JP6055755B2 - Wheel drive mechanism cooling device - Google Patents

Description

  The present invention relates to an apparatus for cooling a mechanism for driving a wheel, and more particularly to an apparatus for cooling an electric motor (in-wheel motor) that is provided inside a wheel of a vehicle drive wheel and rotationally drives the wheel.

In recent years, an in-wheel motor provided inside the wheel of a vehicle drive wheel has been developed. In a vehicle equipped with this in-wheel motor, the configuration of a power transmission system such as a drive shaft and a differential gear can be omitted, and space saving on the vehicle body side can be achieved.
On the other hand, since the in-wheel motor generates heat during high load output or continuous operation, a technology for cooling the in-wheel motor has been developed.

  For example, in Patent Document 1, heat generated by an in-wheel motor is received through a wheel wall surface. When this heat is received, an electromotive force is generated, and an electromotive force generated by the thermoelectric element is directed toward the in-wheel motor. A cooling device having a cooling blower for blowing air is shown. In this cooling device, a thermoelectric element generates an electromotive force according to a temperature difference between the wheel wall surface and the outside air, and an electromotive cooling blower arranged in parallel in the axial direction with respect to the in-wheel motor is operated by this electromotive force. Yes. Thereby, it is supposed that a cooling blower can be operated with the electromotive force according to the calorie | heat amount of a wheel wall surface, and an in-wheel motor can be cooled.

Japanese Patent Application Laid-Open No. 06-144021

  However, since various things such as a brake device and a suspension device as well as a wheel are provided around the in-wheel motor, it is difficult to secure a space, and layout restrictions are severe. For this reason, when the cooling blower is arranged in the axial direction in parallel with the in-wheel motor as in the technique disclosed in Patent Document 1, it may be difficult to cope with layout restrictions. Furthermore, providing a cooling blower in addition to the in-wheel motor may increase the cost.

  In addition, as in the technique disclosed in Patent Document 1, in the case of utilizing the temperature difference between the wheel wall surface that has received heat generated by the in-wheel motor and the outside air, the in-wheel motor is continuously operated or the radiant heat of the brake device is generated. When the ambient temperature of the in-wheel motor or the wheel rises, the temperature difference becomes small, and there is a possibility that the in-wheel motor cannot be sufficiently cooled.

One of the objects of the present invention has been devised in view of the above-described problems, and is a wheel drive mechanism that can appropriately cool an electric motor provided in a wheel with a simple configuration. Is to provide a cooling device.
Note that the present invention is not limited to this purpose, and other effects of the present invention can also be achieved by the functions and effects derived from the respective configurations shown in the embodiments for carrying out the invention which will be described later. Can be positioned as

(1) In order to achieve the above object, a cooling device for a wheel drive mechanism according to the present invention includes a wheel drive mechanism for rotating the wheel by an electric motor provided inside a wheel of a vehicle drive wheel. A substantially cylindrical casing disposed on the outer periphery of the electric motor and having at least one opening formed thereon; a lid member that covers the opening and opens the opening in response to a temperature rise of the electric motor; A coupling portion in which a part of the peripheral edge of the opening and a part of the peripheral edge of the lid member corresponding to the opening are coupled to each other. And a heat-sensitive member whose volume expands, and the lid member opens the opening when the volume of the heat-sensitive member expands . That is, the lid member opens and closes the opening according to the temperature of the electric motor.

( 2 ) Preferably, an aluminum material is used for the heat-sensitive member, and a steel material having a lower thermal expansion coefficient than the aluminum material is used for the lid member and the casing.
( 3 ) Moreover, the said cover member may be comprised with the bimetal.
( 4 ) In the state where the lid member covers the opening, it is preferable that a cylindrical surface be formed on the outer periphery of the casing.

( 5 ) The stator of the electric motor and the casing are integrally joined, and the lid member has a base end coupled to a downstream edge on the downstream side in the rotation direction of the wheel at the periphery of the opening. It is preferable that the portion is separated from the upstream edge portion on the upstream side in the rotation direction of the wheel at the peripheral edge of the opening in accordance with the temperature rise of the electric motor. That is, it is preferable that the front end portion of the lid member is disposed upstream of the base end portion in the rotation direction of the wheel.
( 6 ) It is preferable that a plurality of the openings are provided along the outer peripheral direction of the casing, and a plurality of the lid members are provided corresponding to the openings.

