EP1133815B1 - Commutation device, especially a commutator, and method for producing such a device - Google Patents

Abstract

A commutator comprises a pre-formed, cylindrical carrier (3) with a rotational axis (2), and electrically conducting commutator segments (4). The segments are fixed to the carrier using a connecting agent.

Description

The present invention relates to a device for turning current, in particular a commutator. Such devices are used in particular in electric motors and power generators, for example for power tools, actuators or fuel pumps.

Devices of the generic type are for example from the DE 41 37 400 C2 known. In this case, a segment composite is punched out of a rolled or drawn copper strip and then rolled, split or plowed and injected with a molding compound, which forms the supporting body of the commutator in the hardened state. Subsequently, the bore of the support body must be processed and the hooks of the commutator segments are bent for attachment of the coil ends. After another peeling or overwinding the commutators are electrically tested and then mounted by means of a press fit on the motor shaft.

Furthermore, from the DE 195 30 051 A1 a plug-in commutator known in which the individual commutator segments are inserted into a mounting basket and then with the formation of the support body with a Preßmasse be ejected. This is followed by further processing and test steps to meet the requirements for the accuracy of the geometric dimensions of the commutator and its stability.

From the DE-OS-2 352 155 a commutator for a miniature electric motor and a method for its production is known in which a desired number of Kommutatorblechen be mounted on a lateral surface of a core at certain angular ranges by means of an adhesive.

The WO 95/14319 shows a commutator and a method for its preparation, in which the segment recordings have an undersize and the insulator and / or the segments have an elasticity such that the inserted into the segment recording segments are defined both by positive engagement and by frictional connection. The segments can also be caulked or glued to the support body.

The US 3,819,967 shows a drum commutator in which the Kommutatorsegmente are fixed by gluing to the cylindrical support body.

The EP 0 361 860 A2 shows a commutator, according to the preamble of claim 1, wherein the segments are fixed with the interposition of an adhesive layer on the support body. In addition, the segments are in any case bent at one end hook-shaped so that they are hooked into a radially recessed from the peripheral surface and extending axially incision in the support body.

The EP 0 127 801 A1 shows a commutator for an electrical machine with a sintered ceramic body, such as aluminum oxide.

The metallic segments are oxidized on the inner narrow side of the surface and then connected to the ceramic body by heating to the temperature required for the production of a eutectic.

The US 5,629,576 shows a plan commutator with carbonaceous Kommutatorsegmenten, which are defined by means of an adhesive binder to a connecting means made of copper. The alignment of segment to connecting means takes place via a recess in the carbon-containing segment, in which the connecting means is introduced.

In the known commutators a variety of manufacturing and testing steps is required in order to ensure the required accuracy and reliability.

The invention is therefore based on the problem to provide a commutator, which has a high accuracy in terms of its geometric dimensions and high long-term stability and is easy to produce.

The problem is solved by the device defined in claim 1. Particular embodiments of the invention are disclosed in the subclaims.

In addition to the positioning according to the invention, the segments may be fixed to the support body by means of a connecting means arranged essentially between the support body and the segments. The support body is usually made of an electrically insulating material, in particular of a plastic such as a thermoset, a thermoplastic or a ceramic. Alternatively, a metallic carrier body is also suitable, for example aluminum, whose surface is preferably provided with an electrically insulating coating, for example a lacquer coating or a metal oxide layer, which can also be produced by oxidation of the metallic carrier body. The support body can also be constructed in two or more layers, in particular having an elastic inner hub which is surrounded by a temperature-stable outer shell, on which the segments can be fixed. The elastic inner shell provides the required interference fit for mounting the commutator on the motor axis. The commutator segments are usually made of copper or a copper compound, alternatively, other materials in accordance with the requirements placed in terms of conductivity, temperature stability and chemical resistance into consideration. The connecting means is preferably arranged in layers between the segments and the support body and can be applied, for example, before setting on the support body and / or on the segments.

The support body and the segments have cooperating means for positioning and aligning the segments with respect to the support body. These can be realized by point, line or sheet-shaped projections and corresponding recesses on the support body or on the segments. For example, the segments may have web-shaped projections which can be inserted into corresponding grooves aligned parallel to the axis of rotation on the peripheral surface of the support body. In the case of a flat commutator, webs aligned in the radial direction on an end face can engage in corresponding recesses or grooves on the associated segment, or the cylindrical support body can have an axially projecting, preferably circumferentially annular, overhang on its end face at the edge, which has a centering on the end face segment disc to be defined guaranteed, which is then divisible into individual, mutually electrically insulated commutator segments.

