JP2002339715A - Lubricating device of four-cycle engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To certainly lubricate a sliding surface between a cam and a cam follower that slide each other under a harsh condition even when an engine tilts in any direction. SOLUTION: An opening 45 of a supply flow channel 43 for supplying oil mist of an oil reserving chamber 42 to a cam chamber 14 is opened toward an outer peripheral surface 22a of the cam 22. The inner surface of the cam chamber 14 is provided with oil guiding walls 54 and 55 that are arranged so as to surround the outer peripheral surface 22a of the cam 22 in its proximity and guide oil mist from the opening 45 to the outer peripheral surface 22a of the cam 22. Thus, the oil mist supplied from the oil reserving chamber 42 can be easily supplied from the opening 45 of the supply flow channel 43 to the outer peripheral surface 22a of the cam 22 in the cam chamber 14. The cam 22 is surrounded with the oil guiding walls 54 and 55 near the outer peripheral surface 22a, so that fly of the oil stuck to the cam 22 is suppressed and the cam 22 and the cam followers 25a and 25b can be certainly lubricated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricating device for a four-cycle engine mainly used for a portable working machine or the like.

[0002]

2. Description of the Related Art For example, drive engines used in portable working machines such as chain saws, lawnmowers, and mowers include:
In general, a two-stroke engine is employed because of its simple structure and light weight. However, 2
In the case of a cycle engine, there is a problem that the amount of hydrocarbons in the exhaust gas discharged to the atmosphere is large, and this is a bottleneck in purifying the exhaust gas and preserving the environment. On the other hand, in the case of the four-cycle engine, the amount of hydrocarbons in the exhaust gas is smaller than in the case of the two-cycle engine. The low noise is also advantageous in terms of the working environment. For this reason, recently, adoption of a four-stroke engine has been studied for portable work machines such as a chain saw and a mower.

The invention described in Japanese Patent Application Laid-Open No. 10-288019 has been proposed as a lubricating device for a four-cycle engine mounted on a portable working machine. According to the same publication, even when the engine is tilted, the negative pressure generated during the upward stroke of the piston is used to feed oil from the oil storage chamber to the crank chamber, and convert the oil in the crank chamber into oil mist to make various parts of the engine. Is described.

[0004]

However, Japanese Patent Application Laid-Open No. 10-288
In the lubricating apparatus for a four-stroke engine described in Japanese Patent Publication No. 019, the oil supplied to the crank chamber is scattered by the centrifugal force of the crank gear (valve driving gear) and the cam gear, and the cam for opening and closing the supply / exhaust valve is provided. It is difficult for oil to reach the contact surface with the cam follower. Thereby, the cam and the cam follower are easily worn.

[0005] The working posture of a chain saw, a mower or the like greatly changes depending on the application, and accordingly, the engine posture also greatly changes up and down, left and right, and upside down. Therefore, it can be driven regardless of how the engine is tilted.
A cycle engine is required.

SUMMARY OF THE INVENTION It is an object of the present invention to reliably lubricate a sliding surface between a cam and a cam follower that slide under severe conditions regardless of how the engine is tilted.

[0007]

According to the first aspect of the present invention,
A cam follower for opening and closing an intake valve and an exhaust valve provided on the cylinder head side and a cam for driving the cam follower are provided in a cam chamber, and an oil storage chamber is provided by utilizing pressure fluctuation of a crank chamber due to reciprocating motion of a piston. In a lubricating device for a four-stroke engine configured to supply oil mist to a lubricating unit including the cam chamber from above and to recirculate oil mist from the lubricating unit to the oil storage chamber,
An opening on the cam chamber side of a supply passage for supplying oil mist from the oil storage chamber to the cam chamber is opened toward an outer peripheral surface of the cam, and an inner peripheral surface of the cam has an outer peripheral surface of the cam. Is provided so as to surround the oil mist near the outer peripheral surface thereof, and an oil guide wall for guiding oil mist from the opening to the outer peripheral surface of the cam is provided.

