JP3127352B2 - 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, and more particularly, to an engine body having a crank chamber and a valve operating chamber. A dry sump type in which an oil sump chamber for storing lubricating oil to be sequentially supplied to the chamber is provided, and the valve operating chamber and the oil sump chamber are communicated via a return oil passage for returning the lubricating oil from the valve operating chamber to the oil sump chamber. It relates to improvement of a lubrication device.

[0002]

2. Description of the Related Art As a conventional hand-held type engine, any operating posture of the engine, such as tilting and rollover, can be used.
Two-stroke engines capable of exerting a lubricating function are widely used.

[0003]

However, in recent years, from the viewpoint of exhaust gas purification, the use of a four-stroke engine as a handheld engine has been demanded. However,
In a four-stroke engine, it is necessary to store oil exclusively for lubrication. Therefore, if this oil is used in a hand-held type, it is necessary to reliably lubricate each part of the engine regardless of the operating posture of the engine. It is desirable to employ a dry sump lubrication device for such a four-stroke engine.

[0004] However, hand-held engines are
When it is not in use, it may be left sideways or in an upside-down state.If a conventional dry sump type lubrication device is used as it is, the valve-operating chamber may be placed sideways or in an upside-down state. If the engine is left unattended for a long time, the oil stored in the oil storage chamber will flow back through the return path and will enter a large amount into the valve operating chamber and leak out from the breather tube or the like.

The present invention has been made in view of the above circumstances, and can easily prevent backflow of lubricating oil from an oil reservoir to a valve operating chamber even when the engine is left sideways or left standing in an inverted state. An object of the present invention is to provide a dry sump lubrication device for an engine.

[0006]

In order to achieve the above object, the present invention provides an oil reservoir for storing lubricating oil to be sequentially supplied to a crank chamber and a valve operating chamber in an engine body having a crank chamber and a valve operating chamber. Rutotomoni provided a chamber, to the oil reservoir chamber, the lubricating oil
Oil mist generation means for generating oil mist from
And volume, the valve operating chamber in which a substantially atmospheric pressure state, between the oil reservoir chamber,
From the bottom of the valve operating chamber through an orifice into the oil reservoir chamber communicated with via a return passage for returning the lubricating oil, an opening into the oil reservoir chamber of the return path, the valve operating chamber of the oil reservoir chamber When the engine is turned downside down or in an inverted state, the opening is arranged so as to be exposed above the oil level of the lubricating oil in the oil sump , and the space between the oil sump and the crank chamber is located above the oil level of the oil sump. Through holes
Between the crankcase and the valve operating chamber.
Through a control valve that opens when the pressure rises and closes when the pressure drops,
The pressure in the crank chamber is Pc, the pressure in the oil reservoir is Po, and the valve train is
When the pressure of the Pv, equation P during engine operation
It is characterized in that c ≦ Po <Pv is satisfied .

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

FIG. 1 is a perspective view showing an example of use of a hand-held type four-stroke engine provided with a lubricating apparatus according to the present invention, FIG. 2 is a longitudinal sectional front view of the four-stroke engine, and FIGS.
FIG. 3 is a sectional view taken along line 3-3 to 9-9 in FIG.

First, as shown in FIG. 1, a hand-held four-stroke engine E is mounted on a drive unit of the power trimmer T, for example, as a power source. Power trimmer T
Is used by turning the cutter in various directions depending on the working state, so that the engine E is also greatly tilted each time,
Or, it is turned upside down, and the driving posture is not constant.

2 and 3, a carburetor 2 and an exhaust muffler 3 are attached to an engine body 1 of the engine E before and after it, respectively, and an air cleaner 4 is attached to an inlet of the carburetor 2 at an intake path. . A fuel tank 5 is mounted on the lower surface 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.

In FIG. 2 and FIG.
Comprises a cylinder block 6 integrated with a head, and a crankcase 7 joined to a lower end surface of the cylinder block 6. The cylinder block 6 has a single cylinder 9 for accommodating a piston 8 at the center, and has a number of cooling fins 10 on its outer periphery.

