JP4542470B2 - Air intake duct - Google Patents

Description

  The present invention relates to an intake duct, and more particularly, an air flow area of an air flow passage connected to an air intake portion of an engine and defined inside the duct body is increased or decreased according to the rotational speed of the engine. The present invention relates to an intake duct that is changed.

  In recent years, automobiles produced in recent years are equipped with various safety devices such as airbag devices and brake devices, while improving the safety performance by taking measures to increase the rigidity of the body and chassis. Therefore, since the vehicle weight tends to increase inevitably, it is required to increase the output of the engine in order to ensure traveling performance. However, in today, when environmental problems are highlighted, improvement of environmental performance such as improvement of fuel consumption, exhaust gas cleanup, noise reduction, etc. is a major issue, and improvement of output without increasing the displacement is aimed at. Countermeasures are sought after.

  For example, FIG. 12 is an explanatory sectional view showing an air supply part of an engine EG mounted in an engine room 12 of an automobile, and the air required for rotational driving of the engine EG is the front part of the vehicle body 10. The air is taken in from the intake duct D1 assembled to the air cleaner AC and cleaned by the air cleaner AC, and then supplied to the engine EG. In order to improve the output of the engine EG in such a configuration, the air flow resistance of the intake duct D1 that takes in the external air is reduced as much as possible so that the taken-in external air is smoothly supplied to the engine EG. The method is considered effective. Specifically, while the duct body 20 of the intake duct D1 is enlarged, the communication area of the air intake port 22 is increased and the cross-sectional area (air flow area) of the air flow passage defined inside If a large value is set, it is easy to increase the engine output. However, when the intake duct D1 is increased in size, there arises a new problem that noise such as engine noise (particularly combustion noise) and intake noise released from the air intake port 22 to the outside of the vehicle increases.

Therefore, for example, as shown in FIG. 13, a rotary shutter type valve 26 is arranged inside the duct body 20, and the air flow area in the air flow passage 24 is changed by displacing the posture of the valve 26. An air intake duct D1 is proposed. In the intake duct D1 of this type, when the rotational speed of the engine EG is low during normal traveling or the like, the valve 26 is displaced to the first posture indicated by the solid line in FIG. Engine noise emitted from the intake port 22 is reduced. Further, when the rotational speed of the engine EG increases during acceleration traveling or the like, the valve 26 is rotated and displaced toward the second posture indicated by the two-dot chain line in FIG. The intake of external air is allowed to cope with the high output of the engine EG. An intake duct having such a variable intake structure is disclosed in Patent Document 1, for example.
Japanese Patent Laid-Open No. 11-82202

  By the way, the above-described conventional intake duct D1 is substantially perpendicular to the air flow direction in the air flow passage 24 when the valve 26 is displaced in the first posture, so that the air flow resistance is extremely high. It deteriorated and there was a problem that sufficient external air could not be taken in. This is because, as shown by a broken line in FIG. 14, air separation greatly occurs at the edge portion of the valve 26, so that a substantial effective air circulation area is reduced. In order to eliminate such an inconvenience, the distance between the end edge of the valve 26 in the first posture and the inner wall surface of the duct may be increased. However, this increases the air circulation area. This makes it impossible to reduce engine noise.

  Therefore, as illustrated in FIG. 15, by adding a bypass path 28 to the duct body 20, the valve 26 is set to the first posture during low rotation so that external air is taken in via the bypass path 28. An intake duct D1 is also proposed in which the valve 26 is set to the second posture during high rotation so that external air is taken in from both the duct body 20 and the bypass passage 28. However, in the case of the intake duct D1 having such a configuration, there is a problem that the manufacturing cost increases due to an increase in the number of parts, and there is a disadvantage that the external size becomes large and a large installation space has to be secured, such as a small car. In some cases, it could not be adopted.

  Further, in the case of the rotary shutter type valve 26 described above, since the rotational displacement amount of the valve 26 and the increase / decrease amount of the air flow area are not proportional, the intake amount of external air cannot be controlled appropriately, There is also a problem that affects engine output characteristics. For example, as illustrated in FIG. 16, in the case of a 30 degree posture (shown by a broken line) rotated by 30 degrees with respect to the valve 26 (shown by a solid line) in the first posture, an increase in the air circulation area with respect to the amount of rotation. The amount is slight. However, when the posture is rotated from the 30 degree posture (displayed with a broken line) to the 60 degree posture (displayed with a one-dot chain line), the amount of increase in the air circulation area becomes considerably large. In the case of rotation to (two-dot chain line display), the amount of increase in the air circulation area is doubled at once. Further, when the valve 26 is in the first posture and a posture close thereto, not only the air flow resistance increases as described above, but also the drawback that the air flow is greatly disturbed on the rear side (downstream side) of the valve 26 is pointed out. Is done.

  Furthermore, although the noise of the engine EG varies depending on the type of engine EG, the displacement, etc., the frequency changes according to the rotational speed of the engine EG, and generally the frequency tends to increase as the rotational speed increases. It is in. For this reason, in order to effectively reduce the broadband noise according to the engine speed, it is necessary to install a large resonator having a plurality of resonance chambers. There were some restrictions. Further, in the case of the intake duct D1 illustrated in FIG. 15, since the bypass path 28 is always open, the engine noise is emitted to the outside through the bypass path 28. .

