A fuel cell engine

Abstract

This invention provides a fuel cell engine, belonging to the field of fuel cell technology, which solves the safety hazard caused by negative pressure forming on both sides of the hydrogen-air interface within the fuel cell stack after shutdown in existing technologies. The device includes a fuel cell stack, a gas storage tank, an air pump, an air compressor, first to fourth shut-off valves, and a controller. The air inlet of the fuel cell stack is connected to the output of the air compressor via the first shut-off valve, and to the outlet of the gas storage tank via the second shut-off valve. Its air outlet is connected to the air pump via the third shut-off valve, and to the vehicle's exhaust pipe via the fourth shut-off valve. The controller receives a fuel cell shutdown command and controls the first to fourth shut-off valves to close. It periodically monitors whether negative pressure forms on both sides of the hydrogen-air interface within the fuel cell stack. Once negative pressure forms, it controls the second and third shut-off valves to open, and the air pump operates at a speed matching the negative pressure. Monitoring continues until the negative pressure disappears, at which point the air pump and the second and third shut-off valves are shut down. This device effectively improves the reliability of the fuel cell.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and more particularly to a fuel cell engine. Background Technology

[0002] With the worsening of the global climate, the advantages of on-board fuel cell engines as a pollution-free clean energy source have become increasingly apparent. However, after shutdown, the fuel cell stack in the on-board fuel cell engine will experience negative pressure on both sides of the hydrogen-air interface due to the system's sealing and thermal expansion and contraction characteristics.

[0003] The membrane electrode assembly (MEA) of the fuel cell stack is sensitive to hydrogen leakage. If the pressure on the hydrogen side is higher than that on the air side, hydrogen will permeate through the MEA and enter the air side, causing a mixture of hydrogen and air. This can easily generate local high temperatures, leading to catalytic combustion in a localized area on the surface of the MEA, which can burn through the MEA and damage the entire fuel cell stack, or even cause an explosion, posing a safety hazard. Summary of the Invention

[0004] Based on the above analysis, the present invention aims to provide a fuel cell engine to solve the safety hazard caused by the formation of negative pressure on both sides of the hydrogen-air interface in the fuel cell stack after shutdown in the prior art.

[0005] On one hand, embodiments of the present invention provide a fuel cell engine, including a fuel cell stack, a gas storage tank storing non-reactive gases, a gas pump, an air compressor, a first shut-off valve to a fourth shut-off valve, and a controller;

[0006] The air inlet of the fuel cell stack is connected to the output end of the air compressor via the first shut-off valve, and to the air outlet of the air storage tank via the second shut-off valve. Its air outlet is connected to the air pump via the third shut-off valve, and to the vehicle exhaust pipe via the fourth shut-off valve.

[0007] The controller is used to receive a fuel cell shutdown command and control all four shut-off valves (first to fourth) to close; and to periodically monitor whether a negative pressure is formed on both sides of the hydrogen-air mixture in the fuel cell stack. Once a negative pressure is formed, the controller controls the second and third shut-off valves to open, and the gas pump operates at a speed matching the negative pressure. The controller monitors again until the negative pressure disappears, and then shuts off the gas pump and the second and third shut-off valves.

[0008] The beneficial effects of the above technical solution are as follows: By adding a branch at both the air inlet and outlet of the reactor, namely a gas storage tank (containing non-reactive gas) and a second shut-off valve, an air pump and a third shut-off valve, combined with the gas replenishment operation after shutdown controlled by the controller, the negative pressure caused by factors such as sealing and thermal expansion and contraction after the system is shut down can be effectively avoided, thus not affecting the next startup. This not only improves the reliability of the system, but also enhances user-friendliness.

[0009] Based on the aforementioned engine improvements, the gas storage tank stores at least one of nitrogen or an inert gas.

