JP2008169781A - Exhaust muffling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain wide muffling effect, without reducing the muffling effect, without increasing the device volume, in a resonator type exhaust muffling device. <P>SOLUTION: This exhaust muffling device has a resonator case 5 defining a resonator chamber 5A communicated with an exhaust passage 3 by a first communicating hole 13, and a directional control valve 23 operating in a switching system by pressure of exhaust gas flowing in the exhaust passage 3. The effective length of the resonator chamber 5A is changed by switching operation of the directional control valve 23. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an exhaust silencer device, and more particularly, to a resonator type (branch type) exhaust silencer device used in an exhaust system of an automobile engine.

  A resonator type device is known as an exhaust silencer device used in an exhaust system of an automobile engine. The resonator-type exhaust silencer device silences a resonance frequency determined by the cavity length (tube length) of the resonator chamber.

On the other hand, since the frequency of the radiated sound of the exhaust system of an automobile engine varies depending on the engine speed, a plurality of cavities with different cavity lengths are used to reduce all radiated sound of different frequencies in the engine exhaust system. Some are provided with a resonance device (for example, Patent Documents 1 and 2), and another resonance device is provided with another resonance device having a different cavity length (for example, Patent Document 3).
JP 2004-156535 A JP 2005-226465 A JP 2005-23915 A

  By providing a plurality of resonant devices with different cavity lengths, the radiated sound of different frequencies can be reduced. However, the device volume is increased, the weight is increased, and it is configured as an in-vehicle device that is mounted on the engine exhaust system. There is a limit.

  A resonator device provided with another resonator device having a different cavity length in one resonator device is not bulky, but the cavity volume of the resonator device in which another resonator device is placed in the cavity is reduced, and radiation is reduced. Sound reduction effect is reduced.

  The present invention has been made to solve the above-described problems, and provides a resonator type exhaust silencer device that can be expected to have a broad silence effect without increasing the device volume and without reducing the silence effect. The purpose is that.

  An exhaust silencer device according to the present invention includes a resonator case that defines a resonator chamber that communicates with an exhaust passage through a communication hole, and a switching valve that performs switching operation according to the pressure of exhaust gas flowing through the exhaust passage. The length varies depending on the switching operation of the switching valve.

  An exhaust silencer device according to the present invention includes a resonator case that is provided outside an exhaust pipe and defines a resonator chamber that communicates with an exhaust passage formed by the exhaust pipe by a first communication hole provided in the exhaust pipe, and the exhaust passage. A switching valve that operates according to the pressure of the exhaust gas flowing through the first and second resonator chambers, wherein the resonator chamber is divided into a first resonator chamber and a second resonator chamber by an internal partition, and the first resonator chamber is separated from the first resonator chamber. The communication hole communicates with the exhaust passage, the first resonator chamber and the second resonator chamber communicate with each other by a second communication hole provided in the internal partition, and the second communication hole is formed by the second communication hole. It is opened and closed by a switching valve.

  More preferably, in the exhaust silencer device according to the present invention, the first resonator chamber and the second resonator chamber have different cavity lengths, and the second resonator chamber is open to the exhaust pipe. The communication valve communicates with the exhaust passage through three communication holes, and the switching valve opens and closes the second communication hole and the third communication hole in an opposite opening / closing relationship.

  More preferably, the exhaust silencer device according to the present invention receives a pressure of exhaust gas flowing through the exhaust passage and receives the pressure of the switching valve in a direction to close the second communication hole, and the second communication hole. Spring means for urging the switching valve in the direction of opening the switching valve, the switching valve until the driving force by the exhaust gas pressure acting on the pressure receiving plate overcomes the spring force by the spring means. When the communication hole is opened and the driving force by the exhaust gas pressure acting on the pressure receiving plate overcomes the spring force by the spring means, the second communication hole is closed.

