JP2005073463A - Exhaust system for fuel-cell automobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust system for a fuel-cell automobile that discharges condensed water to the outside of a tube in front of a muffler, and can prevent deterioration of acoustic properties of an acoustic material. <P>SOLUTION: In the exhaust system of the fuel-cell automobile comprising the muffler that muffles the sound of an exhaust sound, and a tube member connected to the front of the muffler, at least part 3A of the tube member is formed into a double-tube structure, composed of an outer tube 4 and an inner tube 6 that is arranged inside the outer tube 4 with a prescribed space 5 therebetween; and at least one or more small holes 8, 9 for discharging the condensed water are formed in the outer tube 4 and the inner tube 6. The condensed water is discharged to the outside of the tube from the small hole 9 of the outer tube 4 passing through the space 5, after flowing into the space 5 via the small hole 8 formed in the inner tube 6. The condensed water is thereby prevented from flowing into the muffler, and deterioration of the acoustic properties of the acoustic material can be prevented. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an exhaust device used in a fuel cell vehicle, and more particularly, to a drainage technique for discharging condensed water in front of a muffler.

  For example, a sound absorbing muffler for a general internal combustion engine is filled with a housing, an inner pipe penetrating through the housing, a silencer chamber surrounded by the housing and the inner pipe, and the silencer chamber. A plurality of small holes are formed in the inner pipe (see, for example, Patent Documents 1 and 2).

  As shown in FIG. 5, the silencer described in Patent Document 1 is provided with an inner pipe 103 formed through a plurality of small holes 102 in a housing 101 so as to surround the inner pipe 103. The material 104 is provided.

  As shown in FIG. 6, the exhaust silencer described in Patent Document 2 includes glass wool between an inner tube 106 in which a large number of small holes 105 are formed on a side surface and an outer tube 107 that covers the outer periphery of the inner tube 106. The sound absorbing material 108 made of the structure is filled.

  For example, in the silencer (sound absorbing muffler) described in Patent Document 1, the sound wave of the exhaust noise introduced into the inner pipe 103 is propagated into the silencer chamber through the plurality of small holes 102, and the sound absorbing material 104. The acoustic energy is attenuated by friction and the noise is silenced. Similarly, in the exhaust silencer described in Patent Document 2, the noise is silenced by the sound-absorbing material 108 in the silencer chamber through the small hole 105 formed in the inner pipe 106. The small holes 102 and 105 formed in the inner pipe 103 and the inner pipe 106 usually have a diameter of 3 mm (3Φ) or 4 mm (4Φ) in the case of a general passenger car.

  In addition, although not a muffler, in order to prevent a decrease in the temperature of exhaust gas reaching the catalytic converter disposed in the downstream portion, a structure having a double exhaust pipe has been proposed (see, for example, Patent Document 3). ).

As shown in FIG. 7, the exhaust double pipe described in Patent Document 3 has an outer pipe 109 and an inner pipe 110 arranged substantially concentrically with a predetermined gap with respect to the outer pipe 109. It is structured.
JP 2002-47910 A (Pages 2 and 3; FIGS. 1 and 2) JP 2003-41924 A (pages 3 and 4; FIGS. 2 and 3) JP 2003-184548 A (2nd and 3rd pages, FIG. 1)

  By the way, in the automobile industry, development of a fuel cell vehicle is being promoted as an alternative to an internal combustion engine using gasoline as a fuel due to the recent demand for clean energy. In a fuel cell vehicle, for example, oxygen (O 2), nitrogen (N 2), water (water vapor) (H 2 O), etc. are discharged from the muffler, but more condensed water is produced than an internal combustion engine using gasoline or the like as fuel. Discharged.

  For this reason, when the muffler for an internal combustion engine described in Patent Documents 1 and 2 is used in a fuel cell vehicle, the amount of condensed water flowing into the sound absorbing material from a small hole formed in the inner pipe or the inner pipe increases. For example, when the moisture content of the sound-absorbing material is 4% or more, the sound-absorbing performance gradually deteriorates so that sound waves are not absorbed, and the discharge sound performance deteriorates.

