WO2024109963A2 - 一种可控温电热塞辅助压燃式甲醇发动机及其控制方法 - Google Patents

一种可控温电热塞辅助压燃式甲醇发动机及其控制方法 Download PDF

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WO2024109963A2
WO2024109963A2 PCT/CN2024/073455 CN2024073455W WO2024109963A2 WO 2024109963 A2 WO2024109963 A2 WO 2024109963A2 CN 2024073455 W CN2024073455 W CN 2024073455W WO 2024109963 A2 WO2024109963 A2 WO 2024109963A2
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temperature
engine
glow plug
methanol
control unit
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PCT/CN2024/073455
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English (en)
French (fr)
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朱建军
李志鑫
刘向阳
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太原理工大学
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Priority to GBGB2406551.8A priority Critical patent/GB202406551D0/en
Publication of WO2024109963A2 publication Critical patent/WO2024109963A2/zh

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/04—Introducing corrections for particular operating conditions
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/04—Introducing corrections for particular operating conditions
    • F02D41/06—Introducing corrections for particular operating conditions for engine starting or warming up
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/04—Introducing corrections for particular operating conditions
    • F02D41/08—Introducing corrections for particular operating conditions for idling
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/04—Introducing corrections for particular operating conditions
    • F02D41/10—Introducing corrections for particular operating conditions for acceleration
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/04—Introducing corrections for particular operating conditions
    • F02D41/12—Introducing corrections for particular operating conditions for deceleration
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/30—Controlling fuel injection
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D43/00—Conjoint electrical control of two or more functions, e.g. ignition, fuel-air mixture, recirculation, supercharging or exhaust-gas treatment
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D9/00—Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits
    • F02D9/08—Throttle valves specially adapted therefor; Arrangements of such valves in conduits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02N—STARTING OF COMBUSTION ENGINES; STARTING AIDS FOR SUCH ENGINES, NOT OTHERWISE PROVIDED FOR
    • F02N19/00—Starting aids for combustion engines, not otherwise provided for
    • F02N19/02—Aiding engine start by thermal means, e.g. using lighted wicks
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/30—Use of alternative fuels, e.g. biofuels

Definitions

  • the invention belongs to the technical field of vehicle engine control, and in particular relates to a temperature-controllable glow plug-assisted compression ignition methanol engine and a control method thereof.
  • Methanol as a new clean fuel, can replace gasoline and diesel and is an important part of new energy.
  • the engine uses methanol as an alternative fuel, the original engine will only need minor changes. It can improve its economic performance and reduce carbon emissions while meeting the power performance of the original engine.
  • Compression ignition engines have the advantages of low fuel consumption, high reliability, good altitude characteristics, low speed and high torque. However, methanol's low calorific value, high latent heat of vaporization and high auto-ignition temperature make it difficult to compression ignite methanol. Compression ignition methanol engines need to solve the problem of unstable combustion.
  • measures taken to ensure stable compression ignition of methanol engines include intake heating, diesel ignition, glow plug combustion assistance, etc.
  • the glow plug combustion assistance method can improve the cold start performance and solve the problem of difficult ignition of methanol engines.
  • the glow plug has the problems of short life, high energy consumption, and inability to change temperature with working conditions. Further measures need to be taken to optimize the combustion mode of glow plug assisted compression ignition.
  • the present invention provides a temperature-controllable glow plug-assisted compression ignition methanol engine and a control method thereof.
  • a temperature-controllable glow plug-assisted compression ignition methanol engine comprising an engine housing composed of a methanol engine water jacket, a methanol engine cylinder block, a methanol engine crankcase and an oil pan, a methanol engine cylinder head is arranged on the upper part of the engine housing, a methanol engine crankshaft and a methanol engine connecting rod are arranged in the engine housing, the methanol engine connecting rod drives the methanol engine crankshaft, the upper end of the methanol engine connecting rod is connected to the methanol engine piston, a cylinder is formed between the methanol engine cylinder head and the methanol engine piston, and a methanol engine exhaust manifold, a methanol fuel injector,
  • the methanol engine has a controllable temperature glow plug and an intake manifold, a methanol injector and a controllable temperature glow plug that extend into the cylinder, a throttle at the air inlet of the intake manif
  • the methanol injector, the controllable temperature glow plug and the throttle are controlled by an electronic control unit ECU of the methanol engine.
  • the electronic control unit ECU adjusts the temperature and changes the throttle opening according to the current load state of the methanol engine.
  • the load state calculates the average effective pressure of the engine according to the engine speed and effective power at this time as a judgment index.
  • the temperature-controllable glow plug is provided with a glow plug temperature sensor for measuring the surface temperature of the temperature-controllable glow plug and feeding back the temperature information to the electronic control unit ECU.
  • a throttle position sensor is arranged inside the throttle valve, and is used for monitoring the throttle opening and feeding back position information to an electronic control unit ECU.
  • the speed increases and the throttle opening increases, which increases the air velocity and flow rate of the engine.
