ELECTRIC MOTOR

Abstract

This utility model pertains to electrical engineering. The technical result is efficient cooling of an electric motor. The electric motor comprises a support, a stator, a rotor, and a rotating shaft, on which two axial fans with identical technical characteristics are rigidly mounted at the ends of the motor. Cooling air ducts are provided in the support. The fans create counter-current airflows at a distance up to the midpoint of the rotor shaft. The ducts in the support ensure air movement from the midpoint of the rotor shaft through the end portions of the stator winding, in an axial-radial direction through the air gap between the rotor and stator, and in an axial-radial direction through sub-slot channels of the rotor core, with an outlet through radial channels into the air gap. Air circulation in the electric motor cooling system is carried out in a closed loop. The electric motor additionally includes a tubular heat exchanger, in which water is used as a secondary coolant.2 z.p. f-ly, 1 il.

Description

[0001] The utility model relates to electric motors.

[0002] Electric motors of any type generate heat during operation. To maintain proper operation, excess heat must be removed, maintaining the temperature within acceptable limits.

[0003] A self-braking dual axial asynchronous electric motor is known, including a stator and a rotor placed in a housing, in the central part of which a network of radial ventilation ducts is made, connecting the outer surface of the stator housing, conjugated with the atmosphere, with the internal central cavity of the machine, along the inner surfaces of the rotor there are ventilation ducts connected to a network of radial ventilation ducts passing under the supporting surfaces of the magnetic circuits of the rotors, exiting onto the outer surfaces of the annular disks of the rotor, and on the outer surfaces of the rotor there are ventilation blades (patent RU 2642435, published 01 / 25 / 2018. Bulletin No. 3). According to the known solution, cooling of the air washing the surfaces of the electric motor parts is not provided, and the system itself, judging by its description, is open or open.

[0004] A disadvantage of the known solution is the dependence of the electric motor cooling system's efficiency on environmental parameters. While the amount of heat generated during electric motor operation can be estimated by calculation or experiment, the actual heat drop between the electric motor and the surrounding environment is unknown, as the ambient temperature, and therefore the air drawn from it for cooling, can vary widely. Another disadvantage of the known solution is the placement of ventilation blades on the outer surfaces of the rotor, as this complicates the rotor design and its repair, if necessary (for example, in the event of failure or breakage of individual blades).

[0005] An electric motor is known with an improved cooling system, including a fan mounted on a rotating shaft and a tubular heat exchanger through which air passes after contact with hot motor components. The secondary coolant is a cooling liquid (patent US20110227433A1, September 22, 2011). A disadvantage of this solution is that cooling efficiency and, in general, the performance of the electric motor depend on the technical integrity of the single fan. If the fan fails, the electric motor will quickly fail due to overheating.

[0006] The closest prototype of the utility model in terms of the set of essential features is a three-phase asynchronous motor with a three-fan cooling system with full air circulation, including a support, a stator, a rotor, a rotating shaft and a group of fans fixedly attached to the rotor shaft, wherein the support contains channels for cooling air, and the fans are switched on alternately (patent CN 104505970A, published 08.04.2015). According to the known solution, the fans differ from each other. One of them, in particular, is a centrifugal fan. The disadvantages of the known solution include the fact that the cooling system actually constantly operates in transient modes, which is due to the alternate switching on of the fans. This not only complicates the electric motor control system but also calls into question the efficiency of the cooling system.In addition, the disadvantages of the known solution include an unjustifiably large range of electric motor components: the use of three fans that differ in type, design, and technical characteristics.

[0007] The technical problem that the proposed utility model is aimed at solving is the creation of a cooling system for electric motor parts.

[0008] The technical result of the implementation of the utility model is to ensure efficient cooling of the electric motor.

[0009] The technical problem is solved due to the fact that in an electric motor, including a support, a stator, a rotor, a rotating shaft and a group of fans fixedly mounted on the rotor shaft, wherein channels for cooling air are made in the support, the group of fans consists of two identical, according to technical characteristics, axial-type fans placed on the rotor shaft at the ends of the engine and creating counter-current air flows at a distance to the midpoint of the rotor shaft, the channels in the support ensure the movement of air from the midpoint of the rotor shaft through the end parts of the stator winding, in the axial-radial direction through the air gap between the rotor and the stator and in the axial-radial direction through the sub-slot channels of the rotor core with an outlet through the radial channels into the air gap, the air circulation in the cooling system of the electric motor is carried out along a closed circuit, wherein the electric motor additionally includes a tubular heat exchanger,in which fresh or mineralized water is used as a secondary coolant,

[0010] The design of the proposed electric motor is explained by the drawing (Fig.), which shows a simplified longitudinal section of the electric motor.

