JP2014225969A - Electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric motor equipped with a cooling oil passage formed by a simple structure.SOLUTION: An electric motor is provided with a center housing 10, and a side housing 30. A position on which a left side joint surface 15 of the center housing 10 and a joint surface 32 of the side housing 30 abut, is superimposed with a coil end 14 when viewed from a diametrical direction orthogonal to a rotation axis direction. On the left side joint surface 15 of the center housing 10, a hole and a groove 17 abutting to configure a cooling oil passage is formed. The hole has a supply hole 20 extending in an axial direction, and the groove 17 has a distribution groove 18 extending in a circumferential direction, and a plurality of notches 19 notching a wall portion 21 on an inner peripheral side facing the distribution groove 18. Cooling oil is dropped from the plurality of notches 19 to the coil end 14.

Description

  The present invention relates to an electric motor, and more particularly to a cooling structure for supplying cooling oil to a stator.

In a general electric motor, cooling oil is supplied to the coil end of the stator to cool the stator. The coil end refers to a folded portion of the stator coil protruding from the axial end of the stator core, and has an annular shape when viewed from the axial direction.
In recent years, as shown in Patent Documents 1 and 2 below, various techniques have been proposed for a cooling oil passage that supplies cooling oil to a coil end.

  Patent Document 1 below proposes a cooling oil passage that is configured by providing an electric motor with a cooling pipe that extends in the axial direction and an oil guide that disperses cooling oil in the circumferential direction and drops oil.

In the following Patent Document 2, a housing for housing the rotor and the stator is cut by a cutting tool such as an end mill, and a coolant supply port for supplying cooling oil to the coil end, and the coolant supply port It has been proposed to form a cooling liquid passage for circulating the cooling oil.
The coolant supply port disclosed in the cited document 2 is for supplying cooling oil to the coil end, and is formed by cutting the inner peripheral surface of the housing toward the radially outer side. .
In addition, in Cited Document 2, the dimension of the coolant supply port is managed by press-fitting the divided member into the inner peripheral side notch formed by cutting the inner peripheral surface of the housing toward the radially outer side. It has been proposed.

JP 2011-78148 A JP 2007-20323 A

However, in the above-described conventional technology, a cooling pipe, an oil guide, or a divided member is required, so that the number of parts increases. This increase in the number of parts is not preferable because it causes the disadvantage of increasing the size and weight of the motor and also increases the number of manufacturing steps of the motor.
Further, as disclosed in Patent Document 2, cutting from the inner peripheral surface of the housing to the radially outer side requires a high degree of processing work, while the shape of the cooling oil passage is technically limited. This is not preferable.
From the above, it has been desired that the cooling oil passage can be formed with a simple structure.

  Therefore, the present invention is an invention created in view of the background described above, and an object thereof is to provide an electric motor including a cooling oil passage formed by a simple structure.

  As means for solving the above-described problems, an electric motor according to the present invention includes a substantially cylindrical center housing having a stator fixed on the inner peripheral side and having an opening in the rotation axis direction of the rotor, and closing the opening of the center housing. And a side housing that forms a motor chamber in which the stator and the rotor are accommodated together with the center housing, wherein the mating surface of the center housing and the mating surface of the side housing are in contact with each other. The position overlaps with the coil end of the stator as viewed from the radial direction orthogonal to the rotational axis direction, and cooling is achieved by contacting the at least one of the mating surface of the center housing and the mating surface of the side housing. A hole and a groove constituting the oil passage are formed, the hole extends in the direction of the rotation axis, and the coil end A supply hole through which cooling oil flows, the groove being continuous with the supply hole, a distribution groove extending in the circumferential direction, and an inner peripheral wall facing the distribution groove A plurality of cutouts for communicating the distribution groove and the motor chamber, and the cooling oil is dropped from the plurality of cutouts to the coil end.

