JP3163957B2 - 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 silencer for reducing noise generated from an exhaust pipe of an automobile or the like.

[0002]

2. Description of the Related Art Conventional exhaust silencers for automobiles include:
Japanese Patent Application Laid-Open No. 64-64 proposes a technique that reduces exhaust noise in the low engine speed range while also reducing exhaust loss in the middle and high engine speed ranges.
One disclosed in Japanese Patent No. 60709 is known.

[0003] This is provided with a first exhaust passage emphasizing reduction of exhaust noise in a low engine speed region and a second exhaust passage emphasizing reduction of exhaust noise in a high engine speed region of the engine. In the muffler, the control valve interposed in the second exhaust passage is closed in a low engine speed range,
The valve opens in the middle and high speed ranges. In the low speed range, exhaust is performed only through the first exhaust passage, while in the high speed range, exhaust is performed through the first and second exhaust passages. (Increase of pressure) while suppressing noise.

As disclosed in Japanese Utility Model Laid-Open No. 57-13832, the exhaust chamber of a two-stroke engine is divided into two chambers by a baffle plate, and two tubes provided on the baffle plate are used. It is known to improve the output in the middle / high rotation range while securing the output at low speed by providing a reed valve that opens and closes according to the pressure of exhaust gas in one tube by connecting the respective chambers. .

[0005]

However, in the case of the former device, since the control valve is driven by a motor or the like in accordance with the number of revolutions of the engine, control means is required and the whole device becomes complicated. At the same time, there is a problem that the manufacturing cost is increased.

In the latter device, since the cross-sectional area of the exhaust passage is constant regardless of whether the reed valve is open or closed, the expansion ratio with respect to the chamber cannot be set large.
In order to reduce exhaust noise, it is necessary to increase the volume of the chamber, which not only leads to an increase in the size of the device, but also makes it impossible to set a large expansion ratio, thereby sufficiently suppressing the airflow noise generated from the reed valve. Therefore, there is a problem that the exhaust noise may not be reliably reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made in consideration of the above problems. An object of the present invention is to provide a silencer.

[0008]

According to a first aspect of the present invention, there is provided a muffler for reducing exhaust noise of an engine, a first exhaust passage for discharging exhaust gas guided from the engine to the muffler, and a first exhaust passage. An exhaust silencer for an engine, comprising: a second exhaust passage, and valve means for opening the second exhaust passage in response to an exhaust pressure of the engine generated inside the muffler, wherein two chambers are provided as the valve means. A through hole opened in the baffle plate to be defined, a pass tube inserted through the through hole with a gap to define the second exhaust passage, a valve slidably fitted in the pass tube, and a baffle plate A return spring that presses against the side to close the through hole.

According to a second aspect of the present invention, in the exhaust gas muffler for an engine according to the first aspect, an insertion hole is formed in the valve so as to fit into the outer peripheral surface of the pass tube with a gap therebetween. A plurality of guide claws are formed in sliding contact with the outer peripheral surface.

According to a third aspect of the present invention, in the engine exhaust silencer according to the first or second aspect, a cushioning member is interposed between the baffle plate and the valve.

According to a fourth aspect of the present invention, in the engine exhaust silencer according to any one of the first to third aspects, the return spring is formed in a coil shape to be inserted into a pass tube.

According to a fifth aspect of the present invention, there is provided an exhaust muffler for an engine according to any one of the first to fourth aspects, wherein the valve is partitioned by a valve and a baffle plate in a state where the valve closes a through hole. Constitutes a resonance chamber communicating with the second exhaust passage via the pass tube.

[0013]

In the exhaust gas muffler for an engine according to the first aspect, the exhaust gas discharged from the engine is discharged through the first exhaust passage in a low rotation speed region, and the exhaust noise in the low rotation speed region is reduced. The exhaust gas is discharged through the first exhaust passage and the second exhaust passage in a high rotation region where the valve opens, and reduces exhaust noise while suppressing exhaust loss in the middle and high rotation regions.

Since the valve slides the pass tube against the return spring to open and close the second exhaust passage, the structure is simplified without the need for a motor or the like, and the manufacturing cost can be reduced. it can.

Since the valve slides away from the through hole of the baffle plate by sliding the pass tube, the rate of change of the opening area with respect to the amount of expansion and contraction of the return spring is greater than that of a conventional reed valve or the like. , And exhaust loss (increase in exhaust pressure) in a high rotation range is reduced to suppress a decrease in engine output.

