JP3258554B2 - Automotive 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 exhaust muffler for reducing noise generated from an exhaust system of an automobile or the like.

[0002]

2. Description of the Related Art Conventional exhaust silencers for automobiles include:
For example, FIGS. 11 and 12 (Japanese Patent Application No. 6-32 filed by the present applicant)
No. 3336).

The inside of the muffler 1 has three baffle plates 6,
The first and second expansion chambers 2, 3, and 4 and the resonance chamber 5 are formed, respectively. An inlet tube 9 communicates with the first expansion chamber 2, and the second expansion chamber 2
The third expansion chamber 3 is connected to the atmosphere by a first tail tube 11 provided with a sound absorbing chamber 17 on the way. Also, the first expansion room 2
The third expansion chamber 4 communicates with the third expansion chamber 4 through an opening 13 and is provided with a valve 15 for opening and closing the opening 13 about a rotation shaft 14. Is connected to the outside by the second tail tube 12 having Further, the first expansion chamber 2 communicates with the resonance chamber 5 via the neck tube 16.

In the low engine speed region where the exhaust pressure introduced from the inlet tube 9 into the first expansion chamber 2 is low, the valve 15 is closed, and the exhaust gas is discharged from the first expansion chamber 2.
Is released to the atmosphere through the second expansion chamber 3 and the first tail tube 10. In this process, the pulsation of the exhaust gas is attenuated, and the resonance in the resonance chamber 5 communicated through the neck 16 reduces the frequency of the exhaust gas. Is attenuated. In the high engine speed region where the pressure of the exhaust gas rises, the valve 15 is opened, and then a part of the exhaust gas is released from the third expansion chamber 4 to the atmosphere via the second tail tube 12. As a result, the pulsation of the exhaust gas is attenuated, the passage resistance of the exhaust gas is reduced, and the exhaust loss in the high rotation region is reduced, thereby improving the engine output performance. In this way, the exhaust noise is effectively reduced from a low engine speed to a high engine speed, and a decrease in engine output in a high engine speed region is prevented.

On the other hand, a valve 1 that opens and closes according to the exhaust pressure
5 is a rotating shaft 14 supported by a nut 22 between bearings 21
, But is urged in a direction to close the opening 13 by the return spring 23, and a cushioning material 20 is provided to reduce the contact tapping sound accompanying the opening and closing of the valve 15. Especially in the operating range where the exhaust pressure is relatively low,
When the opening degree of the valve 15 is small, the valve 15 flaps in response to the pulsation of the exhaust gas, and collides with a part of the baffle plate 7 to generate a tapping sound. It is provided.

The hitting sound generated when the valve 15 comes into contact with the baffle plate 7 due to the pulsation of the exhaust gas is reduced by the cushioning material 20, but the flapping of the valve 15 causes the cushioning material 20 and There is a problem that the deterioration of the bearing 21 of the rotating shaft 14 is accelerated.

In order to prevent such a flapping phenomenon of the valve 15, a valve structure shown in FIGS. 13 and 14 can be considered. This is because a mass (mass body) 24 is added to the tip of the valve 15 and a valve closing force due to the weight of the mass 24 is not applied to the valve 15, so that the rotation direction of the valve 15 becomes horizontal. That is, the rotating shaft 14 is set in the vertical direction.

Now, this can be represented by a simplified model as shown in FIG. 15, where m is the mass of the mass 24, L is the length of the valve 15, g is the gravitational acceleration, and F is the force of the exhaust gas to push the valve 15 ( Input) and θ are the rotation angles of the valve, and the balance of the horizontal moment of the valve 15 is as follows.

[0009]

(Equation 1)

From the equation (1), the valve 1
The ratio of the rotational angular acceleration to the input of No. 5 is obtained.

[0011]

(Equation 2)

The ratio of the rotational acceleration to the input, which is obtained from the equation (2), indicates the degree of flapping of the valve 15, and becomes smaller as the mass 24 is heavier and the radius of rotation of the valve 15 is longer. Therefore, it can be seen that if the ratio is reduced by attaching the mass 24 to the tip of the valve 15, the flapping of the valve 15 is suppressed accordingly.

