FIELD OF INVENTION:
The present invention is generally related to the electrical machines. More particularly, the invention relates to the vertically mounted electrical machines and the bearing system utilized in it.
BACKGROUND OF THE INVENTION:
The bearing system in the vertical motor is more complex compared to the bearing system in the horizontal motor because the axial loading is more and radial loading is less in the case of vertical motor whereas the axial loading is less and radial loading is more in the case of horizontal motors. The bearing system in the vertical motor is the major reason for the failure of a vertical motor' In an IEEE paper, "Understanding vertical bearing systems and minimizing their failures", many methods are suggested in order to select a proper thrust bearing for overcoming the thrust loading in the vertical motor there by minimizing the failure of the bearing.
The failure of the vertical motors is usually because of failure in the bearing system utilized in the motors as the bearing system in vertical motor is more complex than that in horizontal motor. The thrust bearings which are capable of handling axial loading to the maximum extent and radial loading to the small extent are used in vertical motors. The higher the thrust load the more will be the complexity present in the selection of bearing system and the more will be the risk of reduction of life time of bearing system. The thrust bearing life can be extended by choosing a large size than the required but it will result

in more cost, more power to drive and less efficiency. Most of the vertical motors designed so far are based on radial flux technology and hence different types of large size thrust bearings are being utilized to overcome the different types of thrust loading. As a result, the size of the vertical motor is motor and the bearing system utilized is complicated. Using axial flux technology, an approach to reduce the size of the thrust bearing is proposed by reducing the thrust loading that also results in the compactness of the vertical motor as the axial flux technology is used and the size of the bearing system is reduced.
Most of the vertical motors designed so far are based on radial flux technology and hence different types of large size thrust bearings are being utilized to overcome the different types of thrust loading. As a result, the size of the vertical motor is more and the bearing system utilized is complicated. Though the axial flux permanent magnet motors exist in many applications including pump applications, the reduction of the size of the thrust bearing by using axial flux technology is not exploited and addressed. Using axial flux technology, an approach to reduce the size of the thrust bearing is proposed by reducing the thrust loading which also results in the compactness of the vertical motor as the axial flux technology is used and the size of the bearing system is reduced.
OBJECTS OF THE INVENTION;
It is therefore an object of the invention to reduce the size of the thrust bearing
in the vertical motor.
Another object of the invention is to make the vertical motor compact.
Yet another object of the invention is to reduce the size of the thrust bearing by using axial flux technology.

A still further object of the invention is to reduce the size of the thrust bearing by reducing the thrust loading.
SUMMARY OF THE INVENTION;
According to an aspect of the invention, an approach for reducing the size of the thrust bearing in the vertical motor is proposed by reducing the thrust loading.
The vertical motor is significant in that it is based on axial flux permanent magnet technology with a single sided structure wherein the permanent magnets are glued to the rotor part.
The vertical motor is also significant in that the rotor body of the motor is arranged downside and the stator body of the motor is arranged upside wherein the stator body of the motor is fitted to the stator frame while the rotor body of the motor is fitted over the shaft.
The air gap between the rotor and stator parts of the vertical axial flux permanent magnet motor (VAFPMM) is kept as small as possible in order to reduce the thrust loading to the maximum extent.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Fig. 1 shows a sectional view of the vertical motor utilizing radial flux
technology.
Fig. 2 shows a sectional view of the single sided structure of axial flux permanent magnet motor.

