RU2249898C2 - Liquid-filled electrical machine - Google Patents

Abstract

FIELD: electrical engineering; induction-motor drives of systems handling continuous starting loads at low speed, such as training simulators.

SUBSTANCE: proposed electrical machine is designed for continuous running in working area while carrying maximal loads as heating of stator winding due to enhanced current is compensated for by dielectric liquid 2, such as oil, that fills sealed chamber 1 accommodating wound stator 3 and rotor 4. Through holes 7 are provided on butt-end and cylindrical surfaces 5 and 6, respectively, of stator frame 3 for admitting cold dielectric liquid 2 and discharging hot liquid under action of centrifugal forces. Additionally disposed between sealed chamber 1 and stator frame 3 is closed pipeline 8 carrying cooling agent and provided with delivery pump 14 and cooler 15. Electrical machine running continuously at low speed and repetitive starting loads close to maximal ones is made possible due to effective cooling of its active components.

EFFECT: enhanced power output and torque of electrical machine.

5 cl, 6 dwg

Description

The invention relates to electrical engineering, in particular to the design of electric motors, and can be used in an electric drive with a long duration of starting loads when operating at low speeds with frequent starts and stops, for example, to drive simulator and bench equipment.

Known electric liquid-cooled machine containing a stator with a winding, a rotor and a pressure pump mounted on the rotor shaft / A.C. USSR No. 1236583, H 02 K 9/19, dated 04.10.84, op. bull. No. 21.

In the known construction, cooling occurs due to the difference in pressure of the refrigerant along the gap between the stator and the rotor, which allows a large amount of coolant (coolant) to be pumped through the gap.

The known device is difficult to manufacture, low-tech and requires high costs for its manufacture.

Known sealed electric machine with a housing filled with coolant containing a stator, a rotor, a protective sleeve installed between the stator and the rotor, a pressure pump that circulates the coolant through the hollow axis of the rotor in the pipeline, forming a closed loop with a radiator / A.C. USSR No. 983909, N 02 K 9/19, dated 18.01.80, op. bull. No. 47 /.

A disadvantage of the known machine is the difficulty of ensuring the tightness of the liquid in the rotating parts and their fragility. Since the refrigerant circulation area is limited, cooling of the stator winding is not enough for the engine to work in difficult conditions with frequent starts, at low revs.

Closest to the proposed is a device aimed at increasing power to ensure the operation of an electric machine in a certain speed range by increasing cooling efficiency. Known electric machine filled with liquid, containing a stator with a winding, a rotor, a pressure pump, a heat exchanger, made in the form of a sealed chamber with a stator housing with holes on its end surfaces / A.C. USSR No. 1555765, N 02 K 9/19, dated 04.01.88, op. bull. No. 13 / - prototype.

The disadvantage of the invention is its structural complexity, for example, ensuring tightness in the rotating parts of the bearing assemblies, is not only difficult to manufacture, but also short-lived in operation, since, as a rule, it requires frequent change of seals.

In addition, in the known construction, the area of the sealed chamber, and hence the heat transfer area is limited, the refrigerant is circulated in a small confined space, which does not provide high cooling efficiency, sufficient to work in difficult conditions not only at low revs, but also with a long starting time loads.

The objective of the invention is the expansion of technological capabilities, namely, ensuring the operation of an electric machine at low speeds, with long duration and frequent repetition of starting loads close to maximum, by increasing the cooling efficiency of actively heating elements.

The problem is achieved in that in a known electric machine filled with liquid containing a stator with a winding, with holes on its end surfaces, a rotor, a pressure pump, a heat exchanger, made in the form of a sealed chamber with a stator housing located in it, as a liquid filling the machine, a dielectric fluid was used, and the heat exchanger is additionally equipped with a pipeline closed with a pressure pump and radiator with a refrigerant circulating in it, placed between the stator housing and hermetically th camera, while the holes are made over the entire surface of the stator housing.

The part of the pipeline forming a closed loop with a pressure pump and a radiator is located outside the sealed chamber.

Part of the pipeline is made in the form of a coil enveloping the stator housing.

In this case, the circulation of the refrigerant is directed to the upper part of the sealed chamber.

Oil is used as a dielectric fluid filling the machine.

The installation of a stator with a winding and a rotor of an electric machine in a sealed chamber filled with technical oil ensures effective cooling of the entire surface of the stator both from the outside of the housing and from the inside, due to the presence of through holes in it made over its entire surface. At the same time, oil, being a dielectric material, ensures the safe operation of the machine.

The pipeline, made in the form of a coil with refrigerant circulating in it, thanks to its large cooling area, effectively cools the oil located between the chamber and the stator housing.

Cooled oil is drawn into the holes located on the end surface of the stator housing, since the rotor acts as an intake mechanism in relation to the end surface. In this case, the centrifugal forces arising from the rotation of the rotor discard the cooled oil on the inner cylindrical surface of the stator, which ensures the selection of heat from the winding and leads to its effective cooling.

The oil heated on the winding, taking into account the convection properties, passes through the holes made on the cylindrical surface of the stator housing and rises to the top of the sealed chamber, where it is effectively cooled by the refrigerant circulating in the pipeline, which enters the top of the sealed chamber from the radiator.

