JP7270403B2 - In-wheel motor drive - Google Patents

Description

TECHNICAL FIELD The present invention relates to an in-wheel motor drive device arranged inside a wheel, and more particularly to a wheel hub bearing portion that rotatably supports a hub wheel connected to the wheel.

An in-wheel motor called a drive unit in Japanese Patent No. 5872358 (Patent Document 1) has an inner ring coupled to a road wheel of a wheel and a bearing case supporting the inner ring via rolling elements. These inner and outer rings constitute wheel hub bearings. The bearing case of Patent Document 1 is fixed to the knuckle with bolts. The speed reducer case of the in-wheel motor is also fixed to the knuckle with bolts.

An in-wheel motor described in Japanese Patent Laying-Open No. 2016-187252 (Patent Document 2) has an inner ring coupled to a wheel and an outer ring member supporting the inner ring via rolling elements. These inner and outer rings constitute wheel hub bearings. The outer ring member of Patent Document 2 is directly fixed to the reduction section casing with bolts.

Japanese Patent No. 5872358 JP 2016-187252 A

In Patent Document 1, the bearing case is arranged axially outside, the reduction gear case is arranged axially inside, and a knuckle is interposed between the bearing case and the reduction gear case. Then, the axial thickness of the knuckle of Patent Document 1 is large with respect to the axial direction of the in-wheel motor, and there is room for reducing the axial dimension of the in-wheel motor by thinning the knuckle.

In Patent Document 2, the outer ring member is arranged axially outside, the reduction section casing is arranged axially inside, and a bolt extending in the axial direction penetrates the outer ring member and is screwed into the reduction section casing. Therefore, no member is interposed between the outer ring member and the reduction section casing, and the axial dimension of the in-wheel motor is shortened. However, the axle load borne by the wheels may be input to the reduction section casing. As a result, the speed reducer casing is deformed, causing misalignment of the gear shaft supported by the speed reducer casing inside the speed reducer, which may worsen the noise and vibration of the in-wheel motor.

As one countermeasure, it is conceivable to increase the wall thickness of the reduction section casing of Patent Document 2, but this increases the axial dimension of the in-wheel motor. As other countermeasures, it is conceivable to increase the diameter dimensions of the inner and outer ring members, increase the pitch diameter (PCD) of the wheel hub bearing, or move the bolt to the outer diameter side. A special bearing design is required, which leads to an increase in cost.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an in-wheel motor drive device that can use existing wheel hub bearings without changing the pitch diameter of the wheel hub bearings.

For this purpose, the in-wheel motor drive device according to the present invention has an inner ring, an outer ring, and a plurality of rolling elements arranged in an annular gap between the inner ring and the outer ring, and is accommodated in an inner hollow area of a road wheel fixed to the inner ring. a wheel hub bearing portion that drives the inner ring; a motor portion that has a diameter smaller than that of the road wheel and is housed in the hollow region inside the road wheel; and a hub attachment fixed to the casing housing the rotating shaft.

According to the present invention, the hub attachment is fixed to the outer ring by the first bolt on the one hand and fixed to the casing by the second bolt on the other hand, so the casing is not directly fixed to the outer ring. Therefore, no shaft load is input to the casing, and misalignment of the motor rotating shaft and gear shaft does not occur. In addition, since the outer ring is fixed to the casing through the hub attachment, the second bolt can be easily installed by increasing the diameter of the hub attachment without increasing the diameter of the outer ring and the pitch diameter (PCD) of the wheel hub bearing. It can be arranged on the outer diameter side of the outer ring. Therefore, an in-wheel motor drive device can be manufactured using existing wheel hub bearings, which is advantageous in terms of cost. Alternatively, the diameter of the wheel hub bearing portion can be made smaller than before. Further, by setting the head of the first bolt and/or the second bolt to the outer side in the vehicle width direction and the shaft portion to the inner side in the vehicle width direction, the hub attachment and/or the wheel hub bearing portion is attached and detached from the outer side in the vehicle width direction. This improves work efficiency in assembling and disassembling the in-wheel motor drive device. According to the present invention, even if the shape of the outer ring and the shape of the casing do not correspond to each other and the two cannot be directly connected, the hub attachment can be interposed between the two to indirectly connect them.

The casing that accommodates the motor rotating shaft also accommodates the rotor and stator of the motor section, but may also accommodate other parts such as a speed reduction mechanism composed of a plurality of gears and rotating elements. A reduction section that reduces the rotation output from the motor rotating shaft and transmits the reduced rotation to the inner ring may be provided adjacent to the motor section, and the casing of the motor section and the casing of the reduction section may be shared. In this case, the hub attachment is fixed to the casing of the motor section or the casing of the reduction section with the second bolt. The positional relationship between the first and second bolts is not particularly limited. In one aspect of the present invention, the second bolt is arranged radially outward of the first bolt with respect to the axis of the wheel hub bearing portion. According to this aspect, the outer diameter of the outer ring can be made smaller than the outer diameter of the hub attachment.

As a preferred aspect of the present invention, the motor has an input shaft connected to the rotation shaft of the motor, an output shaft connected to the inner ring of the wheel hub bearing, and an output gear connected to the output shaft to reduce the rotation of the input shaft. A deceleration part for transmission to the output shaft is further provided, and the first bolt is arranged so as to overlap the output gear when viewed in the axial direction of the wheel hub bearing part. According to this aspect, the outer diameter of the outer ring can be made smaller than the outer diameter of the output gear, and the diameter of the wheel hub bearing portion can be reduced in the radial direction. When viewed in the axial direction of the wheel hub bearing portion, the first bolt is arranged so as to overlap the output gear, which means that the distance from the axis to the first bolt is greater than the radius of the addendum circle of the output gear centered on the axis. is also small.

As a further preferred aspect of the present invention, the second bolt is arranged on the outer diameter side of the output gear when viewed in the axial direction of the wheel hub bearing portion. According to this aspect, a large number of second bolts can be arranged in a spaced apart manner in the circumferential direction. In addition, since the female threaded hole into which the second bolt is screwed is separated from the output gear, the casing portion in which the female threaded hole is formed is made thicker than the other casing portions to partially increase the rigidity of the casing. be able to. Therefore, even if the axle load is transmitted to the second bolt, deformation of the casing can be prevented. In addition, when viewed in the axial direction of the wheel hub bearing portion, the second bolt is arranged on the outer diameter side of the output gear, which means that the distance from the axis to the second bolt is the tip circle of the output gear centered on the axis. is greater than the radius of

As one aspect of the present invention, the hub attachment is fitted with the casing and positioned coaxially with the output shaft of the reduction section. According to this aspect, since the hub attachment is naturally positioned with respect to the casing during the assembly work of the in-wheel motor drive device, the assembly work is made more efficient. Also, assembly accuracy is improved. As for the fitting of the hub attachment and the casing, for example, they are assembled by fitting the recesses and projections of both with spigots.

