WO2020109832A1

WO2020109832A1 - Electric motor unit

Info

Publication number: WO2020109832A1
Application number: PCT/IB2018/001477
Authority: WO
Inventors: 朝倉大輔; カリムミカティ
Original assignee: 日産自動車株式会社; ルノーエス．ア．エス．
Priority date: 2018-11-27
Filing date: 2018-11-27
Publication date: 2020-06-04

Abstract

This electric motor unit is provided with: a stator; a case for housing the stator; a rotating shaft rotatably supported in the case; a rotor supported on the rotating shaft in a stationary manner; a cooling device for injecting a cooling liquid toward the stator; a ventilation path penetrating from the inner wall surface of the case to the outer wall surface thereof; and a pressure adjusting device having a respiration film allowing air to pass and connected to the opening portion of the ventilation path on the outer wall surface side. The electric motor unit is further provided with a barrier formed as a part of the case or a part of the stator between the supply opening of the cooling device and the opening portion of the ventilation path on the inner wall surface side.

Description

Electric motor unit

The present invention relates to an electric motor unit.

It is known that a waterproof box-shaped case used for devices such as electric motors and transmissions is provided with a breathing film made of a synthetic resin such as PTFE in order to reduce the pressure difference between the inside and outside of the case. ing. It is also known to cool components housed in a case with a cooling liquid.

By the way, when cooling with a cooling liquid, if the respiratory film is impregnated with the cooling liquid, there is a problem that the breathability of the respiratory film is reduced and the pressure difference cannot be alleviated. JP2017-125536A discloses a structure in which the opening of the passage communicating with the respiratory membrane is covered with a cover formed of a member different from the case in order to prevent the cooling liquid from adhering to the respiratory membrane.

However, in the configuration described in the above document, the problem that the number of parts increases and the cost increases by forming the cover with another member, and further, the case is prevented from increasing in size to secure a space for attaching the cover. There is a problem that there is no.

Therefore, the present invention aims to suppress the impregnation of the cooling fluid into the respiratory membrane without causing the above-mentioned problems.

An electric motor unit according to an aspect of the present invention includes a stator, a case accommodating the stator, a rotating shaft rotatably supported by the case, a rotor fixedly supported by the rotating shaft, and a cooling liquid directed toward the stator. A cooling device for jetting, a ventilation path penetrating from an inner wall surface to an outer wall surface of the case, and a pressure adjusting device having a breathing film that allows passage of air and connected to an outer wall surface side opening portion of the ventilation path. .. Further, the electric motor unit includes a barrier formed as a part of the case or a part of the stator between the supply port of the cooling device and the inner wall surface side opening of the ventilation path.

FIG. 1 is an exploded perspective view of the electric motor unit according to the first embodiment. FIG. 2 is a cross-sectional view of the electric motor unit according to the first embodiment as seen from the rotation axis direction. FIG. 3 is a diagram for explaining the flow of the cooling liquid. FIG. 4 is a cross-sectional view of the electric motor unit according to the second embodiment as seen from the rotation axis direction.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is an exploded perspective view of an electric motor unit according to this embodiment. FIG. 2 is a cross-sectional view of the electric motor unit of FIG. 1 seen from the axial direction of the rotary shaft 4 (Y-axis direction of FIG. 1) described later.

The electric motor unit according to this embodiment is used, for example, as a power source for an electric vehicle or a hybrid vehicle. In the electric motor unit, the Z-axis direction in FIG. 1 is the upward direction in use. In the following description, the direction along the X-axis is the left-right direction, the direction along the Y-axis is the front-back direction, and the direction along the Z-axis is the vertical direction.

As shown in FIG. 1, the electric motor unit includes a stator 2, a case 1 for housing the stator 2, a rotary shaft 4 rotatably supported by the case 1, and a rotor 3 fixedly supported by the rotary shaft 4. A cooling device 5 that injects a cooling liquid toward the stator 2 and a pressure adjusting device 6 that adjusts the pressure inside the case 1 are provided.

