JP3017963B2 - Silencer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silencer used for an internal combustion engine such as an automobile engine.

[0002]

2. Description of the Related Art Conventionally, at the time of a high-speed large exhaust flow rate of an internal combustion engine, reduction of back pressure has been emphasized to improve the output, and at the time of low-speed small exhaust flow rate, emphasis has been placed on the noise reduction effect over the back pressure. As a silencer, for example, the one shown in FIG. 9 is disclosed in Japanese Utility Model Publication No. 2-18265.

The silencer shown in FIG. 9 divides an outer shell 100 into a first chamber 101, a second chamber 102, and a third chamber 103, and an exhaust inlet pipe 104 communicating with the first chamber 101 through a small hole 105. Is provided in the second chamber 102 so as to be open, and a small hole 10 is provided in the second chamber 102.
The communication pipe 107 communicated with the first chamber 101 and the third chamber 10
3, a first exhaust outlet pipe 109 communicating with the third chamber 103 through a small hole 108, and an inner end of the first exhaust outlet pipe 109 is connected to the first chamber 101.
The tail pipe 110 is connected to the outer end, and a throttle valve 111 is provided between the first exhaust outlet pipe 109 and the tail pipe 110.

Further, a second exhaust upstream pipe 112 penetrating the first chamber 101 and the second chamber 102 is provided, an exhaust inlet end thereof is opened to the third chamber 103, and a U-shaped downstream end of the upstream pipe 112 is provided. The second exhaust downstream pipe 113 is formed by connecting the second exhaust downstream pipe 113 having a shape.
13 is arranged in a state where the outer side of the outer shell 100 is U-turned, and its downstream end is joined at a downstream portion of the throttle valve 111.

The throttle valve 111 is an electromagnetic valve. The throttle valve 111 detects the engine speed and the control circuit 115 opens the throttle valve 111 when the engine is running at high speed.
When the engine is running at a low speed, the throttle valve 111 is closed.

When the engine rotates at a high speed, the throttle valve 11
1, the back pressure is reduced by discharging the exhaust gas flowing from the exhaust inlet pipe 104 through the large-diameter first exhaust outlet pipe 109, and the throttle valve 111 is operated at a low rotation speed.
, The exhaust gas flowing from the exhaust inlet pipe 104 is discharged through the second exhaust outlet pipe 114 having a small diameter and a long length, thereby improving the noise reduction performance.

[0007]

However, in the above conventional silencer, when the diameter of the second exhaust outlet pipe 114 is set to be large, a sufficient back pressure cannot be applied,
Insufficient volume reduction at low rpm. Further, when the diameter of the second exhaust outlet pipe 114 is set to be small, there is a problem that an increase in exhaust gas flow rate causes an increase in airflow noise (500 Hz or more) and an increase in back pressure. It is necessary to switch the throttle valve 111 by rotation, and in any case, it is difficult to achieve sufficient silencing and low back pressure over the entire area.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a silencer capable of sufficiently suppressing noise and controlling the back pressure in each of the low, middle, and high engine speed ranges. is there.

[0009]

The present invention SUMMARY OF] In order to solve the above problems, a first invention according to claim 1, Rutotomoni upstream comprises a first open-close means opens into the muffler, the downstream
A first exhaust outlet pipe having a side open to the outside of the muffler has a smaller diameter than the first exhaust outlet pipe and a length suitable for silencing in a low engine speed range, and one end opens into the muffler.
The second and the other end of the exhaust outlet pipe, in that are merged in the downstream of the first opening and closing means, communicating with the upstream side of the chamber from the chamber and the chamber exhaust inlet of said first exhaust outlet pipe is opened and And a second opening / closing means for opening / closing the communication pipe. The bypass pipe is set to have a smaller diameter than the communication pipe, and both of the opening / closing means are closed in a low rotation range.
In the middle rotation range, the first opening / closing means is opened, and in the high rotation range,
Is characterized by further opening the second opening / closing means .

