Position Sensing SMART Cylinders: The Ultimate in Automation
Hydraulic and Pneumatic cylinders have become high tech. By incorporating position sensing (SMART) technology, mobile hydraulic and industrial applications are seeing major benefits in operations where productivity is everything.
The technology has been around for decades, but after years of field experience and refinement, SMART cylinders have proven to be extremely reliable, even in harsh environments and high temperatures. Increased efficiency, improved safety and unprecedented levels of performance all contribute to a rising popularity among equipment manufacturers.
SMART cylinders, also referred to as electro-hydraulic control, intelligent cylinders, and electronic position sensing cylinders, are specifically designed for direct stroke measurement. By integrating a linear sensor into a cylinder, electronic feedback is provided indicating its stroke position and velocity. This data is used in many ways to increase equipment productivity and safety while reducing maintenance and downtime.
Smart Cylinder Applications
The list of equipment automation is growing for industries such as oil and gas, transportation, construction, agriculture and more. Here are a few examples of automation:
- Advanced suspension systems to reduce vibration and improve operator comfort
- Automatic steering controlled by GPS to ensure straight travel and ideal overlap
- Cultivator depth control capable of handling a rugged environment
- Auto-levelling tools and return to position features
What are the Benefits of a Smart Cylinder?
Dynamic self-adjusting – A system can feed multiple inputs into a control mechanism and have that sensor react according to those inputs. For example: pressure, speed and velocity can be programmed to dynamically enable cylinder cushioning
Remote adjustability – One of the greatest benefits of a position sensing cylinder is the remote adjustability. Settings can be adjusted and fine-tuned on the fly remotely using a smart phone 1,000 miles away
Repeatability – Recurring operations can be programmed with high precision accuracy and repeatability to the sub-millimeter resulting in less operator fatigue
Lockout / Safety– A system can be programmed to lockout a particular function. Examples include capping equipment speed or preventing equipment mobility when outriggers are still extended
How Does a Smart Cylinder Work?
A “SMART” cylinder is a type of hydraulic or pneumatic actuator that incorporates a linear transducer (sensor) that can be mounted either internally or externally.
The sensor provides instantaneous feedback of position and velocity and can be outputted to various analog and digital formats. Through electro-hydraulic control, equipment function can be automated to improve overall performance and efficiency.
Accuracy as high as +/- 0.004” (+/- 0.1mm) can be achieved, depending on cylinder stroke length and other design parameters.
Smart Cylinder Design
A cylinder featuring an internal LDT is common, especially in new cylinder manufacturing.
In this design, the solid piston rod is gun drilled (bored through its center) at a small diameter to accommodate the waveguide tube of a magnetostrictive transducer. The cylinder piston is counterbored to encase a permanent magnet and the endcap typically houses the convertor assembly.
The greatest advantage of this design is that the sensor assembly is housed completely inside the cylinder and there is no better protection from the elements or physical impact than the steel cylinder barrel itself.
An internal LDT can also be added to an existing cylinder so long as there is ample endcap room for the convertor.
External Linear Displacement Transducers (LDTs)
The externally mounted option features an externally mounted sensor utilizing the Hall-Effect to sense the position of the cylinder’s piston. The magnet propagates a magnetic field through the carbon steel wall of the cylinder, providing a locating signal to the sensor.
The advantage to this design is the externally mounted sensor is easily accessible for maintenance or service. An externally mounted sensor can also be easily applied to an existing cylinder.
Is a SMART Cylinder right for me?
Incorporating a position sensor into either a cylinder is straight forward and not as expensive as you might think. An experienced cylinder manufacturer will be able to help you develop such a design and determine if a SMART cylinder is suitable for your project.
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