Internal-combustion engines – Frame construction – Horizontal cylinder
Utility Patent
1999-01-25
2001-01-02
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Frame construction
Horizontal cylinder
C123S19800E
Utility Patent
active
06167861
ABSTRACT:
FIELD OF THE INVENTION
This invention concerns a mounting configuration for an exterior insulating cover for the exhaust pipe on a small multipurpose single-cylinder engine.
BACKGROUND OF THE INVENTION
In recent years small multipurpose engines have been improved by being made lighter in overall weight and more compact to the point where they can be picked up and carried in one's hands. At the same time, various designs have been proposed for the insulating cover for the exhaust pipe, which becomes extremely hot when the engine is running.
In the prior art, such exhaust pipe covers were mounted to the engine using the following configurations.
(1) When the exhaust pipe was made from steel tubing
The cover was welded to the exhaust pipe to form an integral structure or the mounting fittings were welded to the pipe and the cover was fixed to the fittings by means of bolts or some similar hardware so that there was a gap between the cover and the pipe.
(2) When the exhaust pipe was made of cast iron
A mounting seat was provided on the engine cylinder, the cylinder head or the exhaust pipe. The cover was fixed to this mounting seat by means of bolts or some similar hardware with a gap between the pipe and the cover.
A practical example of the mounting configuration for such an exhaust pipe cover may be found in Patent Report
62-185833
. In this design, three shrouds are used: an upper shroud to cover the muffler; a lower shroud to cover the cylinder; and a lateral shroud (the exhaust pipe cover) to cover the exhaust pipe. The lower portion of the exhaust pipe cover is attached to the engine by bolts which also secure the lower shroud.
The parts of the engine which reach high temperatures, such as the cylinder head and the exhaust pipe, need to be shielded by protective covers so that the person using the engine will not be burned if he touches them. For small multipurpose engines in particular, the number of fittings must be kept low, and the fittings must be able to be mounted and removed simply in a small number of assembly processes. The construction of the fittings also must be simple, and they must be able to be made in a small number of manufacturing processes.
However, with the prior art techniques listed above, the exhaust pipe cover is either welded to the exhaust pipe or attached to it by means of a specialized bolt exclusively used for the exhaust pipe cover. This means that the cover, too, is likely to reach easily a high temperature, and its essential insulating function is compromised.
Also, the techniques described above require specialized components such as mounting fittings, which pushes the parts count upward. The process of manufacturing the mounting seat also increases the number of production processes.
Like the prior art techniques, the design disclosed in Japanese Utility Patent Publication (Kokai) 62-185833, also requires specialized components such as bolts to mount the exhaust pipe cover, which are exclusively used for mounting the pipe, and result in driving up the parts count. In addition to this disadvantage, the lower portion of the cover is fixed to the lower shroud, which is made of an insubstantial plate. The cover, then, is not securely supported, which can result in vibration and noise.
SUMMARY OF THE INVENTION
In view of these problems in the prior art, the object of this invention is to provide a mounting configuration for an exhaust pipe cover which reduces the parts count, reduces the number of production and assembly processes and lowers the cost. Such a configuration would reliably insulate the exhaust pipe without resulting in vibration and would provide a secure mounting for the cover.
To achieve these objects, the present invention provides a mounting configuration for the cover of an engine exhaust pipe which is distinguished by the following characteristics. This invention concerns the exhaust pipe of an engine in which a muffler is affixed to the outlet flange of an exhaust pipe whose inlet flange is connected to the exhaust outlet of the cylinder head. The cover which shields the exhaust pipe is affixed by the same means to the outlet flange of the pipe and to the bottom of the muffler together.
The upper flange of the exhaust pipe cover is affixed to both the bottom of the muffler and the outlet flange of the exhaust pipe together. Its front portion extends downward from the upper flange in such a way as to cover the exhaust pipe.
The exhaust pipe cover is made from a thin metal plate. The bolts securing the outlet flange of the exhaust pipe, which extends downward from the bottom of the muffler, hold fast both the bottom of the muffler and the outlet flange.
The upper flange of the exhaust pipe cover is virtually horizontal, and its front surface is virtually vertical. To enhance the structural integrity of the cover, ribs are provided which extend from the upper flange down the front surface.
According to this invention, the exhaust pipe cover is affixed to the bottom of the muffler and to the outlet flange of the exhaust pipe using the bolts that secure them to the engine body. No specialized hardware is, therefore, needed, so fewer parts are required than in prior art engines.
No special process is needed to mount the exhaust pipe cover. This reduces the number of manufacturing processes. The cover is easier to mount and remove, and the number of assembly processes is reduced.
As has been discussed earlier, the exhaust pipe cover is affixed to the rigid outlet flange of the exhaust pipe by the same means (bolts) that fasten it to the bottom of the muffler. This design assures that the cover is mounted securely and prevents the occurrence of vibration or noise. Furthermore, the upper flange of the exhaust pipe cover is securely affixed to both the outlet flange of the exhaust pipe and the muffler. This means that a large insulation distance can be maintained between the cover and the pipe, and that the contacting area of the cover receiving direct heat is small. As a result, the temperature of the cover can be kept relatively low, which improves the safety of the engine.
REFERENCES:
patent: 60-14224 U (1985-01-01), None
patent: 62-185833 U (1987-11-01), None
patent: 3-61538 U (1993-02-01), None
patent: 70-63037 (1995-03-01), None
Kobayashi Kazuyuki
Kouchi Hiroyoshi
Nakamura Shogo
Evenson, McKeown, Edwards & Lenahan P.L.L.C.
Kamen Noah P.
Mitsubishi Heavy Industries Ltd.
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