JP4655560B2 - Exhaust system silencer - Google Patents

Description

  The present invention relates to an exhaust system silencer for silencing exhaust sound of exhaust gas.

In Patent Document 1 below, a sealed hollow portion having a longitudinal direction in the vehicle front-rear direction is formed in a side guard provided on a side portion of a vehicle body, and a flexible tube is used as an exhaust pipe provided with an expansion type muffler. Thus, a technology has been disclosed in which the hollow portion is used as a resonance box by connecting them, thereby reducing exhaust noise.
Japanese Utility Model Publication No. 5-96418 Japanese Utility Model Publication No. 5-56514 Japanese Utility Model Publication No. 5-96416

  However, according to the above prior art, a sufficient silencing effect cannot be obtained because the silencing effect is in a specific frequency band corresponding to the length of the hollow tube used as the resonance box.

  An object of the present invention is to obtain an exhaust silencer capable of obtaining a sufficient silencing effect from a low load to a high load or from a low speed to a high speed.

The exhaust system silencer according to the first aspect of the present invention sets flow switching means capable of opening and closing at a predetermined position of an exhaust pipe connecting the engine and the muffler, and exhausts upstream of the flow switching means. Set the exhaust gas inlet of the heat exchanger for exhaust heat recovery that recovers exhaust heat by exchanging heat with gas, and set the exhaust gas outlet of the heat exchanger for exhaust heat recovery downstream of the flow path switching means The exhaust heat recovery heat exchanger is used as an exhaust gas silencer , and the exhaust heat recovery heat exchanger is provided integrally with the outer periphery of the exhaust pipe, and the exhaust The inside of the heat recovery heat exchanger is divided into a plurality of chambers, and the exhaust gas introduced from the exhaust gas inlet of the exhaust pipe passes through the plurality of chambers in order according to a predetermined order and is then exhausted. The exhaust gas discharged from the outlet The exhaust port is formed in the first chamber in the determined order and the exhaust gas discharge port is formed in the last chamber in the determined sequence, and the exhaust heat recovery heat exchanger is connected from the exhaust gas inlet. The length of the flow path to the exhaust gas discharge port that is passed through is set longer than the length of the pipe line from the exhaust gas introduction port to the exhaust gas discharge port in the exhaust pipe .

According to a second aspect of the present invention, there is provided an exhaust system silencer according to the first aspect of the present invention, wherein the exhaust gas discharge port is provided with a discharge port opening / closing means capable of opening and closing the exhaust gas discharge port. It is characterized by that.

According to a third aspect of the present invention, there is provided an exhaust silencer according to the present invention, wherein flow switching means that can be controlled to be opened and closed is set at a predetermined position of an exhaust pipe that connects the engine and the muffler, and the exhaust is disposed upstream of the flow switching means. Set the exhaust gas inlet of the heat exchanger for exhaust heat recovery that recovers exhaust heat by exchanging heat with gas, and set the exhaust gas outlet of the heat exchanger for exhaust heat recovery downstream of the flow path switching means Thus, the exhaust heat recovery heat exchanger is used as a means for silencing exhaust gas, and the exhaust gas discharge port is provided downstream of the exhaust gas discharge port and disconnected from the exhaust gas discharge port. It is characterized by being connected to a space having a large area .

Exhaust system muffler according to the present invention of claim 4 is the invention according to any one of claims 1 to 3, further wherein the flow path shifting unit is closed in the low load or low speed It is characterized in that it is opened at the time of medium / high load or medium / high speed.

  According to a fifth aspect of the present invention, there is provided an exhaust system silencer according to any one of the first to fourth aspects, wherein the exhaust heat recovery heat exchanger is set independently of the exhaust pipe. It is characterized by being connected to the exhaust pipe by piping.

According to the first aspect of the present invention, when the exhaust heat recovery heat exchanger is used as the noise reduction means, the flow path switching means is controlled to be opened and closed, and the exhaust gas passing through the exhaust pipe is exhausted heat recovery heat. Be guided to the exchange side. If it does in this way, exhaust gas will be guide | induced to the heat exchanger for exhaust heat recovery from the exhaust-gas inlet provided in the upstream of the flow-path switching means, and will be heat-exchanged by the said heat exchanger for exhaust heat recovery. Thereby, the exhaust heat of the exhaust gas is recovered, and the exhaust gas itself is cooled and lowered in temperature. When the exhaust gas is cooled, the gas flow rate (volume) decreases, so that a silencing effect corresponding to that is obtained. The exhaust gas that has achieved the silencing effect is discharged from an exhaust gas discharge port set on the downstream side of the flow path switching means, further silenced through the muffler, and then discharged outside the vehicle. In the present invention, as will be described later, the exhaust heat recovery heat exchanger is provided integrally with the outer periphery of the exhaust pipe, and the interior of the exhaust heat recovery heat exchanger is divided into a plurality of chambers. The exhaust gas introduced from the exhaust gas introduction port of the exhaust pipe passes through the plurality of chambers in order according to a predetermined order and is then discharged from the exhaust gas discharge port. The exhaust gas inlet is formed in the first chamber in the determined order, and the exhaust gas outlet is formed in the last chamber in the determined order.

