JP2013062912A - Cooling structure of rotary electric machine - Google Patents

Abstract

In a rotating electrical machine that cools a coil by discharging a cooling liquid from a rotor shaft, a decrease in the cooling liquid applied to the coil during high rotation is suppressed.
A rotor shaft 16 is provided with a plurality of through holes 26 and 28 for discharging coolant. One through hole 26 is provided with a check valve 32 that closes the through hole 26 at a predetermined rotational speed or higher. When the rotational speed increases and the amount of coolant applied to one time decreases, the through hole 26 is closed by the check valve 32, and the coolant is discharged from the one through hole 28 in a concentrated manner. As a result, the amount of the cooling liquid applied to one place of the coil is increased, and the cooling liquid is sent to the inside of the coil.
[Selection] Figure 1

Description

  The present invention relates to a rotating electrical machine, and more particularly to a structure related to cooling thereof.

  An electric motor that converts electrical energy into rotational kinetic energy, a generator that converts rotational kinetic energy into electrical energy, and an electric device that functions as both the motor and the generator are known. Hereinafter, these electric devices are referred to as rotating electric machines.

  A rotating electrical machine that cools with a liquid is known (see Patent Document 1 below). In the rotating electrical machine described in Patent Document 1 below, when the rotating electrical machine reaches a high speed, oil (coolant) is discharged from the rotor shaft to cool the rotor. A technique for cooling a coil with oil discharged from a rotor shaft is also known (see Patent Document 2 below).

JP 2009-118714 A JP 2009-118686 A

  When the supply amount of the cooling liquid is constant with respect to the rotation speed of the rotating electrical machine, the amount of the cooling liquid discharged from one hole is reduced when the rotation speed becomes high. When cooling a fixed component around the rotor such as a coil with the cooling liquid discharged from the rotor shaft, the decrease in the discharge cooling liquid described above is 1 for the cooling liquid when viewed from one place on the fixed structure such as the coil. It appears as a decrease in the amount of coolant each time it is applied. There is a problem that the cooling of the coil or the like is not sufficiently performed due to the decrease in the coolant every time it is applied.

  An object of the present invention is to suppress a decrease in the amount of cooling liquid every time it is applied once.

  In the rotating electrical machine according to the present invention, the rotor shaft is provided with a plurality of holes for discharging the coolant toward the coil. This hole is a through hole that connects the flow path formed inside the rotor shaft and the outer peripheral surface of the rotor shaft. Cooling liquid is supplied to the flow path inside the rotor shaft from a cooling liquid supply source. The amount of coolant supplied from the coolant supply source is limited to be smaller when the rotating electrical machine is equal to or higher than the first rotational speed than when it is proportional to the rotational speed. In a situation where the supply amount of the coolant is restricted, when the rotating electrical machine reaches the second rotational speed or higher, a part of the plurality of through holes is closed by the closing means.

  The closing means may be a check valve that operates by centrifugal force generated by rotation of the rotating electrical machine.

  The cooling liquid supply source can make the amount of the cooling liquid supplied constant at a rotation speed equal to or higher than the first predetermined rotation speed.

  The discharge amount of the cooling liquid per one through-hole increases, and a decrease in the amount of the cooling liquid every time the cooling liquid is applied can be suppressed.

1 is a cross-sectional view illustrating a schematic configuration of a rotating electrical machine 10. FIG. 3 is an axial cross-sectional view of a rotor shaft 16. It is a figure which shows the supply amount of an oil pump. It is a figure which shows the structure of the through-hole 26 and the check valve 32 which closes this. It is the figure which looked at the check valve 32 from the downward direction of FIG. It is a figure which shows the quantity of the cooling fluid supplied from a through-hole.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view illustrating a schematic configuration of the rotating electrical machine 10. The rotating electrical machine 10 includes a rotor 12 and a stator 14. The rotor 12 has a substantially columnar shape, and the stator 14 has a substantially cylindrical shape and is disposed so as to surround the rotor 12. The rotor 12 includes a rotor shaft 16 that is rotatably supported by a bearing (not shown), and a rotor core 18 that rotates integrally with the rotor shaft 16. The stator 14 includes a wound coil 20, and by supplying electric power to the coil 20 from the outside, a rotating magnetic field is formed inside the stator 14. The rotor 12 is magnetically coupled to the rotating magnetic field formed by the stator 14 and rotates.

