JP2012241658A - Blow-by gas ventilation system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blow-by gas ventilation system for internal combustion engine, including an engine body housing a crank chamber connected to a cylinder bore and an auxiliary equipment chamber where auxiliary equipment linked and connected to a crankshaft, across a partition wall, and the engine body being connected to a new introduction passage guiding outside air to the crank chamber and a blow-by gas return passage for returning blow-by gas in the crank chamber to a suction system downstream from a cleaner element of an air cleaner, while effectively discharging the blow-by gas from the crank chamber.SOLUTION: A communication hole 85 which connects a crank chamber 51 and an auxiliary equipment chamber 52 leading to a blow-by gas return passage 83 is formed in a partition 18a. A fan 86 which generates the flow of air from the crank chamber 51 to the auxiliary equipment chamber 52 through the communication hole 85 is arranged in the auxiliary equipment chamber 52 so as to rotate along with the crankshaft.

Description

  The present invention provides a partition between a crank chamber that communicates with a cylinder bore in which a piston is slidably fitted, and an accessory chamber that houses an accessory linked to and connected to a crankshaft connected to the piston. A new introduction passage that is formed in the engine body with the intervening air and guides the outside air to the crank chamber, and a blow-by gas return passage for returning the blow-by gas in the crank chamber to the intake system downstream of the cleaner element provided in the air cleaner; Relates to a blow-by gas ventilation device for an internal combustion engine connected to the engine body.

  A blow-by gas ventilator that uses the pressure fluctuation in the crank chamber accompanying the sliding of the piston in the cylinder bore to return the blow-by gas in the crank chamber to the intake system downstream of the cleaner element of the air cleaner is, for example, a patent It is known from Document 1 etc.

Japanese Patent Laid-Open No. 2005-121008

  However, the one disclosed in Patent Document 1 utilizes the pressure fluctuation of the crank chamber, and in an internal combustion engine having a large crank chamber volume, blow-by gas is more effectively discharged from the crank chamber. It is desirable.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a blow-by gas ventilation device for an internal combustion engine that can effectively discharge blow-by gas from a crank chamber.

  In order to achieve the above object, the present invention provides an auxiliary machine that houses a crank chamber that communicates with a cylinder bore into which a piston is slidably fitted, and an auxiliary machine that is linked and connected to a crankshaft connected to the piston. Are formed in the engine body with a partition between them, and a new introduction passage for guiding outside air to the crank chamber, and the blow-by gas in the crank chamber to the intake system downstream of the cleaner element provided in the air cleaner. In the blow-by gas ventilating apparatus for an internal combustion engine in which a blow-by gas return passage for returning is connected to the engine body, a communication hole is provided for communicating between the crank chamber and the auxiliary equipment chamber communicating with the blow-by gas return passage. A fan that is provided in the partition wall and causes a gas flow from the crank chamber to the auxiliary machine chamber through the communication hole is provided in the cylinder. So as to rotate in conjunction with the Kushafuto the first feature to be disposed in the auxiliary chamber.

  According to the present invention, in addition to the configuration of the first feature, a clutch for connecting / disconnecting power transmission between the crankshaft and the transmission is housed as the accessory in the accessory chamber, and the fan is connected to the clutch. The second feature is that it is provided in the above.

  In addition to the configuration of the second feature, the present invention provides a clutch outer provided in the clutch with a driven gear constituting a part of a primary reduction gear provided between the clutch outer and the crankshaft. A third feature is that a press plate that is pressed and held so as to be sandwiched therebetween is attached, and a plurality of fins are integrally formed on the press plate by press molding to constitute the fan.

  According to the present invention, in addition to the configuration of the third feature, the input shaft of the transmission passes through the partition wall rotatably and is relatively non-rotatably connected to the clutch inner of the clutch. A fourth feature is that it is formed in an arc shape surrounding a part of the bearing member provided between the partition wall and the input shaft.

