KR102563575B1 - Regulator fault diagnosis method for high pressure gas tank - Google Patents

Abstract

The present invention is a high-pressure container capable of accommodating gas therein; a regulator front end line extending from the high-pressure vessel and connected to a front end of the regulator; and a downstream line extending from the regulator and provided to supply the gas to the stack, wherein when the gas is supplied from the high-pressure vessel to the stack, the density of the front line and the downstream line, The present invention relates to a method for diagnosing a failure of a regulator for determining whether a failure occurs in the regulator.

Description

Regulator fault diagnosis method for high pressure gas tank

The present invention relates to a failure diagnosis method capable of determining whether a failure has occurred in a regulator fastened to a high-pressure container and reducing a high-pressure gas supplied from the high-pressure container, and in detail, the temperature at the front of the regulator and the pressure at the rear of the regulator. A method for diagnosing whether or not a failure of a regulator has occurred based on a density value calculated by the value.

In general, a fuel cell system includes a fuel cell stack that generates electrical energy, a fuel supply system that supplies fuel (hydrogen) to the fuel cell stack, and an air supply that supplies oxygen in the air, which is an oxidant required for an electrochemical reaction, to the fuel cell stack. system, and a heat and water management system that controls the operating temperature of the fuel cell stack.

High-pressure compressed hydrogen of about 700 bar is stored in the hydrogen tank provided in the fuel supply system, that is, the hydrogen supply system, and the stored compressed hydrogen is turned on / off by a high-pressure regulator installed at the inlet of the hydrogen tank. After being discharged to the high-pressure line according to the pressure, it is reduced in pressure through the start valve and the hydrogen supply valve and supplied to the fuel cell stack.

At this time, high-pressure gas is used as fuel (hydrogen), so a gas storage container is required to store and discharge the gas as needed. In particular, since gas has a low storage density in a container, it is efficient to store it at high pressure, but it has the disadvantage of being exposed to the risk of explosion due to high pressure. In particular, since alternative fuel gas vehicles have a limited mounting space for the storage container, securing safety while maintaining the storage pressure at a high pressure is the core of the technology.

Therefore, in the case of a composite container among these fuel gas storage containers, the outer shell must be reinforced with a fiber-reinforced composite material having high specific strength and specific stiffness in order to withstand the high internal pressure of hydrogen gas, and a liner to maintain gas tightness is inserted inside. . In detail, two hemispherical liners are joined at both ends to form one storage container.

When a vehicle equipped with such a fuel gas storage container is driven, when fuel gas is supplied from the fuel gas storage container to the stack according to the law of thermodynamics, an adiabatic expansion phenomenon occurs inside the fuel gas storage container, that is, the high-pressure container, and the stored gas temperature can go down. In other words, when a vehicle equipped with a fuel gas storage container runs and consumes fuel gas, the fuel gas storage container can be cooled.

Republic of Korea Patent No. 10-1134647 (2012. 04. 02) Republic of Korea Patent No. 10-1646382 (2016. 08. 01)

According to a conventional method for determining the failure of a regulator by pressure at the front and/or rear of the regulator, the pressure change at the front and/or rear of the regulator according to the temperature change at the front and/or the rear of the regulator, and the pressure caused by the leak. Since the changes can occur simultaneously, the accuracy of diagnosing regulator failure has been compromised.

Therefore, in the present invention, the regulator failure is diagnosed by measuring the density of the regulator before and after the fuel gas is supplied from the high-pressure container according to the temperature and pressure values that can be measured at the front and/or the rear of the regulator. By doing so, it provides a fault diagnosis method that can accurately determine whether or not a regulator fault has occurred despite a rapid change in temperature.

As one embodiment of the present invention for achieving the above object, a high-pressure container capable of accommodating gas therein; a regulator front end line extending from the high-pressure vessel and connected to a front end of the regulator; and a regulator downstream line extending from the regulator and provided to supply the gas to the stack,

When the gas is supplied from the high-pressure container to the stack, a regulator failure diagnosis method is provided for determining whether a failure occurs in the regulator based on the densities of the front-end line and the downstream line.

In addition, a regulator failure diagnosis method in which the density is calculated by the temperature measured in the front line and the pressure measured in the rear line is provided.