The crankcase 7 includes a pair of upper and lower case halves 7a and 7b, each of which is provided with a plurality of bolts 11 arranged on the periphery thereof.
The crankshaft 13 connected to the piston 8 via the connecting rod 12 is supported between the two case halves 7a and 7b as follows.

That is, the upper case half 7a has a pair of left and right upper journal walls 14, 14 'hanging from its ceiling wall.
The lower case half 7b integrally has a pair of left and right lower journal support walls 15, 15 'rising from the bottom wall thereof and facing the upper journal walls 14, 14'. The left and right journal portions of the crankshaft 13 are sandwiched by the upper and lower journal support walls 14 and 15 via a plain bearing 16, and the right and left journal portions of the crankshaft 13 are supported by the upper and lower journal support walls 14 ′ and 15 ′. The part is pinched via the ball bearing 17. Upper and lower journal support walls 14, 14 '; 15, 1
5 ′ is provided with a total of four bolt holes 18 penetrating vertically through the crankcase 7 with the plain bearing 16 or the ball bearing 17 interposed therebetween. Stud bolts 19 are implanted in the lower end surface of the cylinder block 6. Nuts 20 are screwed onto the lower ends of these stud bolts 19 protruding from the lower surface of the crankcase 7, whereby the upper
The lower journal support walls 14, 14 '; 15, 15' are connected to each other, and the cylinder block 6 and the crankcase 7 are also connected to each other.

Since such a coupling structure does not interfere with the cooling fins 10 on the outer periphery of the cylinder block 6, the number, size, etc. of the cooling fins 10 can be freely selected.
The air cooling effect of the engine E can be sufficiently enhanced. In addition, the support rigidity of the crankcase 7 with respect to the crankshaft 13 can be increased.

Oil seals 21, 21 ′ are mounted on both end walls of the crankcase 7 so as to penetrate the crankshaft 13.

In the interior of the crankcase 7, the upper and lower journal support walls 14, 14 '; 15, 15' allow the left oil reservoir 22, the central crank chamber 23, and the right valve operating chamber in FIG. The crank chamber 23 is provided with a crank portion 13 a of the crank shaft 13. A predetermined amount of lubricating oil O is stored in the oil reservoir 22, and is stirred and scattered by an oil slinger 25 (oil mist generating means).
Is fixed to the crankshaft 13.

As shown in FIGS. 2 and 4, the oil slinger 25 includes a boss 25a fitted to the crankshaft 13;
It comprises a plurality of long arm blades 25b and short arm blades 25c protruding from the outer periphery thereof.
The tips of 5c are bent to the opposite sides in the axial direction.

The oil slinger 25 having such a structure is as follows.
In any driving posture of the engine E, the two blades 25
The oil stored in the oil reservoir 22 is stirred by the rotation of the b and 25c, so that an oil mist can be always generated.

The valve chamber 24 extends to the head through one side of the cylinder block 6, and the upper part of the valve chamber 24 is opened and closed by a head cover 26 joined to the head of the cylinder block 6. It is possible.

As shown in FIGS. 2 and 5, suction and exhaust ports 27 and 28 connected to the carburetor 2 and the exhaust muffler 3 are formed at the head of the cylinder block 6, and these intake and exhaust ports are formed. Inlet and exhaust valves 2 for opening and closing 27 and 28
9 and 30 are provided, and a valve train 31 for opening and closing the intake and exhaust valves 29 and 30 is disposed in the valve train chamber 24.

