JP3570450B2 - Motor cooling circuit - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electric motor, and more particularly to a technique for preventing a characteristic change due to heat generation of the motor.
[0002]
[Prior art]
The rotor of the electric motor generates heat due to eddy current loss and hysteresis loss generated in a core iron core constituting the rotor. These losses increase as the load on the motor increases and the supplied current increases, and accordingly, the amount of heat generated also increases. For this purpose, U.S. Pat. No. 4,418,777 discloses that oil from an oil pump is supplied to an axial oil passage of a rotor shaft to cool the motor with oil, from which a radial oil passage of the rotor shaft is provided. A motor for driving an electric vehicle that supplies an axial oil passage that penetrates the core through a radial oil passage in the core that is formed by further laminating steel plates, and cools the rotor with oil flowing in the core. Is disclosed. In this cooling circuit, oil is supplied to the axial oil passage of the core from the radial oil passage at the axial center position, so that two oil flows in the axial oil passage are provided. And flows in opposite directions.
[0003]
[Problems to be solved by the invention]
By the way, in a cooling circuit like the above-mentioned conventional technology, initially, when a centrifugal force acts on the oil as when the vehicle turns, or when the motor is attached to the vehicle by the inclination given to the motor during traveling due to the inclination of the road or the mounting posture of the motor to the vehicle. When the rotor shaft of the motor is inclined with respect to the horizontal plane due to the inclination or the like given to the motor from above, the oil supplied from the center position to the axial oil passage of the core is biased to one side from that position. Since the flow and the flow in the opposite direction are interrupted, there is a problem that a steady flow of oil cannot be secured and the entire rotor cannot always be efficiently cooled.
[0004]
Accordingly, the present invention is that the flow of oil through the rotor so that the flow to constantly transverse to the rotor in the axial direction, while reliably cooling the whole rotor at all times, further, the coil end of the stator It is cooled reliably to protect the coil from heat, further the purpose of providing a cooling circuit of a motor which can suppress the increase in electrical resistance of the coil.
[0005]
[Means for Solving the Problems]
To achieve the above Symbol object, the present invention includes a rotor shaft, is fitted on the rotor shaft, a core formed by stacking a plurality of steel plates, the rotor comprising a radially outer of the rotor And a stator having a coil end protruding at an axial end, wherein the rotor shaft has 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 first and second first and second clamps which are fitted to the rotor shaft at both axial ends of the core of the rotor to clamp the core . A plate is provided, and the first plate is provided with a connecting oil passage that guides oil in a radial oil passage of the rotor shaft to one end of an axial oil passage of the core, on a surface on which an end surface of the core is applied. Formed on the second plate, An oil hole communicating with the other end of the axial oil passage of the core and opening radially inside the coil end of the stator is formed, and supply means for supplying oil to the axial oil passage of the rotor shaft is provided. It is characterized by the following.
[0006]
Next, as another configuration to achieve the above purposes SL, the present invention includes a rotor shaft, is fitted on the rotor shaft, a core formed by stacking a plurality of steel plates, the rotor consisting of, A stator disposed radially outward of the rotor and having first and second coil ends projecting from both ends in the axial direction, wherein the rotor shaft comprises an axial oil passage and The core has first and second radial oil passages communicating with the axial oil passage, and the core has first and second axial oil passages penetrating the core in the axial direction. First and second plates are provided at both ends of the core in the axial direction to hold the core by being fitted to the rotor shaft, and the first plate has an oil in a first radial oil passage of the rotor shaft. Connection to one end of a first axial oil passage of the core A first oil hole communicating with one end of a second axial oil passage of the core and opening radially inward of a first coil end of the stator; and a second oil plate formed in the second plate. A second connecting oil passage that guides oil in a second radial oil passage of the rotor shaft to the other end of a second axial oil passage of the core, and a second communication oil passage other than the first axial oil passage of the core. A second oil hole communicating with the end and opening radially inside the second coil end of the stator is formed, and supply means for supplying oil to an axial oil passage of the rotor shaft is provided. Features.
