Abstract:
A generally hat-shaped disc for a disc brake system is provided with an inner cylindrical surface serving as the drum of a drum in hat parking brake. A unitary backing plate supports the parking brake assembly and provides integral mounting parts for the fist type sliding caliper of the disc brake assembly.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to floating-caliper disc brakes for automotive vehicles, and more particularly to a hydraulic disc brake having a drum-in-hat parking brake associated therewith. 
     U.S. Pat. No. 4,228,726 discloses a hydraulic disc brake. When such a disc brake is used as a rear wheel brake on an automotive vehicle, provision must be made to include an emergency or parking brake. Previous attempts to incorporate an emergency or parking brake with a disc brake have resulted in complicated and costly mechanisms that have only gone into limited use. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention, a drum-in-hat type brake is associated with a hydraulic disc brake to serve as an emergency or parking brake. A unitary brake support casting serves as the drum brake backing plate and also replaces the disc brake anchor plate. Further, a labyrinthine seal between the brake support casting and the disc is provided by an annular projection on the disc and a corresponding groove in the brake support casting. 
     The invention is more fully explained hereinafter, reference being had to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an outboard elevational view of a hydraulic disc brake and drum-in-hat parking brake assembly constructed in accordance with the invention, the assembly as shown normally being associated with a left rear wheel of a vehicle, but being shown as it would appear with the wheel and wheel lug nuts removed; 
     FIG. 2 is an inboard elevational view of the assembly of FIG. 1, the disc and non-rotatable axle being omitted; 
     FIG. 3 is an elevational view of the assembly of FIG. 1, taken in the direction arrows 3--3 of FIG. 2, but partly broken away, partly in section, and partially showing the disc; 
     FIG. 4 is a view taken generally along the line 4--4 of FIG. 3, the disc being partially shown in section and the unitary casting, for supporting the drum-in-hat parking brake mechanism and the disc brake caliper, being partially shown in phantom; 
     FIG. 5 is an elevational view of an friction pad assembly for the caliper taken generally along the line 5--5 of FIGS. 3 and 4. 
     FIG. 6 is a sectional view taken generally along the line 6--6 of FIGS. 1 and 7; 
     FIG. 7 is a view similar to FIG. 1, taken along the line 7--7 of FIG. 8; 
     FIG. 8 is a view similar to FIG. 6, but with the stub axle broken away and the wheel hub and bearings omitted; 
     FIG. 9 is an enlarged sectional view taken generally along line 9---9 of FIG. 8, but with the disc omitted; and 
     FIG. 10 is an explosed view of the drum-in-that parking brake machanism, the hat-shaped disc being omitted. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to the drawings, FIG. 1 shows a hydraulic disc brake and drum-in-hat parking brake assembly 10 constructed in accordance with the invention and including a hat-shaped disc 12 and a floating fist type caliper 14. The hat-shaped disc 12 include a hat section 12a and a friction disc portion 12b. A non-rotatable stub axle 16 having a wheel mounting flange 22, better shown in FIG. 6, is secured to a fixed part 18 of the vehicle by a plurality of bolts 20 typically arranged as shown in FIG. 7. The wheel mounting flange 22 is rotatably mounted on stub axle 16 by means of tapered roller bearings 23 and 24. Wheel mounting flange 22 is provided with a plurality of wheel mounting studs 25 typically arranged a shown in FIG. 1. The disc 12 is mounted by its hat section 12a on studs 25 and against wheel mounting flange 22. The hat section 12a of disc 12 is retained on the studs 25 and against the mounting flange 22 by the wheel mounting lug nuts (not shown). Wheel mounting flange 22 is retained on stub axle 16 by nut 26 typically provided with a keyed washer 27 which engages an inner race of the bearing 23. 
     Besides securing stub axle 16 to the fixed part 18 of the vehicle, bolts 20 also secure casting 28 (FIGS. 2, 3, 4, 6, 7, 8, 9 and 10) in position. The brake support casting 28 supports the drum-type parking brake mechanism 30 for operative engagement with the inner peripheral surface 12c of the disc hat section 12a. Brake mechanism 30 includes a pair of typical drum brake shoes 31 and 32 having arcuate friction pads 33 or 34 typically attached to rim portions thereof, as best shown in FIGS. 7, 9, and 10. The side of the brake support casting 28 facing disc 12 has a plurality of raised pads 28a, 28b, and 28c (FIG. 10) for engagement with a web portion of brake shoe 31 and a plurality of raised pads 28d, 28e, and 28f for engagement with a web portion of brake shoe 32. Each brake shoe is held in engagement with the respective pads by a fastening pin 35 and a generally U-shaped spring member 36. 
     Each pin 35 extends through appropriate holes in the brake support casting 28, through the web portion of the respective brake shoe assembly, and through each leg of the respective spring member 36. The hole 36a in an outer leg of each of the spring member has an elongate rectangular shape, and the ends of the pins 35 are compressed or upset to provide free end portions 35a of a generally corresponding elongate rectangular shape. After insertion of pin 35 through spring member 36, the pin is rotated ninety degrees so that the longer dimension of its end portion 35a extends across the shorter dimension of hole 36a in the outer leg of the spring member. Further, the end portion of each pin 35 rests in a groove in an outer leg of the respective spring member 36 after assembly, with the longer dimension of the end portion extending lengthwise of the groove, to prevent inadvertent rotation of the pin 35 to a releasing position, as best shown in FIGS. 7 and 8. Each pin 35 is provided with an enlarged head 35b larger than the corresponding hole in the brake support casting 28. 
