JPH10280939A - Muffler of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce noise satisfactorily in a low rotational region of an internal combustion engine, and simultaneously maintain output in its high rotational reason. SOLUTION: When an internal combustion engine is in a low rotational region, a flange 9 contacts with a valve seat 5 because energization force of a spring 7 overcomes exhaust gas pressure which the flange 9 receives, an outside exhaust gas path 13 which is formed from the outer peripheral face of a cylindrical part 8 and the inner peripheral face of a pipe 2 is shielded by the flange 9, and only inside exhaust gas path 14 which is formed from the inner peripheral face of the cylindrical part 8 is opened. When the internal combustion engine is in a high rotational region, the flange 9 is separated from the valve seat 5 because exhaust gas pressure which the flange 9 receives overcomes energization force of the spring 7, and the outside exhaust gas path 13 and the inside exhaust gas path 14 are both opened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a silencer for an internal combustion engine.

[0002]

2. Description of the Related Art As is well known, the exhaust system of an internal combustion engine is
Exhaust gas discharged from each cylinder is collected at an outlet manifold, and is configured to be discharged into the atmosphere through a catalyst and a muffler in order.

Here, the silencer generally includes a large-diameter main body and a small-diameter pipe disposed at the rear end of the main body, and reduces the output of the internal combustion engine while reducing noise due to exhaust gas. It is required that it not cause a decline.

[0004]

However, noise reduction and output maintenance are issues that have a so-called contradictory relationship.
According to the conventional silencer, it has been difficult to sufficiently reduce the noise in the low-speed rotation range of the internal combustion engine and at the same time maintain the output in the high-speed rotation range.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a silencer for an internal combustion engine that can simultaneously sufficiently reduce noise in a low-speed rotation range and maintain output in a high-speed rotation range. .

[0006]

According to the first aspect of the present invention, there is provided a silencer for an internal combustion engine having a small-diameter pipe at the rear end of a large-diameter main body. An exhaust gas flow path adjusting mechanism that adjusts a cross-sectional area of the exhaust gas flow path in accordance with the exhaust gas pressure is provided in the pipe section.

[0007] A silencer for an internal combustion engine according to the present invention comprises:
As described in claim 2, in claim 1, the exhaust gas flow path adjustment mechanism reduces a cross-sectional area of the exhaust gas flow path when the internal combustion engine is in a low speed rotation range, and the internal combustion engine is in a high speed rotation range. It is characterized in that the cross-sectional area of the exhaust gas passage is increased.

[0008] Further, a silencer for an internal combustion engine according to the present invention comprises:
According to a third aspect, in the second aspect, the exhaust gas flow path adjustment mechanism includes a partition and an opening / closing door, and the partition has a direction perpendicular to a flow of the exhaust gas in the pipe portion. In the above, the door is divided into a plurality of exhaust gas flow path elements, and the opening and closing door is provided corresponding to the exhaust gas flow path element divided by the partition, and opens the exhaust gas flow path element by the exhaust gas pressure. Features.

[0009] A silencer for an internal combustion engine according to the present invention comprises:
As described in claim 4, in claim 3, the exhaust gas flow path adjusting mechanism includes a valve body, a valve seat, a holder, and a spring, and the valve body is a hollow cylinder forming the partition. And a flange that constitutes the opening / closing door, wherein the cylindrical portion is disposed with a gap with an inner peripheral surface of the pipe portion and in an axial direction along a flow direction of the exhaust gas, and the flange is provided with an exhaust gas. The valve seat protrudes outward from the cylindrical portion so as to be able to receive pressure, the valve seat is protruded from the inner peripheral surface of the pipe portion so as to be able to abut against a flange of the valve body, and the holder Holds the tubular portion so that the tubular portion of the valve body can reciprocate in the flow direction of the exhaust gas, and the spring has a cylindrical shape of the valve body between the flange of the valve body and the holder. The internal combustion engine is located in the low speed range. Is in a state where the urging force of the spring overcomes the exhaust gas pressure received by the flange and the flange abuts on the valve seat, and is formed by an outer peripheral surface of the cylindrical portion and an inner peripheral surface of the pipe portion. The outer exhaust gas passage formed is blocked by the flange, and only the inner exhaust gas passage formed by the inner peripheral surface of the cylindrical portion is in an open state. The exhaust gas pressure received by the spring overcomes the biasing force of the spring, the flange is separated from the valve seat, and the outer exhaust gas passage and the inner exhaust gas passage are both open. And

