JPH0577575U - Silencer - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to muffle three frequency components in two resonance chambers, and to muffle extremely low frequencies without enlarging each resonance chamber. A first resonance chamber 5 and a second resonance chamber 6 which are partitioned by a partition wall 4 in the axial direction of the pipe 2 are formed in a resonance box 1 to which the pipe 2 is attached. And the second resonance chamber 6 and the first hole 3 provided in the pipe 2 are communicated with each other through the first resonance pipe 7, and the pipe 2 is provided with the second hole 8 and The hole 8 is communicated with the second resonance chamber 6 through the second resonance tube 9, and when the frequency of the sound of the gas flowing through the pipe 2 is extremely low, the opening of the second resonance tube 9 is closed, When the frequency of the sound of the gas flowing through 2 is higher than that in the above case, the closing means 11 for opening the opening of the second resonance tube 9 is provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a silencer that reduces the intake noise and exhaust noise of a specific frequency by using the resonance principle.

[0002]

[Prior Art]

 A resonance type silencer is known as a technique for reducing intake and exhaust noises in an intake system and an exhaust system of an internal combustion engine. As an example of this resonance type silencer, for example, Japanese Utility Model Publication No. 6-41663 is known.

In the silencer disclosed in the above publication, the inside of a resonance box through which a pipe is penetrated is divided into two by a flange to form a resonance chamber. Each of the divided resonance chambers is communicated with a resonance tube, and the resonance tube is also communicated with a pipe penetrating the resonance box. In such a muffler, since two resonance chambers are formed, it is possible to muffle two frequency components and enhance the function of reducing intake noise.

[0004]

[Problems to be solved by the device]

 However, the device disclosed in Japanese Utility Model Laid-Open No. 64-41663 described above still has a problem to be solved. (1) In order to further enhance the muffling function of the muffler, it is necessary to target the muffling of the three frequency components. However, when muffling the three frequency components, the three common chambers are Will be needed. Forming three independent resonance chambers complicates the structure of the resonance box and enlarges the device.

(2) When the number of resonance chambers is two while keeping the total volume of the resonance chambers constant, the volume of each resonance chamber becomes small, and the silencing effect in the cryogenic region becomes insufficient. Therefore, even if the volume of the partitioned resonance chamber is small, it is desirable to enhance the silencing effect in the extremely low frequency range.

(3) As a method for silencing the low frequency side without changing the volume of the resonance chamber, it is conceivable to lengthen the resonance tube, but in this case, the opening of the resonance tube is inevitable. A part of it will come close to the wall of the resonance chamber, and a sufficient silencing effect cannot be obtained. In other words, with this structure, the degree of freedom in designing the resonance chamber and the resonance tube is small, and the optimum silencing effect cannot be obtained.

The present invention focuses on the above problems, and provides a silencer capable of silencing three frequency components in two resonance chambers and capable of silencing extremely low frequencies without enlarging each resonance chamber. The purpose is to provide.

[0008]

[Means for Solving the Problems]

 A muffler according to the present invention for this purpose is configured as follows. A first resonance chamber and a second resonance chamber partitioned by a partition wall in the axial direction of the pipe are formed in a resonance box to which the pipe is attached, and the first resonance chamber and the second resonance chamber are formed. , The first hole provided in the pipe is made to communicate with each other through the first resonance pipe, the second hole is provided in the pipe, and the second hole is provided through the second resonance pipe. When communicating with the second resonance chamber, when the sound frequency of the gas flowing through the pipe is extremely low, the opening of the second resonance tube is closed, and the sound frequency of the gas flowing through the pipe is higher than that in the above case. In this case, the second resonance tube is provided with closing means for opening the opening.

[0009]

[Action]

 In the silencer configured in this manner, the second resonance tube is closed by the closing means in the extremely low sound range. Therefore, only the first hole of the pipe is opened to the first resonance chamber and the second resonance chamber through the first resonance pipe, and the volume of the resonance chamber where the first hole is opened. Is the sum of the volume of the first resonance chamber and the volume of the second resonance chamber. Further, in this case, the entire length of the first resonance tube functions as a silencing element. Therefore, the expansion of the volume of the resonance chamber, which is a silencing element, achieves silencing in the extremely low frequency range.

When the frequency of the sound of the gas flowing through the pipe becomes high, the lid of the closing means separates from the opening of the second resonance tube, and the second resonance tube is opened to the second resonance chamber. In this state, both the first resonance tube and the second resonance tube function as muffling elements. Therefore, the first resonance chamber and the second resonance chamber exhibit independent silencing effects, and low sound is achieved in the first resonance chamber and high sound is achieved in the second resonance chamber.

