JP6421054B2 - Portable work machine - Google Patents

Description

  The present invention relates to a portable work machine having an engine as a power source.

  2. Description of the Related Art Conventionally, portable work machines that cut a lump of concrete called a cut-off saw or an engine cutter are known. Engine cutters, especially those that generate dust, such as concrete, are clogged and the engine air cleaner becomes clogged, causing engine power-down and reducing workability. There is a problem to do.

  For example, as in Patent Document 1, the first-stage air filter non-woven fabric and the second-stage air filter filter paper filter element are separated, and the upper part of the filter box to which the filter paper filter element has been delivered is covered with a wire mesh. Cover it with a non-woven fabric, and then cover it with a lid that can be opened and closed on the filter box, and fix the non-woven fabric with an air intake, so that it is easy to clean or replace when the air filter device is clogged. There are known ones that facilitate the attachment and removal of the nonwoven fabric of the first-stage air filter and reduce the cleaning time.

Utility Model Registration No. 3030620

  However, the air filter as in Patent Document 1 has a problem that it is troublesome to frequently replace the air filter although the replacement time is shortened.

  Further, it is known that a portable working machine uses a mixed lubrication engine that uses a mixed fuel of gasoline and lubricating oil so that the engine can be operated even when the engine is inclined. Moreover, the air filter used in such a portable work machine has an extremely large amount of dust as compared with an air filter of an automobile, and the usage environment is significantly different from that of an automobile air filter.

  The present invention has been made in view of the above points, and the object of the present invention is to improve the dust collecting ability of the air filter and prevent the dust and water from being mixed into the intake air of the engine. The purpose is to improve the durability of the engine.

  In order to achieve the above object, in the present invention, a filter paper filter and a nonwoven fabric filter are arranged in series in a filter cover of an intake passage of an engine.

  Specifically, the first invention presupposes a portable work machine including an air filter that sends fresh air to an engine that is a power source.

And the portable work machine is
A filter cover for housing the air filter;
In the filter cover, an upstream first filter and a downstream second filter are stacked, the first filter is a columnar filter paper filter, and the second filter is a plate-like filter. nonwoven filter der of is, the a first filter and a second filter, that is housed side by side in series with the cylindrical of the filter cover while keeping a clearance from each other in the air flow direction.

  That is, only the first filter made of a filter paper filter cannot capture fine dust sufficiently, but according to the above configuration, the fine filter that the first filter could not capture can be captured by the second filter made of a nonwoven fabric filter. it can. Further, compared with the case of only the first filter, since the second filter is provided, the ventilation resistance is increased, the region where the flow velocity is locally large is reduced, and the dust transmitted through the filter paper by the high-speed fluid is reduced. More specifically, since the intake port of the carburetor is usually smaller than the filtration surface of the first filter, the flow velocity is high immediately above (in the projection part) of the intake port of the first filter, and slow in a place far from the projection part. However, by adding the second filter, the flow velocity in the first filter is made uniform by the ventilation resistance, so that an effect that dust is easily captured in the first filter is produced.

In addition, even if fuel blows back, it adheres to the nonwoven fabric filter on the downstream side, so the fuel does not reach the filter paper filter, and the filter paper filter's filter paper and adhesive will deteriorate, causing the filter paper filter to break and leak dust Decreases. Even if there is a local concentration of negative pressure in the first filter, the air moves in the gap, making it easy to disperse. By this gap, the second filter equalizes the flow velocity in the first filter. The function to make it more effective. Further, since there is a gap, fuel and lubricating oil attached to the second filter do not infiltrate the first filter. For example, the first filter may be a columnar shape or a quadrangular prism shape, and the second filter may be a disc shape or a square plate shape. Accordingly, the filter cover may be cylindrical or rectangular.

In the second invention, in the first invention,
Air is configured to flow linearly in the order of the first filter, the gap, and the second filter from the inlet on one end side of the filter cover to the outlet on the other end side.

According to said structure, since air flows linearly in order of a 1st filter, a clearance gap, and a 2nd filter, the function in which the 2nd filter equalizes the flow rate in a 1st filter becomes more effective.

In the third invention, in the first or second invention,
The first filter is a columnar filter paper filter,
The first filter and the second filter have the same cross section cut by a plane perpendicular to the air flow direction .

With the above structure, since the cross section of the first filter and the second filter is the same shape, easy second filter effect of equalizing the flow velocity in the first filter is exhibited.

In the fourth invention, in the portable work machine provided with an air filter for sending fresh air to the engine as a power source,
A cylindrical filter cover for housing the air filter;
Inside the filter cover, an upstream first filter and a downstream second filter are stacked vertically.
The first filter is a filter paper filter,
The second filter is a non-woven filter,
The air filter is provided on the upper side of the portable work machine, and includes a filter chamber provided with an inlet on the upstream side of the air filter,
The space in the filter chamber from the inlet to the inlet opening of the filter cover constitutes a variable absorption space that absorbs changes in flow velocity and pressure in the space .
The bottom surface forming the fluctuation absorbing space is inclined downward from the lower end portion of the filter cover toward the opposite side of the inflow port .

