Hydraulic Pump Relief Switching for Multi-Cylinder Pressure Limits
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional hydraulic drive devices for industrial vehicles cannot adjust the upper limit pressure of hydraulic oil discharged from the hydraulic pump based on the operated hydraulic cylinder, leading to inefficient operation and potential overload.
Innovation Solution
A hydraulic drive device with a capacity control valve that adjusts the swash plate angle of the hydraulic pump, combined with an electromagnetic proportional valve and relief valve system, to set different relief pressures based on the operation of specific hydraulic cylinders, allowing the upper limit pressure to change accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional hydraulic drive device uses a fixed upper limit pressure setting, then the pressure control is simple and reliable, but the system cannot adapt to different hydraulic cylinders and operates inefficiently
Solution Approach 1:
The patent implements dynamic pressure control by switching between different relief valves (first relief valve for first hydraulic cylinder, second relief valve for second hydraulic cylinder) based on which cylinder is operating. This allows the upper limit pressure to be dynamically adjusted according to the specific hydraulic cylinder in use, resolving the contradiction between adaptability and system complexity.
Solution Approach 2:
The system changes the pressure parameter by selecting different relief valves with different set pressures. When the first hydraulic cylinder operates, the first relief valve sets a specific upper limit pressure; when the second hydraulic cylinder operates, the second relief valve sets a different upper limit pressure. This parameter switching mechanism enables adaptability without requiring a completely complex control system.
2Reliability
If the hydraulic pump operates at constant upper limit pressure, then the pump control is simple, but the system may cause overload on certain hydraulic cylinders
Solution Approach 1:
The patent segments the pressure control function by providing separate relief valves for different hydraulic cylinders. The first relief valve protects the first hydraulic cylinder with its specific upper limit pressure setting, while the second relief valve protects the second hydraulic cylinder with its own setting. This segmentation allows targeted protection for each cylinder, improving reliability without requiring a single complex over-comprehensive control system.
Solution Approach 2:
The relief valves act as intermediary devices between the hydraulic pump and the respective hydraulic cylinders. They mediate the pressure control by automatically limiting the pressure to predetermined upper limits specific to each cylinder's load requirements. This intermediary mechanism provides reliable overload protection while keeping the overall system design relatively simple.
3Adaptability or versatility
If the system uses multiple relief valves with different pressure settings, then the upper limit pressure can be adjusted for different cylinders, but the device complexity increases
Solution Approach 1:
The hydraulic pump serves multiple functions by being able to supply hydraulic oil to different hydraulic cylinders with different pressure requirements. The system achieves universality through the multi-cylinder configuration with switched relief valves, allowing one pump to serve multiple purposes with different pressure settings, thereby justifying the added component complexity through enhanced versatility.
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
Enables the hydraulic drive device to adjust the upper limit pressure of hydraulic oil discharge in real-time according to the operated hydraulic cylinder, optimizing operation and protecting components by preventing overpressure.
Implementation Method 1
a hydraulic pump 4 that is of a variable capacity type, discharging hydraulic oil stored in the tank 3
Implementation Method 2
a relief valve 37 that limits an upper limit pressure of hydraulic oil discharged from the hydraulic pump 4
Implementation Method 3
an electromagnetic proportional valve 41...moves the valve body 47 in accordance with a degree of opening of the electromagnetic proportional valve 41
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A hydraulic drive device (1) for an industrial vehicle (2) includes a tank (3), a hydraulic pump (4), a capacity control valve (5), a plurality of hydraulic cylinders (6, 8, 9), a plurality of direction switching valves (7,27, 31), a first hydraulic oil passage (12, 29, 33), a second hydraulic oil passages (16, 17, 18), a pilot line (19, 30, 34A, 34B), a relief valve (40), a relief pressure setting portion (40a, 41, 42), a plurality of operation detecting portions (51, 52),and a control unit (53). The control valve (5) controls the hydraulic pumps (4) so that a differential pressure between a discharge pressure of the hydraulic pump (4) and a pilot pressure of the pilot line (19) is to be a predetermined pressure. The control unit (53) controls the relief pressure setting portion (40a, 41, 42).