Variable Valve Timing Control Apparatus Balancing Flow Resistance
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Solution Overview
Problem
Existing variable valve timing control apparatuses face challenges in quickly transitioning the relative rotational phase of the driven-side and driving-side rotating members after engine start-up due to imbalanced flow path resistance, leading to potential delays in valve timing, which can deviate from desired operation.
Innovation Solution
The apparatus incorporates a spider with distinct oil passages and a seal mechanism that allows atmospheric air to enter when pressure is lower than outside air pressure, ensuring quick phase transition by balancing flow path resistance and preventing prolonged negative pressure states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the supply path has high flow path resistance, then the working fluid can be supplied to the fluid pressure chamber, but the transition time is prolonged and the valve timing may delay
Solution Approach 1:
The supply path is segmented into two separate paths: a first supply path with a first flow control valve and a second supply path with a second flow control valve. This segmentation allows independent control of flow rates in each path, enabling the system to balance flow path resistance and reduce transition time while maintaining reliable valve timing.
Solution Approach 2:
The flow control valves are configured to dynamically adjust flow rates based on operating conditions. The first flow control valve has a larger opening area than the second, allowing the system to optimize fluid supply characteristics during different phases of operation, thereby reducing transition time while maintaining timing accuracy.
2Productivity
If the discharge path has low flow path resistance, then the working fluid can be discharged freely, but the flow path resistance becomes unbalanced with the supply path
Solution Approach 1:
The discharge path is designed with asymmetric flow resistance characteristics relative to the supply path. By configuring the discharge path to have lower flow path resistance than the supply path, the system achieves better drainage performance while the segmented supply path with adjustable flow control valves compensates for this asymmetry to maintain overall flow balance.
3Reliability
If the relative rotational phase is fixed at an intermediate position before start-up, then the engine can start safely, but the valve timing may deviate from desired operation after start-up
Solution Approach 1:
The system is pre-configured with a lock mechanism that fixes the driven-side rotating member at a predetermined rotational position (intermediate position) before engine start-up. This preliminary action ensures safe start-up conditions. After start-up, the control system activates the flow control valves to adjust fluid pressure and rotate the driven-side member to the desired operational position, thereby achieving both safety and efficiency.
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 configuration enables stable and timely transition of the relative rotational phase, ensuring the engine operates as intended by preventing prolonged negative pressure states and balancing flow resistance, thus maintaining desired valve timing.
Implementation Method 1
the seal mechanism allowing air to come in the at least one of the first oil passage and the second oil passage in a case where pressure inside the at least the one of the first oil passage and the second oil passage is lower than air pressure of the outside space
Data Source
AI summary
A variable valve timing control apparatus includes a driving-side rotating member, an driven-side rotating member, a cam shaft, a control valve switching supply and discharge of a working fluid relative to an advanced angle chamber and a retarded angle chamber, an advanced angle-side oil passage, a retarded angle-side oil passage, a spider provided with a first oil passage and a second oil passage, a seal mechanism partitioning between at least one of the first oil passage and the second oil passage, and an outside space, and the seal mechanism allows air to come in the at least one of the first oil passage and the second oil passage in a case where pressure inside the at least the one of the first oil passage and the second oil passage is lower than air pressure of the outside space.