CN116161150A - Power unit - Google Patents

Abstract

The present invention provides a power unit (4), which comprises: a crankshaft; a crankcase (40) that supports a crankshaft; and a fan (60) which is provided so as to be rotatable integrally with the crankshaft and which sucks in external air from the outside in the axial direction of the crankshaft. A cooling air passage (P1, P2) through which air generated by a fan (60) passes is formed in an outer portion of the fan (60) in the crankcase (40) when viewed from the axial direction.

Description

Power unit

Technical Field

The present invention relates to power units.

Background

In a conventional saddle-ride type vehicle, a structure is sometimes provided in which a power unit is forcibly cooled by a cooling fan. For example, japanese Kokai publication Sho-61-77463 discloses the following structure: a fan is mounted on the crankshaft, and a wind guide path facing the fan is provided on the outer side of the crankcase by a member provided separately from the crankcase. In addition, japanese patent application laid-open No. 2015-155653 discloses a structure in which a ribbed ridge is provided on a tank cover that covers an oil pan.

Disclosure of Invention

However, in the conventional cooling structure, there is room for improvement in the cooling efficiency of the housing itself of the power unit around the fan.

The invention provides a power unit capable of cooling the periphery of a fan with good efficiency.

The power unit according to the first aspect of the present invention includes: a rotation shaft; a housing supporting the rotation shaft; and a fan that is provided so as to be rotatable integrally with the rotary shaft and that sucks in external air from an outside in an axial direction of the rotary shaft, wherein an outside portion of the fan in the housing, viewed from the axial direction, forms a cooling air passage through which wind generated by the fan passes.

In the power unit according to the second aspect of the present invention, in addition to the power unit according to the first aspect, the power unit may include a cylinder member that is coupled to the housing and accommodates the piston so as to be reciprocable, and the cooling air passage may be provided separately from an air guide passage formed by the cylinder member.

In the power unit according to the third aspect of the present invention, in addition to the power unit according to the first or second aspect, the power unit may include a rib provided in the cooling air passage and extending in a radial direction of the rotary shaft.

In the power unit according to the fourth aspect of the present invention, in addition to the power unit according to the third aspect, the rib may be provided in the housing.

A power unit according to a fifth aspect of the present invention is the power unit according to any one of the first to fourth aspects, wherein the power unit includes a cover attached to the housing and covering the fan to divide the cooling air passage, and an exhaust port communicating with the cooling air passage is formed in the cover, and the cooling air passage is formed so that the air generated by the fan flows to the exhaust port without turning back to the upstream side.

A power unit according to a sixth aspect of the present invention may be the power unit according to any one of the first to fifth aspects, wherein the power unit includes a cover attached to the housing and covering the fan to divide the cooling air passage, and an exhaust port communicating with the cooling air passage is formed in the cover, and the exhaust port is opened in a direction inclined by 90 degrees or more with respect to a vertical upper direction and a vertical front direction.

In the power unit according to a seventh aspect of the present invention, in the power unit according to the fifth or sixth aspect, the air outlet may have a rear air outlet located rearward of the central axis of the rotary shaft, and the rear air outlet may be formed in a mesh shape and open to the outside in the vehicle width direction.

A power unit according to an eighth aspect of the present invention is the power unit according to any one of the fifth to seventh aspects, wherein the air outlet has a front air outlet located forward of a central axis of the rotary shaft, and the front air outlet is configured to exhaust air only downward of the housing.

A power unit according to a ninth aspect of the present invention is the power unit according to any one of the first to eighth aspects, wherein the cooling air passage may be provided in plurality so as to sandwich the lubricant oil discharge port.

A power unit according to a tenth aspect of the present invention is the power unit according to any one of the first to ninth aspects, wherein the housing has an oil pan for storing lubricating oil at a position below the rotation shaft, and the cooling air passage is provided outside the oil pan.

In the power unit according to an eleventh aspect of the present invention, in the power unit according to any one of the first to tenth aspects, the cooling air passage may be provided only below the rotation shaft.

According to the power unit of the first aspect, the portion of the housing located outside the fan when viewed in the axial direction exchanges heat with the wind generated by the fan passing through the cooling wind passage, so that the periphery of the fan can be cooled with good efficiency.

According to the power unit of the second aspect, since the air passing through the air guide passage formed by the cylinder member may be at a high temperature, the air that does not exchange heat with the cylinder member can be caused to flow into the cooling air passage. Thus, the periphery of the fan can be cooled efficiently.

According to the power unit of the third aspect, the wind generated by the fan flowing through the cooling wind path can be rectified. Thus, turbulence of the air flow in the cooling air passage can be suppressed, and heat exchange between the casing and the air generated by the fan can be promoted.

According to the power unit of the fourth aspect, the surface area of the casing in the cooling air passage is increased by the ribs, so that heat exchange between the casing and the wind generated by the fan can be promoted in the cooling air passage.

According to the power unit of the fifth aspect, the increase in the pressure loss of the air in the cooling air passage can be suppressed, and therefore the air generated by the fan can smoothly pass through the cooling air passage. Thus, heat exchange between the housing and the wind generated by the fan can be promoted.

