JP2007511993A - Fuel pump - Google Patents

Abstract

  The present invention includes an electric motor-type drive device including a collector (20) and carbon brushes (24, 26) that sequentially come into contact with the collector segments (16, 18) when the collector (20) rotates. Related to the fuel pump. For improved corrosion resistance and cleaning of the carbon brushes (24, 26), the collector segments (16, 18) have graphite and at least one collector segment (16, 18) has a higher hardness than graphite. It was made to have graphite with an additive consisting of material (30).

Description

  The present invention relates to a fuel pump provided with an electric motor type driving device including a collector and a carbon brush that sequentially contacts the collector segment when the collector rotates.

  This type of fuel pump is known. This type of fuel pump is particularly used in automobiles and serves to pump fuel from a fuel container to a carburetor or injector of an internal combustion engine. In this case, the electric motor type driving is performed by an electric motor provided with a collector, that is, a so-called “commutator motor”. A collector, also called a current reverser or commutator, is a cylindrical component coaxially installed on the shaft of the commutator motor and consists of a copper plate having an insulating interlayer and forming a segment. ing. A so-called “armature coil” is connected to the copper plate. The collector, which is made of copper wire cloth or carbon, is rubbed into contact with a current supplying brush.

  A disadvantage of this commutator motor is the wear that reduces the life of the motor. This wear is caused by the formation of a significant oxide layer on the collector surface. Particularly strong oxide formation, and thus considerable wear, is carried out in motors working in an environment surrounded by fuel. In order to combat wear, it is known to provide a polishing device (Putzvorrichtung) in addition to or integrated with the carbon brush. The polisher should cause wear of the oxide layer formed on the surface of the collector during collector rotation. The cleaning of the carbon brush is neither thought nor intended.

  In a special embodiment of a fuel pump for a specific fuel, a carbon collector is used instead of a copper collector. This means that the copper segment is not used for the collector, but the carbon segment is used for the collector. In particular, in the context of alcohol-containing fuels, which have the property of becoming electrically conductive over time, the disadvantage is that corrosion products are deposited on the sliding surface of the carbon brush by an electrochemical process. .

  The object of the present invention is therefore to improve the fuel pump of the type mentioned at the outset and to keep the sliding surface of the carbon brush free of corrosion products.

  This problem is solved according to the invention by the fact that the collector segment comprises graphite and at least one collector segment comprises graphite with an additive made of a material having a higher hardness than graphite.

  Due to the use of graphite, the collector of the electric motor for driving the fuel pump according to the invention is extremely corrosion resistant, especially in an environment surrounded by fuel containing alcohol. This has a very positive effect on the life of the fuel pump. Particularly advantageously, the cleaning of the carbon brush applied to the carbon segment is achieved during the operation of the fuel pump by simultaneously adding a relatively hard material. That is, ablation of corrosion products deposited on the sliding surface of the carbon brush, more specifically, the carbon brush, i.e., scratching and fine cutting, is performed with the added material. The added material thereby leads to the desired increased abrasive wear by the collector of corrosion products on the carbon brush. No additional polishing equipment or specially formed carbon brushes are required for this purpose.

  It is conceivable that the material to be added is provided in the graphite, for example in the form of a strip-like solid material. In contrast, a particularly good cleaning of the carbon brushes and a simple and inexpensive production of the collector segments is achieved in another advantageous configuration of the invention if the added material is present in the graphite in the form of individual particles. Is done.

  In this case, it is advantageous if the cleaning of the carbon brush in the entire area of the abutment surface of the collector is an additional advantageous configuration according to the invention, in which the particles are made of a material that is evenly harder than graphite. It is obtained when it is distributed in the respective collector segments, ie one or more collector segments, with graphite having an object.

  In principle, there is no restriction on the choice of added material. However, as experiments with the fuel pump according to the invention show, in another advantageous configuration of the invention, it has been found to be particularly advantageous when the material added is aluminum oxide.

  In order to have as little adverse effect as possible on the electrical properties of the carbon brush / collector segment pair despite good cleaning action, it has an additive made of a material having a higher hardness than graphite It has been found advantageous when the proportion of material added in the respective collector segment with graphite, ie the collector segment or segments, is about 0.2%.

