JP5368189B2 - Air intake duct - Google Patents

Description

  The present invention relates to an intake duct disposed in an intake portion of an automobile engine.

  In recent years, there has been an increasing demand for noise reduction for automobiles, and there is a demand for measures for reducing intake noise generated from the intake portion of an engine. An intake duct is disposed in the intake portion of the engine, and intake noise is easily radiated from the air inlet of the intake duct. Therefore, conventionally, in order to reduce the intake noise, a so-called “resonance silencer” called a resonator or a side branch is installed to reduce the intake noise.

  However, in the engine room, the number of engine accessories and electronic devices for reducing exhaust gas is increasing, and the space available in the engine room tends to be narrowed. It may be difficult to arrange the vessel. Therefore, as in Patent Document 1 and Patent Document 2, an opening is provided in the middle of the duct body, and the opening is covered with a sheet-like member made of a flexible porous material. An intake duct that reduces the generated air column resonance and reduces the intake sound due to the air column resonance has been put into practical use. 11 to 13 schematically show the configuration of the intake duct disclosed in Patent Document 1 and Patent Document 2. FIG. That is, the intake duct D1 is configured by mounting a sheet-like member S1 that covers the opening 12 on the duct body 10 in which the opening 12 is formed at a required position in the air flow direction.

JP-A-10-281027 JP 2000-282985 A

  The sheet-like member S1 is formed of a porous material such as a thin film having a large number of holes or a nonwoven fabric and has flexibility. For this reason, the sheet-like member S1 is deformed into a concave shape inwardly of the opening 12 by being pushed by the atmosphere at the time of negative pressure in the duct body 10 due to a pressure change in the duct body 10 due to intake air pulsation of the engine (FIG. 14 (a)), when the pressure in the duct body 10 is positive, it deforms outwardly (FIG. 14 (b)). Here, when the sheet-like member S1 is deformed into a recessed shape into the opening 12, the sheet-like member S1 comes into contact with the opening edge 14 of the opening 12, so that the opening edge 14 is particularly angular. In this case, the sheet-like member S1 is worn. In addition, when the wear progresses, the sheet-like member S1 is damaged, and there is a problem that the intake sound leaks to the outside through the opening 12.

  On the other hand, when the sheet-like member S1 bulges outwardly, the sheet-like member S1 is loosened, and the air in the duct body 10 is between the outer surface of the duct body 10 and the sheet-like member S1. Leaks, and there is a problem that the intake sound leaks to the outside through the gap C formed at this time. In particular, in the case of the duct body 10 having an uneven surface, the pressing of the sheet-like member S1 tends to be small at the recessed portion, and a gap C can be formed even by slight deformation of the sheet-like member S1, and the intake sound Sound leaks. If the opening edge 14 is rounded, it is possible to suppress the wear of the sheet-like member S1, but preventing the formation of the gap C still cannot be solved.

  Therefore, an object of the present invention is to provide an intake duct that prevents wear of a sheet-like member and sound leakage of intake sound due to a pressure change in the duct body.

In order to solve the above-mentioned problems and achieve the intended purpose, the invention according to claim 1 of the present application provides:
A cylindrical duct main body having an opening, and a sheet-like member attached to the duct main body so as to cover the opening and having air permeability are disposed in an intake portion of an engine mounted on an automobile. In the intake duct,
On the outer surface of the duct body, a plurality of the openings are provided side by side in the circumferential direction of the duct body , and protrusions formed so as to surround each opening are provided,
The sheet-like member is attached to the duct body under tension so as to come into contact with the tip of each projection.

Therefore, according to the first aspect of the invention, since the sheet-like member is in contact with the tip of each protrusion in a tensioned state, the sheet-like member is separated from the opening edge of each opening. The opening can be covered appropriately . Therefore, at the time of negative pressure in the duct body, even if the portion facing the opening of the sheet-like member is deformed in a concave manner toward the opening, the sheet-like member contacts the opening end of the opening. Can be avoided, and sound leakage from the opening due to wear and breakage of the sheet-like member can be prevented. In addition, when the pressure inside the duct body is positive, even if the portion facing the opening of the sheet-like member bulges and deforms to the opposite side of the opening, the sheet-like member is in contact with the tip of the protrusion. It is possible to prevent sound leakage of the intake sound from the opening.

The invention described in claim 2
The tip of each projection is formed so as to extend continuously in the circumferential direction of the duct body according to the outer surface shape of the duct body,
The gist is that the sheet-like member deforms along the tip of each projection and contacts the tip evenly without a gap.
Therefore, according to the second aspect of the present invention, when the sheet-like member is attached to the outer surface of the duct body with tension, the tip of each protrusion and the sheet-like member are uniformly contacted with no gaps, It is possible to appropriately prevent sound leakage from the opening.

