GB2268546A

GB2268546A - Sealing electric machines

Info

Publication number: GB2268546A
Application number: GB9313084A
Authority: GB
Inventors: Dieter Berghaenel; Claus Hansen; Thomas Bilsing; Gerhard Schoeber
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1992-07-03
Filing date: 1993-06-25
Publication date: 1994-01-12
Anticipated expiration: 2013-06-25
Also published as: GB9313084D0; FR2693324B3; GB2268546B; FR2693324A3; ES1025198Y; IT230319Y1; ITMI930533V0; ES1025198U; ITMI930533U1

Abstract

An electric machine, preferably a three-phase generator for motor vehicles, comprises belt pulley (17), which is attached to the drive-side end of the machine shaft (15) and which includes flinger disk (19) disposed in advance of the drive-side ball bearing (11) to protect the bearing against spray water. An axially outwardly directed annular collar (20) is formed on the bearing flange (10). The outer edge of the finger disk may be curved towards the bearing flange, and may be provided with a plurality of radial slots distributed over its periphery. <IMAGE>

Description

DESCRIPTION Electric machines The invention relates to electric machines, and in particular, but not exclusively, to three-phase generators for motor vehicles.

An electric machine is known from Fig. 1 of DE-GM 89 152 12, in which the drive-side ball bearing is held with its internal race sitting on the machine shaft between an annular shoulder of the machine shaft and a spacing ring, against which the belt pulley is firmly held at the end of the machine shaft. At the same time, the spacing ring forms at its outer periphery an annular gap with the thrust ring which is attached at the bearing flange and which covers the ball bearing towards the front, in order to protect the ball bearing internal chamber which is filled with grease from being sprayed with water.The rear region of the so-called grooved belt pulley of the machine forms at the same time a type of flinger disk for the purpose of throwing off the spray water, because the water penetrating between the thrust ring and the belt pulley during the operation of the machine is thrown off towards the outside from the rear side of the rotating belt pulley. As shown in Fig. 2 of this document, the thrust ring of the ball bearing is replaced by an annular shoulder on the housing flange and the belt pulley is formed from a piece of sheet metal, whereby the water which also penetrates therebetween the housing flange and the belt pulley as far as the bearing bore should be thrown off radially towards the outside by virtue of the rear-side surface of the belt pulley.

These solutions are, however, not completely satisfactory when using the electric motor in a motor vehicle, since they would be subjected to heavy spray water or even gushes of water, in particular when washing the engine, so that, when the engine is stationary, water penetrates through the annular gap between the bearing bore and the spacing ring into the ball bearing but is no longer able to run out of the thrust ring and/or the housing collar covering the ball bearing.

The invention endeavours to improve the protection of the drive-side bearing of electric motors from spray water in the most economical manner.

In accordance with the present invention there is provided an electric machine for a motor vehicle, having a self-mounted rotor and a belt pulley which is attached to the drive-side end of the machine shaft, the belt pulley having an integral flinger disk for throwing off spray water, the flinger disk being disposed in advance of the drive-side ball bearing and overlapping the bearing bore of a machine housing part, wherein an axially outwardly directed annular collar which serves as a spray water drip edge is formed in a concentric manner at the bearing bore in the bearing region of the machine housing part, which collar extends in the axial direction in a sealing manner as far as the flinger disk, and the flinger disk has a larger external diameter than that of the annular collar.

This renders it possible for the water penetrating between the bearing flange of the machine and the belt pulley to run on to an annular collar at the bearing flange and/or at the housing part of the electric motor supporting the bearing, wherein this annular collar encompasses the bearing bore as a drip edge in a concentric manner at a slight distance to the belt pulley. The majority of the water from the lower region of the annular collar therefore drips off from here and the remainder passes into the annular gap formed between the flinger disc and the annular collar, from where it is thrown off towards the outside by virtue of the rotating belt pulley.The annular shoulder at the bearing bore is selected in such a way that it only covers the outer race of the ball bearing, forming in this way an axial stop for the 1)111 bearing And revealing th rotating region of the bearing. In this way, when the engine is stationary, any water from washing installations or when washing the engine which advances as far as the ball bearing can flow away immediately in the downwards direction by way of the annular collar.

The travel of the water to the ball bearing is thus extended and/or rendered more difficult if at least two annular shoulders with different diameters protrude behind the flinger disk in the direction of the axis into the front region of the bearing bore, wherein at least the larger annular shoulder with the bearing bore forms a small annular gap. A labyrinthtype annular gap formed between the annular shoulder and the bearing bore region renders it possible, that the annular shoulder with the larger diameter first follows behind the flinger disk followed by the annular shoulder with the smaller diameter, and that both annular shoulders engage in a corresponding stepped bearing bore region.The smallest possible axial distance between the flinger disk and the annular collar is set in a simple manner by the fact that a further annular shoulder having a still smaller diameter rests at the front side against the internal race of the ball bearing.