  Therefore, the present invention can appropriately control the amount of external air taken in according to the engine speed, and at the same time, can effectively reduce engine noise having a different frequency depending on the engine speed. An object of the present invention is to provide an air intake duct that can reduce the manufacturing cost.

In order to solve the problem and achieve the intended purpose, the invention according to claim 1 of the present application is
In the intake duct connected to the air intake portion of the engine, the air flow area of the air flow passage defined inside the duct body is increased or decreased according to the rotational speed of the engine.
An air circulation port formed in a required portion of the air flow passage;
A valve body that is arranged on the downstream side of the air circulation port and is capable of sliding in the air circulation direction, and the side facing the air circulation port is bulged into a substantially cone shape;
A space defined as the outside of the air flow passage, spatially communicating with the air flow passage through a communication port established in the duct body, and functioning as a resonance chamber;
A shutter member that is provided outside the valve body, faces the communication port, and adjusts the communication area of the communication port in accordance with the sliding movement of the valve body;
The gist is that the valve body slides in accordance with the rotational speed of the engine to increase or decrease the air flow area at the air flow port and increase or decrease the communication area of the communication port.

  Therefore, according to the first aspect of the invention, the valve body slides according to the engine speed, so that the air flow area of the air flow passage can be changed, and the shutter member provided on the valve body The communication area between the air flow passage and the space can be changed continuously or intermittently. Therefore, the intake of air necessary for the engine is allowed, and at the same time, the engine noise whose frequency changes with the change in the rotational speed can be suitably reduced.

The invention according to claim 2 is the invention according to claim 1, wherein the valve body is attached to a valve installation portion provided in the duct body, and the slide movement along the air flow direction of the air flow passage is performed. The gist is that it is possible.
Therefore, according to the invention according to claim 2, when the valve body slides along the air flow direction of the air flow passage, the posture does not change with respect to the flow of the taken-in external air. It is possible to prevent the airflow flowing through the interior from being disturbed.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the valve body is always provided with the air flow by an urging member disposed between the valve body and the duct body. It is arranged in a state of being elastically biased toward the mouth side,
When the engine is running at a low speed, the urging force of the urging member is close to the air circulation port side, and when the engine is rotating up, the urging force of the urging member is resisted by the pressure of external air taken in The gist is to separate from the air circulation port.

  Therefore, according to the third aspect of the present invention, a separate valve moving mechanism or the like is not particularly required, and the whole is made compact and the product cost is prevented from increasing.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the urging force of the urging member stops and holds the valve body at a position closest to the air circulation port when the engine is rotating at a low speed. The gist of the invention is that the valve body is set to a size that allows the valve body to move away from the air circulation port as the engine rotates.
Therefore, according to the fourth aspect of the present invention, a separate drive mechanism or the like is not particularly required, and the whole is made compact and the product cost is prevented from increasing.

The invention according to claim 5 is the invention according to claim 1 or 2, wherein the valve body is connected to a valve moving mechanism that is driven based on the detected rotational speed of the engine, and the rotation of the engine The gist is to slide in conjunction with the number.
Therefore, according to the fifth aspect of the invention, it is possible to control the movement of the valve body with high accuracy in accordance with the engine speed, and the amount of increase and decrease in the air flow area and the communication area with the engine speed. It is possible to accurately control the amount of increase / decrease.

The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the sliding movement amount of the valve body and the increase / decrease amount of the air circulation area of the air circulation port associated therewith are substantially equal. The gist is that it is set to be proportional.
Therefore, according to the sixth aspect of the present invention, the engine speed and output directly increase, and ideal engine output characteristics can be obtained.

The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the sliding movement amount of the valve body and the increase / decrease amount of the communication area of the communication port associated therewith are substantially proportional. The gist is that it was set to be
Therefore, according to the invention which concerns on Claim 7, the reduction efficiency of the engine noise from which a frequency changes according to the rotation speed of an engine can be improved effectively.

  The intake duct according to the present invention can appropriately control the amount of external air taken in according to the engine speed, and effectively reduce engine noise generated at different frequencies according to the engine speed. It is possible to achieve a beneficial effect such that the manufacturing cost can be reduced.

  Next, an intake duct according to the present invention will be described below with reference to the accompanying drawings by way of preferred embodiments.

  FIG. 1 is a plan view showing an intake duct according to a preferred embodiment in a partially broken and omitted state, and FIG. 2 shows a main part of the intake duct illustrated in FIG. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 1, showing a state where the air circulation area and the communication area are minimized by the valve body, and FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. is there. FIG. 5 is a cross-sectional view of the intake duct shown in a state where the air circulation area and the communication area are maximized by the valve body.

