Fuel cell system and control method thereof

Patent metadata

Field	Value
Publication number	US-9954234-B2
Application number	US-201615094328-A
Country	US
Kind code	B2
Filing date	Apr 8, 2016
Priority date	Apr 10, 2015
Publication date	Apr 24, 2018
Grant date	Apr 24, 2018

Abstract

A fuel cell system comprises a fuel cell stack, radiator, stack side cooling water passage, radiator side cooling water passage, bypass cooling water passage, deionizer, stack side cooling water pump, and radiator side cooling water pump. The pump are formed from rotary pumps able to change directions and amounts of cooling water discharged by changes of drive speeds. Drive speeds of the pumps are controlled to thereby control an amount of cooling water flowing through the radiator side cooling water passage, an amount of the cooling water flowing through the stack side cooling water passage, and a direction and amount of the cooling water flowing through the bypass cooling water passage.

First claim

What is claimed is:

1. A fuel cell system comprising:
a fuel cell stack configured to generate electric power by an electrochemical reaction between fuel gas and an oxidizing gas;
a radiator configured to lower a temperature of a cooling water for the fuel cell stack;
a cooling water feed passage connecting an outlet of an in-radiator cooling water passage in the radiator and an inlet of an in-stack cooling water passage in the fuel cell stack with each other, and a cooling water discharge passage connecting an outlet of the in-stack cooling water passage and an inlet of the in-radiator cooling water passage with each other, the cooling water feed passage comprising a feed side branching point, a radiator outflow passage from the outlet of the in-radiator cooling water passage to the feed side branching point, and a stack inflow passage from the feed side branching point to the inlet of the in-stack cooling water passage, the cooling water discharge passage comprising a discharge side branching point, a stack outflow passage from the outlet of the in-stack cooling water passage to the discharge side branching point, and a radiator inflow passage from the discharge side branching point to the inlet of the in-radiator cooling water passage, the stack inflow passage, the in-stack cooling water passage, and the stack outflow passage configuring a stack side cooling water passage, and the radiator inflow passage, the in-radiator cooling water passage, and the radiator outflow passage configuring a radiator side cooling water passage;
a bypass cooling water passage connecting the feed side branching point and the discharge side branching point with each other, through which the cooling water can flow between the feed side branching point and the discharge side branching point in both directions;
a stack side cooling water pump able to change an amount of the cooling water discharged, but not able to change a direction of the cooling water discharged, the stack side cooling water pump being arranged in one of the stack inflow passage so that an outlet thereof faces the fuel cell stack and the stack outflow passage so that an inlet thereof faces the fuel cell stack;
a radiator side cooling water pump formed from a rotary pump changes a direction and amount of the cooling water discharged by a change of a drive speed thereof, the radiator side cooling water pump having a property that a discharge amount in a forward direction becomes greater as the drive speed becomes greater when the drive speed is a positive value and the discharge amount in a reverse direction becomes greater as the drive speed becomes smaller when the drive speed is a negative value, and the radiator side cooling water pump being arranged in one of the radiator inflow passage so that an outlet thereof, when the discharge direction is the forward direction, faces the radiator and the radiator outflow passage so that an inlet thereof, when the discharge direction is the forward direction, faces the radiator; and
a controller configured to control the stack side cooling water pump and the radiator side cooling water pump, respectively, to thereby control an amount of the cooling water flowing through the stack side cooling water passage, control an amount of the cooling water flowing through the radiator side cooling water passage, and change a direction and amount of the cooling water flowing through the bypass cooling water passage, respectively.

2. The fuel cell system according to claim 1 ,
wherein, if the stack side cooling water pump is driven and a drive speed of the radiator side cooling water pump is set to a radiator bypass speed which is a negative value, the cooling water having flowed through the stack side cooling water passage flows into the bypass cooling water passage while an insignificant amount of cooling water flows into the radiator side cooling water passage at the discharge side branching point, and
wherein the controller is configured to drive the stack side cooling water pump and set a drive speed of the radiator side cooling water pump to the radiator bypass speed to thereby perform a radiator full bypass mode operation where the cooling water circulates through the stack side cooling water passage and the bypass cooling water passage while an insignificant amount flows through the radiator side cooling water passage.

3. The fuel cell system according to claim 1 ,
wherein, if the stack side cooling water pump is driven and a drive speed of the radiator side cooling water pump is set to a radiator bypass speed which is a negative value, the cooling water having flowed through the stack side cooling water passage flows into the bypass cooling water passage while an insignificant amount flows into the radiator side cooling water passage at the discharge side branching point, and
wherein the controller is configured to drive the stack side cooling water pump and set a drive speed of the radiator side cooling water pump to one of a negative value greater than the radiator bypass speed, zero, and a positive value to thereby perform a radiator partial bypass mode operation where the cooling water circulates through the stack side cooling water passage and the bypass cooling water passage while it flows through the radiator side cooling water passage.

4. The fuel cell system according to claim 2 , wherein the controller is configured to one of:
drive the stack side cooling water pump and set a drive speed of the radiator side cooling water pump to a positive value to thereby perform a bypass-less mode operation where the cooling water circulates through the stack side cooling water passage and the radiator side cooling water passage while an insignificant amount flows through the bypass cooling water passage; and
at least one of drive and stop the stack side cooling water pump and set a drive speed of the radiator side cooling water pump to a positive value to thereby perform a stack partial bypass mode operation where the cooling water circulates through the radiator side cooling water passage and the bypass cooling water passage while it flows through the stack side cooling water passage.

5. A method of control of a fuel cell system, the fuel cell system comprising:
a fuel cell stack configured to generate electric power by an electrochemical reaction between fuel gas and an oxidizing gas;
a radiator configured to lower a temperature of a cooling water for the fuel cell stack;
a cooling water feed passage connecting an outlet of an in-radiator cooling water passage in the radiator and an inlet of an in-stack cooling water passage in the fuel cell stack with each other, and a cooling water discharge passage connecting an outlet of the in-stack cooling water passage and an inlet of the in-radiator cooling water passage with each other, the cooling water feed passage comprising a feed side branching point, a radiator outflow passage from the outlet of the in-radiator cooling water passage to the feed side branching point, and a stack inflow passage from the feed side branching point to the inlet of the in-stack cooling water passage, the cooling water discharge passage comprising a discharge side branching point, a stack outflow passage from the outlet of the in-stack cooling water passage to the discharge side branching point, and a radiator inflow passage from the discharge side branching point to the inlet of the in-radiator cooling water passage, the stack inflow passage, the in-stack cooling water passage, and the stack outflow passage configuring a stack side cooling water passage, and the radiator inflow passage, the in-radiator cooling water passage, and the radiator outflow passage configuring a radiator side cooling water passage;
a bypass cooling water passage connecting the feed side branching point and the discharge side branch

Assignees

• Toyota Motor Co Ltd

Inventors

• Sato Hiromichi
• Hasegawa Shigeki
• Iio Atsuo

Classifications

• H01M8/04723

  of the coolant · CPC title

• H01M8/04067 Primary

  Heat exchange or temperature measuring elements, thermal insulation, e.g. heat pipes, heat pumps, fins · CPC title

• H01M8/04768

  of the coolant · CPC title

• H01M8/04029 Primary

  Heat exchange using liquids · CPC title

• H01M8/1004

  characterised by membrane-electrode assemblies [MEA] (H01M8/12 takes precedence) · CPC title