Fuel cell system for a vehicle

Patent metadata

Field	Value
Publication number	US-11024860-B2
Application number	US-201815868393-A
Country	US
Kind code	B2
Filing date	Jan 11, 2018
Priority date	Jan 11, 2018
Publication date	Jun 1, 2021
Grant date	Jun 1, 2021

Abstract

A fuel cell system and a method of controlling the fuel cell system is provided. A fuel cell generates power, and a coolant system provides coolant flow through the stack. A controller is configured to, in response to at least one of an ambient temperature and a coolant temperature being below a threshold value after a vehicle shut down command or event, command the coolant system to circulate coolant through the stack to reduce ice formation in the stack prior to commanding a purge of the fuel cell stack.

First claim

What is claimed is:

1. A method of controlling a vehicle fuel cell system comprising:
responsive to a vehicle shutdown event, shutting down a coolant system via a controller such that a pump does not operate and a coolant flow rate through a fuel cell stack is zero with coolant present in a central region of the fuel cell stack and outside the central region in the fuel cell stack;
after the vehicle shutdown event and while the pump is inoperative, monitoring an ambient temperature outside the fuel cell stack and a coolant temperature outside the central region; and
after a time delay following the vehicle shutdown event during which the pump is inoperative and coolant in the central region is warmer than coolant outside of the central region, and in response to the ambient temperature and the coolant temperature outside the central region being below respective threshold values, operating the pump to circulate coolant from the central region through the fuel cell stack such that ice formation is reduced in the fuel cell stack prior to purging the fuel cell stack with gases.

2. The method of claim 1 wherein the threshold value corresponds to five degrees Celsius or less.

3. The method of claim 1 wherein, after the vehicle shut down event and prior to circulating coolant, the coolant of the coolant system in the central region of the fuel cell stack is at a higher temperature than coolant in an edge region of the stack, the edge region having vias of an anode outlet for a cell in the fuel cell stack; and
wherein the coolant is circulated in the coolant system and through the fuel cell stack to increase a temperature of the edge region and the vias.

4. The method of claim 1 wherein the coolant is circulated through the fuel cell stack continuously for a predetermined time period after the coolant temperature outside of the fuel cell stack reaches a secondary threshold value and prior to purging.

5. The method of claim 1 wherein the coolant is circulated through the fuel cell stack by commanding a series of pulses of coolant flow in the coolant system after the coolant temperature outside of the fuel cell stack reaches a secondary threshold value and prior to purging.

6. The method of claim 1 further comprising: controlling a valve configured to control flow between a radiator and a radiator bypass passage in the coolant system, wherein the valve is controlled to direct the coolant flow through the bypass passage while circulating the coolant flow through the fuel cell stack.

7. The method of claim 1 further comprising: controlling a valve configured to control flow between a radiator and a radiator bypass passage in the coolant system, wherein the valve is controlled to blend the coolant flows from the radiator and the bypass passage to control coolant temperature and reduce an average temperature of the fuel cell stack while circulating the coolant flow through the fuel cell stack;
wherein purging is in response to the coolant temperature reaching a secondary threshold value.

8. A method of controlling a vehicle fuel cell system comprising:
shutting down a coolant system such that a pump is inoperative and a coolant flow rate through a fuel cell stack is zero with coolant present in both a central region of the fuel cell stack and outside the central region of the fuel cell stack; and
after the shutting down and responsive to a coolant temperature outside the central region and an ambient temperature outside the fuel cell stack each being less than a threshold temperature, operating the pump to circulate coolant from the central region through the fuel cell stack prior to purging the fuel cell stack with gas.

9. The method of claim 8 , wherein after the shutting down operating the pump, the coolant of the coolant system in the central region of the fuel cell stack is at a higher temperature than coolant in an edge region of the stack, the edge region having vias of an anode outlet for a cell in the fuel cell stack; and
wherein the coolant is circulated in the coolant system and through the fuel cell stack to increase a temperature of the edge region and the vias.

10. The method of claim 8 further comprising:
controlling a valve configured to control flow between a radiator and a radiator bypass passage in the coolant system, wherein the valve is controlled to direct the coolant flow through the bypass passage while circulating the coolant flow through the stack.

11. The method of claim 8 further comprising:
controlling a valve configured to control flow between a radiator and a radiator bypass passage in the coolant system, wherein the valve is controlled to blend coolant flows from the radiator and the bypass passage to control coolant temperature and reduce an average temperature of the fuel cell stack while circulating the coolant flow through the stack;
wherein purging is in response to the coolant temperature reaching a secondary threshold value.

Assignees

• Ford Motor Co

Inventors

• Riley Matthew
• Mathie Craig
• Milacic Milos

Classifications

• H01M8/04029 Primary

  Heat exchange using liquids · CPC title

• H01M8/04358

  of the coolant · CPC title

• H01M8/0432

  Temperature; Ambient temperature · CPC title

• H01M8/04228

  during shut-down · CPC title

• H01M8/04723

  of the coolant · CPC title