CN101548090B - Air cleaner device for internal combustion engine and internal combustion engine - Google Patents

Abstract

The invention relates to an air cleaner device that has a reduced size achieved by curving an air introduction path, which has a cleaner element with extended service life, and in which air flows uniformly in a clean chamber. The air introduction path (21) having an exit (21o) open to a dust chamber (12) of an air cleaner chamber (11) of an air cleaner (10) has a bent path partitioned by a flow regulation plate (22) into an inside branch path (23) inside the curve and an outside branch path (24) outside the curve. Airflows separately flowing into the dust chamber (12) from the exit (21o) after passing through the inside and outside branch paths (23, 24) are deflected upward and directed toward the cleaner element (F) by a first deflection section (33) and a second deflection section (34) arranged in the dust chamber (12). The second deflection section (34) is located at a position closer in the front-rear direction to the exit (21o) than the first deflection section (33).

Description

Air cleaning device for an internal combustion engine and internal combustion engine

Technical Field

The present invention relates to an air cleaning device for an intake device of an internal combustion engine and the internal combustion engine.

Background

In an air cleaning device for an internal combustion engine, an air cleaner chamber is divided into a dust chamber and a clean chamber, a cleaner element is interposed between the two chambers, an outlet of an air introduction passage opens into the dust chamber, and an inlet of an air discharge passage opens into the clean chamber. It is known for such air cleaning devices to provide means in the dust chamber for allowing air flowing toward the dust chamber to impinge substantially uniformly on the cleaner element (see, for example, patent document 1).

Patent document 1: japanese patent unexamined publication No. JP-A-2000-346687.

Disclosure of Invention

Problems to be solved by the invention

In some cases, in an air cleaning device for an internal combustion engine, an air introduction passage for introducing air taken from the outside of the internal combustion engine into a dust chamber is formed as a curved passage due to the restriction of a space in which the internal combustion engine is disposed or peripheral components disposed around the air cleaning device. However, due to the centrifugal force, the air flowing in the curved passage becomes an air flow having a large flow rate outside the curve. In this state, when the air flowing from the air introduction passage having the curved passage to the dust chamber impinges on the cleaner element, a portion of the cleaner element mainly corresponding to the air from the outside of the curve is more heavily contaminated (e.g., clogged) than other portions, thereby shortening the life of the cleaner element.

Further, when the air flowing from the air introduction passage to the dust chamber is divided into a plurality of flows in the dust chamber, the air flow in the clean chamber is biased when a time lag between times at which the divided air impinges on the cleaner elements, respectively, is large. Thus, the air flow in the air discharge passage is biased. The drift of the air flow in the air discharge passage causes the formation of mixed gas, the reduction of the uniformity of mixing with blowby gas or recirculated exhaust gas generated by the exhaust gas recirculation device, or the reduction of the detection accuracy of the air flow meter when the air discharge passage is provided with an air flow rate meter that detects the air flow rate.

The present invention has been achieved in view of these problems, and an object of the present invention is to miniaturize an air cleaning device by bending an air introduction passage, extend the life of a cleaner element, and improve the uniformity of air flow in a dry chamber in an air cleaning device for an internal combustion engine.

Means for solving the problems

The present invention described in a first aspect is an air cleaning device for an internal combustion engine, comprising:

an air cleaner chamber divided into a dust chamber formed at a lower side and a clean chamber formed at an upper side, between which a cleaner element is interposed in an up-down direction; wherein,

an outlet of an air introduction passage having an air introduction port opens into the dust chamber;

the inlet of the air discharge channel opens into the clean chamber; the air cleaning device is characterized in that,

a chamber wall of the air cleaner chamber including a bottom wall opposed to the cleaner element in an up-down direction and a pair of side walls upstanding from the bottom wall;

the pair of side walls includes a first side wall connected to the air introduction passage and a second side wall opposite to the first side wall in an opposite direction while interposing the cleaner element therebetween;

the air introduction passage has a curved passage divided into a curved inside branch passage and a curved outside branch passage by a partition wall;

setting, by the curved passage, a first path length from the introduction port to the outlet port via the curved inside branch passage to be shorter than a second path length from the introduction port to the outlet port via the curved outside branch passage;

the curved passage is curved toward an upstream side in a direction intersecting the opposing direction as viewed in the up-down direction;

providing first and second deflecting portions in the dust chamber so as to deflect upward an air flow flowing from the outlet to the dust chamber via the curved inner branch passage and the curved outer branch passage, respectively, thereby guiding the air flow toward the cleaner element; and is

The second deflector is closer to the outlet than the first deflector in the opposing direction.

The present invention according to a second aspect is the air cleaning device for an internal combustion engine according to the first aspect, wherein,

the air discharge passage extends from the first side wall toward the second side wall and has the inlet at a location away from the first side wall in the clean chamber; and is

The second deflector is located between the first sidewall and the inlet in the opposing direction.

The present invention according to a third aspect is the air cleaning device for an internal combustion engine according to the first or second aspect, wherein the first and second deflectors include a ridge portion that is provided on the bottom wall and rises upward.

The present invention described in a fourth aspect is the air cleaning device for an internal combustion engine according to any one of the first to third aspects, wherein an interval between the first deflecting portion and the second deflecting portion in the opposing direction is substantially the same as a difference between the first path length and the second path length.

The present invention according to a fifth aspect is the air cleaning device for an internal combustion engine according to the first aspect, wherein,

the air discharge passage has an upstream passage having the inlet and an outlet through which the air flowing in from the inlet flows to the outside of the clean chamber;

said upstream channel is formed by an upstream duct connected to a side wall of said clean chamber in said first side wall and extending in said opposite direction in said clean chamber; and is

The first deflecting portion and the second deflecting portion are located between the inlet and the outlet in the opposing direction as viewed in the up-down direction.

The present invention according to a sixth aspect is the air cleaning device for an internal combustion engine according to the fifth aspect, wherein,

the first deflector is arranged in the vicinity of the inlet in the opposing direction; and is

Wherein the second deflector is arranged in the opposite direction in the vicinity of the outflow opening.

The present invention described in a seventh aspect is an internal combustion engine including:

an air flow meter that detects a flow rate of air flowing in the intake passage; and

the air cleaning device according to any one of the first to sixth aspects, which forms an air passage constituting an intake passage; wherein

The air passage comprises a first air passage arranged downstream of the air flow meter, and a second air passage having an enclosing passage at least partially enclosing a downstream pipe forming the first air passage in a circumferential direction, an outflow opening of the first air passage leading to the second air passage; and is

A blowby gas introduction port through which blowby gas flows toward the intake passage opens into the enclosure passage upstream of the outlet port.

The invention according to an eighth aspect is the internal combustion engine according to the seventh aspect,

wherein the surrounding channel is an annular channel surrounding the entire circumference of the downstream pipe.

The invention according to a ninth aspect is the internal combustion engine according to the seventh or eighth aspect, wherein,

a flow direction of air at the inflow port of the first air passage and a flow direction of air at the outlet of the second air passage are different from each other; and is

The downstream duct is a bent duct bent to guide the flow of air at the outflow port to the outlet of the second air passage, and the first air passage is a bent passage.

The invention according to a tenth aspect is an internal combustion engine according to a ninth aspect,

wherein the blowby gas introduction port is arranged on an upper side with respect to a channel center line of the bent pipe in the surrounding channel and on an inner side of the bend with respect to the channel center line of the bent pipe in the surrounding channel.

The present invention according to an eleventh aspect is the internal combustion engine according to any one of the seventh to tenth aspects,

wherein the air cleaning device has an upstream duct on which the air flow meter is mounted, the downstream duct, and a second downstream duct forming the second air passage; and is

The downstream pipe is a sealing member for sealing a space between the upstream pipe and the second downstream pipe.

Advantages of the invention

According to the invention described in the first aspect, the air introduction passage connected to the first side wall of the pair of side walls which are opposed to each other in the opposing direction with the cleaner element interposed therebetween is curved in a direction intersecting the opposing direction in plan view. Thus, the air cleaning device can be miniaturized in the opposing direction.

In addition, since the partition wall for dividing the curved passage into the curved inside branch passage and the curved outside branch passage is provided, the air flow in the curved passage is regulated without being deflected to the outside of the curve. Thereby, the flow of air flowing from the air introduction passage having the curved passage to the dust chamber is uniformized. Further, the positions of the first and second deflection portions are different from each other in the opposing direction. Thus, the air flow from the branch passage is guided to the cleaner element over a wide range in the opposing direction. Therefore, the air flowing from the air introduction passage having the curved passage (in which the curved inner branch passage and the curved outer branch passage are formed by the partition wall) to the dust chamber can be uniformly impinged on the cleaner element, and the entire cleaner element can be used. Thus, the life of the cleaner element can be extended.

In addition, since the second deflecting portion is closer to the outlet than the first deflecting portion, which corresponds to the second path length being longer than the first path length, a time lag between times when the air flows flowing from the curved inner branch passage and the curved outer branch passage to the dust chamber are deflected by the first and second deflecting portions, respectively, is reduced. Therefore, the time lag between the times at which the air streams impinge on the cleaner elements, respectively, is reduced. Therefore, the deflection of the air flow in the clean chamber and the air discharge passage is suppressed, thereby improving the uniformity of the air flow in the air discharge passage.

