JP2005203261A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system having no possibility generating corrosion of a motor part when fuel cell off gas is circulated again. <P>SOLUTION: The fuel cell system has a compression means comprising a suction part 5 sucking off gas exhausted from a fuel cell 1, and the motor part 6 communicating with the suction part and housing a motor acting as a driving source when off gas sucked in the suction part is compressed, and also has a motor part pressing means 2 making the motor part in a higher pressure state than the suction part. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel cell system.

In the fuel cell system, in order to increase the fuel utilization efficiency, off-gas containing fuel hydrogen once supplied to the fuel cell and partially discharged without being reacted is recirculated to the fuel cell. In Patent Document 1, residual oxygen or residual hydrogen discharged from the fuel cell main body is returned to the oxygen / hydrogen supply line to the fuel cell main body using a circulation pump or a compressor, and a closed loop is assembled and circulated. A solid polymer electrolyte fuel cell system is disclosed. Patent Document 2 is cited as a technique for disclosing a related technique in this technical field.
JP-A-7-240220 JP2003-178882

  However, since the residual oxygen or residual hydrogen discharged from the fuel cell body contains moisture generated in the fuel cell, this moisture enters the motor part communicating with the fuel off-gas intake part of the circulation pump. Then, there existed a problem that corrosion of a motor part will generate | occur | produce.

  Accordingly, an object of the present invention is to provide a fuel cell system in which corrosion of the motor portion does not occur when the fuel cell off-gas is recirculated.

In order to solve the above problems, the present invention takes the following means. That is,
According to the first aspect of the present invention, there is provided a suction portion that sucks off gas discharged from the fuel cell, and a motor that is in communication with the suction portion and serves as a drive source when compressing the off gas sucked into the suction portion. A fuel cell system comprising compression means comprising a motor part to be housed, comprising a motor part pressurizing means for causing the motor part to be in a higher pressure state than the suction part.

  A second aspect of the present invention is the fuel cell system according to the first aspect, further comprising fuel gas storage means for storing the fuel gas supplied to the fuel cell at a high pressure, wherein the motor unit pressurizing means is a fuel gas storage means. A high pressure state is generated by filling the fuel gas stored in the means into the motor unit.

  According to a third aspect of the present invention, in the fuel cell system according to the second aspect of the present invention, the fuel cell system further includes a pressure regulating unit that regulates the fuel gas, and the pressure regulating unit is disposed between the fuel gas storage unit and the motor unit. It is characterized by that.

  According to the fuel cell system of the first aspect, the motor part can be brought into a higher pressure state than the suction part by the motor part pressurizing means. Therefore, it is possible to prevent the moisture contained in the off-gas sucked by the suction part from entering the motor part and to prevent the corrosion of the motor part due to the water penetration.

  According to the invention described in claim 2, since the high pressure state is generated by the fuel gas stored in the fuel gas storage means, there is an advantage that it is not necessary to add a new device to generate the high pressure state. .

  According to the third aspect of the present invention, since the pressure adjusting means is disposed between the motor unit and the fuel gas storage means, the pressure in the motor unit is kept substantially constant. Therefore, it is possible to prevent the motor unit from being damaged due to pressure changes in the motor unit.

(First embodiment)
FIG. 1 is a diagram schematically showing a fuel cell system according to a first embodiment of the present invention. The fuel cell system 10 according to the first embodiment includes a fuel cell 1, a compression means 2 for recirculating off-gas discharged from the fuel cell 1 to the fuel cell 1, and high-pressure fuel hydrogen gas supplied to the fuel cell 1. And a high-pressure hydrogen tank 3 stored in The compression means 2 includes a compression chamber 4, a suction chamber 5, and a motor chamber 6 arranged in this order. The suction chamber 5 is arranged on the upstream side (suction side) of the recirculation path of the compression chamber 4. The suction chamber 5 and the motor chamber 6 are partitioned by a partition wall 7. A compressor 4 a is disposed in the compression chamber 4. A motor 6 a is disposed in the motor chamber 6. The drive shaft 8 for transmitting the drive force generated by the motor 6a passes through the partition wall 7 from the motor chamber 6 and passes through the suction chamber 5, and is connected to the compressor 4a. A portion where the drive shaft 8 penetrates the partition wall 7 is maintained at a predetermined level of airtightness by an appropriate shaft seal or the like. A gas passage 11 is disposed from the exhaust port 1 a of the fuel cell 1 to the suction chamber 5. Gas passages 12 and 13 are disposed from the downstream side (discharge side) of the compression chamber 4 to the suction port 1 b of the fuel cell 1.

