Ignition system for methanol lean-burn engine, and vehicle

Abstract

Provided in the present application are an ignition system for a methanol lean-burn engine, and a vehicle. The system comprises an ignition apparatus and a control system, wherein the ignition apparatus comprises a main combustion chamber and a pre-combustion chamber, the main combustion chamber is configured with an air inlet for introducing air into the chamber and a main injector for injecting methanol, and the pre-combustion chamber is provided with a pilot injector, a multi-electrode spark plug, and a plurality of injection holes in communication with the main combustion chamber; and the control system is configured to monitor the rotational speed and air intake amount of an engine and environmental parameters in real time, so as to adjust in real time the injection pressure, injection quantity, injection timing and ignition timing of each of a main fuel and a pilot fuel, thereby achieving stable ignition under different operating condition parameters and adjusting the air-fuel ratio under each operating condition. By optimizing the ignition system, the stable ignition and efficient combustion of an engine can both be achieved under different environmental operating conditions, thereby further improving the economic performance of a methanol lean-burn engine on the basis of achieving stable ignition.

Description

An ignition system for a methanol-lean engine, and a vehicle

[0001] This application claims priority to Chinese Patent Application No. 202510351841.5, filed on March 24, 2025, entitled "An Ignition System for a Methanol Lean Engine, Vehicle", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of vehicle technology, specifically to an ignition system for a methanol lean engine and a vehicle. Background Technology

[0003] Lean burn is an engine combustion technology that achieves efficient combustion by mixing less fuel with more air than in conventional combustion. Specifically, lean burn engines operate under very high air-fuel ratio conditions (i.e., relatively little fuel in the air). This technology offers advantages such as low fuel consumption, low emissions, and low cooling heat requirements, but it also presents technical challenges such as difficulty in ignition and the need to improve combustion stability.

[0004] If this technology is to be applied to methanol engines, methanol has a high latent heat of vaporization, which absorbs a lot of heat during the formation of methanol vapor, causing the cylinder temperature to drop sharply. Moreover, methanol has a high auto-ignition temperature, making ignition relatively difficult under stoichiometric conditions. For methanol lean-burn engines, the airflow is not stable, the cylinder pressure is high, and the fuel-air concentration is thin in the ultra-lean air environment inside the cylinder, making ignition even more difficult. Summary of the Invention

[0005] This application provides an ignition system for a methanol lean-burn engine. The following is an overview of the subject matter described in detail in this application. This overview is not intended to limit the scope of the claims.

[0006] This application provides an ignition system for a methanol lean engine, including an ignition device and a control system; the ignition device includes a main combustion chamber and a pre-combustion chamber, the main combustion chamber is equipped with an air inlet for introducing air into the chamber and a main injector for injecting methanol; the pre-combustion chamber is provided with an ignition injector, a multi-electrode spark plug, and multiple injection holes connected to the main combustion chamber.

[0007] The air entering the main combustion chamber enters the pre-combustion chamber through the injection holes and mixes with the ignition fuel injected by the ignition injector to form an ignition mixture. The ignition mixture is ignited by the multi-electrode spark plug, and the resulting flame is injected into the main combustion chamber through multiple injection holes, igniting the main combustion mixture formed by the air in the main combustion chamber and the methanol injected by the main injector.

[0008] The control system is configured to monitor the engine speed, intake air volume and environmental parameters in real time to adjust the injection pressure, injection quantity, injection timing and ignition timing of the main combustion fuel and the pilot fuel in real time, so as to achieve stable ignition under different operating conditions and adjust the air-fuel ratio under each operating condition.

[0009] The environmental parameters include at least one or any combination of the engine's water temperature, ambient temperature, and ambient pressure.

[0010] In one possible implementation, the control system is configured to perform the following operations:

[0011] Monitor engine speed and intake air volume, and obtain preset values ​​for each injection parameter based on real-time speed and intake air volume and corresponding preset models;

[0012] Monitor correction parameters and obtain correction amounts for each injection parameter based on the correction parameters and the corresponding correction model, wherein the correction parameters include the environmental parameters acquired in real time;

[0013] The actual values ​​of each injection parameter are adjusted according to the preset value and the correction amount, thereby adapting to different environmental conditions by correcting and adjusting each injection parameter.

[0014] In one possible implementation, when the control system detects that either the water temperature or the ambient temperature is lower than a preset low temperature value or the previous monitoring value, it increases the injection pressure of the ignition fuel based on a correction model; when the ambient pressure is detected to be lower than a preset low pressure value, it decreases the injection pressure of the ignition fuel based on the correction model.

[0015] In one possible implementation, when the control system detects that any one or any combination of water temperature, ambient temperature, and ambient pressure is lower than a preset low value or lower than the previous monitoring value, the injection amount of the ignition fuel is increased based on a correction model, and the injection amount of the ignition fuel is controlled not to exceed a preset maximum proportion in the total fuel injection amount.

