| Title of Invention | CARBON BRUSH HOLDER FOR AN ELECTRODYNAMIC MACHINE |
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| Abstract | Carbon brush holder for an electrodynamic machine. The invention relates to a carbon brush holder for an electrodynamic machine, in particular an electric motor, having a carbon brush guide (3) which is in the form of a cartridge and is arranged in a housing (2), for mounting a carbon brush (4) which can be displaced in a guide direction (F), the carbon brush guide (3) having separate guide elements in the form of a first shell element (8) and a second shell element (9), which each extend along the guide direction (F), and to an electric motor for a domestic appliance having such a carbon brush holder (1). The first shell element (8) is formed from an electrically insulating material, and the second shell element (9) is formed from metal. |
| Full Text | PCT/EP2006/067031 / 2005P01959WOCN 1/9 Carbon brush holder for an electrodynamic machine The invention relates to a carbon brush holder for an electrodynamic machine, in particular an electric motor, having a cartridge-type carbon brush guide which is arranged in a housing for the purpose of mounting a carbon brush which can be displaced in a guide direction, the carbon brush guide having separate guide elements in the form of a first shell section and a second shell section, each of which extends along the guide direction. A carbon brush holder of this kind is known already from EP 1 117 160 B1, which discloses a carbon brush guide consisting of metal and being composed of two identical half-shells which extend along the wider surfaces of the carbon brush symmetrically relative to the symmetry plane of the carbon brush. However, a carbon brush holder of this type has the disadvantage that when multilayer carbon brushes are used precautions must be, taken in order to avoid crossover currents flowing across the metallic carbon brush guide between the carbon rods of the multilayer carbon brush which are separated by means of an insulating layer. This is achieved according to EP 1 117 160 B1 in that the metallic half-shells do not completely enclose the multilayer carbon brush and do not extend along those sidewalls of the multilayer carbon brush in which the carbon bars come into contact with one another with the intermediate insulating layer. The object underlying the present invention is to provide an improved, inexpensive carbon brush holder for an electrodynamic machine. The aforementioned object is achieved by means of a carbon brush holder having the features of claim 1. Advantageous and preferred embodiments of the invention are the subject matter of the dependent claims. According to the invention, in a carbon brush holder of the type cited in the introduction the first shell section is embodied from electrically insulating material and the second shell section is embodied from metal. This is based on the inventive knowledge that it is ensured already by means of the one metallic second shell section that the carbon brush is guided precisely, such that a continuous areal contact of the carbon brush on a commutator or a collector ring of an electrodynamic machine is ensured. Furthermore the metallic second shell section has the advantage that heat is dissipated by it and consequently an overheating of the carbon brush is avoided. In the case of a multilayer carbon brush the electrically insulating material of the first shell section prevents leakage currents from flowing by way of PCT/EP2006/067031 / 2005P01959WOCN 2/9 the carbon brush guide between the carbon bars that are separated by means of an insulating layer. A further advantage consists in the fact that if a spring element which acts on the carbon brush and presses the carbon brush onto the commutator or the collector ring is provided, an electrical insulation can be dispensed with, and if a plug-in connector part for electrical contacting of the carbon brush is provided, an electrical insulation can be dispensed with also in the case of multilayer carbon brushes. All in all, the commutation is improved compared with prior art carbon brush holders, as a result of which the service life of the carbon is extended. This means that the length of carbon can be reduced while maintaining the same longevity of the carbon brush. Preferably the first shell section is embodied in particular from heavy-duty plastic such as Duroplast, for example. Particularly preferred is a plastic with a low coefficient of thermal expansion, for this enables the first shell section to be manufactured with a high degree of dimensional stability. Duroplast retains its strength and shape even at high temperatures, with the result that the carbon brush is also guided precisely by the first shell section even at high temperatures. According to a preferred embodiment the first shell section is integrally molded onto the housing of the carbon brush holder as a single piece. This reduces the number of component parts and in addition there is no need to adjust the first shell section, as a result of which the carbon brush holder can be manufactured economically. The first shell section can be manufactured together with the housing particularly easily by means of an injection molding method. The second shell section is preferably shaped from a sheet metal, which