Non-pneumatic tires

Abstract

To provide a non-pneumatic tire that allows for the intuitive detection of abnormalities using relatively inexpensive means. [Solution] The non-pneumatic tire 1 comprises a support structure 10 having an outer annular portion 30, an inner annular portion 20, and a plurality of spokes 40 arranged in the circumferential direction of the tire that connect the outer annular portion 30 and the inner annular portion 20; a tread fixed to the outer annular portion 30; and a connecting portion 71 that connects pairs of adjacent spokes 40 in the circumferential direction of the tire and has lower strength than the spokes 40.

Description

Technical Field

[0001] The present invention relates to a non-pneumatic tire.

Background Art

[0002] Conventionally, a non-pneumatic tire is known that includes a support structure that supports a load from a vehicle and contains a resin, and a tread that is located radially outside the support structure and extends along the tire circumferential direction. It is difficult to detect an abnormality (for example, damage to a connecting portion) of a non-pneumatic tire at an early stage, and this is an existing technical problem. Conventionally, for example, an abnormality is detected using a sensor attached to a non-pneumatic tire (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the conventional abnormality and failure detection method, the cost of the sensor is incurred. In addition, it is difficult for the user to intuitively grasp an abnormality.

[0005] An object of the present invention is to provide a non-pneumatic tire that enables an abnormality to be intuitively grasped by relatively inexpensive means.

Means for Solving the Problems

[0006] A non-pneumatic tire according to the present invention includes a support structure having an outer annular portion, an inner annular portion attached to the wheel, and a plurality of connecting portions arranged in the tire circumferential direction that connect the outer annular portion and the inner annular portion, a tread fixed to the outer annular portion, and a connecting portion that connects a pair of adjacent connecting portions in the tire circumferential direction among the plurality of connecting portions and has a lower strength than the connecting portion. [Effects of the Invention]

[0007] According to the present invention, a non-pneumatic tire can be obtained that allows for the intuitive detection of abnormalities by relatively inexpensive means. [Brief explanation of the drawing]

[0008] [Figure 1] This is a side view showing a non-pneumatic tire according to the first embodiment of the present invention. [Figure 2] This is a cross-sectional view taken along line II-II in Figure 1. [Figure 3] Figure 2 is a perspective view of a portion of a non-pneumatic tire, seen from an oblique angle. [Figure 4] This is a magnified view of a portion of Figure 1, showing the anomaly detection structure. [Figure 5] Figure 2 is a cross-sectional view of the VV section, showing the first spoke, the second spoke, and the anomaly detection structure. [Figure 6] This diagram schematically shows the first spoke, the second spoke, and the anomaly detection structure as viewed in the tire width direction (before fracture). [Figure 7] This diagram schematically shows the first spoke, the second spoke, and the anomaly detection structure as viewed in the tire width direction (moment of fracture). [Figure 8] This diagram schematically shows the first spoke, the second spoke, and the anomaly detection structure as viewed in the tire width direction (after fracture). [Figure 9] This graph shows the change in load with respect to displacement at the connection point between the spoke and the anomaly detection structure. [Figure 10] This is a cross-sectional view showing the first spoke, the second spoke, and the anomaly detection structure in the second embodiment. [Figure 11] In the third embodiment, this diagram schematically shows the first spoke, the second spoke, and the abnormality detection structure as viewed in the tire width direction (before breakage). [Figure 12]In the fourth embodiment, this is a schematic diagram (before breakage) showing the first spoke, the second spoke, and the abnormality detection structure as viewed in the tire width direction. [Modes for carrying out the invention]

[0009] (First embodiment) (Basic structure of non-pneumatic tires) A non-pneumatic tire 1 of the first embodiment of the present invention will be described using Figures 1 to 3. Figure 1 is a side view showing a non-pneumatic tire according to one embodiment of the present invention. Figure 2 is a cross-sectional view taken along line II-II of Figure 1. Figure 3 is a partial perspective view of the non-pneumatic tire, taken from an oblique angle from the portion shown in Figure 2. In the following description, the dimensional ratios in the drawings do not necessarily match the actual dimensional ratios, and the dimensional ratios between the drawings do not necessarily match either.