  According to the present invention, in addition to the configuration of the fourth feature, a stopper plate for preventing the bearing member from being detached from the partition is provided between at least two communication holes arranged so as to surround the bearing member. A fifth feature is that mounting bosses provided on the partition walls are arranged on the wall.

  Furthermore, in the present invention, in addition to the configuration of the third or fourth feature, an inner cylinder portion disposed inside the communication hole, and an outer cylinder portion disposed outside the communication hole are provided on the fan. A sixth feature is that the partition wall is provided so as to extend toward the inner peripheral portion.

  The gear transmission 47 of the embodiment corresponds to the transmission of the present invention, and the ball bearing 55 of the embodiment corresponds to the bearing member of the present invention.

  According to the first feature of the present invention, the fan that rotates in conjunction with the crankshaft is housed in the auxiliary machine chamber that communicates with the blow-by gas return passage, and the communication hole provided in the partition wall separating the crank chamber and the auxiliary machine chamber is provided. Since the gas flows from the crank chamber to the auxiliary machine chamber through rotation of the fan, the gas can actively flow from the crank chamber to the auxiliary machine room, and blow-by gas is effectively discharged from the crank chamber. And deterioration of the oil by blow-by gas can be prevented effectively.

  Further, according to the second feature of the present invention, since the fan is provided in the clutch housed in the auxiliary machine chamber so that the power transmission between the crankshaft and the transmission is disconnected and connected, By providing the fan, the size of the fan can be increased, and the increase in the number of parts and the number of assembly steps can be suppressed while the blow-by gas is led out from the crank chamber more effectively.

  According to the third aspect of the present invention, a plurality of fins are integrally formed by press molding on the presser plate that holds the driven gear so as to be sandwiched between the clutch outer of the clutch and the fan is configured. Therefore, it is possible to easily form a fan while improving productivity.

  According to the fourth aspect of the present invention, a part of the bearing member provided between the partition wall and the input shaft of the transmission, which is connected to the clutch inner of the clutch so as not to rotate relative to the clutch inner wall and rotatably penetrates the partition wall, is provided. Since the communication hole is formed in an arc shape so as to surround, the communication hole can be made relatively large along the rotation direction of the fan, and the blow-by gas can be led out from the crank chamber more effectively to improve the ventilation performance. .

  According to the fifth aspect of the present invention, the mounting boss provided on the partition wall is arranged between the at least two communication holes to mount the stopper plate for preventing the bearing member from being detached from the partition wall. It is possible to reinforce the periphery of the communication hole with a boss, and it is possible to increase the opening area of the communication hole while avoiding a decrease in the strength of the partition wall, enabling more effective derivation of blow-by gas from the crank chamber Become.

  Further, according to the sixth aspect of the present invention, the negative suction pressure of the fan is effectively applied to the communication hole by the inner cylinder part inside the communication hole and the outer cylinder part outside the communication hole. The blow-by gas can be more effectively derived from the.

It is a figure which shows the structure of the blow-by gas ventilation apparatus of the internal combustion engine of 1st Embodiment. FIG. 2 is an enlarged view of a portion indicated by an arrow 2 in FIG. 1. FIG. 3 is a sectional view taken along line 3-3 in FIG. 2. FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. It is the front view which looked at the air cleaner from the 5 arrow direction of FIG. Fig. 6 is a view taken along line 6-6 in Fig. 5. FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. 6. It is a front view of a presser plate. It is a front view corresponding to Drawing 5 of an air cleaner of a 2nd embodiment.

  Embodiments of the present invention will be described with reference to the accompanying drawings.

  A first embodiment of the present invention will be described with reference to FIGS. 1 to 8. First, in FIG. 1, the internal combustion engine is mounted on, for example, a motorcycle. A crankcase 12 for rotatably supporting a crankshaft 16 extending in the width direction; a cylinder block 13 having a cylinder bore 17 whose axis is inclined forwardly upward; and coupled to the front upper portion of the crankcase 12; A cylinder head 14 coupled to the upper portion of the block 13 and a head cover 15 coupled to the cylinder head 14 are provided.

