DE102006030721A1 - Electric motor with speed setting - Google Patents

Abstract

The present invention relates to an electric motor having a number n of poles (4a-4d), where n is even and greater than 2, and a number m of brushes (1, 2), with 2 <= m <= n, in which a number r of additional brushes (3) for speed setting with 1 <= r <= n / 2 is provided.

Description

State of the art

The The present invention relates to an electric motor with speed setting.

The use of a third brush for speed adjustment in 2-pole motors is known eg in wiper motors. Such a motor is schematically in 3 shown. The direction of rotation of the here provided with twelve commutator laminations anchor 5 is to the right, the engine has two opposite poled magnetic poles 4a . 4b , a first brush lying at 0 ° 1 , a second brush lying at 180 ° 2 that is the first brush 1 is arranged opposite, and one to the first brush 1 against the direction of rotation of the anchor 5 shifted arranged third brush 3 on. In the low speed stage, the two opposite brushes, ie the first brush 1 and the second brush 2 energized. The third brush 3 is de-energized. In the high speed level become the third brush 3 and the second brush 2 energized. The brush 1 is now de-energized. Since in the high speed stage, a part of the current flow causes a braking torque and in addition increases the resistance of the current path, a tilt of the characteristic of the electric motor and a reduction of the starting torque is effected. As a result, an increase in the rotational speed is achieved with a corresponding position of the operating point on the torque characteristic curve. By suitable choice of the angle between the first brush 1 and the third brush 3 the desired characteristic spread can be set. The larger the angle between the first brush 1 and the third brush 3 is, the stronger the characteristic spread is.

• – der Magnetfluss teilt sich in mehrere Teilpfade auf, wodurch die Jochdicke reduziert werden kann,
• – das Ankerquerfeld, das zur Entmagnetisierung der Magnete führt, teilt sich ebenfalls auf mehrere Teilpfade auf, wodurch die Magnetdicke reduziert werden kann, ohne dass eine Entmagnetisierung auftritt, und
• – die Ankerwicklung weist bei höherer Polzahl einen geringeren Wickelschritt auf, was zu einer Verkleinerung der Wickelköpfe und somit zur Einsparung von Kupfer und einer Reduktion der Ankerlänge führt.

Next is known in electric motors, the use of 4- and multi-pole motors with only one speed level. By increasing the number of poles active motor mass can be saved because

• - The magnetic flux is divided into several sub-paths, whereby the yoke thickness can be reduced,
• - The armature transverse field, which leads to the demagnetization of the magnets, is also divided into several sub-paths, whereby the magnetic thickness can be reduced without a demagnetization occurs, and
• - The armature winding has at higher number of poles on a smaller winding step, which leads to a reduction of the winding heads and thus to the saving of copper and a reduction of the anchor length.

at The design of a 4- and multi-pole motor must first at Using a loop winding, the number of brushes corresponding to the increase in Polzahl be adjusted, i. in the transition from two to four magnetic poles must be the number of brushes also increase from two to four. Alternatively, you can however, the commutator bars that contact in an anchor position to the brushes same polarity have to be electrically connected by so-called balancing conductor. This can, with sufficient current carrying capacity of the brush, the Engine continues with only two brushes operate. However, such 4 and multipole motors have only one speed level, i. they need an external speed setting, e.g. by controlling the voltage or by using series resistors to realize different speed levels.

Advantages of the invention

The electric motor according to the invention with the features of claim 1 has the advantage that the advantages of the high pole, namely the lower material consumption and space requirements, combined with the favorable method of speed setting by using a third brush. This is achieved according to the invention in that, in the case of an electric motor with a number n of poles, where n is even and greater than 2, and a number m of brushes with 2 ≦ m ≦ n, a number r of additional brushes for speed setting is 1 ≤ r ≤ n / 2, is provided. In other words, an additional brush is provided according to the invention per pole pair having a pair of brushes. If the electric motor is constructed in such a way that, for example through the use of equalizing conductors, not every pole pair has a pair of brushes, the number of additional brushes can also be correspondingly reduced. Furthermore, even with the use of equalizing conductors, a higher number of brushes up to the full number n + n / 2 of brushes is possible, whereby a redundancy is given. In summary, the electric motor according to the invention has a number of additional brushes in at least four poles, which corresponds at least to the intended brush pairs for driving the motor in only one speed step without the use of equalizing conductors or corresponding internal interconnections. Through these additional brushes) then a second speed level is reached. According to the invention, the use of equalizing conductors between the corresponding commutator bars is preferred because then a minimum number of brushes, ie in particular only three brushes, is required and a brush holder with six or more brushes, which is difficult to implement, especially in small motor diameters, not needs to be provided. As an alternative to equalizing conductors, which are normally applied extra to the winding, it is also possible to provide internal connections of the corresponding commutator bars, the Ver circuit is then provided directly in the commutator.