[0016] In one possible implementation, when the control system detects that any one or any combination of water temperature, ambient temperature, and ambient pressure is lower than a preset low value or lower than the previous monitoring value, the injection time of the ignition fuel is advanced based on the correction model, and the injection time of the ignition fuel has a fixed interval with the preset injection time of the main combustion fuel.

[0017] In one possible implementation, the correction parameter for the ignition timing of the ignition fuel also includes the proportion of the ignition fuel in the total fuel injection quantity, which is set according to the engine torque.

[0018] When the control system detects that any one or any combination of water temperature, ambient temperature, and ambient pressure is lower than a preset low value or lower than the monitoring value at the previous moment, the ignition time of the ignition fuel is advanced based on the correction model, and the ignition time is delayed based on the correction model as the proportion of the ignition fuel in the total fuel injection increases.

[0019] In one possible implementation, when the control system detects that any one or any combination of water temperature, ambient temperature, and ambient pressure is lower than a preset low value, the injection time of the ignition fuel is advanced based on a correction model, and the injection time of the main combustion fuel is corrected according to the actual injection time of the ignition fuel at the previous moment.

[0020] In one possible implementation, when the control system detects that any one or any combination of water temperature, ambient temperature, and ambient pressure is lower than a preset low temperature value, it increases the injection amount of the main combustion fuel based on a correction model, and controls the injection amount of the main combustion fuel to be no less than a preset minimum proportion in the total fuel injection amount.

[0021] In one possible implementation, the injection pressure of the main combustion fuel is directly proportional to the engine torque; and when the control system detects that the water temperature is lower than the previous monitoring value or lower than the preset low value, the injection pressure of the main combustion fuel is reduced based on the correction model; when either the ambient temperature or the ambient pressure is detected to be lower than the preset low value or lower than the previous monitoring value, the injection pressure of the main combustion fuel is increased based on the correction model.

[0022] In one possible implementation, the main injector is disposed within the intake manifold or offset on the cylinder head at the intake port, the pre-combustion chamber is located at the center of the cylinder head, and the plurality of injection holes include a plurality of intake side holes facing the intake port and a plurality of exhaust side holes facing away from the intake port.

[0023] The plurality of air inlet side holes and the plurality of air outlet side holes are asymmetrically arranged about the central axis of the pre-combustion chamber. The angle between the plurality of air outlet side holes and the central axis is greater than the angle between the plurality of air inlet side holes and the central axis, and the deviation of the angle is 3°-20°.

[0024] In one possible implementation, the diameter of the injection hole is 1 mm to 2.5 mm.

[0025] And / or, the volume of the pre-combustion chamber accounts for 1.5%-3% of the volume of the main combustion chamber.

[0026] And / or, the multi-electrode spark plug has at least two electrodes, and the multi-electrode spark plug is provided with a heating device, and the control system adjusts the heating time of the heating device according to the monitored water temperature and ambient temperature, so as to regulate the heating temperature of the multi-electrode spark plug and the pre-combustion chamber.

[0027] This application also provides a vehicle, including a body and a methanol lean engine disposed on the body, the methanol lean engine being configured with the ignition system described in any of the above embodiments.

[0028] The ignition system of the methanol lean-burn engine provided in this application, by setting up a pre-combustion chamber and a multi-electrode spark plug, can efficiently pre-combust in a small pre-combustion chamber. Then, high pressure is used to inject the flame into the main combustion chamber through multiple injection holes, igniting the main combustion mixture in the main combustion chamber at multiple points, efficiently and uniformly, which can effectively improve ignition effectiveness. At the same time, the control system uses real-time monitoring of engine parameters and environmental parameters to adjust the injection quantity, injection pressure, injection timing of ignition fuel and main combustion fuel, as well as the ignition timing, so that the fuel is fully mixed and then efficiently combusted. This meets the requirements of stable ignition and efficient combustion of lean fuel in the cylinder under different environmental conditions, especially under adverse conditions such as low temperature and low pressure, and ensures that the optimal air-fuel ratio is achieved under each operating condition. Thus, based on achieving stable ignition, the economic performance of the methanol lean-burn engine is further improved. Attached Figure Description

[0029] Figure 1 shows a schematic diagram of the first structure of the ignition device of the methanol lean engine in an embodiment of this application.

[0030] Figure 2 shows a second structural schematic diagram of the ignition device of the methanol lean engine in an embodiment of this application;

[0031] Figure 3 shows a schematic diagram of the control system's regulation of combustion parameters in an embodiment of this application.

[0032] In Figures 1-2: 1. Multi-electrode spark plug; 2. Ignition injector; 3. Pre-combustion chamber; 4. Throttle valve; 5. Main injector; 6. Common rail supply pipe; 7. Main combustion chamber; 8. Intake manifold. Detailed Implementation

[0033] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] Please refer to Figures 1-3. An embodiment of this application provides an ignition system for a methanol lean engine, including an ignition device and a control system. The control system is used to regulate the ignition device and implement a control method for the ignition device. This means that this application provides both an ignition device and a control method that can be implemented by the control system of the ignition device.

