JP2008053080A - Exhaust system of fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust system of a fuel cell which reduces air flow noise. <P>SOLUTION: The exhaust system of fuel cell includes a muffler 2 which has sound absorption portion 11, an exhaust pipe 1 in which exhaust gas exhausted from the fuel cell flows and penetrates through the muffler 2, and a pressure control valve 3 which is installed inside the exhaust pipe 1 located inside the sound absorption portion 11 of the muffler 2 and controls the pressure of the fuel cell by adjusting the opening degree of the exhaust pipe 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an exhaust system for a fuel cell.

  In a vehicle equipped with a fuel cell, noise is generated when exhaust gas passes through the exhaust pipe, as in a vehicle equipped with an internal combustion engine. Particularly when the exhaust gas passes through a pressure regulating valve that adjusts the pressure in the fuel cell, a loud noise is generated. As a means for reducing this noise, a method using a silencer is generally employed.

  In general, the larger the flow rate and pressure of the exhaust gas, the greater the airflow noise generated from the pressure regulating valve. Accordingly, when the output of the fuel cell is large, the flow rate and pressure of the exhaust gas also increase, so that the airflow noise becomes very large. The airflow sound is classified into discharge sound emitted from the exhaust port and radiated sound transmitted through the exhaust pipe.

  The silencer provided on the downstream side of the pressure regulating valve has an effect of attenuating gas vibration and reducing the sound on the downstream side of the silencer. Thereby, the discharge sound emitted from the exhaust port is reduced, and at the same time, the radiated sound transmitted from the exhaust pipe on the downstream side of the silencer is also reduced. On the other hand, the radiated sound transmitted from the exhaust pipe upstream of the silencer is not relatively reduced, and particularly, a loud sound is emitted from the exhaust pipe between the pressure regulating valve and the silencer.

In order to reduce the sound from the exhaust pipe, Patent Document 1 discloses a technique for reducing the radiated sound transmitted from the exhaust pipe by shortening the exhaust pipe between the pressure regulating valve and the silencer.
Japanese Patent Laid-Open No. 2005-261751

  However, even when Patent Document 1 is used, a radiated sound is emitted from the exhaust pipe between the pressure regulating valve and the silencer, and when the thickness of the pressure regulating valve body is increased to reduce this, the size of the pressure regulating valve is reduced. As it grows, the mass increases.

  An object of the present invention is to provide a small and lightweight exhaust system for a fuel cell in which airflow noise generated from a pressure regulating valve is effectively reduced.

  In the present invention, a silencer having a sound absorbing portion, exhaust gas discharged from the fuel cell flows, an exhaust pipe penetrating the silencer, and provided inside an exhaust pipe located inside the sound absorbing portion of the silencer, A pressure regulating valve that regulates the gas pressure of the fuel cell by adjusting the opening.

  According to the present invention, it is possible to effectively reduce the air flow noise generated by the pressure regulating valve by providing the pressure regulating valve inside the silencer.

  The configuration of the first embodiment of the present invention will be described with reference to the schematic configuration diagrams of FIGS. 1 is a schematic view showing a cross section of a flow path of an exhaust system of a fuel cell, and FIG. 2 is a cross-sectional view taken along the line AA of FIG.

  The exhaust system of this embodiment includes an exhaust pipe 1 through which exhaust gas of a fuel cell (not shown) flows, a silencer (silencer) 2 through which the exhaust pipe 1 passes, and an exhaust pipe located inside the silencer 2 1 is provided with a pressure regulating valve (pressure regulating valve) 3 provided inside 1 and a motor 4 that rotates the pressure regulating valve 3 inside the exhaust pipe 1.

  One end of the exhaust pipe 1 is connected to the gas discharge side of the fuel cell, and the other end communicates with the outside air. Exhaust gas discharged from the fuel cell is discharged to the outside through the exhaust pipe 1. The pipe wall of the exhaust pipe 1 is provided with a number of flow path holes 13 at locations facing the silencer 2.

  The diameter φ of the flow path hole 13 is desirably small so that the sound absorbing portion 11 described later is not scattered inside the exhaust pipe 1, and the diameter φ is about 3 to 4 mm. It is desirable to reduce the value.

