WO2022262276A1 - 一种燃烧系统的控制方法、燃烧系统及柴油机 - Google Patents

一种燃烧系统的控制方法、燃烧系统及柴油机 Download PDF

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WO2022262276A1
WO2022262276A1 PCT/CN2022/073116 CN2022073116W WO2022262276A1 WO 2022262276 A1 WO2022262276 A1 WO 2022262276A1 CN 2022073116 W CN2022073116 W CN 2022073116W WO 2022262276 A1 WO2022262276 A1 WO 2022262276A1
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Prior art keywords
cylinder pressure
time
cylinder
fuel injection
main fuel
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PCT/CN2022/073116
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English (en)
French (fr)
Inventor
谭旭光
周鹏
佟德辉
庞斌
谷允成
刘晓鑫
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潍柴动力股份有限公司
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Application filed by 潍柴动力股份有限公司 filed Critical 潍柴动力股份有限公司
Priority to JP2023566498A priority Critical patent/JP2024515824A/ja
Priority to EP22823771.5A priority patent/EP4357603A1/en
Priority to US18/290,406 priority patent/US20240360798A1/en
Priority to KR1020237041890A priority patent/KR20240004974A/ko
Publication of WO2022262276A1 publication Critical patent/WO2022262276A1/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
    • F02D35/00—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
    • F02D35/02—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions
    • F02D35/023—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions by determining the cylinder pressure
    • 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
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/40—Controlling fuel injection of the high pressure type with means for controlling injection timing or duration
    • F02D41/402—Multiple injections
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D35/00—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
    • F02D35/02—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions
    • F02D35/028—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions by determining the combustion timing or phasing
    • 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
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
    • F02D41/1406—Introducing closed-loop corrections characterised by the control or regulation method with use of a optimisation method, e.g. iteration
    • 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
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/3809—Common rail control systems
    • F02D41/3827—Common rail control systems for diesel engines
    • 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
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/3809—Common rail control systems
    • F02D41/3836—Controlling the fuel pressure
    • 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
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/40—Controlling fuel injection of the high pressure type with means for controlling injection timing or duration
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/06—Fuel or fuel supply system parameters
    • F02D2200/0602—Fuel pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/10—Parameters related to the engine output, e.g. engine torque or engine speed
    • F02D2200/101—Engine speed
    • 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
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/40—Controlling fuel injection of the high pressure type with means for controlling injection timing or duration
    • F02D41/402—Multiple injections
    • F02D41/403—Multiple injections with pilot injections
    • 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
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/40—Controlling fuel injection of the high pressure type with means for controlling injection timing or duration
    • F02D41/402—Multiple injections
    • F02D41/405—Multiple injections with post injections

Definitions

  • the invention relates to the technical field of diesel engines, in particular to a method for controlling a combustion system, a combustion system and a diesel engine.
  • the combustion organization of existing diesel engines is mainly based on diffusion combustion, and the combustion speed is largely limited by the mixing speed of oil and gas.
  • the current high-pressure common rail diesel engines all use one main fuel injection, and the entrainment effect of a single high-pressure injection mainly occurs in the atomization area, and the entrainment effect is weakened in the middle of the oil beam, and the oil-gas mixing effect is poor.
  • High, for a four-stroke diesel engine the time used to organize the mixing of oil and gas is very short. After the jets and droplets produced by a single injection undergo broken atomization, it is difficult to diffuse in the combustion chamber in time to form a uniform mixture with air, thereby limiting combustion. The process proceeds quickly, further limiting the power output of the diesel engine.
  • the object of the present invention is to provide a method for controlling a combustion system, a combustion system and a diesel engine, so as to improve the uniformity of fuel injection mixed with air.
  • the present invention provides a method for controlling a combustion system
  • the combustion system includes a piston, an injector and a cylinder
  • the piston can reciprocate up and down in the cylinder
  • the injector In each movement cycle of , at least the first main fuel injection and the second main fuel injection are sequentially executed, and the injector continues to inject fuel during the process from the first main fuel injection to the second main fuel injection;
  • the corresponding injection pressure when the fuel injection rate is the highest during the first main fuel injection process of the injector is the first injection pressure, and when the fuel injection rate is the highest during the second main fuel injection process of the fuel injector
  • the corresponding injection pressure is the second injection pressure;
  • the control method of the combustion system includes:
  • the cylinder pressure drops from the cylinder pressure upper threshold
  • the change rate of the slope of the cylinder pressure change curve at each time point is within the range of the set slope change rate, and the cylinder pressure drops from the cylinder pressure upper threshold to the set
  • the angle that the corresponding crankshaft rotates within the period of time for setting the cylinder pressure is not less than the first preset angle of rotation.
  • the cylinder pressure during the first main fuel injection has not reached the cylinder pressure upper limit threshold, iteratively adjust at least one of the start time, end time and current first injection pressure of the first main fuel injection,
  • the cylinder pressure during the process of the first main fuel injection reaches the cylinder pressure upper limit threshold at least part of the time, and when the cylinder pressure reaches the cylinder pressure upper limit threshold for the first time, the corresponding crank angle does not exceed the first angle,
  • the angle that the crankshaft turns during the time period when the cylinder pressure rises from the first cylinder pressure to the cylinder pressure upper limit threshold is not less than the second preset rotation angle; wherein, when the cylinder pressure is equal to the first cylinder pressure, it corresponds to The volume of the cylinder is the same as the volume of the cylinder corresponding to the first time the cylinder pressure reaches the upper threshold of the cylinder pressure.
  • the time when the injector starts the first main fuel injection is the first time t 1 , and the injector starts the first main fuel injection and the second The time at which the rate of fuel injected between the main fuel injections is the lowest is the second time t 2 , and the first injection pressure is P 1 ;
  • the cylinder pressure P in the cylinder is collected in real time, the rotation angle of the crankshaft is collected in real time, and the cylinder pressure P is compared with the cylinder pressure upper limit threshold Pmax , and it is judged whether the rotation angle of the crankshaft exceeds the first angle;
  • increasing the value of the first injection pressure P1; and/or, reducing the overall difference between the second time t2 and the first time t1 includes:
  • the value of the first injection pressure P1 is increased by the first set value, and the first time t1 and/or the second time t2 are adjusted The overall difference between the second time t2 and the first time t1 is reduced by the second set value.
  • the crank angle ⁇ a when the cylinder volume equals the real-time cylinder volume V corresponds to the crank angle ⁇ a when the cylinder goes up and the crank angle ⁇ b when the cylinder goes down;
  • ⁇ 1 ⁇ n increase the value of the first injection pressure P 1 by a third set value, and/or adjust the first time t 1 and/or the second time t 2 so that the second time t 2 and The difference of the first time t 1 is overall reduced by the fourth set value.
