Enhancing the parameters of starved EHL point conjunctions by artificially induced replenishment

The authors present in this paper a mechanism for enhancing the replenishment in EHL point contacts under extreme starvation. The mechanism of replenishment depends on channeling the available lubricant towards the centerline of the overrolled track by using a flexible slider (scraper) with a micro-slot concentric with the track. The slider accumulates the scraped lubricant to be hydrodynamically entrained through the micro-slot resulting in enriching the depleted track with fresh lubricant. The efficiency of induced replenishment is assessed by measuring the coefficient of friction (COF) and the film thickness over time in a ball-on-disc device. The results show a significant reduction of friction about 31% for oil lubrication and about 25% for grease lubrication after introducing the mechanism of artificially induced replenishment. On the other hand, the central film thickness has been doubled many times for oil and grease lubrication. The optical interferometric images show that the air-oil meniscus disappeared upstream far away from the Hertzian contact which means that the contact transformed from the severely starved to the fully flooded regime with a limited amount of lubricant. The reliability of this method is high since the observed benefits are stable over time.