CN104295387B - A kind of matter adjustable type engine start control method based on command torque - Google Patents

Abstract

The invention discloses a kind of matter adjustable type engine start control method based on command torque, be difficult to engine startup fuel injection amount and accurately control and the problem that affects engine startability solving prior art. Obtain the starting drag torque under electromotor difference speed of crankshaft and coolant temperature by experiment; Starting according to electromotor controls requirement, it is determined that the target angular acceleration function of starting process, and calculates acceleration resistance square, it is achieved the control to engine speed in starting process and starting time; The deviation of the change calculations electromotor actual angular acceleration according to electromotor actual crank rotating speed, electromotor actual angular acceleration and target angular acceleration determines compensation torque; Start drag torque, acceleration resistance square and compensation torque and be added the command torque obtaining starting demand; According to indicated efficiency, demand command torque is converted to fuel injection amount. This method can ensure the optimum. fuel injection amount realized under various starting conditions needed for starting process.

Description

A kind of matter adjustable type engine start control method based on command torque

Technical field

The present invention relates to the control of a kind of combustion engine, be specifically related to the control strategy of starting process fuel injection manner based on the controllable matter adjustable type electromotor of demand command torque and starting time

Background technology

For the control of fuel injection manner in the starting process of matter adjustable type electromotor, it is by relatively entering the air capacity of cylinder supply optimum. fuel injection amount, it is made to form gaseous mixture in cylinder and burn, promotion piston does work, overcome engine interior resistance, drive crank rotation, make engine speed reach the set goal value.

In normal starting and starting process, the change of engine speed is directly related with the fuel injection amount of setting and spray regime thereof. The fuel injection amount of usual starting process is determined by engine pedestal rating test. Owing to starting process control strategy is different, start emitted dose and spray regime has very big difference. If fuel injection amount is too small, spray regime is unreasonable, cannot complete normal starting process; Otherwise fuel injection amount too much not only Fuel Consumption increase, is unfavorable for energy-conservation, and causes the discharge capacitys such as hydrocarbon, carbon monoxide and microgranule to increase. Therefore, actual conditions according to state of starting operating, set rational fuel injection amount and adopt rational spray regime, it is possible not only to effectively control the starting time, and can also effectively control hydrocarbon, carbon monoxide and the Particulate Emission of starting process, to adapt to constantly strict vehicular engine energy-saving and emission-reduction requirement.

Start ambient condition condition is more complicated, due to coolant temperature, injection advance angle, expulsion pressure, fuel injection manner difference, indicated efficiency of engine difference is relatively big, and the fuel injection amount needed for completing starting process is also different. Traditional method for starting-controlling, in order to ensure reliable starting, only compensates certain fuel injection amount simply generally according to starting state, it is difficult to realizes the accurate control of starting process fuel injection amount, therefore directly affects the startability of electromotor.Along with the development of the low carbonization of automobile, for improving the starting performance of vehicular engine, a kind of perfect starting control strategy is necessary.

Summary of the invention

The present invention solves the problem being difficult to accurately controlling of engine startup fuel injection amount and affecting engine startability that prior art exists, it is provided that the control method of a kind of starting fuel emitted dose based on demand command torque and indicated efficiency.

For solving above-mentioned technical problem, the present invention adopts the following technical scheme that realization:

A kind of matter adjustable type engine start control method based on command torque, it is characterised in that comprise the steps:

Step one, by experiment acquisition electromotor difference speed of crankshaft n_crankAnd coolant temperature T_wUnder starting drag torque Trq_d; Speed of crankshaft n during according to engine start_crankWith coolant temperature T_wDetermine starting drag torque Trq_d;

Step 2, control requirement according to the starting of electromotor, it is determined that the target angular acceleration function �� of starting process₀T (), based on the target angular acceleration �� of starting process₀, calculate acceleration resistance square Trq_I, it is achieved the control to engine speed in starting process and starting time.

