Camshaft Assembly Phaser Coupling Inversion
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Solution Overview
Problem
Conventional camshaft assemblies face challenges in establishing a secure coupling between the outer output member of the phaser and the end of the outer tube, particularly in SCP camshafts with large support bearings, which complicates the phase shift mechanism and drive transmission.
Innovation Solution
The solution involves reversing the connection between the phaser output members and the SCP camshaft by using a rotatable sleeve to connect the outer phaser output member to the inner shaft, allowing a drive coupling between the inner output member of the phaser and the outer tube, and employing a self-retaining fastener for axial positioning of the inner drive shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conventional approach is used to couple the inner shaft to the inner phaser output member and the outer tube to the outer phaser output member, then the phase shift mechanism can be implemented, but a secure coupling between the outer output member and the end of the outer tube cannot be established
Solution Approach 1:
The patent reverses the conventional coupling arrangement by connecting the outer phaser output member to the inner shaft and the inner phaser output member to the outer tube. This inversion resolves the coupling security issue by allowing the outer tube end to extend forward of the inner shaft end, providing a secure mounting location for the phaser while maintaining the phase shift functionality.
2Ease of operation
If the inner shaft is used to transmit torque for opening and closing engine valves, then valve operation is achieved, but radial forces on the inner shaft increase
Solution Approach 1:
The patent extracts the phaser drive function from the inner shaft by introducing a separate bearing sleeve that rotates with the outer tube and transmits phaser drive to the inner shaft through a pin. This separation allows the inner shaft to be optimized for valve operation torque transmission while the bearing sleeve handles the phaser drive, reducing radial forces on the inner shaft.
3Stability of the object's composition
If the bearing sleeve is fast in rotation with the outer tube, then support is provided for the camshaft, but the connection between phaser output members and camshaft cannot be reversed
Solution Approach 1:
The patent makes the bearing sleeve rotatable relative to the outer tube while maintaining its support function. This dynamic connection allows the bearing sleeve to rotate with the phaser drive while still providing stable support for the camshaft, enabling the reversed connection arrangement between phaser output members and camshaft components.
Data Source
AI summary
A camshaft assembly comprises an inner shaft 12 and an outer tube 14 surrounding and rotatable relative to the inner shaft. Two groups of cam lobes are mounted on the outer tube 14 , the first group of cam lobes 16 being fast in rotation with the outer tube 14 and the second group of lobes 26 being rotatably mounted on the outer surface of the tube 14 and connected for rotation with the inner shaft by means of pins 22 that pass with clearance through slots in the outer tube 14 . A sleeve 20 rotatably mounted on the outer tube 14 is connected to impart drive to the inner shaft 12 by means of a pin 24 passing with clearance through a circumferentially extending slot in the outer tube 14.