Disc Brake Parking Cartridge Retention Device

This invention relates to a disc brake having a mechanical parking brake actuator attached thereto.

A disc brake comprises a caliper assembly having a bore with a piston assembly therein so that when fluid pressure is communicated to the bore during a service brake application, the caliper assembly engages the pair of friction elements with the rotor. Numerous parking brake devices have been developed in order to mechanically actuate the piston for a parking application. A parking brake application may be effected by various devices such as ball ramps or screw threads which mechanically actuate or bias the pair of friction elements into engagement with the disc. Such parking brake mechanical actuator devices include a double toggle device such as that disclosed in U.S. Pat. No. 4,544,045 entitled "Mechanical Actuator for a Disc Brake", and Ser. No. 576,512 entitled "A Disc Brake Assembly". U.S. Pat. No. 4,544,045 discloses a double toggle mechanical actuator device disposed within a bore of the caliper housing, one end of the bore being enclosed by a cap threadedly inserted into and received by the bore. U.S. patent application Ser. No. 576,512 discloses a double toggle device contained within a parking cartridge housing assembly which is received within the bore of the caliper housing and secured thereto by means of a snap ring. A bracket is attached to the top of the parking cartridge housing and provides support for a cable attached to lever arms of the mechanical actuator. It has been known to provide hydraulic cylinders which have long bolts that retain end caps over ends of the cylinders in order to carry the cylinder loads. However, it is desirable to provide a disc brake with a parking actuator mechanism contained within a separate parking cartridge housing that is easily attached to and removed from the caliper housing, wherein the cartridge housing can be made of a light weight material and relatively small size, and the parking cartridge housing attached to the caliper housing in such a manner that the cartridge housing does not have imposed thereon reaction forces created during actuation of the mechanical parking actuator. Thus, it is desirable to secure the parking cartridge housing to the caliper assembly in such a manner that the parking cartridge housing does not experience the reaction forces, and yet provide a parking cartridge housing that is easily assembled and removed so that the parking actuator mechanism may be handled as a unit.

The present invention comprises a disc brake having a mechanical parking actuator, the disc brake having a caliper assembly cooperating with at least one friction pad to engage the friction pad with the rotor, the caliper assembly including a caliper housing with a bore receiving a piston assembly which is movable in the bore to engage the friction pad with the rotor, a parking cartridge housing with an opening therein and attached to said caliper housing so that the opening is aligned with the bore, plug means disposed within the opening in order to enclose the opening at an end of the cartridge housing, a mechanical parking actuator disposed within said opening and bore, end enclosure means abutting against and extending across the end of the parking cartridge housing, and a plurality of securement devices each being secured at one end with the caliper housing and at the other end with the end enclosure means so that the end enclosure means and securement devices cooperate to receive reaction forces exerted against the plug means and transmit the forces directly to the caliper housing. The mechanical parking actuator comprises a pair of exterior levers which are displaced by means of a cable, with a retainer or pin securing together the cable and respective ends of the levers so that the levers move with the cable.

The invention will now be described with reference to the accompanying drawings, wherein:

FIG. 1 is an end view of the disc brake and with parking cartridge device;

FIG. 2 is a section view taken along view lines 2--2 of FIG. 1; and

FIG. 3 is a top section view of the retainer securing together the cable and respective ends of the levers; and

FIG. 4 is a top view of an alternative structure for securing together the cable and levers.

FIGS. 1 and 2 illustrate a disc brake 10 with a parking cartidge device 28 disposed at an end thereof. The disc brake includes a caliper housing 12 having a bore 14 with a piston 16 therein. Piston 16 engages friction pad 18 so that fluid communicated to bore 32 biases the piston 16 against friction pad 18 and rotor 20. As is well known in the art, reaction forces displace the caliper assembly so that caliper leg 22 displaces outer friction pad 24 against the other side of the rotor 20. Disc brake 10 includes a friction pad wear compensation mechanism 26 (of the type disclosed in application Ser. No. 576,512) disposed interiorily within the bore 32 and engaging the piston 16. Parking cartidge device 28 includes a parking cartridge housing 30 abutting end 13 of the caliper housing and having a through opening 34 with a double toggle mechanical parking actuator 36 therein. The double toggle mechanical parking actuator 36 engages at one end via toggle 38 an end plug 48 and at the other end via toggle 39 a piston 40, and is provided in accordance with the double toggle mechanical actuator disclosed in U.S. Pat. No. 4,544,045 and Ser. No. 576,512, each incorporated by reference herein. Parking cartridge housing 30 includes a plurality of longitudinal openings 42 for bolts 50 which extend therethrough and are threadedly received in threaded tappings 44 of caliper housing 12. Bolt heads 52 are secured against a bracket 60 which extends across end 33 of parking cartridge housing 30 so that bracket 60 captures end plug 48 within through opening 34. The bracket 60 extends upwardly to provide an opening 62 receiving cable bushing 64 therein. The double toggle mechanical actuator 36 includes a pair of lever arms 70 which extend adjacent the bracket 60 and are captured together by U-shaped retainer 80 that secures the lever arms together and captures cable end 92 therein. The cable 90 has a crimp member 91 at end 92 and the cable extends through retainer opening 85, lever arm ends 72 and bushing 64 for attachment to the parking brake lever (not shown). Lever arm ends 72 include recessed areas 74 which permit the U-shaped retainer 80 to be positioned relative to the lever arms, and retainer 80 includes inwardly directed fastening barbs 84 at the end of each leg 82, the fastening barbs engaging the sides of lever arms 70 so that the retainer is secured thereto. Lever arm ends 72 are held together and in position by the snap-on retainer 80, which also serves to secure the cable to the lever arms 70.

