JP2008112631A - On-vehicle fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an on-vehicle fuel cell system capable of suitably securing an oxygen volume needed for securing required power generation amount. <P>SOLUTION: The on-vehicle fuel cell system is provided with a fuel cell stack 13 for generating power by being supplied with hydrogen gas and air, a compressor 14 for supplying air to the fuel cell stack 13, a control device 15 controlling driving of the compressor 14, and a sensor 16 for detecting the open air pressure. The control device 15 calculates the number of revolutions of the compressor 14, based on the required power generation amount and the open air pressure detected by the sensor 16. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an in-vehicle fuel cell system.

  A fuel cell takes out electric power from between electrodes provided on both surfaces of an electrolyte by an electrochemical reaction of fuel gas such as hydrogen gas and air containing oxygen gas through the electrolyte. In particular, a polymer electrolyte fuel cell using a resin membrane (polymer membrane) as an electrolyte can be miniaturized and is easy to handle because it operates at a relatively low temperature of 100 ° C. or lower. Therefore, the polymer electrolyte fuel cell is expected as an in-vehicle fuel cell (see, for example, Patent Document 1). Here, in a fuel cell, an electrolyte sandwiched between a negative electrode and a positive electrode is referred to as a single cell, and a single cell sandwiched between separators is referred to as a stack. The fuel cell generates electric power when fuel gas and air are supplied to the stack. Note that fuel gas is supplied to the negative electrode, and air is supplied to the positive electrode. A compressor is used to supply air to the positive electrode.

In a fuel cell vehicle equipped with such a fuel cell system including an in-vehicle fuel cell, the amount of power generated by the fuel cell is changed based on the amount of depression of the accelerator to control the speed of the vehicle. That is, the control device that controls the compressor or the like controls the flow rate of air supplied to the stack by controlling the rotation speed of the compressor based on the accelerator depression amount.
JP 2006-179331 A

  However, the control device uniquely determines the rotation speed of the compressor with respect to the required power generation amount. For this reason, the required air flow rate, that is, the required oxygen flow rate cannot be obtained in a use environment in which the external air pressure is different from that at the time of initial setting. If the external pressure changes, the amount of oxygen contained per unit volume also changes. Even if the same air flow rate is supplied to the fuel cell stack, the oxygen flow rate contained in the fuel cell stack is small, so the oxygen flow rate supplied to the stack is small. If such a required amount of oxygen cannot be obtained, the driver may feel uncomfortable by not being able to obtain a speed corresponding to the amount of depression of the accelerator.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an in-vehicle fuel cell system that can suitably secure the amount of oxygen required to secure the required amount of power generation. There is.

Hereinafter, means for achieving the above-described object and its operation and effects will be described.
The invention described in claim 1 includes a fuel cell stack that generates electricity by being supplied with hydrogen gas and air, a compressor that supplies the air to the fuel cell stack, and a control device that drives and controls the compressor. An in-vehicle fuel cell system includes a sensor that detects an external air pressure, and the control device calculates a rotation speed of the compressor based on a required power generation amount and an external air pressure detected by the sensor. .

  According to this configuration, since the control device calculates the rotation speed of the compressor based on the external air pressure detected by the sensor, it is required even when the oxygen amount per unit volume changes with the change of the external air pressure. Rotational speed control of the compressor is performed so that an air flow rate necessary for securing the power generation amount is supplied to the fuel cell stack. That is, the oxygen supply amount per unit volume required to secure the required power generation amount is ensured. As a result, a necessary oxygen flow rate can be supplied to the fuel cell stack even in a use environment where the amount of oxygen contained in air per unit volume is different.

  According to a second aspect of the present invention, in the in-vehicle fuel cell system according to the first aspect, the control device defines a required power generation amount and a rotational speed of the compressor corresponding to an external air pressure detected by the sensor. The gist of the invention is to provide a memory storing a map, read out the rotational speed stored from the memory, and drive and control the compressor at the same rotational speed.

  According to this configuration, the controller reads out the compressor rotation speed corresponding to the required air volume and the external atmospheric pressure detected by the sensor from the memory, and calculates the compressor rotation speed in order to drive and control the compressor. It is possible to easily determine the rotation speed of the compressor as compared with the above.

  According to the present invention, it is possible to suitably secure the amount of oxygen required to secure the required power generation amount.

Hereinafter, an embodiment in which a vehicle-mounted fuel cell system according to the present invention is embodied in a fuel cell vehicle will be described with reference to FIGS.
FIG. 1 is a block diagram showing a configuration of a fuel cell vehicle. As shown in FIG. 1, the fuel cell vehicle is supplied through a fuel cell system 1 that generates power, an inverter 2 that converts DC power generated by the fuel cell system 1 into AC power, and an inverter 2. A motor 3 driven by AC power, a drive wheel 4 driven to rotate by the motor 3, a driven wheel 5, and an accelerator sensor 6 for detecting the accelerator depression amount of the driver are provided. The fuel cell system 1 includes a hydrogen tank 11 that stores hydrogen gas as fuel, a pressure regulating valve 12 that adjusts the pressure of the hydrogen gas supplied from the hydrogen tank 11, hydrogen gas to the negative electrode, and air to the positive electrode. , A fuel cell stack 13 for generating electric power, a compressor 14 for sending air to the fuel cell stack 13, a control device 15 for controlling the entire fuel cell system, and a sensor 16 for detecting the outside air pressure.

