JP2013110910A - Rotary electric machine - Google Patents

Abstract

A rotating electrical machine capable of warming up a cooling medium at an early stage with a simple configuration and improving the cooling efficiency of the rotating electrical machine is provided.
A rotor 14 of a rotating electrical machine 10 has end plates 20 provided at both ends in an axial direction 18. A flow path 26 is formed in the rotor shaft 12, and the flow path 26 supplies a cooling medium to the end surface 20 a of the end plate 20. The end surface 20a is formed so as to be curved to the inner side of the rotor 14 on the outer side in the radial direction than on the inner side in the radial direction. Due to the shape of the end face 20a of the end plate 20, only the low-temperature cooling medium is introduced into the air gap 22 through the end face 20a and can be warmed up by dragging friction there.
[Selection] Figure 1

Description

  The present invention relates to a rotating electrical machine, and more particularly to an improvement in a cooling structure of the rotating electrical machine.

  The rotating electrical machine includes a rotor shaft, a rotor fixed to the rotor shaft, and a stator disposed around the rotor. The stator has a coil, and a rotating magnetic field is generated when a current flows through the coil. The rotor is rotated by an electromagnetic action acting between the rotating magnetic field and the rotor.

  Generally, a rotating electrical machine generates heat by driving the rotating electrical machine. When the rotating electrical machine is a permanent magnet type rotating electrical machine, the permanent magnet provided on the rotor or the coil end of the stator generates heat. When these generate heat and the temperature rises, the operating efficiency of the rotating electrical machine decreases. Therefore, there is an example in which the rotating electrical machine is cooled by the refrigerant.

  Patent Document 1 listed below discloses a cooling device that supplies a cooling fluid to a gap between a rotor and a stator to cool a rotating electrical machine. A groove for discharging the cooling medium staying in the gap to the outside is formed on the surface of the rotor of this document. By promoting the discharge of the cooling medium by the groove, power loss due to stirring of the cooling fluid in the gap is suppressed when the rotating electrical machine is driven.

  Patent Document 2 below discloses a structure for cooling a rotating electrical machine by flowing a cooling medium into a gap between a stator and a rotor. Also in this document, in order to reduce the friction loss due to the cooling medium in the gap accompanying the rotation of the rotor, a spiral groove for forcibly discharging the cooling medium in the gap is formed on the surface of the rotor. .

  Patent Document 3 below describes that the rotor has a concave groove formed on the surface of the cylindrical portion so as to extend in the axial direction in order to reduce drag torque loss due to oil between the rotor and the stator.

JP 2011-125090 A JP 2002-058207 A JP 2001-037129 A

  In a conventional rotating electrical machine, the power loss due to the cooling medium staying in the air gap between the rotor and the stator can be reduced by the cooling medium discharge groove formed on the outer peripheral surface of the cylindrical portion of the rotor.

  By the way, when a rotating electrical machine is used at a low temperature, the viscosity of the cooling medium is higher than that at room temperature, so that there is a problem that the power loss increases and the cooling medium fluid speed decreases and the cooling efficiency decreases. . Although it is conceivable to reduce the power loss by the cooling medium discharge groove as described above, as long as the temperature of the cooling medium does not rise, the increase in the fluid velocity is still not expected, and the cooling efficiency remains lowered.

  An object of the present invention is to provide a rotating electrical machine that can warm up a cooling medium at an early stage and improve the cooling efficiency of the rotating electrical machine with a simple configuration.

  The present invention relates to a rotating electrical machine including a rotor shaft having a flow path through which a cooling medium flows, a rotor fixed to the rotor shaft, and a stator disposed around the rotor via an air gap. End plates provided at both ends in the direction, and the flow path of the rotor shaft supplies a cooling medium to the end surface of the end plate, and the end surface is curved to the inner side of the rotor on the outer side in the radial direction than on the inner side in the radial direction. It is formed so that it may do.

  Moreover, it is preferable that the curve formed in the said end surface is S-shaped in the cross section containing an axis.

  The rotor has a groove for discharging the cooling medium staying in the air gap to the outside, and the groove has a cylindrical portion so as to guide the cooling medium introduced through the end face toward the end plate on the opposite side. It is preferable that the outer peripheral surface is formed in a spiral shape.

  According to the rotating electrical machine of the present invention, with a simple configuration, the cooling medium can be warmed up early and the cooling efficiency of the rotating electrical machine can be improved.

It is a figure which shows the structure of the rotary electric machine of this embodiment. It is a figure which expands and shows the A section of FIG.

  Hereinafter, embodiments of a rotating electrical machine according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of a rotating electrical machine according to the present embodiment, and FIG. 2 is an enlarged view showing a portion A of FIG. In the present embodiment, this configuration will be described by taking a rotating electric machine mounted on an automobile as an example of a prime mover. However, the present invention is not limited to this configuration, and can also be applied to a rotating electrical machine that is used in a cold district or in a situation where the ambient temperature is low. In these figures, the left side is the front of the vehicle, and the right side is the rear of the vehicle.

