JP4641510B2 - Portable work machine - Google Patents

Description

  The present invention relates to a portable work machine, and more particularly to a portable work machine provided with a separating means and an ejector.

  2. Description of the Related Art Conventionally, portable work machines such as a cut-off saw for cutting a concrete block or the like and a chain saw used for pruning a tree are known. In such a portable work machine, because of the large amount of dust generated during cutting, the engine air cleaner for collecting the dust is quickly clogged, and the air cleaner needs to be frequently cleaned and replaced. There was a problem that it took time and effort for maintenance.

Here, in a large engine used in a construction machine, as a technique for removing dust from the air sent to the air cleaner, a separator that separates the dust from the sucked air and sends it to the air cleaner, and a discharge pipe from the separator are used. There is one that communicates with an exhaust gas passage (for example, Patent Document 1). In such an engine, an ejector is configured at a communication portion between the exhaust pipe and the exhaust gas flow path, and the dust separated by the separator is separated from the separator by the exhaust flow in the exhaust pipe generated by the ejector effect. Since the air is sucked into the exhaust gas passage and discharged to the outside together with the exhaust gas, the maintenance on the air cleaner can be greatly reduced.
Japanese Patent Laid-Open No. 9-236013

  However, when the technique of Patent Document 1 is applied to a portable work machine, the portable work machine is small, so that a discharge pipe for connecting the separator and the exhaust gas passage is formed short. For this reason, when the ejector portion of the discharge pipe is heated with the exhaust gas, the entire discharge pipe is easily heated. In such a state, the exhaust flow flowing in the exhaust pipe is thermally expanded, so that there is a problem that the exhaust flow drawing efficiency by the ejector is deteriorated and the dust discharge efficiency is lowered.

  The objective of this invention is providing the portable working machine which improves the discharge efficiency of dust.

  The portable work machine according to claim 1 of the present invention is the portable work machine, wherein the cooling fan is rotationally driven by the engine, the separating means for separating dust from the air supplied to the engine, and the exhaust gas from the engine. And an exhaust pipe that communicates the ejector and the separation means and passes the exhaust stream, and the exhaust pipe is provided with engine cooling air from the cooling fan. It is arrange | positioned in the cooling air channel | path which passes.

  A portable work machine according to a second aspect of the present invention is the portable work machine according to the first aspect, wherein a plurality of the separation means are provided, and each of the separation means is provided in a gravity direction. A discharge port is provided, and a dust collection chamber for sending dust discharged from the discharge port to the discharge pipe is provided almost directly below the discharge port of the separation means, and the plurality of separation means and the dust collection chamber are provided. Is formed integrally.

According to the first aspect of the present invention, since the middle of the exhaust pipe is arranged in the cooling air passage through which the engine cooling air from the cooling fan passes, the engine cooling air from the cooling fan is excellent in the exhaust pipe. Can be applied.
Therefore, when applying a mechanism for discharging dust with an ejector to a portable work machine, even if the discharge pipe is formed short and is easily heated by the heat of the exhaust gas, the cooling of the engine from the cooling fan is performed. Since the discharge pipe can be sufficiently cooled by the wind, the discharge flow in the discharge pipe can be prevented from thermally expanding, and the dust discharge efficiency can be improved.

  According to the invention of claim 2, a plurality of separating means are provided with a discharge port opened in the direction of gravity, and a hopper-shaped dust collecting chamber is provided substantially directly under the discharge port. Therefore, the dust in the separating means can be reliably dropped to the discharge port and discharged into the dust collection chamber, and the dust discharge efficiency can be further improved.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a side view showing a structure around an engine 3 mounted on a cut-off saw 1 (portable work machine) of the present embodiment, and FIG. 2 is a cross-sectional view showing around the engine 3.

As shown in FIG. 1 and FIG. 2, the cut-off saw 1 is a hand-held portable work machine that cuts a concrete lump, roadbed material, etc. , A guide member (not shown) provided forward from the cut-off saw body 11, a cutter head attached to the tip of the guide member, and a cutter blade 12 attached to the cutter head, It has.
A clutch housing 14 for a centrifugal clutch is provided on one end side (left side in FIG. 2) of the crankshaft 13 of the engine 3, and a belt is wound around the clutch housing 14 and a pulley provided on the cutter head. Thereby, the blade mounting part connected to the pulley on the cutter head side is driven by the engine 3 via the belt, and the cutter blade 12 rotates.
A cooling fan 15 for sending cooling air to the engine 3 is provided on the other end side (right side in FIG. 2) of the crankshaft 13, and a recoil starter 16 is provided outside the cooling fan 15 via a ratchet mechanism. It has been.

