JP4504261B2 - Air-cooled engine with tilted cylinder - Google Patents

Description

  The present invention relates to an air-cooled engine with an inclined cylinder in which a mounting hole into which a fastening member can be inserted is provided at the lower part of a crankcase, and cooling fins are provided on the outer periphery of a cylinder block.

Some general-purpose air-cooled engines have a tilted cylinder. This air-cooled engine with an inclined cylinder includes cooling fins for air cooling on the outer periphery of a cylinder block in which the inclined cylinder is built (see, for example, Patent Document 1).
Japanese Utility Model Publication No. 58-19293

In the air-cooled engine with an inclined cylinder of Patent Document 1, a plurality of cooling fins are provided substantially orthogonal to the axis of the inclined cylinder on the outer periphery of the cylinder block.
According to this air-cooled engine with an inclined cylinder, air is allowed to flow between adjacent cooling fins to dissipate heat from the cooling fins and cool the cylinder.

In general, a general-purpose engine includes a base at a lower portion of a crankcase, and a mounting hole is provided in the base. Bolts are inserted into the mounting holes, and the general-purpose engine is attached to the mounting member with the inserted bolts.
Moreover, the casing of a general-purpose engine is an integrated crankcase and cylinder block, and a cast one is generally used.
In this casing, a cooling fin is provided on a cylinder block. And when casting a casing, after the molten metal in a cavity solidifies, a casting metal mold | die is opened along a cooling fin.

Here, since the plurality of cooling fins are provided substantially orthogonal to the axis of the tilt cylinder, the casting mold is opened in a direction substantially orthogonal to the axis of the tilt cylinder.
Therefore, the mold opening direction of the casting mold is different from the direction of the mounting hole. For this reason, when casting a casing, an attachment hole cannot be shape | molded simultaneously.
Therefore, after casting the casing, it is necessary to machine the mounting holes, which hinders productivity.

In order to solve this problem, a method is known in which a mold is provided with a slide mold, and the mounting hole is formed with the slide mold. By providing the mold with a slide mold, it is possible to form the mounting hole simultaneously when casting the casing.
However, this method has a problem that the mold needs to be provided with a slide mold and the structure of the mold becomes complicated.

  It is an object of the present invention to provide an air-cooled engine with an inclined cylinder that can simultaneously mold a mounting hole when molding a casing and can simplify the structure of a mold.

According to the first aspect of the present invention, the casing of the engine body is constituted by a crankcase that houses a crankshaft and a cylinder block provided with an inclined cylinder, and the casing is attached to the mounting member with a fastening member. In the air-cooled engine with an inclined cylinder provided with a mounting hole into which a fastening member can be inserted, and a cooling fin provided on the outer periphery of the cylinder block, a lower fin provided at a lower portion of the outer periphery of the cooling fin is connected to the mounting hole. A cooling fan that is formed parallel to the direction, blows cooling air from the crankcase side toward the lower fin, and raises the cooling air along the lower fin, and directs the lower fin in the vertical direction. It is characterized by having hit .

Of the cooling fins, the lower fin provided at the lower part of the outer periphery was formed in parallel to the direction of the mounting hole. Therefore, when the casing is formed, the mold opening direction of the mold can be matched with the direction of the mounting hole by opening the mold along the lower fin.
Thereby, when molding a casing with a metal mold | die, it becomes possible to shape | mold an attachment hole simultaneously.

In addition, by adjusting the mold opening direction of the mold to the direction of the mounting hole, the hole forming portion of the mounting hole can be formed integrally with the mold.
Thereby, since the slide mold | type conventionally required and the slide mechanism which slide-operates a slide mold | type can be removed from a metal mold | die, simplification of a metal mold | die can be achieved.

In addition , a cooling fan that blows cooling air from the crankcase side toward the lower fin and raises the cooling air along the lower fin is provided, and the lower fin is directed in the vertical direction.

By directing the lower fin in the vertical direction, the lower fin can be directed to the crankcase, that is, the cooling fan side.
Thereby, the cooling air blown from the cooling fan can be satisfactorily introduced into the lower fin, and the inclined cylinder can be efficiently cooled.

