Open Hydraulic Circuit Braking With Recirculating Throttle Control
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Solution Overview
Problem
Existing open hydraulic fluid flow circuits face challenges in braking and coasting vehicles, particularly in generating braking force and avoiding cavitation, especially when operating in different directions and requiring directional movement and braking capabilities.
Innovation Solution
A fluid flow arrangement with an adjustable fluid pumping device and a fluid working machine connected via a re-circulating loop, featuring a controllable fluid throttling device and a switchable conduit, allows for variable fluid flow resistance to achieve braking and coasting while preventing cavitation, using an electronic controlling device to manage pressure and flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an open hydraulic fluid flow circuit is used for propelling a vehicle, then the device complexity is reduced and ease of manufacture is improved, but the ability to generate braking force and avoid cavitation during braking and coasting operations deteriorates
Solution Approach 1:
The patent applies dynamics by making the hydraulic circuit configuration changeable during operation. The switchable connection allows the system to transition between open circuit mode (during propulsion) and a modified configuration (during braking/coasting), enabling the circuit to adapt its structure dynamically to meet different operational requirements without permanently increasing complexity
Solution Approach 2:
The patent introduces an intermediary mechanism (the switchable connection and controllable throttling device) that mediates between the simple open circuit structure and the need for braking capability. This intermediary allows temporary modification of the circuit behavior to generate braking force while maintaining the overall simplicity of the open circuit design
2Force
If mechanical brakes are used to provide braking force in an open hydraulic circuit, then braking capability is improved, but energy efficiency deteriorates and component wear increases
Solution Approach 1:
The patent uses hydraulic principles to create a hydrodynamic brake by introducing fluid flow resistance through the controllable throttling device. This hydraulic braking mechanism replaces mechanical friction brakes, converting kinetic energy into hydraulic pressure and heat through fluid resistance, thereby eliminating mechanical wear and improving energy efficiency while maintaining braking force
Solution Approach 2:
The hydraulic system serves dual purposes: propulsion during normal operation and braking during deceleration. The same hydraulic circuit and fluid that drive the vehicle forward also provide braking force when the throttling device restricts flow, allowing the system to brake itself without separate mechanical braking components
3Force
If fluid flow resistance is increased to generate braking force, then braking capability is improved, but the risk of cavitation on the suction side of the hydraulic pump increases
Solution Approach 1:
The patent employs feedback control through the electronic controlling device that monitors system conditions and adjusts the throttling device accordingly. The controller receives information about pump operation and fluid flow conditions, then modulates the throttling to generate braking force while maintaining pressure levels that prevent cavitation, creating a self-regulating system that balances braking performance with cavitation avoidance
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 solution enables efficient, wear-free braking and coasting operations in open hydraulic fluid flow circuits, enhancing energy efficiency and reducing component wear, while allowing for bidirectional vehicle movement and precise control of braking performance.
Implementation Method 1
the controllable fluid throttling device (22, 21) is actuated so that it generates essentially no fluid flow resistance
Implementation Method 2
one is also confronted with the problem of how to avoid cavitation on the suction side of the combined hydraulic pump/hydraulic motor in these modes of operation
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a fluid flow arrangement (1, 15) with an adjustable fluid pumping device (2) and a fluid working machine (12). The fluid working machine (12) is connected to the fluid pumping device (2) and a re-circulating loop is provided for the fluid working machine (12). The re-circulating loop is fluidly connecting a first fluid port (A) and a second fluid port (B) of the fluid working machine (12), where the first (A) and the second fluid port (B) are at times at a different pressure level. The re-circulating loop comprises a controllable fluid throttling device (21, 22), and a switchable fluid conduit device (23, 24), so that a defined decelerating force can be generated for the fluid working machine (12). Reference list 1. Hydraulic propelling circuit 2. Main hydraulic pump 3. Combustion engine 4. Driving shaft 5. Auxiliary hydraulic pump 6. Fluid reservoir 7. High pressure side 8. Low pressure side 9. Low pressure relief valve 10. Fluid valve (right) 11. Fluid valve (left) 12. Fluid working machine 13. Electronic controller 14. Electric signal lines 15. Hydraulic propelling circuit (second embodiment) 16. Pressure sensor (right) 17. Pressure sensor (left) 18. Middle part 19. Valve combination (right) 20. Valve combination (left) 21. Adjustable pressure relief valve (right) 22. Adjustable pressure relief valve (left) 23. Check valve (right) 24. Check valve (left) 25. Pressure sensor (low pressure side) 26. Hydraulic fluid line 27. Arrow 28. ΔPmaximum allowable 29. Comparator 30. PA, set point 31. PA (measured) 32. Comparator 33. PPRV 34. ΔPno circulation 35. PC 36. PC+ΔPallowable