JP4139247B2 - 4-cycle engine lubrication system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lubrication device for a four-cycle engine, and more particularly, a lubrication device for a small four-cycle engine used in a portable brush cutter, a back-type power sprayer, or the like in which an inclined position is one of working positions. About.
[0002]
[Prior art]
In general, an engine that is a driving source of a work machine that is carried by or carried on the back of a worker, such as a portable brush cutter (trimmer) or a backpack-type power sprayer for plants, tilts the work machine. It is necessary to operate stably even when In a two-cycle engine, which is a type of engine, for example, a reed valve that uses a negative pressure generated when the piston is raised uses a negative pressure generated by mixing the fuel and lubricating oil into the engine. In addition, since a mechanism for lubricating each movable part is provided, a structure that can be used at any angle can be easily realized. As in this example, the two-cycle engine is widely used in the portable work machine. On the other hand, four-cycle engines, which are other types of engines, can be made smaller and lighter due to advances in design and processing technology, but most of them have an oil reservoir (oil pan) that is a component of the lubrication device as a crank. Since it is provided at the lower part of the chamber and lubricates each movable part by splashing oil from the position or pumping it up with a pump, it is basically used in an upright state. In other words, the degree of freedom in the slope operation is inferior to that of the two-cycle engine.
However, the two-cycle engine has problems such as a large amount of hydrocarbons in the exhaust gas and a large noise.
In recent years, there has been an increasing demand for exhaust gas purification and prevention of deterioration of the working environment, and the two-cycle engine is becoming unable to meet the demand. For this reason, it has been awaited the establishment of a technique for increasing the degree of freedom in tilting operation so that a four-cycle engine having good exhaust gas characteristics and low noise can be used for a portable work machine.
Therefore, the present applicant has previously proposed a lubrication device for a four-cycle engine that utilizes the change in the pressure in the crank chamber in accordance with the lifting and lowering operation of the piston (for example, Patent Document 1).
In this proposal, the oil reservoir chamber and the crank chamber are completely shut off, and the crank chamber and the oil reservoir chamber are communicated with a part of the rotation trajectory of the crankshaft from the oil reservoir chamber. Provided with intermittent oil feeding means for sucking oil from the oil reservoir chamber and feeding it into the crank chamber, and as a configuration of the oil feeding means, a passage for communicating between the crank chamber and the oil reservoir chamber when the crank chamber becomes negative pressure A configuration in which is provided inside the crankshaft is employed.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-288019 (paragraph “0023” column, FIG. 1)
[0004]
[Problems to be solved by the invention]
In the configuration disclosed in Patent Document 1, although there is an advantage that lubrication in the crank chamber and the valve operating chamber can be performed only by using a pressure change in the crank chamber, there is a possibility that the device structure becomes relatively large.
That is, there is a passage formed in the crankshaft as one of the communication passages between the crank chamber and the oil reservoir chamber. For this reason, as a size of the crankshaft, a dimension for securing the passage is required in addition to a dimension capable of securing the strength, and as a result, the diameter dimension of the crankshaft must be increased. In addition, it is necessary to have a passage shape that does not penetrate in the axial direction inside the crankshaft, but bends in the radial direction in the middle, and it is necessary to improve the alignment accuracy between the passages. There is also.
[0005]
The object of the present invention is to effectively reduce the pressure in the crank chamber without increasing the size, making the structure complicated, and increasing the processing cost in view of the problems in the above-mentioned conventional four-cycle engine, particularly the small four-cycle engine lubrication device. Another object of the present invention is to provide a lubricating device for a four-cycle engine that can be used for lubrication.