According to the invention described in the second aspect, the air deflected by the second deflecting portion flows through the cleaner element and then flows in the clean chamber toward the area between the first side wall and the inlet of the air discharge passage in the opposite direction, thereby flowing toward the inlet. Therefore, the generation of air stagnation in this region of the clean chamber is suppressed, so that the air flow in the clean chamber becomes smooth. As a result, even when the inlet of the air discharge channel is arranged away from the first side wall, the air in the dust chamber can impinge uniformly on the cleaner element.

According to the invention described in the third aspect, the air flow flowing from the branch passage toward the dust chamber and then flowing along the bottom wall in the vicinity of the bottom wall is deflected by the deflecting portion (which is formed by the bulging portion bulging forward from the bottom wall) toward the cleaner element arranged on the upper side. Thus, the air flow between the bottom wall and the cleaner element is effectively guided to the cleaner element by the air flow deflected by the deflecting portion from the vicinity of the bottom wall. As a result, since the deflecting portion for allowing the air flowing from the air introduction passage to uniformly impinge on the cleaner element can be miniaturized, the air flow resistance in the dust chamber is reduced, and the air intake efficiency is improved.

According to the invention described in the fourth aspect, the interval between the first inflection portion and the second inflection portion is substantially the same as the difference between the path length through the curved inside branch passage and the path length through the curved outside branch passage. Thus, the time lag between the times at which the air flows from the curved inner branch passage and the curved outer branch passage toward the dust chamber are deflected by the first and second deflecting portions, respectively, is greatly reduced. Thus, the time lag between the times at which the air streams impinge on the cleaner elements, respectively, is greatly reduced. Therefore, the deflection of the air flow in the clean chamber and the air discharge passage is further suppressed, thereby further improving the uniformity of the air flow in the air discharge passage.

According to the invention described in the fifth aspect, the air deflected by the second deflecting portion flows through the cleaner element and then flows in the cleaning chamber to the area between the inlet and the outlet of the upstream passage, thereby flowing toward the inlet. Therefore, the generation of air stagnation in this region of the clean chamber is suppressed, so that the air flow in the clean chamber becomes smooth. As a result, even when the inlet and the outlet of the upstream passage formed by the upstream duct arranged in the clean chamber are arranged away from each other in the opposing direction, the air in the dust chamber can uniformly impinge on the cleaner element by the second deflecting portion.

According to the invention described in the sixth aspect, the air flowing into the dust chamber from the air introducing passage is deflected upward to be directed to the area between the inlet of the upstream passage and the second side wall in the opposing direction. In addition, the air is deflected upward by the second deflecting portion to be guided to a region between the inlet and the outlet in the opposing direction. As a result, the air in the dust chamber can uniformly impinge on the cleaner element. Further, since interference between the amounts of air deflected by the first and second deflecting portions can be reduced, the effect that the air can uniformly impinge on the cleaner element can be further improved.

According to the invention described in the seventh aspect, the surrounding passage to which the blowby gas introduction port opens is a passage surrounding the downstream pipe. Thus, the surrounding passage is a passage in which the air flow is smaller than that of the first air passage, and the flow rate fluctuation of the blowby gas is reduced in the surrounding passage. Further, since the flow fluctuation of the blowby gas is transmitted from the outflow port to the air in the first air passage via the surrounding passage, the transmission path length when the flow fluctuation is transmitted from the blowby gas introduction port to the air flow meter is longer than the length of the first air passage by the length of the surrounding passage.

As a result, the influence of the flow rate fluctuation of the blowby gas flowing to the intake passage on the detection air flow rate by the air flow meter is reduced, and the detection accuracy of the air flow meter is improved. By surrounding the passage, the transfer path length is made longer without making the length of the first air passage longer, so that the influence of the flow fluctuation of the blowby gas on the air flow meter can be reduced, and the air cleaning device can be miniaturized.

According to the invention as described in the eighth aspect, the surrounding passage is an annular passage that surrounds the entire periphery of the first downstream pipe, so the volume of the surrounding passage is large. Thus, the flow rate fluctuation of the blowby gas in the surrounding passage is further reduced. Therefore, the influence of the flow fluctuation of the blowby gas on the flow detection by the air flow meter is further reduced.

In addition, the blowby gas can be allowed to flow downstream of the outlet over a wide range in the circumferential direction, so the mixing uniformity of the blowby gas and the air flowing in from the first downstream piping can be improved.

According to the invention described in the ninth aspect, even when the flow direction of the air at the inflow port of the first air passage and the flow direction of the air at the outlet of the second air passage are different from each other, the air flowing in the first air passage is smoothly guided to the outlet by the curved duct to flow from the outflow port to the outlet. Thereby suppressing the air flowing from the first air passage from flowing in the second air passage in a turbulent manner and improving the intake efficiency.

According to the invention described in the tenth aspect, the blowby gas introduction port is arranged on the upper side and located inside the bend with respect to the passage center line surrounding the bent pipe in the passage. Thus, the remaining oil remaining in the blowby gas flows toward the outflow port together with the blowby gas while dropping in the surrounding passage, and is mixed with the air flowing from the curved passage. As a result, by effectively utilizing the space formed when the bent duct is used, accumulation of the remaining oil in the lower portion of the surrounding passage is suppressed, and the remaining oil is easily introduced into the second air passage disposed downstream of the outflow port.

The space inside the curve formed inside the curve with respect to the passage center line of the curved duct is narrower than the space outside the curve formed outside the curve with respect to the passage center line. Since the blowby gas introduction port which does not require a large arrangement space is arranged in the curved inside space, a part of the air cleaning device or a different component (such as a peripheral component of the air cleaning device) may be arranged in the curved outside space. In this way, the use of the curved outer space can be maximized. Further, by effectively utilizing the space formed when the bent duct is used, the degree of freedom in arrangement of different components can be increased, so that miniaturization of the air cleaning device or compact arrangement of the air cleaning device and peripheral components can be achieved.

According to the invention described in the eleventh aspect, the downstream pipe also serves as a sealing member that hermetically connects the upstream pipe and the second downstream pipe. As a result, only the upstream pipe, the downstream pipe, and the second downstream pipe 70 are required, and no other sealing member is required. Thus, the number of parts can be reduced, and thus the cost can be reduced.

Drawings

Fig. 1 is a plan view showing a main part of an air cleaning device for an internal combustion engine to which the present invention is applied, and schematically shows the components shown in fig. 4;

fig. 2 is a view seen in the direction of arrow II of fig. 1;

fig. 3 is a view seen in the direction of arrow III of fig. 1;

FIG. 4 is an exploded plan view of the air cleaning device of FIG. 1;

FIG. 5 is a cross-sectional view taken along line V-V of FIGS. 2 and 6;

FIG. 6 is a cross-sectional view taken along line VI-VI of FIGS. 3 and 5;

fig. 7 is a plan view partially in section showing the air cleaning device of fig. 1 with a portion removed; and is

Fig. 8 is a plan view showing a section of a part of a main part of the air cleaning device of fig. 1.

Description of reference numerals

10: air cleaner

11: air cleaner chamber

12: dust chamber

13: clean chamber

14: bottom wall

16, 17: side wall

21: air introduction channel

21 i: introduction port

21 o: an outlet

22: rectifying plate

23, 24: branch channel

33, 34: deflection unit

41: air discharge passage

50: upstream pipeline

51: upstream channel

60: curved pipe

61: curved channel

62: upstream connection part

63: bending part

64: channel part

65: curved channel section

70: downstream pipeline

71: downstream channel

73: peripheral part

74: upstream connection part

76: peripheral channel

80: air flow meter

87: air leakage introducing port

A: air cleaning device

D: opposite direction

F: cleaner element

Detailed Description

Embodiments of the present invention will be described below with reference to fig. 1 to 8.

Referring to fig. 1 to 3, an internal combustion engine E to which the present invention is applied is mounted on a front wheel drive vehicle, and an intake device of the internal combustion engine E has an air cleaning device a as an intake member, the air cleaning device a being provided with an air cleaner 10, a throttle valve device 2, and an intake pipe device 4. The internal combustion engine E and a transmission to which power generated from the internal combustion engine is input constitute a power unit that is disposed in an engine room formed in the front portion of the vehicle body.

The multi-cylinder four-stroke internal combustion engine E has an engine body 1, the engine body 1 having a cylinder block 1a and a cylinder head 1b connected to the cylinder block 1a, and pistons reciprocatably fitted in the cylinder block 1 a. The pressure of combustion gas generated by combustion of the mixed gas in a combustion chamber provided in the engine body 1 drives a piston, which drives and rotates a crankshaft supported by the engine body 1.

The air intake device forms an air intake passage (hereinafter referred to as "intake passage") for introducing combustion air into a combustion chamber provided in the engine body 1, and the air cleaning device a forms an air passage P (see fig. 5, 7, and 8) constituting at least a part of the intake passage.

The air flowing in the intake passage passes through an intake port provided in the cylinder head 1b and is then drawn into the combustion chamber while the intake valve is open, which is driven by the valve train of the internal combustion engine E and synchronized with the engine speed, thereby opening and closing the intake port. Therefore, in the internal combustion engine E, intake pulsation generated by the opening and closing of the intake valve is generated in the intake passage.

With the air cleaning device a, the up-down direction is a direction when an air cleaner chamber 11 described later is divided into a dust chamber 12 formed on the lower side and a clean chamber 13 formed on the upper side with a cleaner element F interposed therebetween in the up-down direction. As an example of the up-down direction, the directions shown in fig. 2 and 5 are set as the up-down direction in the present embodiment. Further, as shown in fig. 1 and 7, directions perpendicular to each other on a horizontal plane (a plane perpendicular to the up-down direction) are set as a front-back direction as a first direction and a left-right direction as a second direction.

