Ignition system of methanol rarefied engine and vehicle

Abstract

The invention provides an ignition system of a methanol rarefied engine and a vehicle. The system comprises an ignition device and a control system. The ignition device comprises a main combustion chamber and a pre-combustion chamber; the main combustion chamber is provided with an air inlet for introducing air into the chamber and a main ejector for ejecting methanol; the pre-combustion chamber is provided with an ignition injector, a multi-electrode spark plug and a plurality of injection holes communicated with the main combustion chamber; the control system is configured to regulate and control the injection pressure, the injection amount, the injection moment and the ignition moment of the main combustion fuel and the ignition fuel in real time by monitoring the rotating speed, the air inlet amount and the environmental parameters of the engine in real time, so that stable ignition under different working condition parameters is achieved, and the air-fuel ratio under various working conditions is regulated and controlled. By optimizing the ignition system, the engine can be stably ignited and efficiently combusted under different environment working conditions, so that the economic performance of the methanol rarefied engine is further improved on the basis of realizing stable ignition.

Description

Technical Field

[0001] The present application relates to the field of vehicle technology, and in particular to an ignition system of a lean methanol engine, and a vehicle comprising the engine and the ignition system thereof. Background Art

[0002] Lean Burn is an engine combustion technology that achieves efficient combustion by mixing less fuel with more air than conventional combustion. Specifically, a lean burn engine operates under very high air-fuel ratio conditions (i.e., the air contains relatively less fuel). This technology has the advantages of low fuel consumption, low emissions, and low required cooling heat, but it has technical challenges such as ignition difficulties and the need to improve combustion stability.

[0003] If the technology is to be applied to methanol engines, methanol has a large latent heat of vaporization, which will absorb a large amount of heat in the process of forming methanol vapor, causing the temperature in the cylinder to drop sharply. In addition, methanol has a high auto-ignition temperature, so ignition is relatively difficult in an equivalent environment. For methanol lean-burn engines, the airflow is not stable enough, the cylinder pressure is high, and the oil and gas concentration is thin in the ultra-thin air environment in the cylinder, making ignition even more difficult. Therefore, how to improve the ignition stability of methanol lean-burn engines is a necessary issue faced by applying lean-burn technology to methanol engines. Summary of the invention

[0004] In view of this, the present application is committed to providing an ignition system for a methanol lean fuel engine, which optimizes the ignition system to enable the engine to have stable ignition and efficient combustion under different environmental conditions, and further improves the economic performance of the methanol lean fuel engine on the basis of achieving stable ignition.

[0005] The present application provides an ignition system for a lean methanol engine, comprising an ignition device and a control system; the ignition device comprises a main combustion chamber and a pre-combustion chamber, the main combustion chamber is provided with an air inlet for introducing air into the chamber and a main injector for injecting methanol; the pre-combustion chamber is provided with a pilot injector, a multi-electrode spark plug, and a plurality of injection holes connected to the main combustion chamber;

[0006] The air entering the main combustion chamber enters the pre-combustion chamber through the injection holes and mixes with the pilot fuel injected by the pilot injector to form a pilot mixture. The pilot mixture is ignited by the multi-electrode spark plug to generate a flame that is injected into the main combustion chamber from the plurality of injection holes and ignites the main combustion chamber and the main combustion mixture formed by the air in the main combustion chamber and the methanol injected by the main injector.

[0007] The control system is configured to monitor the engine speed, intake volume and environmental parameters in real time to adjust the injection pressure, injection volume, injection timing and ignition timing of the main fuel and the pilot fuel in real time, so as to achieve stable ignition under different operating parameters and adjust the air-fuel ratio under each operating condition;

[0008] The environmental parameters include at least one or any combination of the water temperature, ambient temperature and ambient pressure of the engine.

[0009] In a possible implementation, the control system is configured to perform the following operations:

[0010] Monitor the engine speed and intake air volume, and obtain preset values ​​of various injection parameters corresponding to the preset model based on the real-time speed and intake air volume;

[0011] Monitoring correction parameters, and obtaining correction amounts of each of the injection parameters based on the correction parameters and corresponding correction models, wherein the correction parameters include the environmental parameters obtained in real time;

[0012] The actual implementation value of each of the injection parameters is regulated according to the preset value and the correction amount, so as to adapt to different environmental conditions by correcting and adjusting each of the injection parameters.

[0013] In one possible implementation, when the control system monitors that either the water temperature or the ambient temperature is lower than a preset low temperature value or a monitored value at a previous moment, the injection pressure of the pilot fuel is increased based on a correction model; when the ambient pressure is monitored to be lower than a preset low pressure value, the injection pressure of the pilot fuel is reduced based on the correction model.

