JP2002021548A - Muffler attaching structure for widely used engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attach a muffler onto an engine with supporting structure of high rigidity without increasing the number of part items such as a long bracket, and to prevent vibration and a strange noise such as a chattering noise in its turn from being generated without being accompanied with complication of the structure and increase of weight. SOLUTION: In this muffler attching structure for the widely used engine wherein an engine cylinder 10 is provided in an inclined condition inclined from a vertical direction in an engine mounted condition, and wherein the muffler 24 is is positioned in an upper side of the cylinder 10, a cooling cowl 20 for guiding cool air to the cylinder 10 is positioned in the periphery of the cylinder 10 and is fixed onto the engine in three or more of attaching portions, an exhaust pipe 26 is extended upwards from the cylinder 10, the muffler 24 is fixed to a tip of the exhaust pipe 26, and a lower side part of the muffler 24 and a cooling cowl 16 upper side part are fastend.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a muffler mounting structure for a general-purpose engine.

[0002]

2. Description of the Related Art In general-purpose engines used as various types of portable power sources and power sources for generators, a muffler is connected to an exhaust pipe (exhaust pipe) of the engine to muffle exhaust sounds. Conventionally, the muffler is attached by forming a wide flange at the end of the exhaust outlet of the exhaust pipe, and butting the end of the exhaust pipe to the exhaust inlet below the muffler.
A muffler is attached by tightening the bolts using a plurality of bolts (see JP-A-1998-266851, JP-A-2000-8842, and the like).

In addition, there is another type in which a plurality of brackets are protruded below the muffler, and the muffler is bolted to a boss provided on an engine crankcase.

[0004]

However, as described above, when the muffler is attached to the flange of the exhaust pipe,
The driving vibration of the engine is transmitted to the exhaust pipe to vibrate the muffler, and there is a disadvantage that the muffler generates a so-called chattering sound. Also, it is considered that a vibration provided to the muffler can be reduced by providing a plurality of brackets on the muffler and fastening the muffler to the crankcase. However, since the muffler is usually adjacent to the cylinder and not to the crankcase, it is necessary to attach a plurality of long brackets to the muffler to secure the rigidity of the mounting. Also, it is fastened to the crankcase with a plurality of fastening bolts. Therefore, there is a problem that the number of parts including the relatively large bracket increases and the weight tends to increase.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned conventional problems, and a muffler can be mounted on an engine with a highly rigid support structure without increasing the number of components such as a long bracket. It is an object of the present invention to provide a muffler mounting structure for a general-purpose engine, which can prevent the generation of noise such as chattering noise without complicating the structure and increasing the weight.

[0006]

The present invention has the following configuration to solve the above-mentioned problems. That is, the present invention provides a muffler mounting device for a general-purpose engine located above the cylinder portion, wherein the engine cylinder portion is provided in a state inclined from a vertical direction when the engine is installed. A cooling cowl that guides cooling air to the engine cylinder is positioned around the engine cylinder, fixed to the engine at three or more attachment points, an exhaust pipe is extended upward from the engine cylinder, and a muffler is fixed to the end of the exhaust pipe. A muffler mounting structure for a general-purpose engine, wherein a lower portion of the muffler and an upper portion of the cooling cowl are fastened.

According to the present invention, when installing and fixing the muffler in a general-purpose engine, the muffler is fixed (welded and fixed) to the end of the exhaust pipe, and the cooling cowl having high support rigidity supported by three or more support portions. Since the lower part of the muffler is fastened and fixed to the upper part, there is rigidity,
The vibration of the engine that reaches the muffler through the exhaust pipe can be suppressed by connecting the cooling cowl and the muffler. Therefore, the muffler can be firmly supported and fixed without using a long mounting member such as a plurality of brackets, and vibration of the muffler can be prevented, and noise such as chattering noise can be eliminated. In particular, if the cooling cowl is made of a thick plate so as to have sufficient rigidity, the rigidity is further increased, and the occurrence of vibration can be further prevented. Since the lower part of the muffler and the upper part of the cooling cowl are usually close to each other due to the demand for compact engines, the fastening parts such as bosses provided on the lower part of the muffler and the upper part of the cooling cowl can be reduced, and the weight can be reduced. Can be achieved.

In the present invention, a space is provided between the lower side of the muffler and the upper side of the cooling cowl when viewed from the tilt side of the cylinder portion of the engine, and the space is provided between the lower side of the muffler and the upper side of the cooling cowl. It is preferable that a fastening tool can be inserted into the fastening portion. This makes it easy to insert the tool into the fastening portion, thereby improving the workability and maintenance of the muffler.

Further, the spark plug is screwed to the upper side of the engine cylinder portion and installed. The fastening portion between the lower portion of the muffler and the upper portion of the cooling cowl is located at the position where the spark plug is installed when viewed from the tilt side of the cylinder. It is preferable to have a phase in the left-right direction. In this way, even if the spark plug is installed on the upper side of the cylinder, the spark plug or the high-pressure cord connected to it does not hinder the insertion of the tool,
Workability and maintenance of the muffler can be further improved.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 are explanatory views of a muffler mounting structure of a general-purpose engine according to an embodiment of the present invention. FIG. 1 is a view of the general-purpose engine as viewed from a cylinder inclined side of a crankshaft. 3 is a sectional view taken along the line II-II of FIG. 1 and a sectional view of the cylinder shaft viewed from the crankshaft output side. FIG.