Accordingly, the oil mist supplied from the oil storage chamber is supplied from the opening of the supply passage toward the vicinity of the outer periphery of the cam in the cam chamber, and the cam is surrounded by the oil guide wall near the outer peripheral surface. Therefore, scattering of oil adhering to the cam is suppressed.

According to a second aspect of the present invention, in the first aspect of the present invention, the position of the opening is determined below the cam in an upright engine state.

Therefore, when the engine is tilted, the oil mist is held by the oil guide wall near the outer peripheral surface of the cam, and when the engine is tilted in the opposite direction, the oil guide is kept up to that point. The oil mist held by the wall can be dropped on the cam.

According to a third aspect of the present invention, in the first or second aspect, the oil guide wall extends to the vicinity of the cam follower.

Therefore, it is possible to effectively guide the oil mist toward the contact portion between the cam and the cam follower.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. 1 is a vertical side view of a four-cycle engine, FIG. 2 is a vertical side view of a four-cycle engine, FIG. 3 is a vertical front view taken along line AA in FIG. 1, and FIG.
5, FIG. 5 is a vertical sectional front view taken along the line CC in FIG. 1, FIG. 6 is a horizontal sectional view showing the inside of the valve operating chamber, FIG. 7 and FIG. FIG. 9 is a horizontal sectional view showing the inside of the valve operating chamber, and FIG.
It is a vertical front view in a line part.

The engine body 1 of the four-cycle engine is
It has a crankcase 2, a cylinder block 3 fixed to the upper part thereof, a cylinder head 4 formed integrally with the cylinder block 3, and a rocker cover 5 attached to the upper part of the cylinder head 4. The crankcase 2 is divided into two parts in the axial direction of the crankshaft 9 with a center of a cylinder 10 described later as a boundary. The two divided crankcases 2a and 2b are integrally connected via a liquid gasket. Is formed.
A portion surrounded by the divided crankcases 2a and 2b is a crankcase 6.

A crankshaft 9 supported by a bearing 7 and a bearing 8 sealed on one side is provided in the crank chamber 6.
A piston 11 that reciprocates in a cylinder 10 formed therein is connected via a connecting rod 12. Further, a cam chamber 14 is formed in the split crankcase 2b by a bearing 8 and a partition wall 13 sealed on one side. A crank gear 15 is fixed to the crank shaft 9. Further, both ends of the crankshaft 9 have the crank chamber 6.
The crankshaft 9 is projected outside and the split crankcase 2
Oil seals 16 and 17 are attached to portions penetrating through a and 2b. A flywheel 19 having a cooling fin 18 for air cooling is fixed to one end of the crankshaft 9.
At the other end, a recoil starter pulley 20 for starting the engine
Is attached.

The cam chamber 14 is provided with a cam gear 21 meshed with the crank gear 15, and the cam gear 21 is integrally provided with a cam 22 which also functions as an intake cam and an exhaust cam. The cam chamber 14 is formed by the cylinder block 3, the divided crankcase 2b, and the cam chamber cover 23. The cam gear 21 is rotatably supported by a cam shaft 24 supported by the cylinder block 3. Further, a pair of cam followers 25 that rotate in synchronization with the rotation of the cam 22 are provided.
a and 25b (see FIGS. 2 and 3) are swingably supported by a cam follower shaft 26 supported by the cylinder block 3.

The space covered by the rocker cover 5 in the upper part of the cylinder head 4 is a valve operating chamber 27 in which the intake valve 2 supported by the cylinder head 4 is located.
8 and an exhaust valve 29, a spring 30 for urging them in the valve closing direction, and rocker arms 31a and 31b for pressing the intake valve 28 and the exhaust valve 29 in the valve opening direction are housed therein (FIGS. 2 to 6). 4).

