VENTILATION STRUCTURE

Abstract

A venting structure comprising a venting device (20A) that subjects an oil-containing gas in a crankcase (5) of an engine (2) to gas / liquid separation, wherein the venting device (20A) includes a venting mounting seat (5a) formed on the crankcase (5) and a venting cover (21) attached to the venting mounting seat (5a) via a sealing element (25), the sealing element (25) integrally contains a dividing element (25e) which divides a venting chamber (20) in the venting device (20A) into a plurality of compartments (20b, 20c), the vent chamber (20) contains a pair of connecting holes (5q, 5r) on both sides in the axial direction of a crankshaft and an intermediate connecting hole (5s) between the pair of connecting holes (5q, 5r), one connection opening (5q) of the pair of connection openings (5q, 5r) is connected to a rotary machine chamber (41), and the other connection opening (5r) of the pair of connection openings (5q, 5r) is connected to a clutch chamber (42), the intermediate connection opening (5s) communicates with a gear chamber (3A) of the crankcase (5), and the pair of connecting holes (5q, 5r) and the intermediate connecting hole (5s) are arranged in the compartment (20c) below the sealing member (25).

Description

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority based on Japanese Patent Application No. 2021-060149, filed on March 31, 2021. BACKGROUND OF THE INVENTIONField of the invention

[0002] The present invention relates to a venting structure. Description of related technology

[0003] In the related art, a vent structure is known in which an upper portion of a crankcase of an engine (internal combustion engine) is covered with a vent cover to form a vent chamber (see, for example, Japanese Unexamined Patent Application, First Publication JP H10-54219 A). The vent structure is divided into multiple compartments and constitutes a gas / liquid separation chamber.

[0004] DE 10 2019 118 204 A1 discloses a venting structure including a venting device that subjects an oil-containing gas in a crankcase of an engine to gas / liquid separation. The venting device includes a vent mounting seat formed on the crankcase and a vent cover attached to the vent mounting seat via a sealing member. The sealing member integrally includes a partitioning member that divides a vent chamber in the venting device into a plurality of compartments. Similar venting structures are shown in DE 101 08 771 B4 and EP 3 153 679 B1. SUMMARY OF THE INVENTION

[0005] The vent structure in JP H10-54219 A technique includes separate partition plates to separate the majority of compartments in the vent chamber and has a problem in the increase in the number of parts.

[0006] An object of one aspect of the present invention is to effectively reduce the number of parts in a ventilation structure in which a ventilation chamber is formed in a crankcase of an engine.

[0007] In order to achieve the above object, a vent structure according to claim 1 is provided.

[0008] Since the partition member that divides the breather chamber into the plurality of compartments is formed integrally with the sealing member that seals between the crankcase and the breather cover, it is possible to reduce the number of separate partition members that divide the breather chamber and effectively reduce the number of parts.

[0009] Since the breather chamber (20) includes a pair of communication ports on both sides in the axial direction of a crankshaft, and one communication port of the pair of communication ports communicates with a rotating machine chamber, and the other communication port of the pair of communication ports communicates with a clutch chamber, it is possible to minimize pressure fluctuations in the rotating machine chamber and the clutch chamber, and to perform gas / liquid separation of gas containing oil discharged from the rotating machine chamber and the clutch member.

[0010] Since the breather chamber includes an intermediate communication port at a position below the pair of communication ports between the pair of communication ports, and the intermediate communication port can communicate with the transmission chamber of the crankcase, after a gas that has entered the breather chamber through the pair of communication ports is subjected to gas / liquid separation, the separated oil can be returned to the transmission chamber through the intermediate communication port.

[0011] According to claim 4, the plurality of compartments of the vent chamber may be an upper chamber and a lower chamber which are divided in the up-down direction by means of the dividing member.

[0012] This makes it possible to effectively promote gas / liquid separation through the upper and lower chambers by means of an ascending air flow from the gas heated in the crankcase.

[0013] According to claim 5, the sealing member may be arranged inclined with respect to a horizontal direction, and an inclined lower end portion of the partition member may include partition communication holes through which oil flows from the upper chamber to the lower chamber.

[0014] This makes it possible to promote the circulation of the oil separated in the upper chamber of the venting chamber by allowing the oil to flow by itself through the dividing connection hole to the lower chamber.

[0015] According to claim 5, a plurality of partition connection holes may be provided, and the vent cover may include a rib that performs a separation between the plurality of partition connection holes.

[0016] This allows the rib of the breather cover to easily guide oil flow to each division connection hole.

[0017] According to claim 6, the partition connection holes may be arranged in corner portions formed by a lid peripheral wall of the vent lid and the rib or a projection part connected to the lid peripheral wall of the vent lid.

[0018] This allows the oil in the upper chamber to flow effectively to the lower chamber through the partition connection hole in the corner portions where oil tends to accumulate.

[0019] According to claim 8, the rib in the venting chamber can form a labyrinth structure.

[0020] As a result, the rib of the vent cap facilitates the formation of the labyrinth structure and the gas / liquid separation chamber can be represented while reducing the number of parts.

[0021] According to claim 9, an upper cover wall of the vent cover can be curved so that it follows an outer peripheral shape of a starter motor arranged above the upper cover wall.

[0022] This allows free space around the starter motor to be used effectively to ensure maximum capacity for the venting chamber.