The invention according to claim 3
The gist of the sheet-like member is that only both end portions in the circumferential direction of the duct main body are fixed to the duct main body in a mounted state on the duct main body.
Therefore, according to the invention of claim 3 , since the fixing portion of the sheet-like member with respect to the duct main body is minimized, even if the duct main body is thermally contracted or vibrated, the sheet-like member is pulled or stretched. And the occurrence of tearing of the sheet-like member can be prevented.

The invention according to claim 4
The duct body includes a first locking portion,
The sheet-like member includes second locking portions at both ends in the circumferential direction of the duct body,
The gist of the invention is that the sheet-like member is wound around and fixed to the duct main body in a tensioned state in the circumferential direction by the hooking structure of the first locking portion and the second locking portion by a hole and a claw. .
Therefore, according to the invention which concerns on Claim 4 , the contact state with each projection was hold | maintained by hooking the 1st latching | locking part of a duct main body, and the 2nd latching | locking part of a sheet-like member. The sheet-like member can be wound and fixed around the duct main body in a state, and the sheet-like member does not come off from the duct main body during use.

The invention described in claim 5
The sheet-like member includes a first locking portion at one end in the circumferential direction of the duct body, and a second locking portion at the other end.
The sheet-like member is wound and fixed around the entire circumference of the duct body in a state where tension is applied in the circumferential direction by the hooking structure using the holes and claws of the first locking portion and the second locking portion. And
Therefore, according to the fifth aspect of the present invention, the sheet-like member is kept in contact with each protrusion while the sheet-like member is kept in contact with each projection by hooking the first locking portion and the second locking portion of the sheet-like member. The sheet-like member can be wound and fixed around the main body, and the sheet-like member does not come off from the duct main body during use.

The invention described in claim 6
The first locking portion and the second locking portion are provided apart from each other in the air flow direction of the duct body,
A first locking portion positioned at both ends in at least the air flow direction in each first locking portion, and a second locking portion positioned at both ends in at least the air flow direction in each second locking portion, The gist is to be provided at a position deviated from the protrusion in the air flow direction.
Therefore, according to the invention which concerns on Claim 6 , a tension | tensile_strength becomes especially applied to the part which covers protrusion of a sheet-like member by hooking a 1st latching | locking part and a 2nd latching | locking part, and this sheet-like The member properly contacts the protrusion.

The invention described in claim 7
The gist is that the sheet-like member is formed of a porous material.
Therefore, according to the invention which concerns on Claim 7 , the air column resonance which generate | occur | produces in a duct main body can be reduced suitably.

  According to the intake duct according to the present invention, even if the sheet-like member covering the opening is deformed due to a pressure change in the duct body, wear of the sheet-like member and sound leakage of intake sound can be prevented.

It is a fragmentary perspective view which shows the part which mounted | wore with the sheet-like member in the intake duct of an Example. (a) is sectional drawing of the 2nd duct half body, (b) is the II-II sectional view taken on the line of FIG. It is the III-III sectional view taken on the line of FIG. It is the disassembled perspective view which showed the intake duct of the Example in the state before the assembly of a duct main body, and the mounting | wearing of a sheet-like member. It is explanatory sectional drawing which shows the dimensional relationship of the cyclic | annular processus | protrusion formed so that the opening part of a duct main body might be enclosed, and a sheet-like member. (a) is an explanatory cross-sectional view showing a state in which a portion facing the opening of the sheet-like member is deformed in a concave manner toward the opening due to the negative pressure inside the duct body, (b) These are explanatory sectional views showing a state in which a portion facing the opening of the sheet-like member bulges and deforms to the opposite side of the opening due to the positive pressure inside the duct body. It is a figure which shows the experimental result which measured the sound leak amount for every form example in the intake duct of an Example. It is a graph which shows the measurement result of the radiated sound and transmitted sound in the intake duct of an Example, (a) shows the radiated sound characteristic from a duct front-end | tip, (b) has shown the transmitted sound characteristic from an opening part. . (a) is sectional drawing which shows the part which attaches a sheet-like member to the intake duct of a modification, (b) is sectional drawing which shows the state which attached the sheet-like member to the intake duct of a modification. It is explanatory sectional drawing which shows the extension direction of the latching claw part provided in the 2nd duct half body which makes a U-shaped cross-sectional shape. It is a fragmentary perspective view which shows the part which mounted | wore with the sheet-like member in the conventional intake duct. It is a fragmentary perspective view which shows the conventional intake duct in the state before mounting | wearing a sheet-like member with a duct main body. It is the XX sectional view taken on the line of FIG. (a) is an explanatory cross-sectional view showing a state in which a portion facing the opening of the sheet-like member is deformed in a concave manner toward the opening due to the negative pressure inside the duct body, (b) This is because when the pressure inside the duct body is positive, the portion facing the opening of the sheet-like member bulges and deforms to the opposite side of the opening, forming a gap and causing sound leakage. It is explanatory sectional drawing shown.

