JP6803414B2 - air cleaner - Google Patents

Description

The present invention comprises a cleaner container that forms a dirty room that communicates with the outside air and a clean room that communicates with the internal combustion engine to which purified air is supplied, a cleaner element that is arranged in the cleaner container between the dirty room and the clean room, and a cleaner. The present invention relates to an air cleaner provided with an intake duct fixed to a container and communicating a dirty room in a space outside the cleaner container.

Patent Document 1 discloses an intake duct that guides air to a carburetor in a motorcycle. The intake duct has a tubular portion connected to the carburetor, a chamber portion provided on the upstream side of the intake of the tubular portion and having an inner diameter larger than that of the tubular portion, and a tubular portion continuously projecting into the internal space of the chamber portion. It is provided with an extension inner wall portion that forms an extension flow path that communicates with the flow path of the tubular portion. By extending the flow path of the tubular portion, the turbulence of the airflow introduced from the tubular portion is suppressed, and the rectification of the airflow is realized.

Japanese Unexamined Patent Publication No. 2011-43165

However, in Patent Document 1, an extra space is required to extend the intake passage, and the structure becomes complicated. Therefore, a technique for effectively realizing rectification in a small space is required.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an air cleaner that effectively realizes rectification in a small space.

According to the first aspect of the present invention, there is a cleaner container that forms a dirty room that communicates with the outside air and a clean room that communicates with the internal combustion engine to which the purified air is supplied, and inside the cleaner container between the dirty room and the clean room. In an air cleaner provided with a cleaner element arranged in the air cleaner element and an intake duct fixed to the cleaner container and communicating the dirty room with the space outside the cleaner container, a first thickness is provided at the upstream end of the intake duct. The wall thickness of the first wall body surrounding the intake passage and the wall thickness of the second wall body larger than the first thickness are maintained, and the distance between the outer wall surface of the first wall body is maintained. a second wall extending in a circumferential direction Te are formed, they first, the space between the second wall body, you open to the upstream end of the intake duct.

According to the second side surface, in addition to the configuration of the first side surface, the second wall body includes a double pipe wall that maintains a distance from the first wall body and the double pipe wall in the circumferential direction. It has a coupling body which is continuously bonded to the first wall body and has an outer surface having a curvature smaller than the outer surface of the double pipe wall.

According to the third aspect, in addition to the configuration of the second aspect, the conjugate of the second wall is solidly formed.

According to the fourth aspect, in addition to the configuration of the second or third aspect, the outer surface of the conjugate forms a gap with the cleaner container.

According to the fifth side surface, in addition to the configuration of any one of the first to fourth side surfaces, at the downstream end of the intake duct, a third wall body surrounding the intake passage and an outer wall surface of the third wall body are provided. A fourth wall body extending in the circumferential direction is formed between the two walls while maintaining a space between them.

According to the sixth side surface, in addition to the configuration of the fifth side surface, the fourth wall body includes a double pipe wall that maintains a distance from the third wall body and the double pipe wall in the circumferential direction. The outer surface of the combined body of the fourth wall body is the cleaner container, and the outer surface of the combined body of the fourth wall body is continuously connected to the third wall body and has an outer surface having a curvature smaller than the outer surface of the double pipe wall. A gap is formed between the and.

According to the seventh aspect, in addition to the configuration of the sixth aspect, the conjugate of the fourth wall is solidly formed.

According to the first side surface, the upstream end of the intake duct is double-piped by the first wall body and the second wall body, and the space between the first and second walls opens to the upstream end side of the intake duct. you. As a result, at the upstream end of the intake duct, the flow velocity in the intake duct is made uniform, and the intake efficiency is improved. There is no need to extend the intake duct, and the airflow in the intake duct can be effectively rectified in a small space. In particular, since the wall thickness of the first wall body is smaller than the wall thickness of the second wall body, the intake efficiency is higher than that when the wall thickness of the first wall body is equal to the wall thickness of the second wall body. Improvements can be promoted.

