WO2022153689A1 - 回転電機及び車両 - Google Patents

回転電機及び車両 Download PDF

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Publication number
WO2022153689A1
WO2022153689A1 PCT/JP2021/043553 JP2021043553W WO2022153689A1 WO 2022153689 A1 WO2022153689 A1 WO 2022153689A1 JP 2021043553 W JP2021043553 W JP 2021043553W WO 2022153689 A1 WO2022153689 A1 WO 2022153689A1
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WIPO (PCT)
Prior art keywords
bearing
liquid medium
flow path
oil seal
electric machine
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PCT/JP2021/043553
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English (en)
French (fr)
Japanese (ja)
Inventor
哲也 須藤
暁史 高橋
誠 伊藤
Original Assignee
株式会社日立製作所
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Application filed by 株式会社日立製作所 filed Critical 株式会社日立製作所
Publication of WO2022153689A1 publication Critical patent/WO2022153689A1/ja

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K7/00—Disposition of motor in, or adjacent to, traction wheel
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K5/00—Casings; Enclosures; Supports
    • H02K5/04—Casings or enclosures characterised by the shape, form or construction thereof
    • H02K5/10—Casings or enclosures characterised by the shape, form or construction thereof with arrangements for protection from ingress, e.g. water or fingers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K5/00—Casings; Enclosures; Supports
    • H02K5/04—Casings or enclosures characterised by the shape, form or construction thereof
    • H02K5/16—Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields
    • H02K5/173—Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields using bearings with rolling contact, e.g. ball bearings

Definitions

  • the present invention relates to a rotary electric machine and a vehicle.
  • a multi-axis multi-layer rotary electric machine having an outer rotor and an inner rotor for one stator and provided with a plurality of oil cooling chambers for cooling the bearing and the inner rotor is known (see Patent Document 1).
  • the coil of the stator is cooled by the stator cooling water channel. Further, the air gap between the stator and the inner rotor or the outer rotor is opened to atmospheric pressure so as not to interfere with the rotation of the rotor.
  • the water channel lid component assembled to the stator is formed with an extension portion extending to the relative rotation position between the inner rotor side member and the outer rotor side member.
  • a first oil seal and a second oil seal are installed at positions close to the motor shaft between the inner peripheral surface and the outer peripheral surface of the extension portion. The two oil seals are for blocking the communication between the cooling oil in the oil cooling chamber and the air in the stator air chamber.
  • An object of the present invention is to extend the life of the oil seal of a rotary electric machine.
  • the rotary electric machine includes a rotor housing in which a rotor is fixed and a flow path through which a liquid medium flows is formed, and a stator arranged on the inner peripheral side of the rotor.
  • An outer rotor type rotary electric machine including an oil seal arranged between the rotor housing and the stator, the rotor housing has an outer peripheral portion arranged on the outer peripheral side of the stator and the stator.
  • the oil seal includes a fixing portion fixed to the inner peripheral surface of the stator, including an inner peripheral portion arranged on the inner peripheral side of the above and a connecting portion connecting the outer peripheral portion and the inner peripheral portion.
  • An outer rotor type rotary electric machine having a contact portion that is in sliding contact with the inner peripheral portion.
  • the life of the oil seal of the rotary electric machine can be extended.
  • the schematic diagram which shows the structure of the vehicle which concerns on 1st Embodiment.
  • the exploded perspective view which shows the structure of the electric wheel which concerns on 1st Embodiment.
  • the schematic cross-sectional view which shows the structure of the in-wheel motor which concerns on 1st Embodiment. Partially enlarged perspective view of the first embodiment.
  • the state explanatory view of the internal pressure when the rotor is stopped in this invention The state explanatory view of the internal pressure at the time of rotor rotation in this invention.
  • the explanatory view of the internal pressure change at the time of rotor rotation in this invention.
  • Explanatory drawing which shows the relationship between water pressure and gravitational acceleration in this invention.
  • FIG. 2 is a partial cross-sectional view showing the configuration of the second embodiment.
  • a graph showing the relationship between the operating clearance of bearings and fatigue life. The graph which shows the relationship between the inner diameter of a bearing and a bearing clearance.
  • FIG. 3 is a partial cross-sectional view of the third embodiment (projection structure).
  • FIG. 6 is a partial cross-sectional view of the fourth embodiment (recessed structure).
  • FIG. 5 is a partial cross-sectional perspective view of the fifth embodiment.
  • FIG. 6 is a partial cross-sectional perspective view of the sixth embodiment.
  • FIG. 1 is a schematic view showing a configuration of a vehicle 1000 according to a first embodiment of the present invention.
  • the vehicle 1000 of the present embodiment includes a vehicle body frame 1010, a battery base 1020 arranged inside the vehicle body frame 1010, a battery 1030 mounted on the battery base 1020, and wheels (front wheels). And rear wheels).
  • Each wheel left and right front wheels and left and right rear wheels
  • the inverter 150 is mounted on the electric wheel 200.
  • Each electric wheel 200 is connected to the battery 1030 by the power cable PL.
  • the inverter 150 converts the DC power supplied from the battery 1030 into AC power and supplies it to the in-wheel motor 51 mounted on the electric wheel 200.
  • the in-wheel motor 51 mounted on the electric wheel 200 of the present embodiment has a high torque density. Therefore, the in-wheel motor 51 can directly drive the wheels of the vehicle 1000. That is, in the present embodiment, gearless driving of the vehicle 1000, that is, direct drive of the wheels is possible.
  • the vehicle 1000 has the same running performance as a vehicle equipped with a gasoline engine.
  • the vehicle 1000 can operate at a constant speed of 50 km / h in an urban area.
  • the acceleration performance is equal to or better than that of a vehicle equipped with a gasoline engine.
  • the size of the electric wheel 200 of this embodiment will be described.
  • Wheel size is usually expressed in rim diameter.
  • the rim diameter is shown in inches.
  • the electric wheel 200 has, for example, 14 inches (355.6 mm), 15 inches (381 mm), 16 inches (406.4 mm), 17 inches (431.8 mm), 18 inches (457.2 mm), and 19 inches in rim diameter. It can be mounted on (482.6 mm) or 20 inch (508 mm) wheels.
  • the electric wheel 200 having a wheel having a rim diameter of 19 inches (482.6 mm) and a rim width of 8.5 inches (21.6 mm) will be described.
  • FIG. 2 shows an exploded perspective view of the electric wheel 200.
  • the electric wheel 200 of the present embodiment includes a wheel 100 to which a tire is attached and an in-wheel motor 51 attached to the wheel 100.
  • a disc brake 106 that generates a braking force that brakes the wheels is attached to the electric wheel 200.
  • the electric wheel 200 is attached to the vehicle body frame 1010 (see FIG. 1) via the suspension device 110.
  • the suspension device 110 has a knuckle 107 fixed to the in-wheel motor 51 and a lower arm 108 rotatably attached to the knuckle 107.
  • the suspension device 110 includes a shock absorber 109a rotatably connected to the knuckle 107, and a spring 109b attached between the shock absorber 109a and a support member provided on the vehicle body frame 1010.
  • a hub bearing HUB that supports the wheel is arranged near the wheel shaft AX of the wheel 100.
  • the stator 2 is joined to the wheel 100 via the hub bearing HUB.
  • Part of the weight of the vehicle body is supported by the suspension device 110 including the knuckle 107 via the wheel 100, the hub bearing HUB, and the stator 2.
  • an inverter 150 and the like are housed inside the wheel 100.
  • the in-wheel motor 51 mounted on the electric wheel 200 includes a rotor 4, a first oil seal 20A, a second oil seal 20B, a first bearing 11A, and a first bearing 11A, which are attached to the in-wheel motor 51 so as to be able to rotate freely with respect to the stator 2.
  • Two bearings 11B are arranged.
  • the inner connecting portion 4B which is also a rotor cover, is arranged near the knuckle 107.
  • the liquid medium for cooling each component constituting the in-wheel motor 51 is supplied into the in-wheel motor 51 by a pump (not shown) provided outside the electric wheel 200.
  • the pipe through which the liquid medium flows is taken out from the vehicle body side side surface of the electric wheel 200 and connected to a heat exchanger (not shown) arranged at the front portion of the vehicle body.
  • the liquid medium is cooled by an air-cooled or water-cooled heat exchanger.
  • FIG. 3 shows a schematic cross-sectional view of the in-wheel motor 51.
  • FIG. 3 shows the arrangement of the main structural parts of the in-wheel motor 51, for example, the stator core 2X, the rotor core 4X, the gap 7, the first bearing 11A, the second bearing 11B, the first oil seal 20A, and the second oil seal 20B. Shown.
