JP2001263034A - Handheld four-stroke engine - Google Patents

Abstract

(57) [Problem] To provide a hand-held four-stroke engine capable of reliably lubricating a valve operating mechanism in any operating posture of an engine while enabling a compact and lightweight engine body. . SOLUTION: An intake valve 1 is provided on a side wall of a cylinder block 7.
8i and the exhaust valve 18e, and these valves are connected to the crankshaft 1
The oil tank 13 is formed on one side wall of the cylinder block 7 in the four-stroke engine provided with the valve mechanism 23 that opens and closes in conjunction with the oil tank 13.
Contains oil mist generating means 36 to 41 for generating oil mist from the stored oil O and the valve train 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a hand-held four-stroke engine, which is suitable mainly for a trimmer or an engine serving as a power source of a portable work machine.

[0002]

2. Description of the Related Art As a hand-held four-stroke engine, an oil mist generated from oil in a sump is circulated inside the engine in order to lubricate the inside of the engine in any operating posture of the engine. No. 10-28801.

[0003]

However, in the lubricating apparatus disclosed in the above publication, the oil mist circulation path starts from the oil tank, moves to the crank chamber and the valve operating chamber, and returns to the oil tank. Long and complex. If the circulation path of the oil mist is long and complicated as described above, the size of the engine body forming the oil mist increases, and it is difficult to reduce the weight. Weight reduction is one of the important issues in improving workability, especially for a hand-held four-stroke engine.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it has been made possible to reliably lubricate a valve operating mechanism in any operating posture of an engine while enabling a compact and lightweight engine body. Another object of the present invention is to provide a hand-held four-stroke engine.

[0005]

In order to achieve the above object, the present invention comprises a crankcase having a crank chamber for accommodating a crankshaft, and a cylinder block having a cylinder bore. , Intake and exhaust valves, and a hand-held four-stroke engine equipped with a valve mechanism that opens and closes these valves in conjunction with the crankshaft. Oil is stored on one side wall from the crankcase to the cylinder block. A first feature is that an oil tank is formed, and the oil tank houses oil mist generating means for generating oil mist from stored oil and the valve mechanism.

The oil mist generating means corresponds to the oil slinger 36 to 41 in an embodiment of the present invention described later.

According to the first feature, since the inside of the oil tank can be filled with the oil mist generated by the oil mist generating means, each part of the valve mechanism provided in the oil tank is used as an engine. The lubrication can be surely performed by the above oil mist in any operation posture. Therefore, there is no need to provide a special oil supply oil passage for lubrication of the valve mechanism in the engine body, and the size and weight of the engine can be reduced. In addition, since the oil tank extends from the crankcase to the cylinder block on one side wall, there is no need to provide an oil reservoir at the lower part of the crankcase, so that the overall height of the engine can be kept low and the size of the engine can be further reduced. .

The present invention, in addition to the first feature, further comprises a forward path and a return path communicating between the oil tank and the crank chamber above the stored oil in the oil tank, and the return path includes a pressure pulsation generated in the crank chamber. A second feature is that a valve means for guiding the positive pressure component to the oil tank side is provided.

The valve means corresponds to a one-way valve 51 in an embodiment of the present invention described later.

According to the second feature, the oil mist generated in the oil tank is circulated between the oil tank and the crank chamber by utilizing the pressure pulsation of the crank chamber. , Can lubricate the crankshaft and the piston. In addition, since it is sufficient that the oil mist circulates between the oil tank and the crank chamber, the forward and return paths connecting the two chambers can be made relatively short and simple. The weight can be reduced.

Further, in addition to the first or second feature, the present invention further comprises a breather chamber communicating with the return path between the valve means and the oil tank, and the breather chamber communicates on one side with an air cleaner of an intake system, and on the other hand. That the orifice communicated with the suction chamber communicating with the oil tank in
The feature of.

According to the third feature, the blow-by gas generated in the crank chamber moves to the breather chamber together with the oil mist to be separated into gas and liquid, the blow-by gas is discharged to the air cleaner, and the liquefied oil passes through the orifice. To the suction chamber and return to the low-pressure oil tank.

[0013]

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 the hand-held type four-stroke engine of the present invention, FIG. 2 is a longitudinal side view of the four-stroke engine, FIG. 3 is a sectional view taken along line 3-3 of FIG. Is a sectional view taken along line 4-4 in FIG. 3, and FIG. 5 is a sectional view taken along line 5-5 in FIG.
FIG. 6 is a sectional view taken along line 6-6 of FIG.

