JP3439824B2 - Air-cooled internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air-cooled internal combustion engine (air-cooled engine) having cooling fins capable of uniformly cooling a cylinder and a cylinder head of an internal combustion engine with cooling air from a cooling fan directly connected to a crankshaft. And a water-cooled internal combustion engine).

[0002]

2. Description of the Related Art A shroud covers a cylinder and a cylinder head, which are heat radiating portions of an internal combustion engine, and cools air sucked from a shroud cooling air intake opening by rotation of a cooling fan integral with a crankshaft. An air-cooled internal combustion engine that cools the cylinder and the cylinder head by spraying the cooling fins (Japanese Utility Model Publication No. 63-32903)
Reference).

[0003]

In the air-cooled internal combustion engine described in the above publication, the cooling air sucked from the shroud cooling air intake opening is guided toward the cylinder head by the shroud. On the other hand, the cooling fins formed at right angles to the cylinder outer peripheral cooling fins could not smoothly flow toward the cylinder head, and the cylinders could not be cooled uniformly along the center line.

Further, in the vicinity of the outer periphery of the cooling fan in the shroud, one side of the plane passing through the center line of the crank and the center line of the cylinder is well exposed to the cooling air from the cooling fan, while the opposite side is exposed to the cooling air. Since the cooling air from the cooling fan is difficult to hit, it is difficult to cool the cylinder and the cylinder head uniformly over the entire circumference.

[0005]

SUMMARY OF THE INVENTION The present invention relates to an improvement of an air-cooled internal combustion engine which overcomes such difficulties.
The invention according to claim 1 includes a plurality of cooling fins provided on a cylinder and a cylinder head, a centrifugal cooling fan fitted to a shaft end of a crankshaft, and a shroud for covering the cylinder, the cylinder head and the centrifugal cooling fan. In an air-cooled internal combustion engine comprising:
The cooling fan is bent into a V shape near a boundary line parallel to the axis.
Fin is formed, or the cooling air outlet of the centrifugal cooling fan
The cooling air blown from the bottom of the V-shaped part of the cooling fin
It is characterized by directing toward a part .

[0006] The invention of claim 1 is configured as described above.
Therefore, it was blown out from the cooling air outlet of the centrifugal cooling fan.
Most of the cooling air going to the cylinder block is
Perimeter boundary of cylinder block closest to end of road
Since directed line vicinity of curved in a V shape on the boundary neighborhood
Most of the cooling air flows through the cylinder
Branched to the upper surface of the lock and the right side of the cylinder block
Is, cooling fins top facing towards the cylinder head, right
Since flows along the part, the cooling air without causing turbulence, smooth
Flows easily.

[0007] The centrifugal cooling fan causes
The cooling air blown into the inside of the
From the end opening of the inter-fin groove partitioned by the cooling fan
Flows smoothly along the sides of the

Further , according to the invention of claim 2 , the cooling is performed.
Cooling air blown from the outlet air blowing is slope of the cooling fins
It flows smoothly without causing turbulence along the oblique direction, as a result, before
The cylinder is uniform in both its axial direction and its circumferential direction.
Ku is efficiently cooled, high cooling performance.

Further, according to the invention of claim 3 , the system
The outside air outside the shroud is cooled by the centrifugal cooling fan.
The cylinder and cylinder head introduced into the loud
Blows smoothly to the cooling fins and cools them securely
be able to.

Further, according to the invention of claim 4, the centrifuge
Cooling fan along crank axis with respect to cylinder center line
It can be located at distant locations Te, the cylinder and far
Starter drive system one way crack between core cooling fan
Switches, generators, engine output, etc.
Can be compacted.

According to the invention of claim 5, the centrifugal cooling fan is provided.
From the cooling air outlet of the fan
Cooling air guided to the end opening of the groove between the fins,
The cooling fan is divided into two by a V-shaped curved cooling fin,
To flow along the fin between the grooves, a wide range of the cylinder peripheral surface
Can be uniformly cooled.

