Structure of air cleaner of motorcycle

A compact air cleaner for a motorcycle engine has its intake duct directed in a widthwise direction of the motorcycle. The air cleaner includes an air cleaner case, an air cleaner element and a case cover. The air cleaner element partitions an inner portion of the air cleaner case and case cover into a clean room and a dirty room. The air cleaner element extends in the motorcycle's travel direction. An intake port communicates with the dirty room and opens to a space surrounded by a rear face of the clean room, a front portion of a rear fender and a bottom portion of a seat.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to a structure of an air cleaner of a
 motorcycle.
 2. Description of the Background Art
 Air cleaners for motorcycle engines are well known. One air cleaner
 structure for a motorcycle is shown in Japanese Utility Model Registration
 No. 2537385. In the shown air cleaner, a clean room and a dirty room are
 arranged in a widthwise direction of a vehicle with a flat plate air
 cleaner element disposed therebetween. Air is sucked from a rearward
 direction of a motorcycle via a rearwardly extending intake duct. The air
 passes into the dirty room, through the air cleaner element, into the
 clean room, then to the engine.
 When an air cleaner is constructed, as in the above-described conventional
 example, a capacity/size of the dirty room and a length/size of the intake
 duct all add to the size of the air cleaner in the lengthwise direction of
 the motorcycle. In order to have an air cleaner which functions
 sufficiently, a side face of the air cleaner, including the dirty room and
 the intake duct, is extended in length, thereby making the air cleaner
 bulky in construction.
 SUMMARY OF THE INVENTION
 It is an object of the present invention to provide an air cleaner of
 compact construction. Particularly, it is an object of the present
 invention to provide an air cleaner which has a compact construction in a
 lengthwise direction of the motorcycle.
 It is a further object of the present invention to provide an air cleaner
 with improved ventilation efficiency.
 It is an even further object of the present invention to provide an air
 cleaner having an intake duct which is less susceptible to invading water
 or dust.
 These and other objects of the present invention are achieved by providing
 an air cleaner for an engine of a vehicle, said air cleaner comprising: an
 air intake port extending in a first direction to accept outside air; an
 air flow path connected to said air intake port for redirecting a flow of
 the outside air approximately 180 degrees and yielding redirected air into
 a dirty air chamber; an air cleaner element adjoining said dirty air
 chamber for filtering the redirected air and for producing cleaned air;
 and a clean air chamber adjoining said air cleaner element for accepting
 the cleaned air and for directing the cleaned air toward the engine.
 These and other objects of the present invention are achieved by providing
 a motorcycle comprising: a frame; an engine attached to said frame; a seat
 attached to said frame; a rear wheel fender attached to said frame; an air
 intake port extending in a first direction to accept outside air at a
 first location; an air flow path connected to said air intake port for
 redirecting a flow of the outside air approximately 180 degrees and
 yielding redirected air into a dirty air chamber; an air cleaner element
 adjoining said dirty air chamber for filtering the redirected air and for
 producing cleaned air; a clean air chamber adjoining said air cleaner
 element for accepting the cleaned air; and an outlet port connected to
 said clean air chamber for passing the cleaned air toward said engine.
 Further scope of applicability of the present invention will become
 apparent from the detailed description given hereinafter. However, it
 should be understood that the detailed description and specific examples,
 while indicating preferred embodiments of the invention, are given by way
 of illustration only, since various changes and modifications within the
 spirit and scope of the invention will become apparent to those skilled in
 the art from this detailed description.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
 With reference to FIG. 2, structures of a motorcycle, including an air
 cleaner 10 in accordance with the present invention, will be described. A
 front end 1 of the motorcycle includes a front fork 2 and handlebars 5. An
 upper portion of the front fork 2 is attached to a head pipe 3. The head
 pipe 3 is attached to a vehicle body frame 5.
 The vehicle body frame 5 supports a fuel tank 6 and a seat 7 on an upper
 side. The vehicle body frame 5 supports an engine 8 on a lower side. The
 engine 8 is a water-cooled type, cooled by a radiator 9. The engine 8
 intakes air from the air cleaner 10 on the lower side of the seat 7. The
 engine accepts the air via a carburetor 11 and exhausts gas from an
 exhaust port via an exhaust pipe 12.
 A rear swing arm 14 is supported by a pivot portion 15 attached to a
 portion of the vehicle body frame 5 on the rear side of a crank case 13 of
 the engine 8. The swing arm can swing in the up and down direction. A rear
 shock absorber 16 is installed between the rear swing arm 14 and the
 vehicle body frame 5.