According to the power unit of the sixth aspect, the exhaust port is opened in the direction inclined by 90 degrees or more with respect to the front, whereby it is possible to suppress entry of foreign matter flying from the front into the cooling air passage through the exhaust port during running of the vehicle. Further, by opening the air outlet in a direction inclined by 90 degrees or more with respect to the vertical upper direction, it is possible to suppress entry of foreign matter falling from above into the cooling air passage through the air outlet, and even if foreign matter enters into the cooling air passage through the air outlet, it is possible to discharge foreign matter through the air outlet by gravity. Thus, occurrence of a defect due to invasion of foreign matter into the cooling air passage can be suppressed.

According to the power unit of the seventh aspect, when the traveling wind flowing along the side surface on the outer side in the vehicle width direction in the power unit flows so as to sweep the rear air outlet, foreign matter easily intrudes into the cooling air passage through the rear air outlet, and therefore, by forming the rear air outlet in a mesh shape, intrusion of foreign matter into the cooling air passage can be effectively suppressed. In addition, when the rear end of the under cover is located in front of the power unit, water flowing along the side surface of the under cover is likely to scatter to a portion of the housing located in front of the central axis of the rotating shaft during traveling, and therefore, by configuring the rear air outlet to be opened only at a position rearward of the central axis of the rotating shaft, it is possible to suppress intrusion of water scattered from the under cover into the cooling air passage through the rear air outlet.

According to the power unit of the eighth aspect, the traveling wind flowing along the lower surface of the casing causes the front air outlet to generate negative pressure, so that the flow of air in the cooling air passage communicating with the front air outlet can be promoted. In addition, when the rear end of the under cover is located in front of the power unit, water flowing along the side surface of the under cover is likely to scatter toward a portion of the housing located in front of the central axis of the rotary shaft during traveling, and therefore, by configuring the front air outlet to exhaust only downward of the housing, it is possible to suppress intrusion of water scattered from the under cover into the cooling air passage through the front air outlet.

According to the power unit of the ninth aspect, the peripheral portion of the discharge port in the housing can be cooled effectively, and therefore the lubricating oil can be cooled at the time of oil discharge through the discharge port.

According to the power unit of the tenth aspect, the oil pan can directly exchange heat with the wind generated by the fan passing through the cooling wind passage. Thus, the lubricating oil can be cooled efficiently.

According to the power unit of the eleventh aspect, the portion of the casing where the heated lubricating oil is likely to contact can be intensively cooled. Thus, the portion of the casing that may be at a high temperature can be efficiently cooled.

Drawings

Fig. 1 is a left side view of a motorcycle according to an embodiment.

Fig. 2 is a right side view of the power unit of the embodiment.

Fig. 3 is a cross-sectional view taken along line III-III of fig. 2.

Fig. 4 is an enlarged view showing a state in which the fan cover and the shroud are removed from the power unit shown in fig. 2.

Fig. 5 is a cross-sectional view at line V-V of fig. 2.

Fig. 6 is a perspective view showing a part of the power unit shown in fig. 4.

Fig. 7 is a perspective view showing a part of the power unit shown in fig. 4.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same or similar structures are denoted by the same reference numerals. In addition, a repetitive description of these structures may be omitted. In the following description, the directions of the front-rear, upper-lower, left-right, and the like are the same as those of the vehicle described below. That is, the vertical direction coincides with the vertical direction, and the horizontal direction coincides with the vehicle width direction. In the drawings used in the following description, arrow UP indicates upward, arrow FR indicates forward, and arrow LH indicates leftward.

< vehicle overall Structure >)

Fig. 1 is a left side view of a motorcycle according to an embodiment.

As shown in fig. 1, a motorcycle 1 of the present embodiment is a saddle-ride type scooter type vehicle having a bottom pedal on which an occupant seated in a seat 7 sits. The motorcycle 1 includes a frame 2, front wheels 3 rotatably supported by the frame 2, a power unit 4 supported by the frame 2 so as to be capable of swinging up and down, rear wheels 5 supported by the power unit 4, and a body cover 6 forming an outer contour of the vehicle.

The frame 2 includes a head pipe 21, a down frame 22, a lower frame 23, a subframe 24, and a pair of rear frames 25, which are integrally joined by welding or the like. The head pipe 21 is provided at the front end of the frame 2. The head pipe 21 supports the front wheels 3 so as to be steerable via a steering rod passing through the head pipe 21. The down frame 22 branches from the head pipe 21 to the left and right and extends downward and rearward. The lower frame 23 extends rearward from the lower end of the lower frame 22 and then extends upward. The subframe 24 connects the lower frame 22 to the rear portion of the lower frame 23. The rear frame 25 is coupled to the sub-frame 24, and extends rearward and upward from a connection portion with the sub-frame 24. The rear end portion of the lower frame 23 is coupled to the middle portion of the rear frame 25.

The power unit 4 is a so-called unit swing type rear suspension. The power unit 4 drives a rear wheel 5 as a driving wheel. The power unit 4 is disposed from the front of the rear wheel 5 to the left side of the rear wheel 5. The power unit 4 is supported below the rear frame 25 on the vehicle frame 2 so as to be capable of swinging up and down. The structure of the power unit 4 will be described later.