[0014] In one possible implementation, when the control system monitors that any one or any combination of the water temperature, ambient temperature, and ambient pressure is lower than a preset low value or lower than the value monitored at the previous moment, the injection amount of the pilot fuel is increased based on the correction model, and the injection amount of the pilot fuel is controlled not to exceed a preset maximum proportion of the total fuel injection amount.

[0015] In one possible implementation, when the control system monitors that any one or any combination of the water temperature, ambient temperature, and ambient pressure is lower than a preset low value or lower than the value monitored at the previous moment, the injection timing of the pilot fuel is advanced based on a correction model, and the injection timing of the pilot fuel has a fixed interval length with the preset injection timing of the main combustion fuel.

[0016] In a possible implementation manner, the correction parameter of the ignition timing of the pilot fuel further includes the proportion of the pilot fuel in the total fuel injection amount, and the total fuel injection amount is set according to the engine torque;

[0017] When the control system monitors that any one or any combination of the water temperature, ambient temperature, and ambient pressure is lower than a preset low value or lower than the monitored value at the previous moment, the ignition timing of the pilot fuel is advanced based on the correction model, and as the proportion of the pilot fuel in the total fuel injection amount increases, the ignition timing is delayed based on the correction model.

[0018] In one possible implementation, when the control system monitors that any one or any combination of the water temperature, ambient temperature, and ambient pressure is lower than a preset low value, the injection timing of the pilot fuel is advanced based on a correction model, and the injection timing of the main combustion fuel is corrected according to the actual injection timing of the pilot fuel at the previous moment.

[0019] In one possible implementation, when the control system monitors that any one or any combination of the water temperature, ambient temperature, and ambient pressure is lower than a preset low temperature value, the injection amount of the main fuel is increased based on a correction model, and the injection amount of the main fuel is controlled to be no lower than a preset minimum proportion of the total fuel injection amount.

[0020] In one possible implementation, the injection pressure of the main fuel is directly proportional to the engine torque; and when the control system detects that the water temperature is lower than the monitoring value at the previous moment or lower than a preset low value, the injection pressure of the main fuel is reduced based on the correction model; when it is detected that either the ambient temperature or the ambient pressure is lower than the preset low value or lower than the monitoring value at the previous moment, the injection pressure of the main fuel is increased based on the correction model.

[0021] In a possible implementation manner, the main injector is arranged in the intake passage or offset on the cylinder head and located at the intake port, the pre-combustion chamber is located at the center of the cylinder head, and the multiple injection holes include multiple intake side holes facing the intake port and multiple outlet side holes facing away from the intake port;

[0022] The multiple air inlet side holes and the multiple air outlet side holes are asymmetrically arranged about the central axis of the pre-combustion chamber, and the angle between the multiple air outlet side holes and the central axis is greater than the angle between the multiple air inlet side holes and the central axis, and the angle deviation range is 3°-20°.

[0023] In a possible implementation, the diameter of the injection hole is 1 mm-2.5 mm.

[0024] And / or, the volume of the pre-combustion chamber accounts for 1.5%-3% of the volume of the main combustion chamber

[0025] And / or, the multi-electrode spark plug has at least two electrodes, and a heating device is provided on the multi-electrode spark plug, and the control system adjusts the heating time of the heating device according to the monitored water temperature and ambient temperature to adjust the heating temperature of the multi-electrode spark plug and the pre-combustion chamber.

[0026] The present application also provides a vehicle, comprising a vehicle body and a methanol lean engine arranged on the vehicle body, wherein the methanol lean engine is configured with an ignition system as described in any one of the above items.

[0027] The ignition system of the methanol lean engine provided by the present application can efficiently pre-combust in a small-volume pre-combustion chamber by setting a pre-combustion chamber and a multi-electrode spark plug, and then spray the flame through multiple injection holes to the main combustion chamber by high pressure, so as to ignite the main combustion mixture in the main combustion chamber at multiple points, efficiently and evenly, and can effectively improve the ignition effectiveness; at the same time, the control system adjusts the injection amount, injection pressure, injection time and ignition time of the ignition fuel and the main combustion fuel in real time through real-time monitoring of engine parameters and environmental parameters, so that the fuel is fully mixed and then burned efficiently, so as to meet the stable ignition and efficient combustion of the lean oil and gas in the cylinder under different environmental conditions, especially in adverse environments such as low temperature and low pressure, and to have the optimal air-fuel ratio under each operating condition, thereby further improving the economic performance of the methanol lean engine on the basis of achieving stable ignition. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The figure shows a first structural schematic diagram of an ignition device for a lean methanol engine in an embodiment of the present application;

[0029] Figure 2 The figure shows a second structural schematic diagram of the ignition device of the lean methanol engine in the embodiment of the present application;

[0030] Figure 3 Shown is a schematic diagram of the control system regulating combustion parameters in an embodiment of the present application.