In addition, a regulator failure diagnosis method for determining that the regulator has failed when the density is equal to or greater than a preset value is provided.

Through the above problem solving means, the present invention provides the following effects.

According to the present invention, since it is possible to accurately diagnose whether or not a failure of the regulator has occurred regardless of a rapid change in temperature, the safety of vehicle driving can be improved.

In addition, according to the present invention, even if the pressure value measured at the front and/or rear end of the regulator rapidly changes, it is possible to distinguish between a case where the regulator actually fails and a case where the pressure rapidly changes due to a change in temperature, so that the fuel cell system Overall stability can be increased.

1 is a diagram showing the configuration and connection relationship of a fuel cell system according to an embodiment of the present invention.
2 is a table showing temperature and pressure measured before and after the regulator is opened, at the front and rear ends of the normally operating regulator.
3 is a table showing density changes calculated by temperature and pressure before and after the regulator is opened, at the front and rear ends of the regulator according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. Embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be construed as being limited to the following examples. This embodiment is provided to more completely explain the present invention to those skilled in the art.

In addition, terms such as "...unit", "...unit", and "...module" described in the specification mean a unit that processes at least one function or operation, which is hardware, software, or hardware and It can be implemented as a combination of software.

A fuel cell system installed in a vehicle is largely composed of a fuel cell stack generating electrical energy, a fuel supply device supplying fuel (hydrogen) to the fuel cell stack, and supplying oxygen in the air, an oxidizing agent required for an electrochemical reaction, to the fuel cell stack. It consists of an air supply device, a cooling system that removes reaction heat from the fuel cell stack to the outside of the system and controls the operating temperature of the fuel cell stack.

In the fuel supply system of the fuel cell system, a high-pressure container loaded with fuel may exist as a fuel storage tank. In the high-pressure vessel, hydrogen is preferably loaded and used as fuel, and high-pressure hydrogen gas of about 700 bar can be stored inside the vessel.

Accordingly, a high-pressure state due to fuel or hydrogen may be maintained inside the high-pressure container, and the gas may pressurize the high-pressure container. In particular, if a leak or breakage occurs at one point of the high-pressure container, the internal high pressure is concentrated at one point, causing damage to the high-pressure container and subsequent explosion. It is a very important element in a vehicle that can be equipped with a battery system.

1 is a diagram showing the configuration and connection relationship of a fuel cell system according to an embodiment of the present invention. According to FIG. 1, in the present invention, a regulator for reducing the pressure of hydrogen supplied on a line extending from the high-pressure vessel to the stack may be provided. In addition, a gas flow line through which gas, preferably hydrogen, can move may be provided between the high-pressure container and the regulator and between the regulator and the fuel electrode of the stack.

Hereinafter, for convenience of explanation, the line between the high-pressure container and the regulator, that is, the hydrogen transfer line extending from the high-pressure container and provided to be connected to the front end of the regulator, is referred to as a 'regulator front end line 100', and from the regulator A line provided to extend and move gas (preferably hydrogen) to the stack may be referred to as a 'regulator downstream line 200'.

Furthermore, according to FIG. 1 , in one embodiment of the present invention, a check valve, a shut-off valve, a ventilation hole for inflow/output of outside air, and a thermally activated pressure relief device (TPRD) may be provided. In the case of the above configuration, since it is widely known to those skilled in the art in the field of fuel cell systems, a detailed description thereof may be omitted.

Meanwhile, referring again to FIG. 1 , the regulator may depressurize the high-pressure hydrogen supplied from the high-pressure container and then supply the high-pressure hydrogen to the stack, preferably to the fuel electrode of the stack. Specifically, when hydrogen stored at a pressure of about 700 bar inside the high-pressure vessel passes through the regulator, it can be reduced to a pressure of about 16 bar. However, when a failure occurs in the regulator, in particular, when a leak occurs in the regulator, the regulator may not be completely opened and closed. In this case, even when the regulator is closed, since the high-pressure hydrogen in the front end line 100 of the regulator leaks into the downstream line 200 of the regulator through a leak, the pressure in the downstream line 200 of the regulator may be formed to be abnormally high. .

According to one embodiment of the present invention, when the pressure of the downstream line 200 of the regulator is about 14.5 bar to about 18.5 bar, it can be determined that the regulator is operating normally. It can be judged that this has occurred.

