Apparatus for diagnosing valve failure of a fuel cell system

Abstract

An apparatus for diagnosing a valve failure of a fuel cell system can accurately and quickly determine whether an integrated valve in the fuel cell system is abnormally operated and prevent problems caused by the abnormal operation of the integrated valve.

Description

Technical Field

[0001] This disclosure relates to an apparatus for diagnosing valve failures in a fuel cell system. More specifically, the present invention relates to an apparatus for diagnosing valve failures in a fuel cell system, which can determine whether a valve in the fuel cell system has failed and prevent problems caused by valve failures. Background Technology

[0002] Typically, a fuel cell stack is a power generation device that converts the chemical energy of fuel into electrical energy by causing an electrochemical reaction between fuel gas and oxidant gas.

[0003] A fuel cell system installed on a vehicle along with a fuel cell stack includes, in addition to the fuel cell stack, a device for supplying reactant gases to the fuel cell stack.

[0004] Furthermore, the fuel cell system recycles unreacted hydrogen in the fuel cell stack, and when the impurity ratio of the recirculated hydrogen increases, the fuel cell system discharges the recirculated hydrogen into the exhaust pipe. Additionally, the fuel cell system stores water produced by the reaction of hydrogen and oxygen in the fuel cell stack in a water collector, and discharges the water into the exhaust pipe when the water level rises to a predetermined level. In this case, a water level sensor is used to detect the water level in the water collector.

[0005] In a fuel cell system, an integrated valve with drainage and hydrogen removal functions is used to open or close a channel to allow water and recirculated hydrogen, which are reactants in the fuel cell stack, to be discharged through that channel.

[0006] The water collector is designed so that when water and hydrogen coexist, water is discharged first, and hydrogen is discharged only after the water discharge is complete. A water level sensor determines whether water has been discharged from the water collector.

[0007] When the integrated valve is operating normally and thus hydrogen emission is complete, the increase in internal hydrogen concentration in the fuel cell stack can be estimated, or atmospheric pressure correction of the hydrogen pressure sensor can be performed.

[0008] Meanwhile, the water level sensor can only detect changes in the water level in the collector.

[0009] Therefore, when the integrated valve is operating in open mode, the controller can determine whether water is actually being discharged from the collector by the change in the signal value of the water level sensor.

[0010] Furthermore, when hydrogen purging is performed in a water collector where only hydrogen gas, which cannot be measured by the water level sensor, is present, the controller cannot determine whether the hydrogen gas has actually been removed.

[0011] Therefore, when the integrated valve fails to open due to foreign objects, freezing, or malfunction, or when the integrated valve is closed during hydrogen purging, it is impossible to know whether hydrogen purging was actually performed correctly and completed according to the purging command from the controller.

[0012] When estimating the hydrogen concentration in the fuel cell stack, the amount of hydrogen purging is calculated using the water-free information detected by the water level sensor and the holding time of the integrated valve opening command, and the level of increase in hydrogen concentration in the fuel cell stack is estimated. Therefore, even when hydrogen purging is not actually performed, it is determined that the hydrogen concentration in the fuel cell stack is increasing.

[0013] In this situation, since the fuel cell stack operates under the premise of an increased hydrogen concentration even if the hydrogen concentration in the fuel cell stack does not actually increase, the output or durability of the fuel cell stack may decrease due to a lack of hydrogen.

[0014] Furthermore, when performing atmospheric pressure calibration of the hydrogen pressure sensor, if the integrated valve is not actually operated, the calibration of the hydrogen pressure sensor does not obtain an appropriate value, causing the fuel cell stack to operate under hydrogen overpressure during normal operation, thus reducing hydrogen fuel efficiency. Summary of the Invention

[0015] This disclosure aims to address the aforementioned problems related to the prior art.

[0016] On the one hand, this disclosure provides an apparatus for diagnosing valve failures in a fuel cell system, which can accurately and quickly determine whether the integrated valve in the fuel cell system is malfunctioning, so as to prevent problems caused by malfunctions of the integrated valve.

[0017] The purpose of this disclosure is not limited to the foregoing objectives, and other objectives not mentioned herein may be understood from the following description and will also become apparent from the embodiments thereof. Furthermore, the objectives of this disclosure may be achieved by the means described in the appended claims and combinations thereof.

[0018] In an exemplary embodiment, this disclosure provides an apparatus for diagnosing valve failure in a fuel cell system. The apparatus includes: a water collector configured to store water and hydrogen discharged from a fuel cell stack; an integrated valve configured to open or close a passage through which the water and hydrogen stored in the water collector are discharged; and a controller configured to cause the integrated valve to enter a forced drive mode when the controller commands an opening or closing operation of the integrated valve, and to determine that the integrated valve is not operating properly based on information about the instantaneous rate of change of the drive current operating the integrated valve, and configured to determine that the integrated valve is faulty even after the integrated valve has entered the forced drive mode, when the integrated valve is not operating properly.

[0019] According to embodiments of this disclosure, when the water level in the collector is zero, the integrated valve is commanded to open, and when the integrated valve malfunctions, the controller may not perform hydrogen concentration estimation of the fuel cell stack, and may not perform zero-value correction of the hydrogen pressure sensor, which is configured to detect the hydrogen pressure supplied to the fuel cell stack.

[0020] In addition, when the water level in the collector is zero, the controller commands the opening of the integrated valve. When the integrated valve is operating normally, the controller can perform hydrogen concentration estimation of the fuel cell stack and zero value correction of the hydrogen pressure sensor after a set time.

