Rotary encoders
A rotary encoder is a sensor that converts the rotation amount, direction, and speed of a shaft into electrical pulses. Incremental types output two channels, A-phase and B-phase, which are offset in phase. The pulse count gives the rotation angle and speed, and the phase lead or lag indicates the direction of rotation. Detection methods include optical and magnetic types. Magnetic types are non-contact, have no wear, and are resistant to oil and dust. Many listed products are bearing unit types that integrate a deep groove ball bearing with the sensor. They are used for motor rotation detection, motor control in electric and hybrid vehicles, steer-by-wire in industrial vehicles, and rotation detection of pulleys and rollers.
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Rotary encoders
SKF Roller Encoder Unit
Model: AHE-5509 A
A plug-and-play bearing unit with an integrated encoder for applications where the outer ring rotates. Can be incorporated into pulleys, rollers and similar components.
SKF
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Rotary encoders
SKF Steering Encoder Unit
Plug-and-play steering input device for steer-by-wire systems. Detects steering with a non-contact incremental sensor and outputs two redundant signal channels.
SKF
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Rotary encoders
Motor Encoder Unit (BMB/BMO Series)
Motor encoder unit integrated with a bearing. Multiple sizes with bore diameters of 15 to 45 mm are available, and model numbers differ by pulse count and output cable length.
SKF
How to choose Rotary encoders
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1. Select pulse count based on required angular resolution
The number of pulses per revolution determines the smallest detectable angle. Listed products have a relatively low count of 32 to 80 pulses/rev, suited to motor speed control and steering detection. Counting both edges of A and B phases (4x multiplication) quadruples the effective resolution, so confirm the required value together with the processing method of the controller.
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2. Allow margin in maximum rotational speed
The maximum rotational speed of listed products ranges widely from 300 to 14000 r/min. Confirm that the application's top speed has sufficient margin. Also confirm that the output frequency, determined by rotational speed multiplied by pulse count, falls within the input frequency capability of the receiving-side counter.
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3. Select a bearing unit with bore matching the shaft diameter
For bearing-integrated types, the bore must match the diameter of the mounting shaft. Listed products have bores of 15 to 45 mm, with sizes divided by shaft diameter. Check the fit tolerance and axial positioning method against the drawings, assuming use as a bearing.
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4. Check mounting space by outer diameter and mass
Outer diameters range from 35 to 85 mm, and masses from 0.07 to 0.53 kg. Check interference with the motor housing or pulley interior, including the cable exit direction. When mounting on a rotating body, consider the effect of mass on inertia and vibration.
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5. Match supply voltage to the control circuit
Listed products operate on a supply voltage of 5 to 12 V DC. Confirm that it matches the available power supply, and that the output signal voltage level and output circuit type meet the input specifications of the receiving side. For automotive applications, also confirm tolerance to supply voltage fluctuations.
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6. Verify phase difference, duty ratio, and cycle accuracy
Large variations in the phase difference between A and B phases (normally 90°), duty ratio, or cycle accuracy can cause direction determination errors and speed detection fluctuations. For high-precision speed control, check in the specifications that these tolerances meet the control requirements.
This guide was written by AI based on the listed products' documents and specification items. Check each manufacturer's documents before adopting.