Inclined-type vehicle tire

Abstract

This inclined-type vehicle tire has: a carcass that straddles one bead core embedded in one bead part and the other bead core embedded in the other bead part; and a tread that is provided on the outside of the carcass in the tire radial direction and includes an elastic body, wherein the tread comprises at least an inner elastic body that is disposed on the vehicle mounting inner side of the tire equatorial plane, and an outer elastic body that is disposed on the vehicle mounting outer side of the inner elastic body, and the inner elastic body uses an elastic body having a slower wear progression rate than that of the outer elastic body.

Description

Tilting vehicle tires

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to tires for leaning vehicles.

[0002] A vehicle having three or more wheels and capable of turning while leaning like a two-wheeled vehicle has been disclosed (see Patent Document 1).

[0003] JP 2023-51041 A

[0004] An example of such a vehicle is the Lean Multi Wheel (LMW) vehicle, which has no restrictions on the maximum lean angle during turning, unlike motorcycles. Unlike motorcycles, an LMW vehicle maintains its lean angle through a balance between the center of gravity and centrifugal force, so the wheels on the outside and inside of a turn are approximately equal.

[0005] On the other hand, in the case of tilting mobility vehicles (hereinafter referred to as "tilting vehicles") that have been proposed recently, the maximum tilt angle when turning is limited to prevent tipping over when stationary, and when turning at high speed, an imbalance occurs between the ground contact conditions of the wheels on the inside and outside of the turn.

[0006] Specifically, a greater load acts on the inside shoulder of the wheel on the outside of a turn than on the outside shoulder of the wheel on the inside of a turn. As a result, the inside shoulder wears out faster than the outside shoulder. In other words, a difference in the amount of wear occurs between the inside shoulder and the outside shoulder. Moreover, because the shoulders only come into contact with the ground during turns, the difference in wear cannot be reduced during straight-line driving, and the difference in wear continues to widen as driving progresses.

[0007] The present disclosure aims to improve the wear resistance of the shoulder portion on the inside of the vehicle mounting surface.

[0008] The first aspect of the tire for a tilting vehicle includes a carcass spanning one bead core embedded in one bead portion and the other bead core embedded in the other bead portion, and a tread provided radially outward of the carcass and including an elastic body, wherein the tread includes at least an inner elastic body arranged on a vehicle-mounted inner side of the tire equatorial plane, and an outer elastic body arranged on a vehicle-mounted outer side of the inner elastic body, and the inner elastic body uses an elastic body whose wear rate is slower than that of the outer elastic body.

[0009] In the tilting vehicle tire according to the first aspect, at least the inner elastic body arranged on the vehicle-mounted inner side of the tire equatorial plane uses an elastic body whose wear growth rate is slower than that of the outer elastic body arranged on the vehicle-mounted outer side of the inner elastic body. In other words, the inner elastic body uses an elastic body having superior wear resistance to the outer elastic body.

[0010] Therefore, even if a greater load acts on the shoulder portion of the tread on the inside of the vehicle mounting side of the wheel on the outside of a turn than on the shoulder portion of the tread on the outside of the vehicle mounting side, there is less likely to be a difference in the amount of wear between the inside of the vehicle mounting side and the outside of the vehicle mounting side, and the wear resistance of the shoulder portion on the inside of the vehicle mounting side is improved.

[0011] In the tilting vehicle tire according to the second aspect, when the length of the contour of the tread surface in the tire axial cross section is L, the inner end portion in the tread width direction of the inner elastic body is located within a range of L / 8 from the tire equatorial plane toward the vehicle mounting inner side to L / 4 from the tire equatorial plane toward the vehicle mounting outer side in the case of the tilting vehicle tire according to the first aspect.

[0012] In the tilting vehicle tire according to the second aspect, the inner end portion in the tread width direction of the inner elastic body is located within a range of L / 8 from the tire equatorial plane toward the vehicle mounted inner side to L / 4 from the tire equatorial plane toward the vehicle mounted outer side, so that the wear resistance of the shoulder portion on the vehicle mounted inner side is improved, and the wear resistance in the vicinity of the tire equatorial plane can also be improved.

[0013] A tilting vehicle tire according to a third aspect is the tilting vehicle tire according to the second aspect, wherein an inner end portion in the tread width direction of the inner elastic body is located at L / 8 from the tire equatorial plane to the outer side mounted on the vehicle.

[0014] A tilting vehicle tire stands upright when the vehicle travels straight. Therefore, when the vehicle travels straight, the tilting vehicle tire mainly contacts the ground between 1 / 8 of the inner side mounted on the vehicle and 1 / 8 of the outer side mounted on the vehicle, in other words, the center region of the tread. In a tilting vehicle tire according to the third aspect, the inner end of the inner elastic body in the tread width direction is located at L / 8 from the tire equatorial plane to the outer side mounted on the vehicle. That is, since the inner elastic body having excellent wear resistance is arranged in the center region of the tread, the wear resistance of the center region of the tread that mainly contacts the ground when traveling straight can also be ensured.

[0015] According to the present disclosure, it is possible to improve the wear resistance of the shoulder portion on the inside of the vehicle mounting surface.