If it is determined that a failure of the regulator has occurred, non-ideal high pressure may be applied to the entire hydrogen supply system of the fuel cell system. Since the amount of hydrogen supplied to the anode of the stack is excessively large, the safety of the entire fuel cell system cannot be guaranteed.

Accordingly, in one embodiment of the present invention, when it is determined that a failure of the regulator has occurred, the vehicle may enter a shutdown mode (S/D). Among the modes of the vehicle referred to in the present invention, the 'shutdown mode' is a concept distinct from the state in which the ignition of the vehicle is turned off (Off). Since the vehicle's shutdown mode is a state in which safety of the vehicle is not guaranteed, it may mean a mode in which the engine is not restarted by a driver's arbitrary operation.

Meanwhile, when a vehicle equipped with a fuel cell system is running, that is, when gas, preferably hydrogen, is supplied as fuel from the high-pressure container to the stack through a regulator, adiabatic expansion may occur inside the high-pressure container. there is. That is, since inside the high-pressure vessel, hydrogen inside the high-pressure vessel is only discharged out of the high-pressure vessel without newly injected gas, so a phenomenon of adiabatic expansion may occur, and the temperature inside the high-pressure vessel and the temperature of the high-pressure vessel may decrease according to the laws of thermodynamics. . Therefore, when the vehicle equipped with the fuel cell system is running, the high-pressure container can be cooled.

Furthermore, when a vehicle equipped with a fuel cell system finishes driving, that is, when the ignition is turned off in a stopped state, the temperature of the entire vehicle including the high-pressure container may become the same as the outside air temperature after a certain period of time has elapsed. That is, the temperature of the high-pressure container may also become the same as the outside air temperature, and the external temperature of the high-pressure container may also rise to about 40° C. or higher at a high temperature such as in midsummer.

Meanwhile, when the temperatures of the high-pressure vessel, the front-end line 100 of the regulator, the downstream line 200 of the regulator, and the regulator rise above a certain temperature, the temperature of the gas flowing through the line inside the fuel cell system increases due to a natural phenomenon. can do. Since it is obvious that the pressure rises when the temperature of the gas rises, the pressure measured at the rear end of the regulator in a high temperature state can be affected by the temperature of the gas at the rear end of the regulator in addition to the factors caused by the gas leaking from the regulator.

2 is a table showing temperature and pressure measured before and after the regulator is opened, at the front and rear ends of the normally operating regulator. In FIGS. 2 and 3 , start may mean a time before the regulator is opened, and end may mean a time after the regulator is opened and then closed.

As described above, when the temperature of the high-pressure container changes a lot, that is, when the vehicle is parked or stopped while driving in midsummer and exposed to high external temperatures, the pressure in the rear end line 200 of the regulator is It can be seen that abnormally high numbers can be displayed. (Regulator end pressure up to 23.7 bar)

That is, as in the prior art, if the pressure in the downstream line of the regulator is simply measured, and if the pressure in the downstream line exceeds a certain value, it is determined that a failure has occurred in the regulator, whether leakage or water leakage has actually occurred due to the failure of the regulator. It was impossible to accurately distinguish whether the temperature of the downstream line of the regulator increased and the pressure also increased.

Therefore, in the following, in the present invention, the density value is calculated by the temperature and pressure measured in the front line 100 and/or the rear line 200 of the regulator, and based on the calculated density value, it is possible to determine whether or not an abnormality in the regulator has occurred. I would like to explain how to diagnose possible regulator failures.

According to one embodiment of the present invention, the temperature in the front end line 100 of the regulator can be measured over a period from before the regulator is opened to when it is opened and then closed again. In addition, according to an embodiment of the present invention, the pressure in the downstream line 200 of the regulator can be measured over a period from before the regulator is opened to when it is opened and then closed again.

Furthermore, the density ρ1 may be measured using the temperature value measured in the front line 100 before opening the regulator and the pressure value measured in the rear line 200. After that, the density (ρ2) can be measured in the same way at the time point after the regulator is opened and closed, that is, using the temperature value measured in the front line 100 and the pressure value measured in the rear line 200. .

Preferably, the density can be calculated by the following formula.