As shown in FIGS. 1 to 3, the engine cylinder (hereinafter simply referred to as "cylinder") 10 is largely inclined from a vertical direction (for example, θ with respect to a horizontal line) in a normal installation state of the engine. <45 °
(Preferably θ <35 °) so as to protrude from the engine case 12. The engine is an engine case 1 having a substantially short cylindrical shape and rotatably accommodated in a crankshaft 14.
The crankshaft 14 has one end 14a protruding from the engine case 12 on the output side, and a cooling fan 16 mounted on the other end. A bowl-shaped fan cover 18 covering the periphery of the cooling fan 16 is fixed to the engine case 12.

[0013] The engine is air-cooled,
The periphery of the cylinder 10 is covered with a cooling cowl 20 having a substantially cylindrical shape. This cooling cowl 2
The space between the inner surface of the cylinder 0 and the outer periphery of the cylinder 10 is a cooling air passage 22 (see FIGS. 1 and 2). The outlet of the fan cover 18 is connected to the cooling air passage 22 so that the cooling fan 16 Guide cooling air efficiently to cylinder 10
, The cylinder 10 is cooled.
The cooling cowl 20 is provided at a plurality of locations (in the embodiment, as shown in FIGS. 1 to 3, at three points on the upper side, the lower side, and one side surface of the cylinder 10) by the bolts 20 a, 20 a, and 20 a. It is fixed to the case 12 to have rigidity. And it is made of a relatively thick plate material to give more certain rigidity.

The muffler 24 of the engine has a general box shape whose outer shape is aligned up and down, is installed above the cylinder 10, and is entirely covered by a cover 24a having a downwardly open square shape. An exhaust port 24b is open on the cylinder 10 side. The engine exhaust manifold 10b is provided on the crankshaft output side 14a at the top of the cylinder 10, and the exhaust outlet of the manifold 10b is bolted together with the flange 26a at the base end of the exhaust pipe 26 extending upward. It is put on and fixed. The upper end of the exhaust pipe 26 is fixed by welding to one end of the lower surface of the muffler 24 (the output side of the crankshaft 14). One part of the L-shaped plate is welded to the lower part (lower part) of the muffler 24, and the other part is directed downward to the boss 28.
As protruding.

A boss 30 is projected upward from the upper portion of the cooling cowl 20, and the boss 30 is connected to the muffler 24.
The lower boss 28 is overlapped and fastened with a bolt 32. A space 34 is provided between the lower part of the muffler 24 and the upper part of the cooling cowl 20 when viewed from the inclined side of the cylinder 10, and this space 34 is formed by a fastening bolt 32 between the lower part of the muffler 24 and the upper part of the cooling cowl 20. Into which a fastening tool can be inserted. And the cylinder head 10a
, An ignition plug 36 is screwed in a state substantially parallel to the axis of the cylinder 10 and at a slight angle.
The position 2 has a phase shifted from the installation position of the ignition plug 36 in the left-right direction when viewed from the inclined side of the cylinder 10.

A box-shaped fuel tank 38 is mounted on the upper part of the engine case 12 by a leg-shaped bracket, and is vertically aligned with the muffler 24 when viewed from the crankshaft direction. The air cleaner 40 is mounted on the non-output side in the crankshaft direction (see FIG. 2). The engine has a structure of a four-cycle OHV engine through which a push rod passes through a lower part in the cylinder. Fins are formed on a peripheral surface of the cylinder 10 to improve cooling efficiency.

According to the embodiment, when the muffler 24 is installed and fixed in a general-purpose engine, the muffler 24 is fixed to the tip of the exhaust pipe 26 (for example, by welding and fixing), and the cooling having high support rigidity supported by three or more support portions. Since the lower part of the muffler 24 is fastened and fixed to the upper part of the cowl 20, the rigidity is high, and the vibration of the engine that reaches the muffler 24 through the exhaust pipe 26 is suppressed by the connection between the cooling cowl 20 and the muffler 24. be able to. Therefore,
The muffler 24 can be firmly supported and fixed without using a long mounting member such as a plurality of brackets, so that the muffler 24 can be prevented from vibrating and, consequently, generating noise such as chattering noise. In particular, if the cooling cowl 20 is made of a thick plate so as to have sufficient rigidity, the rigidity is further increased, and the generation of vibration can be further prevented. Since the lower part of the muffler 24 and the upper part of the cooling cowl 20 are close to each other due to the demand for downsizing the engine, the fastening parts such as bosses provided on the lower part of the muffler 24 and the upper part of the cooling cowl 20 can be reduced. , Weight reduction can be achieved.

