DE102008004378A1 - Forging disk for electric motor of in-tank electrical fuel pump for supplying fuel to e.g. diesel engine, has metallic layer produced from metal particles, where metallic particles are fixedly connectable with one another by binder - Google Patents

Abstract

The disk (410) has a metallic layer (414) fixedly connected with a graphite layer (412), where the metallic layer is produced from metal particles. The metallic particles are fixedly connectable with one another by a binder. The graphite layer is produced from graphite particles, which are fixedly connected with one another by the binder. The graphite layer and the metallic layer are fixed to each other and/or connected with one another by a fuel process, where the fuel process is implemented at a temperature of approximately 200 degree Celsius to approximately 1000 degree Celsius. An independent claim is also included for a method for manufacturing a forging disk for a collector of an electric motor.

Description

The The invention relates to a two-component disk and to a method for manufacturing such a two-component disk. In particular, the invention relates to a Two-disc disk for a collector of an electric motor, preferably an electric motor of a fuel pump, and a corresponding Method for producing the two-disc disk for a such collector. Moreover, the invention relates to a Collector, an electric motor and / or a fuel pump with a two-component disk according to the invention.

at Many applications of graphite are beneficial and sometimes even necessary, the graphite. thermally and electrically well conductive with a metal body, for. B. of a copper material, too connect or attach to this. This can be, for example the case for pantographs for pantographs, Earthing contacts, graphite linings in reactors and electrical Contacts, such as B. an armature or a collector of an electric motor, be.

in the Prior art are such compounds or fasteners usually produced by a solder joint, wherein a surface of a graphite body consuming must be pretreated to anchor a solder in the graphite body to reach and so the graphite body with the metal body to be able to connect.

From the DE 198 56 503 C1 It is known to press a green compact made of a highly graphite-containing material, which contains a curable binder, with a high-metal-containing layer. The resulting two-substance green compact is applied with its high metal-containing layer on a Metallkörpergrün ling and sintered together with this. In this case, the binder cures in the graphite-containing part of the two-substance body green compact or glued to the graphite, whereby a solid, mechanically resistant two-substance body is formed, which is firmly connected to the metal body.

adversely Here is that a production of the metal body zusammengesintererten binary body not easy on different, distant production sites can be split. To make matters worse, that a transport and warehousing of the relatively less resistant two-substance body green not unproblematic. In addition, such is one Two-substance body not solderable, so for its attachment to the metal body a sinterable Metallkörpergrünling is needed.

Further is known in the art for a collector of a motor anchor, in particular a fuel pump, a two-component disc of graphite and Copper powder used, wherein the graphite powder mixed with a binder is. The graphite and the copper powder are in two layers pressed together into a disk, and in a subsequent Burning or sintering of the disc at temperatures of about 300 ° C, increases the strength of the resulting graphite composite in that the binder melts and binds the graphite powder. The Copper powder of the disc sintered at such a temperature only insignificant, resulting in the strength of the copper powder layer essentially determined by the previous pressing operation and low.

at a further processing (soldering, slitting) such Two-disc disks of graphite and copper z. B. to a collector An electric motor can crack in the copper layer or in a transition region between the copper to Graphite layer occur. As a result, the collector and optionally the entire motor armature unusable.

It It is an object of the invention to provide an improved two-layer disk, in particular for a collector of an electric motor, preferred an electric motor for a fuel pump, as well as a Specify a method for producing such a two-component disc. Furthermore, it is an object of the invention to provide a mechanically resistant To provide molded body, which with a metal body reliable thermally and electrically good conductive is connectable without it a complex pretreatment of a surface requires the molding.

According to the invention in particular in a further processing of the two-disc or the Form body be reduced cracking. Furthermore, should the two-component disc or the molded body simple and efficient to be finished, it being preferred, such inventive Two-layer disc or such a shaped body according to the invention to be produced externally by one manufacturer, without one Transport of the two-disc or the molding special To take precautions.

