JP2003120251A - Exhaust muffler for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To open and close a valve element at an exhaust pipe opening of an exhaust muffler used for a vehicle so that both of quietness at low engine speed and reduction of exhaust loss at high engine speed can be achieved. SOLUTION: The valve element 5 is supported on the opening of the exhaust pipe 1 of the exhaust muffler used for the vehicle rotatably around a predetermined rotating axis c1 to approaching and separating directions with respect to the opening. The valve element 5 is rotated and energized to the direction approaching to the opening of the exhaust pipe 1 so as to close the opening. An enlarged diameter part 3 having a diameter larger than an inside diameter of the exhaust pipe 1 is provided on the opening of the exhaust pipe 1, and a sheet surface 6 in correspondence with the shape of the enlarged diameter part 3 is provided on the valve element 5. Thus, the rotating axis c1 forms a predetermined angle α with respect to a virtual plane PL crossing an axis c2 of the exhaust pipe 1 at right angles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle exhaust silencer for reducing noise emitted from an exhaust system of an on-vehicle engine.

[0002]

2. Description of the Related Art Conventionally, as an exhaust muffler for a vehicle, as described in, for example, International Publication No. WO95 / 13460, an opening of an exhaust pipe of the exhaust muffler is opened and closed with respect to the opening. A valve body that is rotatable in an approaching direction and a direction away from the valve body is provided by being supported by a rotary shaft, and the valve body is rotationally biased in a direction approaching the opening of the exhaust pipe to close the opening. Things are known.

In this exhaust silencer, a plurality of exhaust passages provided in the exhaust silencer are opened by opening and closing the opening of the exhaust pipe by rotating the valve body according to the exhaust pressure of the engine. The purpose of the switching is to achieve both reduction of exhaust noise at low engine speed with a low exhaust flow rate and reduction of exhaust noise and exhaust loss at high engine speed with a high exhaust flow rate.

[0004]

However, in the conventional exhaust silencer, the rotating shaft supporting the valve element is installed downstream of the opening of the exhaust pipe in the exhaust flow direction. When the engine speed is relatively low and the flow rate is relatively low, the valve body is about to open, and the gap formed between the valve body and the opening is narrowed. Therefore, in such a conventional exhaust silencer, even if the exhaust flow rate increases due to an increase in the engine speed, the valve body does not open easily, or even if it opens, the opening degree is not sufficient, which causes a problem of high engine speed. However, there is a problem in that exhaust loss increases and exhaust flow noise increases due to high-speed exhaust.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an exhaust muffler for a vehicle which advantageously solves the above problems, and an invention according to claim 1 is provided. The exhaust muffler for a vehicle described above supports a valve element in an opening of an exhaust pipe of an exhaust muffler used in a vehicle so as to be rotatable about a predetermined rotation axis in a direction approaching the opening and a direction away from the opening. An exhaust muffler for a vehicle, wherein the valve body is rotatably biased in a direction approaching the opening of the exhaust pipe to close the opening. And a seat surface corresponding to the shape of the expanded portion is provided on the valve body, and the rotation axis is at a predetermined angle with respect to an imaginary plane orthogonal to the axis of the exhaust pipe. It is characterized in that it is arranged so that .

In the present invention, when the engine speed increases and the exhaust gas flow rate increases, the flow velocity of the engine causes the valve element supported by the opening of the exhaust pipe to open and rotate against the rotational biasing force. In this case, since the rotation axis of the valve element is arranged so as to be inclined at a predetermined angle with respect to the virtual plane orthogonal to the axis of the exhaust pipe, the valve element is orthogonal to the axis of the exhaust pipe when the valve element is opened and rotated. Displace in the direction. Therefore, when the present invention and the prior art are compared at the same rotation angle of the valve body, the present invention partially widens the gap between the enlarged diameter portion and the seat surface of the valve body. Therefore, when the flow rate of exhaust gas increases due to an increase in engine speed, the flow velocity of exhaust gas decreases immediately in the wide gap between the expanded diameter portion and the seat surface of the valve body as soon as the valve body starts to open and rotate. Since the fluid force (negative pressure) that applies the valve closing force to the valve body is eliminated and the valve body is easily opened, the valve body can be opened at a stretch.