The stator 2 includes a stator core 2A made of laminated steel plates, coils (not shown) arranged in slots of the stator core 2A, and a stator holder 2B that holds the stator core 2A from the outer peripheral side. In the present specification, the stator core 2A, the coil, and the stator holder 2B are collectively referred to as the stator 2 unless otherwise specified.

The stator holder 2B has a plurality of bolt holes 7, and the stator 2 is fixed to the case 1 by bolts (not shown) through the plurality of bolt holes 7. The structure around the bolt hole 7 will be described later.

The case 1 is formed in a box shape having a space for housing the stator 2. A cooling device 5 and a pressure adjusting device 6, which will be described later, are attached to the case 1. A cooling liquid reservoir 1A is provided at the bottom of the case 1. The cooling liquid reservoir 1A may be formed integrally with the case 1, or may be formed as a separate member and attached to the case 1. Note that the coolant reservoir 1A is omitted in FIG.

Also, on the side surface of the case 1, there is provided a ventilation passage 8 that penetrates from the inner wall surface to the outer wall surface of the case 1. As shown in FIG. 2, the ventilation passage 8 is provided horizontally with respect to the ground in a use state.

The rotating shaft 4 is rotatably supported by the case 1 via a bearing (not shown). The rotor 3 is fixedly supported on the rotating shaft 4 by a method such as press fitting, and rotates integrally with the rotating shaft 4.

The cooling device 5 is a device for mainly cooling the coil end portion of the stator 2 housed in the case 1. The cooling device 5 is arranged on the upper surface of the case 1 so that the supply port 5A faces the inside of the case at substantially the center in the left-right direction and the center in the front-rear direction, and supplies the cooling liquid vertically downward from the supply port 5A. The position of the upper surface of the case 1 at the approximate center in the left-right direction and the approximate center in the front-rear direction is referred to as a “vertex”.

The cooling liquid is assembled from the cooling liquid reservoir 1A by an oil pump (not shown) and sent to the cooling device 5 via the cooling liquid passage (not shown). The flow of the cooling liquid supplied from the supply port 5A will be described later.

The pressure regulator 6 is connected to the opening of the ventilation passage 8 on the outer wall surface of the case 1 (hereinafter, this opening is referred to as the outer wall surface side opening). The pressure adjusting device 6 has a function of reducing the pressure difference between the inside and the outside of the case 1. Specifically, the pressure regulating device 6 includes a breathing film having a function of allowing air to pass while preventing dust and liquid from passing, and breathes through a passage communicating between the inside and outside of the case 1 when connected to the ventilation passage 8. It is configured to close with a membrane. The breathing membrane is a thin film formed of a synthetic resin (for example, Poly Tetra Fluoro Ethylene: PTFE). Since the pressure adjusting device 6 having such a configuration is publicly known, detailed description thereof will be omitted.

Here, the structure around the bolt hole 7 of the stator 2 will be described.

On the outer circumference of the stator 2, protrusions 2C that project in the radial direction of the stator 2 and extend from the front end to the rear end of the stator holder 2B are provided by the number of bolts for fixing the stator 2 to the case 1. Bolt holes 7 through which fixing bolts are inserted are formed in the protrusions 2C. In this embodiment, since the stator 2 is fixed to the case 1 with four bolts, the protrusions 2C are provided at four places. These four protrusions 2C are arranged at equal intervals in the circumferential direction of the stator 2, and one protrusion 2C is provided on the supply port 5A of the cooling device 5 and the opening of the ventilation passage 8 on the inner wall surface side of the case 1 (hereinafter, this The opening is referred to as an inner wall surface side opening). The projection 2C located between the supply port 5A of the cooling device 5 and the inner wall surface side opening of the ventilation path 8 is also referred to as a barrier 2C.

In the following description, the portion of the outer peripheral surface of the stator 2 from the protrusion 2C that faces the barrier 2C with the supply port 5A in between and the barrier 2 is referred to as the upper surface of the stator 2.

