JP3044963B2 - Silencer for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a muffler provided in an exhaust system of an internal combustion engine.

[0002]

2. Description of the Related Art A butterfly valve is provided in a pipe communicating between a plurality of chambers in a muffler, and the valve is closed to increase noise reduction when the exhaust flow rate is relatively small. The silencer of the internal combustion engine equipped with a butterfly valve, which was opened to prevent the back pressure of the internal combustion engine from rising,
For example, it is known from Japanese Utility Model Laid-Open No. 3-17130.

FIG. 5 shows a structure near a butterfly valve of a muffler for an internal combustion engine to which the present invention is to be improved. In the structure of FIG. 5, a butterfly valve that is operated by the dynamic pressure of exhaust gas is provided in the muffler, and the valve shaft 12 and the valve shaft guide 23 that supports the valve shaft extend outward from the muffler wall. It has been extended. A coil spring 14 is provided on the outer peripheral side of the valve shaft guide 23. One end of the coil spring 14 is connected to the valve shaft 12 and the other end is connected to the valve shaft guide 23, thereby rotating the valve shaft 12 in the valve closing direction. It is energizing. Therefore, the butterfly valve
Large pressure and coil spring force due to added exhaust gas flow
Opening and closing of butterfly valve by small relation
And no external drive source is required to open the valve.
On the other hand, coil spring force greatly affects valve opening and closing characteristics
It has a structure to do.

[0004]

However, in the structure shown in FIG. 5, the portion of the coil spring 14 located on the outer peripheral portion of the valve shaft guide, in particular, the portion 28 near the claw engaged with the valve shaft guide side is a valve. A portion 29 that is in contact with the shaft guide 23 and located on the outer peripheral portion of the valve shaft 12 contacts the valve shaft 12. Since high-temperature exhaust gas flows in the muffler wall, heat in a portion of the valve housing of the butterfly valve inside the muffler wall is transmitted to a valve shaft guide and a valve shaft outside the muffler wall by heat conduction. Among them, the valve shaft guide becomes considerably high temperature, the temperature of the coil spring in contact therewith rises, and the spring constant decreases, so that the valve opening / closing characteristics change, the valve opens from a rotation speed lower than the predetermined rotation speed, and the exhaust gas There was a problem that the muffled sound in the vehicle interior deteriorated.

An object of the present invention is to provide a silencer for an internal combustion engine that can reduce heat transfer from a valve shaft guide to a coil spring and maintain good silencing characteristics of the silencer.

[0006]

According to a first aspect of the present invention, there is provided a silencer for an internal combustion engine according to the present invention. (1) A valve shaft of a butterfly valve provided in the muffler and a valve shaft guide supporting the valve shaft are extended outward from the muffler wall, and one end of the valve shaft guide is provided on the outer periphery of the valve shaft guide. A coil spring is attached to the guide side, the other end of which is connected to the valve shaft side, for urging the valve shaft to rotate in the valve closing direction.
And the pressure due to the exhaust gas flow applied to the butterfly valve
Butterfly valve due to the magnitude relationship with the il spring force
A silencer device for an internal combustion engine for opening and closing the blanking, internal combustion that between the valve shaft guide and the coil spring, characterized in that a substantially cylindrical cover member having a space between the valve shaft guide Engine silencer. (2) The end of the cover member is bent inward.
The silencing device for an internal combustion engine according to (1). (3) A projection projecting inward from an end of the cover member.
The muffler for an internal combustion engine according to (1), wherein: (4) The rigidity of the cover member is higher than the valve shaft.
Netsu膨 Zhang amount of guide buckles when it becomes a predetermined amount
(1) The silencing device for an internal combustion engine according to (1),
Place.

[0007]

According to the first aspect of the present invention, the cover member is provided between the coil spring and the valve shaft guide, and a space exists between the cover member and the valve shaft guide. The heat conduction from the valve shaft guide to the cover member is cut off by the space, and the convective heat transfer from the valve shaft guide to the cover member through the space is small. Spring temperature rise is reduced. For this reason, the valve opening / closing characteristics of the coil spring hardly change, and the noise reduction characteristics of the noise reduction device are also maintained at the predetermined characteristics. (2) The noise reduction device for an internal combustion engine of the present invention according to the above (2).
Then, between the valve shut guide and the cover member,
An air layer is formed. (3) The internal combustion engine of the present invention
In the silencer, the cover member is connected to the valve shut guide.
The contact area is minimized, and the heat insulating effect is enhanced. the above
(4) In the noise reduction device for an internal combustion engine according to the present invention, the valve
Influence on coil spring due to thermal expansion of guide
Is controlled.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows the overall configuration of a silencer for an internal combustion engine according to an embodiment of the present invention. In FIG. 1, 1 is a silencer, 2 is an inlet pipe, 3 is a resonance pipe, 4 is an outlet pipe, 5 is a low-frequency resonance chamber, 6 and 7 are expansion chambers,
8 and 9 are inner pipes and 10 is a bypass pipe. Up to this point, the conventional apparatus is used.