According to the present invention described above, the portion where the hole and the groove are formed is a mating surface of the housing (center housing and side housing) that is relatively easy to process. For this reason, in the present invention, it is not necessary to perform advanced machining operations as described in the related art regarding the formation of holes and grooves.
Further, when the mating surface of the center housing and the mating surface of the side housing come into contact with each other, the holes and grooves formed in the mating surface constitute the following cooling oil passage.
For example, the groove formed and opened on the mating surface of the center housing becomes a closed space covered with the mating surface of the side housing that comes into contact, and the cooling oil can flow along the shape of the groove.
Alternatively, for example, the hole or groove formed in the mating surface of the center housing can supply cooling oil to the hole or groove of the side housing that comes into contact, and the cooling oil can flow between different members.
Therefore, according to the present invention, the cooling oil passage is formed by forming the hole and the groove and bringing the mating surface of the center housing and the mating surface of the side housing into contact with each other. There is no need to provide an oil passage for cooling, and an increase in the number of parts can be prevented.
Furthermore, the cooling oil passage according to the present invention is as follows.
First, when cooling oil is supplied to the supply hole, it flows in the direction of the rotation axis and is supplied to a distribution groove continuous to the supply hole. The cooling oil supplied to the distribution groove flows in the circumferential direction along the inner peripheral wall facing the distribution groove. Further, the cooling oil falls from a notch that cuts out the inner peripheral wall facing the distribution groove. The position where the mating surface of the center housing and the mating surface of the side housing come into contact with the coil end when viewed from the radial direction orthogonal to the rotation axis direction overlaps with the coil end, so that the cooling dropped from the notch on the upper surface of the coil end Oil is supplied.
Furthermore, the cooling oil flows in the circumferential direction (downward) along the shape of the coil end, so that the cooling oil is supplied to the entire coil end and the stator is cooled.
As described above, according to the present invention, the cooling oil passage having a relatively simple structure is provided, and the stator can be cooled by the cooling oil passage.

  The inner circumferential wall facing the distribution groove is provided with a plurality of ribs projecting upward on the downstream side of each of the plurality of notches, and each of the plurality of ribs projects upward. It is preferable that the protruding amounts to be different are different.

According to the above-described configuration, the cooling oil that flows along the inner peripheral wall is held by the rib, and a predetermined amount of the cooling oil is stored. Therefore, even if the supply of cooling oil is temporarily stopped, the stored cooling oil can be supplied to continue cooling the stator.
Further, according to the configuration described above, the amount of cooling oil stored by being held by each rib can be adjusted by changing the amount of protrusion of each of the plurality of ribs.
Therefore, by increasing the protruding amount of the rib on the downstream side with respect to the notch where oil droplets drop at a location where the amount of heat is large at the coil end, a large amount of cooling oil is supplied to the location where the amount of heat is large, and the stator is efficiently Can be cooled.

  ADVANTAGE OF THE INVENTION According to this invention, the electric motor provided with the cooling oil path formed by the simple structure can be provided.

It is sectional drawing which looked at the cross section (cross section cut in the AA line of FIG. 2) of the electric motor which concerns on embodiment incorporated in the power plant from the front side. It is the right view seen from the center housing and the stator and the right side. It is the enlarged view to which a part of groove | channel formed in the right mating surface of a center housing was expanded.

An embodiment of an electric motor according to the present invention will be described with reference to FIGS.
In the embodiment, an example in which an electric motor is incorporated in a power unit used as a power unit of an electric vehicle will be described.

The power unit 1 is a drive source that is mounted on an electric vehicle and converts electric power into rotational force, transmits the converted rotational force to driving wheels, and drives the electric vehicle.
As shown in FIG. 1, the power unit 1 includes an electric motor 3 having a rotor shaft 2 extending in the left-right direction, and a gear box 4 disposed on the left side of the electric motor 3.
In the power unit 1 according to the embodiment, the center housing 10 constituting the electric motor 3 and the gear housing 5 constituting the gear box 4 are fastened by bolts (not shown), and the electric motor 3 and the gear box 4 are integrated. ing. The gear housing 5 according to the present embodiment has a configuration corresponding to a “side housing” described in the claims.