According to the second aspect, at the upstream end of the intake duct, the flow velocity in the intake duct is further made uniform, and the intake efficiency is improved.

According to the third aspect, the combined body of the second wall body can effectively contribute to the improvement of the intake efficiency.

According to the fourth aspect, when a gap is formed between the outer surface of the coupling and the cleaner container at the upstream end of the intake duct, the outer surface of the coupling is overlapped with the inner surface of the cleaner container without a gap as compared with the case where the gap is formed. , The flow velocity in the intake duct is made uniform, and the intake efficiency is improved.

According to the fifth side surface, since the wall body is arranged at the downstream end of the intake duct, when the negative pressure pressure wave propagates from the downstream end to the upstream end of the intake duct, the negative pressure pressure wave is generated. It swirls along the inner circumference of the downstream end and flows smoothly into the downstream end without backflow. The pressure wave efficiently propagates toward the upstream end. The pressure wave is phase-inverted at the upstream end of the intake duct, and the positive pressure wave propagates from the upstream end to the downstream end. When the pressure wave flows into the dirty room from the downstream end, the pressure wave smoothly flows into the dirty room without being affected by the wall body. In this way, the intake efficiency can be increased. Driving performance is improved.

According to the sixth aspect, when a gap is formed between the outer surface of the coupling and the cleaner container at the downstream end of the intake duct, the outer surface of the coupling is overlapped with the inner surface of the cleaner container without any gap as compared with the case where the gap is formed. , The pressure wave efficiently propagates toward the upstream end. Inspiratory efficiency can be increased.

According to the seventh aspect, the combined body of the fourth wall body can effectively contribute to the improvement of the intake efficiency.

It is a side view which shows roughly the whole image of the saddle-riding vehicle (motorcycle) which concerns on one Embodiment of this invention. It is an enlarged plan view of an air cleaner. It is an enlarged sectional view of the air cleaner observed in a horizontal cut surface. It is an enlarged perspective view which shows roughly the upstream end of the intake duct. (A) A cross-sectional view of an intake duct including a central axis, (B) a plan view from arrow view 5B, and (C) a plan view from arrow view 5C.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In the following description, the front-rear, up-down, and left-right directions refer to the directions seen by the occupants on the motorcycle.

FIG. 1 schematically shows a scooter-type motorcycle according to an embodiment of a saddle-riding vehicle. The motorcycle 11 includes a vehicle body frame 12 and a vehicle body cover 13 mounted on the vehicle body frame 12. A front fork 16 and a rod-shaped steering handle 15 are operably supported on the head pipe of the vehicle body frame 12. The front wheel WF is rotatably supported on the front fork 16 around the axle 14.

The occupant seat 17 is mounted on the vehicle body cover 13 above the rear frame. The vehicle body cover 13 includes a front cover 21 that covers the head pipe from the front, a leg shield 22 that is continuous from the front cover 21, and a leg shield 22 that is continuous from the lower end of the leg shield 22 and is above the main frame between the occupant seat 17 and the front wheel WF. A step floor 23 arranged in the rear frame and a rear cover 24 for supporting the occupant seat 17 on the rear frame are provided. The leg shield 22 is arranged in front of the occupant's knees straddling the occupant's seat 17.

A unit swing type drive unit 25 is arranged below the rear cover 24. The drive unit 25 is swingably connected to the bracket 26 in the vertical direction. The bracket 26 is coupled to the front end of the rear frame. The rear wheel WR is rotatably supported around the horizontal axis at the rear end of the drive unit 25. The rear cushion unit 28 is arranged between the rear frame and the drive unit 25 at a position away from the bracket 26. The rear cushion unit 28 absorbs vibration transmitted to the vehicle body frame 12 from the unevenness of the road surface.

