Fuel cell system

Patent metadata

Field	Value
Publication number	US-10873094-B2
Application number	US-201214342167-A
Country	US
Kind code	B2
Filing date	Aug 2, 2012
Priority date	Sep 2, 2011
Publication date	Dec 22, 2020
Grant date	Dec 22, 2020

Abstract

A fuel cell system includes: a coolant circulation passage through which a coolant for cooling a fuel cell circulates; a pump that circulates the coolant; a radiation unit that cools the coolant by discharging heat from the coolant; a bypass passage connected to the coolant circulation passage so as to bypass the radiation unit; and an open/close valve that is provided in a convergence portion where low temperature coolant that has passed through the radiation unit and high temperature coolant that has passed through the bypass passage without passing through the radiation unit converge, and that opens when a temperature of the high temperature coolant reaches or exceeds a predetermined opening temperature, whereby the low temperature coolant and the high temperature coolant converge and are supplied thus to the fuel cell, wherein a basic discharge flow of the pump is calculated in accordance with a condition of the fuel cell, and when the temperature of the low temperature coolant is lower than a predetermined temperature, a discharge flow of the pump is increased above the basic discharge flow.

First claim

The invention claimed is:

1. A fuel cell system that generates power by supplying an anode gas and a cathode gas to a fuel cell, comprising:
a coolant circulation passage through which a coolant for cooling the fuel cell circulates;
a pump provided in the coolant circulation passage to circulate the coolant;
a radiation unit provided in the coolant circulation passage to cool the coolant by discharging heat from the coolant;
a bypass passage connected to the coolant circulation passage so as to bypass the radiation unit;
an open/close valve that is provided in a convergence portion where low temperature coolant that has passed through the radiation unit and high temperature coolant that has passed through the bypass passage without passing through the radiation unit converge, and that opens when a temperature of the high temperature coolant reaches or exceeds a predetermined opening temperature, such that the low temperature coolant and the high temperature coolant converge and are supplied to the fuel cell;
a first water temperature sensor that is provided in the coolant circulation passage, being positioned downstream of the fuel cell and upstream of the convergence portion; and
a controller programmed to:
calculate a basic discharge flow of the pump in accordance with a condition of the fuel cell comprising a temperature difference between a detected value by the first water temperature sensor and a target value of a stack outlet water temperature, the stack outlet water temperature being a temperature of a cooling water discharged from the fuel cell;
obtain an outside air temperature as a temperature of the low temperature coolant, the outside air temperature detected by an outside air temperature sensor;
set a discharge flow of the pump to the basic discharge flow when the outside air temperature is not lower than a predetermined temperature; and
increase the discharge flow of the pump above the basic discharge flow when the outside air temperature is lower than the predetermined temperature.

2. The fuel cell system as defined in claim 1 , wherein the controller is further programmed to steadily increase the discharge flow of the pump above the basic discharge flow as the temperature of the low temperature coolant decreases.

3. The fuel cell system as defined in claim 1 , wherein the controller is further programmed to vary the predetermined temperature on the basis of the basic discharge flow such that the predetermined temperature increases as the basic discharge flow decreases.

4. The fuel cell system as defined in claim 1 , wherein the controller is further programmed to start to increase the discharge flow of the pump when a temperature of the coolant that is supplied to the fuel cell after passing through the open/close valve reaches a predetermined increase start temperature, which is lower than the opening temperature of the open/close valve.

5. The fuel cell system as defined in claim 1 , wherein the controller is further programmed to stop increasing the discharge flow of the pump when the temperature of the coolant that is supplied to the fuel cell after passing through the open/close valve reaches a predetermined increase stop temperature, which is higher than the opening temperature of the open/close valve.

6. The fuel cell system as defined in claim 1 , wherein the controller is further programmed to reduce a pressure in a cathode gas passage inside the fuel cell when the discharge flow of the pump is increased above the basic discharge flow.

7. The fuel cell system as defined in claim 1 , wherein the controller is further programmed to increase a cathode gas supply flow when the discharge flow of the pump is increased above the basic discharge flow.

8. The fuel cell system as defined in claim 1 , further comprising:
a second water temperature sensor provided in the coolant circulation passage downstream of the bypass passage and a thermostat, the second water temperature sensor configured to detect a stack inlet water temperature;
wherein the open/close valve opens in response to the temperature detected by the first water temperature sensor reaching or exceeding the predetermined opening temperature.

9. The fuel cell system as defined in claim 1 , further comprising a second water temperature sensor that is provided in the coolant circulation passage at a location that is upstream of the fuel cell and downstream of the pump, wherein the second water temperature sensor detects a stack inlet water temperature.

10. A fuel cell system that generates power by supplying an anode gas and a cathode gas to a fuel cell, comprising:
a coolant circulation passage through which a coolant for cooling the fuel cell circulates;
a pump provided in the coolant circulation passage to circulate the coolant;
a radiation unit provided in the coolant circulation passage to cool the coolant by discharging heat from the coolant;
a bypass passage connected to the coolant circulation passage so as to bypass the radiation unit;
an open/close valve that is provided in a convergence portion where low temperature coolant that has passed through the radiation unit and high temperature coolant that has passed through the bypass passage without passing through the radiation unit converge, and that opens when a temperature of the high temperature coolant reaches or exceeds a predetermined opening temperature, such that the low temperature coolant and the high temperature coolant converge and are supplied to the fuel cell;
a first water temperature sensor that is provided in the coolant circulation passage, being positioned downstream of the fuel cell and upstream of the convergence portion; and
a controller programmed to:
calculate a basic discharge flow of the pump in accordance with a condition of the fuel cell comprising a temperature difference between a detected value by the first water temperature sensor and a target value of a stack outlet water temperature, the stack outlet water temperature being a temperature of a cooling water discharged from the fuel cell;
set a discharge flow of the pump to the basic discharge flow when a temperature of the low temperature coolant is not lower than a predetermined temperature; and
increase the discharge flow of the pump above the basic discharge flow when a temperature of the low temperature coolant is lower than the predetermined temperature,

wherein the predetermined temperature is a temperature at which hunting occurs in the open/close valve when the low temperature coolant converges with the high temperature coolant after the discharge flow of the pump is controlled to the basic discharge flow.

11. A control method for the fuel cell system as defined in claim 1 , the control method comprising:
calculating the basic discharge flow of the pump in accordance with the condition of the fuel cell; and
increasing the discharge flow of the pump above the basic discharge flow when the temperature of the low temperature coolant is lower than the predetermined temperature.

Assignees

• Chikugo Hayato
• Nishimura Hidetaka
• Nissan Motor

Inventors

• Chikugo Hayato
• Nishimura Hidetaka

Classifications

• Y02E60/50

  Fuel cells · CPC title

• H01M8/04768

  of the coolant · CPC title

• H01M8/04358

  of the coolant · CPC title

• H01M8/04074 Primary

  Heat exchange unit structures specially adapted for fuel cell · CPC title

• H01M8/04067 Primary

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