  The intake duct D of the present embodiment is connected to an air intake portion of the engine EG, and increases or decreases the air flow area S of the air flow passage 58 defined in the duct body 20 according to the rotational speed of the engine EG. It is intended to change. That is, as in the case of FIG. 12, it is assembled to the front side of the engine room 12 at the front portion of the vehicle body 10 and directs the air intake port 22 in the forward direction of the vehicle body 10, while the air intake portion of the engine EG. The rear end portion is connected to the arranged air cleaner AC and is provided for implementation. For convenience of explanation, the left side of FIG. 1 is the front side of the intake duct, and the right side of the drawing is the rear side of the intake duct.

  An air circulation port 60 is formed at a required position of the air flow passage 58 in the duct body 30. A valve body 70 is provided on the downstream side of the air circulation port 60. The valve body 70 can be slid in the air circulation direction, and the side facing the air circulation port 60 bulges out in a substantially cone shape. In addition, a space 40 is defined outside the air flow passage 58 and spatially communicates with the air flow passage 58 via a communication port 42 established in the duct body 30 and functions as a resonance chamber. Further, on the outer side of the valve body 70, each of the communication ports 42 faces the inner side of the duct body 30, and the communication area R of the communication port 42 (see Equation 1 described later) as the valve body 70 slides. A shutter member 76 for adjusting the increase / decrease is provided.

  On the other hand, a compression spring (biasing member) 82 is disposed between the valve installation portion 46 provided in the duct main body 30 and the valve body 70, and the valve body 70 is always elastically biased toward the air circulation port 60 side. It is in a state. Then, the valve body 70 slides along the air flow direction due to the balance between the pressure of the air sucked by the rotation of the engine EG and the urging force of the compression spring 82, and the air flow at the air flow port 60. The area S and the communication area R at the communication port 42 are changed. According to such a configuration, when the engine EG is running at a low speed, the air circulation area S at the air circulation opening 60 is reduced and the communication area R that is the sum of the opening areas of the communication openings 42 is reduced, which is necessary for the engine EG. As a result, the engine noise generated from the engine EG can be reduced. Further, when the engine EG is rotating at a high speed, the air circulation area S at the air circulation opening 60 increases and the communication area R, which is the sum of the opening areas of the communication openings 42, increases, so that sufficient air can be taken into the engine EG. At the same time as allowing, the engine noise generated from the engine EG can be reduced.

  In other words, in the intake duct D of the present embodiment, the valve body 70 slides according to the rotational speed of the engine EG, thereby increasing or decreasing the air flow area S in the air flow port 60 and the communication area R of the communication port 42. Is configured to increase or decrease. In addition, the aspect of the increase / decrease change of the air circulation area S with respect to the slide movement of the valve body 70 may be continuous or intermittent. Similarly, the mode of increase / decrease change of the communication area R with respect to the slide movement of the valve body 70 may be continuous or intermittent.

  The duct body 30 includes a duct member 32 that is connected and fixed to the air cleaner AC, and an air intake member 34 that is attached to the front side of the duct member 32. The duct member 32 is a synthetic resin molding material made of high-density polyethylene or the like, and, as illustrated in FIGS. 1 and 4, two saddle-shaped halves 32A formed by assembling a plurality of molded parts. A cylindrical shape is formed by opposingly joining 32A, and the front portion has a larger diameter than the rear portion behind it. An installation opening 36 for the air intake member 34 is formed in the front end face on the front end face of the large-diameter front part, and an air delivery port 38 connected to the air cleaner AC is protruded. ing. In the large diameter portion described above, the inner diameter dimension of the air flow passage 58 is also set so that the valve installation portion 46 of the air intake member 34 installed through the installation opening 36 is accommodated inside. It has become.

  Further, a space 40 having a required volume, which has a donut shape surrounding the air flow passage 58, is defined on the outside of the air flow passage 58, and the large diameter portion has an inner / outer double structure. Presents. The air flow passage 58 and the space 40 are connected via a plurality of (four in the embodiment) communication ports 42 (42A, 42B, 42C, 42D) that are opened at a required interval in the circumferential direction of the duct body 30. The space 40 communicates spatially and, as will be described in detail later, the space 40 functions as a resonance chamber (resonator). In the embodiment, the case where the outer wall portion defining the space 40 is integrally formed with the duct member 32 is illustrated. However, the outer wall portion may be attached to the duct member 32 as a separate component.

  The air intake member 34 is a synthetic resin molding material made of high-density polyethylene or the like, and, as illustrated in FIG. 7, exhibits a so-called funnel shape in which the front air intake port 22 expands toward the tip. The air intake tube portion 44 and a valve installation portion 46 connected and fixed to the rear side of the air intake tube portion 44 are configured. The valve installation part 46 is set to an outer diameter dimension that allows the insertion into the duct member 32 through the installation opening 36 described above. As a result, the air intake member 34 inserts the valve installation portion 46 into the duct member 32, and extends the air intake cylinder portion 44 forward from the duct member 32 to the front side of the duct member 32. Mounted and fixed. And the rib 48 extended in the circumferential direction is protrudingly provided in the outer surface of the air intake member 34, and this rib 48 is made to contact | abut to the opening end surface of the installation opening part 36, with respect to the duct member 32 The air intake member 34 is positioned. The air intake member 34 is fixed to the duct member 32 by appropriate fixing means such as a screw (not shown).