Here, when one of the front and rear is set as one direction of the first direction, the other of the front and rear is set as the other direction of the first direction, and when one of the left and right is set as one direction of the second direction, the other of the left and right is set as the other direction of the second direction.

Therefore, when the internal combustion engine E having the air cleaning device a incorporated in the intake device is mounted on a vehicle as a machine, the vertical direction may substantially coincide with the vertical direction of the vehicle, but does not necessarily substantially coincide with the vertical direction of the vehicle.

For example, when the internal combustion engine E is mounted on a vehicle, the air cleaning device a is mounted on the power unit by a plurality of mounting portions (not shown) in a state in which the up-down direction of the air cleaning device a substantially coincides with the up-down direction of the vehicle such that the front-back direction is substantially set as the front-back direction of the vehicle and the left-right direction is substantially set as the left-right direction of the vehicle (the width direction of the vehicle), thereby slightly inclining the air cleaning device forward and downward.

What is described herein includes what is meant by the term "substantially" as opposed to what is meant by the term "substantially".

Referring to fig. 1 to 4, the air cleaning device a has a cleaner element F, a cover B7, and a plurality of passage forming members for forming an air passage P. The plurality of passage forming members include first to fourth members B1 to B4, a duct B5, and a cover B6. These first to fourth components B1 to B4, duct B5 and cover B6 are connected to each other to form an air passage P.

Each of the first to fourth members B1 to B4 and the two covers B6 and B7 is a single member formed of synthetic resin, and the tube B5 is a single member formed of elastomer (here, rubber).

The air cleaning device a has an air cleaner 10, a resonator 90, and an introduction duct 20 and a discharge duct 40 respectively connected to the air cleaner 10. The air cleaner 10 serves as a downstream component disposed downstream of the introduction duct 20 and as an upstream component disposed upstream of the discharge duct 40.

Referring additionally to fig. 5 to 7, the air cleaner 10 has a cleaner element F disposed in the air cleaner chamber 11 to serve as a filtering member for removing dust from air passing through the air cleaner chamber 11, and an air cleaner housing C forming the air cleaner chamber 11. The air cleaner chamber 11 is divided into a dust chamber 12 formed on the lower side as an upstream chamber and a clean chamber 13 formed on the upper side as a downstream chamber by a cleaner element F held in the air cleaner case C, with the cleaner element F interposed therebetween in the up-down direction.

The introduction duct 20 forms an air introduction passage 21 for introducing air taken from the outside of the internal combustion engine E into the dust chamber 12. The discharge duct 40 forms an air discharge passage 41 (see fig. 8) for introducing the clean air in the clean chamber 13, which passes through the cleaner element F after flowing from the air introduction passage 21 to the dust chamber 12, into the throttle valve device 2. Thus, the air passage P is constituted by the air introduction passage 21, the air cleaner chamber 11, and the air discharge passage 41.

Here, the upstream and downstream are with respect to the flow of air flowing from the introduction port 21i of the air introduction passage 21 in the intake passage to the combustion chamber. In addition, the air flow direction in the intake passage is hereinafter referred to as "flow direction".

The resonator 90 is provided with a resonance chamber 93 and a resonance communication passage 94 for communicating the resonance chamber 93 with the air introduction passage 21. The resonator 90 functions as an intake silencer to reduce intake noise or increase torque of the internal combustion engine E in a specific engine speed range.

The air cleaner case C is configured by a plurality of case constituting members, and in the present embodiment, the air cleaner case C is configured such that the first to third cases C1 to C3 as three case constituting members are stacked in order from the lower side. The first case C1 and the second case C2 as the bottom case and the middle case constitute a lower case, and the third case C3 constitutes an upper case.

The cleaner element F is interposed between the holding portions C2a and C3a provided in the second case C2 and the third case C3 to maintain an airtight state. The holding portions C2a and C3a are rectangular frames and the cleaner element F is rectangular when viewed from the up-down direction (hereinafter referred to as "in plan view").

The chamber walls of the air cleaner chamber 11 include a bottom wall 14 formed by the first and second housings C1 and C2, a top wall 15 formed by the third housing C3, and side walls 16 and 17, the side walls 16 and 17 standing upright from the bottom wall 14 and enclosing the air cleaner chamber 11 between the bottom wall 14 and the top wall 15. The bottom wall 14 and the top wall 15 are opposed to the cleaner element F in the up-down direction. The side walls 16 and 17 having the first to third cases C1 to C3 are formed of a pair of side walls 16a, 17 a; 16b, 17b and a pair of side walls 16c, 17 c; 16d, 17d and is rectangular in plan view, side walls 16a, 17 a; 16b, 17b are opposed to each other in the front-rear direction as the opposed direction D, and side walls 16c, 17 c; 16D, 17D are opposed to each other in the left-right direction which is a direction perpendicular to the opposing direction D. The paired side walls 16a, 17 a; 16b, 17b are constituted by first side walls 16a and 17a (also referred to as rear walls) connected to the air introduction passage 21 and the air discharge passage 41, and second side walls 16b and 17b (also referred to as front walls) opposite to the side walls 16a and 17a, between which the cleaner elements F are interposed in the opposing direction D. In addition, the side walls 16 and 17 are constituted by a lower side wall 16 as a side wall of the dust chamber 12 and an upper side wall 17 as a side wall of the clean chamber 13.

Thus, the chamber wall of the dust chamber 12 comprises a bottom wall 14 and four lower side walls 16a to 16d, and the chamber wall of the clean chamber 13 comprises a top wall 15 and four upper side walls 17a to 17 d. The cleaner element F is arranged in the air cleaner case C such that the rectangular peripheral edge portions Fa, Fb, Fc and Fd of the cleaner element F have substantially the same portions as the pair of upper side walls 17a and 17b in the front-rear direction and the pair of upper side walls 17C and 17d in the left-right direction.

The first and second cases C1 and C2 are connected to each other such that the first and second parts B1 and B2 are welded to each other at connecting portions B1a and B2a located at edge portions thereof and serving as connecting means. To facilitate maintenance of the air cleaner 10, including the replacement cleaner element F, the second and third housings C2 and C3 are connected to each other by a clamp (not shown) as a connecting means for removably connecting the housings.

An introduction duct 20 is connected to the lower sidewall 16a so as to communicate the air introduction passage 21 with the dust chamber 12. The air introduction passage 21 has an air introduction port 21i and an outlet port 21o that opens to the dust chamber 12 through the lower side wall 16 a. The introduction duct 20 arranged parallel to the air cleaner 10 in the front-rear direction is a curved duct (see fig. 1 and 7) that extends rearward from the lower side wall 16a or the outlet 21o and is curved leftward from the outlet 21o and the immediately upstream of the lower side wall 16a, thereby miniaturizing the air cleaning device a in the front-rear direction. Therefore, the air introduction passage 21 is also a similar curved passage.

The introduction duct 20 is formed of a first duct part 20a and a second duct part 20b, the first duct part 20a being integrally formed with the first case C1 to be connected thereto, and the second duct part 20b being integrally formed with the second case C2 to be connected thereto. The first casing C1 and the first duct portion 20a are constituted by a first member B1, and the second casing C2 and the second duct portion 20B are constituted by a second member B2. The first and second pipe sections 20a and 20B are connected to each other in such a manner that the connection portions B1a and B2a are welded to each other. The introduction duct 20 has a linear portion 20s and a single curved portion 20c curved in an arc shape in a plan view.

The air introduction passage 21 has a linear passage 21s formed by the linear portion 20s on the upstream side and a single curved passage 21c formed by the curved portion 20c, the linear passage 21s having a substantially linear passage center line, the curved passage 21c being connected downstream of the linear portion 20 s. When the air introducing passage 21 is divided into two, that is, into an upstream passage and a downstream passage, the linear passage 21s extending downward and inclined from the introduction port 21i toward the downstream side is the upstream passage having the introduction port 21i, and the curved passage 21c extending substantially horizontally from the curved start portion toward the downstream side is the downstream passage having the outlet port 21 o.

As shown in fig. 1 and 7, the curved passage 21c is curved toward the upstream side in the direction intersecting the front-rear direction (i.e., toward the left as a direction perpendicular to the opposing direction D herein) in plan view. The linear passage 21s extends leftward from the curved passage 21c toward the upstream side substantially parallel to the left-right direction.

Referring to fig. 2 and 4 to 7, the curved passage 21c is divided into a predetermined number of branch passages, i.e., a curved inner branch passage 23 and a curved outer branch passage 24, which are two branch passages in the left-right direction in the present embodiment, by one or more partition walls formed integrally with the first duct portion 20a, which is one of the duct portions 20a and 20b, and curved along the passage center line of the curved portion 20c, by the rectifying plate 22, which is one partition wall in the present embodiment. A rectifying plate 22 provided in the air introduction passage 21 is arranged downstream of the introduction port 21i, and is arranged in the curved passage 21c from the downstream end portion of the linear passage 21s to the outlet port 21 o. It is preferable that the gap between the flow rectification plate 22 and the duct portion 20b in the up-down direction be 0 or as small as possible from the viewpoint of the flow uniformity of the air in the branch passages 23 and 24.

