Tire for inclined vehicle

Abstract

To improve wear resistance of a shoulder portion in an inner side in a state of being mounting to a vehicle.SOLUTION: A tire for an inclined vehicle 10 includes a tire case 18 connecting a pair of bead portions 16, and a tread 20 provided on the outer side in a tire radial direction of the tire case 18. A groove formed on a tread surface has groove depth in an inner side in a state of being mounting to a vehicle larger than groove depth in an outer side in the state of being mounting to the vehicle.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a tire for a tilting vehicle. [Background technology]

[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). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-51041 Summary of the Invention [Problem to be solved by the invention]

[0004] One such vehicle is the Lean Multi Wheel (LMW)® vehicle. Unlike motorcycles, LMW vehicles are not restricted in the maximum lean angle during turning, and the lean angle is maintained by balancing the center of gravity and centrifugal force, so the wheels on the outside and inside of the 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] An object of the present invention is to improve the wear resistance of the shoulder portion on the inside of the vehicle mounting surface. [Means for solving the problem]

[0008] The tilting vehicle tire according to the first aspect has a tire case spanning a pair of bead portions and a tread provided on the tire radial outer side of the tire case, and the groove depth on the inner side mounted on the vehicle is greater than the groove depth on the outer side mounted on the vehicle, formed on the tread surface.

[0009] In this tilting vehicle tire, the groove depth on the inside of the tread surface is greater than the groove depth on the outside of the tread surface, so even if the inside of the tread surface wears faster than the outside of the tread surface, the difference between the remaining groove depth on the inside of the tread surface and the remaining groove depth on the outside of the tread surface is prevented from widening.

[0010] In a second aspect, in the tilting vehicle tire according to the first aspect, when the length of the contour of the tread surface in the tire axial cross section is L and the position of L / 8 along the contour from the tire equatorial plane is the 1 / 8 point, the maximum groove depth on the vehicle mounting inner side is larger than the maximum groove depth on the vehicle mounting outer side at least within the contact area in the region axially outward from the 1 / 8 point.

[0011] In this tilting vehicle tire, the difference between the remaining grooves on the inside of the vehicle mounting surface and the remaining grooves on the outside of the vehicle mounting surface is prevented from widening, mainly in the area from the 1 / 8 point where the tire contacts the ground during cornering to the outside in the axial direction of the tire. [Effects of the Invention]

[0012] According to the present invention, the wear resistance of the shoulder portion on the inside of the vehicle mounting surface can be improved. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 2 is a front view schematically showing the state of the tilting vehicle when turning. [Figure 2] FIG. 1 is a development view showing a tread pattern of a tire for a tilting vehicle according to an embodiment of the present invention. [Figure 3] 3 is a cross-sectional view taken along the line 3-3 in FIG. 2, showing the tire for a tilting vehicle according to the present embodiment. [Figure 4] FIG. 10 is a diagram illustrating the difference in tread gauge in the tire axial direction between an example and a comparative example. [Figure 5] FIG. 10 is a diagram showing the difference in wear energy in the tire axial direction between an example and a comparative example due to differences in groove depth. [Figure 6] FIG. 10 is a diagram showing the difference in wear energy in the tire axial direction between an example and a comparative example due to differences in negative rate. [Figure 7] FIG. 10 is a diagram showing the difference in wear energy in the tire axial direction between an example and a comparative example due to differences in tread gauges. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention 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 descriptions 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 and ratios of elements shown in the drawings do not necessarily correspond to the actual ones. Furthermore, the dimensional relationships and ratios of elements between multiple drawings do not necessarily correspond to the actual ones.

[0015] In the drawings, the direction of arrow C indicates the tire circumferential direction, 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 the direction perpendicular to the tire rotation axis (not shown). The tire width direction means the direction parallel to the tire rotation axis (arrow X direction). The tire width direction can also be referred to as the tire axial direction. Additionally, "IN" indicates the inside direction when mounted on a vehicle, and "OUT" indicates the outside direction when mounted on a vehicle.

[0016] 1, the tilting vehicle 100 tilts when turning, but the maximum tilt angle when turning is limited to prevent tipping over when stationary, and has the characteristic that when turning at high speeds, an imbalance occurs between the ground contact state of the wheel 12 on the inside of the turn and the ground contact state of the wheel 14 on the outside of the turn. For this reason, the load F14 acting on the shoulder portion 26 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 26 on the outside of the vehicle mounting of the wheel 12 on the inside of the turn.

[0017] In FIG. 2, the tire 10 for a tilting vehicle according to this embodiment has a tire case 18 spanning a pair of bead portions 16, and a tread 20 provided on the outer side of the tire case 18 in the tire radial direction.

