阅读说明：本技术 一种基于模型的用于amt换挡的发动机转速控制方法 (model-based engine speed control method for AMT gear shifting ) 是由 周鹏 张建锐 张正兴 于 2019-09-04 设计创作，主要内容包括：本发明涉及一种基于模型的用于AMT换挡的发动机转速控制方法,属于换挡控制策略开发技术领域,其包括以下步骤：在发动机断油减速或者增油加速时,首先做发动机包括执行器的万有特性试验和瞬态特性试验；基于以上试验做出气路平均值模型以及发动机动力学模型；基于试验数据分析标定出排气节流阀关闭的最佳开度并制作最佳开度MAP表；然后建立一个观测器；根据Bang-Bang原理计算制动阀的开关面,建立代数函数使得发动机达到目标转速用时最短,同时在达到稳定时转速加速度在给定范围内；计算排气节流阀全开时维持发动机在目标转速下维持稳定的喷油量,以此为喷油量计算的前馈值,并通过喷油反馈调节转速。本发明可以精确的控制发动机转速,达到迅速换挡的目的。(The invention relates to a model-based engine speed control method for AMT gear shifting, which belongs to the technical field of gear shifting control strategy development and comprises the following steps: when the engine is in oil-cut deceleration or oil-increasing acceleration, firstly, universal characteristic tests and transient characteristic tests of the engine including an actuator are carried out; making a gas path average value model and an engine dynamics model based on the tests; analyzing and calibrating the optimal opening of the exhaust throttle valve based on the test data and making an optimal opening MAP table; then establishing an observer; calculating the switch surface of the brake valve according to the Bang-Bang principle, and establishing an algebraic function to ensure that the time for the engine to reach the target rotating speed is shortest, and the rotating speed acceleration is in a given range when the engine is stable; and calculating the fuel injection quantity for maintaining the engine to be stable at the target rotating speed when the exhaust throttle valve is fully opened, taking the fuel injection quantity as a feedforward value calculated by the fuel injection quantity, and adjusting the rotating speed through fuel injection feedback. The invention can accurately control the rotating speed of the engine and achieve the purpose of rapid gear shifting.)

1. A model-based engine speed control method for AMT shifting, comprising the steps of:

firstly, an engine universal characteristic test and a transient characteristic test are carried out when the engine is in oil-cut deceleration or oil-increasing acceleration, wherein the universal characteristic test comprises the universal characteristic of an actuator;

making a gas path average value model and an engine dynamics model based on the tests;

Analyzing and calibrating the optimal opening of the exhaust throttle valve to be closed based on the test data, and manufacturing an optimal opening MAP table of the exhaust throttle valve;

Establishing an observer by combining intake manifold pressure and air flow sensor values with an average value model;

calculating the switch surface of the brake valve according to the Bang-Bang principle, and establishing an algebraic function to ensure that the time for the engine to reach the target rotating speed is shortest, and the rotating speed acceleration is in a given range when the engine is stable;

and calculating the fuel injection quantity for maintaining the engine to be stable at the target rotating speed when the exhaust throttle valve is fully opened, taking the fuel injection quantity as a feedforward value calculated by the fuel injection quantity, and adjusting the rotating speed through fuel injection feedback.

2. A model-based engine speed control method for AMT shifting according to claim 1, wherein the calculation formula of the mean value model is:

imep＝f₂(n,θ_exthrottle,T_im,P_im,P_ex,θ_EGR,θ_VGT,P_amb)

fmep＝f₃(imep,n,T_engine)

when the engine is cut off, the exhaust throttle valve quickly reaches the minimum value, the minimum value is obtained through calibration, and the exhaust throttle valve is quickly opened again after a period of time, and finally the aim is to calculate the maximum and minimum opening and closing surfaces, namely the closing duration of the throttle valve;

Wherein n is the engine speed, theta_exthrottleFor waste gas throttle opening, T_imIs the intake manifold temperature, P_imIs intake manifold pressure, P_exIs the exhaust manifold pressure, θ_EGRIs EGR opening degree, θ_VGTIs the VGT opening degree, P_ambat ambient pressure, T_engineWater temperature, V_sIs the engine displacement.

