Avail­ability, speed, flex­i­bility, and often compact­ness as well, are among the most impor­tant require­ments for systems for the in-house move­ment of mate­rials. The solu­tions typi­cally employed to date reach their limits here. They require many different compo­nents, space usually cannot be opti­mally utilized, reac­tion times often leave some­thing to be desired, and the solu­tions are scal­able only under limited circum­stances. Two exam­ples – a sorting system and a roller conveyor for pallets – illus­trate the poten­tial for improve­ment in new systems, upgrades or expan­sions powered by compact elec­tric drives with inte­grated control elec­tronics.

Effi­cient sorting and diverting

The rollers on a sorting gate or a cross­belt sorter (Fig. 1) have thus far been driven via a trans­mis­sion, toothed belt and cam by an AC motor controlled by a vari­able frequency drive, with a pneu­matic cylinder oper­ating the divert. Two sensors are needed for the pneu­matic system’s end posi­tion detec­tion. In addi­tion, there are the pneu­matics controller and the rela­tively expen­sive compressed air supply.

Figure 1: In a sorting gate or a cross­belt sorter, the intel­li­gent roller drive is installed right in the feed rollers and there is room in the frame for the compact divert drive. (Photo | nullplus/Adobe Stock)

With compact and intel­li­gent elec­tric drives, this automa­tion problem can now be solved much more elegantly, with fewer compo­nents and without compressed air. The roller drive is installed right in the feed rollers and there is room in the frame for the compact divert drive. Better use is thus made of the avail­able space since there are prac­ti­cally no protru­sions. The belts can be posi­tioned closer together hori­zon­tally or verti­cally or posi­tioned close to the floor.

Instal­la­tion is also simpli­fied, in partic­ular because no compressed air lines need to be mounted and no mechan­ical force transfer elements such as toothed belts are needed. In addi­tion, only one sensor is needed for posi­tion detec­tion at the divert and, if neces­sary, a single drive can shift the divert in two direc­tions.

With compact and intel­li­gent elec­tric drives, this automa­tion problem can now be solved much more elegantly, with fewer compo­nents and without compressed air.

The clas­sical arrange­ment needs a second pneu­matic cylinder for this, also with two sensors for end posi­tion detec­tion. So for two-way diverts, it is even possible to dispense with three sensors. This is also of interest for refits because the EC drive can, with appro­priate para­me­ter­i­za­tion, act as a pneu­matic lift cylinder and is thus back­ward compat­ible.

Figure 2: Intel­li­gent drives are also used in clas­sical pallet conveyor systems – with fewer compo­nents and without compressed air. (Photo | chesky/Adobe Stock)

Pallet trans­port without higher-level control system

A rethink is also worth­while for clas­sical pallet conveyor systems (Fig. 2). If intel­li­gent drives – drives that commu­ni­cate directly among them­selves – are added to the indi­vidual segments, a higher-level control system is no longer needed for pres­sure-free trans­port (Fig. 3). The sensor signal for deter­mining the pallet’s posi­tion is read directly into the compact drive; here, too, the drives can be installed in the rollers and there are no protru­sions and the number of required compo­nents is reduced. Instead of a higher-level control system and a vari­able frequency drive, AC motor and sensor, only an intel­li­gent compact drive with sensor is needed for each segment.

Figure 3: The intel­li­gent drives in the indi­vidual segments commu­ni­cate directly among them­selves and ensure pres­sure-free trans­port of the pallets.

Inte­grated elec­tronics for motors from the modular drive system

The compact EC drives from drive specialist ebm-papst owe their intel­li­gence to their inte­grated K4 control elec­tronics, which include a compact, power output stage and can run the motor down to stand­still using a field-oriented closed-loop control module. The K4 control elec­tronics make it possible to tailor a drive to an application’s require­ments. Three main oper­ating modes are possible, with the motor working in speed, posi­tioning or torque mode. The fully inte­grated control elec­tronics also provide several analog and digital inputs and outputs, which can be config­ured via an RS485 inter­face. The drive’s func­tion­ality during oper­a­tion can also be controlled by moni­toring numerous quan­ti­ties such as voltage, current, speed, temper­a­ture, etc.

Figure 4: The intel­li­gent drives in the indi­vidual segments commu­ni­cate directly among them­selves and ensure pres­sure-free trans­port of the pallets.

Depending on appli­ca­tion require­ments, the powerful control elec­tronics can be inte­grated in various external or internal rotor EC motors. The different series are designed as modular systems so that an appro­priate solu­tion can be found for every require­ment. Output power reaches 120 watts for the elec­tron­i­cally commu­tated VARIODRIVE Compact external rotor motors (Fig. 4) and 750 watts for the ECI series of internal rotor motors (Fig. 5), making trouble-free trans­port possible even for very heavy pallets.

The drive systems can be quickly and flex­ibly adapted to the specific task at hand thanks to their modular design. In other words, they can be combined with trans­mis­sions, encoders and brakes as needed. Several thou­sand vari­ants are possible in all, with desig­nated preferred types ready to ship within 48 hours.

The compact EC drives from ebm-papst owe their intel­li­gence to their inte­grated K4 control elec­tronics.

The motors also impress with their length. The active compo­nents (wound stator and rotor equipped with magnets) of the internal rotor motors, for example, are just 20, 40 or – in the most powerful variant – 60 mm long, meaning they can be easily accom­mo­dated in the limited space avail­able in the rollers and system frames. Various trans­mis­sion modules are avail­able to raise the output torque to the level required by an appli­ca­tion.

Along­side plan­e­tary and spur gears, space-saving EtaCrown crown gear­heads based on inno­v­a­tive crown-gear tech­nology can also be supplied, for example. If the appli­ca­tion in ques­tion demands holding or safety brakes, such as for safely main­taining the posi­tion of lifting equip­ment in the event of a power supply failure, modules with perma­nent-magnet or spring-oper­ated brakes can be added to the drive unit. Redun­dant encoder systems are possible for safety-rele­vant appli­ca­tions.

Figure 5: With diam­e­ters of 42, 63 and 80 mm, the EC internal rotor motors cover a power range from 30 to 750 watts and can be quickly and flex­ibly adapted to the task at hand thanks to their modular design.

The drive systems fulfill the require­ments of protec­tion class IP54 while also offering flex­ible means of elec­trical connec­tion. These include industry-stan­dard connec­tors, in which the radial angled plug with bayonet connector can rotate and engages auto­mat­i­cally. An axial plug is avail­able for space-crit­ical appli­ca­tions; as an alter­na­tive, a preassem­bled cable connec­tion is also possible.