Hydrogen engine hydrogen concentration control system and method

Abstract

The present application relates to the field of automobile manufacturing, in particular to a hydrogen engine hydrogen concentration control system and method, the system comprises a hydrogen flow sensor, an air inlet pressure sensor, an air inlet flow sensor, a crankcase pressure sensor, a gas supplement valve and an ECU. The method steps include: the ECU real-time monitors the hydrogen engine air inlet flow and hydrogen injection flow, calculates the limit ratio of hydrogen content in exhaust gas based on the ratio of hydrogen injection amount and air inlet amount per cycle; based on the amount of blow-by gas and the hydrogen content ratio in the blow-by gas, the total amount of hydrogen is obtained, and the gas supplement valve opening is accurately controlled; the pressurized air is introduced from the low part of the crankcase to scavenge and dilute the hydrogen gas, and is discharged through the air inlet at the highest point of the cylinder cover, forming efficient control. The present application can realize accurate and rapid control of the hydrogen concentration in the hydrogen engine crankcase, effectively avoid the explosion risk caused by hydrogen accumulation, and balance the crankcase pressure stability and oil consumption control, thereby improving the safety of the hydrogen engine.

Description

Technical Field

[0001] This invention relates to the field of automobile manufacturing, and more specifically to a hydrogen concentration control system and method for a hydrogen engine. Background Technology

[0002] Traditional engines primarily generate mechanical energy through the combustion of fossil fuels such as diesel and gasoline. Since these fuels are mainly composed of hydrocarbons, their combustion products are primarily carbon dioxide and water. Therefore, in traditional engines, the crankcase mainly consists of engine combustion exhaust gases and engine oil. The crankcase ventilation system in traditional engines primarily functions to separate oil and gas and control crankcase pressure. However, in hydrogen engines, a small amount of unburned hydrogen gas can enter the crankcase ventilation system through the gaps in the piston rings. Traditional crankcase ventilation systems cannot effectively reduce or remove this hydrogen concentration. Furthermore, due to the low density of hydrogen, it tends to accumulate in higher areas of the crankcase, forming hydrogen-rich zones. If the hydrogen concentration exceeds a certain range, it poses a significant risk of explosion.

[0003] In existing engine technologies, the following technical means are mainly used to mitigate the phenomenon of excessive hydrogen concentration in the crankcase's enclosed space: Utilizing the traditional engine's crankcase ventilation system, but this cannot avoid the risk of hydrogen accumulation in the crankcase; Adding an electrically driven forced extraction of gas from the crankcase ventilation system to achieve forced removal of exhaust gases. However, this solution requires a large-flow forced extraction of gas from the crankcase to control the hydrogen concentration, which can easily lead to uncontrolled pressure in the crankcase and increased oil leakage through the crankcase ventilation system. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a hydrogen concentration control system and method for a hydrogen engine. This method combines the crankcase structural design, crankcase ventilation strategy, and hydrogen concentration control method of a hydrogen engine to achieve effective control of the hydrogen concentration within the crankcase space. This is of great significance for the development and industrial application of hydrogen engines. The specific technical solution is as follows: A hydrogen concentration control system for a hydrogen engine, comprising an air filter, a turbocharger, a cylinder head cover, a crankcase pressure sensor, a crankcase ventilation pipe a, a high-efficiency oil-gas separator, a cylinder head, a cylinder block, a hydrogen injector, an oil pan, an oil return pipe, a piston assembly, unburned hydrogen, a make-up air pipe, a make-up air valve, an internal ventilation channel, a crankcase ventilation pipe b, a hydrogen engine control unit (ECU), an intake air pressure sensor, an intake air flow sensor, and a hydrogen flow sensor.