[0006]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided a lubricating device for a four-cycle engine, a crank chamber (5) for accommodating a piston (8) from an oil reservoir chamber (6) in which lubricating oil is stored, and a valve drive unit (10). ), In a four-cycle engine lubrication device that circulates oil in the order of the valve train chamber (11) and lubricates the engine, a crank chamber (6) and a crank chamber (5) are provided between the oil reservoir chamber (6) and the crank chamber (5). 5) Separately from the mist passage (14) for supplying oil mist into the oil supply passage (13), there is an oil supply passage (13) for feeding oil stored in the oil reservoir (6) into the crank chamber (5). A suction portion (30) provided in the oil reservoir chamber (6) of the oil feed passage (13) is moved by gravity as the engine is inclined and is stored in the oil reservoir chamber (6). The oil supply passage (13) The opening (13A) opened in the inner chamber (5) is opened along with the movement of the piston (8) while the piston (8) moves from the position near the top dead center toward the top dead center, It is arranged at a position to supply oil in the oil reservoir (6) pumped up through the oil feed passage (13) by the negative pressure in the crank chamber (5) into the crank chamber (5). It is said.
[0008]
Lubrication system for a four-cycle engine according to the invention described in claim 2 is the lubrication system for a four-cycle engine according to claim 1, before Symbol oil feed opening of the passage (13) (13A) is at the top dead center position It is characterized in that it is located on the bottom dead center side of the skirt (8A) of a certain piston (8).
[0009]
The lubrication system for a four-cycle engine according to the invention described in claim 3, in the lubricating device of a four-cycle engine according to any one of claims 1 or 2, before Symbol oil feed passage (13), a crank chamber ( that 5) in the check valve is opened by the oil reservoir chamber (6) you permit oil feeding the oil in the crank chamber (5) (19) is connected only when a negative pressure It is a feature.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram for explaining a lubrication path of a four-cycle engine using a lubrication apparatus according to an embodiment of the present invention. In particular, FIG. 1 shows a case where the piston is located at the top dead center.
[0011]
As shown in FIG. 1, a four-cycle engine 1 includes an oil reservoir provided in the vicinity of a crank chamber 5 and a crankcase 4 that are configured by a cylinder block 3 and a crankcase 4 in which a cylinder head 2 is integrated. And a chamber 6.
The oil reservoir chamber 6 is partitioned with respect to the crankcase 4 to form a sealed space as a whole.
[0012]
In FIG. 1, a later-described suction portion 30 is provided in the oil reservoir 6, and a one-way valve 40 is provided in the crankcase 4. The one-way valve 40 is responsive to a pressure change in the crank chamber 5. When there is no pressure change, the oil reservoir chamber 6 is closed so that no oil leaks to the outside even if the oil reservoir chamber 6 is in any inclined state.
[0013]
As shown in FIG. 1, a crankshaft 7 is rotatably supported on the cylinder block 3 and the crankcase 4. A piston 8 connected to a crank pin of the crankshaft 7 via a connecting rod is slidably inserted in a cylinder 3 </ b> A provided inside the cylinder block 3.
[0014]
In FIG. 1, an intake port and an exhaust port communicating with a carburetor (not shown) and an exhaust muffler (not shown) are formed on the upper wall of the cylinder 3A, and an intake valve for opening and closing the port is formed in each port. And an exhaust valve (in FIG. 1, only one valve is indicated by the symbol V for convenience).
As shown in FIG. 1, the valve drive unit 10 for driving these valves is composed of components such as a valve drive gear 10A, a cam gear 10B, and a rocker arm (not shown).
Among these components of the valve drive unit 10, the valve drive gear 10 </ b> A and the cam gear 10 </ b> B are connected to the cylinder block 3 so that the valve operating chamber 11 formed in the head of the cylinder block 3 and the crank chamber 4 communicate with each other. It is disposed in a communication path 12 formed on a side portion with the crankcase 5.
[0015]
Between the cylinder block 3 and the oil reservoir chamber 6, an oil feeding means including a suction part 30 and an oil feeding passage 13 is provided.
In FIG. 1, the suction part 30 is composed of a tubular body 30A that can be easily bent by an elastic material such as rubber, and a weight 30B with a suction port provided at the tip thereof. In other words, the weight 30B can always move vertically downward due to its gravity, so that even if the oil reservoir 6 is inclined, the tip portion is immersed below the oil level of the oil. It can be made to.