  • the air velocity increases faster, forming an organized air swirl and intake tumble around the cylinder axis, increasing the turbulence intensity at the end of compression, accelerating the formation of methanol mixture, causing wrinkles in the flame front, increasing the area of the flame front and accelerating the heat transfer between the burned gas and the unburned gas, increasing the combustion rate, suppressing knock, reducing cycle changes, improving the lean burn capability, and improving the performance of the methanol engine.
  • the electronic control unit ECU controls the throttle opening and the glow plug temperature according to the set range of the stable working condition
  • the formula for mean effective pressure is: Where pme is the mean effective pressure, ⁇ is the number of strokes, Pe is the effective power, Vs is the single-cylinder working volume, i is the number of cylinders, and n is the speed.
  • the present invention has the following beneficial effects:
  • the temperature-controllable glow plug can select the appropriate glow plug temperature according to the actual working conditions. A high glow plug temperature is selected for a small load, and a lower glow plug temperature is selected for a large load to minimize the energy consumption of the glow plug and extend the life of the glow plug on the basis of full combustion of the methanol mixture.
  • FIG1 is a schematic diagram of a temperature-controllable glow plug-assisted compression ignition methanol engine according to the present invention
  • FIG2 is a schematic diagram of the arrangement of the glow plug and the injector of the temperature-controllable glow plug-assisted compression ignition methanol engine of the present invention
  • FIG3 is a curve showing the change of cylinder pressure with throttle opening under low load conditions
  • FIG4 is a curve showing the heat release rate changing with the throttle opening under low load conditions
  • FIG5 is a curve showing the change of cycle fluctuation rate with throttle opening under low load conditions
  • a temperature-controlled glow plug-assisted compression ignition methanol engine comprises a methanol
  • the engine housing is composed of an engine water jacket 11, a methanol engine cylinder block 12, a methanol engine crankcase 13 and an oil pan 14.
  • a methanol engine cylinder head 5 is arranged on the upper part of the engine housing.
  • a methanol engine crankshaft 1 and a methanol engine connecting rod 2 are arranged in the engine housing.
  • the methanol engine connecting rod 2 drives the methanol engine crankshaft 1.
  • the upper end of the methanol engine connecting rod 2 is connected to the methanol engine piston 3.
  • a cylinder is formed between the methanol engine cylinder head 5 and the methanol engine piston 3.
  • the throttle 9 at the air inlet of the methanol engine intake manifold 8 and the air flow meter 16 are arranged on the pipeline connecting the throttle 9 and the outside air.
  • the methanol injector 6, the temperature-controlled glow plug 7 and the throttle 9 are controlled by the methanol engine electronic control unit ECU.
  • the electronic control unit ECU performs temperature adjustment and changes the throttle opening according to the current load state of the methanol engine.
  • the load state calculates the average effective pressure of the engine according to the engine speed and effective power at this time as a judgment index.
  • the temperature-controlled glow plug 7 is provided with a glow plug temperature sensor for measuring the temperature of the temperature-controlled glow plug surface and feeding back temperature information to the electronic control unit ECU.
  • the throttle valve 9 is provided with a throttle position sensor for monitoring the throttle opening and feeding back position information to the electronic control unit ECU.
  • the injection amount of the methanol injector is obtained by the ECU controlling the power-on time of the injector.
  • the ECU can calculate the actual injection amount according to the power-on time.
  • the sum of the injection amount of each injector is the total fuel consumption.
  • the control strategy of the glow plug assisted compression ignition methanol engine optimizes the combustion of the methanol mixture by controlling the throttle opening to change the intake volume and controlling the glow plug temperature.
  • the mixture is too rich, the methanol will not burn completely, and the emission of harmful substances such as soot, Co and NOx will increase.
  • the mixture is too lean, the combustion speed of the fuel decreases, and the heat released by the combustion of this part of the mixture is converted into mechanical work relatively less, and the output torque decreases.
  • the selection of the appropriate mixture concentration can greatly improve the engine performance.
  • the selection of the glow plug temperature can enable the glow plug to achieve the optimal ignition performance of the methanol mixture while reducing energy consumption.
  • mean effective pressure is: Where pme is the mean effective pressure, ⁇ is the number of strokes, Pe is the effective power, Vs is the single cylinder displacement, i is the number of cylinders, and n is the speed.
  • the mean effective pressure of the engine can be calculated based on the engine speed and effective power at this time. The mean effective pressure can be used as an important indicator to judge the engine load state.
  • a control method for a temperature-controllable glow plug-assisted compression ignition methanol engine :
  • the electronic control unit ECU controls the excess air coefficient within the range of 1.4 to 1.8 by adjusting the throttle opening according to the real-time changing fuel consumption and the actual air flow.
  • the ECU first calculates the real-time changing excess air coefficient ⁇ according to the fuel consumption and the actual air flow fed back to the electronic control unit ECU by the air flow meter.
  • ⁇ 1.4 the ECU drives the motor to increase the throttle opening;
  • ⁇ 1.8 the throttle opening is reduced, so as to continuously correct the throttle opening, so that the fuel consumption increases while increasing the appropriate throttle opening, and the temperature of the glow plug is kept within the range of 1250°C ⁇ 1300°C.
