Patent Abstract:
A chip or debris trap or collector retains chips, fragments and other debris generated when a serrated or splined, press fit connection is assembled between a shaft and another component such as a housing, gear, pulley or bearing. The chip collector includes a circumferential channel or groove disposed about the shaft adjacent the ring of serrations or male splines and an adjacent circumferential flange. An optional second channel or groove resides in the other component. As the shaft and the component are assembled, chips, fragments or other debris generated by the interference fit and axial sliding assembly of the components are collected in the channel or channels and retained there as the shaft fully seats within the other component.

Full Description:
FIELD 
       [0001]    The present disclosure relates to a debris collector of serrated shafts and more particularly to a collector for chips and debris resulting from press fitting a serrated or splined shaft into a complementary component. 
       BACKGROUND 
       [0002]    The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
         [0003]    Many powerline components such as shafts, gears, pulleys, bearings and the like are assembly by press fitting one component of the other. One of several methods may be involved: heating the outer component to slightly expand it while positioning it on the inner component and allowing it to cool or, given a very small interference fit, simply forcing one component onto or into the other. Frequently the site of the press fit will include male serrations which fit within a smooth bore or complementary male and female splines which both greatly increase the torque carrying capability of the connection. 
         [0004]    While a serrated or splined, press fit connection does provide increased torque carrying capability relative to a smooth press fit connection, there is often an unwanted consequence of utilizing such mating surfaces and that is the generation of fragments, chips and debris from one or both of the components. Such foreign material may fall away from the completed connection immediately, it may remained attached momentarily or for a lengthy period of time or it may be so secure that it remains with the connected components forever. 
         [0005]    The last situation (permanent attachment), though not desirable, is generally not of concern but fragments, chips and debris generated by the connection process that fall away immediately or during operation are. Those which fall away or dislodge immediately should be removed by a cleaning process as they may otherwise remain with the assembled components until places in operation. The same is true of debris which remains initially attached but falls away in service. Ensuring the removal of all debris by a cleaning process is generally time consuming and, given the complexity of many components which include passageways, channels, blind openings and the like, may not always achieve the desired result. Clearly metal fragments, chips or debris circulating within, for example, the lubrication system of a device such as an internal combustion engine, manual or automatic transmission, transfer case or differential are to be avoided. 
         [0006]    The present invention is directed to a means for trapping metal fragments, chips and debris in a serrated or splined, press fit connection between a shaft and a housing, a gear, a pulley, a bearing or other component. 
       SUMMARY 
       [0007]    The present invention provides a chip or debris trap or collecter which retains metal chips, fragments and other debris generated when a serrated or splined, press fit connection is assembled between a shaft and another component such as a housing, a gear, a pulley or a bearing. The chip trap or collector includes a circumferential channel or groove disposed about the shaft adjacent the ring of serrations or male splines and an adjacent circumferential flange. In the direction of assembly, the flange is first encountered, then the channel or groove and then the serrations or splines. The outer component, that is, the housing, the gear, etc., in addition to a smooth bore, optionally includes a second channel or groove that generally axially aligns with the channel or groove of the shaft when the two components are fully assembled. During the assembly process, any fragments, chips or other debris generated by the interference fit and axial sliding assembly of the components are driven into the channels or grooves and retained there when the outer component is fully seated on the shaft. 
         [0008]    Thus it is an aspect of the present invention to provide a shaft intended for press fit assembly having a chip or debris collecting and retaining feature. 
         [0009]    It is a further aspect of the present invention to provide a shaft having serrations and a chip or debris retaining feature adjacent the serrations. 
         [0010]    It is a still further aspect of the present invention to provide a shaft having serrations, a chip or debris collecting channel adjacent the serrations and a chip retaining flange adjacent the channel. 
         [0011]    It is a still further aspect of the present invention to provide a shaft having serrations, a chip or debris retaining channel adjacent the serrations and a chip or debris retaining channel in the mating component. 
         [0012]    It is a still further aspect of the present invention to provide a shaft having a male spline set, a chip or debris retaining channel or groove adjacent the spline set and a circumferential flange adjacent the groove. 