The The object of the invention is achieved by means of a two-component disk (molding), in particular a two-disc disk for a collector an electric motor according to claim 1; through a Method for producing such a two-component disk according to claim 4; and a collector, an electric motor or a fuel pump solved according to claim 13.

The two-component disk according to the invention has at least two layers, a graphite and a metal layer on. In the text which follows, a two-component disk is to be understood as meaning an arbitrarily shaped two-material body which may optionally contain further main components, that is, apart from a binder and / or an additive, etc. The metal layer of the two-component disk according to the invention has metal articles which can be firmly connected to one another by means of a binder.

in this connection it is inventively preferred that the metal layer Copper or consists mainly of copper. The same applies to the graphite layer, the graphite or consists mainly of graphite. In preferred embodiments According to the invention, the graphite layer comprises graphite particles which are firmly connected to each other by means of a binder. According to the Invention, the graphite particles of the graphite layer and the Metal particles of the metal layer by a firing process with each other connected. This is a binder, at least in the metal layer, however, also in the graphite layer, it prefers an increase the strength between respective particles.

According to the invention uses a suitable metal or copper binder mixture, which the stability of the metal layer within the two-component disk elevated. Ie. it becomes the metal powder and preferably too the graphite powder is mixed with a suitable binder, which stability at a certain temperature of the firing process the respective layer, as well as a stability of a transition region improved between the graphite and the metal layer.

The The inventive method has the following Steps to: Mixing a binder with a metal powder and Producing a metal layer. Here it is possible that the metal powder and the binder adhere to each other. This is z. B. at least partially coated with the binder or coated metal powder of the case; d. H. in certain embodiments The invention can be a mixing of the binder with the metal powder omitted so that the metal powder outside of the Particles already has the binder. Subsequently to the Production of the metal layer, this is done with a graphite layer pressed.

chronologically after compression, burning of the metal and graphite layers takes place the shaped body or the entire molded body instead, with a temperature of the firing process chosen such that the binder melts the metal layer. Should the graphite layer also have a binder, it is preferred that this at the firing temperature also melts. Afterwards the manufacturing process of the two-disc, this can with their Metal side soldered to a collector or a motor armature become.

According to the invention the metal or copper powder before pressing to the two-disc a suitable binder mixed, or the metal or the copper powder already has this. This results in an increase the mechanical strength of the two-disc, in particular Cracks in the metal layer of the two-component disk are avoided. This is z. B. for two-layer carbon slices for Collectors or for motor armature of electric motors relevant.

This Binder must melt at the temperature of the firing process. The during the melting process resulting bridges between the individual metal or copper particles increase the Strength of the respective layer. Furthermore, it is preferred according to the invention that the binder has an electrical and also a thermal conductivity of the Two-component disk substantially not adversely affected.

In preferred embodiments of the invention becomes a maximum temperature of the firing process selected such that the graphite powder the graphite layer at least partially sintered. Is preferred also that in this case the metal or the copper at least in the approach sintered. A holding and / or maximum temperature of the firing process is in principle freely selectable, as long as sufficient strength the two-disc is guaranteed. The temperature of the firing process depends mainly after the two binders melt.

In preferred embodiments of the invention is a Holding or maximum temperature of the firing process between 250 ° C and 400 ° C. Particularly preferred is a temperature of about 300 ° C. Further, it is preferable that a melting temperature the binder for the metal or the copper layer not too strong of a melting temperature of the binder for the Differs graphite layer. In preferred embodiments The invention is a difference of these two temperatures not more than 130 ° C. Further, it is preferable that a difference these two temperatures are less than 50 ° C to 20 ° C is.

One Binder of the metal or copper powder, and a binder of the graphite powder may be a metal, a metal alloy and / or a plastic. in this connection The binders of the two powders can also be identical or similar be constructed.

