GB1560746A

GB1560746A - Electrical machines

Info

Publication number: GB1560746A
Application number: GB4474876A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1975-10-29
Filing date: 1976-10-28
Publication date: 1980-02-06
Also published as: IT1072877B; AU1909776A; BR7607168A; JPS5254905A; DE2548313A1; AU504654B2; FR2330186A1

Description

(54) IMPROVEMENTS IN OR RELATING TO ELECTRICAL MACHINES (71) We, ROBERT BOSCH GmbH, a German Company, of Postfach 50, 7000 Stuttgart 1, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to an electrical machine.

Electrical machines are known which have claw-pole rotors, a magnetic flux being "fed" to the rotatable claws by a fixed excitation system by way of interposed air gaps. The rotatable claws have to be separated from one another. Hitherto, when manufacturing the claw-pole rotor for a machine of this type, the pole core and the pole disc and the two pole rings were first manufactured, these parts then being assembled. A hole for the generator shaft was then bored in the pole core and in the pole disc, or the hole already provided during manufacture was bored to the final dimension. Finally, the generator shaft was brought to the accurate finished dimension and assembled with the pole core and the pole disc. Thus, the manufacture of a claw-pole rotor of this type required a large number of working operations and a high degree of manufacturing accuracy.

According to the present invention there is provided a slipringless electrical machine comprising a stator pole assembly, a clawpole rotor assembly rotatable within the stator pole assembly, a rotor bearing at each end of the claw-pole rotor assembly, and a fixed excitation system which includes an excitation ring and an excitation winding, the claw-pole rotor assembly comprising an integral pole core and pole carrier disc manufactured from a single piece of metal and a stub shaft connected to the pole core at one end thereof and journalled in the respective bearing.

A particular advantage of the present invention is that accurate machining of the stub shaft is unnecessary. A further advantage is that the accurate manufacturing tolerances can be obtained by simple and conventional manufacturing methods.

The invention will hereinafter be further described by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a part sectional view of an electrical machine in the form of an alternator for a motor vehicle, as disclosed in the complete specification of our copending Patent Application No. 44749/76.

Fig. 2 shows a cross section through a pole core and pole carrier disc of an electrical machine in accordance with one embodiment of the present invention, Fig. 3 illustrates the insertion of stub shafts into recesses in the pole core of Fig. 2, Fig. 4 is a cross section through an alternative form of pole core, for a machine according to another embodiment of the present invention, and also shows an alternative means by which a stub shaft may be fixed into a recess in a pole core, and Fig. 5 shows the pole core and pole carrier disc of Fig. 4 joined to pole rings.

Referring to Fig. 1, the housing of a motor vehicle alternator includes a bearing plate 11 at the drive end and a bearing plate 12 remote from the drive end. A stator 13 is clamped between the bearing plates 11 and 12. The stator 13 carries a phase winding 14.

The bearing plate 12 carries an excitation system having an excitation ring 15 and an excitation winding 16. A claw-pole rotor assembly comprises a shaft 17 journalled in respective bearings in the bearing plates 11 and 12, a core 18 carried by the shaft, a first pole ring 19 which is mounted on a pole carrier disc 20 integral with the core 18, and a second pole ring 21. Furthermore, a cooling plate 22 having rectifier diodes 23, and a voltage regulator 24 are mounted on the bearing plate 12. Only a single diode 23 is shown in Fig. 1, six main current diodes and three excitation current diodes normally being required for a three-phase generator.

Furthermore, a circuit board 25 is provided.

The circuit board 25 carries conductor paths (not illustrated in Fig. 1) which serve to connect the ends 26 of the phase winding 14 to the associated electrodes of the diodes 23.

Furthermore, the circuit board 25 carries a spring contact 27 which, when the generator is in its assembled state, is in contact with a corresponding spring contact 28 of the voltage regulator 24 and thus establishes an electrical connection between the voltage regulator 24 and the circuit board 25. The ends 31 of the excitation winding 16 are connected to associated contacts on the circuit board 25, and thus to the spring contact 27.

Figs. 2 and 3 illustrate one embodiment of the present invention. Fig. 2 shows a unit comprising the pole core 18 and the pole carrier disc 20 which has been manufactured from a blank 32 by any suitable means such as drop-forging. Recesses 34 and 35 have at the same time been formed along the axis 33.

A first of the recesses 34 has a larger diameter for a stub shaft at the drive end, and a second of the recesses 35 has a smaller diameter for a stub shaft at the end remote from the drive end.

