JPH0710410U - Silencer - Google Patents

Abstract

(57) [Abstract] [Purpose] The present invention relates to a silencer for an automobile, and in particular,
The present invention relates to a muffler in which the mute center frequency of a resonator is variable, and it is an object of the present invention to reliably muffle discharged sound over a wide range of frequency bands. A tip of a resonator pipe 59 is inserted into a resonator chamber 55, and an opening 71 made up of a plurality of small holes 69 is formed in a portion of the resonator pipe 59 located inside the resonator chamber 55. In the resonator pipe 59, a moving body 77 having a plurality of porous bodies 73, 74, 75 having different porosities adjacent to each other in the axial direction is arranged, and the moving body 77 is moved along the resonator pipe 59 by an actuator 87. To be freely movable.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a muffler for an automobile, and more particularly to a muffler having a variable mute center frequency of a resonator.

[0002]

[Prior art]

 Conventionally, as a muffler for an automobile, for example, one disclosed in Japanese Utility Model Laid-Open No. 59-58711 is known.

FIG. 5 shows a muffler of this type, and in the figure, reference numeral 11 denotes a muffler body which is sealed by end plates 13 and 15. The inside of the muffler body 11 is divided into four by partition plates 17, 18, and 19, and a first expansion chamber 21, a second expansion chamber 22, a first resonator chamber 23, and a second resonator chamber 24 are formed. Has been formed.

An inlet pipe 25 is opened in the first expansion chamber 21 by penetrating the end plate 13 and the partition plates 17 and 18, and is opened coaxially with the inlet pipe 25 in the first resonator chamber 23. A resonator pipe 27 is installed.

A return pipe 29 is provided so as to pass through the partition plate 18, and a resonator pipe 31 that opens to the second resonator chamber 24 is provided coaxially with the return pipe 29.

An outlet pipe 33 is arranged so as to penetrate through the partition plates 18 and 19 and the end plate 15, and a large number of small holes 35 are formed in a portion of the outlet pipe 33 located inside the second expansion chamber 22. Has been done.

In the silencer configured as described above, the exhaust gas introduced from the inlet pipe 25 into the silencer body 11 is silenced by expansion in the first expansion chamber 21 and the second expansion chamber 22, respectively. In addition, the first resonator chamber 23 and the second resonator chamber 24 are mainly affected by the resonance.

[0008]

[Problems to be solved by the device]

 However, in such a conventional silencer, in the second resonator chamber 24, the exhaust gas that has passed through the first expansion chamber 21 and flowed into the second expansion chamber 22 is silenced. However, there was a problem that the pulsating pressure of the exhaust gas was small and it was difficult to obtain a sufficient silencing effect.

Further, in the conventional silencer, since the silencing center frequency of the ejection sound to be silenced by the first and second resonator chambers 23 and 24 is fixed, only the ejection sound of a predetermined frequency can be silenced. However, there is a problem that it is difficult to sufficiently reduce the vehicle interior noise (muffled sound).

The present invention has been made in order to solve such a conventional problem, and an object of the present invention is to provide a silencer that can reliably muffle the discharge sound over a wide frequency band.

[0011]

[Means for Solving the Problems]

 The muffler according to the present invention is configured such that a tip of a resonator pipe is inserted into a resonator chamber, an opening formed of a plurality of small holes is formed in a portion of the resonator pipe located in the resonator chamber, and the inside of the resonator pipe is further formed. In addition, a plurality of porous bodies having different porosities are arranged adjacent to each other in the axial direction, and a movable body is configured to be movable along the resonator pipe by an actuator.

[0012]

[Action]

 In the muffler of the present invention, for example, the actuator is actuated in accordance with the engine speed to move the moving body along the resonator pipe, so that the porous body located at the opening of the resonator pipe is removed. The average porosity changes, which changes the effective opening area of the resonator pipe and changes the silencing center frequency.

[0013]

【Example】

 Hereinafter, the details of the present invention will be described with reference to embodiments shown in the drawings. FIG. 1 shows an embodiment of a muffler of the present invention. In the figure, reference numeral 41 denotes a muffler body sealed by end plates 43 and 45.

The interior of the muffler body 41 is divided into four by partition plates 47, 48, 49 to form a first expansion chamber 51, a second expansion chamber 52, a third expansion chamber 53 and a resonator chamber 55. Has been done.

An inlet pipe 57 is opened to the first expansion chamber 51 by penetrating the end plate 43 and the partition plates 47 and 48, and a resonator which is coaxial with the inlet pipe 57 and is opened to the resonator chamber 55. A pipe 59 is provided.

A return pipe 61 is provided so as to penetrate through the partition plates 47 and 48, and a large number of small holes 63 are formed in a portion of the return pipe 61 located inside the second expansion chamber 52.

An outlet pipe 65 is arranged so as to penetrate through the partition plates 47, 48, 49 and the end plate 45, and a large number of small holes are formed in a portion of the outlet pipe 65 located inside the third expansion chamber 53. 67 is formed.

However, in this embodiment, the tip of the resonator pipe 59 is inserted into the resonator chamber 55, and as shown in FIG. 2, a large number of parts are provided in the portion of the resonator pipe 59 located inside the resonator chamber 55. An opening portion 71 composed of a small hole 69 is formed.

In this embodiment, the total opening area of the opening 71 is the same as the sectional area of the resonator pipe 59. As shown in FIG. 3, a moving body 77 formed by integrally molding three porous bodies 73, 74, and 75 having different porosities adjacent to each other in the axial direction is arranged in the resonator pipe 59. ing.

In this embodiment, the porous bodies 73, 74, 75 are made of, for example, foam ceramics, and the porosities of the porous bodies 73, 74, 75 are 80%, 60%, It is set at 40%.

