JPH0688515A - Muffler - Google Patents

Abstract

PURPOSE:To reduce or avoid hunting phenomenon and chattering phenomenon caused by means of a stroke when a noise eliminating valve 20 is closed. CONSTITUTION:A muffler consists of a pipe body 1 provided with an exhaust passage 14, a static pressure taking-in port 40, and an auxiliary chamber 16, a rocking valve 2 provided with a noise eliminating valve 20 and a damping valve 22, and a torsion coil spring for energizing the noise eliminating valve 20 in its closing direction. A static pressure taking-in port 40 is formed apart from a valve shaft 24 by L4 distance so as to avoid the stagnant pressure range of the noise eliminating valve 20. Valve opening force Falpha for opening the noise eliminating valve 20 is determined by the total pressure of fluid which flows in an exhaust passage 14 basically. Valve closing force Fbeta for closing the noise eliminating valve 20 is caused by the sum of energizing force Fbeta1 caused by static pressure taken from the static pressure taking-in port 40 into the auxiliary chamber 16 and acting on the damping valve 22, and energizing force Fbeta2 of a spring 3. The total pressure of fluid in the exhaust passage 14 is basically in the same phase as that of static pressure taken from the static pressure taken-in port 40 into the auxiliary chamber 16, and the valve opening force Falpha and the valve closing force Fbeta are fluctuated in the same phase basically.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a muffler for reducing exhaust noise of a fluid exhibiting pulsating pressure. The present invention can be applied to, for example, an exhaust system that exhausts exhaust gas from an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, in a muffler, for example, a muffler used for an exhaust system of an internal combustion engine, a swing valve provided in an exhaust passage through which exhaust gas flows and a swing valve are energized. The following is known as a spring having a spring. That is, as shown in FIG.
In addition, there is known a silencer in which a swing valve 102 is pivotally supported by a shaft 104 so as to swing, and a spring 106 biases the swing valve 102 in a valve closing direction, that is, an arrow A1 direction (JP-A-58).
No. 217714). In this case, the degree of opening of the rocking valve 102 increases as the pressure of the exhaust gas increases. In this case, in the light load operation range of the internal combustion engine, that is, when the pressure of the exhaust gas is low, the passage area of the exhaust passage 100 is throttled by the oscillating valve 102, and the effect of silencing exhaust noise is obtained.

Further, as shown in FIG. 8, a tank chamber 206 communicating with openings 202 and 204 facing the side of the exhaust passage 200 is provided, and the tank chamber 206 is provided with a shaft 208.
There is known a silencer in which the rocking valve 210 is pivotally supported by the rocking mechanism and the rocking valve 210 is biased by a spring 212 so as to open the opening 202 (Japanese Utility Model Laid-Open No. 3-114512). In this structure, a part of the exhaust gas flowing through the exhaust passage 200 is temporarily stored in the tank chamber 206 through the opening 202, and then,
Since the swing valve 210 swings in the direction of arrow A3 to open the opening 204, the exhaust gas in the tank chamber 206 is discharged from the opening 204. In this case, the exhaust gas is divided and discharged, so that a sound deadening effect is expected.

Further, as shown in FIG. 9, there is known a silencer in which a thin plate-shaped valve 302 having a bent portion 300 is arranged substantially parallel to an inner wall surface of an exhaust passage 304 (actually open 3-8992).
No. 2). The bent portion 300 is located on the outlet side of the exhaust passage 304. In this device, attention is paid to the fact that noise having a high-frequency component such as exhaust burr is caused by the pulsating flow that flows in the negative direction, that is, the arrow A5 direction, and the bending portion 300 of the valve 302 causes the pulsating flow in the negative direction. Is to prevent.

Further, as shown in FIG. 10, a through hole 40 communicating with the outside air is formed in a wall of a sub chamber 402 which is continuously provided in the exhaust passage 400.
3 is provided, the swing valve 404 is supported by a plurality of springs 406, the first valve 408 of the swing valve 404 is arranged in the exhaust passage 400, and the second valve 410 is arranged in the auxiliary chamber 402. (Japanese Patent Publication No. 2-501585). In this case, the first valve 408 and the second valve 410 of the swing valve 404 are included.
Oscillate in opposite directions. As a result, the exhaust passage 40
A flow having an opposite phase to the pulsating flow that flows through 0 is generated in the sub chamber 402, and the pulsating flow in the exhaust passage 400 and the flow having the opposite phase in the sub chamber 402 interfere with each other in the united space 410 to obtain a silencing effect.