[0010] Furthermore, the controller further includes:

[0011] The data acquisition unit obtains the air pressure at the air inlet of the fuel cell stack and sends it to the data processing and control unit;

[0012] The data processing and control unit is used to receive a fuel cell shutdown command and control all of the first to fourth shut-off valves to close; and to periodically monitor whether the pressure difference between the air pressure at the air inlet of the fuel cell stack and the target air pressure exceeds a set threshold range. If it does, the second and third shut-off valves are opened, and the air pump is controlled to operate at a speed matching the pressure difference until the absolute value of the pressure difference drops below the set value, at which point the air pump and the second and third shut-off valves are closed.

[0013] Furthermore, the data acquisition unit further includes:

[0014] The first pressure sensor is located on the inner wall of the pipe at the air inlet of the fuel cell stack, and is used to obtain the air pressure at the air inlet of the fuel cell stack at the current moment.

[0015] Furthermore, the data processing and control unit executes the following program:

[0016] Upon receiving the fuel cell shutdown command, control all four shut-off valves (first to fourth) to close.

[0017] Regularly monitor whether the pressure difference between the air pressure at the air inlet of the fuel cell stack and the target air pressure exceeds the set threshold range. If it does, proceed to the next step; otherwise, end the current monitoring cycle.

[0018] The second and third shut-off valves are opened simultaneously, and the air pump is started.

[0019] Adjust the air pump to operate at a speed that matches the pressure difference, monitor it again until the pressure difference drops to 0, and then turn off the air pump, the second shut-off valve, and the third shut-off valve.

[0020] Furthermore, the data acquisition unit also includes:

[0021] The second pressure sensor is located on the inner wall of the pipe at the air exhaust outlet of the fuel cell stack, and is used to obtain the air pressure of the exhaust air exiting the stack at the current moment;

[0022] The third pressure sensor is located on the inner wall of the pipe at the hydrogen exhaust outlet of the fuel cell stack, and is used to obtain the pressure of the hydrogen exhaust gas exiting the stack at the current moment.

[0023] Furthermore, the data processing and control unit also executes the following program:

[0024] Obtain the pressure of the exhaust air and exhaust hydrogen at the current moment, respectively;

[0025] Based on the changes in the pressure of the exhaust air and the exhaust hydrogen during the set time period, the system identifies whether there may be leaks on the hydrogen side or the air side of the fuel cell stack. If the identification result indicates a leak on the hydrogen side of the fuel cell stack, an alarm message is issued. If the identification result indicates a leak on the air side of the fuel cell stack, the second and third shut-off valves are opened, the air pump is started, and the air pump speed is adjusted so that the pressure of the exhaust air is always equal to the pressure of the exhaust hydrogen until the fuel cell engine starts.

[0026] Furthermore, the data acquisition unit also includes an ambient temperature sensor located outside the fuel cell stack; and,

[0027] The data processing and control unit also executes the following program:

[0028] The ambient temperature is collected by the ambient temperature sensor to identify whether there is a possibility of thermal expansion and contraction inside the fuel cell stack. If so, proceed to the next step; otherwise, monitor periodically whether a negative pressure is formed on both sides of the hydrogen-air interface inside the fuel cell stack.

[0029] Identify whether the pressure of the exhaust air from the reactor is equal to the pressure of the exhaust hydrogen from the reactor. If they are not equal, immediately open the second and third shut-off valves and start the air pump. Adjust the air pump speed to make the pressure of the exhaust air from the reactor equal to the pressure of the exhaust hydrogen from the reactor. Then close the air pump and the second and third shut-off valves and re-identify whether there is any possibility of thermal expansion and contraction.

[0030] Furthermore, the data acquisition unit also includes:

[0031] A hydrogen concentration sensor is installed on the inner wall of the pipe at the hydrogen inlet of the fuel cell stack to obtain the concentration of hydrogen entering the stack.

[0032] An oxygen concentration sensor is installed on the inner wall of the duct at the air inlet of the fuel cell stack to obtain the oxygen concentration in the incoming air.

[0033] Furthermore, it also includes a fifth shut-off valve; among which,

[0034] The hydrogen inlet of the fuel cell stack is also connected to the outlet of the gas storage tank via a fifth shut-off valve.

