JP2003019993A - Motorcycle engine cooling structure - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To increase the amount of traveling wind guided to an engine near the rear of a front fender. A fork cover that covers a front fork from the outside of a vehicle body is provided integrally with a front fender. The outer surface 31a of the fork cover 31 at a portion corresponding to the front fork 11 is a convex curved surface protruding outward from the vehicle body in plan view. The outer surface 31a of the fork cover 31 is covered with the boundary layer
3 is formed by a streamline-shaped boundary layer forming portion 34 in which a boundary layer 33 is extended from the rear end of the boundary layer forming portion 34 to separate the boundary layer 33 from the outer surface 31a. The peeling portion A was formed such that the peeling point A of the peeling portion 35 was located on the rear side of the vehicle body from the protruding end of the convex curved surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine cooling structure for a motorcycle that guides traveling wind to an engine located near the rear of a front fender.

[0002]

2. Description of the Related Art Conventionally, as a motorcycle, there is one in which an engine is mounted in the vicinity of the rear of a front fender and a cylinder of the engine is directed to the front of the vehicle body. In this type of motorcycle, the running wind is blocked by the front wheels and the front fenders, making it difficult for the engine to hit the engine. There is.

[0003]

[Problems to be Solved by the Invention] However, the traveling wind hitting the front fork and the front fender is
Since the flow direction is changed to the outside and it is difficult to enter the inside of the leg shield, the conventional cooling structure described above has a limit in increasing the amount of traveling wind guided to the engine. For this reason, there has been a problem that engine cooling becomes insufficient when the engine output is increased.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to increase the amount of traveling wind introduced to the engine near the rear of the front fender.

[0005]

In order to achieve this object, a cooling structure for an engine of a motorcycle according to the present invention comprises:
A fork cover that covers the front fork from the outside of the vehicle body is provided integrally with the front fender, and an outer surface of a portion of the fork cover corresponding to the front fork is a convex curved surface that projects toward the outside of the vehicle body in a plan view,
The outer surface of the fork cover is extended to the streamline-shaped boundary layer forming portion where a boundary layer formed of traveling wind is formed and the rear end of the boundary layer forming portion so that the boundary layer is separated from the outer surface. And the peeling point of the peeling portion is formed so that the peeling point of the peeling portion is located on the rear side of the vehicle body with respect to the protruding end of the outer surface. According to the present invention, the traveling wind that flows along the outer surface of the fork cover is changed to the inside of the vehicle body by passing near the fork cover.

A motorcycle engine cooling structure according to a second aspect of the present invention is the motorcycle engine cooling structure according to the first aspect, in which the fork cover flows outside the fork cover. It is provided with an air guide duct that changes the flow direction of running wind to the inside of the vehicle body. According to the present invention, traveling wind outside the boundary layer along the fork cover can be guided to the inside of the vehicle body by the wind guide duct.

The engine cooling structure for a motorcycle according to a third aspect of the present invention is the engine cooling structure for a motorcycle according to the first or second aspect of the invention, wherein the rear part of the front fender is rearward. With a leg shield to cover, above the running wind inlet facing the upper end of the front fender in this leg shield,
An air guide member that guides traveling wind to the traveling air inlet is provided by an air guide surface that is inclined rearward and downward. According to the present invention, traveling wind that flows behind the vehicle body between the leg shield and the front fender can be guided to the engine side along the upper surface of the front fender.

A motorcycle engine cooling structure according to a fourth aspect of the present invention is the motorcycle engine cooling structure according to the first or second aspect of the present invention, wherein the engine cylinder is viewed from the side. A leg shield for covering is provided, and an air guide member for guiding traveling wind to the ignition plug side is provided on an inner surface of the leg shield adjacent to the ignition plug. According to the present invention, traveling wind can be applied to the spark plug attachment portion, which is the high temperature portion of the cylinder.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an engine cooling structure for a motorcycle according to the present invention will be described in detail below with reference to FIGS. FIG. 1 is a side view showing a front half of a motorcycle which employs a cooling structure according to the present invention, and FIG.
Front Fender and Leg Shield II-II in Japan
FIG. 3 is a sectional view showing a main part in an enlarged manner, and FIG. 4 is a sectional view taken along line IV-IV of the leg shield and the air guide member in FIG.