In addition, by attaching the lower fin in the vertical direction, the mounting hole also faces in the vertical direction. Therefore, the fastening member can be inserted into the mounting hole from above.
Thereby, the fastening operation of the fastening member is simplified, and the air-cooled engine with the inclined cylinder can be easily attached to the attachment member without taking time.

According to a second aspect of the present invention, the cooling fan has a lower end portion located below the lower fin, and blows cooling air from the lower end side toward the lower fin.

A lower end portion of the cooling fan is disposed below the lower fin, and cooling air is blown from the lower end side toward the lower fin. Therefore, it becomes possible to introduce the cooling air into the lower fin from the lower side of the lower fin, and the lower fin can be more suitably matched with the direction of the cooling air.
Thereby, the cooling air sent from the cooling fan can be introduced more satisfactorily by the lower fin, and the cooling effect of the tilt cylinder can be further enhanced.

According to a third aspect of the present invention, the cooling fin is oriented in a vertical direction from the lower fin to the axis of the inclined cylinder in a side view.

  The cooling fin was directed vertically from the lower fin to the axis of the tilt cylinder. Thereby, the cooling air led to the lower fin can be guided more smoothly along the cooling fin, and the cooling effect of the inclined cylinder can be further enhanced.

The air-cooled engine with an inclined cylinder according to the present invention has an advantage that the mounting hole can be simultaneously formed when the casing is formed with the mold by matching the mold opening direction of the mold with the direction of the mounting hole.
In addition, the air-cooled engine with an inclined cylinder according to the present invention has an advantage that it is not necessary to provide a slide mold for forming the mounting hole in the mold, and the mold can be simplified.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a front view showing an air-cooled engine with an inclined cylinder according to the present invention.
An air-cooled engine 10 with an inclined cylinder has an engine body 11 attached to a mounting base (attachment member) 12 with bolts (fastening members) 13... And a fuel tank 15, a muffler 16, and an air cleaner 17 on the upper part of the engine body 11.

The engine body 11 includes a casing 24 that houses the crankshaft 21 and the piston 23, and a base portion 25 is provided at a lower portion of the casing 24.
First and second mounting holes 26 and 27 are provided in the left end portion 25 a of the base portion 25. Further, third and fourth attachment holes 28 and 29 are provided in the right end portion 25 b of the base portion 25.

The bolts 13 are inserted into the first to fourth mounting holes (mounting holes) 26 to 29, and the base portion 25 is fixed to the mounting base 12 with the inserted bolts 13.
The casing 24 is a member made of an aluminum alloy having a crankcase 31 and a cylinder block 32 protruding from the right side portion of the crankcase 31.

A storage space 33 (see FIG. 2) is formed in the crankcase 31, and an inclined cylinder 35 is provided in the cylinder block 32.
The base portion 25 is provided at the lower portion of the crankcase 31.
The crankshaft 21 and the like are stored in the storage space 33, and the piston 23 is stored in the inclined cylinder 35. The piston 23 is rotatably connected to the crankshaft 21 by a connecting rod 36.

The storage space 33 is closed by bolting the case cover 38 to the crankcase 31. An end of the crankshaft 21, that is, a power take-off shaft (PTO shaft) 22 protrudes from the case cover 38.
The tilt cylinder 35 is obtained by tilting a cylinder axis (axis center) 39 from the crankcase 31 to an ascending gradient of the tilt angle θ.

2 is a perspective view showing a casing of an air-cooled engine with an inclined cylinder according to the present invention, and FIG. 3 is a view taken in the direction of arrow 3 in FIG.
The casing 24 includes a crankcase 31 and a cylinder block 32.
The crankcase 31 is provided with a peripheral wall 41 at the base portion 25 and a back wall 42 at the rear end of the base portion 25 and the rear end of the peripheral wall 41, so that the storage space 33 is formed by the base portion 25, the peripheral wall 41 and the back wall 42. Form.

