JP6406913B2 - In-wheel motor cooling structure - Google Patents

Description

  The present invention relates to a cooling structure for an in-wheel motor provided adjacent to a wheel of an electric vehicle such as an electric vehicle, and more particularly to a cooling structure with improved cooling capacity by a simple configuration.

In the case of an electric vehicle using an electric motor as a driving power source, it is important to perform appropriate cooling in order to maintain the performance by preventing deterioration or failure of a built-in permanent magnet or device.
For example, Patent Document 1 describes cooling oil for motor lubrication using a heat pipe as a related art relating to cooling of a drive motor or the like of an electric vehicle.
Further, Patent Document 2 describes that a cooling fan that blows air to the in-wheel motor is provided on the brake disk.
Patent Document 3 describes that the exhaust from the cooling air flow path for cooling the inside of the in-wheel motor is discharged toward the inner diameter side of the ventilation type brake disc rotor.

JP 2010-148272 A JP 2006-57732 A JP 2005-168120 A

When the motor for driving an electric vehicle is an in-wheel motor disposed in the wheel house adjacent to the wheel, the motor temperature is increased by heat received from the friction brake during braking in addition to the heat generated by the motor itself. Tends to rise.
In the case of such an in-wheel motor, it is necessary to arrange all the components in a limited space in the wheel house that accommodates the wheel, and since reduction of unsprung weight is also required, It is difficult to arrange a cooling device such as a radiator or a cooler outside the in-wheel motor.
Conventionally, it has been proposed to increase the heat radiation area by forming cooling fins etc. in the housing (housing) of the in-wheel motor, but the strength of the in-wheel motor housing is important because input from the wheel is loaded Therefore, the outer wall is inevitably thick, and it is difficult to ensure sufficient cooling performance.
It is also possible to provide a cooling device that allows the refrigerant to flow. However, since the degree of freedom in setting the refrigerant conveyance path is low and there is not enough room, the cooling device becomes complicated and conveyance due to an increase in pressure loss. The increase in the size of the apparatus, the processing cost of the parts, etc. are problems.
In view of the above-described problems, an object of the present invention is to provide a cooling structure for an in-wheel motor having an improved cooling capacity with a simple configuration.

The present invention solves the above-described problems by the following means.
According to a first aspect of the present invention, there is provided an in-wheel motor configured by housing a stator and a rotor in a housing disposed adjacent to a wheel and connecting a hub to which the wheel is attached to an output shaft fixed to the rotor. A ventilation brake disk attached to the hub and formed with an air flow path communicating from the inner diameter side to the outer diameter side; an end face of the housing in the vehicle width direction; and the ventilation brake disk; Air guide means for sucking air from the space between the air flow passages and introducing it into the end portion on the inner diameter side of the air flow path, wherein the housing is filled with a refrigerant and one end portion is A refrigerant flow path extending along a region of the housing where lubricating oil is stored, and having the other end portion extending along an end surface on the outer side in the vehicle width direction of the housing. A cooling structure for in-wheel motor.
According to this, when the vehicle travels (when the wheel rotates), the air guide means sucks air from the space between the housing and the ventilated brake disc, so that almost the entire surface on the brake disc side of the housing. Accordingly, cooling air flowing from the outer diameter side to the inner diameter side can be formed, and the in-wheel motor can be effectively cooled without using dedicated power for cooling.
Moreover, since the air heated by the brake disc can be prevented from flowing to the housing side, the amount of heat received from the brake disc to the in-wheel motor can be reduced, and the temperature of the in-wheel motor can be further reduced.
Note that the air sucked by the air guiding means is transported inside the ventilated brake disk by the pressure difference between the outlet side of the air guiding means and the atmospheric pressure, and the centrifugal force due to the rotation of the ventilated brake disk. Is exhausted .
Furthermore, the heat of the oil, which has become high temperature due to the heat of each part of the in-wheel motor, can be carried to the outer end surface side of the housing in the vehicle width direction, and can be effectively cooled by the cooling air formed by the air guiding means.

According to a second aspect of the present invention, the air guide means is a disk-shaped device in which a plurality of air scoops that are fixed to the hub and open toward the space portion toward the front side in the rotational direction when the vehicle moves forward are distributed in the circumferential direction. The in-wheel motor cooling structure according to claim 1, further comprising an air guide plate.
According to this, the effect mentioned above can be acquired reliably with a simple configuration.
Such a wind guide plate can be produced easily, inexpensively, and lightly by, for example, sheet metal pressing.

