JPH09182375A - Cooling circuit of motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent heat generation due to the generation of an eddy-current loss and a hysteresis loss by cooling the core of a rotor in a motor. SOLUTION: This motor is composed of a rotor shaft 2, a rotor 3 comprising a core 30 and a stator 4. This cooling circuit comprises an axial oil path 32 passing through the core 30 in the axial direction, an oil path inside the rotor shaft 2 for supplying oil to the oil path from the end part and a supply means 5. The oil supplied from the supply means 5 is supplied to the core 30 from the oil path 22 of the rotor shaft 2 by centrifugal force and made to flow from one end of the axial oil path 32 to the other end in one way without being retarded to cool the core and after that, is supplied to coil ends 41a, 41b to cool the stator 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor, and more particularly to a technique for preventing characteristic changes due to heat generation of the motor.

[0002]

2. Description of the Related Art A rotor of an electric motor generates heat due to an eddy current loss and a hysteresis loss generated in a core core of the electric motor. Such a loss increases as the load of the motor increases and the supplied current increases, and the amount of heat generation increases accordingly. Therefore, US Pat.
No. 18,777, in order to cool the motor with oil,
The oil from the oil pump is supplied to the axial oil passage of the rotor shaft, and from there, through the radial oil passage of the rotor shaft,
A cooling circuit for an electric vehicle drive motor that supplies oil to an axial oil passage that passes through the core through a radial oil passage in the core that is formed by stacking steel plates, and cools the rotor with the oil that flows in the core. Is disclosed. In this cooling circuit, the oil is supplied to the axial oil passage from the radial oil passage at the axially central position, so that there are two oil flows in the axial oil passage. It is divided into two and flows in opposite directions.

[0003]

By the way, in the cooling circuit as in the above-mentioned prior art, when a centrifugal force acts on the oil as when the vehicle turns, or when the road is tilted and the motor is tilted, If the rotor shaft of the motor is tilted with respect to the horizontal plane due to the inclination given to the motor from the beginning due to the mounting posture of the motor in the vehicle, the oil supplied from the central position to the axial oil passage of the core However, there is a problem in that a steady flow of oil cannot be secured and the entire rotor cannot always be cooled efficiently because the flow from one of the positions is biased toward one side and the flow in the opposite direction is stagnant.

In view of this, the present invention provides a cooling circuit for a motor that can always reliably cool the entire rotor by allowing the oil flow through the rotor to constantly flow across the rotor in the axial direction. The first purpose is to provide.

Further, according to the present invention, while maintaining the above-mentioned oil flow to surely cool the rotor, the coil end of the stator is also surely cooled to protect the coil from heat. A second object is to provide a motor cooling circuit capable of suppressing an increase in the electric resistance of the coil.

[0006]

In order to achieve the above first object, the present invention comprises a rotor shaft and a core fitted on the rotor shaft and formed by laminating a plurality of steel plates. And a stator arranged radially outside the rotor, the cooling circuit of the motor comprising:
The rotor shaft has an axial oil passage and a radial oil passage communicating with the axial oil passage, and the core has an axial oil passage that penetrates the core in the axial direction. A plate having a communication oil passage that connects the radial oil passage of the rotor shaft and one end of the axial oil passage of the core is disposed at the end of the rotor shaft, and oil is supplied to the axial oil passage of the rotor shaft. A supply means for supplying is provided.

In order to achieve the above second object, the present invention provides a rotor comprising a rotor shaft and a core which is fitted on the rotor shaft and is formed by laminating a plurality of steel plates. A stator arranged radially outward of the rotor and having first and second coil ends projecting at both ends in the axial direction, and a rotor cooling shaft comprising: The rotor having first and second radial oil passages communicating with the axial oil passage, the core having first and second axial oil passages penetrating the core in the axial direction; First and second plates, which are fitted to the shaft and arranged at both axial ends of the core of the rotor, are provided, and the first plate includes a first radial oil passage of the rotor shaft. A first connecting oil passage communicating with the first axial oil passage of the core A first oil hole communicating with the second axial oil passage of the core and opening radially inward of the first coil end of the stator is formed, and the rotor shaft is formed on the second plate. Second radial oil passage and a second axial oil passage of the core, and a second connecting oil passage of the core, and a first axial oil passage of the core, and a second of the stator. A second oil hole that is open radially inward of the coil end is formed, and a supply unit that supplies oil to the axial oil passage of the rotor shaft is provided.

