JP4366204B2 - Air-cooled engine - Google Patents

Description

    The present invention relates to an air-cooled engine.

  As a conventional air-cooled engine, as in the present invention, a fan case is provided at the front of the cylinder block, a ventilation path is provided rearwardly from the fan case, and this ventilation path is provided along the peripheral wall of the cylinder head, above the cylinder head. The exhaust muffler's muffler main body is arranged, the exhaust introduction pipe is led out downward from this muffler main body, the outlet end of this exhaust introduction pipe is attached to the rear surface of the cylinder head, and this exhaust introduction pipe is connected to the rear exhaust port of the air passage. Some of them have a tube cover attached to the rear side of the exhaust introduction pipe facing the rear side (see, for example, Patent Documents 1 and 2).

  In these prior arts, unlike the present invention, the rear exhaust port of the ventilation path is covered with the tube cover and there is no exposed portion to the rear.

JP 2001-90522 A (see FIG. 7) Japanese Unexamined Patent Publication No. 2002-2313 (see FIG. 3)

These conventional techniques have the following problems.
<Problem> Reduces the cooling efficiency of the cylinder head.
When this engine is mounted on a mower, foreign matter such as cut grass that has entered the fan case and has passed through the ventilation path is received by the tube cover and is not smoothly discharged from the rear exhaust vent. Reduce the cooling efficiency of the cylinder head.

  An object of the present invention is to provide an air-cooled engine that can solve the above-described problems, that is, an air-cooled engine that can suppress a decrease in cooling efficiency of a cylinder head.

(Invention of Claim 1)
As illustrated in FIG. 2 or FIG. 3, a fan case (2) is provided at the front portion of the cylinder block (1), a ventilation path (3) is provided rearward from the fan case (2), and the ventilation path (3 ) Along the peripheral wall (4a) of the cylinder head (4), the muffler body (5a) of the exhaust muffler (5) is disposed above the cylinder head (4), and the exhaust introduction pipe ( 5b) is led downward, and a lead-out end (5c) of the exhaust introduction pipe (5b) is attached to the rear surface of the cylinder head (4), and the exhaust outlet (5b) is passed through the ventilation path (3). In an air-cooled engine with (3a) facing from the rear side and a pipe cover (6) attached to the rear side of the exhaust introduction pipe (5b),
As illustrated in FIG. 1, a part of the rear exhaust port (3 a) of the ventilation path (3) is exposed to the rear side of the tube cover (6) ,
As illustrated in FIG. 2, the rear plate (6a) of the pipe cover (6) is separated from the rear peripheral surface of the exhaust introduction pipe (5b), and the rear plate (6a) is constituted by a flat plate along the vertical direction. The side plate (6b) is bent forward from both side edges (6d) of the back plate (6a), and the bent edge (6c) of both side plates (6b) is exhausted when the tube cover (6) is viewed from the side. Retreat to a position where it does not overlap the tube (5b),
As illustrated in FIG. 4A, both side plates (6b) are spread outward from both side edges (6d) of the back plate (6a),
As illustrated in FIG. 5B, the rear plate (6a) of the tube cover (6) is fixed to the exhaust introduction pipe (5b) via the spacer (5d), and the upper edge of the rear plate (6a) ( 6e) is connected to the lower edge of the body cover (7) attached to the muffler body (5a),
The cooling air blown to the pipe cover (6) after passing through the rearward air passage (3) is guided by the pipe cover (6), and is formed between the rear part of the muffler main body (5a) and the rear part of the main body cover (7). An air-cooled engine characterized by flowing into a rear ventilation gap (7d) formed therebetween.

(Invention of Claim 2 )
In the invention of claim 1 ,
As illustrated in FIG. 1, the air-cooled engine is characterized in that the back plate (6 a) of the tube cover (6) has a narrow shape with a wide upper portion and a narrow lower portion.

(Invention of Claim 3 )
In the invention of claim 1 or claim 2 ,
As illustrated in FIG. 5B, an air-cooled engine having an insulating sheet (8) sandwiched between the ceiling wall (7a) of the main body cover (7) and the muffler main body (5a).

