DE161459C - - Google Patents

Description

IMPERIAL

PATENT OFFICE.

DC machines in which, in addition to the main brushes, other brushes are connected to a Partial voltage, e.g. B. to half the voltage, are intended to reduce the Sparking on the latter brushes should be set up so that those under the same short-circuited turns no or no significant induction by the Are subject to magnetic field. The present invention gives a new solution to this problem.

The essence of the invention results from the schematic representation in Fig. I, which shows a two-pole machine unrolled in the known manner. As can be seen from this figure, the length of the pole arcs is less than half the pole pitch. The armature winding α is designed as if the armature should be used in a four-pole machine. The winding step of the winding, for example designed as a loop winding, is only six respectively. five groove pitches, while the total number of grooves is 25. At the commutator c, the main brushes b ^l and b ³ grind at the points of greatest voltage and in between the partial voltage brushes U ¹ and b *.

If one follows a single turn as it moves from left to right, from the moment it leaves the brush b _L , one finds that a rectified electromotive force is induced in this turn until it comes ^{below έ 3;} for at the beginning the number of positive lines of force which penetrate the winding decreases and later the number of negative ones increases. The electromotive force is different in the different positions, namely at its greatest when one side of the turn passes a pole and the other side lies in the space between the two, where no lines of force come because of its great width. However, if both sides are in gaps, no electromotive force is induced in the turn. This is the case when the turn is below b ¹ and b ^s , but also when b ² and £> ⁴ , with both sides in the same space. The voltage from web to web thus changes in the manner shown by the viewing line in FIG. 2, while the total voltage is shown by FIG. 3.

The machine described above met so the condition set. An advantage of the same over others for the same purpose chasing machines is that because of the small winding pitch of copper for the end connections is saved.

4-7 are some embodiments of the machine for different uses shown.

Fig. 4 shows the machine as a three-line machine. The center conductor is fed jointly by equi-potentials brushes & ² and b * , which are short-circuited for this purpose. The excitation takes place, for example, by composite winding. The series winding must be chosen to be relatively strong. If you follow the course of the current in the individual

Claims (4)

Anchor wires, which can easily be done with reference to Fig. Ι, one finds that although the current taken from the brushes bl and bs and flowing through the outer conductors does not generate an opposing field, but only a transverse field, on the other hand that in the short-circuit connection of the brushes b '2 and b * flowing current, which comes from the rotation in the transverse field, an opposing field, which is to be canceled by the series winding. In Fig. 4, the brackets indicate how the individual anchor wires interact to generate these fields. If the machine is used as a motor, different speeds are obtained, depending on whether the current is fed through the main brushes or one of them and the partial brushes. Particularly when connected to a three-wire network, very different speeds can be achieved by simply switching the connections, apart from the fact that regulation can also be carried out by other means, such as resistances or changing the number of field turns. In FIG. 5, such a motor is connected to a three-wire network, for example via a roller switch d. When the switch is in position I, the field coils are connected to the outer conductors ι and 3, b1 to the center conductor 2, ba to 3, so the field to the whole, the armature to half the mains voltage; this gives the lowest speed. In position II, b1 is connected to 1, i.e. the armature is connected to the entire mains voltage. So the speed doubles. In position III, b'2 and £ 4 are short-circuited and applied to 3 at position bz; the speed doubles again. In the last position "IV, the armature circuit remains unchanged, while the field is applied to half the voltage; this increases the speed even more, and indeed up to twice as much, depending on the magnetic saturation of the motor. The voltage between Brushes b2 and Z> 4 are proportional to the transverse field, i.e. indirectly to the current drawn from brushes bJ and b9. If brushes ö2 and bl are short-circuited, the current flowing between them and therefore the opposing field is very large. The machine can therefore be used as a generator with a strong armature reaction as a generator for constant current strength, whereby the field must be excited separately (Fig. 6) In this case, the current flowing through b2 and & 4 supports the stator field r can excite this current (Fig. 7). Sponsorship τ claims: 1. . DC machine with partial voltage brushes, in which the under the latter short-circuited turns are at points of low induction, thereby characterized in that the pole arc length is less than half the pole pitch and that the armature for twice the number of poles is wrapped. 2. Embodiment of the machine according to claim 1 as a motor with different Speeds, characterized in that the two alternate Main brushes or one of the same and the partial voltage brushes connected to the mains will. 3. embodiment of the machine according to claim 1 as a motor with armature excitation, characterized in that the partial voltage brushes are short-circuited with one another and the field poles are not wound. 4. Embodiment of the machine according to claim 1 as a generator for constant Current intensity, characterized in that the partial voltage brushes are short-circuited with one another and the field poles through are energized by an external power source. 1 sheet of drawings.