First and second attachment holes 26 and 27 are provided in the left end portion 25a of the base portion 25 in the vertical direction (vertical direction).
Furthermore, third and fourth mounting holes 28 and 29 (see FIG. 4 for the fourth mounting hole 29) are provided in the right end portion 25b of the base portion 25 in the vertical direction (vertical direction).
The fourth mounting hole 29 is formed in the same shape as the second mounting hole 27.
The first and third attachment holes 26 and 28 are holes having openings formed in a circular shape.
The second and fourth attachment holes 27 and 29 are holes in which openings are formed as long holes.

A cylinder block 32 is integrally formed on the right side of the peripheral wall 41.
On the outer periphery 32a of the cylinder block 32, cooling fins 45 are formed over the entire periphery. The cooling fins 45 are composed of upper fins 46, lower fins 47, and a pair of side fins 48 (the rear side fins are not shown).
Since the pair of side fins 48 have the same shape, the side fins 48 on the near side will be described, and this description will be replaced with the description on the side fins 48 on the back side.

The side fins 48 are composed of inclined fin portions 51 from upper end portions 48a to bent portions 48b, and vertical fin portions 52 from bent portions 48b to lower end portions 48c.
The bent portions 48b are located below the cylinder axis 39 of the inclined cylinder 35 by a dimension H1 (see FIG. 1).

The inclined fin portion 51 is formed so as to be orthogonal to the cylinder axis 39 of the inclined cylinder 35. Therefore, the inclined fin part 51 is formed in the state inclined with respect to the vertical direction.
The vertical fin portion 52 is formed in a state directed in the vertical direction (up and down direction). Therefore, the vertical fin portion 52 is formed to face the same direction as the first to fourth mounting holes 26 to 29.
That is, the vertical fin portion 52 is formed in parallel to the directions of the first to fourth mounting holes 26 to 29.

FIG. 4 is a perspective view showing the positional relationship between the cooling fan and the cooling fin of the air-cooled engine with an inclined cylinder according to the present invention.
The air-cooled engine 10 with the tilt cylinder includes a cooling fan 58 on the back wall 42 side of the casing 24. The cooling fan 58 is provided on the crankshaft 21 (see FIG. 1).
By directing the lower fins 47 in the vertical direction, the lower fins 47 can be directed toward the crankcase 31 by an angle θ.
Therefore, the lower fins 47 can be directed to the cooling fan 58 side.

Here, the cooling fan 58 rotates in the clockwise direction as indicated by an arrow, and is configured to blow cooling air obliquely upward as indicated by an arrow from the lower end portion 58a toward the lower fins 47.
In addition, the cooling fan 58 has a lower end portion 58a located below the lower fins 47 by a dimension H2.
This makes it possible to introduce the cooling air into the lower fins 47 from the lower side of the lower fins 47, and to more suitably match the lower fins 47 with the direction of the cooling air.

Therefore, by rotating the crankshaft 21, the cooling fan 58 rotates as indicated by an arrow, and cooling air is blown from the cooling fan 58 toward the lower fins 47 as indicated by an arrow.
Since the lower fins 47 are directed toward the cooling fan 58, the cooling air blown from the cooling fan 58 can be satisfactorily introduced into the lower fins 47.
The cooling air introduced into the lower fins 47 is raised along the lower fins 47 as indicated by an arrow and guided to the outer periphery 32a of the cylinder block 32 (see FIG. 3). Therefore, the inclined cylinder 35 can be suitably cooled with the cooling air.

Here, when the flow of the cooling air is taken into consideration, it is preferable that the bent portions 48b of the side fins 48 are set at a high position so that the vertical fin portions 52 are secured large.
On the other hand, the entire length of the cylinder block 32 is L dimension. In order to arrange a large number of cooling fins 45 between the limited L dimensions, it is preferable to arrange the cooling fins 45 in a state orthogonal to the cylinder axis 39. This is because the width D of the cooling fin 45 can be kept small.

Therefore, in order to ensure a good flow of cooling air and to arrange a large number of cooling fins 45 in the cylinder block 32, the minimum value of the dimension H1 shown in FIG. 1 is set to 0 (zero).
By setting the minimum value of the H1 dimension to 0, the bent portions 48b... Have the same height as the cylinder axis 39.

