GB1572619A

GB1572619A - Electric motor

Info

Publication number: GB1572619A
Application number: GB43286/77A
Authority: GB
Original assignee: SKF Kugellagerfabriken GmbH
Current assignee: SKF GmbH
Priority date: 1976-10-19
Filing date: 1977-10-18
Publication date: 1980-07-30
Also published as: FR2368818A1; DE2647031A1; IT1113649B

Description

(54) ELECTRIC MOTOR (71) We, SKF KUGELLAGERFABRIKEN GESELLSCHAFT MIT BESCHRANKTER HAF TUNG, a German Body Corporate, of Ernst Sachs-Strasse 2-8 8720 Schweinfurt 2, German Federal Republic, 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 a method of assembling an electric motor and to an electric motor so assembled.

The invention provides a method of assembling an electric motor comprising providing a stator having a bore, a bearing carrier for attachment to the stator and having a bore, in which to carry a bearing, and a shaft on which is mounted a rotor and a bearing, inserting the shaft with the rotor and the bearing axially into the bore of the stator until co-operating surfaces with rotor and in the bore of the stator engage each other and centre the rotor with respect to the stator, then centring the bearing carrier with the bearing in the bore of the carrier, then attaching the centred bearing carrier to the stator, then moving the shaft with the rotor and the bearing axially until the co-operating surfaces disengage and then locating the rotor for rotation in the bore of the stator.

In an electric motor assembled according to the invention the rotor may be cylindrical and the stator may have a correspondingly cylindrical bore, the stator of the rotor may have an annular element projecting radially towards a circumferentially extending recess in the rotor or the stator, the diameter of the surface of the element facing the recess being the same as the diameter of the outer surface of the rotor or the bore of the stator, and the axial width of the recess being greater than the axial width of the element There may be two elements and a recess for each element, the axial distance between the centres of the recesses being the same as the axial distance between the centres of the elements.

The rotor may be conical and the stator may have a correspondingly conical bore.

The shaft may have a shoulder between the rotor and the bearing, the bearing being located around the neck of the shaft, and one or more shims may be located between the bearing and the shoulder. The bearing may be located axially in the bore of the bearing carrier by integral abutments of that bore.

Two embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, of which: Figure 1 is an axial section of an electric motor having a cylindrical rotor and a correspondingly cylindrical bore in the stator and which is being assembled; Figure 2 is an axial section of the eleotric motor of Figure 1 when assembled; Figure 3 is an axial section of an electric motor having a conical rotor and a correspondingly conical bore in the stator and which is being assembled; and Figure 4 is an axial section of the electric motor of Figure 3 when assembled.

The electric motor shown in Figures 1 and 2 comprises a stator 1 having a cylindrical bore 8, a cylindrical rotor 2 mounted on a shaft 3, two bearings, 5 and 6, mounted on the shaft one on each side of the rotor, and two bearing carriers 4, one for each bearing and each having a bore 12 to carry the respective bearings. On each side with the rotor 2 is a disc 7 of a greater diameter than the rotor and thus forming an annular element projecting radially outwardly. In the bore 8 of the stator are two circumferentially extending recesses 9. The diameter of each of the recesses 9 is greater than the diameter of each of the discs 7 and the axial width of each of the recesses is greater than the axial width of each of the discs. The axial distance m between the centres of the recesses 9 is the same as the axial distance between the centres of the discs 7. The outside diameter of each disc 7 is the same as the dia~ the bore 8 of the stator 1, and theousie diameter of the rotor 2 is less than the diameter of the bore 8.

The shaft 3, with the rotor 2 and bearings 5 and 6, is inserted axially into the bore 8 of the stator 1 until co-operating surfaces comprising the surface of the bore 8 and the outer surface of each of the discs 7 engage and centre the rotor with respect to the stator. This is the position shown in Figure 1 with the rotor 2 centred and there being an annular air gap of radial dimension s between the rotor and the stator 1. The shaft 3 can have been inserted from the left or the right of the drawing. Once the rotor 2 has been centred, each bearing carrier 4 is centred with the respective bearing, S or 6, in the bore 12 of the carrier, and is then attached or rigidly secured to the stator 1 by, for example, screws or an adhesive. Then the shaft 3 with the rotor 2 and bearings 5 and 6 is moved to the left until the co-operating surfaces disengage and the rotor is free to rotate and the discs 7 intend towards the recesses 9. This is the position shown in Figure 2. In the embodiment described the bore 12 of the right hand bearing carrier 4 has an integral abutment 10 so that shaft 3 is moved to the left until the bearing 5 abuts the abutment 10. The bearing 5 is then located axially by a second abutment 11 being formed in the bore 12.

