Apparatus for controlling internal combustion engine equipped with evaporative emission control system

• US 6,227,177 B1
• Filed: 06/24/1999
• Issued: 05/08/2001
• Est. Priority Date: 07/07/1998
• Status: Expired due to Fees

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Kouda, Yasuo, Yamafuji, Takahiro
• Primary Examiner(s): Moulis, Thomas N.
• Application Number:
  US09/339,122
• Time in Patent Office: 684 Days
• Field of Search: 123/698, 123/520, 123/704, 123/516, 123/518, 123/519, 123/399
• US Class Current: 123/520
• CPC Class Codes: F02D 41/0042 Controlling the combustible mixture as a function of the canister purging, e.g. control of injected fuel to compensate for deviation of air fuel ratio when purging

Abstract

In an apparatus for controlling an internal combustion engine equipped with an evaporative emission control system comprises an electronic control unit configured to be connected to at least an electronically-controlled throttle and an electronic fuel injection system, the control unit comprises a desired air flow rate setting section setting a desired air flow rate on the basis of at least an opening of an accelerator, and a desired fuel-flow quantity setting section setting a desired quantity of fuel flow on the basis of the desired air flow rate and a predetermined air/fuel ratio. A purge gas flow detection section is provided for detecting a purge-air flow rate of purge air flowing through the purge line and a purge fuel-flow quantity of purge fuel vapor flowing through the purge line. A desired throttle air flow rate is arithmetically calculated by subtracting the purge-air flow rate from the desired air flow rate, whereas a desired fuel-injection quantity is arithmetically calculated by subtracting the purge fuel-flow quantity from the desired quantity of fuel flow. The opening of the electronically-controlled throttle is controlled on the basis of the desired throttle air flow rate, whereas the fuel-injection quantity of fuel to be injected from the fuel injector is controlled on the basis of the desired fuel-injection quantity.

Claims

1. An apparatus for controlling an internal combustion engine equipped with an evaporative emission control system having at least a canister temporarily adsorbing fuel vapor emitted from a fuel tank, a purge line through which the fuel vapor adsorbed by the canister flows to an induction system, and a purge control valve disposed in the purge line, said apparatus comprising:

a control unit configured to be connected to at least an electronically-controlled throttle and an electronic fuel injection system having a fuel injector provided for each engine cylinder;

said control unit comprising;

a desired air flow rate setting section setting a desired air flow rate on the basis of at least an opening of an accelerator;

a desired fuel-flow quantity setting section setting a desired quantity of fuel flow on the basis of at least the opening of the accelerator;

a purge-air flow rate detection section detecting a purge-air flow rate of purge air flowing through the purge line via the purge control valve to the induction system;

a purge fuel-flow quantity detection section detecting a purge fuel-flow quantity of purge fuel vapor flowing through the purge line via the purge control valve to the induction system;

a desired throttle air flow rate arithmetic-calculation section arithmetically calculating a corrected air flow rate by subtracting the purge-air flow rate from the desired air flow rate;

a throttle control section controlling an opening of the electronically-controlled throttle on the basis of the corrected air flow rate;

a desired fuel-injection quantity arithmetic-calculation section arithmetically calculating a corrected fuel-Injection quantity by subtracting the purge fuel-flow quantity from the desired quantity of fuel flow; and

a fuel-injection control section controlling a fuel-injection quantity of fuel to be injected from the fuel injector on the basis of the corrected fuel-injection quantity.

2. The apparatus as claimed in claim 1, wherein said desired fuel-flow quantity setting section arithmetically calculates the desired fuel-flow quantity on the basis of both a predetermined air/fuel ratio and the desired air flow rate.

3. The apparatus as claimed in claim 1, wherein said purge-air flow rate detection section detects both an opening of the purge control valve and a negative pressure in the induction system, and arithmetically calculates the purge-air flow rate on the basis of the opening of the purge control valve and the negative pressure in the induction system.

4. The apparatus as claimed in claim 1, wherein said purge fuel-flow quantity detection section comprises a hydrocarbon sensor attached to the purge line downstream of the purge control valve to detect a concentration of hydrocarbon contained within purge gas consisting of the purge air and the purge fuel vapor, and arithmetically calculates the purge fuel-flow quantity on the basis of both the purge-air flow rate and the concentration of hydrocarbon.