According to the cooling device for a wheel drive mechanism according to the present invention, when the electric motor generates heat, the lid member opens the opening according to the temperature rise, so that the air is exchanged between the inner peripheral side and the outer peripheral side of the casing. (Ventilation) can be performed, and the electric motor provided on the inner peripheral side of the casing can be cooled with air (outside air) on the outer peripheral side of the casing. At this time, if the wheel is rotating, ventilation is promoted by the flow of air accompanying this rotation, and the cooling efficiency of the electric motor can be improved. On the other hand, when the temperature of the electric motor is not increased, the opening is covered (closed) by the lid member, and the electric motor is not cooled. Therefore, the energy loss of the wheel drive mechanism at a low temperature can be suppressed. From these, the electric motor provided in the inside of a wheel can be cooled appropriately.
Further, in order to properly cool the electric motor, it is only necessary to provide a substantially cylindrical casing formed with an opening that is opened and closed by the lid member on the outer periphery of the electric motor. As a result, the degree of freedom in dealing with layout constraints can be improved, and an increase in cost can be suppressed.
In this way, the electric motor provided in the wheel with a simple configuration can be appropriately cooled.

It is sectional drawing which shows typically the whole cooling device of the wheel drive mechanism concerning 1st embodiment of this invention. It is a side view which takes out and shows a casing from the cooling device of the wheel drive mechanism concerning a first embodiment of the present invention. It is a perspective view which expands and shows a part of FIG. It is a perspective view which expands and shows a part of casing when the temperature of an electric motor (IWM) rises in the cooling device of the wheel drive mechanism concerning 1st embodiment of this invention. FIG. 4 shows a portion corresponding to FIG. It is an enlarged view which shows the area | region A of FIG. It is a principal part expanded side view which expands and shows the principal part of the cooling device of the wheel drive mechanism concerning 2nd embodiment of this invention. FIG. 6 shows a portion corresponding to FIG.

Embodiments of the present invention will be described below with reference to the drawings.
A cooling device for a wheel drive mechanism according to the present invention includes an electric motor (“in-wheel motor”, “wheel motor”, “hub motor” provided inside a wheel of a vehicle drive wheel (hereinafter simply referred to as “drive wheel”). This is a device that cools the wheel drive mechanism that rotationally drives the wheel according to the following. This device cools the wheel drive mechanism, in particular by cooling the IWM.

Various vehicles such as automobiles, railway vehicles, and bicycles can be cited as vehicles equipped with IWM. In the present embodiment, an automobile will be described as an example.
In the following description, the side close to the axis of the drive wheel is the inner peripheral side, the opposite side is the outer peripheral side, the vehicle center side in the vehicle width direction is the inner side, and the opposite side is the outer side. The upstream and downstream directions are determined with reference to the rotation direction of.

[First embodiment]
[1. Constitution]
First, the structure of the drive wheel which is a premise of the cooling device for the wheel drive mechanism according to the present embodiment will be described.

[1-1. Drive wheel]
As shown in FIG. 1, the drive wheel 1 has a wheel 2 and a tire 3 attached to the outer periphery of the wheel 2 that rotates around an axis C thereof.
The wheel 2 has a rim 2a disposed so as to form a cylindrical surface on the outer periphery, and a disk 2b provided on the inner peripheral side of the rim 2a. The disc 2b is coupled to the rim 2a and forms a wall portion on the outer side of the wheel 2 in the vehicle width direction. For this reason, it can be said that a space is formed on the inner peripheral side of the rim 2 a and on the inner side in the vehicle width direction of the disk 2 b, that is, inside the wheel 2.

A central portion of the disk 2b is coupled and fixed to an output shaft 11 of the IWM 10 described later. For this reason, the drive wheel 1 is driven by the output rotation of the IWM 10.
A brake mechanism 4 is interposed between the disk 2 b of the wheel 2 and the IWM 10. The brake mechanism 4 includes a rotor 4a that rotates integrally with the wheel 2, and a caliper 4b that brakes the rotation of the rotor 4a. For this reason, when the rotation of the rotor 4a is braked by the caliper 4b, the wheel 2 (the driving wheel 1) is braked by the brake mechanism 4.

The caliper 4b is connected to a vehicle body structure (not shown). FIG. 1 shows an example in which the rotor 4a of the brake mechanism 4 is interposed between the center portion of the disk 2b and the output shaft 11.
Inside the wheel 2 described above, an IWM 10 and a casing 20 disposed on the outer periphery thereof are accommodated.
Hereinafter, each component will be described in the order of the IWM 10 and the casing 20.

