JP6528827B2 - Engine exhaust silencer - Google Patents

Description

  The present invention relates to an exhaust silencer of an engine.

  With regard to the exhaust silencer of an engine, Patent Document 1 provides a catalyst in each of two exhaust pipes extending from the engine, provides a muffler in the downstream part of each exhaust pipe, and provides a control valve in one of the exhaust pipes. It is described. By changing the output characteristic of the engine and the muffling characteristic of the exhaust system by controlling the opening and closing of the control valve according to the engine speed, by closing one exhaust pipe regardless of the engine speed during warm-up operation of the engine, This is to promote the warm-up of the engine by suppressing the escape of exhaust heat energy.

The microfilm of JP-A-2-86942 (JP-A-4-44446)

  During cold start of the engine, it is common practice to increase the fuel injection amount of the engine and to delay the ignition timing to raise the exhaust temperature in order to rapidly warm up the exhaust purification device (catalyst). The so-called afterburning of fuel is intended to raise the exhaust temperature. At the time of rapid warm-up of the exhaust gas control system, the engine speed is increased, and the amount of work on the piston is reduced because of the afterburning, and the combustion noise is increased. As a result, exhaust noise increases. Since this rapid warm-up is usually performed with the car stopped, it is required to suppress exhaust noise as much as possible.

  On the other hand, conventionally, the exhaust silencer of an engine is designed from the viewpoint of reducing exhaust noise as much as possible within the range where the engine output is not excessively dropped, assuming that the vehicle travels in the city area. Therefore, in the conventional exhaust silencer, there is a limit to the reduction of the exhaust noise at the time of the rapid warm-up.

  That is, it is conceivable to enhance the muffling effect of the exhaust silencer in order to obtain the quietness necessary at the time of rapid warm-up of the exhaust gas purification device, but enhancing the exhaust muffling property leads to an increase in exhaust resistance. Therefore, in order to obtain the quietness at the time of the rapid warm-up, the engine is operated with a large exhaust resistance even after the rapid warm-up, and the output performance of the engine is sacrificed.

  In Patent Document 1 described above, one exhaust pipe is closed to warm up the engine itself and the exhaust resistance is increased, and not for rapid warm-up of the exhaust gas purification device. In addition, since the muffler provided in the exhaust pipe is not used by closing one exhaust pipe, the exhaust noise is not necessarily reduced.

  An object of the present invention is to improve quietness during rapid warming-up of an exhaust gas purification device without sacrificing engine output.

  In order to solve the above-mentioned subject, the present invention provided the exhaust silencer which reduces the exhaust noise at the time of rapid warming up of the catalyst.

The exhaust silencer of the engine disclosed herein is provided on the downstream side of the exhaust flow rather than the exhaust purification device in the exhaust passage of the engine ,
A first exhaust path that reduces exhaust noise;
A second exhaust path having a larger air flow resistance than the first exhaust path and a high exhaust muffling property;
An exhaust muffler comprising: a third exhaust path having a lower ventilation resistance than the first exhaust path ;
A silencer housing in which an expansion chamber and a resonance chamber are defined by a partition wall;
A porous expansion type silencer comprising: the expansion chamber and an inlet pipe for introducing the exhaust gas of the engine into the expansion chamber, the inlet pipe being provided with a porous portion having a large number of holes for exhaust gas introduction;
A first outlet pipe for discharging the exhaust gas from the expansion chamber;
And a second outlet pipe, which has a smaller diameter than the first outlet pipe, and which discharges the exhaust gas from the expansion chamber,
The inlet pipe includes a porous pipe portion having the porous portion, and the downstream end in the exhaust flow direction of the porous pipe portion opens to the resonance chamber,
Furthermore, it includes a pass-through pipe that branches from the upstream side of the porous pipe portion in the exhaust flow direction of the inlet pipe and passes the expansion chamber to discharge the exhaust gas out of the silencer housing.
The first outlet pipe is an inner duct portion in which the upstream portion in the exhaust flow direction is inserted into the expansion chamber, and the downstream portion of the first outlet pipe in the exhaust flow direction protrudes from the silencer housing to form a first tail pipe Configure
The second outlet pipe is an inner duct portion in which the upstream portion in the exhaust flow direction is inserted into the expansion chamber, and the downstream end of the second outlet pipe is connected to a second tail pipe projecting from the silencer housing
The first exhaust path is formed by the porous expanded muffler and the first outlet pipe,
The second exhaust path is formed by the porous expanded silencer and the second outlet pipe,
The third exhaust path is formed by the pass-through pipe branched from the inlet pipe, and a downstream portion of the pass-through pipe, which protrudes from the silencer housing in the exhaust flow direction, constitutes the second tail pipe. ,
A control valve capable of closing the first exhaust path;
A control valve capable of closing the third exhaust path;
During engine operation to rapidly warm up the exhaust purification apparatus, as the exhaust of the engine passes through a lot of the second exhaust path than the first exhaust path, and controls the opening of the first exhaust path by the control valve And controlling the opening degree of the third exhaust path by the control valve such that the exhaust gas of the engine passes through the third exhaust path in a high rotation operation area not including the operation of rapidly warming up the exhaust gas purification device of the engine And an apparatus.