[0010] A silencer for an internal combustion engine according to the present invention comprises:
As described in claim 5, in claim 4, the holder is mounted on a tubular portion of the valve body, the collar being slidably holding the tubular portion, and the pipe portion is formed from the collar. A plurality of stays extending radially toward the inner peripheral surface of the valve body and fixed to the pipe portion by bolts, wherein the spring is provided between a rear side of the flange of the valve body and a front side of the collar of the holder. It is characterized by being arranged in a compressed state.

[0011] A silencer for an internal combustion engine according to the present invention comprises:
According to a sixth aspect of the present invention, in the fourth or fifth aspect, the flange is provided with a concave portion for receiving the exhaust gas pressure and rotating the valve body.

Further, a silencer for an internal combustion engine according to the present invention comprises:
As described in claim 7, in claim 5 or claim 6, a concave ridge that does not contact the outer peripheral surface of the cylindrical portion is formed on the inner peripheral surface of the collar along the axial direction. It is characterized by the following.

[0013]

According to the first aspect of the present invention,
Since the cross-sectional area of the exhaust gas passage is adjusted according to the exhaust gas pressure by the exhaust gas passage adjusting mechanism, the cross-sectional area of the exhaust gas passage in the low-speed rotation region of the internal combustion engine and the exhaust gas passage in the high-speed rotation region By setting the cross-sectional areas to appropriate values, it is possible to simultaneously achieve sufficient reduction of noise in the low-speed rotation range and maintenance of output in the high-speed rotation range.

Further, according to the present invention described in claim 2,
Since the cross-sectional area of the exhaust gas passage decreases when the internal combustion engine is in the low-speed rotation range, it is possible to sufficiently reduce noise in the low-speed rotation range. In addition, due to the decrease in the cross-sectional area of the exhaust gas passage, the exhaust gas pressure (back pressure) in the outlet manifold in the low-speed rotation region is increased, and the flow rate of the exhaust gas can be reduced. The effects described can also be expected. That is, as is well known, during the transition from the exhaust stroke to the intake stroke of the internal combustion engine, a valve overlap period occurs in which both the exhaust valve and the intake valve are open. A part of the mixture of fuel and air that has flowed into the exhaust manifold leaks to the outlet manifold in such a manner as to be sucked into the flow of exhaust gas, and this causes a decrease in torque. However, in the present invention, since the flow rate of the exhaust gas in the low-speed rotation region is reduced, the amount of the air-fuel mixture leaking to the outlet manifold is reduced, so that a sufficient amount of the air-fuel mixture remains in the cylinder, and therefore, It is possible to increase the torque in the low speed rotation range.

Further, according to the present invention, when the internal combustion engine is in a high-speed rotation region, the cross-sectional area of the exhaust gas flow path increases, so that the output in the high-speed rotation region is maintained by reducing the exhaust resistance. Can be expected, and an increase in output can be expected.

Further, according to the present invention described in claim 3,
The exhaust gas flow path adjusting mechanism includes a partition and an opening / closing door, and the partition divides the inside of the pipe portion into a plurality of exhaust gas flow elements in a direction orthogonal to the flow of the exhaust gas. Since the exhaust gas flow path element is provided corresponding to the divided exhaust gas flow path element and is configured to be opened by the exhaust gas pressure, at least one opening / closing door must be closed in a low-speed rotation range of the internal combustion engine. As a result, exhaust gas stops flowing through the exhaust gas flow path element, and the cross-sectional area of the exhaust gas flow path can be reduced. Exhaust gas flows, and the cross-sectional area of the exhaust gas passage can be increased. Therefore, it is possible to sufficiently reduce the noise and increase the torque in the low-speed rotation range of the internal combustion engine, and to maintain or increase the output in the high-speed rotation range.