The valve gear 31 includes a drive timing gear 32 fixed to the crankshaft 13 and a support shaft 3 supported between the joint surfaces of the cylinder block 6 and the crankcase 7.
4, a driven timing gear 33 rotatably supported by the drive timing gear 32 and driven at a half reduction ratio from the drive timing gear 32
And a cam 35 integrally connected to one end of the driven timing gear 33,
A pair of cam followers 37 and 38 supported on a cam follower shaft 36 provided on the cylinder block 6 and a rocker shaft 39 provided on the head of the cylinder block 6 have one ends of the intake and exhaust valves 29 and 30, respectively. And a pair of rocker arms 40 and 41 abutting against the valve head of the cam follower 3 and the other ends of the rocker arms 40 and 41.
A pair of push rods 4 that connect the respective 7, 38
2, 43, and valve springs 44, 45 for urging the intake and exhaust valves 29, 30 in the valve closing direction, respectively. The intake valve 29 is opened during the intake stroke of the piston 8, and the exhaust valve 30 is opened during the exhaust stroke. Can be opened.

The oil reservoir 22 and the crank chamber 23 are communicated with each other through a through hole 46 formed in the crank shaft 13. At this time, the opening of the through hole 46 to the oil reservoir 22 is disposed at the center of the chamber 22, and the storage amount of the lubricating oil O in the chamber 22 is maintained regardless of the inclination or the inverted state of the engine E. The opening is set so as not to sink in the oil.

As shown in FIGS. 2 and 7, on the lower surface of the crankcase 7, a valve chamber 47 connected to the valve operating chamber 24 is formed.
3 communicates with the bottom. The valve chamber 47 is provided with a one-way valve 49 as a control valve for opening and closing the valve hole 48. The one-way valve 49 responds to pressure pulsation of the crank chamber 23, and closes the valve hole 48 when the pressure is reduced. It is designed to open it when boosting.

On the lower surface of the crankcase 7, a U-shaped oil return chamber 50 surrounding the valve chamber 47 is formed as shown in FIG. The oil return chamber 50 communicates with the bottom of the valve operating chamber 24 via a pair of orifices 51 arranged as far away from each other as possible, and also communicates with the oil reservoir 22 via a pair of through holes 46. The overall sectional area of the through hole 46 is the orifice 51
Is set sufficiently larger than the total cross-sectional area.

The valve chamber 47 and the oil return chamber 50 are formed by closing a recess formed on the lower surface of the crankcase 7 with a bottom plate 53, and the bottom plate 53 is formed by the stud bolt 19 and the nut 20. Fastened together with the crankcase 7.

The upper part of the valve operating chamber 24 communicates with the inside of the air cleaner 4 via a rubber breather tube 54 attached to one side wall of the head cover 26 so as to penetrate therethrough. At this time, the valve train chamber 24 of the breather tube 54
The open end is disposed so as to protrude into the valve chamber 24 by a predetermined length. Therefore, in any operating posture of the engine E, it is possible to prevent the oil that somewhat accumulates in the valve train chamber 24 from flowing out to the breather tube 54.

As shown in FIGS. 2, 8 and 9, the head cover 26 has an outer cover 55 fitted around its outer periphery.
Are combined. A flat uppermost chamber 56 is defined between the ceiling walls of the covers 26 and 55, and the chamber 56 is formed with a pair of orifices 57 (preferably at four corners) formed at diagonal positions of the ceiling wall of the head cover 26. Provided with the valve operating chamber 24. The uppermost chamber 56 is provided with one oil passage 58 formed in the cylinder block 6 and the crankcase 7.
Also communicates with the oil return chamber 50 via the. The oil passage 58
It has a cross-sectional area larger than the total cross-sectional area of the pair of orifices 57.

In the above, the orifices 51 and 57, the uppermost chamber 56, the oil passage 58, the oil return chamber 50, and the through hole 46
The return path L for returning the lubricating oil from the valve operating chamber 24 to the oil reservoir 22 is formed. The opening of the return path L to the oil reservoir 22, that is, the outlet end of the through hole 52 is provided with oil. It is arranged at the center of the storage chamber 22 in the front-rear and left-right directions, and below the center in the vertical direction. As a result, as shown in FIGS. 10A and 10B, when the engine E is turned over or in an inverted state in which the valve operating chamber 24 is located below the oil storage chamber 22, the opening portion stores the oil in the oil storage chamber 22. It is designed to be exposed above the oil level.