  • the speed increases and the throttle opening increases, which increases the air velocity and flow rate of the engine.
  • the air velocity increases faster, forming an organized air swirl and intake tumble around the cylinder axis, increasing the turbulence intensity at the end of compression, accelerating the formation of methanol mixture, causing wrinkles in the flame front, increasing the area of the flame front and accelerating the heat transfer between the burned gas and the unburned gas, increasing the combustion rate, suppressing knock, reducing cycle changes, improving the lean burn capability, and improving the performance of the methanol engine.
  • the electronic control unit ECU reduces the oil supply and adjusts the throttle opening to control the excess air coefficient within the range of 1.2 to 1.4.
  • the ECU first calculates the real-time excess air coefficient ⁇ based on the fuel consumption and the actual air flow fed back by the air flow meter to the electronic control unit ECU.
  • ⁇ 1.2 the ECU drives the motor to increase the throttle opening;
  • ⁇ 1.4 the throttle opening is reduced, thereby continuously correcting the throttle opening, so that the fuel consumption is reduced while the throttle opening is appropriately reduced, and the temperature of the glow plug is maintained within the range of 950°C ⁇ 1050°C.
  • the various parameters that appear in the above control process are not conventional choices, but the optimal choices obtained after experiments.
  • the throttle opening or the glow plug temperature is changed under the same working condition, and the output torque, effective output power, fuel consumption, cylinder pressure, cycle fluctuation rate and emission data are obtained using a dynamometer, fuel consumption meter, combustion analyzer and emission meter.
  • the optimal throttle opening and the range of excess air coefficient and the optimal glow plug temperature range under the corresponding working condition are selected. The following takes the small load condition as an example.
  • the heat release rate curve at 6% to 18% throttle opening under the engine 1200r/min low load condition As shown in Figure 4, the heat release rate curve at 6% to 18% throttle opening under the engine 1200r/min low load condition. It can be seen from the figure that as the throttle opening increases, the heat release rate curve shows an overall upward trend, and the crankshaft angle heat release rate peak at 6°CA reaches a maximum of 46.88 at 12% opening, and decreases at 16% and 18%. It can be seen that the heat release rate is high in the opening range of 12% to 16%, and it decreases too much when it is greater than 16%.
  • the throttle opening should be controlled in the opening range of 12% to 16%. When the opening is 12%, the fuel consumption is measured to be 2.58kg/h, and the air flow is 19.28m3 /h. At this time, the corresponding excess air coefficient is 1.4831 ⁇ 1.8305.
  • the engine operates best when the throttle opening is within 12% to 16% under the current low-load condition.
  • the air flow and fuel consumption under this throttle opening range are measured experimentally, and the optimal excess air coefficient range at this time can be calculated to be about 1.5 to 1.8.
  • the optimal excess air coefficient range of the engine under low-load conditions at different speeds is also 1.5 to 1.8.
  • each parameter is similar to the above steps.
  • the optimal range of excess air coefficient and glow plug temperature is measured on the test bench and flashed into the ECU.
  • the ECU controls the throttle opening and the glow plug temperature and stabilizes the excess air coefficient and the glow plug temperature in the optimal range according to different working conditions.
  • the excess air coefficient range is that the ECU obtains the intake air volume L (m 3 /h) at this time according to the throttle position sensor information and the air flow sensor information, and then calculates the theoretical air-fuel ratio l and the actual air-fuel ratio l 0 at this time according to the total fuel consumption Q (kg/h).
  • the excess air coefficient is the actual The ratio of air-fuel ratio to theoretical air-fuel ratio.
  • the theoretical air-fuel ratio of methanol is 6.5
  • the excess air coefficient ⁇ l/l 0 .
  • the purpose of controlling the excess air coefficient is achieved by controlling the intake volume and total fuel consumption.
  • the temperature-controllable glow plug material is ceramic
  • the input voltage range is 20V to 28V
  • the controllable temperature range is 750°C to 1300°C.