[0010] The non-pneumatic tire 1 comprises a support structure 10 and a tread 50. Here, the support structure 10 supports the load from the vehicle. The tread 50 is located outside the support structure 10 in the tire radial direction X and extends along the tire circumferential direction C. The support structure 10 also comprises an inner annular portion 20, an outer annular portion 30 arranged coaxially with the inner annular portion 20 on the outside of the inner annular portion 20 in the tire radial direction X, and a plurality of spokes 40 (connecting portions) that connect the inner annular portion 20 and the outer annular portion 30 and are arranged along the tire circumferential direction C.

[0011] (Detailed structure of non-pneumatic tires) Figure 1 is a side view of the non-pneumatic tire 1, viewed from a direction parallel to the tire rotation axis (tire meridian), that is, along the direction of the front and back of the paper in Figure 1. The non-pneumatic tire 1 shown in Figure 1 is in an unloaded state.

[0012] In FIGS. 1 and 3, C indicates the tire circumferential direction. In FIGS. 1 to 3, X indicates the tire radial direction. In FIGS. 2 to 3, Y indicates the tire width direction. In FIG. 1, the tire width direction Y is the front and back direction of the paper surface. In FIG. 2, E indicates the tire equatorial plane. In FIG. 2, the tire circumferential direction C is the front and back direction of the paper surface.

[0013] The tire circumferential direction C is the direction around the tire rotation axis and is the same as the direction in which the non-pneumatic tire 1 rotates. The tire radial direction X is the direction perpendicular to the tire rotation axis. The tire width direction Y is the direction parallel to the tire rotation axis. In FIGS. 2 to 3, one side of the tire width direction Y is shown as Y1, and the other side of the tire width direction Y is shown as Y2. The tire equatorial plane E shown in FIG. 2 is a plane perpendicular to the tire rotation axis and is located at the center of the tire width direction Y.

[0014] The inner annular portion 20 is an annular portion along the tire circumferential direction C that constitutes the inner peripheral portion of the non-pneumatic tire 1. The thickness and width of the inner annular portion 20 are set to be constant in order to improve uniformity. A tire wheel (not shown) is disposed in the space on the inner peripheral side of the inner annular portion 20. The inner peripheral portion of the inner annular portion 20 is fitted and mounted on the outer peripheral portion of the rim of the tire wheel. When the inner annular portion 20 is mounted on the rim, the non-pneumatic tire 1 is mounted on the tire wheel.

[0015] The inner annular portion 20 transmits the rotation of the tire wheel to the spokes 40 and the outer annular portion 30.

[0016] The outer annular portion 30 is an annular portion along the tire circumferential direction C that constitutes the outer peripheral portion of the non-pneumatic tire 1. The outer annular portion 30 is disposed concentrically with the inner annular portion 20 on the outer peripheral side of the inner annular portion 20.

[0017] The outer annular portion 30 transmits the rotation of the inner annular portion 20 and the spokes 40 to the road surface via the tread 50.

[0018] Multiple spokes 40 connect the inner annular portion 20 and the outer annular portion 30. The inner annular portion 20 and the outer annular portion 30, connected by the multiple spokes 40, are arranged concentrically with respect to each other. Each of the multiple spokes 40 is arranged independently along the tire circumferential direction C. As shown in Figure 1, when the non-pneumatic tire 1 is unloaded, the multiple spokes 40 extend linearly in the radial direction, approximately parallel to the tire radial direction X, when viewed from the side.

[0019] As shown in Figures 2 and 3, the spokes 40 of this embodiment include a plurality of first spokes 41 and a plurality of second spokes 42. The extending direction of both the first spokes 41 and the second spokes 42 is not parallel to the tire radial direction X when viewed along the tire circumferential direction C. The first spokes 41 are inclined toward one side in the tire axial direction, i.e., the tire width direction Y. The second spokes 42 are inclined toward the opposite side from the first spokes 41. The first spokes 41 and the second spokes 42 are arranged alternately in the tire circumferential direction C.