  • the second injection pressure is P 2 ; and at least one of the duration of the second main fuel injection and the second injection pressure is adjusted iteratively so that the During the second main fuel injection process, during the time period when the cylinder pressure drops from the cylinder pressure upper threshold to the set cylinder pressure, the change rate of the slope of the cylinder pressure change curve at each time point is at the set slope Within the range of rate of change, and making the cylinder pressure drop from the cylinder pressure upper limit threshold to the set cylinder pressure, the angle corresponding to the crankshaft rotation during the time period is not less than the first preset rotation angle includes:
  • the control method of the combustion system further includes:
  • the present invention provides a combustion system, which is used to implement the control method of the combustion system described in any of the above solutions, the combustion system includes a piston, an injector, a cylinder and a controller, and the controller is used to control the The injector performs at least the first main fuel injection and the second main fuel injection in sequence in each movement cycle of the piston, and the injector performs the first main fuel injection to the second main fuel injection Continuous fuel injection during the process;
  • the controller is used to determine the duration of the first main fuel injection and the first injection pressure, so that the cylinder pressure at least part of the time during the first main fuel injection can reach the cylinder pressure upper threshold;
  • the controller is used to iteratively adjust at least one of the duration of the second main fuel injection and the second injection pressure, so that during the second main fuel injection, the cylinder pressure changes from the During the time period when the cylinder pressure upper limit threshold drops to the set cylinder pressure, the change rate of the slope of the cylinder pressure change curve at each time point is within the set slope change rate range, and the cylinder pressure is changed from the cylinder pressure to During the time period when the upper threshold value drops to the set cylinder pressure, the corresponding crankshaft rotates an angle not less than the first preset angle of rotation.
  • the present invention provides a diesel engine, including the combustion system in the above solution.
  • the invention provides a control method of a combustion system, a combustion system and a diesel engine.
  • the control method of the combustion system can superimpose the high-speed oil beam of the two main fuel injections on the space intensity of the entrainment effect in the cylinder through two main fuel injections, Realize the two-time organization of the oil beam to the flow field in the cylinder, strengthen the turbulent flow in the cylinder, increase the mixing rate of oil and gas in the cylinder, and effectively improve the combustion speed in the middle and late stages of combustion and the utilization rate of air in the cylinder; and by determining the first main fuel injection
  • the duration and the first injection pressure ensure the cylinder pressure so that the cylinder pressure at least part of the time during the first main fuel injection can reach the cylinder pressure upper threshold; iteratively adjust the duration of the second main fuel injection and the At least one of the second injection pressures, so that during the second main fuel injection process, during the time period when the cylinder pressure drops from the cylinder pressure upper threshold to the set cylinder pressure, the cylinder pressure variation curve is The
  • Fig. 1 is a schematic diagram of the fuel injection law of the fuel injector in Embodiment 2 of the present invention
  • Fig. 2 is the relationship diagram between instantaneous heat release rate and crankshaft angle in the second embodiment of the present invention
  • Fig. 3 is a graph showing the entrainment combustion rate and cylinder pressure indicator in Example 2 of the present invention.
  • first position and second position are two different positions, and "above”, “above” and “above” the first feature on the second feature include that the first feature is on the second feature. Directly above and obliquely above, or simply means that the first feature level is higher than the second feature. "Below”, “beneath” and “under” the first feature to the second feature include that the first feature is directly below and obliquely below the second feature, or simply means that the first feature has a lower level than the second feature.
  • connection should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connected, or integrally connected; it may be mechanically connected or electrically connected; it may be directly connected or indirectly connected through an intermediary, and it may be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention in specific situations.
  • the combustion control system includes a piston, a fuel injector and a cylinder, wherein the piston can reciprocate up and down in the cylinder, and the fuel injector is used to inject fuel into the combustion chamber provided on the piston.
  • the combustion control system further includes a controller, the controller is used to control the injector to perform at least the first main fuel injection and the second main fuel injection in sequence in each movement cycle of the piston, and the injector performs between the first main fuel injection and the second main fuel injection. Continuous fuel injection during the second main fuel injection, and the rate of the fuel injected when the injector performs the first main fuel injection and when the injector performs the second main fuel injection is not less than the set value.
  • the rate of fuel injected between a main fuel injection and a second main fuel injection is less than a set value.
  • the controller can be connected with the control valve set on the fuel supply pipeline for the fuel injector, so as to control the fuel injection pressure of the fuel injector by controlling the control current of the control valve, and then adjust the fuel injector Efficiency of injected fuel.
  • the controller is used to determine the duration of the first main fuel injection and the first injection pressure, so that the cylinder pressure at least part of the time during the first main fuel injection can reach the cylinder pressure upper threshold. And the controller is used to iteratively adjust at least one of the duration of the second main fuel injection and the second injection pressure, so that during the second main fuel injection, the cylinder pressure drops from the cylinder pressure upper threshold to the set cylinder pressure During the time period, the change rate of the slope of the cylinder pressure change curve at each time point is within the set slope change rate range, and the cylinder pressure drops from the cylinder pressure upper threshold to the corresponding crankshaft within the time period of the set cylinder pressure.
  • the turned angle is not less than the first preset turning angle.
  • the fuel injector by controlling the fuel injector to perform main fuel injection twice during the movement cycle of the piston and continue auxiliary injection during the two main fuel injections, the high-speed oil jets of the two main fuel injections can be rolled up in the cylinder.
  • the superimposition of the spatial strength of the suction effect realizes the two-time organization of the oil beam to the flow field in the cylinder, strengthens the turbulent flow in the cylinder, improves the mixing rate of oil and gas in the cylinder, and effectively improves the combustion speed in the middle and late stages of combustion and the utilization rate of air in the cylinder.
  • the cylinder pressure can at least reach the upper threshold of the cylinder pressure, and during the second main fuel injection, the cylinder pressure drops from the upper threshold of the cylinder pressure to the set cylinder pressure
  • the rate of change of the slope of the cylinder pressure change curve at each time point is within the range of the set rate of change of the slope, and the angle at which the crankshaft rotates is not less than the first preset angle, which can ensure the space entrainment superposition effect Optimum, to ensure the optimal power output of the diesel engine.
  • This embodiment provides a diesel engine, which includes the combustion system in Embodiment 1. And the diesel engine has the beneficial effect of the combustion system in the first embodiment.
  • This embodiment provides a method for controlling a combustion system, which can be implemented by the combustion system in Embodiment 1.
  • the control methods of the combustion system include:
  • S100 Determine the duration of the first main fuel injection and the first injection pressure, so that the cylinder pressure at least part of the time during the first main fuel injection can reach the cylinder pressure upper threshold.
  • S200 Iteratively adjust at least one of the duration of the second main fuel injection and the second injection pressure, so that during the second main fuel injection, the cylinder pressure drops from the cylinder pressure upper limit threshold to the set cylinder pressure for a period of time
  • the change rate of the slope of the cylinder pressure change curve at each time point is within the range of the set slope change rate, and the corresponding crankshaft turns during the time period when the cylinder pressure drops from the cylinder pressure upper threshold to the set cylinder pressure.
  • the angle of is not smaller than the first preset rotation angle.