[0035] The controller is also used to control the second and fifth shut-off valves to open after receiving a shutdown command from the fuel cell, until the data collected by the hydrogen concentration sensor and oxygen concentration sensor are all lower than the set value, and then control the first to fifth shut-off valves to close.

[0036] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0037] 1. A structure and procedure for mitigating negative pressure have been added, namely a gas storage tank containing nitrogen or inert gas, a second shut-off valve, a third shut-off valve, and an air pump. Automatic pressure replenishment is achieved by filling the tank with gas to prevent negative pressure from forming during long-term storage of the vehicle.

[0038] 2. This avoids failure due to large hydrogen-air pressure difference during restart.

[0039] 3. It does not affect customer perception and improves user-friendliness.

[0040] The summary section is provided to present the chosen concepts in a simplified form, which will be further described in the detailed description below. The summary section is not intended to identify essential or necessary features of this disclosure, nor is it intended to limit the scope of this disclosure. Attached Figure Description

[0041] The above and other objects, features and advantages of this disclosure will become more apparent from the accompanying drawings, in which like reference numerals generally denote like parts.

[0042] Figure 1 A schematic diagram of the fuel cell engine composition in Example 1 is shown;

[0043] Figure 2 A schematic diagram of the main connections of the fuel cell engine in Example 2 is shown.

[0044] Figure label:

[0045] 1- First shut-off valve; 2- Second shut-off valve; 3- Third shut-off valve; 4- Fourth shut-off valve; 5- Gas storage tank; 6- First pressure sensor; 7- Fuel cell stack; 8- Gas pump; DCDC- DC-DC converter module; CVM- Fuel cell monitoring instrument. Detailed Implementation

[0046] Embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art.

[0047] The term "comprising" and its variations as used herein signify open inclusion, i.e., "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "at least partially based on". The terms "one example embodiment" and "one embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "first", "second", etc., may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0048] Example 1

[0049] One embodiment of the present invention discloses a fuel cell engine, such as Figure 1 As shown, it includes an electric stack, a gas storage tank containing non-reactive gases, an air pump, an air compressor, first to fourth shut-off valves, and a controller.

[0050] The air inlet of the fuel cell stack is connected to the output end of the air compressor via the first shut-off valve, and to the air outlet of the air tank via the second shut-off valve. Its air outlet is connected to the air pump via the third shut-off valve, and to the vehicle exhaust pipe via the fourth shut-off valve.

[0051] The controller is used to receive a fuel cell shutdown command and control all four shut-off valves (first to fourth) to close; and to periodically monitor whether a negative pressure is formed on both sides of the hydrogen-air mixture in the fuel cell stack. Once a negative pressure is formed, the controller controls the second and third shut-off valves to open, and the gas pump operates at a speed matching the negative pressure. The controller monitors again until the negative pressure disappears, and then shuts off the gas pump and the second and third shut-off valves.

[0052] The control terminals of the air pump and the first to fourth shut-off valves are all connected to the output terminal of the controller.

[0053] Specifically, in addition to Example 2, the method for monitoring whether a negative pressure is formed on both sides of the hydrogen-air interface within the fuel cell stack in the controller can also be found in patents CN201810840722.6 or CN202111079826.8. The operating speed of the gas pump can be obtained through laboratory calibration.

[0054] The above description omits the hydrogen control circuit and coolant control circuit of the fuel cell engine, and mainly focuses on the improvement of the air control circuit, which will be understood by those skilled in the art.

[0055] Compared with the prior art, the fuel cell engine provided in this embodiment adds a branch at both the air inlet and outlet of the stack, namely a gas storage tank (containing non-reactive gases), a second shut-off valve, an air pump, and a third shut-off valve. Combined with the gas replenishment operation after shutdown controlled by the controller, it can effectively avoid the negative pressure caused by factors such as sealing and thermal expansion and contraction after the system is shut down, so as not to affect the next startup. This not only improves the reliability of the system, but also enhances user-friendliness.