  • the temperature can be fed back to the ECU in time, and the controller keeps the temperature within the range, so that the methanol mixture ignites and burns stably in the cylinder, and the stable ignition and combustion of the methanol mixture improves the engine economy and power.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)

Abstract

本发明公开一种可控温电热塞辅助压燃式甲醇发动机及其控制方法，涉及车用发动机控制技术领域，通过使用可控温电热塞来满足不同发动机工况下甲醇燃烧对温度的需求，喷油器直接把甲醇喷到发动机燃烧室内部，通过燃烧室内部可控温电热塞促使甲醇混合气稳定可靠着火，控制电热塞温度和缸内甲醇混合气的过量空气系数可以使发动机不同工况下着火燃烧达到最优效果。本发明中电热塞温度控制范围为750℃～1300℃，过量空气系数调节范围1.2≤λ≤1.8。电热塞温度与过量空气系数协同控制促进甲醇发动机稳定燃烧，使压燃式甲醇发动机达到最优的经济性与动力性。

Description

一种可控温电热塞辅助压燃式甲醇发动机及其控制方法 技术领域
本发明属于车用发动机控制技术领域，特别是涉及一种可控温电热塞辅助压燃式甲醇发动机及其控制方法。
背景技术
全球变暖，是目前为止对地球和人类最为严重的威胁因素之一，各行各业都在逐步减少使用和倚靠化石燃料。甲醇作为一种新型清洁燃料可以替代汽油、柴油，是新能源的重要组成部分。发动机燃用甲醇作为替代燃料时对原发动机的改动较小，能在满足原发动机的动力性能基础上，改善其经济性能与减少碳排放。
压燃式发动机具有油耗低、可靠性高、高度特性好、转速低、转矩大等优点，而甲醇的低热值，高汽化潜热及高自燃温度的特点使得甲醇难以被压燃，压燃式甲醇发动机需要解决燃烧不稳定的问题。
目前为使甲醇发动机稳定压燃采取措施包括进气加热、柴油引燃、电热塞助燃等。其中电热塞助燃方式可以改善冷启动性能，解决甲醇发动机点火难的问题，而电热塞存在寿命短、能耗高、无法随工况变化温度的问题，需要采取进一步措施优化电热塞辅助压燃的这种燃烧模式。
发明内容
本发明为了解决上述问题，提供一种可控温电热塞辅助压燃式甲醇发动机及其控制方法。
本发明采取以下技术方案：一种可控温电热塞辅助压燃式甲醇发动机，包括由甲醇发动机水套、甲醇发动机缸体、甲醇发动机曲轴箱以及油底壳组成的发动机壳体，发动机壳体上部设置甲醇发动机缸盖，所述发动机壳体内设置甲醇发动机曲轴以及甲醇发动机连杆，甲醇发动机连杆驱动甲醇发动机曲轴，甲醇发动机连杆上端连接甲醇发动机活塞，甲醇发动机缸盖与甲醇发动机活塞之间形成气缸，所述甲醇发动机缸盖上设置甲醇发动机排气歧管、甲醇喷油器、 可控温电热塞以及甲醇发动机进气歧管，甲醇喷油器与可控温电热塞都伸入气缸内，甲醇发动机进气歧管的进气口处的节气门，节气门与外界空气连通的管路上设置空气流量计，所述甲醇喷油器、可控温电热塞与节气门由甲醇发动机电子控制单元ECU控制，电子控制单元ECU根据甲醇发动机当前的负荷状态进行温度调节与节气门开度变化；所述负荷状态根据此时发动机转速与有效功率计算出发动机的平均有效压力作为判断指标。
所述可控温电热塞上设置有电热塞温度传感器，用于测量可控温电热塞表面温度并向电子控制单元ECU反馈温度信息。
所述节气门内设置有节气门位置传感器，用于监测节气门开度并向电子控制单元元ECU反馈位置信息。
一种可控温电热塞辅助压燃式甲醇发动机的控制方法，
S1：当发动机启动以及进入怠速状态时，电子控制单元ECU控制节气门开度保持在4°～8°范围内，此时进气量小，过量空气系数被控制保持在0.8～1.0范围内，可控温电热塞的温度保持在1200℃～1300℃范围内。
S2：当发动机平稳加速时，电子控制单元ECU根据实时变化的油耗量，调整节气门9开度，空气流量计16向电子控制单元ECU反馈空气流量的变化并进一步修正节气门9开度，使得油耗量增大的同时节气门开度随之增大，以此控制过量空气系数在1.4～1.8范围内，电热塞温度保持在1250℃～1300℃范围内。
发动机加速时由于转速加大，以及节气门开度加大，使得发动机吸入的空气流速以及流量加大。由于每循环的相同进气门开启时间内进气量加大，空气流速加大更快形成绕垂直于气缸轴线的有组织的空气旋流及进气滚流，增加压缩终了时的湍流强度，加速甲醇混合气的形成，从而使火焰前锋发生皱褶，增加火焰前锋的面积并加速已燃气体与未燃气体之间热量传递，提高燃烧速率，抑制爆震，减少循环变动，提高稀燃能力，改善甲醇发动机的性能。
