CN103244297A

CN103244297A - Constant-torque control system for lean-burn gasoline engine with NOx (oxides of nitrogen) adsorber-reduction catalytic converter

Info

Publication number: CN103244297A
Application number: CN2013101475342A
Authority: CN
Inventors: 李志军; 刘磊; 张洪洋; 侯普辉; 岳东鹏
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2013-04-25
Filing date: 2013-04-25
Publication date: 2013-08-14

Abstract

The invention relates to a control system for maintaining output speed and torque constant in a lean-burn working state and a rich-burn working state. The system comprises an ECU (electronic control unit) main controller 1, an engine speed monitoring module 2, an engine torque monitoring module 3, an original engine MAP storage unit 4 and an auxiliary MAP storage unit 5, and the engine speed monitoring module 2, the engine torque monitoring module 3, the original engine MAP storage unit 4 and the auxiliary MAP storage unit 5 are all connected with the ECU main controller 1. Compared with the prior art, the control system has the advantages that by adjustment of throttle percentage and angle of ignition advance, the torque and the speed are controlled within an acceptable range of a driver during switching between rich burn and lean burn; and treatment of NOx by an LNT (lean-NOx-trap) is guaranteed, and comfort of the driver or passengers is also guaranteed.

Description

The permanent torque control system of gasoline engine of being furnished with NOx absorbing and reducing catalytic converter

Technical field

The present invention relates to internal-combustion engine Rarefied combustion tail gas control technique, relate to a kind of gasoline engine periodicity alternate run of being furnished with NOx absorbing and reducing catalytic converter of realizing particularly and when lean-burn working state and dense combustion working state, keep output speed and the constant control system of moment of torsion.

Background technique

The petrol engine lean burn technology can improve the fuel economy of petrol engine effectively, and the discharging of reduction HC, CO, yet because the tail gas that motor is discharged is in the atmosphere of oxygen content surplus, make traditional triple effect catalytic converter TWC lose efficacy, can't under oxygen-enriched environment, efficiently remove NOx.This just needs to adopt the exhaust aftertreatment technology to reduce a large amount of NOx dischargings that produce under the lean burn conditions.NOx absorbing and reducing catalytic converter LNT(Lean-NOx-Trap) can reduce the discharging of gasoline engine NOx effectively.Gasoline engine is when adopting NOx absorbing and reducing catalyzed conversion preprocessor LNT work, its periodically alternation in lean-burn working state (NOx adsorptive process) and dense combustion working state (NOx reduction process) so that finish LNT in achieving lean combustion in engine state NOx adsorption and dense combustion state reducing NOx emissions thing process.If merely keep throttle opening constant, only keep certain mixer concentration by fuel injection amount, will inevitably make the external output torque of petrol engine produce bigger fluctuation, cause the bigger variation of engine speed, make the driveability deterioration of vehicle.Therefore need a kind of gasoline engine that can keep when dense rare conversion, to keep external output speed and the constant controlling method of moment of torsion substantially.

Summary of the invention

The objective of the invention is between air-fuel ratio, dense combustion or dense, lean-burn, in the step change procedure, guarantee the control system of petrol engine rotational speed and moment of torsion constant output.

The permanent torque control system of gasoline engine of being furnished with NOx absorbing and reducing catalytic converter, definition: the MAP figure of rotating speed, moment of torsion and throttle opening is that former machine MAP schemes during different air fuel ratio A/F; MAP figure with rotating speed, moment of torsion and throttle opening under different air fuel ratio A/F and the different ignition advance angle condition is auxiliary MAP figure; System comprises:

ECU master controller 1 is respectively at the continuous engine speed monitoring modular 2 of ECU master controller, Engine torque monitoring modular 3, former machine MAP figure storage unit 4, auxiliary MAP figure storage unit 5.

In the periodic step change procedure of engine air-fuel ratio, engine speed monitoring module monitors engine speed changes, and the output of Engine torque monitoring module monitors moment of torsion changes; The MAP figure that the ECU master controller at first calls in the former machine MAP figure storage unit regulates throttle opening, until the fluctuation absolute value of the rotating speed particular value Q less than certain setting, and the torque ripple absolute value is during less than the particular value P of certain setting, and this process is the coarse adjustment process;

Identical before if above-mentioned adjusting can not realize moment of torsion output and switch, the ECU master controller calls the MAP figure operation in the auxiliary MAP figure storage unit, and the moment of torsion output after switching between rare until making, dense combustion or dense, the lean-burn is before identical with switching; This process is the thin tuning process.

