CN113374583B - Exhaust valve control method and storage medium based on cold start exhaust heat management - Google Patents

Exhaust valve control method and storage medium based on cold start exhaust heat management Download PDF

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CN113374583B
CN113374583B CN202110640043.6A CN202110640043A CN113374583B CN 113374583 B CN113374583 B CN 113374583B CN 202110640043 A CN202110640043 A CN 202110640043A CN 113374583 B CN113374583 B CN 113374583B
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exhaust valve
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eevo
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CN113374583A (en
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楼狄明
唐远贽
谭丕强
胡志远
房亮
张允华
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Tongji University
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D13/00Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing
    • F02D13/02Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing during engine operation
    • F02D13/0242Variable control of the exhaust valves only
    • F02D13/0246Variable control of the exhaust valves only changing valve lift or valve lift and timing
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D2200/00Input parameters for engine control
    • F02D2200/02Input parameters for engine control the parameters being related to the engine
    • F02D2200/10Parameters related to the engine output, e.g. engine torque or engine speed
    • F02D2200/1002Output torque
    • F02D2200/1004Estimation of the output torque
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00Road transport of goods or passengers
    • Y02T10/10Internal combustion engine [ICE] based vehicles
    • Y02T10/12Improving ICE efficiencies

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Abstract

The invention relates to an exhaust valve control method and a storage medium based on cold start exhaust heat management, wherein the method is used for controlling an exhaust valve when the inlet temperature of a post-processing system is smaller than a preset temperature threshold, and comprises the following steps: obtaining an initial EEVO crankshaft wrap angle; determining the current working condition of the engine by using the position of the accelerator and the rotating speed of the engine, and increasing the early opening angle of the exhaust valve by using an EEVO strategy; calculating the predicted output torque of the engine in real time; obtaining a calibration output torque of the current working condition when the original exhaust valve row line strategy is used for controlling the exhaust valve; if the predicted output torque is lower than the calibrated output torque to a certain degree, the early opening angle of the exhaust valve is postponed, otherwise, the engine dynamic property is normal, and the EEVO strategy is continuously used for controlling the exhaust valve. Compared with the prior art, the invention can flexibly adjust the torque and temperature balance relation between the dynamic property and the exhaust heat management in the actual operation process of the engine, and can ensure that the dynamic property is not excessively reduced while the cold start exhaust temperature is improved to the maximum extent.

Description

一种基于冷启动排气热管理的排气门控制方法及存储介质Exhaust valve control method and storage medium based on cold start exhaust heat management

技术领域technical field

本发明涉及发动机排气控制领域,尤其是涉及一种基于冷启动排气热管理的排气门控制方法及存储介质。The invention relates to the field of engine exhaust control, in particular to an exhaust valve control method and storage medium based on cold start exhaust heat management.

背景技术Background technique

柴油机可变气门技术相较于固定的气门升程正时布置,是一项可以发挥出柴油机部分负荷下节能减排潜力的技术,尤其是基于全可变气门设计的柴油机进排气系统控制策略,可以进一步实现任意工况下的不同气门行线及进排气策略的最优化设计。Compared with the fixed valve lift timing arrangement, the variable valve technology of diesel engine is a technology that can exert the potential of energy saving and emission reduction of diesel engine under partial load, especially the control strategy of intake and exhaust system of diesel engine based on fully variable valve design, which can Further realize the optimal design of different valve lines and intake and exhaust strategies under any working conditions.

为了使尾气排放满足排放要求,需要在柴油机后布置尾气后处理系统,对尾气进行催化转化,使其符合排放法规。在柴油车尤其是商乘柴油车上,由于缺乏布置空间,后处理系统往往无法采用紧耦合设计,进入后处理系统前的排气温度达不到后处理系统的最佳催化转化温度的需求。因此,排气热管理的重要措施之一就是提高排气温度,利用尾气中的热量直接促进后处理系统的催化转化效率。In order to make the exhaust emissions meet the emission requirements, it is necessary to arrange an exhaust after-treatment system behind the diesel engine to carry out catalytic conversion of the exhaust gas to make it comply with emission regulations. In diesel vehicles, especially commercial diesel vehicles, due to the lack of layout space, the aftertreatment system often cannot adopt a tightly coupled design, and the exhaust gas temperature before entering the aftertreatment system cannot meet the requirements of the optimal catalytic conversion temperature of the aftertreatment system. Therefore, one of the important measures for exhaust heat management is to increase the exhaust temperature and use the heat in the exhaust gas to directly promote the catalytic conversion efficiency of the aftertreatment system.