Further, according to the present invention, the opening degree of the flow path switching means is adjusted (closed) at low load and low speed immediately after engine start so that the exhaust gas flows to the exhaust heat recovery heat exchanger side. . Thus, the exhaust gas is recovered and cooled by the heat exchange action of the exhaust heat recovery heat exchanger. For this reason, the flow rate (volume) of the exhaust gas is reduced. Therefore, the noise reduction effect of the exhaust gas at low load and low speed can be obtained.

On the other hand, at the time of medium / high load and medium / high speed, the opening degree of the flow path switching means is adjusted (opened) so that most of the exhaust gas flows directly to the muffler through the exhaust pipe. Here, in the present invention, the length of the flow path from the exhaust gas inlet to the exhaust gas outlet through the heat exchanger for exhaust heat recovery is defined as the length of the pipe from the exhaust gas inlet to the exhaust gas outlet in the exhaust pipe. Therefore, there is a phase difference between the exhaust pulsation (exhaust sound pressure) on the exhaust heat recovery heat exchanger side and the exhaust pulsation (exhaust sound pressure) on the exhaust pipe side. An effect is obtained.
In addition, according to the present invention, the heat exchanger for exhaust heat recovery is integrally provided on the outer peripheral portion of the exhaust pipe, so that the installation space can be reduced.
Further, according to the present invention, the interior of the heat exchanger for exhaust heat recovery is divided into a plurality of chambers, and the exhaust gas introduced from the exhaust gas inlet of the exhaust pipe is determined in a predetermined order. Therefore, the flow path length can be changed to an arbitrary length.

According to the second aspect of the present invention, the opening degree of the flow path switching means is adjusted (closed) at the time of low load immediately after engine startup and at low speed, and the exhaust gas is on the side of the heat exchanger for exhaust heat recovery. To flow to. At this time, the outlet opening / closing means is opened. Thus, the exhaust gas is recovered and cooled by the heat exchange action of the exhaust heat recovery heat exchanger. For this reason, the flow rate (volume) of the exhaust gas is reduced. Therefore, as in the first aspect of the invention, the effect of silencing exhaust gas at low load and low speed can be obtained.

  On the other hand, at the time of medium / high load and medium / high speed, the opening degree of the flow path switching means is adjusted (opened) so that most of the exhaust gas flows directly to the muffler through the exhaust pipe. At this time, the outlet opening / closing means is closed. As a result, the flow path on the exhaust heat recovery heat exchanger side from the exhaust gas inlet to the exhaust gas outlet becomes a resonance device (space) with a closed end on one side, and the exhaust sound of the frequency corresponding to the flow path length is muted. The In addition, by making the closing position of the exhaust gas discharge port by the discharge port opening / closing means variable, the frequency band that can be silenced is expanded.

According to the third aspect of the present invention, the opening degree of the flow path switching means is adjusted (closed) at the time of low load immediately after engine start and at low speed, and the exhaust gas is on the side of the heat exchanger for exhaust heat recovery. To flow to. Thus, the exhaust gas is recovered and cooled by the heat exchange action of the exhaust heat recovery heat exchanger. For this reason, the flow rate (volume) of the exhaust gas is reduced.

  Furthermore, in the present invention, the exhaust gas discharge port is connected to a space provided downstream of the exhaust gas discharge port and having a larger cross-sectional area than the exhaust gas discharge port. When sound is discharged, a silencing effect is obtained by an expansion effect.

  By these cooling action and expansion action, the effect of silencing exhaust gas at low load and low speed can be obtained.

  On the other hand, at the time of medium / high load and medium / high speed, the opening degree of the flow path switching means is adjusted (opened) so that most of the exhaust gas flows directly to the muffler through the exhaust pipe. Usually, since the cross-sectional area of the muffler is larger than the cross-sectional area of the exhaust pipe, when the exhaust gas is discharged from the exhaust pipe to the muffler, a silencing effect due to the expansion effect is obtained.

  Further, in the present invention, as described above, the exhaust gas discharge port is connected to a space provided downstream of the exhaust gas discharge port and having a larger cross-sectional area than the exhaust gas discharge port. Silence due to expansion effect can be obtained on the exit side.

  Therefore, the expansion effect is doubled at medium and high loads and at medium and high speeds, and a mute effect corresponding to the expansion effect is obtained.

  According to the fifth aspect of the present invention, the heat exchanger for exhaust heat recovery is set independently from the exhaust pipe, and is connected to the exhaust pipe by piping, so the exhaust heat recovery at an arbitrary position The heat exchanger can be used as a silencer.

