JP2006164828A - Fuel cell system and method for specifying fuel leakage point - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect the leakage of fuel gas and specify a leakage point even if great leakage such as the breakage of a fuel supply system occurs during steady operation. <P>SOLUTION: Pressures are detected at a plurality of points of the fuel supply system 1 during the steady operation. The leakage point is specified between a pressure sensor P6 positioned in the uppermost stream of the fuel supply system 1 out of detection points in each of which a detected value is below first fail pressure (approximate atmosphere pressure), and a pressure sensor P5 positioned in the upstream of the pressure sensor P6 where the detected value is below second fail pressure (a regulation value of a regulator Reg 5). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system and a method for identifying a fuel leak point thereof, and in particular, even when a large leak such as a breakage of a fuel supply system occurs during steady operation, a fuel gas leak can be detected and a leak point can be identified. Regarding technology.

2. Description of the Related Art In recent years, development of fuel cell-equipped vehicles using a fuel cell that generates power by an electrochemical reaction between fuel gas and oxygen in the air as a power source has been performed. In a fuel cell system mounted on this type of vehicle, it is very important to accurately detect leakage of fuel gas, particularly during operation. In order to meet such a demand, Patent Document 1 discloses that when the electric load of the fuel cell is smaller than a threshold value, the output current of the fuel cell is cut off, and the pressure in the closed space of the fuel gas supply circulation system including the fuel cell at this time is disclosed. A technique for detecting a gas leak of fuel gas in the closed space based on a state is disclosed.
JP 2003-308866 A

  In this patent document 1, since a minute leak is detected, when the output current of the fuel cell is small, the power generation is stopped and the gas leak is detected. In other words, since power generation is stopped during vehicle braking or the like and gas leak detection is performed, it is difficult to detect leaks and identify leak locations when a large leak such as damage occurs in the fuel supply circulation system during steady operation.

  Therefore, the present invention provides a fuel cell system capable of detecting a leak of fuel gas and specifying a leak location even when a large leak such as a damage of a fuel supply system occurs during steady operation, and a leak location specifying method. With the goal.

  In the fuel supply system that regulates the fuel gas from the fuel supply source and supplies it to the fuel cell, for example, when a pipe break occurs, the break point is opened to the atmosphere, so the pressure located downstream from the break point The detection means indicates the atmospheric pressure (gauge pressure) even during steady operation. Here, even when a pressure regulating means such as a pressure regulating valve is provided downstream of the breakage point, at least the pressure detection means located between the breakage point and the pressure regulation means indicates atmospheric pressure.

  On the other hand, when the pressure detecting means is provided between the pressure detecting means and the rupture location among the pressure detection means located upstream from the rupture location, the pressure detection means performs the pressure adjustment during the steady operation. Although the pressure is lower than the value, it does not indicate atmospheric pressure.

  Therefore, for example, when the atmospheric pressure or a pressure close thereto is set as the first predetermined value, while the pressure adjustment value during steady operation or a pressure close thereto is set as the second predetermined value, the first predetermined value is set. The pressure detection means A located in the uppermost stream of the fuel supply system among the pressure detection means below the value, and the pressure detection means located upstream from the pressure detection means A, the output of which is a second predetermined value. There will be a leakage point between the pressure detection means B and the pressure.

  Therefore, the fuel cell system of the present invention includes a fuel supply system that regulates fuel gas from a fuel supply source and supplies the fuel gas to the fuel cell, a plurality of pressure detection means provided in the fuel supply system, and these pressure detection means Determining means for determining whether or not the output of the output is below the first and second predetermined values (where the first predetermined value is less than the second predetermined value) during steady operation, and below the first predetermined value Among the pressure detection means, the pressure detection means A located in the uppermost stream of the fuel supply system, and the pressure detection means located upstream of the pressure detection means A, the output of which falls below the second predetermined value The structure provided with the specific means which pinpoints between the pressure detection means B as a leak location was employ | adopted.

  In this configuration, when the output of the pressure detection means A indicates a substantially atmospheric pressure, the specifying means may specify a portion between the pressure detection means A and the pressure detection means B as a breakage point. .

