JPH06146837A - Lubricating device for four cycle engine - Google Patents

Abstract

PURPOSE:To use a portable working device on which a four cycle engine is mounted at all positions by providing the four cycle engine for lubricating each part in a crank chamber by means lubricating oil which is included in mixture air, thus requiring no more oil pan. CONSTITUTION:In a four cycle engine having a crank chamber 4 and in which pressure is changed in association with reciprocating motion of a piston 3, a communicating passage 21 is provided to communicate an intake passage 20 for supplying mixture air which includes lubricating oil with the crank chamber 4, and a valve 22 is provided in the communicating passage 21 so as to close it at the time of nearly explosion stroke and nearly compression stroke while opening it at the time of nearly intake stroke and nearly compression stroke, or to close it at the time of nearly compression stroke and nearly explosion stroke while opening it at the time of nearly exhaust stroke and nearly intake stroke.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubrication device for a four-cycle engine in which each part in a crank chamber is lubricated by a lubricating oil contained in an air-fuel mixture.

[0002]

2. Description of the Related Art Since a portable working machine such as a mower is operated in an all-position tilted in various directions, such a portable working machine uses a mixed fuel in which fuel and lubricating oil are mixed. In general, it is equipped with a two-cycle engine. However, in recent years, mounting of a 4-cycle engine on such a portable working machine has been considered because of the necessity of exhaust gas purification. Here, as a 4-cycle engine to be mounted on a portable work machine, there is one disclosed in Japanese Utility Model Laid-Open No. 4-93707, and by devising the shape of the oil pan, the portable work machine has a fixed range. Even if it is tilted inside, the oil does not leak out.

[0003]

[Problems to be Solved by the Invention]
In the portable working machine equipped with the four-cycle engine disclosed in Japanese Patent No. 3707, when the portable working machine is tilted so that the four-cycle engine is substantially inverted, the oil leaks from the oil pan. Occurs,
This portable work machine cannot be used in all positions. Also, maintenance such as oil supply, inspection, and replacement is required, which is troublesome. Further, it is difficult to reduce the size and weight of the 4-cycle engine by providing the oil pan.

[0004]

The invention according to claim 1 is
In a four-cycle engine having a crank chamber whose pressure changes with the reciprocating movement of a piston, an intake passage for supplying an air-fuel mixture containing lubricating oil into a cylinder and a communication passage for communicating the crank chamber are provided, and a substantially suction The valve is opened during the stroke and the approximate compression stroke and is closed during the approximate explosion stroke and the approximate exhaust stroke, or is opened during the approximate exhaust stroke and the approximate intake stroke and approximate compression stroke. A valve that is closed between the time and the time of approximately the explosion stroke is provided in the communication passage.

According to a second aspect of the present invention, in the first aspect of the invention, one of an intake cam that opens and closes the intake valve and an exhaust cam that opens and closes the exhaust valve is an opening and closing drive section that drives the valve to open and close.

According to a third aspect of the present invention, in the first or second aspect of the invention, the communication passage is communicated with a substantially bottom portion of the crank chamber.

According to a fourth aspect of the present invention, in the first, second or third aspect of the invention, the valve mechanism storage space in which the valve mechanism is accommodated is part of the communication passage.

[0008]

According to the invention described in claim 1, the valve is opened during the compression stroke or the exhaust stroke when the pressure in the crank chamber is reduced, so that the air-fuel mixture containing the lubricating oil is distributed between the intake passage and the communication passage. Flow into the crank chamber. In addition, the valve opens during the intake stroke when the pressure in the crank chamber rises, so that the air-fuel mixture in the crank chamber is sent back to the intake passage side in a state of flowing backward in the communication passage, and this air-fuel mixture passes through the intake passage. Is sucked into the cylinder. Therefore, since the air-fuel mixture containing the lubricating oil enters and leaves the crank chamber, the lubricating oil lubricates the respective parts in the crank chamber. During the explosion stroke, even if the pressure in the crank chamber rises because the valve is closed, the air-fuel mixture is sent out from the crank chamber and the sent air-fuel mixture flows back toward the carburetor. There is no "blowback" that goes out of the engine.

According to the second aspect of the invention, the opening / closing control of the valve is performed by either the intake cam or the exhaust cam, and a dedicated component for controlling the opening / closing of the valve is not required.

According to the third aspect of the present invention, even when the lubricating oil is separated from the air-fuel mixture in the crank chamber,
Since the separated lubricating oil is sent out together with the air-fuel mixture in the crank chamber when it is sent back to the intake passage side while flowing backward in the communication passage, a large amount of lubricating oil does not accumulate at the bottom of the crank chamber.

