JP6834640B2 - Oil channel structure of electric motor - Google Patents

Description

The present invention relates to the structure of an oil passage through which lubricating oil (oil) for cooling an electric motor or the like flows, and is configured to supply lubricating oil particularly through a rotating shaft inserted along the rotation center axis of the rotor. It relates to the structure of the oil channel that is being used.

For example, a large electric motor such as an electric motor used as a driving force source for a vehicle tends to have a high temperature due to a large amount of electric power supplied. Further, the electric motor may not be housed in the casing by itself, but may be housed in the casing together with peripheral members such as bearings and gear mechanisms. In this type of electric motor, lubricating oil is supplied not only for cooling but also for lubrication of peripheral members. Patent Document 1 describes an example of a configuration for supplying lubricating oil to an electric motor.

In the configuration described in Patent Document 1, the rotor shaft is configured as a hollow shaft, and is supported by a pair of left and right bearings at predetermined positions inside the casing. A predetermined rotating shaft is inserted inside the rotor shaft, and the rotating shaft is supported by a bearing so that it can rotate relative to the rotor shaft. A lubricating oil supply path is formed on the rotating shaft along its central axis, and a position corresponding to approximately the center of the rotor in the axial direction reaches the outer peripheral surface of the rotating shaft from the supply path. A small-diameter branch hole is formed. Of the inner peripheral portion of the rotor shaft, a portion of a predetermined range including a position facing the opening end of the branch hole in the axial direction is large so that a predetermined gap is formed between the inner peripheral portion of the rotor shaft and the outer peripheral surface of the rotating shaft. It is formed in the diameter. An oil hole (temporarily used as a cooling oil passage) is formed so as to reach the rotor from the large diameter portion. Further, a discharge hole is formed in the rotor shaft at a position off the rotor in the axial direction from the large-diameter portion to the outer peripheral surface of the rotor shaft. Then, inside the large-diameter portion, a weir is provided in the portion between the cooling oil passage and the discharge oil passage, and the amount of lubricating oil that has flowed into the inside of the large-diameter portion through the supply passage and the branch hole. When is excessive, excess lubricating oil is allowed to flow over the weir to the discharge path hole side, and the excess lubricating oil is discharged to the outside from the discharge hole.

Japanese Unexamined Patent Publication No. 2014-60857

In the configuration described in Patent Document 1, when the amount of lubricating oil supplied to the inner peripheral side of the rotor shaft is excessive, the excess lubricating oil is discharged from the discharge hole to the outer peripheral side of the rotor shaft, so that the rotor It is possible to avoid or suppress the inconvenience that the lubricating oil is excessively supplied to the bearings and gears which are peripheral members of the above, the resistance due to the viscosity of the lubricating oil increases, and the power loss increases. On the other hand, if the electric motor operates as a motor or a generator, the rotor shaft rotates together with the rotor, and centrifugal force acts on the lubricating oil of the large-diameter portion provided on the inner peripheral side of the rotor shaft. Therefore, when the rotor shaft is rotating, the lubricating oil in the large-diameter portion is positively discharged outward in the radial direction. Therefore, the lubricating oil is sucked into the large-diameter portion from the supply path, and the suction amount increases as the rotation speed of the rotor shaft increases. Since the supply path is an oil path that supplies not only the lubricating oil to the rotor but also the lubricating oil to the bearings and gears provided inside the casing together with the rotor, the rotor is passed through the large-diameter portion. In addition, if a large amount of lubricating oil flows toward the outside thereof, there is a possibility that the lubricating oil for other members such as bearings and gears will be insufficient.

The present invention has been made by paying attention to the above technical problems, and an object of the present invention is to provide an oil passage structure for an electric motor capable of supplying lubricating oil to a rotor and its peripheral members in just proportion. Is.

In order to achieve the above object, in the present invention, the rotor shaft is rotatably arranged on the same axis as the rotation shaft on the outer peripheral side of the rotation shaft, and inside the rotation shaft in the axial direction of the rotation shaft. A supply path for lubricating oil is formed along the same, and a branch hole that opens from the supply path to the outer peripheral surface of the rotary shaft is formed on the rotary shaft, and the branch hole flows out from the branch hole to the outer peripheral side of the rotary shaft. A cooling oil passage for supplying lubricating oil to the rotor core provided integrally with the rotor shaft on the outer peripheral side of the rotor shaft opens on the inner peripheral surface of the rotor shaft and is formed in the radial direction of the rotor shaft. in the oil passage structure of the electric motor is, space is provided in a range where constant between the outer peripheral surface of the rotary shaft and the inner peripheral surface of the rotor shaft, the cooling oil passage is open to said cavity has a first opening, atmospheric pressure introducing portion provided for communicating the front Symbol cavity at a predetermined position of the atmospheric pressure, the atmospheric pressure introducing portion has a second opening you open to said cavity A step is provided on the inner peripheral surface between the first opening and the second opening, and the radial position of the second opening from the axis is the radial position of the first opening from the axis. It is characterized in that it is set on the inner peripheral side.