Further, according to the present invention described in claim 4,
When the internal combustion engine is in the low-speed rotation range, the biasing force of the spring overcomes the exhaust gas pressure received by the flange, the flange is in contact with the valve seat, and the outer peripheral surface of the cylindrical portion and the inner peripheral surface of the pipe portion are in contact with each other. The outer exhaust gas flow path formed by the flange is blocked by the flange, and only the inner exhaust gas flow path formed by the inner peripheral surface of the cylindrical portion is in an open state, so that the cross-sectional area of the exhaust gas flow path is reduced. Therefore, as described above, it is possible to sufficiently reduce noise and increase torque in the low-speed rotation range.

Further, according to the present invention, when the internal combustion engine is in a high speed rotation range, the exhaust gas pressure received by the flange overcomes the urging force of the spring, and the flange is separated from the valve seat. Since the outer exhaust gas passage and the inner exhaust gas passage are both open, the cross-sectional area of the exhaust gas passage increases, and therefore, as described above, the output is maintained in the high-speed rotation region. Alternatively, it can be increased.

Further, according to the present invention described in claim 5,
The holder is annularly mounted on the tubular portion of the valve body and slidably holds the tubular portion. The collar extends radially from the collar toward the inner peripheral surface of the pipe portion, and is fixed to the pipe portion by bolts. Consisting of multiple stays, the spring is arranged in a compressed state between the rear side of the flange of the valve body and the front side of the collar of the holder. Can be.

Further, according to the present invention described in claim 6,
Since the valve body rotates when the recess formed in the flange receives the exhaust gas pressure, the problem that the flange is seized on the valve seat by the relatively high temperature exhaust gas and the cross-sectional area of the exhaust gas passage cannot be adjusted is prevented. it can.

According to the present invention as set forth in claim 7,
Because a gap is formed between the inner peripheral surface of the collar and the outer peripheral surface of the cylindrical portion by the concave streak formed on the inner peripheral surface of the collar,
It is possible to prevent a problem that the cylindrical portion is seized on the collar by the relatively high temperature exhaust gas and the cross-sectional area of the exhaust gas channel cannot be adjusted.

[0022]

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

FIG. 1 is a cross-sectional view of a main part of a silencer of an internal combustion engine according to an embodiment, showing a state where the internal combustion engine is in a low-speed rotation range, and FIG. 2 is a main part of the silencer. FIG. 3 is a cross-sectional view showing a state when the internal combustion engine is in a high-speed rotation range, and FIG. 3 is a rear view of the silencer.

The silencer according to this embodiment includes a large-diameter main body 1 connected to a catalyst (not shown), and a pipe 2 disposed at the rear end of the main body 1. A gas flow path adjusting mechanism 3 is provided.

The exhaust gas flow path adjusting mechanism 3 includes a valve body 4, a valve seat 5, a holder 6, and a spring 7.

The valve body 4 has a hollow cylindrical portion 8 (partition wall) and a flange 9 (opening / closing door).

The cylindrical portion 8 is disposed with a gap with the inner peripheral surface of the pipe portion 2 and with the axial direction along the flow direction of the exhaust gas.

The flange 9 is provided so as to protrude outward from the cylindrical portion 8 so as to be able to receive the exhaust gas pressure.

The valve seat 5 protrudes from the inner peripheral surface of the pipe portion 2 so as to be able to contact the flange 9 of the valve body 4.

The holder 6 is annularly mounted on the cylindrical portion 8 of the valve body 4 and slidably holds the cylindrical portion 8. The collar 10 radially extends from the collar 10 toward the inner peripheral surface of the pipe portion 2. It comprises a plurality of stays 12, 12, 12 which are extended and fixed to the pipe portion 2 by bolts 11. Therefore, the holder 6 holds the tubular portion 8 so that the tubular portion 8 of the valve body 4 can reciprocate in the flow direction of the exhaust gas.

