JP3511779B2 - Engine exhaust silencer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an engine exhaust muffler that reduces noise generated from an exhaust pipe of an automobile or the like.

[0002]

2. Description of the Related Art As conventional exhaust muffler for automobiles,
It has been proposed to reduce the exhaust noise in the low rotation range of the engine as well as to reduce the exhaust noise in the middle and high rotation range, for example, Japanese Patent Laid-Open No. 64-64-
The one disclosed in Japanese Patent No. 60709 is known.

This is provided with a first exhaust passage that emphasizes reduction of exhaust noise in the low engine speed range and a second exhaust passage that emphasizes reduction of exhaust noise in the middle and high engine speed range of the engine. In the muffler, while the control valve installed in the second exhaust passage is closed in the low engine speed range,
The valve is opened in the high speed range, and exhaust is performed only in the first exhaust passage in the low speed range, while it is exhausted in the high speed range by the first and second exhaust passages. Increase) while suppressing noise.

However, in such a conventional device, since the control valve is driven by a motor or the like according to the number of revolutions of the engine, a control means is required, which complicates the entire device and increases the manufacturing cost. There is a problem.

In response to this, the applicant of the present invention filed Japanese Patent Application No.
The one proposed as No. -96336 is provided with an exhaust pressure sensing valve means for opening the second exhaust passage in response to the exhaust pressure of the engine inside the muffler.

Exhaust gas discharged from the engine is discharged through the first exhaust passage in the low speed region to reduce the exhaust noise in the low speed region, while the valve opens in response to the exhaust pressure in the high speed region. The valve is exhausted through the first exhaust passage and the second exhaust passage, and exhaust noise is reduced while suppressing exhaust loss in a high rotation range.

Since the valve has a structure for opening and closing the second exhaust passage against the return spring, a motor or the like is not required and the structure can be simplified and the manufacturing cost can be reduced.

[0008]

However, in the conventional device in which the return spring is provided inside the muffler, the return spring is exposed to high temperature exhaust gas, so that the heat resistance required for the return spring is high and the cost is high. There is a problem in that it is necessary to use a different heat-resistant alloy material, resulting in an increase in product cost.

Therefore, the present invention has been made in view of the above-mentioned problems, and it is possible to suppress the decrease in the output while ensuring the silencing performance in the entire engine revolution range and to suppress the increase in the manufacturing cost of the engine exhaust gas. An object is to provide a silencer.

[0010]

An exhaust muffler for an engine according to a first aspect of the present invention includes a muffler for reducing exhaust noise of the engine, a first tail tube for exhausting exhaust gas guided from the engine to the muffler to the outside, and An exhaust gas muffler for an engine, comprising: a second tail tube; and an exhaust pressure sensing valve means for opening the second tail tube in response to an engine exhaust pressure generated inside the muffler. as provided provided in the opening end against the outside of the second tail tube, and a valve for opening and closing the open end, and a return spring for pressing the valve to the open end of the second tail tube, the.

According to a second aspect of the present invention, there is provided an exhaust muffler for an engine according to the first aspect, further comprising a cylindrical finisher for covering an open end of the tail tube to the outside, and a valve and a return spring for the finisher. Place it inside.

According to a third aspect of the present invention, there is provided an exhaust silencer for an engine according to the second aspect, wherein an inner pipe fitted to the tail tube is provided inside the finisher, and a valve is provided in the inner pipe via a return spring. Coupling is possible.

An exhaust muffler for an engine according to a fourth aspect of the present invention is the exhaust gas silencer according to any one of the first to third aspects, further comprising two valves rotatably supported via the return spring. The turning ends of the valves are opposed to each other with the passage center of the tail tube interposed therebetween.

[0014]

In the exhaust muffler for an engine according to claim 1, the exhaust gas discharged from the engine is discharged through the first tail tube in the low speed region to reduce the exhaust noise in the low speed region. Exhaust is discharged through the first tail tube and the second tail tube in the high rotation range where the valve opens, and exhaust noise is reduced while suppressing exhaust loss in the high rotation range.