[1-2. IWM (In-wheel motor)]
The IWM 10 is a power source that rotationally drives the drive wheels 1 and operates by supplying power from a battery (not shown).
This IWM10 classifies the gap between the rotor and the stator into a method in which the gap is formed in the radial direction (radial gap method) and a method in which the gap is formed in the axial direction (axial gap method). In addition, regarding the relationship between the output shaft and the wheel, a reduction mechanism is interposed between the output shaft and the wheel, and the direct drive system (motor output rotational speed = wheel rotational speed) in which these are directly connected. Can be classified into those of the gear reduction method (motor output rotational speed> wheel rotational speed). These various known electric motors can be applied as the IWM 10. When a radial gap type electric motor is used, any of an outer rotor type and an inner rotor type classified according to the location of the rotor relative to the stator may be applied.

Here, the IWM 10 will be described as an example using an axial gap type and direct drive type electric motor.
The IWM 10 includes an output shaft 11 and a housing 12 that are arranged concentrically with the axis C of the drive wheel 1. The output shaft 11 is rotatably supported at the center of the housing 12 via a bearing.
The output shaft 11 is provided such that the vehicle width direction outer end portion 11 a protrudes from the housing 12. The brake mechanism 4 and the wheel 2 described above are coupled to the outer end 11a in the vehicle width direction.

  FIG. 1 shows an example in which the output shaft 11 is formed hollow. In this case, the IWM 10 and the drive wheel 1 can be rotatably supported by disposing a support shaft (not shown) on the vehicle body side through a bearing or the like in the hollow portion of the output shaft 11. Alternatively or in addition, the housing 12 may be coupled to the structure on the vehicle body side, and the IWM 10 and the drive wheel 1 may be supported. On the other hand, the output shaft 11 may be formed solid. In this case, the IWM 10 and the drive wheel 1 can be supported by coupling the solid output shaft 11 and the housing 12 to the structure on the vehicle body side.

  The housing 12 includes a housing main body 13 that houses a rotor 15 and a stator 16 (here, only one of the stators is attached) that generates a rotational driving force, and a vehicle width direction end of the housing main body 13. And a protrusion 14 projecting in the radial direction over the entire circumference. The protrusions 14 are arranged in parallel in the axial direction, and a space (hereinafter referred to as “concave portion”) 14 a sandwiched between the protrusions 14 is formed.

  The housing main body 13 is formed in a cylindrical shape having a hollow closed space. The rotor 15 and the stator 16 are accommodated in this hollow closed space. That is, the housing main body 13 is a housing that protects the rotor 15 and the stator 16 accommodated therein by preventing dust and water from entering. The hollow closed space in the housing body 13 has a columnar shape smaller than the columnar shape formed by the housing body 13 by an amount corresponding to the thickness.

Hereinafter, the rotor 15 and the stator 16 housed in the housing body 13 will be described, and then the protrusions 14 provided on the outer periphery of the housing body 13 will be described.
The rotor 15 rotates with respect to the stator 16. The rotor 15 and the stator 16 are both arranged concentrically with the axis C.

  The rotor 15 has a central portion 15a fixed to the output shaft 11, and a plurality of permanent magnets (all not shown) are fixed in an annular shape on the outer side and the inner side of the outer peripheral portion 15b. Such a permanent magnet is magnetized so that adjacent poles in the circumferential direction have different polarities, and is formed in, for example, a fan shape. The outer peripheral portion 15b of the rotor 15 is sandwiched between stators 16 provided on both sides in the vehicle width direction (axial direction) at an interval.

The stator 16 is fixed to the outer peripheral portion 13a of the housing body 13, and a plurality of coil modules each having a coil wound around a magnetic core are arranged in an annular shape. Each coil module is formed in a fan shape, for example. The stator 16 is integrally joined to the casing 20 described later via the housing 12.
When a current is supplied to each coil module of the stator 16, the rotor 15 rotates with respect to the stator 16 by the magnetic force (attraction or repulsion) between each coil module of the stator 16 and the permanent magnet of the rotor 15, and the output shaft 11. Rotational driving force is output from. At this time, each coil module generates heat when current flows through the stator 16. For example, at the time of high load output or continuous operation of the IWM 10, a large amount of current or a current is supplied to each coil module of the stator 16 over a long period of time, and the amount of heat generated by the IWM 10 increases.

The protruding portion 14 is formed in order to dispose a casing 20 described below. That is, the protrusion 14 is for coupling the casing 20 to the housing 12.
Although FIG. 1 illustrates an example in which the housing main body 13 and the protrusion 14 are integrally formed, each of them may be formed separately and combined. Further, the housing main body 13 may also have a structure in which members divided at an arbitrary location are coupled.