[0016]
The oil feed passage 13 in which one opening is positioned in the suction portion 30 is located in the cylinder block 3 as the position of the other opening 13A when the crank chamber 4 is negatively pressured. The position where the inside of the chamber 4 communicates is set.
The other opening 13 </ b> A in the oil feed passage 13 connects the inside of the crank chamber 4 and the oil reservoir 6 to the oil from the oil reservoir 6 when the inside of the crank chamber 4 tends to become negative pressure due to the rise of the piston 8. This is the part that can be pumped up and introduced into the crank chamber 4. Therefore, the position of the opening 13A is a position where the piston 8 is fully opened when it reaches the vicinity of the top dead center, and the bottom dead center direction side of the skirt portion 8A below the piston 8 located in the vicinity of the top dead center (see FIG. 1 on the right). Accordingly, the opening 13A is fully opened when the piston 8 reaches the vicinity of the top dead center, and this state is maintained until the piston 8 reaches the top dead center.
[0017]
The opening 13A is not only provided at a position where the piston 8 can be fully opened at a position near the top dead center, but is gradually opened from the time when the piston 8 reaches near the top dead center until reaching the top dead center. It can also be provided at a position where the area can be increased. That is, the opening 13A begins to open when the piston 8 reaches the vicinity of the top dead center, gradually increases the opening area until reaching the top dead center, and is fully opened when the top dead center is reached. Provide in position.
On the other hand, on the side of the cylinder block 3 facing the opening of the opening 13A, an opening 14A having substantially the same shape as the opening 13A is opened. The opening 14A and the oil reservoir 6 are separated by a mist passage 14. It is communicated.
An opening portion 14B in the oil reservoir chamber 6 of the mist passage 14 opens at a substantially central portion of the oil reservoir chamber 6, and oil mist is mainly sucked from the opening portion 14B. In FIG. 1, reference numeral 20 denotes a check valve similar to the check valve 19.
[0018]
The one-way valve 40 described above is provided between the crank chamber 4 and the communication passage 12, and the inside of the crank chamber 4 is brought to a negative pressure by the valve hole drilled in the lower portion of the crankcase 4 and the piston 8 rising. It is constituted by a valve plate 40A that closes the valve hole when it becomes.
[0019]
On the other hand, in FIG. 1, a breather pipe 15 is provided in the upper part of the cylinder block 3. One end of the breather pipe 15 is opened and connected in the valve operating chamber 11, and the other end is connected to the air cleaner 16. ing.
The valve operating chamber 11 is provided with a return oil passage 17. One end of the return oil passage 17 opens into the valve operating chamber 11 and the other end is disposed in the oil reservoir chamber 6.
The other end of the return oil passage 17 located in the oil reservoir chamber 6 is positioned at a substantially central position in the thickness dimension S of the oil reservoir chamber 6. The amount of oil accommodated in the oil reservoir 6 is defined such that the other end of the return oil passage 17 is always positioned above the oil level. Thus, even when the oil reservoir chamber 6 is inclined or laid down, the other end of the return oil passage 17 is opened above the oil level so that the oil can be recirculated.
The same applies to the opening portion 14B of the mist passage 14 described above. The air cleaner 16 is also provided with a return oil passage 18 for returning the oil gas-liquid separated by the oil separator 16 </ b> A to the oil reservoir 6.
