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Brushless motors (DC machine)

A DC machine refers to an electric motor which is powered by direct current or a generator that converts mechanical energy into reverse AC voltage and demodulates it. In some cases, a device can perform both functions.

Built-in motors

In the case of built-in motors the active parts of the motor – stator with a coil and rotor with a shaft – are built into the client’s housing or the machine part.

Direct drives

Direct drives are drives in which the electrical machine and the machinery are directly connected. The motor is designed in such a way that straight away, it has the speed of the machinery. No gearbox is needed.

Typical examples for direct drives include grinding machines, fans, water pumps, linear drives and torque motors.

Drive systems

In the field of technology, a drive refers to the constructive unit that drives power conversion by means of a machine. Often, there is a motor with the gears which are necessary. There are rotary drives and linear drives.

Drum motors

Drum motors are modern drives which combine the gear motor and drive drum in a fixed unit. Drum motors were developed as a drive for belt conveyors. Through continuous development and the use of modern materials, drum motors are also used for different applications. As a general rule, a drum motor can be used wherever a drum is driven with an external gear motor.

Electric motors

Electric motors are electromechanical transducers that convert electrical energy into mechanical energy. In electric motors, the power that is exerted by a magnetic field on the current-carrying conductor of a coil is converted into motion. As such, electric motors are the opposite of generators. Electric motors usually generate rotary motion, but they can also perform translational movements. Electric motors are used to drive various machinery and vehicles.

Fountain pumps

Submersible pumps have been developed around water-filled submersible motors. Water-filled submersible motors were developed in 1928 by Mr. F.W. Pleuger. In the same year, Pleuger’s submersible pumps were first used in the construction of the Berlin underground railway in order to lower the groundwater. In the course of the company’s development, many other breakthroughs were achieved. When talking about submersible pumps, we often refer to ‘Pleuger pumps’ even today.

Fountain pumps are suitable for:

Freely programmable direct drives

Synchronous servo-motors, torque motors, linear motors. These are operated via an electronic controller. This allows the speed, torque or position to be selected freely.

Frequency convertors

These are devices which are based on electronic semiconductor units which operate in a switching operation, i.e. only in an on-state or off-state. In variable three-phase drive systems, they have the specific task of generating (usually) three-phase voltage with a variable frequency and voltage amplitude for feeding the AC motor from single-phase or three-phase mains AC voltage with a constant frequency and amplitude. Previously, networks of different frequencies were coupled via rotating frequency convertors. However, in convertor stations for traction power, mechanical systems are still used.

Gear motors

A gear motor is a combination of a motor (usually an electric motor) and a gear system. It ensures that the output shaft (mostly) turns with less speed, but considerably more torque than that of the motor.

Linear motors

According to the principle, each type of motor which can be realised as a rotary electric motor can also be realised as a linear motor in an elongated arrangement. In their usual design as a synchronous motor or an asynchronous motor, a linear motor is only made up of two parts, a coil package and a secondary part. There are flat and cylindrically-designed magnet-operated linear motors which are air-cooled and water-cooled. These have different management systems and form the drive for the translatory direct drive. In a way which involves low levels of wear and tear and oscillation, they allow the direct supply of power to longitudinally-moving machine parts, without the prior conversion of a rotating motion.

Motor geometry

Motor geometry represents the most important geometric characteristics and dimensions of classic motors.

Pumps

Liquids, gases or mixtures are circulated using a pump. For this, the work of the drive is converted into the kinetic energy of the medium. As such, pumps are fluid energy machines.

Rotary tool motors

When used in electrical turbochargers for example, there are motors which reach over 100,000 min-1. This is achieved using a power supply with a frequency convertor with a supplied frequency of several hundred to 1000 Hz. The motor is smaller compared to a standard motor with the same power. In part, the rotating parts have to withstand significant radial acceleration (centrifugal forces).

Further examples

Saw motor

Saw motors are machines which power circular saw blades using electric motors. Saw blade diameters can range from approx. 20 cm to approx. 500 cm.

Servo-convertors / Servo-drives

Servo-drives contain a servo-motor, the servo-controller with power electronics, a control unit and, as the case may be, the gear for speed adjustment or for converting the rotary motion into a linear motion. The servo-convertor supplies the servo-motor with electricity. In addition to the power electronics, the servo-controller contains a highly dynamic control unit for power, speed and position. In addition, the servo-convertor includes evaluation electronics for evaluating the motor’s position sensor and an interface for communicating with the machine control unit.

Shrunk-on-disc motors

A shrunk-on-disc (pancake) motor is an electric motor, where the rotor has the shape of a disc (this is why the motor is also known in English as a ‘pancake motor’). In its most familiar design, the current-carrying coils are located in the housing. Disc rotors are easily recognised by their design, which is unusual for other electric motors (the diameter is greater than the length).

Spindle drives

Spindle motors are convertor-controlled three-phase asynchronous motors or synchronous motors for driving machine tool spindles for grinding, milling and engraving. They are also used in automated drilling applications. Spindle motors are also known as the driving elements for linear actuators. In synchronous motor and step motor designs, they are used in conjunction with an integrated threaded spindle for direct converting a rotational movement into a translational movement.

Synchronous motors

A synchronous motor is a synchronous machine operated as a motor, in which a constantly magnetised rotor is synchronously picked up by a rotated magnetic field in the surrounding stator. The moving synchronous motor has a movement which is synchronous to the alternating current – the speed is thus linked via the number of pole pairs with the alternating current frequency.

Synchronous shrunk-on-discs

see Shrunk-on-disc motors

Tool changers

In a machining centre, a tool changer is a mechanical device for automatically exchanging tools or process-related aids. Using the tool changer, tools are exchanged between the tool racks and the machining spindle and vice versa. The exchange process takes place using single or double claws or from the rack to the spindle (pick-up-exchanger). The tool changer speed is measured by the time it takes for a tool to be changed.

Torque motors

Torque motors are rotary drive elements for the direct drive. In modern designs, these are brushless synchronous motors with multi-pole permanent magnet excitation in the internal or external rotor embodiment. They are especially used in the machine tool industry to replace hydraulic and conventional electric drive structures consisting of an electric motor and a gear unit. They are designed for high torques (up to several thousand Nm) and low speeds and their mechanical design is such that they can be easily integrated into the body of mechanisms and machines which need to be driven.

Water-cooled motors

Electric motors are traditionally cooled using air. In very large machines, liquid cooling has already been used for some time. However even the lower power range (<50KW), liquid cooling can bring great benefits.

The lost heat from the motor is fed away by the coolant and as such, does not impact the immediate surroundings. In particular, this is a great advantage in:

• Precision machines
• Unfavourable installations (no air circulation)
• High ambient temperatures
• Climatised rooms