Method for controlling fuel supply to internal combustion engines having catalytic means for purifying exhaust gases, at operation in a high speed region

• US 4,542,728 A
• Filed: 06/08/1983
• Issued: 09/24/1985
• Est. Priority Date: 06/15/1982
• Status: Expired due to Term

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Otobe, Yutaka, Kishi, Noriyuki
• Primary Examiner(s): Cox, Ronald B.
• Application Number:
  US06/502,105
• Time in Patent Office: 839 Days
• Field of Search: 123/492, 123/440, 123/489, 60/277
• US Class Current: 123/687
• CPC Class Codes: F02B 1/04 with fuel-air mixture admission into cylinder
• CPC Class Codes: F02D 41/1483 Proportional component

Abstract

A fuel supply control method for controlling the quantity of fuel being supplied to an internal combustion engine having a catalytic means for purifying detrimental ingredients in exhaust gases, in a feedback manner responsive to the output of a means for detecting the concentration of an ingredient in the exhaust gases. When the engine is operating in a predetermined high speed operating region wherein the rotational speed of the engine is higher than a predetermined speed, the above feedback control is interrupted and the fuel quantity is increased by a predetermined amount so as to make the air/fuel ratio of a mixture being supplied to the engine richer than a theoretical mixture ratio. Preferably, the above predetermined speed is set at a value which is a maximum value of rpm above which the catalyst bed temperature of the exhaust gas purifying means will exceed a predetermined maximum allowable value, if the air/fuel ratio is controlled to the theoretical mixture ratio or a value close thereto. Further, preferably, the above predetermined fuel amount by which the fuel quantity is increased in the above predetermined high speed operating region is set to larger values as the intake pipe absolute pressure increases.

Claims

1. A method for controlling the quantity of fuel being supplied to an internal combustion engine having an intake passage and a catalytic means for purifying detrimental ingredients in exhaust gases emitted from the engine, in a feedback manner responsive to an output from a means for detecting the concentration of an ingredient in the exhaust gases so that the air/fuel ratio of an air/fuel mixture being supplied to the engine is controlled to a theoretical mixture ratio, said catalytic means being of the type being apt to most increase in bed temperature when the air/fuel ratio of the air/fuel mixture assumes said theoretical mixture ratio or a value close thereto, the method comprising the steps of:

determining whether or not the engine is operating in a predetermined high speed operating region wherein the rotational speed of the engine is higher than a predetermined value which is a maximum value of the rotational speed of the engine above which the bed temperature of said catalytic means will exceed a predetermined maximum allowable value, if the air/fuel ratio of the air/fuel mixture being supplied to the engine is controlled to said theoretical mixture ratio or a value close thereto, and the absolute pressure in said intake passage is higher than a predetermined value; and

(2) interrupting said feedback control and increasing the quantity of fuel being supplied to the engine by a predetermined amount, so that the resultant air/fuel mixture being supplied to the engine has an air/fuel ratio richer than said theoretical mixture ratio, when it is determined in said step (1) that the engine is operating in said predetermined high speed operating region, said predetermined amount being set to larger values as the absolute pressure in said intake passage increases.

2. A method as claimed in claim 1, wherein said predetermined value of the rotational speed of the engine in said step (1) is set to different values between when the operating condition of the engine enters said predetermined high speed operating region and when it leaves same.

3. A method as claimed in claim 1 wherein said predetermined value of the absolute pressure in said intake passage in said step (1) is set to different values between when the operating condition of the engine enters said predetermined high speed operating region and when it leaves same.