  • the peripheral structure of the hub bearing HUB of the in-wheel motor 51 is not shown.
  • the in-wheel motor 51 includes a stator 2 and a rotor 4.
  • the stator 2 includes a cylindrical stator core 2X, a plurality of coils 2Z wound around the stator core 2X, and a stator housing 2W that supports the stator core 2X.
  • the rotor 4 includes a rotor core 4X that is rotatably arranged with respect to the stator core 2X via a gap 7, and a rotor housing 4W that supports the rotor core 4X.
  • a plurality of slots (not shown) parallel to the central axis direction of the stator core 2X are formed on the outer peripheral portion of the stator core 2X.
  • the plurality of slots are formed at equal intervals in the circumferential direction of the stator core 2X.
  • the coil 2Z is housed in the slot.
  • Teeth 2T is formed between the slots (see FIGS. 11 and 12).
  • the plurality of teeth 2T are integrated with the annular core back 2Q (see FIG. 11). That is, the stator core 2X is a core in which a plurality of teeth 2T and a core back 2Q are integrally molded.
  • a split core is used in the circumferential direction.
  • the teeth 2T guides the rotating magnetic field generated by the coil 2Z to the rotor core 4X, and generates a rotational torque in the rotor core 4X.
  • Coil 2Z is formed by connecting a plurality of conductor pieces.
  • the conductor piece is formed by punching a plate of a low resistance conductor such as copper.
  • the coil 2Z may be formed by a flat wire having a rectangular cross section.
  • the coil 2Z is accommodated in a slot of the stator core 2X in a layered manner in the radial direction.
  • the radial direction refers to the radial direction of the cylindrical rotary electric machine.
  • the axial direction refers to the rotating shaft on which the rotor 4 of the rotating electric machine rotates.
  • the circumferential direction refers to the circumferential direction of the stator 2 or rotor 4 having a cylindrical shape.
  • the rotary electric machine refers to an in-wheel motor that can be incorporated in the wheel 100.
  • the coil 2Z has an in-slot conductor arranged in the slot of the stator core 2X, and a coil end portion protruding out of the slot from both ends of the stator core 2X.
  • the coil end portion arranged on one end side (outside the vehicle) of the stator core 2X is referred to as the first coil end portion 2ZA
  • the coil end portion arranged on the other end side (vehicle body side) of the stator core 2X is referred to as the second coil end portion 2ZB. It is written as.
  • the first coil end portion 2ZA and the second coil end portion 2ZB generate heat during the operation of the in-wheel motor 51 and become hot.
  • the first coil end portion 2ZA and the second coil end portion 2ZB are arranged in the liquid medium passage 15 in which the liquid medium is housed, and are cooled by the liquid medium.
  • the stator housing 2W includes a cylindrical main body 2C, a first end bracket 2A fixed to an opening on one end side of the main body 2C, and a second end bracket 2B fixed to an opening on the other end side of the main body 2C. , Equipped with.
  • the stator core 2X is shrink-fitted to the outer peripheral portion of the main body 2C, and is fitted and fixed by press-fitting or the like.
  • the main body 2C is formed by a die casting method using a light metal such as aluminum or magnesium alloy, for example.
  • the main body 2C may be formed by a layered manufacturing method such as a 3D printer molding method.
  • a 3D printer molding method By adopting the additive manufacturing method, the degree of freedom in the shape of the main body 2C is improved.
  • the inside of the main body 2C is a space, and the inverter 150 is accommodated (see FIG. 2). As a result, a motor unit having a mechanical and electrical integrated structure in which the in-wheel motor 51 and the inverter 150 (power conversion device) are integrated is formed.
  • a plurality of permanent magnets are fixed to the rotor core 4X.
  • the permanent magnet forms the field pole of the rotor 4.
  • the rotor 4 rotates about the wheel shaft AX by guiding the rotating magnetic field generated by the coil 2Z.
  • the rotor housing 4W includes an inner lid 4BE, an outer peripheral portion 4C, and an outer lid 4AE.
  • the inner lid 4BE includes an inner inner peripheral portion 4SB and an inner connecting portion 4B.
  • the outer lid 4AE includes an outer inner peripheral portion 4SA and an outer connecting portion 4A.
  • the outer peripheral portion 4C and the outer lid 4AE are often formed by integral molding, in which case the outer peripheral portion 4C and the outer lid 4AE have a bottomed cylindrical shape.
  • the outer peripheral portion 4C of the rotor housing 4W and the outer lid 4AE may be separated in relation to the allowable dimensional accuracy and rigidity, the assemblability of the parts to be used, and the like.
  • the outer peripheral portion 4C and the outer lid 4AE that are divided are collectively referred to as a housing body 4CE.
  • the case of the outer peripheral portion 4C and the outer lid 4AE formed by integral molding is also referred to as a housing body 4CE.
  • the rotor core 4X is shrink-fitted, press-fitted, or the like to fit and fix the rotor core 4X to the central inner peripheral portion of the housing body 4CE facing the stator core 2X. That is, the rotor housing 4W including the housing body 4CE rotates together with the rotor core 4X.
  • the housing body 4CE is formed of, for example, a light metal such as aluminum die-cast or a lightweight structural material such as carbon fiber reinforced plastic (CFRP).
  • CFRP carbon fiber reinforced plastic
  • the housing body 4CE is formed as one part by an integral molding method having high processing accuracy such as a tub-shaped die casting method. Is preferable.
  • the housing body 4CE may be manufactured by carving out from one material.
  • the first bearing 11A and the second bearing 11B that connect the outer peripheral portion of the main body 2C and the housing main body 4CE are arranged between the outer peripheral portion of the main body 2C and the central inner peripheral portion of the housing main body 4CE. Since the first bearing 11A and the second bearing 11B have different diameter sizes but the same configuration, the first bearing 11A and the second bearing 11B are collectively referred to as the bearing 11 below. Further, the first rolling element 10A of the first bearing 11A and the second rolling element 10B of the second bearing 11B are collectively referred to as a rolling element 10.
  • the first bearing 11A is arranged on one end side in the axial direction of the stator core 2X (right side in the drawing), and the second bearing 11B is arranged on the other end side in the axial direction of the stator core 2X (left side in the drawing).
  • a first inner ring fixing portion 2LA into which the first inner ring of the first bearing 11A is gap-fitted is formed on one end side in the axial direction of the main body 2C, and the other end of the outer peripheral portion of the main body 2C in the axial direction.
  • a second inner ring fixing portion 2LB into which the second inner ring of the second bearing 11B is gap-fitted is formed.
  • a first outer ring fixing portion 4MA to which the first outer ring of the first bearing 11A is press-fitted is formed on one end side in the axial direction of the housing body 4CE, and a second bearing 11B is formed on the other end side in the axial direction of the housing body 4CE.
  • a second outer ring fixing portion 4MB is formed in which the second outer ring of the above is press-fitted and fixed.
  • the weight of the rotor 4 itself is not applied. This is because, as described above, the weight of the vehicle body is transmitted to the wheel axle AX via the hub bearing HUB, and is finally supported by the suspension device 110.
  • the rotor 4 need only have rigidity that does not deform due to rotational torque.
  • the in-wheel motor 51 is assembled as follows, for example. First, the first bearing 11A is press-fitted and fixed to the first outer ring fixing portion 4MA of the housing body 4CE of the rotor housing 4W. After that, the stator 2 is inserted into the housing main body 4CE, and the first inner ring fixing portion 2LA on the outer peripheral portion of the main body 2C is fitted into the first inner ring of the first bearing 11A.
  • the second bearing 11B is fitted between the second outer ring fixing portion 4MB of the housing main body 4CE and the second inner ring fixing portion 2LB of the main body 2C.
  • the in-wheel motor 51 in which the stator 2 is arranged is assembled in the housing body 4CE.
  • the liquid medium path 15 of this embodiment will be described.
  • a liquid medium path 15 is formed between the stator 2 and the rotor 4.
  • the liquid medium path 15 is formed inside the gap 7 between the stator core 2X and the rotor core 4X, the outer connection portion 4A of the housing body 4CE of the rotor housing 4W, and the axial end portion of the stator housing 2W. It has a flow path 15A.
  • the liquid medium path 15 includes an inner internal flow path 15B formed between the inner connecting portion 4B of the rotor housing 4W and the stator housing 2W, the bearing inner 11AS of the first bearing 11A, and the bearing of the second bearing 11B. It has an internal 11BS and.