  Therefore, a method of draining and removing the condensed water that has flowed into the sound absorbing material can be considered, but the condensed water stored in the sound absorbing material due to the capillary phenomenon is hardly discharged. In particular, in the case of a fuel cell vehicle, in addition to moisture generated by a chemical reaction, condensed water is generated due to a difference in exhaust pipe system temperature, and the amount of generated moisture is considerably larger than that of a gasoline engine. Moreover, although the tube provided in front of the muffler is a single pipe or a double pipe, it does not have a structure for discharging condensed water as in the structure of Patent Document 3.

  As a method for draining condensed water, it is conceivable to form a small hole in the tube. However, if the small hole is simply formed, condensed water can be discharged, but the sound in the pipe leaks and the noise outside the pipe increases. Further, when the number of small holes is increased in order to increase the drainage efficiency of the condensed water, the sound in the pipe is more likely to leak and the noise outside the pipe is increased.

  Therefore, the present invention has been made to solve the above-described problems, and even when there is a large amount of condensed water, the sound absorbing material can be maintained without deterioration in performance, and the condensed water before flowing into the muffler. It is an object of the present invention to provide an exhaust device for a fuel cell vehicle capable of discharging exhaust gas.

  According to a first aspect of the present invention, there is provided an exhaust system for a fuel cell vehicle comprising a muffler for suppressing exhaust sound and a tube member connected to the front of the muffler. And a double pipe structure comprising an inner pipe provided inside with a predetermined space with respect to the outer pipe, and a small size for discharging at least one condensed water to the outer pipe and the inner pipe. A hole is formed.

  According to a second aspect of the present invention, there is provided an exhaust system for a fuel cell vehicle according to the first aspect, wherein a small hole formed in the inner pipe is provided on the upstream side where the exhaust flows in the double pipe structure portion. In addition, a small hole formed in the outer pipe is provided on the downstream side in which the exhaust flows.

  A third aspect of the invention is an exhaust system for a fuel cell vehicle according to the first or second aspect, wherein a plurality of small holes formed in the outer pipe and the inner pipe are formed, and the plurality of small holes are formed. The holes are arranged in a line along the exhaust outflow direction at predetermined intervals.

  According to a fourth aspect of the present invention, there is provided an exhaust device for a fuel cell vehicle according to any one of the first to third aspects, wherein a sound deadening member is provided in the space portion between the outer tube and the inner tube. Is provided.

  According to the first aspect of the present invention, a part of the tube member provided in front of the muffler has a double tube structure including an outer tube and an inner tube, and a small hole for discharging condensed water to the inner tube and the outer tube. Therefore, the condensed water can be discharged from the small hole to the outside of the tube member, and the condensed water can be prevented from entering the muffler. Therefore, there is no impregnation of condensed water into the sound absorbing material in the muffler, and even if there is a large amount of condensed water, the performance of the sound absorbing material is not deteriorated and the sound absorbing action can be maintained. In addition, according to the present invention, since condensed water is not stored in the muffler, corrosion inside the muffler can be prevented, and noise reduction performance due to freezing and generation of abnormal noise in the muffler due to freezing can be prevented in cold regions. In addition, the crack of the muffler due to the volume expansion of the condensed water accumulated in the muffler is eliminated, and the product reliability is improved.

  According to the second aspect of the present invention, since the small hole formed in the inner pipe is provided on the upstream side where the exhaust flows and the small hole formed in the outer pipe is provided on the downstream side, the inside of the tube member disposed in front of the muffler The condensed water flowing through the inner tube can be discharged to the space between the outer tube and the inner tube through the small hole of the inner tube, and then discharged out of the tube member through the small hole formed in the outer tube. Therefore, according to the present invention, the condensed water can be reliably discharged in front of the muffler.

  According to the invention described in claim 3, since a plurality of small holes formed in the outer pipe and the inner pipe are formed, and the plurality of small holes are arranged in a line along the exhaust outflow direction, a large amount of condensed water is generated. Even in such a case, the condensed water can be discharged sequentially from the plurality of small holes.

