Hybrid Drives - Wacker Chemie AG

CREATING TOMORROW´S SOLUTIONS

Hybrid Drives

Electric Vehicles Come of Age

Hybrid drives, which use a powerful, compact electric motor to supplement the internal combustion engine (ICE), represent a first step on the path to emissions-free electric vehicles. Most production hybrid vehicles are of the parallel type. And parallel hybrids are also the focus of Schweinfurt-based ZF Sachs AG, a leading manufacturer of drive and chassis components.

Powertrain of the Audi Q5 hybrid quattro: because the Audi Q5 hybrid quattro is a full (strong) hybrid, it is capable of driving in all-electric mode for stretches at a time. The electric motor, which delivers 40 kW, works variously as drive motor, generator or starter motor, depending on driving conditions and requirements.

“Parallel hybrids are relatively inexpensive and the easiest way to implement them is to modify conventionally powered models. The important thing is to integrate the hybrid drive into the existing vehicle design as simply as possible,” says engineer Frank Kewes, who oversees the construction and operation of the hybrid module production plant at ZF Sachs AG.

Production robots at ZF Sachs.

High Temperatures: With Silicones, No Problem

Naturally, high power densities create high temperatures inside the electric motor. Temperatures can reach 200 C, particularly around the current carrying stator windings. “These high temperatures necessitate the use of silicone products,” says Frank Kewes. “We decided to use silicones from WACKER.” ZF Sachs’ rotor line utilizes SEMICOSIL®988, a silicone adhesive, and its stator line ELASTOSIL®RT 705 silicone rubber and SILRES®H62C silicone resins. These two steps provide the motor with perfect moisture and water protection, ensuring that it stays permanently safe and reliable: “The motor won’t even short-circuit when dipped in salt water – it simply keeps on working,” adds Kewes.

DynaStart®electric motor for cars. This starter-generator was developed by ZF Sachs specifically for parallel hybrids.

For compact, high-performance electric motors, silicones are the material of choice because of their ability to bond, seal, damp vibration and electrically isolate. Unlike similar organic materials, crosslinked silicone products remain fully functional when exposed to a very wide range of temperatures over the long term.

The Fascination of Chemistry – WACKER’s Audio Magazine

Electric Start-Stop Technology

The start-stop technology of a hybrid drive automatically turns off the engine when the vehicle stops, e.g. when the driver takes his foot off the gas pedal at red lights. The engine restarts automatically when the driver steps on the pedal again. The electric motor takes no more than 0.2 seconds to get the engine up to the necessary starting speed. The driver barely notices any delay at all, and there is no vibration or starter-motor sound. Start-stop technology saves on fuel and adds to comfort and convenience.

Engine-Assist

When the vehicle accelerates during startup or when passing other cars, the electric motor supplements the internal combustion engine (ICE). In parallel hybrids, the motor and the engine complement each other, both driving the same shaft and contributing to the total torque. Unlike an ICE, an electric motor develops particularly high torque at low speeds. As the speed increases, the torque developed by the ICE increases while that of the electric motor decreases. Engine-assist makes parallel hybrid vehicles very dynamic – both power sources develop full torque at just 1,000 revolutions per minute. It can also be used by automakers for downsizing – smaller ICEs translate to lower fuel consumption.

Recuperation of Braking Energy

Recuperation is the technical term for energy recovery. In hybrid vehicles, the electric motor can harness some of the energy expended on braking, and so recover energy that was previously used to accelerate the vehicle and would otherwise be lost as waste heat. To this end, the electric motor operates as a generator, converting the mechanical energy generated during braking or cruising (supplied by the rotation of the drive shaft to the electric motor) into electrical energy, which is stored in the battery. Energy recuperation substantially lowers fuel consumption and carbon dioxide emissions.

  • Share
  • TOP
  • Print