JPH03168311A - Expansion type muffler - Google Patents

Abstract

PURPOSE:To reduce exhaust pressure and to improve muffling effect without changing the diameters of a muffler body and of a communicating pipe by providing plural branch flow routes in parallel in the muffler body. CONSTITUTION:A communicating pipe 13 for introducing an exhaust gas is connected to a drum-shaped muffler body 11. The first expansion chamber 18 where the exhaust gas introduced through the pipe 13 is expandedly muffled is provided in the muffler body 11. Communicating holes 19, which communicate with the first expansion chamber 18 in parallel and branch the exhaust gas expandedly muffled there into plural flows to guide them, and a bypass pipe 20 are provided. Thus, a branch flow route to load the exhaust gas from the first expansion chamber 18 in order of the communicating hole 19 - the second expansion chamber 21 - the third expansion chamber 22 and a branch flow route to load the exhaust gas in order of the bypass pipe 20 - the third expansion chamber 22 are formed in parallel to each other. The flow of the exhaust gas therefore becomes smooth for performing muffling work without increasing the exhaust pressure.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a muffler that muffles exhaust gas emitted from an engine and then discharges it to the outside. This relates to an expansion type muffler that is once expanded (inflated) and produces rT'1 sound.

(Prior Art) An exhaust system connected to an engine body includes an exhaust manifold, an exhaust pipe, and a muffler. The exhaust manifold has the function of collecting exhaust gas generated by the combustion action on the mixture of fuel and combustion air in the engine body and sending it to the exhaust pipe, and the exhaust pipe connects the exhaust manifold and the muffler. It is a connecting pipe.

The exhaust gas discharged from the engine body is high temperature and high pressure, so if it is released into the atmosphere as it is, it will rapidly expand and make an explosive noise. Therefore, the muffler has the function of gradually expanding the exhaust gas inside the muffler, weakening the exhaust noise, cooling it, and discharging it into the atmosphere via the tail pipe.

To further explain the muffler mentioned above, it reflects the sound waves that enter the muffler body on the exhaust gas from wall to wall on the inner surface, and as they move back and forth, they interfere with each other and gradually lose their power. It is now possible to therefore,
It is true that the muffler's silencing effect increases as the interior becomes more complex, but if it collides with some of the reflected sound waves or the expanded gas is squeezed again, it creates resistance and outputs increases. Therefore, there is a difficult problem of combining the contradictory functions of minimizing resistance and making noise as low as possible.

By the way, the muffler mentioned above has two basic structures: a resonant type that applies the phenomenon of JI-sound attenuation, and an expansion type (also called an expansion type) that has an expansion chamber (also called an expansion chamber) in the middle of the pipe.
8! Generally, sound absorbing materials are provided for each category.

As an example of the above expanded type, for example,
There is a silencer disclosed in Publication No. 716. This is the second
As shown in the figure, the inside of the outer cylinder 1 is partitioned by a plurality of partition plates 2 and 3, communicating holes 4 and 5 are provided in these partition plates 2 and 3 with a phase difference of H, and a large number of holes 7 are provided.・・・． 9・
Exhaust gas inlet pipe 6 and outlet pipe 8 with...
are closed by contacting the partition wall plate 2.3, and the communication holes 4, 5 are formed in the partition wall on the side of the outlet pipe 8 and communicate with the outlet pipe 8.
A tuning hole 10 having a smaller diameter than that shown in FIG.

Exhaust gas produced by the engine body is guided to the introduction pipe 6 via an exhaust mandold and an exhaust pipe (none of which are shown), and exhaust noise is reduced within the outer cylinder 1 by expansion and resistance. At the same time, on the outlet pipe 8 side, the sound that has passed through the communication hole 5 of the partition wall 3 and entered the outlet pipe 8 through the numerous holes 9, and the sound that has entered the outlet pipe 8 through the tuning hole 10 are They interfere with each other and further attenuate the sound.

Alternatively, there is also a silencer as shown in Japanese Utility Model Application Publication No. 62-158113. In any case, what these mufflers have in common is that the exhaust gas introduced into the muffler body (outer cylinder) is successively guided into an expansion chamber, which is a space chamber formed within the muffler body, to expand the muffler's silence. The action is repeated until it is finally discharged to the outside. In other words, it is similar to arranging a plurality of expansion chambers in series within the muffler body and repeatedly guiding the expansion silencing action.

