Abstract:
A spline connector is provided which includes a first spline connector member. A second spline connector member is provided having backlash between spline teeth of the spline connector members. A spring is provided which biases the teeth of the spline connector members to engage with one another to counter separation resultant from negative torque oscillations.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. Provisional Application No. 60/809,781, filed May 30, 2006. 

   FIELD OF THE INVENTION 
   The present invention relates to spline type torsional connectors between driving and driven members. 
   BACKGROUND OF THE INVENTION 
   Spline connectors are typically used to transmit torque from a driving member to a concentric driven member. A spline connector typically will have small torsional force exchange members referred to as teeth or larger torsional force exchange members referred to as lugs. It is common to refer to both types of torsional force exchange members as “spline teeth”. Automotive vehicles typically have a spline connector between an output shaft of an engine and an input shaft to a transmission. During startup and shutdown of the engine, torsional vibrations of the engine can cause the spline connector to oscillate, contacting the front and back of the spline teeth in an alternating fashion. In effect, the torque from the engine output becomes negative for a brief instant. This speed and acceleration as to which the oscillation occurs causes impact on the back and front side of the spline teeth causing noise. The reason the impact happens is due to the backlash in the spline teeth design. The spline teeth can be made with no backlash, however it would mean great difficulty in assembling and disassembling the connector. The standard method to fix the oscillation problem is to put a damper between the engine output and the spline input to the transmission. The damper then reduces the amplitude of the negative torque on the spline connector. It is desirable to provide a method and apparatus to further minimize oscillations resulting from negative torque on a spline connector. 
   SUMMARY OF THE INVENTION 
   To meet the above noted desire of further minimizing oscillations resulting from negative torque in conjunction with a spline connector, the present invention is brought forth. The present invention provides a spline connector for a torsionally connected driving and driven machine. The spline connector includes driving and driven members. Backlash exists between teeth of the spline connector driving and driven members. A spring biases the teeth of the spline connector driving and driven members to engage with one another in a direction of contact to counteract negative torque of the driving member. The present invention can be used with or without a conventional damper. 
   Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
       FIG. 1A  is a schematic view of a spline connector; 
       FIG. 1B  is a schematic view of a spline connector, according to the present invention; 
       FIG. 2A  is a front plan view of a spline connector, according to the present invention; 
       FIG. 2B  is a sectional view taken along line  2 B- 2 B of  FIG. 2A ; 
       FIG. 2C  is a front plan view of a female portion of the spline connector shown in  FIG. 2A ; 
       FIG. 2D  is a sectional view taken along line  2 D- 2 D of  FIG. 2C ; 
       FIG. 2E  is a perspective view of the female portion of the spline connector shown in  FIG. 2C ; 
       FIG. 2F  is a sectional view taken along lines  2 F- 2 F of  FIG. 2A ; 
       FIG. 2G  is an enlarged view of a portion of the spline connector shown in  FIG. 2B  additionally illustrating portions of the operating environment of the connector; 
       FIG. 3A  is a perspective view of the spring plate utilized in the spline connector shown in  FIG. 2A ; 
       FIG. 3B  is a top plan view of the spring plate shown in  FIG. 3A ; 
       FIG. 3C  is a side elevational view of the spring plate shown in  FIG. 3A ; 
       FIG. 4  is a perspective view of portions of the spline connector shown in  FIG. 2A  looking towards a male member engine side of the connector with major portions of the female member (transmission side) of the connector being removed for clarity of illustration; 
       FIG. 5  is a perspective view illustrating placement of the spring plate upon the bolt heads of the male member of the connector with other portions of the male and female members being removed for clarity of illustration; 
       FIG. 6A  is a partial perspective view of an alternative embodiment spline connector of the present invention with portions of the male and female members of the connector being removed for clarity of illustration; 
       FIG. 6B  is a rear plan view of the connector of  FIG. 6   a;    
       FIG. 6C  is a sectional view of the connector shown in  FIG. 6B  with portions of the connector being removed for clarity of illustration; 
       FIG. 7  is a view similar to that of  FIG. 6  with portions of the spline connector being removed for clarity of illustration, illustrating placement of an adapter plate upon the male member of the coupler; 
       FIG. 8A  is a schematic sectional view of yet another embodiment of a spline connector according to the present invention; 
       FIG. 8B  is a schematic sectional view of a portion of the spline connector shown in  FIG. 8A  with the connector members being mated; 
       FIG. 8C  is a schematic operational view of a portion of the spline connector shown in  FIG. 8A  in a position subsequent to that of  FIG. 8B ; 
       FIG. 8D  is a schematic operational view of a portion of the spline connector shown in  FIG. 8A  wherein the engine and transmission are fully mated; 
       FIG. 9A  is a front plan view of yet another spline connector embodiment of the present invention; 
       FIG. 9B  is an enlargement of a portion of  FIG. 9A ; and 
       FIG. 9C  is an enlargement of a spring utilized in the spline connector shown in  FIG. 9A . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
     FIG. 1A  illustrates a spline type coupling or connector  2  having a male spline connector member  3  as a driving member and a female spline connector member  4  as a driven member. In an alternate spline connector application (not shown), the male member can be the driven member. In many applications the male member  3  can be integral with a fly wheel. The male member  3  has torsional force transmission members provided by spline teeth  5  (only two teeth shown) and the female spline connector member  4  has spline teeth  6  (only one tooth shown). Between the teeth  5 ,  6  there exists a slight clearance or gap commonly referred to as backlash  9  to ease assembly. Negative torque oscillations due to the reciprocal nature of the engine can cause the teeth  5 ,  6  to move back and forth with respect to each other contacting and causing noise. 