  As illustrated in FIG. 2 and the like, the valve installation portion 46 has a front portion serving as a valve storage space 50 communicating with the air intake tube portion 44 described above, and a later-described valve body 70 is stored therein. On the rear side of 50, there are slide guide portions 52, 54 for supporting the valve body 70 so as to be slidable. A boundary portion between the air intake tube portion 44 and the valve installation portion 46, that is, a front end portion of the valve storage space 50 serves as an air circulation port 60, and a total of four outer wall portions corresponding to the valve storage space 50 are provided. A rectangular opening 56 is opened in the circumferential direction. As a result, an air flow passage 58 extending from the inside of the air intake tube portion 44 to the inside of the duct member 32 is defined via the air circulation port 60 and the respective openings 56 described above.

  The valve body 70 has an outer diameter size that can be installed in the valve storage space 50 described above, and has a substantially cone shape in which the front side facing the air circulation port 60 bulges. Is set to be substantially the same as or slightly smaller than the inner diameter of the air circulation port 60. A rod 72 inserted into the small-diameter slide guide 52 is disposed at the rear end of the valve body 70, and the large-diameter slide guide 54 is slid at the tip of the rod 72. The stopper 74 which contacts is fixed. Accordingly, the valve body 70 is allowed to slide in the range of the stroke H along the air flow direction in the valve storage space 50 because the rod 72 and the stopper 74 are in sliding contact with the respective sliding guide portions 52 and 54. Is done. In addition, the above-mentioned “cone shape” defined by the present application is a shape in which the outer diameter dimension gradually decreases toward the tip side, such as a conical shape, a truncated cone shape, an umbrella shape, etc. in addition to the bullet shape illustrated in each figure. It is premised on that it has a shape that can contain everything, and can suppress an increase in air flow resistance against the taken-in external air.

  Here, in the most advanced state of the valve body 70 in which the stopper 74 is in contact with the front end surface of the sliding guide portion 54, the front bulge portion of the valve body 70 leads to the air circulation port 60 as illustrated in FIG. 3. The air flow area S defined between the valve body 70 and the air flow port 60 is set to be minimum (S1) by appropriately entering. That is, when the valve body 70 is moved forward most, the outer surface of the valve body 70 is positioned at the edge of the air circulation port 60 with a slight gap, as schematically shown in FIG. A minimum necessary air flow area S (S1) that allows the intake of air required when the engine EG is running at a low speed is ensured.

  Moreover, since the front side of the valve body 70 bulges in a bullet shape, external air taken into the air intake member 34 via the air intake port 22 is transferred to the front side bulge surface of the valve body 70. At the same time as it collides, it is considered to smoothly spread radially along the bulging surface and to flow into the duct member 32 through the air circulation port 60 and each opening 56. Therefore, even if the air flow area S to be minimized is considerably smaller than the conventional air intake duct D illustrated in FIG. 13 and the like, the air required for the engine EG can be taken in. For this reason, since the air circulation area S can be reduced, the shielding performance against engine noise is improved, and engine noise radiated to the outside through the air intake port 22 is reduced.

  On the other hand, in the last retracted state of the valve body 70 in which the valve body 70 is in contact with the rear end surface of the valve storage space 50, the valve body 70 is almost completely removed from the air circulation port 60 as illustrated in FIG. Therefore, the air flow area S defined between the valve body 70 and the air flow port 60 is set to be the maximum (S2). When the valve body 70 is finally retracted, the stopper 74 is not removed from the sliding guide portion 54, and is necessary at the time of high rotation of the engine EG as schematically shown in FIG. 6 (b). The air circulation area S (S2) that allows the intake of air is secured.

  Moreover, since the valve body 70 bulges forward in a bullet shape, external air taken into the air intake member 34 via the air intake port 22 is transferred to the front bulge surface of the valve body 70. Simultaneously with the collision, it can be smoothly spread radially along the bulging surface and can flow into the duct member 32 through the air circulation port 60 and each opening 56. And since the attitude | position of the valve body 70 does not change when sliding to the back side, a lot of taken-in external air can be stably flowed into the large diameter part of the duct member 32, Air turbulence is prevented from occurring.

  Next, the shutter member 76 has a cylindrical shape set to an outer dimension slightly smaller than the inner diameter dimension of the duct main body 30, and a total of four support collars 78 extending radially from the outer peripheral surface of the valve body 70, The valve body 70 is integrally formed. When the valve body 70 attached to the valve installation portion 46 slides, the valve body 70 moves along the inner peripheral surface of the duct body 30 so as to face each of the communication ports 42 (42A, 42B, 42C, 42D). It has become. In addition, the shutter member 76 is formed with a notch 80 that matches one of the four first communication ports 42A described above. When the valve body 70 is in the most advanced state, the first communication port 42A has a notch. 80 are matched. Note that the air taken in from the air take-in cylinder portion 44 flows downstream through a gap between the inside of the shutter member 76 and the outside of the valve body 70. Further, when the valve body 70 is installed in the valve installation portion 46, each support collar 78 extends outward through each opening 56.

