Method for controlling a dual-supercharged combustion engine
AssigneeIfp Energies Nouvelles
InventorsLeroy THOMAS, Alexandre CHASSE, Jonathan CHAUVIN
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Abstract
The invention relates to a combustion engine equipped with a dual supercharging system in which a mechanical compressor is driven by an electric motor. The method controls a combustion engine with the electric motor being controlled by determining a rotational speed setpoint for positive-displacement compressor using a supercharge volume filling model.
Claims14
1) A method for controlling a combustion engine (1) equipped with a supercharging system, said supercharging system comprising a turbocharger (2) and a positive-displacement compressor (3) for compressing a gas mixture at the intake of said combustion engine (1) and a by-pass circuit arranged parallel to said positive-displacement compressor, comprising a controllable by-pass valve (4), said positive-displacement compressor (3) being driven by an electric motor (11), characterized in that the following stages are carried out:
- a) acquiring a boost pressure setpoint Psuralsp;
- b) constructing a filling model for the supercharge volume contained between the intake valves of said engine (1) on the one hand and positive-displacement compressor (3) and by-pass valve (4) on the other;
- c) converting said boost pressure setpoint Psuralsp to a rotational speed setpoint Ncprsp for said positive-displacement compressor (3) using said supercharge volume filling model, and
- d) controlling said electric motor (11) according to said rotational speed setpoint Ncprsp of said positive-displacement compressor (3).
5) A method as claimed in any one of the previous claims, wherein said filling model is determined by means of a filling equation of said supercharge volume defined by a flow rate conservation formula of the type:
- P
- .
- sural
- =
- RT
- sural
- V
- sural
-
- (
- D
- cpr
- -
- D
- bp
- -
- D
- asp
- )
- with {dot over (P)}sural the derivative of said boost pressure Psural with respect to time, R the ideal gas constant, Vsural the supercharge volume, Dcpr the flow coming from said positive-displacement compressor (3), Dbp the flow leaving through said by-pass valve (4) that is a function of the opening of said by-pass valve and Dasp the flow sucked into the cylinders of said engine (1).
9) A method as claimed in any one of the previous claims, wherein said by-pass valve (4) is closed when said electric motor is controlled.
10) A method as claimed in any one of the previous claims, wherein said by-pass valve (4) is closed when the pressure difference between said boost pressure setpoint Psuralsp and the pressure upstream from said positive-displacement compressor Pavcpr is greater than a threshold, said by-pass valve (4) being open otherwise.
11) A combustion engine equipped with a supercharging system, said supercharging system comprising a turbocharger (2) and a positive-displacement compressor (3) for compressing a gas mixture at the intake of said combustion engine (1) and a by-pass circuit arranged parallel to said positive-displacement compressor, comprising a controllable by-pass valve (4), said positive-displacement compressor (3) being driven by an electric motor (11), characterized in that it also comprises means for implementing the method as described in any one of the previous claims.
Dependencies are inferred from the claim text.