As one aspect of the present invention, the outer ring is fitted with the casing and positioned coaxially with the output shaft of the reduction section. According to this aspect, since the outer ring is naturally positioned with respect to the casing during the assembly work of the in-wheel motor drive device, the assembly work is made more efficient. As the fitting of the outer ring and the casing, for example, a spigot is used to fit the recesses and projections of both to assemble them.

As one aspect of the present invention, the brake disc further includes a brake disc having a brake friction surface on an outer diameter region and an inner diameter region fixed to the inner ring of the wheel hub bearing, wherein at least a portion of the first bolt and the second bolt It is arranged on the inner diameter side of the brake friction surface of the brake disc. According to this aspect, the diameter of the wheel hub bearing portion can be reduced in the radial direction. As such an aspect, for example, when viewed in the axial direction of the wheel hub bearing portion, the inner diameter region of the brake disc overlaps at least a portion of the first bolt or the second bolt. The number of bolts arranged on the inner diameter side of the brake friction surface of the brake disc is not particularly limited. Either one of the first bolt and the second bolt may be arranged on the inner diameter side of the brake friction surface.

In one aspect of the invention, the inner diameter region of the brake disc is axially located to one side of the outer diameter region, the brake disc further has an annular step connecting the inner diameter region and the outer diameter region, the annular step and The inner diameter region constitutes a hat portion defining a hollow cylindrical region, and at least a portion of the first bolt and the second bolt are arranged in the hollow region of the hat portion. According to this aspect, the axial position of the brake disc and the axial position of the first bolt or the second bolt can be overlapped. Therefore, the diameter of the in-wheel motor drive device including the brake disc can be reduced in the axial direction. In addition, at least part of the first bolt and the second bolt means that the bolt end portion, for example, the bolt head portion, is accommodated in the inner hollow region of the hat portion. The type and number of bolts arranged in the hollow region of the hat portion are not particularly limited. Either one of the first bolt and the second bolt may be arranged in the hollow region of the hat portion.

Thus, according to the present invention, an in-wheel motor drive device can be manufactured using existing wheel hub bearings. In addition, since the axle load is not directly input to the casing from the wheel hub bearing, deformation of the casing can be prevented.

1 is a schematic developed cross-sectional view showing an in-wheel motor drive device according to an embodiment of the present invention; FIG. It is a typical sectional view showing the inside of the same embodiment. It is a typical front view which shows the same embodiment. It is a typical longitudinal section showing a wheel hub bearing part of the embodiment. It is a figure which shows the state which looked at the same embodiment from the vehicle width direction outer side. It is a figure which extracts and shows the front part of the wheel hub bearing part in FIG. 5, and a reduction part casing. It is a figure which shows the state which looked at the structure shown in FIG. 6 from the inside side of the in-wheel motor drive device. Figure 7 is a perspective view of the structure shown in Figure 6; FIG. 9 is an exploded perspective view of the structure shown in FIG. 8; FIG. 8 is a diagram showing a state in which gears are attached to the structure shown in FIG. 7; FIG. 4 is a cross-sectional view showing portions connected by bolts; It is sectional drawing which extracts and shows the wheel hub bearing part of the same embodiment. It is a perspective view which shows the same embodiment. It is a sectional view showing a sensor attachment place. It is a figure which shows the state which looked at the in-wheel motor drive device of this embodiment, and its peripheral structure from the vehicle rear.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail based on the drawings. FIG. 1 is a developed cross-sectional view showing an in-wheel motor drive device according to an embodiment of the present invention. In FIG. 1 , the right side of the paper represents the inner side in the vehicle width direction (inboard side), and the left side of the paper represents the outer side in the vehicle width direction (outboard side). The cross section shown in FIG. 1 is a developed plane connecting the plane including the axis M and the axis N shown in FIGS. 2 and 3 and the plane including the axis N and the axis O in this order.

FIG. 2 is a schematic cross-sectional view showing the interior of the same embodiment, showing a state in which the in-wheel motor drive device is cut along II-II in FIG. 1 and the cross section is viewed in the direction of the arrow. FIG. 3 is a schematic front view showing the same embodiment, showing a state in which the in-wheel motor drive device is viewed from the outside in the vehicle width direction. In order to avoid complication of the drawing, each gear is represented by an addendum circle in FIG. In FIGS. 2 and 3, the right side of the paper indicates the rear of the vehicle, the left side of the paper indicates the front of the vehicle, the upper side of the page indicates the upper side of the vehicle, and the lower side of the page indicates the lower side of the vehicle. 2 and 3, the vehicle width direction inner side (inboard side) is viewed from the vehicle width direction outer side (outboard side) in the axis O direction.

FIG. 4 is a vertical cross-sectional view showing the wheel hub bearing portion of the same embodiment, showing a cut surface when the wheel hub bearing portion is cut along a plane including the axis O. FIG. To avoid drawing clutter, FIG. 4 shows only half of the brake disc and road wheel.

As shown in FIG. 1, the in-wheel motor drive device 10 includes a wheel hub bearing portion 11 provided at the center of a wheel (not shown), a motor portion 21 that drives the wheel, and a wheel hub bearing portion that decelerates rotation of the motor portion. and a deceleration unit 31 that transmits to the unit 11 . The motor portion 21 and the reduction portion 31 are arranged offset from the axis O of the wheel hub bearing portion 11 . The axis O extends in the vehicle width direction and coincides with the axle. Regarding the position in the direction of the axis O, the wheel hub bearing portion 11 is arranged on one side (outboard side) of the in-wheel motor drive device 10 in the axial direction, and the motor portion 21 is arranged on the other side (inboard side) of the in-wheel motor drive device 10 in the axial direction. , the speed reduction section 31 is arranged on one side of the motor section 21 in the axial direction, and the axial position of the speed reduction section 31 overlaps the axial position of the wheel hub bearing section 11 .

