Pneumatic tire

Patent metadata

Field	Value
Publication number	US-2016200142-A1
Application number	US-201414913600-A
Country	US
Kind code	A1
Filing date	Aug 27, 2014
Priority date	Sep 10, 2013
Publication date	Jul 14, 2016
Grant date	—

Abstract

[Object] A pneumatic tire 2 that allows achievement of reduction of rolling resistance without taking influence on a mass into consideration, is provided.
[Solution] A profile OL of the tire 2 includes a ground-contact surface 46 and a pair of side surfaces 48 . In the profile OL, a zone from a point PB to a point PW is formed by three arcs. The arcs are a first arc, a second arc that extends almost outward from the first arc in the radial direction, and a third arc that extends almost outward from the second arc further in the radial direction. A ratio of a radius R2 of curvature of the second arc to a radius R1 of curvature of the first arc is greater than or equal to 1.45 and not greater than 3.26. A ratio of a radius R3 of curvature of the third arc to the radius R1 of curvature of the first arc is greater than or equal to 0.45 and not greater than 0.56. Each sidewall 8 of the tire 2 has a first recess 50 a and a second recess 50 b that are recessed inward from the side surface 48.

First claim

1 . A method for determining a carcass profile of a tire that includes a carcass, a belt layered over the carcass, and beads, the method comprising the steps of:
forming a representative carcass profile for a tire having a representative tire width, among tires for one aspect ratio, by applying a natural equilibrium shape theory, the representative carcass profile being a carcass profile having a natural equilibrium shape; and calculating a carcass profile based on the natural equilibrium shape theory, by using positions of four specific points of a point A, a point B, a point C, and a point D of a tire which has the same aspect ratio as the tire having the representative tire width and which has another tire width, the point A, the point B, the point C, and the point D corresponding to four specific points on the carcass profile, having the natural equilibrium shape, of the tire having the representative tire width, wherein in the carcass profile calculating step, the following mathematical expression for calculating a tire internal pressure share ratio Tb of the belt at any of positions Z on the carcass in a range in which the carcass and the belt are layered, is used
Tb=τo−a ( ZA−Z )/( ZA−ZB ),
ZA corresponds to a coordinate position of the point A in a Z-axis direction, ZB corresponds to a coordinate position of the point B in the Z-axis direction, on a cross-section perpendicular to a circumferential direction of the tire, the point A is a point of intersection of the carcass and a tire equator plane in a coordinate system in which: an originating point is a point of intersection of the tire equator plane and a tire rotation axis; a Y-axis represents a tire rotation axis direction; and a Z-axis represents a tire radial direction, the point B is a separation start point, in the coordinate system, at which the carcass and the belt separate from each other, τo represents a tire internal pressure share ratio of the belt at the point A, a represents a reduced amount of the share ratio τo at the point B, and a range from which values of τo and a are each selected, is provided for each aspect ratio of the tire.

2 . The method for determining the carcass profile according to claim 1 , wherein the carcass profile calculating step includes setting a specific point numerical value range by applying the natural equilibrium shape theory, and the specific point numerical value range is a range from which coordinate positions of at least three points among the point A, the point B, the point C, and the point D that are the four specific points of the tire having said another tire width, are selected.

3 . The method for determining the carcass profile according to claim 1 , wherein a Y-coordinate value B(y) of the point B is set within a range for each tire width, and a Z-coordinate value D(z) of the point D is set within a range for each tire width.

4 . The method for determining the carcass profile according to claim 1 , wherein
a Z-coordinate value A(z) of the point A is defined according to an inner diameter of a mold defined in a standard, a tread rubber thickness of a tread at a center portion in a tire axial direction, and a thickness of the belt, and a Y-coordinate value C(y) of the point C is defined according to ½ of an entire width of the mold defined in the standard, a thickness of a sidewall, and a thickness of a carcass in the case of the carcass having a highly turned-up structure.

