1. Basic principle

The key achievements by the power system of clean energy vehicle are fulfilled by integrating electrical drive train (motor, inverter and battery) as power assistance into vehicle power train and realize fuel savings as follows:
(1) Keep ICE operation in the most efficienct section of power curves, less power and displacement required for engine.
(2) Keep vehicle working in all electrical operation mode when vehicle is in low speed or idling.
(3) To improve the fuel economic by utilizing the regenerative braking energy via energy absorbed and stored in flywheel or battery and then released during acceleration.

The full hybrid system “Hybrid Synergy Drive^®” (HSD) by Toyota Prius has successfully achieved fuel savings mentioned above. But the output power by NI-MH battery installed in Prius is restricted due to the character of low cost NI-MH battery. No more than 30KW of braking energy is recovered by NI-MH battery via driving motor and controller. The rest of braking energy is wasted as thermal energy by mechanical braking and the 100KW total capacity of dual motor in power train cannot be fully utilized. Moreover, its performance on power assistant is also limited by relatively poor output power of its battery pack.

Table: Comparison in the recovering of kinetic energy in different classic driving conditions

Just as  showed in table above, the percentage of braking energy in total driving energy is big under all driving conditions, so it is important to recover more braking energy for fuel saving. Because braking energy is nearly fully absorbed by flywheel in flywheel KERS due to its big power and high efficiency, mechanical braking is nearly avoided and vehicle kinetic energy is fully utilized. Then Prius’ disadvantage of inefficiency in utilizing braking energy is significant eliminated.

By the methods of simulation based on speed data tested in some classic driving conditions and the figures of 0-100km acceleration, it is clear that the power performance and fuel economic by the vehicle installed with HAIKE’s flywheel KERS is significantly superior to Prius. In order to make an equivalent comparison, the power of sub-units such as engine, dual motor, dual-inverter which respectively construct power train in Prius and flywheel KERS is set in same v alue. Moreover, the frequency of discharging in big power by NI-MH battery applied in flywheel KERS is much less than in Prius and it means much longer lifespan of battery in flywheel KERS.

Table: Comparison upon acceleration performance and fuel consumption among HAIKE’s flywheel KERS and several models of hybrid vehicle by Toyota

2. Advantages by HAIKE’s “electrical type” flywheel KERS

(1) In contrast with “energy storage type” flywheel KERS, HAIKE’s “electrical type” flywheel KERS deliver kinetic energy directly in a mechanical way via planetary gear set and it doesn’t need the transformations between kinetic energy-electrical energy-chemical energy, indicating high efficiency of braking energy recovery. The adjustable speed motor performs as management assistance for power & energy and it significantly decreases the dependence upon the capacity of electrical power train.

(2) In contrast with “mechanical type” flywheel KERS, HAIKE’s “electrical type” flywheel KERS utilizes electrical-mechanical control system and the innovative planetary gear set driven by motor as a functional speed ratio converter to replace CVT adopted in the “mechanical type”. In this way, flywheel rotating speed is sustained by energy supplemented via adjustable speed motor and flywheel operating doesn’t need vacuum condition.
 
The character of controlling upon CVT is nonlinear and it has negative influence on ride comfort and consistency. The character of controlling upon motor is vector control and thus can achieve a perfect dynamic control and good ride comfort & consistency. Moreover, the capacity of torque transit by CVT is limited due to its torque transit path which is friction, but the path by gear coupling fulfilled via planetary gear set can afford much bigger flow of torque transit.

(3) Another advantage by HAIKE flywheel KERS is its high safety. Its speed limitation of flywheel spinning is set on 25,000rpm, which is much slower than the other types of flywheel KERS. The radius of its flywheel is designed relatively conservative, allowing a much lower max peripheral speed and double disintegrating stress. Moreover, the safety design in flywheel containment and the architecture capable of dis-gyroscope make it owns much higher safety than the other types of flywheel KERS.

(4) It is capable of being installed into multiple types of vehicle power train such asEV, various types of hybrid vehicles, cars or heavy duty commercial vehicle, etc. Moreover, it is also easy to be installed into retrofitted vehicle’s power train as a sub system.

3. Core technology

HAIKE’s core technologies concentrate in three aspects , including mechanical integration, electrical integration and system control. They are significant innovation in power train technology of clean energy vehicle. HAIKE has been granted or is applying for a portfolio of patents to form its own comprehensive IP system.

Table: Examples of patents on flywheel KERS authored by HAIKE’s core members