Muffler of industrial engine

Abstract: The known muffler of an industrial engine is improved. A channel (4) communicating with an exhaust gas outlet (1b) is integrally formed on the inside of a muffler main body (1) made of an aluminium diecast, and an inner lid (2) is mounted to the open side of the channel (4) to form an exhaust gas passageway (5) serving also as a tail pipe, within the muffler main body (1). A cross-section area of the channel (4) is reduced gradually or in a stepwise manner from its inlet towards the exhaust gas outlet (1b) so as to prevent carbon from adhering to the exhaust passageway, and in that at the exhaust gas outlet (1b) a projecting wall (204) (fig.4) adapted to butt against the inner lid (2), is formed integrally with the muffler main body (1) so as to prevent the exhaust gas escape without passing through the exhaust gas passageway (5).

Description: BACKGROUND OF THE INVENTION: Field of the Invention: The present invention relates to a muffler of an industrial engine, and more particularly to improvements in a structure of such type of muffler. Description of the Prior Art: As the above-mentioned type of muffler, the inventor of this invention proposed previously in Japanese Utility Model JP-U-2 050 120, a structure of a muffler of an industrial engine, in which a channel communicating with an exhaust gas outlet is formed integrally on the inside of a muffler main body consisting of a diecast article, an inner lid consisting of a diecast or a sheet metal is joined to the open side of the aforementioned channel, and thereby an exhaust gas passageway serving also as a tail pipe is constructed within the muffler main body. Figs. 3 to 5 illustrate the muffler disclosed in the above-referred Japanese Utility Model JP-U-2 050 120, in which on the inside of a muffler main body 100 consisting of an aluminium diecast article having an exhaust gas inlet 100a and an exhaust gas outlet 100b, is formed a U-shaped channel 103 communicating with the exhaust gas outlet 100b by means of a wall 100c constructed integrally with the main body 100, and by joining and fastening, by means of a clamp screw 102, an inner lid 101 consisting of a diecast or a sheet metal on the opening side of the above-mentioned channel 103, an exhaust gas passageway 130 serving also as a tail pipe is constructed within the muffler main body 100, thus as compared to the structure in which a tail pipe is fixed to the exhaust gas outlet 100b of the muffler main body 100, shaping of the tail pipe is facilitated, and also by modifying the shape of the exhaust gas passageway, a path length from the inlet to the outlet can be arbitrarily changed, and tuning with respect to performance (output, noise) is made possible. However, the above-mentioned structure of a muffler in the prior art involved the following problems. That is, the inlet of the tail pipe is liable to be clogged by carbon because the exhaust gas passageway is abruptly choked and a flow velocity of the exhaust gas changes suddenly there, hence the tail pipe must be cleaned frequently, and also a curved portion of the exhaust gas passageway in the tail pipe is also apt to be clogged-by carbon, so that the time necessitating maintenance becomes frequent. SUMMARY OF THE INVENTION: It is therefore an object of the present invention to provide an improved muffler of an industrial engine, in which adhesion of carbon is little and maintenance is easy. According to the present invention, in a muffler of an industrial engine of the type that a channel communicating with an exhaust gas outlet is integrally formed on the inside of a muffler main body made of an aluminium diecast, and an inner lid is mounted to the open side of the channel to form an exhaust gas passageway serving also as a tail pipe, within the muffler main body, a cross-section area of the channel is reduced gradually or in a stepwise manner from its inlet towards the exhaust gas outlet. Owing to the above-featured construction, according to the present invention, since an inlet cross-section area of a tail pipe can be designed to be large, variation of a flow velocity of exhaust gas becomes relatively small, and also, since the flow velocity can be increased gradually or in a stepwise manner by reducing the cross-section area of the tail pipe gradually or in a stepwise-manner, carbon would hardly adhere to the exhaust gas passageway serving also as a tail pipe. The cross-section area of the above-mentioned channel can be easily reduced gradually or in a stepwise manner from its inlet towards the exhaust gas outlet by reducing a channel width or a channel depth of the channel gradually or in a stepwise manner. The above-mentioned and other objects, features and advantages of the present invention will become more apparent by reference to the following description of preferred embodiments of the invention taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS: In the accompanying drawings: Fig. 1 is a front view of a muffler according to a preferred embodiment of the present invention; Fig. 2 is a cross-section view taken along line A-A in Fig. 1 as viewed in the direction of arrows; Fig. 3 is a front view showing a muffler of an industrial engine in the prior art; Fig. 4 is a cross-section view taken along line C-C in Fig. 3 as viewed in the direction of arrows; and Fig. 5 is a cross-section view taken along line D-D in Fig. 3 as viewed in the direction of arrows. DESCRIPTION OF THE PREFERRED EMBODIMENTS: Now a preferred embodiment of the present invention will be described with reference to Figs. 1 and 2, Fig. 1 is a front view showing the inside of a muffler, and Fig. 2 is a cross-section view of an exhaust gas passageway. As seen from these figures, on the inside of a muffler main body 1 consisting of an aluminium diecast article is formed a U-shaped channel 4 communicating with an exhaust gas outlet lb by means of a wall 1c constructed integrally with the muffler main body 1. By joining and mounting an inner lid 2 made of a diecast or a sheet metal to the open side of the channel 4 and fastening them by means of a screw 3, and exhaust gas passageway 5 serving also as a tail pipe is formed within the muffler main body 1. At this time, the cross-section area of the exhaust gas passageway 5 is gradually reduced by appropriately positioning walls 1c, that is, by gradually reducing the channel width from an inlet width a to a width b , or by gradually reducing the channel depth from an appropriately set depth d to a shallower depth c or by combining these. The change of the cross-section area could be stepwise. As described above, according to this preferred embodiment, owing to the fact that the channel 4 communicating the exhaust gas outlet lb is integrally formed on the inside of the muffler main body 1 made of an aluminium diecast, the inner lid 2-consisting of a diecast or a sheet metal is mounted to the open side of the above-mentioned channel 4 to form the.exhaust gas passageway 5 serving also as a tail pipe within the muffler main body, and the cross-section area of the aforementioned channel 4 is reduced gradually or in a stepwise manner from its inlet towards the aforementioned exhaust gas outlet, the inlet cross-section area of the tail pipe can be made large, hence a variation of a flow velocity of the exhaust gas is relatively small, and clogging of the tail pipe by carbon would hardly occur. In addition, at a curved portion or a portion where a direction changes abruptly of the tail pipe or in the neighborhood of the portion, since it is possible to increase a flow velocity by gradually reducing the cross-section area of the tail pipe, carbon would be blown away and the tail pipe would be hardly clogged. Consequently, maintenance becomes easy.

