# US 2025/0096293 A1 · Fuel cell system

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- Number: US 2025/0096293 A1
- Document ID: US20250096293A1
- Status: Published application
- Kind: A1
- Application number: 18/882,022
- Filed: 2024-09-11
- Published: 2025-03-20
- Earliest claimed: 2023-09-19
- Assignees: Toyota Jidosha Kabushiki Kaisha
- Applicants: Toyota Jidosha Kabushiki Kaisha
- Inventors: Hiroshi FUJITANI
- Web page: https://patentgrep.com/patent/US20250096293A1

## CPC

- H01M 8/04947: {of auxiliary devices, e.g. batteries, capacitors}
- H01M 8/04029: Heat exchange using liquids
- H01M 8/04358: {of the coolant}
- H01M 8/04559: {of fuel cell stacks}
- H01M 8/04567: {of auxiliary devices, e.g. batteries, capacitors}
- H01M 8/04768: {of the coolant}
- H01M 8/0494: {of fuel cell stacks}
- H01M 16/006: {of fuel cells with rechargeable batteries}
- H01M 2220/20: Batteries in motive systems, e.g. vehicle, ship, plane
- H01M 2250/20: Fuel cells in motive systems, e.g. vehicle, ship, plane
- Y02E 60/50: Fuel cells
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A fuel cell system capable of maintaining the output of the fuel cell system. A fuel cell system, wherein the fuel cell system includes: a fuel cell stack, a cooling flow path configured to circulate cooling water for cooling the fuel cell stack in and out of the fuel cell stack, a radiator disposed on the cooling flow path, a bypass flow path branching from the cooling flow path upstream of the radiator of the cooling flow path, bypassing the radiator, and merging with the cooling flow path downstream of the radiator of the cooling flow path, a switching valve disposed at a branch point of the cooling flow path to the bypass flow path, a power supply, a voltmeter, and a secondary battery.

## Claims

### Claim 1

A fuel cell system,
wherein the fuel cell system comprises:
a fuel cell stack,
a cooling flow path configured to circulate cooling water for cooling the fuel cell stack in and out of the fuel cell stack,
a radiator disposed on the cooling flow path,
a bypass flow path branching from the cooling flow path upstream of the radiator of the cooling flow path, bypassing the radiator, and merging with the cooling flow path downstream of the radiator of the cooling flow path,
a switching valve disposed at a branch point of the cooling flow path to the bypass flow path and configured to switch between flowing the cooling water, which is discharged from the fuel cell stack, to the radiator and flowing the cooling water to the bypass flow path,
a power supply configured to supply power to the switching valve,
a voltmeter configured to measure a voltage of the power supply, and
a secondary battery, and
wherein, when the voltage of the power supply measured by the voltmeter is equal to or higher than a predetermined voltage, an upper limit of output from the secondary battery is set to a first output, and when the voltage of the power supply is lower than the predetermined voltage, the upper limit of the output from the secondary battery is set to a second output which is larger than the first output.

### Claim 2 (depends on 1)

The fuel cell system according to claim 1,
wherein a response time of the switching valve is estimated based on the voltage of the power supply measured by the voltmeter;
wherein a temperature of the cooling water flowing into the fuel cell stack is estimated based on the response time; and
wherein, when the estimated cooling water temperature is equal to or lower than a predetermined temperature, the upper limit of the output from the secondary battery is set to the second output.