As described above, the exhaust system silencer according to the first aspect of the present invention sets the flow path switching means that can be opened and closed at a predetermined position of the exhaust pipe connecting the engine and the muffler. An exhaust gas inlet of an exhaust heat recovery heat exchanger that recovers exhaust heat by exchanging heat with exhaust gas is set upstream of the means, and an exhaust heat recovery heat exchanger is installed downstream of the flow path switching means. By setting the exhaust gas discharge port, the exhaust heat recovery heat exchanger is used as an exhaust gas silencer , and the exhaust heat recovery heat exchanger is provided integrally with the outer peripheral portion of the exhaust pipe. In addition, the interior of the heat exchanger for exhaust heat recovery is divided into a plurality of chambers, and the exhaust gas introduced from the exhaust gas inlets of the exhaust pipes is sequentially passed through the plurality of chambers according to a predetermined order. Exhaust from exhaust gas outlet after passing The exhaust gas inlet is formed in the first chamber in the determined order, the exhaust gas outlet is formed in the last chamber in the determined order, and the exhaust heat is discharged from the exhaust gas inlet. The length of the flow path from the exhaust gas exhaust port through the recovery heat exchanger to the exhaust gas exhaust port is set to be longer than the length of the pipe from the exhaust gas introduction port to the exhaust gas exhaust port in the exhaust pipe. The exhaust gas can be cooled using the heat exchanger for recovery, and as a result, there is an excellent effect that a sufficient silencing effect can be obtained from a low load to a high load or from a low speed to a high speed.

The exhaust silencer according to the present invention as set forth in claim 1 is characterized in that the length of the flow path from the exhaust gas inlet to the exhaust gas outlet through the exhaust heat recovery heat exchanger is defined as the exhaust gas inlet in the exhaust pipe. Because it is set longer than the pipe length from the exhaust gas exhaust port to the exhaust gas exhaust port, the mutual effect of the noise reduction effect by cooling the exhaust gas and the phase difference between the exhaust air pulsation on the exhaust heat recovery heat exchanger side and the exhaust pipe side As a result, it has an excellent effect that a sufficient silencing effect can be obtained from a low load to a high load or from a low speed to a high speed.
Further, in the exhaust silencer according to the present invention of claim 1, since the heat exchanger for exhaust heat recovery is integrally provided on the outer peripheral portion of the exhaust pipe, installation space can be reduced. It has an excellent effect that it can be installed in many vehicle types.
In the exhaust silencer according to the present invention, the exhaust heat recovery heat exchanger is divided into a plurality of chambers, and the exhaust gas introduced from the exhaust gas inlet of the exhaust pipe is Since the plurality of chambers are arranged in order according to a predetermined order and then discharged from the exhaust gas discharge port, the flow path length can be changed to an arbitrary length, and as a result, the heat for exhaust heat recovery It has an excellent effect that the exchanger itself can be miniaturized.

An exhaust system muffler according to the present invention described in claim 2, in the invention according to the first aspect, since the exhaust gas outlet to the exhaust gas outlet provided with openable discharge opening and closing means, the cooling of the exhaust gases Both the silencing effect due to resonance and the silencing effect due to the resonant action of the closed end on one side are obtained, and as a result, it has an excellent effect that a sufficient silencing effect can be obtained from low load to high load or from low speed to high speed .

According to a third aspect of the present invention, there is provided an exhaust silencer according to the present invention, wherein flow switching means that can be controlled to be opened and closed is set at a predetermined position of an exhaust pipe that connects the engine and the muffler, and the exhaust is disposed upstream of the flow switching means. Set the exhaust gas inlet of the heat exchanger for exhaust heat recovery that recovers exhaust heat by exchanging heat with gas, and set the exhaust gas outlet of the heat exchanger for exhaust heat recovery downstream of the flow path switching means Thus, the exhaust heat recovery heat exchanger is used as a means for silencing the exhaust gas, and the exhaust gas discharge port is provided on the downstream side of the exhaust gas discharge port and has a cross-sectional area larger than that of the exhaust gas discharge port. Because it is connected to a large space , both the silencing effect due to the cooling effect of the exhaust gas and the silencing effect due to the expansion effect are obtained. As a result, it is sufficient from low load to high load or from low speed to high speed Mute effect It has an excellent effect that is.

  According to a fifth aspect of the present invention, there is provided an exhaust silencer according to any one of the first to fourth aspects, wherein the exhaust heat recovery heat exchanger is set independently of the exhaust pipe. Because it is connected to the exhaust pipe by piping, the exhaust heat recovery heat exchanger at any position can be used as a silencer, and as a result, there are multiple exhaust heat recovery heat exchangers Has an excellent effect that the exhaust heat recovery heat exchanger having the highest noise reduction effect can be selected.

[First Embodiment]
Hereinafter, a first embodiment of an exhaust system silencer according to the present invention will be described with reference to FIGS.

  FIG. 1 shows an overall configuration diagram of an exhaust heat recovery system 12 configured to include an exhaust system silencer 10 according to the present embodiment. FIG. 2 is an enlarged view of the exhaust system silencer 10 according to the main part of the exhaust heat recovery system 12.

  As shown in these drawings, the exhaust heat recovery system 12 includes an exhaust pipe 14 that constitutes a main part of an automobile exhaust system. One end portion (front end portion) of the exhaust pipe 14 is connected to the exhaust manifold of the engine 16, and the other end portion (rear end portion) of the exhaust pipe 14 is disposed under the floor at the rear end portion of the vehicle body. An underfloor catalyst 18 for purifying exhaust gas is disposed upstream of the exhaust pipe 14 (on the engine 16 side). A main muffler 20 for reducing the exhaust noise of the exhaust gas is disposed downstream of the exhaust pipe 14 (near the rear end).

