JPH09170418A - Lublicating device for air-cooled four-cycle engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure lublication irrespective of operation posture of an engine by forming an oil reserving chamber having therein oil-mist generation means between a crank chamber and a recoil type starter, and then supplying the oil-mist generated in the chamber to respective parts of the engine such as the crank chamber. SOLUTION: During operation of an engine an oil slinger 25 of an oil reserving chamber 22 stirs lublicant through rotation of a crank 13 to generate oil mist. In accordance with rise of a piston the oil-mist is taken in a crank chamber 23 through a through hole 46 to Iublicate the crank 13 and a piston 8. Descending of the piston 8 followed by opening of a one-way valve 49 makes the oil-mist and the blow-by gas generated in the crank chamber 23 pass through a valve hole 48, a valve chamber 47 and a valve system chamber 24 to allow the oil-mist after being separated from the blow-by gas to lubricate a valve system 31. The oil-mist in the valve system chamber 24 is returned to the oil reserving chamber 22 via an oil returning chamber 50 and an uppermost chamber 56 while the oil liquefied in the valve system chamber 24 is returned to the oil returning chamber 50 and the oil reserving chamber 22 through an orifice. Such returning operation can be implemented in this way irrespective of the posture of an engine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a handheld four-cycle engine mainly used as a power source for trimmers and chainsaws, and more particularly to a shroud which covers the outer circumference of a cylinder block and defines a cooling air passage therebetween.
A cooling blade attached to one end of a crankshaft supported by the crankcase to send cooling air to a cooling air passage, and a recoil attached to the crankcase in a state of protruding to the outside of the shroud and capable of cranking the other end of the crankshaft. The present invention relates to a lubricating device for an air-cooled four-cycle engine equipped with a starter.

[0002]

2. Description of the Related Art As a conventional handheld engine, a two-cycle engine that can exhibit a lubricating function regardless of the engine operating posture such as tilting or overturning is widely used.

[0003]

However, in recent years, the adoption of a four-cycle engine as a handheld engine has been demanded from the viewpoint of exhaust gas purification. However,
In a four-cycle engine, it is necessary to store oil exclusively for lubrication, so if this oil is used in a handheld type, it is necessary to reliably lubricate each part of the engine regardless of the operating posture of the engine.

The present invention may satisfy such a need,
Moreover, it is an object of the present invention to provide a lubrication device for an air-cooled four-cycle engine, which is provided with an oil reservoir for storing lubricating oil and which can make the entire engine compact.

[0005]

In order to achieve the above-mentioned object, the present invention provides the above-mentioned air-cooled four-cycle engine,
A crankcase is provided between a crank chamber for accommodating a crank portion of a crankshaft and a recoil type starter, and forms an oil reservoir for storing lubricating oil. The oil mist generating means for generating oil mist by stirring is stored, and the oil mist generated in the oil reservoir is supplied to the crank chamber and other engine parts.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

FIG. 1 is a perspective view showing an example of use of a hand-held four-stroke engine provided with a lubricating device according to the present invention, FIG. 2 is a longitudinal sectional front view of the four-stroke engine, and FIGS.
FIG. 3 is a sectional view taken along line 3-3 to 9-9 in FIG.

First, as shown in FIG. 1, a hand-held four-stroke engine E is attached to a drive unit of the power trimmer T as a power source, for example. Power trimmer T
Is used by turning the cutter in various directions depending on the working state, so that the engine E is also greatly tilted each time,
Or, it is turned upside down, and the driving posture is not constant.

2 and 3, a carburetor 2 and an exhaust muffler 3 are respectively attached to the front and rear of an engine body 1 of the engine E, and an air cleaner 4 is attached to an inlet of the carburetor 2 at an intake path. . A fuel tank 5 is attached to the lower surface of the engine body 1. The carburetor 2 is provided with a diaphragm pump for pumping up fuel from the fuel tank 5 by utilizing pressure pulsation of a crank chamber described later of the engine E and returning excess fuel to the tank 5. Fuel can be supplied to the intake port of E.

Referring to FIGS. 2 and 3, an engine body 1 is shown.
Comprises a cylinder block 6 integrated with a head, and a crankcase 7 joined to a lower end surface of the cylinder block 6. The cylinder block 6 has a single cylinder 9 for accommodating a piston 8 at the center, and has a number of cooling fins 10 on its outer periphery.

