GB2337866A

GB2337866A - Slipring cover for three phase alternator

Info

Publication number: GB2337866A
Application number: GB9910519A
Authority: GB
Inventors: Claus Hansen; Thomas Grabosch
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1998-05-09
Filing date: 1999-05-06
Publication date: 1999-12-01
Anticipated expiration: 2019-05-06
Also published as: ITMI990817A1; GB9910519D0; FR2778508A1; IT1312188B1; FR2778508B1; GB2337866B; DE19820885A1

Abstract

A three-phase alternator for motor vehicles is proposed, comprising a claw-pole rotor (19), the excitation winding (23) of which is supplied by means of carbon brushes via an encapsulated slipring arrangement (28, 29). In order, given an arrangement of the sliprings behind the slipring-side bearing (18) of the alternator on the free end of the rotor shaft (24), to protect said parts against dirt and moisture, the slipring compartment (38) is encapsulated by a plastic sleeve (39) which is of a substantially pot-shaped design. The slipring compartment is protected against impurities by means of a labyrinth ring (42) disposed on the rotor shaft (24) and cooperating with an annular web (41) of the plastic sleeve.

Description

2337866 Three-nhase alternator fQr vehicles

Background art

The invention proceeds from a three-phase alternator with claw-pole rotor for vehicles according to the preamble of the main claim. Such a threephase alternator is known from German Utility Model 89 11 295. Here, there is formed on the smaller-diameter part of the plastic sleeve a plurality of ventilation openings, which are distributed over the periphery and used for bearing ventilation. As a result, however, only an inadequate protection of the carbon slipring system from liquid and solid impurities (e.g. splashing water, dust, operating liquids) is possible given different angular mounting positions of the alternator.

Advantages of the invention In contrast, the threephase alternator according to the invention having the characterizing features of the main claim has the advantage that an annular labyrinth prevents solid and liquid impurities from penetrating into the slipring compartment, that abraded carbon matter from the carbon brushes may pass through the labyrinth gap to the outside and that ventilation and cooling of the slipring compartment are possible via the labyrinth gap.

Further advantageous refinements of the invention are evident from the following description, the sub-claims and the drawings.

2 Drawings Figure 1 shows a longitudinal section through a three-phase alternator and a plastic sleeve encapsulating the slipring compartment, Figure 2 the plastic sleeve in longitudinal section, Figure 3 a plan view of the plastic sleeve according to Figure 2 and Figure 4 a section through a labyrinth ring.

Description of the embodiment

The three-phase alternator for motor vehicles, which is shown in longitudinal section in Figure 1, substantially comprises a stator 10 in the form of a laminated core, which carries a three-phase stator winding 11 and is fastened to the two housing shells 12, 13 by means of screws 14. The housing shells 12, 13 at their end faces form end shields 15, 16, in which at the drive end A a relatively large drive bearing 17 and at the brush end B a weaker slipring bearing 18 is installed. Disposed rotatably in the stator 10 is a claw-pole rotor 19, which comprises two claw-pole disks 20, 21, between which is clamped a flux concentrating piece 22, onto which an excitation winding 23 is mounted. The claw-pole rotor 19 is pressed onto a rotor shaft 24, which is accommodated in the two bearings 17, 18 and at the drive end A has a threaded projection 25 for the purpose of fastening a driving pulley. Fastened on either side of the claw-pole rotor 19 on the rotor shaft 24 is a ventilator disk 26, 27 for the removal of heat loss of the three-phase alternator.

Provided at the brush end B of the rotor shaft 24 is a slipring arrangement comprising two sliprings 28, 29 situated with clearance alongside one another, which are 3 fastened so as to be insulated from one another and from the rotor shaft 14 on the latter and are connected by conductors (not shown) run in an insulated manner in the rotor shaft 24 to terminals 30 which, for supplying power to the excitation winding, are contacted with the latter's line ends 31. At the outside of the end shield 16 of the brush- side housing shell 13 a rectifier unit 32, which is not shown in detail, is fastened by means of screws 33 and, moreover, a brush holder 34 having the carbon brushes (not shown) for the sliprings 28, 29 as well as a voltage regulator 35 are attached and connected up. Said structural unit is finally additionally enclosed by a potshaped cap 36, which is likewise fastened to the brushside housing shell 13 and accommodates the electrical connections 37 of the alternator.