The drive unit 25 includes a water-cooled 4-stroke single-cylinder internal combustion engine 29 and a transmission case 31 that is coupled to the engine body 29a of the internal combustion engine 29 and extends rearward on the left side of the rear wheel WR. The transmission case 31 accommodates a transmission device that transmits the output of the internal combustion engine 29 to the rear wheel WR. The engine body 29a of the internal combustion engine 29 includes a crankcase 33 that rotatably supports a crankshaft around a rotation axis, a cylinder block 34 that is coupled to the crankcase 33, and a cylinder head 35 that is coupled to the cylinder block 34. It includes a head cover 36 coupled to the cylinder head 35. A cylinder is formed in the cylinder block 34 to guide the linear reciprocating motion of the piston. A combustion chamber is formed between the piston and the cylinder head 35. The intake stroke, compression stroke, combustion stroke, and exhaust stroke of the internal combustion engine 29 are repeated according to the linear reciprocating motion of the piston.

The cylinder head 35 is connected to an intake device 37 that is connected to an intake path leading to a combustion chamber and introduces outside air into the intake path, and is connected to an exhaust path leading to the combustion chamber to discharge exhaust gas from the exhaust path toward the outside air environment. It is coupled with the exhaust device 38. The intake device 37 includes an air cleaner 39 that is supported by the transmission case 31 and sucks outside air from the intake port 39a, and a throttle body 41 that connects the air cleaner 39 to the cylinder head 35. A throttle is incorporated in the throttle body 41. The throttle adjusts the flow rate of purified air supplied from the air cleaner 39.

A fuel injection valve 42 is attached to the upper side wall of the cylinder head 35. Fuel is injected into the purified air from the fuel injection valve 42 to form an air-fuel mixture. The air-fuel mixture is introduced into the combustion chamber through the action of the intake valve.

The exhaust device 38 includes an exhaust pipe 43 extending rearward from the lower side wall of the cylinder head 35 through below the engine body 29a, and a silencer connected to the downstream end of the exhaust pipe 43 and connected to the crankcase 33 (not shown). ) And. The exhaust gas after combustion is discharged from the combustion chamber through the action of the exhaust valve.

As shown in FIG. 2, the air cleaner 39 includes a cleaner container 45 that forms an inner space leading to a supply destination (internal combustion engine 29) of outside air and purified air. The cleaner container 45 is divided into an inner space by a first body 45a and a second body 45b that is airtightly coupled to the first body 45a along the vertical surface VP. The vertical plane VP is defined parallel to a virtual plane orthogonal to the rotation axis of the crankshaft. The first body 45a and the second body 45b are molded from, for example, a resin material.

A connecting tube 46 is fixed to the second body 45b. The connecting tube 46 is inserted into the outer wall of the second body 45b and is connected to the throttle body 41 at the downstream end 46a on the outside of the cleaner container 45. The connecting tube 46 is formed of an elastic body such as a rubber material. The connecting tube 46 supplies purified air from the cleaner container 45 to the throttle body 41.

As shown in FIG. 3, a partition wall 48 for holding the cleaner element 47 is sandwiched between the first body 45a and the second body 45b. A dirty room 51a for accommodating unpurified outside air is formed between the partition wall 48 and the first body 45a. A clean room 51b for accommodating purified air is formed between the partition wall 48 and the second body 45b. The inner space of the cleaner container 45 is partitioned into a dirty room 51a and a clean room 51b. The cleaner element 47 is arranged between the dirty room 51a and the clean room 51b. The outside air is purified by the cleaner element 47 and introduced into the clean room 51b.

An indoor duct 52 arranged in the clean room 51b is connected to the upstream end of the connecting tube 46. The indoor duct 52 has tabs 54 that individually overlap with the tips of a plurality of bosses 53 that stand upright from the inner wall of the clean room 51b. The indoor duct 52 is supported in the clean room 51b in a floating state by screwing the tab 54 to the tip of the boss 53. The indoor duct 52 is molded from, for example, a hard resin material.

The upstream end of the indoor duct 52 opens into the clean room 51b. The purified air in the clean room 51b flows into the throttle body 41 from the indoor duct 52 and the connecting tube 46. In this way, the clean room 51b leads to the internal combustion engine 29.