The body cover 6 is constituted by a plurality of exterior panels. The body cover 6 includes a front cover portion 31 that covers the head pipe 21 and forms a leg shield, a front cover portion 32 that covers the lower frame 22, a central tunnel 33 that covers the sub-frame 24 rearward of the front cover portion 32, a lower cover portion 34 that covers the lower frame 23 below the central tunnel 33 and forms a floor step and a floor cover, and a rear cover portion 35 that covers the rear frame 25 rearward of the central tunnel 33. The plurality of exterior panels constituting the vehicle body cover 6 need not be divided according to the above-described cover portions, and may be disposed so as to straddle the boundary between the cover portions, or each cover portion may be constituted by a plurality of exterior panels.

< Power Unit >)

Fig. 2 is a right side view of the power unit of the embodiment. Fig. 3 is a cross-sectional view taken along line III-III of fig. 2.

As shown in fig. 2 and 3, the power unit 4 integrally includes an engine 11, an ACG starter motor 13, and a power transmission structure 12. The output of the engine 11 is transmitted from a crankshaft 14 (rotary shaft) to the rear wheels 5 via a power transmission structure 12. The power transmission structure 12 includes a transmission 15, a centrifugal clutch not shown, and a reduction mechanism.

The transmission 15 is a V-belt type continuously variable transmission coupled to the crankshaft 14. The transmission 15 is accommodated in a transmission case 16. The transmission case 16 is formed long in the vehicle width direction. The transmission case 16 is opened outward in the vehicle width direction. The transmission case 16 is closed by a transmission case cover 17, and a transmission chamber for accommodating the transmission 15 is formed inside the transmission case 16. A rear wheel axle 5a (an axle of the rear wheel 5) protruding toward the vehicle width center side is provided at the rear end portion of the power unit 4. The rotational power of the crankshaft 14 is transmitted to the rear wheel axle 5a via the power transmission structure 12, whereby the rear wheel 5 supported by the rear wheel axle 5a is driven to run the vehicle.

The ACG starter motor 13 functions as a starter and a generator. The ACG starter motor 13 is connected to a battery not shown. When the ACG starter motor 13 functions as a starter, the battery supplies electric power to the ACG starter motor 13. When the ACG starter motor 13 functions as a generator, the battery is charged with the regenerative power of the ACG starter motor 13. The engine 11 and the ACG starter motor 13 are controlled by a control unit not shown.

The engine 11 is a single cylinder engine in which a crankshaft 14 is oriented in the vehicle width direction.

The engine 11 includes a cylinder 41 (cylinder member), a piston, and a crankcase 40 (housing). The cylinder 41 is provided at the front of the power unit 4. The cylinder 41 includes a cylinder block 41a, a cylinder head 41b, and a cylinder head cover 41c. The cylinder head 41b is coupled to a front end portion of the cylinder block 41 a. The cylinder head cover 41c covers the front end portion of the cylinder head 41 b. A combustion chamber is formed in the cylinder 41.

The piston is coupled to the crankshaft 14 via a connecting rod 42. The piston is housed in the cylinder 41 so as to be reciprocable. The reciprocating movement of the piston is transmitted to the crankshaft 14 via the connecting rod 42. That is, the crankshaft 14 is rotated by the reciprocating movement of the piston. Hereinafter, the center axis C of the crankshaft 14 may be simply referred to as "axis C". The direction perpendicular to the axis C and extending radially from the axis C is referred to as a radial direction. In the present embodiment, the axis C extends in the vehicle width direction.

As shown in fig. 3, the crank case 40 rotatably supports the crankshaft 14. The crankcase 40 is disposed in front of the rear wheel 5 and is connected to the rear end portion of the cylinder block 41 a. The crankcase 40 is made of metal. The crankcase 40 is formed by fastening and connecting a left crankcase 40L and a right crankcase 40R divided in the left and right directions to each other. The right crankcase 40R forms a half of the crankcase 40. The left crankcase 40L forms a half of the crankcase 40.

The crankcase 40 includes a crank arm housing portion 45 that houses a crank arm 14a of the crankshaft 14, a motor housing portion 50 that houses the ACG starter motor 13, and an oil pan 55 that stores lubricating oil. A front portion of the transmission case 16 is disposed on the left side of the crank arm housing portion 45. The left crank case 40L is integrally formed with the transmission case 16.

The crank arm housing 45 is formed by the right crankcase 40R and the left crankcase 40L. The crank arm housing portion 45 forms a housing chamber a for housing the crank arm 14a and the crank pin of the crankshaft 14 between the right crankcase 40R and the left crankcase 40L. The crank arm housing portion 45 rotatably supports the crank journal 14c of the crankshaft 14 via a bearing 46R at a right side wall 45R provided in the right crankcase 40R. The crank arm housing portion 45 rotatably supports the crank journal 14c via a bearing 46L at a left side wall 45L provided in the left crankcase 40L. The crank arm housing portion 45 supports the crankshaft 14 such that an end portion of the crankshaft 14 protrudes outward in the vehicle width direction.