[0035] The ignition device includes a main combustion chamber 7 and a pre-combustion chamber 3. The main combustion chamber 7 is equipped with an air inlet and a main injector 5. The air inlet is formed by an air intake duct 8 connected to the main combustion chamber 7. A throttle valve 4 is installed on the air intake duct 8, through which air is injected into the main combustion chamber 7. The main injector 5 injects the main combustion fuel, methanol, into the main combustion chamber 7. The pre-combustion chamber 3 is equipped with an ignition injector 2 for injecting ignition fuel and a multi-electrode spark plug 1 for ignition. The pre-combustion chamber 3 has multiple injection holes connected to the main combustion chamber 7. The ignition fuel can be methanol or other flammable materials such as gasoline. When the ignition fuel is also methanol, the ignition injector 2 and the main injector 5 can be connected to the same common rail supply 6.

[0036] Multi-electrode spark plug 1 refers to a multi-electrode spark plug 1 with at least two electrodes. Multi-electrode spark plug 1 can ignite multiple times in a short period of time, effectively extending the ignition time and avoiding ignition failure.

[0037] In this process, air entering the main combustion chamber 7 enters the pre-combustion chamber 3 through injection holes and mixes with the ignition fuel injected by the ignition injector 2 to form an ignition mixture. This ignition mixture is ignited by the multi-electrode spark plug 1 to produce a flame. The flame is then injected into the main combustion chamber 7 through multiple injection holes, forming a multi-point jet ignition that ignites the main combustion mixture of air and methanol within the main combustion chamber 7. This initial ignition in the small pre-combustion chamber 3, via the multi-electrode spark plug 1, eliminates unfavorable ignition factors such as lean fuel gas and the high latent heat of methanol, ensuring successful ignition. The resulting flame, propelled by the high pressure within the pre-combustion chamber 3, is injected into the main combustion chamber 7 through multiple injection holes, achieving multi-point uniform ignition in multiple areas within the main combustion chamber 7, effectively guaranteeing a high ignition success rate and preventing ignition failure.

[0038] The control system is configured to monitor engine speed, intake air volume (engine speed can be directly measured by a speed sensor, and intake air volume can be calculated by measuring the pressure and temperature of the intake manifold) and environmental parameters in real time, and adjust various combustion parameters in real time, such as the injection pressure, injection quantity, and injection timing of the main combustion fuel and the ignition timing of the multi-electrode spark plug 1, so as to achieve stable ignition under different operating conditions and adjust the air-fuel ratio under each operating condition to the set optimal air-fuel ratio.

[0039] Among them, the environmental parameters include at least one or any combination of the engine's water temperature, ambient temperature, and ambient pressure.

[0040] In this way, the control system adjusts the injection parameters such as fuel injection timing, injection quantity, injection pressure, and ignition timing in real time based on the engine parameters and the parameters of the engine's environment. This ensures that the fuel is fully premixed before ignition, guaranteeing an optimal ignition timing. It also ensures successful ignition under various operating conditions, especially under adverse conditions such as low temperature and low pressure. Furthermore, it can maintain a high air-fuel ratio by adjusting the fuel injection parameters and ignition conditions, avoiding excessive fuel injection that could affect fuel consumption. While ensuring successful ignition under various operating conditions, it controls the air-fuel ratio within a preset optimal range, avoiding a decrease in the air-fuel ratio that would affect the economy of the lean engine.

[0041] As can be seen, the ignition system of the methanol lean engine provided in this application, by setting up a pre-combustion chamber 3 and a multi-electrode spark plug 1, can efficiently ignite the ignition fuel in the small volume of the pre-combustion chamber 3, and then inject the flame into the main combustion chamber 7 through multiple injection holes under high pressure, so as to ignite the main combustion mixture in the main combustion chamber 7 at multiple points, efficiently and uniformly, thereby improving the effectiveness of ignition. At the same time, the control system uses real-time monitoring of engine parameters and environmental parameters to adjust the injection quantity, injection pressure, injection time and ignition time of the ignition fuel and main combustion fuel in real time, so that the fuel is fully mixed before ignition and efficient combustion. This meets the requirements of stable ignition and efficient combustion of lean fuel in the cylinder under different environmental conditions, especially under adverse conditions such as low temperature and low pressure, and ensures that the optimal ignition time and air-fuel ratio are available under each operating condition. Thus, on the basis of achieving stable ignition, the economic performance of the methanol lean engine is further improved.