Therefore, according to the exhaust muffler for a vehicle of the present invention, the valve body is closed by the strong valve closing force during the low engine speed when the exhaust flow rate is small, but the engine speed increases (the exhaust flow rate increases). As a result, the valve body can be opened at a stretch from a slightly opened state to secure a sufficient valve body opening degree, and the valve body can be rotated in the valve closing direction to achieve quietness at low engine speed. Even with a large biasing force, it is possible to improve exhaust loss and exhaust flow noise at high engine speeds, and improve quietness at low engine speed and exhaust loss and exhaust flow noise at high engine speeds. Can be compatible with both.

The exhaust silencer for a vehicle according to a second aspect of the invention is characterized in that the rotation axis of the valve element is arranged upstream of the position of the valve element in the closed state in the exhaust flow direction. It is a thing.

In the exhaust silencer for a vehicle according to the present invention, the pivot axis of the valve element is arranged upstream of the position of the valve element in the closed state in the exhaust flow direction. In addition to the effect, the valve body is rotated while being displaced so that the seat surface is displaced in a direction approaching the axis of the exhaust pipe of the valve body.

Therefore, according to the exhaust muffler for a vehicle of the present invention, the rate of expansion change of the gap between the enlarged diameter portion and the seat surface of the valve body is increased when the valve body is opened and rotated, and the valve body is Since it becomes easier to open, exhaust loss and exhaust flow noise at high engine speed can be reduced.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described in detail with reference to the drawings by way of examples. Figure 1
1 is a cross-sectional view showing an essential part of a vehicle exhaust silencer according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line aa of the essential part of the vehicle exhaust silencer shown in FIG. FIG. 5 is an explanatory view showing the action and effect of the vehicle exhaust muffler of this embodiment in the operating state of the valve element supported near the opening of the exhaust pipe.

In the vehicle exhaust muffler of this embodiment shown in FIG. 1, a valve seat 2 is provided at an opening of an exhaust pipe 1 in a housing (not shown) of the exhaust muffler, and the exhaust pipe 1 is attached to the valve seat 2.
The taper-shaped enlarged diameter portion 3 larger than the inner diameter is set. The valve seat 2 is further provided with a support portion s1 provided at the tip thereof for the rotation shaft 4
Is rotatably supported by the rotary shaft 4, and the valve seat 2 is opened and closed at the expanded diameter portion 3 by a support portion s2 provided on the valve body 5
It is rotatably supported and installed opposite. As a result, the valve body 5
Is supported by the valve seat 2 so as to be rotatable around a predetermined rotation axis line c1 in a direction approaching the diametrically expanded portion 3 and a direction away from the diametrical expansion portion 3.

The valve body 5 here has a tapered seat surface 6 formed corresponding to the shape of the expanded diameter portion 3, and the seat surface 6 is in contact with the expanded diameter portion 3 and the expanded diameter portion 3 thereof. Can be closed. Further, the rotating shaft 4 in this case is located closer to the exhaust flow A than the side end portion of the exhaust pipe 1 (that is, the position of the valve body 5 in the closed state).
It is located on the downstream side in the direction and outside the exhaust pipe 1, and is arranged so as to be inclined at a predetermined angle α with respect to the virtual plane PL orthogonal to the central axis c2 of the exhaust pipe 1. As a result, the rotary shaft 4 is inclined with respect to the virtual plane PL that includes the opening edge of the exhaust pipe 1 and is orthogonal to the central axis c2 of the exhaust pipe 1. In addition, PL 'in FIG. 1 is a virtual plane
The plane parallel to PL is shown.

Then, the valve body 5 is urged to rotate by a well-known return spring (not shown) in the direction of approaching the enlarged diameter portion 3 of the valve seat 2, so that the enlarged diameter portion 3 is normally moved to FIGS. 1 and 2. It shall be closed by the valve body 5 as shown in FIG.

