Brush assembly for a motor and motor

Abstract

Brush assembly (1), in particular hammer brush assembly (1), for a mechanically commutated electric motor, comprising at least one base body (3) with at least one mounting boss (8), wherein at least one spring (11) is arranged on the mounting boss (8), wherein at least one bolt (5) is attached to the mounting boss (8), wherein at least one brush (4) is rotatably mounted on the bolt (5), and wherein a force in at least one direction of rotation can be exerted on the brush (4) by means of the spring (11), wherein coils (12) of the spring (11) are arranged at least partially surrounding the mounting boss (8) between the base body (3) and a contact surface (19) that is rotationally fixed relative to the mounting boss (8), characterized in that at least one washer (14) is arranged between an end wall (13) of the mounting boss (8) and the brush (4), and that the contact surface (19) is formed on the washer (14).and that the bolt (5) has at least one bolt shoulder (16).

Description

[0001] The invention relates to a brush assembly, in particular a hammer brush assembly for a motor, especially a mechanically commutated electric motor. The brush assembly has at least one base body with at least one mounting boss. At least one spring is arranged on the mounting boss, and at least one bolt is attached to the mounting boss. At least one brush is rotatably mounted on the bolt, and the spring is capable of exerting a force on the brush in at least one direction of rotation.

[0002] Brush assemblies in the form of hammer brush assemblies are used particularly in electric motors with copper-graphite commutation. A known hammer brush assembly features a cover that supports the brush assembly. Two hammer brushes are each mounted on a bolt. Each hammer brush is pressed against a commutator by a torsion spring. The torsion spring is threaded onto a boss that is integrally connected to the cover. One end of the torsion spring is supported in the cover, while the other end rests against the hammer brush or, in an alternative version, is provided with a hook into which the hammer brush is suspended. A washer is positioned between the hammer brush and the boss.

[0003] A disadvantage of this design is a force resulting from the twisting of the torsion spring when under tension. This force presses on the washer and the brush, potentially causing the brush to tilt. This tilting negatively affects the contact surface of the hammer brush on the commutator. However, a uniform contact surface is essential for good current transfer between the brush and the commutator. Furthermore, the friction on the bolt caused by the brush tilting reduces the brush's smooth operation, increasing the risk of brush jamming.

[0004] From EP 1 808 942 A2, a hammer brush device is known which is advantageous compared to the hammer brush device described above, particularly with regard to the brush contact force. The hammer brush device disclosed in this publication comprises at least one bolt on which a brush is rotatably mounted and is subject in the direction of rotation to a force exerted by at least one spring, the coils of which surround the bolt, wherein the coil of the spring adjacent to the brush is supported on a support element rotatably mounted on the bolt, which rotates with the brush, and wherein the coils of the spring surround a dome formed integrally with a cover or a projection formed as part of the bolt.

[0005] EP 2 600 503 A1 describes a brush assembly for an electric motor with at least one lever brush rotatably mounted on a bolt. This brush assembly also includes a spring whose coils surround the bolt and engage on the outer surface of the lever brush. The bolt rotates in the same way as the lever brush. To dampen vibrations caused by this movement, the bolt is mounted in a damping sleeve.

[0006] Based on the aforementioned prior art, the invention is based on the objective of providing a brush device, in particular a hammer brush device, and a motor, which are designed in such a way that at least a largely uniform contact of the brush on the commutator is achieved.

[0007] The aforementioned problem is solved in a brush assembly of the generic type according to the characterizing part of claim 1. The coils of the spring are arranged at least partially surrounding the mounting boss between the base body and a contact surface that is rotationally fixed relative to the mounting boss. At least a portion of the coils of the spring surrounds the circumference of the mounting boss in an axial direction. The axial direction of the mounting boss is, in particular, parallel to the axis of rotation of the brush. The coils of the spring are thus supported in the axial direction between the base body and a contact surface that is rotationally fixed relative to the mounting boss. The contact surface is rotationally fixed relative to the mounting boss, so that advantageously no relative movement, in particular in a rotational direction, can occur between the contact surface and the mounting boss. The contact surface is, in particular, rotationally fixed relative to the circumference of the mounting boss.The bolt is, for example, pressed or screwed into the mounting boss.