[0031] Figure 1-Figure 2 middle:

[0032] 1. Multi-electrode spark plug; 2. Pilot injector; 3. Pre-combustion chamber; 4. Throttle valve; 5. Main injector; 6. Supply common rail pipe; 7. Main combustion chamber; 8. Intake duct. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0034] Please refer to the attached Figure 1-Figure 3 An embodiment of the present application provides an ignition system for a methanol lean engine, including an ignition device and a control system, wherein the control system is used to regulate the ignition device and implement a control method for the ignition device; this is equivalent to the present application providing 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 provided with an air inlet and a main injector 5. The air inlet is formed by an air inlet duct 8 connected to the main combustion chamber 7. The air inlet duct 8 is provided with a throttle valve 4. Air is injected into the main combustion chamber 7 through the air inlet duct 8 and the air inlet. The main injector 5 is used to inject the main combustion fuel, namely methanol, into the main combustion chamber 7. The pre-combustion chamber 3 is provided with a pilot injector 2 for injecting the pilot fuel and a multi-electrode spark plug 1 for ignition, and the pre-combustion chamber 3 is provided with a plurality of injection holes connected to the main combustion chamber 7. The pilot fuel can be methanol or a flammable material such as gasoline. When the pilot fuel is also methanol, the pilot injector 2 and the main injector 5 can be connected to the same supply common rail pipe 6.

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

[0037] Among them, the air entering the main combustion chamber 7 enters the pre-combustion chamber 3 through the injection hole and mixes with the ignition fuel injected by the pilot injector 2 to form an ignition mixture. The ignition mixture is ignited by the multi-electrode spark plug 1 to generate a flame, and the flame is sprayed into the main combustion chamber 7 from multiple injection holes to form a multi-point jet ignition, and ignites the main combustion mixture formed by air and methanol in the main combustion chamber 7. In this way, the ignition is now carried out in the small pre-combustion chamber 3, and the ignition is carried out through the multi-electrode spark plug 1, which can eliminate unfavorable factors such as thin oil and gas and large latent heat of methanol that are not conducive to ignition, and ensure successful ignition. The flame generated after ignition is driven by the high pressure in the pre-combustion chamber 3, and is sprayed into the main combustion chamber 7 from multiple injection holes, and multiple points are evenly ignited in multiple areas in the main combustion chamber 7, effectively ensuring the ignition success rate and avoiding ignition failure.

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

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

[0040] In this way, the control system adjusts the injection parameters and ignition timing such as fuel injection timing, injection amount, injection pressure, etc. in real time according to the parameters of the engine and the parameters of the engine environment, which can ensure that the fuel is fully premixed before ignition, and can also ensure excellent ignition timing. It can also ensure successful ignition under various operating conditions, especially under adverse conditions such as low temperature and low pressure. At the same time, it can also ensure a high air-fuel ratio by adjusting the fuel injection parameters and ignition conditions to avoid excessive fuel injection and loss. On the basis of ensuring successful ignition under various operating conditions, the air-fuel ratio is adjusted within the preset optimal range to avoid reducing the air-fuel ratio and affecting the economy of the lean engine.

[0041] It can be seen that the ignition system of the methanol lean engine provided in the present application, by setting up a pre-combustion chamber 3 and a multi-electrode spark plug 1, can efficiently ignite the pilot fuel in the small-volume pre-combustion chamber 3, and then spray the flame through multiple injection holes to the main combustion chamber 7 by high pressure, so as to ignite the main combustion mixture in the main combustion chamber 7 at multiple points, efficiently and evenly, and can effectively improve the ignition effectiveness; at the same time, the control system adjusts the injection amount, injection pressure, injection time and ignition time of the pilot fuel and the main combustion fuel in real time through real-time monitoring of engine parameters and environmental parameters, so that the fuel is fully mixed before ignition and efficient combustion, so as to meet the stable ignition and efficient combustion of the lean oil and gas in the cylinder under different environmental conditions, especially under adverse environments such as low temperature and low pressure, and ensure that each operating condition has the optimal ignition time and air-fuel ratio, thereby further improving the economic performance of the methanol lean engine on the basis of achieving stable ignition.