  Next, an intake duct according to the present invention will be described below with reference to the accompanying drawings by way of preferred embodiments. In the embodiment, as shown in FIG. 1, the air flow direction in the intake duct D is the “longitudinal direction” of the duct, and the first duct half 30 and the second duct half which will be described later in the radial direction intersecting the air flow direction. The assembly direction with 40 is referred to as the “short direction” of the duct, and the direction around the axis in the longitudinal direction is referred to as the “circumferential direction” of the duct. In the embodiment, a cylindrical intake duct whose cross-sectional shape in the short direction is a perfect circle is illustrated, but the shape of the intake duct is not limited to this.

  FIG. 1 is a partial perspective view showing a main part of an intake duct D of the embodiment, and FIG. 2 shows the intake duct D of FIG. 1 in a state where the duct body 10 is disassembled and the sheet-like member S1 is separated. It is a fragmentary perspective view. The intake duct D according to the embodiment includes a cylindrical duct body 20 having openings 22 and a sheet-like member S that is mounted on the duct body 20 so as to cover the openings 22. The duct body 20 includes a semi-circular first duct half 30 whose semi-circular cross-sectional shape forms a semicircle, and a semi-cylindrical second duct half 40 whose semi-circular cross-sectional shape forms a semi-circle. Are combined.

  The first duct half 30 is a molded member that is made of polypropylene (PP) or high-density polyethylene (HDPE) or the like and is injection-molded or blow-molded. As shown in FIG. 4, in the first duct half 30, the end portions 32 and 32 that are separated in the direction orthogonal to the short direction and extend in parallel in the longitudinal direction are provided with the second duct half. Grooves 34 and 34 into which the respective edge portions 42 and 42 of 40 are fitted are formed. Further, in each end edge portion 32, 32, a penetration hole 36 into which a locking claw portion (first locking portion) 44, 44 protruding from each end edge portion 42, 42 of the second duct half body 40 enters. , 36 are formed. Furthermore, a concave portion 38 that avoids interference with the sheet-like member S attached to the second duct half body 40 is formed at each of the edge portions 32 and 32.

  The second duct half body 40 is a molded member made of polypropylene (PP) or high-density polyethylene (HDPE) or the like and made by injection molding or blow molding. As shown in FIGS. 2B and 4, in the second duct half body 40, end edges 42, 42 extending in parallel in the longitudinal direction and spaced apart in the direction perpendicular to the lateral direction are It fits into the grooves 34, 34 of one duct half 30. Further, in the longitudinal direction of the second duct half body 40, a plurality of (six in the embodiment) opening portions 22 are opened at predetermined intervals in the circumferential direction in a portion where air column resonance of a predetermined frequency occurs. Yes. Therefore, the inside of the duct main body 20 communicates with the outside via each opening 22. Each opening 22 has an opening size based on an opening area effective for reducing air column resonance.

  An annular protrusion (hereinafter referred to as “annular protrusion”) 26 surrounding each opening 22 is formed on the outer peripheral surface of the second duct half 40 so as to protrude from the outer surface of the duct body 20. As shown in FIG. 5, the tip end portion 26 </ b> A of each annular protrusion 26 is formed in a substantially semicircular shape and is not angular. Further, the projecting height H of the annular protrusion 26 is such that the front end portion 26A of the annular protrusion 26 is uniformly in contact with the outer surface of the sheet-like member S attached with tension applied to the duct body 20. It is set on the assumption. That is, as shown in FIG. 2A, each annular protrusion 26 of the embodiment has a substantially constant projection height H from the outer surface of the duct body 20, and the distal end portion 26 </ b> A according to the outer surface shape of the duct body 20. Is formed in a round shape. In other words, the tip portions 26A of the annular protrusions 26 arranged in the circumferential direction of the duct body 20 are formed so as to continuously extend in the circumferential direction of the duct body 20 in accordance with the curvature of the outer surface of the duct body 20. The sheet-like member S is easy to follow. The protrusion height H is preferably T / 2 ≦ H ≦ 3T, where T is the thickness of the sheet-like member S. However, when the outer surface shape of the duct half 40 is not circular, the protrusion height H may be different for each annular protrusion 26.

