DE603394C - Self-starter, especially for larger electric motors - Google Patents

Description

Self-starters, especially for larger electric motors It is known To start electric motors by means of centrifugal devices. With smaller machine units such centrifugal devices have been placed directly on the engine axis, with so the contacts take part in the rotation of the motor. Apart from the fact that here Usually the armature is switched, this method is used for larger machine outputs out of the question because of the extensive starting equipment. Used for such systems one today mostly self-starters working with additional motors.

The suggestion has now been made, including greater machine outputs cope with centrifugal starters. In particular, this proposal provided for to drive the centrifugal device from the motor shaft by means of a belt, wherein in the starter end position, a magnetic device was actuated, which the The belt of the drive of the centrifugal device should move onto the loose pulley.

Apart from the technical difficulties that arise when if you want to disengage a belt drive by means of a magnet, this suggestion has been made two other disadvantages.

First, in this starting procedure, the magnet assembly is with the engaged Motor put under constant current, ivas large dimensions of the magnet and besides high power consumption or the need to use expensive economy circuitry has the consequence.

Second, this proposal has the disadvantage that if the Current the magnet falls out and the starter via the centrifugal device still once it is uselessly coupled to the decelerating engine.

In contrast, the invention relates to a self-starter. which one the engine drives a centrifugal device via a disengageable clutch, and is that the controlled by the centrifugal device starter in his End position of an electromagnetic friction clutch for the centrifugal device turns off. This ensures, on the one hand, that the magnet is always only briefly is switched on, so it does not need to be rated for continuous load while on the other hand, if the current is absent, the coupling device does not need to be restored again - is engaged because the magnetic coupling remains de-energized.

The new starter is possible with different starting devices, and the two figures show two such examples.

Fig. Z shows a direct current electric motor with a roller starter. , a is the motor to be started, b a magnetic coupling, c the centrifugal device, d the roller starter. This system works as a self-starter after closing the main switch e. The motor a nü, mt when starting via the magnetic coupling b, the centrifugal device c, which actuates the roller switch. In the switch end position: the magnet i receives current and places a pawl g in a cam disk f, while the magnetic clutch b is switched off. The engine is now in operation. When the current is switched off or there is no current, the spring h lifts the pawl g out of the cam disk f, whereupon the shift drum d under the influence of some kind of retraction before. direction returns to the zero position.

Of course it is also possible to lock the starter in the End position instead of the cam disk f the usual box disk of the controller to use.

Fig. 2 shows a similar system for a three-phase motor. In this case, the box device described can be replaced by a brush lifting device. Parts a, b, c, d, - are the same as in Fig. I. k is a brush which is lifted by the magnet m and placed by the spring L. n is the slip ring belonging to this brush. When starting, the brush rests on slip ring n under the action of the spring L. In the switch end position, the magnet m lifts the brush off. The starter d does not need to be a roller starter in this case.

Claims (1)

PATr, NTANSPRUCI3: self-starter, especially for larger electric motors, whereby the motor drives a centrifugal device via a disengageable clutch, characterized in that the starter controlled by the centrifugal device (c) (d) in its end position an electromagnetic friction clutch (b) for the centrifugal device turns off.