JP2013018345A - Tire wheel assembly body for in-wheel motor, and pneumatic tire used for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve riding comfort and steering stability, while securing capacity of an accommodation space S.SOLUTION: A tire wheel assembly body 10 for an in-wheel motor includes a pneumatic tire 12 and a wheel 32. A carcass 24 is stretched over bead cores 20 at both ends via a tread part 14, and both ends of the carcass 24 are folded back at the bead core 20 so as to hold the bead core 20 and a bead filler 22 therebetween. The inner diameter of a bead section 18 located at the inner side of mounting on the vehicle is formed larger than that of a bead section 18 located at the outer side of mounting on the vehicle, to form a tire with a different diameter. When a tire cross sectional height at the inner side of mounting on the vehicle is defined as Hin, a tire cross sectional height at the outer side of mounting on the vehicle is defined as Hout, the height of the bead filler 22 at the inner side of mounting on the vehicle is defined as Fin, the height of the bead filler 22 at the outer side of mounting on the vehicle is Fout, and K is a coefficient, K.Hout/Hin=Fout/Fin, where 1.0≤K≤4.0 (expression 1) is satisfied.

Description

  The present invention relates to a tire / wheel assembly for an in-wheel motor and a pneumatic tire used therefor.

In a direct drive type electric vehicle, an open motor housing space is secured inside the mounting position inside the tire in the radial direction, an in-wheel motor is housed in the motor housing space, and the tire is directly driven to rotate by the in-wheel motor. .
In this case, it is conceivable to use a tire having a large outer diameter and a large inner diameter in order to secure a motor housing space.
On the other hand, in an electric vehicle, the volume of the battery is large, and the living space in the passenger compartment is already limited by this battery, so it is desirable to avoid further narrowing the living space in the passenger compartment by the tire storage space.
Conventionally, a tire has been proposed in which the inner diameter of the bead portion on the outer side of the vehicle is larger than the inner side of the vehicle, but in this tire, a large open motor housing space is secured on the inner side of the mounting position on the inner side in the radial direction of the tire. I can't.
As a result, in order to secure a large living space in the vehicle interior and to secure a motor accommodating space, the tire must be a low flat tire.

JP2001-88502

However, using a low flat tire deteriorates the riding comfort and handling stability of an electric vehicle.
The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide a tire for an in-wheel motor that can improve riding comfort and steering stability while ensuring the volume of the accommodation space inside the wheel. The object is to provide a wheel assembly and a pneumatic tire used therefor.

In order to achieve the above object, the present invention is a tire / wheel assembly for an in-wheel motor comprising a pneumatic tire and a wheel to which the pneumatic tire is assembled, and an in-wheel motor is disposed inside the wheel. The pneumatic tire includes a pair of bead portions each having a bead core and a bead filler, and a carcass that is bridged between the pair of bead portions through a tread portion and is folded at an end portion at the bead core and the bead filler. The bead portion located on the inner side of the vehicle mounting has a larger inner diameter than the bead portion positioned on the outer side of the vehicle mounting, and the wheel is connected to a rim on which a tire is mounted and the in-wheel motor. A disc that can be fitted to the bead portion located inside the vehicle. Is formed with an inner diameter larger than that of the rim to which the bead portion located on the outer side of the vehicle is fitted, and the disc is located on the outer side of the rim where the bead is mounted. In the radial inner side of the rim, an open storage space is formed on the inner side of the rim in which the in-wheel motor is accommodated, the tire cross-section height on the inner side of the vehicle mounting is Hin, and the tire cross-section height on the outer side of the vehicle mounting is When Hout is Hout, the bead filler height inside the vehicle is Fin, the bead filler height outside the vehicle is Fout, and K is a coefficient, the following equation 1 is satisfied.
K · Hout / Hin = Fout / Fin where K is 1.0 ≦ K ≦ 4.0 (Formula 1)
This is a tire / wheel assembly for an in-wheel motor.
The present invention also includes a pair of bead portions having a bead core and a bead filler, and a carcass that is bridged between the pair of bead portions through a tread portion and whose end portions are folded at the locations of the bead core and the bead filler. In the provided pneumatic tire, the bead portion located on the vehicle mounting inner side has a larger inner diameter than the bead portion positioned on the vehicle mounting outer side, and the tire cross-section height on the vehicle mounting inner side is Hin. When the outer tire section height is Hout, the bead filler height inside the vehicle is Fin, the bead filler height outside the vehicle is Fout, and K is a coefficient, the following equation 1 is satisfied.
K · Hout / Hin = Fout / Fin where K is 1.0 ≦ K ≦ 4.0 (Formula 1)
This is a pneumatic tire.

