TECHNICAL FIELD
[0001] The present invention relates to an air cleaner apparatus mounted on a straddle-type
vehicle. The invention also relates to a straddle-type vehicle equipped with the apparatus.
The present application claims priority from Japanese Patent Application No.
2011-289098, filed on December 28, 2012, which is incorporated by reference herein in its entirety.
BACKGROUND ART
[0002] In a straddle-type vehicle having an engine as a driving power source, dust or the
like contained in the air supplied to the engine may cause abrasion of the inside
of the engine, consequently leading to a shorter engine life span. For this reason,
an air cleaner, which is an apparatus for cleaning air, is generally provided on the
upstream side of the intake pipe for supplying air to the engine.
[0003] When the amount of dust contained in the air is large, the element (i.e., filter)
in the air cleaner case is clogged in a short time. To avoid the problem of the filter
clogging, it is conceivable that the size of the element is made larger. However,
as the size of the element is made larger, the size of the air cleaner accordingly
becomes larger, consequently causing the straddle-type vehicle such as a motorcycle
to have larger dimensions. In view of the problem, it has conventionally been known
that a dual element (that is, an element comprising two elements that are overlapped
with each other) is provided in the air cleaner case, in order to ensure the cleaning
performance for the air supplied to the engine and to prevent a size increase of the
air cleaner.
[0004] An air filter (air cleaner) of Patent Literature 1 has a filter case having an outer
tube and an inner tube. A wet-type prefilter is provided inside the inner tube. In
addition, a filter element is provided between the inner tube and the outer tube.
Accordingly, the air supplied into the filter case passes through the prefilter and
the filter element in that order. Large dust is captured by the prefilter, and small
dust is captured by the filter element. The air cleaner provided with such a dual
element is believed to be less likely to cause clogging than the air cleaner with
a single element.
CITATION LIST
Patent Literature
SUMMARY OF INVENTION
TECHNICAL PROBLEM
[0006] However, the technique disclosed in Patent Literature 1 has the following problem.
The supplied air needs to pass through the dual element. For this reason, the air
resistance is greater than the case that the air passes through a single element.
Another problem is as follows. In the dual element, the locations at which clogging
occurs are distributed between the prefilter and the filter element, but large dust
is captured in the prefilter, through which the supplied air passes first. For this
reason, the prefilter tends to cause clogging more easily than the filter element.
When clogging occurs in the prefilter, the air resistance in the prefilter becomes
high, so even if the clogging in the filter element is insignificant, the air resistance
of the air cleaner as a whole becomes high. As a consequence, the engine performance
deteriorates.
[0007] The present invention has been accomplished in view of the foregoing and other problems,
and an object thereof is to provide an air cleaner apparatus for a straddle-type vehicle
that has excellent air cleaning performance for the air supplied to the engine and
that inhibits the air resistance from increasing.
SOLUTION TO PROBLEM
[0008] The present invention provides an air cleaner apparatus comprising: an air cleaner
case for mounting to a straddle-type vehicle; a main filter element accommodated in
the air cleaner case and dividing an interior of the air cleaner case into a first
chamber and a second chamber; an intake passage for sucking air outside the air cleaner
case into the first chamber; a discharge passage for discharging the air within the
second chamber out of the air cleaner case; and a pre-filter element disposed in the
first chamber and comprising a wet-type element. The intake passage has an air outlet
port for blowing off the air into the first chamber, and the pre-filter element is
disposed spaced apart from the air outlet port so as to be positioned on an axis line
of the air outlet port.
[0009] In the air cleaner apparatus according to the present invention, the air sucked from
the outside of the air cleaner case passes through the intake passage and flows from
the air outlet port into the first chamber. Because the pre-filter element is disposed
spaced apart from the air outlet port so as to be positioned on the axis line of the
air outlet port, at least part of the air sucked into the first chamber hits the pre-filter
element. As a result, large dust contained in the air strikes the pre-filter element
and thereafter falls off. This inhibits the pre-filter element from being clogged
by the large dust. Therefore, the pre-filter element is unlikely to be clogged. On
the other hand, relatively small dust may be captured by the pre-filter element when
it strikes the pre-filter element. For this reason, if the air is kept sucked from
the outside of the air cleaner case, it is possible that the small dust may cause
clogging to some degree in the pre-filter element. Nevertheless, the air resistance
can be inhibited from increasing even if some clogging occurs in the pre-filter element,
because the air sucked from outside can pass through the main filter element without
passing through the pre-filter element. The air hits the pre-filter element and thereafter
passes through the main filter element disposed between the first chamber and the
second chamber. As a result, small dust or the like that has not been captured by
the pre-filter element can be captured by the main filter element.
[0010] Thus, since the air cleaner apparatus according to the present invention has excellent
air cleaning performance for the air supplied to the engine and is capable of inhibiting
the air resistance from increasing, the air cleaner apparatus can effectively prevent
the engine performance from degrading.
[0011] In one embodiment of the present invention, the air cleaner case has an opposing
wall facing the air outlet port and not allowing air to pass therethrough. The pre-filter
element is provided on the opposing wall.
[0012] Thus, the above-described advantageous effects can be obtained with the simple structure
of providing the pre-filter element on the opposing wall.
[0013] In one embodiment of the present invention, the opposing wall faces the main filter
element in the first chamber.
[0014] The main filter element and the pre-filter element are disposed at such positions
that they oppose each other in the first chamber in this way, so most of the air sucked
from outside is allowed to hit the pre-filter element first. As a result, the air
can be cleaned in good condition.
[0015] In one embodiment of the present invention, the pre-filter element is detachably
mounted to the opposing wall.
[0016] This makes it possible to replace the pre-filter element easily when clogging occurs
in the pre-filter element and the cleaning performance of the pre-filter element degrades.
In other words, maintenance of the pre-filter element can be carried out easily.
[0017] In one embodiment of the present invention, the pre-filter element is mounted directly
to the opposing wall.
[0018] This eliminates the need for the complicated structure for mounting the pre-filter
element to the opposing wall, and can simplify the structure of the air cleaner apparatus.
[0019] In one embodiment of the present invention, the air cleaner case has a hook member
protruding from the opposing wall. The pre-filter element is hooked on the hook member.
[0020] As a result, the pre-filter element can be attached to and detached from the opposing
wall easily. In other words, maintenance of the pre-filter element can be carried
out easily.