 A rear wheel 17 is supported by a rear end portion of the rear swing arm
 14. The rear wheel 17 is driven by a side sprocket 18 connected to a chain
 19 connected to a drive side sprocket 20 of the crank case 13. The rear
 wheel 17 can move up and down by swinging the rear swing arm 14.
 A rear portion of the air cleaner 10 is arranged adjacent the rear wheel
 17. The air cleaner 10 is arranged such that when the rear wheel 17 is
 moved to an uppermost position (as shown by the dotted line in FIG. 2),
 the air cleaner 10 does not contact or interfere with the rear wheel 17,
 but overlaps a side thereof. Thereby, even when the rear wheel 17 is
 arranged to be proximate to the engine 8, a capacity of the air cleaner 10
 can be sufficiently large.
 Further, as discussed hereinafter, an air cleaner element 41 in conformity
 with a shape of a side face of the air cleaner 10 is provided inside the
 air cleaner 10. By having the air cleaner element 41 in conformity with
 the shape of the side face, the air cleaner element can have a large
 surface area.
 The motorcycle also includes a step bracket 21, a chain protector 22, a
 rear stay 23, a seat rail 24 and a rear fender 25. The vehicle body frame
 5 is formed in a loop shape in side view.
 The vehicle body frame 5 includes a head pipe 30, a main pipe 31, a center
 pipe, a pivot frame 33, lower pipes 34, a down pipe 35 and a reinforcement
 pipe 36. Of these pipes and frames, single ones of the main pipe 31, the
 center pipe, the pivot frame 33 and the down pipe 35 are arranged along
 the center of the vehicle body to thereby constitute a backbone type
 frame. Further, left and right pairs of the lower pipes 34, the rear stays
 23 and the seat rails 24 are respectively installed.
 The head pipe 30 is a hollow member integrated with the head pipe 3 and
 cast by using a pertinent metal material of an aluminum alloy or the like.
 The main pipe 31 is a member constituting a straight shape in a square
 pipe shape constructed of a suitable metal material. A front end portion
 of the main pipe 31 is coupled to the head pipe 30 by welding, a rear end
 portion thereof is cut obliquely and is brought into contact with and
 welded to an upper end portion of the center pipe which is similarly cut
 obliquely.
 The center pipe is a square pipe member constituting a straight shape
 constructed of a suitable metal material of an aluminum alloy or the like.
 The center pipe is provided with a section similar to that of the main
 pipe 31. A rear face side of the center pipe, at a vicinity of a joint
 portion, joins with the main pipe 31, and is welded with a bracket having
 portions for attachment to the seat rails 24 and the rear shock absorber
 16. A lower end portion of the center pipe is brought into contact with
 and welded to an upper end portion of the pivot frame 33.
 The pivot frame 33 is fabricated by casting an aluminum alloy and
 constitutes a substantially U-shaped configuration, opening to the front
 side of the motorcycle. An intermediary portion of the pivot frame 33 is
 provided with a pivot portion 15. A lower end portion of the pivot frame
 33 is provided with lower pipe joint portions 38 to which rear end
 portions of the lower pipes 34 are fitted and welded.
 The lower pipes 34 are arranged in the forward and rearward direction on
 the lower side of the engine 8. Front end portions of the lower pipes 34
 are bent upwardly and welded to a lower end portion of the down pipe 35
 via a joint piece (illustration is omitted). The joint piece is a casting
 of an aluminum alloy or the like.
 Next, an explanation will be given of a detailed structure of the air
 cleaner, in accordance with the present invention. As shown in FIG. 3, the
 air cleaner 10 includes an air cleaner case 40 which is opened to one side
 (e.g. left side) of the vehicle body. A case cover 42 is provided to close
 the one side of the air cleaner case 40.
 The air cleaner case 40 and case cover 42 define an inner space. An air
 cleaner element 41 partitions the inner space formed by the air cleaner
 case 40 and a case cover 42. As shown in FIG. 5, the inside of the air
 cleaner case 40 is partitioned into a clean air chamber, or clean room 43,
 and a dirty air chamber, or dirty room 44, in the vehicle width direction,
 by the air cleaner element 41. As illustrated in FIGS. 1 and 3, the air
 cleaner element 41 is a generally planar member which extends
 approximately vertically and in the forward and rearward direction, or
 travel direction of the vehicle.
 As illustrated in FIG. 3, the clean room 43 extends to the other side of
 the vehicle body by passing over the center of the vehicle body (e.g. left
 side to right side of vehicle body). The clean room 43 passes over the
 vehicle body in front of the rear fender 25. A front portion of the clean
 room 43 is connected with a connecting tube 45 to supply clean air to the
 carburetor 11 of the engine 8.
