Liquid level detection control method and device of fuel cell thermal management system and vehicle

Abstract

The application discloses a liquid level detection control method and device of a fuel cell thermal management system and a vehicle, the fuel cell thermal management system comprising an expansion water tank and a two-stage liquid level sensor arranged in the expansion water tank; the two-stage liquid level sensor comprising a first liquid level detection switch and a second liquid level detection switch; the liquid level detection control method comprising: acquiring a first switch signal output by the first liquid level detection switch and a second switch signal output by the second liquid level detection switch; determining a risk level of the fuel cell thermal management system according to a combination relationship between the first switch signal and the second switch signal; and controlling the fuel cell thermal management system to execute a corresponding control strategy according to the risk level. The liquid level detection control method provided by the application judges risk levels of different degrees through different combinations of switch signals, executes different control strategies according to different risk levels, and effectively improves the safety level of the thermal management system.

Description

Technical Field

[0001] This invention relates to the field of fuel cell control technology, and in particular to a liquid level detection and control method, device, and vehicle for a fuel cell thermal management system. Background Technology

[0002] With the rapid development of hydrogen fuel cell vehicles, the reliability and safety of their core power systems have become a key focus of the industry. Hydrogen fuel cells generate a significant amount of heat during operation, requiring an efficient and stable cooling system to maintain the stack temperature within a reasonable range to avoid performance degradation, shortened lifespan, or even thermal runaway risks. As a critical component of the cooling system, the expansion tank plays a vital role in regulating coolant volume changes and maintaining system pressure balance; its accurate level monitoring directly impacts the operational efficiency and safety of the vehicle's thermal management system.

[0003] However, existing solutions for monitoring expansion tank levels generally suffer from insufficient accuracy, weak anti-interference capabilities, and slow response times. This is especially true under the complex and variable operating conditions of hydrogen fuel cell vehicles (such as high-frequency vibration, extreme temperatures, and electromagnetic interference), where traditional level sensors are prone to false alarms or missed alarms, failing to meet the high reliability requirements of fuel cell systems for real-time level monitoring. Furthermore, existing level alarm strategies often employ a single threshold triggering mechanism, which cannot achieve tiered early warning and proactive protection against level anomalies. This may result in failure to provide timely alerts for minor fluid shortages or direct shutdown without buffering in cases of severe fluid shortages, impacting vehicle operational continuity and user experience. Summary of the Invention

[0004] This invention provides a liquid level detection and control method, device, and vehicle for a fuel cell thermal management system. By acquiring the switching signals of a dual-stage liquid level sensor installed in the expansion tank, and judging the risk level of the fuel cell thermal management system based on different combinations of switching signals, different control strategies are selected according to different risk levels. The hierarchical early warning mechanism extends the fault response window, maintains vehicle operation to the maximum extent while ensuring system safety, reduces operational losses caused by unnecessary shutdowns, and improves the safety level of the fuel cell thermal management system.

[0005] According to one aspect of the present invention, a liquid level detection and control method for a fuel cell thermal management system is provided, the fuel cell thermal management system including an expansion tank and a dual-stage liquid level sensor disposed within the expansion tank; the dual-stage liquid level sensor includes a first liquid level detection switch and a second liquid level detection switch; the liquid level detection and control method includes: Acquire the first switching signal output by the first liquid level detection switch and the second switching signal output by the second liquid level detection switch; The risk level of the fuel cell thermal management system is determined based on the combination relationship between the first switch signal and the second switch signal. The fuel cell thermal management system is controlled to execute the corresponding control strategy based on the risk level.

[0006] Optionally, before determining the risk level of the fuel cell thermal management system based on the combination relationship between the first switch signal and the second switch signal, the process includes: When the liquid level in the expansion tank drops to the first liquid level threshold, the first switch signal is in an active state. When the liquid level in the expansion tank drops to the second liquid level threshold, the second switch signal is in an active state; wherein the first liquid level threshold is greater than the second liquid level threshold.

[0007] Optionally, the risk level of the fuel cell thermal management system is determined based on the combination relationship between the first switch signal and the second switch signal, including: When both the first switch signal and the second switch signal are in an invalid state, the fuel cell thermal management system is determined to be in a normal state. When the first switch signal is valid and the second switch signal is invalid, the fuel cell thermal management system is determined to be at level one risk. When both the first switch signal and the second switch signal are in a valid state, the fuel cell thermal management system is determined to be at a level two risk level. When the first switch signal is in an invalid state and the second switch signal is in an valid state, it is determined that the dual-stage liquid level sensor is malfunctioning.