The in-wheel motor drive device 10 is a vehicle motor drive device that drives wheels of an electric vehicle. The in-wheel motor drive device 10 is connected to a vehicle body (not shown). The in-wheel motor drive device 10 can run the electric vehicle at a speed of 0 to 180 km/h.

The wheel hub bearing portion 11 is a rotating inner ring/fixed outer ring, and includes an inner ring 12 as a rotating ring (hub ring) coupled to a road wheel (not shown) and a fixed ring coaxially arranged on the outer diameter side of the inner ring 12. It has an outer ring 13 and a plurality of rolling elements 14 arranged in an annular space between the inner ring 12 and the outer ring 13 .

Referring to FIG. 1, the outer ring 13 passes through an opening 39p formed in the front portion 39f of the main body casing 39. As shown in FIG. The main body casing 39 is a casing that includes the outer shell of the reduction section 31 and accommodates the rotating elements of the reduction section 31 . The front portion 39f is a casing wall portion that covers one end of the reduction section 31 in the direction of the axis O in the main casing 39. As shown in FIG. A cylindrical portion 39c is formed along the edge of the opening 39p in the front portion 39f. The cylindrical portion 39c protrudes in one direction along the axis O from the outer wall surface of the front portion 39f. The greater the projection length, the greater the axial length of the opening 39p.

A plurality of outer ring projecting portions 13g are further provided on the outer peripheral surface of the outer ring 13 at different positions in the circumferential direction. A cylindrical region of the outer ring 13 on the other side in the direction of the axis O from the outer ring projecting portion 13g is inserted into the opening 39p of the front portion 39f. At this time, the other surface of the outer ring projecting portion 13g in the direction of the axis O contacts the tip of the cylindrical portion 39c, and the outer ring 13 is positioned in the direction of the axis O. As shown in FIG.

4, the outer diameter dimension of the outer peripheral surface 13b of the outer ring 13 on the other side in the direction of the axis O is substantially the same as the inner diameter dimension of the opening 39p, and the outer ring 13 is tightly fitted into the opening 39p. It is better to let Here, the fitting between the outer peripheral surface 13b and the opening 39p may be tight fitting. By fitting the outer ring 13 to the main body casing 39 in this manner, the wheel hub bearing portion 11 is positioned coaxially with the output shaft 38 of the reduction portion 31 .

A through hole 13h is formed in each outer ring projecting portion 13g projecting in the outer diameter direction. A hub attachment 61 is arranged adjacent to the other side of the outer ring projecting portion 13g in the direction of the axis O. As shown in FIG. The hub attachment 61 is a plate member having a thickness in the direction of the axis O, and has a central hole extending along the axis O, into which the cylindrical portion 39c of the main body casing 39 is inserted. At this time, the outer peripheral surface of the cylindrical portion 39c is fitted with the inner peripheral surface 61n of the hub attachment 61. As shown in FIG. The hub attachment 61 is interposed between each outer ring projecting portion 13g on one side in the axis O direction and the front portion 39f on the other side in the axis O direction.

A plurality of female screw holes 61 f are formed in the hub attachment 61 . 61 f of female screw holes are formed in the inner diameter side part of the hub attachment 61, and are arranged in multiple numbers at intervals in the circumferential direction. Each female threaded hole 61f of the hub attachment 61 and each through hole 13h of the outer ring 13 extend parallel to the axis O and coincide with each other. A first bolt 62 is passed through the through hole 13h of the outer ring 13 and the female threaded hole 61f of the hub attachment 61 from one side in the direction of the axis O. 61, and the head of the first bolt 62 contacts the outer ring projecting portion 13g. As a result, the outer ring 13 is securely attached and fixed to the hub attachment 61 by the first bolts 62 .

The inner ring 12 is a cylindrical body longer than the outer ring 13 and is passed through the center hole of the outer ring 13 . A coupling portion 12 f is formed at one end portion of the inner ring 12 that protrudes from the outer ring 13 to the outside of the in-wheel motor drive device 10 in the direction of the axis O. As shown in FIG. The coupling portions 12f are protrusions provided at intervals in the circumferential direction, and constitute coupling portions for coaxially coupling the brake disc BD and wheels (not shown). The inner ring 12 is coupled with the road wheel of the wheel at the coupling portion 12f and rotates integrally with the wheel.

A plurality of rows of rolling elements 14 are arranged in the annular space between the inner ring 12 and the outer ring 13 . The outer peripheral surface of the central portion of the inner ring 12 in the direction of the axis O constitutes the inner raceway surface of the plurality of rolling elements 14 arranged in the first row. An inner raceway ring 12r is fitted to the outer periphery of the other end of the inner ring 12 in the direction of the axis O. As shown in FIG. The outer peripheral surface of the inner race 12r constitutes the inner raceway surface of the plurality of rolling elements 14 arranged in the second row. An inner peripheral surface of one end of the outer ring 13 in the direction of the axis O forms an outer raceway surface of the rolling elements 14 of the first row. The inner peripheral surface of the other end of the outer ring 13 in the direction of the axis O constitutes the outer raceway surface of the rolling elements 14 of the second row. A sealing material 16 is further interposed in the annular space between the inner ring 12 and the outer ring 13 . Sealing material 16 seals both ends of the annular space to prevent entry of dust and foreign matter. The output shaft 38 of the reduction section 31 is inserted and fitted into the center hole at the other end of the inner ring 12 in the direction of the axis O. As shown in FIG. Such fittings are spline fittings or serration fittings. In the case of spline fitting, relative rotation of the inner ring 12 and the output shaft 38 is prohibited, but there is a radial clearance between the inner ring 12 and the output shaft 38, which allows the inner ring 12 and the output shaft 38 to move slightly. It is allowed to tilt relatively at a folding angle of .

FIG. 3 shows the brake disc BD and the road wheel W of the wheel that are coupled with the inner wheel 12 of the in-wheel motor drive 10 . The in-wheel motor drive device 10 is accommodated in the inner hollow area of the road wheel W. As shown in FIG. However, the motor portion 21 may protrude from the inner hollow region of the road wheel W toward the inside in the vehicle width direction. The load wheel W is made of metal and is fitted with a rubber tire (not shown) on the outer diameter side.

