Claims:WE CLAIM:

1. Twin flow cooling device for ventilating compact induction motors comprising a twin curved ducts (1,2) integrated to each other, each of which is connected to a flap (3, 4) constituting an assembly, which is secured to rotor/partition flange.

2. Twin flow cooling device for ventilating compact induction motors as claimed in claim 1, wherein the twin duct assembly acts as a fan due to centrifugal action which is arranged radially on to the rotor collar or rotor clamping plate, in which the inner and outer radii ends are kept open to draw in and discharge out air.

3. Twin flow cooling device for ventilating compact induction motors as claimed in claim 1 or 2, wherein air flow takes place in two streams, wherein first stream coming out of the inner duct is directed into the stator/ rotor air gap and stator end winding and the second stream emerging out of the second duct directs the air to cool the back of core.

4. Twin flow cooling device for ventilating compact induction motors as claimed in the claims 1-3, wherein the structure of the twin curved duct is preferably made of non-metallic structural glass, which is composite fibre glass.

5. Twin flow cooling device for ventilating compact induction motors as claimed in the claims 1-4, wherein the curved double ducts take the air smoothly on to the winding structural glass due to the construction of the ducting air is blown out of the ducts due to centrifugal action, in which the blown air cools the stator end winding and flows back to the front side of the motor, wherein the head created by the duct arrangement due to centrifugal action enables the flow to take place, wherein the fan has an inner ring over which the composite material is built, so that the invention enables higher head and separate flows to the stator under winding and air gap.
, Description:“Twin flow cooling device for ventilating compact induction motors”

FIELD OF INVENTION
[001] The present Invention relates to twin flow cooling device for ventilating compact induction motors. This is employed in special applications where space is at premium.

BACKGROUND OF THE INVENTION
[002] Motors generate heat during operation. Electric motors of small and medium ratings are either self ventilated or provided with fins on the motor casing's outer body. As the rating increases, air cooling is chosen to ventilate the motors. Finned motors are employed to the extent motor's ventilation is taken care by finning effect.

[003] Design of ventilation systems is one of the challenges during the motor designs as inadequate ventilation critically affects the rating and its life and performance. As regards the small or medium rated motors are concerned, for which market is very huge, any invention towards improving the motor performance is highly beneficial to the Industry. Motors are required to be developed to efficiently absorb the heat during motor operation. Small motors have inbuilt ventilation mechanism where the casing outer surface will dissipate the heat through convection. As the size goes up, the surface area of the casing is increased through finning the outer casing surface. For motors having limitation in fin cooling, fan cooling is the choice as long as the fins meet the cooling requirement. Usually, fan is provided on one side and usually the exciter side of the machine. The axial flow fan mounted on one turbine end (usually on Exciter Side) of generator takes in the air from the core axial holes and throws away on the Exciter side end winding. This air having adequate head created by the rotating fan will be chosen such that the air thrown out will flow back from the core back and goes back to the other side of the motor from where the air flow takes another U turn and enters the axial holes and the air gap. Construction of the end windings of rotor and stator, in motors is such that the stator end winding length is always more than that of rotor and invariably, there will be net length of stator end winding projecting beyond the rotor end winding. Fan is mounted on rotor on this space ie, below the stator end winding.

[004] The disadvantage of the design being followed as per the prior art is that there is limitation in the fan size, especially the fan outer dia. But the fan discharge pressure is dependent on the fan dia. To have the benefit of generating higher head, it is required to increase the dia. Dia cannot be increased as long as the fan tip dia is below the end winding inner dia. Hence there is limitation in this arrangement. Only solution to increase the cold air head to overcome the pressure drop in the air as it flows past the air circuit is to shift the fan from below the end winding to beyond the bearing. This increases the motor length substantially.

[005] The present method of meeting the higher cooling requirement of higher rating motors is to arrange the fans at the ends of the rotor, that is beyond the bearing. Disadvantage with this arrangement is that, it increases the motor length and at the same time bearing access will not be as easy as that in smaller rating designs. However, induction motors employed in emobility shall be compact and light weight. Motors of such higher lengths will not fit into the requirement of having compact sized motors, eg, for applications such as e mobility.

[006] In view of the above, the present invention has been introduced to address the aforesaid issues and serve the purpose efficiently.

OBJECTS OF THE INVENTION
[007] An object of the invention is to propose twin flow cooling device for ventilating compact induction motors which obviates shortcomings of the prior art(s).

[008] Another object of the invention is to propose twin flow cooling device for ventilating compact induction motors which is simple in construction and efficient.

[009] Still another object of the present invention is to provide twin flow cooling device for ventilating compact induction motors which directs the air onto the heat sources, thereby enabling focused cooling.

[010] Yet another object of the present invention is to provide twin flow cooling device for ventilating compact induction motors which improves effectiveness of cooling considerably.

SUMMARY OF THE INVENTION
[011] Accordingly, there is provided twin flow cooling device for ventilating compact induction motors comprising a twin curved ducts integrated to each other, each of which is connected to a flap constituting an assembly, which is secured to rotor/partition flange.

[012] The twin duct assembly acts as a fan due to centrifugal action which is arranged radially on to the rotor collar or rotor clamping plate, in which the inner and outer radii ends are kept open to draw in and discharge out air.

