JPH0669312U - Silencer - Google Patents

Abstract

(57) [Summary] [Purpose] The exhaust pipe and the resonator pipe of the silencer are variably controlled to attenuate the exhaust sound components in two frequency bands at the same time. [Structure] The exhaust pipe 21 is composed of fixed pipes 22 and 23 and a movable pipe 24 that is a movable member, and both ends of the movable pipe 24 are fixed pipes 22,
Plugged into 23. The movable tube 24 has a resonator tube 28
Is connected to one end of the resonator tube 28, and the other end of the resonator tube 28 is connected to the sound absorber section 26.
It is inserted in the fixed tube 29 provided in the. Since the slide amount Ls of the resonator pipe 28 inserted into the fixed pipe 29 of the sound absorber portion 26 which is the closed section changes the mass of the entire sound absorber,
Determine the resonance frequency. Provided with a movable tube slide mechanism 30,
The movable tube 24 and the movable tube 24 are slid in the axial direction (the horizontal direction in the drawing). Along with the slide, the entire length of the resonator tube 28 connected to the movable tube 24 is variably controlled.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a muffler that muffles exhaust noise accompanying exhaust from an engine.

[0002]

[Prior art]

 An example of this type of conventional silencer is described in Japanese Utility Model Laid-Open No. 2-13119. FIG. 6 is a diagram showing a silencer disclosed in Japanese Utility Model Laid-Open No. 2-13119. The muffler 10 penetrates the shell 11 and is supported by end plates 12 and 13, and also a muffler pipe (exhaust pipe) 14 that guides engine exhaust from the left side to the right side in the drawing, and the muffler pipe 14 closer to the end plate 12. And a resonator tube 15 connected to the part of.

In this conventional silencer, the resonator tube 15 is made of a shape memory alloy so that the length (total length) of the resonator tube 15 changes depending on the temperature. No variable control mechanism is provided.

[0004]

[Problems to be solved by the device]

However, in the conventional example of FIG. 6 described above, the length of the resonator pipe 15 can be changed, but the length of the muffler pipe 14 itself is fixed, so that as shown in FIG. Although it is possible to set the length of the resonator pipe 15 in order to attenuate the higher-order component (3f ₁ ) in the frequency characteristic of the exhaust sound that has two peaks, It is difficult to match the component with the component (f ₁ ) to be attenuated by the exhaust pipe, and it is difficult to avoid exhaust muffled noise (exhaust resonance) in a certain engine rotation range.

The present invention provides a muffler that avoids exhaust muffled noise by variably controlling the total length of the exhaust pipe, and that the sound absorber is always adapted to a fundamental frequency based on the variably controlled total length of the exhaust pipe. The purpose is to

[0006]

[Means for Solving the Problems]

 To this end, the present invention variably controls the total length of the exhaust pipe and the resonator pipe in a silencer that includes an exhaust pipe that penetrates through the housing and a resonator pipe that has one end connected to a sound absorber. In addition, the exhaust pipe and the resonator pipe are integrated.

[0007]

[Action]

 According to the present invention, the exhaust pipe penetrating the inside of the housing and the resonator pipe whose one end is connected to the sound absorber are variably controlled in length depending on, for example, the engine speed, and therefore are attenuated by the exhaust pipe and the resonator pipe. The components of exhaust noise that can be generated have predetermined frequencies as shown in FIG. 2, and desired attenuation characteristics can be obtained.

Further, according to the present invention, since the exhaust pipe and the resonator pipe are integrated, a control system for variably controlling the entire length of them can be shared, and the exhaust pipe system can be easily manufactured. become.

