Wheel Brake Pressure Control with Solenoid Loss Compensation
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Solution Overview
Problem
Existing braking control devices for vehicles face challenges in improving the responsiveness of wheel pressure increase, particularly due to pressure losses in solenoid valves during rapid braking requests.
Innovation Solution
A braking control device that includes a pressure adjustment unit using an electric motor to generate servo pressure, solenoid valves in the hydraulic pressure transmission path, and a controller that calculates and compensates for pressure losses in the solenoid valves to determine a target pressure, thereby enhancing the responsiveness of wheel pressure increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If solenoid valves are used in the hydraulic pressure transmission path to control wheel pressure independently for each wheel, then braking control functionality is improved, but pressure loss occurs in the solenoid valves causing delayed wheel pressure increase
Solution Approach 1:
The controller calculates the pressure loss in solenoid valves in advance based on the relationship between flow rate and pressure loss, and determines the target pressure by adding this calculated pressure loss to the instruction pressure. This preliminary compensation action ensures that the actual wheel pressure reaches the desired level despite the inherent pressure loss in the solenoid valves.
Solution Approach 2:
The controller continuously monitors the actual wheel pressure and compares it with the target pressure, then adjusts the servo pressure output from the pressure adjustment unit accordingly. This closed-loop feedback control ensures accurate wheel pressure control by compensating for pressure losses in real-time.
2Adaptability or versatility
If solenoid valves are used in the hydraulic pressure transmission path, then braking control functionality is improved, but wheel pressure increase responsiveness deteriorates
Solution Approach 1:
The controller calculates the pressure loss in solenoid valves in advance based on the relationship between flow rate and pressure loss, and determines the target pressure by adding this calculated pressure loss to the instruction pressure. This preliminary compensation action ensures that the actual wheel pressure reaches the desired level despite the inherent pressure loss in the solenoid valves.
Solution Approach 2:
The controller dynamically adjusts the target pressure parameter based on the calculated pressure loss, which varies with flow rate conditions. By changing the target pressure parameter in response to varying flow conditions, the system maintains optimal responsiveness across different operating scenarios.
3Ease of operation
If target pressure is determined without considering pressure loss, then control simplicity is maintained, but wheel pressure increase responsiveness deteriorates
Solution Approach 1:
The controller calculates the pressure loss in solenoid valves in advance based on the relationship between flow rate and pressure loss, and determines the target pressure by adding this calculated pressure loss to the instruction pressure. This preliminary compensation action ensures that the actual wheel pressure reaches the desired level despite the inherent pressure loss in the solenoid valves.
Solution Approach 2:
The system replaces complex mechanical pressure compensation mechanisms with electronic calculation and control. The controller uses computational algorithms to calculate pressure loss and adjust target pressure, substituting mechanical complexity with electronic intelligence while maintaining control simplicity from the operator's perspective.
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 solution effectively improves the responsiveness of wheel pressure increase by anticipating and compensating for pressure losses in solenoid valves, ensuring faster and more reliable braking performance.
Implementation Method 1
a pressure adjustment unit CA that adjusts a wheel pressure Pw of a wheel cylinder CW by a servo pressure Pu generated by using an electric motor MA as a power source
Implementation Method 2
a solenoid valve (e.g., inlet valve VI) provided in a hydraulic pressure transmission path (HS) from the servo pressure (Pu) to the wheel pressure (Pw)
Data Source
AI summary
A braking control device includes a pressure adjustment unit that adjusts a wheel pressure Pw of a wheel cylinder by a servo pressure Pu generated using an electric motor as a power source, a solenoid valve provided in a hydraulic pressure transmission path from the servo pressure Pu to the wheel pressure Pw, and a controller that controls the pressure adjustment unit. The controller calculates a pressure loss Pd in the solenoid valve based on an instruction pressure Ps calculated from a braking request amount Bs and the wheel pressure Pw. Then, the controller determines a target pressure Pt by adding the pressure loss Pd to the instruction pressure Ps, and controls the pressure adjustment unit based on the target pressure Pt.