Recuperative Brake Torque Blending via Selective Hydraulic Circuit Control
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Solution Overview
Problem
Conventional recuperative brake systems with two brake circuits face issues in blending generator braking torque effectively, leading to increased pedal travel and uneven loading of storage volumes, which can result in reduced safety and shorter component lifespan.
Innovation Solution
The method involves selectively enabling hydraulic connections between the master brake cylinder and storage volumes of the brake circuits, allowing for controlled blending and non-blending modes to distribute loading uniformly, preventing simultaneous activation of both connections, and using existing valves to manage hydraulic connections and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If simultaneous enabling of two hydraulic connections between master brake cylinder and storage volumes is used for blending generator braking torque, then regenerative braking capability is improved, but pedal travel increases considerably in case of fault
Solution Approach 1:
The brake system is divided into two independent brake circuits, each with its own storage volume (accumulator). Instead of simultaneously enabling both hydraulic connections for blending, the system selectively enables only one hydraulic connection at a time. This segmentation allows the system to maintain regenerative braking capability while avoiding the fault condition where both accumulators would need to be filled, thus reducing excessive pedal travel.
Solution Approach 2:
The system dynamically switches between different operating modes (blending mode and non-blending mode) by controlling which hydraulic connection is enabled. This dynamic control allows the system to adapt to different conditions: using blending mode when generator braking torque is available and appropriate, and switching to non-blending mode when the generator cannot provide sufficient braking torque or when faults are detected, thereby optimizing both regenerative braking utilization and pedal travel characteristics.
2Loss of energy
If simultaneous enabling of two hydraulic connections is used for blending, then energy recovery is improved, but storage volumes experience uneven loading reducing their lifespan
Solution Approach 1:
The system employs periodic alternation between blending mode and non-blending mode operation. By switching which hydraulic connection is enabled in a periodic manner, the loading between the two storage volumes is distributed more evenly over time. This periodic action prevents one storage volume from being consistently over-loaded while the other remains under-utilized, thereby extending the overall lifespan of the storage volumes while maintaining effective energy recovery capability.
3Reliability
If generator braking torque blending is disabled due to fault conditions, then system reliability is improved against failures, but braking performance is reduced
Solution Approach 1:
The control device continuously monitors the operational status of the generator and brake circuits, and provides feedback control to determine whether to enable blending mode or non-blending mode. When the generator is functioning properly and conditions are appropriate, blending mode is enabled to optimize braking performance and energy recovery. When faults are detected or conditions are unsuitable, the system automatically switches to non-blending mode, ensuring reliable braking performance while maintaining system safety.
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 braking performance and safety by reducing pedal travel, extending the lifespan of storage volumes, and ensuring uniform loading, thereby reducing repair costs and improving the overall reliability of the brake system.
Implementation Method 1
a hydraulic connection between the master brake cylinder and the storage volume of the brake circuit controlled in the blending mode is enabled
Implementation Method 2
the pressure medium displaced from the master brake cylinder is transferred into the accumulators of the two brake circuits
Implementation Method 3
When the vehicle is decelerated using the electrical drive unit for simultaneously charging a battery
Data Source
AI summary
A method for blending a generator braking torque of a generator of a recuperative brake system having two brake circuits, including: controlling one of the at least two brake circuits of the brake system in a blending mode, a hydraulic connection between a master brake cylinder of the brake system and a storage volume of the brake circuit controlled in the blending mode being at least temporarily enabled, so that brake fluid is transferred from the master brake cylinder into the storage volume of the brake circuit controlled in the blending mode; and controlling another of the at least two brake circuits in a non-blending mode, a hydraulic connection between the master brake cylinder and a storage volume of the brake circuit controlled in the non-blending mode being interrupted during the non-blending mode. Also described is a control device for a recuperative brake system having two brake circuits.