JP2021127018A - tire - Google Patents

Abstract

To provide a tire which is capable of suppressing rim slip and/or rim detachment at high level and suppresses rolling resistance.SOLUTION: A tire includes two pairs composed of first parts (22a, 24a) where a profile (P) protrudes from a reference line (L) outside in a tire radial direction in a tire meridian cross-sectional view and second parts (22b, 24b) which protrude inside in the tire radial direction from the reference line in adjacency to the outside in a tire width direction of the first parts. The first parts and the second parts protrude within a range of 12 mm or less from a bead toe (T) in the reference line. Distance from the reference line to the second parts between both ends of the second parts increases from an outer end (E1) to an inner end (E2) in the tire width direction of the second parts.SELECTED DRAWING: Figure 2

Description

The present invention relates to a tire in which rim slippage and rim detachment are suppressed and rolling resistance is suppressed.

The tire radial inner surface (bead inner surface) of the bead part that comes into direct contact with the rim contributes to the sealing performance of the gas filled inside the tire, the rim slippage and / or the rim detachment suppression performance, and also the steering stability performance. Also affects. Therefore, it is important that the inner surface of the bead has a specific shape so as to ensure these performances.

With respect to such an inner surface of the bead, for example, a tire capable of reliably wiping off the applied lubricant at the time of rim assembly to reduce slippage has been proposed (Patent Document 1). That is, in Patent Document 1, a ridge that is formed so as to protrude from the surface of the bead heel portion and extends in the tire circumferential direction, and a ridge on the tire equatorial surface side in the tire axial direction of the ridge so as to be concave from the surface of the bead heel. A tire with a groove formed along a ridge is disclosed.

Similarly, regarding the inner surface of the bead, for example, based on providing a plurality of protrusions on the outer surface of the bead portion, a tire that maintains airtightness and facilitates rim assembly work even for a large tire has been proposed. (Patent Document 2). That is, Patent Document 2 includes a base surface in which the inner diameter of the bead portion is reduced inward in the tire axial direction and the bead portion is seated on the bead seat portion of the rim having a rim diameter of 440 mm or more and 630 mm or less. Disclosed are a tire having an outer shape that separates 10 mm outward in the tire radial direction from the outer surface and the rim diameter, and a tire that has a plurality of protrusions having a height of 0.05 mm or more and 0.95 m or less in a region separated within 10 mm. There is.

Japanese Unexamined Patent Publication No. 2013-39844 Japanese Unexamined Patent Publication No. 3-169727

However, in the tire disclosed in Patent Document 1, the portion where the unevenness is processed is only a small region near the bead heel. Therefore, considering the entire contact area with the rim, the inner surface of the bead is suitable in a wider area to ensure effective rim slip and / or rim disengagement, which has been required at an increasingly higher level in recent years. It is desirable to have a shape.

Further, in the tire disclosed in Patent Document 2, since the convex portion is simply provided on the inner surface of the bead up to that point, the weight is increased, and the fuel consumption may be deteriorated due to the increase in rolling resistance. be.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a tire capable of suppressing rim slippage and / or rim detachment at a high level and suppressing rolling resistance.

In the tire according to the present invention, in the tire meridional cross-sectional view, of the profile connecting the bead toe constituting the bead portion and the beat heel, the straight portion extending from the bead toe toward the outside in the tire width direction is further outside in the tire width direction. When the straight line extended to the above is used as the reference line, the profile has the first portion protruding outward in the tire radial direction from the reference line and the reference line adjacent to the outside in the tire width direction of the first portion. The tire includes two pairs consisting of a second portion protruding inward in the radial direction of the tire, and the first portion and the second portion project from a range within 12 mm from the bead toe of the reference line, and the above Between both ends of the second portion, the distance from the reference line to the second portion is characterized in that the distance from the outer end to the inner end in the tire width direction of the second portion increases.

In the tire according to the present invention, the tire profile in a relatively wide range near the bead toe in the tire meridional cross-sectional view is improved. As a result, according to the tire according to the present invention, rim slippage and rim detachment can be suppressed, and rolling resistance can be suppressed.