[0021] In one embodiment of the present invention, the pre-filter element is provided on
a portion of the opposing wall.
[0022] By disposing the pre-filter element on a portion of the opposing wall that the air
sucked from outside can hit easily (typically a portion thereof near the air outlet
port) in this way, cleaning of air can be carried out with a pre-filter element having
a smaller size.
[0023] In one embodiment of the present invention, the opposing wall extends in a vertical
direction.
[0024] Thus, large dust contained in the air that has been sucked from outside falls off
after it strikes the pre-filter element provided on the wall extending in a vertical
direction. That is, large dust can be removed more effectively.
[0025] In one embodiment of the present invention, the air outlet port is disposed between
the main filter element and the pre-filter element.
[0026] Thus, the main filter element and the pre-filter element are disposed at opposing
positions across the air outlet port, so most of the air sucked from outside is allowed
to hit the pre-filter element first. As a result, the air can be cleaned in good condition.
[0027] In one embodiment of the present invention, the pre-filter element has a surface
area greater than the maximum flow passage cross-sectional area of the intake passage.
[0028] Since the pre-filter element has a greater surface area in this way, the air blown
off from the air outlet port is allowed to hit the pre-filter element sufficiently.
As a result, the air sucked from outside can be cleaned in good condition by the pre-filter
element.
[0029] In one embodiment of the present invention, the main filter element has a surface
area greater than the surface area of the pre-filter element.
[0030] Thereby, the air sucked from outside can be preliminarily cleaned in the pre-filter
element by causing large dust to fall off at the pre-filter element and at the same
time small dust to be captured in the pre-filter element, and thereafter, the air
is cleaned sufficiently in the main filter element.
[0031] In one embodiment of the present invention, the main filter element comprises a dry-type
element.
[0032] This makes handling and maintenance of the main filter element easy.
[0033] In one embodiment of the present invention, the air outlet port opens in a direction
that does not intersect the main filter element.
[0034] This reduces the air sucked from outside that directly hits the main filter element.
[0035] In one embodiment of the present invention, the air outlet port opens in a direction
that intersects the pre-filter element.
[0036] This enables most of the air that is sucked from outside to directly hit the pre-filter
element.
[0037] A straddle-type vehicle according to the present invention may comprise the above-described
air cleaner apparatus.
[0038] The present invention makes it possible to obtain a straddle-type vehicle that exhibits
the above-described advantageous effects.
ADVANTAGEOUS EFFECTS OF INVENTION
[0039] As described above, the present invention can provide an air cleaner apparatus for
a straddle-type vehicle that has excellent air cleaning performance for the air supplied
to the engine and that inhibits the air resistance from increasing.
BRIEF DESCRIPTION OF DRAWINGS
[0040]
Fig. 1 is a right side view illustrating a motorcycle according to one embodiment
of the present invention;
Fig. 2 is a front view illustrating a rear portion of the motorcycle according to
one embodiment of the present invention;
Fig. 3 is a rear view illustrating the rear portion of the motorcycle according to
one embodiment of the present invention;
Fig. 4 is a plan view illustrating the rear portion of the motorcycle according to
one embodiment of the present invention;
Fig. 5 is a left side view illustrating the rear portion of the motorcycle according
to one embodiment of the present invention;
Fig. 6 is a right side view illustrating the rear portion of the motorcycle according
to one embodiment of the present invention;
Fig. 7 is a perspective view illustrating an air cleaner and a storage box according
to one embodiment of the present invention;
Fig. 8 is an internal cross-sectional view illustrating an engine unit according to
one embodiment of the present invention;
Fig. 9 is a plan view illustrating an air cleaner and a rear fender according to one
embodiment of the present invention;
Fig. 10 is a left side view illustrating the air cleaner and the rear fender according
to one embodiment of the present invention;
Fig. 11 is a right side view illustrating the air cleaner and the rear fender according
to one embodiment of the present invention;
Fig. 12 is a horizontal cross-sectional view illustrating the air cleaner according
to one embodiment of the present invention;
Fig. 13 is a cross-sectional view taken along line XIII-XIII in Fig. 12; and
Fig. 14 is a horizontal cross-sectional view illustrating an air cleaner according
to another embodiment of the present invention.
DESCRIPTION OF EMBODIMENTS
[0041] Hereinbelow, embodiments of the present invention will be described. As illustrated
in Fig. 1, the straddle-type vehicle according to the present embodiment is a scooter
type motorcycle 1. The type of the straddle-type vehicle according to the present
invention is, however, not limited to the scooter type motorcycle 1. The straddle-type
vehicle according to the present invention may be any other type of motorcycle, such
as a moped type motorcycle, an off-road type motorcycle, or an on-road type motorcycle.
The straddle-type vehicle according to the present invention is not limited to a motorcycle
but may be any other straddle-type vehicle, such as ATV (All Terrain Vehicle). Note
that the straddle-type vehicle means a vehicle such that the rider straddles the vehicle
when riding.
[0042] In the following description, the terms "front," "rear," "left," and "right" respectively
refer to front, rear, left, and right as defined based on the perspective of the rider
of the motorcycle 1. Reference characters F, Re, L, and R in the drawings indicate
front, rear, left, and right, respectively.
[0043] The motorcycle 1 has a vehicle body 5, a front wheel 7, a rear wheel 9, and an engine
unit 40 for driving the rear wheel 9. The vehicle body 5 has a handlebar 11, which
is operated by the rider, and a seat 13, on which the rider is to be seated. The engine
unit 40 is what is called a unit swing type engine unit that has an engine 42 (see
Fig. 8). The front end portion of the engine unit 40 is supported by a body frame
20 so that the engine unit can swing about a pivot shaft 38, which is a horizontal
axis. That is, the engine unit 40 is supported so as to be swingable relative to the
body frame 20.
[0044] The body frame 20 has a main frame 24 extending rearward and obliquely downward from
a head pipe 22, left and right seat frames 26 (see Fig. 2) and 28 extending rearward
and obliquely upward from the main frame 24, and a cross-member 30 (see Fig. 2) provided
between the left and right seat frames 26 and 28. A front fork 32 is mounted to the
head pipe 22.
[0045] A front wheel 7 is supported at a lower end portion of the front fork 32. A rear
wheel 9 is supported at a rear end portion of the engine unit 40. A rear fender 80
for covering a portion of the rear wheel 9 is supported on the engine unit 40. The
air cleaner 80 can swing relative to the body frame 20, together with the rear wheel
9.