According to a third aspect of the present invention, the air guide means is disposed so as to form a space between the hub, and is fixed to the hub, and the space portion is directed forward in the rotational direction when the vehicle moves forward. A rectifying plate having an air scoop open to the side, wherein the hub and the rectifying plate are configured to rotate about a rotation shaft, and the space between the rectification plate and the hub is configured to rotate the rotation shaft. 3. The cooling structure for an in-wheel motor according to claim 1 , wherein the cooling structure is overlapped with the air flow path in a direction.

  As described above, according to the present invention, it is possible to provide a cooling structure for an in-wheel motor with improved cooling capacity with a simple configuration.

It is sectional drawing of the in-wheel motor periphery part in Example 1 of the cooling structure of the in-wheel motor to which this invention is applied. It is a cross-sectional perspective view of the periphery of the in-wheel motor in the first embodiment. It is the III-III part arrow directional view of FIG. It is the external appearance perspective view which looked at the hub and rectifier plate in Example 1 from the in-wheel motor side. FIG. 3 is an enlarged cross-sectional perspective view of the periphery of the current plate in the cooling structure for the in-wheel motor according to the first embodiment. It is a cross-sectional perspective view of the in-wheel motor in Example 2 of the cooling structure of the in-wheel motor to which this invention is applied.

Embodiment 1 of the cooling structure for an in-wheel motor to which the present invention is applied will be described below.
FIG. 1 is a cross-sectional view of the periphery of an in-wheel motor in the first embodiment, and is a view cut along a plane including a rotation center axis and along a vertical direction.
FIG. 2 is a cross-sectional perspective view of the periphery of the in-wheel motor.
FIG. 3 is a view taken along the line III-III in FIG.
FIG. 4 is an external perspective view of the hub and the current plate in the first embodiment when viewed from the in-wheel motor side.

The in-wheel motor 1 according to the first embodiment is a drive motor that is disposed adjacent to a wheel of an electric vehicle such as an electric vehicle or an engine electric hybrid vehicle, and at least a part thereof is attached with a bead portion of a tire. It is accommodated on the inner diameter side of the rim.
The in-wheel motor 1 is, for example, a permanent magnet (PM) type three-phase AC induction motor that is used as a power source for driving a vehicle (a driving force generation source) and also functions as a regenerative generator during braking. Is.

The in-wheel motor 1 includes a stator 10, a rotor 20, an output shaft 30, a housing 100, and the like.
The stator 10 has a coil around which a coil winding is wound around a core made of a magnetic material.
The stator 10 is formed in an annular shape, and the coils are arranged in the circumferential direction, for example, divided into a U phase, a V phase, and a W phase.
AC power supplied from an inverter (not shown) is supplied to the coil windings of each phase, and a rotating magnetic field is formed around the stator 10.

The rotor 20 is formed by embedding a plurality of permanent magnets inside a magnetic iron plate formed in a disk shape.
The rotor 20 is supported by the stator 10 so as to be rotatable around a predetermined rotation center axis.
The rotor 20 is inserted into the stator 10 and is rotationally driven by a magnetic field generated by a coil.

The output shaft 30 is a rotation shaft that transmits the rotation output of the rotor 20 to the hub 210.
The output shaft 30 is held by a bearing (not shown) so that the rotor 20 is fixed to the outer peripheral surface portion of the intermediate portion and is rotatable about the central axis with respect to the housing 100.
An end of the output shaft 30 on the outer side (wheel side) in the vehicle width direction is provided so as to protrude from the housing 100, and the hub 210 is fastened.

The housing 100 is a case (housing) of the in-wheel motor 1 in which the stator 10, the rotor 20, and the like are accommodated.
The housing 100 includes a main body part 110, an inner cover part 120, an outer cover part 130, and the like.
The main body part 110, the inner cover part 120, and the outer cover part 130 are formed by, for example, casting a metal such as an aluminum alloy and then performing predetermined machining on necessary portions.

  The main body 110 is formed in a substantially cylindrical shape arranged substantially parallel to the axle, and the stator 10 is fixed to the inner peripheral surface portion.

The inner cover part 120 is a lid-like member that closes the opening of the main body part 110 on the inner side in the vehicle width direction (vehicle center side).
The inner cover part 120 sucks up the lubricating oil stored in the lower part (oil pan part P) inside the housing 100 and supplies it to the oil path 121 to supply lubricating oil to each part of the in-wheel motor 1. An oil pump 122 or the like is provided.

