PDM transmission with sliding contact between convex shaft pins and concave bearings surfaces
Unlaminated bearings (or Torque Transfer Elements, or TTEs) are disposed to slide and displace within pockets (or “housing cavity receptacles”) provided in the internal periphery of a housing in which an articulating shaft is received. As the shaft “tilts” about its untilted axial centerline during misaligned rotation, convex curved bearing surfaces on shaft pins slidably rotate against corresponding concave curved bearings surfaces on the T as received in the housing cavity receptacles. Further, substantially flat surfaces on the TTEs are disposed to slidably displace against corresponding bearing surfaces on the housing cavity receptacles as the shaft tilts and the convex curved bearing surfaces on the shaft pins slidably rotate against the concave curved bearing surfaces on the TTEs. The sliding displacement of TTEs with respect to the housing cavity receptacles during articulated rotation is in a direction generally parallel to the shaft's untilted axial centerline.
1. A torque transmission, comprising:
an input shaft adapter having first and second ends, the first end of the input shaft adapter configured to mate with an input shaft, the second end of the input shaft adapter providing a plurality of pins disposed on an outer surface of the input shaft adapter, each pin providing a curved pin portion;
an output shaft adapter having first and second ends, the second end of the output shaft adapter configured to mate with an output shaft, the first end of the output shaft adapter providing a recess formed therein;
a plurality of notches formed in a recess periphery of the recess, one notch for each pin disposed on the input shaft adapter, wherein the recess is shaped and sized to receive the second end of the input shaft adapter such that when the second end of the input shaft adapter is received inside the recess, each pin on the input shaft adapter is received into a corresponding notch on the recess;
a plurality of bearings, a curved portion provided on each bearing; and
wherein one bearing is interposed between one pin and one corresponding notch when the pins are received into their corresponding notches, such that the curved portion of the bearing contacts the curved pin portion; and
wherein selected bearings each further comprise a flat portion, each flat portion contacting the notch when the pins are received into their corresponding notches.
2. The torque transmission of claim 1 , in which selected ones of the curved portions of the bearings and the flat portions of the bearings include a laminate.
3. The torque transmission of claim 2 , in which the laminate comprises metal and elastomer layers.
4. The torque transmission of claim 1 , further comprising:
a boot retainer, the boot retainer having first and second boot retainer ends; and
an outer input shaft adapter periphery on the second end of the input shaft adapter and an outer output shaft adapter periphery on the first end of the output shaft adapter;
wherein, when the second end of the input shaft adapter is received inside the recess, the boot retainer is received over the input shaft adapter and the output shaft adapter such that the first end of the boot retainer is affixed to the outer input shaft adapter periphery and the second end of the boot retainer is affixed to the outer output shaft adapter periphery.
5. The torque transmission of claim 1 , further comprising:
an outer output shaft adapter periphery on the first end of the output shaft adapter;
a fill port connecting the outer output shaft adapter periphery to the recess; and
an evacuate port connecting the outer output shaft adapter periphery to the recess.
6. The torque transmission of claim 1 , in which selected pins each have a midpoint, and in which the curved pin portions on said selected pins each have a radius whose centerpoint coincides with the midpoint.
7. The torque transmission of claim 1 , in which each pin has a maximum pin nose diameter, and in which selected pin nose diameters are on a locus that coincides with an outer diameter of the output shaft.
