Fuel Cell System and Gas Leak Determination Method for Fuel Cell System

• US 20070207355A1
• Filed: 09/15/2005
• Published: 09/06/2007
• Est. Priority Date: 09/16/2004
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Yoshida, Naohiro
• Granted Patent: US 8,216,729 B2
• Time in Patent Office: Days
• US Class Current: 429/444
• CPC Class Codes: H01M 16/003 of fuel cells with other electrochemical devices, e.g. capacitors, electrolysers
• CPC Class Codes: H01M 8/04097 with recycling of the reactants H01M8/04119, H01M8/04104 take precedence
• CPC Class Codes: H01M 8/04225 during start-up
• CPC Class Codes: H01M 8/04228 during shut-down
• CPC Class Codes: H01M 8/04231 Purging of the reactants
• CPC Class Codes: H01M 8/04388 of anode reactants at the inlet or inside the fuel cell
• CPC Class Codes: H01M 8/04402 of anode exhausts
• CPC Class Codes: H01M 8/0444 Concentration; Density H01M8/04492 takes precedence
• CPC Class Codes: H01M 8/04664 Failure or abnormal function
• CPC Class Codes: H01M 8/04679 of fuel cell stacks
• CPC Class Codes: H01M 8/04753 of fuel cell reactants
• CPC Class Codes: H01M 8/04761 of fuel cell exhausts
• CPC Class Codes: H01M 8/0491 of fuel cell stacks
• CPC Class Codes: H01M 8/0494 of fuel cell stacks
• CPC Class Codes: H01M 8/04947 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/0662 Treatment of gaseous reactants or gaseous residues, e.g. cleaning
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A fuel cell system (10) of the present invention comprises determination means (50) for consuming a fuel gas present at a gas leak detection portion of a fuel gas supply system (31, 32) through the power generation of a fuel cell (20), and performing a gas leak determination on the basis of a pressure decrease margin of the fuel gas present at the gas leak detection portion, and comprises discharge means (H51) for reducing the pressure at the gas leak detection portion by purging the fuel gas present at the gas leak detection portion to the outside of the fuel gas supply system (31, 32). By not only consuming the fuel gas present at the gas leak detection portion through power generation, but also purging the fuel gas to the outside of the fuel gas supply system, the pressure at the gas leak detection portion can be brought close to a target pressure within a short time period, and the gas leak determination can be performed in a short period of time and with a high level of precision.

Claims

1. A fuel cell system comprising determination means for consuming a fuel gas present at a gas leak detection portion of a fuel gas supply system at an anode of a fuel cell, and performing a gas leak determination on the basis of a pressure variation state of said fuel gas present at said gas leak detection portion, comprising discharge means for reducing a pressure at said gas leak detection portion by purging said fuel gas present at said gas leak detection portion to the outside of said fuel gas supply system before performing said gas leak determination.

2. The fuel cell system according to claim 1, wherein when said pressure at said gas leak detection portion falls below a target pressure due to purging of said fuel gas, said discharge means restrict purging of said fuel gas.

3. The fuel cell system according to claim 1, wherein said discharge means vary a purge amount of said fuel gas present at said gas leak detection portion in accordance with a consumption amount of said fuel gas.

4. The fuel cell system according to claim 1, further comprising control means for varying a generated current of said fuel cell in accordance with said consumption amount of said fuel gas present at said gas leak detection portion.

5. The fuel cell system according to claim 1, further comprising storage means for storing power generated by said fuel cell,

wherein said discharge means vary said fuel gas purge amount in accordance with a charge amount of said storage means.

6. The fuel cell system according to claim 1, further comprising:

oxidizing gas supply means for supplying an oxidizing gas to a cathode of said fuel cell; and

a diluter for mixing and diluting a cathode off-gas discharged from said fuel cell and said fuel gas purged by said discharge means,

wherein said oxidizing gas supply means modify an oxidizing gas supply amount in accordance with said purge amount of said fuel gas purged from said discharge means.

7. The fuel cell system according to claim 1, further comprising a fuel gas sensor for detecting a fuel gas leak,

wherein said fuel gas purge amount purged each time from said discharge means is within a leak detection threshold range of said fuel gas sensor.

8. The fuel cell system according to claim 1, wherein said gas leak detection portion is a substantially sealed space formed by closing a valve disposed in said fuel gas supply system, and said determination means perform said gas leak determination after said valve is closed and a time required to stabilize the pressure in said substantially sealed space has elapsed.

9. The fuel cell system according to claim 1, wherein said discharge means are a purge valve disposed in an anode off-gas flow passage for discharging hydrogen off-gas discharged from said fuel cell to the outside of said system.

10. A gas leak determination method for a fuel cell system, in which a fuel gas present at a gas leak detection portion of a fuel gas supply system is consumed at an anode of a fuel cell, and a gas leak determination is performed on the basis of a pressure variation state of said fuel gas present at said gas leak detection portion, comprising the step of reducing a pressure at said gas leak detection portion by purging said fuel gas present at said gas leak detection portion to the outside of said fuel gas supply system before performing said gas leak determination.

11. The gas leak determination method for a fuel cell system according to claim 10, wherein said pressure at said gas leak detection portion falls below a target pressure due to purging of said fuel gas, purging of said fuel gas is restricted.

12. The gas leak determination method for a fuel cell system according to claim 10 wherein a purge amount of said fuel gas present at said gas leak detection portion is varied in accordance with a consumption amount of said fuel gas.