JP6562130B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire that can exhibit excellent noise performance while maintaining steering stability.

  For example, Patent Document 1 below proposes a pneumatic tire in which a narrow groove extending continuously in the tire circumferential direction is provided in a land portion divided by a main groove in order to achieve both wet performance and noise performance. Has been. In this pneumatic tire, the groove width and depth of the narrow groove are specified within a certain range.

  However, in Patent Document 1, there is room for further improvement with respect to reduction of air column resonance generated in the main groove and steering stability.

JP 05-319027 A

  The present invention has been devised in view of the above problems, and based on improving the arrangement of sipes provided in the middle land, etc., it has excellent noise performance while maintaining steering stability. The main purpose is to provide a pneumatic tire that can be used.

  In the tread portion, the shoulder main groove extending continuously in the tire circumferential direction at the tread end side and the center main groove extending continuously in the tire circumferential direction on the tire equator side than the shoulder main groove are provided in the tread portion. A pneumatic tire in which a middle land portion between the shoulder main groove and the center main groove is divided, wherein the tread portion is designated in a vehicle mounting direction, and the middle land portion Includes an outer middle land portion positioned outside the vehicle when the vehicle is mounted and an inner middle land portion positioned inside the vehicle when the vehicle is mounted. Each of the outer middle land portion and the inner middle land portion has a tire circumference. A middle vertical sipe extending continuously in the direction and a plurality of middle horizontal sipe extending in the tire axial direction are provided, the middle horizontal sipe having one end communicating with the center main groove and the other end A pitch interval P2 in the tire circumferential direction of the inner middle sipe provided on the outer middle land portion includes a plurality of inner middle sipe ending on the center main groove side with respect to the middle vertical sipe. It is larger than the pitch interval P1 in the tire circumferential direction of the inner middle horizontal sipe provided in the land portion.

  In the pneumatic tire of the present invention, the pitch interval P2 is preferably 1.70 to 1.85 times the pitch interval P1.

  In the pneumatic tire according to the aspect of the invention, it is preferable that the inner middle horizontal sipe includes a first inner middle horizontal sipe having a depth greater than at least a part of the middle vertical sipe.

  In the tire of the present invention, it is preferable that the inner middle horizontal sipe includes a second inner middle horizontal sipe extending in the tire axial direction at the same depth as or shallower than the middle vertical sipe.

  In the tire of the present invention, the inner middle horizontal sipe includes a second inner middle horizontal sipe extending in the tire axial direction at a depth equal to or shallower than the middle vertical sipe, and the first inner middle horizontal sipe and the second inner sipe. The middle lateral sipes are preferably provided alternately in the tire circumferential direction.

  The middle land portion of the pneumatic tire of the present invention is provided with a middle vertical sipe extending continuously in the tire circumferential direction and a plurality of middle horizontal sipes extending in the tire axial direction. The middle land portion provided with such a sipe is appropriately deformed when a contact pressure is applied. For this reason, at the time of straight running of the tire, generation of standing waves in the shoulder main groove and the center main groove is suppressed, and thus air column resonance noise is suppressed. In addition, when the above-described middle vertical sipe and middle horizontal sipe are subjected to ground pressure on the middle land portion, the sipe walls facing each other come into contact with each other. For this reason, the excessive deformation | transformation of a middle land part is suppressed and by extension, steering stability is maintained.

  The middle horizontal sipe includes a plurality of inner middle sipe that have one end communicating with the center main groove and the other end terminating on the side of the center main groove with respect to the middle vertical sipe. Such an inner middle horizontal sipe promotes deformation of the side wall of the middle land portion on the center main groove side while maintaining the rigidity of the middle land portion. Thereby, the generation of a standing wave in the center main groove that causes a large air column resonance is suppressed.

  The inner middle transverse sipe includes a first inner middle transverse sipe having at least a portion of a depth greater than the middle longitudinal sipe. Such a first inner middle lateral sipe is useful for irregularly deforming the side wall of the middle land portion when the tire is traveling straight ahead. For this reason, the air column resonance in the center main groove is further suppressed, and as a result, excellent noise performance is exhibited.