[0013]

However, when the valve 15 is rotated in the horizontal direction about the vertical rotation shaft 14 so that the weight of the mass 24 does not act on the valve closing force in this manner, the valve 15 A new problem arises in that the bending moment about the vertical axis acts on the bearing 21 due to the mass 24 located at the tip, and the deterioration of the bearing 21 is accelerated.

When the vehicle is in an accelerating state or a decelerating state,
Further, when climbing up or downhill, the component force of the weight of the mass 24 acts in the valve opening direction or the valve closing direction, so that the valve opening force set only by the spring force of the return spring 23 increases and decreases, and the valve 15 The opening / closing characteristics of the motor vary, and as a result, under such operating conditions, exhaust noise may deteriorate and output may decrease.

The present invention focuses on such a conventional problem, and by setting the center of gravity of the valve so as to be located substantially on the rotation axis of the valve, the fluttering of the valve is suppressed and the stability of the opening and closing operation is improved. It is also an object of the present invention to maintain a stable exhaust noise reduction function and engine output performance under all operating conditions.

[0016]

According to a first aspect of the present invention, there is provided a vehicle exhaust having a valve that opens and closes an opening provided in a baffle plate inside a muffler around a rotating shaft by the pressure of exhaust gas. In the noise reduction device, the rotation shaft is disposed near one end face of the opening, and the center of gravity of the valve is set to be substantially on the valve rotation shaft.

According to a second aspect of the present invention, a mass body is added to each end of both sides of the valve about the rotation axis.

According to a third aspect of the present invention, a return spring is provided which urges the valve in a valve closing direction by setting a rotation axis of the valve to be vertical.

According to a fourth aspect of the present invention, a return spring is provided for making the axial direction of the rotary shaft of the valve horizontal and for urging the valve in the valve closing direction.

According to a fifth aspect of the present invention, there is provided a valve, wherein the rotating shaft is disposed along one end face of the opening and is located substantially at the center of the thickness of the baffle plate, and the plate is attached to both sides of the rotating shaft. Is formed.

According to a sixth aspect of the present invention, a cutout is provided in a part of the valve opposite to the opening.

According to a seventh aspect of the present invention, there is provided a stopper for stopping the valve at the valve closing position when the engine is stopped, and the stopper is provided with a cushioning material.

[0023]

In the first aspect of the present invention, when the pressure of the exhaust gas increases, the valve rotates around the rotation axis and opens, but since the center of gravity of the valve is on the rotation axis, the balance about the rotation axis becomes poor. As a result, the fluttering of the valve is suppressed, the moment around the rotation axis is canceled, and the durability of the bearing supporting the rotation shaft is improved. In addition, the valve opening force does not fluctuate due to the valve's own weight even when the vehicle is accelerating or decelerating, or when traveling uphill or downhill, and the exhaust noise can be reduced and the output performance can be stably improved under all driving conditions. Is maintained.

According to the second aspect of the invention, the effect of suppressing the flapping of the valve is enhanced according to the size of the mass body disposed at both ends of the valve, and the opening and closing sound of the valve can be reduced and the durability can be improved.

In the third aspect of the invention, the rotation axis of the valve is vertical, preventing generation of a bending moment with respect to the rotation axis,
While maintaining smooth opening and closing of the valve, the durability of the bearing can be improved.

According to the fourth aspect of the present invention, the rotation axis of the valve is horizontal, and the weight of the valve can be evenly supported by the bearings on both sides, so that the durability of the bearing can be enhanced.

In the fifth aspect, since the valve is formed by fixing the plate members from both sides of the rotating shaft, the center of gravity of the valve can be accurately and easily set on the rotating shaft.