  At the time of rapid warm-up of the exhaust purification system, the engine is operated so that the exhaust temperature becomes high, so the combustion noise becomes large. On the other hand, in the exhaust silencer, since the exhaust gas passes through the second exhaust path having a high exhaust muffling property at the time of the rapid warm-up, it is advantageous for securing the quietness. Since the exhaust can pass through the relatively low first exhaust path of the ventilation resistance at the time of the rapid warm-up, the back pressure of the engine becomes excessively high, that is, the engine output during the normal running of the vehicle Can be avoided at the expense of

Further, in the high-revolution operating range of the engine, the exhaust gas passes through the third exhaust path having a low ventilation resistance, so the engine back pressure is reduced, which is advantageous for securing the engine output. In addition, since the third exhaust path has a smaller ventilation resistance than the first exhaust path, it is possible to create an exhaust sound in which the engine sound is emphasized.

Further, since the second exhaust path shares the porous expanded silencer with the first exhaust path, it can be configured simply by connecting a small-diameter second outlet pipe to the silencer, and the device is large in size. The exhaust noise during the warm-up operation of the exhaust purification device can be effectively reduced while avoiding That is, during warm-up operation of the exhaust purification device, silence is achieved by the muffling effect of the extended silencer, the exhaust gas led to the small-diameter second outlet pipe, and the muffling effect of large ventilation resistance and large area ratio. You can get it.

Further, in the first exhaust path, the sound is reduced by the interference effect of the muffling by the expansion type silencer and the sound wave by the inner duct of the first outlet pipe. In addition, since the downstream end of the perforated pipe is opened to the resonance chamber, the sound of the specific frequency can be efficiently reduced.

  Even in the second exhaust path, the noise is reduced by the interference effect of the muffle by the expansion type silencer and the sound wave by the inner duct of the second outlet pipe, but the small diameter of the second outlet pipe warms up the exhaust purification system. The reduction effect of the sound at the time of driving becomes large.

  Since the pass-through pipe forming the third exhaust path is branched from the above-mentioned inlet pipe and passes through the silencer housing, most of the exhaust gas is discharged by the flow-through pipe by dynamic pressure without entering the expansion chamber in the high engine speed operation region The engine sound becomes an emphasized exhaust sound.

Then, the second outlet pipe is connected to the expansion chamber forming the first exhaust path to form a second exhaust path, and the passage pipe is branched from the inlet pipe forming the first exhaust path to form a third exhaust path Thus, the first to third exhaust paths can be integrated into one silencer housing , which is advantageous for the compactness of the entire silencer.

According to the present invention, e without the engine output to sacrifice, Ri preferably Na in increasing the quietness during rapid warm-up of the exhaust purification device further advantageously ing the compactness of the entire silencer.

The perspective view showing the exhaust system of the engine of the car concerning an embodiment. The perspective view which shows the silencer housing which concerns on embodiment by an imaginary line, and shows the exhaust silencer of an engine. The block diagram of the exhaust route of the same exhaust silencer and a control system. The block diagram of the exhaust route of the exhaust silencer of the engine which concerns on reference form 1. FIG. FIG. 8 is a configuration diagram of an exhaust passage of an exhaust silencer of an engine according to a reference embodiment 2 ; The block diagram of the exhaust route of the exhaust silencer of the engine which concerns on reference form 3. FIG.

  Hereinafter, an embodiment for carrying out the present invention will be described based on the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its applications or its uses.

Embodiment
In the exhaust system of the automobile shown in FIG. 1, 1 is an exhaust gas purification device (catalyst) provided in a direct coupling pipe 2 connected to an exhaust manifold of the engine, and 3 is connected to the exhaust flow direction downstream end of the exhaust gas purification device 1 An exhaust pipe extending to the rear of the automobile under the floor of the automobile, 4 is an exhaust silencer provided at the rear end of the exhaust pipe 3, 5 and 6 project from both sides of the silencer housing 7 of the exhaust silencer 4 and directed to the rear of the automobile First and second tail pipes.