According to the above configuration, by providing the fluctuation absorption space including a relatively large space in front of the air filter, when the air that has come out from the downstream flows into the wide fluctuation absorption space, the flow velocity and pressure are reduced. . For this reason, the speed of the dust colliding with the air filter is reduced, and the filter is less mechanically worn. Therefore, damage to the lattice in the filter due to wear is reduced, and the reduction in dust particle capturing ability is reduced. be able to. Coarse dust particles are trapped by the grids in the filter, but if the inflow pressure to the filter is large, the dust particles trapped by the eyes are pushed into the eyes and pass through the grids. However, permeation of such dust particles can be reduced by the above configuration. In addition, fine dust particles are more easily transmitted through the grid in the filter as they flow into the filter due to high-speed air flow, but the flow velocity is reduced by the above configuration, so that the dust particles are more contacted by the grid in the filter. It becomes easy to capture by filtration. Moreover, the space of the filter chamber expands downward due to the inclined shape of the bottom surface forming the variable absorption space. Air flow is also generated below the filter cover that fixes the air filter, so that heavy dust and water droplets (fog) are more effectively dropped by gravity and do not reach the inlet of the air filter above it. can do. Furthermore, dust that has flowed into the space in front of the air filter can be deposited on the entire bottom surface including the region extending downward, and the amount of dust deposited on the inlet of the air filter can be reduced. , Maintenance period is longer.

In the fifth invention, in the portable work machine provided with an air filter for sending fresh air to the engine as a power source,
A cylindrical filter cover for housing the air filter;
Inside the filter cover, an upstream first filter and a downstream second filter are stacked vertically.
The first filter is a filter paper filter,
The second filter is a non-woven filter,
The air filter is provided in an upper cover of the portable work machine, and is provided with a filter chamber surrounded by the cover on the upstream side of the air filter and provided with an inflow port.
The inlet is an outlet of a cylindrical cyclonic separation device arranged upstream of the air filter and opens in the direction opposite to the air filter.

That is, normally, the air coming out from the inlet of the filter chamber goes straight toward the inlet of the air filter having a lower pressure in the cover, so that the air is difficult to diffuse and it is difficult for dust and water droplets to fall by gravity. . However, according to the above configuration, the direction of the inlet of the filter chamber formed by the outlet of the cylindrical cyclonic separator disposed upstream of the air filter is directed to the opposite side of the air filter. The outflow air collides with the inner surface of the cover that forms the space toward which the flow velocity decreases. This ensures that, to improve the ability to capture dust.

In a sixth invention, in any one of the first to fifth inventions,
A centrifugal fan driven by the engine to suck in and send out air;
A main passage that is formed in a housing space of the centrifugal fan and sends out cooling air containing dust pressed against the radially outer inner circumferential surface by the centrifugal fan, and disposed at a position shifted from the main passage, to the air filter side A branch air intake for sending air containing less dust than the main passage;
A cylindrical cyclonic separator disposed upstream of the air filter;
An introduction passage extending from the branch air intake to the cyclone separator ,
The introduction passage is provided so as to extend at an acute angle with respect to the cyclonic separator .

According to the above configuration, most dust having relatively large particles is removed before reaching the air filter, so that the life of the air filter is extended and the maintenance cycle is extended. In addition, since the introduction passage is provided to extend at an acute angle with respect to the cyclonic separation device, the passage area is smaller than when the air is flown straight from the tangential direction when air with reduced dust flows by the action of the centrifugal fan. Even if it is wide, it is difficult to inhibit the generation of swirl. In addition, since the cyclonic separator is closer to the center line of the centrifugal fan by setting an acute angle, the portable work machine can have a compact structure.

In a seventh invention, in any one of the first to sixth inventions,
The portable working machine, Ri engine cutter der,
The filter cover, that is provided inside the cover on the upper side of the engine in the body casing between the front handle and the rear handle.

  According to said structure, since stone materials, such as concrete, are cut | disconnected, the fine dust which generate | occur | produces at that time can also be collected reliably, and the performance of an engine does not deteriorate.

  As described above, according to the present invention, the filter paper filter and the nonwoven fabric filter are arranged in series in the filter cover in the intake passage of the engine, so that the dust collecting ability of the air filter is improved, and the engine It is possible to improve the durability of the engine by preventing dust and water from entering the intake air.

