Tire for leaning vehicle

Abstract

To improve wear resistance of a shoulder part on a vehicle mounting outer side.SOLUTION: The tire 10 for the inclined vehicle has a tire case 18 straddling a pair of bead parts 16 and a tread 20 provided on the outer side in the tire radial direction of the tire case 18, and a groove depth on the vehicle mounting outer side is larger than a groove depth on the vehicle mounting inner side in a groove formed on a tread surface.SELECTED DRAWING: Figure 4

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] Meanwhile, among the tilting mobility vehicles (hereinafter referred to as "tilting vehicles") recently proposed, city commuters, primarily used in urban areas, are subject to speed limits appropriate for urban driving. It is expected that such city commuters will frequently brake while tilted, for example, when turning at an intersection due to the presence of pedestrians on the crosswalk. When braking while tilted, the balance between the center of gravity and centrifugal force is disrupted, causing the center of gravity to shift toward the inside of the turn, resulting in an imbalance between the ground contact states of the inside wheel and the outside wheel. This results in a greater load acting on the outside shoulder of the inside wheel than on the inside shoulder of the outside wheel. Repeated occurrences of this condition result in faster wear on the outside shoulder than on the inside shoulder. In other words, a difference in the amount of wear occurs between the inside shoulder and the outside shoulder. Furthermore, because the shoulder portion only comes into contact with the ground when turning, the difference in the amount of wear cannot be reduced when driving straight, and the difference in the amount of wear continues to increase as the driving progresses.

[0006] An object of the present invention is to improve the wear resistance of the shoulder portion on the outer side of the vehicle mounting surface. [Means for solving the problem]

[0007] The first aspect of the tilting vehicle tire has a tire case spanning a pair of bead portions and a tread provided on the radially outer side of the tire case, and when the ratio of the area of ​​the grooves on the tread surface to the area of ​​the tread surface is defined as a negative ratio, the negative ratio on the outer side as mounted on the vehicle is smaller than the negative ratio on the inner side as mounted on the vehicle.

[0008] In this tilting vehicle tire, the negative ratio on the outer side of the vehicle is smaller than the negative ratio on the inner side of the vehicle, and the tread rigidity on the outer side of the vehicle is higher than the tread rigidity on the inner side of the vehicle. Therefore, even if a greater load acts on the shoulder portion on the outer side of the vehicle on the wheel on the inside of a turn than on the shoulder portion on the inner side of the vehicle, a difference in wear is unlikely to occur between the inner side of the vehicle and the outer side of the vehicle.

[0009] In the second aspect and the first aspect of the tilting vehicle tire, 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 the 1 / 8 point, then at least within the contact area in the region axially outward from the 1 / 8 point, the negative ratio on the vehicle-mounted outer side is smaller than the negative ratio on the vehicle-mounted inner side.

[0010] In this tilting vehicle tire, the difference in wear amount between the inside and outside of the vehicle mounting area is unlikely to occur mainly in the region from the 1 / 8 point where the tire contacts the ground during cornering to the outside in the tire axial direction. [Effects of the Invention]

[0011] According to the present invention, the wear resistance of the shoulder portion on the outer side of the vehicle mounting surface can be improved. [Brief explanation of the drawings]

[0012] [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] FIG. 2 is a diagram showing a negative ratio of the tread in the tire for a tilting vehicle according to the present embodiment. [Figure 4] 4 is a cross-sectional view taken along the line 4-4 in FIG. 2, showing the tire for a tilting vehicle according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] 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.

[0014] 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.

[0015] In FIG. 1, the tilting vehicle 100 is a city commuter vehicle (e.g., a personal or commercial ultra-compact mobility vehicle) primarily used in urban areas. According to the definition of the Ministry of Land, Infrastructure, Transport and Tourism, an ultra-compact mobility vehicle is a one- to two-seater vehicle that is more compact and maneuverable than an automobile, has excellent environmental performance, and is used for convenient local transportation. This type of tilting vehicle 100 tilts when turning, but the maximum tilt angle during turning is limited to prevent it from tipping over when stationary. Furthermore, when braking while the tilting vehicle 100 is in a tilted state, the balance between the center of gravity and centrifugal force is lost, causing the center of gravity to shift to the inside of the turn. This means that when braking while traveling in urban areas at relatively low speeds, an imbalance occurs between the ground contact states of the wheels 12 on the inside of the turn and the wheels 14 on the outside of the turn. Specifically, the load F12 acting on the shoulder portion 26 on the outer side of the vehicle of the wheel 12 on the inside of the turn is greater than the load F14 acting on the shoulder portion 26 on the inner side of the vehicle of the wheel 14 on the outside of the turn.

[0016] 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.