A case cover 56 that covers the first body 45a from the side outside the inner space is connected to the first body 45a. The case cover 56 partitions the introduction chamber 57 from the first body 45a. The introduction chamber 57 is connected to the intake port 39a. Outside air flows into the introduction chamber 57 from the intake port 39a.

An intake duct 58 having an upstream end 58a opened in the introduction chamber 57 and a downstream end 58b opened in the dirty room 51a is fixed to the first body 45a. The inner wall surface 59 of the intake duct 58 partitions an intake passage extending in the front-rear direction of the vehicle in parallel with the partition wall 48 from the upstream end 58a to the downstream end 58b. The inner wall surface 59 has a curved surface area 59a that surrounds a cylindrical space that is long in the axial direction, a diameter expansion area 59b that surrounds a diameter expansion space that expands from the upstream end of the columnar space toward the upstream end of the intake path, and a downstream end of the columnar space. It has an enlarged diameter area 59c surrounding an enlarged diameter space that expands from the to the downstream end of the intake passage. The individual enlarged diameter regions 59b and 59c have an axial length smaller than the wall thickness of the pipe wall that divides the cylindrical space. The unpurified outside air flows into the intake passage from the introduction chamber 57 and is supplied to the dirty room 51a. In this way, the dirty room 51a is open to the outside air.

An attachment port 61 for holding the intake duct 58 is formed on the outer wall of the first body 45a. The intake duct 58 penetrates the outer wall of the first body 45a at the attachment port 61. A pair of fixing flanges 62 that sandwich the outer wall of the first body 45a from the axial direction are formed on the outer wall surface of the intake duct 58. The intake duct 58 is axially fixed to the attachment port 61 of the first body 45a by the action of the fixing flange 62. The intake duct 58 is formed of an elastic body such as a rubber material.

As shown in FIG. 4, at the upstream end 58a of the intake duct 58, there is an interval between the first wall body (tube wall) 64 surrounding the intake passage and the outer wall surface of the first wall body 64 at least partially. maintains the Ga and second wall 65 extending in the circumferential direction is formed, which first space between the second wall 64, 65, you open the upstream end 58a side of the intake duct 58. As shown in FIG. 5, the first wall body 64 has a wall thickness of the first thickness t in the radial direction of the circular cross section in the region surrounding the cylindrical space. The wall thickness of the first wall body 64 may be uniform in the circumferential direction. Therefore, the outer wall surface of the first wall body 64 is formed on a curved surface (partial cylindrical surface) coaxial with the central axis Xc of the cylindrical space.

The second wall body 65 is connected to the double pipe wall 65a that maintains a gap Ga between the first wall body 64 and the first wall body 64 continuously from the double pipe wall 65a in the circumferential direction, and is double. It has a coupling 65b having an outer surface having a curvature smaller than the outer surface of the tube wall 65a. The conjugate 65b is solidly formed. Here, two conjugates 65b are arranged in the circumferential direction. The outer surface of the conjugate 65b is formed in a plane. As shown in FIG. 3, the outer surface of the coupling 65b faces the outer wall surface of the cleaner container 45 and the inner wall surface of the case cover 56, respectively. A gap Ca is partitioned between the outer surface of the conjugate 65b and the outer wall surface of the cleaner container 45. A gap Cb is partitioned between the outer surface of the coupling 65b and the inner wall surface of the case cover 56.

As shown in FIG. 5, the double pipe wall 65b of the second wall body 65 has a wall thickness of a second thickness s larger than the first thickness t in the radial direction of the circular cross section. The wall thickness of the double pipe wall 65b may be uniform in the circumferential direction. Therefore, the inner wall surface and the outer wall surface of the double pipe wall 65b are formed on a curved surface (partial cylindrical surface) coaxial with the central axis Xc of the cylindrical space.

A flange body 66 that extends outward from the outer wall surface and is connected to the downstream end of the double pipe wall 65b is connected to the downstream end of the first wall body 64. The flange body 66 closes the downstream end of the gap Ga. The first thickness t of the first wall body 64 is set to be thinner than the pipe wall downstream from the flange body 66. Therefore, the gap Ga is closer to the intake passage than when it surrounds the pipe wall.

