DE202004017173U1 - Four-rotor helicopter with electric drive has no reduction gearboxes between motors and rotors and motors are electronically commuted external rotor electric motors - Google Patents

Abstract

The helicopter has an electric drive, whereby each rotor is driven by its own electric motor. The 4 rotors are arranged on the corners of a rectangle in plan view. No reduction gearboxes are present between the motors and the rotors and the motors are electronically commuted external rotor types.

Description

State of technology

Electric helicopter, the above all axes to be controlled can be designed mechanically simple if you have 4-rotor design and the speed of the 4 rotors to be controlled. Then namely to the usual one Mechanics for control (collective and cyclic blade adjustment, Flaps in the rotor beam etc.) can be dispensed with. Mechanically moved Parts are limited to rotating drives.

Previous 4-rotor electric helicopters are with reduction gears between motors and rotors. So that can be comparatively size Rotors are driven, which has a positive impact on energy efficiency affects (low circular area load).

adversely the fact is that the transmission is additional Weight and mechanical loss entails what energy efficiency again reduced. Gear transmissions are typically used. Wear occurs on gears and shaft bearings. As wear progresses, gears can also suddenly fail, e.g. B. by broken teeth or eating. Consequence: the helicopter crashes from.

As Drive motors for 4-rotor helicopters have so far only been used with relatively high-speed internal rotor, the required torque for efficient rotors only over can provide a transmission.

Of course you can too internal rotor be designed for low speeds. To the required torque To produce in direct drive, however, must be a relatively large and so heavy engine chosen be what drives up the power requirement. This way is therefore less promising.

problem

The Invention was based on the problem of a mechanically very simple, robust and efficient 4-rotor electric helicopter to create the ideally except the storage of a single shaft for motor and rotor no more wear parts adduced.

invention

This Problem is solved with the invention according to claim 1.

advantageous Effect and presentation of the invention

interesting Applications for 4-rotor electric helicopters are mainly small drones, camera carriers and Measurement platforms.

The Development of small electric motors is progressing steadily. That applies especially for permanent magnet DC motors with electronic commutation. Thanks to new designs (eg "LRK motor" from Lucas, Retzbach and Kühfuß in the DMFV brushless primer of the German Model Aviation Association e. V., Bonn) and improved magnetic materials become power density, specific Torque and efficiency increased. The associated one too Power electronics contribute to this at; new compact, electronic components promote miniaturization.

Newly developed, high-torque, slow-running external rotor motors allow direct drive comparatively large and therefore more efficient rotors. The rotor can, for example, directly on the motor shaft. So that the motor shaft is at the same time also rotor shaft. So enough z. B. 2 deep groove ball bearings to support the shaft with low friction.

electronic commutated motors have no brushes and are therefore up on the storage wear-free.

The saved weight of the transmission and the lack of friction losses energy efficiency is very beneficial. Especially with the electric drive this is important because the energy density of electrical energy storage is rather small. The efficiency gains can be used for longer flight times and higher Payloads.

More useful Side effect: If the gearbox is omitted, the gearbox noise is also eliminated. Through the moderate speeds, the drives are very quiet.

• 4 Rotoren; Durchmesser: 340 mm, Drehzahl: 2000 1/min,
• Abflugmasse des Fluggeräts: 600 g,
• Masse eines Motors: 30 g,
• Leistungsbedarf für alle 4 Antriebe: 40 W,
• Flugzeit: 60 min mit Lithium-Polymer-Antriebsakku (zum Vergleich: derzeitiger Dauerflugweltrekord für Elektrohubschrauber liegt bei 70 Minuten).

An embodiment of the invention has the following data:

• 4 rotors; Diameter: 340 mm, speed: 2000 1 / min,
• Take-off mass of the aircraft: 600 g,
• Mass of a motor: 30 g,
• Power requirement for all 4 drives: 40 W,
• Flight time: 60 min with lithium polymer drive battery (for comparison: the current world flight record for electric helicopters is 70 minutes).

Claims (1)

Four-rotor helicopter with electric drive, each rotor is driven by its own electric motor, the 4 rotors are arranged in plan view at the corners of a square, characterized in that there are no reduction gears between motors and rotors and the motors are electronically commutated external rotors.