Torque Transfer System with Torsion Bar Feedback
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Solution Overview
Problem
Conventional torque transfer systems in hybrid vehicles experience tooth hammer sound due to torque variation, particularly during engine startup, which is difficult to estimate and control in real-time, leading to increased costs with the use of torque meters.
Innovation Solution
A torque transfer system incorporating a resilient cushioning mechanism and a control unit that calculates and corrects the torque of the rotary electric machine based on the torsion angle between the engine and electric machine shafts, reducing torque variation and tooth hammer sound through a simple configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a torque meter is used to detect torque variation in real-time, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces a torsion bar as an intermediary element between the engine and the transmission system. This torsion bar mechanically transmits torque while its angular deformation serves as a natural indicator of torque variation. By measuring the rotation angle of the torsion bar instead of directly measuring torque, the system achieves accurate torque variation detection without requiring expensive torque meters, thus resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The patent replaces the need for complex electronic torque sensing systems with a simple mechanical torsion bar mechanism. The torsion bar's physical deformation under torque load provides a direct, passive measurement of torque variation that can be read through angle sensors, eliminating the need for sophisticated torque measurement equipment and reducing overall system complexity while maintaining measurement accuracy
2Device complexity
If map data based on crankshaft angle and coolant temperature is used to estimate torque variation, then device complexity is reduced, but measurement precision and reliability deteriorate under irregular engine operation
Solution Approach 1:
The patent implements a feedback mechanism where the actual rotation angle of the torsion bar is continuously measured and fed back to the control unit. This real-time feedback provides direct information about actual torque variation conditions, allowing the system to dynamically adjust rotary electric machine torque to compensate for detected variations. This feedback approach maintains low device complexity while significantly improving measurement precision and reliability under all engine operating conditions, including irregular operations where map-based estimation fails
3Object-affected harmful factors
If the resilient cushioning mechanism is added to reduce torque variation impact, then tooth hammer sound is reduced, but device complexity increases
Solution Approach 1:
The patent incorporates a torsion bar as a resilient cushioning element that is pre-installed in the torque transmission path between the engine and the transmission. This torsion bar acts as a shock absorber that beforehand cushions torque variations and prevents them from reaching the gear mechanism, thereby eliminating tooth hammer sound. The cushioning effect is built into the mechanical structure itself, achieving noise reduction without adding complex active control systems or multiple additional components
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 system effectively suppresses tooth hammer sound by stabilizing the torsion angle of the resilient cushioning mechanism, thereby reducing the impact of torque variation and enhancing the operational stability of the torque transfer process.
Implementation Method 1
The resilient cushioning mechanism has a resilient deformable part coupled to the other end of the first shaft
Data Source
AI summary
A first shaft has one end coupled to an engine. A damper has a spring coupled the other end of the first shaft. A second shaft has one end coupled to the spring. A third shaft rotates in correspondence to a final output shaft. A fourth shaft has one end coupled to a first rotary electric machine. A power split mechanism is provided among the second shaft, the third shaft and the fourth shaft and transfers torque among the second shaft, the third shaft and the fourth shaft. A control unit calculates a torque correction value for the rotary electric machine based on information indicating torsion angle of the damper and corrects the torque of the rotary electric machine based on a calculated torque correction value.