  • the control method of the combustion system can make the high-speed oil jets of the two main fuel injections in the cylinder
  • the superposition of the spatial intensity of the internal entrainment effect realizes the two organization of the oil beam to the flow field in the cylinder, strengthens the turbulent flow in the cylinder, improves the mixing rate of oil and gas in the cylinder, and effectively improves the combustion speed in the middle and late stages of combustion and the utilization rate of air in the cylinder;
  • it can also ensure that the superposition effect of space entrainment is optimal, and the power output of the diesel engine is optimal.
  • the cylinder pressure during the first main fuel injection if the cylinder pressure during the first main fuel injection has not reached the cylinder pressure upper limit threshold, iteratively adjust at least one of the start time, end time and current first injection pressure of the first main fuel injection.
  • the cylinder pressure during the process of the first main fuel injection reaches the cylinder pressure upper limit threshold at least part of the time, and when the cylinder pressure reaches the cylinder pressure upper limit threshold for the first time, the corresponding crank angle does not exceed the first angle, and the cylinder pressure changes from the first The angle that the crankshaft rotates during the period when the cylinder pressure rises to the cylinder pressure upper limit threshold is not less than the second preset rotation angle; wherein, the corresponding cylinder volume when the cylinder pressure is equal to the first cylinder pressure corresponds to the cylinder pressure reaching the cylinder pressure upper limit threshold for the first time The cylinder volume is the same. In this way, the closed-loop adjustment of the cylinder pressure during the first main fuel injection can be realized, and finally the cylinder pressure during the first main
  • the time when the injector starts the first main fuel injection is the first time t 1
  • the injector is between the first main fuel injection and the second main fuel injection
  • the time at which the injected fuel rate is the lowest is the second time t 2
  • the corresponding injection pressure when the injected fuel rate is the highest during the first main fuel injection process of the injector is the first injection pressure P 1 .
  • steps S10 to S30 after a limited number of piston movement cycles, it can be ensured that when the rotation angle of the crankshaft has not yet reached the first angle, the cylinder pressure will not be less than the cylinder pressure upper limit threshold P max , thereby increasing the combustion speed and In-cylinder air utilization.
  • the first angle is AI50, so the combustion system control method can effectively shorten the time from AI50 to AI90 and control the combustion rate to be stable at P max during the time period between AI50 and AI90.
  • the specific value of P max can be set according to actual needs.
  • the method of increasing the value of the first injection pressure P1, and/or reducing the overall difference between the second time t2 and the first time t1 is as follows:
  • the maximum value P x of the cylinder pressure during the first main fuel injection can be obtained from all the collected values of the cylinder pressure during the movement cycle of the piston, and P max >P x .
  • P max >P x .
  • n>5% increase the value of the first injection pressure P1 by the first set value, and at the same time adjust the first time t1 and/or the second time t2 so that the second time t2 is the same as the first
  • the difference in time t1 is overall reduced by the second set value.
  • the difference between P max and the maximum value P x of the cylinder pressure during the first main fuel injection is not much different, and it can be adjusted directly by adjusting the first Injection pressure P1 improves the injection rate of the oil beam, thereby improving the degree of oil-gas mixing and the flow field in the cylinder, and adjusting the cylinder pressure P in the cylinder and the crankshaft angle when the cylinder pressure P reaches P max ; when n>5%, There is a large difference between P max and the maximum value P x of the cylinder pressure during the first main fuel injection, so it is necessary to adjust the difference between the second time t2 and the first time t1 while adjusting the first injection pressure P1 Adjustment can also achieve the effect of improving the injection rate of the oil beam, and adjusting the cylinder pressure P in the cylinder and the crankshaft angle when the cylinder pressure P reaches P max .
  • the size of the first set value and the second set value can be set as required, and when adjusting the difference between the second time t2 and the first time t1 , only the second time can be adjusted as required t 2 or the first time t 1 are adjusted individually.
  • a scheme of adjusting the duration of the first main fuel injection and the first injection pressure through experience is given as an example, and in other embodiments, it can also be adjusted through a model.
  • obtaining the real-time volume in the cylinder is an existing technology, for example, the cylinder pressure curve of each cycle of the diesel engine can be collected by a combustion analyzer, and then the real-time volume in the cylinder can be obtained.
  • the acquired real-time cylinder volume V is the cylinder volume V when the cylinder pressure reaches P max for the first time during the first main fuel injection process.
  • step S80 Increase the value of the first injection pressure P1 by the third set value, and/or adjust the first time t1 and/or the second time t2 so that the second time t2 is the same as the first time t1
  • the overall difference is reduced by the fourth set value, and step S10 is repeated.
  • steps S40 to S80 the closed-loop adjustment of the crankshaft rotation angle during the period when the cylinder pressure rises from the first cylinder pressure to the cylinder pressure upper limit threshold can be realized, ensuring that after a limited number of piston movement cycles, ⁇
  • the value of 1 is not less than ⁇ n , which can ensure the optimal economic efficiency of the double main jet entrainment superposition effect.
  • the specific numerical value of ⁇ n , the third set value and the fourth set value can be set as required.
  • the second injection pressure is P 2 ; when ⁇ 1 ⁇ ⁇ n , in S200 “iteratively adjust at least one of the duration of the second main fuel injection and the second injection pressure, so that the second main fuel
  • the change rate of the slope of the cylinder pressure change curve at each time point is within the set slope change rate range, and the cylinder
  • the crankshaft turns at an angle not less than the first preset rotation angle
  • the cylinder pressure P corresponding to the crank angle between ⁇ b and ⁇ c is at least not less than P n , and it can be considered that the cylinder pressure is within the peak fluctuation.
  • the value of P n can be set as required.
  • k 1 is the slope of the curve y
  • k 2 is the rate of change of the slope of the curve.
  • the maximum value of the absolute value of k 2 refers to the value with the largest absolute value among the smallest negative value and the largest positive value of k 2 within the value range of ⁇ b to ⁇ c .
  • the specific numerical value of k a and the fifth set value can be set as required.
  • the value of k a is 0.05, and the corresponding setting slope change rate ranges from -0.05 to 0.05.
  • the minimum value of k 2 is not less than ka
  • the value of ka is greater than or equal to 0.05. It can be understood that by increasing the second injection pressure P 2 , the injection rail pressure can be increased to maintain the cylinder pressure near a constant value.
  • steps S90 to S140 the closed-loop adjustment of the rate of change of the slope of the cylinder pressure change curve at each time point during the period when the cylinder pressure drops from the upper threshold of the cylinder pressure to the set cylinder pressure is realized, which can ensure that the cylinder pressure can be adjusted within a limited number of times.
  • the minimum value of k 2 is not less than k a , which can ensure the optimal economy of the double main jet entrainment superimposed effect.
  • the time when the injector ends the second main fuel injection is the third time t 3 , if k max ⁇ k a , the following steps after step S130 are also included.
  • S170 Increase the value of the third time t3 by a sixth set value.
