JP3159296B2 - 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 of a trimmer or a chain saw.

[0002]

2. Description of the Related Art As a conventional handheld engine, a two-stroke engine capable of exhibiting a lubricating function in any engine operating 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, so if this is adopted for a handheld type, it is necessary to reliably lubricate each part of the engine regardless of the operating posture of the engine.

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 provides a crank chamber for accommodating a crank portion of a crankshaft and for storing lubricating oil, and a valve operating chamber for accommodating a valve operating device. Oil mist generating means for generating oil mist from lubricating oil is provided in the engine body, and the space between the crank chamber and the valve operating chamber is opened above the oil level of the lubricating oil in the crank chamber when the crank chamber is pressurized. while communicating via the control valve to close during decompression, substantially communicates with the atmosphere the upper part of the valve chamber and communicating the bottom of the valve chamber to the crank chamber through an orifice, to the engine body, the valve operating chamber Above
An uppermost chamber that occupies the position is provided, and this uppermost chamber is
To the valve train via
When the pressure in the crank chamber is Pc, the pressure in the valve operating chamber is Pv , and the pressure in the uppermost chamber is Pt , the following equation Pc ≦ Pt <Pv is satisfied when the engine is operating. This is the first feature.

Further, in the present invention, in addition to the first feature, the valve opening period of the rotary valve is set to approximately 180 ° in crank angle, and the valve opening start point is set to the midpoint P between the upper and lower dead centers of the piston. and it sets the range of the descending side 45 ° of the piston in the crank angle from that of the opening end point is set to a range of the piston ascending side 45 ° in crank angle from the midpoint P second
It shall be the feature of.

[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.

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.

In FIG. 2, a carburetor 2 and an exhaust muffler 3 are respectively attached to an engine body 1 of the engine E before and after the engine body 1, 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 utilizes a pressure pulsation of a crank chamber, which will be described later, of the engine E to produce a fuel tank 5.
A diaphragm pump for pumping fuel from the tank and returning excess fuel to the tank 5 is provided, so that fuel can be supplied to the intake port of the engine E in any posture.

3, 4, 6, and 7, the engine body 1 includes a crankcase 6 formed by joining a pair of left and right case halves 6 a and 6 b with bolts, and an upper end surface of the crankcase 6. A head-integrated cylinder block 7 which is bolted. Both case halves 6a, 6
b supports the crankshaft 8 horizontally, and the crankshaft 8
A piston 10 connected to a crank pin of the vehicle through a connecting rod 9 is provided with a cylinder 7 formed in a cylinder block 7.
a is slidably fitted to a.

An intake port 11 and an exhaust port 12 connected to the carburetor 2 and the exhaust muffler 3, respectively, are formed on the top wall of the cylinder 7a.
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 from the side of the crankcase 6 and the cylinder block 7 to the head of 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 gears 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 32 formed in the crankcase 6 surrounds a cylindrical inner chamber 32a in which the crank portion 8a of the crankshaft 8 is disposed, and surrounds the inner chamber 32a from the bottom to both sides in the circumferential direction. Outer chamber 32a having a U-shaped cross section
And a partition 3 between the inner and outer chambers 32a, 32b.
4, the inner and outer chambers 32 at the bottom of the crank chamber 32;
a, 32b are provided with openings 33 for communicating with each other.

Lubricating oil O is stored in the bottom of the crank chamber 32, and its amount is set such that its oil level slightly touches the outer periphery of the crank portion 8a. When the crankshaft 8 rotates, the lubricating oil O is stirred and scattered to form an oil mist. An oil dipper 35 as oil mist generating means is formed at the large end of the connecting rod 9.

As shown in FIGS. 4 and 10, the crank chamber 32 and the valve operating chamber 16 are provided with first and second drilled holes formed in the crank shaft 8 and the crank case 6 above the oil level in the crank chamber 32, respectively. They are communicated with each other via supply oil passages 36 and 37. The valve chamber 16 communicates with the crank chamber 32 through an orifice 38 at the bottom.