Here, the upstream end of the second wall 65 is in contact with the virtual plane PL including the upstream end of the first wall 64. That is, the upstream end of the first wall body 64 and the upstream end of the second wall body 65 are on the same virtual plane. However, the upstream end of the second wall body 65 may extend forward of the virtual plane PL including the upstream end of the first wall body 64 and intersect the virtual plane PL.

The distance DF between the outer wall surface of the first wall body 64 and the double pipe wall 65b is set to 10% to 30% of the outer diameter DP of the cylindrical space. Here, since the first wall body 64 and the second wall body 65 are formed in a coaxial cylindrical body, the distance DF corresponds to the radial difference between the outer wall surface of the first wall body 64 and the second wall body 65. To do.

At the downstream end 58b of the intake duct 58, a distance Gb is maintained between the third wall (tube wall) 67 surrounding the intake passage and the outer wall surface of the third wall 67 in the circumferential direction. An extending fourth wall body 68 is formed. The third wall body 67 has a wall thickness of a third thickness y in the radial direction of the circular cross section in a region surrounding the cylindrical space. The wall thickness of the third wall body 67 may be uniform in the circumferential direction. Therefore, the outer wall surface of the third wall body 67 is formed on a curved surface (partial cylindrical surface) coaxial with the central axis Xc of the cylindrical space.

The fourth wall body 68 is connected to the double pipe wall 68a that maintains an interval Gb between the third wall body 67 and the third wall body 67 continuously from the double pipe wall 68a in the circumferential direction, and is double. It has a coupling 68b having an outer surface having a curvature smaller than the outer surface of the tube wall 68a. The conjugate 68b is solidly formed. Here, two conjugates 68b are arranged in the circumferential direction. The outer surface of the conjugate 68b is formed in a plane. The outer surface of the conjugate 68b faces the inner wall surface of the cleaner container 45. A gap Cd is partitioned between the outer surface of the combined body 68b and the inner wall surface of the cleaner container 45.

The double pipe wall 68a of the fourth wall body 68 has a wall thickness of a fourth thickness q equal to the third thickness y in the radial direction of the circular cross section. The wall thickness of the fourth wall body q may be uniform in the circumferential direction. Therefore, the inner wall surface and the outer wall surface of the double pipe wall 68a are formed on a curved surface (partial cylindrical surface) coaxial with the central axis Xc of the cylindrical space.

A flange body 69 that extends outward from the outer wall surface and is connected to the upstream end of the double pipe wall 68a is connected to the upstream end of the third wall body 67. The flange body 69 closes the upstream end of the gap Gb. The third thickness y of the third wall body 67 is set to a thickness equal to the pipe wall upstream from the flange body 69. Therefore, the third thickness y of the third wall body 67 is larger than the first thickness t of the first wall body 65.

Here, the downstream end of the fourth wall 68 is in contact with the virtual plane PM including the downstream end of the third wall 67. That is, the downstream end of the third wall 67 and the downstream end of the fourth wall 68 are on the same virtual plane. However, the downstream end of the fourth wall body 68 may extend rearward from the virtual plane PM including the downstream end of the third wall body 67 and intersect the virtual plane PM.

The distance DG between the outer wall surface of the third wall body 67 and the double pipe wall 68a is set to 10% to 30% of the outer diameter DP of the cylindrical space. Here, since the third wall body 67 and the fourth wall body 68 are formed in a coaxial cylindrical body, the distance DG corresponds to the radial difference between the outer wall surface of the third wall body 67 and the fourth wall body 68. To do.

Next, the operation of this embodiment will be described. When the intake stroke, compression stroke, combustion stroke, and exhaust stroke of the internal combustion engine 29 are repeated according to the linear reciprocating motion of the piston, the outside air is introduced from the intake duct 58 into the dirty room 51a in the cleaner container 45. The outside air passes through the cleaner element 47, is purified, and is introduced into the clean room 51b. The purified air in the clean room 51b flows into the connecting tube 46 from the indoor duct 52 and is supplied to the throttle body 41. In the throttle body 41, the flow rate of purified air supplied from the air cleaner 39 is adjusted by the action of the throttle. Fuel is injected from the fuel injection valve 42 into the purified air flowing out of the throttle body 41 to form an air-fuel mixture. The air-fuel mixture is introduced into the combustion chamber through the action of the intake valve.

