JP2009264182A - Gas conduit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas conduit can effectively deaden or reduce flow sound caused by flow of gas by effectively using a narrow assembling space. <P>SOLUTION: The gas conduit 10 includes a lead-in tube 11 for leading in gas and a lead-out tube 12 for leading out the gas. The lead-in tube 11 and the lead-out tube 12 are coupled together by a muffler 13 having a hollow part for deadening or reducing the conduction sound of the gas. A hollow part of the muffler 13 is shaped into a flat form in which a maximum value of a vertical sectional area indicative of the sectional area of a section vertical to a parallel section is smaller than a parallel sectional area indicative of the sectional area of a section parallel to a lead-in side connection surface 13a or a lead-out side connection surface 13b, and is shaped into a fan shape with a center angle of approximately 90°. As a result, the gas conduit 10 can effectively deaden or reduce the flow sound of a desired frequency, and can utilize the narrow assembling space effectively. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a gas conduction pipe that conducts gas, and more particularly, to a gas conduction pipe that includes a silencer that reduces conduction noise that accompanies gas conduction.

  In general, when a gas is conducted through a pipe (duct), a conduction noise is generated or propagated along with the conduction of the gas, and this conduction noise is radiated from the open end of the pipe (duct). well known. Such a pipe body (duct) that conducts gas, that is, a gas conduction pipe, is widely used in various fields. Particularly, in a vehicle, a pipe body (duct) for introducing air into an engine or a vehicle interior. A pipe body (duct) for air-conditioning is provided. And in a vehicle, since these pipe bodies (ducts) are provided at positions close to the occupant, it is easy for the occupant to perceive conduction sound (noise) emitted from these pipe bodies (ducts). For this reason, in the case of using a gas conduction pipe, it is widely practiced to provide a silencer in order to reduce conduction noise (noise) generated with gas conduction.

  For example, Patent Document 1 below discloses an intake device provided with a resonator as a silencer. In this conventional intake device, an opening is formed in a peripheral wall of an intake duct that forms an intake passage, and a casing that constitutes a resonator is provided so as to cover the opening. As a result, the conduction sound (noise) generated by the intake air flowing through the intake duct is propagated from the opening into the casing and enlarged, thereby reducing the conduction sound (noise).

  Further, for example, Patent Document 2 below discloses a Helmholtz resonator for reducing sound caused by vibration of gas flowing inside a tubular body. This conventional resonator is provided with a communication pipe radius adjusting means for changing the inner diameter of the communication pipe for connecting to the pipe body in accordance with the ambient temperature, and can vibrate at a preset resonance frequency even if the ambient temperature changes. It absorbs the vibration of the gas that flows through the tube and reduces the sound.

Further, for example, Patent Document 3 below shows a duct of an air conditioner using a slit resonator. The duct of this conventional air conditioner includes an inflow tube, an outflow tube, and a case that connects the inflow tube and the outflow tube and functions as an expansion chamber. The inflow cylinder, the outflow cylinder, and the case constitute a slit resonator, and when gas flows from the inflow cylinder to the outflow cylinder in the case, a conduction sound (noise) is propagated into the case and expanded. ing. Thereby, noise of a specific frequency is muted or reduced.
JP 2004-285876 A JP-A-11-44266 JP 2006-335125 A

  By the way, in order to effectively mute or reduce the conduction noise (noise) generated by the gas flowing in the pipe body (duct), a method of increasing the capacity of the silencer is generally adopted. In other words, by adopting a silencer with a large capacity, the conduction sound (noise) propagating in the pipe (duct) can be expanded well, and as a result, the conduction sound (noise) is effective. Can be attenuated. Therefore, the conduction sound (noise) generated by the gas flowing in the pipe (duct) can be effectively silenced or reduced.

  However, in particular, in vehicles, in addition to the limited space in the engine room, in recent years, unitization of auxiliary equipment and the like assembled in the engine room has progressed, and gas conduction pipes such as intake ducts and air conditioning ducts have been developed. It is often assembled using a narrow space generated between these units. For this reason, it is difficult to secure a space for providing a large-capacity silencer (resonator). Therefore, it is desired that the gas conducting pipe has a function to effectively mute or reduce the conducting pipe (noise) flowing in the pipe body (duct) and can effectively use a limited space.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to effectively mute or reduce a conduction sound generated with gas conduction by effectively using a narrow assembly space. An object of the present invention is to provide a gas conduction pipe that can be used.

  The feature of the present invention is that the introduction pipe for introducing the gas, the lead-out pipe for leading out the introduced gas, and the conduction of the gas flowing from the lead-in pipe to the lead-out pipe by connecting the lead-in pipe and the lead-out pipe In the gas conduction pipe provided with a silencer that reduces conduction noise generated along with the silencer, the silencer has a hollow portion that communicates with the introduction pipe and the lead-out pipe. With respect to a parallel cross-sectional area representing a cross-sectional area including the hollow portion in a cross section parallel to the introduction side connection surface of the silencer to which the pipe is connected or the lead side connection surface of the silencer to which the lead pipe is connected The vertical cross-sectional area representing the cross-sectional area including the hollow portion in the cross-section perpendicular to the parallel cross-section is formed in a flat shape having the smallest vertical cross-sectional area and formed in a fan shape.

