Minneapolis, MN--Faced with the challenge of controlling pressures on air-operated components such as torque limiters, clutches, or brakes, designers often turn to multiple air circuits to provide multiple air-pressure levels.
For example, in a clutch/brake application, a designer might use dual air circuits to apply a high level of torque at the beginning of a cycle to overcome startup inertia, and then lower the torque to a level that will keep the motion going. That approach enables the appropriate pressures to be applied at various points in an operating cycle, but requires manual setup; may need periodic adjustment to compensate for variations in operation; and calls for a number of valves, switches, and gauges that grows with the number of different pressures required.
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| The torque limiter controller integrates all of the mechanical and electrical functions of dual pressure circuit into a compact electronic device. |
A new device called a torque-limiting controller (TLC) integrates all of the mechanical and electrical functions of a multiple pressure circuit, eliminating the need for numerous valves, switches,and gauges and their associated hoses and fittings. A microprocessor allows users to choose among 16 air-pressure levels between 0 and 80 psi based on a four-bit digital input. An option to provide output pressure based on an 0-10V analog signal allows the device to produce pressure proportional to the signal continuously in the 0 to 80 psi range.
The heart of the device, the microprocessor, senses current pressure and adjusts pneumatic valves as needed to match the output pressure with the desired set point. Accuracy is ±0.25% at 25C and 100 psi input.
| A conventional dual air circuit features a complex assembly of valves, gauges, regulators, and the associated hoses and fittings. |
The pressure output as a function of input pressure is determined, in the digital mode, from a table stored in the microprocessor. A default standard table can be used or the user can customize the table for specific requirements.
The TLC also boasts a built-in safety feature. In the event of the need to exhaust air pressure, such as when the torque limiter is overloaded, the TLC senses an external switch closure, exhausts the air pressure, and provides an indication of alarm status.
Additional details…Contact Horton Industrial Products Inc., 1170 15th Ave. SE, Minneapolis, MN 55415; (612) 331-5931; or Circle 506.
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