[0021] In addition, when the water level in the collector is not zero, the controller commands the opening of the integrated valve. If the integrated valve operates normally and the water level in the collector does not drop, the controller can determine that the discharge channel of the integrated valve is blocked after a set time.

[0022] According to embodiments of this disclosure, when a command is given to close the integrated valve and the integrated valve does not operate normally, the controller may not perform hydrogen concentration estimation of the fuel cell stack. When a command is given to close the integrated valve and the integrated valve operates normally, the controller may perform hydrogen concentration estimation of the fuel cell stack after a set time has elapsed.

[0023] In addition, the controller can interrupt the hydrogen supply to the fuel cell stack when the integrated valve is commanded to close, and when a failure of the integrated valve is determined, and the pressure of hydrogen supplied to the fuel cell stack decreases.

[0024] Furthermore, when the integrated valve is commanded to close, and when a fault is determined in the integrated valve while the pressure of hydrogen supplied to the fuel cell stack does not decrease, the controller can limit the output of the fuel cell stack to less than or equal to a predetermined reference output.

[0025] According to an embodiment of this disclosure, when the integrated valve is commanded to open, and when the instantaneous rate of change of the drive current changes from a positive (+) value to a negative (-) value, and then changes from a negative (-) value to a positive (+) value again while the drive current of the integrated valve increases, the controller can determine that the opening operation of the integrated valve is normal.

[0026] Furthermore, when the integrated valve is commanded to close, and when the instantaneous rate of change of the drive current changes from a negative (-) value to a positive (+) value, and then changes from a positive (+) value to a negative (-) value again while the drive current of the integrated valve decreases, the controller can determine that the closing operation of the integrated valve is normal.

[0027] In addition, when the integrated valve enters the forced drive mode, the controller can command the integrated valve to operate according to the set opening duty cycle and the number of opening operations.

[0028] Other aspects and preferred embodiments of this disclosure will be discussed below.

[0029] It should be understood that the terms "vehicle" or "vehicular," or other similar terms as used herein, generally include motorized vehicles, such as passenger cars including sport utility vehicles (SUVs), buses, trucks, various commercial vehicles, water vehicles including various boats and vessels, aircraft, etc., and include hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles, and other alternative fuel vehicles (e.g., fuels derived from resources other than petroleum). As mentioned herein, a hybrid vehicle is a vehicle having two or more power sources, such as a gasoline-powered and an electric vehicle. As described herein, a hybrid vehicle is a vehicle having two or more power sources, such as a gasoline-powered vehicle and an electric vehicle. Attached Figure Description

[0030] The above and other features of this disclosure will now be described in detail with reference to certain exemplary embodiments of this disclosure shown in the accompanying drawings, which are given hereinafter by way of example only and are not intended to limit this disclosure, and wherein:

[0031] Figure 1 This is a diagram illustrating the configuration of a fuel cell system according to this disclosure;

[0032] Figure 2 This is a graph illustrating an example of the drive current waveform of an integrated valve according to this disclosure;

[0033] Figure 3 A graph illustrating the duty cycle of the integrated valve according to this disclosure is shown.

[0034] Figure 4 This is a flowchart illustrating a method for diagnosing faults based on the opening command of an integrated valve according to this disclosure;

[0035] Figure 5 This is a flowchart illustrating a method for diagnosing faults based on an integrated valve shut-off command according to this disclosure; and

[0036] Figure 6 This is a flowchart illustrating the process of determining the operating state of an integrated valve according to this disclosure.

[0037] It should be understood that the accompanying drawings are not necessarily drawn to scale, but are merely slightly simplified schematic representations of various preferred features of the basic principles of this disclosure. Specific design features of this disclosure, such as particular dimensions, orientations, positions, and shapes, will be determined in part by the specific intended application and environment of use.

[0038] Several figures are drawn throughout the accompanying drawings, and reference numerals denote the same or equivalent parts of this disclosure. Detailed Implementation

[0039] Exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings, which are suitable for easy implementation by those skilled in the art. However, the present disclosure is not limited to the embodiments disclosed herein and may be implemented in other forms.

[0040] Furthermore, throughout the specification, when an element is referred to as a “comprising” component, it means that the component may also include other components, unless otherwise specified, and other components are not excluded.

[0041] According to this disclosure, it is possible to accurately and quickly determine whether an integrated valve is malfunctioning, and to respond immediately to any malfunctions, thereby preventing problems caused by malfunctions of the integrated valve.

[0042] In this disclosure, without the additional installation of a pressure sensor in the water collector, the operational characteristics of the integrated valve are used to determine whether the integrated valve is operating normally.

[0043] According to this disclosure, when the water level in the collector is zero (0%), and the integrated valve is opened to purge only the hydrogen stored in the collector to the exhaust pipe of the fuel cell system, hydrogen purging failure and excessive hydrogen purging due to integrated valve failure can be prevented.

[0044] Furthermore, according to this disclosure, when atmospheric pressure calibration is performed on the hydrogen pressure sensor installed in the hydrogen supply line of the fuel cell stack with the integrated valve open, the failure to obtain the calibration value of the hydrogen pressure sensor, which may occur due to integrated valve failure, can be prevented.

[0045] Figure 1 This is a diagram illustrating the configuration of a fuel cell system according to an embodiment of the present disclosure.

[0046] like Figure 1 As shown, the fuel cell system may include a fuel cell stack 10, a water collector 20, an integrated valve 30, a water level sensor 22, a hydrogen pressure sensor 12, and a controller 40.

