JP2852949B2 - Motorcycle air-cooled engine - Google Patents

Description

The present invention relates to an air-cooled engine mounted on a motorcycle,
More specifically, the present invention relates to an air-cooled engine for a motorcycle that can improve cooling performance and output with a compact configuration.

(Prior art)

In an air-cooled engine mounted on a motorcycle, if the cylinder body is tilted horizontally or forward to lower the vehicle body posture, the traveling wind often hits the cylinder head but hardly hits the cylinder body. Therefore, it is difficult to efficiently cool the entire engine, and as a result, it is difficult to improve the output. In order to improve the output of such an engine, there is one in which a cylinder body is surrounded by a shroud and forced air is blown along the shroud by a cooling fan (Japanese Patent Laid-Open No. 64-64).
No. 8533).

However, in the structure proposed in the past, there is a limit in further improving the cooling performance, and in order to increase the output, it is necessary to cover the entire engine with a shroud, thereby increasing the size of the cooling fan and the shroud. There was a drawback that it became impossible to obtain.

[Problems to be solved by the invention]

An object of the present invention is to solve the above-mentioned conventional disadvantages and to improve the cooling performance while enabling a compact structure,
It is an object of the present invention to provide an air-cooled engine of a motorcycle that enables higher output to be improved.

[Means for solving the problem]

The present invention to achieve the above object is to provide a motorcycle equipped with a cooling engine so that a cylinder body having cooling fins disposed on the outer periphery is horizontally or forward tilted. While forming a heat-dissipating base fin extending in a direction perpendicular to the cylinder axis, a cooling fan that rotates by engine power is provided on the engine side, and cooling air of the cooling fan is supplied outside the cylinder body to the cylinder body. A shroud for guiding the cooling fins and the back surface of the base fin is mounted, and a left shroud portion provided with a through hole for intake at a position facing the cooling fan and a right shroud portion provided with an exhaust port are provided. The right shroud part is elastically supported by the engine body, and the left shroud part is Through the digit connecting portion connected to the right shroud portion, characterized in that as the shroud portion thereof left and right surround only the back surface of the cooling fins and the base fins of the cylinder body.

〔Example〕

1 to 4 show an example of the air-cooled engine according to the present invention, and FIG. 5 shows a motorcycle equipped with the air-cooled engine.

In the motorcycle shown in FIG. 5, 1 is a body frame, 2 is a front wheel, 3 is a rear wheel, 4 is an engine, and 5 is a cowl provided on the entire body as a wind shield. An air cleaner 6 and a carburetor 7 are connected to the intake side of the engine 4, and an exhaust pipe 8 is connected to the exhaust side. Engine 4
The rear wheel 3 is driven via a chain 10 from a sprocket 9 provided at the rear.

In the air-cooled engine 4 shown in FIGS. 1 to 4, 11 is a cylinder body, 12 is a cylinder head, and 13 is a crankcase, which constitutes an engine body. The cylinder body 11 and the cylinder head 12 are connected by bolts (not shown) at four places on the outer periphery thereof.
And the crankcase 13 are similarly connected by bolts (not shown) at four locations on the outer periphery. Needless to say, this connection may be achieved by fixing the cylinder head 12 and the cylinder body 11 to the crankcase 13 by one through bolt, instead of using the above-described separation bolt.

A large number of cooling fins 11f are provided on the outer circumference of the cylinder body 11.
Are provided in multiple stages. Of these, the cooling fin 11f provided closest to the crankcase 13 has a larger shape than the other fins. On the other hand, a large number of cooling fins 12f are also provided on the surface of the cylinder head 12 so as to stand upright, and a cooling base fin 12b is provided on the outer periphery of the cylinder body so as to extend in a direction perpendicular to the cylinder axis direction. Have been. On the back surface of the base fin 12b, uneven cooling fins 12m having a small height are also arranged in multiple rows.

14 is a piston and 15 is a crankshaft. Crankshaft 15
The centrifugal clutch 16 (only the outer shape is indicated by a dashed line) is connected to one end (right end) thereof, and a multi-plate clutch 17 is operatively connected to the centrifugal clutch 16. Power is further transmitted from the multi-plate clutch 17 to the sprocket 9.

A generator 18 is connected to the other end (left end) of the crankshaft 15, and a cooling fan 19 is fixed to a top surface of a rotor 20 of the generator 18. The generator 18 has an outer periphery of the rotor 20 surrounded by a cover 21 made of aluminum casting via a gap 22. The partition-like cover 21 partially extends to the sprocket 9 and covers the outside of the sprocket 9.

A plurality of blades 23 of the cooling fan 19 extend radially at predetermined intervals on the outer periphery of the conical base, and the rotor 23
It is provided so as to be substantially perpendicular to the top surface of 20. Further, the outer ends of the plurality of blades 23 are integrally connected to each other by an annular plate 23p. Also, those wings 23
Part of the gap extends from the top surface of the rotor 20 to the outer peripheral surface.
It is shaped to extend into 22. Due to the blade 23 having such a shape, a part of the cooling air is
Side is forcibly supplied. The cooling air enters the rotor 20 and cools the generator 18, and then circulates so as to be exhausted again through the through hole 24 on the top surface.

