JP5240857B2 - Ventilation duct - Google Patents

Description

The present invention relates to a ventilation duct that allows air to flow inside a duct. In particular, the present invention relates to a ventilation duct in which a through-hole communicating with the inside and outside of the duct wall is provided in the duct wall.

Ventilation ducts are used as members that form a series of ventilation duct systems, particularly in the intake systems of internal combustion engines for automobiles, intake systems of fuel cells, cooling air blowing systems and air conditioning systems for cooling secondary batteries, etc. Has been. In such a duct system, a duct made of a non-breathable material such as a synthetic resin, a metal plate, or a pipe is generally used for the duct wall. For some time, it has been desired to reduce noise by propagating air or by air column resonance occurring in the duct system.

Therefore, in these ventilation ducts, a duct wall called a tuning hole is used to prevent / suppress the air column resonance generated in the duct system, or to dissipate and attenuate the noise propagating in the duct to the outside of the duct. There may be a case where a through-hole penetrating is provided.

In many cases, the tuning hole is simply provided with a through hole in the duct wall of the ventilation duct. However, as another mode in which the tuning hole is provided, for example, as disclosed in Patent Document 1, the tuning hole is provided. 2. Description of the Related Art There is known an intake duct configuration in which a protector member to be covered is attached to face a tuning hole so that a gap is provided between the protector member and the duct.

JP 2001-41122 A

On the other hand, not only the above-mentioned acoustic performance but also the performance of the strength side of the ventilation duct such as its strength and durability, and the performance of reducing the ventilation resistance of the airflow flowing through the inside are emphasized for these ventilation ducts. In particular, the reduction of ventilation resistance is particularly important in the intake duct for supplying a large amount of intake air to the internal combustion engine and the fuel cell through the intake system, and is also important in the air conditioning duct and the cooling air blowing duct. .

However, it has been found that when a through hole such as a tuning hole is provided in the ventilation duct, air is sucked from the through hole, so that the airflow inside the intake duct is disturbed and the ventilation resistance increases.

Accordingly, an object of the present invention is to reduce the ventilation resistance of air flowing through the ventilation duct in a duct having a through hole provided in the duct wall.

As a result of intensive studies, the inventor has found that if a protruding portion protruding toward the inside of the duct is formed immediately downstream of the through hole provided in the ventilation duct, deterioration of the ventilation resistance due to the provision of the through hole can be suppressed. The present invention has been completed.

The present invention is a straight tubular ventilation duct for constituting a ventilation path for sucking air, and the ventilation duct penetrates the duct wall so that air can flow from the outside of the duct to the inside of the duct. In the circumferential direction of the duct, at the same position as the through hole and on the downstream side of the intake passage of the through hole, a protrusion is formed so that the inner peripheral surface of the duct wall protrudes toward the inside of the duct. This is a featured ventilation duct.

In the present invention, it is preferable that the upstream portion of the protruding portion is provided adjacent to the downstream end portion of the through hole so as to rise from the non-projecting portion of the duct wall (Claim 2). It is preferable that the downstream portion is provided in a shape such that the protruding amount of the protruding portion gradually decreases toward the downstream side (Claim 3).

According to the present invention, in a straight tubular ventilation duct having a through-hole formed in the duct wall, the flow inside the duct is prevented from being disturbed by the flow from the through-hole and the ventilation resistance is deteriorated. The airflow resistance of the air flowing through can be reduced.

In addition, the upstream portion of the protruding portion is provided adjacent to the downstream end portion of the through hole so as to rise from the non-projecting portion of the duct wall, or the protruding amount of the protruding portion as the downstream portion of the protruding portion goes downstream. Ventilation resistance can be more effectively reduced by providing it in a shape that gradually reduces.