  Each of the communication ports 42 (42A, 42B, 42C, 42D) communicating the air flow path 58 and the space 40 is approximately 1 / of the stroke H of the valve body 70 as illustrated in FIGS. 3 is set in a circular shape set to a diameter K corresponding to 3, and each is located at an angular difference of 90 ° in the circumferential direction of the duct body 30 and is offset in the longitudinal direction of the duct body 30 as follows. It is located in the state. Specifically, the first communication port 42 </ b> A in which the aforementioned notch 80 is aligned and the second communication port 42 </ b> B adjacent to the first communication port 42 </ b> A are opened at the same position in the longitudinal direction of the duct body 30. . The third communication port 42C adjacent to the second communication port 42B is offset to the downstream side by a dimension corresponding to the diameter K with respect to the second communication port 42B. Further, the fourth communication port 42D adjacent to the third communication port 42C is positioned offset to the downstream side by a dimension corresponding to the diameter K with respect to the third communication port 42C.

  Accordingly, when the valve body 70 is in the most advanced state, the second communication port to the fourth communication ports 42B, 42C, and 42D are closed by the shutter member 76 as illustrated in FIG. Since the cutout portion 80 is aligned with the first communication port 42A, the air flow passage 58 and the space 40 communicate with each other only by the first communication port 42A. Then, as the valve body 70 slides from the most advanced state to the downstream side, as illustrated in FIGS. 8B to 8D, the second communication port 42B, the third communication port 42C, the fourth The communication port 42D is sequentially opened, and the communication area R between the air flow passage 58 and the space 40 is gradually increased.

  Specifically, when the valve body 70 is in the most advanced state, the communication area R between the air flow passage 58 and the space 40 is the opening area of the first communication port 42A. When the valve body 70 slides from the most advanced state to 1 / 3H, the opening of the second communication port 42B starts, the opening area gradually increases, and the air flow passage 58 at the time when the valve body 70 slides to 1 / 3H. The communication area R between the space 40 and the space 40 is the total opening area of the first communication port 42A and the second communication port 42B (FIG. 8B). Further, when the valve body 70 slides from 1 / 3H to 2 / 3H, the opening of the third communication port 42C starts, the opening area gradually increases, and the air flow at the time when the valve body 70 slides to 2 / 3H. The communication area R between the path 58 and the space 40 is the total opening area of the first communication port 42A, the second communication port 42B, and the third communication port 42C (FIG. 8C). Further, when the valve body 70 slides from 2 / 3H to the last retracted state, the opening of the fourth communication port 42D starts and the opening area gradually increases, and the air flow passage 58 and the space at the time of the last retracting are increased. The communication area R with 40 is the total opening area of the first communication port 42A, the second communication port 42B, the third communication port 42C, and the fourth communication port 42D (FIG. 8D).

  The urging force of the compression spring 82 described above is such that (1) the valve body 70 can be stopped and held at a position closest to the air circulation port 60 (most advanced state) when the engine EG is rotating at a low speed. The valve body 70 is set to a size that allows the valve body 70 to move away from the air circulation port 60 as the rotation of the engine EG increases. That is, the valve body 70 is slid back and forth so as to follow the rotational speed of the engine EG based on the balance between the air pressure taken in by the rotational drive of the engine EG and the urging force of the compression spring 82. The air flow area S at the air flow port 60 can be changed.

  As a result, when the engine EG is in a low rotation including the idling state, the urging force of the compression spring 82 wins over the pressure of the taken-in external air. The air flows into the port 60, the air flow area S of the air flow port 60 becomes the minimum S1, and the communication area R by the first communication port 42A becomes the minimum R1. Therefore, engine noise (combustion noise or the like) radiated to the outside through the air intake port 22 is suitably reduced.

  On the other hand, when the rotation of the engine EG is increased, the pressure of the external air taken in exceeds the urging force of the compression spring 82, so that the valve body 70 moves from the air circulation port 60 against the urging force of the compression spring 82. The air flow area S of the air flow port 60 is increased and the communication area R by the communication ports 42A, 42B, 42C, and 42D is increased. Moreover, since the pressure of the external air taken in increases as the engine speed increases, the amount of sliding movement of the valve body 70 increases and the air circulation area S and the communication area R increase.

  In the structure illustrated in the embodiment, the sliding movement amount of the valve body 70 and the accompanying increase / decrease amount of the air circulation area S of the air circulation port 60 are set to have a substantially proportional relationship. In addition, the first to fourth communication ports 42A, 42B, 42C, and 42D described above are formed in a circular shape and offset in the longitudinal direction of the duct body 30, so that the sliding movement amount of the valve body 70 is achieved. And the increase / decrease amount of the communication area R by the communication ports 42A, 42B, 42C, 42D are set to have a substantially proportional relationship.

