Pure ammonia engine idling speed stabilizing system and control method

Abstract

A kind of pure ammonia engine idle speed stabilizing system and control method, belong to the technical field of automobile engine.The idle speed stabilizing system includes engine body, air intake system, ammonia supply system, high-energy ignition device, accessory loading assembly and ECU;Ammonia supply system as the only fuel supply source of engine body, engine body is provided with high compression ratio shallow pot type combustion chamber, ECU according to engine speed and output torque control ammonia injection, high-energy ignition and accessory loading assembly, so that accessory load torque offsets positive output torque generated by pure ammonia combustion under idle speed condition.Ammonia supply system includes ammonia tank, PTC heater, buffer tank, ammonia filter, ammonia injection valve and mixer connected in sequence, and high-temperature gas output by air compressor can be used to heat ammonia through heat exchange device to reduce the risk of secondary liquefaction before injection.Control method by coordinating the adjustment of ammonia injection amount, ignition parameters and accessory load torque, and according to ammonia temperature, pressure and leakage concentration to perform heat exchange or cut-off control, realize pure ammonia engine idle speed stable operation and ammonia supply safety control.

Description

Technical Field

[0001] This invention belongs to the field of automotive engines, and specifically relates to a pure ammonia engine idle speed stabilization system and control method. Background Technology

[0002] Ammonia fuel contains no carbon and can be used as an alternative fuel for engines. Pure ammonia engines use ammonia as the sole fuel, eliminating the need for diesel ignition or hydrogen fuel for combustion, which simplifies multi-fuel storage and supply structures. However, ammonia fuel has characteristics such as a lower flame propagation speed, higher ignition energy requirement, and a narrower combustible range. Its ignition and combustion stability are weaker than traditional fuels such as gasoline and diesel, especially under engine idling and low-load conditions, where it is prone to problems such as ignition difficulties, slow combustion speed, significant combustion differences between cycles, and an increase in unburned ammonia.

[0003] When an engine is idling, the cylinder intake air volume and single-cycle fuel supply are relatively small, resulting in relatively low cylinder temperature, pressure, and turbulence intensity. The heat dissipation from the combustion chamber walls has a significant impact on the combustion process. For pure ammonia engines, reducing the ammonia injection quantity to lower the idle output torque may cause the ammonia-air mixture to approach the lean-burn or misfire boundary, leading to increased cycle fluctuations, unstable idle speed, or even engine stalling. Conversely, increasing the ammonia injection quantity to maintain stable combustion will result in a certain positive output torque at idle, easily causing the engine speed to exceed the target idle speed. Therefore, pure ammonia engines face a challenge in coordinating the fuel quantity required for stable combustion with the target idle output torque at idle.

[0004] Current engine idle speed control typically balances engine output torque with idle load by adjusting parameters such as throttle opening, fuel injection quantity, ignition advance angle, or injection timing. This control method is suitable for traditional fuel engines with a wide combustion stability range. However, when directly applied to pure ammonia engines, relying solely on ammonia injection quantity and ignition parameters to suppress idle speed increases can easily cause pure ammonia combustion to deviate from its stable operating range. While existing vehicles are equipped with accessory loads such as fans and air compressors, these typically start and stop independently based on cooling or vehicle airflow requirements, and are not yet coordinated with pure ammonia combustion output. Therefore, it is difficult to proactively generate corresponding load torque based on the engine's positive idle output torque.

[0005] Regarding ammonia supply, on-board ammonia fuel is typically stored in liquid form and requires heating, vaporization, pressure stabilization, filtration, and injection before mixing with air. The state of ammonia in the supply lines is easily affected by factors such as ambient temperature, line pressure, flow rate changes, and throttling cooling. When the ammonia temperature decreases or the pressure changes, the ammonia may liquefy again upstream of the injection valve, causing fluctuations in injection flow, inconsistent ammonia supply in different cycles, or uneven mixing of ammonia and air, further affecting the engine's idling combustion stability. Existing ammonia supply systems typically use independent electric heating devices to maintain the ammonia state, but a single heating method may have problems such as high energy consumption, insufficient localized heating, and difficulty in utilizing the vehicle's existing heat sources.

[0006] Furthermore, ammonia is irritating, and leaks in ammonia supply lines, connections, or injection valves can pose safety risks to vehicles, equipment, and personnel in the vicinity. While some existing ammonia supply systems are equipped with pressure monitoring or mechanical shut-off components, there is a lack of unified coordination between ammonia leak detection, supply cut-off, and engine control. This makes it difficult to quickly stop ammonia injection and bring the engine to a safe state when abnormal ammonia concentrations are detected.

[0007] Therefore, existing pure ammonia engines still need to solve the following technical problems: how to improve the combustion stability of pure ammonia under idling and low load conditions through combustion chamber structure, high-energy ignition, and ammonia supply parameter control; how to offset the positive output torque generated by the engine through controllable accessory load while ensuring stable combustion of pure ammonia; how to maintain the stability of ammonia temperature and pressure upstream of the ammonia injection valve and reduce the risk of secondary liquefaction; and how to coordinate and control ammonia supply, ignition control, accessory loading, status feedback, and leakage protection. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a pure ammonia engine idling speed stabilization system and control method, which coordinates and adjusts the ammonia injection quantity, ignition parameters and accessory load torque, and performs heat exchange or cut-off control according to the ammonia temperature, pressure and leakage concentration, so as to realize the stable idling speed operation and safe ammonia supply control of the pure ammonia engine.

[0009] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A pure ammonia engine idle speed stabilization system includes an engine body, an intake system, an ammonia supply system, a high-energy ignition device, an accessory loading assembly, and an ECU; wherein: The intake system is connected to the intake end of the engine block; The ammonia supply system is connected to the intake system and serves as the sole fuel source for the engine. The engine block is equipped with a high compression ratio tumble shallow basin combustion chamber; The high-energy ignition device is used to ignite the ammonia-air mixture entering the high-compression-ratio tumble shallow-bowl combustion chamber; The accessory loading component is connected to the engine body via a transmission and is used to apply load torque to the engine body; The ECU is electrically connected to the ammonia supply system, the high-energy ignition device, and the accessory loading assembly, and is used to control the pure ammonia combustion output and the load torque of the accessory loading assembly according to the engine speed signal and the engine torque signal, so that the load torque offsets the positive output torque of the engine body under idling conditions.