In this case, it is effective to adopt a configuration in which the first communication oil passage is formed on a surface of the plate that is applied to an end surface of the core.
It is also effective to adopt a configuration in which the second communication oil passage is formed on a surface of the plate that is applied to an end surface of the core.
[0007]
The rotor in each of the above configurations may be configured to have a permanent magnet.
[0008]
The supply means in each of the above configurations is specifically composed of an oil receiver and an oil supply pipe for connecting the oil receiver to an axial oil passage of the rotor shaft.
[0009]
Function and effect of the present invention
In the above configuration, the oil supplied from the axial oil passage of the rotor shaft by the supply means of the cooling circuit is supplied to the axial oil passage of the rotor shaft, the radial oil passage of the rotor shaft, and the first plate. The flow is a one-way flow from the end of the axial oil passage of the core to the other end via the communication oil passage. Therefore, even when the rotor shaft of the motor is inclined with respect to the horizontal plane or when centrifugal force acts on the oil, the flow of oil in the axial oil passage of the core does not stop, Is ensured, and the entire rotor can be reliably cooled.
[0010]
Further, the oil is supplied to the axial oil passage of the core through a first plate having a communication oil passage formed on a surface applied to an end surface of the core separate from the core. Therefore, machining of the rotor is simplified. In addition, since 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 constituting the core, the shapes of the laminated steel plates are all the same. Since the shape can be unified, the number of component types can be reduced.
[0011]
Further, the oil that has passed in one direction in the axial oil passage of the core is supplied to the coil end of the stator by the centrifugal force of the rotor from the oil hole of the second plate. Therefore, the oil supplied to the axial oil passage of the core passes through the oil passage in the axial direction, becomes a one-way flow from one end to the other end, and extends over the entire axial length of the rotor, so that the core can be cooled by heat exchange. In addition, after that, the coil is supplied to the coil end of the stator and cooled by heat exchange with the coil end, whereby the enamel, the varnish, and the insulating paper can be protected from heat and the increase in electric resistance can be suppressed.
[0012]
Next, in the configuration described in claim 2, 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 and the first oil passage of the plate. After passing through the connecting oil passage, it flows as a one-way flow through the first axial oil passage of the core, and is supplied from the second oil hole to the second coil end of the stator by centrifugal force of the rotor. On the other hand, through the second radial oil passage of the rotor shaft and the second communication oil passage of the plate, the flow flows in the second axial oil passage of the core as a one-way flow in the opposite direction. The oil is supplied to the first coil end of the stator by the centrifugal force of the rotor.
[0013]
Accordingly, the oil supplied to the first and second axial oil passages of the core becomes a one-way flow in opposite directions from one end to the other end for each of the first and second axial oil passages. The core can be cooled by heat exchange performed at a plurality of locations in the entire length in the axial direction of the rotor and also in the circumferential direction of the rotor, and further 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 electric resistance.
[0014]
Further, the supply of the oil to the first and second axial oil passages of the core is performed through separate first and second plates provided at the end of the core. Complicating the processing of the rotor due to the formation of the communication oil passage in the core itself can be avoided. In addition, since 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 constituting the core, the shapes of the laminated steel plates are all the same. Since the shape can be unified, the number of component types can be reduced.
In the configuration according to the third or fourth aspect , the connection oil passage is formed between the core of the rotor and the plate, thereby facilitating the processing of the plate.
[0015]
Further, in the configuration of the fifth aspect , the plate forming the communication oil passage can be a common part with the holding means of the plurality of laminated steel plates forming the core.