  • the size of the sixth set value and the size of the second preset rotation angle ⁇ m can be set according to needs, and through steps S150 to S180, the time period during which the cylinder pressure drops from the cylinder pressure upper limit threshold to the set cylinder pressure is realized
  • the closed-loop adjustment of the angle of the corresponding crankshaft inside can ensure that the value of ⁇ 2 is not less than ⁇ m after a limited number of reciprocating movements of the piston, thereby ensuring that the sum of ⁇ 1 + ⁇ 2 is large enough to make the dual main drive
  • the economy of superimposition effect of spray entrainment is optimal.

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  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)

Abstract

一种燃烧系统的控制方法、燃烧系统及柴油机，燃烧系统的控制方法通过两次主燃料喷射能够使两次喷射的油束于缸内卷吸效应的空间强度叠加，实现油束对缸内流场的两次组织，强化缸内湍流，提高缸内油气混合的速率，有效提升燃烧中后期的燃烧速度和缸内空气利用率；且通过确定第一主燃料喷射的持续时长和第一喷射压力，保证气缸压力至少能达到缸压上限阈值，在第二主燃料喷射时，气缸压力从缸压上限阈值下降至设定缸压的时间段内，缸压变化曲线在各时间点的曲线斜率的变化率均处于设定斜率变化率范围内，且使曲轴转过的角度不小于第一预设转角。

Description

一种燃烧系统的控制方法、燃烧系统及柴油机
本申请要求于2021年06月17日提交中国专利局、申请号为202110669915.1、发明名称为“一种燃烧系统的控制方法、燃烧系统及柴油机”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明涉及柴油机技术领域，尤其涉及一种燃烧系统的控制方法及、燃烧系统及柴油机。
背景技术
现有柴油机的燃烧组织方式主要以扩散燃烧为主，燃烧速度很大程度上受限于油气混合速度。此外，现阶段高压共轨柴油机都采用一次主燃料喷射，单次高压喷射的卷吸效应主要发生在雾化区域，在油束中段卷吸作用减弱，油气混合效果较差，且由于柴油机转速较高，对于四冲程柴油机，用于组织油气混合的时间非常短，单次喷射产生的射流和液滴在经历破碎雾化之后，很难及时在燃烧室内扩散与空气形成均匀混合气，从而限制燃烧过程快速进行，进一步限制了柴油机功率输出。
发明内容
本发明的目的在于：提供一种燃烧系统的控制方法及、燃烧系统及柴油机，以提升燃油喷射后与空气混合的均匀性。
一方面，本发明提供一种燃烧系统的控制方法，所述燃烧系统包括活塞、喷油器和气缸，所述活塞能于所述气缸内往复地上下运动，所述喷油器在所述活塞的每个运动周期中至少依次执行第一主燃料喷射和第二主燃料喷射，且所述喷油器在所述第一主燃料喷射至所述第二主燃料喷射的过程中持续喷油；所述喷油器执行所述第一主燃料喷射过程中喷油速率最高时对应的喷射压力为第一喷射压力，所述喷油器执行所述第二主燃料喷射过程中喷油速率最高时对应的喷射压力为第二喷射压力；
所述燃烧系统的控制方法包括：
确定所述第一主燃料喷射的持续时长和第一喷射压力，以使所述第一主燃料喷射的过程中的至少部分时刻的气缸压力能够达到缸压上限阈值；
迭代调整所述第二主燃料喷射的持续时长和所述第二喷射压力中的至少一项，以使所述第二主燃料喷射的过程中，所述气缸压力从所述缸压上限阈值下降至设定缸压的时间段内，缸压变化曲线在各个时间点的曲线斜率的变化率均处于设定斜率变化率范围内，且使所述气缸压力从所述缸压上限阈值下降至所述设定缸压的时间段内对应的曲轴转过的角度不小于第一预设转角。
作为燃烧系统的控制方法的优选技术方案，所述确定所述第一主燃料喷射的持续时长和第一喷射压力，以使所述第一主燃料喷射的过程中的至少部分时刻的气缸压力能够达到缸压上限阈值包括：
若所述第一主燃料喷射的过程中的气缸压力始终未达到缸压上限阈值，则迭代调整所述第一主燃料喷射的开始时间、结束时间和当前第一喷射压力中的至少一项，直至所述第一主燃料喷射的过程中的气缸压力至少部分时刻达到所述缸压上限阈值，且当所述气缸压力首次达到所述缸压上限阈值时对应的曲轴转角不超过第一角度，且所述气缸压力从第一气缸压力上升到所述缸压上限阈值的时间段内曲轴转过的角度不小于第二预设转角；其中，所述气缸压力等于所述第一气缸压力时对应的气缸容积与所述气缸压力首次达到所述缸压上限阈值对应的气缸容积相同。
作为燃烧系统的控制方法的优选技术方案，在活塞的每个运动周期中，喷油器开始第一主燃料喷射的时间为第一时间t 1，喷油器在第一主燃料喷射和第二主燃料喷射之间喷射的燃油的速率最低的时间为第二时间t 2，第一喷射压力为P 1；
所述若所述第一主燃料喷射的过程中的气缸压力始终未达到缸压上限阈值，则迭代调整所述第一主燃料喷射的开始时间、结束时间和当前第一喷射压力中的至少一项，直至所述第一主燃料喷射的过程中的气缸压力至少部分时刻达到所述缸压上限阈值，且当所述气缸压力首次达到所述缸压上限阈值时对应的曲轴转角不超过第一角度，且所述气缸压力从所述第一气缸压力上升到所述缸压上限阈值的时间段内曲轴转过的角度不小于第二预设转角包括：
第一主燃料喷射的过程中，实时采集气缸内的气缸压力P，实时采集曲轴 的转角，并将气缸压力P和缸压上限阈值P max比较，且判断曲轴的转角是否超过第一角度；
若气缸压力P小于缸压上限阈值P max，且曲轴的转角位于第一角度之后；则增大第一喷射压力P 1的数值；和/或，将第二时间t 2与第一时间t 1的差值整体减小。
作为燃烧系统的控制方法的优选技术方案，增大第一喷射压力P 1的数值；和/或，将第二时间t 2与第一时间t 1的差值整体减小包括：