Here, "curved inner side" and "curved outer side" mean that the curved member or the curved portion is positioned close to the center of curvature of the curve and the curved member or the curved portion is positioned away from the center of curvature of the curve with respect to the reference portion.

Thus, the outlet 21o is divided into an outlet 23o of the curved inner branch passage 23 and an outlet 24o of the curved outer branch passage 24, and these outlets 23o and 24o are positioned the same in the up-down direction and are parallel to each other in the direction intersecting the front-rear direction on the same horizontal plane (i.e., in the left-right direction in plan view here). As a result, the outlet 21o is divided into a predetermined number of outlets, i.e., two outlets 23o and 24o by the rectifying plate 22 here.

The lower portion of the outlet portion 20o of the introduction duct 20, which forms the outlet 21o, is continuous with the bottom wall 14 in a substantially horizontal plane (see fig. 5 and 6). Therefore, the air from the curved inner branch passage 23 and the curved outer branch passage 24 flows into the dust chamber 12 from the outlets 23o and 24o, and then is quickly guided to the bottom wall 14 to flow into the dust chamber 12.

The rectifying plate 22 arranged on the passage center line of the curved passage 21c in plan view suppresses the air flowing in the linear passage 21s from flowing largely to the curved outside branch passage 24 due to the centrifugal force. Thus, the flow rates of the air flowing in the curved inner branch passage 23 and the curved outer branch passage 24 are uniform.

Since the air introduction passage 21 has the curved passage 21c, a first path length from the introduction port 21i to the outlet 23o via the curved inside branch passage 23 is set shorter than a second path length from the introduction port 21i to the outlet 24o via the curved outside branch passage 24. As a result, when the pulsating air flows in the air introduction channel 21, the air flowing in the curved inside branch channel 23 impinges on the outlet 21o from the introduction port 21i for a shorter time than the air flowing in the curved outside branch channel 21 impinges on the outlet 21o, and thus the air flowing in the curved inside branch channel 23 flows toward the dust chamber 12 more rapidly than the air flowing in the curved outside branch channel 24.

Referring to fig. 5 to 7, in the dust chamber 12 to which the air introduction passage 21 opens, the bottom wall 14 is provided with: a lower flat portion 30 continuous with the outlet portion 20 o; an air guide portion 31 projecting upward with respect to the lower flat portion 30 to guide the air flowing from the air introduction passage 21 toward the dust chamber 12 to uniformly impinge on the cleaner element F; and a water collecting space 38 in which water mixed in the air and separated from the air by the cleaner element F is collected 38.

The air guide 31 has a deflection portion 32 and an upper flat portion 36. The deflecting portion 32 deflects the air flow flowing from the curved inner branch passage 23 and the curved outer branch passage 24 toward the dust chamber 12 and then guided to the lower flat portion 30 upward to guide it toward the cleaner element F disposed above the bottom wall 14. The upper flat portion 36 functions as a diffusion suppressing portion for suppressing the air flow just after being deflected by the deflecting portion 32 from being directed downward to be separated from the cleaner element F and diffused therefrom. Both flats 30 and 36 are substantially parallel to a horizontal plane. In fig. 5, the deflected flow of air is schematically shown by the outline arrows.

The deflecting portion 32 formed integrally with the first case C1 constituting the bottom wall 14 is formed of a raised portion in which the outer surface of the bottom wall 14 is a recessed portion. Since the rising portion rises upward from the lower flat portion 30, the rising portion protrudes upward with respect to the lower flat portion 30. The inflections 32 folded in a step shape between the pair of lower side walls 16c and 16d and extending in the left-right direction in a plan view have a predetermined number of inflections. In this embodiment, the deflecting portion 32 has two deflecting portions, i.e., a first deflecting portion 33 and a second deflecting portion 34, the first deflecting portion 33 being for deflecting most of the air flow flowing out from the outlet 23o via the curved inner branch passage 23 toward the cleaner element F, and the second deflecting portion 34 being for deflecting most of the air flow flowing out from the outlet 24o via the curved outer branch passage 24 toward the cleaner element F. The offset portion 32 has a connection portion 35, and the connection portion 35 connects the first offset portion 33 and the second offset portion 34 and constitutes a step portion of the first offset portion 33 and the second offset portion 34 in the front-rear direction.

The air flowing into the dust chamber 12 from the air introduction passage 21 (including the air deflected by the first and second deflecting portions 33 and 34) passes through an opening portion C2b (see fig. 4) provided in the second housing C2, and is then guided to the cleaner element F.

The first and second deflection portions 33 and 34 and the connection portion 35 have substantially the same position in the up-down direction, and the position is substantially the same as the position of approximately 1/2 width of the passage width in the up-down direction of the branch passage 23 or 24 or the air introduction passage 21, that is, substantially the same as the center position of the branch passages 23 and 24. Thus, the positions of the first and second deflection portions 33 and 34 and the connection portion 35 in the up-down direction are substantially the same as the lower half portions of the branch passages 23 and 24. The intervals in the up-down direction between the first and second deflecting portions 33 and 34 and the connecting portion 35 and the cleaner element F are substantially equal.

From the lower flat portion 30 upward toward the cleaner element F, the first and second deflecting portions 33 and 34 have first and second guide surfaces 33a and 34a that curve in a convex manner from the lower side wall 16a toward the lower side wall 16b in the front-rear direction (or in the flow direction of air toward the deflecting portions 33 and 34).

The first guide surface 33a and the outlet 23o serving as the guide surfaces of the deflecting portion 32, and the second guide surface 34a and the outlet 24o serving as the guide surfaces of the deflecting portion 32 are arranged to be opposed to each other in the front-rear direction, respectively. Distances in the front-rear direction from a reference outlet set by setting one of the outlets 23o and 24o as the reference outlet to the first guide face 33a and the second guide face 34a are different from each other. In addition, the distance from the reference outlet to the first guide surface 33a is longer than the distance from the reference outlet to the second guide surface 34 a. Further, the first guide surface 33a is located substantially at the center between the dust chamber 12 and the cleaner element F in the front-rear direction, and has the same position as the inlet 51i described later in the front-rear direction. The second guide surface 34a is located substantially at the center between the outlet 24o and the first guide surface 33a in the front-rear direction. Therefore, the second deflecting portion 34 is arranged closer to the outlet 21o or the reference outlet than the first deflecting portion 33 in the front-rear direction.

The interval between the first inflection portion 33 and the second inflection portion 34 in the front-rear direction is substantially the same as the difference in length of the first and second passages (in this embodiment, the interval may be equal to the difference in length of the curved inside branch passage 23 and the curved outside branch passage 24). For this reason, most of the air of the curved inner branch passage 23 and the curved outer branch passage 24 substantially simultaneously impinges on the cleaner element F by the first and second deflectors 33 and 34, so that the time lag between the times when the air passes through the cleaner element F, respectively, is reduced. Thereby, the deflection of the air flow in the clean chamber 13 and the air discharge channel 41 due to the time lag between the times at which the air flow divided in the dust chamber 12 due to the air introduction channel 21 being divided into the curved inner branch channel 23 and the curved outer branch channel 24 impinges on the cleaner element F, respectively, is suppressed.

When the air flowing into the dust chamber 12 from the curved inner side branch passage 23 has a velocity component toward the curved outer side, the connecting portion 35, which is located substantially at the same position as the downstream end 22a of the rectifying plate 22 in the left-right direction, suppresses the air flow so that the air is not deflected to the curved outer side, and guides the air flow so as to be deflected by the first guide surface 33 a. In this way, the air in the dust chamber 12 can be promoted to uniformly impinge on the cleaner element F.

The flat plate-like upper flat portion 36 formed integrally with the second housing C2 is connected to the top portions of the deflection portions 33 and 34 by welding the connection portions B1a and B2a to each other. The upper flat portion 36 has substantially the same position in the up-down direction as the central portions of the branch passages 23 and 24, and extends forward from the deflector 32 toward the lower side wall 16b in the front-rear direction. In addition, the upper flat portion 36 is provided with a reinforcing rib 37 protruding upward, and the reinforcing rib 37 extends substantially horizontally in the left-right direction at the same position as that of the second deflection portion 34 in the left-right direction. By making the reinforcing rib 37 farther from the outlet 21o than the inlet 51i in the front-rear direction, the air flowing forward directly above the second deflector 34 is deflected to quickly impinge on the cleaner element F in an outlet-opposite side region Rb described below.

The water collecting space 38 has an opening portion C2C (see fig. 4), an opening portion C2C is provided in the second housing C2 between the lower sidewall 16b and the upper flat portion 36, and water in the dust chamber 12 flows to the water collecting space 38 via the opening portion C2C. The water collecting space 38 is formed by the air guide portion 31 and a portion 14a of the bottom wall 14 formed integrally with the first case C1 and continuous with the deflection portion 32. For this reason, on the bottom wall 14, the lower flat portion 30 and the water collecting space 38 are formed by the deflector 32 interposed therebetween in the front-rear direction, and the upper flat portion 36 serves as a top wall of the water collecting space 38. Further, the portion 14a and the lower flat portion 30 are provided with a drain portion 39 having a drain hole. In this way, since the water collecting space 38 is formed by the upper flat portion 36 of the air guide 31, the water collecting space 38 can be formed without complicating the structure of the bottom wall 14.

