WO2010001658A1

WO2010001658A1 - Chain saw

Info

Publication number: WO2010001658A1
Application number: PCT/JP2009/058425
Authority: WO
Inventors: Kouji Koiso; Koichi Shimokawa; Takayoshi Shimazaki
Original assignee: Husqvarna Zenoah Co., Ltd.
Priority date: 2008-07-01
Filing date: 2009-04-22
Publication date: 2010-01-07
Also published as: JP2010012621A

Abstract

A chain saw (1) includes a cooling fan (7) driven by an engine, a carburetor chamber (6) producing a mixture of air and fuel provided to the engine and a side cover (9) covering the cooling fan (7). The side cover (9) is provided with a second intake port (92) for sucking the outer air to feed to the carburetor chamber (6). Inside the side cover (9), an air passage (94) having a substantially linear portion communicating a space receiving the cooling fan (7) with the second intake port (92) and a branch passage (95) branched from the substantially linear portion are provided, the branch passage (95) communicating with a carburetor (4).

Description

DESCRIPTION

Title of Invention

Chain Saw

Technical Field

[0001]

The present invention relates to a chain saw.

Background Art

[0002]

In a chain saw driven by a small-sized engine, an intake system is typically used so that dust such as swarf and cut powder generated during operation is not sucked in a carburetor chamber receiving a carburetor. It is proposed as an example that an intake system includes an intake communicating passage that communicates a proximity of a cooling fan driven by an engine with a carburetor chamber receiving a carburetor, in which clean air separated from dust by a centrifugal separation function of a cooling fan is fed to a carburetor chamber through the intake communicating passage, (see, for example Document 1: JP-A-06- 173797) According to such an intake system, the amount of dust collected in an air filter is reduced, thereby reducing the frequency of maintenance of the chain saw.

Summary of Invention

[0003] An object of the invention is to provide a chain saw that is adapted to blow clean air to a carburetor, while simplifying the maintenance and reducing the size of the chain saw.

[0004] A chain saw according to an aspect of the invention includes: a cooling fan driven by an engine; a carburetor chamber that produces a mixture of air and fuel provided to the engine; and a side cover that covers the cooling fan, in which the side cover is provided with a first intake port that sucks an outer air by the cooling fan and a second intake port that sucks the outer air toward the carburetor chamber, and the side cover is provided therein with an air passage that has a substantially linear portion and communicates a space receiving the cooling fan with the second intake port and a branch passage branched from the substantially linear portion, the branch passage being communicated with the carburetor. [0005]

According to the above aspect of the invention, since an air passage having a substantially linear portion communicating a space receiving the cooling fan with the second intake port and a branch passage branched from the substantially linear portion of the air passage are provided, dust in the air flowing through the air passage is fed through the substantially linear portion to the cooling fan by inertia force and is not fed into the branch passage. Accordingly, dust-free clean air can be fed to the carburetor chamber.

[0006]

In the chain saw according to the above aspect of the invention, the second intake port is preferably disposed in the proximity of the carburetor chamber. [0007]

According to such an arrangement of the invention, since the second intake port is disposed in the proximity of the carburetor, the branch passage can be shortened so that the negative pressure of the engine is effectively acted in the branch passage, so that dust- free clean air can be efficiently fed to the carburetor. [0008]

In the chain saw according to the above aspect of the invention, the branch passage is branched in a direction opposite to a direction of air flowing through the air passage.

[0009] According to such an arrangement of the invention, the air through the air passage and the air through the branch passage flow in a reverse direction to each other, so that the dust in the air passage is easily fed toward the cooling fan, thereby making it less likely for the dust to enter the branch passage.

Brief Description of Drawings

[0010]

Fig. 1 is an exploded perspective view of a chain saw according to an exemplary embodiment of the invention. Fig. 2 is a cross section showing a main part of the chain saw according to the above exemplary embodiment.

Fig. 3 is a cross section schematically showing a proximity of a second intake port and a carburetor chamber according to the above exemplary embodiment.

Description of Embodiments

[0011]

Exemplary embodiment(s) of the invention will be described below with reference to the attached drawings.