获取第一主燃料喷射的过程中气缸压力的最大值P x；
计算n＝(P max－P x)/P max；
若n≤5％；则仅将第一喷射压力P 1的数值增大第一设定值。
作为燃烧系统的控制方法的优选技术方案，若n＞5％，则将第一喷射压力P 1的数值增大第一设定值，且调整第一时间t 1和/或第二时间t 2以使第二时间t 2与第一时间t 1的差值整体减小第二设定值。
作为燃烧系统的控制方法的优选技术方案，若气缸压力P不小于缸压上限阈值P max，且曲轴的转角位于第一角度之前；
获取气缸压力P等于缸压上限阈值P max时的气缸内的实时气缸容积V；
根据气缸容积和曲轴转角的关系map，获取气缸容积等于实时气缸容积V时所对应的气缸上行时的曲轴转角φ a和气缸下行时的曲轴转角φ b；
计算φ 1＝φ b－φ a；
判断φ 1与第二预设转角φ n的大小；
若φ 1＜φ n，则将第一喷射压力P 1的数值增大第三设定值，和/或调整第一时间t 1和/或第二时间t 2以使第二时间t 2与第一时间t 1的差值整体减小第四设定值。
作为燃烧系统的控制方法的优选技术方案，第二喷射压力为P 2；所述迭代调整所述第二主燃料喷射的持续时长和所述第二喷射压力中的至少一项，以使所述第二主燃料喷射的过程中，所述气缸压力从所述缸压上限阈值下降至设定缸压的时间段内，缸压变化曲线在各个时间点的曲线斜率的变化率均处于设定斜率变化率范围内，且使所述气缸压力从所述缸压上限阈值下降至所述设定缸压的时间段内对应的曲轴转过的角度不小于第一预设转角包括：
当φ 1≥φ n时；
根据map获取气缸压力P等于P n时的曲轴转角φ c，其中，φ c＞φ b，P n为设定缸压且P max＞P n；
获取曲轴转角φ b至曲轴转角φ c区间的气缸压力和曲轴转角间的关系曲线y；
计算k 1＝dy/dφ；k 2＝dk 1/dφ，φ的取值为φ c至φ d；
获取k 2的绝对值的最大值k max；
比较k max和预设参数k a的大小；
若k max＜k a，则将第二喷射压力P 2的数值增大第五设定值。
作为燃烧系统的控制方法的优选技术方案，喷油器结束第二主燃料喷射的时间为第三时间t 3，若k max≥k a，燃烧系统的控制方法还包括：
计算φ 2＝φ c–φ b；
判断φ 2与第一预设转角φ m的大小；
若φ 2＜φ m，则将第三时间t 3的数值增大第六设定值。
作为燃烧系统的控制方法的优选技术方案，若φ 2≥φ m，则保持第三时间t 3的数值不变。
另一方面，本发明提供一种燃烧系统，用于实施任意上述方案中所述的燃烧系统的控制方法，燃烧系统包括活塞、喷油器、气缸和控制器，所述控制器用于控制所述喷油器在所述活塞的每个运动周期中至少依次执行第一主燃料喷射和第二主燃料喷射，且所述喷油器在所述第一主燃料喷射至所述第二主燃料喷射的过程中持续喷油；
所述控制器用于确定所述第一主燃料喷射的持续时长和第一喷射压力，以使所述第一主燃料喷射的过程中的至少部分时刻的气缸压力能够达到缸压上限阈值；
所述控制器用于迭代调整所述第二主燃料喷射的持续时长和所述第二喷射压力中的至少一项，以使所述第二主燃料喷射的过程中，所述气缸压力从所述缸压上限阈值下降至设定缸压的时间段内，缸压变化曲线在各个时间点的曲线斜率的变化率均处于设定斜率变化率范围内，且使所述气缸压力从所述缸压上限阈值下降至所述设定缸压的时间段内对应的曲轴转过的角度不小于第一 预设转角。
再一方面，本发明提供一种柴油机，包括上述方案中的燃烧系统。
本发明的有益效果为：
本发明提供一种燃烧系统的控制方法、燃烧系统及柴油机，该燃烧系统的控制方法通过两次主燃料喷射能够使两次主燃料喷的高速油束于缸内卷吸效应的空间强度叠加，实现油束对缸内流场的两次组织，强化缸内湍流，提高缸内油气混合的速率，有效提升燃烧中后期的燃烧速度和缸内空气利用率；且通过确定第一主燃料喷射的持续时长和第一喷射压力保证气缸压力，以使第一主燃料喷射的过程中的至少部分时刻的气缸压力能够达到缸压上限阈值；迭代调整所述第二主燃料喷射的持续时长和所述第二喷射压力中的至少一项，以使所述第二主燃料喷射的过程中，所述气缸压力从所述缸压上限阈值下降至设定缸压的时间段内，缸压变化曲线在所述时间段内的各个时间点的曲线斜率的变化率均处于设定斜率变化率范围内，且使所述气缸压力从所述缸压上限阈值下降至所述设定缸压的时间段内对应的曲轴转过的角度不小于第一预设转角，能够保证空间卷吸叠加效应达到最优，保证柴油机功率输出最优。
附图说明
图1为本发明实施例二中喷油器的喷油规律示意图；
图2为本发明实施例二中瞬时放热率与曲轴转角的关系图；
图3为本发明实施例二中卷吸效应燃烧速率及缸压示功图。
具体实施方式
下面将结合附图对本发明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。
在本发明的描述中，需要说明的是，术语“中心”、“上”、“下”、“左”、“右”、“竖直”、“水平”、“内”、“外”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本发明和简化描述，而不是指示或暗 示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本发明的限制。此外，术语“第一”、“第二”、仅用于描述目的，而不能理解为指示或暗示相对重要性。其中，术语“第一位置”和“第二位置”为两个不同的位置，而且，第一特征在第二特征“之上”、“上方”和“上面”包括第一特征在第二特征正上方和斜上方，或仅仅表示第一特征水平高度高于第二特征。第一特征在第二特征“之下”、“下方”和“下面”包括第一特征在第二特征正下方和斜下方，或仅仅表示第一特征水平高度小于第二特征。
在本发明的描述中，需要说明的是，除非另有明确的规定和限定，术语“安装”、“相连”、“连接”应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或一体地连接；可以是机械连接，也可以是电连接；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通。对于本领域的普通技术人员而言，可以具体情况理解上述术语在本发明中的具体含义。
下面详细描述本发明的实施例，所述实施例的示例在附图中示出，其中自始至终相同或类似的标号表示相同或类似的元件或具有相同或类似功能的元件。下面通过参考附图描述的实施例是示例性的，仅用于解释本发明，而不能理解为对本发明的限制。
实施例一
