Hybrid Vehicle Accessory Drive Torque Management
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Solution Overview
Problem
Conventional hybrid vehicles face limitations in regenerative braking efficiency due to maximum torque constraints in the front end accessory drive (FEAD) system, leading to parasitic losses and reduced hybrid performance.
Innovation Solution
A method to manage torque demand in the accessory drive system by determining and maintaining the drive belt torque threshold, reducing accessory component torque during regenerative events, and adjusting drive belt tension and wrap angle to prevent excessive torque load, thereby optimizing hybrid functionality without active control complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the drive belt torque is increased to improve regenerative braking efficiency, then the kinetic energy recovery is improved, but the drive belt experiences parasitic losses and torque transmission is reduced
Solution Approach 1:
The patent applies dynamics by making the accessory drive system controllable and adjustable rather than fixed. The electric motor in the FEAD system can dynamically adjust its torque output based on real-time operating conditions, allowing the system to optimize between regenerative energy recovery and preventing parasitic losses in the drive belt. This dynamic control enables the system to operate at maximum charging potential during recuperation events while staying within the maximum drive belt torque limits.
Solution Approach 2:
The patent utilizes parameter changes by monitoring and adjusting the torque parameter transmitted through the drive belt. The system changes the torque parameter dynamically based on the operating state - increasing torque during regenerative braking when conditions permit, and reducing torque when approaching the maximum drive belt torque threshold. This parameter adjustment resolves the contradiction by optimizing energy recovery while preventing parasitic losses.
2Power
If the maximum drive belt torque is increased to improve hybrid performance, then the torque assist capability is improved, but the drive belt service life is reduced
Solution Approach 1:
The patent implements feedback by continuously monitoring the torque transmitted through the drive belt and comparing it against the maximum drive belt torque threshold. The system uses this feedback information to adjust the electric motor torque output in real-time, ensuring that the torque assist capability is maximized without exceeding the drive belt's torque capacity. This feedback control prevents drive belt damage while maintaining optimal hybrid performance.
Solution Approach 2:
The patent applies preliminary action by establishing the maximum drive belt torque threshold before operation and using this predetermined limit to guide torque management decisions. The system proactively adjusts torque demand to prevent exceeding the threshold, rather than reacting after damage occurs. This preliminary setting of torque limits protects the drive belt service life while enabling adequate torque assist capability.
3Loss of energy
If the drive belt tension is increased to reduce parasitic losses, then the torque transmission efficiency is improved, but the device complexity and risk of drive belt damage increase
Solution Approach 1:
The patent applies self-service by using the electric motor's electronic control capability to manage torque demand internally without requiring external mechanical tensioning devices. The system self-regulates the torque transmitted through the drive belt by controlling the motor output, eliminating the need for complex mechanical tension control mechanisms. This reduces device complexity while still preventing parasitic losses through intelligent torque management.
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 approach enhances regenerative charging opportunities, reduces parasitic losses, and extends drive belt service life by maintaining torque within safe limits, ensuring efficient hybrid performance and accessory component operation.
Implementation Method 1
The maximum drive belt torque is the limit of torque that can be transmitted through the drive belt before the drive belt experiences parasitic losses (such as drive belt slip)
Implementation Method 2
a flexible drive element configured to transmit a torque load between the one or more accessory components and the motor generator
Data Source
AI summary
A method of operating an accessory drive system for a motor vehicle, wherein the accessory drive system includes one or more accessory components, a motor generator of the motor vehicle, and a flexible drive element configured to transmit a torque load between the one or more accessory components and the motor generator, includes determining a maximum permissible flexible drive element torque threshold, detecting an increase in torque demand on the flexible drive element, determining when the torque demand on the flexible drive element will exceed the flexible drive element torque threshold, and reducing the torque demand of one or more of the accessory components so that the flexible drive element torque threshold is not exceeded.