EFFICIENCY - POWER - UNSEEN
THE ULTIMATE PERFORMANCE ENHANCING
CRYO CONCEPT AND DESIGN
DEVELOPED FOR KO MOTORS
Power delivery from a brusless motor largely depends on the operating temperature throughout the duty cycle, this includes both the stator, magnets and windings.
While initial power may be high, a motor can quickly heat soak causing the available power to rapidly reduce well below the potential of Individual components (mainly the magnets and windings).
KO has identified this as the main limiting factor when developing a motor to meet the high demands placed on a multi rotor motor.
Our solution has been to completely redesign the fundemental components and the way they interact.
Firstly the ACPC ring design on all of the KO motor offerings, this allows for maximum air flow through the stator and magnet assembly without robbing the motor of power to drive a fan style system however this is only the first step .
CRYO SPRAY IS THE NEXT STEP IN OUR EVOLUTION OF THE KO MOTOR USING PATENTED TECHNOLOGY
The next step is where Cryo comes into play . Cryo spray is a specially formulated freezing agent designed to drop the standing temp of the stator, windings and magnets to -30°c ( depending on ambient temp ) in order to both increase power, as well as lengthen the operational envelope the motors can deliver peak power before heat soak causes power loss.
This sounds simple in theory, however many hurdles had to be overcome to allow the motors individual parts to cope with the high variances in operating temperature (from -30°to +30 °c or higher).
To achieve this many problems had to be overcome. Testing showed stators will de-laminate after several uses, due to the drastic temperature changes (because each stator lamination will shrink and expand at a different rate causing failure), In addition aluminium parts would shrink at a different rate to metal parts when the Cryo spray was applied, causing failure of the entire structure after very short use.
AFTER ALMOST A YEAR OF R&D AND THE IMPLEMENTATION OF MANY NEW DESIGN FEATURES.
MORE TECHNICAL INFO
We also had failure of the adhesive used to attach the magnets to the bell etc and as if that was not enough, the effect of using a freezing agent on the stator causes a high degree of condensation ( moisture ) to accumulate resulting in rust to form very quickly after an initial application especially in humid conditions.
Lastly and possibly the most challenging problem we faced is press fitted components such as the shaft, the shaft in smaller motors relies on a very tight press fit to ensure concentric mating of the shaft and bell to eliminate any vibrations.
Here is how we overcame these limitations and produced a motor capable of taking full advantage of this new tech .
Firstly the stator de-laminating , we sourced a stator coating normally used in the automobile industry. This coating allows the stator to uniformly shrink and expand under the extreme temperature variance from -30°c to +30°c or higher, this coating has also eliminated the potential for the stator to rust due to the build of of moisture caused by condensation. Next we sourced an adhesive also from the automotive industry for the magnets and bell assembly with a temperature spread of -65°c to +265°C.
This adhesive has also been used when assembling the press fitted components such as the shaft ensuring no slipping or movement when subjected to the extreme changes in temperature.
A WHOLE RAFT OF INDUSTRY FIRST DESIGNS AND PATENTS - DRIVING FPV INTO THE FUTURE
What can you expect to gain ?
Bench and flight tests have shown between 10% and 15% increase in power over a non Cryo sprayed motor. However that is only half the data . The real advantage is how long the motor can produce that peak power number.
Typically a motor with about 1800g of thrust will drop to 1700g within 5 seconds on a bench test and sub 1600g within 20seconds at WOT (if it makes it that far without heat soaking and completely failing due to burnt windings). When Cryo is used this is not the case .
The power figure at 20 seconds is almost identical as in the first 5 seconds and depending on ambient temperature the motor delivers close to peak power for 40- 50 seconds before heat soak begins and the heat soak effect starts to take take place , In a non static "in flight" test the effect last longer again before heat soak becomes a factor.
This all adds up to around 1 minute of higher performance at which time the motor is at ambient temperature and a further minute before the motor is at the same operating temperature realised by a motor subjected to the same duty cycle without Cryo.