Step 3, according to electromotor actual crank rotating speed n_crankChange calculations electromotor actual angular acceleration ��, by electromotor actual angular acceleration �� and target angular acceleration ��₀Deviation determine compensation torque Trq_c; Actual angular acceleration �� and target angular acceleration ��₀Deviation be just, compensate torque reduce, deviation be negative, then compensation torque increase.

Step 4, general start drag torque Trq_d, acceleration resistance square Trq_IWith compensation torque Trq_cIt is added the command torque Trq obtaining starting demand_i, i.e. Trq_i=Trq_d+Trq_I+Trq_c;

Step 5, according to indicated efficiency by demand command torque Trq_iBeing converted to fuel injection amount q, fuel injection amount q is by basic fuel emitted dose q₀Form with fuel injection correction amount �� q two parts:

Further technical scheme is as follows:

The detailed process of step 2 is:

A. the expection starting time t set according to the requirement of starting time₀, set starting according to starting motor and engine characteristics and start to spray rotating speed n₁, starting process complete rotating speed n₂; Obtain the rotary inertia I of target engine.

B. requirement is controlled according to the starting of electromotor, it is determined that target angular acceleration function ��₀(t), ��₀T () meets at expection starting time t₀Interior integration is that starting process completes rotating speed n₂Start to spray rotating speed n with starting₁Difference, namely ${\∫}_0^{t_0}{\mathrm{\β}}_0\left(t\right)\mathrm{dt}=n_2-n_1;$

C. formula Trq is utilized_I=I ��₀Calculate acceleration resistance square Trq_I, wherein: ��₀For target angular acceleration, I is engine moment inertia.

The detailed process of step 5 is:

A. the indicated efficiency �� of electromotor when according to standard cold starting_i0Calculating demand command torque Trq_iRequired basic fuel emitted dose q₀,Wherein �� is pi, and �� is number of stroke, and i is number of cylinders, H_uFor lower calorific value of fuel;

B. when starting conditions changes, the change according to indicated efficiency, revise fuel injection amount �� q, namelyK is indicated efficiency modifying factor, obtains by experiment.

C. by basic fuel emitted dose q₀It is added with fuel injection correction amount �� q and obtains starting fuel emitted dose q, q=q₀+��q��

Compared with prior art, there is advantages that starting process follows strictly the expection angular acceleration that calculates of starting time and carries out, and with compensation tache, ensure the best command torque realized under various environmental condition needed for starting process, ensureing the target starting time, starting process reliability is high simultaneously; By setting the different expection starting times, thus changing the actual starting time of electromotor; The fuel injection amount of starting process is changed by demand command torque and is obtained, and only need to adjust indicated efficiency modifying factor when changing fuel injection parameters or burning condition changes, it is ensured that realize the optimum. fuel injection amount needed for starting process under various starting conditions; Adopt the algorithm of different target angular acceleration, it is possible to adjust starting process curve, it is achieved play seamlessly transitting of trend idling and other operating modes.

Accompanying drawing explanation

Below in conjunction with accompanying drawing, the present invention is further illustrated:

Fig. 1 is the basic controlling flow process figure of patent of the present invention

Fig. 2 is the design sketch of the embodiment one of patent of the present invention

Fig. 3 is the design sketch of the embodiment two of patent of the present invention

Detailed description of the invention

In order to introduce present disclosure in detail, relevant concept more defined below:

Definition one: command torque, refers to the crankshaft output torque that the indicated work equivalence that one cycle of operation heat to power output of cylinder obtains becomes.At start-up period, required command torque is used to overcome in engine startup the moment of resistance and inertia resistance square, uses Trq_iRepresent.

Definition two: start drag torque, refer to that electromotor stops oil when certain stable coolant temperature, utilize motor run electromotor to make it maintain the torque that a certain starting speed provides, use Trq_dRepresent.

Definition three: acceleration resistance square (or inertia resistance square), refers to when in starting process, engine speed raises, and is used for the torque overcome required for engine moment inertia. Acceleration resistance square is that engine moment inertia is with crankshaft angular acceleration long-pending, uses Trq_IRepresent.

