JPH0734838A - Lubricating device of four-cycle engine - Google Patents

Abstract

PURPOSE:To prevent the generation of the wear and seizure of a bearing part especially caused by the defective lubrication by feeding the mixture containing the lubricating oil into the cylinder through a crank chamber, and lubricating the bearing part of a cam shaft stored in the crank chamber and various parts in the crank chamber. CONSTITUTION:An intake passage where the mixed air containing the lubricating oil to be formed in a mixture forming part is fed to a crank chamber 5 is provided, and a mixture passage 30 where the mixture in the crank chamber 5 is fed into the cylinder is provided. A passage 39 which is located in the crank chamber 5 and passes the mixture to bearing parts 9, 10 to pivotably support the end of a cam shaft 11 is formed, passages 36, 38 are formed between the bearing parts 9, 10 and the inner circumferential surface of the crank chamber 5 are formed, and these passages 36, 38 are communicated with the mixture passage 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION According to the present invention, the crank chamber is lubricated by the lubricating oil contained in the air-fuel mixture.
The present invention relates to a lubrication device for a cycle engine.

[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 lubricating oil stored in the oil pan is prevented from leaking 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 lubricating oil leaks from the oil pan. Because the outflow occurs,
This portable work machine cannot be used in all positions.

Further, the oil pan is a heavy object, and moreover, a large amount of lubricating oil is stored in the oil pan, and further, the weight increase due to the valve operating system parts is added.
Compared to a two-cycle engine with the same displacement, the weight is significantly increased, and the labor of the operator is increasing.

Further, maintenance such as replenishment, inspection, and replacement of lubricating oil is required, which is complicated in handling.

[0006]

The invention according to claim 1 is
In a four-cycle engine having a crank chamber in which a crankshaft and a camshaft with a fixed cam gear are fixed and whose internal pressure fluctuates with the reciprocating movement of a piston, a mixture containing lubricating oil formed in a mixture forming section An intake passage for supplying air to the crank chamber is provided, an air-fuel mixture passage is provided for communicating the crank chamber with the inside of the cylinder, and is mixed with a bearing portion located in the crank chamber and axially supporting the end portion of the camshaft. A passage hole through which air passes is formed, a passage is formed between the bearing portion and the inner peripheral surface of the crank chamber, and the passage is communicated with the mixture passage.

According to a second aspect of the present invention, in the first aspect of the invention, a passage hole through which the air-fuel mixture passes is formed in the cam gear.

[0008]

According to the first aspect of the present invention, the air-fuel mixture containing the lubricating oil formed in the air-fuel mixture forming portion is supplied to the crank chamber through the intake passage, and the air-fuel mixture is reciprocally moved by the piston. It is supplied into the cylinder via the air-fuel mixture passage according to the pressure fluctuation in the chamber. Therefore, the crank chamber is lubricated by the lubricating oil contained in the air-fuel mixture, and an oil pan or the like for lubricating the crank chamber is not required. Further, when the lubricating oil in the crank chamber flows into the air-fuel mixture passage, at least a part of the air-fuel mixture passes through the passage hole of the bearing portion and reaches the passage, and then flows into the air-fuel mixture passage through this passage. Therefore, the bearing portion of the camshaft is satisfactorily lubricated.

According to the second aspect of the present invention, when the lubricating oil in the crank chamber flows into the air-fuel mixture passage, at least a part of the air-fuel mixture passes through the passage hole of the cam gear and the passage hole of the bearing portion and the passage. Since it reaches the inside and flows into the air-fuel mixture passage through this passage, the bearing portion hidden behind the cam gear is satisfactorily lubricated.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. First, FIG. 2 is a vertical sectional front view showing the overall structure of a four-cycle engine according to the present invention, and FIG. 1 is a sectional view taken along the line AA. A cylinder 2 is attached to the upper part of the crankcase 1, and a cylinder head 3 is attached to the upper part of the cylinder 2. A crankcase cover 4 is attached to a side surface of the crankcase 1, and a crank chamber 5 surrounded by the crankcase 1 and the crankcase cover 4 is formed. A crankshaft 6 rotatably supported by bearings (not shown) is rotatably housed in the crank chamber 5, and a piston 7 reciprocating in the cylinder 2 has a connecting rod 8 in the crankshaft 6. Are connected through. A camshaft 11 whose both ends are rotatably supported by ball bearings 9 and 10 which are bearings is rotatably accommodated in the crank chamber 5, and a cam gear fixedly press-fitted to one end of the camshaft 11. 12 and a crank gear 1 press-fitted and fixed to one end of the crankshaft 6.
3 and 3 are in mesh. The number of teeth of the cam gear 12 is set to be twice the number of teeth of the crank gear 13, and the cam shaft 11 has an intake cam 14 and an exhaust cam for opening and closing an intake valve and an exhaust valve, which will be described later. And 15 are fixed.