Instead of annular elements being formed by the discs 7 with rotor 2, and. the recesses being formed in the bore 8 of the stator 1, the arrangement may be the reverse: annular elements being located in the bore 8 and corresponding recesses being formed. in the rotor 2. Possibly, instead of two annular elements and two recesses, there may be one of each arranged centrally.

The electric motor shown in Figures 3 and 4 has a conical rotor 14 and a stator 16 with a correspondingly conical bore 15.

The shaft 3, with the rotor 14 and bearings 5 and 6, is inserted from the left of the drawing into the bore 15 of the stator 16 until co-operating surfaces comprising outside surface 13 of the rotor and the surface of the bore 15 engage each other and centre the rotor with respect to the stator. The bearing carriers 4, each with a respective one of the bearings 5 and 6 in its bore 12, are centred and then attached to the stator 16.

The shaft 3, with the rotor 14 and bearings 5 and 6, is then moved to the left until the co-operating surfaces disengage and the bearing 5 is located axially by means of integral abutments 10 and 11 in bore 12 of respective bearing carrier 4.

Each of the bearings 5 and 6 in both em bodiments described is located around a neck of the shaft 3 with the shoulder lying be tween each bearing and the rotor, 2 or 14.

embodiment described with reference o igures 3 and 4, the air gap s between the rotor surface 13 and the bore 15 may be varied by inserting or removing shims 17 between the bearing 5 and the shoulder on the shaft 3.

In the embodiments described the bearings 5 and 6 may be rolling bearings or plain bearings. Also the shaft 3 may be mounted in only one bearing carried in one carrier.

WHAT WE CLAIM IS: 1. A method of assembling an electric motor comprising providing a stator having a bore a bearing carrier for attachment to the stator and having a bore in which to carry a bearing, and a shaft on which is mounted a rotor and a bearing, inserting the shaft with the rotor and the bearing axially into the bore of the stator until co-operating surfaces with the rotor and in the bore of the stator engage each other and centre the rotor with respect to the stator, then centring the bearing carrier with the bearing in the bore of the carrier, then attaching the centred bearing carrier to the stator, then moving the shaft with the rotor and. the bearing axially until the co-operating surfaces disengage and then locating the rotor for rotation in the bore of the stator.

2. A method of assembling an electric motor substantially as herein described with reference to Figures 1 and 2 or with reference to Figures 3 and 4 of the accompanying drawings.

3. An electric motor assembled by a method as claimed in claim 1 or 2 wherein the rotor is cylindrical and the stator has a correspondingly cylindrical bore, the stator or the rotor has an annular element projecting radially towards a circumferentially extending recess in the rotor or the stator, the diameter of the surface of the element facing the recess being the same as the diameter of the outer surface of the rotor or the bore of the stator, and the axial width of the recess being greater than the axial width of the element.

4. An electric motor as claimed in claim 3 wherein there are two annular elements and a recess for each element, the axial distance between the centres of the recesses being the same as the axial distance between the centres of the elements.

5. An electric motor assembled by a method as claimed in claim 1 or 2 wherein the rotor is conical and the stator has a correspondingly conical bore.

6. An electric motor as claimed in claims 3, 4 or 5 wherein the shaft has a shoulder

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

Claims

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

the recesses is greater than the axial width of each of the discs. The axial distance m between the centres of the recesses 9 is the same as the axial distance between the centres of the discs 7. The outside diameter of each disc 7 is the same as the dia~ the bore 8 of the stator 1, and theousie diameter of the rotor 2 is less than the diameter of the bore 8.

