GB2305023A

GB2305023A - Stator core and housing for an alternator

Info

Publication number: GB2305023A
Application number: GB9618029A
Authority: GB
Inventors: Stefan Lober; Hermann Lehnertz; Eugen Hellekes; Thomas Bilsing
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1995-09-02
Filing date: 1996-08-29
Publication date: 1997-03-26
Anticipated expiration: 2016-08-29
Also published as: FR2738412A1; JPH09121500A; GB2305023B; IT1283829B1; ES2116924A1; ES2116924B1; DE19532506B4; ITMI961784A0; ITMI961784A1; FR2738412B1; DE19532506A1; GB9618029D0

Description

2305023

DESCRIPTION

ELECTRICAL MACHINE The invention relates to an electric machine, more specifically an alternating current generator for motor vehicles of the generic type defined in the preamble of claim 1.

In the case of a known alternating current generator for motor vehicles of this type (DE 93 01 825 U1) the respective four projections of the three middle laminae lie in four axial recesses arranged uniformly distributed on the periphery of the one housing part and lie on the base of the recess. On the opposite side of the projections is located in each case a pillar in the peripheral region of the other housing part. The approximately semi-circular cross-section of the pillar is smaller than the likewise semi-circular crosssection of the recesses, so that the pillars are received by the recesses in order to clamp the projections between themselves and the base of the recesses. The clamping force is provided by four clamping screws which are inserted through bores in the pillars and through the through-going holes in the projections of the middle laminae and are screwed in each case into a threaded bore flush therewith in the housing part bearing the recess.

Each housing part supports a pivot arm having a bore and once the two housing parts are assembled the bores must be aligned with each other so that the alternating current generator can be attached by means of a pin to t.h6,%. motor of the motor vehicle. In order to align the bores it is necessary that the two housing parts are placed together aligned with respect tg each other. at a 1 1 \I- precise rotational angular position. This rotational angular alignment is secured by the centring unit comprising a centring spigot and a centring depression, wherein advantageously the centring spigot is achieved by increasing the width of one of the total four pillars as a centring pillar which engages as seen in the peripheral direction in a form- locking manner in the associated recess in the other housing part.

Advantages of the invention The electrical machine according to the invention having the characterising features of claim 1 has the advantage that there is a substantially higher degree of coaxiality between the tube bore and the stator bore since on the one hand the two housing parts are centred directly in a radial manner and on the other hand the stator laminated core is fixed in the one housing part. The necessary centring members are thus formed in such a manner that to finish the said centring members only tools are used whose axial direction is aligned in parallel with the machine axis, which enables the housing parts to be finished in an economical manner and in a manner suited for mass production. The machine can likewise be assembled in an economical manner and in a manner suited for mass production since it is not necessary during the screwing process for the housing parts to be so-called pegged out, i.e. it is not pre- assembled on a bearing mandrel.

Advantageous embodiments and improvements of the electrical machine set forth in claim 1 are possible by virtue of the features mentioned in the other claims.

According to a preferred embodiment of the invention the middle laminae comprise circumferential, annular contact surfaces which protrude beyond the periphery of the stator laminated core, at which contact surfaces the projections are formed as an integral part. The middle laminae lie under the pressure of the clamping screws against each other in the contact surfaces and against the annular end faces of the two housing parts. These contact surfaces of the middle laminae provide large clamping surfaces and simultaneously the clamping force on the projections is released so that the hitherto necessary milling of the housing parts in the region of the projections is omitted. Drawing The invention is explained in detail in the following description with the aid of an exemplified embodiment illustrated in the drawing in which:

Fig. 1 shows a sectioned lateral view of an alternating current generator for a motor vehicle, Fig. 2 to 5 show in each case a sectioned cross-sectional view taken along the line 11-11 and 111-111 or IV-IV and V-V in Fig. 1.

Description of the embodiments

The alternating current generator for a motor vehicle to be seen in a sectioned lateral view in Fig. 1 and in a sectioned longitudinal crosssection in -4Fig. 2 comprises, as a special case of an electric machine, a stator laminated core 10 which consists of a plurality of sheet laminae 11 and receives in a grooving 12 (Fig. 5) in a known manner a stator winding (Fig. 2) [not illustrated]. The middle three sheet laminae of the stator laminated core 10, the so-called middle laminae 14, of which a sectioned plan view is illustrated in Fig. 5, comprise in each case a circumferential, annular contact surfaces 15 [sic] which extend beyond the periphery of the stator laminated core 10 and on which are formed as an integral part four projections arranged in an identical rotational angular spaced disposition with respect to each other.