[0008]

According to the structure of the first aspect,
The oil supplied from the axial oil passage of the rotor shaft by the supply means of the cooling circuit passes through the axial oil passage of the rotor shaft, the radial oil passage of the rotor shaft, the connecting oil passage of the plate, and then the axial oil passage of the core. One-way flow from the end to the other end. Therefore, even when the rotor shaft of the motor is tilted with respect to the horizontal plane or when centrifugal force acts on the oil, the oil flow in the axial oil passage of the core does not become stagnant and A flow of oil is ensured across the shaft in the axial direction, so that the entire rotor can be reliably cooled. Further, since the oil is supplied to the axial oil passage of the core via a separate plate arranged at the end of the core, the machining of the rotor is simplified.
Further, as a result, it is not necessary to form a connecting oil passage for guiding oil from the rotor shaft to the axial oil passage in a part of the plurality of laminated steel plates forming the core. Since the shapes can be unified, the number of component types can be reduced.

Next, in the structure according to the second aspect, the oil supplied from the supply means of the cooling circuit to the axial oil passage of the rotor shaft is, on the other hand, the first radial oil passage of the rotor shaft,
It flows in a one-way flow through the first axial oil passage of the core through the first connecting oil passage of the plate, and is supplied from the second oil hole to the second coil end of the stator by the centrifugal force of the rotor. It On the other hand, the second axial oil passage of the core flows through the second radial oil passage of the rotor shaft and the second connecting oil passage of the plate to form a reverse one-way flow,
Is supplied to the first coil end of the stator by the centrifugal force of the rotor. Therefore, the oil supplied to the first and second axial oil passages of the core becomes a one-way flow in mutually opposite directions reaching from one end to the other end of each of the first and second axial oil passages. It is possible to cool the core by heat exchange that is performed at a plurality of positions in the entire axial direction of the rotor and also in the circumferential direction of the rotor, and is then supplied to the first and second coil ends of the stator, By cooling the coil by heat exchange with the coil end, it is possible to protect the enamel, varnish, and insulating paper against heat, and suppress an increase in electrical resistance. Furthermore, the first of the core
Since the oil is supplied to the first and second axial oil passages through separate first and second plates arranged at the end of the core, the oil passage connecting to the core itself is formed. It is possible to avoid complication of the processing of the rotor due to the formation of the. Further, as a result, it is not necessary to form a connecting oil passage for guiding oil from the rotor shaft to the axial oil passage in a part of the plurality of laminated steel plates forming the core. Since the shapes can be unified, the number of component types can be reduced.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. The motor according to this mode is a DC brushless motor. First, a schematic configuration will be described. As shown in the axially developed cross section of FIG. 1, the motor includes a rotor shaft 2 rotatably supported at both ends by a motor case 10 via bearings 11, and a rotor shaft 2.
The rotation stopper is fitted on the upper side, and the number of poles (6 in this embodiment)
A plurality of (six in the circumferential direction) permanent magnets 31 corresponding to the poles are arranged at equal pitch angles, and a rotor 3 including a core 30 in which a large number of iron cores made of electromagnetic steel plates are laminated in the axial direction, and a motor case 10. A core 40, which is fitted around the outer periphery to prevent rotation, is arranged radially outward of the rotor 3, and has a large number of iron cores made of electromagnetic steel sheets laminated in the axial direction, and a coil portion is inserted into a slot of the core 40. Of the first and second coil ends 41a, 41b protruding from both axial ends (hereinafter, in order to distinguish the positional relationship, reference numerals of the respective members are appended with identification letters in lowercase letters at the end if necessary. 4) having a stator. In the figure, reference numeral 6 is fixed to one end of the rotor shaft 2 and
3 shows a resolver that detects the magnetic pole position from the rotation of.

In the present embodiment, the motor having such a structure is an electric vehicle drive unit in which the motor case 10 is combined with the gear case 90 to be combined with the differential unit 9. Therefore, the rotor shaft 2
A gear 91 fixed to one end of the gear is drivingly connected to a differential case 96 via a large diameter gear 92, a counter shaft 93, a small diameter gear 94 and a ring gear 95. The differential device 9
Are connected to the left and right axles via universal joints.

As shown in detail in FIG. 3, the rotor 3 is arranged at both ends of the core 30 in the axial direction and has a plurality of permanent magnets 3.
The first and second plates 21a, 21 for axially positioning 1 and sandwiching the steel plates forming the core 30.
b. Both of these plates have the exact same shape and, as shown in detail in FIG.
Is formed with three grooves 24 forming a communication oil passage on the surface side which is abutted against the end surface of the. These grooves 24 are connected to each other by a circumferential groove 24 'on the inner peripheral side and extend in the radial direction at equal angular intervals (120 ° in the present embodiment), and the axial oil passage 32, which will be described in detail after the rotor 3, is formed. It ends at the position corresponding to the end. The plate 21 is further provided with three oil holes 25. These are provided at the same diameter position as the end position of each groove 24 and at an equal angle (120 ° in the present embodiment) at the intermediate portion of each groove 24, and the plate 21 in the plate thickness direction. Penetrates.