Fig. 1 is an entirely schematic exploded perspective view showing a chain saw 1 according to an exemplary embodiment. Fig. 2 is a cross section showing a main part of the chain saw 1.

[0012]

As shown in Fig. 1, the chain saw 1 includes a chain portion (not shown) and a chain saw body 2 provided with an engine for driving the chain portion. A top handle 3 held by an operator is provided on an upper section of the chain saw body 2. A grip 21

(partially shown in Fig. 1) and a hand guard 22 are provided anteriorly to the top handle 3 in the chain saw body 2.

[0013] The chain portion includes a guide bar attached on a side of the chain saw body 2 and extended forward. A sprocket is provided at an end of a crankshaft of an engine through a centrifugal clutch. A saw chain is wound around the sprocket and the guide bar, the saw chain being rotated by the engine. [0014]

The chain saw body 2 includes the engine, a carburetor 4 providing mixture of air and fuel into the engine, an exhaust muffler for emitting exhaust gas out of the engine, and a body cover 23 covering these components.

[0015] The carburetor 4 is attached to the engine through an insulator and an air filter 5 is attached to the carburetor 4. The carburetor 4 and the air filter 5 are received in a carburetor chamber 6 provided posteriorly to the top handle 3. The carburetor chamber 6 is provided as a part of the body cover 23 and is covered with a carburetor cover 24 from the above. [0016]

A cooling fan 7 with a plurality of fins 71 on a circumference thereof is provided at the end of the crankshaft of the engine opposite to the end where the sprocket is provided. An outer circumferential side of the cooling fan 7 is covered with a cooling fan cover 8 having an intake port 81. [0017]

Further, a side cover 9 is provided outside the cooling fan cover 8. The side cover 9 substantially entirely covers the chain saw body 2 on the side of the cooling fan 7. Moreover, the side cover 9 is provided with a plurality of first slit intake ports 91 for sucking the outer air with the cooling fan 7. Second slit intake ports 92 are provided at a position near the carburetor chamber 6 and opposite to the chain portion on the side cover 9. The second intake port 92 is much smaller than the first intake ports in total opening area.

[0018] The cooling fan cover 8 is provided with a bulging portion 82 that is positioned posteriorly to the intake port 81 and bulges outward, a recess 83 that is positioned posteriorly to the bulging portion 82 and is concaved inward and a hollow portion 84 positioned posteriorly to the recess 83. A circular opening 61 communicating with the hollow portion 84 is provided on a bottom surface of the carburetor chamber 6. Further, a cap 10 covering the recess 83 is disposed outside the cooling fan cover 8. The cap 10 includes a lateral portion 101 covering the recess 83, an upper portion 102 provided along an upper edge of the lateral portion 101 and a lower portion 103 provided along a lower edge of the lateral portion 101 to provide a square C-shaped cross section. [0019]

Fig. 3 is a cross section schematically showing a proximity of a second intake port 92 and a carburetor chamber 6.

When the cooling fan cover 8, the side cover 9 and the cap 10 are attached, the lateral portion 101 of the cap 10 and the bulging portion 82 of the cooling fan cover 8 are provided substantially on the same plane. A slit 93 is provided between the cap 10 and the bulging portion 82.

[0020]

Inside the side cover 9, an air passage 94 is provided by a gap between the lateral portion 101 of the cap 10 and the side cover 9 and a gap between the bulging portion 82 and the side cover 9. The second intake port 92 and the cooling fan 7 are communicated through the air passage 94. The air passage 94 is provided substantially in a straight line at least at a position facing the slit 93. A branch passage 95 is provided by a gap between the lateral portion 101 of the cap 10 and the recess 83 of the cooling fan cover 8.

[0021] One end of the branch passage 95 is communicated with the air passage 94 through the slit 93 and the other end of the branch passage 95 is communicated with the carburetor chamber 6 through the circular opening 61. The branch passage 95 is branched in a direction opposite to a direction of air flowing through the air passage 94. The cross sectional area and the length of each of the second intake port 92, the air passage 94 and the branch passage 95 are set considering the engine exhaust. The ratio of the areas of the cross sections is set so that air sucked from the second intake port 92 flows towards the cooling fan 7 at least in a range of the engine speed.