The motor housing portion 50 is provided at the right portion of the crankcase 40. The motor housing portion 50 is located on the right side of the crank arm housing portion 45 and is formed only by the right crankcase 40R. The motor housing portion 50 is opened to the outside in the vehicle width direction. The motor housing 50 cooperates with a fan cover 70 described later to form a motor housing chamber B housing the ACG starter motor 13.

Fig. 4 is an enlarged view showing a state in which the fan cover and the shroud are removed from the power unit shown in fig. 2.

As shown in fig. 3 and 4, the motor housing portion 50 includes a peripheral wall 51 surrounding the ACG starter motor 13 from the radially outer side. The peripheral wall 51 is provided with a cylinder side cutout 52. The cylinder side cutout 52 is formed on the cylinder 41 side with respect to the axis C when viewed in the vehicle width direction. The cylinder side cutout 52 is cut so that the inner side of the peripheral wall 51 is opened forward when viewed in the vehicle width direction.

As shown in fig. 3, an oil pan 55 is provided at a lower portion of the crankcase 40.

The oil pan 55 is located below the crank arm housing portion 45. The oil pan 55 is formed by the right crankcase 40R and the left crankcase 40L. The oil pan 55 is disposed from a lower position of the motor housing portion 50 to a lower position of the transmission case 16 through a lower position of the crank arm housing portion 45. The oil pan 55 forms a storage space for storing lubricating oil below the crankshaft 14. The lower surface of the oil pan 55 forms the lower surface of the crankcase 40. The oil pan 55 is provided with a lubricant drain port, not shown, which is opened at the bottom of the storage space. The discharge port is provided in the right crankcase 40R, and opens to the outside (right side) of the oil pan 55 in the vehicle width direction. The discharge port is closed by a drain bolt 56 (see fig. 2).

The ACG starter motor 13 is housed inside the motor housing portion 50. The ACG starter motor 13 is a motor in the form of an outer rotor. The ACG starter motor 13 is mounted to the crank journal 14c on the opposite side of the crank arm 14a from the bearing 46R. The ACG starter motor 13 includes a stator 13a and an outer rotor 13b.

The stator 13a is fixed to the right crankcase 40R. The stator 13a includes teeth and coils wound around the teeth. The outer rotor 13b is fixed to the right end portion of the crankshaft 14 (crank journal 14 c). The outer rotor 13b has a cylindrical shape covering the outer periphery of the stator 13 a. Magnets radially opposed to the stator 13a are provided on the inner peripheral surface of the outer rotor 13b. The ACG starter motor 13 generates power according to the relative rotation between the outer rotor 13b and the stator 13 a.

As shown in fig. 2 and 3, the power unit 4 further includes a cooling structure for cooling the engine 11 and the like. The cooling structure is mainly formed by the crankcase 40, the fan 60, the fan cover 70 covering the fan 60, and the shroud 65 covering the cylinder 41.

As shown in fig. 3 and 4, the fan 60 is disposed coaxially with the crankshaft 14 and is attached to the outer rotor 13b. The fan 60 is fixed to the right end portion of the crankshaft 14 via the outer rotor 13b, and is rotatable integrally with the crankshaft 14. The fan 60 is a centrifugal fan. The fan 60 includes a disk-shaped base portion 61 disposed coaxially with the axis C, blades 62 provided to stand from the base portion 61 to the outside in the vehicle width direction, and an upper plate 63 formed in an annular shape and coupled to each blade 62 on the opposite side of the base portion 61. The surface of the base 61 facing outward in the vehicle width direction extends inward in the vehicle width direction from the radially inner side toward the outer side. The blades 62 extend radially outward from the inner peripheral end on the rotation center side. The outer peripheral portions of the blades 62 protrude radially outward from the base 61. The upper plate 63 is disposed coaxially with the axis C. The upper plate 63 is coupled to the outer peripheral portion of the vane 62. The upper plate 63 extends inward in the vehicle width direction from the radially inner side toward the outer side. The fan 60 sucks air from the outside in the vehicle width direction through the blades 62 at the center of the fan 60 along with the rotation of the crankshaft 14, and generates wind radially outward through between the base 61 and the upper plate 63.

The upper plate 63 is provided with a fan side rib 63a. The fan side rib 63a is provided on a surface of the upper plate 63 facing outward in the vehicle width direction. The fan-side rib 63a extends circumferentially about the axis C when viewed in the vehicle width direction. The fan-side ribs 63a are disposed at intervals in the radial direction with respect to the inner peripheral edge and the outer peripheral edge of the upper plate 63.

As shown in fig. 3, the fan housing 70 is combined with the right crankcase 40R. The fan cover 70 has a shape that is open to the inside in the vehicle width direction as a whole. The fan cover 70 covers the fan 60 from the outside in the vehicle width direction, and a fan housing space D including a motor housing chamber B for housing the fan 60 and the ACG starter motor 13 is formed between the fan cover 70 and the motor housing portion 50. The fan cover 70 includes a cylindrical inlet nozzle 71 that opens toward the center of the fan 60, an outer tube 73 that surrounds the inlet nozzle 71 from the outside, and a connecting wall 74 that connects the outer tube 73 to the crankcase 40.