[0010] Preferably, the intake system includes an air filter, a turbocharger, an intercooler, a mixer, and an intake manifold connected in sequence; wherein: The intake manifold is connected to the intake end of the engine block; The ammonia supply system is connected to the ammonia inlet of the mixer.

[0011] Preferably, the accessory loading assembly includes a fan clutch device, a fan, an air compressor clutch device, and an air compressor; wherein: The fan is connected to the engine body via a fan clutch mechanism. The air compressor is connected to the engine body via an air compressor clutch device; The fan clutch and the air compressor clutch are electrically connected to the ECU.

[0012] Preferably, the accessory loading assembly includes a reverse-drive motor, a motor clutch device, a fan, and a fan clutch device; wherein: The reverse drive motor is connected to the engine body via a motor clutch device; The fan is connected to the engine body via a fan clutch mechanism. The motor clutch and fan clutch are electrically connected to the ECU.

[0013] Preferably, the air compressor's inlet end is connected to the air intake system via an air compressor inlet pipe; The air outlet end of the air compressor is connected to the air outlet pipeline of the air compressor; The air compressor's outlet pipe is connected in sequence to the dryer and the air tank.

[0014] Preferably, the compression ratio of the high compression ratio tumble shallow bowl combustion chamber is 23 to 25; High-energy ignition devices include ignition coils, spark plugs, and spacers; Spark plugs are mounted on the cylinder head of the engine block via spacers; The ignition energy of the high-energy ignition device is mJ.

[0015] An ammonia supply system for supplying ammonia to a pure ammonia engine includes an ammonia tank, a PTC heater, a buffer tank, an ammonia filter, an ammonia injection valve, and a mixer; wherein: The outlet of the ammonia tank is connected in sequence to the PTC heater, buffer tank, ammonia filter and ammonia injection valve via an ammonia supply pipeline. The outlet of the ammonia injection valve is connected to the ammonia inlet of the mixer; The air inlet of the mixer is connected to the intake system of the pure ammonia engine; The mixer's air outlet is connected to the intake manifold.

[0016] Preferably, the ammonia filter has a filtration efficiency of not less than 99% for particles with a diameter of 0.3 μm; An ammonia leak sensor is installed on the outside of the ammonia supply pipeline and / or ammonia injection valve; The ammonia leak sensor is electrically connected to the ECU, which is used to cut off the ammonia supply when the ammonia concentration detected by the ammonia leak sensor reaches a preset alarm value.

[0017] Preferably, it further includes a heat exchange device, an air compressor outlet bypass valve, an air compressor outlet bypass pipeline, a post-heat exchange outlet pipeline, and a check valve; wherein: The heat exchange device includes an ammonia supply channel and a heat source channel; The ammonia supply channel is connected in series between the ammonia filter and the ammonia injection valve; The inlet of the heat source flow channel is connected to the air compressor outlet pipeline through the air compressor outlet bypass pipeline; The air compressor outlet bypass valve is installed on the air compressor outlet bypass pipeline; The outlet of the heat source channel is connected to the dryer through the heat exchange outlet pipe; The one-way valve is installed on the exhaust pipe after heat exchange.

[0018] A method for stabilizing the idle speed of a pure ammonia engine, applied to the aforementioned pure ammonia engine idle speed stabilization system, includes the following steps: S1. The ECU acquires engine speed and engine torque signals, and determines whether the engine has entered idle condition based on engine speed and engine output torque. S2. After the engine enters the idling condition, the PTC heater is controlled to heat the ammonia fuel, so that the ammonia fuel passes through the buffer tank for pressure stabilization, the ammonia filter for filtration, and the ammonia injection valve for injection in sequence, and is mixed with air in the mixer. S3. Control the ammonia injection pressure to 190kPa~210kPa, the air-fuel ratio to 0.95~1.05, and the ignition angle to 50°~52°. Ignite the ammonia-air mixture entering the high compression ratio tumble shallow basin combustion chamber through a high-energy ignition device. S4. Based on the difference between the engine output torque and the preset target idle speed output torque, control the air compressor clutch and / or fan clutch to engage, or control the motor clutch and / or fan clutch to engage, so as to apply load torque to the engine body and counteract the positive output torque generated by pure ammonia combustion. S5. Based on engine speed, engine output torque, and cycle fluctuation rate, the ammonia injection quantity, ignition parameters, and load torque of accessory loading components are adjusted to ensure that the cycle fluctuation rate is less than 3%. S6. Detect the temperature and pressure of ammonia gas upstream of the ammonia injection valve. When the temperature and pressure of ammonia gas meet the preset secondary liquefaction conditions, control the air compressor outlet bypass valve to open, so that the high-temperature gas output by the air compressor enters the heat exchange device to heat the ammonia gas flowing to the ammonia injection valve. S7. Detect the ammonia concentration in the ammonia supply area. When the ammonia concentration reaches the preset alarm value, close the ammonia injection valve to cut off the ammonia supply.

[0019] The present invention can achieve the following beneficial effects: 1. This invention uses ammonia as the sole fuel source for the engine body, eliminating the need for a diesel ignition system or a hydrogen fuel auxiliary supply system. This reduces the number of components required for the simultaneous storage, transportation, and control of multiple fuels, simplifying the engine's fuel supply structure.

[0020] 2. This invention improves the temperature and pressure at the end of compression by setting a high compression ratio tumble shallow basin combustion chamber with a compression ratio of 23 to 25, and improves the movement and distribution of the ammonia-air mixture in the combustion chamber by using tumble airflow, which is beneficial to improving the ignition conditions of pure ammonia fuel under idling and low load conditions.