Returning to FIG. 3, the cooling circuit in the motor is formed in the rotor shaft 2 and has the axial oil passage 22 and the first and second radial oil passages 23a and 23b communicating with the axial oil passage 22.
And the first and second axial oil passages 32a, 32 formed in the core 30 and axially penetrating the radially inner side of the permanent magnet 31.
b, a first connecting oil passage 24a formed in the first plate 21a and connecting the first radial oil passage 23a of the rotor shaft 2 and the first axial oil passage 32a of the core 30, and a core The first oil hole 25a, which is communicated with the second axial oil passage 32b of the rotor 30, and opens radially inward of the first coil end 41a of the stator 4, and the second plate 21b. The second connecting oil passage 24b that connects the second axial oil passage 23b of the second core and the second axial oil passage 32b of the core 30 is connected to the first connecting oil passage 32a. It is composed of a second oil hole 25b that opens radially inward of the second coil end 41b, and a supply means 5 (see FIG. 1) that supplies oil to the axial oil passage 22 of the rotor shaft 2. .

As shown in FIG. 4, the axial oil passage 32 in the core 30 has, in this embodiment, an oil passage circumferential surface 32 ′ adjacent to the permanent magnet 31, which is radially inward of each permanent magnet 31. Along the outer surface 31 ′ of 31 is formed a parallel surface having a substantially equal width. Then, the core 30 of the rotor 3 is
An iron core made of a plurality of steel plates 30 'having the same shape is laminated in the axial direction.

As shown in FIG. 1, the supply means 5 of the cooling circuit
In this embodiment, the oil supply pipe 50 is inserted into one end of the axial oil passage 22 of the rotor shaft 2 from the gear case 90 side connected to the motor case 10. As shown in FIG. 2 when the configuration is viewed from the gear case 90 side, the oil supply pipe 50 has an oil receiver 5 at one end thereof.
1 is provided. The oil receiver 51 is a gear case 9
Ring gear 95 and large diameter gear 92 (see FIG. 2).
Then, it is positioned so as to straddle the outer peripheral portion of (only its contour is shown), and fulfills the function of collecting the oil scraped up by the rotation of the ring gear 95 and the large diameter gear 92 at the level of the rotor shaft 2. The motor case 10 and the gear case 90 communicate with each other through an opening 52, and the lower surface of the opening 52 serves as a weir for keeping the oil level on the motor case 10 side at the lowermost outer periphery of the rotor 3 shown by the dotted line in the figure. Fulfill the function of. Further, the cases 10 and 90 are communicated with each other through an orifice 53 formed below the opening 52, and the orifice 53 has a function of balancing the oil levels of both cases.

In the cooling circuit of the motor constructed as described above, the oil that serves both as the lubrication and the cooling is mainly put in the gear case 90 to the level shown by the middle dotted line in FIG. When the operation of the motor is started from this state, the ring gear 95 driven thereby rotates counterclockwise in FIG. 2 and the large diameter gear 92 rotates clockwise,
The oil scraped up by them is collected by the oil receiver 51. The collected oil is guided to the oil supply pipe 50 and supplied from the gear case 90 side into the axial oil passage 22 of the rotor shaft 2.

In FIG. 3, the flow of oil on the motor side in the cooling circuit of the motor configured as described above is indicated by arrows, and is supplied to the axial oil passage 22 of the rotor shaft 2 as described above. The separated oil flows along the circumferential surface of the axial oil passage 22 due to the centrifugal force generated by the rotation of the rotor shaft 2, while it enters the first radial oil passage 23a and the first oil of the plate 21a.
Connecting oil passage 24a, the first axial oil passage 32a of the core 30
Through the second oil hole 25b of the plate 21b, the one coil end 41b is sprayed by the centrifugal force of the rotor 3. On the other hand, the second oil passage 23b, the second connecting oil passage 24b of the plate 21b, and the second axial oil passage 32b of the core 30 are passed through the first oil hole 2 of the plate 21a.
5a to the other coil end 4 due to the centrifugal force of the rotor 3.
It is sprayed on 1a. Therefore, when the oil flows through the first and second axial oil passages 32 of the core 30, the core 30 and the permanent magnets 31 on the outer periphery thereof are surely cooled by the one-way flow to reliably prevent the eddy current loss of the core 30. And heat generation due to hysteresis loss and irreversible demagnetization of the permanent magnet 31 are suppressed, and oil is supplied from the first and second oil holes 25 to the coil ends 41 at both ends of the stator 4 to ensure them. It can be cooled to protect the coil enamel, varnish, and insulating paper against heat, and suppress an increase in electrical resistance.