[0018] As shown in FIG. 2, grooves 22A, 22B, 24A, and 24B are formed on the surface of the tread 20. As shown in FIG. 3, the groove depth D on the vehicle-mounted inner side of the grooves 22A, 22B, 24A, and 24B formed on the tread surface is set to be larger than the groove depth on the vehicle-mounted outer side. In FIG. 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 at L / 8 from the tire equatorial plane is defined as 1 / 8 point T. The region axially outward from 1 / 8 point T is called the shoulder portion 26. As an example, in at least the contact zone of the region axially outward from 1 / 8 point T (shoulder portion 26), the maximum groove depth Dimax on the vehicle-mounted inner side is set to be larger than the maximum groove depth Domax on the vehicle-mounted outer side. Here, the groove depth D is measured in the normal direction to the tread surface. The contact zone is the area that contacts the ground at a certain inclination angle, and is indicated by an ellipse in FIG. 2, for example. When the left and right tires 10 are inclined at the same inclination angle, there are contact areas on the vehicle-mounted inner side and on the vehicle-mounted outer side. In comparing the two contact areas, it is sufficient that the maximum groove depth Dimax on the vehicle-mounted inner side is set larger than the maximum groove depth Domax on the vehicle-mounted outer side. The same applies to the thickness and negative ratio of the tread 20, which will be described later.

[0019] In FIG. 4, squares indicate the outer side of the example where the tire is mounted on a vehicle, circles indicate the inner side of the example where the tire is mounted on a vehicle, and crosses indicate the inner side of the comparative example where the tire is mounted on a vehicle. The thickness (tread gauge) of the tread 20 on the inner side of the tire where the tire is mounted on a vehicle may be greater than the thickness of the tread 20 on the outer side of the tire where the tire is mounted on a vehicle. As an example, in at least the contact area of ​​the region (shoulder portion 26) axially outward from the ⅛ point T, the thickness of the tread 20 on the inner side of the tire where the tire is mounted on a vehicle is greater than the thickness of the tread 20 on the outer side of the tire where the tire is mounted on a vehicle. In the example shown in FIG. 4, the maximum thickness Timax of the tread 20 is greater than the maximum thickness Tomax of the tread 20 on the outer side of the tire where the tire is mounted on a vehicle (Timax > Tomax). Note that the thickness distribution of the tread 20 is not limited to this and can be changed as desired.

[0020] In Figure 2, if the ratio of the area of ​​grooves 22A, 22B, 24A, 24B on the tread surface to the area of ​​the tread surface is defined as a negative ratio, the negative ratio on the vehicle-mounted inner side may be set to be smaller than the negative ratio on the vehicle-mounted outer side. As an example, in the region (shoulder portion 26) axially outward from 1 / 8 point T, the negative ratio on the vehicle-mounted inner side is smaller than the negative ratio on the vehicle-mounted outer side. In other words, the proportion of land areas without grooves on the tread surface is larger on the vehicle-mounted inner side than on the vehicle-mounted outer side, and the tread rigidity is higher.

[0021] In this embodiment, on the vehicle-mounted inner side, the groove 22A is provided on the side closer to the tire equatorial plane CL, and the groove 22B is provided on the side farther from the tire equatorial plane CL. The grooves 22A and 22B are provided alternately in the tire circumferential direction.

[0022] On the vehicle-mounted outer side, the groove 24A extends from the tread edge side past the 1 / 8 point T to near the tire equatorial plane CL. The groove 24B terminates from the tread edge side further outward in the tire width direction than the 1 / 8 point T. The positions of the ends of the grooves 24A and 24B on the tread edge side are equal in the tire width direction. The groove width is partially expanded at the end of the groove 24B on the tire equatorial plane CL side. The grooves 24A and 24B are alternately provided in the tire circumferential direction. The arrangement and shape of each groove are not limited to the example shown in the figure and can be changed as desired.

[0023] (action) This embodiment is configured as described above, and its operation will be described below. Referring to Figures 2 and 3, in the tilting vehicle tire 10 according to this embodiment, the groove depth D on the vehicle-mounted inner side is greater than the groove depth D on the vehicle-mounted outer side for the grooves 22A, 22B, 24A, and 24B formed on the tread surface. In particular, in at least the ground contact region in the region (shoulder portion 26) axially outward from the ⅛ point T, the maximum groove depth Dimax on the vehicle-mounted inner side is set greater than the maximum groove depth Domax on the vehicle-mounted outer side. Therefore, even if the wear on the vehicle-mounted inner side of the shoulder portion of the tread 20 is faster than the wear on the vehicle-mounted outer side, the difference between the remaining grooves 22A and 22B on the vehicle-mounted inner side and the remaining grooves 24A and 24B on the vehicle-mounted outer side is prevented from widening in the region (shoulder portion 26) axially outward from the ⅛ point T that mainly comes into contact with the ground during cornering. In this way, the difference between the remaining grooves 22A, 22B on the vehicle mounting inner side and the remaining grooves 24A, 24B on the vehicle mounting outer side is unlikely to widen.