S3：当发动机急加速时，电子控制单元ECU控制节气门全开，保证瞬时的进气量满足甲醇稳定燃烧，电热塞温度保持在1275℃～1300℃范围内。
S4：发动机平稳减速时，电子控制单元ECU减少油量供应，并调整节气 门9开度，空气流量计16向电子控制单元ECU反馈实时空气流量的变化并进一步修正节气门9开度，使得油耗量减少的同时节气门开度随之减小，以此控制过量空气系数在1.2～1.4范围内，电热塞温度保持在950℃～1050℃范围内。
S5：发动机紧急制动时，ECU切断油量供应，此时节气门开度调至2°～5°，电热塞保持在700℃～750℃。
过量空气系数的计算过程如下，电子控制单元ECU根据节气门位置传感器以及空气流量传感器采集的信息得到此时的进气量L(m3/h)，由总燃油消耗量Q(kg/h)计算出此时的实际空燃比l＝1.29×L/Q，甲醇理论空燃比l0为6.5，则理论进气量为L0＝l0×Q/1.29，过量空气系数为实际空燃比l与理论空燃比l0的比值，λ＝l/l0，同时λ也为实际进气量与理论进气量的比值，λ＝L/L0。
所述S3中，当发动机加速过程结束后进入如下的稳定工况，电子控制单元ECU根据稳定工况的设定范围控制节气门开度与电热塞温度；
S31：当平均有效压力为0.2MPa～0.4MPa时，发动机为小负荷工况，此时电子控制单元ECU控制节气门开度，使过量空气系数λ保持在范围1.5≤λ≤1.8内；电子控制单元ECU根据电热塞温度传感器信号得到此时的可控温电热塞温度，并控制可控温电热塞的温度使其达到1150℃～1200℃范围内。
S32：当平均有效压力为0.4MPa～0.7MPa时，发动机为中负荷工况，此时电子控制单元ECU控制节气门开度，使过量空气系数λ范围为1.4≤λ≤1.7。电子控制单元ECU根据电热塞温度传感器信号得到此时的可控温电热塞温度，并控制可控温电热塞的温度使其达到1050℃～1150℃。
S33：当平均有效压力大于等于0.7MPa时，发动机为大负荷工况，此时电子控制单元ECU控制节气门开度，使过量空气系数λ范围为1.2≤λ≤1.4；电子控制单元ECU根据电热塞温度传感器信号得到此时的可控温电热塞温度，并控制可控温电热塞温度使其达到1000℃～1050℃。
平均有效压力的公式为式中pme为平均有效压力，τ为冲程数，Pe为有效功率，VS为单缸工作容积，i为气缸数，n为转速。
与现有技术相比，本发明具有以下有益效果：
1.可控温电热塞能够根据实际工况需要来选择合适的电热塞温度，小负荷选择高电热塞温度，大负荷则降低电热塞温度以满足在甲醇混合气充分燃烧的基础上最大限度的减少电热塞的能耗，延长电热塞寿命。
2.合理的过量空气系数与相应的电热塞温度配合，小负荷时高电热塞温度高过量空气系数使得燃烧更充分提高热效率，中大负荷适当增加的混合气浓度可以优化甲醇混合气着火性能更容易压燃，并降低循环波动率，降低燃油消耗量，降低未燃甲醇、甲醛、甲酸等有害物质排放。
附图说明
图1是本发明可控温电热塞辅助压燃式甲醇发动机示意图；
图2是本发明可控温电热塞辅助压燃式甲醇发动机电热塞与喷油器布置示意图；
图3是小负荷工况下缸内压力随节气门开度变化的曲线；
图4是小负荷工况下放热率随节气门开度变化的曲线；
图5是小负荷工况下循环波动率随节气门开度变化的曲线；
图中：1-甲醇发动机曲轴，2-甲醇发动机连杆，3-甲醇发动机活塞，4-甲醇发动机排气歧管，5-甲醇发动机缸盖，6-甲醇喷油器，7-可控温电热塞，8-甲醇发动机进气歧管，9-电控节气门，10-电子控制单元，11-甲醇发动机水套，12-甲醇发动机缸体，13-甲醇发动机曲轴箱，14-油底壳，15-输出法兰盘，16-空气流量计。
具体实施方式
为使本发明实施例的目的、技术方案和优点更加清楚，下面将对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本发明的一部分实施例，而不是全部的实施例；基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
如图1、2所示，一种可控温电热塞辅助压燃式甲醇发动机，包括由甲醇 发动机水套11、甲醇发动机缸体12、甲醇发动机曲轴箱13以及油底壳14组成的发动机壳体，发动机壳体上部设置甲醇发动机缸盖5，所述发动机壳体内设置甲醇发动机曲轴1以及甲醇发动机连杆2，甲醇发动机连杆2驱动甲醇发动机曲轴1，甲醇发动机连杆2上端连接甲醇发动机活塞3，甲醇发动机缸盖5与甲醇发动机活塞3之间形成气缸，所述甲醇发动机缸盖5上设置甲醇发动机排气歧管4、甲醇喷油器6、可控温电热塞7以及甲醇发动机进气歧管8，甲醇喷油器6与可控温电热塞7都伸入气缸内，甲醇发动机进气歧管8的进气口处的节气门9，节气门9与外界空气连通的管路上设置空气流量计16，所述甲醇喷油器6、可控温电热塞7与节气门9由甲醇发动机电子控制单元ECU控制，电子控制单元ECU根据甲醇发动机当前的负荷状态进行温度调节与节气门开度变化；所述负荷状态根据此时发动机转速与有效功率计算出发动机的平均有效压力作为判断指标。
