Endless belt power transmission systems or components – Fluid-impelling means
Reexamination Certificate
1999-09-03
2001-07-31
Bucci, David A. (Department: 3682)
Endless belt power transmission systems or components
Fluid-impelling means
C474S150000, C474S144000
Reexamination Certificate
active
06267700
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a cooling system for a power unit incorporating a V-belt transmission mounted on a vehicle such as a scooter etc.
(2) Description of the Prior Art
In a typical scooter, the engine and its power transmission for transmitting the engine's driving force to the rear wheel are held by a common housing forming an integrated power unit. As a power transmission for this power unit, a V-belt transmission T as shown in
FIG. 1
is known by which the engine force is transmitted from a drive pulley ‘b’ fixed on a crankshaft ‘a’ to a drive pulley ‘d’ fixed on a drive shaft ‘c’ on the driven side via a V-belt ‘e’.
In this power unit P, the engine's crankshaft, together with V-belt transmission T and other components, are accommodated within a common housing ‘g’ so that heat from the engine is subject to build up with in housing ‘g’. To avoid this, a power unit P of this type is provided with a cooling fan ‘f’ which is rotated by the engine's driving force so as to forcibly create a current of air and cool the air within housing ‘g’ by the air flow function of cooling fan ‘f’.
The above conventional power unit P, however, has suffered a problem in that cooling fan ‘f’ cannot create an efficient enough current of air within housing ‘g’ to provide sufficient cooling effects.
More specifically, in the conventional power unit P, the current of air created by the rotation of fan ‘f’ is conducted to an outlet air path ‘g
1
’ formed in the rear portion of housing ‘g’ as shown by the arrow in
FIG. 1
so that the hot air is discharged through an outlet port ‘g
2
’ that opens downwards. Therefore, the air conveyed to the rear portion will move in a direction opposite to the movement of V-belt ‘e’ in the rearmost portion, which will inhibit the flowability of the current of cooling air, resulting in degradation of cooling efficiency.
SUMMARY OF THE INVENTION
The present invention has been devised in view of the above prior art problems and it is therefore an object of the present invention to provide a cooling system for a vehicle power unit which facilitates efficient cooling inside a power unit.
In order to achieve the above object, the present invention is configured as follows:
In accordance with the first aspect of the present invention, a cooling system for a vehicle power unit incorporates: a V-belt transmission in which a drive pulley fixed on the crankshaft of an engine and a driven pulley fixed to the driven shaft linked with the wheel axle are arranged one behind the other and an endless V-belt is wound between the pulleys; and the crankshaft, in a housing thereof and includes: a cooling fan rotated by the rotational force from the crankshaft and disposed in the housing so as to cool the internal space of the housing by introducing air into the housing and discharging the introduced air to the outside through an outlet port; and
an upper side outlet port formed in the housing upper surface opposing the approximate middle portion of the V-belt's return path along which the V-belt moves from the rear to the front, and is characterized in that the current of air created by the cooling fan is flowed along the outgoing path of the V-belt moving from the front to the rear and then the air reaching the end of the outgoing path of the V-belt is flowed along the return path of the V-belt so as to discharge the air through the upper outlet port.
In accordance with the second aspect of the present invention, the cooling system for a vehicle power unit having the above first feature, further, comprises a lower side outlet port that opens downward, formed near the end of the outgoing path of the V-belt, and is characterized in that the current of air created by the cooling fan is flowed along the outgoing path of the V-belt and then part of the air reaching the end of the outgoing path is discharged from the lower side outlet port while the rest is further flowed along the return path of the V-belt and discharged from the upper outlet port.
In accordance with the third aspect of the present invention, the cooling system for a vehicle power unit having the above first feature is characterized in that an outlet air conduit duct for conducting the discharged air from the upper outlet port downward is joined to the upper outlet port.
In accordance with the fourth aspect of the present invention, the cooling system for a vehicle power unit having the above second feature is characterized in that an outlet air conduit duct for conducting the discharged air from the upper outlet port downward is joined to the upper outlet port.
In accordance with the invention described heretofore, the following effects can be attained.
In the present invention configured as above, as the crankshaft is rotationally driven by the engine, the cooling fan rotates. The current of air created by the rotation of the cooling fan flows along the outgoing path of the V-belt moving from the front to the rear, and then reaches the end of the outgoing path. The air further flows along the return path of the V-belt and discharged from the upper side outlet port together with heat generated from the engine, to the external space and thus the power unit is cooled. In this process, since the air flowing inside the housing moves along with the movement of the V-belt, efficient flow and discharge of air can be done markedly smoothly while preventing the air flow from being impeded by the V-belt, thus achieving efficient cooling.
In accordance with the second feature of the present invention, in addition to the upper outlet port, a lower side outlet port that opens downward is formed near the end of the outgoing path of the V-belt. In this arrangment, when the current of air created by the cooling fan is flowed along the outgoing path of the V-belt and reaches the end of the outgoing path, part of the air may be discharged from the lower side outlet port while the rest may be conveyed along the return path of the V-belt and discharged from the upper outlet port. Accordingly, this configuration makes it possible to secure an improved flowability of air inside the housing, thus achieving an excellent cooling efficiency.
When an outlet air duct for conducting the discharged air from the upper outlet port downward is jointed to the upper outlet air port, it is possible to prevent entrance of rainwater, dirt and dust etc. from the upper side outlet port into the housing.
REFERENCES:
patent: 4531928 (1985-07-01), Ikenoya
patent: 4631977 (1986-12-01), Kawashima
patent: 4671782 (1987-06-01), Ochiai et al.
patent: 4697665 (1987-10-01), Eastman et al.
patent: 4712629 (1987-12-01), Takahashi et al.
patent: 5976044 (1999-11-01), Kuyama
patent: 4241804 (1994-06-01), None
patent: 14362 (1997-01-01), None
patent: 262265 (1997-01-01), None
Bucci David A.
Charles Marcus
Darby & Darby
Suzuki Motor Corporation
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