GB2033671A

GB2033671A - Electrical machine housing

Info

Publication number: GB2033671A
Application number: GB7936274A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1978-10-20
Filing date: 1979-10-19
Publication date: 1980-05-21
Also published as: JPS5556439A; DE2845669A1

Abstract

A machine housing is provided with end shields (16, 17), at least one of which is manufactured from sheet metal and has the shape of a disc of generally hexagonal configuration. The end shield has apertures for ventilation, for receiving rectifier diodes, and for receiving attaching means. In the form of a generator, such an electrical machine is suitable particularly for motor vehicles. <IMAGE>

Description

SPECIFICATION Electrical machine The invention relates to electrical machines.

In general, the housings of alternators for motor vehicles comprise two cup-shaped halves. The stator is fitted between the two cup-shaped halves. In each of the cup-shaped halves there is inserted a bearing for journalling the machine shaft. Conventionally, rectifier diodes are press-fitted in one of the two cup-shaped end shields, these rectifier diodes being components of a rectifier incorporated in the alternator. This known construction of an alternator has, however, a number of disadvantages. It is difficult to locate the two bearings of the machine shaft centrally relative to the stator. Moreover, it is expensive and uneconomic to fitthe diodes in a cup-shaped end shield. Furthermore, manufacture of a cupshaped end shield is costly, and is limited substantiallyto sand-casting, gravity-die casting, or pressure die-casting methods of production.

An electrical machine, according to the present invention, has a machine housing with at least one end shield made of sheet metal.

This has the advantage that the method of centering the shaft of the machine in the alternator housing is simple. A further advantage is that assembly of the rectifier components is simplified. In particular, it is possible to check the correct functioning of the diodes. Cooling of the diodes while the alternator is operating is improved. Furthermore, the end shield or shields of the electrical machine according to the present invention can be manufactured by simple, low-cost methods, such as stamping from sheet metal, pressure deep drawing, or extrusion.

The invention is further described by way of example, with reference to the drawings, in which Figure lisa longitudinal sectional view of one embodiment of an alternator for motor vehicles; Figure 2 is a plan view of one of the end shields of the alternator, and Figure 3 is a sectional view of the end shield of Figure 2.

The alternator shown in Figure 1 comprises a housing shell 11, having a pivot arm 12 and a bracing arm 13. In the housing shell 11 there is pressfitted a stator 14, having a statorwinding 15. Afirst end shield 16 and a second end shield 17 are secured respectively to the drive and slip-ring ends of the housing shell 11 by means of screws. A first bearing 18 is fitted in the first end shield 16, and a second bearing 19 is fitted in the second end shield 17. A machine shaft 21, on which there is mounted a rotor having a core 22, pole wheels 23 and an excitation winding 24, is journalled in the bearings 18, 19. On the machine shaft 21 there are also arranged a fan impeller 25, a vee-belt pulley 26, and a nut 27 serving as a clamping means.The ends of the excitation winding 24 are connected to slip rings 28, which are connected by way of brush holders 29 to a voltage regulator 31. A rectifier, having diodes 32, is serially connected to the stator winding 15. The end shields 16, 17 are provided with bearing bushes 33,34, for receiving the bearings 18, 19. Apertures 35,36, which serve for ventilation of the alternator, are provided in the end shields 16, 17.

Figure 2 is a view of the second end shield 17.

Apart from the bearing bush 34 and the ventilation holes 36, the drawing shows apertures 37, which serve to receive fastening means, such as screws, for securing the end shield 17 to the housing shell 11.

The drawing also shows apertures 38, in which rectifier diodes, such as the negative diodes of a three-phase bridge rectifier, may be press-fitted.

Figure 3 is a cross-sectional view of the second end shield 17. The first end shield 16 may be manufactured in the same manner and be of similar shape to the second end shield 17. In the embodiment of the end shield 17 as shown in Figure 2, it is evident that the end shield 17 has a radially symmetrical hexagonal periphery. The apertures 37 for the fastening means are arranged in the six corners.

Because of the hexagonal shape, the electrical connections may be offset in 60 steps to either side.

Furthermore, the housing shell 11 can be made of hexagonal cross-sectional configuration so that the round stator 14 may also be ventilated from outside through the housing shell 11.

The end shields 16, 17 are substantially discshaped. Stability with respect to oscillations along the machine shaft 21 is-ensured by the fact that their entire periphery abuts the housing shell 11. Stability may be enhanced if the edges of the ventilation holes 35,36 are flanged.

The end shields are manufactured by a massproduction press process or by a continuous press process in which the end shields are stamped from a ribbon. They may be manufactured by an extrusion method or by a moulding method.

1. An electrical machine having a machine housing with at least one end shield made of sheet metal.

2. A machine according to claim 1, in which the end shield is substantially in the form of a planar disc.

3. A machine according to claim 1 or 2, in which the end shield has thereon a bearing bush which is formed from the end shield by a forming process.

4. A machine according to any preceding claim, in which the end shield has holes for ventilation of the machine.

5. A machine according to claim 4, in which the rims of the ventilation holes are flanged.

6. A machine according to any of claims 3 to 5, in which the bearing bush and, where applicable, the edges of flanges, are formed by a deep-drawing process.