  2 and 3, the crankcase 12 includes a right case half 18 disposed on the right side in the vehicle width direction and a left case half 19 disposed on the left side in the vehicle width direction. They are coupled by a coupling surface 20 along a plane orthogonal to the axis of the crankshaft 16. A piston 21 is slidably fitted in the cylinder bore 17 of the cylinder block 13, and the piston 21 is connected to the crankshaft 16 via a connecting rod 22. A combustion chamber 23 facing the top of the piston 21 is formed between the cylinder block 13 and the cylinder head 14, and an intake port 24 that can communicate with the combustion chamber 23 is provided on a rear side wall of the cylinder head 14. An exhaust port 25 that can communicate with the chamber 23 is provided on the front side wall of the cylinder head 14.

  The cylinder head 14 is provided with an intake valve 26 for controlling the intake amount from the intake port 24 to the combustion chamber 23 so as to be able to open and close, and the exhaust amount from the combustion chamber 23 to the exhaust port 25. The intake valve 26 and the exhaust valve 27 are urged in the valve closing direction by valve springs 28 and 29, respectively.

  The intake system 30 connected to the intake port 24 includes an air cleaner 31, a connecting tube 32 connected to the air cleaner 31 at the upstream end, a vaporizer 33 connected to the downstream end of the connecting tube 32, and the vaporizer And an intake pipe 34 connecting the intake port 24 and the intake port 24.

  The air cleaner 31 is configured by a cleaner element 37 housed in a cleaner case 36 having a suction pipe 35 opened rearward, and the cleaner element 37 includes an unpurified chamber 38 communicating with the suction pipe 35, and The cleaner case 36 is partitioned into the purification chamber 39, and the connecting tube 32 penetrates the cleaner case 36 so that the upper end of the connecting tube 32 enters the purification chamber 39.

  A valve operating device 41 that opens and closes the intake valve 26 and the exhaust valve 27 includes a camshaft 42 having an axis parallel to the crankshaft 16, and is formed between the cylinder head 14 and the head cover 15. The valve operating chamber 43 is accommodated.

  Referring also to FIG. 4, the rotational power of the crankshaft 16 is output via a primary reduction device 44, for example, a pair of damper springs 45, a clutch 46 and a gear transmission 47.

  The gear transmission 47 is provided between the input shaft 48 and the output shaft 49 so as to be able to be selectively established with an input shaft 48 and an output shaft 49 whose both ends are rotatably supported by the crankcase 12. A gear train having a plurality of shift speeds, and a shift drum 50 having an axis parallel to the input shaft 48 and the output shaft 49 and rotatably supported on the crankcase 12. The gear transmission 47 is accommodated together with most of the crankshaft 16 in a crank chamber 51 formed in the crankcase 12 so as to communicate with the crankcase 12.

  A right cover 53 constituting a part of the engine body 11 is fastened to the right case half 18 so as to form an auxiliary machine chamber 52 between the right case half 18 and the right case half 18. The auxiliary reduction chamber 44 and the damper spring 45 and the clutch 46, which is an auxiliary device linked and connected to the crankshaft 16, are accommodated in the auxiliary machine chamber 52.

  A part of the right case half 18 in the crankcase 12 serves as a partition wall 18a interposed between the crank chamber 51 and the auxiliary machine chamber 52. The crankshaft 16 and the input of the gear transmission 47 The shaft 48 rotatably penetrates the partition wall 18a and enters the auxiliary machine chamber 52. A roller bearing 54 is interposed between the crankshaft 16 and the partition wall 18a, and the input shaft 48 and the shaft A ball bearing 55 as a bearing member is interposed between the partition walls 18a.