[0056] Example 2

[0057] An improvement upon Example 1 is made in that the gas storage tank contains at least one of nitrogen or an inert gas. That is, the gas storage tank is a nitrogen tank or an inert gas tank. The inert gas includes at least one of helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe), or a combination of several.

[0058] Preferably, the controller further includes a data acquisition unit and a data processing and control unit connected in sequence.

[0059] The data acquisition unit obtains the air pressure at the air inlet of the fuel cell stack and sends it to the data processing and control unit.

[0060] The data processing and control unit is used to receive a fuel cell shutdown command and control all four shut-off valves (first to fourth shut-off valves) to close. It also periodically monitors whether the pressure difference between the air pressure at the air inlet of the fuel cell stack and the target air pressure exceeds a set threshold range (by measuring whether a negative pressure is formed on both sides of the hydrogen and air in the fuel cell stack). If the pressure difference exceeds the threshold, the unit opens the second and third shut-off valves and controls the air pump to operate at a speed matching the pressure difference until the absolute value of the pressure difference drops below the set value. Then, the unit closes the air pump and the second and third shut-off valves.

[0061] Preferably, the data acquisition unit further includes a first pressure sensor, such as... Figure 2 As shown.

[0062] The first pressure sensor is located on the inner wall of the pipe at the air inlet of the fuel cell stack, and is used to obtain the air pressure at the air inlet of the fuel cell stack at the current moment.

[0063] Preferably, the data processing and control unit includes a display module. The display module's screen shows air pressure data collected by the first pressure sensor after the fuel cell is shut down, including the pressure and its change over time.

[0064] Preferably, the data processing and control unit executes the following program:

[0065] S1. After receiving the fuel cell shutdown command, control the first to fourth shut-off valves to close.

[0066] S2. Periodically monitor whether the pressure difference between the air pressure at the air inlet of the fuel cell stack and the target air pressure exceeds the set threshold range. If it does, proceed to the next step; otherwise, end this round of monitoring.

[0067] S3. Control the second and third shut-off valves to open simultaneously, and start the air pump;

[0068] S4. Adjust the air pump to operate at a speed that matches the pressure difference, monitor it again until the pressure difference drops to 0, and then turn off the air pump, the second shut-off valve, and the third shut-off valve.

[0069] Preferably, the data acquisition unit further includes a second pressure sensor and a third pressure sensor.

[0070] The second pressure sensor is located on the inner wall of the pipe at the air exhaust outlet of the fuel cell stack, and is used to obtain the air pressure data of the exhaust air exiting the stack at the current moment.

[0071] The third pressure sensor is located on the inner wall of the pipe at the hydrogen exhaust outlet of the fuel cell stack, and is used to obtain the pressure data of the hydrogen exhaust gas exiting the stack at the current moment.

[0072] Preferably, the display module's screen also displays the pressure difference between the data collected by the second and third pressure sensors after the fuel cell is shut down, serving as the negative pressure on both sides of the hydrogen and air stack.

[0073] Preferably, the data processing and control unit further executes the following program:

[0074] S5. Obtain the pressure of the exhaust air and exhaust hydrogen at the current moment;

[0075] S6. Based on the changes in the pressure of the exhaust air and the exhaust hydrogen during the set time period, identify whether there is a possible leak on the hydrogen side or the air side of the fuel cell stack; if the identification result is that there is a leak on the hydrogen side of the fuel cell stack, issue an alarm message; if the identification result is that there is a leak on the air side of the fuel cell stack, open the second shut-off valve and the third shut-off valve, start the air pump, and adjust the air pump speed so that the pressure of the exhaust air is always equal to the pressure of the exhaust hydrogen until the fuel cell engine starts.

[0076] Preferably, the data acquisition unit further includes an ambient temperature sensor located outside the fuel cell stack. The ambient temperature sensor is used to acquire the ambient temperature of the on-board fuel cell engine.

