JPH112112A - Crank case of portable four-cycle engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a lower edge of a crank web from soaked in an oil face, by projecting a lower part of a bearing boss to a cooling fan side, and comprising a side wall provided with a recesss part, at a cooling fan side, to reduce the change of the oil face between an inclined condition and an upright condition. SOLUTION: In a crank case 9 at a cooling fan side, a lower part of a bearing boss 9a is projected to a cooling fan 7 side, and a recessed part for reducing the elevation of an oil face F1 is formed. When a portable four cycle engine 1 is inclined to the cooling fan 7 side, an lubricating oil in an oil reservoir 13 is flown into the recessed part of a side wall 9c at the cooling fan side, so that the elevation of the oil face F1 can be reduced for that amount. That is, the recessed part of the crank case 9 at the cooling fan side and a inclined wall 10c of a crank case 10 at a non- cooling fan side are formed in such manner that the increase and decrease of a variable amount of lubricating oil at the cooling fan side and that at the non-cooling fan side are almost agreed with each other to a central axis 3a of a piston. That is, the oil face F1 passes through an almost P point regardless of an inclining direction, so that an interval L1 between the oil face and the lowermost edge of the crank web 4b becomes almost uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a crankcase of a portable four-stroke engine, and more particularly to a crankcase of a portable four-stroke engine mounted on a portable work machine such as a mower.

[0002]

2. Description of the Related Art Conventionally, a portable four-stroke engine mounted on a working machine such as a mowing machine lubricates the engine by splashing up lubricating oil of a crankcase. As an example of such a pop-up type portable four-stroke engine crankcase, Japanese Utility Model Publication No. 8-7050 shown in FIG. 12 will be described. The crankcase 50 of the portable four-stroke engine includes an oil reservoir 50a that rotatably supports a crankshaft 51 and a cooling fan 52 fixed on the crankshaft 51, and that stores a lubricating oil of a jump-up type. ing. A connecting rod 55 is pivotally supported by the piston 54 and the crankshaft 51 that reciprocate in the cylinder 53, and the lubricating oil in the oil reservoir 50a is jumped up by a jumping member 56 fixed to the connecting rod 55, The sliding portion between the cylinder 53 and the piston 54 is lubricated. When the portable four-stroke engine is inclined at a predetermined angle α toward the cooling fan 52 when driving a mower or the like,
The oil level changes from F1 to F2 so that GAB = GCD. Therefore, the uppermost portion of the oil level F2 is D, and the crankshaft 51 is shifted from the oil level F1 by ΔH = (L / 2) tan α.
In the upright position, the lower end of the crank web 51a does not immerse in the lubricating oil surface F1, but the lower end of the crank web 51a is easily immersed in the lubricating oil surface F2 when inclined.

[0003]

When the conventional portable four-stroke engine is used for an operation such as a mower or the like in which the posture of the engine is drastically changed, the lower end of the crank web 51a is frequently immersed in the oil level F2. For this reason, there is a problem that a power loss due to the stirring of the lubricating oil by the crank web 51a and a so-called oil-up phenomenon in which the lubricating oil stirred by the crank web is burned and consumed in the cylinder.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and it is intended to reduce the change of the oil level at the time of inclining with respect to the upright state, and to reduce the oil level between the lower end of the crank web and the oil level at the time of inclining in opposite directions. It is an object of the present invention to provide a crankcase of a portable four-stroke engine in which a change in the interval of the engine is reduced.

[0005]

In order to achieve the above object, a first invention of a crankcase of a portable four-stroke engine according to the present invention is provided in which a piston reciprocating in a cylinder rotates through a connecting rod. The driven crankshaft and the cooling fan fixed on the crankshaft are rotatably supported, and the bearing boss installed between the piston center shaft and the cooling fan, and the lubricating oil of the flip-up type In a crankcase of a portable four-stroke engine having an oil sump, a lower portion of a bearing boss protrudes toward a cooling fan to reduce a rise in oil level when the portable four-stroke engine is inclined toward the cooling fan. The cooling fan side wall provided with the cooling fan is provided.