In preferred embodiments of the invention, a binder of the graphite powder is a plastic, in particular a thermoset or a thermosetting plastic. Here, the polyphenylene sulfide having a melting point of about 285 ° C is preferred. In preferred embodiments of the invention, the binder of the metal or copper powder is a metal, a metal alloy or a solder. Preference is given here to a binder which comprises lead, bismuth, indium and / or selenium. Most preferably, the binder comprises tin. Here, the tin can be high-alloyed in pure form or used as part of a metal alloy.

Of the preferred binder tin melts below 300 ° C and can the for increasing the strength of the two-disc disk train required bridges. Furthermore, tin influences the electrical and thermal conductivity of the metal or copper layer not negative, so that a corresponding Ko does not change significantly. Here is a mixing ratio of metal or copper and the binder tin to choose such that in addition to the desired increase in strength of the two-disc, the electrical and / or thermal resistance of the metal or copper layer does not rise and subsequent process steps, such. B. soldering the two-disc, not be affected.

tin as binder or tin-coated metal or copper powder are here only explained in more detail by way of example. It is according to the invention Use of any binder conceivable, the at least one of the above Properties fulfilled. Furthermore, it is depending on one Field of application of the two-component disc possible through the use of a suitable binder to increase the mechanical Strength, as a side effect even more positive properties achieved can be.

This is z. B. possible with the use of copper and the binder tin, whereby reducing the "free" copper in the Dual disc, unwanted reactions are avoided can. This concerns z. B. electric motors for Fuel pumps, whereby by reducing the "free" copper in the copper layer, unwanted chemical reactions can be avoided with the fuel. About that In addition, this is an oxidation tendency of a copper surface the two-disc has been greatly reduced, so you do not reject more in further processing, especially in relation to one Solderability, has more.

additional Embodiments of the invention will become apparent from the others dependent claims.

The Invention will be described below with reference to an embodiment with reference to the accompanying drawings closer explained. In the drawing show:

1 a schematic cross-sectional view of a two-stage electric fuel pump; and

2 a two-disc according to the invention for the electric fuel pump 1 ,

There is often the desire graphite parts such. As graphite disks or graphite blocks, electrically and thermally good conductive to connect with a metallic body. Such compounds or fasteners are usually made by a solder joint. In order to achieve anchoring of the necessary solder on the graphite material, it is necessary to pretreat a graphite surface accordingly. In the following, a way will be described with reference to an exemplary embodiment, such a graphite surface or a two-substance body according to the invention 410 that also as a molded body 410 or composite part 410 can be designated to produce.

The invention will be described below with reference to a two-component disk 410 or on the basis of a two-substance body 410 for a collector 400 a motor anchor 300 an electric motor operated, two-stage fuel pump 1 explained in more detail. However, the invention is not limited to such an embodiment but is applicable to all fuel pumps 1 or all electric motors 10 applicable. In addition, the invention has a wide applicability and is quite generally applicable to electrical contacts and / or graphite components, such as. B. for grinding bar, for grounding contacts, for graphite linings etc.

In the 1 illustrated electric fuel pump 1 supplies a combustion engine with fuel in all its operating conditions 2 , Such electric fuel pumps 1 increasingly serve as a prefeed pump for modern direct injection systems, both for gasoline and diesel engines. The electric fuel pump 1 promotes the fuel 2 continuously from a fuel tank, and may be installed directly in the fuel tank or in a fuel line. Today, Intank electric fuel pumps are usually used 1 used, which are integrated in tank installation units and also contain a level sensor and a swirl pot for the separation of vapor bubbles from a fuel return.

In the 1 illustrated two-stage electric fuel pump 1 has one as a side channel pump 100 trained precursor 100 , one as internal gear pump 200. trained master class 200. , a check valve 500 , an electrical connection preferably accommodated in a connection cover 600 and as an electric motor drive 10 on.