Also, on the outside of the cooling fan 18 and the cylinder body 11,
A resin shroud 25 is provided. Shroud 25
Sends the cooling air generated by the cooling fan 19 to the cylinder body 11
Further, a guide path leading to the back surface of the base fin 12b of the cylinder head 12 is formed. The shroud 25 includes a left shroud portion 25a and a right shroud portion 25b which are divided into two. The left shroud portion 25a is provided with a through hole 28 for intake at a position facing the cooling fan 19, and the right shroud portion 25b is provided with an exhaust port 29.

Right shroud part 2 of both left and right shroud parts 25a, 25b
5b is through a rubber grommet 32 with a bolt 30,
It is fixed to the crankcase 13 at a plurality of positions together with the crankcase cover 31, and is elastically supported by the engine body. The left shroud portion 25a is connected to the right shroud portion 25b fixed as described above via connecting portions 26 and 27 provided on the mating surface of the two, and
The shroud 25 is configured to be fixed to the generator cover 21 at a location indicated by Z in the drawing. With the shroud 25 composed of the left and right shroud portions 25a and 25b, only the back surfaces of the cooling fins 11f of the cylinder body 11 and the base fins 12b of the cylinder head 12 are surrounded, and the cylinder head 1
The cooling fins 12f provided on the surface of 2 are not enclosed.

The left and right shroud portions 25a, 25b have rubber seals 33, 34 attached to their peripheral edges, respectively.
The cylinder head 12 and the generator cover 21 are brought into contact with each other via 3, 34. Among these, the portion of the sealing material 33 that comes into contact with the base fin 12b in an annular shape is divided into two parts,
Each is independently mounted on the left shroud portion 25a and the right shroud portion 25b. Also, of the cooling fins of the cylinder body 11, the cooling fin provided closest to the crankcase
A sealing material 37 is attached to the inner surface of the shroud 25 so as to surround the cooling fin 11f so as to abut the outer periphery of the cooling fin 11f. Another sealing member 38 attached to the end of the generator cover 21 is in contact with the outer peripheral portion of the cooling fin 11f other than the contact of the sealing member 37. By providing these seal members 33, 34, 37, and 38, the cooling air is prevented from leaking from the middle of the cooling air passage, and efficient cooling is performed.

When the motorcycle equipped with the air-cooled engine having such a configuration travels, the front cylinder head 12 is cooled by the traveling wind. Cooling at this time is performed very efficiently because the cylinder head 12 has the base fins 12b and the cooling surface of the base fins 12b faces the traveling wind. Meanwhile, cooling fan 19
After the outside air is sucked through the through hole 28 of the shroud 25, forced air is blown to the cylinder body 11 side. Here, the cooling air exchanges heat with the cooling fins 11f, and also contacts the back surface of the base fins 12b of the cylinder head 12 to perform heat exchange. The heat exchange with the base fins 12b can be further improved by providing the fins 12m as shown. Projection wall provided on the cooling air blowing side
35 is for preventing the cooling air blown out by the cooling fan 19 from returning to the cooling fan side again, and the wall formed integrally with the cover 21 and the left shroud portion 25a having the same shape as this.
It is formed by abutting a molded wall on the side.

In the cooling mechanism according to the present invention, the cylinder head 12 is efficiently cooled by providing the base fins 12b on the cylinder head 12 as described above. Therefore, the amount of heat conducted from the cylinder head 12 to the cylinder body 11 side is reduced, and the cooling fan 19 can reduce the cooling capacity for the cylinder body 11 by the reduced amount.
As a result, the size of the cooling fan 19 can be reduced, and accordingly, the shroud 25 can be reduced in size. As a result, the cooling mechanism can be made compact as a whole. Also. Left shroud part where the shroud 25 is divided into two as described above
25a and a right shroud portion 25b.
While attaching the left shroud 25b to the engine body side, the shroud 2 having an intake / exhaust port for connecting the left shroud portion 25a to the right shroud portion 25b through connecting portions 26 and 27 formed on the mating surface.
It becomes easy to mount the device 5 so as to surround only the back surfaces of the cooling fins 11f of the cylinder body 11 and the base fins 12b of the cylinder head 12.

FIG. 6, FIG. 7, and FIG. 8 each show another embodiment.

In the embodiment shown in FIG. 6, the shroud 25 (right shroud portion 25) is used.
The fixing of b) is performed on the lowermost cooling fin 11f. This fixing is performed at four positions by means of screws 36 via rubber chromets 32. In the case of this engine, the cylinder head 12, the cylinder body 11,
The fixing of the crankcase 13 is performed by through bolts.