[0047] This section describes the configuration of abnormal diagnosis and corresponding control of the integrated valve 30, but in addition to the above configuration, the fuel cell system may also include the configuration of a general fuel cell system.

[0048] For example, a fuel cell system may include a hydrogen supply device for supplying hydrogen to the fuel cell stack 10 and an air supply device for supplying air to the fuel cell stack 10.

[0049] The fuel cell stack 10 is a power generation device that converts the chemical energy of fuel into electrical energy through the electrochemical reaction between fuel gas and oxidant gas.

[0050] When hydrogen, which serves as a fuel gas, reacts chemically with oxygen in the air, which serves as an oxidant gas, to generate electricity, the fuel cell stack 10 produces water due to the reaction of hydrogen and oxygen.

[0051] Water produced in fuel cell stack 10 falls due to gravity and is collected in water collector 20 located below fuel cell stack 10. When water produced in fuel cell stack 10 is discharged into water collector 20, some hydrogen gas from fuel cell stack 10 is also discharged into water collector 20 along with the water.

[0052] The water collector 20 stores water and hydrogen discharged from the fuel cell stack 10, and when the water level in the water collector 20 exceeds a predetermined level, the water collector 20 discharges water to the outside of the fuel cell system, and when the water discharge is complete, the water collector 20 can start discharging hydrogen.

[0053] For this purpose, the water level sensor 22 is configured to detect the height of the water stored in the water collector 20, and the integrated valve 30 is configured to open or close the passage of the water collector 20 to discharge water and hydrogen.

[0054] Unreacted hydrogen in the fuel cell stack 10 is collected in the water collector 20 and then recycled back to the fuel cell stack 10 for use. In other words, the hydrogen recycled back to the fuel cell stack 10 (i.e., the recirculated hydrogen) is recovered back to the fuel cell stack 10 through the water collector 20.

[0055] However, when the impurity ratio of the recirculated hydrogen is high, the hydrogen collected in the water collector 20 is not recirculated to the fuel cell stack 10, but is discharged to the outside of the fuel cell system along with the water.

[0056] The process of releasing the hydrogen collected in the collector 20 to the outside of the fuel cell system is called "hydrogen removal".

[0057] The integrated valve 30 is configured to open or close a passage for discharging water or hydrogen stored in the water collector 20 to the exhaust pipe of the fuel cell system. In other words, the integrated valve 30 is configured to open or close the passage of the water collector 20 connected to the exhaust pipe of the fuel cell system. In other words, the integrated valve 30 can be operated to open or close the passage through which water and hydrogen stored in the water collector 20 are discharged.

[0058] The integrated valve 30 can be a solenoid valve that operates when a drive current is applied. Specifically, the integrated valve 30 can be a valve in which the internal passage of the integrated valve 30 opens as the plunger moves to the open position when a drive current for opening or closing operation is applied to the coil.

[0059] The integrated valve 30 may include an inlet for introducing water and hydrogen and an outlet for discharging water and hydrogen, and an internal passage of the integrated valve 30 may be formed between the inlet and the outlet. Water and hydrogen stored in the water collector 20 can be discharged to the exhaust pipe of the fuel cell system through the internal passage of the integrated valve 30.

[0060] A hydrogen pressure sensor 12 is installed on the hydrogen supply line 14 of the fuel cell stack 10 and is configured to measure the pressure of the hydrogen supplied to the fuel cell stack 10.

[0061] The controller 40 is configured to control the opening and closing operations of the integrated valve 30. Specifically, the controller 40 determines whether operation of the integrated valve 30 is required, and operates the integrated valve 30 in either an open or closed mode as needed.

[0062] The controller 40 uses the signal from the water level sensor 22 to determine the water level of the water collector 20 and detect changes in the water level of the water collector 20.

[0063] The controller 40 can determine whether the discharge of water from the water collector 20 is complete by using the signal from the water level sensor 22. That is, the controller 40 determines whether water has actually been discharged from the water collector 20 based on the signal from the water level sensor 22.

[0064] When it is determined that the impurity ratio of the hydrogen recirculated from the water collector 20 to the fuel cell stack 10 is high, the controller 40 opens the integrated valve 30 to purge the hydrogen into the exhaust pipe of the fuel cell system.

[0065] The controller 40 can calculate the amount of hydrogen (i.e., hydrogen removal amount) that is purged into the exhaust pipe of the fuel cell system when the integrated valve 30 is open, based on the time during which the command to keep the integrated valve 30 open is completed from the time the water is discharged from the collector 20.

[0066] When it is determined that the integrated valve 30 is operating normally to open and thus the hydrogen purging of the collector 20 is complete, the controller 40 can estimate that hydrogen with a high impurity ratio is discharged from the fuel cell stack 10, thereby increasing the internal hydrogen concentration of the fuel cell stack 10 before the hydrogen purging of the collector 20 is performed.

[0067] When hydrogen is recovered from the water collector 20 and fed into the fuel cell stack 10, the controller 40 can estimate the internal hydrogen concentration of the fuel cell stack 10 based on the amount of hydrogen supplied to the fuel cell stack 10 from the hydrogen supply device (not shown) and the amount of recirculated hydrogen supplied to the fuel cell stack 10 from the water collector 20. Furthermore, when hydrogen is purged from the water collector 20 and discharged into the exhaust pipe of the fuel cell system, the controller 40 can estimate the hydrogen concentration of the fuel cell stack 10 based on the amount of hydrogen supplied to the fuel cell stack 10 from the hydrogen supply device and the amount of hydrogen purged from the water collector 20.