A plate 79 is fixed to the rear end surface of the moving body 77, and a spindle 81 is fixed to the center of the plate 79. The spindle 81 extends through the blind plug 83 arranged at the tip of the resonator pipe 59 and the end plate 45 of the muffler body 41 to the outside.

A rack 85 is formed at the rear end of the spindle 81, and a pinion 89 rotated by a motor 87 which is an actuator is meshed with the rack 85.

Reference numeral 91 indicates a control device for controlling the drive of the motor 87. The control device 91 inputs the rotation speed of the engine, drives the motor 87 according to the rotation speed, and moves the moving body. 77 is moved to a predetermined position according to the number of rotations.

In the above-described silencer, the exhaust gas introduced into the silencer main body 41 from the inlet pipe 57 is supplied to the first expansion chamber 51, the second expansion chamber 52, and the third expansion chamber 53, respectively. It receives a muffling effect due to expansion, and also receives a muffling effect mainly due to resonance in the resonator chamber 55.

In the silencer described above, the control device 91 drives the motor 87 in accordance with the engine speed to move the moving body 77 to a predetermined position along the resonator pipe 59. The average porosity of the porous bodies 73, 74, 75 located in the opening 71 of the resonator pipe 59 changes, which changes the actual opening area of the resonator pipe 59, which is apparent from the well-known Helmholtz equation. Thus, the mute center frequency is changed.

That is, in this embodiment, when the engine speed is relatively high, the moving body 77 is located on the tip side of the resonator pipe 59 and the opening of the resonator pipe 59 is shown, as shown in FIG. Since the moving body 77 is not located in the portion 71, as a result, the actual opening area of the opening 71 of the resonator pipe 59 becomes 100%, the silencing center frequency becomes relatively large, and the ejection of a relatively high frequency is performed. The sound is muted.

When the engine speed decreases, as shown in FIG. 4B, the moving body 77 is moved to the inlet side of the resonator pipe 59, and is moved to the opening 71 of the resonator pipe 59. The porous body 73 having a porosity of 80% of the body 77 is located, and as a result, the actual opening area of the opening 71 of the resonator pipe 59 becomes 80%, and the silencing center frequency becomes lower than that of (a), The ejection sound of a lower frequency is muted compared to a).

When the engine speed further decreases, as shown in FIG. 4C, the moving body 77 is further moved to the inlet side of the resonator pipe 59, and the opening 71 of the resonator pipe 59 is The porous body 74 having a porosity of 60% of the moving body 77 is located, and as a result, the actual opening area of the opening 71 of the resonator pipe 59 becomes 60%, and the silencing center frequency becomes lower than that in (b). The ejection sound with a lower frequency than that in (b) is silenced.

When the engine speed further decreases, the moving body 77 is further moved to the inlet side of the resonator pipe 59 as shown in FIG. 4D, and is moved to the opening 71 of the resonator pipe 59. The porous body 75 having a porosity of 40% of the body 77 is located, and as a result, the actual opening area of the opening 71 of the resonator pipe 59 becomes 40%, and the silencing center frequency becomes lower than that in (c). The ejection sound of a lower frequency than that in (c) is silenced.

Therefore, in the silencer configured as described above, when the motor 87 is driven by the control device 91 and the moving body 77 is moved along the resonator pipe 59 according to the engine speed. , The average porosity of the porous bodies 73, 74, 75 located in the opening 71 of the resonator pipe 59 changes, which changes the substantial opening area of the resonator pipe 59 and changes the silencing center frequency. It is possible to reliably muffle the discharge sound over a wide range of frequency bands, and as a result, it is possible to sufficiently reduce the noise in the passenger compartment (the muffled sound).

Further, in the above-described muffler, since the resonator pipe 59 is provided at a position where the pulsating pressure of exhaust gas is relatively large, it is possible to obtain a sufficient muffling effect. It should be noted that in the above-described embodiment, an example in which the motor 87 is used as the actuator has been described, but the present invention is not limited to such an embodiment, and for example, an actuator such as an air cylinder or hydraulic cylinder is used. Of course, you can do that.

Further, in the above-mentioned embodiment, an example in which the porous bodies 73, 74, 75 are formed in a solid cylinder shape has been described, but the present invention is not limited to this embodiment, and for example, Of course, it may be formed in a cylindrical shape.

[0033]

[Effect of device]

 As described above, in the silencer of the present invention, when the actuator is actuated corresponding to the engine speed and the moving body is moved along the resonator pipe, the porous body located at the opening of the resonator pipe is The average porosity changes, which changes the actual opening area of the resonator pipe and changes the center frequency of the sound deadening, which has the advantage of being able to reliably mute the discharge sound over a wide range of frequency bands. .

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a silencer according to the present invention.

FIG. 2 is an enlarged sectional view showing the resonator pipe of FIG.

FIG. 3 is a side view showing the moving body of FIG. 1 in an enlarged manner.

FIG. 4 is an explanatory diagram showing a state in which the moving body of FIG. 1 is moved corresponding to the engine speed.

FIG. 5 is a cross-sectional view showing a conventional silencer.

[Explanation of symbols]

 55 Resonator Chamber 59 Resonator Pipe 69 Small Hole 71 Opening 73, 74, 75 Porous Body 77 Moving Body 87 Motor

Claims (1)

[Scope of utility model registration request] 1. The resonator pipe (59) is inserted at its tip into a resonator chamber (55), and the resonator chamber (55) of the resonator pipe (59) is also provided.
An opening (71) consisting of a plurality of small holes (69) is formed in a portion located inside, and a plurality of porous bodies (73, 73) having different porosities are further provided in the resonator pipe (59).
(74, 75) adjacent to each other in the axial direction (77)
The moving body (77) and the actuator (8
7) A silencer characterized by being configured to be movable along the resonator pipe (59) by 7).