The inlet nozzle 71 guides the external air sucked by the fan 60 to the fan 60. The inlet nozzle 71 is disposed coaxially with the fan 60. The inner edge of the inlet nozzle 71 on the inner side in the vehicle width direction is located on the inner side in the radial direction from the fan side rib 63a of the fan 60, and faces the inner periphery of the upper plate 63 of the fan 60 in the vehicle width direction. The inner edge of the inlet nozzle 71 is located further outward in the vehicle width direction than the fan-side rib 63a. A shielding portion 72 that allows passage of air and restricts passage of foreign matter is fixedly provided inside the inlet nozzle 71. In the illustrated example, the shielding portion 72 is formed in a honeycomb shape. However, the structure of the shielding portion 72 is not particularly limited, and may be, for example, a mesh-like structure or a fixed or movable shutter.

The outer tube 73 is formed in a cylindrical shape and is disposed coaxially with the inlet nozzle 71. The outer tube 73 extends from an outer edge of the inlet nozzle 71 on the outer side in the vehicle width direction toward the inner side in the vehicle width direction, and is provided with a gap with respect to the inlet nozzle 71. The inner edge of the outer tube 73 on the inner side in the vehicle width direction is located on the outer side in the radial direction than the fan side rib 63a of the fan 60, and faces the upper plate 63 of the fan 60 in the vehicle width direction. The inner end edge of the outer tube 73 is located further inward in the vehicle width direction than the fan side rib 63a.

Fig. 5 is a cross-sectional view at line V-V of fig. 2.

As shown in fig. 3 and 5, the connecting wall 74 extends radially outward from the outer periphery of the outer tube 73 and inward in the vehicle width direction, and abuts against the opening edge of the peripheral wall 51 of the motor housing portion 50.

The connecting wall 74 extends around the outer tube 73 entirely when viewed in the vehicle width direction (see fig. 2).

As shown in fig. 2, the shroud 65 is combined with a fan cover 70. The shroud 65 is disposed in front of the fan cover 70. The shroud 65 is formed in such a manner as to be connected to the fan cover 70. The shroud 65 is provided so as to surround the cylinder block 41a and the cylinder head 41 b. The shroud 65 is disposed on the right side of the cylinder 41 so as to provide a gap with respect to the cylinder block 41a and the cylinder head 41 b. The space between the shroud 65 and the cylinder 41 communicates with the fan housing space D through the cylinder side cutout 52 of the peripheral wall 51 of the crankcase 40 (see fig. 4). The space between the shroud 65 and the cylinder 41 (the cylinder block 41a and the cylinder head 41 b) is a cylinder cooling air guide passage 66 through which the air generated by the fan 60 passes.

As shown in fig. 3 to 5, the portion of the crankcase 40 located outside the fan 60 when viewed from the axial direction cooperates with the fan cover 70 to form a first cooling air passage P1 and a second cooling air passage P2 through which the wind generated by the fan 60 passes. The first cooling air passage P1 and the second cooling air passage P2 are formed by portions (right side walls of the oil pan 55) extending radially outward from the right side walls 45r of the crank arm housing portion 45 when viewed from the axial direction. The first cooling air passage P1 and the second cooling air passage P2 are independent of the air guide passage 66. The first cooling air passage P1 and the second cooling air passage P2 communicate the fan housing space D with the outside of the power unit 4, respectively. The first cooling air passage P1 and the second cooling air passage P2 are provided so as to sandwich the drain bolt 56 and an oil drain hole (not shown) when viewed in the vehicle width direction.

As shown in fig. 3 and 4, the first cooling air passage P1 is provided below the air guide passage 66 when viewed in the vehicle width direction. The first cooling air passage P1 is provided forward and downward of the axis C when viewed in the vehicle width direction. The first cooling air passage P1 extends forward and downward from the fan housing space D when viewed in the vehicle width direction.

Fig. 6 and 7 are perspective views showing a part of the power unit shown in fig. 4.

As shown in fig. 3, 6 and 7, the first cooling air passage P1 communicates with the fan housing space D through a cutout 53 formed in the peripheral wall 51 of the motor housing portion 50. The first cooling air passage P1 extends along the outer surface of the oil pan 55. The first cooling air passage P1 is defined by the oil pan 55 and the pair of lateral walls 80 provided in the right crankcase 40R, and the extension 83 provided in the fan housing 70.

As shown in fig. 6 and 7, a pair of lateral walls 80 protrude outward in the vehicle width direction from the right side surface of the oil pan 55. A pair of lateral walls 80 extend downward and forward from both edges of the peripheral wall 51 of the motor housing portion 50 across the cutout 53. A pair of transverse walls 80 extend substantially parallel to each other. A rib 81 extending substantially parallel to the pair of transverse walls 80 is provided between the pair of transverse walls 80. The rib 81 protrudes outward in the vehicle width direction from the right side surface of the oil pan 55.