[1-3. casing]
The casing 20 is formed in a substantially cylindrical shape and is disposed on the outer periphery of the IWM 10. Specifically, the casing 20 is formed in an annular shape, and the radial cross section is formed in a U shape (for example, an inverted U shape in the upper portion) with the axis C at the top. The inner peripheral end of the casing 20 and the outer peripheral end of the IWM 10 (that is, the outer peripheral end of the protrusion 14 in the housing 12) are coupled. For coupling the casing 20 and the IWM 10, known coupling means such as welding or bolt fastening can be used.

As shown in FIGS. 1 to 3, the casing 20 is provided with a plurality of openings 21 (reference numerals only at one place) along the rotation direction of the wheel 2 (indicated by double arrows in FIGS. 2 and 3). ) Is provided. In addition, the rotation direction of the wheel 2 is the same direction as the direction (outer peripheral direction) in which the outer periphery of the casing 20 extends.
In the casing 20, a plurality of lid members 30 (corresponding to only one place) provided corresponding to each of the openings 21, and a heat-sensitive member 40 that opens and closes the openings 21 by each lid member 30 (one 1 are provided with reference numerals only, and are not shown in FIG. 1). Here, one lid member 30 is provided for one opening 21.

FIG. 2 illustrates an example in which twelve openings 21 are formed at equal intervals in the circumferential direction, but the number of openings 21 may be set according to the surrounding configuration, required specifications, and the like. For example, one may be sufficient. Further, the intervals between the openings 21 may not be equal. In this case, the numbers and locations of the lid member 30 and the heat sensitive member 40 correspond to the openings 21.
Hereinafter, the opening 21, the lid member 30, and the heat sensitive member 40 will be described in this order.

[1-3-1. Aperture]
When the opening 21 is closed (covered by the lid member 30), communication between the outer peripheral side and the inner peripheral side of the casing 20 is blocked. Therefore, a closed space is formed by the opening 21 and the recess 14a (see FIG. 1) formed at the radial end of the housing 12 in the IWM 10.

  On the other hand, as shown in FIG. 4, the opening 21 allows the outer peripheral side and the inner peripheral side of the casing 20 to communicate with each other when the opening 21 is opened. For this reason, the opening 21 can be regarded as an inlet for introducing outside air (air on the outer peripheral side of the casing 20) into the recess 14a (both see FIG. 1) at the radial end of the housing 12, The air in the recess 14 a can be regarded as a discharge port that discharges the air to the outside of the casing 20. That is, the opening 21 can be regarded as a ventilation port for replacing the air in the recess 14a.

[1-3-2. Lid member]
The lid member 30 is configured to be elastically deformable. In other words, the lid member 30 has flexibility that can be restored to a predetermined shape. In addition, the cover member 30 should just be comprised so that at least the base end part 30a can be elastically deformed.
As shown in FIGS. 2 to 4, the base end 30 a of the lid member 30 is coupled to the downstream edge 22 a on the downstream side in the rotation direction of the wheel 2 at the peripheral edge 22 of the opening 21. That is, the lid member 30 has the distal end portion 30b disposed on the upstream side in the rotation direction of the wheel 2 relative to the proximal end portion 30a.

A heat sensitive member 40, which will be described in detail later, is disposed at a joint portion (hereinafter referred to as “joint portion”) 50 between the lid member 30 and the casing 20. Note that portions other than the base end portion 30 a of the lid member 30 are not coupled to the casing 20.
Here, the lid member 30 is integrally coupled to the casing 20.

  If the external force from the heat-sensitive member 40, which will be described in detail later, does not act, the lid member 30 has a predetermined shape and covers (closes) the opening 21. In such a state, as shown in FIGS. 2 and 3, the outer periphery of the casing 20 is formed in a shape that forms a cylindrical surface. In other words, when the lid member 30 covers the opening 21, a smooth cylindrical surface is formed on the outer periphery of the casing 20.

[1-3-3. Heat sensitive member]
By the way, when the IWM 10 (see FIG. 1) generates heat, heat is transmitted through the housing 12 (see FIG. 1) of the IWM 10, and the temperatures of the casing 20, the lid member 30, and the heat sensitive member 40 also rise. That is, each of the casing 20, the cover member 30, and the heat sensitive member 40 increases its own temperature as the temperature of the IWM 10 increases. The cooling device for the wheel drive mechanism according to the present embodiment opens and closes the opening 21 using such a temperature change. The heat sensitive member 40 that can be said a power source for opening and closing will be described below.