[0011] The following positions are indicated on the figure:

[0012] 1 - support,

[0013] 2 - stator,

[0014] 3 - rotor,

[0015] 4 - rotating shaft (rotor shaft),

[0016] 5 - fan,

[0017] 6 - heat exchanger,

[0018] 7 - casing.

[0019] The arrows show the direction of air movement.

[0020] Rotor 3 is fixedly fixed on rotating shaft 4, wherein rotor 3 and rotating shaft 4 are located coaxially with stator 2.

[0021] The rotating shaft 4, which can also be called the rotor shaft, is installed in the support 1.

[0022] Two fans (5) are fixedly mounted on rotating shaft (4). Both fans (5) are axial. Axial fans are known to provide higher air flow rates at lower pressures than centrifugal fans. Furthermore, axial fans require less drive energy and produce less noise. According to the applicant, these qualities make axial fans preferable for electric motor cooling.

[0023] Heat exchanger 6 is located at the top of the electric motor. It is preferable to have a tubular heat exchanger with finned tubes. The tube sheet of heat exchanger 6 is insulated from the space surrounding the electric motor by the internal surfaces of casing 7. Water is used as a secondary coolant in the electric motor. Fresh or mineralized water may be used. Water is pumped through the tubes of heat exchanger 6 by a pump (not shown in the figure).

[0024] The casing 7 is installed at the top of the electric motor, above the heat exchanger 6 and is fixed on the support 1.

[0025] The air circulation within the electric motors is closed, that is, the space through which the air pumped by the fans 5 moves is isolated from the space surrounding the electric motor.

[0026] The electric motor proposed as a utility model operates as follows.

[0027] When rotor 3 rotates, heat is released in stator 2. Two fans 5 rotate continuously with rotor 3. Air flows generated by fans 5 move towards each other along the axis of rotor 3. In the area of ​​the central point of rotating shaft 4, the direction of air movement changes: channels in support 1 provide air movement from the midpoint of shaft 4 of rotor 3 through the end parts of the winding of stator 2, in the axial-radial direction through the air gap between rotor 3 and stator 2 and in the axial-radial direction through the sub-slot channels of the rotor core 2 with an outlet through radial channels into the air gap. Next, the hot air is directed to heat exchanger 6, where it transfers excess heat to the coolant pumped through the tubes of heat exchanger 6 by a pump. After heat exchanger 6, the cooled air, moving along casing 7, is directed to fans 5, repeating the circulation.

[0028] According to the applicant's research, as well as literature data, the use of two 5-axis fans allows for greater airflow with the same power consumption compared to centrifugal fans. This ensures greater heat transfer in the electric motor cooling system, thereby increasing its efficiency.

[0029] Directed air movement along the axis of the electric motor, and then in the radial direction and through the frontal part of the stator winding 2 ensures heat removal from the hottest parts of the electric motor and, therefore, its effective cooling.

[0030] Example of the implementation of the utility model.

[0031] The applicant has manufactured an asynchronous electric motor incorporating the cooling system described in this application. The electric motor's power is 1600 kW at a rotational speed of 3000 min-1. -1The electric motor has successfully completed extensive testing. Preparations for serial production are currently underway. During testing, no instances of overheating or failure due to temperature violations were recorded. This allows us to conclude that the stated technical result has been achieved.

Claims

1. An electric motor comprising a support, a stator, a rotor, a rotating shaft and a group of fans fixedly mounted on the rotor shaft, wherein the support has channels for cooling air, characterized in that the group of fans includes two axial-type fans with identical technical characteristics, located on the rotor shaft at the ends of the motor and creating counter-current air flows at a distance to the midpoint of the rotor shaft, the channels in the support provide air movement from the midpoint of the rotor shaft through the end portions of the stator winding, in the axial-radial direction through the air gap between the rotor and the stator and in the axial-radial direction through the sub-slot channels of the rotor core with an outlet through the radial channels into the air gap, air circulation in the cooling system of the electric motor is carried out along a closed circuit, additionally includes a tubular heat exchanger in which water is used as a secondary coolant.

2. An electric motor according to paragraph 1, characterized in that fresh water is used as a secondary coolant.

3. An electric motor according to paragraph 1, characterized in that mineralized water is used as a secondary coolant.

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