A rotary valve 39 is provided between the first and second supply oil passages 36 and 37 as a control valve. The rotary valve 39 includes an arc groove 60 of approximately 180 ° formed on the outer periphery of the journal portion 8b at one end of the crankshaft 8 and a bearing portion 61 of the crankcase 6 supporting the journal portion 8b. The first supply oil passage 36 on the crankshaft 8 side is connected to the arc groove 60, and the second supply oil passage 37 on the crankcase 6 side is connected to the arc hole 60. Is done. Therefore, the arc groove 60 and the valve hole 62 alternately communicate (open) and shut off (close) alternately every time the crankshaft 8 rotates approximately 180 °. Open during the stroke (Fig. 5
(See FIG. 4), and the valve is closed (see FIG. 4) during the ascent stroke. A particularly desirable arrangement is as shown in FIG.
The valve is started to open from the midpoint P between the upper and lower dead centers of the piston 10 to the descending side 45 ° of the piston 10 at a crank angle, and from the midpoint P to the rising side 45 ° of the piston 10 at a crank angle. Is to end the valve opening in the range.

As shown in FIG. 7, the upper part of the valve operating chamber 24 is
It communicates with the inside of the air cleaner 4 via a rubber breather tube 42 attached to one side wall of the head cover 21 so as to penetrate the head cover 21. At this time, the open end of the breather tube 42 to the valve operating chamber 16 is arranged so as to protrude into the valve operating chamber 16 by a predetermined length. Therefore, engine E
In any operating posture, it is possible to prevent oil that has accumulated in the valve operating chamber 16 from flowing out to the breather tube 42 at all.

As shown in FIGS. 3, 8 and 9, the head cover 21 has an outer cover 63 fitted around its outer periphery.
Are combined. A flat uppermost chamber 64 is defined between the ceiling walls of the covers 21 and 63, and the chamber 64 is formed with a pair of orifices 65 (preferably at four corners) formed at diagonal positions of the ceiling wall of the head cover 21. Provided with the valve operating chamber 16. The uppermost chamber 64 communicates with the inner chamber 32 a of the crank chamber 32 through a series of return oil passages 66 formed in the cylinder block 6 and the crankcase 6. The return oil passage 66 has a cross-sectional area larger than the total cross-sectional area of the pair of orifices 65.

During operation of the engine E, the oil dipper 35 at the large end of the connecting rod 9 moves up and down between the outer chambers 32a and 32b of the crank chamber 32 through the opening 33 as the crankshaft 8 rotates. By oscillating, the lubricating oil O is stirred and scattered, and an oil mist is generated in the crank chamber 22. This oil mist is first applied to the crank section 8
a after lubricating around the piston 10 and the rotary valve 3
When the valve 9 opens, the pressure in the crank chamber 32 increases,
Then, the oil mist and the blow-by gas are supplied to the valve operating chamber 16 together with the blow-by gas through the second supply oil passages 36 and 37, where the oil mist and the blow-by gas are separated. The oil mist lubricates the components of the valve train 15, and the blow-by gas is discharged to the air cleaner 4 through the breather tube.

By the way, the pressure in the crank chamber 32 pulsates as the piston 10 moves up and down so as to alternately repeat positive pressure and negative pressure. When the positive pressure is generated, the positive pressure is reduced by opening the rotary valve 39. The oil is discharged to the valve operating chamber 16 via the first and second supply oil passages 36 and 37, and when a negative pressure is generated, the rotary valve 3 is released.
Since the reverse flow of the positive pressure from the valve operating chamber 16 is prevented by closing the valve 9, the pressure in the crank chamber 32 is maintained in a negative pressure state on average.

On the other hand, the valve train 16 has a breather tube 42.
, The pressure in the valve operating chamber 16 is substantially atmospheric pressure.

The uppermost chamber 64 communicates with the crank chamber 32 via the recirculating oil passage 16 and also communicates with the valve operating chamber 16 via the orifice 65. Therefore, the pressure in the uppermost chamber 64 is the same as that of the crank chamber 32. Alternatively, the pressure becomes slightly lower.

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

Pc ≦ Pt <Pv As a result, during the operation of the engine E, a pressure flow is generated in the following path.

[0025]

[Outside 1]

Therefore, the valve operating chamber 1 is moved from the crank chamber 32 to the valve operating chamber 1.
The oil mist sent to 6 returns to the crank chamber 32 again through the above-mentioned path. The oil liquefied in the valve chamber 16 returns to the crank chamber 32 through the orifice 38. The oil mist and the liquefied oil are circulated without any problem regardless of the inclination of the engine E.