可控温电热塞7上设置有电热塞温度传感器，用于测量可控温电热塞表面温度并向电子控制单元ECU反馈温度信息。节气门9内设置有节气门位置传感器，用于监测节气门开度并向电子控制单元元ECU反馈位置信息。所述的甲醇喷油器的喷油量由ECU控制喷油器加电时间所得，ECU可以根据加电时间计算出实际喷油量，每支喷油器喷油量总和为总燃油消耗量。
电热塞辅助压燃式甲醇发动机的控制策略通过控制节气门开度改变进气量并控制电热塞温度来使甲醇混合气燃烧达到最优。当混合气过浓时，会使甲醇燃烧不完全，碳烟、Co与NOx等有害物排放增多。当混合气过稀时，燃料的燃烧速度降低，这部分混合气燃烧放出的热量中变为机械功的相对较少，输出扭矩下降。合适的混合气浓度选择对发动机性能有很大改善，电热塞温度的选择可以使电热塞在使甲醇混合气的着火性能达到最优的同时降低能耗。
平均有效压力的公式为式中pme为平均有效压力，τ为冲程数，Pe为有效功率，VS为单缸工作容积，i为气缸数，n为转速。根据此时发动机转速与有效功率可以计算出发动机的平均有效压力，平均有效压力可以作为判断发动机负荷状态的重要指标。
一种可控温电热塞辅助压燃式甲醇发动机的控制方法：
S1：当发动机启动以及进入怠速状态时，电子控制单元ECU控制节气门9开度保持在4°～8°范围内，此时进气量小，过量空气系数被控制保持在0.8～1.0范围内，可控温电热塞7的温度保持在1200℃～1300℃范围内。可控温电热塞7温度保持在1200℃～1300℃范围内，以保证喷入的甲醇可以迅速被压燃，发动机快速启动。
S2：当发动机平稳加速时，电子控制单元ECU根据实时变化的油耗量与实际空气流量，通过调整节气门开度控制过量空气系数在1.4～1.8范围内。ECU首先根据油耗量与空气流量计向电子控制单元ECU反馈的实际空气流量计算出实时变化的过量空气系数λ。当λ≤1.4时，则ECU驱动电机增大节气门开度；当λ≥1.8则减小节气门开度，以此不断修正节气门开度，使得油耗量增大的同时增大合适的节气门开度，并且电热塞温度保持在1250℃～1300℃范围内。
发动机加速时由于转速加大，以及节气门开度加大，使得发动机吸入的空气流速以及流量加大。由于每循环的相同进气门开启时间内进气量加大，空气流速加大更快形成绕垂直于气缸轴线的有组织的空气旋流及进气滚流，增加压缩终了时的湍流强度，加速甲醇混合气的形成，从而使火焰前锋发生皱褶，增加火焰前锋的面积并加速已燃气体与未燃气体之间热量传递，提高燃烧速率，抑制爆震，减少循环变动，提高稀燃能力，改善甲醇发动机的性能。
S3：当发动机急加速时，电子控制单元ECU控制节气门9全开，保证瞬时的进气量满足甲醇稳定燃烧，电热塞温度保持在1275℃～1300℃范围内。当发动机加速过程结束后进入如下的稳定工况，电子控制单元ECU根据稳定工况的设定范围控制节气门开度与电热塞温度。
S31：当平均有效压力为0.2MPa～0.4MPa时，发动机为小负荷工况，此时电子控制单元ECU控制节气门9开度，使过量空气系数λ保持在范围1.5≤λ≤1.8内；电子控制单元ECU根据电热塞温度传感器信号得到此时的可控温电热塞7温度，并控制可控温电热塞7的温度使其达到1150℃～1200℃范围内。以使小负荷工况下甲醇混合气燃烧达到最优效果，此时发动机输出功率增大，平均有效压力在当前范围内增加。
S32：当平均有效压力为0.4MPa～0.7MPa时，发动机为中负荷工况，此时电子控制单元ECU控制节气门9开度，使过量空气系数λ范围为1.4≤λ≤1.7；电子控制单元ECU根据电热塞温度传感器信号得到此时的可控温电热塞7温度，并控制可控温电热塞7的温度使其达到1050℃～1150℃。以使中负荷工况下甲醇混合气燃烧达到最优效果，此时发动机输出功率增大，平均有效压力在当前范围内增加。
S33：当平均有效压力大于等于0.7MPa时，发动机为大负荷工况，此时电子控制单元ECU控制节气门9开度，使过量空气系数λ范围为1.2≤λ≤1.4；电子控制单元ECU根据电热塞温度传感器信号得到此时的可控温电热塞7温度，并控制可控温电热塞7温度使其达到1000℃～1050℃。以使大负荷工况下甲醇混合气燃烧达到最优效果，此时发动机输出功率增大，平均有效压力在当前范围内增加。
S4：发动机平稳减速时，电子控制单元ECU减少油量供应，并调整节气门开度，以此控制过量空气系数在1.2～1.4范围内。ECU首先根据油耗量与空气流量计向电子控制单元ECU反馈的实际空气流量计算出实时变化的过量空气系数λ。当λ≤1.2时，则ECU驱动电机增大节气门开度；当λ≥1.4则减小节气门开度，以此不断修正节气门开度，使得油耗量减少的同时减小适当的节气门开度，并且电热塞温度保持在950℃～1050℃范围内。