According to the invention of claim 6, the cooling fins
The cooling air held at low temperature without much heat exchange
Contact with the system and heated by heat transfer from the combustion chamber of the internal combustion engine
The air intake system that is apt to be cooled
Is retirement, the charging efficiency is maintained at a high level, moreover pressurized to a high temperature
The heated exhaust system concentrates on the exhaust vent and exhausts outside the shroud.
It is cooled sufficiently by the cooling air that is output.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention shown in FIGS. 1 to 7 will be described. The swing power unit 2 mounted on the scooter type motorcycle 1 (a three-wheeled or four-wheeled vehicle having one or two front wheels and two rear wheels is also possible) has a cylinder block 14 and a cylinder head 15 which are located in front of the vehicle. An air-cooled internal combustion engine 3 oriented slightly upward and a V-belt continuously variable transmission 4 oriented rearward from the left side of the air-cooled internal combustion engine 3 are integrally connected to each other to form a V-belt continuously variable transmission. The rear wheel 6 is integrally fitted to the output shaft 5 of the air-cooled internal combustion engine 3.
A pair of left and right hangers 7 located above the crankcase portion of the vehicle are mounted on a bracket 9 projecting downward from a rear frame 8 of the scooter type motorcycle 1 so as to be swingable up and down via a link 10 and a swing power unit. The rear portion of the swing power unit 2 is connected to the rear portion of the rear frame 8 via a shock absorber 11 so that the swing power unit 2 can swing up and down according to the ups and downs of the road surface during traveling.

As shown in FIG. 3, the swing power unit 2 includes a left crankcase 12 serving also as a left crankcase of the air-cooled internal combustion engine 3 and a transmission case of the V-belt type continuously variable transmission 4. A right crankcase 13, a cylinder block 14 integrally connected to the left crankcase 12 and the right crankcase 13, a cylinder head 15 connected to the top end of the cylinder block 14, and a detachable left side of the left crankcase 12. The fan cover 18 is divided into a transmission cover 16 (see FIG. 1) that can be freely mounted and a right cover 17 that is connected to the right side of the right crankcase 13 and covers a centrifugal cooling fan 26 described later. Removably mounted on the right side of the cylinder block 14 and the cylinder head 14
The upper and lower split cylinder shrouds 19 and 20 that cover 15 are fitted to the projections 21 of the cylinder head 15 and detachably attached to the left crankcase 12, right crankcase 13, right cover 17 and fan cover 18. Have been.

Further, a large number of cooling fins 23 and 24 are formed at predetermined intervals on the outer peripheral surfaces of the cylinder block 14 and the cylinder head 15, and a rotor 25 of a generator is provided at a right end of the crankshaft 22 in a right cover 17. A centrifugal cooling fan 26 is integrally attached to the rotor 25 inside the fan cover 18 while being fitted integrally.

Further, as shown in FIG. 4, the crankshaft 22 and the centrifugal cooling fan 26 rotate clockwise as viewed from the right side of the vehicle body.
The upper half portion of the cooling air passage 27 inside is formed in a spiral shape in a direction away from the center of the crankshaft 22 as it advances clockwise from the rear portion to the front portion via the upper portion and the right cover 17.
Also, a space 29 having a shape substantially similar to that of the cooling air passage 27 is formed by a partition wall 28 which is partially missing along the spiral direction.

Thus, the cooling fins of the cylinder block 14
As shown in FIG. 5, reference numeral 23 denotes a surface oriented in a direction of 45 ° to the upper right of the vehicle body from the cylinder center line of the cylinder block 14 (in FIG. 5, the left and right sides are reversed as viewed from the front of the vehicle body). As shown in FIG. 7, a cooling fin upper portion 23a above the boundary line Z is bent forward and leftward as shown in FIG. The cooling fin right side portion 23b below the boundary line Z is inclined at an angle of 45 ° toward the front and lower side of the vehicle body, as shown in FIG. The lower portion of the right cooling fin portion 23b is directed in the circumferential direction perpendicular to the cylinder center line, and the left and lower cooling fin left portion 23c and the lower cooling fin portion 23d of the cylinder block 14 are circumferentially curved. Orientation.