[0042] As shown in Figure 1, the main combustion chamber 7 has a ridge-shaped structure, meaning the cylinder head is ridge-shaped. The main injector 5 is offset on the cylinder head; for example, the nozzle is located at the air intake. Alternatively, as shown in Figure 2, the main injector 5 is located on the intake manifold 8, with the nozzle inside the intake manifold 8, and the throttle valve 4 located at the front end of the intake manifold 8. This increases the mixing time of methanol and air, improving the uniformity of their mixing.

[0043] The pre-combustion chamber 3 is located in the center of the cylinder head, that is, it is centrally located in the cylinder body. When the flame is injected, it can be injected from the center to multiple points in all directions, and the main combustion mixture can be ignited evenly at multiple points, thus achieving rapid and effective ignition.

[0044] Both the main injector 5 and the ignition injector 2 are corrosion-resistant in-cylinder direct injection devices with an injection pressure range of 200-800 bar. They can inject methanol or other ignition fuels into the pre-combustion chamber 3 and achieve good fuel-air atomization within the pre-combustion chamber 3. These injectors are made of corrosion-resistant and wear-resistant materials, allowing for multi-hole injection with a spray particle size below 10 μm. This improves the atomization effect of methanol spray at extremely low temperatures, solving the starting and ignition problems of methanol engines at extremely low temperatures. The multiple injection holes in the pre-combustion chamber 3 include multiple intake side holes facing the air inlet and multiple exhaust side holes facing away from the air inlet. The intake side holes are further aligned with the air inlet of the main combustion chamber 7, and their function is to quickly introduce air from the main combustion chamber 7 into the pre-combustion chamber 3 during the intake process. The exhaust side holes, on the other hand, discharge residual gas in the pre-combustion chamber 3 into the main combustion chamber 7 during the intake process, ensuring the intake effect within the pre-combustion chamber 3 and the concentration of the pre-combustion mixture at the moment of ignition.

[0045] Multiple air inlet side holes and multiple air outlet side holes are asymmetrically arranged with the central axis of the pre-combustion chamber 3 as the reference. The angle between the air outlet side hole and the central axis is greater than the angle between the air inlet side hole and the central axis, and the deviation of the angle is 3°-20°.

[0046] In this way, on the one hand, the ignition fuel spray is prevented from being directly injected into the main combustion chamber 7 through the nozzle, and on the other hand, the turbulence intensity in the pre-combustion chamber 3 can be improved through the asymmetric design to achieve better intake and exhaust effects. In addition, the asymmetric design structure can save layout space. Considering the turbulence on the exhaust side, and the fact that the exhaust side hole is away from the intake port and has a higher temperature, which is more likely to cause cylinder knock, the exhaust side hole is offset to a greater degree to reduce the risk of knock. However, the offset angle of the exhaust side hole should not be too large to avoid affecting the short range of the flame injected into the main combustion chamber 7 from the pre-combustion chamber 3, thus affecting ignition.

[0047] Preferably, the diameter of the injection hole is 1 mm to 2.5 mm; this ensures sufficient pressure difference and turbulence intensity in the pre-combustion chamber 3 and the main combustion chamber 7, and avoids blockage. The volume of the pre-combustion chamber 3 accounts for 1.5% to 3% of the volume of the main combustion chamber 7; this satisfies the ignition requirements of the main combustion chamber 7 without occupying too much space in the main combustion chamber 7 and affecting its work capacity.

[0048] The multi-electrode spark plug 1 has at least two electrodes, and furthermore, a heating device is provided on the multi-electrode spark plug 1. The control system adjusts the heating time of the heating device according to the monitored water temperature and ambient temperature to regulate the heating temperature of the multi-electrode spark plug and the pre-combustion chamber 3. In this way, the multi-electrode spark plug 1 and the pre-combustion chamber 3 can be heated in a low-temperature environment to ensure ignition effectiveness.

[0049] The control system's regulation of various combustion parameters can be achieved through the following process:

[0050] The engine speed and intake air volume are monitored, and based on the real-time speed and intake air volume, preset values ​​of each injection parameter are obtained according to the preset model; wherein, the preset model is configured to set the preset values ​​of the injection parameters based on the values ​​of engine speed and intake air volume.

[0051] The correction parameters are monitored, and the correction amount of each injection parameter is obtained based on the correction parameters and the corresponding correction model. The correction model is configured to set the correction amount of each injection parameter according to the correction parameters. The correction parameters include at least environmental parameters, namely at least one or any combination of the engine's water temperature, ambient temperature and ambient pressure. Furthermore, the correction parameters include the feedback parameters of the previous moment and the environmental parameters acquired in real time.

[0052] The actual values ​​of each injection parameter are adjusted according to preset values ​​and correction values, thereby adapting to different environmental conditions by correcting and adjusting each injection parameter.