[0068] In addition, when the hydrogen purging of the water collector 20 is complete, the integrated valve 30 opens to communicate with the atmosphere, allowing the controller 40 to perform zero-value calibration on the hydrogen pressure sensor 12 installed in the hydrogen supply line 14.

[0069] In the event of an interruption in the supply of hydrogen to the fuel cell stack 10, the controller 40 can periodically open the integrated valve 30 to expose the hydrogen pressure sensor 12 to the atmosphere, thereby correcting the zero value of the hydrogen pressure sensor 12. Zero correction of the hydrogen pressure sensor 12 can be performed by opening the integrated valve 30, thus connecting the hydrogen pressure sensor 12 to the atmosphere.

[0070] When the integrated valve 30 is opened for hydrogen purging of the water collector 20, the hydrogen pressure sensor 12 is connected to the atmosphere to detect atmospheric pressure. Therefore, when the hydrogen purging of the water collector 20 is completed, the controller 40 obtains the calibration value of the hydrogen pressure sensor 12 (i.e., atmospheric pressure).

[0071] In other words, when the integrated valve 30 is operating normally to open, the controller 40 sets the pressure value (i.e., atmospheric pressure) measured by the hydrogen pressure sensor 12 to the zero value of the hydrogen pressure sensor 12.

[0072] Furthermore, when the controller 40 commands the integrated valve 30 to operate, the controller 40 can determine whether the opening and closing operations of the integrated valve 30 are performed normally based on information about the drive current of the opening operation of the integrated valve 30.

[0073] When a drive current is supplied, the integrated valve 30 performs an opening operation, and when the drive current supply is interrupted, the integrated valve 30 performs a closing operation.

[0074] like Figure 2 As shown, when the controller 40 indicates an opening command to the integrated valve 30, the drive current applied to the integrated valve 30 increases over time, and when the opening operation of the integrated valve 30 is completed, a notch-shaped current waveform is generated.

[0075] In addition, such as Figure 2As shown, when the controller 40 indicates a closing command to the integrated valve 30, the drive current applied to the integrated valve 30 decreases over time, and a block current waveform is generated when the closing operation of the integrated valve 30 is completed.

[0076] The controller 40 can calculate the instantaneous rate of change (slope) of the drive current over time to detect changes in the waveform of the drive current. In this case, the instantaneous rate of change of the drive current can be obtained by calculating the derivative of the function representing the change of the drive current over time.

[0077] When the drive current increases in response to the opening operation of the integrated valve 30, and when the instantaneous rate of change of the drive current changes from a positive (+) value to a negative (-) value, and then changes from a negative (-) value to a positive (+) value again, the controller 40 determines that the opening operation of the integrated valve 30 is normal and then completes the operation.

[0078] Furthermore, when the drive current decreases for the closing operation of the integrated valve 30, and when the instantaneous rate of change of the drive current changes from a negative value to a positive value and then from a positive value to a negative value again, the controller 40 determines that the closing operation of the integrated valve 30 is normal and then completes the operation.

[0079] As described above, when the controller 40 commands the integrated valve 30 to perform an opening or closing operation, the controller 40 can determine whether the integrated valve 30 is operating normally based on information about the instantaneous rate of change of the drive current.

[0080] Furthermore, when the controller 40 determines that the operation of the integrated valve 30 has not been performed based on information about the instantaneous rate of change of the drive current, that is, when diagnosing a fault in the integrated valve 30 based on information about the instantaneous rate of change of the drive current, in order to more accurately determine whether a fault has occurred in the integrated valve 30, the controller 40 puts the integrated valve 30 into a forced drive mode.

[0081] When the integrated valve 30 enters the forced drive mode, the controller 40 sends an operation command to the integrated valve 30 based on the set opening duty cycle and the number of opening operations. The opening duty cycle can be the opening operation time of the integrated valve 30. The integrated valve 30 is forced to repeat the opening and closing operations according to the number of opening operations.

[0082] In other words, in order to re-determine whether the integrated valve 30 has malfunctioned, the controller 40 puts the integrated valve 30 into a forced drive mode, in which the opening duty cycle and the number of opening operations of the integrated valve 30 are set.

[0083] When the integrated valve 30 enters the forced drive mode, the integrated valve 30 receives the operation command from the controller 40 according to the set opening duty cycle and the number of opening operations, regardless of the real-time water level and hydrogen quantity in the water collector 20.

[0084] For example, in forced drive mode, the opening duty cycle of integrated valve 30 can be set to 100%, and the number of opening operations of integrated valve 30 can be set to four.

[0085] The opening duty cycle of the integrated valve 30 can be a ratio to a predetermined reference operating time. For example, when the reference operating time of the integrated valve 30 is one second and the opening duty cycle of the integrated valve 30 is 100%, the integrated valve 30 opens for one second during each operation.

[0086] Furthermore, when the forced drive mode is executed, the integrated valve 30 operates periodically the same number of times as the set number of opening operations.

[0087] When the forced drive mode is executed, the opening duty cycle of the integrated valve 30 can be increased and its opening operation interval can be reduced compared with the normal drive mode.

[0088] Here, the general drive mode is the operating control mode of the integrated valve 30 used to discharge water or hydrogen from the water collector 20. In the general drive mode, the opening duty cycle of the integrated valve 30 is controlled to be less than 100%, and the integrated valve 30 is opened when it is necessary to discharge water or hydrogen from the water collector 20.

[0089] As described above, when the controller 40 determines that the integrated valve 30 is malfunctioning based on information about the instantaneous rate of change of the drive current, the controller 40 causes the integrated valve 30 to enter a forced drive mode, and diagnoses the malfunction of the integrated valve 30 based on whether the integrated valve 30 is malfunctioning when it enters the forced drive mode.