The cooling fins 24 of the cylinder head 15
All directions are directed in the circumferential direction perpendicular to the cylinder center line over the entire circumference.

Further, the suction opening 30 of the fan cover 18 is formed in a cylindrical shape concentric with the centrifugal cooling fan 26, and the louver 31 is fitted into the suction opening 30.

Further, an intake port 32 is formed on the upper surface of the cylinder head 15, and an exhaust port (not shown) is formed on the lower surface of the cylinder head 15.
And an exhaust pipe 34 is connected to the exhaust port, and an intake port 32 is provided on the upper surface of the upper cylinder shroud 19.
An opening 35 is formed in alignment with (see FIG. 3), and an opening 36 is formed in the lower surface of the lower cylinder shroud 20 in alignment with the exhaust port, and as shown in FIG. , It is located on the left side (the left and right sides are reversed because Fig. 5 is viewed from the front) and the exhaust port is directed to the right.
37 is open.

Since the embodiment shown in FIGS. 1 to 7 is constructed as described above, the centrifugal cooling fan 26 is driven to rotate clockwise in FIGS. , The suction opening of the fan cover 18 on the right side of the vehicle
The cooling air sucked in from the cooling air passage 30 is sent from the lower part through the rear part and the upper part in the cooling air passage 27 to the cylinder shrouds 19 and 20 in the direction of the arrow as shown in FIGS.

Most of the cooling air flowing toward the cylinder block 14 is directed to the vicinity of the boundary Z of the outer periphery of the cylinder block 14 which is closest to the terminal end portion 27a of the cooling air passage 27. Most of the cooling air is branched into the upper surface of the cylinder block 14 and the right side surface of the cylinder block 14 by the cooling fins 23 curved in a shape, and the cooling fin upper portion 23a and the right portion 23b face the cylinder head 15. The cooling air flows smoothly along the cooling fins 23a on the upper surface of the cylinder block 14, and the cooling air flows along the cooling fin left side portion 23c before cooling. The cooling air flows along the lower portion 23d of the fin, flows downward along the right side portion 23b of the cooling fin, merges with the cooling air flowing along the lower portion 23d of the cooling fin, and is discharged from the air outlet 37.

The cooling air flowing along the cylinder shrouds 19 and 20 reaches the outer peripheral portion of the cylinder head 15 and flows along cooling fins 24 oriented in a direction perpendicular to the center line of the cylinder block 14, and the cooling air flows therein. Some cooling air flows to the lower surface of the cylinder block 14 bypassing the upper surface and the left side surface of the cylinder block 14, and the remaining cooling air reaches the lower surface of the cylinder block 14 along the right side of the cylinder block 14, Both are discharged from the exhaust port 37.

As described above, the cooling air is supplied to all the cooling fins 23 and 24.
Cooling fins for smooth flow without turbulence
Cylinder block 14, cylinder head 15 via 23, 24
Is cooled uniformly throughout.

The intake pipe 33 is connected to the end 27a of the cooling air passage 27.
, The intake pipe 33 is cooled by the cooling air maintained at a low temperature without heat exchange with the cooling fins 23 and 24 to the left, and the filling efficiency is maintained at a high level.

Further, since the cooling exhaust air which has cooled the cylinder block 14 and the cylinder head 15 in the cylinder shrouds 19 and 20 blows onto the exhaust pipe 34 from the exhaust port 37, the exhaust pipe 34 heated to a high temperature is cooled. Cooled by wind.

[0027]

[Brief description of the drawings]

FIG. 1 is a left side view illustrating a rear half of a scooter type motorcycle equipped with a swing power unit incorporating an embodiment of an air-cooled internal combustion engine according to the present invention.

FIG. 2 is an enlarged side view of a main part of FIG.

