Recuperative Brake System Fluid Routing for Pedal Feel
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Solution Overview
Problem
Existing recuperative braking systems in vehicles face limitations in regenerative efficiency and driver feedback, particularly during transitions between regenerative and hydraulic braking, leading to suboptimal energy recovery and increased pollutant emissions.
Innovation Solution
A method and control device that enable 'force blending' and 'volume blending' in a recuperative braking system, allowing for seamless transitions between regenerative and hydraulic braking while maintaining standard brake pedal feel, by controlling brake fluid flow and pressure distribution within the braking system, independent of the brake booster's operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regenerative braking is used to charge the battery, then energy recovery is improved, but the driver experiences abnormal brake pedal feel and reduced braking comfort
Solution Approach 1:
A storage chamber is introduced as an intermediary component between the master brake cylinder and wheel brake cylinders. During regenerative braking, brake fluid is diverted to the storage chamber instead of directly to the wheels, maintaining hydraulic pressure in the master cylinder to preserve normal pedal feel while enabling energy recovery through the electric drive.
Solution Approach 2:
The system dynamically changes the routing parameter of brake fluid flow based on operating conditions. A switching mechanism alters the fluid path between direct hydraulic braking and regenerative braking modes, allowing the system to maintain optimal pedal feel characteristics while maximizing energy recovery when conditions permit.
2Loss of energy
If brake fluid is diverted to storage chamber during regenerative braking, then regenerative efficiency is improved, but hydraulic braking torque is reduced
Solution Approach 1:
The system dynamically adjusts the distribution of brake fluid between the storage chamber and wheel brake cylinders based on real-time braking demands and regenerative opportunities. The switching mechanism enables continuous adaptation between pure regenerative braking, pure hydraulic braking, and blended modes to optimize both energy recovery and braking performance.
Solution Approach 2:
The brake fluid distribution system serves multiple functions: it enables regenerative braking by diverting fluid to the storage chamber, maintains hydraulic braking capability by allowing fluid flow to wheels when needed, and provides blended braking modes. This multi-functional design resolves the contradiction between energy recovery and braking torque availability.
3Force
If standard hydraulic braking is used, then braking torque is maintained, but energy consumption increases and emissions are higher
Solution Approach 1:
The control system continuously monitors braking demands, vehicle speed, battery charge state, and other parameters to determine the optimal braking strategy. This feedback mechanism enables the system to maximize regenerative braking opportunities while maintaining required braking torque, thereby reducing energy consumption and emissions compared to conventional hydraulic braking alone.
4Ease of operation
If brake booster is used to assist braking, then ease of operation is improved, but system complexity and cost increase
Solution Approach 1:
The existing brake booster is made multi-functional by integrating it with the regenerative braking system through the switching mechanism and storage chamber. The same brake booster provides assistance for both traditional hydraulic braking and regenerative braking operations, eliminating the need for separate systems and reducing overall complexity despite the added functionality.
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 efficiency, reduces energy consumption and emissions, and provides improved braking comfort by maintaining the setpoint braking torque requested by the driver, even when regenerative braking torque is limited, without the need for a vacuum brake booster, thus expanding the system's functionality and cost-effectiveness.
Implementation Method 1
the master brake cylinder counteracting force/master brake cylinder reaction force... increases
Implementation Method 2
the hydraulic braking torque exerted by the at least one wheel brake cylinder
Data Source
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AI summary
The invention relates to a method for operating a recuperative brake system of a vehicle, having the following steps: actuating at least one valve (70a, 70b, 78a, 78b, 79a, 79b) of a brake circuit (50, 52) prior to and/or during an operation of a generator of the brake system such that brake fluid is moved out of the master brake cylinder (62) and/or the at least one brake circuit (50, 52) into at least one storage volume (82a, 82b). A target force differential variable with respect to a boosting force (Fv) exerted by a brake booster (68) is set while taking into consideration generator/brake torque information (14), a measured or estimated master brake cylinder pressure variable (16), and/or an evaluation variable derived from at least the generator/braking torque information (14) or the master brake cylinder pressure variable (16), and the brake booster (68) is actuated while taking into consideration the set target pressure differential variable such that the booster force (Fv) is varied by an actual force differential corresponding to the target force differential variable. The invention likewise relates to a control device (100) for a recuperative brake system of a vehicle.