  According to the invention described in claim 4, since the sound deadening member is provided in the space portion between the outer tube and the inner tube, the sound can be silenced in the double tube structure portion, and the leakage sound from the outer tube can be reduced. Can do. Moreover, according to this invention, the mechanical strength of a tube member increases with this silencer member, and it can prevent the double pipe structure part from being crushed by the external force.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.

[Configuration of exhaust system]
1 is an overall perspective view of an exhaust device for a fuel cell vehicle, FIG. 2 is an enlarged cross-sectional view of a main part of a tube member having a double-pipe structure, and FIG. FIG. 3B is a partially enlarged plan view showing a part of the inner tube in which a small hole is formed, and FIG. 4 is a perspective view of the inner tube to which a silencing member is attached. It is.

  As shown in FIG. 1, an exhaust device 1 for a fuel cell vehicle according to the present embodiment includes a muffler 2 that silences exhaust noise and a tube member 3 that is connected in front of the muffler 2.

  The muffler 2 is a muffler partially using a sound absorbing material, which is also used in an internal combustion engine. The muffler 2 has a structure in which a sound absorbing material such as glass wool, rock wool, stainless wool, or carbon fiber is filled in a partial space surrounded by a shell, an end plate, and an air pipe.

  A plurality of small holes for guiding the exhaust sound to the sound absorbing material are formed in the air pipe. In the case of a muffler for an internal combustion engine that uses conventional gasoline or the like as a fuel, this hole has a possibility that the carbon may adhere to the hole due to the generation of carbon and the mixture of oil components, thereby closing the hole. Often 3 mm (Φ3) or more. However, in the fuel cell vehicle, since the exhaust air does not contain impurities, for example, the diameter of the hole is set to 0.1 mm (Φ0.1) to 1 mm (Φ1). Thereby, even if condensed water flows into the muffler 2, it is difficult for the condensed water to flow to the sound absorbing material through this hole.

  The tube member 3 is made of a pipe having a circular cross section attached to the front of the muffler 2. Air exhaust generated in the air system discharged from the fuel cell stack and, for example, oxygen (O 2), nitrogen (N 2), water (water vapor) (H 2 O), and the like flow into the tube member 3. In addition to the water generated by the chemical reaction in the fuel cell stack, condensed water generated by the piping system temperature difference flows through the tube member 3.

  In the present embodiment, the tube member 3A in the vicinity of the tube member 3 that is connected to the muffler 2 is connected to the outer tube 4 and a predetermined space with respect to the outer tube 4 as shown in FIG. It has a double structure consisting of an inner tube 6 provided inside with a portion 5. As shown in FIG. 1, flange portions 7 for connection are formed at both ends of the tube member 3 having a double structure.

  Both the outer tube 4 and the inner tube 6 are formed as pipes having a substantially circular cross section. The inner tube 6 has a slightly shorter overall length than the outer tube 4 and is fixed to the outer tube 4 by caulking the outer tube 4 at both ends thereof. The inner tube 6 has a smaller diameter than the outer tube 4 so as to form a predetermined space 5 with respect to the outer tube 4.

  As shown in FIG. 2, a plurality of small holes 8 for discharging condensed water are formed in the inner pipe 6. These small holes 8 are formed on the bottom side of the inner pipe 6 and on the upstream side where exhaust flows in the double pipe structure. Similarly, a plurality of small holes 9 for discharging condensed water are also formed in the outer pipe 4, and these small holes 9 are on the bottom side of the outer pipe 4 on the downstream side where exhaust flows in the double pipe structure portion. Is provided.

  As shown in FIG. 3, the small holes 8 formed in the inner pipe 6 are arranged in a line along the exhaust gas outflow direction at a predetermined interval. In the present embodiment, three rows are formed with four small holes 8 as one row. Similarly, the small holes 9 formed in the outer tube 4 are similarly arranged in a line along the exhaust outflow direction at a predetermined interval. In the present embodiment, two small holes 9 are formed in three rows as one row.