When the engine E is turned over or turned over as shown in FIGS. 12 and 13 during operation of the engine E, much of the lubricating oil O in the crank chamber 32 flows to the closed end side of the outer chamber 32b, Since the amount of lubricating oil O remaining in 32a is small, it is possible to prevent the piston 10 from being immersed in oil, and to prevent oil from entering the combustion chamber.

In such an operation state of the engine E in a sideways and inverted posture, the oil liquefied in the valve operating chamber 16 flows out to the uppermost chamber 64 through the orifice 65, but the above-mentioned pressure relationship between the respective chambers is maintained. Therefore, the oil accumulated in the uppermost chamber 64 passes through the recirculating oil passage 66 so that the inner chamber 3 of the crank chamber 32
2a.

On the other hand, the oil dipper 35 of the connecting rod 9
Can not stir the lubricating oil O in such a case,
The oil returned from the return oil passage 66 to the inner chamber 32a hits the crank portion 8a of the crankshaft 8 and the piston 10 and is scattered again to become oil mist, so that there is no hindrance to the lubrication of each part of the engine E.

As described above, the engine E can be tilted, inverted, 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. In addition, since the pressure pulsation of the crank chamber 23 is utilized for the circulation of the lubricating oil by the rotary valve 39, an expensive oil pump is not required.

In particular, the rotary valve 39 is effective when applied to a high-speed engine because the opening and closing timing does not change even when the engine E is rotating at high speed. With this setting, the oil mist can be circulated and the pressure in the crank chamber 32 can be reduced more effectively by using the inertia effect of the gas.

Referring again to FIG.
A recoil starter 43 capable of cranking the crankshaft 8 is mounted on the outer surface opposite to the valve chamber 16. At the outer end of the crankshaft 8 on the valve operating chamber 16 side, a rotor 46 with a cooling blade 45 of a flywheel magneto 44 is fixed, and an ignition coil 47 cooperating with the rotor 46 is fixed to the cylinder block 6. Is done. A centrifugal clutch 49 is interposed between the rotor 46 and the working machine drive shaft 48. The centrifugal clutch 49 is mounted on the rotor 4
6. A plurality of clutch shoes 50 supported so as to be able to expand in diameter.
And a clutch spring 52 for biasing the clutch shoe 50 in the radial direction, and a clutch drum 52 that surrounds the clutch shoe 50 and is fixed to the drive shaft 48. When the rotor 46 rotates at a predetermined rotation speed or more, The clutch shoe 50 expands in diameter and presses against the inner peripheral surface of the clutch drum 52, and
Is transmitted to the drive shaft 48.

The engine body 1 is provided with a shroud 53 which covers the head portion and the flywheel magneto 44 and defines a cooling air passage 54 therebetween. The shroud 53 is provided between the centrifugal clutch 49 and the shroud 53. An inlet 54a of the passage 54 is provided in an annular shape, and an outlet 54b is provided in the shroud 53 on the opposite side.

When the rotor 46 rotates, the wind generated by the cooling blades 45 flows through the cooling air passage 54 to cool each part of the engine E.

The present invention is not limited to the above-described embodiment, and various design changes can be made without departing from the scope of the gist. For example, instead of the rotary valve 39,
A one-way valve, such as a reed valve, which opens and closes in response to the elevation and decompression of the crank chamber 32 may be provided between the crank chamber 32 and the valve chamber 16.

[0036]

As described above, according to the first aspect of the present invention, a crank chamber for accommodating a crank portion of a crankshaft and storing lubricating oil and a valve operating chamber for accommodating a valve operating device are formed. Oil mist generating means for generating oil mist from lubricating oil is provided in the engine body, and oil mist generating means for generating oil mist from lubricating oil is provided. At the same time, the upper part of the valve chamber is substantially communicated with the atmosphere, and the bottom of the valve chamber is communicated with the crank chamber through an orifice. Assuming that the pressure in the valve chamber is Pv, the following equation is obtained when the engine is operating: Pc <Pv
Therefore, the oil mist is circulated between the crank chamber and the valve operating chamber by utilizing the relationship between the pressures of the two chambers in any inclined state of the engine, and the oil liquefied in the valve operating chamber is also used in the crank chamber. And a good lubrication state can be ensured. Moreover, since an expensive oil pump is not required, it is advantageous in terms of cost.