A guide pipe 11 that bends the flow direction is attached to the tip of the bypass pipe 10, and a butterfly valve (hereinafter, also referred to as a valve) 2 is attached to the tip of the guide pipe 11.
A valve housing 13 provided with a valve housing 2 is mounted. As shown in FIG. 2, the valve shaft 12 of the butterfly valve 22 is eccentric from the center of the valve body,
When the dynamic pressure of the exhaust gas exceeds a predetermined value, the valve is automatically opened.

As shown in FIG. 2, the valve shaft 12 is rotatably supported by a valve shaft guide 23, and the valve shaft guide 23 is integrated with the valve housing 13. The valve shaft guide 23 and the valve shaft 12 extend outward from the front end plate 24 of the silencer 1. The distal end of the valve shaft 12 extends further outward than the distal end of the valve shaft guide 23.

The valve shaft 12 is urged in the closing direction on the outer periphery of the valve shaft guide 23 and the valve shaft 12.
A coil spring 14 is provided. Claws 25 formed by bending the ends of the springs are provided at both ends of the coil spring 14, and the claw 25 at one end is connected to the valve shaft guide side (the valve shaft guide 23 or a member fixed thereto). The end claw 25 is connected to the valve shaft side (the valve shaft 12 or a member fixed thereto). As shown in FIG.
A stopper 15 for positioning the valve is provided at the distal end of the valve shaft 12, and a cushioning material 19 and a stopper receiver 16 of the stopper are fixed to an end plate 24 by bolts 18.

The valve 22 is normally operated at a rotation speed at which the low-frequency resonance chamber 5 operates (for example, 100 Hz for a six-cylinder engine).
In this case, the frequency is tuned. In this case, the valve 22 is opened at a speed of 2000 rpm or more. That is, it is set to open outside the muffled sound area in the vehicle caused by the primary explosion of the exhaust sound. When the valve 22 is opened, the low-frequency resonance chamber changes to an expansion chamber, which can reduce the sound of high-order components such as the secondary and tertiary explosions and the airflow noise, greatly reduce the engine back pressure, and increase the engine output. I do.

As shown in FIG. 2 in which the vicinity of the valve housing 13 is enlarged, a substantially cylindrical cover member (hereinafter, also referred to as a cover pipe) 26 is interposed between the coil spring 14 and the valve shaft guide 23. Is equipped. The front and rear ends of the cover pipe 26 are bent inward in the same direction as shown in FIGS. 3 and 4, and a space (hereinafter referred to as an air layer) between the cover pipe 26 and the valve shaft guide 23. 27) is formed.

In the configuration in which the cover pipe 26 is bent inward, the cover pipe 26 and the valve shaft guide 23 are almost in line contact. This makes it difficult for heat from the valve shaft guide 23 to be transmitted to the coil spring 14. If heat is more severe, cover pipe 26
, A projection protruding from the inner side to the inner side may be made to come into point contact with the valve shaft guide 23. The cover pipe 26 is made of a thin plate made of stainless steel and made of the same material as the coil spring 14 to prevent abrasion at a contact portion between the coil spring 14 and the cover pipe 26 and to consider corrosion resistance (electrolytic corrosion resistance).

The valve shaft guide 23 has a radial thermal expansion due to the heat transfer from the valve housing 13.
By setting the rigidity of the cover pipe 26 to such an extent that the cover pipe 26 digs and absorbs the displacement before the coil spring is pushed out, the cover pipe 2
Numeral 6 absorbs thermal expansion of the valve shaft guide 23 so that an unreasonable load is not applied to the coil spring 14.

Next, the operation will be described. The valve housing 13 is constantly exposed to the exhaust gas flow regardless of whether the valve 22 is opened or closed, and thus has a high temperature during operation of the engine. The valve shaft guide 23 is a valve housing 23
The heat of the valve housing 23 is mainly transmitted to the valve shaft guide 23 by heat conduction, and the temperature of the valve shaft guide 23 also increases.

