JP2017101606A - Air cleaner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively suppress or reduce failure or trouble resulting from mixed fuel blown back from a carburetor, to thereby prolong a service life of a filter and reduce maintenance frequency of the filter.SOLUTION: An air cleaner includes: a fuel storage part 30 formed around a cleaner outlet 20 provided on a cleaner bottom wall 15A positioned on a carburetor 65 side, and configured to collect and store mixed fuel blown back from the carburetor 65; and a slit-like return passage 35 that is formed between plate-like ribs 33, 34 erected side by side on the cleaner bottom wall 15A in order to recirculate mixed fuel stored in the fuel storage part 30 to the carburetor 65 side with surface tension and intake negative pressure, of which a one-end side opening communicates with the fuel storage part 30, and the other-end side opening communicates with the cleaner outlet 20.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an air cleaner disposed immediately upstream of a carburetor in an intake system of an engine, and particularly suppresses or reduces problems and troubles caused by mixed fuel (gasoline and lubricating oil) blown back from the carburetor. It is related with the air cleaner made to obtain.

  For example, in a portable power working machine such as a chain saw or a brush cutter, a small air-cooled internal combustion engine having a displacement of about 25 to 100 cc is usually used as a power source for driving a working unit such as a saw chain in a main body housing. A two-cycle gasoline engine is mounted, and a carburetor as a fuel supply / metering means is provided in the intake system of the engine. An air cleaner is provided to remove and clean.

  Hereinafter, a conventional example of the above air cleaner will be described with reference to FIG. 4 showing a rear part of a chain saw and a part of a reverse scavenging type two-cycle gasoline engine having four scavenging ports mounted on the left and right. .

  In the illustrated conventional chain saw 50, a top handle 54 incorporating a throttle lock lever and a throttle trigger is disposed across the upper surface and the rear of the main body housing 52, and is driven by the engine 60 in the main body housing 52. A cooling fan (not shown) is provided, and a part of the air sucked into the main body housing 52 by this cooling fan is sent to the top handle 54 and the air cleaner 10 ′ provided at the rear part of the main body housing 52 and vaporized. The air is sucked into the cylinder 62 of the engine 60 through the container 65.

  The engine 60 is mounted horizontally in the main body housing 52 with its intake port 63 facing upward and the head (combustion chamber) 64 facing the rear of the fuselage. The synthetic rubber is upstream of the intake port 63. The vaporizer 65 is connected via a vibration-absorbing vent pipe 66 made of a material, and an air cleaner 10 ′ is connected immediately upstream of the vaporizer 65.

  The air cleaner 10 'includes a synthetic resin case 11 having a bottom wall 15 [a bottom wall 15A on the vaporizer 65 side (upper side) and a bottom wall 15B on the cleaner inlet 16 side (lower side)] and an outer peripheral side wall 15C. A thick plate-like filter (filtering element) 12 that covers the upper surface opening of the cover 11, a synthetic resin cover 13 that covers the filter 12 so as to be sandwiched between the case 11, and the cover. 13, a screw member 18 screwed into a female screw portion 17 formed around the boundary between the vaporizer-side bottom wall 15 </ b> A and the cleaner inlet-side bottom wall 15 </ b> B in the case 11. If the cover is loosened, the cover 13 and the filter 12 can be removed.

  Further, as shown in FIG. 5, the case 11 portion of the air cleaner 10 ′ is connected to the vaporizer side bottom wall 15 </ b> A of the case 11 so that the cleaner outlet is connected to the suction port 67 a of the internal passage 67 in the vaporizer 65. 20 is provided. The cleaner outlet 20 has an upper end portion (boss portion 20a) protruding slightly above the upper surface of the bottom wall 15A. On the bottom wall 15A, a sheet metal blow back guiding member 19 is arranged to prevent the mixed fuel (described later) blown back from the vaporizer 65 from being directed toward the filter 12 side.