  Between the underfloor catalyst 18 and the main muffler 20 in the exhaust pipe 14, an exhaust heat recovery heat exchanger 22 is connected as a silencer. In the present embodiment, the exhaust heat recovery heat exchanger 22 is an EGR cooler (EGR cooler as a base) that is a component of an exhaust gas recirculation device (EGR) that returns part of the exhaust gas to the intake system. Including heat exchangers that have been modified as appropriate. The exhaust heat recovery heat exchanger 22 and the exhaust pipe 14 are connected by a pipe line 24 (communication with each other via the pipe line 24). Connection portions of the exhaust pipe 14 to the pipe line 24 of the exhaust heat recovery heat exchanger 22 are each opened. The connection portion located on the upstream side of the exhaust pipe 14 is an exhaust gas introduction port 26, and the connection portion located on the downstream side of the exhaust pipe 14 is an exhaust gas discharge port 28.

  A heater hot water flow path 30 is connected to the exhaust heat recovery heat exchanger 22. A front heater core 32 is disposed between the engine 16 and the exhaust heat recovery heat exchanger 22 in the heater hot water flow path 30. Refrigerant (warm water) flows in the heater hot water flow path 30 in the direction of the arrow in FIG. 1. When the hot water passing through the engine 16 passes through the front heater core 32, heat is exchanged and used for heating. When the hot water lowered in temperature flows from the front heater core 32 through the exhaust heat recovery heat exchanger 22, heat is exchanged with the exhaust gas introduced into the exhaust heat recovery heat exchanger 22 to cool the exhaust gas. It has become.

  Further, a flow path switching valve 34 as a flow path switching means is set between the exhaust gas inlet 26 and the exhaust gas outlet 28 in the exhaust pipe 14. The flow path switching valve 34 is connected to a vacuum path 36 connected to the intake side of the engine 16. In the vacuum path 36, an actuator (negative pressure diaphragm) 38, a vacuum switching valve (VSV) 40, and a vacuum tank 42 which constitute a part of the exhaust gas recirculation device are disposed.

  The vacuum switching valve 40 is connected to the engine ECU 44 and its operation is controlled. That is, when an exhaust heat recovery instruction is issued from the engine ECU 44, the vacuum switching valve 40 is operated to operate the actuator 38. As a result, the open / closed state of the flow path switching valve 34 is switched by applying a negative pressure.

  Furthermore, in this embodiment, as shown in FIG. 2, the length (pipe length L <b> 2) of the pipe 24 of the heat exchanger 22 for exhaust heat recovery described above is from the exhaust gas inlet 26 in the exhaust pipe 14. It is set longer than the length to the exhaust gas discharge port 28 (pipeline length L1).

(Operation and effect of this embodiment)
Next, the operation and effect of this embodiment will be described.

  At the time of low load immediately after engine startup and at low speed, the flow path switching valve 34 is closed. Therefore, the exhaust gas flows into the pipe line 24 from the exhaust gas inlet 26 and is sent to the exhaust heat recovery heat exchanger 22. In the heat exchanger 22 for exhaust heat recovery, heat exchange is performed between the refrigerant (hot water) flowing through the heater hot water flow path 30 and the high-temperature exhaust gas, and exhaust heat is recovered and the exhaust gas itself is cooled. For this reason, the flow rate (volume) of the exhaust gas is reduced. Therefore, the noise reduction effect of the exhaust gas at low load and low speed can be obtained. After that, the exhaust gas is discharged from the exhaust gas discharge port 28 into the exhaust pipe 14 through the pipe line 24, and then sent to the main muffler 20 to be further silenced.

  On the other hand, the flow path switching valve 34 is opened during medium and high loads and during medium and high speeds. For this reason, most of the exhaust gas is sent directly to the main muffler 20 through the exhaust pipe 14 (note that some exhaust gas flows into the exhaust heat recovery heat exchanger 22 side).

  Here, in the present embodiment, the pipe length L2 from the exhaust gas inlet 26 to the exhaust gas outlet 28 via the exhaust heat recovery heat exchanger 22 is changed from the exhaust gas inlet 26 in the exhaust pipe 14 to the exhaust gas. The phase difference between the exhaust pulsation (exhaust sound) on the exhaust heat recovery heat exchanger 22 side and the exhaust pulsation (exhaust sound) on the exhaust pipe 14 side is set because it is set longer than the pipe line length L1 to the exhaust port 28. And a silencing effect is obtained by the interference action between the two.

  The frequency f2 of the exhaust sound on the exhaust heat recovery heat exchanger 22 side at this time is expressed by f2 = C / (2 × L2), and the frequency f1 of the exhaust sound on the exhaust pipe 14 side is f1 = C. / (2 × L1). However, C is a constant.

  Thereafter, the silenced exhaust gas is discharged from the exhaust gas discharge port 28 to the exhaust pipe 14 and then sent to the main muffler 20 for further noise reduction.

  As described above, according to the exhaust heat recovery system 12 including the exhaust system silencer 10 according to the present embodiment, a sufficient silencing effect can be obtained from a low load to a high load or from a low speed to a high speed. Accordingly, since the noise reduction load of the main muffler 20 is reduced, the main muffler 20 can be reduced in size, and the cost and weight can be reduced.

