Contact gearing

Abstract

A form of gearing with teeth having circular arc profiles and a particular pressure angle which together produce engagement and disengagement in pure rolling. The shearing action tangential to the tooth profiles associated with compressive deformation of the tooth faces is made to exactly offset the shearing action in the opposite direction imposed by the meshing of the teeth.

I claim: 
     
       1. A pair of mating gears comprising a driving gear and a driven gear turned by pressure exerted by the teeth of said driving gear, mechanical means connected to said driven gear to remove power therefrom, said teeth being formed to have active profiles in planes perpendicular to the pitch line for which the pressure angle is greater than 40°, the active portion of said profiles of one of said pair being curved, a portion of one working surface of the teeth of one of said pair intersecting the pitch circle of said one of said pair, .Iadd.the radii of curvature of the undeformed profiles of the teeth of both of said pair being greater than half the circular pitch, .Iaddend.and both flanks of each of said teeth on one of said pair having at all points diametral pressure angles of at least 0°. 
     
     
       2. A pair of mating gears according to claim 1 wherein said teeth extend across the rims of said gears in a direction slantingly disposed with respect to the pitch line of said pair. 
     
     
       3. A pair of mating gears according to claim 1 wherein the radially outermost extremity of the contact area developed between meshed teeth is adjacent to but not truncated by the tip of the teeth of one of said pair when said pair is transmitting the maximum allowable torque. 
     
     
       4. A pair of mating gears according to claim 1 wherein said profiles extend on both sides of the pitch surfaces of said pair. 
     
     
       5. A pair of mating gears according to claim 1 wherein the centers of curvature of said active profiles of the teeth of one of said pair are substantially removed from the pitch surface of said one of said pair. 
     
     
       6. A pair of mating gears according to claim 1 wherein said profiles are circular arcs. 
     
     
       7. A pair of mating gears according to claim 1 wherein the active profiles of said teeth in the normal plane are circular arcs. 
     
     
       8. A pair of mating gears according to claim 1 wherein the square of the cotangent of the pressure angle in planes normal to said pitch line is substantially equal to one minus the quotient of the relative radius of curvature of said profiles times the sum of the reciprocals of the pitch radii of said pair divided by the sine of said pressure angle. 
     
     
       9. A pair of mating gears according to claim 1 wherein a semifluid lubricant is stored in at least one recess in one of said pair. 
     
     
       10. A pair of mating gears according to claim 1 wherein the tooth surfaces of one of said pair are treated with a solid lubricant. 
     
     
       11. A pair of mating gears according to claim 1 wherein the engaging surfaces of said teeth of one of said pair are formed of a soft resilient material supported by a metallic substructure. 
     
     
       12. A pair of mating gears according to claim 1 wherein said teeth of one of said pair are formed of a moldable material. 
     
     
       13. A pair of mating gears according to claim 1 wherein one of said pair has teeth of soft resilient material and the other has teeth of metal adapted to facilitate heat dissipation from said one of said pair. 
     
     
       14. A pair of mating gears according to claim 1, wherein both said gears are external. 
     
     
       15. A pair of mating gears according to claim 1, wherein the number of teeth on said gears differs by more than two. 
     
     
       16. In a pair of mating gears: teeth formed to have nonconjugate profiles in sections perpendicular to the pitch line of said pair,   said profiles having a relative radius of curvature at said pitch line smaller than the sine of the pressure angle in said sections divided by the sum of the reciprocals of the pitch radii of said pair, whereby separation of said profiles is effected at all profile positions removed from said pitch line when said pair is in mesh but not transmitting torque,   said pressure angle being greater than 40°, whereby the shearing action tangential to said tooth profiles associated with compressive deformation of the tooth faces when said pair is transmitting torque offsets most of the shearing action in the opposite direction imposed by the meshing of said teeth.   
     