  As shown in the plan view of the attached state in FIG. 6, the blow-back guiding member 19 includes an inverted lip groove-shaped bent plate portion 19A straddling the center of the cleaner outlet 20, and the bent plate portion 19A. It comprises a crescent-shaped plate portion 19B that is bent slightly downward from the upper plate portion 19a toward the female screw portion 17, and is a screw that bends outward at the lower ends of both side plate portions 19b and 19b of the bent plate portion 19A. Stop plate portions 19c and 19c are provided. The set screw 22 is screwed into the carburetor 65 through the through holes 19d provided in the screw fixing plate portions 19c, 19c and the insertion holes 29, 29 with the boss portions 29a provided in the bottom wall 15A of the case 11. The blow back guiding member 19 and the case 11 are fastened and fixed to the vaporizer 65 together.

  In addition, rising plate portions 27 and 28 are provided on the cleaner inlet bottom wall 15B of the case 11 in order to define a fuel reservoir 25 that collects and stores the fuel blown back from the vaporizer 65.

Japanese Utility Model Publication No. 38-21007 Japanese Utility Model Publication No. 63-75559 Japanese Patent No. 5684445

  By the way, in the intake system of the engine 60 in the chain saw 50 or the like as described above, if no measures are taken, the mixed fuel (gasoline and lubricating oil) once atomized by the carburetor 65 due to blow-back from the intake port 63 is taken. Oil) is blown back into the case 11 through the cleaner outlet 20. This blown-back flow is indicated by broken line arrows in FIG. The mixed fuel blown back into the case 11 through the cleaner outlet 20 is guided to the blow-back guiding member 19 (broken arrow in FIG. 4) and travels along the inner wall surface (the outer peripheral side wall 15C and the bottom wall 15) of the case 11. Then, the fuel is collected and stored in the fuel reservoir 25, but a part of the fuel adheres to the filter 12 as it is. In addition, a part of the stored mixed fuel is sucked to the cleaner outlet 20 side by the intake negative pressure at the time of inhalation after being blown back, and is returned to the carburetor 65, but a part thereof remains in the fuel reservoir 25 and remains in the fuel reservoir. It overflows from the portion 25 and adheres to the filter 12.

  As for the mixed fuel adhering to the filter 12, only gasoline is vaporized, and only the oil component remains in the case 11 and the filter 12. As a result, the ventilation resistance of the filter 12 increases (intake air amount decreases), and the nozzle of the carburetor 65. The boost pressure applied increases, the fuel flow rate increases, the air-fuel mixture used for combustion becomes excessively rich, the output decreases, the workability deteriorates, and the operator frequently performs maintenance (replacement etc.) of the filter 12 ). If the maintenance of the filter 12 is neglected, the oil saturated with the case 11 not only stains the machine body but also causes soil contamination (such as a brush cutter is disliked in particular in rice processing).

  In order to suppress or reduce the problems and troubles caused by the mixed fuel blown back from the carburetor as described above, the mixed fuel blown back from the carburetor is collected and stored, as seen in, for example, Patent Documents 1 and 2, etc. It has been proposed to provide a fuel reservoir and a return flow path for returning the fuel accumulated in the fuel reservoir to the carburetor side using intake negative pressure. However, as described in the above-mentioned patent document, if the return flow path is constituted by a pipe line (pipe) that connects the fuel reservoir of the case and the vaporizer through the outside of the air cleaner, the pipe inevitably. The length of the path becomes longer, and it is possible that the time for the fuel accumulated in the fuel reservoir to reach the carburetor side will be longer (slower), and the pipe line due to fuel mixing in the reverse direction, etc. There is a possibility that air will accumulate in the pipe (clogged pipes), and that alone is especially likely to cause a large change in the attitude of the fuselage (engine / air cleaner) (easy to tilt, tip over, etc.) In the type work machine, the above problems and troubles cannot be solved sufficiently.

  For example, in Patent Document 3, a plurality of the return passages are provided radially around the cleaner outlet, and the return passages are provided with a sloped flow installed on the bottom wall of the cleaner. Although it has been proposed to include the path forming plate portion, even in such a conventional technique, there is still a problem that the arrangement configuration of the flow path forming plate portion constituting the return flow path is difficult, There is a problem that the fuel accumulated in the section cannot be efficiently recirculated to the carburetor side through the cleaner outlet.

  The present invention has been made in view of the above circumstances, and the object of the present invention is to be able to effectively suppress or reduce problems and troubles caused by the mixed fuel blown back from the vaporizer with a simple configuration. Another object of the present invention is to provide an air cleaner capable of extending the filter life and reducing the maintenance frequency.