[0046] As illustrated in Fig. 4, the motorcycle 1 has a storage box 180 between the left
and right seat frames 26 and 28, which is supported by the cross-member 30. The storage
box 180 has dimensions such as to accommodate a helmet or the like. An opening is
formed in an upper portion of the storage box 180. The seat 13 (see Fig. 1) is configured
to be pivotable about the front end portion of the seat 13. When the seat 13 is pivoted
so that the rear end portion of the seat 13 moves frontward and obliquely upward,
the just-mentioned opening is exposed outside. As illustrated in Fig. 5, the storage
box 180 has a left side wall 192 positioned to the right of the left seat frame 26.
Also, the storage box 180 has a right side wall 182 positioned to the left of the
right seat frame 28, as illustrated in Fig. 6.
[0047] As illustrated in Figs. 4 and 5, the motorcycle 1 has a passenger footrest 35 supported
on a rear portion of the left seat frame 26 (for example, near the upper portion of
the rear wheel 9 when viewed from side). Of the right seat frame 28 and the left seat
frame 26, only the left seat frame 26 is provided with the passenger footrest 35..
The footrest 35 has a relatively large footrest face 36 (see also Fig. 4). The passenger
seated on the seat 13 can put both of his/her feet on the footrest 35.
[0048] It is sufficient that the footrest 35 is supported on a rear portion of only one
of the left seat frame 26 and the right seat frame 28. The footrest 35 may be supported
on a rear portion of the right seat frame 28. However, it is more preferable that
the footrest 35 be supported on a rear portion of the left seat frame 26 because,
in that way, the passenger can avoid the heat emitted from a muffler 15. Thus, it
is preferable that the footrest 35 be provided on one of the left and right seat frames
that is opposite the one on which the muffler 15 is provided.
[0049] The engine unit 40 is supported by the body frame 20 below the storage box 180. As
illustrated in Fig. 8, the engine unit 40 has an engine 42, which is one example of
an internal combustion engine, and a V-belt type continuously variable transmission
(hereinafter referred to as "CVT") 62. The engine 42 has a crankcase 44, a cylinder
block 48 extending frontward and obliquely upward from the crankcase 44, a cylinder
head 50 connected to a front portion of the cylinder block 48, and a cylinder head
cover 52 connected to a front portion of the cylinder head 50. In the present specification,
the entirety of the cylinder block 48, the cylinder head 50, and the cylinder head
cover 52 is collectively called a cylinder 46. The cylinder 46 extends frontward and
obliquely upward from the crankcase 44. A transmission case 60 is disposed to the
left of the crankcase 44. The CVT 62 is disposed in the transmission case 60.
[0050] A recessed portion 53, and an intake port and an exhaust port (not shown) that are
connected to the recessed portion 53 are formed in the cylinder head 50. An intake
pipe 54 (see Fig. 6) is connected to the intake port, and an exhaust pipe 56 (see
Fig. 6) is connected to the exhaust port. Note that the intake pipe 54 herein is not
limited to a single component but may include one comprising a plurality of components
combined together. For example, the intake pipe 54 may be formed by a combination
of a pipe connected to the intake port, a throttle body connected to the pipe, a duct
connected to the throttle body, and so forth. The top face of a piston 59, the inner
circumferential wall of the cylinder block 48, and the recessed portion 53 together
form a combustion chamber 57. The piston 59 is connected to a crankshaft 45 via a
connecting rod 58. The crank shaft 45 extends leftward and rightward. The crank shaft
45 is accommodated in the crankcase 44.
[0051] The CVT 62 has a first pulley 64, which is a driving pulley, a second pulley 66,
which is a driven pulley, and a V-belt 68 wrapped around the first pulley 64 and the
second pulley 66. A left end portion of the crankshaft 45 protrudes to the left from
the crankcase 44. The first pulley 64 is fitted to the left end portion of the crankshaft
45. The second pulley 66 is fitted to a main shaft 70. The main shaft 70 is connected
to a rear wheel shaft 72 via a gear mechanism, which is not shown in the drawings.
Note that Fig. 8 depicts the state in which the transmission ratio for a front portion
of the first pulley 64 and that for a rear portion of the first pulley 64 are different
from each other. The second pulley 66 has the same configuration.
[0052] The intake pipe 54 is connected to the intake port of the cylinder head 50. The intake
pipe 54 extends rearward from the cylinder head 50. As illustrated in Fig. 6, the
intake pipe 54 is disposed above the cylinder 46 and below the storage box 180. An
air cleaner 100 is connected to a rear portion of the intake pipe 54.
[0053] The exhaust pipe 56 is connected to the exhaust port of the cylinder head 50. The
exhaust pipe 56 extends rearward from the cylinder head 50. The muffler 15 extending
rearward and obliquely upward is connected to a rear end portion of the exhaust pipe
56.
[0054] As illustrated in Fig. 12, an air cleaner apparatus 102 according to the present
embodiment has the air cleaner 100, a later-described discharge passage 148, and an
air inlet unit 120. The air cleaner 100 has an air cleaner case 105. The air cleaner
case 105 is provided with the air inlet unit 120. The air inlet unit 120 has an air
inlet port 122 for sucking air and an intake passage 130 extending upward from the
air cleaner case 105. As illustrated in Fig. 3, the intake passage 130 is disposed
to the right of the vehicle center line L1. The air inlet port 122 of the intake passage
130 is disposed to the right of the right side wall 182 of the storage box 180 and
to the left of the right seat frame 28. At least a portion of the air inlet port 122
of the intake passage 130 opens toward the right side wall 182 of the storage box
180. In the present embodiment, the intake passage 130 is formed so as to extend frontward,
or frontward and obliquely upward. However, the intake passage 130 may extend vertically
upward, or frontward and obliquely downward.
[0055] It should be noted that in the present specification, the term "vehicle center line"
means the line that, as viewed in plan, passes through the lateral (widthwise) center
of the front wheel 7 and the lateral (widthwise) center of the rear wheel 9 and extends
in a longitudinal direction (a front-rear direction).
