Hydraulic Actuator Flow Control Using Sampling-Line Temperature Sensing
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Solution Overview
Problem
In work machines like hydraulic excavators, temperature variations in hydraulic operating fluids lead to deviations in temperature measurement, affecting valve control characteristics and reducing flow rate control performance, which compromises actuator control accuracy.
Innovation Solution
A temperature sensor is placed on a sampling hydraulic line that branches from the main hydraulic line, allowing for direct measurement of the hydraulic fluid temperature and correction of the command electrical signal to maintain accurate flow rate control irrespective of temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the temperature sensor is disposed in the valve housing, then the valve temperature can be sensed, but a large deviation is caused between the measured temperature and the hydraulic operating fluid temperature
Solution Approach 1:
A sampling hydraulic line is introduced as an intermediary to transport hydraulic operating fluid from the main hydraulic line to the temperature sensor mounting location. This allows the temperature sensor to measure the actual fluid temperature without being directly exposed to high-pressure hydraulic lines, while still obtaining accurate temperature data for control corrections.
Solution Approach 2:
The temperature measurement function is extracted from the main hydraulic line by creating a separate sampling hydraulic line. This separates the temperature sensing function from the high-pressure fluid transmission function, allowing the temperature sensor to be positioned in a safe location while still measuring the actual fluid temperature.
2Measurement precision
If the temperature sensor is placed on the sampling hydraulic line, then the hydraulic operating fluid temperature can be accurately measured, but the device complexity increases
Solution Approach 1:
The hydraulic system is segmented into the main hydraulic line for power transmission and a separate sampling hydraulic line for temperature measurement. This segmentation allows each line to be optimized for its specific function while maintaining overall system integration through the controller.
Solution Approach 2:
The sampling hydraulic line serves multiple functions: it provides temperature measurement data, acts as a thermal coupling between the hydraulic fluid and sensor, and enables control corrections without interfering with the main hydraulic power transmission function.
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 configuration ensures consistent actuator control accuracy by accurately measuring and adjusting for temperature variations in the hydraulic fluid, enhancing the robustness of flow rate control performance across varying temperatures.
Implementation Method 1
a temperature sensor set on the sampling hydraulic line
Data Source
AI summary
A work machine that can keep the control accuracy of actuators irrespective of temperature variation of a hydraulic operating fluid that passes through flow rate controllers that control the flow rates of supply to the actuators is provided. For this purpose, the flow rate controllers each have a valve body that is disposed on a main hydraulic line connecting a delivery line of a hydraulic pump and the actuator and that moves according to an operation pressure from a solenoid proportional pressure reducing valve, a sampling hydraulic line that branches from the main hydraulic line, and a temperature sensor set on the sampling hydraulic line. The controller is configured to correct a command electrical signal to the solenoid proportional pressure reducing valve according to a signal from the temperature sensor.