FIG. 1 is a cross-sectional view of a tire meridian showing a tire according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the tire meridian showing an enlarged view of the circled portion X in FIG. FIG. 3 is a cross-sectional view of the tire meridian showing the behavior of the tire according to the embodiment of the present invention when the tire is assembled at the rim. FIG. 4 is a partial cross-sectional perspective view showing a modified example of the tire shown in FIG.

Hereinafter, embodiments of the tire according to the present invention (basic embodiments and additional embodiments 1 to 3 shown below) will be described in detail with reference to the drawings. It should be noted that these embodiments do not limit the present invention. In addition, the components of the embodiment include those that can be easily replaced by those skilled in the art, or those that are substantially the same. Further, the various embodiments included in the embodiment can be arbitrarily combined within the scope of those skilled in the art.

[Basic form]
The basic form of the tire according to the present invention will be described. In the following description, the tire radial direction means a direction orthogonal to the rotation axis of the tire, the inner side of the tire radial direction is the side toward the rotation axis in the tire radial direction, and the outer side of the tire radial direction is the rotation axis in the tire radial direction. The side away from. The tire circumferential direction refers to a circumferential direction centered on the rotation axis. Further, the tire width direction means a direction parallel to the rotation axis, the inside in the tire width direction is the side toward the tire equatorial plane (tire equatorial line) in the tire width direction, and the outside in the tire width direction is in the tire width direction. The side of the tire away from the equatorial plane. The tire equatorial plane is a plane that is orthogonal to the rotation axis of the tire and passes through the center of the tire width of the tire.

FIG. 1 is a cross-sectional view of a tire meridian showing a tire according to an embodiment of the present invention. The example shown in FIG. 1 shows a state of a single tire that is not assembled on a regular rim.

The bead portion 10 of the tire shown in FIG. 1 is the innermost portion of the tire in the tire radial direction that comes into contact with the rim. The bead portion 10 shown in the figure is a bead core 12 which is a ring-shaped reinforcing material for bundling piano wires and the like, and a bead filler which is a reinforcing rubber layer which is located outside the bead core 12 in the tire radial direction to increase the rigidity of the bead portion. 14 and a chafer 16 which is a reinforcing cord located on the innermost side of the bead portion 10 in the tire radial direction to prevent the cord layer from touching the rim and being damaged, and the other portions are harder than the bead filler 14. It is composed of low rubber.

In FIG. 1, of the profile P (solid line portion in FIG. 1) connecting the bead toe T constituting the bead portion 10 and the beat heel H, a straight line portion extending outward in the tire width direction from the bead toe T (in the figure). A straight line obtained by extending the line segment between the point T and the point T'outward in the tire width direction is defined as the reference line L. In FIG. 1, the reference line L is shown by a solid line and a dotted line.

Here, the bead toe T means the inner end of the bead portion 10 in the tire width direction, and the bead heel H is the rim of the bead portion 10 in a no-load state in which the tire is assembled on the regular rim and the regular internal pressure is applied. It means the outer end in the tire width direction in contact.

The regular rim means the "applicable rim" specified in JATMA, the "Design Rim" specified in TRA, or the "Measuring Rim" specified in ETRTO. The normal internal pressure means the "maximum air pressure" specified in JATMA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified in TRA, or "INFLATION PRESSURES" specified in ETRTO.

Under such a premise, in the tire of the present embodiment, as shown in FIG. 1, the profile P has the first portions 22a and 24a protruding outward in the tire radial direction from the reference line L, and the first portion. Includes two pairs consisting of the second portions 22b and 24b adjacent to the outside in the tire width direction and protruding inward in the tire radial direction from the reference line L.

FIG. 2 is a cross-sectional view of the tire meridian showing an enlarged view of the circled portion X in FIG. In the tire of the present embodiment, as shown in FIG. 2, the first portions 22a and 24a and the second portions 22b and 24b protrude from the reference line L within 12 mm from the bead toe T.