[0037] or engine body, the uppermost portion room occupying a position above the valve chamber is provided, communicated with the uppermost portion room in a valve chamber through the orifice, communicating the crank chamber via a reflux oil passage When the pressure in the uppermost chamber is Pt, the following equation Pc ≦ Pt <Pv is satisfied during operation of the engine. Therefore, even when the engine is turned sideways or in an inverted state, the oil mist is circulated as well as circulated. The oil accumulated in the uppermost chamber can be reliably returned to the crank chamber, and a good lubrication state can be ensured.

According to a second feature of the present invention, the opening period of the rotary valve is set to approximately 180 ° in terms of crank angle, and the valve opening start point is set between the middle point between the top and bottom dead centers of the piston. Angle is set in the range of 45 ° on the descending side of the piston, and the valve opening end point is set in the range of 45 ° on the ascending side of the piston in crank angle from the middle point P. it is possible to effectively perform the positive pressure discharge of the valve chamber from the crank chamber by utilizing the inertia effect, thus ensuring an average negative pressure state of the transport and the crank chamber of the oil mist that Do more reliably.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a use state of a power trimmer including a four-cycle engine according to an embodiment of the present invention.

FIG. 2 is a side view of the engine.

FIG. 3 is a longitudinal sectional front view of the engine.

FIG. 4 is an enlarged view of a main part of FIG. 3;

FIG. 5 is a sectional view corresponding to FIG. 4, showing different operating states of the rotary valve.

FIG. 6 is a sectional view taken along line 6-6 in FIG. 3;

FIG. 7 is a sectional view taken along line 7-7 of FIG. 3;

8 is a sectional view taken along line 8-8 in FIG. 3;

9 is a sectional view taken along line 9-9 in FIG. 3;

FIG. 10 is a sectional view taken along line 10-10 of FIG. 4;

FIG. 11 is a diagram showing the opening / closing timing of a rotary valve.

FIG. 12 is a sectional view showing a state of lubricating oil in a crank chamber when the engine is turned sideways.

FIG. 13 is a sectional view showing the state of lubricating oil in the crank chamber when the engine is inverted.

[Explanation of symbols]

E Engine O Lubricating oil 1 Engine body 6 Crankcase 8 Crankshaft 8a Crank part 15 Valve train 16 Valve train 32 Crank chamber 32a Inner chamber 32b Outer chamber 34 Partition wall 35 Oil dipper as oil mist generation means 38 Orifice 64 Top chamber 65 Orifice 66 Return oil passage

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takanori Norikawa 1-4-1 Chuo, Wako-shi, Saitama Prefecture Honda R & D Co., Ltd. (56) References Japanese Utility Model No. 5-14515 (JP, U) ( 58) Surveyed field (Int.Cl. ⁷ , DB name) F01M 9/06 F01M 9/12 F01M 11/00 F01M 11/06

Claims (2)

(57) [Claims] Crank part (8a) of a crankshaft (8)
, A crank chamber (32) for storing lubricating oil (O), and a valve chamber (1) for storing a valve gear (15).
6) is provided in the engine body (1), and the crankcase (3) is provided.
2) An oil mist generating means (35) for generating an oil mist from the lubricating oil (O) is provided in the crank chamber (32).
And a control valve (39) that opens and closes when the pressure in the crank chamber (32) is increased and depressurized above the level of the lubricating oil (O) in the crank chamber (32). communicates with the substantially atmospheric the upper valve chamber (16), also communicates the bottom of the valve chamber (16) in an orifice (38) via a crank chamber (32), the engine body (1) ,
The uppermost chamber (64) occupying the position above the valve chamber (16)
And the uppermost chamber (16) is connected through an orifice (65).
To communicate with the valve operating chamber (16),
6), the pressure in the crank chamber (32) is Pc, the pressure in the valve operating chamber (16) is Pv ,
A lubricating device for a four-stroke engine, characterized in that when the pressure in the uppermost chamber (64) is Pt , the following equation is satisfied during operation of the engine: Pc ≦ Pt <Pv . 2. The method according to claim 1 , wherein the opening period of the rotary valve (39) is approximately 180 degrees in crank angle.
And the starting point of the valve opening is set in a range of 45 ° on the descending side of the piston (8) at a crank angle from the midpoint P between the top and bottom dead centers of the piston (8), and the valve closing end point. From the middle point P at the crank angle to the rising side 4 of the piston (10).
Characterized by being set in a range of 5 °, lubrication equipment four-cycle engine.