means that it can be produced particularly easily, by stamping and bending for example. In particular the second shell section has at least one latching element by means of which it can be fixed in the housing. In particular a receptacle for retaining the second shell section is embodied in the housing, such that the position of the second shell section in the housing is predefined. In this way inaccuracies in the positioning of the second shell section in the housing of the carbon brush holder are avoided, thereby enabling a precise guiding of the carbon brush to be ensured. In a development of the invention it is provided that the housing has at least one opening which extends in the guide direction and which can be closed by means of a cover plate. The interior of the housing can be accessed particularly easily through the opening, which PCT/EP2006/067031 / 2005P01959WOCN 3/9 preferably extends over the entire length of the housing, thereby considerably simplifying the assembly of the different component parts of the carbon brush holder including the carbon brush. In particular the cover plate has at least one latching element by means of which the cover plate can be snapped into place with the housing, with the result that a time-consuming and expensive screwed connection can be dispensed with. According to a preferred embodiment a receptacle for retaining the second shell section is embodied on the cover plate, such that the second shell section can be fixed in the housing by means of the cover plate. In this way the position of the second shell section in relation to the housing and in relation to the cover plate can be precisely predefined, thus removing the need for further calibration. Preferably, positioning elements are integrally molded on the cover plate and/or fixing elements integrally molded on the housing for the purpose of, respectively, positioning and mounting the carbon brush holder on the electrodynamic machine. This makes a precise installation on the electrodynamic machine particularly easy and possible with as few additional component parts as possible. In a development of the invention it is provided that the second shell section is arranged in the housing opposite the first shell section, with in particular the first shell section and the second shell section being embodied for guiding opposite side surfaces of the carbon brush. Preferably the first shell section and/or the second shell section in each case grip around at least one of the edges of the carbon brush that extend in the guide direction. As a result thereof the carbon brush can be guided in the carbon brush guide with an exceptionally small amount of play. The reduces the rate of wear of the carbon brush, and noise generation during operation of the electrodynamic machine can also be minimized. According to a preferred embodiment, in the case of a multilayer carbon brush the second shell section extends along a surface of the multilayer carbon brush that is embodied as a single layer. By this means a short-circuiting of different carbon bars of the multilayer carbon brush due to the metallic second shell section is avoided. Preferably the first shell section and the second shell section are formed with identical shapes. In this way the carbon brush can be guided uniformly in both shell sections, as a result of which even wearing of the carbon brush can be ensured. PCT/EP2006/067031 / 2005P01959WOCN 4/9 The carbon brush holder according to the invention is used in particular in electric motors for domestic appliances, such as, for example, in drive motors for washing machines or tumble dryers or in blower motors for vacuum cleaners. It is pointed out that the features of the dependent claims can be combined with one another in any way without departing from the inventive concept. Exemplary embodiments of the invention are explained in more detail below with reference to the drawing, in which: Fig. 1 shows a cross-section through a carbon brush holder transversely to the guide direction, Fig. 2a-2d show individual component parts of the carbon brush holder according to Figure 1, Fig. 3 shows a side view of the carbon brush holder according to Figure 1, Fig. 4a, 4b show a plan view onto the carbon brush holder according to Figure 1 from obliquely above and obliquely below, respectively. Before dealing with the drawings in greater depth let it be noted that corresponding or identical elements or individual parts of the carbon brush holder are designated by the same reference signs in all figures of the drawing. Fig. 1 shows a cross-section through a carbon brush holder 1 transversely to the guide direction F (see arrow in Figure 3). Individual component parts of the carbon brush holder 1 according to Figure 1 are shown in Figures 2a to 2d. The carbon brush holder 1 has a housing 2 (see also Figure 2a) which is embodied from plastic. Arranged in the housing 2 is a cartridge-type carbon brush guide 3 in which a carbon brush 4 is guided. The carbon brush 4 shown is a multilayer carbon brush which consists of a first carbon bar 5 and a second carbon bar 6 with an intermediate insulating layer 7 arranged therebetween. The carbon brush guide 3 is formed by means of a first shell section 8 and a second shell section 9. The first shell section 8 is integrally molded on the housing 2 and