JP5111126B2 - Muffler for fuel cell car - Google Patents

Description

  The present invention relates to a silencer that silences exhaust gas discharged from a fuel cell mounted on a fuel cell vehicle.

  In a fuel cell automobile that runs by driving a drive motor with electricity generated by a fuel cell mounted on a vehicle, hydrogen gas as a fuel gas or air as an oxidant gas is supplied to the fuel cell to generate power, and the fuel Excess air supplied to the battery is discharged outside the vehicle as exhaust gas. In order to reduce the noise when the exhaust gas is discharged outside the vehicle, a silencer is installed in the exhaust gas passage in the fuel cell vehicle.

2. Description of the Related Art Conventionally, a silencer installed in an exhaust gas passage of a fuel cell vehicle has an expansion chamber formed between the cylinder and the housing by installing a cylinder serving as an exhaust gas passage through a sealed box-shaped housing. The tube is filled with a sound absorbing material such as glass wool, and the cylindrical body is provided with a number of small holes that open into the expansion chamber (see, for example, Patent Documents 1 and 2). In this silencer, when exhaust gas is caused to flow through the cylinder, the exhaust gas flows into the expansion chamber from the small hole of the cylinder, and the acoustic energy is attenuated and silenced by friction between the sound absorbing material and the sound wave in the expansion chamber.
JP 2007-64188 A JP 2004-39462 A

  However, since the silencer of the conventional fuel cell vehicle is silenced by the sound energy attenuating action of the sound absorbing material, a considerably large capacity sound absorbing material is required to obtain the desired sound deadening effect, and the expansion chamber is enlarged. I had to do it. This is disadvantageous for a fuel cell vehicle having a limited mounting space, and there has been a demand for a smaller silencer.

  Accordingly, the present invention provides a small silencer that is excellent in mountability to a fuel cell vehicle.

In the silencer of the fuel cell vehicle according to the present invention, the following means are adopted in order to solve the above problems.
The invention according to claim 1 is an exhaust gas discharged from the fuel cell of a fuel cell vehicle that runs by driving a drive motor with electricity generated by a fuel cell (for example, a fuel cell 1 in an embodiment described later) mounted on a vehicle. A silencer that silences the sound of gas (for example, a silencer 50 in an embodiment to be described later), and provided in the middle of an exhaust gas passage (for example, an exhaust gas passage 35 in an embodiment to be described later) through which the exhaust gas flows. A cylindrical silencing chamber (for example, a silencing chamber 56 in an embodiment described later), an introduction pipe for introducing the exhaust gas into the silencing chamber (for example, an introduction pipe 51 in an embodiment described later), and the silencing chamber discharge pipe for discharging the exhaust gas from (e.g., exhaust pipe 52 in the embodiment) and a, the muffling chamber, the common bottom surface and the inlet and the discharge tube, and Surface has expanded to deflect in at least vertically upwardly from said inlet pipe and said discharge pipe, into the muffling chamber is smaller small passage opening area which is formed parallel to the axis of the digestion sound chamber (e.g. The silencer of the fuel cell vehicle is characterized in that a rectifying member (for example, a rectifier 57 in an embodiment described later) having a large number of small passages 58 in the embodiment described later is provided without a gap .
The exhaust gas discharged from the fuel cell has no pulsation and can be regarded as almost a steady flow, and the exhaust sound of the exhaust gas of the fuel cell 1 is mostly airflow sound due to turbulent flow, and the airflow sound is reduced by rectification. can do. Here, the small passage of the rectifying member has a rectifying action, and the exhaust gas is rectified by passing the exhaust gas through the small passage, so that the flow noise of the exhaust gas can be reduced.

In addition , even if water accumulates in the small passage in the lower part of the muffler chamber and freezes and closes, the small passage in the upper part of the muffler room does not collect water and does not freeze and is not blocked. In this portion, a sufficient exhaust gas passage can be secured.

  According to the first aspect of the present invention, it is possible to reduce and muffle the sound of the exhaust gas discharged from the fuel cell by the rectifying action of the small passage. Since the silencer does not require an expansion chamber or a sound absorbing material, the silencer can be reduced in size.