  In order to achieve the above object, the air cleaner according to the present invention is basically disposed immediately upstream of the carburetor in the intake system of the engine, and is provided on the bottom wall of the cleaner located on the carburetor side. A fuel reservoir that collects and stores the mixed fuel blown back from the carburetor, and the mixed fuel that accumulates in the fuel reservoir using surface tension and intake negative pressure. One end side opening communicates with the fuel reservoir, and the other end side opening is provided with a slit-like return passage communicating with the cleaner outlet so as to return to the vaporizer side.

  In a preferred embodiment, the return passage is formed between plate-like ribs standing upright along the bottom wall of the cleaner.

  In a further preferred aspect, the plate-like rib is integrally formed with the cleaner bottom wall.

  In another preferred embodiment, a plurality of plate-like ribs constituting the return passage are arranged in parallel.

  In another preferred embodiment, a blow-back guide member that guides the mixed fuel blown back into the air cleaner through the cleaner outlet so as to go to the fuel reservoir side instead of the filter side, and the cleaner outlet and the return passage are connected to each other. A predetermined distance is provided so as to cover and from the cleaner outlet and the return passage.

  In another preferred embodiment, the mixed fuel adhering to the outer peripheral side wall is guided toward the cleaner bottom wall side on the inner periphery of the outer peripheral side wall standing on the outer periphery of the cleaner bottom wall so as to surround the cleaner outlet. Side wall flow guides are provided.

  In a further preferred aspect, a flow path forming rib is provided on the bottom wall of the cleaner, one end of which is connected to the side wall flow guiding portion provided on the outer peripheral side wall and the other end of which is connected to the cleaner outlet.

  Preferably, the side wall flow guiding portion is composed of a stepped portion that swells in a triangular shape from the inner periphery to the inner side of the outer peripheral side wall, and a part of the mixed fuel adhering to the outer peripheral side wall is transferred to the flow path. In order to guide to the forming rib, an upper side step portion formed so as to be perpendicular to the cleaner bottom wall and connected to the flow path forming rib, and another portion of the mixed fuel adhering to the outer peripheral side wall are connected to the cleaner bottom wall. And a lower side step portion provided to be inclined with respect to the cleaner bottom wall.

  The fuel reservoir portion preferably includes a dam-like plate portion erected so as to intersect with the cleaner bottom wall so as to be inclined with respect to each other.

  In the air cleaner according to the present invention, in addition to the fuel reservoir for collecting and storing the mixed fuel blown back from the carburetor, the one end side opening communicates with the fuel reservoir, and the other end side opening communicates with the cleaner outlet. Therefore, the mixed fuel accumulated in the fuel reservoir is efficiently recirculated to the carburetor side through the slit-like return passage due to the surface tension of the return passage and the intake negative pressure.

  Therefore, the amount of mixed fuel adhering to the filter is greatly reduced compared to the conventional example, and as a result, problems and troubles caused by the mixed fuel blown back from the vaporizer can be effectively suppressed or reduced. It is possible to extend the service life and reduce the maintenance frequency.

(A) is a top view which shows the case part of one Embodiment of the air cleaner which concerns on this invention, (B) is a top view which shows the state which attached the blow-back guidance member to the case shown by (A). The perspective view of the case shown by FIG. Sectional drawing which follows the XX arrow line of FIG. 1 (B). Sectional drawing which shows the conventional example of an air cleaner with the rear part of a chain saw, and a part of 2 cycle gasoline engine mounted in it. The top view which shows the case part of the air cleaner of the prior art example shown by FIG. The top view which shows the attachment state of the blow-back guidance member used for the air cleaner of the prior art example shown by FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 (A) is a plan view showing a case portion of an embodiment of an air cleaner according to the present invention, and FIG. 1 (B) shows a state where a blow back guide member is attached to the case shown in FIG. 1 (A). 2 is a perspective view of the case shown in FIG. 1A, and FIG. 3 is a cross-sectional view taken along the line XX in FIG.

  The air cleaner 10 of the present embodiment includes the basic configuration of the conventional air cleaner 10 ′ shown in FIGS. 4 and 5 described above, that is, the case 11, the filter 12, the cover 13, the screw member 18, the blow back guide member 19, and the like. The configuration is the same, and basically the configuration of the case 11 (and the configuration of each part associated therewith) is different. Therefore, the portions corresponding to the respective portions of the air cleaner 10 ′ of the conventional example are denoted by common reference numerals. A duplicate description will be omitted, and the following will focus on the differences.

