Koenigsegg Direct Drive
Paving the way
The Koenigsegg Direct Drive Transmission (KDD) was invented by Christian von Koenigsegg and developed for the Regera by the Koenigsegg Advanced Engineering team. The patent-pending KDD replaces the combustion engine’s traditional transmission – the gearbox as you know it is removed from the car. As the gearbox is responsible for both added weight and efficiency losses, any chance to remove this double-negative is welcome.
In its place, the KDD provides direct drive to the rear axle from the combustion engine. This is done without the need for a multitude of gears or a variable transmission, all of which have inherently high energy losses.
Koenigsegg Direct Drive
FOUR KEY
ELEMENTS
TOGETHER
‘HydraCoup’ is a bespoke hydraulic coupling developed in-house at Koenigsegg, specifically for the Regera. HydraCoup is basically a very advanced torque converter with a lock-up functionality; the all-important linchpin that allows smooth and progressive power transfer from the combustion engine to the single-speed driveline.
Koenigsegg’s three axial flux electric motors are optimized in-house and are extremely power dense, making them a key ingredient for the KDD. Aside from providing extreme responsiveness from zero rpm, these electric motors also allow for torque vectoring, regenerative braking and energy conversion.
KDD features our Formula 1 grade, super-dense and super-compact battery pack.
The battery pack is key to the Regera’s ability to deliver rapid acceleration. It weighs just 64 kg, which is incredibly light, given that it can discharge up to 500 kW of power.
In the Regera, its motorsport-grade cell technology can discharge power approximately 10 times faster than a typical pure electric car, and can accept re-gen around 10 times quicker as well.
A twin-turbo V8 producing 1,100hp and 1,000Nm was used in the Koenigsegg Regera.
Massive torque from stand-still
The Regera has a final drive ratio of 2.73:1, the equivalent to seventh gear in the Koenigsegg Agera. Ever tried to take off in 7th gear? There is simply not enough torque available in a regular car to start at such a high gear. To combat this, the Regera's Koenigsegg Direct Drive has two types of propulsion working together to move the car: electric propulsion and the internal combustion engine (ICE).
The Regera’s ICE has 1,100hp and 1,250Nm of torque, but peak torque is not available at 0 rpm. Starting from stand-still is therefore compromised when using the ICE alone. Enter the Regera’s electric drive, providing 670hp of drive and more importantly 3500 Nm of torque direct to the rear wheels (the equivalent of 1000 nm on the crank), which is available from standstill up to 3500 crank rpm. Electric torque eventually tapers off but it will still assist all the way up to 8000 crank rpm.
The instant torque from the electric motors from 0 rpm and upwards acts like the lower gears of traditional transmissions, pulling the car smoothly and powerfully from standstill.
A Regera case study
ICE and HydraCoup at play
While the ICE is not the primary driving force for the wheels from standstill, the HydraCoup will gradually feed power from the ICE into the drivetrain until the HydraCoup locks up. This means the ICE is driving the wheels mechanically without a traditional transmission while at the lowest possible losses of any transmission in this mode.
If one is cruising on ICE power alone at 150 km/h and floors the accelerator, the KDD system will engage electric drive to help push from 150 to 250 km/h in just 3.2 sec. As you coast back down to 150, the ICE system and recharge via de-acceleration begins to fill the battery so that you’re ready to do it all again – and again, and again.
It’s this massive power and torque delivery in combination with the ICE that enables the Regera to minimise mechanical losses by removing the traditional transmission. The KDD system allows the Regera to be super responsive and smooth at the same time. It will provide the fastest 0-400 km/h acceleration time in the world thanks to its unique power delivery, vastly reduced mechanical losses, and much lower component weight.
Cruising with confidence in the Regera
KDD Explained
Watch Engineering Explained's Jason Fensk dive into the Koenigsegg Direct Drive.