Electrohydraulic Lifting Gear Relief Pressure Control
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Solution Overview
Problem
Existing solutions for controlling the relief pressure in hydraulic systems of tractors, such as those used in mowing applications, result in significant energy wastage and limited flexibility, as they either require complex and expensive components like pressure sensors and accumulators or lead to inefficient pressure medium flow, hindering the ability to adjust forces during operation.
Innovation Solution
A hoist system with an electrohydraulic lifting gear control featuring a continuously adjustable directional control valve and a proportionally adjustable relief pressure relief valve, minimizing energy losses by setting the metering orifice to a low relief volume flow, eliminating the need for pressure sensors, accumulators, or spring arrangements, and allowing for flexible pressure adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a proportionally adjustable pressure relief valve is used to regulate relief pressure, then the pressure can be adjusted flexibly for different applications, but a large volume flow of pressure medium flows out via the open metering orifice and pressure relief valve causing energy waste and heating
Solution Approach 1:
The patent applies dynamics by making the metering orifice adjustable rather than fixed. The control unit dynamically adapts the metering orifice opening degree based on the current operating state (lifting vs. relief pressure regulation), allowing the system to optimize fluid flow characteristics in real-time and minimize energy waste during relief pressure regulation.
Solution Approach 2:
The patent changes the parameter of the metering orifice opening degree based on the operating state. During relief pressure regulation, the control unit reduces the metering orifice opening to limit volume flow, thereby reducing energy waste and heating while maintaining the ability to adjust relief pressure flexibly through the pressure relief valve.
2Adaptability or versatility
If pressure relief control is implemented with existing solutions, then relief pressure can be regulated, but complex and expensive components like pressure sensors and accumulators are required
Solution Approach 1:
The patent applies self-service by enabling the lifting gear control to regulate its own relief pressure using existing components (directional control valve, pressure relief valve, and control unit). The control unit utilizes information already available from the lifting gear state to automatically adjust the metering orifice, eliminating the need for external pressure sensors, accumulators, or complex spring arrangements.
Solution Approach 2:
The patent makes the existing directional control valve and control unit multi-functional. The directional control valve not only controls lifting operations but also serves as the regulation element for relief pressure by adjusting its metering orifice. The control unit manages both lifting control and relief pressure regulation, reducing the need for dedicated separate components.
3Ease of operation
If the metering orifice is kept open for pressure relief regulation, then pressure can be controlled, but pressure medium is heated and hydraulic energy is wasted
Solution Approach 1:
The patent changes the metering orifice opening degree parameter based on the operating state. During relief pressure regulation, the control unit reduces the metering orifice opening to minimize volume flow, thereby reducing energy waste and heating while maintaining pressure control capability through the pressure relief valve.
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 efficient relief pressure regulation with minimal apparatus and energy outlay, reducing installation space and costs while maintaining effective control over pressure, allowing for flexible force adjustments and vibration damping.
Implementation Method 1
a pressure medium path from a pump (6) to a pressure chamber (14) of a lifting cylinder (10) acting in the "carrying" direction
Implementation Method 2
pressure medium flow to a pressure chamber (14) of a lifting cylinder (10)
Implementation Method 3
a proportionally adjustable relief pressure relief valve (44) in a feed line (20) between the metering orifice (26) and the pressure chamber (14) effective in the "carrying" direction, via which the pressure in the feed line (20) can be changed
Implementation Method 4
a pressure medium path from a pump (6) to a pressure chamber (14) of a lifting cylinder (10) acting in the "carrying" direction is controlled by a continuously adjustable directional control valve (26)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The unit (1) has a pressure chamber (14) of a remote cylinder (10) supplied with a pressure medium by a continuously adjustable solenoid valve (26) with an adjustable dosing diaphragm. A proportionally adjustable discharge pressure control valve (44) is provided in supply pipes (20, 36) between the dosing diaphragm and the pressure chamber. The valve (44) changes pressure in the supply pipes based on operating conditions of the lifting unit. A controller adjusts the dosing diaphragm to a discharge pressure medium flow rate during discharge pressure control. An independent claim is also included for a method for controlling a lifting unit.