  According to this, the introduction pipe which introduces gas (for example, air etc.) and the lead-out pipe which derives gas can be connected to the silencer which has the hollow part formed in flat shape and fan shape. And the conduction | electrical_connection sound can be effectively reduced by passing the gas which conducts toward an derivation | leading-out pipe | tube through the flat-shaped and fan-shaped hollow part formed in the silencer. Here, the flat shape is a cross-sectional area including a hollow portion in a cross section parallel to the introduction side connection surface of the silencer to which the introduction pipe is connected or the lead-out side connection surface of the silencer to which the lead pipe is connected, that is, a parallel cross-sectional area. On the other hand, a cross-sectional area including a hollow portion in a cross section perpendicular to the parallel cross section, that is, a shape having a small maximum vertical cross-sectional area among vertical cross-sectional areas, in other words, a thin shape. The sector shape means a radius passing through both ends of an arc and a shape surrounded by the arc, and a center angle formed by two radii is 180 ° or less.

  Thus, by adopting a silencer having a thin fan-shaped hollow portion, when the conducted gas passes from the introduction pipe to the lead-out pipe, the generated conduction sound propagates into the hollow portion. . At this time, the vibration of the gas caused by the propagated conduction sound can be propagated from the center of the sector of the hollow portion toward the arc, for example. As a result, the propagation distance of the vibration of the gas caused by the conduction sound can be made substantially equal so that the vibration of the gas can resonate with the air present in the hollow space, in other words, the air that exists in the fan-shaped space. The conduction noise accompanying gas conduction can be effectively reduced. Moreover, by making the hollow portion into a flat shape, the thickness of the silencer can be made thin. As a result, the silencer can be arranged in a narrow space, and the overall length of the gas conduction pipe including the introduction pipe, the lead-out pipe and the silencer can be shortened, and the arrangement shape of the introduction pipe and the lead-out pipe (that is, the bent shape) Etc.) can be favorably secured. Therefore, even when the assembly space is small, this space can be used effectively.

  In this case, the ratio of the parallel sectional area of the hollow portion in the silencer to the maximum vertical sectional area of the hollow portion in the silencer may be, for example, 7 to 18. Moreover, it is good to set the center angle of the hollow part formed in the said fan shape within the range of 45 degrees or more and 180 degrees or less, for example.

  Thus, the hollow portion is shaped into a flat shape so that the ratio of the parallel sectional area of the hollow portion to the maximum vertical sectional area of the hollow portion in the silencer is, for example, 7 to 18, and the center of the hollow portion is For example, the lead-side connection surface and the lead-out side connection surface can be more appropriately resonated by forming the fan into a sector shape having an angle in a range of 45 ° to 180 °. Then, the flat shape of the hollow portion and the central angle of the sector can be set as appropriate, so that the resonance frequencies of the introduction side connection surface and the extraction side connection surface that resonate with the vibration of the gas caused by the conduction sound can be easily changed (adjusted). be able to. As a result, the conduction sound having a desired frequency can be selectively and appropriately reduced. Therefore, even in an installation environment of a gas conduction tube, for example, an installation environment where installation space is scarce, the shape of the hollow portion can be easily set in accordance with this installation environment, and the conduction sound can be silenced or reduced. Can do.

  In this case, the connection-side opening communicating with the hollow portion of the introduction tube and the connection-side opening communicating with the hollow portion of the lead-out tube may be opposed to each other. According to this, the gas introduced from the introduction pipe can be smoothly flowed to the outlet pipe through the hollow portion, and for example, pressure loss due to conduction can be greatly reduced.

  In this case, the introduction pipe and the lead-out pipe may be connected to the silencer in the vicinity of the center of the hollow portion formed in the fan shape. The center axis of the introduction pipe and the center axis of the outlet pipe are coaxially arranged, and the center axis of the hollow portion formed in the fan shape is coaxially arranged with the center axis of the introduction pipe and the center It may be located on the central axis of the lead-out axis. According to these, while it is possible to secure a longer propagation distance of the gas vibration caused by the conduction sound in the hollow portion, it is possible to more reliably propagate the gas vibration in one direction from the center of the sector toward the arc. it can. Therefore, since the vibration of the gas and the hollow portion, in other words, the air existing in the fan-shaped space can resonate with each other, it is possible to effectively reduce the conduction noise caused by the gas conduction. .

  Further, in this case, the connection side end surface facing the hollow portion of the introduction tube and the surface on the side where the introduction side connection surface forms the hollow portion are substantially flush with each other and the hollow portion of the lead-out tube It is preferable that the connection-side end surface facing and the surface on the side where the lead-out-side connection surface forms the hollow portion are substantially flush with each other. According to this, the distance in the facing direction between the connection-side end face of the introduction pipe and the connection-side end face of the lead-out pipe can be substantially matched with the thickness dimension of the hollow portion. Thereby, the conduction sound of gas can be efficiently propagated in the hollow part of a silencer, As a result, a conduction sound can be reduced favorably.

  Furthermore, in this case, the introduction pipe, the silencer, and the lead-out pipe may be integrally formed. Thereby, when a gas conduction pipe is formed from a resin material, for example, it can be easily and integrally formed by a blow molding method or the like. For this reason, the number of parts which comprise a gas conduction pipe can be reduced, and while favorable assembly property can be secured, molding cost can be reduced.

  Another feature of the present invention is that the introduction pipe of the gas conduction pipe described above conducts the outside air toward the silencer, and the lead-out pipe derives the outside air that has passed through the silencer toward the vehicle engine. In this way, the gas conduction pipe may be applied to the intake system of the vehicle. As a result, even in an environment where it is difficult to secure a sufficient assembly space, such as the engine room of a vehicle, it is very easy to assemble a gas conduction pipe that has a sufficient silencing or reduction effect by effectively using a narrow space. Can do.

