Work Vehicle Hydraulic Circuit for Emergency Parking Brake Release
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Solution Overview
Problem
Existing work vehicles may fail to reliably release the parking brake in emergency situations due to the accumulation state of the hydraulic oil in the accumulator, leading to potential operational hazards.
Innovation Solution
A work vehicle design incorporating a main hydraulic pump, an auxiliary hydraulic pump, a control valve, and an emergency flow path that ensures pressure oil can be supplied to the parking brake device through a loading operation hydraulic circuit, with a valve unit that switches to communicate or shut off the emergency flow path based on pressure conditions to reliably release the parking brake.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an accumulator is used to supply hydraulic oil to the parking brake in emergency situations, then the parking brake can be forcibly released when hydraulic oil supply is interrupted, but the reliability of parking brake release depends on the accumulation state of the accumulator which may not be sufficient in critical emergencies
Solution Approach 1:
The hydraulic system is segmented into a main hydraulic pump for normal operations and a separate auxiliary hydraulic pump dedicated to emergency parking brake release. This segmentation ensures that the emergency release function has an independent oil supply source that is not dependent on the accumulator's charge state or the main pump's operational status.
Solution Approach 2:
The auxiliary hydraulic pump is designed to activate automatically when parking brake release is required in an emergency situation. The system preliminarily prepares the emergency oil supply path through the loading operation hydraulic circuit, ensuring that sufficient pressurized oil can be delivered to the parking brake device without waiting for accumulator charge accumulation.
2Reliability
If a separate auxiliary hydraulic pump and emergency flow path are added to the system, then the parking brake can be reliably released in emergencies independent of accumulator state, but the device complexity increases
Solution Approach 1:
The auxiliary hydraulic pump and its associated flow path are designed with multi-functionality. The auxiliary pump can supply hydraulic oil to the parking brake device through the emergency flow path (via the loading operation hydraulic circuit) when needed for emergency release, while also being capable of normal operation through the dedicated parking brake releasing hydraulic circuit. This universal design allows the same components to serve both emergency and routine functions, reducing the need for entirely separate dedicated emergency components.
Solution Approach 2:
The emergency flow path utilizes the loading operation hydraulic circuit infrastructure, merging the emergency release function with the existing loading hydraulic system. The auxiliary hydraulic pump integrates with the main hydraulic pump's control system, and both pumps can share common hydraulic components such as valves and fluid passages, thereby reducing overall system complexity despite the added redundancy.
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 solution ensures more reliable release of the parking brake, even in emergency situations, by providing a redundant pressure source and control mechanism, thus enhancing vehicle safety and operational reliability.
Implementation Method 1
a negative parking brake device that releases the braking state by supply of pressure oil discharged from the auxiliary hydraulic pump
Implementation Method 2
a main hydraulic pump that is driven by an engine; a lift arm cylinder that extends and retracts by a delivery pressure discharged from the main hydraulic pump
Data Source
AI summary
A work vehicle provided with a loading hydraulic circuit (A), including at least a main hydraulic pump (31), a lift aim cylinder (8) and a control valve (32), an auxiliary hydraulic pump (31), a negative parking brake device (PB), and a parking brake releasing hydraulic circuit (B2), in which the vehicle includes: a loading operation hydraulic circuit (B1) located upstream of the parking brake releasing hydraulic circuit; an emergency flow path (80) for supplying the pressure oil discharged from the auxiliary hydraulic pump to the parking brake device through the loading operation hydraulic circuit in an emergency; and a valve unit (81) located in the emergency flow path. If the pressure of the parking brake releasing hydraulic circuit is lower than the brake release pressure to release the braking state of the parking brake device, the valve unit is switched to the communicating position.