[0011]

【Example】

 A preferred embodiment of a silencer according to the present invention will be described below with reference to the drawings.

FIG. 1 to FIG. 6 show an embodiment of the present invention, and particularly show the case of application as an intake resonator for reducing intake noise of an automobile engine. In FIG. 1, reference numeral 1 indicates a rectangular resonance box. A pipe 2 having a circular cross section passes through the resonance box 1. A first hole 3 opening in the resonance box 1 is provided in the middle of the pipe 2 located in the resonance box 1. The sectional area of the first hole 3 is S ₁ .

A partition wall 4 is provided in a portion of the resonance box 1 located on the first hole 3. The resonance box 1 has a first resonance chamber 5 and a second resonance chamber 6 defined by a partition wall 4. The volume of the first resonance chamber 5 is set to V ₁ and the volume of the second resonance chamber 6 is set to V ₂ . The first resonance chamber 5 and the second resonance chamber 6 communicate with each other through a first resonance tube 7 that communicates with the first hole 3. The first resonance tube 7 is attached to the outer peripheral surface of the pipe 2 so as to cover the first hole 3. That is, the first hole 3 communicates with the first resonance chamber 5 through one of the first resonance tubes 7 and communicates with the second resonance chamber 6 through the other of the first resonance tubes 7. ing.

The total length of the first resonance tube 7 is set to L. In the first resonance tube 7, the length from the first hole 3 to the opening end on the first resonance chamber side is set to L _1, and the opening from the first hole 3 to the second resonance chamber 6 side is set. The length to the edge is set to L ₂ .

The pipe 2 is provided with a second hole 8 which opens to the second resonance chamber 6. The cross-sectional area of the second hole 8 is S ₂ . A second resonance tube 9 extending in a direction perpendicular to the axial direction of the pipe 2 is connected to the second hole 8. The length of the second resonance tube 9 is L ₃ .

The closing means 11 is disposed on the second resonance chamber 6 side. The closing means 11 includes a lid 12, a connecting member 13, and an actuator 14. The lid 12 is arranged in the second resonance chamber 6 so as to face the opening 9 a of the second resonance tube 9. The lid 12 is connected to one of the connecting members 13 penetrating the side surface of the resonance box 1. The other side of the connecting member 13 is connected to the actuator 14.

The actuator 14 is operated based on a signal from an engine control computer (not shown). The actuator 14 closes the opening 9a of the second resonance tube 9 with the cover 12 when the vibration frequency of the intake air flowing through the pipe 2 is extremely low at about 190 Hz. Further, the actuator 14 separates the lid body 12 from the opening of the second resonance tube 9 when the vibration frequency of the intake air flowing through the pipe 2 is a low sound of about 250 Hz or a high sound of about 330 Hz. .

Next, the operation of the above silencer will be described. When the vibration frequency of the intake air flowing through the pipe 2 is an extremely low sound of about 190 Hz, the opening 9a of the second resonance tube 9 is closed by the lid 12 of the closing means 11. In this state, as shown in FIG. 2, the first hole 3 provided in the pipe 2 functions as a muffling element, and the first hole 3 passes through the first resonance tube 7 and the first resonance chamber 7. 5 and the second resonance chamber 6 are opened. Therefore, the entire length L of the first resonance tube 7 functions as a silencing element. Moreover, the volume V of the resonance chamber which functions as a silencing element, becomes a volume V ₁ of the first resonance chamber 5 the sum of the volume V ₂ of the second resonance chamber 6.

Formula 1 shows a formula for calculating the frequency f _{1 at which} the sound can be muted in FIG. Here, V is the volume of the resonance chamber, L is the total length of the first resonance tube, S ₁ is the cross-sectional area of the first hole, and C is the speed of sound.

[0020]

[Equation 1]

FIG. 5 shows changes in the sound pressure level when the opening 9 a of the second resonance tube 9 is covered with the lid 12. As shown in FIG. 5, when the vibration frequency of the intake air flowing through the pipe 2 is 190 Hz, the sound pressure level sharply decreases, and the extremely low sound deadening effect is exhibited.

When the sound of the intake air flowing through the pipe 2 becomes higher than that in the case of FIG. 5, the actuator 12 separates the lid 12 from the opening 9 a of the second resonance tube 9. 3 and 4 show the muffling effect in this state. Of these, FIG. 3 shows the silencing effect of the first resonance chamber 5.