Referring to fig. 1 to 6 and 8, a discharge duct 40 connects the air cleaner 10 to the throttle device 2. The throttle valve device 2 is disposed downstream of the air cleaning device a, and functions as a downstream air intake part to which air passing through the air cleaning device a flows. The throttle valve device 2 has a throttle valve 2b and a throttle body 2a as a body for forming an air passage 3 in which air flowing from the air cleaning device a flows, the throttle valve 2b being disposed in the air passage 3 for controlling the flow rate of the air. The air discharge passage 41 introduces the air in the clean chamber 3 into the air passage 3. The air flowing via the throttle valve device 2 flows into an air passage 5, which has an intake manifold and is formed by an intake pipe device 4, and then flows toward the combustion chamber via an intake port.

Therefore, an intake passage is formed by the air passage P, the air passage 3, and the air passage 5.

The discharge duct 40 is connected to the upper side wall 17, and the upper side wall 17 is connected to communicate the air discharge channel 41 with the clean chamber 13. The discharge duct 40 has an upstream duct 50 and a downstream duct 42, the upstream duct 50 being connected to the upper side wall 17a on the same side as the lower side wall 16a in the opposed direction D (or the front-rear direction) in the chamber wall of the air cleaner chamber 11, the downstream duct 42 being connected to the upstream duct 50 by an upstream connection portion 62 and to the throttle valve device 2 by a downstream connection portion 75.

The air discharge passage 41 has an upstream passage 51 and a downstream passage 43, the upstream passage 51 being formed by the upstream duct 50 and having an inlet 51i, and the downstream passage 43 being formed by the downstream duct 42 and having an outlet 71 o. An outlet 71o formed by the downstream connecting portion 75 leads to the air passage 3 of the throttle device 2 (see fig. 1). The upstream passage 51 is connected to the upper side wall 17a to communicate with the clean chamber 13, and has a passage center line L2 parallel to the front-rear direction. For this reason, in this embodiment, the direction of the passage center line L2 is the front-rear direction.

The upstream conduit 50 is a venturi conduit having an upstream portion 50c and a downstream connection portion 50d, the upstream portion 50c having an inlet portion 50i which enlarges into a funnel shape and forms an inlet 51i to the clean chamber 13, the downstream connection portion 50d forming an outlet 51o to the downstream channel 61. The outlet 51o allows the air flowing from the inlet 51i to flow to a curved passage 61 described below, the curved passage 61 serving as an air passage on the outside of the clean chamber 13. The downstream connecting portion 50d connected to the downstream duct 42 has a flange portion 50e integrally formed with the upper side wall 17a, and extends rearward from the upper side wall 17a to the outside of the clean chamber 13 in the front-rear direction.

The third casing C3 and the upstream duct 50 are constituted by a third member B3, and the upstream duct 50 is formed integrally with the third casing C3.

Referring to the drawings other than fig. 7, the upstream portion 50c extends forward from the upper side wall 17a toward the upper side wall 17b in the clean chamber 13. The upstream passage 51 has an inlet 51i at a position disposed away from the upper side wall 17a in the front-rear direction in the clean chamber 13. The inlet 51i is located substantially on a plane H perpendicular to the front-rear direction and intersecting the first deflector 33 and opens into the clean chamber 13. For this reason, the upstream duct 50 is connected to the side wall 17a of the clean chamber 13 among the first side walls 16a and 17a, and extends in the front-rear direction in the clean chamber 13.

The plane H is used as a boundary including a passage center line L2 of the upstream passage 51 at the inlet 51i, dividing the air cleaner chamber 11 and the cleaner element F into two parts, i.e., an outlet side region Ra close to the outlet 21o of the air introducing passage 21 and an outlet opposite side region Rb remote from the outlet 21 o.

In the front-rear direction, the guide surface 34a of the second deflecting portion 34 is located substantially at the center between the upper side wall 17a or the outlet 51o and the inlet 51i, or slightly closer to the outlet 21o than the center. Therefore, the guide surface 34a is located substantially at the center in the front-rear direction of the passage portion 51c, or slightly closer to the outlet 21o than the center, the passage portion 51c being formed by the upstream portion 50c of the upstream pipe 50 or the upstream portion 50c in the upstream passage 51.

At least a part of the first deflecting portion 33 and at least a part of the second deflecting portion 34 are located between the inlet 51i and the outlet 51o in the front-rear direction in plan view. Here, the downstream end of the entire guide surface 33a is located at substantially the same position as the inlet 51i in the front-rear direction, and the entire guide surface 33a and the entire guide surface 34a are located between the inlet 51i and the outlet 51o in the front-rear direction. The first deflector 33 is disposed near the inlet 51i in the front-rear direction in plan view, and the second deflector 34 is disposed near the outlet 51o in the front-rear direction in plan view.

The upstream portion 50c is formed by an upper duct portion 50b and a lower duct portion 50a projecting downward in the clean chamber 3, the lower duct portion 50a serving as a partition wall of the clean chamber 13 and the upstream passage 51, and the upper duct portion 50b serving as a part of the ceiling wall 15 and projecting upward from first ceiling walls 15c and 15d described below.

With respect to the first ceiling walls 15c and 15d as a part of the ceiling wall 15 in the outlet-side region Ra where the upstream portion 50c is provided, the interval between the first ceiling wall and the cleaner element F in the up-down direction is smaller than the interval between the second ceiling wall 15b as a part of the ceiling wall 15 in the outlet-side region Rb and the cleaner element F in the up-down direction. The pair of first ceiling walls 15c and 15d, between which the upstream portion 50c is interposed, have substantially the same position in the up-down direction as the passage center line L2 of the upstream passage 51. Compared with the case where the first ceiling walls 15c and 15d are located at the same position in the up-down direction as the second ceiling wall 15b, the first ceiling walls 15c and 15d can deflect the air passing through the cleaner element F (including the air deflected by the second deflecting portion 34) toward the inlet 51i quickly, so that the effect of suppressing the generation of air stagnation between the first ceiling walls 15c and 15d and the cleaner element F can be enhanced.

Referring to fig. 3 to 5 and 8, the upper duct portion 50b is provided with a mounting portion 81, and an air flow meter 80 (see also fig. 1) for detecting the flow rate of air flowing in the intake passage is mounted on the mounting portion 81 near the downstream connecting portion 50d by a screw. A detection portion 80a of the airflow meter 80 is provided in the internal combustion engine E to detect an intake air amount for controlling the amount of fuel and the ignition timing, and is disposed in the upstream passage 51 via a through hole 81a provided in the mounting portion 81.

Referring to fig. 1 to 6 and 8, the downstream duct 42 is formed of a bent duct 60 and a second downstream duct 70, the bent duct 60 serving as a first downstream duct as an inner passage forming member connected to the downstream connection portion 50d, and the second downstream duct 70 serving as an outer passage forming member surrounding at least a portion of the bent duct 60. The downstream passage 43 formed by the bent duct 60 and the downstream duct 70 is an air passage arranged downstream of the air flow meter 80, as is the passage portion 51d formed by the downstream connecting portion 50d in the upstream passage 51. The downstream passage 43 has a curved passage 61 and a second downstream passage 71, the curved passage 61 serving as a first downstream passage formed by the curved duct 60, and the second downstream passage 71 formed by the downstream duct 70 serving as an air chamber into which the outflow port 61o of the curved passage 61 opens. Here, the passage portion 51d and the curved passage 61 are a first air passage disposed downstream of the air flow meter 80, and the downstream passage 71 is a second air passage disposed downstream of the air flow meter 80.

The second downstream duct 70 and the second downstream passage 71 at least partially surround the entirety of the curved duct 60 and the curved passage 61 in the direction of the passage centerline L3 (or the flow direction) of the curved passage 61. In this embodiment, the second downstream duct 70 and the second downstream passage 71 surround most of the curved duct 60 and the curved passage 61 from the outside. Furthermore, the downstream duct 70 and the downstream channel 71 circumferentially surround at least partially the entire circumference of the curved duct 60 and the curved channel 61. In this embodiment, the downstream duct and the downstream passage surround the entire periphery of the curved duct 60 and the curved passage 61, and surround the entirety of the below-described curved portion 63 and the curved passage portion 65.

To this end, the downstream pipe 42 has at least a part of a double pipe structure in the circumferential direction, in which the curved pipe 60 serves as an inner pipe and the downstream pipe 70 serves as an outer pipe in a portion where the downstream pipe 70 surrounds the curved pipe 60. In this embodiment, the downstream pipe 42 has a double pipe structure over the entire circumference thereof.

The curved duct 60 including the duct B5 having rubber elasticity has an upstream connecting portion 62 and a curved portion 63, the upstream connecting portion 62 being fitted to the outer periphery of the downstream connecting portion 50d of the upstream duct 50 and forming a corrugated shape extending in the flow direction, the curved portion 63 being connected downstream of the upstream connecting portion 62. In order to miniaturize the air cleaning device a in the front-rear direction, the curved duct 60 extends rearward from the upper side wall 17a or the outlet 51o and is curved rightward. The upstream connecting portion 62 has a convex portion 62b as a position determining portion that engages with the concave portion 74b of the downstream pipe 70.

The curved passage 61 has a linear passage portion 64 formed by the upstream connecting portion 62 and a curved passage portion 65 formed by the curved portion 63. The passage portion 64 has an inlet port 61i of the curved passage 61, and the curved passage portion 65 has an outlet port 61o of the curved passage 61.