During the operation of the engine E, the rotation of the crankshaft 13 causes the oil slinger 2 in the oil reservoir 22 to rotate.
5 agitates the lubricating oil O to generate an oil mist, and when the crank chamber 23 is depressurized by the upward movement of the piston 8, the oil mist is passed through the through hole 46 to the crank chamber 2.
3 and lubricates around the crank portion 13a and the piston 8. Next, when the crank chamber 23 is pressurized by the downward movement of the piston 8, the oil mist is supplied together with the blow-by gas generated in the crank chamber 23 from the valve hole 48 to the valve chamber 47 and thus to the valve train chamber 24 by opening the one-way valve 49. Then, oil mist and blow-by gas are separated in the chamber 24. The oil mist lubricates each part of the valve gear 31, and the blow-by gas is supplied to the breather tube 54.
Through the air cleaner 4.

By the way, the pressure in the crank chamber 23 pulsates due to the vertical movement of the piston 5 so as to alternately repeat the positive pressure and the negative pressure. At the time of the positive pressure, the one-way valve 49 opens to release the positive pressure. At the time of negative pressure, the one-way valve 49 closes to prevent reverse flow of the positive pressure from the valve chamber 47, so that the pressure in the crank chamber 23 is maintained in a negative pressure state on average.

On the other hand, the valve operating chamber 24 and the valve chamber 4
Since 7 communicates with the inside of the air cleaner 4 at atmospheric pressure via the breather tube 54, the pressure in both chambers 24 and 47 is substantially atmospheric pressure.

Since the oil reservoir 22 communicates with the crank chamber 23 through the through hole 46, the pressure in the oil reservoir 22 is equal to or slightly higher than that of the crank chamber 23.

The oil return chamber 50 communicates with the oil reservoir chamber 22 through the through hole 52, while the valve train chamber 2 communicates through the orifice 51.
Since it is also in communication with 4, the pressure in the oil return chamber 50 is equal to or slightly higher than that of the oil reservoir chamber 22.

The uppermost chamber 56, while communicating with the oil return chamber 50 through the oil passage 58, since the communicating both the valve operating chamber 24 through the orifice 57, the pressure in the uppermost chamber 56 is an oil return chamber
The pressure is equal to or slightly higher than 50 .

The relationship between the pressures in the respective chambers can be expressed by the following equation.

Pc ≦ Po ≦ Pr ≦ Pt <Pv where Pc: pressure in the crank chamber 23 Po: pressure in the oil reservoir 22 Pr: pressure in the oil return chamber 50 Pt: pressure in the uppermost chamber 56 Pv: valve operating chamber 24 As a result, during the operation of the engine, pressure flows through the following path.

[0037]

[Outside 1]

Therefore, the oil mist sent to the valve operating chamber 24 returns to the oil storage chamber 22 through the above-described pressure path, and the oil liquefied in the valve operating chamber 24 passes through the orifice 51 to the oil return chamber 50 and the oil storage. Reflux to chamber 22. The oil mist and the liquefied oil are returned without any problem regardless of the inclination of the engine E.

In the inverted state of the engine E, the uppermost chamber 56 comes below the valve operating chamber 24, so that the oil liquefied in the valve operating chamber 24 flows into the uppermost chamber 24 through the orifice 57 and returns through the oil passage 58. The liquid is sucked into the chamber 50 and returned to the oil reservoir 22.

As described above, the inclination of the engine E, the inversion, etc.
Regardless of the operating posture, the circulation of the lubricating oil is continuously performed inside the engine E, and a good lubricating state can be always ensured. Therefore, the power trimmer T can withstand operations in all directions. Moreover, since the circulation of the lubricating oil utilizes the pressure pulsation of the crank chamber 23,
No expensive oil pump is required.

After the operation, when the operation of the engine E is stopped and the power trimmer T is left unattended, as shown in FIGS. 10 (A) and 10 (B), the engine E must be turned sideways or placed upside down. However, in such a state, the opening of the return oil passage L connected to the valve operating chamber 24 to the oil reservoir 22, that is, the through hole 52 is provided.
Is exposed above the oil level of the stored lubricating oil O in the oil reservoir 22, the lubricating oil O in the oil reservoir 22 flows back through the recirculating oil passage L to the valve train chamber 24. Intrusion can be prevented. Therefore, leakage of lubricating oil from the valve train chamber 24 to the breather tube 54 can be avoided beforehand.