  Moreover, the protrusion width N of the annular protrusion 26 is set to 1 to 3 mm as shown in FIG. That is, when the protrusion width N is smaller than 1 mm, the shape of the annular protrusion 26 becomes an edge shape, and the annular protrusion 26 may trigger the tearing of the sheet-like member S. When the protrusion width N is larger than 3 mm, the width V of the annular protrusion 26 needs to be increased, so that the width of the sheet-like member S needs to be increased. Arise.

As shown in FIG. 5, the distance G between the opening end 24 of the opening 22 and the inner edge (opening side edge) of the annular protrusion 26 is equal to or less than the protrusion height H of the annular protrusion 26 (0 ≦ G ≦ H). Is desirable. That is, by making the distance G smaller than the protrusion height H, when the portion facing the opening 22 of the sheet-like member S is deformed in a concave manner toward the opening 22 (FIG. 6A), This is because the sheet-like member S can be prevented from contacting the opening end 24 of the opening 22. In addition, as shown in FIG. 3, the duct main body 20 and the sheet-like member S are formed by forming the annular protrusion 26 so that the opening end 24 of the opening 22 and the opening side edge of the annular protrusion 26 are separated from each other. A space wider than the opening 22 (having a larger diameter) can be formed between them. Further, when the second duct half 40 is formed by injection molding, the opening 22 and the annular protrusion 26 can be simultaneously formed at the time of forming the second duct half 40, so the distance G is set to zero. Is possible.

  As shown in FIG. 4, the sheet-like member S is formed in the shape of an elongated rectangular strip from a breathable thin film or porous material. The length L of the sheet-like member S is longer than the entire circumferential length of the second duct half 40, and the width W of the sheet-like member S is the width of each annular protrusion 26 with the largest width in the air flow direction. The width V is 1.5 to 3 times. The porous material has a three-dimensional ventilation space, such as a nonwoven fabric, a urethane foam, a resin foam, a rubber foam, and the like, and the thin film is a two-dimensional many in the direction covering the opening 22. For example, rubber, elastomer, metal net or resin net having through holes.

  The sheet-like member S is configured to be fitted along the outer peripheral surface of the second duct half body 40 in a tensioned state and to lock both end portions in the length direction to the second duct half body 40. ing. That is, as shown in FIGS. 2 (b) and 4, each end edge portion 42, 42 in the longitudinal direction of the second duct half body 40 has two claw-like shapes with a required interval in the longitudinal direction. The locking claw portions (first locking portions) 44, 44 project from the end edge portions 42, 42 in the short direction. On the other hand, at both ends in the length direction of the sheet-like member S, two hole-like locking holes (second locking portions) 50, 50 are provided at predetermined intervals in the width direction. It is formed penetrating in the thickness direction of S. Therefore, the sheet-like member S is fixed to the end edge portion of the second duct half body 40 only by the hooking structure for locking the respective locking hole portions 50 to the corresponding locking claw portions 44. Then, the sheet-like member S is wound in the circumferential direction around the second duct half body 40 in a tensioned state, and comes into contact with the distal end portion 26 </ b> A of each annular protrusion 26 to cover each opening 22.

In addition, as shown to Fig.2 (a), the latching claw parts 44 and 44 formed in the both-ends edge parts 42 and 42 are in the virtual circle which passes through 3 points | pieces of point P1, point P2, and point P3 in point P1. than a tangent of the virtual circle in the tangential and the point P2 of the virtual circle, and has the form so as to extend toward the radially inner side of the duct body 20. Here, the point P1 and the point P2 are the end portions 26A of the annular protrusions 26 and 26 that are located on the outermost side (adjacent to the locking claws 44 and 44) in the circumferential direction of the duct body 20. Further, the point P3 is an annular protrusion 26 that is located at an approximately equal distance from both the point P1 and the point P2 between the point P1 and the point P2 or the highest part from the outer periphery of the duct body 20 of the annular protrusion 26. The diameter of the imaginary circle is a part that increases. Therefore, by forming the respective locking claws 44, 44 on the inner side of the tangent line of the virtual circle, as shown in FIG. 2B, the locking holes 50, 50 are formed in the respective locking claws 44, 44. The sheet-like member S attached to the duct main body 20 with being locked is deformed so that both end portions in the circumferential direction are close to each other in the direction intersecting the short-side direction, and adjacent to the respective locking claw portions 44, 44. All the annular projections 26 including the annular projections 26 and 26 to be contacted with no gap.