[0056] As illustrated in Fig. 6, a cover 15A having a plurality of slits 17 formed therein
is fitted to the muffler 15. The slits 17 are formed in a front portion of the cover
15A. Each of the slits 17 extends frontward and obliquely downward. The slits 17 are
aligned one above the other and arranged parallel to each other. When the motorcycle
1 is running, there is a risk the water on the ground may be splashed up by the front
wheel 7, hits the cover 15A, and thereafter scatters upward. However, by providing
the slits 17, it is possible to change the direction in which the water splashed up
by the front wheel 7 runs. This effectively inhibits the water splashed up by the
front wheel 7 from hitting the cover 15A and entering the air inlet port 122 of the
air cleaner apparatus 102. In addition, after having been momentarily captured by
the slits 17, the splashed water becomes easy to flow rearward along the surface of
the cover 15A. For this reason, the cover 15A can be cooled by this water. Thus, the
muffler 15 that has become hot can be cooled indirectly, and also, the muffler 15
can be cooled effectively.
[0057] In the present embodiment, as illustrated in Fig. 3, the center line L2 of the muffler
15 is positioned to the right of the center line L3 of the intake passage 130, when
viewed from the rear the motorcycle (vehicle) 1. Preferably, the leftmost end 16 of
the muffler 15 is positioned to the right of the center line L3 of the intake passage
130 when viewed from the rear of the vehicle. More preferably, the leftmost end 16
of the muffler 15 is positioned to the right of the rightmost end of the intake passage
130 when viewed from the rear of the vehicle. Such a configuration makes it possible
to effectively inhibit the heat of the muffler 15 from being transmitted to the intake
passage 130, which is connected to the air cleaner 100 and the air cleaner 100.
[0058] In the present specification, the term "the center line of the muffler 15" refers
to the line that, as viewed in plan, passes through the lateral (widthwise) center
of the muffler 15 and extends in a longitudinal direction (a front-rear direction).
Likewise, In the present specification, the term "the center line of the intake passage
130" refers to the line that, as viewed in plan, passes through the lateral (widthwise)
center of the intake passage 130 and extends in a longitudinal direction (a front/rear
direction). In Fig. 3, for convenience in illustration, the vertical lines passing
the center lines L1, L2, and L3 are indicated by dash-dotted lines, which are denoted
by respective reference characters L1, L2, and L3, in place of the center lines L1,
L2, and L3.
[0059] As illustrated in Fig. 5, the motorcycle 1 has a rear cushion unit 95 provided between
a rear portion of the body frame 20 (typically a rear portion of the left seat frame
26) and a rear portion of the engine unit 40. The rear cushion unit 95 is supported
by the left seat frame 26 and the transmission case 60.
[0060] As illustrated in Fig. 9, the air cleaner 100 is connected to the intake pipe 54
for introducing air to the engine unit 42. In the present embodiment, a connecting
portion 43 of the intake pipe 54 for connecting the intake pipe 54 to the engine 42
and a connecting portion 55 of the intake pipe 54 for connecting the intake pipe 54
to the air cleaner 100 (second case 140) are disposed on the vehicle center line L1,
as viewed in plan. With such a configuration, the intake pipe 54 has no or, if any,
a little bend in a right/left direction. Therefore, the air-intake characteristics
of the engine 42 are good, and the engine performance improves. In other words, the
intake pipe 54 is allowed to extend straight as viewed in plan, so the air-intake
resistance can be reduced and the engine performance can be improved.
[0061] The rear fender 80 has an upper portion 82 positioned above the rear wheel 9 and
side portions 84A and 84B positioned to the sides of the rear wheel 9. The air cleaner
100 forms at least a portion of the upper portion 82 of the rear fender 80. As illustrated
in Figs. 6 and 11, the air cleaner 100 (first case 110) and the rear wheel 9 are disposed
so as to overlap each other as viewed from side.
[0062] The front-to-rear length of the right side portion of the air cleaner 100 is set
longer than the front-to-rear length of the left side portion thereof. The air inlet
unit 120 is provided for one of the left and right side portions of the air cleaner
100 with respect to the vehicle center line L1 that has a longer front-to-rear length
than the other. In the present embodiment, the air inlet unit 120 is provided on the
right side portion (the later-described first case 110) of the air cleaner 100.
[0063] As illustrated in Fig. 12, the air cleaner 100 has the air cleaner case 105 including
a first case 110 and a second case 140 each having an opening formed therein, and
a main filter element 170 for cleaning air. The first case 110 and the second case
140 are assembled to each other so that their openings face each other with the main
filter element 170 interposed therebetween. Thus, the main filter element 170 is accommodated
in the air cleaner case 105 so that it divides the interior of the air cleaner case
105 into a first chamber 115 (i.e., the internal space of the first case 110) and
a second chamber 145 (i.e., the internal space of the second case 140). The main filter
element 170 may be either a dry-type element (an element not impregnated with oil)
or a wet-type element (an element impregnated with oil).
[0064] In the present specification, the phrase "the main filter element 170 divides the
interior of the air cleaner case 105 into the first chamber 115 and the second chamber
145" means to include not only a case in which the main filter element 170 forms the
entire dividing wall but also a case in which the main filter element 170 forms a
portion of the dividing wall.
[0065] The main filter element 170 is fitted to a frame 174. The main filter element 170
can be easily fitted into the case 105 together with the frame 174 by respectively
fitting engaging portions 176, 176 formed on both end portions of the frame 174 into
engaging grooves 106, 106 provided in the air cleaner case 105. In addition, in case
that the main filter element 170 needs to be replaced, the main filter element 170
can be easily removed, so the maintenance can be carried out easily.
[0066] The above-described air inlet unit 120 is connected to the first case 110. More specifically,
the first case 110 of the air cleaner 100 is provided with the air inlet unit 120
for sucking the air outside the air cleaner case 105 into the first chamber 115. As
described previously, the air inlet unit 120 has the air inlet port 122 for sucking
air and the intake passage 130 extending upward from the air cleaner case 105 (more
specifically from the first case 110). As illustrated in Fig. 13, the intake passage
130 has an air outlet port 132 for blowing off air into the first chamber 115. As
illustrated in Fig. 12, the air outlet port 132 opens in a direction that intersects
a pre-filter element 138. The air outlet port 132 opens in a direction that does not
intersect the main filter element 170.
[0067] As illustrated in Figs. 12 and Fig. 13, the pre-filter element 138 comprising a wet-type
element (that is, an element impregnated with oil) is disposed in the first chamber
115. The pre-filter element 138 is disposed spaced apart from the air outlet port
132 so as to be positioned on the axis line of the air outlet port 132. The pre-filter
element 138 is disposed so that the blown-off air can hit the pre-filter element 138
but does not pass through the pre-filter element 138.