[0008] Optionally, the fuel cell thermal management system may be controlled to execute a corresponding control strategy based on the risk level, including: When the fuel cell thermal management system is in normal operation, it is controlled to operate according to a preset thermal management strategy.

[0009] Optionally, the fuel cell thermal management system may be controlled to execute a corresponding control strategy based on the risk level, including: When the fuel cell thermal management system is at the first-level risk level, it outputs a first-level liquid level alarm message and prompts the expansion tank to be replenished with liquid.

[0010] Optionally, the fuel cell thermal management system may be controlled to execute a corresponding control strategy based on the risk level, including: When the fuel cell thermal management system is at level 2 risk, the stack output power of the fuel cell is reduced, and the radiator fan is controlled to run at a preset speed; at the same time, the opening value of the three-way valve and the operating status of the water pump are collected.

[0011] Optionally, after collecting the opening value of the three-way valve and the operating status of the water pump, the following may also be included: When the opening value of the three-way valve is greater than the preset opening value and the water pump is running dry, it is determined that the coolant circulation of the fuel cell thermal management system is abnormal, and the fuel cell thermal management system is controlled to perform shutdown protection.

[0012] Optionally, the fuel cell thermal management system may be controlled to execute a corresponding control strategy based on the risk level, including: When the dual-stage liquid level sensor malfunctions, it outputs sensor malfunction information to prompt for repair of the dual-stage liquid level sensor.

[0013] According to a second aspect of the present invention, a liquid level detection and control device for a fuel cell thermal management system is provided, for executing the liquid level detection and control method for a fuel cell thermal management system as described in any one of the first aspects of the present invention, the liquid level detection and control device comprising: The acquisition module is used to acquire the first switching signal output by the first liquid level detection switch and the second switching signal output by the second liquid level detection switch; A risk level assessment module is used to determine the risk level of the fuel cell thermal management system based on the combination relationship between the first switch signal and the second switch signal. The strategy execution module is used to control the fuel cell thermal management system to execute the corresponding control strategy according to the risk level.

[0014] According to a third aspect of the present invention, a vehicle is provided, including a fuel cell thermal management system and the liquid level detection and control device described in the second aspect of the present invention.

[0015] This invention provides a liquid level detection and control method, device, and vehicle for a fuel cell thermal management system. The fuel cell thermal management system includes an expansion tank and a dual-stage liquid level sensor installed within the expansion tank. The dual-stage liquid level sensor includes a first liquid level detection switch and a second liquid level detection switch. The liquid level detection and control method includes: acquiring a first switching signal output by the first liquid level detection switch and a second switching signal output by the second liquid level detection switch; determining the risk level of the fuel cell thermal management system based on the combination relationship between the first and second switching signals; and controlling the fuel cell thermal management system to execute a corresponding control strategy based on the risk level. This invention provides a liquid level detection and control method for a fuel cell thermal management system. By acquiring the switching signals of the dual-stage liquid level sensor installed within the expansion tank and determining the risk level of the fuel cell thermal management system based on different combinations of switching signals, and selecting different control strategies according to different risk levels, the hierarchical early warning mechanism extends the fault response window, maximizing vehicle operation while ensuring system safety, reducing operational losses caused by unnecessary downtime, and improving the safety level of the fuel cell thermal management system.

[0016] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a structural block diagram of a fuel cell thermal management system provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a two-stage liquid level sensor in a fuel cell thermal management system provided in an embodiment of the present invention; Figure 3 This is a flowchart of a liquid level detection and control method for a fuel cell thermal management system provided in an embodiment of the present invention; Figure 4 This is a flowchart of another liquid level detection and control method for a fuel cell thermal management system provided in an embodiment of the present invention; Figure 5 This is a flowchart of another liquid level detection and control method for a fuel cell thermal management system provided in an embodiment of the present invention; Figure 6This is a flowchart of another liquid level detection and control method for a fuel cell thermal management system provided in an embodiment of the present invention; Figure 7 This is a flowchart of another liquid level detection and control method for a fuel cell thermal management system provided in an embodiment of the present invention; Figure 8 This is a flowchart of another liquid level detection and control method for a fuel cell thermal management system provided in an embodiment of the present invention; Figure 9 This is a flowchart of another liquid level detection and control method for a fuel cell thermal management system provided in an embodiment of the present invention; Figure 10 This is a flowchart of another liquid level detection and control method for a fuel cell thermal management system provided in an embodiment of the present invention; Figure 11 This is a block diagram of another fuel cell thermal management system liquid level detection and control device provided in an embodiment of the present invention. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0020] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0021] Figure 1 This is a structural block diagram of a fuel cell thermal management system provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a two-stage liquid level sensor in a fuel cell thermal management system provided in an embodiment of the present invention; Figure 3 This is a flowchart of a liquid level detection and control method for a fuel cell thermal management system provided in an embodiment of the present invention; see reference. Figure 1-3The present invention provides a fuel cell thermal management system including an expansion tank 1, a fuel cell stack 2, a three-way valve 3, a radiator 4, and a water pump 5; the expansion tank 1 includes a two-stage liquid level sensor 11 and a pressure cap 12; wherein, the expansion tank 1 is used to store coolant and discharge air from the system (i.e., Figure 1 The dual-stage liquid level sensor 11 in the expansion tank 1 is used to monitor the liquid level of the coolant in the expansion tank 1 in real time. During the cold start phase of the vehicle, the temperature of the fuel cell stack 2 is low, and it is desirable to heat up quickly. Therefore, the fuel cell stack 2-three-way valve 3-fuel cell stack 2 forms a small loop, bypassing the radiator 4, to achieve rapid heating of the fuel cell stack 2. During the normal operation phase, the fuel cell stack 2-three-way valve 3-radiator 4-water pump 5-fuel cell stack 2 forms a large loop. The dual-stage liquid level sensor 11 is installed on the mounting base 117. The reed switch 111 is a magnetically controlled normally closed / normally open switch. Its core consists of two alloy springs encapsulated in a sleeve. When an external magnetic field is applied, the primary liquid level spring 113 or the secondary liquid level spring 116 is magnetized and attracted to conduct. When the magnetic field disappears, it elastically resets and disconnects. When the liquid level in expansion tank 1 drops, the first float 112 falls to the first-level liquid level spring 113, the magnetic plate is attracted, the first liquid level detection switch S1 is closed, the first switch signal SW1 is in an active state, the first float 112 falls to the baffle 114, the first switch signal SW1 remains in an active state, the liquid level in expansion tank 1 continues to drop, the second float 115 falls to the second-level liquid level spring 116, the magnetic plate is attracted, the second liquid level detection switch S2 is closed, the second switch signal SW2 is in an active state.

[0022] refer to Figure 3 The liquid level detection and control method for a fuel cell thermal management system provided in this embodiment of the invention includes: S101. Obtain the first switch signal output by the first liquid level detection switch and the second switch signal output by the second liquid level detection switch.

[0023] In this embodiment, the fuel cell thermal management system includes an expansion tank 1 and a dual-stage liquid level sensor 11 disposed within the expansion tank 1. The dual-stage liquid level sensor 11 is used to detect the liquid level of the coolant in the expansion tank 1. The dual-stage liquid level sensor 11 includes a first liquid level detection switch S1 and a second liquid level detection switch S2, which are spaced apart along the height direction of the expansion tank 1 to correspond to different liquid level detection positions.

[0024] Specifically, the controller ( Figure 1(Not shown) is connected to the first liquid level detection switch S1 and the second liquid level detection switch S2 respectively, and is used to acquire the first switch signal SW1 output by the first liquid level detection switch S1 and the second switch signal SW2 output by the second liquid level detection switch S2. The first switch signal SW1 and the second switch signal SW2 are used to characterize the current state of the first liquid level detection switch S1 and the second liquid level detection switch S2 respectively, so as to determine the risk level of the fuel cell thermal management system based on the two switch signals.

[0025] S102. Determine the risk level of the fuel cell thermal management system based on the combination relationship between the first switch signal and the second switch signal.

[0026] Specifically, after acquiring the first switch signal SW1 and the second switch signal SW2, the risk level of the fuel cell thermal management system is determined based on the combination relationship between the first switch signal SW1 and the second switch signal SW2. The first switch signal SW1 and the second switch signal SW2 are used to characterize the state of the first liquid level detection switch S1 and the second liquid level detection switch S2, respectively. The controller determines the risk state corresponding to the coolant level in the expansion tank by combining and judging the valid states of the two switch signals.

[0027] S103. Control the fuel cell thermal management system to execute the corresponding control strategy according to the risk level.

[0028] Specifically, the controller generates corresponding control commands based on the currently determined risk level and sends these commands to the relevant actuators in the fuel cell thermal management system (such as the fuel cell stack 2, three-way valve 3, radiator 4, and water pump 5) to enable the fuel cell thermal management system to take appropriate measures based on different liquid level risk states. For example, when the fuel cell thermal management system is at a level one risk, the controller outputs a corresponding liquid level alarm message to prompt the user to replenish the expansion tank, etc.

[0029] This invention provides a liquid level detection and control method for a fuel cell thermal management system. By acquiring the switching signals of a dual-stage liquid level sensor installed in the expansion tank, and judging the risk level of the fuel cell thermal management system based on different combinations of switching signals, different control strategies are selected according to different risk levels. The hierarchical early warning mechanism extends the fault response window, maintains vehicle operation to the maximum extent while ensuring system safety, reduces operational losses caused by unnecessary shutdowns, and improves the safety level of the fuel cell thermal management system.

[0030] Based on the above embodiments, the present invention further refines the process of determining the risk level of the fuel cell thermal management system according to the combination relationship between the first and second switch signals. Figure 4This is a flowchart of another fuel cell thermal management system liquid level detection and control method provided in this embodiment of the invention, for reference. Figure 4 The liquid level detection and control method for a fuel cell thermal management system provided in this embodiment of the invention includes: S201. Obtain the first switch signal output by the first liquid level detection switch and the second switch signal output by the second liquid level detection switch.

[0031] S2021. When the liquid level in the expansion tank drops to the first liquid level threshold, the first switch signal is in an active state.

[0032] Specifically, in this embodiment, the dual-level liquid level sensor 11 includes a first liquid level detection switch S1, which is positioned at a first height within the expansion tank 1 to detect changes in the coolant level. A first liquid level threshold corresponds to the installation height of the first liquid level detection switch S1. When the coolant level in the expansion tank 1 is higher than the first liquid level threshold, the first liquid level detection switch S1 is not triggered and outputs an invalid first switch signal SW1. As the coolant in the expansion tank 1 is consumed, the coolant level gradually decreases. When the coolant level drops to the first liquid level threshold, the first liquid level detection switch S1 outputs an active first switch signal SW1.

[0033] S2012. When the liquid level in the expansion tank drops to the second liquid level threshold, the second switch signal is in an active state.

[0034] Specifically, in this embodiment, the dual-level liquid level sensor 11 includes a second liquid level detection switch S2, which is positioned at a second height within the expansion tank 1 to detect changes in the coolant level within the expansion tank. The second liquid level threshold corresponds to the installation height of the second liquid level detection switch S2. When the coolant level in the expansion tank 1 is higher than the second liquid level threshold, the second liquid level detection switch S2 is not triggered and outputs an invalid second switch signal SW2. As the coolant in the expansion tank 1 is consumed, the coolant level gradually decreases. When the coolant level drops to the second liquid level threshold, the second liquid level detection switch S2 outputs an active second switch signal SW2.

[0035] S202. Determine the risk level of the fuel cell thermal management system based on the combination relationship between the first switch signal and the second switch signal.

[0036] S203. Control the fuel cell thermal management system to execute the corresponding control strategy according to the risk level.

[0037] Based on the above embodiments, this invention further refines the determination of the risk level of the fuel cell thermal management system according to the combination relationship between the first switch signal and the second switch signal. Figure 5 This is a flowchart of another fuel cell thermal management system liquid level detection and control method provided in this embodiment of the invention, for reference. Figure 5 The liquid level detection and control method for a fuel cell thermal management system provided in this embodiment of the invention includes: S301. Obtain the first switch signal output by the first liquid level detection switch and the second switch signal output by the second liquid level detection switch.

[0038] S302. Determine the risk level of the fuel cell thermal management system based on the combination relationship between the first switch signal and the second switch signal.

[0039] S3021. When both the first switch signal and the second switch signal are in an invalid state, the fuel cell thermal management system is determined to be in a normal state.

[0040] Specifically, in this embodiment, after the controller acquires the first switch signal SW1 output by the first liquid level detection switch S1 and the second switch signal SW2 output by the second liquid level detection switch S2, it judges the state of the first switch signal SW1 and the second switch signal SW2 to determine the current risk level of the fuel cell thermal management system. When the coolant level in the expansion tank 1 is within the normal range, and the coolant level is higher than the first liquid level threshold and the second liquid level threshold, neither the first liquid level detection switch S1 nor the second liquid level detection switch S2 is triggered. At this time, the first switch signal SW1 output by the first liquid level detection switch S1 is in an invalid state, and the second switch signal SW2 output by the second liquid level detection switch S2 is in an invalid state. When the controller detects that both the first switch signal SW1 and the second switch signal SW2 are in an invalid state, it indicates that the coolant level in the expansion tank 1 has not dropped to the preset alarm position, and it is determined that the fuel cell thermal management system is in a normal state.

[0041] S3022. When the first switch signal is in an active state and the second switch signal is in an inactive state, the fuel cell thermal management system is determined to be at the first-level risk level.

[0042] Specifically, when the coolant level in expansion tank 1 drops to the first level threshold, the first level detection switch S1 is triggered and outputs a valid first switch signal SW1. Since the coolant level has not yet dropped to the second level threshold, the second level detection switch S2 is not triggered and outputs an invalid second switch signal SW2. After acquiring the first switch signal SW1 and the second switch signal SW2, the controller judges the combined state of the two switch signals. When the first switch signal SW1 is detected to be valid and the second switch signal SW2 is detected to be invalid, it indicates that the coolant level in expansion tank 1 has dropped to the first level threshold, but has not yet reached the low level state corresponding to the second level threshold. At this time, the coolant level is within the first-level warning range, and the fuel cell thermal management system is determined to be at the first-level risk level.

[0043] S3023. When both the first switch signal and the second switch signal are in a valid state, the fuel cell thermal management system is determined to be at the second-level risk level.

[0044] Specifically, as the coolant in expansion tank 1 is continuously consumed, the liquid level in expansion tank 1 continues to drop. When the coolant level drops to the second liquid level threshold, the second liquid level detection switch S2 is triggered and outputs a valid second switch signal SW2. Since the second liquid level threshold is lower than the first liquid level threshold, the first liquid level detection switch S1 remains triggered and continues to output a valid first switch signal SW1. After acquiring the first switch signal SW1 and the second switch signal SW2, the controller judges the combined state of the two switch signals. When both the first switch signal SW1 and the second switch signal SW2 are detected to be valid, it indicates that the coolant level in expansion tank 1 has dropped to the second liquid level threshold, and the fuel cell thermal management system is determined to be at level two risk.

[0045] S3024. When the first switch signal is in an invalid state and the second switch signal is in an valid state, it is determined that there is an abnormality in the dual-stage liquid level sensor.

[0046] Specifically, the first liquid level detection switch S1 and the second liquid level detection switch S2 are spaced apart along the height direction of the expansion tank 1, and the first liquid level threshold is greater than the second liquid level threshold. Therefore, during the normal decrease of the coolant level in the expansion tank 1, the first liquid level detection switch S1 should be triggered before the second liquid level detection switch S2, that is, the first switch signal SW1 should be in an active state first. When the controller acquires the first switch signal SW1 and the second switch signal SW2, if it detects that the first switch signal SW1 is in an inactive state while the second switch signal SW2 is in an active state, it indicates that the second liquid level detection switch S2 has detected a low liquid level state, while the first liquid level detection switch S1 has not detected the corresponding liquid level change. This signal combination does not conform to the normal detection pattern of the dual-stage liquid level sensor. Therefore, it is determined that the dual-stage liquid level sensor 11 is abnormal.

[0047] S303. Control the fuel cell thermal management system to execute the corresponding control strategy according to the risk level.

[0048] Based on the above embodiments, the embodiments of the present invention further refine the control strategy for controlling the fuel cell thermal management system to execute corresponding controls according to the risk level. Figure 6 This is a flowchart of another fuel cell thermal management system liquid level detection and control method provided in this embodiment of the invention, for reference. Figure 6 The liquid level detection and control method for a fuel cell thermal management system provided in this embodiment of the invention includes: S401. Obtain the first switch signal output by the first liquid level detection switch and the second switch signal output by the second liquid level detection switch.

[0049] S402. Determine the risk level of the fuel cell thermal management system based on the combination relationship between the first switch signal and the second switch signal.

[0050] S403. When both the first switch signal and the second switch signal are in an invalid state, the fuel cell thermal management system is determined to be in a normal state.

[0051] S404. When the fuel cell thermal management system is in normal condition, control the fuel cell thermal management system to operate according to the preset thermal management strategy.

[0052] Specifically, when the controller determines that the fuel cell thermal management system is in a normal state based on the first switch signal SW1 and the second switch signal SW2, it indicates that the coolant level in the expansion tank 1 is within the normal range, and neither the first level detection switch S1 nor the second level detection switch S2 detects any abnormal level changes. At this time, the controller does not perform protective controls such as alarms, power reduction, or shutdown based on abnormal level conditions. Instead, it controls the fuel cell thermal management system to operate according to a preset thermal management strategy. For example, the preset thermal management strategy may include adjusting the coolant circulation, heat dissipation capacity, and related thermal management components according to the operating status of the fuel cell system to maintain the fuel cell stack within a suitable operating temperature range.

[0053] Based on the above embodiments, the embodiments of the present invention further refine the control strategy for controlling the fuel cell thermal management system to execute corresponding controls according to the risk level. Figure 7 This is a flowchart of another fuel cell thermal management system liquid level detection and control method provided in this embodiment of the invention, for reference. Figure 7 The liquid level detection and control method for a fuel cell thermal management system provided in this embodiment of the invention includes: S501. Obtain the first switch signal output by the first liquid level detection switch and the second switch signal output by the second liquid level detection switch.

[0054] S502. Determine the risk level of the fuel cell thermal management system based on the combination relationship between the first switch signal and the second switch signal.

[0055] S503. When the first switch signal is in an active state and the second switch signal is in an inactive state, the fuel cell thermal management system is determined to be at the first-level risk level.

[0056] S504. When the fuel cell thermal management system is at the first-level risk level, output a first-level liquid level alarm message and prompt the expansion tank to be replenished.

[0057] Specifically, when the controller determines that the fuel cell thermal management system is at a Level 1 risk level based on the first switch signal SW1 and the second switch signal SW2, it indicates that the coolant level in the expansion tank 1 has dropped to the first level threshold. At this time, the first level detection switch S1 is active, while the second level detection switch S2 remains inactive. Since the current coolant level is below the preset safe level but has not yet reached the severe low-coolant state corresponding to the second level threshold, the controller controls the fuel cell thermal management system to output a Level 1 level alarm message to remind the user to pay attention to the current coolant level. Furthermore, the Level 1 level alarm message can be output through a display device, indicator light, sound prompt device, or other human-machine interface device to prompt the user to check the expansion tank 1 and perform coolant replenishment as needed.

[0058] Based on the above embodiments, the embodiments of the present invention further refine the control strategy for controlling the fuel cell thermal management system to execute corresponding controls according to the risk level. Figure 8 This is a flowchart of another fuel cell thermal management system liquid level detection and control method provided in this embodiment of the invention, for reference. Figure 8 The liquid level detection and control method for a fuel cell thermal management system provided in this embodiment of the invention includes: S601. Obtain the first switch signal output by the first liquid level detection switch and the second switch signal output by the second liquid level detection switch.

[0059] S602. Determine the risk level of the fuel cell thermal management system based on the combination relationship between the first switch signal and the second switch signal.

[0060] S603. When both the first switch signal and the second switch signal are in a valid state, the fuel cell thermal management system is determined to be at the second-level risk level.

[0061] S604. When the fuel cell thermal management system is at level 2 risk, reduce the fuel cell stack output power and control the radiator fan to run at a preset speed; at the same time, collect the opening value of the three-way valve and the operating status of the water pump.

[0062] Specifically, when the controller determines that the fuel cell thermal management system is at a level two risk based on the first switch signal SW1 and the second switch signal SW2, it indicates that the coolant level in the expansion tank 1 has dropped to the second level threshold, and the current coolant storage is insufficient, which may affect the normal operation of the fuel cell thermal management system. At this time, the controller controls the fuel cell stack 2 to reduce its output power to reduce the heat generated during fuel cell operation and reduce the thermal load of the cooling system. At the same time, it controls the fan of the radiator 4 to run at a preset speed to improve the radiator's heat dissipation capacity, so that the heat generated by the fuel cell stack can be released in a timely manner. Furthermore, while executing the above control strategy, the controller acquires the operating status information of the cooling circulation components in the fuel cell thermal management system, such as the opening value of the three-way valve 3 and the operating status of the water pump 5. The opening value of the three-way valve 3 is used to reflect the adjustment status of the coolant flow path, and the operating status of the water pump 5 is used to reflect the coolant circulation drive status, so as to further determine whether the coolant circulation is abnormal based on the operating status information.

[0063] Based on the above embodiments, the embodiments of the present invention further refine the control strategy for controlling the fuel cell thermal management system to execute corresponding controls according to the risk level. Figure 9 This is a flowchart of another fuel cell thermal management system liquid level detection and control method provided in this embodiment of the invention, for reference. Figure 9The liquid level detection and control method for a fuel cell thermal management system provided in this embodiment of the invention includes: S701. Obtain the first switch signal output by the first liquid level detection switch and the second switch signal output by the second liquid level detection switch.