[0053] That is, the control system acquires the engine's real-time speed and real-time intake air volume, as well as the engine's water temperature, ambient temperature, and ambient pressure. Based on the real-time speed and real-time intake air volume, it acquires the preset values ​​of the injection parameters according to the preset model. Based on the real-time acquired environmental parameters and the actual values ​​of each combustion parameter at the previous moment, it acquires the correction amount of the injection parameters at the current moment according to the correction model. Then, it adjusts the actual implementation values ​​of each injection parameter at the current moment according to the preset values ​​and correction amounts.

[0054] With this setup, the control system adaptively corrects and adjusts each injection parameter based on the actual parameters from the previous moment and the current environmental parameters, adapting to different operating conditions and ensuring successful ignition under various conditions. At the same time, it optimizes and controls the air-fuel ratio under each operating condition, making the air-fuel ratio the preset optimal air-fuel ratio.

[0055] In this application, the injection pressure of the ignition fuel is preset based on the engine speed and intake volume according to a preset model, and is adjusted based on real-time monitoring of water temperature, ambient temperature and ambient pressure.

[0056] When the control system detects that either the water temperature or the ambient temperature is lower than the preset low temperature value or the previous monitoring value, it increases the injection pressure of the ignition fuel based on the correction model, and decreases it if either is lower (i.e., when the ambient temperature is higher than the preset high temperature value or the previous monitoring value, it decreases the injection pressure of the ignition fuel based on the correction model); when the ambient pressure is lower than the preset low pressure value, it decreases the injection pressure of the ignition fuel based on the correction model.

[0057] It should be noted that reducing or increasing parameters based on the correction model means that the correction parameter values ​​in the correction model correspond to the fuel parameter values. The combustion parameter values ​​are adjusted accordingly based on the monitored correction parameter values. For example, the degree of fluctuation in the reduction or increase of combustion parameters depends on the degree of fluctuation of the correction parameters.

[0058] The injection pressure of the ignition fuel is typically preset to around 300 bar at normal engine speeds. Due to the small volume of the pre-combustion chamber 3 and the small injection volume of ignition fuel, it achieves good atomization under high-pressure injection, and adjusting the injection pressure has minimal impact on the atomization effect. At low temperatures, the evaporation and atomization effect of the ignition fuel deteriorates. Therefore, the injection pressure of the ignition fuel is increased at low water temperatures to ensure ignition performance during starting and warm-up. At high ambient temperatures and low ambient pressures, the fuel injection pressure is reduced to avoid excessive pressure leading to over-atomization of the fuel, excessive heat absorption, and impaired ignition.

[0059] The correction parameters for the amount of ignition fuel injection also include the proportion of ignition fuel in the total fuel injection amount. The total fuel injection amount refers to the sum of the main combustion fuel injection amount and the ignition fuel injection amount, which is preset according to the engine torque.

[0060] That is, the amount of ignition fuel injected is preset based on the engine speed and intake volume according to a preset model, and is adjusted based on real-time monitoring of water temperature, ambient temperature and ambient pressure, and is regulated according to its proportion in the total fuel injection amount.

[0061] When the control system detects that any one or any combination of water temperature, ambient temperature, and ambient pressure is lower than the preset low value or lower than the previous monitoring value (i.e., the current monitoring value is lower than the previous monitoring value or lower than the preset low threshold value, the same below), the injection amount of ignition fuel is increased based on the correction model, and the injection amount of ignition fuel is controlled not to exceed the preset maximum proportion in the total fuel injection amount.

[0062] In the preset model, the injection quantity of ignition fuel decreases as engine load increases; the total fuel injection quantity is converted using a torque / injection quantity model, which calibrates the correspondence between the total fuel injection quantity and torque. The proportion of ignition fuel injection quantity in the total fuel injection quantity must not exceed a preset maximum proportion. Simultaneously, adjustments are made to the ignition fuel injection quantity at low coolant temperatures, enriching the ignition fuel at low temperatures to ensure effective cold starts and combustion stability during warm-up.

[0063] The injection timing of the ignition fuel is based on engine speed, intake air volume, and the preset injection timing of the main fuel is preset according to a preset model. It has a fixed interval between the preset injection timing of the ignition fuel and the preset injection timing of the main fuel, and is adjusted based on real-time monitoring of water temperature, ambient temperature, and ambient pressure.

[0064] When the control system detects that any one or any combination of water temperature, ambient temperature, and ambient pressure is lower than the preset low value or lower than the monitoring value at the previous moment, it advances the injection time of the ignition fuel based on the correction model, and makes the injection time of the ignition fuel have a fixed interval with the preset injection time of the main combustion fuel.

[0065] That is, the ignition fuel injection time is based on the preset main combustion fuel injection time definition and maintains a fixed interval with the preset main combustion fuel injection time.