Since the valve has a structure for opening and closing the second tail tube against the return spring, a motor or the like is not required and the structure can be simplified, and the manufacturing cost can be reduced.

By providing the valve at the open end of the tail tube, the return spring is not exposed to high-temperature exhaust gas inside the muffler, the temperature of the return spring is kept low, and the spring constant of the return spring is kept proper for a long period of time. Can be maintained at.

As a result, the heat resistance required for the return spring is lowered, it is not necessary to use an expensive heat resistant alloy material, and the cost of the product can be reduced.

In the engine exhaust silencer according to the second aspect of the present invention, the valve and the return spring are covered with the cylindrical finisher to protect them and improve the appearance.

In the exhaust muffler for an engine according to a third aspect of the present invention, the structure is such that the valve is rotatably coupled to the inner pipe fitted to the tail tube via the return spring, and the return spring together with the finisher via the inner pipe. And since the valve is unitized and attached to the tail tube, productivity can be improved.

In the engine exhaust silencer according to the fourth aspect of the present invention, since the rotating ends of the valves are opposed to each other with the passage center of the tail tube interposed therebetween, the open end of the tail tube is formed by the passage center of each valve. The region including is opened, and the exhaust gas flows through the central portion of the passage of the tail tube, so that the air flow noise is reduced.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, baffle plates 6, 7 and 8 are arranged in the radial direction of the ellipse on the inner circumference of a muffler 1 for an automobile having a substantially elliptical cross section. These baffle plates 6, 7 and 8 respectively define chambers 4, 3, 2 and 5 at positions adjacent to each other from the left side in FIG.

Exhaust from an engine (not shown) is a muffler 1.
The inlet tube 9 serving as an exhaust gas introduction conduit that leads to is opened to the chamber 3 after penetrating the chamber 4, and the exhaust gas from the engine is guided to the chamber 3.

The chamber 3 and the chamber 4 communicate with each other through a pass tube 10 which penetrates the baffle plate 6. The chamber 3 and the chamber 5 communicate with each other via a pass tube 11 that penetrates the baffle plates 7 and 8. The chamber 5 and the chamber 2 communicate with each other through a pass tube 12 that penetrates the baffle plate 8.

A first tail tube 12 that communicates with the outside communicates with the chamber 4. The tail tube 12 has a predetermined diameter and length that place importance on reducing exhaust noise in the low engine speed region.

As a first sound deadening means, the chambers 3 and 4 act as expansion elements, and the chambers 5 and 2 act as resonance chambers of the resonator via the pass tubes 11 and 12, whereby exhaust gas in the low engine speed region is exhausted. Reduce noise.

The chamber 5 and the chamber 2 constitute a second silencing means with a predetermined capacity that places importance on reducing exhaust noise in the high engine speed region.

A second tail tube 13 communicating with the outside is opened in the chamber 2. The tail tube 13 projects in parallel with the tail tube 12 to the outside of the muffler 1. The tail tube 13 has a predetermined diameter and length that place importance on reducing exhaust noise in the high engine speed range.

The exhaust gas is also silenced through the sound absorbing material 36 while passing through each tail tube 13. Each tail tube 1
A large number of holes 35 are opened in the middle of the holes 2 and 13, a sound absorbing material 36 is provided on the outer periphery of these holes 35, and an outer cylinder 37 is provided so as to cover the outside of the sound absorbing material 36.

Cylindrical finishers 22 and 23 are attached to the open ends of the tail tubes 12 and 13 to the outside, respectively.

As shown in FIG. 2, the finisher 23
A cylindrical inner sleeve 25 that fits around the outer periphery of the tail tube 13 is provided inside the. As shown in FIG. 3, the finisher 23 is supported by the inner sleeve 25 via three brackets 26. The finisher 23 covers the open end of the tail tube 13 to protect the tail tube 13 and improve its appearance.

A valve 16 is provided at an open end of the tail tube 13 as an exhaust pressure sensitive valve means for opening the second tail tube 13 in response to engine exhaust pressure generated inside the muffler 1.