  On the other hand, a gas passage 14 is disposed from the gas outlet port 3 a of the high-pressure hydrogen tank 3 to the motor chamber 6. A gas passage 15 is led out from the motor chamber 6 and merged with the gas passage 13. In the motor chamber 6, the part into which the gas passage 14 is introduced and the part from which the gas passage 15 is led are arranged apart from each other. A regulator 9 is installed in the gas passage 15.

  In such a configuration, first, recirculation of off-gas discharged from the fuel cell 1 will be described. When the motor 6a is rotated, the rotational force is transmitted to the compressor 4a through the drive shaft 8, and the off-gas is compressed by the operation of the compressor 4a, and the fuel is again supplied through the gas passages 12 and 13. Off-gas is sent out to the suction port 1 b of the battery 1. At the same time, a negative pressure is generated in the suction chamber 5 disposed on the suction side of the compression chamber 4, and off-gas discharged from the exhaust port 1 a of the fuel cell 1 is introduced into the suction chamber 5 through the gas passage 11.

  On the other hand, the fuel hydrogen gas from the high-pressure hydrogen tank 3 is supplied to the fuel cell 1 as shown below. The high-pressure fuel hydrogen gas stored in the high-pressure hydrogen tank 3 enters the motor chamber 6 through the gas passage 14 by its own pressure when the gas outlet port 3a of the tank is opened. After filling the motor chamber 6, the motor chamber 6 reaches the gas passage 15, the regulator 9, and the gas passage 13. The gas is then combined with the off-gas recirculated through the gas passage 12 in the gas passage 13, led to the intake port 1 b of the fuel cell 1, and supplied as fuel hydrogen gas into the fuel cell 1 for use. .

In the above configuration, the pressure of the fuel hydrogen gas from the high pressure hydrogen tank 3 to the regulator 9 through the gas passage 14, the motor chamber 6, and the gas passage 15 is basically the same as the gas pressure V 1 of the high pressure hydrogen tank 3. Are identical. On the other hand, the gas pressure from the exhaust port 1a of the fuel cell 1 through the gas passage 11, the suction chamber 5, the compression chamber 4, the gas passage 12, and the gas passage 13 to the suction port 1b of the fuel cell 1 is mainly It is governed by the pressure V2 determined by the pressure generated by the compressor 4a, the exhaust pressure of the fuel cell 1 itself, and the like. And usually
V1 >> V2
Therefore, the pressure V1 in the motor chamber 6 is sufficiently higher than the pressure V2 in the suction chamber 5. As described above, since the drive shaft 8 of the motor 6a passes through the partition wall 7 separating the suction chamber 5 and the motor chamber 6, airtightness is maintained between the partition wall 7 and the drive shaft 8 by a shaft seal or the like. However, this airtightness is not always sufficient, and conventionally, there is a possibility that the off gas in the suction chamber 5 may enter the motor chamber 6. However, by adopting the above configuration, it is possible to prevent the off gas from entering the motor chamber 6 maintained at a high pressure with dry hydrogen from the suction chamber 5 side at a lower pressure. Therefore, it is possible to prevent the occurrence of defects such as corrosion of the motor due to moisture contained in the off gas. Moreover, since the high pressure state is generated by the stored fuel hydrogen gas, it is not necessary to provide a new pressure generating means.

  In addition, a regulator 9 is installed in the gas passage 15 so that the pressure of the fuel hydrogen gas is appropriately adjusted. Therefore, in the gas passage 13, the fuel hydrogen gas and the recirculated off gas merge. Thus, it is guided to the intake port 1b of the fuel cell 1 and the backflow of off-gas in the gas passage 12 is prevented.

  Further, since the fuel hydrogen gas discharged from the high-pressure hydrogen tank 3 and having a low temperature due to adiabatic expansion is circulated in the motor chamber 6, the motor 6a is thereby cooled. In the motor chamber 6, the portion where the gas passage 14 is introduced and the portion where the gas passage 15 is led are arranged apart from each other, so that the inside of the motor chamber 6 can be evenly cooled. Therefore, installation of a water cooling device, a cooling fin, or the like on the motor 6a can be omitted.