[0016] 1 is a front view showing a state of a tilting vehicle when turning. FIG. 2 is a cross-sectional view (cross-sectional view in the tire axial direction) showing a tire for a tilting vehicle according to an embodiment of the present invention.

[0017] Hereinafter, embodiments for carrying out the present disclosure will be described with reference to the drawings. Components indicated by the same reference numerals in each drawing are the same or similar components. Note that duplicated explanations and reference numerals may be omitted in the embodiments described below. Furthermore, all drawings used in the following description are schematic, and the dimensional relationships, ratios, etc. of each element shown in the drawings do not necessarily match those in reality. Furthermore, the dimensional relationships, ratios, etc. of each element between multiple drawings do not necessarily match.

[0018] In the drawings, the direction of arrow R indicates the tire radial direction, and the direction of arrow W indicates the tire width direction. The tire radial direction means a direction perpendicular to the tire rotation axis (not shown). The tire width direction means a direction parallel to the tire rotation axis. The tire width direction can also be referred to as the tire axial direction. Furthermore, "IN" indicates the inner side when mounted on a vehicle, and "OUT" indicates the outer side when mounted on a vehicle.

[0019] 1, the tilting vehicle 100 tilts when turning, but the maximum tilt angle during turning is limited to prevent the vehicle from tipping over when stationary, and the vehicle has the characteristic that, during high-speed turning, an imbalance occurs between the ground contact state of the wheel 12 on the inside of the turn (left side in FIG. 1) and the ground contact state of the wheel 14 on the outside of the turn (right side in FIG. 1). For this reason, the load F14 acting on the shoulder portion on the inside of the vehicle mounting of the wheel 14 on the outside of the turn is greater than the load F12 acting on the shoulder portion on the outside of the vehicle mounting of the wheel 12 on the inside of the turn. The shoulder portion will be described in detail later.

[0020] 2, the tire 10 for a tilting vehicle according to this embodiment is a so-called radial tire, and includes a bead core 18 embedded in one bead portion 16 and a carcass 20 that straddles the bead core 18 embedded in the other bead portion 16. The carcass 20 according to this embodiment is configured with two carcass plies as an example, but the number of carcass plies is not limited to two, and may be one, or three or more.

[0021] A spiral belt 22 is provided on the outer portion in the tire radial direction of the carcass 20, in other words, on the crown portion, and is configured by winding one or more parallel rubber-coated cords in a spiral shape. In the tire 10 for a tilting vehicle of this embodiment shown in Fig. 2, the spiral belt 22 is one layer, but it may be two or more layers.

[0022] A tread 24 is provided on the outer side of the spiral belt 22 in the tire radial direction, and a side rubber 26 is provided on the outer side of the carcass in the tire width direction.

[0023] 2 , the length of the contour of the tread surface in the tire axial cross section is defined as L, and the position along the contour from the tire equatorial plane CL at L / 8 is defined as ⅛ point T. In this embodiment, in the tread 24, the region axially outward from the ⅛ point T is called a shoulder region 24S, and the region between one ⅛ point T and the other ⅛ point T is called a center region 24C.

[0024] The tread 24 of this embodiment extends from the 1 / 8 point T on the outer side of the vehicle mounting to the tread end 24E on the outer side of the vehicle mounting. ＯＵＴThe outer tread rubber 28 is an example of an outer elastic body. The outer tread rubber 28 is formed of an outer tread rubber 28. The outer tread rubber 28 is formed ... elastic body. The outer tread rubber 28 is formed of an outer ＩＮ The inner tread rubber 30 is an example of an inner elastic body whose wear rate is slower than that of the outer tread rubber 28. In other words, the inner tread rubber 30 uses a rubber that is more wear resistant than the outer tread rubber 28. The inner end of the inner elastic body in the tread width direction is located at L / 8 from the tire equatorial plane to the outer side where it is fitted on the vehicle.

[0025] That is, the tread 24 of this embodiment has a center region 24C and a shoulder region 24S on the vehicle mounting inner side. ＩＮ The tread is formed of an inner tread rubber 30 which has better wear resistance than the outer tread rubber 28.

[0026] The abrasion resistance of the outer tread rubber 28 and the inner tread rubber 30 of the tread 24 can be tested using, for example, a Lambourn abrasion tester. Abrasion tests are conducted on two types of rubber using the Lambourn abrasion tester, and the rubber with superior abrasion resistance is used for the inner tread rubber 30, while the rubber with lower abrasion resistance compared to the rubber of the inner tread rubber 30 is used for the outer tread rubber 28. It is also possible to conduct a rubber abrasion test using an abrasion tester other than the Lambourn abrasion tester. Alternatively, a test tire with a different type of tread rubber may be manufactured as a prototype, and a vehicle fitted with the test tire may be driven on a road surface to conduct an abrasion test on the actual vehicle. Based on the results, the rubber used for the test tire with the least abrasion may be used for the inner tread rubber. As an example, a rubber with a higher hardness than the outer tread rubber 28 may be used for the inner tread rubber 30.