[0005] The cylinder block, piston assembly, and cylinder head together form the combustion chamber, with the hydrogen injector supported on the cylinder head. A cylinder head cover is installed above the cylinder head. A crankcase pressure sensor and crankcase ventilation pipe a are installed on top of the cylinder head cover. Crankcase ventilation pipe a is connected to a high-efficiency oil-gas separator, and the separated gas is connected to the front of the turbocharger via crankcase ventilation pipe b. The separated engine oil flows back to the oil pan located at the bottom of the cylinder block via a return oil pipe. The turbocharger is located behind the air filter to pressurize the fresh air after it passes through the air filter, providing pressure drive for the air injection in the crankcase; an intake pressure sensor is installed on the pipeline after the turbocharger, one pipeline enters the cylinder head through the intake flow sensor, and another pipeline enters the oil pan through the air injection pipe and air injection valve; an internal ventilation channel is provided between the oil pan and the cylinder head cover. The hydrogen engine control unit (ECU) is electrically connected to a crankcase pressure sensor, intake air pressure sensor, intake air flow sensor, hydrogen flow sensor, and a make-up air valve. Based on the hydrogen flow rate and intake air volume, the ECU calculates the hydrogen content limit in the blow-by gas from the piston rings and, combined with the engine design blow-by map, calculates the total amount of hydrogen in the blow-by gas. This provides opening commands to the make-up air valve, controlling its opening size. After pressurization, fresh air enters the crankcase through the make-up air pipe, achieving a "scavenging" effect on the unburned hydrogen. This dilutes the unburned hydrogen and carries it through the built-in ventilation channels to the highest point of the cylinder head cover. Finally, it exits the crankcase sealed space via crankcase ventilation pipes a and b, effectively controlling the residual hydrogen concentration in the crankcase.

[0006] Furthermore, the cylinder head cover is roof-shaped, which allows residual hydrogen in the crankcase to smoothly accumulate and flow out at the highest point of the roof; and a primary oil-gas separator is designed inside the cylinder head cover to separate and filter the oil and gas. Furthermore, the crankcase ventilation pipe b is positioned close to the turbocharger at the connection point before the turbocharger to provide sufficient negative pressure to drive the gas flow in the crankcase. This invention provides a control method based on the aforementioned hydrogen concentration control system for a hydrogen engine, specifically including the following steps: Step 1: After the engine starts, the ECU receives the hydrogen flow rate collected by the hydrogen flow sensor and the intake air volume signal collected by the intake air flow sensor in real time, and calculates the ratio of hydrogen flow rate to intake air volume. Step 2: When the ratio of hydrogen flow rate to intake air volume is lower than the first preset threshold, it is determined to be a normal state, the ECU does not perform the air replenishment operation, and continues to monitor; Step 3: When the ratio of hydrogen flow rate to intake air volume is detected to be greater than the first preset threshold, the ECU further calculates the total amount of hydrogen gas leaking out through the piston rings in conjunction with the preset blow-by volume Map. Step 4: Acquire the pressure signals collected by the intake pressure sensor and crankcase pressure sensor, and calculate the pressure difference between the intake pressure and the crankcase pressure. Step 5: The ECU queries the preset gas filling valve opening control map Map based on the current amount of hydrogen gas leaking out and the pressure difference value to determine the target opening value; Step 6: The ECU sends a control command to the air supply valve to open it to the target opening value, so as to allow the pressurized fresh air to enter the lower area of ​​the crankcase through the air supply pipe. Step 7: The incoming fresh air scavenges and dilutes the residual hydrogen at the bottom and inside of the crankcase, forcing the mixture containing the diluted hydrogen to flow upwards. It then passes through the built-in ventilation channel, the air intake at the top of the cylinder head cover, the crankcase ventilation pipe, and the high-efficiency oil-gas separator, and is finally introduced into the turbocharger's intake pipeline to participate in combustion, forming a closed-loop control.

[0007] Furthermore, when the crankcase pressure exceeds the threshold range after the supplemental gas is detected, the ECU triggers an alarm and adjusts the hydrogen injection quantity of the hydrogen engine to regulate the operating conditions and limit the engine torque output.

[0008] This invention achieves precise and rapid control of hydrogen concentration in the crankcase of a hydrogen engine through a combination of structural design and control strategies, effectively avoiding the explosion risk caused by hydrogen accumulation. At the same time, it also ensures stable crankcase pressure and oil consumption control, significantly improving the safety of the hydrogen engine.