  In addition, the method for identifying a fuel leak location in the fuel cell system according to the present invention detects pressure at a plurality of locations in the fuel supply system during steady operation, and the detected value falls below a first predetermined value. A detection location A located at the uppermost stream of the fuel supply system, and a detection location located upstream from the detection location A, where the detected value is a second predetermined value (however, the first predetermined value <the second A configuration is adopted in which the gap between the detection point B and the detection point B that falls below the predetermined value is specified as a leak point.

  In such a configuration, when the detection value at the detection location A indicates substantially atmospheric pressure, a portion between the detection location A and the detection location B may be specified as a fracture location.

  According to the present invention, even when a large leak such as damage to the fuel supply system occurs during steady operation, early detection of the fuel gas leak and early identification of the gas leak location can be performed without forming a closed space in the fuel supply system. It becomes possible.

<First Embodiment>
FIG. 1 shows a system configuration diagram of a fuel cell system according to the first embodiment. This fuel cell system can be applied to an in-vehicle power generation system of a fuel cell vehicle, and can also be applied to, for example, a stationary power generation system.

  As shown in the figure, this fuel cell system includes a system for supplying hydrogen gas as a fuel gas to the fuel cell stack 10, a system 2 for supplying air, and a system for cooling the fuel cell stack 10. A system (not shown) is provided.

  The fuel cell stack 10 includes a stack structure in which a plurality of cells including a separator having a flow path of hydrogen gas, air, and cooling water and a MEA (Membrane Electrode Assembly) sandwiched between a pair of separators are stacked. Yes.

  A fuel supply system 1 for supplying hydrogen gas to the fuel cell stack 10 includes a plurality of (four) hydrogen tanks (fuel supply sources) 11, a hydrogen tank 11 and a fuel arranged in order from the hydrogen gas supply source. Piping 1a communicating with the battery stack 10, main stop valves SV1 to 4, pressure sensors (pressure detection means) P1 to P4 for detecting the line pressure between the main stop valves SV1 to 4 and the pressure regulating valves Reg1 to 4, pressure regulating valves A pressure sensor (pressure detecting means) P5 for detecting a line pressure between Reg1 to Reg4 and pressure regulating valves Reg1 to 4 to pressure regulating valve Reg5, a pressure for detecting a line pressure between pressure regulating valve Reg5, pressure regulating valve Reg5 and pressure regulating valve Reg6 A sensor (pressure detecting means) P6, a pressure regulating valve Reg6, a pressure regulating valve Reg6, a pressure sensor (pressure detecting means) P7 for detecting a pipe pressure between the fuel cell stack 10, a control unit (determining means, specifying means) 20 and the like are provided. There.

  The hydrogen tank 11 is a high-pressure hydrogen tank. Instead of the high-pressure hydrogen tank, a hydrogen tank using a hydrogen storage alloy, a hydrogen supply mechanism using a reformed gas, a tank for supplying hydrogen from a liquid hydrogen tank, a liquefied gas fuel A storage tank or the like is applicable.

  The main stop valves SV1 to SV4 control whether or not hydrogen gas is supplied from each hydrogen tank 11. The pressure regulating valves Reg1 to 4 reduce the internal pressure of the tank to a predetermined high pressure (for example, 3 Mpa), the pressure regulating valve Reg5 reduces the hydrogen gas reduced to the high pressure to a medium pressure (for example, 1 Mpa), and the pressure regulating valve Reg6 The hydrogen gas reduced to the intermediate pressure is reduced to a low pressure (for example, 0.2 MPa).

  The system 2 for supplying air to the fuel cell stack 10 is not shown in FIG. 1, but is an air cleaner that purifies the outside air and takes it into the fuel cell system, and compresses and supplies the taken-in air according to the control of the control unit 20. A compressor that changes the amount of air and air pressure, a humidifier that adds air to the compressed air by exchanging air off-gas and moisture, and the cooling system of the fuel cell stack 10 includes a radiator, A fan and a cooling pump are provided.

  The control unit 20 is a known computer system such as an ECU, and outputs a control signal for determining the driving amount of various auxiliary devices such as a compressor, or pressure sensors P1 to P7 disposed at various locations in the fuel supply system 1. In addition to outputting control signals for controlling the opening and closing of the main stop valves SV1 to SV4 and the pressure regulating valves Reg1 to 6 based on the detection signals from the fuel supply system 1 during steady operation according to the procedure (FIG. 2) described later. Detecting hydrogen gas leaks and identifying the location of the leak.

