JPS60104714A - Forced air cooling engine - Google Patents

Abstract

PURPOSE:To dispose a fan in the close vicinity to a crank chamber wall and miniaturize an engine by providing the fan rotated integrally with a crank shaft between a magnet and the crank chamber wall, in the captioned device including the magnet provided on one end of the crank shaft. CONSTITUTION:For example, a forced air cooling single cylinder two cycle-engine 24 constituting a power unit 22 includes a flywheel magnet 46, a centrifugal automatic clutch 48, and a planetary gear type speed reducer 50 disposed in order on a crank shaft 32, and these members are covered with a case 52. The flywheel magneto 46 includes an outside rotor 46a fixed on the crank shaft 32 and a power generating coil 46b provided inside the aforesaid rotor. A fan 68 is additionally provided on the end surface of the rotor 46a on the crank chamber wall 26b side, i,e., on the opening edge of the rotor. The fan 68 is rotated together with the rotor 46a, and fresh air is sucked from an air intake port 70 and sent out from a cooling wind delivery port 72 into a wind guide cover 74. Hereby, a cylinder 28 can be cooled.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a forced air-cooled engine in which a magneto is provided at one end of the crankshaft.

(Prior art) In a forced air-cooled engine that has a fluffer (flywheel magneto) installed at one end of the crankshaft, a blower fan is conventionally installed on the opposite end of the fluffer from the crank chamber, and the cooling air sent out by this fan is used. is guided to the cylinder by an air guide cover that covers the cylinder.

When the fluffing fan is located between the blower fan and the crankcase in this manner, the air guide cover must also cover the fluffing fan, which poses a problem in that the air guide cover becomes large and the overall engine also becomes larger.

(Object of the Invention) The present invention was made in view of the above circumstances, and an object of the present invention is to provide a forced air-cooled engine suitable for downsizing.

(Structure of the Invention) To achieve this object, the present invention provides a forced air-cooled engine in which a magneto is provided at one end of the crankshaft. The air blower fan is provided to blow engine cooling air. Based on the example illustrated below.

The present invention will be described in detail.

(Embodiment) FIG. 1 is a side view of a small scooter to which an embodiment of the present invention is applied, FIG. 2 is a plan view of the moving crab knit, and FIG. 3 is a sectional view taken along the line l[I-III.

In FIG. 1, reference numeral 10 denotes a vehicle body frame, and a steering front wheel 16 is supported via a steering shaft 14 on a steering shaft cylinder 12 fixed to the front end of the vehicle body frame. 18 is a steering wheel, and 20 is a driver's seat.

22 is a moving crab knit. The forced air-cooled single-cylinder two-stroke engine 24 has a crankcase of 26° and cylinder 2.
8. It includes a piston 309, a cantilevered crankshaft 32, and the like.

On the opposite side of the crankcase 26 from the crankshaft 32,
A lid member 36 to which a reed valve 34 is attached is attached, and a carburetor 38 is attached to an intake pipe extending in the opposite direction to the crankshaft 32 to this lid member 36.

Reference numeral 40 denotes an intake air cleaner, which is formed to cover the carburetor 38, and has two intake chambers 40a inside.

A filter 42 is attached to partition 40b.

The carburetor 38 is located in one of the intake chambers 40a, and
The intake port No. 8 passes through the filter 42 and connects to the other intake chamber 40b.
Open to. Outside air enters through the opening 44 of the intake chamber 40a on the side of the carburetor 38, and passes through the filter 42° to the carburetor 38. Reed valve 3
4 into the crankcase 26.

The crankshaft 32 has an Aramag 46. Centrifugal automatic clutch 48. Planetary gear type reducers 50 are sequentially arranged coaxially and are covered with a substantially cylindrical case 52. Further, the output shaft 53 of the reducer 50 protrudes from the end of the case 52 on the opposite side to the crankshaft 32.