In the present invention, in the low engine speed range, both the first opening / closing means and the second opening / closing means are closed, and the exhaust gas flows through the bypass pipe into the second exhaust outlet pipe. After flowing through the second exhaust outlet pipe, it is discharged to the outside from the junction through the first exhaust outlet pipe.

As described above, the exhaust gas flows through the second exhaust outlet pipe, so that the noise reduction performance in the low engine speed range of the engine can be improved. In the middle rotation range of the engine,
The first opening / closing means operates to open, and the second opening / closing means remains closed. Therefore, the exhaust gas is discharged mainly after flowing through the large-diameter first exhaust outlet pipe after flowing through the bypass pipe, and an increase in the back pressure is prevented.

In the high speed range of the engine, both the first opening / closing means and the second opening / closing means are in an open state, and are discharged from the large-diameter first exhaust outlet pipe mainly through the large-diameter communication pipe from the bypass pipe. You. Therefore, an increase in back pressure is prevented.

Further, in the entire rotation range, the sound is also silenced by the resonance chamber and the expansion chamber formed by the respective chambers in which the respective tubes open. According to a second aspect of the present invention, in the first aspect, the entire length of the second exhaust outlet pipe is set shorter than the entire length of the first exhaust outlet pipe.

In the present invention, since the total length of the second exhaust outlet pipe is shorter than the total length of the conventional second exhaust outlet pipe, the air column is formed by the second exhaust outlet pipe in a region equal to or higher than the middle rotation region of the engine. No abnormal noise occurs due to resonance.

According to a third aspect of the present invention, in the first or second aspect, the exhaust inlet of the communication pipe is opened to a chamber which becomes a resonance chamber when the second opening / closing means is closed. is there. In the present invention, when the chamber in which the exhaust inflow port of the communication pipe is opened becomes a resonance chamber in the low and middle rotation range of the engine, and the second opening / closing means of the communication pipe is opened in the high rotation range of the engine,
Changed to an expansion room. Therefore, in the high rotation range, the sound reduction due to the expansion increases.

According to a fourth aspect of the present invention, in the first, second or third aspect, the first opening / closing means and the second opening / closing means are each provided with an exhaust gas inlet of each pipe. The opening operation is performed by the exhaust gas pressure.

In the present invention, the first opening / closing means and the second opening / closing means are automatically opened by the set exhaust gas pressure. The fifth invention according to claim 5 is the fourth invention.
In the invention, the first opening / closing means and the second opening / closing means are each constituted by a butterfly valve element which is opened by exhaust gas pressure, and a coil spring for urging the valve element in a closing direction.

In the present invention, by setting the urging force of the coil spring of the second opening / closing means to be stronger than the urging force of the coil spring of the first opening / closing means, the second opening / closing means is opened after the first opening / closing means is opened. Can be activated. Therefore, the first opening / closing means and the second opening / closing means can be configured by simply changing the winding amount when assembling the coil spring using the same components.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the embodiments shown in FIGS. 1 to 7 show a first embodiment.

In FIG. 1, the front and rear sides of an outer cylinder 1 constituting a silencer are closed by front and rear side walls 2 and 3, and the inside of the outer cylinder 1 is divided into a plurality of chambers. It is partitioned into a first room 6, a second room 7, and a third room 8.

An exhaust inlet pipe 9 is provided so as to penetrate the first chamber 6 and the second chamber 7 from the front side wall 2 and communicate with the third chamber 8 to be opened.
Its upstream end communicates with the exhaust pipe of the engine. The exhaust inlet pipe 9 has a first small hole 10 communicating with the first chamber 6 and a second small hole 11 communicating with the second chamber 7.