A particularly advantageous solution resides in the fact that the annular shoulder having the smaller diameter first follows behind the flinger disk followed by the annular shoulder having the larger diameter, wherein the annular shoulder lying directly behind the flinger disk forms a run-off groove for the water having penetrated behind the flinger disk.

A further advantageous solution for the protection of the bearing against spray water and gushes of water resides in the fact that the outer edge region of the flinger disk protruding beyond the annular collar of the bearing flange is curved towards the bearing flange, so that it lies in a sealing manner over the annular collar and terminates in a sealing manner in front of the wall of the bearing flange.

By way of example only specific embodiments of the present invention will now be described with reference to the accompanying drawings, in which: Fig. 1 illustrates a cross-sectional view of the drive-side part of a three-phase generator for motor vehicles having a drip edge bordering the bearing bore and a labyrinth-type air gap between the bearing bore and the belt pulley; Fig. 2 illustrates a cross-sectional view of the drive-side part of the three-phase generator having a drip groove at the belt pulley, which is disposed below the drip edge at the bearing bore immediately behind the flinger disk; and Fig. 3 illustrates a cross-sectional view of a generator with an edge portion of the flinger disk curved over the annular collar of the bearing bore.

Fig. 1 illustrates the upper half of the threephase generator for motor vehicles with a partial sectional view of its drive-side housing part 10 formed as a bearing flange. A drive-side ball bearing 11 is received here with its outer race in a bearing bore 12 of the housing part 10, the bearing bore 12 being covered at the front by an annular shoulder 13 of the housing part and at the rear by a thrust ring 14. The internal ring of the ball bearing 11 sits on a machine shaft 15 of the self-mounted rotor of the machine, wherein the internal race of the ball bearing 11 is held between an annular shoulder 16 of the shaft 15 and a grooved belt pulley 17, which is fixedly screwed at the end of the shaft 15 by virtue of a nut 18. For the purpose of protecting the ball bearing 11 from spray water, a flinger disk 19 is formed at the rear end of the belt pulley 17 and the flinger disk 19 covers at the front side the bearing bore 12 and all the annular shoulder 13. Moreover, in order to improve the protection of the ball bearing 11 against water penetrating the bearing region, the annular shoulder 13 of the housing part 10 of the machine is provided with an axially outwardly directed annular collar 20, which extends in the direction of the axis to fit in a sealing manner in front of the flinger disk 19. The annular collar 20 serves as a drip edge for any spray water which penetrates between the housing part 10 and the belt pulley 17.In order to keep any spray water approaching at the front side in a diagonal direction away from the bearing area, the flinger disk 19 having a larger outer diameter is provided as the annular collar 20 at the housing part 10.

Two annular shoulders 21, 22 having different diameters are formed on the belt pulley 17 at the rear of the flinger disk 19 seen from the axial direction of the machine. The two annular shoulders 21, 22 form a small annular gap 23 with the front part 12a of the bearing bore 12. The annular shoulder 21 having the larger diameter is formed first behind the flinger disk 19 and the annular shoulder 22 having the smaller diameter is then formed. The two annular shoulders 21 and 22 engage at the same time in a correspondingly stepped front region 12a of the bearing bore 12, so that a labyrinth-type annular gap 23 is formed between the bearing bore region 12a and the annular shoulders 21, 22.In order to be able to adjust as precisely as possible the axial gap between annular shoulder 13 of housing part 10 and the rotating flinger disk 19, a further annular shoulder 24 having a still smaller diameter is formed at the rear end of the belt pulley 17 and this further annular shoulder 24 rests at the front side against the internal ring of the ball bearing 11. Consequently, when installing the ball bearing 11 in the bearing bore 12 of the machine, the axial distance of the flinger disk 19 from the annular collar 20 encompassing the bearing bore in a concentric manner is fixedly predetermined. The axial space can be as small as the manufacturing tolerances in the bearing region of the machine and/or on the belt pulley 17 allow.Nonetheless, should water penetrate by way of the annular gap 23 into the chamber 26 in advance of the bearing 11, then it can immediately flow away downwards.

In the case of a second embodiment of the invention as shown in Fig. 2, those parts which are identical to parts as shown in Fig. 1 have identical designations. In contrast to Fig. 1, the front region 12a of the bearing bore 12 is not stepped at the level of the annular collar 20. Moreover, the annular shoulder 22 having the smaller diameter is formed first behind the flinger disk 19 of the belt pulley 17 and then the annular shoulder 21 having the larger diameter is formed. Consequently, the annular shoulder 22 lying directly behind the flinger disk 19 forms a drip groove 25 for any water which has penetrated behind the flinger disk 19. At the same time, the larger annular shoulder 21 formed behind the drip groove 25 forms a small annular gap 23 with the bearing bore region 12a surrounding it.As soon as any water penetrates into the axial gap between the flinger disk 19 and the annular collar 20 during the operation of the machine, then this water flows into the drip groove 25 from where it is thrown off in an outwardly direction by virtue of the flinger disk 19.