  And, by applying a gas conduction pipe provided with a silencer having a flat and fan-shaped hollow part to the intake system of the vehicle, the vehicle is related to the conduction sound generated when the vehicle engine sucks outside air, that is, the intake sound. It is possible to effectively reduce a sound in the vicinity of about 80 Hz that is recognized as an unpleasant sound by a passenger who has boarded the vehicle (a so-called muffled sound).

  In this case, the silencer may form a part or all of other parts installed in the engine room of the vehicle. In this case, specifically, the silencer may, for example, form part or all of a battery tray that supports a battery mounted on the vehicle, and the silencer, for example, an engine of the vehicle. A part or all of the engine cover to be covered may be formed. According to these, it is possible to use a silencer in which components (for example, a battery tray, an engine cover, etc.) to be assembled in the engine room as separate components have been formed into a flat plate shape. As a result, the number of parts to be assembled in the engine room can be reduced, and it is not necessary to secure a separate space for arranging the silencer. Therefore, even in an environment where it is difficult to secure a sufficient assembling space, it is possible to construct a vehicle intake system very easily and to effectively use a narrow space.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. FIG. 1 schematically shows a gas conducting tube 10 according to an embodiment of the present invention. As shown in FIG. 1, the gas conduction pipe 10 connects the introduction pipe 11 for introducing gas from the outside, the lead-out pipe 12 for leading out the introduced gas, and the lead-in pipe 11 and the lead-out pipe 12. And a silencer 13 that silences or reduces the conduction sound (noise) generated with the conduction of the introduced gas.

  Here, the introduction pipe 11, the lead-out pipe 12 and the silencer 13 constituting the gas conduction pipe 10 are integrally formed by using a predetermined thermoplastic resin material (polypropylene or the like), for example, by a blow molding method or the like. Yes. In addition, regarding the forming material of the inlet tube 11, the outlet tube 12, and the silencer 13, it is not limited to the same material, A separate material can also be used as needed. Further, the forming material is not limited to the resin material, and other materials such as a metal thin plate may be employed.

  As shown in FIGS. 1 and 2, the introduction pipe 11 and the lead-out pipe 12 are formed in a substantially cylindrical shape having a predetermined inner diameter and a predetermined thickness, and are introduced from the introduction pipe 11 side through the silencer 13. Gas is conducted in the direction of the outlet tube 12. Further, as shown in FIGS. 1 and 2, the connection-side opening of the introduction pipe 11 to the silencer 13 and the connection-side opening of the outlet pipe 12 to the silencer 13 are in a mutually opposed state, and in this state, the silencer 13 is connected.

  As shown in FIGS. 1 and 2, the silencer 13 is formed in a fan shape having a central angle of approximately 90 degrees, and the lead-out connecting surface 13a to which the lead-in pipe 11 is connected and the lead-out pipe 12 are connected. It has a side connection surface 13b, and is formed into a flat fan shape having a thin space between the introduction side connection surface 13a and the lead-out side connection surface 13b, that is, a small thickness. Here, as shown in FIGS. 1 and 2, the introduction pipe 11 and the outlet pipe 12 are connected to the vicinity of the centers of the introduction-side connection surface 13 a and the outlet-side connection surface 13 b that form the silencer 13, respectively. More specifically, the introduction pipe 11 and the lead-out pipe 12 are positioned in the arc direction from the center of the fan-shaped lead-in connection surface 13a and the lead-out connection face 13b, and the outer peripheral surfaces of the lead-in pipe 11 and the lead-out pipe 12 have a fan-shaped radius. It connects so that two corresponding surfaces may be contacted. As shown in FIGS. 2 and 3, the silencer 13 includes an introduction pipe 11 and a lead-out pipe 12 in the interior thereof in order to mute or reduce conduction noise (noise) generated with gas conduction. The communicating hollow portion is formed by each wall surface (introduction side connection surface 13a and outflow side connection surface 13b) having a predetermined plate thickness (for example, about 5 mm).

  By the way, as mentioned above, the silencer 13 has a function of muting or reducing a conduction sound (noise) generated with the conduction of gas. In this function, a conduction sound (noise) generated in the introduction pipe 11 or the lead-out pipe 12 is turned into a hollow portion formed in a fan shape of the silencer 13 (hereinafter, the hollow portion formed in the fan shape is also referred to as an attenuation space). This is realized by attenuating the propagated conduction sound (noise), in other words, the vibration of the gas.

  More specifically, when the vibration of the gas propagates in the attenuation space formed in the silencer 13, the propagated vibration of the gas is a gas existing in the attenuation space formed in a fan shape (hereinafter, this gas is introduced into the space). It is transmitted in the direction of the arc from the center of the sector using the internal gas). At this time, the gas in the space resonates with the vibration of the gas having a specific vibration frequency based on the natural frequency determined by the shape of the damping space, that is, the sector, and is similar to the so-called dynamic damper. Can be damped. In the following description, the frequency at which the gas in the space resonates is referred to as the resonance frequency.

  In this way, in the case where the gas in the space is vibrated at the resonance frequency to reduce the vibration of the gas, in other words, the conduction sound (noise), the emitted conduction sound (noise) is reduced as much as possible in the attenuation space. By propagating equally over a long distance, the vibration of the gas can be damped more effectively. That is, when the distance of propagation of the vibration of the gas radiated in the attenuation space is short, the proportion of the vibration of the gas that attenuates is relatively small because the amount of gas in the space that resonates in the attenuation space is relatively small. The generated vibration of the gas may be reflected by the wall surface forming the attenuation space and return to the introduction pipe 11 and the lead-out pipe 12, for example. In this case, a conduction sound (noise) is emitted from the introduction pipe 11 and the lead-out pipe 12 due to the vibration of the gas that has been reflected back, and the conduction sound (noise) is silenced or reduced. May not be possible.