The first exhaust outlet pipe 12 is formed to have a large diameter that does not increase the back pressure in a high engine speed range, and penetrates the second chamber 7 and the third chamber 8 and communicates upstream with the first chamber 6. It is open and the downstream side is open outside the silencer. A first opening / closing means 13 is provided at an opening end of the first exhaust outlet pipe 12 on the first chamber 6 side, and the first exhaust outlet pipe 12 communicates with the first chamber 6 by opening and closing the valve body 13a. Or to shut off.

The first opening / closing means 13 is, as shown in FIG.
Case 1 in which a flow passage having the same diameter as first exhaust outlet pipe 12 is formed
3b, a butterfly-type valve body 13a having an eccentric rotary shaft 13c, a coil spring 13f as a biasing means provided between a spring receiving portion 13d of the rotary shaft 13c and a spring stopper 13e fixed to the case 13b. , A valve stopper 13g fixed in the case 13b, and when the exhaust gas pressure in the first chamber 6 reaches a predetermined value, the valve body 1
When the pressure acting on the coil spring 3a becomes larger than the set urging force of the coil spring 13f, the coil spring 13f is involved and the valve is opened. When the exhaust gas pressure in the first chamber 6 becomes equal to or less than a predetermined value, the valve is closed by the urging force of the coil spring 13f, and the closed state is maintained by the valve stopper 13g.

A small hole is formed in the third chamber 8 of the first exhaust outlet pipe 12, and a silencer chamber 15 formed by winding a glass wool 14 around the small hole is formed. A communication pipe 16 for communicating the first chamber 6 and the second chamber 7 is fixed to the partition wall 4. A second opening / closing means is provided at an open end of the communication pipe 16 on the first chamber 6 side. The communication pipe 16 and the first chamber 6 are communicated or blocked by opening and closing the valve body 17a.

As shown in FIG. 3, the second opening / closing means 17 has a case 17b forming a flow passage having the same diameter as the communication passage 16.
, A butterfly type valve element 17a provided with an eccentric rotation shaft 17c, and a spring receiver 17d of the rotation shaft 17c
A coil spring 17f as urging means provided between a spring stopper 17e fixed to the case 17b and the case 17b;
b, and a valve stopper 17g fixed inside
When the exhaust gas pressure in the chamber 6 becomes a predetermined value and the pressure acting on the valve element 17a becomes larger than the set urging force of the coil spring 17f, the coil spring 17f is wound up and the valve is opened. When the exhaust gas pressure in the first chamber 6 becomes equal to or higher than a predetermined value, the valve is closed by the urging force of the coil spring 17f, and the closed state is maintained by the valve stopper 17g.

Therefore, the first opening / closing means 13 and the second
Both the opening and closing means are formed of the same component. The urging force of the coil spring 17f in the second opening / closing means 17 is set to be stronger than the urging force of the coil spring 13f in the first opening / closing means 13. The position of the spring receiver 13d of the first opening / closing means 13 and the position of the spring receiver 17d of the second opening / closing means 17 are adjusted by using
Entrainment amount theta ₂ of the coil spring 17f of 7, is set to be larger than the winding amount theta ₁ of the coil spring 13f in the first opening and closing means 13 in the closed state.

More specifically, each of the coil springs 13
When the engine is stopped and the engine speed is low (0 to 1500 rpm), the urging force of the valve body 1 of the first opening / closing means 13 is increased.
3a and the valve element 17a of the second opening / closing means 17 are both closed by a spring force, and the engine is rotated in the middle rotation range (from 1500 to 2500 rpm).
m), the valve body 13a of the first opening / closing means 13 opens against the spring force, but the valve body 17a of the second opening / closing means 17 is in the closed state by the spring force, and the engine rotates at a high rotational speed range (2500 rpm).
In the above, the valve 13a of the first opening / closing means 13 and the valve 17a of the second opening / closing means 17 are both set to open.