The outer diameter of the inner ring 12 is maximized at the coupling portion 12f and minimized between the coupling portions 12f, 12f adjacent in the circumferential direction. The outer diameter of the outer ring 13 is maximized at the outer ring protrusion 13g. The outer diameter of the outer ring 13 is the smallest between the circumferentially adjacent outer ring protrusions 13g, 13g. The maximum outer diameters of the inner ring 12 and the outer ring 13 are smaller than the inner diameter of the road wheel W.

As shown in FIG. 3, the hub attachment 61 is formed with a protruding portion 61g that protrudes radially outward. A plurality of protrusions 61g are arranged at intervals in the circumferential direction. In this embodiment, the projecting portion 61g is tapered toward the outer diameter side, and the hub attachment 61 is star-shaped. With respect to the axis O, it is located on the outer diameter side of the outer ring projecting portion 13g. The diameter of the hub attachment 61 is thereby made larger than that of the outer ring 13 .

As shown in FIGS. 1 and 4, each projecting portion 61g is formed with a female threaded hole 61h extending parallel to the axis O. As shown in FIGS. A through hole 39h is formed in a front portion 39f located on the other side of the hub attachment 61 in the direction of the axis O. As shown in FIG. The through hole 39h and the female threaded hole 61h extend parallel to the axis O and coincide with each other. A female screw is formed in the female screw hole 61h. A second bolt 15 is passed through the through hole 39h from the other side in the direction of the axis O, and the tip of the second bolt 15 is screwed into the female thread of the through hole 61h. As a result, the hub attachment 61 is securely attached and fixed to the main body casing 39 by the second bolts 15 .

In FIG. 3, the second bolt 15 is omitted and a female threaded hole 61h passing through the hub attachment 61 is shown. As a modified example (not shown), some of the plurality of female screw holes 61h, 61h, . . . 61h and screwed into the internal thread of the through hole 39h. 61 f of female screw holes of this embodiment are arrange|positioned at circumferential direction equal intervals, and 61 h of female screw holes are also arrange|positioned at circumferential direction equal intervals. However, the circumferential position of the female screw hole 61f and the circumferential position of the female screw hole 61h are different. The female screw hole 61f is arranged on the inner diameter side of the projecting portion 61g.

In this embodiment, the fastening order of the first bolt 62 and the second bolt 15 is not particularly limited.

The wall thickness of the main body casing 39 is generally uniform, but the wall thickness of the front portion 39f is not uniform, and the portion where the through hole 39h is formed is formed thicker than the other portions. The thick portion 39g is arranged on the outer diameter side of the output gear 37, which will be described later.

As shown in FIG. 3, the hub attachment 61 has a star shape that is rotationally symmetrical about the axis O, with a projecting portion 61g having a maximum outer diameter and circumferentially adjacent projecting portions 61g, 61g having a minimum outer diameter. . The maximum outer diameter of the hub attachment 61 is smaller than the inner diameter of the road wheel W, and it is accommodated in the inner hollow region of the road wheel W together with the wheel hub bearing portion 11 (Fig. 4).

A plurality of first bolts 62 are arranged around the axis O at regular intervals in the circumferential direction. The second bolt 15 is also the same. The second bolt 15 is arranged on the outer diameter side of the first bolt 62 with respect to the axis O that is the center of the wheel hub bearing portion 11 . In FIG. 3, the addendum circle of the output gear 37 is represented by a dashed line. The first bolt 62 is arranged on the inner diameter side of the addendum circle of the output gear 37 and overlaps the output gear 37 when viewed in the axis O direction. On the other hand, the second bolt 15 is arranged on the outer diameter side of the addendum circle of the output gear 37 . According to the present embodiment, the fastening of the first bolt 62 is performed from the outside in the vehicle width direction, and the fastening of the second bolt 15 is performed from the inside in the vehicle width direction. is good.

As to the hub attachment 61, one end surface of the center region 61c in the direction of the axis O contacts the other end surface of the outer ring projecting portion 13g in the direction of the axis O. As shown in FIG. The other end surface of the central region 61c in the direction of the axis O faces or contacts the front portion 39f. A female threaded hole for screwing with the first bolt 62 is formed in the central region 61c. Therefore, the central region 61c is combined with the outer ring protrusion 13g. Further, the position of the projecting portion 61g in the direction of the axis O and the position of the outer ring projecting portion 13g in the direction of the axis O overlap.

The head of the first bolt 62 abuts on one end surface of the outer ring projecting portion 13g in the direction of the axis O. As shown in FIG. The head of the second bolt 15 abuts on one end surface of the projecting portion 61g in the direction of the axis O. As shown in FIG. The position of the head of the first bolt 62 in the direction of the axis O and the position of the head of the second bolt 15 in the direction of the axis O overlap.

The connecting portion 12f of the inner ring 12 and the outer ring projecting portion 13g are separated in the direction of the axis O, and the head portion of the first bolt 62 is arranged between the connecting portion 12f and the outer ring projecting portion 13g. A brake disc BD attached and fixed to the coupling portion 12f includes an outer diameter area and an inner diameter area bounded by the annular step BH. The inner diameter region is arranged on one side in the axis O direction, and the outer diameter region is arranged on the other side in the axis O direction. Both end surfaces of the outer diameter region serve as friction surfaces. The inner diameter region and the annular step BH constitute a hat portion. The hat section defines a cylindrical hollow region. The coupling portion 12f, the head portion of the first bolt 62, and the head portion of the second bolt 15 are housed in the hollow region of the hat portion because they are arranged on the inner diameter side of the annular step BH. Therefore, the position of the parts arranged in the inner hollow region of the hat portion in the direction of the axis O overlaps the position of the outer diameter region of the brake disc BD in the direction of the axis O, which contributes to shortening the dimension in the direction of the axis O.

The second bolt 15 surrounded by a two-dot chain line ellipse in FIG. Also, the second bolt 15 is made longer than the first bolt 62 . The position of the first bolt 62 in the direction of the axis O and the position of the second bolt 15 in the direction of the axis O overlap. Also, the position of the output gear 37 in the direction of the axis O and the position of the second bolt 15 in the direction of the axis O overlap.