[0023] According to the invention, in a breather structure in which a breather chamber is formed in a crankcase of an engine, it is possible to effectively reduce the number of parts. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a left side view showing a drive unit in an embodiment of the present invention. Fig. 2 is a top view of the drive unit. Fig. 3 is a plan view in a state where a starter motor of Fig. 2 away. Fig. 4 is a plan view of a venting device of the drive unit. Fig. 5 is a plan view of a state in which a vent cap of Fig. 4 away. Fig. 6 is a perspective view of a vent mounting seat of the venting device as viewed from an upper right rear side. Fig. 7 is a perspective view of the vent mounting seat as viewed from an upper left rear side. Fig. Figure 8 is a plan view of a seal of the venting device. Fig. 9 is a plan view including a cross section of the vent cover of the venting device. Fig. 10 is a cross-sectional view along line XX of Fig. 4. Fig. 11 is a cross-sectional view along line XI-XI of Fig. 4. Fig. 12 is a cross-sectional view along line XII-XII of Fig. 10. Fig. 13 is a cross-sectional view along line XIII-XIII of Fig. 12. DESCRIPTION OF THE VERSIONS

[0024] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Directions such as front direction, rear direction, left direction, and right direction in the following description correspond to directions in a vehicle in which a power unit 1 is installed, as described later, unless otherwise stated. Further, at appropriate locations in the drawings used in the following description, an arrow FR indicating the front direction of the vehicle, an arrow LH indicating the left direction of the vehicle, and an arrow UP indicating an upward direction of the vehicle are indicated. <antriebseinheit>

[0025] As in Fig. 1, the drive unit 1, which is installed integrally in a ride-on vehicle, includes an engine 2, which is a drive source, and a transmission 3, which is arranged behind the engine 2.

[0026] Engine 2 is a water-cooled, four-stroke, inline two-cylinder internal combustion engine, with two cylinders arranged horizontally in the width direction of the vehicle. The crank phase angle between the two cylinders is 180°, 270°, or the like, instead of 360°. This means that the pistons of the two cylinders reciprocate at different times.

[0027] The engine 2 includes a crankcase 5, a cylinder part 6 extending diagonally forward and upward from a front portion of the crankcase 5, and an oil pan 7 attached to a lower portion of the crankcase 5. A crankshaft 11 extending in the vehicle width direction (left-right direction of the vehicle) is housed in the crankcase 5. That is, an axial direction of the crankshaft 11 (axial direction of a crank) is parallel to the vehicle width direction. Line C in the drawings indicates a cylinder axis in a direction in which the cylinder part 6 stands upright.

[0028] The cylinder part 6 is configured such that a cylinder block 6a, a cylinder head 6b, and a head cover 6c overlap each other in this order from the crankcase 5 side. The cylinder block 6a and the cylinder head 6b are integrally fixed to the crankcase 5. The cylinder block 6a may be integrally formed with the crankcase. An intake device (not shown) is connected to a rear portion of the cylinder head 6b, and an exhaust device (not shown) is connected to a front portion of the cylinder head 6b.

[0029] Together with regard to the Fig. 12 and Fig. 13, a rear portion of the crankcase 5 serves as a transmission case configured to accommodate the transmission 3. The transmission 3 includes a main shaft 12 and a counter shaft 13 parallel to the crankshaft 11, and a transmission gear group (no reference numerals) supported across the two shafts 12 and 13.

[0030] A starter motor 15 is arranged above the crankcase 5 and behind the cylinder block 6a. A generator 17, which is arranged on the left side of the crankshaft 11, is accommodated in a side section of the crankcase on one side (left side) in the vehicle width direction. A generator cover 8, with which the generator 17 is covered, is attached to a left side section of the crankcase 5. A right cover 9, with which the area above a right side section of the transmission housing is covered, is attached to a right side section of the crankcase 5. The right cover 9 also serves as a clutch cover, with which a clutch 18 is covered.

[0031] Also with respect to Fig. 2, the starter motor 15 is arranged so that its drive shaft is aligned in the width direction of the vehicle and has a cylindrical outer shape with the drive shaft of the starter motor 15 located at the center. It is arranged near an upper surface portion of the crankcase 5. The starter motor 15 is attached to a starter gear case 16, the left end portion of which protrudes beyond the left side portion of the crankcase 5. A pair of motor lands 15a extending in the right direction are provided on the right side portion of the starter motor 15, and distal end portions of these motor lands 15a are fixed to an upper wall portion of the crankcase 5.In the drawings, a pair of left and right inlet system connection parts, which are configured to connect the inlet device (not shown) to the rear section of the cylinder head 6b, are denoted by the reference sign 6d, and a tensioner fixing part, which is configured to attach a control chain tensioner to the left rear side of the cylinder block 6a, is denoted by the reference sign 6e. <Ventilation device>

[0032] In relation to the Fig. 3, Fig. 4, Fig. 10 and Fig. Below the starter motor 15, an air venting device 20A is provided, which is configured to absorb pressure fluctuations in the crankcase 5. The air venting device 20A includes an air venting mounting seat 5a formed at the upper section of the crankcase 5, and an air venting cover 21 attached to the air venting mounting seat 5a via a seal 25. The air venting device 20A has an outer shape that is longer in the vehicle width direction than in the front-rear direction and the up-down direction. The air venting device 20A has a shape in which, when viewed from above, a rear left side of a horizontally long ellipse as an approximate outer shape is set back forward.

