Compound Brake System Hydraulic Electric Control Accuracy
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Solution Overview
Problem
Existing brake systems with hydraulic mechanisms on the front wheels and electric mechanisms on the rear wheels face challenges in controlling braking force accuracy due to instability in hydraulic pressure during low-speed rotation and liquid compression, leading to discomfort for occupants, especially at low pressure driving conditions.
Innovation Solution
A brake control device that adjusts the braking force of both hydraulic and electric brake systems based on a required braking force, using multiple control modes to match the sum of braking forces from both systems, and incorporates compensation calculations to prevent wheel lock and improve control accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a hydraulic mechanism is used on the front wheel side, then braking force can be generated, but control accuracy of braking force is low especially at low pressure driving due to instability of flow rate during low-speed rotation, low control accuracy of valve for adjusting pump discharge pressure, and influence of liquid compression
Solution Approach 1:
The patent combines hydraulic brake mechanism and electric brake mechanism into a compound brake system. The electric brake mechanism compensates for the low control accuracy of the hydraulic mechanism at low pressure conditions, achieving accurate braking force control across all pressure ranges by merging the advantages of both mechanisms.
Solution Approach 2:
The control device dynamically changes the operating parameters of the hydraulic pump (rotation speed, discharge amount) and electric brake (drive force) based on the required braking force. By adjusting these parameters in real-time, the system maintains high control accuracy even at low pressure conditions where the hydraulic mechanism alone would be insufficient.
2Force
If pump or valve is driven in accordance with required braking force to generate hydraulic pressure, then braking force is produced, but sudden increase in hydraulic pressure immediately after braking request or hydraulic pressure remaining even when required braking force is zero occurs, causing braking force to differ from driver's assumption
Solution Approach 1:
The control device continuously monitors the actual braking force and compares it with the required braking force. Based on this feedback, it adjusts the hydraulic pressure and electric brake drive force to eliminate deviations, preventing sudden pressure increases and ensuring the braking force matches the driver's intent throughout the braking process.
Solution Approach 2:
The control device performs preliminary calculations to determine the appropriate hydraulic pressure and electric brake drive force before actuation. This preliminary action prevents sudden pressure increases by smoothly initiating braking force application from the beginning, ensuring predictable and reliable braking behavior.
3Force
If hydraulic mechanism and electric mechanism are controlled based on control amount such as required braking force, then braking force is generated, but responsiveness to fluctuation of required braking force during brake operation is insufficient
Solution Approach 1:
The control device dynamically adjusts the contribution ratio between the hydraulic brake mechanism and electric brake mechanism based on the rate of change of required braking force. When rapid changes are detected, the system increases the response speed by adjusting pump rotation speed and valve opening degree, maintaining high responsiveness throughout the braking operation.
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 enables accurate control of braking force, enhancing riding comfort and reducing driver discomfort by smoothing braking force changes and improving responsiveness to minute control requests.
Implementation Method 1
a hydraulic mechanism constituted by a pump and a valve on the front wheel side
Implementation Method 2
there is a configuration which has no mechanical connection using hydraulic pressure between a hydraulic mechanism
Implementation Method 3
an electric mechanism on a rear wheel side of a vehicle
Data Source
AI summary
A brake system capable of accurately controlling a braking force includes a first and second brake devices that have different control accuracies, and a brake control device that controls a braking force of the first and second braking devices according to a required braking force. The brake control device has a first control mode in which the braking force of the first brake device is controlled to be smaller than the braking force of the second brake device, and a second control mode in which the braking force of the first brake device is increased rather than the first control mode. The second brake device is controlled so that a sum of the braking force of the first brake device and the braking force of the second brake device matches the required braking force.