Patent Grant
10836211
The present invention relates to a non-pneumatic tire which does not need to be filled with pressurized air, when in use.
This application is a National Stage of International Application No. PCT/JP2016/079405, filed on Oct. 4, 2016, which claims priority from Priority is claimed on Japanese Patent Application No. 2015-201279, filed Oct. 9, 2015, the content of which is incorporated herein by reference.
In conventional pneumatic tires which are filled with pressurized air and used, occurrence of a flat tire is an inevitable problem from a structural perspective.
To resolve such a problem, in recent years, a non-pneumatic tire including an attachment body attached to an axle, an outer cylindrical body which surrounds the attachment body from the outside in the tire radial direction, and a coupling body which couples the outer cylindrical body and the attachment body has been proposed as described in Patent Document 1 below, for example. The coupling body includes a plurality of coupling members disposed at intervals in a tire circumferential direction, opposite ends of each of the coupling members are respectively coupled to the attachment body and the outer cylindrical body, and a first end portion which is an outer end portion in the tire radial direction is positioned on one side in the tire circumferential direction of a second end portion which is an inner end portion in the tire radial direction.
[Patent Document 1]
Japanese Unexamined Patent Application, First Publication No. 2013-86712
However, in such a conventional non-pneumatic tire, there is room for improvement in preventing concentration of stress generated in the coupling member when a load is applied to the non-pneumatic tire and in enhancing durability.
The present invention is made in consideration of the above-described circumstances, and an object of the present invention is to enhance durability.
A non-pneumatic tire according to the present invention includes an attachment body attached to an axle, an outer cylindrical body which surrounds the attachment body from the outside in a tire radial direction, and a coupling body which couples the outer cylindrical body and the attachment body, in which the coupling body includes a plurality of coupling members disposed at intervals in a tire circumferential direction, opposite ends of each of the coupling members are respectively coupled to the attachment body and the outer cylindrical body, and a first end portion which is an outer end portion of the coupling member in the tire radial direction is positioned on one side in the tire circumferential direction of a second end portion which is an inner end portion in the tire radial direction, in which, in a tire side view when the non-pneumatic tire is viewed from a tire width direction, when a first point, a second point, a third point, a fourth point, and a fifth point are set in order from the first end portion side toward the second end portion side on a center line passing through a center in the tire circumferential direction of the coupling member over the entire length from the first end portion to the second end portion of the coupling member, when the first point is set on an end edge on the first end portion side of the coupling member and the fifth point is set on an end edge on the second end portion side of the coupling member, and when a distance H1 from the fifth point to the second point along a reference straight line passing through the first point and a tire axis is set to 0.80 times a reference distance H from the fifth point to the first point along the reference straight line, a distance H2 from the fifth point to the third point along the reference straight line is set to 0.65 times the reference distance H, and a distance H3 from the fifth point to the fourth point along the reference straight line is set to 0.30 times the reference distance H, the third point is disposed on the other side in the tire circumferential direction of an overall inclined straight line passing through the first point and the fifth point, and a horizontal distance D2 between the second point and the third point in a perpendicular direction perpendicular to the reference straight line is larger than each of a horizontal distance D1 between the first point and the second point in the perpendicular direction and a horizontal distance D4 between the fourth point and the fifth point in the perpendicular direction.
According to the present invention, durability can be enhanced.
As shown in
Also, the non-pneumatic tire 1 of the present embodiment may be employed in a small-sized vehicle traveling at a low speed such as a handle type electric wheelchair specified in Japanese Industrial Standard JIS T 9208, for example. In addition, the size of the non-pneumatic tire 1 is not particularly limited, but may be in a range of 3.00-8 or the like, for example. Also, the non-pneumatic tire 1 may be employed for passenger cars. The size in this case is not particularly limited, but may be 155/65R 13 or the like, for example.
The above-described attachment body 11, the outer cylindrical body 13, and the tread member 16 are coaxially arranged on a common axis. Hereinafter, this common axis is referred to as an axis O, a direction along the axis O is referred to as a tire width direction, a direction perpendicular to the axis O is referred to as a tire radial direction, and a direction of revolving around the axis O is referred to as a tire circumferential direction. Also, center portions in the tire width direction of the attachment body 11, the outer cylindrical body 13, and the tread member 16 coincide with each other.
The attachment body 11 includes a fitting cylinder portion 17 to which a distal end portion of the axle is fitted, an outer ring portion 18 which surrounds the fitting cylinder portion 17 from the outside in the tire radial direction, and a plurality of ribs 19 which couple the fitting cylinder portion 17 to the outer ring portion 18.
