Abstract:
A brake actuator includes a carrier ( 10 ) having a centerline ( 11 ), a periphery and a radial slot ( 16 ) in the periphery, and an EMA ( 20 ), including an electric motor ( 30 ) having a longitudinal centerline ( 31 ) and a ram ( 34 ) having a longitudinal centerline ( 35 ) operatively connected to the electric motor ( 30 ), where the electric motor ( 30 ) is designed to move the ram ( 34 ) in the direction of the ram longitudinal centerline ( 35 ), the EMA ( 20 ) being mounted on the carrier ( 10 ) in the slot ( 16 ) with the ram longitudinal centerline radially ( 35 ) inward of the periphery and the motor longitudinal centerline ( 31 ) radially outward of the periphery. Also the EMA ( 20 ) used in the brake actuator.

Description:
RELATED APPLICATIONS  
       [0001]     The present application claims the benefit of U.S. Provisional Patent Application No. 60/605,514, filed Aug. 31, 2004, the contents of which are hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention is directed toward a brake carrier and an electromechanical actuator (“EMA”) mountable thereon, and, more specifically, toward a brake carrier having a radial slot and an EMA mountable in the slot.  
       BACKGROUND OF THE INVENTION  
       [0003]     A brake disk stack comprises a plurality of stators disposed between a plurality of rotors. The rotors are connected to a vehicle wheel while the stators are fixed to, for example, a wheel support and brake. A brake employing such a disk stack acts by compressing the stack of rotors and stators to slow the rotors and the wheel attached to the rotors.  
         [0004]     Various actuators are known for compressing a disk stack, among them, an EMA.  FIG. 5  illustrates a braking system comprising a brake carrier  200  and a pressure plate  202  which forms part of a brake disk stack  204 . An EMA  206  is mounted on the side of brake carrier  200  opposite disk stack  204  so that a piston  208  of the EMA  206  extends through an opening  210  in the brake carrier  200 . Several openings  212 , illustrated in  FIG. 6 , are provided in brake carrier  200  for receiving fasteners  214 , such as screws or bolts, illustrated in  FIG. 5 .  
         [0005]     In operation, piston  208  moves toward the brake disk stack  204  and presses against the pressure plate  202  which in turn compresses the rotors and stators in a well-known manner. The reactive force of this movement is borne by the four fasteners  214  which prevent the EMA  206  from separating from the carrier plate  200  and which must therefore be sized to reliably withstand what can be significant stresses.  
         [0006]     To remove or attach EMA  206 , fasteners  214  are removed, and EMA  206  is moved axially with respect to the brake carrier  200  until piston  208  is clear of opening  210 . Because of the tight clearances in many devices employing such an arrangement, aircraft brakes, for example, it therefore is sometimes not possible to move EMA  206  axially a sufficient distance to allow the piston  208  to clear opening  210 . It is therefore sometimes necessary to remove part or all of the disk stack  204 , or other elements in the vicinity of the disk stack, to successfully remove the EMA  206 . This complicates the repair or replacement of EMA  206 .  
       SUMMARY OF THE INVENTION  
       [0007]     These problems and others are addressed by the present invention which comprises, in a first embodiment, an electromechanical actuator (EMA) that includes a housing having a first side and a second side and an opening through the second side into the housing. An electric motor is supported by the housing, and a ram having a longitudinal axis is mounted in the housing for linear movement through the opening and toward and away from the first side and is operatively connected to the electric motor. The housing has a first portion at the first side having a first width, a second portion at the second side having a second width greater than the first width and a transition wall connecting the first portion to the second portion.  
         [0008]     A further aspect of the invention comprises a brake actuator that includes a carrier having a centerline, a periphery and a radial slot in the periphery. An EMA includes an electric motor with a longitudinal centerline and a ram having a longitudinal centerline operatively connected to the electric motor. The electric motor is adapted to move the ram in the direction of the ram longitudinal centerline. The EMA is mounted on the carrier in the slot with the ram longitudinal centerline radially inward of the periphery and the motor longitudinal centerline radially outward of the periphery.  
         [0009]     Another aspect of the invention comprises a brake actuator that includes a carrier having a centerline, a periphery and a radial slot in the periphery and an EMA mounted in the slot. The EMA includes a housing having a first side and a second side and an opening through the second side into the housing. An electric motor is supported by the housing, and a ram is mounted in the housing and operatively connected to the electric motor for linear movement in a direction parallel to the carrier longitudinal centerline. The housing further includes a first portion at the first side having a first width and a second portion at the second side having a second width greater than the first width and a transition wall connecting the first portion to the second portion. The first portion passes through the slot and the transition wall engages the brake carrier and substantially prevents the second portion from moving axially toward the carrier. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     These aspects of the invention and others will be better understood after a reading of the following detailed description together with the following drawings wherein:  
         [0011]      FIG. 1  is an exploded perspective view of an EMA according to an embodiment of the present invention, a brake carrier having a radial slot, and a brake stack;  
         [0012]      FIG. 2  is a perspective view of the EMA of  FIG. 1  mounted on the brake carrier of  FIG. 1 ;  
         [0013]      FIG. 3  is a rear perspective view of the EMA of  FIG. 1 ;  
         [0014]      FIG. 4  is a front perspective view of the EMA of  FIG. 1 ;  
         [0015]      FIG. 5  illustrates a side elevational view of a conventional EMA mounted on a conventional carrier; and  
         [0016]      FIG. 6  is an end elevational view of the carrier of  FIG. 5 . 
