Patented CTR Triplex Ceramic 2.0 Turbocharger
Historically, a great deal of effort was expended in the early years of small turbocharger development to design a bearing system that had sufficient durability to make them commercially viable. Extensive research programs undertaken in the 1960's resulted in satisfactory solutions to rotor instability (oil whirl) and blade vibration problems, and allowed the small turbocharger to be accepted for use by major engine builders. However, the full floating sleeve bearing systems with a stationary thrust bearing performed well in the production turbochargers but exhibited an appreciable friction loss at their high speeds of operation. The inner and outer oil films in floating sleeve bearings have significant viscosity that produces appreciable friction losses due to oil film shear when the rotor is accelerated. In addition, the friction loss attributed to the stationary thrust bearing is proportional to the fourth power of the radius. The sum total of these losses can amount to several horsepower at high rotor speeds, resulting in mechanical efficiencies in the middle 90% range for conventional sleeve bearing systems.
The acceleration rate of a turbocharger rotor is a function of the rotor inertia and the friction losses in the bearing system. To reduce the bearing system friction losses, a significant effort has been made over the years by various companies to replace the sleeve bearing systems with ball bearings due to their inherent low friction losses. These attempts have been essentially unsuccessful until the TRIPLEX CERAMIC™ ball bearing system was invented.
The TRIPLEX CERAMIC™ system consists of three angular contact ball bearings with ceramic balls mounted in an elongated stainless steel cylinder that is free to rotate in a smooth bore in the turbocharger bearing housing. Other internal components are also now made of stainless steel. The outside diameter of the steel cylinder is fed with lube oil from the engine, and this outer oil film provides a cushion against shock and vibration. Two angular contact bearings are mounted in tandem in the compressor end of the steel cylinder and carry axial thrust in both directions. A single angular contact bearing is slidably mounted in the turbine end of the steel cylinder with its outer race against a pre-load spring. Thus, the turbine end bearing is free to move axially when the shaft elongates from heat conducted into the shaft from the hot turbine wheel. The steel cylinder containing the three bearings comprises the complete bearing system and can be inserted or removed from the bearing housing bore as an assembly by hand, making the TRIPLEX CERAMIC™ turbocharger easily serviceable and rebuildable.
Racing applications require a turbocharger that accelerates fast to build boost pressure as rapidly as possible, allowing the engine to develop high torque at low engine speed and produce very high power output at maximum engine speed. A turbocharger equipped with the TRIPLEX CERAMIC™ bearing system does exactly that. The ball bearings operate with rolling friction only so they allow rotor acceleration much faster than sleeve bearing systems.
In street applications, the acceleration rate of a vehicle equipped with a TRIPLEX CERAMIC™ ball bearing turbocharger is enhanced and moves the engine out of inefficient operating ranges more rapidly. An improvement in fuel consumption is the usual result when a vehicle is accelerated faster. Under steady-state operation, the lower HP losses in the TRIPLEX CERAMIC™ ball bearing system makes more power available to the turbocharger compressor, resulting in higher intake manifold pressure. In most cases, higher boost can make an additional contribution to improving engine fuel consumption.
The TRIPLEX CERAMIC™ ball bearing system using engine lube oil has been in quantity production for over ten years and has established an outstanding record for durability and performance. A complete line of ball bearing turbochargers is available from Comp Turbo Technology Inc. with various compressor and turbine wheel trims to tailor their performance to match specific engine performance requirements, whether they be racing, street, marine or stationary. The superior acceleration of the Comp Turbo ball bearing turbochargers can produce the ultimate in engine and vehicle response.