Fuel cell system

Patent metadata

Field	Value
Publication number	US-9397353-B2
Application number	US-201114235497-A
Country	US
Kind code	B2
Filing date	Sep 15, 2011
Priority date	Sep 15, 2011
Publication date	Jul 19, 2016
Grant date	Jul 19, 2016

Abstract

The object is to suppress degradation of the durability of an electrolyte membrane caused by deformation by expansion and contraction of the electrolyte membrane. A controller 150 calculates a humidity P of an electrolyte membrane 112 based on a cell resistance value (step S 11 ) and determines whether the humidity P of the electrolyte membrane 112 is less than a humidity threshold A (step S 12 ). When the humidity P is less than the humidity threshold A, the controller 150 determines that a dimensional change rate of the electrolyte membrane is not greater than a predetermined value and performs a process of increasing the humidity of the electrolyte membrane 112 (step S 13 ). The predetermined value is a dimensional change rate that is unlikely to have damage by drying stress. This enables the electrolyte membrane 112 to be humidified before the electrolyte membrane 112 is excessively dried and thereby suppresses tensile stress from being applied to the electrolyte membrane 112 by drying of the electrolyte membrane 112 . Accordingly this suppresses cracking and thinning of the electrolyte membrane 112 and improves the durability of the electrolyte membrane 112.

First claim

The invention claimed is:

1. A fuel cell system comprising:
a fuel cell configured to have a solid polymer electrolyte membrane;
a controller configured to control the fuel cell; and
an acquirer configured to obtain information on humidity of the electrolyte membrane, wherein
when the humidity of the electrolyte membrane is equal to or less than a threshold value for a predetermined time, the controller is programmed to control a wet state of the electrolyte membrane such that a dimensional change rate of the electrolyte membrane, which is a change rate in area in a planar direction of the electrolyte membrane accompanied with expansion or contraction of the electrolyte membrane, is equal to or greater than a predetermined value which is greater than a dimensional change rate corresponding to a state in which the electrolyte membrane is damaged by tensile stress applied to the electrolyte membrane by drying of the electrolyte membrane,
the threshold value is specified by a humidity range of the electrolyte membrane when the dimensional change rate of the electrolyte membrane is −1.5% to 0%, and
the predetermined time is a predetermined time period from a time when the dimensional change rate of the electrolyte membrane becomes equal to 0% to a time when the dimensional change rate of the electrolyte membrane becomes less than 0%.

2. The fuel cell system according to claim 1 , wherein
the predetermined value is 0%.

3. The fuel cell system according to claim 2 , wherein
the controller is configured to control the wet state of the electrolyte membrane, such that the dimensional change rate is equal to or greater than the predetermined value and equal to or less than +9.0%.

4. The fuel cell system according to claim 1 , wherein
the predetermined value is −1.5%.

5. The fuel cell system according to claim 1 , wherein
the predetermined value is specified by the dimensional change rate within a predetermined range including the dimensional change rate of the electrolyte membrane equal to 0%.

6. The fuel cell system according to claim 1 , wherein
the threshold value differs by temperature,
the fuel cell system further comprising:
a temperature detector configured to detect a temperature of the electrolyte membrane, wherein
the controller is configured to change the threshold value based on the temperature of the electrolyte membrane.

7. The fuel cell system according to claim 1 , further comprising:
a map showing a relationship between a time required for a change in humidity of the electrolyte membrane and a time period from a time when the humidity becomes equal to or less than the threshold value to a time when tensile stress starts acting on the electrolyte membrane, wherein
the predetermined time is specified based on at least one of a change in humidity of the electrolyte membrane per unit time and a humidity of the electrolyte membrane after the change in humidity and the map.

8. The fuel cell system according to claim 1 , wherein
the controller is configured to control the wet state of the electrolyte membrane by controlling parameters relating to power generation performance.

9. A fuel cell system comprising:
a fuel cell configured to have a solid polymer electrolyte membrane;
a controller configured to control the fuel cell;
a voltage detector configured to detect voltage of the fuel cell; and
a temperature detector configured to detect a temperature of the electrolyte membrane, wherein
when the voltage is equal to or greater than a threshold value, the controller is programmed to control a wet state of the electrolyte membrane such that a dimensional change rate of the electrolyte membrane, which is a change rate in area in a planar direction of the electrolyte membrane accompanied with expansion or contraction of the electrolyte membrane is equal to or greater than a predetermined value which is greater than a dimensional change rate corresponding to a state in which the electrolyte membrane is damaged by tensile stress applied to the electrolyte membrane by drying of the electrolyte membrane,
the threshold value is a voltage of the fuel cell when the dimensional change rate of the electrolyte membrane is −1.5% to 0%, and
the controller is configured to change the threshold value based on the temperature of the electrolyte membrane such that the controller is configured to control the wet state of the electrolyte membrane based on the voltage detected by the voltage detector and the temperature detected by the temperature detector.

10. The fuel cell system according to claim 9 , wherein
the controller is configured to control the wet state of the electrolyte membrane by controlling parameters relating to power generation performance.

11. In a fuel cell system comprising an electrolyte membrane, a control method of controlling a wet state of the electrolyte membrane, the control method comprising:
obtaining a dimensional change rate, which is a change rate in area in a planar direction of the electrolyte membrane accompanied with expansion and contraction of the electrolyte membrane;
obtaining information on humidity of the electrolyte membrane; and
when the humidity of the electrolyte membrane is equal to or less than a threshold value for a predetermined time, controlling the wet state of the electrolyte membrane such that the dimensional change rate is equal to or greater than a predetermined value, the predetermined value being greater than a dimensional change rate corresponding to a state in which the electrolyte membrane is damaged by tensile stress applied to the electrolyte membrane by drying of the electrolyte membrane, wherein
the threshold value is specified by a humidity range of the electrolyte membrane when the dimensional change rate of the electrolyte membrane is −1.5% to +9%, and
the predetermined time is a predetermined time period from a time when the dimensional change rate of the electrolyte membrane becomes equal to 0% to a time when the dimensional change rate of the electrolyte membrane becomes less than 0%.

12. In a fuel cell system comprising an electrolyte membrane, a control method of controlling a wet state of the electrolyte membrane, the control method comprising:
obtaining a dimensional change rate, which is a change rate in area in a planar direction of the electrolyte membrane accompanied with expansion and contraction of the electrolyte membrane;
detecting voltage of the fuel cell;
detecting temperature of the electrolyte membrane;
changing a threshold value based on temperature of the electrolyte membrane, wherein the threshold value is a voltage of the fuel cell when the dimensional change rate of the electrolyte membrane is −1.5% to 0%; and
controlling the wet state of the electrolyte membrane when the voltage is equal to or greater than the threshold value such that the dimensional change rate is equal to or greater than a predetermined value, the predetermined value being greater than a dimensional change rate corresponding to a state in which the electrolyte membrane is damaged by tensile stress applied to the electrolyte membrane by drying of the electrolyte membrane.

Assignees

• Uchiyama Tomoaki
• Toyota Motor Co Ltd

Inventors

• Uchiyama Tomoaki

Classifications

• H01M8/04365 Primary

  of other components of a fuel cell or fuel cell stacks · CPC title

• H01M2008/1095

  Fuel cells with polymeric electrolytes · CPC title

• H01M8/04529

  of the electrolyte · CPC title

• H01M8/0485 Primary

  of the electrolyte · CPC title

• H01M8/04552

  of the individual fuel cell · CPC title