[0027] Although the tread 24 of this embodiment does not have any drainage grooves formed therein, drainage grooves may be formed therein as in a normal tire.

[0028] (Operations and Effects) The tire 10 for a tilting vehicle according to this embodiment is configured as described above, and its operations and effects will be described below.

[0029] As shown in FIG. 2, the tread 24 of the tire 10 for a tilting vehicle according to this embodiment is provided with an inner tread rubber 30 on the inner side mounted on the vehicle, which has superior wear resistance to the outer tread rubber 28 on the outer side mounted on the vehicle.

[0030] As a result, the shoulder portion 24S of the tread 24 on the inside of the wheel 14 on the outside of the turn ＩＮ The shoulder portion 24S of the tread 24 on the outer side of the vehicle ＯＵＴ Even if a load greater than 1 / 8 of the load acts on the tire, the difference in the amount of wear between the inside and outside of the vehicle mounting area is unlikely to occur in the area (shoulder area) axially outward from the 1 / 8 point T where the tire contacts the ground during cornering. ＩＮ The wear resistance of the material can be improved.

[0031] Furthermore, the tilting vehicle tire 10 stands upright when the vehicle travels straight. Therefore, when the vehicle travels straight, the center region 24C of the tread 24, which is located between the 1 / 8 point T on the inner side mounted on the vehicle and the 1 / 8 point T on the outer side mounted on the vehicle, mainly comes into contact with the ground. In the tilting vehicle tire 10 according to this embodiment, the inner tread rubber 30 having excellent wear resistance is arranged in the center region 24C of the tread 24, so that the wear resistance of the center region 24C of the tread 24, which mainly comes into contact with the ground when traveling straight, can also be ensured.

[0032] As described above, in the tire 10 for a tilting vehicle according to this embodiment, the entire tread 24 can be worn evenly.

[0033] [Other Embodiments] Although one example of an embodiment of the present disclosure has been described above, the embodiment of the present disclosure is not limited to the above, and it goes without saying that various modifications can be made without departing from the spirit of the present disclosure.

[0034] In the tire 10 for a leaning vehicle of the above embodiment, a known cross belt layer may be provided instead of the spiral belt 22. Furthermore, although the tire 10 for a leaning vehicle of the above embodiment is a radial tire, it may also be a bias tire.

[0035] In the tire 10 for a tilting vehicle of the above embodiment, a base rubber may be disposed between the spiral belt 22 and the outer tread rubber 28, and between the spiral belt 22 and the inner tread rubber 30. In other words, the tread 24 may have a two-layer structure (cap / base structure).

[0036] The position of the inner end of the inner tread rubber 30 in the tread width direction is not limited to 1 / 8 point T on the vehicle-mounted outer side from the tire equatorial plane CL, but may be located within a range of L / 8 toward the vehicle-mounted inner side from the tire equatorial plane to L / 4 toward the vehicle-mounted outer side from the tire equatorial plane. This makes it possible to improve the wear resistance near the tire equatorial plane CL compared to the vehicle-mounted outer side.

[0037] The outer tread rubber 28 and the inner tread rubber 30 may be made of a thermoplastic elastomer, which is a type of synthetic resin, instead of vulcanized rubber.

[0038] In addition, in this embodiment, two types of rubber are used: the outer tread rubber 28 on the outer side of the tire as mounted on the vehicle, and the inner tread rubber 30 which has better wear resistance than the outer tread rubber 28. However, the tire may be configured with three types of rubber, with a center tread rubber disposed between the inner tread rubber and the outer tread rubber. The center tread rubber can be disposed within a range of L / 8 from the tire equatorial plane toward the inner side of the tire as mounted on the vehicle to L / 4 from the tire equatorial plane toward the outer side of the tire as mounted on the vehicle.

[0039] [Contribution to the United Nations-led Sustainable Development Goals (SDGs)] The SDGs have been proposed to realize a sustainable society. It is believed that one embodiment of the present disclosure can be a technology that contributes to "No. 12: Responsible Consumption and Production" and "No. 13: Take concrete measures against climate change."

[0040] The disclosure of Japanese Patent Application No. 2024-122618, filed on July 29, 2024, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A tire for a tilting vehicle, comprising: a carcass spanning one bead core embedded in one bead portion and the other bead core embedded in the other bead portion; and a tread provided radially outward of the carcass and including an elastic body, wherein the tread comprises at least an inner elastic body arranged on the vehicle-mounted inner side of the tire equatorial plane, and an outer elastic body arranged on the vehicle-mounted outer side of the inner elastic body, and the inner elastic body uses an elastic body whose wear rate is slower than that of the outer elastic body.

2. A tilting vehicle tire according to claim 1, wherein, when the length of the contour of the tread surface in the tire axial cross section is L, the inner end of the inner elastic body in the tread width direction is located within a range of L / 8 from the tire equatorial plane toward the vehicle mounting inner side to L / 4 from the tire equatorial plane toward the vehicle mounting outer side.

3. A tire for a tilting vehicle according to claim 2, wherein an inner end portion in the tread width direction of the inner elastic body is located at a distance of L / 8 from the tire equatorial plane to the outer side when mounted on the vehicle.

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