Control method and system for self-adaptively adjusting hydrogen combustion

Abstract

The invention discloses a control method and system for self-adaptively adjusting hydrogen combustion, belongs to the technical field of internal combustion engine control, and solves the technical problem of abnormal combustion phenomena of preignition and knocking. The method comprises the steps that the exhaust valve is controlled to be closed in advance, the negative valve overlap angle is achieved, part of waste gas is internally recirculated, water spraying of the air inlet channel is controlled in a coupled mode, and therefore the too high hydrogen combustion rate is restrained, the ignition delay period is prolonged, and the knocking and preignition probability is reduced. Specifically, the engine load is obtained in real time; when the load of the engine is larger than or equal to 10% and smaller than 40%, the working condition is a medium and small load working condition, the ignition delay period is prolonged only by controlling an exhaust valve to close intercepted waste gas in advance, and meanwhile the hydrogen preignition phenomenon is relieved; when the load of the engine is larger than 40% and smaller than or equal to 100%, the working condition is a large-load working condition, on the basis that an exhaust valve is controlled to be closed in advance, the temperature in the cylinders of the internal combustion engine is reduced by controlling water sprayed into each air cylinder, and therefore the conditions of preignition and detonation of the internal combustion engine are eliminated.

Description

Technical Field

[0001] This invention relates to the field of internal combustion engine control technology, and more specifically, to a control method and system for adaptively adjusting hydrogen combustion. Background Technology

[0002] Hydrogen, as an ideal zero-carbon emission fuel, produces water as its combustion product, giving it enormous potential as a core power source for future clean energy vehicles. This is significant for reducing carbon emissions in the transportation sector and contributing to the goal of carbon neutrality. However, hydrogen's high reactivity and wide flammability limit make it extremely easy and fast-burning, inducing abnormal combustion phenomena such as pre-ignition and knocking. It can also lead to problems like intake backfire and high NOx emissions, limiting the potential for power and efficiency improvements in hydrogen engines. Therefore, reconciling the technical contradiction between suppressing abnormal hydrogen combustion and improving engine performance has become a core key to promoting the technological iteration and industrial application of hydrogen fuel cell engines.

[0003] Therefore, there is an urgent need for a method that can regulate the excessively fast hydrogen combustion rate, reduce abnormal combustion phenomena such as pre-ignition and knocking in hydrogen engines, reduce nitrogen oxide emissions, expand their operating range, and further improve the performance of hydrogen engines. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the above-mentioned shortcomings of the prior art. The objective of the present invention is to provide an adaptive control method for adjusting hydrogen combustion.

[0005] The second objective of this invention is to provide an adaptive control system for adjusting hydrogen combustion.

[0006] To achieve the first objective mentioned above, this invention provides an adaptive control method for hydrogen combustion. By controlling the exhaust valve to close early, a negative valve overlap angle is achieved, allowing some of the exhaust gas to recirculate internally. This is coupled with the control of water injection in the intake manifold, thereby suppressing excessively fast hydrogen combustion rate, extending the ignition delay period, and reducing the probability of knocking and pre-ignition.

[0007] As a further improvement, the following steps are included: Step 1. Obtain engine load in real time; Step 2. When the engine load is greater than or equal to 10% and less than 40%, it is a medium-to-low load condition. The combustion delay period is extended by controlling the exhaust valve to close in advance to trap the exhaust gas, so that the hydrogen fuel and air are mixed more fully and the hydrogen pre-ignition phenomenon is reduced. Step 3. When the engine load is greater than 40% and less than or equal to 100%, it is a high-load operating condition. Based on controlling the early closing of the exhaust valve, the temperature inside the internal combustion engine is reduced by controlling the water injected into each cylinder, thereby eliminating the pre-ignition and knocking of the internal combustion engine.

[0008] Furthermore, under heavy load conditions, the knocking situation inside the cylinder is detected in real time; If knocking occurs in the cylinder, increase the water injection volume until the knocking is eliminated, and maintain the current water injection volume under this condition; If the operating conditions change, continue with steps 1 through 3.

[0009] Furthermore, controlling the early closing of the exhaust valve specifically means that the exhaust valve closes before the top dead center by an angle ε, where ε = 4~5°CA.

[0010] Furthermore, the water injection pressure MAP and water injection pulse width MAP corresponding to the engine load are pre-calibrated. The water injection pressure and water injection pulse width MAP are queried according to the actual engine load to control the water injection pressure and water injection pulse width, so as to control the water injected into each cylinder.