     
       17. A pair of mating gears according to claim 16 wherein said teeth extend across the rims of said gears in a direction slantingly disposed with respect to the pitch line of said pair. 
     
     
       18. A pair of mating gears according to claim 16 wherein the radially outermost extremity of the contact area developed between meshed teeth is adjacent to but not truncated by the tip of the teeth of one of said pair when said pair is transmitting the maximum allowable torque. 
     
     
       19. A pair of mating gears according to claim 16 wherein said profiles extend on both sides of the pitch surfaces of said pair. 
     
     
       20. A pair of mating gears according to claim 16 wherein the centers of curvature of said active profiles of the teeth of one of said pair are substantially removed from the pitch surface of said one of said pair. 
     
     
       21. A pair of mating gears according to claim 16 wherein said profiles are circular arcs. 
     
     
       22. A pair of mating gears according to claim 16 wherein the active profiles of said teeth in the normal plane are circular arcs. 
     
     
       23. A pair of mating gears according to claim 16 wherein the square of the cotangent of the pressure angle in planes normal to said pitch line is substantially equal to one minus the quotient of the relative radius of curvature of said profiles times the sum of the reciprocals of the pitch radii of said pair divided by the sine of said pressure angle. 
     
     
       24. A pair of mating gears according to claim 16 wherein a semifluid lubricant is stored in at least one recess in one of said pair. 
     
     
       25. A pair of mating gears according to claim 16 wherein the tooth surfaces of one of said pair are treated with a solid lubricant. 
     
     
       26. A pair of mating gears according to claim 16 wherein the engaging surfaces of said teeth of one of said pair are formed of a soft resilient material supported by a metallic substructure. 
     
     
       27. A pair of mating gears according to claim 16 wherein said teeth of one of said pair are formed of a moldable material. 
     
     
       28. A pair of mating gears according to claim 16 wherein one of said pair has teeth of soft resilient material and the other has teeth of metal adapted to facilitate heat dissipation from said one of said pair. 
     
     
       29. In a pair of mating gears: teeth formed to have nonconjugate profiles in sections perpendicular to the pitch line of said pair,   said profiles having a relative radius of curvature at said pitch line smaller than the sine of the pressure angle in said sections divided by the sum of the reciprocals of the pitch radii of said pair, whereby separation of said profiles is effected at all profile positions removed from said pitch line when said pair is in mesh but not transmitting torque,   said pressure angle being greater than 45°, whereby the shearing action tangential to said tooth profiles associated with compressive deformation of the tooth faces when said pair is transmitting torque offsets all of the shearing action in the opposite direction imposed by the meshing of said teeth.   
     
     
       30. A pair of mating gears according to claim 29 wherein said teeth extend across the rims of said gears in a direction slantingly disposed with respect to the pitch line of said pair. 
     
     
       31. A pair of mating gears according to claim 29 wherein the radially outermost extremity of the contact area developed between meshed teeth is adjacent to but not truncated by the tip of the teeth of one of said pair when said pair is transmitting the maximum allowable torque. 
     
     
       32. A pair of mating gears according to claim 29 wherein said profiles extend on both sides of the pitch surfaces of said pair. 
     
     
       33. A pair of mating gears according to claim 29 wherein the centers of curvature of said active profiles of the teeth of one of said pair are substantially removed from the pitch surface of said one of said pair. 
     
     
       34. A pair of mating gears according to claim 29 wherein said profiles are circular arcs. 
     
     
       35. A pair of mating gears according to claim 29 wherein the active profiles of said teeth in the normal plane are circular arcs. 
     
     
       36. A pair of mating gears according to claim 29 wherein the square of the cotangent of the pressure angle in planes normal to said pitch line is substantially equal to one minus the quotient of the relative radius of curvature of said profiles times the sum of the reciprocals of the pitch radii of said pair divided by the sine of said pressure angle. 
     
     
       37. A pair of mating gears according to claim 29 wherein a semifluid lubricant is stored in at least one recess in one of said pair. 
     