  Referring to FIG. 1, the crankcase 12, the cylinder block 13, and the cylinder block 12 of the engine body 11 are located on the side opposite to the auxiliary machine chamber 52, that is, on the left side of the engine body 11 with respect to the axis of the cylinder bore 17, that is, the cylinder axis C. The cylinder head 14 has a cam chain chamber 56 for running a cam chain that constitutes a part of a timing transmission device that transmits rotational power from the crankshaft 16 to the camshaft 42 of the valve gear 41. The gas in the valve operating chamber 43 is formed and can flow to the crank chamber 51 side through the cam chain chamber 56.

  The cleaner case 36 of the air cleaner 31 is provided with a first connection pipe 57 that communicates with a purification chamber 39, and the head cover 15 is provided with a second connection pipe 58 that communicates with the valve operating chamber 43, and The second connection pipes 57 and 58 are connected by a first pipe 59 such as a rubber hose. Thus, the first connecting pipe 57, the first pipe 59 and the second connecting pipe 58 form a new introduction passage 60, and the valve operating chamber 43 enters the crank chamber 51 through the cam chain chamber 56. Since the communication is made, the new introduction passage 60 guides the outside air to the crank chamber 51.

  3 and 4, the clutch 46 includes a clutch outer 61 that is rotatably supported at one end of the input shaft 48, and a plurality of first friction members that are engaged with the clutch outer 61. .., A plurality of clutch inners 63 that are coupled to the input shaft 48 in a relatively non-rotatable manner, and a plurality of first friction plates 62 that are engaged with the clutch inner 63. Of the first and second friction plates 62, 62 ...; 64, 64 ... arranged alternately, opposite to the axially outward friction plate, and integrated with the clutch inner 63. Of the first and second friction plates 62, 62... 64, 64... That are movable in the direction parallel to the input shaft 48 and are alternately arranged. Plate with the outer circumference facing the friction plate Between the pressure receiving plate 65 and the pressure member 66, a retainer 68 fastened with bolts 67 to the distal ends of a plurality of connecting tube portions 66a that are integrally connected to the pressing member 66 at the base end. A clutch spring 69 interposed between the clutch inner 63 and the retainer 68 so as to urge the pressing member 66 toward the side to which the first and second friction plates 62, 62... 64, 64. A lifter 71 connected to the inner peripheral portion of the retainer 68 via a release bearing 70 is provided. A shift operation shaft 72 that is rotatably fitted to the right cover 53 is attached to the lifter 71. It is linked and connected so that it can be driven in the axial direction.

  In such a clutch 46, when the shift operation shaft 72 is not operated, the pressing member 66 is urged to the engagement side by the clutch spring 69, so that the clutch 46 is in a power transmission state. Next, when the shift operation shaft 72 is operated and the lifter 71 is operated in the axial direction, the driving force is transmitted from the release bearing 70 to the retainer 68, and the retainer 68 compresses the clutch spring 69. The first and second friction plates 62, 62... 64, 64... Press the pressing member 66 to the side where the crimping force is weakened, and the power transmission between the clutch outer 61 and the clutch inner 63 is interrupted. Become.

  Referring to FIG. 3, the primary reduction gear 44 is supported by the drive gear 74 fixed to the crankshaft 16 in the accessory chamber 52 and the input shaft 48 so as to be relatively rotatable, and the drive gear 74. The driven gear 75 is engaged with the clutch outer 61 via the damper springs 45.

  Thus, a presser plate 76 is attached to the clutch outer 61 by a plurality of rivets 77 for holding the driven gear 75 so as to be sandwiched between the clutch outer 61 and the damper spring 45. Is held between the presser plate 76 and the clutch outer 61.