[0020] More specifically, as shown in Figures 2 and 3, the first spoke 41 extends inclined from the Y1 side, which is one side of the outer annular portion 30 in the tire width direction Y, toward the Y2 side, which is the other side of the inner annular portion 20 in the tire width direction Y. The second spoke 42 extends inclined from the Y2 side, which is the other side of the outer annular portion 30 in the tire width direction Y, toward the Y1 side, which is one side of the inner annular portion 20 in the tire width direction Y.

[0021] The inclination angles of the first spoke 41 and the second spoke 42 are the same. Therefore, when viewed from a direction along the tire circumferential direction C, the first spoke 41 and the second spoke 42 adjacent to each other in the tire circumferential direction C are arranged in a roughly X shape.

[0022] The tread 50 is provided on the outer circumferential surface of the outer annular portion 30 and constitutes the outermost periphery of the non-pneumatic tire 1. The tread 50 has a tread surface 51 on its outer circumferential surface that contacts the road surface. The tread surface 51 of the tread 50 is provided with a tread pattern formed by multiple grooves and land areas, similar to conventional pneumatic tires.

[0023] The support structure 10, which includes the inner annular portion 20, the outer annular portion 30, and the plurality of spokes 40 described above, is made of resin. The resin that constitutes the support structure 10 is not particularly limited, but examples include thermosetting resins and thermosetting elastomers such as urethane resin, epoxy resin, and phenolic resin, and thermoplastic resins and thermoplastic elastomers such as polyethylene, polyurethane, polyester, and polyamide. It is preferable that the resin that constitutes the support structure 10 contains one or more additives selected from the group consisting of ultraviolet blocking agents, ultraviolet absorbing agents, antioxidants, and light stabilizers in order to ensure the durability of the support structure 10.

[0024] (Anomaly detection structure) The non-pneumatic tire 1 has an abnormality detection structure 70. The abnormality detection structure 70 is a mechanism for detecting abnormalities in the spokes 40. An abnormality in the spokes 40 refers to a failure that occurs in the spokes 40 when, for example, a spoke distortion occurs in response to input from the vehicle that reduces the function of the non-pneumatic tire 1.

[0025] The anomaly detection structure 70 will be explained using Figures 4 and 5. Figure 4 is a partially enlarged view of Figure 1, showing the anomaly detection structure. Figure 5 is a cross-sectional view of the first spoke, the second spoke, and the anomaly detection structure.

[0026] The anomaly detection structure 70 has a connecting part 71 as its main structure. The connecting part 71 connects a pair of spokes 40 that are adjacent in the circumferential direction of the tire (i.e., the first spoke 41 and the second spoke 42) from among the multiple spokes 40. The anomaly detection structure 70 is weaker than each spoke 40. When a spoke strain occurs in response to input from the vehicle that reduces the function of the non-pneumatic tire 1, it is determined that an anomaly has occurred in the spoke. Therefore, the connecting part 71 is designed to break when such a large input occurs. When a break occurs, the broken parts of the connecting part 71 come into contact with each other while driving, producing a knocking sound. The knocking sound is, for example, a rubbing sound produced by the broken parts of the connecting part 71 repeatedly separating and coming together. This allows the driver to detect a malfunction while driving. In particular, the driver can intuitively judge the anomaly by hearing a knocking sound that is different from the normal driving sound. In summary, since the abnormality of the spokes 40 can be conveyed to the driver through the physical phenomenon described above, the cost is reduced compared to conventional anomaly detection structures that use sensors.

[0027] The driver can ultimately confirm the failure of the spoke 40 by looking at the broken connection point 71. In this way, the driver can intuitively determine the abnormality of the spoke 40 simply by looking at whether the connection point 71 is broken or not.

[0028] The connecting portion 71 is provided between all the spokes 40. This allows the driver to accurately determine which spoke 40 has malfunctioned. For example, if one connecting portion 71 is broken, it can be determined that a malfunction has occurred in one or both of the spokes 40 on that side. Furthermore, for example, if multiple connecting portions 71 aligned in the circumferential direction C of the tire are broken, it can be determined that a malfunction has occurred in the spokes 40 to which those multiple connecting portions 71 are connected.