If auxiliary rotating speed and the torque curve point of intersection of MAP figure under different ignition advance angles and throttle opening condition exists a plurality of and former machine MAP figure rotating speed and the identical situation in moment of torsion point of intersection, then the MAP of the ignition advance angle that employing and point of intersection same number are maximum schemes.

As preferred version: described Q=50rpm; Described P=5N.m.

The present invention is with respect to the advantage of prior art: by regulating throttle opening and ignition advance angle, realized dense, when the phase process is switched, moment of torsion and rotating speed control are in driver's acceptable scope; Both guarantee the processing of the NOx of LNT, also guaranteed driver or motroist's travelling comfort.

Description of drawings

Fig. 1 is system schematic of the present invention.1 represents the ECU master controller, and 2 represent the engine speed monitoring modular, and 3 represent the Engine torque monitoring modular, the former machine MAP figure storage unit of 4 representatives, and the auxiliary MAP figure storage unit of 5 representatives, 6 represent motor.

Fig. 2 be the automatically controlled gasoline engine of CA3GA2 transformed among the embodiment 1 air fuel ratio A/F be under 12 o'clock each throttle openings moment of torsion with the change in rotational speed curve.

Fig. 3 be the automatically controlled gasoline engine of CA3GA2 transformed among the embodiment 1 air fuel ratio A/F be under 20 o'clock each throttle openings moment of torsion with the change in rotational speed curve.

Embodiment

Embodiment 1:

Must demarcate concrete motor.This research selects the CA3GA2 electric control gasoline engine to demarcate, rotating speed, moment of torsion and throttle opening when carrying out different air fuel ratio A/F compare experiment, thereby obtain the former machine MAP figure of motor dense rare when conversion rotating speed, moment of torsion and throttle opening during different air fuel ratio A/F, be stored in the former machine MAP figure storage unit 4.

At the timing signal of assisting MAP figure, because the throttle opening of this moment also is an object to be calibrated by main controller controls, therefore its variable as MAP figure can not be treated.So the MAP figure of this moment is to be the three-dimensional MAP figure that variable is drawn with rotating speed and accelerator pedal position.During calibration experiment, rotating speed, moment of torsion and throttle opening when adopting different air fuel ratio A/F and ignition advance angle compare, in order to obtain auxiliary MAP figure, are stored in the auxiliary MAP figure storage unit 5.

When air fuel ratio changed, the ECU master controller called MAP figure operation in the former machine MAP figure storage unit until monitoring the output of engine speed and moment of torsion when being in the prespecified range, satisfies Q＜50rpm and P＜5N.m simultaneously that is:; The ECU master controller begin to call MAP figure in the auxiliary MAP figure storage unit be adjusted to after switching between rare, dense combustion or dense, the lean-burn moment of torsion output with switch before identical.

Contrast Fig. 2 and Fig. 3, same rotating speed and torque point different throttle opening of correspondence on these two figure, the variable quantity of throttle opening when obtaining this point thus and be air fuel ratio A/F and changing between 12 and 20, the MAP figure that ignition advance angle changes when utilizing the method for interpolation can obtain air fuel ratio A/F to change between 12 and 20 is as auxiliary MAP figure.Be example with rotation speed n=1800r/min, when air fuel ratio A/F be 12, when throttle opening is 0.5%, its corresponding output torque is about 45N.m; When air fuel ratio A/F was 20, constant in order to guarantee output torque, according to Fig. 2 as can be known, throttle opening should be adjusted into 2.5%.

In like manner, the MAP figure that ignition advance angle changes in the time of also can obtaining A/F than conversion between 12 and 20 is as auxiliary MAP figure.

With this original MAP figure value storage former machine MAP figure during as dense combustion (air fuel ratio A/F=12), lean-burn (air fuel ratio A/F=20) in the ROM of ECU.All the other are dense, the auxiliary MAP figure when lean-burn periodicity step changes makes one by one and is stored in according to the method in the auxiliary MAP figure storage unit, choose automatically at switching instant and call.

Claims

1. the permanent torque control system of gasoline engine of being furnished with NOx absorbing and reducing catalytic converter, definition: the MAP figure of rotating speed, moment of torsion and throttle opening is that former machine MAP schemes during different air fuel ratio A/F; MAP figure with rotating speed, moment of torsion and throttle opening under different air fuel ratio A/F and the different ignition advance angle condition is auxiliary MAP figure; It is characterized in that, comprising:

ECU master controller (1) is respectively at the continuous engine speed monitoring modular (2) of ECU master controller, Engine torque monitoring modular (3), former machine MAP figure storage unit (4), auxiliary MAP figure storage unit (5).