EEVO排气门早开策略是一种柴油机排气热管理的重要气门控制策略,EEVO的早开程度与排温有直接关系,核心思想是早开排气门以使得排气温度较高,在发动机冷启动过程中往往通过EEVO策略保证排气温度。但在实际应用EEVO策略时,早开角度过大可能存在牺牲过多缸内膨胀做功,导致发动机动力性下降、运转不稳,目前缺乏针对该排气门控制策略的有效实时调控手段。The EEVO exhaust valve early opening strategy is an important valve control strategy for diesel engine exhaust heat management. The early opening degree of EEVO is directly related to the exhaust temperature. The core idea is to open the exhaust valve early to make the exhaust temperature higher. During the cold start of the engine, the exhaust gas temperature is often guaranteed through the EEVO strategy. However, in the actual application of the EEVO strategy, if the early opening angle is too large, too much expansion work in the cylinder may be sacrificed, resulting in a decrease in engine power and unstable operation. At present, there is a lack of effective real-time control means for this exhaust valve control strategy.

发明内容Contents of the invention

本发明的目的就是为了克服上述现有技术存在的缺陷而提供一种基于冷启动排气热管理的排气门控制方法及存储介质,在发动机冷启动过程中使用EEVO策略控制排气门,并实时计算预测输出转矩,如果预测输出转矩低于标定输出转矩一定程度,则认为发动机动力性不足,推迟排气门早开角度,可以灵活调整发动机实际运行过程中动力性及排气热管理之间的转矩、温度平衡关系,在最大可能提升冷启动排温的同时,保证动力性不过多下降。The object of the present invention is to provide an exhaust valve control method and storage medium based on cold start exhaust heat management in order to overcome the above-mentioned defects in the prior art, and use EEVO strategy to control the exhaust valve during engine cold start, and Calculate the predicted output torque in real time. If the predicted output torque is lower than the calibrated output torque to a certain extent, it is considered that the engine power is insufficient, and the early opening angle of the exhaust valve can be delayed to flexibly adjust the power performance and exhaust heat during the actual operation of the engine. Manage the torque and temperature balance relationship between them, while increasing the cold start exhaust temperature as much as possible, while ensuring that the power performance does not drop too much.

本发明的目的可以通过以下技术方案来实现:The purpose of the present invention can be achieved through the following technical solutions:

一种基于冷启动排气热管理的排气门控制方法,用于在后处理系统的入口温度小于预设置的温度阈值时控制排气门,包括以下步骤:An exhaust valve control method based on cold start exhaust thermal management, used for controlling the exhaust valve when the inlet temperature of the aftertreatment system is lower than a preset temperature threshold, comprising the following steps:

S1、获取初始EEVO曲轴包角

Figure GDA0003832620980000021
为基于原始排气门行线策略的排气包角
Figure GDA0003832620980000022
的排气门起动早开提前角度;S1. Obtain the initial EEVO crankshaft wrap angle
Figure GDA0003832620980000021
is the exhaust wrap angle based on the original exhaust valve alignment strategy
Figure GDA0003832620980000022
The exhaust valve starts to open early and advances the angle;

S2、获取发动机的当前工况,使用EEVO策略增大排气门早开角度;S2. Obtain the current working condition of the engine, and use the EEVO strategy to increase the early opening angle of the exhaust valve;

S3、计算当前工况下发动机的预测输出转矩T′tq,获取使用原始排气门行线策略控制排气门时发动机在当前工况下的标定输出转矩Ttq,λ的取值范围为(0,1),如果T′tq<(λ×Ttq),则预测输出转矩T′tq过低,发动机动力性不足,按照当前工况下预设置的最佳角度值推迟排气门早开角度,重复步骤S3,否则,发动机动力性正常,重复步骤S2。S3. Calculate the predicted output torque T′ tq of the engine under the current working condition, and obtain the calibrated output torque T tq of the engine under the current working condition when the original exhaust valve line strategy is used to control the exhaust valve, and the value range of λ is (0, 1), if T′ tq <(λ×T tq ), the predicted output torque T′ tq is too low, and the power of the engine is insufficient, and the exhaust will be delayed according to the preset optimal angle value under the current working condition If the door opens early, repeat step S3; otherwise, if the engine power is normal, repeat step S2.

进一步的,所述温度阈值是根据后处理系统中DOC的起燃温度设置的,当后处理系统的入口温度不小于温度阈值时,说明冷启动结束,使用原始排气门行线策略控制排气门。Further, the temperature threshold is set according to the light-off temperature of the DOC in the aftertreatment system. When the inlet temperature of the aftertreatment system is not less than the temperature threshold, it means that the cold start is over, and the original exhaust valve line strategy is used to control the exhaust gas. Door.

进一步的,预设置的温度阈值为200℃。Further, the preset temperature threshold is 200°C.

进一步的,步骤S2中,获取发动机的当前工况,通过对EEVO策略的MAP图查表得到当前工况的排气门早开角度。Further, in step S2, the current working condition of the engine is obtained, and the early exhaust valve opening angle of the current working condition is obtained by looking up the MAP map of the EEVO strategy.

更进一步的,EEVO策略的MAP图的获取方式为:在各种工况下使用EEVO策略控制排气门,记录各个工况下最佳的排气门早开角度,得到EEVO策略的MAP图。Furthermore, the MAP diagram of the EEVO strategy is obtained by: using the EEVO strategy to control the exhaust valve under various working conditions, recording the optimal early opening angle of the exhaust valve under each working condition, and obtaining the MAP diagram of the EEVO strategy.

