JP5549349B2 - Lubrication structure of electric motor - Google Patents

Description

  The present invention relates to a lubrication structure for an electric motor, and more particularly to a lubrication structure related to lubrication of a rolling bearing in an electric motor having a rolling bearing in a form used by enclosing a grease composition.

  Conventionally, electric motors having a basic structure shown schematically in FIG. 10 are used in various rotating devices. In the electric motor shown in FIG. 10, rolling bearings 10 and 20 are disposed between a housing (housing) 4 and the main shaft 1, and a stator (stator) 3 is disposed on the inner inner periphery of the housing 4. A rotor (rotor) 2 is attached to the main shaft 1. The side end of the housing 4 on the bearing 20 side is closed by a lid (cover) 5, and the main shaft 1 extends from the side end opening of the housing 4 on the opposite bearing 10 side. .

  The bearings 10 and 20 are rolling bearings, and are deep groove ball bearings in the example shown in FIG. 10 (Patent Document 1). Deep groove ball bearings can be used with a preload to improve axial rigidity and radial rigidity, are suitable for high-speed rotation, and are inexpensive and widely used in electric motors. ing. Here, although the preload structure is not shown, various structures exist.

  An example of a rolling bearing widely used in electric motors as the bearings 10 and 20 is shown in FIG. The rolling bearing 10 or the rolling bearing 20 shown in FIG. 11 is fixed to the main shaft of the electric motor as an outer ring (stationary ring) 11 mainly used as a stationary ring and fixed to the electric motor housing. An inner ring (rotating wheel) 12 used, a plurality of balls 13 that are rolling elements that rotatably support the outer ring 11 and the inner ring 12, and a cage 14 that holds the balls 13 that are the rolling elements apart from each other. And sealing devices 15 and 16 for closing end openings formed by the outer ring 11 and the inner ring 12. The sealing devices 15 and 16 in this example are shield plates formed from a metal plate. In addition, a grease composition is enclosed in a bearing internal space formed by the outer ring 11, the inner ring 12, and the sealing devices 15 and 16 for lubricating the rolling bearings 10 and 20. As a method for lubricating a rolling bearing, there is a method of circulating a lubricating oil or supplying it to an oil mist bearing in addition to a method of lubricating a grease composition, and a circulating device or an oil mist generating device. However, since it is necessary separately from the electric motor and is costly, a method of enclosing and lubricating the grease composition is widely used.

  In such an electric motor, the life of the rolling bearing often becomes the cause of determining the life of the entire motor, and therefore, research on improving the life of the rolling bearing has been conducted earnestly. Furthermore, when the load condition applied to the rolling bearing is not strict like an electric motor, the life of the rolling bearing is likely to be affected by the quality of the lubrication. Therefore, lubrication of the rolling bearing, grease to be enclosed in the rolling bearing Research on improvement is also conducted day and night.

JP 09-021424 A

  However, the performance required for electric motors is becoming stricter every day. Specifically, a material that can be used at a higher temperature and can withstand high-speed rotation is required. Not only that, in order to reduce energy loss and contribute to the global environment, even lower torque rotation performance is required. Such a requirement is particularly severe in an electric motor used for driving an electric vehicle and a hybrid vehicle that are now widely used.

  In order to solve the above problems, the present inventor has invented a lubricating structure for an electric motor having the following configuration as a result of intensive studies.

That is, a housing, a main shaft, wherein the plurality is spaced axially to hold rotatably the spindle to the laying by the housing between the housing and the main shaft rolling a bearing, a rotor disposed in the main shaft, the electric motor and a said arranged in a housing the stator,
The rolling bearing includes a stationary ring fixed to the housing, a rotating ring that is fixed to the main shaft, and a plurality of rolling elements rotatably supporting said stationary ring and the rotating ring and said rotating ring are those comprising said a sealing device disposed in the open mouth of the both end portions which are formed in the stationary ring, the grease composition is enclosed in the internal space of the rolling bearing which is defined by the sealing device,
Of the sealing devices, the sealing device disposed inside the rolling elements is a non-contact seal,
Inside the casing, lubricating oil to the position of the inner and vertically lower than the rolling bearing is characterized in that it is sealed.

