Idle speed control system
First Claim
1. A method for controlling engine idle speed of a motor vehicle having a fuel vapor recovery system coupled to the engine air intake through a control valve, comprising the steps of:
- initiating idle speed control during each period when engine operating parameters are in a predetermined state;
calculating a desired engine speed upon said initiation of said idle speed control period;
generating an initial throttle position for a bypass throttling device based upon said desired engine speed;
correcting said initial throttle position upon said initiation of said idle speed control period by a correction factor calculated during a previous idle speed control period;
updating said correction factor during current idle speed control operation for application during a subsequent idle speed control period by learning average difference between said desired engine speed and actual engine speed; and
inhibiting said learning during actuation of the fuel vapor recovery valve.
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Accused Products
Abstract
An idle speed control system includes a bypass throttling device coupled in parallel with the primary engine throttle. At the beginning of each idle speed control period, a controller generates an initial bypass throttle position from a desired or reference engine speed. Correction of this initial position is provided based upon a learned error between initial bypass throttle position and the actual position which is maintained by feedback control. The learning routine is enabled in response to an indication that the quantity of inducted fuel vapors is below a minimum value.
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Citations
11 Claims
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1. A method for controlling engine idle speed of a motor vehicle having a fuel vapor recovery system coupled to the engine air intake through a control valve, comprising the steps of:
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initiating idle speed control during each period when engine operating parameters are in a predetermined state; calculating a desired engine speed upon said initiation of said idle speed control period; generating an initial throttle position for a bypass throttling device based upon said desired engine speed; correcting said initial throttle position upon said initiation of said idle speed control period by a correction factor calculated during a previous idle speed control period; updating said correction factor during current idle speed control operation for application during a subsequent idle speed control period by learning average difference between said desired engine speed and actual engine speed; and inhibiting said learning during actuation of the fuel vapor recovery valve. - View Dependent Claims (2, 3)
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4. A method for controlling engine idle speed of a motor vehicle having a fuel vapor recovery system coupled to the engine air intake through a control valve, comprising the steps of:
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initiating idle speed control during each period when engine operating parameters remain in a predetermined state; calculating a desired engine speed upon said initiation of said idle speed control period; generating an initial throttle position for a throttling device bypassing a primary engine throttle valve, said initial bypass throttle position being based upon said desired engine speed; correcting said initial bypass throttle position upon said initiation of said idle speed control period by a correction factor calculated by comparing said desired engine speed to actual engine speed during a previous idle speed control period; and learning a new correction factor during current idle speed control operation for application during a subsequent idle speed control period, said learning being enabled in response to an indication that quantity of recovered fuel vapors inducted into the engine is less than a preselected value. - View Dependent Claims (5, 6)
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7. An idle speed control system for a motor vehicle having a fuel vapor recovery system coupled to an engine air intake through a control valve, comprising:
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an idle speed controller for controlling a bypass throttle coupled to the engine air intake in response to a feedback variable and an initial throttle position signal and an initial throttle position correction signal; feedback means for generating said feedback variable by integrating a difference between said desired engine speed and said actual engine speed; positioning means for converting said desired engine speed into said initial throttle position signal; and learning means for generating said initial throttle position correction signal by integrating said feedback variable and concurrently driving said feedback variable towards zero to learn an average difference between said initial throttle position and actual throttle position maintained by said idle speed controller, said learning means being enabled when an indication is provided that quantity of recovered fuel vapors inducted into the engine is less than a preselected value. - View Dependent Claims (8, 9, 10, 11)
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Specification