Below in conjunction with specific embodiment, the present invention is explained in detail:

Embodiment one:

Matter adjustable type engine start based on command torque of the present invention controls to comprise the following steps:

Step 1, obtains engine start drag torque Trq by experiment_dWith speed of crankshaft n_crankAnd coolant temperature T_wRelation, and Binding experiment obtain starting drag torque Trq_dWith speed of crankshaft n_crankAnd coolant temperature T_wRelation, according to the current speed of crankshaft n of electromotor_crankWith coolant temperature T_wDetermine starting drag torque Trq_d. Specifically, in the present embodiment, at coolant temperature T_wUnder, stop fuel injection, and electric dynamometer is converted to motor towing astern electromotor to give speed of crankshaft n_crank, and keep coolant temperature T_wConstant, the required torque provided of electric dynamometer is starting drag torque Trq_d; Adjust coolant temperature T_wWith speed of crankshaft n_crankFor other values, obtain the starting drag torque Trq of correspondence_d, thus setting up starting drag torque Trq_dWith speed of crankshaft n_crankAnd coolant temperature T_wRelation.

Step 2: control requirement according to the starting of electromotor, it is determined that the target angular acceleration function �� of starting process₀T (), based on the target angular acceleration �� of starting process₀, calculate acceleration resistance square Trq_I. Including three below concrete steps:

A: set expection starting time t according to the requirement of starting time₀, set starting according to starting motor and engine characteristics and start to spray rotating speed n₁, starting process complete rotating speed n₂; Obtain the rotary inertia I of target engine. Start and start rotating speed n₁It is by starting the rotating speed of fuel injection driven by motor electromotor arrives; Proceed-to-send rotating speed n₂It it is the rotating speed of the electromotor disengaging starting state set. In the present embodiment, t₀=3s, n₁=250r/min; n₂=750r/min, I=0.5kg m²��

B: control requirement according to the starting of electromotor, it is determined that target angular acceleration function ��₀(t), target angular acceleration ��₀Meet it at expection starting time t₀Interior integration is that starting process completes rotating speed n₂Start to spray rotating speed n with starting₁Difference, namelyIn the present embodiment, n₂=750r/min, n₁=250r/min, I=0.5kg m², adopt the method that in starting process, target angle adds quick depletion,�� is pi, and t is current relative to the relative instant initially entering start-up period. Target angular acceleration ��₀Reduce along with the increase of relative instant t, as relative instant t=t₀Time, target angular acceleration ��₀It is zero.

C: based target angular acceleration ��₀With engine moment inertia I, utilize formula Trq_I=I ��₀Calculate acceleration resistance square Trq_I. In the present embodiment, Trq_I=5.8 (3-t).

Step 3: according to electromotor actual crank rotating speed n_crankCalculate electromotor actual angular acceleration ��, according to electromotor actual angular acceleration �� and target angular acceleration ��₀Deviation determine compensation torque Trq_c.Actual angular acceleration �� is by speed of crankshaft n_crankObtain after differential calculation, namely�� is pi, and t is current relative to the relative instant initially entering start-up period. If the target angular acceleration �� that actual angular acceleration �� calculates more than step 4₀, then torque Trq is compensated_cReduce, if the target angular acceleration �� that actual border angular acceleration �� calculates less than step 4₀, then torque Trq is compensated_cIncrease. In the present embodiment, compensate torqueI is engine moment inertia, F_cFor penalty coefficient, t is current relative to the relative instant initially entering start-up period, t₀For set the expection starting time, for 3s, I=0.5kg m², F_c=1, so havingPenalty coefficient F_cCan according to real engine adjustment.

Step 4: obtain the command torque Trq of starting demand_i. The command torque of demand is for starting drag torque Trq_d, acceleration resistance square Trq_I, compensate torque Trq_cThree's sum, i.e. Trq_i=Trq_d+Trq_I+Trq_c;

Step 5: according to indicated efficiency by demand command torque Trq_iBeing converted to fuel injection amount q, fuel injection amount q is by basic fuel emitted dose q₀Form with fuel injection correction amount �� q two parts. Including in detail below three steps:

A: the indicated efficiency �� of (GB/T18297-2001 " automobile engine method for testing performance ") electromotor when according to standard cold starting_i0Calculating demand command torque Trq_iRequired basic fuel emitted dose q₀,Wherein �� is pi, and �� is number of stroke, and i is number of cylinders, H_uFor lower calorific value of fuel. In the present embodiment, number of stroke ��=4, number of cylinders i=4.

