RU2128391C1 - Self-cooling system for face-mounted electrical machine - Google Patents

Abstract

FIELD: electrical engineering; single-stator and single- rotor induction machines. SUBSTANCE: radial cooling ducts are made in rotor rim, its winding conductors, and under bearing surface of stator magnetic core. Rotor has plate-type section in the form of hollow cone provided with external ribs. Radial cooling ducts in rotor rim and in its winding communicate on gas jet inlet side with separate vacuum spaces abutting against inner and outer conical surfaces of rotor, respectively, and on outlet side, with common delivery space around rotor rim. EFFECT: improved efficiency of cooling system which ensures improved reliability of machine. 4 cl, 7 dwg

Description

 The invention relates to electrical engineering, and in particular to methods and means of cooling asynchronous electric machines with one stator and one rotor, in which structural elements or devices that implement the principle of self-ventilation are used to create a directed movement of cooling gas (air) through the ventilation ducts or blow off the outer surface of the machine .

 External self-blowing and internal self-ventilation with an open cycle of cooling air circulation are widely used in cooling systems of electric motors with a coaxial arrangement of the stator and rotor magnetic circuits [1,2].

 A known design of the end electric machine with external blowing during self-ventilation [3].

 Its disadvantage is the low efficiency of the cooling system, especially at low rotational speeds of the machine shaft.

 Mechanical synchronous generators [4] are also known, having a rotor in which the pole system is used as a fan. This is achieved due to the presence of an internal cavity, as a result of which cooling air entering this cavity through special holes of the rotor, when the latter rotates, is ejected into windows made on the periphery of the rotor.

 The disadvantages of this means of implementing internal self-ventilation are the complexity of the design of the rotor and the technology of its manufacture, as well as the inevitability of imbalances in the rotor of a technological nature due to the use of welding operations in its manufacture. In addition, since the radial length of the inner cavity of the rotor is small, the speeds of the cooling air flow inside the machine may not be high enough due to the small aerodynamic pressure created by the rotor during rotation, which reduces the efficiency of the cooling system.

 Closest to the claimed invention is a ventilation cooling system that implements the principle of internal self-ventilation in a mechanical motor [5], having an additional short-circuit ring adjacent to a non-working end surface of the yoke of the magnetic circuit and equipped with ribs of variable height, acting as centrifugal fan blades. In this case, the cooling air flow enters the machine through the ventilation windows of the housing located on the side of the radial ribs, and is thrown out through the windows of the housing from the side of the peripheral frontal parts of the field coil.

 The disadvantage of this cooling system is its low efficiency. In particular, the inner frontal parts of the field winding located on the side of the machine shaft are poorly washed by the air flow. The cooling air stream "washes" mainly the peripheral elements of the stator and rotor windings.

 In addition, the radial length of the ribs of the additional ring (fan blades) may not be sufficient to create the required aerodynamic pressure (the necessary speeds of air flow), and increasing the length of the ribs will increase the radial dimensions of the machine. This ventilation cooling system does not have a special branched network of channels for the flow of cooling air, which significantly complicates the cooling of fuel elements, especially those located in the inner area of the machine surrounding the shaft.

 The claimed invention solves the problem of increasing the efficiency of the ventilation cooling system, and thereby the operational reliability of the end electric machine.

 This is achieved by the fact that in a ventilation cooling system that implements the principle of self-ventilation, comprising a rotor with ventilation elements enclosed in a hollow body, input and output windows of the housing and ventilation ducts, according to the invention, the rotor is equipped with a system of ventilation ducts having the form of radial holes of increased length, made in the rim of the rotor and the conductors of its short-circuited winding, and the radial channels of the rim of the rotor are located relative to the non-working end plane of the magnetic circuit so, h then this plane partially falls into the working space of the channels.

 In addition, the disk-shaped portion of the rotor, having the shape of a hollow cone, is provided with external ribs acting as fan blades.

 In this case, the radial channels of the rotor rim and its short-circuited winding from the inlet side of the gas (air) jets communicate with separate rarefaction (suction) regions adjacent, respectively, to the inner and outer conical surfaces of the rotor, and from the outlet side, to the common discharge region surrounding the rim of the rotor.

 Moreover, the inner surface of the machine body in the discharge area is equipped with radial guide ribs having a small radial clearance with the rim of the rotor and dividing the overpressure region into separate cells, and the output shaft section of the electric machine, having the shape of a flange, is provided on its end surface with radial open from the side housing covers with channels for supplying cooling gas (air) into the cavity of the machine.

 In this case, the movement of a part of the cooling gas (air) stream is organized by a system of radial channels laid under the supporting surface of the stator magnetic circuit.

 The creation of the necessary aerodynamic pressure at the outlet of the ventilation duct and the increase in the ventilation system productivity are ensured both due to the high throughput of a large number of radial channels and due to the effective suction-discharge action exerted on the moving gas (air) flows by the structural elements of the rotating rotor.

 The invention is illustrated by drawings.

 In FIG. 1 shows a cross-sectional view of an end-face asynchronous electric machine, structural elements of a cooling system, and directions of gas (air) flow.

 In FIG. 2 - in a scan, the cross section of the ribs of the end surface of the rotor shaft (section. E - E, Fig. 1).

 In FIG. 3 - section of radial channels made in the conductors of the short-circuited rotor winding (section A - A, Fig. 1).

 In FIG. 4 is a cross-sectional view of the stator housing in the area of the ventilation ducts (section B - B, Fig. 1).

 In FIG. 5 - section of the ribs of the conical part of the rotor (sec. I - I, Fig. 1).