[0021] 3. This invention uses a high-energy ignition device and forms an ignition structure suitable for pure ammonia combustion through a spark plug, ignition coil and spacer. It can adapt to the high ignition energy requirements of ammonia fuel and improve the ignition reliability and combustion stability under idling conditions.

[0022] 4. This invention uses a mixer to mix heated, pressure-stabilized, and filtered ammonia with pressurized and intercooled air before it enters the intake manifold. This reduces the phenomenon of localized overly rich or overly lean mixtures and minimizes the impact of uneven ammonia supply to each cylinder on cycle stability.

[0023] 5. The present invention applies a controllable load torque to the engine body through the accessory loading component, so that the load torque generated by the fan, air compressor or reverse drive motor can offset the positive output torque generated by the pure ammonia engine when idling and burning stably, thereby alleviating the contradiction that "reducing the amount of ammonia injection will lead to unstable combustion, while maintaining stable combustion will generate positive output torque".

[0024] 6. This invention utilizes the ECU to perform joint feedback regulation of ammonia injection quantity, ignition parameters and accessory load torque based on engine speed, engine output torque and cycle fluctuation rate. It can simultaneously regulate combustion output and external load, keep engine idle speed and output torque within the target range, and keep cycle fluctuation rate less than 3%.

[0025] 7. This invention heats, stabilizes, filters, and meters ammonia fuel sequentially through a PTC heater, a buffer tank, an ammonia filter, and an ammonia injection valve. This reduces the impact of ammonia supply temperature fluctuations, pressure fluctuations, and particulate impurities on injection stability, thereby improving the continuity and reliability of the ammonia supply system.

[0026] 8. When there is a risk of secondary liquefaction upstream of the ammonia injection valve, the present invention introduces high-temperature compressed air output from the air compressor into the heat exchange device to heat the ammonia in the ammonia supply channel, which can reduce the risk of secondary liquefaction of ammonia before injection and reduce the fluctuation of injection volume, uneven mixing and combustion deterioration caused by changes in gas-liquid state.

[0027] 9. The present invention delivers the compressed air after heat exchange to the dryer and the air tank through a one-way valve. While using the waste heat of the air compressor to heat the ammonia, it does not affect the continued use of the compressed air in the vehicle's air circuit system, and can reduce the temperature of the compressed air before entering the dryer, thereby improving the heat utilization rate.

[0028] 10. This invention reduces the safety risks of ammonia leakage to vehicles, equipment and personnel by installing an ammonia leak sensor around the ammonia supply pipeline and ammonia injection valve and linking it with the ECU. When the ammonia concentration reaches a preset alarm value, the ammonia injection valve is closed, the ammonia supply is cut off and an alarm is triggered. Attached Figure Description

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 The system structure of a pure ammonia engine idle speed stabilization system; Figure 2 This is a system structure for an ammonia supply system; Figure 3 This is a diagram of the external structure of the engine of the present invention; Figure 4 This is a structural diagram of the mixer of the present invention; Figure 5 This is a structural diagram of another alternative implementation of a pure ammonia engine idle speed stabilization system.

[0030] In the diagram: 1-Air filter, 2-Turbocharger, 3-Intercooler, 4-Mixer, 5-Intake manifold, 6-Engine body, 7-Engine exhaust manifold, 8-Ammonia tank, 9-PTC heater, 10-Buffer tank, 11-Ammonia filter, 12-Ammonia injection valve, 13-Fan clutch, 14-Fan, 15-Air compressor clutch, 16-Air compressor, 17-Air compressor intake line, 18-Air compressor outlet line, 19-Dry air filter. 20-Air tank, 21-Engine speed signal, 22-Engine torque signal, 23-ECU, 30-Heat exchange device, 31-Air compressor outlet bypass valve, 32-Air compressor outlet bypass pipeline, 33-Heat exchange outlet pipeline, 34-One-way valve, 35-Ammonia inlet pipe, 36-Ammonia leak sensor, 37-Ammonia injection valve, 38-Connecting pipe, 39-Ammonia ignition coil, 40-Spare motor, 41-Ammonia filter. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments. Without departing from the concept of the present invention, any equivalent substitutions or conventional adjustments made by those skilled in the art to the materials, dimensions, connection methods, control parameters, and arrangement of the components should fall within the protection scope of the present invention.

[0032] An idle speed stabilization system for a pure ammonia engine has the following specific structure: like Figure 1 and Figure 5 As shown, the present invention includes an engine body 6, an intake system, an ammonia supply system, a high-energy ignition device, an accessory loading assembly, and an ECU 23. The intake system is connected to the intake end of the engine body 6, and the ammonia supply system is connected to the intake system and serves as the sole fuel source for the engine body 6. The engine body 6 is equipped with a high-compression ratio tumble shallow-bowl combustion chamber. The high-energy ignition device is used to ignite the ammonia-air mixture entering the high-compression ratio tumble shallow-bowl combustion chamber. The accessory loading assembly is drive-connected to the engine body 6 and is used to apply load torque to the engine body 6. The ECU 23 is electrically connected to the ammonia supply system, the high-energy ignition device, and the accessory loading assembly, and is used to control the pure ammonia combustion output and the load torque of the accessory loading assembly according to the engine speed signal 21 and the engine torque signal 22, so that the load torque offsets the positive output torque of the engine body 6 under idling conditions.

[0033] This invention uses pure ammonia as the sole fuel for the engine body 6, without a hydrogen fuel supply system or a diesel ignition system. Due to the low flame propagation speed, high ignition energy requirement, and narrow combustible range of ammonia fuel, combustion instability is prone to occur under low-load idling conditions. This invention improves the compression endpoint temperature and pressure through a high-compression ratio tumble shallow-bowl combustion chamber, enhances ignition energy through a high-energy ignition device, improves the mixing uniformity of ammonia and air through a mixer 4, and consumes the positive output torque of the engine body 6 at idle through an accessory loading component. These measures, combined with improved combustion organization and load matching, achieve stable idling for the pure ammonia engine.