The crankcase 7 comprises a pair of upper and lower case halves 7a and 7b, each of which has a plurality of bolts 11
The crankshaft 13 connected to the piston 8 via the connecting rod 12 is supported between the two case halves 7a and 7b as follows.

That is, the upper case half 7a has a pair of left and right upper journal walls 14, 14 'hanging from its ceiling wall.
And the lower case half 7b integrally includes a pair of left and right lower journal support walls 15 and 15 'that rise from the bottom wall and face the upper journal walls 14 and 14'. The left and right journal parts of the crankshaft 13 are sandwiched by the upper and lower journal support walls 14 and 15 through the plain bearing 16, and the right and left journals of the crankshaft 13 are supported by the upper and lower journal support walls 14 'and 15'. The parts are clamped via ball bearings 17. Upper and lower journal support walls 14, 14 '; 15, 1
5 ′ is provided with a total of four bolt holes 18 penetrating vertically through the crankcase 7 with the plain bearing 16 or the ball bearing 17 interposed therebetween. Stud bolts 19 are implanted in the lower end surface of the cylinder block 6. Nuts 20 are screwed onto the lower ends of these stud bolts 19 protruding from the lower surface of the crankcase 7, whereby the upper
The lower journal support walls 14, 14 '; 15, 15' are connected to each other, and the cylinder block 6 and the crankcase 7 are also connected to each other.

Since such a coupling structure does not interfere with the cooling fins 10 on the outer circumference of the cylinder block 6, the number and size of the cooling fins 10 can be freely selected.
The air cooling effect of the engine E can be sufficiently enhanced. In addition, the support rigidity of the crankcase 7 with respect to the crankshaft 13 can be increased.

Oil seals 21 and 21 'are mounted on both end walls of the crankcase 7 at portions penetrating through the crankshaft 13.

In the interior of the crankcase 7, the upper and lower journal supporting walls 14, 14 '; 15, 15' define an oil reservoir 22 on the left side, a crank chamber 23 in the center, and a valve operating chamber on the right side in FIG. The crank chamber 23 is provided with a crank portion 13 a of the crank shaft 13. A specified amount of lubricating oil O is stored in the oil reservoir 22 and is stirred and scattered by an oil slinger 25 (oil mist generating means).
Are fixed to the crankshaft 13.

As shown in FIGS. 2 and 4, the oil slinger 25 includes a boss 25a fitted to the crankshaft 13,
It is composed of a plurality of long arm blades 25b and a plurality of short arm blades 25c protruding from the outer periphery thereof, and both blades 25b, 2b.
The tips of 5c are bent in the axially opposite sides.

The oil slinger 25 having such a structure is
In any driving posture of the engine E, the blades 25
By rotating b and 25c, the oil stored in the oil reservoir 22 can be agitated to constantly generate the oil mist.

The valve operating chamber 24 extends through one side of the cylinder block 6 to its head, and the upper portion of the valve operating chamber 24 is opened and closed by a head cover 26 joined to the head of the cylinder block 6. It is possible.

As shown in FIGS. 2 and 5, suction and exhaust ports 27 and 28 connected to the carburetor 2 and the exhaust muffler 3 are formed at the head of the cylinder block 6, and these suction and exhaust ports are connected. Intake and exhaust valve 2 for opening and closing 27, 28
9 and 30 are provided, and a valve train 31 for opening and closing the intake and exhaust valves 29 and 30 is disposed in the valve train chamber 24.

The valve gear 31 includes a drive timing gear 32 fixed to the crankshaft 13 and a support shaft 3 supported between the joint surfaces of the cylinder block 6 and the crankcase 7.
4, a driven timing gear 33 rotatably supported by the drive timing gear 32 and driven at a half reduction ratio from the drive timing gear 32
And a cam 35 integrally connected to one end of the driven timing gear 33 and swingable by the cam 35.
A pair of cam followers 37 and 38 supported on a cam follower shaft 36 provided on the cylinder block 6 and a rocker shaft 39 provided on the head of the cylinder block 6 have one ends of the intake and exhaust valves 29 and 30, respectively. And a pair of rocker arms 40 and 41 abutting against the valve head of the cam follower 3 and the other ends of the rocker arms 40 and 41.
A pair of push rods 4 for connecting 7 and 38 respectively
2, 43, and valve springs 44, 45 for urging the intake and exhaust valves 29, 30 in the valve closing direction, respectively. The intake valve 29 is opened during the intake stroke of the piston 8, and the exhaust valve 30 is opened during the exhaust stroke. Can be opened.