(Invention of Claim 1)
The invention of claim 1 has the following effects.
<Effect> A decrease in the cooling efficiency of the cylinder head can be suppressed.
As is clear from the illustration of FIG. 1, a part of the foreign matter such as cut grass that has entered the fan case (2) and has passed through the ventilation path (3) is not received by the tube cover (6), but the rear exhaust port. Since the air is smoothly discharged rearward from (3a), foreign matter such as cut grass is hardly clogged in the ventilation path (3), and a decrease in cooling efficiency of the cylinder head (4) due to this clogging can be suppressed.

<Effect> Accumulation of foreign matter such as cut grass between the tube cover and the exhaust pipe is suppressed.
As is clear from the illustration of FIG. 2, foreign matter such as cut grass received by the tube cover (6) is smoothly blocked from both sides of the tube cover (6) without being obstructed by both side plates (6b). Since it is discharged, accumulation of foreign matter such as cut grass between the tube cover (6) and the exhaust introduction tube (5b) is suppressed.

<Effect> It has a high ability to suppress the accumulation of cut grass.
As is apparent from the illustration of FIG. 4A, foreign matter such as cut grass received by the tube cover (6) moves along the slope of the outward spread of both side plates (6b). Since it is discharged smoothly from both sides, the function of suppressing accumulation of foreign matter such as cut grass is enhanced.

<Effect> Damage to the connecting portion between the muffler body and the exhaust pipe due to vibration is suppressed.
As is apparent from the illustration of FIG. 5B, the connecting portion (5e) between the muffler main body (5a) and the exhaust introduction pipe (5b) is reinforced by connecting the back plate (6a) and the main body cover (7). Therefore, damage to the connecting portion (5e) between the muffler body (5b) and the exhaust introduction pipe (5b) due to vibration is suppressed.

(Invention of Claim 2 )
In addition to the effects of the first aspect of the invention, the following effects can be obtained.
<Effect> The reinforcing function is high, and the accumulation suppressing function of foreign matter such as cut grass is also high.
As is clear from the illustration of FIG. 1, the upper part of the back plate (6a) is wide, so that the connection between the back plate (6a) and the body cover (7) becomes strong, and the muffler body (5a) and the exhaust introduction pipe The reinforcing function of the connecting part (5e) with (5b) is high. Further, since the lower part of the back plate (6a) is narrow, it is difficult to receive foreign matter such as cut grass, and the function of suppressing the accumulation of foreign matter such as cut grass is high.

(Invention of Claim 3 )
In addition to the effect of the first or second aspect of the invention, the following effect can be obtained.
<Effect> The temperature rise above the ceiling wall of the main body cover can be suppressed.
As is clear from the illustration of FIG. 5B, a part of the cooling air that has passed through the ventilation path (3) passes from the side of the tube cover (6) by the amount from the tube cover (6) to the body cover (7). ) The amount of cooling air introduced into the interior decreases, and the cooling efficiency of the muffler body (5a) decreases, but the heat transfer from the muffler body (5a) to the body cover (7) is obstructed by the heat insulating sheet (8). Therefore, the temperature rise above the ceiling wall (7a) of the main body cover (7) can be suppressed.

Embodiments of the present invention will be described with reference to the drawings.
FIGS. 1 to 5 are views for explaining an air-cooled engine according to an embodiment of the present invention. In this embodiment, an inclined air-cooled gasoline engine is used for explanation.

The outline of this engine is as follows.
As shown in FIG. 1, the cylinder block (1) is composed of a crankcase (9) and a cylinder (10), and the cylinder (10) protrudes obliquely upward from the crankcase (9). A cylinder head (4) is attached to the protruding end of the cylinder (10), and a head cover (11) is attached to the cylinder head (4). A fuel tank (12) is disposed above the crankcase (9), and an exhaust muffler (5) is disposed above the cylinder head (4).

The outline of the air cooling device of this engine is as follows.
As shown in FIG. 2, a fan case (2) is provided at the front of the cylinder block (1), a ventilation path (3) is provided rearwardly from the fan case (2), and the ventilation path (3) is connected to the cylinder head. The muffler body (5a) of the exhaust muffler (5) is arranged above the cylinder head (4) along the peripheral wall of (4), and the exhaust introduction pipe (5b) is led downward from the muffler body (5a). The lead-out end portion (5c) of the exhaust introduction pipe (5b) is attached to the rear surface of the cylinder head (4), and the exhaust introduction pipe (5b) is passed from the rear side to the rear exhaust port (3a) of the air passage (3). The pipe cover (6) is attached to the rear side of the exhaust introduction pipe (5b).