  • the liquid medium path 15 is also referred to as a flow path 15.
  • the rotor housing 4W is arranged so as to cover the outside of the stator 2 via the bearing 11, and a space is provided between the two.
  • the rolling elements 10 of the first bearing 11A and the second bearing 11B and the coil end portion of the coil 2Z are arranged in the flow path 15 in which the liquid medium is housed.
  • a liquid medium flows inside the outer inner flow path 15A and the inner inner flow path 15B as the rotor 4 rotates.
  • the gap 7 is a narrow space in which the stator core 2X and the rotor core 4X face each other.
  • the rotating magnetic field generated by the stator core 2X electromagnetically acts on the rotor core 4X through the gap 7, and generates torque in the rotor 4.
  • a liquid medium, not air, is housed in the gap 7 of the in-wheel motor 51 to cool the periphery of the gap 7.
  • the outer inner flow path 15A is arranged between the outer lid 4AE and the first end bracket 2A on the outer side (outside of the vehicle) of the housing body 4CE.
  • a first oil seal 20A is arranged between the outer lid 4AE and the first end bracket 2A.
  • the inner inner flow path 15B is a space between the inner lid 4BE located inside the rotor housing 4W (on the vehicle body side) and the stator housing 2W.
  • a second oil seal 20B is arranged between the inner lid 4BE and the second end bracket 2B.
  • the outer inner flow path 15A and the inner inner flow path 15B have a thin donut-shaped structure centered on the wheel shaft AX of the in-wheel motor 51.
  • the liquid medium is housed inside the outer inner flow path 15A and the inner inner flow path 15B. Next, the oil seal will be described.
  • the position and fixing method of the first oil seal 20A are as follows.
  • the outer inner peripheral portion 4SA on the outer side of the vehicle of the outer lid 4AE is formed as if the inner diameter side end portion of the outer connecting portion 4A is folded back from the outer surface of the vehicle to the inner diameter side.
  • the outer inner peripheral portion 4SA is integrally and continuously connected to the outer connecting portion 4A, and is formed as a hollow cylindrical shaft centered on the wheel shaft AX.
  • the first fixing portion 20AT of the shaft rotation type first oil seal 20A in which the contact portion slides and contacts the contacted surface is fixed to the first seal mounting portion 2AK of the first end bracket 2A, and the first fixing portion 20AT thereof is fixed.
  • the contact portion 20AS is slidably contacted with the surface of the outer inner peripheral portion 4SA.
  • the first oil seal 20A is arranged on the inner peripheral side of the first bearing 11A.
  • the position and fixing method of the second oil seal 20B are as follows.
  • the inner inner peripheral portion 4SB on the vehicle body side of the inner lid 4BE is formed as if the inner diameter side end portion of the inner connecting portion 4B is folded back from the surface on the vehicle body side to the inner diameter side.
  • the inner inner peripheral portion 4SB is integrally and continuously connected to the inner connecting portion 4B, and is formed as a hollow cylindrical shaft centered on the wheel shaft AX.
  • the second fixing portion 20BT of the shaft rotation type second oil seal 20B in which the contact portion slides and contacts the contacted surface is fixed to the second seal mounting portion 2BK of the second end bracket 2B, and the second fixing portion 20BT thereof is fixed.
  • the contact portion 20BS is slidably contacted with the surface of the inner inner peripheral portion 4SB.
  • the second oil seal 20B is also arranged on the inner peripheral side of the second bearing 11B.
  • the model of the oil seal is specified in the Japanese Industrial Standards Organization (JIS B 2402), the Japanese Automotive Standards Organization (JASO F 401), or the International Organization for Standardization (ISO 6194).
  • JIS B 2402 Japanese Industrial Standards Organization
  • JASO F 401 Japanese Automotive Standards Organization
  • ISO 6194 International Organization for Standardization
  • six types of ISO type oil seals, Type 1 to Type 6 are known as shaft rotation type oil seals.
  • bearing manufacturers sell shaft rotation type products with different forms, which can be applied to the present invention.
  • the rotary sliding portion that contacts the first oil seal 20A of the outer inner peripheral portion 4SA or the rotary sliding portion that contacts the second oil seal 20B of the inner inner peripheral portion 4SB is plated with hard alumite or hard chrome. It is preferable to apply the surface treatment of.
  • the first oil seal 20A cuts off the flow path 15 of the in-wheel motor (rotary electric machine) 51 from the outside air, and forms an outer inner flow path 15A sealed between the outer connection portion 4A and the first end bracket 2A. Will be done.
  • FIG. 4 shows a partially enlarged view of the structure near the first oil seal 20A.
  • the first fixing portion 20AT of the first oil seal 20A is attached to the first seal attaching portion 2AK of the first end bracket 2A on the inner peripheral side near the wheel shaft AX.
  • the first oil seal 20A has the outer inner circumference of the first contact portion 20AS due to the pressure of the liquid medium in the outer inner flow path 15A surrounded by the outer peripheral portion 4C (not shown), the outer connecting portion 4A and the outer inner peripheral portion 4SA.
  • the structure is such that the seal pressure resistance is increased by being pressed against the inner surface of the portion 4SA. That is, if the peripheral liquid medium has a low pressure, the pressing force at the first contact portion 20AS becomes small, and if the peripheral liquid medium has a high pressure, the pressing force becomes relatively large. Further, when the rotor 4 (see FIG. 3) including the outer inner peripheral portion 4SA and the outer connecting portion 4A rotates around the wheel shaft AX, a centrifugal force 15CF is generated in the liquid medium of the outer inner flow path 15A.
  • FIG. 5 is a schematic view showing the internal pressure distribution in the outer internal flow path 15A when the rotor 4 is stopped.
  • the flow path 15 including the outer inner flow path 15A is surrounded by the outer peripheral portion 4C, the outer connection portion 4A, and the outer inner peripheral portion 4SA with the stator housing 2W fixed to the hub bearing HUB on the inside. Even when the rotor 4 (see FIG. 3) rotating around the wheel shaft AX is stopped, the liquid medium is supplied to the flow path 15 from the outside at a predetermined pressure with respect to the liquid medium inlet 14A of the flow path 15. Has been done.
  • the outer inner flow path 15A is located on the upstream side of the flow path 15, the internal pressure corresponding to the flow path pressure loss is generated substantially evenly with respect to the inner surface of the outer inner flow path 15A. That is, the internal pressure in the vicinity of the first oil seal 20A and the internal pressure on the outer peripheral side of the outer internal flow path 15A are the same.
  • FIG. 6 is a schematic view showing the internal pressure distribution in the outer internal flow path 15A when the rotor 4 rotates around the wheel shaft AX passing through the hub bearing HUB.
  • the rotor 4 see FIG. 3 including the outer peripheral portion 4C, the outer connecting portion 4A, and the outer inner peripheral portion 4SA rotates, a centrifugal force of 15CF is generated with respect to the liquid medium.
  • the internal pressure of the flow path pressure loss and the pressure due to the centrifugal force 15CF are added up at each part of the inner surface of the outer internal flow path 15A. Therefore, in the outer internal flow path 15A, the inner peripheral side has a relatively low pressure and the outer peripheral side has a high pressure.
  • FIG. 7 is a schematic view showing a change in internal pressure generated in the outer internal flow path 15A as the rotor 4 (see FIG. 3) rotates around the wheel shaft AX passing through the hub bearing HUB.
  • the liquid medium contained in the outer internal flow path 15A is in contact with the surfaces of the housing body 4CE and the stator housing 2W. Since the liquid medium has a larger surface area in contact with the housing body 4CE than the stator housing 2W, as a result, the liquid medium is linked to the movement of the housing body 4CE, and finally the liquid medium rotates in the same direction as the rotor 4. (See Fig. 3).
  • the broken line in the graph of FIG. 7 shows the average pressure of the broken line portion from the wheel shaft AX in the upper segment to the outer peripheral direction.
  • the average pressure of the liquid medium increases as the distance from the wheel shaft AX increases in the radial direction. Its action is as follows.
  • the centrifugal force 15CF (see FIGS. 4 and 6) applied to the liquid medium is defined by the following formula (1).
  • the notation and unit of variables in the following formula are as follows.
  • F Centrifugal force (N), m: Mass (kg), r: Rotation radius (m), ⁇ : Rotation angular velocity (rad / s), N: Rotation speed (min -1 ), a: Centrifugal acceleration (m /) s 2 ), g: Gravity acceleration (m / s 2 ).