S5：发动机紧急制动时，ECU切断油量供应，此时节气门9开度调至2°～5°，电热塞保持在700℃～750℃。
上述控制过程出现的各种参数并非常规选择，而是经过实验后得出的最优选择。实验过程中，同一工况下只改变节气门开度或电热塞温度，并使用测功机、燃油消耗仪、燃烧分析仪、排放仪得到输出转矩、有效输出功率、燃油消耗量、缸内压力、循环波动率以及排放量等数据。根据实验数据选择最优的节气门开度及对应工况下的过量空气系数范围与最优电热塞温度范围。以下以小负荷工况为例。
如图3为发动机1200r/min小负荷工况下6％～18％节气门开度时的缸内压力曲线，从图中可知随着节气门开度的增大，缸内压力曲线整体呈上升趋势， 最高压力逐渐增大，但当节气门开度为18％时曲轴转角在10.4℃A缸内最高压力为60.42bar，16％开度时曲轴转角在9.5℃A最高缸压为62.02bar，最高缸压下降了3％。则可知节气门开度继续增大会使缸压继续下降，所以最优的节气门开度控制在16％以内。开度为16％时油耗量测得2.73kg/h，空气流量测得25.18m3/h，则对应的计算所得过量空气系数λ＝1.8305。
如图4为发动机1200r/min小负荷工况下6％～18％节气门开度时的放热率曲线，从图中可知随着节气门开度的增大，放热率曲线整体呈上升趋势，且12％开度时曲轴转角在6℃A放热率峰值达到最高46.88，16％与18％则时有所下降。则可知12％～16％开度范围内放热率较高，大于16％下降过多，节气门开度应控制在12％～16％开度范围。开度为12％时测得油耗量为2.58kg/h，空气流量为19.28m3/h此时对应的过量空气系数1.4831≤λ≤1.8305。
如图5为发动机1200r/min小负荷工况下6％～18％节气门开度时的循环波动率曲线，从图中可知随着节气门开度的增大，循环波动率逐渐升高，循环波动率大会导致燃烧不正常甚至失火的循环数逐渐增多，碳氢化合物等不可能完全燃烧产物增多，动力经济性下降。同时，由于燃烧过程不稳定，也使得振动噪声增大，零部件寿命下降。因此再次证明节气门开度不可继续增大，控制在范围内为最优解。
综上实验数据可以得出当前小负荷工况下节气门开度12％～16％内的发动机运行状态最好，在此节气门开度范围下的空气流量与油耗量由实验测得，即可计算出此时的最优过量空气系数范围约为1.5～1.8。再经实验证明发动机在不同转速的小负荷工况下最优过量空气系数范围也为1.5～1.8。
具体的，上述的各个参数的选择均和以上的步骤相似，在实验台架上测得过量空气系数与电热塞温度的最优范围，并刷写进ECU。在实车上由ECU控制节气门开度与电热塞温度并使其根据不同工况条件使过量空气系数与电热塞温度稳定在最优范围。
具体的，控制过量空气系数范围是ECU根据所述的节气门位置传感器信息、空气流量传感器信息得到此时的进气量L(m3/h)，再由所述的总燃油消耗量Q(kg/h)计算出此时的理论空燃比l与实际空燃比l0，过量空气系数为实际 空燃比与理论空燃比的比值，甲醇的理论空燃比为6.5，实际空燃比l＝1.29×L/Q，过量空气系数λ＝l/l0。控制进气量与总燃油消耗量达到控制过量空气系数的目的。
具体的，可控温电热塞材料为陶瓷，输入电压范围为20V～28V，可控制温度范围为750℃～1300℃。可以及时向ECU反馈温度，控制器使温度始终保持在范围内，甲醇混合气在缸内着火燃烧稳定，甲醇混合气着火燃烧稳定改善发动机经济性和动力性。
本说明书所附图式所绘示的结构、比例、大小等，均仅用以配合说明书所揭示的内容，以供熟悉此技术的人士了解与阅读，并非用以限定本发明可实施的限定条件，故不具技术上的实质意义，任何结构的修饰、比例关系的改变或大小的调整，在不影响本发明所能产生的功效及所能达成的目的下，均应仍落在本发明所揭示的技术内容得能涵盖的范围内。同时，本说明书中所引用的如“上”、“下”、“左”、“右”、“中间”及“一”等的用语，亦仅为便于叙述的明了，而非用以限定本发明可实施的范围，其相对关系的改变或调整，在无实质变更技术内容下，当亦视为本发明可实施的范畴。
最后应说明的是：以上各实施例仅用以说明本发明的技术方案，而非对其限制；尽管参照前述各实施例对本发明进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本发明各实施例技术方案的范围。

Claims (7)