  The number of the flow path holes 13 per unit area of the exhaust pipe 1 is determined in the vicinity of the pressure control valve 3 to be described later, in other words, in a movable range in which the pressure control valve 3 rotates in the exhaust pipe 1. The number is less than the number of flow path holes 13 provided in the other exhaust pipes 1. When the pressure regulating valve 3 is in the fully closed state or close to the fully closed state, if there are many flow path holes 13 in the vicinity of the pressure regulating valve 3, the pressure change with respect to the slight opening change of the pressure regulating valve 3 becomes large. Although the control of the pressure regulating valve 3 becomes difficult, the control of the pressure regulating valve 3 can be facilitated by reducing the number of flow passage holes 13 in the vicinity of the pressure regulating valve 3. Further, the diameter of the flow path hole 13 may be reduced instead of reducing the number of the flow path holes 13 per area of the exhaust pipe 1 as compared with the other exhaust pipes 1.

  The silencer 2 includes a sound absorbing part 11 through which the exhaust pipe 1 penetrates to reduce the flow noise of the exhaust gas flowing through the exhaust pipe 1 and a water absorbing part 12 that absorbs moisture inside the silencer 2. The sound absorbing portion 11 is disposed upstream of the water absorbing portion 12 with respect to the flow direction of the exhaust gas.

  The silencer 2 is arranged so that the downstream side in the exhaust gas flow direction is lower than the upstream side. In this embodiment, the silencer 2 is arranged in the vertical direction so that the exhaust gas flows along the vertical direction.

  In addition, when the apparatus which collect | recovers the water in exhaust gas is provided in the upstream of the flow direction of exhaust gas, you may arrange | position so that the upstream in the flow direction of exhaust gas may become lower than the downstream. .

  The sound absorbing unit 11 is configured by filling glass wool or the like, for example. Inside the sound absorbing portion 11, a partition plate 16 provided in a direction orthogonal to the flow direction of the exhaust gas is provided, and the sound absorbing portion 11 is upstream of the upstream portion 11a with respect to the flow direction of the exhaust gas by the partition plate 16. And the downstream portion 11b on the downstream side.

  The partition plate 16 is disposed in the vicinity of the rotary shaft 17 of the pressure regulating valve 3. The partition plate 16 includes a communication hole 15 that communicates the upstream portion 11 a and the downstream portion 11 b of the sound absorbing portion 11 partitioned by the partition plate 16.

  A plurality of communication holes 15 are provided in the partition plate 16, and the number and the diameter of the holes can maintain the gas seal performance upstream of the pressure regulating valve 3 when the pressure regulating valve 3 is fully closed, and the water in the upstream portion 11 a can flow downstream. It is set so that it can be discharged to the part 11b.

  The water absorption part 12 is configured by filling a chamois or the like having a higher water absorption than the sound absorption part 11 and absorbs moisture that has entered the silencer 2. The water absorbed by the water absorption part 12 is discharged to the outside from the drain hole 14 provided in the bottom 10a of the case 10. The drain hole 14 is desirably provided at the lowest position in the silencer 2. In addition, you may provide in several places in the bottom part 10a, and it can drain from the silencer 2 irrespective of the attitude | position of the silencer 2 by this.

  The pressure regulating valve 3 is provided in the exhaust pipe 1 immediately upstream of the partition plate 16 and has substantially the same shape as the cross-sectional shape of the exhaust pipe 1 with respect to the flow direction of the exhaust gas. The pressure regulating valve 3 is rotated in the exhaust pipe 1 by the motor 4 via the rotating shaft 17 and adjusts the opening degree of the pressure regulating valve 3, that is, the gap between the exhaust pipe 1 and the pressure regulating valve 3. The pressure of the exhaust pipe 1 on the upstream side, that is, the gas pressure of the fuel cell is adjusted. In addition, when the opening degree of the pressure regulation valve 3 is large, the gas pressure of a fuel cell becomes low, and when the opening degree of the pressure regulation valve 3 is small, the gas pressure of a fuel cell becomes high.

  Even when the pressure regulating valve 3 is rotated by the exhaust pipe 1, the pressure regulating valve 3 is arranged so that all of the pressure regulating valve 3 is accommodated in the silencer 2. Thereby, the airflow sound generated by the pressure regulating valve 3 can be effectively reduced by the silencer 2. The silencer 2 may be provided so as to extend long upstream of the exhaust pipe 1.

  With the above configuration, by arranging the silencer 2 outside the exhaust pipe 1 provided with the pressure regulating valve 3, it is possible to reduce the sound of the airflow generated by the pressure regulating valve 3.

