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Ultimate Convenience Lock: DC Motor Applications

Electromechanical lock cylinders for automatically controlled locking function

Modern locking systems are not just designed for security and convenience but also have to consider the increasing role played by automation in building management. This is why purely manually operated lock cylinders no longer meet the necessary requirements in all cases. Particularly in areas where security is a sensitive issue, there are increasing demands for time-controlled locking and unlocking, automatic opening for authorized individuals or for functions controlled via the facility services control room. In addition, the door knob has to have a compact design to ensure a universal fit with a wide range of door hardware. Modern building control technology and integrated facility security systems increasingly call for electronically controlled lock cylinders. In many cases,however, there will also be a need to retain the existing manual operation. For applications that have to combine these two functions in one lock, EVVA has developed the new, compact EMZY motorized cylinder. The compact door knob design is suitable for a wide range of doors and door fittings. EVVA’s security experts have been working with microdrive specialist FAULHABER (in Germany) for the purpose of developing an electromechanical structure that is as compact as possible. A microdrive with high power density and compact planetary gearhead is the perfect solution when it comes to combining the benefits of electronic control and a rugged mechanical lock system.


Motorized doorknob in a modularsystem

For locking systems, ease of use and security aspects are important selection criteria. Automated door locks offer a wide range of functions, allowing the creation of a customized security concept. Integrated electronics, for example,allow installation of a time-controlled or pulse-triggered door latch. This setting can be integrated into a building security management system. As a result, areas with more stringent security requirements, such as laboratories, archives, R&D departments or restricted areas in general, can be rapidly equipped with access controls. However,even minor requirements, e.g. for the exterior doors of company premises to be accessible only at certain times, can also be met in this way. To ensure a consistent approach with regard to the over all security concept, it is important that the system is capable of being installed on any standard door if possible. In this respect, the security experts from Vienna were able to further reduce the size of their previous lock system. This means that the electromechanical lock cylinder now also fits modern glass doors with tubular frames. To achieve this, the entire unit had to be reduced to achieve a back setsize of no more than 35 mm(distance from center of door handle or keyhole to outside edge). As an additional innovation, the developers integrated a push-button for local operation. This dispenses with complicated wiring and installation of a separate door button. Naturally, automatic locking and unlocking triggered by motion sensors or access control are also possible. While many things are technically possible,they also have to be cost-effective. In this case, the new design allows for parts previously manufactured to customer specification, such as gearhead and driveshaft with special flange, to be replaced by standardized components. This simplifies logistics operations and saves costs. Despite the inexpensive design, the new system still meets the company's own high safety standards. For example, the motorized cylinder easily handles the guaranteed service life of 125,000 to 130,000 operating cycles at a torque of around one Nm per locking process. In addition,of course long-term influences, such as wear of the door closer, installation outdoors or in corrosive atmospheres such as indoor swimming pools, electroplating workshops or production facilities, have also been taken into account. Even anextended downtime without the lock activated does not impair its functioning.

Small, Powerful yet Undemanding.

The exacting requirement to combine power,efficiency and reliability in a small package is ideally met by compact bell type armature motor, with gearhead, supplied by FAULHABER subsidiary MINIMOTOR SA. The coreless rotor with skew-wound coil saves weight, and while smaller than conventional rotors, it offers comparable performance. Thanks to the rotor's low weight, the drive is very dynamic in the ramp-up phase, which shortens the closing times. As the drive is only in operation for a short time for the closing process, the wear on the commutator is not significant. On the contrary,the mechanical commutation allows reliable start-up even at the lowest voltages and functions. Of course, this process calls for specialist expertise. A special alloy for the commutators, and select brush materials, ensures that even under adverse ambient conditions, the contact resistance is extremely low and thus service life remains high. This is also the only modification necessary on FAULHABER's standard motor. The mechanical structure, bearing and surface coating are identical to those used in the standard range. As microdrives obtain their power from the rotational speed (output = rpm times torque), the motor's output speed has to be reduced to a value suited to the application by means of a planetary gearhead with matching diameter. At the same time, this increases the torque at the driveshaft. This means that any lock with a euro profile cylinder can be opened in less than a second. Even for the gearing, all standard design components were capable of meeting the stringent requirements of the security application in question. This also applies to the lifetime lubrication by select lubricants specially developed for high-efficiency microdrives. As a result, the over all efficiency of motor and associated gearing can be reliably maintained at the necessary high level over many years or hundreds of thousands of closing operations.

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