  • the relative centrifugal acceleration RCF Reactive Centrifugal Force
  • the water pressure difference can be calculated from the difference between the specific gravity of water and the water depth by the following equation (4) (see FIG. 8 showing the relationship between hydrostatic pressure, and in calculating this equation, the specific gravity of the liquid medium is almost the same as that of water. It is assumed to be a degree.)
  • P pressure (Pa)
  • ⁇ water density (kg / m 3 ).
  • the material and form of the first oil seal 20A may be a rubber-integrated type, or may be a metal ring when the internal pressure is high.
  • rubber, PTFE or the like can be used as the material of the first contact portion 20AS of the first oil seal 20A.
  • the first oil seal 20A is mounted on the outer internal flow path 15A side with its opening side facing.
  • the first oil seal 20A does not only have a function of preventing scattering of the liquid medium enclosed inside and sealing dust, but also allows the liquid medium to flow in the vicinity of the first oil seal 20A and has an internal pressure. It is preferable to use a structure in which the pressing force of the first contact portion 20AS is increased.
  • the liquid medium it is not necessary for the liquid medium to circulate in the outer internal flow path 15A, and the liquid medium may stay in the vicinity of the first oil seal 20A. However, it goes without saying that if the liquid medium circulates, the cooling efficiency of the first contact portion 20AS is improved.
  • the relationship between the second oil seal 20B provided at substantially the same radial position with respect to the wheel shaft AX and the inner internal flow path 15B is also the same, and the second oil seal 20B second as the rotor 4 rotates.
  • the internal pressure near the contact portion 20BS tends to decrease.
  • the pressure in the inner inner flow path 15B in contact with the second oil seal 20B is relatively lower than that in the outer inner flow path 15A due to the internal pressure loss.
  • FIG. 9 is a schematic view showing the relationship between the pressing force of the first oil seal 20A at the first contact portion 20AS and the rotation speed of the rotor 4 (see FIG. 3) including the housing body 4CE.
  • the pressing force of the first oil seal 20A at the first contact portion 20AS is the sum of the mechanical binding force of the annular spring and the pressing force of the internal pressure of the liquid medium (see equation (5) in FIG. 9).
  • the rotor housing 4W (outer lid 4AE, outer peripheral portion 4C, inner lid 4BE) rotates around the wheel shaft AX passing through the hub bearing HUB, so that a centrifugal force of 15CF is generated in the liquid medium (FIG. 4). , See FIG. 6), the internal pressure near the first oil seal 20A decreases.
  • the bearing 11 is arranged between the stator 2 and the housing body 4CE.
  • the bearing inner portions 11AS and 11BS are spaces formed between the inner ring and the outer ring of the bearing (see FIGS. 3 and 13).
  • the rolling elements 10 are arranged inside the bearings 11AS and 11BS.
  • the bearing inner 11AS, the gap 7, and the outer inner flow path 15A of the first bearing 11A communicate with each other.
  • the inner bearing 11BS, the gap 7, and the inner inner flow path 15B of the second bearing 11B communicate with each other.
  • the rolling elements 10 of the bearing 11 and the outer rings 10A OR and 10B OR rotate with respect to the stator 2 fixed to the vehicle body frame 1010 as the housing body 4CE rotates (see FIGS. 1, 2, and 13). ). Since the bearing internal 11AS and 11BS of the bearing 11 are a part of the flow path 15, the rolling elements 10 of the bearing internal 11AS and 11BS are in contact with the liquid medium. Therefore, the rolling element 10 is directly cooled by the liquid medium. Some liquid media rotate in the circumferential direction as the bearing 11 rotates. In this way, the bearing internal 11AS and 11BS are configured as a part of the flow path 15. In this way, the liquid medium is accommodated in the plurality of spaces, that is, the flow path 15 including the gap 7, the outer inner flow path 15A, the inner inner flow path 15B, the bearing inner 11AS, and 11BS.
  • Liquid medium inlet and liquid medium outlet As shown in FIG. 3, in the present embodiment, a supply through hole for supplying the liquid medium to the inside of the in-wheel motor 51 is directly below the first coil end portion 2ZA. There is one place. The outside of the supply through hole is the external intake 13A, and the inside is the liquid medium inlet 14A of the flow path 15. The liquid medium inlet 14A is arranged near the first coil end portion 2ZA of the flow path 15.
  • a discharge through hole for discharging the liquid medium supplied from the liquid medium inlet 14A to the inside of the in-wheel motor 51 to the outside is provided at one place directly under the second coil end portion 2ZB.
  • the outside of the discharge through hole is the external outlet 13B, and the inside is the liquid medium outlet 14B of the flow path 15.
  • the distance between the first bearing 11A and the first coil end portion 2ZA is longer than the distance between the liquid medium inlet 14A and the first coil end portion 2ZA, and the distance between the second bearing 11B and the second coil end portion 2ZB The distance between them is set to be longer than the distance between the liquid medium outlet 14B and the second coil end portion 2ZB.
  • the bearing 11 in contact with the liquid medium is less likely to be mixed with unnecessary foreign matter from the outside, which is preferable.
  • the external intake 13A and the external outlet 13B are provided at positions shifted by about 180 degrees in the circumferential direction.
  • a modified example of the arrangement configuration can be considered, such as the positional relationship between the liquid medium outlet 14B and the liquid medium inlet 14A being substantially the same position (about 0 degrees) in the circumferential direction or substantially opposite positions (about 180 degrees). See FIG. 13).
  • the liquid medium is accommodated in the gap 7 communicating inside the in-wheel motor 51, the bearing internal 11AS, 11BS (see FIG. 8), the outer internal flow path 15A, the inner internal flow path 15B, and the like. ..
  • the first oil seal 20A is arranged inside the outer inner flow path 15A. Further, a second oil seal 20B is arranged inside the inner inner flow path 15B.
  • a pipe may be connected to the external intake 13A, the external outlet 13B may be opened, and the liquid medium may be supplied until the inside is filled.
  • a pipe or a hose is connected to the external outlet 13B to form a circulation path with a heat exchanger or the like.
  • Pressure is applied to the liquid medium by the pump and supplied to the flow path 15.
  • the liquid medium flows through the flow path 15, further exits from the liquid medium outlet 14B and the external outlet 13B, and circulates with the external heat exchanger.
  • the liquid medium supplied to the inside of the in-wheel motor 51 from the liquid medium inlet 14A becomes a liquid medium flow 15R from the first coil end portion 2ZA to the second coil end portion 2ZB and flows inside the gap 7.
  • the space of the gap 7 through which the liquid medium flows in the axial direction is a part of the flow path 15.
  • the external intake 13A and the external outlet 13B are provided in the vicinity of the first coil end portion 2ZA and the second coil end portion 2ZB, respectively, with respect to the flow path 15. That is, an external intake 13A and an external outlet 13B are provided in the space on the inner peripheral side of the main body 2C.
  • the external heat exchanger (not shown) and the external connection port 13 are connected by a pipe or a hose.
  • the flow path 15 is formed so that each rolling element (ball) 10 of the two bearings 11 arranged between the stator 2 and the rotor housing 4W is in contact with the liquid medium.
  • the rolling element 10 of the bearing 11 moves in the circumferential direction while rotating at the bearing internal 11AS and 11BS along the rotation direction of the housing body 4CE. Therefore, the liquid medium in the vicinity of the rolling element 10 in the bearing internals 11AS and 11BS moves in the circumferential direction in the same manner as the rolling element 10.
  • the liquid medium inside the bearings 11AS and 11BS absorbs frictional heat and the like generated by the rolling elements 10 themselves.
  • the liquid medium contained in the outer inner flow path 15A and the inner inner flow path 15B hardly moves significantly in the axial direction inside the in-wheel motor 51.
  • the in-wheel motor 51 rotates, the liquid medium is drawn to the inner connecting portion 4B or the outer connecting portion 4A in contact with the liquid medium.
  • the liquid medium contained in the outer inner flow path 15A and the inner inner flow path 15B rotates to some extent in the circumferential direction. In that case, heat is dissipated from the liquid medium to the outside via the outer connecting portion 4A and the inner connecting portion 4B.
  • the flow path 15 has a function of efficiently cooling the in-wheel motor 51 having a high output.
  • the liquid medium flows in a certain direction from the first coil end portion 2ZA to the second coil end portion 2ZB through the thin cylindrical gap 7.
  • the liquid medium cools the stator core 2X, the rotor core 4X, and the like.
  • the in-wheel motor 51 of the present embodiment outputs a high torque by passing a large current through the coil 2Z. Therefore, since the coil 2Z generates heat due to the Joule loss, the temperatures of the coil 2Z and the stator core 2X are more likely to rise than those of the rotor core 4X.
