GB2066584A - Electric motors - Google Patents

Abstract

An electric motor includes a rotor (6) and a rotor shaft (12). The shaft carries a fan wheel or impeller (13) for producing a reduced air pressure or a raised air pressure, the end of the shaft nearest the fan wheel or impeller having a bearing (2), which bearing, by its construction, requires an axial force to be acting thereon in use of the motor. This axial force is provided by the fan wheel or impeller which, in the case of operation to produce a reduced air pressure, has a tendency to draw the rotor shaft towards the bearing thereby providing the axial adjusting force for the bearing (2). The motor may form part of a suction cleaner and can be mounted in a motor chamber (8) whilst the fan wheel or impeller is mounted in a suction chamber (9). <IMAGE>

Description

SPECIFICATION Improvements in or relating to electric motors This invention relates to an electric motor including a rotor, a rotor shaft and a mounting therefor, the rotor shaft carrying a fan wheel or impeller for producing a reduced air pressure or a raised air pressure.

Such mountings are known which have bearings which require an axial adjusting or setting force in order to ensure satisfactory functioning. These are bearings such as, for example, flanged contact bearings, ball cup bearings or angular contact ball bearings. With these constructions, axial setting forces are applied to the bearings by additional structural elements, such as springs, balls or other separate parts.

According to one aspect of the present invention, there is provided an electric motor including a rotor, a rotor shaft and a mounting therefor, the rotor shaft carrying a fan wheel or impeller for producing a reduced air pressure or a raised air pressure, and there being a bearing on the rotor shaft at its end nearest said fan wheel or impeller, which bearing, by its construction, requires an axial adjusting force in use, said force being arranged to be provided by said fan wheel or impeller in use of said motor.

According to another aspect of the present invention, there is provided a suction cleaner incorporating an electric motor which is essentially as just defined.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawing, in which the single figure is a schematic longitudinal sectional view of part of a suction cleaner housing.

The part of the suction cleaner housing shown includes a motor chamber 8 and a suction chamber 9 separated by a partition 11. An electric motor 10 is arranged in the motor chamber 8 and is fixed on the partition 1 A drive shaft 12 is mounted on a rotor 6 of the motor 10 and extends into the suction chamber 9 and carries therein a fan wheel or impeller 13.

A bearing 2 is arranged on the rotor shaft 6 at its end nearest the fan wheel or impeller 13. The bearing 2, as a result of its construction, always normally requires an axial setting force in use. In the example shown, the bearing 2 is a so-called angular contact ball bearing, which consists of an outer race 14, an inner race 15 and balls 16, these parts being so assembled that the ball bearing can be taken apart in the direction opposite to the direction of the arrow. A slide or plain bearing 5 is arranged on the opposite end of the rotor shaft 6 and comprises a felt ring 17, a clamping plate 18, a cover 19 and a check plate 20.

In operation, a reduced air pressure is established in the suction chamber 9 by the fan wheel or impeller 13. An air outlet opening (not shown) of the suction chamber 9 is situated behind the fan wheel or impeller 13 (as viewed in the drawing).

With the motor 10 operating, the reduced pressure in the suction chamber 9 causes an axial force in a direction which is indicated by the arrow. As a result, the inner race 15 is urged towards and exerts a pressure on the outer race 14 via the balls 16. Thus, no separate device is required to apply an axial setting force on the bearing 2.

In the event of the direction of the force on the bearing 2 due to weight being identical with the arrow, the weight of the rotor 6 will hold the angular contact ball bearing 2 together when the motor 10 is not operating.

With "overhead operation", that is, when the direction of the force due to the weight of the rotor 6 is directed opposite to the arrow so that there is a tendency for it to hang from the bearing 2, the check plate 20 causes the rotor 6 to bear against the plain bearing 5 when the motor 10 is not operating. When the motor is operating in such a case, it is however important that the axial force produced by the reduced air pressure caused by movement of the fan wheel or impeller 13 is greater than the force due to the weight of the rotor 6 to enable the required axial setting force to act on the bearing 2.

It will be appreciated that the required axial force would also be produced in an alternative form of construction in which the fan wheel or impeller is arranged to provide a raised air pressure.

1. An electric motor including a rotor, a rotor shaft and a mounting therefor, the rotor shaft carrying a fan wheel or impeller for producing a reduced air pressure or a raised air pressure, and there being a bearing on the rotor shaft at its end nearest said fan wheel or impeller, which bearing, by its construction, requires an axial adjusting force in use, said force being arranged to be provided by said fan wheel or impeller in use of said motor.

2. A motor as claimed in claim 1, wherein said bearing is an angular contact ball bearing.

3. A motor as claimed in claim 1 or 2, wherein a sliding or plain bearing is provided on said rotor shaft at its opposite end.

4. A motor as claimed in claim 1, 2 or 3, wherein said rotor is arranged so that it has a tendency to hang from the first mentioned bearing, the axial force produced in use by said fan wheel or impeller being greater than the force due to the weight of the rotor in order to provide said axial adjusting force.

