JP2008243563A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make the reduction of the number of components compatible with an improvement in supply reliability, in a fuel cell system supplying fuel gases by a plurality of high-pressure tanks. <P>SOLUTION: In a fuel-cell vehicle 10, all main stop valves 24, 26, 28 and 30 are opened in operation, and hydrogen gases stored in the high-pressure tanks 16, 18, 20 and 22 are supplied to a fuel cell 46 through a confluent passage 40. The fuel cell 46 generates power according to the supplied hydrogen gases. An electric control part 50 calculates electric energy generated in a predetermined period, and the pressure variation of the confluent passage 40 in the period, and transmits a control signal instructing the main stop valves 24, 26, 28 and 30 to open the valves again by determining that there is a valve having caused a malfunction when the pressure variation is larger than a predicted valve. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell system that receives a supply of fuel gas from a high-pressure tank, and more particularly to a technique for managing the supply of fuel gas.

  In some cases, fuel gas is supplied from a plurality of high-pressure tanks to the fuel cell. Patent Document 1 below discloses a technique in which high-pressure tanks storing hydrogen are divided into a plurality of groups, and the on-off valves of the high-pressure tanks belonging to the same group are simultaneously controlled to open and close. The purpose of this technique is to reduce the number of parts for control and to improve the variation in the frequency of use of the high-pressure tank.

  In addition, the following patent documents 2 and 3 can be mentioned as literature regarding the fuel gas supply from a high pressure tank. Patent Document 2 below discloses a technique for determining an abnormality of a shutoff valve provided in a flow path for supplying fuel gas based on the state of the fuel gas upstream and downstream thereof. Specifically, the abnormality is determined when the upstream and downstream pressures deviate from predetermined conditions. Patent Document 3 below discloses a technique for performing a fuel gas leak check in a flow path to which a plurality of high-pressure tanks are connected. In this technique, since a leak check gas is supplied to the pipe for inspection, it is not necessary to fill each high pressure tank with fuel gas.

JP 2005-226715 A JP 2002-372197 A JP 2006-210055 A

  As in the technique of the above-mentioned Patent Document 1, when simultaneously opening a plurality of high-pressure tank opening / closing valves, fuel gas is supplied even if some of the high-pressure tank opening / closing valves are not opened. The malfunction of the on-off valve cannot be detected directly. However, if a sensor for detection is attached to each on-off valve in order to check whether all the on-off valves to be opened are open, there is a problem that the number of parts increases. This is the same even when the on-off valve is manually opened. In addition, the techniques described in Patent Documents 2 and 3 cannot cope with such a problem.

  An object of the present invention is to achieve both reduction in the number of parts and improvement in supply reliability in a fuel cell system that supplies fuel gas from a plurality of high-pressure tanks.

  An object of the present invention is to develop a new technique for detecting an open / closed state of a valve when the open / close valves for each high-pressure tank are simultaneously opened.

  In one aspect of the fuel cell system of the present invention, a plurality of high-pressure tanks that store fuel gas at high pressure, an on-off valve that is provided for each high-pressure tank and switches on / off of gas supply from the high-pressure tank, and each high-pressure tank A gas supply path that joins and leads the fuel gas supplied from the tank; a fuel cell that receives supply of the fuel gas through the gas supply path; A pressure sensor that detects the pressure indicated by the combined fuel gas, a measuring means that measures the amount of power generated by the fuel cell, a temporal change in pressure detected by the pressure sensor, and an amount of power that is measured by the measuring means Determination means for making a determination related to the opening / closing of the on-off valve based on the correspondence relationship.

  The fuel gas is a gas consumed by the fuel cell. Typically, hydrogen gas is used as the fuel gas. The high-pressure tank is a pressure vessel that stores fuel gas at a high pressure. High pressure refers to a pressure higher than 1 atmosphere (0.1 MPa). The high-pressure tank normally stores fuel gas at a pressure of about several tens of MPa when the tank is full. For each high-pressure tank, at least one openable / closable valve is provided on the high-pressure tank itself or on the gas supply path. When the on-off valve is opened, the fuel gas in the high-pressure tank is released and gas is supplied. When the on-off valve is closed, the fuel gas from the high-pressure tank is maintained without being released, and the gas is supplied. Is not done. The opening and closing of the on-off valve is typically performed automatically based on a control signal, but may be performed manually. Note that the degree of opening of the on-off valve may be adjustable in multiple stages.