  As described above, when the small holes 8 and 9 formed in the inner pipe 6 and the outer pipe 4 are arranged in a line along the exhaust outflow direction at a predetermined interval, it is ensured that even when a large amount of condensed water is generated, Condensed water can be discharged (drained) sequentially from the small holes 8 and 9. For example, when the amount of condensate is small, the condensate can be discharged from the small holes 8 and 9 provided in the forefront in the exhaust outflow direction. When the amount of condensate increases, the condensate is sequentially arranged in a line. Condensed water can be discharged from the small holes 8 and 9 one after another. That is, even if the condensed water increases, the condensed water can be discharged from the small holes 8 and 9 arranged in one example, and as a result, the drainage can be greatly improved.

  The small hole 8 formed in the inner tube 6 is preferably a circular hole (Φ5) having a diameter of about 5 mm to a circular hole (Φ1) having a diameter of about 1 mm. When the hole diameter is less than Φ1, it is difficult to discharge condensed water, and when the hole diameter exceeds Φ5, the amount of air leakage increases. On the other hand, the small holes 9 formed in the outer tube 4 are preferably 3 mm or less in diameter. When the hole diameter of the small hole 9 exceeds Φ3, sound in the pipe is liable to leak, and airflow generation sound when air is discharged from the small hole 9 to the outside of the pipe becomes high.

  In addition, it is more advantageous in terms of generating airflow noise that a plurality of small holes 9 are formed than a single large hole 9. In addition, it is preferable that the small holes 8 and 9 are opened at the bottom portion in the pipe circumferential direction. However, when the exhaust device 1 is used in common for each vehicle type, the lowest position in terms of coordinates from the layout. You may open the hole in the vehicle common use range of the position to come.

  And in the tube member 3A made into this double tube structure, as shown in FIG. 2, the muffling member 10 is provided in the space part 5 of the outer tube | pipe 4 and the inner tube | pipe 6. As shown in FIG. As shown in FIG. 4, the sound deadening member 10 is formed as an annular ring, and is attached to the outer peripheral surface of the inner tube 6. The silencing member 10 is sized so as to form at least a gap for allowing condensed water to pass through the outer tube 4, and is provided at two predetermined positions in the longitudinal direction of the inner tube 6. Further, the position where the muffler member 10 is formed is laid out in accordance with the frequency band to be muffled.

  Thus, if the space part 5 of the outer pipe 4 and the inner pipe 6 is partitioned by the sound deadening member 10, the inside of the space part 5 also has a sound deadening structure, and the sound leaked into the space part 5 is silenced except for particularly low frequencies. As a result, since the sound discharged from the outer tube 4 is a small sound, the influence of noise on the surroundings can be reduced.

  Further, by providing the sound deadening member 10 in the space portion 5, the sound deadening member 10 increases the mechanical strength of the double pipe structure portion, and prevents the double pipe structure portion from being crushed by an external force. Can do.

[Condensate drainage]
In the exhaust device 1 of the fuel cell vehicle configured as described above, the condensed water that has flowed into the tube member 3 flows from the inlet of the tube member 3A having a double tube structure, as indicated by the arrow in FIG. After entering the inner tube 6, it flows into the space 5 formed by the outer tube 4 and the inner tube 6 from the small hole 8 formed in the inner tube 6.

  At this time, the condensate is reliably discharged (drained) from the small holes 8 even when a large amount of the condensate is generated, since a plurality of the small holes 8 are formed at a predetermined interval in a row in the exhaust outflow direction. .

  The condensed water that has flowed into the space portion 5 flows through the bottom portion of the outer tube 4 and flows through the gap between the silencer 10 and the outer tube 4 and flows out in the exhaust outflow direction, and is formed in the outer tube 4. It is discharged from the small hole 9 to the outside of the pipe.

  Similarly to the inner pipe 6, the outer pipe 4 has a plurality of small holes 9 formed at a predetermined interval in a row in the exhaust outflow direction. Therefore, the condensed water flowing into the space portion 5 from the small holes 9 is The small hole 9 is surely discharged.

