Electrohydraulic Brake Redundancy Using EPB Slip Control
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Solution Overview
Problem
Conventional electronic brake systems experience instability and wheel slip during backup braking, particularly affecting rear wheels, which can lead to accidents due to inadequate braking force distribution and energy recovery strategies that prioritize front wheels.
Innovation Solution
An electrohydraulic brake system incorporating a redundancy control unit that utilizes electronic parking brakes for slip control and regenerative braking to enhance rear-wheel braking force, employing the slow ramp up function for increased braking power and real wheel unlocker for slip management, ensuring stable vehicle braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If hydraulic control is performed only on the front wheels during backup braking to increase energy recovery, then the proportion of regenerative braking is increased, but the braking force and stability of the vehicle deteriorate
Solution Approach 1:
The brake system divides the braking function into two independent parts: the main brake assembly for front wheels providing hydraulic braking force, and the electronic parking brake for rear wheels providing auxiliary braking force. This segmentation allows each component to operate independently, enabling the system to maintain vehicle stability while maximizing regenerative braking on the front wheels during backup braking mode
Solution Approach 2:
The system applies different braking strategies to different parts of the vehicle: front wheels receive hydraulic braking control optimized for energy recovery, while rear wheels receive electronic parking brake control optimized for maintaining stability and preventing wheel slip. This local differentiation resolves the contradiction by allowing each wheel group to serve its specific function
2Productivity
If hydraulic control is performed only on the front wheels during backup braking, then regenerative braking proportion is increased, but wheel slip occurs and braking stability deteriorates
Solution Approach 1:
The electronic parking brake on the rear wheels acts in advance to prevent wheel slip by providing counteracting braking force. When the main brake assembly applies hydraulic braking to the front wheels for energy recovery, the electronic parking brake simultaneously applies braking force to the rear wheels to counteract any tendency toward wheel slip, thereby preventing the harmful effect before it occurs
Solution Approach 2:
The system converts the potential harm of wheel slip into a benefit by using the electronic parking brake to deliberately apply controlled braking force to the rear wheels. This controlled application of the electronic parking brake, which might seem like an additional constraint, actually prevents wheel slip and improves overall braking stability while allowing maximum regenerative braking on the front wheels
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 achieves stable vehicle braking by securing 0.8 g of braking power on front wheels and additional rear-wheel braking force, effectively preventing wheel slip and supplementing braking force through regenerative braking, thus improving safety and efficiency.
Implementation Method 1
The electronic parking brakes are configured to generate a braking force to one of the front wheels and the rear wheels
Implementation Method 2
supplementing the insufficient braking force with the regenerative brake force
Data Source
AI summary
According to at least one embodiment, the present disclosure provides an electrohydraulic brake system including main brake assemblies, electronic parking brakes (EPBs), a main control unit, and a redundancy control unit (RCU). The main brake assemblies generate a braking force in one or more front wheels and one or more rear wheels of a vehicle. The electronic parking brakes (EPBs) generate a braking force to one of the front wheels and rear wheels. The main control unit is configured to control the operation of the main brake assembly. The redundancy control unit (RCU) is configured to control the operation of the electronic parking brake. Here, the redundancy control unit performs, upon determining that a malfunction occurs in a braking function of the main control unit, a slip control on the vehicle by using the electronic parking brake based on signals from one or more wheel speed sensors.