EMB Reducer Gear Ratio Selection for Torque Ripple NVH
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Solution Overview
Problem
In electro-mechanical brake (EMB) systems, overlapping torque ripple orders between motors and reducers lead to deteriorated noise, vibration, and harshness (NVH) characteristics due to similar frequency ripples during operation.
Innovation Solution
The EMB system selects a gear ratio for the reducer by excluding motor ripple generation orders based on the motor's specifications, including mechanical and electrical orders, and extends these orders to a preset range to filter out disadvantageous gear ratios, optimizing the reducer's design and reducing NVH issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a gear ratio is selected without considering motor ripple generation orders, then the design process is simpler and faster, but noise, vibration, and harshness (NVH) characteristics deteriorate due to overlapping ripples
Solution Approach 1:
The patent applies preliminary action by calculating and storing motor ripple generation orders during the design phase, before final gear ratio selection. The system pre-processes motor specification information to identify problematic ripple orders, then uses this pre-calculated data to guide gear ratio selection, avoiding NVH issues before they occur during operation.
Solution Approach 2:
The patent introduces an intermediary mechanism - a lookup table or database storing motor ripple generation orders - that mediates between motor specifications and gear ratio selection. This intermediary structure allows the system to reference pre-calculated ripple data during gear ratio selection without performing complex real-time calculations, thus simplifying the design process while maintaining NVH optimization.
2Object-affected harmful factors
If motor ripple generation orders are calculated and used to filter gear ratio candidates, then NVH characteristics improve, but the design process becomes more complex
Solution Approach 1:
The patent applies segmentation by dividing the design process into distinct stages: motor specification input, ripple order calculation, gear ratio candidate generation, and filtered selection. By segmenting the complex task of NVH-optimized gear ratio selection into manageable steps with clear interfaces, the system reduces overall design complexity while maintaining optimization capability.
Solution Approach 2:
The patent uses parameter changes by transforming motor specification parameters (number of poles, number of slots) into ripple generation order parameters through standardized formulas. This parameter transformation converts complex motor characteristics into a simplified ripple order representation that is easier to work with during gear ratio selection, reducing design process complexity.
3Manufacturing precision
If comprehensive ripple order analysis is performed including extended ranges, then NVH optimization is more thorough, but calculation time and complexity increase
Solution Approach 1:
The patent applies partial action by implementing an extended range parameter that allows selective expansion of the ripple order analysis beyond the basic calculation. Designers can choose to include only the essential ripple orders for quick assessment, or extend the analysis range for more thorough optimization, thus balancing calculation time against optimization precision based on project requirements.
Data Source
AI summary
A method for setting a gear ratio for an EMB system according to an exemplary embodiment of the present disclosure allows for filtering out gear ratios of a reducer that are disadvantageous for torque ripple or noise characteristics, by excluding the same/similar orders to an order of ripple that can be generated in the motor, when setting a gear ratio of the reducer, performs cause analysis more easily when the EMB system has a (noise, vibration, or harshness) NVH issue, since the motor and the reducer have their own unique order/frequency characteristics, and performs optimization of the reducer at an early design stage by selecting values that are available and not available as the gear ratio of the reducer.