EP2198490B1 - Brush arrangement and electric machine, in particular electric domestic appliance - Google Patents

Description

Background of the invention

The invention relates to a brush assembly on an electrical machine, in particular on an electrical domestic appliance, with a brush holder receiving the brush sleeve, which can be fixed in a position of use on the housing of the machine, and an electric machine equipped therewith.

State of the art

A brush arrangement of the type mentioned is from the German patent application DE 197 17 594 A1 known.

The relevant machine has a pot-like housing made of an electrically conductive material, in which the commutator is rotatably mounted. In the region of the end face of the housing holding means are formed, which serve to hold the carbon brushes receiving brush sleeves. The carbon brushes are slidably mounted in the brush sleeves and biased by a helical compression spring in the direction of the commutator. Since the brush sleeves are also electrically conductive, they must each be rigidly attached to a support member made of an electrically insulating material, in particular made of plastic, are attached. Each support member is inserted during assembly from the outside radially inwardly in the direction of the commutator in the holding means until the brush sleeves occupy their position of use. In this case, the contact spring of the stator comes into contact with the radial surface of the respective brush sleeve. In this position locking and stop means secure the support member and thus the associated brush sleeve in all directions. A later replacement of support member and brush sleeve is basically by a mechanical lifting of the locking connection and a radially outward displacement possible. In rare exceptional cases, however, an unintentional loosening of the latching connection may occur, especially if in a fault, the temperatures in the electrical machine unusually high and the material of the support member loses strength.

The problem underlying the invention

The object of the invention is to further improve the safety of such an electric machine even in the event of a fault.

Inventive solution

This object is achieved by a brush arrangement of the generic type in that the brush arrangement has catch means by means of which the brush sleeve can be locked in a securing position when leaving the use position.

By means of the invention, it can be advantageously avoided that the brush sleeve shifts beyond the securing position if it is released in the event of a fault. In this way, it can be ensured with the invention that the prescribed electrical safety distances are maintained even in the event of a fault, in particular with regard to the brushes and the brush sleeves.

Preferred embodiment of the invention

Advantageous embodiments and developments, which can be used individually or in combination with each other, are the subject of the dependent claims.

According to a preferred embodiment of the invention, the catching means comprise at least one latching device which engages the brush sleeve latching in the securing position. With such a locking device can be implemented in a particularly simple and inexpensive way, the catch of the invention. This particularly ensures that Catching the brush sleeve against another directed away from the commutator displacement, especially in the direction of other electrically conductive components of the machine. This makes it possible to ensure that safety distances between the brush arrangement and other conductive components surrounding the brush arrangement are maintained even in the event of a fault. This embodiment of the invention may be particularly advantageous when the brush sleeve is equipped for biasing the brush with a compression spring or other suitable means which favors in the case of a release of the brush sleeve displacing this away from the commutator.

The latching device in this case advantageously has at least one recess provided on the radial surface of the brush sleeve into which engages a latching lug in the position of use against the radial surface upon reaching the securing position and counteracts a further displacement by form-locking. With this design, the invention can be realized in terms of manufacturing technology particularly simple and substantially weight and cost neutral with respect to the brush sleeve.

The recess can be formed, for example, circular or rectangular, in particular square. Such contours can be produced by drilling or, in particular, punching the recess without problems and within the framework of manufacturing steps which are required in any case, and by using tools and devices already used in the production process.

The invention is particularly applicable to a brush assembly in which the brush sleeve is formed electrically conductive and is therefore particularly secure against unwanted contact with other electrically conductive components.

The locking lug which is suitable for engagement in the recess when the securing position is reached is preferably formed by the contact spring of the stator, which has sufficient strength to secure the brush sleeve. In addition, the formation of the catch in this case requires no additional or modified components with respect to the cited prior art with the exception of the adapted brush sleeve and is therefore also essentially cost and weight neutral. In addition, in an exchange of the brush sleeves basically a retrofitting of existing electrical devices with catching means according to the invention, for example, in the context of an already due wear replacement, possible.

The recesses in the radial surface of the brush sleeves are preferably arranged in the position of use in the radial direction between the commutator and the stator of the electric machine and shift in an unwanted release in the direction of the contact springs. By this design, the most common misalignment of the brush sleeve is counteracted in case of machine failure.

The contact springs of the stator are in the position of use of the brush sleeve with advantage in the direction of the commutator inclined to the contact surface of the brush sleeve. When overlapping with the associated recess, the relevant contact spring engages in the recess and is deformed in a further, radially acting away from the use position on the brush sleeve force in the direction of a blocking contour. As a result, the interference-related and unwanted displacement of the brush sleeve in the direction of an electrical contact with other electrically conductive components is particularly reliably avoided. However, a renewed insertion of the brush sleeve to remedy the disorder is still possible without significantly increased effort.

