Wheel hub motor

Lohner-Porsche, racing version with hub motor all-wheel drive

Megola engine

Wheel hub electric motors for bicycles

A trolleybus with wheel hub motors in Lyon

Hub motor of a Honda FCX

Application in the VW transporter concept eT!

A wheel hub motor is a motor that is built directly into a wheel of a vehicle and at the same time supports the wheel hub . Part of the motor transfers the generated torque to the wheel with which it rotates.

Most designs are electric wheel hub motors, but there were also internal combustion engines. In the case of electric wheel hub motors, both internal and external rotors are conceivable. The hub dynamo is basically similar to the wheel hub motor , an electric machine operated exclusively as a generator in an external rotor design with too little power for drive applications.

history

Wheel hub motors were used in electric vehicles as early as the 19th century. Even Ferdinand Porsche was preparing for the 1900 World Exposition to be Lohner-Porsche -called electric car made with steerable wheel hub motors. In the 20th century there were first attempts with hybrid drives , whereby an internal combustion engine drove a generator , which in turn drove the individual wheels via electric motors. This also works for trailers.

In the 1920s there was also a motorcycle with a five-cylinder rotary engine as a wheel hub drive, the Megola , and a further development, the Killinger & Freund motorcycle .

Today, electric wheel hub motors are mainly used in trams because they make it easier to achieve the lowest possible vehicle floor. The vehicle type Variobahn should be mentioned first in this context . Wheel hub motors with low power are often used in electric wheelchairs , electric scooters and pedelecs . But prototypical cars have also been presented that are powered by wheel hub motors. Furthermore, the use of electric wheel hub motors in aircraft front wheels is currently being researched.

The engine manufacturer Ziehl-Abegg has developed a wheel hub motor for city buses that is installed by several bus manufacturers (for example in the Ursus City Smile , a city bus with a fuel cell).

properties

The main advantage of electric wheel hub motors in vehicles compared to drive concepts with a central motor is the elimination of the classic drive train with the necessary components (manual) gearbox , cardan shaft , differential gear and drive shafts , depending on the design . Since their transmission losses are also eliminated, there is potential for increasing the efficiency of the entire drive system. Brake energy recovery can also be implemented with an electric wheel hub motor . In principle, drive concepts with wheel hub motors are single wheel drives in which the torque generated by the electric motor causes a tensile force at the wheel contact point of a wheel. Although a conventional vehicle with usually four wheels can also be driven on just one wheel, it makes sense, however, to provide at least one axle with an independently controllable wheel hub motor on the left and right wheel. With wheel hub motors, other vehicle concepts are possible that are practically impossible to implement with a conventional drive train for reasons of space. Since the drive is located directly in the wheel, vehicle concepts, for example, are conceivable in which a flat surface between the wheels can be used completely for the respective application. Furthermore, drive concepts with wheel hub motors offer significantly improved dynamics due to reduced rotational inertia of the drive train and much faster control of the drive torque, which can be used, for example, for driving safety systems and driving dynamics controls.

The increase in the unsprung masses - strictly speaking, these are masses sprung only by the tire - can have a disadvantageous effect, as a result of which the chassis tends to become less comfortable without changing its design. In comparison to central motors fixed to the body, the wheel hub motors are much more exposed to environmental influences (e.g. spray or jets of water, dust, salty media) as well as forces and accelerations acting in the wheel. Depending on the design, heat can also be introduced into the drive from the mechanical brake. Depending on the concept and the respective driving situation, this can mean an additional temperature lift for temperature-sensitive components such as the frequently used permanent magnets or the wheel bearings, which must be taken into account when designing the drive. The independent possibility of torque setting and control, which is inherent in the principle , leads to increased demands on the functional safety of the drives and the associated control devices.

Car example vehicles with wheel hub motors

1900 Lohner-Porsche

2004 Keio University Eliica

2005 Honda FCX Concept 2005

2010 Schaeffler ideas vehicle Schaeffler Hybrid based on an Opel Corsa

2011 “Fraunhofer e-concept car type 0 - Frecc0” from the Fraunhofer Society

2011 Volkswagen eT concept vehicle !

2011 solar vehicles like the SolarWorld GT

2013 Ford Fiesta concept vehicle with "E-Wheel Drives", this was the second generation of wheel hub drives from the supplier Schaeffler

2016 Concept of the Riversimple Urban Car

Concept vehicles with Hi-Pa Drive from PML Flightlink (until 2008), then Protean Electric (from 2009)
- 2006 "Mini QED" with 4 wheel hub motors, serial hybrid at the British Motor Show in London
- 2007 Volvo C30 ReCharge, plug-in hybrid with 4 wheel hub motors
- 2008 Ford F150 pick-up prototype shown at the 2008 SEMA Show in Las Vegas, battery-only vehicle
- 2010 Vauxhall Vivaro Plug-In Hybrid
- 2011 BRABUS Hybrid based on Mercedes-Benz E-Class
- 2011 Brabus High Performance 4WD Full Electric based on Mercedes-Benz E-Class, pure battery vehicle
- 2015 C-segment VW Golf Plug-In Hybrid

literature

Otto-Peter A. Bühler: Omnibus technology. Historic vehicles and current technology. Vieweg-Verlag, Braunschweig 2000, see wheel hub motor (pages 155 f., 161, 194, 196, 236, 249), ISBN 3-528-03928-0 .
Niels Fries: Practical manual for electric scooters. Mobility for an environmentally friendly future. Books On Demand Verlag, Norderstedt 2008, Chapter 5 Wheel Hub Motors , ISBN 978-3-8370-6062-1 .