  In addition, when the vibrations of the gas propagating in the attenuation space and propagating over a long distance are mixed with the vibrations of the gas propagating over a short distance, the ratio of the vibration of the gas propagating over a long distance Depending on the difference from the vibration ratio, the frequency range of the conduction sound (noise) that is silenced or reduced by the silencer 13 may change. Specifically, due to the molding error of the silencer 13 and the difference in the radial direction of the vibration of the gas that may be different for each gas conducting tube 10, the proportion of the gas vibration that propagates over a long distance and the short distance propagation. The ratio of the gas vibration may be different for each gas conducting tube 10. For this reason, there is a possibility that the conduction sound (noise) cannot be effectively silenced or reduced even though the resonance frequency is adjusted (tuned) so that it can be silenced or reduced by the silencer 13.

  In view of such matters, the inventor of the present application makes the silencer 13, more specifically, the shape of the introduction-side connection surface 13a and the lead-out-side connection surface 13b into a fan shape, and the introduction-side connection surface 13a and the lead-out-side connection surface 13b. The introduction pipe 11 and the outlet pipe 12 are connected in the vicinity of the center. Thereby, the vibration of the gas radiated into the attenuation space from the introduction pipe 11 and the lead-out pipe 12 propagates by substantially the same distance from the center of the sector shape. Therefore, the resonance frequency can be easily adjusted (tuned) and the conduction sound (noise) can be appropriately silenced or reduced by appropriately setting and shaping the shape of the attenuation space that becomes a fan shape. become.

  Therefore, the present inventor conducted various experiments and determined the silencer 13 formed in a flat fan shape, more specifically, the shape of the attenuation space as a hollow portion. This will be specifically described below.

  First, in order to determine the flat shape of the attenuation space, the inventor of the present application defined the flat shape as follows. That is, the flat shape of the attenuation space has a cross-sectional area in a cross section parallel to the introduction side connection surface 13a or the lead-out side connection surface 13b, that is, a cross-sectional area including the hollow portion shown in FIG. 3), the cross-sectional area in a cross section perpendicular to the parallel cross-section, that is, the largest vertical cross-sectional area of the cross-sectional area including the hollow portion shown in FIG. Is called a small shape. Here, with respect to the maximum vertical cross-sectional area, for example, in FIG. 2, the cross-sectional area including the radius connecting the arc and the center of the fan-shaped connection surface 13a (or the lead-out connection surface 13b) formed in a fan shape. Maximum vertical cross-sectional area.

  According to this definition, when the maximum vertical cross-sectional area is larger than the parallel cross-sectional area, that is, the ratio of the parallel cross-sectional area to the maximum vertical cross-sectional area (hereinafter, this ratio is simply referred to as the cross-sectional area ratio) is “1”. The smaller the value, the thicker the attenuation space. Therefore, the flat shape with a small thickness in the facing direction of the introduction pipe 11 and the outlet pipe 12 is limited to the case where the cross-sectional area ratio is at least larger than “1”.

  And this inventor produces the various samples for evaluation from which cross-sectional area ratio of the silencer 13 (attenuation space) becomes larger than "1" as shown in FIG. 1, and the shape suitable for a flat fan shape investigated. Here, when investigating a shape suitable for a flat fan shape, various evaluation samples were evaluated using an experimental apparatus schematically shown in FIG. More specifically, a reference sound (white noise) is generated by continuously changing the frequency with respect to the opening end portion of the outlet tube 12 formed to have a predetermined length of various evaluation samples. Assemble the speakers. On the other hand, a sound collecting microphone that collects the radiated sound emitted after passing through the silencer 13 from the outlet tube 12 is disposed in the vicinity of the opening end portion of the introduction tube 11 formed to have a predetermined length set in advance. To do.

  Then, using this experimental apparatus, a white noise whose frequency is continuously changed is generated from a speaker provided in the outlet tube 12, and a radiated sound is collected from the opening end of the introduction tube 11 via the silencer 13. The ratio of the sound pressure level of the collected sound to the sound pressure level of white noise (hereinafter, this ratio is simply referred to as the sound pressure level ratio) was measured. In the measurement of the sound pressure level ratio, as a comparison object, the sound pressure level of the radiated sound is also obtained for a comparison sample without the silencer 13, that is, a straight tube comparison sample in which the introduction tube 11 and the extraction tube 12 are directly connected. The ratio was measured.

  FIG. 5 is an example of the measurement result described above, and schematically shows a change in the sound pressure level ratio with respect to a change in the frequency of white noise emitted from the speaker. In FIG. 5, the change in the sound pressure level ratio of the evaluation sample provided with the silencer 13 is indicated by a solid line, and the change in the sound pressure level ratio of a comparative sample not provided with the silencer 13 is indicated by a broken line. As apparent from FIG. 5, the sound pressure level ratio in the comparative sample indicated by the broken line is large with respect to the frequency change of the white noise, that is, the white noise is not reduced, whereas the evaluation sample indicated by the solid line It can be understood that the sound pressure level ratio is small, that is, white noise is reduced.

