The present invention relates to an air cleaner structure for a vehicle, which is suitable for a vehicle, such as a motorcycle, on which a V-type engine is mounted.

An air cleaner structure is publicly known, in which: an air cleaner is disposed above a V-type engine; an inlet portion is hanged into a V-bank valley positioned under the center of the bottom of the air cleaner; an air intake duct extending rearward from the vehicle front side is connected to the inlet portion; and suction funnels are extended downward in such positions as to sandwich the inlet portion and a filter element, which is connected to the inlet portion, from the front and rear thereof and are connected to front and rear cylinders, respectively (see Patent Document 1).

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2002-160686

In the above form in which the inlet portion is disposed in the V-bank valley and the air intake duct is connected there, it is necessary that the front and rear suction funnels be disposed in such positions as to sandwich the inlet portion and the filter element from the front and rear thereof, and that each of the funnels be extended long and downward. However, if the length of the funnel is made long in this way, the total height of an engine including the air cleaner becomes high because it is necessary to dispose an air cleaner box at an upper position in the vehicle correspondingly, so that the total height of the vehicle body can be high. Therefore, the present invention has an object to enable the air cleaner box to be disposed at a position as low as possible.

Patent document EP 1520 978 A2 relates to air cleaners which incorporate throttle bodies therein. An air cleaner housing comprises an upper, filtered side and a lower unfiltered side partitioned by a partition wall. Intake funnel pipes project into the filtered side. An air cleaner element is provided on the front side relative to a hollow plenum above the intake funnel pipes.

Patent document US 4,364,340 , relates to an induction system for a vehicular engine having a surging tank equipped with suction funnels. The surging tank is further provided with an intake passage which has is terminal portion communicating with an upper portion of a casing which has its lower portion communicating with an air cleaner box.

Patent document JP 61-093264 shows an intake-air device in a motorcycle having an air-purifier disposed between intake-air pipes of an engine. The air-purifier is provided with a coupling pipe which self is connected to a coupling box also connected to inlets of said intake-air pipes.

Patent document US 4,799,569 relates to motorcycle carrying a fuel tank of large capacity thereon. The motorcycle also comprises a cleaner provided with a pair of outlets. Said outlets are connected through conduits, carburettors and intake manifolds to the cylinders of the engine, respectively.

Claim 1 concerning an air cleaner structure for a vehicle of the present application for solving the above problems is characterized in that, in a vehicle on which a V-type engine is mounted and in which an air cleaner is disposed above the engine, a plurality of suction funnels for sending cleaned air to each bank of cylinders of the V-type engine are disposed in an air cleaner box in such a manner that respective axes of the funnels intersect each other, and a tubular filter element is disposed so as to overlap one of the suction funnels.

Claim 2 is, in the above claim 1, characterized in that the filter element is vertically positioned, and is held by sandwiching the filter element by means of a vertically split air cleaner box from above and below.

Claim 3 is, in the above claim 1, characterized in that: the V-type engine is such that the banks of cylinders are disposed along a fore-and-aft direction; and the air cleaner is such that the filter element is disposed in the vehicle-body front side of the air cleaner box and that fresh air is introduced into the filter element from an opening provided in a front portion of the air cleaner box.

Claim 4 is, in the above claim 3, characterized by comprising an air intake duct curvedly extending from the opening provided in the air cleaner box toward the front of the vehicle body.

According to claim 1, since the suction passages can be made to have a substantially linear shape by allowing the axes of the plurality of suction funnels to intersect each other, the suction efficiency increases, and, at the same time, the total height of the air cleaner box can be lowered by virtue of the inclination of the suction funnels.

In addition, by disposing the suction funnels in the air cleaner box, it is made possible to lower the total height of the engine including the air cleaner box, and to lower the total height of the vehicle body.

Moreover, by disposing the filter element in such a manner that it overlaps one of the intersecting suction funnels, it is possible to utilize the space in the air cleaner box without waste.

According to claim 2, since the columnar filter element is vertically positioned, and is held by sandwiching the filter element by means of the vertically split air cleaner box from above and below, the filter element can be fixed only with the air cleaner box, and another supporting member becomes unnecessary.

According to claim 3, since the filter element is disposed in the vehicle-body front side of the air cleaner box, and fresh air is introduced from the opening provided in a front lower portion of the air cleaner box, it becomes unnecessary to house the air intake duct in the bank valley. Accordingly, it is possible to arrange the air cleaner box close to the engine correspondingly, and to lower the total height of the engine including the air cleaner box.

