Linear displacement electronic feedback for hydraulic cylinders

Abstract

The purpose of this study was to research and develop a linear displacement technology that can be used to give positional feedback in hydraulic cylinders with the added ability to measure and monitor the operating temperature of the hydraulic oil. While there are solutions to this issue already in place, this study would focus upon their unique advantages and disadvantages.

The study would initially examine existing technologies comparing their advantages and disadvantages. Discussions took place with existing Burnside customers to see what their expectations were, so that their basic objectives would be met. During these meetings, the area of research was formulated with a shortlist of several potential technologies being identified. These technologies were subsequently examined in closer detail by acquisition of samples thus providing an in-depth understanding of the technological details.

The main objective was to produce a low-cost standard design sensor that had the ability to be used across multiple cylinder sizes and lengths. The study looks at integrating unique features that are not currently available in sensors, this being the incorporation of a temperature sensor.

Working on this study meant the acquisition of several new skills from the designing, constructing and testing of the electronic circuits, to the research, sourcing and purchasing of the individual components, along with learning how to manipulate and programme the Arduino Uno.

Various designs were explored in CAD to consider the best options. Individual electronic components were tested in isolation to explore limits of working conditions so the electrical signal would pass through metallic parts to work inside the hydraulic cylinders. Structural FEA analysis was performed on the pressurised and load holding sensor parts using Creo Simulate. The results correlated very well with researched results, leading to the construction and testing of the basic sub-assemblies of the sensor.

Production drawings were drafted to source machined parts, some were quite complex and involved multiple machining operations and suppliers. A short cylinder was constructed to operate by hand to test the positional sensor unit without oil and various iterations of the design took place based on findings and were retested until satisfactory results were observed. After some modifications the dry testing of the sensor was successful. The sensor design was reconfigured to operate under hydraulic pressure and elevated temperature and a new longer cylinder was designed and constructed for more intense testing of the sensor. The testing took place in Burnside Autocyl and there were various iterations of designs and retesting until satisfactory results were observed from the equipment.

The objectives of the project were achieved through the development of the measuring sensor. The sensor designed and built was low cost, would work across multiple cylinder sizes with a working temperature sensor inside and would be suitable for operation inside a hydraulic cylinder. Further investments in electronics and injection moulding parts would be required in order to get production of the sensor to operate at a commercial level. The concept was proven to work, the sensor measures position and temperature as set out in the objectives of the research. There would be further developments with the capabilities of the measuring sensor as we move into the future