When the vehicle operator desires to set the parking brake, the parking brake lever (not shown) is operated and this displaces the operatively attached cable 90. Cable 90 is displaced in the direction of Arrow A to move levers 70 to their dotted line position illustrated in FIG. 2. The cable is slidably journalled through the bushing 64, with bushing 64 fixedly positioned by the bracket 60. Rotation of lever arms 70 causes operation of the mechanical parking actuator 36. As the cam 37 rotates, the input reaction toggle 38 and the output toggle 39 are rotated therewith. The output toggle 39 causes lateral displacement of the piston 40 and connected friction pad wear compensation mechanism 26. This action causes a similar reaction through reaction toggle 38 which exerts reaction forces against the end plug 48. The end plug 48 is disposed directly against bracket 60 which receives all of the reaction forces and transmits them directly to the heads 52 of bolts 50. The bolts 50 transmit the reaction forces directly to their threaded ends secured in the threaded tappings 44 of caliper housing 12. Thus, reaction forces produced as a result of actuation of the parking brake mechanical parking actuator 36 are transmitted directly to the bracket 60, bolt heads 52, bolts 50, threaded tappings 44, and caliper housing 12, without the parking cartridge housing 30 being subjected to any of these reaction forces. As a result, parking cartridge housing 30 may be made of a much lighter weight material and of a generally smaller configuration since it is not subjected to reaction forces. Additionally, parking cartridge housing 30 provides an easily assembled and easily removed cartridge for the mechanical parking actuator 36 so that the entire assembly may be easily attached or removed for assembly or servicing. Also, the bolts can be loosened so that the piston 16 and parking cartridge device 28 can be pushed back for clearance between the disc and shoe linings, if such is desired. Another advantage is that end plug 48 may be simply inserted within opening 34. Previously, end plug 48 had threads thereon which were threadedly received in threads of the parking cartridge housing. As a result of plug 48 being captured within through opening 34 by means of bracket 60, the threaded connection between the parking cartridge housing and the plug has been eliminated, thus eliminating manufacturing costs and reducing disassembly time. Bolts 50 provide not only for the direct transmission of reaction forces to the caliper housing, but eliminate the previously used shear ring for retention of the parking cartridge housing to the caliper housing. This provides a more reliable and stronger connection of the parking cartridge housing to the caliper housing, in addition to providing a more readily removable connection. An additional significant advantage is that the end bracket 60 not only serves to transmit the reaction forces directly to the bolts which are attached to the caliper housing, but extends upwardly to provide positioning for the bushing 64 and cable 90. Instead of being a separate construction attached to the cartridge housing merely for the purpose of positioning the cable, the bracket serves the dual purposes of transmitting reaction forces and positioning the cable.

Double toggle mechanical parking actuator 36 has the pair of lever arms 70 rotated by cable 90. U-shaped retainer 80 captures together cable end 92 and lever arm ends 72 and eliminates a clevis pin bracket (see Ser. No. 576,512) utilized previously for securing the cable to the lever arms. As a result, the distance "B" between the at-rest position of lever arms 70 and bracket 60 has been substantially reduced because the clevis pin bracket is no longer positioned between the lever arms and bracket 60. Thus, the lever arms are positioned closer to the bracket and this reduces width and space requirements for the disc brake parking cartridge assembly.

FIG. 4 illustrates an alternative method for attaching the cable 90 to the lever arm ends 72. Pin 100 extends through lever arm openings 73 and is maintained in position by cotter keys or pins 76. Pin 100 has a bore 102 receiving end 92 of cable 90, with crimp member 91 abutting pin 100. Pin 100 provides a very strong and reliable means for maintaining the cable attachment with the lever arms.

Although the present invention has been illustrated and described in connection with example embodiments, it will be understood that this is illustrative of the invention and is by no means restrictive thereof. It is reasonably to be expected that those skilled in the art can make numerous revisions and additions to the invention and it is intended that such revisions and additions will be included in the scope of the following claims as equivalents of the invention.