According to the structure of the first aspect of the invention, when the portable four-stroke engine is inclined toward the cooling fan, the lubricating oil in the oil reservoir flows into the recess on the side wall of the cooling fan, and the oil level rises accordingly. Reduced. For this reason, even if the cooling fan side wall other than the concave portion is protruded to the opposite side to the cooling fan, the change in the oil level when inclined with respect to the upright state is reduced,
When the portable four-cycle engine is tilted, the lower end of the crank web is less likely to be immersed in the oil surface. Therefore, the power loss due to the stirring of the lubricating oil by the crank web and the so-called oil-up phenomenon in which the lubricating oil stirred by the crank web is burned and consumed in the cylinder are reduced.

A second invention of a crankcase for a portable four-stroke engine according to the present invention is the invention according to the first invention, wherein the cooling fan is formed on the cooling fan side walls on the left and right sides of the bearing boss above the recess. It is characterized by having a cooling air intake for taking in air.

According to the structure of the second aspect of the invention, the cooling air inlet is provided above the concave portion of the cooling fan side wall, at a portion where the cooling fan side walls on the left and right sides of the bearing boss project to the opposite side to the cooling fan. You. For this reason, a cooling air intake is formed between the crankcase and the cooling fan, so that the configuration of the crankcase can be made compact and the intake of dust generated from a working machine installed in the crankshaft direction such as a mower is used. Is prevented.

A portable four-stroke engine crankcase according to a third aspect of the present invention includes a crankshaft driven by a piston reciprocating in a cylinder through a connecting rod and a cooling fan fixed on the crankshaft. In a crankcase of a portable four-stroke engine having a bearing boss rotatably supported and provided between a piston center shaft and a cooling fan, and an oil sump for storing a lubricating oil of a flip-up type, And an outer peripheral wall of the crankcase formed substantially concentrically with the axis center of the crankcase.

According to the third aspect of the invention, since the outer peripheral wall of the crankcase is formed substantially concentrically with the center of the axis of the crankshaft, the portable four-stroke engine can be moved from the upright state to the center of the axis of the crankshaft. When inclined, the height of the lubricating oil surface is always substantially constant regardless of the inclination direction and the inclination angle. For this reason, even if the working posture of the portable four-stroke engine changes sharply, such as when mowing, the lower end of the crank web does not immerse in the oil surface, and the amount of splashing oil can be kept constant. Accordingly, power loss due to the crank web stirring the lubricating oil, and the lubricating oil stirred by the crank web are burned and consumed in the cylinder,
The so-called oil-up phenomenon is reduced, and stable lubrication is obtained.

[0011] In the crankcase for a portable four-cycle engine according to the fourth invention, in the third invention, the lower portion of the bearing boss is protruded toward the cooling fan, and when the portable four-cycle engine is inclined toward the cooling fan, the oil is reduced. A concave portion for reducing the elevation of the surface, a cooling fan side wall in which a cooling air intake is formed by projecting to the opposite side of the cooling fan to the left and right of the bearing boss above the concave portion, and a cooling fan with respect to the center axis of the piston. An inclined outer wall that extends upward and outward from the outer peripheral wall on the side opposite to the side wall, and cools the piston center axis when inclined to the cooling fan side and the anti-cooling fan side of the portable four-cycle engine. It is characterized in that the amount of lubricating oil that increases and decreases on the fan side and the anti-cooling fan side is formed substantially the same.

According to the structure of the fourth aspect of the invention, the cooling air inlet is provided above the concave portion of the cooling fan side wall, at a portion where the cooling fan side walls on the left and right sides of the bearing boss project to the opposite side to the cooling fan. You. For this reason, a cooling air intake is formed between the crankcase and the cooling fan, so that the configuration of the crankcase can be made compact and the intake of dust generated from a working machine installed in the crankshaft direction such as a mower is used. Is prevented. Further, when the portable four-cycle engine is inclined toward the cooling fan side and the anti-cooling fan side, the amount of lubricating oil on both sides which increases and decreases with respect to the piston center axis is substantially the same. If the inclination angle is the same, the distance between the lubricating oil surface and the lowermost end of the crank web becomes substantially the same regardless of the inclination direction. Therefore, even if the working posture of a portable four-stroke engine such as a mower changes drastically, there is no contact between the lubricating oil surface and the lowermost end of the crank web, and there is no agitation of the lubricating oil by the web. And there is no rise in oil temperature.

