JPH1136860A - Cooling device for 4-cycle engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cool an engine inside securely however large the engine may be inclined. SOLUTION: In an oil reservoir 18 cooled by a blower, partitioned from a crank case 16, the first air leading-in pipe and the second air leading-in pipe 22 which are opened at about the central position on a three-dimensional space are provided. When the oil reservoir 18 is made in the negative pressure, the outer air with a low temperature is lead in to the oil reservoir 18 through the first air leading-in pipe 20, and when the crank case 16 is made in the negative pressure, the air in the oil reservoir 18 is lead in the direction of the crank case 16 through the second air leading-in pipe 22. By using a mixing means 70 provided on the way of the oil feeding route from the oil reservoir 18 to the crank case 16, the air from the second air leading-in pipe 22 and the oil are mixed and led in to the crank case 16, so as to cool the inside of a 4-cycle engine E.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling system for a four-stroke engine, particularly a small four-stroke engine mounted and used in a hand-held sprayer, brush cutter, or the like.

[0002]

2. Description of the Related Art Sprayers and bush cutters (trimmers) for plants and trees
The hand-held working machine represented by the above is required that the worker can work without taking an uncomfortable posture. Accordingly, the engine that is the driving source of the working machine is required to have a capability of operating stably at any angle. The two-stroke engine has a mechanism that utilizes the negative pressure generated when the piston rises to draw lubricating oil into the engine together with fuel and lubricate each movable part, so that a structure that can be used at any angle is easy. Is realized. Therefore, a small and lightweight two-stroke engine having excellent tilt performance has been widely used for the above-mentioned working machine. On the other hand, general four-stroke engines can be made smaller and lighter due to advances in design and processing techniques. However, oil is stored in an oil sump (oil pan) provided at the lower part of the crankcase, and then jumps up from there. Since a mechanism is used to lubricate each movable part by pumping or pumping, it must basically be used upright. That is, the lubrication mechanism of the four-stroke engine is a factor that the four-stroke engine has inferior tilt performance as compared with the two-stroke engine.

[0003]

However, the two-stroke cycle engine has problems such as a large amount of hydrocarbons in the exhaust gas and a large amount of noise. There is a demand for the use of a good and low-noise 4-cycle engine for hand-held work equipment.
There is a demand for the development of a four-stroke engine having excellent tilt performance so that the operator can work at any angle. This four-stroke engine with excellent tilt performance has a hermetic structure, so it is difficult for heat to radiate, and it is important to adjust the heat balance of each part, but by actively introducing air from the outside, If a mechanism that cools the engine is provided, a good heat balance in the engine is maintained for a long time, and smoother engine operation is realized.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a cooling system for a four-stroke engine in which the engine is reliably cooled even in any inclined state.

[0005]

In order to achieve the above-mentioned object, the present invention comprises a cooling device as described below.

That is, in the cooling system for a four-stroke engine according to the first aspect, an oil reservoir provided near the crankcase is configured as an oil reservoir partitioned from the crankcase. The opening is located above the oil level of the oil stored in the oil reservoir, and the first air is introduced from outside to the oil reservoir when the oil reservoir has a negative pressure. Air introducing means and, similarly, the opening is configured to be higher than the oil level of the oil chamber regardless of the inclined state, and the direction from the oil chamber to the crank chamber when the crank chamber becomes negative pressure A second air introducing means for sending air to the oil supply chamber, and a mixing means provided in the middle of a supply route of the oil from the oil reservoir to the crank chamber and mixing the air and the oil from the second air introducing means. ing.

[0007] According to the cooling device having such a configuration, regardless of the inclined state, outside air having a low temperature is introduced into the oil reservoir through the first air introducing means, and the second air is cooled by the cooling blower from the oil reservoir. By guiding the crankcase through the air introducing means and the mixing means to the crankcase, the inside of the crankcase can be cooled.

[0008] In the cooling apparatus for a four-cycle engine according to the second aspect, the first air introducing means and the second air introducing means according to the first aspect are arranged such that the first air introducing means and the second air introducing means have a substantially central position in a three-dimensional space inside the oil reservoir. It is constituted by opening.

According to this configuration, the opening is disposed above the oil level of the oil stored in the oil reservoir with a simple configuration, regardless of the inclination of the oil reservoir.