  Here, the engine 3 of the present embodiment is a stratified scavenging type two-cycle engine, and is connected to a scavenging passage 33 from a leading air intake port 31 formed on the inner peripheral surface of the cylinder 30 via a groove on the outer periphery of a piston (not shown). The leading air can be sucked into the upper part. For this reason, during the scavenging stroke, the leading air scavenges the combustion gas first, so that the fuel efficiency is improved and the exhaust gas is cleaned compared to a normal two-cycle engine in which the air-fuel mixture scavenges the combustion gas. be able to.

FIG. 3 is a side view showing a main part around the engine 3.
In FIG. 3, a cleaner box 4 using the cover 2 is provided on the rear side (right side in FIG. 3) of the engine 3. In this cover 2, the portion of the cleaner box 4 is detachably provided with respect to the attachment portion 41 to which the air cleaner 40 is attached.
On the upper front side of the cleaner box 4, there is provided an axial flow type centrifugal separator 5 (separating means) for separating dust from the sucked air and sending it to the cleaner box 4.

FIG. 4 is a cross-sectional view taken along line AA of FIG. 3 showing the centrifugal separator 5 and the dust collection chamber 6.
As shown in FIG. 3 and FIG. 4, the centrifuge 5 includes a substantially cylindrical tube portion 50 provided in the attachment portion 41 of the cleaner box 4, and an inside of the cylinder portion 50 and the cleaner provided in the attachment portion 41. A diverging delivery pipe 51 communicating with the inside of the box 4 is configured. In the vicinity of the suction port 52 of the cylindrical part 50, a guide wing 53 for turning the sucked air is provided. Further, as shown in FIG. 4, a discharge port 54 opened in the direction of gravity is provided below the delivery pipe 51 in the vicinity of the outlet of the cylindrical portion 50. In the present embodiment, such three centrifugal separators 5A, 5B, 5C are arranged substantially horizontally.

  A dust collection chamber 6 communicating with each discharge port 54 is provided immediately below the discharge port 54 of the centrifugal separator 5. The dust collection chamber 6 is formed in a hopper shape by the first side surface portion 60, the second side surface portion 61, the front surface portion 62, and a part of the attachment portion 41. A mounting pipe 64 having a suction port 63 is extended below the dust collection chamber 6. In the present embodiment, the centrifugal separators 5A, 5B, and 5C, the first and second side surface portions 60 and 61 and the front surface portion 62 that constitute the dust collection chamber 6, and the attachment tube 64 are integrally formed. As shown in FIG. 3, one end side of the discharge pipe 7 is attached to the attachment pipe 64 via a connection pipe 65 made of synthetic resin.

  A pipe 42 is attached between the cleaner box 4 and the engine 3 to send the air that has passed through the air cleaner 40 to the engine 3 side as the leading air, and below this pipe 42 is the air that has passed through the air cleaner 40. A carburetor 43 that supplies fuel to the air-fuel mixture is disposed. A pipe 44 is attached between the carburetor 43 and the engine 3 to send the air-fuel mixture that has passed through the carburetor 43 to the engine 3 side.

  On the other hand, a muffler 9 having a diffuser 8 at the exhaust port portion is provided on the front side of the engine 3. The diffuser 8 has a divergent shape having a throttle portion 80 at a portion from the base end side, and an inlet 81 of the diffuser 8 is provided inside the muffler 9, and outside the muffler 9, A discharge port 82 opened toward the front (left in FIG. 3) is provided. The tip end side of the discharge pipe 7 described above is drawn into the muffler 9. Inside the muffler 9, a nozzle 70 having a small diameter is provided on the distal end side of the discharge pipe 7, and the distal end of the nozzle 70 is located in the throttle portion 80 of the diffuser 8 in this embodiment. The ejector 100 is configured by the nozzle 70 and the diffuser 8.

  As shown in FIGS. 2 and 3, the middle of the discharge pipe 7 is formed in a substantially linear shape and is disposed above the cooling fan 15. As shown in FIG. 2, a cooling air passage 71 covered with the cover 2 is formed above the cooling fan 15, and the middle of the discharge pipe 7 passes through the cooling air passage 71. Has been placed. By doing so, it is possible to cool the discharge pipe 7 with the cooling air for the engine 3 from the cooling fan 15.

Below, the effect | action of this embodiment is demonstrated.
The air containing the dust sucked into the centrifugal separator 5 is swirled by the guide blades 53 provided near the suction port 52. By making the swirl flow, centrifugal force acts on the dust having a large mass, and the dust is separated from the sucked air. The separated dust advances toward the discharge port 54 while rotating around the inner periphery of the cylinder portion 50 at a high speed, and is discharged from the discharge port 54 to the dust collecting chamber 6. On the other hand, the air from which the dust is separated as a swirling flow advances in the cylinder portion 50 toward the delivery pipe 51 and is sucked into the cleaner box 4 from the delivery pipe 51. The air sucked into the cleaner box 4 is finely filtered by the air cleaner 40 and then sent to the engine 3 side as the leading air from the pipe 42 side, and the air-fuel mixture supplied with fuel from the carburetor 43 side. Is sent to the engine 3 side.