It is a perspective view of an air intake duct which is an embodiment of the present invention. It is an expanded sectional view near the penetration hole of the air intake duct of the embodiment of the present invention. It is a figure which shows the detailed shape of the through-hole and protrusion part of the intake duct of embodiment of this invention. It is a schematic diagram which shows the flow of the through-hole vicinity when there is no protrusion part. It is a schematic diagram which shows the flow of the through-hole vicinity when there exists a protrusion part. It is a figure which shows the flow-velocity distribution of the cross section in the through-hole downstream position in the intake duct of embodiment of this invention. It is a figure which shows the flow-velocity distribution of the cross section in the through-hole downstream position in the intake duct of a comparative example. It is a figure which shows the scale of the flow velocity in the flow-velocity distribution map of FIG. 6 and FIG. It is a figure which shows the other shape of the through-hole and protrusion part of the intake duct of embodiment of this invention. It is a figure which shows the intake duct of other embodiment of this invention. It is a figure which shows the intake duct of other embodiment of this invention. It is a figure which shows the streamline of the flow from the through-hole of embodiment of this invention. It is a figure which shows the flow line of the flow from the through-hole of embodiment of this invention from another viewpoint.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing the appearance of an intake duct 1 of the present invention. In FIG. 2, the cross section along the duct axial direction of the through-hole 3 vicinity of the intake duct 1 of this invention is expanded and shown. The ventilation duct of the present invention includes a part of an intake system for supplying air to an automobile engine (internal combustion engine), a part of an intake system for supplying air to a fuel cell, a battery, and the like. Used as part of the air duct for cooling. In the present embodiment, the intake duct 1 is an intake duct that forms part of an intake system for supplying air to the internal combustion engine, and the intake duct 1 is connected to the upstream side of another duct member or an air cleaner. It is a duct member.

The intake duct 1 is provided with a through hole 3 penetrating the duct wall 2 in the duct body 2 having a hollow cylindrical duct wall formed of a synthetic resin (polypropylene resin in the present embodiment), and further passes through the intake duct. It is a duct member formed so that the protruding portion 4 protrudes into the duct at a position on the downstream side (directly downstream) of the through hole 3 in the flowing direction of the flowing air. The duct body 2 is a hollow member through which air flows, and in this embodiment, a funnel portion 21 for sucking air from the open atmosphere into the duct is formed at the upstream end portion thereof. At the downstream end thereof, a cylindrical duct portion (mouth portion) 22 is provided for connecting with other subsequent duct components, connector members, etc. and forming a series of air flow paths together with the other members. ing. The intake duct 1 may be provided with a mounting member (not shown) as necessary.

The through hole 3 provided so as to penetrate the duct wall is a circular through hole in the present embodiment, and the internal space and the external space of the duct body 2 communicate with each other through the through hole 3. By providing the through hole 3, air column resonance generated in an intake system connected with a series of ducts can be prevented or suppressed. The through hole 3 is effective in the axial direction of the duct for preventing and suppressing air column resonance. It is provided at a position and size (preferably about 3 mm to 12 mm) and functions as a so-called tuning hole.

When intake is performed through the intake duct 1, as a main air flow path, air is sucked from the funnel portion 21, flows through the duct internal space, and flows downstream through the duct mouth portion 22. In the present invention, the intake duct 1 is used in such a manner that the static pressure inside the duct becomes negative with respect to the atmospheric pressure outside the duct, that is, the air is sucked. As air is sucked into the intake system from the main flow path of the intake duct 1, the air is secondarily sucked from the through hole 3, and merges with the main flow sucked from the funnel 21 to be downstream. Air will flow through.

The intake duct 1 according to the present invention is characterized in that a protrusion 4 is provided on the downstream side of the flow of the pipe through hole 3. The protruding portion 4 is a portion formed so as to protrude toward the duct inner peripheral side as compared with the non-projecting portion 23 in the duct inner peripheral surface that defines the duct internal space.

The protruding portion 4 is provided on the downstream side of the through hole 3 in the vicinity of the through hole and at a position where the through hole 3 and the circumferential position of the duct substantially coincide with each other. If the protruding part is greatly separated from the through hole or the circumferential position is shifted, the ventilation resistance reduction effect is reduced. In the present embodiment, the most upstream part of the protruding part 4 is provided so as to be adjacent to the downstream edge part of the through hole 3.

