Recirculation Pump Control for Hydraulic Brake Noise Reduction
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Solution Overview
Problem
Hydraulic braking systems with antilocking systems experience noise emission due to the activation of the recirculation pump, which is linked to the control of hydraulic fluid pressure in wheel brake units.
Innovation Solution
The method involves controlling the target pump speed of the recirculation pump to maintain a constant volume of hydraulic fluid in the storage chamber by adjusting the control frequency of the antilocking system and inlet/outlet valve operations, reducing noise by maintaining a virtually static equilibrium and ensuring a sufficient buffer volume based on friction coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the recirculation pump is activated to convey hydraulic fluid from the storage chamber back into the brake circuit, then the hydraulic fluid is recirculated, but noise emission increases
Solution Approach 1:
The recirculation pump is activated periodically rather than continuously. The control device activates the pump only when the storage chamber contains a sufficient buffer volume of hydraulic fluid, creating a periodic on-off operation pattern that reduces noise while maintaining recirculation functionality
Solution Approach 2:
The control device monitors the volume of hydraulic fluid in the storage chamber and adjusts pump activation based on this parameter. When the buffer volume falls below a threshold, the pump is activated to restore the volume, creating a parameter-based control strategy that reduces unnecessary pump operation and associated noise
2Quantity of substance
If the pump speed is increased to ensure sufficient fluid recirculation, then the buffer volume is maintained, but noise level increases
Solution Approach 1:
The recirculation pump operates at partial capacity rather than maximum speed. The pump is activated only enough to restore the buffer volume to the sufficient level, avoiding excessive recirculation that would increase noise without providing additional benefit
Solution Approach 2:
The control device continuously monitors the volume of hydraulic fluid in the storage chamber and uses this feedback to control pump activation. This closed-loop control ensures the pump operates only when necessary to maintain the buffer volume, minimizing noise while ensuring sufficient fluid recirculation
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 minimizes noise emission by maintaining a low and stable pump speed, ensuring continuous fluid recirculation and reducing the noise level caused by the recirculation pump, while maintaining sufficient hydraulic fluid in the storage chamber for optimal brake pressure regulation.
Implementation Method 1
the outflowing hydraulic fluid is retained in a storage chamber, which is situated in a brake circuit of the braking system, and from which the fluid is conveyed back into the brake circuit through activation of a recirculation pump
Implementation Method 2
outlet valves are opened to allow hydraulic fluid to flow out of the wheel brake units and to reduce the wheel brake pressure
Implementation Method 3
an inlet valve may be opened, so that hydraulic fluid again flows into the wheel brake units and the wheel brake pressure is again restored
Data Source
AI summary
In a method for actuating a hydraulic braking system, a hydraulic fluid is temporarily stored in a storage chamber when the antilocking system is activated and recirculated back into the brake circuit with the aid of a recirculation pump. The target pump speed of the recirculation pump depends on the degree of filling of the storage chamber with hydraulic fluid and in addition on the control frequency of the antilocking system.