[0068] In the present specification, the phrase "air passes through the pre-filter element
138" means that the air passes through the pre-filter element 138 without substantially
changing its flow direction. Therefore, such an air flow that hits the pre-filter
element 138 in the front and leaks from the side faces of the pre-filter element 138,
not flowing out from the back face of the pre-filter element 138, does not fit the
definition of the phrase "air passes through the pre-filter element" herein.
[0069] As indicated by the dash-dot-dot line X in Fig. 13, it is preferable that the air
outlet port 132 be disposed so that the air outlet port 132 faces a central portion
of the pre-filter element 138. In other words, it is preferable that the air outlet
port 132 be disposed so that the central region of the pre-filter element 138 is positioned
on an extension line of the air outlet port 132. In the present embodiment, the air
outlet port 132 is disposed between the main filter element 170 and the pre-filter
element 138, as illustrated in Fig. 12. It is preferable that the air outlet port
132 be disposed so that the pre-filter element 138 is positioned on an extension line
of at least a portion of the air outlet port 132. It is more preferable that the air
outlet port 132 be disposed so that the pre-filter element 138 is positioned on the
extension line of the air outlet port 132. In addition, it is preferable that the
distance between the air outlet port 132 and the pre-filter element 138 be shorter
than the distance between the air outlet port 132 and the main filter element 170.
Such a configuration allows the air outside the air cleaner to hit the pre-filter
element 138 more effectively.
[0070] It is preferable that the surface area of the pre-filter element 138 be greater than
the opening area of the air outlet port 132. In addition, it is preferable that the
pre-filter element 138 has a surface area greater than the maximum flow passage cross-sectional
area of the intake passage 130. Such a configuration allows the air blown off from
the air outlet port 132 to hit the pre-filter element 138 sufficiently because the
surface area of the pre-filter element 138 is greater. As a result, the air sucked
from outside can be cleaned in good condition by the pre-filter element 138.
[0071] In the present specification, the term "the surface area of the pre-filter element
138" means the area of the surface of the pre-filter element 138 that is exposed to
the first chamber 115 and it does not include the area thereof that is in contact
with an opposing wall 136.
[0072] It is preferable that the surface area of the main filter element 170 be greater
than the surface area of the pre-filter element 138. Such a configuration allows large
dust to fall off at the pre-filter element 138 and at the same time relatively small
dust to be captured in the pre-filter element 138, so that the air sucked from outside
can be preliminarily cleaned. Thereafter, the air can be further cleaned in the main
filter element 170.
[0073] In the present specification, the term "the surface area of the main filter element
170" means the entire surface area of the main filter element 170 with which the air
can be in contact when the air passes from the first chamber 115 to the second chamber
145.
[0074] The first case 110 of the air cleaner 100 has an opposing wall 136 facing the air
outlet port 132 and not allowing air to pass therethrough. The opposing wall 136 faces
the main filter element 170 in the first chamber 115. The opposing wall 136 extends
in a vertical direction. The pre-filter element 138 provided on the opposing wall
136 is disposed so as to extend in a vertical direction. Large dust contained in the
air sucked from outside tends to fall off after it strikes the pre-filter element
138. As a result, large dust is not captured by the pre-filter element 138 in a large
amount, so the pre-filter element 138 is inhibited from clogging.
[0075] In the present embodiment, the first case 110 of the air cleaner 100 has hook members
134, 134 protruding from the opposing wall 136. The pre-filter element 138 is hooked
on the hook members 134, 134, whereby the pre-filter element 138 is provided on the
opposing wall 136. As illustrated in Fig. 12, the hook members 134 are fitted in fitting
holes 139 formed in the pre-filter element 138 so that the pre-filter element 138
can be mounted onto the opposing wall 136. Such a configuration makes the maintenance
of the pre-filter element 138 easy.
[0076] In the present embodiment, the pre-filter element 138 is detachably mounted to the
opposing wall 136 by being hooked on the hook members 134, 134, but the method of
mounting the pre-filter element 138 to the opposing wall 136 is not particularly limited.
For example, the pre-filter element 138 may be mounted directly to the opposing wall
136 by using, for example, an adhesive agent.
[0077] In addition, an example of a modified embodiment is shown in Fig. 14, in which a
pre-filter element 238 is fitted into and removed from a slot 116 provided in a front
end portion of the first case 110. The pre-filter element 238 inserted from the slot
116 into the first chamber 115 is prevented from moving in the frontward and rearward
directions by a positioning wall 118 formed in the first chamber 115. In addition,
the pre-filter element 238 is prevented from moving in the leftward and rightward
directions by a positioning wall 117 formed in the first chamber 115. When the pre-filter
element 238 is fitted in the first chamber 115, the slot 116 is closed by a lid or
the like so that the outside air does not flow in through the slot 116.
[0078] In the present embodiment, the pre-filter element 138 is provided on a portion of
the opposing wall 136 (that is, near the air outlet port 132), but this configuration
is merely illustrative. For example, the pre-filter element 138 may be provided over
the entire surface of the opposing wall 136. Alternatively, the pre-filter element
138 may be provided on a wall that makes up the first chamber 115 but does not oppose
the main filter element 170 (i.e., a different wall from the opposing wall 136).
[0079] The second case 140 of the air cleaner 100 is provided with the discharge passage
148 for discharging the air within the second chamber 145 out of the air cleaner case
105. In the present embodiment, the discharge passage 148 constitutes a part of the
intake pipe 54 that allows the second case 140 of the air cleaner 100 to communicate
with the engine 42.
[0080] In the air cleaner apparatus 102, the air outside the air cleaner case 105 is sucked
from the air inlet port 122. The sucked air passes through the intake passage 130
and flows from the air outlet port 132 toward a central portion of the pre-filter
element 138. When the sucked air strikes the pre-filter element 138, large dust contained
in the air falls off into the first chamber 115. On the other hand, a portion of small
dust contained in the air is not captured by the pre-filter element 138 and is allowed
to flow, while the other portion thereof is captured by the pre-filter element 138.
Thus, the air is cleaned by the pre-filter element 138.
[0081] Meanwhile, as the small dust is kept captured by the pre-filter element 138, clogging
may occur in the pre-filter element 138 to some degree. However, the air that has
been sucked in the first chamber 115 can pass through the main filter element 170
without passing through the pre-filter element 138. In addition, the sucked air strikes
the surface of the pre-filter element 138 and changes its flow direction. Therefore,
the increase of the air resistance resulting from the clogging can be inhibited.