  In the intake duct D of the embodiment, in the air flow passage 58, the cross-sectional area (air flow area) Sa at the point Pa in the air intake cylinder portion 44 and the break at the point Pb in the large diameter portion of the duct member 32. The area (air flow area) Sb is set to be substantially the same or larger. Further, the air flow area S (S2) at the air flow port 60 when the valve body 70 is finally retracted is set to be substantially the same as the above-described cross-sectional areas Sa and Sb. As a result, when the valve body 70 is finally retracted, the cross-sectional area of the air flow passage 58 becomes substantially constant at any position, and smooth distribution of the taken-in external air is realized.

  As described above, in the intake duct D of the present embodiment, the space 40 communicated with the air flow passage 58 through the first communication port to the fourth communication port 42A, 42B, 42C, 42D functions as a resonance chamber. It is characterized in that engine noise and intake noise in the air flow passage 58 can be reduced. Here, the resonance frequency of the resonator in the duct is calculated based on the following calculation formula, as is well known.

Each code in this calculation formula is as follows.
fr: resonance frequency (Hz)
C: Speed of sound 340 × 10 ³ (mm / s)
V: Internal volume (mm ³ ) of the resonance chamber (space 40)
G: Conductivity Le = t + (π / 2) a
R: Communication area of the communication port 42 (mm ² )
(In the case of the radius a (mm) of the communication port 42 and the number n: nπa ² )
t: Thickness of the duct body 30 (length of the communication port 42) (mm)

  According to the above calculation formula, it is understood that the setting condition of the communication area R which is the opening area of the communication port 42 and the setting condition of the internal volume V of the space 40 functioning as the resonance chamber are greatly related to the resonance frequency fr. it can. That is, when the internal volume V of the space 40 is constant, the resonance frequency fr becomes higher as the communication area R of the communication port 42 is set larger, and when the communication area R is constant, the internal volume V is set larger. It can be seen that the resonance frequency fr becomes lower.

  Here, in the intake duct D of the present embodiment, as described above, the internal volume V of the space 40 is constant, and the first communication port to the fourth communication port are moved by the movement of the shutter member 76 accompanying the sliding movement of the valve body 70. Since the opening areas of the communication ports 42A, 42B, 42C, and 42D change, the communication area R increases and decreases. That is, when the valve body 70 moves forward, the communication area R decreases, so the resonance frequency fr decreases. As the valve body 70 moves rearward, the communication area R increases, the resonance frequency fr. Gradually increases. In other words, it can be said that when the valve body 70 moves forward, it is effective in reducing low-frequency noise, and as the valve body 70 moves rearward, it is effective in reducing high-frequency noise.

  By the way, although the engine noise varies depending on the type of engine EG, the displacement, and the like, it is generally low frequency when the engine EG has a low rotation speed, and becomes higher as the engine EG has a higher rotation speed. For example, as shown in FIG. 10, as an example, the engine noise is about 80 Hz at 1,200 rpm, but increases by about 40 Hz every time the engine speed increases by 600 rpm. It is about 200 Hz at 3,000 rpm, and about 400 Hz at 6,000 rpm. Therefore, the intake duct D of the present embodiment can reduce low-frequency engine noise when the engine EG rotation speed is low, and reduces high-frequency engine noise as the engine EG rotation speed increases. Therefore, it is suitable for reducing engine noise whose frequency changes in accordance with the rotational speed of the engine EG in a wide range from low rotation to high rotation.

Next, the experimental results of the noise reduction effect of the engine in the intake duct D of the present embodiment configured as described above are compared with those of a straight pipe type intake duct Dn that does not have the space 40 functioning as a resonance chamber. To do. Here, the specifications of the intake duct used in the experiment are illustrated in FIG. 9 and are as follows.
1. Conventional straight pipe type intake duct Dn
-Duct total length L: 400mm
-Duct inner diameter d: 60 mm
2. Intake duct D of this embodiment
-Duct total length L: 400mm
・ Duct inner diameter (general part) d: 60mm
-Diameter M of space 40: 160 mm
-Space 40 length N: 90 mm
-Internal volume V of the space 40: 1.555 × 10 ⁶ mm ³
-Diameter K of each of the four communication ports 42A, 42B, 42C, 42D: 13 mm
・ Communication area R (opening area): Variable from 132.7 to 530.7 mm ²

  As can be seen from FIG. 10, it can be confirmed that the intake duct D having the above-described specifications exhibits an effect of reducing engine noise in substantially the entire engine speed as compared with the straight pipe type intake duct Dn. It was. In particular, there is an effect of reducing the sound pressure level of about 5 to 10 dB in the normal rotation range of about 2,000 to 2,500 rpm, and about 10 to 15 dB in the middle to high rotation range of 3,000 rpm or higher where engine noise increases. Therefore, the engine noise can be extremely effectively reduced in any rotation region. From this, the intake duct D of a present Example can reduce suitably the engine noise from which the frequency generate | occur | produced according to the rotation speed of the engine EG is different.

  As described above, the noise reduction characteristics can be changed by changing the setting of the internal volume V of the space 40 and the communication area R of the communication ports 42A, 42B, 42C, and 42D. Therefore, the noise reduction characteristic can be changed by changing the setting of the internal volume V and the communication area R according to the engine noise characteristic of the engine EG.