Although not shown, the gear box 4 has a speed change mechanism including a large number of gears, and reduces the rotational speed of the rotor shaft 2 to transmit the power of the electric motor 3 to the drive shaft.
Further, the gear box 4 includes an oil passage for supplying lubricating oil to a large number of gears and a circulation pump (not shown).

The gear housing 5 constituting the gear box 4 is a box-shaped casting manufactured by die casting.
As shown in FIG. 1, in the present embodiment, since the gear housing 5 and the center housing 10 are fastened by bolts, the right wall portion 5 a of the gear housing 5 closes the left opening of the center housing 10.
An annular ball bearing 5b is provided on the right wall portion 5a of the gear housing 5, and the ball bearing 5b rotatably supports the left end portion of the rotor shaft 2.
An input shaft of a transmission mechanism (not shown) is connected to the left end portion of the rotor shaft 2 so that the rotational motion of the rotor shaft 2 is transmitted to the transmission mechanism.

  Furthermore, a substantially annular ring portion 6 that protrudes to the right is formed on the right wall portion 5 a of the gear housing 5, and a right end surface 6 d (hereinafter referred to as “mating surface”) of the annular portion 6 is formed. The center housing 10 is in contact with the left mating surface 16. Note that the amount of protrusion by which the mating surface 6d of the annular portion 6 protrudes to the right side is such that it overlaps the left coil end 14 to be described later of the electric motor 3 when viewed from the radial direction orthogonal to the rotor shaft 2 (rotating shaft). ing.

Further, an oil forward path 6a (see arrow B in FIG. 1) is formed in the upper part of the annular part 6, and an oil return path 6b (see arrow C in FIG. 1) is formed in the lower part of the annular part 6. Yes.
The oil forward path 6 a and the oil return path 6 b are holes formed in the mating surface 6 d of the annular portion 6, and are connected to an oil path (not shown) in the gear housing 5. Therefore, the lubricating oil in the gear box 4 is supplied as cooling oil to the electric motor 3 via the oil forward path 6a, and the cooling oil can be recovered via the oil return path 6b. In addition, the oil forward path 6a and the oil return path 6b in the present embodiment are configurations corresponding to “supply holes” described in the claims.

Next, the electric motor 3 will be described.
The electric motor 3 is for converting electric energy into the rotational motion of the rotor shaft 2. The electric motor 3 includes a rotor shaft 2, an annular center housing 10 fixed to the gear housing 5, a substantially cylindrical rotor 11 fixed to the outer periphery of the rotor shaft 2, and an inner peripheral surface 10 a of the center housing 10. A stator 12 that is fixed and surrounds the outer periphery of the rotor 11 and a substantially disk-shaped side housing 30 that is disposed on the right side of the center housing 10 are provided.

  Although not shown, the rotor 11 includes a plurality of steel plates fixed to the rotor shaft 2 and permanent magnets provided between the plurality of steel plates, and is rotated by a rotating magnetic field generated by the stator 12.

  As shown in FIG. 1, the stator 12 is press-fitted on the inner peripheral side of the center housing 10. The stator 12 includes a stator core 12a in which a plurality of steel plates are arranged in the circumferential direction along the inner peripheral surface 10a of the center housing 10, a stator coil 12b wound around the stator core 12a, and a stator core 12a on the inner peripheral surface. And an annular fixing ring (not shown) to which is fixed.

The folded portion of the stator coil 12b protrudes in the left-right direction from the axial end of the stator core 12a to form a coil end 14.
Further, as shown in FIG. 2, when viewed from the axial direction, the coil end 14 has a substantially annular shape, and when cooling oil is dropped from above, the coil end 14 has an arcuate shape. It adheres to the upper surface and flows between the coils and also flows downward along the outer periphery of the coil end 14 so that the cooling oil flows throughout the coil end.

  As shown in FIG. 1, the center housing 10 is a substantially cylindrical member that is open in the left-right direction, and is a casting manufactured by die casting. The left and right openings of the center housing 10 are closed by the right wall portion 5a of the gear housing 5 and the side housing 30, and the inside of the center housing 10 defines a motor chamber R that houses the rotor 11 and the stator 12. It is composed.