According to the fourth aspect of the present invention, the lubricating oil contained in the air-fuel mixture lubricates not only each part in the crank chamber but also the valve operating mechanism in the valve operating mechanism housing space.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the invention according to claim 1 or 3 is shown in FIG.
And it demonstrates based on FIG. First, FIG. 1 shows the overall structure of a four-cycle engine mounted and used in a portable work machine or the like. A cylinder 2 is formed in an upper part of a crankcase 1, and a piston 3 is formed in the cylinder 2. It is stored so that it can slide back and forth. A crank chamber 4 is formed in the crank case 1, and a crank shaft 5 and a cam shaft 6 are rotatably provided in the crank chamber 4. Further, a cylinder head 7 is attached to the upper portion of the cylinder 2, and an intake port 9 opened and closed by an intake valve 8 and an exhaust port 11 opened and closed by an exhaust valve 10 are formed in the cylinder head 7. The piston 3 is connected to the crankshaft 5 via a connecting rod 12, and a crank gear 13 fixed to one end of the crankshaft 5 and a cam gear 14 fixed to one end of the camshaft 6. Mesh with each other, and the number of teeth of the cam gear 14 is set to be twice the number of teeth of the crank gear 13.

An intake cam 15 and an exhaust cam 16 are fixed to the camshaft 6, and a slidable tappet 17 is brought into contact with the intake cam 15, and the tappet 17 is attached thereto.
The push rod 18 is in contact with one end of the push rod 18, and the other end of the push rod 18 is in contact with one end of a rocker arm (not shown) that drives the intake valve 10 to open and close.
A tappet (not shown) is also brought into contact with the exhaust cam 16, and the other end of a push rod (not shown) whose one end is brought into contact with the tappet is the rocker that drives the exhaust valve 10 to open and close. It is in contact with one end of an arm (not shown).

Next, there is provided a carburetor 19 which mixes liquid fuel mixed with lubricating oil and air to form an air-fuel mixture. The carburetor 19 and the intake port 9 are connected to the intake passage 2
It is connected by 0. A communication passage 21 that communicates the intake passage 20 with the bottom of the crank chamber 4 is provided. In the middle of the communication passage 21, a valve is opened during an intake stroke and a compression stroke and an explosion occurs. A valve 22 is provided that is closed during the stroke and the exhaust stroke. In addition,
The valve 22 is provided so as to be slidable in a direction in which it comes into contact with and separates from the cam shaft 6, and further urges the valve 22 in a direction in which it comes into contact with a dedicated cam 23 fixed to the cam shaft 6. A spring 24 is provided.

With such a structure, the opening / closing timings of the intake valve 8, the exhaust valve 10, and the valve 22 in each stroke of the intake, compression, explosion, and exhaust of the 4-cycle engine will be described with reference to the timing chart of FIG. . The valves 8, 10, and 22 are opened and closed accurately at the timings associated with the rotation of the camshaft 6.

First, during the compression stroke, the piston 3 rises with the intake valve 8 and the exhaust valve 10 closed, and the air-fuel mixture sucked into the cylinder 2 during the previous suction stroke is compressed. . On the other hand, since the valve 22 pushed downward by the dedicated cam 23 is opened and the inside of the crank chamber 4 becomes a negative pressure state as the piston 3 rises, a mixture is formed in the carburetor 19. This air-fuel mixture is drawn into the crank chamber 4 through the intake passage 20 and the communication passage 21.

During the explosion stroke, the intake valve 8 and the exhaust valve 10 are maintained in the closed state, the air-fuel mixture in the cylinder 2 explodes, and the piston 3 descends. In addition,
The valve 22 is closed, and the air-fuel mixture in the crank chamber 4 is compressed as the piston 3 descends.
Stays in the crank chamber 4 without being sent out from.

During the exhaust stroke, the piston 3 rises with the exhaust valve 10 opened and the intake valve 8 closed, and the combustion gas in the cylinder 2 is exhausted from the exhaust port 11. On the other hand, the air-fuel mixture in the crank chamber 4 expands as the piston 3 rises, but since the valve 22 is kept closed, new air-fuel mixture flows into the crank chamber 4 and the crank chamber 4 is closed. Sending of air-fuel mixture from does not occur.

During the intake stroke, the piston 3 descends with the intake valve 8 open and the exhaust valve 10 closed as shown in FIG.
Is opened. Therefore, as the piston 3 descends, the air-fuel mixture in the crank chamber 4 is sent out to the intake passage 20 side while flowing backward in the communication passage 21, and the air-fuel mixture is discharged.
It is sucked into the cylinder 2 through 0 and the intake port 9. If the air-fuel mixture sent from the crank chamber 4 alone is insufficient for the air-fuel mixture sucked into the cylinder 2, the shortage is formed by the carburetor 19 and the intake passage 20 and the intake port 9 are formed. It is sucked into the cylinder 2 through the inside.