  According to the said structure, lubricating oil is enclosed with the inside of a housing | casing. When the electric motor is energized and rotated, the lubricating oil enclosed in the housing becomes fine particles (mist), vaporizes, or jumps due to temperature rise, air flow, vibration, etc. As a result, the space inside the housing is made into a lubricating oil atmosphere. A part of the atmosphere rolls into the bearing and appropriately feeds lubricating oil into the bearing. Therefore, the lubrication inside the bearing becomes stable and stable over a long period of time. In addition, the rotational torque is not increased.

It is a figure showing the structure concerning a first embodiment of the present invention. It is a figure which shows the structure which concerns on 2nd embodiment of this invention. It is a figure which shows the structure which concerns on 3rd embodiment of this invention. It is a figure explaining the 1st example of the rolling bearing used for embodiment of this invention. It is a figure explaining the 2nd example of the rolling bearing used for embodiment of this invention. It is a figure explaining the 3rd example of the rolling bearing used for embodiment of this invention. It is a figure explaining the 4th example of the rolling bearing used for embodiment of this invention. It is a figure explaining the 5th example of the rolling bearing used for embodiment of this invention. It is a figure explaining the 6th example of the rolling bearing used for embodiment of this invention. It is a schematic diagram explaining a general electric motor. It is a figure explaining the rolling bearing generally used for an electric motor.

  FIG. 1 shows a first embodiment of a lubricating structure for an electric motor according to the present invention. Since the lubricating structure of the electric motor according to the present invention can be widely applied to the electric motor regardless of the detailed structure of the electric motor, only the main part of the electric motor is shown.

  Basically, in the electric motor according to the present invention, rolling bearings 10 and 20 are disposed between a housing (housing) 4 and the main shaft 1, and a stator (stator) 3 is disposed on the inner periphery of the housing 4. The main shaft 1 has a structure in which a rotor (rotor) 2 is attached. The side end of the housing 4 on the bearing 20 side is closed by a lid (cover) 5, and the main shaft 1 extends from the side end opening of the housing 4 on the opposite bearing 10 side. .

  FIG. 4 shows an example of the rolling bearings 10 and 20 used in the electric motor shown in FIG. The rolling bearings 10 and 20 basically include an outer ring 11 that is used while being fixed to an electric motor casing as a stationary wheel, an inner ring 12 that is used while being fixed to a main shaft of the electric motor, an outer ring 11 and an inner ring 12. A plurality of balls 13 that are rolling elements that are rotatably supported, a cage 14 that holds the balls 13 that are rolling elements apart from each other, and an end opening formed by the outer ring 11 and the inner ring 12 is sealed. Devices 15 and 16. The sealing devices 15 and 16 in this example are shield plates formed from a metal plate. In addition, a grease composition (not shown in FIG. 4) is enclosed in the bearing inner space formed by the outer ring 11, the inner ring 12, and the sealing devices 15, 16 for lubrication of the rolling bearings 10, 20. .

  The first embodiment shown in FIG. 1 is a lubrication structure for a horizontally installed electric motor that is used with its shaft horizontal, and lubricating oil 30 is sealed in the lower part of the casing.

  From this state, when the electric motor is energized, the lubricating oil 30 is atomized (misted) or vaporized by the wind pressure generated by the rotation of the main shaft 1 and the rotor 2 which are rotating parts inside the electric motor. The interior space of the electric motor becomes a lubricating oil atmosphere. Further, when the electric motor is energized, a current flows through the stator 3 and the temperature of the stator 3 is increased by the current, so that the fine particles and vaporization are also promoted. Further, the fine particles and the vaporization are also promoted by the lubricating oil splashed up by vibration or the like when the motor is used.

  On the other hand, the grease composition enclosed in the rolling bearing is separated from the base oil as it is used, or is subjected to shearing caused by agitation inside the rolling bearing, so that the base oil as its component is mainly separated. It may flow out of the bearing.

  The outflow due to the separation of the base oil is a phenomenon that cannot be avoided to some extent as long as the rolling bearing is lubricated with the grease composition. In the short term, even if a small amount of base oil flows out from the internal space of the rolling bearing, it will be in a so-called familiar state and the rotational torque will be stable and there will be no particular problems, but from a long-term perspective, the rolling bearing will be sufficiently lubricated. This will affect the life of the rolling bearing. In other words, in order to improve the life of the rolling bearing in the long term, it is necessary to supplement the flowing base oil portion.