The fitting cylinder portion 17, the outer ring portion 18, and the ribs 19 are integrally formed of a metal material such as an aluminum alloy, for example. The fitting cylinder portion 17 and the outer ring portion 18 are formed in a cylindrical shape and are coaxially arranged on the axis O. The plurality of ribs 19 are disposed at regular intervals in the tire circumferential direction, for example.
A plurality of key groove portions (not shown) recessed toward the inside in the tire radial direction and configured to extend in the tire width direction are formed on an outer circumferential surface of the outer ring portion 18 at intervals in the tire circumferential direction. On the outer circumferential surface of the outer ring portion 18, the key groove portions are open only on one side (outer side of the vehicle body) in the tire width direction and are closed on the other side (inside the vehicle body) in the tire width direction.
An inner cylindrical body 12 in a cylindrical shape which is externally fitted to the outer ring portion 18 is provided on the attachment body 11. A ridge portion (not shown) protruding toward the inside in the tire radial direction and extending over the entire length in the tire width direction is formed on an inner circumferential surface of the inner cylindrical body 12. A plurality of ridge portions are formed on the inner circumferential surface of the inner cylindrical body 12 at intervals in the tire circumferential direction and respectively engaged with the key groove portions.
Thus, the inner cylindrical body 12 is fixed to the attachment body 11 in a state in which the ridge portions are engaged with the key groove portions. In the shown example, the inner cylindrical body 12 is fixed to the attachment body 11 by screwing plates 28 from one side in the tire width direction at a position corresponding to the key groove portions in the outer ring portion 18.
A plurality of coupling bodies 14 are arranged in a tire circumferential direction between the attachment body 11 and the outer cylindrical body 13, and each of the coupling bodies 14 includes a coupling member 15 which couples the attachment body 11 and the outer cylindrical body 13 in an elastically relatively displaceable manner. A plurality of coupling members 15 are disposed at intervals in the tire circumferential direction, opposite ends of each of the coupling members 15 are respectively coupled to the attachment body 11 and the outer cylindrical body 13, and a first end portion (outer end portion 15a) which is an outer end portion in the tire radial direction is positioned on one side in the tire circumferential direction of the second end portion (inner end portion 15b) which is an inner end portion in the tire radial direction. The coupling member 15 gradually extends toward the other side in the tire circumferential direction from the outside toward the inside in the tire radial direction.
The coupling member 15 couples an outer circumferential surface side of the attachment body 11 to an inner circumferential surface side of the outer cylindrical body 13 in an elastically relatively displaceable manner. The coupling member 15 is an elastically deformable plate whose front and rear surfaces are directed in the tire circumferential direction. A plurality of coupling members 15 are disposed in the tire circumferential direction. The plurality of coupling members 15 are respectively disposed at positions rotationally symmetrical with respect to the axis O between the inner cylindrical body 12 and the outer cylindrical body 13. All the coupling members 15 have the same shape and the same size, and the width of the coupling members 15 in the tire width direction is smaller than the width of the outer cylindrical body 13 in the tire width direction. Adjacent coupling members 15 in the tire circumferential direction are not in contact with each other.
As shown in
A plurality of curved portions 15d to 15f which are curved in the tire circumferential direction are formed in the coupling member 15 at intermediate portions between the outer end portion 15a and the inner end portion 15b. The plurality of curved portions 15d to 15f are formed along an extending direction in which the coupling member 15 extends in a tire side view when the non-pneumatic tire 1 is viewed from the tire width direction. In the shown example, the plurality of curved portions 15d to 15f of the coupling member 15 are adjacent to each other in the above-described extending direction while having curvature directions opposite to each other.
The plurality of curved portions 15d to 15f include a first curved portion 15d curved to protrude toward the other side in the tire circumferential direction, a second curved portion 15e positioned between the first curved portion 15d and the outer end portion 15a and curved to protrude toward one side in the tire circumferential direction, and a third curved portion 15f positioned between the first curved portion 15d and the inner end portion 15b and curved to protrude toward one side in the tire circumferential direction. In addition, inflection portions 15g and 15h are formed in the coupling member 15 at portions positioned between each of the curved portions 15d to 15f adjacent to each other in the extending direction of the coupling member 15.
The above-described inner cylindrical body 12, the outer cylindrical body 13, and the plurality of coupling members 15 (the coupling body 14) are integrally formed of a synthetic resin material, for example. The synthetic resin material may be, for example, a single resin material, a mixture containing two or more kinds of resin material, or a mixture containing one or more kinds of resin material and one or more kinds of elastomer, and furthermore, may include additives such as anti-aging agents, plasticizers, fillers, or pigments, for example.