Claims: A muffler of an industrial engine, in which a channel (4) communicating with an exhaust gas outlet (16) is integrally formed on the inside of a muffler main body (1) made of an aluminium diecast, and an inner lid (2) is mounted to the open side of said channel to form an exhaust gas passageway (5) serving also as a tail pipe, within the muffler main body (1); characterized in that a cross-section area of said channel (4) is reduced gradually or in a stepwise manner from its inlet towards said exhaust gas outlet (1b). A muffler of an industrial engine as claimed in Claim 1, characterized in that said channel (4) is U-shaped. A muffler of an industrial engine as claimed in Claim 1, characterized in that a channel width of said channel (4) is reduced gradually or in a stepwise manner. A muffler of an industrial engine as claimed in Claim 1, characterized in that a channel depth of said channel (4) is reduced gradually or in a stepwise manner.

Inventors: KATO TOMIYA C O NAGOYA MACH WO, KOBAYASHI YOSHIO NAGOYA MACH W, SATO TORU C O NAGOYA MACH WORK, KATO, TOMIYA, KOBAYASHI, YOSHIO, NAGOYA MACH.WORKS, MITSUBISHI, SATO, TORU, KATO, TOMIYA, C/O NAGOYA MACH.WORKS, MITSUBISHI, SATO, TORU, C/O NAGOYA MACH.WORKS, MITSUBISHI
Applicants: MITSUBISHI HEAVY IND LTD, MITSUBISHI JUKOGYO KABUSHIKI KAISHA
Application year: 1990
Main classification: F01N1
IPC codes: F01N7, F01N1