(Second Embodiment)
FIG. 2 is a diagram schematically showing a fuel cell system according to a second embodiment of the present invention. In the fuel cell system 20 of FIG. 2, when the same members as the fuel cell system 10 of the first embodiment are used, the same reference as FIG. 1 showing the fuel cell system 10 of the first embodiment. Reference numerals may be attached and descriptions thereof may be omitted. The same applies to the following drawings.

  The illustrated fuel cell system 20 is the fuel of the first embodiment in which the regulator 9 for adjusting the pressure of the fuel hydrogen gas is disposed in the gas passage 14, and the regulator 9 is disposed in the gas passage 15. Different from the battery system 10. The regulator 9 is prepared so that the pressure of the fuel hydrogen gas in the high-pressure hydrogen tank 3 supplied to the motor chamber 6 is slightly higher than the pressure of the off-gas in the suction chamber 5 in the recirculation path. By adopting such a configuration, as in the fuel cell system 10 of the first embodiment, off-gas enters the motor chamber 6 maintained at a high pressure by dry hydrogen from the suction chamber 5 side at a lower pressure. It is possible to prevent the occurrence of defects such as corrosion of the motor due to moisture contained in the off-gas. Further, since the fuel hydrogen gas having a low temperature is circulated in the motor chamber 6, the motor 6a is cooled by this, and the installation of the water cooling device, the cooling fin, etc. of the motor can be omitted.

  Further, in the fuel cell system 20 of the present embodiment, the fuel hydrogen gas supplied to the motor chamber 6 is depressurized from the high pressure state of the high pressure hydrogen tank 3 to a substantially constant pressure that is slightly higher than the pressure of the suction chamber 5 by the regulator 9. Therefore, the seal can be prevented from being damaged due to a pressure change and the seal being damaged due to the high pressure state of the seal. Therefore, a shaft seal 21 between the partition wall 7 that partitions the motor chamber 6 and the suction chamber 5 and the drive shaft 8 that penetrates the partition wall 7 from the motor chamber 6 toward the suction chamber 5 is used as an oil seal or lip that is normally used. It can be composed of a simple material such as a seal.

  FIG. 3 is a cross-sectional view showing an example of the shaft seal 21 provided in the partition wall 7 disposed between the motor chamber 6 and the suction chamber 5. In FIG. 3, a motor chamber 6 is shown in the center of the drawing, and a suction chamber 5 is arranged on the right side of the motor chamber 6. A partition wall 7 partitions the suction chamber 5 and the motor chamber 6. The motor 6a has a drive shaft 8 at the center of rotation. The drive shaft 8 is rotatably attached to the central portions of the motor chamber 6 and the suction chamber 5 via a bearing 22 attached to the housing side wall 26 of the motor chamber 6 and a bearing 23 attached to the holder portion 27 of the partition wall 7. ing. Further, the side shown on the right side of the drive shaft 8 is connected to a compressor 4a not shown in the figure. In the holder portion 27, the shaft seal 21 is disposed on the suction chamber side of the bearing 23. In the lower left part of the motor chamber 6 in the drawing, an inlet 24 for receiving dry fuel hydrogen gas from the high-pressure hydrogen tank 3 through the gas passage 14 is provided. On the other hand, in the upper right part of the motor chamber 6 in the drawing, there is provided a discharge port 25 for sending the fuel hydrogen gas introduced into the motor chamber 6 to the gas passage 15 side.

  In such a structure of the motor chamber 6 and the suction chamber 5, if there is an off-gas leak from the suction chamber 5 side to the motor chamber 6 side, it is the outer peripheral portion of the drive shaft 8 that penetrates the partition wall 7. From a site along the periphery. However, as described above, since the motor chamber 6 is maintained at a higher pressure than the suction chamber 5 by the fuel hydrogen gas, such a leak hardly occurs. Therefore, the shaft seal 21 may be constituted by a simple one such as an oil seal or a lip seal as shown.

  In the present invention, the type of the compressor is not particularly limited, and for example, a reciprocating, screw, scroll, turbo, or roots type compressor can be used. However, in the fuel cell system 50 according to the fifth embodiment, which will be described later, a Roots type is adopted as the compressor type.

