collects the lubricating oil in the valve operating chamber 20 and opens the inlet of the return oil passage 44. A portion 20a is provided. For this purpose, the oil collecting portion 20a is formed at the lowest position of the valve operating chamber 20, or the lubricating oil flows through the upper decks 3a1, 3b1 of the cylinder heads 3a, 3b constituting the bottom wall of the valve operating chamber 20. The oil collecting portion 20a can be recessed or inclined so as to be easily collected.

  The lubricating oil discharged from the scavenging pump 34 and degassed by the gas-liquid separator 35 is cooled by the oil cooler 36 and then led to the gas-liquid separator 37 and mixed in the lubricating oil. Blow-by gas and air are further separated. Then, the lubricating oil from which the blow-by gas and air are separated is stored in the main oil tank 31a and then sucked into the feed pump 32.

  With reference to FIG. 1 again, a blow-by gas reduction device provided in the internal combustion engine E for returning the blow-by gas leaking from between the cylinders 1a, 1b and the piston 6 to the intake passage 26 will be described. The blow-by gas reduction device includes an introduction system that guides the breathing gas to the valve operating chamber 20, a return oil passage 44 that guides the breathing gas in the valve operating chamber 20 to the crank chamber 10, and a scavenging pump 34 for lubricating oil. A recovery system that guides the blow-by gas in the crank chamber 10 sucked together to the crank chamber 10 and a recirculation system that guides the blow-by gas in the crank chamber 10 to the intake passage 26 are provided.

  The introduction system connects a portion 26a upstream of the throttle valve 25b in the intake passage 26 with the main oil tank 31a, a fresh air passage 51 for guiding fresh air as intake air to the tank internal space 31a1, and a main oil The main oil tank 31a includes a breather passage 52 that communicates the tank 31a with the valve chambers 20 of the banks Ba and Bb to guide the blow-by gas and air in the tank space 31a1 to the valve chambers 20. . Therefore, fresh air and blow-by gas and air separated by the gas-liquid separators 35 and 37 are introduced into the valve operating chamber 20 from the portion other than the crank chamber 10 through the breather passage 52 as the breathing gas.

  The return oil passage 44 guides the breathing gas (blow-by gas and air) from the valve operating chamber 20 to the crank chamber 10 that is in a decompressed state by suction of the scavenging pump 34. At this time, the blow-by gas and air guided to the valve operating chamber 20 are guided to the crank chamber 10 only through the return oil passage 44.

  The recovery system includes a recovery passage 53 that connects the gas-liquid separator 35 and the main oil tank 31a to guide blow-by gas and air separated by the gas-liquid separator 35 to the tank internal space 31a1. Accordingly, the recovery passage 53 communicates with the introduction system.

  The recirculation system connects the crank chamber 10 and the intake passage 26 downstream of the throttle valve 25b and communicates with the portions 26c and 26d formed by the intake manifolds 25c and 25d. And a return passage 54 for introducing air to the portions 26c and 26d, and return of blow-by gas and air according to engine operating conditions such as a load of the internal combustion engine (for example, negative pressure in the intake passage 26). And a PCV valve 55 as a control valve for controlling the flow rate.

Next, operations and effects of the embodiment configured as described above will be described.
In the lubrication apparatus, when the internal combustion engine E is operated and the feed pump 32 and the scavenging pump 34 are driven, the lubricating oil discharged from the feed pump 32 is supplied to each lubrication location of the internal combustion engine E. The lubricating oil after lubricating the oil gathers in the oil pan 2 in the crank chamber 10. The lubricating oil sucked from the oil pan 2 and discharged from the scavenging pump 34 is separated into blow-by gas and air by the gas-liquid separator 35, further cooled by the oil cooler 36, and then blow-by by the gas-liquid separator 37. Gas and air are further separated. The main oil tank 31a stores the lubricating oil after the blow-by gas and air are separated, and the lubricating oil is sucked into the feed pump 32. On the other hand, in the blow-by gas reduction device, the blow-by gas and air separated by the gas-liquid separator 35 are guided to the valve operating chamber 20 together with fresh air from the fresh air passage 51, and are further reduced in pressure through the return oil passage 44. Guided to some crank chamber 10. The blow-by gas in the crank chamber 10 is guided to the intake passage 26 when the PCV valve 55 is opened, and further flows into the combustion chamber 11 and burns.

At this time, the outflow passage through which the lubricating oil, blow-by gas, and air in the valve operating chamber 20 flow out to the outside of the valve operating chamber 20 is the only communication passage that allows the valve operating chamber 20 and the crank chamber 10 to communicate with each other. The lubricating oil in the valve operating chamber 20 and the blow-by gas and air guided to the valve operating chamber 20 are configured only by the return oil passage 44 and are guided to the crank chamber 10 through the return oil passage 44 only.
As a result, the lubricating oil in the valve operating chamber 20 is transferred to the crank chamber 10 through the return oil passage 44, which is the only passage through which the lubricating oil, blow-by gas, and air in the valve operating chamber 20 flow out of the valve operating chamber 20. Led. At the same time, the suction of the scavenging pump 34 causes the crank chamber 10 to be depressurized, so that the suction force that sucks the lubricating oil, blow-by gas, and air in the valve operating chamber 20 into the crank chamber 10 is the only passage. Since it is enhanced by concentrating on the oil passage 44, the lubricant oil is prevented from returning through the return oil passage 44, and blow-by gas and air in the valve operating chamber 20 are also led to the crank chamber 10 through the return oil passage 44. Thus, in the valve operating chamber 20, blow-by gas and air toward the return oil passage 44 attract the lubricating oil to the return oil passage 44. Further, in the return oil passage 44, blow-by gas and air flowing through the return oil passage 44 The flow of lubricating oil toward the crank chamber 10 is promoted.
As a result, utilizing the fact that the crank chamber 10 is in a reduced pressure state due to the suction of the scavenging pump 34, the increase of the suction force suppresses the injection of the lubricating oil, and further, by the blow-by gas and air flowing through the return oil passage 44, Since the return of the lubricating oil to the crank chamber 10 through the return oil passage 44 can be promoted, the return amount of the lubricating oil can be increased, and the required amount of the lubricating oil can be reduced. In addition, since it is not necessary to provide a separate pump for causing the lubricating oil in the valve chamber 20 to flow out of the valve chamber 20, the number of parts and the cost can be reduced. Furthermore, since there is no power loss that occurs when the other pump is driven by the power of the crankshaft 8, fuel efficiency is improved.

