JP7729365B2 - electric motor - Google Patents

Description

This disclosure relates to a structure for cooling the rotor of an electric motor.

A conventional cooling structure for the rotor of an electric motor is described in Patent Document 1. As shown in Figure 6, a conventional electric motor 1 has a stator 4 fixed within a housing 2 of the motor 1, with a rotor 6 rotatably supported inside the stator 4. The rotor 6 has a shaft 8 rotatably supported at both ends by bearings 14, a rotor core 10 fixed around the shaft 8, and end plates 12 fixed to both sides of the rotor core 10 in the axial direction of the shaft. A magnet (not shown) is embedded within the rotor core 10.

To cool the rotor 6, a flow path 16 for a coolant (e.g., oil) is formed in the shaft 8, rotor core 10, and end plate 12. A pair of seal rings 20 are provided on either side of a coolant inlet 18 formed at the end of the shaft 8, and the outlet of a flow path 22 formed in the housing 2 faces between the pair of seal rings 20. This structure allows coolant to be supplied into the rotor 6 even while the rotor 6 is rotating, cooling the rotor core 10. The arrows in the figure indicate the flow of coolant.

A number of stator nozzles 25 are provided within the housing 2, which spray a refrigerant (e.g., oil) toward the stator 4 to cool it, so that the refrigerant is sprayed onto the stator 4 to cool it.

The refrigerant that cools the rotor 6 by passing through the flow path 16 in the rotor 6 and the refrigerant that cools the stator 4 by being applied to it are discharged from an outlet (not shown) formed in the housing 2.

Japanese Patent Application Laid-Open No. 2019-170150

Conventional electric motors have complex structures, including flow channels and seal rings for supplying refrigerant to the rotor, which rotates at high speed. Furthermore, the complex structure, including the addition of seal rings, increases rotational resistance, reducing the energy efficiency of the motor.

The objective of this disclosure is to provide an electric motor that cools the rotor with a simple structure and is energy efficient.

The electric motor of the present disclosure comprises a stator fixed within a housing, a shaft, a rotor core fixed to the shaft, and first and second end plates that sandwich the rotor core from both axial ends of the shaft; a rotor rotatably supported inside the stator; and a rotor nozzle provided within the housing that sprays refrigerant toward the first end plate. The first end plate, the second end plate, and the rotor core each have a plurality of through holes that form a plurality of refrigerant flow paths that pass from the first end plate to the second end plate. Guide portions that guide the refrigerant sprayed from the rotor nozzle to the refrigerant flow paths are formed between the plurality of through holes on the surface of the first end plate opposite the rotor core. The plurality of through holes formed in the first end plate are formed on the same circumference around the axis of the shaft, and the guide portions are formed inside and along the circumference to connect the plurality of through holes formed in the first end plate .

This disclosure makes it possible to provide an electric motor that cools the rotor with a simple structure and is energy efficient.

FIG. 2 is a diagram showing the internal structure of an electric motor. FIG. 10 is a view showing a first end plate. FIG. 10 shows a second end plate. FIG. 3 is a diagram showing the flow of a refrigerant when cooling an electric motor. 10A and 10B are diagrams showing modified examples of the first end plate; FIG. 1 is a diagram showing the internal structure of a conventional electric motor.

An example of an electric motor according to the present disclosure will now be described with reference to the drawings. Figure 1 shows an outline of an electric motor 1 according to the present disclosure. A stator 4 is fixed to a housing 2. The stator 4 has a stator core and a coil wound around the stator core.

A rotor 6 is journaled inside the stator 4 and supported by the housing 2. The rotor 6 has a shaft 8, a rotor core 10 fixed to the shaft 8, and a first end plate 30 and a second end plate 40 that sandwich the rotor core 10 from both axial sides of the shaft 8. An opening is formed in the rotor core 10 in the axial direction, and a magnet is embedded inside. Both ends of the shaft 8 are supported by bearings 14 on the housing.

The first end plate 30, the second end plate 40, and the rotor core 10 each have a plurality of through holes formed therein. These through holes are aligned in the axial direction, forming a plurality of refrigerant passages 46 as a whole.

A rotor nozzle 24 is provided within the housing 2, spraying refrigerant toward the first end plate 30. The rotor nozzle 24 is directed toward the center of the end plate 30. Additionally, multiple stator nozzles 25 are provided, spraying refrigerant toward the end of the stator 4.

Figures 2 and 3 show the end plates in detail. Figure 2 shows the first end plate 30 on the side where the rotor nozzle 24 is provided. The overall shape is circular, with a shaft hole 35 formed in the center through which the shaft 8 passes. Outside the shaft hole 35, multiple roughly arc-shaped through holes 31 are formed at equal intervals on the same circumference. Inside adjacent through holes 31, roughly arc-shaped guide protrusions 33 are formed to connect the through holes 31.

