EP1186077A1

EP1186077A1 - Method for producing a flat commutator and a commutator produced according to this method

Info

Publication number: EP1186077A1
Application number: EP00945730A
Authority: EP
Inventors: Eckhard KÖNIG
Original assignee: Kirkwood Industries GmbH
Current assignee: Kautt and Bux GmbH
Priority date: 1999-06-12
Filing date: 2000-06-09
Publication date: 2002-03-13
Anticipated expiration: 2020-06-09
Also published as: WO2000077889A1; BR0011565A; JP4156834B2; ATE263446T1; DE19926900A1; US6789306B1; JP2003502809A; EP1186077B1; DE50005913D1

Abstract

A method for producing a flat commutator includes forming a metallic supporting body with segment supporting parts and forming a hub of an electrically insulating material. The supporting body is connected in an electrically conductive and mechanically fixed manner to an annular disc resistant in a reaction-promoting environment. The supporting body is divided into segment support parts. The annular disc is divided into annular segments. The surfaces of the metallic segment supporting parts which are bare as a result of the division of the supporting body are coated with a coating that is resistant to the environment. The coating is carried out by currentless deposition. The commutator produced according to this method has the hub adjacent to the supporting body in the vicinity of the division.

Description

Process for producing a flat commutator and commutator produced by this process

The invention relates to a method for producing a flat commutator according to the preamble of claim 1 and a commutator produced by this method. Commutators of this type can be used, in particular, in electric motors for driving a fuel pump which pumps fuels obtained from renewable raw materials.

In the production method known from WO 97/03486, a cup-shaped carrier body, which forms metal and segment-supporting parts, is formed from a copper plate pre-segmented by grooves and injection-molded with a hub formed from an electrically insulating molding compound. The carrier body is then removed on its side forming a contact surface for the carbon-containing ring disk to such an extent that the segment supporting parts are electrically separated from one another by the grooves filled with molding compound. Then the washer is applied and then in accordance with the segmentation of the carrier body in

CONFIRMATION COPY Segments divided, the separating slots protruding into the area of the grooves filled with molding compound.

Since, according to the known method, the carrier body is segmented before the ring disk is applied, it requires the additional method steps of introducing grooves into the carrier body and removing the carrier body into the area of the grooves. In addition, the division must take place exactly in the area of the grooves in order to ensure resistance to the reaction-promoting environment.

DE 36 25 959 C2 shows a drum commutator and a method for its production, in which protective parts by plating with a copper either on a cylinder which is produced by rolling in a base plate consisting of a mother or base metal copper, or on a hollow cylindrical tube piece -Nickel or silver-nickel alloy are applied, at least on the surfaces that come into contact with the brushes. Furthermore, the mother metal of the commutator segments is tin-plated on its surface by electrolytic plating (column 13, lines 16 and 17) to prevent the copper body from being exposed to a fuel such as gasohol so as to prevent the fuel from decomposing. The patent specifies a mixture of unleaded petrol and 10 to 15% ethyl alcohol as gasohol.

DE 44 35 884 C2 shows a commutator for use in

Fuel pumps, with lamellae arranged over the circumference of the commutator, which are in sliding contact with a brush arrangement, made of a wear-resistant copper-magnesium alloy, the magnesium content of the lamellae being between 0.05 and 2.00 mass percent. DE 29 03 029 C2 shows, inter alia, a method for producing a flat commutator, in which a copper plate with a disk-shaped sheet made of silver or a silver alloy which is insensitive to gasoline is applied, then slit at regular intervals and finally the bared copper parts of the commutator lamellae are galvanically applied , electroplated layer of silver or tin.

The invention is therefore based on the problem of a method for

To provide the manufacture of a flat commutator which overcomes the disadvantages of the prior art, in particular is more cost-effective and nevertheless ensures sufficient resistance of the manufactured commutators in an environment requiring a reaction. In addition, the coating, in particular in undercuts and / or any grooves that may be present due to the division of the carrier body, should be sufficiently thick, as uniform as possible and in any case to give a coherent layer. The invention is also intended to be able to use electric motors for driving a pump for fuels obtained from renewable raw materials.

The problem is solved by the method defined in claim 1 and by the commutator and electric motor defined in the independent claims. Particular embodiments of the invention are defined in the subclaims.

