Fuel cell system and hydrogen leak decision method in fuel cell system

Patent metadata

Field	Value
Publication number	US-2018233755-A1
Application number	US-201715852549-A
Country	US
Kind code	A1
Filing date	Dec 22, 2017
Priority date	Feb 10, 2017
Publication date	Aug 16, 2018
Grant date	—

Abstract

A fuel cell system includes: a fuel cell; a hydrogen tank; a hydrogen supply flow path configured to connect the hydrogen tank and the fuel cell to each other; a valve element configured to, when closed, shut off supply of hydrogen from the hydrogen tank to the hydrogen supply flow path; a pressure sensor; a pressure reducer configured to reduce internal pressure of the hydrogen supply flow path; and a controller configured to decide presence or absence of a hydrogen leak in the fuel cell system upon a power-generation halt of the fuel cell. The controller: while closing the valve element, reduces the internal pressure of the hydrogen supply flow path to a first pressure value by the pressure reducer; after the pressure reduction to the first pressure value, decides presence or absence of a suspicion of a hydrogen leak by using a variation of a pressure value acquired from the pressure sensor; when deciding a suspicion of a hydrogen leak is presence, reduces the internal pressure of the hydrogen supply flow path to a second pressure value lower than the first pressure value by the pressure reducer; and after the pressure reduction to the second pressure value, decides the presence or absence of a hydrogen leak by using a variation of a pressure value acquired from the pressure sensor.

First claim

What is claimed is:

1 . A fuel cell system comprising:
a fuel cell; a hydrogen tank configured to store hydrogen therein; a hydrogen supply flow path configured to connect the hydrogen tank and the fuel cell to each other; a valve element configured to, when closed, shut off supply of hydrogen from the hydrogen tank to the hydrogen supply flow path; a pressure sensor for detecting an internal pressure value of the hydrogen supply flow path; a pressure reducer configured to reduce internal pressure of the hydrogen supply flow path; and a controller configured to decide presence or absence of a hydrogen leak in the fuel cell system upon a power-generation halt of the fuel cell, wherein the controller: while closing the valve element, reduces the internal pressure of the hydrogen supply flow path to a first pressure value by the pressure reducer; after the pressure reduction to the first pressure value, decides presence or absence of a suspicion of a hydrogen leak by using a variation of a pressure value acquired from the pressure sensor; when deciding that a suspicion of a hydrogen leak is presence, reduces the internal pressure of the hydrogen supply flow path to a second pressure value lower than the first pressure value by the pressure reducer; and after the pressure reduction to the second pressure value, decides the presence or absence of a hydrogen leak by using a variation of a pressure value acquired from the pressure sensor.

2 . The fuel cell system in accordance with claim 1 , wherein
the controller:
by using a variation of a pressure value acquired from the pressure sensor, decides whether the suspicion of a hydrogen leak is a suspicion of an internal leak which is a hydrogen leak from the valve element to the hydrogen supply flow path; and
when deciding that the suspicion of a hydrogen leak is the suspicion of an internal leak, reduces the internal pressure value of the hydrogen supply flow path to the second pressure value.

3 . The fuel cell system in accordance with claim 1 , wherein
the controller:
decides the presence or absence of a suspicion of a hydrogen leak by using a variation of a pressure value acquired from the pressure sensor resulting over a time period from the internal pressure reduction of the hydrogen supply flow path to the first pressure value until a lapse of a first decision time; and
decides the presence or absence of a hydrogen leak by using a variation of a pressure value acquired from the pressure sensor resulting over a time period from the internal pressure reduction of the hydrogen supply flow path to the second pressure value until a lapse of a second decision time longer than the first decision time.