The invention can also be used with particular advantage in a brush arrangement in which the housing of the relevant machine is designed to be electrically conductive. Especially with such electrical devices, contact between the brush sleeve and the housing is reliably avoided. The brush sleeve is preferably attached at a deratigen training on an electrically insulating support member, which in turn can be used in holding means provided on the housing, in particular insertable, is.

The support member is inserted in the course of assembly preferably in the direction of the commutator in the holding means of the housing, ie in the direction of a common mounting direction of the brush sleeve. The specialist staff involved in the replacement of the brush sleeve thus does not need any of the usual in terms of assembly in this case Practice divergent teaching to be taught.

According to another preferred embodiment of the invention, the catching means of the brush arrangement have a projecting from the brush sleeve projection which abuts in the securing position to a securing element, in particular to the contact spring. Such a projection can be produced for example with little manufacturing effort by local plastic deformation of the sleeve wall and is also substantially both weight and cost neutral.

Suitable means for fixing the brush sleeve in the position of use on the housing of the machine are known from the German patent application DE 19717594 A1 the entire content of which is incorporated herein by reference.

Brief description of the drawings

The invention is explained in more detail below with reference to schematic drawings of two exemplary embodiments with further details.

Fig. 1:

eine Aufsicht auf das Gehäuse einer elektrischen Maschine mit einer erfindungsgemäß ausgebildeten Bürstenanordnung;

Fig. 2:

einen Schnitt I-I durch das in Fig. 1 dargestellte Gehäuse mit in Gebrauchsstellung befindlicher Bürstenhülse;

Fig. 3:

den Schnitt I-I mit in Sicherungsstellung befindlicher Bürstenhülse;

Fig. 4:

eine perspektivische Ansicht der Baugruppe aus Bürstenhülse, Kohlebürste und Tragteil;

Fig. 5:

eine perspektivische Ansicht dieser Baugruppe nach dem Einsetzen in das Gehäuse in Gebrauchsstellung;

Fig. 6:

die zuvor genannte, perspektivisch gezeigte Baugruppe in Sicherungsstellung;

Fig. 7:

eine Bürstenanordnung nach einer anderen Ausführung der Erfindung.

Show it:

Fig. 1:

a plan view of the housing of an electrical machine with an inventively designed brush assembly;

Fig. 2:

a section II through the in Fig. 1 shown housing with befindlicher in use position brush sleeve;

3:

the section II with befindlicher in securing position brush sleeve;

4:

a perspective view of the assembly of brush sleeve, carbon brush and support member;

Fig. 5:

a perspective view of this assembly after insertion into the housing in the use position;

Fig. 6:

the aforementioned, shown in perspective fuse assembly;

Fig. 7:

a brush assembly according to another embodiment of the invention.

Detailed description based on an embodiment

In the FIG. 1 shown electric machine 1 has a pot-like housing 2, which receives on its end face 3 two similar brush assemblies 4. The brush assemblies 4 are arranged in mirror image with respect to a plane intersecting the axis of rotation 5 of the rotor. In the figures, only a brush assembly 4 is shown in the drawing for simplicity and finds its correspondence on the opposite side of the housing 2, not shown.

The structural design of the brush assembly 4 is made FIG. 2 in detail visible.

The brush assembly 4 consists of a brush sleeve 6, in which a carbon brush 7 is arranged displaceably in the direction of the arrow A. The carbon brush 7 is biased by a helical compression spring 8 in the direction of the commutator 9 connected to the rotor 5, wherein the carbon brush 7 applied end of the compression spring 8 is supported on the rear wall 10 of the brush sleeve 6. In a due to friction on the commutator 9 wear of the carbon brush 7, this is displaced by the compression spring 8 in the direction of the commutator 9, whereby the abrasion is compensated until reaching a wear limit.

The brush sleeve 6 and the housing 2 are each made of a sheet-like, electrically conductive material, for example, brass or steel sheet. These materials have a high strength, but can be easily processed by pressing, stamping or drilling to form complex parts.

The brush sleeve 6 is undetachably connected via an angle-like projecting leg 11 and a form-fitting manner with a plate-like support member 12 which consists of an electrically non-conductive material and the brush sleeve 6 with respect to the housing 2 electrically insulated. The support member 12 in turn is inserted during assembly together with the brush sleeve 6 in the direction of arrow B in the housing 2 integrally formed, tab-like holding means 13 until a protruding from the support member 12 stop 14 abuts the housing 2. The holding means are in FIG. 1 also shown in supervision.

In the now occupied position of use (illustration in FIG. 2 ) engage the support member 12 molded detents 15 in recesses 16 in the end face 3 and secure the assembly of brush sleeve 6 and support member 12 during normal operation against accidental displacement against the direction of arrow B. With regard to a possible structural design of a suitable device for Determination of this unit is again on the publication DE 197 17 594 A1 , in particular to the local description of the embodiment shown in the drawings, referenced.