进一步的,步骤S3中预测输出转矩T′tq的计算步骤如下:Further, the calculation steps of predicted output torque T′ tq in step S3 are as follows:

获取当前的油门位置和发动机转速,基于油门位置和发动机转速确定当前工况,获取工况-机械效率MAP图,基于当前工况查表得到当前的机械效率ηm,按照下式计算得到预测输出转矩T′tqObtain the current throttle position and engine speed, determine the current working condition based on the throttle position and engine speed, obtain the working condition-mechanical efficiency MAP map, obtain the current mechanical efficiency η m based on the current working condition, and calculate the predicted output according to the following formula Torque T′ tq :

Figure GDA0003832620980000023
Figure GDA0003832620980000023

其中,i表示发动机气缸数,P表示缸内压力,τ表示冲程数。Among them, i represents the number of cylinders of the engine, P represents the pressure in the cylinder, and τ represents the number of strokes.

进一步的,步骤S3中,获取当前的油门位置和发动机转速,基于油门位置和发动机转速确定当前工况,再通过对原始排气门行线策略的工况-转矩MAP图查表得到当前工况的标定输出转矩TtqFurther, in step S3, the current throttle position and engine speed are obtained, the current working condition is determined based on the throttle position and the engine speed, and the current working condition is obtained by looking up the working condition-torque MAP map of the original exhaust valve line strategy. The rated output torque T tq of the condition.

更进一步的,原始排气门行线策略的工况-转矩MAP图的获取方式为:使用原始排气门行线策略控制排气门,记录各个工况下的发动机输出转矩,得到原始排气门行线策略对应的工况-转矩MAP图。Furthermore, the way to obtain the operating condition-torque MAP diagram of the original exhaust valve alignment strategy is: use the original exhaust valve alignment strategy to control the exhaust valve, record the engine output torque under each operating condition, and obtain the original The operating condition-torque MAP diagram corresponding to the exhaust valve line strategy.

进一步的,步骤S3中,λ的取值为0.9。Further, in step S3, the value of λ is 0.9.

进一步的,步骤S3中,当前工况下预设置的最佳角度值是通过对EEVO标定MAP图查表得到的,EEVO标定MAP图的获取方式为:在不同的工况下,令(T′tq/Ttq)<λ,按照不同的角度值推迟排气门早开角度,得到不同工况所对应的最佳角度值,建立EEVO标定MAP图。Further, in step S3, the preset optimal angle value under the current working condition is obtained by looking up the EEVO calibration MAP map, and the way to obtain the EEVO calibration MAP map is: under different working conditions, let (T' tq /T tq )<λ, delay the early opening angle of the exhaust valve according to different angle values, obtain the best angle values corresponding to different working conditions, and establish the EEVO calibration MAP diagram.

一种计算机存储介质,其上存储有可执行的计算机程序,所述计算机程序被执行时实现如上所述的基于冷启动排气热管理的排气门控制方法。A computer storage medium, on which an executable computer program is stored. When the computer program is executed, the above exhaust valve control method based on cold start exhaust heat management is implemented.

与现有技术相比,本发明通过实时监测后处理系统的入口温度来开关冷启动气门控制,在发动机冷启动过程中使用EEVO策略控制排气门,并根据缸内压力和当前工况的机械效率实时计算预测输出转矩,如果预测输出转矩低于标定输出转矩一定程度,则认为EEVO策略导致发动机动力性不足,推迟EEVO策略下的排气门早开;本申请能够均衡发动机动力性和排气温度,可以灵活调整发动机实际运行过程中动力性及排气热管理之间的转矩、温度平衡关系,在最大可能提升冷启动排温的同时,保证动力性不过多下降。Compared with the prior art, the present invention switches the cold start valve control by monitoring the inlet temperature of the aftertreatment system in real time, and uses the EEVO strategy to control the exhaust valve during the engine cold start process, and according to the in-cylinder pressure and the mechanical The efficiency calculates the predicted output torque in real time. If the predicted output torque is lower than the calibrated output torque to a certain extent, it is considered that the EEVO strategy leads to insufficient engine power, and the early opening of the exhaust valve under the EEVO strategy is delayed; this application can balance the engine power and exhaust temperature, it is possible to flexibly adjust the torque and temperature balance relationship between the power performance and exhaust heat management during the actual operation of the engine, so as to maximize the possible increase in cold start exhaust temperature while ensuring that the power performance does not drop too much.

而且,本发明预先建立EEVO标定MAP图,通过测试确定各个工况下的最佳角度值,在实车控制时,如果发动机动力不足,就可以直接根据当前工况查表得到最佳角度值,速度快,并可以按照当前工况的最佳角度值推迟排气门早开角度,能够更加精准的调整排气门,平衡发动机动力性和排气温度。Moreover, the present invention pre-establishes the EEVO calibration map, and determines the optimal angle value under each working condition through testing. When the real vehicle is controlled, if the engine power is insufficient, the optimal angle value can be directly obtained by looking up the table according to the current working condition. The speed is fast, and the early opening angle of the exhaust valve can be delayed according to the optimal angle value of the current working condition, so that the exhaust valve can be adjusted more accurately, and the engine power and exhaust temperature can be balanced.