(Problem to be Solved by the Invention) However, in a silencer configured in this manner, the exhaust gas flows sequentially into each expansion chamber arranged in series, so for example, one expansion chamber If it becomes difficult to flow, the overall smooth flow will be obstructed, and as a result, the so-called exhaust pressure will increase, leading to loss of compression work of the engine, resulting in poor running performance.

By the way, in such an expansion type muffler, the higher the expansion rate, the higher the /l! It is known that one sound has a great effect. The expansion ratio is the area ratio between the muffler body and the conduction pipe, which is determined from the muffler body inner diameter/conduction pipe inner diameter. Therefore, in order to increase the expansion rate, it is conceivable to reduce the diameter of the conduction pipe while leaving the diameter of the muffler body unchanged, or to increase the diameter of the muffler body while leaving the diameter of the conduction pipe unchanged.

However, since the conduction pipe communicates directly with the engine body via an exhaust pipe or the like, reducing its diameter may further increase the exhaust pressure and deteriorate driving performance. If the diameter of the muffler main body is increased, since it is attached along the lower surface of the body, the distance from the ground becomes narrower, the ground clearance deteriorates, and it becomes difficult to secure the necessary space. In any case, a configuration that increases the expansion rate cannot be obtained.

The present invention has been made in view of the above circumstances, and aims to reduce exhaust pressure by smoothing the flow of exhaust gas without changing the diameters of the muffler body and the conduction pipe, as well as increasing the expansion ratio. The purpose of the present invention is to provide an expandable muffler that can improve the silencing effect.

[Structure of the invention]

(Means for Solving the Problems) The present invention has a drum-shaped muffler body connected to a conduction pipe for introducing exhaust gas, and a first expansion chamber for expanding and muffling the exhaust gas introduced through the conduction pipe. A plurality of branch flow paths are provided in the muffler main body, communicate in parallel with the first expansion chamber, and divide and guide the expanded and muffled exhaust gas into a plurality of streams to expand and muffle the sound. It is an expansion type muffler.

Further, the branch flow path of the present invention guides a part of the exhaust gas that has been expanded and muffled in the first expansion chamber to a second expansion chamber adjacent to the first expansion chamber through one or more communication holes. a system line for expanding and silencing the noise by expanding the exhaust gas in the first expansion chamber, and bypassing the second expansion chamber through one or more bypass pipes so that the remaining exhaust gas that has been expanded and silenced in the first expansion chamber is adjacent to the second expansion chamber. This is a system that leads to the third expansion chamber to expand and muffle the noise, and the total area of the communication holes is equal to 1 of the area of the conduction pipe.
2, and the total pipe area of the bypass pipe is set to 172 of the conducting pipe area.

Furthermore, the branch flow path of the present invention transfers a part of the exhaust gas that has been expanded and muffled in the first expansion chamber to the second expansion chamber adjacent to the first expansion chamber through one or more communication holes. a system for guiding the exhaust gas to a third expansion chamber adjacent to the second expansion chamber, and one or more bypass pipes for discharging the remaining exhaust gas expanded in the first expansion chamber. This is a system path that directly guides the exhaust gas to the third expansion chamber for expansion and silencing, as well as interfering with the exhaust gas led from the second expansion chamber. The expandable muffler according to claim 11 is characterized in that the muffler is introduced into an adjacent fourth expansion chamber, expanded, and then discharged to the outside.

(Function) Exhaust gas guided into the muffler body from the conduction pipe is once expanded and muffled in the first expansion chamber, and then divided into a plurality of branch flow paths communicating in parallel with the first expansion chamber. Since the exhaust gas is expanded and muffled in the diversion system before being discharged to the outside, the flow of the exhaust gas is smooth and the sound muffling effect is achieved without increasing the exhaust pressure.

The total area of the communication hole is set to 172 of the area of the conduction pipe, and the total area of the bypass pipe is set to 1/2 of the area of the conduction pipe, so the sum of the areas of the communication hole and the bypass pipe is equal to the area of the conduction pipe. The exhaust gas led from the conduction pipe is led to the system between the communication hole and the bypass pipe without being stagnant in the expansion chamber of T51. Furthermore, in each system, the expansion ratio for the exhaust gas is substantially doubled due to the above-mentioned area relationship, and the noise reduction effect is improved without changing the area of the muffler body and the conduction pipe.

and a system path that guides a part of the exhaust gas that has been expanded and muffled in the first expansion chamber to the second expansion chamber via the communication hole, expands and muffles the exhaust gas, and then leads it to the third expansion chamber; The remaining exhaust gas that has been expanded and muffled in the chamber is directly guided to a third expansion chamber via a bypass pipe and divided into a system for expansion, and in this third expansion chamber, the exhaust gas guided through each system is mutually divided. let me interfere,
From here, all the exhaust gas is led to the fourth expansion chamber where it is expanded and muffled before being discharged to the outside, so that the exhaust gas is completely muffled.