As far as the bonding agent is an adhesive layer, it may be filled according to the electrical and / or thermal requirements with appropriate additives. By a ceramic filler, for example, the thermal expansion coefficient of the adhesive layer can be reduced. By an electrically conductive, in particular metallic filler, for example on Ag, Cu or Ni-based, if necessary, an electrically conductive connection between the segment and the support body can be produced, for example, if in a Plankommutator the support body comprises electrically conductive, segment-shaped connecting tracks , The fillers may in particular define a distance between the commutator segments and the carrier body and thus the thickness of the adhesive layer, preferably by spherical fillers, in particular glass or ceramic balls. The layer thickness is for example between 20 and 250 microns, preferably between 50 and 100 microns. The layer thickness can also be predetermined by preferably integrally formed by the support body or the commutator segments spacers, for example, by corresponding point, line or sheet-shaped projections. The adhesive is in particular to be selected or treated so that it absorbs as little moisture after curing, especially with copper forms a permanently solid compound and is dimensionally stable even under mechanical and / or thermal stress.

As far as the connecting means is a solder or welding layer, the commutator has a particularly high temperature stability and chemical resistance. In this case, preference is given to low-melting soft, hard or glass solders, for example low-melting lead / tin solders or glass solders having a high proportion of lead oxide. By Ultrasonic or friction welding achieves a particularly low connection temperature.

As far as the segments and the support body non-positively cooperating anchor and receiving means, the segments can be inserted into the support body and the spring against each other acting anchor and receiving means a sufficiently stable clamping connection is ensured. In addition, the segments can still be fixed to the support body by the connecting means. However, it is also possible to dispense with an additional connecting means and to define the segments exclusively with the clamping connection forming anchoring and receiving means. Both the segments and the support body may have only anchor means or only receiving means or a combination of anchoring and receiving means. It is only essential that an anchor or receiving means of the segment cooperates with a receiving or anchoring means of the support body.

It is particularly advantageous if the segments can be inserted or clipped into the support body in the radial direction, for example in the case of a drum commutator, or, for example, can be inserted axially into an end face of the support body in the case of a planar commutator.

Furthermore, it is advantageous if at the same time positioning and alignment of the segments takes place when inserting the segments into the carrier body by means of the armature or receiving means. Preferably, the means for positioning and aligning extend parallel to the axis of rotation along a peripheral surface or radially to the axis of rotation along an end face of the support body. For the means for positioning and aligning all suitable shape designs come into consideration, in particular webs with triangular, quadrangular, semi-circular or dovetailed cross section. For anchoring are suitable in particular cross-sectional shapes, which undergo a widening in the depth and in particular are provided with a tip for easy insertion.

In an associated manufacturing method, the segments are fixed to the support body by means of a connecting means arranged substantially between the support body and the segments. For example, the support body can be brought as a whole before setting the segments in a connecting agent immersion bath. Alternatively or additionally, the segments can also be provided with the connecting means at least on their surface facing the carrier body. Optionally, the surfaces of the support body and / or the segments to be cleaned and / or provided with a bonding agent prior to attachment of the bonding agent. The conditioning of the surfaces may preferably be carried out in a vacuum process, for example in an ionic or plasma vacuum process. Due to the surface treatment, a sufficient aging and corrosion resistance of the bonding layer against the stresses during later use and / or a uniform wetting with the bonding agent can furthermore be achieved. In particular, in a bonding and aftertreatment of the adhesive joint is advantageous in order to avoid corrosion and / or infiltration and thus a reduction in the strength of the compound.

There are provided means for positioning and aligning the segments whose shape is designed so that when feeding the segments automatically positioning and alignment takes place, for example, by triangular in cross-section grooves in the support body, are inserted into the corresponding cross-sectionally triangular webs of the segments. In this case, the connecting means can be inserted, for example, before being fed as an adhesive strand into the groove. In the subsequent Feeding the segments, the connecting means is displaced and forms a flat connecting layer between the support body and segment.

As far as fixing a clamp connection between anchor and receiving means, the arranged between the support body and the segments connecting means can be omitted. In this case, the setting is carried out only by the incoming clamping connection anchor and receiving means.

As far as a connecting means is provided, this is in particular a gluing, soldering or welding layer into consideration. The maximum temperature during further processing can be up to 300 ° C for a short time. The curing of an adhesive layer should always be carried out at the lowest possible temperature, for example in the temperature range between 50 and 250 ° C, preferably between 170 and 200 ° C.

