Parking Brake Piston Locking via Parallel Hydraulic Valves
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Solution Overview
Problem
Existing parking brake systems for motor vehicles with automatic transmissions lack operational reliability, particularly in ensuring the brake piston remains fixed in locking or releasing positions due to potential faulty actuation.
Innovation Solution
A parking brake system with a single-acting hydraulic brake cylinder, a piston spring for a failsafe braking position, and a piston lock that can be actuated by a locking valve connected to a fluid-conducting system, allowing for autonomous operation of valves and increased reliability through parallel valve connectors and control pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the brake piston is fixed in position by a locking apparatus, then the parking brake system achieves reliable position holding, but the system complexity increases due to additional locking mechanisms and fluid-conducting connections
Solution Approach 1:
The piston lock is integrated within the brake cylinder assembly, with the locking valve and piston lock forming a nested hierarchical structure where the piston lock is contained within the brake cylinder and the locking valve controls the piston lock through fluid connections. This nesting reduces overall system complexity while maintaining reliability.
Solution Approach 2:
The locking valve acts as an intermediary component between the hydraulic control system and the piston lock mechanism. It mediates the control function by receiving control signals and translating them into hydraulic pressure changes that actuate the piston lock, thereby simplifying the overall control architecture while ensuring reliable operation.
2Reliability
If the locking valve is connected directly to the supply pressure system, then the valve can be actuated autonomously improving reliability, but the fluid-conducting system complexity increases
Solution Approach 1:
The fluid-conducting system is segmented into distinct functional circuits: the main brake cylinder circuit and the piston lock circuit. The locking valve has separate fluid connections that allow it to be actuated autonomously from the supply pressure system without interfering with the main brake circuit, enabling independent operation while maintaining system reliability.
Solution Approach 2:
The locking valve is designed with dynamic fluid control capabilities, allowing it to switch between different fluid pathways based on operational requirements. The valve can connect the supply pressure system directly to the piston lock when actuation is needed, and isolate them when not needed, providing dynamic control that improves reliability while managing fluid system complexity.
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 system enhances operational reliability by ensuring the brake piston remains securely locked or released, preventing unintended movement and improving the overall functionality of the parking brake system.
Implementation Method 1
a piston spring (28) which is set up to move the brake piston (26) in one direction
Implementation Method 2
The locking valve (4) is set up to actuate the piston lock (22) by way of a hydraulic fluid
Implementation Method 3
Said piston lock can preferably be connected in a fluid-conducting manner to a locking valve (4)
Data Source
AI summary
A parking brake system for a motor vehicle transmission is provided. The parking, brake system includes a brake cylinder having a brake piston movable between braking and locking positions, a piston lock provided to lock the brake piston in the locking position, a piston valve configured to activate the brake cylinder using a fluid, and a locking valve configured to activate the piston lock using a fluid. The piston valve can be connected, in a fluid-conducting manner on the downstream side facing away from the brake cylinder, to a supply pressure system, and the locking valve, on the side facing away from and downstream of the piston lock, can be connected in a fluid-conducting manner to the supply pressure system, such that the locking valve is arranged downstream of and parallel to the piston valve relative to the supply pressure system.