[0008] The contact surface advantageously extends radially outwards relative to the circumferential surface of the mounting boss. In particular, the contact surface has a larger outer diameter than the circumferential surface of the mounting boss. For example, the contact surface extends orthogonally to an axis of rotation of the brush or orthogonally to a longitudinal axis of the mounting boss.

[0009] Preferably, the contact surface is formed directly at a free end of the mounting boss, i.e., at the end facing away from the base body. However, it is also possible for the stop surface to be arranged at a distance from the free end of the mounting boss. In this case, at least some of the spring coils surround not only the mounting boss but also at least the component(s) located between the mounting boss and the contact surface.

[0010] The term "brush" refers to a sliding contact suitable for interacting with the armature of a commutator. Preferably, the brush assembly is a hammer brush assembly with hammer brushes.

[0011] The base body is preferably designed as a brush cover, motor cover, or end cap of a motor. For example, the base body may be constructed in one piece or in multiple parts.

[0012] The invention offers an advantage over the prior art in that the rotationally fixed contact surface prevents a one-sided force emanating from the spring coils from acting axially on the brush. This prevents axial tilting of the brush, thereby ensuring smooth rotation of the brush and uniform contact of the brush with the commutator.

[0013] According to a first embodiment of the brush assembly, it is particularly provided that the mounting boss is formed integrally with the base body. For example, the base body and the mounting boss are manufactured integrally from a plastic. The plastic is advantageously electrically insulating and dimensionally rigid. In particular, it is provided that the contact surface is formed integrally with the mounting boss. In this further development, for example, a spring must be spread open in order to be applied to the mounting boss.

[0014] According to an alternative embodiment, the mounting boss is a separate component attached to the base body. The mounting boss is connected to the base body, for example, by force-fit, form-fit, and / or material-fit connection. Preferably, the mounting boss is pressed or screwed into the base body. In particular, the contact surface is formed integrally with the base body, and the mounting boss is attached to the base body by means of the already applied spring.

[0015] For example, the mounting boss is provided for on the rear side of the base body. Preferably, the mounting boss protrudes from the rear side of the base body. Advantageously, this is the rear side of a brush cover.

[0016] According to the invention, at least one washer is arranged between an end wall of the mounting boss and the brush. The contact surface is formed on the washer. The side of the washer facing the end wall forms the contact surface. The washer is held non-rotatably against the mounting boss. Preferably, the washer rests directly against the end wall.

[0017] The bolt on which the spring is rotatably mounted is designed to have at least one bolt shoulder. The washer is preferably fixed between the end face of the mounting boss and the bolt shoulder. The force between the end face and the bolt shoulder is selected such that the washer is held rotationally fixed. In particular, the bolt shoulder is positioned in contact with the washer, advantageously on the side of the washer opposite the contact surface. This secures the washer between the end face of the mounting boss and the bolt shoulder.

[0018] In this embodiment, the advantage described above arises from the fact that the washer cannot be tilted in the axial direction by a force exerted by the spring, so that the brush always has an advantageous contact surface with the commutator.

[0019] According to a further embodiment of the brush assembly, the bolt has a first bolt section for insertion into a bolt opening formed in the mounting boss and a second bolt section for supporting the brush. The second bolt section has a shoulder compared to the first bolt section. The first bolt section is secured in the bolt opening, for example, by being pressed or screwed into the bolt opening on the mounting boss.

[0020] Preferably, the bolt shoulder is formed by the second bolt section projecting radially beyond the first bolt section. In particular, it is provided that the diameter of the second bolt section is larger than the diameter of the first bolt section, thereby forming the bolt shoulder in the form of a radially circumferential annular surface.

[0021] According to an advantageous embodiment, the brush, which is rotatably mounted on the bolt, is secured axially, i.e., in a direction parallel to the axis of rotation of the brush, by means of a bolt head arranged on the bolt. The bolt head is, for example, formed integrally with the bolt or attached to the bolt.

[0022] Preferably, according to a further embodiment, the bolt projects axially beyond the brush, allowing axial play between the bolt head and the brush. The axial play of the brush mounted on the bolt is thus determined by the length of the bolt, in particular by the length of the second bolt section. It is also provided that at least one washer is arranged between the bolt head and the brush.

