JP3209486B2 - Lubrication system for four-stroke engine - Google Patents

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 hand-held four-stroke engine mainly used as a power source for a trimmer or a chain saw.

[0002]

2. Description of the Related Art As a conventional handheld engine, a two-stroke engine capable of ensuring good lubricating performance even in any engine posture such as tilting and rollover is widely used.

[0003]

In recent years, however, the use of a four-stroke engine has been demanded as a hand-held engine from the viewpoint of exhaust gas purification. However,
In a four-stroke engine, it is necessary to store oil exclusively for lubrication. If this oil is used in a hand-held type, it can reliably lubricate each part of the engine in any engine position, and can also provide excess oil to the crank chamber and valve operating chamber. It is necessary to suppress refueling to prevent power loss.

An object of the present invention is to provide a lubricating device for a four-stroke engine which can satisfy such a demand.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is directed to an engine in any engine posture.
Oil or oil mist into the crankcase, oil sump, valve train,
It can be circulated to the rank chamber to lubricate each part of the engine.
A lubrication system for Unishi was four-cycle engine, the crankcase defining a crank chamber, perpendicular to the crankshaft
A cross section of a horseshoe is formed to form an oil sump surrounding the crank chamber, and between the two chambers, a first oil feeding means for transporting oil or oil mist from the crank chamber to the oil sump is provided. And a valve operating chamber formed on one side of the cylinder block are communicated with each other through a communication pipe projecting a fixed length into the oil reservoir, and a valve operating valve is provided between the valve operating chamber and the crank chamber. A first feature is that a second oil feeding means for transporting oil or oil mist from the chamber to the crank chamber is provided.

[0006] The present invention, in addition to the above features, open during boosting of the crank chamber shall be the second, characterized in that to constitute a first oil feeding means by the check valve closing during decompression.

[0007]

According to the first feature, in any engine posture, the first and second lubricating means allow the crank chamber-
Oil or oil mist is circulated through the oil reservoir, the valve operating chamber, and the crank chamber to lubricate engine parts such as a crankshaft, a piston, and a valve operating device. Moreover, the oil reservoir is horseshoe-shaped so as to surround the crankcase.
Having a large volume and a communication pipe connected to the valve train
By projecting into the oil reservoir for a predetermined length, the engine
In each position, the oil is pumped from the crankcase oil
A predetermined amount can be temporarily stored in the storage chamber, thereby suppressing excessive oil supply to the crank chamber and the valve operating chamber.

[0008] According to a second aspect of the present invention, it is possible to transport the oil or oil mist from the crank chamber to the oil reservoir chamber by utilizing the pressure pulsations of the crank chamber, the oil pump is Ru unnecessary der.

[0009]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view of a hand-held four-stroke engine provided with the lubricating device of the present invention, and FIG.
2 and 3 and 4 are lines 3-3 and 4-4 in FIG.
It is a line sectional view.

First, in FIG. 1, a carburetor 2 and an exhaust muffler 3 are mounted on the left and right sides of an engine body 1 of a hand-held four-stroke engine E, respectively, and an air cleaner 4 is mounted on an inlet of the carburetor 2 at an intake path. You. A fuel tank 5 is mounted on the front surface (the lower surface in FIG. 1) of the engine body 1. The carburetor 2 is provided with a diaphragm pump for pumping up fuel from the fuel tank 5 by utilizing pressure pulsation of a crank chamber described later of the engine E and returning excess fuel to the tank 5. Fuel can be supplied to the intake port of E.

2 to 4, the engine body 1
A crankcase 6 formed by joining a pair of upper and lower case halves 6a and 6b with bolts;
And a cylinder block 7 integrated with a head, which is coupled through a rear wall (an upper wall in FIG. 2). The two case halves 6a and 6b are provided with a crankshaft 8 whose axis is directed vertically.
And a piston 10 connected to the crankpin of the crankshaft 8 via a connecting rod 9 is slidably fitted to a cylinder 7a formed in the cylinder block 7.

On the top wall of the cylinder 7a, there are formed an intake port 11 and an exhaust port 12 connected to the carburetor 2 and the exhaust muffler 3, respectively.
Suction and exhaust valves 13 and 14 for opening and closing the valves 1 and 12 are provided. A valve operating device 15 for driving the intake and exhaust valves 13 and 14 is provided in a valve operating chamber 16 formed on the lower side of the crankcase 6 and the cylinder block 7. The valve operating chamber 16 can be opened and closed by a head cover 21 joined to the head of the cylinder block 7.