  That is, the control unit 20 of the present embodiment is configured such that the outputs of the pressure sensors P1 to P7 are the first fail pressure (first predetermined value) P_fail1 and the second fail pressure (second predetermined value) P_fail2 (however, In addition to functioning as a determination means that determines whether or not the failure pressure P_fail1 <the second failure pressure P_fail2) is lower than the first failure pressure P_fail1), fuel is supplied from the pressure sensors P1 to P7 that are lower than the first failure pressure P_fail1. Pressure sensors P1 to P7 located at the uppermost stream of the system 1, and pressure sensors P1 to P1 to 7 located upstream from the pressure sensors P1 to P7 whose output is lower than the second fail pressure P_fail2 It also functions as a specifying means for specifying between 7 and 7 as a leak point.

  “During steady operation” means a state in which at least the closed section is not formed in the fuel supply system 1, and is a state in which hydrogen gas is continuously supplied to the fuel cell stack 10.

  Next, an example of a process for detecting leakage of hydrogen gas in the fuel supply system 1 and specifying a leakage location, which is executed during steady operation in the fuel cell system, will be described with reference to the flowchart of FIG. However, here, as shown in FIG. 1, a case will be described in which a pipe breakage occurs between the pressure regulating valve Reg5 and the pressure regulating valve Reg6. Note that the processing shown in FIG. 2 is executed at predetermined intervals or in response to occurrence of a predetermined event.

  First, in step S1, the line pressure P5 between the pressure regulating valves Reg1-4 and the pressure regulating valve Reg5, the line pressure P6 between the pressure regulating valve Reg5 and the pressure regulating valve Reg6, and the line between the pressure regulating valve Reg6 and the fuel cell stack 10 The pressure P7 is detected by pressure sensors P5, P6, and P7, respectively. In the subsequent step S3, hydrogen gas leakage detection in the fuel supply system 1 is performed based on the outputs of the pressure sensors P5 to 7, that is, the pipeline pressures P5 to P7.

  Specifically, it is determined whether or not each of the pipe pressures P5 to P7 is lower than the first fail pressure P_fail. The first fail pressure P_fail is appropriately set according to the scale of gas leakage to be detected and specified, in other words, the degree of breakage. In the present embodiment, since the detection of the gas leak due to the pipe breakage and the specification of the leak location are performed, the first fail pressure P_fail is set to, for example, a substantially gauge pressure (atmospheric pressure).

  In the present processing example, as shown in FIG. 1, the pipe is broken between the pressure regulating valve Reg5 and the pressure regulating valve Reg6, and further upstream of the pressure sensor P6. Since the broken portion is open to the atmosphere, at least the pressure sensor P6 located downstream from the broken portion and upstream from the pressure regulating valve Reg6 exhibits a substantially gauge pressure even during steady operation.

  On the other hand, since the pressure regulating valve Reg5 is interposed between the pressure sensor P5 and the rupture location on the upstream side of the rupture location, the influence of the pressure drop due to the piping rupture is small. Therefore, the pressure sensor P5 shows a pressure slightly lower than the pressure regulation value of the pressure regulation valve Reg5 during steady operation, but does not drop to near atmospheric pressure. That is, assuming that the pressure adjustment value during normal operation is the second fail pressure P_fail2, between the pressure regulating valve Reg5 and the pressure regulating valves Reg1 to 4, "first fail pressure P_fail1 <pipe pressure P5 <second fail pressure P_fail2". "Is in the state.

  In addition to the pressure regulating valve Reg5, the pressure regulating valves Reg1 to 4 are also interposed between the breakage points and the pressure sensors P1 to P4. Therefore, piping between the main stop valves SV1 to 4 and the pressure regulating valves Reg1 to Reg4. The effect of pressure drop due to breakage is even less. Therefore, between the main stop valves SV1-4 and the pressure regulating valves Reg1-4, the state of "second fail pressure P_fail2 <pipe pressure P1-4" is established.

  From the above, among the pressure sensors that have fallen below the first fail pressure P_fail, the pressure sensor located at the uppermost stream of the fuel supply system 1 is the pressure sensor P6. A pressure sensor located upstream of the pressure sensor P6 and whose output is below the second fail pressure P_fail2 is a pressure sensor P5. Based on this result, it is specified that hydrogen gas leaks between the pressure sensor P5 and the pressure sensor P6 (step S5).