[0009] This invention monitors the hydrogen injection and intake air volumes, and, combined with the engine design's surge map, calculates the hydrogen content that leaks into the crankcase space via the piston rings. By combining the intake pressure and crankcase pressure difference, it ensures the make-up air valve is within an effective and appropriate opening range. This guarantees effective "scavenging" and dilution of residual hydrogen while preventing crankcase pressure runaway and abnormal oil consumption caused by excessive crankcase ventilation. This solution ensures the hydrogen concentration in the sealed space remains effectively within a controllable range, providing essential technical support for the safe operation of hydrogen engines. Furthermore, this solution offers rapid adjustment response, providing significant guidance for improving the safe and reliable production and operation of hydrogen internal combustion engines. Attached Figure Description

[0010] Figure 1 A schematic diagram of the structure of the system of this invention; Figure 2 A flowchart illustrating the control method of this invention.

[0011] Figure label: 1 is air filter, 2 is turbocharger, 3 is cylinder head cover, 4 is crankcase pressure sensor, 5 is crankcase ventilation pipe a, 6 is high-efficiency oil-gas separator, 7 is cylinder head, 8 is cylinder block, 9 is hydrogen injector, 10 is oil pan, 11 is oil return pipe, 12 is piston assembly, 13 is unburned hydrogen, 14 is air injection pipe, 15 is air injection valve, 16 is built-in ventilation channel, 17 is crankcase ventilation pipe b, 18 is hydrogen engine control unit (ECU), 19 is intake pressure sensor, 20 is intake air flow sensor, and 21 is hydrogen flow sensor. Detailed Implementation

[0012] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 are within the scope of protection of the present invention.

[0013] like Figure 1 As shown, the present invention comprises an air filter 1, a turbocharger 2, a cylinder head cover 3, a crankcase pressure sensor 4, a crankcase ventilation pipe a5, a high-efficiency oil-gas separator 6, a cylinder head 7, a cylinder block 8, a hydrogen injector 9, an oil pan 10, a return oil pipe 11, a piston assembly 12, unburned hydrogen 13, a make-up air pipe 14, a make-up air valve 15, an internal ventilation channel 16, a crankcase ventilation pipe b17, a hydrogen engine control unit (ECU) 18, an intake pressure sensor 19, an intake flow sensor 20, and a hydrogen flow sensor 21.

[0014] The turbocharger 2 pressurizes the fresh air after passing through the air filter 1, providing pressure drive for the air supply in the crankcase; the cylinder head cover 3, compared with the traditional cylinder head cover design, needs to be designed as a roof shape to allow residual hydrogen in the crankcase to smoothly accumulate and flow out at the highest point of the roof; at the same time, a primary oil-gas separator is designed inside the cylinder head cover to achieve the first separation and filtration of oil and gas.

[0015] A crankcase pressure sensor, positioned at the highest point of the cylinder head cover, enables real-time monitoring of the crankcase pressure, providing accurate data support for the ECU to execute crankcase air injection control strategies. The crankcase ventilation pipe a5, with its connection point to the cylinder head cover at the highest point, aims to quickly and efficiently expel crankcase ventilation gases (including residual hydrogen) from the crankcase. The high-efficiency oil-gas separator 6, to control the concentration of residual hydrogen in the crankcase, requires the introduction of a significant amount of fresh air to dilute the residual hydrogen concentration. To avoid the impact of large-flow gas on the amount of oil leaking into the crankcase ventilation, the hydrogen engine adds a high-efficiency oil-gas separator 6 compared to traditional engines, which achieves secondary filtration of the engine oil in the crankcase ventilation. The filtered engine oil flows back to the oil pan 10 along the oil return pipe 11. The filtered crankcase ventilation gas flows along the crankcase ventilation pipe b17 and finally reaches the front of the turbocharger. The crankcase ventilation pipe b17 is arranged as close as possible to the turbocharger at the connection point before the turbocharger 2 to provide sufficient negative pressure to drive the flow of gas in the crankcase.