(Embodiment) An embodiment of the present invention will be described below based on FIG. 1. In the figure, reference numeral 11 denotes a drum-shaped muffler body whose both end surfaces are closed, and a sound absorbing material 12 such as glass wool is adhered to the both end closed surfaces and the peripheral surface. A conduction pipe 13 passes through both end surfaces of this muffler body l1 along the axial direction. The diameters of the conduction pipe 13 and the muffler body 11 are basically the same as those of the conventional one,
Therefore, the area of the conduction pipe l3 and the muffler body 11
There is no difference in both the product and the product. In the figure, conduction pipe 1
The left end of No. 3 communicates with the engine body via an exhaust pipe and exhaust manifold (not shown), and the right end communicates with a tail pipe (not shown).

Further, a pair of closing plates 14a and 14b are provided at predetermined positions within the conductive pipe 13 with a predetermined interval therebetween to close the inside of the pipe 13. Furthermore, a large number of small holes 15 . . . are bored in the conduction pipe 13 .

These small holes 15... consist of a plurality of small hole groups 16a to 16e that are arranged in a group and are spaced apart from each other by a predetermined distance.

On the other hand, first to third partition plates 17a to 17c are provided inside the muffler main body 11 at different intervals from each other, and partition the space between the muffler body 11 and the outer circumferential surface of the conductive pipe 13 into a plurality of chambers. The first recessed wall plate 17a is the one blocking plate 14
A chamber located at a position substantially corresponding to a and surrounded by one end surface of the muffler wooden body 11 and the first partition plate 17a is referred to as a first expansion chamber 18. The small hole group 16a communicates with this first expansion chamber 18. Further, in the first partition plate 17a, a plurality of communication holes and a plurality of bypass pipes 20 are provided every other (for example, three) concentrically. The bypass pipe 20 is constructed so as to pass through the second partition plate 17b. In addition, the total hole area of the communication hole 19 is assumed to be 172 of the pipe area of the conduction pipe 13, and the bypass pipe 2
The total pipe area of 0 is set to be 1/2 of the pipe area of the conduction pipe 13. The chamber surrounded by the first partition plate 17a, the second partition plate 17b, and the muffler body 11 is referred to as a second expansion chamber 21, and the small hole group 16b also communicates with this chamber.

The chamber surrounded by the second partition plate 17b, the third partition plate 17c, and the muffler main body 11 is referred to as a third expansion chamber 22, and the small hole group 16c also communicates with this chamber. Since the opening at the other end of the bypass pipe 20 passes through the second partition plate 17b, the bypass pipe 20 directly communicates between the first expansion chamber 18 and the third expansion chamber 22. 21 will be bypassed.

The chamber surrounded by the third partition plate 17c and the other end surface of the muffler body 11 is called a fourth expansion chamber 23, and the small hole groups 16d and 16e on both sides of the closing plate 14b communicate with this chamber.

In this way, inside the muffler body 11, there are expansion chambers @1 to fourth expansion chambers 18, 2 extending from the exhaust gas inlet side to the exhaust gas outlet side.
1, 22, and 23 are arranged in sequence, and the above-mentioned through holes]9
From the position where the bypass pipe 20 is provided, the first expansion chamber 18, the communication hole 19, the second expansion chamber 21, and the third expansion chamber 22
A branch flow path that guides the exhaust gas in the order of and the first expansion chamber 18-
The bypass pipe 20 and the branch flow path that guide the exhaust gas in the order of the third expansion chamber 22 are arranged in parallel with each other.

Exhaust gas discharged from the engine body is guided to this muffler via the exhaust manifold and exhaust pipe. The exhaust gas guided through the conduction pipe 13 collides with the blockage 14a and is guided from the small hole group 16a in front of this to the first expansion chamber 18, where it expands and performs the first stage of silencing action. .

Next, a part of the exhaust gas expanded in the first expansion chamber 18 is guided to the second expansion chamber 21 through one of the plurality of communication holes, where it is expanded and subjected to a second stage of silencing effect. will be done. On the other hand, the remaining exhaust gas that has been expanded and muffled in the first expansion chamber 18 is led directly to the third expansion chamber 22 via a plurality of bypass pipes 20, and is expanded here to perform the second stage of muffling. This is done in the same way as the second expansion chamber 21 described above.