In the sixth aspect, the valve is provided with a notch on the side opposite to the opening, so that the fluid force due to the pressure and flow rate of the exhaust gas received by the valve in portions other than the flow rate control portion is reduced, and the valve is opened and closed. It can be done smoothly.

According to the seventh aspect, the valve is stopped by the stopper at the valve closing position, the occurrence of a tapping sound at the time of stop is suppressed, and the durability can be ensured.

[0030]

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

FIG. 1 shows a first embodiment of the present invention. In a muffler 1, a first expansion chamber 2, a second expansion chamber 3, and a resonance chamber 5 partitioned by baffle plates 6 and 7 are provided. Are formed, and an inlet tube 9 for introducing exhaust gas from an engine (not shown) is opened in the first expansion chamber 2.

Further, in order to release the introduced exhaust gas to the atmosphere, a first tail tube 11 provided with a sound absorbing chamber 17 in the middle is connected to the first expansion chamber 2, and the first expansion chamber 2 is connected to the first expansion chamber 2. The resonance chamber 5 is connected to each other via a neck tube 16.

An opening 13 is provided in the baffle plate 7 separating the resonance chamber 5 and the second expansion chamber 3. The opening 13 is provided when the engine is stopped or the exhaust pressure is low. The valve 15 is installed so as to close. The second expansion chamber 3 communicates with the atmosphere via a second tail tube 12 provided with a sound absorbing chamber 17 on the way.

Therefore, in the low engine speed region where the exhaust gas flow rate is low and the pressure is low, the exhaust gas introduced into the first expansion chamber 2 is discharged from the first tail tube 11 to the atmosphere, and pressure pulsation occurs in this process. Attenuated, and neck 1
While the low-frequency pulsating component is mainly attenuated by the function of the resonance chamber 5 communicating through the valve 6, the valve 15 is opened by the exhaust gas pressure and the valve 15 is partially opened in an engine high rotation region where the exhaust gas flow rate increases. The resonance chamber 5 is also released to the atmosphere through the opening 13, the second expansion chamber 3, and the second tail tube 12, and the resonance chamber 5 acts as an expansion element, and thereby, in the high engine speed region. And the exhaust passage resistance is reduced by opening the valve 15.

As described above, the exhaust noise can be effectively reduced from the low engine speed range to the high engine speed range, and the engine can exhibit high output performance in the high output operation range in which the displacement increases.

Next, details of the valve 15 which opens and closes according to the pressure of the exhaust gas are shown in FIGS.
5 is supported in a vertical direction by a pair of bearings 21 fixed to the baffle plate 7 so that an axis passes along one end face of the rectangular opening 13. Is wound around a folded portion 25 of a notch 26 formed at a position shifted from the center of the valve 15 to one side, and the valve 15 and the rotary shaft 14 are integrally connected. In this case, the space formed by the notch 26 is located outside the opening 13 so that the opening 13 is completely closed when the valve 15 is closed.

The valve 15 that rotates in the horizontal direction about the rotation shaft 14 is urged by a return spring 23 in a direction to close the opening 13.

[0038] Masses (mass bodies) 24 having substantially the same weight are provided at opposite ends of the valve 15 in opposite directions, respectively, so that the center of gravity of the entire valve 15 is located substantially on the rotating shaft 14. Thus, no bending moment is generated on the rotating shaft 14.

A stopper 27 is provided on a part of the rotary shaft 14 so that the valve 15 stops at a position where the valve 13 closes the opening 13 when the engine is stopped. In addition, between the stopper 27 and the baffle plate 7, a cushioning material or an impact relieving spring or the like is provided in order to prevent a hitting sound when the stopper 27 comes into direct contact with the baffle plate 7.

Next, the operation will be described.

The pressure of the exhaust gas acts on the valve 15 through the opening 13 from one side, and when this pressure becomes stronger than the urging force of the return spring 23, the valve 15 opens.
Part of the exhaust gas is released from the resonance chamber 5 to the second expansion chamber 3,
Further, it is released to the atmosphere via the second tail tube 12.

