Cam Phaser Backlash Compensation via Spring Biasing
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Solution Overview
Problem
Cam phasing systems face inaccuracies in controlling the phase angle due to backlash, which can result in over- or under-positioning, leading to inefficiencies in the rotational relationship between the crankshaft and camshaft.
Innovation Solution
The system includes a cam phaser with a sprocket hub driven by a crankshaft, a cradle rotor coupled to a camshaft, and a spider rotor that selectively locks and unlocks relative rotation, along with a biasing element like a spring to compensate for backlash by unidirectionally biasing the cradle rotor, allowing for accurate phase angle adjustment by accounting for backlash during actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If backlash compensation is implemented through control algorithms, then positioning accuracy is improved, but control complexity increases
Solution Approach 1:
The system pre-determines backlash values during manufacturing or initial operation and stores them in memory. The controller then uses these pre-stored backlash compensation values to adjust actuator positioning commands, eliminating the need for complex real-time backlash calculation algorithms while maintaining high positioning accuracy.
Solution Approach 2:
The patent introduces an intermediary backlash compensation mechanism that acts between the actuator and the cam phaser. This intermediary layer absorbs the complexity of backlash management by using pre-determined compensation values, simplifying the overall control system while improving positioning accuracy.
2Measurement precision
If mechanical backlash compensation mechanisms are added, then positioning accuracy is improved, but device complexity increases
Solution Approach 1:
The patent extracts the backlash compensation function from the mechanical structure and relocates it to the control system. By removing complex mechanical compensation mechanisms and implementing backlash compensation through software algorithms and pre-determined values, the system achieves high positioning accuracy while reducing mechanical complexity.
Solution Approach 2:
The system replaces potential mechanical backlash compensation mechanisms with an electronic control-based solution. The controller uses pre-determined backlash values to calculate corrected positioning commands, substituting complex mechanical compensation structures with a simpler electronic control approach that achieves the same positioning accuracy.
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 solution enables more precise control of the cam phasing system by compensating for backlash, ensuring accurate positioning of the camshaft relative to the crankshaft, thereby improving the system's operational accuracy and reducing errors in phase angle adjustments.
Implementation Method 1
at least one spring coupled between the spider rotor and the cradle rotor. The spring can be configured to bias the cradle rotor relative to the spider rotor in a first rotational direction to compensate for backlash within the cam phasing system
Data Source
AI summary
The present disclosure provides systems and methods to compensate for backlash within a cam phasing system. For example, compensating for backlash by commanding a predetermined amount of additional actuator movement to account for backlash within a cam phaser. According to some aspects, a spring is provided within a cam phaser to unidirectionally take up the backlash within the cam phasing system.