The upstream connecting portion 62 has an upstream side seal portion 67 surrounding the downstream connecting portion 50d and contacting the flange portion 50e in the flow direction, and a downstream side seal portion 68 having seal portions 68a and 68b contacting the upstream connecting portion 74 of the downstream pipe 70 in the flow direction and the radial direction, respectively. Here, for the curved duct 60 and the downstream duct 70, the radial direction is the radial direction of the curved duct 60 with respect to the passage center line L3.

With the air cleaning device a assembled, the upstream connection portion 62 is compressed and shortened in the flow direction by the flange portion 50e and the upstream connection portion 74, and hermetically seals the space between the upstream duct 50 and the downstream duct 70. For this reason, the curved duct 60 having the upstream connecting portion 62 also serves as a sealing member for sealing the space between the upstream duct 50 and the downstream duct 70.

The curved portion 63 and the curved passage portion 65 are curved in plan view and extend rearward from the passage portion 64 and the upstream connecting portion 62 in a direction intersecting the front-rear direction, and the upstream connecting portion 62 has a passage center line L3 that coincides with a passage center line L2 of the upstream passage 51. In this embodiment, the curved portion 63 and the curved passage portion 65 are curved and extend rightward in the left-right direction. The outlet 61o formed by the downstream end portion 63d of the curved portion 63 is opened substantially rightward. Therefore, the air flow direction at the inflow port 61i and the air flow direction at the outlet 71o are different from each other and intersect in a plan view. The air at the outlet 61o flows toward the outlet 71 o.

The downstream duct 70 is formed of a concave-shaped housing 72 and a plate-like cover B6, the housing 72 forming a space for accommodating the bent duct 60 and opening downward. The housing 72 and the cover B6 are connected to each other in such a manner that a connecting portion B4B (see fig. 5) as an edge portion of the open bottom of the housing 72 and a connecting portion B6a (see fig. 1 and 5) as an edge portion of the cover B6 are welded to each other as a connecting means. The cover B6 also serves as a partition wall that divides the downstream passage 71 and the resonance chamber 93.

The downstream pipe 70 has an enclosing portion 73, the enclosing portion 73 having an upstream connecting portion 74 and a downstream connecting portion 75 enclosing the periphery of the bent pipe 60, the downstream connecting portion 75 being arranged downstream of the enclosing portion 73 and connected to the throttle device 2. The upstream connecting portion 74 has a recessed portion 74b, and the recessed portion 74b serves as a positioning portion for setting a relative position with respect to the connected curved duct 60. The upstream connecting portion 74 contacts and is fitted to the outer periphery of the downstream sealing portion 68.

The downstream channel 71 has a surrounding channel 76 and a linear channel 77, the linear channel 77 having an outlet 71o and being located downstream of the surrounding channel 76. The surrounding passage 76 is formed by the surrounding portion 73, and serves as an annular passage that surrounds the periphery of the curved duct 60 from the downstream side sealing portion 68 to the downstream end portion 63d, the downstream side sealing portion 68 being the downstream end portion of the upstream connecting portion 62.

By connecting the upstream connecting portion 74 and the upstream connecting portion 62 to each other in an airtight manner, the enclosing passage 76 formed between the curved pipe 60 and the enclosing portion 73 in the radial direction of the curved pipe 60 is closed at the upstream end portion 76a of the enclosing passage 76. In addition, the surrounding passage 76 is a space formed in the downstream passage 71 upstream of the outflow port 61 o.

As shown in fig. 8, the curved duct 60 and the curved passage 61 are curved in a direction crossing the front-rear direction when reaching the upstream side, in plan view, from the upstream connection portion 62 or the inflow port rearward. Here, the curved passage 60 and the curved passage 61 are curved rightward, which is a direction perpendicular to the front-rear direction. The passage 77 extends linearly rightward from the outflow port 61i of the curved passage 61 toward the downstream side substantially parallel to the left-right direction.

In assembling the air cleaning device a, the lower duct 70 is connected to the first case C1 and the second case C2 integrally joined at the air cleaner 10 by welding the second component B2 to the fourth component B4 at the connections B2B, B4a (the connections B2B, B4a are edge portions of the second component B2 and the fourth component B4, refer to fig. 5). After that, the bent pipe 60 is inserted into the downstream pipe 70 via the upstream connecting portion 74, and then, the downstream connecting portion 50d is inserted into the upstream connecting portion 62 in a state where the upstream connecting portions 62 and 74 are connected to each other. The third case C3 is connected to the second case C2 by a jig in a state where the upstream pipe 50 and the bent pipe 60 press the upstream connection portion 62 in the flow direction.

Referring to fig. 1 to 3, 5, and 8, the internal combustion engine E has blowby gas returning means for returning blowby gas to the intake passage. The return means has a gas-liquid separator for separating oil mixed in blowby gas introduced from a crank chamber formed by the engine body 1, and a return line forming a return passage through which the blowby gas from which the oil is separated is introduced into the intake passage. The return line has a pipe 85 (see fig. 6) for introducing blowby gas from the gas-liquid separator and a sleeve 86 connected to the pipe 85, the sleeve 86 being disposed in the discharge pipe 40 and serving as an introduction portion of the downstream passage 71 that allows the blowby gas to flow toward the air discharge passage 41 at a position downstream of the air flow meter 80. A blowby gas introduction port 87 of the return passage leading to the downstream passage 71 is formed by the sleeve 86.

The grommet 86 is mounted in a state in which a through hole as an opening portion provided in the mounting portion 72a is formed in the mounting portion 72a, the mounting portion 72a being a recessed portion provided in the housing 72. In the upper portion of the surrounding duct 76 (in the vicinity of the uppermost position in this embodiment), the blowby gas introduction port 87 is arranged on the curved inner side of the curved duct 60 or the curved passage portion 65 (in this embodiment, on the curved inner side with respect to the passage center line L3) as viewed in a direction (coinciding with the up-down direction in this embodiment) perpendicular to a plane (the plane including substantially the passage center line L3 of the curved duct 60 or the curved passage portion 65).

For this reason, the blowby gas introduction port 87 opens into the surrounding passage 76 or a space located radially between the curved duct 60 and the surrounding portion 73. Further, in a plan view, the blowby gas introduction port 87 is arranged in a curved inside space as a fan-shaped space which is smaller than a curved outside space as a fan-shaped space formed outside the curve (with the passage center line L3 as a boundary).

In order to alleviate the influence of flow rate fluctuation of the blowby gas flowing from the blowby gas introduction port 87 on the detection accuracy of the air flow meter 80, it is preferable to make the distance from the blowby gas introduction port 87 to the outlet port 61o long, and to position the blowby gas introduction port 87 at the upstream end portion 76a, the upstream end portion 76a including the portion farthest from the outlet port 61 o. In addition, the direction of the through hole constituting the blowby gas introduction port 87 is set such that the flow direction of the blowby gas from the blowby gas introduction port 87 is set to a direction substantially opposite to the flow direction of the air at the outlet 61o (to the left in this embodiment).

Referring to fig. 1 to 4, 6 and 7, a resonator 90 provided so as to partially surround the introduction port 20 is formed by a cover B7 and housings 91 and 92, the housings 91 and 92 having second and fourth parts B2 and B4. The cover B7 has a pair of claws B7a inserted into a pair of mounting portions 92a provided in the case 92, and is attached to the case 92 by screws.

The chamber wall of the resonance chamber 93 is formed by the housings 91 and 92 and the second duct portion 20b, and a communication passage 94 for communicating the resonance chamber 93 with the bent outside branch passage 24 is formed by a passage forming portion 95a formed integrally with the first duct portion 29a and a tubular passage forming portion 95b formed integrally with the second duct portion 20 b.

Next, effects and advantages of the embodiment configured as described above will be described. The flow of air flowing from the outside of the internal combustion engine E to the dust chamber 12 via the air introduction passage 21 by the operation of the internal combustion engine E is guided by the air guide portion 31 and deflected upward. The air then passes the cleaner element F and flows to the clean chamber 13. The air in the clean chamber 13 flows via the air outlet channel 41 to the air channel 3 of the throttle device 2. After the air flow is controlled by the throttle valve 2b, air is sucked into the combustion chamber via an air passage 5 of an intake pipe arrangement 4.

The pair of side walls 16a and 16b of the dust chamber 12 of the air cleaner chamber 11 are formed by a side wall 16a connected to the air introduction passage 21 and a side wall 16b opposite to the side wall 16a, with a cleaner element F interposed between the side wall 16a and the side wall 16b in the front-rear direction as the opposing direction D. The air introducing passage 21 has a curved passage 21c, and the curved passage 21c is divided into a curved inner branch passage 23 and a curved outer branch passage 24 by a rectifying plate 22. By the curved passage 21c, a first path length from the introduction port 21i to the outlet port 21o via the curved inside branch passage 23 is set shorter than a second path length from the introduction port 21i to the outlet port 21o via the curved outside branch passage 24. The curved passage 21c is curved toward the upstream side in the left-right direction intersecting the front-rear direction in plan view, and in the dust chamber 12, a first deflecting portion 33 and a second deflecting portion 34 are provided to deflect the flow of air flowing from the outlet 21o to the dust chamber 12 via the curved inner branch passage 23 and the curved outer branch passage 24 to be guided to the cleaner element F. The second deflector 34 is located closer to the outlet 21o than the first deflector 33 in the front-rear direction. According to these structures, the following effects are obtained.