The stator laminated core 10 having a stator winding is fully encompassed by a two-piece housing 17 having the two hood-shaped housing parts 171 and 172, wherein the stator laminated core 10 is clamped between the two housing parts 171 and 172 by means of the middle laminae 14. For this purpose, the contact surfaces 15 of the three middle laminae 14 lie against each other and against the annular end faces of the two housing parts 171, 172 and the two housing parts are clamped to each other by means of the total four clamping screws 18, one of which is to be seen in Fig. 1 and 2. The clamping screws 18 are inserted in each case through a bore 19 in the one housing part 171 and through through-going holes 20 in the middle laminae 14 (Fig. 5) and screwed into the threaded bores 21 in the other housing part 172 (Fig. 2). The through-going holes 20 in the middle laminae 14 are arranged in the projections 16 of the middle laminae 14 and extend for the purpose of improving the pressing down force between the housing parts 171, 172 and the middle laminae 14 as far as into the region of the contact surfaces 15.

-5For the purpose of radially centring the two housing parts 171 and 172 and the stator laminated core 10, the one housing part 171 supports at its end facing the other housing part 172 an integral, coaxial centring connection piece 22 having an outer circumferential, turn-finished locating surface 23, whereas structural elements 24 are formed, arranged in rotational angular spaced disposition with respect to each other, on the other housing part 172, which structural elements engage with an inner curved portion 241 (Fig. 3 and 4) over the locating surface 23 in such a manner as to provide a precise fit. Moreover, at least one structural element 24 comprises in the peripheral direction mutual opposite cheeks 242 and 243 which receive between themselves essentially in a form-locking manner the congruent projections 16 on the three middle laminae 14. The structural elements 24 are cast as an integral part on the housing part 172. These centring means ensure on the one hand a high degree of coaxiality of the two housing parts 171, 172 when assembling the housing 17 and on the other hand also the coaxiality of the stator laminated core 10 in the housing 17, so that once the alternating current generator has been assembled there is an extremely precise coaxiality between the rotor and the stator bore.

As is known and not further illustrated here, a mounting arm having a mounting bore is formed as an integral part on each housing part 171, 172, wherein the two mounting arms serve to attach the alternating current generator to the motor of the motor vehicle. For this purpose, an attachment pin is inserted through the two mounting bores into the mounting arms, which requires the two mounting bores to be aligned after the house 17 has been -6assembled. In order to ensure this alignment a centring unit 25 is provided on the housing 17, the said centring unit consists of the centring spigot 27 formed as an integral part on the one housing part 172 and a centring depression 26 formed on the other housing part 171 (Fig. 1 and 4). The centring spigot 27 extends axially from the end face of a structural element 24 (Fig. 1) over the other housing part 171 and engages at the end side into the centring depression 26 at the housing part 171. The centring depression 26 receives the centring spigot 27 in the peripheral direction in a form-locking manner. (Fig. 1).

11

Claims

CLAIMS An electrical machine for motor vehicles, comprising a stator

laminated core which supports a stator winding and has a plurality of sheet laminae of which several middle laminae lying against each other support projections which comprise in each case a through-going hole and protrude radially beyond the periphery of the stator laminated core, further comprising a housing which is in two parts and encompasses the stator laminated core and the stator winding, the middle laminae of the stator laminated core being clamped between the hood-shaped housing parts of the said two part housing, wherein the clamping force is applied by clamping screws which screw the housing parts together, which clamping screws penetrate through the through-going holes and furthermore comprising a centring unit which fixes together the two housing parts in a predetermined rotational angle and which comprises a centring spigot formed as an integral part on the one housing part and a centring depression formed on the other housing part, which centring depression receives the centring spigot in the peripheral direction in a formlocking manner, characterised in that for the purpose of directly centring in a radial manner the two housing parts the one housing part supports at its end facing the other housing part an integral, coaxial centring connection piece which comprises an outer circumferential turnfinished locating surface and arranged on the other housing part

7 i 3.

in a rotational angular spaced disposition with respect to each other are structural elements which engage with an inner curved portion over the locating surface in a precise fit and that at least one structural element comprises in the peripheral direction mutually opposite cheeks which receive between themselves the projections on the middle laminae in an essentially form-locking manner. Machine according to claim 1, characterised in that the structural elements are cast as an integral part on the housing part. Machine according to claim 1 or 2, characterised in that the middle laminae comprise circumferential, annular contact surfaces which protrude beyond the periphery of the stator laminated core, the projections being formed as an integral part on said contact surfaces and that the middle laminae lie with their contact surfaces against each other under the pressure of the clamping screw and against the annular end surfaces of the two housing parts. Machine according to claim 3, characterised in that the throughgoing holes for the clamping screws lie at least partially in the region of the contact surfaces on the middle laminae. Machine according to any one of claims 1 to 4, characterised in that the centring spigot of the centring unit extends axially from the end face of one of the structural elements beyond the other housing part into the centring depression thereof.

6. An electrical machine according to any one of the preceding claims, wherein the electrical machine is an alternating current generator.

7. An electrical machine constructed and adapted to operate substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.