[0082] The air cleaned by the pre-filter element 138 thereafter passes through the main
filter element 170. At this time, the small dust that was not captured by the pre-filter
element 138 is captured by the main filter element 170. As a result, the air that
has been cleaned in good condition can be supplied to the engine 42.
[0083] Next, the air inlet port 122 of the intake passage 130 will be described in detail.
As illustrated in Figs. 6 and 7, at least a portion of the air inlet port 122 of the
intake passage 130 faces the right side wall 182 of the storage box 180.
[0084] In the present embodiment, the intake passage 130 is formed by a duct that cannot
contract or expand. In such a configuration, the length of the intake passage 130
is invariable, and accordingly, the length of the whole intake passage of the engine
42 (that is, the intake passage 130 of the air inlet unit 120, the passage in the
air cleaner 100, and the intake pipe 54) is invariable. As a result, fluctuations
in the intake pulse can be suppressed, and the performance of the engine 42 is stabilized.
[0085] As illustrated in Figs. 3 and 6, the right side wall 182 of the storage box 180 is
positioned to the left of the right seat frame 28. A recessed portion 190 recessed
toward the left is formed in the right side wall 182 of the storage box 180. The right
side wall 182 of the storage box 180 has a front side wall 184, a rear wall 186 extending
leftward from the rear end of the front side wall 184, and a rear side wall 188 extending
rearward from the leftmost end of the rear wall 186. The recessed portion 190 is defined
by at least the rear wall 186 and the rear side wall 188.
[0086] As illustrated in Figs. 3 and 5, the storage box 180 has the left side wall 192 positioned
to the right of the left seat frame 26. A recessed portion 200 recessed toward the
right is formed in the left side wall 192 of the storage box 180. The left side wall
192 of the storage box 180 has a front side wall 194, a rear wall 196 extending rightward
from the rear end of the front side wall 194, and a rear side wall 198 extending rearward
from the rightmost end of the rear wall 196. The recessed portion 200 is defined by
at least the rear wall 196 and the rear side wall 198.
[0087] As illustrated in Fig. 4, in the present embodiment, at least a portion of the air
inlet port 122 of the intake passage 130 is disposed within the recessed portion 190.
That is, as illustrated in Fig. 2, when viewed from the front of the motorcycle 1,
at least a portion of the air inlet port 122 is hidden behind the storage box 180
and cannot be seen. The mud, dust, water, and the like that are splashed up by the
front wheel 7 do not enter the recessed portion 190 easily. As a result, entry of
mud, dust, water and the like into the air inlet port 122 is inhibited.
[0088] Preferably, at least a portion of the air inlet port 122 of the intake passage 130
faces the rear wall 186. In the present embodiment, as illustrated in Fig. 7, the
air inlet port 122 of the intake passage 130 has a first portion 124 that opens frontward
and a second portion 126 that opens (i.e., has an opening) leftward. As illustrated
in Fig. 4, the air inlet port 122 is disposed so that the rightmost end 187 of the
rear wall 186 is positioned more to the right than the rightmost end 125 of the first
portion 124. The first portion 124 of the air inlet port 122 faces the rear wall 186
of the right side wall 182. The second portion 126 of the air inlet port 122 faces
the rear side wall 188 of the right side wall 182. By disposing the first portion
124 of the air inlet port 122 so as to face the rear wall 186 and disposing the second
portion 126 of the air inlet port 122 so as to face the rear side wall 188 in this
way, the advantageous effects of disposing the air inlet port 122 within the recessed
portion 190 can be obtained without reducing the size of the air inlet port 122. That
is, both ensuring sufficient housing space of the storage box 180 and preventing the
entry of dust into the air cleaner 100 can be achieved at the same time.
[0089] As illustrated in Fig. 9, the air inlet port 122 of the present embodiment has an
L-shape as viewed in plan, but is not limited to having such a shape. For example,
the air inlet port 122 may have a shape such as to open obliquely leftward and frontward.
[0090] The air inlet port 122 is disposed in the space between the right of the right side
wall 182 of the storage box 180 and the left of the right seat frame 28, which has
been an unutilized space in the past. Thus, it is not necessary to provide extra space
for the air inlet port 122, and it is possible to utilize the existing space effectively.
Moreover, the water, mud, dust, and the like that are splashed up from the front wheel
7 are unlikely to enter the air inlet port 122 because at least a portion of the air
inlet port 122 is disposed so as to face the right side wall 182 of the storage box
180. As a result, the amount of dust and the like sucked into the air cleaner 100
is reduced, so the performance deterioration of the engine 42 can be inhibited effectively.
[0091] Preferably, as illustrated in Fig. 6, at least a portion of the air inlet port 122
is disposed so as to overlap the right seat frame 28 when viewed from the side of
the vehicle. With such a configuration, entry of mud and dust into the air inlet port
122 can be inhibited by the right seat frame 28.
[0092] In the motorcycle 1 according to the present embodiment, the intake passage 130 connected
to the air cleaner 100 is disposed in the space between the right of the right side
wall 182 of the storage box 180 and the left of the right seat frame 28. For this
reason, another intake passage 210 extending upward from the transmission case 60
can be disposed to the left of the vehicle center line L1 so as not to interfere with
the intake passage 130 connected to the air cleaner 100, as illustrated in Figs. 3
and 5. In other words, the intake passage 210 can be disposed in the space between
the left of the left side wall 192 of the storage box 180 and the right of the left
seat frame 26.
[0093] The intake passage 210 is a passage for introducing cooling air to the CVT 62 in
the transmission case 60. As illustrated in Fig. 5, the intake passage 210 has a bellows-shaped
duct 214 that can freely contract and expand, and a duct 216 integrally formed with
the recessed portion 200 of the left side wall 192 of the storage box.
[0094] An air inlet port 212 that opens leftward is formed at a distal end portion of the
duct 216. At least a portion of the air inlet port 212 is disposed within the recessed
portion 200. The air inlet port 212 is an opening for sucking air. In the present
embodiment, the entirety of the air inlet port 212 is disposed within the recessed
portion 200. The air inlet port 212 opens toward the left from a rear side wall 198
of the left side wall 192. However, like the above-described air inlet port 122 of
the intake passage 130, it is sufficient that at least a portion of the air inlet
port 212 should face the rear wall 196. The mud, dust, water, and the like that are
splashed up by the front wheel 7 does not easily enter the recessed portion 200. As
a result, entry of mud, dust, water and the like through the air inlet port 212 into
the transmission case 60 can be inhibited.