  The hollow portion of the rotor shaft 16 is a flow path 24 through which lubricating oil supplied from the oil pump 22 flows. Lubricating oil is supplied by the oil pump 22 to a bearing that supports the rotor shaft 16, to each part of the rotating electrical machine, and to a position that requires lubrication of a mechanism and structure disposed around the rotating electrical machine 10. . The lubricating oil also functions as a coolant that cools each part of the rotating electrical machine 10 and the like. The lubricating oil also functions as a hydraulic fluid for the hydraulic actuator. For example, when the rotating electrical machine 10 is disposed in a transaxle of a vehicle, it functions as a hydraulic fluid for operating a clutch and a brake of a transmission mechanism. Hereinafter, focusing on the cooling function of the lubricating oil, the lubricating oil will be referred to as a coolant. Further, the internal flow path 24 formed in the rotor shaft 16 is referred to as a coolant flow path 24.

  FIG. 2 is an axial cross-sectional view of the rotor shaft 16. As shown in FIGS. 2 and 1, the rotor shaft 16 is provided with through holes 26, 28 that connect the internal coolant flow path 24 and the outer peripheral surface. In this rotating electrical machine 10, two through holes are provided, but more through holes may be provided. The coolant supplied from the oil pump 22 to the coolant channel 24 is discharged from the through holes 26 and 28 toward the periphery of the rotor shaft 16. On the radially outer side of the position where the through holes 26, 28 are provided, the coil 20, in particular, the coil end 30 that is a portion protruding from the end surface of the core of the stator 14 is located. The through holes 26 and 28 are arranged so that the coolant discharged from the through holes 26 and 28 is directed to the coil end 30.

  The oil pump 22 has a discharge amount proportional to the rotation speed of the oil pump up to a certain rotation speed, and has a characteristic in which the discharge amount is limited to a discharge amount smaller than the proportional discharge amount when the rotation speed is exceeded. It is done. Hereinafter, the rotation speed at the boundary between the discharge amount proportional to the rotation speed and the limited discharge amount is referred to as the boundary rotation speed. Further, as an example of the limited discharge amount, there is a characteristic that the discharge amount is constant in a speed region equal to or higher than the boundary rotational speed. This characteristic is shown by a solid line in FIG.

  In FIG. 3, the horizontal axis represents the rotation speed of the oil pump 22, and the vertical axis represents the amount of coolant supplied from the oil pump 22 to the coolant flow path 24. When the rotational speeds of the oil pump 22 and the rotating electrical machine 10 have a proportional relationship, the horizontal axis also indicates the rotational speed of the rotating electrical machine 10. The aforementioned boundary rotational speed is indicated by the symbol N1 in FIG. Below the boundary rotational speed N1, the supply amount is proportional to the rotational speed, and above that, it is constant.

  In a region where the supply amount is constant, the amount of cooling liquid discharged from one through hole decreases as the rotor shaft 16 rotates once as the rotational speed increases. When viewed from one place on the circumference of the coil end 30 to which the discharged coolant is applied, the coolant is applied to this place when the through holes 26 and 28 are opposed to each other. For one location on the circumference, the rotation speed increases and the discharge amount per rotation of one through-hole decreases, so that the amount of coolant when the coolant is applied to that location once decreases. It means to do. When the supply amount of the cooling liquid is reduced per time, the cooling liquid is not sufficiently supplied to the coil end 30, particularly the inside thereof. The coil end 30 has coil conductors arranged in a complicated manner, and is cooled to the inside by cooling liquid entering the coil end 30 from the gap between the coil conductors. However, as described above, if the amount of the cooling liquid applied per time is small, the cooling liquid only hits the surface of the coil end 30 and the cooling liquid does not enter the inside, and the internal cooling may not be sufficient. is there.

  In the rotating electrical machine 10, in order to suppress a decrease in the amount of coolant that is applied once, when the rotating electrical machine 10 reaches a predetermined rotational speed, the number of through-holes related to discharge of the coolant is reduced. . A part of the through holes 26, 28, that is, one through hole 26 is provided with a closing means for closing the through hole 26. The closing means is specifically a check valve 32.

  4 and 5 are diagrams showing the detailed structure of the check valve 32. FIG. The through-hole 26 has a narrow diameter portion 34 with a small diameter at the outer portion of the rotor shaft 16 and a thick diameter portion 36 with a large diameter at the inner portion, which are connected to each other. A ball 38 having a diameter larger than the inner diameter of the small diameter portion 34 is disposed in the space inside the large diameter portion 36. A holding plate 40 for holding the ball 38 is provided at the opening of the large-diameter portion 36 on the coolant flow path 24 side so as to cover the opening. The holding plate 40 is substantially circular, and is provided with a slit 42 so as to avoid the position where the ball 38 is supported or the center of the holding plate. In this example, four arc-shaped slits arranged on the same circumference are provided. A biasing force is applied to the ball 38 by a spring 44 toward the holding plate 40, that is, in a direction away from the small diameter portion 34.