The heat sensitive member 40 is made of a material having a higher coefficient of thermal expansion than the casing 20 and the lid member 30. For example, an aluminum material can be used for the heat sensitive member 40, and a steel material can be used for the casing 20 and the lid member 30.
As described above, the heat-sensitive member 40 is disposed in the coupling portion 50 where the base end portion 30a of the lid member 30 and the casing 20 are coupled. Specifically, the heat sensitive member 40 is accommodated in the concave portion 29 provided in the coupling portion 50. 3 and 4 exemplify those in which the heat sensitive member 40 is formed in an axial shape (columnar shape).

  As shown in FIG. 5, the recess 29 has a main body portion 29 a provided on the downstream side in the rotation direction of the wheel 2 and a throttle portion 29 b provided on the upstream side in the rotation direction of the wheel 2. The main body portion 29 a is a portion that is recessed in a shape corresponding to the heat-sensitive member 40, and is a portion that houses the heat-sensitive member 40. The narrowed portion 29b is a portion formed such that the distance between the peripheral edge 22 of the opening 21 and the lid member 30 decreases (throttles) from the main body portion 29a toward the upstream side in the rotation direction of the wheel 2.

  Strictly speaking, since the volume of the heat sensitive member 40 changes according to the temperature, the main body portion 29a of the recess 29 is recessed in a shape corresponding to the outer diameter of the heat sensitive member 40 at a predetermined temperature. The predetermined temperature here is a safe side (by a predetermined margin) with respect to the temperature that the heat sensitive member 40 can take when the IWM 10 is at a temperature at which it is overheated (overheated) or overcooled (cooled). A temperature on the high temperature side or the low temperature side) can be used.

The heat-sensitive member 40 can be disposed by being fitted and inserted along the axial direction into the main body 29 a of the recess 29 provided in the casing 20. Further, the front end portion 30b (see FIG. 4 and the like) of the lid member 30 is displaced so that the distance between the narrowed portion 29b of the recess 29 and the lid member 30 is larger than the outer periphery (outer shape) of the heat-sensitive member 40 (see FIG. 4 and the like). It is also possible to open the opening 21 greatly and arrange it from between the lid member 30 and the peripheral edge 22 of the opening 21.
Although not shown in the drawing, the heat-sensitive member 40 is subjected to an appropriate retaining process so that the heat-sensitive member 40 does not fall out of the recess 29. Examples of the retaining process include providing heads at both axial ends of the heat-sensitive member 40 and adding a retaining pin.

  When the IWM 10 (see FIG. 1) generates heat, the temperature of the heat sensitive member 40 rises as the temperature of the IWM 10 rises, and the volume of the heat sensitive member 40 expands. At this time, due to the difference in thermal expansion coefficient between the casing 20 and the lid member 30 and the heat-sensitive member 40, the heat-sensitive member 40 is located at the base end portion of the lid member 30 as shown by the two-dot chain line in FIGS. 30a is pushed up, and accordingly, the front end portion 30b (see FIGS. 2 to 4) of the lid member 30 is separated from the upstream edge portion 22b on the upstream side in the rotation direction of the wheel 2 at the peripheral edge 22 of the opening portion 21. Part 21 is opened.

[2. Action and Effect]
Since the cooling device for a wheel drive mechanism according to the first embodiment of the present invention is configured as described above, the following operations and effects can be obtained.
First, the operation of the cooling device for the wheel drive mechanism according to the present embodiment will be described.
The temperature of the IWM 10 is low at the beginning of startup or when operating in a very cold region. At this time, as shown in FIGS. 2, 3, and 5, the heat sensitive member 40 is not more than a predetermined temperature and is accommodated in the recess 29. For this reason, the lid member 30 is not pushed up by the heat-sensitive member 40 and is in a state of covering the opening 21 (closed state).

On the other hand, the IWM 10 generates a large amount of heat when the load is high or during continuous operation, and the temperature rises. This heat is transmitted to the casing 20, the lid member 30 and the heat sensitive member 40 through the housing 12. Then, the volume of the casing 20 and the lid member 30 including the heat sensitive member 40 expands. At this time, due to the difference in thermal expansion coefficient between the casing 20 and the lid member 30 and the heat sensitive member 40, the base end portion 30a of the lid member 30 is pushed up by the heat sensitive member 40 as shown in FIG. Is elastically deformed (bends) to open the opening 21.
In a state where the opening 21 is opened, the lid member 30 is separated from the peripheral edge 22 of the opening 21 as it goes from the base end portion 30a to the tip end portion 30b.