A rocker cover 16 is attached to the upper portion of the cylinder head 3, and a valve operating mechanism housing space 17 is formed in the rocker cover 16. An intake valve 18 and an exhaust valve (not shown) attached to the cylinder head 3 are provided in the valve mechanism storage space 17.
Spring 19 for urging the valve toward the valve closing direction, intake valve 18
Rocker arm 2 that biases the exhaust valve and the exhaust valve in the opening direction
No. 0, and a valve mechanism 25 including push rods 23 and 24, one end of which abuts on the rocker arm 20 and the other end of which abuts on the intake cam 14 and the exhaust cam 15 via the tappets 21 and 22, is housed. ing. The rocker arm 20 is swingably attached to the upper portion of the cylinder head 3 by an adjusting screw 26.

The cylinder head 3 has an intake port 27 communicating with the inside of the cylinder 2 when the intake valve 18 is opened and an exhaust port communicating with the inside of the cylinder 2 when the exhaust valve is opened (not shown). ) And are formed. The intake port 27, the valve mechanism storage space 17, and the space portions 28 and 29 for arranging the push lots 23 and 24 formed in the cylinder head 3 and the cylinder 2 are A mixture passage 30 that connects the crank chamber 5 and the inside of the cylinder 2 is formed. The crank chamber 5 and the space 29 are communicated with each other by a communication hole 31 and a passage described later.

Next, a carburetor 32 is provided which is equipped with a diaphragm pump and which is a mixture forming section for forming a mixture containing lubricating oil by mixing liquid fuel mixed with lubricating oil and air. The carburetor 32 and the crank chamber 5 are connected by an intake passage 33 that supplies the air-fuel mixture containing the lubricating oil formed in the carburetor 32 to the crank chamber 5. A reed valve 3 that allows only the air-fuel mixture to flow from the carburetor 32 side to the crank chamber 5 side is provided at a connection portion between the intake passage 33 and the crank chamber 5.
4 is provided, and the reed valve 34 is formed by a valve body 34a and a valve stopper 34b.

A support wall 35 for supporting the ball bearing 9 is formed on the crankcase 1, and a passage 36 is formed between the support wall 35 and the inner wall surface of the crankcase 1. Has been done. Meanwhile, a support wall 37 for supporting the ball bearing 10 is formed on the crankcase cover 4, and a passage 38 is formed between the support wall 37 and the inner wall surface of the crankcase cover 4. There is. And these passages 36, 3
8 communicates with the space 29. A gap 39, which is a passage hole through which the air-fuel mixture passes, is formed between the outer ring and the inner ring of the ball bearings 9 and 10. Further, the cam gear 12 is formed with a passage hole 40 through which the air-fuel mixture passes.

In such a structure, during the compression stroke in which the piston 7 rises, the air-fuel mixture sucked into the cylinder 2 in the previous suction stroke is compressed. on the other hand,
Since the inside of the crank chamber 5 is in a negative pressure state as the piston 7 rises, the reed valve 34 is opened, and the air-fuel mixture formed in the carburetor 32 containing the lubricating oil is introduced into the intake passage 3
It flows through the inside of 3 and flows into the crank chamber 5. During the compression stroke, the intake valve 18 and the exhaust valve are closed.

Next, during the explosive stroke in which the compressed air-fuel mixture explodes in the cylinder 2, the intake valve 18 and the exhaust valve are maintained in the closed state, the piston 7 descends, and the piston 7 descends. As a result, the pressure in the crank chamber 5 and the mixture passage 30 rises. The crank chamber 5
The reed valve 34 is closed in accordance with the increase in the internal pressure, and the high-pressure mixture in the crank chamber 5 is prevented from flowing back to the carburetor 32 side.

During the exhaust stroke for discharging the combustion gas, the piston 7 rises while the intake valve 18 is kept closed and the exhaust valve is opened, so that the combustion gas in the cylinder 2 is exhausted from the exhaust port. Emitted into the atmosphere. It should be noted that, during this explosion stroke, the inside of the crank chamber 5 and the like are decompressed as the piston 7 rises, but the reed valve 34 is maintained in a closed state because the pressure is not reduced to a negative pressure state.

Next, during the intake stroke in which the intake valve 18 is opened and the exhaust valve is closed and the piston 7 descends, the mixing in the crank chamber 5 pressurized as the piston 7 descends. Air is sucked into the cylinder 2 through the air-fuel mixture passage 30.