The valve body 5 by the above-mentioned return spring force
In the predetermined low engine rotation range where the exhaust gas flow rate is low, the valve body 5 has a force that prevents the valve body 5 from being opened and rotated by the dynamic pressure from the exhaust flow A. It is assumed that the valve body 5 is opened and rotated against the return spring force by the dynamic pressure from the exhaust flow A in other relatively high engine rotation regions where the flow rate increases. As a result, the flow (pressure) of the exhaust gas shown in FIGS. 1 and 2 is applied to the valve body 5.
The valve closing force by the return spring acts so as to resist. The return spring force of the valve body 5 is determined to be a spring force that ensures that the valve body 5 maintains the closed position in the low engine rotation range where the valve body 5 needs to be closed for the quietness.

Next, the operation of the valve body 5 in the vehicle exhaust muffler of this embodiment will be described with reference to FIGS.
Under low engine speed with a low exhaust gas flow rate, the dynamic pressure of the exhaust flow cannot open the valve body 5 against the valve closing force of the return spring. Therefore, the valve body 5 can maintain the valve closed position (closed state) of FIG. 3 by the return spring, and the required quietness in a low engine rotation range can be secured as desired. In the coordinate axes shown in FIGS. 3 to 5, the Z axis is taken in the axial direction of the exhaust pipe 1 and the X axis is taken in the direction perpendicular to the axial line of the exhaust pipe 1.

When the exhaust gas flow rate increases as the engine speed increases, the dynamic pressure of the exhaust flow A causes the valve body 5 to resist the valve closing force of the return spring (not shown), as shown in FIG. Start opening. At that time, as described above, since the rotating shaft 4 is arranged obliquely (downward to the left with respect to the X axis in FIG. 4) with respect to the virtual plane PL including the opening end edge of the exhaust pipe 1, the valve The body 5 opens in the Z-axis direction and is displaced in the X-axis direction (leftward in FIG. 4).

Therefore, when the valve body 5 starts to open,
As shown in FIG. 4, with the opening rotation of the valve body 5, the gap between the enlarged diameter portion 3 and the seat surface 6 becomes narrower on the left side in FIG. 4 while on the right side in FIG. 8 becomes wider. For this reason,
Since the flow rate of the exhaust gas flowing through the gap 7 is small, the fluid force (negative pressure) generated in the gap 7 is also small. On the other hand, since the flow rate of the exhaust gas flowing through the gap 8 is large and the flow velocity V is also large, the fluid force (negative pressure) B generated in the gap 8 is large and acts in the direction of closing the valve body 5.

When the flow rate of exhaust gas further increases, the valve body 5
Is in the state shown in FIG. As shown here, when the flow rate of the exhaust gas increases and the amount of movement of the valve body 5 in the Z direction increases, when compared with the valve body in the conventional vehicle silencer at the same rotation angle, the gap 8 Is larger, the gap between the expanded diameter portion 3 and the seat surface 6 of the valve body 5 is partially widened. Thus, when the exhaust gas flow rate increases due to the increase in the engine speed, as soon as the valve body 5 starts to open and rotate, a wide gap (a gap 8) between the expanded diameter portion 3 and the seat surface 6 of the valve body 5 ), The flow of exhaust gas is indicated by arrow C in FIG.
Changes from the flow along the seat surface 6 to the flow away from the seat surface 6 as indicated by an arrow C in FIG.
Exhaust gas stagnation D occurs around the seat surface 6. In this way, in the gap 8, the flow velocity of the exhaust gas flowing around the seat surface 6 decreases, and the fluid force (negative pressure) B that gives the valve closing force to the valve body 5 sharply decreases. As a result of the valve closing force on the body 5 rapidly disappearing, the valve body 5 becomes easier to open, so that the valve body 5 is opened greatly at once by the dynamic pressure from the exhaust flow.