As described above, since the air-fuel mixture containing the lubricating oil flows in and out of the crank chamber 4 as the four-cycle engine operates, each part in the crank chamber 4 is lubricated by the lubricating oil contained in the air-fuel mixture. It Therefore, an oil pan for storing lubricating oil is not required, and the 4-cycle engine can be made smaller and lighter. Further, even when the 4-cycle engine is tilted so as to be substantially inverted, the leakage of the lubricating oil does not occur.
A portable work machine equipped with a cycle engine can be used in all positions.

Further, since the communication passage 21 communicates with the bottom of the crank chamber 4, the lubricating oil separated from the air-fuel mixture in the crank chamber 4 sucks the lubricating oil in the crank chamber 4 through the communication passage 21. It is sent out together when it is sent to the passage 20 side. Therefore, a large amount of lubricating oil does not accumulate at the bottom of the crank chamber 4 and the lubricating oil does not resist the rotation of the crankshaft 5.

In this embodiment, regarding the opening / closing timing of the valve 22, the valve is opened during the intake stroke and the compression stroke and closed during the explosion stroke and the exhaust stroke. However, the valve may be opened during the exhaust stroke and the intake stroke and closed during the compression stroke and the explosion stroke, as indicated by the broken line in FIG. Further, such a change in the opening / closing timing of the valve 22 is performed by changing the axial center of the tappet 17 and the valve 22.
Change the relative angle "θ ₁ " with the axis of the
This can be done by changing the relative angle “θ ₂ ” of 5 and the dedicated cam 23.

Further, in the present embodiment, the formation of the air-fuel mixture containing the lubricating oil has been described by exemplifying the case where the liquid fuel mixed with the lubricating oil is mixed with the air. In 19, the mixture of fuel and air is formed to form a mixture containing no lubricating oil, and the mixture is supplied from the oil pump in a spray form to the mixture containing the lubricating oil. You may form.

Next, an embodiment of the invention described in claim 2 will be described with reference to FIGS. 3 and 4. 1 and 2
The same parts as those described in 1 are indicated by the same reference numerals, and description thereof will be omitted (the same applies hereinafter). In this embodiment, the valve 22
The exhaust cam 1 is provided at a position facing the exhaust cam 16.
6 is an opening / closing drive unit for driving the valve 22 to open / close.

In such a structure, the opening / closing drive of the valve 22 is performed by the exhaust cam 16, so that the valve opening period of the valve 22 is shortened as shown in FIG. 4, but the lubrication in the crank chamber 4 is performed as shown in FIG. And the same as in the case of the 4-cycle engine shown in FIG. In the present embodiment, the valve opening timing of the valve 22 can be changed by changing the relative angle “θ ₁ ” of the axis of the tappet 17 and the axis of the valve 22. Further, in this embodiment,
Since the exhaust cam 16 is used as the opening / closing drive unit that drives the valve 22 to open / close, a dedicated member for driving the valve 22 to open / close is not required, and the cost is reduced.

Next, an embodiment of the invention described in claim 4 will be described with reference to FIG. Above the cylinder head 7, a valve operating mechanism storage space 2 surrounded by a rocker cover 25.
6 is formed, and the spring 2 that biases the intake valve 8 in the valve closing direction is formed in the valve mechanism storage space 26.
7. A spring (not shown) for urging the exhaust valve 10 in the valve closing direction and a valve mechanism 29 including a rocker arm 28 for urging the intake valve 8 and the exhaust valve 10 in the valve opening direction are housed. There is. The rocker arm 28
Is swingably attached to the upper portion of the cylinder head 7 by an adjusting screw (not shown), and one end of the rocker arm 28 is brought into contact with the upper end portions of the intake valve 8 and the exhaust valve 10, so that the rocker arm 28 The other end of the push rod 18 is in contact with the other end of the.

Next, the intake passage 20 and the valve operating mechanism housing space 26 are communicated with each other by a communication hole 30, and the valve operating mechanism housing space 26 and the crank chamber 4 are communicated with each other by a passage 31. Then, the communication passage 3 that connects the intake passage 20 and the bottom of the crank chamber 4 by the communication hole 30, the valve mechanism storage space 26, and the passage 31.
2 is formed, and the valve mechanism storage space 26 is a part of the communication passage 32.

In such a structure, during the compression stroke in which the piston 3 rises and the valve 22 is opened, the lubricating oil containing the air-fuel mixture is introduced from the intake passage 20 into the communication passage 3.
Lubricating oil contained in the air-fuel mixture is sucked into the crank chamber 4 through 2 to lubricate each part in the crank chamber 4. Further, since this air-fuel mixture passes through the inside of the valve mechanism storage space 26 which is a part of the communication passage 32, the valve mechanism 29 is also lubricated by the lubricating oil contained in the air-fuel mixture.