附图说明Description of drawings

图1为本发明的流程图。Fig. 1 is a flowchart of the present invention.

具体实施方式detailed description

下面结合附图和具体实施例对本发明进行详细说明。本实施例以本发明技术方案为前提进行实施,给出了详细的实施方式和具体的操作过程,但本发明的保护范围不限于下述的实施例。The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is carried out on the premise of the technical solution of the present invention, and detailed implementation and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

实施例1:Example 1:

通过设置在后处理系统入口的温度传感器实时监测后处理系统的入口温度,如果入口温度小于预设置的温度阈值,则使用本申请提供的一种基于冷启动排气热管理的排气门控制方法对排气门进行控制,如果入口温度不小于温度阈值,则冷启动结束,切换至原始排气门行线策略控制排气门。The inlet temperature of the aftertreatment system is monitored in real time by the temperature sensor installed at the inlet of the aftertreatment system. If the inlet temperature is lower than the preset temperature threshold, an exhaust valve control method based on cold start exhaust heat management provided by this application is used. The exhaust valve is controlled. If the inlet temperature is not less than the temperature threshold, the cold start ends, and the original exhaust valve line strategy is switched to control the exhaust valve.

一种基于冷启动排气热管理的排气门控制方法,用于在后处理系统的入口温度小于预设置的温度阈值时控制排气门,如图1所示,包括以下步骤:An exhaust valve control method based on cold start exhaust heat management, used to control the exhaust valve when the inlet temperature of the aftertreatment system is lower than a preset temperature threshold, as shown in Figure 1, comprising the following steps:

S1、获取初始EEVO曲轴包角

Figure GDA0003832620980000041
为基于原始排气门行线策略的排气包角
Figure GDA0003832620980000042
的排气门起动早开提前角度;S1. Obtain the initial EEVO crankshaft wrap angle
Figure GDA0003832620980000041
is the exhaust wrap angle based on the original exhaust valve alignment strategy
Figure GDA0003832620980000042
The exhaust valve starts to open early and advances the angle;

S2、获取发动机的当前工况,使用EEVO策略增大排气门早开角度;S2. Obtain the current working condition of the engine, and use the EEVO strategy to increase the early opening angle of the exhaust valve;

S3、计算当前工况下发动机的预测输出转矩T′tq,获取使用原始排气门行线策略控制排气门时发动机在当前工况下的标定输出转矩Ttq,λ的取值范围为(0,1),如果T′tq<(λ×Ttq),则预测输出转矩T′tq过低,发动机动力性不足,按照当前工况下预设置的最佳角度值推迟排气门早开角度,重复步骤S3,否则,发动机动力性正常,重复步骤S2。S3. Calculate the predicted output torque T′ tq of the engine under the current working condition, and obtain the calibrated output torque T tq of the engine under the current working condition when the original exhaust valve line strategy is used to control the exhaust valve, and the value range of λ is (0, 1), if T′ tq <(λ×T tq ), the predicted output torque T′ tq is too low, and the power of the engine is insufficient, and the exhaust will be delayed according to the preset optimal angle value under the current working condition If the door opens early, repeat step S3; otherwise, if the engine power is normal, repeat step S2.

一种计算机存储介质,其上存储有可执行的计算机程序,计算机程序被执行时实现如上的基于冷启动排气热管理的排气门控制方法。A computer storage medium, on which an executable computer program is stored. When the computer program is executed, the above exhaust valve control method based on cold start exhaust heat management is realized.

如图1所示,在实车控制时,发动机怠速起动,尾气温度不高,可以通过冷启动排气门控制策略来进气排气热管理,最大可能的提高排气温度。在冷启动过程中,可以通过闭环控制检测后处理系统的入口温度是否达到预设置的温度阈值,从而决定是否结束冷启动排气门控制。温度阈值是根据后处理系统中DOC的起燃温度设置的,本实施例中当后处理系统的入口温度上升到200℃后,结束冷启动排气门控制,回归原始排气门行线策略控制排气门。As shown in Figure 1, in the actual vehicle control, the engine starts at idle speed and the exhaust gas temperature is not high. The cold start exhaust valve control strategy can be used to manage the intake and exhaust heat to increase the exhaust temperature as much as possible. During the cold start process, the closed-loop control can be used to detect whether the inlet temperature of the aftertreatment system reaches a preset temperature threshold, so as to decide whether to end the cold start exhaust valve control. The temperature threshold is set according to the light-off temperature of the DOC in the aftertreatment system. In this embodiment, when the inlet temperature of the aftertreatment system rises to 200°C, the cold start exhaust valve control ends and the original exhaust valve line strategy control is returned. exhaust valve.

