US 5,859,425 AGranted

Encoder having first and second housing portions and guide means

AssigneeRuhlatec Industrieprodukte GmbH

InventorsKlaus Mleinek, Jurgen Kieselbach

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Abstract

An encoder includes a casing having an open end and a base which fits in the open end. Trapezoidal cutouts in the casing are arranged to receive partly trapezoidal projections on the base. The casing contains an optical sensor, a circuit board for operation of the sensor, and a timing disc mounted on a rotary hub. The hub has a passage for a drive shaft of a motor, and the passage is in register with an opening in the base. During assembly, the drive shaft is passed through the opening in the base and the motor and casing are urged towards one another to push the base into the casing. When the base enters the casing, the projections are received in the cutouts and a guide surface in the casing engages a centering surface on the hub. Once the projections are in the cutouts, the casing and the base are rotated relative to each other to secure the base to the casing. Due to the trapezoidal shape of the cutouts and the partly trapezoidal shape of the projections, the casing moves in a direction away from the base during rotation. This causes the guide surface of the casing to disengage from the centering surface of the hub.

An encoder, comprising a housing having a first housing portion and a separate second housing portion, one of said housing portions being receivable in the other of said housing portions, and said first and second housing portions respectively being provided with first and second coupling means for connecting said first and second housing portions to one another, one of said coupling means including at least one cutout, and the other of said coupling means including at least one projection receivable in said one cutout, said housing having an arcuate cross section, and said one projection and one cutout curving in circumferential direction of said housing, said first and second housing portions also respectively being provided with first and second guide means for adjusting said first and second housing portions relative to one another, and said first housing portion having a first outer periphery, said second housing portion having a second outer periphery, and one of said guide means including at least one guide surface in the region of the respective outer periphery;

a sensor receivable in said housing;
a circuit board receivable in said housing;
at least one encoding component receivable in said housing and including a codewheel, said housing being provided with a bearing section which is arranged to engage said one component during assembly of said encoder;
and a motor with a drive shaft, said motor having an end face, and said drive shaft including a shaft section which projects beyond said end face, said housing being connectible to said end face, and said shaft section being receivable in said housing when said housing is connected to said end face, said drive shaft having a first axis of rotation, and said one component having a second axis of rotation which is arranged to be in substantial register with said first axis, said bearing section including a substantially annular bearing surface having a third axis which is arranged to be in substantial register with said first and second axes.

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Abstract

Claims16