Prime-mover dynamo plants – Miscellaneous – Drive gearing
Reexamination Certificate
2000-05-16
2001-12-18
Ponomarenko, Nicholas (Department: 2834)
Prime-mover dynamo plants
Miscellaneous
Drive gearing
C322S001000, C123S041560
Reexamination Certificate
active
06331740
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an engine generator unit including an engine and an electric-power generator driven by the engine.
2. Related Prior Art
Among general-purpose power supply devices suitable for use outdoors is the so-called engine generator unit which includes an engine and an electric-power generator driven by the engine. During operation, the engine, generator and muffler in the engine generator unit tend to become hot and thus are normally cooled via a cooling fan device. Typical examples of such an engine generator unit are shown in Japanese Utility Model Publication Nos. HEI-3-6831 and HEI-4-42494 and Japanese Patent Publication No. HEI-3-79532.
In the engine generator unit disclosed in Japanese Utility Model Publication No. HEI-3-6831, outside air is introduced into a space defined by the engine shroud, by means of a cooling fan device attached to the engine, in order to cool the engine cylinder and its vicinity. The outside or cooling air having cooled the engine cylinder is then passed through an exhaust air guide and blown onto the muffler while cooling an exhaust manifold, to thereby lower the temperature of the muffler. On the other hand, the outside air is also introduced into the generator by means of another cooling fan device attached thereto in order to cool the interior of the generator.
The engine generator unit disclosed in the No. HEI-4-42494 publication has a cooling fan device fixed to the engine, via which outside air is introduced into first and second cooling-air passages so that the engine cylinder is cooled by the air passing through the first cooling-air passage while the crankcase is cooled by the air passing through the second cooling-air passage. The air having cooled and passed the crankcase is then directed to cool the muffler.
Further, in the engine generator unit disclosed in the No. HEI-3-79532 publication, outside air is introduced, by means of a cooling fan device fixed to the engine, to cool both the engine and the generator, and the air having cooled and passed the engine and generator is directed to an exhaust air duct so as to cool the muffler provided within the exhaust air duct.
However, the first-mentioned prior engine generator unit disclosed in the No. HEI-3-6831 publication would require a great amount of cooling air in order to effectively cool the muffler because the muffler is cooled here by the cooling air after having passed the engine and hence having got relatively hot. Thus, arrangements must be made, in this unit, for directing as much cooling air as possible to the muffler with minimum leakage and for causing the cooling air to efficiently contact the muffler over the entire outer surface thereof. This is also the case with the second-mentioned prior engine generator unit. Further, the last-mentioned prior engine generator unit disclosed in the No. HEI-3-79532 publication would require a complicated cooling-air passage structure because of the arrangement that a great amount of the cooling air having passed the engine and generator is collected together and then directed to flow through the exhaust air duct.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to provide an improved engine generator unit which can cool the engine, generator and muffler with greatly increased efficiency by use of simple structure.
To accomplish the above-mentioned object, the present invention provides an engine generator unit which comprises: an engine; an electric-power generator to be driven by the engine, the engine and the electric-power generator being provided coaxially in a direction of an engine output shaft; a fuel tank disposed above the engine and electric-power generator; a muffler connected to an exhaust-discharging end of the engine and positioned above the engine adjacent the fuel tank; a heat blocking cover covering top and side portions of the muffler; a fan cover having a generally cylindrical shape, the fan cover covering the electric-power generator and extending close to the engine; and a cooling fan device disposed in a cooling-air inlet portion of the fan cover for introducing cooling air, from outside the engine generator unit, to the electric-power generator covered with the fan cover, an engine-cooling air passage having a cooling-air inlet portion that faces a cooling-air outlet portion of the fan cover being provided to cool an outer surface of the engine by the cooling air flowing out through the cooling-air outlet portion of the fan cover. In this inventive engine generator unit, the engine-cooling air passage is branched to provide a separate muffler-cooling air passage extending between the muffler and the heat blocking cover; thus, the cooling air introduced from the outside is allowed to cool both the engine and the muffler after having cooled the electric-power generator.
In the present invention, the cooling air introduced or sucked in via the cooling fan device first cools the generator within the fan cover, and then enters the engine-cooling air passage to cool the outer surface of the engine. By the engine-cooling air passage being branched upwardly to provide the separate muffler-cooling air passage as mentioned above, a proportion of the cooling air flowing out of the fan cover toward the engine-cooling air passage can be positively diverted into the muffler-cooling air passage between the muffler and the heat blocking cover and thereby can effectively cool the outer surface of the muffler. Because that proportion of the cooling air thus diverted into the muffler-cooling air passage has just cooled and passed only the electric-power generator and thus is still at a relatively low temperature, it can cool the muffler with sufficient efficiency. Namely, in the present invention, the cooling air introduced from the outside is allowed to first cool the electric-power generator and then both the engine and the muffler efficiently while still maintaining a low temperature.
In one preferred implementation, the engine-cooling air passage is provided, between the engine and an engine shroud covering at least a part of the engine, for passing therethrough the cooling air having cooled the electric-power generator, and the engine-cooling air passage is branched into the muffler-cooling air passage by means of an air guide provided on the engine shroud. Because the cooling air is directed to flow between the engine and the engine shroud, the engine can be cooled even more effectively. Further, with the air guide positively diverting a proportion of the cooling air flowing out of the fan cover, the cooling air can be directed into the muffler-cooling air passage with increased efficiency. Such an air guide can be of simple structure since it is only necessary for the air guide to divert the proportion of the cooling air within the engine shroud.
In a preferred embodiment of the present invention, the heat blocking cover is a dual-cover structure that comprises an inner cover covering the muffler with a predetermined first gap left therebetween and an outer cover covering the inner cover with a predetermined second gap left therebetween. The muffler-cooling air passage is made up of a first cooling-air path provided by the first gap and a second cooling-air path provided by the second gap and the second cooling-air path extends between the inner cover and the fuel tank. The diverted cooling air flows in the first cooling-air path of the muffler-cooling air passage along the inner surface of the inner cover, to thereby cool the outer surface of the muffler. The diverted cooling air also flows in the second cooling-air path of the muffler-cooling air passage along the outer cover, to thereby cool the outer surface of the inner cover. The cooling air flowing through the second cooling-air path functions as a heat blocking air layer, namely, an air curtain, that blocks the heat transfer from the inner cover. By the diverted cooling air thus flowing through the two cooling-air paths of the muffler-cooling air passage, the
Morohoshi Shinichi
Tsuru Ryuji
Adams & Wilks
Honda Giken Kogyo Kabushiki Kaisha
Ponomarenko Nicholas
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