1 is a perspective view showing the entirety of a portable work machine according to an embodiment of the present invention. It is the side view which made the centrifugal fan and its periphery visible. It is the front view which made the centrifugal fan, the main channel | path, and its periphery visible. It is the side view which made the introduction channel | path and its periphery visible. It is the expanded side view which made the introduction channel | path and its periphery visible. FIG. 3 is an enlarged plan view showing a stagnation space, a cyclonic separation device, and its periphery. It is the enlarged front view which made the main channel | path, an introduction channel | path, a cyclonic separator, and its periphery visible. It is the perspective view which cut | disconnected the upper side of the engine cutter so that the inside could be seen. It is the expansion perspective view which cut | disconnected the air filter so that the inside could be seen. It is the perspective view which made the flow of the air which flows into an air filter visible. It is a perspective view which expands and shows a cyclone casing. It is a side view which shows the flow of the air in a fluctuation | variation absorption space.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

-Engine cutter configuration-
FIG. 1 shows an engine cutter 1 as a portable work machine according to an embodiment of the present invention. The engine cutter 1 has an engine 2 as a power source. The engine 2 is housed in a main casing 3 and can drive concrete to cut concrete or the like by driving the disk-shaped blade 4. A front handle 5 is provided on the front side of the main casing 3, and a rear handle 6 is provided on the rear side.

  The main casing 3 includes a plurality of members, and includes a lower casing 3 b that is disposed mainly on the side of the engine 2 and has an air introduction opening 3 a, and an upper casing 3 c provided on the upper side of the engine 2.

  As shown in FIG. 2, the engine cutter 1 includes a centrifugal fan 7 that is driven by the engine 2 to suck and send air. The rotating shaft 7 a of the centrifugal fan 7 extends in the width direction of the engine cutter 1 as with the rotating shaft of the engine 2. The centrifugal fan 7 has a plurality of blades 7b, and air containing dust is taken in from the air introduction opening 3a of the lower casing 3b by the rotation of the plurality of blades 7b. The air is accelerated in a housing space 8 surrounded by a fan casing 8a and a lower casing 3b covering the outside of the centrifugal fan 7 by a plurality of blades 7b and a crankcase of the engine 2 inside, and is radially outward of the fan casing 8a. Cooling air for cooling the engine 2 including dust pressed against the inner peripheral surface 8b is sent through the main passage 9 to the cylinder portion 2a, which is a main heat generating portion of the engine 2, as indicated by an arrow. Regarding the cylinder part 2a, cooling is given priority and dust and water droplets may be included.

  As shown in FIGS. 3 and 4, at a position shifted from the main passage 9 to the side closer to the centrifugal fan 7 (the side far from the radially outer inner peripheral surface 8b), the main passage toward the air filter 18 described later is provided. A branch air intake 10 is formed through which air containing less than 9 dust is sent.

  Further, a cyclonic separator 11 having a circular cross section as shown in FIG. 7 and the like is provided upstream of the air filter 18. The cyclonic separator 11 is disposed above the centrifugal fan 7 and extends in the axial direction of the rotating shaft 7a of the centrifugal fan 7 (the width direction of the engine cutter 1). This makes it possible to effectively remove dust and water droplets even in the smallest possible space while preventing the engine cutter 1 from increasing in size.

  As shown in FIGS. 4 and 5, an introduction passage 12 extends from the branch air intake 10 to the cyclone separator 11. The introduction passage 12 has an upstream portion formed by a portion surrounded by a rib-like wall portion on the inner side of the lower casing 3b and on the outer side of the upper portion of the fan casing 8a. The connection opening 12c (opens in the upper casing 3c, see FIG. 6). ), The remaining downstream portion is connected to the inlet of the cyclonic separator 11, and is S-shaped when viewed from the axial direction of the centrifugal fan 7 (the width direction of the engine cutter 1) (as shown in FIG. 5). When viewed from the outside of the machine, it is bent in an inverted S shape. From another viewpoint, the introduction passage 12 extends in the tangential direction (left and right direction in FIG. 5) of the cyclone separator 11 when viewed from the axial direction of the cyclone separator 11 and is continuous with the cyclone separator 11. A straight portion 12a (indicated by a range A in FIG. 5), and a curved portion 12b that is continuous with the straight portion 12a and curves so as to wrap around. Further, when viewed from the axial direction of the cyclonic separator 11, the introduction passage 12 extends in an acute angle α direction with respect to the inlet to the cyclonic separator 11 with respect to the tangential direction of the inlet. Specifically, in the example of FIG. 5, the introduction passage 12 is below (upstream) the connection opening 12 c with respect to the straight portion 12 a extending in the tangential direction of the circular inlet of the cyclonic separator 11. The direction of the part is an acute angle α.