Hereinafter, the detail of the effect | action which opens the opening part 21 is demonstrated with reference to the dashed-two dotted line of FIG.
When the temperature of the IWM 10 rises, the volume of the heat sensitive member 40 expands. At this time, while being smaller than the volume expansion of the heat-sensitive member 40, the casing 20 and the lid member 30 also undergo a volume expansion minutely. Due to the volume expansion, the heat-sensitive member 40 and the base end portion 30a of the lid member 30 are pressed against each other, and the heat-sensitive member 40 and the recess 29 are pressed against each other. Therefore, the base end portion 30a of the lid member 30 is pushed up by the heat sensitive member 40 and elastically deformed. At this time, in the base end portion 30a of the lid member 30 to be pushed up by the heat sensitive member 40, the downstream side is more rigid than the upstream side in the rotation direction of the wheel 2, and therefore the lid member 30 of the heat sensitive member 40 is. The pushing force is shifted so as to escape from the downstream side in the rotation direction of the wheel 2 to the upstream side (from the rigid portion to the flexible portion), and the heat-sensitive member 40 rotates slightly.

Depending on the rigidity of the lid member 30, the shape of the inner peripheral surface, the shape of the recess 29, etc., the lid member 30 may be pushed up without rotating the heat sensitive member 40.
Since the volumes of the casing 20 and the lid member 30 including the heat-sensitive member 40 have a substantially proportional relationship with respect to the temperature, the degree of opening of the opening 21 depends on the temperature of the IWM 10.

As described above, the cooling device for the wheel drive mechanism of the present embodiment uses the difference in thermal expansion coefficient between the heat sensitive member 40, the casing 20, and the lid member 30 to control the power and control according to the temperature of the IWM 10. However, the degree of opening of the opening 21 is changed without requiring the above.
When the opening 21 is opened, the outer peripheral side and the inner peripheral side of the casing 20 are communicated, and air in the closed space of the opening 21 and the recess 14a formed when the opening 21 is closed is discharged and the opening 21 is opened. Air (outside air) on the outer peripheral side of the casing 20 is introduced into the recess 14a through the portion 21. That is, the air heated in the recess 14a is ventilated.

  If the wheel 2 is rotating at this time, the air flow accompanying this rotation is guided to the lid member 30 which is separated from the peripheral edge 22 of the opening 21 as it goes from the base end 30a to the front end 30b. , Is efficiently introduced into the opening 21. The air introduced from the opening 21 hits the housing 12 and discharges the air in the recess 14a. That is, the air stored in the recess 14a can be discharged, and the heated housing 12 can be cooled.

Next, the effect of the cooling device of the wheel drive mechanism according to the present embodiment will be described.
Since the lid member 30 covering the opening 21 opens the opening 21 in response to the temperature rise of the IWM 10, the air can be exchanged (ventilated) between the inner peripheral side and the outer peripheral side of the casing 20. It is possible to cool the IWM 10 provided on the inner peripheral side of the outside with the outside air. If the wheel 2 is rotating at this time, ventilation will be accelerated | stimulated by the flow of the air accompanying this rotation, and the cooling efficiency of IWM10 can be improved.

On the other hand, when the temperature of the IWM 10 is not increased, the opening 21 is covered with the lid member 30 and the IWM 10 is not cooled. At this time, for example, if the wheel 2 is rotating, air turbulence and air resistance accompanying this rotation can be suppressed. Further, if the IWM 10 is not cooled, cooling of the wheel drive mechanism is also suppressed. Therefore, with the operation of the wheel drive mechanism, the lubricating oil in each part of the mechanism rises in temperature and the viscosity decreases, so that the resistance of the lubrication part can also be suppressed. From these, the energy loss of the wheel drive mechanism at low temperatures can be suppressed.
Thus, since the lid member 30 opens and closes the opening 21 according to the temperature of the IWM 10, the IWM 10 can be appropriately cooled.

  Further, in order to cool the IWM 10, it is only necessary to provide the substantially cylindrical casing 20 formed with the opening 21 that is opened and closed by the lid member 30 on the outer periphery of the IWM 10. As a result, the degree of freedom in dealing with layout constraints can be improved, and an increase in cost can be suppressed. As a result, the cooling device of the wheel drive mechanism can contribute to weight reduction and can contribute to improvement of durability.

