DE102006039594A1 - DC machine - Google Patents

Abstract

In a DC machine (1) with a number of carbon brushes (12), each slidably disposed in a longitudinal direction in a coal guide (14), the brush fire is reduced or avoided and thus excessive noise and high-frequency interference are largely excluded. For this purpose, according to the invention, a carbon guide (14) is provided, which is formed by a base surface (20), optionally by side surfaces, and by a number of guide surfaces (16) bevelled relative to the base surface (20).

Description

The The invention relates to a DC machine with a number of carbon brushes, the each in their longitudinal direction slidable in a guide channel, the so-called coal guide, are arranged.

The for the operability of electrical machines, for example of direct current machines, required provision of a relative to the winding rotating or migratory electricity based on a direct current as Input current is usually over the so-called commutator, also referred to as Stromwender achieved. Usually Stromwendeeinrichtungen are designed as a lamella brush system, for example in DC machines. A DC machine can be executed as an electric motor, which is operated with direct current, or as a generator, the converts mechanical energy into direct current. In some applications, can a DC machine also fulfill both functions.

A DC machine typically includes as essential components an immovable outer part, the stator, and a rotatably mounted inner part, the rotor or anchor. In conventional DC machines includes the immovable part at least one electromagnet or in smaller, less powerful designs at least one permanent magnet.

basics Advantages of the typical DC machine, for example, in comparison with induction machines, is the changeable one Operating speed, with the same torque over the voltage amplitude can be controlled. Through this construction, DC machines can be used in a big one Speed range can be used.

In Electric motors with commutators are used for tapping the generated Electricity, used in electric generators for feeding the electricity, carbon brushes. Earlier instead of graphite, brush brushes were used as sliding contact, therefore the term brush. Such a carbon brush consists mostly of graphite and poses via slip rings or collectors a (sliding) contact with the rotating part of the machine, the rotor or anchor, forth. Because of the sometimes high speeds, it can be conventional DC machines in the short moments when the brush of the Commutator is electrically isolated or two differently charged Short slats, come to electrostatic discharges, which are visible as sparks become. This is the so-called brush fire.

This so-called brush fire may be the cause of high-frequency interference be, for example, the DC machine in operation radiates and feeds back into the pipeline network and thus disruptions for others Consumers in the network can cause. Also, the rotational speed limited by this sparking, as the carbon brush at high speeds gets hot and faster than in This DC machines wears typical temperature ranges. Of Furthermore, high speeds cause a higher induction voltage, the a revolving brush fire can initialize.

One Another disadvantage of the typical use of carbon brushes is the occurring noise, the by the shock excitations the coal guide, caused by the tangential and radial excitation of the carbon brushes the commutator, arises. Responsible for this stimulation of carbon brushes is the game of carbon brush in the coal leadership. However, this game is necessary to the carbon brush the radial contact with the commutator to allow, especially in heat this game is a change the different extent of different materials that in the carbon brush and in the coal leadership Find use finds out.

Of the Invention is therefore the object of a DC machine specify the above-mentioned type in which reduces the brush fire or avoided is and therefore an excessive noise as well as high-frequency interference are largely excluded.

These The object is achieved according to the invention by the coal leadership from a base surface, if necessary of side surfaces and formed by a number of guide surfaces chamfered relative to the base surface is.

advantageous Embodiments of the invention are the subject of the dependent claims.

The Invention goes from consideration from that, the so-called brush fire essentially by the play between the carbon brush and the coal leadership is conditional. Therefore, this should be minimized. In spite of the different expansion behavior of said components the system under the influence of temperature the free mobility of the carbon brush appropriate guidance should be provided. To is the coal leadership suitably designed.