  Incidentally, FIG. 3 and FIG. 4 are graphs showing the exhaust noise reduction effect when the exhaust gas is cooled by the exhaust system silencer 10 according to the present embodiment. A broken line graph is a reference (base) to be compared, and a solid line graph is a graph when the exhaust system silencer 10 according to the present embodiment is applied. In addition, the area | region shown with the dashed-dotted line circle P is an area | region at the time of low load and low speed. From these graphs, it can be seen that if the exhaust system silencer 10 according to the present embodiment is used, the silencing effect by cooling the exhaust gas can be sufficiently obtained.

  Further, in the exhaust system silencer 10 according to the present embodiment, the exhaust heat recovery heat exchanger 22 is set independently of the exhaust pipe 14 and is connected to the exhaust pipe 14 by the conduit 24. The exhaust heat recovery heat exchanger 22 at an arbitrary position can be used as a silencer. As a result, according to the present embodiment, when there are a plurality of exhaust heat recovery heat exchangers, the exhaust heat recovery heat exchanger having the highest noise reduction effect (in this embodiment, the exhaust heat that is an EGR cooler) A recovery heat exchanger 22) can be selected.

[Second Embodiment]
Hereinafter, a second embodiment of the exhaust silencer according to the present invention will be described with reference to FIG. In addition, about the same component as 1st Embodiment mentioned above, the same number is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 5, in the exhaust silencer 50 according to the second embodiment, the outlet opening / closing means is provided on the outlet side (exhaust gas outlet 28 side) of the conduit 24 of the heat exchanger 22 for exhaust heat recovery. This is characterized in that a dynamic pressure variable valve 52 is provided.

  The dynamic pressure variable valve 52 is set to have a holding force of a valve spring (not shown) so that it is opened when the flow path switching valve 34 is closed and closed when the flow path switching valve 34 is open. Has been.

  According to the above configuration, the flow path switching valve 34 is closed at a low load immediately after engine startup and at a low speed. Accordingly, the dynamic pressure variable valve 52 is opened. Therefore, the exhaust gas flows into the pipe line 24 from the exhaust gas inlet 26 and is sent to the exhaust heat recovery heat exchanger 22. In the heat exchanger 22 for exhaust heat recovery, heat exchange is performed between the refrigerant (hot water) flowing through the heater hot water flow path 30 and the high-temperature exhaust gas, and exhaust heat is recovered and the exhaust gas itself is cooled. For this reason, the flow rate (volume) of the exhaust gas is reduced. Therefore, the noise reduction effect of the exhaust gas at low load and low speed can be obtained. After that, the exhaust gas is discharged from the exhaust gas discharge port 28 into the exhaust pipe 14 through the pipe line 24, and then sent to the main muffler 20 to be further silenced. Therefore, as in the first embodiment described above, the exhaust gas silencing effect at low load and low speed can be obtained.

  On the other hand, the flow path switching valve 34 is opened during medium and high loads and during medium and high speeds. Accordingly, the dynamic pressure variable valve 52 is closed. As a result, the pipe line 24 on the exhaust heat recovery heat exchanger 22 side from the exhaust gas inlet 26 to the exhaust gas outlet 28 functions as a resonance device having a closed end on one side. The exhaust sound of the corresponding frequency is muted. The frequency f2 of the exhaust sound on the exhaust heat recovery heat exchanger 22 side at this time is represented by f2 = C / (4 × L2). However, C is a constant.

  In addition, by making the closing position of the exhaust gas discharge port 28 by the discharge port opening / closing means including the dynamic pressure variable valve 52 variable, it is possible to expand the frequency band that can be silenced. For example, the outlet opening / closing means is constituted by a valve body capable of closing the outlet side of the conduit 24 and a spring for energizing the valve body, and the spring is formed of a material that expands and contracts according to the temperature in the vicinity of the exhaust gas outlet 28. Thus, the valve body may stroke the outlet side of the pipe line 24 in accordance with the temperature in the vicinity of the exhaust gas discharge port 28, and the pipe line length of the pipe line 24 as the resonance device may be changed. Further, a solenoid may be extended according to the temperature in the vicinity of the exhaust gas discharge port 28 using an electromagnetic valve, and a valve body provided at the tip thereof may be stroked. Furthermore, the dynamic pressure variable valve 52 may be installed at a plurality of locations on the outlet side of the pipeline 24, and the dynamic pressure variable valve 52 that opens and closes may be changed depending on conditions such as the temperature on the outlet side.

  As described above, the exhaust system silencer 50 according to the present embodiment can also provide a sufficient silencing effect from the low load to the high load or from the low speed to the high speed, as in the first embodiment. Accordingly, since the noise reduction load of the main muffler 20 is reduced, the main muffler 20 can be reduced in size, and the cost and weight can be reduced.

  Further, in the exhaust silencer 50 according to the present embodiment, the exhaust heat recovery heat exchanger 22 is set independently from the exhaust pipe 14, as in the first embodiment described above. Since it is connected to the exhaust pipe 14, the exhaust heat recovery heat exchanger 22 located at an arbitrary position can be used as a silencer. As a result, according to the present embodiment, when there are a plurality of exhaust heat recovery heat exchangers, it is possible to select the exhaust heat recovery heat exchanger having the highest noise reduction effect.