  Here, in anticipation of the separation and outflow of the base oil, if as much grease composition as possible has been sealed inside the rolling bearing from the beginning, the stirring resistance of the grease composition inside the rolling bearing will increase, and the rotational torque will increase. The possibility of causing an increase or rotational torque fluctuation is increased. In addition, the grease composition itself is more likely to flow out of the bearing due to stirring. Therefore, the amount of grease composition that can be initially enclosed in the rolling bearing is determined by the volume of the internal space of the rolling bearing (the volume of the rolling elements and the cage from the volume of the internal space partitioned by the outer ring, inner ring, and sealing device). However, if there is no sealing device, the end face of the outer ring and inner ring is defined as a partition, and in the case of a rolling bearing without a cage, the volume of the cage is not considered. It is.

  In the first embodiment, the oil encapsulated in the electric motor and atomized or vaporized by the rotation of the electric motor, or the oil splashed up inside the housing 4 by vibration or the like is inside the rolling bearings 10 and 20. It is possible to make up for the base oil that enters moderately and separates and flows out from the grease composition originally sealed in the rolling bearings 10 and 20.

  Therefore, it is possible to further extend the life of the rolling bearing. Moreover, since the base oil content is appropriately supplemented as needed, it is possible to cope with high-speed rotation. Furthermore, it is not necessary to excessively increase the amount of the grease composition initially enclosed in the rolling bearing, and it can be used with low torque and low torque fluctuation.

  The double-sided arrows shown in FIG. 4, the description of the inside and the outside indicate the preferred assembly direction of the rolling bearings 10 and 20. The inner side indicates the rotor 2 side from the end of the main shaft 1. Moreover, the rolling bearings 10 and 20 shown in FIG. 4 are made of synthetic resin and include a crown-shaped cage 14 having an opening on one side in the axial direction. That is, in the rolling bearings 10 and 20, it is preferable to assemble the opening of the cage 14 toward the rotor side. As a result, fine particles of the lubricating oil, vaporized components, or splashed lubricating oil generated inside the electric motor can be appropriately taken into the bearing internal space.

  FIG. 2 shows a second embodiment of the present invention, in which the lubricating structure of the present invention is applied to an electric motor used in a so-called vertical position. The arrangement of the lubricating oil 30 is changed from the first embodiment in accordance with the vertical placement. The effects are the same as in the first embodiment.

  FIG. 3 shows a third embodiment of the present invention, in which the lubricating structure of the present invention is applied to an electric motor used in a so-called vertical position. The arrangement of the lubricating oil 30 is changed from the first embodiment in accordance with the vertical placement. In the case of the third embodiment, the lubricant 30 is atomized or vaporized by the rotation of the main shaft 1. In this case, the action on the rolling bearing 10 is reduced, but the structure of the electric motor suffices in terms of cost because the basic structure is sufficient.

  4 to 9 show first to sixth examples of the rolling bearings 10 and 20 used in the first to third embodiments. Since the example shown in FIG. 4 has been described in the first embodiment, description thereof is omitted. Moreover, in FIGS. 5-9, the preferable enclosure form of the grease compositions G1 and G2 is also shown collectively.

  FIG. 5 shows a state in which the grease compositions G1 and G2 are sealed in a preferable sealing form in the rolling bearings 10 and 20 shown in FIG. The double-sided arrows in FIG. 5 and the description of the inside and the outside are the same as those in FIG.

  As shown in FIG. 5, it is preferable to enclose the grease compositions G1 and G2 so as not to touch as much as possible the portions that rotate along with the rotation in the internal space of the rolling bearings 10 and 20. If the electric motor without the lubrication structure of the present invention has such a grease composition enclosed form, the lubrication of the contact portion between the outer ring 12 and the rolling element 13 and between the inner ring 12 and the rolling element 13 becomes poor, which may affect the bearing life. However, if the lubricating structure of the present invention is provided, no particular problem occurs because the lubricating oil is supplied from the inside of the electric motor.

  Furthermore, since the semi-solid grease composition does not intervene in the portion that moves accompanying rotation, the torque is low and torque fluctuation can be reduced.