[0006]

By the way, in the silencer as shown in FIG. 7 described above, a method of urging the rocking valve 102 by the spring 106 in the valve closing direction, that is, the arrow A1 direction is adopted. Specifically, the valve opening force Fα for opening the oscillating valve 102
Is determined by the total pressure of the fluid flowing through the exhaust passage 100, while the valve closing force Fβ for closing the rocking valve 102 is determined by the biasing force of the spring 106.

Therefore, when the pressure on the upstream side H of the oscillating valve 102 is released with the opening of the valve, the total pressure on the upstream side H of the oscillating valve 102 decreases, so that the valve opening force Fα suddenly decreases. Then
Therefore, the valve closing force Fβ becomes considerably larger than the valve opening force Fα. Therefore, the rocking valve 102 suddenly closes and the exhaust passage 1
The hunting phenomenon of hitting the stopper portion 100a of No. 00 is likely to occur. Further, since the exhaust gas discharged from the internal combustion engine exhibits a pulsating pressure, a chattering phenomenon in which impact sounds are continuous is likely to occur.

Particularly in a vehicle, there is a wide operating range where a chattering phenomenon occurs due to the influence of the pulsating pressure of exhaust gas. For example, pulsating pressure is generated in the exhaust passage 100 due to the valve system even during deceleration of the vehicle in which the flow of exhaust gas is basically not present. At this time, the swing valve 10 in a state close to the closed valve
Since pulsating pressure acts on 2, chattering is likely to occur. In order to avoid such chattering phenomenon, the spring 10
6 may be strengthened, but in this case, the spring 1
Since the biasing force of 06 is strong, there is a problem in that the degree of valve opening required for accelerating the vehicle cannot be obtained.

The present invention has been made in view of the above situation, and an object thereof is to make a static pressure in the same phase as the total pressure of a fluid acting as a valve opening force act as a valve closing force.
Hunting phenomenon caused by impact when the silencer valve closes,
An object of the present invention is to provide a silencer that is advantageous in reducing or avoiding the chattering phenomenon.

[0010]

DISCLOSURE OF THE INVENTION A muffler of the present invention comprises a main passage through which a fluid exhibiting a pulsating pressure flows from upstream to downstream, a valve support portion, and a main passage that is upstream of the valve support portion. A tubular body having a static pressure inlet opening and a sub-chamber communicating with the static pressure inlet, and a valve support part of the tubular body swingably supported and openably and closably arranged in the main passage. A muffler valve that is urged in the valve opening direction by receiving the total pressure of the fluid in the passage, and a muffler valve that is integrated with the muffler valve and is swingable in the auxiliary chamber and receives the static pressure from the static pressure intake port. Is composed of a swing valve having a damping valve for urging the silencer valve in the closing direction and a spring for urging the silencer valve in the closing direction. It is characterized in that the static pressure in the same phase as the pressure acts as a valve closing force on the damping valve via the static pressure inlet.

The main passage is for passage of fluid and may have a circular cross section or a rectangular cross section. The static pressure inlet is formed so as to avoid the stagnation pressure region that occurs in the silencer valve. The rocking valve has a muffling valve that opens and closes the main passage, and a damping valve that is arranged in the sub chamber. The oscillating valve preferably has an L-shaped cross section, as illustrated in the examples described later. The valve support portion supports the swing valve, and can be formed by using a shaft, a bearing, a cylindrical body, or the like. The spring urges the muffler valve in the valve closing direction, and a known spring, for example, a torsion coil spring, a tension coil spring, a leaf spring, or the like can be appropriately adopted.

[0012]

[Function] The silencer valve swings in the valve opening direction by the fluid flowing through the main passage. Therefore, the valve opening force Fα for opening the silencer valve is basically caused by the total pressure of the fluid flowing through the main passage. On the other hand, the valve closing force Fβ for closing the silencer valve is due to the sum of the biasing force Fβ _{1 of} the static pressure taken from the static pressure intake port into the sub chamber acting on the tamping valve and the biasing force Fβ _{2 of the} spring. To do.

