Yoshito Ejima

Studies on friction and wear characteristics of cam and follower: influences of soot contamination in engine oil

Abstract In order to clarify the friction and wear mechanism of the contact between cam and follower in the valve train incorporated in an EGR system, an experimental investigation was performed with a cam-follower test rig. A fresh CD-class SAE10W-30 multigrade oil and its deteriorated versions with different contaminants were tested. Changes in friction force and amount of wear were measured during the course of the tests. The influence of the soot in the deteriorated oil was examined by mixing the exhaust gas soot blended with the dispersant, ZnDTP and MoDTC additives. Results are summarized as follows. (1) The friction fluctuated and gradually increased with the lapse of time in case of contaminated oils with the soot. (2) Under the coexistence of ZnDTP and MoDTC, however, the friction gradually decreased in spite of existence of soot. (3) The soot dispersed in the oil increased wear rate and reduced the anti-wear effect of the ZnDTP. (4) The smallest wear rate was observed because the anti-wear effect was maintained owing to the MoDTC.

Improvement of Lubrication for Cam and Follower

In order to improve the lubrication between cam and follower of internal combustion engines, the influences of materials or oil viscosity and additives on the friction and scuffing characteristics have been examined with a test rig by increasing the contact load at a constant revolution speed. Also the effects of oil supply through the oil-hole of the camshaft on the reduction of friction and the prevention of scuffing have been examined. From the experiments the following results were made obvious. Firstly, the effect of the material on the reduction of friction or the prevention of scuffing is dependent upon the combination of cam and follower materials. The follower material of hard sintered metal or silicon nitride ceramics is superior in both effects to chilled cast iron when mating with the cam material of hardened S48C steel cam. Secondly, as the viscosity of base-oil becomes low, the friction increases or decreases depending on oil additives, but the scuffing resistance always becomes small. The o...

Studies on the measuring method of the total friction loss of internal combustion engines

Abstract In the present study a new test method is investigated to measure the total friction loss of engines over the whole range of speed and load. It is based on the idea that the friction loss close to the true one of fired and braked engines can be measured by the run-out method because the temperature mainly influencing the friction loss is almost stable for the short run-out test duration. From the test results and the comparison with those measured by other conventional test methods, the following becomes evident: 1. (1) The total friction mean effective pressure slightly increases as the revolution speed becomes high, but it decreases as either the load or the cooling water temperature becomes high. 2. (2) The total friction mean effective pressure measured by the present method is smaller than that measured by the run-out method, the motoring method or Willans-line method, but it is larger than that measured by the indicated pressure diagram method.