[0066] The ignition timing of the ignition fuel is preset based on the engine speed and intake air volume according to a preset model, and is adjusted based on real-time monitoring of water temperature, ambient temperature and ambient pressure. It is also adjusted according to the proportion of ignition fuel in the total fuel injection quantity, which is set according to the engine torque. When the control system detects that any one or any combination of water temperature, ambient temperature and ambient pressure is lower than the preset low value or the monitoring value of the previous moment, the ignition timing of the ignition fuel is advanced based on the correction model, and the ignition timing is delayed based on the correction model as the proportion of ignition fuel in the total fuel injection quantity increases.

[0067] The preset ignition timing defines the ignition timing of the multi-electrode spark plug 1 in the pre-combustion chamber 3 and the ignition timing of the main combustion chamber 7 to ensure the ignition and combustion effect of the engine. In addition, the correction of ignition timing and the ratio of ignition fuel to main combustion fuel is added. The higher the ratio of ignition fuel, the later the ignition timing. The correction of ignition timing is also added based on water temperature, ambient temperature and ambient pressure. By advancing the ignition, combustion under low temperature or low pressure conditions is accelerated, and the combustion performance during cold start and warm-up is improved.

[0068] The environmental pressure-based correction takes into account the decrease in in-cylinder intake air volume and oxygen content due to changes in atmospheric pressure in high-altitude environments. At this time, by appropriately reducing the injection pressure of the ignition fuel, advancing the ignition timing, and increasing the injection quantity of the ignition fuel, the fuel-air mixing effect can be improved, and the ignition performance under high-altitude environments can be improved.

[0069] The injection timing of the main combustion fuel is based on the engine speed and the intake air volume, which are preset according to the preset model. It is also adjusted based on the real-time monitoring of water temperature, ambient temperature and ambient pressure, and is further adjusted according to the actual injection timing of the ignition fuel in the previous moment, such as advancing or delaying, so that the injection timing of the main combustion fuel and the injection timing of the ignition fuel remain at a fixed duration.

[0070] When the control system detects that any one or any combination of water temperature, ambient temperature, and ambient pressure is lower than the preset low value or the monitoring value of the previous moment, it advances the injection time of the ignition fuel based on the correction model, and corrects the injection time of the main combustion fuel according to the actual injection time of the ignition fuel in the previous moment, for example, by advancing or delaying it, so that the injection time of the ignition fuel and the injection time of the main combustion fuel in the next moment remain at a fixed duration.

[0071] The preset injection timing of the main combustion fuel determines the timing of the main injection and pre-injection. The injection timing of the main combustion fuel is generally within 90 degrees before top dead center, and the injection duration is within 60 degrees (the angle refers to the crankshaft angle. When the crankshaft carries the piston to top dead center, it has a fixed angle. Within 90 degrees before top dead center means that the crankshaft angle is within 90 degrees before the angle corresponding to top dead center. The injection duration is within 60 degrees means that the injection lasts for at least the time it takes for the crankshaft angle to rotate 60 degrees). The injection duration and premixing period should be shortened as much as possible to reduce the risk of knocking.

[0072] At low water temperatures, the combustion rate slows down due to the low in-cylinder combustion temperature, resulting in a lower tendency for knocking. By adjusting the timing of the main fuel injection, the injection premixing time can be increased, improving the quality of the air-fuel mixture and optimizing the combustion process.

[0073] The correction based on ambient temperature mainly includes optimizing the injection advance angle (i.e., injection timing). This includes increasing the injection advance angle (i.e., advancing the injection timing) at low ambient temperatures to increase premixing time and improve the quality of the air-fuel mixture; and decreasing the injection advance angle (i.e., delaying the injection timing) at high ambient temperatures to reduce the increased tendency for knocking caused by excessive premixing.

[0074] As altitude increases, atmospheric pressure decreases, and the intake air volume decreases accordingly, slowing down the combustion process. At this time, the monitored low ambient pressure increases the injection advance angle to increase the injection premixing time and improve the quality of the air-fuel mixture.

[0075] The injection quantity of the main combustion fuel is preset based on the engine speed and intake volume according to a preset model, and is adjusted based on real-time monitoring of water temperature, ambient temperature and ambient pressure. It is also controlled according to its proportion in the total fuel injection quantity, which is set according to the engine torque.

[0076] When the control system detects that any one or any combination of water temperature, ambient temperature, and ambient pressure is lower than the preset low value or the monitoring value of the previous moment, it increases the injection quantity of the main combustion fuel based on the correction model, and controls the injection quantity of the main combustion fuel to be no less than the preset minimum proportion in the total fuel injection quantity.

[0077] The adjustment to increase the main combustion fuel injection quantity at low water temperatures is primarily achieved by modifying the torque / injection quantity model, thereby increasing the main combustion fuel injection quantity for the same torque requirement. Simultaneously, the torque adaptability to water temperature is implemented through the water temperature and torque model. For example, when the water temperature is too low, the torque increases, and the main combustion fuel injection quantity increases accordingly. Furthermore, at high altitudes and low ambient pressures, increasing the main combustion fuel injection quantity can appropriately enrich the fuel injection content, thereby improving combustion rate and enhancing power.

