Machine Design
Dynapar Hollow-Shaft Encoder Uses Phased-Array Sensing

Dynapar Hollow-Shaft Encoder Uses Phased-Array Sensing

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The redesigned HS35 vector-duty hollow-shaft encoder from Dynapar Corp., Gurnee, Ill. ( has several new features but the same old price. For example, the encoder now carries a 400-g shock rating and an unbreakable code disc. There’s also an option that extends its normal –40 to 70°C temperature range to –40 to 100°C. The device is RoHS and CE compliant.

The encoder relies on its ASIC-based phased-array sensing module. It lets the gap between sensor and disc be up to 10 times larger than the gap on traditional mask-on-sensor designs. The larger gap greatly reduces the risk of disc crashes. And the phased-array sensor requires fewer PCB components which improves service life. The array also has quadrature and symmetry functions embedded at the chip level, so there’s no need for external trimpots that can lead to signal drift.

The encoder does away with the glass disc common in most encoders where it is prone to break under shock or vibrations. Instead, a rigid plastic disc provides resolutions up to 5,000 ppr. The encoder also uses larger bearings than conventional encoders, which extends load capability and service life. Bearing life is rated at 80,000 hr at 3,600 rpm. The captured bearings are secured with retaining bolts for more-consistent attachment than traditionally used adhesives. This lets the bearings better resist runout. The encoder is electrically and thermally isolated on the shaft hub to minimize eddy-current buildup in vector-motor applications, a common problem when used with high-frequency drives.

The encoder is encased in an IP678-rated housing.

Edited by Stephen J. Mraz

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