Fuel injection control apparatus with injector response delay compensation

• US 5,605,136 A
• Filed: 12/14/1995
• Issued: 02/25/1997
• Est. Priority Date: 01/18/1995
• Status: Expired due to Fees

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Inventors: Nakashima, Kazushi
• Primary Examiner(s): Dolinar, Andrew M.
• Application Number:
  US08/572,640
• Time in Patent Office: 439 Days
• Field of Search: 123/478, 123/480, 123/486, 123/488, 123/494
• US Class Current: 123/480
• CPC Class Codes: F02D 2200/0602 Fuel pressure
• CPC Class Codes: F02D 2200/503 Battery correction, i.e. corrections as a function of the state of the battery, its output or its type
• CPC Class Codes: F02D 2200/703 Atmospheric pressure
• CPC Class Codes: F02D 2250/31 Control of the fuel pressure
• CPC Class Codes: F02D 41/3005 Details not otherwise provided for
• CPC Class Codes: F02D 41/32 of the low pressure type F02D41/3082 takes precedence

Abstract

A fuel injection control apparatus has a pressure regulator with a fuel return pipe installed within a fuel tank. The pressure regulator regulates pressure of fuel supplied to a fuel injector to be constant relative to an atmospheric pressure or an in-tank pressure. An electronic control unit drives the fuel injector by adding an invalid injection time to a required injection time determined based on engine operating conditions. The invalid injection time, which compensates for the response delays of the fuel injector, is determined by a battery voltage and a pressure difference between the fuel pressure and a selected pressure which is lower than the atmospheric pressure. The selected pressure may be a minimum pressure which an intake pressure of the engine becomes during fuel injection operation.

Claims

1. A fuel injection control apparatus comprising:

a fuel injector mounted on an engine to inject fuel into said engine when driven by a battery;

a pressure regulator operatively connected to said fuel injector to regulate a pressure of said fuel constant relative to a predetermined pressure which is independent of an intake pressure of said engine;

means for determining a required fuel injection time of said fuel injector based on operating conditions of said engine;

means for determining an invalid injection time of said fuel injector based on a voltage of said battery and a pressure difference between said pressure of said fuel and a selected pressure which is lower than an atmospheric pressure;

means for compensating said required fuel injection time by adding said invalid injection time to determine a final injection time; and

means for driving said fuel injector by said battery during said final injection time,

wherein said selected pressure is a minimum pressure which said intake pressure becomes during operation of said engine.

2. A fuel injection control apparatus according to claim 1, wherein said invalid injection time determining means has a memory storing therein said invalid injection time relative to said voltage of said battery.

3. A fuel injection control apparatus according to claim 1, wherein said predetermined pressure is one of an atmospheric pressure and a pressure within a fuel tank.

4. A fuel injection control apparatus comprising:

a fuel injector mounted on an engine to inject fuel into said engine when driven by a battery;

a pressure regulator operatively connected to said fuel injector to regulate a pressure of said fuel constant relative to a predetermined pressure which is independent of an intake pressure of said engine;

means for determining a required fuel injection time of said fuel injector based on operating conditions of said engine;

means for determining an invalid injection time of said fuel injector based on a voltage of said battery and a pressure difference between said pressure of said fuel and a selected pressure which is lower than an atmospheric pressure;

means for compensating said required fuel injection time by adding said invalid injection time to determine a final injection time; and

means for driving said fuel injector by said battery during said final injection time,

wherein said selected pressure is a minimum pressure which said intake pressure becomes during fuel injection of said fuel injector.

5. A fuel injection control apparatus according to claim 4, wherein said predetermined pressure is one of an atmospheric pressure and a pressure within a fuel tank.

6. A fuel injection control apparatus comprising:

a fuel injector mounted on an engine to inject fuel into said engine when driven by a battery;

a pressure regulator operatively connected to said fuel injector to regulate a pressure of said fuel constant relative to a predetermined pressure which is independent of an intake pressure of said engine;

means for determining a required fuel injection time of said fuel injector based on operating conditions of said engine;

means for determining an invalid injection time of said fuel injector based on a voltage of said battery and a pressure difference between said pressure of said fuel and a selected pressure which is lower than an atmospheric pressure;

means for compensating said required fuel injection time by adding said invalid injection time to determine a final injection time; and

means for driving said fuel injector by said battery during said final injection time,

wherein said selected pressure is a minimum pressure which said intake pressure becomes during fuel injection by said fuel injector in an idling operation of said engine.

7. A fuel injection control apparatus according to claim 6, wherein said predetermined pressure is one of an atmospheric pressure and a pressure within a fuel tank.

8. A fuel injection control apparatus comprising:

a fuel injector mounted on an engine to inject fuel into said engine when driven by a battery;

a pressure regulator operatively connected to said fuel injector to regulate a pressure of said fuel constant relative to a predetermined pressure which is independent of an intake pressure of said engine;

means for determining a required fuel injection time of said fuel injector based on operating conditions of said engine;

means for determining an invalid injection time of said fuel injector based on a voltage of said battery and a pressure difference between said pressure of said fuel and a selected pressure which is lower than an atmospheric pressure;

means for compensating said required fuel injection time by adding said invalid injection time to determine a final injection time; and

means for driving said fuel injector by said battery during said final injection time,

wherein said selected pressure is determined to prevent an air-fuel ratio of an air-fuel mixture to said engine from deviating to a fuel-lean side relative to a stoichiometric air-fuel ratio even when said intake pressure changes.

9. A fuel injection control apparatus according to claim 8, wherein said predetermined pressure is one of an atmospheric pressure and a pressure within a fuel tank.

10. A fuel injection control apparatus comprising:

a fuel injector mounted on an engine to inject fuel into said engine when driven by a battery;

a pressure regulator operatively connected to said fuel injector to regulate a pressure of said fuel constant relative to a predetermined pressure which is independent of an intake pressure of said engine;

means for determining a required fuel injection time of said fuel injector based on operating conditions of said engine;

means for determining an invalid injection time of said fuel injector based on a voltage of said battery and a pressure difference between said pressure of said fuel and a selected pressure which is lower than an atmospheric pressure;

means for compensating said required fuel injection time by adding said invalid injection time to determine a final injection time; and

means for driving said fuel injector by said battery during said final injection time,

wherein said selected pressure is determined to prevent an air-fuel ratio of air-fuel mixture to said engine from deviating to a fuel-lean side relative to a stoichiometric air-fuel ratio in at least an idling condition of said engine.

11. A fuel injection control apparatus according to claim 10, wherein said predetermined pressure is one of an atmospheric pressure and a pressure within a fuel tank.

12. A fuel injection control apparatus comprising:

a fuel injector mounted on an engine to inject fuel into said engine when driven by a battery;

a pressure regulator operatively connected to said fuel injector to regulate a pressure of said fuel so that it is unchanged by an intake pressure of said engine; and

an electronic control unit programmed to perform the processes of,

determining a required fuel injection time of said fuel injector based on operating conditions of said engine,

determining an invalid injection time of said fuel injector based on a voltage of said battery and a pressure difference between said pressure of said fuel and a selected pressure which is produced when a throttle valve of said engine is in a closed condition,

compensating said required fuel injection time by adding said invalid injection time to determine a final injection time, and

driving said fuel injector by said battery during said final injection time,

wherein said invalid injector time has a value effective to avoid a fuel-lean condition of an air-fuel mixture relative to a stoichiometric air-fuel ratio.