In other words, the exhaust gas is divided from the first expansion chamber 18 into the two branch flow paths provided in parallel to achieve a muffling effect, so that the muffling effect is improved without increasing the exhaust pressure. Then, the total hole area of the communication holes 19 is set to 1 of the pipe area of the conduction pipe 13.
/2, and the total pipe area of the binox pipe 20 is the conduction pipe 1.
3, the total area of the communication holes 19 and the bypass pipe 20 is the same as the area of the conduction pipe 13, and approximately half of the exhaust gas is removed from the first expansion chamber 18. is very smoothly diverted to the second expansion chamber 21 or directly to the third expansion chamber 22, resulting in a reduction in discharge.

Also, the total hole area of the communication hole 19 is determined by the above-mentioned conduction pipe 1
3, and the total area of the bypass pipe 20 was set to 1/2 of the pipe area of the conduction pipe 13. Therefore, the expansion ratio for the exhaust gas flowing through these communication holes 19 and the binoculars pipe 20 is are substantially doubled, without changing the areas of the muffler body 11 and the conduction pipe 13.
Improves sound deadening effect.

The exhaust gas guided from the second expansion chamber 21 to the third expansion chamber 22 and the exhaust gas directly guided to the third expansion chamber 22 interfere with each other in the third expansion chamber 22. It also acts as a silencing effect. All exhaust gases are transferred to the third expansion chamber 2
2 to the fourth expansion chamber 23 for expansion silencing.

Since the closing plate 14b that partitions the inside of the conductive pipe 13 is located in the fourth expansion chamber 23, it is substantially the same as expanding in two stages. As a result, the exhaust gas divided in the first expansion chamber 18 is led out from the muffler body 11 in a substantially completely muffled state.

〔Effect of the invention〕

As described above, according to the present invention, since a plurality of branch flow paths are provided in parallel within the muffler main body, the flow of exhaust gas is smooth, the exhaust pressure is reduced, and running performance can be improved. In addition, the expansion ratio for the exhaust gas in each branch flow path is substantially doubled, and effects such as almost complete noise reduction can be achieved without changing the areas of the muffler body and the conduction pipe.

[Brief explanation of the drawing]

FIG. 1 is a schematic longitudinal cross-sectional view of an expandable muffler showing an embodiment of the present invention, and FIG. 2 is a schematic vertical cross-sectional view of an expandable muffler showing a conventional example of the present invention. 11... Muffler body, 13... Continuity pipe, l8.
...First expansion chamber, 19...Communication hole, 21...Second
expansion chamber, 20... bypass pipe, 22... third expansion chamber, 23... fourth expansion chamber.

Claims (3)

[Claims] (1) A conduction pipe that introduces exhaust gas into the drum-shaped muffler body, a first expansion chamber provided in the muffler body that expands and muffles the exhaust gas introduced through the conduction pipe, and this first expansion chamber. An expandable muffler characterized by comprising a plurality of branch flow paths communicating in parallel with a chamber and expanding and silencing the exhaust gas by dividing and guiding it into a plurality of streams. (2) The branch flow path guides a part of the exhaust gas that has been expanded and muffled in the first expansion chamber to a second expansion chamber adjacent to the first expansion chamber through one or more communication holes. The remaining exhaust gas that has been expanded and silenced in the first expansion chamber is bypassed through the second expansion chamber through one or more bypass pipes, and is connected to a second expansion chamber adjacent to the second expansion chamber. 3
It is a system line that leads to an expansion chamber and expands and silences the sound, and the total area of the communication holes is set to be 1/2 of the area of the above-mentioned conduction pipe, and the total area of the bypass pipe is set to be 1/2 of the area of the conduction pipe. An expandable muffler according to claim 1, characterized in that: (3) The branch flow path guides a part of the exhaust gas that has been expanded and muffled in the first expansion chamber to a second expansion chamber adjacent to the first expansion chamber through one or more communication holes. After expanding and silencing the exhaust gas, the remaining exhaust gas expanded in the first expansion chamber is passed through a line leading to a third expansion chamber adjacent to the second expansion chamber, and one or more bypass pipes. This is a line that leads directly to the third expansion chamber for expansion and silencing and also interferes with the exhaust gas guided from the second expansion chamber, and is adjacent to the third expansion chamber for expansion and silencing. The expandable muffler according to claim 1, further comprising a fourth expansion chamber that guides all the exhaust gases, expands and muffles them, and then discharges them to the outside.