The structure in which the valve is fitted to the pass tube can prevent the valve from dropping out of the muffler due to aging.

In the exhaust gas muffler for an engine according to the second aspect, the valve slides on the outer peripheral surface of the pass tube via the plurality of guide claws, thereby reducing the friction of the valve and sliding the valve. In this case, noise can be prevented from being generated.

In the engine exhaust silencer according to the third aspect, the structure in which the cushioning material is interposed between the baffle plate and the valve can prevent generation of noise when the valve is seated on the baffle plate side. .

In the engine exhaust silencer according to the fourth aspect, the return spring is formed in a coil shape that is inserted into the pass tube, thereby simplifying the structure and dropping the return spring from the muffler due to aging. Can be prevented.

Further, when the valve is opened, the coil-shaped return spring is located behind the valve with respect to the flow of exhaust gas, so that the return spring is prevented from being exposed to a high-speed exhaust gas flow. Deterioration can be suppressed.

According to a fifth aspect of the present invention, there is provided an exhaust muffler for an engine according to the fifth aspect of the present invention, wherein a low pressure in the low engine speed range of the engine is provided by a resonator constituted by a pass tube and a chamber partitioned by the valve and the baffle plate with the valve closing the through hole. While effectively reducing frequency noise, exhaust is exhausted through the pass tube in the high engine speed range where the valve opens, reducing exhaust noise while suppressing exhaust loss in the middle and high speed ranges. .

[0022]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, baffle plates 6 and 8 are arranged on the inner periphery of a muffler 1 for a vehicle having a substantially elliptical cross section in the radial direction of the ellipse. These baffle plates 6 and 8 allow the chambers 2 and 2 from the left side in FIG.
3, 4 are sequentially defined at adjacent positions.

Exhaust from an engine (not shown) is
An exhaust gas introduction pipe leading to the chamber 2 communicates with the chamber 2, and exhaust gas from the engine is guided to the chamber 2.

A tail tube 12 as a first exhaust passage communicating with the outside communicates with the chamber 2. The tail tube 12 has a predetermined diameter and length that emphasizes reduction of exhaust noise in a low engine speed range.

The chamber 2 and the chamber 4 communicate with each other via a pass tube 10 penetrating the baffle plate 6.
And the chamber 4 are the pass tubes 1 penetrating the baffle plate 7
1 communicate with each other.

As a first noise reduction means, the resonance chamber 2 functions as an expansion element, and the chamber 4 functions as a resonance chamber of a resonator via a pass tube 10, thereby reducing exhaust noise in a low engine speed range. .

Baffle plates 6 and 8 between chambers 2 and 4
The chamber 3 defined through the above-mentioned structure has a predetermined capacity that emphasizes reduction of exhaust noise in the middle and high speed regions of the engine, and constitutes a second noise reduction unit.

A tail tube 13 is opened in the chamber 3 as a second exhaust passage communicating with the outside. The tail tube 13 projects outside the muffler 1 in parallel with the tail tube 12.

The baffle plate 8 defining the chamber 4 and the chamber 3 has a circular through hole 14 as an exhaust passage communicating with the first and second muffling means.

The pass tube 10 passes through the through hole 14 with a gap. One end of the pass tube 10 is supported by the baffle plate 8 via a stay 17.

A valve 16 for opening and closing the through hole 14 is provided on the chamber 3 side of the baffle plate 8.

As shown in FIG. 2, a disc-shaped valve 16 is formed concentrically with an insertion hole 17 through which the pass tube 10 is inserted.

An annular step 23 is formed concentrically on the valve 16 to secure its rigidity.

Three or more guide claws 22 extend from the inner peripheral edge 21 of the baffle plate 8 where the through hole 14 is opened. Each guide claw 22 connects the valve 16 to the pass tube 1
It has the function of supporting it slidably with respect to zero.

Each guide claw 22 is formed in an arc shape so as to make point contact with the outer peripheral surface 19 of the pass tube 10.

The inner peripheral edge 21 of the valve 16 is formed with a dimensional relationship of clearance so as to have a predetermined gap 25 with respect to the outer peripheral surface 19 of the pass tube 10. The size of the gap 21 is formed as small as possible within a range in which the inner peripheral edge 21 of the valve 16 does not contact the outer peripheral surface 19 of the pass tube 10 in consideration of manufacturing errors. This prevents the gap 25 from deteriorating the muffling effect of the muffler 1 described later.