In these figures, the reference numeral 1 indicates a motorcycle according to this embodiment. This motorcycle 1 has an air-cooled 4-cycle single-cylinder engine 2 mounted near the rear of a front wheel 3. The engine 2 is formed so that the axis of the cylinder 4 is directed toward the front of the vehicle body, and is mounted on the vehicle body frame 6 so that the cylinder 4 is located near the rear of the front fender 5.

As is well known, the body frame 6 has a main pipe 8 extending rearward and downward from a head pipe 7 and a rear arm bracket (not shown) and a rear arm bracket (not shown) at the rear end of the main pipe 8. The seat rail is connected. The head pipe 7 rotatably supports a telescopic front fork 11, and the front fork 11 supports the steering handle 12, the front wheel 3, and the front fender 5.

The head pipe 7 and the main pipe 8 are
It is covered with a front cover and a leg shield 14 indicated by reference numeral 13 in the drawing. The front cover 13 covers the head pipe 7 from the front of the vehicle body, and is supported on the vehicle body frame 6 by a bracket 15 shown by reference numeral 15 in FIG. This bracket 15
Is formed in a U shape that is open toward the rear of the vehicle body in a plan view, and the rear end portion is fixed to both side portions of the vehicle body frame 6 with the vehicle body frame 6 inserted in the central portion,
A front cover 13 is attached to the front end.

The bracket 15 has a first baffle plate 16 welded to the lower surface of the front end thereof. This first baffle plate 16
Is a central portion in the vehicle width direction in front of the head pipe 7, and includes a lower edge of the front cover 13 and the front fender 5.
It is arranged at a position where the running wind that flows into the front cover 13 through the gap between the bracket and the front cover 13 hits, and is horizontally stretched between the pair of left and right extending portions 15a of the bracket 15 in the front-rear direction. Since the front-rear extending portion 15a is inclined rearward and downward, the first air guide plate 16 is also inclined rearward and downward. The first baffle plate 16 constitutes the baffle member according to the invention described in claim 3, and the front surface (the surface that faces the front lower side) of the first baffle plate 16 is the baffle surface according to the invention. Are configured.

The leg shield 14 includes a base portion 17 (see FIG. 2) having a structure that covers the head pipe 7 and the main pipe 8 from the upper rear side, and lower ends (front ends) on both left and right sides of the base portion 17, respectively. It is configured by the left and right shield portions 18 extending laterally, and an air guide path 19 for guiding traveling wind to the engine 2 is formed by the inner surface. In addition, the carburetor 2 of the engine 2 is provided in the air guide passage 19.
It accommodates a and an air cleaner 2b. The base 17
Has a U-shaped cross-section that opens downward (forward), and accommodates the engine 2 inside the open portion.

As shown in FIG. 2, the shield portion 18 includes an inner portion 18a that gradually extends laterally toward the front side of the vehicle body, and an outer portion that extends rearward of the vehicle body from the tip of the inner portion 18a. And 18b, it is formed in a V-shaped cross section that is opened toward the rear of the vehicle body. In this embodiment, the shield part 18 includes the front fender 5
The leg shield 14 extends rearward and downward from the front end so as to cover the rear portion from the rear. As shown in FIG. 1, the lower end portion of the shield portion 18 is formed so as to overlap the cylinder 4 of the engine 2 in a side view.

As shown in FIG. 4, a second baffle plate 22 is formed on the inner surface of the left and right shield parts 18 at the lower end of the shield part 18 on the right side of the vehicle body and adjacent to the spark plug 21 of the engine 2. Is installed. This second baffle plate 22 is
An air guide portion 22a made of a steel plate and curved so as to gradually extend toward the inside of the vehicle body toward the rear, and a cut-and-raised portion 22b linearly extending from the middle of the air guide portion 22a to the rear are integrally formed. Is forming. The cut-and-raised portion 22b is fixed to the shield portion 18 with a fixing bolt 23. The air guide portion 22a is formed in such a shape that the traveling wind flowing into the inside of the lower end of the leg shield is directed to the inside of the vehicle body and the traveling wind is blown to the ignition plug mounting portion of the cylinder 4. Second baffle plate 22
The running wind that flows along is shown by an arrow in FIG. The second
The baffle plate 22 of No. 4 constitutes the baffle member according to the invention described in claim 4.

