position and pressure measurement in agriculture sprayers
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Gefran Inc. 8 Low ell Ave Winchester, MA 1-888-888-4474 w w w .gefran.com North America 01890 [email protected]
GEFRAN SOLUTIONS FOR AGRICULTURAL SPRAYER APPLICATIONS
A sprayer is a simple machine basically consisting of a tank, a pump and nozzles. The tank can hold hundreds gallons of water and chemical, the pump sucks from the tank, discharges through filters and pressure controls to the booms where the pressure is converted to velocity in jets, causing atomization. To increase accuracy and efficiency, controls systems have been developed to assist the operator. As the working width has increased, booms weight increased too, requiring hydraulic actuators and levelling systems to reach and maintain the correct working height. Fluid flow rate and fluid pressure are controlled with high accuracy in order to be sure enough chemicals are sprayed and, at the same time, they are not wasted. Advanced controllers are used to read tractor position and speed. Some modern sprayers are self-propelled and are controlled by an autopilot. They need an accurate steering angle measurement to give a feedback to the GPS system that, through the autopilot unit, tracks the sprayer’s movements.
Hydraulic levelling system as well as steering control systems require a sensor to read the cylinder’s position. Sensors can be installed inside or outside the cylinder, depending on the level of integration and maintenance expected on the machine. Resistive LDTs with ball-joints are the most common and cost effective solution. They are usually installed on the cylinder’s side and they must be robust and protected against dirt and liquids.
Gefran Inc. 8 Low ell Ave Winchester, MA 1-888-888-4474 w w w .gefran.com North America 01890 [email protected]
By using a rod-style magnetostrictive linear sensor permanently mounted inside the cylinder, it’s possible to further protect the sensor from accidental damages but, of course, the solution is more expensive. Pressure transducers are instead requested for controlling different parts of the machine: air pressure and atomizing pressure are two important measurement in the spraying operation. Engine oil pressure needs to be monitored, too. Again. Pressure transducers are requested to be small, robust and protected against external agents. Gefran produces an entire range of linear resistive and magnetostrictive transducers and pressure transmitters with different option to fit every application. The PC67 series is the most robust resistive linear sensors, designed for mobile applications with an IP67 protection level.
The RK5 magnetostrictive series is available with a flanged head for the installation totally inside the cylinder and provides high-end performance in terms of accuracy and robustness.
Gefran Inc. 8 Low ell Ave Winchester, MA 1-888-888-4474 w w w .gefran.com North America 01890 [email protected]
The KS series is the best pressure transducer for mobile applications: based on thick film technology, it is miniaturized and it offers a high level of protection (IP67) and robustness that makes it one of the safest and most reliable sensors on the market (SIL2 certified).