The length of the barrier 2 from the rotation center of the rotation shaft 4 to the most protruding portion (L2 in FIG. 2) is the length from the rotation center of the rotation shaft 4 to the portion that receives the cooling liquid of the stator 2 (L1 in FIG. 2). ) Longer. Here, the most protruding portion is a portion of the barrier 2 that is farthest from the rotation center of the rotation shaft 4. The portion of the stator 2 that receives the cooling liquid is the portion that faces the supply port 5A.

Next, the flow of the cooling liquid will be described with reference to FIG.

FIG. 3 is a perspective view of the stator 2, the rotor 3, and the rotating shaft 4. Thick line arrows in the figure indicate the flow of the cooling liquid. Further, P in the figure indicates a portion that receives the above-described cooling liquid.

The cooling liquid is sprayed from the supply port 5A of the cooling device 5 arranged at the apex of the case 1 toward the stator 2, and collides with the portion P of the stator 2 that receives the cooling liquid. The cooling liquid that has collided with the portion P radially disperses and flows on the outer peripheral surface of the stator 2, and a part of the cooling liquid reaches the respective end portions of the stator 2 in the front-rear direction as they are, and the coil ends that become hot by operating Cooling.

On the other hand, the cooling liquid that has collided with the barrier 2C before reaching each end of the stator 2 in the front-rear direction is accumulated in the reservoir 9 defined by the wall surface of the barrier 2C on the supply port 5A side and the upper surface of the stator 2. .. Since the end portion in the front-rear direction of the stator 2 which is indicated by the broken line in FIG. 3 is open, the cooling liquid accumulated in the reservoir portion 9 flows in the front-rear direction of the stator 2 along the barrier 2C, and the coil ends. To cool. The cooling liquid that has collided with the projection 2C facing the barrier 2C with the supply port 5A interposed therebetween also flows along the projection 2C and cools the coil ends, as in the above.

The cooling liquid that has cooled the coil end is collected in the cooling liquid reservoir 1A below the case 1.

Note that the volume of the reservoir 9 is set to a size such that even if the cooling liquid is continuously jetted from the supply port 5A, the cooling liquid does not get over the barrier 2C and overflow into the ventilation passage 8. In other words, the amount of protrusion of the barrier 2C is set so that the cooling liquid does not get over the reservoir 9.

Next, the effect of providing the barrier 2C will be described.

Without the barrier 2C, a part of the flow having the circumferential component of the cooling liquid approaches the ventilation passage 8 along the outer peripheral surface of the stator 2. Then, a part of the cooling liquid that has approached the ventilation passage 8 may be scattered as droplets due to the vibration of the operating electric motor unit or the vibration of the vehicle and enter the ventilation passage 8. Further, if the barrier 2C is not provided, there is a possibility that the cooling liquid that has been ejected from the supply port 5A and collided with the stator 2 to become droplets may enter the ventilation passage 8.

When the cooling liquid repeatedly enters the air passage 8, the cooling liquid is accumulated in the air passage 8, and eventually the breathing film of the pressure regulator 6 is impregnated with the cooling liquid and the breathability of the breathing film is lowered. , The pressure regulating function is deteriorated.

On the other hand, when the barrier 2C is provided as in the present embodiment, the flow of the cooling liquid becomes as described above, so that the entry of the cooling liquid into the ventilation passage 8 is suppressed, and as a result, the cooling liquid is prevented from entering the breathing membrane. Impregnation can be suppressed.

By the way, as a device for relaxing the pressure difference between the inside and outside of the case, in addition to the pressure regulator 6 of the present embodiment, one end of the hose is connected to the opening provided in the case, and the other end of the hose is opened. There is also a so-called hose type. Since the breathing membrane made of synthetic resin is not used in the hose type, the hose type is often used when the oil is circulated or agitated inside the case. Therefore, also in this embodiment, it seems that the problem of impregnating the breathing film with the cooling liquid does not occur if the hose type is used.