(Equation 1)

In the case of the above equation, it relates to an equation of state for a real gas, and is an equation for calculating the density according to the behavior of a real gas.

On the other hand, FIG. 3 shows the temperature of the front line 100 and the pressure of the rear line 200 at the time before the opening of the regulator and at the time of closing again after the opening of the regulator while variously changing the start temperature and end temperature of the normally operating regulator. This table shows the results of experiments to measure density values according to

According to FIG. 3, it can be seen that when the regulator is normally operated, the start and end densities do not exceed about 1.9 kg/m 3 regardless of the start and end temperatures. That is, according to an embodiment of the present invention, it can be determined that the regulator is operating normally if both densities (start density and end density) of the regulator before opening and after opening and closing again do not exceed about 1.9 kg/m 3 . can

In the case of density, since it can be proportional to the number of gas molecules present in the space, eliminating the variables of temperature and pressure, and if the number of gas molecules is maintained purely, the regulator blocks the hydrogen molecules supplied from the high-pressure container well. that can be judged as In other words, when a leak occurs in the regulator, since hydrogen molecules will continuously move from the front end line 100 to the downstream line 200 due to the pressure difference, the change in the number of hydrogen molecules in the regulator downstream line 200 is determined through the density. By tracking or following, it is possible to determine whether the regulator has failed or leaked.

Therefore, in one embodiment of the present invention, the density can be calculated using the temperature measured in the front line 100 and the pressure value measured in the rear line 200, and the operation is performed before the opening of the regulator and after opening. After closing again, it is performed twice over the time point, and if the calculated density value is greater than the preset value, it can be determined that the regulator has a failure or leak.

Considering that there is no significant difference in temperature values between the front line 100 and the downstream line 200 from the regulator, but the pressure value shows a large difference, in one embodiment of the present invention, the temperature value is the regulator front line It is measured at 100, and the pressure value can be measured at the downstream line 200 of the regulator.

In a preferred embodiment of the present invention, when rounding to the fourth decimal place and a density exceeding 1.9 kg/m 3 is calculated, it can be determined that a leak has occurred in the regulator.

In summary, the core idea of the present invention is characterized in that the variable caused by temperature is removed by measuring the density in the conventional method of determining whether a regulator has failed or leaked based on pressure, which is a factor that can change by temperature. . In particular, by measuring the temperature at the front end line 100 of the regulator and measuring the pressure at the downstream line 200 of the regulator, after the regulator is opened and completely closed again, whether the density value is maintained within a certain range or exceeds a preset value It should be noted that there is a feature of the present invention in determining whether or not to do so. That is, in the present invention, after the regulator is opened and closed, it is possible to determine whether leakage occurs from the regulator by focusing on the number of gas, preferably hydrogen molecules that may exist in the regulator downstream line 200, as fuel. as the core of the invention.

In addition, although the embodiments of the present invention have been described and described, those skilled in the art can add, change, delete, or add components within the scope not departing from the spirit of the present invention described in the claims. It will be possible to implement the present invention by various modifications and changes by addition, etc., and this will also be said to be included within the scope of the present invention.

Furthermore, in describing the embodiments of the present invention, if it is determined that a detailed description of a known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description is omitted. In addition, the terms used above are terms defined in consideration of functions in the embodiment of the present invention, which may vary according to the intention or custom of a user or operator. Therefore, the definition should be made based on the contents throughout this specification. Therefore, the above detailed description of the invention is not intended to limit the present invention to the disclosed embodiments, and the appended claims should be construed to include other embodiments as well.

100: regulator shear line
200: regulator rear end line

Claims (3)

A high-pressure container capable of accommodating gas therein;
a regulator front end line extending from the high-pressure vessel and connected to a front end of the regulator; and
A downstream line extending from the regulator and provided to supply the gas to the stack;
When the gas is supplied from the high-pressure vessel to the stack, the density is calculated using the temperature measured in the front line before opening of the regulator and the pressure measured in the rear line, and after the regulator is opened. After closing again, the density is calculated using the temperature measured in the front line and the pressure measured in the rear line, and if one or more of the density values calculated at each point is equal to or greater than a preset value, the regulator is out of order. A method for diagnosing a regulator fault that is judged to be
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