Hydraulic Unit Prefilling Location for Brake System
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Solution Overview
Problem
Existing hydraulic units for motor vehicle brake systems face challenges in ensuring bubble-free filling and air exclusion in secondary circuits, requiring complex venting and filling measures, especially when prefilled by manufacturers.
Innovation Solution
Incorporating a prefilling location in the pump suction conduit between the pressure-retaining valve and the change-over valve allows for initial evacuation and prefilling of the secondary circuit by the brake manufacturer, simplifying the process and reducing complexity and costs, while allowing the vehicle producer to focus on filling the primary circuit with brake fluid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire brake system including secondary circuits is prefilled with brake fluid, then the operational readiness is improved, but the complexity of the filling process and risk of air inclusions increases
Solution Approach 1:
The brake system is divided into primary circuit and secondary circuit, with the secondary circuit further segmented into pump suction conduit and wheel brake circuits. The filling process is correspondingly segmented: the brake manufacturer prefills only the primary circuit and pump suction conduit up to the pressure-retaining valve, while the vehicle producer completes the filling of wheel brake circuits later, reducing initial complexity while ensuring operational readiness.
Solution Approach 2:
The brake manufacturer performs preliminary filling of the primary circuit and pump suction conduit with brake fluid before delivery, preparing the system in advance. This preliminary action ensures that critical components are ready, while leaving the secondary wheel brake circuits to be filled later by the vehicle producer, balancing operational readiness with process simplicity.
2Reliability
If complex venting and filling measures are implemented for secondary circuits, then air exclusion is improved, but the time and cost of manufacturing increases
Solution Approach 1:
The pressure-retaining valve is extracted as a separate functional component that hydraulically separates the primary circuit from the secondary wheel brake circuits. This extraction allows the brake manufacturer to complete filling and air exclusion for the primary circuit without needing to vent the secondary circuits, eliminating complex venting measures and reducing manufacturing time.
Solution Approach 2:
The pressure-retaining valve acts as an intermediary element that allows the primary circuit to be filled and vented independently from the secondary circuits. This intermediary component enables the brake manufacturer to complete air exclusion in the primary circuit without requiring complex venting measures for the entire brake system, reducing both time and cost.
3Ease of operation
If the pump suction conduit is prefilled by the brake manufacturer, then the vehicle producer's work is simplified, but the risk of air inclusions in the secondary circuit increases
Solution Approach 1:
The pressure-retaining valve is positioned to allow the pump suction conduit to be filled by the brake manufacturer, converting what could be a source of air inclusions (prefilling the secondary circuit) into a benefit. The valve's hydraulic separation ensures that any air inclusions remaining in the pump suction conduit do not affect the wheel brake circuits, as the valve prevents hydraulic communication between the circuits.
Data Source
AI summary
A hydraulic unit for a motor vehicle brake system operating on the recirculation principle, in which each brake circuit has in the region of the hydraulic unit a prefilling location which opens into the pump suction conduit between the pressure-retaining valve and the change-over valve for the purpose of receiving brake fluid. The hydraulic unit can thereby be prefilled with lower complexity and cost in terms of time and processes prior to installation in the vehicle.