Disc brake tone ring

An assembly for an induction sensing tone ring is provided. A brake rotor includes a circular pocket. A tone ring is received in the circular pocket of the brake rotor. The brake rotor has a plurality of locating tabs, with each locating tab having a slope surface. The tone ring has a plurality of retaining tabs, with each retaining tab being received between two locating tabs of the brake rotor. A retaining ring is fitted in each locating tab slope surface of the brake rotor to press fit against the retaining tabs of the tone ring.

BACKGROUND OF THE INVENTION

The present application relates to a method and an assembly including an inductive tone ring attached to a rotating part for speed and position sensing purposes.

The use of inductive tone rings for positional sensing, as in anti-lock brake applications, is known. However, the installation of the anti-lock brake system sensing ring, particularly to a disc brake rotor, has caused concern. Such concerns include difficult installation and replacement, the use of bolts and screws which can loosen or fail, and thermal transfer from the brake rotor to the tone ring causing dissimilar thermal expansion and warpage. Corrosion of the tone ring or tone ring features formed into the brake rotor is also a major cause of field issues. Often the tone ring will corrode beyond a usable condition prior to the wear limit of the rotor being met.

Accordingly, an improved arrangement and method for installing an inductive tone ring with a disc brake rotor assembly is provided.

SUMMARY OF THE INVENTION

An improved arrangement and method for attaching an inductive tone ring to a rotating part, which in the current manifestation is a brake rotor but could also be applied to a wheel hub, machine spindle or other rotating part in which rotational position or speed measurement is required.

The method as applied to a disc brake assembly comprises a brake rotor having an internal wall forming a circular pocket. An anti-lock brake tone ring is received in the circular pocket adjacent pocket adjacent a top surface of the brake rotor. The brake rotor internal wall includes a plurality of protruding members each having a retaining groove with an upper inclined surface formed in the internal wall of the brake rotor forming the circular pocket.

The tone ring has a plurality of retaining tabs. Each tone ring retaining tab is positioned between two of the brake rotor internal wall protruding members. A retaining ring is fitted into each of the brake rotor protruding member retaining grooves. The retaining ring presses against each of the retaining tabs of the tone ring.

The advantages of the improved tone ring attachment method of the present invention include reduced areas of contact between the brake rotor and the tone ring resulting in a reduction of thermal transfer from the brake rotor to the tone ring. The ring is not rigidly constrained, allowing it to “float” within the rotor attachment to avoid the warping at high temperatures that can occur if the ring is rigidly mounted to the rotor with screws or bolts. Corrosion effects are reduced as a result of the lower temperatures and minimal contact between the tone ring and the rotor. The elimination of screws, bolts or press-fits in the attachment of the tone ring to the brake rotor eases installation and replacement. Further, no drilling or tapping of screw or bolt holes in the rotor is required in order to prepare the rotor to receive the tone ring. The tone ring of the present invention is simply placed into position in the circular pocket of the brake rotor internal wall in engagement with the plurality of protruding members each having a retaining groove. The retaining ring is then fitted into each of the brake rotor protruding member retaining grooves. The retaining ring presses against each of the retaining tabs of the tone ring.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now toFIGS. 1-3, a disc brake assembly in accordance with a first embodiment of the present invention is shown generally at10. A circular shaped brake rotor is shown at12, with the usual material for brake rotor12being cast iron. Brake rotor12includes internal wall14which forms circular pocket16. Snap retaining ring30is received in circular pocket16. Snap retaining30is a circular shaped ring.

Tone ring20is placed adjacent ridge15extending from upper surface21of brake rotor12. Tone ring12further includes an axially inner facing lip41in radial contact with a radially inward facing surface43of ridge15of brake rotor12. Tone ring20is comprised of steel or other ferromagnetic materials that are known for use in such inductive tone rings.

Brake rotor12further includes a plurality of locating tabs17. Each locating tab17includes a sloped surface19formed around and facing radially into circular pocket16. Slope surface19of each locating tab contacts retaining ring30to force retaining ring19against a retaining tab31of tone ring20. Each retaining tab31of tone ring20is fitted between two locating tabs17of brake rotor12to thusly restrict the rotation of tone ring20within brake rotor12.

Tone ring20is seen to include inner lip41and upper surface34. Inner lip41of tone ring20is fit adjacent a radially inward facing surface43of ridge15of brake rotor12to center the tone ring20about the rotating axis. A plurality of retaining tabs31extend radially inward from tone ring20.

Upon assembly of disc brake assembly10, tone ring20is placed on one side of brake rotor12adjacent ridge15extending from surface21of brake rotor12. Tone ring12axially inner facing lip41is then in radial contact with a radially inward facing surface43of ridge15of brake rotor12. Brake rotor12further includes a plurality of locating tabs17. Each locating tab17includes a sloped surface19formed around and facing radially into circular pocket16. Slope surface19of each locating tab contacts retaining ring30to force retaining ring19against a retaining tab31of tone ring20. Each retaining tab31of tone ring20is fitted between two locating tabs17of brake rotor12to thusly restrict the rotation of tone ring20within brake rotor12.