Hydraulic Load-Holding Control for Smooth Valve Reopening
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hydraulic arrangements for load holding in servo-hydraulic axles require complex position detection and pressure adjustments, leading to potential discontinuities in force or position when switching modes.
Innovation Solution
A hydraulic arrangement with a shutoff valve in the pressure medium flow path, where the operating variable of the electric motor is detected and adjusted before opening the shutoff valve, allowing for smooth pressure adjustments and reduced energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a load-holding valve is used to shut off the pressure medium flow path for holding load, then the servo motor can be switched without torque and power consumption is reduced, but unintended movement of the axle may occur when the load-holding valve opens if the pressure is not matched
Solution Approach 1:
The control unit determines a preliminary control signal for the servo motor before opening the load-holding valve. This control signal is used to adjust the pump pressure to match the load pressure before the valve opens, preventing unintended movement. The preliminary action ensures pressure matching occurs in advance, eliminating the risk of position instability when the valve transitions.
Solution Approach 2:
The system prepares for the potential harmful effect of pressure mismatch by establishing a cushioning mechanism. The control unit monitors the actual position and prepares a control signal that will compensate for pressure differences before the load-holding valve opens, cushioning against the potential shock or unintended movement that would otherwise occur.
2Reliability
If the pump pressure is brought up to load pressure before opening the load-holding valve, then unintended movement is prevented, but the servo motor must be controlled in a complex manner with time constants and tolerance bands
Solution Approach 1:
The control unit automatically determines and adjusts the control signal for the servo motor based on the actual position of the axle and the state of the load-holding valve. The system serves itself by autonomously managing the pressure matching process without requiring complex external control logic, time constants, or tolerance band calculations, thereby reducing control complexity while maintaining reliability.
3Reliability
If position detection and complex pressure adjustments are implemented, then smooth switching between modes is achieved, but additional sensors and complex control systems are required
Solution Approach 1:
The control unit performs multiple functions: it monitors the actual position of the axle, determines the control signal for the servo motor, manages the load-holding valve, and ensures pressure matching. By consolidating these functions into a single control unit, the system achieves smooth switching between load-holding and active control modes without requiring additional dedicated sensors or complex separate control systems.
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 enables smooth switching from load-holding to active control modes without discontinuities in force or position, reducing energy consumption and eliminating the need for additional sensors.
Implementation Method 1
a hydraulic pump (4) for supplying a pressure medium
Implementation Method 2
hydraulic arrangement (1) having a hydraulic cylinder (6, 8, 10) and a hydraulic pump (4) for supplying a pressure medium
Implementation Method 3
at least one shutoff valve (20, 22, 32) arranged in the pressure medium flow path (12, 14, 18), via which the pressure medium flow path (12, 14, 18) can be hydraulically disconnected
Data Source
AI summary
A hydraulic arrangement includes a hydraulic cylinder and a hydraulic pump for its pressure medium supply, which can be driven by an electric motor of the arrangement and can be fluidically connected to a cylinder chamber via a pressure medium flow path. At least one shutoff valve is provided in the pressure medium flow path, through which the pressure medium flow path can be hydraulically disconnected for load holding of the hydraulic cylinder without drive. An operating variable of the electric motor is determined or detected upon hydraulic disconnection of the pressure medium flow path, and the detected or determined operating variable is set and tracked on the electric motor upon setting a condition at which the pressure medium flow path is opened.