Fuel cell system

Patent metadata

Field	Value
Publication number	US-11742499-B2
Application number	US-202217653405-A
Country	US
Kind code	B2
Filing date	Mar 3, 2022
Priority date	Mar 4, 2021
Publication date	Aug 29, 2023
Grant date	Aug 29, 2023

Abstract

To provide a fuel cell system configured to reduce false cross leak judgment. A fuel cell system wherein the controller preliminarily stores a first data group indicating a relationship between the flow rate of the oxidant gas, the opening degree of the bypass valve, and the hydrogen concentration of the oxidant off-gas; and wherein before the controller determines whether or not a cross leak has occurred, the controller varies the hydrogen concentration threshold used for determining whether or not a cross leak has occurred, by comparing the flow rate of the oxidant gas measured by the oxidant gas flow rate sensor and the opening degree of the bypass valve with the first data group.

First claim

The invention claimed is:

1. A fuel cell system,
wherein the fuel cell system comprises:
a fuel cell,
an oxidant gas supplier for supplying oxidant gas to the fuel cell,
an oxidant gas supply flow path connecting the oxidant gas supplier and an oxidant gas inlet of the fuel cell,
an oxidant gas flow rate sensor disposed in the oxidant gas supply flow path,
an oxidant off-gas discharge flow path for allowing oxidant off-gas to be discharged from an oxidant gas outlet of the fuel cell to the outside,
an oxidant gas bypass flow path branching from the oxidant gas supply flow path,
bypassing the fuel cell, and connecting a branch of the oxidant gas supply flow path and a first junction of the oxidant off-gas discharge flow path,
a bypass valve disposed in the oxidant gas bypass flow path,
a hydrogen concentration sensor disposed downstream from the first junction of the oxidant off-gas discharge flow path, and
a controller,
wherein the controller controls driving of the oxidant gas supplier and controls an opening degree of the bypass valve;
wherein the controller determines whether or not a cross leak has occurred, from the hydrogen concentration of the oxidant off-gas measured by the hydrogen concentration sensor;
wherein, when the hydrogen concentration of the oxidant off-gas measured by the hydrogen concentration sensor is equal to or more than a predetermined threshold, the controller determines that a cross leak has occurred;
wherein the controller preliminarily stores a first data group indicating a relationship between the flow rate of the oxidant gas, the opening degree of the bypass valve, and the hydrogen concentration of the oxidant off-gas;
wherein before the controller determines whether or not a cross leak has occurred, the controller varies the hydrogen concentration threshold used for determining whether or not a cross leak has occurred, by comparing the flow rate of the oxidant gas measured by the oxidant gas flow rate sensor and the opening degree of the bypass valve with the first data group; and
wherein the fuel cell system further comprises:
a cathode gas-liquid separator disposed upstream from the first junction of the oxidant off-gas discharge flow path, and
a water discharge flow path for allowing liquid water to be discharged from the cathode gas-liquid separator.

2. The fuel cell system according to claim 1 ,
wherein the fuel cell system further comprises a temperature sensor for detecting a temperature of the fuel cell;
wherein the oxidant gas supplier is an air compressor;
wherein the controller preliminarily stores a second data group indicating a relationship between a rotational frequency of the air compressor, the temperature of the fuel cell, and the hydrogen concentration of the oxidant off-gas; and
wherein before the controller determines whether or not a cross leak has occurred, the controller varies the hydrogen concentration threshold used for determining whether or not a cross leak has occurred, by comparing the rotational frequency of the air compressor and the temperature of the fuel cell measured by the temperature sensor with the second data group.

