JP2010274675A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle-mounted type of fuel cell system capable of efficiently cooling a fuel cell. <P>SOLUTION: On a vehicle, an EV radiator 16, an FC radiator 15, and a main radiator fan 13 are disposed at a front part thereof, allowing a grille 21 to take in travel wind. The vehicle has a motor compartment containing a motor and a drive system for driving the vehicle, and the travel wind is introduced to a fuel cell casing 10 mounted in an underfloor part of the vehicle. A subsidiary radiator 17 is disposed below the fuel cell casing 10, and a subsidiary radiator fan 14 is disposed behind the fuel cell casing 10 to discharge air around the subsidiary radiator 17, which is merged from an airflow from the main radiator fan 13 and the travel wind introduced from a cowl top louver 23. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fuel cell system in which a fuel cell stack is mounted under a vehicle floor, and more particularly, to a fuel cell system in which components for cooling the fuel cell stack are provided in a space under the floor.

  In general, in a fuel cell vehicle that uses a fuel cell as a power source, for convenience of vehicle layout, a fuel cell stack is mounted at the bottom of the floor panel, and cooling water is used to prevent overheating due to heat generation of the fuel cell stack due to power generation. The used heat exchanger and the radiator of the vehicle front part which discharge | releases the heat of a cooling water are provided.

  A solid molecular charge type fuel cell used in a fuel cell vehicle has a relatively low operating upper limit temperature, and has a smaller temperature difference from the atmosphere than an operating upper limit temperature for an internal combustion engine such as a so-called engine. In order to obtain sufficient cooling capacity, a large radiator that can take in a large amount of cooling air is required.

  Furthermore, the fuel cell vehicle has a heat exchanger not only for cooling the fuel cell stack but also for cooling electronic components such as motors and DC-DC converters and for air conditioning. Main radiator (FC main radiator), electric vehicle radiator (EV radiator) and the like are installed to ensure the required cooling performance.

  In a fuel cell vehicle, if long-distance climbing or long-distance high-speed driving that is full power operation continues, units such as a fuel cell converter, various inverters, and an air compressor may generate heat and continue to be in a high temperature state. In order to prevent a function stop or output decrease due to overheating, it is necessary to provide a large radiator having sufficient cooling performance, a sub-radiator for assisting the main radiator, or the like.

  Therefore, Patent Document 1 uses a mounting frame attached to the outside of a vehicle floor panel to fix the fuel cell to the outside of the floor panel of the vehicle body so that the fuel cell main body and the mounting frame are in thermal contact with each other. A technique for cooling a fuel cell by an air-cooling and water-cooling mounting frame using an air flow is disclosed.

  In Patent Document 2, air is taken in by a cooling air path supplied to a fuel cell radiator located behind the front grille and a cowl top louver located between the bonnet and the windshield, and passes through the duct. There has been disclosed a technique for realizing a reduction in size of a radiator by providing a path for cooling air supplied to a radiator of a vehicle air conditioner independently of each other.

JP 2004-210176 A JP 2005-96706 A

  However, when a large fuel cell main radiator (FC main radiator), sub radiator (FC sub radiator), electric vehicle radiator (EV radiator), etc. are installed in the motor compartment behind the front grille, In the case of cooling by air whose temperature has increased and the temperature has been increased by heat exchange with another radiator, the cooling capacity may deteriorate. Such a radiator occupies the motor compartment and deteriorates the mountability of other parts, further deprives the design freedom, and deteriorates the aerodynamic performance.

  As in the air-cooled type or water-cooled / air-cooled system of Patent Document 1, the cooling power is insufficient only with natural traveling wind, and the cooling capacity may be insufficient when traveling on a long-distance slope. Although there is a technique for controlling a traveling wind by installing an FC sub-radiator under the floor of Patent Document 2, there is a case where aerodynamic characteristics are deteriorated.

  Therefore, an object of the fuel cell system according to the present invention is to provide a vehicle-mounted fuel cell system capable of efficiently cooling the fuel cell.

  In order to achieve the above object, the fuel cell system according to the present invention is cooled by the first radiator in order to vary the cooling capacity in the fuel cell system in which the fuel cell stack is mounted under the floor of the vehicle. A second radiator connected via a switching valve for further cooling the refrigerant, and airflow forming means for creating a flow of air around the second radiator, and the second radiator is under the floor of the vehicle The airflow forming means cools the second radiator by the airflow flowing along the vehicle central axis.

