Valve Timing Control Using Segmented Speed Reducers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing valve timing control systems for internal combustion engines face a challenge in balancing the need for improved operational responsiveness of intake valve timing control devices with the requirement for enhanced phase holding performance of exhaust valve timing control devices, as the same speed reducers are used for both, leading to contradictory performance trade-offs.
Innovation Solution
The system employs distinct speed reducers for intake and exhaust valve timing control devices, with the intake valve timing control device having a friction-reduced speed reducer and the exhaust valve timing control device having a friction-increased speed reducer, and utilizing different types of electric motors (brushless for intake and brush-equipped for exhaust) to optimize responsiveness and holding performance respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same speed reducer is used for both intake and exhaust valve timing control devices, then the device complexity is reduced, but the operational responsiveness of intake valve timing control deteriorates when phase holding performance is prioritized, and vice versa
Solution Approach 1:
The patent divides the valve timing control system into two separate subsystems: an intake valve timing control device and an exhaust valve timing control device, each with its own dedicated speed reducer. This segmentation allows each speed reducer to be optimized independently for its specific function, resolving the contradiction between operational responsiveness and phase holding performance.
Solution Approach 2:
The patent applies different friction characteristics to different parts of the system: the intake valve timing control speed reducer is designed with lower friction to prioritize operational responsiveness, while the exhaust valve timing control speed reducer is designed with higher friction to prioritize phase holding performance. This local differentiation resolves the contradiction by allowing each subsystem to have optimized properties for its specific requirements.
2Reliability
If the speed reducer friction is increased to improve phase holding performance, then the phase holding performance is improved, but the operational responsiveness deteriorates
Solution Approach 1:
The patent separates the valve timing control into independent intake and exhaust systems, each with dedicated speed reducers. This allows the exhaust speed reducer to be optimized for phase holding performance without compromising intake valve operational responsiveness.
Solution Approach 2:
The patent applies different friction characteristics to different speed reducers: higher friction in the exhaust speed reducer for improved phase holding performance, and lower friction in the intake speed reducer for improved operational responsiveness. This local differentiation resolves the contradiction by allowing each subsystem to have optimized properties for its specific requirements.
3Speed
If the speed reducer friction is decreased to improve operational responsiveness, then the operational responsiveness is improved, but the phase holding performance deteriorates
Solution Approach 1:
The patent divides the valve timing control system into separate intake and exhaust subsystems with dedicated speed reducers. This segmentation allows the intake speed reducer to be optimized for operational responsiveness without compromising exhaust valve phase holding performance.
Solution Approach 2:
The patent applies different friction characteristics to different speed reducers: lower friction in the intake speed reducer for improved operational responsiveness, and higher friction in the exhaust speed reducer for improved phase holding performance. This local differentiation resolves the contradiction by allowing each subsystem to have optimized properties for its specific requirements.
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 allows for improved operational responsiveness of the intake valve timing control and enhanced phase holding performance of the exhaust valve timing control, effectively reconciling the contradictory requirements.
Implementation Method 1
the first speed reducer of the intake valve timing control device is configured to have a friction less than a friction of the second speed reducer of the exhaust valve timing control device
Implementation Method 2
the second speed reducer of the exhaust valve timing control device is configured to have a friction greater than the first speed reducer
Data Source
AI summary
In a valve timing control system of an internal combustion engine employing both an electric-motor-driven intake valve timing control device for changing intake valve timing and an electric-motor-driven exhaust valve timing control device for changing exhaust valve timing, the intake valve timing control device includes a less-friction roller speed reducer having a toothed gear and configured to transmit torque by repeated relocations of each of rollers rolling and relocating from one of two adjacent teeth of the toothed gear to the other. In contrast, the exhaust valve timing control device includes a planetary-gear speed reducer having a friction greater than a friction of the roller speed reducer and configured to transmit torque by meshed-engagement of toothed gears in mesh with each other.