In this embodiment, the protrusion 4 is integrally formed with the duct body 2 so as to have the following inner peripheral surface shape. That is, as shown in FIG. 3, when viewed from the radial direction of the duct (see FIG. 3 (a)), the upstream side (through hole side) is round, and the downstream side has a smooth tear-shaped shape with a spindle shape, The length L of the protrusion 4 along the flow direction is about four times the through-hole diameter d1, and the width W of the protrusion 4 in the direction perpendicular to the flow direction is the same as the diameter d1 of the through-hole 3, When viewed along the direction (see FIG. 3B), the protrusion height H of the protrusion 4 is set to be approximately the same as the diameter d1 of the through hole 3. Moreover, the cross-sectional shape of the protrusion seen from the direction along the main flow direction of the intake air is a semicircular shape (see FIG. 3C). That is, the three-dimensional shape of the protrusion 4 is spherical on the upstream side of the portion where the protrusion height is maximum, and the protrusion 4 rises so as to be adjacent to the downstream edge of the through hole 3, while on the downstream side Then, the spindle has a spindle shape (or conical shape) along the flow direction, and the protruding height and width of the protruding portion gradually decrease toward the downstream side.

There is no restriction | limiting in particular as a material which comprises the intake duct 1, The various material which can form such a duct can be used. For example, thermoplastic synthetic resins such as polypropylene resin, polyamide resin, and polyethylene resin, relatively hard synthetic resins such as thermosetting synthetic resins, relatively soft elastomers such as rubber and thermoplastic elastomers, aluminum and iron, etc. The metal material can be illustrated. Especially, since a duct member can be efficiently shape | molded by the blow molding method or the injection molding method, synthetic resin materials, such as a thermoplastic resin, rubber | gum, and a thermoplastic elastomer, can be used preferably.

The intake duct 1 can be manufactured by a known method. For example, in the case of the intake duct 1 of the present embodiment, the duct body 2 in which the projecting portions 4 are integrally formed is formed by a known blow molding method, and the funnel portion 21, the mouth portion 22, and the opening hole 3 are opened. Thus, the intake duct 1 can be obtained.

In addition, the method of manufacturing the intake duct 1 is not limited to the blow molding method, and can be performed by an injection molding method. In particular, when the accuracy of the inner peripheral surface shape of the duct is required, the injection molding method may be used. preferable. Further, the protrusion 4 does not necessarily have to be integrally formed with the duct body 2 at the same time, and the duct body 2 and the protrusion 4 are manufactured separately as in a second embodiment to be described later, and are bonded and integrated later. You may make it.

The effect of the ventilation duct of this invention is demonstrated.
In the present invention, since the protrusion 4 provided on the downstream side of the tube passage hole 3 does not hinder the function of the through hole itself, the through hole exhibits the effect that was initially expected. The effect of improving the acoustic characteristics of the duct system is demonstrated as a hall, preventing and suppressing air column resonance of the duct system, and radiating sound propagating inside the duct to the outside to reduce noise propagating to the funnel side Can do.

Furthermore, in the intake duct 1 of the present invention, the provision of the protrusion 4 can reduce the ventilation resistance when air is sucked by the intake system.
First, the air flow inside the duct in the conventional intake duct not provided with the protrusion 4 will be described. As shown in FIG. 4, the flow from the through hole merges with the main flow flowing from the left side of the drawing. In the downstream area of the through hole, a stagnation region or vortex is generated, and the flow from the vortex, stagnation, or through hole compresses the main flow path in the duct, increasing the airflow resistance. End up.

In the intake duct 1 of the present invention, the protrusion 4 is provided immediately downstream of the through hole 3, thereby preventing or suppressing the generation of vortices and stagnation areas due to the flow from the through hole 4 as shown in FIG. 5. Thus, in the downstream region of the through hole, the flow from the through hole is prevented from greatly entering the inside of the duct, and flows along the duct wall. Therefore, the degree to which the flow path of the main flow in the duct is compressed by the flow from the through hole is alleviated, and the deterioration of the ventilation resistance is suppressed.

In order to obtain such a ventilation resistance reducing effect, a particularly preferable protruding portion shape will be described below. However, if the protruding portion 4 is too small, the improvement effect of the ventilation resistance tends to be reduced, while if the protruding portion is too large, a duct is formed. Since the cross-sectional area may be reduced and the improvement of the ventilation resistance may be hindered, the size of the protrusion is preferably set to the following level.