  According to the exhaust silencer according to the present invention, since the effective length of the resonator chamber is changed by the switching operation of the switching valve, it is possible to effectively silence the radiated sound having different frequencies without requiring a plurality of individual resonance devices. can do.

  Hereinafter, an embodiment of an exhaust silencer device according to the present invention will be described with reference to FIGS.

  The exhaust silencer device of the present embodiment has a resonator case 5 attached to the outside of the exhaust pipe 1. The resonator case 5 is not narrow along a longitudinal direction of the exhaust pipe 1 (exhaust gas flow direction of the exhaust passage 3) in a resonator chamber (cavity) 5A separated from the exhaust passage 3 by the exhaust pipe 1 by the exhaust pipe 1. It is defined as a cavity. Here, it is assumed that the exhaust gas flows from the right end 3A to the left end 3B of the exhaust passage 3 as seen in FIGS.

  An internal partition wall 7 is fixedly mounted in the resonator case 5. The internal partition wall 7 divides the resonator chamber 5 into two resonator chambers, that is, a first resonator chamber 9 and a second resonator chamber 11 on the upstream side and the downstream side of the exhaust gas flow in the exhaust passage 3. ing.

  The first resonator chamber 9 communicates with the exhaust passage 3 through a first communication hole 13 provided in the exhaust pipe 1 on one end side. The first resonator chamber 9 and the second resonator chamber 11 communicate with each other through a second communication hole 15 opened in the internal partition wall 7. The second resonator chamber 11 communicates with the exhaust passage 3 at one end side through a third communication hole 17 opened in the exhaust pipe 1.

  The opening area of the first communication hole 13, the second communication hole 15, and the third communication hole 17 may be 15 to 20% or more of the cross-sectional area of the exhaust passage 3 so that sound waves can enter and exit.

  As one feature of the present embodiment, the cavity length of the first resonator chamber 9 (the length from the opening position of the first communication hole 13 to the internal partition wall 7) and the cavity length of the second resonator chamber 11 are described. The length from the opening position of the third communication hole 17 to the end wall 5B of the resonator case 5 is different from each other.

  In the resonator chamber 5A, a switching valve 21 is rotatably provided by a pivot 19. The switching valve 21 is constituted by a plate-shaped valve body, and includes a first switching position (see FIG. 1) for opening the second communication hole 15 and closing the third communication hole 17, and a second communication hole. The second switching position (see FIG. 2) that closes 15 and opens the third communication hole 17 can be rotated, and is biased toward the first switching position by the torsion spring 29, so that the second The communication hole 15 and the third communication hole 17 are opened and closed in a contradictory opening / closing relationship.

  As described above, the torsion spring 29 urges the switching valve 21 counterclockwise, that is, urges the switching valve 21 in a direction to open the second communication hole 15 as viewed in FIG. 4.

  The switching valve 21 is integrally provided with a pressure receiving plate 23 by a narrow bridge portion 25. The bridge portion 25 extends into the exhaust passage 3 through a slit hole 27 formed in the exhaust pipe 1, and the pressure receiving plate 23 on the distal end side of the bridge portion 25 is located in the exhaust passage 3. The pressure of the exhaust gas flowing through is received in the clockwise direction as seen in FIG. Thus, the pressure receiving plate 23 receives the pressure of the exhaust gas flowing through the exhaust passage 3 and drives the switching valve 21 in a direction to close the second communication hole 15.

  Thereby, the switching valve 21 opens the second communication hole 15 and closes the third communication hole 17 until the driving force by the exhaust gas pressure acting on the pressure receiving plate 23 overcomes the spring force by the torsion spring 29. When the driving force due to the exhaust gas pressure acting on the pressure receiving plate 23 overcomes the spring force due to the torsion spring 29, the second communication hole 15 is closed and the third communication hole 17 is opened. To the switching position.

  The pressure of the exhaust gas flowing through the exhaust passage 3 has a correlation with the engine speed, and is lower as the engine speed is lower.