[0033] The breather cover 21 is attached to the breather mounting seat 5a of the crankcase 5 with a plurality of bolts B1. When the breather mounting seat 5a and the breather cover 21 are attached, a breather chamber 20 is formed therein, which is closed from the outside. The breather chamber 20 receives an oil-containing gas (blow-by gas, oil mist-containing gas, and the like) from the crankcase 5 to absorb pressure fluctuations within the crank chamber. The breather chamber 20 constitutes a gas-liquid separation chamber configured to separate oil from the oil-containing gas. <Entlüftungsbefestigungssitz>

[0034] Regarding the Fig. 5 to 7, a breather mounting seat 5a is formed to protrude further upward from the upper portion of the crankcase 5 than a peripheral portion. The breather mounting seat 5a forms an upper surface (seat surface) 5b along a forwardly inclined reference plane K (see Fig. 10 and Fig. 11). The upper surface 5b is formed in a frame shape in which the upper surface 5b extends along peripheral edges of a plurality of opening portions 5g, 5m, and 5n. A frame-shaped lower surface 21n of the breather cover contacts the upper surface 5b via the sheet-shaped gasket 25. In this state, when the breather cover 21 is attached to the breather attachment seat 5a, the breather device 20A is mounted on the upper surface portion of the crankcase 5.

[0035] How together in relation to the Fig. 10 and Fig. 11, the upper surface 5b of the breather mounting seat 5a is formed parallel to mating surfaces of the crankcase 5 and the cylinder block 6a. The mating surfaces are planes that are orthogonal to a cylinder axis C when viewed in side view of the vehicle (see Fig. 1). The lower surface 21n of the vent cover 21 and the flat gasket 25 are also inclined in the same manner as the upper surface 5b of the vent mounting seat 5a. That is, the vent device 20A is inclined forward as a whole.

[0036] Regarding the Fig. 5 and Fig. 7, the vent fixing seat 5a includes a fixing seat peripheral wall 5d extending along an outer periphery of the vent fixing seat 5a when viewed in plan view, a plurality of boss portions 5c provided at specific portions of the fixing seat peripheral wall 5d, a first fixing seat rib 5e extending over a pair of boss portions 5c between the opening portions 5g and 5m, and a second fixing seat rib 5f extending over a pair of boss portions 5c between the opening portions 5g and 5n.

[0037] The fastening seat peripheral wall 5d is arranged so that the fastening seat peripheral wall 5d and a cover peripheral wall 21a (see Fig. 4) of the vent cover 21, when viewed in plan view. A lower end surface (lower surface 21n) of the cover peripheral wall 21a of the vent cover 21 comes into contact with an upper end surface (upper surface) 5b of the mounting seat peripheral wall 5d via the gasket 25.

[0038] A threaded hole for screwing each of the bolts B1 is formed in each of the hub parts 5c.

[0039] The first fixing seat rib 5e is formed in a straight line in which the first fixing seat rib 5e extends in the width direction of the vehicle.

[0040] The second mounting seat rib 5f is formed in an L-shape when viewed from a top view. The second mounting seat rib 5f integrally includes a vertical rib 5f1 extending forward from the boss portion 5c at a right rear side of the vent mounting seat 5a, and a horizontal rib 5f2 extending from the boss portion 5c to a left side at a right end of the vent mounting seat 5a.

[0041] A first passage portion 5m passing through the upper surface portion of the crankcase 5 in the up-down direction is formed at a left rear portion of the breather mounting seat 5a and between the mounting seat peripheral wall 5d and the first mounting seat rib 5e.

[0042] A second passage portion 5n passing through the upper surface portion of the crankcase 5 in the up-down direction is formed at a right rear portion of the breather mounting seat 5a and surrounded by the mounting seat peripheral wall 5d and the second mounting seat rib 5f.

[0043] The first passage section 5m and the second passage section 5n open the inside of the crankcase 5, in particular the transmission chamber 3a, into the ventilation chamber 20.

[0044] Fig. 5 shows that gear wheels 27 and 28 arranged in the gear chamber 3a are visually recognizable through the first passage portion 5m and the second passage portion 5n when viewed in plan view (upper view) of the vent mounting seat 5a.

[0045] The vent mounting seat 5a includes the opening portions 5g having a bottom wall part 5p at a portion inside the mounting seat peripheral wall 5d except for the first passage portion 5m and the second passage portion 5n.

[0046] Regarding the Fig. 5 and Fig. 6, a first communication hole (communication hole) 5q is formed under an end portion (left end portion) on one side of the mounting seat peripheral wall 5d in the width direction of the vehicle.

[0047] Also with regard to Fig. 12, the first communication port 5q communicates with a generator chamber (rotary machine chamber) 41 in which the generator 17 is housed. The generator 17 is arranged coaxially with the crankshaft 11 and generates electricity when the crankshaft 11 rotates. The generator chamber 41 of the generator 17 is formed on the left side portion of the crankcase 5.

[0048] Regarding the Fig. 5 and Fig. 7, a second communication hole (communication hole) 5r is formed under one end portion (right end portion) on the other side in the width direction of the vehicle of the mounting seat peripheral wall 5d.