5. A motor as claimed in claims 3 and 4, wherein a check plate is provided on said sliding or plain bearing in order for said rotor to be supported.

6. An electric motor, substantially as hereinbefore described with reference to the accompanying drawing.

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

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in or relating to electric motors This invention relates to an electric motor including a rotor, a rotor shaft and a mounting therefor, the rotor shaft carrying a fan wheel or impeller for producing a reduced air pressure or a raised air pressure. Such mountings are known which have bearings which require an axial adjusting or setting force in order to ensure satisfactory functioning. These are bearings such as, for example, flanged contact bearings, ball cup bearings or angular contact ball bearings. With these constructions, axial setting forces are applied to the bearings by additional structural elements, such as springs, balls or other separate parts. According to one aspect of the present invention, there is provided an electric motor including a rotor, a rotor shaft and a mounting therefor, the rotor shaft carrying a fan wheel or impeller for producing a reduced air pressure or a raised air pressure, and there being a bearing on the rotor shaft at its end nearest said fan wheel or impeller, which bearing, by its construction, requires an axial adjusting force in use, said force being arranged to be provided by said fan wheel or impeller in use of said motor. According to another aspect of the present invention, there is provided a suction cleaner incorporating an electric motor which is essentially as just defined. For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawing, in which the single figure is a schematic longitudinal sectional view of part of a suction cleaner housing. The part of the suction cleaner housing shown includes a motor chamber 8 and a suction chamber 9 separated by a partition 11. An electric motor 10 is arranged in the motor chamber 8 and is fixed on the partition 1 A drive shaft 12 is mounted on a rotor 6 of the motor 10 and extends into the suction chamber 9 and carries therein a fan wheel or impeller 13. A bearing 2 is arranged on the rotor shaft 6 at its end nearest the fan wheel or impeller 13. The bearing 2, as a result of its construction, always normally requires an axial setting force in use. In the example shown, the bearing 2 is a so-called angular contact ball bearing, which consists of an outer race 14, an inner race 15 and balls 16, these parts being so assembled that the ball bearing can be taken apart in the direction opposite to the direction of the arrow. A slide or plain bearing 5 is arranged on the opposite end of the rotor shaft 6 and comprises a felt ring 17, a clamping plate 18, a cover 19 and a check plate 20. In operation, a reduced air pressure is established in the suction chamber 9 by the fan wheel or impeller 13. An air outlet opening (not shown) of the suction chamber 9 is situated behind the fan wheel or impeller 13 (as viewed in the drawing). With the motor 10 operating, the reduced pressure in the suction chamber 9 causes an axial force in a direction which is indicated by the arrow. As a result, the inner race 15 is urged towards and exerts a pressure on the outer race 14 via the balls 16. Thus, no separate device is required to apply an axial setting force on the bearing 2. In the event of the direction of the force on the bearing 2 due to weight being identical with the arrow, the weight of the rotor 6 will hold the angular contact ball bearing 2 together when the motor 10 is not operating. With "overhead operation", that is, when the direction of the force due to the weight of the rotor 6 is directed opposite to the arrow so that there is a tendency for it to hang from the bearing 2, the check plate 20 causes the rotor 6 to bear against the plain bearing 5 when the motor 10 is not operating. When the motor is operating in such a case, it is however important that the axial force produced by the reduced air pressure caused by movement of the fan wheel or impeller 13 is greater than the force due to the weight of the rotor 6 to enable the required axial setting force to act on the bearing 2. It will be appreciated that the required axial force would also be produced in an alternative form of construction in which the fan wheel or impeller is arranged to provide a raised air pressure. CLAIMS

1. An electric motor including a rotor, a rotor shaft and a mounting therefor, the rotor shaft carrying a fan wheel or impeller for producing a reduced air pressure or a raised air pressure, and there being a bearing on the rotor shaft at its end nearest said fan wheel or impeller, which bearing, by its construction, requires an axial adjusting force in use, said force being arranged to be provided by said fan wheel or impeller in use of said motor.

2. A motor as claimed in claim 1, wherein said bearing is an angular contact ball bearing.

3. A motor as claimed in claim 1 or 2, wherein a sliding or plain bearing is provided on said rotor shaft at its opposite end.

4. A motor as claimed in claim 1, 2 or 3, wherein said rotor is arranged so that it has a tendency to hang from the first mentioned bearing, the axial force produced in use by said fan wheel or impeller being greater than the force due to the weight of the rotor in order to provide said axial adjusting force.

5. A motor as claimed in claims 3 and 4, wherein a check plate is provided on said sliding or plain bearing in order for said rotor to be supported.

6. An electric motor, substantially as hereinbefore described with reference to the accompanying drawing.

7. A suction cleaner incorporating an electric motor as claimed in any one of the preceding claims.

8. A suction cleaner as claimed in claim 7, substantially as hereinbefore described with reference to the accompanying drawing.