[0034] The intake system includes an air filter 1, a turbocharger 2, an intercooler 3, a mixer 4, and an intake manifold 5, connected in sequence. The air filter 1 filters the air entering the intake system; the turbocharger 2 increases the intake pressure; the intercooler 3 reduces the temperature of the pressurized air; the mixer 4 mixes the air with ammonia; and the intake manifold 5 distributes the ammonia-air mixture to each cylinder of the engine block 6. The exhaust end of the engine block 6 is connected to the engine exhaust manifold 7, through which the exhaust gases are discharged.

[0035] The mixer 4 has an air inlet, an ammonia inlet, and a mixed gas outlet. The air inlet is connected to the intercooler 3, the ammonia inlet is connected to the outlet of the ammonia injection valve 12, and the mixed gas outlet is connected to the intake manifold 5. The ammonia injection valve 12 injects heated, pressure-stabilized, and filtered ammonia into the mixer 4. Air and ammonia are premixed within the mixer 4 before entering the intake manifold 5. Figure 4 As shown, the mixer 4 forms an internal channel structure for air flow and ammonia mixing. By setting the mixer 4 before entering the cylinder, the uniformity of ammonia and air mixing can be improved, and combustion fluctuations caused by local over-rich or over-lean mixtures can be reduced.

[0036] The engine block 6 is equipped with a high-compression-ratio tumble-flow shallow-bowl combustion chamber. Preferably, the compression ratio of the high-compression-ratio tumble-flow shallow-bowl combustion chamber is 23-25. This combustion chamber can be formed by the combined action of the cylinder head combustion chamber area, the tumble airflow organization formed by the intake manifold, and the shallow-bowl-shaped recess on the piston top. After the ammonia-air mixture supplied by the intake system enters the cylinder, it forms a strong in-cylinder motion under the action of the tumble airflow. The shallow-bowl-shaped combustion chamber is used to constrain the distribution of the mixture around the spark plug and reduce the quenching space at the side clearance and top clearance, thereby improving the ignition conditions of pure ammonia fuel and reducing the escape of unburned ammonia.

[0037] The high-energy ignition device includes an ignition coil, a spark plug, and a spacer. The spark plug is mounted on the cylinder head of the engine block 6 via the spacer, and the ignition end of the spark plug extends into the high-compression ratio tumble shallow-bowl combustion chamber or is located in the effective ignition area of ​​the combustion chamber. The ignition coil is connected to the spark plug and is used to provide ignition energy to the spark plug. Preferably, the ignition energy of the high-energy ignition device is 130mJ. By increasing the ignition energy, the device can adapt to the high ignition energy requirements of ammonia fuel, and improve the ignition reliability and combustion stability under low-load idling conditions.

[0038] like Figure 3 As shown, the ammonia supply pipelines and high-energy ignition devices are arranged along the outside of the engine body 6. The mixer 4 is connected to the intake side of the engine body 6. The high-energy ignition devices are set for each cylinder of the engine body 6 to form an external arrangement relationship corresponding to the pure ammonia intake, mixing and ignition process.

[0039] The accessory loading assembly can adopt a combination of air compressor and fan loading. Specifically, the accessory loading assembly includes a fan clutch device 13, a fan 14, an air compressor clutch device 15, and an air compressor 16. The fan 14 is driven to the engine body 6 via the fan clutch device 13, and the air compressor 16 is driven to the engine body 6 via the air compressor clutch device 15. The fan clutch device 13 and the air compressor clutch device 15 are electrically connected to the ECU 23. The ECU 23 controls the engagement or disengagement of the fan clutch device 13 and the air compressor clutch device 15 according to the engine speed signal 21 and the engine torque signal 22, thereby controlling the load torque applied to the engine body 6 by the fan 14 and the air compressor 16.

[0040] In this structure, the air compressor 16's intake end is connected to the intake system via air compressor intake pipe 17, and the air compressor 16's outlet end is connected to air compressor outlet pipe 18, which in turn connects to dryer 19 and air tank 20. When the air compressor 16 is loaded, it can provide compressed air to the vehicle's air system and also serve as a controllable accessory load for the engine body 6. When the fan 14 is loaded, it can consume part of the engine body 6's output torque through fan clutch device 13. Through the staged or combined loading of air compressor 16 and fan 14, the positive output torque generated by pure ammonia combustion can be offset under idling conditions.

[0041] The accessory loading component can also adopt a combination of a reverse-drive motor and a fan. Specifically, the accessory loading component includes a reverse-drive motor, a motor clutch, a fan 14, and a fan clutch 13. The reverse-drive motor is connected to the engine body 6 via the motor clutch, and the fan 14 is connected to the engine body 6 via the fan clutch 13. Both the motor clutch and the fan clutch 13 are electrically connected to the ECU 23. Under idling conditions, the ECU 23 controls the motor clutch to engage, causing the reverse-drive motor to apply a reverse-drive load to the engine body 6, while simultaneously controlling the fan clutch 13 to engage, causing the fan 14 to participate in load loading. Through the combined action of the reverse-drive motor and the fan 14, the positive output torque generated by the engine body 6 after stable combustion of pure ammonia can be counteracted, bringing the idling output close to the target state.

[0042] An ammonia supply system, the specific structure of which is as follows: like Figure 1 and Figure 2 As shown, the ammonia supply system of the present invention is used to supply ammonia to a pure ammonia engine, including an ammonia tank 8, a PTC heater 9, a buffer tank 10, an ammonia filter 11, an ammonia injection valve 12, and a mixer 4. The outlet of the ammonia tank 8 is connected sequentially to the PTC heater 9, the buffer tank 10, the ammonia filter 11, and the ammonia injection valve 12 via an ammonia supply pipeline; the outlet of the ammonia injection valve 12 is connected to the ammonia inlet of the mixer 4; the air inlet of the mixer 4 is connected to the air intake system of the pure ammonia engine; and the mixed gas outlet of the mixer 4 is connected to the air intake manifold 5.