[0049] Also with regard to Fig. 12, the second communication port 5r communicates with a clutch chamber 42 in which the clutch 18 is housed. The clutch 18 is arranged coaxially with the main shaft 12 and disconnects the power transmission between the engine 2 and the transmission 3. The clutch chamber 42 is formed on the right side portion of the crankcase 5.

[0050] In relation to Fig. 5, a third connection opening (intermediate connection opening) 5s is formed between the first connection opening 5q and the second connection opening 5r of the bottom wall part 5p.

[0051] Together in relation to Fig. 12 and Fig. 13, the third communication port 5s communicates with the transmission chamber 3a (or the oil pan 7) formed at the rear portion of the crankcase 5.

[0052] A vent passage 40 extending in the width direction of the vehicle is formed in a lower portion of the vent mounting seat 5a.

[0053] In relation to Fig. 12, in the breather passage 40, one side (left side) of the engine 2 in the vehicle width direction opens to the generator chamber 41 via the first communication port 5q, and the other side (right side) of the engine 2 in the vehicle width direction opens to the clutch chamber 42 via the second communication port 5r.

[0054] Regarding the Fig. 5 and Fig. 7, the first communication port 5q and the second communication port 5r are arranged near a bottom portion of the vent mounting seat 5a. Therefore, it is difficult for oily gas that has entered the vent chamber 20 through the first communication port 5q and the second communication port 5r to enter an exhaust pipe 23 (see Fig. 4) side of the vent cover 21. <Entlüftungsdeckel>

[0055] Regarding the Fig. 4 and Fig. 9, the vent lid 21 integrally includes the lid peripheral wall 21a, which forms the contour of the vent device 20A shown in plan view, and an upper lid wall 21r, which closes an upper end side of the lid peripheral wall 21a.

[0056] The cover peripheral wall 21a is a portion having, when viewed in plan view, the same shape or substantially the same shape as the mounting seat peripheral wall 5d of the breather mounting seat 5a of the crankcase 5, and includes a plurality of boss portions (projection portions) 21f. Each of the boss portions 21f has a bolt through hole through which each of the bolts B1 is inserted. Each of the boss portions 21f is fixed to each of the boss portions 5c of the breather mounting seat 5a with each of the bolts B1.

[0057] The breather cover 21 includes a pipe connecting part 21b that protrudes diagonally toward the right rear side at a right rear end portion of the cover peripheral wall 21a. The exhaust pipe 23, which enables the discharge of gas separated from the oil in the breather chamber 20, is connected to the pipe connecting part 21b. The exhaust pipe 23 is connected to an air cleaner of the intake device via a hose or the like (not shown). The gas that has undergone gas / liquid separation in the breather chamber 20 is guided from the air cleaner to the combustion chamber of the engine 2.

[0058] The vent lid 21 includes a front rib (rib) 21c extending from the lid peripheral wall 21a to an inner side of the vent lid 21, a rear rib 21d, a side rib 21e1 and another side rib 21e2.

[0059] The front rib 21c extends rearward from a front end portion 21h of the lid peripheral wall 21a. A concave groove 21c1 is formed on an upper surface side of the lid upper wall 21r such that the concave groove 21c1 and the front rib 21c overlap when viewed in plan view.

[0060] The rear rib 21d extends forward from a rear end portion 21j of the lid peripheral wall 21a. A concave groove 21d1 is formed on the upper surface of the lid upper wall 21r such that the concave groove 21d1 and the rear rib 21d overlap when viewed in plan view. The rear rib 21d is disposed on the vertical rib 5f1 of the second fixing rib 5f of the vent fixing seat 5a via the gasket 25. The rear rib 21d extends further forward than the vertical rib 5f1. A partition member 25e of the gasket 25, described later, is disposed between the rear rib 21d and the vertical rib 5f1.

[0061] The one side rib 21e1 is located on a side end portion (left end portion) side of the vent cover 21. The one side rib 21e1 extends from a side edge portion 21k1 on one side (left side) in the left-right direction to the other side (right side) in the left-right direction of the cover peripheral wall 21a to extend between the pair of boss parts 21f. The one side rib 21e1 extends parallel to the width direction of the vehicle. A standing wall part 21e3 for forming a lower part 21s described later in a stepped shape is formed on the left side of the cover upper wall 21r. On the lower part 21s side, immediately behind a lower end portion of the standing wall part 21e3, a concave groove 21e4 extending in the width direction of the vehicle is formed.The concave groove 21e4 is arranged such that the concave groove 21e4 and the one side rib 21e1, when viewed in plan view (see . Fig. 10) overlap.

[0062] The other side rib 21e2 is located on the other side end portion (right end portion) side of the vent lid 21. The other side rib 21e2 extends parallel to the width direction of the vehicle from a side edge portion 21k2 of the other side (right side) in the left-right direction of the lid peripheral wall 21a to the one side (left side) in the left-right direction. The other side rib 21e2 is arranged such that the horizontal rib 5f2 (see Fig. 5) of the second fixing seat rib 5f of the vent fixing seat 5a and the other side rib 21e2 overlap when viewed in plan view.