  As shown in FIG. 2, the center housing 10 has an annular inner peripheral portion 10b into which the stator 12 is press-fitted and an annular outer peripheral portion 10c (see FIG. 2) surrounding the outer periphery of the inner peripheral portion 10b when viewed from the axial direction. 2).

As shown in FIG. 1, the outer peripheral part 10c protrudes in the left-right direction rather than the inner peripheral part 10b.
The amount of protrusion of the outer peripheral portion 10c in the left-right direction is such that the left and right end faces (mating surfaces) of the outer peripheral portion 10c overlap the coil end 14 when viewed from the radial direction orthogonal to the rotor shaft 2 (rotating shaft). It has become.
For this reason, the positions where the left and right end faces (mating surfaces) of the outer peripheral portion 10c abut on the mating surface 6d of the gear housing 5 and the mating surface 32 of the side housing 30 are diameters orthogonal to the rotor shaft 2 (rotating shaft). When viewed from the direction, it overlaps the coil end 14.
In the following description, an end surface facing the right side in the outer peripheral portion 10c is referred to as a right mating surface 15, and an end surface facing the left side is referred to as a left mating surface 16.

As shown in FIG. 2, a supply hole 20 and a groove 17 are formed in the right mating surface 15.
As shown in FIG. 1, the supply hole 20 is a substantially straight hole extending in the left-right direction and penetrating the right mating surface 15 and the left mating surface 16, and when the center housing 10 is cast, the supply hole 20. It is formed by using a core equivalent in shape.
In addition, although the example which formed using the core about the supply hole 20 which concerns on embodiment was given and demonstrated, the formation direction of the supply hole 20 of this invention is not limited to this. For example, it may be formed by cutting in the left-right direction, and even the cutting can be formed relatively easily.

The left end portion of the supply hole 20 is connected to the oil forward path 6 a of the gear housing 5. Therefore, the cooling oil in the gear box 4 is allowed to flow to the right side of the center housing 10 so that the members and parts disposed on the right side of the center housing 10 can be cooled.
Further, the supply hole 20 is formed on the upper side of the center housing 10 and is located above the coil end 14. Therefore, the cooling oil can be supplied to the right coil end 14 from above.

  As shown in FIG. 3, the groove 17 includes a substantially circular distribution groove 18 formed on the upper side of the right mating surface 15 and a plurality of cuts penetrating the inner wall 21 facing the distribution groove 18. And a notch 19.

The distribution groove 18 is a groove extending in the circumferential direction, and an inner peripheral wall 21 facing the distribution groove 18 bends downward from the central portion in the front-rear direction to form a gently curved surface. Therefore, the cooling oil that has flowed out of the supply hole 20 into the distribution groove 18 flows in the circumferential direction (front-rear direction) along the wall portion 21.
Note that the distribution groove 18 of the present embodiment is provided below the supply hole 20. Therefore, the distribution groove 18 has a communication groove 18 a that extends upward from the distribution groove 18 and connects the distribution groove 18 and the supply hole 20. According to this, as shown by an arrow E shown in FIG. 3, the cooling oil flowing through the supply hole 20 flows into the distribution groove 18 from above.

The cutout 19 is a groove extending in the vertical direction by cutting out the inner peripheral wall portion 21, and communicates the distribution groove 18 with the motor chamber R. For this reason, the cooling oil flowing along the wall portion 21 passes through the notch 19 and is dropped into the motor chamber R as indicated by an arrow F shown in FIG.
Further, as described above, when viewed from the radial direction orthogonal to the rotor shaft 2 (rotation axis), the position where the right mating surface 15 of the outer peripheral portion 10c abuts the mating surface 32 of the side housing 30 is the right coil end. 14 and overlap. Therefore, the cooling oil dropped through the notch 19 and dropped into the motor chamber R is supplied to the upper surface of the right coil end 14.
The cooling oil supplied to the upper surface of the right coil end 14 flows in the circumferential direction along the outer periphery of the coil end 14 as indicated by the arrow G shown in FIG. It is like that.