However, in the case of the electric motor unit used as the power source of the vehicle as in the present embodiment, the use of the hose type causes the following problems.

First, it is necessary to fix the open end of the hose at a position where it can prevent water from entering the inside even if the electric motor unit is submerged. Since the electric motor unit is mounted at a relatively low position on the vehicle body, the open end of the hose is fixed to a member different from the electric motor unit. Therefore, the handling of the hose becomes complicated.

Secondly, the electric motor unit swings due to the vibrations of its own operation and the vibrations of the vehicle body, so the distance between the fixed position of the open end of the hose and the fixed position of the hose on the case side changes. And, a long hose is required to cope with the variation in the distance.

Thirdly, the work space around the electric motor unit is limited, so it is difficult to fix the hose.

Fourth, when the electric motor unit is mounted on or near the rear wheel axle to drive the rear wheel, the mounting position of the electric motor unit is below the vehicle body floor. It is difficult to set the position so that it will not be flooded even when submerged.

On the other hand, since the pressure regulator 6 of the present embodiment only needs to be fixed to the case 1, the above problems do not occur.

In the present embodiment, the ventilation path 8 is described as being horizontal with respect to the ground in the use state, but it may be inclined so that the end portion outside the case is higher than the end portion inside the case. .. If the air passage 8 is horizontal or inclined as described above, even if the cooling liquid reaches the inner wall surface side opening portion of the air passage 8, it is difficult to enter the inside of the air passage 8, so that the cooling film is cooled. The possibility of liquid impregnation is reduced.

Next, the effects of this embodiment will be summarized.

The electric motor unit of this embodiment includes a stator 2, a case 1 that houses the stator 2, a rotating shaft 4 that is rotatably supported by the case 1, a rotor 3 that is fixedly supported by the rotating shaft 4, and a stator 2. A cooling device 5 for injecting a cooling liquid toward the air passage, a ventilation passage 8 penetrating from the inner wall surface to the outer wall surface of the case, and a breathing membrane that allows passage of air, and is connected to the outer wall surface side opening portion of the ventilation passage 8. The pressure adjusting device 6 is provided. The electric motor unit is provided with a barrier 2C formed as a part of the stator 2 between the supply port 5A of the cooling device 5 and the inner wall surface side opening of the ventilation path 8. As a result, it is possible to suppress the inflow of the cooling liquid into the ventilation passage 8 and to suppress the impregnation of the breathing film of the pressure adjusting device 6 with the cooling liquid. Further, since the barrier 2C is formed as a part of the stator 2, the number of parts and the cost are not increased.

In this embodiment, the supply port 5A is opened at a position which is the upper surface when the case 1 is in use. Thereby, the coil end of the stator 2 can be cooled by utilizing the flow generated by the self-weight of the cooling liquid.

The barrier 2C of the present embodiment is a protrusion in which a part of the outer circumference of the stator 2 protrudes in the radial direction of the stator 2, and the length L2 from the most protruding portion to the rotation center of the rotation shaft 4 is the rotation of the rotation shaft 4. It is longer than the length L1 from the center to the portion P of the stator 2 that receives the cooling liquid. As a result, the flow of the cooling liquid in the direction of the ventilation passage 8 is blocked by the barrier 2C, so that the cooling liquid can be prevented from entering the ventilation passage 8.

The pressure regulating device 6 of the present embodiment is connected to a ventilation path 8 that communicates the inside and outside of the case 1, and the ventilation path 8 is horizontal to the ground in the use state, or an opening portion on the outer wall surface side rather than an opening portion on the inner wall surface side. Is inclined to be higher. As a result, even if the cooling liquid reaches the opening on the inner wall surface side of the ventilation passage 8, it is difficult for the cooling liquid to enter the inside of the ventilation passage 8, so that the possibility that the respiratory membrane is impregnated with the cooling liquid is reduced.

(Second embodiment)
FIG. 4 is a sectional view of the electric motor unit according to the second embodiment as seen from the axial direction of the rotary shaft 4.