consists of electrically insulating plastic. The second shell section 9 (see also Figure 2b) is shaped from a sheet metal and is inserted into the housing 2. PCT/EP2006/067031 / 2005P01959WOCN 5/9 The first shell section 8 and the second shell section 9 are formed identically in a U shape, each having two arms 10, 11 and 12, 13 and a base 14 and 15 connecting the arms 10 and 11 and 12 and 13, respectively. A spring belly 16 or 17 for receiving a helical spring 18 is embodied in the first shell section 8 as well as in the second shell section 9 in each case in the central area of the base 14 and 15 respectively. The helical spring 18 causes the carbon brush 4 to be pressed in the guide direction F onto a commutator or collector ring of an electric motor (not shown), with the result that the carbon brush 4 can rest with its end face 19 in continuous areal contact on the commutator or collector ring. A flat guide area 20, 21 and 22, 23 follows in each case between the spring belly 16 and 17 and the associated arms 10, 11 and 12, 13, respectively, on both sides of the respective spring belly 16 and 17. Each of the flat guide areas 20, 21, 22 or 23 encompasses one of the edges K of the carbon brush 4 extending in the guide direction F in each case with the associated arm 10, 11, 12 or 13 adjoining it. The carbon brush 4 is in contact with the outer surfaces of the first carbon bar 5 at the arms 10, 11 and the flat guide areas 20, 21 of the first shell section 8 and with the outer surfaces of the second carbon bar 6 at the arms 12, 13 and the flat guide areas 22, 23 of the second shell section 9. In this way the carbon brush 4 is guided with its first carbon bar 5 through the first shell section 8 and with its second carbon bar 6 through the second shell section 9, thereby preventing leakage currents between the two carbon bars 5, 6 by way of the metallic second shell section 9. In order to ensure precise positioning of the metallic second shell section 9 the housing 2 has a receptacle 24 for retaining the second shell section 9, in particular its arm 12, in a form-fit manner. During assembly the second shell section 9 is inserted through an opening 25 of the carbon brush holder 1 into the receptacle 24 and snapped into place with the housing 2 by means of a latching element 26 (see Figure 2b). The opening 25 of the housing 2 can be closed by means of a cover plate 27 (see also Figure 2d). Preferably the cover plate 27 has integrally molded onto it latching elements 28, 29 by means of which the cover plate 27 can be snapped into place with the housing 2. A receptacle 30 is also embodied on the inside of the cover plate 27 for the purpose of retaining the second shell section 9, in particular its arm 13, in a form-fit manner, such that the second shell section 9 can be precisely positioned by closing the opening 25 with the cover plate 27. Also integrally molded on the cover plate 27 are positioning pins 31, 32 by means of which the carbon brush holder 1 of the electric motor (not shown) can be precisely positioned. Lugs 33, 34 are integrally molded on opposite sides of the housing 2 in order to secure the carbon brush holder 1 to the electric motor, each of said lugs 33, 34 having a mounting hole 35, 36 for passing through a retaining bolt or retaining pin (not shown). PCT/EP2006/067031 / 2005P01959WOCN 6/9 The housing 2 with the first shell section 8 as well as the cover plate 27 are manufactured from Duroplast, which is thermally stable up to temperatures of at least 250° C, by means of an injection molding method. The housing 2 as well as the cover plate 27 have channel- shaped recesses 37, 38 in the area of the insulating layer 7 in order to ensure that carbon dust caused by abrasion of the carbon brush 4 cannot accumulate between the carbon bars 5 and 6 and thereby cause leakage currents between the carbon bars 5 and 6. The carbon brush is electrically contacted by means of a plug-in connector part 39 which rests against the end of the helical spring 18 opposite the carbon brush 4. PCT/EP2006/067031 / 2005P01959WOCN 7/9 List of reference signs 1 Carbon brush holder 2 Housing 3 Carbon brush guide 4 Carbon brush 5 First carbon bar 6 Second carbon bar 7 Insulating layer 8 First shell section 9 Second shell section 10, 11 Arms of the first shell section 12,13 Arms of the second shell section 14 Base of the first shell section 15 Base of the second shell section 16 Spring belly of the first shell section 17 Spring belly of the second shell section 18 Helical spring 19 End face of the carbon brush 20, 21 Flat guide areas of the first shell section 22, 23 Flat guide areas of the second shell section 24 Receptacle for an arm of the second shell section 25 Opening of the carbon brush holder 26 Latching element of the second shell section 27 Cover plate 28, 29 Latching elements of the cover plate 30 Receptacle for an arm of the second shell section 31, 32 Positioning elements 33,34 Lugs 35, 36 Mounting holes 37, 38 Channel-shaped recesses 39 Plug-in connector part PCT/EP2006/067031 / 2005P01959WOCN 8/9 Claims 1. A carbon brush holder for an electrodynamic machine, in particular an electric motor, having a cartridge-type carbon brush guide (3) which is arranged in a housing (2) for the purpose of mounting a carbon brush (4) which can be displaced in a guide direction (F), the carbon brush guide (3) having separate guide elements in the form of a first shell section (8) and a second shell section (9), each of which extends along the guide direction (F), characterized in that the first shell section (8) is embodied from electrically insulating material and the second shell section (9) from metal. 