3. The fuel cell system according to claim 1 ,
wherein the fuel cell system further comprises:
a fuel gas supplier for supplying fuel gas to the fuel cell,
a fuel gas supply flow path connecting a fuel gas inlet of the fuel cell and the fuel gas supplier,
an ejector disposed in the fuel gas supply flow path,
a fuel off-gas discharge flow path for discharging, to the outside of the fuel cell system, the fuel off-gas discharged from a fuel gas outlet of the fuel cell,
an anode gas-liquid separator disposed in the fuel off-gas discharge flow path,
a vent and discharge valve disposed downstream from the anode gas-liquid separator of the fuel off-gas discharge flow path, and
a circulation flow path connecting the anode gas-liquid separator and the ejector;
wherein the oxidant off-gas discharge flow path includes, downstream from the first junction, a second junction where the fuel off-gas discharge flow path joins the oxidant off-gas discharge flow path; and
wherein the hydrogen concentration sensor is disposed in a region between the first and second junctions of the oxidant off-gas discharge flow path.

4. The fuel cell system according to claim 1 ,
wherein, before the controller determines whether or not a cross leak has occurred, the controller determines whether or not the bypass valve is opened;
wherein, when the controller determines that the bypass valve is opened, the controller sets the hydrogen concentration threshold used for determining whether or not a cross leak has occurred, to a second concentration threshold C 2 which is larger than a first concentration threshold C 1 ; and
wherein, when the controller determines that the bypass valve is closed, the controller sets the hydrogen concentration threshold used for determining whether or not a cross leak has occurred, to the first concentration threshold C 1 .

5. The fuel cell system according to claim 4 ,
wherein the fuel cell system further comprises a temperature sensor for detecting a temperature of the fuel cell;
wherein, before the controller determines whether or not a cross leak has occurred, the controller determines whether or not the temperature of the fuel cell detected by the temperature sensor is equal to or less than an optimum predetermined temperature threshold for operation of the fuel cell;
wherein, when the controller determines that the temperature of the fuel cell detected by the temperature sensor exceeds the optimum predetermined temperature threshold for the operation of the fuel cell, the controller sets the hydrogen concentration threshold used for determining whether or not a cross leak has occurred, to the first concentration threshold C 1 ;
wherein, when the controller determines that the temperature of the fuel cell detected by the temperature sensor is equal to or less than the optimum predetermined temperature threshold for the operation of the fuel cell, the controller determines whether or not the bypass valve is opened;
wherein, when the controller determines that the bypass valve is opened, the controller sets the hydrogen concentration threshold used for determining whether or not a cross leak has occurred, to the second concentration threshold C 2 ; and
wherein, when the controller determines that the bypass valve is closed, the controller sets the hydrogen concentration threshold used for determining whether or not a cross leak has occurred, to the first concentration threshold C 1 .

6. The fuel cell system according to claim 4 ,
wherein the fuel cell system further comprises a current sensor for detecting a current value of the fuel cell;
wherein, before the controller determines whether or not a cross leak has occurred, the controller determines whether or not the current value of the fuel cell detected by the current sensor is equal to or less than a predetermined current threshold;
wherein, when the controller determines that the current value of the fuel cell detected by the current sensor exceeds the predetermined current threshold, the controller sets the hydrogen concentration threshold used for determining whether or not a cross leak has occurred, to the first concentration threshold C 1 ;
wherein, when the controller determines that the current value of the fuel cell detected by the current sensor is equal to or less than the predetermined current threshold, the controller determines whether or not the bypass valve is opened;
wherein, when the controller determines that the bypass valve is opened, the controller sets the hydrogen concentration threshold used for determining whether or not a cross leak has occurred, to the second concentration th

Assignees

• Toyota Motor Co Ltd

Inventors

• Matsusue Masaaki

Classifications

• H01M8/04164 Primary

  by condensers, gas-liquid separators or filters · CPC title

• H01M8/0432

  Temperature; Ambient temperature · CPC title

• H01M8/04201

  Reactant storage and supply, e.g. means for feeding, pipes · CPC title

• H01M8/04395 Primary

  of cathode reactants at the inlet or inside the fuel cell · CPC title

• H01M8/04589

  of fuel cell stacks · CPC title