Further, in the tire of the present embodiment, as shown in FIG. 2, the distance from the reference line L to the second portion 22b (24b) between both ends E1 and E2 of the second portion 22b (24b) is the second. The portion 22b (24b) of No. 2 increases from the outer end to the inner end in the tire width direction. The above distance refers to the dimension of a line segment from the reference line L to the second portion 22b (24b) of the straight line perpendicular to the reference line L in FIG.

(Action, etc.)
As described above, conventionally, a technique (Patent Document 1) has been known in which uneven processing is performed in the vicinity of the bead heel in order to reduce rim slippage. However, with this technology, the area where unevenness is applied to prevent rim slippage is a small area near the bead heel, so the effect is insufficient at present when rim slippage is required to be suppressed at an even higher level. there is a possibility.

Therefore, in the tire of the present embodiment, the profile P shown in FIG. 2 has two pairs (22a, 22b) (22a, 22b) consisting of the first and second portions protruding outward (inside) in the tire radial direction from the reference line L. 24a, 24b) are included. Therefore, the portion where the unevenness is processed to prevent rim slippage is set in a relatively wide area of the profile P connecting the bead toe T and the bead heel H, and as a result, rim slippage can be sufficiently suppressed.

When evaluating the rim slip, since the normal internal pressure is applied, it is considered that there is no great difference in the degree of contact (contact pressure) with the rim between the vicinity of the bead toe T and the vicinity of the bead heel H. Therefore, regardless of whether the uneven processing is applied in the vicinity of the bead heel H or in the vicinity of the bead toe T, the degree of suppression of rim slippage is determined by the convex portion formed by the uneven processing (in the present embodiment, the first It depends on the contact area between the parts 22b and 24b) of 2 and the rim. From such a viewpoint, since the convex portions are formed at two places (22b and 24b) in the present embodiment, the rim slip can be sufficiently suppressed (action effect 1). It is preferable that the second portions 22b and 24b forming the convex portion are formed on the entire circumference of the tire in that the above-mentioned action effect 1 is exhibited at a high level.

Further, in the tire of the present embodiment, the positions where the unevenness is processed (the positions where the first portions 22a and 24a and the second portions 22b and 24b are formed) are not near the bead heel H but near the bead toe T (of the reference line L). The reason why it is within 12 mm from the bead toe T) is as follows. That is, in general, in the state before the normal internal pressure is applied when the tire is assembled on the rim, the degree of contact with the rim (contact pressure) is lower in the vicinity of the bead toe T than in the vicinity of the bead heel H. Therefore, it is easier to fit the rim and the tire when the unevenness processing (particularly the convex portion) is applied in the vicinity of the bead toe T than in the case where the unevenness processing is applied in the vicinity of the bead heel H. From this point of view, in the present embodiment, the region to be subjected to the uneven processing is set to the vicinity of the bead toe T (action effect 2).

Next, FIG. 3 is a cross-sectional view of the tire meridian showing the behavior of the tire according to the embodiment of the present invention at the time of rim assembly. That is, when assembling the rim, the rim including the tire having the profile P shown in FIGS. The positional relationship with R changes.

In the tire of the present embodiment, as shown in FIG. 2, the distance from the reference line L to the second portion 22b (24b) between both ends (E1 and E2) of the second portion is the second portion 22b. (24b) increases from the outer end E1 in the tire width direction toward the inner end E2. As a result, in the behaviors leading to the upper, middle and lower figures of FIG. 3 (when the rim is assembled), the second portion 22b (24b) easily overcomes the hump RH of the rim R, while the lower figure, the middle figure and the lower figure of FIG. In the behavior leading to the above figure (when the rim comes off), it is difficult for the second portion 22b (24b) to get over the hump RH of the rim R. Therefore, a structure can be realized in which the tire can be easily fitted to the rim and the tire does not easily come off from the rim due to the suitable distance from the outer end E1 to the inner end E2, and the rim assembly is particularly easy. It is possible to sufficiently suppress the rim from coming off (action effect 3).