In the embodiment shown in FIG. 7, the shroud 25 (right shroud portion 25) is used.
The fixing of b) is performed on the base fin 12b of the cylinder head 12. This fixing is also performed at the four positions by the screws 36 via the rubber grommets 32 in the same manner as described above.

Further, in the embodiment of FIG. 7, the cover 41 covering the outer periphery of the generator 18 is constituted by an integral cylindrical wall extending from the crankcase 13, and is different from the cover 21 as a separate member as in the above-described embodiment. is not. Further, a flat plate 42 is provided between the outer end surface of the cover 41 and the shroud 25.

In the embodiment of FIG. 8, a ring gear 43 for a starter motor is provided via a one-way clutch 44 on the shaft end of the crankshaft 15 on the side where the generator 18 is fixed. Further, the rotor 20 of the generator 18 does not open toward the inside as in the above-described embodiment, but opens toward the outside, and the cover 21 covers the outside. 45 is a pulsar coil, 46 is its cover, and is integrally formed with the generator cover 21.

In this embodiment, the cooling air for the generator is a cylinder body.
11 is introduced from the air introduction port 47 communicating with the outer peripheral side of the
After cooling the rotor 20 and the like, the air is drawn out from the gap between the generator cover 21 and the crankshaft 15 to the back side of the cooling fan 19.

In all of the above-described embodiments, the cylinder head 12 can be attached and detached while the shroud 25 is attached, thereby improving the maintainability.

〔The invention's effect〕

As described above, the air-cooled engine for a motorcycle in which the cylinder body according to the present invention is inclined horizontally or forward is provided with cooling fins standing on the surface of the cylinder head and radiating heat extending in the direction perpendicular to the cylinder axis on the outer periphery. A cooling fan that rotates by engine power is provided on the engine side, and the cooling air of the cooling fan is provided outside the cylinder body only on the cooling fin of the cylinder body and on the back surface of the base fin. Since the shroud for guiding is installed, the cylinder head can be efficiently cooled by traveling wind through the cooling fins standing on its surface and the base fins on the outer periphery.On the other hand, only the cylinder body side can be cooled by the cooling fan. Improving the cooling performance of the entire engine while enabling compactness with the configuration, Ri becomes possible to obtain a high output.

Also, the shroud has a two-part structure consisting of a left shroud part provided with a through hole for intake at the position facing the cooling fan and a right shroud part provided with an exhaust port, and the right shroud part is attached to the engine body, Since the shroud portion is connected to the right shroud portion via a connecting portion provided at the joint surface of the two shroud portions, the shroud having the air intake / exhaust port surrounds only the back surfaces of the cooling fins of the cylinder body and the base fins of the cylinder head. And can be easily attached.

[Brief description of the drawings]

1 is a cross-sectional view of an air-cooled engine according to an embodiment of the present invention, FIG. 2 is a side view of the engine, and FIG. 3 is II in FIG.
FIG. 4 is a view taken in the direction of the arrow I, FIG. 4 is a view taken in the direction of the arrow IV-IV in FIG. 1, and FIG. Sixth
FIG. 7, FIG. 7, and FIG. 8 are cross-sectional views each showing a main part of an air-cooled engine according to another embodiment. 4… Engine, 11… Cylinder body, 12… Cylinder head, 11f, 12f, 12m… Cooling fin, 12b… (Cooling) base fin, 15… Crankshaft, 18… Generator,
19 cooling fan, 25 shroud, 25a left shroud part, 25b right shroud part, 26, 27 connecting part,
28 …… through hole, 29 …… exhaust port.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-176618 (JP, A) JP-A-2-201015 (JP, A) Fully open 1974-30737 (JP, U) Really open 1975 73329 (JP, U) Japanese Utility Model Showa 59-139514 (JP, U) Japanese Utility Model Application Hei 3-49324 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F01P 5/06 502

Claims (1)

(57) [Claims] A motorcycle equipped with an air-cooled engine so as to horizontally or forwardly tilt a cylinder body having cooling fins arranged on the outer periphery thereof has cooling fins erected on the surface of a cylinder head and orthogonal to the cylinder axis on the outer periphery. While forming a heat dissipating base fin extending in the direction in which the cooling fan rotates on the engine side by the engine power,
A shroud for guiding the cooling air of the cooling fan to the back surface of the cooling fins and the base fins of the cylinder body is mounted outside the cylinder body, and the shroud is provided at a position facing the cooling fan for suction. A left shroud portion provided with a hole and a right shroud portion provided with an exhaust port are provided, the right shroud portion is elastically supported on the engine body, and a connecting portion provided with the left shroud portion at a mating surface of both shroud portions. An air-cooled engine for a motorcycle, wherein the air-cooled engine is connected to the right shroud portion via the right and left shrouds and surrounds only the cooling fins of the cylinder body and the back surfaces of the base fins by the right and left shroud portions.