As described above, with the operation of the four-cycle engine, the air-fuel mixture containing the lubricating oil formed in the carburetor 32 flows into the crank chamber 5 and is sucked into the cylinder 2 through the air-fuel mixture passage 30. Therefore, the valve mechanism 25 accommodated in each part of the crank chamber 5 and the valve mechanism accommodating space 17 which is a part of the mixture passage 30 is lubricated by the lubricating oil contained in the mixture. . The arrows shown in FIG. 2 indicate the flow of the air-fuel mixture from the carburetor 32 through the crank chamber 5 into the cylinder 2.

Here, the arrow shown in FIG. 1 indicates the crank chamber 5.
It shows the flow of air-fuel mixture in the crank chamber 5
Most of the air-fuel mixture inside passes through the communication hole 31 and the air-fuel mixture passage 3
0, but part of the air-fuel mixture in the crank chamber 5 flows into the air-fuel mixture passage 30 through the passages 36 and 38. Then, the air-fuel mixture passing through the passages 36 and 38 is
Since it passes through the passage hole 40 formed in 2 and the gap 39 between the ball bearings 9 and 10 and enters the passages 36 and 38, the ball bearings 9 and 1 formed by the lubricating oil contained in the air-fuel mixture.
0 lubrication is also performed well, and seizure of the ball bearings 9 and 10 due to poor lubrication is prevented.

Therefore, the oil pan for storing the lubricating oil for lubricating the respective parts in the crank chamber 5 is not required, and the lubricating oil does not leak even when the 4-cycle engine is tilted upside down. A portable work machine equipped with a 4-cycle engine can be used in all positions. Furthermore, a dedicated lubrication mechanism for lubricating the valve mechanism 25 is also unnecessary.

By eliminating the need for an oil pan for storing lubricating oil, it is possible to reduce the size and weight of the 4-cycle engine, and to suppress the increase in weight as compared with the 2-cycle engine as much as possible. Therefore, the maintenance and the like are as easy as the two-cycle engine. Moreover, since no oil pan is provided, a large amount of lubricating oil does not adhere to the inner wall of the cylinder 2,
Since it is not necessary to attach an oil ring to the piston 7 and the oil ring is not required, the piston 7
Sliding resistance is reduced and output is improved.
Generation of vibration is reduced by reducing the weight of the reciprocating sliding portion.

Further, since the lubricating oil contained in the air-fuel mixture is sucked into the cylinder 2 little by little and burns, "blown-out" as seen in the two-cycle engine using the mixed fuel containing the lubricating oil. No white smoke is generated from the muffler, and the exhaust gas and smoke components are almost the same as in a 4-cycle engine having an oil pan.

In the present embodiment, the formation of the air-fuel mixture containing the lubricating oil has been described by taking as an example the case of forming the air-fuel mixture by mixing the liquid fuel mixed with the lubricating oil and the air. In 32, a mixture of fuel and air is mixed to form a mixture containing no lubricating oil, and the mixture is supplied in a spray form to form a mixture containing lubricating oil. Good.

Next, a second embodiment of the present invention will be described with reference to FIGS. The same parts as those described with reference to FIGS. 1 to 3 are designated by the same reference numerals, and the description thereof will be omitted. In this embodiment, the camshaft 1 is attached to the support wall 35 of the crankcase 1 and the support wall 37 of the crankcase cover 4.
Forming bearing holes 41 and 42, which are bearing portions for supporting 1
A bearing member such as a ball bearing is omitted.
The bearing holes 41, 4 are formed in the support walls 35, 37.
A passage hole 43 is formed which communicates with the air passage 2 and through which the air-fuel mixture passes.

In such a structure, most of the air-fuel mixture in the crank chamber 5 passes through the communication hole 31 and the air-fuel mixture passage 30.
Although it flows in, a part of the air-fuel mixture in the crank chamber 5 flows into the air-fuel mixture passage 30 through the passages 36 and 38. Then, the air-fuel mixture passing through the passages 36 and 38 is
The inner peripheral surfaces of the bearing holes 41, 42 due to the lubricating oil contained in the air-fuel mixture, because they enter the passages 36, 38 through the passage holes 40 formed in the above and the passage holes 43 communicating with the bearing holes 41, 42. Of the bearing hole 4 due to poor lubrication
The wear and seizure of 1, 42 and the camshaft 11 are prevented.

Further, since a bearing member such as a ball bearing is not used, the cost reduction and the number of assembling steps can be achieved by reducing the number of parts.