  Further, as shown in FIG. 4, the locking width M in the longitudinal direction of the locking claws 44, 44 is greater than the width V of the annular projection 26 in which the width in the longitudinal direction is the maximum in each annular projection 26. Largely set. Both the locking claws 44 and 44 are formed so as to be positioned away from the annular protrusion 26 in the longitudinal direction of the duct body 20. That is, each locking claw portion 44 is provided outside the annular protrusion 26. Accordingly, in the sheet-like member S, both side portions sandwiching the annular protrusions 26 in the longitudinal direction come into contact with the outer peripheral surface of the second duct half body 40 in a straight line particularly under tension, and the annular protrusions 26 The pressing of the sheet-like member S against the tip portion 26A is strengthened.

  In the air intake duct D of the embodiment configured as described above, prior to the assembly of the duct body 20, first, the locking claw portions 44 are inserted into the locking holes 50 to apply tension to the sheet-like member S. In this state, the second duct half 40 is mounted. Next, the second duct half 40 and the first duct half 30 fitted with the sheet-like member S are joined to the end edges 42, 42/32, 32 to form a cylindrical duct body 20. Thereby, since each latching claw part 44 penetrates into the penetration holes 36 and 36 provided in the edge parts 32 and 32 of the 1st duct half body 30, the both ends of the sheet-like member S are each latching claw part 44. This prevents the sheet-like member S from being peeled off from the second duct half 40. That is, the sheet-like member S is fixed to the duct body 20 only at both ends in the length direction. The sheet-like member S is in contact with each annular protrusion 26 and is not bonded and fixed. Therefore, the sheet-like member S can move with respect to each annular protrusion 26, and for example, the sheet-like member S can be prevented from being pulled or stretched due to thermal contraction or vibration of the duct body 20.

  The intake duct D according to the embodiment is mounted on an intake portion of an engine (not shown) and used for the implementation, and the pressure inside the duct body 20 changes to positive pressure and negative pressure due to intake air pulsation of the engine. The sheet-like member S is pushed by the atmosphere at the time of negative pressure in the duct body 20 and deformed into a concave shape toward each opening 22 side (inner side) (FIG. 6A). However, since the sheet-like member S is in contact with the tip end portion 26 </ b> A of the annular protrusion 26, it does not contact the opening end 24 of the opening portion 22. In addition, since the tip end portion 26A of the annular protrusion 26 is not angular, even if the sheet-like member S is in contact with the annular protrusion 26, the sheet-like protrusion S is not worn. Therefore, it is possible to prevent occurrence of sound leakage of the intake sound through the opening 22 due to breakage caused by wear of the sheet-like member S.

  On the other hand, the sheet-like member S bulges and deforms to the side opposite to the opening 22 (outside) at the time of positive pressure in the duct body 20 (FIG. 6B). However, since the sheet-like member S is in contact with the entire circumference of the tip portion 26A of each annular protrusion 26 in a tensioned state, the sheet-like member S is not separated from the tip portion 26A of the annular protrusion 26. Accordingly, it is possible to prevent the occurrence of sound leakage of the intake sound through the opening 22 from between the sheet-like member S and the annular protrusion 26.