  On the other hand, the exhaust gas scavenged on the engine 3 side is sent from the exhaust passage into the muffler 9 and discharged to the outside front through the diffuser 8. At this time, the exhaust gas acts as a driving gas when passing through the throttle portion 80 in the diffuser 8. Then, due to the ejector effect of the driving gas, a discharge flow is generated in the discharge pipe 7, and the dust discharged from the centrifugal separator 5 to the dust collecting chamber 6 rides on the discharge flow in the discharge pipe 7 to the nozzle 70. It is carried and is drawn into the exhaust gas passing through the throttle 80 from the nozzle 70 and discharged from the discharge port 82 together with the exhaust gas.

At this time, the cooling air passage 71 through which the cooling air for the engine 3 passes is formed above the cooling fan 15, and the middle of the discharge pipe 7 is disposed in the cooling air passage 71. The cooling air for the engine 3 from the fan 15 can be satisfactorily applied.
That is, in the present embodiment in which a mechanism for discharging dust by the ejector 100 is applied, the discharge pipe 7 is formed short, so that it is easily heated by the heat of the exhaust gas from the portion disposed inside the muffler 9. However, the cooling air for the engine 3 from the cooling fan 15 can be sufficiently cooled. Therefore, it is possible to suppress thermal expansion of the discharge flow in the discharge pipe 7 and improve the dust discharge efficiency. In addition, since the discharge pipe 7 can be sufficiently cooled, the thermal influence on the connecting pipe 65 made of synthetic resin can be suppressed.

In addition, the centrifugal separators 5 arranged substantially horizontally are provided with a discharge port 54 opened in the direction of gravity, and a hopper-shaped dust collection chamber 6 is provided substantially directly below the discharge port 54. In addition, the dust rotating around the cylinder portion 50 of the centrifugal separator 5 can be reliably dropped into the discharge port 54 and discharged into the dust collection chamber 6, and the dust discharge efficiency can be further improved.
Moreover, since the centrifugal separators 5A, 5B, and 5C, the first and second side surfaces 60 and 61 and the front surface 62 that constitute the dust collecting chamber 6, and the attachment pipe 64 are integrally formed, the number of parts is increased. The manufacturing cost can be reduced.

In addition, this invention is not limited to the said embodiment, Including other structures etc. which can achieve the objective of this invention, the deformation | transformation etc. which are shown below are also contained in this invention.
For example, in the present embodiment, the separation means is the axial flow type centrifugal separation unit 5, but may be an inversion type centrifugal separation unit 5 or a forced vortex type centrifugal separation unit 5. These separation methods are centrifugal separation methods, but in addition to the separation unit 5 employing the centrifugal separation method, a separation unit 5 employing a gravity separation method or an inertial separation method may be used. Although a plurality of centrifuge units 5 are provided and integrally formed, a plurality of centrifuge units 5 may not be provided. The dust collection chamber 6 may not be formed integrally with the centrifugal separator 5.

  The present invention can be effectively used for portable work machines such as a cut-off saw and a chain saw.

The side view which shows the structure around an engine. Sectional drawing which shows an engine periphery. The side view which shows the principal part around an engine. AA line sectional view of Drawing 3 showing a centrifuge and a dust collection room.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Cut-off saw (portable working machine), 3 ... Engine, 5 ... Centrifugal separation part (separation means), 6 ... Dust collection chamber, 7 ... Discharge piping, 15 ... Cooling fan, 54 ... Discharge port, 71 ... Cooling air passage, 100 ... ejector.

Claims (2)

In portable work machines,
A cooling fan driven to rotate by the engine;
Separation means for separating dust from the air supplied to the engine;
An ejector that causes exhaust flow using exhaust gas from the engine as drive gas,
A discharge pipe for communicating the ejector and the separation means to pass the discharge flow;
A portable work machine, wherein the exhaust pipe is disposed in a cooling air passage through which engine cooling air from the cooling fan passes. The portable work machine according to claim 1, wherein
A plurality of the separating means are provided,
Each of the separation means is provided with a discharge port provided in the direction of gravity,
A dust collection chamber for sending dust discharged from the discharge port to the discharge pipe is provided almost immediately below the discharge port of the separating means.
The plurality of separating means and the dust collecting chamber are integrally formed.

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