The cam chamber 14 and the valve chamber 27 are communicated by push rod passages 33a and 33b. The push rod passages 33a and 33b accommodate push rods 32a and 32b having one ends in contact with the rocker arms 31a and 31b and the other ends in contact with the cam followers 25a and 25b. An intake port 34 for supplying air-fuel mixture to the combustion chamber in the cylinder 10 and an exhaust port 35 for exhausting exhaust gas from the combustion chamber are formed in the cylinder head 4 (see FIG. 5). . A carburetor 36 and an air cleaner 37 are sequentially connected to a tip of the intake port 34, and a muffler 38 is connected to a tip of the exhaust port 35 (see FIG. 2). Also,
A spark plug 39 is attached to the cylinder 10. The cowling 40 is provided so as to cover the components, guide cooling air generated from the cooling fins 18 for air cooling, and cool the components.

An oil tank 41 is fixed below the crankcase 2. As shown in FIGS. 1 and 3, an oil storage chamber 42 for storing lubricating oil is formed in the oil tank 41. ing. The connection between the oil storage chamber 42 and the cam chamber 14 is connected by a supply passage 43 that supplies the oil mist generated in the oil storage chamber 42 to the cam chamber 14. One end of the supply channel 43 is connected to a supply channel 44 inserted into the oil storage chamber 42.
The other end is opened as an opening 45 near the outer peripheral surface 22 a of the cam 22 of the cam chamber 14. The position of the opening 45 is below the cam 22 in the upright engine state in which the cylinder head 4 is located at the top.

The leading end of the supply flow path 44 inserted into the oil storage chamber 42 is disposed at a substantially central part in the oil storage chamber 42. A support shaft 46 is rotatably mounted between the supply passage 44 and the cap 47 of the oil tank 41. The support shaft 46 has an air supply port 48 for supplying the air in the oil storage chamber 42 to the cam chamber 14, and a throttle 4 having a reduced inner diameter near the air supply port 48.
9 are formed. A flexible pipe 50 having flexibility is attached to the support shaft 46, and a passage 51 connected to the flexible pipe 50 is communicated with a throttle 49, and air and oil are condensed by the throttle 49. Are mixed to convert the oil into mist.

An oil inlet 52 is formed at the distal end of the flexible pipe 50, and a weight 53 is fixed to the outer periphery of the oil inlet 52. That is, by displacing the weight 53 as the inclination of the engine body 1 changes, the support shaft 46 is rotated to deflect the flexible pipe 50,
As a result, the oil suction port 52 always moves to the bottom of the oil storage chamber 42, which is the lowermost part in the vertical direction, so that the oil mist generated by the throttle part 49 is supplied to the cam chamber 14 through the supply flow path 43 under pressure. It is configured to be.

As shown in FIG. 3, an opening 45 of the supply passage 43 on the cam chamber 14 side is opened toward the outer peripheral surface 22a of the cam 22 on which the cam followers 25a and 25b slide. Oil guide wall 54 provided on the cylinder part and oil guide wall 5 provided on the cylinder block 3
5 and the cam guides 25a, 25
5b, the oil guide wall 5
A narrow space 56 is formed by the cam followers 25a and 25b. The oil guide walls 54 and 55 are disposed symmetrically so as to surround the cam 22 from both sides near the outer peripheral surface 22a.

After the oil mist supplied to the cam chamber 14 lubricates the respective parts in the cam chamber 14, the oil mist is sent to the valve chamber 27 through the push rod passages 33a and 33b. It is configured to diverge into a bypass passage 57 that communicates with the crank chamber 6. The flow of the oil mist at this time is shown by arrows in FIG.

Specifically, as shown in FIGS. 4 and 5, between the valve operating chamber 27 and the crank chamber 6, oil mist supplied into the valve operating chamber 27 is supplied via a breather device 58. An oil recirculation path 59 is provided for recirculation in the crank chamber 6. The oil return path 59 is formed by the cylinder block 3 and the crankcase 2 and is connected to a cylinder opening 60 communicating with the cylinder 10. Also, the intake valve 28
In the vicinity of the exhaust valve 29, oil suction pipes 61 and 62 extending from the breather device 58 to substantially the bottom of the valve operating chamber 27 are provided. Specifically, as shown in FIG. 5, the intake valve 28 and the exhaust valve 29 are slidably fitted by cylindrical valve guides 28a and 29a projecting from the bottom of the valve operating chamber 27, and the oil intake pipe 61 , 62 are formed with openings 61a, 62a which are lower than the upper ends of the valve guides 28a, 29a and open near the bottom surface of the valve chamber 27. These oil suction pipes 61 and 62 are connected to an oil return path 59.

