Abstract:
A heat shield installation on a tire supporting wheel and brake assembly having a rim member with an inner surface that surrounds a heat sink composed of stator and rotor brake discs. A plurality of circumferentially spaced drive keys are located between the heat sink and the inner surface of the rim member with such keys slidably mounting the rotor discs. A heat shield is located between the inner surface and the drive keys with a plurality of circumferentially spaced spacers secured thereto. Fastener members interconnect the drive keys to the rim members through the spacers while securely locking the heat shield radially and axially relative to the rim member of the tire supporting wheel.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a multi-disc aircraft brake system and more particularly to a new and improved heat shield installation for an aircraft multi-disc friction braking system. 
     During the braking of an aircraft, the alternately splined stator and rotor discs of the multi-disc brakes are brought into sliding contact with each other, generating considerable heat energy that must be dissipated to eliminate the highly deteriorative effects on the wheel and tire structure which, in certain instances such as abortive or rejected take-off, can result in sufficiently high heat to result in tire ruptures or fires. 
     As the heat, heat energy or brake energy is generated within the braking elements of the stators and rotors (hereinafter also referred to as the heat sink), such heat energy is dissipated via conduction, radiation and convection to the adjacent braking components, such as the wheel assembly, bearings, pistons and other adjacent structures. It is important to limit the heat transfer to protect the structures as much as possible. One manner of protecting these areas is to provide a heat shield between the heat generating elements of the (stator and rotors) heat sink and the wheel assembly, and its adjacent components and bearings. 
     The heat shield is attached to the wheel usually by numerous bolts and thus tend to conduct heat from the shield into the wheel at the numerous bolted points of mounting. It is object of the present invention to provide means for securing the wheel heat shield to the wheel in such a way that the conduction of thermal energy into the wheel and its adjacent structures is minimized by eliminating entirely the heat shield bolted connection to the wheel. With the use of specially designed spacers in cooperative action with the torque bars the heat shield is held more securely in place both axially as well as tangentially. The torque bars also provide multiple points of contact around the circumference of the full circle heat shield to provide rigidity in the radial direction without affecting the accuracy of location of the torque bar thus providing a more efficient heat shield system. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a tire supporting wheel and brake assembly wherein the wheel has a rim member with an inner surface that surrounds a heat sink composed of a plurality of stator and rotor brake discs. The stators are slidably connected to a torque tube that is connected to the stationary portion of the wheel supporting structures while the rotors are slidably mounted to circumferentially spaced keys that are connected to the rotatable wheel. A heat shield is located in the clearance space between the inner surface of rim member and the circumferentially spaced keys and are interconnected by a plurality of circumferentially spaced spacers which fixedly secure the heat shield in a radial position as well as an axial position relative to the central axis of the tire supporting wheel. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary cross-sectional view of a brake of a brake assembly with a heat shield installation therein; 
     FIG. 2 is a side elevational view partly in cross-section of a portion of a heat shield secured to a rim member and a drive key by a spacer; 
     FIG. 3 is a front elevational view of a portion of the heat shield and its mounting taken on line 3--3 of FIG. 2; 
     FIG. 4 is an exploded perspective view of the spacer and a portion of the heat shield with a reinforced aperture therein. 
    
    
     DETAILED DESCRIPTION 
     Referring to the drawings, wherein like reference numerals designate like or corresponding parts throughout the several views, there is shown in FIG. 1 a friction brake mechanism 10 for use with a cylindrical wheel 11, having matching wheel sections 12 and 13. Each of the wheel sections 12 and 13 has a rim member 14 and 15, web member 16 and 17, and hub members 18 and 19. The wheel sections 12 and 13 are fastened together by suitable bolts disposed in aligned bores within web members 16 and 17 to form an integral unit therewith. 
     The hub members 18 and 19 are supported for rotation on bearings 22 which are mounted on a nonrotatable axle member 23. A stationary carrier or boss 24 with a circumferentially extending flange 25 is suitably mounted on stationary axle 23. Flange 25 has a plurality of circumferentially spaced bores to receive bolts 26 for securing such flange to one end of a cylindrical torque tube member or torque tube 27. The other end of torque tube member 27 has an annular and radially outwardly-extending reaction plate or reaction member 28. The reaction plate member 28 may be made integral with the torque tube member 27 or may be made as a separate annular piece and suitably connected to the torque tube or torque tube member 27. 
     Torque tube 27 has a plurality of circumferentially spaced splines, ribs, or spline members 30 which are axially extending. Wheel section 12 has a plurality of circumferentially spaced torque transmitting bars, torque bars or keys 35 connected thereto as at their inboard ends by spacer means to be described and at their outboard ends to the upper portion of web section 16 by seating in an annular recess 43 in such web section. The torque-transmitting bars or keys 35 may be secured to the web section 16 of wheel 11 by other suitable means to provide an integral connection there between. 
     Ribs or spline members 30 support an axially non-rotatable end disc or stator disc 38 and inner discs 39, 40 and 41. All of such nonrotatable discs 38, 39, 40 and 41 have slotted openings at circumferentially spaced locations on the inner periphery for captive engagement by the spline members 30, as is old and well-known in the art. An annular disc or annular braking element 42 is suitably connected to the reaction plate 28 and acts in concert with the stator discs 38, 39, 40 and 41 which discs (38, 39, 40, 41 and 42) constitute the stators for the friction brake 10. 