  As shown in FIGS. 5 to 7, in front of the cyclonic separation device 11 in the introduction passage 12, a connection opening portion 12 c is used as an inlet in a passage portion formed by the curved portion 12 b and the straight portion 12 a. A surplus space 13 in which at least a part of the air introduced from the connection opening 12c flows, which is a portion where the area expands, is formed. The surplus space 13 is a cyclone with respect to the inlet of the cyclonic separation device 11 from the outer side (right side in FIG. 6) of the connection opening 12c in the passage portion constituted by the connection opening 12c, the curved portion 12b, and the straight portion 12a. It is formed by swelling on the opposite side (right side in FIG. 6) of the axial separator 11. Specifically, the surplus space 13 is provided inside a cyclone casing 15 (see FIG. 11) for forming the cyclonic separator 11 that covers the connection opening 12c of the introduction passage 12 formed in the upper casing 3c. Is formed. In this embodiment, the upper part of the cyclonic separator 11 is formed by the cyclone casing 15 and the lower part is formed by the upper casing 3c, and the cyclonic separator 11 is formed by combining these two parts. The cyclone casing 15 is made of, for example, a resin molded product that can mold a complicated shape. In this surplus space 13, the starting point of the swirling flow in the cyclone separator 11 is generated.

  As shown in FIGS. 7 to 9, an outlet side tubular portion 16 having an inner diameter smaller than the inner diameter of the cyclone separator 11 is provided on the front side of the cyclone separator 11. The outlet-side cylindrical portion 16 is formed integrally with the cyclone casing 15 when the cyclone casing 15 is molded, for example, with a circular cross section and concentric with the cyclone separator 11. As shown in FIGS. 6 and 7, the inner peripheral surface 11 a of the cyclonic separator 11 located radially outside the outlet-side cylindrical portion 16 has a cylinder portion 2 a on the downstream side of the lower main passage 9. A drawing through-hole 17 (opened in the upper casing 3c) communicating with the cooling fin outlet side 2b of the cylinder fin is opened. At least a part of the air pressed from the drawing through hole 17 to the radially outer peripheral surface of the cyclonic separating device 11 is drawn to the cooling air outlet side 2b side of the cylinder fin of the cylinder part 2a. Yes. This utilizes the so-called ejector effect in which air is sucked from the lead-in through hole 17 because the flow velocity and flow rate of the cooling air on the outlet side 2b of the cooling air of the cylinder fin of the cylinder portion 2a are large. For this reason, the lead-in through-hole 17 is set to an appropriate size that is neither too large nor too small. As shown in FIGS. 2 and 4, a muffler 2c is provided in front of the cylinder portion 2a.

  As shown in FIGS. 9 and 10, the air filter 18 is provided in a space (a filter chamber described later) surrounded by the upper casing 3 c on the upper side of the engine cutter 1 and the top cover 3 d. The air filter 18 has a columnar shape, for example, and is covered with a cylindrical filter cover 19. In the present embodiment, the filter cover 19 is integrally formed with the upper casing 3c. However, the present invention is not limited to this, and for example, the filter cover 19 may be airtightly attached as separate components. The inlet of the air filter 18 is disposed above the outlet of the cyclonic separation device 11 (the outlet of the outlet side cylindrical portion 16, that is, the inlet of the filter chamber) in a side view. The air filter 18 is configured by stacking an upstream first filter 18a and a downstream second filter 18b. The first filter 18a is a filter paper filter, and the second filter 18b is a nonwoven fabric filter. The first filter 18a is a cylindrical filter paper filter, and the mesh of the filter paper is, for example, about 20 to 30 μm. Since concrete dust also includes particles of 1 μm or less, such fine dust particles only work with contact filtration that is trapped when colliding with and contacting the lattice in the filter. Sufficient collection ability cannot be obtained. The second filter 18b is a disk-shaped nonwoven fabric filter. The first filter 18a and the second filter 18b are accommodated in a cylindrical filter cover 19 with a gap 18c between them. The first filter 18a may have a rectangular column shape, and the second filter may have a square plate shape. Accordingly, the filter cover 19 may also be a square cylinder.

  As shown in FIG. 11, a guide portion 20 extending in the circumferential direction of the swirling flow in the cyclonic separation device 11 is formed in the space from the outlet of the outlet side tubular portion 16 toward the air filter 18. . As shown in FIG. 10, the front end (outflow portion) of the guide portion 20 faces the side opposite to the air filter 18 (in front of the engine cutter 1).

  In addition, the space surrounded by the upper side of the upper casing 3c and the inner surface of the top cover 3d from the outlet of the outlet-side cylindrical portion 16 toward the air filter 18 is a filter chamber that absorbs changes in flow velocity and pressure in this space. The fluctuation absorbing space 21 is configured. As shown in FIG. 12, the bottom surface forming the fluctuation absorbing space 21 is inclined downward from the lower end of the filter cover 19 toward the rear of the work machine (on the rear handle 6 side). Due to this inclined shape, a space is spread downward at the lower end portion of the filter cover 19 in the bottom surface of the upper casing 3c in the range B in FIG. In addition, gaps are also secured between the top cover 3d in the front, rear, left, and right directions of the outlet side tubular portion 16 and the filter cover 19 on the opposite side. Part of.