[0042] like Figure 1 As shown, the main combustion chamber 7 is a roof-shaped structure, that is, the cylinder head is a roof-shaped structure. The main injector 5 is offset on the cylinder head, for example, the nozzle is located at the intake port; or Figure 2 As shown, the main injector 5 is arranged on the intake passage 8, the nozzle is located in the intake passage 8, and the throttle valve 4 is located at the front end of the intake passage 8. In this way, the mixing time of methanol and air can be increased, and the mixing uniformity of the two can be improved.

[0043] The pre-combustion chamber 3 is located at the center of the cylinder head, that is, it is centrally arranged in the cylinder body. Therefore, when the flame is sprayed, it can spray from the center to multiple points around, ignite the main combustion mixture evenly at multiple points, and improve the ignition speed and effectiveness.

[0044] The main injector 5 and the pilot injector 2 are both corrosion-resistant direct injection devices with an injection pressure range of 200-800 bar, which can realize the injection of methanol or other pilot fuels in the pre-combustion chamber 3 and realize good oil-gas atomization in the pre-combustion chamber 3. The injector is made of corrosion-resistant and wear-resistant materials, can be multi-hole injection, and the spray particle size can reach less than 10um, which can improve the methanol spray at extremely low temperatures and solve the problems of methanol engine starting and ignition at extremely low temperatures. In addition, the multiple injection holes of 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 hole is more toward the air inlet of the main combustion chamber 7, and its function is to quickly introduce the air in the main combustion chamber 7 into the pre-combustion chamber 3 during the intake process, while the exhaust side hole is used to discharge the residual gas in the pre-combustion chamber 3 to the main combustion chamber 7 during the intake process, so as to ensure the intake effect in the pre-combustion chamber 3 and the concentration of the pre-combustion mixture at the ignition time.

[0045] 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 3, the angle between the air outlet side holes and the central axis is greater than the angle between the air inlet side holes and the central axis, and the angle deviation range is 3°-20°.

[0046] In this way, on the one hand, the ignition fuel spray is prevented from being directly sprayed into the main combustion chamber 7 through the spray hole, 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; and the outlet side hole is more offset, mainly considering the turbulence on the outlet side, and the outlet side hole is away from the air inlet, the temperature is higher, and it is more likely to cause cylinder knock. The large degree of offset of the outlet side hole can reduce the risk of knock; but the outlet side hole deviation angle should not be too large, so as to avoid affecting the flame in the pre-combustion chamber 3 when it is sprayed into the main combustion chamber 7, resulting in a short range and affecting ignition.

[0047] Preferably, the diameter of the injection hole is 1 mm-2.5 mm; in this way, it can ensure that there is sufficient pressure difference and turbulence intensity in the pre-combustion chamber 3 and the main combustion chamber 7, and avoid blockage. The volume of the pre-combustion chamber 3 accounts for 1.5%-3% of the volume of the main combustion chamber 7; in this way, it can meet the ignition requirements of the main combustion chamber 7 without occupying too much space in the main combustion chamber 7 to affect the working capacity of the main combustion chamber 7.

[0048] The multi-electrode spark plug 1 has at least two electrodes, and further, a heating device is provided on the multi-electrode spark plug 1, and the control system adjusts the heating time of the heating device according to the monitored water temperature and ambient temperature to adjust 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 the ignition effectiveness.

[0049] The control system regulates various combustion parameters in the following process:

[0050] Monitor the speed and intake volume of the engine, and based on the real-time speed and intake volume, obtain preset values ​​of various injection parameters corresponding to the preset model; wherein the preset model is configured to set the preset values ​​of the injection parameters according to the values ​​of the speed and intake volume of the engine;

[0051] Monitoring correction parameters, and obtaining correction amounts of various injection parameters based on the correction parameters and corresponding correction models; wherein the correction model is configured to set correction amounts of various injection parameters based on the correction parameters, and the correction parameters at least include environmental parameters, i.e., at least one or any combination of water temperature, ambient temperature, and ambient pressure of the engine, and further, the correction parameters include feedback parameters at a previous moment and environmental parameters obtained in real time;

[0052] The actual implementation value of each injection parameter is adjusted according to the preset value and correction amount.