The outer peripheral surface 13b of the other region in the direction of the axis O of the outer ring 13 is fitted to the inner peripheral surface of the opening 39p. An annular groove is formed in the outer peripheral surface 13b, and a seal member 19 is arranged in the annular groove. The sealing member 19 is, for example, an O-ring, and is in contact with the inner peripheral surface of the opening 39p over the entire circumference to seal the gap between the inner peripheral surface of the opening 39p and the outer peripheral surface 13b.

As shown in FIG. 1, the motor section 21 has a motor rotating shaft 22, a rotor 23, a stator 24, and a motor casing 29, which are arranged in this order from the axis M of the motor section 21 to the outer diameter side. The motor unit 21 is an inner rotor/outer stator type radial gap motor, but may be an electric motor of another type. For example, although not shown, the motor section 21 may be an axial gap motor. A motor casing 29 surrounds the outer circumference of the stator 24 . One end of the motor casing 29 in the direction of the axis M is coupled to the back portion 39b of the main body casing 39 . The other end of the motor casing 29 in the direction of the axis M is sealed with a plate-shaped motor casing cover 29v. The rear surface portion 39b is a casing wall portion that covers the other end of the reduction section 31 in the direction of the axis M (direction of the axis O) of the main body casing 39 .

The main body casing 39 and the motor casing 29 constitute a casing forming the outer shell of the in-wheel motor drive device 10 . In the following description, the body casing 39 and a part of the motor casing 29 are also simply referred to as casings.

The stator 24 includes a cylindrical stator core 25 and coils 26 wound around the stator core 25 . The stator core 25 is formed by laminating ring-shaped steel plates in the axis M direction.

Both ends of the motor rotating shaft 22 are rotatably supported by the rear portion 39b of the main body casing 39 and the motor casing cover 29v of the motor section 21 via rolling bearings 27 and 28 . Most of the motor rotating shaft 22 excluding one axial end 22 e is arranged inside the motor casing 29 . One axial end 22 e is arranged inside the main body casing 39 . That is, the motor rotating shaft 22 is housed in the casing of the in-wheel motor drive device 10 .

An axis M around which the motor rotating shaft 22 and the rotor 23 rotate extends parallel to the axis O of the wheel hub bearing portion 11 . That is, the motor portion 21 is offset away from the axis O of the wheel hub bearing portion 11 . For example, as shown in FIG. 2, the axis M of the motor section is offset from the axis O in the longitudinal direction of the vehicle, and more specifically, is arranged in front of the axis O of the vehicle.

The reduction unit 31 includes an input shaft 32 coaxially coupled to the motor rotation shaft 22 of the motor unit 21, an input gear 33 coaxially provided on the outer peripheral surface of the input shaft 32, a plurality of intermediate gears 34 and 36, and intermediate gears 34 and 36. An intermediate shaft 35 coupled to the centers of the gears 34 and 36, an output shaft 38 coupled to the inner ring 12 of the wheel hub bearing portion 11, an output gear 37 coaxially provided on the outer peripheral surface of the output shaft 38, and a plurality of these It has a main body casing 39 that houses the gears and the rotating shaft. The main body casing 39 forms an outer shell of the reduction section 31 and is therefore also referred to as a reduction section casing.

The input gear 33 is an external helical gear. The input shaft 32 has a hollow structure, and one axial end portion 22e of the motor rotating shaft 22 is inserted into the hollow hole 32h and spline-fitted (including serrations, the same shall apply hereinafter) so as not to rotate relative to each other. The input shaft 32 is rotatably supported on both end sides of the input gear 33 by a front portion 39f and a rear portion 39b of the body casing 39 via rolling bearings 32a and 32b.

An axis N, which is the center of rotation of the intermediate shaft 35 of the reduction section 31, extends parallel to the axis O. As shown in FIG. Both ends of the intermediate shaft 35 are rotatably supported by a front portion 39f and a rear portion 39b of the body casing 39 via rolling bearings 35a and 35b. A first intermediate gear 34 is coaxially provided at the other end of the intermediate shaft 35 in the direction of the axis N. As shown in FIG. A second intermediate gear 36 is coaxially provided in the center region of the intermediate shaft 35 in the direction of the axis N. As shown in FIG.

In addition, a concave portion is formed in the other end surface of the first intermediate gear 34 in the direction of the axis N, and the bearing 35b is housed in this concave portion. As a result, the position of the bearing 35b in the N direction of the axis line and the position of the tooth surface of the first intermediate gear 34 in the N direction of the axis line overlap, and the length of the intermediate shaft 35 is shortened.

The first intermediate gear 34 and the second intermediate gear 36 are helical gears with external teeth, and the diameter of the first intermediate gear 34 is larger than the diameter of the second intermediate gear 36 . The large-diameter first intermediate gear 34 is arranged on the other side of the second intermediate gear 36 in the direction of the axis N and meshes with the small-diameter input gear 33 . The small-diameter second intermediate gear 36 is arranged on one side of the first intermediate gear 34 in the direction of the axis N and meshes with the large-diameter output gear 37 .

The axis N of the intermediate shaft 35 is arranged above the axes O and M, as shown in FIG. Further, the axis N of the intermediate shaft 35 is disposed forward of the vehicle from the axis O and rearward of the axis M from the vehicle. The speed reduction unit 31 is a three-axis parallel shaft gear speed reducer having axes O, N, and M that are spaced apart in the vehicle front-rear direction and extend parallel to each other, and has a two-speed transmission.

Returning to FIG. 1, the output gear 37 is a helical gear with external teeth, and is provided coaxially with the central portion of the axis O of the output shaft 38 . The output shaft 38 extends along the axis O. As shown in FIG. One end of the output shaft 38 in the direction of the axis O is inserted into the center hole of the inner ring 12 and fitted so as not to rotate relative to each other. A center portion of the output shaft 38 in the direction of the axis O is rotatably supported by a front portion 39f of the main body casing 39 via a rolling bearing 38a on the outer diameter side of the outer peripheral surface 13b shown in FIG. The other end of the output shaft 38 in the direction of the axis O is rotatably supported by the back portion 39b of the main body casing 39 via a rolling bearing 38b.

As shown in FIG. 1, the speed reduction unit 31 includes a drive gear with a small diameter and a driven gear with a large diameter, that is, an input gear 33 and a first intermediate gear 34, and a second intermediate gear 36 and an output gear 37. , the rotation of the input shaft 32 is decelerated and transmitted to the output shaft 38 . A rotating element from the input shaft 32 to the output shaft 38 of the reduction section 31 constitutes a drive transmission path that transmits the rotation of the motor section 21 to the inner ring 12 .