In the cooling apparatus for a four-stroke engine according to the third aspect, the first air introducing means and the second air introducing means may have a flexible tubular body, a floating opening in oil, and an oil level. And a float that is supported above.

According to the cooling device having such a configuration, the opening is disposed above the oil level of the oil regardless of the amount of the stored oil, regardless of the inclination of the oil reservoir.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a front sectional view of a four-stroke engine provided with the cooling device of the present invention, and FIGS. 2 and 6 are sectional views taken along lines AA and BB of FIG. 1, respectively.

The four-stroke engine E shown in FIG. 1 has an air cleaner 2 and a carburetor 4 on the left side and an exhaust muffler 6 on the right side, and has a cylinder block 10 provided with a cylinder head 10 at the top. 12 and a crankcase 14, and further has an oil reservoir 18 provided on the side of the crankcase 14. This oil reservoir 18
Has a characteristic configuration of the present invention, and is formed as a separate case from the crankcase 14, and the crankcase 1
6 and a closed space as a whole.

As shown in FIGS. 1 and 2, the oil reservoir 18 has a first air introduction pipe 2 serving as first air introduction means.
0, a second air introduction pipe 22 as a second air introduction means and an oil suction section 60 are provided. First air introduction pipe 20
The second air introduction pipe 22 is opened at a substantially central position in the three-dimensional space in the oil reservoir 18 as shown in FIG. 1, so that the amount of oil stored in the oil reservoir 18 does not exceed a required amount. Within this range, the oil reservoir 18 has a configuration in which oil does not leak outside through the first air introduction pipe 20 or the second air introduction pipe 22 in any inclined state.

The first air introduction pipe 20 is opened in the air cleaner 2 and has one end provided therein, and the other end disposed at the predetermined position in the oil reservoir 18. One end of the second air introduction pipe 22 is arranged to be open at the above-mentioned predetermined position in the oil reservoir 18, and the other end extends below the crank chamber 16 from the oil reservoir 18.

The oil suction section 60 shown in FIG. 1 or FIG.
Is formed of a tube 62 of a predetermined length which is easily bent using an elastic material such as a rubber material, and a weight 64 is provided at the tip thereof. That is, the weight 64 always bends vertically downward. As a result, the tip of the oil suction section 60 always exists below the oil level of the oil that has accumulated in an appropriate amount regardless of the inclination of the oil reservoir 18. The material of the tube 62 and the weight 64 of the oil suction section 60 is preferably one having oil resistance and heat resistance. The other end of the tube 62 of the oil suction section 60 is connected to a lower end of an oil mixer 72 described later.

Cylinder block 12 and crankcase 1
4 supports a crankshaft 28 whose axis is provided in the horizontal direction via bearings 24 and 26 as shown in FIG. The bearings 24 and 26 are so-called open type ball bearings without a shield, and as shown in FIG. 3, oil or oil mist can pass through a gap 26b provided between the balls 26a.

As shown in FIG. 1, a piston 30 connected to a crank pin 28b of a crank shaft 28 via a connecting rod 29 is slidably fitted to a cylinder 12a provided inside the cylinder block 12. I have.

Also, as shown in FIG.
8 has a recoil starter 30 at the right end thereof and a cooling blower 32 coaxially fitted at the left end thereof. For the purpose of blowing heat to take heat, the cooling blower 32 performs a rotating motion by the rotation of the crankshaft 28, and
2 and a function of sending outside air to the crankcase 14, the oil reservoir 18 and a mixing section case 74 described later.

An intake port 34 and an exhaust port 36 are respectively formed on the top wall of the cylinder 12a and connected to the carburetor 4 and the exhaust muffler 6, and an intake valve 35 and an exhaust valve 37 for opening and closing these ports are inserted. Have been. The valve drive unit 40 for driving these valves is constituted by components such as a crank side sprocket 42, a chain 44, a cam side sprocket 46, a cam shaft 48, and the like. Each component of the valve drive unit 40 is provided on a side of the cylinder block 12 and the crankcase 14 such that the valve operating chamber 50 formed in the cylinder head 10 and the valve operating chamber 50 communicate with the crank chamber 16. It is arranged in the formed communication path 52.

Between the oil reservoir 18 and the crankcase 16,
A mixing means 70 having an oil mixer 72, a mixer chamber 76 and a ball type check valve 78 is provided.