As far as the segments are successively supplied to the support body, this can be done by stepwise rotation of the support body about its axis of rotation and piecemeal application of the segments or by rolling the support body on the present example in a strip composite segments. When piecewise supplying the connection between the support body and the respective segment can be done either immediately following the feeding or finally for all supplied segments together, for example by enclosing the equipped with segments support body with a pressing and / or heating tongs.

As far as all segments are supplied to the support body at the same time, this can be done with a suitable pressing and / or heating tool, which subsequently to the feeding for the mechanically safe Setting the segments on the support body ensures. It can be done for example by pressing the segments into the support body, in particular by telescoping the anchor and receiving means, and / or by heating the segments to melt the bonding agent and producing a bonding layer.

Fig. 1

zeigt eine Seitenansicht eines aufgeschnittenen Kommutators,

Fig. 2

zeigt entsprechend dem Schnitt II-II der Fig. 1 verschiedene Ausführungsarten der Positionierungsmittel,

Fig. 3

zeigt ein ausgestanztes ebenes Kommutator-Segment,

Fig. 4

zeigt eine mögliche Montageart des Segments der Fig. 3, und

Fig. 5

zeigt das Herstellverfahren in Form eines Flußdiagramms.

Further advantages, features and details of the invention will become apparent from the dependent claims and the following description in which several embodiments are described in detail with reference to the drawings. The features mentioned in the claims and in the description may each be essential to the invention individually or in any desired combination.

Fig. 1

shows a side view of a cut-open commutator,

Fig. 2

shows according to the section II-II of Fig. 1 various embodiments of the positioning means,

Fig. 3

shows a punched flat commutator segment,

Fig. 4

shows a possible way of mounting the segment of the Fig. 3 , and

Fig. 5

shows the manufacturing process in the form of a flow chart.

The Fig. 1 shows a side view of a cut commutator 1. The substantially cylindrical and a rotation axis 2 having support body 3 is preferably made of a thermoset or thermosetting plastic, for example, made of a hollow cylinder made of injection-molded phenolic resin. At the cylindrical outer wall are electrically isolated from each other in the circumferential direction and preferably copper or a copper compound containing segments 4 defined, one end of which is bent in a hook shape for the connection of the associated (not shown) coil winding. The segments 4 are fixed by means of a connecting layer 5 arranged substantially between them and the support body 3, in the present case by means of a Adhesive layer of epoxy resin, polyurethane resin or phenolic resin adhesive layer. In the lower half of the Fig. 1 is a second segment 4 'is shown, which integrally has two aligned in the radial direction anchor means 4 ", which not only increase the strength of the attachment of the second segment 4' on the support body 3, but at the same time serve for positioning and alignment of the second segment 4 '. The anchoring means 4 "engage in corresponding receptacles in the support body 3, which may be formed, for example, by circumferential annular grooves 3 'or circumferential annular shoulders 3." A cone 15 is formed on the support body 3 in order to push the support body 3 onto a support body (not shown) ) To simplify motor axis.

The Fig. 2 shows according to the section II-II of Fig. 1 various embodiments of the means for positioning, aligning and anchoring the segments 4 on the support body 3, in addition to the in Fig. 4 Positioning means 309, 311 according to the invention can be provided. In the partial image 2A, the segment 4a has two parallel to the axis of rotation 2 (perpendicular to the plane) extending, triangular in cross section webs 4a ', which are pressed either under force and / or temperature effect in the support body 3 or in correspondingly shaped grooves in the Support body 3 are inserted. The partial image 2B shows a segment 4b with a single centric, in section also triangular and parallel to the axis of rotation 2 extending web 4b '. The partial image 2C shows a segment 4c with an anchor means 4c ', which initially extends in the form of a ridge in section and has an approximately circular thickening at its end directed towards the rotation axis 2. The anchor means 4c 'may extend parallel to the rotation axis 2 web-shaped over a part or over the entire axial length of the support body 3 or it may be punctiform, for example in the form of a mushroom. In any case, the anchor means 4c 'engages behind a corresponding recess in the support body 3, which deforms elastically in this area and a clamping force for securely fixing the segment 4c applies. The partial image 2D with the segment 4d and the anchor means 4d 'as well as the partial image 2E with the segment 4e and the cross-sectionally dovetail-shaped anchor means 4e' show two further of almost any possible embodiments of the anchor means. The preferably integrally formed with the segment 4f anchor means 4f 'of the partial image 2F is formed in coordination of geometry and material so that it initially deformed when pressing the segment 4f in the support body 3 and the full impressions a substantially T-shaped recess of the Support body 3 engages behind. Also in this embodiment, there is an elastic deformation of the support body 3 in the under-reach area, which applies the required clamping force for the segment 4f. The partial image 2G shows a bent on its longitudinal sides in the radial direction or correspondingly shaped segment 4g, wherein the two legs 4g 'either engage in corresponding recesses in the support body 3 or cut into it under force. The partial image 2H shows a segment 4h with an annular segment-shaped cross section, which is inserted into a corresponding recess of the support body 3. The sub-images 2A to 2H show only a selection of the variety of possible positioning, alignment and anchoring options for the segments 4 on the support body 3. Of course, the anchor means on the support body 3 and corresponding recesses or receiving means formed on the segments 4 in an analogous manner be. In addition or as an alternative to the anchoring means 4c 'to 4f', the fixing may also be effected by a connecting layer 5, for example an adhesive, solder or welding layer.