  The case 11 of the air cleaner 10 of the present embodiment basically has a bottom wall 15 having a substantially rectangular flat plate shape and an outer peripheral side wall 15C standing on the outer periphery of the bottom wall 15. In order to collect and store the mixed fuel blown back from the vicinity of the cleaner outlet 20 provided on the vaporizer side bottom wall (cleaner bottom wall) 15A of the bottom wall 15 (for example, a cleaner outlet in a normal use (working) state) A fuel reservoir 30 is formed at a position lower than 20). Moreover, in this embodiment, the screw attachment part 17A in which the internal thread part 17 into which the screw member 18 for attaching and detaching the cover 13 and the filter 12 is formed is extended at the upper and lower centers of the outer peripheral side wall 15C.

  The fuel reservoir 30 is erected on the bottom wall 15 in an inverted shape mainly so as to partition the carburetor side bottom wall 15A and the carburetor side bottom wall 15A and the cleaner inlet side bottom wall 15B. And two dam-like plate portions 31 and 32. The two weir-shaped plate portions 31 and 32 each have one end connected to the outer peripheral side wall 15C forming the outer peripheral portion of the carburetor-side bottom wall 15A, and the other end sides intersecting with each other so that the mixed fuel is blown back. Is blocked so as not to flow from the vaporizer side bottom wall 15A to the cleaner inlet side bottom wall 15B, and the mixed fuel is collected and collected at the intersection of the dam-like plate portions 31 and 32.

  Further, in the case 11, one end side opening communicates with the fuel reservoir 30 in order to return the mixed fuel stored in the fuel reservoir 30 to the carburetor 65 side using surface tension and intake negative pressure, A slit-like return passage 35 having an opening at the other end communicating with the cleaner outlet 20 is provided.

  The return passage 35 is formed between two plate-like ribs 33, 34 erected in parallel with the vaporizer-side bottom wall 15 </ b> A, and an interval between the plate-like ribs 33, 34 (in other words, For example, the passage width of the return passage 35) is the amount of the mixed fuel stored in the fuel reservoir 30 opened at one end of the return passage 35 in the return passage 35 (gap between the plate-like ribs 33 and 34) due to surface tension and intake negative pressure. It is said that the distance can be sucked up. The plate-like ribs 33 and 34 have a height slightly lower than the height of the dam-like plate portions 31 and 32 so that the mixed fuel blown back is directed to the fuel reservoir 30 side instead of the filter 12 side. The blow-back guiding member 19 for guiding to the right side is positioned at a predetermined distance from the tips of the plate-like ribs 33, 34. That is, in the present embodiment, the blow back guiding member 19 is disposed so as to cover the cleaner outlet 20 and the return passage 35 and at a predetermined distance from the cleaner outlet 20 and the return passage 35 ( (See FIG. 3).

  In the present embodiment, the blow back guiding member 19 is formed in a substantially rectangular shape having a width slightly larger than the diameter of the cleaner outlet 20.

  Further, in the case 11, one end is connected to the outer peripheral side wall 15C in order to return the mixed fuel adhering to the outer peripheral side wall 15C and the carburetor side bottom wall 15A to the carburetor 65 side using the intake negative pressure. Flow path forming ribs 41, 42, 43, 44 whose ends are connected to the cleaner outlet 20 and slightly lower than the plate-like ribs 33, 34 are erected on the vaporizer side bottom wall 15 </ b> A. Each flow path forming rib 41, 42, 43, 44 is formed substantially radially around the cleaner outlet 20, and the height thereof is substantially the same as the height of the boss portion 20 a of the cleaner outlet 20. Further, one end of the flow path forming ribs 41 and 42 is connected to the inner periphery on the left side of the outer peripheral side wall 15C (viewed from the filter 12 side), and one end of the flow path forming ribs 43 and 44 is connected to the inner side on the right side of the outer peripheral side wall 15C. It goes to the lap.