As shown in fig. 2 and 3, the extension 83 protrudes downward from the outer peripheral edge of the connecting wall 74 of the fan cover 70 when viewed in the vehicle width direction. The extension 83 includes an outer wall 84 extending from the connecting wall 74 at a distance from the oil pan 55, and a pair of side walls 85 extending from both side edges of the outer wall 84 toward the oil pan 55, and the extension 83 is formed in a U-shape in cross section that opens toward the crankcase 40. The outer wall 84 is disposed from a vehicle width direction outer side position with respect to the oil pan 55 to a lower side position with respect to the oil pan 55. The outer wall 84 includes an upstream portion 84a that overlaps with a space between the pair of cross walls 80 from the outside in the vehicle width direction and a downstream portion 84b that extends from the upstream portion 84a to the inside in the vehicle width direction. An upstream half of the first cooling air passage P1 is formed between the upstream portion 84a and the oil pan 55. The downstream portion 84b extends inward in the vehicle width direction from the lower end edge of the upstream portion 84a to a position below the oil pan 55. A downstream half of the first cooling air passage P1 is formed between the downstream portion 84b and the oil pan 55. The side wall 85 is connected to a portion of the outer wall 84 from the upstream portion 84a to the downstream portion 84b. The side wall 85 is provided so that an end edge of the oil pan 55 side abuts against an end edge of the lateral wall 80.

As shown in fig. 3, a front exhaust port 87 communicating with the first cooling air passage P1 is formed between the extension 83 and the oil pan 55. The front air outlet 87 is defined by an inner edge in the vehicle width direction of the downstream portion 84b of the outer wall 84, an inner edge in the vehicle width direction of each side wall 85, and a lower surface of the oil pan 55. The front exhaust port 87 is located forward of the axis C. The front air outlet 87 opens inward in the vehicle width direction. The front air outlet 87 discharges air only downward of the oil pan 55.

The first cooling air passage P1 formed as described above is formed such that, after the air generated by the fan 60 flows downward and forward from the cutout 53 of the peripheral wall 51 as the upstream end, the air changes direction to the inside in the vehicle width direction and flows to the front air outlet 87 as the downstream end. Thereby, the wind generated by the fan 60 flowing through the first cooling wind path P1 flows from the upstream end to the downstream end without turning back to the upstream side.

As shown in fig. 4 and 5, the second cooling air passage P2 is provided rearward of the first cooling air passage P1 when viewed in the vehicle width direction. The second cooling air passage P2 is provided at a position rearward and downward of the axis C when viewed in the vehicle width direction. The second cooling air passage P2 extends rearward and downward from the fan housing space D when viewed in the vehicle width direction.

As shown in fig. 5 to 7, the second cooling air passage P2 communicates with the fan housing space D through a cutout 54 formed in the peripheral wall 51 of the motor housing 50. The second cooling air passage P2 is defined by the oil pan 55 and the inner guide wall 90 provided in the right crankcase 40R, and the connecting wall 74 and the outer guide wall 92 provided in the fan cover 70.

The inner guide wall 90 extends so as to connect both edges of the cutout 54 in the peripheral wall 51 of the motor housing portion 50. The inner guide wall 90 extends so as to bulge radially outward from the peripheral wall 51 when viewed in the vehicle width direction (see fig. 4). The space inside the inner guide wall 90 is partitioned from the inside in the vehicle width direction by the right side wall of the oil pan 55. The space inside the inner guide wall 90 communicates with the fan housing space D to form an upstream half of the second cooling air passage P2, and is opened to the outside in the vehicle width direction. A rib 91 extending in the radial direction when viewed in the vehicle width direction is formed between the inner guide walls 90. In the illustrated example, the ribs 91 are provided with three. The rib 91 protrudes outward in the vehicle width direction from the right side surface of the oil pan 55. The radially outer end edge of each rib 91 is connected to the inner peripheral surface of the inner guide wall 90.

As shown in fig. 2 and 5, the outer guide wall 92 is provided radially outward of the connecting wall 74 of the fan cover 70. The outer guide wall 92 is formed so as to extend the inner guide wall 90 outward in the vehicle width direction. The outer guide wall 92 extends along the inner guide wall 90 when viewed in the vehicle width direction. Both ends of the outer guide wall 92 are connected to the connection wall 74 of the fan housing 70. Thus, the outer guide wall 92 and the connecting wall 74 form a closed cross section. A space that directly communicates with the space inside the inner guide wall 90 is formed between the outer guide wall 92 and the connecting wall 74 to form the downstream side half of the second cooling air passage P2. A rear exhaust port 94 communicating with the second cooling air passage P2 is formed between the outer guide wall 92 and the connecting wall 74. The rear exhaust port 94 is defined by an outer peripheral surface of the connecting wall 74 at an outer end edge of the outer guide wall 92 in the vehicle width direction. The rear exhaust port 94 is located rearward of the axis C. The rear exhaust port 94 opens outward in the vehicle width direction and overlaps the second cooling air passage P2 when viewed from the axial direction. The rear air outlet 94 is formed in a mesh shape, and allows air to pass therethrough and restricts the passage of foreign matter.