2. The carbon brush holder as claimed in claim 1, characterized in that the first shell section (8) is embodied from plastic. 3. The carbon brush holder as claimed in claim 1 or 2, characterized in that the first shell section (8) is integrally molded on the housing (2) as a single piece. 4. The carbon brush holder as claimed in one of claims 1 to 3, characterized in that the second shell section (9) is shaped from a sheet metal. 5. The carbon brush holder as claimed in one of the preceding claims, characterized in that the second shell section (9) has at least one latching element (26) by means of which the second shell section (9) can be fixed in the housing (2). 6. The carbon brush holder as claimed in one of the preceding claims, characterized in that a receptacle (24) for retaining the second shell section (9) is embodied in the housing (2). 7. The carbon brush holder as claimed in one of the preceding claims, characterized in that the housing (2) has at least one opening (25) which extends in the guide direction (F) and which can be closed by means of a cover plate (27). 8. The carbon brush holder as claimed in claim 7, characterized in that the cover plate (27) has at least one latching element (28, 29) by means of which the cover plate (27) can be snapped into place with the housing (2). PCT/EP2006/067031 / 2005P01959WOCN 9/9 9. The carbon brush holder as claimed in claim 7 or 8, characterized in that a receptacle (30) for retaining the second shell section (9) is embodied on the cover plate (27), such that the second shell section (9) can be fixed in the housing (2) by means of the cover plate (27). 10. The carbon brush holder as claimed in one of claims 7 to 9, characterized in that positioning elements (31, 32) are integrally molded on the cover plate (27) for the purpose of positioning the carbon brush holder (1) on the electrodynamic machine. 11. The carbon brush holder as claimed in one of the preceding claims, characterized in that retaining elements (33, 34, 35, 36) are integrally molded on the housing (2) for the purpose of securing the carbon brush holder (1) to the electrodynamic machine. 12. The carbon brush holder as claimed in one of the preceding claims, characterized in that the second shell section (9) is arranged in the housing (2) opposite the first shell section (8). 13. The carbon brush holder as claimed in claim 12, characterized in that the first shell section (8) and the second shell section (9) are embodied for guiding opposite side surfaces of the carbon brush (4). 14. The carbon brush holder as claimed in one of the preceding claims, characterized in that the first shell section (8) and/or the second shell section (9) in each case grip around at least one of the edges of the carbon brush (4) extending in the guide direction (F). 15. The carbon brush holder as claimed in one of the preceding claims, characterized in that in the case of a multilayer carbon brush (4) the second shell section (9) extends along a surface (6) of the multilayer carbon brush (4) that is embodied as a single layer. 16. The carbon brush holder as claimed in one of the preceding claims, characterized in that the first shell section (8) and the second shell section (9) are formed with identical shapes. 17. An electric motor for a domestic appliance having at least one carbon brush holder (1) as claimed in one of claims 1 to 16. Carbon brush holder for an electrodynamic machine. The invention relates to a carbon brush holder for an electrodynamic machine, in particular an electric motor, having a carbon brush guide (3) which is in the form of a cartridge and is arranged in a housing (2), for mounting a carbon brush (4) which can be displaced in a guide direction (F), the carbon brush guide (3) having separate guide elements in the form of a first shell element (8) and a second shell element (9), which each extend along the guide direction (F), and to an electric motor for a domestic appliance having such a carbon brush holder (1). The first shell element (8) is formed from an electrically insulating material, and the second shell element (9) is formed from metal. |
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| Patent Number | 268402 | |||||||||||||||
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| Indian Patent Application Number | 1233/KOLNP/2008 | |||||||||||||||
| PG Journal Number | 36/2015 | |||||||||||||||
| Publication Date | 04-Sep-2015 | |||||||||||||||
| Grant Date | 28-Aug-2015 | |||||||||||||||
| Date of Filing | 26-Mar-2008 | |||||||||||||||
| Name of Patentee | BSH BOSCH UND SIEMENS HAUSGERATE GMBH | |||||||||||||||
| Applicant Address | CARL-WERY-STR. 34, 81739 MUNCHEN | |||||||||||||||
Inventors:
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| PCT International Classification Number | H01R 39/24 | |||||||||||||||
| PCT International Application Number | PCT/EP2006/067031 | |||||||||||||||
| PCT International Filing date | 2006-10-04 | |||||||||||||||
PCT Conventions:
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