[0016]
Further, according to the configuration of the sixth aspect , the core and the permanent magnet are reliably cooled, so that heat generation due to eddy current loss and hysteresis loss of the core and irreversible demagnetization of the permanent magnet can be suppressed.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The motor according to this embodiment is a DC brushless motor. First, the schematic configuration will be described. As shown in FIG. 1, an axially expanded cross section shows a motor including a rotor case 2 rotatably supported at both ends via a bearing 11 on a motor case 10, and a motor rotating around the rotor shaft 2. A plurality of (six in the circumferential direction) permanent magnets 31 corresponding to the number of poles (6 poles in the present embodiment) are arranged at equal pitch angles, and a large number of iron cores made of electromagnetic steel sheets are laminated in the axial direction. A rotor 3 composed of a core 30 formed as described above, and a core 40 that is non-rotatably fitted to the motor case 10, is disposed radially outward of the rotor 3, and has a large number of iron cores also composed of electromagnetic steel plates laminated in the axial direction. The first and second coil ends 41a and 41b (hereinafter, each member is separated from each other as necessary in order to distinguish a positional relationship) in which a coil portion is inserted into a slot of the core 40 and protrudes from both ends in the axial direction of the core 40. And a stator 4 having a British subjecting lowercase identification code) to the end of the reference numeral numbers. In the drawing, reference numeral 6 denotes a resolver fixed to one end of the rotor shaft 2 and detecting a magnetic pole position from rotation of the rotor shaft 2.
[0018]
In the present embodiment, the motor having such a configuration is an electric vehicle drive unit in which the motor case 10 is combined with the gear case 90 and combined, and is integrated with the differential device 9. Therefore, the gear 91 fixed to one end of the rotor shaft 2 is drivingly connected to the differential case 96 via the large-diameter gear 92, the counter shaft 93, the small-diameter gear 94, and the ring gear 95. The differential device 9 is connected to the left and right axles via a universal joint.
[0019]
As shown in detail in FIG. 3, the rotor 3 is disposed at both ends in the axial direction of the core 30, positions the plurality of permanent magnets 31 in the axial direction, and sandwiches the first and second steel plates constituting the core 30. It has second plates 21a and 21b. Each of these plates has exactly the same shape. As shown in detail in FIG. 5, three grooves 24 forming a communication oil passage are formed on the side of the plate that is abutted against the end face of the core 30. I have. These grooves 24 are interconnected by a circumferential groove 24 ′ on the inner circumferential side, extend radially at equal angular (120 ° in this embodiment) intervals, and extend in an axial oil passage 32 described in detail after the rotor 3. It ends at the position corresponding to the end. The plate 21 is further provided with three oil holes 25. These are provided at an equal angle (120 ° in the present embodiment) at an intermediate portion of each groove 24 at the same diameter position as the terminal end position of each groove 24, and the plate 21 is moved in the thickness direction. Penetrates.
[0020]
Returning to FIG. 3, a cooling circuit in the motor is formed in the rotor shaft 2, and is formed in the axial oil passage 22, the first and second radial oil passages 23 a and 23 b connected thereto, and the core 30. A first and a second axial oil passages 32a and 32b penetrating in the radial direction inside the permanent magnet 31; and a first radial oil passage 23a of the rotor shaft 2 formed on the first plate 21a. The diameter of the first coil end 41a of the stator 4 is communicated with the first connecting oil passage 24a communicating with the first axial oil passage 32a of the core 30 and the second axial oil passage 32b of the core 30. A first oil hole 25a opening inward in the direction is formed in the second plate 21b, and a second axial oil passage 23b of the rotor shaft 2 is connected to a second axial oil passage 32b of the core 30. The second communication oil passage 24b and the first axial oil passage 3 a and a supply means 5 for supplying oil to the axial oil passage 22 of the rotor shaft 2 (FIG. 1). See).
[0021]
As shown in FIG. 4, in this embodiment, the axial oil passage 32 in the core 30 is formed such that an oil passage peripheral surface 32 ′ adjacent to the permanent magnet 31 is radially inward of each of the permanent magnets 31. A parallel surface having a width almost comparable is formed along the surface 31 '. The core 30 of the rotor 3 is formed by stacking, in the axial direction, iron cores made of a plurality of steel plates 30 'having the same shape.
