JPH01110821A - Exhaust silencer for engine - Google Patents

Abstract

PURPOSE:To remove the harsh noise by switching a sound absorbing type passage and an expansion chamber type passage. CONSTITUTION:The first passage 3 having the sound absorbing members 7 and 8 and the second passage 4 having expansion chambers 11-13 are formed. A communication passage 25 for the communication between the both passages 3 and 4 is formed, and an opening/closing valve 30 is installed in one passage among the both passages on the upstream from the communication position. The sound quality is changed by switching the opening and closing of the opening/closing valve 30. Therefore, the harsh noise can be removed, and the preferable sound can be generated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an exhaust silencer for muffling engine exhaust.

(Prior Art) Various engine exhaust silencers have been proposed in the past, which are designed to improve the exhaust noise silencing effect by providing an expansion chamber or the like and devising an exhaust flow path.

For example, in Japanese Utility Model Application Publication No. 61-101625, a first path (first
an outlet pipe); and a second path (second outlet pipe) that joins the first path in the vicinity of the tail pipe through a relatively long path passing through a plurality of expansion chambers from the inlet pipe. The silencer is equipped with a switching valve at the confluence of both routes that switches between opening the first route and closing the second route and closing the first route and opening the second route. structure is disclosed. In this silencer, the switching valve is switched in accordance with the engine speed, etc., thereby reducing exhaust pressure in a high speed range and improving the silencing effect in a low speed range.

Although conventional silencers like this are designed to enhance the silencing effect and reduce exhaust noise, they cannot completely eliminate exhaust noise, and it is not possible to change the sound quality. This was not taken into consideration, and there was room for improvement in order to prevent the sound emitted from the silencer from being harsh.

(Purpose of the Invention) In view of the above circumstances, the present invention has the objective of providing a sufficient sound deadening effect, removing harsh sounds, and providing a desirable sound that matches the feeling of driving. It provides an engine exhaust silencer that can be modified and tuned.

(Structure of the Invention) The engine exhaust silencer of the present invention includes a 111th passage whose main part is a sound-absorbing material passage having a sound-absorbing material, and a second passage whose main part is an expansion chamber, and each of these paths Separate tail pipes are provided at the terminal ends, and communication passages are provided upstream of each of the tail pipes to communicate the two routes, and an on-off valve is provided in one of the routes upstream from the point of communication by the communication passages. .

According to this configuration, ll? The volume and sound quality are changed according to the switching of the opening m of the lff1 valve, and the sound quality is adjusted by the two tailpipes.

(Example) Fig. 1 shows a specific structure of a silencer according to an embodiment of the present invention in a sectional view, Fig. 2 shows the configuration of an exhaust path of this silencer, and Figs. The exhaust route of this silencer is roughly expanded and schematically shown when the on-off valve described later is opened and when it is closed. In these figures, exhaust gas from an engine (not shown) flows into an inlet pipe 2 that has entered the case 1 of the silencer, and a first path 3 and a second path 4 are connected from this inlet pipe 2. Each branched path 3.4 is individually equipped with a tail pipe 5.6 at its end.

The first path 3 is mainly a sound-absorbing passage having a sound-absorbing material, and for example, sound-absorbing materials 7.8 are provided in the middle of the path and at the tail pipe 5.

In the specific structure shown in FIG. 1, the upstream passage 9 of the first passage 3 is disposed approximately at right angles to the inlet pipe 2, one end thereof is connected to the inlet pipe 2, and the other end of this passage 9 is connected to the inlet pipe 2. A substantially perpendicular passage 10 is connected, and a tail pipe 5 is connected to an end of this passage 10 facing outside of the case 1. In the upstream passage 9, a sound absorbing material 7 such as glass wool is loaded between an inner cylinder 9a made of a perforated plate (punch metal) and an outer cylinder 9b surrounding it. A sound absorbing material 8 such as glass wool is loaded between an inner cylinder 5a made of a plate and an outer cylinder 5b surrounding the inner cylinder 5a.