 In FIG. 6 - section along the rim of the rotor in the area of the ventilation ducts (section. B - B, Fig. 1).

 In FIG. 7 is an external view of one of the windows in the stator housing (View G, FIG. 1).

 Self-ventilation cooling system of the end electric machine operates as follows.

The cooling gas (air) flows enter the machine body from two sides:
through the cavity formed by the surfaces of the shaft 1 and cover 2, on the one hand (in Fig. 1 - on the left) and through the holes 3 available in the cover 4 - on the other (in Fig. 1 - on the right).

 Gas (air) flows entering the machine on the left are captured by the ribs 5 (Fig. 2) available on the end surface of the shaft 1 and are involved in rotational motion. In this case, due to centrifugal inertia forces, the air jets located in the channels 6 formed by the ribs 5 move from the axis of rotation of the shaft and fall the annular gap 7 between the stator housing 8 and the rotor hub 9. Thus, the cavity of the machine body is filled with cooling gas (air) side of the inner frontal parts of the stator and rotor windings. The gas (air) masses arriving in this cavity continue to move along the system of radial channels 10 made in the short-circuited winding of the rotor 9, consisting of radial conductors 11 and closing rings 12, 13 (Fig. 3), as well as along the system of radial channels 14, passing under the idle surface of the stator magnetic circuit 15 (Fig. 4). In addition, part of the flow flows through the annular gap between the working surfaces of the magnetic circuits 15 and 16 of the stator and rotor. The ribs 17, located on the conical surface of the rotor, form inclined channels 18 through which cooling gas (air) is supplied to the corresponding radial channels 10 of the rotor winding. The positive value of the ribs 17 is manifested in the fact that they increase the cooling surface of the rotor and increase its mechanical rigidity. In addition, when the rotor rotates, the gas (air) masses entering the body cavity are driven and discarded in the direction from the axis of rotation to the periphery. This creates an additional aerodynamic pressure, which improves the cooling conditions of the inner frontal parts of the stator and rotor windings and promotes the advancement of gas (air) jets along radial channels to the peripheral part of the cavity of the machine.

 Gas (air) flows entering the machine to the right (Fig. 1), first through the openings 3 fill the annular cavity 19 between the cover 4 and the outer surface of the housing 20, and then through the openings 21 of the housing 20 fill the cavity 22 formed by the inner surfaces of the rotor 9 and case 20. In this case, the radial channels 23 of the rim of the rotor 9, passing under the idle surface of its magnetic circuit 16 (Fig. 6), are filled with cooling gas (air) from the cavity 22.

 When the rotor 9 rotates, the gas (air) masses located in the radial channels 10 and 23 move in the direction from the axis of rotation to the periphery, as a result of which there is a continuous movement of cooling gas (air) flows along the surfaces of the rotor fuel elements.

 The use of the suction-discharge effect of many rotating radial channels of the rotor, having an elongated shape and communicating with the suction areas of the cavity of the machine, can dramatically increase the performance of the ventilation system and improve the cooling conditions of all elements of the machine.

 Under the pressure created by the gas (air) jets emerging from the radial channels, the heated gas (air) masses are displaced from the peripheral part of the machine cavity to the windows 24 located on the side of the external frontal parts of the field winding in the stator housing. In this case, the directed movement of the outgoing air flows to the windows 24 is organized using ribs 25 made on the inner surface of the housing 20 and having a small radial clearance with the rim of the rotor. The ribs 25 exclude the rotation of the gas (air) jets emerging from the radial channels of the rotor of the rotor and specify the direction of movement of the spent (heated) gas (air) masses from the cells 26 formed by these ribs to the exit windows 24.

 Gas (air) streams directed through the stator channels 14 and through the working gap between the surfaces of the magnetic circuits 15 and 16 are directed towards the same windows.

 Windows 24 (Fig. 7) are protected from foreign objects by mesh filters 27 pressed to the windows with the help of strips 28.

 The combined effect of the ventilating elements of a rotating rotor having an original design on the cooling gas (air) entering the cavity of the machine in combination with the creation of a dense network of radial ventilation ducts, made so that the cooling gas (air) jets passing through them are in direct contact with the heat-generating elements, as well as a rational overall layout of the machine, can significantly increase the efficiency of its self-ventilation due to increased ventilation performance an irrigation system and improving the cooling conditions of heating elements, which will contribute to increasing the reliability of the machine and its resource.

Claims (4)

 1. The ventilation system of cooling of the end face electric machine, which implements the principle of self-ventilation and includes an output shaft, a rotor with venting elements enclosed in a hollow body of the machine, input and output windows of the machine body and ventilation ducts, characterized in that in the rim of the rotor, the conductors of the rotor winding and under the supporting surface of the stator magnetic circuit, radial ventilation channels are made, and the rotor is made with a dish-shaped section having the shape of a hollow cone, equipped with external ribs, while the radial s ventilation channels of the rotor rim and the rotor winding from the upstream side in the gas jets are in communication with separate areas of rarefaction adjacent respectively to the inner and outer conical surfaces of the rotor and the output-side - with a total discharge area surrounding the rotor rim.  2. The system according to claim 1, characterized in that the inner surface of the machine body in the discharge area is provided with radial guide ribs dividing this area into separate cells.  3. The system according to claim 1. characterized in that the output shaft of the electric machine is made in the form of a flange equipped with radial channels on its outer end surface for supplying cooling gas to the cavity of the machine body.  4. The system according to claim 1, characterized in that the radial ventilation ducts under the supporting surface of the stator magnetic circuit communicate with a region of the cavity of the machine body adjacent to the outer conical surface of the rotor.

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