  An especially particularly slim construction type of the electric drive of the electric motor of the fuel pump is another advantageous configuration of the invention, in which the collector segment is oriented radially with respect to the collector axis and the carbon brush is axial. It is obtained when applied to the collector segment. The collector segment is then arranged on the end face of the collector where the carbon brush is pressed in the axial direction.

  In another advantageous configuration of the invention, the collector segment is oriented axially with respect to the collector axis and a carbon brush is applied to the collector segment in the radial direction. Thereby, the drive unit of the fuel pump can be formed extremely short and flat.

  Due to the rotation of the collector and the rubbing contact of the carbon brush on all the collector segments resulting from this rotation, a remarkable cleaning of the carbon brush is already added, one collector segment or a few collector segments. This can be achieved simply by having a relatively hard material. On the other hand, in order to clean the carbon brush particularly effectively while avoiding collector imbalance, in another advantageous configuration of the invention, all collector segments in contact with the carbon brush are added. It is advantageous to have the material.

  An embodiment of the invention is shown in the drawing and will be described in detail below. In that case, the only drawing shows a sectional view of the rotor of the fuel pump.

  The drawing shows a rotor 1 of a commutator motor, which is not shown otherwise, of a fuel pump. The rotor 1 having the rotor shaft 2 rotates around the rotor axis 4 when the fuel pump is operated. The rotor 1 is provided with a rotor winding 6. End portions of the rotor winding 6 are electrically connected to the connection portions 8 and 10 of the contact lugs 12 and 14.

  Furthermore, collector segments 16, 18, preferably made of graphite, of the collector 20, which are coaxially mounted on the rotor shaft 2, are connected to the contact lugs 12, 14. Thereby, the collector segments 16, 18 are electrically connected to the rotor winding 6. The collector segments 16, 18 of the collector 20 are oriented radially with respect to the collector axis that is aligned with the rotor axis 4 and away from the collector axis. When the rotor 1 implied by the arrow 22 is rotated, and thus the collector 20 is rotated, the carbon brushes 24 and 26 preloaded by a spring device (not shown) are brought into sliding contact with alternative collector segments. Therefore, during one rotation of the rotor 1, for example, the upper collector segment 16 as viewed in the drawing and the lower collector segment 18 as viewed in the drawing slide along the upper carbon brush 24 as viewed in the drawing.

  As can be further seen, the collector segments 16, 18 have an additive consisting of particles 28. The particles 28 are evenly distributed in the collector segments 16, 18 and are made of an aluminum oxide material 30. For clarity, the particles 28 are shown in an exaggerated size compared to the collector segments 16, 18.

It is sectional drawing of the rotor of a fuel pump.

Claims (8)

  In a fuel pump including a collector and an electric motor type driving device including a carbon brush that sequentially contacts the collector segment when the collector rotates, the collector segment (16, 18) has graphite. A fuel pump, characterized in that at least one collector segment (16, 18) comprises graphite with an additive consisting of a material (30) having a higher hardness than graphite.   2. The fuel pump according to claim 1, wherein the added material (30) is present in the graphite in the form of individual particles (28).   3. The fuel pump according to claim 2, wherein the particles (28) are evenly distributed in the respective collector segments (16, 18).   The fuel pump according to any one of claims 1 to 3, wherein the material (30) to be added is aluminum oxide.   The fuel pump according to any one of claims 1 to 4, wherein the proportion of the material (30) added in each collector segment (16, 18) is about 0.2%.   The collector segment (16, 18) is oriented radially with respect to the collector axis and the carbon brush (24, 26) is axially applied to the collector segment (16, 18). The fuel pump according to any one of the above.   6. The fuel pump according to claim 1, wherein the collector segment is oriented axially with respect to the collector axis, and the carbon brush is applied to the collector segment in the radial direction.   8. The fuel pump according to claim 1, wherein all collector segments (16, 18) in contact with the carbon brushes (24, 26) have added material (30).

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