Water can also arrive at the bearing region of the machine when the machine is stationary, for example, when washing the engine or in a motor vehicle washing installation, wherein this water can also first arrive by way of the drip edge of the annular collar 20 into the drip groove 25 of the belt pulley 17 disposed thereunder and from there, the water drips off in a downwards direction, so that it is not able to advance by way of the annular gap 23 to the bearing 11.

At the same time, it is advantageous for the assembly of the electric machine, if the flinger disk 19 is manufactured as one piece with the annular shoulders 21, 22, 24, lying behind the flinger disk v 19, and the belt pulley 17. The solution in accordance with the invention, however, also renders it possible to manufacture the annular shoulders 21, 22 and 23 behind the flinger disk 19 in each case individually or jointly as additional parts and if necessary they can be fixedly held in a desired sequence between the ball bearing 11 and the belt pulley 17.

In the case of the third embodiment of the invention as shown in Fig. 3, those parts which are identical to parts shown in Fig. 1 are likewise designated with identical numbers. An improved protection for the ball bearing 11 of the electric machine against spray water and gushes of water is achieved by the fact that the outer edge region 19a of the flinger disk 19 protrudes beyond the annular collar 20 of the housing part 10 formed as a bearing flange, the flinger disk is curved towards the housing part, so that it extends in a sealing manner over the annular collar 20 and in a sealing manner as far as the wall of the housing 10. The annular gap 23 formed in this way between the flinger disk 19 and the annular collar 20 is likewise so small in cross section, that, should the situation arise, only a small amount of spray water and/or gushing water can penetrate from the upper region by way of the annular gap 23 into the chamber 26 in advance of the bearing 11. This water can then flow away again immediately downwards through the annular gap 23.

In order to facilitate the drainage of any water which has possibly penetrated the chamber 26, four slots 27 which are uniformly distributed on the periphery are also provided in the curved edge region 19a of the flinger disk 19 and these slots 27 are radially cut into and/or punched into the curved edge region 19a of the flinger disk 19 in an advantageous manner.

Claims

1. An electric machine for a motor vehicle, having a self-mounted rotor and a belt pulley which is attached to the drive-side end of the machine shaft, the belt pulley having an integral flinger disk for throwing off spray water, the flinger disk being disposed in advance of the drive-side ball bearing and overlapping the bearing bore of a machine housing part, wherein an axially outwardly directed annular collar which serves as a spray water drip edge is formed in a concentric manner at the bearing bore in the bearing region of the machine housing part, which collar extends in the axial direction in a sealing manner as far as the flinger disk, and the flinger disk has a larger external diameter than that of the annular collar.

2. An electric motor according to claim 1, wherein at least two annular shoulders lie axially behind and are connected to the flinger disk, the shoulders have different diameters and protrude into the front region of the bearing bore, wherein at least the larger annular shoulder forms a small annular gap with said front region of the bearing bore.

3. An electric machine according to claim 2, wherein a further annular shoulder having a still smaller diameter than said smaller and larger diameters shoulders is disposed behind said shoulders and rests at the front side against the internal race of the ball bearing.

4. An electric machine according to claim 2 or 3, wherein the larger annular shoulder lies nearer the flinger disk than the smaller annular shoulder and both annular shoulders engage in a correspondingly stepped region of'the bearing bore, so that a labyrinth-type annular gap is produced between the bearing bore region and the said annular shoulders.

5. An electric machine according to any one of claims 1 to 3, wherein the smaller annular shoulder lies nearer the flinger disk than the larger annular shoulder, and the smaller annular shoulder lying directly behind the flinger disk below the drip edge forms a drip groove for any water which has penetrated behind the flinger disk.

6. An electric machine according to any one of claims 1 to 5, wherein the flinger disk, the smaller, larger and further annular shoulders lying behind the flinger disk and the belt pulley are manufactured as one piece.

7. An electric machine according to any one of claims 1 to 6, wherein the outer edge region of the flinger disk protruding beyond the annular collar of the machine housing part is curved in a sealing manner over the annular collar towards the machine housing part.

8. An electric machine according to claim 7, wherein the curved edge region of the flinger disk has a plurality of radial slots distributed over its periphery.

9. An electric machine constructed and adapted to operate substantially as described herein with reference to and as illustrated in, the accompanying drawings.