(Third embodiment)
FIG. 4 is a diagram schematically showing a fuel cell system according to a third embodiment of the present invention. The illustrated fuel cell system 30 is different from the fuel cell system 20 according to the second embodiment in that a bypass passage 16 from the gas passage 14 to the gas passage 15 is provided and an orifice 17 is provided in the bypass passage 16. . In this fuel cell system 30, a part of the dry fuel hydrogen gas whose pressure has been lowered by the regulator 9 passes through the motor chamber 6, and the remaining fuel hydrogen gas passes directly through the bypass passage 16 and directly into the fuel cell. 1 is adopted. In this case, the presence or absence of an orifice may never be provided according to the required amount of fuel hydrogen gas passing through the motor chamber 6.

  Also in the fuel cell system 30 having such a configuration, similarly to the fuel cell systems 10 and 20 of the first and second embodiments, the suction at a lower pressure is introduced into the motor chamber 6 maintained at a high pressure by dry hydrogen. The intrusion of off-gas from the chamber 5 side is suppressed, and it becomes possible to prevent the occurrence of defects such as corrosion of the motor due to moisture contained in the off-gas. In addition, since the low temperature fuel hydrogen gas is circulated in the motor chamber 6, the motor 6a is thereby cooled, and the installation of a water cooling device, cooling fins, and the like of the motor 6a can be omitted. Further, as in the fuel cell system 20 of the second embodiment, the inside of the motor chamber 6 can be maintained at a moderately high pressure, so that the seal can be configured with a simple one.

(Fourth embodiment)
FIG. 5 is a diagram schematically showing a fuel cell system according to a fourth embodiment of the present invention. In the illustrated fuel cell system 40, the fuel hydrogen gas in the high-pressure hydrogen tank 3 is guided to the motor chamber 6 through the gas passage 14 while maintaining a high pressure, and the fuel hydrogen gas guided to the motor chamber 6 is used as it is. The fuel hydrogen gas in the motor chamber 6 is not supplied to the fuel cell 1 as in the fuel cell systems 10, 20, and 30 according to the first to third embodiments. The fuel hydrogen gas is reduced in pressure to a predetermined pressure by a regulator 9 provided in the bypass passage 16 through the bypass passage 16 and further supplied to the fuel cell 1 through the gas passage 13. On the other hand, regarding the recirculation of the off gas discharged from the fuel cell 1 in the fuel cell system 40, the fuel cell system 10, 20, and 30 according to the first to third embodiments described above and the like, The exhaust gas is supplied again to the intake port 1b of the fuel cell 1 through the exhaust port 1a, the gas passage 11, the suction chamber 5, the compression chamber 4, and the gas passages 12 and 13.

  In the fuel cell system 40 having such a configuration, the high-pressure fuel hydrogen gas is directly supplied to the motor chamber 6, so that a sufficient differential pressure with respect to the suction chamber 5 can be obtained, and the off-gas is surely introduced into the motor chamber 6. Intrusion can be prevented. Further, since a gas passage for guiding the fuel hydrogen gas in the motor chamber 6 to the fuel cell 1 is not required, the system can be simplified accordingly.

(Fifth embodiment)
FIG. 6 is a diagram schematically showing a fuel cell system according to a fifth embodiment of the present invention. The illustrated fuel cell system 50 has a first feature in that a roots compressor 51 is used as a compressor. The root compressor 51 is shown on the front side of FIG. 6, and the gear box 55 and the motor chamber 60 are arranged in that order on the back side. Each of the roots compressor 51, the gear box 55, and the motor chamber 60 is partitioned by a partition wall. The driving force of a motor (not shown) accommodated in the motor chamber 60 is converted into a biaxial driving force that rotates in different directions by a conversion device in the gear box 55, and the rotor 51 a of the roots compressor 51 is moved. Driving. Accordingly, one drive shaft is passed through the partition wall that partitions the motor chamber 60 and the gear box 55, and two drive shafts pass through the partition wall that partitions the gear box 55 and the roots compressor 51. . No seal is provided on the partition wall that partitions the motor chamber 60 and the gear box 55 through which one drive shaft passes. Further, a seal is provided on a partition wall that partitions the gear box 55 through which the two drive shafts pass and the roots compressor 51.