     
    
     DETAILED DESCRIPTION  
       [0017]     Referring now to the drawings, wherein the showings are for purposes of illustrating a preferred embodiment of the invention only and not for the purpose of limiting same,  FIG. 1  illustrates a brake carrier  10 , having a centerline  11 , supporting a brake disk stack  12  that includes a plurality of rotors and stators and a pressure plate  14 . Brake carrier  10  includes a first side  15  facing pressure plate  14  and includes a radial slot  16  into carrier  10  through outer peripheral wall  18  for receiving a portion of an EMA  20 . Outer peripheral wall  18  also includes mounting holes  22 .  
         [0018]     EMA  20  is illustrated in association with carrier  10  in  FIGS. 1 and 2  and by itself in  FIGS. 3 and 4 . The primary functional elements of the EMA  20  are relatively standard and are not described in detail. These include a motor  30  having a centerline  31 , a ballscrew/ballnut assembly  32 , gears  33  operatively connecting the motor  30  to the ballnut/ballscrew assembly  32  and a ram or piston  34  movable in forward and reverse directions along a centerline  35 . These elements are contained within a housing  36 , and the position of ram  34  with respect to the housing is controlled by operating the motor  30  in forward or reverse directions.  
         [0019]     With reference to  FIGS. 3 and 4 , housing  36  has a first side  40  and a second side  42  that includes an opening  44  through which ram  34  moves relative to housing  36 . Opening  44  may be formed in second side  42  or in a guide sleeve  45  projecting from side  42  as best seen in  FIG. 4 . Housing  36  also includes a first portion  46  having a first width and a second portion  48  having a second width greater than the first width. First portion  46  has a first end  50  at first side  40  and a second end  52  adjacent a first end  54  of second portion  48 .  
         [0020]     Transition wall  56  connects the second end  52  of first portion  46  to the first end  54  of second portion  48 . Second portion  48  has a second end  58  at second side  42  of housing  36 . Transition wall  56  forms part of housing  36  and helps to enclose piston  34 ; transition wall  56  also serves as a reaction surface and is pressed against first side  15  of carrier  10  when piston  34  applies force to pressure plate  14  as described hereafter. Housing  36  is therefore sufficiently strong to withstand the force of piston  34  pressing transition wall  56  against the brake carrier and may include reinforcing elements  60  which may be, for example, part of the frame of the EMA  20 . Second portion  48  is enlarged relative to first portion  46  in order to provide a reaction surface  56 ; the size of second portion  46  is generally not needed to accommodate internal elements of EMA  20 . Housing  36  further includes first and second mounting tabs  62  that extend normal to the piston centerline  35 , and each tab  62  includes an opening  64  for receiving a fastener  66 .  
         [0021]     With reference to  FIGS. 1 and 2 , EMA  20  is installed on brake carrier  10  by aligning first portion  46  with slot  16  and moving EMA  20  radially with respect to brake carrier  10  until first portion  46  is received in slot  16  with transition wall  56  overlying and contacting first side  15  of brake carrier  10 . Fasteners  66  are placed through openings  64  in mounting tabs  62  and into openings  22  on outer peripheral wall  18  of brake carrier  10  to secure EMA  20  to carrier  10 .  
         [0022]     In this configuration, centerline  35  of ram  34  is located radially inwardly of peripheral outer wall  18 , and centerline  31  of motor  30  is located radially outwardly of outer peripheral wall  18 . In this manner, the size of slot  16  can be maintained at smaller size than would be required if the entire EMA  20  had to pass through carrier  10  thus potentially increasing the strength of carrier  10 . This arrangement also potentially allows for the use of a smaller brake carrier  10  than would otherwise be required. And, because a significant portion of housing  36  is located between first side  15  of brake carrier  10  and pressure plate  14 , a larger gap is present between carrier  10  and pressure plate  14  and thus more air can flow between carrier  10  and brake disk stack  12 . This potentially provides greater cooling to brake disk stack  12 .  
         [0023]     In operation, when a controller (not shown) causes motor  30  to drive ram  34  against pressure plate  14 , the reactive force presses transition wall  56  of housing  36  against first side  15  of brake carrier  10 . In this manner, substantially the entire reactive force is borne by the brake carrier  10  rather than by mounting screws as was the case in prior designs. Fasteners  66  that are strong enough to hold EMA  20  securely in place when the EMA  20  is not applying force to the brake disk stack  12  will therefore be strong enough to hold the EMA  20  in place when it is applying a force against brake disk stack  12  because they bear little, if any, of the reactive force.  
         [0024]     In addition to reducing the number and strength of fasteners needed for securing an EMA to a brake carrier, and therefore simplifying design and assembly, the present arrangement, in many environments, advantageously allows for the removal of EMA  20  from the brake carrier  10  without removing the brake carrier  10 , thus improving the line replaceability of the EMA  20 . This is because there is generally nothing limiting movement of the EMA  20  in a radial direction with respect to the brake carrier  10 . Furthermore, the radial insertion of EMA  20  into slot  16  in brake carrier  10  allows for easier electrical connections between these elements. Specifically, an electrical connector  68  on the underside of one of mounting tabs  62  is linearly insertable into a complimentary connector  70  on the outer peripheral wall  18  of brake carrier  10  when EMA  20  is inserted into slot  16 . This allows an electrical connection to the EMA to be made at the same time as the EMA is mounted and without any additional wiring or connection steps, thus further simplifying the installation and removal of the EMA  20 .  
         [0025]     The present invention has been described herein in terms of a preferred embodiment. Obvious modifications and additions to this embodiment will become apparent to those skilled in the relevant arts upon a reading of the foregoing description. It is intended that all such modifications and additions comprises a part of the present invention to the extent they fall within the scope of the several claims appended hereto.