本实施例提供一种燃烧控制系统，燃烧控制系统包括活塞、喷油器和气缸，其中，活塞能于气缸内往复地上下运动，喷油器用于将燃油喷射于设置于活塞的燃烧室内。该燃烧控制系统还包括控制器，控制器用于控制喷油器在活塞的每个运动周期中至少依次执行第一主燃料喷射和第二主燃料喷射，且喷油器在第一主燃料喷射至第二主燃料喷射的过程中持续喷油，且喷油器进行一主燃料喷射和喷油器进行第二主燃料喷射时喷射出的燃油的速率均不小于设定值，喷油器在第一主燃料喷射和第二主燃料喷射之间喷射出的燃油的速率小于设定值。其中，控制器可与设置于给喷油器供油的供油管路上的控制阀连接，以通过对控制阀控制电流大小的控制对喷油器的喷油压力进行控制，进而调节喷油器喷出的燃油的效率。
其中，控制器用于确定第一主燃料喷射的持续时长和第一喷射压力，以使第一主燃料喷射的过程中的至少部分时刻的气缸压力能够达到缸压上限阈值。 且控制器用于迭代调整第二主燃料喷射的持续时长和第二喷射压力中的至少一项，以使第二主燃料喷射的过程中，气缸压力从缸压上限阈值下降至设定缸压的时间段内，缸压变化曲线在各个时间点的曲线斜率的变化率均处于设定斜率变化率范围内，且使气缸压力从缸压上限阈值下降至设定缸压的时间段内对应的曲轴转过的角度不小于第一预设转角。控制器具体的实现过程详见下文。
本实施例中，通过控制喷油器在活塞的运动周期中两次进行主燃料喷射且在两次主燃料喷射过程中持续辅助喷射，能够使两次主燃料喷射的高速油束于缸内卷吸效应的空间强度叠加，实现油束对缸内流场的两次组织，强化缸内湍流，提高缸内油气混合的速率，有效提升燃烧中后期的燃烧速度和缸内空气利用率。且通过确定第一主燃料喷射的持续时长和第一喷射压力，保证气缸压力至少能达到缸压上限阈值，在第二主燃料喷射时，气缸压力从缸压上限阈值下降至设定缸压的时间段内，缸压变化曲线在各时间点的曲线斜率的变化率均处于设定斜率变化率范围内，且使曲轴转过的角度不小于第一预设转角，能够保证空间卷吸叠加效应最优，保证柴油机功率输出最优。
实施例二
本实施例提供一种柴油机，柴油机包括实施例一中的燃烧系统。且柴油机具有实施例一中的燃烧系统的有益效果。
实施例三
本实施例提供一种燃烧系统的控制方法，可通过实施例一中的燃烧系统实施。燃烧系统的控制方法包括：
S100：确定第一主燃料喷射的持续时长和第一喷射压力，以使第一主燃料喷射的过程中的至少部分时刻的气缸压力能够达到缸压上限阈值。
S200：迭代调整第二主燃料喷射的持续时长和第二喷射压力中的至少一项，以使第二主燃料喷射的过程中，气缸压力从缸压上限阈值下降至设定缸压的时间段内，缸压变化曲线在各个时间点的曲线斜率的变化率均处于设定斜率变化率范围内，且使气缸压力从缸压上限阈值下降至设定缸压的时间段内对应的曲轴转过的角度不小于第一预设转角。
该燃烧系统的控制方法，通过控制喷油器在活塞的运动周期中两次进行主燃料喷射且在两次主燃料喷射过程中持续辅助喷射，能够使两次主燃料喷射的 高速油束于缸内卷吸效应的空间强度叠加，实现油束对缸内流场的两次组织，强化缸内湍流，提高缸内油气混合的速率，有效提升燃烧中后期的燃烧速度和缸内空气利用率；同时还能够保证空间卷吸叠加效应达到最优，保证柴油机功率输出最优。
可选地，S100中，若第一主燃料喷射的过程中的气缸压力始终未达到缸压上限阈值，则迭代调整第一主燃料喷射的开始时间、结束时间和当前第一喷射压力中的至少一项，直至第一主燃料喷射的过程中的气缸压力至少部分时刻达到缸压上限阈值，且当气缸压力首次达到缸压上限阈值时对应的曲轴转角不超过第一角度，且气缸压力从第一气缸压力上升到缸压上限阈值的时间段内曲轴转过的角度不小于第二预设转角；其中，气缸压力等于第一气缸压力时对应的气缸容积与气缸压力首次达到缸压上限阈值对应的气缸容积相同。如此可实现对第一主燃料喷射的过程中的气缸压力的闭环调节，并最终使第一主燃料喷射的过程中的气缸压力达到缸压上限阈值。
如图1所示，在活塞的每个运动周期中，喷油器开始第一主燃料喷的时间为第一时间t 1，喷油器在第一主燃料喷和第二主燃料喷之间喷射的燃油的速率最低的时间为第二时间t 2，喷油器进行第一主燃料喷的过程中喷射的燃油的速率最高时对应的喷射压力为第一喷射压力P 1。
具体地，“若第一主燃料喷射的过程中的气缸压力始终未达到缸压上限阈值，则迭代调整第一主燃料喷射的开始时间、结束时间和当前第一喷射压力中的至少一项，直至第一主燃料喷射的过程中的气缸压力至少部分时刻达到缸压上限阈值，且当气缸压力首次达到缸压上限阈值时对应的曲轴转角不超过第一角度，且气缸压力从第一气缸压力上升到缸压上限阈值的时间段内曲轴转过的角度不小于第二预设转角”的方法为：
S10：第一主燃料喷射的过程中，实时采集缸内的气缸压力P，实时采集曲轴的转角。
S20：将气缸压力P和缸压上限阈值P max比较，且判断曲轴的转角是否超过第一角度。
若气缸压力P小于缸压上限阈值P max，且曲轴的转角位于第一角度之后，则执行S30。
S30：增大第一喷射压力P 1的数值，和/或者将第二时间t 2与第一时间t 1的差值整体减小，并重复进行S10。
通过步骤S10至步骤S30，可在有限的几个活塞运动周期后，保证曲轴的转角尚未达到第一角度时，气缸压力便可不小于缸压上限阈值P max，进而提升燃烧中后期的燃烧速度和缸内空气利用率。如图2所示，本实施例中，第一角度为AI50，从而该燃烧系统控制方法可有效缩短AI50至AI90的时间且在AI50至AI90之间的时间段内控制燃烧速率稳定在P max。其中，P max的具体数值可根据实际需要进行设置。
可选地，增大第一喷射压力P 1的数值，和/或者将第二时间t 2与第一时间t 1的差值整体减小的方法如下：
获取第一主燃料喷射的过程中气缸压力的最大值P x。
计算n＝(P max－P x)/P max。
若n≤5％；则仅将第一喷射压力P 1的数值增大第一设定值。
可以理解的是，可从活塞的运动周期中所有采集的气缸压力的数值中获取第一主燃料喷射的过程中气缸压力的最大值P x，且P max＞P x。以将第一喷射压力P 1的数值增大第一设定值为例，其含义为将当前的活塞往复上下运动的周期中的第一喷射压力P 1加上第一设定值并作为新的第一喷射压力P 1，且应用于下一个活塞运动周期。
若n＞5％，则将第一喷射压力P 1的数值增大第一设定值，且同时调整第一时间t 1和/或第二时间t 2以使第二时间t 2与第一时间t 1的差值整体减小第二设定值。
