Electric Camshaft Phaser Spring Locking Mechanism
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Solution Overview
Problem
Electric camshaft phasers experience 'drift' of the rotor relative to the stator after engine shutdown due to residual torque and inherent friction, making it difficult to predict the final control angle and reducing the service life of lever springs.
Innovation Solution
A camshaft phaser design that includes a stator and rotor with a spring mechanism, where the spring is non-rotatably connected to either the stator or rotor, and features a radially outwardly extending protrusion with an indent, allowing the spring to engage and maintain the rotor's position after engine shutdown, providing a known control angle upon startup and minimizing drag during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lever springs are used to lock the rotor, then the rotor can be locked in position, but the constant flexing of the lever springs reduces their service life
Solution Approach 1:
The spring is pre-positioned in a relaxed state away from the radially inwardly extending protrusion during operation. Before shutdown, the control system commands the spring to engage with the protrusion, locking the rotor in a predetermined position. This preliminary engagement prevents drift without requiring continuous flexing of the spring during operation, thereby extending service life while maintaining locking reliability.
2Stability of the object's composition
If the spring constantly contacts the protrusion to maintain position, then the rotor position is stable, but frictional drag increases during operation
Solution Approach 1:
The spring-protrusion engagement system is designed to be dynamic rather than static. During operation, the spring maintains a relaxed position with minimal or no contact to the protrusion, allowing free rotation with minimal frictional drag. Upon shutdown, the spring is commanded to engage with the protrusion to lock the rotor position. This dynamic engagement/disengagement cycle provides position stability when needed while minimizing energy loss during operation.
3Device complexity
If no locking mechanism is used, then the device complexity is reduced, but the rotor drifts after engine shutdown
Solution Approach 1:
The invention extracts only the essential locking function from complex multi-component locking mechanisms. A single spring element with a simple radially inwardly extending protrusion provides the necessary locking capability. The spring is non-rotatably connected to the rotor and engages with a corresponding feature on the stator, creating a minimal yet effective locking system that prevents drift without adding excessive complexity.
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 spring mechanism effectively locks the rotor in a predetermined position post-shutdown, preventing drift and extending the service life of the camshaft phaser by reducing frictional drag during operation.
Implementation Method 1
a spring non-rotatably connected to the rotor. In a first circumferential position of the rotor with respect to the stator: no portion of the spring is disposed in the indent; and in a second circumferential position of the rotor with respect to the stator, a first portion of the spring is disposed in the indent
Implementation Method 2
The rotor is arranged to be connected to an electric motor. The electric motor is arranged to rotate the rotor with respect to the stator
Implementation Method 3
a stator arranged to receive rotational torque from an engine
Data Source
AI summary
A camshaft phaser, including: a stator to receive rotational torque from an engine and including a radially inwardly facing surface and a slot in the radially inwardly facing surface; a rotor to non-rotatably connect to a camshaft, to be connected to an electric motor and including a first radially outwardly extending protrusion; and a spring non-rotatably connected to the stator and including a first portion disposed in the slot. The electric motor is arranged to rotate the rotor with respect to the stator. In a first circumferential position of the rotor with respect to the stator: no portion of the spring is disposed in the indent; and a second portion of the spring extends radially inwardly past the radially inwardly facing surface. In a second circumferential position of the rotor with respect to the stator, the second portion of the spring is disposed in the indent.