Vehicular air intake apparatus

A Helmholtz resonator communicates with an interior of an intake passage, which is configured to draw intake air to a combustion chamber of an engine. The Helmholtz resonator has a volume chamber and a communication pipe. The volume chamber forms a resonance chamber. The communication pipe communicates the volume chamber with the intake passage. The communication pipe includes an acoustic stack, which is configured to cause a temperature gradient by utilizing an acoustic energy.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on reference Japanese Patent Application No. 2013-208998 filed on Oct. 4, 2013, the disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a vehicular air intake apparatus configured to draw intake air to a combustion chamber of an engine. More specifically, the present disclosure may relate to a configuration to cool intake air by utilizing a thermal acoustic effect (thermal acoustic phenomenon).

BACKGROUND

A background art will be described with reference toFIGS. 5, 6A, and 6B. As shown inFIG. 5, a thermal acoustic effect is caused by a sound wave. Specifically, a sound wave causes adiabatic compression of air and adiabatic expansion of air to generate acoustic energy, thereby to radiate heat on a compression side and to absorb heat on an expansion side. More specifically, an acoustic stack is employed to utilize a sound wave to cause adiabatic compression of air and adiabatic expansion of air thereby to cause a temperature gradient by utilizing the thermal acoustic effect. The acoustic stack causes difference in temperature at both ends due to heat absorption and heat radiation.

For example, Patent Document 1 discloses a configuration to cool intake air, which flows through the intake passage101, by utilizing acoustic energy in an intake passage101. More specifically, the configuration of Patent Document 1 cools intake air by utilizing sound wave energy caused by pulsation in intake air.

It is noted that, the configuration of Patent Document 1 may cause pressure loss in intake air and/or noise.

Publication of unexamined Japanese patent application No. 2007-270619

SUMMARY

It is an object of the present disclosure to produce a vehicular air intake apparatus configured to cool intake air in an intake passage by utilizing acoustic energy generated in the intake passage, with less pressure loss in intake air.

Patent Document 1 teaches a configuration to equip an acoustic stack in an intermediate portion in the intake passage101to cool intake air, which passes through the intake passage101. It is noted that, the configuration of Patent Document 1 is to cause intake air to pass through the acoustic stack directly. Therefore, the acoustic stack of Patent Document 1 causes a large impedance in intake air. Thus, the acoustic stack of Patent Document 1 causes a large pressure loss in intake air in the intake passage101.

In the intake passage101, pulsation in intake air and/or the like may cause air column resonance to result in occurrence of undesirable sound. When air column resonance in a low-pitched sound region occurs in the intake passage101, the air column resonance may travel as thick sound through an interior of a vehicle, since low-pitched sound is apt to travel easily. Consequently, air column resonance may cause noise in the interior of the vehicle. In consideration of this, as shown inFIG. 6A, a resonator102may be equipped in an intermediate portion of the intake passage101to reduce air column resonance in the intake passage101.

The resonator102includes a volume chamber103and a communication pipe104. The volume chamber103forms a resonance chamber. The communication pipe104communicates the volume chamber103with the intake passage101. It is noted that, in the resonator102, the diameter of the communication pipe104is set at a relatively large value in order to draw acoustic energy (sound wave of a noise reduction object), which is generated in the intake passage101, into the volume chamber103, and to enhance silencing effect of the resonator102. In this case, flow of intake air, which passes through the intake passage101, may be disturbed at a connection (branch portion) between the intake passage101and the communication pipe104. Consequently, pressure loss may arise in intake air inside the intake passage101.

The resonator102is configured to reduce sound by causing resonance. The resonator102is configured to reduce noise at a resonant frequency. As shown by the solid line β inFIG. 6B, the resonator102has a silencing characteristic, which has a peak around the resonant frequency. It is further noted that, as shown by the solid line γ inFIG. 6B, the resonator102may enhance noise, contrary to noise reduction, in frequency regions around the resonant frequency (peak frequency). Therefore, the resonator102may increase noise in the frequency regions around the resonant frequency.

