Modular crankshaft

Abstract

In accordance with certain embodiments, a modular crankshaft features a connection system between modules that features opposed female receptacles. A pin having opposed beveled ends and hydraulic passages with it is inserted into the opposed receptacles. A pair of seals is disposed on the beveled ends and straddles a hydraulic fluid outlet. The crankshaft wall that defines each receptacle is designed to flex in response to applied hydraulic pressure between the seals on the tapered pin portion. A notch at the base of the receptacle in the crankshaft reduces stress concentration and enables the wall defining the crankshaft receptacle to come back when hydraulic pressure through the pin is removed. The opposed crankshaft receptacles are flanged to allow them to be pulled together over the pin. An interference fit results around the pin after the flanges are mated and the hydraulic pressure is removed.

1 . A system, comprising:
 a first shaft having a first annular wall disposed about a first receptacle; and   a connector disposed in the first receptacle, wherein the connector comprises a fluid passage extending to a first region adjacent the first annular wall, the first annular wall is elastically expandable in response to a first fluid pressure in the first region to reduce resistance during insertion of the connector into the first receptacle, and the first annular wall is contractible about the connector after removal of the first fluid pressure to create a first interference fit between the first shaft and the connector.   
     
     
         2 . The system of  claim 1 , comprising a second shaft having a second annular wall disposed about a second receptacle, wherein the first and second receptacles are disposed opposite from one another about the connector, the fluid passage of the connector extends to a second region adjacent the second annular wall, the second annular wall is elastically expandable in response to a second fluid pressure in the second region to reduce resistance during insertion of the connector into the second receptacle, and the second annular wall is contractible about the connector after removal of the second fluid pressure to create a second interference fit between the second shaft and the connector. 
     
     
         3 . The system of  claim 2 , wherein the first shaft comprises a first flange disposed about the first annular wall, the second shaft comprises a second flange disposed about the second annular wall, the first and second flanges are coupled together via a plurality of fasteners, and the plurality of fasteners are configured to move the first and second annular walls axially toward one another about the connector while the first and second fluid pressures cause elastic expansion of the first and second annular walls. 
     
     
         4 . The system of  claim 2 , wherein the connector comprises a first pair of annular seals disposed on opposite sides of the first region between the connector and the first annular wall, and the connector comprises a second pair of annular seals disposed on opposite sides of the second region between the connector and the second annular wall. 
     
     
         5 . The system of  claim 2 , wherein the fluid passage of the connector comprises a first outlet into the first region, the fluid passage comprises a second outlet into the second region, and the fluid passage comprises at least one inlet at an external intermediate region relative to the first and second receptacles. 
     
     
         6 . The system of  claim 5 , wherein the fluid passage of the connector comprises a central passage, a first passage, a second passage, and a third passage in fluid communication with one another, wherein the central passage is oriented along an axis of the connector, the first passage is oriented crosswise to the central passage and leads to the first outlet, the second passage is oriented crosswise to the central passage and leads to the second outlet, and the third passage is oriented crosswise to the central passage and leads to the at least one inlet. 
     
     
         7 . The system of  claim 1 , wherein the fluid passage of the connector comprises a first outlet into the first region, the fluid passage comprises a second outlet, and the fluid passage comprises at least one inlet at an external intermediate region relative to the first and second outlets. 
     
     
         8 . The system of  claim 1 , wherein the first annular wall comprises a reduced wall thickness at a first annular recess, and the first annular recess is configured to facilitate elastic expansion of the first annular wall. 
     
     
         9 . The system of  claim 1 , wherein fluid passage of the connector comprises a first outlet into the first region, and the connector comprises a first pair of annular seals disposed on opposite sides of the first outlet about the first region between the connector and the first annular wall. 
     
     
         10 . The system of  claim 1 , wherein the fluid passage of the connector comprises a central axial passage, a first radial passage, and a second radial passage in fluid communication with one another, wherein the first radial passage leads to a first outlet adjacent the first region, and the second radial passage leads to at least one inlet. 
     
     
         11 . The system of  claim 10 , wherein the fluid passage of the connector comprises a third radial passage in fluid communication with the central axial passage, the first radial passage, and the second radial passage, wherein the third radial passage leads to a second outlet, and the at least one inlet is disposed axially between the first and second outlets. 
     
     
         12 . A system, comprising:
 a male connector, comprising:
 a body having an annular exterior surface, a central axis, a first axial end, and a second axial end; 
 an inlet port in the annular exterior surface; 
 a first outlet port in the annular exterior surface; 
 a passage through the body in fluid communication with the inlet port and the first outlet port; and 
 a first male interference fit region along the annular exterior surface adjacent the first outlet port, wherein the male connector is configured to route a pressurized fluid through the inlet port to the first outlet port to cause elastic expansion of a first female connector during axial insertion of the male connector into the first female connector, and the male connector is configured to interference fit with the first female connector along the first male interference fit region after removal of the pressurized fluid and contraction of the first female connector about the male connector. 
   
     
     
         13 . The system of  claim 12 , wherein the annular exterior surface comprises a first conical surface converging toward the first axial end, and the first conical surface comprises the first inlet port. 
     
     
         14 . The system of  claim 12 , wherein the male connector comprises a first pair of annular seals disposed on the annular exterior surface on opposite axial sides of the first outlet port. 
     
     
         15 . The system of  claim 12 , wherein the first and second axial ends are closed to block fluid flow. 
     
     
         16 . The system of  claim 15 , wherein an interior of the body is solid except for the passage. 
     
     
         17 . The system of  claim 12 , wherein the passage comprises a lengthwise passage, a first passage crosswise to the lengthwise passage and leading to the first outlet port, and a second passage crosswise to the lengthwise passage and leading from the inlet port. 
     
     
         18 . The system of  claim 12 , comprising the first female connector having a first annular wall disposed about a first receptacle, wherein the first male interference fit region is disposed in the first receptacle. 
     
     
         19 . The system of  claim 18 , comprising the second female connector having a second annular wall disposed about a second receptacle, wherein the male connector comprises a second outlet port in the annular exterior surface in fluid communication with the passage, the male connector comprises a second male interference fit region along the annular exterior surface adjacent the second outlet port, the second male interference fit region is disposed in the second receptacle, the male connector is configured to route the pressurized fluid through the inlet port to the second outlet port to cause elastic expansion of the second female connector during axial insertion of the male connector into the second female connector, and the male connector is configured to interference fit with the second female connector along the second male interference fit region after removal of the pressurized fluid and contraction of the second female connector about the male connector. 
     
     
         20 . A method, comprising:
 routing a pressurized fluid through a passage in a male connector to a region within a female connector to create internal pressure;   elastically expanding the female connector in response to the internal pressure to increase clearance between the male connector and the female connector; and   contracting the female connector about the male connector in response to release of the internal pressure after insertion of the male connector into the female connector to create an interference fit between the male connector and the female connector.