Further, in the present embodiment, in particular, not only the second portion 22b (24b) but also the first portion adjacent to the inside in the tire width direction of these portions and projecting to the opposite side in the tire radial direction from these portions. Part 22a (24a) is present. Therefore, in the behaviors (when the rim is assembled) leading to the upper, middle, and lower views of FIG. 3, the second portion 22b (24b) is easily deformed as compared with the case where the first portion 22a (24a) does not exist. Therefore, the second portion 22b (24b) can efficiently overcome the hump RH.

The evaluation of the rim detachment in the present embodiment is performed based on the test specified by JIS D4230. This test is a test for confirming the bead unseat phenomenon in which the tire comes off the rim, and the degree of passing in this embodiment is 6.67 kN when the nominal cross-sectional width is less than 160, 160 or more and 205. If it is less than, it is 8.89 kN, and if it is 205 or more, it is 11.12 kN. In addition, the degree to which this JIS standard is passed is No. 1 of the US Federal Motor Vehicle Safety Standards (FMVSS). It has passed the static bead unseat test specified in 109 and the SNI-00008 (so-called BUS test) in Indonesia, and this kind of test is currently being conducted in any country in the world. It is enough to pass the test.

By the way, conventionally, a technique of providing a convex portion on the inner surface of a bead in order to improve airtightness and rim assembly property (Patent Document 2) has been known. However, in this technique, the weight is increased due to the convex portion, and the fuel consumption may be deteriorated due to the increase in rolling resistance.

Therefore, in the tire of the present embodiment, the profile P shown in FIG. 2 has not only a convex portion (second portion (22b, 24b)) but also a concave portion (first portion (22a, 24a)). .. As a result, the weight increase due to the convex portion and the weight reduction due to the concave portion are substantially offset, and rolling resistance and thus fuel consumption can be suppressed (action effect 4).

Therefore, according to the tire of the present embodiment, the above-mentioned effects 1 to 4 are combined, and in particular, rim slippage and rim detachment can be suppressed, and rolling resistance can be suppressed.

The tire of the present embodiment shown above has a meridional cross-sectional shape similar to that of a conventional tire, although the entire tire is not shown. That is, the tire of the present embodiment has a bead portion, a sidewall portion, a shoulder portion, and a tread portion from the inside to the outside in the tire radial direction in a cross-sectional view of the tire meridian. Then, the tire has, for example, a carcass layer extending from the tread portion to the bead portions on both sides and wound around a pair of bead cores in a cross-sectional view of the tire meridian, and the outer side of the carcass layer in the tire radial direction. In addition, a belt layer as described above and, in some cases, a belt cover layer are provided.

Further, the tire of the present embodiment shown above undergoes each of the usual manufacturing processes, that is, a tire material mixing process, a tire material processing process, a green tire molding process, a vulcanization process, an inspection process after vulcanization, and the like. It is obtained through the process. When the tire of the present embodiment is manufactured, convex portions and concave portions corresponding to a predetermined tread pattern are formed on the inner wall of the vulcanization mold, and vulcanization is performed using this mold.

The tire of the present embodiment shown above has been described by taking a pneumatic tire as an example, but a tire other than the pneumatic tire that satisfies the requirements of the present embodiment with respect to a portion that comes into contact with the rim. If there is, it is included in the scope of the present invention.

[Additional form]
Next, additional embodiments 1 to 3 which can be optionally implemented with respect to the basic embodiment of the tire according to the present invention will be described.

(Additional form 1)
In the basic form, the maximum distance of the second portion 22b (24b) shown in FIG. 2 from the reference line L is 0.5 mm or more and 2.0 mm or less, and the reference line L of the second portion 22b (24b) is formed. It is preferable that the dimension along the tire is 0.5 mm or more and 2.0 mm or less, and the second portion 22b (24b) has the same shape over the entire circumference of the tire (additional form 1).

The maximum distance of the second portion 22b (24b) from the reference line L shall be 0.5 mm or more, and the dimension of the second portion 22b (24b) along the reference line L shall be 0.5 mm or more. Therefore, the contact area with the rim can be further increased at the two convex portions (22b and 24b), and the rim slippage can be further suppressed.