As shown in FIGS. 2 and 3, the exhaust silencer 4 includes one silencer housing 7. The silencer housing 7 is horizontally long, and the inside thereof is partitioned by the partition wall 11 into an extension chamber 12 and a resonance chamber 13 which are aligned in the left and right direction. The expansion chamber 12 has a larger volume than the resonance chamber 13. The exhaust pipe 3 is connected to an inlet pipe 14 projecting forward from the front wall 7 a (the front wall of the expansion chamber 12) of the silencer housing 7. The volumes of the expansion chamber 12 and the resonance chamber 13 are adjusted in size according to the frequency to be muffled.

  The inlet pipe 14 has a base portion extending toward the rear of the vehicle inside the expansion chamber 12 and has a porous pipe portion 15 extending laterally from the base portion inside the expansion chamber 12. The porous pipe portion 15 is provided with a porous portion 15 a having a large number of holes opened to the expansion chamber 12. The inlet pipe 14 and the expansion chamber 12 constitute a porous expansion type silencer. The perforated pipe portion 15 penetrates the partition wall 11, and the downstream end 15 b of the perforated pipe portion 15 in the exhaust flow direction is opened to the resonance chamber 13.

  Thus, a bypass pipe 16 is branched from the base of the inlet pipe 14 (the upstream end side of the porous pipe portion 15 in the exhaust flow direction) to let the exhaust gas pass through the expansion chamber 12 without flowing it out into the expansion chamber 12 doing. The pass-through tube 16 extends in the extending direction of the base of the inlet tube 14 and curves laterally, protrudes laterally from one side wall 7 b of the silencer housing 7 through the resonance chamber 13, and further curves backward. ing. A downstream portion in the exhaust gas flow direction projecting from the silencer housing 7 of the bypass pipe 16 constitutes a second tail pipe 6.

The first outlet pipe 21 and the second outlet pipe 22 are connected in parallel to the expansion chamber 12. The first outlet pipe 21 penetrates the other side wall 7 c of the silencer housing 7. The upstream portion 21 a in the exhaust flow direction of the first outlet pipe 21 is an inner duct portion inserted into the expansion chamber 12. The downstream portion in the exhaust flow direction of the first outlet pipe 21 protrudes laterally from the other side wall 7 c of the silencer housing 7 and is further curved backward to constitute a first tail pipe 5.

The upstream portion 22 a in the exhaust flow direction of the second outlet pipe 22 is an inner duct portion which penetrates the resonance chamber 13 and is inserted into the expansion chamber 12. The downstream portion in the exhaust flow direction of the second outlet pipe 22 protrudes laterally from the one side wall 7 b of the silencer housing 7, is curved backward, and is connected to the second tail pipe 6.

  The pipe diameter (inner diameter) of the second outlet pipe 22 is smaller than the pipe diameter of the first outlet pipe 21.

  A first control valve 23 capable of closing the first outlet pipe 21 is provided at the downstream portion of the first outlet pipe 21 projecting from the silencer housing 7. A second control valve 24 capable of closing the through hole 16 is provided in the downstream portion of the through pipe 16 which protrudes from the silencer housing 7. The second outlet pipe 22 is connected downstream of the second control valve 24 of the bypass pipe 16 in the exhaust flow direction.

  The operation of the first and second control valves 23 and 24 is controlled by the control device 25 using a microcomputer according to the operating state of the engine and the like. For the control, the control device 25 receives information on the engine rotational speed detected by a sensor or the like, the fuel injection amount of the engine, the intake air amount of the engine, the outside air temperature, and the like.

  That is, in the first control valve 23, the first outlet pipe 21 is fully closed only during engine operation for rapidly warming up the exhaust gas purification device 1, and the first outlet pipe 21 is fully open during other engine operations. The controller 25 controls the operation.

  Whether the rapid warm-up is necessary or not is whether the temperature of the exhaust gas purification device 1 estimated based on information on the engine operating condition etc. is below a predetermined value (temperature at which the catalyst shows a predetermined activity, for example 200 ° C.) It is judged by. In addition, the temperature of the exhaust gas purification device 1 can be directly detected by a sensor to determine whether or not the rapid warm-up is necessary. The rapid warm-up is performed by increasing the fuel injection amount of the engine and retarding the ignition timing to raise the exhaust gas temperature.