The spring 7 is arranged in a compressed state so as to surround the cylindrical portion 8 of the valve body 4 between the rear side of the flange 9 of the valve body 4 and the front side of the collar 10 of the holder 6. In other words, the spring 7 is connected to the flange 9 of the valve body 4 and the holder 6.
Is disposed so as to wrap the tubular portion 8 of the valve body 4 between the valve body 4 and the valve body 4.

In the silencer configured as described above,
When the internal combustion engine is in the low speed rotation range, as shown in FIG. 1, the urging force of the spring 7 overcomes the exhaust gas pressure received by the flange 9 and the flange 9 is in contact with the valve seat 5,
An outer exhaust gas passage 13 (exhaust gas passage element) formed by the outer peripheral surface of the cylindrical portion 8 and the inner peripheral surface of the pipe portion 2 is blocked by the flange 9 and formed by the inner peripheral surface of the cylindrical portion 8. Only the inner exhaust gas passage 14 (exhaust gas passage element) to be operated is in an open state.

On the other hand, when the internal combustion engine is in the high-speed rotation region, as shown in FIG. 2, the exhaust gas pressure received by the flange 9 overcomes the urging force of the spring 7 and the flange 9 is separated from the valve seat 5. The outer exhaust gas passage 13 and the inner exhaust gas passage 14 are both open.

As described above, according to the muffler of the present embodiment, the cross-sectional area of the exhaust gas passage is reduced when the internal combustion engine is in the low-speed rotation range, so that the noise in the low-speed rotation range is sufficiently reduced. be able to. In addition, due to the decrease in the cross-sectional area of the exhaust gas passage, the exhaust gas pressure (back pressure) in the outlet manifold in the low-speed rotation region is increased, and the flow rate of the exhaust gas can be reduced. The effects described can also be expected. That is, as is well known, a valve overlap period occurs in which both the exhaust valve and the intake valve are open during the transition from the exhaust stroke to the intake stroke of the internal combustion engine, and during this valve overlap period,
Part of the mixture of fuel and air that has flowed into the cylinder leaks to the outlet manifold in such a manner as to be attracted to the flow of the exhaust gas, which causes a reduction in torque. However, in the present embodiment, since the flow rate of the exhaust gas in the low-speed rotation region decreases, the amount of the air-fuel mixture leaking to the outlet manifold decreases, and a sufficient amount of the air-fuel mixture remains in the cylinder. Thus, it is possible to increase the torque in the low-speed rotation range.

Further, according to the present embodiment, when the internal combustion engine is in the high-speed rotation range, the cross-sectional area of the exhaust gas flow path increases.
Due to the reduction of the exhaust resistance, the output in the high-speed rotation region can be maintained, and the output can be expected to increase.

Further, according to the present embodiment, the exhaust gas flow path adjusting mechanism 3 includes a partition (cylindrical portion 8) and an opening / closing door (flange 9).
The partition 8 divides the inside of the pipe portion 2 into a plurality of exhaust gas flow path elements (inner exhaust gas flow path 14 and outer exhaust gas flow path 13) in a direction orthogonal to the flow of the exhaust gas, and The door 9 is provided corresponding to the exhaust gas flow path element 13 divided by the partition wall 8 and is configured to open the exhaust gas flow path element 13 by the exhaust gas pressure. By closing at least one opening / closing door 9, exhaust gas does not flow through the exhaust gas passage element 13 and the cross-sectional area of the exhaust gas passage can be reduced. 9 to open the exhaust gas flow path element 13
As a result, the exhaust gas flows through the exhaust gas passage, and the cross-sectional area of the exhaust gas passage can be increased. Therefore, it is possible to sufficiently reduce the noise and increase the torque in the low-speed rotation range of the internal combustion engine, and to maintain or increase the output in the high-speed rotation range.