On the other hand, the maximum distance of the second portion 22b (24b) from the reference line L is set to 2.0 mm or less, and the dimension of the second portion 22b (24b) along the reference line L is 2.0 mm. By doing so, the tire can be more easily fitted to the rim without making the contact area with the rim excessive at the two convex portions (22b, 24b).

When the maximum distance is 0.6 mm or more and 1.9 mm or less, the above effects are exhibited at a higher level, and when the maximum distance is 0.7 mm or more and 1.8 mm or less, the above effects are extremely effective. Played at a high level. Similarly, when the dimensions are 0.6 mm or more and 1.9 mm or less, the above effects are exhibited at a higher level, and when 0.7 mm or more and 1.8 mm or less, the above effects are extremely effective. Played at a high level.

In addition, by making the second portion 22b (24b) the same shape over the entire circumference of the tire, it is possible to prevent a local shortage of rubber flow in the tire circumferential direction when the green tire is vulcanized. As a result, so-called vulcanization failure can be avoided, the tire uniformity can be improved, and the formation of a portion that becomes a starting point of fracture during traveling can be suppressed.

(Additional form 2)
In the basic form or the form in which the additional form 1 is added to the basic form, the area of the recess C1 surrounded by the reference line L shown in FIG. 2 and the first portion 22a (24a) is the reference line L and the second portion. It is preferable that the area of the convex portion C2 surrounded by the portion 22b (24b) is 0.5 times or more and 1.2 times or less (additional form 2).

The area of the concave portion C1 surrounded by the reference line L and the first portion 22a (24a) is 0.5 times or more the area of the convex portion C2 surrounded by the reference line L and the second portion 22b (24b). By doing so, it is possible to further prevent the area of the convex portion C2 from becoming excessively large. As a result, the tire can be fitted to the rim even more easily without making the contact area with the rim excessive.

On the other hand, the area of the concave portion C1 surrounded by the reference line L and the first portion 22a (24a) is the area of the convex portion C2 surrounded by the reference line L and the second portion 22b (24b). By setting the value to 2 times or less, it is possible to further prevent the area of the recess C1 from becoming excessively large. As a result, the rigidity in the vicinity of the bead toe T can be further increased, and as a result, the steering stability performance can be improved.

When the area of the concave portion C1 is 0.6 times or more and 1.1 times or less of the area of the convex portion C2, the above effects are exhibited at a higher level, and 0.7 times or more and 1.0 times or less. If so, the above effects are achieved at extremely high levels.

(Additional form 3)
FIG. 4 is a partial cross-sectional perspective view showing a modified example of the tire shown in FIG. In the basic form or the form in which at least one of the additional forms 1 and 2 is added to the basic form, as shown in FIG. 4, one convex portion (a portion surrounded by the reference line L and the second portion 22b). The line segment connecting the innermost ends E3 and E4 in the tire radial direction between the two convex portions (the portion surrounded by the reference line L and the second portion 24b) and the other convex portion is the ridge line LR (same as above). It is preferable to include a small convex portion S having a tire circumferential dimension of 0.5 mm or more and 1.0 mm or less (additional form 3).

By further providing the small convex portion S having the above configuration, the rubber flow can be further promoted when the green tire is vulcanized. As a result, so-called vulcanization failure can be avoided at a higher level, and it is possible to suppress the formation of a portion that becomes a starting point of fracture during traveling.

The tire circumferential dimension of the small convex portion S was set to 0.5 mm or more in order to sufficiently effectively prevent the above-mentioned vulcanization failure, while the rim was set to 1.0 mm or less. This is to make it easier to fit the tire with the tire. From such a viewpoint, it is more preferable that the tire circumferential dimension of the small convex portion S is 0.6 mm or more and 0.9 mm or less, respectively.

The tire size was 215 / 45R18 89W (specified by JATTA), and the tires of Invention Examples 1 to 4 and the tires of the conventional example having the bead portion having the shape shown in FIG. 1 (FIG. 2) or FIG. 4 were produced. The detailed conditions of these tires are shown in Table 1 below.