[0053] That is, the control system obtains the real-time speed and real-time intake volume of the engine, the water temperature, ambient temperature and ambient pressure of the engine, obtains the preset value of the injection parameter according to the real-time speed and real-time intake volume, and obtains the correction amount of the injection parameter at the current moment according to the corresponding correction model based on the environmental parameters obtained in real time and the actual values ​​of each combustion parameter at the previous moment; and then adjusts the actual implementation value of each injection parameter at the current moment according to the preset value and the correction amount.

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

[0055] In the present application, the injection pressure of the pilot fuel is preset according to a preset model based on the engine speed and the intake volume, and is corrected and adjusted based on the real-time monitored 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 monitoring value at the previous moment, the injection pressure of the pilot fuel is increased based on the correction model, otherwise it is reduced (that is, when the ambient temperature is detected to be higher than the preset high temperature value or the monitoring value at the previous moment, the injection pressure of the pilot fuel is reduced based on the correction model); when the ambient pressure is detected to be lower than the preset low temperature value, the injection pressure of the pilot fuel is reduced based on the correction model.

[0057] It should be noted that reducing and increasing parameters based on the correction model means that the correction parameter value in the correction model has a corresponding relationship with the fuel parameter value, and the combustion parameter value is adjusted accordingly according to the monitored correction parameter value. For example, the degree of fluctuation of the reduction and increase of the combustion parameter depends on the degree of fluctuation of the correction parameter.

[0058] The injection pressure of the pilot fuel is generally preset to about 300 bar at normal engine speed. Because the pre-combustion chamber 3 is small in volume and the injection amount of the pilot fuel is small, it has a good spray effect under high-pressure injection, and the injection pressure has little effect on the spray effect. The evaporation atomization effect of the pilot fuel deteriorates at low temperatures. The injection pressure of the pilot fuel at low water temperatures is corrected to ensure the ignition effect during starting and warming up; under high ambient temperature and low ambient pressure, the injection pressure of the fuel is reduced to avoid excessive pressure, which leads to excessive atomization of the fuel and excessive heat absorption, affecting ignition.

[0059] The correction parameter of the injection amount of the pilot fuel also includes the proportion of the pilot fuel in the total fuel injection amount. The total fuel injection amount refers to the sum of the main fuel injection amount and the pilot fuel injection amount. The total fuel injection amount is pre-set according to the engine torque.

[0060] That is, the injection amount of the pilot fuel is preset according to a preset model based on the engine speed and the intake volume, and is corrected and adjusted based on the real-time monitored 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 the water temperature, ambient temperature, and ambient pressure is lower than the preset low value or lower than the monitoring value at the previous moment (that is, the current monitoring value is lower than the monitoring value at the previous moment or lower than the preset low critical value, the same below), the injection amount of the pilot fuel is increased based on the correction model, and the injection amount of the pilot fuel is controlled not to exceed the preset maximum proportion of the total fuel injection amount.

[0062] In the preset model, the injection amount of the pilot fuel decreases as the engine load increases; the total fuel injection amount is converted through the torque / injection amount model, which calibrates the correspondence between the total fuel injection amount and the torque. The maximum proportion of the pilot fuel injection amount in the total fuel injection amount shall not exceed the preset maximum proportion. At the same time, the correction adjustment of the pilot fuel injection amount at low water temperature is increased, and the cold start effect and combustion stability during the warm-up process are ensured by enriching the pilot fuel at low temperature.

[0063] The injection timing of the pilot fuel is preset based on the engine speed, intake volume and the preset injection timing of the main fuel according to a preset model, has a fixed interval length with the preset injection timing of the main fuel, and is corrected and adjusted based on real-time monitored water temperature, ambient temperature and ambient pressure.

[0064] When the control system detects that any one or any combination of the water temperature, ambient temperature, and ambient pressure is lower than a preset low value or lower than the monitored value at the previous moment, the injection timing of the pilot fuel is advanced based on the correction model, and the injection timing of the pilot fuel is made to have a fixed interval length with the preset main fuel injection timing.

[0065] That is, the preset pilot fuel injection timing is defined based on the set main fuel injection timing, and is kept at a fixed interval from the set main fuel injection timing.

[0066] The ignition timing of the pilot fuel is preset according to a preset model based on the engine speed and the intake air volume, and is corrected and adjusted based on the real-time monitored water temperature, ambient temperature and ambient pressure, and is regulated according to the proportion of the pilot fuel in the total fuel injection volume, and the total fuel injection volume is set according to the engine torque;

[0067] When the control system detects that any one or any combination of the water temperature, ambient temperature, and ambient pressure is lower than the preset low value or the monitored value at the previous moment, the ignition timing of the pilot fuel is advanced based on the correction model, and the ignition timing is delayed based on the correction model as the proportion of the pilot fuel in the total fuel injection amount increases.