[0009]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing the configuration of a first embodiment of a silencer of the present invention. In the figure, reference numeral 21 is an S-turn type exhaust pipe. This silencer is designed as a controlled silencer. The exhaust pipe 21 includes fixed pipes 22 and 23 and a movable pipe 24 that is a movable member. The fixed pipe 22 has its left end (inlet side) connected to an engine (not shown), penetrates a sound absorber 26 provided in the housing 25, and further has a support member 27 provided substantially in the center of the housing 25. The right end is supported by. On the other hand, the U-shaped portion of the fixed tube 23 is supported by the support member 27. The movable tube 24 has its both ends inserted into the fixed tubes 22 and 23.

One end of a resonator pipe 28 is connected to the movable pipe 24, and the other end of the resonator pipe 28 is inserted into a fixed pipe 29 provided in the sound absorber portion 26. Here, the slide amount Ls of the resonator pipe 28 inserted into the fixed pipe 29 of the sound absorber portion 26, which is the closed section, changes the mass of the entire sound absorber and thus determines the resonance frequency described later. The resonator tube 28 and the sound absorber section 26 constitute a resonator (resonator).

A movable tube slide mechanism 30 is connected to the U-shaped curved portion of the movable tube 24, and the movable tube slide mechanism 30 is provided between the support member 27 and the U-shaped curved portion of the movable tube 24. The movable tube 24 is slid in the axial direction (left and right direction in the drawing) against the spring force of the spring 31 provided in the. Along with the slide, the resonator pipe 28 connected to the movable pipe 24 also slides at the same time. When variably controlling the total length of the exhaust pipe 21 by the above-mentioned slide, the movable pipe sliding mechanism 30 is controlled according to the engine speed, for example. Good.

Next, the operation of the muffler of this embodiment will be described using specific numerical values. First, as shown in FIG. 1, the total length of the resonator pipe 28 (corresponding to the sound absorber mass) is L ₁ , the total length of the exhaust pipe 21 (engine outlet to exhaust pipe outlet) is L ₂ , the movable pipe 24 and the resonator pipe. When the movable slide length of 28 is Ls, set L _{2 so} that 4000 ≦ L ₂ ≦ 4400 (mm), and set so that Ls = 200 (mm).

Here, for comparison, in the case of a silencer in which the exhaust pipe formed in an S shape as in FIG. 1 does not slide and its total length L ₂ is fixed to L ₂ = 4400 (FIG. 7). The model diagram is shown in Fig. 1). In this case, the frequency f at which f _n = (C / 4L ₂ ) × (2n + 1); (where n = 0, 1, 2, ..., C: sound velocity = 331.5 + 0.61t (m / s)) Exhaust muffled noise (excited by engine secondary components) can occur at _n . As a realistic value that this expression can take, when n = 1, 2 and t = 250 ° C., f ₁ = 86 Hz (2590 rpm) and f ₂ = 144 Hz (4320 rpm).

On the other hand, in the case of the present embodiment, the resonance with the peak f ₁ as shown in the frequency characteristic diagram of the exhaust sound of FIG. 2 is avoided by changing the total length of the exhaust pipe, and the resonance is added to the added resonator. Therefore, the component having a peak at 3f ₁ (higher-order component of f ₁ ) can be attenuated. Specifically, as shown in FIG. 3, the total length L _{2 of the} exhaust pipe may be variably controlled between 4000 and 4200 (mm). The variable control is performed by driving the movable pipe slide mechanism 30 and the movable pipe 24 and the resonator. The movable slide length Ls of the tube 28 may be adjusted.

In the adjustment, for example, the total length L _{2 of the} exhaust pipe is changed from 4200 (mm) to 4000 (mm) to avoid resonance up to a certain frequency, and L ₂ has a minimum value of 4000 (mm). Then, when it becomes impossible to avoid further resonance, resonance is avoided by changing L ₂ to a maximum value near 4200 (mm) instantly. Further, the high-order component 3f ₁ of the frequency f ₁ thus attenuated is absorbed by adjusting it to the resonance frequency of the sound absorber using the resonator tube 28. This sound absorption is possible because L ₂ is increased and L ₁ is increased at the same time. Further, by setting L ₂ to a minimum value of 4000 (mm) in the high engine speed range, exhaust efficiency can be improved.

