US-12626943-B2 - Fuel cell system

Abstract

The fuel cell system includes a fuel cell stack, a humidifier provided on an oxygen-containing gas supply flow path to humidify an oxygen-containing gas flowing through the oxygen-containing gas supply flow path, a discharge path stop valve provided on an oxygen-containing gas discharge flow path and configured to be opened during power generation by the fuel cell stack, and a pressure regulator provided downstream of the discharge path stop valve to regulate pressure so that it is higher on the upstream side than the downstream side.

Inventors

• Tomoyuki Inoue

Assignees

• HONDA MOTOR CO., LTD.

Dates

Publication Date

20260512

Application Date

20230322

Priority Date

20220329

Claims (5)

1. 1 . A fuel cell system comprising: a fuel cell stack configured to generate electric power by chemical reactions between a fuel gas and an oxygen-containing gas; an oxygen-containing gas supply flow path connected to the fuel cell stack; an oxygen-containing gas discharge flow path connected to the fuel cell stack; a humidifier disposed on the oxygen-containing gas supply flow path and configured to humidify the oxygen-containing gas flowing through the oxygen-containing gas supply flow path; a discharge path stop valve disposed on the oxygen-containing gas discharge flow path and configured to be opened while the fuel cell stack is generating electric power; a pressure regulator disposed downstream of the discharge path stop valve and configured to regulate a pressure on an upstream side to be higher than a pressure on a downstream side; an oxygen-containing gas supplier configured to supply the oxygen-containing gas to the fuel cell stack through the oxygen-containing gas supply flow path; a bypass channel branching off from the oxygen-containing gas supply flow path and merged with the oxygen-containing gas discharge flow path at a point between an upstream of the pressure regulator and a downstream of the discharge path stop valve; a bypass valve disposed on the bypass channel and configured to adjust a flow rate of the oxygen-containing gas flowing through the bypass channel; and a controller comprising one or more processors that are configured to execute computer-executable instructions stored in a memory, wherein the one or more processors execute the computer-executable instructions to cause the controller to: set a target supply amount of the oxygen-containing gas supplied to the fuel cell stack based on a target pressure at an oxygen-containing gas flow field inside the fuel cell stack and a target generated power amount of the fuel cell stack; control the oxygen-containing gas supplier to supply the oxygen-containing gas in the target supply amount; and adjust an opening degree of the bypass valve corresponding to the target supply amount.
2. 2 . The fuel cell system according to claim 1 , wherein the one or more processors cause the controller to: acquire an amount of supply of the oxygen-containing gas corresponding to the target pressure and an amount of the oxygen-containing gas required for the target generated power amount by using a map indicating relationships of an amount of the oxygen-containing gas with a pressure and a generated power amount; and set the target supply amount to a larger of the amount of supply corresponding to the target pressure or the amount of the oxygen-containing gas required for the target generated power amount.
3. 3 . The fuel cell system according to claim 2 , wherein the one or more processors cause the controller to: set the target supply amount at a predetermined cycle; and set a last set target supply amount as a current target supply amount in a case where an amount of supply currently acquired is larger than the amount of the oxygen-containing gas required for the target generated power amount and larger than the last set target supply amount.
4. 4 . The fuel cell system according to claim 1 , wherein the one or more processors cause the controller to: set an opening degree of the bypass valve correspondingly to a difference between the target supply amount and an amount of the oxygen-containing gas required for the target generated power amount in a case where the target supply amount is larger than the amount of the oxygen-containing gas required for the target generated power amount.
5. 5 . The fuel cell system according to claim 1 , wherein the one or more processors cause the controller to: set the target supply amount in a case in which an internal pressure at the oxygen-containing gas flow field is lower than the target pressure even when an opening degree of the discharge path stop valve is set equal to or lower than an opening degree corresponding to the target pressure, or a case in which the opening degree corresponding to the target pressure is lower than a lower limit opening degree of the discharge path stop valve.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2022-053076 filed on Mar. 29, 2022, the contents of which are incorporated herein by reference. BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a fuel cell system to be mounted on a moving object or the like. Description of the Related Art In recent years, fuel cells have attracted attention in various fields. For example, there is a fuel cell vehicle equipped with fuel cells. A fuel cell vehicle is powered by an electric motor running on electricity generated by electrochemical reactions in the fuel cells. For this reason, there is no discharge of CO2, NOx, SOx and the like as in gasoline-powered vehicles, but only water is discharged, and therefore fuel cell vehicles are environmentally friendly. The fuel cell may be mounted on other moving objects such as ships, aircrafts, robots and so on, in addition to automobiles. The fuel cell is formed of a membrane electrode assembly (MEA) in which an electrolyte membrane is provided between an anode and a cathode, and a pair of separators provided on both sides of the membrane electrode assembly. The fuel cells are also referred to as a fuel cell stack. JP 2012-221731 A discloses a fuel cell system having a fuel cell. An oxygen-containing gas supplier constituting the fuel cell system disclosed in JP 2012-221731 A includes an oxygen-containing gas supply flow path, an oxygen-containing gas discharge flow path, a compressor, a supply path stop valve, and a discharge path stop valve disposed in the oxygen-containing gas discharge flow path. The oxygen-containing gas supply flow path communicates with an oxygen-containing gas inlet of the fuel cell, and the oxygen-containing gas discharge flow path communicates with an oxygen-containing gas outlet of the fuel cell. The supply path stop valve is disposed in the oxygen-containing gas supply flow path, and the discharge path stop valve is disposed in the oxygen-containing gas discharge flow path. SUMMARY OF THE INVENTION In a situation where the fuel cell stack has a high temperature at low humidity, there is a tendency that the electrolyte membrane of the fuel cell stack dries so that degradation of the electrolyte membrane is accelerated. In the case where the fuel cell stack is mounted on a vehicle, such a situation in which the fuel cell stack has a high temperature at low humidity is likely to occur during uphill traveling or the like. When the pressure at the oxygen-containing gas flow field inside the fuel cell stack increases, the amount of water contained in the oxygen-containing gas flowing through the oxygen-containing gas flow field increases. Therefore, it is considered that the drying of the electrolyte membrane can be suppressed by increasing the pressure at the oxygen-containing gas flow field in side fuel cell stack. However, while the fuel cell stack is generating power, the stop valve disposed in the oxygen-containing gas discharge flow path cannot be closed. Therefore, it is required to increase the pressure in the oxygen-containing gas flow path in the fuel cell stack even when the fuel cell stack is generating power. An object of the present invention is to solve the above-described problems. According to an aspect of the present invention, there is provided a fuel cell system including: a fuel cell stack configured to generate electric power by chemical reactions between a fuel gas and an oxygen-containing gas; an oxygen-containing gas supply flow path connected to the fuel cell stack; an oxygen-containing gas discharge flow path connected to the fuel cell stack; a humidifier disposed on the oxygen-containing gas supply flow path and configured to humidify the oxygen-containing gas flowing through the oxygen-containing gas supply flow path; a discharge path stop valve disposed on the oxygen-containing gas discharge flow path and configured to be opened while the fuel cell stack is generating electric power; and a pressure regulator disposed downstream of the discharge path stop valve and configured to regulate a pressure on an upstream side to be higher than a pressure on a downstream side. According to the aspect of the present invention, even if the discharge path stop valve is opened while the fuel cell stack is generating electric power, it is possible to increase the pressure at the oxygen-containing gas flow field inside the fuel cell stack. As a result, because the amount of water contained in the oxygen-containing gas is increased as compared with the case where the pressure regulator is not provided, drying of the electrolyte membrane can be suppressed. The above and other objects, features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by wa