[0068] The preset ignition timing defines the ignition timing of the multi-electrode spark plug 1 in the pre-combustion chamber 3 and the pilot ignition timing of the main combustion chamber 7 to ensure the engine ignition and combustion effect; in addition, the correction of the ignition timing and the ratio of pilot fuel to main combustion fuel is added. The higher the ratio of pilot fuel, the later the ignition timing; and the correction of the ignition timing is increased based on the water temperature, ambient temperature and ambient pressure. By igniting in advance to accelerate combustion under low temperature or low pressure conditions, the combustion performance during cold start and warm-up is improved.

[0069] The correction based on ambient pressure takes into account the decrease in the intake volume and oxygen content in the cylinder due to changes in atmospheric pressure in plateau environments. At this time, by appropriately reducing the injection pressure of the pilot fuel, advancing the ignition timing, increasing the injection amount of the pilot fuel, etc., the oil-gas mixing effect can be improved and the ignition performance in plateau environments can be improved.

[0070] The injection timing of the main fuel is preset according to a preset model based on the engine speed and the intake volume, and is corrected and adjusted based on the real-time monitored water temperature, ambient temperature and ambient pressure, and is corrected according to the actual injection timing of the pilot fuel at the previous moment, for example, advanced or retarded, so that the injection timing of the main fuel and the injection timing of the pilot fuel remain at a fixed duration.

[0071] When the control system detects that any one or any combination of the water temperature, ambient temperature, and ambient pressure is lower than the preset low value or the monitored value at the previous moment, the injection timing of the pilot fuel is advanced based on the correction model, and the injection timing of the main fuel is corrected according to the actual injection timing of the pilot fuel at the previous moment, for example, advanced or retarded, so that the injection timing of the pilot fuel and the injection timing of the main fuel at the next moment maintain a fixed duration.

[0072] The preset main fuel injection timing determines the main injection and pre-injection timing. The injection timing of the main 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. The crankshaft has a fixed angle when it reaches the top dead center with the piston. Within 90 degrees before top dead center means that the crankshaft angle is within 90 degrees before the angle corresponding to the top dead center. The injection duration within 60 degrees means that the injection lasts for no less than the time when the crankshaft angle rotates 60 degrees). Try to shorten the injection duration and premixing period to reduce the risk of knock.

[0073] Under low water temperature, the combustion temperature in the cylinder is low, the combustion rate slows down, and the knock tendency is low. Through correction, the injection timing of the main fuel is advanced, which can increase the injection premixing time, improve the quality of the mixture, and optimize the combustion process.

[0074] The correction based on ambient temperature mainly includes optimization of the injection advance angle (i.e. injection timing), including increasing the injection advance angle (i.e. advancing the injection timing) at low ambient temperature to increase the premixing time and improve the quality of the mixture; reducing the injection advance angle (i.e. delaying the injection timing) at high ambient temperature to reduce the increased knock tendency caused by excessive premixing.

[0075] As the altitude continues to rise, the atmospheric pressure continues to decrease, the intake volume decreases accordingly, and the combustion process slows down. At this time, the monitored ambient low pressure increases the injection advance angle to increase the injection premixing time and improve the quality of the mixture.

[0076] The injection amount of the main fuel is preset according to a preset model based on the engine speed and the intake volume, and is corrected and adjusted based on the real-time monitored water temperature, ambient temperature and ambient pressure, and is regulated according to its proportion in the total fuel injection amount, and the total fuel injection amount is set according to the engine torque.

[0077] When the control system detects that any one or any combination of the water temperature, ambient temperature, and ambient pressure is lower than the preset low value or the monitored value at the previous moment, the injection amount of the main fuel is increased based on the correction model, and the injection amount of the main fuel is controlled to be no lower than the preset minimum proportion of the total fuel injection amount.

[0078] The correction of the main fuel injection amount under low water temperature is mainly achieved by correcting the torque / injection amount model, increasing the main fuel injection amount under the same torque demand; at the same time, the torque changes adaptively with the water temperature, which is achieved through the water temperature and torque model. For example, when the water temperature is too low, the torque increases and the main fuel injection amount increases. At the same time, at high altitudes and low ambient pressures, by increasing the main fuel injection amount, the injection content can be appropriately enriched to improve the combustion rate and enhance the power.

[0079] The injection pressure of the main fuel is preset according to a preset model based on the engine speed and the intake volume, and is directly proportional to the engine torque, and is corrected and adjusted based on the real-time monitored water temperature, ambient temperature and ambient pressure.