At the front end of the leg shield 14, a traveling wind duct 24 extending rearward and downward on both sides of the head pipe 7.
Is provided. The duct 24 has an upstream end (the traveling wind introduction port 2) at a portion facing the upper end of the front fender 5.
5) is formed, the left and right shield portions 18 are formed as outer walls, and the rear ends are opened in the leg shield 14.
The first baffle plate 16 is arranged above the traveling air introduction port 25. For this reason, the traveling wind whose flow direction hits the first baffle plate 16 is changed to the rear lower direction flows into the traveling wind duct 24 from the vicinity of the traveling wind inlet 25. In the air guide path 19 in the leg shield 14 including the traveling wind duct 24, traveling wind passing between the front cover 13 and the front fender 5 and both sides of the front fender 5 and the front wheel 3 (front fork 11) are provided. And the running wind passing through.

In this motorcycle 1, the front fender 5 is provided with a fork cover 31 in order to increase the flow rate of the traveling wind flowing into the air guide passage 19 through the side of the front fender 5. The fork cover 31 is integrally formed with the air guide duct 32 to guide the traveling wind to the engine 2 side.

As shown in FIGS. 1 and 2, the fork cover 31 is attached to the front fender 5 so as to cover the front fork 11 from the outside of the vehicle body. In this embodiment, the front fender 5a and the rear fender 5b of the front fender 5 are fixed to each other by a locking structure (not shown). Further, the fork cover 31 is formed of a synthetic resin into a predetermined shape, and as shown in FIGS. 2 and 3, the outer surface 31a of the portion corresponding to the front fork 11 is a protrusion protruding toward the outside of the vehicle body in a plan view. It is formed to have a curved surface.

The outer surface 31a is, as shown in FIG.
A streamline-shaped boundary layer forming portion 34 in which a boundary layer 33 made of traveling wind is formed, and a peeling portion extending at the rear end of the boundary layer forming portion 34 and separating the boundary layer 33 from the outer surface 31a. And 35. The peeling section 35 is
The peeling point A is formed so as to be located on the rear side of the vehicle body with respect to the protruding end of the outer surface 31a. That is, the traveling wind that has flowed in layers along the boundary layer forming portion 34 is changed inward in the vehicle body from the maximum diameter portion of the front fork 11, and is separated from the fork cover 31 at the separation point A to separate from the engine. It is led to the 2nd side. In this embodiment, the peeling section 3
Although 5 is formed by a convex curved surface and a concave curved surface, it may be formed by extending a flat surface so as to extend rearward at the rear end of the convex curved surface.

As shown in FIGS. 2 and 3, the air guide duct 32 has a plate-like shape that laterally covers the rear portion of the fork cover 31, and is curved along the outer surface 31a of the fork cover 31. The fork cover 31 is formed laterally away from the fork cover 31 so that the traveling air passage 36 is formed between the fork cover 31 and the outer surface 31a. In this way, the wind duct 3
By providing 2 on the fork cover 31, it is possible to change the flow direction of the traveling wind flowing outside the fork cover 31 and flowing into the air duct 32 to the inside of the vehicle body. This running wind is shown by a two-dot chain line W in FIG.

According to the cooling structure having the fork cover 31 described above, the outer surface 3 of the fork cover 31 during traveling.
The traveling wind flowing along 1a (the traveling wind forming the boundary layer 33) is changed to the inside of the vehicle body by passing through the vicinity of the fork cover 31, and as shown by an arrow in FIG. It flows into the air guide passage 19 in 14 and is guided to the engine 2. Along with this, the traveling wind W outside the traveling wind (the traveling wind forming the boundary layer 33) flowing along the fork cover 31 is changed inward by the wind guide duct 32 to the inside of the vehicle body. It flows into the air duct 19.