[Third Embodiment]
Hereinafter, a third embodiment of the exhaust system silencer according to the present invention will be described with reference to FIG. In addition, about the same component as 1st Embodiment mentioned above, the same number is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 6, in the exhaust silencer 60 according to the third embodiment, the outlet side (exhaust gas outlet 28 side) of the conduit 24 of the exhaust heat recovery heat exchanger 22 is used as a space portion. It is characterized in that it is inserted together with the exhaust pipe 14 into the cross section of the main muffler 20. In this case, the outlet side of the pipe line 24 has a straight shape, and its tip is inserted into the main muffler 20 as it is, and in this state, is fixed to the main muffler 20 by fixing means such as welding.

  According to the above configuration, the flow path switching valve 34 is closed at a low load immediately after engine startup and at a low speed. Therefore, the exhaust gas flows into the pipe line 24 from the exhaust gas inlet 26 and is sent to the exhaust heat recovery heat exchanger 22. In the heat exchanger 22 for exhaust heat recovery, heat exchange is performed between the refrigerant (hot water) flowing through the heater hot water flow path 30 and the high-temperature exhaust gas, and exhaust heat is recovered and the exhaust gas itself is cooled. For this reason, the flow rate (volume) of the exhaust gas is reduced. Therefore, the noise reduction effect of the exhaust gas at low load and low speed can be obtained. After that, the exhaust gas is discharged from the exhaust gas discharge port 28 into the exhaust pipe 14 through the pipe line 24, and then sent to the main muffler 20 to be further silenced.

  Further, in the present embodiment, the exhaust gas discharge port 28 is provided on the downstream side of the exhaust gas discharge port 28, and the exhaust muffler 20 has a cross-sectional area larger than that of the exhaust gas discharge port 28, and the exhaust pipe 14. Since it is connected (inserted), a silencing effect due to the expansion effect is obtained.

  By these cooling action and expansion action, the effect of silencing exhaust gas at low load and low speed can be obtained.

  On the other hand, the flow path switching valve 34 is opened during medium and high loads and during medium and high speeds. For this reason, most of the exhaust gas is sent directly to the main muffler 20 through the exhaust pipe 14. Since the cross-sectional area of the main muffler 20 is larger than the cross-sectional area of the exhaust pipe 14, when the exhaust gas is discharged from the exhaust pipe 14 into the main muffler 20, a silencing effect due to the expansion effect is obtained.

  Furthermore, in the present embodiment, as described above, the exhaust gas discharge port 28 is connected to the main muffler 20 provided on the downstream side of the exhaust gas discharge port 28 and having a larger cross-sectional area than the exhaust gas discharge port 28. Also, a silencing effect due to the expansion effect can be obtained on the exhaust heat recovery heat exchanger 22 side.

  Therefore, the expansion effect is doubled at medium and high loads and at medium and high speeds, and a mute effect corresponding to the expansion effect is obtained.

  The transmission loss of the exhaust sound due to the expansion effect is expressed as transmission loss≈ (D2 / D1) × 4 (dB), where D1 is the inner diameter of the inserted pipe and D2 is the inner diameter of the main muffler 20.

  As described above, according to the exhaust system silencer 60 according to the present embodiment, a sufficient silencing effect can be achieved from the low load to the high load, or from the low speed to the high speed, as in the first embodiment or more. Is obtained. Accordingly, since the noise reduction load of the main muffler 20 is reduced, the main muffler 20 can be reduced in size, and the cost and weight can be reduced.

  Further, in the exhaust silencer 60 according to the present embodiment, the exhaust heat recovery heat exchanger 22 is set independently from the exhaust pipe 14, as in the first embodiment described above. Since it is connected to the exhaust pipe 14, the exhaust heat recovery heat exchanger 22 located at an arbitrary position can be used as a silencer. As a result, according to the present embodiment, when there are a plurality of exhaust heat recovery heat exchangers, it is possible to select the exhaust heat recovery heat exchanger having the highest noise reduction effect.

  Furthermore, the exhaust system silencer 60 according to the present embodiment employs a configuration in which the outlet side of the conduit 24 of the exhaust heat recovery heat exchanger 22 is inserted into the cross section of the main muffler 20 and integrated by welding or the like. Therefore, the rigidity of the entire exhaust system (particularly near the main muffler 20) can be improved. In addition, as the rigidity of the entire exhaust system is improved, vibration transmission to the entire exhaust system is also greatly improved (that is, the amount of vibration transmission can be greatly reduced).

  In the above embodiment, the outlet side of the pipe line 24 of the exhaust heat recovery heat exchanger 22 is inserted into the cross section of the main muffler 20 together with the exhaust pipe 14. And the outlet side of the conduit 24 of the exhaust heat recovery heat exchanger 22 may be inserted into the cross section of the space.

[Fourth Embodiment]
Hereinafter, the fourth embodiment of the exhaust system silencer according to the present invention will be described with reference to FIGS. In addition, about the same component as 1st Embodiment mentioned above, the same number is attached | subjected and the description is abbreviate | omitted.