  Further, it can be understood that there is a white noise frequency at which the sound pressure level ratio is minimized when the white noise frequency is continuously changed in the evaluation sample. By the way, at the frequency at which the sound pressure level ratio is minimized, the white noise is further reduced, in other words, the air vibration accompanying the generation of the white noise is further attenuated. This is because white noise emitted from the speaker propagates in the attenuation space of the silencer 13 and the air in the space existing in the attenuation space resonates, so that the vibration of the air accompanying the generation of white noise is greatly attenuated. Means that That is, the frequency of the white noise at which the sound pressure level ratio is minimized means the resonance frequency of the air in the space existing in the attenuation space.

  Then, in order to determine the flat shape of the attenuation space in the silencer 13, the inventor of the present application investigated the relationship between the cross-sectional area ratio and the resonance frequency for various evaluation samples having different cross-sectional area ratios. As a result, the relationship shown in FIG. 6 was obtained. According to the relationship shown in FIG. 6, the resonance frequency becomes higher as the cross-sectional area ratio becomes smaller, and the resonance frequency becomes lower as the cross-sectional area ratio becomes larger. That is, as the thickness of the silencer 13 increases, the resonance frequency moves to the higher frequency side to effectively mute or reduce high frequency sound, and as the thickness decreases, the resonance frequency moves to the lower frequency side to lower the low frequency sound. It has a silencing characteristic that effectively silences or reduces noise.

  In addition, the inventor of the present application determines the shape of the attenuation space in the silencer 13 that maintains the relationship between the cross-sectional area ratio and the resonance frequency, that is, the fan shape, a) the central angle of the fan shape, and b) the fan shape. Radius, c) Attenuation space thickness (hereinafter referred to as slit width) is considered to be a parameter that affects the silencing characteristics, and an evaluation sample is prepared by appropriately changing each of the parameters a) to c), and the resonance frequency changes. investigated. Hereinafter, the change in the resonance frequency when each of the parameters (a) to (c) is changed will be described in detail.

B) Relationship between fan-shaped center angle and resonance frequency In order to investigate this relationship, the present inventor made evaluation samples having fan-shaped center angles of 45 °, 60 °, 90 °, and 180 ° as well as reference. A circular silencer was prepared as a reference sample and the resonance frequency was investigated. The result is shown in FIG. According to the relationship shown in FIG. 7, the resonance frequency becomes higher as the sector central angle becomes smaller, and the resonance frequency becomes lower as the sector central angle becomes larger. In other words, the attenuation space in the silencer 13 is such that the smaller the central angle, the higher the resonance frequency moves to the higher frequency side, and the higher frequency sound is effectively silenced or reduced. The larger the central angle, the more the resonant frequency moves to the lower frequency side. As a result, the low frequency sound is effectively silenced or reduced.

B) Relationship between sector radius and resonance frequency This relationship complements the relationship of the cross-sectional area ratio described above. That is, when the vertical sectional area (maximum vertical sectional area) is the same, the sectional area ratio increases as the sector radius increases, and the sectional area ratio decreases as the sector radius decreases. In order to investigate this relationship, the inventor of the present application produced evaluation samples having different fan-shaped radii (distance from the center to the arc) and investigated the resonance frequency. The result is shown in FIG. According to the relationship shown in FIG. 8, the resonance frequency is on the higher frequency side as the radius is smaller, and the resonance frequency is on the lower frequency side as the radius is larger. As described above, this corresponds to the tendency that the resonance frequency becomes higher as the cross-sectional area ratio becomes smaller, and the resonance frequency becomes lower as the cross-sectional area ratio becomes larger. That is, the attenuation space in the silencer 13 is such that the smaller the radius, the higher the resonance frequency moves to the higher frequency side, and the higher frequency sound is effectively silenced or reduced. The larger the radius, the more the resonance frequency moves to the lower frequency side. It has a silencing characteristic that effectively silences or reduces low frequency sound.

C) Relationship between slit width and resonance frequency This relationship complements the relationship of the cross-sectional area ratio described above. That is, when the parallel cross-sectional areas are the same, the cross-sectional area ratio decreases as the slit width increases, and the cross-sectional area ratio increases as the slit width decreases. In order to investigate this relationship, the inventor of the present application manufactured evaluation samples with different slit widths and investigated the resonance frequency. The result is shown in FIG. According to FIG. 9, the resonance frequency is on the higher frequency side as the slit width is larger, and the resonance frequency is on the lower frequency side as the slit width is smaller. As described above, this corresponds to the tendency that the resonance frequency becomes higher as the cross-sectional area ratio becomes smaller, and the resonance frequency becomes lower as the cross-sectional area ratio becomes larger. That is, the attenuation space in the silencer 13 is such that as the attenuation space is thicker, the resonance frequency moves to the higher frequency side to effectively mute or reduce high-frequency sound, and as the attenuation space is thinner, the resonance frequency is lower. The low frequency sound can be effectively silenced or reduced by moving to the side.

  Based on such a silencing characteristic, the shape of the attenuation space in the silencer 13 that forms the gas conduction tube 10 is generally a basic that reduces conduction noise (noise) associated with gas conduction that can be perceived by humans. The cross-sectional area ratio is set within a range of 7 to 18 in order to ensure the sound deadening characteristics. Furthermore, the center angle is set within a range of 45 ° to 180 ° in order to ensure a silencing characteristic for muting or reducing a specific frequency, particularly a sound in a low frequency range. Thus, by determining the shape of the attenuation space, about 70 Hz to 450 Hz, which is easily perceived as a conduction sound (noise) by humans among the frequencies of the conduction sound generated when gas is conducted through the gas conduction pipe 10. Can be selectively silenced or reduced in a low frequency range of about 70 Hz to 150 Hz or less.