54 is a final reduction gear case, and a hub 60 of a rear wheel 58 is attached to a rear wheel shaft 56 supported by this case 54. The final reduction gear case 54 is connected to the case 52 of the moving crab knit 22 by a connecting cylinder 62, and a connecting shaft 64. The rotation of the output shaft 53 is transmitted to the rear wheel shaft 56 via the final reduction gear 66 inside the case 54 .

The fluffing plug 46 is of an outer rotor type and includes an outer rotor 46a fixed to the crankshaft 32 and a power generating coil 46b inside the outer rotor 46a. The generator coil 46b is fixed to a boss portion 26a that is integral with the crankcase 26 that holds the bearing of the crankshaft 32, and faces a permanent magnet fixed to the inner surface of the rotor 46a. A blower fan 68 is fixed to the end surface of the rotor 46a on the crank chamber side, that is, to the opening edge. The rotor 46a has a larger diameter than the crank chamber forming portion of the crankcase 26, and extends from the crank chamber wall 26b to the portion surrounding the rotor 46a.
An air intake lower 0 that opens on the inner diameter side of the fan 68 (boss 26a side) and a cooling air delivery lower 2 that opens on the outer diameter side of the fan 68 are formed.

Reference numeral 74 designates an air guide cover that covers the cylinder 28.

The cooling air delivery lower 2 opens into this cover 74.

In Fig. 2, 76 is an exhaust boat, which is connected to the delivery lower 2...[
Located at 1. This exhaust boat 76 has exhaust 'R78,
A muffler 80 is connected. The muffler 80 is located on the opposite side of the connecting cylinder 62, sandwiching the rear wheel 58.

This movable crab knit 22 is pivotally supported by the frame 10 so as to be able to swing up and down, and is supported by a buffer unit 82 (first
figure).

In this embodiment, the rotation of the crankshaft 32 causes the blower fan 68 to rotate clockwise in FIG. 3 together with the rotor 46a of the fluffer 46. The rotation of this fan 68 causes outside air to flow from the air intake lower 0 to the crank chamber wall 26a and the fluffer 4.
6, the cooling air is drawn in from the cooling air blowing lower 2 to the wind guiding cover 7.
4.

Therefore, the cylinder 28 is cooled. In this embodiment, since the exhaust boat 76 is located on the side of the cooling air delivery lower 2, the cooling performance near the high temperature exhaust boat is also improved.

In this embodiment, the blower fan 68 is provided directly on the rotor 46a, which is suitable for reducing the number of parts and simplifying the structure.
Of course, in the present invention, the blower fan may be provided independently of the fluffer. Further, the magneto may be of an inner rotor type in which a power generation coil is disposed outside the rotor.

(Effects of the Invention) As described above, the present invention provides a blower fan that rotates together with the crankshaft between the magneto provided at one end of the crankshaft and the crankcase wall, so that the blower fan approaches the crankcase wall. The wind guide cover is also smaller. Therefore, the overall size of the engine can be reduced.

[Brief explanation of drawings]

FIG. 1 is a side view of a scooter to which an embodiment of the present invention is applied, and FIG. 2 is a plan view of the moving crab knit. FIG. 3 is a sectional view taken along the line Irl-IJI. 24...Engine, 26b...Crank chamber wall. 32...Crankshaft, 46...Magneto. 46a...Rotor, 68...Blower fan. Patent applicant Yamaha Motor Co., Ltd. Agent Patent attorney Yama 1) Yu Moon

Claims (2)

[Claims] (1) In a forced air-cooled engine in which a magneto is provided at one end of the crankshaft, a blower fan that rotates integrally with the crankshaft is provided between the magneto and the crank chamber wall, and the blower fan generates engine cooling air. A forced air-cooled engine that features (2) The forced air-cooled engine according to claim 1, wherein the magneto is an outer rotor type flywheel magneto, and a blower fan is provided on the end face of the rotor on the crank chamber side.