[013] Air flow takes place in two streams, wherein first stream coming out of the inner duct is directed into the stator/ rotor air gap and stator end winding and the second stream emerging out of the second duct directs the air to cool the back of core.

[014] The structure of the twin curved duct is preferably made of non-metallic structural glass, which is composite fibre glass.

[015] The curved double ducts take the air smoothly on to the winding structural glass due to the construction of the ducting air is blown out of the ducts due to centrifugal action, in which the blown air cools the stator end winding and flows back to the front side of the motor, wherein the head created by the duct arrangement due to centrifugal action enables the flow to take place, wherein the fan has an inner ring over which the composite material is built, so that the invention enables higher head and separate flows to the stator under winding and air gap.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[016] Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings of the exemplary embodiments and wherein:-

Figure 1 shows: Induction motor.
Figure 2 shows: Ventilation system.
Figure 3 shows: Rotor for induction motor.
Figure 4 shows: Twin flow cooling device for ventilating compact induction motors according to present invention.
Figure 5 shows: Ventilation of motor in accordance with the invention.
DETAIL DESCRIPTION OF THE PRESENT INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS OF PREFERRED EMBODIMENTS

[017] The present Invention devises an alternative structure of ventilating the induction motor as shown in figure 1 indicating the following features:-
Terminal box-100
Stator winding-101
Shaft-102
Rotor cage and iron-103

[018] A twin curved tube fan has been proposed by the present Invention to achieve additional fan pumping. Here, air flow takes place in two streams, wherein first stream coming out of the inner duct is directed into the stator/ rotor air gap and stator end winding and the second steam emerging out of the second duct directs the air to cool the back of core. After cooling the respective zones, the two streams of air mix up and get circulated through the heat exchanger and comes to the front or drive end of the motor. The cold air coming out of the cooler is forced to the rear end or the non-drive end of the rotor, passing through the axial holes in the core and axial flutes milled in the shaft of rotor as in figure 3.

[019] Now, reference may be made to figure 2 illustrating ventilation scheme, where in one stream of air is forced out radially on to the end winding, from where it goes to the core back. It then moves towards the front end from where it takes a U turn and moves back again to the fan. Heat exchange takes place between the air in circulation to the metal body of the motor, finned or unfinned. The metal body dissipates the heat to the atmosphere.

[020] Air going through the air gap travels longitudinally, absorbing the heat from the rotor and stator cores. The cooling ducts provided in the motor outer housing and the end covers absorb the heat from the incoming hot air and passes on to the water flowing through the ducts. There are two ports, one each for air inlet and one for discharge of the air.

[021] Fan is mounted on the shaft below the stator end winding and this arrangement imparts compactness to the motor. As the motor rating increases, the heat generated will also increase. To meet the increasing heat dissipation, fan needs to be located beyond the end winding and beyond bearings. This arrangement increases the motor length and diameter substantially. As on today there is always a threshold rating for a given motor parameters, the threshold for keeping the fan below end winding is 100kw. To overcome the limitation on having the fan below end winding and improve the cooling capability, it requires an alternative and efficient provision where this rating can be extended beyond the above limit. This will enable compactness in the motors and more efficient cooling at the same time.

[022] The present invention introduces a technology, which achieves the aforesaid objectives i.e. compactness in the motors and more efficient cooling simultaneously.

[023] In the present invention, there is an air flow arrangement as given in figure 2, that ensures higher head and at the same time, focuses the air streams on to the heat sources i.e. stator/rotor air gap and end winding.

[024] Now, reference may be made to figure 4 illustrating twin flow cooling device of the instant invention for ventilation of compact induction motor. Figure 4 depicts the following.

Duct-1, 2
Flap to fasten the fan-3,4
Opening for air flow-5

[025] The twin flow cooling device constitutes twin curved duct. Said twin curved duct comprises two curved ducts (1, 2) integrated to each other and joined with two flaps. Each of the curved ducts (1, 2) is connected to a flap (3, 4) as shown in the figure 4. This assembly of ducts and flaps (1-4) is secured to rotor collar or partition flange, which is intended to carry the rotor.

[026] The twin duct assembly acts as a fan due to centrifugal action which is arranged radially on to the rotor collar or rotor clamping plate. The inner and outer radii ends are kept open to draw in and discharge out air. The total mass flow of air is effectively utilised in the heat exchange process due to focussed air flow.

[027] The structure of the twin curved duct is preferably made of non-metallic structural glass, which is composite fibre glass, that can be moulded to drawing. This type of curved double ducts take the air smoothly on to the winding structural glass due to the construction of the ducting air is blown out of the ducts due to centrifugal action. The blown air cools the stator end winding and flows back to the front side of the motor. The head created by the duct arrangement due to centrifugal action enables the flow to take place. The fan has a inner aluminium ring over which the composite material is built, so that the invention enables higher head and separate flows to the stator under winding and air gap.

[028] Reference may be made to figure 5 showing the following:-

End cover-200
Drive end-201
Fan-202

[029] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particulars claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogues to “at least one of A, B and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B”.

[030] It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims:-