The removal of the drive and radiator, providing circulation and efficient cooling of the refrigerant, outside the sealed chamber allows you to increase the circulation area to the required size and solve the problem in the simplest way and at the lowest cost.

The location of the holes throughout the stator housing allows efficient cooling both inside the most heated elements - the stator winding, and outside.

Thus, the proposed invention, thanks to effective intensive cooling, can sufficiently increase the power and torque of an electric machine to use it when operating at low speeds with a long duration of starting loads.

The proposed invention is illustrated by drawings.

Figure 1 presents an electric machine filled with liquid;

Figure 2 is a side view of figure 1;

Figure 3 is a section aa in figure 2;

Figure 4 - electric machine with a closed circuit of the pipeline with a pressure pump drive and a radiator;

Figure 5 - radiator with fan;

Fig.6 is a side view of Fig.5;

7 is a graph of performance indicators of an electric machine filled with liquid, made in accordance with the proposed invention.

The electric machine contains a sealed chamber 1 filled with liquid dielectric oil 2, a stator 3 with a winding and a rotor 4 (see Fig.1-3). Through holes 7 are made in the stator housing on its end 5 and cylindrical 6 surfaces 7. Between the sealed chamber 1 and the stator housing 3 is a pipe 8 made in the form of a coil enveloping the housing 3.

On the upper wall of the sealed chamber 1 are located: a drainage pipe 9, a power supply cable 10 and a filler neck 11. A pipe 8 passes through the side wall of the sealed chamber 1, made of a collapsible one. The joints are sealed with a sealed material 12.

The pipeline 8 with the refrigerant 13 circulating in it (see Fig. 4), enveloping the stator housing 3, extends beyond the hermetic chamber 1 and forms a closed loop with a pressure pump 14 and a radiator 15 mounted on the upper pipe of the pipeline 8.

A fan 16 with a drive motor 17 is installed in front of the side wall of the radiator 15, and a filler neck 18 is located on the upper wall.

The sealed chamber 1 and the radiator 15 are equipped with expansion barrels 19, 20. (Figs. 5, 6).

The device operates as follows.

First, technical oil is poured into the sealed chamber 1 through the neck 11, and a coolant, such as water (not shown), into the radiator 15 through the neck 18.

When starting induction motors, which include an electric machine made according to the invention, the starting current in the stator winding increases 5-7 times compared to the nominal. With prolonged operation in this mode, the windings overheat and the motor fails.

In the proposed design, the pump 14 delivers chilled water 13 from the radiator 15 to the upper part of the sealed chamber 1. The circulation of cold water 13 is indicated by straight arrows. The cooled oil 2 is sucked into the holes 7 made in the end surface 5, while centrifugal forces cast the cooled oil 2 radially to the stator windings 3, through the holes 7 made on the cylindrical surface 6, already heated oil 2 is ejected into the sealed chamber 1. The movement of heated particles is shown by arc arrows.

Figure 7 on the graph shows the operating characteristics of an electric machine, namely an induction motor: torques M and currents I depending on the power P, where:

PZ ₁ - working area of a typical asynchronous electric motor;

PZ ₂ - working area of an asynchronous electric motor, made in accordance with the given utility model;

RZ _max - working area with maximum performance.

The graph clearly shows that when applying the proposed invention, the working area of the induction motor RE ₁ increases to RE ₂ , while I _nom tends to I _max . It follows that the proposed electric machine can work indefinitely in RP _max ., Since the heating of the stator winding, which occurs when the current I increases, is compensated by the cooling system proposed in the invention.

Since the moment M and engine power P are functions of current I with a quadratic dependence:

M = f (I) ² and P = f (I) ² ,

this means that with intensive cooling of an induction motor, it is possible to maintain the maximum value of the useful moment M and the useful power P of the motor, which has wide practical application in drives of various systems. Thus, the proposed design makes it possible to effectively provide cooling of actively heated elements of the stator winding and the entire electric machine as a whole and to obtain the required characteristics for the effective operation of predominantly asynchronous motors at low rotor speeds and frequent starts, which allows the use of an asynchronous motor in starting conditions for a long time .

The invention is proposed to be used in the construction of drives of stands and simulators.

Claims (5)

1. An electric machine filled with liquid, containing a stator with a winding, with holes on its end surface, a rotor, a pressure pump, a heat exchanger made in the form of a sealed chamber with a stator housing located in it, characterized in that as a liquid filling machine, a dielectric fluid is used, and the heat exchanger is additionally equipped with a pipeline closed with a pressure pump and a radiator, with refrigerant circulating in it, placed between the stator housing and the sealed chamber, with Full over the entire surface of the stator housing. 2. The electric machine according to claim 1, characterized in that the part of the pipeline forming a closed loop with a pressure pump and a radiator is located outside the sealed chamber. 3. The electric machine according to claim 1 or 2, characterized in that the portion of the pipeline is made in the form of a coil enveloping the stator housing. 4. The electric machine according to one of claims 1 to 3, characterized in that the circulation of the refrigerant from the radiator is directed to the upper part of the sealed chamber. 5. An electric machine according to one of claims 1 to 4, characterized in that oil is used as the dielectric fluid filling the machine.

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