         [0013]    It is a still further aspect of the present invention to provide a shaft having a male spline set, a chip or debris retaining circumferential channel or groove adjacent the spline set and a debris retaining channel or groove in the mating component. 
         [0014]    It is a still further aspect of the present invention to provide a shaft having serrations and a chip or debris retaining channel or groove adjacent the serrations that is aligned with a chip retaining channel or groove in a component such as a housing, gear or pulley when the component is fully assembled on the shaft. 
         [0015]    Further aspects, advantages and areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0016]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0017]      FIG. 1  is a side elevational view of a shaft and housing assembly which incorporates the present invention; 
           [0018]      FIG. 2  is a perspective view of the shaft according to the present invention; 
           [0019]      FIG. 3  is an fragmentary, full sectional view of a portion of the shaft and housing illustrated in  FIG. 1  according to the present invention at the beginning of the assembly process; 
           [0020]      FIG. 4  is a fragmentary, half sectional view of a portion of the shaft and housing illustrated in  FIG. 1  according to the present invention during the assembly process; and 
           [0021]      FIG. 5  is an enlarged, fragmentary, half sectional view of a portion of the shaft and housing illustrated in  FIG. 1  according to the present invention at the completion of the assembly process. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
         [0023]    With reference to  FIGS. 1 ,  2  and  3 , a housing which may be, for example, a rotating component of an automatic transmission or other power carrying or delivering device, is illustrated and generally designated by the reference number  10 . It will be appreciated that the housing  10  is exemplary and illustrative only and that other components such as gears, pulleys, bearings and the like may be utilized in its place. The housing  10  is circular, is preferably fabricated or a relatively lightweight and soft material such as aluminum and includes various radial and oblique passageways  12  and external features such as splines or gear teeth (not illustrated) and an outer, cylindrical wall  14  which may be received within associated components (also not illustrated). The housing  10  may also include an annular elastomeric seal  16  which engages and seals off a central region  18  of the housing  10 . 
         [0024]    Secured to the housing  10  by an interference press fit is a shaft  20 . The shaft  20  may be solid or hollow as illustrated, is preferably fabricated of a relatively hard and strong material such as steel and rotationally couples the housing  10  to other components (not illustrated). As such, the shaft  20  may include, for example, a plurality of radial lubrication ports  22  at one end and a male spline set  24  at the other which drivingly engages a complementary female spline set (not illustrated). 
         [0025]    It will be appreciated that the rotating housing  10  and the shaft  20  may typically be disposed with a housing of an automatic transmission (not illustrated) or similar fluid lubricated device and will therefore be exposed to and surrounded by a flow of transmission fluid or other lubricating oil. It is this environment in which metal fragments, chips and debris resulting from the press fit assembly process, if not contained or previously removed, may and generally will be flushed out of the shaft  20  during operation and be suspended and circulate with the transmission fluid throughout the transmission and possibly interfere with its operation. 
         [0026]    As illustrated in  FIGS. 2 and 3 , the shaft  20  includes an axially and circumferentially extending region of serrations or splines  26 . The serrations  26  may be any axially oriented, random or regular upsets such as alternating projections and grooves, ridges, teeth and the like that will engage, upset, abrade and grip a mating component such as the housing  10 . Immediately adjacent the serrations or splines  26 , toward the lubrication ports  22 , is a first circumferential fragment, chip or debris collecting and retaining channel or groove  30 . And adjacent the first chip collecting groove  30  (on the side opposite the serrations or splines  26 ) is a circumferential flange  32 . It will be appreciated that the circumferential flange  32  axially defines one side of the first chip collecting groove  30  and that the region of serrations or splines  26  defines the other. 
         [0027]    The shaft  20  terminates in a reduced diameter region  34  which includes the lubrication ports  22  and defines a diameter that is slightly larger than a cylindrical region  42  of reduced diameter of the housing  10 , resulting in an interference press fit between the reduced diameter region  34  of the shaft  20  and the cylindrical region  42  of reduced diameter of the housing  10  when they are assembled. 