The valve gear 15 is supported by a drive timing gear 17 fixed to the crankshaft 8 and a support shaft 19 mounted on the crankcase 6 at an intermediate portion of the valve gear chamber 16 so that the drive timing gear 17 A driven timing gear 18 driven at a reduction ratio of 1/1, a cam 20 integrally connected to one end of the driven timing gear 18,
0, a pair of cam followers 23 and 24 supported on a cam follower shaft 22 provided on the cylinder block 7 and a rocker shaft 25 provided on the head of the cylinder block 7 and one end of each. A pair of rocker arms 26 and 27 to be brought into contact with the valve heads of the intake and exhaust valves 13 and 14, a pair of push rods 28 and 29 for connecting the cam followers 23 and 24 to the other ends of the rocker arms 26 and 27, respectively; Intake and exhaust valve 1
Valve springs 30 and 3 for urging the valves 3 and 14 in the valve closing direction, respectively.
The intake valve 13 is opened during the intake stroke of the piston 10, and the exhaust valve 14 is opened during the exhaust stroke.

The crankcase 6 includes a crankshaft 8.
A crank chamber 32 for accommodating the crank pin and the crank web, and an oil reservoir 33 (see FIG. 3) having a horseshoe-shaped cross section orthogonal to the crank shaft 8 and surrounding the crank chamber 32 are formed. Check valve 35 in partition 34 between
Is provided. This check valve 35 is connected to the crank chamber 32.
The valve opens when the pressure rises and closes when the pressure decreases.
Constitutes a first oil feeding means .

The check valve 35 is connected to both the case halves 6a, 6a.
b, a base plate 37 to be mounted in mounting grooves 36, 36 formed respectively on the opposing surfaces of the partition walls 34, 34, and a reed which opens and closes a valve hole 37a of the base plate 37 in response to pressure pulsation of the crank chamber 32. A valve plate 38 and a stopper plate 39 for regulating the maximum opening position of the reed valve plate 38 are provided. One end of the reed valve plate 38 and one end of the stopper plate 39 overlap with each other on the oil reservoir 33 side to overlap the base plate 37. Screwed into.

The crankcase 6 is provided with a communication pipe 40 projecting a predetermined length from the oil reservoir chamber 33 to communicate the chamber 33 with the valve operating chamber 16 . Shirin the valve chamber 16 to of, et al.
To the crank chamber 32 via the cylinder 7a of the double lock 7
Communication hole 4 opened on the inner peripheral surface of cylinder 7a for communication
The communication hole 41 is raised in the cylinder 7a.
When the piston 10 descends, it closes when it descends, and when it rises
The second oil feeding means is configured to open. That is, a communication hole 41 that connects the valve operating chamber 16 to the crank chamber 32 is formed in the fitting portion between the crankcase 6 and the cylinder block 7, and the communication hole 41 is opened and closed by the piston 10 that moves up and down. It has become.

The cylinder block 7 has a breather pipe 4 whose inner end protrudes a predetermined length into the valve operating chamber 16 on the head side.
2, the outer end of which is outside air or the air cleaner 4.
Opened inside.

As shown in FIG. 2, a known recoil starter 43 capable of cranking the crankshaft 8 is mounted on the upper part of the crankcase 6. Also the crankshaft 8
A rotor 46 with cooling blades 45 of the flywheel magneto 44 is fixed to the lower end of the flywheel, and an ignition coil 47 cooperating with the rotor 46 is fixed to the cylinder block 7.

A centrifugal clutch 49 is interposed between the rotor 46 and the working machine drive shaft 48. The centrifugal clutch 49 includes a plurality of clutch shoes 50 pivotally supported by the rotor 46 so as to be able to expand, a clutch spring 51 for urging the clutch shoes 50 in a diameter reducing direction, and a drive shaft 48 surrounding the clutch shoes 50.
When the rotor 46 rises above a predetermined number of revolutions, the clutch shoe 50 expands in diameter and presses against the inner peripheral surface of the clutch drum 52 to reduce the output torque of the crankshaft 8. It can be transmitted to the drive shaft 48.