  As described above, according to the exhaust device of the present embodiment, the condensed water can be discharged at the front portion of the muffler 2, so that it is possible to prevent the condensed water from flowing into the muffler 2. Therefore, even when a large amount of condensed water is generated, the condensed water will not be contained in the sound absorbing material of the muffler 2, so that the sound absorbing function can be maintained without deterioration of the performance of the sound absorbing material.

  Further, according to the exhaust device of the present embodiment, the condensed water is not stored in the muffler 2, so there is no deterioration in the silencing performance due to icing and the generation of abnormal noise in the muffler 2 in cold regions, and further, the volume of the condensed water Cracks of the muffler 2 due to expansion can be prevented.

  Moreover, according to the exhaust apparatus of this Embodiment, since condensed water does not penetrate | invade into a sound absorption material, the corrosion inside the said muffler 2 by this condensed water collecting in the muffler 2 can be prevented.

[Other embodiments]
In the above-described embodiment, a part of the tube member 3 has a double-pipe structure. However, except for the weight and cost, the entire tube member 3 is formed in consideration of further improvement in drainage and noise reduction. A double tube structure may be used. In this case, although the weight increases, the condensed water can be discharged more reliably in front of the muffler 2 and the exhaust noise can be reduced.

  Further, in the present embodiment, the condensed water does not normally flow into the muffler 2, but if it flows, in order to prevent the condensed water from accumulating in the muffler 2, A drainage hole for discharging condensed water to the shell or the end plate may be formed. The design of the drainage is preferably controlled so that 4% or more of condensed water is not stored in the sound absorbing material so that the sound absorbing performance of the sound absorbing material does not deteriorate.

It is a figure which shows this Embodiment, and is the whole perspective view of the exhaust apparatus for fuel cell vehicles. It is a figure which shows this Embodiment, and is a principal part expanded sectional view of the tube member of a double pipe structure. It is a figure which shows this Embodiment, (a) is a principal part expansion perspective view which partially fractures and shows the inner tube in which the small hole was formed, (b) is a part of the inner tube in which the small hole was formed It is a principal part enlarged plan view broken and shown. It is a figure which shows this Embodiment, and is a perspective view of the inner pipe | tube with which the silencing member was attached. It is a principal part expanded sectional view of the conventional silencer. It is a side view which shows a conventional exhaust silencer partially broken. It is an expanded sectional view of the conventional exhaust double pipe.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Exhaust device 2 ... Muffler 3 ... Tube member 4 ... Outer tube 5 ... Space part 6 ... Inner tube 8, 9 ... Small hole 10 ... Silencer member

Claims (4)

In an exhaust device (1) for a fuel cell vehicle, comprising a muffler (2) that silences an exhaust sound, and a tube member (3) connected in front of the muffler (2).
At least a part (3A) of the tube member (3) includes an outer tube (4) and an inner tube (6) provided inside the outer tube (4) with a predetermined space (5). And a small hole (8, 9) for discharging at least one condensed water in the outer pipe (4) and the inner pipe (6). Exhaust device for battery car. An exhaust system (1) for a fuel cell vehicle according to claim 1,
A small hole (8) formed in the inner pipe (6) is provided on the upstream side in which the exhaust flows in the double pipe structure portion (3A), and a small hole (9) formed in the outer pipe (4). An exhaust device for a fuel cell vehicle, wherein the exhaust device is provided downstream of the exhaust. An exhaust system (1) for a fuel cell vehicle according to claim 1 or 2,
A plurality of small holes (8, 9) formed in the outer pipe (4) and the inner pipe (6) are formed, and the plurality of small holes (8, 9) are arranged at predetermined intervals along the exhaust outflow direction. An exhaust system for a fuel cell vehicle characterized by being arranged in a line. An exhaust device (1) for a fuel cell vehicle according to any one of claims 1 to 3,
An exhaust device for a fuel cell vehicle, wherein a sound deadening member (10) is provided in the space (5) between the outer tube (4) and the inner tube (6).

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