Bearing interface with recesses to reduce friction

Abstract

A bearing interface of an apparatus, the apparatus having a first element and a second element configured to move relative to each other during operation of the apparatus, the first element comprising a first bearing surface configured to engage at least a portion of a second bearing surface of the second element thereby defining a contact zone between the first bearing surface and the second bearing surface, the first bearing surface having at least one recess indented into the first bearing surface, wherein the dimension of the recess in the direction of movement of the second element relative to the first element is less than the dimension of the contact zone in the direction of movement of the second element.

The invention claimed is: 
     
       1. A bearing interface of an apparatus, the apparatus having a first element and a second element configured to move relative to each other during operation of the apparatus, the first element comprising a first bearing surface configured to engage at least a portion of a second bearing surface of the second element, thereby defining a contact zone between the first bearing surface and the second bearing surface, the first bearing surface having at least a first recess and a second recess indented into the first bearing surface, a dimension of the first recess and the second recess in a direction of movement of the second element relative to the first element being less than a dimension of the contact zone in the direction of movement of the second element, and wherein the first recess comprises a first shape and the second recess comprises a second shape different than the first shape. 
     
     
       2. The bearing interface according to  claim 1 , wherein the first bearing surface and at least the portion of the second bearing surface are parallel in the contact zone during operation of the apparatus, wherein the second bearing surface is configured to deform elastically upon engagement with the first bearing surface, the dimension of the contact zone in the direction of movement of the second element being defined by a dimension of the elastically deformed portion of the second bearing surface in the direction of movement of the second element. 
     
     
       3. The bearing interface according to  claim 2 , wherein the dimension of the first recess and the second recess in the direction of movement of the second element is less than the dimension of the elastically deformed portion of the second bearing surface in the direction of movement of the second element. 
     
     
       4. The bearing interface according to  claim 1 , wherein a film of lubricant is provided in the contact zone between the first bearing surface and the second bearing surface during operation of the apparatus, the film of lubricant having a film thickness that is substantially constant in the direction of movement of the second element during operation of the apparatus. 
     
     
       5. The bearing interface according to  claim 4 , wherein the dimension of the first recess and the second recess in the direction of movement of the second element is less than a dimension of the film of lubricant in the direction of movement of the second element, wherein the first and second recesses are configured to trap lubricant and increase locally the thickness of the film of lubricant in the contact zone. 
     
     
       6. A machine comprising a bearing interface, the machine comprising an apparatus having a piston cylinder and a piston ring configured to move relative to each other during operation of the apparatus, the piston cylinder comprising an inner surface configured to engage at least a portion of a circumferential surface of the piston ring, thereby defining a contact zone between the inner surface of the piston cylinder and the circumferential surface of the piston ring, the inner surface of the piston cylinder comprising a top region having a first plurality of recesses indented into the inner surface of the piston cylinder, wherein the top region extends towards a bottom end of the inner surface of the piston cylinder away from a contact zone between a top piston ring and the inner surface of the piston cylinder when the piston is at top dead center of a stroke, wherein a dimension of each of the plurality of recesses in a direction of movement of the piston ring relative to the piston cylinder is less than a dimension of the contact zone in the direction of movement of the piston ring. 
     
     
       7. The machine according to  claim 6 , wherein the inner surface further comprises:
 a bottom region having a second plurality of recesses indented into the inner surface of the piston cylinder, wherein the bottom region extends towards a top end of the piston cylinder away from a contact zone between a bottom piston ring and the inner surface of the piston cylinder when the piston is at bottom dead center of the stroke of the piston. 
 
     
     
       8. The machine according to  claim 7 , wherein the top region and the bottom region are separated by a middle region having no recesses indented into the inner surface of the piston cylinder, wherein the top region and the bottom region are spaced apart in a direction of travel of the piston. 
     
     
       9. The machine according to  claim 7 , wherein the top region is offset from the contact zone between the top piston ring and the inner surface of the piston cylinder when the piston is at top dead center of a stroke, and wherein the bottom region is offset from the contact zone between the bottom piston ring and the inner surface of the piston cylinder when the piston is at bottom dead center of the stroke. 
     
     
       10. The machine according to  claim 7 , wherein the contact zone between the top piston ring and the inner surface of the piston cylinder comprises a region bounded by a circumferential contact between a top edge of the top piston ring and the inner surface of the piston cylinder, and a bottom edge of the top piston ring and the inner surface of the piston cylinder when the piston is at top dead center of the stroke. 
     
     
       11. The machine according to  claim 7 , wherein the contact zone between the bottom piston ring and the inner surface of the piston cylinder comprises a region bounded by a circumferential contact between a top edge of the bottom piston ring and the inner surface of the piston cylinder, and a bottom edge of the bottom piston ring and the inner surface of the piston cylinder when the piston is at top dead center of the stroke. 
     
     
       12. The machine according to  claim 10 , wherein the top region extends from the top edge of the top piston ring when the piston is at top dead center of the stroke. 
     
     
       13. The machine according to  claim 10 , wherein the top region extends from the bottom edge of the top piston ring when the piston is at top dead center of the stroke. 
     
     
       14. The machine according to  claim 10 , wherein the top region extends from in between the top and bottom edges of the top piston ring when the piston is at top dead center of the stroke. 
     
     
       15. The machine according to  claim 11 , wherein the bottom region extends from the top edge of the bottom piston ring when the piston is at bottom dead center of the stroke. 
     
     
       16. The machine according to  claim 11 , wherein the bottom region extends from the bottom edge of the bottom piston ring when the piston is at bottom dead center of the stroke. 
     
     
       17. The machine according to  claim 11 , wherein the bottom region extends from in between the bottom and top edges of the bottom piston ring when the piston is at bottom dead center of the stroke. 
     
     
       18. The machine according to  claim 7 , wherein the top region and the bottom region extend towards each other, wherein the machine is an engine or a compressor, and wherein the first and second pluralities of recesses are provided in a bore of a cylinder block or in a bore of a cylinder liner. 
     
     
       19. An apparatus, comprising:
 a bearing interface with a first bearing surface engaging a second bearing surface, thereby defining a contact zone therebetween, the first bearing surface having at least one recess comprising a square-bottomed pocket indented into the first bearing surface, a dimension of the recess in a direction of movement of the second bearing surface relative to the first bearing surface being less than a dimension of the contact zone in the direction of movement of the second bearing surface.