  FIG. 6 shows a configuration in which only one side of an end opening formed by the outer ring 11 and the inner ring 12 of the rolling bearings 10 and 20 is closed by a sealing device 16. The sealing device 16 is a shield plate made of a metal plate. The explanation of the double-sided arrow, the outside, and the inside is the same as that in FIG. In the case of the example shown in FIG. 6, it is preferable that one side of the sealing device 16 is directed outward and the other side is directed inward. Moreover, about the synthetic resin crown type cage | basket 14, it is preferable to orient | assign an opening part inside. Moreover, the preferable enclosure form of grease composition G1, G2 is shown collectively.

  FIG. 7 shows an example in which both end portions of the rolling bearings 10 and 10 are closed with contact seals which are contact type sealing devices 15 and 16. Moreover, the holder | retainer 14 has shown the example of the metal holder shape | molded from the metal plate. In the form of FIG. 7, the bearing is symmetrical in the axial direction about the rolling element, so the direction of assembling to the electric motor is arbitrary.

  Even if it is a contact seal as shown in FIG. 7, since some lubricating oil penetrate | invades into the inside of the rolling bearings 10 and 20 along a contact part etc., the effect of the lubricating structure of this invention is exhibited.

  FIG. 8 shows an example in which air holes 17 and 18 are provided in the sealing devices 15 and 16 in the example shown in FIG. By providing the air holes 17 and 18, it is possible to reduce the pressure difference inside the electric motor, inside the rolling bearings 10 and 20, and outside, and it is possible to reduce various effects caused by the pressure difference. Furthermore, since the lubricating oil is supplied from the inside of the electric motor through the air hole as well as being transmitted through the contact portion of the contact seal, the effect of the present invention is further exhibited.

  In FIG. 9, the outer sealing device 16 is a contact seal, and the inner sealing device 15 is a non-contact shield plate formed from a metal plate. Since the inner sealing device 15 is non-contact, the lubricating oil is satisfactorily supplied from the inside of the electric motor, and the outer sealing device 16 is used as a contact seal, thus effectively preventing foreign matter from entering from the outside. It is possible to reduce the influence of foreign matter. Moreover, you may provide an air hole in a contact seal as shown in FIG.

  As mentioned above, although the 1st-3rd form by the form of the electric motor and the 1st-6th form by the form of the rolling bearings 10 and 20 were shown, unless the effect of the lubrication structure of the present invention is impaired, it is in these forms. It is not limited. Moreover, it is also possible to apply combining these forms. For example, in one electric motor, the rolling bearing 10 and the rolling bearing 20 may have different sealing devices. Further, for example, different grease compositions can be encapsulated as the grease compositions initially encapsulated in the rolling bearing 10 and the rolling bearing 20.

  In addition, as for the lubricating oil, various lubricating oils can be used without particular limitation as long as they contribute to the lubrication of the rolling bearing. For example, various mineral oils, synthetic oils, animal and vegetable oils, or mixed oils thereof, and oils containing an antioxidant, a rust inhibitor, an extreme pressure agent, an antiwear agent and the like can be used.

  Preferably, mineral oil or synthetic oil is used. More preferably, those which are mutually soluble with the base oil of the grease composition enclosed in the rolling bearing are used. Regarding the viscosity of the lubricating oil, various types can be used from low viscosity to high viscosity. Preferably, the lubricating oil has the same viscosity as that of the base oil of the grease composition enclosed in the rolling bearing.

  In addition, although the lubricating oil is enclosed in the electric motor in the form in which the lubricating oil is enclosed as it is, it is not limited thereto. However, when the lubricating oil is sealed as it is, it is preferable that the amount of the sealed lubricating oil is such that the sealed lubricating oil does not touch the rotating portion inside the electric motor in a steady state posture where the electric motor is placed. When the enclosed lubricating oil touches the rotating part inside the electric motor, there is a considerable agitation resistance, which may lead to power loss of the electric motor.

  Further, as the form of the lubricating oil, it can be enclosed in the electric motor in a form in which the lubricating oil is absorbed by a porous material or a sponge-like oil absorbing material.