  Further, in this embodiment, the mixed fuel adhering to the dam-like plate portion 32 (the longer dam-like plate portion of the two dam-like plate portions 31 and 32) or the vaporizer side bottom wall 15A is used by using the intake negative pressure. In order to recirculate to the vaporizer 65 side, the flow is substantially the same height as the flow path forming ribs 41, 42, 43, 44, one end of which is connected to the dam-like plate portion 32 and the other end is connected to the cleaner outlet 20. The passage forming rib 45 is also erected on the vaporizer side bottom wall 15A.

  Further, in the case 11, a step swelled in a triangular shape from the inner periphery to the inner periphery of the outer peripheral side wall 15C so as to guide the mixed fuel adhering to the outer peripheral side wall 15C toward the carburetor-side bottom wall 15A. Side wall flow guides 46, 47, 48, 49 are provided.

  The side wall flow guiding portions 46, 47, 48, and 49 respectively transfer part of the mixed fuel adhering to the outer peripheral side wall 15C to the flow path forming ribs 41, 42, 43, and 44 provided on the vaporizer side bottom wall 15A. In order to guide, upper side step portions 46a, 47a, 48a, 49a formed perpendicular to the vaporizer side bottom wall 15A and connected to the flow path forming ribs 41, 42, 43, 44, and the outer peripheral side wall 15C. In order to guide the other part of the mixed fuel adhering to the carburetor-side bottom wall 15A, the lower side step portion 46b formed so as to be inclined with respect to the carburetor-side bottom wall 15A and connected to the carburetor-side bottom wall 15A. , 47b, 48b, 49b. The side wall flow guiding portion 46 is disposed above the side wall flow guiding portion 47 (that is, above one end of the flow path forming rib 42) on the left inner periphery of the outer peripheral side wall 15C. In the inner circumference on the right side of 15C, the side wall flow guiding portion 49 is disposed above (that is, above one end of the flow path forming rib 44).

  Note that the vaporizer-side bottom wall 15A of the present embodiment has rib-like partition plate portions 36 and 37 extending in the lateral direction so as to connect the boss portion 29a of the insertion hole 29 and the outer peripheral side wall 15C, and the boss of the cleaner outlet 20. A rib-like partition plate portion 38 extending in the vertical direction so as to connect the portion 20 a and the dam-like plate portion 32 is also erected, and the side wall flow guide portions 46, 47, 48, 49 are arranged in the rib-like partition plate portion 36. , 37 and the dam-like plate portions 31, 32 are formed above.

  In the air cleaner 10 of the present embodiment having such a configuration, the mixed fuel (gasoline and lubricating oil) once atomized by the carburetor 65 is blown back into the case 11 by blow-back from the intake port 63. It is. This blown-back flow is shown by broken line arrows in FIGS. The blown-back mixed fuel is guided by the blow-back guiding member 19 not toward the filter 12 but toward the fuel reservoir 30 and is stored there. In particular, in a normal use (working) posture, the fuel reservoir 30 is positioned below, so that the mixed fuel blown back is collected and stored in the fuel reservoir 30 by its own weight. The mixed fuel stored in the fuel reservoir 30 is sucked to the cleaner outlet 20 side through the slit-like return passage 35 by intake negative pressure at the time of suction after blow-back. In this case, the mixed fuel stored in the fuel reservoir 30 is easily sucked into the return passage 35 by the surface tension of the slit-like return passage 35 (suctioned upward in a normal use posture), and the cleaner outlet 20 Then, the remaining mixed fuel is sucked one after another into the return passage 35 and returned to the vaporizer 65 via the cleaner outlet 20. The flow after this blow-back is shown by solid line arrows in FIG. 1 (A) and FIG.

  Further, the mixed fuel adhering to the vaporizer side bottom wall 15A out of the mixed fuel blown back is flow path forming ribs 41, 42, 43, 44, 45 and rib-shaped partitions due to intake negative pressure, gravity, etc. The air is sucked to the cleaner outlet 20 side (transmitted) through the plate portions 36, 37, 38 and the like.

