Fuel property determination from accumulated intake air amount and accumulated fuel supply amount

• US 6,314,944 B1
• Filed: 07/19/2000
• Issued: 11/13/2001
• Est. Priority Date: 07/30/1999
• Status: Expired due to Term

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Majima, Yoshihiro
• Primary Examiner(s): SOLIS, ERICK R
• Application Number:
  US09/619,495
• Time in Patent Office: 482 Days
• Field of Search: 123/49, 123/1.A, 73/350.2, 731/173
• US Class Current: 123/491
• CPC Class Codes: F02D 19/061 by controlling fuel injectors
• CPC Class Codes: F02D 19/0636 by estimation, i.e. without using direct measurements of a corresponding sensor
• CPC Class Codes: F02D 19/0649 Liquid fuels having different boiling temperatures, volatilities, densities, viscosities, cetane or octane numbers
• CPC Class Codes: F02D 2041/1418 Several control loops, either as alternatives or simultaneous
• CPC Class Codes: F02D 2200/0611 Fuel type, fuel composition or fuel quality
• CPC Class Codes: F02D 2200/0612 determined by estimation
• CPC Class Codes: F02D 41/0025 Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
• CPC Class Codes: F02D 41/047 Taking into account fuel evaporation or wall wetting; special correction after fuel cut-off F02D41/126
• CPC Class Codes: F02D 41/187 using a hot wire flow sensor
• CPC Class Codes: G01N 33/2829 mixtures of fuels, e.g. determining the RON-number
• CPC Class Codes: Y02T 10/30 Use of alternative fuels, e.g. biofuels

Abstract

In a fuel supply control for engines, the amount of fuel supplied to the engine is corrected based on property of fuel which is determined immediately after engine starting. The fuel property is determined based on the amount of fuel injected, but remaining upstream the cylinder and not burned in a cylinder. This fuel property value TNEN is estimated from an accumulated intake air amount TAF and an accumulated fuel injection amount TTAU as TNEN=TTAU·14.7−TTAF. In the above equation, 14.7 indicates the stoichiometric air-fuel ratio to which the air-fuel ratio of air-fuel mixture is controlled while the accumulated intake air amount and the accumulated fuel injection amount are measured. If the calculated value indicates that the fuel is a heavy type, the amount of fuel injected in the next engine starting operation is increased to compensate for the amount of fuel which will remain upstream the cylinder. Alternatively, the fuel property may be determined based on an increase of pressure in a fuel tank detected while the fuel tank is in a fully closed condition.

Claims

1. An apparatus for determining property of fuel supplied to an engine comprising:

an air-fuel ratio-sensor for detecting an air-fuel ratio of air-fuel mixture supplied to an engine;

accumulated intake air amount calculation means for calculating an accumulated amount of air supplied to the engine for a predetermined period from a time of starting the engine to a time of an output of the air-fuel ratio sensor indicative of reaching a target air-fuel ratio;

accumulated fuel amount calculation means for calculating an accumulated amount of fuel supplied to the engine for the predetermined period; and

fuel property determination means for determining fuel property based on a fuel property value which is a predetermined function of the calculated accumulated intake air amount and the calculated accumulated fuel amount.

2. The apparatus as in claim 1, wherein:

the time of the output of the air-fuel ratio sensor is after an activation of the air-fuel ratio sensor; and

the fuel property determination means calculates the fuel property value from a difference between the calculated accumulated intake air amount and a product of the calculated accumulated fuel amount and the target air-fuel ratio, and determines the fuel property from the calculated fuel property value.

3. The apparatus as in claim 1, wherein:

the fuel property determination means corrects the calculated fuel property value with a parameter variable with a coolant temperature of the engine.

4. The apparatus as in claim 1, further comprising:

fast catalyst heating means for retarding an ignition timing for starting the engine under a cold temperature condition thereby to heat an exhaust purifying catalyst quickly,

wherein the fast catalyst heating means includes means for reducing an amount of retardation of the ignition timing for starting the engine under the cold temperature condition next time, when the fuel property determination means determines that the fuel is a heavy type.

5. The apparatus as in claim 1, further comprising:

fuel correction means for correcting, based on a fuel property determination that the fuel is a heavy type, the amount of fuel to be supplied to the engine in a next starting of the engine.

6. The apparatus as in claim 5, wherein:

the fuel correction means gradually decreases an amount of correcting the amount of fuel as an elapse of time after starting the engine.

7. The apparatus as in claim 5, wherein:

the fuel correction means corrects an amount of correcting the amount of fuel based on a rotation speed and an intake condition of the engine.

8. The apparatus as in claim 5, wherein:

the fuel correction means stops correcting the amount of fuel, when an accumulated amount of correcting the fuel amount from starting the engine reaches a predetermined value determined based on the calculated fuel property value.

9. The apparatus as in claim 1, further comprising:

refill determination means for retarding an ignition timing of the engine after starting the engine, and determining a refill of fuel of different property based on a decrease in a rotation speed of the engine resulting from a retardation of the ignition timing.

10. The apparatus as in claim 9, further comprising:

fuel increasing means for increasing the amount of fuel to be supplied to the engine in response to a determination of refill of a heavy type fuel.

11. The apparatus as in claim 1, further comprising:

open-loop control means for calculating the amount of fuel irrespective of the output of the air-fuel ratio sensor until the air-fuel ratio senor is activated, so that the air-fuel ratio of the air-fuel mixture supplied to the engine is controlled around the target air-fuel ratio; and

closed-loop control means for calculating the amount of fuel supplied to the engine in response to the output of the air-fuel ratio sensor after the air-fuel ratio sensor is activated, so that the air-fuel ratio of the air-fuel ratio mixture supplied to the engine is feedback-controlled to the target air-fuel ratio.

12. A method of controlling an engine having a cylinder comprising:

starting an engine;

measuring an amount of intake air supplied to the engine;

injecting fuel to the engine in an amount calculated in correspondence with the measured intake air amount;

estimating an amount of fuel injected to the engine but remaining upstream the cylinder;

determining fuel property based on the estimated amount of fuel remaining upstream the cylinder;

storing the determined fuel property after the engine is stopped; and

correcting the amount of injected fuel based on the stored fuel property when the engine is started again after stopped once.

13. The method as in claim 12, wherein the estimating includes:

accumulating the measured amount of intake air and the amount of injected fuel, respectively, for a predetermined period from a time of starting the engine to a time of an output of an air-fuel ratio sensor indicative of reaching a target air-fuel ratio; and

determining a relationship between the accumulated amount of intake air and the accumulated amount of injected fuel, so that the amount of fuel remaining upstream the cylinder is estimated from the determined relationship.

14. The method as in claim 13, wherein:

the relationship is determined as a difference between the accumulated amount of measured intake air and a product of the accumulated amount of injected fuel and the target air-fuel ratio.

15. The method as in claim 14, wherein:

the difference is corrected with a parameter variable with a coolant temperature of the engine.

16. The method as in claim 12, wherein:

the amount of fuel to be injected to the engine in a next starting of the engine is increased when the stored fuel property is indicative of a heavy-type of fuel.

17. The method as in claim 16, wherein:

an amount of increase in the fuel injected in the next starting of the engine is gradually decreased as an elapse of time after starting the engine.

18. The method as in claim 12, further comprising:

retarding an ignition timing of the engine after starting the engine;

determining a refill of fuel of different property based on a decrease in a rotation speed of the engine resulting from a retardation of the ignition timing; and

increasing the amount of injected fuel in response to a determination of refill of a heavy type fuel.