Core Technology
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The technology which possesses the real heart!
Even after 100 years, the standard of energy machine will be the KTurbo


The second industrial revolution is being realized by KTurbo with the 5 core technologies such as the air foil bearing, the impeller with precision casting, the capability of aerodynamic technology high velocity motor with high efficiency and inverter


Air Foil Bearing

The air bearing of Kturbo which is operated without mechanical friction and lubricant is the first semi-permanent and none-oil feeding lubricating system of the world. The rotation shaft is floated by the pressure which is converted from the air flow, generated during the rotaion of shaft, between the bearing and shaft, and it also performs the fuction of lubrication as well. In the case of this core technology, electric power is transmitted th the shaft without mechanical friction, therefore, high system efficiency without noise is provided as well as semi-permanent lif of durability







The impeller of Kturbo with the most advanced aerodynamic system is identical with the leading technology of aeronautical engineering. Compared to existing aluminum impeller, it has semi-permanent life, and provides, higher pressure with great strength, and has high efficiency. High efficiency imperllers are directly produced with the process and casting equipment in which high level of technologies are combined



PM Motor

From 5,000 to 200,000 rpm, and from 5 to 600 hp, Ktrubo is proud of the high velocity motor with 97% of high efficiency. Separate starting board is not required as it can be started with the current of 5% level of the rated current. In addition, accurate control can be accomplished under the environment of the motor with high temperature by applying the sensor-less drive technology



Technical Level


- support up to 90 kg of weight
- Rotating speed reaches over 50,000 RPM
- applied on 3,000 products for 10 years

What is the foil bearing ?

- Foil bearing uses air rather than oil for lubrication. Its advantages are flexibility and cost effectiveness
- Foil bearings in the field of aeronautical engineering have been used for ACM (Air Cooling Machine) which is the core component to control pressure and temperature inside of aircraft cabins since 1970's. The foil bearing without any oil system does not contaminate inside of the cabin and makes for a stable long term operation without maintenance. Furthermore, even if it is broken, the other turbo elements are not damaged. Foil bearings used for Boeing 747 operate for more than 100,000 hours without maintenance



Comparison of bearings


case Foil Bearing Magnetic Bearing Tilting Pad Bearing Ball Bearing
Lubricant No No YES YES
Durability Semi-permanent Semi-permanent Semi-permanent need to exchange
Maintenance No exchange aux. ball bearing regular inspection by 5 years exchange by regular running interval
Reliability 20 5 1 1
Ball Bearing No damage upon aux. ball bearing breakable by reduced oil pressure breakable by reduced oil pressure
Probability for erros No(fully mechanical) error for controller breakable when unsuitable maintenance of oil system breakable when unsuitable maintenance of oil system
System complexity simple(fully mechanical) - complex controller
- electric leakage to bearing
- limiting lifetime of coil
complex oil system(Pump, Filter,pressure sensing system, ..) complex oil system(Pump, Filter,pressure sensing system, ..)
Loss of power below 0.5% of motor power when high speed above 1% of motor power when high speed 10% of total power containing gear loss 5% of total power containing gear loss
Cost for AS 1 100 30 30




Design through 3 dimensional flow analysis




Modified lost wax method can produce any complicated shaped goods at lower cost than conventional machining cutting method



Impeller Balancing & Over speed Test

Accurate dimension and good roughness by lost-wax method

Impeller with wall thickness of 0.3 mm can be cast




Material Aluminum Impeller SUS630 Impeller
Life time 10 years Over 30 years
Impact resistance weak strong
Margin for yield stress small (normally below 20%) large (above 50%)
Price 1x 3x
Aerodynamic performance small sweep angle for low stress design makes low efficiency and reduced operating range. optimum sweep angle makes high efficiency and wide operating range
Long term performance Considerable decrease of performance due to airstream wear No noticeable performance change



Technical Level : manufacturing 400HP class motor/inverter


PM(permanent magnet) PM motor uses a permanent magnet rotor, and moves by the electromagnetic rotating force from the stator. It is similar to the small DC motor whose brushes and commutator are replaced with transistors or similar electric switch


Features of KTurbo motor and inverter



VFD (Variable Frequency Drive)
The world largest capacity (300kW class)
Small starting current (below 10% of rated value)
High efficiency (95~97%)
High speed (up to 65,000 rpm)
Maintains high efficiency at partial loading condition
Sensor less drive (high temperature reliability)



Comparison of motors


case induction motor+gear high speed induction motor+Inverter PM motor+Inverter
(shaft PWR / electric PWR)
0.95(motor) * 0.95(gear) = 0.9 0.93(motor) * 0.97(inverter) = 0.9 0.95(motor) * 0.97(inverter) = 0.92
analysis for efficiency efficiency of high efficient motor becomes up to 90%, but the loss induced by gear is inevitable. Energy is dissipated during generaing induction current to rotor, especially at high speed this pheno-mena becomes the more serious. It decreases efficiency. No energy is required for the rotor with permanent magnet and the efficiency becomes optimized beca-use of no slip.
size large because of the size of gear box, mechanical bearing and com-plex lubrication system large because induction current density is lower than that of permanent magnet small compared with induction type
Life time durability of bearing and gear durability of bearing durability of bearing
Control of rotating speed unable able able