  The lubricating oil discharged from the scavenging pump 34 is guided to the gas-liquid separator 35 before being cooled by the oil cooler 36, so that the blow-by gas is separated from the high-temperature lubricating oil before being cooled by the oil cooler 36. Therefore, blow-by gas is efficiently separated. As a result, gas-liquid separation with respect to the lubricating oil discharged from the scavenging pump 34 is promoted, and deterioration of the lubricating oil due to mixing of blow-by gas is prevented or suppressed.

  Moreover, since gas-liquid separation is performed by the gas-liquid separator 35 on the high temperature side and the gas-liquid separator 37 on the low temperature side, the blow-by gas and air can be more efficiently separated from the lubricating oil discharged from the scavenging pump 34. Done.

  In addition to the fresh air, blow-by gas and air separated by the gas-liquid separators 35 and 37 flow into the return oil passage 44, so that only fresh air flows through the return oil passage 44. Since the blow-by gas and air separated by the gas-liquid separators 35 and 37 flow at a high flow rate, the return of the lubricating oil is further promoted.

Hereinafter, an embodiment in which a part of the configuration of the above-described embodiment is changed will be described with respect to the changed configuration.
The internal combustion engine may be a multi-cylinder internal combustion engine other than the V type, or may be a single cylinder internal combustion engine. Further, each valve chamber 20 and the crank chamber 10 may be communicated with each other by one return oil passage 44.
The introduction system may be configured by only the fresh air passage 51 that directly communicates with the valve operating chamber 20, and at this time, the recovery system includes a breather passage 52, a recovery passage 53, and a main oil tank 31a. Further, in this case, the breather passage 52 may directly communicate with the crank chamber 10, and the recovery passage 53 may directly communicate with the valve operating chamber 20 or the crank chamber 10.
The return oil passage 44 may be formed by a conduit without being formed in the engine body.
The internal combustion engine is used for a vehicle in the above embodiment, but may be used for a ship propulsion device such as an outboard motor having a crankshaft oriented in the vertical direction. It may be used for a machine.

1 is a schematic diagram of an internal combustion engine to which the present invention is applied, showing an embodiment of the present invention. FIG. 2 is an enlarged view of a main part showing a part of the engine body of the internal combustion engine of FIG. 1 in cross section.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Cylinder block, 2 ... Oil pan, 3a, 3b ... Cylinder head, 4a, 4b ... Head cover, 5 ... Bank space, 6 ... Piston, 7 ... Connecting rod, 8 ... Crankshaft, 9 ... Crankcase, 10 ... Crank chamber , 11 ... Combustion chamber, 12 ... Intake port, 13 ... Exhaust port, 14 ... Intake valve, 15 ... Exhaust valve, 20 ... Valve train, 20a ... Oil collecting part, 21 ... Valve train, 22 ... Camshaft, 23 ... valve cam, 24 ... rocker arm, 25 ... intake device, 26 ... intake passage, 27 ... fuel injection valve, 28 ... exhaust device, 31 ... oil tank, 32 ... feed pump, 33 ... oil filter, 34 ... scavenging pump 35 ... Gas-liquid separator, 36 ... Oil cooler, 37 ... Gas-liquid separator, 38 ... Oil strainer, 39 ... Check valve, 41 ... Suction oil passage, 42 ... Discharge oil passage, 43 ... Main oil passage, 44 ... Return oil passage, 51 ... Fresh air passage, 52 ... Breather passage, 53 ... Recovery passage, 54 ... Recirculation passage, 5 5 ... PCV valve,
E: Internal combustion engine, Ba, Bb ... Bank.

Claims (2)

An internal combustion engine provided with a valve operating chamber that houses a valve operating device that opens and closes an intake valve and an exhaust valve, and a crank chamber that houses a crankshaft that is rotationally driven by a piston. A feed pump that pumps oil; a scavenging pump that collects lubricating oil in the crank chamber and discharges it to the oil tank; and an outflow passage that allows the lubricating oil and gas in the valve chamber to flow out of the valve chamber In an internal combustion engine comprising a dry sump type lubrication device comprising:
The outflow passage is constituted only by a return oil passage that is the only communication passage for communicating the valve chamber and the crank chamber, and the oil is supplied from outside the crank chamber through the breather passage. The internal combustion engine, wherein the breathing gas guided to the valve chamber is guided to the crank chamber only through the return oil passage. The lubricating device includes a gas-liquid separator that separates blow-by gas mixed in lubricating oil from the scavenging pump, and the oil cooler, and the lubricating oil discharged from the scavenging pump is the oil cooler. 2. The internal combustion engine according to claim 1, wherein the internal combustion engine is guided to the gas-liquid separator before being cooled by the gas.

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