A second exhaust outlet pipe 18 is fixed to the front side wall 2. The second exhaust outlet pipe 18 is bent in a U-shape, and its bent portion 18 a is positioned outside the front side wall 2. One end 18b thereof communicates with the first chamber 6 through an opening, and the other end 18c is joined to the first exhaust outlet pipe 12 at a position downstream of the first opening / closing means 13.

A bypass pipe 19 is fixed to the partition wall 4, one end of which is open to the first chamber 6, and the other end of which is open to the second chamber 7. Furthermore, the overall length L ₁ of the second exhaust outlet pipe 18 has been set to a length suitable for silencing the low rotation speed region of the engine, preferably the first exhaust outlet pipe 1
Substantially equal it may be set or two shorter than the total length L _2. In the embodiment shown in the drawing, the length of the first exhaust outlet pipe 12 is shorter than the total length L ₂ , and from the junction A of the first exhaust outlet pipe 12 with the second exhaust outlet pipe 18, the exhaust inlet end of the first exhaust outlet pipe 12. It is set to be longer than the length L ₃ of up to.

[0030] In addition, the L ₃ is of course is shorter than L _2. Further, the second exhaust outlet pipe 18 is formed to have a smaller diameter than the first exhaust outlet pipe 12, the communication pipe 16 is formed to have substantially the same diameter as the first exhaust outlet pipe 12, and the bypass pipe 19 has a smaller diameter than the communication pipe 16. Is formed.

Next, the operation of the first embodiment will be described. In a state where the outer end of the exhaust inlet pipe 9 is communicated with the exhaust pipe of the engine, the engine is stopped and a low rotation range (0 to 15) is set.
At 00 rpm), the valve 13a of the first opening / closing means 13 and the valve 17a of the second opening / closing means 17 are both in a closed state as shown in FIG. Therefore, the exhaust gas in the low rotational speed range of the engine is discharged from the exhaust inlet pipe 9 → the second small hole 11 → the second chamber 7 → the bypass pipe 19 → the first chamber 6 → the second exhaust outlet pipe 18 → the junction A → the 1 The exhaust gas is discharged through the path of the exhaust outlet pipe 12.

At this time, the second exhaust outlet pipe 18 is formed to have a small diameter, but since the engine is running at a low speed, the back pressure is an allowable back pressure. Also, the second exhaust outlet pipe 18 has a smaller diameter than the first exhaust outlet pipe 12 and
Longer than the length L ₃ to the exhaust inlet end of the first exhaust outlet pipe 12 from the so-called long-tail effect it can take enable low-frequency noise at a low rotation. Further, the third chamber 8 acts as a resonance chamber, and the second chamber 7 and the first
The chambers 6 are both silenced by acting as expansion chambers. In this way, sufficient silencing can be achieved.

Next, in the middle rotation range of the engine (1500-2
At 500 rpm), the valve 13a of the first opening / closing means 13 opens as shown in FIG. The valve element 17a of the second opening / closing means 17 remains in the closed state. Therefore, the exhaust gas in the middle rotation range mainly comes from the exhaust inlet pipe 9 → the second small hole 11
The second chamber 7 → the bypass pipe 19 → the first chamber 6 → the first opening / closing means 13 → the first exhaust outlet pipe 12 is discharged.

At this time, since the first opening / closing means 13 and the first exhaust outlet pipe 12 are larger in diameter than the second exhaust outlet pipe 18, the back pressure is prevented from increasing. Further, the third chamber 8 acts as a resonance chamber, and the second chamber 7 and the first chamber 6 both act as expansion chambers to mute the sound.

Next, in the high engine speed range (2500 rpm)
m or more), the valve 13a of the first opening / closing means 13 and the valve 17a of the second opening / closing means 17 both open as shown in FIG. Therefore, the exhaust gas in the high rotation region is mainly discharged from the exhaust inlet pipe 9 → second small hole 11 → second chamber 7 → communication pipe 16 → first chamber 6 → first opening / closing means 13 → first exhaust outlet pipe 12. It is discharged through the route.