The electric motor 10 the fuel pump 1 has a motor anchor 300 and one provided as a plan collector 400 trained collector 400 on. Furthermore, the electric motor 10 an am collector 400 via a sliding contact ansitzende brush 420 on. Brush side, the collector points 400 who also works as a commutator 400 can be designated, a two-disc 410 on which an electrical connection between the brush 420 and the rest of the collector 400 or the remaining motor armature 300 ensures.

The at the collector 400 preferably provided via a solder joint Zweistoffscheibe 410 is in 2 shown in more detail, wherein in 2 the rest of the collector 400 is omitted. The two-component disk according to the invention 410 is made up of two layers 412 . 414 built up. Here are the two layers 412 . 414 more or less discreet in each other and have a common transition area 413 , The transition area 413 can be formed arbitrarily and separates the two layers 412 . 414 in any area / section within the two-component disk 410 , In the present embodiment of 2 is the layer 412 about two to three times as thick as the layer 414 , According to the invention, any layer thicknesses and also partial overlaps of the layers 412 . 414 applicable.

According to the invention, one of the two layers 412 a graphite layer 412 and the other layer 414 a metal layer 414 , Here, it is preferable that the metal layer has a metal content of at least 50% (weight) and the graphite thickness 412 has a graphite content of at least 50% (weight). A preferred metal here is copper, so that subsequently of a copper layer 414 the speech is.

For a production of the two-component disk according to the invention 410 the graphite 412 and the copper layer 414 pressed together and then subjected to a firing process, whereby it is possible, the firing process when pressing the two layers 412 . 414 make. According to the invention, the graphite layer settles 412 in large part from a graphite powder and the copper layer 414 in large part composed of a copper powder, wherein the copper may also be a component of metal alloy.

In order to further facilitate sintering of the graphite particles in the firing process and to improve the fixing of the copper particles in the copper layer, both the graphite powder and the copper powder are each mixed with a binder. In this case, the respective binder is chosen such that it at least partially melts during the firing process and preferably an electrical and / or thermal conductivity of the later two-disc 410 not too strongly negatively affected.

In a preferred embodiment of the invention is the Binder of graphite powder a thermo or a thermoset. Prefers is the binder polyphenylene sulfide which is a high temperature resistant, thermoplastic is. Polyphyllenesulfid (PPS) has a melting point of less than 300 ° C, has good mechanical Properties even at temperatures over 200 ° C, allows continuous use depending on the load up to 240 ° C and has a very good chemical resistance against almost all solvents, many acids and bases. It is natural according to the invention possible, another suitable binder for that To use graphite powder.

Based on the binder of the graphite powder, a binder is mixed with the copper powder, which has a melting point similar to the binder of the graphite powder. It is possible to use the same or a different binder. In preferred embodiments of the invention, the binder of the copper powder is for the copper layer 410 a metal or a metal alloy.

In particular, tin or a tin-containing binder is used. Tin melts as well as PPS under a preferred firing temperature of 300 ° C and can be used to increase the strength of the two-component disk according to the invention 410 train required bridges. According to the invention, a mixing ratio of copper and tin is chosen such that in addition to the increase in strength of the electrical and / or thermal resistance of the resulting copper layer 414 or the entire two-component disk 410 does not increase too much and preferred subsequent process steps are not affected. In addition to mixing a copper powder with the tin binder, it is possible to use tin-clad copper powder.

An inventive approach in producing the two-disc 410 can look like this. A pressing tool is filled in two steps with preferably two independent filling devices. By a filling device, the graphite is first filled with its binder in the pressing tool and then the copper with his. Binder laid over it. Thereafter, this filling is pressed in the pressing tool with a certain pressure to a two-layer part, a so-called green body.

It is also possible according to the invention, first a graphite green body and / or a metal or copper green produce and then to press together. Furthermore, it is possible according to the invention to pre-press a graphite green, metal or copper powder to sprinkle and compress or compress both.

