Apparatus for accelerating the onset of wear related damage and distress on a circumferential cam surface

Abstract

Apparatus for accelerating the onset of wear related damage on a circumferential cam surface including a structure for supporting a camshaft including the circumferential cam surface, a plurality of rollers having respective circumferential roller surfaces, and structures supporting the rollers at respective locations adjacent the structure for supporting the camshaft for positioning the circumferential roller surfaces for circumferential rotating contact with the circumferential cam surface. The apparatus includes a mechanism operable for rotating the camshaft with the circumferential cam surface and the circumferential roller surfaces in the circumferential rotating contact. The apparatus further includes a mechanism for variably biasing the respective rollers against the camshaft during the circumferential rotating contact simulative of actual operating conditions. The apparatus has application for evaluating wear related conditions of cams, rollers and other followers used for fuel injector actuation for internal combustion engines, as well as other applications such as for operation of engine intake and exhaust valves and the like.

What is claimed is:  
     
       1. Apparatus for accelerating the onset of wear related damage on a circumferential cam surface, comprising: 
       a structure for supporting a camshaft including the circumferential cam surface for rotation about an axis of the circumferential cam surface;  
       a plurality of rollers including respective circumferential roller surfaces, and structures supporting the rollers at respective locations adjacent the structure for supporting the camshaft for positioning the circumferential roller surfaces for circumferential rotating contact with the circumferential cam surface;  
       a mechanism operable for rotating the camshaft with the circumferential cam surface in circumferential rotating contact with the circumferential roller surfaces; and  
       mechanisms operable for variably biasing the respective rollers against the camshaft during the circumferential rotating contact.  
     
     
       2. Apparatus, as set forth in claim  1 , further comprising a device operable for detecting changes in at least one characteristic of the circumferential rotating contact between the circumferential cam surface and at least one of the circumferential roller surfaces indicative of the onset of the wear related damage. 
     
     
       3. Apparatus, as set forth in claim  2 , further comprising: 
       a device operable for applying a potential across the circumferential rotating contact between the circumferential cam surface and the at least one of the circumferential roller surfaces, wherein the at least one characteristic comprises the potential.  
     
     
       4. Apparatus, as set forth in claim  1 , wherein the mechanisms operable for variably biasing the respective rollers against the camshaft comprise hydraulic lifters. 
     
     
       5. Apparatus, as set forth in claim  4 , wherein the structures supporting the respective rollers each comprise a pivotally mounted rocker arm having one end supporting the roller and an opposite end in contact with the respective hydraulic lifter. 
     
     
       6. Apparatus, as set forth in claim  1 , wherein the mechanisms operable for variable biasing the rollers against the camshaft are operable to bias the respective rollers against the camshaft with forces variable within a range of from about 100 pounds to about 10,000 pounds. 
     
     
       7. Apparatus, as set forth in claim  1 , wherein the plurality of rollers are located at uniform angularly spaced locations around the structure for supporting the camshaft. 
     
     
       8. Apparatus, as set forth in claim  7 , comprising at least three of the rollers. 
     
     
       9. Apparatus, as set forth in claim  7 , comprising two of the rollers. 
     
     
       10. Apparatus, as set forth in claim  1 , wherein the structure for supporting the camshaft supports the camshaft for rotation about an axis therethrough and further comprises a drive motor operable for rotating the camshaft. 
     
     
       11. Apparatus, as set forth in claim  6 , wherein the camshaft comprises as axis, the circumferential cam surface comprises a concentric portion concentric about the axis and a lobe portion eccentric about the axis, and the mechanisms operable for variably biasing the rollers against the camshaft are operable to bias the respective rollers against the camshaft with a force of from about 2000 pounds to about 10,000 pounds when the circumferential roller surfaces are in circumferential rotating contact with the lobe portion of the circumferential cam surface and a substantially lesser force when the circumferential roller surfaces are in circumferential rotating contact with the concentric portion thereof.