Electrohydraulic Braking Pressure Limiting Valve
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Solution Overview
Problem
The existing electrohydraulic power vehicle braking systems face issues with excessive hydraulic pressure buildup due to dynamic effects, which can damage the system, and existing solutions like solenoid valves are insufficient in preventing pressure exceedance.
Innovation Solution
A mechanical pressure limiting valve is integrated into the system, set to the permissible maximum pressure, which connects the power brake pressure generator to the brake fluid reservoir to prevent excessive pressure spikes, and a single piston seal is used for sealing, reducing the risk of damage and allowing for efficient brake fluid management during slip control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the power brake pressure generator rapidly builds up brake pressure to the permissible maximum pressure, then the brake pressure buildup speed is improved, but the pressure may exceed the permissible maximum pressure by 50% or more due to dynamic effects
Solution Approach 1:
The pressure limiting valve is pre-configured with a setpoint corresponding to the permissible maximum pressure of the vehicle braking system. This preliminary setup ensures that when rapid pressure buildup occurs, the valve automatically activates at the correct pressure threshold to prevent exceedance, without requiring real-time control decisions or complex feedback mechanisms.
2Speed
If the power brake pressure generator is shut down upon reaching the permissible maximum pressure, then the pressure control response time is improved, but the pressure still exceeds the permissible maximum pressure due to dynamic effects
Solution Approach 1:
The pressure limiting valve acts as an intermediary component between the power brake pressure generator and the hydraulic wheel brakes. It provides a passive mechanical means of pressure limitation that operates independently of the generator's shutdown response, thereby mediating the pressure control function to prevent exceedance regardless of the generator's response time.
3Reliability
If multiple piston seals are used in the piston-cylinder unit, then the sealing reliability is improved, but the device complexity and risk of installation hazards increase
Solution Approach 1:
The pressure limiting valve provides system-level pressure protection that eliminates the need for multiple piston seals to manage pressure-related sealing risks. By handling pressure limitation at the system level rather than requiring redundant sealing components at the piston level, the system achieves adequate sealing reliability with fewer components, reducing installation complexity and potential hazards.
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 mechanical pressure limiting valve effectively prevents excessive pressure spikes, ensuring the system operates within safe limits, reducing the risk of damage and allowing for efficient brake fluid management, while also simplifying the design and reducing the risk of installation hazards.
Implementation Method 1
A pressure limiting valve limits a pressure in the power brake pressure generator
Implementation Method 2
The piston seal surrounds the piston and forms a seal at a circumference between the piston and the cylinder
Data Source
AI summary
A connection of a piston-cylinder unit of an power brake pressure generator of an electrohydraulic power vehicle braking system to an unpressurized brake fluid reservoir with the aid of a pressure limiting valve and a controllable valve. The pressure limiting valve prevents pressure spikes in the vehicle braking system if inlet valves of hydraulic wheel brakes of the vehicle braking system are closed during a pressure buildup with the aid of the power brake pressure generator. Brake fluid may be drawn in or discharged from the brake fluid reservoir via the controllable valve during a slip control.