[0095] Next, the rear fender 80 will be described in detail. As illustrated in Fig. 9, the
air cleaner 100 forms at least a portion of the upper portion 82 of the rear fender
80. In the present embodiment, a portion of the upper portion 82 of the rear fender
80 is formed by the second case 140. The first case 110 is disposed at a side of the
rear fender 80. By disposing the first case 110 at a side of the rear fender 80 in
this way, the second case 140 is ensured to have a large capacity.
[0096] The portion of the rear fender 80 excluding the air cleaner 100 (hereinafter referred
to as a "main fender portion 86") and the air cleaner 100 are assembled with each
other. As illustrated in Fig. 9, the main fender portion 86 and the second case 140
of the air cleaner 100 are fastened to each other by a fastener 90A in the upper portion
82 of the rear fender 80. As illustrated in Fig. 10, the main fender portion 86 and
the second case 140 of the air cleaner 100 are fastened to each other by a fastener
90B in the left side portion 84B of the rear fender 80. As illustrated in Fig. 11,
the main fender portion 86 and the first case 110 of the air cleaner 100 are fastened
to each other by a fastener 90C in the right side portion 84A of the rear fender 80.
Examples of the fasteners 90A to 90C in the present embodiment include commonly-used
bolts, screws, and rivets.
[0097] As illustrated in Fig. 5, the engine unit 40 and the air cleaner 100, which is a
part of the rear fender 80, are fastened to each other by a fastener 92A. As illustrated
in Fig. 6, the main fender portion 86, which is a part of the rear fender 80, and
the engine unit 40 are fastened to each other by a fastener 92B. Thus, the air cleaner
100 and the main fender portion 86 are fixed to each other, and in addition, the air
cleaner 100 and the main fender portion 86 are both fixed to the engine unit 40. Therefore,
even when the rear fender 80 swings, the air cleaner 100 and the main fender portion
86 can be prevented from chattering and position shifting.
[0098] As illustrated in Fig. 9, the leftmost end 142 of the air cleaner 100 (more specifically,
the leftmost end 142 of the second case 140) is positioned to the left of the vehicle
center line L1. The rightmost end 112 of the air cleaner 100 (more specifically, the
rightmost end 112 of the first case 110) is positioned to the right of the vehicle
center line L1. The entire lateral part of a front portion 150 of the rear fender
80 is formed by the air cleaner 100. By forming the entire part of the front portion
150 of the rear fender 80 by the air cleaner 100 in this way, the width of the air
cleaner 100 can be made large. As a result, the air cleaner 100 can be ensured to
have a large capacity. It should be noted that in the present embodiment, the front
portion 150 of the rear fender 80 is the front end face of the air cleaner 100, but
the front portion 150 may be a portion that is more rearward than the front end face.
[0099] A boundary 152 between the main fender portion 86 and the air cleaner 100 is inclined
with respect to the vehicle center line L1, as viewed in plan. The air cleaner 100
is formed so that its front-to-rear length is longer either toward the right or toward
the left, as viewed in plan. In the present embodiment, a portion of the boundary
152 between the main fender portion 86 and the air cleaner 100 (more specifically,
a region on the right of the laterally central part of the air cleaner 100) is inclined
with respect to the vehicle center line L1 as viewed in plan. In other words, the
air cleaner 100 is formed so that its front-to-rear length is longer from the left
toward the right. With such a configuration, the air cleaner 100 can be ensured to
have a large capacity. When the air cleaner 100 has a large capacity, a large amount
of air can be sucked in at one time, so that the engine performance can be improved.
[0100] As illustrated in Fig. 4, the air cleaner 100 is formed so that, as viewed in plan,
its front-to-rear length is longer from one of the left and right sides on which the
footrest 35 is provided toward the other. In the present embodiment, the footrest
35 is provided on the left seat frame 26. The air cleaner 100 is formed so that its
front-to-rear length is longer from the left toward the right. Thus, by making the
front-to-rear length of the air cleaner 100 longer while avoiding the interference
between the air cleaner 100 and the footrest 35, the air cleaner 100 can be ensured
to have a large capacity.
[0101] As illustrated in Fig. 9, in the present embodiment, a recessed portion 88 in which
a portion of the rear cushion unit 95 (see Fig. 5) can be accommodated is formed in
a left portion of the rear fender 80. The middle position between the leftmost end
142 and the rightmost end 112 of the air cleaner 100 (see reference character L4 in
Fig. 9) is biased rightward from the vehicle center line L1. In other words, the middle
position of the air cleaner 100 is biased toward the opposite side to one of the left
and right sides of the vehicle center line L1 in which the recessed portion 88 of
the rear fender 80 is formed.
[0102] As illustrated in Fig. 11, in the present embodiment, the lower end 108 (for example,
the bottom face portion of the first chamber 115) of the air cleaner 100 is positioned
to be lower than the middle position between an upper end 81 A and a lower end 81B
of the rear fender 80. The upper end 81A of the rear fender 80 refers to the vertically
uppermost portion of the main fender portion 86 in the rear fender 80 mounted to the
engine unit 40. Typically, the vertically uppermost portion of the main fender portion
86 and the vertically uppermost portion of the air cleaner 100 are located at substantially
the same height from the ground. The lower end 81B of the rear fender 80 refers to
the vertically lowermost portion of the main fender portion 86 in the rear fender
80 mounted to the engine unit 40. With such a configuration, the position of the seat
13 can be made low, for example, because the air cleaner 100 is disposed at a low
position. Note that the lower end 108 of the air cleaner 100 may be a bottom face
portion of the second chamber 145, depending on the shape of the air cleaner 100.
[0103] The vertical length of the air cleaner 100 varies from the front toward the rear.
As illustrated in Fig. 11, in the present embodiment, the maximum vertical length
of the air cleaner 100 (for example, the maximum vertical length of the first chamber
115) is shorter than the vertical length of the rear fender 80 at the upper end 81A
position (in other words, the vertical length thereof in the vertical cross section
through the position of the upper end 81A). With such a configuration, an additional
spatial margin can be ensured above the air cleaner 100 because the vertical length
of the air cleaner 100 is short. As a result, it becomes possible to dispose other
vehicle components above the air cleaner 100, for example. Alternatively, the position
of the seat 13 may be lowered, for example. Note that the maximum vertical length
of the air cleaner 100 may be the maximum vertical length of the second chamber 145,
depending on the shape of the air cleaner 100.