The oil reservoir chamber 22 and the crank chamber 23 are communicated with each other through a through hole 46 formed in the crankshaft 13. At this time, the opening of the through hole 46 to the oil reservoir 22 is arranged in the center of the chamber 22, and the storage amount of the lubricating oil O in the chamber 22 is maintained even when the engine E is inclined or inverted. , The opening is set so as not to be submerged in oil.

As shown in FIGS. 2 and 7, a valve chamber 47 is formed on the lower surface of the crankcase 7 and is continuous with the valve operating chamber 24. The valve chamber 47 has a valve hole 48 through which a crank chamber 2 is formed.
3 communicates with the bottom. The valve chamber 47 is provided with a one-way valve 49 as a control valve for opening and closing the valve hole 48. The one-way valve 49 responds to pressure pulsation of the crank chamber 23, and closes the valve hole 48 when the pressure is reduced. It is designed to open it when boosting.

A U-shaped oil return chamber 50 surrounding the valve chamber 47 is formed on the lower surface of the crankcase 7, as shown in FIG. The oil return chamber 50 communicates with the bottom of the valve operating chamber 24 via a pair of orifices 51 arranged as far apart from each other as possible, and also communicates with the oil reservoir 22 via a pair of through holes. The total cross-sectional area of the through hole 22 is set sufficiently larger than the total cross-sectional area of the orifice 51.

The valve chamber 47 and the oil return chamber 50 are formed by closing a recess formed in the lower surface of the crankcase 7 with a bottom plate 53, and the bottom plate 53 is formed by the stud bolt 19 and the nut 20. It is fastened together with the crankcase 7.

The upper portion of the valve operating chamber 24 communicates with the inside of the air cleaner 4 via a rubber breather tube 54 attached to one side wall of the head cover 26 so as to penetrate therethrough. At this time, the valve train chamber 24 of the breather tube 54
The open end is disposed so as to protrude into the valve chamber 24 by a predetermined length. Therefore, in any operating posture of the engine E, it is possible to prevent the oil that somewhat accumulates in the valve train chamber 24 from flowing out to the breather tube 54.

As shown in FIGS. 2, 8 and 9, the head cover 26 has an outer cover 55 fitted to the outer periphery thereof.
Are combined. A flat uppermost chamber 56 is defined between the ceiling walls of the covers 26 and 55, and the chamber 56 is formed with a pair of orifices 57 (preferably at four corners) formed at diagonal positions of the ceiling wall of the head cover 26. Provided with the valve operating chamber 24. The uppermost chamber 56 is provided with one oil passage 58 formed in the cylinder block 6 and the crankcase 7.
Also communicates with the oil return chamber 50 via the. The oil passage 58
It has a cross-sectional area larger than the total cross-sectional area of the pair of orifices 57.

During the operation of the engine E, the rotation of the crankshaft 13 causes the oil slinger 2 in the oil reservoir 22 to rotate.
When 5 agitates the lubricating oil O to generate oil mist, when the crank chamber 23 is decompressed by the upward movement of the piston 8, the oil mist passes through the through hole 46 and the crank chamber 2
3 is inhaled and lubricates the crank portion 13a and the periphery of the piston 8. Next, when the crank chamber 23 is pressurized by the downward movement of the piston 8, the one-way valve 49 is opened to supply the oil mist together with the blow-by gas generated in the crank chamber 23 from the valve hole 48 to the valve chamber 47, and thus to the valve operating chamber 24. Then, the oil mist and blow-by gas are separated in the chamber 24. The oil mist lubricates each part of the valve train 31, and the blow-by gas blows the breather tube 54.
Through the air cleaner cleaner 4.

