GB2231207A

GB2231207A - Stator construction for a reluctance machine

Info

Publication number: GB2231207A
Application number: GB9009977A
Authority: GB
Inventors: Dieter Schieber; Siegfried Schustek; Helmut Haerer
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1989-05-03
Filing date: 1990-05-03
Publication date: 1990-11-07
Anticipated expiration: 2010-05-03
Also published as: SE9001570D0; IT1240035B; GB2231207B; IT9020199A0; IT9020199A1; SE510836C2; SE9001570L; DE3914635C1; GB9009977D0

Description

4 1 - Reluctance machine

The invention is based on a reluctance machine, particularly a reluctance motor of the generic type defined in the precharacterizing clause of Claim 1.

Such reluctance machines having an unwound rotor and high utilisation are advantageously used as hightorque servomotor for rotational drives in robot systems or as slow-running auxiliary and main drives in vehicles of all types.

In a known reluctance machine of this type (DE 38 21 660 A1) the tooth sections are constructed as laminated-core segments. the separating planes between the individual laminations extending in the axial direction of the rotor. The thickness of the laminated-core segments in the circumferential direction corresponds to the tooth width of the stator teeth. The laminated-core segments are produced individually, placed onto the associated phase winding and individually attached to the inner and outer stator, respectively, for example by insertion into pockets provided at the case or by suitable pouring-in or bonding-in. The many individual parts which, as a result, are present in the inner and outer stator make extreme demands on production accuracy in the industrial production of the reluctance machine.

Advantages of the invention The reluctance machine according to the invention, having the characterizing features of Claim 1, has the advantage of simple industrial production. Due to the structure according to the invention, the required pitch accuracy of the stator and rotor teeth can be relatively simply ensured by stamping. The air gap contours of rotor and outer and inner stator can be easily machined by grinding in the preassembled condition. Such post-processing is unavoidable because of the extremely small air gap required for reluctance machines. Inner and outer stator are of the same construction and are distinguished by a simple structure. By constructing the yoke rings of soft-magnetic compound material and by segmenting the laminated tooth rings, considerable improvement is achieved with respect to low electric losses with low magnetic voltage drops. In this connection, it is particularly advantageous if the tooth rings are assembled from segments of bakedenamel laminations abutting in the circumferential direction in accordance with a preferred embodiment of the invention.

Like the known reluctance machine, the reluctance machine according to the invention with its toroidal coils, preferably in the form of preformed coils of baked-enamel laminations, has the advantage that, with the same expenditure of copper, higher ampere-turns and thus a greater magnetic flux can be achieved compared with conventional wave or lap windings. This is due to the shorter mean conductor length of a toroidal coil compared with a wave or lap winding. The exciter winding can be wound extremely easily and simply. The required copper expenditure is much lower. Due to the lack of winding end turns of the stator winding protruding past the laminated core, an impairment of the systems for sensing the rotational rotor position by means of current fields is largely prevented.

Claims

Due to the measures listed in the further claims, advantageous further developments and improvements of the reluctance machine specified in Claim 1 are possible. Drawing The invention is explained in greater detail in the description following, with reference to an illustrative embodiment shown in the drawing,. in which, in each case diagrammatically:

1 Fig. 1 shows a section of a longitudinal section through a three-phase reluctance motorf Fig. 2 shows a section of a cross-section of the reluctance motor in Fig. 1.

Description of the illustrative embodiment The reluctance motor, a section of which is shown in longitudinal section in Fig. 1 as an example of a reluctance machine, has a hollow-cylindrical rotor 4101 which is rotationally rigidly connected via a disc 411 to the shaft 412, which is here constructed to be hollow. The shaft 412 is radially supported via a total of two rolling bearings 413 against a hub 430 which is of one piece with an end cover 431. The end cover 431 closes of f the open end of a case 414 constructed to be potshaped and carries a dome 432, which protrudes towards the outside, for accommodating sensors for sensing the rotational rotor position. The hub 430 protrudes coaxially into the case 414 close to the disc 411 of the rotor 410. Opposite to the rotor 410 with its outer and inner rotor teeth 419, 420 of a constant tooth width and tooth pitch, an outer stator 415 is located with its stator teeth 421 and an inner stator 416 with its stator teeth 422, leaving the outer air gap 417 and the inner air gap 418. The outer stator 415 is secured at the case 414 whilst the inner stator 416 is seated on the hub 413 to rotate therewith. Outer stator 415 and inner stator 416 are of identical construction and in each case provided with a three-phase stator winding 423 and 424, respectively.

Outer stator 415 and inner stator 416 are subdivided into three stator sections 415a-c and 416a-c with tooth sections 421a-c and 422a-c with tooth sections 421a-c and 422a-c. The individual stator sections 415ac and 416a-c are of identical construction and in each case consist of a yoke ring 433 of soft-magnetic compound material (WMV) and two rings 434, 435 of magnetically conductive material which are laminated in the axial direction and radially pressed onto the yoke ring 433.

Each tooth ring 434, 435 carries in the area of the air gap an associated tooth section 421a-c and 422a-c which, together, result in the stator teeth 421 and 422, respectively. The tooth sections 421a-c and 422a-c in each stator 415, 416 are offset with respect to one another in the circumferential direction. The of f set corresponds to the tooth pitch of the rotor teeth 419. 420 divided by the number of phases of the stator windings 423, 424, that is to say a third of the tooth pitch in the case of three-phase windings. Between the tooth rings 434, 435, a phase winding 423a-c and 424a-c of the stator winding 423 and 424, respectively, is in each case arranged. Each phase winding 423a-c, 424a-c is constructed as annular circular preformed coil of bakedenamel wire and is supported against the yoke ring 433 and between the two tooth rings 434 and 435. Current flows in pairs and in the same direction through the phase windings 423a-c and 424a-c so that a magnetic flux forms between outer and inner stator 415, 416 via the rotor 410, which is diagrammatically drawn dot dashed with 442 in Fig. 1.