Further, since the volume of the heat sensitive member 40 expands as the temperature of the IWM 10 increases, the lid member 30 opens the opening 21, so that control of opening of the opening 21 is not required and power can be consumed. Absent. Therefore, it can be set as a simple structure.
Since the heat sensitive member 40 opens the opening 21 by the lid member 30 so that the temperature of the IWM 10 corresponds to the degree of opening of the opening 21, the IWM 10 can be reliably cooled.

  When the lid member 30 covers the opening 21, that is, when the temperature of the IWM 10 is not increased, a cylindrical surface is formed on the outer periphery of the casing 20, and thus air turbulence and air when the wheel 2 is rotating Resistance can be further suppressed. Thereby, energy loss can be further suppressed.

Since the stator 16 of the IWM 10 and the casing 20 are integrally joined, the wheel 2 rotates while the casing 20 does not rotate. Under such a structure, the lid member 30 has the distal end portion 30b disposed on the upstream side in the rotational direction of the wheel 2 relative to the proximal end portion 30a. Accordingly, the air flow can be efficiently introduced into the opening 21 and the cooling efficiency of the IWM 10 can be improved.
Since the IWM 10 of the axial gap type is used, it is advantageous for downsizing as compared with the radial gap type, and the degree of freedom for the layout can be further improved.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. The cooling device for a wheel drive mechanism according to the second embodiment of the present invention differs from the first embodiment in the configuration of the lid member. Except for the points described here, the configuration is the same as that of the first embodiment, and the same reference numerals are given thereto, and the description of each part is omitted.

As shown in FIG. 6, in the cooling device for the wheel drive mechanism according to the present embodiment, the lid member 60 is made of bimetal. Bimetal is obtained by bonding two metal members having different coefficients of thermal expansion into a single plate by, for example, a rolling method.
The lid member 60 includes a first metal member 61 on the outer peripheral side and a second metal member 62 on the inner peripheral side.

  A member having a lower thermal expansion coefficient than the second metal member 62 is used for the first metal member 61. As the first metal member 61, various members can be adopted as long as the metal member has a low coefficient of thermal expansion such as Invar. Further, as the second metal member 62, various members can be adopted as long as they are metal members having a high coefficient of thermal expansion, such as nickel chromium iron alloy, nickel manganese iron alloy, manganese copper iron alloy.

Here, two metal members 61 and 62 are provided from the base end portion 60 a of the lid member 60 to the entire tip portion (not shown). However, as shown by a two-dot chain line in FIG. 6, two metal members 61 and 62 may be provided only at the base end portion 60 a of the lid member 60.
FIG. 6 shows the coupling portion 50 to which the lid member 60 is coupled provided with the recess 29, but the recess 29 may be omitted.

As the temperature of the lid member 60 rises, the second metal member 62 on the inner peripheral side expands more than the first metal member 61 on the outer peripheral side, and the base end 60a moves toward the outer peripheral side as the fulcrum. Deforms toward. This deformation amount and the temperature of the lid member 60 (metal members 61 and 62) have a one-to-one correspondence.
In other words, the lid member 60 can be said to have a proportional relationship between the temperature and the degree of opening of the opening 21 as in the lid member 30 of the first embodiment described above. It can be said that the temperature of the IWM 10 and the degree of opening of the opening 21 by the lid member 60 also correspond.

Since the cooling device for the wheel drive mechanism according to the second embodiment is configured as described above, in addition to the effects of the cooling device for the wheel drive mechanism according to the first embodiment, the following effects can be obtained.
Since the lid member 60 is made of bimetal, the opening 21 is opened according to the temperature rise of the IWM 10 without requiring the heat sensitive member 40 unlike the cooling device of the wheel drive mechanism according to the first embodiment. be able to. For this reason, it can be set as a still simpler structure. As a result, it can contribute to cost reduction and durability improvement.

Further, by utilizing the difference in the coefficient of thermal expansion between the first metal member 61 and the second metal member 62 of the lid member 60, the degree of opening of the opening 21 can be adjusted according to the temperature of the IWM 10 without requiring power or control. Can be changed.
If the two metal members 61 and 62 are provided only at the base end portion 60a of the lid member 60, the material cost can be suppressed. Further, if the formation of the recess 29 is omitted, the formation cost can be suppressed.