Since the air introducing passage 21 connected to the side wall 16a is curved in a direction crossing the front-rear direction in a plan view in the pair of side walls 16a and 16b opposed to each other with the cleaner element F interposed therebetween in the front-rear direction, the air cleaning device a can be miniaturized in the front-rear direction.

Further, since the flow of air in the curved passage 21c is adjusted so as not to be deflected to the curved outside by the flow rectification plate 22 (the flow rectification plate 22 divides the curved passage 21c into the curved inside branch passage 23 and the curved outside branch passage 24), the flow of air flowing from the air introduction passage 21 having the curved passage 21c to the dust chamber 12 is uniformized. Since the positions of the first and second deflecting portions 33 and 34 are different from each other in the front-rear direction, the air flows from the branch passages 23 and 24 are guided to the cleaner element F over a wide range in the front-rear direction. Therefore, the air flowing from the air introducing passage 21 having the curved passage 21c (the curved inner branch passage 23 and the curved outer branch passage 24 are formed in the air introducing passage 21 by the rectifying plate 22) to the dust chamber 12 can be uniformly impinged on the cleaner element F, and the entire cleaner element F can be used. Therefore, the life of the cleaner element F can be extended.

In addition, since the second deflecting portion 34 is closer to the outlet 21o than the first deflecting portion 33, which corresponds to the second path length being longer than the first path length, a time lag between times when the air flows flowing from the curved inner branch passage 23 and the curved outer branch passage 24 to the dust chamber 12 are deflected by the first and second deflecting portions 33 and 34, respectively, is reduced. Therefore, the time lag between the times at which the air streams impinge on the cleaner elements F, respectively, is reduced. Therefore, the deflection of the air flow in the clean chamber 13 and the air discharge passage 41 is suppressed, thereby improving the uniformity of the air flow in the air discharge passage 41. As a result, the accuracy of detection of the intake air amount by the air flow meter 80 disposed in the upstream passage 51 of the air discharge passage 41 is improved, and the uniformity of mixing of the blowby gas flowing from the blowby gas introduction port 87 to the downstream passage 71 and the intake air is improved.

In addition, since the interval between the first deflecting portion 33 and the second deflecting portion 34 in the front-rear direction is substantially the same as the difference between the first path length and the second path length, the first deflecting portion 33 and the second deflecting portion 34 are disposed apart from each other by the interval which is the same as the difference between the first path length and the second path length. Thus, the time lag between the times at which the air flows flowing from the curved inner branch passage 23 and the curved outer branch passage 24 toward the dust chamber 12 are deflected by the first and second deflecting portions 33 and 34, respectively, is greatly reduced. Therefore, the time lag between the times at which the air streams impinge on the cleaner elements F, respectively, is greatly reduced. Therefore, the deflection of the air flow in the clean chamber 13 and the air discharge passage 41 including the upstream passage 51 is further suppressed, thereby further improving the uniformity of the air flow in the air discharge passage 41.

In the clean chamber 13, the air discharge passage 41 extends from the side wall 17a toward the side wall 17b, and has an inlet 51i at a position away from the side wall 17a or the peripheral edge portion Fa of the cleaner element F. Further, the second deflecting portion 34 is located between the side wall 17a or the peripheral edge portion Fa and the inlet 51i in the front-rear direction. Thus, the air deflected by the second deflecting portion 34 passes through the cleaner element F, and then flows in the front-rear direction toward the side wall 17a or toward the outlet side area Ra between the peripheral portion Fa and the inlet 51i in the clean chamber 13, thereby flowing toward the inlet 51 i. Therefore, the air stagnation is suppressed from being generated in the outlet side area Ra of the clean chamber 13, so that the air flow in the clean chamber 13 becomes smooth. As a result, even when the inlet 51i of the air discharge passage 41 is disposed away from the first side wall 17a or the peripheral edge portion Fa, the air in the dust chamber 12 can uniformly impinge on the cleaner element F.

Since the deflecting portions 33 and 34 are formed by the rising portions provided on the bottom wall 14 and rising upward, and have the curved guide surfaces 33a and 34a, the air flow flowing from the branch passages 23 and 24 toward the dust chamber 12 and then flowing along the bottom wall 14 in the vicinity of the bottom wall 14 is deflected by the deflecting portions 33 and 34 (which are formed by the rising portions rising forward from the bottom wall 14) toward the cleaner element F disposed on the upper side. Thus, the air flow between the bottom wall 14 and the cleaner element F is efficiently guided to the cleaner element F by the air flow deflected by the deflecting portions 33 and 34 from the vicinity of the bottom wall 14. As a result, since the deflecting portions 33 and 34 for allowing the air flowing from the air introduction passage 21 to uniformly impinge on the cleaner element F can be miniaturized, and the air flow is smoothly deflected due to the curved guide surfaces 33a and 34a of the deflecting portions 33 and 34, the air flow resistance in the dust chamber 12 is reduced, and the air intake efficiency is improved.

The air discharge passage 41 has an upstream passage 51 including an inlet 51i and an outlet 51o for allowing air flowing from the inlet 51i to flow to a curved passage 61 disposed outside the clean chamber 13. The upstream passage 51 is formed by an upstream pipe 50, and the upstream pipe 50 is connected to the side wall 17a among the first side walls 16a and 17a of the clean chamber 13, and extends in the front-rear direction in the clean chamber 13. Further, the first and second deflecting portions 33 and 34 are located between the inlet 51i and the outlet 51o in the front-rear direction as viewed in the up-down direction. Thus, the air deflected by the second deflecting portion 34 passes through the cleaner element F and then flows toward the outlet side area Ra between the outlet 51o and the inlet 51i of the upstream passage 51 in the clean chamber 13, thereby flowing toward the inlet 51 i. Therefore, the generation of air stagnation in the outlet side area Ra is suppressed, so that the air flow in the clean chamber 13 becomes smooth. As a result, even when the inlet 51i and the outlet 51o of the upstream passage 51 formed by the upstream duct 50 arranged in the clean chamber 13 are arranged apart from each other in the front-rear direction, the air in the dust chamber 12 can uniformly impinge on the cleaner element F through the second deflecting portion 34.

With respect to the first and second deflectors 33 and 34 arranged between the inlet 51i and the outlet 51o in the front-rear direction, the first deflector 33 is arranged in the front-rear direction in the vicinity of the inlet 51i, and the second deflector 34 is arranged in the front-rear direction in the vicinity of the outlet 51 o. Thus, the air flowing from the air introduction passage 21 into the dust chamber 12 is deflected upward by the first deflecting portion 33 to be directed to a region between the inlet 51i and the side wall 17b in the front-rear direction (i.e., the outlet-side region Tb), and the air is deflected upward by the second deflecting portion 34 to be directed to a region between the inlet 51i and the outlet 51o in the front-rear direction (i.e., the outlet-side region Ra). As a result, the air in the dust chamber 12 can uniformly impinge on the cleaner element F. Further, since interference between the air flows deflected by the first and second deflecting portions 33 and 34 can be reduced, the effect of making the air uniformly impinge on the cleaner element F can be further improved.

The air passage P formed by the air cleaning device a has a curved passage 61 and a second downstream passage 71, the curved passage 61 serves as a first downstream passage arranged downstream of the air flow meter 80, the second downstream passage 71 has an enclosing passage 76 enclosing a curved duct 60 as a downstream duct forming the curved passage 61, and an outlet 61o of the curved passage 61 opens to the second downstream passage 71. Further, by the blowby gas introduction port 87 opening into the surrounding passage 76 upstream of the outflow port 61o, the surrounding passage 76 to which the blowby gas introduction port 87 opens is a passage surrounding the bent duct 60. Thus, the surrounding passage 76 is a passage in which the air flow is smaller than that of the curved passage 61, and the flow rate fluctuation of the blowby gas is reduced in the surrounding passage 76. Further, since the flow rate fluctuation of the blowby gas is transmitted from the outflow port 61o to the air in the curved passage 61 via the surrounding passage 76, the transmission path length, which is the path length when the flow rate fluctuation is transmitted from the blowby gas introduction port 87 to the air flow meter 80, is longer than the length of the surrounding passage 76 than the length of the curved passage 61. As a result, the influence of the flow rate fluctuation of the blowby gas flowing toward the downstream passage 71 of the air passage P on the air flow rate detection by the air flow meter 80 is reduced, and the detection accuracy of the air flow meter 80 is improved. By surrounding the passage 76, the transfer path length is made longer without making the length of the curved passage 61 longer, the influence of the flow rate fluctuation of the blowby gas on the air flow meter 80 can be reduced, and the air cleaning device a can be miniaturized.

Since the enclosed channel 76 is an annular channel that surrounds the entire circumference of the curved conduit 60, the volume of the enclosed channel 76 is large. Thus, the flow rate fluctuation of the blowby gas in the surrounding passage 76 is further reduced. Therefore, the influence of the flow rate fluctuation of the blowby gas on the detected flow rate of the air flow meter 80 is further reduced. In addition, since the blowby gas is allowed to flow downstream of the outflow port 61o over a wide range in the circumferential direction, the mixing uniformity of the blowby gas and the intake air flowing from the curved duct 60 can be improved.