B: when starting conditions changes, the change calculations fuel injection correction amount �� q according to indicated efficiency.Wherein k_��For indicated efficiency modifying factor, obtain by experiment.

C: the basic fuel emitted dose q that will calculate₀It is added with fuel injection correction amount �� q and obtains starting fuel emitted dose q=q₀+��q��

Embodiment two:

Matter adjustable type engine start based on command torque of the present invention controls to comprise the following steps:

Step 1, obtains engine start drag torque Trq by experiment_dWith speed of crankshaft n_crankAnd coolant temperature T_wRelation, and Binding experiment obtain starting drag torque Trq_dWith speed of crankshaft n_crankAnd coolant temperature T_wRelation, according to the current speed of crankshaft n of electromotor_crankWith coolant temperature T_wDetermine starting drag torque Trq_d. Specifically, in the present embodiment, at coolant temperature T_wUnder, stop fuel injection, and electric dynamometer is converted to motor towing astern electromotor to give speed of crankshaft n_crank, and keep coolant temperature T_wConstant, the required torque provided of electric dynamometer is starting drag torque Trq_d; Adjust coolant temperature T_wWith speed of crankshaft n_crankFor other values, obtain the starting drag torque Trq of correspondence_d, thus setting up starting drag torque Trq_dWith speed of crankshaft n_crankAnd coolant temperature T_wRelation.

Step 2: control requirement according to the starting of electromotor, it is determined that the target angular acceleration function �� of starting process₀T (), based on the target angular acceleration �� of starting process₀, calculate acceleration resistance square Trq_I. Including three below concrete steps:

A: set expection starting time t according to the requirement of starting time₀, set starting according to starting motor and engine characteristics and start to spray rotating speed n₁, starting process complete rotating speed n₂; Obtain the rotary inertia I of target engine. Start and start rotating speed n₁It is by starting the rotating speed of fuel injection driven by motor electromotor arrives; Proceed-to-send rotating speed n₂It it is the rotating speed of the electromotor disengaging starting state set.In the present embodiment, t₀=3s, n₁=250r/min; n₂=750r/min, I=0.5kg m²��

B: control requirement according to the starting of electromotor, it is determined that target angular acceleration function ��₀(t). Target angular acceleration function ��₀T () meets it at expection starting time t₀Interior integration is that starting process completes rotating speed n₂Start to spray rotating speed n with starting₁Difference, namelyIn the present embodiment, n₂=750r/min, n₁=250r/min, I=0.5kg m², t₀=2s, adopts the method that in starting process, target angular acceleration is constant, namely�� is pi, and t is current relative to the relative instant initially entering start-up period.

C: utilize formula Trq_I=I ��₀Calculate acceleration resistance square Trq_I, wherein: ��₀For target angular acceleration, I is engine moment inertia. In the present embodiment: Trq_I=13.09 (kg m).

Step 3: according to electromotor actual crank rotating speed n_crankCalculate electromotor actual angular acceleration ��, according to electromotor actual angular acceleration �� and target angular acceleration ��₀Deviation determine compensation torque Trq_c. Actual angular acceleration �� is by speed of crankshaft n_crankObtain after differential calculation, namely�� is pi. In the present embodiment, compensate torqueI is engine moment inertia, for 0.5kg m², F_cFor penalty coefficient, it is current relative to the relative instant initially entering start-up period, t for taking 1, t₀For the expection starting time set, for 2s, so havingPenalty coefficient F_cCan according to real engine adjustment.

