© Photo | FTE automotive

Big car, smaller emis­sions

The Controlled Piston from FTE helps vehi­cles save energy — using ECI motors from ebm-papst

Usually, when we think of V8 lorries and SUVs, the first thing that comes to mind is their size — and high fuel consump­tion. However, models are also avail­able that use little fuel rela­tive to their weight and horse­power — and thus also have lower carbon dioxide emis­sions. A Controlled Piston (CP) from FTE auto­mo­tive plays a crit­ical role in helping these vehi­cles save fuel.

Wher­ever automa­tion of hydraulic clutch oper­a­tions is required, the elec­tro­hy­draulic actu­ator unit provides high effi­ciency over a wide pres­sure and volume range. The prereq­ui­site for this is a highly accu­rate drive — such as the ECI motor from St. Georgen. We might say that it puts the “Controlled” in “Controlled Piston.” The ECI provides an ideal starting point for this appli­ca­tion, as it is highly dynamic and thus can move to the neces­sary posi­tions with great accu­racy.

High-preci­sion switching in lorries

The lorry’s gear shift mech­a­nism uses a ECI 76.45. The fully auto­mated clutch switches gears much more quickly, accu­rately and smoothly than previous models. This is not only more pleasant for the driver, it also saves fuel. For example, the gear shift mech­a­nism allows down­shifting at an early stage when driving uphill, making it possible to main­tain speed without using more petrol. Basi­cally, the engine actu­ates the piston of the CP only if the driver is actu­ally switching gears. In the old pneu­matic system, a constant supply of pres­sure had to be provided. This would not be possible without the fast and accu­rate acti­va­tion by the ECI motor.

However, the motor also has to with­stand some tough condi­tions: vibra­tion, heat and cold over endless kilo­me­tres. “Over its service life, the lorry goes through millions of gear shifts,” says Peter Metzger, Auto­mo­tive Sales Manager at ebm-papst St. Georgen, illus­trating the chal­lenge. “During this entire time, the motor has to with­stand extreme mechan­ical and thermal loads.”

The brush­less ECI motor is ideally suited to this task. The highly complex control system also has to with­stand these loads. The inte­grated elec­tronics are a joint devel­op­ment of ebm-papst and FTE. The centre­piece is called “flex tech­nology”: in a certain area, the printed circuit board can be bent by up to 180 degrees and folded together. This enabled FTE auto­mo­tive to inte­grate the elec­tronics into the CP module in a space-saving manner.

Smooth tran­si­tions in the hybrid

The intel­li­gent control system for oper­ating the CP in large sports­cars also presented a great chal­lenge. The result of the co-oper­a­tion of FTE and the devel­opers in St. Georgen: “Fully inte­grated, four-wheel drive compat­ible control of the entire power­train, which comes together in our control system — and is one-of-a-kind on the Euro­pean market.” In this car, the CP system actu­ates the cutout clutch and switches the different oper­ating modes.

The parallel full hybrid provides the cars with petrol-sipping power, but thanks to the intel­li­gent elec­tronics, this does not mean any less perfor­mance or driving dynamics. For this purpose, the control system uses either the combus­tion engine or the elec­tric motor or a combi­na­tion of the two. The elec­tric drive keeps the car moving with zero emis­sions at speeds up to 50 kilo­me­tres per hour in city traffic, but also main­tains the car’s speed while cruising on the motorway. If the driver spon­ta­neously needs to use the full engine output, the combus­tion engine and elec­tric motor provide a simul­ta­neous boost. The indi­vidual oper­ating states have to be closely matched to each other. This is carried out by the CP, an intel­li­gent control system that shifts gears so smoothly that the car’s occu­pants do not even notice it.

At the heart of the hybrid CP, an ECI 56.45 actu­ates the piston. The “little brother” of the lorry motor, it is located in the wheel well along with the module, remaining quiet and incon­spic­uous. “During devel­op­ment, we tried out different lubri­cants to decrease the already low noise even more,” reports Metzger. Thus the small, smart drive not only helps the vehi­cles attain lower emis­sions, it also makes driving more fun!

Controlled Piston (CP)

The CP elec­tro­hy­draulic actu­ator from FTE auto­mo­tive is an actu­ator unit for use in clutches and hybrid appli­ca­tions. It enables highly dynamic hydraulic appli­ca­tions to be imple­mented in the area of mobile drives. The central element of the CP is the ECI brush­less DC motor from St. Georgen. It drives a recir­cu­lating ball screw spindle that moves a hydraulic piston for pres­sure gener­a­tion and volume displace­ment.
There­fore, the CP provides the following advan­tages:
• High overall effi­ciency
• High dynamics
• Inno­v­a­tive inte­grated elec­tronics
• Low pulsa­tion
• Low noise level

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