Further, according to the present embodiment, when the internal combustion engine is in the low speed rotation range, the urging force of the spring 7 overcomes the exhaust gas pressure received by the flange 9 so that the flange 9 is in contact with the valve seat 5. The outer exhaust gas passage 13 formed by the outer peripheral surface of the cylindrical portion 8 and the inner peripheral surface of the pipe portion 2
Is cut off, and only the inner exhaust gas passage 14 formed by the inner peripheral surface of the cylindrical portion 8 is in an open state, so that the cross-sectional area of the exhaust gas passage is reduced. , Noise can be sufficiently reduced, and torque can be increased.

Further, according to the present embodiment, when the internal combustion engine is in the high-speed rotation range, the exhaust gas pressure received by the flange 9 overcomes the urging force of the spring 7 and the flange 9 is separated from the valve seat 5; Since both the outer exhaust gas passage 13 and the inner exhaust gas passage 14 are in the open state, the cross-sectional area of the exhaust gas passage increases, and therefore, the output is maintained or increased in the high-speed rotation range. be able to.

According to the present embodiment, the holder 6
A collar 10 wrapped around the tubular portion 8 of the valve body 4 and slidably holding the tubular portion 8, extending radially from the collar 10 toward the inner peripheral surface of the pipe portion 2, The spring 7 is arranged in a compressed state between the rear side of the flange 9 of the valve body 4 and the front side of the collar 10 of the holder 6, so that the spring 7 has a very simple configuration. Thus, the exhaust gas flow path adjusting mechanism 3 can be configured.

In the above embodiment, the cylindrical portion 8 is cylindrical. However, the shape of the cylindrical portion 8 is not limited to a cylindrical shape, but may be other shapes such as a square shape and an elliptical shape. You may. The number of the stays 12 is not limited to three, and may be any number as long as it is plural. In the above embodiment, the exhaust gas flow path element 13 is opened and closed at the front of the pipe section 2. However, the exhaust gas flow path element 13 can be opened and closed at the rear of the pipe section 2. is there.

FIG. 4 is a cross-sectional view of a main part of a muffler according to another embodiment, showing a state where the internal combustion engine is in a low-speed rotation range. FIG. 5 is a front view of a flange of a valve body. FIG.
Shows rear views of the holder.

The embodiment shown in FIGS. 4 to 6 corresponds to FIGS.
As shown in the figure, a plurality of recesses 9a are formed in the flange 9 of the valve body 4,
9a, 9a are provided at equal intervals in the circumferential direction. These recesses 9a, 9a, 9a are formed with a predetermined inclination with respect to the radial direction so that when the exhaust gas pressure is received, the valve body 4 can be rotated in a certain direction, for example, in the direction of arrow a shown in FIG. . Therefore, since the valve element 4 becomes rotatable when the flange 9 receives the exhaust gas pressure, the flange 9 sticks to the valve seat 5 due to the relatively high-temperature exhaust gas and the cross-sectional area of the exhaust gas passage cannot be adjusted. Occurrence can be prevented.

Further, in this embodiment, as shown in FIGS. 4 and 6, the inner peripheral surface 10a of the collar 10 of the holder 6 is
A plurality of ridges 10b, 10b, 10b along the axial direction are provided at equal intervals in the circumferential direction, and these ridges 10b, 10b,
b, 10b, the inner peripheral surface 10a of the collar 10
A gap is positively formed between the outer peripheral surface 8a of the tubular portion 8 of the valve body 4 and the outer peripheral surface 8a. Therefore, the formation of these gaps can prevent a problem that the tubular portion 8 is seized on the collar 10 by the relatively high-temperature exhaust gas and the cross-sectional area of the exhaust gas passage cannot be adjusted.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of a silencer of an internal combustion engine according to an embodiment, showing a state when the internal combustion engine is in a low-speed rotation range.

FIG. 2 is a cross-sectional view of a main part of the silencer, showing a state when the internal combustion engine is in a high-speed rotation range.

FIG. 3 is a rear view of the muffler.