The body casing 39 includes a tubular portion in addition to the front portion 39f and the rear portion 39b described above. The tubular portion covers the internal parts of the reduction section 31 so as to surround the axes O, N, M extending parallel to each other. The plate-like front portion 39f covers the internal parts of the reduction section 31 from one side in the axial direction and is coupled to one end of the cylindrical portion. The plate-shaped back surface portion 39b covers the internal parts of the speed reducing portion 31 from the other side in the axial direction and is coupled to the other end of the tubular portion. A rear portion 39 b of the main body casing 39 is coupled to the motor casing 29 and also serves as a partition wall that separates the internal space of the reduction section 31 and the internal space of the motor section 21 . The motor casing 29 is supported by the body casing 39 and protrudes from the body casing 39 to the other side in the axial direction.

The body casing 39 partitions the internal space of the reduction section 31 and accommodates all the rotating elements (rotating shaft and gears) of the reduction section 31 in the internal space. As shown in FIG. 2, the lower portion of the main body casing 39 serves as an oil reservoir 41 . The height position of the oil storage portion 41 overlaps the height position of the lower portion of the motor portion 21 . Lubricating oil for lubricating the motor portion 21 and the reduction portion 31 is stored in the oil reservoir portion 41 that occupies the lower portion of the internal space of the main body casing 39 .

The input shaft 32, the intermediate shaft 35, and the output shaft 38 are both supported by the rolling bearings described above. These rolling bearings 32a, 35a, 38a, 32b, 35b, 38b are radial bearings.

When electric power is supplied to the coil 26 described above from the outside of the in-wheel motor drive device 10 , the rotor 23 of the motor section 21 rotates, and rotation is output from the motor rotation shaft 22 to the reduction section 31 . The deceleration unit 31 decelerates the rotation input from the motor unit 21 to the input shaft 32 and outputs it from the output shaft 38 to the wheel hub bearing unit 11 . The inner ring 12 of the wheel hub bearing portion 11 rotates at the same rotational speed as the output shaft 38 to drive a wheel (road wheel W) (not shown) attached and fixed to the inner ring 12 .

FIG. 15 is a diagram showing the state of the in-wheel motor drive device of the present embodiment and its peripheral structure as viewed from the rear of the vehicle. An in-wheel motor drive device 10 arranged in an inner hollow area of the road wheel W is connected to a vehicle body (not shown) via a suspension device 100 . Suspension device 100 is, for example, a strut-type suspension device, and includes a lower arm 101 extending in the vehicle width direction, and a damper 102 arranged above lower arm 101 and extending in the vertical direction.

The lower arm 101 is rotatably connected to the vehicle body side member via cylindrical rubber bushes (not shown) at the vehicle width direction inner ends 101b and 101c. It can swing vertically with the outer end 101d as a free end. 101 d of vehicle width direction outside ends are connected with the lower part of the in-wheel motor drive device 10 via the ball joint 103. As shown in FIG. The in-wheel motor drive device 10 can freely change its direction with respect to the lower arm 101 .

The damper 102 extends vertically along the axis of a coil spring (not shown), and constitutes a strut of a strut-type suspension device together with the coil spring. The damper 102 and coil spring are also called a shock absorber. A lower end of the damper 102 is coupled with an upper portion of the in-wheel motor driving device 10 . The upper end (not shown) of the damper 102 is connected to the vehicle body side member.

FIG. 5 is a diagram showing a state in which the in-wheel motor drive device of the present embodiment is viewed from the outside in the vehicle width direction. FIG. 6 is a view showing the front part of the wheel hub bearing portion and the main body casing taken out from FIG. 5 . FIG. 7 is a view showing the structure shown in FIG. 6 as viewed from inside the in-wheel motor drive device, and corresponds to a state in which the front portion of the reduction section casing is viewed from the inside in the vehicle width direction.

A front portion 39f of the main body casing 39 is a one-member cover, and has an abutment surface 39v that is fixed in contact with the rear portion 39b. The abutment surface 39v is a flat surface extending along the outer circumference of the front portion 39f. The front portion 39f and the rear portion 39b are abutted against each other to define an internal space and form an outer shell of the speed reduction portion 31, and are therefore also called a speed reduction portion casing.

FIG. 8 is a perspective view of the structure shown in FIG. 6, showing wheel hub bearing 11 and front portion 39f. 9 is an exploded perspective view corresponding to FIG. 8. FIG. As shown in FIG. 9, a hub attachment 61 is arranged adjacent to the outside of the vehicle when viewed from the front portion 39f of the main body casing 39. As shown in FIG. A bolt 15 is passed from the inside of the vehicle through a through hole 39h formed in the front portion 39f. Therefore, the head portion 15b of the bolt 15 is arranged on the main body casing 39 side (vehicle inner side). Further, the shaft portion 15c of the bolt 15 is screwed into a female threaded hole 61h formed in the hub attachment 61. As shown in FIG.

According to this embodiment, since the female screw holes 61f and 61h are provided in the hub attachment 61 made of steel, the strength of the female screw holes 61f and 61h can be ensured, and the reliability of screw fastening is improved. If a female screw hole is provided in the aluminum or aluminum alloy front portion 39f, the strength of the female screw hole 61h cannot be ensured.

In this embodiment, the hub attachment 61 is fixed to the main body casing 39 with a plurality of bolts 15, specifically five bolts. Some of these bolt heads 15b, specifically three bolts 15a, 15a, 15a as shown in FIG. A circular recess 39j is formed in the inner wall surface of the front portion 39f. The circular recess 39j accommodates the head 15b of the bolt 15a.

FIG. 10 is a diagram showing a state in which a gear is attached to the structure shown in FIG. 7, viewed from the other direction of the axis O (inboard side). FIG. 11 is a cross-sectional view showing a portion connected by the bolt 15a, and represents a state in which the connection portion is cut along the AA cross section in FIG. 10 and the cut surface is viewed in the direction of the arrow. The bolt 15a is arranged at a position overlapping with the speed reducing portion 31 when viewed in the direction of the axis O. As shown in FIG. Referring to FIG. 11, the head 15b of each bolt 15a is covered with a lid member 17. As shown in FIG.