[0020]
Since the present embodiment is configured as described above, when the valve operating chamber 11 of the engine 1 is positioned upward and is in a so-called upright state, the crank chamber 4 is used when the piston 8 is not in the up-and-down operation. In the oil reservoir 6 and the valve operating chamber 11, appropriate amounts of lubricating oil are accumulated. When the engine 1 changes from an upright state to an inverted state or an inclined state, the weight 30B of the oil supply section 30 can move to a position where oil is stored in the oil reservoir chamber 6, so that the position is always in the oil. And maintain a state where the oil can be pumped up. Further, since the amount of oil in the oil reservoir chamber 6 is such that the opening of the return oil passage 17 always protrudes from the oil liquid surface, the oil return passage is maintained even in a non-upright state. The state of allowing the oil to recirculate from the valve operating chamber 11 to the oil reservoir 6 is maintained without being immersed in the oil. As a result, it is possible to prevent a situation in which the amount of oil circulation to other parts due to excessive oil in the valve operating chamber 11 is insufficient.
[0021]
When the engine 1 is started, a pressure change occurs in the crank chamber 4 due to the raising / lowering operation of the piston 8, the crank chamber 4 is depressurized and tends to be negative when the piston 8 is raised, and when the piston 8 is lowered, the crank chamber 4 is pressurized and positive. It becomes a pressure tendency.
[0022]
When the crank chamber 4 tends to have a negative pressure, a differential pressure is generated between the crank chamber 4 and the oil reservoir chamber 6, and the opening 13A of the oil feed passage 13 begins to open as the piston 8 moves to near the top dead center. When the piston 8 moves to near the top dead center, it is fully opened. As a result, the negative pressure in the crank chamber 4 acts in the oil feed passage 13, so that the oil is sucked from the oil reservoir chamber 6 and sent toward the crank chamber 4. The oil feed passage 13 is fully open until the piston 8 moves from the vicinity of the top dead center to the top dead center position, so that the negative pressure in the crank chamber 4 is sufficiently applied, and the oil feed is performed. The amount can be sufficient.
[0023]
The oil sent into the crank chamber 4 is pulverized by the piston 8 and the crankshaft 7 to become oil mist.
[0024]
In FIG. 1, when the piston 8 descends, the crank chamber 4 becomes positive pressure and a differential pressure is generated between the crank chamber 4 and the oil reservoir chamber 6.
In this case, the valve plate 40A of the one-way valve 40 opens the valve hole, and the oil mist accumulated in the crank chamber 4 and the cylinder 3A together with the pressurized air is sent from the crank chamber 4 to the communication passage 12.
The oil mist sent to the communication passage 12 is sent to the valve operating chamber 11 by positive pressure and lubricates each part of the valve drive unit 10 in the middle.
The oil mist that has lubricated each component of the valve driving unit 10 reaches the valve operating chamber 11, the air in the oil reservoir 6 is sucked in from the passage 14, and the oil in the oil reservoir 6 is sucked in by the oil filler 30. As a result, the oil reservoir chamber 6 becomes negative pressure, and is recovered to the oil reservoir chamber 6 side through the return passage 17.
Further, part of the oil mist and blow-by gas in the valve operating chamber 11 is released into the air cleaner 16 through the breather pipe 15, and is separated into oil and blow-by gas, air to the intake system, and oil to the oil reservoir chamber 6 To be recovered.
[0025]
In the present embodiment, a check valve 19 is provided in the oil feed passage 13 provided between the crank chamber 4 and the oil reservoir chamber 6.
The check valve 19 is open when the inside of the crank chamber 4 becomes negative pressure and has a habit of allowing oil to flow from the oil reservoir 6, and when the inside of the crank chamber 4 becomes positive pressure. Is closed to prevent backflow from the crank chamber 4 and to enable smooth supply of oil.
The narrow tube 21 is a small-diameter passage that communicates the bottom of the crankcase 4 and the case 22 of the valve drive unit 10 to discharge residual oil in the crankcase 4 to the case 22 when the engine stops rotating. Is the passage.
[0026]
In this embodiment, as a configuration for lubrication in the crank chamber 4, the oil flow path using the negative pressure in the crank chamber 4 is fully opened or gradually opened by moving the piston 8 near the top dead center. Since the opening of the configuration to be enlarged is merely connected to the crank chamber, unlike the case where oil supply means in the crank chamber is provided on the crankshaft, machining becomes extremely easy.