According to a fifth aspect of the present invention, there is provided a crankcase for a portable four-stroke engine according to the fourth aspect, wherein an upwardly concave fuel tank is attached along a lower portion of the outer peripheral wall and the inclined outer wall, and an upper portion of the fuel tank is provided. A communication passage connecting the comrades is arranged below the inclined outer wall.

According to the structure of the fifth aspect of the invention, if the communication passage of the fuel tank is arranged along the lower part of the inclined outer wall, the fuel tank that fits in the lower part of the inclined outer wall is formed compact.
Further, even if fuel is supplied from one upper portion of the fuel tank having a concave shape upward and fuel is supplied to the lowest upper wall of the fuel tank, fuel is supplied to the other upper portion via the communication path, Both upper portions of the concave fuel tank can be filled with fuel. As a result, fuel can be supplied without tilting the portable four-stroke engine, so that refueling work can be streamlined.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 and 2, a connecting rod 5 pivotally supported by a piston 3 (see FIG. 2) reciprocating in a cylinder 2 of a portable four-cycle engine 1 and a crankpin 4a of a crankshaft 4 has an oil scraper. The member 6 is fixed. A cooling fan 7 is fixed on the crankshaft 4, and the power of the crankshaft 4 is output from an output shaft 8 to a working machine such as a mower.
The crankcase includes a cooling fan-side crankcase 9 and an anti-cooling fan-side crankcase 10 with a center axis 3a of the piston 3 as a boundary. Between the cooling fan 3a and the cooling fan 7, it is rotatably supported by a bearing 11 installed on a bearing boss 9a of the cooling fan side crankcase 9. The other end of the crankshaft 4 is rotatably supported by a bearing 12 installed on a bearing boss 10a of the anti-cooling fan side crankcase 10. In addition, both-side crankcase 9,
An oil reservoir 13 for storing a lubricating oil of a flip-up type is provided at a lower portion of 10.

The outer peripheral walls 9b, 10b of the cooling fan side crankcase 9 and the non-cooling fan side crankcase 10 are
It is formed substantially concentrically with the shaft center G of the crankshaft 4.
An inclined outer wall 10c extending upward and outward is continuously provided on an outer peripheral wall 10b of the anti-cooling fan side crankcase 10. The cooling fan-side crankcase 9 and the non-cooling fan-side crankcase 10 are arranged such that when the portable four-cycle engine 1 is inclined to the cooling fan side and the non-cooling fan side, the cooling fan side with respect to the piston center axis 3a. And the amount of each lubricating oil that increases and decreases on the side opposite to the cooling fan. Anti-cooling fan side crankcase 10
A concave fuel tank 14 is attached upward along the outer peripheral wall 10b and the lower part of the inclined wall 10c. Fuel tank 14
As shown in FIG. 3, upper portions 14a and 14b are connected to each other through a communication passage 14c, and the communication passage 14c is disposed close to a lower portion of the inclined wall 10c.

The details of the cooling fan side crankcase 9 are shown in FIGS. The cooling fan side crankcase 9 has a recessed portion for lowering the oil level F1 when the portable four-cycle engine 1 is inclined toward the cooling fan 7 by projecting a lower portion of the bearing boss 9a toward the cooling fan 7 side. 13a (the range shown by oblique lines rising to the right in FIG. 5) is installed. Above the recess 13a, on the cooling fan side wall 9c on the left and right of the bearing boss 9a,
Portions 13b and 13 projecting to the side opposite to cooling fan 7
b (in the range indicated by oblique lines falling to the right in FIG. 5), the cooling fan 7
The cooling air inlets 7a, 7a for taking in the cooling air are formed at right angles to the direction of the crankshaft 4.