When the length d1 (the diameter in this embodiment) of the through hole in the flow direction of the through hole is sufficiently smaller than the duct diameter D (for example, in the case of d1 <D / 3), the protrusion height of the protrusion is as follows. The length H is about the same as the length d1 of the through-hole flow direction, that is, 0.5 * d1 <H <2.0 * d1, more preferably about 0.7 * d1 <H <1.5 * d1. preferable.
Further, when the through hole is larger than the duct diameter, that is, when the length d1 (the diameter in the present embodiment) of the through hole in the flow direction is not sufficiently small with respect to the duct diameter D (for example, d1> D / 2), the height H of the protrusion is preferably about H <D / 3, more preferably about H <D / 4, with respect to the duct diameter D.

The width W of the protrusion is preferably about 0.5 * d1 <W <2.0 * d1, more preferably about 0.7 * d1 <W <1.5 * d1, where the diameter of the through hole is d1. . In the present invention, the flow from the through hole spreads from the upper surface to the side surface of the protruding portion 4 and flows along the surface of the protruding portion, and the flow from the through hole is dispersed and weakened. There is also an effect of preventing stagnation, and if the width of the protruding portion is too larger than the through hole, this effect is weakened and the effect of reducing the ventilation resistance is lowered. Further, the length L in the flow direction of the protrusion is preferably about 1 to 10 times, preferably about 2 to 7 times the through-hole diameter d1. If the length is too short or too long, the airflow resistance reduction effect is reduced.

Also, so that the flow from the through hole flows without peeling along the surface of the protrusion, the protrusion is formed to have a smooth surface such as a smooth curved surface such as a spherical surface or an elliptical surface. It is preferable to do.

In the upstream portion 41 of the protruding portion 4, the position where the protruding portion 4 rises from the non-projecting portion 23 of the duct body is provided so as to be adjacent to the downstream edge of the through hole 3 as close as possible. Although it is preferable to reduce the resistance, the upstream rising portion of the protrusion and the downstream edge of the through hole may be separated from each other. In order to reduce the ventilation resistance, it is preferable that the separation distance in the case of the separation be equal to or less than the protrusion height H of the protrusion.

In addition, in the upstream portion 41 of the protrusion 4, it is preferable to provide a protrusion so that the protrusion rises at a predetermined angle from the non-protrusion of the duct body. It is preferable that the angle α of the boundary between the portions is 45 degrees to 90 degrees, more preferably 60 degrees to 90 degrees.

By providing the upstream portion 41 of the protruding portion adjacent to the downstream end of the through hole so as to rise from the non-projecting portion of the duct wall, the air flow flowing from the through hole flows along the surface of the protruding portion. The separation of the airflow flowing from the through hole is prevented, the stagnation and vortex area generated downstream of the through hole is reduced, and the ventilation resistance can be effectively reduced.

Further, in the downstream portion 42 of the protruding portion 4, the gradient of the protruding portion downstream side portion with respect to the non-projecting portion of the duct wall is ½ or less to the extent that the protruding amount of the protruding portion gradually decreases toward the downstream side. In order to reduce the ventilation resistance, it is more preferable to set it to 1/3 or less.

By forming the downstream portion 42 of the protruding portion into a shape in which the protruding amount of the protruding portion gradually decreases toward the downstream side, the area of stagnation and vortex generated downstream of the through hole is reduced, and effective ventilation is achieved. Resistance can be reduced.

The result of verifying the ventilation resistance suppressing effect of the present invention by numerical fluid simulation will be described. The numerical fluid simulation was performed for a duct shape similar to the intake duct 1 shown in FIG. The specific dimensions of the intake duct are an overall length of 450 mm, a cross section of the duct body is an ellipse with a major axis of 45 mm and a minor axis of 26 mm (corresponding to a circular section with a sectional area of 36 mm in diameter), and the funnel part has a major axis of 65 mm and a minor axis. It is an ellipse of 46 mm (equivalent to a circular cross section with a diameter of 54 mm in cross-sectional area), and in a 150 mm section near the downstream end of the duct, the duct cross section is changed from an ellipse with a major axis of 45 mm and a minor axis of 26 mm to a circular cross section with a diameter of 45 mm. It is an intake duct that gradually changes while expanding in a tapered shape. Further, the overall shape of the intake duct is close to a substantially straight duct, but a gentle bend is given in the gradual change section. The through hole 3 is provided with a diameter of 10 mm at a position 207 mm from the downstream end of the duct. The specific dimensions of the protrusion shape were a protrusion height of 10 mm, a width of 10 mm, and a length of 30 mm, and were provided in a smooth teardrop shape so as to stand up adjacent to the downstream edge of the through hole. Moreover, although the shape of a duct and the shape of a through-hole are the same, the intake duct which is not provided with the protrusion part was made into the comparison shape.