Fig. 3 shows the next step, namely the insertion of the stub shafts. A first stub shaft 36 is inserted into the first recess 34, and a second stub shaft 37 is inserted into the second recess 35. In the embodiment shown in Fig. 3, the two stub shafts 36,37 are provided with milled portions 38, 39. Alternatively, however, other mechanical connection means may be used. By way of example, the stub shafts may be connected to the core by butt-welding, by friction welding, by electric welding or by shrink-fitting.

The claw-pole rotor assembly comprising the core 18, the carrier disc 20 and the stub shafts 36, 37, together with two claw-pole rings as shown in Fig. 1, is then journalled by the stub shafts in rotor bearings at opposite ends of the rotor.

Fig. 4 first shows a further possibility of securing the first stub shaft 36 in the first recess 34. The first stub shaft 36 has a bore 41 in line with its axis 33. A taper plug 42 is additionally provided. Upon pressing the first stub shaft 36 into the first recess 34, the taper plug 42 is pressed into the bore 41 and widens the end of the first stub shaft 36.

Thus, the first stub shaft 36 is securely connected to the pole core 18 in the first recess 34.

However, Fig. 4 also shows a further embodiment of the invention. By suitable deforming measures, the first recess 34 is formed at one end of the blank 32 in line with the axis 33, and a stub shaft 43 is integrally formed with the pole core 18 at the other end. The stub shaft 43 replaces the second stub shaft 37 of the embodiment of Fig. 3.

Fig. 5 shows the assembly comprising the pole core 18, the pole carrier disc 20 and the pole rings 19 and 21. The pole rings 19 and 21 are interconnected by means of nonmagnetic intermediate members 44, and the assembly comprising the pole rings 19, 21, interconnected in this manner, is pressed onto the pole carrier disc 20 and is secured thereto by means of a welded joint 45.

In the complete specification of our copending patent application No. 44749/76 (Serial No. 1560747) we have claimed a slipringless electrical machine comprising a stator pole assembly, a claw-pole rotor assembly rotatable within the stator pole assembly, and a fixed excitation system including an excitation winding, the clawpole rotor assembly having a pole disc, a first pole ring mechanically and magnetically connected to the pole disc, and a second pole ring which is only mechanically connected to the first pole ring, the fixed excitation system co-operating at least indirectly with the pole disc and with the second pole ring, each pole ring comprising a plurality of claws and bridge portions between the claws, at least one of the pole rings being formed from a strip.

WHAT WE CLAIM IS:1. A slipringless electrical machine comprising a stator pole assembly, a claw-pole rotor assembly rotatable within the stator pole assembly, a rotor bearing at each end of the claw-pole rotor assembly, and a fixed excitation system which includes an excitation ring and an excitation winding, the claw-pole rotor assembly comprising an integral pole core and pole carrier disc manufactured from a single piece of metal, and a stub shaft connected to the pole core at one end thereof and journalled in the respective bearing.

2. An electrical machine as claimed in claim 1, in which a further stub shaft is integrally formed with the pole core at the other end thereof and is journalled in the other bearing.

3. An electrical machine as claimed in claim 1, in which a further stub shaft is connected to the other end of the pole core and is journalled in the other bearing.

4. An electrical machine as claimed in claim 1, 2 or 3, in which at least one stub shaft is pressed into a respective recess in the pole core.

5. An electrical machine as claimed in claim 4, in which the or each stub shaft has a milled portion where it is pressed into the pole core.

6. An electrical machine as claimed in claim 1,2 or 3, in which at least one stub shaft is butt-welded to the pole core.

7. An electrical machine as claimed in claim 1,2 or 3, in which at least one stub shaft

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

Claims

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

three excitation current diodes normally being required for a three-phase generator.

Furthermore, a circuit board 25 is provided.

The circuit board 25 carries conductor paths (not illustrated in Fig. 1) which serve to connect the ends 26 of the phase winding 14 to the associated electrodes of the diodes 23.

Furthermore, the circuit board 25 carries a spring contact 27 which, when the generator is in its assembled state, is in contact with a corresponding spring contact 28 of the voltage regulator 24 and thus establishes an electrical connection between the voltage regulator 24 and the circuit board 25. The ends 31 of the excitation winding 16 are connected to associated contacts on the circuit board 25, and thus to the spring contact 27.

Figs. 2 and 3 illustrate one embodiment of the present invention. Fig. 2 shows a unit comprising the pole core 18 and the pole carrier disc 20 which has been manufactured from a blank 32 by any suitable means such as drop-forging. Recesses 34 and 35 have at the same time been formed along the axis 33.