The difference from the electric motor unit according to the first embodiment shown in FIG. 2 is that the barrier 2C of the first embodiment is a part of the stator 2, while the barrier 10 of the present embodiment is one of the cases 1. It is a department. Hereinafter, this difference will be mainly described.

The difference described above occurs because the method of fixing the stator 2 to the case 1 is bolt fixing in the first embodiment, but press fitting in the present embodiment. That is, in the first embodiment, it is necessary to provide the stator 2 with the plurality of bolt holes 7, and one of the plurality of protrusions 2C provided for that purpose is used as the barrier 2C.

On the other hand, in this embodiment, since the stator 2 is fixed to the case 1 by press fitting, it is not necessary to provide the protrusion 2C on the stator 2. However, in order to fix by press fitting, a contact point between the outer wall surface of the stator 2 and the inner wall surface of the case 1 is required. Therefore, the inner wall surface of the case 1 is provided with a plurality of protrusions 10 that protrude radially inward and contact the outer periphery of the stator 2. The contact between the plurality of protrusions 10 and the outer wall surface of the stator 2 is, for example, from one end to the other end of the stator holder 2B in the front-rear direction. Then, one of the plurality of protrusions 10 is arranged between the supply port 5A of the cooling device 5 and the inner wall surface side opening of the ventilation path 8 similarly to the barrier 2C of the first embodiment. In the following description, the protrusion 10 arranged between the cooling device 5 and the inner wall surface side opening of the ventilation path 8 is also referred to as a barrier 10.

By providing the barrier 10, as in the case of providing the barrier 2C of the first embodiment, it is possible to prevent the coolant from entering the ventilation passage 8.

If a plurality of protrusions 10 are provided as described above, the space between the case 1 and the stator 2 is divided by the four protrusions 10 in the cross section shown in FIG. However, since the spaces divided in FIG. 4 communicate with each other outside both ends of the stator holder 2B in the front-rear direction, the pressure of the entire case 1 can be adjusted by one pressure adjusting device 6.

In this embodiment, the press-fitting projection 10 is formed as a part of the case 1, but a part of the outer wall surface of the stator 2 may be formed as a projection in contact with the inner wall surface of the case 1.

As described above, in the present embodiment, the barrier 10 formed as one part of the case or part of the stator 2 is provided between the supply port 5A of the cooling device 5 and the inner wall surface side opening of the ventilation path 8. Therefore, it is possible to suppress the inflow of the cooling liquid into the air passage 8 and to suppress the impregnation of the breathing film of the pressure regulator 6 with the cooling liquid.

Although the embodiment of the present invention has been described above, the above embodiment merely shows a part of the application example of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

Claims

A stator,
A case accommodating the stator,
A rotation shaft rotatably supported by the case,
A rotor fixedly supported on the rotating shaft,
A cooling device for injecting a cooling liquid toward the stator;
A ventilation path that penetrates from the inner wall surface to the outer wall surface of the case,
A pressure regulator having a breathing membrane that allows passage of air, and connected to the outer wall surface side opening of the ventilation passage,
In an electric motor unit including
An electric motor unit comprising a barrier formed as a part of the case or a part of the stator between the supply port of the cooling device and the inner wall surface side opening of the ventilation path.
The electric motor unit according to claim 1,
The electric motor unit, wherein the supply port is opened at a position serving as an upper surface when the case is in use.
The electric motor unit according to claim 1 or 2,
The barrier is a protrusion in which a part of the outer circumference of the stator projects in the radial direction of the stator, and the length from the most protruding portion to the rotation center of the rotation shaft is the rotation center of the rotation shaft of the stator. An electric motor unit that is longer than the length up to the portion that receives the cooling liquid.
The electric motor unit according to any one of claims 1 to 3,
The electric motor unit, wherein the air passage is horizontal with respect to the ground in a use state, or is inclined so that an end portion on the outer wall surface side of the case is higher than an end portion on the inner wall surface side of the case.