Harmonic Drive Camshaft Phaser Anti-Rotation Mechanism
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Solution Overview
Problem
The existing electric variable cam phaser (eVCP) systems face damage during attachment to the camshaft due to friction-induced relative movement between the circular and dynamic splines, which can cause undesired torque and damage to the harmonic drive unit.
Innovation Solution
An anti-rotation mechanism is introduced, featuring a pin that temporarily fixes the circular spline to the dynamic spline, preventing relative rotation between them during attachment, thereby preventing damage to the harmonic drive unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the eVCP is attached to the camshaft using a bolt that extends axially through the eVCP and threadably engages the camshaft, then the eVCP can be securely fastened to the camshaft, but friction is generated between the head of the bolt and the eVCP which applies torque causing undesired relative movement between the circular spline and the dynamic spline
Solution Approach 1:
The patent applies preliminary anti-action by providing anti-rotation means (such as pins or keys) that prevent relative rotation between the circular spline and dynamic spline before the harmful friction torque can occur during bolt tightening. This preliminary preventive measure counteracts the potential harmful effect before it manifests.
Solution Approach 2:
The patent introduces an intermediary element (the anti-rotation means, such as pins or keys) that mediates between the circular spline and dynamic spline to prevent relative movement. This intermediary component absorbs or prevents the harmful relative motion that would otherwise occur during attachment.
2Stability of the object's composition
If the housing of the eVCP is prevented from rotating by the chain, belt, or gearing connected to the crankshaft, then the housing remains stationary during attachment, but the friction torque from the bolt head causes relative movement between the circular spline and dynamic spline which can damage the harmonic drive unit
Solution Approach 1:
The anti-rotation means is installed beforehand to prevent relative rotation between the circular spline and dynamic spline before the bolt tightening process begins. This preliminary protective measure ensures that when friction torque is applied during attachment, the harmonic drive unit is already protected from damaging relative movement.
Solution Approach 2:
The patent provides beforehand cushioning by incorporating anti-rotation means that act as a protective barrier against the harmful effects of friction torque. This preliminary protection cushioning prevents the harmonic drive unit from being damaged during the attachment process.
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 anti-rotation mechanism allows for secure attachment of the eVCP to the camshaft without damaging the harmonic drive unit, ensuring reliable operation and extending the lifespan of the eVCP system.
Implementation Method 1
a flexspline disposed radially within the circular spline and the dynamic spline, a wave generator disposed radially within the flexspline
Data Source
AI summary
A camshaft phaser includes a housing with a harmonic gear drive unit disposed therein. The harmonic gear drive unit includes a circular spline and a dynamic spline, a flexspline disposed radially within the circular spline and the dynamic spline, a wave generator disposed radially within the flexspline, and a rotational actuator connectable to the wave generator. One of the circular spline and the dynamic spline is fixed to the housing. A hub is rotatably disposed radially within the housing and attachable to the camshaft and fixed to the other of the circular spline and the dynamic spline. An anti-rotation means is provided for temporarily fixing the circular spline to the dynamic spline in order to prevent relative rotation therebetween when the hub is being attached to the camshaft. The anti-rotation means prevents damage to the harmonic gear drive unit while the camshaft phaser is being installed onto the camshaft.