[0017] As shown in FIG. 2, grooves 22A, 22B, 24A, and 24B are formed on the surface of the tread 20. As shown in FIG. 4, the groove depth D on the vehicle-mounted outer 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 inner side. In FIG. 2, the length of the contour of the tread surface in the tire axial cross section is L, and the position along the contour that is L / 8 from the tire equatorial plane is set to 1 / 8 point T. The region axially outward from 1 / 8 point T is called the shoulder portion 26. Then, for example, in at least the contact zone of the region axially outward from 1 / 8 point T (shoulder portion 26), the maximum groove depth Domax on the vehicle-mounted outer side is set to be larger than the maximum groove depth Dimax on the vehicle-mounted inner side. For example, Domax - Dimax ≥ 0.3 mm. Here, the groove depth D is measured in the normal direction to the tread surface. The contact patch is an area that comes into contact with the ground at a certain inclination angle, and is shown 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 patches on the outer side of the vehicle and on the inner side of the vehicle. When comparing the two contact patches, it is sufficient that the maximum groove depth Domax on the outer side of the vehicle is set larger than the maximum groove depth Dimax on the inner side of the vehicle. The same applies to the negative ratio of the tread 20, which will be described later. 2 and 3, if the ratio of the area of ​​the grooves 22A, 22B, 24A, and 24B on the tread surface to the area of ​​the tread surface is defined as the negative ratio, the negative ratio on the vehicle-mounted outer side may be set to be smaller than the negative ratio on the vehicle-mounted inner side. For example, the negative ratio on the vehicle-mounted inner side - the negative ratio on the vehicle-mounted outer side ≥ 5%. As an example, in the region (shoulder portion 26) axially outward from the 1 / 8 point T, the negative ratio on the vehicle-mounted outer side is smaller than the negative ratio on the vehicle-mounted inner side. In other words, the proportion of land areas without grooves on the tread surface is larger on the vehicle-mounted outer side than on the vehicle-mounted inner side, and the tread rigidity is higher.

[0018] In this embodiment, on the vehicle-mounted outer 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.

[0019] On the vehicle mounting inner 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.

[0020] (action) This embodiment is configured as described above, and its operation will be described below. Referring to Figures 2 and 4, in the tilting vehicle tire 10 according to this embodiment, the groove depth D on the vehicle-mounted outer side of the grooves 22A, 22B, 24A, and 24B formed on the tread surface is greater than the groove depth D on the vehicle-mounted inner side. 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 Domax on the vehicle-mounted outer side is set greater than the maximum groove depth Dimax on the vehicle-mounted inner side. Therefore, even if the wear on the vehicle-mounted outer side of the shoulder portion of the tread 20 is faster than the wear on the vehicle-mounted inner side, the difference between the remaining grooves 22A and 22B on the vehicle-mounted outer side and the remaining grooves 24A and 24B on the vehicle-mounted inner 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 outer side and the remaining grooves 24A, 24B on the vehicle mounting inner side is unlikely to widen.

[0021] When braking while cornering, the larger groove depth D on the outer side of the vehicle reduces the pattern rigidity on the outer side of the vehicle, suppressing slippage with the road surface and improving wear resistance. Also, the inner side of the vehicle has a lower ground contact load than the outer side of the vehicle, which reduces cornering force, but the smaller groove depth D improves pattern rigidity, which compensates for the cornering force.

[0022] 2 and 3, the negative ratio on the vehicle-mounted outer side is smaller than the negative ratio on the vehicle-mounted inner side. In particular, in the region (shoulder portion 26) axially outward from 1 / 8 point T, the negative ratio on the vehicle-mounted outer side is smaller than the negative ratio on the vehicle-mounted inner side. Therefore, the tread rigidity on the vehicle-mounted outer side is higher than the tread rigidity on the vehicle-mounted inner side. As a result, even if a greater load acts on the shoulder portion 26 on the vehicle-mounted outer side of the wheel 12 on the inside of a turn than on the shoulder portion 26 on the vehicle-mounted inner side, a difference in the amount of wear is unlikely to occur between the vehicle-mounted outer side and the vehicle-mounted inner side in the region (shoulder portion 26) from 1 / 8 point T axially outward, which mainly comes into contact with the ground during a turn. In this way, a difference in the amount of wear is unlikely to occur between the vehicle-mounted outer side and the vehicle-mounted inner side of the tread 20.

[0023] When braking while turning, the large shear force of sliding generated by high load on the outside of the vehicle is suppressed by dispersing the ground pressure by lowering the negative ratio, improving resistance to uneven wear. Also, on the inside of the vehicle, cornering force on wet roads is reduced due to low load, but increasing the negative ratio concentrates the ground pressure, so cornering force on wet roads can be compensated for.

[0024] In this way, according to this embodiment, the wear resistance of the shoulder portion on the vehicle outer side can be improved.

[0025] [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.

[0026] [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]

[0027] 10...Tilting vehicle, 12...Wheel on the inside of turning, 14...Wheel on the 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, If the ratio of the area of ​​the groove on the tread surface to the area of ​​the tread surface is defined as a negative ratio, A tilting vehicle tire in which the negative rate on the outside of the vehicle is smaller than the negative rate on the inside of the vehicle.

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 from the tire equatorial plane along the contour is the 1 / 8 point, 2. The tilting vehicle tire according to claim 1, wherein the negative ratio on the outer side mounted on the vehicle is smaller than the negative ratio on the inner side mounted on the vehicle at least within the contact area in the region axially outward from the 1 / 8 point.

Images