Usually, the coal guide is designed as a rectangular shaft. The intended and necessary game of carbon brush in the tangential direction in the coal guide is over the entire Height of the carbon brush and carbon guide available and allows for excitation of the carbon brush and thus the noise and sparking, the so-called brush fire. A chamfer of the guide surfaces and the pressure of the carbon brush in the direction of the base surface and the relative to the base beveled guide surfaces achieved at least a selective contact and leadership of the usual way rectangular shaped carbon brush in the coal guide.

Around the contact between the carbon brush and the coal leadership form as surface contact, points the carbon brush also a guide surface, the to the guide surface of the carbon guide is adjusted.

Around the trained bevel both the guide surfaces of the carbon brush as well as the guide surfaces of the carbon guide for one as possible backlash-free guide the carbon brush in the coal leadership Provide, advantageously acts a pressing force on the carbon brush in Direction of the base area.

Of the Pressure of the carbon brush in the direction of the base area the coal leadership preferably takes place via the integration of an additional Component such as a spiral, torsion or spiral spring in the coal guide. The Spring element can also manufacturing technology in the coal guide or be provided in one of the attachments. In a particularly advantageous Design, the pressure of the carbon brush by a radial Directional spring preload via a lever deflection.

The particular advantages of the invention are that by the bevel the guide surfaces both the carbon brush as also the coal leadership when pressed the carbon brush an adjustment and a lateral fixation takes place, the sparking or the impact stimuli resulting from lateral oscillation eliminated. This will both the noise of the DC machine minimized as well as the EMC behavior by reducing the high-frequency disorders improved.

Farther lie benefits of this design in a simpler and therefore more cost-effective production of the lamella brush system, as on the carbon brush itself and on the Koh leführung greater manufacturing tolerances are acceptable than in the usual implementation.

Of Furthermore, the tool life compared to the previous versions higher, because the wear of the carbon brush by minimizing shock excitation and the sparking is reduced, resulting in the operation of the DC machine also inexpensive effect.

One embodiment The invention will be explained in more detail with reference to a drawing. Show:

1 a DC machine in cross-section,

2 the DC machine after 1 in perspective view,

3 a coal guide the DC machine after 1 on average, and

4 a carbon brush of the DC machine behind 1 in three-dimensional view.

Same Parts are provided in all figures with the same reference numerals.

The DC machine 1 according to 1 is basically constructed in the usual way, with a field winding 2 in a stand 4 , Also called stator, is arranged. The excitation winding 2 generated during operation of the DC machine 1 a not shown here temporally and spatially constant field. This type of execution is also referred to as Außenpolmaschine. An anchor 6 , also referred to as rotor or rotor, carries a winding or armature winding 8th , in the case of movement of the anchor 6 a voltage is induced.

2 also shows a DC machine 1 as well as the interaction of the components. The armature winding 8th of the anchor 6 is over a commutator 10 connected. The contacts 12 of the commutator 10 Also referred to as coal or brush or carbon brush, are constructed such that they during the rotation of the armature 6 constantly the polarity of the armature winding, not shown here 8th switch. The carbon brush 12 consists of a highly electrically conductive material, such as graphite, which is also characterized by the property that during operation by the pressing of the carbon brush 12 to the commutator 10 Abrasion occurs, which is the contact surface between carbon brush 12 and commutator 10 lubricates. By the concern of the carbon brush 12 at the commutator 10 and the resulting change of polarity is in a DC machine 1 ensures the rotational movement. Is the DC machine 1 not designed as an electric motor, but as a generator, created by the function of the commutator 10 from the alternating current of the armature 6 DC.