ADVANTAGE OF THE INVENTION According to this invention, while ensuring the volume of the accommodation space inside a wheel, the tire and wheel assembly for in-wheel motors which can improve riding comfort and steering stability, and the pneumatic tire used for it are obtained.
Therefore, it is possible to secure a large living space in the vehicle interior of the direct drive electric vehicle while improving ride comfort and driving stability.

It is sectional drawing of a tire and wheel assembly. It is sectional drawing of the pneumatic tire with which the wheel was mounted | worn. It is explanatory drawing of the test result of an Example and a comparative example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, a tire / wheel assembly 10 for an in-wheel motor to be assembled in a direct drive type electric vehicle includes a pneumatic tire 12 and a wheel 32 to which the pneumatic tire 12 is assembled. It consists of
The pneumatic tire 12 is a tire in which the mounting direction of the front and back of the tire when the vehicle is mounted is designated.
The pneumatic tire 12 includes a tread portion 14, sidewall portions 16 that extend inward in the tire radial direction from both ends of the tread portion 14, and bead portions 18 that are positioned at the end portions in the tire radial direction of the respective sidewall portions 16. ing.
Each bead portion 18 is provided with a bead core 20, and a bead filler 22 is provided on the outer side in the radial direction of the bead core 20 so as to be tapered outward in the tire radial direction.
Further, a carcass 24 is provided that passes through the tread portion 14 and is spanned between a pair of bead portions 18 and has an end portion wound up via a bead core 20. More specifically, the carcass 24 is passed over the bead core 20 at both ends through the tread portion 14, and both ends of the carcass 24 are folded back by the bead core 20 so as to sandwich the bead core 20 and the bead filler 22.
The bead portion 18 positioned on the vehicle mounting inner side has a larger inner diameter than the bead portion 18 positioned on the vehicle mounting outer side, and is a tire having a different diameter.
The tread portion 14 is provided with a belt layer 26 on the outer side in the tire radial direction of the carcass 24, and the tread portion 14 is located on the outermost side in the tire radial direction of the belt layer 26 and includes a cap rubber layer 28 that constitutes a ground contact surface. It is configured to include.

The wheel 32 includes a rim 34 on which the pneumatic tire 12 is mounted and a disk 36 connected to the in-wheel motor 50.
The rim 34 includes an inner rim flange portion 38in and an inner bead seat portion 40in positioned on the vehicle mounting inner side, and an outer rim flange portion 38out and an outer bead seat portion 40out positioned on the vehicle mounting outer side.
The inner rim flange portion 38in and the inner bead seat portion 40in are located on the outer side in the radial direction of the wheel 32 than the outer rim flange portion 38out and the outer bead seat portion 40out. That is, the location of the rim 34 to which the bead portion 18 located on the vehicle mounting inner side is fitted is formed with a larger inner diameter than the location of the rim 34 to which the bead portion 18 located on the outer side of the vehicle mounting is fitted.
As shown in FIG. 2, the bottom 42 extends from the outer bead seat portion 40out toward the vehicle mounting inner side, and the rising portion 44 extends from the end of the bottom portion 42 on the vehicle mounting inner side toward the outer side in the radial direction of the wheel 32. Is extended.
The upper portion of the rising portion 44 and the inner bead seat portion 40 in are connected by a cylindrical peripheral wall portion 46 extending along the axial direction of the wheel 32.
In the pneumatic tire 12, the bead portion 18 on the inner side of the vehicle is fitted to the inner rim flange portion 38in and the inner bead seat portion 40in, and the bead portion 18 on the outer side of the vehicle is attached to the outer rim flange portion 38out and the outer bead seat portion 40out. The wheel 32 is attached by being fitted.