Further, the second route 4 has an expansion chamber as a main part, and includes, for example, three expansion chambers 11, 12, 13 in the middle of the route. In the specific example shown in FIG.
3, but in the order of exhaust passage, of these, the one on the right side of the diagram is 1.
The second expansion chamber 11 is arranged so that the left side is the second expansion chamber 12, and the space between them is the third expansion chamber 13, and a resonance chamber 17 is formed on the right side of the first expansion chamber 11.
The second I! is arranged so that the expansion chambers 11, 12, 13 and the resonance chamber 17 are communicated with each other. A path 4 is formed. That is, one end of the upstream passage 18 of the second passage 4 parallel to the upstream passage 9 of the first passage 3 is connected to the inlet pipe 2, and the passage 1
A first expansion chamber 11 communicates with the other end of the 8, and a resonance chamber 17 communicates through a pipe, and a second expansion chamber 12 communicates with the second expansion chamber 11 of the upper device through a pipe 20. Furthermore, a third expansion chamber 13 communicates with the second expansion chamber 12 via a pipe 21 penetrating the partition wall 14. A passage 22 communicating with the third expansion chamber 13
A tail vibro is connected to the end facing outward from the case. In the embodiment shown in the figure, the upstream passage 18 has an inner cylinder 18a made of a perforated plate and an outer aisb, in order to provide an auxiliary sound absorbing effect by the sound absorbing material even in the second passage 4 whose main part is the expansion chamber. 6, the tail vibro is also structured to have a sound absorbing material 24 between the inner B6a made of a perforated plate and the outer cylinder 6b.

Further, the first route 3 and the second route 4 are connected to the tail pipes 5 and 6.
are communicated with each other via a communication path 25 immediately upstream of the
In the specific structure shown in FIG. 1, the passages 108.22 immediately upstream of both tail vibes 5.6 are formed of perforated plates, so that the space in the case 1 between them is used as the communication passage 25.

An on-off valve 30 is provided in the first path 3 upstream of the communication point by the communication path 25. This on-off valve 30 is arranged in the passage 10 near the above-mentioned communication point, and the drive mechanism 3
1 to open and close the door.

As shown in FIGS. 4 and 5, for example, the drive mechanism 31 includes a lever 32 attached to one end of the shaft 30a of the 17113F1 valve 30, a spring 33 that biases the lever 32 in the closing direction, and a lever. 32 and a stopper 35. Then, the lever 32 is actuated by the actuator 36 via the wire 34, and the actuator 36 is operated by the controller 37 that receives the acceleration detection signal 38, etc.
1.

The drive mechanism 31 is placed on the side of the resonance chamber 17 inside the case 1, so that it is protected by the case 1, and
The influence of exhaust heat is avoided by the heat insulation effect in the space constituting the resonance chamber 17.

The operation of the silencer of this embodiment as described above will be explained based on FIGS. 3(a) and 3(b).

When the on-off valve 30 provided in the first path 3 is opened, the exhaust gas flowing into the inlet pipe 2 is transferred to the first path 3 and the second path 4, as shown by the arrow in FIG. 3(a). The water is divided into two parts, passes through each path 3.4, and is discharged from the tail vibe 5.6. Then, the exhaust gas passing through the 111th path 5 is
The sound absorbing material 7 of the upstream passage 9 and the sound absorbing material 8 of the tail vibe 5 absorb sound such as crackling noise and airflow noise.

When the rMr11 valve 30 is closed and the first path 3 is interrupted, the exhaust gas passes through the second path 4 as shown by the arrow in FIG. 3(b). In this case, as described above, the passages 108 and 22 immediately upstream of each tail vibrator 5 and 6 are formed of perforated plates and communicated with each other via the communication passage 25, so that the Exhaust gas is discharged from the tail vibro on the terminal side and also passes through the communication path 25 and is exhausted from the tail vibro 5 on the terminal side of the first path 3, so it feels unnatural because it is exhausted only from the tail vibro on one side. This prevents a situation in which the sound quality is changed, and maintains the effect of changing and adjusting the sound quality as described later.

