Engine Idle Speed Control for Low-Temperature Vibration Reduction
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Solution Overview
Problem
Internal combustion engine idle speed vibrations increase in low-temperature environments due to resonant frequency changes in the driving power transmission system, leading to potential resonance and inefficiency.
Innovation Solution
A controller adjusts the idle speed of the internal combustion engine based on unused time, setting it to a higher speed if the vehicle is kept in a low-temperature environment for an extended period, and gradually returning to normal idle speed as the temperature stabilizes, while also considering driving conditions and load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the idle speed is set to a standard value to maintain fuel efficiency, then fuel consumption is reduced, but vibration increases when the vehicle is kept in a low-temperature environment for an extended period due to resonant frequency changes
Solution Approach 1:
The idle speed is made dynamically adjustable based on the duration of vehicle inactivity in low-temperature environments. The ECU monitors unused time and automatically adjusts idle speed between a standard value (for fuel efficiency) and a high value (for vibration reduction), allowing the system to adapt to changing conditions without manual intervention
Solution Approach 2:
The idle speed parameter is changed based on the unused time threshold. When the vehicle remains inactive in low-temperature conditions beyond a certain threshold, the idle speed parameter is adjusted from the standard value to a higher value to avoid resonance, and subsequently returned to the standard value after a reference period, thereby optimizing both fuel efficiency and vibration control
2Object-affected harmful factors
If the idle speed is increased to avoid resonant frequency and reduce vibration, then vibration is reduced, but fuel consumption increases
Solution Approach 1:
The high idle speed is applied periodically only during the specific condition of extended vehicle inactivity in low-temperature environments, rather than continuously. After a reference period following the unused time threshold, the idle speed returns to the standard value, minimizing fuel consumption while still addressing vibration issues when necessary
3Object-affected harmful factors
If the idle speed is continuously adjusted to adapt to changing resonant frequency, then vibration control is improved, but system complexity increases
Solution Approach 1:
The system uses its own existing sensors and control capabilities to monitor unused time and automatically adjust idle speed without requiring external intervention or additional complex control mechanisms. The ECU leverages its existing processing power to implement the vibration control logic
Solution Approach 2:
The control system manages complexity by changing only one key parameter (idle speed) based on a single threshold condition (unused time), rather than adjusting multiple parameters simultaneously. This simplifies the control logic while still achieving effective vibration control
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces vibrations and maintains fuel efficiency by preventing resonance and adjusting idle speed in response to changing environmental and operational conditions.
Implementation Method 1
the resonant speed of driving power transmission system changes if the vehicle is kept in a low-temperature environment (for example, lower than −15° C.) with the engine stopped
Data Source
AI summary
An ECU for controlling an engine counts an unused time TIM of engine in a low-temperature environment. If the unused time TIM is shorter than a predetermined reference value, the ECU sets idle speed immediately after start of operation of the engine to a first idle speed, and if the unused time TIM is longer than the reference value, sets the idle speed to a second idle speed higher than the first idle speed. If duration of the second idle speed exceeds a reference period determined by state of driving of the vehicle, the ECU sets the idle speed to be lower than the second idle speed. In this manner, increased vibration in idling operation in a low-temperature environment can be prevented.