  The change in flow velocity and pressure here means that the flow velocity and pressure in the upstream path of the air filter 18 fluctuate depending on the rotational speed of the engine 2 and the centrifugal fan 7. In the engine 2, when the rotational speed increases, the intake flow velocity and the intake negative pressure increase. And especially in this embodiment, the air discharged from the centrifugal fan 7 is sent to the air filter 18 side from the branch air intake 10, and the air from such a centrifugal fan 7 increases as the number of revolutions increases. The flow rate and pressure increase. These fluctuations are absorbed by the fluctuation absorption space 21.

-Air flow toward the air filter-
The flow of air toward the air filter 18 in the engine cutter 1 configured as described above will be described in detail with reference to the drawings.

  When cutting a concrete lump or the like with the engine cutter 1 of the present embodiment, the engine 2 is started, the blade 4 is rotated, and the blade 4 is cut while being pushed into the concrete lump. At that time, concrete dust is generated. When cutting a water pipe, the water adhering to the water pipe may be blown up. During the operation of the engine 2, it is necessary to cool the heat generating part such as the cylinder part 2 a and to send air without dust into the combustion chamber of the engine 2.

  When the centrifugal fan 7 is rotated by starting the engine 2, air is sucked from the air introduction opening 3a by the action of the blade 7b. At the time of cutting, a large amount of concrete dust is sucked.

  As shown in FIGS. 2 and 3, the cooling air containing dust pressed against the radially outer peripheral surface 8b by the centrifugal fan 7 is sent to the cylinder portion 2a and the like through the main passage 9, and the cylinder portion 2a and the like. The heat generating part is cooled. The air passing through the main passage 9 is discharged from the opposite side (left side in FIG. 3) after cooling the heat generating portion.

  As shown in FIGS. 3 and 4, from the branch air intake 10 located at a position shifted from the main passage 9 to the side closer to the centrifugal fan 7 (the side far from the radially outer inner peripheral surface 8 b) than the main passage 9. Also, air with less dust flows into the introduction passage 12. At this stage, dust having a large mass is removed by the action of the centrifugal fan 7, but dust having a relatively small mass is not removed.

  As shown in FIG. 5, when air is sent from the introduction passage 12 to the cyclone separator 11, a swirl flow is caused in the cyclone separator 11 by sending air from the tangential direction (right side in FIG. 5). be able to. Here, if the size of the inlet passage (corresponding to the straight portion 12a) connected to the cyclone type separation device 11 is made too large by simply feeding straight air from the tangential direction as in the prior art, the swirling flow is hindered. . However, in the present embodiment, when the air whose dust is reduced by the action of the centrifugal fan 7 flows in, the air that has circulated around the curved portion 12b smoothly flows into the straight portion 12a. By providing the straight portion 12a, the introduction passage 12 can be expanded outward in the radial direction of the cyclonic separation device 11 as compared with the curved introduction passage 12 without the straight portion 12a. As a result, the swirling flow is inhibited. Without increasing the passage area. Thereby, since air can be sent in more smoothly compared with a thing with a small passage area, dust is effectively isolate | separated within the cyclone type | mold separation apparatus 11. FIG.

  Moreover, in this embodiment, since the introduction passage 12 is provided so as to extend at an acute angle α with respect to the cyclonic separation device 11, when the air reduced in dust by the action of the centrifugal fan 7 flows in, it is simply tangential. Even if the passage area is increased, it is difficult to inhibit the generation of swirling flow as compared with the case of flowing straight from the direction. In addition, by setting the acute angle α, the cyclonic separator 11 can be moved to the right side of FIG. 5 and is closer to the center line of the centrifugal fan 7 (that is, the cylinder axis of the cylinder portion 2a). A compact structure can be obtained.

  Then, as shown in FIGS. 5 to 7, when the air whose dust is reduced by the action of the centrifugal fan 7 flows into the cyclone separator 11 from the connection opening 12 c of the introduction passage 12, the cyclone separator 11. In the surplus space 13 provided in front of, the base point of the swirl flow generated in the subsequent cyclone separator 11 is generated. As a result, a swirl flow in the cyclone separator 11 is generated at an earlier stage than in the case where there is no surplus space 13, and air smoothly swirls in the cyclone separator 11 thereafter. Thus, since the surplus space 13 plays a role like a space for running a swirling flow, an appropriate number of turns can be obtained at a short distance. Thereby, dust is effectively separated in the cyclonic separator 11.