For the intake ducts of the present embodiment and comparative example of the above-described shape, a numerical fluid simulation was performed so that the amount of air sucked from the downstream end of the duct was 48 liters / second, and the center of the duct at the downstream end of the duct The static pressure (differential pressure with respect to atmospheric pressure) was obtained and the ventilation resistance was evaluated. According to the analysis result, in the intake duct of the embodiment of the present invention provided with the protrusion, the airflow resistance is 948.2 Pa, and in the comparative intake duct without the protrusion, the airflow resistance is 1086.5 Pa. By providing the portion 4, the ventilation resistance was reduced by 12.7%. The flow rate flowing from the funnel portion 21 accounts for 92.7% of the total flow rate, and the flow from the funnel portion 21 is the main flow inside the duct.

FIGS. 6 and 7 show visualization of the flow in the duct calculated by the numerical fluid simulation. 6 and 7 are diagrams showing the flow velocity distribution in the duct cross section at a position 50 mm upstream from the downstream end of the intake duct 1, and FIG. 6 shows the flow velocity distribution in the intake duct of the embodiment of the present invention. FIG. 7 shows the flow velocity distribution in the intake duct of the comparative example. In any of the drawings, the position in the circumferential direction of the duct provided with the through hole (in FIG. 6, the through hole and the protruding portion) is the position on the left side of the drawing (the position from 8 o'clock to 9 o'clock in the case of an analog clock) . Moreover, the scale of the flow velocity in these flow velocity distribution diagrams is shown in FIG. 8, and FIG. 6 and FIG. 7 indicate that the flow velocity is higher as the color becomes lighter.

As is clear by comparing FIG. 6 and FIG. 7, in the embodiment of the present invention shown in FIG. 6, the region where the flow velocity is low in the downstream portion of the through hole is small, the region of the main flow is wide, and The maximum flow velocity in the main flow region is suppressed, and the gradient of the flow velocity distribution is gentle. On the other hand, in FIG. 7 of the comparative example, a region where the flow velocity is very slow is generated in the downstream portion of the through hole, and as a result, the region where the flow velocity is low is large and the region where the main flow flows is narrowed. It can be seen that there is a flow with a large maximum flow velocity, and the gradient of the flow velocity distribution is steep. It is assumed that such a difference in flow field appears as a difference in ventilation resistance.

12 and 13 show flow lines of flow from the through hole in the embodiment of the present invention. FIG. 12 is a streamline viewed in a cross section including a through hole and a protrusion, and FIG. 13 is a streamline viewed from the through direction of the through hole. As shown in FIG. 12, the flow sucked from the through hole flows along the surface of the protrusion, the separation of the flow is suppressed, the flow direction changes toward the lower side of the figure, and the funnel It is observed that the main flow path flowing from the center is not narrowed. Further, as shown in FIG. 13, it is observed that the flow sucked from the through hole flows so as to spread slightly in the width direction along the surface from the upper surface to the side surface of the protrusion.

The present invention is not limited to the above embodiment, and can be implemented with various modifications. Other embodiments of the present invention will be described below. However, in the following description, portions different from the above embodiment will be mainly described, and the same portions will be denoted by the same reference numerals and description thereof will be omitted. To do.

FIG. 9 shows another embodiment of the through hole and the protrusion. In the present embodiment, the through-hole 5 is a square hole having a substantially square shape, and the protruding portion 6 is formed by bonding and integrating a protruding member 61 formed separately from the duct body 2 to the inner peripheral surface of the duct. Has been. The shape of the upstream portion of the projecting portion 6 is a conical shape having a central axis extending in the radial direction of the duct, and rises at an angle of about 60 degrees with respect to the non-projecting portion of the duct wall. The shape is a triangular prism shape along the flow direction so that the height is constant, and the downstream portion of the protruding portion is a triangular pyramid shape whose protruding amount gradually decreases toward the downstream.