The surfaces of the metallic segment bearing parts that are exposed by the division are covered with a coating that is resistant to the reaction-promoting or aggressive environment. The resistance relates in particular to the protection of the carrier body or the segment support parts and the connection to the washer from decomposition and to the electrical conductivity with regard to the contact resistance between the commutator running surface formed by the washer and the associated segment support part or between the latter and the commutator brush and on the adhesion of the coating to the metallic segment supporting part. In addition, the insulation between the segment supporting parts must be guaranteed. The segment support parts preferably consist essentially of copper and have a high electrical conductivity and ductility. The carrier body is produced, for example, from a punched-out copper plate, which is then shaped into a pot and is injected with a molding compound forming the hub. The especially carbon-containing washer is resistant in the reaction-demanding environment, for example in a hydrocarbon-containing liquid. The ring disk and / or the carrier body are preferably divided by grinding, sawing or laser processing.

The fact that the support body is divided into segment support parts after the connection to the annular disk, eliminates the method steps of inserting the grooves and removing the support body.

The manufacturing process is further simplified by dividing the annular disk and the carrier body in one step. Alternatively, it is contemplated that in a first step the support body formed into a pot and provided with the hub is divided into segment support parts by first slots, then the washer is applied and then the washer is divided into ring segments by second slots, the second Slots preferably smaller than the first Are slots and are disposed within the first slots. The surfaces of the segment supporting parts which are exposed by dividing the carrier body can be coated before or after the application of the annular disc. If the coating takes place before the ring disk is applied, the applied layer can simultaneously be used as a connecting layer with the ring disk.

Because the coating is carried out by deposition, the metallic carrier body can be coated with any materials. Both chemical and physical and mixed deposition processes can be used, for example deposition from the gas phase (chemical vapor deposition, CVD), if necessary plasma or laser-assisted, cathode-ray sputtering (sputtering), vapor deposition, etc. Vossen, Kern ( Ed.): Thin film processes I and II, 1 991.

Because deposition takes place from a solution or suspension, a large number of commutator elements can be coated in one step and thus inexpensively and with good coverage and layer quality. The layer material is preferably in ionic solution or suspension and can be deposited electrolytically (galvanically) or without current on the segment supporting parts.

The fact that the separation from the solution or suspension takes place without current, that is to say without the application of an external voltage, results in a good covering of the elements even in inaccessible places, for example in the separating slots formed by the division. The temperature and concentration of the solution or suspension are chosen so that in complete coverage of sufficient thickness is guaranteed as short as possible.

The fact that the coating is carried out selectively only on the surfaces of the segment supporting parts means that the ring disk and in particular the hub are not coated, as a result of which the layer is detached from these points, for example due to lack of adhesion, and the problems associated therewith during later operation of the commutator . The selectivity of the deposition can be adjusted by appropriate selection of the process parameters during deposition, for example deposition temperature, concentration of the solution or suspension, deposition time, etc., depending on the material to be deposited and / or the carrier body to be coated.

The fact that the coating is carried out with tin, silver or chrome ensures good coverage and adhesion, as well as sufficient resistance, in particular to fuels obtained from renewable raw materials, even with inexpensive materials. Tin in particular offers good contact properties, which is also advantageous for connecting the winding ends to the segment supporting parts.

The fact that the layer thickness is between 0.1 and 10 μm, in particular between 1 and 3 μm, ensures reliable covering and good adhesion and sufficient resistance. These layer thicknesses occur in particular in the case of electroless deposition from a solution or suspension after relatively short deposition times and ensure pore-free covering of the carrier body. Characterized in that in a commutator produced by the method according to the invention, the hub also bears against the carrier body in the region of the division, in particular on the side of the segment support parts facing away from the commutator running surface and / or the surfaces adjoining the surfaces exposed by the division of the carrier body, In this area, too, a secure covering of the metallic carrier body is guaranteed, which reliably prevents the carrier body or the segment carrier parts from being washed away in the reaction-demanding environment.

Characterized in that the hub forms a complete cover of a cylindrical boundary surface of a central bore of the carrier body, the cylindrical inside of the carrier body is also covered with respect to the reaction-requiring atmosphere and the resistance of the commutator is further increased.

The fact that the coating is resistant to a fuel to be pumped means that commutators produced by the method according to the invention can also be used in fuel pumps. Tin, in particular, has proven to be resistant to fuels obtained from renewable raw materials, such as alcohol-based fuels or diesel fuels obtained from rapeseed oil.

Further advantages, features and details of the invention emerge from the subclaims and the following description, in which several exemplary embodiments are described in detail with reference to the drawings. The can in the claims and in the features mentioned in the description may be essential to the invention individually or in any combination.