  As a result, during idle operation to low speed operation, the switching valve 21 is positioned at the first switching position, the second communication hole 15 is opened, and the third communication hole 17 is closed. As a result, during idle operation to low speed operation, the exhaust silencing device is in the first state, as shown in FIG. 1, and the effective cavity length of the exhaust silencing device is the first resonator chamber. 9 cavity length and the cavity length of the second resonator chamber 11 are added together (for example, L = 150 mm), and it is effective to mute frequency sound which is a problem during idling to low / medium speed operation. To be done.

  On the other hand, at the time of medium to high speed operation, the switching valve 21 is located at the second switching position, the second communication hole 15 is closed, and the third communication hole 17 is opened. As a result, during middle to high speed operation, the exhaust silencing device is in the second state, as shown in FIG. 2, and the effective cavity length of the exhaust silencing device is that of the first resonator chamber 9. The cavity length (for example, L = 100 mm) and the cavity length (for example, L = 50 mm) of the second resonator chamber 11 are individually present, and the muffler of the frequency sound that becomes a problem during medium to high speed operation is present. Done effectively.

  The order component when the engine speed is low is, for example, in the case of 600 to 3000 revolutions per minute, sound waves of 20 Hz to 100 Hz in the first order, 40 Hz to 200 Hz in the second order, 60 Hz to 300 Hz in the second order, As vibration radiated sound or transmitted sound, it is generated from a portion where noise such as a muffler shell or an end plate is likely to be generated.

  In this case, if the original pulsation is attenuated, it becomes difficult to generate radiated sound and transmitted sound. When the sound is silenced by the exhaust silencer, the device length (cavity length) is long to mute the low frequency sound. The effect is greater.

  FIG. 5 shows an insertion loss characteristic diagram of the exhaust silencer device. In FIG. 5, symbol A indicates insertion loss characteristics when the exhaust silencer device is in the first state (a state where the cavity length is long), and symbol B indicates insertion when the exhaust silencer device is in the second state (a state where the cavity length is short). The loss characteristic is indicated by symbol C, and the insertion loss characteristic in the absence of the exhaust silencer device is shown.

  In the case of no device, the sound is not muted at all. However, in the first state, the sound level is increased in a low frequency range (for example, 700 Hz or lower), and in the second state, the sound level is decreased in a frequency range of 700 Hz or higher. Will increase. If there is no switching of the state of the exhaust silencing device, only the insertion loss characteristic (silencing characteristic) of either the first state or the second state is obtained. Therefore, the frequency range in which the radiation noise reduction effect can be obtained is widened.

  Since the pulsation fundamental frequency is low when the engine is running at a low speed, it is necessary to mute the low frequency as a countermeasure against radiation noise. 1 (L = 150 mm), and low-frequency noise reduction is possible.

  On the other hand, at a high engine speed, the exhaust flow rate increases, the switching valve 21 is switched to the second switching position by the exhaust gas pressure, and the exhaust silencing device is in the second state (L = 100 mm and L = 50 mm). The sound is silenced by the cavity lengths of 100 mm and 50 mm, and the sound can be silenced in a wide frequency range.

  As the radiated sound, sound of 20 to 800 Hz (in the case of a four-cylinder engine) that is the basic order of pulsation is transmitted and is generated from the shell, end plate, etc. of the muffler, and 600 Hz to 2000 Hz that is a natural value of the shell and end plate (example) ) Is generated as a radiated sound. By using the exhaust silencer device of this embodiment, the level of the generated radiated sound from the low frequency range to the high frequency range can be reduced. The frequency from which the low frequency region is attenuated may be adjusted by the device length (cavity length).

  In order to prevent the generation of noise due to the switching valve 21 coming into contact with the internal partition wall 7 and the exhaust pipe 1 when the switching valve 21 closes the second communication hole 15 and the third communication hole 17, Stainless steel mat members 31 and 33 knitted with stainless steel wire may be provided around the second communication hole 15 and the third communication hole 17. Further, if a small hole having a diameter of about 1 mm to 5 mm is provided at the inlet of the exhaust silencer device, the damping effect is further increased.