  Further, in the above-described embodiment, the first communication port to the fourth communication port 42A, 42B, 42C, 42D have a circular shape of the same size, and are offset and opened along the longitudinal direction of the duct member 32. The case where the slide movement amount of the valve body 70 and the increase / decrease amount of the communication area R by the communication ports 42A, 42B, 42C, 42D are set to have a substantially proportional relationship is illustrated. However, by changing the shape, size, number, position, etc. of the communication port 42, it is possible to set various modes of increase / decrease change of the communication area R with respect to the sliding movement of the valve body 70. For example, if the long hole slit-shaped communication port 42 is formed so as to extend in the sliding direction of the valve body 70, the communication area R can be linearly increased or decreased with respect to the sliding movement of the valve body 70. Further, if a plurality of circular communication ports 42 are formed at appropriate intervals in the sliding direction of the valve body 70, the communication area R can be intermittently increased or decreased with respect to the sliding movement of the valve body 70.

  According to the intake duct D of the present embodiment described above, the following effects can be obtained. First, since the valve body 70 slides according to the rotational speed of the engine EG, the air flow area S of the air flow passage 58 can be changed, and the communication area R between the air flow passage 58 and the space 40 can be changed. . Therefore, when the engine EG is running at a low speed, the air flow area S can be reduced and the communication area R can be reduced, so that the engine noise generated at the low speed can be suitably reduced. Further, when the engine EG is rotating at a high speed, the air flow area S can be increased and the communication area R can be increased to suitably reduce the engine noise generated at the time of high speed rotation. That is, since the air circulation area S and the communication area R can be varied according to the rotational speed of the engine EG, the intake of air necessary for the engine EG is allowed, and at the same time, the engine whose frequency varies with the rotational speed. Noise can be suitably reduced.

  Further, since the valve body 70 has a substantially cone shape that bulges toward the air circulation port 60 side, the air circulation resistance is greatly improved, and it is necessary to provide a bypass path 28 like the conventional intake duct D1 illustrated in FIG. Therefore, the manufacturing cost can be reduced, the assembly work can be facilitated, and the installation space can be reduced by downsizing. Therefore, since the air circulation area S at the time of low rotation can be reduced, the emission of the engine sound from the air intake port 22 at the time of low rotation can be effectively suppressed low, and a resonator having a large volume becomes unnecessary.

  When the valve body 70 slides along the air flow direction of the air flow passage 58, the posture does not change with respect to the flow of the taken-in external air, so the air flow flowing through the air flow passage 58 is changed. It is possible to suitably prevent the occurrence of disturbance. Further, since the slide movement of the valve body 70 is performed based on the balance between the pressure of the taken-in external air and the urging force of the compression spring 82, a separate valve movement mechanism or the like is not particularly required, and the whole is compact. And an increase in product cost is prevented. Further, since the amount of slide movement of the valve body 70 and the accompanying increase / decrease amount of the air flow area S of the air flow port 60 are set to have a substantially proportional relationship, the rotational speed and output of the engine EG are directly set. Thus, an ideal engine output characteristic can be obtained. Furthermore, since the sliding movement amount of the valve body 70 and the accompanying increase / decrease amount of the communication area R by the communication ports 42A, 42B, 42C, 42D are set to have a substantially proportional relationship, the engine EG The reduction efficiency of engine noise whose frequency changes according to the rotational speed can be effectively increased.

(Another embodiment)
FIG. 11 is a cross-sectional view showing an intake duct D according to another embodiment. In the intake duct D of this other embodiment, the valve body 70 is connected to a valve moving mechanism 90 that is driven based on the detected rotational speed of the engine EG, and slides in conjunction with the rotational speed of the engine EG. It is like that. The valve moving mechanism 90 includes, for example, a motor 92 provided in the valve installation portion 46, a ball screw 94 connected to the rotation shaft of the motor 92, and a ball attached to the valve body 70 and screwed into the ball screw 94. It comprises a guide 96 and a controller 98 that detects the rotational speed of the engine EG and controls the driving of the motor 92 based on this. Then, when the motor 92 rotates forward or backward, the ball guide 96 moves along the ball screw 94, so that the valve body 70 whose rotation in the circumferential direction is restricted slides. The motor 92 is fixed to the valve installation portion 46 without protruding from the valve installation portion 46 at all, and thus does not hinder the flow of the taken-in external air.

  According to such a configuration, it is possible to control the movement of the valve body 70 with high accuracy in accordance with the rotational speed of the engine EG, and the increase / decrease amount and the communication area of the air circulation area S associated with the rotational speed of the engine EG. It is possible to accurately control the amount of increase / decrease in R. Further, the sliding amount of the valve body 70 and the shutter member 76 with respect to the rotational speed of the engine EG can be changed to a mode other than the proportional relationship, and the engine noise reduction characteristic can be freely set. Therefore, even in the intake duct D according to another embodiment, the same effect as the intake duct D of the above-described embodiment is achieved.

  In the above-described embodiment and another embodiment, the duct member 32 that forms the main body of the duct body 30 is exemplified by a cylindrical shape that exhibits a true circle. However, the present invention is not limited thereto, and a cylindrical shape that exhibits an elliptical shape, It may be a rectangular tube having a rectangular shape.