The disc 36 is located on the vehicle mounting outer side of the wheel 32 and is connected to the inner peripheral portion of the bottom portion 42.
Therefore, on the inner side of the wheel 32, an open cylindrical storage space S is formed on the inner side in the radial direction of the rim 34 and on the inner side of the vehicle than the disk 36 toward the inner side of the vehicle.
The disk 36 has a spoke portion 52 that extends in the radial direction of the wheel 32 from the radially inner side of the bottom portion 42, and a hub portion 54 that is supported by the spoke portion 52.
The hub portion 54 has a hub hole 5402 through which the output shaft 5002 of the in-wheel motor 50 is inserted, and a bolt insertion hole provided around the hub hole 5402 for attaching the hub portion 54 to the hub portion 5004 on the output shaft 5002 side. 5404 is formed.
The in-wheel motor 50 is housed in the housing space S, the output shaft 5002 is inserted into the hub hole 5402, and the hub portions 54 and 5004 are fastened by the bolt 5406 inserted into the bolt insertion hole 5404, thereby being connected to the wheel 32. Has been.

As shown in FIG. 2, the pneumatic tire 12 according to the present embodiment has a tire cross-section height of Hin on the vehicle mounting inner side, a tire cross-section height of the vehicle mounting outer side of Hout, and a bead filler 22 height on the vehicle mounting inner side. When Fin, the height of the bead filler 22 on the outside of the vehicle is Fout, and K is a coefficient, the following formula 1 is satisfied.
K · Hout / Hin = Fout / Fin where K is 1.0 ≦ K ≦ 4.0 (Formula 1)
This is because when the coefficient K is smaller than 1, the tire rigidity on the outside of the vehicle is too low with respect to the tire rigidity on the inside of the vehicle, which is disadvantageous in improving ride comfort and handling stability. is there.
On the other hand, if the coefficient K is larger than 4, the tire rigidity on the outer side of the vehicle is too high relative to the tire rigidity on the inner side of the vehicle, which is disadvantageous in improving ride comfort and driving stability. is there.
Therefore, satisfying Expression 1 can improve ride comfort and handling stability while securing the volume of the accommodation space S inside the wheel.
Therefore, according to the present embodiment, it is possible to secure a large living space in the passenger compartment of the direct drive electric vehicle while improving ride comfort and driving stability.

Here, the tire cross-section height Hin on the inside of the vehicle is the inside of the vehicle mounted in a state where the tire is filled with the normal internal pressure specified in the JATMA standard, the ETRTO standard or the TRA standard and the normal load specified in the standard is applied. This is a dimension from the bead base line BLin to a position on the outer side in the tire radial direction of the tread portion 14, and corresponds to ½ of the difference between the tire outer diameter and the rim 34 diameter on the vehicle mounting inner side.
Further, the tire cross-section height Hout on the vehicle mounting outer side is a dimension from the bead base line BLout on the vehicle mounting outer side to the position on the outer side in the tire radial direction of the tread portion 14 in a state where a normal load is applied in the same manner as described above. This corresponds to ½ of the difference between the tire outer diameter and the rim 34 diameter on the outside of the vehicle.

Also, the bead filler 22 height Fin on the inner side of the vehicle mounting is from the bead base line BLin on the inner side of the vehicle mounting in a state where a normal load is applied to the position on the outer side in the tire radial direction of the bead filler 22 on the inner side of the vehicle mounting. It is the dimension.
Further, the bead filler 22 height Fout outside the vehicle is the same as described above, from the bead base line BLin outside the vehicle in a state where a normal load is applied, to the position outside the tire radial direction of the bead filler 22 outside the vehicle. It is the dimension.

  Moreover, it is preferable that the inner diameter of the bead portion 18 located on the inner side of the vehicle is formed with a dimension 2 inches or more larger than the inner diameter of the bead portion 18 located on the outer side of the vehicle. This is because it is advantageous in obtaining a great improvement in ride comfort.

Further, the ratio Fh of the height of the bead filler 22 obtained by dividing the height Fout of the bead filler 22 on the outside of the vehicle by the bead filler 22 height Fin on the inside of the vehicle should satisfy 1.5 ≦ Fh ≦ 5.0. Is preferred.
By doing so, it is advantageous in reducing the difference in rigidity between the vehicle mounting inner side and the vehicle mounting outer side, improving ride comfort and steering stability, and suppressing uneven wear.