由于第一喷射压力P 1的大小不能无限增加，当n≤5％时，此时P max与第一主燃料喷射的过程中气缸压力的最大值P x相差不大，可直接通过调节第一喷射压力P 1改善油束的喷射速率，进而改善油气混合的程度和缸内流场，对缸内的气缸压力P以及气缸压力P达到P max时的曲轴角度进行调节；n＞5％时，P max与第一主燃料喷射的过程中气缸压力的最大值P x相差较大，需要在调节第一喷射压力P 1的同时，对第二时间t 2与第一时间t 1的差值进行调节，同样可实现改善油束的喷射速率，对缸内的气缸压力P以及气缸压力P达到P max时的曲轴角度进行调节的作用。其中，第一设定值和第二设定值的 大小可根据需要进行设定，在调节第二时间t 2与第一时间t 1的差值的时候，亦可根据需要仅对第二时间t 2或第一时间t 1进行单独调节。
本实施例中，示例性地给出了通过经验对第一主燃料喷射的持续时长和第一喷射压力进行调整的方案，在其他的实施例中，亦可通过模型对其进行调整。
可选地，S20中若气缸压力P大于等于缸压上限阈值P max，且曲轴的转角位于第一角度之前，包括位于S20以后的以下步骤。
S40：获取气缸压力P等于缸压上限阈值P max时的气缸内的实时气缸容积V。
具体地，获取气缸内的实时容积为现有技术，例如，可通过燃烧分析仪对柴油机每次循环的缸压曲线进行采集，进而获取气缸内的实时容积。获取的实时气缸容积V为第一主燃料喷射过程中，气缸压力首次达到P max时的气缸容积V。
S50：根据气缸容积和曲轴转角的关系map，获取气缸容积等于实时气缸容积V时所对应的气缸上行时的曲轴转角φ a和气缸下行时的曲轴转角φ b。
可以理解的是，随着活塞上行和下行，缸内的容积先减小后增大，从而，对应同一个实时容积，对应有活塞上行时曲轴转角的位置和活塞下行时曲轴转角的位置。如图3所示，本实施例中，气缸上行时曲轴转角φ a对应的第一气缸压力P的大小等于P 0，气缸下行时，当曲轴转角为φ b时，气缸压力P等于缸压上限阈值P max。其中，气缸容积和曲轴转角的关系map可通过前期大量试验获得，并预存于控制器中。
S60：计算φ 1＝φ b－φ a。
S70：判断φ 1与第二预设转角φ n的大小。
若φ 1＜φ n，则执行S80。
S80：将第一喷射压力P 1的数值增大第三设定值，和/或调整第一时间t 1和/或第二时间t 2以使第二时间t 2与第一时间t 1的差值整体减小第四设定值，并重复步骤S10。
通过步骤S40至S80，可实现对气缸压力从所述第一气缸压力上升到所述缸压上限阈值的时间段内曲轴转过的角度的闭环调整，保证在有限次的活塞运动周期后，φ 1的数值不小于φ n，进而可保证双主喷卷吸叠加作用的经济性 最优。其中，φ n的具体数值大小、第三设定值以及第四设定值可根据需要进行设置。
可选地，第二喷射压力为P 2；当φ 1≥φ n时，S200中“迭代调整第二主燃料喷射的持续时长和第二喷射压力中的至少一项，以使第二主燃料喷射的过程中，气缸压力从缸压上限阈值下降至设定缸压的时间段内，缸压变化曲线在各个时间点的曲线斜率的变化率均处于设定斜率变化率范围内，且使气缸压力从缸压上限阈值下降至设定缸压的时间段内对应的曲轴转过的角度不小于第一预设转角”具体包括位于S80之后的以下步骤：
S90：根据map获取气缸压力P等于P n时的曲轴转角φ c，其中，φ c＞φ b，P n为设定缸压且P max＞P n。
可以理解的是，由于，φ c＞φ b，对应曲轴转角为φ b至φ c之间的气缸压力P至少不小于P n，可认为气缸压力处于峰值波动内。其中，P n的值可根据需要进行设置。
S100：获取曲轴转角φ b至曲轴转角φ c区间的气缸压力和曲轴转角间的关系曲线y。具体地，气缸压力和曲轴转角间的关系曲线y中，自变量为曲轴转角，因变量为气缸压力。
S110：计算k 1＝dy/dφ；k 2＝dk 1/dφ，φ的取值为φ b至φ c。
其中，k 1为曲线y的斜率，k 2为曲线斜率的变化率。
S120：获取k 2的绝对值的最大值k max。
其中，k 2的绝对值的最大值是指在φ的取值范围φ b至φ c内，k 2的最小负值和最大正值中绝对值最大的数值。
S130：比较k max和预设参数k a的大小。
若k max＜k a，则执行S140。
S140：将第二喷射压力P 2的数值增大第五设定值，并重复步骤S10。
其中，k a的具体数值大小和第五设定值可根据需要进行设置。本实施例中，k a的数值为0.05，对应的设定斜率变化率范围为－0.05～0.05。当k 2的最小数值不小于k a时，k a的数值大于或等于0.05。可以理解的是，通过增大第二喷射压力P 2，可增加喷射轨压，将气缸压力维持在恒定的值附近。通过步骤S90至S140，实现对缸压变化曲线在气缸压力从缸压上限阈值下降至设 定缸压的时间段内各个时间点的曲线斜率的变化率的闭环调节，可保证在有限次的活塞运动周期过程后，k 2的最小数值不小于k a，进而可保证双主喷卷吸叠加作用的经济性最优。
可选地，喷油器结束第二主燃料喷的时间为第三时间t 3，若k max≥k a，还包括位于步骤S130之后的以下步骤。
S150：计算φ 2＝φ c–φ b。
S160：判断φ 2与第一预设转角φ m的大小。
若φ 2＜φ m，则执行S170；若φ 2≥φ m，则执行S180。
S170：将第三时间t 3的数值增大第六设定值。
S180：保持第三时间t 3的数值不变。
其中，第六设定值的大小和第二预设转角φ m的大小可根据需要进行设定，通过步骤S150至S180，实现对气缸压力从缸压上限阈值下降至设定缸压的时间段内对应的曲轴转过的角度的闭环调节，可保证在有限次的活塞往复运动过程后，φ 2的数值不小于φ m，进而可保证φ 1+φ 2的和足够大，以使双主喷卷吸叠加作用的经济性最优。
显然，本发明的上述实施例仅仅是为了清楚说明本发明所作的举例，而并非是对本发明的实施方式的限定。对于所属领域的普通技术人员来说，在上述说明的基础上还可以做出其它不同形式的变化或变动。这里无需也无法对所有的实施方式予以穷举。凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本发明的保护范围之内。

Claims (11)

  1. 一种燃烧系统的控制方法，所述燃烧系统包括活塞、喷油器和气缸，所述活塞能于所述气缸内往复地上下运动，其特征在于，所述喷油器在所述活塞的每个运动周期中至少依次执行第一主燃料喷射和第二主燃料喷射，且所述喷油器在所述第一主燃料喷射至所述第二主燃料喷射的过程中持续喷油；所述喷油器执行所述第一主燃料喷射过程中喷油速率最高时对应的喷射压力为第一喷射压力，所述喷油器执行所述第二主燃料喷射过程中喷油速率最高时对应的喷射压力为第二喷射压力；
    所述燃烧系统的控制方法包括：
    确定所述第一主燃料喷射的持续时长和第一喷射压力，以使所述第一主燃料喷射的过程中的至少部分时刻的气缸压力能够达到缸压上限阈值；