As shown in FIG. 1, the hand-held four-stroke engine E is mounted on a drive unit of the power trimmer T as a power source, for example. Since the power trimmer T is used with the cutter C oriented in various directions depending on the working state, the engine E is also tilted or inverted upside down each time, and the driving posture is not constant.

2 and 3, a carburetor 2 and an exhaust muffler 3 are attached to the front and rear of the engine body 1 of the hand-held type four-cycle engine E, respectively.
An air cleaner 4 is attached to the inlet of the carburetor 2 at the intake path.
A fuel tank 5 made of synthetic resin is attached to the lower surface of the engine body 1.

The engine body 1 comprises a crankcase 6 having a crank chamber 6a, a cylinder block 7 having one cylinder bore 7a, and a cylinder head 8 having a combustion chamber 8a. Are formed with a large number of cooling fins 11.

Crankshaft 1 housed in crankcase 6a
Numeral 2 is rotatably supported on both left and right side walls of the crankcase 6 via ball bearings 14 and 14 ', and is connected via a connecting rod 16 to a piston 15 fitted in the cylinder bore 7a.

From the crankcase 6 to the cylinder block 7
An oil tank 13 is continuously provided on the left side wall. The oil tank 13 has a tank inner half 13 a integrally connected to the crankcase 6 and the cylinder block 7.
And an oil tank outer half 13b bolted to the oil tank 13.
Of the crankshaft 12 penetrates and projects to the outside.
The oil seal 17 closely contacting the outer peripheral surface of the tank is mounted on the tank outer half 13b.

A flywheel 24 having a number of cooling blades 25 is fixed to the left end of the crankshaft 12 projecting out of the oil tank 13, and a recoil starter 26 is disposed outside the flywheel 24. .

An oil seal 17 'is mounted on the right side wall of the crankcase 6 so as to be adjacent to the outside of the bearing 14', and is driven to the right end of the crankshaft 12 which penetrates the oil seal 17 'and projects to the outside. A plate 27 is fixed, and a plurality of centrifugal shoes 28 (only one is shown in the figure) are pivotally supported on the driving plate 27 in a swingable manner. This centrifugal shoe 28
Constitutes a centrifugal clutch 31 together with a clutch drum 30 connected to a drive shaft 29 for driving the cutter C. When the rotation speed of the crankshaft 12 exceeds a predetermined value, the centrifugal shoe 28 is driven by its own centrifugal force. By pressing against the inner peripheral wall of the clutch drum 30, the output torque of the crankshaft 12 is transmitted to the drive shaft 29.

Cylinder block 7 and cylinder head 8
Has an overhanging portion 19 projecting to the same side as the oil tank 13, and a lower portion of the overhanging portion 19 forms a part of an upper wall of the tank inner half body 13a. In the overhang portion 19, a combustion chamber 8a is formed in the cylinder head 8, and an intake port 9i and an exhaust port 9e connected to the combustion chamber 8a are formed in the cylinder block 7.
Formed. An ignition plug 10 that makes the combustion chamber 8 a an electrode is screwed to the cylinder head 8.

On the overhang portion 19, that is, on the upper wall of the tank inner half 13a, an intake valve 18i and an exhaust valve 18e for opening and closing the intake port 9i and the exhaust port 9e such that each valve head projects into the oil tank 13. Mounted vertically. A valve mechanism 23 for opening and closing the intake valve 18i and the exhaust valve 18e is arranged in the oil tank 13.

The valve mechanism 23 is rotatably supported by a drive gear 32 fixed to the crankshaft 12 and a pair of support shafts 33 and 34 provided in the oil tank 13 above the crankshaft 12. A pair of driven gears 36, 37 driven by the gear 32 at a reduction ratio of 吸 気, an intake cam 21 i and an exhaust cam 21 e formed integrally with the driven gears 36, 37, and the oil tank 13 oscillate. The intake cam 21i and the intake valve 18i are movably supported by the shaft.
Intake cam follower 22i and exhaust cam 2
It comprises an exhaust cam follower 22e interposed between 1e and the exhaust valve 18e, and valve springs 20i and 20e for urging the intake valve 18i and the exhaust valve 18e in the closing direction, respectively. Thus, the engine E is configured as an SV type.

The driven gear 36 and the intake cam 21i, and the driven gear 37 and the exhaust cam 21e are largely axially separated from each other so as to be close to the left and right inner side walls of the oil tank 13, respectively. Exhaust cam 2
1e, gear-type oil slinger 39,
40 are integrally formed.

The oil tank 13 has a crankshaft 1
A further support shaft 35 is provided below the drive shaft 2. A driven gear 38 driven by the drive gear 32 and a blade-type oil slinger 41 integral with the driven shaft 38 are rotatably supported on the support shaft 35. Is done. The driven gear 38 and the oil slinger 41 are axially separated from each other so as to be close to the left and right inner side walls of the oil tank 13, respectively.