[0077] Furthermore, the display module's screen also displays the current ambient temperature collected by the aforementioned ambient temperature sensor. Through this temperature, designers and users can determine whether thermal expansion and contraction may occur within the fuel cell stack, resulting in a negative temperature difference.

[0078] Preferably, the data processing and control unit further executes the following program:

[0079] S7. Obtain the ambient temperature collected by the ambient temperature sensor and identify whether there is a possibility of thermal expansion and contraction inside the fuel cell stack; if so, proceed to step S8; otherwise, return to step S2 to periodically monitor whether negative pressure is formed on both sides of the hydrogen-air mixture inside the fuel cell stack.

[0080] S8. Identify whether the pressure of the exhaust air from the reactor is equal to the pressure of the exhaust hydrogen from the reactor. If they are not equal, immediately open the second and third shut-off valves and start the air pump. Adjust the air pump speed to make the pressure of the exhaust air from the reactor equal to the pressure of the exhaust hydrogen from the reactor. Then close the air pump and the second and third shut-off valves and identify again whether there is a possibility of thermal expansion and contraction.

[0081] Preferably, the data acquisition unit further includes a hydrogen concentration sensor and an oxygen concentration sensor.

[0082] A hydrogen concentration sensor is installed on the inner wall of the pipe at the hydrogen inlet of the fuel cell stack to obtain the concentration of hydrogen entering the stack.

[0083] An oxygen concentration sensor is installed on the inner wall of the duct at the air inlet of the fuel cell stack to obtain the oxygen concentration in the incoming air.

[0084] Preferably, the fuel cell engine further includes a fifth shut-off valve; wherein the hydrogen inlet of the fuel cell stack is also connected to the outlet of the gas storage tank via the fifth shut-off valve.

[0085] Preferably, the controller is further configured to, upon receiving a shutdown command from the fuel cell, control the second and fifth shut-off valves to open until the data collected by the hydrogen concentration sensor and oxygen concentration sensor are both lower than the set values, and then control the first to fifth shut-off valves to close.

[0086] Compared with the prior art, the fuel cell engine provided in this embodiment has the following beneficial effects:

[0087] 1. A structure and procedure for mitigating negative pressure have been added, namely a gas storage tank containing nitrogen or inert gas, a second shut-off valve, a third shut-off valve, and an air pump. Automatic pressure replenishment is achieved by filling the tank with gas to prevent negative pressure from forming during long-term storage of the vehicle.

[0088] 2. This avoids failure due to large hydrogen-air pressure difference during restart.

[0089] 3. It does not affect customer perception and improves user-friendliness.