According to claim 4, since the air intake duct is provided, which is connected to the opening provided in the front portion of the air cleaner box and curvedly extends toward the front of the vehicle body, it is possible to dispose the air intake duct with good space efficiency, and to introduce the fresh air efficiently because the air intake duct can be made relatively short.

• Fig. 1 is a left side view of a motorcycle to which the present invention is applied.
• Fig. 2 is a side view showing the vicinity of an air cleaner in an enlarged manner.
• Fig. 3 is a diagram showing the planer configuration of the air cleaner.
• Fig. 4 is a perspective view of the air cleaner shown in a state where an upper case is removed.
• Fig. 5 is a diagram showing another embodiment, corresponding to Fig. 2.
• Fig. 6 is a diagram showing the another embodiment, corresponding to Fig. 3.

A description will be given below of an embodiment with reference to the drawings. Fig. 1 is a left side view of a motorcycle to which the present invention is applied. A left-right pair of front forks 2 supporting a front wheel 1 at lower end portions thereof are connected to a head pipe 3 at upper portions thereof, and are freely steerable by using a handlebar 4.

The head pipe 3 is attached to a front end of a main frame 5. The main frame 5 is extended in a left-right pair shape, opening rearward from the head pipe 3. A pivot plate 6 is attached to each of rear end portions of the main frame 5. The pivot plates 6 are provided in a left-right pair, each of which has a substantially L shape in a side view, and support both end portions of a pivot shaft 7 laid laterally therebetween. The main frame 5 and the pivot plates 6 constitute, of a body frame, a frame main-body portion supporting an engine.

A front end of a rear swing arm 8 is freely swingably supported by the pivot shaft 7. A rear wheel 9 is supported at rear ends of the rear swing arm 8. Below the main frame 5, the water-cooling 4-cycle front-rear-cylinder V-type engine 10 is disposed. The engine 10 is such as to drive the rear wheel 9 via a chain, and is supported by the main frame 5 and the pivot plates 6 as well as down tubes 11 extending rearward and obliquely downward from the head pipe 3.

Stays 12 protruding upward are provided in a left-right pair integrally to the respective rear portions of the left and right main frames 5. A rear cushion 13 being a constituent of a rear wheel suspension is connected between an upper face of a front portion of the rear swing arm 8 and the stays 12. In addition, a front end portion of a seat-rail upper portion 14 is attached to an upper portion of each of the stays 12. The seat-rail upper portions 14 support a two-seater seat 15. Reference numeral 16 indicates a seat-rail lower portion; 17, a rear cover; and 18, a side trunk.

A fuel tank 19 is disposed above the engine 10 to the front of the seat 15, and is supported by the main frame 5 and upper end portions of the stays 12. An air cleaner 20 is incorporated inside a front portion of the fuel tank 19, and supplies air to a front cylinder 23 and a rear cylinder 24 of the engine 10 after cleaning the outside air sucked from an air intake duct 21 through a filter element 22.

A front exhaust pipe 25 and a rear exhaust pipe 26 extend from the exhaust ports of the front and rear cylinders 23 and 24 respectively, gather under the engine 10, and are connected to a rear muffler 27. In front of the front cylinder 23, a radiator 28 is supported by the down tubes 11, and water-cools the front and rear cylinders 23 and 24. The front of the body is covered with a front cowl 29.

Fig. 2 is a side view showing the vicinity of the air cleaner 20 in an enlarged manner. An air cleaner box 30 being a constituent of the air cleaner 20 has a vertically split construction constituted of an upper case 31 and a lower case 32.

The upper case 31 has a substantially dome shape, and is housed in a downward open space 19a formed under the front of the fuel tank 19.

In the lower case 32, a first funnel 33 and a second funnel 34 are disposed with a space between them in the vehicle width direction, and are disposed so that a rear end portion and a lower end portion thereof overlap each other in a side view.

The first funnel 33 is disposed in such a forward-tilted manner as to be oriented rearward and obliquely downward from the vehicle front side. The lower end portion of the first funnel 33 protrudes downward from a bottom portion of the lower case 32 and is connected to a throttle body 35, which is an electronic fuel-supply system.

The throttle body 35 is a publicly known electronic fuel-supply system including a throttle valve provided therein and an injector which is an electronic fuel-injection valve. The lower end portion of the throttle body 35 is attached to an attachment seat 36 provided on the front face of the cylinder head of the rear cylinder 24, and is thereby connected to a suction port of the rear cylinder 24.