7. A machine according to any preceding claim, in which the end shield is manufactured by a production line press process.

8. A machine according to any of claims 1 to 6, in which the end shield is manufactured by a continuous press process.

9. A machine according to any preceding claim, in which apertures for the insertion of rectifier diodes are provided in one end shield.

10. A machine according to any preceding claim, in which the machine housing has a housing shell of radially symmetrical hexagonal cross-sectional con

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Electrical machine The invention relates to electrical machines. In general, the housings of alternators for motor vehicles comprise two cup-shaped halves. The stator is fitted between the two cup-shaped halves. In each of the cup-shaped halves there is inserted a bearing for journalling the machine shaft. Conventionally, rectifier diodes are press-fitted in one of the two cup-shaped end shields, these rectifier diodes being components of a rectifier incorporated in the alternator. This known construction of an alternator has, however, a number of disadvantages. It is difficult to locate the two bearings of the machine shaft centrally relative to the stator. Moreover, it is expensive and uneconomic to fitthe diodes in a cup-shaped end shield. Furthermore, manufacture of a cupshaped end shield is costly, and is limited substantiallyto sand-casting, gravity-die casting, or pressure die-casting methods of production. An electrical machine, according to the present invention, has a machine housing with at least one end shield made of sheet metal. This has the advantage that the method of centering the shaft of the machine in the alternator housing is simple. A further advantage is that assembly of the rectifier components is simplified. In particular, it is possible to check the correct functioning of the diodes. Cooling of the diodes while the alternator is operating is improved. Furthermore, the end shield or shields of the electrical machine according to the present invention can be manufactured by simple, low-cost methods, such as stamping from sheet metal, pressure deep drawing, or extrusion. The invention is further described by way of example, with reference to the drawings, in which Figure lisa longitudinal sectional view of one embodiment of an alternator for motor vehicles; Figure 2 is a plan view of one of the end shields of the alternator, and Figure 3 is a sectional view of the end shield of Figure 2. The alternator shown in Figure 1 comprises a housing shell 11, having a pivot arm 12 and a bracing arm 13. In the housing shell 11 there is pressfitted a stator 14, having a statorwinding 15. Afirst end shield 16 and a second end shield 17 are secured respectively to the drive and slip-ring ends of the housing shell 11 by means of screws. A first bearing 18 is fitted in the first end shield 16, and a second bearing 19 is fitted in the second end shield 17. A machine shaft 21, on which there is mounted a rotor having a core 22, pole wheels 23 and an excitation winding 24, is journalled in the bearings 18, 19. On the machine shaft 21 there are also arranged a fan impeller 25, a vee-belt pulley 26, and a nut 27 serving as a clamping means.The ends of the excitation winding 24 are connected to slip rings 28, which are connected by way of brush holders 29 to a voltage regulator 31. A rectifier, having diodes 32, is serially connected to the stator winding 15. The end shields 16, 17 are provided with bearing bushes 33,34, for receiving the bearings 18, 19. Apertures 35,36, which serve for ventilation of the alternator, are provided in the end shields 16, 17. Figure 2 is a view of the second end shield 17. Apart from the bearing bush 34 and the ventilation holes 36, the drawing shows apertures 37, which serve to receive fastening means, such as screws, for securing the end shield 17 to the housing shell 11. The drawing also shows apertures 38, in which rectifier diodes, such as the negative diodes of a three-phase bridge rectifier, may be press-fitted. Figure 3 is a cross-sectional view of the second end shield 17. The first end shield 16 may be manufactured in the same manner and be of similar shape to the second end shield 17. In the embodiment of the end shield 17 as shown in Figure 2, it is evident that the end shield 17 has a radially symmetrical hexagonal periphery. The apertures 37 for the fastening means are arranged in the six corners. Because of the hexagonal shape, the electrical connections may be offset in 60 steps to either side. Furthermore, the housing shell 11 can be made of hexagonal cross-sectional configuration so that the round stator 14 may also be ventilated from outside through the housing shell 11. The end shields 16, 17 are substantially discshaped. Stability with respect to oscillations along the machine shaft 21 is-ensured by the fact that their entire periphery abuts the housing shell 11. Stability may be enhanced if the edges of the ventilation holes 35,36 are flanged. The end shields are manufactured by a massproduction press process or by a continuous press process in which the end shields are stamped from a ribbon. They may be manufactured by an extrusion method or by a moulding method. CLAIMS

10. A machine according to any preceding claim, in which the machine housing has a housing shell of radially symmetrical hexagonal cross-sectional con figuration.

11. A machine according to any preceding claim, in which at least one of the end shields has a radially symmetrical hexagonal configuration.

12. A machine according to claims 10 and 11, in which apertures are provided in the corners of the hexagon formed by the radially symmetrical hexagonal configurations of the housing shell and the end shield and serve to receive fastening means by which the end shield is secured to the housing shell.

13. A machine according to any preceding claim, in which the housing has two end shields secured to opposite ends of a housing shell and both manufactured from sheet metal.

14. An electrical machine constructed substantially as herein described with reference to and as illustrated in the drawings.