FIG. 4 is a cross-sectional view of a main part of a silencer of an internal combustion engine according to another embodiment, showing a state when the internal combustion engine is in a low-speed rotation range.

FIG. 5 is a front view of a flange of a valve body of the silencer.

FIG. 6 is a rear view of the holder of the silencer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body part 2 Pipe part 3 Exhaust gas flow path adjustment mechanism 4 Valve body 5 Valve seat 6 Holder 7 Spring 8 Cylindrical part (partition) 8a Outer peripheral surface 9 Flange (opening / closing door) 9a Recess 10 Collar 10a Inner peripheral surface 10b Concave stripe Part 11 Bolt 12 Stay 13 Outer exhaust gas passage (exhaust gas passage element) 14 Inner exhaust gas passage (exhaust gas passage element)

Claims (7)

[Claims] 1. A silencer for an internal combustion engine having a small-diameter pipe portion at a rear end of a large-diameter main body portion, wherein a cross-sectional area of an exhaust gas passage is adjusted in the pipe portion according to exhaust gas pressure. A silencer for an internal combustion engine, comprising an exhaust gas flow path adjusting mechanism. 2. The exhaust gas passage adjusting mechanism reduces a cross-sectional area of the exhaust gas passage when the internal combustion engine is in a low speed rotation range,
The muffler for an internal combustion engine according to claim 1, wherein the cross-sectional area of the exhaust gas passage is increased when the internal combustion engine is in a high-speed rotation range. 3. The exhaust gas flow path adjusting mechanism includes a partition and an opening / closing door, and the partition divides the inside of the pipe portion into a plurality of exhaust gas flow elements in a direction orthogonal to the flow of exhaust gas. The internal combustion engine according to claim 2, wherein the opening / closing door is provided corresponding to an exhaust gas flow path element divided by the partition, and opens the exhaust gas flow path element by exhaust gas pressure. Institution silencer. 4. The exhaust gas flow path adjusting mechanism includes a valve element, a valve seat, a holder, and a spring, and the valve element has a hollow cylindrical portion forming the partition and a flange forming the opening / closing door. The cylindrical portion is disposed with a gap with the inner peripheral surface of the pipe portion and along the axial direction in the flow direction of the exhaust gas, and the flange is configured to receive the exhaust gas pressure. The valve seat protrudes from the inner peripheral surface of the pipe portion so as to be able to contact the flange of the valve body, and the holder is configured such that the cylindrical portion of the valve body is exhausted. An internal combustion engine that holds the cylindrical portion so as to be able to reciprocate in a gas flow direction, and that the spring wraps the cylindrical portion of the valve body between a flange of the valve body and the holder; Is in the low speed range, the biasing force of the spring is An outer exhaust gas passage formed by an outer peripheral surface of the cylindrical portion and an inner peripheral surface of the pipe portion is in a state in which the flange is in contact with the valve seat overcoming the exhaust gas pressure received by the flange. When the internal combustion engine is in a high speed range, the exhaust gas pressure received by the flange is reduced by the spring. 4. The flange according to claim 3, wherein the flange is separated from the valve seat by overcoming the biasing force, and both the outer exhaust gas passage and the inner exhaust gas passage are open. Silencer for internal combustion engine. 5. The collar is mounted on a tubular portion of the valve body and slidably holds the tubular portion. The holder extends radially from the collar toward an inner peripheral surface of the pipe portion. ,
A plurality of stays fixed to the pipe portion by bolts, wherein the spring is arranged in a compressed state between a rear side of the flange of the valve body and a front side of the collar of the holder. The muffler for an internal combustion engine according to claim 4. 6. The muffler for an internal combustion engine according to claim 4, wherein a recess is formed in the flange to rotate the valve body in response to an exhaust gas pressure. 7. The collar according to claim 5, wherein a concave ridge that does not contact the outer peripheral surface of the cylindrical portion is formed on the inner peripheral surface of the collar along the axial direction. Internal combustion engine silencer.