[0078] The injection pressure of the main combustion fuel is preset based on the engine speed and intake air volume according to a preset model, and is directly proportional to the engine torque. It is also adjusted based on real-time monitoring of water temperature, ambient temperature and ambient pressure.

[0079] When the control system detects that the water temperature is lower than the previous monitoring value or lower than the preset low value, it reduces the injection pressure of the main combustion fuel based on the correction model; when it detects that either the ambient temperature or the ambient pressure is lower than the preset low value or the previous monitoring value, it increases the injection pressure of the main combustion fuel based on the correction model.

[0080] The preset main fuel injection pressure is defined differently depending on the speed and intake volume. As the load increases, the preset main fuel injection pressure becomes higher and higher. Due to the high injection volume requirement, the injection rail pressure needs to be increased to reduce the injection duration, improve the spray effect, and prevent the spray from wetting the wall. As the speed increases, the preset injection rail pressure shows a characteristic of first rising and then falling. The rail pressure is the highest when the torque is the highest, in order to ensure power output, shorten the injection and combustion duration, and improve combustion.

[0081] Under low-pressure conditions, the injection pressure of the main combustion fuel increases.

[0082] At low water temperatures, the methanol evaporation and atomization effect deteriorates, but the main combustion fuel injection pressure is itself high, which can achieve a good atomization effect. However, methanol evaporation and atomization will absorb a large amount of heat in the cylinder, causing the cylinder temperature to be too low, which will affect combustion. In order to improve the effect of excessively good atomization at low temperatures that leads to excessively low cylinder temperature, the injection pressure of the main combustion fuel is reduced at low water temperatures.

[0083] That is, the combustion parameters are modified based on environmental factors to optimize ignition and combustion performance.

[0084] For ignition fuel, temperature-based corrections include increasing injection pressure, advancing injection, advancing ignition, and increasing injection quantity at low water temperatures; ambient temperature-based corrections include increasing injection pressure, increasing injection quantity, advancing injection, and advancing ignition at low ambient temperatures; and ambient pressure-based corrections include reducing ignition fuel injection pressure, advancing ignition time, and increasing ignition fuel injection quantity at low pressure.

[0085] For the main combustion fuel, temperature-based corrections include reducing the injection pressure, advancing the injection timing, and increasing the injection quantity at low water temperatures; ambient temperature-based corrections include increasing the injection pressure, increasing the injection quantity, advancing the injection, and advancing the ignition at low ambient temperatures; and ambient pressure-based corrections include increasing the injection pressure, advancing the ignition timing, and increasing the injection quantity of the main combustion fuel at low pressure environments.

[0086] The control system also uses the actual values ​​of each combustion parameter from the previous moment to correct the injection parameters at the current moment by modifying the model accordingly; that is, it corrects the actual values ​​of each combustion parameter at the current moment based on the feedback of each combustion parameter from the previous moment.

[0087] The control system also adjusts various combustion parameters based on the oxygen content in the exhaust pipe monitored by the oxygen sensor, ensuring that the air-fuel ratio is at the preset optimal air-fuel ratio. The preset optimal air-fuel ratio is the optimal air-fuel ratio set in the preset model based on the operating condition parameters.

[0088] This application also provides a vehicle, including a body and a methanol lean engine disposed on the body, the methanol lean engine being provided with an ignition system as described in the above embodiments.

[0089] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0090] The components and devices described in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the accompanying drawings. As those skilled in the art will recognize, these components and devices can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the words “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0091] It should also be noted that in the apparatus and equipment of this application, the components can be disassembled and / or reassembled. These disassemblies and / or reassemblies should be considered as equivalent solutions of this application.

[0092] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0093] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

[0094] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications or equivalent substitutions made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An ignition system for a methanol lean-burn engine, comprising an ignition device and a control system; The ignition device includes a main combustion chamber and a pre-combustion chamber. The main combustion chamber is equipped with an air inlet for introducing air into the chamber and a main injector for injecting methanol. The pre-combustion chamber is equipped with an ignition injector, a multi-electrode spark plug, and multiple injection holes connected to the main combustion chamber. in, Air entering the main combustion chamber enters the pre-combustion chamber through the injection holes and mixes with the ignition fuel injected by the ignition injector to form an ignition mixture. The ignition mixture is ignited by the multi-electrode spark plug, and the resulting flame is injected into the main combustion chamber through multiple injection holes, igniting the main combustion mixture formed by the air in the main combustion chamber and the methanol injected by the main injector. The control system is configured to monitor the engine speed, intake air volume and environmental parameters in real time to adjust the injection pressure, injection quantity, injection timing and ignition timing of the main combustion fuel and the pilot fuel in real time, so as to achieve stable ignition under different operating conditions and adjust the air-fuel ratio under each operating condition. The environmental parameters include at least one or any combination of the engine's water temperature, ambient temperature, and ambient pressure.