The lid member 17 includes a plate portion 17b, a cylindrical portion 17c erected on the plate portion 17b, and a seal portion 17d provided on the outer peripheral surface of the cylindrical portion 17c. A through hole 17h is formed in the plate portion 17b, and a bolt 18 is passed through the through hole 17h. The bolt 18 is screwed into a bottomed female screw hole 39k formed in the inner wall surface of the front portion 39f.

The cylindrical portion 17c fits into the circular recess 39j. The seal portion 17d contacts the inner peripheral surface of the circular recess 39j to seal the circular recess 39j. Thus, the bolt 15a is isolated from the inner space of the reduction section 31 by the cover member 17. As shown in FIG. The lubricating oil in the internal space passes through the through hole 39h through which the bolt 15a penetrates and is prevented from leaking out to the outside.

FIG. 12 is a cross-sectional view showing the wheel hub bearing portion of the present embodiment, specifically representing the wheel hub bearing portion of FIG. 4 . An oil pump 42 is provided at the other end of the output shaft 38 in the direction of the axis O. As shown in FIG. The oil pump 42 is driven by the output shaft 38 and supplies lubricating oil sucked from the oil storage portion 41 ( FIG. 2 ) to the inside of the motor portion 21 and the reduction portion 31 . Thereby, the lubricating oil circulates inside the in-wheel motor drive device 10 .

When the inner ring 12 and the output shaft 38 are spline-fitted, relative rotation between the inner ring 12 and the output shaft 38 is restricted, but there is a radial gap between the inner ring 12 and the output shaft 38 . Therefore, the output shaft 38 is allowed to incline with respect to the axis O. As shown in FIG. Grease is enclosed in such a gap.

A seal member 53 is provided on the other side of the spline fitting portion 51 in the direction of the axis O. As shown in FIG. The sealing material 53 is, for example, an O-ring, and seals an annular gap between the outer peripheral surface of the output shaft 38 and the inner peripheral surface of the inner ring 12 . As a result, the grease existing in the spline fitting portion 51 does not flow out into the reduction section 31 beyond the sealing member 53 . Also, the lubricating oil inside the deceleration portion 31 does not flow out to the spline fitting portion 51 beyond the sealing material 53 .

A position restricting member 52 is interposed between the seal member 53 and the spline fitting portion 51 and between the inner ring 12 and the output shaft 38 . The position regulating member 52 is a C-shaped member made of resin or metal. The position restricting member 52 prevents the sealing member 53 from moving in one direction of the axis O and being caught in the spline fitting portion 51 .

A position restricting member 54 is interposed between the inner ring 12 and the output shaft 38 on the other side in the direction of the axis O than the seal member 53 . The position regulating member 54 is a resin or metal member having a C-shaped cross section, and includes a cylindrical portion adjacent to the seal member 53 and one end face of the gear 37 in the direction of the axis O, which is formed at the other end of the cylindrical portion. and a flange portion that contacts the The position restricting member 54 prevents the sealing member 53 from slipping out in the other direction of the axis O from between the inner ring 12 and the output shaft 38 .

The position regulating members 52 and 54 are separate members, but as a modification, the position regulating members 52 and 54 may be one member coupled to each other.

FIG. 13 is a perspective view showing the in-wheel motor drive device of this embodiment. A wheel speed sensor 64 is fixed to the hub attachment 61 via a bracket 63 . The bracket 63 is mounted by a bolt 65 to a concave connecting seat 61d (FIG. 8). A female screw hole 61e into which the bolt 65 is screwed is formed in the connecting seat portion 61d. The connecting seat portion 61d of this embodiment is provided between the projecting portions 61g, 61g adjacent in the circumferential direction.

FIG. 14 is a cross-sectional view showing the mounting location of the wheel speed sensor. The wheel speed sensor 64 protrudes outward in the vehicle width direction (on one side in the direction of the axis O) from the bracket 63 , and its tip faces the detected portion 66 . The wheel speed sensor 64 of this embodiment protrudes parallel to the axis O. As shown in FIG. The detected portion 66 is a ring, and is provided in a concave hat portion defined by the inner diameter region of the brake disc BD and the annular step BH. The wheel speed sensor 64 is also arranged in the hat portion. Thus, the wheel speed sensor 64 is covered with the brake disc BD and protected from flying objects such as flying stones.

Bracket 63 supports the root of wheel speed sensor 64 . A base of the wheel speed sensor 64 is connected to one end of the sensor cable 67 . The sensor cable 67 extends toward the inside of the vehicle (the other in the direction of the axis O) from the bracket 63 and is connected to the antiskid brake system at the other end (not shown).

Anti-skid braking systems monitor the rotational speed of the wheels (ie brake discs BD) to prevent wheel lockup during braking.

The wheel speed sensor 64 of this embodiment is supported by the steel hub attachment 61 instead of being supported by the body casing 39 made of aluminum or aluminum alloy. Since the steel member undergoes less thermal deformation than the aluminum member, the influence of the detection accuracy on the wheel speed sensor 64 can be reduced.

Further, since the wheel speed sensor 64 is attached to the mating member in a posture parallel to the axle (axis O), there is little error in the attachment position. Furthermore, the detection accuracy can be improved by reducing the gap between the wheel speed sensor 64 and the detected portion 66 .

By the way, the in-wheel motor drive device 10 of the present embodiment has an inner ring 12, an outer ring 13, and a plurality of rolling elements 14 arranged in an annular gap between the inner ring 12 and the outer ring 13. The load wheel W is fixed to the inner ring 12. A wheel hub bearing portion 11 accommodated in an inner hollow region of the road wheel W, a motor portion 21 that outputs rotation, a reduction portion 31 that reduces the rotation output from the motor portion 21 and transmits it to the inner ring 12, and a road wheel W A hub attachment 61 that has a small diameter and is housed in the inner hollow region of the road wheel W is fixed to the outer ring 13 with a first bolt 62 and fixed to the body casing 39 of the reduction section 31 with a second bolt 15 .