According to an aspect of the present disclosure, a vehicular air intake apparatus is for an intake passage, which is configured to draw intake air to a combustion chamber of an engine. The vehicular air intake apparatus comprises a Helmholtz resonator communicating with an interior of the intake passage. The Helmholtz resonator has a volume chamber and a communication pipe. The volume chamber forms a resonance chamber. The communication pipe communicates the volume chamber with the intake passage. The communication pipe includes an acoustic stack, which is configured to cause a temperature gradient with an acoustic energy.

DETAILED DESCRIPTION

Embodiment

As follows, present disclosure will be described with reference to drawings.

First Embodiment

A first embodiment of the present disclosure will be described with reference toFIGS. 1A and 1B. A vehicular air intake apparatus includes an intake passage1, which draws intake air to a combustion chamber of an engine. The intake passage1includes an air intake duct, an intake manifold, and an intake port. The air intake duct is equipped with an air cleaner, a throttle valve, and/or the like. The intake manifold distributes air drawn through the air intake duct1into cylinders of the engine. The intake port is formed in a cylinder head of the engine.

A Helmholtz resonator2is equipped to an intermediate portion of the intake passage1. The Helmholtz resonator2may be equipped at, for example, an intermediate portion of the air intake duct. The Helmholtz resonator2is configured to muffle a sound wave at a target frequency. The sound wave may be caused by, of example, air column resonance in a low-pitched sound region caused by, for example, pulsation of intake air. The Helmholtz resonator2may be one or may be two or more. In a case where two or more resonators2are equipped, target frequencies (silence frequencies) of the resonators2may be the same or may be different from each other.

The resonator2includes a volume chamber3and a communication pipe4. The volume chamber3forms a resonance chamber internally. The communication pipe4communicates the interior of the volume chamber3with the intake passage1. In the present example, the volume chamber3and the communication pipe4may be formed of resin for weight reduction and cost reduction. It is noted that, the material of the volume chamber3and the communication pipe4is not limited to resin and may be arbitrary selected from various materials.

An acoustic stack5is equipped in the communication pipe4. The acoustic stack5is configured to cause a temperature gradient with acoustic energy. The acoustic stack5includes multiple small tubes (capillaries). The multiple small tubes communicate the interior of the intake passage1with the volume chamber3. The small tubes may be, for example, in a form of pipes, in a form of a laminated object formed by stacking wire nets, and/or in a form of continued bubbles. The configuration of the small tubes is not limited to the examples and may employ various forms.

The acoustic stack5may be formed of, for example, resin similarly to the communication pipe4. More specifically, for example, the acoustic stack5is formed of resin integrally with the communication pipe4in order to enhance mountability to another component. The material and/or the mounting configuration of the acoustic stack5are not limited to those of the examples. The acoustic stack5may be formed of a metallic material and/or a ceramic material and may be affixed to an interior of the communication pipe4. A material having a high thermal conductivity may be employed as the material of the acoustic stack5.

First Effect of First Embodiment

As described above, according to the present first embodiment, the acoustic stack5is equipped inside the communication pipe4of the resonator2. Intake air drawn through the intake passage1toward the engine does not pass through the acoustic stack5directly. In this way, the present configuration enables to restrict the acoustic stack5from increasing pressure loss in intake air. The acoustic stack5, which is located in the communication pipe4, cools intake air with acoustic energy generated in the intake passage1. The acoustic energy may be sound wave energy caused by pulsation and/or the like. More specifically, the acoustic stack5absorbs heat on the side of the intake passage1and radiates heat on the side of the volume chamber3, thereby to cool intake air, which passes through the intake passage1.

The present configuration according to the present first embodiment employs a simple configuration equipping the acoustic stack5in the communication pipe4of the resonator2. Therefore, the present configuration enables to cool intake air, which flows through the intake passage1, without causing significant pressure loss in intake air. The present configuration enables the acoustic stack5to cool intake air by using the acoustic energy, thereby to enhance a filling rate of intake air into the combustion chamber of the engine. Thus, the present configuration enables to enhance engine power and to reduce fuel consumption.