[0063] A channel 21m configured to connect opening portions 5g to the second passage portion 5n is formed, for example, in the upper portion of the right end portion of the other side rib 21e2. The channel 21m is formed to cut out a right upper portion of the other side rib 21e2. A concave groove 21e5 is formed on the upper surface side of the upper lid wall 21 such that the concave groove 21e5 and a portion of the other side rib 21e2, except for the channel 21m, overlap when viewed in plan view.

[0064] A front bulge part 21p and a bulge part 21q, which are arranged adjacent to each other in the front-rear direction and are bulged upward, are provided at a right side portion of the vent cover 21.

[0065] Regarding the Fig. 10 and Fig. 13, the upper cover wall 21r is disposed at a distance below the starter motor 15 and has a curved shape in which the upper cover wall 21r extends along a cylindrical outer wall of the starter motor 15. Thus, the capacity of the vent chamber 20 can be ensured as much as possible by utilizing a dead space formed around the cylindrical shape of the starter motor 15.

[0066] Here, the pair of boss portions 21f at the front end portion 21h of the lid peripheral wall 21a are defined in order from the left side as boss portions 21f1 and 21f2, and a boss portion 21f immediately in front of a rear concave shape of the lid peripheral wall 21a is defined as boss portion 21f3. Further details will be apparent from the following description.

[0067] In relation to Fig. 9, on a path from an inlet (first seal opening part 25e, which will be described later) of the upper chamber 20b to the outlet pipe 23, the boss part 21f1, the boss part 21f2, the front rib 21c, the rear rib 21d, and the boss part 21f3, which are arranged in sequence from an upstream side, form a labyrinth channel 30.

[0068] This labyrinth channel 30 can improve the gas / liquid separation effect of the oil-containing gas in the vent chamber 20.

[0069] In relation to Fig. 12, the vent fixing seat 5a includes the plurality of boss portions 5c and the first fixing seat rib 5e for connecting among the boss portion 21f1, the boss portion 21f2, the front rib 21c, and the boss portion 21f3 of the vent cover 21, respectively. The plurality of boss portions 5c and the first fixing seat rib 5e protrude into the vent passage 40, and the vent passage 40 serves as a channel that meanders forward and backward. This structure also improves the gas-liquid separation effect in the vent chamber 20.

[0070] Here, a gas flow in the venting chamber 20 is determined with respect to the Fig. 5 and Fig. 9. The oil-containing gas generated in the crankcase 5 tends to escape from the crankcase 5 in response to pressure fluctuations or the like in the crankcase 5. This gas is introduced into the vent chamber 20 through the first communication port 5q and the second communication port 5r via the generator chamber 41 and the clutch chamber 42.

[0071] The gas introduced into the vent chamber 20 first enters the lower chamber 20c to expand and cool, and then enters the upper chamber 20b through the first seal opening part 25b described later. The gas that has entered the upper chamber 20b flows through the upper chamber 20b from one side (right side) in the vehicle width direction to the other side (right side) and flows through the labyrinth channel 30 formed in the upper chamber 20b to promote gas-liquid separation. The gas that has reached the other side of the upper chamber 20b in the vehicle width direction is introduced into the second passage portion 5n through the channel 21n formed in the other side rib 21e2 and is sent to the air cleaner of the intake device through the exhaust pipe 23 or the like. <dichtung>

[0072] In relation to Fig. 5, Fig. 8 and Fig. 9, the gasket 25 integrally includes a frame-shaped sealing part 25s disposed between the upper surface 5b of the vent mounting seat 5a and the lower surface 21n of the vent cover 21, and the partition member 25 configured to divide the vent chamber 20 into upper and lower compartments (upper chamber 20b and lower chamber 20c). Fig. In the seal 25 shown in Figure 8, the dividing element 25e is shaded.

[0073] The sealing part 25s includes a peripheral edge portion 25a along the contour of the vent device 20A (this is also the contour of the vent fixing seat 5a and the vent cover 21) when viewed in plan view, and a first rib-facing part 25ae and a second rib-facing part 25af along the first fixing seat rib 5e and the second fixing seat rib 5f of the vent fixing seat 5a. The second rib-facing part 25af includes a vertical rib-facing part 25af1 and a horizontal rib-facing part 25af corresponding to the vertical rib 5f1 and the horizontal rib 5f2 of the fixing seat rib 5f.

[0074] The gasket 25 includes the first gasket opening part 25b opening in front of the vent chamber 20 on one side (left side) in the vehicle width direction, and a second gasket opening part 25c opening behind the vent chamber 20 on one side (left side) in the vehicle width direction. The first rib-facing part 25ae extending in the vehicle width direction is provided between the first gasket opening part 25b and the second gasket opening part 25c.

[0075] The peripheral edge portion 25a includes a plurality of bolt insert parts 25d in which each of the boss parts 5c of the vent fixing seat 5a and each of the boss parts 21f of the vent cover 21 overlap when viewed in plan view.

[0076] The first seal opening part 25b is formed such that the first seal opening part 25b and a left side portion of the opening portion 5g of the vent mounting seat 5a overlap when viewed in plan view. The first seal opening part 25b communicates with upper and lower compartments (upper chamber 20b and lower chamber 20c) divided by the seal 25 in the vent chamber 20.

