JP4042659B2 - Fuel cell vehicle - Google Patents

Description

  The present invention relates to a fuel cell vehicle equipped with a fuel cell.

  Fuel cells are attracting attention as a power source for moving bodies such as automobiles. One of the most promising fuel cells for mobile objects is a polymer electrolyte membrane (hereinafter referred to as PEM) type fuel cell (hereinafter referred to as PEFC) operated at a relatively low temperature of around 80 ° C. Called).

  PEFC uses hydrogen as a fuel gas to extract electricity through a reaction with an oxidizing gas (usually oxygen). Hydrogen from the fuel gas electrode becomes protons and moves through the PEM to the oxidizing gas electrode to react with the oxidizing gas. Because of this mechanism, the PEM needs to be moist and the air supplied to the PEFC may have to be humidified.

  In a system that generates hydrogen, which is a fuel gas of PEFC, by reforming, water may be required for the reforming reaction.

Briefly explaining the reforming reaction, reforming is to generate hydrogen from liquid fuel such as gasoline, water, air or the like. The reaction formulas of the steam reforming reaction and the partial oxidation reaction are shown below.
(Steam reforming reaction) C _n H _m + nH ₂ O⇒nCO + (m / 2 + n) H ₂
(Partial oxidation _{reaction) C n H m + (n} / 2) O 2 ⇒nCO + (m / 2) H 2
As for oxygen necessary for the partial oxidation reaction, air is often used for moving bodies. An autothermal (ATR) reaction that combines a steam reforming reaction that is an endothermic reaction and a partial oxidation reaction that is an exothermic reaction is also known.

In the formulas shown above, hydrocarbons (C _n H _m ) such as octane C ₈ H ₁₈ are used as the reforming raw fuel, but those containing other than carbon atoms and hydrogen atoms such as methanol CH ₃ OH are also included. It can be a raw fuel.

CO (carbon monoxide) produced | generated above becomes a raw material of the following shift reactions.
(Shift reaction) CO + H ₂ O⇔CO ₂ + H ₂
Since CO that has not been reduced by the shift reaction may deteriorate the PEM, it may be converted to carbon dioxide using a catalyst that selectively oxidizes CO.

  That is, water is required for the steam reforming reaction or the shift reaction.

  As a conventional fuel cell system using a reforming reaction, a cooling circuit of a radiator or an air conditioning system is connected to a fuel cell system through a heat exchanger in order to obtain water for operation of the fuel cell in an automobile. There exists a structure couple | bonded with an exhaust gas flow (refer patent document 1).

  Further, in order to provide a humidifier capable of uniformly distributing the gas flow rate and controlling the humidification capacity as required, a plurality of hollow fiber membranes are provided in a housing, and two gases having different moisture contents are In a humidifier that exchanges the moisture between the two gases by flowing through the outer and inner sides of the hollow fiber membrane through a plurality of openings provided in the housing, at least one of the openings The portion is formed by a plurality of holes, and among the plurality of holes, a hole near the entrance / exit portion where any one of the gases is introduced into and led out from the housing is small, and a far hole is formed large, A second inlet / outlet portion where any one of the gases is introduced into and led out from the housing at a position where the near hole is large and the far hole is small, facing the inlet / outlet portion across the axis of the casing. And at least one of the entry / exit part and the second entry / exit part Select Write, there is a technique of providing a switching means to flow through one of the gas (see Patent Document 2).

In addition, in order to avoid the complexity of the system for heating and humidifying operation with the total heat exchanger, the indoor coil and the humidifier, heat exchange is performed on the exhaust gas used as part of the air electrode exhaust using a three-way valve. There is a technique for adjusting the balance between the amount of heat received and moisture by controlling the flow rate to the inflow gas into the exhaust gas and the exhaust gas into the exhaust gas discharge (see Patent Document 3).
JP 2001-238991 A JP 2002-66265 A JP 2002-5478 A

  However, in the first conventional example, the water is obtained by condensing the water contained in the exhaust gas from the fuel cell system using a radiator. However, in order to obtain water by condensing the water vapor, the water is obtained from the water vapor. It is necessary to take a large amount of heat, and the heat radiation load of the radiator increases. In order to respond to a large heat radiation load, it is necessary to increase the size of the radiator or use a powerful radiator fan motor. However, increasing the size of the radiator has the problems of deteriorating layout and taking away the freedom of vehicle design. It was.

  The second conventional example uses a hollow fiber membrane as a moisture recovery device (hereinafter referred to as WRD) capable of exchanging moisture between gas and gas without using heat radiation by a cooling device.