1 shows a first embodiment of the manufacturing process, FIG. 2 shows a second embodiment of the manufacturing process,

3 shows a top view of a segmented commutator,

4 shows a section IV-IV through the commutator of FIG. 3,

Fig. 5 shows a view of the commutator of Fig. 3 from V-V, and

FIG. 6 shows a view corresponding to FIG. 5 of a commutator produced by the manufacturing method according to FIG. 2.

Fig. 1 shows a first embodiment of the manufacturing process. A copper plate is punched out 50 from a copper sheet, from which a cup-shaped carrier body is then formed 51. The bottom surface of the pot forms the contact surface for the washer to be applied. The bottom surface is not pre-segmented, whereas the cylindrical outer surface of the pot is already segmented by punching out. Likewise, by punching out hook elements are formed for attaching the coil windings and armature elements engaging in the hub. The hub is formed by spraying 52 of the cup-shaped carrier body by means of an electrically insulating molding compound which is temperature-resistant in accordance with the respective requirements. Optionally, the hub and the contact surface of the carrier body can be machined 53, with respect to the hub, in particular, a fine machining of the bore of the hub receiving the shaft of a rotor takes place, and with regard to the contact surface of the carrier body, planarization and optionally pretreatment with regard to the subsequent application 54 of the ring disk takes place. The ring disk is preferably carbon-containing or consists entirely of sintered carbon, which has the morphology and granularity required in terms of electrical conductivity, abrasion resistance and resistance. The inner diameter of the ring disk is preferably larger than the diameter of the bore in the hub. The ring disk and the carrier body are then divided 55 into segments, preferably by a single machining operation, for example by grinding or sawing. The separation slot extends through the ring disc and the bottom of the cup-shaped

Carrier body into the molding compound adjoining the carrier body and resting thereon. The separation of the segments of the commutator takes place in electrical terms, ie. H. the electrically conductive connections between the segments are severed. The segments are still mechanically connected to each other via the molded hub.

Finally, the carrier body 56 is coated with a material which is resistant to the reaction-promoting environment, for example with tin, silver or chromium, in a layer thickness of 0.1 to 10 μm, preferably 1 to 3 μm. In this case, preferably all of the exposed surfaces of the carrier body are coated, in particular the surfaces of the metallic segment supporting parts which are exposed by dividing the carrier body. The coating is preferably carried out by electroless deposition from a solution or suspension, ie without external tension being applied between the support body to be coated and the solution or suspension. Before the actual coating, chemical and / or mechanical cleaning, for example in an ultrasonic bath, is carried out to remove impurities and to remove residues on the surface of the segment supporting parts and to prepare the surface for coating. The segment supporting parts, which essentially contain copper, can then be pretreated in a reducing atmosphere. The actual coating is preferably carried out at a temperature which is higher than the room temperature. In appropriate solutions or suspensions, for example, with deposition times of less than one hour, layer thicknesses between 1 and 3 m can be achieved. A large number of commutator elements can be coated in one operation. After coating, the commutators are rinsed and dried.

2 shows a second embodiment of the manufacturing process. After the injection molding 152 of the carrier body, the carrier body is divided into segment carrier parts 155A, forming the hub.

The segment support parts are then coated 156 as described above. Alternatively, the coating can also be carried out galvanically or electrolytically, for example with silver in a layer thickness of approximately 5 μm. The washer is then applied 154 and finally divided 155B into ring segments. The separating slots in the annular disk are preferably narrower or the same width, at least within these, compared to the separating slots in the carrier body. As an alternative or in addition to the coating 1 56 of the segment support parts immediately after the separation 155A of the carrier body, the segment support parts can also be coated only after the separation 155B of the ring disk into ring segments, as described above. FIG. 3 shows a top view of the segmented annular disk of a commutator 1 produced by the method according to the invention, and FIG. 4 shows a section IV-IV through the commutator 1 of FIG. 3.

The washer is divided into eight ring segments 2, as well as the

Carrier body is divided into eight segment supporting parts 4. The hub 6 formed by injection molding is formed on the segment supporting parts 4 of the carrier body and forms a central bore 6a for receiving a shaft (not shown) of a rotor of a motor or a generator. The segment support parts 4 have a hook 4b on their outer peripheral surface 4a for the electrical connection of a rotor winding. In addition, the segment support parts 4 each have at least one anchor element 4c for the fixed connection to the hub 6. The diameter of the outer peripheral surface 4a corresponds to the outer peripheral surface 2a of the ring segments 2 formed from the ring disk. The diameter of the inner peripheral surface 2d of the ring segments 2 essentially corresponds to the inner peripheral surface 4d of the segment supporting parts 4 or is slightly larger.