[0080] When the control system detects that the water temperature is lower than the monitoring value at the previous moment or lower than the preset low value, the injection pressure of the main fuel is reduced based on the correction model; when the control system detects that either the ambient temperature or the ambient pressure is lower than the preset low value or the monitoring value at the previous moment, the injection pressure of the main fuel is increased based on the correction model.

[0081] The preset main fuel injection pressure is defined differently at different speeds and intake volumes. As the load continues to increase, the preset main fuel injection pressure becomes higher and higher. Due to the high injection volume demand, 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 rises first and then falls. The rail pressure is highest when the torque is highest to ensure power output, shorten the injection and combustion duration, and improve combustion.

[0082] Under low pressure conditions, the main fuel injection pressure is increased.

[0083] Under low water temperature, the evaporation atomization effect of methanol becomes worse, but the injection pressure of the main fuel itself is at high pressure, which can achieve a better atomization effect. The evaporation atomization of methanol will absorb a large amount of heat in the cylinder, causing the temperature in the cylinder to be too low, affecting combustion. In order to improve the low temperature effect in the cylinder caused by excessive atomization at low temperature, the injection pressure of the main fuel is reduced under low water temperature.

[0084] That is, various combustion parameters are modified based on environmental factors to optimize ignition and combustion performance.

[0085] For the pilot fuel, corrections based on water temperature include increasing the injection pressure, advancing the injection, advancing the ignition, and increasing the injection amount at low water temperature; corrections based on ambient temperature include increasing the injection pressure, increasing the injection amount, advancing the injection, and advancing the ignition at low ambient temperature; corrections based on ambient pressure include reducing the injection pressure of the pilot fuel, advancing the ignition timing, and increasing the injection amount of the pilot fuel under low pressure conditions.

[0086] For the main fuel, the correction based on water temperature includes, at low temperatures, reducing the injection pressure of the main fuel, advancing the injection timing and increasing the injection amount; the correction based on ambient temperature includes, at low ambient temperatures, increasing the injection pressure, increasing the injection amount, advancing the injection and igniting in advance; the correction based on ambient pressure includes, at low pressure environments, increasing the injection pressure of the main fuel, advancing the ignition timing and increasing the injection amount of the main fuel.

[0087] The control system will also obtain the correction amount of the injection parameter at the current moment according to the corresponding correction model based on the actual value of each combustion parameter at the previous moment; that is, based on the feedback of each combustion parameter at the previous moment, the actual value of each combustion parameter at the current moment is corrected.

[0088] The control system will also adjust various combustion parameters based on the oxygen sensor's monitoring of the oxygen content in the exhaust pipe, so that the air-fuel ratio is the preset optimal air-fuel ratio. The preset optimal air-fuel ratio is the optimal air-fuel ratio set in the preset model according to the operating condition parameters.

[0089] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.

[0090] The components and devices involved in this application are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the drawings. As will be appreciated by those skilled in the art, these components and devices can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open words, meaning "including but not limited to", and can be used interchangeably with them. The words "or" and "and" used here refer to the words "and / or" and can be used interchangeably with them, unless the context clearly indicates otherwise. The word "such as" used here refers to the phrase "such as but not limited to", and can be used interchangeably with it.

[0091] It should also be noted that in the device and apparatus of the present application, each component can be decomposed and / or reassembled, and such decomposition and / or reassembly should be regarded as an equivalent solution of the present application.

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

[0093] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

[0094] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An ignition system for a methanol lean engine, characterized in that: Includes ignition device and control system; The ignition device comprises a main combustion chamber and a pre-combustion chamber, wherein the main combustion chamber is provided with an air inlet for introducing air into the chamber and a main injector for injecting methanol; the pre-combustion chamber is provided with a pilot injector, a multi-electrode spark plug, and a plurality of injection holes communicating with the main combustion chamber; The air entering the main combustion chamber enters the pre-combustion chamber through the injection holes and mixes with the pilot fuel injected by the pilot injector to form a pilot mixture. The pilot mixture is ignited by the multi-electrode spark plug to generate a flame that is injected into the main combustion chamber from the plurality of injection holes and ignites the main combustion chamber and 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 volume and environmental parameters in real time to adjust the injection pressure, injection volume, injection timing and ignition timing of the main fuel and the pilot fuel in real time, so as to achieve stable ignition under different operating parameters and adjust the air-fuel ratio under each operating condition; The environmental parameters include at least one or any combination of the water temperature, ambient temperature and ambient pressure of the engine.