[0016] Cylinder head 7 provides mounting support for hydrogen injector 9; cylinder block 8, together with piston assembly 12 and cylinder head 7, forms the combustion chamber, providing the necessary conditions for combustion and power generation in the hydrogen engine; unburned hydrogen 13, during the operation of the hydrogen engine, a small amount of unburned hydrogen enters the crankcase through the tiny gap between piston ring assembly 12 and cylinder bore.

[0017] Based on hydrogen flow rate, intake air volume information, and engine design spurt map information, the engine control unit (ECU) 18 calculates the total amount of hydrogen that leaks into the crankcase space via the piston rings; it then provides an opening command to the air replenishment valve 15; the air replenishment valve 15 controls the opening size according to the ECU control command, and the pressurized fresh air enters the crankcase through the air replenishment pipe 14; this achieves the "scavenging" effect of fresh air on unburned hydrogen 13, diluting the unburned hydrogen and carrying it to the high point of the cylinder head cover through the built-in ventilation channel 16, and finally carrying it out of the crankcase sealed space through the crankcase ventilation pipe a and ventilation pipe b, thus effectively controlling the concentration of residual hydrogen in the crankcase.

[0018] Specific control method: After the engine starts, the hydrogen flow sensor and the intake air flow sensor send data to the control unit. The control unit calculates the hydrogen concentration level of the in-cylinder mixture. When the hydrogen concentration level is ≤ a1, the engine control unit judges it as a normal state and does not need to take action, but continues to monitor. When the hydrogen concentration level is > a1, the control unit calculates the total amount of hydrogen blow-by through the piston rings in conjunction with the designed blow-by volume Map. The engine control unit (ECU) further obtains the intake pressure from the intake pressure sensor 19 and the crankcase pressure from the crankcase pressure sensor 4, and obtains the pressure difference. Finally, based on the pressure difference and the total amount of hydrogen blow-by, the amount of fresh air to be added to the crankcase sealed space is calculated. The opening of the air injection valve is determined based on the demand to provide fresh boost pressure to the crankcase. Fresh air is delivered to the lower part of the engine (oil pan or lower part of the cylinder block) through the air injection pipe 14 to achieve "scavenging" of unburned hydrogen 13. At the same time, due to the addition of fresh air, the concentration of residual hydrogen in the crankcase sealed space will be quickly diluted.

[0019] The diluted crankcase ventilation gas is rapidly introduced into the intake air through the built-in ventilation channel 16, cylinder head cover 3, crankcase ventilation pipe a5, high-efficiency oil-gas separator 6, and crankcase ventilation pipe b17, and finally re-enters the cylinder to participate in combustion, achieving closed-loop control of unburned hydrogen.

[0020] When an engine malfunctions and the crankcase pressure exceeds the design threshold at the fresh air intake port, the engine will trigger operating condition adjustment requirements, reducing the amount of hydrogen injected and implementing limit torque protection.

[0021] Meanwhile, in order to reduce the leakage of unburned hydrogen during combustion, the piston assembly (with piston rings) needs to be specially designed to improve the compliance of the piston rings and appropriately reduce the piston ring gap, thereby achieving less leakage of unburned hydrogen.

[0022] It is particularly important to note that, in this invention, considering various factors such as layout, an external air supply channel is used to directly supply fresh air to the oil pan or the lower part of the cylinder block for "scavenging" dilution; alternatively, the air supply can be directly delivered to the cylinder head cover, and fresh air can be delivered from top to bottom to the oil pan or the lower part of the cylinder block for "scavenging" dilution through air supply channels set on the cylinder head or cylinder block.

[0023] The preferred embodiments of this patent have been described in detail above. However, this patent is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this patent.