[0023] This advantageously simplifies the assembly process, as no complex adjustment of the axial play between the bolt head and the brush or between the bolt head and the upper washer is required. During assembly, the bolt can, for example, be positioned against the washer on the mounting dome side. The axial play is then automatically determined based on the length of the second bolt section.

[0024] Another embodiment of the brush assembly provides that at least one coil end of the spring, which forces the brush in a rotational direction during assembly, engages the brush. Specifically, the coil end of the spring rests against the brush or is hooked into the brush. The spring loads the brush in such a way that it is forced in the direction of rotation and, particularly during assembly, against a commutator of a motor. To prevent the spring from rotating on the mounting boss, a second coil end of the spring is fixed, for example, to the base body or the mounting boss. The spring is preferably a torsion spring.

[0025] According to a preferred embodiment, the brush assembly has at least two mounting bosses arranged on the base body. At least one spring is arranged on each mounting boss, bearing axially between a contact surface and the base body. At least one brush is rotatably mounted on each mounting boss. The details of the design of each mounting boss are described in the exemplary embodiments of a single mounting boss.

[0026] The aforementioned problem is further solved by a motor, in particular a mechanically commutated electric motor with at least one rotor, at least one stator, at least one motor shaft, and at least one commutator, in that the motor has at least one brush assembly according to one of the described embodiments. Particularly preferably, the brush assembly has two brush domes, which correspond to a brush dome with a brush mounted thereon according to one of the exemplary embodiments described for a brush dome. Preferably, the motor has a housing, and the base body of the brush assembly forms the motor cover.

[0027] According to a first embodiment of the motor, at least one winding end of the spring engages the brush, so that the brush is subjected to a rotational load and thereby pressed against the commutator. The spring is supported axially between the base body and the contact surface, so that the brush is not subjected to an axial load caused by the windings of the spring.

[0028] Further advantageous embodiments of the invention will become apparent from the following description of the figures and the dependent claims. These show: Fig. 1 An embodiment of a brush assembly seen from the rear of the brush cover, Fig. 2 the brush assembly according to Fig. 1 in cutaway view (AA) according to Fig. 1, Fig. 3 the exemplary embodiment of the Fig. 2 in a detailed view, and Fig. 4 the brush assembly according to Fig. 1 with only one brush and without a commutator in perspective view.

[0029] In the various figures of the drawing, identical parts are always labelled with the same reference symbols.

[0030] The following description claims that the invention is not limited to the exemplary embodiments and not to all or several features of the described combinations of features; rather, each individual partial feature of the exemplary embodiment(s) is also significant for the subject matter of the invention, independent of all other partial features described in connection therewith, both on its own and in combination with any features of another exemplary embodiment.

[0031] Fig. Figure 1 shows an embodiment of a brush device 1 in a rear view with an exemplary commutator 2 of a motor (not shown).

[0032] Fig. Figure 2 shows the brush assembly 1 according to Fig. 1 in section view along the section line AA in Fig. 1. Fig. Figure 3 shows a detailed representation of the Fig. 2. The brush assembly 1 has according to Fig. 2 and Fig. 3 a base body 3 in the form of the brush cover. Two brushes 4 in the form of hammer brushes are arranged on the base body 3, each of which is pivotably mounted on a bolt 5. In Fig. 2 and Fig. Figure 3 shows only one of the bolts 5. The base body 3 also has a bolt opening 6 passing through the base body 3 for receiving or mounting the bolt 5.

[0033] The bolt opening 6 is at least partially provided in a mounting boss 8 located on the rear side 7 of the base body 3, which is formed integrally with the base body 3. Corresponding to the number of bolts 5, a corresponding number of mounting bosses 8 – here two – are distributed around the circumference of the base body 3. The description below is representative of all mounting bosses 8, specifically one mounting boss 8 with a spring 11 attached to it. Each mounting boss 8 is surrounded by an annular wall 9 at a distance. This creates an annular space 10 between the mounting boss 8 and the annular wall 9.