5. In an internal combustion engine equipped with an evaporative emission control system having at least a canister temporarily adsorbing fuel vapor emitted from a fuel tank, a purge line through which the fuel vapor adsorbed by the canister flows to an induction system, and a purge control valve disposed in the purge line, an integrated engine control apparatus for electronically controlling an air/fuel ratio, comprising:

an electronically-controlled throttle whose opening is changeable arbitrarily in response to an opening of an accelerator;

an electronic fuel injection system having a fuel injector provided for each engine cylinder;

control means configured to be connected to at least said electronically-controlled throttle, said electronic fuel injection system, and the purge control valve, for controlling the air/fuel ratio;

said control means comprising;

a desired air flow rate setting means for setting a desired air flow rate on the basis of at least the opening of the accelerator;

a desired fuel-flow quantity setting means for setting a desired quantity of fuel flow on the basis of at least the opening of the accelerator;

a purge-air flow rate estimation means for estimating a purge-air flow rate of purge air flowing through the purge line via the purge control valve to the induction system on the basis of both an opening of the purge control valve and a negative pressure in the induction system;

a purge fuel-flow quantity estimation means for estimating a purge fuel-flow quantity of purge fuel vapor flowing through the purge line via the purge control valve to the induction system on the basis of both the purge air flow rate estimated by the purge-air flow rate estimation means and a concentration of hydrocarbon contained within purge gas consisting of the purge air and the purge fuel vapor flowing through the purge line;

a desired throttle air flow rate arithmetic-calculation means for arithmetically calculating a corrected air flow rate by subtracting the purge-air flow rate from the desired air flow rate;

a throttle control means for controlling an opening of the electronically-controlled throttle on the basis of the corrected air flow rate;

a desired fuel-injection quantity arithmetic-calculation means for arithmetically calculating a corrected fuel-injection quantity by subtracting the purge fuel-flow quantity from the desired quantity of fuel flow; and

a fuel-injection control means for controlling a fuel-injection quantity of fuel to be injected from the fuel injector on the basis of the corrected fuel-injection quantity.

6. A method for controlling an air/fuel ratio of an internal combustion engine, wherein the internal combustion engine includes an electronically-controlled throttle whose opening is changeable arbitrarily in response to an opening of an accelerator, an electronic fuel injection system having a fuel injector provided for each engine cylinder, and an evaporative emission control system having at least a canister temporarily adsorbing fuel vapor emitted from a fuel tank, a purge line through which the fuel vapor adsorbed by the canister flows to an induction system, and a purge control valve disposed in the purge line, the method comprising:

setting a desired air flow rate on the basis of at least the opening of the accelerator,

setting a desired quantity of fuel flow on the basis of at least the opening of the accelerator,

estimating a purge-air flow rate of purge air flowing through the purge line via the purge control valve to the induction system on the basis of both an opening of the purge control valve and a negative pressure in the induction system,

estimating a purge fuel-flow quantity of purge fuel vapor flowing through the purge line via the purge control valve to the induction system on the basis of both the purge air flow rate estimated and a concentration of hydrocarbon contained within purge gas consisting of the purge air and the purge fuel vapor flowing through the purge line,

arithmetically calculating a corrected air flow rate by subtracting the purge-air flow rate from the desired air flow rate,

controlling an opening of the electronically-controlled throttle on the basis of the corrected air flow rate,

arithmetically calculating a corrected fuel-injection quantity by subtracting the purge fuel-flow quantity from the desired quantity of fuel flow, and

controlling a fuel-injection quantity of fuel to be injected from the fuel injector on the basis of the corrected fuel-injection quantity.

7. A method for controlling an air/fuel ratio of an internal combustion engine, wherein the internal combustion engine includes an electronically-controlled throttle whose opening is changeable arbitrarily in response to an opening of an accelerator, an electronic fuel injection system having a fuel injector provided for each engine cylinder, and an evaporative emission control system having at least a canister temporarily adsorbing fuel vapor emitted from a fuel tank, a purge line through which the fuel vapor adsorbed by the canister flows to an induction system, and a purge control valve disposed in the purge line, the method comprising:

detecting engine speed, the opening of the accelerator, an opening of the purge control valve, a negative pressure in the induction system, and a concentration of hydrocarbon contained within purge gas consisting of purge air and purge fuel vapor flowing through the purge line,

setting a desired air flow rate on the basis of the engine speed and the opening of the accelerator,

setting a desired quantity of fuel flow on the basis of the desired air flow rate and a predetermined air/fuel ratio,

estimating a purge-air flow rate of purge air flowing through the purge line via the purge control valve to the induction system on the basis of both the opening of the purge control valve and the negative pressure in the induction system,

estimating a purge fuel-flow quantity of purge fuel vapor flowing through the purge line via the purge control valve to the induction system on the basis of both the purge air flow rate estimated and a concentration of hydrocarbon contained within purge gas consisting of the purge air and the purge fuel vapor flowing through the purge line,

arithmetically calculating a corrected air flow rate by subtracting the purge-air flow rate from the desired air flow rate,

controlling an opening of the electronically-controlled throttle on the basis of the corrected air flow rate,

arithmetically calculating a corrected fuel-injection quantity by subtracting the purge fuel-flow quantity from the desired quantity of fuel flow, and

controlling a fuel-injection quantity of fuel to be injected from the fuel injector on the basis of the corrected fuel-injection quantity.