Hydrostatic Assembly Control Using Temperature-Based Viscosity Estimation
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Solution Overview
Problem
Existing hydrostatic systems face high costs and inefficiencies due to the need for specialized viscosity sensors to account for temperature and pressure variations in the viscosity of pressure media, which affects power transfer and lubrication.
Innovation Solution
A hydrostatic assembly with a control device that determines viscosity based on temperature and pressure measurements, using stored characteristic curves or value pairs, allowing for open-loop or closed-loop control without the need for costly viscosity sensors, and includes a temperature sensing device to automatically adapt control parameters to changing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If viscosity sensors are used to determine viscosity for control purposes, then control precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent creates a model-based copy of viscosity behavior through characteristic curves stored in the control device. Instead of directly measuring viscosity with expensive sensors, the system uses temperature measurements combined with pre-stored viscosity-temperature characteristic curves to determine viscosity values. This copying approach replaces direct viscosity sensing with an indirect but accurate model-based determination method.
Solution Approach 2:
The patent substitutes the mechanical/physical viscosity sensing system with a computational model-based system. Rather than using physical viscosity sensors that directly interact with the pressure medium, the system uses temperature sensing combined with stored characteristic data and computational processing to determine viscosity. This substitution eliminates the need for complex viscosity-specific sensors while maintaining measurement accuracy.
2Measurement precision
If viscosity sensors are used to account for temperature and pressure variations, then control accuracy is improved, but equipment cost increases
Solution Approach 1:
The patent creates a model-based copy of viscosity behavior through characteristic curves stored in the control device. Instead of directly measuring viscosity with expensive sensors, the system uses temperature measurements combined with pre-stored viscosity-temperature characteristic curves to determine viscosity values. This copying approach replaces direct viscosity sensing with an indirect but accurate model-based determination method.
Solution Approach 2:
The control device performs multiple functions: it stores characteristic curves, processes temperature measurements, determines viscosity values, and adjusts control parameters based on viscosity changes. This multi-functional approach consolidates what would otherwise require separate specialized sensors and processing systems into a single control unit, reducing overall equipment cost and complexity.
3Adaptability or versatility
If the system is warmed up with expert knowledge to adapt to viscosity changes, then control adaptability is improved, but time and energy consumption increase
Solution Approach 1:
The system continuously monitors temperature through the temperature sensing device and uses this feedback to dynamically determine viscosity values from the stored characteristic curves. The control device then adjusts control parameters based on the determined viscosity, creating a closed-loop feedback system that automatically adapts to changing viscosity conditions without requiring manual warm-up procedures or expert intervention.
Solution Approach 2:
The system performs automatic viscosity-based control adaptation without requiring external expert knowledge or manual warm-up procedures. The control device autonomously determines viscosity from temperature measurements and characteristic curves, then self-adjusts control parameters to optimize performance. This self-service capability eliminates time-consuming manual adaptation processes.
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 approach reduces equipment costs and improves system dynamics by enabling efficient, automatic adaptation to viscosity changes, leading to shorter machine cycles and energy savings.
Implementation Method 1
the assembly has at least one temperature sensing device by means of which a temperature of the pressure medium can be sensed
Implementation Method 2
the viscosity is stored in the control device as a function of the temperature, for example as a table, characteristic curve, characteristic diagram or functionally, and the viscosity can be determined therefrom by means of the control device as a function of at least the sensed temperature
Data Source
AI summary
A hydrostatic assembly includes a pressure medium with a variable viscosity and a control device through which at least one process variable or state variable of the hydrostatic assembly is open-loop or closed-loop controlled as a function of the viscosity. The hydrostatic assembly further includes a temperature sensing device configured to sense a temperature of the pressure medium.