A predetermined amount of lubricating oil O is stored in the oil tank 13, and any of the three driven gears 36 to 38 and the oil slinger 39 to 41 can be used in any operating posture of the engine E. A part is immersed in the stored oil O, and the rotation causes the stored oil O to be scattered to generate an oil mist. Therefore, the three driven gears 36 to 38 also function as oil slinger, and eventually the three support shafts 33, 3
A pair of oil slinger 36, 39; 37, 40;

Next, the oil tank 13 and the crank chamber 6
Fig. 2 shows the oil mist circulation path between
This will be described with reference to FIGS.

Between the oil tank 13 and the crank chamber 6a, a forward path 45 and a return path 46 for circulating the oil mist generated in the oil tank 13 between the two chambers 13 and 6a are provided. The outgoing path 45 corresponds to the crankshaft 12.
The return passage 46 is formed with a valve hole 47 formed in the bottom wall of the crankcase 6 and a valve communicating with the crank chamber 6a through the valve hole 47. It comprises a chamber 48 and a first return pipe 49 communicating between the valve chamber 48 and the oil tank 13.
The valve chamber 48 is provided with a one-way valve 51 composed of a reed valve for opening and closing the valve hole 47. When a positive pressure is generated in the crank chamber 6a as the piston 15 moves up and down, the valve opens and the valve hole 47 is opened.
Is opened to close the valve hole 47 when a negative pressure is generated.

The open ends of the forward passage 45 and the first return pipe 49 to the oil tank 13 are arranged so as to always be exposed from the liquid level of the stored oil O regardless of the operating posture of the engine E.

On one side of the valve chamber 48, a breather chamber 53 communicating with the valve chamber 48 via a communication hole 52 is provided. The breather chamber 53 is partitioned by a barrier 54 into a plurality of expansion chambers 53a and 53b (two chambers in the figure). These expansion chambers 53a and 53b are connected to the throttle passages 5 on both sides of the barrier 54.
The expansion chamber 53 b communicating with each other via the communication holes 5 and 55, and farthest from the communication hole 52, is connected to the inside of the air cleaner 4 via the breather pipe 56.

A horizontal flat chamber 57a is provided directly below the breather chamber 53, and the horizontal flat chamber 57a is provided on one side of the oil tank 13 of the breather chamber 53.
A vertical flat chamber 57b rising from one end is provided, and the suction chamber 57 is constituted by the flat chambers 57a and 57b. The horizontal flat chamber 57a is communicated with the breather chamber 53 through orifices 58, 58,... Arranged in several places, and the vertical flat chamber 57b is also connected to the orifices 58, 58 near the ceiling of the breather chamber 53. Are communicated with the breather chamber 53 through.

The suction chamber 57 communicates with the inside of the oil tank 13 via a second return pipe 59. At this time, the opening end of the second return pipe 59 to the oil tank 13 is connected to the first return pipe 4.
As in the case of 9, the valve chamber 48 and the breather chamber 53 which are arranged so as to be always exposed from the liquid level of the stored oil O in any operating posture of the engine E are integrally formed at the lower part of the crankcase 6. A horizontal flat chamber 57a is defined between the wall 60 and a gasket 61 joined to the lower end surface thereof. The flat chamber 57a in the horizontal direction includes a gasket 61 and a bottom plate 62 connected to the surrounding wall 60 with the peripheral edge thereof interposed therebetween. Is defined between The vertical flat chamber 57b is formed in a partition wall between the breather chamber 63 and the oil tank 13.

Referring again to FIG. 2, the engine body 1 includes
An engine cover 65 covering this is fixed, and the recoil starter 26 is supported by the cover. An air intake 66 is provided in the engine cover 65 around the recoil starter 26 so as to face the cooling blades 25 of the flywheel 24.

Next, the operation of this embodiment will be described.

When the drive gear 32 rotates together with the crankshaft 12 during operation of the engine E, the three sets of oil slinger 36, 39; 37, 40 supported on the three support shafts 33, 34, 35 are thereby provided. 38, 41 rotate simultaneously,
Regardless of the operating posture of the engine, any one of the oil slinger scatters the stored oil O to reliably generate the oil mist, so that the oil tank 13 can always be filled with the oil mist. Such an oil tank 1
3 is provided with a valve mechanism 23, and the driven gears 36, 3
The cam follower 22 cooperates with the valve springs 20i and 20e by the intake cam 21i and the exhaust cam 21e which rotate together with
Since the intake valve 18i and the exhaust valve 18e are driven to open and close as needed via the i and 22e, each part of the valve mechanism 23 can be reliably lubricated by the oil mist. Therefore, there is no need to provide a special oil supply oil passage for lubrication of the valve train 23 in the engine body 1, and the size and weight of the engine E can be reduced. Oil tank 1
3 is provided on one side wall from the crankcase 6 to the cylinder block 7, so that there is no need to provide an oil reservoir at the lower part of the crankcase 6, and the overall height of the engine E is kept low to further reduce its size. Can be.