Therefore, the side fins 48 are directed in the vertical direction from the lower fins 47 to the cylinder axis 39 in a side view. That is, the vertical fin portions 52 are the same size as the inclined fin portions 51.
By extending the vertical fin portions 52 to the cylinder axis 39, the bent fins 48b can be guided more smoothly along the cooling fins 47 than when the bent portions 48b are disposed below the cylinder axis 39.

In addition, it is possible to arrange a large number of cooling fins 45 in the cylinder block 32 by restraining the extension of the vertical fin portions 52 to the cylinder axis 39.
As described above, the cooling effect of the inclined cylinder can be further enhanced by arranging the plurality of cooling fins 45 along the cooling fins 47 so as to be more smoothly guided upward.

By the way, the 1st-4th attachment holes 26-29 are formed facing the up-down direction by orient | assigning the lower fins 47 ... to a perpendicular direction. Therefore, the bolts 13 can be inserted into the first to fourth mounting holes 26 to 29 from above.
As a result, the tightening operation of the bolts 13 is simplified, and the air-cooled engine 10 with the inclined cylinder can be easily attached to the mount 12 without taking time.

Hereinafter, a die casting mold for forming the casing 24 of the air-cooled engine 10 with the tilt cylinder will be described with reference to FIGS.
FIG. 5 is an exploded perspective view showing a die casting mold of an air-cooled engine with an inclined cylinder according to the present invention.
The die casting mold 60 includes a fixed mold 61 that molds the back portion 24 a of the casing 24, a movable mold 62 that molds the front portion 24 b of the casing 24, an upper slide mold 63 that molds the upper portion 24 c of the casing 24, and the casing 24. A right end slide mold 64 for forming the right end portion 24d and the tilt cylinder 35, a lower slide mold 65 for forming the lower portion 24e of the casing 24, and a left end portion slide mold 66 for forming the left end portion 24f of the casing 24 are provided.
The die casting mold 60 is a mold for die casting the casing 24.

The fixed mold 61 is a mold that includes a molding surface 61a that molds the back portion 24a of the casing 24, and that molds the side fins 48 on the back side with a part 61b of the molding surface 61a.
The movable mold 62 is a mold that can be closed (clamped) / opened in the direction of arrow A. The movable mold 62 is a mold that includes a molding surface 62a that molds the front portion 24b of the casing 24, and that molds the side fins 48 on the near side with a part 62b of the molding surface 62a.
The movable mold 62 is provided with a gate 68. The gate 68 is a flow path for supplying molten metal to the cavity 67 (see FIG. 8A).

The upper slide mold 63 is a mold that can be closed / opened in the direction of arrow B. The upper slide mold 63 is a mold that includes a molding surface 63a for molding the upper portion 24c of the casing 24, and molds the upper fins 46 with a part 63b of the molding surface 63a.
The right end slide mold 64 is a mold capable of closing / opening in the direction of arrow C. The right end slide mold 64 is a mold including a core 64 a for forming the tilt cylinder 35.

The lower slide mold 65 is a mold capable of closing / opening in the direction of arrow D. The lower slide mold 65 is a mold that includes a molding surface 65a for molding the lower portion 24e of the casing 24, and molds the base portion 25 and the lower fin 47 by a part 65b of the molding surface 65a.
The lower slide mold 65 includes first to fourth hole forming portions 65c to 65f on the molding surface 65a.

The first hole forming part 65 c is a part for forming the first mounting hole 26 in the base 25. The second hole forming part 65 d is a part for forming the second mounting hole 27 in the base 25.
The third hole forming part 65 e is a part for forming the third mounting hole 28 in the base 25. The fourth hole forming part 65f is a part for forming the fourth attachment hole 29 in the base 25 (see FIG. 4 for the fourth attachment hole 29).

  The left end slide mold 66 is a mold that can be closed / opened in the direction of arrow E. The left end slide mold 66 includes a molding surface 66 a for molding the left end 24 f of the casing 24.