Second Effect of First Embodiment

As described above, the vehicular air intake apparatus according to the first embodiment includes the acoustic stack5located in the communication pipe4of the resonator2. The present configuration inhibits intake air from entering into the communication pipe4through the opening of the communication pipe4on the side of intake air. That is, the communication pipe4hardly exerts effect on intake air.

Therefore, intake air, which flows through the intake passage1, is hardly disrupted at a connection (branch portion) with the communication pipe4. Thus, the present configuration enables effectively to reduce pressure loss in intake air.

Third Effect of First Embodiment

As described above, the vehicular air intake apparatus according to the first embodiment includes the acoustic stack5located in the communication pipe4of the resonator2. The present configuration of the acoustic stack5divides the interior of the communication pipe4into small passages. Therefore, the interior of the communication pipe4is apt to be exerted with influence of viscosity of air. The interior of the communication pipe4is apt to be exerted with influence of viscosity of air, thereby to restrict the characteristic of the resonator2from being in a shape of an acute peak at the resonant frequency. In addition, as shown by the solid line α inFIG. 1B, silencing effect arises widely in a frequency range around the resonant frequency. Therefore, the present configuration may solve a concern of increase in noise at frequency regions around the resonant frequency, dissimilarly to a conventional configuration.

Second Embodiment

A second embodiment of the present disclosure will be described with reference toFIG. 2. According to the present second embodiment, the acoustic stack5is formed with multiple small tubes, and the small tubes are small in diameter on the side of the intake passage1. More specifically, according to the second embodiment, a microscopic tube stack5ais equipped to the acoustic stack5on the side of the intake passage1. The microscopic pipe stack5aincludes small diameter tubes. That is, according to the present second embodiment, an average aperture ratio of air passage holes (intake-side air passage holes) of the acoustic stack5at the end on the side of the intake passage1is set smaller than an average aperture ratio of air passage holes (chamber-side air passage holes) of the acoustic stack5on the side of the volume chamber3.

Effect of Second Embodiment

As described above, the microscopic tube stack5ais equipped in the acoustic stack5on the side of the intake passage1. Thus, the present configuration enables to enhance a heat absorption effect of the acoustic stack5on the side of the intake passage1. Therefore, the present configuration enables further to enhance cooling effect of intake air, which passes through the intake passage1.

Third Embodiment

A third embodiment of the present disclosure will be described with reference toFIG. 3. According to a third embodiment of the present disclosure, the resonator2has radiator fins3b. The radiator fins3bare equipped to an outer surface of a vessel member3aof the volume chamber3. The vessel member3ais in contact with the communication pipe4.

Effect of Third Embodiment

As described above, the acoustic stack5radiates heat on the side of the volume chamber3. The radiator fins3bequipped on the vessel member3aof the volume chamber3, which is in contact with the communication pipe4. Therefore, the radiator fins3benables to increase a quantity of heat dissipation on the side of the volume chamber3in the acoustic stack5, thereby to enhance an thermal acoustic effect. That is, the present configuration enables the acoustic stack5further to enhance cooling effect of intake air.

Fourth Embodiment

A fourth embodiment of the present disclosure will be described with reference toFIG. 4. The resonator2according to the present fourth embodiment includes the vessel member (first vessel member)3a, which is in contact with the communication pipe4. The vessel member3apartially defines the volume chamber3. The resonator2according to the present fourth embodiment further includes a second vessel member (other vessel member), which partially defines the volume chamber3in addition to the vessel member3a. The vessel member3ais formed of a material higher in thermal conductivity than a material of the second vessel member. Specifically, the vessel member3a, which is in contact with the communication pipe4, is formed of a material, which has a high thermal conductivity, such as aluminum. The other vessel member (second vessel member), which forms the volume chamber3, is formed of a material, which has a conductivity relatively lower than the conductivity of aluminum. The other vessel member (second vessel member), which partially forms the volume chamber3, may be formed of, for example, resin, as exemplified in the first embodiment. The vessel member3amay be entirely formed of a material having a high thermal conductivity.