[0029] (German construction of the connection point) The specific structure of the connection part 71 will be described.

[0030] The connecting portion 71 connects the intermediate portions 41A and 42B of the first spoke 41 and the second spoke 42, respectively. More specifically, the connecting portion 71 connects the intersecting portions 41a and 42a of the first spoke 41 and the second spoke 42, which intersect in a roughly X-shape when viewed from a direction along the tire circumferential direction C. Even more specifically, the connecting portion 71 extends between the opposing surfaces of the intersecting portions 41a and 42a. In other words, the connecting portion 71 connects the first spoke 41 and the second spoke in the tire circumferential direction. Note that the opposing surfaces of the intersecting portions 41a and 41b are flat surfaces.

[0031] The connecting portion 71 is a thin film. More specifically, the connecting portion 71 is a thin member in the tire radial direction. The connecting portion 71 is positioned along the tire equatorial plane E between the intersecting portions 41a and 42a and is formed over the entire tire radial direction X of the intersecting portions 41a and 42a. More specifically, the connecting portion 71 is integrally molded with the intersecting portions 41a and 42a.

[0032] The thickness t1 of the connecting portion 71 (Figure 5) is, for example, 0.01 mm or more and 20 mm or less.

[0033] The length L1 (Figure 6) of the connecting portion 71 in the tire circumferential direction C is, for example, 0.01 mm or more and 200 mm or less.

[0034] The length L2 (Figure 6) of the connecting portion 71 in the tire radial direction X is, for example, 0.01 mm or more and 200 mm or less.

[0035] The material of the connecting portion 71 is preferably the same resin as that of the support structure 10.

[0036] The thickness t1 of the connecting portion 71 in the tire width direction Y is thinner than the thickness t2 of the spoke 40 in the tire circumferential direction C. The length L2 of the connecting portion 71 in the tire radial direction X is shorter than the length of the spoke 40 in the tire radial direction. As a result, the strength of the connecting portion 71 is reliably lower than the strength of the spoke 40.

[0037] The connecting portion 71 is formed simultaneously when the support structure 10 is molded, for example, by a casting method. Specifically, the connecting portion 71 is formed in a thin film form by a divided mold that is divided in the tire width direction Y when the support structure 10 is molded. More specifically, the connecting portion 71 is formed by a newly created gap at the abutting surface along the partition line PL (a linear portion along the joint between the upper and lower molds of the divided mold, see Figure 5) of the first spoke 41 and the second spoke 42.

[0038] Since the connecting portion 71 is a thin film, it has little effect on the initial tire rigidity, and therefore the design of the non-pneumatic tire 1 is easy even with the connecting portion 71 provided.

[0039] (Operation of the connection part of the anomaly detection structure) The operation of the connection part 71 will be explained using Figures 6 to 8. Figure 6 is a schematic diagram showing the first spoke, the second spoke, and the abnormality detection structure as viewed in the tire diameter direction (before breakage). Figure 7 is a schematic diagram showing the first spoke, the second spoke, and the abnormality detection structure (moment of breakage). Figure 8 is a schematic diagram showing the first spoke, the second spoke, and the abnormality detection structure (after breakage).

[0040] When a large force is applied to the first spoke 41 and the second spoke 42 from the state shown in Figure 6, the connecting portion 71 breaks, separating into a first fractured portion 71a and a second fractured portion 71b, as shown in Figure 7. As a result, as shown in Figure 8, the fracture surfaces of the first fractured portion 71a and the second fractured portion 71b become close together or in contact with each other.

[0041] Subsequently, as the vehicle is in motion, the connection portion 71 repeatedly comes into contact with the first fractured portion 71a and the second fractured portion 71b, producing a knocking sound.

[0042] (Setting the strength of the connection point) The setting of the strength of the connection part 71 will be explained using Figure 9. Figure 9 is a graph showing the change in load with respect to the displacement of the connection part between the spoke and the anomaly detection structure.