In Table 1, the first part, the second part, the bead heel, the bead toe, the reference line, the concave portion, the convex portion and the small convex portion are based on the definitions and the like described in this specification. Further, the vicinity of the bead toe means a range within 12 mm from the bead toe in the reference line, and it is shown in FIG. 2 that the shape change of the second portion from the outside to the inside in the tire width direction is gradually wide. As described above, the distance from the reference line L to the second portion between both ends of the second portion 22b (24b) increases from the outer end E1 to the inner end E2 in the tire width direction of the second portion. Means that.

The tires of Invention Examples 1 to 4 and the tires of the conventional examples produced in this manner were evaluated for fitting performance to the rim, bead unseat performance, and rolling resistance according to the following procedure.

(Matching performance to rim)
When assembling each test tire to a rim having a rim size of 18 × 7.0J, the pressure (fitting pressure) when the bead portion coated with the bead cream overcame the hump of the rim was measured. The fitting pressure was measured 10 times for each test tire, and the average value was calculated. The evaluation result was an index of 100 in the conventional example. The results are also shown in Table 1. The larger the index value, the lower the fitting pressure and the better the rim assembly property.

(Bead unseat performance)
Each test tire was assembled on a rim having a rim size of 18 × 7.0J, filled with a test air pressure of 230 kPa, and the bead unseat resistance value (N) was measured in accordance with JIS D4230. The evaluation result was an index of 100 in the conventional example. The results are also shown in Table 1. The larger the index value, the better the bead unseat performance (rim removal resistance).

(Rolling resistance performance)
Each test tire was assembled on a rim with a rim size of 18 × 7.0J and mounted on a drum tester, and the rolling resistance coefficient (RRC) was measured in accordance with ISO25280 under the conditions of an air pressure of 230 kPa and a load of 4.82N. .. The evaluation result was an index with the reciprocal of the measured value as 100 in the conventional example. The results are also shown in Table 1. The larger the index value, the better the rolling resistance performance.

According to Table 1, any of the tires of Invention Examples 1 to 4 belonging to the technical scope of the present invention (improved tire profile in a relatively wide range near the bead toe in the tire meridional cross-sectional view). However, it can be seen that the fitting performance to the rim, the bead unseat performance and the rolling resistance performance are improved in a well-balanced manner as compared with the conventional tires which do not belong to the technical scope of the present invention.

10 Bead part 12 Bead core 14 Bead filler 16 Chafer 22a, 24a First part 22b, 24b Second part 22c, 24c
C1 Concave part C2 Convex part E1 Outer end in tire width direction of second part E2 Inner end in tire width direction of second part E3, E4
H Bead heel L Reference line LR Ridge line P Profile R Rim RH Hump S Small convex part T Bead toe T'The outermost point in the tire width direction of the straight part extending outward from the bead toe T in the tire width direction X Circled part

Claims (4)

In the tire meridional cross-sectional view, of the profile connecting the bead toe and the beat heel constituting the bead portion, the straight line portion extending outward in the tire width direction from the bead toe is further extended outward in the tire width direction as a reference line. When
A first portion in which the profile protrudes outward in the tire radial direction from the reference line, and a second portion in which the first portion protrudes inward in the tire radial direction from the reference line adjacent to the outside in the tire width direction. Including two pairs consisting of
The first portion and the second portion protrude from a range of the reference line within 12 mm from the bead toe.
The distance from the reference line to the second portion between both ends of the second portion is characterized by increasing from the outer end to the inner end in the tire width direction of the second portion. tire. The maximum distance of the second portion from the reference line is 0.5 mm or more and 2.0 mm or less, and the dimension of the second portion along the reference line is 0.5 mm or more and 2.0 mm or less. The tire according to claim 1, wherein the second portion has the same shape over the entire circumference of the tire. Claim that the area of the concave portion surrounded by the reference line and the first portion is 0.5 times or more and 1.2 times or less the area of the convex portion surrounded by the reference line and the second portion. Item 2. The tire according to item 1 or 2. A line segment connecting the innermost ends of the two convex portions in the tire radial direction between one convex portion and the other convex portion is defined as a ridge line, and the tire circumferential dimension is 0.5 mm or more. The tire according to any one of claims 1 to 3, which includes a small convex portion having a size of 0 mm or less.

Images