As shown in FIG. 1, the oil mixer 72 has a substantially cylindrical shape that is vertically erected in the vertical direction, and has an oil mist passage 72a communicating from the oil suction portion 60 to the crank chamber 16. And a mixer chamber 76 described later.
Air passage 72b that communicates with oil mist passage 72a
It has. The periphery of the oil mixer 72 is the crankcase 1
A mixer chamber 76 partitioned by the lower surface 6 and the mixing section case 74 is provided, and one end of the second air introduction pipe 22 communicating with the oil reservoir 18 is connected to a side portion of the mixing section case 74. I have.

The diameter of the air passage 72b is about 1/2 to the diameter of the oil mist passage 72a provided substantially vertically.
Twelve air passages 72b each having a diameter of 1/3 are provided in a substantially horizontal direction. As described above, when the air passage 72b is constituted by one or a plurality of passages having a smaller diameter than the oil mist passage 72a, the oil mist passage 7
When oil having a predetermined flow rate flows through 2a, the effect of sucking air from air passage 72b into oil mist passage 72a is efficiently exhibited, and sufficient air is introduced into oil mist through air passage 72b. .

On the upper part of the oil mixer 72, as a means for opening and closing the oil mist passage 72a, a check ball 78a, a spring 78b, and a spring holder 7 shown in FIG.
A ball-type check valve 78 having 8c is provided. Spring retainer 78c and check ball 78a
Spring 78b urges the check ball 78a downward, and the urged check ball 78
a is a tapered surface 72c provided above the oil mixer 72
When the crank chamber 16 is at a positive pressure, the oil mist passage 72a is closed. Spring 78b
When the crank chamber 16 has a negative pressure for a predetermined amount,
It is determined in advance that the check ball 78a is sucked toward the crank chamber 16 and rises to open the oil mist passage 72a.

As shown in FIG. 5 which is a plan view of the spring retainer 78c, the spring retainer 78c has four or a plurality of retaining claws 78d. The space where the retaining claws 78d are not provided is separated from the oil mixer 72 by the crank chamber. It communicates with 16. In this embodiment, the spring retainer 78c having the retainer pawl 78d is provided separately from the crankcase 14, but may be formed integrally.

The oil sent to the valve operating chamber 50 through the crank chamber 16 by the mixing means 70 having the above structure is returned to the oil storage chamber 18, so that the valve operating chamber 5 as shown in FIG.
An oil return pipe 80 is connected to the side of the cylinder block 12 and the crankcase 14 and has one end connected to one side of the cylinder block 12 and the other end connected to the oil reservoir 18.

A hole 82a formed in the bottom of the crank chamber 16 and a groove formed on the upper surface of the mixing case 74 shown in FIG. 82b and a pipe 82c provided on the side surface of the mixing section case 74.
Is provided. The pipe 82 of the oil return passage 82
c is connected in communication at an intermediate position of the oil return pipe 80.

The operation of the present embodiment configured as described above is as follows. FIG. 1 shows a use state in a so-called upright position in which the valve operating chamber 50 of the engine main body is not inclined upward with the posture of the hand-held working machine on which the four-cycle engine E is mounted. At this time, an appropriate amount of lubricating oil is stored in the crank chamber 16, the oil storage chamber 18, and the valve operating chamber 50. The tip of the oil suction section 60 of the oil reservoir 18 is submerged in oil.

When the four-cycle engine E is operated, a pressure change occurs in the crank chamber 16 due to the vertical movement of the piston 30. That is, in the upward stroke of the piston 30, the pressure in the crank chamber 16 is reduced to a negative pressure state, and in the downward stroke, the pressure in the crank chamber 16 is increased to a positive pressure state.

The four-cycle engine E generates heat by its operation. In response to the generated heat, heat is radiated from the surfaces of the cylinder block 12, the crankcase 14, etc., and the cylinder block 12, the crankcase 14 The active cooling of the oil reservoir 18 and the mixing section case 74 is performed.

When the pressure in the crank chamber 16 becomes negative, the check ball 78a of the ball type check valve 78 overcomes the urging force of the spring 78b and moves up from the tapered surface 72c of the oil mixer 72. As a result, the oil mist passage 72 a provided in the oil mixer 72 is opened, and the oil pressure in the oil sump 1 is determined based on the pressure difference between the crank chamber 16 and the oil sump 18.
The oil stored in 8 is sucked from the tip of the oil suction section 60 and flows into the oil mist passage 72a at a predetermined flow rate.