     FIG. 1B  illustrates the spline connector  7  of the present invention with a spring (not shown in  FIG. 1B ) providing a biasing force forcing engagement between a male tooth  14  with a female tooth  16  under momentary negative torque conditions. The spring preloads the tooth  14  to contact the tooth  16  in the direction of rotation  17 . Referring additionally to  FIGS. 2A-5 , male member  10  is integrated with a fly wheel  11 . The male member  10  is connected by a series of bolts  24  having heads  26  with a power source machine such as a motor or engine having an output shaft  28  with a flange  15 . A female member  12  is formed as a cylindrical drum with the spline teeth  16  being along its inner surface. The female member cylindrical drum  12  is welded to a plate  23  of a damper  13 . In the example shown, the plate  23  is torsionally connected with a clutch housing (not shown) by tabs  30 . The clutch housing is torsionally connected with inner and outer input shafts (not shown) of a transmission by splined hubs  20  and  22  ( FIG. 2G ). 
   The spline connector  7  also includes a spring plate  40 . The spring plate  40  on its outer diameter has a plurality of spline teeth  42 . The spline teeth  42  provide for the torsional connection of the spring plate  40  with the female member  12 . The spring plate  40  also has a central opening  44 . Central opening  44  is fitted over a central hub  46  that is connected with the female member  12 . The spring plate  40  has a plurality of cut-outs  48 . Formed from the cut-outs  48  are a plurality of spring fingers or tabs  50 . The spring tabs  50  have a contour  52  to allow the tabs to partially encircle the bolt heads  26 . The spring tabs  50  are also in a circumferential direction having a tapered surface  54 . Typically, the male and female members  10 ,  12  are not axially connected together. The locations of the male and female members  10 ,  12  are established by the axial location of the engine and transmission which is further established by the connection of the engine and transmission casings together. The mating of the transmission to the engine will cause the bolt heads  26  to engage the spring tabs  50  along the tapered surface  54  and thereby bias the bolt heads  26  in the direction  17  of rotation of the spline connector  7 . The spring plate  40  further has a locating tab  56 . The locating tab  56  extends along a flattened slot  58  provided between an interface of the male member  10  and female member  12 . The locating tab  56  ensures that the spring tabs  50  are in the proper position upon assembly or mating of the transmission with the engine. In operation the spring tab  50  pushes against the bolt heads  26  causing the female member  12  to react in a direction opposite of that of rotation  17 . The above noted reaction causes the teeth  16  to be brought into engagement with the teeth  14 . The biasing force of the spring tabs  50  urge the teeth  16  in a direction of contact to counteract possible negative torque. 
   Referring additionally to  FIGS. 6A-7 , an alternate embodiment spline torsional connector  107  of the present invention is provided. In  FIG. 6A  a radially inner portion of the male connector  110  is partially shown with the fly wheel removed for clarity of the illustration. The male connector  110  is connected to the engine output shaft by a series of bolts having bolt heads  26  as previously explained. The male connector  110  has a series of slots  112  in the cylinder which provides the male teeth  116 . A plurality of coil springs  102  are mounted on the bolt heads  26 . The springs  102  have legs  104 ,  106 . The coil springs encircle the bolt heads  26  and are carried by the male member  110 . The legs  106  are axially closest to the engine output shaft end extend through the slots  112 . 
     FIG. 7  illustrates a portion of an adapter plate  108 . The adapter plate  108  is joined to the female member (not shown) by fasteners or a spline connection in a manner as previously explained regarding spring plate  40 . The adapter plate  108  has a series of ramps  120  for engagement with the legs  106  of the spring  102 . As the transmission and engine are mated, the ramps  120  push against the spring legs  104 , torquing the springs  102  and causing the spring leg  106  to present a biasing force against the teeth  116  male member  110 . 
     FIGS. 8A-8D  ( FIG. 8A  being a partially sectioned view) provide a connector  207  having a U shaped flat plate spring  202  captured between two axially extending spline lugs  204 , 206  of the driving and driven members  208 , 210 . A pin  212  holds the spring  202  in a retracted or pre-compressed condition until the engine and transmission mate the connector  207 . Upon mating the lug  204  knocks the pin  212  into an aperture  214  partially releasing the spring  202 . The lug  204  has an extension  216  that radially retains the spring  202  in location. 
     FIGS. 9A-9C  provide a spline connector  307  with a self-releasing looped U shaped spring  302 . The spring is fitted over a special lug  304 . The spring  302  has an end with a clip  306  having a hook  308 . Before assembly of the connector  307  the hook is fitted within a window  310  of a leg  312  of the spring. Assembly of the driving and driven members  312 , 314  together causes the hook  308  to be knocked out of the window  310  thereby releasing the biasing force of the spring  302  which is captured between the lugs  316 , 318  of the driving and driven members. 
   The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.