Also in this embodiment, it is prevented / suppressed that the airflow inside the duct is disturbed by the flow flowing from the through hole 5 and the ventilation resistance is increased. That is, the present invention can be implemented even if the shape of the through hole or the shape of the protruding portion is changed, and the through hole is used for the purpose of reducing the manufacturing efficiency, the airflow resistance, or for other purposes. It can be carried out by changing the shape of the hole or the protrusion.

Further, in the description of the above embodiment, the duct cross-sectional shape of the duct main body 2 is circular and the intake duct 1 in which the duct is substantially linear has been described. However, the present invention is not limited thereto, and the cross-sectional shape of the duct is The shape may be an ellipse, an ellipse, a quadrangle, a polygon, or the like, and the duct may be bent in the length direction.

In the description of the above embodiment, the through hole 3 and the through hole 5 are described as being through holes opened to the outside of the air intake duct. However, for the purpose of further improving the duct silencing performance and other purposes. It is also possible to carry out by modifying the structure outside the through hole.

For example, in FIG. 10, a breathable porous material (for example, a fiber aggregate such as a woven fabric or a nonwoven fabric or a foamed resin sponge) is attached so as to cover the through hole 3 provided in the duct body 2, 3 shows an example in which a so-called porous duct is configured.

FIG. 11 shows an example in which the sub duct 8 is provided so as to be continuous with the through hole 3 provided in the duct body 2. This embodiment is a particularly preferable embodiment for sucking air having a lower temperature through the sub duct 8 or transmitting the sound inside the duct to a predetermined portion using the sub duct 8. Furthermore, when a valve body is provided in the sub duct 8, it is possible to adjust the amount of air flowing through the sub duct and the degree of sound propagation.

Also in the embodiment as shown in FIG. 10 and FIG. 11, it is the same that the ventilation resistance of the duct is reduced by providing the protrusion 4 on the downstream side of the through hole 3. That is, in the practice of the present invention, the purpose of providing the through hole in the duct wall is not limited to the purpose of improving the acoustic characteristics of the duct such as a so-called tuning hole, but can be various purposes.

In the description of the above embodiment, the embodiment in which the present invention is applied to the intake duct used in the intake system of the internal combustion engine for automobiles has been described. However, as is clear from the above description, the implementation of the present invention has been described. However, the present invention is not limited to this, and can be implemented in a ventilation duct generally used in a duct system used in a form in which air is sucked by the duct system. That is, a duct for sucking air supplied to a household fuel cell, a ventilation duct for guiding cooling air for cooling a secondary battery of an electric vehicle, and an air conditioner for guiding air sucked by an air conditioner such as an air conditioner. The ventilation duct of this invention can be used for a duct etc.

The ventilation duct of the present invention can be used for an intake system of an internal combustion engine or a fuel cell, a duct system such as a battery cooling system or an air conditioning system. The ventilation duct of the present invention can suppress an increase in ventilation resistance when a through hole is provided in the duct wall, and has high industrial utility value.

1 Intake (ventilation) duct 2 Duct body 3 Through hole 4 Protruding part 5 Through hole 6 Protruding part 7 Breathable porous material 8 Sub duct

Claims (3)

A straight tubular ventilation duct for configuring a ventilation path for sucking air,
The ventilation duct is provided with a through hole so that air can flow from the outside of the duct to the inside of the duct through the duct wall.
Ventilation characterized in that a protrusion is formed so that the inner peripheral surface of the duct wall protrudes toward the inside of the duct at the same position as the through hole in the circumferential direction of the duct and on the downstream side of the intake passage of the through hole. duct. The ventilation duct according to claim 1, wherein the upstream portion of the projecting portion is provided adjacent to the downstream end portion of the through hole so as to rise from the non-projecting portion of the duct wall. The ventilation duct according to claim 1 or 2, wherein the downstream portion of the protruding portion is provided in a shape such that the protruding amount of the protruding portion gradually decreases toward the downstream side.