[0077] The second seal opening part 25c is formed such that the second seal opening part 25c and the first passage portion 5m of the vent mounting seat 5a overlap when viewed in plan view. The lower part 21s, in which the lower part 21s, the first passage portion 5m, and the second seal opening part 25c overlap when viewed in plan view, is formed on the upper lid wall 21r of the vent lid 21. The lower part 21s is arranged offset downward (toward the vent lid 21 side) with respect to the remaining portion of the upper lid wall 21a. The lower part 21s causes the upper chamber 20b to be removable or reduced in size in an area where the lower part 21s and the upper chamber 20b overlap when viewed in plan view.

[0078] Although the second seal opening part 25c opens the gear chamber 3a upward through the first passage portion 5m, the lower part 21s of the vent cover 21 faces the second seal opening part 25c from above. Thus, communication between the gear chamber 3a and the upper chamber 20b through the second seal opening part 25c is prevented.

[0079] In relation to Fig. 8, the gasket 25 includes the partition member 25e configured to partition the vent chamber 20 in the up-down direction in a region inside the peripheral edge portion 25a by avoiding each of the rib-facing parts 25ae and 25af and each of the opening parts 25b and 25c.

[0080] Although the partition member 25e is distinguished from the peripheral edge 25a and each of the rib-facing parts 25ae and 25af by shading and chain lines, they are integrally formed, for example, by cutting out an integrated flat plate-like material into a prescribed shape.

[0081] The dividing element 25e includes a first dividing element 25f and a second dividing element 25g.

[0082] The first partition member 25f is a part in which the first partition member 25f and the opening portions 5g (see Fig. 5) of the vent fixing seat 5a when viewed in plan view, except for the first seal opening part 25b.

[0083] The second partition member 25e is a part in which the second partition member 25g and the second passage portion 5m (see Fig. 5) of the vent mounting seat 5a overlap when viewed in plan view.

[0084] In a front edge portion of the first partition member 25f, a pair of left and right partition communication holes 25m and 25n are formed, which are configured to communicate the upper chamber 20b and the lower chamber 20c partitioned by the gasket 25.

[0085] The front rib 21c of the breather cover 21 is disposed between the pair of partition communication holes 25m and 25n. The front rib 21c blocks gas flow in the upper chamber 20b in the vehicle width direction and allows the oil separated in the upper chamber 20b to easily flow into the partition communication holes 25m and 25n. Thus, the oil that has undergone gas-liquid separation can be effectively caused to drip into the lower chamber 20c through the partition communication holes 25m and 25n.

[0086] In relation to Fig. 9, one 25m of the partition connection holes of the gasket 25 is located on the right side and behind a corner portion (corner portion) 21x on one side formed by the front end portion 21h of the lid peripheral wall 21a around the boss part 20f, which has a front end portion 21h on one side (left side) in the vehicle width direction. The other 25 of the partition connection holes of the gasket 25 is located on the right side and behind a corner portion (corner portion) 21y on the other side formed by the front end portion 21h of the lid peripheral wall 21a and the front rib 21c.

[0087] In this way, the partition connection holes 25m and 25n are arranged separately in the corner portions 21x and 21y of the vent cover 21, respectively. In the embodiment, the term "is arranged in the corner portion" means that the partition connection hole is in contact with the two sides constituting the corner portion, or at least a part of the partition connection hole is arranged within the radius of the rounding of the corner portion.

[0088] Regarding the Fig. 10 and Fig. 11, the seal 25 is inclined such that its front side is lower than its rear side. For this reason, the oil on the seal 25 is easily guided to the pair of partition connection holes 25m and 25n. Specifically, oil is easily collected in the corner portion 21x on one side and the corner portion 21y on the other side, as described above. Thus, in a vehicle in which the vehicle body rolls during travel, the pair of partition connection holes 25m and 25n allows the oil to effectively drip into the transmission chamber 3a.

[0089] In relation to Fig. 8, the sealing part 25s of the gasket 25 has a function of sealing between the mounting seat peripheral wall 5d, the first mounting seat rib 5e, and the second mounting seat rib 5f of the vent mounting seat 5a, and the cover peripheral wall 21a, the first rib-facing part 25ae, and the second rib-facing part 25af of the vent cover 21. The partition member 25e of the gasket 25 has a function of dividing the vent chamber 20 into upper and lower compartments.

[0090] Together with regard to the Fig. 10, Fig. 11 and Fig. 13, the breather device 20A closes an upper surface opening of the breather mounting seat 5a formed in the upper portion of the crankcase 5 by covering the upper surface opening with the breather cover 21 attached via the gasket 25. The breather device 20A is divided by the gasket 25 into the upper chamber 20f formed in the breather cover 21 and the lower chamber 20c formed below the upper chamber 20b in the breather mounting seat 5a. The upper chamber 20b and the lower chamber 20c are divided by the partition member 25e integrally included in the gasket 25.

[0091] The above-described gasket 25 is a sealing member that seals between the upper portion of the crankcase 5 and the breather cover 21, but is also a partitioning member that divides the breather chamber 20 into the upper chamber 20b and the lower chamber 20c. When the gasket 25 also serves as a partitioning member of the breather chamber 20, it is possible to eliminate the need for a separate member (or reduce the number of separate members) to divide the breather chamber 20, and it becomes possible to reduce the number of parts. Furthermore, when the breather chamber 20 is divided in the up-down direction by means of the gasket 25, the oil mist and gas heated in the crankcase can be easily conducted from the lower chamber 20c to the upper chamber 20b, and it becomes possible to effectively promote gas-liquid separation by means of the upper and lower chambers.