  Since the hydrogen gas supplied from the hydrogen tank 11 is filled in the hydrogen tank 11 at a high pressure, it is regulated by the pressure regulating valve 12 and supplied to the negative electrode of the fuel cell stack 13. The compressor 14 compresses air as an oxidant and supplies the compressed air to the positive electrode of the fuel cell stack 13. The control device 15 controls the pressure regulating valve 12 so that the pressure of the hydrogen gas supplied to the fuel cell stack 13 becomes the operating pressure. Further, the control device 15 receives the stepping amount from the accelerator sensor 6 and receives the external atmospheric pressure detected by the sensor 16. When receiving the depression amount signal from the accelerator sensor 6, the control device 15 calculates the required power generation amount according to the depression amount. And the control apparatus 15 calculates | requires the optimal rotation speed from the required electric power generation amount and the external atmospheric pressure which the sensor 16 detected based on the map of the required electric power generation amount and rotation speed set for every external atmospheric pressure memorize | stored in the memory 15a. The compressor 14 is driven and controlled so as to have the same rotational speed. Then, the control device 15 drives the drive wheels 4 by controlling the motor 3 through the inverter 2.

  Next, the control mode of the fuel cell system will be described with reference to FIGS. FIG. 2 is a map showing the required rotational speed with respect to the required power generation amount for each external air pressure detected by the sensor 16. The flowchart of FIG. 3 is executed by the control device 15 based on the control program stored in the memory 15a.

  As shown in FIG. 3, the control device 15 starts the compressor 14 when detecting the depression of the accelerator from the accelerator sensor 6. The control device 15 calculates the required power generation amount based on the depression amount from the accelerator sensor 6. Next, the control device 15 acquires the value of the external air pressure from the sensor 16 (step S10), and based on the oxygen flow rate (required oxygen flow rate) required to generate the required power generation amount and the acquired external air pressure, FIG. The required number of revolutions is calculated from the map shown in FIG. 2 (step S20). The control device 15 drives and controls the compressor 14 so that the calculated rotation speed is achieved (step S30). For example, when the outside air pressure in a lowland and highland is different, even if the amount of oxygen per unit volume is different due to the different outside air pressure, the air flow rate is changed by controlling the rotation speed of the compressor 14 according to the outside air pressure. The amount of oxygen required for the required power generation can be secured. And the control apparatus 15 judges whether there exists any stop command which stops the compressor 14 (step S40). Here, when there is no stop command (step S40: YES), the above steps S10 to S30 are repeated. On the other hand, when there is a stop command (step S40: NO), the compressor 14 is stopped.

As described above, according to the embodiment described above, the following effects can be obtained.
(1) Since the controller 15 calculates the rotation speed of the compressor 14 based on the external air pressure detected by the sensor 16, it is required even if the oxygen amount per unit volume changes with the change of the external air pressure. The rotation speed control of the compressor 14 is performed so that the air flow rate necessary for securing the power generation amount is supplied to the fuel cell stack 13. That is, the oxygen supply amount per unit volume required to secure the required power generation amount is ensured. As a result, a necessary oxygen flow rate can be supplied to the fuel cell stack 13 even in a usage environment where the amount of oxygen contained in air per unit volume is different.

  (2) The controller 15 reads out the rotational speed of the compressor 14 corresponding to the required air amount and the external air pressure detected by the sensor 16 from the memory 15a, and controls the rotational speed of the compressor 14 to drive and control the compressor 14. The number of rotations of the compressor 14 can be easily determined as compared with that of the compressor.

In addition, the said embodiment can be implemented with the following forms which changed this suitably.
In the above embodiment, the control device 15 calculates the rotation speed of the compressor 14 from the map stored in the memory 15a. However, the control device 15 may perform calculation processing based on the required power generation amount and the detected external air pressure. Good.

The block diagram which shows the structure of a fuel cell. The figure which shows the relationship between required electric power generation amount and rotation speed. The flowchart which shows the control aspect of a control apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell system, 2 ... Inverter, 3 ... Motor, 4 ... Drive wheel, 5 ... Driven wheel, 6 ... Accelerator sensor, 11 ... Hydrogen tank, 12 ... Pressure regulating valve, 13 ... Fuel cell stack, 14 ... Compressor, 15 ... control device, 15a ... memory, 16 ... sensor.

Claims (2)

In an in-vehicle fuel cell system comprising a fuel cell stack that generates electricity by being supplied with hydrogen gas and air, a compressor that supplies the air to the fuel cell stack, and a control device that drives and controls the compressor.
Equipped with a sensor to detect the atmospheric pressure,
The said control apparatus calculates the rotation speed of the said compressor based on the required electric power generation amount and the external atmospheric pressure which the said sensor detected. The vehicle-mounted fuel cell system characterized by the above-mentioned. The in-vehicle fuel cell system according to claim 1,
The control device includes a memory that stores a map that defines a rotation speed of the compressor corresponding to a required power generation amount and an external air pressure detected by the sensor, reads the rotation speed stored from the memory, and performs the rotation An on-vehicle fuel cell system, wherein the compressor is driven and controlled by a number.

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