  Exhaust gas discharged from the fuel cell generates airflow noise in the exhaust pipe 1, and particularly when a large airflow noise is generated when passing through the pressure regulating valve 3 that adjusts the gas pressure of the fuel cell. The silencer 2 is disposed on the outer periphery of the exhaust pipe 1 arranged in the air pipe, and the air flow noise of the exhaust pipe 1, particularly the vibration energy of the air flow sound is propagated to the sound absorbing portion 11 through the flow path hole 13, By silencing with the sound absorption part 11, the airflow sound of the discharge pipe 1, especially the airflow sound produced by the pressure regulation valve 3 can be reduced.

  Further, since water is contained in the exhaust gas of the fuel cell, the water in the exhaust gas enters the sound absorbing portion 11 through the flow path hole 13 and is absorbed by the sound absorbing portion 11. Thereby, although there exists a possibility that the noise reduction performance of the sound absorption part 11 may be worsened, the water which penetrate | invaded the inside of the sound absorption part 11 moves to the downstream side of the silencer 2 by gravity by arrange | positioning the silencer 2 to a perpendicular direction. . However, there is a possibility that a part of water accumulates inside the sound absorbing portion 11 due to the capillary phenomenon of the sound absorbing portion 11.

  In this embodiment, by providing the water absorbing part 12 having high water absorption at a position lower than the sound absorbing part 11 in contact with the sound absorbing part 11, in addition to the movement of water due to gravity, the sound absorbing part 11 Water is positively moved to the water absorption part 12 having a water absorption rate higher than 11. As a result, the moisture content of the sound absorbing portion 11 can be lowered, and the moisture content of the sound absorbing portion 11 can be reduced to 4% or less, which has a great silencing effect in the sound absorbing portion 11. The channel hole 13 may also be provided in the tube wall of the exhaust pipe 1 that contacts the water absorbing portion 12. Thereby, the silencing effect in the water absorption part 12 can be improved, and airflow sound can be further reduced.

  Further, the sound absorbing portion 11 is separated into an upstream portion 11a and a downstream portion 11b by the partition plate 3, and water entering the upstream portion 11a from the flow path hole 13 is transferred to the downstream portion 11b by the partition plate 3. However, the through-hole 15 provided in the partition plate 3 allows water to move from the upstream portion 11a to the downstream portion 11b, and the silencing performance in the upstream portion 11a is not deteriorated. In addition, when used in a cold region, if water remains in the vicinity of the regulating valve 3 and the rotary shaft 17 after the power generation of the fuel cell is completed, the water freezes and the pressure regulating valve 3 is activated at the next start-up. Although it may not operate normally, in this embodiment, since water moves from the upstream portion 11a to the downstream portion 11b through the through hole 15, malfunction of the pressure regulating valve 3 due to freezing of water can be suppressed. .

  The effect of 1st Embodiment of this invention is demonstrated.

  In this embodiment, the silencer 2 through which the exhaust pipe 1 connected to the discharge side of the fuel cell passes, and the inside of the silencer 2, provided inside the exhaust pipe 1 and adjusting the opening degree of the fuel cell. By providing the pressure regulating valve 3 that adjusts the gas pressure, the silencer 2 can reduce the sound of the airflow in the exhaust pipe 1, particularly the sound of the airflow generated by the pressure regulating valve 3. Moreover, by providing the pressure regulating valve 3 inside the silencer 2, the exhaust system can be made smaller and lighter than when the pressure regulating valve and the silencer are separately provided.

  Regardless of the opening of the pressure regulating valve 3, the entire pressure regulating valve 3 is provided inside the silencer 2, so that airflow noise generated by the pressure regulating valve 3 can be reliably reduced.

  The silencer 2 includes a sound absorbing part 11 and a water absorbing part 12 that has higher water absorption than the sound absorbing part 11 and is connected in series to the flow direction of the exhaust gas, and the water absorption part 12 is arranged in the flow direction of the exhaust gas. On the other hand, by providing it at a position downstream of the sound absorbing unit 11 and lower than the sound absorbing unit 11, the water absorbed by the sound absorbing unit 11 is moved to the water absorbing unit 12 by gravity, and water is absorbed from the sound absorbing unit 11. Drain. Further, by providing the sound absorbing portion 11 and the water absorbing portion 12 in contact with each other, water can be actively moved from the sound absorbing portion 11 to the water absorbing portion 12, and the water drainage of the sound absorbing portion 11 is further improved. Can do. Thereby, deterioration of the silencing effect of the sound absorption part 11 by adhesion of water can be prevented.

