EPC's Encoders Help Stop West Nile Virus

The Problem

Clarke was looking to replace the encoder on their mobile pesticide application machine, which works by atomizing insecticide to a specific droplet size. The droplets create a fog plume, which minimizes the pesticide residue that is released into the environment when the machine is deployed to combat mosquitoes in an area. As a mobile unit, the machine is often driven over rugged terrain, exposing it to a lot of dust and contaminants. This high-revving machine combined with the bumpy mobile environment created extreme vibrations that the encoder could not withstand.

Clarke had been using an encoder with a plastic housing. The vibrations occurring during regular use were causing the plastic housing to flex and distort, resulting in misalignment of the optical sensor with the LED and code disk. This misalignment caused poor quality waveform and lost counts, which impacted the control system’s ability to accurately monitor motor speed. In extreme cases, disk crash could occur, a condition in which the rotating code disk contacts the sensor, damaging both components.

Machine shutdowns were frequent. Equipment downtime and expensive service calls were a major headache to Clarke – and their customers. In addition to the added expense of downtime, timing is critical in mosquito abatement and preventing the spread of disease.

Clarke needed a rugged, durable encoder that could maintain reliable optics alignment even when exposed to frequent shock and vibration. The encoder also needed to be simple to mount to the motor, resistant to dust and debris, and able to operate both in high temperatures and at speeds up to 30,000 RPMs.

Summary of encoder requirements for this application:

• Rugged housing able to withstand extreme vibration
• Reliable alignment of optics
• Durability
• Reliability
• High-temp operation
• Simple mounting
• Adequate sealing to protect encoder

The Solution

EPC Applications Engineers worked closely with Clarke to address not only what wasn’t working with the encoder on their unit, but to fine-tune what was working, and identify what could work better.

After considering the cause of Clarke’s encoder failures and all the application requirements, EPC’s engineers opted to design a customized version of the Model 121 Auto Aligning Modular Encoder. This rugged, all-metal, bearingless encoder was designed to virtually eliminate warping and deflection of the housing caused by hard shock and vibration. This design was the key to solving Clarke’s encoder problem.

With stable optical alignment and the advanced Opto-ASIC sensor technology of the Model 121, EPC’s engineers were able to work with Clarke to obtain more precise measurement of the atomizer’s speed. This enabled more accurate control of pesticide dilution during application, while ensuring reliable service and reduced operating expense due to field failures.

Addressing the need for hassle-free installation, the innovative and patented design of the Model 121 requires no calibration, gapping or special tools when mounting to the motor. The Model 121 is also able to withstand the 30,000 RPM speeds at which the Clarke unit operates. In addition, it can operate in temperatures up to 100° C and comes equipped with an IP50 dust seal kit.

All of these features guarantee that the Model 121 operates reliably over the full range of the pesticide machine’s operating conditions. Since switching to the Model 121, Clarke has not had an encoder failure on any of the upgraded machines.

Resources

Do you have a question about which encoder is right for your application? When you contact EPC, you talk to engineers and encoder experts for your toughest encoder questions. You’ll get answers that make sense for your application.

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Contact EPC to find the right encoder for your application.

Model 121 Auto-Aligning Modular Encoder

The Model 121 incorporates the latest Optical ASIC technology for enhanced performance. The all-metal construction eliminates warping and deflection.

Model 121 Key features:

• Simple, hassle free mounting
  Accepts larger shafts up to 5/8” (or 15 mm)
• Up to 12-pole commutation available
• 0° to 100° C operating temperature available
• Patented design
• Includes IP50 dust seal kit
• Bearingless