[0022] In the above exemplary embodiment, the outer air with dust sucked from the first intake ports 91 by the cooling fan 7 is sucked in an axial direction relative to the cooling fan 7 through the intake port 81 of the cooling fan cover 8. Then, the sucked outer air changes a flowing direction radially outward to be fed from the outer circumference of the cooling fan to the outer circumference of the engine, thereby cooling down a cylinder and the like as a cooling air. At this time, dust contained in the cooling air is consequently emitted out of the chain saw body 2 together with the cooling air. [0023]

The outer air is also sucked through the second intake port 92 being sucked by the cooling fan 7. The outer air containing dust sucked from the second intake 92 is drawn toward the cooling fan 7 through the air passage 94 (see the solid arrow in Fig. 3) and is mixed with the outer air sucked from the first intake ports 91, thereby cooling the engine.

The outer air is also sucked into the branch passage 95 through the slit 93 from the air passage 94 by negative pressure of the engine. At this time, dust contained in the outer air is fed toward the cooling fan 7 by the inertial force through the air passage 94 substantially in a straight line, so that the dust does not flow from the slit 93 toward the branch passage

95.

[0024]

Consequently, since almost all dust in the outer air is fed through the air passage 94 toward the cooling fan 7, little dust is contained in the outer air sucked into the branch passage 95. Such clean air is sucked through the branch passage 95 into the carburetor chamber 6 (see the dotted arrow in Fig. 3) and is used as an intake of the engine. Accordingly, dust in the intake sucked into the carburetor chamber 6 is reduced and the amount of the dust collected in the air filter 5 is lessened, thereby reducing the frequency of the maintenance of the air filter. [0025]

Incidentally, although one of the best aspects of the exemplary embodiment of the invention is disclosed above, the invention is not limitative. In other words, while the invention has been particularly explained and illustrated mainly in relation to a specific embodiment, those skilled in the art could make various modifications in terms of shape, quantity or other particulars to the above described embodiment without deviating from the technical idea or any object of the present invention.

Accordingly, any descriptions of shape or quantity or the like disclosed above are given as examples to enable easy understanding of the invention, and do not limit the present invention, so that descriptions using names of components, with any such limitations of shape or quantity or the like removed in part or whole, are included in the present invention.

[0026]

Although the second intake port 92 is provided in the proximity of the carburetor chamber 6 in the above exemplary embodiment, the second intake port 92 may be provided, for example, opposite to the carburetor chamber, which may be provided in the chain portion. However, it is preferable that the second intake port 92 is provided in the proximity of the carburetor chamber 6, because the branch passage 95 can be shortened to make the negative pressure of the engine act effectively in the branch passage 95, and because dust is less likely to be sucked when the second intake port 92 is provided on the side opposite to the chain portion.

[0027]

Although the branch passage 95 is branched in a direction opposite to a direction of air flowing through the air passage 94 in the above exemplary embodiment, the branch passage 95 may be branched in a perpendicular direction. However, when the branch passage 95 is branched in a direction opposite to the air passage 94, dust is less likely to enter the branch passage 95. Therefore, it is preferable that the branch passage 95 is branched in a direction opposite to the air passage 94. Industrial Applicability [0028]

The present invention can be preferably applied for a chain saw.

Claims

[Claim 1] A chain saw, comprising: a cooling fan driven by an engine; a carburetor chamber receiving a carburetor that produces a mixture of air and fuel provided to the engine; and a side cover that covers the cooling fan, wherein the side cover is provided with a first intake port that sucks an outer air by the cooling fan and a second intake port that sucks the outer air toward the carburetor chamber, and the side cover is provided therein with an air passage that has a substantially linear portion and communicates a space receiving the cooling fan with the second intake port and a branch passage branched from the substantially linear portion, the branch passage being communicated with the carburetor.

[Claim 2] The chain saw according to claim 1 , wherein the second intake port is disposed in a proximity of the carburetor chamber.

[Claim 3] The chain saw according to claim 1 or 2, wherein the branch passage is branched in a direction opposite to a direction of air flowing through the air passage.