When Fα is larger than Fβ, the muffler valve swings in the valve opening direction. At this time, the difference of (Fα-Fβ) acts as a force for driving the silencer valve in the valve opening direction. When Fβ is larger than Fα, the silencer valve closes. When Fα and Fβ are in equilibrium, the silencer valve stops at its swing angle. By the way, in the present invention, the total pressure of the fluid in the main passage for opening the silencer valve,
The static pressure introduced from the static pressure inlet into the sub chamber is basically in phase. Therefore, the valve opening force Fα and the valve closing force Fβ
Basically fluctuate in phase.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a vehicle silencer will be described below with reference to FIGS. 1 and 2 are cross-sectional views of the muffler cut horizontally. This silencer is part of the exhaust system of the vehicle. The pipe body 1 constituting the silencer includes a main pipe 10 and a sub member 11 fixed to the main pipe 10.
It consists of and. An exhaust passage 14 as a main passage is formed on the inner wall surface of the main pipe 10. In the exhaust passage 14, the exhaust gas having a pulsating pressure flows from upstream to downstream, that is, in the direction of arrow B1. A sub chamber 16 is formed on the inner wall surface of the sub member 11. Since the sub member 11 is provided on the lateral side wall of the main pipe 10, it is advantageous for suppressing the height of the pipe body 1 and the vehicle height.

The rocking valve 2 includes a muffler valve 20 arranged in the exhaust passage 14, a damping valve 22 connected to the muffler valve 20 and arranged in the sub chamber 16, the muffler valve 20 and the damping valve 2.
2 is constituted by a stopper 24a or a valve shaft 24 fixed by welding. As shown in FIG. 3, one end portion 24 of the valve shaft 24
A cylindrical body 26 is held in a in a non-rotating state. The valve shaft 24 is a support cylinder 1 as a valve support portion formed in the tubular body 1.
A and b are swingably supported by a bush 28 of a solid lubricant system. Note that 29 is a cap.

The spring 3 is a torsion coil spring that exerts a predetermined urging force. As shown in FIG. 3, one end 3a of the spring 3 is locked to the cylindrical body 26, and the other end 3b thereof is a pin-shaped projection 1e of the support cylinder 1a. Is locked to. As a result, when the internal combustion engine is not in operation, as shown in FIG. 1, the silencer valve 20 is biased in the valve closing direction, that is, in the direction of arrow C1 and is in contact with the stopper portion 1r. It is closed.

As shown in FIG. 1, a static pressure inlet 40 is formed on the side wall of the main pipe 10 on the upstream side of the valve shaft 24 of the rocking valve 2. The static pressure intake 40 communicates with the sub chamber 16 through a connecting pipe 42 having an L-shaped passage 41. Therefore, the static pressure introduced from the static pressure inlet 40 acts on the damping valve 22 in the sub chamber 16. The L-shaped passage 41 is the exhaust passage 14
A first passage 41a having a length L2 in a direction orthogonal to
The second passage 4 which is substantially parallel to the exhaust passage 14 and has a length L3
1b and. Although the sum of L2 and L3 can be set as appropriate, it is set to about 3 to 10 cm in this embodiment.

As shown in FIG. 1, the static pressure inlet 40 described above.
Is formed at a position separated from the valve shaft 24 by a distance L4. The reason for the distance L4 is as follows. That is, FIG. 4 schematically shows the device of this example, and the silencer valve 20
Muffler valve 2 because it functions as an obstacle to the flow
On the front side of 0, a stagnation pressure region S along the flow line of the flow occurs as shown by hatching in FIG. 4, so that the static pressure inlet 40 is formed so as to avoid the stagnation pressure region S, and the sub chamber 16 This is because only static pressure is applied to. Therefore, the dynamic pressure of the exhaust passage 14 does not act on the sub chamber 16.