The valve 16 is formed in a disc shape. The inner sleeve 25 has a seat portion 2 on which the valve 16 is seated.
8 is formed in a ring shape.

A return spring 17 for pressing the valve 16 against the seat portion 28 is provided. The valve 16 is rotatably supported via a return spring 17.

The shaft 15 is fixed to the inner sleeve 25. A pair of coil-shaped return springs 17 are inserted through the shaft 15. One end of each return spring 17 is fixed to the valve 16. Return spring 17
The other end of is engaged with the outer circumference of the inner sleeve 25 as described above. Next, the operation will be described.

Exhaust gas from the engine first flows into the chamber 3 via the inlet tube 9. Since the exhaust pressure is low in the low engine speed region, the valve 16 biased by the return spring 17 does not open, and the exhaust gas of the chamber 3 flows into the chamber 4 via the pass tube 10 and the tail tube 12
Is discharged to the outside.

Since the chambers 3 and 4 as the first silencing means are provided with a predetermined capacity corresponding to the low rotation range as the expansion element,
Exhaust pulsating component that synchronizes with engine speed
Exhaust noise is reduced by being attenuated when passing through.

Similarly, the chambers 5 and 2 as the first muffling means have a predetermined capacity according to the low rotation range, and the pass tubes 11 and 12 have a predetermined cross-sectional area and length according to the low rotation range. Therefore, the spaces of the chambers 5 and 2 function as the resonance chamber of the resonator, and the pulsating component of the exhaust gas that is synchronized with the engine speed is attenuated. As a result, it is possible to improve the muffling performance in the low rotation range of the engine having a low exhaust flow rate.

On the other hand, the exhaust pressure flowing from the inlet tube 9 increases in the high engine speed range, and when the internal pressure of the muffler 1 exceeds a predetermined value, the valve 16 opens against the return spring 17.

When the valve 16 is opened, the exhaust gas flowing into the muffler 1 is discharged to the outside from the tail tube 12 through the chamber 3, the pass tube 10 and the chamber 4 in the same manner as in the above low rotation range, and It is also discharged from the tail tube 13 via the pass tube 11, the chamber 5, the pass tube 12, and the chamber 2 as the sound deadening means. Since the chambers 5 and 2 are provided with a predetermined volume corresponding to a high rotation range as an expansion element, the chamber 3
The noise of the high frequency component contained in the exhaust gas that has flowed in through the pass tube 11 is attenuated.

In this way, the area of the exhaust gas discharged from the muffler 1 is equal to enlarging the diameter of the exhaust passage because the sectional area of the tail tube 13 is added to the sectional area of the tail tube 12. It is possible to reduce exhaust loss (increase in exhaust pressure) in an increasing high rotation range to suppress a decrease in engine output, and also to reduce exhaust gas noise.

In this way, since the valve 16 is opened and closed according to the pressure of the exhaust gas, the motor and its control means are not required to open and close the valve 16,
Product cost can be reduced by simplifying the structure.

A valve 16 is fitted to an inner pipe 25 fitted to the tail tube 13 via a return spring 17.
The structure that rotatably connects the inner pipe 25
Since the return spring 17 and the valve 16 are unitized together with the finisher 23 and attached to the tail tube 13 via the, the productivity can be improved.

Since the valve 16 is provided at the open end of the tail tube 13 with respect to the outside, the temperature of the return spring 17 is kept low and the spring constant of the return spring 17 is maintained for a long period of time as compared with the structure provided inside the muffler 1. It can be maintained properly.

As a result, the heat resistance required for the return spring 17 is lowered, it is not necessary to use an expensive heat resistant alloy material, and the cost of the product can be reduced.

Further, the finisher 23 covers the valve 16 and the return spring 17 and the like to protect them and improve the appearance.

Next, the embodiment shown in FIGS. 4 and 5 will be described. The parts corresponding to those in FIGS. 2 and 3 are designated by the same reference numerals.

