US 5,469,832 A · Canister purge control method and apparatus for internal combustion engine

Abstract

According to one embodiment of the invention, a purge quantity is controlled in proportion to an air quantity sucked into an internal combustion engine. During normal operation of the engine, a purge air-fuel ratio is calculated according to a purge rate and an air-fuel feedback control quantity. During transient operation of the engine, a target air-fuel ratio feedback control quantity is calculated according to the purge rate and the purge air-fuel ratio. When the difference between the air-fuel ratio feedback control quantity and the target air-fuel ratio feedback control quantity is greater than a predetermined value, the air-fuel ratio feedback control quantity is corrected to the target air-fuel ratio feedback control quantity. An undue fluctuation in air-fuel ratio of a fuel mixture supplied to cylinders occurring upon rapid fluctuation in purge rate can be suppressed.

Claims15

Dependent claims

An engine air/fuel mixture control method comprising:

temporarily recovering a fuel vapor generated in a fuel tank to fuel vapor recovering means,
purging said recovered fuel vapor to said engine during operation of said engine with a purge air quantity (Qevp) being controlled at purge ratio (Kevp) proportional to an air quantity (Qtvo) supplied to said engine, and
feedback controlling an air-fuel ratio in the engine intake by a feedback control quantity (.alpha.);
said method comprising the steps of:
determining a purge air-fuel ratio (AFevp), in response to a first purge ratio (Kevp1) and a feedback control quantity (.alpha.) of said air-fuel ratio;
and
determining a target air-fuel ratio feedback control quantity according to said estimated purge air-fuel ratio (AFevp) and a second ratio (Kevp2);
and
changing said feedback control quantity (.alpha.) of said air-fuel ratio according to said calculated target air-fuel ratio feedback control quantity when Kevp1 and Kevp2 are unequal.

6 more elements

A canister purge control apparatus for an internal combustion engine, including fuel vapor recovering means for temporarily recovering a fuel vapor generated in a fuel tank, means for purging said recovered fuel vapor to said engine during operation of said engine with a purge air quantity being controlled at a purge rate proportional to an air quantity supplied to said engine, and means for feedback controlling an air-fuel ratio;

said apparatus comprising:
means for estimating a purge air-fuel ratio according to said purge rate and a feedback control quantity of said air-fuel ratio;
and
means for calculating a target air-fuel ratio feedback control quantity according to said purge air-fuel ratio estimated and said purge rate in a transient operational condition of said engine, and correcting said feedback control quantity of said air-fuel ratio according to said target air-fuel ratio feedback control quantity calculated.

1 more element

Dependencies are inferred from the claim text.

Canister purge control method and apparatus for internal combustion engine

Life of this patent

Canister purge control method and apparatus for internal combustion engine

Life of this patent

Abstract

Claims15