Further, even frozen water even under side of the portion of the muffler chamber, since the passage of exhaust gas in the portion of the upper side of the muffler chamber can be sufficiently secured, hardly exhaust gas to flow up the back pressure Thus, the power generation amount of the fuel cell is reduced, and the exhaust gas passage is not blocked and the fuel cell is not disabled to generate power, and a sufficient power generation amount can be ensured.

Embodiments of a silencer for a fuel cell vehicle according to the present invention will be described below with reference to the drawings of FIGS.
The fuel cell vehicle according to the embodiment includes a fuel cell and a battery for charging electricity generated by the fuel cell, and a fuel that travels by supplying electricity to the drive motor directly or via the battery. It is a battery car. A capacitor may be used instead of the battery.

With reference to FIG. 5, a schematic configuration of a fuel cell system mounted on a fuel cell vehicle will be described.
The fuel cell 1 is a type that obtains electricity by chemically reacting a reaction gas. For example, a membrane electrode structure in which a solid polymer electrolyte membrane made of a solid polymer ion exchange membrane or the like is sandwiched between an anode electrode and a cathode electrode from both sides. And a plurality of cells each having an anode gas flow path 3 and a cathode gas flow path 5 are stacked on both sides of the membrane electrode structure. Hydrogen gas as an anode gas is supplied to the anode gas flow path 3. Then, when oxygen-containing air is supplied to the cathode gas flow path 5 as the cathode gas, hydrogen ions generated by the catalytic reaction at the anode electrode move to the cathode electrode through the solid polymer electrolyte membrane, and the cathode electrode It generates electricity by causing an electrochemical reaction with oxygen to produce water. In FIG. 1, the anode gas channel 3 and the cathode gas channel 5 of a single cell are shown as representatives.

  The cathode gas (air) is pressurized to a predetermined pressure by a compressor 7 such as a supercharger, and supplied to the cathode gas channel 5 of the fuel cell 1 through the cathode gas supply channel 9 and the humidifier 11. After the cathode gas supplied to the fuel cell 1 is used for power generation, it is discharged from the fuel cell 1 together with the generated water on the cathode side into the cathode offgas flow path 13 as cathode offgas (exhaust gas), and the humidifier 11 and the back pressure valve 15. And is discharged to the diluter 17. The humidifier 11 includes, for example, a water permeable membrane. When the cathode gas and the cathode off gas are circulated with the water permeable membrane interposed therebetween, moisture contained in the cathode off gas permeates the water permeable membrane and becomes cathode. It moves to gas and the cathode gas is humidified.

  On the other hand, the anode gas (hydrogen gas) supplied from the hydrogen tank 21 is supplied to the anode gas passage 3 of the fuel cell 1 through the anode gas supply passage 23, the shutoff valve 25, and the ejector 27. The unreacted anode gas that has not been consumed is discharged from the fuel cell 1 as an anode off-gas, sucked into the ejector 27 through the anode off-gas flow path 29, and merged with the fresh anode gas supplied from the hydrogen tank 21. Then, the fuel cell 1 is supplied again and circulated.

  A control device (not shown) drives the air compressor 7 according to the output required for the fuel cell 1 to supply a predetermined amount of air to the fuel cell 1 and controls the shut-off valve 25 from the hydrogen tank 21. A fixed amount of hydrogen gas is supplied to the fuel cell 1. Further, the control device controls the back pressure valve 15 to adjust the air supply pressure to the fuel cell 1 to a pressure corresponding to the required output of the fuel cell 1.

  An anode offgas discharge channel 33 having a discharge valve 31 branches off from the anode offgas channel 29. The discharge valve 31 is normally closed when the fuel cell 1 generates power, and opens when a predetermined condition is satisfied, and discharges the anode off-gas to the diluter 17 via the anode off-gas discharge passage 33. The control device controls the discharge valve 31 to adjust the discharge of the anode off gas.

  In the diluter 17, the anode offgas flowing in through the anode offgas discharge channel 33 and the cathode offgas flowing in through the cathode offgas channel 13 are mixed to dilute the anode offgas. This mixed gas is discharged from the diluter 17 to the atmosphere as an exhaust gas through the exhaust gas passage 35.

  A silencer (silencer) 50 for reducing exhaust gas exhaust noise and a hydrogen gas detector 39 for detecting hydrogen gas in the exhaust gas are installed in the middle of the exhaust gas passage 35. The hydrogen gas detector 39 checks that hydrogen gas having a predetermined concentration or more does not leak into the exhaust gas.