Further, in the above embodiment, if the resonance frequency of the resonator is variably controlled, the higher order components of muffled sound in different modes can be attenuated. That is, in order to change the resonance frequency of the resonator from the range A (258 to 273 Hz) shown in FIG. 3 to the range B (240 to 252 Hz) surrounded by the dotted line, the sound absorber section indicated by diagonal lines in FIG. The volume of can be changed.

FIG. 4 is a diagram showing the configuration of a second embodiment of the silencer of the present invention. The same parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. The difference between the second embodiment and the first embodiment is that the connection positions of the movable tube 24 and the resonator tube 28 are changed. That is, in the first embodiment, the resonator pipe 28 is connected to the center of the straight portion of the movable pipe 24 which is inserted into the fixed pipe 22, but in this embodiment, the intersection of the straight portion and the curved portion of the movable pipe 24 is connected. The resonator pipe 28 is connected in the vicinity. With the above change, the connection position of the movable tube slide mechanism 30 and the spring 31 is changed from the curved portion of the movable tube 24 to the curved portion of the resonator tube 28 as shown in FIG.

In the second embodiment, the movable slide length Ls of the movable pipe 24 and the resonator pipe 28 can be adjusted by driving the movable pipe slide mechanism 30 as in the first embodiment. The same effect as is obtained.

FIG. 5 is a schematic diagram showing a schematic configuration of a third embodiment of the silencer of the present invention. This embodiment is based on the first embodiment. The difference from the first embodiment is that the movable part and the fixed part are integrated in the exhaust pipe 32 and the resonator pipe 33, respectively. The bellows parts 32a, 32b and 33a as shown in the figure are provided in the pipe 32 and the resonator pipe 33. As the bellows portion, for example, a flexible tube having the structure of the exhaust pipe 1 shown in Fig. 1 of Japanese Utility Model Laid-Open No. 61-86531 is used.

In this embodiment, the slide length Ls is variable without changing the overall length of the muffler body Lf. Therefore, the movable tube slide mechanism and the bar as in the first embodiment are unnecessary.

[0021]

[Effect of device]

 Thus, the muffler of the present invention variably controls the exhaust pipe and the resonator pipe as described above, and since the exhaust pipe and the resonator pipe are integrated, the exhaust sound of a predetermined frequency as shown in FIG. 2 is generated. A desired damping characteristic for attenuating the components is obtained, and a control system for variably controlling the total length of the exhaust pipe and the resonator pipe is shared, which facilitates manufacturing of the exhaust pipe system.

[Brief description of drawings]

FIG. 1 is a diagram showing the configuration of a first embodiment of a silencer of the present invention.

FIG. 2 is a characteristic diagram showing frequency characteristics of exhaust sound.

FIG. 3 is a diagram for explaining variable control of the entire lengths of the exhaust pipe and the resonator pipe of the first embodiment.

FIG. 4 is a diagram showing the configuration of a second embodiment of the silencer of the present invention.

FIG. 5 is a schematic diagram showing a schematic configuration of a third embodiment of the silencer of the present invention.

FIG. 6 is a diagram for explaining a conventional technique.

FIG. 7 is a diagram for explaining a conventional technique.

[Explanation of symbols]

 21 Exhaust pipe 22 Fixed pipe 23 Fixed pipe 24 Movable pipe 25 Housing 26 Sound absorber 28 Resonator pipe 29 Fixed pipe 30 Movable pipe slide mechanism 31 Spring

Claims (1)

[Scope of utility model registration request] 1. A silencer comprising an exhaust pipe penetrating through a housing and a resonator pipe having one end connected to a sound absorber, wherein the exhaust pipe and the resonator pipe are variably controlled in total length, and the exhaust pipe and the resonator pipe are connected to each other. A silencer characterized by integrating a resonator tube.