4 . The fuel cell system in accordance with claim 3 , wherein
the controller decides that no suspicion of a hydrogen leak is presence when a sum value of a first hydrogen leak flow rate and a sensor error-equivalent flow rate has come to a predetermined value or lower before a lapse of the first decision time, the first hydrogen leak flow rate being calculated by using an absolute value of a variation of a pressure value acquired from the pressure sensor resulting over a time period having elapsed since the internal pressure reduction of the hydrogen supply flow path to the first pressure value as well as using a volume of the hydrogen supply flow path whose pressure value is detected by the pressure sensor, and the sensor error-equivalent flow rate being calculated by using an absolute value of a pressure value equivalent to an error of the pressure sensor as well as using the volume; the controller decides that a suspicion of a hydrogen leak is presence when the sum value of the first hydrogen leak flow rate and the sensor error-equivalent flow rate has not come to the predetermined value or lower before a lapse of the first decision time; the controller decides that no hydrogen leak is presence when a sum value of a second hydrogen leak flow rate and the sensor error-equivalent flow rate has come to the predetermined value or lower before a lapse of the second decision time, the second hydrogen leak flow rate being calculated by using an absolute value of a variation of a pressure value acquired from the pressure sensor resulting over a time period having elapsed since the internal pressure reduction of the hydrogen supply flow path to the second pressure value as well as using the volume; and the controller decides that a hydrogen leak is presence when the sum value of the second hydrogen leak flow rate and the sensor error-equivalent flow rate has not come to the predetermined value or lower before a lapse of the second decision time.

5 . The fuel cell system in accordance with claim 1 , further comprising:
a shutoff member provided on one side of the hydrogen supply flow path closer to the fuel cell than the pressure sensor and which is configured to serve for shutting off hydrogen supplied to the fuel cell, wherein the controller decides the presence or absence of a hydrogen leak in part of the hydrogen supply flow path ranging from the hydrogen tank to the shutoff member.

6 . The fuel cell system in accordance with claim 2 , wherein
when the controller decides that a suspicion of a hydrogen leak is presence, the controller decides whether the suspicion of a hydrogen leak is a suspicion of an internal leak or a suspicion of an external leak from the hydrogen supply flow path to exterior of the hydrogen supply flow path, by using positivity or negativity of a variation of a pressure value acquired from the pressure sensor; when the controller decides that the suspicion of a hydrogen leak is the suspicion of an external leak, the controller executes a pressurization process for pressurizing the internal pressure of the hydrogen supply flow path to a third pressure value by opening the valve element; and after the pressurization process, the controller decides whether the presence or absence of a hydrogen leak, by using a variation of a pressure value acquired from the pressure sensor.

7 . The fuel cell system in accordance with claim 6 , wherein
the controller:
when deciding that the suspicion of a hydrogen leak is a suspicion of an external leak, decides whether a pressure value acquired from the pressure sensor is lower than the third pressure value; and
executes the pressurization process when the pressure value is lower than the third pressure value.

8 . The fuel cell system in accordance with claim 6 , wherein
the controller:
decides the presence or absence of a suspicion of a hydrogen leak, by using a variation of a pressure value acquired from the pressure sensor resulting over a time period from the internal pressure reduction of the hydrogen supply flow path to the first pressure value until a lapse of the first decision time; and
decides the presence or absence of a hydrogen leak, by using a variation of a pressure value acquired from the pressure sensor resulting over a time period from the internal pressurization of the hydrogen supply flow path to the third pressure value until a lapse of a third decision time longer than the first decision time.

9 . The fuel cell system in accordance with claim 8 , wherein
the controller decides that no suspicion of a hydrogen leak is presence when a sum value of a first hydrogen leak flow rate and a sensor error-equivalent flow rate has come to a predetermined value or lower before a lapse of the first decision time, the first hydrogen leak flow rate being calculated by using an absolute value of a variation of a pressure value acquired from the pressure sensor resulting over a time period having elapsed since the internal pressure reduction of the hydrogen supply flow path to the fir

Assignees

• Toyota Motor Co Ltd

Inventors

• Saito Hiromu

Classifications

• H01M8/04753 Primary

  of fuel cell reactants · CPC title

• H01M8/04679 Primary

  of fuel cell stacks · CPC title

• H01M8/0438

  Pressure; Ambient pressure; Flow · CPC title

• H01M8/04992

  characterised by the implementation of mathematical or computational algorithms, e.g. feedback control loops, fuzzy logic, neural networks or artificial intelligence · CPC title

• H01M8/04388

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