  • the liquid medium is constantly flowed through the gap 7 between the stator core 2X and the rotor core 4X.
  • the liquid medium is taken in from the external intake 13A and supplied to the inside of the flow path 15 from the liquid medium inlet 14A. Since the liquid medium is pumped by a pump placed outside, the liquid medium has a relatively higher pressure at the position of the liquid medium inlet 14A than that of the liquid medium outlet 14B side.
  • the liquid medium continuously flows in the cylindrical gap 7 in the axial direction.
  • the liquid medium can continuously absorb the heat generated in the vicinity of the stator core 2X and the coil 2Z and exhaust the heat to the outside.
  • the liquid medium flows through the cylindrical gap 7 from the first coil end portion 2ZA to the second coil end portion 2ZB. Due to the flow of the liquid medium, the liquid medium absorbs heat generated by the stator core 2X and the like, the temperature of the liquid medium rises, and the temperature of the liquid medium near the second bearing 11B rises, whereby the temperature of the second bearing 11B rises. It becomes higher than the temperature of the first bearing 11A.
  • the internal gap of the second bearing 11B becomes relatively smaller than the internal gap of the first bearing 11A due to thermal expansion.
  • the life of the second bearing 11B may be shorter than the life of the first bearing 11A because the internal gap of the second bearing 11B is narrowed due to thermal expansion.
  • the diameter of the second bearing 11B is set to be larger than the diameter of the first bearing 11A. As a result, the life of the second bearing 11B is improved.
  • the gap 7 is a first axial flow path through which the liquid medium flows in the axial direction.
  • the first bearing 11A is arranged on the liquid medium inlet 14A side of the first axial flow path, and the second bearing 11B is arranged on the liquid medium outlet 14B side of the first axial flow path, and the second bearing 11B is arranged.
  • the inner diameter of the first bearing 11A is set to be larger than the inner diameter of the first bearing 11A.
  • the first bearing 11A and the second bearing 11B arranged between the housing main body 4CE and the main body 2C. Since the diameter of the first bearing 11A is larger than that of the first oil seal 20A described above, the peripheral speed is faster and the heat generation tends to be larger. Therefore, the first bearing 11A is lubricated with a liquid medium and cooled. The same applies to the second oil seal 20B and the second bearing 11B. Therefore, it is preferable to use large-diameter and thin bearings for the first bearing 11A and the second bearing 11B. Thin bearings have merits such as a smaller bearing width and lighter weight than general bearings. Generally, the larger the diameter of a bearing, the larger the cross section of the rolling element 10.
  • the thin bearing is designed to have a larger bearing diameter while maintaining a small cross-sectional area of the rolling element. Therefore, since the cross section of the rolling element of the thin bearing is smaller than the diameter of the rolling element, the allowable load and the allowable peripheral speed are also smaller than those of a general bearing.
  • the thin bearing has an advantage that the entire bearing is small and lightweight.
  • the thin bearing applicable to this embodiment has an inner diameter of about 20 cm or more and a rolling element having a diameter of about several mm.
  • the weight of the vehicle body is separately supported by the hub bearing HUB (see FIGS. 2 and 3). That is, the vehicle weight is not directly applied to the first bearing 11A and the second bearing 11B used in the present embodiment.
  • These two bearings 11 support the weight of the rotor 4 to which the bearings 11 are connected.
  • the structure and characteristics of the bearing 11 will be described later.
  • the bearing 11 is not subjected to a radial load or a thrust load, or even if a radial load or a thrust load is applied, the bearing 11 having a small cross-sectional area of the rolling element 10 is selected as long as the load is small. Can be used.
  • miniaturization and weight reduction are important technical elements, so it is important to select a bearing 11 having a minimum cross-sectional area of the rolling element 10 as small as possible.
  • the internal gap of a radial bearing refers to the amount of movement when one of the inner ring or the outer ring is fixed and the other is moved.
  • the amount of movement when the inner ring or outer ring is moved in the radial direction is called the radial internal gap.
  • the effective gap of the bearing is the amount of reduction of the gap due to the fitting of the bearing and the amount of reduction of the gap due to the temperature difference between the inner ring and the outer ring from the gap (true gap) before mounting the bearing. It is a thing.
  • the operating gap is the effective gap plus the amount of increase in the gap due to the load applied to the bearing.
  • the first bearing 11A of the present embodiment is arranged at a position closer to the liquid medium inlet 14A than the second bearing 11B.
  • the approximate size of the first rolling element 10A of the first bearing 11A is a cross section of 1.27 cm (1/2 inch) square and an inner diameter of 35.6 cm (14 inches).
  • the bearing interiors 11AS and 11BS including the rolling elements 10 and the like of the bearing 11 are cooled by the liquid medium (see FIG. 13).
  • the rolling elements 10 of the two bearings 11 are arranged so as to be in contact with the liquid medium of the flow path 15.
  • the forced liquid medium lubrication method for passing the liquid medium in the axial direction of the bearing 11 will be described later.
  • the first bearing 11A and the second bearing 11B are separately provided with a cooling oil seal portion, but a seal type bearing may also be used. Further, in order to narrow the gap 7 between the stator 2 and the rotor 4, it is preferable that the first bearing 11A and the second bearing 11B are arranged at positions as close as possible to the stator core 2X and the rotor core 4X. If a seal type bearing is adopted, it is not necessary to separately install a seal in addition to the bearing, so that the number of parts can be reduced.
  • the seal type bearing has a longer shaft length, and its pressure resistance is lower than that of the seal separate type bearing. Further, since heat generated by the rotation of the rolling element 10 of the bearing 11 and heat generated by the friction of the seal portion are generated at the same location, it is preferable to combine the bearing with a separate seal and the seal when comparing the whole.
  • Grease lubrication is also used as a cooling method for the bearing 11, but grease lubrication is not positively used in the present embodiment.
  • the bearing steel SUJ2 As the material of the bearing used in this embodiment, it is preferable to use the bearing steel SUJ2. SUS may be used instead of SUJ2. A metal such as SUS is used for the rolling element 10. Since the coefficient of thermal expansion of a ceramic rolling element is smaller than that of a metal, it is not easily affected by a temperature rise, but it is not unapplicable.
  • the diameter of the first bearing 11A is close to the rim diameter of the wheel.
  • the true clearance inside the radial before assembling the bearing 11 can be selected from the range of about 80 to 130 ⁇ m. However, depending on the material of the main body 2C and the temperature setting of the liquid medium, it is possible to select another series of bearings having different inner diameter sizes.
  • the second bearing 11B used in the present embodiment has a large diameter, and the bearing gap (true gap before mounting) is set large in advance. Therefore, it is easy to absorb the thermal expansion of the second rolling element 10B or the like of the second bearing 11B based on the local heat generation generated by the second bearing 11B.
  • the setting of the operating gap will be described with reference to FIG.
  • the condition at which the fatigue life curve peaks is when the operating gap is negative. That is, it is often used by setting the operating gap to be slightly narrower than 0.
  • the curves (a) and (b) of FIG. 14 are for the case where the load conditions for the same bearing are different by about 6 times, and the life shows the maximum value when the operating gap is about -3 to -8 ⁇ m. ..
  • the operating clearance is set to the maximum value of the fatigue life curve in the region of 0 or less with the aim of extending the life of the bearing, the fatigue life curve will be maximized due to the dimensional variation of parts and assembly accuracy.
  • the actual operating gap may shift to the minus side from the value. Then, the life of the bearing deteriorates sharply.
  • the second bearing 11B is set in advance so that the operating gap is 0 or more, as shown by the range of the arrow in (c).
  • the bearing tolerance will be described with reference to FIG. As shown in FIG. 15, the larger the outer diameter and inner diameter of the bearing, the larger the tolerance width.
  • the setting of the operating clearance of the bearing is not a plus or minus tolerance, but the lower limit of the setting of the operating clearance is set to 0. Set the operating clearance in consideration of the tolerance of the bearing to be used. As a result, the target value for setting the operating clearance of the bearing is larger than the general value.
  • the bearing inner parts 11AS and 11BS including the rolling elements 10 of the two bearings 11 are arranged in the flow path 15 and are in contact with the liquid medium.
  • the liquid medium absorbs heat generated in the vicinity of the stator core 2X where the temperature rises remarkably inside the in-wheel motor 51, passes through the liquid medium outlet 14B, and exits from the external outlet 13B. At that time, the liquid medium that absorbs the heat generated in the vicinity of the stator core 2X becomes relatively hot as it passes through the gap 7 and progresses toward the outlet side rather than the inlet side.