Claims

1. A hydrogen concentration control system for a hydrogen engine, characterized in that: The system includes an air filter, turbocharger, cylinder head cover, crankcase pressure sensor, crankcase ventilation pipe a, high-efficiency oil-gas separator, cylinder head, cylinder block, hydrogen injector, oil pan, oil return pipe, piston assembly, unburned hydrogen, air injection pipe, air injection valve, built-in ventilation passage, crankcase ventilation pipe b, hydrogen engine control unit (ECU), intake pressure sensor, intake flow sensor, and hydrogen flow sensor. The cylinder block, piston assembly, and cylinder head together form the combustion chamber, and the hydrogen injector is supported on the cylinder head. A cylinder head cover is installed above the cylinder head. A crankcase pressure sensor and crankcase ventilation pipe a are installed on the top of the cylinder head cover. The crankcase ventilation pipe a is connected to a high-efficiency oil-gas separator, and the separated gas is connected to the front of the turbocharger via crankcase ventilation pipe b. The separated engine oil flows back to the oil pan at the bottom of the cylinder block via the return oil pipe. The turbocharger is located behind the air filter to pressurize the fresh air after it passes through the air filter, providing pressure drive for the air injection in the crankcase; an intake pressure sensor is installed on the pipeline after the turbocharger, one pipeline enters the cylinder head through the intake flow sensor, and another pipeline enters the oil pan through the air injection pipe and air injection valve; an internal ventilation channel is provided between the oil pan and the cylinder head cover. The hydrogen engine control unit (ECU) is electrically connected to the crankcase pressure sensor, intake pressure sensor, intake flow sensor, hydrogen flow sensor, and make-up valve. The ECU calculates the limit value of hydrogen content in the blow-by gas of the piston rings based on the hydrogen flow and intake volume, and calculates the total amount of hydrogen in the blow-by gas in conjunction with the engine design blow-by map, and provides opening commands to the make-up valve to control the opening size of the make-up valve.

2. The hydrogen concentration control system for a hydrogen engine according to claim 1, characterized in that: The cylinder head cover is roof-shaped, which allows residual hydrogen in the crankcase to smoothly accumulate and flow out at the highest point of the roof; and a primary oil-gas separator is designed inside the cylinder head cover to separate and filter the oil and gas.

3. The hydrogen concentration control system for a hydrogen engine according to claim 1, characterized in that: The crankcase ventilation pipe b is positioned close to the turbocharger at the connection point before the turbocharger to provide sufficient negative pressure to drive the gas flow in the crankcase.

4. The control method for the hydrogen concentration control system of a hydrogen engine according to any one of claims 1-3, characterized in that: Specifically, the steps include the following: Step 1: After the engine starts, the ECU receives the hydrogen flow rate collected by the hydrogen flow sensor and the intake air volume signal collected by the intake air flow sensor in real time, and calculates the ratio of hydrogen flow rate to intake air volume. Step 2: When the ratio of hydrogen flow rate to intake air volume is lower than the first preset threshold, it is determined to be a normal state, the ECU does not perform the air replenishment operation, and continues to monitor; Step 3: When the ratio of hydrogen flow rate to intake air volume is detected to be greater than the first preset threshold, the ECU further calculates the total amount of hydrogen gas leaking out through the piston rings in conjunction with the preset blow-by map. Step 4: Acquire the pressure signals collected by the intake pressure sensor and crankcase pressure sensor, and calculate the pressure difference between the intake pressure and the crankcase pressure. Step 5: The ECU queries the preset gas filling valve opening control map Map based on the current amount of hydrogen gas leaking out and the pressure difference value to determine the target opening value; Step 6: The ECU sends a control command to the air supply valve to open it to the target opening value, so as to allow the pressurized fresh air to enter the lower area of ​​the crankcase through the air supply pipe. Step 7: The incoming fresh air scavenges and dilutes the residual hydrogen at the bottom and inside of the crankcase, forcing the mixture containing the diluted hydrogen to flow upwards. It then passes through the built-in ventilation channel, the air intake at the top of the cylinder head cover, the crankcase ventilation pipe, and the high-efficiency oil-gas separator, and is finally introduced into the turbocharger's intake pipeline to participate in combustion, forming a closed-loop control.

5. The control method according to claim 4, characterized in that: When the crankcase pressure exceeds the preset range after the injection of gas, the ECU triggers a hydrogen engine operation correction command to adjust the amount of hydrogen injected under operating conditions and limit the engine torque output.

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