  The gas supply path is a flow path for supplying fuel gas to the inside of the fuel cell and is usually constructed using a pipe. The gas supply path joins the fuel gas from all the high-pressure tanks and supplies it to the fuel cell. For this reason, the gas supply path is provided with, for example, a branch flow path for collecting fuel gas from each high-pressure tank and a combined flow path that joins the branch flow paths. However, it is also possible to adopt a configuration in which each high-pressure tank is directly connected to one flow path. A fuel cell is a device that generates power by a chemical reaction that oxidizes fuel gas. In the fuel cell, electric energy of electric power corresponding to the supply amount of fuel gas (in other words, consumption amount of fuel gas) is generated. Here, the electric energy is obtained by integrating electric power over time.

  The pressure sensor detects the pressure indicated by the joined fuel gas in the gas supply path. In general, since gas moves so as to eliminate pressure variations, it exhibits a relatively uniform pressure distribution in a limited space such as a gas supply path. Therefore, the pressure indicated by the joined fuel gas does not need to be detected downstream of the joining point, and may be detected upstream of the joining point (for example, the aforementioned branch flow path). However, when an on-off valve is provided in the branch flow path, the equipment can be simplified by performing measurement downstream of the on-off valve so that pressure can be detected regardless of whether the on-off valve is opened or closed.

  The measuring means measures directly or indirectly the amount of power generated by the fuel cell. Direct measurement refers to measuring the amount of generated power itself, for example, an aspect in which the output current at each time is measured and the amount of power is obtained based on this. On the other hand, the indirect measurement is a derivative amount generated as a result of power generation, which is to measure an amount determined according to the amount of power and to evaluate the amount of power based on this measurement result. For example, when there is a motor that generates rotational energy in accordance with the amount of generated electric power, a mode in which the amount of electric power is evaluated by measuring the rotation status (rotational speed, rotational speed, etc.) of the motor can be cited. The indirect measurement result may be converted into a unit of electric energy, but may not be converted. However, even if it is not converted, the determination means makes the determination by using the correspondence between the indirect measurement result and the power amount explicitly or implicitly. Can be considered as measured. Note that the measurement of the electric energy by the measuring unit is sufficient if it is performed with an accuracy that allows determination by the determining unit, and may be performed approximately.

  The determination means is constructed using a computer having a calculation function, and performs determination regarding opening / closing of the on-off valve. This determination is made based on the correspondence between the temporal change in pressure detected by the pressure sensor and the amount of power measured by the measuring means. In general, when fuel gas supplied from a high-pressure tank is supplied, the pressure of the fuel gas in the high-pressure tank and the gas supply path decreases. The temporal change in pressure depends on the number of high-pressure tanks that supply fuel gas. For example, as the number of high-pressure tanks that supply fuel gas increases, the temporal change in pressure decreases. Therefore, by comparing the temporal change in pressure with the amount of electric power generated during this time (which corresponds to the amount of gas supply), it is possible to determine whether the on-off valve is opened or closed.

  According to this configuration, it is possible to make a determination regarding the on-off valve using the amount of power generated by the fuel cell. In general, the amount of power can be measured relatively easily, and a measuring device is often provided in advance for use in another application such as control of the amount of power. Therefore, simplification of the equipment for determination regarding the on-off valve can be expected.

  In one aspect of the fuel cell system of the present invention, the determination regarding the opening / closing of the on-off valve performed by the determination means is performed by determining the number of open / close valves opened or determining the number of open / close valves closed. It is.

  In one aspect of the fuel cell system of the present invention, the on-off valve includes a switching mechanism that switches between an open state and a closed state based on a control signal, and the determination regarding the opening / closing of the on-off valve performed by the determination unit is based on the control signal This is a determination of whether or not there is a malfunction in switching between opening and closing of the on-off valve. An example of an on-off valve provided with a switching mechanism that switches between an open state and a closed state based on a control signal may be a solenoid valve. The presence or absence of malfunction can be determined based on the number of open / close valves opened or the number of open / close valves closed. The determination may be made without specifying the number or the number of open / close valves in the closed state.

  In one aspect of the fuel cell system of the present invention, a control signal for normalizing the open / close state is transmitted to the on / off valve when it is determined that there is an on / off valve that has malfunctioned as a result of the determination by the determining means. A transmission means is provided. By automatically normalizing the open / close state of the tank in this way, for example, it is possible to reduce variations in use between the high-pressure tanks.

  In one aspect of the fuel cell system of the present invention, the transmission means transmits the same kind of control signal to all the on-off valves to be controlled. In this method, it is possible to reduce the number of parts related to transmission control.

  In one aspect of the fuel cell system of the present invention, the transmission unit transmits a control signal individually to each on-off valve, and the fuel cell system further includes a control signal transmission result by the transmission unit. Recording means for specifying and recording the malfunctioning on-off valve. Note that the transmission result refers to information obtained by transmission, and can be exemplified, for example, that the situation has changed due to transmission or that the situation has not changed. As a specific mode, there is an example in which, when a control signal for opening is transmitted, and when an increase in pressure is detected through the pressure sensor, it is detected that the opening / closing valve has changed from a closed state to an open state. . The recorded information can be used for maintenance and inspection.