  Further, by appropriately changing the cross-sectional area ratio (more specifically, sector radius and slit width) related to the flat shape of the attenuation space in the silencer 13 and the central angle related to the sector, noise reduction or reduction can be achieved. The frequency range can be selectively changed. Therefore, the silencing characteristic of the silencer 13 can be adjusted very easily. As described above, since the silencing characteristics can be adjusted very easily, the shape of the silencer 13 (attenuation space) can be changed in accordance with the environment where the gas conduction pipe 10 is installed, for example, the installation environment where the assembly space is scarce. it can.

  Here, the inventor of the present application also investigated the relationship between the size of the pipe diameters (hereinafter referred to as duct diameters) of the introduction pipe 11 and the outlet pipe 12 connected to the silencer 13 and the resonance frequency. In order to investigate this relationship, the inventors of the present application produced evaluation samples with different duct diameters and investigated the resonance frequency. In this investigation, in order to eliminate the influence that the attenuation space increases / decreases as the duct diameter changes, the distance between the outer peripheral surface of the introduction pipe 11 and the outlet pipe 12 and the fan-shaped arc-shaped peripheral surface of the silencer 13 , In other words, evaluation samples prepared so that the volumes in the attenuation space were equal were used. As a result, when the volumes in the attenuation space are equal, the resonance frequency is almost constant regardless of the size of the duct diameter. Therefore, in the gas conduction pipe 10, the duct diameter does not greatly affect the silencing characteristics.

  Thus, the gas conduction pipe 10 provided with the silencer 13 that can effectively mute or reduce the conduction sound (noise) associated with gas conduction is assembled in the engine room of a vehicle in which it is difficult to secure an assembly space. The vehicle intake pipe can be constructed. Hereinafter, the case where the gas conduction pipe 10 is applied to a vehicle will be described.

  FIG. 10 schematically shows a state in which the gas conduction pipe 10 is assembled to the engine 30 in the engine room 20 to constitute the intake pipe K of the vehicle. Here, in the gas conduction pipe 10 constituting the intake pipe K of the vehicle, a conduction sound having a frequency in the vicinity of 80 Hz that is easily perceived as an unpleasant conduction sound (a so-called humming sound) by the vehicle occupant is effectively reduced. Like that. For this reason, the sector shape of the silencer 13 is set to a cross-sectional area ratio of 14 to 18 based on the relationship shown in FIG. 6, and the central angle of the sector shape is set to 90 ° based on the relationship shown in FIG.

  The intake pipe K includes an intake duct 14, an air cleaner 15 and an air cleaner hose 16 in which a gas conduction pipe 10 is formed. In this case, the gas conduction tube 10 may be formed on the air cleaner hose 16 and implemented.

  The intake duct 14 conducts outside air (air) sucked by the engine 30, and the gas conduction pipe 10 is integrally formed at a substantially middle portion thereof. For this reason, in the gas conduction pipe 10 formed in the intake duct 14, the introduction pipe 11 conducts air toward the silencer 13, and the lead-out pipe 12 leads the air that has passed through the silencer 13 toward the engine 30. More specifically, it is led out toward the engine 30 via the air cleaner 15 and the air cleaner hose 16. Note that the intake port 14a of the intake duct 14 is disposed toward the front of the vehicle, and in order to reduce the flow resistance of the intake air, the outer shape of the general portion of the intake duct 14 (introduction pipe 11 and outlet pipe 12). It is formed to be expanded than the dimensions.

  The air cleaner 15 is connected to the intake duct 14, more specifically, to the outlet pipe 12 of the gas conduction pipe 10. The air cleaner 15 includes an air cleaner element 15a inside and filters the air introduced by the intake duct 14. As for the arrangement of the air cleaner 15, it is also possible to provide it on the upstream side of the silencer 13 of the gas conduction pipe 10, that is, on the introduction pipe 11 side of the gas conduction pipe 10 formed in the intake duct 14.

  The air cleaner hose 16 is provided between the air cleaner 15 and the engine 30. The air cleaner hose 16 supplies the air filtered by the air cleaner element 15 a of the air cleaner 15 to the engine 30 via the throttle body 31.

  Next, the operation of the intake pipe K configured using the gas conduction pipe 10 will be described. When an ignition switch (not shown) of the vehicle is turned on, the engine 30 sucks air through the intake pipe K according to the opening of the throttle body 31 and starts operation. At this time, the engine 30 sequentially repeats each operation process (suction, compression, explosion, and discharge), and therefore air vibrations, that is, pulsations are generated in the entire intake pipe K. Therefore, the vibration frequency of the generated pulsation changes according to the rotational speed of the engine 30. When the pulsation thus generated reaches the intake duct 14, the pulsation is attenuated by the silencer 13, so that the sound pressure level of air conduction sound (so-called intake noise) radiated from the intake duct 14 is reduced. Is done.

  That is, the pulsation that has reached the silencer 13 propagates in the attenuation space formed in a fan shape with a central angle of 90 ° formed in the silencer 13 and resonates with the air in the space as described above. Attenuates. At this time, if the cross-sectional area ratio in the fan shape of the silencer 13 is set to 14 to 18, a pulsation having a vibration frequency in the vicinity of about 80 Hz among vibration frequencies that change in accordance with the rotational speed of the engine 30 is effective. Can be attenuated. Thereby, it is possible to effectively reduce the unpleasant conduction sound generated in the intake pipe K when the vehicle is traveling, that is, the sound pressure level of the intake noise.