When the oil flows into the oil mist passage 72a, an oil flow having a predetermined flow velocity causes an effect of sucking air from the air passage into the oil mist passage 72a, and the air stored in the mixer chamber 76 is removed from the air. It is sucked into the oil mist passage 72a through the passage 72b. This suction action makes the mixer chamber 76 a negative pressure, and newly guides the air in the oil reservoir 18 whose temperature has dropped from the second air introduction pipe 22 to the mixer chamber 76 to cool the mixer chamber 76.

The pressure of the oil reservoir 18 is reduced as compared with the atmospheric pressure by sending air to the mixer chamber 76, so that air is introduced from the air cleaner 2 through the first air introduction pipe 20. At this time, the oil reservoir 18 whose temperature has risen due to heat propagation from the engine or the like is cooled by introducing fresh air having a low temperature from the air cleaner 2 side in addition to the cooling action by the cooling blower 32.

In the oil mist passage 72a, the oil sucked from the oil reservoir 18 and the air sucked from the mixer chamber 76 are mixed to form an oil mist. Spreads in. The oil mist in which low-temperature air and oil are mixed reduces the temperature inside the engine by being introduced into the crankcase 16.

The oil mist is continuously formed as long as the inside of the crank chamber 16 is kept at a predetermined negative pressure. The oil mist is formed through an oil return passage 82 provided from the bottom of the crank chamber 16 to the oil return pipe 80. When the pressure in the crank chamber 16 is increased, oil or oil mist is returned toward the oil reservoir 18, so that the oil is not excessively stored in the crank chamber 16. Accordingly, it is possible to supply an appropriate amount of oil (oil mist) to the valve operating chamber 50 while preventing excessive accumulation of oil in the crank chamber 16, and to prevent power loss due to excessive supply.

Subsequently, the piston 30 enters the descending stroke,
The pressure in the crank chamber 16 becomes positive. When the pressure in the crank chamber 16 becomes positive, the check ball 78a of the ball type check valve 78 is brought into contact with the tapered surface 72c of the oil mixer 72 by this pressure and the urging force of the spring 78b. Therefore, the oil mist passage 72 of the oil mixer 72
a is closed, and the introduction of oil mist from the oil reservoir 18 to the crank chamber 16 is stopped.

The oil mist introduced into the crank chamber 16 is supplied to the bearing 26 together with the pressurized air.
Is sent to the communication path 52 through the gap 26b.

The oil mist sent to the communication passage 52 is sent to the valve operating chamber 50 by positive pressure, and the oil mist is sent to the valve driving section 40.
Lubricate each part. Camshaft 48, intake valve 3
5. The lubricated oil or oil mist sent to the position of the exhaust valve 37 and the like is returned to the oil reservoir 18 through an oil return pipe 80 provided on the side of the valve operating chamber 50. On the other hand, surplus air in the valve train 50 is supplied to a breather pipe (not shown).
Through the air cleaner 2.

Next, the attitude of the four-cycle engine E is changed during operation, and the valve operating chamber 50 of the engine body is used in the inverted position as shown in FIG. As described above, even when the air cleaner 2 and the exhaust muffler 6 are used at an inclined position facing up and down,
The lubricating oil or oil mist lubricates the inside of the four-stroke engine E in the same manner as in the above-mentioned upright position.
At this time, the first air introduction pipe 20 arranged in the oil reservoir 18
The opening of the second air introduction pipe 22 is always located above the oil level without being immersed in the oil stored in a predetermined amount.

Further, as shown in FIG. 9, even when the crankshaft 28 of the engine body is used at an inclined position facing up and down, the openings of the first air introduction pipe 20 and the second air introduction pipe 22 are It is above the oil level and does not sink into the oil.

As can be determined from these figures, the air in the low-temperature oil reservoir 18 is introduced into the high-temperature crank chamber 16 regardless of the inclination state of the four-cycle engine E, and the engine is reliably driven. Internal cooling is performed.