The connection and in particular solder layer 10 between the

Segment support part 4 and the ring segment 2 is 50 μm thick, for example. When dividing the ring disk and the carrier body, separation slots 12 are formed which protrude into the area of the hub 6. The surfaces 14 of the segment support parts 4, which are essentially made of copper, are exposed by dividing the carrier body and are covered with a coating that is resistant to the reaction-promoting environment. The outer peripheral surface 4a and the hooks 4b of the segment supporting parts 4 are also preferably coated. This enables a better connection of the segment support parts with the rotor windings, in particular easier contacting of the Segment supporting parts over the outer peripheral surface 4a when welding the winding ends to the hooks 4b. In contrast, preferably neither the flat surfaces 2b serving as the brush running surface nor the surfaces 2c of the ring disk which are exposed due to the division are coated. The connecting layer 10 between the segment supporting parts 4 and the ring segments 2 is coated both on their surfaces 10b exposed by the parting and on their inner and outer peripheral surface 10a.

The separation slot shown enlarged in FIG. 5 compared to FIG. 4 was produced in one operation by grinding or sawing the composite of hub 6, the carrier body forming the segment supporting parts 4 and the ring disk forming the ring segments 2. The slot is typically a few tenths of a millimeter wide and a few millimeters deep. In particular by coating by means of electroless deposition from a solution or suspension containing, for example, tin, a sufficiently resistant, thick and dense selective coating of the surfaces 14 of the segment supporting parts 4 and optionally the connecting layer 10 exposed by the separation can be achieved. FIG. 6 shows a view corresponding to FIG. 5 of a commutator manufactured according to the alternative manufacturing method according to FIG. 2. The carrier body was first divided into the segment supporting parts 104 with a first, wider) slot 1 12a, then the washer was applied by means of the connecting layer 1 10 and finally the washer through a second, narrower slot 1 12b aligned with the first into the ring segments 102 divided. The coating (not shown) of the surfaces 1 14 exposed by the division of the segment supporting parts 104 and optionally the exposed surface 1 10 b of the connecting layer 1 10 can either be in front of or after applying the ring washer. Alternatively, the connection layer 1 10 may not end flush with the ring segments 1 02, but flush with the segment supporting parts 104.

Claims

Patent claims

1 . Method for producing a flat commutator (1), in which a carrier body which forms metallic and segmental support parts (4; 104) is provided (52; 152) with a hub (6) formed from an electrically insulating material, - with a resistant in a reaction-demanding environment

Ring disc (54; 154) is electrically connected and mechanically fixed, is divided into segment support parts (4; 104) (55; 155A), the ring disc is divided into ring segments (2; 102) (55; 155B), and by the Parts of the carrier body exposed surfaces of the metallic segment support parts are coated with a coating resistant to the environment, characterized in that - the coating is carried out by electroless plating.

2. The method according to claim 1, characterized in that the deposition takes place from a solution or suspension.

3. The method according to claim 1 or 2, characterized in that the annular disc (54; 1 54) contains carbon.

4. The method according to any one of claims 1 to 3, characterized in that the carrier body is divided into segment support parts (4; 104) after connecting to the washer, in particular that the dividing of the washer and the part of the support body in one step, preferably by cutting or sawing the composite of the carrier body and the ring disk.

5. The method according to any one of claims 1 to 4, characterized in that the coating is carried out selectively only on the surfaces of the segment supporting parts (4; 104).

6. The method according to any one of claims 1 to 5, characterized in that the coating is carried out with tin, silver or chrome.

7. The method according to any one of claims 1 to 6, characterized in that the layer thickness is between 0.1 and 10 microns.

8. commutator manufactured according to a method according to any one of claims 1 to 7, characterized in that the hub (6) abuts the support body in the region of the division.

9. commutator according to claim 8, characterized in that the hub (6) forms a complete cover of a cylindrical boundary surface of a central bore (6a) of the carrier body for receiving a shaft of a rotor of a motor or a generator.

10. Electric motor for driving a fuel pump with a

Commutator manufactured according to a method according to one of claims 1 to 7, characterized in that the currentless and preferably deposited from a solution or suspension Coating is resistant to a fuel obtained from renewable raw materials.