The outer cover part 130 is a lid-like member that closes the opening of the main body part 110 on the outer side in the vehicle width direction (hub 210 side).
An opening 131 through which the output shaft 30 passes is formed at the center of the outer cover portion 130.

An oil pan portion P that protrudes downward and stores lubricating oil is formed at the lower portion of the housing 100.
Lubricating oil that lubricates and cools each part of the in-wheel motor 1 is stored in a region below the oil level L illustrated by a broken line in FIG.

The housing 100 further includes a heat pipe 140.
The heat pipe 140 is a tubular member sealed with a refrigerant sealed therein.
The refrigerant convects and circulates inside the heat pipe 140 to transmit the heat of the lubricating oil from the inside of the housing 100 to the outer surface side of the outer cover portion 130.
The heat pipe 140 is formed by integrally forming an oil insertion portion 141 and a cooled portion 142.

The in-oil insertion portion 141 is a straight portion that is inserted substantially along the rotational axis direction of the in-wheel motor 1 from an opening provided near the lower end portion of the outer cover portion 130.
Substantially all of the in-oil insertion portion 141 disposed inside the housing 100 is provided in a region below the oil level L, and is disposed in the lubricating oil.
The oil inner insertion portion 141 is held at its end on the outer cover portion 130 side by a cylindrical bracket 141 a that is press-fitted into the opening of the outer cover portion 130.
The oil insertion portion 141 is press-fitted into the inner diameter side of the bracket 141 a, and the outer peripheral surface of the bracket 141 a is press-fitted into an opening formed in the outer cover portion 130.
A flange portion projecting to the outer diameter side is formed at an end portion of the bracket 141a on the brake disc 220 side.
Further, an oil seal (not shown) that seals the lubricating oil between the bracket 141a and the oil insertion portion 141 is provided on the inner peripheral surface portion of the bracket 141a.

The cooled portion 142 is formed continuously with the end portion on the outer cover portion 130 side of the in-oil insertion portion 141 and is disposed along the outer surface of the outer cover portion 130 (the surface portion on the brake disc 220 side). Yes.
As shown in FIG. 3, the cooled portion 142 extends upward along a groove formed on the outer surface of the outer cover portion 130, and the main portion is substantially concentric with the central axis of the in-wheel motor 1. It is arranged in an arc shape.
In particular, when a plurality of (for example, four in the first embodiment) heat pipes 140 are arranged as in the first embodiment, the arc-shaped portions are arranged concentrically.
The upper end portion 142 of the cooled portion 142 reaches a region above the output shaft 30.

A hub 210 is fastened to the output shaft 30.
A brake disc 220 and a current plate 230 are fastened to the hub 210.
The hub 210 is a member in which a wheel rim center portion (disk portion) (not shown) is fastened by a hub bolt and a wheel nut.
The hub 210 includes a disk portion 211, a cylindrical portion 212, and the like that are integrally formed of, for example, steel.
The disk portion 211 is formed substantially concentrically with the output shaft 30.
An opening 211 a into which the end of the output shaft 30 is inserted and fastened by a nut N is formed at the center of the disk portion 211.
The cylindrical portion 212 is formed in a cylindrical shape concentric with the output shaft 30, and is formed so as to protrude from the center portion of the disk portion 211 (the peripheral portion of the opening 211 a) to the inside of the housing 100.
The end of the output shaft 30 on the hub 210 side is inserted and fixed to the inner diameter side of the cylindrical portion 212.

A protrusion 213 is formed on the surface of the disk portion 211 on the housing 100 side.
The ridge 213 is formed so as to protrude from the surface portion of the disk portion 211 on the housing 100 side, and extends along the radial direction of the disk portion 211.
For example, five ridges 213 are arranged radially at equal intervals in the circumferential direction of the disk portion 211.
The ridge 213 is a portion to be a base portion to which the rectifying plate 230 is attached.

The brake disc 220 constitutes a hydraulic service brake for the vehicle in cooperation with a brake caliper (not shown).
The brake disk 220 is formed by integrally forming a sandwiched portion 221, a fastening portion 222, and the like, for example, from cast iron.
The brake disk 220 is a ventilated disk rotor in which an air flow path 221 a that communicates from the inner diameter side to the outer diameter side is formed inside the sandwiched portion 221.

The to-be-clamped part 221 converts a kinetic energy into a thermal energy and generates a braking force by generating frictional force by being sandwiched by a brake pad provided in the brake caliper.
The sandwiched portion 221 is formed in a disk shape having an opening at the center.
The disc portion 211 of the hub 210 is inserted into the central opening of the sandwiched portion 221.

