WO2011009823A2

WO2011009823A2 - Electric motor having commutator-side bearing

Info

Publication number: WO2011009823A2
Application number: PCT/EP2010/060348
Authority: WO
Inventors: Steffen Huemmer; Dieter Spaeth
Original assignee: Robert Bosch Gmbh
Priority date: 2009-07-21
Filing date: 2010-07-16
Publication date: 2011-01-27
Also published as: CN102549889A; DE102009027859A1; EP2457310A2; WO2011009823A3; CN102549889B; DE102009027859B4

Abstract

The invention relates to an electric motor, particularly a starter for an internal combustion engine, having a stator (29) and a rotor (21) comprising a rotor shaft (2) and an armature (3) having a commutator (4), and having a bearing (25) on the commutator side. In order to provide the service life of the motor, the rotor shaft is rotationally supported by means of a thrust bearing.

Description

description

title

Electric machine with commutator-side bearing state of the art

The invention relates to an electric machine, in particular a starter for an internal combustion engine of a motor vehicle, which interacts with a Einspurvorrichtung, comprising a stator and a rotor, which comprises a rotor shaft and an armature with a commutator, and with a bearing on the commutator side.

It is known to form a starter for an internal combustion engine as an electric machine comprising a stator and a rotor, wherein the rotor is mounted with a commutator side bearing with an axial clearance. Such a

Rotor has a rotor shaft with an armature and a commutator, wherein the armature is energized via the commutator to generate a magnetic field between the rotor and stator for a rotational movement of the rotor. In this case, the stator may be formed with magnets in a pole housing. The rotary motion is transmitted to the engine on the output side of the rotor in order to start it.

DE 29 04 495 A1 describes a starting device of a motor vehicle with a starter motor with a stator and a rotor comprising a rotor shaft with an armature and a commutator, wherein the rotor shaft with a commutator end and stored with its other end with an axial play is.

DE 100 16 706 A1 describes a starting device of a motor vehicle with a starter motor with stator and rotor for cranking internal combustion engines. DE 40 06 797 A1 describes a starting device with a pinion for driving a sprocket of an internal combustion engine. The end of a rotor shaft of a rotor is mounted on a needle bearing and is captured by a housing cap. The opposite end of the rotor shaft includes a sun in the planetary gear. The rotor shaft is floating.

US 22 71 640 A describes an electric machine for starting an aircraft engine. On the commutator side, a deep groove ball bearing is provided as a fixed bearing.

Due to enormous cost pressure and a narrowing of tolerances in manufacturing and assembly, such a bearing has been imposed for starting devices of internal combustion engines in motor vehicles.

EP 0 819 847 A1 describes a starter with an improved lever drive. The rotor of the starter motor is attached to the side of the planetary gear with a deep groove ball bearing as a floating bearing.

It is an object of the invention to improve an electrical machine of the type mentioned in such a way so that it is resource-saving and can be produced with longer life. Disclosure of the invention

According to the invention the object is achieved by the subject matter of patent claim 1. The dependent claims define preferred embodiments of the invention.

The rotor shaft of the machine according to the invention is rotatably mounted without play at a fixed position with a fixed bearing in the context of rolling bearing air tolerances, so that reduces axial play of the rotor shaft and / or the rotor shaft is even stored without play. The reduced play reduces the space requirement of the rotor shaft in the axial direction, so that the inventive see machine with smaller dimensions, so also resource-saving, can be produced.

A floating bearing of the rotor is inexpensive and safely achieves previous requirements. To increase the number of starting device in the

To achieve start-stop operation, a fixed bearing has turned out to be particularly favorable, surprisingly. In this case, roller bearing air tolerances preferably include a tolerance of 1/100 to 1/1000 mm. Furthermore, reduced by the reduced clearance of the wear in the commutation and thus increases the life of the electric machine.

Preferably, the electric machine is a DC machine and the armature is energized via the commutator by means of brushes, wherein the brushes are arranged in the axial direction at a fixed position. In conventional electrical machines, the axial length of the commutator is increased in relation to the dimensions of the brushes in accordance with the axial play of the rotor shaft in order to ensure a tolerance compensation of the contact surfaces between commutator and brushes in the axial play.

The invention makes it possible to adapt the axial length of the commutator improved to the size of the brush, so in particular to reduce the size of the commutator and thus produce more resource-conserving, with copper can be saved as a material of the commutator. Incidentally, the reduced clearance reduces brush wear and thus increases the life of the machine. In addition, contamination of the commutator, in particular by bearing grease or oil from the commutator side bearing of the rotor, is reduced, so that the electrical resistance during commutation is not unnecessarily increased or the electrical power is reduced.