The cylinder opening 60 is formed at a position which is closed by the lowering of the piston 11 and is opened when a negative pressure is generated in the crank chamber 6 by the raising of the piston 11. The cylinder opening 60 and the piston 11
As a result, the oil mist is moved from the valve operating chamber 27 to the crank chamber 6.
Acts as a check valve that only allows oil to be pumped inside.

As shown in FIG. 3, the bypass passage 57 that connects the cam chamber 14 and the crank chamber 6 has an opening 63 at one end connected to the push rod passages 33a and 33b at the top of the cam chamber 14. The other end is communicated with the cylinder opening 60 similarly to the oil recirculation path 59 (see FIG. 4).

An oil guide wall 64 is provided in the cam chamber 14 along the outer periphery of the cam gear 21, and an oil guide passage 66 is provided between the opening 63 of the bypass passage 57 of the cam chamber 14 and the guide wall 65. . The guide wall 65 is the cam gear 2
1 are provided along a substantially tangential direction.

Between the crank chamber 6 and the oil storage chamber 42 of the oil tank 41, recovery flow paths 67a and 67b for recovering the oil in the crank chamber 6 into the oil storage chamber 42.
And are connected by These recovery channels 67a, 6
As shown in FIG. 5, 7b is formed at two places, an upper part and a lower part of the crankcase 2. These recovery channels 67
The leads a and 67b open and close due to pressure fluctuations in the crank chamber 6, and allow only oil mist and blow-by gas generated in the crank chamber 6 to be fed from the crank chamber 6 to the oil storage chamber 42. It is connected via a valve 68. The reed valve 68 has a structure that opens as the pressure in the crank chamber 6 increases. The tip of the recovery flow path 67b connected to the oil storage chamber 42 is
And a return hole 69 (FIG. 1, FIG. 1) for returning the collected oil mist into the oil storage chamber 42.
FIG. 3) is formed.

In the oil storage chamber 42, the oil mist and the blow-by gas are constantly discharged to a space above the oil level 70. Here, by making the amount of oil in the oil storage chamber 42 equal to or less than the specified amount, the return hole 69 and the air supply port 48 located at a substantially central portion in the oil storage chamber 42 It is structured so that it will not be immersed in the oil surface 70 even if it is inclined in this manner. Accordingly, the reverse flow of the oil lubricating the inside of the engine or only the oil does not enter the supply flow path 44, and the concentration of the oil mist can be kept constant at all times. In addition, the oil that has lubricated the inside of the engine is returned to the oil storage chamber 42, and new oil is supplied, so that the oil can be changed satisfactorily.

The breather device 58 is provided inside the rocker cover 5 and has a partition plate 71, a breather 72, and a breather pipe 73. The breather pipe 73 is provided on the rocker cover 5, one end of which is connected to the breather device 58, and the other end of which is connected to the air cleaner 37 as shown in FIG. The discharged blow-by gas passes through the air cleaner 37 and the carburetor 36 and is burned again.

As shown in FIG. 1 and FIG.
Has a gas-liquid separation chamber 74 for separating blow-by gas and oil at the center. At the corner of the gas-liquid separation chamber 74, FIG.
A plurality of holes 75 are opened as shown in FIG. A plurality of passages 76 are formed by the groove 72 a provided in the breather 72 and the partition plate 71, and these passages 76 extend to the corners and communicate with a plurality of holes 77 formed in the partition plate 71. . All the passages 76 are oil recirculation passages 5 communicating with the crank chamber 6.
9 is communicated.