As described with reference to FIG. 5, the first slide to the fourth mounting are attached to the lower slide mold 65 by aligning the mold opening direction of the lower slide mold 65 with the directions of the first to fourth mounting holes 26 to 29. It becomes possible to provide the 1st-4th hole shaping | molding site | parts 65c-65f which can shape | mold the holes 26-29.
Therefore, it is not necessary to provide the lower slide mold 65 with a slide mold for forming the first to fourth attachment holes 26 to 29.
Thereby, since the structure of the lower slide metal mold | die 65 can be simplified, the installation cost of the die-cast metal mold | die 60 can be held down.

FIG. 6 is an explanatory view showing an example in which the die casting mold according to the present invention is closed, and FIG. 7 is a sectional view taken along line 7-7 of FIG.
FIG. 6 shows a state in which the movable mold 62 is omitted for easy understanding of the configuration.
The casing 24 formed the vertical fin portions 52 of the cooling fins 45 so as to face the same direction as the first to fourth attachment holes 26 to 29.

On the other hand, the die-casting die 60 includes a portion 65b for forming the lower fins 47 ... on the forming surface 65a of the lower slide die 65, and first to first mounting holes 26 to 29 for forming the first to fourth mounting holes 26 to 29. 4 hole forming portions 65c to 65f.
Hereinafter, the portion 65b for forming the lower fins 47 is referred to as a lower fin forming portion.

The lower fins 47 are formed so as to face the same direction as the first to fourth mounting holes 26 to 29, similarly to the vertical fin portions 52.
The lower slide mold 65 is configured to open in the same direction as the direction of the vertical fin portions 52 and the direction of the first to fourth mounting holes 26 to 29, that is, the arrow D direction.

Therefore, after the molten metal in the cavity 67 shown in FIG. 8A is solidified, the lower slide mold 65 is opened as shown by the arrow D, so that the lower fin forming portion 65b is released from the lower fins 47 ... The first to fourth hole forming portions 65c to 65f are released from the first to fourth mounting holes 26 to 29, respectively.
Thereby, when the casing 24 is molded by the die casting mold 60, the first to fourth mounting holes 26 to 29 can be molded in the casing 24.

Next, an example in which the casing 24 is molded by the die casting mold 60 will be described with reference to FIG.
FIGS. 8A and 8B are views for explaining an example in which a casing is molded by the die casting mold according to the present invention.
In (a), with the die-casting mold 60 closed, a molten aluminum alloy is supplied to the cavity 67 from the gate 68 (see FIG. 5) of the movable mold 62 under high pressure.
When the molten metal in the cavity 67 is solidified, the upper fins 46 are formed by a part 63b of the molding surface 63a of the upper slide mold 63.

The lower fin 47 is formed by a part 65 b of the molding surface 65 a of the lower slide mold 65. The rear side fins 48 are molded by a part 61b (see FIG. 5) of the molding surface 61a of the fixed mold 61. The front side fins 48 are molded by a part 62b (see FIG. 5) of the molding surface 62a of the movable mold 62.
At the same time, the first to fourth mounting holes 26 to 29 are formed at the first to fourth hole forming portions 65 c to 65 f of the lower slide mold 65.
After the molten metal in the cavity 67 is solidified, the die casting mold 60 is opened.

Specifically, the movable mold 62 shown in FIG. 5 is moved in the mold opening direction. Further, the upper slide mold 63 and the right end slide mold 64 are moved in the mold opening direction as indicated by arrows B and C, respectively.
Further, the lower slide mold 65 and the left end slide mold 66 are moved in the mold opening direction as indicated by arrows D and E, respectively.

In (b), by opening the lower slide mold 65, the lower fin forming part 65b is released from the lower fins 47, and the first to fourth hole forming parts 65c to 65f are first to first. 4 from the mounting holes 26-29.
Thereby, when the casing 24 is formed by the die casting mold 60, the first to fourth mounting holes 26 to 29 can be simultaneously formed in the casing 24.