  The principle of water separation by this hollow fiber membrane will be explained as follows. That is, when the wet gas is passed through the inside of the hollow fiber membrane, the vapor pressure is reduced in the capillary of the hollow fiber membrane, so that water vapor is condensed in the capillary and becomes condensed water. This condensate is sucked out by capillary action and permeates the dry gas flowing through the outside of the hollow fiber membrane and utilizes the capillary action of the hollow fiber membrane. The process of condensing the water vapor of the wet gas flowing inside the hollow fiber membrane in the capillary is thermodynamically the same as the water vapor condensation of the first conventional example, and therefore the heat of condensation is radiated by some means. There is a need.

  Therefore, the lower the temperature of the dry gas outside the hollow fiber membrane, the more moisture can be transferred from the wet gas inside the hollow fiber membrane to the dry gas outside. In other words, it is desirable that the outside air, which is a dry gas, is low in temperature with respect to the fuel cell exhaust gas, which is a wet gas. If the outside air temperature is high, there is a possibility that sufficient moisture transfer cannot be expected.

  In the third conventional example, the heat and moisture of the exhaust of the fuel cell are used to heat the room, and the heat and moisture are not used for the operation of the fuel cell. Even if this conventional example is applied and the exhaust of the fuel cell is used as the oxidizing gas of the fuel cell, the oxygen contained in the exhaust of the fuel cell is reduced because it is used for power generation of the fuel cell. It is clear that the fuel cell cannot be operated efficiently.

  In view of the above problems, an object of the present invention is to provide a fuel cell vehicle that efficiently supplies oxygen and moisture to a fuel cell using heat and moisture of exhaust gas.

  In the fuel cell vehicle, the present invention relates to a fuel cell, an air conditioner for controlling the interior of the vehicle interior to a predetermined temperature, and an inflow air flowing into the fuel cell and flowing out from the fuel cell, respectively, on both surfaces of the water permeable membrane A heat exchanger that exchanges heat with the exhausted air, and the heat exchanger includes air in the vehicle interior or air exhausted from the vehicle interior when the air conditioner is operated in the outside air introduction mode, or the At least one of the air in the air conditioner is taken in as the inflow air, condensed by heat exchange between the inflow air and the exhaust air, and the inflow air is made up of moisture in the exhaust air that has passed through the water permeable membrane. Humidify.

  At least one of the air exhausted from the vehicle interior or the air in the air conditioner when the air in the vehicle interior or the air conditioner is operated in the outside air introduction mode is introduced into the heat exchanger to exchange heat with the exhaust air of the fuel cell. Therefore, the heat and moisture of the exhaust air discharged from the fuel cell can be efficiently recovered, the thermal efficiency of the fuel cell vehicle can be improved, and the water shortage of the fuel cell can be prevented.

  FIG. 1 shows the configuration of a fuel cell system to which the present invention is applied.

  The fuel cell 1 as a vehicle power supply source generates power using the supplied hydrogen and oxygen, supplies the generated power to a drive motor (not shown), and the drive motor rotates the drive wheels of the vehicle to travel the vehicle. Let

  The operation of the fuel cell system including the fuel cell 1 is integrated and controlled by the controller 2, and the controller 2 is connected to an air conditioning controller 3 that controls the air conditioning device of the vehicle. The air conditioning controller 3 performs control of air introduced into the vehicle interior of the vehicle and operation control of the air conditioning compressor 5 based on the control signal of the controller 2, for example.

  Air taken into the fuel cell 1 as an oxidizing gas is sent to the fuel cell 1 via an entropy recovery device (hereinafter referred to as ERD) 6. Here, the ERD is formed by a thin sheet of water-permeable foam metal to form a passage through which air flowing into the ERD 6 circulates and a passage through which exhaust air discharged from the fuel cell 1 circulates. The air (exhaust) can exchange heat.

  In solid polymer membrane fuel cells, the exhaust temperature is usually around 80 ° C to 100 ° C, and the air taken in from the outside is usually at a lower outside air temperature. At the same time, moisture contained in the exhaust is condensed on the water-permeable foam metal plate and moves to the intake side.

  Therefore, as understood from the principle, the greater the temperature difference between the intake air and the exhaust gas, the easier the moisture in the exhaust gas is condensed, and more water moves from the exhaust gas to the intake air. Alternatively, if the intake air contains appropriate moisture in advance, the temperature difference between the intake air and the exhaust gas is relatively small, so that a large amount of water does not need to move from the exhaust gas to the intake air.