  When the rotational speed of the rotor shaft 16 is low, the ball 38 abuts on the holding plate 40 by the urging force of the spring 44 and opens the small diameter portion 34. As the rotational speed increases, the centrifugal force acting on the ball 38 increases, and when this becomes greater than the urging force of the spring 44, the ball 38 closes the opening on the inner diameter side of the narrow diameter portion 34 and closes the through hole 26. The ball 38 functions as a valve body that operates by centrifugal force acting on the ball 38. The rotational speed at which the through hole 26 is closed is shown in FIG. 6 as the closed rotational speed N2. After the through hole 26 is closed, the coolant is discharged only from the through hole 28, and the coil end 30 is cooled.

  FIG. 6 is a diagram showing the flow rate of the coolant discharged from one through hole 28 and the amount of one time applied to a location where the coil end 30 is located. The flow rate discharged from the through hole 28 is indicated by a solid line, and the amount of one time is indicated by a broken line. Up to the boundary rotational speed N1, the flow rate and the amount per operation increase as the supply amount of the oil pump 22 increases. When the boundary rotational speed N1 is exceeded, the supply amount from the oil pump 22 becomes constant, and the flow rate discharged from the through hole 28 becomes constant. On the other hand, since the rotational speed of the rotor shaft 16 is increased, the discharge amount per one rotation is decreased, and the amount of the coolant applied to the portion where the coil end 30 is provided is also decreased. When the closing rotational speed N2 is reached, one through hole 26 is closed, so that the flow rate of the through hole 28 is doubled. The amount of cooling liquid that is applied at one time is also doubled. Further, as the rotational speed increases, the flow rate and the amount of one time are reduced accordingly. However, compared with the case where the through-hole 26 is not closed (indicated by the alternate long and short dash line in FIG. 6), the flow rate and the amount of one time can be increased. Thereby, the quantity of the coolant sent into the coil end 30 can be increased as compared with the case where the number of through holes is not reduced, and the cooling performance of the coil is improved.

  The boundary rotational speed and the closing rotational speed can be arbitrarily determined based on the usage environment and usage conditions of the rotating electrical machine 10. The number of through holes can be three or more, and a closing means can be provided in a plurality of through holes. When providing a closing means in a plurality of through holes, the rotation speed (closing rotation speed) at which each through hole is closed can be made different.

  The closing means for closing the through hole 26 may take other configurations. For example, the valve body that closes the opening of the small-diameter portion 34 of the through hole may not be a ball shape, and may be, for example, a plate shape. The blades may employ other springs such as a leaf spring in addition to a coil spring. A part of the leaf spring may block the opening. Furthermore, a mechanism other than a valve that operates by centrifugal force may be provided. For example, it is possible to provide a flow path for the coolant that reaches the through hole separately in each of the two through holes, and provide a closing means such as an electromagnetic valve in the flow path. When three or more through-holes are provided, a set can be formed by the through-holes that are simultaneously closed, and a coolant flow path can be provided for each set.

  10 rotating electrical machines, 12 rotors, 14 stators, 16 rotor shafts, 20 coils, 22 oil pumps, 24 coolant flow paths, 26, 28 through holes, 30 coil ends, 32 check valves (closing means), 38 balls.

Claims (3)

A rotor including a rotor shaft;
A stator having a coil and disposed outside the rotor;
A coolant supply source for supplying the coolant;
A cooling structure for a rotating electrical machine having
The rotor shaft is provided with an internal flow path and a plurality of through holes connecting the flow path and the outer peripheral surface of the rotor shaft.
The coolant supplied from the coolant supply source is discharged toward the coil through the flow path and the through hole,
The cooling liquid supply source limits the amount of the cooling liquid to be supplied when the rotating electrical machine has a rotation speed equal to or higher than the first predetermined rotation speed, compared with the case where the rotation liquid is proportional to the rotation speed.
further,
A closing means for closing a part of the plurality of through-holes when the supply amount of the cooling liquid is limited as described above and the rotating electrical machine has a rotation speed equal to or higher than a second predetermined rotation speed;
A rotating electric machine.   2. The rotating electrical machine according to claim 1, wherein the closing means is a check valve that operates by a centrifugal force generated by the rotation of the rotating electrical machine.   3. The rotating electrical machine according to claim 1, wherein the coolant supply source makes the amount of coolant supplied constant at a rotational speed equal to or higher than the first predetermined rotational speed.

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