[0090] When the controller 40 determines that the integrated valve 30, which has entered the forced drive mode, is malfunctioning, the controller 40 confirms that the integrated valve 30 has failed.

[0091] Furthermore, when the controller 40 commands the opening operation of the integrated valve 30 and determines that the opening operation of the integrated valve 30 has not been performed based on information about the instantaneous rate of change of the drive current, the controller 40 immediately cancels the estimation of the internal hydrogen concentration of the fuel cell stack 10 so as not to perform the estimation.

[0092] When the integrated valve 30 operates normally to open according to the command, the hydrogen discharge of the water collector 20 is completed, and the opening operation of the integrated valve 30 terminates, that is, when the operating mode of the integrated valve 30 normally switches from the open mode to the closed mode, the controller 40 performs the hydrogen concentration estimation operation scheduled at the end time of the opening operation of the integrated valve 30.

[0093] The controller 40 may include a hydrogen concentration estimation unit for estimating the internal hydrogen concentration of the fuel cell stack 10. The hydrogen concentration estimation unit does not operate when the hydrogen concentration estimation operation is cancelled.

[0094] Furthermore, when the controller 40 commands the opening operation of the integrated valve 30, and determines that the opening operation of the integrated valve 30 has not been performed based on information about the instantaneous rate of change of the drive current, the controller 40 cancels the acquisition of the calibration value of the hydrogen pressure sensor 12 scheduled at the end time of the opening operation of the integrated valve 30, so as not to perform the acquisition.

[0095] When the integrated valve 30 operates normally to open and the hydrogen pressure sensor 12 is exposed to atmospheric pressure due to the opening operation of the integrated valve 30, the controller 40 sets the signal value obtained from the hydrogen pressure sensor 12 to the zero value of the hydrogen pressure sensor 12.

[0096] When the water level in the collector 20 is zero (0%) and the integrated valve 30 is operating normally to open, the controller 40 can determine that the hydrogen discharge from the collector 20 is being performed normally.

[0097] Therefore, when the water level in the collector 20 is zero (0%) and the integrated valve 30 operates normally to open according to the command, after a set time, the controller 40 performs the acquisition of the calibration value of the hydrogen pressure sensor 12 and performs the estimation of the internal hydrogen concentration in the fuel cell stack 10.

[0098] When the water level in the collector 20 is zero (0%) and the controller 40 diagnoses an operational abnormality in the integrated valve 30, the controller 40 cancels the zero-value calibration of the hydrogen pressure sensor 12, thereby preventing the failure of the zero-value calibration of the hydrogen pressure sensor 12 and the resulting reduction in hydrogen fuel efficiency.

[0099] In addition, when the water level in the collector 20 is zero (0%) and the controller 40 diagnoses an operational abnormality of the integrated valve 30, the controller 40 cancels the hydrogen concentration estimation of the fuel cell stack 10 to prevent errors in hydrogen concentration estimation.

[0100] When an error occurs in estimating the internal hydrogen concentration of the fuel cell stack 10, the hydrogen fuel efficiency may decrease because the internal hydrogen pressure of the fuel cell stack 10 is in an overpressure state during normal operation.

[0101] When the water level in the collector 20 is not zero, the controller 40 determines that the integrated valve 30 is operating in the open mode. However, even after a set time has elapsed, if the water level in the collector 20 does not actually decrease, the controller 40 determines that a malfunction has occurred due to a blockage in the discharge passage of the integrated valve 30.

[0102] In other words, the controller 40 determines that the integrated valve 30 operates in the open mode based on the command. However, if the water level in the collector 20 is not zero and does not decrease, the controller 40 determines that a malfunction has occurred due to blockage of the discharge passage of the integrated valve 30. When the discharge passage of the integrated valve 30 is blocked, water discharge from the collector 20 is not performed even when the integrated valve 30 is operated to open.

[0103] When the controller 40 commands the integrated valve 30 to close and determines that the closing operation of the integrated valve 30 is normal based on information about the instantaneous rate of change of the drive current, the controller 40 calculates the amount of hydrogen purging based on the time the opening command of the integrated valve 30 is held (i.e., the opening command holding time), and uses the amount of hydrogen purging to estimate the internal hydrogen concentration of the fuel cell stack 10.

[0104] Immediately before the controller 40 commands the integrated valve 30 to close, the controller 40 calculates the amount of hydrogen removed based on the time during which the integrated valve 30 is kept open from the point in time when the water in the water collector 20 is discharged.

[0105] Furthermore, when the controller 40 commands the integrated valve 30 to close and determines that the integrated valve 30 has not been closed based on information about the instantaneous rate of change of the drive current, the controller 40 cancels the estimation of the internal hydrogen concentration of the fuel cell stack 10 and puts the integrated valve 30 into a forced drive mode.

[0106] When the controller 40 commands the integrated valve 30 to close, and the integrated valve 30 does not operate in the closing mode even after it has entered the forced drive mode, the controller 40 determines that the integrated valve 30 has malfunctioned.

[0107] When controller 40 determines that integrated valve 30 has malfunctioned, controller 40 measures the pressure of hydrogen supplied to fuel cell stack 10 via hydrogen pressure sensor 12. Subsequently, when it is determined that the pressure of hydrogen supplied to fuel cell stack 10 has decreased over time, controller 40 interrupts the hydrogen supply to fuel cell stack 10. Interrupting the hydrogen supply to fuel cell stack 10 by controller 40 prevents excessive hydrogen leakage from hydrogen supply line 14 into the atmosphere and ensures the safety of vehicle occupants.