After pressing the graphite layer 412 with the copper layer 414 becomes the resulting two-disc discard 410 burned, whereby the two-component disk according to the invention 410 results. Now the two-disc can 410 at the collector 400 z. B. be provided by means of a solder joint.

The invention is not limited to dual-disc disks 410 applicable, but on all bodies, moldings or composite parts. Ie. with the inventive concept two-disc 410 should be arbitrarily shaped two-piece body, molded body and / or composite parts.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 19856503 C1 [0004]

Claims (14)

Two-disc disc for a collector ( 400 ) of an electric motor ( 10 ), in particular an electric motor ( 10 ) a fuel pump ( 1 ), with a graphite layer ( 412 ) and one with the graphite layer ( 412 ) firmly bonded metal layer ( 414 ), wherein the metal layer ( 414 ) is made of metal particles and a binder, by means of which the metal particles are firmly connected to each other. Two-component disk according to claim 1, wherein the graphite layer ( 412 ) is made of graphite particles and a binder, by means of which the graphite particles are firmly connected to each other. Two-layer disc according to claim 1 or 2, wherein the graphite layer ( 412 ) and the metal layer ( 414 ) are fixable to each other by a firing process or can be connected to each other. Method for producing a two-component disk ( 410 ), in particular for a collector ( 400 ) of an electric motor ( 10 ) comprising the following steps: adding a binder to a metal powder and producing a metal layer ( 414 ), Pressing the metal layer ( 414 ) with a graphite layer ( 412 ) and firing the layers pressed together ( 412 . 414 ) at a temperature at which the binder of the metal layer ( 414 ) melts. Method according to claim 4, wherein the metal layer ( 414 ) on the preferably pre-compressed graphite layer ( 412 ) is produced. Two-layer disc or method according to one of claims 1 to 5, wherein the temperature of a firing process is selected such that a graphite powder of the graphite layer ( 412 ) at least partially sintered, and / or the temperature of the firing process is selected such that a binder of the graphite layer ( 412 ) melts. Dual disc or method according to one of Claims 1 to 6, wherein the burning process at a temperature from about 200 ° to about 1000 ° C, in particular of about 250 ± 10 ° C to about 600 ± 25 ° C, preferably about 280 ± 10 ° C to about 475 ± 25 ° C, more preferably about 300 ± 5 ° C to about 400 ± 20 ° C or particularly preferably about 320 ± 10 ° C to about 350 ± 10 ° C is performed. Two-layer disc or method according to one of claims 1 to 7, wherein a melting temperature of the binder for the metal layer ( 414 ) substantially in a range of a melting temperature of the binder for the graphite layer ( 412 ), and less than about 200 ± 50 ° C, especially less than about 100 ± 25 ° C, preferably less than about 75 ± 10 ° C, more preferably less than about 50 ± 10 ° C or especially especially preferably less than about 30 ± 5 ° C deviates from it. Two-layer disk or method according to one of claims 1 to 8, wherein the binder of the metal layer ( 414 ) is added to the metal particles or the metal powder in such a way that the binder at least partially sheathed. Two-layer disk or method according to one of claims 1 to 9, wherein the binder of the metal particles or the metal powder is selected such that an electrical conductivity of the two-disc ( 410 ) remains essentially unchanged. Two-component disk or method according to one of claims 1 to 10, wherein the binder of the metal particles or the metal powder tin, lead, bismuth, indium and / or selenium has, or the binder of the metal powder, a metal alloy or a lot is. Two-component disk or method according to one of claims 1 to 11, wherein the binder of the graphite particles or the graphite powder is a plastic, in particular a thermal or a thermoset, preferably polyphenylene sulfide, is. Two-layer disk or method according to one of claims 1 to 12, wherein the metal layer ( 414 ) Copper has. Collector, electric motor or fuel pump, with a two-disc ( 410 ), wherein the two-disc ( 410 ) a two-disc ( 410 ) according to one of claims 1 to 12, or the two-component disk ( 410 ) is produced by a method according to any one of claims 4 to 13.