Here, aluminum die casting, in which the casing 24 is die-cast with an aluminum alloy, is a casting method in which a molten aluminum alloy is injected into a mold at a high pressure.
Thus, the molding precision of the casing 24 can be improved by die-casting the casing 24 with an aluminum alloy.

Therefore, at the time of die-casting the casing 24, for example, a portion where the heads (that is, the seating surfaces) of the bolts 13 shown in FIG. It is possible to mold a spot facing.
Thereby, after die-casting the casing 24, it is not necessary to machine a counterbore around the first to fourth mounting holes 26 to 29, and the productivity can be further enhanced.

Next, the flow of the cooling air of the air-cooled engine with an inclined cylinder will be described with reference to FIG.
FIG. 9 is a diagram illustrating an example in which cooling air is guided by the cooling fin according to the present invention.
The cooling fan 58 rotates as indicated by an arrow F, and cooling air is blown from the cooling fan 58 toward the lower fins 47 as indicated by an arrow G.
Since the lower fins 47 are directed toward the cooling fan 58, the cooling air blown from the cooling fan 58 can be satisfactorily introduced into the lower fins 47.

  The cooling air introduced into the lower fins 47 is raised along the lower fins 47 as indicated by an arrow H and guided to the outer periphery 32a of the cylinder block 32 (see FIG. 3). Therefore, the inclined cylinder 35 is suitably cooled with cooling air.

  In the above-described embodiment, the example in which the casing 24 is cast with an aluminum alloy die casting has been described. However, the present invention is not limited to this, and die casting with other materials is also possible.

  The present invention is suitable for application to an air-cooled engine with an inclined cylinder in which a mounting hole into which a fastening member can be inserted is provided in the lower part of the crankcase and cooling fins are provided on the outer periphery of the cylinder block.

1 is a front view showing an air-cooled engine with an inclined cylinder according to the present invention. It is a perspective view which shows the casing of the air-cooled engine with an inclination cylinder which concerns on this invention. FIG. 3 is a view taken in the direction of arrow 3 in FIG. 2. It is a perspective view which shows the positional relationship of the cooling fan and cooling fin of the air cooling engine with an inclination cylinder which concerns on this invention. It is a disassembled perspective view which shows the die-casting die of the air-cooled engine with an inclination cylinder which concerns on this invention. It is explanatory drawing which shows the example which closed the die-casting die concerning this invention. FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. 6. It is a figure explaining the example which shape | molds a casing with the die-casting die which concerns on this invention. It is a figure explaining the example which guide | induces cooling air with the cooling fin which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Air-cooled engine with an inclination cylinder, 11 ... Engine main body, 12 ... Mounting base (mounting member), 13 ... Bolt (fastening member), 21 ... Crankshaft, 24 ... Casing, 25 ... Base part (lower part of crankcase), 26 to 29: first to fourth mounting holes (mounting holes), 31: crankcase, 32: cylinder block, 32a: outer periphery, 35: inclined cylinder, 39: cylinder axis (axis), 45: cooling fin , 47 ... lower fins, 58 ... cooling fan, 58a ... lower end of the cooling fan.

Claims (3)

The casing of the engine body is composed of a crankcase that houses the crankshaft and a cylinder block that is provided with an inclined cylinder, and in order to attach the casing to the mounting member with a fastening member, the fastening member can be inserted into the lower part of the crankcase In an air-cooled engine with an inclined cylinder in which holes are provided and cooling fins are provided on the outer periphery of the cylinder block,
Of the cooling fins, a lower fin provided at the lower part of the outer periphery is formed in parallel to the direction of the mounting hole ,
A cooling fan that blows cooling air from the crankcase side toward the lower fin and raises the cooling air along the lower fin,
An air-cooled engine with an inclined cylinder, wherein the lower fin is directed in the vertical direction . The cooling fan has a lower end portion is positioned lower than the lower fins, inclined cylinder with air-cooled engine of claim 1, wherein the blowing cooling air toward the lower pins from the lower end. The air cooling engine with an inclined cylinder according to claim 1 or 2 , wherein the cooling fin is directed in a vertical direction from the lower fin to the axis of the inclined cylinder in a side view.

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