Connecting Rod for an Internal Combustion Engine and Method for Its Production

Abstract

The present invention relates to a connecting rod ( 10 ) for an internal combustion engine, having a small connecting rod eye ( 20 ) for holding a piston pin and having a large connecting rod eye ( 30 ) for holding a crank pin, wherein at least one connecting rod eye ( 20; 30 ) has at least one geometric deviation from a cylindrical inner contour. It is provided according to the invention that the at least one connecting rod eye ( 20; 30 ) is formed by a bore ( 22; 32 ) with a cylindrical inner contour, that the bore ( 22; 32 ) is provided with a coating ( 23; 33 ) comprising a resin with solid lubricant particles embedded therein, and that the coating ( 23; 33 ) forms the at least one geometric deviation from the cylindrical inner contour of the at least one connecting rod eye ( 20; 30 ). The present invention also relates to a method for producing a connecting rod of the type.

1 : Connecting rod ( 10 ) for an internal combustion engine, having a small connecting rod eye ( 20 ) for accommodating a piston pin, and a large connecting rod eye ( 30 ) for accommodating a crank journal, whereby at least one connecting rod eye ( 20 ;  30 ) has at least one geometric deviation from a cylindrical inside contour, wherein the at least one connecting rod eye ( 20 ;  30 ) is formed from a bore ( 22 ;  32 ) having a cylindrical inside contour, that the bore ( 22 ;  32 ) is provided with a coating ( 23 ;  33 ) comprising a resin with solid lubricant particles embedded in it, and that the coating ( 23 ;  33 ) forms the at least one geometric deviation from the cylindrical inside contour of the at least one connecting rod eye ( 20 ;  30 ). 
   
   
       2 : Connecting rod according to  claim 1 , wherein the at least one geometric deviation is configured as at least one stress relief pocket and/or ovality and/or as a shaped bore. 
   
   
       3 : Connecting rod according to  claim 1 , wherein at least one oil collection chamber ( 24 ;  34 ;  25 ;  35 ) is provided in the coating ( 23 ;  33 ). 
   
   
       4 : Connecting rod according to  claim 3 , wherein the at least one oil collection chamber is configured as a channel ( 24 ;  34 ) that runs in the direction of the longitudinal axis (L). 
   
   
       5 : Connecting rod according to  claim 3 , wherein the at least one oil collection chamber is configured as a channel that runs radially relative to the direction of the longitudinal axis (L), surrounding it entirely or in part. 
   
   
       6 : Connecting rod according to  claim 3 , wherein the at least one oil collection chamber is configured as a pocket-shaped recess ( 25 ;  35 ). 
   
   
       7 : Connecting rod according to  claim 1 , wherein the minimum thickness of the coating ( 23 ;  33 ) amounts to 5 μm to 20 μm. 
   
   
       8 : Connecting rod according to  claim 1 , wherein the resin is a thermally cured resin, particularly a polyamide imide resin. 
   
   
       9 : Connecting rod according to  claim 1 , wherein the coating ( 23 ;  33 ) contains 50 wt.-% to 60 wt.-% solid lubricant particles. 
   
   
       10 : Connecting rod according to  claim 1 , wherein the solid lubricant particles consist of a material that is selected from the materials group that comprises graphite, molybdenum sulfide, tungsten disulfide, hexagonal boron nitride, and PTFE (polytetrafluoroethylene). 
   
   
       11 : Connecting rod according to  claim 1 , wherein the solid lubricant particles have a particle size of 1 μm to 3 μm. 
   
   
       12 : Method for the production of a connecting rod ( 10 ) for an internal combustion engine, having a small connecting rod eye ( 20 ) for accommodating a piston pin, and a large connecting rod eye ( 30 ) for accommodating a crank journal, whereby at least one connecting rod eye ( 20 ;  30 ) has at least one geometric deviation from a cylindrical inside contour, wherein first, a bore ( 22 ;  32 ) having a cylindrical inside contour is produced, and subsequently, a coating agent comprising a resin with solid lubricant particles embedded in it is applied to the inside surface of this bore, by means of a coating tool ( 40 ), so that the resulting coating ( 23 ;  33 ) forms the at least one geometric deviation from the cylindrical inside contour of the at least one connecting rod eye ( 20 ;  30 ). 
   
   
       13 : Method according to  claim 12 , wherein the at least one geometric deviation is configured by means of varying the amount of the coating agent given off by the coating tool ( 40 ) and/or by means of varying the advance of the coating tool ( 40 ). 
   
   
       14 : Method according to  claim 12 , wherein the coating agent is applied to the inside surface of the bore ( 22 ;  32 ) with a surface roughness of Ra (average roughness value) £0.8 μm. 
   
   
       15 : Method according to  claim 12 , wherein the coating agent is applied by means of rotation atomization from a rotating nozzle ( 44 ) introduced into the bore ( 22 ;  32 ). 
   
   
       16 : Method according to  claim 15 , wherein the rotation atomization is carried out at a rotation speed of the nozzle ( 44 ) of 14,000 to 18,000 rotations per minute. 
   
   
       17 : Method according to  claim 12 , wherein the inside surface of the bore ( 22 ;  32 ) is pre-heated before and/or during application of the coating agent, preferably up to a temperature of 50° C. to 80° C. 
   
   
       18 : Method according to  claim 12 , wherein a thermally curing coating agent is used, which is subjected to heat treatment immediately after completing the application, preferably at a temperature of 200° C.