The under claims show preferred developments of the invention.

at the electric motor according to the invention preferably n = 4, i. it is a 4-pole motor, at a number m of two brushes and a number r of an additional one Brush, i.e. with equalization conductors or internal interconnections between corresponding commutator blades.

Further Preferably, the electric motor according to the invention comprises fourteen uniformly distributed commutator bars, from each opposite Commutator blades through a respective compensation conductor or an internal interconnection are connected.

at the electric motor according to the invention are preferably a first brush and a second brush over the the electric motor operated at a first speed level becomes mechanical at an angle of 90 ° arranged to each other, and a third brush over which the electric motor together with the second brush operating at a second speed level is either in a position between the first and the second brush or arranged in a position offset by 180 ° to this position. It is also possible according to the invention that the first brush and / or the second brush around 180 ° to the specified position are arranged offset.

Of the electric motor according to the invention is not on a number of four poles at a number of three to brush limited. Likewise more or less than fourteen evenly distributed commutator bars can be provided and the offset of the brushes to each other can also be different and hang from the chosen one Motor design from. in principle is a 4- and multipolar motor having at least one pair of brushes, with a additional brush for each provided brush pair Mistake. The extra brush will either in a position between the brushes of the brush pair or in one too this position offset by a certain angle position arranged. This particular angle is determined by the arrangement of equalizing conductors or internal interconnections. In the case that opposite Commutator blades through a respective compensation conductor or a respective internal interconnection are connected, it is 180 °. By doing Case, each three evenly over the circumference Distributed commutator blades with a balancing conductor or a internal interconnection, it is 120 ° or 240 °. In other words, one becomes respective third brush, if it is not located in the position between the brushes of the brush pair, arranged in such a position, where the same commutator bars be energized as if the third brush in the position between the brushes pair arranged would. The to brush of the brush pair can also be arranged offset accordingly. As previously discussed, can also in the case of equalizing conductors or internal interconnections for redundancy, a higher one Number of brushes be provided as three. These are then each in one of or several of the positions in which the respective third brush could be moved.

drawing

following becomes a preferred embodiment of the invention with reference to the accompanying drawings. In the drawing is:

1 a brush arrangement according to a first preferred embodiment of a four-pole motor according to the invention with three brushes, in which opposite commutator bars are connected to equalizing conductors,

2 a second preferred embodiment of a brush assembly of a four-pole motor according to the invention with three brushes, are connected to the opposite commutator bars with equalizing conductors, and

3 a brush positioning of a 2-pole motor with three brushes according to the prior art

Embodiments of the invention

Hereinafter, referring to 1 and 2 two preferred embodiments of an electric motor according to the invention described by way of example.

The preferred embodiments are 4-pole wiper motors with equalizing conductors. The stator has fourteen slots each, correspondingly, the commutator has fourteen commutator bars 5a of which each of the opposed commutator bars are connected by a balancing conductor (not shown). The first brush 1 to which the positive operating voltage is applied in the first speed stage, and the second brush 2 , which serves as a ground brush for both speed levels, are arranged at an angle of 90 ° mechanically to each other. This corresponds to a pole pair number p = 2 electrically 180 °. The four stator poles are schematically represented by four alternating polarized magnetic poles 4a - 4d shown.

In the first in 1 In the embodiment shown, the third brush, to which the positive operating voltage is applied in the second speed stage, is at an angle of 35 ° to the first brush 1 staggered between the first brush 1 and the second brush 2 arranged. By using the Auslgeichsleiter between opposite commutator, the third brush 3 According to the invention also be arranged offset by 180 ° mechanically offset to this position. This is the second in 2 shown embodiment, in which the third brush 3 225 ° from the first brush 1 is arranged offset, the angle of 225 ° here opposite to the direction of rotation of the rotor 5 is measured, as well as the offset of 90 ° of the second brush 2 to the first brush 1 and the offset of 35 ° between the first brush 1 and the third brush 3 in the first embodiment.

Claims (4)

Electric motor, with a number n of poles ( 4a - 4d ), where n is even and greater than 2, and a number m of brushes ( 1 . 2 ), with 2 ≤ m ≤ n, characterized by a number r of additional brushes ( 3 ) for speed setting, with 1 ≤ r ≤ n / 2. Electric motor according to claim 1, characterized in that n = 4 for a number m of two brushes ( 1 . 2 ) and a number r of an additional brush ( 3 ). Electric motor according to claim 2, characterized by fourteen uniformly distributed commutator bars ( 5a ), of which in each case opposite commutator bars ( 5a ) are connected by a respective balancing conductor or by an internal interconnection. Electric motor according to claim 2 or 3, characterized in that a first brush ( 1 ) and a second brush ( 2 ), via which the electric motor is operated in a first speed stage, are arranged at an angle of 90 ° mechanically to each other, and a third brush ( 3 ), via which the electric motor together with the second brush ( 2 ) is operated at a second speed level, either in a position between the first brush ( 1 ) and the second brush ( 2 ) or in a position offset from this position by 180 °.