It is an expanded view of the tread part of the pneumatic tire of one embodiment of the present invention. FIG. 2 is an enlarged view of an inner middle land portion and an outer middle land portion of FIG. 1. (A) is the sectional view on the AA line of the 1st inner middle horizontal sipe of FIG. 2, (b) is the sectional view on the BB line of the 2nd inner middle horizontal sipe of FIG. ) Is a cross-sectional view of the outer middle horizontal sipe along line CC. It is an enlarged view of the outer side shoulder land part of FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a development view of a tread portion 2 of a pneumatic tire (hereinafter sometimes simply referred to as “tire”) 1 of the present embodiment. The pneumatic tire 1 of this embodiment is suitably used for, for example, a passenger car.

  The tread portion 2 of the present embodiment includes, for example, a tread pattern in which the mounting direction to the vehicle is specified. The direction of mounting on the vehicle is displayed by, for example, characters or marks on a sidewall (not shown) or the like. In FIG. 1, the left side corresponds to the inside of the vehicle, and the right side corresponds to the outside of the vehicle.

  By specifying the direction of mounting on the vehicle, the tread portion 2 has an inner tread end Te1 positioned on the inner side of the vehicle when the vehicle is mounted and an outer tread end Te2 positioned on the outer side of the vehicle when mounted on the vehicle. .

  Each of the tread ends Te1 and Te2 is a flat surface with a normal load applied to a normal tire 1 which is assembled with a normal rim (not shown) and filled with a normal internal pressure and is not loaded, and a camber angle of 0 °. This is the contact position on the outermost side in the tire axial direction when the contact is made on the ground.

  The “regular rim” is a rim defined for each tire in the standard system including the standard on which the tire is based. For example, “Standard Rim” for JATMA, “Design Rim” for TRA, For ETRTO, "Measuring Rim".

  “Regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. “JAMATA” is the “highest air pressure”, TRA is the table “TIRE LOAD LIMITS AT” The maximum value described in “VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” for ETRTO.

  “Regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based. “JATMA” is “Maximum load capacity”, TRA is “TIRE LOAD LIMITS” The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”, “LOAD CAPACITY” in the case of ETRTO.

  The tread portion 2 of the tire 1 is provided with a plurality of main grooves 3 extending continuously in the tire circumferential direction and land portions 4 divided into the main grooves 3.

  Each main groove 3 of the present embodiment extends linearly in the tire circumferential direction, for example. Each main groove 3 may extend in, for example, a zigzag shape or a wave shape. The main groove 3 includes, for example, a shoulder main groove 5 provided on the inner tread end Te1 side or the outer tread end Te2 side, and a center main groove 6 provided on the tire equator C side with respect to the shoulder main groove 5. Yes.

  The shoulder main groove 5 includes, for example, an inner shoulder main groove 5A provided on the inner tread end Te1 side and an outer shoulder main groove 5B provided on the outer tread end Te2 side.

  The center main groove 6 is provided, for example, between the inner shoulder main groove 5A and the outer shoulder main groove 5B. One center main groove 6 of this embodiment is provided on the tire equator C, for example. One center main groove 6 may be provided on each side of the tire equator C, for example.

  The groove width W1 of each main groove 3 of the present embodiment is desirably 3.0 to 7.0% of the tread ground contact width TW, for example. In the case of a pneumatic tire for passenger cars, the groove depth of each main groove 3 is preferably 5.0 to 12.0 mm, for example. The tread contact width TW is a distance in the tire axial direction between the inner tread end Te1 and the outer tread end Te2 of the tire 1 in the normal state.

  By providing the main groove 3 described above, as the land portion 4, for example, a middle land portion 7 between the shoulder main groove 5 and the center main groove 6, and a shoulder land portion on the outer side in the tire axial direction of the shoulder main groove 5. 8 is divided.

  The middle land portion 7 includes, for example, an inner middle land portion 7A between the inner shoulder main groove 5A and the center main groove 6 and an outer middle land portion 7B between the outer shoulder main groove 5B and the center main groove 6. Contains.