Further, the hardness Hs of the rubber constituting the cap tread rubber layer may be uniform in the tire width direction, but if the inside of the vehicle is lower than the outside of the vehicle and the difference in hardness is in the range of 5 to 15. This is advantageous in reducing the difference in rigidity between the vehicle mounting inner side and the vehicle mounting outer side, improving the ride comfort and the handling stability, and suppressing uneven wear. Here, the hardness Hs is a durometer A hardness measured in an environment of 20 ° C. with a durometer type A based on JIS-K6253.
In this case, for example, in the cap tread rubber layer, the rubber hardness Hs of the portion located on the inner side of the vehicle with respect to the tire equator plane, and the hardness Hs of the rubber on the portion of the cap tread rubber layer positioned on the outer side of the vehicle with respect to the tire equator. It may be lowered within the range of 5 or more and 15 or less.

Example 1
A 1-inch different shaped tire corresponding to 215 / 35R19 on the inner side of the vehicle and 215 / 40R18 on the outer side of the vehicle is mounted on the inner rim flange portion 38in and the inner bead seat portion 40in on the inner side of the vehicle. The outer rim flange portion 38out and the outer bead seat portion 40out outside the vehicle are equivalent to the rim 34 of 18 × 71 / 2JJ, and are incorporated in the wheel 32 having the structure shown in FIGS. -It was set as the wheel assembly 10, and the magnitude | size of the accommodation space S inside the wheel 32 was evaluated.
(Examples 2 to 8)
A two-inch different shaped tire corresponding to 215 / 35R19 on the inner side of the vehicle and 215 / 45R17 on the outer side of the vehicle is mounted on the inner rim flange portion 38in and the inner bead seat portion 40in on the inner side of the vehicle. The outer rim flange portion 38out and the outer bead seat portion 40out outside the vehicle are equivalent to the rim 34 of 17 × 71 / 2JJ, and are incorporated in the wheel 32 having the structure shown in FIGS. -It was set as the wheel assembly 10, and the magnitude | size of the accommodation space S inside the wheel 32 was evaluated.
The tire and wheel assembly 10 of Examples 1 to 8 is mounted on four wheels of a four-wheel drive vehicle with a displacement of 2400 cc and travels 8000 km at a constant speed of 50 km / h with an air pressure of 220 kPa. And uneven wear were evaluated.

(Comparative Example 1)
A tire of 215 / 35R19 was incorporated into a rim 34 of 19 × 71 / 2JJ to form a tire / wheel assembly 10, and the size of the accommodation space S inside the wheel 32 was evaluated. Then, it was mounted on four wheels of a four-wheel drive vehicle with an air pressure of 220 kPa and a displacement of 2400 cc, and it traveled 8000 km at a constant speed of 50 km / h, and evaluated ride comfort, steering stability, and uneven wear.
(Comparative Example 2)
A tire of 215 / 45R17 was incorporated into a rim 34 of 17 × 71 / 2JJ to form a tire / wheel assembly 10, and the size of the accommodation space S inside the wheel 32 was evaluated. Then, it was mounted on four wheels of a four-wheel drive vehicle with an air pressure of 220 kPa and a displacement of 2400 cc, and it traveled 8000 km at a constant speed of 50 km / h, and evaluated ride comfort, steering stability, and uneven wear.

[Containment space S]
The accommodation space S is measured and indicated by an index value with the comparative example 1 as a reference (100). The larger this value, the larger the volume of the accommodation space S.
[Ride comfort]
This is a sensory evaluation of the tester, and is indicated by an index value based on Comparative Example 1 as a reference (100). The larger this value, the better the ride comfort.
[Steering stability]
This is a sensory evaluation of the tester, and is indicated by an index value with Comparative Example 1 as a reference (100). The larger this value, the better the steering stability.
[Uneven wear]
The uneven wear was visually observed and indicated by an index value with the comparative example 1 as a reference (100). The larger this value, the less the uneven wear.