[0108] When the controller 40 confirms that the integrated valve 30 has malfunctioned and determines that the pressure of the hydrogen supplied to the fuel cell stack 10 has not decreased, the controller 40 limits the output of the fuel cell stack 10 to operate the fuel cell stack 10.

[0109] In the event of a confirmed malfunction in integrated valve 30, if it is determined that there is no pressure drop in the hydrogen supplied to fuel cell stack 10, controller 40 determines that there is no hydrogen leakage into the air, or that any hydrogen leakage into the air is negligible. Furthermore, because it is difficult to ensure the full performance of fuel cell stack 10 due to the lack of internal hydrogen concentration estimation, controller 40 controls the operation of fuel cell stack 10 while limiting its output. In this case, the output of fuel cell stack 10 can be limited to be less than or equal to a predetermined reference output.

[0110] In the following text, reference will be made to Figure 4 This describes a method for determining whether the integrated valve 30 has malfunctioned when the integrated valve 30 is commanded to open, and a response method for diagnosing a malfunction of the integrated valve 30.

[0111] Here, refer to Figure 4 The process of determining a fault in the integrated valve 30 and the process of responding to the fault are described in sequence, but this disclosure is not limited to the order of these processes.

[0112] Reference Figure 4 In S100, the controller 40 instructs the integrated valve 30 to open and determines the water level of the collector 20 based on the signal from the water level sensor 22. The water level of the collector 20 can be calculated based on the height from the inner bottom surface to the inner top surface of the collector 20 being within the range of 0% to 100%.

[0113] Next, in S110, it is determined whether the water level in the collector 20 is 0%. When the water level in the collector 20 is 0%, in S120, based on information about the instantaneous rate of change of the valve drive current, it is determined whether the integrated valve 30 is operated to open. The valve drive current is the drive current applied to the coil of the integrated valve 30 to operate the integrated valve 30.

[0114] When it is determined that the integrated valve 30 is operated to open, zero-value correction of the hydrogen pressure sensor 12 and estimation of the hydrogen concentration of the fuel cell stack 10 are performed in S130. With the integrated valve 30 open, the atmospheric pressure in the hydrogen pressure sensor 12, exposed to the atmosphere, is corrected to zero.

[0115] Furthermore, when it is determined based on information about the instantaneous rate of change that the integrated valve 30 is not operated to be open, that is, when it is determined that the opening operation of the integrated valve 30 has failed, the internal hydrogen concentration estimation of the fuel cell stack 10 and the zero value correction of the hydrogen pressure sensor 12 are immediately cancelled in S140, and the integrated valve 30 enters the forced drive mode in S150.

[0116] In S160, based on information about the instantaneous rate of change of the valve drive current, it is determined whether the integrated valve 30, which has entered the forced drive mode, is operated to open or close. If the opening and closing operation of the integrated valve 30 is not performed normally, a malfunction of the integrated valve 30 is confirmed in S170.

[0117] Furthermore, when the instantaneous rate of change of the valve drive current changes from a positive (+) value to a negative (-) value, and then changes from a negative (-) value to a positive (+) value again, it is determined that the integrated valve 30 has returned to the normal operating mode for normal operation.

[0118] Meanwhile, when it is determined in S110 that the water level of the water collector 20 is not 0%, it is determined in S180 whether the water level of the water collector 20 has dropped.

[0119] When the water level in the collector 20 drops, the process returns to S110, and the water level in the collector 20 is determined again.

[0120] When the water level in the collector 20 does not drop, information about the instantaneous rate of change of the valve drive current is obtained, and in S190, it is determined whether the integrated valve 30 is operated to open based on the information about the instantaneous rate of change of the valve drive current.

[0121] When it is determined that the integrated valve 30 is operating to open, the time during which the opening command of the integrated valve 30 is held (i.e., the opening command holding time) is measured, and in S200, the opening command holding time is compared with a predetermined reference time. When the opening command holding time exceeds the reference time, the integrated valve 30 is actually operated to open, but the water level in the collector 20 does not drop, thus confirming in S210 that a malfunction of the integrated valve 30 has occurred due to blockage of the discharge passage of the integrated valve 30.

[0122] When it is determined that the integrated valve 30 is not in the open state, the internal hydrogen concentration estimation of the fuel cell stack 10 and the zero value correction of the hydrogen pressure sensor 12 are immediately cancelled in S140, and the integrated valve 30 enters the forced drive mode in S150.

[0123] In S160, based on information about the instantaneous rate of change of the valve drive current, it is re-determined whether the integrated valve 30, which has entered the forced drive mode, has been operated to open or close. If it is determined, based on information about the instantaneous rate of change of the valve drive current, that the integrated valve 30 has not been opened or closed, a malfunction of the integrated valve 30 is confirmed in S170.

[0124] Furthermore, when the instantaneous rate of change of the valve drive current changes from a positive (+) value to a negative (-) value, and then changes from a negative (-) value to a positive (+) value again, it is determined that the integrated valve 30 has returned to the normal operating mode for normal operation.

[0125] As described above, by re-determining whether the operation of the integrated valve 30 has failed through the forced drive mode, the reliability of fault diagnosis of the integrated valve 30 can be improved.