That is, when the valve element 5 of this embodiment and the valve element of the prior art are in the same predetermined turning angle, the valve element of the conventional valve element is fully opened with a small opening. However, according to the valve body 5 of the vehicle exhaust muffler of this embodiment, the gap between the expanded diameter portion 3 and the seat surface 6 can be partially increased due to the opening rotation. At that portion, the fluid (negative pressure) that gives the valve closing force to the valve element disappears, the valve element 5 is easily opened, and the valve element 5 can be fully opened at once.

As described above, in this embodiment, the valve body 5 is closed with a strong valve closing force during low engine speed with a low exhaust gas flow rate, but the engine speed increases (exhaust gas flow rate increases).
As a result, the valve body 5 can be opened at a stretch from a state in which the valve body 5 is slightly opened, and a sufficient valve body opening degree can be secured, so that the valve body 5 can be quieted at low engine speed. Even if the valve closing direction turning urging force is set to a large value, it is possible to avoid the problems that exhaust loss and exhaust flow noise increase due to high-speed exhaust at high engine speed. It is possible to achieve both improvement of exhaust loss and exhaust flow noise at the time of engine rotation and quietness at low engine speed.

FIG. 6 is a front view showing a partial cross section of an application example of the vehicle exhaust muffler of this embodiment applied to a dual tail type muffler for an automobile.
Here, the inside of the main muffler 20, which is the casing of the exhaust silencer, is partitioned by the two end plates 21 and 22, and the first chamber 23 and the second chamber 24 are separated.
And the third chamber 25 is defined. The main muffler 20 includes an inlet tube 26, a first tail tube 27,
A second tail tube 28 and a pass tube 29 are arranged. The main muffler 20 is shown so that the left side faces the inside of the vehicle body and the right side faces the atmosphere side, and the arrow indicated by a virtual line in FIG. 6 indicates the flow of the exhaust flow.

The inlet tube 26 here has a left side portion 26b and a right side portion 26c formed through a perforated pipe 26a integrally provided at an axially intermediate portion thereof, and the perforated pipe 26a is formed in the second chamber 24. The wall 20 that faces the inside of the vehicle so that it is located inside
a, the end plate 21 and the end plate 22 are inserted, whereby the left side portion 26b of the inlet tube 26 communicates with the second chamber 24 through the perforated pipe 26a.

The first tail tube 27 is an end plate.
The second chamber 24 is opened to the atmosphere via the first tail tube 27 by being inserted into the wall portion 20b of the main muffler 20 facing the atmosphere side. Also, the second tail tube 28 is an end plate.
The first chamber 23 is opened to the atmosphere through the second tail tube 28 by being inserted into the end plate 22, the end plate 22, and the wall portion 20b of the main muffler 20.

Further, the pass tube 29 has a valve seat 2, a diameter-increasing portion 3 and a rotating portion at the end on the side of the first chamber 23, as shown in FIGS. A valve 30 having a valve body 5 having a seat surface 6 supported by a valve seat 2 via a moving shaft 4 is fixed by welding or the like. The valve body 5 of the valve 30 is closed by a return spring (not shown) until the pressure inside the pass tube 29 reaches a certain value. Here, the valve closing force of the return spring is increased in order to sufficiently reduce low-frequency exhaust noise.

In the dual tail type muffler for an automobile having such a structure, as described above, the valve body 5 of the valve 30 is used.
Since the valve closing force is increased, the valve body 5 of the valve 30 does not open and the exhaust gas leaks when the engine speed is low at 2000 to 3000 rpm because the exhaust gas flow rate is small. Etc. does not occur. Moreover, due to the muffling element formed from the path from the inlet tube 26 to the first tail tube 27 via the second chamber 24, and the resonance element formed from the path between the inlet tube 26 and the third chamber 25. , The low frequency exhaust noise is sufficiently suppressed.

Then, for example, the engine speed is 4000 rp
When the engine is rotated at about m, the valve body 5 of the valve 30 starts to open and the flow of exhaust gas from the second tail tube 28 to the atmosphere is added, so that the air flow noise is reduced. Furthermore, for example, if the engine speed is 6000
When the valve body 5 of the valve 30 reaches a certain degree of opening at a high engine speed of rpm or more, the fluid force (negative pressure) B acting on the valve body 5 as shown in FIG. A portion of the gap between the seat surface 6 of the valve body 5 and the expanded diameter portion 3 sharply decreases to open the valve body 5 all at once, so that exhaust gas flows more from the second tail tube 28 to the atmosphere. As a result, exhaust loss can be significantly reduced.