In the present embodiment, the case where the passage holes 43 are formed one by one has been described as an example, but as shown in FIG. 6, two or more passage holes 43 may be formed. . If the area through which the air-fuel mixture passes becomes sufficiently large as the number of the passage holes 43 increases, the communication hole 31 is omitted and all the air-fuel mixture is passed through the passages 36 and 38.
0, so that the inner peripheral surfaces of the bearing holes 41, 42 can be lubricated more satisfactorily.

Further, in the present embodiment, the case where the passage holes 43 are made to communicate with the bearing holes 41 and 42 which axially support both ends of the cam shaft 11 has been described as an example. When the mounted working machine is not used at all positions but is used as a vertical type, for example, the lubricating oil separated from the air-fuel mixture is likely to accumulate on the lower side, and the lubricating oil causes the bearing hole 4
Since the lubrication of 1 and 42 is performed, it is not necessary to form the passage hole 43 and the passages 36 and 38 on the lower side. Similarly, when the working machine equipped with the four-cycle engine of the first embodiment is used as a vertical type, the passages 36 and 38 may not be formed on the lower side.

[0030]

As described above, the invention according to claim 1 has a four-cycle having a crank chamber in which a crankshaft and a camshaft to which a cam gear is fixed are housed, and the internal pressure fluctuates with the reciprocating movement of the piston. In the engine, since the intake passage for supplying the air-fuel mixture containing the lubricating oil formed in the air-fuel mixture forming portion to the crank chamber is provided and the air-fuel mixture passage communicating the crank chamber with the inside of the cylinder is provided, the air-fuel mixture is The crank chamber can be lubricated by the air-fuel mixture containing the lubricating oil contained therein. Therefore, it is not necessary to provide an oil pan for storing the lubricating oil for lubricating the crank chamber. A portable work machine that can be used in all positions without leaking out lubricating oil no matter what direction the mobile work machine equipped with In addition, the four-cycle engine can be made smaller and lighter by eliminating the need for an oil pan, and the end portion of the camshaft is pivotally supported while being located in the crank chamber. Since a passage hole through which the air-fuel mixture passes is formed in the bearing portion, and a passage is formed between the bearing portion and the inner peripheral surface of the crank chamber and the passage is communicated with the air-fuel mixture passage, When the lubricating oil flows into the air-fuel mixture passage, at least a part of the air-fuel mixture passes through the passage hole of the bearing portion into the passage, and flows into the air-fuel mixture passage through this passage,
The bearing portion of the camshaft can be satisfactorily lubricated, and the wear and seizure due to poor lubrication can be prevented.

According to the second aspect of the present invention, as described above, in the first aspect of the present invention, since the cam gear is formed with the passage hole through which the air-fuel mixture passes, the lubricating oil in the crank chamber flows into the air-fuel mixture passage. At this time, at least a part of the air-fuel mixture passes through the passage hole of the cam gear and the passage hole of the bearing portion to reach the inside of the passage, and flows into the air-fuel mixture passage through this passage, so that it is hidden behind the cam gear. It is possible to satisfactorily perform the lubrication of the bearing portion, and it is possible to reliably prevent the occurrence of wear and seizure due to poor lubrication of the bearing portion.

[Brief description of drawings]

1 is a sectional view taken along the line AA in FIG. 2 showing a first embodiment of the present invention.

FIG. 2 is a vertical sectional front view showing the first embodiment of the present invention.

FIG. 3 is a side view showing a cam gear.

FIG. 4 is a vertical sectional side view showing a second embodiment of the present invention.

5 is a cross-sectional view taken along the line BB in FIG.

FIG. 6 is a front view showing a modification of the second embodiment.

[Explanation of symbols]

 2 Cylinder 5 Crank chamber 6 Crankshaft 7 Piston 9, 10, 41, 42 Bearing part 11 Camshaft 12 Cam gear 30 Mixture passage 32 Mixture forming part 33 Intake passage 36, 38 Passage 39, 43 Passage hole 40 Passage hole

Claims (2)

[Claims] 1. A four-cycle engine having a crank chamber in which a crankshaft and a camshaft to which a cam gear is fixed are housed and whose internal pressure fluctuates in accordance with the reciprocating movement of a piston is lubricated by a mixture forming portion. An intake passage for supplying an air-fuel mixture to the crank chamber is provided, an air-fuel mixture passage communicating the crank chamber and the cylinder is provided, and the end portion of the camshaft is axially supported while being located in the crank chamber. A passage hole through which air-fuel mixture passes is formed in the bearing portion, and a passage is formed between the bearing portion and the inner peripheral surface of the crank chamber, and the passage is communicated with the air-fuel mixture passage. Lubricator for 4-cycle engine. 2. A lubrication device for a four-cycle engine according to claim 1, wherein a passage hole through which the air-fuel mixture passes is formed in the cam gear.