[0024] Furthermore, the thickness of the tread 20 on the vehicle-mounted inner side is greater than the thickness of the tread 20 on the vehicle-mounted outer side. In particular, in at least the contact area in the region (shoulder portion 26) axially outward from ⅛ point T, the thickness of the tread 20 on the vehicle-mounted inner side is greater than the thickness of the tread 20 on the vehicle-mounted outer side (Timax > Tomax in FIG. 4). Therefore, even if the wear on the vehicle-mounted inner side of the shoulder portion of the tread 20 is faster than the wear on the vehicle-mounted outer side, the difference between the remaining thickness of the tread 20 on the vehicle-mounted inner side and the remaining thickness of the tread 20 on the vehicle-mounted outer side is prevented from widening in the region (shoulder portion 26) axially outward from ⅛ point T that contacts the tire mainly during cornering. In this way, a difference in the amount of wear is unlikely to occur between the vehicle-mounted inner side and the vehicle-mounted outer side.

[0025] Furthermore, in Figure 2, the negative ratio on the vehicle mounting inner side is smaller than the negative ratio on the vehicle mounting outer side. In particular, in the region (shoulder portion 26) from 1 / 8 point T to the axially outer side of the tire, the negative ratio on the vehicle mounting inner side is smaller than the negative ratio on the vehicle mounting outer side. Therefore, the tread rigidity on the vehicle mounting inner side is higher than the tread rigidity on the vehicle mounting outer side. As a result, even if a greater load acts on the shoulder portion 26 on the vehicle mounting inner side of the wheel 14 on the outer side of the turning than on the shoulder portion 26 on the vehicle mounting outer side, a difference in the amount of wear is unlikely to occur between the vehicle mounting inner side and the vehicle mounting outer side in the region (shoulder portion 26) from 1 / 8 point T to the axially outer side of the tire that mainly comes into contact with the ground during turning. In this way, a difference in the amount of wear is unlikely to occur between the vehicle mounting inner side and the vehicle mounting outer side of the tread 20.

[0026] Figure 5 shows the results of a simulation calculation of the difference in wear energy in the tire width direction for an example having a configuration in which the groove depth on the vehicle-mounted inner side is greater than the groove depth on the vehicle-mounted outer side, and a comparative example not having this configuration. Figure 6 shows the results of a simulation calculation of the difference in wear energy in the tire width direction for an example having a configuration in which the negative ratio on the vehicle-mounted inner side is smaller than the negative ratio on the vehicle-mounted outer side, and a comparative example not having this configuration. Figure 7 shows the results of a simulation calculation of the difference in wear energy in the tire width direction for an example having a configuration in which the thickness of the tread 20 on the vehicle-mounted inner side is greater than the thickness of the tread 20 on the vehicle-mounted outer side, and a comparative example not having this configuration. In both cases, it can be seen that the wear energy of the shoulder on the vehicle-mounted inner side is significantly reduced compared to the shoulder on the vehicle-mounted outer side.

[0027] In this way, according to this embodiment, it is possible to improve the wear resistance of the shoulder portion on the inside of the vehicle mounting surface.

[0028] [Other embodiments] The above describes one example of an embodiment of the present invention, but the embodiment of the present invention 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 invention.

[0029] [Contribution to the United Nations-led Sustainable Development Goals (SDGs)] The SDGs have been proposed to realize a sustainable society. One embodiment of the present invention is believed to be a technology that can contribute to goals such as "No. 12: Responsible Consumption and Production" and "No. 13: Take concrete measures to combat climate change." [Explanation of symbols]

[0030] 10...Tire for tilting vehicle, 12...Wheel on inside of turning, 14...Wheel on outside of turning, 16...Bead portion, 18...Tire case, 20...Tread, 22A...Groove, 22B...Groove, 24A...Groove, 24B...Groove, T...1 / 8 point

Claims

1. a tire case spanning the pair of bead portions; a tread provided on the tire radial direction outer side of the tire case, A tilting vehicle tire in which the groove depth on the inside of the tread surface is greater than the groove depth on the outside of the tread surface.

2. If the length of the contour of the tread surface in the tire axial cross section is L, and the position of L / 8 along the contour from the tire equatorial plane is defined as the 1 / 8 point, 2. The tilting vehicle tire according to claim 1, wherein the maximum groove depth on the vehicle mounting inner side is greater than the maximum groove depth on the vehicle mounting outer side at least within the contact area in the region axially outward from the 1 / 8 point.

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