Here, as shown in FIG. 2, the cooling oil dropped downward from the coil end 14 forms an oil reservoir P on the lower side of the motor chamber R. The oil reservoir P is immersed in the lower side of the coil end 14 to further cool the coil end 14.
In addition to the coil end 14, the lower part of the inner peripheral portion 10 b of the center housing 10 is immersed in the oil reservoir P.

In addition, a plurality of ribs 22 projecting upward are provided on the inner peripheral wall portion 21 at positions downstream of the notches 19 corresponding to the notches 19.
According to this, the cooling oil flowing along the wall portion 21 on the inner peripheral side is blocked by the ribs 22, and a predetermined amount of the cooling oil is stored. Therefore, even when the supply of the cooling oil is temporarily stopped, the stored cooling oil can continue the oil droplets from the notch 19.

Here, the amount of cooling oil supplied to the coil end 14 can be adjusted by changing the size of the notch 19, and the amount of protrusion of each of the plurality of ribs 22 can be changed to change each rib 22. It is possible to adjust the amount of cooling oil that is retained and stored.
Therefore, by increasing the notch 19 in which oil drops in the coil end 14 have a large amount of heat, and by increasing the protruding amount of the rib 22 on the downstream side of the large notch 19, A large amount of cooling oil can be supplied, and the stator 12 can be efficiently cooled.

  In addition, although the groove | channel 17 which concerns on embodiment is shape | molded by forming the convex part of the same diameter row as the shape of the groove | channel 17 in the metal mold | die which casts the center housing 10, this invention is limited to this. However, it may be formed by cutting, and even the cutting can be formed relatively easily.

  In addition, as shown in FIG. 2, a plurality of fixing holes 10 f for screwing bolts for fixing the side housing 30 are formed in the right mating surface 15 at intervals in the circumferential direction.

Next, the left mating surface 16 of the center housing 10 will be described with reference to FIG. As described above, the supply hole 20 passes through the left mating surface 16.
Further, although not shown, a groove extending in the circumferential direction from the supply hole 20 (a groove having the same shape as the distribution groove 18) is formed on the left mating surface 16.
A plurality of grooves 16a (grooves having the same shape as the notches 19; only one is shown in FIG. 1) penetrating downward from the grooves extending in the circumferential direction are formed.
Further, as described above, when viewed from the radial direction orthogonal to the rotor shaft 2 (rotation axis), the position where the left mating surface 16 of the outer peripheral portion 10c abuts the mating surface 6d of the gear housing 5 is the left coil end. 14, the cooling oil dropped into the motor chamber R through the groove 16 a is supplied to the upper surface of the left coil end 14.

Next, the inner peripheral part 10b of the center housing 10 will be described.
As shown in FIG. 2, the inner circumferential portion 10 b is formed with a communication hole 25 penetrating in the left-right direction on the lower side immersed in the oil sump P.
As shown in FIG. 1, the communication hole 25 corresponds to the oil return path 6 b formed in the annular portion 6 of the gear housing 5, and the cooling oil accumulated in the lower side of the motor chamber R communicates with the communication hole 25. The gear housing 5 is collected through the hole 25.
A substantially annular cooling water passage 26 is formed inside the inner peripheral portion 10b, and the stator core 12a fixed to the inner peripheral side of the inner peripheral portion 10b can be cooled.

Next, the side housing 30 will be described.
The side housing 30 is a substantially disk-shaped casting manufactured by die casting.
The side housing 30 is fixed to the right side of the center housing 10 by being fastened to a bolt that is screwed into the fixing hole 10f, and closes the opening on the right side of the center housing 10.
An annular ball bearing 31 is provided at the center of the side housing 30, and the ball bearing 31 rotatably supports the right end portion of the rotor shaft 2.

A mating surface 32 that protrudes to the left and contacts the right mating surface 15 of the center housing 10 is formed on the outer peripheral side of the left side surface of the side housing 30.
A groove 37 is formed in the mating surface 32 of the side housing 30.
The groove 37 is formed with a distribution groove 38 having the same shape as the distribution groove 18 (see FIG. 3) formed on the right mating surface 15 of the opposite center housing 10.
A rib 39 protruding upward is formed in the groove 37 corresponding to the rib 22 (see FIG. 3) formed on the right mating surface 15 of the center housing 10.
Therefore, the cooling oil flowing into the distribution groove 18 also flows out into the distribution groove 38 of the side housing 30 and is stored by the ribs 39.
According to this, compared with the case where the groove | channel 37 is not formed in the mating surface 32 of the side housing 30, it becomes possible to increase the storage amount of the cooling oil.