Hereinafter, a unit in which the inner cylindrical body 12, the outer cylindrical body 13, and the coupling member 15 are integrally formed is referred to as a case body 31.
The case body 31 can be integrally formed by injection molding, for example. The injection molding may include a general method of molding the entire case body 31 at once, insert molding in which the remaining portions other than insert parts are injection molded with some portions among the inner cylindrical body 12, the outer cylindrical body 13, and the coupling member 15 being provided as the insert parts, a so-called two-color molding, or the like. In addition, when the entirety of the case body 31 is injection-molded at once, a plurality of protrusions formed on the inner cylindrical body 12 may be a gate portion. Further, at the time of injection-molding, the inner cylindrical body 12, the outer cylindrical body 13, and the coupling member 15 may be formed of different materials, or may be formed of the same material. As such materials, metal materials, resin materials, or the like are examples; however, resin materials, particularly thermoplastic resins, are preferable from the perspective of reducing weight.
As shown in
As the thermoplastic material, a thermoplastic elastomer, a thermoplastic resin, or the like is an example. As thermoplastic elastomers, amide-based thermoplastic elastomers (TPA), ester-based thermoplastic elastomers (TPC), olefin-based thermoplastic elastomers (TPO), styrene-based thermoplastic elastomers (TPS), urethane-based thermoplastic elastomers (TPU), a thermoplastic rubber cross-linked body (TPV), other thermoplastic elastomers (TPZ), or the like, specified in Japanese Industrial Standard JIS K6418, are examples.
As the thermoplastic resin, urethane resins, olefin resins, vinyl chloride resins, polyamide resins, or the like are examples. Also, it is preferable to form the tread member 16 with a vulcanized rubber from the perspective of wear resistance.
In the present embodiment, the non-pneumatic tire 1 satisfies the following relationships.
That is, first, as shown in
At this time, as shown in
In the present embodiment, a horizontal distance D3 between the third point P3 and the fourth point P4 in the perpendicular direction D is larger than each of the horizontal distance D1 and the horizontal distance D4.
As shown in
That is, when a portion in which the third point P3 is positioned protrudes to the other side in the tire circumferential direction, a portion in which the second point P2 is positioned protrudes to one side in the tire circumferential direction.
Also, as shown in
Further, an inclination angle θ3 of a third inclined straight line SL3 passing through the third point P3 and the fourth point P4 with respect to the perpendicular direction D is larger than the inclination angle θ2, and the inclination angle θ4 is larger than the inclination angle θ3.
Thus, a thickness (plate thickness) which is a size in the tire circumferential direction of the coupling member 15 gradually decreases (becomes thinner) from each of the first point P1 and the fifth point P5 toward the fourth point P4.
Also, in the present embodiment, an inclination angle θ of the overall inclined straight line SL with respect to the perpendicular direction D and the inclination angle θ3 satisfy a relationship of the following expression (1).
0.9<(θ3/θ)<1.2 (1)
Further, in the present embodiment, the inclination angles θ1, θ2, θ3, and θ4 satisfy relationships of the following expressions (2) to (5).
0.35<(θ2/θ1)<0.95 (2)
0.3<(θ2/θ4)<0.8 (3)
0.4<(θ2/θ3)<0.9 (4)
0.7<(θ3/θ4)<0.95 (5)
Further, it is preferable that the inclination angles θ, θ1, θ2, θ3, and θ4 satisfy relationships of the following expressions (1)′ to (5)′.
1.00≤(θ3/θ)≤1.10 (1)′
0.44≤(θ2/θ1)≤0.89 (2)′
0.38≤(θ2/θ4)≤0.67 (3)′
0.46≤(θ2/θ3)≤0.80 (4)′
0.82≤(θ3/θ4)≤0.92 (5)′
As described above, according to the non-pneumatic tire 1 of the present embodiment, since the third point P3 is disposed on the other side in the tire circumferential direction of the overall inclined straight line SL, it is possible to cause the portion of the coupling member 15 at which the third point P3 is positioned to protrude to the other side in the tire circumferential direction. In addition, since the horizontal distance D2 between the second point P2 and the third point P3 is larger than the horizontal distance D1 between the first point P1 and the second point P2 and the horizontal distance D4 between the fourth point P4 and the fifth point P5, a portion of the coupling member 15 positioned between the second point P2 and the third point P3 can to a great extent be easily made to lie against the reference straight line RL.