FIG. 7 is a front view showing a partial cross-section of an example of application of the vehicle exhaust muffler of this embodiment to an automobile single-tail type muffler. Here, similar to the structure of the dual-tail type muffler for automobiles shown in FIG. 6, the inside of the main muffler 20 as the casing of the exhaust silencer is partitioned by the two end plates 21 and 22, and the first chamber
23, a second chamber 24 and a third chamber 25 are defined. And
The main muffler 20 here has an inlet tube 26,
A pass tube 29 and a tail tube 31 are arranged. Similar to FIG. 6, the left side of the main muffler 20 is directed toward the inside of the vehicle body and the right side of the main muffler 20 is directed toward the atmosphere side. Further, the arrow indicated by a virtual line in FIG. It shows the flow.

The inlet tube 26 and the pass tube 29 here have the same structure as the dual tail type muffler shown in FIG. Also here the tail tube
Reference numeral 31 denotes a perforated tube 31a integrally provided in an axially intermediate portion thereof.
A left side portion 31b and a right side portion 31c are formed through
The perforated tube 31a is inserted into the end plate 21, the end plate 22 and the wall portion 20b of the main muffler 20 so that the perforated tube 31a is located in the second chamber 24, whereby the left side portion 31b of the tail tube 31 is inserted into the perforated tube 31a. Communicates with the second chamber 24 and the first chamber 23 has a tail tube.
Open to the atmosphere via 31.

It should be noted that the pass tube 29 here is also provided at the end portion on the side of the first chamber 23, as shown in FIG.
As shown in FIG. 5, the valve 30 including the valve seat 2, the expanded diameter portion 3, and the valve body 5 having the seat surface 6 supported by the valve seat 2 via the rotating shaft 4 is fixed by welding or the like. The valve body 5 of the valve 30 is closed by a return spring (not shown) until the internal pressure of the pass tube 29 reaches a certain value. Here, as in the application example of the dual tail type muffler for automobiles, the valve closing force of the return spring is increased in order to sufficiently reduce low frequency exhaust noise.

In the single-tail type muffler for an automobile having such a structure, the valve body 5 of the valve 30 is as described above.
Since the valve closing force is increased, the exhaust gas flow rate is low at the time of low engine speed, so the valve body 5 of the valve 30 does not open, and the exhaust gas does not leak. Moreover,
A low-frequency exhaust gas is generated by the muffling element formed from the path from the inlet tube 26 to the tail tube 31 via the second chamber 24 and the resonance element formed from the path between the inlet tube 26 and the third chamber 25. The noise is completely silenced.

When the valve body 5 of the valve 30 reaches a certain degree of opening at high engine speed, the fluid force (negative pressure) B acting on the valve body 5 as shown in FIG. Suddenly decreases in a part of the valve body 5, the valve body 5 opens at a stretch, and exhaust gas flows more from the third chamber 25 to the atmosphere via the tail tube 31 via the pass tube 29. As a result, exhaust loss can be significantly reduced, as in the application example of the dual tail type muffler described above.

FIG. 8 is a cross-sectional view showing a main part of a second embodiment of the vehicle exhaust silencer of the invention, and FIG. 9 is a bb line of the main part of the vehicle exhaust silencer shown in FIG. Is a sectional view along
10 to 13 are explanatory views showing the action and effect of the vehicle exhaust silencer of this embodiment in the operating state of the valve element supported near the opening of the exhaust pipe, and FIG. 14 is shown in FIG. It is explanatory drawing for comparing the effect | action and effect of this Example, and the effect | action and effect of the said 1st Example. In FIGS. 8 to 14, the same components as those of the first embodiment are designated by the same reference numerals.