FIG. 3 is a vertical cross-sectional plan view of the cylinder shroud and the fan shroud taken along the line III-III in FIG. 1;

FIG. 4 is an enlarged right side view of a main part of FIG. 2 with a fan cover removed.

FIG. 5 is a view taken in the direction of arrows VV in FIG. 3;

FIG. 6 is a view taken in the direction of arrows VI-VI in FIG. 3;

FIG. 7 is a view as viewed from the arrow YO in FIG. 5;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Scooter type motorcycle, 2 ... Swing power unit, 3 ... Air-cooled internal combustion engine, 4 ... V-belt type continuously variable transmission,
5 output shaft, 6 rear wheel, 7 hanger, 8 rear frame, 9 bracket, 10 link, 11 shock absorber, 12
... left crankcase, 13 ... right crankcase, 14 ... cylinder block, 15 ... cylinder head, 16 ... transmission cover, 17 ... right cover, 18 ... fan cover, 19, 20 ... cylinder shroud, 21 ... projection, 22 ... Crankshafts, 23,24 ... Cooling fins, 25 ... Rotor, 26 ... Centrifugal cooling fan, 27 ... Cooling air passage, 28 ... Partition wall, 29 ... Space, 30 ... Suction opening, 31 ...
Louver, 32 ... intake port, 33 ... intake pipe, 34 ... exhaust pipe, 35, 36
... opening, 37 ... air vent.

Continuation of the front page (72) Inventor Tomofumi Kuramitsu 1-4-1, Chuo, Wako-shi, Saitama Pref. Honda Technology Laboratory Co., Ltd. (56) References JP-A-5-71340 (JP, A) 40137 (JP, U) Japanese Utility Model Showa 49-136928 (JP, U) Japanese Utility Model Application Hei 5-66221 (JP, U) Japanese Utility Model Showa 63-136928 (JP, Y1) (58) Field surveyed (Int. Cl. ⁷ , DB name) F01P 1/05 F01P 5/06 502 F01P 5/06 511 F02F 1/06

Claims (6)

(57) [Claims] A plurality of cooling fins provided on a cylinder and a cylinder head; a centrifugal cooling fan fitted to a shaft end of a crankshaft; and a shroud for covering the cylinder, the cylinder head and the centrifugal cooling fan. In an air-cooled internal combustion engine, an axis of the cylinder
The cooling fin is bent into a V shape near the parallel boundary line and
Formed and blown out from the cooling air outlet of the centrifugal cooling fan
Cooling air is directed to the bottom of the V-shaped portion of the cooling fin.
An air-cooled internal combustion engine characterized by directing . 2. The cooling fin has a longitudinal direction in which
Air-cooled internal combustion engine according to claim 1, characterized in that the inclined cross at a small angle to the flow direction. 3. The cooling air suction port of the centrifugal cooling fan is
Opened from the cooling fan to the outside end of the crankshaft , the centrifugal cooling
The cooling air outlet of the cooling fan is located outside the outer circumference of the cooling fan.
Radial direction and oriented in a direction parallel to the cylinder center line.
Characterized in that an opening toward the cylinder Te claim 1 Symbol
Air-cooled internal combustion engine of the placement. 4. The cooling air outlet of the centrifugal cooling fan is provided at a front side.
Away from the side of the cylinder by the crankshaft.
The air-cooled internal combustion engine according to claim 1, wherein the internal combustion engine is arranged . 5. The cooling fin is provided with a centrifugal cooling fan.
Most of the cooling air blown out from the cooling air outlet is
Through the part reaching the outer peripheral surface of the cylinder,
2. The air-cooled internal combustion engine according to claim 1 , wherein the air-cooled internal combustion engine is curved in a V-shape at a boundary line parallel to the boundary . 6. The air-cooled internal combustion engine has a centrifugal cooling air intake system.
On the cooling air outlet side of the fan and the exhaust system on the opposite side.
And the exhaust port of the shroud is an exhaust pipe of an exhaust system.
2. The air-cooled internal combustion engine according to claim 1 , wherein the air-cooled internal combustion engine is opened toward the engine.