Cam Phasing Helix Locking Design for Overshoot Control
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Solution Overview
Problem
Current mechanical cam phasing systems in internal combustion engines face challenges in controlling the speed and stop position of the phaser, leading to overshooting or undershooting due to large cam torque pulses, resulting in continuous cycling or the need for fast control mechanisms.
Innovation Solution
A cam phasing system with a helix locking design that includes a crank coupling component, a cam coupling component with a helical feature, and an actuator to apply an input force through a compliance mechanism, allowing for precise control of the rotational relationship between the camshaft and crankshaft by frictionally locking during rotary torque events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a mechanical cam phasing system uses cam torque pulses to rotate the phaser, then the phaser can rotate in the direction of the torque pulse, but the speed and stop position of the phaser cannot be controlled directly
Solution Approach 1:
A motor is introduced as an intermediary actuator between the control system and the phaser mechanism. The motor provides controlled rotational force to drive the phaser, replacing direct mechanical actuation by cam torque pulses. This intermediary allows precise control of phaser speed and position while avoiding the overshooting problems of direct mechanical actuation.
Solution Approach 2:
The patent replaces the purely mechanical cam torque-based actuation system with an electromechanical system using a motor. This substitution enables electronic control of the phaser, providing direct control over speed and position that was not achievable with mechanical torque pulses alone.
2Device complexity
If a mechanical cam phasing system relies on cam torque pulses, then the system structure is simple, but the control speed must be very fast to prevent continuous cycling
Solution Approach 1:
The motor-based actuation system replaces the fast-cycling mechanical torque pulse system. The motor provides smooth, controlled rotation without the need for high-speed on/off cycling, reducing the control bandwidth requirements while maintaining or improving phasing accuracy.
3Ease of operation
If hydraulic or electronic actuators are used to actuate the phaser, then direct control of phaser rotation is achieved, but the number of components and system complexity increases
Solution Approach 1:
The patent uses a motor (electromechanical actuator) instead of hydraulic actuators. This choice reduces system complexity by eliminating hydraulic fluid, hoses, pumps, and associated sealing requirements, while still providing direct control capability. The motor can be directly coupled to the phaser mechanism with fewer intermediate components.
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
The system enables precise control of the rotational relationship between the camshaft and crankshaft, reducing overshooting and undershooting, and allowing for efficient phase changes by transferring rotary torque into axial forces, thereby improving the accuracy and reliability of cam phasing.
Implementation Method 1
The interaction between the first helical feature and the second helical feature is configured to frictionally lock the cam coupling component to the input component during rotary torque events
Data Source
AI summary
Cam phasing systems and methods are provided. In particular, a cam phasing system is provided that includes a reduced number of components when compared to current mechanical cam phasing systems. The cam phasing system includes a helix locking design that is configured to frictionally lock a helix rod during cam torque pulses.