[0092] Regarding the Fig. 5, Fig. 9 and Fig. 13, the third communication port 5s is formed in an intermediate portion (not limited to a central portion) of a lower surface portion 40a of the breather duct 40 in the vehicle width direction. A recessed portion 40b, which is recessed downward with respect to the remaining portion of the lower surface portion 40a, is formed around the third communication port 5s. Thus, the oil collected on the lower surface portion 40a is easily guided to the third communication port 5s.

[0093] In relation to Fig. 13, the crankcase 5 includes an upper case 5x and a lower case 5y, which are divided in the up-down direction. The upper case 5x and the lower case 5y are fastened with a plurality of bolts B2.

[0094] An upper case communication passage 5v, formed in the upper case 5x and extending in the up-down direction, is connected below the third communication opening 5s. A lower case communication passage 5w, formed in the lower case 5y and extending in the up-down direction, is connected below the upper case communication passage 5v. A lower end of the lower case communication passage 5w opens into the transmission chamber 3a (or the oil pan 7).

[0095] As explained above, the breather structure in the above-described embodiment is a breather structure including the breather device 20A that subjects an oily gas (oil mist, unburned gas) of the crankcase 5 of the engine 2 to gas / liquid separation, the breather device 20A including the breather mounting seat 5a formed in the upper portion of the crankcase 5 and the breather cover 21 attached to the breather mounting seat 5a via the gasket 25, and the gasket 25 integrally forms the partition member 25e that divides the breather chamber 20 into the plurality of compartments (the upper chamber 20b and the lower chamber 20c).

[0096] According to this structure, the partition member 25e for dividing the breather chamber 20 into the upper chamber 20b and the lower chamber 20c is integrally formed on the gasket 25 that seals between the crankcase 5 and the breather cover 21. Thus, it becomes possible to reduce the number of separate partition members for dividing the breather chamber 20 and effectively reduce the number of parts.

[0097] Also, in the above-described breather structure, the breather chamber 20 includes the pair of first communication ports 5q and second communication ports 5r on both sides of the lower chamber 20c in the vehicle width direction, the first communication port 5q communicating with the generator chamber 41 on one side of the crankcase 5 in the vehicle width direction, and the second communication port 5r communicating with the clutch chamber 42 on the other side of the crankcase 5 in the vehicle width direction. Thus, it is possible to minimize pressure fluctuations of the generator chamber 41 and the clutch chamber 42, and to subject oily gas discharged from the generator chamber 41 and the clutch chamber 42 to gas-liquid separation.

[0098] Furthermore, in the above-described venting structure, the venting chamber 20 includes the third communication port 5s at a position lower than the pair of the first communication port 5q and the second communication port 5r between the first communication port 5q and the second communication port 5r, and the third communication port 5s communicates with the transmission chamber 3a in the rear portion of the crankcase 5. Thus, the gas that has entered the venting chamber 20 through the pair of the first communication port 5q and the second communication port 5r undergoes gas-liquid separation, and then the separated oil can be returned to the transmission chamber 3a through the third communication port 5s.

[0099] In the above-described venting structure, the venting chamber 20 is divided in the up-down direction by the partition member 25e to form the upper chamber 20b and the lower chamber 20e. Thus, it becomes possible to effectively promote gas-liquid separation through the upper and lower chambers by means of an ascending airflow of the gas heated in the crankcase.

[0100] In the above-described vent structure, the gasket 25 is arranged inclined with respect to the horizontal direction, and the partition communication holes 25m and 25n through which the oil in the upper chamber 20b flows to the lower chamber 20c are provided at the front end portion, which is the inclined lower end portion of the partition member 25e. Thus, the oil in the upper chamber 20b in the vent chamber 20 can flow into the lower chamber 20c by itself through the partition communication holes 25m and 25n to promote oil circulation.

[0101] In the above-described vent structure, the plurality of partition connection holes 25m and 25n are provided, and the vent cover 21 includes the front rib 21c separating the plurality of partition connection holes 25m and 25n. Thus, the front rib 21c of the vent cover 21 can easily guide the oil flow to each of the partition connection holes 25m and 25n.

[0102] In the above-described breather structure, the partitioning communication holes 25m and 25n are separately arranged in the corner portion 21x on one side and the corner portion 21y on the other side, which are formed by the lid peripheral wall 21a of the breather lid 21 and the front rib 21c or the boss portions 21f connected to the lid peripheral wall 21a of the breather lid 21. Thus, in the corner portion 21x on one side and the corner portion 21y on the other side, where the oil is easily collected, the oil in the upper chamber 20b can effectively flow into the lower chamber 20c through the partitioning communication holes 25m and 25n.

[0103] In the vent structure described above, the front rib 21c forms a labyrinth structure in the vent chamber 20. Thus, the front rib 21c of the vent cover 21 can easily form a labyrinth structure and constitute the gas / liquid separation chamber while reducing the number of parts.

[0104] In the above-described breather structure, the upper cover wall 21r of the breather cover 21 is curved to follow an outer peripheral shape of the starter motor 15 mounted on the upper portion of the crankcase 5. Thus, a clearance around the starter motor 15 can be effectively utilized to ensure the capacity of the breather chamber 20 as much as possible.