Here, the fundamental wavelength λ of the pulsating pressure of the exhaust gas flowing through the exhaust passage 14 varies somewhat depending on the type of internal combustion engine, the rotation range of the internal combustion engine, etc., but is generally 15 m to 2 m.
It is a degree. Therefore, the length of the L-shaped passage 41 (L
2 + L3) is a distance much shorter than the fundamental wavelength λ of the pulsating pressure of the exhaust gas flowing through the exhaust passage 14. Therefore, in this embodiment, the total pressure of the fluid in the exhaust passage 14 that urges the silencer valve 20 in the valve opening direction and the static pressure in the sub chamber 16 are basically in the same phase.

In the present embodiment, the exhaust gas from the internal combustion engine flows through the exhaust passage 14 in the direction of arrow B1, and the muffler valve 20 is pressed by the exhaust gas. Then, as shown in FIG. 2, the silencer valve 20 swings in the valve opening direction, that is, the arrow C2 direction. FIG. 2 shows a state in which the valve opening angle of the muffler valve 20 is the angle θ. Here, the valve opening force Fα for opening the silencer valve 20 is due to the total pressure of the fluid flowing through the exhaust passage 14. In addition, the silencer valve 20
The valve closing force Fβ for closing is due to the sum of the urging force Fβ ₁ acting on the tamping valve 22 by the static pressure taken into the sub chamber 16 from the static pressure inlet 40 and the urging force Fβ ₂ by the spring 3. Then, the difference of (Fα−Fβ) acts as a force for driving the silencer valve 20 in the valve opening direction, and as the valve opening angle θ progresses, Fα and Fβ are balanced and the silencer valve 20 is in its swing position. Stop.

As described above, when the exhaust passage 14 is covered with the muffler valve 20 when the exhaust gas flows through the exhaust passage 14, the passage area of the exhaust passage 14 is narrowed and the fluctuation pressure due to the pulsating pressure of the exhaust gas is reduced. And a muffling effect is obtained. Therefore, the sound pressure discharged from the discharge end of the exhaust system decreases.
In particular, when the vehicle speed is low, exhaust noise having a low frequency component that causes a muffled noise in the passenger compartment is likely to occur. In this respect, however, the valve opening force Fα is small at low speed and the muffling valve 20 is opened. Since the angle θ is small, the muffler valve 20 effectively throttles the exhaust passage 20, whereby the exhaust sound having a low frequency component is effectively silenced. Since the exhaust pressure of the exhaust gas is originally low at low speeds, there is practically no reduction in the performance of the internal combustion engine due to the throttle. At high speed of the vehicle, the total pressure of the exhaust passage 14 increases and the valve opening angle θ of the silencer valve 20 increases,
Exhaust gas emission is also secured.

Exhaust gas discharged from the internal combustion engine has a pulsating pressure. When the pulsating pressure acts in this way, there is a possibility that the hunting phenomenon or the chattering phenomenon, which is a striking sound that suddenly hits the stopper portion 1r when the muffling valve 20 is closed as described above, may be induced. In this regard, in this embodiment, the total pressure of the exhaust passage 14 acting as the valve opening force Fα on the muffling valve 20 and the static pressure of the sub chamber 16 acting on the damping valve 22 as the valve closing force Fβ are basically in the same phase. Yes, when the valve opening force Fα decreases, the valve closing force Fβ also decreases. Therefore, it is possible to prevent the silencer valve 20 from suddenly hitting the stopper portion 1r when the silencer valve 20 is closed. Therefore,
This is advantageous for reducing and avoiding the hunting phenomenon and chattering phenomenon.

The position at which the oscillating valve 2 is installed is not particularly limited as long as it is an exhaust system, but it can be generally installed in front of the main muffler. (Application example) The above device is applied to an exhaust system of a predetermined internal combustion engine. The exhaust gas from this internal combustion engine has the pressure characteristics shown in FIGS. Here, FIG. 5 schematically shows the state of the pulsating pressure of the exhaust gas flowing through the exhaust passage 14. The measurement was performed by driving an internal combustion engine (4 cylinders, 4 cycles) at 6000 rpm and measuring in front of the main muffler. A characteristic line D1 indicated by a broken line in FIG. 5 indicates the pulsation situation of the total pressure, and a characteristic line D2
Indicates the pulsation situation of static pressure, P1 indicates the average value of total pressure,
P2 shows the average value of static pressure. The fundamental wavelength λ of the pulsating pressure of exhaust gas is approximately 15 m to 2 m as described above. Even if the rotational speed of the internal combustion engine fluctuates, the exhaust gas basically exhibits a pulsating pressure corresponding to this. Exhaust gas exhibiting such a pulsating pressure flows through the exhaust passage 14.