The Fig. 3 shows a punched flat segment 304 made of copper for a drum commutator according to the invention, which consists essentially of the actual rectangular segment surface 308 is made, one of whose narrow side two outer positioning means 309 and a central web 310 protrude, the latter being provided for the connection of the coil winding. On the opposite narrow side, a positioning means 311 is also formed.
The positioning means 309, 311 have at their ends in each case at right angles projecting lugs. After the segment 304 has been provided with a curvature adapted to the support body, the positioning means 309, 311 are bent by approximately 90 ° with respect to the segment surface 308 in the direction of the arrow 312, as in FIG Fig. 4 shown. The bent positioning means 309, 311 engage in corresponding receiving means of the support body 303 and are thereby positioned and aligned. The determination of the segment 304 on the support body 303 can be effected exclusively due to a clamping between the positioning means 309, 311 and the support body 303 or additionally by a connection layer 305. The support body 303 is for this purpose preferably made of an elastic core 314, which provides the elastic deformation for the clamping effect on the segments 304 and the positioning means 309, 311 and for the press fit on the motor axis (not shown). With respect to the axis of rotation 302 radially outward, the support body 304 has a shape-and temperature-resistant outer shell 315. In the right half of the picture Fig. 4 an alternative possibility of bending of the positioning means 309 is shown, in which the bent positioning means 309 are no longer flat, but by turning again a hook 309 'is formed, which engages in a corresponding recess in the core 314. In a corresponding manner (not shown), the opposing positioning means 311 can also be hooked.

The Fig. 5 shows a flowchart representing the manufacturing process. The molding of the support body 3 and the associated segments 4 takes place in parallel, preferably both the support body 3 and the segments 4 are cleaned prior to feeding by appropriate solvents or cleaning agents and, if necessary, applied a bonding agent. The feeding of the segments 4 to the support body 3 can be done successively or simultaneously, in each case in the feeding takes place an alignment and positioning of the segments 4 with respect to the support body 3. Finally, the segments 3 by clamping, gluing, soldering or welding set the support body 4. Gluing, soldering or welding can be provided as an alternative or in addition to clamping.

Claims (6)

1. Commutation device, in particular commutator (1) with a preformed, substantially cylindrical carrier body (3; 302) having a rotation axis (2; 302) and with electrically conductive commutator segments (4; 304) established on the carrier body (3; 303), where the carrier body (3; 303) and the segment (4; 304) have co-operating means for positioning and alignment of the segments (4; 304) in relation to the carrier body (3; 303) and where the segments (4; 304) lie with their segment face (308) on a generated surface of the carrier body (3; 303) and opposing end sections as positioning means (309; 311) are bent away in relation to the segment face (308), characterised in that the two positioning means (309, 311) in the bent state are flat and that the bent flat positioning means (309, 311) engage in corresponding receiver means on the two side faces of the carrier body (303) and are thereby positioned and aligned.
2. Device according to claim 1, characterised in that the two positioning means (309, 311) at their end remote from the segment face (308) have lugs protruding at right angles, which in the bent state extend in the plane of the face of the carrier body (303).
3. Device according to claim 1 or 2, characterised in that the segments (304) are also established on the carrier body (303) by a connecting layer (305) arranged substantially between the carrier body (303) and the segments (304).
4. Device according to claim 3, characterised in that the connecting layer (305) is an adhesive layer, preferably an epoxy resin, polyurethane resin or phenol resin adhesive layer.
5. Device according to claim 3, characterised in that the connecting layer (305) is a solder or weld layer, in particular a soft, hard or glass solder layer or an ultrasound, friction or electrode weld layer.
6. Device according to any of claims 1 to 5, characterised in that a web (301) bent away from the segment (304) at the end is provided for connection of the coil winding.

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