In this manner, the valve 15 opens and closes according to the pressure of the exhaust gas. Particularly, in an operation region where the exhaust pressure is relatively low and the opening of the valve 15 is small,
If there is a pulsation of the exhaust pressure, the valve 15 causes a flapping phenomenon such as opening and closing, and the tapping sound accompanying the contact is easily generated.

Therefore, the motion of the valve 15 will be analyzed.

For convenience of description, the valve 15 is represented by a simplified model as shown in FIG. 3, where m ₁ and m ₂ are mass of mass, L ₁ and L ₂ are length of the valve, and g is gravitational acceleration. , F is the force (input) of pushing the valve by the exhaust gas, and θ is the rotation angle of the valve, the balance of the moment in the horizontal direction is as follows.

[0045]

(Equation 3)

From this, the ratio of the rotational acceleration to the input, which indicates the degree of flapping of the valve 15, is obtained as follows.

[0047]

(Equation 4)

In the equation (4), if the valve 15 is now completely axially symmetric and m ₁ = m ₂ and L ₁ = L ₂ ,
The ratio of the rotational angular acceleration to the input is as follows.

[0049]

(Equation 5)

Further, if the inertia moment is the same even if the shape of the valve 15 is asymmetric, that is, if m ₁ L ₁ = m ₂ L ₂ ,
Similarly, the ratio of the rotational angular velocity to the input is as follows.

[0051]

(Equation 6)

That is, the ratio of the rotational angular acceleration to the input indicating the degree of flapping of the valve is expressed by equation (5) if the valve shape is completely axisymmetric, and the inertia moment is the same even if the valve shape is asymmetric. If there is, equation (6) is obtained, and it can be seen that the value becomes smaller as the mass 24 is heavier and the valve 15 is longer, so that the flapping of the valve 15 can be suppressed.

Therefore, by attaching the masses 24 to both ends of the valve 15 distant from the rotating shaft 14, flapping of the valve 15 can be suppressed as much as possible.

If the moment about the rotation axis 14 of the mass 24 around the rotation axis 14 is the same (m ₁ L ₁ = m ₂ L ₂ ), the moment around the vertical direction due to the own weight of the mass 24 cancels out. In the present invention, since the center of gravity of the valve 15 is set so as to be substantially on the rotation shaft 14,
The flapping of the valve 15 can be suppressed, and the moment around the vertical direction due to the weight of the mass 24 cancels out,
For this reason, no extra force acts on the bearing 21 and the durability of the bearing 21 is improved accordingly.

Also, when the vehicle is accelerating or decelerating, or when climbing or descending a hill, moments in the valve opening and valve closing directions due to the weight of the mass 24 are present on both sides of the rotary shaft 14 as a center. Since the two masses 24 cancel each other, the valve opening force set only by the spring force does not increase or decrease, and there is no problem that the exhaust noise reduction performance deteriorates or the output decreases.

FIGS. 4 and 5 show a second embodiment.

This is different from the first embodiment in that the rotation direction of the valve 15 is changed to the vertical direction.

That is, in this case, the rotary shaft 14 of the valve 15 is arranged to be horizontal, and the valve 15 rotates in the vertical direction around this. Other configurations are substantially the same as those of the first embodiment.

FIG. 6 shows a simplified model of the valve 15 as well, where m ₁ and m ₂ are the mass of the mass, L ₁ and L ₂ are the length of the valve, and g is the gravitational acceleration. , F is the force (input) of pushing the valve by the exhaust gas, and θ is the rotation angle of the valve, the balance of the vertical moment is
It becomes like the following formula.

[0060]

(Equation 7)

[0061]

(Equation 8)

Here, the valve 15 is completely axially symmetric (m ₁
= M ₂ , L ₁ = L ₂ ), the ratio of the rotational angular acceleration to the input representing the degree of flapping of the valve 15 is expressed by the following equation (9).

[0063]

(Equation 9)

Further, even if the shape of the valve 15 is asymmetric,
If the moments of inertia are the same (m ₁ L ₁ = m ₂ L ₂ ), the following equation (10) is obtained.