步骤S2中,通过油门位置传感器获取油门位置,获取发动机转速,结合油门位置和发动机转速确定发动机的当前工况,在此处不多加赘述,相关行业从业者可以理解。再通过对EEVO策略的MAP图查表得到当前工况的排气门早开角度,对全可变气门机构进行控制。EEVO策略的MAP图的获取方式为:在各种工况下使用EEVO策略控制排气门,记录各个工况下最佳的排气门早开角度,得到EEVO策略的MAP图。In step S2, the accelerator position is acquired through the accelerator position sensor, the engine speed is obtained, and the current working condition of the engine is determined by combining the accelerator position and the engine speed. I won't repeat it here, and practitioners in related industries can understand it. Then, the early opening angle of the exhaust valve in the current working condition is obtained by looking up the MAP chart of the EEVO strategy, and the fully variable valve mechanism is controlled. The MAP diagram of the EEVO strategy is obtained by: using the EEVO strategy to control the exhaust valve under various working conditions, recording the best early opening angle of the exhaust valve under each working condition, and obtaining the MAP diagram of the EEVO strategy.

步骤S3中预测输出转矩T′tq的计算步骤如下:The calculation steps of predicted output torque T′ tq in step S3 are as follows:

通过油门位置传感器获取油门位置,获取发动机转速,基于油门位置和发动机转速确定当前工况,基于当前工况,对工况-机械效率MAP图查表得到当前的机械效率ηm,按照下式计算得到预测输出转矩T′tqObtain the throttle position through the throttle position sensor, obtain the engine speed, determine the current working condition based on the throttle position and the engine speed, and based on the current working condition, look up the working condition-mechanical efficiency MAP map to obtain the current mechanical efficiency η m , and calculate according to the following formula Get the predicted output torque T′ tq :

Figure GDA0003832620980000051
Figure GDA0003832620980000051

Figure GDA0003832620980000052
Figure GDA0003832620980000052

Figure GDA0003832620980000053
Figure GDA0003832620980000053

其中,Pmi表示平均指示压力,P表示缸内压力,P可以通过安装在发动机缸内的压力传感器实时获取,Vs发动机的气缸容积,dV表示发动机气缸容积的微分,n表示发动机转速,i表示发动机气缸数,τ表示冲程数,本实施例中发动机为四冲程发动机,τ的值为4。工况-机械效率MAP图的获取方式为:记录发动机不同工况下的机械效率,得到工况-机械效率MAP图,在此处不多加赘述,相关行业从业者可以理解。Among them, P mi represents the average indicated pressure, P represents the pressure in the cylinder, P can be obtained in real time through the pressure sensor installed in the engine cylinder, V s the cylinder volume of the engine, dV represents the differential of the engine cylinder volume, n represents the engine speed, i Indicates the number of cylinders of the engine, and τ indicates the number of strokes. In this embodiment, the engine is a four-stroke engine, and the value of τ is 4. The way to obtain the operating condition-mechanical efficiency MAP is: record the mechanical efficiency of the engine under different operating conditions, and obtain the operating condition-mechanical efficiency MAP. I will not repeat it here, and practitioners in related industries can understand it.

因此,在实车控制时,根据当前工况查表确定机械效率ηm的值,再将获取的实时缸内压力P和机械效率ηm代入计算,即可得到预测输出转矩T′tqTherefore, in the actual vehicle control, the value of mechanical efficiency η m is determined according to the current working condition, and then the obtained real-time cylinder pressure P and mechanical efficiency η m are substituted into the calculation to obtain the predicted output torque T′ tq .

缸内压力是与发动机的一个循环对应的,预测输出转矩的计算是与发动机的一个循环相对应的,本申请每经过一个发动机循环后计算一次预测输出转矩,并将预测输出转矩与当前工况的标定输出转矩进行比较,以判断是否需要在EEVO策略下推迟排气门早开角度。The pressure in the cylinder corresponds to one cycle of the engine, and the calculation of the predicted output torque corresponds to one cycle of the engine. This application calculates the predicted output torque after each cycle of the engine, and compares the predicted output torque with The calibrated output torque of the current working condition is compared to determine whether it is necessary to delay the early opening angle of the exhaust valve under the EEVO strategy.

步骤S3中获取当前的油门位置和发动机转速,基于油门位置和发动机转速确定当前工况,再通过对原始排气门行线策略的工况-转矩MAP图查表得到当前工况的标定输出转矩Ttq。原始排气门行线策略的工况-转矩MAP图的获取方式为:使用原始排气门行线策略控制排气门,记录各个工况下的发动机输出转矩,得到原始排气门行线策略对应的工况-转矩MAP图。In step S3, the current throttle position and engine speed are obtained, the current working condition is determined based on the throttle position and engine speed, and then the calibration output of the current working condition is obtained by looking up the working condition-torque MAP map of the original exhaust valve line strategy Torque T tq . The working condition-torque MAP diagram of the original exhaust valve alignment strategy is obtained by using the original exhaust valve alignment strategy to control the exhaust valve, recording the engine output torque under each working condition, and obtaining the original exhaust valve alignment The operating condition-torque MAP diagram corresponding to the line strategy.