The oil after cooling the motor in this way is transmitted through the motor case 10 or dropped from each part,
Collected under the motor case 10, the portion exceeding the lower surface level of the opening 52 returns to the gear case 90 side. During the operation of such a motor, oil is flowing through the above oil passages, etc.
The oil level in the gear case 90 drops to the level of the lowermost dotted line in FIG. 2, and the oil level in the motor case 10 maintains the level of the uppermost dotted line. When the operation of the motor is stopped, the oil flow through the orifice 53 gradually balances both oil levels, and eventually reaches the level shown by the dotted line in the middle of the figure.

As described above in detail, in this cooling circuit, the oil introduced into the axial oil passage 22 of the rotor shaft 2 is used in order to achieve both the oil cooling of the coil on the stator 4 side and the core 30 on the rotor 3 side. Are guided into the core 30 through the radial oil passages 23 of the rotor shaft 2 and the connecting oil passages 24 of the plates 21 arranged on both side surfaces of the rotor core 30. The axial oil passages 32 in the core 30 are evenly arranged in the circumferential direction in the core 30 as oil passages having opposite flow directions, thereby cooling the core 30 evenly. And
This oil comes out of the plate 21 on the opposite side and is sprayed inside the coil end 41 by centrifugal force. As shown in FIG. 4, the number of axial oil passages in these cores 30 is six, which corresponds to the number of six poles, and half of them, three each, are alternately arranged on one side of the plate 21. The oil is supplied from and discharged to the other plate 21. As a result, the oil flow in each axial oil passage becomes a unidirectional flow from one end to the other end, and the oil flow is always ensured, and finally the oil can be reliably led to the coil ends 41 on both sides. As a result, a flow of cooling oil without branching is always formed in the cooling section. In addition, the plates 21 on both side surfaces of the core 30 as a component of the oil passage are made to have the same shape to be commonly used as a component.
Each of the steel plates 30 ′ constituting 0 is also unified as a part by having a unified and identical shape.

The present invention has been described above in detail based on the embodiments. However, the present invention is not limited to these embodiments, and various specific configurations may be changed within the scope of the matters described in the claims. It can be carried out. In particular, the supply means can be constituted by an oil pump driven by rotation of a motor or a gear part.

[Brief description of the drawings]

FIG. 1 is an axial sectional view of a motor according to an embodiment of the present invention.

FIG. 2 is a view in the direction of arrows AA in FIG. 1;

FIG. 3 is an axial cross-sectional view showing an oil passage arrangement by taking out a stator and a rotor of the motor.

FIG. 4 is a cross-sectional view of the rotor core in the axial cross direction showing the positional relationship between the rotor and the plate of the motor.

FIG. 5 is a perspective view showing details of the plate.

[Explanation of symbols]

 2 rotor shaft 3 rotor 4 stator 5 supply means 21a first plate 21b second plate 22 axial oil passage 23a first radial oil passage 23b second radial oil passage 24a first connecting oil passage 24b second 2 connecting oil passage 25a 1st oil hole 25b 2nd oil hole 30 core 30 'steel plate 32a 1st axial oil passage 32b 2nd axial oil passage 41a 1st coil end 41b 2nd coil end

Claims (2)

[Claims] 1. A rotor shaft, and a core fitted on the rotor shaft and formed by laminating a plurality of steel plates,
In a cooling circuit for a motor, which comprises a rotor composed of a rotor and a stator arranged radially outward of the rotor, the rotor shaft comprises an axial oil passage and a radial oil passage communicating with the axial oil passage. The core has an axial oil passage that penetrates the core in the axial direction, and a radial oil passage of the rotor shaft and an axial oil passage of the core are provided at an end portion of the core of the rotor. A cooling circuit for a motor, wherein a plate having a communication oil passage communicating with one end of the motor is provided, and a supply means for supplying oil to the axial oil passage of the rotor shaft is provided. 2. A rotor shaft, and a core fitted on the rotor shaft and formed by laminating a plurality of steel plates,
And a stator having first and second coil ends that are arranged radially outward of the rotor and that project at both ends in the axial direction. Directional oil passages and first and second radial oil passages communicating with the axial oil passages, and the core has first and second axial oil passages that penetrate the cores in the axial direction. Then, there are provided first and second plates fitted to the rotor shaft and arranged at both axial ends of the rotor core. The first plate has a first diameter of the rotor shaft. Diameter of the first coil end of the stator, which is in communication with the first connecting oil passage that connects the directional oil passage with the first axial oil passage of the core and the second connecting oil passage of the core. A first oil hole that opens on the inner side in the direction is formed, and the second plate has: The second connecting oil passage that connects the second radial oil passage of the rotor shaft and the second axial oil passage of the core, and the first axial oil passage of the core that communicates with each other. A second oil hole that is opened radially inward of the second coil end of the motor, and a supply means for supplying oil to the axial oil passage of the rotor shaft is provided. .