In the above first embodiment, as shown in FIGS. 1 to 5, the rotary shaft 4 is exhausted more than the side end portion of the exhaust pipe 1 (that is, the position of the valve body 5 in the closed state). Although it was provided on the downstream side in the flow A direction, in the second embodiment, as shown in FIGS. 8 and 9, the rotating shaft 4 has the side end portion of the exhaust pipe 1 (that is, in the closed state). (The position of the valve body 5 of FIG. 2) and the upstream side of the exhaust flow A in the outside of the exhaust pipe 1, and the rotation axis c1
Is arranged so as to be inclined at a predetermined angle α with respect to a virtual plane PL orthogonal to the central axis c2 of the exhaust pipe 1. As a result, the rotary shaft 4 is inclined with respect to the virtual plane PL that includes the opening edge of the exhaust pipe 1 and is orthogonal to the central axis c2 of the exhaust pipe 1. It should be noted that PL 'in FIG. 8 indicates a plane parallel to the virtual plane PL, and in this embodiment, the support portion s1 at the tip of the valve seat 2 and the support portion s2 of the valve seat 5 are configured to face downward. The rotary shaft 4 is rotatably supported by the rotary shaft 4, but the other structure is the same as that of the first embodiment.

Next, the operation of the valve element 5 in the vehicle exhaust muffler of this embodiment will be described with reference to FIGS.
Under a low engine speed with a low exhaust gas flow rate, the dynamic pressure of the exhaust flow A cannot open the valve body 5 against the valve closing force of the return spring, as in the first embodiment. Therefore, the valve body 5 can maintain the valve closed position (closed state) of FIG. 8 by the return spring (not shown), and can secure the required quietness in a low engine rotation range as desired. In the coordinate axes shown in FIGS. 8 and 10, the Z axis is taken in the axial direction of the exhaust pipe 1 and the X axis is taken in a direction perpendicular to the axial line of the exhaust pipe 1.

As the engine speed increases, the exhaust gas flow rate increases, and as shown in FIG. 12, the dynamic pressure of the exhaust flow A causes the valve body 5 to resist the valve closing force of the return spring (not shown). And start opening. At that time, as shown in FIG. 8, since the rotating shaft 4 is arranged obliquely with respect to the imaginary plane PL including the opening edge of the exhaust pipe 1 (obliquely leftward and downward with respect to the X axis in FIG. 8). , The valve body 5 is opened in the Z-axis direction and displaced in the X-axis direction (left direction in FIG. 8).
As shown in 13, the gap between the expanded diameter portion 3 and the seat surface 6 is partially widened by the gap 9. Therefore, similarly to the operation and effect of the first embodiment, the exhaust stagnation D occurs around the seat surface 6 on the side of the gap 9 and the fluid force (negative pressure) B acting on the seat surface 6 is suddenly increased. As a result, the valve closing force on the valve element 5 due to this negative pressure is rapidly lost, and as a result, the valve element 5 is opened greatly at a stretch due to the dynamic pressure from the exhaust flow.

That is, in the vehicle exhaust muffler of this embodiment, as shown in FIG. 12, when the valve body 5 starts to open, like the vehicle exhaust muffler of the first embodiment. Gap 9
Is narrow and the flow velocity V of the exhaust gas is high, a fluid force (negative pressure) B acts on the valve body 5 to exert a force in a direction to close the valve body 5. Then, when the exhaust gas flow rate increases with the high engine speed and the valve body 5 reaches a certain opening,
As shown in FIG. 12, the gap between the expanded diameter portion 3 and the seat surface 6 is wider in the gap 9, so that the flow of exhaust gas in the gap 9 is the same as that shown by C in FIG. The flow along the surface 6 changes to flow away from the seat surface 6. As a result, stagnation D of the exhaust gas is generated around the seat surface 6 on the side of the gap 9 and the flow velocity of the exhaust gas flowing around the seat surface 6 is slowed down, so that the fluid force (negative pressure) acting on the seat surface 6 is generated. B suddenly becomes smaller, and the valve element 5 due to this negative pressure
As a result that the valve closing force to the valve is rapidly lost, the valve body 5 is suddenly greatly opened by the dynamic pressure from the exhaust flow.