[0011] To achieve the second objective mentioned above, the present invention provides an adaptive control system for adjusting hydrogen combustion, comprising a water injector, a hydrogen nozzle, an ECU, a knock sensor, a spark plug, a water tank, and a high-pressure water pump. The water injector is installed on the intake manifold, and the ECU is electrically connected to the water injector, the hydrogen nozzle, the knock sensor, the spark plug, the water tank, and the high-pressure water pump. The ECU acquires the engine load in real time, detects the knocking situation in the cylinder in real time through the knock sensor, and controls the exhaust valve to close early and the water injector to work according to the adaptive hydrogen combustion control method described above.

[0012] Beneficial effects Compared with the prior art, the advantages of this invention are as follows: This invention matches an exhaust valve early closing phase system to an in-cylinder hydrogen-injected engine and adds a water injection system to the intake manifold. When the hydrogen engine is under low to medium load conditions, the exhaust valve early closing strategy is adopted, while under high load conditions, the exhaust valve early closing coupled with the intake manifold water injection strategy is adopted. The entire operating strategy can effectively broaden the combustion range of the hydrogen engine, suppress abnormal combustion phenomena such as hydrogen pre-ignition and knocking, and improve the overall performance of the hydrogen engine. Attached Figure Description

[0013] Figure 1 Phase diagram for early closure of exhaust valves; Figure 2 This is a schematic diagram of the intake manifold water spray system. Figure 3 This is the logic diagram for the water spray control in the air intake.

[0014] Among them: 1-water injector, 2-hydrogen nozzle, 3-ECU, 4-knock sensor, 5-spark plug, 6-water tank, 7-high pressure water pump. Detailed Implementation

[0015] The present invention will be further described below with reference to specific embodiments shown in the accompanying drawings.

[0016] See Figures 1-3 An adaptive control method for hydrogen combustion is proposed. By controlling the exhaust valve to close early and achieving a negative valve overlap angle, some exhaust gas is recirculated internally. This is coupled with the control of water injection in the intake manifold, thereby suppressing excessively fast hydrogen combustion rate, prolonging the ignition delay period, and reducing the probability of knocking and pre-ignition.

[0017] Early exhaust valve closing achieves internal exhaust gas recirculation by utilizing changes in the intake and exhaust valve timing to increase the amount of residual exhaust gas in the engine cylinders. The inert gas components in the exhaust gas enhance the quenching reaction, prolonging the auto-ignition time of the final mixture, thereby reducing the maximum combustion temperature and NOx emissions. However, this method struggles to achieve precise EGR rate control under high loads, where the demand for in-cylinder exhaust gas increases significantly. In such conditions, the EGR rate achieved through early exhaust valve closing cannot meet the requirements of high-load operation, and the high temperature of the retained exhaust gas in the cylinder increases the likelihood of pre-ignition and knocking. Therefore, it is necessary to combine this method with an intake manifold water injection system to suppress excessively rapid hydrogen combustion, prolong the ignition delay period, and reduce the probability of knocking and pre-ignition.

[0018] Specifically, the following steps are included: Step 1. Obtain engine load in real time; Step 2. When the engine load is greater than or equal to 10% and less than 40%, it is a medium-to-low load condition. The ignition delay period is extended solely by controlling the early closure of the exhaust valve to trap the exhaust gas, thus avoiding lubrication and wear problems caused by water accumulation in the intake manifold. At this time, the ignition delay period is extended solely by relying on the exhaust gas trapped by the early closure of the exhaust valve, allowing for more complete mixing of hydrogen fuel and air, while also mitigating phenomena such as hydrogen pre-ignition. like Figure 1 As shown in the diagram, the exhaust valve closes early, achieving a negative valve overlap angle and trapping exhaust gases inside the cylinder. Specifically, the exhaust valve closes ε degrees before top dead center (approximately 4-5°CA earlier than the original exhaust valve closing angle), trapping some exhaust gases inside the cylinder to participate in the next working cycle, thus achieving internal EGR. Meanwhile, the intake valve is not yet open, and the valve overlap angle is negative (α-ε). Step 3. When the engine load is greater than 40% and less than or equal to 100%, it is a high-load operating condition. Based on controlling the early closing of the exhaust valve, the temperature inside the internal combustion engine is reduced by controlling the water injected into each cylinder, thereby eliminating the pre-ignition and knocking of the internal combustion engine.

[0019] Under heavy load conditions, the knocking situation in the cylinder is monitored in real time; if knocking occurs in the cylinder, the water injection volume is increased until the knocking is eliminated, and the current water injection volume is maintained unchanged under this condition; if the operating conditions change, steps 1 to 3 are continued.