Effect of Fourth Embodiment

As described above, the acoustic stack5radiates heat on the side of the volume chamber3. Therefore, the vessel member3aof the volume chamber3, which is in contact with the communication pipe4, is formed of a material having a high thermal conductivity, such as aluminum. Therefore, similarly to the third embodiment, the present configuration enables to enhance a quantity of heat dissipation of the acoustic stack5on the side of the volume chamber3. Thus, the present configuration enables to enhance a thermal acoustic effect. That is, the present configuration enables the acoustic stack5further to enhance cooling effect of intake air.

INDUSTRIAL APPLICATION

In the above-described embodiments, the resonator2, which has the acoustic stack5, is equipped to the air intake duct. The application of the resonator2is not limited to the above-described example. The resonator2may be equipped to, for example, the intake passage1at an arbitrary intermediate location. The resonator2may be equipped at, for example, an air cleaner, a surge tank of an intake manifold, and/or the like.

The drawings of the present disclosure exemplify the configuration in which the acoustic stack is accommodated in the entire region of the communication pipe of the resonator. It is noted that, the configuration of the acoustic stack and the communication pipe is not limited to the above-described example. The acoustic stack may be accommodated in, for example, a part of the communication pipe of the resonator. The configuration of the acoustic stack may be determined arbitrarily.

The above-described disclosure exemplifies the Helmholtz resonator. It is noted that, the acoustic stack may be accommodated in a silencer (quarter wave tube), which is not equipped with the volume chamber. In this case, the mounting position of the acoustic stack may be desirably close to a closed end of the quarter wave tube. It is further noted that, the mounting position of the acoustic stack is not limited to the position close to the closed end and may be determined arbitrarily.

According to the present disclosure, the vehicular air intake apparatus includes an acoustic stack equipped to the communication pipe of the resonator. The acoustic stack is configured to cool intake air by utilizing acoustic energy in the intake passage. The acoustic stack is located in the communication pipe of the resonator. Therefore, dissimilarly to a conventional configuration, intake air, which passes through the intake passage, does not pass through the acoustic stack directly. Therefore, the acoustic stack does no increase pressure loss in intake air, dissimilarly to a conventional configuration. In addition, the acoustic stack is located in the communication pipe to utilize acoustic energy, which is generated in the intake passage, thereby to cool intake air, which passes through the intake passage. Thus, the vehicular air intake apparatus according to the present disclosure employs a simple configuration equipping the acoustic stack in the communication pipe of the resonator. Therefore, the present configuration enables to cool intake air, which flows through the intake passage, without causing significant pressure loss in intake air.

The vehicular air intake apparatus according to the present disclosure includes the acoustic stack located in the communication pipe of the resonator. The present configuration enables to restrict intake air from flowing into the communication pipe through the intake air opening side of the communication pipe. Therefore, the present configuration facilitates intake air to flow through the intake passage with less influence of the communication pipe. Therefore, intake air, which flows through the intake passage, is hardly disrupted at the connection (branch portion) with the communication pipe. Thus, the present configuration enables effectively to reduce pressure loss in intake air.

The vehicular air intake apparatus according to the present disclosure includes the acoustic stack located in the communication pipe of the resonator. The present configuration of the acoustic stack divides the interior of the communication pipe into small passages. Therefore, the interior of the communication pipe is apt to be exerted with influence of viscosity of air. As the interior of the communication pipe is apt to be exerted with influence of viscosity of air, the characteristic of the resonator is restricted from being in an acute peak form around the resonant frequency. Thus, the present configuration causes a silencing effect widely in a frequency range around the resonant frequency. Therefore, the present configuration may reduce a concern of increase in noise at frequency regions around the resonant frequency, dissimilarly to a conventional configuration.