In the present invention, the supply path provided on the rotating shaft and the cooling oil path for supplying the lubricating oil to the rotor core are communicated with each other through a vacant space. When the rotor shaft rotates, the lubricating oil inside the vacant space is sent to the rotor core side by centrifugal force, and therefore the suction force due to the centrifugal force acts on the lubricating oil in the vacant space. Atmospheric pressure introduction is open in the vacant space, but since the cooling oil passage is open to the vacant space on the outer peripheral side of the opening of the atmospheric pressure introduction part, the lubricating oil in the vacant space is The amount of lubricating oil that is guided toward the opening of the cooling oil passage and discharged from the atmospheric pressure introduction part to the atmospheric pressure part is small or zero, and the atmospheric pressure introduction part is blocked by the lubricating oil. Is avoided or suppressed. Then, the vacant space communicates with the atmospheric pressure part through the atmospheric pressure introduction part, and the vacant space does not have a negative pressure lower than the atmospheric pressure, and as a result, the lubricating oil positively enters the vacant space from the supply oil passage. It is possible to avoid or suppress the suction of the lubricating oil and the decrease in the amount of lubricating oil flowing from the supply oil passage to a place other than the empty space. After all, according to the present invention, the supply of the lubricating oil to the rotor core and the supply of the lubricating oil to the parts other than the rotor are performed without being particularly affected by the centrifugal oil pressure due to the rotation of the rotor core and the rotor shaft. Lubricating oil can be supplied in just proportion to each of the parts other than the rotor.

It is sectional drawing which shows one Embodiment of this invention typically. It is a partial view which takes out a part of it and describes it. It is a graph which shows the result of having measured the amount of lubricating oil flowing through each branch hole. It is sectional drawing which shows the other embodiment of this invention schematically.

Embodiments of the present invention are schematically shown in FIG. The example shown here is an example in which lubricating oil is supplied to an electric motor (motor generator) 1 that functions as a driving force source for a vehicle, and a rotor core 3 is provided on the outer peripheral side of a rotor shaft 2 that is a hollow shaft. It is provided integrally. The rotor shaft 2 is rotatably supported by a bearing 4. Further, a rotating shaft 5 is inserted inside the rotor shaft 2, and the rotating shaft 5 and the rotor shaft 2 are arranged on the same axis C and are configured to be relatively rotatable.

A supply oil passage 6 for supplying lubricating oil is formed along the axis C passing through the center of the rotating shaft 5. The supply oil passage 6 is communicated with an oil pump (not shown), and the lubricating oil discharged by the oil pump is circulated to supply the lubricating oil to the rotor core 3, and other than the rotor core 3 such as the bearing 4 or another bearing 7. It is configured to supply lubricating oil to other members. In order to supply the lubricating oil in this way, a plurality of branch holes 8a, 8b, 8c extending from the supply oil passage 6 to the outer peripheral surface of the rotary shaft 5 are formed in the rotary shaft 5 in the radial direction thereof. ..

In the example shown in FIG. 1, a space 9 is formed between the inner peripheral surface of the rotor shaft 2 and the outer peripheral surface of the rotating shaft 5. This vacant space 9 is a space portion created between the two by making the inner diameter of the rotor shaft 2 larger than the outer diameter of the rotating shaft 5, and the rotor shaft 2 and the rotating shaft are formed at both ends of the rotor shaft 2 in the axial direction. By interposing a sealing material (or bearing) 10 between it and 5, it is sealed in the axial direction. Of the branch holes 8a, 8b, 8c, the branch holes 8a, 8c on both sides in the axial direction are provided at a location outside the vacant space 9, that is, a location outside the rotor shaft 2 in the axial direction. The branch hole 8b at the center in the axial direction is formed so as to open inside the vacant space 9. Further, the inner diameter of the vacant space 9 is larger at the central portion in the axial direction than at both end portions. Hereinafter, a portion of the vacant space 9 having a large inner diameter is referred to as a large diameter portion 9A, and a portion having an inner diameter on both ends in the axial direction smaller than that of the large diameter portion 9A is referred to as a small diameter portion 9B. The boundary between the large diameter portion 9A and the small diameter portion 9B has a tapered shape (inclined surface) in which the inner diameter gradually changes.