[0020] Controlling the early closing of the exhaust valve specifically means that the exhaust valve closes before the top dead center by an angle ε, where ε = 4~5°CA.

[0021] The water injection pressure MAP and water injection pulse width MAP corresponding to the engine load are pre-calibrated. The water injection pressure and water injection pulse width MAP are queried according to the actual engine load to control the water injection pressure and water injection pulse width, so as to control the water injected into each cylinder.

[0022] An adaptive control system for adjusting hydrogen combustion, such as Figure 2 As shown, it includes a water injector 1, a hydrogen nozzle 2, an ECU 3, a knock sensor 4, a spark plug 5, a water tank 6, and a high-pressure water pump 7. The water injector 1 is installed on the intake manifold, and the hydrogen nozzle 2, knock sensor 4, and spark plug 5 are installed on the cylinder block. The ECU 3 is electrically connected to the water injector 1, hydrogen nozzle 2, knock sensor 4, spark plug 5, water tank 6, and high-pressure water pump 7.

[0023] ECU3 is connected to water injector 1 via a wire to adjust the injection timing and pulse width of the water nozzle. ECU3 is also connected to hydrogen injector 2 via a wire to adjust the injection timing and pulse width of the hydrogen nozzle. ECU3 is further connected to spark plug 5 via a wire to adjust the ignition timing and ignite the hydrogen. ECU3 receives signals from knock sensor 4.

[0024] ECU3 acquires engine load in real time, detects knocking in the cylinder in real time through knock sensor 4, and controls the exhaust valve to close early and the water injector 1 to work according to the above-mentioned adaptive adjustment hydrogen combustion control method.

[0025] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention, and these will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A method for adaptively adjusting hydrogen combustion control, characterized in that, By controlling the exhaust valve to close early and achieving a negative valve overlap angle, some exhaust gas can be recirculated internally. This, coupled with the control of water injection in the intake manifold, suppresses excessively fast hydrogen combustion rate, prolongs the ignition delay period, and reduces the probability of knocking and pre-ignition.

2. The adaptive control method for hydrogen combustion according to claim 1, characterized in that, Includes the following steps: Step 1. Obtain engine load in real time; Step 2. When the engine load is greater than or equal to 10% and less than 40%, it is a medium-to-low load condition. The combustion delay period is extended by controlling the exhaust valve to close in advance to trap the exhaust gas, so that the hydrogen fuel and air are mixed more fully and the hydrogen pre-ignition phenomenon is reduced. Step 3. When the engine load is greater than 40% and less than or equal to 100%, it is a high-load operating condition. Based on controlling the early closing of the exhaust valve, the temperature inside the internal combustion engine is reduced by controlling the water injected into each cylinder, thereby eliminating the pre-ignition and knocking of the internal combustion engine.

3. The adaptive control method for hydrogen combustion according to claim 2, characterized in that, Real-time monitoring of cylinder knocking under heavy load conditions; If knocking occurs in the cylinder, increase the water injection volume until the knocking is eliminated, and maintain the current water injection volume under this condition; If the operating conditions change, continue with steps 1 through 3.

4. The adaptive control method for hydrogen combustion according to claim 2, characterized in that, Controlling the early closing of the exhaust valve specifically means that the exhaust valve closes before the top dead center by an angle ε, where ε = 4~5°CA.

5. The adaptive control method for hydrogen combustion according to claim 2, characterized in that, The water injection pressure MAP and water injection pulse width MAP corresponding to the engine load are pre-calibrated. The water injection pressure and water injection pulse width MAP are queried according to the actual engine load to control the water injection pressure and water injection pulse width, so as to control the water injected into each cylinder.

6. A control system for adaptively adjusting hydrogen combustion, characterized in that, Includes a water injector (1), a hydrogen nozzle (2), an ECU (3), a knock sensor (4), a spark plug (5), a water tank (6), and a high-pressure water pump (7). The water injector (1) is installed on the intake manifold. The ECU (3) is electrically connected to the water injector (1), the hydrogen nozzle (2), the knock sensor (4), the spark plug (5), the water tank (6), and the high-pressure water pump (7). The ECU (3) acquires the engine load in real time, detects the knocking situation in the cylinder in real time through the knock sensor (4), and controls the exhaust valve to close in advance and the water injector (1) to work according to the adaptive adjustment hydrogen combustion control method according to any one of claims 1-5.

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