In the second embodiment, as shown in FIG. 10, the first air introduction pipe 20 and the second air introduction pipe 22 are used.
Is composed of a flexible pipe, and has a specific gravity lower than that of the oil, and floats on the oil, and the openings of the first air introduction pipe 20 and the second air introduction pipe 22 are stored in the oil reservoir 18. And a float 90 supported above the oil level.

The float 90 may support the first air introduction pipe 20 and the second air introduction pipe 22 as a single body as shown in the drawing, or may be provided one for each air introduction pipe.

In the second embodiment constructed as described above, even if the attitude is changed during operation of the four-cycle engine E to increase the inclination, the float 90 is always in the oil state regardless of the amount of the stored oil. The first air introduction pipe 20 and the second air introduction pipe 22 are positioned above the oil level without being immersed in oil.

Therefore, as in the first embodiment, the air in the low temperature oil sump chamber 18 is introduced into the crank chamber 16 regardless of the inclination state of the four-cycle engine E, and the engine is reliably driven. Internal cooling is provided.

It should be noted that the present invention is not limited to the configuration of each of the above embodiments, and various modifications can be made within the scope of the invention. For example, the first air introduction pipe 20 and the second
The air introduction pipe 22 may be formed as a continuous and integral air introduction pipe, and have an opening through which air can enter and exit at a substantially central position in the three-dimensional space of the oil reservoir 18.
Further, although the cooling device according to the present invention is used in an OHC type four-cycle engine in the figure, it may be used in an OHV type four-cycle engine or the like.

[0047]

As described above, according to the present invention, 4
According to the cooling device for a cycle engine, an excellent effect is provided in that the engine is reliably cooled internally regardless of the inclination angle.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a four-cycle engine including a cooling device according to the present embodiment.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a schematic configuration diagram of a bearing of a four-cycle engine including the cooling device according to the present embodiment.

FIG. 4 is a schematic configuration diagram of a ball-type check valve of the cooling device according to the present embodiment.

FIG. 5 is a plan view of a spring press in the ball-type check valve of the cooling device according to the present embodiment.

FIG. 6 is a sectional view taken along line BB of FIG. 1;

FIG. 7 is an explanatory diagram of lubrication in an inclined state in which a valve train of a four-cycle engine is directed downward.

FIG. 8 is an explanatory diagram of lubrication in an inclined state in which an air cleaner and an exhaust muffler of a four-cycle engine are directed vertically.

FIG. 9 is an explanatory diagram of lubrication in a tilted state in which a drive shaft and a crankshaft of a four-cycle engine are directed vertically.

FIG. 10 is a schematic configuration diagram of a first air introduction pipe and a second air introduction pipe of a cooling device according to a second embodiment.

[Explanation of symbols]

 E 4 cycle engine 12 cylinder block 14 crankcase 16 crankcase 18 oil reservoir 20 first air introduction pipe 22 second air introduction pipe 32 cooling blower 70 mixing means 90 float

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mitsunori Watanabe 35-Ooka, Numazu-shi, Shizuoka Prefecture Inside Fuji Robin Co., Ltd. (72) Kenji Imafuku 2-10-5 Shinmeidai, Hamura-shi, Tokyo Inside the Technical Research Institute

Claims (3)

[Claims] Cylinder block by cooling blower,
In a cooling device for a four-stroke engine provided in the vicinity of a crankcase and a crankcase for cooling an oil sump for storing oil to be supplied to the crankcase, the oil sump is configured as an oil sump partitioned from the crankcase. An opening is always provided above the oil level of the oil reservoir, regardless of the inclination state of the oil reservoir, and the oil reservoir is externally provided when the oil reservoir has a negative pressure. A first air introducing means for introducing air into the oil reservoir; an opening is always provided above an oil level of the oil reservoir, regardless of an inclined state of the oil reservoir; A second air introducing means for sending air from the oil reservoir to the crank chamber when the oil is supplied; and a second air introducing means provided in a supply route of the oil from the oil reservoir to the crank chamber. Air of oil A cooling device for a four-stroke engine, comprising: 2. The apparatus according to claim 1, wherein the first air introduction unit and the second air introduction unit are configured to open at a substantially central position in a three-dimensional space in the oil reservoir. Cooling system for 4-cycle engine. 3. The first air introduction unit and the second air introduction unit each include: a flexible tube; and a float that floats on oil and supports the opening above an oil level. The cooling device for a four-stroke engine according to claim 1, wherein: