Fuel cell system and cooling system blockage detection and exhaust method thereof

Abstract

The invention relates to the technical field of fuel cells, and discloses a fuel cell system which comprises a galvanic pile, and an air system and a hydrogen system which are respectively connected with a cathode and an anode of the galvanic pile, the air system comprises an air compressor, and the air compressor is connected with a cathode inlet of the electric pile; the hydrogen system comprises a gas-water separator; the gas-water separator is connected with an anode outlet of the electric pile; the cooling system is used for controlling the temperature of the electric pile. The end A of the first three-way valve is connected with the air compressor, the cooling pipeline can be purged after cooling liquid in the cooling pipeline is emptied, it is ensured that the cooling pipeline is kept dry, and after purging is completed, the blockage condition of the cooling system can be tested through the air compressor conveying air to the cooling pipeline and the shutdown time of the air compressor. And it is ensured that filled cooling liquid can smoothly flow in the cooling pipeline, and the burden of the water pump is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a fuel cell system and a cooling system blockage detection and exhaust method thereof. Background Art

[0002] A fuel cell system is a power generation system that takes the fuel cell stack as the core, and is composed of a fuel supply and circulation system, an oxidant supply system, a water and heat management system, a control system, etc.

[0003] The fuel cell stack will generate a lot of heat during operation, and the cooling system is required to control its temperature to ensure that the fuel cell stack always maintains an appropriate temperature range. When the cooling system needs to replace the coolant or the bench test is completed, the coolant in the cooling pipeline needs to be drained (the cooling pipeline needs to be disassembled to discharge the coolant). In order to avoid coolant residue in the pipeline, the cooling pipeline needs to be purged. The traditional purging method is to loosen the cooling pipeline joint and move the gas cylinder for purging, which is time-consuming and labor-intensive. Frequent disassembly and assembly of the cooling system can easily cause the cooling pipeline and seals to loosen, which may cause leakage problems later. Summary of the invention

[0004] The present invention aims to solve the above-mentioned problems and provides a fuel cell system and a cooling system blockage detection and exhaust method thereof, so as to solve the problems that the existing fuel cell system needs to dismantle and replace the cooling pipeline every time it is purged, which causes the cooling pipeline to loosen and leak, and the sealing effect is poor, and each time the coolant is added, the expansion water tank needs to be opened for manual addition, which is time-consuming and labor-intensive.

[0005] To achieve this object, the present invention adopts the following technical solutions: A fuel cell system, comprising: A fuel cell stack and an air system and a hydrogen system connected to the anode and cathode of the fuel cell stack respectively; The air system includes an air compressor, and the air compressor is connected to the cathode inlet of the fuel cell stack; The hydrogen system includes a gas-water separator, which is connected to the anode outlet of the fuel cell stack; Also included is a cooling system for controlling the temperature of the battery stack, the cooling system comprising a water pump connected by a cooling pipeline, a first three-way valve, and an expansion water tank connected to the cooling pipeline; The input end of the water pump is connected to the battery stack, and the output end is connected to the B end of the first three-way valve. The water pump is used to provide circulation power for the coolant; The A end of the first three-way valve is connected to the output end of the air compressor for introducing air into the cooling pipeline, and the C end of the first three-way valve is connected to the fuel cell stack; The liquid inlet of the expansion water tank is connected to the liquid discharge end of the gas-water separator, and the liquid outlet is connected to the cooling pipeline, so as to replenish the cooling liquid to the cooling pipeline.

[0006] Preferably, the expansion water tank is also connected to the input end of the air compressor to extract air from the expansion water tank.

[0007] Preferably, the cooling system further comprises: A first liquid discharge valve, connected between the air compressor and the A end of the first three-way valve; A first exhaust valve is connected between the battery stack and the water pump; a second exhaust valve connected between the input end of the air compressor and the expansion water tank; The second liquid discharge valve is connected between the gas-water separator and the liquid inlet of the expansion water tank.

[0008] Preferably, the cooling system further comprises: A second three-way valve, end a connected to end C of the first three-way valve, and end b connected to the fuel cell stack; A radiator connected between the C end of the first three-way valve and the C end of the second three-way valve; A deionizer is connected between the end b of the second three-way valve and the cell stack.

[0009] Preferably, the liquid outlet of the expansion water tank is connected between the end b of the second three-way valve and the deionizer.

[0010] Preferably, the air system further comprises: An air intake valve connected between the output end of the air compressor and the cathode inlet of the fuel cell stack; A back pressure valve is connected to the cathode outlet of the fuel cell stack.

[0011] Preferably, the hydrogen system further comprises: An ejector, connected to the anode inlet of the battery stack and the gas-water separator respectively; The third exhaust valve is connected to the gas-water separator.

[0012] A cooling system blockage detection method, applied to the fuel cell system, comprises the following control steps: Get the vehicle running status; If the vehicle is in a shutdown state, obtain the shutdown time of the air compressor; Drain the coolant in the cooling system, and the air compressor will purge the cooling pipeline within the preset time; After the purge is completed, disconnect the power supply of the air compressor and record the duration of the air compressor stopping after the power is cut off; Determine the blockage of the cooling system based on the duration of the shutdown and downtime; Among them, the shutdown time is the time it takes for the air compressor to change from a low speed state to a zero speed state.

[0013] Preferably, draining the coolant in the cooling system comprises the following control steps: Close the air inlet valve, the first exhaust valve, the second drain valve and the C end of the first three-way valve; Open the first drain valve and adjust the opening of the second three-way valve to 60%-70%; Start the water pump and adjust the speed of the water pump to the medium speed state. When the liquid level in the expansion water tank is 0, adjust the speed of the water pump to the low speed state; The water pump is controlled to maintain a low speed state within a preset period, and the water pump power supply is disconnected after the preset period ends to complete the discharge of coolant in the cooling system.

[0014] Preferably, purging the cooling pipeline includes the following control steps: After the water pump speed reaches 0, close the first discharge valve and the B end of the first three-way valve; Open the first exhaust valve and adjust the opening of the second three-way valve to 50% opening value; Start the air compressor, adjust the speed of the air compressor to a high-speed operation state, and detect the humidity of the air discharged from the first exhaust valve; When the gas humidity is less than the preset humidity, the cooling pipeline is purged.

[0015] Preferably, recording the stop time of the air compressor comprises the following steps: Adjust the speed of the air compressor to low speed operation; Disconnect the power supply of the air compressor and record the time it takes for the air compressor to change from a low-speed operation state to a zero speed, which is recorded as the stop time.

[0016] Preferably, if the stop time is shorter than the shutdown time, it is determined that the cooling system is blocked, otherwise no blockage occurs.

[0017] A cooling system exhaust method, applied to the fuel cell system, comprises the following control steps: Get the coolant pressure in the cooling pipeline in real time; Calculate the pressure fluctuation rate of the coolant, and determine whether the cooling system needs to be vented based on the pressure fluctuation rate and a preset fluctuation threshold; If the coolant pressure fluctuation rate is greater than a preset fluctuation threshold, it is determined that the cooling system needs to be vented.

[0018] Preferably, when the cooling system needs to be exhausted, the following control steps are included: Obtain the vehicle's operating power and determine the vehicle's operating status; Among them, the vehicle operation state includes a high-power operation state, a low-power operation state and a shutdown state; The opening value of the second exhaust valve is adjusted according to the running state of the vehicle to complete the exhaust of the cooling system.

[0019] Preferably, if the vehicle is in a high-power running state, the following exhaust control steps are included: Set the lowering valve opening value, minimum opening value and pressure threshold; The second drain valve is closed, the opening of the second exhaust valve is adjusted to a first preset opening value, and the air pressure in the expansion tank is obtained. If the air pressure in the expansion tank is less than the pressure threshold, the second exhaust valve is closed; If the air pressure in the expansion water tank is greater than the pressure threshold, the opening value of the drop valve is adjusted downward based on the first preset opening value to obtain the air pressure in the expansion water tank, and the above adjustment steps are repeated until the air pressure in the expansion water tank is less than the pressure threshold, and the second exhaust valve is closed; If the opening value of the second exhaust valve is adjusted to the minimum opening value, the air pressure in the expansion tank is greater than the pressure threshold, and the current opening of the second exhaust valve is maintained to exhaust air until the air pressure in the expansion tank is less than the pressure threshold, and the second exhaust valve is closed.

[0020] Preferably, if the vehicle is in a low-power operating state, the following exhaust control steps are included: Open the second liquid discharge valve, and adjust the opening of the second exhaust valve to a second preset opening value; Wherein, the second preset opening value is greater than the first preset opening value; The second exhaust valve is maintained at a second preset opening value to exhaust air until the air pressure in the expansion tank is less than a pressure threshold, and the second exhaust valve is closed.

[0021] Preferably, if the vehicle is in a stopped state, the following exhaust control steps are included: Close the air inlet valve, end A of the first three-way valve and the second drain valve; Open the first drain valve and the second exhaust valve and start the air compressor, and adjust the speed of the air compressor to a low-speed operation state; Maintaining the second exhaust valve at a third preset opening value to exhaust air until the air pressure in the expansion tank is less than a pressure threshold, and then closing the second exhaust valve; The third preset opening value is greater than the second preset opening value.

[0022] The contribution of the present invention is that the present invention is connected to the air compressor through the A end of the first three-way valve, and the cooling pipeline can be purged after the coolant in the cooling pipeline is emptied to ensure that the cooling pipeline remains dry. On the other hand, after the purging is completed, the blockage of the cooling system can be tested by supplying air to the cooling pipeline through the air compressor and the downtime of the air compressor itself, ensuring that the filled coolant can flow smoothly in the cooling pipeline, reducing the burden on the water pump.

[0023] The liquid inlet of the expansion water tank is connected to the discharge end of the gas-water separator, which can guide the liquid in the gas-water separator into the expansion water tank, thereby ensuring that the coolant in the cooling pipeline is always sufficient. There is no need to manually open the expansion water tank to add coolant in a short period of time. The fuel cell system can replenish the coolant automatically during operation, saving maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic structural diagram of a fuel cell system of the present invention; Figure 2 is a schematic structural diagram of another embodiment of a fuel cell system of the present invention; Figure 3 It is a schematic flow chart of a cooling system blockage detection method of the present invention; Figure 4 It is a schematic diagram of a flow chart of judging whether the cooling system needs to be exhausted according to the present invention; Figure 5 It is a schematic diagram of the process of the cooling system of the present invention completing exhaust according to the running state of the vehicle and the opening value of the second exhaust valve; Among them: battery stack 10; Air system 20, air compressor 21, air intake valve 22, back pressure valve 23; Hydrogen system 30, gas-water separator 31, ejector 32, third exhaust valve 33; Cooling system 40 , cooling pipeline 41 , water pump 42 , first three-way valve 43 , expansion water tank 44 , first drain valve 45 , first exhaust valve 46 , second exhaust valve 47 , second drain valve 48 , second three-way valve 49 , radiator 410 , deionizer 411 . DETAILED DESCRIPTION

[0025] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The drawings provide embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing the embodiments of the present invention and are not intended to limit this application.

[0027] It is understood that the terms "first", "second", etc. used in this application can be used in this article to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from another element. It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element, or connected to the other element through an intermediate element. In addition, the "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc. if there is a transmission of electrical signals or data between the connected objects.

[0028] When used herein, the singular forms "a", "a person" and "the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" etc. specify the presence of stated features, wholes, steps, operations, components, parts or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof.

[0029] like Figure 1 As shown, a fuel cell system comprises: A fuel cell stack 10 and an air system 20 and a hydrogen system 30 connected to the cathode and anode of the fuel cell stack 10, respectively; The air system 20 includes an air compressor 21, and the air compressor 21 is connected to the cathode inlet of the fuel cell stack 10; The hydrogen system 30 includes a gas-water separator 31, and the gas-water separator 31 is connected to the anode outlet of the fuel cell stack 10; It also includes a cooling system 40 for controlling the temperature of the fuel cell stack 10, wherein the cooling system 40 includes a water pump 42 connected by a cooling pipeline 41, a first three-way valve 43, and an expansion water tank 44 connected to the cooling pipeline 41; The input end of the water pump 42 is connected to the fuel cell stack 10, and the output end is connected to the B end of the first three-way valve 43. The water pump 42 is used to provide circulation power for the coolant; The A end of the first three-way valve 43 is connected to the output end of the air compressor 21 for introducing air into the cooling pipeline 41, and the C end of the first three-way valve 43 is connected to the fuel cell stack 10; The liquid inlet of the expansion water tank 44 is connected to the liquid discharge end of the gas-water separator 31 , and the liquid outlet is connected to the cooling pipeline 41 , so as to replenish the cooling liquid to the cooling pipeline 41 .

[0030] To further explain, the air compressor 21 is used to provide the air required for the reaction to the cathode of the fuel cell stack 10. The hydrogen system 30 also includes a hydrogen cylinder, which can provide the hydrogen required for the reaction to the anode of the fuel cell stack 10. The waste gas after the reaction (mainly hydrogen, nitrogen and water vapor) will be discharged at the anode outlet of the fuel cell stack 10, and the exhausted gas will enter the gas-water separator 31 for gas-water separation. Liquid water will remain at the bottom of the gas-water separator 31. The gas will circulate through the ejector 32 to enter the anode of the fuel cell stack 10 to participate in the reaction. The cooling system 40 is used to maintain the temperature of the fuel cell stack 10. The various components in the cooling system 40 are connected by a cooling pipe 41. The cooling pipe 41 is filled with coolant. When the coolant flows through the fuel cell stack 10, it will take away part of the heat generated by the fuel cell stack 10, thereby ensuring that the fuel cell stack 10 can be stabilized within the required temperature range.

[0031] To further explain, in this embodiment, the A end of the first three-way valve 43 is connected to the output end of the air compressor 21, so that the air system 20 is connected to the cooling system 40, and the air compressor 21 can pass air into the cooling system 40 (during the operation of the fuel cell system, the A end of the first three-way valve 43 remains closed). Specifically, when the cooling system 40 needs to replace the coolant or the bench test is completed (the A end of the first three-way valve 43 is opened), the coolant in the cooling pipeline 41 needs to be emptied. In order to avoid coolant residue in the pipeline, the cooling pipeline 41 needs to be purged. The traditional purging method is to loosen the joint of the cooling pipeline 41 and carry the gas cylinder in. The purging is time-consuming and labor-intensive, and the frequent disassembly and assembly of the cooling system 40 may easily lead to the loosening of the cooling pipeline 41 and the seals, which may easily cause leakage problems later. The present invention is connected to the air compressor 21 through the A end of the first three-way valve 43. After the coolant in the cooling pipeline 41 is drained from the first drain valve 45, the cooling pipeline 41 can be purged to ensure that the cooling pipeline 41 remains dry. On the other hand, after the purging is completed, air can be transported to the cooling pipeline 41 through the air compressor 21 and the blockage of the cooling system 40 can be tested in combination with the downtime of the air compressor 21 itself, to ensure that the filled coolant can flow smoothly in the cooling pipeline 41, thereby reducing the burden on the water pump 42.

[0032] The liquid inlet of the expansion water tank 44 is connected to the discharge end of the gas-water separator 31, and the liquid in the gas-water separator 31 can be introduced into the expansion water tank 44, thereby ensuring that the coolant in the cooling pipeline 41 is always kept in a sufficient state. There is no need to manually open the expansion water tank 44 to add coolant in a short period of time. The fuel cell system can replenish the coolant automatically during operation, saving maintenance costs.

[0033] like Figure 2 As shown, in another embodiment of the present invention, the expansion water tank 44 is also connected to the input end of the air compressor 21 to extract the air in the expansion water tank 44.

[0034] Specifically, the air compressor 21 generates suction during operation, thereby extracting the gas in the expansion water tank 44 and completing the exhaust process of the expansion water tank 44. Regardless of whether the coolant is replaced or the coolant is introduced from the gas-water separator 31, air will be mixed into the coolant to form bubbles, thereby affecting the operation efficiency of the water pump 42, which will cause damage to the water pump 42 over time. The present invention extracts the air above the expansion water tank 44 through the air compressor 21, so that the air pressure in the expansion water tank 44 is reduced, and the bubbles in the coolant will overflow and gather at the top of the expansion water tank 44 and then be continuously extracted by the air compressor 21, thereby ensuring that the gas content in the coolant is not too high, ensuring that the temperature control fluctuation of the coolant does not exceed the preset range, and also playing a role in protecting the water pump 42.

[0035] Further explanation, the cooling system 40 also includes: A first liquid discharge valve 45 is connected between the air compressor 21 and the A end of the first three-way valve 43; A first exhaust valve 46 is connected between the fuel cell stack 10 and the water pump 42; A second exhaust valve 47 is connected between the input end of the air compressor 21 and the expansion water tank 44; The second liquid discharge valve 48 is connected between the gas-water separator 31 and the liquid inlet of the expansion water tank 44 .

[0036] Specifically, it also includes a humidity detector connected to the outlet end of the first exhaust valve 46, which is used to detect the humidity of the gas exhausted from the first exhaust valve 46, the first drain valve 45 is used to discharge the coolant in the cooling pipeline 41, the first exhaust valve 46 is used to discharge the air introduced into the cooling system 40 by the air compressor 21 (used to detect the blockage of the cooling system 40), the second exhaust valve 47 is used to control the flow of gas in the expansion water tank 44 into the air compressor 21, the second drain valve 48 is used to control the liquid in the gas-water separator 31 to enter the expansion water tank 44, and the second drain valve 48 is intermittently opened, and the specific opening cycle time can be determined according to the power of the fuel cell system. The higher the power, the shorter the opening cycle time interval, and vice versa, the opening cycle time interval is longer.

[0037] Further explanation, the cooling system 40 also includes: A second three-way valve 49, end a is connected to end C of the first three-way valve 43, and end b is connected to the fuel cell stack 10; The radiator 410 is connected between the C end of the first three-way valve 43 and the C end of the second three-way valve 49; The deionizer 411 is connected between the end b of the second three-way valve 49 and the fuel cell stack 10 .

[0038] The setting of the second three-way valve 49 divides the cooling system 40 into a large circulation loop and a small circulation loop. Specifically, the small circulation loop includes a water pump 42, the C end of the first three-way valve 43 and the a end of the second three-way valve 49. The coolant in the small circulation loop does not pass through the radiator 410, but directly enters the battery stack 10 and absorbs the heat of the battery stack 10, thereby rapidly increasing the temperature of the coolant (a simple small circulation loop is generally suitable for the initial startup stage). The large circulation loop includes a water pump 42, the C end of the first three-way valve 43, the radiator 410 and the c end of the second three-way valve 49. The coolant in the large circulation loop passes through the radiator 410 to take away part of the heat, thereby ensuring that the temperature of the coolant is not too high and always keeps consistent with the temperature in the battery stack 10, ensuring that the battery stack 10 is maintained within an appropriate temperature range. The deionizer 411 can remove ions in the coolant to ensure that the battery stack 10 is not disturbed.

[0039] To further illustrate this embodiment, the liquid outlet of the expansion water tank 44 is connected between the end b of the second three-way valve 49 and the deionizer 411 .

[0040] Since the gas-water separator 31 will intermittently discharge liquid into the expansion water tank 44, the liquid from the gas-water separator 31 will contain metal ions, so a deionizer 411 is set at the liquid outlet of the expansion water tank 44 to ensure that the coolant added from the expansion water tank 44 to the cooling pipeline 41 meets the usage standards.

[0041] Further explanation, the air system 20 also includes: An air intake valve 22 is connected between the output end of the air compressor 21 and the cathode inlet of the fuel cell stack 10; The back pressure valve 23 is connected to the cathode outlet of the fuel cell stack 10 .

[0042] The intake valve 22 is used to control the flow of cathode air entering the fuel cell stack 10 , and the back pressure valve 23 is used to control the cathode pressure of the fuel cell stack 10 .

[0043] To further illustrate, the hydrogen system 30 also includes: The ejector 32 is connected to the anode inlet of the stack 10 and the gas-water separator 31 respectively; The third exhaust valve 33 is connected to the gas-water separator 31 .

[0044] The third exhaust valve 33 is used to discharge the gas in the gas-water separator 31. Specifically, as the hydrogen is circulated, the concentration of hydrogen in the gas-water separator 31 will decrease, and the concentration of nitrogen will continue to increase. When the nitrogen concentration reaches a preset value, it is necessary to open the third exhaust valve 33 to discharge the gas in the gas-water separator 31 to ensure that the circulating hydrogen that subsequently enters the fuel cell stack 10 will not affect the reaction efficiency of the fuel cell stack 10.

[0045] like Figure 3 As shown, another embodiment of the present invention discloses a cooling system blockage detection method, which is applied to the fuel cell system, and specifically includes the following control steps: Get the vehicle running status; If the vehicle is in a shutdown state, the shutdown time of the air compressor 21 is obtained (the test average value can be taken according to data statistics, which not only ensures the representativeness of the data but also avoids misjudgment caused by a single data error); The coolant in the cooling system 40 is drained, and the air compressor 21 purges the cooling pipeline 41 within a preset time; After the purging is completed, the power supply of the air compressor 21 is disconnected, and the shutdown time of the air compressor 21 after the power is disconnected is recorded; Determine the blockage of the cooling system 40 according to the stoppage time and the shutdown time; The shutdown duration is the duration for the air compressor 21 to change from a low speed state (consistent with the speed when the air compressor 21 is powered off) to a speed of 0.

[0046] The present embodiment discloses a cooling system blockage detection method, which can detect the blockage of the cooling system 40. Specifically, it is necessary to first determine the running state of the vehicle. After determining that the vehicle is in a stopped state, the coolant in the cooling pipeline 41 is emptied and the cooling pipeline 41 is purged to ensure that no coolant remains in the cooling pipeline 41 (which will not affect the subsequent measurement of the stop time of the air compressor 21). After the purging is completed, the power supply of the air compressor 21 is disconnected, and the stop time of the air compressor 21 is recorded (the stop time is the time from the power off of the air compressor 21 to the air compressor 21 speed being 0). By comparing the stop time with the shutdown time, the blockage condition of the cooling pipeline 41 can be determined. Specifically, when blockage occurs in the cooling pipeline 41 (possible impurities and sediments), the gas resistance in the pipeline will increase, and the gas resistance will cause the speed of the air compressor 21 to decrease rapidly (at this time, the air compressor 21 has been powered off, and the pump holding in the low-speed operation state will not cause damage to the air compressor 21), resulting in the stop time of the air compressor 21 being less than the shutdown time, and then determining that blockage has occurred in the cooling system 40 and maintenance is required.

[0047] To further illustrate this embodiment, draining the coolant in the cooling system 40 includes the following control steps: Close the intake valve 22, the first exhaust valve 46, the second drain valve 48 and the C end of the first three-way valve 43; Open the first drain valve 45 and adjust the opening of the second three-way valve 49 to 60%-70%; Start the water pump 42, adjust the speed of the water pump 42 to a medium speed state, and when the liquid level in the expansion water tank 44 is 0, adjust the speed of the water pump 42 to a low speed state; The water pump 42 is controlled to maintain a low speed state within a preset period, and the power supply of the water pump 42 is disconnected after the preset period ends, thereby completing the discharge of the coolant in the cooling system 40.

[0048] By closing the intake valve 22, the first exhaust valve 46, the second drain valve 48 and the C end of the first three-way valve 43 (at this time, the A end and the B end are connected), it can be ensured that the coolant does not enter the cathode of the fuel cell stack 10. The opening of the second three-way valve 49 is adjusted to an opening value of 60%-70%. This is because when the fuel cell system is in operation, it mainly dissipates heat from the coolant through the radiator 410 (large circulation loop). About 60%-70% of the coolant passes through the radiator 410, and 30%-40% of the coolant directly enters the second three-way valve 49 through the small circulation loop. The opening of the second three-way valve 49 is adjusted to an opening value of 60%-70% (consistent with the coolant ratio in the large circulation loop and the small circulation loop) to ensure that the water pump 42 can smoothly discharge the coolant in the cooling pipe 41 out of the cooling system 40.

[0049] It should be noted here that the range of the opening value is 0-100%, wherein when the second three-way valve 49 is at the minimum opening value, the c end of the second three-way valve 49 is closed, and the a end and the b end are connected; when the second three-way valve 49 is at the maximum opening value, the a end of the second three-way valve 49 is closed, and the b end and the c end are connected; when the opening value is between the maximum opening value and the minimum opening value, the a end, the b end and the c end of the second three-way valve 49 are all connected (the opening range that can be achieved by the opening control of the A end, the B end and the C end of the first three-way valve 43 is consistent with that of the second three-way valve 49, which will not be repeated here).

[0050] The water pump 42 is adjusted to a medium speed state (1000rpm-3000rpm), and the coolant in the cooling pipe 41 and the expansion water tank 44 is continuously discharged from the first drain valve 45. When the liquid level in the expansion water tank 44 is 0, it indicates that there is no coolant in the expansion water tank 44. At this time, it is only necessary to discharge the remaining coolant in the cooling pipe 41. In order to ensure that the water pump 42 does not idle, the water pump 42 is adjusted from the medium speed state to the low speed state (less than 1000rpm), and the water pump 42 is controlled to maintain a low speed state within a preset time (the preset time is set to 15s-20s. Even if the water pump 42 idles during this time period, it will not be damaged. It is within the acceptable idling time range of the water pump 42) to ensure that the coolant in the cooling pipe 41 is drained.

[0051] To further illustrate this embodiment, purging the cooling pipeline 41 includes the following control steps: After the speed of the water pump 42 reaches 0, close the first liquid discharge valve 45 and the B end of the first three-way valve 43; Open the first exhaust valve 46 and adjust the opening of the second three-way valve 49 to 50% opening value; Start the air compressor 21, adjust the speed of the air compressor 21 to a high-speed operation state, and detect the humidity of the air discharged from the first exhaust valve 46; When the gas humidity is less than the preset humidity, the purging of the cooling pipeline 41 is completed.

[0052] Specifically, close the first drain valve 45 and the B end of the first three-way valve 43 to ensure that air is not discharged from the first drain valve 45 through the water pump 42, and adjust the opening of the second three-way valve 49 to a 50% opening value. At this time, half of the gas enters the fuel cell stack 10 from the large circulation loop, and the other half of the gas enters the fuel cell stack 10 from the small circulation loop, ensuring that the airflow can be evenly distributed to the large circulation loop and the small circulation loop, and ensuring that each pipeline can be smoothly detected for blockage.

[0053] The speed of the air compressor 21 is adjusted to a high-speed operation state (200000 rpm), so that the air compressor 21 can quickly purge the cooling pipeline 41, so that the coolant remaining in the cooling pipeline 41 is carried out of the cooling pipeline 41 by the strong airflow. By detecting the humidity at the outlet end of the first exhaust valve 46, the coolant residue in the cooling pipeline 41 can be determined. When the gas humidity is less than the preset humidity, it indicates that the cooling pipeline 41 has been dried, and subsequent blockage detection can be performed.

[0054] To further illustrate this embodiment, recording the stop time of the air compressor 21 includes the following steps: Adjust the speed of the air compressor 21 to a low-speed operation state; The power supply of the air compressor 21 is disconnected, and the time it takes for the rotation speed of the air compressor 21 to change from a low-speed operation state to a zero speed is recorded as the stop time.

[0055] Specifically, to protect the air compressor 21, before the formal power-off detection, the speed of the air compressor 21 needs to be adjusted to a low-speed operation state (20000rpm-40000rpm). After the power supply of the air compressor 21 is disconnected, the speed of the air compressor 21 will gradually decrease until it reaches 0. The time from the speed of the air compressor 21 at the time of power failure to the speed of 0 is recorded as the stop time. If there is a blockage in the cooling system 40, the air pressure will increase. Since the air compressor 21 has been powered off, the air compressor 21 will have a pump-blocking phenomenon at this time. The speed of the air compressor 21 will decrease rapidly (causing the stop time to be less than the stop time in the unblocked state), so as to determine whether there is a blockage in the cooling system 40. Further explanation, if the stop time is less than the stop time, it is judged that the cooling system 40 is blocked, otherwise, no blockage occurs.

[0056] like Figure 4 As shown, another embodiment of the present invention discloses a cooling system exhaust method, which is applied to the fuel cell system, and specifically includes the following control steps: Real-time acquisition of the pressure of the coolant in the cooling pipeline 41; Calculating the pressure fluctuation rate of the coolant, and judging whether the cooling system 40 needs to be vented according to the pressure fluctuation rate and a preset fluctuation threshold; If the pressure fluctuation rate of the coolant is greater than the preset fluctuation threshold, it is determined that the cooling system 40 needs to be vented.

[0057] The present embodiment discloses a cooling system venting method, which monitors the pressure fluctuation rate of the coolant (calculates the absolute value of the pressure at the current moment and the rated pressure, and then divides the obtained absolute value by the rated pressure to obtain the fluctuation rate at the current moment) and combines it with a preset fluctuation threshold to determine whether the cooling system 40 needs to be vented.

[0058] like Figure 5 As shown, further explanation of this embodiment, when the cooling system 40 needs to be exhausted, the following control steps are included: Obtain the vehicle's operating power and determine the vehicle's operating status; Among them, the vehicle operation state includes a high-power operation state, a low-power operation state and a shutdown state; The opening value of the second exhaust valve 47 is adjusted according to the running state of the vehicle to complete the exhaust of the cooling system 40.

[0059] Specifically, the vehicle is in different operating states and requires different air flows, so the opening value of the second exhaust valve 47 needs to be adjusted according to the specific state of the vehicle to ensure that the air compressor 21 can smoothly extract the gas in the expansion water tank 44.

[0060] To further illustrate this embodiment, if the vehicle is in a high-power operation state, the following exhaust control steps are included: Set the lowering valve opening value, minimum opening value and pressure threshold; The second drain valve 48 is closed, and the opening of the second exhaust valve 47 is adjusted to a first preset opening value to obtain the air pressure in the expansion tank 44. If the air pressure in the expansion tank 44 is less than the pressure threshold, the second exhaust valve 47 is closed; If the air pressure in the expansion water tank 44 is greater than the pressure threshold, the opening value of the step-down valve is adjusted downward based on the previous opening value (here, the first preset opening value) to obtain the air pressure in the expansion water tank 44, and the above adjustment steps are repeated until the air pressure in the expansion water tank 44 is less than the pressure threshold, and the second exhaust valve 47 is closed; If the opening value of the second exhaust valve 47 is adjusted to the minimum opening value (5%-10%), the air pressure in the expansion tank 44 is greater than the pressure threshold, and the current opening of the second exhaust valve 47 is maintained for exhaust until the air pressure in the expansion tank 44 is less than the pressure threshold, and the second exhaust valve 47 is closed.

[0061] Specifically, if the vehicle is in a high-power operating state, the cathode of the fuel cell stack 10 has a large demand for air, the air compressor 21 has a high speed and a strong extraction force. In order to prevent the air compressor 21 from extracting the coolant in the expansion water tank 44, the present invention controls the opening value of the second exhaust valve 47. Specifically, the opening of the second exhaust valve 47 is controlled to be at a first preset opening value (25%-35%). Since there is a lot of gas and a high pressure in the expansion water tank 44 at this time, the gas in the expansion water tank 44 will be smoothly introduced into the input end of the air compressor 21 through the second exhaust valve 47. A pressure sensor is installed in the expansion water tank 44. The air pressure in the expansion water tank 44 is detected by the pressure sensor. If the measured air pressure in the expansion water tank 44 is still greater than the pressure threshold, the first preset opening value is adjusted downward according to the valve opening value (3%-5%). The reason why the opening of the second exhaust valve 47 is adjusted downward here is As the gas in the expansion water tank 44 gradually decreases, in order to prevent the cooling water in the expansion water tank 44 from being pumped away by the air compressor 21, the opening value of the second exhaust valve 47 is reduced, thereby reducing the extraction force of the air compressor 21 on the expansion water tank 44. Further explanation, each time the opening value is adjusted downward according to the valve-dropping opening value, it is necessary to maintain the current opening value for 2s (including the state of the first preset opening value). As long as it is monitored within 2s that the air pressure in the expansion water tank 44 is lower than the pressure threshold, the second exhaust valve 47 can be closed. If the air pressure in the expansion water tank 44 is still higher than the pressure threshold within 2s, the opening value of the second exhaust valve 47 is adjusted downward again according to the valve-dropping opening value, and the above adjustment steps are repeated (the limit of the downward adjustment of the second exhaust valve 47 is the minimum opening value) until it is monitored that the air pressure in the expansion water tank 44 is lower than the pressure threshold, then the second exhaust valve 47 can be closed, thereby completing the exhaust of the cooling system 40 under the high-power state of the vehicle.

[0062] To further illustrate this embodiment, if the vehicle is in a low-power operation state, the following exhaust control steps are included: Open the second liquid discharge valve 48 and adjust the opening of the second exhaust valve 47 to a second preset opening value; Wherein, the second preset opening value is greater than the first preset opening value; The second exhaust valve 47 is maintained at a second preset opening value to exhaust gas until the air pressure in the expansion tank 44 is less than the pressure threshold, and then the second exhaust valve 47 is closed.

[0063] Specifically, when the vehicle is in a low-power operating state, the cathode of the fuel cell stack 10 does not require much air, and the suction force at the input end of the air compressor 21 is less than the suction force of the air compressor 21 under high power. At this time, the opening of the second exhaust valve 47 is adjusted to a second preset opening value (50%-60%), and the second preset opening value is maintained until the air pressure in the expansion water tank 44 is less than the pressure threshold, thereby completing the exhaust of the cooling system 40 under low power of the vehicle.

[0064] To further illustrate this embodiment, if the vehicle is in a stopped state, the following exhaust control steps are included: Close the air inlet valve 22, the A end of the first three-way valve 43 and the second drain valve 48; Open the first liquid discharge valve 45 and the second exhaust valve 47 and start the air compressor 21, and adjust the speed of the air compressor 21 to a low-speed operation state; Maintain the second exhaust valve 47 at a third preset opening value to exhaust air until the air pressure in the expansion tank 44 is less than the pressure threshold, and then close the second exhaust valve 47; The third preset opening value is greater than the second preset opening value.

[0065] Specifically, when the vehicle is in a shutdown state, the cathode of the battery stack 10 does not need air to participate in the reaction, so the intake valve 22 is closed. In order to prevent the air at the output end of the air compressor 21 from mixing into the coolant, the A end of the first three-way valve 43 is closed to ensure that air does not enter the cooling line 41 through the first three-way valve 43. The closing of the second drain valve 48 can ensure that no new liquid flows from the gas-water separator 31 into the expansion water tank 44 (to avoid the entry of air). The air compressor 21 is adjusted to a low-speed operation state (generally 15000rpm-20000rpm to avoid excessive suction force of the air compressor 21) and the expansion water tank 44 is filled with air. Coolant is extracted), the first drain valve 45 and the second exhaust valve 47 are opened, and the gas in the expansion water tank 44 will flow into the input end of the air compressor 21 through the second exhaust valve 47 (100% opening value, at this time the fuel cell stack 10 does not need air to participate in the reaction, and since the intake valve 22 is in a closed state, there is no need to worry about the water vapor in the expansion water tank 44 entering the fuel cell stack 10. At this time, the second exhaust valve 47 can be fully opened to quickly extract the gas in the expansion water tank 44), and then discharged from the output end of the air compressor 21 to the first drain valve 45, and the extracted gas is discharged through the first drain valve 45, thereby completing the exhaust when the vehicle is in a stopped state.

[0066] Although the present invention is disclosed through the above embodiments, the protection scope of the present invention is not limited thereto. Without departing from the concept of the present invention, any deformation, replacement, etc. made to the above components shall fall within the scope of the claims of the present invention.

Claims

1. A fuel cell system, characterized in that: include: A fuel cell stack and an air system and a hydrogen system connected to the anode and cathode of the fuel cell stack respectively; The air system includes an air compressor, and the air compressor is connected to the cathode inlet of the fuel cell stack; The hydrogen system includes a gas-water separator, which is connected to the anode outlet of the fuel cell stack; Also included is a cooling system for controlling the temperature of the battery stack, the cooling system comprising a water pump connected by a cooling pipeline, a first three-way valve, and an expansion water tank connected to the cooling pipeline; The input end of the water pump is connected to the battery stack, and the output end is connected to the B end of the first three-way valve. The water pump is used to provide circulation power for the coolant; The A end of the first three-way valve is connected to the output end of the air compressor for introducing air into the cooling pipeline, and the C end of the first three-way valve is connected to the fuel cell stack; The liquid inlet of the expansion water tank is connected to the liquid discharge end of the gas-water separator, and the liquid outlet is connected to the cooling pipeline, so as to replenish the cooling liquid to the cooling pipeline.

2. A fuel cell system according to claim 1, characterized in that: The expansion water tank is also connected to the input end of the air compressor to extract the air in the expansion water tank.

3. A fuel cell system according to claim 2, characterized in that: The cooling system further comprises: A first liquid discharge valve, connected between the air compressor and the A end of the first three-way valve; A first exhaust valve is connected between the battery stack and the water pump; a second exhaust valve connected between the input end of the air compressor and the expansion water tank; The second liquid discharge valve is connected between the gas-water separator and the liquid inlet of the expansion water tank.

4. A fuel cell system according to claim 1, characterized in that: The cooling system further comprises: A second three-way valve, end a connected to end C of the first three-way valve, and end b connected to the fuel cell stack; A radiator connected between the C end of the first three-way valve and the C end of the second three-way valve; A deionizer is connected between the end b of the second three-way valve and the battery stack.

5. A fuel cell system according to claim 4, characterized in that: The liquid outlet of the expansion water tank is connected between the end b of the second three-way valve and the deionizer.

6. A fuel cell system according to claim 1, characterized in that: The air system further comprises: An air intake valve connected between the output end of the air compressor and the cathode inlet of the fuel cell stack; A back pressure valve is connected to the cathode outlet of the fuel cell stack.

7. A fuel cell system according to claim 1, characterized in that: The hydrogen system further comprises: An ejector is connected to the anode inlet of the battery stack and the gas-water separator respectively; The third exhaust valve is connected to the gas-water separator.

8. A cooling system blockage detection method, applied to the fuel cell system according to any one of claims 1 to 7, characterized in that: The control steps include: Get the vehicle running status; If the vehicle is in a shutdown state, obtain the shutdown time of the air compressor; Drain the coolant in the cooling system, and the air compressor will purge the cooling pipeline within the preset time; After the purge is completed, disconnect the power supply of the air compressor and record the duration of the air compressor stopping after the power is cut off; Determine the blockage of the cooling system based on the duration of the shutdown and downtime; Among them, the shutdown time is the time it takes for the air compressor to change from a low speed state to a zero speed state.

9. A cooling system blockage detection method according to claim 8, characterized in that: Draining the coolant from the cooling system involves the following control steps: Close the air inlet valve, the first exhaust valve, the second drain valve and the C end of the first three-way valve; Open the first drain valve and adjust the opening of the second three-way valve to 60%-70%; Start the water pump and adjust the speed of the water pump to the medium speed state. When the liquid level in the expansion water tank is 0, adjust the speed of the water pump to the low speed state; The water pump is controlled to maintain a low speed state within a preset period, and the water pump power supply is disconnected after the preset period ends to complete the discharge of coolant in the cooling system.

10. A cooling system blockage detection method according to claim 9, characterized in that: Purging the cooling line includes the following control steps: After the water pump speed reaches 0, close the first discharge valve and the B end of the first three-way valve; Open the first exhaust valve and adjust the opening of the second three-way valve to 50%; Start the air compressor, adjust the speed of the air compressor to a high-speed operation state, and detect the humidity of the air discharged from the first exhaust valve; When the gas humidity is less than the preset humidity, the cooling pipeline is purged.

11. A cooling system blockage detection method according to claim 10, characterized in that: Recording the downtime of the air compressor includes the following steps: Adjust the speed of the air compressor to low speed operation; Disconnect the power supply of the air compressor and record the time it takes for the air compressor to change from a low-speed operation state to a zero speed, which is recorded as the stop time.

12. A cooling system blockage detection method according to claim 11, characterized in that: If the stop time is shorter than the shutdown time, it is judged that the cooling system is blocked, otherwise no blockage occurs.

13. A cooling system exhaust method, applied to the fuel cell system according to any one of claims 1 to 7, characterized in that: The control steps include: Get the coolant pressure in the cooling pipeline in real time; Calculate the pressure fluctuation rate of the coolant, and determine whether the cooling system needs to be vented based on the pressure fluctuation rate and a preset fluctuation threshold; If the coolant pressure fluctuation rate is greater than a preset fluctuation threshold, it is determined that the cooling system needs to be vented.

14. A cooling system exhaust method according to claim 13, characterized in that: When the cooling system needs to be exhausted, the following control steps are included: Obtain the vehicle's operating power and determine the vehicle's operating status; Among them, the vehicle operation state includes a high-power operation state, a low-power operation state and a shutdown state; The opening value of the second exhaust valve is adjusted according to the running state of the vehicle to complete the exhaust of the cooling system.

15. A cooling system exhaust method according to claim 14, characterized in that: If the vehicle is in high-power operation, the exhaust control steps include the following: Set the lowering valve opening value, minimum opening value and pressure threshold; The second drain valve is closed, the opening of the second exhaust valve is adjusted to a first preset opening value, and the air pressure in the expansion tank is obtained. If the air pressure in the expansion tank is less than the pressure threshold, the second exhaust valve is closed; If the air pressure in the expansion water tank is greater than the pressure threshold, the opening value of the drop valve is adjusted downward based on the previous opening value to obtain the air pressure in the expansion water tank, and the above adjustment steps are repeated until the air pressure in the expansion water tank is less than the pressure threshold, and the second exhaust valve is closed; If the opening value of the second exhaust valve is adjusted to the minimum opening value, the air pressure in the expansion tank is greater than the pressure threshold, and the current opening of the second exhaust valve is maintained to exhaust air until the air pressure in the expansion tank is less than the pressure threshold, and the second exhaust valve is closed.

16. A cooling system exhaust method according to claim 15, characterized in that: If the vehicle is in low power operation, the exhaust control steps include: Open the second liquid discharge valve, and adjust the opening of the second exhaust valve to a second preset opening value; Wherein, the second preset opening value is greater than the first preset opening value; The second exhaust valve is maintained at a second preset opening value to exhaust air until the air pressure in the expansion tank is less than a pressure threshold, and the second exhaust valve is closed.

17. A cooling system exhaust method according to claim 16, characterized in that: If the vehicle is in a stopped state, the exhaust control steps include the following: Close the air inlet valve, end A of the first three-way valve and the second drain valve; Open the first drain valve and the second exhaust valve and start the air compressor, and adjust the speed of the air compressor to a low-speed operation state; Maintaining the second exhaust valve at a third preset opening value to exhaust air until the air pressure in the expansion tank is less than a pressure threshold, and then closing the second exhaust valve; The third preset opening value is greater than the second preset opening value.

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