The specific configuration of the air cooling device is as follows.
As shown in FIG. 2, a recoil case (13) is attached to the front portion of the fan case (2), an outside air inlet (14) is provided on the peripheral wall of the recoil case (13), and the fan case is provided from the outside air inlet (14). (2) Outside air can be introduced inside. As shown in FIG. 1, a rearward ventilation path (3) is formed by an upper airflow cover (15). The upper wind guide cover (15) is composed of a head side wind guide cover (15a) and a cylinder side wind guide cover (15b), and the head side wind guide cover (15a) is arranged at an oblique upper periphery of the cylinder head (4). The wall (4a) is covered obliquely from above, and the cylinder side wind guide cover (15b) covers the oblique upper peripheral wall and a part of the rear peripheral wall of the cylinder (10). The head-side air guide cover (15a) of the upper air guide cover (15) forms the rearward ventilation path (3) along the oblique upper peripheral wall (4a) of the cylinder head (4). A part of the rear exhaust port (3a) of the ventilation path (3) is exposed to the rear side of the tube cover (6).

  As shown in FIG. 1, the cylinder side wind guide cover (15b) forms an L-shaped cross section along the oblique upper peripheral wall and rear peripheral wall of the cylinder (10). The ventilation path along the peripheral wall of the cylinder (10) is led backward from the fan case (2) along the oblique upper peripheral wall of the cylinder (10), and from the leading end along the rear peripheral wall of the cylinder (10). Derived diagonally below. A part of the rear exhaust port (3a) of the rear ventilation passage (3) is exposed rearward from between the cylinder side wind guide cover (15b) and the tube cover (6). A lower wind guide cover (16) is disposed obliquely below the upper wind guide cover (15). The lower air guide cover (16) covers the oblique lower peripheral wall and a part of the rear peripheral wall of the cylinder (10). The lower air guide cover (16) forms an L-shaped air passage along the oblique lower and rear peripheral walls of the cylinder (10). The ventilation path along the peripheral wall of the cylinder (10) is led backward from the fan case (2) along the oblique lower peripheral wall of the cylinder (10), and obliquely along the rear peripheral wall of the cylinder (10) from the lead-out end. Derived above.

The specific configuration of the tube cover (6) is as follows.
As shown in FIG. 2, the rear plate (6a) of the pipe cover (6) is separated from the rear peripheral surface of the exhaust introduction pipe (5b), and the rear plate (6a) is constituted by a flat plate along the vertical direction. The side plate (6b) is bent forward from both side edges (6d) of the plate (6a), the tube cover (6) is viewed from the side, and the bent edges (6c) of both side plates (6b) are connected to the exhaust pipe. (5b) is retracted to a position that does not overlap. As shown in FIG. 4A, both side plates (6b) are spread outward from both side edges (6d) of the back plate (6a). As shown in FIG. 5 (B), the back plate (6a) of the tube cover (6) is fixed to the exhaust introduction pipe (5b) via the spacer (5d), and the upper edge (6e) of the back plate (6a) is fixed. ) Is connected to the lower edge of the body cover (7) attached to the muffler body (5a). The spacer (5d) protrudes rearward from the rear peripheral surface of the exhaust introduction pipe (5b). As shown in FIG. 1, the back plate (6a) of the tube cover (6) has a narrow shape with a wide upper portion and a narrow lower portion. The back plate (6a) has an inverted triangular shape.

The specific structure of the main body cover (7) is as follows.
As shown in FIGS. 4A and 4B, the main body cover 7 is composed of an upper cover 7b and a lower cover 7c. The upper cover (7b) has a rectangular bowl shape, and the lower cover (7c) has a rectangular dish shape. As shown in FIG. 5B, the bottom wall of the muffler body (5a) is covered from below with the lower cover (7c), and the other wall of the muffler body (5) is covered with the upper cover (7b). The body cover (7) is fixed to the muffler body (5a). The upper edge portion (6e) of the rear plate (6a) of the tube cover (6) is connected to the lower edge portion of the rear wall of the upper cover (7b). As shown in FIG. 5A, a ventilation gap (7d) is provided around the muffler body (5a).