[0043] Ammonia tank 8 is used to store ammonia fuel. A PTC heater 9 is located downstream of ammonia tank 8 to heat the ammonia fuel, ensuring it enters the subsequent ammonia supply line in a gaseous or stable state suitable for injection and mixing. A buffer tank 10 is located downstream of the PTC heater 9 to buffer pressure fluctuations in the ammonia supply line, making the ammonia pressure entering the ammonia injection valve 12 more stable. An ammonia filter 11 is located between the buffer tank 10 and the ammonia injection valve 12 to filter particulate impurities in the ammonia fuel and pipeline, preventing impurities from clogging the ammonia injection valve 12. Preferably, the ammonia filter 11 has a filtration efficiency of not less than 99% for particles with a diameter of 0.3 μm.

[0044] Ammonia injection valve 12 is located upstream of mixer 4 or connected to the ammonia inlet of mixer 4, and is used to inject ammonia into mixer 4 according to the control commands of ECU 23. Ammonia injection valve 12 can be selected from those suitable for gaseous ammonia injection, and its operating pressure can be selected according to the engine operating conditions. During idle speed stabilization control, ECU 23 preferably controls the ammonia injection pressure to be 190 kPa to 210 kPa, so that the ammonia injection quantity matches the idle air intake quantity, thereby maintaining the air-fuel ratio and combustion stability.

[0045] An ammonia leak sensor is installed on the outside of the ammonia supply line and / or ammonia injection valve 12. The ammonia leak sensor is electrically connected to ECU 23 and is used to detect the ammonia concentration around the ammonia supply area. When the ammonia concentration detected by the ammonia leak sensor reaches a preset alarm value, ECU 23 closes the ammonia injection valve 12 or cuts off the control valve on the ammonia supply line to cut off the ammonia supply. By installing the ammonia leak sensor, the system can be protected in time in case of ammonia leakage, improving the operational safety of the pure ammonia engine.

[0046] In a preferred embodiment, such as Figure 2 As shown, the ammonia supply system also includes a heat exchanger 30, an air compressor outlet bypass valve 31, an air compressor outlet bypass pipeline 32, a post-heat exchange outlet pipeline 33, and a one-way valve 34. The heat exchanger 30 includes an ammonia supply channel and a heat source channel. The ammonia supply channel is connected in series between the ammonia filter 11 and the ammonia injection valve 12. The inlet of the heat source channel is connected to the air compressor outlet pipeline 18 through the air compressor outlet bypass pipeline 32. The air compressor outlet bypass valve 31 is installed on the air compressor outlet bypass pipeline 32. The outlet of the heat source channel is connected to the dryer 19 through the post-heat exchange outlet pipeline 33. The one-way valve 34 is installed on the post-heat exchange outlet pipeline 33.

[0047] When the temperature of the ammonia gas upstream of the ammonia injection valve 12 decreases or the pressure conditions pose a risk of secondary liquefaction, the ECU 23 controls the air compressor outlet bypass valve 31 to open, allowing the high-temperature gas output from the air compressor 16 to enter the heat source channel of the heat exchanger 30 via the air compressor outlet bypass pipe 32. The high-temperature compressed air in the heat source channel exchanges heat with the ammonia gas in the ammonia supply channel, heating the ammonia gas flowing towards the ammonia injection valve 12 and preventing secondary liquefaction of the ammonia gas before the ammonia injection valve 12. The compressed air after heat exchange enters the dryer 19 via the heat exchange outlet pipe 33 and the one-way valve 34, and then enters the air storage tank 20. This structure utilizes the residual heat from the air compressor 16 to heat the ammonia gas and reduces the temperature of the compressed air before entering the dryer 19, which helps improve the reliability of the vehicle's air circuit system.

[0048] A method for stabilizing the idle speed of a pure ammonia engine, the specific method is as follows: The pure ammonia engine idle speed stability control method of the present invention is applied to the above-mentioned pure ammonia engine idle speed stability system. This method uses ECU23 to coordinate the control of ammonia supply, ignition parameters, accessory loading, and secondary liquefaction prevention, enabling the engine body 6 to maintain stable idle speed under pure ammonia as the sole fuel.

[0049] S1 and ECU23 acquire engine speed signal 21 and engine torque signal 22, and determine whether the engine has entered idle condition based on engine speed and engine output torque.

[0050] Specifically, engine speed signal 21 reflects the current speed of engine body 6, and engine torque signal 22 reflects the current output torque of engine body 6. ECU 23 compares the engine speed with a preset idle speed range and the engine output torque with a preset idle torque range. When the engine speed is within the idle speed range, and the driver does not request acceleration or the engine output torque is within the idle judgment range, ECU 23 determines that the engine has entered idle operation.

[0051] S2. After the engine enters the idling condition, the ECU23 controls the PTC heater 9 to heat the ammonia fuel, so that the ammonia fuel passes through the buffer tank 10 for pressure stabilization, the ammonia filter 11 for filtration, and the ammonia injection valve 12 for injection in sequence, and is mixed with air in the mixer 4.

[0052] Specifically, after being supplied from the ammonia tank 8, the ammonia fuel first enters the PTC heater 9, which heats the fuel to reduce the risk of insufficient vaporization or secondary liquefaction due to excessively low temperatures. The heated ammonia then enters the buffer tank 10, which reduces the impact of ammonia supply pressure fluctuations on injection stability. Subsequently, the ammonia enters the ammonia filter 11, which filters out particulate impurities. The filtered ammonia then enters the ammonia injection valve 12 and is injected into the mixer 4. Air passes through the air filter 1, turbocharger 2, and intercooler 3 before entering the mixer 4, where it mixes with the ammonia to form an ammonia-air mixture, which then enters the engine block 6 via the intake manifold 5.