For moisture- and dirtproof encapsulation of the slipring compartment 38, a plastic sleeve 39 illustrated in Figures 1 to 3 is provided, which for receiving the brush holder 34 has an opening 40, which is sealed in an outward direction by a sealing ring 41 at the bottom end of the brush holder 34. The plastic sleeve 39 is closed by a base 39A at its outer end so that in a pot-like manner it surrounds the sliprings 28, 29 disposed behind the slipring bearing 18 on the free end of the rotor shaft 24.

As Figures 2 and 3 in particular reveal, the plastic sleeve 39 comprises a rear part 39B adjoined by a front part 39C, which has a much larger diameter than the part 39B. Said part 39C is also referred to as the bearing fit ring because it receives the bearing 18, i.e. the outer ring of the.beaiing 18 lies against the inside of the part 39C in said regard, see Figure 1. Formed at the transition from part 39B to part 39C and extending towards the bearing 18 is a relatively short annular collar 39D.

4 It engages into an annular groove 46 of a labyrinth ring 42, which is disposed on the rotor shaft 24 and lies with a short collar 43 against the inner ring of the bearing 18. Said labyrinth-like sealing arrangement prevents solid and liquid impurities from being able to penetrate into the slipring compartment 38. Furthermore, abraded carbon matter from the carbon brushes may pass out through the labyrinth gap and ventilation and cooling of the slipring compartment are achieved via the labyrinth gap. The plastic sleeve 39 moreover has, formed on the part 39C close to the transition to part 39B, a plurality of holes 44 through which liquid, which has arisen as a result of condensation and has penetrated e.g. through the bearing seat, is removed. The holes 44 lie level with the labyrinth ring 42 so that liquid which may have penetrated there is slung back out by the rotating labyrinth ring.

Situated between the bearing 18 and the claw poles and forming an integral part of the rotor shaft 24 is a slinger 45, which lies in the region of the open end of-the plastic sleeve 39. In said region, there is formed both on the inner periphery of the plastic sleeve 39 as well as on the outside of the slinger 45 an annular bevel 45a and 46 respectively. Said means likewise prevent impurities from being able to penetrate into the slipring compartment 38. Rather, they are slung outwards by the rotating slinger 45.

Claims

Claims

Three-phase alternator for vehicles, comprising a rotor, preferably a claw-pole rotor, the excitation winding of which is supplied by means of carbon brushes via an encapsulated slipring arrangement (28, 29), wherein the encapsulation of the slipring compartment (38) is effected by means of a plastic sleeve (39), which is attached to one of the fixed alternator parts - housing shell for a rotor bearing, rectifier unit or cap - and has a sealed opening for receiving a brush holder (34), wherein the plastic sleeve (39) is closed at its outer end (39A) so that in a pot- like manner it surrounds the sliprings (28, 29) disposed behind the slipring-side bearing (18) on the free end of the rotor shaft (24) and has at least one ventilation opening (44) in front of the bearing point of the rotor shaft, characterized in that the plastic sleeve (39) at its inside has an annular collar (39D), which is directed towards the slipring-side bearing (18) and engages into an annular groove (46) of a labyrinth ring (42), which isdisposed on the rotor shaft (24) in front of the bearing (18).
Alternator according to claim 1, characterized in that the plastic sleeve comprises a bearing fit region (39C), which accommodates the bearing (18) and against the inside of which the outer ring of the bearing lies, and that formed in the bearing fit ring 6 is at least one hole (44) for the removal of liquid impurities, which lies substantially level with the labyrinth ring (42).
3.

Alternator according to claim 1 or 2, characterized in that situated on the rotor shaft (24) is a slinger (45), which lies between the bearing (18) and the claw poles of the alternator.
4. Alternator according to claim 3, characterized in that the slinger (45) is an integral part of the rotor shaft (24).
5.

Alternator according to one of claims 1 to 4, characterized in that a runoff bevel (46) is formed level with the slinger (45) on the end of the plastic sleeve (39) directed towards the claw poles.
6. An alternator substantially as herein described with reference to the accompanying drawings.