  Further, a part of the mixed fuel adhering to the outer peripheral side wall 15C is transferred to the upper side step portions 46a, 47a, 48a, 49a of the side wall flow guiding portions 46, 47, 48, 49 due to intake negative pressure, gravity, etc. In contact with the vaporizer side bottom wall 15A side (that is, the flow path forming ribs 41, 42, 43, 44) and sucked to the cleaner outlet 20 side in the same manner as described above, and other parts (upper side step part 46a, The mixed fuel that has not been led to the carburetor-side bottom wall 15A side by 47a, 48a, 49a) is the lower side of the side wall flow guiding portions 46, 47, 48, 49 due to intake negative pressure, surface tension, etc. It is guided to the vaporizer side bottom wall 15A side through the parts 46b, 47b, 48b, 49b. In this case, the mixed fuel guided to the carburetor-side bottom wall 15A side through the lower side step portions 46b, 48b of the side wall flow guide portions 46, 48 is the upper side step portion of the lower side wall flow guide portions 47, 49. 47a, 49a and the flow path forming ribs 42, 44 connected thereto are easily contacted, and most of them are sucked to the cleaner outlet 20 via the flow path forming ribs 42, 44. Further, the mixed fuel guided to the carburetor-side bottom wall 15A side through the lower side step portions 47b and 49b of the side wall flow guiding portions 47 and 49 is likely to come into contact with the lower rib-like partition plate portions 36 and 37. Most of the air was sucked to the cleaner outlet 20 side via the rib-like partition plate portions 36 and 37 and was not sucked to the cleaner outlet 20 side via the rib-like partition plate portions 36 and 37. The mixed fuel is stored in the fuel reservoir 30 through the lower weir plate portions 31 and 32, and is sucked to the cleaner outlet 20 side through the return passage 35 as described above. The flow after the blow-back is shown by a one-dot chain arrow in FIG.

  Thus, in the air cleaner 10 of the present embodiment, in addition to the fuel reservoir 30 that collects and stores the mixed fuel blown back from the carburetor 65, one end side opening communicates with the fuel reservoir 30 and the other end side Since the slit-like return passage 35 having a predetermined passage width is provided with the opening communicating with the cleaner outlet 20, the mixed fuel accumulated in the fuel reservoir 30 is generated immediately after the surface tension of the return passage 35 and the blowback. Due to the intake negative pressure, the air is efficiently recirculated to the carburetor 65 side through the return passage 35 and the cleaner outlet 20.

  Therefore, the amount of mixed fuel adhering to the filter 12 is greatly reduced as compared with the conventional one, and as a result, problems and troubles caused by the mixed fuel blown back from the carburetor 65 can be suppressed or reduced. It is possible to extend the service life and reduce the maintenance frequency.

  Further, by reducing the amount of fuel adhering to the filter 12, it is possible to improve fuel efficiency and reduce the amount of harmful substances discharged.

  Further, since the return passage 35 is formed between the two plate-like ribs 33 and 34 erected in parallel with the vaporizer-side bottom wall 15A, the return passage 35 is formed with a simple configuration. You can also.

  Further, since the blow back guiding member 19 is disposed so as to cover the cleaner outlet 20 and the return passage 35 and at a predetermined distance from the cleaner outlet 20 and the return passage 35, the blow back guiding member 19 has a reflux effect. In addition, the return passage 35 is still open on the opposite side of the return passage 35 from the vaporizer-side bottom wall 15A. Therefore, even if foreign matter or the like enters the return passage 35, the return passage 35 is not clogged.

  Further, on the inner periphery of the outer peripheral side wall 15C, there are provided side wall flow guiding portions 46, 47, 48, 49 each including a stepped portion bulging inward from the inner periphery of the outer peripheral side wall 15C, and the vaporizer side bottom wall 15A is provided with flow path forming ribs 41, 42, 43, 44 standing at one end and connected to the side wall flow guiding portions 46, 47, 48, 49 and the other end to the cleaner outlet 20. Of the mixed fuel, the mixed fuel adhering to the outer peripheral side wall 15C and the carburetor-side bottom wall 15A is also efficiently returned to the carburetor 65 side via the cleaner outlet 20 due to negative intake pressure, gravity, and the like generated immediately after blowing back. It is done.

  In this embodiment, the fuel reservoir 30 is configured to include two dam-like plate portions 31 and 32. However, the configuration of the fuel reservoir 30 stores the blown-back mixed fuel around the cleaner outlet 20. If possible, the shape is not limited. For example, the vaporizer-side bottom wall 15A and the cleaner inlet-side bottom are prevented from flowing back from the vaporizer-side bottom wall 15A toward the cleaner inlet-side bottom wall 15B. A step may be simply provided between the wall 15B and the wall 15B.