The operation of the above configuration will be described. When the portable four-cycle engine 1 is tilted toward the cooling fan 7, the lubricating oil in the oil reservoir 13 flows into the recess 13a of the cooling fan side wall 9c, so that the oil level F1 is reduced by that much. Thus, the recess 13a of the cooling fan side crankcase 9 and the anti-cooling fan side crankcase 1
The 0 inclined wall 10c means that when the portable four-stroke engine 1 is inclined between the cooling fan side and the anti-cooling fan side, each of the number increases and decreases between the cooling fan side and the anti-cooling fan side with respect to the piston center axis 3a. The lubricating oil amounts are formed so as to be substantially the same. That is, since the oil level F1 passes through the point P substantially regardless of the inclination direction, the distance L1 between the oil level F2 and the lowermost end of the crank web 4b is substantially the same.

For this reason, even if the cooling fan side wall 9c other than the concave portion 13a has a shape protruding on the side opposite to the cooling fan 7, the portable four-cycle engine 1 shown in FIG. As shown, when the portable four-stroke engine 1 is inclined at a predetermined angle α (30 °) toward the cooling fan 7, the distance L2 between the lubricating oil surface F2 and the lowermost end of the crank web 4a decreases from L1 to L2. I do. Further, from the upright state of the portable four-cycle engine 1 shown in FIG. 1, as shown in FIG.
When inclined by (30 °), the distance between the lubricating oil surface F2 and the lowermost end of the crank web 3a decreases from L1 to L2. Therefore, even if the working posture of a portable four-stroke engine such as a mower changes drastically, there is no contact between the lubricating oil surface and the lowermost end of the crank web, and there is no agitation of the lubricating oil by the web. And there is no rise in oil temperature.

Above the recess 13a, the cooling boss inlet 9a projecting to the opposite side to the cooling fan 7 and the cooling fan side walls 9c on the left and right sides are formed at right angles to the crankshaft 4 direction.
By forming 7a, the configuration of the crankcase can be made compact, and inhalation of dust generated from a working machine installed in the crankshaft direction such as a mower can be prevented. Along the lower part of the inclined outer wall 10c of the anti-cooling fan side crankcase 10, the fuel tank 1
By arranging the four communication passages 14c, the fuel tank 14 can be compactly stored below the inclined outer wall 10c. Further, even if the fuel is supplied from one upper portion 14a of the fuel tank 14 and the fuel is supplied to the lowest upper wall 14d of the fuel tank 14, the other upper portion 14a is communicated through the communication passage 14c.
b, the fuel can be supplied to both upper portions 14a, 14b of the fuel tank 14. As a result, the fuel tank 14 becomes compact, and fuel can be supplied without tilting the portable four-stroke engine 1, so that the refueling operation can be made more efficient.

Outer peripheral walls 9b, 1 of the crankcases 9, 10
Since 0b is formed substantially concentrically with the shaft center G of the crankshaft 4, when the portable four-stroke engine 1 is tilted from the upright state around the shaft center G of the crankshaft 4, it depends on the tilt direction and the tilt angle. The height L1 of the oil level F1 is always substantially constant. For this reason, from the upright state of the portable four-cycle engine 1 shown in FIG. 2, the predetermined angle β is turned counterclockwise around the axis G of the crankshaft 3 as shown in FIG.
(30 °) or, as shown in FIG. 11, even if it is inclined clockwise by a predetermined angle β (30 °), the distance L1 between the oil surface F1 and the lowermost end of the crank web 4a does not change. . Therefore, even if the working posture of the portable four-stroke engine 1 changes drastically as in mowing work, the lubricating oil surface does not come into contact with the lowermost end of the crank web, and the lubricating oil is not agitated by the web. No power loss and no increase in oil temperature.

[Brief description of the drawings]

FIG. 1 is a partial side sectional view showing an upright state of a portable four-stroke engine.

2 is a cross-sectional view taken along line AA of FIG. 1 on the left side of the center, and FIG.
It is ABBA sectional drawing of FIG.

FIG. 3 is a sectional view taken along line DDA of FIG. 1;

FIG. 4 is a perspective view of a cooling fan side crankcase.