The engine body 1 has a shroud 5 covering the lower surface and the head thereof together with the flywheel magneto 44.
3 is mounted, and a cooling air passage 54 is defined between the engine 3 and the engine body 1. The inlet 54 of the cooling air passage 54
a is open toward the ventilation passage 56 between the engine body 1 and the fuel tank 5, and the outlet 54b is connected to the starter 4
Open to the third side.

When the rotor 46 rotates, the wind generated by the cooling blades 45 flows through the ventilation passage 56 and the cooling air passage 54, and the oil reservoir 33, the fuel tank 5, the valve operating chamber 1
6 and the cylinder block 7 can be cooled.

In the figure, reference numeral 57 denotes a lubricating oil, and 58 denotes an oil filler cap of the oil reservoir 33.

Next, the operation of this embodiment will be described.

FIG. 2 shows an attitude of the engine E when the drive shaft 48 of the work machine is driven to perform the work, and the valve train 16 is directed downward. At this time, the lubricating oil 57 is stored in the crank chamber 32, the oil reservoir 33, and the valve operating chamber 16.
There is an appropriate amount.

According to the operation of the engine E, the pulsation of pressure occurs in the crank chamber 32 due to the elevating movement of the piston 10, and the check valve 37 is opened when the pressure is increased and the check valve 37 is closed when the pressure is reduced. The oil or oil mist in the chamber 32 is intermittently fed to the oil reservoir 33 through the check valve 37, and accordingly, the oil or oil mist in the oil reservoir 33 is also transmitted through the communication pipe 40.
Pumped intermittently.

The communication hole 41 is opened during the ascent stroke of the piston 10 to communicate the valve operating chamber 16 with the crank chamber 32. Oil mist is sucked into the crank chamber 32.

As described above, the lubricating oil 57 repeatedly circulates through the crank chamber 32, the oil reservoir chamber 33, the valve operating chamber 16 and the crank chamber 32 due to the pressure pulsation of the crank chamber 32, and the crankshaft 8, the piston 10, and the valve operating valve are repeated. Each part of the engine such as the device 15 can be lubricated. Moreover, the communication pipe 40 is the oil reservoir 33
In the oil sump 33, a certain amount of oil sent from the crank chamber 32 is stored in the oil sump 33 to prevent excessive accumulation of oil in the crank chamber and to prevent the oil from flowing into the operation valve chamber 16. The amount of oil supply can be limited. Thus, power loss due to excessive lubrication of the crankshaft 8 and the like and the valve train 15 can be prevented.

On the other hand, since the inner end of the breather pipe 42 is projected into the valve operating chamber 16 for a predetermined length, the breather pipe 42 does not sink into the oil stored in the chamber 16. Therefore, crankcase 1
Blow-by gas generated in the valve operating chamber 16 together with oil
Is separated from the oil and discharged from the breather pipe 42 to the outside or the air cleaner 4.

During the operation of the engine E, the valve operating chamber 16 is turned upward as shown in FIG. 5 or the carburetor 2 and the exhaust muffler 3 are moved up and down as shown in FIG. Head cover 2 as shown in FIG.
Even when 1 is turned downward, the lubricating oil or oil mist circulates inside the engine E in the same manner as described above. At this time, the oil sump 33 has a horseshoe shape so as to surround the crank chamber 32, has a relatively large volume, and the communication pipe 40 connected to the valve operating chamber 16 projects into the oil sump 33 for a predetermined length. In this manner, the oil pumped from the crank chamber 32 in each of the above positions of the engine E is
Once, and a supply amount to the valve operating chamber 16 can be limited.

As shown in FIG. 8, when the engine E has the oil reservoir 33 facing downward, the communication pipe 40 is immersed in the oil in the oil reservoir 33, and the oil reservoir 33 and the valve train Although the same level of oil accumulates in the oil 16, in such a state, only a part of the drive timing gear 17 of the valve gear 15 is immersed in the oil, and no excessive oil supply to the gear 15 occurs.

In the above embodiment, various design changes can be made without departing from the gist of the present invention. For example, the valve train accommodated in the valve train chamber may be of the SV type or OHC type. As the check valve 35, a ball valve type or a flat valve type can be used.

