Cargo Vehicle Hydraulic Lowering Circuit for Stable Bypass Flow
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Solution Overview
Problem
Conventional hydraulic drive devices for cargo vehicles face instability in bypass oil path flow rate control due to disturbances like fluid force and foreign matter, leading to decreased energy recovery efficiency.
Innovation Solution
Incorporating a resistance element closer to the hydraulic cylinder in the lowering oil path and connecting the pilot flow path of the bypass flow rate control valve between the hydraulic cylinder and the resistance element, which increases pilot pressure by adding pressure loss, stabilizing flow rate control and improving energy recovery efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressure loss of the operation valve is increased to reduce disturbance influence, then the stability of bypass flow rate control is improved, but the energy recovery efficiency decreases
Solution Approach 1:
The invention divides the pressure loss function into two separate components: the operation valve and a dedicated resistance element. This segmentation allows the resistance element to handle the pressure loss required for stable bypass flow control, while the operation valve can operate with lower pressure loss, thereby maintaining energy recovery efficiency while achieving stable flow rate control.
Solution Approach 2:
The resistance element acts as an intermediary component between the hydraulic cylinder and the operation valve. It introduces controlled resistance to the hydraulic oil flow, generating the necessary pressure loss to stabilize the bypass flow rate control without requiring the operation valve to operate at high pressure loss, thus resolving the contradiction between stability and energy efficiency.
2Reliability
If the pilot pressure of the bypass flow rate control valve is increased to reduce disturbance influence, then the stability of flow rate control is improved, but the energy recovery efficiency decreases
Solution Approach 1:
The invention segments the pressure loss generation function from the operation valve and assigns it to a separate resistance element. This allows the resistance element to provide the necessary pressure differential for stable bypass flow control, while the operation valve maintains lower pressure loss, preserving energy recovery efficiency.
Solution Approach 2:
The resistance element serves as an intermediary that creates the required pressure difference for stable bypass flow rate control. By positioning it in the lowering oil path between the hydraulic cylinder and the operation valve, it provides the necessary pilot pressure without compromising the energy recovery efficiency of the main hydraulic circuit.
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 energy recovery efficiency and stabilizes hydraulic oil flow rate control by reducing the influence of disturbances, without increasing pressure loss at the operation valve.
Implementation Method 1
the pressure loss generated in the resistance element may be added to the pilot pressure of the bypass flow rate control valve
Implementation Method 2
a hydraulic pump that supplies and discharges hydraulic oil to and from the hydraulic cylinder for raising and lowering
Implementation Method 3
an operation valve that is disposed in the lowering oil path and that controls a flow of hydraulic oil discharged from the hydraulic cylinder
Data Source
Figure 1
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AI summary
A hydraulic drive device includes a resistance element disposed closer to the lift cylinder than the operation valve in the lowering oil path and increasing the fluid resistance. In addition, a pilot flow path of a bypass flow rate control valve is connected between the lift cylinder and the resistance element in the lowering oil path. With such a configuration, it is possible to add the pressure loss generated in the resistance element to the pilot pressure of the bypass flow rate control valve. Therefore, the pilot pressure can be increased by the addition of the pressure loss of the resistance element. By increasing the pilot pressure in this manner, it is possible to reduce the influence of the disturbance which makes the operation of the bypass flow rate control valve unstable.