由于使用EEVO策略,排气门早开,会影响发动机的动力性,即输出转矩减小,而标定输出转矩Ttq是不使用EEVO策略时发动机原定的输出转矩。因此,结合缸内压力和当前工况的机械效率计算当前的预测输出转矩,对比预测输出转矩和标定输出转矩以判断发动机动力性的下降程度。Because the EEVO strategy is used, the exhaust valve is opened early, which will affect the power of the engine, that is, the output torque is reduced, and the calibrated output torque T tq is the original output torque of the engine when the EEVO strategy is not used. Therefore, the current predicted output torque is calculated based on the in-cylinder pressure and the mechanical efficiency of the current working condition, and the predicted output torque is compared with the calibrated output torque to determine the degree of decline in engine power.

步骤S3中,λ的取值为0.9,即T′tq<90%×Ttq时认为发动机动力不足。事实上,EEVO策略为了保证排气温度较高,早开排气门,增大排气门早开角度,减少了发动机缸内膨胀做功,无疑会降低发动机的动力性。为了保证发动机的动力性不会过度降低,本申请设置了90%的阈值,在实车控制时,以使用原始排气门行线策略控制排气门时当前工况的发动机输出转矩Ttq为基准,当T′tq≥90%×Ttq时认为发动机动力性正常,保持当前EEVO包角范围,继续使用EEVO策略控制排气门,否则,认为EEVO策略下的排气门早开影响了发动机的动力性,推迟排气门早开角度。In step S3, the value of λ is 0.9, that is, when T′ tq <90%×T tq , it is considered that the engine power is insufficient. In fact, in order to ensure a high exhaust temperature, the EEVO strategy opens the exhaust valve early, increases the early opening angle of the exhaust valve, and reduces the expansion work in the engine cylinder, which will undoubtedly reduce the power of the engine. In order to ensure that the power of the engine will not be excessively reduced, this application sets a threshold of 90%. In the actual vehicle control, the engine output torque T tq of the current working condition when the original exhaust valve line strategy is used to control the exhaust valve As a benchmark, when T′ tq ≥ 90%×T tq , it is considered that the engine power is normal, keep the current EEVO wrap angle range, and continue to use the EEVO strategy to control the exhaust valve, otherwise, it is considered that the early opening of the exhaust valve under the EEVO strategy affects The dynamic performance of the engine delays the early opening angle of the exhaust valve.

步骤S3中,按照当前工况下预设置的最佳角度值推迟排气门早开角度,当前工况下预设置的最佳角度值是通过对EEVO标定MAP图查表得到的。每推迟一定的角度会对发动机的性能产生一定的影响,因此针对特定的发动机产品,首先进行基础实验测试,在不同的工况下,令(T′tq/Ttq)<λ,按照不同的角度值推迟排气门早开角度,记录该发动机的性能变化,从而得到该发动机的不同工况所对应的最佳角度值,得到该发动机的EEVO标定MAP图,在此处不多加赘述,相关行业从业者可以理解。In step S3, the early opening angle of the exhaust valve is delayed according to the preset optimal angle value under the current working condition. The preset optimal angle value under the current working condition is obtained by looking up the EEVO calibration MAP map. Every delay of a certain angle will have a certain impact on the performance of the engine. Therefore, for a specific engine product, the basic experimental test is first carried out. Under different working conditions, (T′ tq /T tq )<λ, according to different The angle value delays the early opening angle of the exhaust valve, and records the performance changes of the engine, so as to obtain the optimal angle value corresponding to the different working conditions of the engine, and obtain the EEVO calibration map of the engine. I will not repeat it here. Industry practitioners can understand.

实车控制时通过查表即确定每个工况的最佳角度值,并在一次循环中按照最佳角度值推迟排气门早开角度,在此处不多加赘述,相关行业从业者可以理解。The optimal angle value of each working condition is determined by looking up the table during real vehicle control, and the early opening angle of the exhaust valve is delayed according to the optimal angle value in one cycle. I won’t go into details here, and practitioners in related industries can understand .

推迟排气门早开角度后,实时获取缸内压力计算预测输出转矩T′tq,如果发动机的动力性仍然不足,即T′tq<90%×Ttq,则继续推迟排气门早开角度,否则,按照EEVO策略控制排气门早开。After delaying the early opening angle of the exhaust valve, obtain the in-cylinder pressure in real time to calculate the predicted output torque T′ tq , if the power of the engine is still insufficient, that is, T′ tq <90%×T tq , continue to delay the early opening of the exhaust valve Angle, otherwise, the early opening of the exhaust valve is controlled according to the EEVO strategy.

在上述排气门控制过程中,通过闭环控制实时监测后处理系统的入口温度,如果入口温度达到200℃,则结束冷启动EEVO控制,使用原始排气门行线策略控制排气门。In the above exhaust valve control process, the inlet temperature of the aftertreatment system is monitored in real time through closed-loop control. If the inlet temperature reaches 200 °C, the cold start EEVO control is ended, and the original exhaust valve line strategy is used to control the exhaust valve.