A cooling oil passage 11 for supplying the lubricating oil in the vacant space 9 to the rotor core 3 for cooling is provided. In the example shown in FIG. 1, the cooling oil passage 11 is formed so as to penetrate substantially the central portion of the rotor shaft 2 and the rotor core 3 in the axial direction in the radial direction. Therefore, the opening 11A on the vacant space 9 side of the cooling oil passage 11 is located in the large diameter portion 9A. In other words, the predetermined range including the opening 11A of the cooling oil passage 11 is the large diameter portion 9A or the vacant space 9.

Further, the rotor shaft 2 is formed with an atmospheric pressure introduction hole 12 corresponding to the atmospheric pressure introduction portion in the embodiment of the present invention in which the vacant space 9 communicates with the atmospheric pressure portion. The atmospheric pressure portion is, for example, a portion on the outer peripheral side of the rotor shaft 2 that is off the rotor core 3 in the axial direction, or a space portion inside a casing (not shown) that houses the electric motor 1. .. Therefore, the atmospheric pressure introduction hole 12 in the example shown in FIG. 1 is formed so as to penetrate one end side of the rotor shaft 2 in the radial direction. The opening 12A on the vacant space 9 side is located in one of the small diameter portions 9B.

Here, the relative positions of these openings 11A and 12A will be described. As shown in FIG. 2, the opening 11A of the cooling oil passage 11 is open to the large diameter portion 9A. On the other hand, since the opening 12A of the atmospheric pressure introduction hole 12 is open to the small diameter portion 9B, the radial position (distance) R _{11 of} the former opening 11A from the axis C is the latter opening 12A. It is larger than the radial position (distance) R _{12 from the axis C.} In other words, the opening 11A of the cooling oil passage 11 is located on the side having the larger inner diameter and the opening 12A of the atmospheric pressure introduction hole 12 has the inner diameter with the step portion T between the large diameter portion 9A and the small diameter portion 9B sandwiched. It is located on the small side of.

In the oil passage structure described above, the lubricating oil is pressurized by an oil pump (not shown) and sent to the supply oil passage 6, and flows inside the oil passage structure, for example, from the branch holes 8a, 8b, 8c described above to the rotor core 3 and the bearing 4. It flows out toward. When the rotating shaft 5 and the rotor shaft 2 are rotating, the lubricating oil that has flowed out from the branch hole 8b to the vacant space 9 receives centrifugal force along with the shafts 5 and 2 and is pushed outward in the radial direction. .. That is, it receives centrifugal pressure. The lubricating oil that has received the centrifugal hydraulic pressure is pressed against the inner peripheral surface of the rotor shaft 2 (the outer surface in the radial direction of the void 9). In that case, since the inner diameter of the vacant space 9 is larger in the large diameter portion 9A, the lubricating oil in the small diameter portion 9B flows toward the large diameter portion 9A side by centrifugal oil pressure.

The lubricating oil collected on the large diameter portion 9A side flows to the outer peripheral side of the rotor core 3 through the cooling oil passage 11, and in the process, the heat of the rotor core 3 is taken away, and the rotor core 3 is cooled by the lubricating oil. .. Further, since the lubricating oil of the small diameter portion 9B flows to the large diameter portion 9A side as described above, the amount of the lubricating oil discharged to the outside from the atmospheric pressure introduction hole 12 is small or almost none. Further, it is avoided or suppressed that the opening 12A of the atmospheric pressure introduction hole 12 is blocked by the lubricating oil. Rather, since the lubricating oil actively flows out from the large diameter portion 9A through the cooling oil passage 11 toward the outer peripheral side of the rotor core 3, the atmospheric pressure introduction hole 12 due to the suction action accompanying such outflow of the lubricating oil. The outside air is sucked from. Therefore, the pressure inside the vacant space 9 is maintained at substantially atmospheric pressure. Therefore, even if the lubricating oil is positively discharged from the vacant space 9 by centrifugal oil pressure, the action of sucking the lubricating oil of the supply oil passage 6 into the vacant space 9 through the branch hole 8b does not occur, or such an action does not occur. Will be extremely small. Therefore, it is possible to avoid or suppress a situation in which the amount of lubricating oil supplied from the supply oil passage 6 to a location or member other than the rotor core 3 via other branch holes 8a, 8c and the like is reduced or insufficient.