When the on-off valve 30 is in the closed state as described above, the exhaust gas passing through the second path 4 is
2.13, the sound absorbing material 23, 24 absorbs sound, and the resonance chamber 17 removes specific frequency components. Furthermore, the on-off valve 30 is the 11th! Since the passage 9 is closed downstream of the upstream passage 9, the passage 9 upstream of the on-off valve 30 serves as a resonance part, and this part also has the effect of removing specific frequency components.

The effect of this kind of action on the volume and quality of exhaust sound is
This will be explained with reference to FIGS. 6 to 9.

When the on-off valve 30 of the first path 3 is closed, the first path similar to the above embodiment. In a passage configuration with a second passage 3.4,
If the on-off valve 30 is provided in the upstream end of the first path 3 as shown in FIG. 6(a), and the IIA structure is used, and as shown in FIG. 6(b)
As shown in the 11th! Comparing the case where the on-off valve 30 is provided downstream from the upstream passage 9 of the channel, the sound pressure attenuation at various frequencies is as shown by the broken line in Fig. 6(C) in the former case, whereas , the latter case is shown by a solid line in the figure. In other words, according to the structure shown in FIG. 6(b), which has the passage 9 serving as a resonance part in the first path 3 upstream of the on-off valve 30, compared to the structure shown in FIG. 6(a), At A, the sound pressure attenuation field increases.

Furthermore, when the on-off valve 30 of the first path 3 is closed, there are two cases in which the passage 9 upstream of the on-off valve 30 is a simple pipe as shown in FIG. When comparing the case where the passage 9 is expanded by providing an outer cylinder 9b, the sound pressure attenuation amount in the former case is as shown by the broken line in FIG. In this case, as shown by the solid line in the figure, the sound pressure attenuation in the specific intermediate frequency range 8 is increased.

Therefore, according to the structure of FIG. 7(b), that is, the structure of the embodiment described above, when the on-off valve 30 is closed, the intermediate frequency range is The sound pressure attenuation effect can be enhanced.

On the other hand, when the on-off valve 30 is opened, there are two cases in which the upstream passage 9 of the first path 3 does not have the sound absorbing material 7 as shown in FIG. 9 is equipped with the sound absorbing material 7 (corresponding to the above embodiment), in the former case the sound pressure attenuation port is as shown by the broken line in FIG. 8(C), In the latter case, as shown by the solid line in the figure, the amount of sound pressure attenuation in the relatively high frequency range C is increased. Therefore, when the on-off valve 30 is opened, the sound absorbing material 7 is The passage 9 has the function of increasing the sound pressure attenuation effect in the high frequency range.

FIG. 9 shows the sound volume (dB) at various frequencies in the structure of the above embodiment when the on-off valve 30 is closed (dashed line).
and when opened (solid line).

As shown in this figure, not only the overall sound volume differs when the on-off valve 30 is closed and when it is opened, but also the on-off valve 30
When the on-off valve 30 is closed, the volume peaks in a relatively low frequency range (marked by The sound quality also changes, with the volume reaching its peak at the 8Y section), giving a sensually sporty sound. In this case, the sound quality of the exhaust sound passing through each tail pipe 5.6 is also related to the acoustic characteristics according to the shape, inner diameter, etc. of the tail pipe 5.6, so for example, the inner diameter of the tail pipe 5 on the first path 3 side The sound quality can also be adjusted by setting the acoustic characteristics of the tail pipe 5.6, such as by making it smaller than the inner diameter of the tail vibro on the second shuttle 4 side.

In this way, the sound quality of the exhaust sound can be changed depending on the distance of the on-off valve 30, so that the control section 37 that controls the on-off valve 30 via the drive mechanism 31 and the actuator 36 can control the on-off valve 30 during normal driving. By controlling the on-off valve 30 to close and open it during acceleration, a pleasant sound that matches the feeling of driving can be obtained. In addition,
The switching of r# of the on-off valve 30 is not necessarily limited to this example,
The on-off valve 30 may be switched depending on the engine speed, etc., or the on-off valve may be switched manually instead of using the control unit.