On the other hand, the air-fuel mixture sucked into the crank chamber 4 flows from the crank chamber 4 into the communication passage 32 during the intake stroke in which the intake valve 8 and the valve 22 are opened and the piston 3 is lowered. Is sent to the intake passage 20 side and is sucked into the cylinder 2.

[0030]

As described above, in the four-cycle engine having the crank chamber in which the pressure changes with the reciprocating movement of the piston, the air-fuel mixture containing the lubricating oil is supplied into the cylinder. A communication passage that connects the intake passage and the crank chamber is provided, and the valve is opened during the intake stroke and the compression stroke, and is closed during the explosion stroke and the exhaust stroke, or is exhausted. Since a valve that is opened during the stroke and during the intake stroke and closed during the compression stroke and the explosion stroke is provided in the communication passage, the pressure in the crank chamber decreases during the compression stroke. Alternatively, by opening the valve during the exhaust stroke, the air-fuel mixture containing lubricating oil flows into the crank chamber through the intake passage and the communication passage, and
When the valve is opened during the intake stroke when the pressure in the crank chamber rises, the air-fuel mixture in the crank chamber is sent out to the intake passage side in the state of flowing backward in the communication passage and is sucked into the cylinder. Along with this, the air-fuel mixture containing the lubricating oil goes in and out of the crank chamber, and it is possible to lubricate each part in the crank chamber with this lubricating oil. Therefore, an oil pan for storing the oil for lubrication is not necessary. It is possible to reduce the size and weight of the 4-cycle engine, and to use a portable work machine equipped with this 4-cycle engine in all positions. Furthermore, it is troublesome to change oil for lubrication. It has an effect that it can be omitted.

As described above, the invention according to claim 2 is, in the invention according to claim 1, an opening / closing drive for opening and closing either one of an intake cam for opening and closing an intake valve and an exhaust cam for opening and closing an exhaust valve. Since this is a part, there is an effect that a dedicated part for driving the valve to be opened and closed is not required and the cost can be reduced.

According to the third aspect of the invention, as described above, in the first or second aspect of the invention, the communication passage is communicated with the substantially bottom portion of the crank chamber, so that the lubricating oil is separated from the air-fuel mixture in the crank chamber. Even if it occurs, this lubricating oil can be sent out to the intake passage side together with the air-fuel mixture, so that a large amount of lubricating oil accumulates at the bottom of the crank chamber and this lubricating oil becomes a resistance to the rotation of the crankshaft. It has the effect of preventing the occurrence of situations.

As described above, according to the invention of claim 4, in the invention of claim 1, 2 or 3, since the valve mechanism storage space for accommodating the valve mechanism is part of the communication passage, With the lubricating oil contained in, it is possible to lubricate not only each part in the crank chamber but also the valve train.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing an embodiment of the invention according to claim 1 or 3. FIG.

FIG. 2 is a timing chart showing the opening / closing timing of each valve.

FIG. 3 is a vertical sectional front view showing an embodiment of the invention as set forth in claim 2;

FIG. 4 is a timing chart showing the opening / closing timing of each valve.

FIG. 5 is a vertical sectional front view showing an embodiment of the invention as set forth in claim 4;

[Explanation of symbols]

 2 cylinder 3 piston 4 crank chamber 8 intake valve 10 exhaust valve 15 intake cam 16 exhaust cam 20 intake passage 21, 32 communication passage 26 valve mechanism storage space 29 valve mechanism

Claims (4)

[Claims] 1. A four-cycle engine having a crank chamber whose pressure changes in accordance with the reciprocating movement of a piston, and a communication passage for communicating an intake passage for supplying a mixture containing lubricating oil into a cylinder and the crank chamber. The valve is opened during the intake stroke and the compression stroke, and is closed during the explosion stroke and the exhaust stroke, or is opened during the exhaust stroke and the intake stroke. A lubricating system for a four-cycle engine, characterized in that a valve that is closed during a substantially compression stroke and a substantially explosion stroke is provided in the communication passage. 2. The lubrication for a four-cycle engine according to claim 1, wherein one of an intake cam that opens and closes the intake valve and an exhaust cam that opens and closes the exhaust valve is an opening and closing drive unit that drives the valve to open and close. apparatus. 3. The lubrication device for a four-cycle engine according to claim 1, wherein the communication passage is communicated with a substantially bottom portion of the crank chamber. 4. The lubrication device for a four-cycle engine according to claim 1, 2 or 3, wherein a valve mechanism storage space for accommodating the valve mechanism is part of a communication passage.