[0053] S3 and ECU23 control the ammonia injection pressure to be 190kPa~210kPa, the air-fuel ratio to be 0.95~1.05, and the ignition angle to be 50°~52°, and ignite the ammonia-air mixture entering the high compression ratio tumble shallow basin combustion chamber through a high-energy ignition device.

[0054] Specifically, ECU23 adjusts the injection quantity and duration of ammonia injection valve 12 based on engine speed, engine torque, intake air volume, and ammonia pressure to match the amount of ammonia entering mixer 4 with the amount of air. After the ammonia-air mixture enters the high-compression ratio tumble shallow-bowl combustion chamber, the high compression ratio and tumble airflow create a temperature, pressure, and flow state favorable for pure ammonia ignition. ECU23 controls the high-energy ignition device to trigger ignition at an ignition angle of 50°–52°. The ignition coil provides ignition energy to the spark plug, which ignites the ammonia-air mixture, achieving pure ammonia fuel combustion.

[0055] S4 and ECU23 control the accessory loading component to apply load torque to the engine body 6 based on the difference between the engine output torque and the preset target idle speed output torque, so as to counteract the positive output torque generated by pure ammonia combustion.

[0056] Specifically, after the pure ammonia fuel has stabilized and burned, the engine block 6 may still generate positive output torque under idling conditions. To make the idling output torque close to the preset target idling output torque, the ECU 23 determines the required load torque based on the difference between the engine output torque and the preset target idling output torque. When the accessory loading assembly uses a combination of air compressor and fan loading, the ECU 23 controls the air compressor clutch 15 and / or fan clutch 13 to engage, thus loading the air compressor 16 and / or fan 14; when the accessory loading assembly uses a combination of reverse motor and fan loading, the ECU 23 controls the motor clutch 15 and / or fan clutch 13 to engage, thus loading the reverse motor and / or fan 14. Through the above load loading, the load torque generated by the accessory loading assembly offsets the positive output torque of the engine block 6 under idling conditions, thereby reducing idling speed fluctuations.

[0057] S5 and ECU23 adjust the ammonia injection quantity, ignition parameters, and load torque of accessory loading components based on engine speed, engine output torque, and cycle fluctuation rate, so that the cycle fluctuation rate is less than 3%.

[0058] Specifically, ECU23 continuously collects engine speed signal 21 and engine torque signal 22, and determines the cycle fluctuation rate based on engine speed fluctuations, engine output torque fluctuations, or combustion cycle stability parameters. When the cycle fluctuation rate increases or the engine idle speed deviates from the preset range, ECU23 jointly adjusts the ammonia injection quantity, ignition angle, and accessory loading torque. If the engine output torque is too high, ECU23 increases the accessory loading torque or appropriately corrects the ammonia injection quantity; if the engine output torque is too low or the speed decreases, ECU23 reduces the accessory loading torque or appropriately increases the ammonia injection quantity. Through closed-loop feedback, the idle combustion and output of the pure ammonia engine remain stable.

[0059] S6 and ECU23 detect the temperature and pressure of ammonia gas upstream of ammonia injection valve 12. When the temperature and pressure of ammonia gas meet the preset secondary liquefaction conditions, they control the air compressor outlet bypass valve 31 to open, so that the high-temperature gas output by air compressor 16 enters heat exchange device 30 to heat the ammonia gas flowing to ammonia injection valve 12.

[0060] Specifically, after passing through the ammonia tank 8, PTC heater 9, buffer tank 10, ammonia filter 11, and connecting pipelines in the ammonia supply pipeline, the ammonia gas may experience a temperature drop due to changes in ambient temperature and pressure, or heat exchange in the pipeline. When the ECU 23 determines that there is a risk of secondary liquefaction based on the ammonia temperature and pressure upstream of the ammonia injection valve 12, the ECU 23 controls the air compressor outlet bypass valve 31 to open. The high-temperature compressed air output from the air compressor 16 enters the heat source channel of the heat exchange device 30 through the air compressor outlet bypass pipeline 32, and exchanges heat with the ammonia gas in the ammonia supply channel, raising the temperature of the ammonia gas before entering the ammonia injection valve 12. The compressed air after heat exchange enters the dryer 19 through the heat exchange outlet pipeline 33 and the one-way valve 34, preventing the compressed air from reversing into the heat exchange device 30.

[0061] S7 and ECU23 detect the ammonia concentration in the ammonia supply area. When the ammonia concentration reaches the preset alarm value, the ammonia injection valve 12 is closed to cut off the ammonia supply.

[0062] Specifically, the ammonia leak sensor is located near the ammonia supply line, ammonia injection valve 12, and / or mixer 4 to detect the ammonia concentration in the ammonia supply area. After receiving the signal from the ammonia leak sensor, ECU 23 compares the detected ammonia concentration with a preset alarm value. When the ammonia concentration reaches the preset alarm value, ECU 23 closes the ammonia injection valve 12 and can simultaneously control the shut-off valve on the ammonia supply line to close, stopping the heating output of PTC heater 9 and triggering a fault alarm to ensure the safe operation of the ammonia supply system and the engine.

[0063] Example 1: like Figure 1 As shown, in this embodiment, the pure ammonia engine idle speed stabilization system adopts a combined air compressor and fan loading structure. The intake system includes an air filter 1, a turbocharger 2, an intercooler 3, a mixer 4, and an intake manifold 5; the ammonia supply system includes an ammonia tank 8, a PTC heater 9, a buffer tank 10, an ammonia filter 11, an ammonia injection valve 12, and a mixer 4; the accessory loading components include a fan clutch device 13, a fan 14, an air compressor clutch device 15, and an air compressor 16.