3. A model-based engine speed control method for an AMT shift as set forth in claim 2 wherein said mean value modeling is used to calculate transient values, dynamic values for cylinder intake and exhaust manifold pressures, which reflect a direct relationship of valve actuation to IMEP by simplification, but with MAP and sensor values as initial inputs, are obtained.

4. a model-based engine speed control method for an AMT shift according to claim 2 wherein a cost function is established to minimize the time for the engine to reach a target speed after the exhaust throttle valve is closed and opened, and wherein the engine speed acceleration is less than a calibrated value when the target is reached.

5. The model-based engine speed control method for AMT shift according to claim 1, wherein the observer is established by combining intake manifold pressure and air flow sensor values with an average value model, and calculates the time required for the engine speed to reach the target opening/closing surface speed under the initial condition of intake manifold pressure at the moment of fuel cut, and the time required for the engine speed to reach the target value after the throttle is fully opened, and establishes a cost function to minimize the sum of two periods of time, and at the same time, there is a constraint on the engine speed acceleration when the target speed is reached; thereafter, the accuracy is ensured by injection closed-loop control.

Technical Field

The invention belongs to the technical field of gear shifting control strategy development, and particularly relates to a method for controlling the rotating speed of an engine of a heavy diesel vehicle.

background

An electric control mechanical automatic transmission for automobiles is characterized in that an automatic gear shifting system is additionally arranged on the basis of a traditional fixed shaft transmission (MT), and a transmission control unit is adopted to control an actuating mechanism. Compared with other automatic transmission systems, the automatic transmission system has the advantages of high transmission efficiency, low manufacturing cost, mature process flow, easiness in manufacturing and the like. However, the coordinated control of the clutch and the engine in the gear shifting process is always a difficult point for controlling the AMT. The clutch non-separation AMT inherits the advantages of the traditional AMT, simultaneously cancels the control of the clutch, realizes the automatic gear shifting process by depending on the accurate regulation of the rotating speed and the torque of the engine and the control of the gear shifting mechanism of the transmission, and eliminates the defect of overlong clutch sliding time in the gear shifting process. The engine speed is usually controlled by an electromagnetic brake, or a hydraulic or electric brake, which consumes energy and generates heat.

Disclosure of Invention

in order to solve the defects in the prior art, the invention provides a model-based engine speed control method for AMT gear shifting, which comprises the following steps:

Firstly, an engine universal characteristic test and a transient characteristic test are carried out when the engine is in oil-cut deceleration or oil-increasing acceleration, wherein the universal characteristic test comprises the universal characteristic of an actuator;

Making a gas path average value model and an engine dynamics model based on the tests;

Analyzing and calibrating the optimal opening of the exhaust throttle valve to be closed based on the test data, and manufacturing an optimal opening MAP table of the exhaust throttle valve;

Establishing an observer by combining intake manifold pressure and air flow sensor values with an average value model;

Calculating the switch surface of the brake valve according to the Bang-Bang principle, and establishing an algebraic function to ensure that the time for the engine to reach the target rotating speed is shortest, and the rotating speed acceleration is in a given range when the engine is stable;

and calculating the fuel injection quantity for maintaining the engine to be stable at the target rotating speed when the exhaust throttle valve is fully opened, taking the fuel injection quantity as a feedforward value calculated by the fuel injection quantity, and adjusting the rotating speed through fuel injection feedback.

as a further improvement of the present invention, the calculation formula of the average value model is:

imep＝f₂(n,θ_exthrottle,T_im,P_im,P_ex,θ_EGR,θ_VGT,P_amb)

fmep＝f₃(imep,n,T_engine)

When the engine is cut off, the exhaust throttle valve quickly reaches the minimum value, the minimum value is obtained through calibration, and the exhaust throttle valve is quickly opened again after a period of time, and finally the aim is to calculate the maximum and minimum opening and closing surfaces, namely the closing duration of the throttle valve;

Wherein n is the engine speed, theta_exthrottleFor waste gas throttle opening, T_imIs the intake manifold temperature, P_imIs intake manifold pressure, P_exis the exhaust manifold pressure, θ_EGRIs EGR opening degree, θ_VGTIs the VGT opening degree, P_ambAt ambient pressure, T_engineWater temperature, V_sIs the engine displacement.

