New Encoders With Inductive All-round Scanning In Hollow Shaft Design

With fewer components, the new encoders create an increase in performance and guarantee guaranteed wear-free operation. They also set new standards in the achievable control dynamics, reliability and functionality. They also open up new applications for inductive encoders, e.g. B. on highly dynamic motors, drive modules and machine components that require a corresponding hollow shaft of the measuring device.

Alternative multiturn variant

The ECI 4000 single-turn version has a resolution of 20 bits. As an alternative, Heidenhain also offers the EBI 4000, a multiturn version that has a revolution counter option with a resolution of 16 bits and is buffered by an external battery. The new inductive rotary encoders consist of a scanning unit and graduation drum. With a height of only 20 mm, they offer outstanding device properties.

The scanning is carried out as a so-called all-round scanning. The complete graduation structure of the graduation drum (rotor) with the associated scanning band of the scanning unit (stator) is involved in obtaining the position signal. In this way, the encoder evaluates two incremental scan tracks of different periodicity. This scanning principle has an extremely positive effect on the mounting tolerances and the position accuracy. In addition, it largely compensates for position deviations over the entire speed range of up to 6000 min ^-1, such as those that occur when the pivot point of the drive shaft is offset.

Equipped with a digital interface

The new inductive encoders ECI 4000 and EBI 4000 are equipped with the digital EnDat 2.2 interface. In addition to interference-free transmission, the EnDat 2.2 interface also supports other device-specific functions, e.g. B. the transmission of the data of an internal and an external temperature sensor or the provision of the standardized evaluation numbers for signal diagnosis. The output of these operating parameters in a closed control loop allows permanent condition monitoring of the measuring device. The Drive-Cliq interface, which is optionally available for the single-turn version, offers additional connection options.

Certification for SIL 2 applications in accordance with EN 61508 is planned for the devices. With appropriate additional measures in the subsequent electronics, the safety level for the EnDat 2.2 devices can then also be raised to SIL 3. The relevant error exclusion criteria for a safe mechanical coupling are of course part of the certification.

Easy to assemble and integrate

The basic design of the devices includes their ease of installation and the application-oriented design for integration in motors and machines. Among other things, they meet protection class IP40. Thanks to an outer and an inner centering diameter on the scanning unit or graduation drum, they can be installed and put into operation quickly and without additional adjustment or testing tools. An application-related axial offset of the graduation drum to the scanning unit is tolerated in the range of ± 1.5 mm. The maximum concentricity tolerance of the drive shaft is similarly generous at 0.2 mm.

The working temperature range for devices with EnDat 2.2 interface is up to 115 ° C. The vibration resistance is 400 m / s² for the stator and 600 m / s² for the rotor according to EN 60068-2-6. This ensures a high level of robustness when used as an engine feedback system - especially if the engine is extremely performance-oriented. (jv)

SPS IPC Drives 2016: Hall 7, Stand 190