Disc brake pad return spring

#The present invention is directed to a return spring for pads in a disc brake system and, in particular, to a return spring with engagement legs that apply a torque to maintain the pads generally parallel to the rotor when in a non-braking state.

#In disc brake systems, it is common to employ return springs that return the disc brake pads to a rest position after braking. These springs come in a variety of shapes, including v-shapes. Typically, the ends of the springs engage the upper parts of the backing plates that support the brake, or friction pads. FIG. 1 is a partial top view 10 of a typical disc brake assembly wherein a v-shaped spring 1 is positioned between backing plates 3 that support friction pads 5. The v-shaped spring 1 exerts an outward force “F” on the pads 5 to urge each pad 5 away from respective outer surfaces 8 of the rotor 7, thus preventing drag, excessive pad wear, and excessive rotor wear during the non-braking condition.

#FIG. 2 illustrates the spring 1 in a typical installation and shows one of two opposed ears 9 that are commonly used to carry the backing plate. The ears 9 ride in a recess 12 in the mounting member 14. Engagement legs 11 at the end of each spring member 13 engage openings 15 in the backing plates 3. As shown in FIG. 4, the engagement legs 11 are perpendicular to the spring member 13. When positioned in the opening 15 in the backing plate 3 (see FIG. 3) the engagement leg 11 is generally parallel to the opposing sides of the opening 15.

#Reference is now made to the drawings of the invention wherein:

#FIG. 1 is a partial top view of a prior art disc brake assembly at rest;

#FIG. 2 is a partial side view of the assembly of FIG. 1;

#The present invention offers significant improvements in the operation of disc brake assemblies and longevity of brake components such as friction pads and rotors. Unlike many prior art disc brake assemblies, use of the inventive disc brake return spring maintains the friction pads in a generally parallel relationship with the rotor when at rest and in a non-braking state. Consequently, unwanted contact between the pads and rotors in the non-braking condition is eliminated or at least drastically reduced.

#Referring now to FIGS. 6-9, one embodiment of the inventive return spring is designated by the reference numeral 20 and includes a pair of spring members 21 that are joined by a connector portion 23. Each spring member terminates in an engagement leg 25 with a free end 27. Each engagement leg 25 is bent outward to form an angle a as shown in FIGS. 6 and 7, measured in a plane containing the two engagement legs and with respect to a line perpendicular to the plane containing the two spring members 21. It will be appreciated that the engagement legs 11 of the prior art design of FIG. 3 are parallel, whereas those of the invention diverge. Each leg 25 and its adjacent spring member 21 lie in a plane, and the leg 25 forms an angle β in that plane (see FIG. 7) that may be more than 90°.

#The orientation of the engagement legs 25 may be defined with respect to different reference lines, such as axes “fly” and “z” shown in FIG. 7, or a component of the brake assembly such as the rotor surface 8 or a wall of the opening 15 in the backing plate. The angle a is defined herein as lying in the plane containing both engagement legs, e.g., the plane formed by a “y” axis perpendicular to the plane containing the spring members and “z” axis lying in both the plane containing the spring members and the plane containing the engagement legs. The angle a is measured in the y-z plane from the y-axis. The directions of the engagement legs intersect in the y-z plane, and the “y” axis extends in the direction of the bisector of the angle of intersection. Thus, if the spring is symmetrical, the angle a is one half the angle of intersection.