[0104] The air cleaner 100 forms at least a portion of the upper portion 82 of the rear
fender 80, and therefore, it is not necessary to dispose an air cleaner separately
above the rear fender 80 (for example, over the rear fender 80). Accordingly, there
is a greater additional spatial margin than the case in which an air cleaner is disposed
above the rear fender, so the capacity of the air cleaner 100 can be made larger.
Thereby, the air cleaning performance of the air cleaner 100 can be improved.
[0105] As described above, the air cleaner apparatus 102 according to the present embodiment
has the discharge passage 148, the air inlet unit 120, and the air cleaner case 105,
as illustrated in Fig. 12. The air sucked in from the outside of the air cleaner case
105 passes through the intake passage 130 and flows from the air outlet port 132 into
the first chamber 115. Because the pre-filter element 138 is disposed spaced apart
from the air outlet port 132 so as to be positioned on the axis line of the air outlet
port 132, at least part of the air sucked into the first chamber 115 hits the pre-filter
element 138. As a result, large dust contained in the air strikes the pre-filter element
138 and thereafter falls off. This inhibits the pre-filter element 138 from being
clogged because of the large dust. Therefore, the pre-filter element 138 is unlikely
to be clogged. On the other hand, relatively small dust may be captured by the pre-filter
element 138 when it strikes the pre-filter element 138. For this reason, if the air
is kept sucked from outside, it is possible that the small dust may cause clogging
to some degree in the pre-filter element 138. Nevertheless, the air resistance can
be inhibited from increasing even if some clogging occurs in the pre-filter element
138, because the air sucked from outside can pass through the main filter element
170 without passing through the pre-filter element 138. The air hits the pre-filter
element 138 and thereafter passes through the main filter element 170 disposed between
the first chamber 115 and the second chamber 145. As a result, small dust or the like
that has not been captured by the pre-filter element 138 can be captured by the main
filter element.
[0106] As illustrated in Fig. 12, in the present embodiment, the air cleaner case 105 has
the opposing wall 136 facing the air outlet port 132 and not allowing air to pass
therethrough. The pre-filter element 138 is provided on the opposing wall 136. Thus,
the above-described advantageous effects can be obtained with the simple structure
of providing the pre-filter element 138 on the opposing wall 136.
[0107] In the present embodiment, the opposing wall 136 faces the main filter element 170
in the first chamber 115. Thus, the main filter element 170 and the pre-filter element
138 are disposed at such positions that they oppose each other in the first chamber
115, so most of the air sucked from outside is allowed to hit the pre-filter element
138 first. As a result, the air can be cleaned in good condition.
[0108] In the present embodiment, the pre-filter element 138 is detachably mounted to the
opposing wall 136. This makes it possible to replace the pre-filter element 138 easily
when clogging occurs in the pre-filter element 138 and the cleaning performance of
the pre-filter element 138 degrades. In other words, maintenance of the pre-filter
element 138 can be carried out easily.
[0109] In the present embodiment, the pre-filter element 138 is mounted directly to the
opposing wall 136. Therefore, the need for the complicated structure for mounting
the pre-filter element 138 to the opposing wall 136 is eliminated, and the structure
of the air cleaner apparatus 102 can be simplified.
[0110] In the present embodiment, the air cleaner case 105 has hook members 134 protruding
from the opposing wall 136. The pre-filter element 138 is hooked on the hook members.
For this reason, the pre-filter element 138 can be attached to and detached from the
opposing wall 136 easily. In other words, maintenance of the pre-filter element 138
can be carried out easily.
[0111] In the present embodiment, the pre-filter element 138 is provided on a portion of
the opposing wall 136. Thus, by disposing the pre-filter element 138 on a portion
of the opposing wall 136 that the air sucked from outside can hit easily, cleaning
of air can be carried out with the pre-filter element 138 having a smaller size.
[0112] In the present embodiment, the opposing wall 136 extends in a vertical direction.
Therefore, large dust contained in the air that has been sucked from outside falls
off after it strikes the pre-filter element 138 provided on the wall extending in
a vertical direction. That is, large dust can be removed more effectively.
[0113] In the present embodiment, the air outlet port 132 is disposed between the main filter
element 170 and the pre-filter element 138. Thus, the main filter element 170 and
the pre-filter element 138 are disposed at opposing positions across the air outlet
port 132, so most of the air sucked from outside is allowed to hit the pre-filter
element 138 first. As a result, the air can be cleaned in good condition.
[0114] In the present embodiment, the surface area of the pre-filter element 138 is greater
than the maximum flow passage cross-sectional area of the intake passage 130. Thus,
the pre-filter element 138 has a greater surface area, and therefore, the air blown
off from the air outlet port 132 is allowed to hit the pre-filter element 138 sufficiently.
As a result, the air sucked from outside can be cleaned in good condition by the pre-filter
element 138.
[0115] In the present embodiment, the surface area of the main filter element 170 is greater
than the surface area of the pre-filter element 138. Thus, the air sucked from outside
can be preliminarily cleaned in the pre-filter element 138 by causing large dust to
fall off at the pre-filter element 138 and at the same time small dust to be captured
in the pre-filter element 138, and thereafter, the air can be cleaned sufficiently
in the main filter element 170.
[0116] In the present embodiment, the main filter element 170 comprises a dry-type element.
This makes handling and maintenance of the main filter element easy.
[0117] In the present embodiment, the air outlet port 132 opens in a direction that does
not intersect the main filter element 170. This reduces the air sucked from the outside
of the air cleaner case 105 that directly hits the main filter element 170.
[0118] In the present embodiment, the air outlet port 132 opens in a direction that intersects
the main filter element 138. This enables most of the air that is sucked from the
outside of the air cleaner case 105 to directly hit the pre-filter element 138.
REFERENCE SIGNS LIST
[0119]
1 -- Motorcycle (straddle-type vehicle)
100 -- Air cleaner
102-- Air cleaner apparatus
105 -- Air cleaner case
115 -- First chamber
130 -- Intake passage
132 -- Air outlet port
134 -- Hook member
136 -- Opposing wall
138 -- Pre-filter element (wet-type element)
145 -- Second chamber
148 -- Discharge passage
170 -- Main filter element (dry-type element)