Fuel-circulating fuel cell system

• US 20030096145A1
• Filed: 11/20/2002
• Published: 05/22/2003
• Est. Priority Date: 11/20/2001
• Status: Active Grant

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Shimanuki, Hiroshi, Sugawara, Tatsuya
• Granted Patent: US 7,547,481 B2
• Time in Patent Office: Days
• US Class Current: 429/432
• CPC Class Codes: H01M 8/04097 with recycling of the reactants H01M8/04119, H01M8/04104 take precedence
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A fuel cell stack 1 in a fuel-circulating fuel cell system is supplied with fuel and an oxidizing agent to generate electricity. The fuel discharged from the fuel cell stack 1 is supplied to the fuel cell stack 1 again through a fuel-circulating passage 6. In the fuel-circulating passage 6 is provided a fuel pump 3 powered from an outside source to circulate the fuel through the fuel-circulating passage 6 at a predetermined circulation rate. An ECU 4 transmits an output instruction value to the fuel cell stack 1 and regulates a circulation rate of the fuel in the fuel-circulating passage 6 according to the output instruction value.

Claims

1. A fuel-circulating fuel cell system comprising:

a fuel cell that is supplied with fuel and an oxidizing agent, and generates electricity;

a fuel-circulating passage that supplies fuel discharged from the fuel cell to the fuel cell again;

a fuel-forwarding device disposed in the fuel-circulating passage and provided with a fuel pump that is powered from an outside source to circulate the fuel in the fuel-circulating passage at a predetermined circulation rate; and

a fuel cell controller that transmits an output instruction value to the fuel cell and controls the fuel-forwarding device according to the output instruction value, to regulate a circulation rate of the fuel in the fuel-circulating passage.

2. A fuel-circulating fuel cell system according to claim 1, wherein the fuel-forwarding device is further provided with an ejector to supply new fuel to the fuel-circulating passage and circulate the fuel in the fuel-circulating passage at a predetermined circulation rate in combination with the fuel pump.

3. A fuel-circulating fuel cell system according to claim 1, wherein the fuel cell controller monitors a condition level of the fuel cell.

4. A fuel-circulating fuel cell system according to claim 1, wherein the fuel cell controller determines a target rotation speed of the fuel pump based upon the output instruction value transmitted to the fuel cell.

5. A fuel-circulating fuel cell system according to claim 4, wherein the fuel cell controller includes a control map that indicates a relationship between the output instruction value and the target rotation speed of the fuel cell, wherein the fuel cell controller looks up the control map to determine the target rotation speed of the fuel pump based upon the output instruction value transmitted to the fuel cell.

6. A fuel-circulating fuel cell system according to claim 3, wherein the fuel cell controller determines a target rotation speed of the fuel pump based upon the output instruction value transmitted to the fuel cell, and calculates a rotation correction coefficient based upon the condition level;

and

wherein the fuel cell controller controls the fuel pump so that the fuel pump rotates at the target rotation speed corrected with the rotation correction coefficient.

7. A fuel-circulating fuel cell system according to claim 3, wherein the fuel cell controller determines a target rotation speed of the fuel pump based upon the output instruction value transmitted to the fuel cell, and calculates a rotation correction coefficient based upon the condition level and the output instruction value;

and

wherein the fuel cell controller controls the fuel pump so that the fuel pump rotates at the target rotation speed corrected with the rotation correction coefficient.

8. A fuel-circulating fuel cell system according to claim 6, wherein the condition level includes a cell voltage of the fuel cell, and/or a dew point of the fuel at an inlet to the fuel cell.

9. A fuel-circulating fuel cell system according to claim 1, wherein the fuel cell controller determines a target rotation speed of the fuel pump based upon the output instruction value, and obtains an output increase/decrease rate as a rate of change of the output instruction value with respect to time;

and

wherein the fuel cell controller calculates a rotation correction coefficient based upon the output increase/decrease rate, and controls the fuel pump so that the fuel pump rotates at a rotation speed obtained by correcting the target rotation speed with the rotation correction coefficient.

10. A fuel-circulating fuel cell system according to claim 1, wherein the fuel cell controller determines a target rotation speed of the fuel pump based upon the output instruction value, and obtains an output increase/decrease rate as a rate of change of the output instruction value with respect to time;

and

wherein the fuel cell controller calculates a rotation correction coefficient based upon the output increase/decrease rate and the output instruction value, and controls the fuel pump so that the fuel pump rotates at a rotation speed obtained by correcting the target rotation speed with the rotation correction coefficient.

11. A fuel-circulating fuel cell system according to claim 9, wherein the fuel cell controller calculates an operation time of the fuel pump based upon the output instruction value and the output increase/decrease rate, and controls the fuel pump so that the fuel pump rotates during the operation time.

12. A fuel-circulating fuel cell system according to claim 3, wherein the fuel-circulating passage includes a bypass that detours round the fuel pump, and a bypass valve that is operated by the fuel cell controller to open and close based upon the condition level;

and

wherein the bypass valve is opened when the condition level falls within a predetermined range, while the bypass valve is closed when the condition level is out of the predetermined range, so that the fuel pump is rotated at a rotation speed according to the condition level.

13. A fuel-circulating fuel cell system according to claim 3, wherein the fuel cell controller stops the fuel pump when the condition level falls within the predetermined range.

14. A fuel-circulating fuel cell system according to claim 3, wherein the fuel cell controller lets the fuel pump idle when the condition level falls within the predetermined range.