On the other hand, in the crank chamber 6a, a negative pressure and a positive pressure are generated alternately as the piston 15 moves up and down, and when the negative pressure is generated, the one-way valve 51 closes to close the valve hole 47. At the same time, the oil mist in the oil tank 13 is sucked into the crank chamber 6a through the through hole of the crankshaft 12, that is, the outward path 45, whereby the crankshaft 12 and the piston 15 can be lubricated. At this time, the pressure in the oil tank 13 is reduced by suction of the oil mist into the crank chamber 6a.

Next, when a positive pressure is generated, the one-way valve 51 opens to open the valve hole 47, so that the oil mist in the crank chamber 6a returns to the return path 46, that is, the valve hole 47, the valve chamber 48 and the first return pipe. It is returned into the low pressure oil tank 13 through 49.
Thus, it is sufficient that the oil mist circulates between the oil tank 13 and the crank chamber 6a.
The outgoing route 45 and the return route 46 connecting between 3, 6a are relatively short,
In addition, simplification can be achieved, which can contribute to downsizing and weight reduction of the engine body 1.

During this time, the blow-by gas generated in the crank chamber 6a is transferred to the valve chamber 48 together with the oil mist, and further to the breather chamber 53 through the communication hole 52, where the first and second blow-by gases are discharged.
Gas and liquid are separated while passing through the expansion chambers 53a and 53b, and only the blow-by gas is discharged from the breather pipe 56 to the air cleaner 4.

The oil separated and liquefied in the breather chamber 53 passes through the orifices 58, 58,.
Flows into. First suction chamber 57 and second suction chamber 5
7 is a low-pressure oil tank 13 via a second return pipe 59.
Since the oil communicates with the inside, the oil that has moved to the suction chamber 57 is sucked into the oil tank 13 through the second return pipe 59. In particular, as described above, the suction chamber 57 is composed of a horizontal flat chamber 57a and a vertical flat chamber 57b rising from one end thereof, and is connected to the breather chamber 53 through orifices 58, 58, respectively. Because of the communication, the oil accumulated in the breather chamber 53 is sucked out not only when the engine E with the horizontal flat chamber 57a downward but also when the engine E with the vertical flat chamber 57b downward is turned over. The oil tank 13
Can be returned to.

Further, the flywheel 24 with the cooling blade 25 driven by the crankshaft 12 is disposed adjacent to the outside of the oil tank 13 so that the cooling blade 25
The rotation of the air intake 66 of the engine cover 65
The cooling air sucked from the oil tank 13 is immediately applied to the oil tank 13 to effectively cool the stored oil O and the oil mist inside the oil tank 13 so that the lubrication and cooling of each part can be performed well.

Further, since the valve mechanism 23 and the centrifugal clutch 31 are respectively connected to both ends of the crankshaft 12 with the engine body 1 interposed therebetween, during operation of the engine E,
Since the load from the valve train 23 and the drive shaft 29 is distributed and acts on both ends of the crankshaft 12, the crankshaft 12 and the bearings 14 and 14 'supporting the crankshaft 12 are supported.
It is possible to avoid the concentration of the load on the substrate and improve their durability.

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 one-way valve 61, a rotary valve that operates so as to conduct the oil feed conduit 60 when the piston 15 descends and shut off when the piston 15 rises in conjunction with the crankshaft 12 may be provided.

[0044]

As described above, according to the first feature of the present invention, a crankcase having a crank chamber for accommodating a crankshaft and a cylinder block having a cylinder bore are provided. A hand-held four-stroke engine provided with an intake valve, an exhaust valve, and a valve operating mechanism for opening and closing these valves in conjunction with a crankshaft, wherein oil is stored on one side wall from a crankcase to a cylinder block. A tank is formed, and the oil tank contains oil mist generating means for generating oil mist from the stored oil and the valve operating mechanism. Therefore, each part of the valve operating mechanism is filled with the oil mist in the oil tank. Can be reliably lubricated in any operating posture of the engine. Therefore, there is no need to provide a special oil supply oil passage for lubrication of the valve mechanism in the engine body, and the size and weight of the engine can be reduced. In addition, since the oil tank extends from the crankcase to the cylinder block on one side wall, there is no need to provide an oil reservoir at the lower part of the crankcase, so that the overall height of the engine can be kept low and the size of the engine can be further reduced. .

