Hydrostatic Traction Drive Pressure Equalization
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Solution Overview
Problem
Hydrostatic traction drives in vehicles, particularly agricultural utility vehicles, face issues with traction differences between wheels due to steering movements, leading to uneven traction levels and requiring manual driver intervention for switching between two-wheel and four-wheel drive modes.
Innovation Solution
A hydrostatic traction drive system with pivotable hydropumps and control valves that connect pressure medium flow paths between hydromotors in series, allowing for automatic pressure equalization during steering, enabling seamless switching between drive modes without operator intervention and maintaining consistent traction across all wheels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If hydromotors are connected in series to drive wheels, then synchronous running of hydromotors is guaranteed, but pressure differences occur during steering movements leading to different traction levels
Solution Approach 1:
A control valve is introduced as an intermediary component in the pressure medium flow path between series-connected hydromotors. This valve equalizes pressure differences that occur during steering movements, preventing traction level inconsistencies while maintaining the synchronous running benefit of series connection.
Solution Approach 2:
The control valve dynamically adjusts pressure medium flow parameters during steering operations. By detecting pressure differences and modifying flow distribution, the system maintains equal traction levels across all wheels despite the inherent pressure variations in series-connected hydromotor configurations during articulation.
2Adaptability or versatility
If switch valve is used to bypass downstream hydromotor for two-wheel drive, then switching between drive modes is possible, but manual driver intervention is required
Solution Approach 1:
The control valve is designed to automatically detect and respond to steering movements, enabling the system to self-adjust between two-wheel and four-wheel drive modes without driver intervention. The valve monitors pressure differences caused by steering articulation and autonomously activates the appropriate hydromotors, making the system self-regulating.
Solution Approach 2:
The system incorporates feedback through pressure sensing in the hydraulic circuit. When steering movements create pressure differences indicating a need for four-wheel drive, the control valve receives this feedback and automatically activates the downstream hydromotor, creating a closed-loop control system that responds to actual operating conditions.
3Adaptability or versatility
If articulated steering is used, then vehicle maneuverability is improved, but pressure differences between hydromotor flow paths cause traction differences
Solution Approach 1:
The control valve acts as a mediator between the articulated steering system and the series-connected hydromotors. During steering movements, the valve detects pressure imbalances caused by articulation and actively compensates by redirecting pressure medium flow, thereby maintaining equal traction levels while preserving the maneuverability benefits of articulated steering.
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 system ensures equal traction levels across all wheels during steering movements and automatic switching between two-wheel and four-wheel drive, enhancing vehicle safety and operational efficiency by compensating for pressure differences and eliminating the need for manual driver control.
Implementation Method 1
a control valve, whereby thus a pressure medium connection between the pressure medium flow paths can be controlled... pressure differences between the pressure medium flow paths between each pair of hydromotors arranged in series, in particular due to a steering movement of the wheels driven by the hydromotors, can be compensated for
Implementation Method 2
a hydropump, in particular pivotable, to drive four hydromotors
Implementation Method 3
four hydromotors. These hydromotors are connected as pairs in series
Data Source
AI summary
A hydrostatic traction drive includes a pressure medium source configured to drive four hydromotors connected as pairs in series, the pairs arranged parallel to each other. In a respective pressure medium flow path between the hydromotors of a series, a pressure medium volume flow is extracted which is diverted via a respective valve device to a pressure medium sink to bypass the respective downstream hydromotor. The hydrostatic traction drive also includes a control valve configured to balance the pressure on pressure differences between the pressure medium flow paths, in particular on a steering movement of an articulated steering. The control valve is configured to connect the pressure medium flow paths together hydraulically.