  FIG. 2 shows an enlarged view of the inner middle land portion 7A and the outer middle land portion 7B. As shown in FIG. 2, the middle land portion 7 is provided with a middle vertical sipe 10 that extends continuously in the tire circumferential direction and a plurality of middle lateral sipes 11 that extend in the tire axial direction. In this specification, “sipe” means a cut having a width of 1.5 mm or less, and is distinguished from a drainage groove having a larger width. In the middle land portion 7 of the present embodiment, for example, a groove having a width larger than that of the middle vertical sipe 10 and the middle horizontal sipe 11 is not provided. As a more desirable aspect, the middle land portion 7 of the present embodiment is a rib that extends continuously in the tire circumferential direction without being divided by the middle lateral sipe 11.

  The middle land portion 7 provided with such a sipe is appropriately deformed by utilizing the width of the sipe when a ground pressure acts. For this reason, at the time of straight running of the tire, generation of standing waves in the shoulder main groove 5 and the center main groove 6 is suppressed, and thus air column resonance noise is suppressed. On the other hand, when the above-described middle vertical sipe 10 and middle horizontal sipe 11 are subjected to ground pressure on the middle land portion 7, the sipe walls facing each other come into contact with each other. For this reason, the excessive deformation | transformation of the middle land part 7 is suppressed and by extension, steering stability is maintained.

  The middle vertical sipe 10 is provided, for example, at the center of the middle land portion 7 in the tire axial direction. The middle vertical sipe 10 of the present embodiment extends linearly along the tire circumferential direction, for example. Such a middle vertical sipe 10 is useful for suppressing uneven wear of the middle land portion 7. The middle vertical sipe 10 may be, for example, a wave or zigzag extending in the tire circumferential direction.

  The depth of the middle vertical sipe 10 is, for example, 3.0 to 4.5 mm. The middle vertical sipe 10 of this embodiment extends in the tire circumferential direction at a certain depth.

  The middle horizontal sipe 11 includes an inner middle horizontal sipe 12 and an outer middle horizontal sipe 13. Each of the inner middle horizontal sipe 12 and the outer middle horizontal sipe 13 of the present embodiment is provided in plural in the tire circumferential direction.

  The inner middle horizontal sipe 12 has one end communicating with the center main groove 6 and the other end terminating on the center main groove 6 side with respect to the middle vertical sipe 10. The inner middle lateral sipe 12 promotes deformation of the side wall of the middle land portion 7 on the side of the center main groove 6 while maintaining the rigidity of the middle land portion 7. Thereby, generation | occurrence | production of the stationary wave in the center main groove 6 which causes air column resonance sound is suppressed.

  The inner middle lateral sipe 12 is inclined with respect to the tire axial direction, for example. Specifically, the angle θ1 of the inner middle horizontal sipe 12 with respect to the tire axial direction is, for example, 30 to 45 °. When the sipe walls facing each other come into contact with each other, the inner middle lateral sipe 12 partially deforms the side wall of the middle land portion 7 in the tire axial direction, and further suppresses generation of a standing wave in the center main groove 6. To do.

  As a desirable mode, the inner middle lateral sipe 12 is smoothly curved convexly on one side or the other side in the tire circumferential direction.

  The length L1 of the inner middle horizontal sipe 12 in the tire axial direction is, for example, 0.35 to 0.45 times the width W2 of the middle land portion 7 in the tire axial direction. Such an inner middle lateral sipe 12 exhibits the above-described effects while maintaining steering stability.

  The inner middle horizontal sipe 12 provided in the inner middle land portion 7A includes a first inner middle horizontal sipe 15 and a second inner middle horizontal sipe 16 having different bottom shapes.

  FIG. 3A shows a cross-sectional view taken along line AA of the first inner middle horizontal sipe 15 of FIG. As shown in FIG. 3A, the first inner middle horizontal sipe 15 has at least a part of a depth d2 that is larger than the depth d1 of the middle vertical sipe 10. Such a first inner middle lateral sipe 15 is useful for irregularly deforming the side wall of the inner middle land portion 7A during straight traveling of the tire. For this reason, the air column resonance sound of the center main groove 6 is further suppressed, and as a result, excellent noise performance is exhibited.

  The first inner middle horizontal sipe 15 of the present embodiment includes, for example, a first portion 17 having the depth d2 and a second portion 18 having a depth d3 smaller than the first portion 17.