[0022]
As shown in FIG. 1, in this embodiment, the supply means 5 of the cooling circuit includes an oil supply pipe 50 inserted at one end of the axial oil passage 22 of the rotor shaft 2 from the gear case 90 connected to the motor case 10. It is composed of As shown in FIG. 2 as viewed from the gear case 90 side, the oil supply pipe 50 includes an oil receiver 51 at one end. The oil receiver 51 is positioned so as to straddle the outer periphery of a ring gear 95 and a large-diameter gear 92 (only the outline is shown in FIG. 2) disposed in the gear case 90. It has the function of collecting the oil scooped up by the rotation 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 is a weir that keeps the oil level on the motor case 10 side at the lowermost point on the outer periphery of the rotor 3 indicated by a dotted line in the figure. Perform the function of Further, the two cases 10 and 90 are communicated with each other through an orifice 53 formed below the opening 52, and the orifice 53 functions to balance the oil levels of the two.
[0023]
In the motor cooling circuit configured as described above, the oil that serves both of lubrication and cooling is mainly contained in the gear case 90 up to the level indicated by the dotted line in the middle of FIG. When the operation of the motor is started from this state, the ring gear 95 driven by the motor rotates counterclockwise in FIG. 2 and the large-diameter gear 92 rotates clockwise in FIG. The oil is collected by the oil receiver 51. The collected oil is guided to an oil supply pipe 50 and is supplied into the axial oil passage 22 of the rotor shaft 2 from the gear case 90 side.
[0024]
In FIG. 3, the flow of oil on the motor side in the motor cooling circuit configured as described above is indicated by an arrow, and the oil supplied to the axial oil passage 22 of the rotor shaft 2 as described above. Flows along the peripheral surface of the axial oil passage 22 due to centrifugal force caused by the rotation of the rotor shaft 2, while entering the first radial oil passage 23 a and the first connecting oil passage 24 a of the plate 21 a and the core 30. Is sprayed from the second oil hole 25b of the plate 21b to one of the coil ends 41b by the centrifugal force of the rotor 3 through the first axial oil passage 32a. On the other hand, through the second radial oil passage 23b, the second communication oil passage 24b of the plate 21b, and the second axial oil passage 32b of the core 30, the rotor 3 is moved from the first oil hole 25a of the plate 21a. Is sprayed on the other coil end 41a by the centrifugal force of. 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 around the core 30 are reliably cooled by one-way flow, and the eddy current loss of the core 30 is reduced. And the irreversible demagnetization of the permanent magnet 31 is suppressed, and the oil is discharged from the first and second oil holes 25 to supply the oil to the coil ends 41 at both ends of the stator 4 so that the oil is reliably discharged. By cooling, it is possible to protect the coil enamel, varnish, and insulating paper against heat, and to suppress an increase in electric resistance.
[0025]
The oil that has cooled the motor in this way travels through the motor case 10 or drips from various parts and collects below the motor case 10, and the oil exceeding the lower surface level of the opening 52 returns to the gear case 90 side. During the operation of such a motor, oil flows through the oil passages and the like, so that the oil level in the gear case 90 decreases to the level indicated by the dotted line at the bottom in FIG. Keep the level at the upper dotted line. When the operation of the motor is stopped, both oil levels gradually balance with the flow of oil through the orifice 53, and eventually reach the level shown by the dotted line in the middle part of the figure.