According to this embodiment, the hub attachment 61 is fixed to the outer ring 13 by the first bolts 62 on one side, and is fixed to the main body casing 39 by the second bolts 15 on the other side. Not fixed. Therefore, no shaft load is input to the casing of the in-wheel motor drive device 10, and misalignment of the motor rotating shaft 22 and the intermediate shaft 35 (gear shaft) does not occur. In addition, since the outer ring 13 is fixed to the main body casing 39 via the hub attachment 61, the diameter of the hub attachment 61 can be adjusted without increasing the diameter of the outer ring 13 and the pitch diameter (PCD) of the wheel hub bearing portion 11. is increased, the second bolt 15 can be arranged on the outer diameter side of the outer ring 13 . Therefore, the existing wheel hub bearing can be used for the wheel hub bearing portion 11 to manufacture the in-wheel motor drive device 10, which is advantageous in terms of cost. Alternatively, the diameter of the wheel hub bearing portion 11 can be made smaller than before. Further, since the heads of the first bolt 62 and the second bolt 15 are oriented outward in the vehicle width direction, and the shaft portions are oriented inward in the vehicle width direction, the hub attachment 61 and the wheel hub bearing portion 11 are mounted on one side in the direction of the axis O. can be installed and removed from Therefore, the assembly work and the disassembly work of the in-wheel motor drive device can be performed from the outside in the vehicle width direction, and work efficiency is improved.

Further, since the second bolt 15 is arranged on the outer diameter side of the first bolt 62 with respect to the axis O of the wheel hub bearing portion 11, the maximum outer diameter of the outer ring 13 is smaller than the maximum outer diameter of the hub attachment 61. can do.

Further, as shown in FIG. 3 , the reduction section 31 has an output shaft 38 that is coaxially connected to the inner ring 12 and an output gear 37 that is provided coaxially with the output shaft 38 . As seen, the first bolt 62 is arranged so as to overlap the output gear 37 . Thereby, the maximum outer diameter of the outer ring 13 can be made smaller than the outer diameter of the output gear 37 .

In addition, since the second bolts 15 are arranged on the outer diameter side of the output gear 37 when viewed in the direction of the axis O of the wheel hub bearing portion 11, a large number of the second bolts 15 can be arranged spaced apart in the circumferential direction. . Further, since the through hole 39h through which the second bolt 15 penetrates is separated from the output gear 37 toward the outer diameter side, the thick portion 39g formed with the through hole 39h is made thicker than the other casing portions of the body casing 39. By increasing the thickness, the rigidity of the body casing 39 can be partially increased. Therefore, even if the axle load is transmitted to the second bolt 15, deformation of the main body casing 39 can be prevented.

Further, since the inner peripheral surface 61n of the hub attachment 61 is fitted with the cylindrical portion 39c of the main body casing 39 and positioned coaxially with the output shaft 38 of the reduction portion 31, the assembly work of the in-wheel motor drive device 10 The hub attachment 61 is naturally positioned with respect to the main body casing 39, improving assembly efficiency and assembly accuracy.

In addition, since the outer peripheral surface 13b of the outer ring 13 is fitted into the opening 39p of the main body casing 39 and positioned coaxially with the output shaft 38 of the speed reducing section 31, the outer ring 13 is positioned so as to be coaxial with the output shaft 38 of the in-wheel motor drive device 10 during the assembly work of the in-wheel motor drive device 10. It is naturally positioned with respect to the main body casing 39, and assembly efficiency and assembly accuracy are improved.

Although the embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the illustrated embodiments. Various modifications and variations can be made to the illustrated embodiment within the same scope as the present invention or within an equivalent scope.

INDUSTRIAL APPLICABILITY The in-wheel motor drive device according to the present invention is advantageously used in electric vehicles and hybrid vehicles.

10 in-wheel motor driving device, 11 wheel hub bearing,
12 inner ring, 12f coupling portion, 13 outer ring,
13b outer peripheral surface 13g outer ring protrusion 14 rolling element
15 second bolt 21 motor unit 22 motor rotating shaft
23 rotor, 24 stator, 29 motor casing,
31 reduction section, 32 input shaft, 33 input gear,
37 output gear 38 output shaft 39 body casing
39c cylindrical portion, 39f front portion, 39g thick portion,
39h through hole, 39p opening, 61 hub attachment,
61c central region, 61g protrusion, 61i tapered surface,
62 first bolt, BD brake disc, BH annular step,
M, N, O axis, W road wheel.

Claims (8)

a wheel hub bearing portion having an inner ring, an outer ring, and a plurality of rolling elements arranged in an annular gap between the inner ring and the outer ring, and arranged in an inner hollow region of a road wheel fixed to the inner ring;
a motor unit including a motor rotating shaft that drives the inner ring;
Rotating elements including an input shaft connected to the motor rotation shaft, an output shaft connected to the inner ring, and an output gear connected to the output shaft, decelerating the rotation of the input shaft and transmitting it to the output shaft a deceleration unit that
a casing that integrally includes a motor casing that houses the motor rotating shaft of the motor section and a reduction section casing that houses the rotating element of the reduction section;
a hub attachment that has a diameter smaller than that of the load wheel, is housed in the hollow space, is fixed to the outer ring with a first bolt, and is fixed to a front portion of the reduction section casing with a second bolt. motor drive. 2. The in-wheel motor drive device according to claim 1, wherein said second bolt is arranged radially outward of said first bolt with respect to the axis of said wheel hub bearing portion. 3. The in-wheel motor drive device according to claim 2, wherein said first bolt is arranged so as to overlap said output gear when viewed in the axial direction of said wheel hub bearing portion. 4. The in-wheel motor drive device according to claim 3, wherein said second bolt is arranged radially outward of said output gear when viewed in the axial direction of said wheel hub bearing portion. The in-wheel motor drive device according to any one of claims 1 to 4, wherein the hub attachment is fitted with the reduction section casing and positioned coaxially with the output shaft of the reduction section. The in-wheel motor drive device according to any one of claims 1 to 5, wherein the outer ring is fitted with the reduction section casing and positioned coaxially with the output shaft of the reduction section. further comprising a brake disc having a brake friction surface in an outer diameter region and having an inner diameter region fixed to the inner ring;
The in-wheel motor drive device according to any one of claims 1 to 6, wherein at least part of said first bolt and said second bolt is arranged radially inward of said brake friction surface. The inner diameter region is arranged on one side in the axial direction from the outer diameter region,
The brake disc further has an annular step connecting the inner diameter region and the outer diameter region,
The annular step and the inner diameter region form a hat portion that defines a cylindrical inner hollow region,
The in-wheel motor drive device according to claim 7, wherein at least part of said first bolt and said second bolt is arranged in said hollow region of said hat portion.

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