  Further, since the stator portion generally has a coil winding portion, lubricating oil may be immersed in the winding, or a part of the stator may be immersed in the lubricating oil. In this case, since the stator generates heat when the stator is energized, the fine particles and vaporization of the lubricating oil are promoted, and the interior of the electric motor can be brought into the lubricating oil atmosphere at an earlier stage.

  The lubricating structure of the electric motor of the present invention further demonstrates its effect at high speed rotation where the dm value indicated by the product of the inner diameter of the rolling bearing and the rotation speed is 700,000 or more. Further, if the dm value is 1 million or more, the effect is further exhibited if it is 1.2 million or more. This is because when the electric motor rotates at a high speed, the rotor also rotates at a high speed and promotes the formation of fine particles and vaporization of the lubricating oil.

  Furthermore, since the lubricating oil is supplied to the rolling bearing in the lubricating structure of the electric motor of the present invention along with the rotation of the electric motor, it is possible to reduce the amount of the grease composition initially sealed. Suitable for high-speed rotation with dm value exceeding 1 million. Specifically, the amount of the grease composition initially sealed in the bearing can be 30% or less of the volume of the internal space of the rolling bearing.

  In a rolling bearing in which the lubrication structure of the present invention is applied to an electric motor used at a high speed rotation with a dm value exceeding 1 million, the non-contact type sealing device is preferable. The cage is preferably made of synthetic resin. Specifically, heat-resistant synthetic resins such as polyamide 46 (PA46), polyamide 66 (PA66), polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), polyetheretherketone (PEEK) are used as the material of the cage. Alternatively, those containing a reinforcing material such as glass fiber (GF) or carbon fiber (CF) in these resins so as to have a blending amount of 10 to 40% by mass can be suitably used. More preferably, a resin composition in which 10 to 40% by mass of glass fiber (GF) is blended with polyamide 46 (PA46) or polyphenylene sulfide (PPS) is used.

  Furthermore, as materials for forming the inner ring, outer ring, and rolling element of the rolling bearing in the lubricating structure of the electric motor of the present invention, a bearing steel such as SUJ2, a metal material such as carburized steel and stainless steel, or an inorganic material such as ceramic. Various materials such as materials can be used. Preferably, bearing steel such as SUJ2 is used. However, when the dm value is used at 1 million or more, the rolling element is preferably made of ceramic.

  Furthermore, since the effect of the lubricating structure of the electric motor of the present invention is exerted by the finely divided or vaporized lubricating oil, it is also a lubricating structure suitable for high temperatures where the finely divided and vaporized are promoted. For example, it can be suitably used even when the operating temperature of the electric motor exceeds 100 ° C.

  The lubrication structure of the electric motor of the present invention can be applied to various electric motors. In particular, because it is suitable for use at high speeds and high temperatures, by applying the lubricating structure of the present invention to an electric motor for driving an electric vehicle or a hybrid vehicle, a highly reliable driving electric motor, and further reliability It is possible to obtain a car with high height.

1 Spindle 2 Rotor
3 Stator (stator)
4 Housing (housing)
5 Lid (cover)
10 Rolling bearing 11 Outer ring (stationary ring)
12 Inner ring (rotating wheel)
13 Rolling elements (balls)
14 Cage 15 Sealing device 16 Sealing device G1 Grease composition G2 Grease composition

Claims (2)

A housing, spindle and, a plurality of rolling bearings which are spaced axially for rotatably holding the spindle against arranged by the housing between the main shaft and the housing in the electric motor having a rotor disposed in the main shaft, and said arranged in a housing the stator,
The rolling bearing includes a stationary ring fixed to the housing, a rotating ring that is fixed to the main shaft, and a plurality of rolling elements rotatably supporting said stationary ring and the rotating ring and said rotating ring are those comprising said a sealing device disposed in the open mouth of the both end portions which are formed in the stationary ring, the grease composition is enclosed in the internal space of the rolling bearing which is defined by the sealing device,
Of the sealing devices, the sealing device disposed inside the rolling elements is a non-contact seal,
Inside the lubrication structure of an electric motor which lubricating oil to the position of the inner and vertically lower than the rolling bearing is characterized in that it is enclosed in the housing. The lubricating oil is in contact with the stator
The lubricating structure for an electric motor according to claim 1.

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