  Incidentally, the silencer 13 of the gas conduction pipe 10 constituting the intake pipe K forms a part of the battery tray 41 for supporting the battery 40 mounted on the vehicle, as shown in FIGS. 10 and 11, for example. It is supposed to be. That is, the silencer 13 constituting the intake pipe K is configured so that the plate-like plane portion coincides with the horizontal direction of the vehicle, in other words, the introduction pipe 11 and the outlet pipe 12 coincide with the vertical direction of the vehicle. Assembled. Thereby, conventionally, the battery tray 41 formed by using the silencer 13 can be disposed in an assembling space secured for a battery tray necessary for assembling the battery 40 to the vehicle. Therefore, even in the engine room of a vehicle in which it is difficult to secure a sufficient assembling space, it is not necessary to secure a separate assembling space for arranging the silencer 13, and a narrow space can be used very effectively. it can.

  As can be understood from the above description, according to the above embodiment, the gas conduction pipe 10 can be formed by using the silencer 13 having a small thickness by making the attenuation space as the hollow portion flat. . And by setting the cross-sectional area ratio including the attenuation space formed in the fan-shaped silencer 13 within the range of 7 to 18 and setting the central angle within the range of 45 ° to 180 °, the gas conduction is achieved. The accompanying conduction sound can be effectively silenced or reduced. Moreover, by making the silencer 13 into a thin flat shape, it can be easily assembled even in a narrow assembly space.

  For this reason, by applying the gas conduction pipe 10 to the intake pipe K of the vehicle, the gas conduction pipe 10 can be easily assembled even in an engine room where it is difficult to secure an installation space. That is, in the conventional intake pipe, in order to reduce intake noise, it is necessary to use a substantially rectangular parallelepiped resonator, and in this embodiment, the flat and fan-shaped silencer 13 is used. it can. Thereby, the intake pipe K can be assembled | attached effectively using the narrow assembly space in an engine room.

  Further, by making the silencer 13 into a fan shape with a thin flat shape, for example, it is possible to ensure a wide arrangement interval between the silencer 13 and the air cleaner 15 as compared with a conventional intake pipe. Thereby, the operator can assemble the silencer 13 and the air cleaner 15 in a state in which the work space is sufficiently secured. Therefore, workability can be greatly improved.

  Further, when the gas conduction pipe 10 is applied to a vehicle, the center angle is set to 90 ° and the cross-sectional area ratio is set to 14 to 17 with respect to the shape of the attenuation space as the hollow portion. It is possible to effectively mute or reduce nearby intake noise. Therefore, it is possible to ensure easy assembling into a narrow space such as an engine room of a vehicle and to ensure good sound deadening characteristics.

  Further, the intake pipe K can be configured by arranging the connection side opening of the introduction pipe 11 to the silencer 13 and the connection side opening of the outlet pipe 12. Thereby, the flow resistance (pressure loss) when air is conducted from the intake duct 14 toward the air cleaner 15 and the air cleaner hose 16 can be significantly reduced. Therefore, the function originally required for the intake pipe K of efficiently supplying air to the engine 30 can be sufficiently exhibited.

  The implementation of the present invention is not limited to the above-described embodiment, and can be implemented by various modifications.

  For example, in the above-described embodiment, the introduction pipe 11 and the lead-out pipe 12 are connected to each other in the fan-shaped arc direction from the center of the lead-in connection face 13a and the lead-out connection face 13b of the silencer 13. In this case, as shown in FIG. 12, the introduction pipe 11 and the lead-out pipe are arranged so that the centers of the lead-in connection face 13a and the lead-out connection face 13b are located on the center axis of the lead-in pipe 11 and the lead-out pipe 12 that are opposed to each other. 12 can be connected.

  Moreover, in the said embodiment, it implemented so that the introduction | transduction pipe | tube 11, the derivation | leading-out pipe | tube 12, and the silencer 13 could be shape | molded integrally, and the gas conduction pipe | tube 10 was formed. However, it is also possible to form the introduction pipe 11, the lead-out pipe 12, and the silencer 13 separately, and assemble them integrally.

  Moreover, in the said embodiment, it implemented by applying the gas conduction pipe | tube 10 to the intake pipe K of a vehicle. However, for example, it can be applied to an air conditioning duct of a vehicle. Further, for example, the gas conduction pipe 10 can be applied to an exhaust duct or a ventilation duct of a building. Also in this case, since the silencer 13 of the gas conduction pipe 10 can be formed into a flat fan shape, for example, it can be embedded in a wall or the like to form an exhaust duct or a ventilation duct. Therefore, it is possible to mute or reduce the conduction sound that accompanies the gas conduction without deteriorating the aesthetic appearance, which is preferable.

  Moreover, in the said embodiment, it implemented so that the silencer 13 of the gas conduction pipe | tube 10 applied to the intake pipe of a vehicle may form a part or all of the battery tray 41. FIG. However, as schematically shown in FIG. 13, it is also possible to form a part or the whole of the engine cover 50 that can secure an assembly space relatively easily in the engine room. Even in this case, similarly to the above-described embodiment, it is possible to effectively use a narrow space and to mute or reduce a conduction sound generated due to gas conduction.

  Further, in the above-described embodiment, the axes of the introduction pipe 11 and the outlet pipe 12 that form the gas conduction pipe 10 are orthogonal to the introduction-side connection surface 13 a or the outlet-side connection surface 13 b of the silencer 13. Carried out. In this case, for example, the introduction pipe 11 and the lead-out pipe 12 are connected to the introduction-side connection surface 13a or the lead-out-side connection surface 13b so that each axis has a predetermined angle due to restrictions on vehicle mounting. Is also possible. In this case, since interference with other devices arranged in the engine room can be easily eliminated, a narrow space can be used more effectively.