  The rotating electrical machine 10 is a prime mover of a vehicle. The rotating electrical machine 10 has a rotor 14 fixed to the rotor shaft 12 and a stator 16 fixed to a case (not shown) of the rotating electrical machine 10 so as to surround the rotor 14.

  The rotor 14 is a cylindrical magnetic body concentric with the rotor shaft 12, and is configured by laminating laminated steel plates in the axial direction 18, for example. The rotor 14 has end plates 20 provided at both ends of the laminated laminated steel plates, that is, at both ends in the axial direction 18. A hole extending in the axial direction is formed in the laminated steel plate, and a permanent magnet (not shown) is disposed in this hole. In addition, a permanent magnet can also be arrange | positioned not on the inside of a laminated steel plate but on the outer periphery of a laminated steel plate.

  The rotor shaft 12 is rotatably supported by a bearing (not shown) provided in the case. As will be described later, the rotor shaft 12 is a hollow shaft in which a hole extending in the axial direction 18 is formed. As shown in FIG. 1, the axial direction 18 is the same direction as the vehicle traveling direction. However, the present invention is not limited to this configuration, and may be a direction in which the axial direction 18 intersects the vehicle traveling direction.

  The stator 16 is arranged with an air gap 22 around the rotor 14. The stator 16 has magnetic poles (not shown) that protrude toward the inner peripheral side of the stator 16 and are arranged at a predetermined interval in the circumferential direction. In a slot (not shown) which is a space between the magnetic poles, a coil 24 formed by winding a conductive wire around the magnetic poles is disposed. FIG. 1 shows a coil 24 that bridges between slots, that is, a coil end, at both ends of the stator 16. When the coil 24 is energized, a rotating magnetic field is generated in the stator 16, and a force attracted by the rotating magnetic field is generated in the rotor 14 having a permanent magnet, so that the rotor 14 rotates.

  Generally, a rotating electrical machine generates heat by driving the rotating electrical machine. When the rotating electrical machine is a permanent magnet type rotating electrical machine, the permanent magnet provided in the rotor or the coil of the stator generates heat. When these generate heat and the temperature rises, the operating efficiency of the rotating electrical machine decreases. In order to prevent this reduction in operating efficiency, the rotating electrical machine 10 is cooled by a cooling medium, for example, lubricating oil (ATF), in the vehicle of this embodiment. The cooling structure will be described below.

  A pump (not shown) that circulates the cooling medium is accommodated in the case. This pump is configured to rotate in synchronization with the rotation of the rotor shaft 12. In addition, this invention is not limited to this structure, The electric pump which a pump drives with a dedicated motor may be sufficient.

  As described above, a hole is formed in the rotor shaft 12 along the axial direction 18. This hole is a flow path 26 through which the cooling medium sent out from the pump flows. The flow path 26 includes a branch path 26 a that branches in the radial direction and extends to the outer peripheral surface of the rotor shaft 12. The branch paths 26 a are formed so that the cooling medium is supplied to the end surfaces 20 a of the end plates 20. Although the number of branch paths 26a in FIG. 1 is one for each end plate 20, this number is an example, and the present invention is not limited to the number of branch paths 26a. It is preferable to provide a plurality of branch paths 26a at intervals in the circumferential direction on the same circumference. With this configuration, since the flow rate of the cooling medium increases, the cooling performance for the rotating electrical machine 10 can be improved.

  The configuration of the end surface 20a of the end plate 20 in the present embodiment will be described. As shown in FIG. 2, the end surface 20 a is formed so as to be curved toward the inner side of the rotor 14 on the outer side in the radial direction than on the inner side in the radial direction.

  Due to the shape of the end surface 20a, only a low-temperature cooling medium having a lower viscosity than that at normal temperature is transmitted to the outer peripheral end along the end surface 20a by surface tension, and is introduced into the air gap 22 between the rotor 14 and the stator 16, It is possible to warm up by drag friction there.

  On the other hand, since the surface tension of the cooling medium having a higher viscosity than that at the low temperature is lower than that at the low temperature, the medium is scattered toward the outside in the radial direction before being transmitted to the outer peripheral end of the end face 20a. Specifically, the cooling medium scatters radially outward at the curvature 28. Thereby, the coil end 24 located in the scattering direction of the cooling medium is effectively cooled.

  It is preferable that the curve 28 formed on the end surface 20a of the end plate 20 is formed so as to gradually go to the inner side of the rotor as it goes to the outer side in the radial direction. Specifically, the curvature 28 is preferably S-shaped in a cross section including the axis 18. With this shape, the cooling medium at a low temperature can be effectively guided to the air gap, and the cooling medium at a low temperature or more can be effectively guided to the coil end 24.