The leadership of the carbon brush 12 a commutator 10 takes place in a so-called coal shaft 14 , also referred to as coal guide, ge Mäss 3 , When operating the DC machine 1 and by the concern of the carbon brush 12 at the commutator 10 heat is generated, which increases with increasing speed. Because the coal leadership 14 and the carbon brush 12 Made of different materials, these stretch when heated in the operation of the DC machine 1 different. This is a game between the inner wall of the coal guide 14 and the carbon brush 12 provided that covers the different dimensions. Through an air gap created by the game is the carbon brush 12 in the coal leadership 14 tangentially and radially movable and generated by the inevitable tangential and radial movement and the impact of the carbon brush 12 on the inner wall of the coal guide 14 a sound. This noise increases as the speed of the DC machine increases 1 ,

Around the air gap between the carbon brush 12 and the inner wall of the coal guide 14 and thus the movement of the carbon brush 12 in the tangential direction at the commutator 10 to avoid assigned side, but still enough to ensure the different expansion behavior of the components are the guide surfaces 16 the coal leadership 14 , like from the 3 visible, bevelled.

To significantly enhance the guiding effect of the carbon brush 12 in the coal track provided with a bevel to the base surface 14 to reach is the guiding surface 18 the carbon brush 12 with one of the guide surface 16 the coal leadership 14 adapted bevel designed.

By the bevel of the guide surface 16 in the coal leadership 14 relative to the base area 20 is the guide of the carbon brush 12 guaranteed at least in the contact area. For this purpose, advantageously a contact pressure of the carbon brush 12 in the direction of the base area 20 to the commutator 10 , so that the carbon brush 12 in the chamfered part of the guide surface 16 the coal leadership 14 remains. The contact pressure acts axially on the carbon brush 12 , Wherein a device for generating the contact pressure in the coal guide 14 is integrated, which is usually designed as not shown here, spiral, torsion or bending spring.

A particularly advantageous design of the device for generating the contact pressure shows the 4 , A feather 22 creates by its bias a pressure on a lever 24 , the side to the carbon brush 12 in the coal channel 14 is integrated. By a lever deflection via a lever 24 whose axis 26 runs in the tangential direction, creates an axial contact pressure on the carbon brush 12 in the direction of the base area 20 the coal leadership 14 ,

By the bevel of the guide surface 18 the carbon brush 12 as well as the chamfer of the guide surface 16 the coal leadership 14 in conjunction with the axial contact pressure on the carbon brush 12 in the direction of the base area 20 the coal leadership 14 is exercised arises between the guide surface 16 the coal leadership 14 and the guide surface 18 the carbon brush 12 a line contact or a surface contact.

The design of the contact between the coal guide 14 and the carbon brush 12 As surface contact largely reduces the noise, as caused by shock excitation between the carbon guide 14 and the carbon brush 12 , as well as the so-called brush fire, which at the contact surface between carbon guidance 14 and the carbon brush 12 can arise.

By generating the contact pressure of the carbon brush 12 to the commutator 10 in the direction of the base area 20 the coal leadership 14 via a deflection system according to 4 and a suitable design of the spring 22 can be largely ensured that the contact pressure in each state region of the carbon brush 12 , which is dependent on the temperature and degree of wear, is the same. This results in a uniform running behavior of the DC machine 1 reached. Also a damping of the movement of the carbon brush 12 in the coal leadership 14 through the over the lever 24 and the spring 22 generated contact pressure can be achieved.

1

DC machine

2

excitation winding

4

stand

6

anchor

8th

armature winding

10

commutator

12

carbon brush

14

carbon guide

16

Guide surface of carbon guide

18

Guide surface of carbon brush

20

footprint

22

feather

24

lever

26

axis of the lever

Claims (3)

DC machine ( 1 ) with a number of carbon brushes ( 12 ), each in its longitudinal direction displaceable in a guide channel ( 14 ) arranged from a base surface ( 20 ), optionally of side surfaces and of a number relative to the base surface ( 20 ) beveled guide surfaces ( 16 ) is formed. DC machine ( 1 ) according to claim 1, whose carbon brushes ( 12 ) in their contouring on the guide surfaces ( 16 ) adapted beveled contact surfaces ( 18 ) exhibit. DC machine ( 1 ) according to claim 1 or 2, whose coal guide ( 14 ) one to the base area ( 20 ) directed to the carbon brush ( 12 ) has acting pressure device.