 The dirty room 44 extends rearward along a side face of the rear fender 25.
 The air cleaner case 40 and the case cover 42 are respectively provided
 with rearward extended portions 46a and 46b. The case cover 42 is
 integrally formed with a rear cover portion 47 extending rearward longer
 than the rearward extended portion 46b. The rear cover portion 47 covers
 an opening portion of the air cleaner case 40.
 As shown in FIGS. 1, 3, 6 and 7, an intake port 50 is formed at the
 shoulder portion of the rearward extended portion 46b. The intake port 50
 communicates a space 51 with the dirty room 44. The space 51 is defined by
 a rear face of the clean room 43, a front portion of the rear fender 25,
 and a bottom portion of the seat 7. A notched portion 52 is formed in the
 air cleaning element 41 to correspond with the intake port 50 (see FIG. 3)
 to thereby open the intake port 50 to the dirty room 44.
 As shown in FIG. 4, the case cover 42 is removably attached to the side of
 the air cleaner 40 by coupling pieces 48 of the one touch system type.
 Some of the coupling pieces may also serve as hinges 49. Further, as shown
 in FIG. 6, a portion of the intake port 50 is coupled to a bridge portion
 53 formed at an intermediary portion thereof by the coupling piece 48. A
 portion of the intake port 50 is closed by a cap 54.
 As shown in FIG. 1, a portion of a wall face 55 of the clean room 43 is
 brought into contact with the rear fender 25. This portion of the wall
 face 55 includes a recess groove 56. A projection 57 is provided on the
 side of the rear fender 25. The projection 57 mates with the recess groove
 56 to connect the rear fender 25 to the clean room 43. It should be noted
 that the relationship between the recess groove 56 and the projection 57
 may be reversed.
 FIG. 3 illustrates a water removing rib 58 formed on the upper face of the
 rear fender 25. FIG. 3 also illustrates a dust removing rib 59 formed on
 the upper face of the rear fender 25. FIG. 4 illustrates a breather pipe
 60 and a drain pipe 61.
 Next, an explanation will be given of the operation of the air cleaner, in
 accordance with the present invention. As shown in FIG. 1, outside air is
 sucked from the space 51 form between the rear face of the clean room 43,
 the front portion of the rear fender 25, and the bottom portion of the
 seat 7. The outside air is sucked in along a first flow direction
 extending through the intake port 50.
 The air enters the dirty room 44 on the lower side of the intake port 50.
 The air then changes its flow direction to a direction toward the center
 of the vehicle. Next, the air passes through the air cleaner element 41
 and enters into the clean room 43.
 Concerning one advantage of the present invention, the intake port 50
 extends in a widthwise direction of the vehicle. Therefore, the intake
 port 50 need not extend rearwardly, as in the background art. Since the
 length of the overall air cleaner, in the forwards-backwards direction
 (i.e. travel direction of the vehicle), is shortened by redirection of the
 intake port 50, it is possible to expand the relative sizes of the clean
 room 43 and the dirty room 44 if desired, while preserving, or even
 shortening, the length of the overall air cleaner. Even if the rooms 43,
 44 are expanded in size, a total length of the overall air cleaner in the
 forward and rearward direction and in an width extending to a side of the
 motorcycle, are reduced, resulting in making the air cleaner very compact.
 Concerning another advantage of the present invention, as illustrated in
 FIGS. 1 and 3, the air cleaner element 41 is a generally planar member
 which can be approximately arranged in a first plane which extends in the
 up and down (vertical) direction and forward and rearward (travel)
 direction. Accordingly, the surface area of the air cleaner element 41 is
 enlarged, relative to the background art. Therefore, the ventilation
 efficiency of the air cleaner is increased.
 Concerning yet another advantage of the present invention, outside air is
 sucked from the space 51 surrounded by the rear face of the clean room 43,
 the front portion of the rear fender 25 and the bottom portion of the seat
 7. Accordingly, invading water or dust is reduced, relative to the
 background art. Invading water and dust is even further reduced by the
 presence of the water removing rib 58 and the dust removing rib 59. By so
 locating and directing the air inlet, clogging of the air cleaner element
 41 becomes less likely, and easier to prevent.
 The invention being thus described, it will be obvious that the same may be
 varied in many ways. Such variations are not to be regarded as a departure
 from the spirit and scope of the invention, and all such modifications as
 would be obvious to one skilled in the art are intended to be included
 within the scope of the following claims.