2. The ignition system of the lean methanol engine according to claim 1, characterized in that: The control system is configured to perform the following operations: Monitor the engine speed and intake air volume, and obtain preset values ​​of various injection parameters corresponding to the preset model based on the real-time speed and intake air volume; Monitoring correction parameters, and obtaining correction amounts of each of the injection parameters based on the correction parameters and corresponding correction models, wherein the correction parameters include the environmental parameters obtained in real time; The actual implementation value of each of the injection parameters is regulated according to the preset value and the correction amount, so as to adapt to different environmental conditions by correcting and adjusting each of the injection parameters.

3. The ignition system of the methanol lean engine according to claim 1, characterized in that: When the control system monitors that either the water temperature or the ambient temperature is lower than a preset low temperature value or the monitored value at the previous moment, the injection pressure of the pilot fuel is increased based on the correction model; when the monitored ambient pressure is lower than a preset low pressure value, the injection pressure of the pilot fuel is reduced based on the correction model.

4. The ignition system of the lean methanol engine according to claim 1, characterized in that: When the control system monitors that any one or any combination of the water temperature, ambient temperature, and ambient pressure is lower than a preset low value or lower than the value monitored at the previous moment, the injection amount of the pilot fuel is increased based on the correction model, and the injection amount of the pilot fuel is controlled not to exceed a preset maximum proportion of the total fuel injection amount.

5. The ignition system of the lean methanol engine according to claim 1, characterized in that: When the control system monitors that any one or any combination of the water temperature, ambient temperature, and ambient pressure is lower than a preset low value or lower than the value monitored at the previous moment, the injection timing of the pilot fuel is advanced based on the correction model, and the injection timing of the pilot fuel is made to have a fixed interval length with the preset injection timing of the main combustion fuel.

6. The ignition system of the lean methanol engine according to claim 1, characterized in that: The correction parameter of the ignition timing of the pilot fuel also includes the proportion of the pilot fuel in the total fuel injection amount, and the total fuel injection amount is set according to the engine torque; When the control system monitors that any one or any combination of the water temperature, ambient temperature, and ambient pressure is lower than a preset low value or lower than the monitored value at the previous moment, the ignition timing of the pilot fuel is advanced based on the correction model, and as the proportion of the pilot fuel in the total fuel injection amount increases, the ignition timing is delayed based on the correction model.

7. The ignition system of the methanol lean engine according to claim 1 or 5, characterized in that: When the control system detects that any one or any combination of the water temperature, ambient temperature, and ambient pressure is lower than a preset low value, the injection timing of the pilot fuel is advanced based on the correction model, and the injection timing of the main fuel is corrected according to the actual injection timing of the pilot fuel at the previous moment.

8. The ignition system of the lean methanol engine according to claim 1, characterized in that: When the control system monitors that any one or any combination of the water temperature, ambient temperature, and ambient pressure is lower than a preset low temperature value, the injection amount of the main fuel is increased based on the correction model, and the injection amount of the main fuel is controlled to be no lower than a preset minimum proportion of the total fuel injection amount.

9. The ignition system of the lean methanol engine as claimed in claim 4, characterized in that: The injection pressure of the main fuel is directly proportional to the engine torque; and when the control system detects that the water temperature is lower than the monitoring value at the previous moment or lower than the preset low value, the injection pressure of the main fuel is reduced based on the correction model; when it is detected that any one of the ambient temperature and the ambient pressure is lower than the preset low value or lower than the monitoring value at the previous moment, the injection pressure of the main fuel is increased based on the correction model.

10. The ignition system of the methanol lean engine according to claim 1, characterized in that: The main injector is arranged in the intake passage or offset on the cylinder head and located 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 outlet side holes facing away from the intake port; The multiple air inlet side holes and the multiple air outlet side holes are asymmetrically arranged about the central axis of the pre-combustion chamber, and the angle between the multiple air outlet side holes and the central axis is greater than the angle between the multiple air inlet side holes and the central axis, and the angle deviation range is 3°-20°.

11. The ignition system of the lean methanol engine according to claim 1, characterized in that: 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 a heating device is provided on the multi-electrode spark plug, and the control system adjusts the heating time of the heating device according to the monitored water temperature and ambient temperature to adjust the heating temperature of the multi-electrode spark plug and the pre-combustion chamber.

12. A vehicle, characterized in that: The invention comprises a vehicle body and a methanol lean engine arranged on the vehicle body, wherein the methanol lean engine is equipped with an ignition system according to any one of claims 1 to 11.

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