Valve Timing Control Unit Wear Reduction via Phase Swing
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Solution Overview
Problem
Valve timing control units in internal combustion engines face wear issues in gears and bearings due to continuous pressure application, leading to impaired smooth operation and reduced longevity.
Innovation Solution
A valve timing control unit that includes a driving rotary body, a driven rotary body, an electric motor, a deceleration gear, and a phase sensor unit, with a controller that performs phase difference convergence and swing control to distribute pressure evenly across the bearing, reducing wear by adjusting the target phase and fluctuation amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric actuator continuously applies pressure to maintain a predetermined valve timing, then the valve timing control is stable, but the gears and bearings experience wear at specific positions
Solution Approach 1:
The patent implements periodic reciprocating motion of the control shaft through the electric actuator. When the actual phase fluctuation is within a predetermined range and the target phase has been maintained for a predetermined period, the actuator reverses its rotation direction periodically, causing the control shaft to reciprocate. This periodic action distributes the pressure application over different gear contact positions and bearing locations, preventing concentrated wear at specific points while maintaining overall valve timing stability.
Solution Approach 2:
The system dynamically adjusts the control shaft position by introducing deliberate fluctuations through reciprocating motion. Instead of maintaining a completely static target phase, the system allows controlled dynamic variations by reversing the actuator direction periodically. This dynamic approach prevents the static concentration of pressure that would otherwise occur at fixed gear mesh points and bearing contact areas.
2Measurement precision
If the electric actuator operates continuously to maintain target phase, then valve timing precision is improved, but bearing wear increases due to excessive biased force
Solution Approach 1:
The electric actuator performs periodic reciprocating motion by reversing its rotation direction when specific conditions are met (actual phase fluctuation within range and target phase maintained for predetermined period). This periodic reversal prevents continuous unidirectional pressure on the bearing, distributing the radial force over different bearing locations and time periods, thereby reducing localized wear while preserving phase control precision through feedback-based adjustments.
Solution Approach 2:
The system uses phase sensors to continuously monitor the actual phase and compares it with the target phase. Based on this feedback, the control unit determines when to reverse the actuator direction, ensuring that reciprocating motion occurs only when appropriate (when phase stability is achieved). This feedback mechanism maintains precision by making adjustments only when necessary, reducing unnecessary bearing stress while preserving accurate phase control.
Data Source
AI summary
The valve timing control unit includes a valve timing control mechanism that includes a driving rotary body, a driven rotary body, an electric motor and a deceleration gear each for setting the relative rotational phase of the driving rotary body and the driven rotary body, and a phase sensor unit that detects the actual phase of the driving rotary body and the driven rotary body. The valve timing control unit includes a controller that controls the electric motor to reduce a phase difference between the actual phase and a target phase, and the controller includes a swing controller that swings the target phase in vicinity of the target phase when the target phase is maintained and the actual phase having a fluctuation amount is held in a holding region, in which the fluctuation amount is less than a preset value.