  A maze-like breather chamber 78 into which blow-by gas in the crank chamber 51 is introduced is formed at the upper portion of the crankcase 12, and an inlet hole that allows the breather chamber 78 to communicate with the upper portion of the auxiliary machine chamber 52. 79 is provided in the right case half 18 of the crankcase 12. A third connecting pipe 80 that communicates with the breather chamber 78 is provided on the crankcase 12 above the right case half 18. On the other hand, the cleaner case 36 in the air cleaner 31 is provided with a fourth connection pipe 81 leading to the purification chamber 39, and the third and fourth connection pipes 80, 81 are connected by a second pipe line 82 such as a rubber hose. It is. Thus, the third connecting pipe 80, the second pipe 82, and the fourth connecting pipe 81 form a blow-by gas return passage 83. The blow-by gas return passage 83 is formed by the cleaner element 37 provided in the air cleaner 31. Also, the blow-by gas is returned to the intake system 30 on the downstream side.

  5 to 7, the cleaner case 36 of the air cleaner 31 includes a case main body 94 opened upward, and a plurality of cleaner cases 37 sandwiched between the case main body 94 and an upper portion of the case half 94. Are connected by screw members 96, 96..., And a connection hole 97 that airtightly penetrates the upstream end of the connecting tube 32 in the intake system 30 is provided in the direction of travel of the motorcycle. It is provided on the front right side of the case main body 94.

  Below the connection hole 97, at the front portion of the case main body 94, a substantially L-shaped wall portion 94a having both end portions connected to the side wall of the case main body 94, and the case main body 94 facing the wall portion 94a. The partition wall portion 94b protruding from the side wall is integrally provided with the upper ends of the 94a and 94b being flush with each other, and the step portion 94c that is flush with the upper ends of the wall portion 94a and the partition wall portion 94b is the above-described step. It is formed on the inner surface of the middle part of the side wall of the case main body 94. Thus, the flat lid plate 98 with the peripheral edge abutting against the upper ends of the wall portion 94a and the partition wall portion 94b and the stepped portion 94c forms a return chamber 99 with the case main body 94. Thus, the case main body 94 is fixed.

  The case main body 94 is provided with a fourth connecting pipe 81 on the left side of the partition wall portion 94b so as to communicate with the return chamber 99, and the return chamber 99 is connected to the purification chamber 39 on the right side of the partition wall portion 94b. The lid plate 98 is provided with a communication hole 100 that communicates with the lid plate 98. Further, the first connection pipe 57 is provided on the case main body 94 so as to be positioned below the right side of the connection hole 97 and above the communication hole 100.

  The blow-by gas introduced into the return chamber 99 from the fourth connection pipe 81 flows between the partition wall portion 94b and the wall portion 94a to the communication hole 100 side. The blow-by gas from which the oil component has been separated by the separation action is guided from the communication hole 100 to the purification chamber 39. Further, in a state where the operation of the internal combustion engine is stopped and the motorcycle is stopped by a side stand (not shown), when the internal combustion engine is tilted to the left side, the separated oil in the return chamber 99 is blown-by gas return passage 83. Is then returned to the crankcase 12 side.

  2 to 4 again, the partition wall 18 a communicates with the crank chamber 51 and the auxiliary machine chamber 52 communicating with the blow-by gas return passage 83 through the breather chamber 78. In this embodiment, two communication holes 84 and 85 are provided, and a fan 86 that causes a gas flow from the crank chamber 51 to the auxiliary machine chamber 52 through the communication holes 84 and 85. Is arranged in the auxiliary machine chamber 52 so as to rotate in conjunction with the crankshaft 16.

  Referring also to FIG. 8, the fan 86 is provided in the clutch 46, and holds the driven gear 75 of the primary reduction gear 44 so as to be sandwiched between the clutch outer 61. Further, the fan 86 is configured by integrally forming a plurality of fins 87, 87...

  The two communication holes 84 and 85 are each formed in an arc shape surrounding a part of the ball bearing 55 provided between the partition wall 18 a and the input shaft 48. By the way, the partition wall 18a is provided with a pair of mounting bosses 90 and 90 for mounting a pair of stopper plates 88 and 88 with bolts 89 and 89 for preventing the ball bearing 55 from being detached from the partition wall 18a. One of the mounting bosses 90 is disposed between the communication holes 84 and 85.