Therefore, according to the intake duct D of the embodiment, the following operational effects can be obtained.
(1) Since the sheet-like member S is in contact with the tip portion 26A of each annular protrusion 26 in a tensioned state, the sheet-like member S is separated from the opening edge 24 of the opening 22 and the opening 22 It comes to coat. Therefore, at the time of negative pressure in the duct main body 20, even if a portion facing the opening 22 of the sheet-like member S is deformed in a concave manner toward the opening 22 (inner side), the sheet-like member S remains at the open end. 24 can be avoided, and sound leakage from the opening 22 due to wear and breakage of the sheet-like member S can be prevented. Further, when the pressure in the duct body 20 is positive, even if the portion of the sheet-like member S that faces the opening 22 is bulged and deformed to the side opposite to the opening 22 (outside), the sheet-like member S It can be held in contact with the tip 26A of the annular protrusion 26, and sound leakage of the intake sound from the opening 22 can be prevented.
(2) When the sheet-like member S is bonded to each annular protrusion 26, the sheet-like member S may be torn or torn unless the sheet-like member S can follow the deformation of the duct body 20. However, in the intake duct D of the embodiment, only both end portions in the length direction of the sheet-like member S are fixed to the duct body 20. Therefore, since the intake duct D of the embodiment minimizes the fixing portion of the sheet-like member S with respect to the duct main body 20, even if the duct main body 20 thermally contracts or vibrates, the sheet-like member S generally follows. For this reason (because the entire sheet-like member S absorbs stress), the sheet-like member S can be prevented from being torn or torn.
(3) By locking the locking holes 50 provided at both ends in the length direction of the sheet-like member S to the locking claws 44 provided in the duct body 20, the sheet-like member S and each The contact state with the annular protrusion 26 is maintained, and the sheet-like member S can be prevented from coming off from the duct main body 20 and being rolled up during use.
(4) The locking width M in the longitudinal direction between the locking claws 44, 44 and the locking holes 50, 50 is larger than the width V of the annular projection 26 having the largest longitudinal width in each annular projection 26. Since it is set, the tip end portion 26A of each annular protrusion 26 and the sheet-like member S are reliably contacted.
(5) Since the sheet-like member S is formed from a porous material having a three-dimensional shape ventilation space or a thin film having a large number of two-dimensional through holes, air column resonance generated in the duct body 20 is suitably reduced. Can do.
(6) Even if the heat-shrinkable fiber is not used as in Patent Document 2, the sheet-like member S can be attached to the duct body 20 using the tension of the sheet-like member S. Moreover, since the annular protrusions 26 surrounding the openings 22 are provided on the outer surface of the duct main body 20, the sheet-like member S attached to the duct main body 20 is arranged in the circumferential direction and the longitudinal direction of the duct main body 20. Therefore, it is not necessary to form a sheet-like member using a special material obtained by forming a heat-shrinkable fiber into a cylindrical shape.

In order to confirm the performance of the intake duct D of the above-described embodiment, the inventor of the present application performed the following experiment to evaluate the performance of the intake duct D. The experimental conditions are as follows.
■ Duct body 20
・ Duct length: 600mm
・ Duct diameter: 65mm
■ Opening 22
・ Outer diameter: 20mm
-Number: 5-Forming position: Equally spaced in the circumferential direction at the intermediate portion in the length direction of the duct body 20-Annular projection 26
-Projection height H: 1.5 mm
・ Protruding width: 2mm
■ Sheet-shaped member S
・ Width: 30mm
・ Thickness: 0.8mm
-Material: Non-woven fabric (weight per unit area 100 g / m ² )
Sound is passed from the air outlet side of the intake duct D, and the noise level at a position 100 mm away from each opening 22 is measured. Then, the sound leakage amount at 120 Hz was compared in each of the following five types (1) to (5), assuming that sound leakage of the intake duct (comparative example) in which the opening 22 was not formed was 0 dB.
(1) Form example 1: When the opening 22 is provided but the sheet-like member S is not mounted
(2) Example 2: When the sheet-like member S is mounted without the annular protrusion 26
(3) Embodiment 3: When the protrusion height H of the annular protrusion 26 is T / 2
(4) Embodiment 4: When the protrusion height H of the annular protrusion 26 is T
(5) Example 5: When the protrusion height H of the annular protrusion 26 is 2T
(6) Comparative example: Without opening 22

  FIG. 7 is a graph showing the results of the experiment. From this experimental result, in the case of the first form example, sound leakage of about 10 dB was confirmed as compared with the comparative example. In the case of the form example 2, it was confirmed that the sound leakage amount was reduced to about 5 dB, which is half that of the form example 1. Moreover, in the case of the form example 3, the form example 4, and the form example 5, the sound leakage of about 1 dB was confirmed respectively. Therefore, from this experimental result, it was confirmed that the projecting formation of the annular protrusion 26 around each opening 22 has a great effect on reducing sound leakage. It was also confirmed that the difference in the protrusion height H of the annular protrusion 26 does not greatly affect the reduction of sound leakage. However, when the protrusion height H of the annular protrusion 26 is three times or more the thickness T of the sheet-like member S, both end portions in the width direction of the sheet-like member S are lifted from the outer surface of the duct body 20, and the sheet-like member There is a possibility that S may be caught by other devices or parts in the engine room. Accordingly, the protrusion height H of the annular protrusion 26 is desirably T / 2 ≦ H ≦ 3T, where T is the thickness of the sheet-like member S, as described above.

Furthermore, the inventor of the present application conducted an experiment for confirming the radiated sound characteristic from the air inlet and the transmitted sound characteristic from the opening 22 for the intake duct D of the above-described embodiment. The experimental conditions are as follows.
■ Duct body 20
・ Duct length: 700mm
・ Duct diameter: 60mm
■ Opening 22
・ Outer diameter: 20mm
-Number: 5-Forming position: 175 mm and 350 mm from the air inlet at equal intervals in the circumferential direction ■ Annular projection 26
-Projection height H: 0.8 mm
・ Distance G with the opening 22: 0.5 mm
■ Sheet-shaped member S
・ Width: 35mm
・ Thickness: 1.0mm
・ Material: Non-woven fabric (weight per unit area 200 g / m ² )
White noise is caused to flow through a speaker from the air outlet side of the intake duct D, and radiated sound from the air inlet is measured at a position 100 mm away from the center of the air inlet of the intake duct D, and the opening portion 22 is measured. The sound transmitted through the opening 22 was measured at a position 100 mm away from the opening.