  This embodiment is illustrated below.

  FIG. 1 is a diagram illustrating an outline of a configuration example of a fuel cell vehicle 10 according to the present embodiment. The fuel cell vehicle 10 includes a vehicle body 12 and wheels 14 that support the vehicle body 12 so as to be able to travel. The vehicle body 12 is equipped with a fuel cell system 15 and a motor 48 that is rotated by electric power supplied from the fuel cell system 15. The motor 48 drives the wheels 14, thereby causing the fuel cell vehicle 10 to travel.

  The fuel cell system 15 is provided with four high-pressure tanks 16, 18, 20, and 22 that store hydrogen gas as fuel gas. Main stop valves 24, 26, 28, and 30 are provided in the vicinity of the caps of the high-pressure tanks 16, 18, 20, and 22, respectively. The main stop valves 24, 26, 28, 30 are constituted by electromagnetic valves that open and close based on a control signal. Branch passages 32, 34, 36, and 38 are provided at the ends of the main stop valves 24, 26, 28, and 30, respectively, and hydrogen gas supplied from the high-pressure tanks 16, 18, 20, and 22 flows. It is. The branch channels 32, 34, 36, and 38 are integrated into a single combined channel 40 on the downstream side.

  The joint channel 40 is provided with a pressure reducing valve 42 to reduce the pressure of the hydrogen gas on the downstream side thereof. Further, the combined flow path 40 is provided with a pressure gauge 44 on the upstream side of the pressure reducing valve 42, and detects the pressure of hydrogen gas before pressure reduction in the combined flow path 40. When the main stop valves 24, 26, 28, 30 are opened on the downstream side of the pressure reducing valve 42, the pressure is maintained at the same pressure as the high pressure tanks 16, 18, 20, 22. Will detect this pressure.

  A fuel cell 46 is disposed downstream of the combined flow path 40. The fuel cell 46 is a device that generates electric power using hydrogen gas supplied through the joint channel 40 as fuel. Power generation is performed by causing a chemical reaction that oxidizes hydrogen gas and extracting the power. For this reason, the amount of electric power generated is in accordance with the consumption (supply amount) of hydrogen gas. The generated electric power is supplied to the motor 48.

  The fuel cell system 15 is also provided with an electric control unit 50. The electric control unit 50 is a device provided with computer hardware, and by a program (software), an electric energy measurement unit 52, a determination unit 54, a determination condition storage unit 56, a transmission unit 58, a correction confirmation unit 60, and a recording Part 62 is constructed.

  The electric energy measuring unit 52 periodically measures the output current of the fuel cell 46, and based on the measurement result, a set time (this time is set to an extent that can be determined by the determining unit 54). The amount of power generated within is calculated. The determination unit 54 inputs the electric energy calculated by the electric energy measurement unit 52 and the pressure detected by the pressure gauge 44, and based on the determination conditions stored in the determination condition storage unit 56, the main stop valves 24, 26, The presence or absence of malfunctions at 28 and 30 is detected. The determination condition can be implemented, for example, as a lookup table or as an arithmetic expression. Specifically, the determination unit 54 detects whether or not there are main stop valves 24, 26, 28, and 30 that are not open even though they should be open. When it is determined that there is a malfunction, the transmission unit 58 transmits an inrush current as a control signal for opening the valves to all the main stop valves 24, 26, 28, and 30. The inrush current is an electric current for applying an electromagnetic action to the main stop valves 24, 26, 28, and 30 which are electromagnetic valves to open the valves.

  The correction confirmation unit 60 detects that the pressure detected by the pressure gauge 44 has increased as a result of transmitting the inrush current, thereby confirming that the malfunction of the valve has been corrected. On the other hand, if it cannot be confirmed, the inrush current may be transmitted to the transmission unit 58 again. The re-transmission of the inrush current can be repeated a predetermined number of times. The recording unit 62 records the confirmation result by the correction confirmation unit 60. The transmitting unit 58 can also transmit the inrush current to each main stop valve 24, 26, 28, 30 individually. In this case, the correction confirmation unit 60 can specify the main stop valve that has malfunctioned, and the recording unit 62 performs recording that specifies the main stop valve.

  Next, the flow of control by the electric control unit 50 will be described using the flowchart of FIG.

  When the operation of the fuel cell vehicle 10 is started, the transmission unit 58 transmits an inrush current that causes the main stop valves 24, 26, 28, and 30 to open the valves (S10). As a result, the hydrogen gas stored in the high-pressure tanks 16, 18, 20, and 22 is supplied to the fuel cell 46 through the branch passages 32, 34, 36, and 38 and the combined passage 40.