An air flow path 221a extending from the inner peripheral edge to the outer peripheral edge of the sandwiched portion 221 is formed at an intermediate portion in the axial direction of the sandwiched portion 221.
The air flow path 221a is formed so as to penetrate through the inside of the sandwiched portion 221 almost along the radial direction, and a plurality of the air flow paths 221a are radially arranged and distributed in the circumferential direction.
The fastening portion 222 is a portion that is provided at the center portion of the sandwiched portion 221 and is fastened to the disc portion 211 of the hub 210 by the bolt B.
The fastening part 222 is arranged with a stepped offset to the outside in the vehicle width direction with respect to the sandwiched part 221, and as a result, the sandwiched part 221 extends in a hook shape around the fastening part 222. It is formed in a hat shape.

As shown in FIG. 4, the rectifying plate 230 is a disk-shaped member attached to the housing 100 side of the disk portion 211 of the hub 210.
The rectifying plate 230 is fixed to the hub 210 by, for example, mechanical fastening means such as screws, press-fitting, welding, or the like, and rotates together with the hub 210 and the brake disc 220 according to the rotation of the wheel.
The rectifying plate 230 is disposed at a predetermined interval in the axial direction from the disk portion 211, and a space portion through which cooling air can pass is formed between them.

The rectifying plate 230 is integrally formed by pressing a sheet metal member such as a steel plate.
The rectifying plate 230 includes an air scoop 231, a protrusion engaging portion 232, and the like.
The air scoop 231 takes in the air on the housing 100 side of the rectifying plate 230 and introduces it into the space between the rectifying plate 230 and the disk portion 211 of the hub 210 when the rectifying plate 230 rotates.
This space portion is arranged so that the position in the rotation axis direction substantially overlaps with the air flow path 221a of the brake disc 220.
The air scoop 231 is formed, for example, by opening a part of the rectifying plate 230 by press working so as to open to the front side in the rotational direction of the rectifying plate 230 when the vehicle moves forward. The air scoops 231 are distributed in the circumferential direction of the rectifying plate 230 and are provided, for example, at five locations.

The ridge engaging portion 232 is a portion that positions the rectifying plate 230 when the tip of the ridge 213 of the hub 210 is fitted.
The protrusion engaging portion 232 is configured by projecting a part of the rectifying plate 230 in a blister shape so that the housing 100 side is convex.
The protrusion engaging portions 232 are arranged radially at, for example, five places on the circumference of the rectifying plate 230 so as to match the shape and arrangement of the protrusions 213.
Around the circumference of the current plate 230, the air scoops 231 and the protrusion engaging portions 232 are alternately arranged.

Hereinafter, the effect of the first embodiment will be described.
FIG. 5 is an enlarged cross-sectional perspective view of the periphery of the current plate 230 in the cooling structure for the in-wheel motor of the first embodiment.
In FIG. 5, the airflow (cooling air W) generated when the vehicle travels (during forward rotation of the wheel) is illustrated by arrows.
When the vehicle travels, the current plate 230 rotates counterclockwise in FIG. 5, so that the air scoop 231 is in the space between the sandwiched surface 221 of the brake disc 220 and the outer cover portion 130 of the housing 100. Air is taken in and sucked into the space between the current plate 230 and the disk portion 211 of the hub 210.

Such air intake is performed from the entire circumference of the rectifying plate 230 as it rotates, so that the cooling air W flowing from the outer diameter side to the inner diameter side along the surface of the outer cover portion 130 is substantially all. Occurs over the lap.
The cooling air W directly cools the outer cover portion 130 and cools the cooled portion 142 of the heat pipe 140, thereby lowering the refrigerant temperature in the heat pipe 140, and thereby the oil pan portion P in the housing 100. The lubricating oil stored in is cooled.

  The air taken in between the rectifying plate 230 and the disk portion 211 is introduced into the air flow path 221a by the differential pressure between the pressure in this region and the atmospheric pressure and the centrifugal force generated by the rotation of the brake disc 220. The air is exhausted to the outer diameter side of the brake disc 220 through the inside.