8. An articulated transmission disposed to transmit torque via misaligned rotation, the transmission comprising:
a shaft having an axial shaft centerline about which the shaft is disposed to rotate;
a plurality of shaft pins, each shaft pin extending radially from the shaft centerline, each shaft pin further providing a convex shaft pin bearing surface thereon;
a generally cylindrical housing having an axial housing centerline about which the housing is disposed to rotate, the housing having a plurality of housing cavity receptacles formed therein, each housing cavity receptacle for receiving a corresponding shaft pin; and
a plurality of torque transfer elements (TTEs), each TTE providing a concave TTE pin bearing surface and a TTE housing bearing surface;
wherein each housing cavity receptacle provides a housing bearing surface;
wherein a shaft pin and a TTE are received into each housing cavity receptacle such that within each housing cavity receptacle, the convex shaft pin bearing surface is received onto the concave TTE pin bearing surface and the TTE housing bearing surface opposes the housing bearing surface;
wherein, responsive to misaligned rotation of the shaft centerline with respect to the housing centerline and regardless of angular deflection of the shaft centerline with respect to the housing centerline experienced within each housing receptacle during an articulated revolution of the shaft: (1) the concave TTE pin bearing surfaces are free to slidably displace relative to the convex shaft pin bearing surfaces; and (2) the TTE housing bearing surfaces are free to slidably displace against corresponding housing bearing surfaces.
9. The transmission of claim 8 , in which the TTEs float at least generally parallel to an untilted shaft centerline when the TTE housing bearing surfaces slidably displace against corresponding housing bearing surfaces.
10. The transmission of claim 8 , in which:
each shaft pin further provides a shaft backlash surface; and
each housing cavity receptacle further provides a housing backlash surface to oppose a corresponding shaft backlash surface;
wherein the transmission further includes a backlash energizer assembly interposed between at least one opposing shaft backlash surface and housing backlash surface.
11. The transmission of claim 10 , in which the backlash energizer assembly includes a puck.
12. The transmission of claim 11 , in which the puck includes a laminate of metal and elastomer layers.
13. The transmission of claim 11 , in which the puck separates a set screw and a Belleville washer.
14. The transmission of claim 10 , in which the backlash energizer assembly includes a plate, and in which the plate separates a set screw and a ball.
15. The transmission of claim 8 , in which selected ones of the TTE pin bearing surfaces and the TTE housing bearing surfaces include a laminate.
16. The transmission of claim 15 , in which the laminate comprises metal and elastomer layers.
17. The transmission of claim 8 , in which selected TTE pin bearing surfaces have undergone a hardening treatment.
18. The transmission of claim 8 , in which selected TTE housing bearing surfaces include curvature.
19. The transmission of claim 8 , in which selected TTE housing bearing surfaces include angled faces.
20. An articulated transmission disposed to transmit torque via misaligned rotation, the transmission comprising:
a shaft having an axial shaft centerline about which the shaft is disposed to rotate;
a plurality of shaft pins, each shaft pin extending radially from the shaft centerline, each shaft pin further providing a convex shaft pin bearing surface thereon;
a generally cylindrical housing having an axial housing centerline about which the housing is disposed to rotate, the housing having a plurality of housing cavity receptacles formed therein, each housing cavity receptacle for receiving a corresponding shaft pin; and
a plurality of torque transfer elements (TTEs), each TTE providing a concave TTE pin bearing surface and a TTE housing bearing surface;
wherein each housing cavity receptacle provides a housing bearing surface;
wherein a shaft pin and a TTE are received into each housing cavity receptacle such that within each housing cavity receptacle, the convex shaft pin bearing surface is received onto the concave TTE pin bearing surface and the TTE housing bearing surface opposes the housing bearing surface;
wherein, responsive to misaligned rotation of the shaft centerline with respect to the housing centerline and regardless of angular deflection of the shaft centerline with respect to the housing centerline experienced within each housing receptacle during an articulated revolution of the shaft: (1) the concave TTE pin bearing surfaces are free to slidably displace relative to the convex shaft pin bearing surfaces; and (2) the TTE housing bearing surfaces are free to slidably displace against corresponding housing bearing surfaces;
wherein the TTEs float at least generally parallel to an unfitted shaft centerline when the TTE housing bearing surfaces slidably displace against corresponding housing bearing surfaces;
wherein selected ones of the TTE pin bearing surfaces and the TTE housing bearing surfaces include a laminate.