  The water that has moved to the intake side evaporates and is taken into the fuel cell 1 together with the intake air, and is used for humidification of the fuel cell 1.

  In addition, the steam reforming reaction typical of reforming reactions such as gasoline and methanol, and the autothermal reaction that balances the steam reforming reaction and partial oxidation reaction require water as the reforming raw material, so the fuel cell system Is provided with a fuel reforming fuel cell, the moisture taken together with the intake air as described above can be used for the reforming reaction.

  A controller 2 that performs integrated control of the fuel cell system performs switching of an intake port that controls introduction of intake air into the fuel cell 1 to be described later via an intake port switch 7. The mouths 7a to 7c are connected.

  Next, the structure of the air conditioning unit 8 provided with the air inlet, the intake door, and the air conditioning compressor will be described with reference to FIG.

  The air conditioning unit 8 includes an intake door 4 that adjusts a mixing ratio between outside air introduced from outside the air introduced into the air conditioning unit 8 and inside air circulating in the vehicle interior, and dust or dust of the mixed air. A clean filter 10 to be removed, a compressor 5 that pumps air into the passenger compartment, an evaporator (cooling device) 12 that cools the air sent by the compressor 5, and a heater core 13 that heats the air cooled by the evaporator 12 to a predetermined temperature And an air mix door 14 and a MAX-COOL door 15 for mixing the air cooled by the evaporator 12 and the air heated by the heater core 13 to adjust to a predetermined temperature. Here, the air mix door 14 is installed upstream of the heat core 13.

  The temperature-adjusted air passes through the differential door 16 that controls the amount of air blown into the vehicle interior from the defroster outlet and the vent door 17 that controls the amount of air blown into the vehicle compartment from the ventilator outlet or the foot outlet. It is blown into the room. Predetermined conditions are set by the driver and the controller 3 for the load of the compressor 4, the setting of the predetermined temperature, and the air blowing destination.

  Further, the air conditioning unit 8 is provided with an air inlet for introducing air into the ERD 6. The intake port is integrally formed in the vicinity of the internal air intake 18 that takes in the air in the vehicle interior into the air conditioning unit 8, the first air intake port 7 a for introducing the air in the vehicle interior to the fuel cell 1, the evaporator 12, and the air mix door. 14 is formed between the second air inlet 7b for introducing the coolest air in the air conditioning unit 8 to the ERD 6, and part of the air in the vehicle compartment is discharged to the outside when the air conditioning unit is operated in the outside air mode. And a third air inlet 7c that introduces air exhausted from the passenger compartment into the ERD 6. Air directed from the first to third intake ports 7a to 7c toward the fuel cell 1 is limited by the intake port switch 7 and is supplied to the ERD 6 according to the operating conditions.

  Since the first air inlet 7a is integrally formed in the vicinity of the inside air inlet 18, air can be introduced into the ERD 6 by a simple method.

  Since the second intake port 7b takes in air from the downstream side of the compressor 5, the pressurized air can be supplied to the ERD 6, and air can be supplied to the fuel cell with relatively little energy. Moreover, since the 2nd inlet 7b takes in air from the downstream of the evaporator 12, it can send the cooled air into ERD6, can enlarge a temperature difference with exhaust, and can heat-exchange more efficiently.

  Here, considering heat exchange in the ERD 6, heat exchange and water condensation are promoted as the temperature difference between the intake air and the exhaust air increases, so that the second intake air is directly downstream of the evaporator 12 where the temperature of the air is the lowest. It is desirable to install the mouth 7b.

  FIG. 3 is a view for explaining the configuration of the third air inlet 7 c, and an opening 22 through which air in the vehicle compartment is discharged is formed integrally with the interior trim 23. The third air inlet 7c is formed integrally with an interior trim 23 formed with an opening 22 through which air in the vehicle compartment is taken. A rear intake door 24 is installed in the interior trim 23, and air is supplied to the drafter and the ERD 6 at a predetermined ratio depending on the opening degree of the rear intake door 24. Here, the rear intake door 24 also functions to prevent air from flowing back into the vehicle interior from the outside. The rear intake door 24 is used when air in the vehicle interior is supplied to the ERD 6 from the first air inlet 7a. Control is performed so that outside air does not flow back into the passenger compartment. The third intake port 7c is formed integrally with the interior trim 23, but may be provided integrally on the outer plate of the vehicle body.

  Since the third air inlet 7c is formed integrally with the interior trim 23, air can be supplied to the ERD 6 by a simple method. Note that the same effect can be obtained when it is formed integrally with the outer plate. Further, since the third intake port 7 c is formed upstream of the rear intake door 24, it is possible to prevent the outside air from flowing back to the fuel cell 1.