  FIG. 8A is a graph showing the measurement result of the radiated sound from the air inlet, and FIG. 8B is a graph showing the measurement result of the transmitted sound from the opening 22. As shown in FIG. 8 (a), regarding the sound radiated from the air inlet, when the annular protrusion 26 is provided, the air column resonance generated from the entire duct body 20 is reduced, and a gentle radiated sound characteristic is obtained. Can be confirmed. In addition, when the annular protrusion 26 is not provided, noise is smaller at 400 Hz or lower and 500 to 900 Hz than when the annular protrusion 26 is provided, but there is a peak in the vicinity of 430 Hz, and a radiated sound of this frequency is felt strongly. . As shown in FIG. 8B, it can be confirmed that the transmitted sound from the opening 22 exhibits a smooth transmitted sound characteristic when the annular protrusion 26 is provided. On the other hand, when the annular protrusion 26 is not provided, the transmitted sound is larger at 600 Hz or less than when the annular protrusion 26 is provided, and there is a peak in the vicinity of 430 Hz, and the transmitted sound at this frequency is felt strongly. Therefore, it was confirmed that the projecting formation of the annular protrusion 26 surrounding the opening 22 is effective in reducing both the sound emitted from the air inlet and the sound transmitted through the opening 22.

(Example of change)
FIG. 9 is a cross-sectional view showing an intake duct D according to a modified example. The intake duct D of this modified example includes a rectangular tube-shaped duct body 20 in which openings 22 are formed, and a sheet-like member S that is mounted on the duct body 20 so as to cover the openings 22. The duct body 20 is a single member formed by, for example, blow molding and having a rectangular cross-sectional shape in the short direction. Then, two circular openings 22 are formed in the upper wall portion of the duct body 20, and one circular opening 22 is formed in each of the left and right side wall portions. One circular opening 22 is formed at each corner with each side wall.

  An annular protrusion 26 surrounding each opening 22 is formed on the outer peripheral surface of the duct body 20 so as to protrude from the outer surface of the duct body 20. As shown in FIG. 9A, the tip 26A of each annular protrusion 26 is formed in a substantially semicircular shape and is not angular. Further, the projecting height H of the annular protrusion 26 is such that the front end portion 26A of the annular protrusion 26 is uniformly in contact with the outer surface of the sheet-like member S attached with tension applied to the duct body 20. It is set on the assumption. That is, in the intake duct D of the modified example, the annular protrusions 26 formed on the upper wall part and each side wall part have a tip part 26A formed in a flat shape, and the annular protrusions 26 formed in a corner part are formed in a bent shape. ing. In other words, the front end portions 26A of the annular protrusions 26 arranged in the circumferential direction of the duct body 20 are formed so as to extend continuously in the circumferential direction of the duct body 20 in accordance with the outer surface shape of the duct body 20, and The shaped member S is easy to follow.

  On the other hand, the sheet-like member S is formed to a length that can be wound around the entire circumference of the duct body 20 in the circumferential direction. This sheet-like member S has a two-layer laminated structure, and the duct body 20 side when wound around the duct body 20 is the porous body, and the outside is the thin film. And, at one end in the length direction of the sheet-like member S (circumferential direction of the duct body 20), hook-like locking claws 46, 46 are formed to extend, and at the other end, Locking holes 52 and 52 with which the locking claws 46 and 46 can engage are formed so as to penetrate in the thickness direction of the sheet-like member S. Accordingly, the sheet-like member S is wound around and fixed to the duct body 20 in a tensioned state by a hooking structure that locks each locking hole 52 to the corresponding locking claw 46, and each annular protrusion 26 is fixed. Each of the openings 22 is covered by being in contact with the tip 26A. In addition, when the said porous body has sufficient thickness, a thin film does not need to have a through-hole. Therefore, the same effect as that of the intake duct D of the embodiment can be obtained in the intake duct D of the modified example.