[Others]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Each structure of 1st embodiment and 2nd embodiment mentioned above can be selected as needed, and may be combined suitably.
In the above-described embodiment, an example in which the opening 21 is formed in a rectangular shape is illustrated, but the shape of the opening 21 may be various shapes such as a columnar shape and a slit shape. For example, the shape of the opening 21 may be designed in consideration of the air flow when the opening 21 is opened. Specifically, if attention is paid to the point that the air on the outer peripheral side of the casing 20 is introduced through the opening 21, it has an axis or side that is inclined with respect to the radial direction so as to follow the flow direction of the introduced air. A shape may be adopted. In this case, the efficiency of introducing outside air to the inner peripheral side of the casing 20 is improved, and the cooling effect of the IWM 10 can be improved.

In addition, the lid member 30 has been described as being connected to the downstream edge 22a on the downstream side in the rotation direction of the wheel 2 at the peripheral edge 22 of the opening 21. It is only necessary that a part of the peripheral edge 22 of the lid member 30 is coupled.
Further, it is sufficient that at least one opening 21 is provided. Furthermore, it is good also as a structure which is not restricted to what provided the one cover member 30 with respect to the one opening part 21, and one cover member covers a some opening part. It is good also as a structure which covers one opening part.
Moreover, the shape of the outer peripheral side in the cover member 30 can be made into various shapes, and various shapes can be formed on the outer periphery of the casing 20 in a state in which the cover member 30 covers the opening 21 without being limited to the cylindrical surface. .

In the first embodiment described above, the heat sensitive member 40 is illustrated as having an axial shape (cylindrical shape), but various shapes such as a spherical shape and a rectangular shape may be adopted as the shape of the heat sensitive member 40. it can. In this case, the recess 29 is provided in a shape corresponding to the heat-sensitive member 40.
In the second embodiment described above, the lid member 60 is made of bimetal and the heat sensitive member 40 of the first embodiment can be omitted. However, the lid member 60 is made of bimetal and heat sensitive. A member 40 may be provided. In this case, the opening / closing of the opening 21 by the lid member 60 can be further ensured.

1 Drive wheel (vehicle drive wheel)
2 wheel 2a rim 2b disk 3 tire 4 brake mechanism 4a rotor 4b caliper 10 IWM (in-wheel motor, electric motor)
DESCRIPTION OF SYMBOLS 11 Output shaft 11a Car width direction outer side end 12 Housing 13 Housing main-body part 13a Outer peripheral part 14 Projection part 14a Recess 15 Rotor 15a Center part 15b Outer peripheral part 16 Stator 20 Casing 21 Opening part 22 Peripheral edge 22a Downstream edge part 22b Upstream edge part 29 Concave part 29a Main body part 29b Restriction part 30 Lid member 30a Base end part 30b Tip part 40 Heat sensitive member 50 Coupling part 60 Lid member (bimetal)
60a Base end portion 61 First metal member 62 Second metal member C Axle

Claims (6)

In a wheel drive mechanism that rotationally drives the wheel by an electric motor provided inside a wheel of a vehicle drive wheel,
A substantially cylindrical casing disposed on the outer periphery of the electric motor and having at least one opening formed therein;
A lid member that covers the opening and opens the opening in response to a temperature rise of the electric motor;
A coupling portion in which a part of the periphery of the opening is coupled to a part of the periphery of the lid member corresponding to the opening;
A heat-sensitive member disposed in the coupling portion and having a volume that expands more than the lid member in response to a temperature rise of the electric motor,
The cooling device for a wheel drive mechanism, wherein the lid member opens the opening when the volume of the heat sensitive member expands . Aluminum material is used for the heat sensitive member,
2. The cooling device for a wheel drive mechanism according to claim 1 , wherein a steel material having a lower thermal expansion coefficient than the aluminum material is used for the lid member and the casing. The cooling device for a wheel drive mechanism according to claim 1, wherein the lid member is made of bimetal. Wherein in the state in which the cover member covers the opening, characterized in that the cylindrical surface is formed on the outer periphery of the casing, the cooling system of the wheel drive mechanism according to any one of claims 1-3. The stator of the electric motor and the casing are integrally joined,
The lid member has a base end coupled to a downstream edge on the downstream side in the rotation direction of the wheel at the periphery of the opening, and a tip at the periphery of the opening in response to a temperature rise of the electric motor. The wheel drive mechanism cooling device according to any one of claims 1 to 4 , wherein the cooling device is separated from an upstream edge on the upstream side in the rotation direction. A plurality of the openings are provided along the outer peripheral direction of the casing,
The cooling device for a wheel drive mechanism according to any one of claims 1 to 5 , wherein a plurality of the lid members are provided corresponding to the respective openings.

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