  1. 一种可控温电热塞辅助压燃式甲醇发动机，其特征在于：包括由甲醇发动机水套(11)、甲醇发动机缸体(12)、甲醇发动机曲轴箱(13)以及油底壳(14)组成的发动机壳体，发动机壳体上部设置甲醇发动机缸盖(5)，所述发动机壳体内设置甲醇发动机曲轴(1)以及甲醇发动机连杆(2)，甲醇发动机连杆(2)驱动甲醇发动机曲轴(1)，甲醇发动机连杆(2)上端连接甲醇发动机活塞(3)，甲醇发动机缸盖(5)与甲醇发动机活塞(3)之间形成气缸，所述甲醇发动机缸盖(5)上设置甲醇发动机排气歧管(4)、甲醇喷油器(6)、可控温电热塞(7)以及甲醇发动机进气歧管(8)，甲醇喷油器(6)与可控温电热塞(7)都伸入气缸内，甲醇发动机进气歧管(8)的进气口处的节气门(9)，节气门(9)与外界空气连通的管路上设置空气流量计(16)，所述甲醇喷油器(6)、可控温电热塞(7)与节气门(9)由甲醇发动机电子控制单元ECU控制，电子控制单元ECU根据甲醇发动机当前的负荷状态进行温度调节与节气门开度变化；所述负荷状态根据此时发动机转速与有效功率计算出发动机的平均有效压力作为判断指标。
  2. 根据权利要求1所述的可控温电热塞辅助压燃式甲醇发动机，其特征在于：所述可控温电热塞(7)上设置有电热塞温度传感器，用于测量可控温电热塞表面温度并向电子控制单元ECU反馈温度信息。
  3. 根据权利要求2所述的可控温电热塞辅助压燃式甲醇发动机，其特征在于：所述节气门(9)内设置有节气门位置传感器，用于监测节气门开度并向电子控制单元元ECU反馈位置信息。
  4. 一种如权利要求3所述的可控温电热塞辅助压燃式甲醇发动机的控制方法，其特征在于：
    S1：当发动机启动以及进入怠速状态时，电子控制单元ECU控制节气门(9)开度保持在4°～8°范围内，此时进气量小，过量空气系数被控制保持在0.8～1.0范围内，可控温电热塞(7)的温度保持在1200℃～1300℃范围内；
    S2：当发动机平稳加速时，电子控制单元ECU根据实时变化的油耗量，调整节气门(9)开度，空气流量计(16)向电子控制单元ECU反馈空气流量 的变化并进一步修正节气门(9)开度，使得油耗量增大的同时节气门开度随之增大，以此控制过量空气系数在1.4～1.8范围内，电热塞温度保持在1250℃～1300℃范围内；
    S3：当发动机急加速时，电子控制单元ECU控制节气门(9)全开，保证瞬时的进气量满足甲醇稳定燃烧，电热塞温度保持在1275℃～1300℃范围内；
    S4：发动机平稳减速时，电子控制单元ECU减少油量供应，并调整节气门(9)开度，空气流量计(16)向电子控制单元ECU反馈实时空气流量的变化并进一步修正节气门(9)开度，使得油耗量减少的同时节气门开度随之减小，以此控制过量空气系数在1.2～1.4范围内，电热塞温度保持在950℃～1050℃范围内；
    S5：发动机紧急制动时，ECU切断油量供应，此时节气门(9)开度调至2°～5°，电热塞保持在700℃～750℃。
  5. 根据权利要求4所述的可控温电热塞辅助压燃式甲醇发动机的控制方法，其特征在于：所述过量空气系数的计算过程如下，电子控制单元ECU根据节气门位置传感器以及空气流量传感器采集的信息得到此时的进气量L，再由总燃油消耗量Q计算出此时的理论空燃比l0与实际空燃比l＝1.29×L/Q，过量空气系数为实际空燃比与理论空燃比的比值，λ＝l/l0。
  6. 根据权利要求5所述的可控温电热塞辅助压燃式甲醇发动机的控制方法，其特征在于：所述S3中，当发动机加速过程结束后进入如下的稳定工况，电子控制单元ECU根据稳定工况的设定范围控制节气门开度与电热塞温度；
    S31：当平均有效压力为0.2MPa～0.4MPa时，发动机为小负荷工况，此时电子控制单元ECU控制节气门(9)开度，使过量空气系数λ保持在范围1.5≤λ≤1.8内；电子控制单元ECU根据电热塞温度传感器信号得到此时的可控温电热塞(7)温度，并控制可控温电热塞(7)的温度使其达到1150℃～1200℃范围内；
    S32：当平均有效压力为0.4MPa～0.7MPa时，发动机为中负荷工况，此时电子控制单元ECU控制节气门(9)开度，使过量空气系数λ范围为1.4≤λ≤1.7；电子控制单元ECU根据电热塞温度传感器信号得到此时的可控温电 热塞(7)温度，并控制可控温电热塞(7)的温度使其达到1050℃～1150℃；
    S33：当平均有效压力大于等于0.7MPa时，发动机为大负荷工况，此时电子控制单元ECU控制节气门(9)开度，使过量空气系数λ范围为1.2≤λ≤1.4；电子控制单元ECU根据电热塞温度传感器信号得到此时的可控温电热塞(7)温度，并控制可控温电热塞(7)温度使其达到1000℃～1050℃。
  7. 根据权利要求6所述的可控温电热塞辅助压燃式甲醇发动机的控制方法，其特征在于：平均有效压力的公式为式中pme为平均有效压力，τ为冲程数，Pe为有效功率，VS为单缸工作容积，i为气缸数，n为转速。
PCT/CN2024/073455 2022-11-22 2024-01-22 一种可控温电热塞辅助压燃式甲醇发动机及其控制方法 WO2024109963A2 (zh)

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