According to the second feature of the present invention, a forward path and a return path communicating between the oil tank and the crank chamber are provided above the stored oil in the oil tank, and the positive path of pressure pulsation generated in the crank chamber is provided in the return path. Since the valve means for guiding the pressure component to the oil tank side is provided, the oil mist generated in the oil tank is circulated between the oil tank and the crank chamber using the pressure pulsation of the crank chamber, and any operation of the engine is performed. Even in the posture, the crankshaft and the piston can be lubricated. In addition, since it is sufficient that the oil mist circulates between the oil tank and the crank chamber, the forward and return paths connecting the two chambers can be made relatively short and simple. The weight can be reduced.

According to a third aspect of the present invention, a breather chamber communicates with the return path between the valve means and the oil tank, and the breather chamber communicates on one side with an air cleaner of an intake system and on the other side with an oil tank. The blow-by gas generated in the crank chamber is transferred to the breather chamber together with the oil mist and separated into gas and liquid. The blow-by gas is discharged to the air cleaner, and the oil passes through the orifice and the suction chamber. It can be returned to the low pressure oil tank.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of use of a handheld four-stroke engine of the present invention.

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

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

FIG. 4 is a sectional view taken along line 4-4 of FIG. 3;

FIG. 5 is a sectional view taken along line 5-5 of FIG. 4;

FIG. 6 is a sectional view taken along line 6-6 in FIG. 5;

[Explanation of symbols]

E ···· Engine O · · · · · Oil stored 1 · · · · · Engine body 4 · · · · · · Air cleaner 6 · · · · · · Crankcase 6a · · · · · Crankcase 7 · · · ·.・ Cylinder block 7a ・ ・ ・ ・ ・ ・ Cylinder bore 8 ・ ・ ・ ・ ・ ・ Cylinder head 12 ・ ・ ・ ・ ・ ・ Crank shaft 13 ・ ・ ・ ・ ・ ・ Oil tank 18i ・ ・ ・ Intake valve 18e ・ ・ ・ Exhaust valve 23 ・ ・ ・ ・ ・ ・ Valve Mechanisms 36 to 41 Oil mist generating means (oil slinger) 45 Outward path 46 Return path 51 Valve means (one-way valve) 53 Breather chamber 57・ Suction chamber 58 ・ ・ ・ ・ orifice

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) F01M 1/16 F01M 1/16 E 9/06 9/06 C 9/10 9/10 A 13/04 13 / 04 A (72) Inventor Ikuo Watanabe 1-4-1 Chuo, Wako-shi, Saitama F-Term in Honda R & D Co., Ltd. (Reference) 3G013 AA03 AA04 AB03 BA04 BB12 BC11 BD24 BD27 BD46 BD47 CA00 CA01 3G015 AA03 AA04 AB03 BC02 BC03 BD24 BE03 BF05 BF08 CA06 CA07 EA14 EA25 3G016 AA05 AA19 BA21 BA30 BA46 BA48 BA49 BA50 CA29 GA02

Claims (3)

[Claims] 1. A crankcase (6) having a crank chamber (6a) for accommodating a crankshaft (12) and a cylinder block (7) having a cylinder bore (7a), and a side wall of the cylinder block (7). The intake valve (18i) and the exhaust valve (18e), and a valve mechanism (2) for opening and closing these valves in conjunction with the crankshaft (12).
An oil tank (13) for storing oil (O) is provided on one side wall of a hand-held type four-stroke engine provided with (3) from a crankcase (6) to a cylinder block (7). Oil tank (1
3) A handheld four-stroke engine characterized by containing oil mist generating means (36 to 41) for generating oil mist from stored oil (O) and the valve mechanism (23). 2. The hand-held type four-stroke engine according to claim 1, wherein an outward path (45) communicating between the oil tank (13) and the crank chamber (6a) above the stored oil (O) in the oil tank (13). And a return path (46), and the return path (46) is provided with valve means (51) for guiding the positive pressure component of the pressure pulsation generated in the crank chamber (6a) to the oil tank (13) side. , Handheld four-stroke engine. 3. The breather chamber (53) in the return path (46) between the valve means (51) and the oil tank (13) in the hand-held four-stroke engine according to claim 1 or 2.
The breather chamber (53) is communicated on the one hand with the air cleaner (4) of the intake system and on the other hand with the suction chamber (57) communicating with the oil tank (13) via the orifice (58). A handheld four-stroke engine characterized by the following.