Control System for Internal Combustion Engine

• US 20070225892A1
• Filed: 04/21/2005
• Published: 09/27/2007
• Est. Priority Date: 04/28/2004
• Status: Active Grant

• Current Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Original Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Inventors: Sato, Masahiro, Yasui, Yuji, Saito, Mitsunobu, Higashitani, Kosuke, Tagami, Hiroshi
• Granted Patent: US 7,451,754 B2
• Time in Patent Office: Days
• US Class Current: 701/104
• CPC Class Codes: F01L 13/0063 by modification of cam contact point by displacing an intermediate lever or wedge-shaped intermediate element, e.g. Tourtelot
• CPC Class Codes: F01L 2800/00 Methods of operation using a variable valve timing mechanism
• CPC Class Codes: F01L 2820/032 Electric motors
• CPC Class Codes: F02B 75/048 by means of a variable crank stroke length
• CPC Class Codes: F02D 13/023 the change of valve timing is caused by the change in valve lift, i.e. both valve lift and timing are functionally related
• CPC Class Codes: F02D 13/0238 by shifting the phase, i.e. the opening periods of the valves are constant
• CPC Class Codes: F02D 15/02 by alteration or displacement of piston stroke
• CPC Class Codes: F02D 2200/0402 the parameter being determined by using a model of the engine intake or its components
• CPC Class Codes: F02D 2400/08 Redundant elements, e.g. two sensors for measuring the same parameter
• CPC Class Codes: F02D 41/182 for the control of a fuel injection device
• CPC Class Codes: F02D 41/22 Safety or indicating devices for abnormal conditions in air/fuel ratio feedback systems F02D41/1495, in electric control linkage F02D11/107, in purge control systems F02M25/0809
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

A control system for an internal combustion engine, which is capable of enhancing the accuracy of fuel control and ignition timing control even when there is a possibility that the reliability of a calculated intake air amount lowers, and enables reduction of manufacturing costs. An ECU of the control system calculates a first estimated intake air amount according to a valve lift, a cam phase, and a compression ratio, calculates a second estimated intake air amount according to the flow rate of air detected by an air flow sensor. The ECU determines a fuel injection amount according to the first estimated intake air amount when an estimated flow rate Gin_vt calculated based on an engine speed, the valve lift, the cam phase, and the compression ratio is within the range of Gin_vt≦Gin1, and according to the second estimated intake air amount when Gin2≦Gin_vt.

Claims

1. A control system for an internal combustion engine in which a variable intake mechanism changes an amount of intake air drawn into cylinders thereof as desired, the control system controlling an amount of fuel to be supplied to a combustion chamber, comprising:

operating condition parameter-detecting means for detecting an operating condition parameter indicative of an operating condition of the variable intake mechanism;

first estimated intake air amount-calculating means for calculating a first estimated intake air amount as an estimated value of the amount of intake air according to the operating condition parameter;

air flow rate-detecting means for detecting a flow rate of air flowing through an intake passage of the engine;

second estimated intake air amount-calculating means for calculating a second estimated intake air amount as an estimated value of the amount of intake air according to the flow rate of air;

load parameter-detecting means for detecting a load parameter indicative of load on the engine; and

fuel amount-determining means for determining the amount of fuel according to the first estimated intake air amount when the load parameter is within a first predetermined range, and determining the amount of fuel according to the second estimated intake air amount when the load parameter is within a second predetermined range different from the first predetermined range.

2. A control system as claimed in claim 1, wherein the first predetermined range and the second predetermined range are set such that they do not overlap each other, and

wherein said fuel amount-determining means determines the amount of fuel according to the first estimated intake air amount and the second estimated intake air amount when the load parameter is between the first predetermined range and the second predetermined range.

3. A control system as claimed in claim 1, further comprising first failure-determining means for determining whether or not said air flow rate-detecting means is faulty, and

wherein said fuel amount-determining means calculates the amount of fuel according to the first estimated intake air amount irrespective of a value of the load parameter, when said first failure-determining means determines that said air flow rate-detecting means is faulty.

4. A control system as claimed in claim 1, further comprising:

second failure-determining means for determining whether or not the variable intake mechanism is faulty; and

drive means for driving the variable intake mechanism such that the amount of intake air becomes equal to a predetermined value, when said second failure-determining means determines that the variable intake mechanism is faulty, and

wherein said fuel amount-determining means determines the amount of fuel according to the predetermined value, when said second failure-determining means determines that the variable intake mechanism is faulty.

5. A control system as claimed in any one of claims 1 to 4, wherein the variable intake mechanism comprises at least one of a variable cam phase mechanism for changing a phase of an intake camshaft of the engine with respect to a crankshaft of the engine, a variable valve lift mechanism for changing a lift of each intake valve of the engine, and a variable compression ratio mechanism for changing a compression ratio of the engine.

6. A control system for an internal combustion engine, comprising:

intake air amount-calculating means for calculating an amount of intake air drawn into cylinders of the engine;

engine speed-detecting means for detecting a rotational speed of the engine;

maximum intake air amount-calculating means for calculating a maximum amount of intake air which can be drawn into each cylinder at the rotational speed of the engine, according to the rotational speed of the engine; and

ignition timing-determining means for determining ignition timing of the engine according to a ratio of the intake air amount to the maximum intake air amount or a ratio of the maximum intake air amount to the intake air amount, and the rotational speed of the engine.

7. A control system as claimed in claim 6, wherein the engine includes a variable intake mechanism for changing the amount of intake air as desired,

the control system further comprising:

operating condition parameter-detecting means for detecting an operating condition parameter indicative of an operating condition of the variable intake mechanism;

air flow rate-detecting means for detecting a flow rate of air flowing through an intake passage of the engine; and

load parameter-detecting means for detecting a load parameter indicative of load on the engine, and

wherein said intake air amount-calculating means calculates the amount of intake air according to the operating condition parameter when the load parameter is within a first predetermined range, and calculates the amount of intake air according to the flow rate of air when the load parameter is within a second predetermined range different from the first predetermined range.

8. A control system as claimed in claim 7, wherein the first predetermined range and the second predetermined range are set such that they do not overlap each other, and

wherein said intake air amount-calculating means calculates the amount of intake air according to the operating condition parameter and the flow rate of air when the load parameter is between the first predetermined range and the second predetermined range.

9. A control system as claimed in claim 7, further comprising first failure-determining means for determining whether or not said air flow rate-detecting means is faulty, and

wherein said intake air amount-calculating means calculates the amount of intake air according to the operating condition parameter irrespective of a value of the load parameter, when said first failure-determining means determines that said air flow rate-detecting means is faulty.

10. A control system as claimed in claim 7, further comprising:

second failure-determining means for determining whether or not the variable intake mechanism is faulty;

drive means for driving the variable intake mechanism such that the amount of intake air becomes equal to a predetermined value, when said second failure-determining means determines that the variable intake mechanism is faulty; and

failure-time target engine speed-setting means for setting a failure-time target engine speed as a target of the rotational speed of the engine, when said second failure-determining means determines that the variable intake mechanism is faulty, and

wherein said ignition timing-determining means determines the ignition timing with a predetermined feedback control algorithm such that the rotational speed of the engine becomes equal to the failure-time target engine speed, when said second failure-determining means determines that the variable intake mechanism is faulty.

11. A control system as claimed in any one of claims 7 to 10, wherein the variable intake mechanism comprises at least one of a variable cam phase mechanism for changing a phase of an intake camshaft of the engine with respect to a crankshaft of the engine, a variable valve lift mechanism for changing a lift of each intake valve of the engine, and a variable compression ratio mechanism for changing a compression ratio of the engine.