  Further, in the fuel cell system according to the present invention, the airflow forming means has a cooling fan behind the second radiator and forms a flow of air around the second radiator.

  Moreover, in the fuel cell system according to the present invention, the reaction water obtained from the gas-liquid separator that separates the reaction water condensed in the reaction gas is dropped on the second radiator by the dropping adjustment valve and cooled by the heat of vaporization. It is characterized by that.

  Further, the fuel cell system according to the present invention is characterized in that an introduction plate is provided for introducing running air to the second radiator from the lower end of the grille, cowl and bumper of the vehicle.

  Furthermore, in the fuel cell system according to the present invention, a cooling fin is provided in the fuel cell stack case in order to cool the fuel cell stack by the introduced traveling wind.

  In the fuel cell system according to the present invention, the “dynamic pressure effect” uses the combined wind of the airflow passing through the main radiator (running wind) and the airflow passing through the underfloor sub-radiator located in the center of the vehicle (running wind). This has the effect of enabling efficient cooling of the fuel cell.

1 is a configuration diagram showing a configuration of a vehicle having a fuel cell system according to a first embodiment of the present invention. It is a block diagram which shows the structure of the fuel cell system which concerns on this embodiment. It is explanatory drawing explaining the purge module which dripping the reaction water produced | generated with the fuel cell which concerns on this embodiment to a sub radiator. It is the figure shown from the vehicle bottom face side, and is explanatory drawing explaining the flow of the cooling wind which flows around the fuel cell system which concerns on 1st Embodiment. It is the figure shown from the vehicle front side, and is explanatory drawing explaining the flow of the cooling air which flows around the fuel cell system which concerns on 1st Embodiment. It is a figure shown from the vehicle side surface side, and is explanatory drawing explaining the flow of the cooling wind which flows around the fuel cell system which concerns on 2nd Embodiment. It is the figure shown from the vehicle bottom face side, and is explanatory drawing explaining the flow of the cooling wind which flows around the fuel cell system which concerns on 2nd Embodiment. It is the figure shown from the vehicle front side, and is explanatory drawing explaining the flow of the cooling air which flows around the fuel cell system which concerns on 2nd Embodiment.

  Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings.

  FIG. 1 shows the configuration of a fuel cell vehicle 1 according to the first embodiment of the present invention. In the fuel cell vehicle 1 of FIG. 1, an EV radiator 16, an FC radiator 15, and a main radiator fan 13 are disposed at the front portion of the vehicle, and the main radiator fan 13 takes in traveling wind from a grille 21. The front part of the vehicle has a motor compartment in which a motor and a drive system for driving the vehicle are arranged. The traveling wind taken in by the main radiator fan 13 is a fuel cell case 10 mounted on the lower part of the vehicle floor and a hydrogen tank 12 at the rear. Will be led to.

  Another traveling wind is guided from a cowl top louver 23 provided between the hood 22 and the front window 28, and is guided to the fuel cell case 10 mounted on the lower part of the vehicle floor through the duct. A DC / DC converter 11 capable of releasing heat by air cooling fins 18 is disposed in front of the fuel cell case 10, and a sub-radiator 17 is disposed below the fuel cell case 10. Further, behind the fuel cell case 10, the air flow generated by the main radiator fan 13 and the traveling wind guided from the cowl top louver 23 are combined, and further, a sub-radiator that discharges air around the sub-radiator 17. A large amount of traveling wind can be taken in by the fan 14.

  FIG. 2 shows a fuel cell system 2. The fuel cell system 2 discharges a fuel cell FC radiator 15 for heat dissipation, a main radiator fan 13, a switching valve 24 for switching the flow of cooling water, the fuel cell stack 20, and water generated during power generation. The fuel cell case 10 that houses the purge module 19 having a discharge valve that drops onto the sub-radiator 17, the sub-radiator 17, and the sub-radiator fan 14. The purge module 19 can be cooled by heat of vaporization by dropping reaction water onto the sub-radiator 17.