[0090] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, and are not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical applications, or improvements to the prior art of the embodiments, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A fuel cell engine, characterized in that, It includes an electric stack, a gas storage tank containing non-reactive gases, a gas pump, an air compressor, first to fourth shut-off valves, and a controller; The air inlet of the fuel cell stack is connected to the output end of the air compressor via the first shut-off valve, and to the air outlet of the air storage tank via the second shut-off valve. Its air outlet is connected to the air pump via the third shut-off valve, and to the vehicle exhaust pipe via the fourth shut-off valve. The controller is used to receive a fuel cell shutdown command and control the first to fourth shut-off valves to close; and to periodically monitor whether a negative pressure is formed on both sides of the hydrogen-air mixture in the fuel cell stack. Once formed, it controls the second and third shut-off valves to open, and the gas pump to operate at a speed matching the negative pressure. The controller monitors again until the negative pressure disappears, and then shuts off the gas pump and the second and third shut-off valves. The controller further includes: The data acquisition unit obtains the air pressure at the air inlet of the fuel cell stack and sends it to the data processing and control unit; The data processing and control unit is used to receive a fuel cell shutdown command and control all four shut-off valves to close; and to periodically monitor whether the pressure difference between the air pressure at the air inlet of the fuel cell stack and the target air pressure exceeds a set threshold range. If it does, the unit opens the second and third shut-off valves and controls the air pump to operate at a speed matching the pressure difference until the absolute value of the pressure difference drops below the set value, and then shuts off the air pump and the second and third shut-off valves. The data acquisition unit further includes: The first pressure sensor is located on the inner wall of the pipe at the air inlet of the fuel cell stack and is used to obtain the air pressure at the air inlet of the fuel cell stack at the current moment. The data processing and control unit executes the following program: Upon receiving the fuel cell shutdown command, control all four shut-off valves (first to fourth) to close. Regularly monitor whether the pressure difference between the air pressure at the air inlet of the fuel cell stack and the target air pressure exceeds the set threshold range. If it does, proceed to the next step; otherwise, end the current monitoring cycle. The second and third shut-off valves are opened simultaneously, and the air pump is started. Adjust the air pump to operate at a speed that matches the pressure difference, monitor it again, until the pressure difference drops to 0, then turn off the air pump, the second shut-off valve, and the third shut-off valve. The data acquisition unit also includes: The second pressure sensor is located on the inner wall of the pipe at the air exhaust outlet of the fuel cell stack, and is used to obtain the air pressure of the exhaust air exiting the stack at the current moment. The third pressure sensor is located on the inner wall of the pipe at the hydrogen tail gas outlet of the fuel cell stack, and is used to obtain the pressure of the hydrogen tail gas exiting the stack at the current moment. The data processing and control unit also executes the following program: Obtain the pressure of the exhaust air and exhaust hydrogen at the current moment, respectively; Based on the changes in the pressure of the exhaust air and the exhaust hydrogen during the set time period, the system identifies whether there may be leaks on the hydrogen side or the air side of the fuel cell stack. If the identification result indicates a leak on the hydrogen side of the fuel cell stack, an alarm message is issued. If the identification result indicates a leak on the air side of the fuel cell stack, the second and third shut-off valves are opened, the air pump is started, and the air pump speed is adjusted so that the pressure of the exhaust air is always equal to the pressure of the exhaust hydrogen until the fuel cell engine starts.

2. The fuel cell engine according to claim 1, characterized in that, The gas storage tank contains at least one of nitrogen or an inert gas.

3. The fuel cell engine according to claim 1, characterized in that, The data acquisition unit also includes an ambient temperature sensor located outside the fuel cell stack; and... The data processing and control unit also executes the following program: The ambient temperature is collected by the ambient temperature sensor to identify whether there is a possibility of thermal expansion and contraction inside the fuel cell stack. If so, proceed to the next step; otherwise, monitor periodically whether a negative pressure is formed on both sides of the hydrogen-air interface inside the fuel cell stack. Identify whether the pressure of the exhaust air from the reactor is equal to the pressure of the exhaust hydrogen from the reactor. If they are not equal, immediately open the second and third shut-off valves and start the air pump. Adjust the air pump speed to make the pressure of the exhaust air from the reactor equal to the pressure of the exhaust hydrogen from the reactor. Then close the air pump and the second and third shut-off valves and re-identify whether there is any possibility of thermal expansion and contraction.

4. The fuel cell engine according to claim 1, characterized in that, The data acquisition unit also includes: A hydrogen concentration sensor is installed on the inner wall of the pipe at the hydrogen inlet of the fuel cell stack to obtain the concentration of hydrogen entering the stack. An oxygen concentration sensor is installed on the inner wall of the duct at the air inlet of the fuel cell stack to obtain the oxygen concentration in the incoming air.

5. The fuel cell engine according to claim 4, characterized in that, It also includes a fifth shut-off valve; among which, The hydrogen inlet of the fuel cell stack is also connected to the outlet of the gas storage tank via a fifth shut-off valve. The controller is also used to control the second and fifth shut-off valves to open after receiving a shutdown command from the fuel cell, until the data collected by the hydrogen concentration sensor and the oxygen concentration sensor are both lower than the set value, and then control the first to fifth shut-off valves to close.

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