2. The ignition system of the methanol-lean engine as described in claim 1, wherein, The control system is configured to perform the following operations: Monitor engine speed and intake air volume, and obtain preset values ​​for each injection parameter based on real-time speed and intake air volume and corresponding preset models; Monitor correction parameters and obtain correction amounts for each injection parameter based on the correction parameters and the corresponding correction model, wherein the correction parameters include the environmental parameters acquired in real time; The actual values ​​of each injection parameter are adjusted according to the preset value and the correction amount, thereby adapting to different environmental conditions by correcting and adjusting each injection parameter.

3. The ignition system of the methanol-lean engine as described in claim 1 or 2, wherein, When the control system detects that either the water temperature or the ambient temperature is lower than a preset low temperature value or the previous monitoring value, it increases the injection pressure of the ignition fuel based on the correction model; when the ambient pressure is detected to be lower than a preset low pressure value, it decreases the injection pressure of the ignition fuel based on the correction model.

4. The ignition system of the methanol-lean engine as described in claim 1 or 2, wherein, When the control system detects that any one or any combination of water temperature, ambient temperature, and ambient pressure is lower than a preset low value or lower than the previous monitoring value, it increases the injection amount of the ignition fuel based on the correction model, and controls the injection amount of the ignition fuel to not exceed the preset maximum proportion in the total fuel injection amount.

5. The ignition system of the methanol-lean engine as described in claim 1 or 2, wherein, When the control system detects that any one or any combination of water temperature, ambient temperature, and ambient pressure is lower than a preset low value or lower than the previous monitoring value, it advances the injection time of the ignition fuel based on the correction model, and makes the injection time of the ignition fuel have a fixed interval with the preset injection time of the main combustion fuel.

6. The ignition system of the methanol-lean engine as described in claim 1 or 2, wherein, The correction parameter for the ignition timing of the ignition fuel also includes the proportion of the ignition fuel in the total fuel injection quantity, which is set according to the engine torque. When the control system detects that any one or any combination of water temperature, ambient temperature, and ambient pressure is lower than a preset low value or lower than the monitoring value at the previous moment, the ignition time of the ignition fuel is advanced based on the correction model, and the ignition time is delayed based on the correction model as the proportion of the ignition fuel in the total fuel injection increases.

7. The ignition system of the methanol lean-burn engine as described in claim 1, 2, or 5, wherein, When the control system detects that any one or any combination of water temperature, ambient temperature, and ambient pressure is lower than a preset low value, it advances the injection time of the ignition fuel based on the correction model, and corrects the injection time of the main combustion fuel according to the actual injection time of the ignition fuel at the previous moment.

8. The ignition system of the methanol lean-burn engine as described in claim 1 or 2, wherein, When the control system detects that any one or any combination of water temperature, ambient temperature, and ambient pressure is lower than a preset low value, it increases the injection amount of the main combustion fuel based on the correction model, and controls the injection amount of the main combustion fuel to be no less than a preset minimum proportion in the total fuel injection amount.

9. The ignition system of the methanol-lean engine as described in claim 1 or 2, wherein, The injection pressure of the main combustion fuel is directly proportional to the engine torque; and when the control system detects that the water temperature is lower than the previous monitoring value or lower than the preset low value, it reduces the injection pressure of the main combustion fuel based on the correction model; when either the ambient temperature or the ambient pressure is lower than the preset low value or lower than the previous monitoring value, it increases the injection pressure of the main combustion fuel based on the correction model.

10. The ignition system of the methanol lean-burn engine as described in any one of claims 1 to 9, wherein, The main injector is disposed in the intake manifold or offset on the cylinder head at the intake port, the pre-combustion chamber is located at the center of the cylinder head, and the plurality of injection holes include a plurality of intake side holes facing the intake port and a plurality of exhaust side holes facing away from the intake port. The plurality of air inlet side holes and the plurality of air outlet side holes are asymmetrically arranged with the central axis of the pre-combustion chamber as a reference. The angle between the plurality of air outlet side holes and the central axis is greater than the angle between the plurality of air inlet side holes and the central axis, and the deviation of the angle is 3°-20°.

11. The ignition system of the methanol lean-burn engine as described in any one of claims 1 to 10, wherein, The diameter of the injection hole is 1 mm to 2.5 mm; And / or, the volume of the pre-combustion chamber accounts for 1.5%-3% of the volume of the main combustion chamber; And / or, the multi-electrode spark plug has at least two electrodes, and the multi-electrode spark plug is provided with a heating device, and the control system adjusts the heating time of the heating device according to the monitored water temperature and ambient temperature, so as to regulate the heating temperature of the multi-electrode spark plug and the pre-combustion chamber.

12. A vehicle comprising a body and a methanol lean engine disposed on the body, the methanol lean engine being configured with an ignition system according to any one of claims 1-11.

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