5 . A pneumatic tire comprising:
a tread; a pair of sidewalls that extend from both ends, respectively, of the tread almost inward in a tire radial direction; a pair of beads disposed inward of the sidewalls, respectively, in a tire axial direction; a carcass extended, along inner sides of the tread and the sidewalls, on and between one of the beads and the other of the beads; and a belt layered outward of the carcass in the tire radial direction, wherein a shape of the carcass in the case of the tire being mounted to a rim and inflated to an internal pressure, is determined based on the natural equilibrium shape theory, and the method for determining the carcass profile according to claim 1 is applied for determining the shape of the carcass.

6 . A pneumatic tire comprising;
a tread; a pair of sidewalls that extend from ends, respectively, of the tread almost inward in a radial direction; a pair of clinches disposed inward of the sidewalls, respectively, in the radial direction; a pair of beads disposed inward of the clinches, respectively, in an axial direction; and a carcass extended, along inner sides of the tread and the sidewalls, on and between one of the beads and the other of the beads, wherein a profile of the tire includes a ground-contact surface, and a pair of side surfaces that extend from the ground-contact surface almost inward in the radial direction, a maximum value of a distance, in the axial direction, between both the side surfaces represents a maximum width of the tire, when: a boundary between the ground-contact surface and each side surface is a point PB; a point, on the side surface, representing the maximum width is a point PW; an imaginary straight line that extends through each point PW in the axial direction is a first reference line; a length, in the radial direction, from the first reference line to an equator is a first reference length; a point, on the side surface, which is disposed outward of the point PW in the radial direction, and which is distant from the first reference line in the radial direction, by a length corresponding to ⅓ of the first reference length, is a point PU1; a point, on the side surface, which is disposed outward of the point PU1 in the radial direction, and which is distant from the point PU1 in the radial direction, by a length corresponding to ⅓ of the first reference length, is a point PU2; a point, on the side surface, disposed at a mid-position between the point PU2 and the point PU1 in the radial direction, is a point PU3; a point, on the side surface, disposed at a mid-position between the point PU2 and the point PB in the radial direction, is a point PU4; an end point of the side surface is a point PT; an imaginary straight line that extends through each point PT in the axial direction is a second reference line; a length, in the radial direction, from the second reference line to the equator represents a cross-sectional height of the tire; a length, in the radial direction, from the second reference line to the point PW is a second reference length; a point, on the side surface, which is disposed inward of the point PW in the radial direction, and which is distant from the first reference line in the radial direction, by a length corresponding to ⅓ of the second reference length, is a point PL1; a point, on the side surface, which is disposed inward of the point PL1 in the radial direction, and which is distant from the first reference line in the radial direction, by a length corresponding to 11/20 of the second reference length, is a point PL2; and a thickness of each sidewall at the point PW is a reference thickness, a zone from the point PB to the point PW on each side surface is formed by three main arcs, the main arcs are a first main arc, a second main arc that extends almost outward from the first main arc in the radial direction, and a third main arc that extends almost outward from the second main arc further in the radial direction, the first main arc extends through the point PW and the point PU1, the second main arc extends through the point PU1, the point PU3, and the point PU2, the third main arc extends through the point PU2, the point PU4, and the point PB, a ratio of a radius RM2 of curvature of the second main arc to a radius RM1 of curvature of the first main arc is gr

Assignees

• Sumitomo Rubber Ind

Inventors

• Tomita Shintaro
• Tanaka Susumu
• Asano Kazuo

Classifications

• B60C3/04 Primary

  characterised by the relative dimensions of the section, e.g. low profile (B60C3/06 takes precedence) · CPC title

• B60C15/0036 Primary

  with high ply turn-up, i.e. folded around the bead core and terminating radially above the point of maximum section width · CPC title

• B60C13/003

  characterised by sidewall curvature · CPC title

• B60C9/18

  Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers · CPC title

• B60C13/00

  Tyre sidewalls; Protecting, decorating, marking, or the like, thereof (B60C17/08 takes precedence; tyre shoulders B60C11/01; removable tyre sidewall trim rings B60B7/01) · CPC title