A first of the recesses 34 has a larger diameter for a stub shaft at the drive end, and a second of the recesses 35 has a smaller diameter for a stub shaft at the end remote from the drive end.

Fig. 3 shows the next step, namely the insertion of the stub shafts. A first stub shaft 36 is inserted into the first recess 34, and a second stub shaft 37 is inserted into the second recess 35. In the embodiment shown in Fig. 3, the two stub shafts 36,37 are provided with milled portions 38, 39. Alternatively, however, other mechanical connection means may be used. By way of example, the stub shafts may be connected to the core by butt-welding, by friction welding, by electric welding or by shrink-fitting.

The claw-pole rotor assembly comprising the core 18, the carrier disc 20 and the stub shafts 36, 37, together with two claw-pole rings as shown in Fig. 1, is then journalled by the stub shafts in rotor bearings at opposite ends of the rotor.

Fig. 4 first shows a further possibility of securing the first stub shaft 36 in the first recess 34. The first stub shaft 36 has a bore 41 in line with its axis 33. A taper plug 42 is additionally provided. Upon pressing the first stub shaft 36 into the first recess 34, the taper plug 42 is pressed into the bore 41 and widens the end of the first stub shaft 36.

Thus, the first stub shaft 36 is securely connected to the pole core 18 in the first recess 34.

However, Fig. 4 also shows a further embodiment of the invention. By suitable deforming measures, the first recess 34 is formed at one end of the blank 32 in line with the axis 33, and a stub shaft 43 is integrally formed with the pole core 18 at the other end. The stub shaft 43 replaces the second stub shaft 37 of the embodiment of Fig. 3.

Fig. 5 shows the assembly comprising the pole core 18, the pole carrier disc 20 and the pole rings 19 and 21. The pole rings 19 and 21 are interconnected by means of nonmagnetic intermediate members 44, and the assembly comprising the pole rings 19, 21, interconnected in this manner, is pressed onto the pole carrier disc 20 and is secured thereto by means of a welded joint 45.

In the complete specification of our copending patent application No. 44749/76 (Serial No. 1560747) we have claimed a slipringless electrical machine comprising a stator pole assembly, a claw-pole rotor assembly rotatable within the stator pole assembly, and a fixed excitation system including an excitation winding, the clawpole rotor assembly having a pole disc, a first pole ring mechanically and magnetically connected to the pole disc, and a second pole ring which is only mechanically connected to the first pole ring, the fixed excitation system co-operating at least indirectly with the pole disc and with the second pole ring, each pole ring comprising a plurality of claws and bridge portions between the claws, at least one of the pole rings being formed from a strip.

WHAT WE CLAIM IS:1. A slipringless electrical machine comprising a stator pole assembly, a claw-pole rotor assembly rotatable within the stator pole assembly, a rotor bearing at each end of the claw-pole rotor assembly, and a fixed excitation system which includes an excitation ring and an excitation winding, the claw-pole rotor assembly comprising an integral pole core and pole carrier disc manufactured from a single piece of metal, and a stub shaft connected to the pole core at one end thereof and journalled in the respective bearing.
2. An electrical machine as claimed in claim 1, in which a further stub shaft is integrally formed with the pole core at the other end thereof and is journalled in the other bearing.
3. An electrical machine as claimed in claim 1, in which a further stub shaft is connected to the other end of the pole core and is journalled in the other bearing.
4. An electrical machine as claimed in claim 1, 2 or 3, in which at least one stub shaft is pressed into a respective recess in the pole core.
5. An electrical machine as claimed in claim 4, in which the or each stub shaft has a milled portion where it is pressed into the pole core.
6. An electrical machine as claimed in claim 1,2 or 3, in which at least one stub shaft is butt-welded to the pole core.
7. An electrical machine as claimed in claim 1,2 or 3, in which at least one stub shaft

is secured in a recess in the pole core by means of a taper plug.
8. An electrical machine as claimed in any preceding claim which is an alternator.
9. An electrical machine as claimed in claim 8 which is a three phase alternator.
10. An electrical machine having a claw-pole rotor assembly constructed and arranged and adapted to operate substantially as hereinbefore particularly described with reference to Figs. 2 and 3 of the accompanying drawings.
11. An electrical machine having a clawpole rotor assembly constructed and arranged and adapted to operate substantially as hereinbefore particularly described with reference to Figs. 4 and 5 of the accompanying drawings.