  In the fuel cell system 2 of FIG. 2, cooling water is circulated by the pump 42 in order to keep the operating temperature of the fuel cell appropriately. The cooling water discharged from the pump 42 is supplied to the FC radiator 15, and the cooling water is cooled by the FC radiator 15. The fuel cell control device (not shown) bypasses the sub-radiator 17 by the switching valve 24 when the operating temperature of the fuel cell stack 20 is low at the time of start-up or low-temperature driving, and the fuel cell control device from the FC radiator 15 Only the cooling water is supplied to the cooling path of the fuel cell stack 20. As a result, it can cope with extremely low temperatures that are below freezing.

  When the fuel cell stack 20 is operating at a high temperature, such as when traveling at high speed or traveling on a long-distance slope, the cooling water is supplied to the sub-radiator 17 by the switching valve 24, and the cooling water is additionally cooled. It is supplied to the cooling path of the fuel cell stack 20. Cooling water that has become hot when passing through the cooling path of the fuel cell stack 20 is sent to the FC radiator 15 by the pump 42. Further, when the fuel cell stack continues to be in a high temperature state, the fuel cell stack 20 continues to generate electricity and a large amount of reaction water is generated. Therefore, the reaction module is used by the purge module 19 to cool the vaporized heat. I do.

  FIG. 3 shows a purge module 19 having a discharge valve (drop adjusting valve) for dropping the reaction water generated by the fuel cell to the sub-radiator. The purge module 19 is disposed on the vehicle front side of the fuel cell case 10 and the sub-radiator 17 is disposed on the lower side with an inclination angle θ (for example, about 5 degrees), so that the reaction dropped by the purge module 19 is performed. The water will wet a wide area along the surface of the sub-radiator 17.

  The reaction water is separated by a gas-liquid separator and is usually sent to an exhaust pipe and discharged outside the vehicle. When the fuel cell is operating at high temperature and full power, such as during high-speed driving or long-distance hill driving, a large amount of reaction water is generated with power generation, and a large amount of reaction water is discharged from the exhaust pipe to the outside of the vehicle. Therefore, in the present embodiment, the reaction water is dropped by the purge module 19 according to the operating temperature of the fuel cell, and the sub-radiator 17 can be efficiently cooled by the heat of vaporization, thereby making it possible to reduce the size of the sub-radiator. .

  FIG. 4 shows the flow of cooling air flowing around the fuel cell system from the vehicle bottom side. One of the features in the present invention is that cooling is efficiently performed by a combined wind of running wind management and underfloor ventilation management by the sub-radiator fan 14.

  As shown in FIG. 4, a front under cover 33 having a plurality of wind guide fins (wind guide plates) 38 and 39 is provided under the floor of the fuel cell vehicle 1, and a plurality of slits for ventilation are provided in the wheel house liner 37. 36 is provided to discharge part of the traveling wind that has passed through the FC radiator 15. A fuel cell case 10 is disposed at the center of the vehicle, a sub radiator 17 is disposed below the fuel cell case, and a sub radiator fan 14 is disposed behind the fuel cell case 10.

  FIG. 5 shows the flow of cooling air flowing around the fuel cell system from the front side of the vehicle. The traveling wind introduced into the sub-radiator 17 under the floor is taken from the following three directions. The first is the traveling wind that enters from the motor compartment through the grill 21, the cowl top louver 23, the lower end of the bumper 26, etc., and the second traveling wind enters the turbulent flow with the rotation of the tire from the front wheel part. Air coming. Further, the third traveling wind is air entering from the under cover and the lower surface of the front bumper 26. Of the three-direction traveling winds, the air that enters from the first motor compartment is air that has passed through the FC radiator 15 and the EV radiator 16, and thus becomes relatively hot. It is possible to increase the cooling capacity by increasing the air volume. Furthermore, in order to reduce ventilation resistance due to obstacles, aerodynamic performance is improved and fuel efficiency is improved by actively sucking out air under the floor.

  Next, a second embodiment will be described. In the present embodiment, the running wind of the main radiator fan 13 that has become relatively high is not used for cooling the sub-radiator 17, but the running wind that passes through the sub-radiator 17 is generated by passing the vicinity and generating the draft wind. It is to increase.

  FIG. 6 shows the flow of cooling air flowing around the fuel cell system from the side of the vehicle. As shown in FIG. 6, the DC / DC converter 11 is disposed in the center tunnel 27, the fuel cell case 10 is disposed under the floor of the front seat 25, the sub-radiator 17 is disposed below the fuel cell case 10, and led to the rear end of the suspension undercover 34. A wind fin 38 is added, and a wind guide fin 39 is also provided in the FC under cover 35.