Referring again to FIG.
The rotor 61 with the cooling blades 60 of the flywheel magneto 59 is fixed to the outer end on the valve train chamber 24 side, and the ignition coil 62 cooperating with the rotor 61 is fixed to the cylinder block 6. A centrifugal clutch 64 is interposed between the rotor 61 and the working machine drive shaft 63. The centrifugal clutch 64 includes a plurality of clutch shoes 65 rotatably supported by the rotor 61, a clutch spring 66 for urging the clutch shoes 65 in a diameter reducing direction, and a clutch shaft 65 that surrounds the clutch shoes 65 and is fixed to the drive shaft 63. When the rotor 61 rotates at or above a predetermined number of revolutions, the clutch shoe 65 expands in diameter and presses against the inner peripheral surface of the clutch drum 67 so that the output torque of the crankshaft 13 is reduced by the drive shaft. 63
To be communicated to.

The engine body 1 has a shroud 69 which covers the head portion and the flywheel magneto 59 and defines a cooling air passage 68 therebetween. A shroud 69 is provided between the centrifugal clutch 64 and the shroud 69. An inlet 68i of the passage 68 is provided in an annular shape, and an outlet 68o is provided in the shroud 69 on the opposite side.

When the rotor 61 rotates, the wind generated by the cooling blades 60 flows through the cooling air passage 68 to cool each part of the engine E.

A known recoil starter 70 capable of cranking the crankshaft 13 is mounted on the outer surface of the crankcase 7 on the oil reservoir 22 side. This starter 7
0 is disposed so as to protrude from the outer surface of the shroud 69 from the viewpoint of its operability.
There is no dead space inside the zero, which can contribute to downsizing of the engine E.

FIGS. 11 to 14 show the one-way valve 49.
Another embodiment of the present invention in which a rotary valve 71 is employed in place of the embodiment will be described. 11 to 13, the rotary valve 71
The cam 3 of the driven timing gear 33 of the valve gear 31
5 has a pair of fan-shaped valve portions 72 protrudingly formed on the side surface opposite to the diameter line and arranged on the diameter line, and a pair of concave portions 73 sandwiched between these valve portions 72 in the circumferential direction. The valve hole 74 is opened and closed by rotation of the driven timing gear 33 so as to face the valve hole 74 formed in the partition wall between the two.

Each of the valve portions 72 and the concave portions 73 are substantially 90
Although the driven timing gear 33 has a central angle of 0 °, the driven timing gear 33
, The closing period and the opening period of the valve hole 74 by each of the valve portions 72 and the concave portions 73 are approximately 180 ° in terms of crank angle.

Further, as shown in FIG. 14, the valve portion 72 and the concave portion 73 are arranged so that the valve hole 74 is opened during the downward stroke of the piston 8 (see FIG. 13) and closed during the upward stroke (see FIG. 11). . A particularly desirable arrangement is to open the valve hole 74 in a range from the middle point P between the bottom and top dead centers of the piston 8 to the descending side 45 ° of the piston 8 at a crank angle, and to open the piston 8 at a crank angle from the middle point P. That is, it is closed within a range up to 45 ° on the rising side.

The other structure is the same as that of the previous embodiment except that the valve chamber 47 is eliminated. In the figure, the same reference numerals are given to the parts corresponding to the previous embodiment.

Thus, the rotary valve 71 is connected to the crankshaft 1.
Since the valve hole 74 is opened and closed mechanically in conjunction with the rotation of the engine 3, the predetermined opening / closing timing for the valve hole 74 does not become out of order even when the engine E is rotating at a high speed, and the inertial effect of the flowing gas. By effectively utilizing the crankcase 23
The oil mist can be efficiently supplied to the valve operating chamber 24 from above, and the average negative pressure state of the crank chamber 23 can be ensured.