By the way, in the first embodiment, as shown in FIG. 14, since the rotary shaft 4 is provided on the exhaust gas downstream side of the side end portion of the exhaust pipe 1, the seat surface 6 rotates the valve body 5. Due to the movement, the lower edge of the seat surface 6, as shown by the locus γ in FIG.
A trajectory is drawn so as to be displaced in a direction away from the central axis c2 of the exhaust pipe 1. On the other hand, in the second embodiment, since the rotating shaft 4 is provided on the exhaust gas upstream side with respect to the side end portion of the exhaust pipe 1, the seat surface 6 of the seat surface 6 moves as the valve body 5 rotates. The lower edge is the central axis of the exhaust pipe 1, as shown by the locus β in FIG.
Draw a trajectory that displaces toward c2.

From this, when the valve body 5 of this embodiment shown in FIG. 11 and the valve body 5 of the first embodiment shown in FIG. 14 are compared at the same rotation angle, the seat surface 6 of this embodiment is Since the lower edge is displaced in the direction approaching the central axis c2 of the exhaust pipe 1, the gap 9 can be made larger than the gap 8 in the first embodiment as shown by the arrow E in FIGS. 11 and 14. Therefore, the action of the fluid force (negative pressure) that tends to close the valve body 5 can be reduced, and the valve body 5 can be opened more easily.

Therefore, according to the vehicle exhaust muffler of this embodiment, the rotary shaft 4 of the valve body 5 is arranged upstream of the position of the valve body 5 in the closed state in the exhaust flow direction. In addition to the actions and effects of the example vehicle exhaust silencer,
Since the valve body 5 is rotated while being displaced, the seat surface 6 is displaced while being displaced in a direction approaching the central axis c2 of the exhaust pipe 1 approaching the rotation axis 4 of the valve body 5. The rate of expansion change of the gap 8 between the enlarged diameter portion 3 and the seat surface 6 of the valve body 5 at the time of opening and rotating the body 5 becomes large, and the valve body 5 becomes easier to open. It is possible to reduce loss and exhaust flow noise. Moreover, there is an effect that the fluid force (negative pressure) acting on the valve body 5 at the time of opening and rotating the valve body 5 can be further reduced as compared with the vehicle exhaust silencer of this embodiment, and the opening degree can be reduced. As a result, the valve body 5 has a characteristic of opening at once.

The vehicle exhaust muffler of this embodiment can also be applied to the dual-tail type muffler and the single-tail type muffler shown as the application examples of the first embodiment.

Although the exhaust muffler for a vehicle according to the present invention has been described above based on the embodiment, the present invention is not limited to the above-mentioned example. For example, in the above embodiment, the expanded diameter portion 3 is used.
Is formed of a tapered surface, and the seat surface 6 is formed in a tapered shape corresponding to the expanded diameter portion 3,
The shape of the seat surface 6 is not limited to this. For example, the expanded diameter portion 3 may be configured by a trumpet-shaped convex curved surface, and the seat surface 6 may be configured by a concave curved surface shape corresponding to the expanded diameter portion 3. .

Further, in the first and second embodiments, as shown in FIGS. 1 and 8, the valve element 5 is inserted into the supporting portions s1 and s2 located in the left-right direction with one rotary shaft interposed. Since the valve seat 2 is supported by the valve seat 2, the axis of the rotary shaft 4 is the rotary axis c1. However, it is not limited to such a configuration, and, for example, FIG. 1 or FIG.
The left and right support parts s1 and s2 may be supported by separate members,
In addition, the support portion s2 may be pivotally supported by the support portion s1 by, for example, fitting recesses and projections provided on the support portions s1 and s2 without using the shaft member.