As described above, when a compressive force in the tire radial direction is applied to the coupling member 15 between the attachment body 11 and the outer cylindrical body 13, a center portion of the coupling member 15 from the second point P2 to the fourth point P4 through the third point P3 is gently bent and deformed toward the other side in the tire circumferential direction so that the both end portions of the coupling member 15 cannot be easily deformed. Thereby, concentration of stress in the coupling member 15 can be prevented and durability can be enhanced.
In addition, the inclination angle θ2 of the second inclined straight line SL2 is smaller than the inclination angle θ1 of the first inclined straight line SL1 and the inclination angle θ4 of the fourth inclined straight line SL4. Therefore, the portion of the coupling member 15 positioned between the second point P2 and the third point P3 can be reliably made to lie against the reference straight line RL.
Since the inclination angle θ3 of the third inclined straight line SL3 is larger than the inclination angle θ2 of the second inclined straight line SL2, the center portion of the coupling member 15 is formed to protrude toward the other side in the tire circumferential direction in a tire side view so that it can be easily bent and deformed.
Since the inclination angle θ4 of the fourth inclined straight line SL4 is larger than the inclination angle θ3 of the third inclined straight line SL3, a portion of the coupling member 15 positioned between the fourth point P4 and the fifth point P5 can be raised up as compared with the portion positioned between the second point P2 and the third point P3. Thereby, it is possible to effectively prevent deformation of the inner end portion 15b of the coupling member 15.
In addition, since a size of the coupling member 15 in the tire circumferential direction gradually decreases from each of the first point P1 and the fifth point P5 toward the fourth point P4, when the coupling member 15 is deformed, it is possible to easily deform the coupling member 15 with a portion positioned on the fourth point P4 of the coupling member 15 as a starting point. Thereby, it is possible to actively and easily bend and deform the center portion of the coupling member 15.
The technical scope of the present invention is not limited to the above embodiments, and various modifications can be added to the scope of the present invention without departing from the spirit of the present invention.
For example, although in the above-described embodiment, the inner cylindrical body 12, the outer cylindrical body 13, and the coupling member 15 are integrally formed by, for example, injection molding, the present invention is not limited to injection molding, and they may be integrally formed by, for example, casting or the like. Also, the inner cylindrical body 12, the outer cylindrical body 13, and the coupling member 15 may be individually formed and then coupled to each other.
Further, in the embodiment described above, the coupling member 15 is indirectly coupled to the outer ring portion 18 of the attachment body 11 via the inner cylindrical body 12, but the present invention is not limited thereto, and, for example, the coupling member 15 may be directly coupled to the outer ring portion 18 of the attachment body 11. In this case, the end edge on the inner end portion 15b side of the coupling member 15 is positioned on the outer circumferential surface of the outer ring portion 18, and the fifth point P5 can be set on the outer circumferential surface of the outer ring portion 18.
In addition, the components in the above-described embodiments can be appropriately replaced with well-known components without departing from the spirit and scope of the present invention, and furthermore, the above-described modified examples may be appropriately combined.
Next, a verification test on the operation and effects described above was conducted.
In this verification test, for each non-pneumatic tire of a comparative example and an example, in a simulation using a finite element method, maximum values of stress generated in tires when a load was applied were compared.
With the non-pneumatic tire shown in
In Table 1, the unit of each value of the inclination angles θ1 to θ4, and θ is “degrees (°)” and the unit of each value of the horizontal distances D1 to D4 is “millimeters (mm).”
As shown in each value in Table 1, in the non-pneumatic tire of the example, a horizontal distance D2 was larger than each of horizontal distances D1 and D4, an inclination angle θ2 was smaller than each of inclination angles θ1 and θ4, an inclination angle θ3 was larger than the inclination angle θ2, and the inclination angle θ4 was larger than the inclination angle θ3.
On the other hand, in the non-pneumatic tire of the comparative example, a horizontal distance D2 was smaller than each of horizontal distances D1 and D4, an inclination angle θ2 was larger than each of inclination angles θ1 and θ4, an inclination angle θ3 was smaller than the inclination angle θ2, and the inclination angle θ4 was smaller than an inclination angle θ3.
As a result of this verification test, it was confirmed that a maximum stress in the non-pneumatic tire of the example was reduced to 55 when a maximum stress in the non-pneumatic tire of the comparative example was set to 100.
According to the present invention, since the third point is disposed on the other side in the tire circumferential direction of the overall inclined straight line, it is possible to cause a portion of the coupling member in which the third point is positioned to protrude to the other side in the tire circumferential direction. In addition, since the horizontal distance D2 between the second point and the third point is larger than the horizontal distance D1 between the first point and the second point and larger than the horizontal distance D4 between the fourth point and the fifth point, a portion of the coupling member positioned between the second point and the third point can to a great extent be easily made to lie against the reference straight line.