  Further, a bearing supply oil passage 34 for supplying the cooling oil stored in the groove 37 to the ball bearing 31 is formed in the side housing 30. The cooling oil supplied to the ball bearing 31 passes through the ball bearing 31 and flows into the motor chamber R, and joins the oil sump P.

As described above, according to the electric motor 3 according to the embodiment, the holes (the oil forward path 6a, the oil return path 6b, the supply hole 20) and the grooves 17, 37 (the distribution groove 18, the notch 19, the distribution groove 38) are arranged in the housing ( The gear housing 5, the center housing 10, and the side housing 30) are formed.
However, the portions where the holes and the grooves 17 and 37 are formed are the mating surfaces (6b, 15, 16, and 32) of the housing and can be formed relatively easily. Therefore, advanced machining operations such as cutting from the inner peripheral surface of the housing toward the radially outer side as described in the related art are unnecessary.
Further, according to the electric motor 3 according to the embodiment, holes (oil forward path 6a, oil return path 6b, supply hole 20) formed in the mating surface of the housing, and grooves 17, 37 (distribution groove 18, notch 19, distribution) The groove 38) forms a continuous cooling oil passage by the contact of the mating surfaces (6b, 15, 16, 32) of the housing. For this reason, it is not necessary to provide a separate component and install a cooling oil passage, thereby preventing an increase in the number of components.
As described above, according to the electric motor 3 according to the embodiment, the stator can be cooled by the cooling oil passage formed with a relatively simple structure.

Although the electric motor 3 according to the embodiment has been described above, the present invention is not limited to the example described in the embodiment.
For example, although the electric motor 3 according to the embodiment is incorporated so as to be integrated with the gear box 4, the electric motor 3 may be a single unit. In addition, the cooling oil is supplied from the gear box 4 to the electric motor 3, but it may be supplied from another device.

  In the embodiment, holes or grooves are formed in all of the abutting surfaces (the left and right mating surfaces 16 and 15 of the center housing 10, the mating surface 6d of the gear housing 5, and the mating surface 32 of the side housing 30). However, the present invention is not limited to this. It is only necessary to be formed on at least one of the abutting mating surfaces.

DESCRIPTION OF SYMBOLS 1 Power unit 3 Electric motor 5 Gear housing 6 Ring part 10 Center housing 11 Rotor 12 Stator 14 Coil end 17 Groove 18 Distribution groove 19 Notch 20 Supply hole (hole)
22 Rib 25 Communication hole 30 Side housing

Claims (2)

A substantially cylindrical center housing having a stator fixed to the inner peripheral side and having an opening in the rotation axis direction of the rotor;
A side housing that closes an opening of the center housing and forms a motor chamber in which the stator and the rotor are housed together with the center housing;
An electric motor with
The position where the mating surface of the center housing and the mating surface of the side housing are in contact with the coil end of the stator when viewed from the radial direction orthogonal to the rotational axis direction,
At least one of the mating surface of the center housing and the mating surface of the side housing is formed with a hole and a groove forming a cooling oil passage by the contact,
The hole has a supply hole that extends in the direction of the rotation axis and is disposed above the coil end and through which cooling oil flows.
The groove is
A distribution groove that is continuous with the supply hole and extends in the circumferential direction;
A plurality of notches communicating the distribution groove and the motor chamber by notching an inner peripheral wall facing the distribution groove;
The motor is characterized in that the cooling oil drops into the coil end from the plurality of notches. A plurality of ribs projecting upward are provided on the downstream side of each of the plurality of notches on the inner peripheral wall facing the distribution groove,
The electric motor according to claim 1, wherein each of the plurality of ribs has a different amount of protrusion protruding upward.

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