  Thereafter, the control unit 20 shuts off the main stop valves SV1 to SV4 (step S7), and stops the supply of hydrogen gas to the fuel cell stack 10.

  As for the piping between the pressure regulating valves Reg1 to 4-regulating valve Reg5 and the piping between the pressure regulating valve Reg5 and the fuel cell stack 1, hydrogen gas leakage can be detected and the location of the leakage can be specified.

  As described above, according to the fuel cell system of this embodiment, even when a large leak such as a pipe breakage of the fuel supply system 1 occurs during steady operation, the fuel supply system 1 does not form a closed space. Early detection of gas leaks and early identification of gas leak locations are possible.

<Other embodiments>
The present invention is not limited to application to a fuel cell system provided with the same number of pressure regulating valves Reg1 to Regulating a plurality of hydrogen tanks 11 as in the above embodiment (FIG. 1). For example, as shown in FIG. 3, the present invention can also be applied to a fuel cell system provided with a single pressure regulating valve Reg1, Reg3 for a plurality (two in the figure) of hydrogen tanks 11. Further, the positional relationship between the main stop valves SV1 to SV4 and the pressure regulating valves Reg1 to Reg4 may be reversed.

  In the above embodiment, the pressure sensors P1 to P7 are connected between the main stop valve SV1 to the pressure regulating valve Reg1 to 4, the pressure regulating valve Reg1 to 4 to the pressure regulating valve Reg5, the pressure regulating valve Reg5 to the pressure regulating valve Reg6, and the pressure regulating valve Reg6. Although one pipe is provided between the fuel cell stacks 10, a plurality of pressure sensors may be provided on these pipes.

  For example, when a pressure sensor (hereinafter referred to as “pressure sensor P10” for convenience of explanation) is provided between the pressure sensor 6 of FIG. 1 and the breakage point, the pressure sensor P10 also indicates a gauge pressure. There are a plurality of pressure sensors P6 and P10 that are below the first fail pressure P_fail1. Among them, the pressure sensor located at the uppermost stream of the fuel supply system 1 is the pressure sensor P10. In such a case, since the leak location is specified between the pressure sensor P10 and the pressure sensor P5 of the fuel supply system 1, it is possible to narrow the leak location to a narrower range.

1 is a configuration diagram showing a configuration of a fuel cell system according to a first embodiment of the present invention. The flowchart which shows the process which identifies the leak detection of the hydrogen gas in a fuel supply system, and a leak location performed during the steady operation of the fuel cell system. The block diagram which shows the structure of the fuel cell system which concerns on other embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel supply system, 10 ... Fuel cell stack (fuel cell), 11 ... Hydrogen tank (fuel supply source), 20 ... Control part (determination means, identification means), P1-P7 ... Pressure sensor (pressure detection means), Reg1-6 ... Pressure regulating valve

Claims (4)

A fuel supply system that regulates fuel gas from a fuel supply source and supplies the fuel gas to the fuel cell;
A plurality of pressure detection means provided in the fuel supply system;
Determination means for determining whether or not the output of these pressure detection means is below the first and second predetermined values (however, the first predetermined value <the second predetermined value) during steady operation;
Among the pressure detection means below the first predetermined value, the pressure detection means A located in the uppermost stream of the fuel supply system, and the pressure detection means located upstream from the pressure detection means A, the output of which is A specifying means for specifying a leak point between the pressure detection means B and a pressure below the second predetermined value;
A fuel cell system comprising:   2. The fuel according to claim 1, wherein when the output of the pressure detection means A indicates a substantially atmospheric pressure, the specifying means specifies a portion between the pressure detection means A and the pressure detection means B as a breakage point. Battery system. During steady operation, the pressure is detected at multiple points in the fuel supply system.
Among the detection points where the detection value is lower than the first predetermined value, the detection point A is located in the uppermost stream of the fuel supply system, and the detection point is located upstream from the detection point A. The detection value there is A method for identifying a fuel leak location in a fuel cell system, wherein a leak location is specified between a detection location B that falls below a second predetermined value (where the first predetermined value is less than a second predetermined value).   The fuel leak in the fuel cell system according to claim 3, wherein when the detection value at the detection location A indicates substantially atmospheric pressure, a portion between the detection location A and the detection location B is specified as a fracture location. How to identify the location.

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