As a further improvement of the invention, the average value modeling is used to calculate the transient value, and the dynamic value of the cylinder intake and exhaust manifold pressure and the exhaust manifold pressure can be obtained, and the direct relationship between the valve action and the IMEP can be reflected by simplification, but the MAP and the sensor value are used as initial value input.

as a further improvement of the invention, a cost function is established to minimize the time for the engine to reach the target speed after the exhaust throttle valve is closed and opened, and the acceleration of the engine speed is less than a calibrated value when the target is reached.

As a further improvement of the invention, the observer is established by combining the values of the intake manifold pressure and the air flow sensor with an average value model, the time required by the engine speed to reach the target speed of the opening and closing surface is calculated by taking the pressure of the intake manifold and the exhaust manifold at the moment of fuel cut as an initial condition, the time required by the engine speed to reach the target speed after the throttle valve is fully opened is calculated, a cost function is established to ensure that the sum of the two periods of time is minimum, and meanwhile, when the target speed is reached, a constraint is imposed on the acceleration of the engine speed; thereafter, the accuracy is ensured by injection closed-loop control. .

From the above, the method for controlling the engine speed of the heavy-duty diesel vehicle provided by the invention has the following advantages compared with the prior art:

The control mode can calculate the maximum speed and the shortest time in real time on line, the adaptability is strong, the calibration quantity can be reduced based on the control of the model, the average value model reduces the burden for the control and has good transient response, the bang-bang control has the advantages of stability, and the precision can be ensured by roughly adjusting the waste gas throttle valve and finely adjusting the fuel injection quantity.

Drawings

Fig. 1 is a basic logic diagram of the Bang-Bang control employed by the present invention.

fig. 2 is a graph of exhaust brake valve opening degree versus braking time.

fig. 3 is a graph of VGT opening versus braking time.

FIG. 4 is a one-dimensional modeling model.

FIG. 5 is a diagram of FMEP calibration.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to specific embodiments and the accompanying drawings. In which like parts are designated by like reference numerals.

As shown in fig. 1 to 5, the method for controlling the engine speed of a heavy-duty diesel vehicle specifically comprises the following steps:

S100: receiving a gear shifting demand;

s200: judging whether the engine has a gear shifting and speed regulating condition;

S300: if the engine has the gear shifting condition, reducing the fuel injection quantity to enable the engine to achieve zero torque output;

S400: controlling the gear to be disengaged;

S500: the engine is decelerated by oil cut-off or accelerated by oil increment;

S600: and controlling the gear to be meshed and adjusting oil injection to the required torque, and adjusting the actuator to the normal working position.

The step S300 of reducing the fuel injection quantity to enable the engine to achieve zero torque output is to enable the transmission gear to be disengaged when the clutch is not disengaged, the step S500 of increasing or reducing the fuel is to enable the engine to achieve the rotating speed after gear shifting, and the step S600 of directly re-engaging the transmission gear due to the fact that the rotating speed is the same after the rotating speed is achieved.

The control method of the invention mainly improves the automatic speed changing system in S500 so as to achieve the purpose of accurately controlling the rotating speed.

for S500: if the engine is shifted and decelerated in the oil-cut deceleration or oil-increasing acceleration step, firstly, the opening and closing angle and the switch surface of a brake valve are controlled according to the Bang-Bang principle, and the specific steps of the oil-cut deceleration of the engine comprise:

S511: through all characteristic tests, particularly all characteristics of various valves (VGT, a waste gas bypass valve, an exhaust throttle valve, an intake throttle valve and the like) related to a gas circuit, a transient test of acceleration and fuel cut-off is designed, and the current water temperature, the rotating speed, an intake manifold pressure acquisition value, an intake temperature value, an intake air flow, an exhaust gas recirculation flow (if an exhaust gas recirculation system exists), an in-cylinder air-fuel ratio and the rotating speed of an engine are monitored.