    迭代调整所述第二主燃料喷射的持续时长和所述第二喷射压力中的至少一项，以使所述第二主燃料喷射的过程中，所述气缸压力从所述缸压上限阈值下降至设定缸压的时间段内，缸压变化曲线在各个时间点的曲线斜率的变化率均处于设定斜率变化率范围内，且使所述气缸压力从所述缸压上限阈值下降至所述设定缸压的时间段内对应的曲轴转过的角度不小于第一预设转角。
  2. 根据权利要求1所述的燃烧系统的控制方法，其特征在于，所述确定所述第一主燃料喷射的持续时长和第一喷射压力，以使所述第一主燃料喷射的过程中的至少部分时刻的气缸压力能够达到缸压上限阈值包括：
    若所述第一主燃料喷射的过程中的气缸压力始终未达到缸压上限阈值，则迭代调整所述第一主燃料喷射的开始时间、结束时间和当前第一喷射压力中的至少一项，直至所述第一主燃料喷射的过程中的气缸压力至少部分时刻达到所述缸压上限阈值，且当所述气缸压力首次达到所述缸压上限阈值时对应的曲轴转角不超过第一角度，且所述气缸压力从第一气缸压力上升到所述缸压上限阈值的时间段内曲轴转过的角度不小于第二预设转角；其中，所述气缸压力等于所述第一气缸压力时对应的气缸容积与所述气缸压力首次达到所述缸压上限阈值对应的气缸容积相同。
  3. 根据权利要求2所述的燃烧系统的控制方法，其特征在于，在活塞的 每个运动周期中，喷油器开始第一主燃料喷射的时间为第一时间t 1，喷油器在第一主燃料喷射和第二主燃料喷射之间喷射的燃油的速率最低的时间为第二时间t 2，第一喷射压力为P 1；
    所述若所述第一主燃料喷射的过程中的气缸压力始终未达到缸压上限阈值，则迭代调整所述第一主燃料喷射的开始时间、结束时间和当前第一喷射压力中的至少一项，直至所述第一主燃料喷射的过程中的气缸压力至少部分时刻达到所述缸压上限阈值，且当所述气缸压力首次达到所述缸压上限阈值时对应的曲轴转角不超过第一角度，且所述气缸压力从所述第一气缸压力上升到所述缸压上限阈值的时间段内曲轴转过的角度不小于第二预设转角包括：
    第一主燃料喷射的过程中，实时采集气缸内的气缸压力P，实时采集曲轴的转角，并将气缸压力P和缸压上限阈值P max比较，且判断曲轴的转角是否超过第一角度；
    若气缸压力P小于缸压上限阈值P max，且曲轴的转角位于第一角度之后；则增大第一喷射压力P 1的数值；和/或，将第二时间t 2与第一时间t 1的差值整体减小。
  4. 根据权利要求3所述的燃烧系统的控制方法，其特征在于，增大第一喷射压力P 1的数值；和/或，将第二时间t 2与第一时间t 1的差值整体减小包括：
    获取第一主燃料喷射的过程中气缸压力的最大值P x；
    计算n＝(P max-P x)/P max；
    若n≤5％；则仅将第一喷射压力P 1的数值增大第一设定值。
  5. 根据权利要求4所述的燃烧系统的控制方法，其特征在于，若n＞5％，则将第一喷射压力P 1的数值增大第一设定值，且调整第一时间t 1和/或第二时间t 2以使第二时间t 2与第一时间t 1的差值整体减小第二设定值。
  6. 根据权利要求3所述的燃烧系统的控制方法，其特征在于，若气缸压力P不小于缸压上限阈值P max，且曲轴的转角位于第一角度之前；
    获取气缸压力P等于缸压上限阈值P max时的气缸内的实时气缸容积V；
    根据气缸容积和曲轴转角的关系map，获取气缸容积等于实时气缸容积V时所对应的气缸上行时的曲轴转角φ a和气缸下行时的曲轴转角φ b；
    计算φ 1＝φ b-φ a；
    判断φ 1与第二预设转角φ n的大小；
    若φ 1＜φ n，则将第一喷射压力P 1的数值增大第三设定值，和/或调整第一时间t 1和/或第二时间t 2以使第二时间t 2与第一时间t 1的差值整体减小第四设定值。
  7. 根据权利要求6所述的燃烧系统的控制方法，其特征在于，第二喷射压力为P 2；所述迭代调整所述第二主燃料喷射的持续时长和所述第二喷射压力中的至少一项，以使所述第二主燃料喷射的过程中，所述气缸压力从所述缸压上限阈值下降至设定缸压的时间段内，缸压变化曲线在各个时间点的曲线斜率的变化率均处于设定斜率变化率范围内，且使所述气缸压力从所述缸压上限阈值下降至所述设定缸压的时间段内对应的曲轴转过的角度不小于第一预设转角包括：
    当φ 1≥φ n时；
    根据map获取气缸压力P等于P n时的曲轴转角φ c，其中，φ c＞φ b，P n为设定缸压且P max＞P n；
    获取曲轴转角φ b至曲轴转角φ c区间的气缸压力和曲轴转角间的关系曲线y；
    计算k 1＝dy/dφ；k 2＝dk 1/dφ，φ的取值为φ b至φ c；
    获取k 2的绝对值的最大值k max；
    比较k max和预设参数k a的大小；
    若k max＜k a，则将第二喷射压力P 2的数值增大第五设定值。
  8. 根据权利要求7所述的燃烧系统的控制方法，其特征在于，喷油器结束第二主燃料喷射的时间为第三时间t 3，若k max≥k a，燃烧系统的控制方法还包括：
    计算φ 2＝φ c-φ b；
    判断φ 2与第一预设转角φ m的大小；
    若φ 2＜φ m，则将第三时间t 3的数值增大第六设定值。
  9. 根据权利要求8所述的燃烧系统的控制方法，其特征在于，若φ 2≥φ m，则保持第三时间t 3的数值不变。
  10. 一种燃烧系统，其特征在于，用于实施权利要求1-9任一项所述的燃烧系统的控制方法，燃烧系统包括活塞、喷油器、气缸和控制器，所述控制器用于控制所述喷油器在所述活塞的每个运动周期中至少依次执行第一主燃料喷射和第二主燃料喷射，且所述喷油器在所述第一主燃料喷射至所述第二主燃料喷射的过程中持续喷油；
    所述控制器用于确定所述第一主燃料喷射的持续时长和第一喷射压力，以使所述第一主燃料喷射的过程中的至少部分时刻的气缸压力能够达到缸压上限阈值；
    所述控制器用于迭代调整所述第二主燃料喷射的持续时长和所述第二喷射压力中的至少一项，以使所述第二主燃料喷射的过程中，所述气缸压力从所述缸压上限阈值下降至设定缸压的时间段内，缸压变化曲线在各个时间点的曲线斜率的变化率均处于设定斜率变化率范围内，且使所述气缸压力从所述缸压上限阈值下降至所述设定缸压的时间段内对应的曲轴转过的角度不小于第一预设转角。
  11. 一种柴油机，其特征在于包括权利要求10所述的燃烧系统。
PCT/CN2022/073116 2021-06-17 2022-01-21 一种燃烧系统的控制方法、燃烧系统及柴油机 WO2022262276A1 (zh)

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