  As shown in FIG. 7, in the cyclone separator 11, dust moves toward the radially outer inner peripheral surface (the cyclone inner peripheral surface 11 a) of the cyclone separator 11 by the centrifugal force due to the swirling flow, and the outlet Air with less dust flows into the side cylindrical portion 16. The air containing a lot of dust in the vicinity of the inner peripheral surface 11a of the cyclone is drawn to the air flowing to the outlet side 2b of the cooling air of the cylinder fin of the cylinder portion 2a flowing at high speed and discharged from the drawing through hole 17 (so-called Ejector effect). By utilizing the pull-in by the cooling air outlet side 2b of the cylinder fin of the cylinder part 2a, a dedicated passage part is not required to use the suction force of the inlet part of the centrifugal fan 7 as in the prior art. The number of parts can be reduced and the entire product can be downsized.

    As shown in FIG. 9, normally, the air exiting from the cyclone separator 11 goes straight toward the inlet of the air filter 18 having a lower pressure, so that the air is not easily diffused, and dust and water droplets fall by gravity. It is difficult. However, according to this embodiment, as shown in FIGS. 10 and 11, the tip of the guide portion 20 (corresponding to the outflow portion and the inlet of the filter chamber) faces the opposite side of the air filter 18. The air sent from the cyclonic separation device 11 collides with the inner surface of the top casing 3c and the top cover 3d that forms the fluctuation absorbing space 21 (corresponding to the filter chamber) toward 18 to reduce the flow velocity and change It diffuses in the absorption space 21. This reduces the flow of air flowing into the filter, reducing the mechanical wear of the filter due to dust and the permeation of fine dust particles due to high-speed flow. And water droplets are easily dropped by gravity, and dust and water droplets are prevented from reaching the inlet of the air filter 18. Of the dust and water droplets that could not be separated by the cyclonic separator 11, the relatively heavy dust and water droplets flow out from the outlet of the guide portion 20 and collide with the inner surfaces of the upper casing 3c and the top cover 3d. In this case, since it is peeled off from the air flow and then deposited on the bottom surface on the front side of the upper casing 3c due to gravity drop, the cyclone casing 15 is again brought into the inlet of the air filter 18 by the air flow. Acts as a weir against a movement that tries to rise to the side.

  Further, by providing the fluctuation absorbing space 21 composed of a relatively wide space in front of the air filter 18, when the air that has come out of the cyclone type separation device 11 flows into the fluctuation absorbing space 21 that is much wider than that, Flow rate and pressure are reduced. For this reason, the speed of the dust impinging on the air filter 18 is reduced, the mechanical wear of the air filter 18 is reduced, and transmission due to the coarse dust particles being pushed into the meshes of the filter by high pressure, And the permeation | transmission of the fine dust particle | grains by a high-speed flow is reduced. This is not the case when the high pressure air flow sent out from the branch air intake 10 by the centrifugal fan 7 is sent to the air filter side as well as the intake negative pressure of the engine as in this embodiment. Even more effectively, high pressure can be effectively prevented from being applied to the air filter 18. In addition, heavy dust and water droplets (mist) can be dropped by gravity before the air reaches the inlet of the air filter 18. Thereby, it is possible to prevent foreign matters such as dust and water droplets from reaching the air filter. By doing so, it is not necessary to provide a pre-filter such as a sponge in front of the air filter 18, and complicated maintenance work can be avoided.

  Furthermore, as shown in FIG. 12, the bottom surface forming the fluctuation absorbing space 21 is inclined downward from the lower end of the filter cover 19 toward the rear of the work machine (on the rear handle 6 side). Since a gap is secured not only between the upper portion serving as the inlet of the air filter 18 but also outside the cylindrical peripheral surface of the filter cover 19 between the top cover 3d and the top cover 3d, the filter cover for fixing the air filter 18 A flow of air is also generated below and around 19 so that heavy dust and water droplets (fog) are more effectively dropped by gravity drop so that they do not reach the inlet of the air filter 18 above them. it can. Further, the dust that has flowed into the space in front of the air filter 18 can be deposited on the entire bottom surface forming the variable absorption space 21 including the region extending downward, and the dust can be deposited at the inlet of the air filter 18. Since the amount of deposition can be reduced, the maintenance period becomes longer.

  In addition, since the inlet of the air filter 18 is above the cyclone type separation device 11, the fluctuation absorption space 21 extends in the vertical direction so that heavy dust and water droplets (mist) do not reach the air filter 18 due to gravity drop. can do.

  Furthermore, by expanding the fluctuation absorbing space 21 below the filter cover 19 that fixes the air filter 18, heavy dust and water droplets (fog) are more effectively dropped by gravity drop, and the air filter 18 located above the dust filter and the water drop 18. Can be prevented from reaching the entrance.