     A plurality of axially spaced discs (rotor discs) 44, 45, 46 and 47 interspaced or interleaved between the stator discs 38 through 42, have a plurality of circumferentially spaced openings along their outer periphery for engagement by the corresponding wheel keys 35, as is old and well known in the art, thereby forming the rotor discs for the friction brake 10. All of the non-rotatable discs (38, 39, 40, 41 and 42) and rotatable discs (44 through 47) may be made from a suitable brake material such as metal, steel or other wear-resistant material such as carbon for withstanding high temperatures and providing a heat sink. The number of discs may be varied, as is necessary for the application involved. The respective stator discs and rotor discs that have the circumferentially spaced openings on the inner and outer periphery may accommodate reinforcing inserts to provide reinforcement to the walls of such slotted openings and to enhance the life of such slots, as is old and well-known in the art. 
     The actuating mechanism for the brake includes a plurality of circumferentially spaced cylinders 50 suitable mounted on or connected to the flange 25. Within each of the cylinders 50 is a hydraulic piston, which is operative to move the stator disc 38 axially into and out of engagement with the rotatable disc 44, which in turn operates to have all of the brake disc to frictionally engage their radial surfaces and are resisted by the end stationary annular disc 42 and the reaction plate 28 on torque tube 27. During this period of brake disc engagement, the friction forces among all the rotatable and non-rotatable discs generate considerable heat energy within the discs and the adjacent structures. It is the frictional engagement of these stator and rotor discs which produces the braking action for the aircraft wheel. 
     A cylindrical heat shield 60 is located between the inner surface of wheel section 12 and the torque-transmitting bars or keys 35. As described above, each key 35 at its outboard end is connected to the web section 16 by seating in an annular recess 43. The inboard end of each key 35 and the adjacent portion of the heat shield 60 is secured to rim member 14 of web member 12 by a spacer 62 (FIG. 4). Spacer 62 is a rectangular shaped member being recessed on its upper and lower surfaces to present an upper flat surface 63 with a pair of spaced abutments or shoulders 64 and 65 and present a lower surface 66 with a lower pair of abutments or shoulders 67 and 68. The spaced shoulders 64 and 65 as seen in FIG. 3 provide a seat to captively secure the keys 35 and operate to transfer torque from the keys 35 to the rim member 14 (via a flanged portion 89 on the rim member 14). The lower shoulders 67 and 68 of spacer 62 as viewed in FIG. 3 create an air gap or air space 69 with respect to flange 89 of rim 14 which reduces the surface area for the transfer of heat energy by conduction. The reference to upper and lower as designated above with respect to upper flat surface 63 and lower surface 64 is with respect to FIG. 3 and it must be remembered that the rim is a circumferentially extending surface and that there are a plurality of circumferentially spaced keys relative to central axis of rotation of the rim member 14. Extending in an outboard direction or rearwardly as viewed in FIG. 4 from the rectangular shaped member of spacer 62 is a flanged portion 70 of substantially less thickness than the main body portion of spacer 62. In plan view, the flanged portion 70 is triangular in shape with a bore 71 therein adjacent to the apex 72. Spacer 62 has a bore 75 in the center portion thereof extending from the upper surface 63 to the lower surface 66. 
     The heat shield 60 has a plurality of circumferentially spaced square shaped apertures 80 along its inboard end. The entire periphery of the apertures 80 of the heat shield 60 is made from reinforced material and is designated 81 in FIGS. 2, 3, and 4. 
     The spacer 62 is secured to the heat shield 60 by having the rectangular shaped body portion of the spacer 62 enter the aperture 80 of the heat shield while the flanged portion 70 frictionally engages the heat shield and is attached thereto by a fastener 82 that extends through bore 71 and a bore 83 in heat shield 60 adjacent to aperture 80. The inboard end of torque bar 35 has an aperture 85 in alignment with bore 75 in spacer 62, and a bore 87 in the flanged portion 89 of rim member 14 such that a bolt 90 interconnects these members to firmly secure the heat shield 60 to the rim member of the wheel 11 and trap the heat shield As seen in FIG. 2, key 35 has a shoulder 73 which abuts a radial inner surface of the heat shield With a plurality of these circumferentially spaced shoulders 73 on keys 35, the heat shield 60 is trapped from a movement in a radial direction. This interconnection eliminates the numerous bolts that are ordinarily used to secure the heat shield to the wheel which thus eliminates the conduction heat energy path. The above described spacer bar 62 secures the shield in a fixed position both axially and in a tangential direction while the keys or torque bars 35 with its shoulders 73 locate the shield in a radial direction and provides multiple points of support around the full circumference of the shield. With the described fastening of the heat shield to the spacer 62 as by fastener (as by riveting), the heat shield 60 is easy to handle and facilitates the assembly of the brake and wheel assembly. 
     It will be apparent that although a specific embodiment of the invention has been described in detail, the invention is not limited to the specifically illustrated and described construction since variations may be made without departing from the principles of the invention.