In the first and second embodiments described above, the exhaust pipe 1 is designed such that the plane including the opening is perpendicular to the axis of the exhaust pipe 1. The muffler is formed by slash-cutting the opening of the exhaust pipe 1, that is, the plane including the opening is the exhaust pipe 1.
The present invention can also be applied to those tilted with respect to the axis line of No. 1, and in that case, the tilt line and the rotation axis line may not be parallel to each other.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a main part of a first embodiment of a vehicle exhaust silencer of the invention.

FIG. 2 is a- of a main part of the vehicle exhaust silencer shown in FIG.
It is sectional drawing which follows the a line.

FIG. 3 is an explanatory view showing the action and effect of the vehicle exhaust muffler of the first embodiment in the operating state of the valve element supported near the opening of the exhaust pipe.

FIG. 4 is an explanatory view showing the action and effect of the vehicle exhaust muffler of the first embodiment in the operating state of the valve element supported near the opening of the exhaust pipe.

FIG. 5 is an explanatory view showing the action and effect of the vehicle exhaust muffler of the first embodiment in the operating state of the valve element supported near the opening of the exhaust pipe.

FIG. 6 is a front view showing a partial cross section of an application example in which the vehicle exhaust muffler of the first embodiment is applied to a vehicle dual-tail type muffler.

FIG. 7 is a front view showing a partial cross section of an application example in which the vehicle exhaust muffler of this embodiment is applied to a vehicle single-tail type muffler.

FIG. 8 is a sectional view showing an essential part of a second embodiment of the vehicle exhaust silencer of the invention.

9 is a main part of the vehicle exhaust muffler shown in FIG.
It is sectional drawing which follows the b line.

FIG. 10 is an explanatory view showing the action and effect of the vehicle exhaust silencer of the second embodiment in the operating state of the valve element supported near the opening of the exhaust pipe.

FIG. 11 is an explanatory view showing the action and effect of the vehicle exhaust silencer of the second embodiment in the operating state of the valve body supported near the opening of the exhaust pipe.

FIG. 12 is an explanatory view showing the action and effect of the vehicle exhaust silencer of the second embodiment in the operating state of the valve element supported near the opening of the exhaust pipe.

FIG. 13 is an explanatory view showing the action and effect of the vehicle exhaust silencer of the second embodiment in the operating state of the valve element supported near the opening of the exhaust pipe.

FIG. 14 is an explanatory diagram for comparing the operation and effect of the second embodiment and the operation and effect of the first embodiment shown in FIG.

[Explanation of symbols]

1 exhaust pipe 2 valve seat 3 Expanded part 4 rotation axis 5 valve body 6 seat surface 7, 8, 9 gap 20 Main muffler 20a, 20b wall 21, 22 end plates 23 Room 1 24 second room 25 Room 3 26 Inlet tube 26a, 31a Perforated tube 26b, 31b Left side 26c, 31c right side 27 1st tail tube 28 Second tail tube 29 pass tube 30 valves 31 tail tube A exhaust flow B Fluid force (negative pressure) C, E arrows D stagnation V flow velocity PL, PL 'plane c1 rotation axis c2 exhaust pipe center axis s1, s2 support α predetermined angle β, γ locus

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazumi Maeda             Nissan, Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan             Inside the automobile corporation F term (reference) 3G004 AA01 BA01 BA03 DA24 EA02

Claims (2)

[Claims] 1. A valve body is provided at an opening of an exhaust pipe of an exhaust silencer used in a vehicle so as to be rotatable about a predetermined rotation axis in a direction approaching the opening and a direction away from the opening. A vehicle exhaust muffler in which the valve body is rotatably biased in a direction of approaching the opening of the exhaust pipe to close the opening, wherein the opening of the exhaust pipe is larger than the inner diameter of the exhaust pipe. The valve body is provided with a seat surface corresponding to the shape of the enlarged diameter portion, and the rotation axis is inclined at a predetermined angle with respect to an imaginary plane orthogonal to the axis of the exhaust pipe. An exhaust muffler for vehicles, which is characterized in that 2. The exhaust silencer for a vehicle according to claim 1, wherein the rotation axis of the valve element is arranged upstream of the position of the valve element in the closed state in the exhaust flow direction.