By the way, the pressure in the crank chamber 23 pulsates due to the up and down movement of the piston 5 so as to alternately repeat the positive pressure and the negative pressure. At the time of the positive pressure, the one-way valve 49 opens to release the positive pressure. At the time of negative pressure, the one-way valve 49 closes to prevent reverse flow of the positive pressure from the valve chamber 47, so that the pressure in the crank chamber 23 is maintained in a negative pressure state on average.

On the other hand, the valve operating chamber 24 and the valve chamber 4
Since 7 communicates with the inside of the air cleaner 4 at atmospheric pressure via the breather tube 54, the pressure in both chambers 24 and 47 is substantially atmospheric pressure.

Further, since the oil reservoir chamber 22 communicates with the crank chamber 23 through the through hole 46, the pressure of the oil reservoir chamber 22 becomes equal to or slightly lower than that of the crank chamber 23.

The oil return chamber 50 communicates with the oil reservoir chamber 22 through a through hole 52, while the valve train chamber 2 communicates through an orifice 51.
4, the oil return chamber 50 has a pressure equal to or slightly lower than the oil reservoir chamber 22.

The uppermost chamber 56 communicates with the oil return chamber 50 through the oil passage 58, and also communicates with the valve operating chamber 24 through the orifice 57, so that the pressure in the uppermost chamber 50 is the same as the oil return chamber 22. Or, the pressure becomes slightly lower than that.

The relation of pressure level in each chamber can be expressed by the following equation.

Pc≤Po≤Pr≤Pt <Pv where Pc: pressure in the crank chamber 23 Po: pressure in the oil reservoir 22 Pr: pressure in the oil return chamber 50 Pt: pressure in the uppermost chamber 56 Pv: valve operating chamber 24 As a result, during the operation of the engine, pressure flows through the following path.

[0035]

[Outside 1] Therefore, the oil mist sent to the valve operating chamber 24 is returned to the oil reservoir 22 via the pressure path, and the oil liquefied in the valve operating chamber 24 is passed to the oil return chamber 50 and the oil reservoir 22 via the orifice 51. And reflux. The oil mist and the liquefied oil are returned without any problem regardless of the inclination of the engine E.

Further, since the uppermost chamber 56 is located below the valve operating chamber 24 when the engine E is in the inverted operating state, the oil liquefied in the valve operating chamber 24 flows into the uppermost chamber 24 through the orifice 57 and returns through the oil passage 58. It is sucked up into the chamber 50 and is returned to the oil sump chamber 22.

In this way, the inclination of the engine E, the inversion, etc.
Regardless of the driving posture, the circulation of the lubricating oil is continuously performed inside the engine E, and a good lubricating state can always be ensured. Therefore, the power trimmer T can withstand operations in all directions. Moreover, since the circulation of the lubricating oil utilizes the pressure pulsation of the crank chamber 23,
No expensive oil pump is required.

Referring again to FIG. 2, the crankshaft 13
The rotor 61 with the cooling blades 60 of the flywheel magneto 59 is fixed to the outer end on the valve train chamber 24 side, and the ignition coil 62 cooperating with the rotor 61 is fixed to the cylinder block 6. A centrifugal clutch 64 is interposed between the rotor 61 and the working machine drive shaft 63. The centrifugal clutch 64 includes a plurality of clutch shoes 65 axially supported by the rotor 61 so that the diameter can be expanded, a clutch spring 66 for urging the clutch shoes 65 in a diameter reducing direction, and a clutch shoe 65 surrounding the clutch shoes 65 and fixed to the drive shaft 63. When the rotor 61 rotates at a predetermined number of revolutions or more, the clutch shoe 65 expands in diameter and comes into pressure contact with the inner peripheral surface of the clutch drum 67, so that the output torque of the crankshaft 13 is transmitted to the drive shaft. 63
To be communicated to.

A shroud 69 is attached to the engine body 1 to cover the head portion and the flywheel magnet 59 and to define a cooling air passage 68 between the head portion and the flywheel magnet 59. The shroud 69 is mounted between the centrifugal clutch 64 and the shroud 69. The inlet 68i of the passage 68 is provided in an annular shape, and the shroud 69 on the opposite side thereof is provided with an outlet 68o.