At this time, the communication pipe 16 is connected to the bypass pipe 1
Since the diameter is larger than 9, the back pressure is prevented from increasing. The third chamber 8 acts as a resonance chamber, and the second chamber 7
The first chamber 6 and the first chamber 6 both act as expansion chambers and are silenced.

As described above, sufficient noise reduction and reduction of the back pressure according to each rotation can be achieved in the entire rotation range of the engine. Also, as in the above embodiment, preventing by setting the overall length L ₁ of the second exhaust outlet pipe 18 shorter than the first exhaust outlet pipe 12, the noise due columnar resonance at medium speed region or generated it can.

Further, by making the entire length L ₁ of the second exhaust outlet pipe 18 substantially equal to that of the first exhaust outlet pipe 12, the exhaust exhaust pipes 18 and 12 have a sufficient air-conditioning effect at low rotation. This is effective because the column resonance frequency can be set to the highest value.

FIG. 7 is a characteristic diagram showing the relationship between the rotational state of the engine and the sound pressure level and the back pressure. The characteristic shown by the dotted line L in FIG. 7 is such that both valve bodies 13a are closed as shown in FIG. The characteristic with respect to the rotation speed of the engine when fixed is shown. The characteristic indicated by the one-dot chain line M in FIG. 7 is such that the first valve body 13a is fixed in the open state and the second valve body 17a as shown in FIG. Shows the characteristics with respect to the engine speed when is fixed in the closed state,
The thin solid line H in FIG. 7 indicates that the two valve bodies 13a, 13
7 shows the characteristics with respect to the engine speed when 7a is fixed in the open state.

In consideration of the above characteristics, the two valve bodies 13 are adjusted so that the sound pressure level and the back pressure become the characteristics indicated by the thick solid line X in FIG.
By setting the urging force of the coil springs 13f, 17f of the a, 17a, it is possible to sufficiently reduce noise and reduce the back pressure in the entire rotation range.

FIG. 8 shows a second embodiment. In the second embodiment, the communication pipe 16 in the first embodiment is a communication pipe 16a that penetrates through the second chamber 7 and opens to the first chamber 6 and the third chamber 8, and the communication pipe 16a is provided on the first chamber 6 side. A first opening / closing means 17 similar to the above is provided. Since other structures are the same as those of the first embodiment, the same portions are denoted by the same reference numerals and the description thereof will be omitted.

In the second embodiment, the second opening / closing means 1
In the low and middle engine speed range where the valve element 17a of the valve 7 is closed, the third
The chamber 8 becomes a low-frequency resonance chamber, and the third chamber 8 is changed to an expansion chamber in the high engine speed range where the valve element 17a opens. By changing the third chamber 8 to an expansion chamber, the sound reduction due to expansion in the high engine speed range increases. Since the resonance chamber is used to muffle low frequencies, a low-frequency resonance chamber is unnecessary in a high rotation range.

It should be noted that the first opening / closing means 13 and the second opening / closing means 17 in each of the above-described embodiments are controlled by a valve element operating means using an actuator such as a solenoid valve and the valve element operating means by detecting the number of revolutions of the engine. A control means is provided to control the two valve bodies 13a, 17a based on the low, medium, and high engine speeds.
May be controlled to open and close as described above, whereby the same operation and effect as described above can be exerted.

However, as in the first embodiment, both valve elements 1
By controlling the opening and closing of the valves 3a and 17a by the pressure of the exhaust gas in the chamber 6, the valve operating means and control means are not required, and the muffler can be made compact and inexpensive.

Further, since the second exhaust outlet pipe 18 is formed shorter than the conventional second exhaust outlet pipe 114, the second exhaust outlet pipe 18 is provided with a silencer as shown in FIGS. It is sufficient to make a U-turn only on the front side wall 2 side of
The silencer can be made more compact as compared with the conventional case where the silencer is provided along the side wall of the outer cylinder of the silencer.

