Torque tubes and manufacturing methods thereof

Abstract

One aspect of the present disclosure relates to an apparatus comprising a first end fitting. The first end fitting comprises a tube engagement portion. The tube engagement portion comprises an outer coupling surface. The outer coupling surface comprises a first virtual cross-section. The first virtual cross-section comprises a first transverse inflection point. Each point along the first virtual cross-section has a first virtual tangent line coplanar with the first virtual cross-section.

What is claimed is: 
     
         1 . An apparatus ( 100 ), comprising a first end fitting ( 110   a ) that comprises a tube engagement portion ( 112 ) and wherein:
 the tube engagement portion ( 112 ) comprises an outer coupling surface ( 114 );   the outer coupling surface ( 114 ) has a first virtual cross-section ( 118 );   the first virtual cross-section ( 118 ) comprises a first transverse inflection point ( 119 ); and   each point along the first virtual cross-section ( 118 ) has a first virtual tangent line ( 120 ), coplanar with the first virtual cross-section ( 118 ).   
     
     
         2 . The apparatus ( 100 ) as in  claim 1 , further comprising a torque tube ( 130 ), coupled to the first end fitting ( 110   a ) and wherein:
 the torque tube ( 130 ) comprises an end fitting engagement portion ( 132 ), conformed to the tube engagement portion ( 112 ) of the first end fitting ( 110   a );   the end fitting engagement portion ( 132 ) comprises an inner coupling surface ( 134 );   the inner coupling surface ( 134 ) has a second virtual cross-section ( 138 ), coplanar with and complementary to the first virtual cross-section ( 118 );   the second virtual cross-section ( 138 ) comprises a second transverse inflection point ( 142 ); and   each point along the second virtual cross-section ( 138 ) has a second virtual tangent line ( 143 ) coplanar with the second virtual cross-section ( 138 ).   
     
     
         3 . The apparatus ( 100 ) as in  claim 2 , wherein:
 the end fitting engagement portion ( 132 ) further comprises an outer surface ( 154 );   the outer surface ( 154 ) has a third virtual cross-section ( 156 ), coplanar with the second virtual cross-section ( 138 );   the third virtual cross-section ( 156 ) comprises a third transverse inflection point ( 158 ); and   each point along the third virtual cross-section ( 156 ) has a third virtual tangent line ( 160 ), coplanar with the third virtual cross-section ( 156 ).   
     
     
         4 . The apparatus ( 100 ) as in  claim 2 , wherein the torque tube ( 130 ) comprises titanium. 
     
     
         5 . The apparatus ( 100 ) as in  claim 2 , wherein the torque tube ( 130 ) has a wall thickness between about 0.04 and about 0.06 inches. 
     
     
         6 . The apparatus ( 100 ) as in  claim 1 , wherein:
 the first end fitting ( 110   a ) further comprises a connector portion ( 111 ), adjacent the tube engagement portion ( 112 ), and the connector portion ( 111 ) comprises means ( 113 ) for connecting the apparatus ( 100 ) to one of a drive unit or a driven unit.   
     
     
         7 . The apparatus ( 100 ) as in  claim 1 , wherein:
 the outer coupling surface ( 114 ) of the tube engagement portion ( 112 ) comprises a first virtual longitudinal section ( 121 );   the first virtual longitudinal section ( 121 ) comprises a first longitudinal inflection point ( 122 ); and   each point along the first virtual longitudinal section ( 121 ) has a fourth virtual tangent line ( 123 ), coplanar with the first virtual longitudinal section ( 121 ).   
     
     
         8 . The apparatus ( 100 ) as in  claim 7 , further comprising a torque tube ( 130 ), coupled to the first end fitting ( 110   a ) and wherein:
 the torque tube ( 130 ) comprises an end fitting engagement portion ( 132 ), conformed to the tube engagement portion ( 112 ) of the first end fitting ( 110   a );   the end fitting engagement portion ( 132 ) comprises an inner coupling surface ( 134 );
 the inner coupling surface ( 134 ) has a second virtual longitudinal section ( 144 ), coplanar with and complementary to the first virtual longitudinal section ( 121 ); 
 the second virtual longitudinal section ( 144 ) comprises a second longitudinal inflection point ( 145 ); and 
 each point along the second virtual longitudinal section ( 144 ) has a fifth virtual tangent line ( 146 ) coplanar with the second virtual longitudinal section ( 144 ). 
   