[0033]

As described above, according to the first aspect of the present invention , oil or oil is not affected in any engine posture.
Lumist to crank chamber, oil sump chamber, valve chamber, crank chamber
And circulate so that each part of the engine can be lubricated.
A lubricating device for a cycle engine. The crankcase that defines the crankcase has a section perpendicular to the crankshaft.
An oil sump is formed in the shape of a horseshoe and surrounds the crankcase, and between the two chambers, first oil feed means for transporting oil or oil mist from the crankcase to the oil sump is provided. A valve operating chamber formed on one side of the block communicates with the oil reservoir via a communication pipe projecting a fixed length from the oil reservoir, and a crankshaft is provided between the valve operating chamber and the crank chamber. Since the second oil feeding means for transporting oil or oil mist to the chamber is provided, the oil or oil mist is circulated to the crank chamber, the oil sump chamber, the valve operating chamber, and the crank chamber in any engine posture, and each part of the engine is controlled. Can be lubricated , and the oil sump can surround the crankcase.
Having a relatively large volume in the shape of a horseshoe,
And the communication pipe connected to the valve train protrudes into the oil reservoir
This allows the oil pumped from the crank chamber to temporarily store a predetermined amount of oil in the oil reservoir in each position of the engine , thereby suppressing excessive lubrication to the crank chamber and the valve operating chamber, and Power loss of the crankshaft and the valve gear can be prevented.

According to the second feature of the present invention, the first oil feed means is constituted by the check valve which opens when the pressure in the crank chamber is increased and closes when the pressure in the crank chamber is reduced. can make the transport of oil or oil mist to the oil reservoir chamber, an oil pump is not required, that obtained contribute to cost reduction.

[Brief description of the drawings]

FIG. 1 is a plan view of an engine provided with a lubrication device of the present invention.

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

FIG. 3 is a sectional view taken along line 3-3 in FIG. 2;

FIG. 4 is a sectional view taken along line 4-4 in FIG. 2;

FIG. 5 is an explanatory view of a lubrication operation in an engine posture in which a valve operating chamber is directed upward.

FIG. 6 is an explanatory diagram of a lubrication operation in an engine posture in which a carburetor and an exhaust muffler are vertically oriented.

FIG. 7 is an explanatory diagram of a lubrication operation in an engine posture in which a cylinder block head is directed downward.

FIG. 8 is an explanatory view of a lubrication operation in an engine posture in which the oil reservoir is turned downward.

[Explanation of symbols]

E engine 6 crankcase 7 cylinder block 8 crankshaft 15 valve operating system 16 operating chamber 32 the crank chamber 33 the oil reservoir chamber 35 check valve (first oil feeding means) 40 communication pipe 10 and 41 the piston and the communication hole (second feed Oil means) 42 Breather tube

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-199208 (JP, A) JP-A-5-171915 (JP, A) JP-A-61-39417 (JP, U) (58) Survey Field (Int.Cl. ⁷ , DB name) F01M 1/04 F01M 13/00

Claims (2)

(57) [Claims] (1) In any engine posture,
Oil or oil mist into the crank chamber (32) and oil sump chamber (3).
3), circulated to the valve chamber (16) and the crank chamber (32).
Four cycles to allow the engine parts to be lubricated
An engine lubrication system, wherein a crankcase (6) defining a crankcase (32) is provided.
The cross section perpendicular to the crankshaft (8) is horseshoe-shaped
An oil reservoir (33) surrounding the crank chamber (32) is formed, and between the two chambers (32, 33), a first oil or oil mist is transported from the crank chamber (32) to the oil reservoir (33). An oil feeding means (35) is provided, and an oil sump (33) is provided.
A valve operating chamber (16) formed on one side of the cylinder block (7) communicates with the oil reservoir (33) via a communication pipe (40) projecting a fixed length, and is further operated. Valve room (1
6) and a second oil feeding means (10, 41) for transporting oil or oil mist from the valve operating chamber (16) to the crank chamber (32) between the crank chamber (32) and the crank chamber (32). Lubrication device for four-cycle engine. 2. A four-stroke engine according to claim 1, wherein the first oil feed means is constituted by a check valve (35) which opens when the crank chamber (32) is pressurized and closes when the crank chamber (32) is depressurized. lubrication equipment.