As shown in FIG. 3, on the first resonance chamber 5 side, the length L ₁ of the first resonance tube 7 and the volume V _{1 of} the first resonance chamber 5 function as a muffling element. Formula 2 shows a formula for calculating the frequency f _{2 at which} the sound can be muted in FIG.

[0024]

[Equation 2]

FIG. 6 shows changes in the sound pressure level when the opening 9 a of the second resonance tube 9 is opened. As shown in FIG. 6, when the vibration frequency of the intake air flowing through the pipe 2 is 250 Hz, the sound pressure level sharply decreases, and the low sound deadening effect is exhibited.

FIG. 4 shows the action of the second resonance chamber 6 when the opening of the second resonance tube 9 is open. As shown in FIG. 4, in the second resonance chamber 6, the length L ₂ of the first resonance tube 7, the volume V _{2 of} the second resonance chamber 6, and the length of the second resonance tube 9 are set. The length L ₃ and the cross-sectional area S ₂ of the second hole 8 function as a silencing element. Formula 3 shows a formula for calculating the frequency f _{3 at which} the sound can be muted in FIG.

[0027]

[Equation 3]

As shown in FIG. 6, when the vibration frequency of the intake air flowing through the pipe 2 is 330 Hz, the sound pressure level decreases and the high-pitched sound deadening effect is exerted. In this way, the opening 9a of the second resonance tube 9 is closed by the lid 12, and the lid 12 is separated from the opening 9a of the second resonance tube 9 so that 190 Hz, 250 Hz, and 330 Hz are set. The intake noise at one frequency is reduced.

In the present embodiment, an example in which the silencer is used as an intake resonator for reducing intake noise has been shown, but it goes without saying that it can be used as a silencer for reducing exhaust noise.

[0030]

[Effect of the device]

 According to the present invention, the following effects can be obtained.

(1) By the two resonance chambers formed in the resonance box, it is possible to reduce intake sound or exhaust sound for three frequencies. Therefore, it is not necessary to increase the number of resonance chambers by one, and the structure of the resonance box can be simplified.

(2) Since the sum of the volumes of the first resonance chamber and the second resonance chamber functions as a muffling element when the opening of the second resonance tube is closed by the closing means, the partition wall Even if the volume of each resonance chamber demarcated by is small, it is possible to reduce the suction and exhaust noise in the extremely low frequency range.

(3) Since the length of the resonance tube is not increased to reduce the suction and exhaust noise in the extremely low frequency range, it is not necessary to consider the mechanical interference of the resonance tube, and the degree of freedom in design is increased. Can be increased.

[Brief description of drawings]

FIG. 1 is a perspective view of a silencer according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a silencing effect in a state where the opening of the second resonance tube in FIG. 1 is covered with a lid.

FIG. 3 is a schematic diagram showing a silencing effect of the first resonance chamber in a state where the opening of the second resonance tube of FIG. 1 is opened.

FIG. 4 is a schematic diagram showing a silencing effect of the second resonance chamber in a state where the opening of the second resonance tube of FIG. 1 is opened.

5 is a characteristic diagram showing the relationship between the vibration frequency and the sound pressure level of the intake air flowing through the pipe in the state of FIG.

FIG. 6 is a characteristic diagram showing the relationship between the vibration frequency and the sound pressure level of the intake air flowing through the pipe in the states of FIGS. 3 and 4.

[Explanation of symbols]

 1 Resonance Box 2 Pipe 3 First Hole 4 Partition Wall 5 First Resonance Chamber 6 Second Resonance Chamber 7 First Resonance Tube 8 Second Hole 9 Second Resonance Tube 11 Closing Means 12 Lid

Claims (1)

[Scope of utility model registration request] 1. A resonance box to which a pipe is attached is formed with a first resonance chamber and a second resonance chamber which are partitioned by a partition wall in the axial direction of the pipe, and the first resonance chamber and the second resonance chamber are formed. The second resonance chamber and the first hole formed in the pipe are communicated with each other through the first resonance pipe, the pipe is provided with a second hole, and the second hole is formed into the second resonance pipe. Through the second resonance chamber, and when the frequency of the sound of the gas flowing through the pipe is extremely low, the opening of the second resonance tube is closed, and the frequency of the sound of the gas flowing through the pipe is A silencer provided with a closing means for opening the opening of the second resonance tube when the height is higher than the case.