  As shown in FIGS. 1 to 3, the silencer 50 includes a small-diameter cylindrical introduction pipe 51 and a discharge pipe 52, a cylindrical silencer pipe 53 having a larger diameter than the introduction pipe 51 and the discharge pipe 52, and an introduction pipe 51. And a tapered cylindrical diameter-expanding tube 54 that connects the silencer tube 53, and a tapered cylindrical diameter-reduced tube 55 that connects the silencer tube 53 and the discharge tube 52. As shown in FIGS. 1 and 2, the introduction pipe 51, the discharge pipe 52, the muffler pipe 53, the diameter expansion pipe 54, and the diameter reduction pipe 55 have a common lower surface.

  In this embodiment, the introduction pipe 51 and the discharge pipe 52 have the same diameter. The expanded pipe 54 has a circular cross section at any position in the longitudinal direction, and is gradually expanded from the small diameter introduction pipe 51 to the large diameter muffler pipe 53. The reduced diameter tube 55 also has a circular cross section at any position in the longitudinal direction, and is gradually reduced in cross section from the large diameter muffler tube 53 to the small diameter discharge tube 52. The interior of the muffler tube 53 is a muffler chamber 56. That is, the muffler chamber 56 has a common lower surface with the introduction tube 51 and the discharge tube 52, and the cross section is at least vertically upward from the introduction tube 51 and the discharge tube 52. It is formed to expand so as to be displaced.

  The introduction pipe 51 is connected to the upstream side of the exhaust gas flow path 35 and introduces the exhaust gas discharged from the diluter 17 into the sound deadening chamber 56. The exhaust pipe 52 is connected to the downstream side of the exhaust gas flow path 35 and exhausts the exhaust gas flowing through the muffler chamber 56.

  A rectifier (rectifying member) 57 is provided in the muffler chamber 56 without a gap. The rectifier 57 is configured to include a plurality of small passages 58 having a square cross section with a very small opening area and extending linearly in parallel with the axis of the muffler tube 53, and has a so-called honeycomb shape. The opening area Sa of the rectifier 57 is set to be twice or more than the opening area Si of the introduction pipe 51 and the discharge pipe 52.

In the silencer 50 configured as described above, the cathode off-gas and anode off-gas discharged from the fuel cell 1 are discharged to the exhaust gas passage 35 via the diluter 17 and from the exhaust gas passage 35 via the introduction pipe 51. Introduced into the silencer 50.
As shown in FIG. 1, the exhaust gas introduced from the introduction pipe 51 is introduced into the sound deadening chamber 56 through the diameter expansion pipe 54, and is disposed on the lower side in the rectifier 57 installed in the sound deadening room 56. The gas is discharged to the reduced diameter pipe 55 through the small passage 58, further flows through the discharge pipe 52, and is discharged to the downstream side of the exhaust gas flow path 35. In addition, since the moisture contained in the exhaust gas can also pass through the small passage 58 disposed on the lower side, it is discharged from the discharge pipe 52 together with the exhaust gas.

  Here, the way the exhaust gas flows in the fuel cell 1 is substantially determined by the operating state of the compressor 7 and the opening of the back pressure valve 15. The compressor 7 has a slight change in the rotational speed depending on the required output of the fuel cell 1, but the change is small. Further, the opening of the back pressure valve 15 is also adjusted by the required output of the fuel cell 1, whereby the pressure of the exhaust gas also changes, but the amount of change is small and the change speed is also slow. That is, the exhaust gas of the fuel cell 1 has no pulsation and can be regarded as a steady flow.

Due to the nature of the exhaust gas flow of the fuel cell 1, the exhaust sound of the exhaust gas of the fuel cell 1 is mostly airflow sound due to turbulent flow, and the airflow sound can be reduced by rectification. The small passage 58 of the rectifier 57 of the silencer 50 has a rectifying action, and the exhaust gas is rectified by passing through the small passage 58, so that the flow sound of the exhaust gas can be silenced.
By the way, in the case of an internal combustion engine, there is a pulsating wave accompanying explosion, and an expansion chamber and a sound absorbing material are necessary to silence the explosion sound (pulsating wave), and it is silenced just by rectifying the flow of exhaust gas I can't.

