Fuel cell system and control method thereof

Patent metadata

Field	Value
Publication number	US-11271228-B2
Application number	US-201816226782-A
Country	US
Kind code	B2
Filing date	Dec 20, 2018
Priority date	Dec 21, 2017
Publication date	Mar 8, 2022
Grant date	Mar 8, 2022

Abstract

A fuel cell system includes a gas-liquid separator, a circulation flow path, a connecting flow path, and a distribution flow path. The gas-liquid separator separates fuel exhaust gas, which flows therein via a fuel exhaust gas flow path, into gas and liquid. The circulation flow path causes a gas discharge port of the gas-liquid separator and the fuel gas supply flow path to communicate with each other. The connecting flow path causes a liquid discharge port of the gas-liquid separator to communicate with the oxygen-containing gas supply flow path, via a drain valve. The distribution flow path causes the circulation flow path or a portion of the fuel gas supply flow path that is on a downstream side of a connecting section connecting to the circulation flow path to communicate with a downstream side of the drain valve of the connecting flow path via an opening and closing valve.

First claim

What is claimed is:

1. A fuel cell system for generating electric power by supplying fuel gas to an anode of a fuel cell via a fuel gas supply flow path and supplying an oxygen-containing gas to a cathode of the fuel cell via an oxygen-containing gas supply flow path, the fuel cell system comprising:
a fuel exhaust gas flow path configured to allow fuel exhaust gas discharged from the anode to flow therethrough;
a gas-liquid separator into which the fuel exhaust gas flows via the fuel exhaust gas flow path, the gas-liquid separator being configured to separate the fuel exhaust gas into a gas and a liquid;
a circulation flow path configured to cause a gas discharge port of the gas-liquid separator and the fuel gas supply flow path to be in communication with each other;
a connecting flow path configured to cause a liquid discharge port of the gas-liquid separator to be in communication with the oxygen-containing gas supply flow path, via a drain valve;
a control unit programmed to issue valve opening instructions to: the opening and closing valve, the drain valve, or both the opening and closing valve and the drain valve:
a distribution flow path configured to cause either the circulation flow path or a portion of the fuel gas supply flow path that is on a downstream side of a connecting section connecting to the circulation flow path to be in communication with a portion near the drain valve on a downstream side of the drain valve in the connecting flow path; and
an opening and closing valve configured to open and close the distribution flow path, wherein
the distribution flow path is opened to flow a mixed gas flowing through the fuel gas supply flow path on the downstream side of the connecting section or a discharge gas flowing through the circulation flow path, into the oxygen-containing gas supply flow path via the portion on the downstream side of the drain valve in the connecting flow path, and
wherein the opening and closing valve is in an open state, the drain valve is heated by heat of the mixed gas or heat of the discharge gas.

2. The fuel cell system according to claim 1 , wherein
the connecting section is provided with an ejector configured to mix together the fuel gas supplied to the fuel gas supply flow path and discharge gas discharged from the gas discharge port to the circulation flow path,
the ejector is supplied with the fuel gas via a solenoid valve, and
the distribution flow path causes a portion of the fuel gas supply flow path farther downstream than the ejector to be in communication with the downstream side of the drain valve in the connecting flow path.

3. The fuel cell system according to claim 1 , further comprising:
a temperature sensor configured to detect a temperature of the fuel cell system;
wherein the control unit is programmed to issue valve opening instructions to both the opening and closing valve and the drain valve when a detection result of the temperature sensor is less than or equal to a drain valve heating prioritization temperature, which is set in advance, at a time when a warm-up of the fuel cell begins, and wherein
the drain valve opens and closes due to energization.

4. The fuel cell system according to claim 3 , wherein
the control unit is programmed to issue the valve opening instructions only to the opening and closing valve when the detection result of the temperature sensor is greater than the drain valve heating prioritization temperature at the time when the warm-up begins; and
the control unit is programmed to issue the valve opening instructions to the drain valve after it is detected that the detection result of the temperature sensor is greater than or equal to a drain valve unfreezing temperature that is set in advance.

5. The fuel cell system according to claim 3 , further comprising:
a pressure sensor configured to detect pressure of gas circulating through a portion of the fuel gas supply flow path farther downstream than the connecting section, the fuel exhaust gas flow path, and the circulation flow path, wherein
the control unit is programmed to judge whether the drain valve is open, based on a detection result of the pressure sensor.

6. The fuel cell system according to claim 5 , wherein
if it is judged that the drain valve is open after the valve opening instructions have been issued to each of the drain valve and the opening and closing valve, the control unit is programed to issue valve closing instructions to the opening and closing valve.

7. A control method of a fuel cell system for generating electric power by supplying fuel gas to an anode of a fuel cell via a fuel gas supply flow path and supplying an oxygen-containing gas to a cathode of the fuel cell via an oxygen-containing gas supply flow path, the control method comprising:
a freezing judgment step of judging, by a control unit, whether a drain valve configured to discharge a discharge fluid from a liquid discharge port of a gas-liquid separator is frozen, the gas-liquid separator being configured to separate fuel exhaust gas discharged from the anode into a gas and a liquid, the discharge fluid including the liquid, wherein the control unit is programmed to issue valve opening instructions to: an opening and closing valve, the drain valve, or both an opening and closing valve and the drain valve, wherein
in the freezing judgment step, if it is judged that the drain valve is not frozen, the drain valve is kept in an open state and an unconsumed portion of the fuel gas contained in the discharge fluid is supplied along with the oxygen-containing gas to the cathode, and
in the freezing judgment step, if it is judged that the drain valve is frozen, the opening and closing valve of a distribution flow path is kept in an open state, the distribution flow path being configured to distribute a discharge gas that is discharged from a gas discharge port of the gas-liquid separator or a mixed gas containing the discharge gas and the fuel gas supplied to the fuel gas supply flow path, to a downstream side of the drain valve in a connecting flow path configured to cause the liquid discharge port and the oxygen-containing gas supply flow path to be in communication with each other via the drain valve, the mixed gas or the discharged gas is supplied to a portion near the drain valve in the connecting flow path to heat the drain valve by heat of the mixed gas or heat of the discharge gas.

8. The control method of the fuel cell system according to claim 7 , further comprising:
a selection step of, before the freezing judgment step, selecting which of heating the drain valve and heating the fuel cell is to be prioritized, based on a detection result of a temperature of the fuel cell system.

9. The control method of the fuel cell system according to claim 8 , wherein
the opening and closing valve opens and closes by energization,
in the selection step, if heating of the drain valve is selected to be prioritized, the valve opening instructions are issued to both the opening and closing valve and the drain valve, and
if heating of the fuel cell is selected to be prioritized, the valve opening instructions are issued only to the opening and closing valve, and the valve opening instructions are issued to the drain valve when the temperature of the fuel cell system reaches a temperature at which the drain valve unfreezes.

10. The control method of the fuel cell system according to claim 9 , wherein
the freezing judgment step is performed in a state where the valve opening instructions have been issued to each of the drain valve and the opening and closing valve, and if it is judged that the drain valve is not frozen, valve closing instructions are issued to the opening and closi

Assignees

• Honda Motor Co Ltd

Inventors

• Okamura Yuji
• Takaku Koichi
• Kato Koichi

Classifications

• Y02E60/50

  Fuel cells · CPC title

• H01M8/0432

  Temperature; Ambient temperature · CPC title

• H01M8/04302

  applied during start-up · CPC title

• H01M8/04253 Primary

  Means for solving freezing problems · CPC title

• H01M8/0258

  characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant · CPC title