Incidentally, FIG. 2 is a configuration shown in Japanese Patent Application Laid-Open No. 2002-276321, which is a prior application of the present applicant. In this configuration, an oil discharge portion that opens by moving the top dead center position of the piston 8 (for convenience, 2 (indicated by reference numeral 13A ′ in FIG. 2) (in the same publication, paragraph “0029” column), as a flow path to the oil discharge section 13A ′, the recirculated oil from the valve operating chamber 11 and the oil reservoir chamber ( For the sake of convenience, there is a possibility that the piping path becomes complicated because the oil flow path from 6) is combined with the oil flow path. On the other hand, in the present embodiment, a single flow path from the oil reservoir 6 to the crank chamber 4 is sufficient, so that the configuration and processing become extremely simple.
[0027]
【The invention's effect】
According to the first aspect of the present invention, as a configuration for lubricating the crank chamber, it is only necessary to provide an oil feed passage that can pump up oil from the oil reservoir chamber when the crank chamber becomes negative pressure. There is no need to form a passage into the crankshaft. As a result, it is possible to obtain a lubricating device that can reduce the increase in cost by making the lubricating structure simple and preventing the device from becoming large and complicated.
[0028]
According to the second and third aspects of the present invention, the oil feeding passage having a configuration in which the opening area is gradually changed in the vicinity of the top dead center in the vicinity of the top dead center until the piston reaches the top dead center. Therefore, it is possible to ensure the maximum amount of lubrication when the negative pressure in the crank chamber is maximum.
[0029]
According to the fourth aspect of the present invention, the oil feed passage is provided with the check valve that is opened only when the crank chamber has a negative pressure, so that the oil can be smoothly supplied.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a state where a piston is at a top dead center in order to explain a lubrication path in a four-cycle engine to which a lubrication apparatus according to an embodiment of the present invention is applied.
FIG. 2 is a schematic diagram showing a lubrication path in a 4-cycle engine for explaining a difference in operation from the embodiment shown in FIG. 1;
[Explanation of symbols]
1 Engine 4 Crank chamber 6 Oil reservoir chamber 8 Piston 11 Valve chamber 13 Oil feed passage 13A Opening 19 Check valve

Claims (3)

The oil is circulated in the order of the crank chamber (5), the valve drive unit (10), and the valve operating chamber (11) for accommodating the piston (8) from the oil reservoir (6) in which lubricating oil is stored. In a 4-cycle engine lubrication system that performs internal lubrication ,
Separated from the mist passage (14) for supplying oil mist into the crank chamber (5), the oil is stored in the oil reservoir (6) between the oil reservoir (6) and the crank chamber (5). An oil feed passage (13) is provided for feeding oil into the crank chamber (5),
The suction part (30) located in the oil reservoir (6) of the oil feeding passage (13) moves by gravity with the inclination of the engine and is stored in the oil reservoir (6). While the piston (8) moves from the position close to the top dead center toward the top dead center, the opening (13A) that is always located at the center and is opened in the crank chamber (5) of the oil feed passage (13). The oil in the oil reservoir chamber (6), which is opened with the movement of the piston (8) and pumped up through the oil feed passage (13) by the negative pressure in the crank chamber (5), is supplied to the crank chamber (5). ) Is located in the position to supply in,
A lubrication device for a four-cycle engine. In the lubricating device of a four-cycle engine according to claim 1, before Symbol oil feed opening of the passage (13) (13A) is the bottom dead center direction of the skirt portion of the piston (8) in the top dead center position (8A) A lubricating device for a four-cycle engine, characterized in that it is located on the side. In the lubricating device of a four-cycle engine according to any one of claims 1 or 2, before Symbol oil feed passage (13), a crank chamber (5) inside is opened only when a negative pressure oil reservoir chamber (6) the crank chamber (5) lubrication system for a four-cycle engine and a check valve permit oil feed oil (19) is connected to the.

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