A pair of valves 44 and 46 are provided at the open end of the tail tube 13 as an exhaust pressure sensitive valve means for opening the second tail tube 13 in response to engine exhaust pressure generated inside the muffler 1. To be

Each of the valves 44 and 46 is formed in a semicircular plate shape. The valves 44 and 46 are joined to each other while seated on the seat portion 28 to close the tail tube 13. The portion where the valves 44 and 46 are joined to each other is formed in a linear shape that bisects the open end of the tail tube 13. That is, the rotating ends of the valves 44 and 46 are opposed to each other with the passage center of the tail tube 13 interposed therebetween.

Return springs 45, 47 for pressing the valves 44, 46 against the annular seat portion 28 are provided. Each valve 44, 46 is rotatably supported via each return spring 45, 47.

With the above construction, the operation will be described below.

When the exhaust pressure increases in the high engine speed range, the valves 44 and 46 open against the return springs 45 and 47.

At this time, the open end of the tail tube 13 is opened in a region including the passage center by the valves 44 and 46, so that the exhaust gas flows in the center portion of the passage of the tail tube 13 to reduce the air flow noise.

[0054]

As described above, in the engine exhaust muffler of the first aspect, the return spring is provided with a valve responsive to the exhaust pressure at the open end of the tail tube so that the return spring has a high temperature exhaust inside the muffler. The temperature of the return spring is kept low, the heat resistance required for the return spring is low, the need for using an expensive heat-resistant alloy material is eliminated, and the cost of the product can be reduced.

In the engine exhaust muffler according to the second aspect, the valve and the return spring are covered by the cylindrical finisher to protect them and improve the appearance.

In the engine exhaust muffler according to the third aspect, the valve is rotatably coupled to the inner pipe fitted to the tail tube via the return spring, and the return spring is provided together with the finisher via the inner pipe. And since the valve is unitized and attached to the tail tube, productivity can be improved.

In the exhaust muffler for an engine according to the fourth aspect of the present invention, since the turning ends of the valves are opposed to each other with the passage center of the tail tube interposed therebetween, the opening end of the tail tube is provided with the passage center of each valve. The area containing
Exhaust gas flows through the center of the passage of the tail tube, reducing air flow noise.

[Brief description of drawings]

FIG. 1 is a sectional view of a muffler showing an embodiment of the present invention.

FIG. 2 is a sectional view of a valve and the like.

FIG. 3 is a sectional view taken along line XX of FIG.

FIG. 4 is a cross-sectional view of a valve and the like showing another embodiment.

FIG. 5 is a sectional view taken along line XX of FIG.

[Explanation of symbols] 1 muffler 2 rooms 3 rooms 4 rooms 5 rooms 6 baffle plate 7 baffle plate 8 baffle plate 12 tail tubes 13 tail tube 16 valves 17 Return spring 23 Finisher 25 Inner pipe 44 valves 45 Return spring 46 valves 47 Return spring

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Claims (4)

(57) [Claims] 1. A muffler for reducing exhaust noise of an engine, a first tail tube and a second tail tube for exhausting exhaust gas introduced from the engine to the muffler, and an exhaust pressure of the engine generated inside the muffler. An exhaust pressure muffler for an engine, comprising: an exhaust pressure sensitive valve means for responsively opening the second tail tube, wherein the exhaust pressure sensitive valve means is provided at an open end of the second tail tube to the outside.
An exhaust muffler for an engine , comprising: a valve that opens and closes the opening end; and a return spring that presses the valve against the opening end of the second tail tube. 2. An exhaust muffler for an engine according to claim 1, further comprising a cylindrical finisher for covering an opening end of the tail tube to the outside, wherein the valve and the return spring are arranged inside the finisher. . 3. The engine according to claim 2, wherein an inner pipe fitted to the tail tube is provided inside the finisher, and a valve is rotatably coupled to the inner pipe via a return spring. Exhaust silencer. 4. A valve comprising two valves that are rotatably supported by the return spring, and the turning ends of the valves are opposed to each other with a passage center of the tail tube interposed therebetween. An engine exhaust muffler according to any one of 1 to 3.