     
     
         9 . The apparatus ( 100 ) as in  claim 8 , wherein:
 the end fitting engagement portion ( 132 ) further comprises an outer surface ( 154 );   the outer surface ( 154 ) comprises a third virtual longitudinal section ( 162 ), coplanar with the second virtual longitudinal section ( 144 );   the third virtual longitudinal section ( 162 ) comprises a third longitudinal inflection point ( 164 ); and   each point along the third virtual longitudinal section ( 162 ) has a sixth virtual tangent line ( 166 ), coplanar with the third virtual longitudinal section ( 162 ).   
     
     
         10 . A vehicle ( 104 ) comprising:
 an apparatus ( 100 ) comprising:
 a first end fitting ( 110   a ), comprising a tube engagement portion ( 112 ), wherein:
 the tube engagement portion ( 112 ) comprises an outer coupling surface ( 114 ), 
 all contours of the outer coupling surface ( 114 ) are smooth, and 
 the outer coupling surface ( 114 ) comprises at least one first concavity ( 124 ) and at least one first convexity ( 126 ); 
 
 a second end fitting ( 110   b ); and 
 a torque tube ( 130 ), comprising a first end ( 131   a ) and a second end ( 131   b ); and 
 wherein:
 the first end ( 131   a ) of the torque tube ( 130 ) is coupled to the first end fitting ( 110   a ); 
 the second end ( 131   b ) of the torque tube ( 130 ) is coupled to the second end fitting; 
 the first end ( 131   a ) of the torque tube ( 130 ) comprises an end fitting engagement portion ( 132 ); 
 the end fitting engagement portion ( 132 ) comprises an inner coupling surface ( 134 ) conformed to the outer coupling surface ( 114 ) of the tube engagement portion ( 112 ) of the first end fitting ( 110   a ); 
 all contours of the inner coupling surface ( 134 ) are smooth, 
 the inner coupling surface ( 134 ) comprises at least one second convexity ( 174 ), complementary to the at least one first concavity ( 124 ) of the outer coupling surface ( 114 ) of the tube engagement portion ( 112 ), and 
 the inner coupling surface ( 134 ) comprises at least one second concavity ( 170 ), complementary to the at least one first convexity ( 126 ) of the outer coupling surface ( 114 ) of the tube engagement portion ( 112 ); 
 
   a drive unit ( 102 ), coupled to the first end fitting ( 110   a ); and   a driven unit ( 103 ), coupled to the second end fitting.   
     
     
         11 . The vehicle ( 104 ) as in  claim 10 , wherein:
 the end fitting engagement portion ( 132 ) of the torque tube ( 130 ) further comprises an outer surface ( 154 );   the outer surface ( 154 ) comprises at least one third concavity ( 180 ) and at least one third convexity ( 184 ); and
 all contours of the outer surface ( 154 ) are smooth. 
   
     
     
         12 . The vehicle ( 104 ) as in  claim 11 , wherein the outer surface ( 154 ) of the end fitting engagement portion ( 132 ) of the torque tube ( 130 ) further comprises at least one third flat ( 182 ). 
     
     
         13 . The vehicle ( 104 ) as in  claim 11 , wherein the at least one third concavity ( 180 ) comprises a smallest radius of curvature of between 0.125 and 0.25 inches. 
     
     
         14 . The vehicle ( 104 ) as in  claim 10 , wherein the outer coupling surface ( 114 ) further comprises at least one first flat ( 125 ). 
     
     
         15 . The vehicle ( 104 ) as in  claim 14 , wherein:
 the inner coupling surface ( 134 ) further comprises at least one second flat ( 172 ); and
 the at least one second flat ( 172 ) is complementary to the at least one first flat ( 125 ). 
   
     
     
         16 . The vehicle ( 104 ) as in  claim 14 , wherein:
 the inner coupling surface ( 134 ) further comprises at least one second flat ( 172 ); and
 each of the at least one second flat ( 172 ) is complementary to a different one of the at least one first flat ( 125 ). 
   
     
     
         17 . The vehicle ( 104 ) as in  claim 10 , wherein the inner coupling surface ( 134 ) further comprises at least one second flat ( 172 ). 
     
     
         18 . The vehicle ( 104 ) as in  claim 17 , wherein the at least one second flat ( 172 ) is located between the at least one second convexity ( 174 ) and the at least one second concavity ( 170 ). 
     
     
         19 . The vehicle ( 104 ) as in  claim 17 , wherein one of the at least one second flat ( 172 ) is located between two of the at least one second convexity ( 174 ). 
     
     
         20 . The vehicle ( 104 ) as in  claim 17 , wherein one of the at least one second flat ( 172 ) is located between two of the at least one second concavity ( 170 ).