The second funnel 34 is similar, but it is disposed in such a backward-tilted manner as to be oriented forward and obliquely downward. The lower portion of the second funnel 34 protrudes from a bottom portion of the lower case 32, and is connected to a throttle body 37. The throttle body 37 is attached to an attachment seat 38 provided on the back face of the cylinder head of the front cylinder 23, and is thereby connected to a suction port of the front cylinder 23. The attachment seats 36 and 38 are protrudingly arranged so as to face a bank valley 39 sandwiched by the front cylinder 23 and the rear cylinder 24 from the front and rear thereof, being disposed by utilizing the space of the bank valley 39.

C1 and C2 are central axes of the first and second funnels 33 and 34, intersecting in a substantially X shape above the bank valley 39. The suction passages for the suction ports of the front and rear cylinders 23 and 24 are formed substantially linearly along these axes C1 and C2.

From a front bottom portion of the lower case 32, the air intake duct 21 with a relatively short pipe length protrudes downward in a substantially L shape. Specifically, a duct upper portion 21a is fitted in an opening 40 provided in the front bottom portion of the lower case 32 at a position more forward than the first funnel 33, and is thereby connected to a through hole 43 (see Fig. 4) of the filter element 22 fixed in the air cleaner box 30 so as to communicate therewith from below. At the same time, a duct lower portion 21b curvedly protrudes from the duct upper portion 21a downward and forward. The tip of the duct lower portion 21b becomes substantially horizontal above the front cylinder 23, and opens forward substantially on the body center line (see Fig. 3).

The air intake duct 21 sucks the wind caused by traveling coming from the front of the body in the vicinity of the body center line where wind pressure is high, and introduces the wind into the air cleaner box 30 through the space above the front cylinder 23. The outside air introduced from the air intake duct 21 into the air cleaner box 30 is cleaned through the filter element 22, and thereafter branches into the first and second funnels 33 and 34 and is sent to the corresponding throttle bodies 35 and 37. Furthermore, the outside air is sent to the respective suction ports of the front and rear cylinders 23 and 24.

Fig. 3 is a diagram schematically showing the planer configuration of the air cleaner 20. The air cleaner 20 is so disposed that almost whole of the air cleaner 20 except for a front portion thereof overlaps a front portion of the fuel tank 19. The filter element 22 has an elliptical shape in a plan view shown in the drawing. The filter element 22 is disposed so as to be oriented laterally in the vehicle width direction, and is disposed so as to be offset to the vehicle right side of the body center line C.

In a space positioned on the vehicle left side of the body center line C in the air cleaner 20, the first funnel 33 is disposed so as to be long in the fore-and-aft direction. The front end portion of the first funnel 33 overlaps the filter element 22 when viewed along the vehicle width direction, and the rear end portion thereof substantially coincides with the position of the lower end portion of the second funnel 34 when viewed along the vehicle width direction.

The second funnel 34 is disposed at a substantially vertical inclination so as to be disposed side by side with the filter element 22 to the rear thereof along the fore-and-aft direction, in a vehicle right-side portion of the air cleaner 20. The air cleaner 20 is asymmetric in the vehicle width direction, expanding in such a manner that the vehicle right-side portion thereof is larger in volume. Note that each of the center axes C1 and C2 of the first and second funnels 33 and 34 is inclined so as to intersect the body center line C obliquely in a plan view.

Fig. 4 is a perspective view of the air cleaner 20 shown in a state where the upper case 31 is removed. A substantially columnar attachment boss 41 is integrally formed at the center of the bottom of the lower case 32 so as to protrude upward, and the center of the upper case 31 is fastened thereto via a bolt. The first and second funnels 33 and 34 are disposed along the vehicle width direction with the attachment boss 41 interposed therebetween.

Attachment portions 42a are formed at appropriate intervals in an attachment flange 42 formed around the lower case 32, to which the periphery of the upper case 31 is attached via screws. By fixing the upper case 31 to the lower case 32 thereover in this way, the upper portion of the filter element 22 is fixed, pressed by the upper case 31. Accordingly, when the upper case 31 is removed, the filter element 22 becomes removable.

The through hole 43 is formed through the center of the filter element 22. The space in the through hole 43 is a dirty side 45 communicating with the air intake duct 21. The filter element 22 is vertically disposed with the through hole 43 oriented along an up-and-down direction. The space in the air cleaner 20 surrounding the filter element 22 is a clean side 46. The outside air introduced from the air intake duct 21 enters the dirty side 45. The air then passes through the filter element 22 while being cleaned, and enters the clean side 46. Thereafter, the air flows into the first and second funnels 33 and 34.

