Hydraulic Brake Priority Flow Control Valve
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Solution Overview
Problem
Current hydraulic brake systems for construction vehicles face limitations, such as volume constraints in master cylinder designs, complexity in priority flow control schemes, and reliance on charge pressure, which can result in reduced braking capability when charge pressure is low.
Innovation Solution
A hydraulic brake system incorporating a priority flow control valve that directs operating pressure to both controlled and excess flow ports, connecting these to steering and service brake units, ensuring priority flow for braking and steering, and utilizing an accumulator to maintain pressure in case of pump failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a master cylinder design is used to supply the service brake, then the system structure is simplified, but the volume limitation reduces braking capability
Solution Approach 1:
The brake system is segmented into a service brake circuit and a parking brake circuit, each with dedicated pressure sources. The service brake uses a high-pressure accumulator while the parking brake uses the charge system, allowing each circuit to be optimized independently for its specific function without volume limitations affecting the other.
Solution Approach 2:
A high-pressure accumulator is introduced as an intermediary pressure source for the service brake circuit. This accumulator stores hydraulic fluid under high pressure and supplies it to the service brake, eliminating the volume limitations of master cylinder designs while maintaining system structural simplicity.
2Quantity of substance
If a priority flow control scheme is used to supply the service brake, then braking capability is improved, but the system complexity increases due to additional control valves and plumbing
Solution Approach 1:
The high-pressure accumulator is pre-charged to a pressure higher than the maximum steering pressure during system operation. This preliminary action ensures that when the service brake is actuated, high pressure is immediately available without requiring complex priority flow control valves or additional plumbing to redirect charge pressure.
3Device complexity
If charge pressure is used to supply the service brake, then the system structure is simplified, but the braking capability is limited when charge pressure is low
Solution Approach 1:
The accumulator is pre-charged to a high pressure during system operation before braking is needed. This preliminary charging ensures that when the service brake is actuated, high pressure is immediately available from the accumulator regardless of the current charge system pressure, eliminating the limitation of low charge pressure on braking capability.
Solution Approach 2:
The high-pressure accumulator serves as an intermediary pressure source that decouples the service brake pressure from the charge system pressure. The accumulator maintains a reservoir of high-pressure fluid that can be supplied to the service brake independently of the charge system's current pressure state.
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 configuration enhances braking capability by providing consistent high pressure to the service brake, simplifies system complexity, and ensures reliable braking performance even when charge pressure is low, by utilizing an accumulator to store energy for the service brake system.
Implementation Method 1
utilizing an accumulator to maintain pressure in case of pump failure
Data Source
AI summary
Embodiments of a hydraulic brake system are disclosed. In one embodiment, a priority flow control valve for supplying operating pressure has a first orientation in which operating pressure is provided at a controlled flow port and a second orientation in which operating pressure is provided at the controlled flow port and an excess flow port. A steering control unit has an inlet port for receiving operating pressure and an outlet port for communicating a steering control load sense signal. A brake control unit has an inlet port for receiving operating pressure and an outlet port for communicating a braking control load sense signal. The inlet port of the brake control unit and the inlet port of the steering control unit are connected to the controlled flow port.