[0064] After the engine block 6 enters idle mode, the ECU 23 controls the ammonia injection valve 12 to inject ammonia and controls the high-energy ignition device to ignite the ammonia-air mixture. After stable ignition of pure ammonia combustion, the engine block 6 generates positive output torque. Based on the engine torque signal 22, the ECU 23 controls the air compressor clutch 15 and fan clutch 13 to engage, causing the air compressor 16 and fan 14 to consume engine output power. The load torque of the air compressor 16 and fan 14 counteracts the positive output torque generated by pure ammonia combustion, thus stabilizing the engine idle speed. This embodiment is suitable for applications where the vehicle is already equipped with an air compressor 16 and fan 14, achieving stable idle speed without adding additional independent load equipment.

[0065] Example 2: The difference between this embodiment and Embodiment 1 is that the accessory loading component adopts a combined loading structure of a reverse-drive motor and a fan. The reverse-drive motor is connected to the engine body 6 via a motor clutch device, and the fan 14 is connected to the engine body 6 via a fan clutch device 13. After the engine body 6 enters the idling condition, the ECU 23 controls the motor clutch device to engage based on the engine speed signal 21 and the engine torque signal 22, so that the reverse-drive motor applies a reverse load to the engine body 6, and at the same time controls the fan clutch device 13 to engage, so that the fan 14 participates in the loading.

[0066] In this embodiment, the reverse-drive motor provides adjustable load torque according to the control commands of the ECU 23, and the fan 14 provides auxiliary load torque. The ECU 23 adjusts the load of the reverse-drive motor and the engagement state of the fan 14 based on the difference between the engine output torque and the preset target idle speed output torque, thereby maintaining stable engine idle speed and output torque. This embodiment is suitable for engine systems with reverse-drive motor capabilities or requiring more precise load adjustment.

[0067] Example 3: like Figure 2 As shown, this embodiment adds an ammonia heat exchange anti-secondary liquefaction structure based on Embodiment 1. The ammonia supply system also includes a heat exchange device 30, an air compressor outlet bypass valve 31, an air compressor outlet bypass pipeline 32, a post-heat exchange outlet pipeline 33, and a one-way valve 34. The ammonia supply channel of the heat exchange device 30 is connected in series between the ammonia filter 11 and the ammonia injection valve 12, and the heat source channel of the heat exchange device 30 is bypassed to the air compressor outlet pipeline 18.

[0068] When ECU23 determines that there is a risk of secondary liquefaction of ammonia upstream of ammonia injection valve 12, ECU23 controls the air compressor outlet bypass valve 31 to open, allowing the high-temperature compressed air output from air compressor 16 to enter heat exchanger 30. The high-temperature compressed air heats the ammonia in the ammonia supply channel, ensuring that the ammonia is in a suitable state for injection before entering ammonia injection valve 12, thus preventing secondary liquefaction of ammonia upstream of the injection valve, which could lead to uneven injection, localized temperature drop, poor combustion, or increased emissions of unburned ammonia. The compressed air after heat exchange enters dryer 19 and air tank 20 via check valve 34 for use in the vehicle's air system. This embodiment can simultaneously utilize the waste heat of the air compressor to stabilize the ammonia supply state and reduce the air compressor outlet temperature.

[0069] Example 4: like Figure 5As shown, this embodiment provides another optional accessory loading structure for the pure ammonia engine idle speed stabilization system. Compared with Embodiment 1, this embodiment does not use the air compressor 16 as the idle speed loading component, but instead uses a backup motor 40 as a reverse drag motor. The backup motor 40 is connected to the engine body 6 via a motor clutch device, and the fan 14 is still connected to the engine body 6 via a fan clutch device 13. The motor clutch device and the fan clutch device 13 are electrically connected to the ECU 23 respectively.

[0070] After the engine body 6 enters the idling condition, the ECU 23 determines the required load torque based on the engine speed signal 21 and the engine torque signal 22. When the positive output torque of the engine body 6 is higher than the preset target idling output torque, the ECU 23 controls the motor clutch to engage, so that the backup motor 40 absorbs part of the output power of the engine body 6 in a reverse drag manner; when the required load torque increases further, the ECU 23 can also control the fan clutch 13 to engage, so that the fan 14 participates in the load.

[0071] During load adjustment, ECU23 adjusts the reverse load of the standby motor 40 based on engine speed, engine output torque, and cycle fluctuation rate, and coordinates the engagement state of fan 14 to match the load torque generated by the accessory loading component with the positive output torque generated by stable combustion of pure ammonia. Compared with the implementation using air compressor 16 for loading, this embodiment can achieve continuous or graded load adjustment through standby motor 40, and is suitable for application scenarios where no air compressor loading branch is configured, air compressor load is not suitable for idle speed adjustment, or higher load adjustment accuracy is required.

[0072] Since this embodiment does not utilize the high-temperature exhaust air from the air compressor 16 as a heat exchange source, Figure 2 The structure shown that uses the waste heat from the air compressor outlet for ammonia heat exchange is not a necessary component of this embodiment; when it is still necessary to heat the ammonia upstream of the ammonia injection valve 12 to prevent secondary liquefaction, the PTC heater 9 can continue to perform the heating function.

[0073] Through the above embodiments, this invention uses pure ammonia as the sole fuel source for the engine body 6. A stable ammonia supply is ensured through a PTC heater 9, a buffer tank 10, an ammonia filter 11, and an ammonia injection valve 12. The mixer 4 improves the uniformity of ammonia-air mixing. A high compression ratio tumble-flow shallow-bowl combustion chamber (23-25) and a 130mJ high-energy ignition device improve the ignition conditions for pure ammonia. An auxiliary load is formed by the air compressor 16, fan 14, or a backup motor 40 used as a reverse-drive motor to counteract the positive output torque generated by pure ammonia combustion during idling. When using an air compressor loading branch, the heat exchanger 30 can also utilize the heat from the air compressor exhaust to heat the ammonia, reducing the risk of secondary ammonia liquefaction. Therefore, this invention can improve the idling stability, ammonia supply reliability, and operational safety of a pure ammonia engine without introducing a hydrogen fuel or diesel ignition system.