As described above, when a compressive force in the tire radial direction is applied to the coupling member between the attachment body and the outer cylindrical body, a center portion of the coupling member from the second point to the fourth point through the third point is gently bent and deformed toward the other side in the tire circumferential direction so that the both end portions of the coupling member cannot be easily deformed. Thereby, concentration of stress in the coupling member can be prevented and durability can be enhanced.
The inclination angle θ2 of the second inclined straight line passing through the second point and the third point with respect to the perpendicular direction may be smaller than the inclination angle θ1 of the first inclined straight line passing through the first point and the second point with respect to the perpendicular direction and smaller than the inclination angle θ4 of the fourth inclined straight line passing through the fourth point and the fifth point with respect to the perpendicular direction.
In this case, the inclination angle θ2 of the second inclined straight line is smaller than each of the inclination angle θ1 of the first inclined straight line and the inclination angle θ4 of the fourth inclined straight line. Therefore, the portion of the coupling member positioned between the second point and the third point can to a great extent be reliably made to lie against the reference straight line.
The inclination angle θ3 of the third inclined straight line passing through the third point and the fourth point with respect to the perpendicular direction may be larger than the inclination angle θ2.
In this case, since the inclination angle θ3 of the third inclined straight line is larger than the inclination angle θ2 of the second inclined straight line, the center portion of the coupling member is formed to protrude toward the other side in the tire circumferential direction in a tire side view so that it can be easily bent and deformed.
The inclination angle θ4 may be larger than the inclination angle θ3.
In this case, since the inclination angle θ4 of the fourth inclined straight line is larger than the inclination angle θ3 of the third inclined straight line, the portion of the coupling member positioned between the fourth point and the fifth point can be raised up as compared with the portion positioned between the second point and the third point. Thereby, it is possible to effectively prevent deformation of the second end portion of the coupling member.
The size of the coupling member in the tire circumferential direction may gradually decrease from each of the first point and the fifth point toward the fourth point.
In this case, since the size of the coupling member in the tire circumferential direction gradually decreases from each of the first point and the fifth point toward the fourth point, when the coupling member is deformed, it is possible to easily deform the coupling member with a portion positioned on the fourth point of the coupling member as a starting point. Thereby, it is possible to actively and easily bend and deform the center portion of the coupling member.
According to the present invention, durability of the non-pneumatic tire can be enhanced.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-201279 | Oct 2015 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2016/079405 | 10/4/2016 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2017/061405 | 4/13/2017 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 1187042 | Baker | Jun 1916 | A |
| 1442897 | Murray | Jan 1923 | A |
| 20040069385 | Timoney | Apr 2004 | A1 |
| 20090294000 | Cron | Dec 2009 | A1 |
| 20130240097 | Cron | Sep 2013 | A1 |
| 20140062168 | Martin | Mar 2014 | A1 |
| 20140251518 | Abe et al. | Sep 2014 | A1 |
| 20150174953 | Cron | Jun 2015 | A1 |
| 20150246577 | Fudemoto | Sep 2015 | A1 |
| 20150273946 | Abe et al. | Oct 2015 | A1 |
| 20150283851 | Abe et al. | Oct 2015 | A1 |
| 20160167434 | Nishida et al. | Jun 2016 | A1 |
| 20160250893 | Shoji et al. | Sep 2016 | A1 |
| 20160272006 | Abe | Sep 2016 | A1 |
| Number | Date | Country |
|---|---|---|
| 103129308 | Jun 2013 | CN |
| 104736355 | Jun 2015 | CN |
| 2 679 406 | Jan 2014 | EP |
| 191601 | Jan 1923 | GB |
| 3-189202 | Aug 1991 | JP |
| 2013-086712 | May 2013 | JP |
| 2014-091453 | May 2014 | JP |
| 2014-189095 | Oct 2014 | JP |
| 2015-080965 | Apr 2015 | JP |
| 2014069570 | May 2014 | WO |
| 2015072314 | May 2015 | WO |
| Entry |
|---|
| Communication dated Aug. 28, 2018 from the European Patent Office in counterpart application No. 16853559.9. |
| International Search Report for PCT/JP2016/079405 dated Nov. 8, 2016 [PCT/ISA/210]. |
| Communication dated Jun. 27, 2019 from the China National Intellectual Property of Administration in counterpart Application No. 201680058303.6. |
| Number | Date | Country | |
|---|---|---|---|
| 20180222254 A1 | Aug 2018 | US |