In the present embodiment, the upstream end 58a of the intake duct 58 is double-piped by the first wall body 64 and the second wall body 65, and the space between the first and second wall bodies 64 and 65 is the intake duct 58. you open to the upstream end 58a side. As a result, at the upstream end 58a of the intake duct 58, the flow velocity in the intake duct 58 is made uniform, and the intake efficiency is improved. It is not necessary to extend the intake duct 58, and the airflow in the intake duct 58 can be effectively rectified in a small space. In particular, since the wall thickness of the first wall body 64 is smaller than the wall thickness of the second wall body 65, compared with the case where the wall thickness of the first wall body 64 is equal to the wall thickness of the second wall body 65. , Improvement of inspiratory efficiency can be promoted.

In the intake duct 58 according to the present embodiment, the double pipe wall 65a that maintains a gap Ga between the first wall body 64 and the double pipe wall 65a is continuously connected to the first wall body 64 in the circumferential direction. The second wall 65 is formed by the coupling 65b having an outer surface having a curvature smaller than that of the double pipe wall 65a. As a result, at the upstream end of the intake duct 58, the flow velocity in the intake duct is made uniform as compared with the case where the gap is reduced in accordance with the reduction of the curvature when the curvature of the outer surface of the second wall body 65 is reduced. , The intake efficiency is improved. The present inventor confirmed this effect based on the analysis.

At the upstream end 58a of the intake duct 58, the outer surface of the coupling 65a forms gaps Ca and Cb between the cleaner container 45 and the case cover 56. When gaps Ca and Cb are formed between the outer surface of the coupling 65a and the cleaner container 45 and the case cover 56 at the upstream end 58a of the intake duct 58, the outer surface of the coupling 65a becomes the cleaner container 45 and the case cover 56. Compared with the case where they are stacked without a gap, the flow velocity in the intake duct 58 is made uniform, and the intake efficiency is improved. The present inventor confirmed this effect based on the analysis.

The pulsating effect is utilized in the intake of the internal combustion engine 29. When the intake valve is opened, a negative pressure wave is generated and propagates at a sonic velocity from the downstream end 58b of the intake duct 58 to the upstream end 58a of the intake duct 58 via the clean room 51b and the dirty room 51a. The pressure wave reverses at the upstream end 58a of the intake duct 58, becomes positive pressure, rebounds, and returns to the dirty room 51a and the clean room 51b from the downstream end 58b of the intake duct 58.

At this time, in the present embodiment, since the downstream end 58b of the intake duct 58 is double-piped by the third wall 67 and the fourth wall 68, the negative pressure pressure wave is generated by the downstream end 58b of the intake duct 58. When propagating from the upstream end 58a toward the upstream end 58a, the negative pressure pressure wave smoothly flows into the downstream end 58b without swirling backflow along the inner circumference of the downstream end 58b. The pressure wave efficiently propagates toward the upstream end 58a. The pressure wave is phase-inverted at the upstream end 58a of the intake duct 58, and the positive pressure wave propagates from the upstream end 58a to the downstream end 58b. When the pressure wave flows into the dirty room 51a from the downstream end 58b, the pressure wave smoothly flows into the dirty room 51a without being affected by the fourth wall body 68. In this way, the intake efficiency is increased. Driving performance is improved.

Here, the fourth wall body 68 is continuously joined to the third wall body 67 from the double pipe wall 68a in the circumferential direction with the double pipe wall 68a that maintains the distance Gb between the fourth wall body 68 and the third wall body 67. , With a coupling 68b having an outer surface with a curvature smaller than the outer surface of the double tube wall 68a. The outer surface of the combined body 68b of the fourth wall body 68 forms a gap Cd with the cleaner container 45. As a result, the pressure wave propagates efficiently toward the upstream end 58a as compared with the case where the outer surface of the coupling body 68b is superposed on the inner surface of the cleaner container 45 without a gap. Inspiratory efficiency is increased.