In the baffle plate 8, an inner peripheral portion 31 defining the insertion hole 17 is bent into a cylindrical shape. Inner edge 3
An annular cushioning member 30 is fitted to the outside of the valve 1 so as to face the valve 16. The cushioning member 30 is formed of a material such as a wire mesh, and reduces shock when the valve 16 is seated.

A return spring 29 for pressing the valve 16 against the cushioning member 30 is provided. The coil-shaped return spring 29 is provided concentrically on the pass tube 10.

A disc-shaped retainer 28 is fixed in the middle of the pass tube 10. Retainer 28 and valve 16
The return spring 29 is interposed in a compressed state, and presses the valve 16 against the cushioning material 30.

One end of the return spring 29 is concentrically held by the pass tube 10 by engaging with the annular step 23 of the valve 16.

The configuration is as described above. Next, the operation will be described.

Exhaust gas from the engine first flows into the chamber 2 via an exhaust gas introduction line. Since the exhaust pressure is low in the low engine speed range, the valve 16 urged by the return spring 28 does not open, and the exhaust gas in the chamber 2 is exhausted from the tail tube 12 to the outside.

Since the chamber 2 as the first silencing means has a predetermined capacity corresponding to the low rotation range as an expansion element, the pulsation component of the exhaust synchronized with the engine speed is attenuated when passing through the chamber 2. By doing so, exhaust noise can be reduced.

Similarly, since the chamber 4 as the first muffling means has a predetermined capacity corresponding to the low rotation range and has a cross-sectional area and a length of the pass tube 10, the chamber 4 is substantially sealed via the valve 16. The space in the chamber 4 functions as a resonance chamber of the resonator, and the pulsating component of the exhaust synchronized with the engine speed is attenuated, thereby reducing the exhaust noise and improving the noise reduction performance of the engine with a low exhaust flow rate in a low rotation range. Can be done.

On the other hand, when the engine speed is in the middle or high speed region, the exhaust pressure flowing from the exhaust gas introduction line increases, and when the internal pressure of the chamber 4 exceeds a predetermined value, the valve 16 opens against the return spring 28. .

The exhaust gas which has flowed into the muffler 1 is discharged from the tail tube 12 to the outside through the chamber 2 in the same manner as in the low-speed region, and also from the pass tube 10 as indicated by an arrow in FIG. The air is also discharged from the tail tube 13 through the chambers 4 and 3 serving as the air conditioner. Thus, the duct area of the exhaust gas discharged from the muffler 1 is reduced by the tail tube 12.
Since the cross-sectional area of the tail tube 13 is added to the cross-sectional area of
Exhaust loss (increase in exhaust pressure) in the middle and high speed regions where the exhaust flow rate increases, equivalent to increasing the diameter of the exhaust passage
And the reduction in engine output can be suppressed, and the airflow noise of exhaust gas can be reduced.

Since the chambers 4 and 3 have a predetermined volume corresponding to the middle and high speed regions as expansion elements, noise of high frequency components contained in exhaust gas flowing from the chamber 2 through the pass tube 10 is reduced. As a result, the exhaust noise can be reduced, and the exhaust noise can be reliably reduced even in the middle and high rotation ranges.

In this manner, the valve 16 that opens and closes in accordance with the rotation range of the engine is connected to the through hole 1 that connects the chamber 4 to the chamber 3.
4, the chamber 5 for silencing in the middle and high rotation ranges according to the pressure of exhaust gas and the tail tube 13 are selectively communicated with the chamber 2. Therefore, the expansion action in the chamber 2 in the low rotation range of the engine. And the resonance action in the chamber 4 via the pass tube 10 effectively suppresses the low-frequency components of the exhaust gas. On the other hand, in the middle and high rotation regions where the exhaust pressure and the flow rate increase, exhaust is also exhausted from the chamber 5 and the tail tube 13, so that high-frequency components can be silenced while reducing exhaust loss, and the engine is fully rotated. Exhaust noise can be reliably reduced while suppressing a decrease in output in the region, and the configuration of the device can be simplified without requiring a motor and its control means, thereby suppressing an increase in manufacturing cost.

The valve 16 has a structure in which the valve 16 slides away from the through hole 17 of the baffle plate 8 by sliding along the pass tube 10, so that the rate of change of the opening area with respect to the amount of expansion and contraction of the return spring 29 is greater than that of the conventional reed valve 16 or the like.
The airflow noise generated from the valve 16 is sufficiently silenced, and exhaust loss (increase in exhaust pressure) in a high rotation range is reduced to suppress a decrease in engine output.

