Hydraulic Armature Position Indication via Preload Pressure
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Solution Overview
Problem
The exact indication of the position of hydraulically actuated armatures over long distances is hindered by the compressibility of hydraulic fluid in pipelines, and pressure pulses from switch valve operations can disrupt the accurate counting of pulses, affecting the position indication of adjacent armatures.
Innovation Solution
Maintaining a preload pressure in the return line of each armature and using a learning cycle to account for real conditions during startup, ensuring that the indication of position is independent of end or intermediate positions, and compensating for compression volume by measuring pulses during specific positions of the piston in the cylinder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pulse counting is used to indicate armature position, then position indication is achieved, but compressibility of hydraulic liquid causes inaccurate position indication over long distances
Solution Approach 1:
The system performs a learning cycle during startup to pre-determine the relationship between pulse counts and actual armature positions. This preliminary calibration accounts for the compressibility of hydraulic liquid in long lines, enabling accurate position indication throughout subsequent operation without requiring real-time compensation for line length effects.
Solution Approach 2:
The system changes the operational parameters by maintaining different pressure levels in feed lines versus return lines. By keeping return lines at a lower, substantially constant pressure while feed lines operate at high pressure, the system compensates for hydraulic liquid compressibility effects, ensuring accurate position indication regardless of line length.
2Ease of operation
If switch valves are used to control armatures from a central control station, then centralized control is achieved, but pressure pulses during switching disrupt pulse counting and affect position indication of adjacent armatures
Solution Approach 1:
The hydraulic system is segmented into separate high-pressure feed lines and low-pressure return lines for each armature. This segmentation isolates pressure pulses generated during switching operations to individual armature circuits, preventing them from propagating to adjacent switch valves and disrupting their pulse counting. The return lines are specifically designed to maintain substantially constant low pressure despite switching activities elsewhere in the system.
Solution Approach 2:
The return line system acts as an intermediary that absorbs and dampens pressure pulses. By providing a dedicated return path that maintains substantially constant low pressure, the system mediates between the high-pressure switching operations and the sensitive pulse counting mechanism, preventing harmful pressure wave propagation while preserving centralized control capability.
3Speed
If high pressure is applied to move the piston quickly, then actuation speed is improved, but compressibility effects increase and reduce position indication accuracy
Solution Approach 1:
The hydraulic circuit is divided into separate high-pressure feed lines for rapid actuation and low-pressure return lines for accurate measurement. This segmentation allows the system to apply high pressure for fast piston movement while maintaining a separate low-pressure reference environment that minimizes compressibility effects on position indication accuracy.
Solution Approach 2:
The system changes pressure parameters by maintaining a substantial pressure difference between feed lines (high pressure for speed) and return lines (low pressure for measurement accuracy). This parameter separation enables simultaneous achievement of rapid actuation and accurate position indication by ensuring that compressibility effects are minimized in the measurement reference environment.
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 solution effectively dampens pressure pulses and compensates for hydraulic fluid compressibility, providing a more accurate and reliable indication of armature position over time and after multiple switching procedures, even in complex systems with multiple interconnected switch valves.
Implementation Method 1
the flow of the hydraulic liquid flowing through one of the hydraulic lines is converted into a number of electric pulses, each of which corresponds to a pre-determined unit of volume of the hydraulic liquid
Implementation Method 2
pressure pulses which result through switching procedures at one switch valve, or at a plurality of switch valves, are compensated and damped by the preload pressure in the return line connected to the armature
Implementation Method 3
the compressibility of the hydraulic liquid in the lines corresponds partly to the displacement volume of the armature. Therefore, an exact indication of the position of the armature concerned is not possible without compensation of the compressibility of the hydraulic liquid in the pipeline system
Data Source
AI summary
The invention relates to a method for indicating the position of a hydraulically actuated armature, having a piston (1.21) in a cylinder (1.2) for actuating the armature (1.1), which cylinder is connected by means of two hydraulic lines (2, 3) to a switch valve (7) through which the hydraulic lines can be switched between pressure-conducting feed flow and pressureless return flow, wherein the flow of the hydraulic fluid flowing through one of the hydraulic lines is converted into a number of electric pulses, each of which corresponds to a pre-determined unit of volume of the hydraulic fluid, the switch valve (7) is connected to supply lines (P, T), to which further switch valves (7) are connected for actuating further armatures (1.n), the switch valves (7) are connected via a branch line (T1) to the return line (T) common to all armatures, and wherein at each switch valve (7) in the branch line (T1) to the return line (T), a preload pressure is maintained which is higher than the pressure in the common return line (T).Furthermore, a program is provided which processes the pulses of the throughflow sensor and carries out a learning cycle.