  The pressure in the joint channel 40 detected by the pressure gauge 44 is periodically input to the electric control unit 50 (S12), and the current output from the fuel cell 46 is also periodically input to the electric control unit 50 (S14). . When the set predetermined time has elapsed (S16), the determination unit 54 calculates how much pressure change has occurred during this time (S18). Further, the power amount measuring unit 52 calculates how much power is generated at this time, and outputs it to the determination unit 54 (S20).

  Based on the determination conditions stored in the determination condition storage unit 56, the determination unit 54 determines whether or not “absolute value of pressure change> electric energy × conversion constant + α” is satisfied. Here, the conversion constant is a proportional constant for adjusting the unit of electric energy to the unit of pressure change, and is determined by the performance of the fuel cell 46, the capacity of the high-pressure tanks 16, 18, 20, 22 and the like. In addition, “α” is set in consideration of measurement error and the like. As a result, if no, that is, if the pressure change is smaller, it is considered that all the main stop valves 24, 26, 28, 30 are normally opened, and the process returns to step S12 again. On the other hand, if yes, that is, if the pressure change is larger, it is determined that the main stop valves 24, 26, 28, and 30 have malfunctioned (S24), and the transmission unit 58 has an inrush current that opens the valve. Is transmitted (S26).

  The correction confirmation unit 60 determines whether there has been a pressure change after the inrush current is transmitted. And when there is a pressure change, after making it record on the recording part 62, it returns to step S12. On the other hand, when there is no pressure change, the transmission of the inrush current is repeated until the set number of times is reached (S30). Note that if the answer is no in step S22, or if the answer is yes in steps S28 and S30, the process may be terminated.

  In the above, an example in which the amount of power output from the fuel cell 46 is directly measured and compared with a pressure change has been described. However, the amount of power output from the fuel cell 46 can be indirectly measured from, for example, the travel distance of the fuel cell vehicle 10 and the degree of opening of the accelerator.

1 is a schematic diagram showing a configuration example of a fuel cell vehicle 10 according to the present embodiment. 5 is a flowchart for explaining an example of control in an electric control unit 50.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Fuel cell vehicle, 12 Car body, 14 wheels, 15 Fuel cell system, 16, 18, 20, 22 High pressure tank, 24, 26, 28, 30 Main stop valve, 32, 34, 36, 38 Branch flow path, 40 Joint flow path , 42 Pressure reducing valve, 44 Pressure gauge, 46 Fuel cell, 48 Motor, 50 Electric control unit, 52 Electric energy measurement unit, 54 Judgment unit, 56 Judgment condition storage unit, 58 Transmission unit, 60 Correction confirmation unit, 62 Recording unit.

Claims (6)

A plurality of high pressure tanks for storing fuel gas at high pressure;
An on-off valve that is provided for each high-pressure tank, and switches the presence or absence of gas supply from the high-pressure tank by opening and closing;
A gas supply path that guides the fuel gas supplied from each high-pressure tank by merging,
A fuel cell that receives a supply of fuel gas through a gas supply path and generates electric power according to the supply amount; and
A pressure sensor provided in the gas supply path for detecting the pressure indicated by the joined fuel gas;
Measuring means for measuring the amount of power generated by the fuel cell;
Determination means for making a determination on opening / closing of the on-off valve based on a correspondence relationship between the temporal change in pressure detected by the pressure sensor and the amount of electric power measured by the measurement means;
A fuel cell system comprising: The fuel cell system according to claim 1, wherein
The determination relating to the opening / closing of the on-off valve performed by the determining means is a determination of the number of open / close valves opened or a determination of the number of open / close valves closed. The fuel cell system according to claim 1, wherein
The on-off valve includes a switching mechanism that switches between an open state and a closed state based on a control signal,
The determination regarding the opening / closing of the on-off valve performed by the determining means is a determination of whether or not there is a malfunction in switching of the on-off valve opening / closing by a control signal. The fuel cell system according to claim 3, further comprising:
A fuel cell system comprising: transmission means for transmitting a control signal for normalizing the open / close state to the open / close valve when it is determined by the determination means that there is a malfunctioning open / close valve. The fuel cell system according to claim 4, wherein
The fuel cell system characterized in that the transmitting means transmits the same kind of control signal to all the on-off valves to be controlled. The fuel cell system according to claim 4, wherein
The transmission means transmits a control signal individually to each on-off valve,
The fuel cell system further comprises recording means for identifying and recording a malfunctioning on-off valve based on the transmission result of the control signal from the transmission means.

Images