[0065]

(Equation 10)

That is, the ratio of the rotational angular acceleration to the input indicating the degree of flapping of the valve 15 is expressed by the following equation (8) or (9). As the length of the valve 15 becomes longer, the valve 15 becomes smaller, and the flapping of the valve 15 can be effectively suppressed accordingly.

In these cases, since the term of the gravitational acceleration is also eliminated, the influence of the moment around the vertical direction due to the weight of the mass 24 is also eliminated. That is, if the center of gravity of the valve is present on the rotating shaft 14, the flapping of the valve can be suppressed, and the moment around the vertical direction due to the own weight of the mass 24 cancels out. Can be improved in durability.

Further, in the first embodiment, since the valve 15 is rotated around the vertical
In this embodiment, the rotating shaft 14 of the valve 15 is horizontal, so that the bearings 21 on both sides can be evenly supported, and the durability of the bearing 21 is increased. Can be

Furthermore, as in the first embodiment, the center of the valve 15 is supported by the rotary shaft 14 when the vehicle is accelerating or decelerating, or when climbing or descending a hill. The moment in the valve opening and valve closing directions due to its own weight is canceled out, and the valve opening force set only by the spring force does not fluctuate, so that the exhaust noise can be reduced as always and the output can be secured as set.

FIGS. 7 and 8 show a third embodiment.

This is a modification of the method of fixing the valve 15 and the rotary shaft 14 according to the second embodiment. Section A
-A, a rotating shaft 1 having a circular or oval cross section as shown in FIG.
4 are arranged along the end face of the opening 13 and substantially at the center of the thickness of the baffle plate 7, and the plate members 15a, 1
5b are respectively attached by welding or the like to form the valve 15.

Since the rotating shaft 14 is disposed substantially at the center of the baffle plate 7, the baffle plate 7
Is provided with a semicircular recess 28 near the bearing 21 to prevent interference with the rotating shaft 14.

In this case, since the above-described folded portion 25 and notch 26 are not required, it is easy to accurately set the center of gravity of the valve 15 on the rotating shaft 14.

FIG. 9 and FIG. 10 are diagrams showing a fourth embodiment.

This corresponds to the baffle plate 7 of the third embodiment.
A hole 29 is formed by hollowing out the central portion of the valve 15 on the side opposite to the opening 13 provided at the bottom.

In this way, the exhaust gas is supplied to the valve 15.
When colliding, the hole 29 penetrates,
The air resistance in this portion is small for opening and closing the valve 15, so that the reverse rotation moment required when rotating the valve 15 is reduced, and the valve 15 can be opened with a small exhaust gas pressure.

[0077]

According to the first aspect of the present invention, since the center of gravity of the valve is on the rotation axis, a balance can be maintained around the rotation axis, the flapping of the valve can be suppressed, and the occurrence of tapping noise can be reduced. The moment around the rotating shaft is offset, the durability of the bearing that supports the rotating shaft is improved, and the valve opening force fluctuates due to the weight of the valve even when the vehicle is accelerating or decelerating, or traveling uphill or downhill. As a result, exhaust noise can be reduced and output performance can be stably improved under all operating conditions.

According to the second aspect of the present invention, the effect of suppressing the flapping of the valve is increased in accordance with the size of the mass body disposed at both ends of the valve, so that the opening and closing sound of the valve can be reduced and the durability can be improved.

According to the third aspect of the present invention, it is possible to prevent the occurrence of a bending moment with respect to the rotation axis, maintain smooth opening and closing of the valve, and improve the durability of the bearing.

According to the fourth aspect, the weight of the valve can be evenly supported by the bearings on both sides, so that the durability of the bearing can be enhanced.

According to the fifth aspect of the present invention, since the valve is formed by fixing the plate members from both sides of the rotating shaft, the center of gravity of the valve can be accurately and easily set on the rotating shaft.