  The partition wall 18a is disposed outside the communication holes 84 and 85 with a cross-sectional shape of, for example, a circular shape and an inner cylindrical portion 91 disposed inside the communication holes 84 and 85, and a cross-sectional shape of, for example, a circular shape. And an outer cylinder portion 92 extending integrally toward the inner peripheral portion of the fan 86, and the amount of extension of the inner cylinder portion 91 from the partition wall 18 a is determined by the partition wall of the outer cylinder portion 92. It is set larger than the amount of extension from 18a. That is, the front end of the inner cylindrical portion 91 is disposed closer to the inner peripheral portion of the fan 86 than the front end of the outer cylindrical portion 92.

  Next, the operation of the first embodiment will be described. Communication holes 84 and 85 for communicating between the crank chamber 51 and the auxiliary machine chamber 52 communicating with the blow-by gas return passage 83 are provided in the partition wall 18a. A fan 86 for generating a gas flow from the crank chamber 51 to the auxiliary machine chamber 52 through the communication holes 84 and 85 provided in 18 a is rotated in conjunction with the crankshaft 16 in the auxiliary machine chamber 52. As a result, the gas can be actively flowed from the crank chamber 51 to the auxiliary machine chamber 52, the blow-by gas is effectively discharged from the crank chamber 51, and the deterioration of the oil by the blow-by gas is effectively prevented. can do.

  Also, in the auxiliary machine chamber 52, a clutch 46 for connecting / disconnecting the power transmission between the crankshaft 16 and the gear transmission 47 is housed as an auxiliary machine, and the clutch 46 is provided with a fan 86. The fan 86 can be increased in size by being provided in 46, and the increase in the number of parts and the number of assembling steps can be suppressed while the blow-by gas is led out from the crank chamber 51 more effectively.

  The clutch outer 61 included in the clutch 46 is pressed and held by the clutch outer 61 so as to be sandwiched between the driven gear 75 constituting a part of the primary reduction device 44 provided between the clutch outer 61 and the crankshaft 16. The presser plate 76 is attached, and a plurality of fins 87, 87... Are integrally formed on the presser plate 76 by press molding to form the fan 86. Therefore, the fan 86 can be easily formed while improving productivity. it can.

  An input shaft 48 of the gear transmission 47 penetrates the partition wall 18 a rotatably and is connected to the clutch inner 63 of the clutch 46 so as not to rotate relative to each other. The communication holes 84 and 85 are provided between the partition wall 18 a and the input shaft 48. Is formed in an arc shape surrounding a part of the ball bearing 55 provided in the fan 86, the communication holes 84 and 85 are made relatively large along the rotation direction of the fan 86, and the blow-by gas is led out from the crank chamber 51 more effectively. As a result, the ventilation performance can be improved.

  Further, a mounting boss provided on the partition wall 18a for mounting a stopper plate 88 for preventing the ball bearing 55 from being detached from the partition wall 18a between at least two communication holes 84 and 85 disposed so as to surround the ball bearing 55. 90 is arranged, it is possible to reinforce the periphery of the communication holes 84 and 85 with the mounting boss 90, and the opening area of the communication holes 84 and 85 can be increased while avoiding a decrease in strength of the partition wall 18a. Further, more effective derivation of blow-by gas from the crank chamber 51 becomes possible.

  Further, an inner cylindrical portion 91 disposed inside the communication holes 84 and 85 and an outer cylindrical portion 92 disposed outside the communication holes 84 and 85 extend toward the inner peripheral portion of the fan 86. Since it is provided in the partition wall 18a, the suction negative pressure of the fan 86 can be effectively applied to the communication holes 84 and 85, and the blow-by gas can be led out from the crank chamber 51 more effectively.