  • the second bearing 11B in contact with the liquid medium which is relatively hotter than the liquid medium inlet 14A side, is exposed to the temperature of the liquid medium in contact with the second bearing 11B in addition to the heat generated by the rotational operation of the second bearing 11B itself. Will be. That is, in the present embodiment, the temperature of the second bearing 11B tends to be higher than that of the first bearing 11A during operation.
  • the second inner ring 10B IR of the second bearing 11B is in direct contact with the main body 2C. That is, the second inner ring 10B IR of the second bearing 11B is directly affected by the heat conduction from the main body 2C. As a result, the inner diameter of the second bearing 11B becomes larger than the inner diameter of the first bearing 11A when the in-wheel motor 51 is operated due to the temperature rise.
  • holes 2H are concentrically provided in the circumferential direction of the second end bracket 2B from the stator core 2X. (See FIG. 16).
  • the hole 2H is located between the stator core 2X and the second bearing 11B in the radial direction.
  • the hole 2H is provided as a hole penetrating in the axial direction on the side surface of the second end bracket 2B within a range that does not affect the strength and rigidity of the component.
  • the heat conduction area of the main body 2C is reduced by the hole 2H, the heat of the coil 2Z is less likely to be transferred to the second bearing 11B.
  • the inner internal flow path 15B and the gap 7 side are communicated with each other, and convection of the liquid medium occurs inside. Since the liquid medium is more in contact with the second bearing 11B due to this convection, the second bearing 11B is easily cooled. In this way, the inside of the hole 2H becomes a part of the flow path 15.
  • the shape of the hole 2H may be a round hole or a long hole. Further, if a hole is provided at a position where the gap 7 can be seen, it can be used as a hole for inserting a protective plate into the gap 7 when assembling the stator and the rotor.
  • the temperature rise of the second bearing 11B is predicted in the operating state, and the bearing gap of the second bearing 11B is set large in advance.
  • the second bearing 11B is a product of the same series as the first bearing 11A (the cross-sectional area of the rolling element is the same size) and has a diameter at least one size larger. For example, a part having an inner diameter of 40.6 cm (16 inches) is used as the second bearing 11B with respect to the first bearing 11A having an inner diameter of 35.6 cm (14 inches).
  • the internal gap of the radial bearing before assembly of the second bearing 11B is set to about 90 to 140 ⁇ m
  • a bearing having a size commensurate with the numerical value of this internal gap is selected from the part numbers of commercially available products and used.
  • the bearing used in this embodiment is not a custom-made product, but is preferably selected from parts produced as a general standard product and supplied to the market. That is, it is preferable that the internal clearance of the radial bearing is selected from the numerical range recommended as the catalog value.
  • Table 1 shows examples of bearing dimensional values that are generally available on the market.
  • the rolling elements 10 of the first bearing 11A and the second bearing 11B and the coil end portion of the coil 2Z that is, the first coil end portion 2ZA and the second The coil end portion 2ZB is arranged in the flow path 15 in which the liquid medium is housed.
  • the gap 7 is a first axial flow path through which the liquid medium flows in the axial direction
  • the first bearing 11A is arranged on the liquid medium inlet 14A side of the first axial flow path
  • the second bearing 11B is the first. It is arranged on the liquid medium outlet 14B side of the axial flow path. Further, the inner diameter of the second bearing 11B is larger than the inner diameter of the first bearing 11A.
  • the rotor core 4X is fixed, the rotor housing 4W in which the flow path 15 through which the liquid medium flows is formed, the stator 2 arranged on the inner peripheral side of the rotor core 4X, and the rotor housing 4W.
  • An outer rotor type in-wheel motor 51 including a first oil seal 20A and a second oil seal 20B arranged between the stator 2 and the stator 2.
  • the rotor housing 4W has an outer peripheral portion 4C arranged on the outer peripheral side of the stator 2, an outer inner peripheral portion 4SA and an inner inner peripheral portion 4SB arranged on the inner peripheral side of the stator 2, and an outer peripheral portion 4C and an outer inner circumference. It includes an outer connecting portion 4A for connecting the peripheral portion 4SA, an inner connecting portion 4B for connecting the outer peripheral portion 4C and the inner inner peripheral portion 4SB. Further, the first oil seal 20A includes a first fixing portion 20AT fixed to the inner peripheral surface (first seal mounting portion 2AK) of the stator 2 and a first contact portion 20AS which is in sliding contact with the outer inner peripheral portion 4SA. Have.
  • the second oil seal 20B includes a second fixing portion 20BT fixed to the inner peripheral surface (second seal mounting portion 2BK) of the stator 2, a second contact portion 20BS which is in sliding contact with the inner inner peripheral portion 4SB, and the second contact portion 20BS. Has.
  • the internal pressure of the liquid medium near the first oil seal 20A and the second oil seal 20B decreases, so that the first oil seal 20A and the second oil seal 20B slide. Resistance is relaxed and life is extended. Further, since the foreign matter is separated from the vicinity of the first oil seal 20A and the second oil seal 20B and flowed to the outer peripheral side by the centrifugal force, the occurrence of the seal failure due to the foreign matter can be suppressed.
  • the in-wheel motor 51 of the present embodiment has a bearing 11 between the outer peripheral portion 4C of the rotor housing 4W and the stator 2, and the bearing 11 is sealed by the first oil seal 20A and the second oil seal 20B. It is installed in the flow path 15 provided. Further, the diameter of the bearing 11 is larger than the diameter of the first fixing portion 20AT of the first oil seal 20A.
  • the first contact portion 20AS of the first oil seal 20A becomes the innermost circumference of the flow path, so that the wear debris of the bearing 11 is blown outward by centrifugal force and is less likely to be mixed into the first contact portion 20AS.
  • the life of the first oil seal 20A can be extended. Further, by making the oil seal diameter relatively small, the sliding peripheral speed can be lowered and the rotational resistance of the first oil seal 20A can be reduced.
  • the annular flow path 18 is provided on the inner peripheral side of the stator core 2X, thereby improving the overall cooling efficiency.
  • flat and thin bearings having different diameters are used for the first bearing 11A and the second bearing 11B.
  • the first bearing 11A has a larger diameter than the first oil seal 20A
  • the second bearing 11B has a larger diameter than the second oil seal 20B.
  • 13 and 16 show partial cross-sectional perspective views of the in-wheel motor 52 according to the present embodiment.
  • the liquid medium flow 15R and the annular flow path 18 generate heat generated inside by flowing exclusively in the axial direction from the liquid medium inlet 14A to which the externally cooled liquid medium is supplied toward the liquid medium outlet 14B. It has the function of absorbing and exhausting heat.
  • the liquid medium contained in the outer inner flow path 15A and the inner inner flow path 15B has a function of lowering the internal pressure in the vicinity of the oil seal as the rotor 4 rotates. Further, the liquid medium has a function of lubricating and cooling the first oil seal 20A and the second oil seal 20B.
  • FIGS. 10 to 12 show the structure of the annular flow path 18 in this embodiment.
  • an annular flow path 18 surrounded by a cylindrical space between the inner peripheral side surface of the stator core 2X and the outer peripheral side surface of the main body 2C is provided. ..
  • the liquid medium flow 15R is arranged in the gap 7 on the outer peripheral side of the stator core 2X, and the annular flow path 18 is arranged below the stator core 2X.
  • the annular flow path 18 is composed of circumferential passages 17a, 17b, 17c arranged in three stages in the axial direction, and oblique traffic passages 17ab, 17bc connecting the circumferential passages in series. Will be done.
  • the annular flow path 18 is formed by dividing the flow path by a plurality of walls having heights in the radial direction on the surface of the main body 2C.
  • the upstream end of the first-stage circumferential passage 17a of the annular passage 18 is connected to the annular passage inlet 16A, and the downstream end is connected to the oblique traffic passage 17ab.
  • the oblique traffic passage 17ab is continuously connected to the middle-stage circumferential passage 17b, the second-stage oblique traffic passage 17bc, the third-stage circumferential passage 17c, and the annular flow path exit 16B.
  • the annular flow path 18 in the present embodiment includes one or more oblique traffic paths 17ab and 17bc on the way from the annular flow path inlet 16A to the annular flow path outlet 16B.
  • the passage cross-sectional area in the traveling direction of each passage is set to be substantially the same in order to reduce the passage loss. Further, in order to reduce the passage resistance of the liquid medium, it is preferable that the intersection angle between the oblique traffic path and the circumferential passage is not so large.