A ceiling chamber 78 is formed between the partition plate 71 of the breather 72 and the rocker cover 5 to store oil when the engine body 1 is inverted. A plurality of grooves 79 for flowing oil are also formed in the ceiling chamber 78 (see FIG. 8), and these grooves 79 are also connected to the breather 72 by a plurality of holes 77 formed in the partition plate 71.

In such a configuration, during operation of the four-cycle engine, a strong negative pressure is generated in the crank chamber 6 as the piston 11 rises, and the cylinder opening 60 is opened. Thus, the breather device 5 in the valve chamber 27
From 8, the oil mist passes through the oil recirculation path 59, and is sucked into the crank chamber 6 through the cylinder opening 60 and the cylinder 10. Oil mist is also drawn into the crank chamber 6 from the opening 63 (see FIG. 3) of the cam chamber 14 through the bypass passage 57 and the cylinder opening 60 and the cylinder 10.

In the lowering stroke of the piston 11, when the pressure in the crank chamber 6 increases with the lowering,
The reed valve 68 opens, and oil mist is discharged from the crank chamber 6 to the oil storage chamber 42 through the recovery flow paths 67a and 67b to recover oil. These recovery channels 67a, 6
7b are provided at two locations, an upper portion and a lower portion, of the crank chamber 6, and the recovery flow path 67 is provided even when the engine body 1 is in an inverted state.
a, 67b so that oil does not accumulate in the crank chamber 6. At the same time, the pressure in the oil storage chamber 42 increases, so that the air in the oil storage chamber 42
6, a negative pressure is generated in the throttle portion 49, the oil is sucked up from the flexible pipe 50, and the air and the oil are mixed in the throttle portion 49 to convert the oil into mist. The generated oil mist and blow-by gas are supplied to the cam chamber 14 under pressure.

The oil mist and the blow-by gas fed to the cam chamber 14 lubricate the cam 22, the cam gear 21, and the crank gear 15, and pass through the push rod passages 33a and 33b as shown by arrows in FIG. 27
Is supplied within. After the oil mist supplied into the valve operating chamber 27 lubricates the components in the valve operating chamber 27, a strong negative pressure is generated in the crank chamber 6 by the rise of the piston 11, and the cylinder opening 60 which functions as a check valve is opened. When opened, as shown by the arrow in FIG. 5, the oil mist is discharged from the breather device 58, the oil return path 59, the cylinder opening 60,
It is sucked into the crank chamber 6 via the cylinder 10. At this time, a part of the oil mist is supplied into the crank chamber 6 via the cam chamber 14, the bypass passage 57, the cylinder opening 60, and the cylinder 10. The above is the flow of the oil mist of the entire engine.

Here, lubrication in the cam chamber 14 will be described. As described above, when the oil mist and the blow-by gas generated in the oil storage chamber 42 are pressure-fed to the cam chamber 14 through the supply channels 43 and 44, the opening 45 of the supply channel 43 is shown in FIG. So that the cam followers 25a and 25b
Is opened toward the outer peripheral surface 22a of the cam 22 on which the oil mist slides, so that the oil mist reliably adheres to the sliding surface 22a of the cam 22. Thereby, lubrication between the cam 22 and the cam followers 25a and 25b can be reliably performed.

Here, for example, the opening 45 of the supply channel 43
Is open in the vicinity of the crank gear 15, the oil mist is scattered by the centrifugal force of the crank gear 15, the cam gear 21 and the cam 22, and the oil mist is separated from the cam 22 and the cam followers 25a and 25b. In some cases, the lubricating oil is not supplied sufficiently, resulting in insufficient lubrication and burning. However, in the present embodiment, since the cam 22 is surrounded by the oil guide walls 54 and 55 near the outer peripheral surface 22a, the oil mist does not scatter and adheres to the outer peripheral surface 22a of the cam 22 reliably. Thereby, the cam 22
In addition, the cam followers 25a and 25b can be reliably lubricated, and the reliability of both can be improved.