  Closing the rear intake door 24 also has an effect that the outside air does not flow back into the vehicle interior when air in the vehicle interior is supplied from the first air inlet 7a to the ERD 6.

  FIG. 4 is a flowchart illustrating an example of intake port switching control.

  First, in step 1 (shown as S1 in the figure), it is determined whether or not the change in the required load of the vehicle is greater than or equal to the first predetermined fluctuation amount L1. The required load of the vehicle can be calculated based on at least one of the actual vehicle speed (or estimated vehicle speed), the actual fuel cell output, and the required output (or estimated output) of the fuel cell based on the accelerator pedal opening. If it is equal to or smaller than the first predetermined fluctuation amount L1, the control is terminated. In step 2, the outside air temperature and the vehicle interior temperature are read from a sensor (not shown). For example, when the vehicle interior temperature is higher than the outside air temperature as in winter, the humidity in the vehicle interior is high due to the expiration of the occupant. Since it is considered that the amount of water is high, control proceeds to step 3 so that air is introduced into the ERD 6 from the third air inlet 7c.

  On the other hand, when the vehicle interior temperature is equal to or lower than the outside air temperature, the process proceeds to step 4 to determine whether or not the required load fluctuation is equal to or larger than the second predetermined fluctuation amount L2 (L2> L1 here). If it is greater than or equal to L2, the process proceeds to step 5, and if smaller than L2, the process proceeds to step 6. In step 6, since the vehicle interior temperature is lower than the outside air temperature, control is performed so that air is introduced into the ERD 6 from the first air inlet 7a.

  In step 5, it is determined whether the compressor 4 is operating. If it is in operation, the process proceeds to step 7; otherwise, the process proceeds to step 8 and the compressor 4 is operated to proceed to step 7. In step 7, control is performed so that air is introduced into the ERD 6 from the second air inlet 7b. Since the air introduced into the ERD 6 from the second air inlet 7b is the coldest air in the air conditioning unit 8, the temperature difference at the time of heat exchange with the exhaust at the ERD 6 becomes large, and heat transfer and water condensation are efficient. Can be done well.

  FIG. 5 is a flowchart relating to the circulation rate and the air volume adjustment of the compressor. Here, the circulation rate is an air flow rate that circulates through the passenger compartment among the air flow rate supplied to the air conditioning unit, and the outside air increases by reducing the circulation rate.

  First, at step 11, as in step 1, it is determined whether or not the required load fluctuation is larger than the first predetermined fluctuation amount L1. If it is equal to or smaller than the first predetermined fluctuation amount L1, the control is terminated.

  In step 12, the air flow rate to the fuel cell 1 is controlled according to the load fluctuation amount. If the load fluctuation amount is equal to or smaller than the third predetermined fluctuation amount L3 larger than L1, the process proceeds to step 14. If the load fluctuation amount is greater than L3 and less than or equal to a fourth predetermined fluctuation amount L4 that is greater than L3, the process proceeds to step 13, the air volume from the compressor 4 is increased and the process proceeds to step 14, and the circulation rate is decreased in step 14. Increase outside air. If the load fluctuation amount is larger than L4, the process proceeds to step 15 and control is performed so that all the air flow rates of the air conditioning unit 9 are introduced into the fuel cell 1.

  Therefore, in the present invention, exhaust of the fuel cell is introduced into the heat exchanger (ERD6), and at least one of the air in the vehicle interior, the air exhausted from the vehicle interior, or the air in the air conditioner is used as the heat exchanger ( ERD6). As a result, heat exchange with the exhaust of the fuel cell is promoted, moisture in the exhaust is condensed, and the condensed water passes through the water permeable membrane in the heat exchanger to increase the humidity of the air, thereby increasing the humidity. The air is supplied to the fuel cell.

  In addition, since there are a plurality of intake ports for sending air to the heat exchanger and the intake ports are selected according to the vehicle operating conditions, the temperature suitable for the fuel cell operating conditions required from the vehicle operating conditions Humid air can be supplied to the fuel cell.

  Further, when the intake port is switched in accordance with the driving conditions of the vehicle, the driving conditions of the air conditioner (air conditioning unit 8) are changed, so that passenger comfort is not impaired.

  Since the operating condition of the air conditioner is at least one of the air circulation rate and the air volume in the passenger compartment, it is possible to achieve both the amount of air taken in by the fuel cell and the amount of air required for the air conditioner.

  The vehicle operating condition is at least one of the actual vehicle speed, estimated vehicle speed, actual fuel cell output, required fuel cell output, and estimated fuel cell output. Can be done.