  • the liquid medium travels through the annular flow path 18 having such a structure, the liquid medium flows a plurality of times in the circumferential direction while being in contact with the inner surface of the stator core 2X. Therefore, when the liquid medium passes through the annular flow path 18, the contact time with the stator core 2X becomes longer, and it becomes easier to absorb heat in the vicinity of the stator core 2X.
  • the heat absorption efficiency of the liquid medium passing through the annular flow path 18 is increased, the difference between the temperature of the liquid medium near the liquid medium inlet 14A and the temperature of the liquid medium near the liquid medium outlet 14B becomes larger.
  • the annular flow path 18 corresponds to a second axial flow path that can coexist with the liquid medium flow 15R, which is the first axial flow path passing through the gap 7.
  • the passage route of the liquid medium in this embodiment is as follows.
  • the pipe connected to the heat exchanger (not shown) is attached to the external intake 13A located on the inner peripheral side of the main body 2C.
  • the liquid medium is supplied to the inside of the in-wheel motor 52 from the external intake 13A.
  • the liquid medium enters the space immediately below the first coil end portion 2ZA of the flow path 15 from the liquid medium inlet 14A.
  • the liquid medium at the time of being supplied to the liquid medium inlet 14A has a higher pressure than the other parts of the flow path 15.
  • the liquid medium supplied to the inside of the in-wheel motor 52 is roughly divided into two flow paths.
  • the first flow path is the liquid medium flow 15R as in the case of the first embodiment.
  • the liquid medium enters the first coil end space 9A from the liquid medium inlet 14A near the first coil end portion 2ZA. Since the outermost peripheral side of the first coil end space 9A is directly connected to the gap 7, the liquid medium flows in the circumferential direction in the first coil end space 9A and crosses the gap 7 which is a cylindrical space. It flows toward the coil end portion 2ZB.
  • FIGS. 11 and 12 schematically show the structure near the first coil end space 9A and the flow of the liquid medium.
  • the liquid medium enters the first coil end space 9A from the vicinity of the first coil end portion 2ZA, and is further shunted in two directions on the left and right with respect to the circumferential direction.
  • One of them is the first rotating flow 9F1 flowing in the first direction in the first coil end space 9A.
  • the other is a second rotating flow 9F2 that flows in the opposite direction through the first coil end space 9A. It shows how the first rotary flow 9F1 and the second rotary flow 9F2, which are shunted near the liquid medium inlet 14A, each half-circle the first coil end space 9A and merge at a position 180 degrees opposite to the liquid medium inlet 14A. ing.
  • a ring road entrance 16A is provided near the confluence.
  • a part of the stator core 2X of the annular flow path inlet 16A is processed into a concave shape.
  • the first coil end space 9A communicates with the annular flow path 18 on the back side of the stator core 2X. Therefore, the liquid medium can enter the annular flow path 18 from the annular flow path inlet 16A.
  • the first rotating flow 9F1 and the second rotating flow 9F2 make a half turn in the circumferential direction and then merge to form a downward flow 9F3.
  • the downward flow 9F3 becomes an introduction flow 9F4 toward the annular flow path 18 by changing the flow direction from the downward direction to the axial direction at the bottom of the inlet of the annular flow path inlet 16A.
  • FIG. 10 shows the configuration of the liquid medium passage in the annular flow path 18.
  • the liquid medium enters the first-stage circumferential passage 17a, and then enters the oblique traffic route 17ab after about one round. Further, the liquid medium passes through the circumferential passage 17b, the oblique traffic passage 17bc, and the circumferential passage 17c in this order, and reaches the annular passage outlet 16B.
  • the liquid medium becomes a lead-out flow 9F5 from the circumferential flow to the axial direction in the vicinity of the annular flow path outlet 16B.
  • the lead flow 9F5 becomes an upward flow 9F6 inside the annular flow path outlet 16B.
  • the liquid medium enters the second coil end space 9B near the second coil end portion 2ZB.
  • the liquid medium is again shunted in two directions in the second coil end space 9B. It is the same as the first shunt flow in the case of the first coil end space 9A described above, and is shunted into the third rotation flow 9F7 and the fourth rotation flow 9F8 flowing through the second coil end space 9B.
  • a small part of the liquid medium may pass so as to cross the rolling element 10 of the bearing 11 in the axial direction. Further, a part of the liquid medium that crosses the bearing interiors 11AS and 11BS (see FIG. 8) of the bearing 11 may reach the outer internal flow path 15A which is a gap space between the first end bracket 2A and the housing body 4CE. be. Alternatively, the liquid medium may reach the inner internal flow path 15B, which is a gap space between the stator housing 2W and the inner connecting portion 4B.
  • the liquid medium lubricates and cools the oil seal.
  • the rotor 4 of the in-wheel motor 51 rotates, the internal pressure near the oil seal is reduced.
  • the outer inner flow path 15A, the inner inner flow path 15B, the liquid medium flow 15R, and the annular flow path 18 are provided in the gap space between the stator housing 2W and the rotor housing 4W. Has been done.
  • the liquid medium cools and lubricates the target parts, and a large amount of the liquid medium flows in the axial direction, so that the function of exhaust heat is enhanced as a whole.
  • all of the coil 2Z wound around the stator core 2X, the first coil end portion 2ZA, and the second coil end portion 2ZB are covered with the liquid medium.
  • a first coil end flow through which the liquid medium passes through the first coil end space 9A and a second coil end flow through which the liquid medium passes through the second coil end space 9B are provided.
  • an annular flow path 18 through which the liquid medium flows in the circumferential direction and also travels in the axial direction is provided. Therefore, the cooling efficiency of the in-wheel motor 51 is further improved.
  • a liquid medium flow 15R in which the liquid medium flows in the axial direction and an annular flow path 18.
  • the gap 7 of the in-wheel motor 52 is a narrow space between the stator core 2X and the rotor core 4X.
  • the liquid medium passes through this narrow space. Therefore, if the pressure loss is relatively small with respect to the annular flow path 18, the liquid medium does not flow into the annular flow path 18 but flows toward the gap 7.
  • the cooling efficiency of the in-wheel motor as a whole drops. Narrowing the gap 7 also leads to an improvement in torque as an in-wheel motor. Therefore, when the gap 7 is narrowed, the pressure loss in the liquid medium path becomes sufficiently small, and the required torque can be generated.
  • 0.5 mm is an example of the design value of the gap 7.
  • FIG. 13 shows a partially enlarged view of the bearing 11 of the in-wheel motor 51.
  • the first bearing 11A and the second bearing 11B are thin and flat bearings of the same system.
  • the second bearing 11B used has a diameter at least one size larger than that of the first bearing 11A.
  • the first bearing 11A has a first outer ring 10A OR and a first inner ring 10A IR .
  • the space between the first outer ring 10A OR and the first inner ring 10A IR is the bearing inner 11AS.
  • the gap between the first outer ring 10A OR and the first rolling element 10A is 10A GPH .
  • the gap between the first inner ring 10A IR and the first rolling element 10A is 10A GPL .
  • the outer diameter of the first outer ring 10A OR is D 1-1 , and the inner diameter is L 1-2 .
  • the outer diameter of the first inner ring 10AIR is L 1-1 , and the inner diameter is d1.
  • the width of the first outer ring 10A OR is W 1 .
  • the second bearing 11B has a second outer ring 10B OR and a second inner ring 10B IR .
  • the space between the second outer ring 10B OR and the second inner ring 10B IR is the bearing inner 11BS.
  • the gap between the second outer ring 10B OR and the second rolling element 10B is 10B GPH .
  • the gap between the second inner ring 10B IR and the second rolling element 10B is the 10B GPL .
  • the outer diameter of the second outer ring 10B OR is D 2-1 and the inner diameter is L 2-2 .
  • the outer diameter of the second inner ring 10B IR is L 2-1 and the inner diameter is d 2 .
  • the width of the second outer ring 10B OR is W 2.
  • the second bearing 11B is selected from thin flat bearings having a diameter one size larger than that of the first bearing 11A. Similar to the first embodiment described above, in this embodiment as well, the life of the second bearing 11B is extended by using a bearing having a diameter larger than that of the first bearing 11A for the second bearing 11B. Therefore, in the setting of the second bearing 11B, the condition is set so that the operating gap is 0 or more.
  • the in-wheel motor 52 of the present embodiment is provided with the annular flow path 18, so that the internal cooling efficiency is excellent. Further, since the liquid medium inlet 14A and the liquid medium outlet 14B are directly below the first coil end portion 2ZA and the second coil end portion 2ZB, respectively, foreign matter is suppressed from being mixed into the first bearing 11A and the second bearing 11B. be able to.