  Further, the rotor 14 of the present embodiment has a groove 30 formed on the outer peripheral surface of the cylindrical portion. The groove 30 is formed in a spiral shape on the outer peripheral surface of the cylindrical portion so as to guide the cooling medium introduced through the end surface 20a toward the end plate 20 on the opposite side (the vehicle front side in the drawing). That is, in the present embodiment, the groove 30 is formed in a spiral shape in the direction opposite to the rotation direction of the rotor 14 from the rear to the front of the vehicle. With this configuration, when the rotor 14 rotates, the cooling medium staying in the air gap 22 can be efficiently discharged through the groove 30 to the outside of the air gap 22.

  Next, the operation of the above configuration will be described with reference to FIG. First, the case where the cooling medium is at a high temperature will be described. In this case, the cooling medium has a high viscosity. The cooling medium supplied from the flow path 26 to the end surface 20a passes through the route indicated by the arrow 1 in FIG. That is, the centrifugal force acting on the cooling medium increases along the end surface 20a toward the outer peripheral end, and when the force becomes larger than the surface tension, the end surface 20a is separated from the region curved toward the inside of the rotor 14 in the radial direction. Spatter to the outside. The scattered cooling medium cools the coil 24.

  Next, the case where the cooling medium is at an intermediate temperature lower than the high temperature will be described. In this case, the cooling medium has a medium viscosity that is lower than the high viscosity. The cooling medium supplied from the flow path 26 to the end surface 20a passes through the route indicated by the arrow 2 in FIG. That is, the centrifugal force acting on the cooling medium increases along the end surface 20a toward the outer peripheral end, and when the force exceeds the surface tension, the centrifugal force separates from the end surface 20a and scatters radially outward. This scattering point is a curved region 28 on the outer side in the radial direction than the high temperature. The scattered cooling medium cools the coil 24.

  Finally, the case where the cooling medium is at a low temperature lower than the medium temperature will be described. In this case, the cooling medium has a low viscosity lower than the medium viscosity. The cooling medium supplied from the flow path 26 to the end face 20a passes through the route indicated by the arrow 3 in FIG. That is, the centrifugal force acting on the cooling medium increases as it goes toward the outer peripheral end along the end surface 20a. However, since the surface tension is larger than the centrifugal force up to the outer peripheral end of the end surface 20a, the cooling medium is directly guided to the air gap 22 through the curved region 28 of the end surface 20a. The cooling medium is warmed in the air gap 22 and is discharged from the air gap 22 through the groove 30.

  According to the rotating electrical machine 10 of the present embodiment, the cooling medium in a low temperature state can be efficiently warmed up, and as a result, the cooling efficiency of the rotating electrical machine 10 can be improved.

  In the present embodiment, the case where the curve 28 is formed on the end surface 20a of the end plate 20 on the vehicle rear side as shown in FIG. 2 has been described, but the present invention is not limited to this configuration. What is necessary is just to form in the end surface 20a of one end plate 20, and the vehicle front side may be sufficient. In this case, the groove 30 of the rotor 14 is formed so that the cooling medium staying in the air gap 22 is discharged toward the vehicle rear side.

  In the present embodiment, the case where the rotating electrical machine 10 is a permanent magnet type motor has been described. However, the present invention is not limited to this configuration, and the rotating electrical machine 10 may be of another type, for example, an induction winding type or a reluctance type. May be.

  DESCRIPTION OF SYMBOLS 10 Rotating electrical machine, 12 Rotor shaft, 14 Rotor, 16 Stator, 18 Axial direction, 20 End plate, 22 Air gap, 24 Coil, 26 Flow path, 28 Curve, 30 Groove.

Claims (3)

A rotor shaft having a flow path through which a cooling medium flows;
A rotor fixed to the rotor shaft;
A stator arranged around the rotor via an air gap;
In a rotating electrical machine comprising:
The rotor has end plates provided at both ends in the axial direction,
The flow path of the rotor shaft supplies a cooling medium to the end face of the end plate,
The end face is formed so as to be curved toward the rotor inner side in the radial direction than in the radial direction.
Rotating electric machine characterized by that. In the rotating electrical machine according to claim 1,
The curvature formed on the end surface is S-shaped in a cross section including the axis.
Rotating electric machine characterized by that. In the rotating electrical machine according to claim 1 or 2,
The rotor has a groove for discharging the cooling medium staying in the air gap to the outside,
The groove is formed in a spiral shape on the outer peripheral surface of the cylindrical portion so as to guide the cooling medium introduced through the end surface toward the end plate on the opposite side.
Rotating electric machine characterized by that.

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