Figure 3 shows the second end plate 40, located on the opposite side from the rotor nozzle 24. It has a circular shape and is approximately the same size as the first end plate 30, and the shaft hole 45 and through hole 41 are also approximately the same shape as those in the first end plate 30 and are formed in the same positions. In addition, an annular protrusion 43 is formed outside the through hole 41 to surround the through hole 41.

The first end plate 30 is fitted onto the shaft 8 so that the guide protrusion 33 faces away from the rotor core 10, and the second end plate 40 is fitted onto the shaft 8 so that the annular protrusion 43 faces away from the rotor core 10, with the rotor core 10 sandwiched between the two end plates 30, 40. At this time, the through holes 31, 41 of the two end plates 30, 40 and the through hole 47 of the rotor core 10 are aligned so that they are in a straight line in the axial direction of the shaft 8.

Figure 4 shows the state in which refrigerant is sprayed from the rotor nozzle 24 and the stator nozzle 25 while the rotor is rotating. When the refrigerant sprayed from the rotor nozzle 24 is sprayed near the connection between the first end plate 30 and the shaft 8, it moves outward on the first end plate 30 due to centrifugal force. Then, some of the refrigerant that reaches the through hole 31 passes through the through hole 31 and through hole 47 and exits the rotor 6 through the through hole 41 in the second end plate 40.

Furthermore, a portion of the refrigerant that moves along the first end plate 30 and reaches the guide protrusion 33 is guided toward the through hole 31, and similarly passes through the through hole 31 and through hole 47 before exiting the rotor 6 through the through hole 41 in the second end plate 40.

The refrigerant that leaves the rotor 6 moves outward on the second end plate 40 due to centrifugal force. When it reaches the annular protrusion 43, it climbs onto the annular protrusion 43 and splashes outward to avoid contact with the stator 4, reaching the housing 2 and then, due to gravity, reaching the bottom of the housing 2.

The refrigerant sprayed from the stator nozzle 25 cools the stator 4 and reaches the bottom of the housing 2 due to gravity.

The refrigerant that reaches the bottom of the housing 2 is discharged outside the housing 2 through an outlet (not shown) provided in the housing 2.

Figure 5 shows a modified example of the first end plate. In this example, annular catchers 55 are formed on the outside of the multiple through holes 51. The catchers 55 are annular protrusions formed on the outside adjacent to the multiple through holes 51 and have a height similar to that of the guide protrusions 53.

In this modified example, the refrigerant that does not enter the through-hole 51 is caught by the catcher 55, thereby increasing the amount of refrigerant guided into the through-hole 51 and cooling the rotor 6 more efficiently.

The above embodiment can be modified as appropriate within the scope specified in the claims. The number, shape, and position of the through holes formed in the first end plate, second end plate, and rotor core are designed as appropriate depending on the degree of heat generation of the rotor, etc. The size, shape, and position of the guide protrusions and annular protrusions are designed as appropriate to efficiently guide the refrigerant into the through-hole structure.

This disclosure allows for optimal cooling of the motor rotor.

REFERENCE SIGNS LIST 1 Electric motor 2 Housing 4 Stator 6 Rotor 8 Shaft 10 Rotor core 14 Bearing 24 Rotor nozzle 25 Stator nozzle 30 First end plate 33 Guide protrusion 40 Second end plate 43 Annular protrusion 50 First end plate (modified example)
53 Guide protrusion

Claims (3)

a stator fixed within a housing;
a rotor having a shaft, a rotor core fixed to the shaft, and a first end plate and a second end plate sandwiching the rotor core from both axial ends of the shaft, the rotor being rotatably supported inside the stator;
a rotor nozzle provided in the housing and configured to spray a coolant toward the first end plate;
and
a plurality of through holes formed in the first end plate, the second end plate, and the rotor core define a plurality of refrigerant flow paths extending from the first end plate to the second end plate;
a guide portion for guiding the refrigerant sprayed from the rotor nozzle to the refrigerant flow path is formed between the plurality of through holes on a surface of the first end plate opposite to the rotor core,
the plurality of through holes formed in the first end plate are formed on the same circumference around the axis of the shaft, and the guide portion is formed along the circumference on the inside of the circumference so as to connect the plurality of through holes formed in the first end plate;
Electric motor. a catcher is formed on the surface of the first end plate outside the through hole;
2. The electric motor according to claim 1. an annular protrusion is formed on the outer side of the through hole of the second end plate;
2. The electric motor according to claim 1.