  In the above-described embodiment and another embodiment, the case where the space 40 is defined as a single unit is illustrated. However, a type in which a plurality of spaces 40 having different internal volumes are defined may be used.

  Further, when mounting on a vehicle type having a different body shape and size, only the duct member 32 may be changed to another duct member having a different size and shape, and the air intake member 34 and the valve body 70 attached thereto. Can be used in common, and the cost reduction effect due to the common use of parts is further enhanced.

  Since the intake duct according to the present invention is mounted on an air intake portion of an engine and used for implementation, it can be widely implemented in various automobiles and other industrial machines equipped with the engine.

The top view which showed the intake duct which concerns on a suitable Example in the state which partially fractured | ruptured and abbreviate | omitted. FIG. 2 is a partial perspective view illustrating a main part of the intake duct illustrated in FIG. It is the III-III sectional view taken on the line of FIG. 1, Comprising: The state which minimized the air circulation area and the communication area with the valve body is shown. IV-IV sectional view taken on the line of FIG. Sectional drawing of the intake duct shown in the state which made the air distribution area and the communication area the maximum with the valve body. Explanatory drawing which showed schematically the minimum state and the maximum state of the air circulation area in an air flow path. The exploded perspective view of an air intake member, a valve body, and a compression spring. Explanatory drawing which showed that the communication area of an airflow path and space changes to increase / decrease by a shutter member moving with the movement of a valve body. Schematic which showed the form of each intake duct used for the experiment which confirms the noise reduction effect of the intake duct of an Example. The graph which showed the noise reduction performance of the intake duct of a present Example. Sectional drawing which showed the state which made the air distribution area and communication area the valve body with the air intake duct which concerns on another Example minimized. 1 is a side sectional view of a vehicle showing a front side portion of a vehicle body with an intake duct assembled thereto. Explanatory drawing which illustrated schematically the variable structure of the air circulation area in the conventional intake duct. Explanatory drawing which showed the problem of the air intake duct illustrated in FIG. Explanatory sectional drawing which showed the structure of the intake duct currently implemented. Explanatory drawing which showed another problem of the air intake duct illustrated in FIG.

Explanation of symbols

30 duct body, 40 space, 42 communication port, 46 valve installation part, 58 air flow passage,
60 air circulation port, 70 valve body, 76 shutter member,
82 compression spring (biasing member), 90 valve moving mechanism, EG engine, R communication area,
S Air distribution area

Claims (7)

The air flow area (S) of the air flow passage (58) connected to the air intake part of the engine (EG) and defined in the duct body (30) is determined according to the rotational speed of the engine (EG). In the intake duct that is changed by
An air circulation port (60) formed in a required portion of the air flow passageway (58), and
A valve body (70) disposed on the downstream side of the air circulation port (60) and capable of sliding movement in the air circulation direction, the side facing the air circulation port (60) bulging into a substantially cone shape. When,
It is defined outside the air flow passage (58) and spatially communicates with the air flow passage (58) via a communication port (42) established in the duct body (30), and functions as a resonance chamber. Space (40),
A shutter member that is provided outside the valve body (70), faces the communication port (42), and adjusts the communication area (R) of the communication port (42) to increase / decrease as the valve body (70) slides. (76)
The valve body (70) slides in accordance with the rotational speed of the engine (EG), thereby increasing or decreasing the air circulation area (S) in the air circulation port (60) and communicating with the communication port (42). An air intake duct configured to increase or decrease the area (R).   The valve body (70) is attached to a valve installation portion (46) provided in the duct body (30), and is slidable along the air flow direction of the air flow passage (58). The intake duct described. The valve body (70) is always elastically applied to the air circulation port (60) side by an urging member (82) disposed between the valve body (70) and the duct body (30). Arranged in a state
When the engine (EG) is rotating at low speed, the biasing force of the biasing member (82) is close to the air circulation port (60) side, and when the rotation of the engine is increased, the pressure of external air taken in is increased. The intake duct according to claim 1 or 2, wherein the intake duct is separated from the air circulation port (60) against the urging force of the urging member (82).   The urging force of the urging member (82) is large enough to stop and hold the valve body (70) at a position closest to the air circulation port (60) when the engine (EG) rotates at low speed. The intake duct according to claim 3, wherein the intake duct is set to a size that allows the valve body (70) to move away from the air circulation port (60) as the rotation of the engine (EG) increases.   The valve body (70) is connected to a valve moving mechanism (90) driven based on the detected rotational speed of the engine (EG), and slides in conjunction with the rotational speed of the engine (EG). The intake duct according to claim 1 or 2.   The sliding movement amount of the valve body (70) and the increase / decrease amount of the air circulation area (S) of the air circulation port (60) accompanying this are set so as to have a substantially proportional relationship. The intake duct according to any one of the above. The slide movement amount of the valve body (70) and the increase / decrease amount of the communication area (R) of the communication port (42) accompanying this are set so as to have a substantially proportional relationship. The intake duct described in 1.

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