  By the way, in this silencer 50, a rectifier 57 is provided in order to obtain a rectifying action. However, since the small passage 58 of the rectifier 57 has a small opening area, when the fuel cell 1 is stopped, the water droplets in the exhaust gas can be reduced. It is easy to collect in the small passage 58 arranged near. Further, when the fuel cell 1 is stopped in a low temperature environment, the moisture of the exhaust gas in the silencer 50 may be condensed into water droplets, which may accumulate in the small passage 58 disposed on the lower side. In this way, when the water is accumulated in the small passage 58 arranged below, the temperature of the rectifier 57 is small because the small passage 58 of the rectifier 57 has a small diameter, the contact area with water is large, and the cooling area is large. The accumulated water tends to freeze, and in particular, it begins to freeze from the side close to the lower outer peripheral surface where the temperature of the muffler tube 53 tends to be low, and closes the lower small passage 58.

  However, in this silencer 50, the cross section of the muffler chamber 56 is expanded above the cross sections of the introduction pipe 51 and the discharge pipe 52, and therefore, as shown in FIG. Even if the small passage 58 of the portion is closed due to freezing, water does not accumulate in the upper portion of the small passage 58 in the rectifier 57, so that it opens without being frozen and closed. It can be distributed. Also in this case, the exhaust gas flows through the upper small passage 58, so that the exhaust gas is rectified and the airflow noise is silenced.

  Therefore, even if water freezes in the lower part of the muffler chamber 56, a sufficient exhaust gas passage can be secured in the upper part of the muffler chamber 56, so that the back pressure increases and the exhaust gas is exhausted. It is possible to prevent the gas from flowing and reduce the power generation amount of the fuel cell 1 or to prevent the fuel cell 1 from being unable to generate power due to the exhaust gas passage being blocked, thereby securing a sufficient power generation amount. it can.

  Since the silencer 50 does not require an expansion chamber or a sound absorbing material unlike the conventional silencer, even if the opening area Sa of the rectifier 57 is set to be twice the opening area Si of the introduction pipe 51 and the discharge pipe 52, When compared with the case where the same silencing performance is obtained, it can be made smaller than the conventional one. For example, a silencer having a conventional structure including an expansion chamber and a sound absorbing material required a volume of 6 liters, but the silencer 50 of the embodiment can obtain an equivalent noise reduction performance with a volume of 2 liters or less.

  If the area where the fuel cell vehicle is used does not become a freezing environment, it is not necessary to consider the blockage of the passage due to water freezing in the small passage 58 of the rectifier 57. Therefore, as shown in FIG. The opening area Sa may be the same as the opening area Si of the introduction pipe 51 and the discharge pipe 52.

[Other Examples]
The present invention is not limited to the embodiment described above.
For example, in the above-described embodiment, the sound deadening chamber is cylindrical, but the cross-sectional shape is not particularly limited. Further, the cross-sectional shape of the passage of the rectifying member is not limited to a square, and may be a regular hexagon, for example.

It is sectional drawing in the Example of the silencer which concerns on this invention. It is sectional drawing which shows the flow of exhaust gas when water freezes in the inside lower part of the silencer in the said Example. It is a perspective view of the silencer in the said Example. It is sectional drawing in the other Example of the silencer which concerns on this invention. It is a block diagram of the fuel cell system in the fuel cell vehicle carrying the silencer according to the present invention.

Explanation of symbols

1 Fuel cell 35 Exhaust gas passage (exhaust gas passage)
50 Silencer
51 Introducing pipe 52 Discharging pipe 56 Silence chamber 57 Rectifier
58 Small passage

Claims (1)

A muffler that muffles the sound of exhaust gas discharged from the fuel cell of a fuel cell vehicle that runs by driving a drive motor with electricity generated by a fuel cell mounted on a vehicle,
Provided in the middle of the exhaust gas passage through which the exhaust gas flows, a cylindrical silencer chamber, an introduction pipe for introducing the exhaust gas into the silencer chamber, and a discharge pipe for discharging the exhaust gas from the silencer chamber Prepared,
The silencer chamber has a lower surface in common with the introduction pipe and the discharge pipe, and is expanded so that a cross section is displaced at least vertically upward from the introduction pipe and the discharge pipe,
A muffler for a fuel cell vehicle, wherein the muffler chamber is provided with a rectifying member having a large number of small passages having a small opening area formed in parallel with the axis of the muffler chamber without any gaps .

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