Step 4: obtain the command torque Trq of starting demand_i. The command torque of demand is for starting drag torque Trq_d, acceleration resistance square Trq_I, compensate torque Trq_cThree's sum, i.e. Trq_i=Trq_d+Trq_I+Trq_c;

Step 5: according to indicated efficiency by demand command torque Trq_iBeing converted to fuel injection amount q, fuel injection amount q is by basic fuel emitted dose q₀Form with fuel injection correction amount �� q two parts. Including in detail below three steps:

A: the indicated efficiency �� of (GB/T18297-2001 " automobile engine method for testing performance ") electromotor when according to standard cold starting_i0Calculating demand command torque Trq_iRequired basic fuel emitted dose q₀,Wherein �� is pi, and �� is number of stroke, and i is number of cylinders, H_uFor lower calorific value of fuel. In the present embodiment, number of stroke ��=4, number of cylinders i=4.

B: when starting conditions changes, calculates fuel injection correction amount �� q.k_��For indicated efficiency modifying factor, obtain by experiment.

C: the basic fuel emitted dose q that will calculate₀It is added with fuel injection correction amount �� q and obtains starting fuel emitted dose q=q₀+��q��

Embodiment one and embodiment two have employed different expection starting times and different target angular acceleration function ��₀T (), it is different that the target angle of starting process accelerates rule, and the Changing Pattern of acceleration resistance square also differs, and the velocity variations of starting process also differs, and starting effect is respectively as shown in Figures 2 and 3.

Claims (3)

1. the matter adjustable type engine start control method based on command torque, it is characterised in that comprise the steps:

Step one, by experiment acquisition electromotor difference speed of crankshaft n_crankAnd coolant temperature T_wUnder starting drag torque Trq_d; Speed of crankshaft n during according to engine start_crankWith coolant temperature T_wDetermine starting drag torque Trq_d;

Step 2, control requirement according to the starting of electromotor, it is determined that the target angular acceleration function �� of starting process₀T (), based on the target angular acceleration �� of starting process₀, calculate acceleration resistance square Trq_I, it is achieved the control to engine speed in starting process and starting time;

Step 3, according to electromotor actual crank rotating speed n_crankChange calculations electromotor actual angular acceleration ��, by electromotor actual angular acceleration �� and target angular acceleration ��₀Deviation determine compensation torque Trq_c; Actual angular acceleration �� and target angular acceleration ��₀Deviation be just, compensate torque reduce, deviation be negative, then compensation torque increase;

Step 4, general start drag torque Trq_d, acceleration resistance square Trq_IWith compensation torque Trq_cIt is added the command torque Trq obtaining starting demand_i, i.e. Trq_i=Trq_d+Trq_I+Trq_c;

Step 5, according to indicated efficiency by demand command torque Trq_iBeing converted to fuel injection amount q, fuel injection amount q is by basic fuel emitted dose q₀Form with fuel injection correction amount �� q two parts.

2. a kind of matter adjustable type engine start control method based on command torque described in claim 1, it is characterised in that the detailed process of step 2 is as follows:

A. the expection starting time t set according to the requirement of starting time₀, set starting according to starting motor and engine characteristics and start to spray rotating speed n₁, starting process complete rotating speed n₂; Obtain the rotary inertia I of target engine;

B. requirement is controlled according to the starting of electromotor, it is determined that target angular acceleration function ��₀(t), ��₀T () meets at expection starting time t₀Interior integration is that starting process completes rotating speed n₂Start to spray rotating speed n with starting₁Difference, namely

C. formula Trq is utilized_I=I ��₀Calculate acceleration resistance square Trq_I, wherein: ��₀For target angular acceleration, I is engine moment inertia.

3. a kind of matter adjustable type engine start control method based on command torque described in claim 1, it is characterised in that the detailed process of step 5 is as follows:

A. the indicated efficiency �� of electromotor when according to standard cold starting_i0Calculating demand command torque Trq_iRequired basic fuel emitted dose q₀,Wherein �� is pi, and �� is number of stroke, and i is number of cylinders, H_uFor lower calorific value of fuel;

B. when starting conditions changes, the change according to indicated efficiency, revise fuel injection amount �� q, namelyK is indicated efficiency modifying factor, obtains by experiment;

C. by basic fuel emitted dose q₀It is added with fuel injection correction amount �� q and obtains starting fuel emitted dose q, q=q₀+��q��