At the radial part 17 facing away from the support part 12, the contact spring 18 of the stator 19 is elastically resilient. The contact spring 18 has a relative to the radial surface 17 in the direction of the commutator 9 inclined abutment region 20 which bears against the radial surface 17 under prestress. The contact spring 18 is a component to be provided anyway on the electric machine, which in principle can be designed basically unchanged with regard to its shape compared with suitable previously known solutions. In this case, a non-inventively equipped at first installation electrical device can be subsequently provided, for example, in the context of a maintenance operation, with the present invention corresponding catch.

In the brush sleeve 6 is further provided between its the commutator 9 facing the end and the contact spring 18 in the embodiment a circular recess 21, which in trouble-free operation of the electric machine 1 (as well as FIG. 5 apparent) is without function. The recess 21 may also have a deviating from the circular contour, which, for example, of a preferred Manufacturing process for the brush sleeve 6 or the shape of the contact spring 18 is affected.

At one in the Figures 3 and 6 On the other hand, under certain circumstances, a malfunction may unintentionally cause a shift in the accident Fig. 4 separately shown assembly of brush sleeve 6 and support member 12 in the direction of the arrow C, ie opposite to the mounting direction, carried out, which is favored by the bias of the compression spring 8. In a very far-reaching displacement of the brush sleeve 6 there is a risk that this comes into electrical contact with other electrically conductive components of the electric machine. Before such an unwanted electrical connection occurs, however, the contact area 20 of the contact spring 18 overlaps with the recess 21 and falls, as the contact spring 18 is under tension, latching into the recess 21 a. In this securing position, a further displacement of the assembly of brush sleeve 6 and support member 12 in the direction of the arrow C and thus prevents an electrical short circuit. However, the fault is in principle by renewed insertion of the assembly of brush sleeve and support member in the direction of arrow B, ie to the commutator 9 back, recoverable.

According to the embodiment FIG. 7 consist of the catching means for securing the brush sleeve 6 in its securing position of a protruding from the radial surface 17 of the brush sleeve 6 away from the carbon brush 7 projection 22, which by its ramp-like mounting (arrow B) of the assembly of brush sleeve 6 and support member 12 only slightly impaired, whose displacement in the direction of arrow C, however, sets after reaching the securing position, a considerable resistance. In this case too, basically all components known from the prior art, with the exception of the brush sleeve 6, can be used unchanged, wherein the brush sleeve 6 itself can be produced within the scope of conventional production with the features required for carrying out the invention essentially without additional costs or weight increase is. Likewise, also in the embodiment after FIG. 7 a retrofitting of existing electrical machines with catching invention possible.

The features disclosed in the foregoing description, the claims and the drawings may be of importance both individually and in any combination for the realization of the invention in its various forms.

Claims (13)

1. Brush arrangement (4) at an electrical machine (1), particularly at an electrical domestic appliance, with a brush sleeve (6), which receives the carbon brush (7) and which is fixable in a use setting at the housing (2) of the machine, characterised in that the brush arrangement (4) has catch means by way of which the brush sleeve (6) on leaving the use setting is lockable in a securing setting.
2. Brush arrangement according to claim 1, characterised in that the catch means comprise at least one detent device which grips the brush sleeve (6) in the securing setting by detenting.
3. Brush arrangement according to claim 2, characterised in that the detent device comprises at least one recess (21), which is provided at the radial surface (17) of the brush sleeve (6) and in which a detent lug, which in use setting bears against the radial surface, detents on reaching the safety setting.
4. Brush arrangement according to claim 3, characterised in that the recess (21) is formed to be round or rectangular, particularly square.
5. Brush arrangement according to any one of claims 1 to 4, characterised in that the brush sleeve (6) is constructed to be electrically conductive.
6. Brush arrangement according to claim 5, characterised in that the detent lug is formed by the contact spring (18) of the stator (19).
7. Brush arrangement according to claim 6, characterised in that the recess (21) in use setting is arranged in radial direction between commutator (9) and stator (19) of the electrical machine.
8. Brush arrangement according to claim 7, characterised in that the contact spring (18) in use setting of the brush sleeve (6) bears, with an inclination in the direction of the commutator (9), against the radial surface (17) of the brush sleeve.
9. Brush arrangement according to any one of the preceding claims, characterised in that the housing (3) of the machine (1) is constructed to be electrically conductive.
10. Brush arrangement according to claim 9, characterised in that the brush sleeve (6) is fastened to an electrically insulating support part (12), which in turn is insertable, particularly pushable, into retaining means (13) provided at the housing (2).
11. Brush arrangement according to claim 10, characterised in that the support part (12) is pushable into the retaining means (13) of the housing (2) in the direction of the commutator (9).
12. Brush arrangement according to claim 1, characterised in that the catch means comprise a projection (22) at the brush sleeve (6), which in the securing setting hits against a securing element, particularly against the contact spring (18).
13. Electrical machine (1), particularly electrical domestic appliance, with a brush arrangement (4) according to any one of the preceding claims.

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