The second cooling air passage P2 formed as described above is formed such that, after the air generated by the fan 60 flows downward and rearward from the cutout 54 of the peripheral wall 51 as the upstream end, the air changes direction to the outside in the vehicle width direction and flows to the rear air outlet 94 as the downstream end. Thereby, the wind generated by the fan 60 flowing through the second cooling wind path P2 flows from the upstream end to the downstream end without turning back to the upstream side.

As described above, in the present embodiment, the first cooling air passage P1 and the second cooling air passage P2 through which the air generated by the fan 60 passes are formed in the outer portion of the fan 60 as viewed in the axial direction in the crankcase 40. According to this configuration, the portion of the crankcase 40 located outside the fan 60 when viewed in the axial direction exchanges heat with the wind generated by the fan 60 passing through the first cooling wind path P1 and the second cooling wind path P2, and therefore the peripheral edge of the fan 60 can be cooled with good efficiency.

The first cooling air passage P1 and the second cooling air passage P2 are provided separately from the air guide passage 66 formed in the cylinder 41. According to this configuration, since there is a possibility that the air passing through the air guide passage 66 formed in the cylinder 41 may be at a high temperature, the air that does not exchange heat with the cylinder 41 can be caused to flow into the first cooling air passage P1 and the second cooling air passage P2. Thus, the periphery of the fan 60 can be cooled efficiently.

The power unit 4 includes a rib 81 provided in the first cooling air passage P1 and extending in the radial direction, and a rib 91 provided in the second cooling air passage P2 and extending in the radial direction. According to this configuration, the wind generated by the fan 60 flowing through the first cooling wind path P1 and the second cooling wind path P2 can be rectified. Accordingly, turbulence of the air flows in the first cooling air passage P1 and the second cooling air passage P2 can be suppressed, and heat exchange between the crankcase 40 and the wind generated by the fan 60 can be promoted.

The ribs 81 and 91 are provided in the crankcase 40. According to this structure, the surface area of the crankcase 40 in the first cooling air passage P1 and the second cooling air passage P2 is increased by the ribs 81 and 91, so that heat exchange between the crankcase 40 and the fan 60 can be promoted in the first cooling air passage P1 and the second cooling air passage P2.

The first cooling air passage P1 and the second cooling air passage P2 are formed so that the air generated by the fan 60 does not flow back to the exhaust ports 87 and 94 on the upstream side. According to this configuration, since an increase in the pressure loss of the air in the cooling air passages P1 and P2 can be suppressed, the air generated by the fan 60 can smoothly pass through the cooling air passages P1 and P2. Thus, heat exchange between the crankcase 40 and the wind generated by the fan 60 can be promoted.

The front air outlet 87 and the rear air outlet 94 are opened in the vehicle width direction. According to this configuration, by opening the front air outlet 87 and the rear air outlet 94 in directions inclined by 90 degrees with respect to the front, it is possible to suppress entry of foreign matter flying from the front into the cooling air passages P1, P2 through the air outlets 87, 94 when the vehicle is traveling. Further, by opening the front air outlet 87 and the rear air outlet 94 in a direction inclined by 90 degrees with respect to the vertical upper direction, it is possible to suppress entry of foreign matter falling from above into the cooling air passages P1, P2 through the air outlets 87, 94, and to discharge foreign matter through the air outlets 87, 94 by gravity even if the foreign matter enters into the cooling air passages P1, P2 through the air outlets 87, 94. Thus, occurrence of a defect due to invasion of foreign matter into the cooling air passages P1, P2 can be suppressed.

The rear exhaust port 94 is formed in a mesh shape and opens to the outside in the vehicle width direction. According to this configuration, when the traveling wind flowing along the vehicle width direction outer side surface in the power unit 4 flows so as to sweep the rear air outlet 94, foreign matter is likely to enter the second cooling air passage P2 through the rear air outlet 94, and thus, by forming the rear air outlet 94 in a mesh shape, intrusion of foreign matter into the second cooling air passage P2 can be effectively suppressed. In addition, when the rear end of the under cover is located in front of the power unit 4, water flowing along the side surface of the under cover is likely to scatter to a portion of the crankcase 40 located in front of the axis C during running, and therefore, by configuring the rear air outlet 94 to be open only in a position rearward of the axis C, it is possible to suppress intrusion of water scattered from the under cover into the second cooling air passage P2 through the rear air outlet 94.

The front air outlet 87 is located forward of the axis C, and discharges air only downward of the crankcase 40. According to this structure, the front air outlet 87 can be caused to generate negative pressure by the running wind flowing along the lower surface of the crankcase 40, and the flow of air in the first cooling air passage P1 communicating with the front air outlet 87 can be promoted. In addition, when the rear end of the under cover is located in front of the power unit 4, water flowing along the side surface of the under cover is likely to scatter to a portion of the crankcase 40 located in front of the axis C during running, and therefore, by configuring the front air outlet 87 to exhaust only downward of the crankcase 40, intrusion of water scattered from the under cover into the first cooling air passage P1 through the front air outlet 87 can be suppressed.