[0034] A spring 11, here in the form of a torsion spring, is arranged in the annular space 10, such that the spring 11 surrounds the mounting boss 8 and its coils 12 engage at least partially in the annular space 10. On its side facing away from the base body 3 and towards the brush 4, the spring 11 has a hook-shaped coil end 12a projecting outwards towards the brush 4. The coil end 12a serves to drive or pre-tension the brush 3 against the commutator 2 shown in the example.

[0035] A first washer 14 rests against an end wall 13 of the mounting boss 8. A first side 14a of the washer rests against the end wall 13 of the mounting boss 8, and a second side 14b of the washer points away from the mounting boss 8. The diameter of the washer 14 is preferably larger than that of the mounting boss 8, so that the contact surface 19 is formed on the first side 14a of the washer. The coils 12 of the spring 11 surround the mounting boss 8 and rest axially against the base body 3 and the contact surface 19, bearing against them. For illustrative purposes only, the coils 12 are shown spaced apart from the base body 3 and the contact surface 19 in the figures.

[0036] As explained above, the base body 3, or the mounting boss 8, has the bolt opening 6 for mounting the bolt 5. The bolt 5 has a first bolt section 5a for insertion into the bolt opening 6 and a second bolt section 5b with a bolt head 15 for mounting the brush 4. The diameter of the bolt 5 in the second bolt section 5b is larger than the diameter of the bolt 5 in the first bolt section 5a, so that the bolt 5 has a radially circumferential bolt shoulder 16 at the boundary or transition from the first bolt section 5a to the second bolt section 5b. Preferably, the bolt 5 is pressed into the bolt opening 6 with its first bolt section 5a. For this purpose, the first bolt section 5a preferably has a fastening element, e.g., a knurled collar 17.

[0037] In the assembled state of the brush assembly 1, the bolt 5 is fastened with the first bolt end 5a in the bolt opening 6, the bolt 5 passing through the washer 14 abutting the mounting boss 8 and bearing with its bolt shoulder 16 against the second washer side 14b (see Fig. 3) This holds the washer 14 down on the dome 8 or fixes it in a rotationally fixed manner and advantageously prevents it from tilting when the spring 11 twists and presses against the contact surface 19 or onto the washer 14.

[0038] The brush 4 is rotatably mounted on the second bolt section 5b. The brush 4 can be slid onto the second bolt section 5b before assembly. In the assembled state, the bolt 5 projects beyond the brush 4, so that there is a small gap or axial play between the bolt head 15 and the brush 4. The bolt head 15 secures the brush 4 to the bolt 5. Preferably, a second washer 18 is provided between the bolt head 15 and the brush 4.

[0039] As explained, the winding end 12a of the spring 11 rests on the outside of the brush 4 or is hooked into the brush 4, so that the brush 4 is loaded in a direction of rotation and pressed against the commutator 2.

[0040] Fig. Figure 4 illustrates in perspective view how the brush 4 sits on the bolt 5 as described above and, driven by the spring 11, is rotated towards the commutator 2 (not shown here) by means of the hook-shaped winding end 12a that engages the brush 4. For the sake of clarity, in Fig. 4 only one brush 4 is shown on one of the two mounting domes 8.

[0041] In the brush assembly 1 according to the invention, it is advantageous that, due to the bolt shoulder 16, the washer 14 is held down against the end wall 13 of the mounting boss 8. This prevents the washer 14 from tilting, even when the spring 11 twists, due to a force acting upon it, particularly from the coils 12 of the spring 11. This ensures that the brush 4 bears evenly against the commutator 2, thus guaranteeing good current transfer between the brush 4(s) and the commutator 2. Furthermore, it prevents one-sided force from pressing on the brush 4, which in turn ensures smooth operation of the brush 4.

[0042] Another advantage of the offset bolt 5 is a simplified assembly process, which eliminates the need for complex adjustment of the axial play between the bolt 5 and the second washer 18 or the brush 4. During assembly, the bolt 5 can simply be placed flush against the first washer 14.