Here, the change in the amount of lubricating oil passing through the branch holes 8a, 8b, 8c depending on the presence or absence of the atmospheric pressure introduction hole 12 is shown. FIG. 3 shows the flow rates of the lubricating oils of the branch holes 8a, 8b, and 8c when the atmospheric pressure introduction holes 12 are provided ((a) in FIG. 3) and the branch holes when the atmospheric pressure introduction holes 12 are not provided. The results of measuring the flow rates of the lubricating oils of 8a, 8b, and 8c ((b) in FIG. 3) are shown. When the atmospheric pressure introduction hole 12 is provided, as shown in FIG. 3A, the amount of lubricating oil flowing through the branch hole 8b opened in the vacant space 9 is the largest, and the amount of lubricating oil flows on the upstream side in the flow direction of the lubricating oil. The amount of lubricating oil flowing through the branch hole 8a is the smallest, and the amount of lubricating oil flowing through the branch hole 8c on the downstream side is medium. On the other hand, when the atmospheric pressure introduction hole 12 is not provided, as shown in FIG. 3B, the amount of lubricating oil flowing through the branch hole 8b opened in the vacant space 9 is the atmospheric pressure. This is significantly increased as compared with the case where the introduction hole 12 is provided, whereas the amount of lubricating oil flowing through the branch holes 8a and 8c on the upstream side and the downstream side is reduced. As is known from these measurement results, by maintaining the pressure of the vacant space 9 at or near the atmospheric pressure, the suction of the lubricating oil by the vacant space 9 is prevented or suppressed, and as a result, the pressure of the atmospheric pressure is directly increased. It is possible to avoid or suppress a decrease in the amount of lubricating oil distributed to the branch holes 8a and 8c that are open at the location or the location communicating with the location, and the supply of lubricating oil to the rotor core 3 and other locations is excessive. It can be done without any shortage.

The atmospheric pressure introduction portion in the present invention does not have to be the atmospheric pressure introduction hole 12 formed by penetrating the rotor shaft 2 in the radial direction as shown in FIG. 1, and the point is that the atmospheric pressure introduction portion is for a vacant space in the cooling oil passage. Any communication portion may be used as long as it is a communication portion that opens in an empty space inside the opening in the radial direction. For example, as shown in FIG. 4, a sealing material 10 is not provided on one end side of the rotor shaft 2 in the axial direction, and between the inner peripheral surface of the end side and the outer peripheral surface of the rotating shaft 5. A gap 13 may be opened, and the portion of the gap may be used as the atmospheric pressure introduction portion.

1 ... Electric motor, 2 ... Rotor shaft, 3 ... Rotor core, 4 ... Bearing, 5 ... Rotating shaft, 6 ... Supply oil passage, 7 ... Bearing, 8a, 8b, 8c ... Branch hole, 9 ... Vacancy, 9A ... Large diameter Part, 9B ... Small diameter part, 10 ... Sealing material (or bearing), 11 ... Cooling oil passage, 11A ... Opening, 12 ... Atmospheric pressure introduction hole, 12A ... Opening, 13 ... Gap, C ... Axis line, R ₁₁ ... Radial position, R ₁₂ ... Radial position, T ... Step.

Claims (1)

A rotor shaft is rotatably arranged on the outer peripheral side of the rotating shaft on the same axis as the rotating shaft, and a lubricating oil supply path is formed inside the rotating shaft along the axial direction of the rotating shaft. A branch hole is formed in the rotary shaft from the supply path to the outer peripheral surface of the rotary shaft, and the lubricating oil flowing out from the branch hole to the outer peripheral side of the rotary shaft is applied to the outer peripheral side of the rotor shaft. In the oil passage structure of the electric motor, in which the cooling oil passage provided integrally with the rotor core is opened on the inner peripheral surface of the rotor shaft and is formed in the radial direction of the rotor shaft.
Cavity is provided in a range where constant between the inner peripheral surface and the outer peripheral surface of the rotary shaft of the rotor shaft,
The cooling oil passage has a first opening that opens into the vacant space.
An atmospheric pressure introduction section is provided to communicate the vacant space with a predetermined location of the atmospheric pressure.
Wherein the atmospheric pressure introducing portion has a second opening you open to said cavity,
A step is provided on the inner peripheral surface between the first opening and the second opening.
An oil passage structure of the motor, characterized in that the radial position is set on the inner circumferential side of the radial position from the axis of the first opening from the axis of the front Stories second opening.

Images