A space 34 is provided between the lower part of the muffler 24 and the upper part of the cooling cowl 20 when viewed from the inclined side of the cylinder 10. The space 34 is formed between the lower part of the muffler 24 and the upper part of the cooling cowl 20. Since the fastening tool can be inserted into the bolt fastening portion, the insertion of the tool into the fastening portion can be facilitated, and the workability and maintenance of the muffler 24 can be improved.

An ignition plug 36 is screwed to the upper side of the engine cylinder 10 and installed. The fastening portion between the lower side of the muffler 24 and the upper side of the cooling cowl 20 is connected to the cylinder 1
When the spark plug 36 is installed on the upper side of the cylinder 10, the spark plug 36 or the high-pressure cord 36a connected to the spark plug 36 is provided even if the spark plug 36 is installed on the upper side of the cylinder 10 because the installation position of the spark plug 36 is shifted in the left-right direction when viewed from the inclination side of 0. Does not hinder the insertion of the tool, and the assembling workability and maintainability of the muffler 24 can be further improved.

It should be noted that the muffler mounting structure of the general-purpose engine of the present invention is not limited only to the above-described example.
It goes without saying that various changes can be made without departing from the spirit of the present invention.

[0021]

As described above, according to the present invention, the vibration of the engine which is rigid and reaches the muffler through the exhaust pipe can be suppressed by the connection between the cooling cowl and the muffler. Therefore, the muffler can be firmly supported and fixed without using a long mounting member such as a plurality of brackets, and vibration of the muffler can be prevented, and noise such as chattering noise can be eliminated. In particular, if the cooling cowl is made of a thick plate so as to have sufficient rigidity, the rigidity is further increased, and the occurrence of vibration can be further prevented. Since the lower part of the muffler and the upper part of the cooling cowl are usually close to each other due to the demand for compact engines, the fastening parts such as bosses provided on the lower part of the muffler and the upper part of the cooling cowl can be reduced, and the weight can be reduced. Can be achieved.

In the present invention, a space is provided between the lower portion of the muffler and the upper portion of the cooling cowl when viewed from the inclined side of the cylinder, and this space is used for fastening the lower portion of the muffler and the upper portion of the cooling cowl. It is preferable that a fastening tool can be inserted into the portion. This makes it easy to insert the tool into the fastening portion, thereby improving the workability and maintenance of the muffler.

The ignition plug is screwed onto the upper side of the engine cylinder part, and the fastening part between the lower part of the muffler and the upper part of the cooling cowl is located at the position where the ignition plug is installed when viewed from the inclined side of the cylinder. It is preferable to have a phase in the left-right direction. In this way, even if the spark plug is installed on the upper side of the cylinder, the spark plug or the high-pressure cord connected to it does not hinder the insertion of the tool,
Workability and maintenance of the muffler can be further improved. This can provide an excellent effect.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a muffler mounting structure of a general-purpose engine according to an embodiment of the present invention, and is a view of the general-purpose engine as viewed from a cylinder tilt side of a crankshaft.

FIG. 2 is a sectional view taken along the line II-II of FIG. 1 and showing a cross section of the cylinder shaft as viewed from a crankshaft output side.

FIG. 3 is an explanatory view showing a state where a fan cover is removed when viewed from a direction III in FIG. 1;

[Explanation of symbols]

 Reference Signs List 10 engine cylinder 12 engine case 14 crankshaft 16 cooling fan 18 fan cover 20 cooling cowl 22 cooling air passage 24 muffler 26 exhaust pipe 28 boss (muffler side) 30 boss (cooling cowl side) 32 bolt 34 space 36 spark plug

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Nobunumi Yasumi 300 Suzuki Co., Ltd. Takatsukacho, Hamamatsu-shi, Suzuki F-term (reference) 3G004 AA06 AA07 BA02 DA12 DA15 EA06 GA01

Claims (3)

[Claims] In an installed state of an engine, an engine cylinder portion is provided to be inclined from a vertical direction, and a muffler is a muffler mounting device for a general-purpose engine located above the cylinder portion. A cooling cowl for guiding cooling air is positioned around the engine cylinder, fixed to the engine at three or more mounting points, an exhaust pipe is extended upward from the engine cylinder, and a muffler is fixed to the tip of the exhaust pipe. A muffler mounting structure for a general-purpose engine, wherein a lower portion of the muffler and an upper portion of the cooling cowl are fastened. 2. A space is provided between a lower portion of the muffler and an upper portion of the cooling cowl as viewed from the inclined side of the cylinder portion, and the space is fastened to a fastening portion between the lower portion of the muffler and the upper portion of the cooling cowl. 2. A muffler mounting structure for a general-purpose engine according to claim 1, wherein a mounting tool can be inserted. 3. A spark plug is screwed to an upper portion of an engine cylinder portion, and a fastening portion between a lower portion of the muffler and an upper portion of the cooling cowl is provided with a spark plug when viewed from the inclined side of the cylinder portion. 3. The muffler mounting structure for a general-purpose engine according to claim 2, wherein the position and the phase are provided in the left-right direction.