  The fuel cell vehicle to which the present invention is applied can prevent thermal efficiency and moisture shortage of the fuel cell, and can be used for a long-distance traveling vehicle or the like.

It is a block diagram of the fuel cell system of this invention. It is explanatory drawing of the air conditioning unit of this invention. It is explanatory drawing of the drafter part of the air-conditioning unit of this invention. It is a flowchart explaining intake-port switching control. It is a flowchart explaining the control of a circulation rate and air flow rate switching.

Explanation of symbols

1 Fuel Cell 2 Controller 3 Air Conditioning Controller 4 Intake Door 5 Air Conditioning Compressor 6 ERD
7 Intake port switching devices 7a to 7c 1st to 3rd intake ports 8 Air conditioning unit 10 Clean filter 12 Evaporator 13 Heater core 14 Air mix door 15 MAX-COOL door 16 Differential door 17 Vent door 18 Inside air inlet 22 Opening 23 Interior trim 24 Rear intake door

Claims (15)

A fuel cell that generates electricity using hydrogen and air;
An air conditioner for controlling the passenger compartment to a predetermined temperature;
A heat exchanger that exchanges heat between the inflow air flowing into the fuel cell and the exhaust air flowing out of the fuel cell, which circulates on both sides of the water permeable membrane,
In a fuel cell vehicle equipped with
The heat exchanger takes in at least one of air in the vehicle interior or air discharged from the vehicle interior when the air conditioner is operated in the outside air introduction mode or air in the air conditioner as the inflow air,
A fuel cell vehicle characterized in that the inflowing air is humidified with moisture in the exhausted air that is condensed by heat exchange between the inflowing air and the exhausted air and that has passed through the water permeable membrane.   The intake port according to claim 1, wherein an intake port for taking in air in the vehicle compartment into the fuel cell is provided integrally with the air conditioner in the vicinity of an intake port for the inside air circulating in the vehicle compartment of the air conditioner. The fuel cell vehicle described.   3. The fuel cell vehicle according to claim 1, wherein an intake port for taking in air discharged from the passenger compartment into the fuel cell is provided integrally with an interior member. 4.   3. The fuel cell vehicle according to claim 1, wherein an intake port for taking in air discharged from the passenger compartment into the fuel cell is provided integrally with an outer plate. 4.   The intake port for taking in the air discharged from the passenger compartment into the fuel cell is provided with backflow prevention means for preventing outside air from flowing back into the passenger compartment. The fuel cell vehicle according to one.   6. The fuel cell vehicle according to claim 5, wherein when the air in the vehicle interior is taken into the fuel cell, the backflow prevention means prevents backflow of outside air into the vehicle interior. The air conditioner includes a filter for purifying air,
The fuel cell vehicle according to claim 1, wherein an intake port for taking air into the fuel cell from the air conditioner is provided downstream of the filter. The air conditioner includes a blower that pumps air into the passenger compartment,
The fuel cell vehicle according to claim 1 or 7, wherein an intake port for taking air into the fuel cell from the air conditioner is provided downstream of the blower. The air conditioner includes a cooling device for cooling air,
The fuel cell vehicle according to claim 1, wherein an intake port for taking air into the fuel cell from the air conditioner is provided downstream of the cooling device. The air conditioner includes an air mix door that adjusts the temperature of air into the passenger compartment.
10. The fuel cell vehicle according to claim 9, wherein an intake port for taking air into the fuel cell from the air conditioner is provided downstream of the cooling device and upstream of the air mix door.   An air intake for taking in the air in the vehicle interior or the air discharged from the vehicle interior when the air conditioner is operated in the outside air introduction mode or the air in the air conditioner into the fuel cell is provided. The fuel cell vehicle according to any one of claims 1 to 9, wherein the fuel cell vehicle is selected according to the driving conditions.   The fuel cell vehicle according to claim 11, wherein the operating condition of the air conditioner is changed according to the operating condition of the vehicle.   13. The fuel cell vehicle according to claim 12, wherein the operating condition of the air conditioner is at least one of an air circulation rate and an air volume into the passenger compartment. The air conditioner includes a blower that pumps air into the passenger compartment,
The fuel cell vehicle according to claim 12, wherein the operating condition of the air conditioner is an operating state of the blower. 12. The fuel cell according to claim 11, wherein the driving condition of the vehicle is at least one of an actual vehicle speed, an estimated vehicle speed, an actual output of the fuel cell, a required output of the fuel cell, and an estimated required output of the fuel cell. vehicle.

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