The flow direction of the air at the inflow port 61i of the curved passage 61 and the flow direction of the air at the outlet 71o of the downstream passage 71 are different from each other, and the curved duct 60 is curved to guide the flow of the air at the outflow port 61o of the curved passage 61 to the outlet 71 o. Thus, even when the flow direction of the air at the inlet port 61i and the flow direction of the air at the outlet port 71o are different from each other, the air flowing in the curved passage 61 is smoothly guided to the outlet port 71o by the curved duct 60 to flow from the outlet port 61o to the outlet port 71o, thereby suppressing the air flowing from the curved passage 61 from flowing in the passage 77 of the downstream passage 71 in a turbulent manner, and improving the intake efficiency.

Since the blowby gas introduction port 87 is arranged on the upper side and located on the inside of the curve with respect to the channel center line L3 of the curved duct 60 in the enclosing channel 76, the blowby gas introduction port 87 opens to the enclosing channel 76 on the upper side closer to the inside of the curve than the channel center line L3. Thus, the remaining oil remaining in the blowby gas flows toward the flow-out port 61o together with the blowby gas while dropping in the surrounding passage 76, and is mixed with the air flowing from the curved passage 61. As a result, by effectively utilizing the space formed when the bent pipe 60 is used, accumulation of the remaining oil in the lower portion surrounding the passage 76 is suppressed, and the remaining oil is easily introduced into the passage 77 disposed downstream of the outlet port 61 o.

In addition, although the curved inside space is a space narrower than the curved outside space, since the blowby gas introduction port 87 which does not require a large arrangement space is arranged in the curved inside space, a part of the air cleaning device a (for example, the cover B7 of the resonator 90) or a different component (such as a peripheral component of the air cleaning device a) may be arranged in the curved outside space. In this way, the use of the curved outer space can be maximized. Further, by effectively utilizing the space formed when the bent duct 60 is used, the degree of freedom in arrangement of other components can be increased, so that miniaturization of the air cleaning device a or compact arrangement of the air cleaning device and peripheral components can be achieved.

The air cleaning device a has an upstream pipe 50 on which an air flow meter 80 is mounted, a bent pipe 60, and a second downstream pipe 70 forming a second downstream passage 71. Since the curved duct 60 is a sealing member for sealing a space between the upstream duct 50 and the second downstream duct 70, the curved duct 60 also serves as a sealing member for hermetically connecting the upstream duct 50 and the second downstream duct 70. As a result, only the upstream pipe 50, the bent pipe 60, and the second downstream pipe 70 are required, and no other sealing member is required. Thus, the number of parts can be reduced, and thus the cost can be reduced.

A modified structure according to an embodiment, in which a part of the structure of the above-described embodiment is modified, will be described below. The air intake component may also be a component constituting the air intake device other than the air cleaning device a, such as the throttle valve device 2 or the intake pipe device 4. The curved passage 21c may be formed such that the curved inside branch passage and the curved outside branch passage are separated by a partition wall with two step-shaped gaps interposed therebetween.

The predetermined number may be three or more. In this case, the curved passage 21c is divided into three or more branch passages by two or more partition walls, and the present invention is applied to two branch passages adjacent to each other.

At least a part of the plurality of deflection portions of the deflection portion may have a shape of a non-bulging portion, and may be provided on a portion other than the bottom wall, for example, a side wall, in the air cleaner.

The air introduction passage may have a downstream linear passage connected downstream of the curved passage, and the curved passage 21c may be divided into a curved inside branch passage and a curved outside branch passage by a partition wall, and the downstream linear passage may be divided into a linear branch passage disposed downstream of the curved inside branch passage and a linear branch passage disposed downstream of the curved outside branch passage.

The guide surfaces 33a and 34a may be constituted by a single inclined surface inclined at an angle, and may be constituted by a composite surface, such as a plurality of curved surfaces having different curvatures, a plurality of inclined surfaces having different inclination angles, or a combination of curved surfaces and inclined surfaces.

The second downstream conduit 70 may be connected to the upstream conduit 50 to enclose the entire curved conduit 60 and a portion of the upstream conduit, such as the downstream connection 50 d. In this case, the portion (e.g., the downstream connection 50d) is a portion of the downstream conduit according to the claims of the present invention.

The second downstream conduit 70 may circumferentially surround a portion of the curved conduit 60, not the entire perimeter thereof, such that the surrounding channel 76 may not be an annular conduit and circumferentially partially surrounds the curved conduit 60.

Blowby gas introduction port 87 may open in the lower portion surrounding passage 76. The internal combustion engine may be mounted on a machine other than a vehicle.

The present application is based on Japanese patent application (P.2007-233566) filed on 9/10/2007 and Japanese patent application (P.2007-233567) filed on 9/10/2007, the contents of which are incorporated herein by reference.

Claims (14)

1. An air cleaning device for an internal combustion engine, the air cleaning device comprising:

an air cleaner chamber divided into a dust chamber formed at a lower side and a clean chamber formed at an upper side, between which a cleaner element is interposed in an up-down direction; wherein:

an outlet of an air introduction passage having an air introduction port opens into the dust chamber;

the inlet of the air discharge channel opens into the clean chamber; the air cleaning device is characterized in that,

a chamber wall of the air cleaner chamber including a bottom wall opposed to the cleaner element in an up-down direction and a pair of side walls upstanding from the bottom wall;

the pair of side walls includes a first side wall connected to the air introduction passage and a second side wall opposite to the first side wall in an opposite direction while interposing the cleaner element therebetween;

the air introduction passage has a curved passage divided into a curved inside branch passage and a curved outside branch passage by a partition wall;

setting, by the curved passage, a first path length from the introduction port to the outlet port via the curved inside branch passage to be shorter than a second path length from the introduction port to the outlet port via the curved outside branch passage;

the curved passage is curved toward an upstream side in a direction intersecting the opposing direction as viewed in the up-down direction;

providing first and second deflecting portions in the dust chamber so as to deflect upward an air flow flowing from the outlet to the dust chamber via the curved inner branch passage and the curved outer branch passage, respectively, thereby guiding the air flow toward the cleaner element; and is

The second deflector is closer to the outlet than the first deflector in the opposing direction.

2. The air cleaning device for an internal combustion engine according to claim 1,

the air discharge passage extends from the first side wall toward the second side wall and has the inlet at a location away from the first side wall in the clean chamber; and is

The second deflector is located between the first sidewall and the inlet in the opposing direction.

3. The air cleaning device for an internal combustion engine according to claim 1 or 2,

the first and second deflectors include a ridge portion provided on the bottom wall and rising upward.

4. The air cleaning device for an internal combustion engine according to claim 1 or 2,

an interval between the first deflecting portion and the second deflecting portion in the opposing direction is substantially the same as a difference between the first path length and the second path length.

5. The air cleaning device for an internal combustion engine according to claim 1,

the air discharge passage has an upstream passage having the inlet and an outlet through which the air flowing in from the inlet flows to the outside of the clean chamber;

said upstream channel is formed by an upstream duct connected to a side wall of said clean chamber in said first side wall and extending in said opposite direction in said clean chamber; and is

The first deflecting portion and the second deflecting portion are located between the inlet and the outlet in the opposing direction as viewed in the up-down direction.

6. The air cleaning device for an internal combustion engine according to claim 5,

the first deflector is arranged in the vicinity of the inlet in the opposing direction; and is

Wherein the second deflector is arranged in the opposite direction in the vicinity of the outflow opening.

7. An internal combustion engine, comprising:

an air flow meter that detects a flow rate of air flowing in the intake passage; and

the air cleaning device according to claim 1, which forms an air passage constituting an intake passage; wherein

The air passage comprises a first air passage arranged downstream of the air flow meter, and a second air passage having an enclosing passage at least partially enclosing a downstream pipe forming the first air passage in a circumferential direction, an outflow opening of the first air passage leading to the second air passage; and is

A blowby gas introduction port through which blowby gas flows toward the intake passage opens into the enclosure passage upstream of the outlet port.

8. The internal combustion engine according to claim 7,

wherein the surrounding channel is an annular channel surrounding the entire circumference of the downstream pipe.

9. An internal combustion engine according to claim 7 or 8, wherein

A flow direction of air at the inflow port of the first air passage and a flow direction of air at the outlet of the second air passage are different from each other; and is

The downstream duct is a bent duct bent to guide the flow of air at the outflow port to the outlet of the second air passage, and the first air passage is a bent passage.

10. The internal combustion engine according to claim 9,

wherein the blowby gas introduction port is arranged on an upper side with respect to a channel center line of the bent pipe in the surrounding channel and on an inner side of the bend with respect to the channel center line of the bent pipe in the surrounding channel.

11. An internal combustion engine according to claim 7 or 8, wherein

The air cleaning device has an upstream duct on which the air flow meter is mounted, the downstream duct, and a second downstream duct forming the second air passage; and is

The downstream pipe is a sealing member for sealing a space between the upstream pipe and the second downstream pipe.

12. The air cleaning device for an internal combustion engine according to claim 3,

an interval between the first deflecting portion and the second deflecting portion in the opposing direction is substantially the same as a difference between the first path length and the second path length.

13. The internal combustion engine of claim 9, wherein

The air cleaning device has an upstream duct on which the air flow meter is mounted, the downstream duct, and a second downstream duct forming the second air passage; and is

The downstream pipe is a sealing member for sealing a space between the upstream pipe and the second downstream pipe.

14. The internal combustion engine of claim 10, wherein

The air cleaning device has an upstream duct on which the air flow meter is mounted, the downstream duct, and a second downstream duct forming the second air passage; and is

The downstream pipe is a sealing member for sealing a space between the upstream pipe and the second downstream pipe.

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