Next, a description will be given of operations. As shown in Fig. 2, the outside air is introduced from the front of the vehicle above the front cylinder 23, cleaned by passing through the filter element 22, and then sent to the suction ports of the front and rear cylinders 23 and 24 from the first and second funnels 33 and 34. In this case, the suction passages are relatively short, having a substantially linear shape, so that it is possible to increase the suction efficiency.

In addition, since the air intake duct 21 is disposed above the front cylinder 23 outside the bank valley 39, almost the whole space within the bank valley 39 can be used as the space to dispose the throttle bodies 35 and 37. Accordingly, it is made possible to place the air cleaner 20 close to the front and rear cylinders 23 and 24, to lower the total height of the engine 10 including the air cleaner 20, and therefore to lower the vehicle height.

In addition, a relatively short one will suffice for the air intake duct 21, and, since the air intake duct 21 curves and opens to the vicinity of the body center line, the relatively cool outside air above the front cylinder 23 can be sucked at a position where wind pressure is high, so that it is possible to increase the suction efficiency. Moreover, by curving the air intake duct 21, it is possible to introduce the outside air from the body center line side even if the filter element 22 is offset to one side of the body, and it becomes easy to dispose the air intake duct 21 with the interference with the other components avoided and with good space efficiency. Furthermore, by connecting the air intake duct 21 to the opening 40 provided in the front side of the bottom of the lower case 32, it is made possible to ease the outside-air introduction to the vertically positioned filter element 22, and to install piping by effectively utilizing the space between the lower case 32 and the front cylinder 23.

In addition, since the first and second funnels 33 and 34 are disposed so as to be inclined individually so that the axes C1 and C2 intersect each other in a substantially X shape in a side view, the upward protruding amount of the funnels are reduced, and it is possible to lower the upper case 31 correspondingly. Therefore, also from this point, the air cleaner 20 can be disposed low.

Moreover, by disposing the filter element 22 in such a manner that it overlaps the first funnel 33 in a side view, it is possible to dispose the whole inside of the air cleaner 20 compactly.

Figs. 5 and 6 show another embodiment. Fig. 5 is a side view of the embodiment corresponding to Fig. 2, and Fig. 6 is a plan view thereof corresponding to Fig. 3. In this example, the filter element 22 is disposed laterally with the through hole oriented along the fore-and-aft direction, the front end portion thereof is attached to a lid 50, and the lid 50 is freely removably attached to a front face of the air cleaner box 30, so that the filter element 22 together with the lid 50 is removable. The arrangement of the first and second funnels 33 and 34 is similar to that in the previous embodiment.

The air intake duct 21 is attached to the front face of the air cleaner box 30. Specifically, the rear end of the air intake duct 21 is fitted in an opening 40 provided in the lid 50, and is thereby connected to the through hole of the filter element 22 so as to communicate therewith. At the same time, the air intake duct 21 extends forward, slightly curving toward the left side of the body. In addition, the front end thereof opens downward in the vicinity of the body center line above the radiator 28. A cooling fan 28a of the radiator 28 is located under the front end opening of the air intake duct 21.

With this configuration, a compact structure of the air cleaner 20 can be expected as in the case of the previous embodiment. At the same time, when the lid 50 is removed, it becomes possible to remove and replace the filter element 22 without removing the upper case 31. Accordingly, the air cleaner becomes excellent in terms of ease of maintenance.

In addition, a relatively short one, which extends forward from the front face of the air cleaner box 30, will suffice for the air intake duct 21, and the air intake duct 21 can open to the vicinity of the body center line by curving. Accordingly, the suction efficiency can be increased as in the case of the previous embodiment, and it becomes easy to dispose the air intake duct 21 with good space efficiency. Moreover, the outside-air introduction to the laterally positioned filter element 22 becomes easy.

It should be noted that the present invention is not limited to the above embodiments, and various modifications and applications thereof are also possible within the principle of the present invention. For example, the V-type engine includes not only one for a motorcycle but also one for various kinds of vehicles. In addition, the V-type engine includes not only a fore-and-aft bank type but also a lateral bank type. Accordingly, in some cases, the overlap between the suction funnel and the filter element would be exhibited not only in the side view but also in a view along the fore-and-aft direction. Moreover, it is sufficient for the filter element to have a tubular shape. The cross-sectional shape of the filter element may be an arbitrary shape, such as a circular shape or an elliptical shape.

10: engine, 19: fuel tank, 20: air cleaner, 21: air intake duct, 22: filter element, 23: front cylinder, 24: rear cylinder, 30: air cleaner box, 31: upper case, 32: lower case, 33: first funnel, 34: second funnel, 35: throttle body, 37: throttle body, 39: bank valley, 40: opening, 50: lid