  Thus, although only the 1st filter 18a which consists of a filter paper filter cannot capture fine dust enough, according to this embodiment, the 1st filter 18a cannot capture the fine dust which could not be captured by the 2nd nonwoven fabric filter. It can be captured by the filter 18b. Further, compared to the case of only the first filter 18a, since the second filter 18b is provided, the ventilation resistance is increased, the region where the flow velocity is locally large is reduced, and the dust transmitted through the filter paper by the high-speed fluid is reduced. Further, even if the mixed fuel blows back, it adheres to the second filter 18b on the side close to the engine 2, so that gasoline does not reach the first filter 18a, and the filter paper and adhesive of the first filter 18a deteriorate. The risk of tearing the filter paper filter and leaking dust decreases. Further, when lubricating oil by blowing back adheres to and accumulates on the second filter 18b, the second filter 18b is rather wetted and the ability to collect 1 μm-sized fine dust is secured. In this way, the first filter 18a and the second filter 18b complement each other's collection ability and exhibit a synergistic effect.

  Even if there is a local concentration of negative pressure in the first filter 18a, air moves easily in the gap 18c, so that it is easy to disperse. Since the first filter 18a and the second filter 18b have the same cross section, this effect is easily exhibited. Further, since there is a gap 18c, fuel and lubricating oil adhering to the second filter 18b do not infiltrate the first filter 18a.

  Furthermore, since most of the dust having relatively large particles has been removed by the device described above until reaching the air filter 18, the life of the air filter 18 is extended and the maintenance cycle is lengthened.

  Even when a stone material such as concrete is cut, the fine dust generated at that time can be reliably collected, so that the performance of the engine 2 does not deteriorate.

  Furthermore, in the durability test (acceleration test) actually performed in a high-concentration dust environment, the life of 30 hours with only the first filter 18a becomes 90 hours with the addition of the second filter 18b. It was found that the service life was extended.

  On the other hand, in the state of only the second filter 18b (the state in which the first filter 18a is broken and only the second filter 18b is functioning), not only fine dust but also coarse dust has entered the engine side. I understood it.

  From the above, even if only one each of the first filter 18a or the second filter 18b is disposed, it is not possible to prevent dust from entering the engine side, and the first filter 18a and the second filter 18b It was found that the effect of preventing the intrusion of dust can be obtained only when both are provided.

  Therefore, according to the engine cutter 1 according to the embodiment of the present invention, the first filter 18a and the second filter 18b are provided in the filter cover 19 in the intake passage of the engine 2 that operates with a mixed fuel of fuel and lubricating oil as a power source. Are arranged in series, the dust collecting ability of the air filter 18 can be improved, dust and water can be prevented from being mixed into the intake air of the engine 2, and the durability of the engine 2 can be improved.

(Other embodiments)
The present invention may be configured as follows with respect to the above embodiment.

  That is, in the above embodiment, the example in which the variable absorption space 21, the cyclonic separation device 11, the surplus space 13, and the like are provided upstream of the air filter 18 has been described. The air filter 18 can exhibit the effect.

  Moreover, although the said embodiment demonstrated the portable work machine which uses the engine 2 (what is called a mixed lubrication engine) which operate | moves with the mixed fuel of fuel and lubricating oil as a power source, this invention is not limited to this. Even in a portable working machine that uses an engine that is supplied with only fuel (so-called pure gasoline engine) as a power source, the second filter 18b (nonwoven fabric filter) and the gap 18c are provided, so that the second operation caused by blow-back by the fuel is provided. The effect of preventing the filter paper and adhesive of the 1 filter 18a (filter paper filter) from deteriorating can be obtained.

  Moreover, although the said embodiment demonstrated what mixed fuel was supplied to the engine 2 using a carburetor, in this invention, it is not limited by the supply method of mixed fuel. Specifically, the fuel mixture is stored in a fuel tank and the mixed fuel is supplied to the carburetor. In addition, the fuel and lubricating oil are stored in separate storage tanks. The carburetor may be separately supplied. Whichever supply method is used, if lubricating oil is contained in the blowback from the engine, it is possible to obtain an effect of improving the collection capability of the fine dust by the wetting of the second filter 18b (nonwoven fabric).

  Moreover, in the said embodiment, although the example of the engine cutter 1 was shown as a portable working machine, the blower which is a blower for cleaning of hedge trimmers which are pruning machines, such as hedges, and dead leaves may be used. Since these are also used in an environment where a large amount of dust (sand dust) has already accumulated or adhered to the work place (road) or work target (plants) before work, the effect of the present invention is exhibited.