[0043] In Figure 9, the solid line represents the displacement-load characteristics of the spoke 40, and the dashed line represents the displacement-load characteristics of the connector 71. Load A is a predetermined value where the displacement of the spoke 40 is near the limit of the linear region. For example, a load below A is the region where the function of the spoke 40 does not deteriorate (linear region). The connector 71 is set to a strength that causes it to break when it reaches load A. That is, the connector 71 has a strength that causes it to break before the spoke 40 breaks, when the displacement of the spoke 40 reaches a predetermined value near the limit of the linear region. This ensures that the connector 71 breaks before the spoke 40 breaks.

[0044] (Second embodiment) In the first embodiment, the thickness t1 of the connecting portion 71 is constant over the tire circumferential direction C, but the ease of breakage may be adjusted by partially changing the thickness. As such an embodiment, the second embodiment will be described with reference to Figure 10. Figure 10 is a cross-sectional view of the connecting portion between the first spoke, the second spoke, and the abnormality detection structure in the second embodiment. Note that the basic structure of the second embodiment is the same as that of the first embodiment, so only the differences will be described below.

[0045] The connection portion 71A of the abnormality detection structure 70A is a thin film, similar to the first embodiment. The thickness of the connection portion 71A1 and 71A2 at both ends in the tire circumferential direction (Y in the tire width direction) is thinner (smaller in dimension) than the thickness of the central portion 71A3 in the tire circumferential direction. As a modification, the thickness of the central portion in the tire circumferential direction may be thinner than the thickness of both ends in the tire circumferential direction. Also, as a modification, the thickness of the central portion in the tire circumferential direction and the thickness in the tire circumferential direction may change smoothly.

[0046] Similar to the first embodiment, the second embodiment also provides a non-pneumatic tire that allows for intuitive detection of abnormalities using relatively inexpensive means.

[0047] In particular, the second embodiment allows control over the fracture position of the connection, enabling the fracture position to be set in a way that facilitates confirmation of the fracture. Furthermore, the type and volume of the sound produced after the fracture can be adjusted.

[0048] (Third embodiment) In the first embodiment, the connecting portion 71 connects the flat surfaces of the first spoke 41 and the second spoke. However, the ease with which the connecting portion breaks may be adjusted by having the first spoke and the second spoke have a special structure for connecting the connecting portion. As such an embodiment, the third embodiment will be described with reference to Figure 11. Figure 11 is a schematic diagram (before breakage) showing the first spoke, the second spoke, and the abnormality detection structure as viewed in the tire radial direction in the third embodiment. Note that the basic structure of the third embodiment is the same as that of the first embodiment, so only the differences will be described below.

[0049] The first spoke 41 has a first projection 41c that protrudes in the tire circumferential direction C. The second spoke 42 has a second projection 41d that protrudes in the tire circumferential direction C.

[0050] The connection portion 71B of the anomaly detection structure 70B is a thin film, similar to the first embodiment. The connection portion 71B connects the first protrusion 41c and the second protrusion 41d.

[0051] The radial lengths of the first protrusion 41c and the second protrusion 41d are the same as the radial length of the connecting portion 71B. The thickness of the connecting portion 71B (length in the tire width direction Y) may be thinner than the thickness of the first protrusion 41c and the second protrusion 41d (length in the tire width direction Y).

[0052] Similar to the first embodiment, the third embodiment also provides a non-pneumatic tire that allows for intuitive detection of abnormalities using relatively inexpensive means.

[0053] (Fourth embodiment) In the first embodiment, the connecting portion 71 has its thin film ends positioned opposite each other in the tire radial direction X in order to connect the first spoke 41 and the second spoke in the tire circumferential direction C. A fourth embodiment will be described using Figure 12 as an example of such an embodiment. Figure 12 is a schematic diagram (before breakage) showing the first spoke, the second spoke, and the abnormality detection structure as viewed in the tire width direction in the fourth embodiment. Note that the basic structure of the fourth embodiment is the same as that of the first embodiment, so only the differences will be described below.

[0054] The first spoke 41 has a first projection 41e that protrudes in the tire circumferential direction C. The second spoke 42 has a second projection 41f that protrudes in the tire circumferential direction C.