  FIG. 7 shows a schematic configuration diagram when the longitudinal cross-sectional structure of the exhaust system silencer 70 according to this embodiment is partly broken and viewed in a side view. FIG. 8 is a perspective view of the exhaust system silencer 70. As shown in these drawings, the exhaust system silencer 70 according to the fourth embodiment is characterized in that an exhaust heat recovery heat exchanger 72 is integrated with the outer peripheral portion of the exhaust pipe 14.

  Specifically, an exhaust heat recovery heat exchanger 72 is integrally disposed on the outer peripheral portion of the exhaust pipe 14 so as to include both the exhaust gas inlet 26 and the exhaust gas outlet 28. The heat exchanger 72 for exhaust heat recovery includes an outer casing 74 formed in a substantially cylindrical shape, and three first partition walls 76 to 80 that partition the inner space of the outer casing 74 into three gas chambers. As a result, the outer space of the heat exchanger 72 for exhaust heat recovery is divided into three in the circumferential direction of the exhaust pipe 14. Each of the first gas chamber 82 to the third gas chamber 86 is provided with a refrigerant pipe 88 for supplying a refrigerant for cooling the exhaust gas.

  Further, the exhaust gas inlet 26 formed in the exhaust pipe 14 is opened upstream of the first gas chamber 82. In addition, a communication port 90 that connects the first gas chamber 82 and the second gas chamber 84 is formed on the downstream side of the first partition wall 76 that separates the first gas chamber 82 and the second gas chamber 84. Yes. Further, on the upstream side of the second partition 78 that separates the second gas chamber 84 and the third gas chamber 86, a communication port 92 that connects the second gas chamber 84 and the third gas chamber 86 is formed. Yes. Further, the exhaust gas discharge port 28 formed in the exhaust pipe 14 is opened on the downstream side of the third gas chamber 86.

  Next, the operation and effect of this embodiment will be described.

  Basically, the exhaust system silencer 10 according to the present embodiment can also obtain the same operations and effects as the first embodiment described above.

  Briefly, the flow path switching valve 34 is closed at a low load immediately after engine startup and at a low speed. For this reason, the exhaust gas flows into the first gas chamber 82 from the exhaust gas inlet 26 and flows in the first gas chamber 82 from the upstream side to the downstream side along the longitudinal direction of the exhaust pipe 14. In this process, heat is exchanged between the low-temperature refrigerant flowing through the refrigerant pipe 88 and the high-temperature exhaust gas, and the exhaust heat is recovered and the exhaust gas itself is cooled.

  The exhaust gas that has flowed through the first gas chamber 82 flows into the second gas chamber 84 through the communication port 90 formed in the first partition wall 76. The same heat exchange action is performed in the second gas chamber 84, and then flows into the third gas chamber 86 through the communication port 92 formed in the second partition wall 78. After the same heat exchange action is performed in the third gas chamber 86, the exhaust gas flows into the exhaust pipe 14 from the exhaust gas discharge port 28 opened in the third gas chamber 86 and is sent to the main muffler 20. It is.

  Note that an exhaust gas flow (flow path) is indicated by an arrow Q in FIG.

  On the other hand, the flow path switching valve 34 is opened during medium and high loads and during medium and high speeds. For this reason, most of the exhaust gas is sent directly to the main muffler 20 through the exhaust pipe 14.

  Here, in this embodiment, the internal space of the heat exchanger 72 for exhaust heat recovery 72 is divided into three in the circumferential direction to meander the gas flow path, and the substantial flow path length L2 is larger than that in the first embodiment described above. Since it is made longer, it becomes sufficiently longer than the pipe length L1 from the exhaust gas inlet 26 to the exhaust gas outlet 28 in the exhaust pipe 14. For this reason, a phase difference is generated between the exhaust pulsation (exhaust sound pressure) on the exhaust heat recovery heat exchanger 72 side and the exhaust pulsation (exhaust sound pressure) on the exhaust pipe 14 side, and a silencing effect is obtained by the interference action between the two. can get.

  Thereafter, the silenced exhaust gas is further silenced by the main muffler 20.

  As described above, the exhaust system silencing device 70 according to the present embodiment can also provide a sufficient silencing effect from a low load to a high load or from a low speed to a high speed. Accordingly, since the noise reduction load of the main muffler 20 is reduced, the main muffler 20 can be reduced in size, and the cost and weight can be reduced.

  Further, in the exhaust system silencer 70 according to the present embodiment, the exhaust heat recovery heat exchanger 72 is integrally provided on the outer peripheral portion of the exhaust pipe 14, so that the installation space can be reduced. As a result, according to this embodiment, it can be mounted on many vehicle types.

  Further, in the exhaust system silencer 70 according to this embodiment, the internal space of the exhaust heat recovery heat exchanger 72 is divided into a plurality of chambers in the circumferential direction so that the exhaust gas flows through all the gas chambers in a certain order. Since it comprised, the flow path length can be changed into arbitrary length by changing the division | segmentation number. For this reason, the exhaust gas cooling efficiency of the heat exchanger 72 for exhaust heat recovery per unit can be increased. As a result, according to the present embodiment, the exhaust heat recovery heat exchanger 72 itself can be reduced in size.

  In the above-described embodiment, the inner space of the outer casing 74 is divided into three in the circumferential direction. Although the structure may be a two-part structure or a structure having four or more parts, the greater the number of divisions (number of chambers), the longer the exhaust gas passage length.

