Fastening device for belt pulleys

The combination comprising, a bearing housed in a belt pulley, a sealing disk covering the bearing clamped between the head of a screw and the inner ring of the roller bearing, means attaching said sealing disk 4 directly to the inner ring axially and radially and including projections 13, 14 extending into the bore of the inner ring to secure the screw 3 for transport.

BACKGROUND OF THE INVENTION
 It is already known from DE 4,242,293 that a belt pulley can be attached by
 means of a screw to the pivoting arm of a tensioning device. A sealing
 disk is clamped between the head of the screw and the lateral surface of
 the inner ring of the roller bearing to protect the roller bearing against
 the intrusion of dirt and other solid particles and to serve as a washer
 for the screw. When the belt pulley is fabricated and transported as a
 spare part for the known tensioning device or as an independent product
 for idling purposes, there is the danger that the accompanying screw and
 the sealing disk can fall out and be lost.
 SUMMARY OF THE INVENTION
 It is therefore an object of the present invention to create a fastening
 device for a belt pulley which can be transported and handled safely as a
 compact unit and without the loss of any of the individual parts.
 The task is accomplished in that the sealing disk is attached directly to
 the inner ring both axially and radially. The sealing disk has projections
 extending into the bore of the inner ring to secure the screw in the axial
 direction for transport.
 By attaching the sealing disk independently to the inner ring and the screw
 independently to the sealing disk, the invention creates a transport
 assembly which does not require any additional parts and does not lead to
 any significant extra expense. Sealing disk, screw, and pulley form a
 compact unit. The screw can turn freely but is secured in the axial
 direction.

DESCRIPTION OF THE METHOD AND SYSTEM
 Referring now to the drawings and particularly to FIG. 1, thereof, the belt
 pulley shown consists essentially of a sealed ball bearing 1, a molded-on
 pulley shell or housing 2, preferably made of plastic, and a fastening
 device D.sub.f. This device consists of a screw 3 and a sealing disk 4,
 which protects ball bearing 1 against sprayed water and hard particles.
 The disk 4 can be fabricated from a flat disk of sheet metal. The outer
 periphery of the disk 4 cooperates with the hub 2.sub.a of pulley shell 2
 to form a labyrinth seal 5.
 In the center of the disk 4, a cup-shaped, generally cylindrical stamped-in
 area 6 is provided having lateral surface 7 which is pressed into the bore
 B of the inner ring R.sub.i. A central hole 8 in the disk 4 accepts shaft
 9 of screw 3. The head of the screw 3 rests on the lateral surface 7 of
 the inner ring R.sub.i by way of sealing disk 4. A shaft 9 projects
 axially from the head 10 comprising a shaft section 11 adjacent to head 10
 of a larger diameter D than the diameter D.sub.1 of the shaft 9 which
 serves to center screw 3 with respect to the inner ring R.sub.i but still
 allows the screw to rotate.
 In the design according to FIG. 1, thicker shaft section 11 of screw 3
 continues in the axial direction as a shaft 9 of smaller diameter D.sub.i,
 which passes through central hole 8 in stamped cup 6. The radial surface S
 at the juncture of shaft sections 9 and 11 is peened over at a number of
 points around the periphery, thus forming radial projections 12 (see FIG.
 3). The projections 12 cooperate with the edge of hole 8, designed as a
 locking section 13, to form a positive interlock, which prevent screw 3
 from falling out in the axial direction.
 In the design according to FIG. 2, elastic tongues 14, which are
 distributed around the periphery, are formed on lateral surface 7 of cup 6
 and press at a slant in the axial/radial direction against thread 15 of
 shaft 9. As a result, a positive interlock which prevents screw 3 from
 falling out in the axial direction is again created.
 Even though particular embodiments of the present invention have been
 illustrated and described herein, it is not intended to limit the
 invention and changes and modifications may be made therein within the
 scope of the following claims.