Fig. 3 is a sectional view of the double sided structure of axial flux permanent magnet motor.
Fig. 4 is a sectional view of the vertical motor utilizing axial flux permanent technology with a single sided structure, rotor part being downside and stator part being upside.
DETAILED DESCRIPTION OF A PREFFERED EMBODIMENT OF THE INVENTION
A vertical motor based on radial flux technology as shown in Fig. 1 has the total downward thrust equal to the weight (19) of the components like rotor, shaft etc., additional to the external loading. So a large size thrust bearing is to be provided in spite of high cost for overcoming downward thrust loading, or the risk of failure of the thrust bearing increases and the life time of the bearing reduces. The axial flux permanent magnet (23) motor in any application generally uses a double sided structure in order to nullify the magnetic force of attraction over the stator and rotor components of the motor which otherwise exists in the single sided structure and creates a loading in the axial direction. Since the rotor body of the motor is mounted over the shaft (12) of the motor, the magnetic force of attraction over the rotor body will make both the rotor and the shaft (12) together to experience the axial loading.
The axial loading is present only in one direction in the single sided structure of axial flux permanent magnet motor as shown in Fig. 2. The axial loading is present along both the directions in the double sided structure of axial flux permanent magnet motor as shown in Fig. 3 and thus there is no net axial loading over the shaft (12) because of equal amount of axial loading in both the directions provided the rotor core (24) sizes and magnet sizes are same.

An approach for reducing the size of the thrust bearing in the vertical motor is done by reducing the thrust loading acting downwards. The vertical motor is designed based on axial flux permanent magnet technology with a single sided structure in which the rotor part of the motor is arranged downside and the stator part of the motor is arranged upside as shown in Fig. 4. Permanent magnets are glued to the rotor part of the vertical axial flux permanent magnet motor (VAFPMM) in order to exploit their advantages like compactness, high magnetic flux density in the air gap (16) of the motor etc., The VAFPMM is significant in that the magnetic force of attraction over the rotor body and the shaft (12) now acts in the upward direction and reduces the thrust loading in the downward direction. Thus the total downward thrust in VAFPMM is equal to the weight (19) of few components plus the external loading minus the magnetic force as shown in Fig. 4.
In an axial flux permanent magnet machine, the force of attraction between the
rotor and stator parts depend on the strength of the air gap (16) flux density
which depends on many parameters like air gap (16), the grade of materials
used in the machine etc., The relation between the air gap (16) and the
magnetic flux density in the air gap (16) is that the magnetic flux density in the
air gap (16) increases while the air gap of the machine, reduces. Thus the
smaller the air gap (16) of the machine, the more will be the force of attraction
between the stator and rotor parts of the machine. Hence, the air gap (16)
between the rotor and stator parts of the vertical axial flux permanent magnet
motor (VAFPMM) is kept as small as possible in order to increase the magnetic:
force of attraction thereby to reduce the thrust loading to the maximum extent.
In order to overcome very high thrust loading, the selection of very high energy rare earth permanent magnet materials and utilization of soft magnetic material for manufacture of stator core (21) can further increase the air gap

(16) magnetic flux density leading to high magnetic force of attraction between the rotor and stator parts of the VAFPMM. Addition of more single sided structures in tandem in the VAFPMM can also overcome high thrust loading in the motor.
An approach for reducing the thrust loading in the downward direction in the vertical motor is proposed by increasing the magnetic force of attraction in the VAFPMM in the upward direction. So the size of the thrust bearing reduces the bearing system in the VAFPMM. This also results in the compactness of the VAFPMM as the axial flux technology is utilized and the size of the bearing is reduced.

WE CLAIM;
1. A vertical permanent magnet motor (VPMM) based on axial technology of a single sided structure, using reduced size of thrust bearing,
comprising:
- a shaft (42) disposed within the magnetic frame encompassed by the said thrust bearing at one end and lower guide bearing (44) at other end characterized in that;
- a rotor which includes the permanent magnet is placed below a stator along the shaft (42) such that magnetic force of attraction over the rotor body and shaft (42) acts in the upward direction.

2. A vertical permanent magnet motor as claimed in claim 1, wherein the rotor structured may be surface mounted type rotor structure or insertion type rotor structure.
3. A vertical permanent magnet motor as claimed in claim 1, as illustrated in the accompanying drawings.
4. A vertical permanent magnet motor as claimed in claim 1, wherein modular construction of plurality of single sided structure may be used.