  • the in-wheel motor 52 of the present embodiment has a first bearing 11A and a second bearing 11B between the outer peripheral portion 4C of the rotor housing 4W and the main body 2C, and the first bearing 11A and the second bearing 11B have the first bearing 11A and the second bearing 11B.
  • the diameter of the first bearing 11A is larger than the diameter of the first fixing portion 20AT of the first oil seal 20A
  • the second bearing The diameter of 11B is larger than the diameter of the second fixing portion 20BT of the second oil seal 20B.
  • the life of the first oil seal 20A and the second oil seal 20B can be extended, and the stable operation and the life of the first bearing 11A and the second bearing 11B can be extended.
  • FIG. 17 shows a partial cross-sectional view of the in-wheel motor 53 according to the third embodiment.
  • the first fixing portion 20AT of the first oil seal 20A is fixed to the stator housing 2W.
  • the flow path 15 including the outer inner flow path 15A is surrounded by the outer peripheral portion 4C, the outer connection portion 4A, and the outer inner peripheral portion 4SA.
  • a protrusion 2CN is provided from the first end bracket 2A toward the outside of the vehicle body in the vicinity of the outer inner peripheral portion 4SA. It is adjacent to the outer inner peripheral portion 4SA in the radial direction through a slight gap.
  • the first end bracket 2A included in the stator housing 2W is provided with the outer inner peripheral portion 4SA and the cylindrical protrusion 2CN adjacent in the radial direction.
  • the outer inner peripheral portion 4SA and the protrusion 2CN form a labyrinth to prevent foreign matter from entering the vicinity of the first contact portion 20AS of the first oil seal 20A.
  • This protrusion 2CN is also continuously provided in the rotation direction of the wheel shaft AX passing through the hub bearing HUB.
  • the entire protrusion 2CN has a hollow cylindrical shape. The smaller the gap between the protrusion 2CN and the outer inner peripheral portion 4SA and the longer the overlap, the greater the effect of suppressing foreign matter from entering from the outside.
  • a protrusion 2CN is provided on the inner peripheral side (position between the outer inner peripheral portion 4SA and the hub bearing HUB) of the outer inner peripheral portion 4SA included in the rotor 4 (housing body 4CE). As a position opposite to this, it may be provided on the slightly outer peripheral side of the outer inner peripheral portion 4SA. Further, protrusions 2CN may be provided on both the inner peripheral side and the outer peripheral side so as to sandwich the outer inner peripheral portion 4SA from both sides.
  • FIG. 18 shows a partial cross-sectional view of the in-wheel motor 54 according to the fourth embodiment.
  • the configuration of the first oil seal 20A and the like in this embodiment is the same as that in the third embodiment described above.
  • a cylindrical recess 2CV is provided on the surface of the first end bracket 2A facing the outer inner peripheral portion 4SA toward the outside of the vehicle body. A part of the tip of the outer inner peripheral portion 4SA is arranged so as to enter the recess 2CV.
  • the first end bracket 2A included in the stator housing 2W is provided with an outer inner peripheral portion 4SA and a cylindrical recess 2CV adjacent in the radial direction.
  • the outer inner peripheral portion 4SA and the concave portion 2CV form a labyrinth to prevent foreign matter from entering the vicinity of the first contact portion 20AS of the first oil seal 20A.
  • the recess 2CV Since the recess 2CV is continuously provided in the rotation direction, it has the form of a circular groove as a whole. The smaller the gap between the recess 2CV and the outer inner peripheral portion 4SA and the longer the overlap, the greater the effect of suppressing foreign matter from entering from the outside.
  • FIG. 19 shows a partial cross-sectional perspective view of the in-wheel motor 55 of the present embodiment.
  • the liquid medium inlet 14A is arranged in the flow path 15 between the first oil seal 20A and the first bearing 11A. Further, the liquid medium outlet 14B is arranged in the flow path 15 between the second oil seal 20B and the second bearing 11B.
  • the liquid medium always passes through the inside of the first bearing 11A and the second bearing 11B by this configuration. Further, the liquid medium under pressure flows into the outer inner flow path 15A and the inner inner flow path 15B. Therefore, the cooling efficiency and the lubrication efficiency of the first bearing 11A and the second bearing 11B are improved, respectively.
  • FIG. 20 shows a partial cross-sectional perspective view of the in-wheel motor 56 according to the present embodiment.
  • the diameter of the second oil seal 20B on the liquid medium outlet 14B side is larger than the diameter of the first oil seal 20A on the liquid medium inlet 14A side. Therefore, the second oil seal 20B is attached to the second seal attachment portion 2CK of the main body 2C.
  • the in-wheel motor 56 of the present embodiment by adopting this configuration, the wiring to be connected to the inside of the in-wheel motor 56, the drawing of the cooling pipe (hose), etc., and the stator 2 are fixed to the frame of the wheel 100. As a result, the work of assembling, adjusting, inspecting, and maintaining the in-wheel motor 56 becomes easy.
  • the diameter of the second oil seal 20B is, for example, 10 to 25 cm, preferably 10. It can be set in a range of about 20 cm.
  • the first oil seal 20A or the second oil seal 20B is arranged at a position where it overlaps with the bearing 11 when viewed from the radial direction of the in-wheel motor 51. At least, it is preferable that the first bearing 11A and the first oil seal 20A overlap each other.
  • the shaft length of the motor can be shortened by arranging the bearing 11 of the in-wheel motor 51 and the first oil seal 20A or the second oil seal 20B at the same position in the axial direction.
  • the first oil seal 20A on the liquid medium inlet 14A side and the second oil seal 20B on the liquid medium outlet 14B side have a low pressure resistance type according to the pressure drop due to the pressure loss inside the in-wheel motor. It is preferable to select.
  • the withstand pressure of the second oil seal 20B lower than the withstand pressure of the first oil seal 20A. Since a low pressure resistant type oil seal is used for the second oil seal 20B, the binding force (pressing force) of the rotary contact portion is set to be weak, and the rotation of the second oil seal 20B in the second contact portion 20BS. The resistance becomes smaller and the life of the second oil seal 20B becomes longer.
  • the pressure on the outer peripheral side of the flow path 15 is relatively higher than that on the inner peripheral side. It is preferable because it is easy to discharge from the outlet 14B.
  • the present invention is not limited to these examples, and further modifications can be considered.
  • the position of the oil seal can be changed in the space between the inner peripheral side of the first bearing 11A and the wheel shaft AX in consideration of the relationship with other members.
  • the number of laps of the annular flow path 18 can be changed, and the positions of the liquid medium inlet 14A and the liquid medium outlet 14B can be changed in relation to the improvement of cooling efficiency, the component size, the reduction of the internal volume, and the like. It can be freely combined and configured. Various embodiments can be considered other than using the above-described embodiment and the illustrated parts.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Arrangement Or Mounting Of Propulsion Units For Vehicles (AREA)
  • Motor Or Generator Frames (AREA)
PCT/JP2021/043553 2021-01-15 2021-11-29 回転電機及び車両 WO2022153689A1 (ja)

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Cited By (1)

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Publication number Priority date Publication date Assignee Title
US20220077731A1 (en) * 2019-01-31 2022-03-10 Hitachi Astemo, Ltd. Wheel drive device and electric vehicle provided with the same

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR102803297B1 (ko) * 2022-11-02 2025-05-07 에이치엘만도 주식회사 인 휠 모터 및 인 휠 모터의 조립 방법

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JP2010041853A (ja) * 2008-08-06 2010-02-18 Mitsuba Corp 電動モータ
JP2014075879A (ja) * 2012-10-03 2014-04-24 Sim-Drive Co Ltd アウターロータ式インホイールモータ
CN110289720A (zh) * 2019-05-27 2019-09-27 浙江万安科技股份有限公司 轮毂电机转子和定子的端面密封结构

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Publication number Priority date Publication date Assignee Title
JP2010041853A (ja) * 2008-08-06 2010-02-18 Mitsuba Corp 電動モータ
JP2014075879A (ja) * 2012-10-03 2014-04-24 Sim-Drive Co Ltd アウターロータ式インホイールモータ
CN110289720A (zh) * 2019-05-27 2019-09-27 浙江万安科技股份有限公司 轮毂电机转子和定子的端面密封结构

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20220077731A1 (en) * 2019-01-31 2022-03-10 Hitachi Astemo, Ltd. Wheel drive device and electric vehicle provided with the same
US11949288B2 (en) * 2019-01-31 2024-04-02 Hitachi Astemo, Ltd. Wheel drive device and electric vehicle provided with the same

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