It is a schematic perspective view which shows the gas conduction pipe | tube which concerns on embodiment of this invention. It is sectional drawing of the silencer (hollow part) in a cross section parallel to the introduction side connection surface or derivation side connection surface of the silencer which comprises the gas conduction pipe | tube of FIG. It is sectional drawing of the silencer (hollow part) in a cross section perpendicular | vertical to the cross section parallel to the introduction side connection surface or derivation | leading-out connection surface of the silencer which comprises the gas conduction pipe | tube of FIG. It is a figure for demonstrating the experimental apparatus for measuring a sound pressure level ratio. It is a graph which shows the change of the sound pressure level ratio with respect to the frequency change of the reference sound in an evaluation sample and a comparison sample. It is a graph which shows the relationship between a cross-sectional area ratio and a resonant frequency. It is a graph which shows the relationship between the center angle of a sector and resonance frequency. It is a graph which shows the relationship between a sector-shaped radius and a resonant frequency. It is a graph which shows the relationship between the slit width formed by the introduction side connection surface and the derivation side connection surface, and the resonance frequency. It is the schematic which shows the state which applied the gas conduction pipe | tube of FIG. 1 to the intake system of a vehicle. It is a figure for demonstrating the state in which the silencer of the gas conduction pipe | tube in FIG. 10 formed a part of battery tray. According to a modification of the present invention, there is provided a gas conduction pipe in which the introduction pipe and the lead-out pipe are connected so that the centers of the fan-shaped introduction-side connection face and the lead-out-side connection face are located on the central axis of the lead-in pipe and the lead-out pipe. It is a figure for demonstrating. It is a figure for demonstrating the state which concerns on the modification of this invention and the silencer of the gas conduction pipe formed a part of engine cover.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Gas conduction pipe | tube, 11 ... Introducing pipe, 12 ... Deriving pipe, 13 ... Silencer, 13a ... Introducing connection surface, 13b ... Deriving connecting surface, 14 ... Intake duct, 15 ... Air cleaner, 16 ... Air cleaner hose, 20 ... Engine room, 30 ... Engine, 31 ... Throttle body, 40 ... Battery, 41 ... Battery tray, 50 ... Engine cover

Claims (12)

Conduction that occurs as the gas flows from the introduction pipe to the lead-out pipe by connecting the lead-in pipe and the lead-out pipe to the lead-in pipe that introduces the gas, the lead-out pipe that leads out the introduced gas In a gas conduction pipe with a silencer that reduces sound,
The silencer has a hollow portion communicating with the introduction pipe and the outlet pipe,
The hollow portion represents a cross-sectional area including the hollow portion in a cross section parallel to an introduction side connection surface of the silencer to which the introduction pipe is connected or a lead-out side connection surface of the silencer to which the lead-out pipe is connected. The maximum vertical cross-sectional area of the vertical cross-sectional area representing the cross-sectional area including the hollow portion in the cross section perpendicular to the parallel cross-section with respect to the parallel cross-sectional area is formed in a flat shape with a small shape, and is formed in a fan shape. Characteristic gas conduit. In the gas conduction pipe according to claim 1,
A gas conduction pipe, wherein a ratio of the parallel cross-sectional area of the hollow portion in the silencer to the maximum vertical cross-sectional area of the hollow portion in the silencer is 7 to 18. In the gas conduction pipe according to claim 1,
A gas conduction pipe characterized in that a central angle of the hollow portion formed in the sector shape is set within a range of 45 ° or more and 180 ° or less. In the gas conduction pipe according to claim 1,
A gas conduction pipe characterized in that a connection side opening communicating with the hollow part of the introduction pipe and a connection side opening communicating with the hollow part of the outlet pipe face each other. In the gas conduction pipe according to claim 1,
A gas conduction pipe characterized in that the introduction pipe and the lead-out pipe are connected to the silencer in the vicinity of the center of the hollow portion formed in the fan shape. In the gas conduction pipe according to claim 5,
The central axis of the introduction pipe and the central axis of the outlet pipe are coaxially arranged, and the center of the hollow portion formed in the fan shape is coaxially arranged with the central axis of the inlet pipe and the outlet A gas conducting tube characterized by being positioned on the central axis of the shaft. In the gas conduction pipe according to claim 1,
The connection-side end surface facing the hollow portion of the introduction pipe and the surface on the side where the introduction-side connection surface forms the hollow portion are substantially flush,
The gas conduction pipe according to claim 1, wherein a connection-side end face of the lead-out pipe facing the hollow portion and a face of the lead-out-side connection face forming the hollow portion are substantially flush with each other. In the gas conduction pipe according to claim 1,
A gas conduction pipe, wherein the introduction pipe, the lead-out pipe, and the silencer are integrally formed. In the gas conduction pipe according to claim 1,
The introduction pipe conducts outside air toward the silencer,
The gas lead-out pipe, wherein the lead-out pipe guides outside air that has passed through the silencer toward a vehicle engine. In the gas conduction pipe according to claim 9,
The silencer
A gas conduction pipe which forms a part or all of other parts installed in an engine room of a vehicle. In the gas conduction pipe according to claim 10,
The silencer
A gas conduction pipe that forms part or all of a battery tray that supports a battery mounted on a vehicle. In the gas conduction pipe according to claim 10,
The silencer
A gas conduction pipe that forms part or all of an engine cover that covers the engine of the vehicle.

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