  Further, the blow back guiding member 19 is not limited to that of the above embodiment, and if the mixed fuel blown back into the air cleaner (case 11) can be guided not to the filter 12 side but to the fuel reservoir 30 side, the shape / A material etc. are not limited and you may shape | mold integrally with case 11 made from a synthetic resin.

  In the present embodiment, the return passage 35 is linear and has a constant passage width. However, for example, the return passage 35 may be curved as long as the mixed fuel stored in the fuel reservoir 30 is sucked up. The passage width (that is, the interval between the plate-like ribs 33 and 34) may not be constant.

  Further, the plate-like ribs 33 and 34, the flow path forming ribs 41 to 45, the side wall flow guide portions 46 to 49, etc. constituting the return passage 35 are integrated with the case 11 made of synthetic resin (the bottom wall 15A and the outer side wall 15C). Of course, it may be formed separately, but the material and the like are not limited.

  Furthermore, in the present embodiment, only one fuel reservoir 30 and one return passage 35 are provided, but depending on the usage posture of the power working machine (chain saw, brush cutter, engine cutter, hedge trimmer, etc.) Of course, a plurality of fuel reservoirs and return passages may be provided.

10 Air Cleaner 11 Case 12 Filter 13 Cover 15 Bottom Wall (Cleaner Bottom Wall)
15A carburetor side bottom wall 15B cleaner inlet side bottom wall 15C outer peripheral side wall 19 blow back guiding member 20 cleaner outlet 30 fuel reservoir 31, 32 weir plate 33, 34 plate rib 35 return passages 41, 42, 43, 44, 45 Flow path forming ribs 46, 47, 48, 49 Side wall flow guiding portion

Claims (9)

An air cleaner disposed immediately upstream of a carburetor in an intake system of an engine,
A fuel reservoir portion that is formed around a cleaner outlet provided on a cleaner bottom wall located on the vaporizer side, collects and stores the mixed fuel blown back from the vaporizer, and a mixed fuel that accumulates in the fuel reservoir portion A slit-like return passage in which one end side opening communicates with the fuel reservoir and the other end side opening communicates with the cleaner outlet. An air cleaner characterized by comprising:   2. The air cleaner according to claim 1, wherein the return passage is formed between plate-like ribs erected side by side with the cleaner bottom wall.   The air cleaner according to claim 2, wherein the plate-like rib is integrally formed with the cleaner bottom wall.   The air cleaner according to claim 2 or 3, wherein a plurality of plate-like ribs constituting the return passage are arranged in parallel.   A blow back guide member for guiding the mixed fuel blown back into the air cleaner through the cleaner outlet so as to go to the fuel reservoir side instead of the filter side so as to cover the cleaner outlet and the return passage. The air cleaner according to any one of claims 1 to 4, wherein the air cleaner is disposed at a predetermined distance from an outlet and the return passage.   A side wall flow guiding portion for guiding the mixed fuel adhering to the outer peripheral side wall toward the cleaner bottom wall side is provided on the inner periphery of the outer peripheral side wall standing on the outer periphery of the cleaner bottom wall so as to surround the cleaner outlet. The air cleaner according to claim 1, wherein the air cleaner is provided.   The flow path forming rib with which one end is connected with the said side wall flow guidance | induction part provided in the said outer peripheral side wall, and the other end is connected with the said cleaner exit at the said cleaner bottom wall. Air cleaner as described in 1. The side wall flow guiding portion is composed of a stepped portion swelled in a triangular shape from the inner periphery to the inner periphery of the outer peripheral side wall,
The side wall flow guiding portion is formed to be perpendicular to the cleaner bottom wall and to be connected to the flow path forming rib so as to guide a part of the mixed fuel adhering to the outer peripheral side wall to the flow path forming rib. And an upper side step part and a lower side step part provided to be inclined with respect to the cleaner bottom wall so as to guide the other part of the mixed fuel adhering to the outer peripheral side wall to the cleaner bottom wall. The air cleaner according to claim 7, wherein   The said fuel reservoir part is comprised including the dam-like board part erected so that it might mutually incline and cross | intersect the said cleaner bottom wall, The structure of any one of Claim 1 to 8 characterized by the above-mentioned. Air cleaner as described in 1.

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