FIG. 5 is a view taken in the direction of the arrow V in FIG. 4;

FIG. 6 is a sectional view taken along line EE of FIG. 4;

FIG. 7 is a sectional view taken along line FF of FIG. 4;

FIG. 8 is a diagram showing a state in which the vehicle is inclined from the upright state in FIG. 1 toward the cooling fan;

FIG. 9 is a diagram showing a state in which the vehicle is tilted from the upright state in FIG. 1 to the side opposite to the cooling fan.

FIG. 10 is a view inclining counterclockwise from the upright state of FIG. 2;

FIG. 11 is a diagram inclined clockwise from the upright state of FIG. 2;

FIG. 12 is a diagram showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Portable 4-cycle engine 2 Cylinder 3 Piston 3a Center axis of piston 4 Crankshaft 7 Cooling fan 7a Cooling air inlet 8 Output shaft 9 Cooling fan side crankcase 9a, 10a Bearing boss 9b, 10b Outer wall 9c Cooling fan side wall Reference Signs List 10 Anti-cooling fan side crankcase 10c Inclined outer wall 13a Recess 14 Fuel tank 14a One upper portion 14b The other upper portion 14c Communication passage 14c Upper wall G Crankshaft shaft center F1, F2 Oil level

Claims (5)

[Claims] 1. A piston reciprocating in a cylinder (2)
(3) rotatably supports a crankshaft (4) rotatably driven via a connecting rod (5) via a connecting rod (5) and a cooling fan (7) fixed on the crankshaft (4). In a crankcase of a portable four-stroke engine having a bearing boss (9a) installed between a shaft (3a) and a cooling fan (7) and an oil sump (13) for storing lubricating oil of a flip-up type, Extend the lower part of the boss (9a) toward the cooling fan (7),
A portable four-stroke engine having a cooling fan side wall (9c) provided with a concave portion (13a) for reducing an increase in oil level when the portable four-cycle engine is inclined toward the cooling fan (7).
Cycle engine crankcase. 2. The cooling air according to claim 1, wherein the cooling air is formed on the cooling fan side walls (9c) on the left and right sides of the bearing boss (9a) above the recess (13a) and takes in the cooling air of the cooling fan (7). A portable four-stroke engine crankcase having an intake (7a). 3. A piston reciprocating in a cylinder (2).
(3) rotatably supports a crankshaft (4) rotatably driven via a connecting rod (5) via a connecting rod (5) and a cooling fan (7) fixed on the crankshaft (4). In a portable four-stroke engine crankcase having a bearing boss (9a) installed between a shaft (3a) and a cooling fan (7) and an oil reservoir (13) for storing a lubricating oil of a jumping type, A crankcase for a portable four-stroke engine, comprising: an outer peripheral wall (10b) of a crankcase (10) formed substantially concentrically with an axis center (G) of a shaft (4). 4. The engine according to claim 3, wherein a lower portion of the bearing boss (9a) is protruded toward the cooling fan to prevent the oil level from rising when the portable four-cycle engine (1) is inclined toward the cooling fan (7). The recess (13a) to be reduced and the bearing boss (9) above the recess (13a)
a) A cooling fan side wall (9c) formed on the left and right sides opposite to the cooling fan (7) to form a cooling air inlet (7a), and the cooling fan side with respect to the piston center axis (3a). Equipped with an inclined outer wall (10c), which is opposite to the side wall (9c) and extends upward and outward from the outer peripheral wall (10b), and is anti-cooled from the cooling fan (7) side of the portable four-cycle engine (1). A portable type 4 characterized in that the amount of lubricating oil to be increased and decreased on the side of the cooling fan (7) and on the side of the anti-cooling fan with respect to the piston central axis (3a) when tilting to the fan side is substantially the same. Cycle engine crankcase. 5. A fuel tank according to claim 4, wherein a concavely upwardly extending fuel tank (14) is attached along a lower portion of the outer peripheral wall (10b) and the inclined outer wall (10c). 14a, 14
b) A portable four-stroke engine crankcase characterized in that a communication path (14c) connecting the comrades is arranged below the inclined outer wall (9c).