[0126] When an operational malfunction occurs due to a temporary jamming of the integrated valve 30, electromagnetic force is induced in the valve coil, thus applying external force to the integrated valve 30 and resolving the temporary jamming. Specifically, when the integrated valve 30 jams due to moisture freezing, the temperature of the coil rises due to the current applied to the coil (i.e., the valve drive current), thereby heating the area around the coil and resolving the problem of the integrated valve 30 jamming due to moisture freezing.

[0127] In the following text, reference will be made to Figure 5 This describes a method for determining whether the integrated valve 30 has malfunctioned when the integrated valve 30 is commanded to close, and a response method during the fault diagnosis of the integrated valve 30.

[0128] Here, refer to Figure 5 The process of determining a fault in the integrated valve 30 and the process of responding to the fault are described in sequence, but this disclosure is not limited to the order of these processes.

[0129] Reference Figure 5 When the controller 40 indicates a closing command to the integrated valve 30 in S300, it acquires information about the instantaneous rate of change of the valve drive current, and in S310 determines whether the integrated valve 30 is operated to close based on the information about the instantaneous rate of change of the valve drive current.

[0130] As a result determined in S310, when it is determined that the integrated valve 30 is actually operated to be closed, the amount of hydrogen discharged from the water collector 20 (i.e., the hydrogen removal amount) is calculated in S320, and the internal hydrogen concentration of the fuel cell stack 10 is estimated in S330. The hydrogen removal amount can be calculated based on the duration for which the opening command of the integrated valve 30 is held.

[0131] As a result of the determination in S310, when it is determined that the closing operation of the integrated valve 30 has failed, the hydrogen concentration estimation of the fuel cell stack 10 is immediately cancelled in S340, and the integrated valve 30 enters the forced drive mode in S350.

[0132] Subsequently, at S360, it is determined whether the integrated valve 30, which has entered the forced drive mode, is operated to open or close. The determination of whether the integrated valve 30 is operated to open or close is based on information about the instantaneous rate of change of the valve drive current.

[0133] When an opening or closing operation of the integrated valve 30 according to the forced drive mode is performed, an opening command is indicated to the integrated valve 30 (S370). Furthermore, when an opening or closing operation of the integrated valve 30 according to the forced drive mode is not performed, a final determination is made in S380 that the integrated valve 30 has malfunctioned.

[0134] When the integrated valve 30 fails to operate normally according to the forced drive mode, i.e., when a malfunction of the integrated valve 30 is confirmed, the pressure of hydrogen supplied to the fuel cell stack 10 is measured in S390, and it is determined in S400 whether the pressure of hydrogen supplied to the fuel cell stack 10 has decreased. If the amount of hydrogen in the fuel cell stack 10 has not changed, and it is determined that the pressure of hydrogen supplied to the fuel cell stack 10 has decreased, the supply of hydrogen to the fuel cell stack 10 is interrupted in S410.

[0135] In the event of a confirmed malfunction due to a failure to close the integrated valve 30, the supply of hydrogen to the fuel cell stack 10 shall be immediately interrupted when the pressure of hydrogen supplied to the fuel cell stack 10 decreases, in order to prevent excessive hydrogen from leaking into the atmosphere and thus ensure passenger safety.

[0136] When no pressure drop in hydrogen supplied to fuel cell stack 10 is detected, the fault is determined to be due to a failure to close integrated valve 30. However, the amount of hydrogen leaked through integrated valve 30 is negligible, and since the hydrogen concentration estimate of fuel cell stack 10 is cancelled, it is difficult to ensure the full performance of fuel cell stack 10. Therefore, the output of fuel cell stack 10 is limited in S420.

[0137] In the following text, reference will be made to Figure 6 Describe the process of using valve drive current to determine operational faults of integrated valve 30.

[0138] like Figure 6 As shown, when the integrated valve 30 is commanded to open or close in S500 and a predetermined time has elapsed in S510, the valve drive current is periodically measured in S520, and the instantaneous rate of change of the valve drive current is calculated in S540. The instantaneous rate of change of the valve drive current can be calculated by calculating a differential coefficient. Before calculating the instantaneous rate of change, noise in the valve drive current can be removed in S530 to filter the current data.

[0139] Next, in S550, it is determined whether the operation command indicated to the integrated valve 30 is an opening command, and in S560 and S570, it is determined whether the sign of the instantaneous rate of change of the valve drive current changes with time according to a predetermined time.

[0140] When the sign of the instantaneous rate of change of the valve drive current changes to the opposite sign over time and then returns to the original sign, it is determined that the integrated valve 30 is operating normally; otherwise, it is determined that the failure of the integrated valve 30 is due to an operational failure.

[0141] Reference Figure 2 When an open command is given to integrated valve 30, the valve drive current increases. When the instantaneous rate of change of the valve drive current measured after the open command is given to integrated valve 30 changes from a positive (+) value to a negative (-) value, and then changes back from a negative (-) value to a positive (+) value, it is determined in S580 that integrated valve 30 is operating normally. Furthermore, if the condition that the instantaneous rate of change of the valve drive current changes from a positive (+) value to a negative (-) value, and then changes back from a negative (-) value to a positive (+) value is not met, it is determined in S590 that a fault due to an open failure has occurred in integrated valve 30.

[0142] Furthermore, when the integrated valve 30 receives a shut-off command, the valve drive current decreases. When the instantaneous rate of change of the valve drive current measured after the integrated valve 30 receives the shut-off command changes from a negative value to a positive value, and then back to a negative value, it is determined in S580 that the integrated valve 30 is operating normally. Furthermore, if the condition that the instantaneous rate of change of the valve drive current changes from a negative value to a positive value, and then back to a negative value, is not met, it is determined in S590 that a fault due to a shut-off failure has occurred in the integrated valve 30.