[0074] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the scope of protection of the present invention. The scope of protection of the present invention should be determined by the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims; equivalent substitutions and conventional improvements made within this scope are all within the scope of protection of the present invention.

Claims

1. A pure ammonia engine idle speed stabilization system, characterized in that, Includes the engine block (6), intake system, ammonia supply system, high-energy ignition device, accessory loading assembly, and ECU (23); among which: The intake system is connected to the intake end of the engine body (6); The ammonia supply system is connected to the intake system and serves as the sole fuel source for the engine body (6); The engine body (6) is equipped with a high compression ratio tumble shallow basin combustion chamber; The high-energy ignition device is used to ignite the ammonia-air mixture entering the high-compression-ratio tumble shallow-bowl combustion chamber; The accessory loading component is connected to the engine body (6) for applying load torque to the engine body (6); The ECU (23) is electrically connected to the ammonia supply system, the high-energy ignition device and the accessory loading assembly respectively, and is used to control the pure ammonia combustion output and the load torque of the accessory loading assembly according to the engine speed signal (21) and the engine torque signal (22), so that the load torque offsets the positive output torque of the engine body (6) under idling conditions.

2. The pure ammonia engine idle speed stabilization system according to claim 1, characterized in that, The intake system includes an air filter (1), a turbocharger (2), an intercooler (3), a mixer (4), and an intake manifold (5) connected in sequence; wherein: The intake manifold (5) is connected to the intake end of the engine body (6); The ammonia supply system is connected to the ammonia inlet of the mixer (4).

3. The pure ammonia engine idle speed stabilization system according to claim 1, characterized in that, The attachment loading components include a fan clutch (13), a fan (14), an air compressor clutch (15), and an air compressor (16); wherein: The fan (14) is connected to the engine body (6) via a fan clutch device (13); The air compressor (16) is connected to the engine body (6) via the air compressor clutch device (15); The fan clutch (13) and the air compressor clutch (15) are electrically connected to the ECU (23).

4. The pure ammonia engine idle speed stabilization system according to claim 1, characterized in that, The attachment loading components include a reverse-drive motor, a motor clutch, a fan (14), and a fan clutch (13); wherein: The reverse drive motor is connected to the engine body (6) via a motor clutch device; The fan (14) is connected to the engine body (6) via a fan clutch device (13); The motor clutch and the fan clutch (13) are electrically connected to the ECU (23).

5. The pure ammonia engine idle speed stabilization system according to claim 3, characterized in that, The air intake end of the air compressor (16) is connected to the air intake system through the air compressor intake pipe (17); The air outlet of the air compressor (16) is connected to the air outlet pipe (18). The air compressor outlet pipe (18) is connected in sequence to the dryer (19) and the air tank (20).

6. The pure ammonia engine idle speed stabilization system according to claim 1, characterized in that, High-energy ignition devices include ignition coils, spark plugs, and spacers; The spark plug is mounted on the cylinder head of the engine body (6) via a spacer.

7. The pure ammonia engine idle speed stabilization system according to claim 1, characterized in that, The ammonia supply system includes an ammonia tank (8), a PTC heater (9), a buffer tank (10), an ammonia filter (11), an ammonia injection valve (12), and a mixer (4); wherein: The outlet of the ammonia tank (8) is connected in sequence to the PTC heater (9), buffer tank (10), ammonia filter (11) and ammonia injection valve (12) via the ammonia supply pipeline; The outlet of the ammonia injection valve (12) is connected to the ammonia inlet of the mixer (4); The air inlet of the mixer (4) is connected to the intake system of the pure ammonia engine; The mixed gas outlet of the mixer (4) is connected to the intake manifold (5).

8. The pure ammonia engine idle speed stabilization system according to claim 7, characterized in that, An ammonia leak sensor is provided on the outside of the ammonia supply pipeline and / or ammonia injection valve (12); The ammonia leak sensor is electrically connected to the ECU (23), which is used to cut off the ammonia supply when the ammonia concentration detected by the ammonia leak sensor reaches a preset alarm value.

9. The pure ammonia engine idle speed stabilization system according to claim 7, characterized in that, It also includes a heat exchanger (30), an air compressor outlet bypass valve (31), an air compressor outlet bypass pipeline (32), a post-heat exchange outlet pipeline (33), and a check valve (34); wherein: The heat exchange device (30) includes an ammonia supply channel and a heat source channel; The ammonia supply channel is connected in series between the ammonia filter (11) and the ammonia injection valve (12); The inlet of the heat source flow channel is connected to the air compressor outlet pipeline (18) through the air compressor outlet bypass pipeline (32); The air compressor outlet bypass valve (31) is installed on the air compressor outlet bypass pipeline (32); The outlet of the heat source flow channel is connected to the dryer (19) through the heat exchange outlet pipe (33); A one-way valve (34) is installed on the heat exchange outlet pipe (33).

10. A method for stabilizing the idle speed of a pure ammonia engine, applied to the pure ammonia engine idle speed stabilization system as described in claim 7, characterized in that, Includes the following steps: S1, ECU (23) acquires engine speed signal (21) and engine torque signal (22), and determines whether the engine has entered idle condition based on engine speed and engine output torque; S2. After the engine enters the idling condition, the PTC heater (9) is controlled to heat the ammonia fuel, so that the ammonia fuel is pressure-stabilized by the buffer tank (10) and filtered by the ammonia filter (11) and then injected into the mixer (4) by the ammonia injection valve (12). The ammonia and air mixture entering the high compression ratio tumble shallow basin combustion chamber is ignited by the high-energy ignition device. S3. Based on the difference between the engine output torque and the preset target idle speed output torque, control the accessory loading component to apply load torque to the engine body (6) to counteract the positive output torque generated by pure ammonia combustion; S4. Based on engine speed, engine output torque and cycle fluctuation rate, the ammonia injection quantity, ignition parameters and load torque of accessory loading components are adjusted to keep the engine running at a stable idle speed.

Images