Oil reservoir 2 adjacent to one side of the crank chamber 23
2 is a cylinder block 6 so as to face the cooling air passage 68.
A known recoil starter 70, which is arranged so as to project from the outer side surface and is capable of cranking the crankshaft 13, is attached to the outer surface of the crankcase 7 on the oil reservoir 22 side. The starter 70 is arranged so as to project to the outside of the shroud 69 so that the operation of the starter rope is not interfered with by the shroud 69.

Thus, together with the crankshaft 13, the rotor 61
When is rotated, the wind generated by the cooling blades 60 flows through the cooling air passage 68 and cools each part of the engine E. In particular, since the oil reservoir chamber 22 faces the cooling air passage 68, this is also the above cooling. The lubricating oil O can be cooled effectively by being cooled by the wind. Moreover, since the oil sump chamber 22 is disposed in the space between the crank chamber 23 and the recoil type starter 70, which is conventionally a dead space, the presence of the oil sump chamber 22 does not cause the engine E to become large.

10 to 13 show the one-way valve 49.
Another embodiment of the present invention in which a rotary valve 71 is used instead of the above is shown. 10 to 12, the rotary valve 71
Is the cam 3 of the driven timing gear 33 of the valve gear 31.
5 has a pair of fan-shaped valve portions 72 formed on the side surface on the side opposite to 5 and arranged on the diameter line, and a pair of concave portions 73 sandwiched by these valve portions 72 in the circumferential direction. The valve hole 74 is formed so as to face the valve hole 74 formed in the partition wall between 24, and the valve hole 74 is opened and closed by the rotation of the driven timing gear 33.

Each of the valve portion 72 and the recessed portion 73 is approximately 90.
The drive timing gear 32 has a central angle of °, but the driven timing gear 33 rotates integrally with the crankshaft 13.
Since it is driven with a reduction ratio of 1/2, the closing period and the opening period of the valve hole 74 by the valve portions 72 and the concave portion 73 are approximately 180 ° when converted into crank angles.

Moreover, as shown in FIG. 13, the valve portion 72 and the recessed portion 73 are arranged so that the valve hole 74 is opened during the downward stroke of the piston 8 (see FIG. 12) and closed during the upward stroke (see FIG. 10). . A particularly desirable arrangement is to open the valve hole 74 in the range from the middle point P between the top and bottom dead centers of the piston 8 to 45 ° on the descending side of the piston 8 at the crank angle, and from the middle point P to the crank angle of the piston 8 at the crank angle. It is to close in the range of up to 45 °.

The other structure is the same as that of the previous embodiment except that the valve chamber 47 is omitted. In the figure, the same reference numerals are given to the portions corresponding to those of the previous embodiment.

Thus, the rotary valve 71 is the crankshaft 1
Since the valve hole 74 is opened and closed mechanically in conjunction with the rotation of No. 3, the predetermined opening and closing timing with respect to the valve hole 74 does not fluctuate even when the engine E rotates at high speed, and the inertia effect of the flowing gas is increased. Effectively utilize the crank chamber 23
The oil mist can be efficiently supplied to the valve operating chamber 24 from the above, and the average negative pressure state of the crank chamber 23 can be secured.

The present invention is not limited to the above embodiment, and various design changes can be made without departing from the scope of the invention. For example, the oil sump chamber 22 and the crank chamber 2
It is also possible to provide a through hole 46 communicating between the three with the plain bearing 16 or the partition wall between the two chambers 22 and 23. Further, the oil return chamber 50 may be eliminated and the valve operating chamber 24 may be directly communicated with the oil reservoir chamber 22 via the orifice 51, and the uppermost chamber 56 may be directly communicated with the oil reservoir chamber 22 via the oil passage 58. .
Further, the uppermost chamber 56 can be communicated with the crank chamber 23 via an oil passage 58.

[0048]

As described above, according to the first aspect of the present invention, the crankcase is arranged between the crank chamber for accommodating the crank portion of the crankshaft and the recoil starter and lubricated. Since the oil storage chamber for storing oil is formed, the space between the crankcase and the recoil type starter, which was conventionally a dead space, will be filled with the oil storage chamber integrated with the crankcase. However, the entire engine can be made relatively compact without increasing the number of parts.

