Electromechanical brake
Electromechanical brake (EMB) is a term from mechanical engineering.
It describes a design variant in which either the braking impulse, the transfer of the required energy or the actuation of the brake elements (e.g. brake shoes) are carried out electrically.
Electromechanical brake systems are in principle used in all applications in which hydraulic, pneumatic or mechanical brake systems are currently used. Its use as a parking brake in vehicle construction is now widespread, see also: Brake-by-Wire and parking brake .
As an example: braking a wind turbine (WEA)
Brakes in wind turbines are an essential part of the safety concept of these systems. On the one hand, they are used as a rotor brake to protect the system from overspeed or to brake and shut down the system for maintenance purposes. The braking force can be applied actively or passively (e.g. by spring-loaded brakes ).
On the other hand, yaw brakes are used: the nacelle of a wind turbine is mounted on the tower so that it can be rotated 360 ° so that the rotor blades are always optimally positioned in the wind. When the wind direction changes, the brake releases the clamping connection between the tower and the nacelle and the so-called azimuth drives drive the nacelle into the wind. In order to protect the drives, the azimuth brake is applied again and the drives can be switched off again.
Another important component in the wind turbine safety concept is the so-called rotor lock. The rotor lock is a mechanical locking bolt which blocks the rotor and prevents the system from spinning (from the English: lock = locking, locking. To lock sth. = Locking something). Its use is mandatory for maintenance work on rotating parts of the rotor.
Electromechanical brakes in a wind turbine
With electromechanical brakes, the braking force is generated directly on the brake caliper via an electric motor and a motion gear. The electric motor only needs to be energized for the time the braking force is built up. The braking force is retained without additional energy being supplied until the command to release the brake is applied. This can take up to several weeks. The structural design of such brakes allows a very compact design with few components. Electromechanical brakes are maintenance-free until the end of the useful life of a wind turbine. Only worn brake pads need to be replaced. The electromechanical brake is now considered the most economical and reliable braking system for wind turbines.
Many (especially older) wind turbines still have hydraulic rotor or azimuth brakes. However, these have various disadvantages:
- They are prone to failure and often have oil leaks.
- Leaking brake calipers, worn valves or defective hydraulic hoses are often seen problems that can lead to a loss of braking force or even system failure. In addition, a functioning hydraulic unit is always required.
- Oil changes, oil disposal, hose and seal changes must be carried out at regular intervals. This causes wind turbine downtimes and significant maintenance costs - especially for offshore systems that are difficult to reach .
Therefore the electromechanical brake technology described above was adapted for wind power plants.