S512, making an air passage average value model, reflecting the relation between the engine speed and various valves, VGT and engine states of an engine air passage, as shown in the following formula

imep＝f₂(n,θ_exthrottle,T_im,P_im,P_ex,θ_EGR,θ_VGT,P_amb)

fmep＝f₃(imep,n,T_engine)

Wherein n is the engine speed, theta_exthrottlefor waste gas throttle opening, T_imIs the intake manifold temperature, P_imis intake manifold pressure, P_exis the exhaust manifold pressure, θ_EGRIs EGR opening degree, θ_VGTIs the VGT opening degree, P_ambat ambient pressure, T_enginewater temperature, V_sIs the engine displacement.

IMEP is basically a function of the rotation speed, and the correction of the temperature and the pressure of an intake manifold and the ambient pressure is needed, and meanwhile, the correction of IMEP calculation by considering different VGT and EGR opening degrees is needed; FMEP is a function of IMEP and rotation speed, and the water temperature is required to be corrected;

When the engine is accelerated, the maximum value of the fuel injection quantity is controlled by the current air quantity and the allowable air-fuel ratio so as to prevent triggering smoke limit, and the control principle of the fuel injection quantity is the same as that of the engine when the engine is decelerated.

S513: calculating and finding out the optimal opening of the exhaust throttle valve, wherein the optimal opening is a MAP table with the difference value of the current engine speed and the target speed as input, and the output of the MAP table is the optimal opening of the exhaust throttle valve;

S514: establishing an observer by combining the values of the intake manifold pressure and the air flow sensor with an average value model, wherein the water temperature and the intake manifold temperature are sensor temperatures and are used for providing initial values for calculating the duration of the exhaust throttle valve under the optimal opening degree, namely taking the pressure of the intake manifold and the exhaust manifold at the oil-cut moment as an initial condition;

S515: the opening of the exhaust throttle valve is kept unchanged optimally, the time required by the engine speed to reach the opening and closing surface is calculated at the moment, the time required by the engine speed to reach a target value after the throttle valve is fully opened is calculated, a cost function is established to enable the sum of the two periods of time to be minimum, and meanwhile, when the target speed is reached, a constraint is provided for the engine speed acceleration, wherein the constraint is that the calibrated acceleration allowable deviation value is subtracted from the acceleration when the throttle valve is fully opened and the target speed is reached to be stable;

S516: calculating the fuel injection quantity for maintaining the engine to be stable at the target rotating speed when the exhaust throttle valve is fully opened, and taking the fuel injection quantity as a feedforward value for calculating the fuel injection quantity;

For S500: if the engine downshifts and accelerates in the oil-cut deceleration or oil-increasing acceleration step, the specific steps of the oil-increasing acceleration of the engine comprise:

S521: the steps are the same as S511 and S512, except that the exhaust throttle valve is always fully opened;

S522: the optimal fuel injection quantity of the engine for increasing the speed is found through the model calculation, the MAP table takes the difference value between the current engine rotating speed and the target rotating speed as input, and the output of the MAP table is the optimal fuel injection quantity. The maximum value of the fuel injection quantity is controlled by the current air quantity and the allowable air-fuel ratio so as to prevent triggering the smoke limit, and the control principle of the fuel injection quantity is the same as that of the fuel injection quantity when the engine is decelerated.

s523: the fuel injection quantity is kept unchanged, the time required by the rotating speed of the engine to reach the switch surface is calculated at the moment, the time required by the rotating speed of the engine to reach a target value is calculated after the fuel injection quantity is 0, a cost function is established to enable the sum of two periods of time to be minimum, and meanwhile, when the target rotating speed is reached, engine acceleration constraint is not generated unlike deceleration;

S524: calculating the stable fuel injection quantity of the engine under the target rotating speed, taking the stable fuel injection quantity as a feedforward value calculated by the fuel injection quantity, and feeding back the PID target of the part to be the target rotating speed of the engine;

And finally, after step S500, gear engagement is realized when the rotating speed of the engine reaches a target allowable range, then fuel injection is adjusted to the torque required by the driver, and the EGR and VGT are not influenced by the control strategy and are executed according to the original gas path strategy.