[0046]

As described above, according to the first aspect of the present invention, the noise reduction performance is enhanced in the low engine speed range, the back pressure is reduced in the middle engine speed range, and the back pressure is reduced in the high engine speed range. The back pressure can be further reduced, and the relationship between the muffling and the back pressure can be controlled as desired over the entire region.

According to the second aspect of the present invention, even if the above-described second exhaust outlet pipe is provided, the abnormal noise due to air column resonance in the second exhaust outlet pipe in a region equal to or higher than the middle rotation range of the engine. Can be prevented from occurring.

According to the third aspect of the invention, it is possible to further increase the silencing volume in a high engine speed range. According to the fourth aspect of the present invention, the opening and closing of the valve body of the opening and closing means can be performed without the need for the valve body operating means and the control means, as compared with the method of detecting and controlling the rotation amount of the engine, The silencer can be reduced in size and cost.

According to the fifth aspect of the present invention, both the opening and closing means can be formed of the same part, and the manufacturing cost can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a side view of the first opening / closing means shown in FIG.

FIG. 3 is a side view of the second opening / closing means shown in FIG. 1;

FIG. 4 is a diagram showing a state of an engine in a low rotation range in the silencer of the embodiment of FIG. 1;

FIG. 5 is a diagram showing a state of a middle rotation region of the engine in the silencer of the embodiment of FIG. 1;

FIG. 6 is a diagram showing a state of the engine in a high rotation range in the silencer of the embodiment of FIG. 1;

FIG. 7 is a characteristic diagram showing a relationship between a sound pressure level and a back pressure with respect to a rotation range of an engine in the silencer shown in FIG.

FIG. 8 is a sectional view showing a muffler according to a second embodiment of the present invention.

FIG. 9 is a sectional view showing a conventional silencer.

[Explanation of symbols]

6, 7, 8 chamber 9 exhaust inlet pipe 12 first exhaust outlet pipe 13 first opening / closing means 13a, 17a valve body 13f coil spring 16, 16a communication pipe 17 second opening / closing means 17f coil spring 18 ... second exhaust outlet pipe 19 ... bypass pipe

Continuation of the front page (56) References JP-A-63-266111 (JP, A) JP-A-60-216016 (JP, A) JP-A 2-13123 (JP, U) JP-A 2-18265 (JP , U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F01N 1/08

Claims (5)

(57) [Claims] 1. A Rutotomoni upstream comprises a first closing means
And opening into the muffler, the first exhaust outlet pipe downstream open to the outside silencer, which has a length suitable for silencing the low rotational speed range of the small diameter a and the engine than the first exhaust outlet pipe
A second exhaust outlet pipe having one end opened into the muffler, and the other end of the second exhaust outlet pipe being joined downstream of the first opening / closing means; a communicating pipe and the bypass pipe communicating the upstream side of the chamber, the second opening and closing means for opening and closing the communication pipe is provided, the bypass pipe is set smaller in diameter than the communicating pipe, the at low revs
Both opening and closing means are both closed, and the first opening and closing
A muffler characterized by opening a step and further opening a second opening / closing means in a high rotation range . 2. The muffler according to claim 1, wherein the total length of the second exhaust outlet pipe is set shorter than the total length of the first exhaust outlet pipe. 3. The muffler according to claim 1, wherein the exhaust inlet of the communication pipe is opened to a chamber that becomes a resonance chamber when the second opening / closing means is in a closed state. 4. The muffler according to claim 1, wherein the first opening / closing means and the second opening / closing means are operated to open by the exhaust gas pressure in the chambers of the respective pipes where the exhaust inlets open. 5. A butterfly type valve element wherein the first opening / closing means and the second opening / closing means are respectively opened by exhaust gas pressure,
5. The muffler according to claim 4, wherein said muffler comprises a coil spring for urging said valve body in a closing direction.