Automotive Braking Device Pressure Accumulator Control
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Solution Overview
Problem
Hybrid vehicle brake systems face challenges in combining deceleration effects from active units and wheel brakes, requiring driver compensation for variable deceleration, and existing solutions are complex and lack reliability and simplicity.
Innovation Solution
A dual-circuit brake system with a conventional hydraulic brake circuit and a secondary brake circuit that functions as a brake-by-wire system, using a pressure accumulator and control device to blend deceleration effects from active units with wheel brakes, ensuring constant deceleration and high reliability, with the secondary circuit falling back to hydraulic mode in failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a hybrid vehicle brake system combines deceleration effects from active units (generators) and wheel brakes, then energy recovery is enabled and brake protection is achieved, but the deceleration effect becomes variable requiring driver compensation
Solution Approach 1:
A control device acts as an intermediary between the driver's braking request and the actual braking execution. The control device receives the driver's deceleration request and automatically distributes the braking force between the active units and wheel brakes, eliminating the need for the driver to manually compensate for variable deceleration effects while maintaining energy recovery functionality
2Reliability
If a dual-circuit brake system with brake-by-wire secondary circuit is implemented, then constant deceleration and high reliability are achieved, but device complexity increases
Solution Approach 1:
The brake system is segmented into two independent circuits: a conventional hydraulic brake circuit for direct driver control and a secondary brake-by-wire circuit for automated control. This segmentation allows each circuit to have specialized functions, improving overall reliability through redundancy while managing complexity by dividing the system into modular, independently controllable units
Solution Approach 2:
The system changes the control parameter from direct hydraulic pressure control to electronic control with a control device that manages pressure accumulation and release. This parameter change enables more precise and reliable control of deceleration while the electronic control system manages the complexity of the dual-circuit configuration
3Productivity
If the secondary brake circuit is decoupled from the master brake cylinder during partial braking, then blending of deceleration effects is optimized, but hydraulic fluid management becomes more complex
Solution Approach 1:
A pressure accumulation device is used to pre-accumulate hydraulic fluid under pressure before it is needed. During partial braking, the secondary circuit can be decoupled from the master brake cylinder and receive pressurized fluid from the accumulation device, enabling optimized deceleration blending without the complexity of real-time hydraulic fluid management during braking events
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 provides a simple, reliable, and constant braking experience by blending deceleration effects from active units with wheel brakes, maintaining full braking capability and minimizing driver compensation for variable deceleration, while optimizing energy recovery in hybrid vehicles.
Implementation Method 1
a pressure accumulator (26a) which is connectable to a pressure side of the second brake circuit (2) by means of an accumulator control valve (26b)
Implementation Method 2
the filling valve (18a) is opened, the accumulator control valve (26b) is opened and the brake pressure build-up valves (11a, 12a) are closed and the hydraulic pump (15a) of the second brake circuit (2) is operated to fill the pressure accumulator (26a)
Data Source
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AI summary
The invention relates to a braking device for a motor vehicle, comprising a first and a second hydraulic brake circuit (1, 2), wherein the second brake circuit (2) is decoupled from the master brake cylinder (9) during partial breaking operations and is operated by means of a pressure accumulator (26a), especially controlled by a control device (22) which takes into consideration any additional decelerating effect caused by an effective unit (20), for example a generator.