However, since the cover pipe 26 is inserted between the coil spring 14 and the valve shaft guide 23, and the air layer 27 exists between the cover pipe 26 and the valve shaft guide 23, the valve Heat transfer from the shaft guide 23 to the coil spring 14 is greatly suppressed. Since the valve shaft guide 23 and the cover pipe 26 are substantially in line contact or point contact, heat conduction through the contact portion is small (due to small area). The convective heat transfer from the valve shaft guide 23 to the cover pipe 26 is also small because the thickness of the air layer 27 is small and the air is difficult to convect due to the viscosity. Valve shaft guide 23
The radiant heat transfer from the cover pipe 26 to the cover pipe 26 is negligible because it is not in such a high temperature region that radiation is a problem. Therefore,
Due to the insertion of the cover pipe 26, the amount of heat transferred from the valve shaft guide 23 to the coil spring 14 is reduced.

Further, since the cover pipe 26 is mounted in a floating state, the abrasion generated when the coil spring 14 operates at the contact portion between the coil spring 14 and the valve guide can be reduced. Note that heat conduction from the valve shaft 12 to the coil spring 14 due to the contact between the valve shaft 12 and the coil spring 14 at the valve shaft tip does not pose a problem because heat transfer distance attenuation is large.

[0019]

According to the first aspect of the present invention, there is provided a silencer for an internal combustion engine.
For example , since a substantially cylindrical cover member (cover pipe) having a space (air layer) between the valve shaft guide and the coil shaft spring is provided between the valve shaft guide and the coil spring, the temperature of the valve becomes high during operation of the engine. Heat conduction from the shaft guide to the coil spring can be reduced, and the coil spring can be prevented from becoming hot. As a result, it is possible to prevent the opening / closing characteristics of the butterfly valve from changing, and to maintain the set silencing characteristics.
According to the silencing device for an internal combustion engine of the second aspect, the valve shut
An air layer can be reliably formed between the guide and the cover member.
You. According to the muffler for an internal combustion engine of claim 3, the cover portion
The contact area of the material with the valve shut guide is minimized, and heat insulation
The effect can be enhanced. The silencing of the internal combustion engine according to claim 4.
According to the device, coiling due to thermal expansion of the valve shut guide
Effect on the spring can be suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic overall sectional view of a silencing device for an internal combustion engine according to one embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a butterfly valve and its vicinity in the apparatus of FIG.

FIG. 3 is a front view of a cover member (cover pipe) in FIG. 2;

FIG. 4 is a side view of the cover member including a cross section along line 4-4 in FIG. 3;

FIG. 5 is an enlarged sectional view of a butterfly valve of a silencer to which the present invention is applied and the vicinity thereof.

[Explanation of symbols]

 Reference Signs List 1 muffler 10 bypass pipe 11 guide pipe 12 valve shaft 13 valve housing 14 coil spring 22 butterfly valve (valve) 23 valve shaft guide 26 cover member (cover pipe) 27 space (air layer)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References Japanese Utility Model 3-17130 (JP, U) Japanese Utility Model 3-102014 (JP, U) Japanese Utility Model 4-5916 (JP, U) Japanese Utility Model 3 25830 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F01N 1/08 F01N 7/14

Claims (4)

(57) [Claims] A valve shaft of a butterfly valve provided in a muffler and a valve shaft guide supporting the valve shaft extend outward from a muffler wall, and one end of the valve shaft guide is provided at an outer periphery of the valve shaft guide. the other end on the guide side is connected to the valve shaft side, is disposed a coil spring for urging rotation of the valve shaft in the valve closing direction, pressure by the exhaust gas stream acting on butterfly valve
Butterflies due to the magnitude relationship between the force and the coil spring force.
A silencer device for an internal combustion engine for opening and closing the Ibarubu, between the valve shaft guide and the coil spring,
A silencer for an internal combustion engine, comprising a substantially cylindrical cover member having a space between the cover member and a valve shaft guide. 2. An end of the cover member is bent inward.
The silencing device for an internal combustion engine according to claim 1, wherein 3. An end of the cover member protrudes inward.
2. The exhaust of an internal combustion engine according to claim 1, further comprising:
Sound equipment. 4. The valve system according to claim 1, wherein the rigidity of said cover member is
Buckling occurs when the amount of thermal expansion of the shaft guide reaches a predetermined amount
The power consumption of the internal combustion engine according to claim 1, which is set to
Sound equipment.