[0105] The present invention is not limited to the above embodiment. For example, although the gasket divides the vent chamber 20 in the up-down direction, the gasket may also divide the vent chamber 20 in a direction other than the up-down direction (left-right direction, front-back direction, or the like).

[0106] Although the partition member 25e of the gasket 25 is formed continuously with the seal part 25s, a rib or an uneven shape may also be provided on the partition member 25e, for example, or the thickness may be varied. Furthermore, the partition member 25e may be a separate member from the seal part 25s and may be bonded to the seal part 25s by an adhesive or the like.

[0107] The power unit including the vent structure in the embodiment can also be applied to a saddle-type vehicle other than a motorcycle. The saddle-type vehicle includes all vehicles in which a rider sits straddling a vehicle body, and includes not only motorcycles (including mopeds and scooter-type vehicles), but also three-wheeled vehicles (including vehicles with two front wheels and one rear wheel, in addition to vehicles with one front wheel and two rear wheels) or four-wheeled vehicles. Furthermore, the present invention can also be applied to vehicles other than saddle-type vehicles (passenger cars, buses, trucks, and the like). The present invention can also be applied to vehicles that include electric motors as prime movers.

[0108] The engine is not limited to a horizontal arrangement in which the crankshaft is arranged in the width direction of the vehicle, but can also be a vertical arrangement in which the crankshaft is arranged in the front-rear direction of the vehicle. Furthermore, the ventilation structure in the embodiment is not limited to vehicle applications, but can also be applied to various transportation devices such as aircraft and ships, and various vehicles and moving bodies such as construction machinery and industrial machinery.

[0109] Also, the structure in the embodiment described above is an example of the present invention, and various modifications such as replacing the components of the embodiment with components known per se are possible without departing from the spirit of the present invention.

[0110] This breather structure is a breather structure comprising a breather device (20A) that subjects an oily gas in a crankcase (5) of an engine (2) to gas / liquid separation, the breather device (20A) including a breather mounting seat (5a) formed on the crankcase (5) and a breather cover (21) attached to the breather mounting seat (5a) via a sealing member (25), and the sealing member (25) integrally including a partition member (25e) that divides a breather chamber (20) in the breather device (20A) into a plurality of compartments (20b, 20c).< / dichtung> < / antriebseinheit>

Claims

[1] A venting structure comprising a venting device (20A) that subjects an oil-containing gas in a crankcase (5) of an engine (2) to gas / liquid separation, wherein the venting device (20A) includes a venting mounting seat (5a) formed on the crankcase (5) and a venting cover (21) attached to the venting mounting seat (5a) via a sealing element (25), the sealing element (25) integrally contains a dividing element (25e) which divides a venting chamber (20) in the venting device (20A) into a plurality of compartments (20b, 20c), the vent chamber (20) contains a pair of connecting holes (5q, 5r) on both sides in the axial direction of a crankshaft and an intermediate connecting hole (5s) between the pair of connecting holes (5q, 5r), one connection opening (5q) of the pair of connection openings (5q, 5r) communicates with a rotary machine chamber (41), and the other connection opening (5r) of the pair of connection openings (5q, 5r) communicates with a clutch chamber (42), the intermediate connection opening (5s) communicates with a gear chamber (3A) of the crankcase (5), and the pair of connecting holes (5q, 5r) and the intermediate connecting hole (5s) are arranged in the compartment (20c) below the sealing member (25). [2] The ventilation structure according to claim 1, wherein the pair of communication ports (5q, 5r) each allowing the rotary machine chamber (41) to communicate with the ventilation chamber (29) is formed in the crankcase (5). [3] The vent structure according to claim 1 or 2, wherein the vent chamber (20) between the pair of communication holes (5q, 5r) includes the intermediate communication hole (5s) at a position below the pair of communication holes (5q, 5r). [4] The venting structure according to any one of claims 1 to 3, wherein the plurality of compartments (20b, 20c) of the venting chamber (20) are an upper chamber (20b) and a lower chamber (20c) which are divided in the up-down direction by means of the dividing member (25e). [5] The vent structure according to claim 4, wherein the sealing member (25) is arranged inclined with respect to a horizontal direction, and an inclined lower end portion of the partition member (25e) includes partition communication holes (25m, 25n) through which oil flows from the upper chamber (20b) into the lower chamber (20c). [6] The vent structure according to claim 5, wherein a plurality of partitioning communication holes (25m, 25n) are provided, and the vent cover (21) includes a rib (21c) that performs a separation between the plurality of partitioning communication holes (25m, 25n). [7] The vent structure according to claim 6, wherein the partitioning communication holes (25m, 25n) are arranged at corner portions (21x, 21y) formed by a lid peripheral wall (21a) of the vent lid (21) and the rib (21c) or a projection part (21f) connected to the lid peripheral wall (21a) of the vent lid (21). [8] The venting structure according to claim 6 or 7, wherein the rib (21c) forms a labyrinth structure in the venting chamber (20). [9] The vent structure according to any one of claims 1 to 8, wherein an upper cover wall (21r) of the vent cover (21) is curved to follow an outer peripheral shape of a starter motor (15) arranged above the upper cover wall (21r).

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