As can be seen from Fig. 2, the yoke rings 433 are assembled of segments 439 placed against one another in the circumferential direction, which are in each case bonded to a support tube 436a-c and 437a-c, respectively. In this arrangement. the outer support tubes 436a-c are pressed into the case 414 whilst the inner support tubes 437a-c are pressed onto the hub 430. To reduce electric losses, the tooth rings 434. 435 are also assembled of segments 439 in the circumferential direction. Each tooth ring segment 439 consists of insulated baked-enamel laminations. Instead of the individual support tubes 436a-c and 437a-c for the individual stator sections 415a-c and 416a-c, respectively, a common support tube 436 can also be provided for all outer stator sections 415a-c and a uniform support tube 437 for all inner stator sections 416a-c.

The rotor 10 consists of rings 440 laminated in the axial direction, of magnetically conductive material, fl which in each case extend over the axial extent of the tooth rings 439 and are connected to one another by support members 441. The support members 441 are designed exclusively from the point of view of the least possible weight since they are without significance for the magnetic flux. Due to the construction of the rotor 410 described, the latter has a very low moment of inertia.

Claims 1. A reluctance machiner particularly a reluctance motor, having a hollow- cylindrical rotor which is laminated in the axial direction and rotates with a shaft and which carries on its outer and inner cylinder surface a number of axially extending rotor teeth which are arranged to be uniformly distributed over the circumference, and having an outer stator and an inner stator which are opposite to the outer and inner rotor teeth with an equal number of equidistant stator teeth coaxially to the rotor, leaving an outer and inner air gap, carry in each case a multi-phase stator winding of the same number of phases and are subdivided in the axial direction into a number of stator sections, in each case carrying a stator tooth section, which corresponds to the number of phases of the stator windings, the stator tooth sections in each case being displaced by the tooth pitch of the rotor teeth divided by the number of phases of the stator windings with respect to one another in the circumferential direction at the air gap, each stator section of the outer and inner stator accommodating a phase winding of the associated multi-phase stator winding, which passes through it in the form of a toroldal coil in the circumferential direction, and current flowing alternately in pairs and in the same direction through the phase windings in the stator sections of outer and inner stator, characterized in that each stator section (415a-c, 416a-c) exhibits a yoke ring (433) of segments (438) of soft- magnetic compound material (WMF). which are placed against one another in the circumferential direction. on which yoke ring two rings (434. 435) of magnetically conductive material. which are arranged at an axial distance from one another and which carry the stator tooth sections (421a-cj 422a-c)r are radially pressed-on and are laminated in the axial direction, and in that one phase winding (423a-c) is arranged between the tooth rings (434, 435).

2. Machine according to Claim 1, characterized in that the tooth rings (434, 435) are assembled from segments (439) abutting in the circumferential direction.

3. Machine according to Claim 2, characterized in that the tooth ring segments (439) consist of insulated baked-enamel laminations.

4. Machine according to one of Claims 1 - 3, characterized in that the phase windings (423a-c, 424a-c) of each stator section (415a-c, 416a-c) are supported at the yoke ring (433) and at the two tooth rings (434, 435).

5. Machine according to Claim 4, characterized in that each phase winding (423a-c, 424a-c) is constructed as preformed coil of baked-enamel wire.

6. Machine according to one of Claims 1-5,, characterized in that the yoke rings (433) of the stator sections (415a-c and 416a-c) forming the outer and inner stator (415 and 416), respectively, are in each case bonded to a support tube (436a-c and 437a-c).

7. Machine according to Claim 6r characterized in that the support tubes (436a-c) of the outer stator (415) are in each case pressed onto the inner wall of a potshaped case (414) and the support tubes (437a-c) of the inner stator (416) are in each case pressed onto a hub (430) coaxially arranged in the case (414) and in that the hub (430) is secured at an end cover (431) closing the open end of the case (414).

8. Machine according to Claim 7, characterized in that the rotor (410) is secured at a disc (411) and in that the disc (411) is connected to rotate with a preferably hollow shaft (412) which is coaxially arranged in the interior of the hub (430) and is supported at the latter via radial bearings (413).

9. Machine according to Claim 7 or 8, characterized in that the end cover (431) exhibits a dome (432) protruding towards the outside.

10. Machine according to one of Claims 1 - 9, characterized in that the rotor (410) is assembled from rings (440) of magnetically conductive material, laminated in the axial direction, which extend over the axial extent of the tooth rings (434, 435) of the stator sections (415a-c, 416ac), and intermediate low-weight support members (441), which extend over the axial extent of the phase windings (423a-c, 424a-c).

11. A reluctance machine substantially as herein described with reference to the accompanying drawings.

Published 1990 atThe Patent Office, State House. 6671 HigI, Holborn, London WC1R 4TP- Further copies maybe obtainedfrom The Patent OfficeSales Branch. St Mary Cray, Orpington. Kent BR5 3RD. Printed by Multiplex techniques ltd. St Mary Cray. Kent. Con. D87