  As shown in FIG. 6 (A), the characteristic feature of this embodiment is that the traveling wind of 17 to the sub-radiator flowing through the vehicle central axis is generated from the lower surface of the cowl top louver 23, the FC under cover 35, and the front under cover 33. The cooling effect is further enhanced by mainly using the incoming traveling wind. Further, as shown in FIG. 6 (B), the relatively high temperature running wind that has passed through the main radiator fan 13 is discharged from the slit of the wheel house liner 37 using the turbulent flow of the front tire 31 and the FC under cover. Air that is discharged downward and rearward from both sides under the vehicle floor by the air guide fins 39 provided on the vehicle 35 is discharged by the “dynamic pressure effect” generated by the flow of the traveling wind and the wind of the sub radiator fan 14. The effect is improved.

  FIG. 7 shows the flow of cooling air flowing around the fuel cell system from the vehicle bottom side. As shown in FIG. 7, ventilation slits are added before and after the wheel house liner 37 so that the relatively high temperature of the main radiator fan 13 flows from the slits at the rear of the hall house along the side of the vehicle. Therefore, the sub radiator 17 is hardly affected. In addition, aerodynamic loss around the tire is reduced by using the turbulent flow generated around the front tire 31 to flow other traveling winds to the rear of the vehicle. Furthermore, a part of the traveling wind is concentrated near the center of the vehicle by the wind guide fins 38 and 39 for the under cover and the wind guiding effect that applies the force of the sub radiator fan 14 to the traveling wind to increase the flow of the wind under the floor. Is done.

  FIG. 8 shows the flow of cooling air flowing around the fuel cell system from the front side of the vehicle. By pulling the traveling wind to the rear of the vehicle by the sub radiator fan 14, the ventilation resistance in the motor compartment can be reduced, so that the aerodynamic performance can be suppressed from being lowered even if the front opening is increased due to the enlargement of the FC radiator. It becomes possible. Further, by making such a flow of traveling wind, it is possible to cool the DC / DC converter 11, the fuel cell case 10, and the sub-radiator 17 efficiently.

  The cooling method of the fuel cell system according to the present invention can be suitably applied to a fuel cell vehicle because the fuel cell can be cooled by the sub-radiator and the sub-radiator fan provided at the lower part of the fuel cell. is there.

  DESCRIPTION OF SYMBOLS 1 Fuel cell vehicle, 2 Fuel cell system, 10 Fuel cell case, 11 DC / DC converter, 12 Hydrogen tank, 13 Main radiator fan, 14 Sub radiator fan, 15 FC radiator, 16 EV radiator, 17 Sub radiator, 18 Air cooling fin , 19 Purge module, 20 Fuel cell stack, 21 Grill, 22 Hood, 23 Cowl top louver, 24 Switching valve, 25 Front seat, 26 Bumper, 27 Center tunnel, 28 Front window, 31 Front tire, 33 Front under cover, 34 Suspension under cover, 35 FC under cover, 36 slits, 37 wheel house liner, 38, 39 wind guide fins, 42 pump.

Claims (5)

In a fuel cell system in which a fuel cell stack is mounted under the floor of a vehicle,
A second radiator connected via a switching valve for further cooling the refrigerant cooled by the first radiator in order to vary the cooling capacity;
Airflow forming means for creating a flow of air around the second radiator;
Have
The second radiator is disposed at the bottom of the fuel cell stack mounted under the floor of the vehicle,
The fuel cell system, wherein the airflow forming means cools the second radiator by an airflow flowing along the vehicle central axis. The fuel cell system according to claim 1, wherein
The air flow forming means has a cooling fan at the rear of the second radiator and forms a flow of air around the second radiator. The fuel cell system according to claim 1 or 2,
A fuel cell system, wherein reaction water obtained from a gas-liquid separator that separates reaction water condensed in a reaction gas is dropped onto a second radiator by a dropping adjustment valve and cooled by heat of vaporization. The fuel cell system according to any one of claims 1 to 3,
A fuel cell system, characterized in that an introduction plate for introducing traveling wind from the lower end of a vehicle grill, cowl and bumper to the second radiator is provided. The fuel cell system according to any one of claims 1 to 4,
A fuel cell system, wherein a cooling fin is provided in a fuel cell stack case in order to cool the fuel cell stack with the introduced traveling wind.

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