[0064] S702. Determine the risk level of the fuel cell thermal management system based on the combination relationship between the first switch signal and the second switch signal.

[0065] S703. When both the first switch signal and the second switch signal are in a valid state, the fuel cell thermal management system is determined to be at the second-level risk level.

[0066] S704. When the fuel cell thermal management system is at level 2 risk, reduce the fuel cell stack output power and control the radiator fan to run at a preset speed; at the same time, collect the opening value of the three-way valve and the operating status of the water pump.

[0067] S705. When the opening value of the three-way valve is greater than the preset opening value and the water pump is running dry, it is determined that the coolant circulation of the fuel cell thermal management system is abnormal, and the fuel cell thermal management system is controlled to perform shutdown protection.

[0068] Specifically, when the fuel cell thermal management system is at level two risk, the controller further acquires the opening value of the three-way valve 3 and the operating status of the water pump 5, and determines the coolant circulation status based on these parameters. When the opening value of the three-way valve 3 is greater than the preset opening value, it indicates that the three-way valve 3 is in a large opening state, and there may be a large flow regulation requirement in the coolant flow path. At the same time, when the water pump 5 is detected to be running dry, it indicates that the water pump 5 has failed to establish effective coolant circulation. At this time, combining the opening status of the three-way valve 3 and the operating status of the water pump 5, it can be determined that there is an abnormality in the coolant circulation in the fuel cell thermal management system. When the abnormality in coolant circulation is determined, the controller controls the fuel cell thermal management system to execute shutdown protection to stop the fuel cell system from continuing to operate, avoiding the temperature rise of the fuel cell stack 2 due to the inability of coolant to circulate normally, thereby reducing the risk of system damage.

[0069] Based on the above embodiments, the embodiments of the present invention further refine the control strategy for controlling the fuel cell thermal management system to execute corresponding controls according to the risk level. Figure 10 This is a flowchart of another fuel cell thermal management system liquid level detection and control method provided in this embodiment of the invention, for reference. Figure 10 The liquid level detection and control method for a fuel cell thermal management system provided in this embodiment of the invention includes: S801. Obtain the first switch signal output by the first liquid level detection switch and the second switch signal output by the second liquid level detection switch.

[0070] S802. Determine the risk level of the fuel cell thermal management system based on the combination relationship between the first switch signal and the second switch signal.

[0071] S803. When the first switch signal is in an invalid state and the second switch signal is in an valid state, it is determined that there is an abnormality in the dual-stage liquid level sensor.

[0072] S804. When the dual-stage liquid level sensor malfunctions, output sensor malfunction information to prompt for maintenance of the dual-stage liquid level sensor.

[0073] Specifically, when the first switch signal SW1 is detected to be invalid while the second switch signal SW2 is valid, it indicates that the signal states of the first liquid level detection switch S1 and the second liquid level detection switch S2 do not conform to the preset liquid level change pattern, and the controller determines that the dual-stage liquid level sensor 11 is malfunctioning. When the malfunction of the dual-stage liquid level sensor 11 is determined, the controller outputs sensor malfunction information to prompt the user or maintenance personnel to inspect and repair the dual-stage liquid level sensor 11. The sensor malfunction information can be output through a display device, an alarm device, or a vehicle control terminal.

[0074] Based on the same inventive concept Figure 11 This is a block diagram of another fuel cell thermal management system liquid level detection and control device provided in an embodiment of the present invention, with reference to... Figure 11 This invention provides a liquid level detection and control device for a fuel cell thermal management system, used to execute the liquid level detection and control method for the fuel cell thermal management system in any of the above embodiments. The liquid level detection and control device includes: The acquisition module 100 is used to acquire the first switch signal output by the first liquid level detection switch and the second switch signal output by the second liquid level detection switch.

[0075] The risk level assessment module 200 is used to determine the risk level of the fuel cell thermal management system based on the combination relationship between the first switch signal and the second switch signal.

[0076] The strategy execution module 300 is used to control the fuel cell thermal management system to execute the corresponding control strategy according to the risk level.

[0077] The liquid level detection and control device for a fuel cell thermal management system provided in this embodiment of the invention can achieve the same technical effect as the liquid level detection and control method for a fuel cell thermal management system provided in any of the above embodiments of the invention, therefore, it will not be described in detail here.

[0078] Based on the same inventive concept, embodiments of the present invention also provide a vehicle, including a fuel cell thermal management system and the liquid level detection and control device in the above-described embodiments.