FIG. 6 shows the relationship between the rotational speed of the internal combustion engine and the pressure of exhaust gas. The characteristic line E1 shows the average total pressure, and the characteristic line E2 shows the average static pressure. As shown in FIG. 6, the differential pressure (total pressure-static pressure) increases as the rotational speed of the internal combustion engine increases.
Since this pressure difference acts as a force for actually opening the muffling valve 20 together with the biasing force of the spring 3, the valve opening angle θ of the muffling valve 20 increases as the rotational speed of the internal combustion engine increases. Therefore, exhaust gas discharge performance in the high-speed rotation region of the internal combustion engine is ensured, and the ability of the internal combustion engine due to the muffler valve 20 does not actually decrease.

(Other Examples) In addition, the present invention is not limited to the embodiments described above and shown in the drawings,
For example, the exhaust passage 14 may have a circular cross-section, and the spring may be a tension coil spring.

[0026]

According to the silencer of the present invention, since the static pressure in the same phase as the total pressure of the fluid acting as the valve opening force Fα acts as the valve closing force Fβ, the valve opening force Fα and the valve closing force Fβ. Basically fluctuate in phase. Therefore, when the valve opening force Fα acting on the muffler valve in the valve open state suddenly decreases and the muffler valve tries to close, the valve closing force Fβ also decreases. Therefore, the impact of the muffler valve that occurs when the valve is closed is reduced or avoided. Therefore, it is advantageous for reducing or avoiding the hunting phenomenon and chattering phenomenon of the silencer valve.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a silencer in the horizontal direction showing a state in which the silencer valve is closed.

FIG. 2 is a cross-sectional view of the silencer in the horizontal direction showing a state in which the silencer valve is partially opened.

3 is a cross-sectional view showing the vicinity of a pivotal support portion of the rocking valve taken along the line WW in FIG.

FIG. 4 is a schematic cross-sectional view of a silencer showing a region of stagnation pressure generated by a silencer valve.

FIG. 5 is a graph showing a situation of pulsating pressure of exhaust gas flowing through an exhaust passage.

FIG. 6 is a graph showing the relationship between the rotation speed of the internal combustion engine and the pressure of exhaust gas.

FIG. 7 is a schematic cross-sectional view of a silencer according to a conventional example.

FIG. 8 is a schematic cross-sectional view of a silencer according to another conventional example.

FIG. 9 is a schematic cross-sectional view of a silencer according to another conventional example.

FIG. 10 is a schematic cross-sectional view of a silencer according to another conventional example.

DESCRIPTION OF SYMBOLS In the figure, 1 is a tubular body, 10 is a main pipe, 11 is an auxiliary member, 14 is an exhaust passage (main passage), 16 is an auxiliary chamber, 2 is a swing valve, 20 is a silencer valve, and 22 is damping. Valve, 24 is a valve shaft, 3 is a spring, 4
Reference numeral 0 indicates a static pressure inlet, and 41 indicates an L-shaped passage.

Claims (1)

[Claims] 1. A main passage through which a fluid exhibiting a pulsating pressure flows from upstream to downstream, a valve support portion, and a static pressure inlet opening facing the main passage upstream of the valve support portion. , A sub-chamber having a sub-chamber communicating with the static pressure inlet, and a valve support portion of the pipe, which is swingably supported, and is openably and closably arranged in the main passage so that all fluid in the main passage is opened. A silencer valve which is urged in the valve opening direction by receiving pressure, and arranged integrally with the silencer valve and swingable in the sub chamber to receive the static pressure from the static pressure intake port to activate the silencer valve. A fluid in the main passage configured by a rocking valve having a damping valve for urging the silencer valve and a spring for urging the silencer valve in the closing direction, and urging the silencer valve in the opening direction. A silencer characterized in that a static pressure in the same phase as the total pressure of (3) acts on the damping valve as a valve closing force via the static pressure inlet.