Summary
A position-sensing hydraulic cylinder is a hydraulic cylinder with an integrated position feedback sensor to determine its current position.
Position-sensing hydraulic cylinders may be found in heavy industry, subsea, and mobile equipment applications.[1]
Linear Displacement Transducers edit
Internal LDT edit
With In-cylinder Linear Displacement Transducers (LDTs), the hydraulic cylinder’s piston rod must be bored through its center to accommodate certain elements of the LDT — usually the waveguide tube of a magnetostrictive transducer.[2] The machining and additional production steps associated with “gun drilling” the piston rod can add cost to the finished cylinder. Magnetostrictive LDTs provide extremely high accuracy, down to one micron.[3]
External LDT edit
External linear displacement transducers (LDTs) eliminate the need for a hollow hydraulic cylinder rod. Instead, an external sensing “bar” utilizing Hall-Effect technology senses the position of the hydraulic cylinder piston. This is accomplished by the placement of a permanent magnet within the piston.[4] The magnet propagates a magnetic field through the steel wall of the hydraulic cylinder, providing a locating signal to the sensor.
Advantages of External LDTs:
- Full rod buckling strength is maintained.
- The cylinder is easier to assemble, install, and service.
- A wide variety of sensor inputs and outputs are available.
- The external sensor is readily accessible and easy to replace; if necessary.
- If the sensing bar is replaced, re-calibration is not necessary.
- The sensing bar is small and its location along the outside of the hydraulic cylinder wall minimizes the potential for environmental damage.
- Positioning accuracy is +/- .5mm or better; more than adequate for most mobile equipment.
References edit
- ^ Herceg, Edward. "Position Sensor Technology Comparison for Hydraulic Cylinder Feedback" (PDF). Archived (PDF) from the original on 2024-04-25. Retrieved 2024-04-25.
- ^ Hydraulics & Pneumatics Magazine Archived 2011-07-18 at the Wayback Machine
- ^ Journal, Fluid Power (2019-01-10). "Strong, Tough, and Reliable: Linear Displacement Transducers Take on the Most-Demanding Applications". Fluid Power Journal. Retrieved 2024-04-25.
- ^ "Electronic Position-Sensing Hydraulic Cylinders.(Energy Manufacturing Company Inc introduces cylinders having electronic position-sensing option)(Brief article) - Design News - HighBeam Research". 2012-10-23. Archived from the original on 2012-10-23. Retrieved 2023-12-09.
External links edit
- Hydraulic Cylinders
- Hydraulic Piping Systems