According to a preferred embodiment, the bearing on the commutator side is a fixed bearing. The commutation thus calms down, because shocks are transmitted to the rotor shaft not or at least reduced to the commutation system, such as shocks by compression and decompression of the internal combustion engine, via the drive shaft on the Rotor shaft of the starter are routed. This reduces in particular the brush wear and the life of the machine increases.

More preferably, the bearing is arranged on the commutator side at the opposite end of the output side of the rotor shaft. So it is protected from contamination by the mechanical coupling device of the rotor shaft to the output side.

Furthermore, the electric machine may have a further bearing, in particular a loose bearing, the rotor shaft, which preferably with respect to the bearing on the

Commutator side of the rotor in the axial direction along the rotor shaft on the winding side, ie to the output side, is arranged.

According to a preferred embodiment, the movable bearing in the cover or in a ring gear of the planetary gear, which except for the storage of the

Rotor shaft and a translation of the rotational movement of the rotor is used and thus by the combination of bearing and gearbox in a component is particularly resource efficient. It is preferred that the rotor shaft on the commutator, and in particular on one of the output side facing away from the end face, is fixed axially with an axially disposed screw.

Preferably, the fixed bearing according to the invention comprises a rolling bearing, in particular a ball bearing, so that the friction of the bearing is reduced and the

Lifetime and the performance of the electric machine increased.

According to a further embodiment of the invention, the fixed bearing is clamped to a housing cover of the machine. In a particularly preferred embodiment, the outer ring of the rolling bearing is clamped by the housing cover. Thus, material resources can be saved by an existing component, namely the housing cover, serves as part of the fixed bearing.

Preferably, or independently of this, the inner ring of the roller bearing is clamped in the axial direction against the rotor shaft with a holding disk and / or a screw. This allows the rotor shaft to be driven by means of fewer components. Ie produce resource-saving. Alternatively or additionally, the rotor shaft can be clamped with a U-washer, a retaining ring and / or a snap ring. In a further embodiment, the fixed bearing is arranged on the housing cover and fixed the rotor shaft through the housing cover with a screw against a retaining plate. Through the connection of the fixed bearing with the housing cover, the rotor shaft can be stored in a particularly resource-saving, since, for example, an additional holding device for the fixed bearing can be omitted.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination but also in other combinations.

Brief description of the drawings

The invention will be explained in more detail below with reference to the drawings. Show it:

Fig. 1 is a sectional view of a starter according to the invention

Bearings on the commutator side and

Fig. 2 a) - c) perspective partial views of a starter according to the invention.

Embodiments of the invention

Fig. 1 shows an embodiment of an electric machine according to the invention, namely a starter 1 for an internal combustion engine having a rotor 21 and a stator 29 in a housing 30. The rotor 21 includes an armature 3, a commutator 4 with brushes 32 and a rotor shaft 2. The rotor 21 is mounted on the output side, in Fig. 1 left, in a needle bearing 34 as a floating bearing and connected to a planetary gear 31. A bearing 25 on the commutator is as a fixed bearing, namely in the form of a

Ball bearing formed and at the opposite end of the output side arranged from the rotor shaft 2. Due to the bearing 25 on the commutator as a fixed bearing rotor shaft 2 is mounted without play in the axial direction of the commutator 4. It follows that the commutator 4 in the axial direction only slightly wider than the brush 32 must be formed. By shortened compared to conventional commutators construction resources are conserved, in particular, the material copper is reduced. The use of materials is therefore more effective than in a conventional construction. Also, a calming of the commutator is achieved and thus reduces wear and increase the life. In addition, the commutator 4 is less dirty, for example by bearing grease and oil, so that over the life of a reduced resistance in the commutation, ie a higher performance of the starter 1 is achieved.

The bearing 25 on the commutator side, ie the ball bearing, is with its outer ring of a housing cover 26 in conjunction with a closure cap

33 clamped. The inner ring of the ball bearing is clamped in the axial direction against the rotor shaft 2 with a retaining washer 27 and a screw 28, wherein the screw is formed in this embodiment as an axial extension of the rotor shaft 2 with an external thread in conjunction with a hexagon nut. The starter 1 is so easy to assemble and disassemble non-destructively, for example, for maintenance, so that the life is extended.