Further, the oil mist generating means for generating the oil mist by stirring the lubricating oil is accommodated in the oil sump chamber, and the oil mist generated in the oil sump chamber is supplied to the crank chamber and other parts of the engine. Therefore, each part of the engine can be reliably lubricated by the oil mist in any operating posture of the engine.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a use state of a valve operating trimmer provided with an engine according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional front view of the engine.

FIG. 3 is a sectional view taken along line 3-3 in FIG. 2;

FIG. 4 is a sectional view taken along line 4-4 in FIG. 2;

5 is a sectional view taken along line 5-5 of FIG.

FIG. 6 is a sectional view taken along line 6-6 in FIG. 2;

FIG. 7 is a sectional view taken along line 7-7 of FIG. 2;

8 is a sectional view taken along line 8-8 of FIG.

9 is a sectional view taken along line 9-9 of FIG.

FIG. 10 shows another embodiment of the present invention and is a vertical cross-sectional view showing the rotary valve in a closed state.

11 is a sectional view taken along line 11-11 of FIG. 10;

FIG. 12 is a vertical sectional view showing the rotary valve in an open state.

FIG. 13 is a diagram showing the opening / closing timing of the rotary valve.

[Explanation of Codes] O Lubricating oil 6 Cylinder block 7 Crankcase 13 Crankshaft 13 Crank part 22 Oil sump chamber 23 Crank chamber 25 Oil slinger as oil mist generating means 60 Cooling blades 69 Shroud 70 Recoil starter

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] December 19, 1995

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] FIG.

[Correction method] Change

[Correction contents]

FIG. 13 ────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] January 24, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0030

[Correction method] Change

[Correction contents]

Further, since the oil reservoir chamber 22 communicates with the crank chamber 23 through the through hole 46, the pressure of the oil reservoir chamber 22 becomes equal to or slightly higher than that of the crank chamber 23.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction contents]

The oil return chamber 50 communicates with the oil reservoir chamber 22 through a through hole 52, while the valve train chamber 2 communicates through an orifice 51.
4, the oil return chamber 50 has the same pressure as the oil reservoir chamber 22 or a slightly higher pressure.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0032

[Correction method] Change

[Correction contents]

The uppermost chamber 56 communicates with the oil return chamber 50 through the oil passage 58, and also communicates with the valve operating chamber 24 through the orifice 57. Therefore, the pressure of the uppermost chamber 56 is the oil return chamber.
The pressure is equal to or slightly higher than 50 .

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction contents]

[0035]

[Outside 1] Therefore, the oil mist sent to the valve operating chamber 24 is returned to the oil reservoir 22 via the pressure path, and the oil liquefied in the valve operating chamber 24 is passed to the oil return chamber 50 and the oil reservoir 22 via the orifice 51. And reflux. The oil mist and the liquefied oil are returned without any problem regardless of the inclination of the engine E.

[Procedure Amendment 5]

[Document name to be amended] Drawing

[Correction target item name] Figure 3

[Correction method] Change

[Correction contents]

[Figure 3]

[Procedure correction 6]

[Document name to be amended] Drawing

[Correction target item name] Fig. 8

[Correction method] Change

[Correction contents]

[Figure 8]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sohei Honda, 1-4-1 Chuo, Wako-shi, Saitama, Ltd. Honda R & D Co., Ltd.

Claims (1)

[Claims] 1. A shroud (69) that covers the outer periphery of a cylinder block (6) and defines a cooling air passage (68) between the shroud and one end of a crankshaft (13) supported by a crankcase (7). Attached to the cooling vane (60) for sending cooling air to the cooling air passage (68), and the shroud (6)
9) An air-cooled four-cycle engine equipped with a recoil type starter (70) which is attached to the crankcase (7) in a protruding state to the outside and can crank the other end of the crankshaft (13). Is arranged between the crank chamber (23) in the case (7) accommodating the crank portion (7a) of the crankshaft (13) and the recoil starter (70) to store the lubricating oil (O). Forming an oil sump chamber (22),
An oil mist generating means (25) for stirring the lubricating oil (O) to generate an oil mist is housed in the oil sump (22), and the oil mist generated in the oil sump (22) is stored in the crank chamber. (23) A lubrication device for an air-cooled four-cycle engine, characterized in that it is supplied to other parts of the engine.