  The operation of the second control valve 24 is controlled by the control device 25 so that the pass-through pipe 16 is fully opened only in the high rotation operation range (for example, 4000 rpm or more or 5000 rpm or more) of the engine.

  Therefore, when the exhaust gas purification device 1 is not rapidly warmed up in the low to medium rotation operating range of the engine, the first control valve 23 is in the open state, and the second control valve 24 is in the closed state. Thus, at this time, the exhaust gas is discharged from the base of the inlet pipe 14 through the porous pipe portion 15, the expansion chamber 12 and the first outlet pipe 21.

  The inlet pipe 14, the expansion chamber 12 and the first outlet pipe 21 reduce exhaust noise in the low to medium engine speed operating range (except when the exhaust gas purification device 1 is rapidly warmed up). The first exhaust path is configured.

  In the first exhaust path, the exhaust sound is reduced by the porous expansion silencer formed by the inlet pipe 14 and the expansion chamber 12, and the exhaust sound is reduced by the interference effect of the sound waves by the inner duct of the first outlet pipe 21. In addition, since the downstream end of the porous pipe portion 15 is open to the resonance chamber 13, the specific frequency component of the exhaust sound can be efficiently reduced.

  During engine operation for rapidly warming up the exhaust gas purification device 1, the first control valve 23 is closed. In addition, at the time of this engine operation, although the engine speed is increased, it is not increased up to the high speed operation region. Therefore, the second control valve 24 is in the closed state. Thus, at this time, the exhaust gas is discharged from the inlet pipe 14 through the expansion chamber 12 and the second outlet pipe 22.

  The inlet pipe 14, the expansion chamber 12 and the second outlet pipe 22 constitute a second exhaust path which reduces exhaust noise during engine operation for rapidly warming up the exhaust purification device 1.

  In this second exhaust path, as in the first exhaust path, the exhaust noise is reduced by the porous expanded silencer by the inlet pipe 14 and the expansion chamber 12, but unlike the first exhaust path, the exhaust is the expansion chamber 12 Are discharged through the second outlet pipe 22. Since the second outlet pipe 22 is smaller in diameter than the first outlet pipe 21 and has higher ventilation resistance, the exhaust muffling property is higher than that of the first exhaust path.

  Therefore, at the time of the engine operation which warms up the exhaust gas purification device 1 rapidly, the exhaust noise is effectively reduced by the second exhaust path, which is advantageous for ensuring quietness more than the first exhaust path. With regard to the reduction of the exhaust noise at the time of rapid warm-up of the exhaust gas purification device 1, the adjustment of the pipe diameter and the length of the second outlet pipe 22 can be tuned to increase the sound reduction effect at a desired frequency. .

  As described above, since the exhaust noise at the time of rapid warming up of the exhaust gas purification device 1 is reduced in the second exhaust path, it is not necessary to configure the first exhaust path in consideration of the exhaust noise at the time of rapid warming up. That is, in the first exhaust path, it is sufficient if a muffling effect can be obtained to the extent required when traveling a car in the city area, throttling the exhaust at the porous portion 15a of the inlet pipe 14 at the expense of engine output. It is not necessary to make the diameter of the first outlet pipe 21 excessively large or to be excessively small.

  When the engine is operating in the high revolution operating region, the second control valve 24 of the bypass pipe 16 is opened. Therefore, at this time, much of the exhaust gas is discharged from the inlet pipe 14 through the bypass pipe 16 by dynamic pressure (kinetic energy) without entering the expansion chamber 12. The inlet pipe 14 and the bypass pipe 16 constitute a third exhaust path for exhausting the exhaust gas in the high rotation operation region of the engine.

  In this third exhaust path, the exhaust gas is discharged from the inlet pipe 14 through the bypass pipe 16 without passing through the expansion chamber 12, so the air flow resistance is smaller than that of the first exhaust path. Therefore, there is not much reduction of the exhaust noise, and the engine sound becomes an enhanced exhaust noise. The fact that the ventilation resistance of the third exhaust path is small means that the back pressure of the engine is small, which is advantageous for improving the output of the engine.

  In addition, since the first control valve 23 is also open in the high-revolution operating range of the engine, the exhaust gas entering the expansion chamber 12 from the inlet pipe 14 mainly by static pressure is discharged through the first outlet pipe 21. The exhaust can also pass through the second outlet pipe 22. Thus, the exhaust can pass through the first exhaust path and the second exhaust path, so the back pressure of the engine is further reduced, which is advantageous for improving the engine output.