  As the second embodiment of the present invention, as shown in FIG. 9, the return chamber 99 is formed in the lower right part of the front part of the case main body 94 in the traveling direction of the motorcycle. The first connecting pipe 57 may be provided on the upper left part of the front part of the case main body 94.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. Is possible.

DESCRIPTION OF SYMBOLS 11 ... Engine main body 16 ... Crankshaft 17 ... Cylinder bore 18a ... Partition 21 ... Piston 30 ... Intake system 31 ... Air cleaner 37 ... Cleaner element 44 ... Primary deceleration Device 46... Clutch 47 as an auxiliary machine... Gear transmission 48 as a transmission... Input shaft 51... Crank chamber 52. 60 ... New introduction passage 61 ... Clutch outer 63 ... Clutch inner 75 ... Driven gear 76 ... Presser plate 83 ... Blow-by gas return passages 84, 85 ... Communication hole 86 ... -Fan 87 ... Fin 88 ... Stopper plate 90 ... Mounting boss 91 ... Inner cylinder 92 ... Outer cylinder

Claims (6)

  A crank chamber (51) leading to a cylinder bore (17) for slidably fitting the piston (21), and an auxiliary machine (46) linked and connected to a crankshaft (16) connected to the piston (21) And a new introduction passage (60) that is formed in the engine body (11) with a partition wall (18a) interposed therebetween, and guides outside air to the crank chamber (51). The blow-by gas return passage (83) for returning the blow-by gas in the crank chamber (51) to the intake system (30) downstream of the cleaner element (37) provided in the air cleaner (31) is provided in the engine body ( 11) In the blow-by gas ventilation device for an internal combustion engine connected to 11), the crank chamber (51) communicates with the auxiliary machinery chamber (52) communicating with the blow-by gas return passage (83). A communication hole (84, 85) is provided in the partition wall (18a), and gas flows from the crank chamber (51) to the auxiliary machine chamber (52) through the communication hole (84, 85). A blow-by gas ventilating device for an internal combustion engine, wherein a fan (86) to be rotated is disposed in the auxiliary machine chamber (52) so as to rotate in conjunction with the crankshaft (16).   A clutch (46) for connecting / disconnecting power transmission between the crankshaft (16) and the transmission (47) is housed in the auxiliary machine chamber (52) as the auxiliary machine, and the fan (86) The blow-by gas ventilation device for an internal combustion engine according to claim 1, wherein the blow-by gas ventilation device is provided in a clutch (46).   The driven outer gear (75) constituting a part of the primary reduction gear (44) provided between the outer clutch member (61) and the crankshaft (16) is provided on the outer clutch member (61) provided in the clutch (46). A presser plate (76) that is pressed and held so as to be sandwiched between the clutch outer (61) is attached, and a plurality of fins (87) are integrally formed on the presser plate (76) by press molding to form the fan ( 86). The blow-by gas ventilating device for an internal combustion engine according to claim 2, wherein 86) is configured.   An input shaft (48) of the transmission (47) passes through the partition wall (18a) rotatably and is connected to a clutch inner (63) of the clutch (46) in a relatively non-rotatable manner. 85) is formed in an arc shape surrounding a part of a bearing member (55) provided between the partition wall (18a) and the input shaft (48). Blow-by gas ventilator.   A stopper plate (88) for preventing the bearing member (55) from being separated from the partition wall (18a) between at least two communication holes (84, 85) arranged so as to surround the bearing member (55). The blow-by gas ventilating device for an internal combustion engine according to claim 4, wherein a mounting boss (90) provided on the partition wall (18a) is disposed for mounting the engine.   An inner cylinder portion (91) disposed inside the communication hole (84, 85) and an outer cylinder portion (92) disposed outside the communication hole (84, 85) are the fan (86). The blow-by gas ventilation device for an internal combustion engine according to claim 3 or 4, wherein the blow-by gas ventilation device is provided in the partition wall (18a) so as to extend to an inner peripheral portion of the internal combustion engine.

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