柴油机可变气门技术相较于固定的气门升程正时布置,是一项可以发挥出柴油机部分负荷下节能减排潜力的技术,尤其是基于全可变气门设计的柴油机进排气系统控制策略,在未来柴油机上有望全面搭载,而基于EEVO的排气热管理由于存在待解决的动力性与排温提升的平衡关系,需要核心控制技术来对当前EEVO策略进行调整。Compared with the fixed valve lift timing arrangement, the variable valve technology of diesel engine is a technology that can exert the potential of energy saving and emission reduction of diesel engine under partial load, especially the control strategy of intake and exhaust system of diesel engine based on fully variable valve design. It is expected to be fully installed on diesel engines in the future, and the exhaust heat management based on EEVO needs core control technology to adjust the current EEVO strategy due to the unresolved balance between power and exhaust temperature.

本发明在发动机冷启动过程中使用EEVO策略控制排气门,并根据缸内压力实时计算预测输出转矩,如果预测输出转矩低于标定输出转矩一定程度,则认为发动机动力性不足,推迟排气门早开角度,可以灵活调整发动机实际运行过程中动力性及排气热管理之间的转矩、温度平衡关系,在最大可能提升冷启动排温的同时,保证动力性不过多下降,因此,市场应用前景较为广泛。The invention uses the EEVO strategy to control the exhaust valve during the cold start of the engine, and calculates the predicted output torque in real time according to the pressure in the cylinder. If the predicted output torque is lower than the calibrated output torque to a certain extent, it is considered that the engine power is insufficient, and the engine is delayed. The early opening angle of the exhaust valve can flexibly adjust the torque and temperature balance relationship between the power performance and the exhaust heat management during the actual operation of the engine. While increasing the cold start exhaust temperature as much as possible, it can ensure that the power performance does not drop too much. Therefore, the market application prospect is relatively broad.

以上详细描述了本发明的较佳具体实施例。应当理解,本领域的普通技术人员无需创造性劳动就可以根据本发明的构思作出诸多修改和变化。因此,凡本技术领域中技术人员依本发明的构思在现有技术的基础上通过逻辑分析、推理或者有限的实验可以得到的技术方案,皆应在由权利要求书所确定的保护范围内。The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make many modifications and changes according to the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art shall be within the scope of protection defined by the claims.

Claims (10)