  In the above embodiment, although the bypass pipe 16 is branched from the inlet pipe 14 in the expansion chamber 12, the bypass pipe 16 is branched from the inlet pipe 14 in front of the expansion chamber 12 (outside of the silencer housing 7). The tube 16 can also be prevented from passing through the silencer housing 7.

< Reference Form 1 >
The present embodiment is shown in FIG. In the embodiment , the through pipe 16 is branched from the inlet pipe 14. However, in the present embodiment , a single porous through pipe 31 penetrating the expansion chamber 12 is provided, and the porous through pipe 31 is described in the embodiment . The exhaust pipe 3 is connected. The porous through pipe 31 includes a porous portion 31 a having a large number of holes opened to the expansion chamber 12, and constitutes an inlet pipe for introducing the exhaust gas into the expansion chamber 12 and bypassing the expansion chamber 12. A pass-through pipe is provided to discharge the exhaust gas. The porous portion 31a of the porous through tube 31 and the expansion chamber 12 constitute a porous expansion type silencer.

Further, as in the embodiment , the first outlet pipe 21 and the second outlet pipe 22 whose pipe diameter is smaller than that of the first outlet pipe 21 are connected to the expansion chamber 12. Then, the first outlet pipe 21 is provided with a first control valve 23 which is closed when the exhaust gas purification device 1 is rapidly warmed up, and the porous through pipe 31 is provided with a second control valve 24 which is opened in an engine high rotation operation region. It is done.

  Therefore, when the exhaust gas purification device 1 is not rapidly warmed up in the low to medium rotation operating range of the engine, the first control valve 23 is opened and the second control valve 24 is closed. It enters the expansion chamber 12 from the porous portion 31 a 31 and is discharged from the expansion chamber 12 through the first outlet pipe 21. The porous through pipe 31, the expansion chamber 12 and the first outlet pipe 21 reduce exhaust noise in the low to medium rotation operating region of the engine (except when the exhaust gas purification device 1 is rapidly warmed up). The first exhaust path is configured.

  Since the first control valve 23 is closed at the time of engine operation for rapidly warming up the exhaust gas purification device 1, the exhaust entering the expansion chamber 12 from the porous portion 31 a of the porous through pipe 31 is the second outlet pipe from the expansion chamber 12. Ejected through 22 The porous through pipe 31, the expansion chamber 12 and the second outlet pipe 21 constitute a second exhaust path which reduces exhaust noise at the time of rapid warming up of the exhaust purification device 1.

  Since the second outlet pipe 22 is smaller in diameter than the first outlet pipe 21 and has high ventilation resistance, the exhaust muffling property is higher than that of the first exhaust path. That is, exhaust noise during engine operation for rapidly warming up the exhaust purification device 1 is effectively reduced by the second exhaust path.

  When the engine is in the operation state of the high rotation operation range, the second control valve 24 of the porous through pipe 31 is opened, so most of the exhaust gas passes through the porous through pipe 31 by dynamic pressure without entering the expansion chamber 12 Discharged. The porous through pipe 31 constitutes a third exhaust path for exhausting the exhaust gas in the high rotation operating region of the engine.

In this third exhaust path, the exhaust gas is discharged by bypassing the expansion chamber 12 by the porous through pipe 31, so the air flow resistance is smaller than that of the first exhaust path. Therefore, as in the embodiment , there is not much reduction of the exhaust noise, the engine sound becomes an enhanced exhaust noise, and it is also advantageous for improving the output of the engine.

Further, in the high-revolution operating range of the engine, the first control valve 23 is also open, so that the exhaust gas is discharged through the porous portion 31a, the expansion chamber 12 and the first outlet pipe 21; Discharge from the outlet pipe 22 is the same as in the embodiment .

< Reference Form 2 >
This preferred embodiment, as shown in FIG. 5, as in the embodiment, is obtained by connecting a second outlet pipe 22 on the downstream side of the exhaust gas flow direction than the second control valve 24 in perforated through tube 31, the other The configuration is the same as in the first embodiment .

< Reference Form 3 >
In the present embodiment , as shown in FIG. 6, the exhaust pipe 3 is branched into two branch pipes 3a and 3b, and the mufflers of the second embodiment are provided to the branch pipes 3a and 3b.

Although not shown, each branch pipe 3a, the noise suppressor of the embodiment 3b, or may be provided silencer of Reference Embodiment 1.