  Since the flow path hole 13 for propagating the gas vibration energy of the exhaust pipe 1 to the sound absorption part 11 is provided on the tube wall of the exhaust pipe 1 facing the sound absorption part 11, the flow path hole 13 even when the pressure regulating valve 3 is closed. The gas flows through the sound absorbing unit 11, but by providing the partition plate 16 that separates the sound absorbing unit 11 with respect to the flow direction of the exhaust gas, movement of the gas inside the sound absorbing unit 11 can be prevented. The gas sealing performance when the opening of the pressure regulating valve 3 is reduced can be maintained.

  By providing the partition plate 16 with the through hole 15 that allows the upstream portion 11a and the downstream portion 11b to communicate with each other, water can be moved from the upstream portion 11a to the downstream portion 11b. Deterioration can be prevented. Further, when the fuel cell is stopped, water can be prevented from collecting in the upstream portion 11a, particularly in the vicinity of the pressure regulating valve 3. Thereby, when the fuel cell is stopped in a cold region, for example, water freezes in the vicinity of the pressure regulating valve 3, and malfunction of the pressure regulating valve 3 caused by ice at the next start-up can be suppressed.

  In the exhaust pipe 1 in the vicinity of the pressure regulating valve 3, that is, in the movable range of the pressure regulating valve 3, the number of flow path holes 13 per unit area is smaller than the number of flow path holes 13 per unit area of the other exhaust pipes 1. By doing so, when the opening degree of the pressure regulation valve 3 is small, the pressure change with respect to the opening degree change of the pressure regulation valve 3 can be made small, and control of the pressure regulation valve 3 can be made easy.

  Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment will be described with a focus on differences from the first embodiment. FIG. 3A is a schematic cross-sectional view in the vicinity of the pressure regulating valve 3 when the pressure regulating valve 3 is fully closed, and FIG. 3B is a pressure regulating valve when the pressure regulating valve 3 is fully opened. 3 is a schematic sectional view of the vicinity of 3. FIG.

  In this embodiment, the rotation shaft 20 that connects the pressure regulating valve 3 and the motor 4 is provided with a conduction hole 21.

  When the pressure regulating valve 3 is open, at least when it is fully open, the conduction hole 21 communicates with the communication hole 15a of the partition plate 3 located on the back surface of the rotating shaft (operation part) 20, and the upstream part 11a and the downstream. The part 11b is communicated. Further, when the pressure regulating valve 3 is fully closed or the opening degree is small, the communication hole 21 is not communicated with the communication hole 15 a, and the communication hole 15 a is closed by the rotating shaft 20.

  In addition, when the opening degree of the pressure regulating valve 3 is fully closed, a part of the communication hole 15 of the partition plate 3 may be closed with another member.

  The effect of 2nd Embodiment of this invention is demonstrated.

  When the rotation shaft 20 is provided with a conduction hole 21 and the opening of the pressure regulating valve 3 is at least fully open, the conduction hole 21 and the communication hole 15a located on the back surface of the rotation shaft 20 are communicated with each other, so that the upstream portion 11a The downstream part 11b can be communicated, water can be moved from the upstream part 11a to the downstream part 11b, and the drainage of the upstream part 11a can be improved. Further, when the opening degree of the pressure regulating valve 3 is fully closed or small, the communication hole 15a is closed by the rotary shaft 20, thereby preventing gas movement inside the sound absorbing portion 11 and maintaining gas sealing performance. be able to.

  Next, a third embodiment of the present invention will be described with reference to FIG. The third embodiment will be described with a focus on differences from the first embodiment. FIG. 4 is a cross-sectional view of the flow path hole 22 provided in the exhaust pipe 1 near the pressure regulating valve 3.

  In this embodiment, the flow path hole 22 of the exhaust pipe 1 near the pressure regulating valve 3 is chamfered. Here, C chamfering is applied to the channel hole 22. By chamfering the flow path hole 22, the movement of water from the flow path hole 22 to the sound absorbing unit 11 is promoted. In the vicinity of the pressure regulating valve 3, the water in the exhaust pipe 1 can be surely drained to the sound absorbing portion 11, and the water in the exhaust pipe 1 can be prevented from freezing in cold regions. The C chamfer is provided in the flow path hole 22 in the movable range of the pressure regulating valve 3.