The shaft 3, with the rotor 2 and bearings 5 and 6, is inserted axially into the bore 8 of the stator 1 until co-operating surfaces comprising the surface of the bore 8 and the outer surface of each of the discs 7 engage and centre the rotor with respect to the stator. This is the position shown in Figure 1 with the rotor 2 centred and there being an annular air gap of radial dimension s between the rotor and the stator 1. The shaft 3 can have been inserted from the left or the right of the drawing. Once the rotor 2 has been centred, each bearing carrier 4 is centred with the respective bearing, S or 6, in the bore 12 of the carrier, and is then attached or rigidly secured to the stator 1 by, for example, screws or an adhesive. Then the shaft 3 with the rotor 2 and bearings 5 and 6 is moved to the left until the co-operating surfaces disengage and the rotor is free to rotate and the discs 7 intend towards the recesses 9. This is the position shown in Figure 2. In the embodiment described the bore 12 of the right hand bearing carrier 4 has an integral abutment 10 so that shaft 3 is moved to the left until the bearing 5 abuts the abutment 10. The bearing 5 is then located axially by a second abutment 11 being formed in the bore 12.

Instead of annular elements being formed by the discs 7 with rotor 2, and. the recesses being formed in the bore 8 of the stator 1, the arrangement may be the reverse: annular elements being located in the bore 8 and corresponding recesses being formed. in the rotor 2. Possibly, instead of two annular elements and two recesses, there may be one of each arranged centrally.

The electric motor shown in Figures 3 and 4 has a conical rotor 14 and a stator

16 with a correspondingly conical bore 15.

The shaft 3, with the rotor 14 and bearings 5 and 6, is inserted from the left of the drawing into the bore 15 of the stator 16 until co-operating surfaces comprising outside surface 13 of the rotor and the surface of the bore 15 engage each other and centre the rotor with respect to the stator. The bearing carriers 4, each with a respective one of the bearings 5 and 6 in its bore 12, are centred and then attached to the stator 16.

The shaft 3, with the rotor 14 and bearings 5 and 6, is then moved to the left until the co-operating surfaces disengage and the bearing 5 is located axially by means of integral abutments 10 and 11 in bore 12 of respective bearing carrier 4.

Each of the bearings 5 and 6 in both em bodiments described is located around a neck of the shaft 3 with the shoulder lying be tween each bearing and the rotor, 2 or 14.

embodiment described with reference o igures 3 and 4, the air gap s between the rotor surface 13 and the bore 15 may be varied by inserting or removing shims 17 between the bearing 5 and the shoulder on the shaft 3.

In the embodiments described the bearings 5 and 6 may be rolling bearings or plain bearings. Also the shaft 3 may be mounted in only one bearing carried in one carrier.

WHAT WE CLAIM IS: 1. A method of assembling an electric motor comprising providing a stator having a bore a bearing carrier for attachment to the stator and having a bore in which to carry a bearing, and a shaft on which is mounted a rotor and a bearing, inserting the shaft with the rotor and the bearing axially into the bore of the stator until co-operating surfaces with the rotor and in the bore of the stator engage each other and centre the rotor with respect to the stator, then centring the bearing carrier with the bearing in the bore of the carrier, then attaching the centred bearing carrier to the stator, then moving the shaft with the rotor and. the bearing axially until the co-operating surfaces disengage and then locating the rotor for rotation in the bore of the stator.
2. A method of assembling an electric motor substantially as herein described with reference to Figures 1 and 2 or with reference to Figures 3 and 4 of the accompanying drawings.
3. An electric motor assembled by a method as claimed in claim 1 or 2 wherein the rotor is cylindrical and the stator has a correspondingly cylindrical bore, the stator or the rotor has an annular element projecting radially towards a circumferentially extending recess in the rotor or the stator, the diameter of the surface of the element facing the recess being the same as the diameter of the outer surface of the rotor or the bore of the stator, and the axial width of the recess being greater than the axial width of the element.
4. An electric motor as claimed in claim 3 wherein there are two annular elements and a recess for each element, the axial distance between the centres of the recesses being the same as the axial distance between the centres of the elements.
5. An electric motor assembled by a method as claimed in claim 1 or 2 wherein the rotor is conical and the stator has a correspondingly conical bore.
6. An electric motor as claimed in claims 3, 4 or 5 wherein the shaft has a shoulder

between the rotor and the bearing, the bearing being located around the neck of the shaft, and one or more shims are located between the bearing and the shoulder.
7. An electric motor as claimed in any one of claims 3 to 6 wherein the bearing is located axially in the bore of the bearing carrier by integral abutments of that bore.
8. An electric motor assembled by a method as claimed in claim 1 or 2 and sub stantiaffly as herein described with reference to and as shown in Figure 2 or with reference to and as shown in Figure 4 of the accompanying drawings.