Patent Publication Number: US-2010116579-A1

Title: Bent axis hydromodule with bolt on trunnion bearing carriers

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to bent axis hydromodules. More specifically, this invention relates to attachment of a bearing carrier to the frame of a bent axis hydromodule. 
     Bent axis hydromodules are well known in the art. FIGS. 1 and 2 show prior art versions of bent axis hydromodules wherein FIG. 2 is shown in the U.S. Ser. No. 12/188,358 specification of which is incorporated herein. Current hydromodule designs use screws to react to trunnion forces in the shear direction as is shown in FIG. 1. These screw joints rely on friction in the shear plane to react to these trunnion forces. By relying on friction, only a small percentage of the screws preload force is available to react to trunnion forces. Consequently, a large number of screws have to be used in order to provide a bearing carrier that is able to handle the loads that result from the trunnion forces. As many as 21 screws can be used in a typical application in order to provide the desired force needed. 
     Therefore, a principal object of the present invention is to reduce the amount of parts of a bent axis hydromodule. 
     Yet another object of the present invention is to reduce the complexity of a bent axis hydromodule. 
     Another object of the present invention is to facilitate the assembly of a bent axis hydromodule while reducing package size and cost. 
     These and other objects, features, or advantages of the present invention will become apparent from the specification and claims. 
     BRIEF SUMMARY OF THE INVENTION 
     A bent axis hydromodule that has a frame and a yoke with trunnions that are pivotably received by the frame for rotation of the yoke about a trunnion axis. A bearing carrier receives the trunnion and is secured to the frame by at least one fastening element that extends axially perpendicular to the trunnion axis. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a prior art bent axis hydromodule; 
         FIG. 2  is a perspective view of a prior art bent axis hydromodule; 
         FIG. 3  is an exploded partial perspective view of a bent axis hydromodule; 
         FIG. 4  is an exploded partial perspective view of a bent axis hydromodule; and 
         FIG. 5  is an exploded partial perspective view of a bent axis hydromodule. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 2  shows a typical bent axis hydromodule  10 . The hydromodule  10  is comprised of a frame  12  upon which a yoke  14  and rotating kits  16  having rotating kit shafts (not shown) are mounted. 
     The frame  12  includes opening  22  disposed therein for receiving the rotating kits  16  and receptacles  24  for receiving the yoke  14 . 
     The yoke  14  as shown in  FIG. 2  is a dual yoke with first and second yokes  30  and  32  being fluidly connected to one another. Each yoke  30  and  32  has internal porting (not shown) wherein the first and second rotating kit fluidly connection to one another. The yoke  14  additionally has trunnions, or journals  38 , that are received by the receptacles  24  of frame  12  and bearing carrier  44  so that the yoke rotates about trunnion axis  40 . As the yoke  14  rotates about the trunnion axis  40  volumetric displacement is altered thus affecting the operation of the rotating kits  16 . 
     While  FIG. 2  shows a bent axis dual yoke hydromodule the present application is directed toward any type of bent axis hydromodule. Thus, single yoke bent axis hydromodules are also envisioned for the present invention. Specifically, any bent axis type hydromodule or swashplate that utilizes trunnions  38  to provide a swinging, pivoting, or rotating type movement to actuate yokes, is contemplated without falling outside of the present disclosure. 
       FIGS. 3-5  show a bearing carrier assembly  42 . The bearing carrier assembly  42  includes the frame  12  and a bearing carrier  44 . As shown in the figures the frame  12  has been modified to provide a plurality of openings  46  disposed therethrough for receiving a fastening element  48 . The openings  46  are disposed through the width of the frame  12  extending parallel to opening  22 . Additionally, adjacent the receptacle  24  is a female groove  50  for receiving the bearing carrier  44 . The fastening element  48  in a preferred embodiment is a bolt that can be threaded into either frame  12  or bearing carrier  44 ; however, could be any other fastening element such as a screw or the like. 
     The bearing carrier  44  extends from a first end  52  to a second end  54  and has a body  56  therebetween. The body  56  includes a cavity  57  that receives the trunnion bearing at an end of the trunnion  38 . At the first end  52  is a first flange  58  that has openings  46  disposed therethrough. The second end  54  similarly has a second flange  60  that also contains openings  61  disposed therethrough. In the embodiment as shown in  FIG. 3  the first and second flanges  58  and  60  are offset. When in alignment the openings  61  of the first and second flanges  52  and  54  align with the openings  46  of the frame  12  wherein the fastening element  48  can be disposed through the openings  46  and  61  to secure the bearing carrier  44  to the frame  12 . 
     Typically, to withstand the forces applied by the trunnion  38  on the bearing carrier  44  only four fastening elements  48  are required for each trunnion. Thus, only eight fastening elements  48  are required per hydromodule  10 . Specifically, because the fastening elements  48  extend axially perpendicular to the trunnion axis  40 , the fastening element  48  preload force is in the same direction as the primary loading on the joint. As a result, the total number of fastening elements  48  is drastically reduced wherein typically the prior art design shown in  FIG. 1  requires 21 fastening elements. One skilled in the art will understand that when referring to the axial direction that the fastening element  48  in the figures extends axially along its length that is in greater size than the radial extension of the fastening element  48 . This axial extension, or plane, is a plane that is perpendicular to the trunnion axis  40  wherein in the prior art design seen in  FIG. 1  this axial plane was parallel to the trunnion  38 . 
     In operation, the interior cavity  57  receives the trunnion bearing. Once in place the openings  46  of the frame  12  align with the openings  61  of the bearing carrier  44  so that fastening elements  48  are disposed through both of the openings  46  and  59  to secure the bearing carrier  44  to the frame  12 . 
     By placing the fastening element  48  axially perpendicular to the trunnion axis  40  the screw preload force is in the same direction as the primary loading in the joint making it more efficient use of the fastening elements  48 . Consequently, the number of fastening elements  48  required is greatly reduced causing a reduced part count for the hydromodule. Additionally, by having this reduced part count there is reduced complexity, package size, and cost; all advantages provided over prior art bent axis hydromodules. Also, by reducing parts the assembly process is facilitated over that shown in the prior art. Consequently, at the very least all of the stated objectives have been met. 
     It will be appreciated by those skilled in the art that other various modifications could be made to the device without departing from the spirit and scope of this invention. All such modifications and changes fall within the scope of the claims and are intended to be covered thereby.