  Instead of chamfering the flow path hole 22, the flow path hole 22 may have a substantially R-shaped nozzle shape as shown in FIG. Further, the thickness of the exhaust pipe 1 in the vicinity of the pressure regulating valve 3 may be reduced.

  The effect of the third embodiment of the present invention will be described.

  The flow path hole 13 of the exhaust pipe 1 propagates the air vibration energy in the exhaust pipe 1 to the sound absorbing portion 11, but the exhaust gas contains water, and water is removed from the exhaust pipe 1 by the surface tension. 11 may be difficult to move to. In particular, when such a phenomenon occurs in the vicinity of the pressure regulating valve 3, water may freeze in a cold region after the fuel cell is stopped, and the malfunction of the pressure regulating valve 3 may occur at the next startup.

  In this embodiment, by chamfering the flow path hole 22 in the vicinity of the pressure regulating valve 3, water can easily enter the sound absorbing portion 11 from the exhaust pipe 1 and the drainage performance in the vicinity of the pressure regulating valve 3 is improved. As a result, by reliably removing the water in the vicinity of the pressure regulating valve 3, it is possible to suppress freezing of the water in the vicinity of the pressure regulating valve 3 that may occur after the fuel cell is stopped in a cold region or the like. The malfunction of the pressure regulating valve 3 can be suppressed.

  It goes without saying that the present invention is not limited to the above-described embodiments, and includes various modifications and improvements that can be made within the scope of the technical idea.

It is a schematic block diagram of the exhaust system of 1st Embodiment of this invention. It is AA sectional drawing of FIG. It is a schematic block diagram of the pressure regulation valve vicinity of 2nd Embodiment of this invention, (a) It is the state in which the pressure regulation valve is fully closed. (B) The pressure regulating valve is fully open. It is sectional drawing of the flow-path hole of 3rd Embodiment of this invention. It is sectional drawing which shows the example of a change of the flow-path hole of 3rd Embodiment of this invention.

Explanation of symbols

1 Exhaust pipe 2 Silencer (silencer)
3 Pressure regulating valve (pressure regulating valve)
5 Motor 11 Sound absorption part 11a Upstream part 11b Downstream part 12 Water absorption part 13 Channel hole 14 Drainage hole 15 Communication hole 16 Partition plate 20 Rotating shaft (operation part)

Claims (10)

A silencer having a sound absorbing part;
Exhaust gas discharged from the fuel cell flows, and an exhaust pipe penetrating the silencer;
A pressure adjusting valve provided inside the exhaust pipe located inside the sound absorbing portion of the silencer and adjusting a gas pressure of the fuel cell by adjusting an opening degree of the fuel. Battery exhaust system.   2. The fuel cell exhaust system according to claim 1, wherein the pressure regulating valve is positioned inside the muffler regardless of an opening degree of the pressure regulating valve. The muffler includes a water absorption part connected in series with the sound absorption part with respect to the flow direction of the exhaust gas,
3. The fuel cell exhaust system according to claim 1, wherein the exhaust pipe includes a flow path hole that communicates the inside of the exhaust pipe with the sound absorbing portion. 4. The water absorption part is located downstream of the sound absorption part and lower than the sound absorption part with respect to the flow direction of the exhaust gas,
4. The fuel cell exhaust system according to claim 3, wherein the silencer includes a drain hole that communicates the water absorption part and the outside of the silencer. 5.   The exhaust system for a fuel cell according to claim 3 or 4, wherein the water absorption part has higher water absorption than the sound absorption part.   The exhaust system for a fuel cell according to any one of claims 1 to 5, wherein the silencer includes a partition plate that separates the sound absorbing portion in a flow direction of the exhaust gas.   The exhaust system for a fuel cell according to claim 6, wherein the partition plate includes a communication hole that communicates between the sound absorbing parts to be separated. An operating part that opens or closes part of the drainage hole in conjunction with the pressure regulating valve;
The exhaust system for a fuel cell according to claim 7, wherein the operating unit closes at least a part of the drain hole when the opening of the pressure regulating valve is at least fully closed.   The exhaust of the fuel cell according to any one of claims 1 to 8, wherein the flow path hole located in a movable range in which the pressure regulating valve is movable inside the exhaust pipe has a chamfered portion. system.   The number of the flow path holes per unit area located in a movable range in which the pressure regulating valve is movable inside the exhaust pipe is smaller than that of the exhaust pipe per unit area other than the movable range. An exhaust system for a fuel cell according to any one of claims 1 to 9.