Therefore, by providing this cooling structure, the amount of traveling wind hitting the engine 2 can be increased, so that the engine 2 can be sufficiently cooled even if the output of the engine 2 is increased. In addition, of the traveling wind flowing rearward through the space between the front fender 5 and the front cover 13, the front cover 1
The traveling wind that has flowed into the inside 3 is changed to the rearward and downward direction by the first baffle plate 16 provided on the front cover supporting bracket 15, and flows into the baffle passage 19 inside the leg shield 14. For this reason, the traveling wind passing not only on both sides of the front fender 5 but also above can be reliably guided to the engine 2, so that the engine 2 can be cooled more efficiently. Further, the second baffle plate 22 provided near the ignition plug 21 in the leg shield 14
Since the traveling wind can be applied to the ignition plug mounting portion of the cylinder 4 by the above, the high temperature portion of the cylinder 4 can be intensively cooled by the traveling wind.

[0024]

As described above, according to the present invention, the traveling wind flowing along the outer surface of the fork cover is changed to the inside of the vehicle body by passing near the fork cover. Therefore, the traveling wind flowing near the sides of the front fender can be guided to the engine side, so that the engine can be efficiently cooled by the traveling wind. As a result, the engine can be sufficiently cooled even if the output of the engine is increased.

According to the second aspect of the present invention, since the traveling wind outside the boundary layer along the fork cover can be guided to the inside of the vehicle body by the wind guide duct, the amount of traveling wind introduced to the engine can be increased. Therefore, the engine can be cooled more efficiently.

According to the third aspect of the present invention, the traveling wind flowing rearward of the vehicle body between the leg shield and the front fender can be guided to the engine side along the upper surface of the front fender. It is possible to further increase the amount of traveling wind that hits. According to the invention described in claim 4, since the traveling wind can be applied to the ignition plug mounting portion which is the high temperature portion of the cylinder, the engine can be efficiently cooled with a small amount of traveling wind.

[Brief description of drawings]

FIG. 1 is a side view showing a front half of a motorcycle that employs a cooling structure according to the present invention.

FIG. 2 is a sectional view taken along line II-II of the front fender and the leg shield in FIG.

FIG. 3 is a cross-sectional view showing an enlarged main part.

4 is a sectional view taken along line IV-IV of the leg shield and the second baffle plate in FIG.

[Explanation of symbols]

2 ... Engine, 4 ... Cylinder, 5 ... Front fender, 11 ... Front fork, 14 ... Leg shield,
16 ... First baffle plate, 21 ... Spark plug, 22 ... Second baffle plate, 25 ... Traveling air introduction port, 31 ... Fork cover,
31a ... Outer surface, 32 ... Air duct, 34 ... Boundary layer forming part, 35 ... Peeling part, A ... Peeling point.

Claims (4)

[Claims] 1. A cooling structure for an engine of a motorcycle, which guides traveling wind to an engine located near the rear of a front fender, wherein a fork cover for covering the front fork from the outside of the vehicle body is provided integrally with the front fender. The outer surface of the portion of the cover corresponding to the front fork is a convex curved surface that projects toward the outside of the vehicle body in a plan view, and the outer surface of the fork cover is a streamline-shaped boundary layer in which a boundary layer of running wind is formed. The boundary part is formed by a forming part and a peeling part extending at the rear end of the boundary layer forming part to separate the boundary layer from the outer surface. A cooling structure for a motorcycle engine that is formed so as to be located on the side. 2. The engine cooling structure for a motorcycle according to claim 1, wherein the fork cover is provided with an air guide duct for changing a flow direction of traveling wind flowing outside the fork cover to an inside of the vehicle body. Cooling structure for motorcycle engines. 3. The engine cooling structure for a motorcycle according to claim 1, further comprising a leg shield that covers a rear portion of a front fender from a rear side, and a running wind that faces an upper end portion of the front fender in the leg shield. A cooling structure for an engine of a motorcycle, wherein an air guide member for guiding traveling wind to the traveling air introduction port is provided above the introduction port by a wind guide surface that is inclined rearward and downward. 4. The engine cooling structure for a motorcycle according to claim 1, further comprising a leg shield that laterally covers the cylinder of the engine, and a traveling wind is provided on an inner surface of the leg shield adjacent to the ignition plug. Cooling structure for motorcycle engines equipped with an air guide member that guides the engine to the spark plug side.