GB2330013A

GB2330013A - An electrical generator having a pressure equalizing duct formed in the plug b se of the regulator

Info

Publication number: GB2330013A
Application number: GB9816967A
Authority: GB
Inventors: Hans-Peter Miller; Gerhard Pflueger; Erich Wolf; Juergen Lechner; Wolfgang Gottfried; Rainer Brachert; Oliver Eckert; Thomas Lengenfelder
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1997-09-30
Filing date: 1998-08-04
Publication date: 1999-04-07
Anticipated expiration: 2018-08-04
Also published as: DE29717415U1; GB9816967D0; FR2769146A1; FR2769146B1; JPH11155251A; GB2330013B; IT1302255B1; JP4235289B2; ITMI982054A1

Abstract

A three-phase electrical generator of the conducting piece rotor type with a stationary exciting winding 24 and a pole wheel 19 which is connected to a drive shaft 18,18A. Each end of the drive shaft is mounted in a ball bearing 13, 16 which in turn is disposed in the generator housing 10, 11. One of the ball bearings 13 is mounted in an end shield 11 which acts as a negative heat sink. A positive heat sink 28 , of a rectifier unit with its negative and positive diodes, is secured to the outside of the end shield, as is a connection plate 32 wherein a regulator 39, for regulating the generator, is provided. The regulator 39 has a plug base 42. These parts are surrounded by a protective cap 34 which is connected in a water tight manner to the end shield 11. The interior of the generator is also sealed off from the outside through appropriate sealing means. The interior space of the generator is vented via a pressure equalising duct 41 formed in the plug base 42 of the regulator 39.

Description

2330013 1 Electrical machine. in particular a three-phase generator

without slip rings Pri, or art The invention is based on an electrical machine, in particular a three- phase generator without slip rings accor ding to the type of claim 1. When known electrical machines of this kind are fitted in a cross-country vehicle in particular and this is capable of also moving through water, it is possible for moisture to enter the generator, which causes it to fail. The vehicle is then no longer in running order.

Advantages of the invention In contrast, the electrical machine according to the invention, as characterised mi claim 1, has the advantage of beffig impenetrable to moisture through appropriate measures, even if the vehicle carrying it is soaked through, i.e. the generator lies below the surface of the water. This property is also called fording ability. The measures which this requires entail relatively little expenditure.

Further advantages of the invention will emerge from the subclaims, the following description and the drawings.

Drawings Figure 1 of the drawings is a section through a three-phase generator withb, rings, Figure 2 is a plan view onto the end shield of the generator, Figure 3 is a section through a detail at the drive end shield, 2 Figure 4 is a side view in the direction of the arrow according to Figure 2.

Description of the embodiment

The three-phase generator according to Figure 1 of conducting piece rotor type has a housing consisting of an approximately pot-shaped housing part 10, which is closed by an end shield 11 - which is also called a negative heat sink for negative diodes, which are disposed on this, of a rectifier unit. A ball bea ring 133 is disposed in a shouldered bore 12 formed in the end shield 11, while a further ball bearing 10 16 is seated coaxially with the beafing 13 in a convex pan 15 moulded onto the housing pot 10. The shaft 18 of a pole wheel 19 (claw-pole rotor), which is integral with it, is mounted 'm the two ball bearings. Projecting out of the end shield 11 is a tapered shaft end 18A of the shaft 18, to which a belt pulley 20 for driving the generator is secured.

The generator is of the conventional type, comprising a stator core 22, a pole body 23 with a stationary exciting winding 24, and a rotating conducting piece 26, which is fninly connected to the pole wheel 19 via a non-magnetic ring 25.

Air gaps between the above-mentioned parts are not designated in detail, as these are conventional and not essential for the invention.

A so-called positive heat sink 28 for the positive diodes of the rectifier unit is secured by screws 29 to the end shield 11 coaxially with the latter. An insulating sheet 30 lies between the two parts. The heads 29A of the screws 29 point outwards, i.e. towards the belt pulley. A connection platt. 32 is located radially within the heat sink 28, again also coaxially with the latter, and is secured to the end shield 11 by cheese-head screws 33, Le, the heads of the cheese-head screws 3 also point outwards. The parts mentioned last are located under a protective cap 3) 4, the inside diameter of which embraces a plate 3) 5, while its outside diameter engages in an annular groove'-') 7 in the end shield 11. This is considered in detail in the following. However there will firstly be a discussion of Figures 2 and 4, which represent the end shield 11, in a plan view in Figure 2 and in a side view in Figure 4 (direction of arrow G Mi Figure 2). The regulator housing is designated by 40. This has a plug base 42 and a pressure equalising duct 41 - see Figure 4 which connects the interior space of the generator on the outside to a cable harness, which is not shown, inserted in the plug base 42 and also used for pressure equalisation. The plug, which is not shown either, seals the plug connection at the plug base 42. The purpose of this arrangement is discussed in the following, although several important details are to be described beforehand.