[0079] The vehicle provided in this embodiment of the invention can achieve the same technical effect as the liquid level detection and control device of the fuel cell thermal management system provided in the above-described embodiment of the invention, therefore, it will not be described in detail here.

[0080] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0081] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A liquid level detection and control method for a fuel cell thermal management system, characterized in that, The fuel cell thermal management system includes an expansion tank and a dual-stage liquid level sensor disposed within the expansion tank; the dual-stage liquid level sensor includes a first liquid level detection switch and a second liquid level detection switch; the liquid level detection and control method includes: Acquire the first switching signal output by the first liquid level detection switch and the second switching signal output by the second liquid level detection switch; The risk level of the fuel cell thermal management system is determined based on the combination relationship between the first switch signal and the second switch signal. The fuel cell thermal management system is controlled to execute the corresponding control strategy based on the risk level.

2. The liquid level detection and control method for the fuel cell thermal management system according to claim 1, characterized in that, Before determining the risk level of the fuel cell thermal management system based on the combination relationship between the first switch signal and the second switch signal, the process includes: When the liquid level in the expansion tank drops to the first liquid level threshold, the first switch signal is in an active state. When the liquid level in the expansion tank drops to the second liquid level threshold, the second switch signal is in an active state; wherein the first liquid level threshold is greater than the second liquid level threshold.

3. The liquid level detection and control method for the fuel cell thermal management system according to claim 2, characterized in that, Determining the risk level of the fuel cell thermal management system based on the combination relationship between the first switch signal and the second switch signal includes: When both the first switch signal and the second switch signal are in an invalid state, the fuel cell thermal management system is determined to be in a normal state. When the first switch signal is valid and the second switch signal is invalid, the fuel cell thermal management system is determined to be at level one risk. When both the first switch signal and the second switch signal are in a valid state, the fuel cell thermal management system is determined to be at a level two risk level. When the first switch signal is in an invalid state and the second switch signal is in an valid state, it is determined that the dual-stage liquid level sensor is malfunctioning.

4. The liquid level detection and control method for the fuel cell thermal management system according to claim 3, characterized in that, Based on the risk level, the fuel cell thermal management system is controlled to execute corresponding control strategies, including: When the fuel cell thermal management system is in normal operation, it is controlled to operate according to a preset thermal management strategy.

5. The liquid level detection and control method for the fuel cell thermal management system according to claim 3, characterized in that, Based on the risk level, the fuel cell thermal management system is controlled to execute corresponding control strategies, including: When the fuel cell thermal management system is at the first-level risk level, it outputs a first-level liquid level alarm message and prompts the expansion tank to be replenished with liquid.

6. The liquid level detection and control method for the fuel cell thermal management system according to claim 3, characterized in that, Based on the risk level, the fuel cell thermal management system is controlled to execute corresponding control strategies, including: When the fuel cell thermal management system is at level 2 risk, the stack output power of the fuel cell is reduced, and the radiator fan is controlled to run at a preset speed; at the same time, the opening value of the three-way valve and the operating status of the water pump are collected.

7. The liquid level detection and control method for the fuel cell thermal management system according to claim 6, characterized in that, After collecting the opening value of the three-way valve and the operating status of the water pump, the following is also included: When the opening value of the three-way valve is greater than the preset opening value and the water pump is running dry, it is determined that the coolant circulation of the fuel cell thermal management system is abnormal, and the fuel cell thermal management system is controlled to perform shutdown protection.

8. The liquid level detection and control method for the fuel cell thermal management system according to claim 3, characterized in that, Based on the risk level, the fuel cell thermal management system is controlled to execute corresponding control strategies, including: When the dual-stage liquid level sensor malfunctions, it outputs sensor malfunction information to prompt for repair of the dual-stage liquid level sensor.

9. A liquid level detection and control device for a fuel cell thermal management system, characterized in that, A liquid level detection and control method for executing the fuel cell thermal management system according to any one of claims 1 to 8, wherein the liquid level detection and control device comprises: The acquisition module is used to acquire the first switching signal output by the first liquid level detection switch and the second switching signal output by the second liquid level detection switch; A risk level assessment module is used to determine the risk level of the fuel cell thermal management system based on the combination relationship between the first switch signal and the second switch signal. The strategy execution module is used to control the fuel cell thermal management system to execute the corresponding control strategy according to the risk level.

10. A vehicle, characterized in that, It includes a fuel cell thermal management system and the liquid level detection and control device as described in claim 9.

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