1.一种基于冷启动排气热管理的排气门控制方法,其特征在于,用于在后处理系统的入口温度小于预设置的温度阈值时控制排气门,包括以下步骤:1. An exhaust valve control method based on cold-start exhaust heat management, characterized in that it is used to control the exhaust valve when the inlet temperature of the aftertreatment system is less than a preset temperature threshold, comprising the following steps: S1、获取初始EEVO曲轴包角
Figure FDA0003869411780000011
Figure FDA0003869411780000014
为基于原始排气门行线策略的排气包角
Figure FDA0003869411780000012
的排气门起动早开提前角度;
S1. Obtain the initial EEVO crankshaft wrap angle
Figure FDA0003869411780000011
Figure FDA0003869411780000014
is the exhaust wrap angle based on the original exhaust valve alignment strategy
Figure FDA0003869411780000012
The exhaust valve starts to open early and advances the angle;
S2、获取发动机的当前工况,使用EEVO策略增大排气门早开角度;S2. Obtain the current working condition of the engine, and use the EEVO strategy to increase the early opening angle of the exhaust valve; S3、计算当前工况下发动机的预测输出转矩T′tq,获取使用原始排气门行线策略控制排气门时发动机在当前工况下的标定输出转矩Ttq,λ的取值范围为(0,1),如果T′tq<(λ×Ttq),则按照当前工况下预设置的最佳角度值推迟排气门早开角度,重复步骤S3,否则,发动机动力性正常,重复步骤S2。S3. Calculate the predicted output torque T′ tq of the engine under the current working condition, and obtain the calibrated output torque T tq of the engine under the current working condition when the original exhaust valve line strategy is used to control the exhaust valve, and the value range of λ is (0, 1), if T′ tq <(λ×T tq ), delay the early opening angle of the exhaust valve according to the preset optimal angle value under the current working condition, and repeat step S3; otherwise, the engine power is normal , repeat step S2.
2.根据权利要求1所述的一种基于冷启动排气热管理的排气门控制方法,其特征在于,所述温度阈值是根据后处理系统中DOC的起燃温度设置的。2 . The exhaust valve control method based on cold start exhaust heat management according to claim 1 , wherein the temperature threshold is set according to the light-off temperature of the DOC in the aftertreatment system. 3 . 3.根据权利要求1所述的一种基于冷启动排气热管理的排气门控制方法,其特征在于,步骤S2中,获取当前的油门位置和发动机转速,基于油门位置和发动机转速确定当前工况,通过对EEVO策略的MAP图查表得到当前工况的排气门早开角度。3. The exhaust valve control method based on cold start exhaust heat management according to claim 1, characterized in that in step S2, the current throttle position and engine speed are obtained, and the current throttle position and engine speed are determined based on the throttle position and engine speed. For working conditions, the exhaust valve early opening angle of the current working condition is obtained by looking up the MAP chart of the EEVO strategy. 4.根据权利要求3所述的一种基于冷启动排气热管理的排气门控制方法,其特征在于,EEVO策略的MAP图的获取方式为:在各种工况下使用EEVO策略控制排气门,记录各个工况下最佳的排气门早开角度,得到EEVO策略的MAP图。4. The exhaust valve control method based on cold start exhaust heat management according to claim 3, wherein the method of obtaining the MAP map of the EEVO strategy is: using the EEVO strategy to control the exhaust valve under various working conditions. Valve, record the best exhaust valve early opening angle under each working condition, and get the MAP map of the EEVO strategy. 5.根据权利要求1所述的一种基于冷启动排气热管理的排气门控制方法,其特征在于,步骤S3中预测输出转矩T′tq的计算步骤如下:5. The exhaust valve control method based on cold start exhaust heat management according to claim 1, characterized in that the calculation steps of the predicted output torque T′ tq in step S3 are as follows: 获取当前的油门位置和发动机转速,基于油门位置和发动机转速确定当前工况,获取工况-机械效率MAP图,基于当前工况查表得到当前的机械效率ηm,获取发动机的缸内压力,按照下式计算得到预测输出转矩T′tqObtain the current throttle position and engine speed, determine the current working condition based on the throttle position and engine speed, obtain the working condition-mechanical efficiency MAP map, obtain the current mechanical efficiency η m based on the current working condition look-up table, and obtain the engine cylinder pressure, The predicted output torque T′ tq is calculated according to the following formula:
Figure FDA0003869411780000013
Figure FDA0003869411780000013
其中,i表示发动机气缸数,P表示缸内压力,dV表示发动机气缸容积的微分,τ表示冲程数。Among them, i represents the number of cylinders of the engine, P represents the pressure in the cylinder, dV represents the differential of the cylinder volume of the engine, and τ represents the number of strokes.
6.根据权利要求1所述的一种基于冷启动排气热管理的排气门控制方法,其特征在于,步骤S3中,获取当前的油门位置和发动机转速,基于油门位置和发动机转速确定当前工况,再通过对原始排气门行线策略的工况-转矩MAP图查表得到当前工况的标定输出转矩Ttq6. The exhaust valve control method based on cold start exhaust heat management according to claim 1, characterized in that in step S3, the current throttle position and engine speed are obtained, and the current throttle position and engine speed are determined based on the throttle position and engine speed. working condition, and then obtain the calibrated output torque T tq of the current working condition by looking up the working condition-torque MAP map of the original exhaust valve alignment strategy. 7.根据权利要求6所述的一种基于冷启动排气热管理的排气门控制方法,其特征在于,原始排气门行线策略的工况-转矩MAP图的获取方式为:使用原始排气门行线策略控制排气门,记录各个工况下的发动机输出转矩,得到原始排气门行线策略对应的工况-转矩MAP图。7. The exhaust valve control method based on cold start exhaust heat management according to claim 6, characterized in that, the way of obtaining the operating condition-torque MAP diagram of the original exhaust valve alignment strategy is: using The original exhaust valve alignment strategy controls the exhaust valve, records the engine output torque under each working condition, and obtains the operating condition-torque MAP diagram corresponding to the original exhaust valve alignment strategy. 8.根据权利要求1所述的一种基于冷启动排气热管理的排气门控制方法,其特征在于,步骤S3中,λ的取值为0.9。8 . The exhaust valve control method based on cold start exhaust heat management according to claim 1 , wherein in step S3 , the value of λ is 0.9. 9.根据权利要求1所述的一种基于冷启动排气热管理的排气门控制方法,其特征在于,步骤S3中,当前工况下预设置的最佳角度值是通过对EEVO标定MAP图查表得到的,EEVO标定MAP图的获取方式为:在不同的工况下,令(T′tq/Ttq)<λ,按照不同的角度值推迟排气门早开角度,得到不同工况所对应的最佳角度值,建立EEVO标定MAP图。9. The exhaust valve control method based on cold start exhaust thermal management according to claim 1, characterized in that in step S3, the preset optimal angle value under the current working condition is obtained by calibrating MAP for EEVO The way to obtain the EEVO calibration MAP map obtained by looking up the table is: under different working conditions, set (T′ tq /T tq )<λ, delay the early opening angle of the exhaust valve according to different angle values, and obtain different working conditions. The optimal angle value corresponding to the condition is used to establish the EEVO calibration map. 10.一种计算机存储介质,其上存储有可执行的计算机程序,其特征在于,所述计算机程序被执行时实现如权利要求1-9中任一所述的排气门控制方法。10. A computer storage medium, on which an executable computer program is stored, wherein the exhaust valve control method according to any one of claims 1-9 is realized when the computer program is executed.
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