[0055] The connection portion 71C of the anomaly detection structure 70C is a thin film, similar to the first embodiment. The connection portion 71C has both ends located on opposite sides in the tire radial direction X, and connects the first protrusion 41e and the second protrusion 41f.

[0056] Similar to the first embodiment, the fourth embodiment also provides a non-pneumatic tire that allows for intuitive detection of abnormalities using relatively inexpensive means.

[0057] (Description of the embodiment) <1> Non-pneumatic tire 1 is, A support structure 10 having an outer annular portion 30, an inner annular portion 20, and a plurality of spokes 40 arranged in the tire circumferential direction C, connecting the outer annular portion 30 and the inner annular portion 20, A tread 50 fixed to the outer annular portion 30, A pair of spokes 40 adjacent to each other in the tire circumferential direction C are connected by a connecting portion 71 which has lower strength than the spokes 40, It is equipped with this feature. This provides a non-pneumatic tire 1 that allows for the intuitive detection of abnormalities by relatively inexpensive means.

[0058] <2> <1> In the non-pneumatic tire 1 described above, the thickness t1 of the connecting portion 71 in the tire width direction Y is thinner than the thickness C of the spoke 40 in the tire circumferential direction. As a result, the strength of the connecting portion 71 is reliably lower than the strength of the spoke 40.

[0059] <3> <1> or <2> In the non-pneumatic tire 1 described above, the connecting portion 71 has the strength to break before the spoke 40 breaks, when the displacement of the spoke 40 reaches a predetermined value near the limit of the linear region. This ensures that the connecting portion 71 breaks before the spoke 40 breaks.

[0060] <4> <1> ~ <3> In any of the non-pneumatic tires 1 described above, Multiple spokes 40 are arranged such that when viewed in the circumferential direction C of the tire, adjacent pairs of spokes 40 intersect in an X shape. The connecting portion 71 connects the intersection portions 41a and 42a where adjacent pairs of spokes 40 intersect. As a result, the connecting portion 71 is formed along the partition line of the pair of spokes 40 (the linear portion along the joint between the upper and lower molds of the split mold). In other words, the connecting portion 71 can be formed simply by modifying the mold.

[0061] Although several embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the invention. In particular, the multiple embodiments and modifications described herein can be arbitrarily combined as needed.

[0062] The connecting portion may be formed only on a portion of the spoke intersection in the radial direction of the tire, rather than over the entire length. The connecting section may have a structure other than spokes that intersect in an X shape. The connecting parts are not provided between all spokes, but may be provided between some of the spokes.

[0063] Multiple connecting parts may be provided between a pair of spokes. For example, the connecting part may be composed of multiple thin, columnar members. [Explanation of symbols]

[0064] 1: Non-pneumatic tires 10:Support structure 20: Inner annular section 30:Outer annular part 40: Spoke (connecting part) 70: Anomaly detection structure 71: Connection part

Claims

1. A support structure having an outer annular portion, an inner annular portion, and a plurality of connecting portions arranged in the circumferential direction of the tire, connecting the outer annular portion and the inner annular portion. The tread fixed to the outer annular portion, A pair of adjacent connecting parts in the tire circumferential direction are connected to the aforementioned multiple connecting parts, and a connecting part with lower strength than the aforementioned connecting part is used. A non-pneumatic tire equipped with these features.

2. The non-pneumatic tire according to claim 1, wherein the thickness of the connecting portion in the tire width direction is thinner than the thickness of the connecting portion in the tire circumferential direction.

3. The non-pneumatic tire according to claim 1 or 2, wherein the connecting portion has the strength to break when the displacement of the connecting portion reaches a predetermined value near the limit of the linear region, before the connecting portion breaks.

4. The aforementioned plurality of connecting parts are such that, when viewed in the circumferential direction of the tire, adjacent pairs of connecting parts intersect in an X shape. The non-pneumatic tire according to claim 1 or 2, wherein the connecting portion connects the intersection portions where a pair of adjacent connecting portions intersect.

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