     The brake support casting 28 is also provided with a rotation-preventing abutment 28g slotted at opposite arcuate ends with slots 28h and 28i. The brake shoes 31 and 32 are also held in engagement with the respective pad portions 28a-28f by the disposition of arcuate end portions 31a and 32a of the brake shoe webs respectively in the slots 28h and 28i. 
     The brake shoes 31 and 32 are urged toward each other by tension spring 37 connecting one pair of adjacent arcuate ends and tension spring 38 connecting the opposite pair of adjacent arcuate ends of the brake shoe webs. Brake shoes 31 and 32 are held apart, adjacent the spring 38, by the torque receiving abutment 28g and adjacent spring 37 by a typical drum brake wear-adjusting mechanism including screw 40 with slotted head 40a receiving therein a notched portion 31b of the web of brake shoe 31, starwheel 42, and sleeve 44 slotted at an end remote from the starwheel 42, at 44a, to receive notched portion 32b of the web of brake shoe 32. As the friction pads 33 and 34 become worn, turning starwheel 42 farther away from the head of the screw 40 moves the sleeve 44 to spread the brake shoes 31 and 32 farther apart. 
     The means for opening the parking brake mechanism 30 is shown in FIGS. 9 and 10. An elongate floating bracket 46 typically includes two arms 46a and 46b welded together. Bracket 46 is provided with slot 46c for receiving a notched portion 31c of the web of brake shoe 31. At the opposite end, arm 46a is provided with a bent-over tab 46d which engages raised pad 28j on the brake support casting 28. Between the ends, arms 46a and 46b diverge to receive a rotatable lever 48 pivoted on pin 50 and provided with snap ring 51. One end portion 48a of the lever 48 engages notched portion 32c of the web of brake shoe 32. The opposite end 48b of lever 48 is generally U-shaped for receiving parking brake cable 54 having a typically enlarged end 54a as an anchor or stop. A compression spring 56 typically traps cable 54 in the U-shaped end 48b, as shown in FIG. 9. An elastomeric seal 58 for aperture 28k  through which cable 54 enters is typically held in place by a spring clip 59. 
     When cable 54 is pulled by operation of a hand lever accessible from the driver&#39;s seat of the vehicle, lever 48 is pivoted in a direction to spread brake shoes 31 and 32 apart thereby engaging the friction pads 33 and 34 with the inner peripheral surface 12c of the disc hat section 12a. The abutment 28g prevents the brake shoes 31 and 32 from rotating in either direction. 
     Typically, aperture 28m is provided in the brake support casting 28 to afford access to starwheel 42 for manual adjustment. A removable plug 60 normally seals aperture 28m. Four mounting holes 28n are provided in the brake support casting 28 for reception of the bolts 20. Further, opening 28w is provided for reception therethrough of stub axle 16. 
     Brake support casting 28 further includes a pair of circumferentially spaced arms 28p and 28q extending from the generally circular portion 28x and having a pair of guide rails 28r and 28s respectively at their outer ends. Casting 28 also includes a pair of generally cylindrical ears 28t and 28u (FIGS. 2, 3 and 4) provided with axially extending internally threaded holes. Disc brake caliper 14 is typically attached to casting 28 by a pair of caliper supporting pin assemblies comprising bolt 61 extending through sleeve 63 and threaded respectively into ears 28t and 28u. 
     Inboard leg 14a of the caliper 14 includes a hydraulic cylinder 14b and a pair of apertured lugs 14c and 14d disposed on opposite sides of the cylinder 14b. Each of the lugs 14c and 14d has a typical rubber bushing 64 extending therethrough as shown in FIG. 3. Bushings 64 protect the caliper support pin assemblies against dirt and dust. 
     Cylinder 14b has an inlet port 14e (FIG. 2) adapted to have a hydraulic line attached thereto. A bleed port is typically provided with a fitting 66 covered with a dust cap 67. A piston 68, fragmentarily shown in FIG. 3, is reciprocably mounted in the cylinder 14b and has an exposed end abutting the inboard friction pad backing plate 69. The periphery of the exposed end of the piston 68 is typically protected by dust boot 70. A spring clip 71 riveted to the backing plate 69 and received in a recess in the exposed end of the piston 68 secures the backing plate 69 to the piston 68. A seal 65 is typically provided on the piston 68 to prevent leakage of hydraulic fluid. 
     An outboard leg 14f of the caliper 14 has an outboard backing plate 73 secured thereto by a spring clip 75 rivetted to the backing plate. The backing plate 73 has a friction pad 74 bonded thereto and engageable with an outboard side of the friction disc portion 12b. 
     As can be seen in FIG. 2 for the inboard friction pad backing plate 69, which is shaped the same as the outboard friction pad backing plate 73, the backing plates are notched at their lower ends to engage three sides of the guide rail 28s and shaped at their upper ends as shown, to embrace two perpendicular sides of the guide rail 28r. Further, the outboard leg 14f has a projection 14g which engages the guide rail 28r on one side and a projection 14h which engages the rail guide 28s on two sides, as shown in FIGS. 1, 3, and 7. The backing plate 73 with two notches 73a and 73b is shown in FIG. 5. 
     As shown in FIGS. 4, 6, and 8, the disc 12 is provided with an annular projection 12d extending from the inboard side of the friction disc portion 12b oppositely from the hat 12a, and as shown in FIG. 10, the brake support casting 28 is provided with an annular groove 28y. The projection 12d and the groove 28y thereby provide a laybrinthine seal, as can be seen in FIGS. 6 and 8. 
     Various modifications may be made in the structure shown and described without departing from the scope of the invention.