  A gas passage 11 is led from the exhaust port 1 a of the fuel cell 1 to the roots compressor 51. From the roots compressor 51, gas passages 12 and 13 are led to the intake port 1 b of the fuel cell 1. These form an off-gas recirculation path of the fuel cell 1. When the motor in the motor chamber 60 is rotated, the rotational force is transmitted to the gear box 55 via the drive shaft and converted into a biaxial rotational drive force. When the biaxial rotational driving force rotates the rotor 51 a of the roots compressor 51, the off gas is compressed, and the off gas is sent out again to the intake port 1 b of the fuel cell 1 through the gas passages 12 and 13. At the same time, a negative pressure is generated on the suction side of the roots compressor 51, and off-gas discharged from the exhaust port 1 a of the fuel cell 1 is introduced into the roots compressor 51 through the gas passage 11.

  On the other hand, the gas passage 14 is led from the high-pressure hydrogen tank 3 to the motor chamber 60. The high-pressure fuel hydrogen gas introduced into the motor chamber 60 easily enters the gear box 55. This is because no seal is provided between the motor chamber 60 and the gear box 55. Further, the high-pressure fuel hydrogen gas in the gear box 55 is adjusted to a predetermined pressure by the regulator 9 provided in the gas passage 15 and then merges with the recirculated off-gas through the gas passages 15 and 13. It is supplied from the intake port 1b to the fuel cell 1 and used as fuel gas.

  In the fuel cell system 50 having such a configuration, a gear box 55 is disposed between the roots compressor 51 and the motor chamber 60, so that moisture containing moisture from the roots compressor 51 enters the motor chamber 60. The gear box 55 is a structural buffer. This is the second feature of this embodiment. Moreover, the gear box 55 and the motor chamber 60 are filled with dry high-pressure fuel hydrogen gas, and the flow direction is directed from the motor chamber 60 toward the gear box 55, so that the motor from the roots compressor 51 is increasingly used. Infiltration of off-gas containing moisture into the chamber 60 is difficult.

  Further, the structure of the Roots compressor 51 itself has a check valve function, and even when the pressure on the exhaust port 1a side of the fuel cell 1 is reduced, the back flow of the off gas can be prevented. Therefore, since it is not necessary to provide a reverse support valve in the recirculation path, the structure of the fuel cell system can be simplified. Furthermore, by disposing the suction part of the roots compressor 51 on the lower side, it is possible to have the function of a gas-liquid separator. Also in the fuel cell system 50 of the present embodiment, the low-temperature fuel hydrogen gas is supplied to the motor chamber 60, so that the motor is cooled, and the installation of the motor water cooling device, cooling fins, etc. is omitted. Is possible.

  In each of the above embodiments, the anode side circulation has been described. However, the present invention is not limited to this, and the motor unit is also applied to the cathode side for gas recirculation at the cathode. It can also be configured to protect against moisture corrosion.

1 is a diagram showing a fuel cell system according to a first embodiment of the present invention. It is a figure which shows the fuel cell system concerning 2nd Embodiment of this invention. It is sectional drawing which shows an example of the seal | sticker provided in the partition arrange | positioned between the motor chamber and the suction chamber. It is a figure which shows the fuel cell system concerning 3rd Embodiment of this invention. It is a figure which shows the fuel cell system concerning 4th Embodiment of this invention. It is a figure which shows the fuel cell system concerning 5th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell 1a Exhaust port 1b Suction port 2 Compression means 3 High pressure hydrogen tank 3a Gas outlet port 4 Compression chamber 4a Compressor 5 Suction chamber 6 Motor chamber 6a Motor 7 Partition 8 Drive shaft 9 Regulator 10, 20, 30, 40, 50 Fuel cell system 11, 12, 13, 14, 15 Gas passage 16 Bypass passage 17 Orifice 21 Shaft seal 22, 23 Bearing 24 Suction port 25 Suction port 26 Housing side wall 27 Holder part 51 Roots compressor 51a Rotor 55 Gear box 60 Motor chamber

Claims (3)

A suction part for sucking off the gas discharged from the fuel cell; and a motor part that communicates with the suction part and accommodates a motor serving as a drive source when compressing the off gas sucked into the suction part. The fuel cell system further comprises a motor unit pressurizing unit that causes the motor unit to be in a higher pressure state than the suction unit. Fuel gas storage means for storing the fuel gas supplied to the fuel cell at a high pressure is provided, and the motor part pressurizing means fills the motor part with the fuel gas stored in the fuel gas storage means. The fuel cell system according to claim 1, wherein the high pressure state is generated by the operation. 3. The fuel cell system according to claim 2, further comprising pressure adjusting means for adjusting the fuel gas, wherein the pressure adjusting means is disposed between the fuel gas storage means and the motor unit.

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