[0026]
As described above in detail, in this cooling circuit, oil introduced into the axial oil passage 22 of the rotor shaft 2 is supplied to the rotor 4 in order to achieve both oil cooling of the coil on the stator 4 side and oil cooling of the core 30 on the rotor 3 side. It is guided into the core 30 from the connecting oil passage 24 of the plate 21 disposed on both sides of the rotor core 30 through the radial oil passage 23 of the shaft 2. The axial oil passages 32 in the core 30 are arranged uniformly in the circumferential direction as oil passages in which flow directions are opposite in the core 30, thereby cooling the core 30 evenly. Then, this oil comes out of the opposite plate 21 and is sprayed inside the coil end 41 by centrifugal force. As shown in FIG. 4, six oil passages in the core 30 are provided in correspondence with the number of six poles, and three of the half of them are alternately provided on one side of the plate 21 on one side. And discharges it to the other plate 21. As a result, the oil flow in each of the axial oil passages becomes a one-way flow from one end to the other end, so that the oil flow is always maintained, and finally, the oil can be surely led out to the coil ends 41 on both sides. Thus, a flow of cooling oil without branching is always formed in the cooling section. In addition, the plates 21 on both sides of the core 30 as components constituting the oil passage are made to be common as components by having exactly the same shape, and the steel plates 30 'constituting the core 30 are also unified. By all having the same shape, they are shared as parts.
[0027]
As described above, the present invention has been described in detail based on the embodiments. However, the present invention is not limited to these embodiments, and may be implemented by changing various specific configurations within the scope of the claims. Can be. In particular, the supply means can be constituted by an oil pump driven by rotation of a motor or a gear portion.
[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 in a direction transverse to the axis of a rotor core showing a positional relationship between a rotor and a 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 communication oil passage 24b 2 communication oil passage 25a first oil hole 25b second oil hole 30 core 30 'steel plate 32a first axial oil passage 32b second axial oil passage 41a first coil end 41b second coil end
50 Refueling pipe
51 Oil receiver

Claims (6)

A rotor composed of a rotor shaft and a core fitted on the rotor shaft and formed by stacking a plurality of steel plates;
A stator disposed radially outward of the rotor and having a coil end projecting at an axial end, a motor cooling circuit comprising:
The rotor shaft has an axial oil passage and a radial oil passage communicating with the axial oil passage,
The core has an axial oil passage penetrating the core in the axial direction,
First and second plates are provided at both axial ends of the core of the rotor to fit the rotor shaft and sandwich the core ,
In the first plate, a connecting oil passage that guides oil in a radial oil passage of the rotor shaft to one end of an axial oil passage of the core is formed on a surface side applied to an end surface of the core,
The second plate is formed with an oil hole that communicates with the other end of the axial oil passage of the core and that opens radially inside a coil end of the stator.
A cooling circuit for a motor, wherein a supply means for supplying oil to an axial oil passage of the rotor shaft is provided. A rotor composed of a rotor shaft and a core fitted on the rotor shaft and formed by stacking a plurality of steel plates;
A stator disposed radially outward of the rotor and having first and second coil ends projecting at both axial ends;
In the motor cooling circuit consisting of
The rotor shaft has an axial oil passage and first and second radial oil passages communicating with the axial oil passage,
The core has first and second axial oil passages penetrating the core in the axial direction,
First and second plates are provided at both axial ends of the core of the rotor to fit the rotor shaft and sandwich the core ,
The first plate has a first connecting oil passage for guiding oil in a first radial oil passage of the rotor shaft to one end of a first axial oil passage of the core, and a second connecting oil passage for the core. A first oil hole communicating with one end of the axial oil passage and opening radially inside a first coil end of the stator;
A second connecting oil passage that guides oil in a second radial oil passage of the rotor shaft to the other end of a second axial oil passage of the core; A second oil hole that communicates with the other end of the axial oil passage and that opens on the radial inside of the second coil end of the stator;
A cooling circuit for a motor, wherein a supply means for supplying oil to an axial oil passage of the rotor shaft is provided. 3. The motor cooling circuit according to claim 2 , wherein the first communication oil passage is formed on a surface of the plate that is applied to an end surface of the core. 4. The second communication oil passage is formed in said side to be placed against the end face of the core plate, according to claim 2 or 3 cooling circuit of a motor according. The motor cooling circuit according to any one of claims 1 to 4 , wherein the rotor has a permanent magnet. The motor cooling circuit according to any one of claims 1 to 5 , wherein the supply means includes an oil receiver and an oil supply pipe that connects the oil receiver to an axial oil passage of the rotor shaft.

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