  In the second state, if the resonator chambers having two different cavity lengths are not necessary and only one is required, the third communication hole 17 may be omitted.

  The effects of the exhaust silencing device of this embodiment are summarized as follows.

(1) Without increasing the device capacity, it is possible to reduce the generation level of radiated sound from a low frequency range to a high frequency range, and a wide range of silencing effects can be expected.

(2) Since the switching valve is an exhaust gas pressure sensitive type, an actuator such as a motor is not used for switching driving of the switching valve, and the cost is reduced.

(3) The device configuration is simple and does not significantly increase the weight.

(4) There is no need for muffler rigidity change and mass addition, which are conventional countermeasures against radiated sound, and it is easy to standardize the muffler body simply by adding an exhaust silencer device.

(5) With this exhaust silencer device, the discharge sound level can be reduced from the low frequency range to the high frequency range.

(6) When mounted on a system in which radiated sound is likely to be generated due to thinning of the exhaust system, the system effect is great.

Sectional drawing which shows the 1st state of the exhaust silencer device by embodiment. Sectional drawing which shows the 2nd state of the exhaust silencer device by embodiment. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. The expanded detailed sectional view of the principal part of the exhaust silencer device by an embodiment. The graph which shows the insertion loss characteristic with respect to a frequency.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exhaust pipe 3 Exhaust passage 5 Resonator case 7 Internal partition 9 1st resonator chamber 11 2nd resonator chamber 13 1st communicating hole 15 2nd communicating hole 17 3rd communicating hole 19 Axis 21 Switching valve 23 Pressure receiving plate 25 Bridge part 27 Slit hole 29 Torsion spring

Claims (4)

A resonator case (5) defining a resonator chamber (5A) in communication with the exhaust passage (3) by the communication hole (13);
A switching valve (21) that performs switching operation according to the pressure of the exhaust gas flowing through the exhaust passage (3),
The exhaust silencer device, wherein an effective length of the resonator chamber (5A) is changed by a switching operation of the switching valve (21). A resonator chamber (5A) provided outside the exhaust pipe (1) and communicated with the exhaust passage (3) by the exhaust pipe (1) by a first communication hole (13) provided in the exhaust pipe (1). A resonator case (5) demarcating;
A switching valve (21) that performs switching operation according to the pressure of the exhaust gas flowing through the exhaust passage (3),
The resonator chamber (5A) is divided into a first resonator chamber (9) and a second resonator chamber (11) by an internal partition wall (7), and the first resonator chamber (9) is connected to the first communication chamber. A hole (13) communicates with the exhaust passage (3), and the first resonator chamber (9) and the second resonator chamber (11) are communicated with each other in the second partition wall (7). An exhaust silencer device characterized in that the second communication hole (15) is opened and closed by the switching valve (21), and communicates with each other through a hole (15).   The cavity lengths of the first resonator chamber (9) and the second resonator chamber (11) are different from each other, and the second resonator chamber (11) is opened to the exhaust pipe (1). 3 communication holes (17) communicate with the exhaust passage (3), and the switching valve (21) opposes the second communication hole (15) and the third communication hole (17). The exhaust silencer device according to claim 2, wherein the exhaust silencer device is opened and closed in an open / close relationship. A pressure receiving plate (23) that receives the pressure of the exhaust gas flowing through the exhaust passage (3) and drives the switching valve (21) in a direction to close the second communication hole (15); and the second communication hole. (15) spring means (29) for urging the switching valve (21) in the direction of opening,
The switching valve (21) opens the second communication hole (15) until the driving force by the exhaust gas pressure acting on the pressure receiving plate (23) overcomes the spring force by the spring means (29), The second communication hole (15) is closed when the driving force by the exhaust gas pressure acting on the pressure receiving plate (23) overcomes the spring force by the spring means (29). The exhaust silencer device described.

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