As can be seen from FIG. 3, according to the first to eighth embodiments, the accommodation space S equivalent to the 19-inch wheel 32 can be secured, which is advantageous in improving riding comfort and driving stability and suppressing uneven wear. Become.
Further, as apparent from comparison between the first embodiment and the third to eighth embodiments, the inner diameter difference between the inner diameter of the bead portion 18 located inside the vehicle mounting and the bead portion 18 positioned outside the vehicle mounting is less than 2 inches. Is larger, it is advantageous for improving ride comfort and handling stability.
Further, as apparent from comparison between Example 2 and Examples 3 to 8, when the filler height ratio Fh (the ratio Fh of the height of the bead filler 22) is larger than 1.5, the ride comfort is obtained. And it is advantageous in improving the handling stability.
Further, as apparent from Examples 6 to 8, two kinds of rubbers constituting the cap tread rubber layer are provided with the tire equator plane as a boundary, and the hardness Hs of the rubber located on the vehicle mounting inner side than the tire equator plane is set. If the hardness Hs of the rubber located on the vehicle mounting outer side than the tire equator surface is lower than that of the tire, it is advantageous in improving ride comfort and driving stability and suppressing uneven wear. Further, as apparent from Example 7, when the hardness difference at that time is 10, it is most advantageous in improving ride comfort and handling stability and suppressing uneven wear.

  DESCRIPTION OF SYMBOLS 10 ... Tire and wheel assembly for in-wheel motor, 12 ... Pneumatic tire, 32 ... Wheel, 14 ... Tread part, 16 ... Side wall part, 18 ... Bead part, 20 ... Bead core, 22 …… Bead filler, 24 …… Carcass, 26 …… Belt layer, 28 …… Cap rubber layer, 32 …… Wheel, 34 …… Rim, 36 …… Disc, 50 …… In-wheel motor.

Claims (5)

A tire / wheel assembly for an in-wheel motor comprising a pneumatic tire and a wheel to which the pneumatic tire is assembled, and an in-wheel motor is disposed inside the wheel,
The pneumatic tire includes a pair of bead portions each having a bead core and a bead filler, and a carcass spanned between the pair of bead portions through a tread portion and folded at the ends of the bead core and the bead filler. Prepared,
The bead portion located on the vehicle mounting inner side is formed with a larger inner diameter than the bead portion positioned on the vehicle mounting outer side,
The wheel includes a rim on which a tire is mounted, and a disk that can be connected to the in-wheel motor,
The location of the rim to which the bead portion located on the inner side of the vehicle is fitted is formed with a larger inner diameter than the location of the rim to which the bead portion located on the outer side of the vehicle is fitted,
The disc is positioned on the outer side of the rim where the vehicle is mounted, and an open storage space is formed on the inner side of the rim where the in-wheel motor is stored inside the vehicle and on the inner side of the rim in the radial direction of the rim. And
The tire cross section height inside the vehicle mounting is Hin, the tire cross section height outside the vehicle mounting is Hout, the bead filler height inside the vehicle mounting is Fin, the bead filler height outside the vehicle mounting is Fout, and K is a coefficient. When the following equation 1 is satisfied,
K · Hout / Hin = Fout / Fin where K is 1.0 ≦ K ≦ 4.0 (Formula 1)
A tire / wheel assembly for an in-wheel motor. A pneumatic tire provided with a pair of bead portions each having a bead core and a bead filler, and a carcass that is spanned between the pair of bead portions through a tread portion and folded at an end at the bead core and the bead filler. Because
The bead portion located on the vehicle mounting inner side is formed with a larger inner diameter than the bead portion positioned on the vehicle mounting outer side,
The tire cross section height inside the vehicle mounting is Hin, the tire cross section height outside the vehicle mounting is Hout, the bead filler height inside the vehicle mounting is Fin, the bead filler height outside the vehicle mounting is Fout, and K is a coefficient. When the following equation 1 is satisfied,
K · Hout / Hin = Fout / Fin where K is 1.0 ≦ K ≦ 4.0 (Formula 1)
A pneumatic tire characterized by that. The inner diameter of the bead portion located on the inner side of the vehicle is formed with a dimension that is 2 inches or more larger than the inner diameter of the bead portion located on the outer side of the vehicle.
The pneumatic tire according to claim 2. The bead filler height ratio Fh obtained by dividing the bead filler height Fout on the outside of the vehicle by the bead filler height Fin on the inside of the vehicle satisfies the following formula 2.
1.5 ≦ Fh ≦ 5.0 (Formula 2)
The pneumatic tire according to claim 2 or 3, characterized in that. The cap tread rubber layer is located at the outermost position in the tire radial direction of the tread portion,
The hardness Hs of the rubber constituting the cap tread rubber layer is lower on the vehicle mounting inner side than on the vehicle mounting outer side, and the hardness difference is in the range of 5 to 15.
The pneumatic tire according to any one of claims 2 to 4, characterized in that:

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