The disc-shaped valve 16 is used for the pass tube 1.
With the structure that fits to 0, it is possible to prevent the valve 16 from dropping from the muffler 1 due to deterioration with time.

When the valve 16 slides on the outer peripheral surface 19 of the pass tube 10 via the plurality of guide claws 22,
The friction of the valve 16 can be reduced, and noise can be prevented from occurring when the valve 16 slides.

The structure in which the buffer member 30 is interposed between the baffle plate 8 and the valve 16 can prevent noise from being generated when the valve 16 is seated on the baffle plate 8 side.

Return spring 29 is connected to pass tube 1
By forming the coil into a coil shape that is inserted into the muffler 1, the structure can be simplified, and the return spring 29 can be prevented from dropping from the muffler 1 due to aging.

When the valve 16 is opened, the coil-shaped return spring 29 is located behind the valve 16 with respect to the flow of exhaust gas, so that the return spring 29 is prevented from being exposed to a high-speed exhaust gas flow. Return spring 2
9 can be suppressed.

[0056]

As described above, the exhaust gas muffler for an engine according to the first aspect has a structure in which the valve slides on the pass tube against the return spring to open and close the second exhaust passage. Since the motor and the like are not required, the structure can be simplified, and the manufacturing cost can be reduced. Also,
The structure in which the valve slides away from the through hole of the baffle plate by sliding the pass tube has a larger change rate of the opening area with respect to the amount of expansion and contraction of the return spring than conventional reed valves, etc., and sufficiently suppresses the airflow noise generated from the valve And exhaust loss in the high speed range (increase in exhaust pressure)
And a decrease in engine output can be suppressed.

In the engine exhaust silencer according to the second aspect, the valve slides on the outer peripheral surface of the pass tube via the plurality of guide claws, thereby reducing the friction of the valve and sliding the valve. In this case, noise can be prevented from being generated.

In the engine exhaust silencer according to the third aspect, the structure in which the cushioning material is interposed between the baffle plate and the valve can prevent the generation of noise when the valve is seated on the baffle plate side. .

According to a fourth aspect of the present invention, the exhaust muffler of the engine is formed in a coil shape in which the return spring is inserted into the pass tube, thereby simplifying the structure and dropping the return spring from the muffler due to aging. Can be prevented. Further, the valve is prevented from being exposed to the high-speed exhaust gas flow, and deterioration of the return spring is suppressed.

According to a fifth aspect of the present invention, there is provided an exhaust muffler for an engine in a low engine speed range by a resonator formed of a chamber partitioned by a valve and a baffle plate and a pass tube with the valve closing a through hole. While effectively reducing frequency noise, exhaust is exhausted through the pass tube in the high engine speed range where the valve opens, reducing exhaust noise while suppressing exhaust loss in the middle and high speed ranges. .

[Brief description of the drawings]

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

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

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 muffler 2 chamber 3 chamber 4 chamber 6 baffle plate 8 baffle plate 12 tail tube 13 tail tube 14 insertion hole 16 valve 17 through hole 19 outer peripheral surface of pass tube 21 inner peripheral edge of valve 22 guide claw 29 return spring 30 cushioning material

Claims (5)

(57) [Claims] A muffler for reducing exhaust noise of the engine, a first exhaust passage and a second exhaust passage for discharging exhaust gas guided from the engine to the muffler, and an exhaust pressure of the engine generated inside the muffler. Valve means for responsively opening a second exhaust passage, wherein the valve means comprises: a through hole opened in a baffle plate defining two chambers; and a gap in the through hole. A pass tube that is inserted to define the second exhaust passage, a valve that is slidably fitted to the outer peripheral surface of the pass tube, and a return spring that presses the valve against the baffle plate to close the through hole. An exhaust muffler for an engine, comprising: 2. The valve according to claim 1, wherein an insertion hole is formed in the valve so as to fit with an outer peripheral surface of the pass tube with a gap, and a plurality of guide claws are formed in the valve so as to slide on the outer peripheral surface of the pass tube. An exhaust silencer for an engine according to claim 1. 3. An exhaust muffler for an engine according to claim 1, wherein a cushioning material is interposed between said baffle plate and said valve. 4. The apparatus according to claim 1, wherein said return spring is formed in a coil shape to be inserted into a pass tube.
The exhaust muffler for an engine according to any one of claims 1 to 3. 5. A chamber defined by a valve and a baffle plate in a state in which the valve closes a through hole, the resonance chamber communicating with a second exhaust passage via a pass tube. 5. The exhaust muffler for an engine according to any one of claims 1 to 4.