The present invention is not limited to the above embodiments, and various design changes can be made without departing from the scope of the gist. For example, the oil reservoir 22 and the crankcase 2
A through hole 46 communicating between the three chambers 3 may be provided in the plain bearing 16 or the partition wall between the two chambers 22 and 23.

[0052]

As described above, according to the present invention, the opening of the recirculation passage to the oil sump is adjusted when the engine is turned sideways or upside down such that the valve operating chamber is located below the oil sump. The valve is positioned so that it is exposed above the oil level of the lubricating oil in the oil reservoir. Therefore, even if the engine is turned over or left standing upside down so that the valve operating chamber is located below the oil reservoir, It is possible to prevent the lubricating oil from flowing back to the return path, thereby easily preventing the leakage of the lubricating oil from the valve operating chamber. Also
What kind of driving posture, such as engine tilt or inverted,
Even so, the circulation of lubricating oil inside the engine is continuous,
A good lubrication state can always be ensured. Moreover, Jun
Is pressure pulsation in the crankcase used for lubrication circulation?
Therefore, an expensive oil pump is not required.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a use state of a valve operating trimmer provided with an engine according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional front view of the engine.

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 a sectional view taken along line 5-5 of FIG. 2;

FIG. 6 is a sectional view taken along line 6-6 in FIG. 2;

FIG. 7 is a sectional view taken along line 7-7 of FIG. 2;

8 is a sectional view taken along line 8-8 in FIG. 2;

FIG. 9 is a sectional view taken along line 9-9 in FIG. 2;

FIG. 10 is a cross-sectional view showing a positional relationship between a stored oil level in an oil reservoir and a return path in an engine in a sideways state (A) and in an inverted state (B).

FIG. 11 shows another embodiment of the present invention, and is a longitudinal sectional view showing the rotary valve in a closed state.

FIG. 12 is a sectional view taken along line 12-12 of FIG. 11;

FIG. 13 is a longitudinal sectional view showing the rotary valve in an open state.

FIG. 14 is a diagram showing opening and closing timings of the rotary valve.

[Explanation of symbols]

 E Engine L Return line O Lubricating oil 1 Engine body 22 Oil reservoir 23 Crank chamber 24 Valve train

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Souhei Honda 1-4-1 Chuo, Wako-shi, Saitama Pref. Honda Technical Research Institute Co., Ltd. (56) References Hirai 3-32106 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F01M 11/00 F01M 1/06

Claims (1)

(57) [Claims] 1. A crank chamber (23) and a valve operating chamber (24).
The engine body (1) having a crank chamber (23) and valve chamber Rutotomoni provided the oil reservoir chamber (22) for storing sequentially supplies lubricating oil (O) to (24), the oil reservoir chamber (22 )
In addition, an oil mist that generates oil mist from the lubricating oil (O)
Accommodating the strike generating means (25), and the valve operating chamber (24) which was approximately atmospheric pressure state, the space between the oil reservoir chamber (22), the valve operating chamber (2
From the bottom of 4) through the orifice (51), the oil reservoir (2)
Be communicated via return path for 2) to return the lubricating oil (L)
In addition , the opening of the return passage (L) to the oil reservoir (22) is positioned such that the valve operating chamber (24) is located below the oil reservoir (22). In this case, the opening is disposed so as to be exposed above the oil level of the lubricating oil (O) in the oil reservoir (22), and the oil reservoir (22) and the crank chamber are arranged.
(23) The through hole (46) is formed on the oil level of the oil reservoir (22).
Through the crank chamber (23) and the valve chamber (24)
Open during pressure rise in the crankcase (23) and close during pressure reduction
Through a control valve (49, 71)
The pressure of (23) is Pc, the pressure of the oil reservoir (22) is Po,
Assuming that the pressure in the valve operating chamber (24) is Pv,
Characterized in that the following equation Pc ≦ Po <Pv and so satisfied, the lubrication system for a four-cycle engine.