  Moreover, in the said embodiment, although the structure which divides | segments the internal space of the outer casing 74 in the circumferential direction was taken, it is not restricted to this, You may divide | segment the internal space of the outer casing 74 to an axial direction, or is divided | segmented. Instead, it is possible to adopt a configuration in which the flow path length is increased by forming the internal space of the outer casing 74 in a spiral shape.

  Further, in the present embodiment, the exhaust gas discharge port 28 is configured in the same manner as in the first embodiment. However, as shown in FIG. 9, the exhaust gas discharge port 28 has a discharge port opening / closing valve 94 as a discharge port opening / closing means. By providing this, a configuration similar to that of the second embodiment described above can be obtained.

[Supplementary explanation of the embodiment]
In each of the embodiments described above, an EGR cooler (including a heat exchanger based on the EGR cooler) is used as a heat exchanger for exhaust heat recovery. However, the present invention is not limited to this, and other heat exchangers are used. A configuration may be adopted.

1 is an overall configuration diagram of an exhaust heat recovery system according to a first embodiment. It is an enlarged view which shows the exhaust system silencer shown by FIG. It is a graph (exhaust sound overall) which shows the exhaust sound reduction effect at the time of applying an exhaust system silencer. It is a graph (at the time of acceleration) which shows the exhaust noise reduction effect at the time of applying an exhaust system silencer. It is an enlarged view corresponding to FIG. 2 which shows the whole structure of the exhaust-system silencer which concerns on 2nd Embodiment. It is an enlarged view corresponding to FIG. 2 which shows the whole structure of the exhaust-system silencer which concerns on 3rd Embodiment. It is a partially cutaway sectional view when the longitudinal sectional structure of the exhaust system silencer according to the fourth embodiment is viewed in side view. It is a perspective view of the exhaust system silencer shown by FIG. FIG. 10 is a partially cutaway cross-sectional view corresponding to FIG. 7 showing a modification in which a dynamic pressure variable valve is provided in an exhaust system silencer according to a fourth embodiment.

Explanation of symbols

10 Exhaust system silencer 14 Exhaust pipe 16 Engine 20 Main muffler (space part)
22 Exhaust heat recovery heat exchanger 24 Pipe line 26 Exhaust gas inlet 28 Exhaust gas outlet 34 Flow path switching valve (flow path switching means)
50 Exhaust system silencer 52 Dynamic pressure variable valve (exhaust port opening / closing means)
60 Exhaust system silencer 70 Exhaust system silencer 82 First gas chamber 84 Second gas chamber 86 Third gas chamber 94 Discharge port opening / closing valve (discharge port opening / closing means)

Claims (5)

Set the flow path switching means that can be opened and closed at a predetermined position of the exhaust pipe connecting the engine and the muffler,
An exhaust gas inlet of an exhaust heat recovery heat exchanger that recovers exhaust heat by exchanging heat with the exhaust gas is set upstream of the flow path switching means, and exhaust heat recovery is set downstream of the flow path switching means. By setting the exhaust gas exhaust port of the heat exchanger, the exhaust heat recovery heat exchanger is used as a means for silencing exhaust gas,
Further, the exhaust heat recovery heat exchanger is integrally provided on the outer periphery of the exhaust pipe, and the interior of the exhaust heat recovery heat exchanger is divided into a plurality of chambers. The exhaust gas introduced from the exhaust gas introduction port passes through the plurality of chambers in order according to a predetermined order, and then is exhausted from the exhaust gas discharge port. The exhaust gas introduction port enters the first chamber in the predetermined order. And the exhaust outlet is formed in the last chamber in a determined sequence,
In addition, the flow path length from the exhaust gas inlet to the exhaust gas outlet through the exhaust heat recovery heat exchanger is longer than the pipe length from the exhaust gas inlet to the exhaust gas outlet in the exhaust pipe. Set longer,
An exhaust system silencer characterized by that. The exhaust gas discharge port is provided with a discharge port opening / closing means capable of opening and closing the exhaust gas discharge port.
The exhaust system silencer according to claim 1, wherein Set the flow path switching means that can be opened and closed at a predetermined position of the exhaust pipe connecting the engine and the muffler,
An exhaust gas inlet of an exhaust heat recovery heat exchanger that recovers exhaust heat by exchanging heat with the exhaust gas is set upstream of the flow path switching means, and exhaust heat recovery is set downstream of the flow path switching means. By setting the exhaust gas exhaust port of the heat exchanger, the exhaust heat recovery heat exchanger is used as a means for silencing exhaust gas,
Further, the exhaust gas discharge port is connected to a space provided downstream of the exhaust gas discharge port and having a larger cross-sectional area than the exhaust gas discharge port.
An exhaust system silencer characterized by that. Furthermore, the flow path switching means is in a closed state at low load or low speed, and is in an open state at medium high load or medium high speed.
The exhaust system silencer according to any one of claims 1 to 3, wherein The exhaust heat recovery heat exchanger is set independently from the exhaust pipe, and is connected to the exhaust pipe by piping.
The exhaust system silencer according to any one of claims 1 to 4, wherein

Images