Furthermore, the intake duct of the present application can be modified as follows.
(1) The number of openings 22 is not limited to six in the embodiment, but may be five or less (including one) or seven or more. The opening shape of the opening 22 is not limited to a circle, and may be an ellipse or a polygon.
(2) The annular protrusion 26 only needs to extend so as to surround the opening 22, and may extend to an ellipse or a polygon as long as it extends in an annular shape.
(3) The number of the locking claw portions 44, 46 and the locking hole portions 50, 52 formed is not limited to two, but may be three or more. When there are three or more locking claw portions 44, 46 and three locking hole portions 50, 52, the first locking portions located at both ends in at least the air flow direction in each locking claw portion 44, 46. 44, 46, and the respective locking hole portions 50, 52, at least the locking hole portions 50, 52 positioned at both ends in the air flow direction are provided at positions away from the annular protrusion 26 in the air flow direction, The sheet-like member S can be appropriately brought into contact with the distal end portion 26A of the protrusion 26.
(4) The sheet-like member S is not limited to one having a length L that is a half circumference in the circumferential direction of the duct body 20, and may be 1/3 round, 4/5 round, or the like.
(5) In the modified example, the intake duct D in which the opening 22 is provided in the corner portion between the upper wall portion and each side wall portion in the rectangular tube-shaped duct main body 20 is shown. You don't have to. Moreover, although the example which implemented the two-layer sheet-like member S of a porous body and a thin film was shown in the example of a change, this sheet-like member S may be a single | mono layer like the said Example.
(6) In FIG. 2 (a), the extending direction of the locking claws 44, 44 in the second duct half body 40 having a semicircular cross-sectional shape is shown, but as shown in FIG. In the case of the second duct half 40 having an opening 22 and an annular projection 26 formed only in a flat portion with a cross-sectional shape of a letter shape, the extending direction of the locking claws 44, 44 is as follows. Stipulated in That is, both corner portions sandwiching the flat portion of the second duct half 40 are point P1 and point P2, respectively, and the tip of the annular protrusion 26 adjacent to one of the corner portions (left corner portion in FIG. 10). Let the part 26A be a point P3. Under such conditions, each of the locking claws 44, 44 has an imaginary circle passing through the three points P1, P2, P3, and a tangent of the imaginary circle at the point P1 and a tangent of the imaginary circle at the point P2. Is also formed and extended so as to extend inward in the radial direction of the duct body 20. Thus, when the locking claw portions 44 and 44 are locked to the locking holes 50 and 50 and the sheet-like member S is attached to the second duct half body 40, The sheet-like member S comes into contact with no gap.

20 Duct body, 22 opening, 24 opening end, 26 annular projection (projection), 26A tip 44, 46 locking claw (first locking), 50, 52 locking hole (second locking) ), M Locking width S Sheet-like member, V width

Claims (7)

A cylindrical duct main body having an opening, and a sheet-like member attached to the duct main body so as to cover the opening and having air permeability are disposed in an intake portion of an engine mounted on an automobile. In the intake duct,
On the outer surface of the duct body, a plurality of the openings are provided side by side in the circumferential direction of the duct body , and protrusions formed so as to surround each opening are provided,
The air intake duct is characterized in that the sheet-like member is attached to the duct body with tension applied so as to contact the tip of each projection. The tip of each projection is formed so as to extend continuously in the circumferential direction of the duct body according to the outer surface shape of the duct body,
Intake duct according to claim 1, wherein said sheet-like member, no gap is uniformly in contact with the tip portion is deformed along the distal portion of each projection. 3. The intake duct according to claim 1, wherein the sheet-like member is fixed to the duct body only at both ends in the circumferential direction of the duct body when mounted on the duct body. The duct body includes a first locking portion,
The sheet-like member includes second locking portions at both ends in the circumferential direction of the duct body,
The hook structure due to pores with the claw of the first engaging portion and second engaging portion, of claim 3, wherein said sheet-like member is wound fixed to the duct body while applying a tension in the circumferential direction Intake duct. The sheet-like member includes a first locking portion at one end in the circumferential direction of the duct body, and a second locking portion at the other end.
2. The sheet-like member is wound and fixed around the entire circumference of the duct body in a state in which tension is applied in the circumferential direction by a hooking structure using holes and claws of the first locking portion and the second locking portion. Or the intake duct of 2 . The first locking portion and the second locking portion are provided apart from each other in the air flow direction of the duct body,
A first locking portion positioned at both ends in at least the air flow direction in each first locking portion, and a second locking portion positioned at both ends in at least the air flow direction in each second locking portion, The intake duct according to claim 4 or 5 , wherein the intake duct is provided at a position deviated from the protrusion in the air flow direction. The intake duct according to any one of claims 1 to 6 , wherein the sheet-like member is formed of a porous material.

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