According to the sixth aspect of the present invention, the notch provided on the side opposite to the opening reduces opening and closing of the valve in order to reduce the fluid force due to the pressure and flow rate of the exhaust gas received by the valve in portions other than the flow rate control portion. It can be done smoothly.

According to the seventh aspect of the invention, the valve is stopped by the stopper at the valve closing position, and the valve can be reliably closed. On the other hand, it is possible to suppress the occurrence of a tapping sound at the time of stopping and to ensure durability.

[Brief description of the drawings]

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

FIGS. 2A and 2B are detailed views of the valve, wherein FIG. 2A is a front view and FIG.

FIG. 3 is a simplified model diagram for analyzing motion of a valve.

FIG. 4 is a cross-sectional view showing a second embodiment.

5A and 5B are detailed views of the valve, wherein FIG. 5A is a front view and FIG. 5B is a cross-sectional view along AA.

FIG. 6 is a simplified model diagram for a motion analysis of the valve.

FIG. 7 is a sectional view showing a third embodiment.

8A and 8B are detailed views of the valve, wherein FIG. 8A is a front view, FIG. 8B is an AA cross-sectional view, and FIG. 8C is a BB cross-sectional view.

FIG. 9 is a cross-sectional view showing a fourth embodiment.

10A and 10B are detailed views of the valve, wherein FIG. 10A is a front view, FIG. 10B is an AA sectional view, and FIG. 10C is a BB sectional view.

FIG. 11 is a sectional view showing a conventional example.

FIG. 12 is a detailed view of the valve, wherein (A) is a front view and (B) is a cross-sectional view along AA.

FIG. 13 is a sectional view showing another example of the related art.

14A and 14B are detailed views of the valve, wherein FIG. 14A is a front view and FIG. 14B is a cross-sectional view along AA.

FIG. 15 is a simplified model diagram for the motion analysis of the valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Muffler 2 1st expansion room 3 2nd expansion room 4 3rd expansion room 5 resonance room 6 baffle plate 7 baffle plate 8 baffle plate 9 inlet tube 10 pass tube 11 1st tail tube 12 2nd tail tube 13 opening 14 rotation Shaft 15 Valve 20 Shock absorber 21 Bearing 23 Return spring 24 Mass 27 Stopper

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasuhiro Okamoto 5-24-15 Minamidai, Nakano-ku, Tokyo Inside Calsonic Corporation (56) References 1-80615, JP, U. Shosho 45 -12645 (JP, Y1) (58) Field surveyed (Int. Cl. ⁷ , DB name) F01N 1/02 F01N 1/08 F02D 9/04

Claims (7)

(57) [Claims] 1. An exhaust muffler for a vehicle, comprising: a valve that opens and closes an opening provided in a baffle plate inside a muffler around an axis of rotation by the pressure of exhaust gas. An exhaust muffler for an automobile, which is disposed near one end face of the vehicle and is set so that the center of gravity of the valve is located substantially on the valve rotation axis. 2. A vehicle exhaust silencer according to claim 1, wherein masses are respectively added to both end portions of the valve about the rotation axis. 3. The exhaust muffler for an automobile according to claim 1, wherein a return spring for biasing the valve in a valve closing direction is provided, with the axial direction of the rotary shaft of the valve being vertical. 4. An exhaust muffler for an automobile according to claim 1, wherein a return spring for biasing the valve in a valve closing direction is provided by setting a rotation axis of the valve in an axis direction horizontal. 5. The rotating shaft is disposed along one end face of the opening and substantially at the center of the thickness of the baffle plate,
6. The vehicle exhaust silencer according to claim 1, wherein the valve is formed by plate members attached to both sides of the rotating shaft. 6. The exhaust muffler for an automobile according to claim 1, wherein a cutout is provided in a part of the valve opposite to the opening. 7. The vehicle exhaust silencer according to claim 1, wherein a stopper is provided for stopping the valve at a valve closing position when the engine is stopped, and the stopper is provided with a cushioning material.