[0038]

According to the first aspect of the present invention, the supply flow path for supplying the oil mist of the oil storage chamber to the cam chamber has its opening opened toward the outer peripheral surface of the cam, and the inner surface of the cam chamber is opened. Is provided so as to surround the outer peripheral surface of the cam near the outer peripheral surface thereof, and an oil guide wall for guiding the oil mist from the opening to the outer peripheral surface of the cam is provided. Can be easily supplied to the outer peripheral surface of the cam in the cam chamber from the opening of the supply flow path. Further, since the cam is surrounded by the oil guide wall near the outer peripheral surface, the oil adhering to the cam is scattered. , And the cam and the cam follower can be reliably lubricated.

According to the second aspect of the present invention, in the first aspect of the present invention, since the position of the opening is determined below the cam in the upright state of the engine, when the engine is inclined, When the engine is tilted in the opposite direction, the oil mist held by the oil guide wall is dropped onto the cam when the oil mist is held by the oil guide wall near the outer peripheral surface of the cam. Therefore, the lubrication of the cam and the cam follower can be further ensured.

According to the third aspect of the present invention, in the first or second aspect of the present invention, since the oil guide wall extends to the vicinity of the cam follower, the oil mist is directed toward the contact portion between the cam and the cam follower. Can be guided effectively.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view of a four-cycle engine according to an embodiment of the present invention.

FIG. 2 is a vertical sectional side view of the four-cycle engine.

FIG. 3 is a vertical sectional front view taken along line AA in FIG. 1;

FIG. 4 is a vertical sectional side view taken along a line BB in FIG. 2;

FIG. 5 is a vertical sectional front view taken along the line CC in FIG. 1;

FIG. 6 is a horizontal sectional view showing the inside of the valve chamber.

FIG. 7 is a horizontal sectional view showing the inside of a breather device and a valve operating chamber.

FIG. 8 is a horizontal sectional view showing the inside of a breather device and a valve operating chamber.

FIG. 9 is a vertical sectional front view taken along the line DD in FIG. 1;

[Explanation of symbols]

 Reference Signs List 4 Cylinder head 6 Crank chamber 9 Crankshaft 11 Piston 22 Cam 25a, 25b Cam follower 28 Intake valve 29 Exhaust valve 42 Oil storage chamber 43 Supply channel 45 Opening 54, 55 Oil guide wall

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshio Hirabayashi 1-1-1, Ishiba, Matsumoto, Nagano Pref. Ishikawajima Shibaura Machinery Co., Ltd. Matsumoto Plant (72) Inventor, Masatake Tanimoto 1-1-1, Ishiba, Matsumoto, Nagano Pref. No. Ishikawajima Shibaura Machinery Co., Ltd. Matsumoto Factory F-term (reference) 3G013 AA04 AB03 BA02 BA04 BB12 BC11 BD01

Claims (3)

[Claims] A cam follower for opening and closing an intake valve and an exhaust valve provided on a cylinder head side and a cam for driving the cam follower are provided in a cam chamber, and pressure fluctuation in the crank chamber due to reciprocating motion of a piston is used. A lubricating device for a four-stroke engine configured to supply oil mist from an oil storage chamber to a lubrication unit including the cam chamber, and to return oil mist from the lubrication unit to the oil storage chamber. An opening on the cam chamber side of a supply flow path for supplying oil mist from a storage chamber to the cam chamber is opened toward an outer peripheral surface of the cam, and an inner peripheral surface of the cam chamber has an outer peripheral surface of the cam. An oil guide wall disposed so as to surround the outer peripheral surface and guiding an oil mist from the opening to the outer peripheral surface of the cam. Lubrication system of cycle engine. 2. The four-stroke engine lubrication system according to claim 1, wherein the position of the opening is defined below the cam in an upright engine state. 3. The four-stroke engine lubrication system according to claim 1, wherein the oil guide wall extends to a position near the cam follower.