is As initially mentioned, a vehicle provided with the generator according to the invention may get into situations, for example when crossing a body of water, in which the generator lies below the surface of the water. The above- mentioned pressure equalisation prevents the occurrence of an underpressure in the generator due to temperature changes, so that no corrosion products can enter the generator.

An arrangement of this kind is called fording ability. In this case pressure equalisation takes place via the air volume in the cable harness through the pressure equalising duct 41 into the interior space of the protective cap 34 and via bores in the end shield for passmig connections through to the interior space of the generator.

However only a few further measures are required to prevent liquid from entering the generator, these relating to the sealing of the generator housing interior. For this purpose it is important for the protective cap 34 to be sealed off from the end shield 11. This is effected by providing a seal 44 in the groove 37, in which a rim 4 extending round the outer circumference of the protective cap 34 engages. Also important is the seal 49 at the outer race of the ball bearmig 13 between the plate and the end shield 11 and seals 56 at the regulator housing. A sealmig ring 53, which seals off the generator housing towards the internal combustion engine side, also lies in an annular groove 52 at an outer flange 51 of the housing 10. It was therefore considered important to systematically seal all the generator parts against the penetration of liquid. The above-mentioned pressure fluctuations in the generator due to temperature changes, i.e. when the vehicle enters the water with the generator and is cooled, and the pressure fluctuations which this causes necessitate pressure equalisation which - as mentioned above - takes place through the pressure equalising duct 41 mi the regulator housmig 40 and through the cable harness.

Figures 2 and 3 will also be discussed for the sake of completeness, Figure 2 also is showing the sealing means 55 between the end shield 11 and the protective cap 3)4, sealing means 56 at the regulator housing 40 and sealing means 57 at an anti interference capacitor 59, which is not shown in detail. The rear ball bearing 16 is mounted in the stator housing 10 via a fitting ring 58. The plate 35 at the front bearing 13 is secured to the end shield 11 by countersunk screws 6 1. It is sealed by seals 60 according to Figure 3.

Claims

Electrical machine, in particular a three-phase generator without slip rings, of the conducting piece rotor type with a stationary exciting wmiding (24) and a pole wheel (19) which is connected to the drive shaft (18, 18A) and has a preferably integral conducting piece (26), wherein the drive shaft is mounted on both sides in ball bearings (13, 16) which are disposed mi the generator housing (10, 11), one of which in the end shield (11) on the drive side, which serves as a so-called negative heat sink to the outside of which a so-called positive heat sink (28) of a rectifier unit with its negative and positive diodes is secured, as well as a connection plate (32) screwed to the outside of the end shield (11), wherein a regulator (39), which is provided with a plug base (42), for regulating the generator is disposed on the outside of the end shield (11) and these parts are surrounded by a protective cap (34) secured to the end shield, characterised mi that is the protective cap (34) is connected in a watertight manner via sealing means to the end shield ( 11), and that a pressure equalising duct (4 1), which extends mito the space of the protective cap (34), is formed in the plug base (42) of the regulator (39).

2. Machine according to claim 1, characterised in that the protective cap (34) has an annular collar (45) which projects into an annular groove (37) in the end shield (11) and is surrounded all round and on both sides by a sealant (44).

Machine according to one of claims 1 and 2, characterised in that the ball bearing (13) and the end shield (11) are sealed off from a plate (35), which is embraced in a sealing manner by the protective cap (34), by sealing means (49).

6 4. Machine according to one of claims 1 to.3, characterised in that pressure equalisation in the generator is effected through the pressure equalising duct (41) at the plug base (42) of the regulator (39) via a cable harness hose of an appropriate length which is to be mounted at this point and leads to the outside.

5. is liquid-cooled.

Machine according to one of claims 1 to 4, characterised in that it 6. Machine according to one of claims 1 to 5, characterised 'm that a sealing ring (53) is disposed in an annular groove (52) at an outer flange (5 1) of the housing pot (10) of the generator, which ring seals off the generator from the internal combustion engine when it is fitted to the latter.

7. An electrical machine substantially as herein described with reference to the accompanying drawings.