     
       38. A pair of mating gears according to claim 29 wherein the tooth surfaces of one of said pair are treated with a solid lubricant. 
     
     
       39. A pair of mating gears according to claim 29 wherein the engaging surfaces of said teeth of one of said pair are formed of a soft resilient material supported by a metallic substructure. 
     
     
       40. A pair of mating gears according to claim 29 wherein said teeth of one of said pair are formed of a moldable material. 
     
     
       41. A pair of mating gears according to claim 29 wherein one of said pair has teeth of soft resilient material and the other has teeth of metal adapted to facilitate heat dissipation from said one of said pair. 
     
     
       42. In a pair of mating gears: teeth formed to extend across the rims of said gears in a direction slantingly disposed with respect to the pitch line of said pair,   said teeth being formed to have nonconjugate active profiles in sections perpendicular to said pitch line as a result of having a relative radius of curvature at said pitch line smaller than the sine of the pressure angle in said sections divided by the sum of the reciprocals of the pitch radii of said pair, whereby separation of said profiles is effected at all points removed from said pitch line when said pair is in mesh but not transmitting torque,   said gears and said teeth having a relation between pitch radii, helix angle, pressure angle, radii of curvature of engaging surfaces, normal diametral pitch, allowable tooth surface stress, and effective moduli of elasticity, such that when said pair is transmitting the maximum allowable torque the segment of the elliptical boundary of the contact area between said teeth furthest removed from said pitch line is substantially tangent to the addendum surface of the larger of said pair, said pressure angle being greater than 40°.   
     
     
       43. A pair of mating gears according to claim 42 wherein said pressure angle is larger than 40°, whereby the shearing action tangential to said tooth profiles associated with compressive deformation of the tooth faces when said pair is transmitting torque offsets most of the shearing action in the opposite direction imposed by the meshing of said teeth. 
     
     
       44. A pair of mating gears according to claim 42 wherein said pressure angle is larger than 45°, whereby the shearing action tangential to said tooth profiles associated with compressive deformation of the tooth faces when said pair is transmitting torque offsets all of the shearing action in the opposite direction imposed by the meshing of said teeth. 
     
     
       45. A pair of mating gears according to claim 42 wherein the face width times the tangent of the helix angle divided by the circular pitch is substantially equal to an integer. 
     
     
       46. A pair of mating gears according to claim 42 wherein said profiles extend on both sides of the pitch surfaces of said pair. 
     
     
       47. A pair of mating gears according to claim 42 wherein the centers of curvature of said active profiles of the teeth of one of said pair are substantially removed from the pitch surface of said one of said pair. 
     
     
       48. A pair of mating gears according to claim 42 wherein said profiles are circular arcs. 
     
     
       49. A pair of mating gears according to claim 42 wherein the active profiles of said teeth in the normal plane are circular arcs. 
     
     
       50. A pair of mating gears according to claim 42 wherein the square of the cotangent of the pressure angle in planes normal to said pitch line is substantially equal to one minus the quotient of the relative radius of curvature of said profiles times the sum of the reciprocals of the pitch radii of said pair divided by the sine of said pressure angle. 
     
     
       51. A pair of mating gears according to claim 42 wherein a semifluid lubricant is stored in at least one recess in one of said pair. 
     
     
       52. A pair of mating gears according to claim 42 wherein the tooth surfaces of one of said pair are treated with a solid lubricant. 
     
     
       53. A pair of mating gears according to claim 42 wherein the engaging surfaces of said teeth of one of said pair are formed of a soft resilient material supported by a metallic substructure. 
     
     
       54. A pair of mating gears according to claim 42 wherein said teeth of one of said pair are formed of a moldable material. 
     
     
       55. A pair of mating gears according to claim 42 wherein one of said pair has teeth of soft resilient material and the other has teeth of metal adapted to facilitate heat dissipation from one of said pair.