Another, not shown, embodiment differs from the embodiment described in FIG. 1 in that the starter 1 does not have the needle bearing 34 and instead the rotor is mounted in the cover or in a ring gear of the planetary gear 31 as a floating bearing, so that the starter 1 is thus running even more resource-efficient. FIGS. 2 a to 2 c show perspective partial views of a further embodiment of the starter 1 with the rotor 21. FIG. 2 a shows the end of the rotor 21 opposite the output side already shown in FIG. 1, along the axial direction of FIG Rotor shaft 2 to the output side, so in Fig. 2a from top to bottom, the commutator 4 is followed by the armature 3 on the rotor shaft 2 is arranged. In this embodiment, the rotor shaft 2 at this end a formed as a recessed stage La gerstelle 9 for the bearing 25 on the commutator, wherein the step is designed as a stop 10 for the bearing.

Fig. 2b shows a perspective partial view of a housing cover 6 of the starter 1 from an inner side, ie with the housing open. The bearing 25 on the commutator side is formed as a rolling bearing 5. In this embodiment, the commutator side bearing, so the rolling bearing 5, fixedly mounted on the housing cover 6 of the starter 1 with two mounting screws 11 and a roller bearing holder 12 by the outer ring of the rolling bearing 5 is clamped to the housing cover 6. In further embodiments, not shown, the rolling bearing 5 is pressed into the housing cover 6 or attached to this in a different way.

FIG. 2c shows a perspective partial view of the starter 1 in the mounted state, that is to say the housing cover 6 already shown in FIG. 2b

Outside. The rotor shaft 2 is fixed by the housing cover 6 with a screw 8 against a retaining plate 7. In this case, the screw 8 is screwed in an end-side threaded bore of the rotor shaft 2 at the output side of the opposite end, and from an outer side of the housing cover 6 from. The rolling bearing 5 is pushed onto the bearing 9.

In this case, the fixed bearing with the roller bearing holder 12 bears against the stop 10, so that a movement of the rotor shaft 2 in the axial direction to the housing cover 6 is avoided. In addition, the rotor shaft 2 is fixedly mounted by the screw 8 and the disc 7 against the inner ring of the rolling bearing 5, so that a movement in the axial direction away from the housing cover is avoided. Thus, an axial clearance of the rotor shaft 2, that is to say also of the rotor 21, is prevented. Thus, this embodiment also shows the aforementioned advantages of the commutator bearing as a fixed bearing. In particular, the commutator 4 according to the invention is shortened in the axial direction compared to a conventional commutator, thus also conserving resources, designed to be adapted to the dimensions of the brushes, not shown, and it reduces the wear of the starter 1 and increases the life. All figures show only schematic not to scale representations. Moreover, reference is made in particular to the drawings for the invention as essential.

Claims

claims

Electric machine, in particular a starter (1) for an internal combustion engine of a motor vehicle, which interacts with a meshing device, with a stator (29) and a rotor (21) having a rotor shaft (2) and an armature (3) comprising a commutator (4), and with a bearing (25) on the Kommutatorseite, characterized in that the rotor shaft (2) is rotatably mounted without play at a fixed position by means of a fixed bearing in the context of rolling bearing air tolerances.

2. Electrical machine according to claim 1, characterized in that the rolling bearing air tolerances include a tolerance of 1/100 to 1/1000 mm.

3. Electrical machine according to one of claims 1 or 2, characterized in that the bearing (25) on the commutator side is a fixed bearing.

4. Electrical machine according to one of claims 1, 2 or 3, character- ized in that the bearing (25) on the commutator side of the

Output side opposite end of the rotor shaft (2) is arranged.

5. Electrical machine according to one claims 1 to 4, characterized in that the movable bearing is in a cover or in a ring gear of the planetary gear (31).

6. Electrical machine according to one of claims 1 to 5, characterized in that the rotor shaft (2) on one of the output side facing away from the end face with an axially disposed screw (8, 28) is axially fixed.

7. Electrical machine according to one of claims 1 to 6, characterized in that the fixed bearing comprises a rolling bearing (5), in particular a ball bearing.

8. Electrical machine according to one of claims 1 to 7, characterized in that an outer ring of the bearing (25) on the commutator, in particular of the rolling bearing (5), by a housing cover (6, 26) is clamped.

9. Electrical machine according to one of claims 1 to 8, characterized in that the an inner ring of the bearing (25) on the commutator, in particular of the rolling bearing (5), in the axial direction against the rotor shaft (2) with a retaining washer ( 7, 27) and a screw (8, 28) is clamped.

10. Electrical machine according to one of claims 1 to 9, characterized in that the fixed bearing on a housing cover (26) is arranged and the rotor shaft (2) through the housing cover (26) through with a screw (28) against a retaining disk (27) is fixed.