<Others>
In the embodiment and the reference embodiment , the first control valve 23 and the second control valve 24 are replaced by on / off valves in which the valve body switches to two positions of full opening and full closing, depending on the engine operating condition. It is also possible to employ an opening control valve capable of adjusting the opening of the valve in a stepwise or continuous manner. Thus, the muffling characteristic and the engine output characteristic of the muffling apparatus can be linearly adjusted in accordance with the engine operating condition.

  In addition, a sound absorbing material may be disposed in the expansion chamber 12 for converting sound energy into heat energy to obtain a sound reduction effect, and the high frequency sound may be reduced by the viscosity and friction of the sound absorbing material. For example, the inner wall surface of the expansion chamber 12 can be covered with a sound absorbing material. Alternatively, the inner duct portion (upstream portion) 21a of the first outlet pipe 21 is provided with a porous portion in which a large number of holes are opened in the pipe wall, and the outer periphery of the pipe wall having this porous portion is covered with a sound absorbing material of glass wool Alternatively, a double pipe type silencer may be provided in which the sound absorbing material layer is covered with an outer pipe. In that case, the upstream end of the first outlet pipe 21 is opened without being closed. The upstream end of the first outlet pipe 21 can also be closed.

Reference Signs List 1 exhaust gas purification device 3 exhaust pipe 4 exhaust silencer 5 first tail pipe 6 second tail pipe 7 silencer housing 11 partition wall 12 extension chamber (constituting first and second exhaust paths)
13 resonance chamber 14 inlet pipe (constituting first to third exhaust paths)
15 Perforated tube (constituting first exhaust path)
15a Perforated section 16 straight through pipe (constituting the third exhaust path)
21 first outlet pipe (constituting the first exhaust path)
22 second outlet pipe (constitutes the second exhaust path)
23 first control valve 24 second control valve 25 controller

Claims (1)

It is provided on the downstream side of the exhaust flow rather than the exhaust purification device in the exhaust passage of the engine ,
A first exhaust path that reduces exhaust noise;
A second exhaust path having a larger air flow resistance than the first exhaust path and a high exhaust muffling property;
An exhaust muffler comprising: a third exhaust path having a lower ventilation resistance than the first exhaust path ;
A silencer housing in which an expansion chamber and a resonance chamber are defined by a partition wall;
A porous expansion type silencer comprising: the expansion chamber and an inlet pipe for introducing the exhaust gas of the engine into the expansion chamber, the inlet pipe being provided with a porous portion having a large number of holes for exhaust gas introduction;
A first outlet pipe for discharging the exhaust gas from the expansion chamber;
And a second outlet pipe, which has a smaller diameter than the first outlet pipe, and which discharges the exhaust gas from the expansion chamber,
The inlet pipe includes a porous pipe portion having the porous portion, and the downstream end in the exhaust flow direction of the porous pipe portion opens to the resonance chamber,
Furthermore, it includes a pass-through pipe that branches from the upstream side of the porous pipe portion in the exhaust flow direction of the inlet pipe and passes the expansion chamber to discharge the exhaust gas out of the silencer housing.
The first outlet pipe is an inner duct portion in which the upstream portion in the exhaust flow direction is inserted into the expansion chamber, and the downstream portion of the first outlet pipe in the exhaust flow direction protrudes from the silencer housing to form a first tail pipe Configure
The second outlet pipe is an inner duct portion in which the upstream portion in the exhaust flow direction is inserted into the expansion chamber, and the downstream end of the second outlet pipe is connected to a second tail pipe projecting from the silencer housing
The first exhaust path is formed by the porous expanded muffler and the first outlet pipe,
The second exhaust path is formed by the porous expanded silencer and the second outlet pipe,
The third exhaust path is formed by the pass-through pipe branched from the inlet pipe, and a downstream portion of the pass-through pipe, which protrudes from the silencer housing in the exhaust flow direction, constitutes the second tail pipe. ,
A control valve capable of closing the first exhaust path;
A control valve capable of closing the third exhaust path;
During engine operation to rapidly warm up the exhaust purification apparatus, as the exhaust of the engine passes through a lot of the second exhaust path than the first exhaust path, and controls the opening of the first exhaust path by the control valve And controlling the opening degree of the third exhaust path by the control valve such that the exhaust gas of the engine passes through the third exhaust path in a high rotation operation area not including the operation of rapidly warming up the exhaust gas purification device of the engine An exhaust silencer of an engine, comprising: a device;

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