As described above, according to the first embodiment, the following effects can be obtained.
(1) When the vehicle travels (when the wheel rotates), the rectifying plate 230 draws air from the space between the housing 100 and the brake disc 220, so that the housing 100 has almost the entire surface on the brake disc 220 side. The cooling air W which flows along can be formed, and the in-wheel motor 1 can be cooled effectively without using a dedicated power for cooling.
Further, the amount of heat received from the brake disc 220 to the in-wheel motor 1 can also be reduced, and the temperature of the in-wheel motor 1 can be further reduced.
(2) By using the current plate 230 in which the air scoop 231 is formed by pressing a sheet metal, the above-described effects can be reliably obtained with a simple configuration.
(3) By providing the heat pipe 140, the heat of the lubricating oil that has become high temperature due to the heat of each part of the in-wheel motor 1 is carried to the outer cover part 130 side of the housing 100, and the cooling air W formed by the rectifying plate 230. Can be cooled effectively.

Next, a second embodiment of the cooling structure for an in-wheel motor to which the present invention is applied will be described.
In each of the embodiments described below, portions that are substantially the same as those of the previous embodiment are denoted by the same reference numerals, description thereof is omitted, and differences are mainly described.

FIG. 6 is a partial cross-sectional perspective view of the in-wheel motor according to the second embodiment.
In the in-wheel motor 1 of the second embodiment, instead of the heat pipe 140 in the first embodiment, a cooling oil passage 151 is provided inside the lower surface portion of the main body 110 of the housing 100 and inside the outer cover portion 130. , 152 are formed.
The oil passage 151 is disposed substantially along the rotational axis direction of the in-wheel motor 1, and the end on the outer cover portion 130 side is open.
The oil passage 152 is formed so as to communicate with the oil passage 151 and extends along a surface portion of the outer cover portion 130 that faces the brake disc 220.
The oil passages 151 and 152 are sealed by a plug (not shown) after the same refrigerant as the heat pipe 140 is sealed.

  According to the second embodiment described above, the number of components can be reduced in addition to the effects substantially similar to the effects of the first embodiment.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications and changes are possible, and these are also within the technical scope of the present invention.
(1) The shape, structure, material, manufacturing method, quantity, arrangement, and the like of the in-wheel motor and its peripheral parts are not limited to the configuration of the above-described embodiment, and can be changed as appropriate.
(2) In the embodiment, one end portion of the heat pipe is disposed on the end surface side on the wheel side of the housing, but may be disposed on the end surface side on the opposite wheel side (right side in FIG. 1).
In this case, a cooling fan may be generated by providing a blower fan that is linked to the output shaft of the in-wheel motor adjacent to the end surface on the side opposite to the wheel.

DESCRIPTION OF SYMBOLS 1 In-wheel motor 10 Stator 20 Rotor 30 Output shaft 100 Housing 110 Main body part 120 Inner cover part 121 Oil path 122 Oil pump 130 Outer cover part 131 Opening 140 Heat pipe 141 Insertion part in oil 141a Bracket 142 Cooled part 151 Oil path 152 Oil passage 210 Hub 211 Disk part
211a Opening 212 Cylindrical part 213 Projection 220 Brake disk 221 Clamped part
221a Air flow path 222 Fastening portion 230 Rectifying plate 231 Air scoop 232 Projection engagement portion P Oil pan portion W Cooling air L Oil level

Claims (3)

A cooling structure for an in-wheel motor configured by housing a stator and a rotor in a housing disposed adjacent to a wheel and connecting a hub to which the wheel is attached to an output shaft fixed to the rotor;
A ventilated brake disc attached to the hub and formed with an air flow path communicating from the inner diameter side to the outer diameter side;
An air guide means for sucking air from a space portion between the end surface of the housing in the vehicle width direction outside and the ventilated brake disc and introducing the air into an end portion on the inner diameter side of the air flow path;
The housing is filled with a refrigerant, and one end portion extends along a region where the lubricating oil in the housing is stored, and the other end portion is an end surface on the outer side in the vehicle width direction of the housing. A cooling structure for an in-wheel motor, characterized by having a refrigerant flow path extending along. The air guide means includes a disk-shaped air guide plate in which a plurality of air scoops that are fixed to the hub and open toward the space portion toward the front side in the rotational direction when the vehicle moves forward are distributed in the circumferential direction. The cooling structure for an in-wheel motor according to claim 1 . The air guide means includes an air scoop that is disposed so as to form a space between the air guide and the hub, and that is fixed to the hub and opens toward the space portion toward the front side in the rotational direction when the vehicle moves forward. With a baffle,
The hub and the rectifying plate are configured to rotate around a rotation axis,
3. The in-wheel motor according to claim 1, wherein the space between the rectifying plate and the hub is disposed so as to overlap the air flow path in the rotation axis direction. Cooling structure.

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