         [0028]    The housing  10  also includes a smooth cylindrical bore  44  that has an inside diameter smaller than the nominal outside diameter of the serrations or splines  26  such that there is an upsetting and abrading interference fit between the serrations or splines  26  and the cylindrical bore  44  of the housing  10 . The outside diameter of the circumferential flange  32  is smaller than the nominal outside diameter of the serrations or splines  26  and is substantially equal to the diameter of the smooth cylindrical bore  44  such that there is a tight clearance fit therebetween. 
         [0029]    Proximate the end of the smooth bore  44  of the housing  10  is a second circumferential fragment, chip or debris collecting and retaining channel or groove  50 . It should be appreciated that the second circumferential fragment, chip or debris collecting and retaining channel or groove  50  is optional. While it does increase the total volume available to collect and retain fragments, chips and other debris, it has generally been found that a single channel or groove such as the groove  30  in the shaft  20  suffices for this purpose. 
         [0030]    At the end of the smooth cylindrical bore  44 , adjacent the second chip collecting groove  50  is a shoulder  52  which transitions from the region of reduced diameter  42  to the larger diameter of the smooth cylindrical bore  44 . It will be appreciated that when the housing  10  is fully assembled to the shaft  20 , the first and the second chip collecting grooves  30  and  50  align or substantially align and the circumferential flange  32  on the shaft  20  abuts the shoulder  52  of the housing  10 . 
         [0031]      FIGS. 3 ,  4  and  5 , illustrate steps in the assembly process with the housing  10  (or other component) and the shaft  20 . In  FIG. 3 , assembly is just beginning as the reduced diameter region  34  of the shaft  20  is aligned with, piloted on and sliding into the cylindrical region of reduced diameter  42  of the housing  10 . The serrations or splines  26  on the shaft  20  have not yet engaged the smooth bore  44  of the housing  10 . 
         [0032]    In  FIG. 4 , assembly is continuing as the shaft  20  has translated further into the cylindrical region of reduced diameter  42  of the housing  10 . Note that the circumferential flange  32  has engaged the smooth bore  44  of the housing  10  with a tight clearance fit before the serrations or splines  26  engage the smooth bore  40 , thereby effectively closing off the forward edge of the first chip collecting groove  30  before any such fragments, chips or debris are generated. In this regard, it should be appreciated that it is the leading edge of the serrations or splines  26  (adjacent the circumferential groove  30 ) that generates the fragments, chips and debris during assembly. Thus any fragments, chips or debris are prevented from moving beyond the circumferential flange  32  (to the left in  FIG. 4 ) and contaminating or becoming lodged in, for example, the lubrication ports  22 . 
         [0033]    In  FIG. 5 , the shaft  20  is fully seated within and secured to the housing  10 . At the outset, note that an upset, abraded, interference fit has been created between the serrations or splines  26  of the shaft  20  and the smooth bore  44  of the housing  10 . In this regard, also note the presence of metal chips or debris  60  within the first and the second chip collecting grooves  30  and  50  that were generated as the serrations or splines  26  upset, abraded and removed material from the smooth cylindrical bore  44  of the housing  10 . Next, note that the first chip collecting groove  30  and the optional second chip collecting groove  50  are axially aligned, thereby creating a relatively large circumferential channel about the shaft  20  in which metal fragments, chips and debris  60  from the assembly process may collect and be permanently retained. Finally, note that the flange  32  of the shaft  20  is abutting and fully seated against the shoulder  52  of the housing  10 . These features and this action ensures (1) that the shaft  20  is positively and fully seated within the housing  10  and (2) that the first and the second chip collecting grooves  30  and  50  are fully or substantially fully aligned. Finally, note that in the fully assembled position, some of the lubrication ports  22  of the shaft  20  align with the radial passageways  12  in the housing  10  thereby facilitating fluid flow from the interior of the shaft  20  to components within the housing  10 . 
         [0034]    The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be, and are, within the scope of the invention and claims. Such variations are not to be regarded as a departure from the spirit and scope of the invention.

Technology Classification (CPC): 5