DE3235773A1 - Electrical starter - Google Patents

Abstract

The invention relates to an electrical starter motor which carries in each case at least one short-circuit ring parallel to its field windings on the pole shoes, which short-circuit rings cause the build-up of the torque to be delayed during starting.

Description

Electric starter

The invention relates to an electric starter, in particular for the internal combustion engine of a motor vehicle, which is used as an electric motor on pole pieces has arranged field windings and an armature usually connected in series therewith, the electrically preferably via a magnetic switch with a direct current source are connectable.

Well-known electric starter motors, mostly direct current main circuit motors, have a high starting torque, the gear shafts, gears and especially the Heavily loaded freewheel. These loads often lead to the breakage of transmission parts. There is play between the gears and the elasticity of the shafts and gears cause an increase in torque when starting. These endangered mechanical Components must therefore be oversized.

A two-stage circuit has therefore been proposed, with the starter Can be switched on via a series resistor, which after a short running time of the starter is automatically bridged. These measures result in the desired start-up characteristics of the starter. Aside from the expense of an extra resistor and one Starter protection against direct switch-on and the associated reduction the reliability, this arrangement has the disadvantage that in the event of an error The series resistor can burn up and set the engine on fire.

The invention is based on the object of an electric starter of the type outlined above with the simplest possible means to improve that this emits a delayed build-up torque when switched on.

The object is achieved according to the invention in that the starter has at least one short-circuit ring linked to the magnetic circuit.

By this measure, the magnetic field of the starter when it is switched on built up delayed, which also results in a delayed build-up of the torque Has.

In a further development of the invention it is provided that the or

the short-circuit rings are arranged on the pole pieces parallel to the field winding are. It is advantageous if the short-circuit rings on the pole pieces to the the anchor facing ends are arranged.

Finally, it is particularly useful to save space, when the contact surfaces of the short-circuit rings on the pole pieces closely matched their shape are.

The invention is illustrated below with the aid of an exemplary embodiment described in more detail with reference to the drawing.

The only illustration shows a simplified section through the housing, the two field magnets and the armature of a starter motor according to the invention.

The illustrated electric starter motor 1 is in a housing 2 opposite two pole shoes 3 and 4, which are preferably not in the housing 2 Screws shown are supported. An anchor is located between the two pole pieces 3, 4 5 rotatably mounted. Both pole shoes 3, 4 each carry a field winding 6, their individual ones Head have a relatively large cross-section. It also sits on each of the pole pieces 3, 4 on the side facing the armature a short-circuit ring 7 made of a highly conductive Material. The short-circuit rings 7 are to achieve a compact design of the Starter motor 1 of the shape of the pole pieces 3, 4 closely matched.

For a DC motor, the torque is the product of Armature current times excitation field is proportional.

Md - Ia. B. If one achieves so by suitable means that the build up one or both values Ia or B with a delay, the torque builds up too delayed on.

According to the above proposal, with simple means, namely with the help of the short-circuit rings 7, achieved that the excitation field built up with a delay so that the starter motor starts with a relatively small torque. Blank page

Claims (4)

Claims 9 Electric starter, in particular for the internal combustion engine of a motor vehicle, the field windings arranged as an electric motor on pole pieces and thus has an armature which is usually connected in series and which is preferably electrically can be connected to a direct current source via a magnetic switch, characterized in that that the starter (1) has at least one short-circuit ring linked to the magnetic circuit (7). 2. Starter according to claim 1, characterized in that the or the short-circuit rings (7) on the pole pieces (3 or 4) parallel to the field winding (6) are arranged. 3. Starter according to claims 1 and 2, characterized in that the short-circuit rings (7) on the pole pieces (3 or 4) on the armature (5) facing Ends are arranged. 4. Starter according to one of the preceding claims, characterized in that that the contact surfaces of the short-circuit rings (7) on the pole pieces (3 or 4) their Shape are closely matched.