In the above embodiment, a scooter type motorcycle has been described as an example of a saddle-riding vehicle, but the present invention is not limited to this, and the present invention includes a motorcycle, two front wheels or two rear wheels. It can be applied to a three-wheeled saddle-riding vehicle and a saddle-riding vehicle equipped with four or more wheels.

Further, in the above embodiment, the water-cooled 4-stroke internal combustion engine has been described as an example of the internal combustion engine, but the present invention is not limited to this, and the present invention is an air-cooled, 2-stroke, or multi-cylinder internal combustion engine. Applicable to institutions.

29 ... Internal engine, 39 ... Air cleaner, 45 ... Cleaner container, 47 ... Cleaner element, 51a ... Dirty room, 51b ... Clean room, 58 ... Intake duct, 58a ... Upstream end, 58b ... Downstream end, 64 ... First wall , 65 ... 2nd wall, 65a ... Double tube wall, 65b ... Combine, 67 ... 3rd wall, 68 ... 4th wall, 68a ... Double tube wall, 68b ... Combine, Ca ... Gap (between the outer surface of the body and the container), Cd ... (gap between the outer surface of the bond and the container), Ga ... (of the first and second walls), Gb ... (third wall and fourth) Interval (of the wall body), t ... 1st thickness, s ... 2nd thickness.

Claims (7)

A cleaner container (45) forming a dirty room (51a) that communicates with the outside air and a clean room (51b) that communicates with the internal combustion engine (29) to which the purified air is supplied.
A cleaner element (47) arranged in the cleaner container (45) between the dirty room (51a) and the clean room (51b).
In an air cleaner (39) provided with an intake duct (58) fixed to the cleaner container (45) and communicating the dirty room (51a) with a space outside the cleaner container (45).
The upstream end (58a) of the intake duct (58) has a wall thickness of the first thickness (t), and is larger than the first wall body (64) surrounding the intake passage and the first thickness (t). A second wall body (65) having a large wall thickness of a second thickness (s) and extending in the circumferential direction while maintaining a distance (Ga) from the outer wall surface of the first wall body (64) is formed, which first, the space between the second wall (64, 65), said upstream end (58a) the air cleaner and said opening to Rukoto the side over the intake duct (58). In the air cleaner according to claim 1, the second wall body (65) has a double pipe wall (65a) that maintains a distance (Ga) from the first wall body (64) and a circumferential direction. Has a coupling (65b) which is continuous from the double pipe wall (65a) and is coupled to the first wall body (64) and has an outer surface having a curvature smaller than the outer surface of the double pipe wall (65a). An air cleaner that features that. The air cleaner according to claim 2, wherein the combined body ( 65 b) of the second wall body ( 65 ) is solidly formed. The air cleaner according to claim 2 or 3, wherein the outer surface of the combined body (65b) forms a gap (Ca) with the cleaner container (45). In the air cleaner according to any one of claims 1 to 4, at the downstream end (58b) of the intake duct (58), a third wall body (67) surrounding the intake passage and the third wall body An air cleaner characterized in that a fourth wall body (68) extending in the circumferential direction is formed with the outer wall surface of (67) while maintaining a distance (Gb). In the air cleaner according to claim 5, the fourth wall body (68) has a double pipe wall (68a) that maintains a distance (Gb) from the third wall body (67) and a circumferential direction. There is a combined body (68b) which is continuously connected to the third wall body (67) from the double pipe wall (68a) and has an outer surface having a curvature smaller than the outer surface of the double pipe wall (68a). An air cleaner characterized in that the outer surface of the combined body (68b) of the fourth wall body (68) forms a gap (Cd) with the cleaner container (45). The air cleaner according to claim 6, wherein the combined body (68b) of the fourth wall body (68) is solidly formed.