Further, each of the above-mentioned tail pipes 5.6 is made replaceable, and various tail pipes 51 to 57 having different acoustic characteristics as shown in FIGS. 10(a) to (9) can be selectively used as required. In this way, the sound quality can be adjusted at will. In these figures, the 10th
The tail pipe 51 in FIG. 10(a) is formed of a straight pipe, the tail pipe 52 in FIG. The tail pipe 54 shown in Fig. 10 (d) has a structure shown in Fig. 10 (C) with a sound-absorbing material between the inner cylinder 54a and the outer cylinder 54b. The tail pipe 55 shown in FIG. 10(e) loaded with 54C is the sound absorbing material 54 in the structure shown in FIG. 10(d).
The tail pipe 56 shown in Fig. 10(f), which is equipped with porous sintered metal 1!55c in place of G, has a thinner inner diameter than the one shown in Fig. 10(d), where the part where the sound absorbing material 56C is loaded is thinner. The tail pipe 57 in Fig. 10 (g) after increasing the size of
The inner gI 57a is tapered and a sound absorbing material is loaded between it and the outer cylinder 57b.

(Effects of the Invention) As described above, the present invention provides a first route having a sound absorbing material type passage as a main part and a second route having an expansion chamber as a main part.
Separate tail pipes are provided in section a, and both of the above paths are communicated upstream of the tail pipe, and an on-off valve is provided on one of the paths upstream from the communication point, so it is possible to have a sufficient noise reduction effect. At the same time, the sound quality can be changed by switching the opening and closing of the above-mentioned on-off valve, and the sound quality can be easily adjusted by selecting the shape etc. of the two tail pipes, eliminating harsh sounds. This makes it possible to provide a desirable sound.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the structure of an exhaust silencer according to an embodiment of the present invention, Fig. 2 is a schematic diagram of the above structure, and Fig. 3 (
a) and (b) are schematic diagrams showing the open and closed states of the on-off valve in a further developed form of the above structure, Fig. 4 is a sectional view showing the driving rock structure of the on-off valve, and Fig. 5 The same side view, FIGS. 6(a) to (C), and FIGS. 7(a) to (C) show the on-off valves when the arrangement of the on-off valves is changed and when the passage structure upstream of the on-off valve is changed. For comparing the sound pressure attenuation effect when the valve is closed, each schematic diagram and characteristic diagram of the sound pressure attenuation amount, Figures 8 (a) to (C) show the case where the passage structure upstream of the on-off valve is changed. In order to compare the sound pressure attenuation effect when the on-off valve is closed, each schematic diagram and the characteristic diagram of the sound pressure attenuation amount are shown. Figure 9 is the characteristic diagram of the sound l when the rM valve is opened and when the valve is closed. , FIGS. 10(a) to 10(i) are sectional views showing various modifications of the tail pipe. 3... First path, 4... Second path, 5, 6... Tail pipe, 7.8... Sound absorbing material, 11-13 expansion chamber,
25...Communication path, 30...Opening/closing valve. Patent applicant: Umex Co., Ltd.
Agent of Ntsuda Co., Ltd.
Patent Attorney Etsushi Kotani Patent Attorney
1) Masamukai Patent Attorney Yasuo Itaya No. 1 Fig. 2 Fig. 3 (a) (b) Fig. 4 (a) Drifting (b) 1 Fig. 16 Hill 1C- No. (a) (b) No. (a) (b) Figure 7 (C) (C)

Claims (1)

[Claims] 1.Equipped with a first path whose main part is a sound-absorbing material type passage having a sound-absorbing material, and a second path whose main part is an expansion chamber, and a tail pipe is provided individually at the end of each of these paths. An exhaust silencer for an engine, characterized in that a communication path is provided upstream of a tail pipe to communicate the two paths, and an on-off valve is provided in one of the paths upstream of the communication point by the communication path.