[0143] When the integrated valve 30 is actually operated to open or close and the plunger of the integrated valve 30 reaches a predetermined position in the integrated valve 30 to stop, a back electromotive force is generated in the coil of the operating plunger. Therefore, from Figure 2 As can be seen from parts a and b of the graph shown, a current waveform of a predetermined shape was generated.

[0144] Specifically, when the integrated valve 30 receives an opening command, the opening operation of the integrated valve 30 is completed, thereby producing the following: Figure 2 The notched current waveform is shown in section a. Therefore, as described above, it can be determined whether the integrated valve 30 is operated to open based on information about the instantaneous rate of change of the valve drive current.

[0145] Furthermore, when the integrated valve 30 receives a closing command, the closing operation of the integrated valve 30 is completed, thereby producing the following: Figure 2 The block current waveform shown in section b. Therefore, as described above, it can be determined whether the integrated valve 30 is operated to be closed based on information about the instantaneous rate of change of the valve drive current.

[0146] When a valve drive current is applied to the integrated valve 30, but the integrated valve 30 malfunctions and jams, no valve drive current waveform is generated (e.g., Figure 2(The waveform in part a or part b).

[0147] As described above, the waveform characteristics of the valve drive current are used to determine whether the integrated valve 30 is operating properly, so that when the water level in the collector 20 is 0%, it can be determined whether hydrogen purging is being performed properly without the need to install a separate pressure sensor in the collector 20.

[0148] According to the apparatus for diagnosing valve failures in a fuel cell system disclosed herein, the operating characteristics of the integrated valve can be used to determine whether the integrated valve is operating normally. Therefore, it is possible to accurately determine whether the operation of the integrated valve is abnormal without the need to install an additional pressure sensor in the water collector, and problems caused by abnormal operation of the integrated valve can be prevented by responding immediately to abnormal operation of the integrated valve.

[0149] Although this disclosure has been described in detail, the terms or words used in the specification and appended claims should not be construed as limited to their ordinary or dictionary meaning, and the embodiments described herein and the configurations shown in the accompanying drawings are merely exemplary embodiments of this disclosure. Therefore, the scope of this disclosure is not limited to these embodiments, and various modifications and improvements made by those skilled in the art using the basic conceptual design of this disclosure as defined by the appended claims further fall within the scope of this disclosure.

Claims

1. An apparatus for diagnosing valve failures in a fuel cell system, the apparatus comprising: A water collector is configured to store water and hydrogen emitted from the fuel cell stack. An integrated valve is configured to open or close a channel through which the water and hydrogen stored in the water collector are discharged. as well as The controller is configured to: when the controller commands the opening operation of the integrated valve, cause the integrated valve to enter a forced drive mode, and determine that the integrated valve is not open based on the instantaneous rate of change of the drive current operating the integrated valve, and is further configured to: after the integrated valve enters the forced drive mode, determine that the integrated valve is faulty when the integrated valve is not open.

2. The apparatus according to claim 1, wherein, When the water level in the collector is zero, the controller commands the opening of the integrated valve. When the integrated valve is not open, the controller does not perform hydrogen concentration estimation for the fuel cell stack, and the controller does not perform zero-value correction for the hydrogen pressure sensor, which is configured to detect the hydrogen pressure supplied to the fuel cell stack.

3. The apparatus according to claim 2, wherein, When the water level in the collector is zero, the controller commands the opening of the integrated valve. When the integrated valve is open, the controller performs the hydrogen concentration estimation of the fuel cell stack, and after a set time, the controller performs the zero-value correction of the hydrogen pressure sensor.

4. The apparatus according to claim 1, wherein, When the water level in the collector is not zero, the controller commands the opening of the integrated valve. If the integrated valve is open and the water level in the collector does not drop, the controller determines that the discharge channel of the integrated valve is blocked after a set time.

5. The apparatus according to claim 1, wherein, When a command is given to close the integrated valve and the integrated valve is not closed, the controller does not perform hydrogen concentration estimation for the fuel cell stack.

6. The apparatus according to claim 5, wherein, When a command is given to close the integrated valve and the integrated valve is not closed, the controller performs the hydrogen concentration estimation of the fuel cell stack after a set time has elapsed.

7. The apparatus according to claim 1, wherein, When the integrated valve is commanded to close, and when a malfunction is determined in the integrated valve, and the pressure of the hydrogen supplied to the fuel cell stack decreases, the controller interrupts the supply of hydrogen to the fuel cell stack.

8. The apparatus according to claim 1, wherein, When the integrated valve is commanded to close, and when it is determined that the integrated valve has malfunctioned while the pressure of the hydrogen supplied to the fuel cell stack has not decreased, the controller limits the output of the fuel cell stack to less than or equal to a predetermined reference output.

9. The apparatus according to claim 1, wherein, When the integrated valve is commanded to open, and when the instantaneous rate of change of the drive current changes from a positive (+) value to a negative (-) value, and then changes from the negative (-) value back to the positive (+) value as the drive current of the integrated valve increases, the controller determines that the integrated valve is open.

10. The apparatus according to claim 1, wherein, When the integrated valve is commanded to close, and when the instantaneous rate of change of the drive current changes from a negative (-) value to a positive (+) value, and then changes from the positive (+) value to the negative (-) value again while the drive current of the integrated valve decreases, the controller determines that the integrated valve is closed.

11. The apparatus according to claim 1, wherein, When the integrated valve enters the forced drive mode, the controller commands the integrated valve to operate according to the set opening duty cycle and the number of opening operations.

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