  In addition, in the said embodiment, although the drawing-in through-hole 17 is provided in the position of the exit side 2b of the cooling air of the cylinder fin of the cylinder part 2a, this invention is not limited to this. The position of the lead-in through hole can be the above ejector effect as long as high-speed cooling air from the centrifugal fan 7 flows (in the vicinity of the heat generating part). If the muffler 2c of the engine 2 has a structure in which the cooling air from the centrifugal fan 7 is applied to the muffler 2c, the drawing through hole may be provided in the path through which the cooling air near the muffler 2c passes. . As described above, when the drawing through hole is provided in the vicinity of the muffler 2c, the cooling air flows out of the working machine from the left side (right side of the working machine) in the drawing as shown in FIG. 3 (in this case) In addition to the cooling air hitting the outer wall of the muffler 2c on the cylinder part 2a side, the cooling air is applied to the upper part of the muffler 2c, and then the cooling air flows out from the front side of the working machine (left side in FIG. 4). Each of them may be provided with a through hole at a position where the cooling air flows.

  In addition, the above embodiment is an essentially preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or a use.

  As described above, the present invention is useful for portable work machines such as engine cutters.

1 Engine cutter (portable work machine)
2 Engine
2a Cylinder part
2b Cooling air outlet side of cylinder fin of cylinder part
2c muffler
3 Body casing
3a Air introduction opening
3b Lower casing
3c Upper casing
3d top cover
4 blades
5 Front handle
6 Rear handle
7 Centrifugal fan
7a Rotating shaft
7b feather
8 accommodation space
8a Fan casing
8b Radial outer side inner peripheral surface
9 Main passage
10 Branch air intake
11 Cyclone separator
11a Cyclone inner peripheral surface
12 Introduction passage
12a Straight section
12b Curved part
12c Connection opening
13 Extra space
15,115 Cyclone casing
16 Outlet side cylindrical part
17 Lead-through hole
18 Air filter
18a first filter
18b Second filter
18c gap
19 Filter cover
20 Guide section
21 Fluctuation absorption space (filter room)

Claims (7)

In a portable work machine equipped with an air filter that sends fresh air to the engine that is the power source,
A filter cover for housing the air filter;
In the filter cover, a first filter on the upstream side and a second filter on the downstream side are stacked,
The first filter is a columnar filter paper filter,
The second filter, Ri plate-like non-woven filter der,
The first filter and the second filter, the portable working machine, characterized that you have been accommodated alongside in series into the cylindrical of the filter cover while keeping a clearance from each other in the air flow direction. The portable work machine according to claim 1, wherein
The air is configured to flow linearly in the order of the first filter, the gap, and the second filter from the inlet on one end side of the filter cover to the outlet on the other end side. A portable work machine. The portable work machine according to claim 1 or 2,
The portable work machine, wherein the first filter and the second filter have the same cross-section cut by a plane perpendicular to the air flow direction . In a portable work machine equipped with an air filter that sends fresh air to the engine that is the power source,
A cylindrical filter cover for housing the air filter;
Inside the filter cover, an upstream first filter and a downstream second filter are stacked vertically.
The first filter is a filter paper filter,
The second filter is a non-woven filter,
The air filter is provided on the upper side of the portable work machine, and includes a filter chamber provided with an inlet on the upstream side of the air filter,
The space in the filter chamber from the inlet to the inlet opening of the filter cover constitutes a variable absorption space that absorbs changes in flow velocity and pressure in the space .
A portable work machine , wherein a bottom surface forming the fluctuation absorbing space is inclined downward from a lower end portion of the filter cover toward an opposite side of the inflow port . In a portable work machine equipped with an air filter that sends fresh air to the engine that is the power source,
A cylindrical filter cover for housing the air filter;
Inside the filter cover, an upstream first filter and a downstream second filter are stacked vertically.
The first filter is a filter paper filter,
The second filter is a non-woven filter,
The air filter is provided in an upper cover of the portable work machine, and is provided with a filter chamber surrounded by the cover on the upstream side of the air filter and provided with an inflow port.
The portable working machine , wherein the inflow port is an outlet of a cylindrical cyclonic separation device disposed upstream of the air filter and opens in a direction opposite to the air filter. The portable work machine according to any one of claims 1 to 5,
A centrifugal fan driven by the engine to suck in and send out air;
A main passage that is formed in the housing space of the centrifugal fan and sends out cooling air containing dust pressed against the radially outer inner circumferential surface by the centrifugal fan, and is disposed at a position shifted from the main passage, to the air filter side A branch air intake for sending air containing less dust than the main passage;
A cylindrical cyclonic separator disposed upstream of the air filter;
An introduction passage extending from the branch air intake to the cyclone separator ,
The portable work machine , wherein the introduction passage is provided to extend at an acute angle with respect to the cyclonic separation device . The portable work machine according to any one of claims 1 to 6,
The portable working machine, Ri engine cutter der,
The filter cover, the front handle and portable working machine, characterized that you have provided within the cover on the upper side of the engine in the body casing between the rear handle.

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