Hydraulic Load-Holding Assembly for Smooth Valve Reopening
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Solution Overview
Problem
Existing hydraulic arrangements face challenges in smoothly switching from load-holding mode to resuming load control, often requiring complex pressure equalization and position detection, which can lead to unwanted movements and increased complexity.
Innovation Solution
A hydraulic arrangement with a control unit that adjusts the operating variable of an electric motor driving the hydraulic pump, allowing for simple pressure adjustment and smooth switching between load-holding and load-resumption modes without significant pressure changes or movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If a load-holding valve is used to block the pressure medium flow path, then the servo motor can be switched to torque-free operation reducing power consumption and wear, but unwanted movement of the axis may occur when the load holding valve opens if the pressure between the pump and the load holding valve is not adapted to the load
Solution Approach 1:
The control unit determines the operating variable (torque) of the electric motor before opening the load-holding valve and uses this information to pre-adjust the pump pressure to match the load pressure. This preliminary pressure adaptation prevents unwanted axis movement when the valve opens, while still allowing the servo motor to operate in torque-free mode during load holding.
Solution Approach 2:
The control unit uses feedback from the electric motor's operating variable (torque) during the hydraulic separation to intelligently control the pump pressure. This feedback mechanism ensures the pump pressure is adapted to the actual load conditions, preventing position instability when transitioning between load-holding and load-resumption modes.
2Reliability
If position detection and complex servo motor control are used to equalize pressure levels before opening the load-holding valve, then unwanted movements can be prevented, but the control system complexity increases
Solution Approach 1:
The invention extracts and utilizes the electric motor's torque information as a simple, readily available indicator of load conditions. Instead of requiring complex position detection systems and multi-stage pressure equalization control, the solution uses the motor's operating variable directly to control pump pressure, significantly simplifying the control system while maintaining reliability.
Solution Approach 2:
The control system uses information already available from the electric motor (its operating variable) to automatically adjust pump pressure. The system serves itself by utilizing existing sensor data without requiring additional position sensors or complex control algorithms, reducing overall system complexity while maintaining position stability.
3Reliability
If the pump remains fluidly connected to the axis for load holding, then position control can be maintained, but internal leakage of the pump causes continuous power consumption
Solution Approach 1:
The system segments the hydraulic circuit by introducing a load-holding valve that can hydraulically separate the pressure medium flow path between the pump and the cylinder. This allows the pump to be disconnected during load holding, eliminating continuous power consumption from internal leakage, while position control capability is restored when the valve opens and the pump reconnects to the 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
The solution enables controlled and energy-efficient switching between load-holding and load-resumption modes, reducing the need for position and pressure sensors, simplifying control systems, and preventing unwanted movements.
Implementation Method 1
a check valve (32) is provided in the pressure medium flow path (14) by means of which the pressure medium flow path (14) can be hydraulically isolated to hold a load (10) of the hydraulic cylinder (6, 8, 10) without drive
Implementation Method 2
a hydraulic pump (4) for supplying the latter with pressure medium, which hydraulic pump (4) is drivable by an electric motor (2)
Implementation Method 3
hydraulic pump (4) for supplying the latter with pressure medium
Data Source
Figure 1
Figure 2~3
AI summary
A hydraulic arrangement (1) is disclosed, comprising a hydraulic cylinder (6, 8, 10) and a hydraulic pump (4) for its hydraulic fluid supply. The hydraulic pump (4) can be driven by an electric motor (2) of the arrangement (1) and can be fluidically connected to a cylinder chamber via a hydraulic fluid flow path (12, 14, 18). At least one shut-off valve (22, 32) is provided in the hydraulic fluid flow path (12, 14, 18), through which the hydraulic fluid flow path (12, 14, 18) can be hydraulically disconnected to hold a load on the hydraulic cylinder (6, 8, 10) without drive force. An operating parameter of the electric motor (2) is determined or recorded during the hydraulic separation of the pressure medium flow path (12, 14, 18) and the recorded or determined operating parameter is set and adjusted on the electric motor (2) when a condition is set under which the pressure medium flow path (12, 14, 18) is opened.