As shown by the arrow in FIG. 5B, the cooling air that has passed through the rearward air passage (3) and blown onto the tube cover (6) is guided by the tube cover (6), and the muffler body (5a ) Flows into the rear ventilation gap (7d) formed between the rear part and the rear part of the body cover (7), and passes through the left and right ventilation gaps (7d) as shown by arrows in FIG. 5 (A). However, it also flows into the front ventilation gap (7d). Part of the cooling air flowing into the rear ventilation gap (7d) passes through the left and right ventilation gaps (7d), reaches the front ventilation gap (7d), flows out from here, and the rest The air flows directly downward from the left and right ventilation gaps (7d). As shown in FIG. 5 (A), a T-shaped ventilation groove (7e) is provided on the upper wall of the muffler body (5) so that a part of the cooling air passes through it as indicated by an arrow. Yes. As shown in FIG. 5B, a heat insulating sheet (8) is sandwiched between the ceiling wall (7a) of the main body cover (7) and the muffler main body (5a), and the ventilation groove (7e) is formed by the heat insulating sheet (8). Is covered from above. This heat insulating sheet (8) is a glass fiber sheet.

1 is a rear view of an inclined air-cooled engine according to an embodiment of the present invention. It is an II directional arrow line view of FIG. FIG. 3 is a view in the direction of arrow III in FIG. 1. 4A and 4B are diagrams for explaining an exhaust muffler with a cover used in the engine of FIG. 1, in which FIG. 4A is a plan view, and FIG. 4B is a view in the direction of arrow B in FIG. FIG. 5A is a combination of a cross-sectional view of the main body cover taken along the line VA-VA in FIG. 4B and a plan view of the muffler main body, and FIG. 5B is a VB-VB line in FIG. It is the figure which combined the cross-sectional view of the main body cover and tube cover, and the rear view of the exhaust muffler.

  (1) ... Cylinder block, (2) ... Fan case, (3) ... Ventilation path, (3a) ... Rear exhaust port, (4) ... Cylinder head, (5) ... Exhaust muffler, (5a) ... Muffler body, (5b) ... exhaust pipe, (5c) ... leading end, (5d) ... spacer, (5e) ... connecting part, (6) ... tube cover, (6a) ... back plate, (6b) ... side plate, (6c): bent edge, (6d): side edge, (7): body cover, (7a): ceiling wall, (8): heat insulating sheet.

Claims (3)

A fan case (2) is provided at the front of the cylinder block (1), a ventilation path (3) is provided rearwardly from the fan case (2), and the ventilation path (3) is connected to the peripheral wall (4a) of the cylinder head (4). ), The muffler body (5a) of the exhaust muffler (5) is disposed above the cylinder head (4), and the exhaust introduction pipe (5b) is led downward from the muffler body (5a) to introduce the exhaust. The lead-out end (5c) of the pipe (5b) is attached to the rear surface of the cylinder head (4), and the exhaust introduction pipe (5b) is passed through the rear exhaust port (3a) of the air passage (3) from the rear side. In an air-cooled engine with a pipe cover (6) attached to the rear side of the exhaust introduction pipe (5b),
A part of the rear exhaust port (3a) of the ventilation path (3) is exposed to the rear side of the tube cover (6) .
The rear plate (6a) of the tube cover (6) is separated from the rear peripheral surface of the exhaust introduction pipe (5b), and the rear plate (6a) is constituted by a flat plate extending in the vertical direction, on both sides of the rear plate (6a). The side plate (6b) is bent forward from the edge (6d), the tube cover (6) is viewed from the side, and the bent edges (6c) of both side plates (6b) do not overlap the exhaust introduction pipe (5b). Retract to position ,
Spread both side plates (6b) outward from both side edges (6d) of the back plate (6a) ,
The back plate (6a) of the tube cover (6) is fixed to the exhaust introduction pipe (5b) via the spacer (5d), and the upper edge (6e) of the back plate (6a) is attached to the muffler body (5a). is connected to the lower edge of the cover (7),
The cooling air blown to the pipe cover (6) after passing through the rearward air passage (3) is guided by the pipe cover (6), and is formed between the rear part of the muffler main body (5a) and the rear part of the main body cover (7). An air-cooled engine characterized by flowing into a rear ventilation gap (7d) formed therebetween. The air-cooled engine according to claim 1 ,
An air-cooled engine characterized in that the back plate (6a) of the tube cover (6) has a narrow shape with a wide upper portion and a narrow lower portion. The air-cooled engine according to claim 1 or 2 ,
An air-cooled engine characterized in that a heat insulating sheet (8) is sandwiched between a ceiling wall (7a) of a main body cover (7) and a muffler main body (5a).

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