The first cooling air passage P1 and the second cooling air passage P2 are provided so as to sandwich the discharge port of the lubricating oil. According to this structure, the peripheral portion of the drain port in the crankcase 40 can be cooled effectively, and therefore, the lubricating oil can be cooled at the time of oil discharge through the drain port.

The first cooling air passage P1 and the second cooling air passage P2 are provided outside the oil pan 55. According to this configuration, the oil pan 55 can directly exchange heat with the air generated by the fan 60 passing through the first cooling air passage P1 or the second cooling air passage P2. Thus, the lubricating oil can be cooled efficiently.

The first cooling air passage P1 and the second cooling air passage P2 are provided only below the crankshaft 14. With this structure, the heated portions of the crankcase 40 where the lubricating oil is likely to contact can be intensively cooled. Thus, the portion of the crankcase 40 that may be at a high temperature can be efficiently cooled.

The present invention is not limited to the above-described embodiment described with reference to the drawings, and various modifications are considered within the technical scope thereof.

For example, in the above-described embodiment, an example in which the present invention is applied to a power unit of a motorcycle is shown, but the application scope of the present invention is not limited to a power unit of a motorcycle. For example, the present invention can be applied to all power units for a saddle-ride type vehicle in which a driver rides across a vehicle body. Examples of the saddle-ride type vehicle include not only a motorcycle but also a motor tricycle, a bar racing car, ATV (All Terrain Vehicle), and other motor quadricycles. The power unit 4 of the above embodiment includes only the engine as the power source for running the vehicle, but the present invention is also applicable to a power unit including a motor as the power source.

In the above embodiment, the exhaust ports 87 and 94 are opened in the vehicle width direction, but the opening direction of the exhaust port is not particularly limited. However, it is preferable that the air outlet be opened in a direction inclined by 90 degrees or more with respect to the vertical upper direction and the front direction. By opening the air outlet in a direction inclined by 90 degrees or more with respect to the front, it is possible to suppress entry of foreign matter flying from the front into the cooling air passage through the air outlet when the vehicle is traveling. Further, by opening the air outlet in a direction inclined by 90 degrees or more with respect to the vertical upper direction, it is possible to suppress entry of foreign matter falling from above into the cooling air passage through the air outlet, and even if foreign matter enters into the cooling air passage through the air outlet, it is possible to discharge foreign matter through the air outlet by gravity.

In the above embodiment, the power unit is provided with a plurality of cooling air passages (the first cooling air passage P1 and the second cooling air passage P2), but only one cooling air passage may be provided.

In the above embodiment, the ribs 81 and 91 in the cooling air passages P1 and P2 are provided in the oil pan 55, but the ribs may be provided in the fan cover. In addition, the cooling air passage may not be provided with a rib.

The components in the above-described embodiments may be appropriately replaced with known components within a range not departing from the gist of the present invention.

Claims (11)

1. A power unit, wherein,

the power unit is provided with:

a rotation shaft;

a housing supporting the rotation shaft; and

a fan provided rotatably integrally with the rotary shaft and sucking outside air from an outside in an axial direction of the rotary shaft,

an outer portion of the fan in the housing, as viewed in the axial direction, forms a cooling air passage through which wind generated by the fan passes.

2. The power unit of claim 1, wherein,

the power unit includes a cylinder member coupled to the housing and housing a piston so as to be reciprocatingly movable,

the cooling air passage is provided separately from the air guide passage formed by the cylinder member.

3. The power unit according to claim 1 or 2, wherein,

the power unit includes a rib provided in the cooling air passage and extending in a radial direction of the rotary shaft.

4. The power unit of claim 3, wherein,

the rib is provided to the housing.

5. The power unit according to any one of claims 1-4, wherein,

the power unit includes a cover attached to the housing and covering the fan to divide the cooling air passage,

an air outlet communicating with the cooling air passage is formed in the cover,

the cooling air passage is formed so that the air generated by the fan does not flow back to the exhaust port.

6. The power unit according to any one of claims 1-5, wherein,

the power unit includes a cover attached to the housing and covering the fan to divide the cooling air passage,

an air outlet communicating with the cooling air passage is formed in the cover,

the exhaust port opens in a direction inclined by 90 degrees or more with respect to the vertical upper direction and the vertical front direction.

7. The power unit according to claim 5 or 6, wherein,

the air outlet has a rear air outlet located at a position rearward of the central axis of the rotary shaft,

the rear exhaust port is formed in a mesh shape and opens to the outside in the vehicle width direction.

8. The power unit according to any one of claims 5-7, wherein,

the air outlet has a front air outlet located in front of the central axis of the rotary shaft,

the front air outlet only discharges air to the lower part of the shell.

9. The power unit according to any one of claims 1-8, wherein,

the cooling air passage is provided in plurality so as to sandwich the lubricant oil discharge port.

10. The power unit according to any one of claims 1-9, wherein,

the housing has an oil pan for storing lubricating oil at a position below the rotating shaft,

the cooling air passage is provided outside the oil pan.

11. The power unit according to any one of claims 1-10, wherein,

the cooling air passage is provided only below the rotation shaft.

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