[0043] The invention is not limited to the embodiments illustrated and described, but also encompasses all embodiments that have the same effect within the meaning of the invention. It is expressly emphasized that the embodiments are not limited to all features in combination; rather, each individual feature can have inventive significance independently of all other features. Furthermore, the invention is not yet limited to the combination of features defined in claim 1, but can also be defined by any other combination of specific features from all disclosed individual features. This means that, in principle, virtually any individual feature of claim 1 can be omitted or replaced by at least one individual feature disclosed elsewhere in the application. Reference sign 1 Brush assembly 2 Commutator 3 basic shapes 4 brushes 5 bolts 5a first bolt end 5b second bolt end 6 bolt opening 7 Back 8 Mounting dome 9 Ring wall 10 annular space 11 spring 12 turns 12a Hook-shaped coil end 13 Front wall of 8 14 first washer 14a first washer side 14b second washer side 15 bolt head 16 bolt heel 17 Riffelbund 18 second washer 19 Plant area

Claims

[1] Brush assembly (1), in particular hammer brush assembly (1), for a mechanically commutated electric motor, comprising at least one base body (3) with at least one mounting boss (8), wherein at least one spring (11) is arranged on the mounting boss (8), wherein at least one bolt (5) is attached to the mounting boss (8), wherein at least one brush (4) is rotatably mounted on the bolt (5), and wherein a force in at least one direction of rotation can be exerted on the brush (4) by means of the spring (11), wherein coils (12) of the spring (11) are arranged at least partially surrounding the mounting boss (8) between the base body (3) and a contact surface (19) that is rotationally fixed relative to the mounting boss (8), characterized by, that at least one washer (14) is arranged between an end wall (13) of the mounting dome (8) and the brush (4), that the contact surface (19) is formed on the washer (14), and that the bolt (5) has at least one bolt shoulder (16). [2] Brush assembly (1) according to claim 1, characterized by , that the mounting dome (8) is formed integrally with the base body (3), in particular that the mounting dome (8) is arranged on a rear side (7) of the base body (3), or that the mounting dome (8) is attached to the base body (3). [3] Brush assembly (1) according to claim 1 or 2, characterized by , that the bolt shoulder (16) is arranged in a position adjacent to the washer (14), and that the washer (14) is fixed between the end wall (13) of the mounting boss (8) and the bolt shoulder (16). [4] Brush assembly (1) according to claim 3, characterized by, that the bolt (5) has a first bolt area (5a) for insertion into a bolt opening (6) formed in the mounting boss (8) and a second bolt area (5b) for bearing the brush (4), and that the second bolt area (5b) has a bolt shoulder (16) opposite the first bolt area (5a), in particular that the second bolt area (5b) projects radially beyond the first bolt area (5a) so that the bolt shoulder (16) is formed. [5] Brush assembly (1) according to claim 4, characterized by , that the diameter of the second bolt section (5b) is larger than the diameter of the first bolt section (5a), so that the bolt shoulder (16) is formed in the form of a radially circumferential ring surface. [6] Brush assembly (1) according to any one of the preceding claims, characterized by , that the brush (4) mounted on the bolt (5) is secured by means of a bolt head (15) arranged on the bolt (5). [7] Brush assembly (1) according to claim 6, characterized by , that the bolt (5) protrudes in axial direction beyond the brush (4), so that there is axial play between the bolt head (15) and the brush (4). [8] Brush assembly (1) according to claim 6 or 7, characterized by , that at least one washer (18) is arranged between the bolt head (15) and the brush (4). [9] Brush assembly (1) according to any one of the preceding claims, characterized by , that a winding end (12a) of the spring (11) engages the brush (4), in particular rests against the brush (4) or is hooked into the brush (4), so that the brush (4) is subjected to a rotational load. [10] Brush assembly (1) according to any one of the preceding claims, characterized by, that at least two mounting bosses (8) are arranged on the base body (3), that at least one spring (11) is arranged on each mounting boss (8), that the spring (11) extends between the base body (3) and the contact surface (19), and that a brush (4) is rotatably mounted on each mounting boss (8). [11] Motor, in particular a mechanically commutated electric motor, comprising at least one rotor, at least one stator, at least one motor shaft and at least one commutator (2), characterized by at least one brush device (1) according to any one of claims 1 to 10. [12] Motor according to claim 11, characterized by , that at least one winding end (12a) of the spring (11) engages the brush (4) so ​​that the brush (4) is subjected to a rotational load and pressed against the commutator (2).

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