  The depth d2 of the first portion 17 is, for example, preferably 1.20 times or more, more preferably 1.45 times or more, preferably 1.70 times or less, more preferably 1.70 times or more the depth d1 of the middle vertical sipe 10. Is 1.60 times or less. Such a first portion 17 is useful for balancing steering stability and noise performance in a well-balanced manner.

  The second portion 18 is provided, for example, between the first portion 17 and the center main groove 6. The length of the second portion 18 in the tire axial direction is, for example, smaller than the length of the first portion 17 in the tire axial direction.

  The depth d3 of the second portion 18 is, for example, 0.9 to 1.1 times the depth d1 of the middle vertical sipe 10. As a desirable mode, the depth d3 of the second portion 18 of the present embodiment is the same as the depth d1 of the middle vertical sipe 10. Such a second portion 18 serves to make the progress of wear uniform between the central portion of the inner middle land portion 7A and the edge on the center main groove 6 side.

  As shown in FIG. 2, the second inner middle horizontal sipe 16 is inclined in the same direction as the first inner middle horizontal sipe 15, for example. As a desirable mode, the second inner middle transverse sipe 16 extends along the first inner middle transverse sipe 15. As a more desirable mode, the second inner middle horizontal sipe 16 has the same shape as the first inner middle horizontal sipe 15 in a tread plan view.

  FIG. 3B shows a cross-sectional view of the second inner middle horizontal sipe 16 shown in FIG. As shown in FIG. 3B, the second inner middle horizontal sipe 16 has, for example, a constant depth d4. The depth d4 of the second inner middle horizontal sipe 16 is preferably the same as or smaller than the depth d1 of the middle vertical sipe 10, for example.

  As shown in FIG. 2, as a desirable mode, the first inner middle lateral sipe 15 and the second inner middle lateral sipe 16 of the present embodiment are alternately provided in the tire circumferential direction. The first inner middle lateral sipe 15 and the second inner middle lateral sipe 16 further irregularly deform the side wall of the inner middle land portion 7A to suppress generation of a standing wave in the center main groove 6. To help.

  The inner middle horizontal sipe 12 provided in the outer middle land portion 7B has a certain depth, for example, like the second inner middle horizontal sipe 16 (shown in FIG. 3B).

  In the outer middle land portion 7B of the present embodiment, only the inner middle lateral sipe 12 having the above-described shape is provided in the tire circumferential direction.

  The pitch interval P2 in the tire circumferential direction of the inner middle lateral sipe 12 provided in the outer middle land portion 7B is larger than the pitch interval P1 in the tire circumferential direction of the inner middle lateral sipe 12 provided in the inner middle land portion 7A. Is desirable. Specifically, the pitch interval P2 is preferably 1.70 times or more, more preferably 1.75 times or more, preferably 1.85 times or less, more preferably 1.80 times the pitch interval P1. It is as follows. Such an arrangement of the inner middle lateral sipe 12 increases the rigidity of the outer middle land portion 7B, and, for example, helps increase the response of the steering wheel during turning.

  For example, the outer middle horizontal sipe 13 has one end communicating with the shoulder main groove 5 and the other end terminating on the shoulder main groove 5 side with respect to the middle vertical sipe 10. Such an outer middle horizontal sipe 13 is useful for suppressing the generation of a standing wave in the shoulder main groove 5 while maintaining the rigidity of the middle portion of the middle land portion 7.

  The outer middle horizontal sipe 13 is, for example, convex and smoothly curved on one side or the other side in the tire circumferential direction. As a desirable mode, it is desirable that the outer middle horizontal sipe 13 is connected to a virtual extension line obtained by smoothly extending the inner middle horizontal sipe 12, for example. Such an outer middle horizontal sipe 13 can make the progress of wear uniform between the edge of the middle land portion 7 on the center main groove 6 side and the edge of the shoulder main groove 5 side.

  FIG. 3C shows a cross-sectional view taken along line CC of the outer middle horizontal sipe 13 of FIG. As shown in FIG. 3C, the outer middle horizontal sipe 13 has, for example, a depth d5 larger than that of the middle vertical sipe 10 at least in part. Such an outer middle lateral sipe 13 facilitates deformation of the outer middle land portion 7B on the outer side in the tire axial direction, and serves to suppress generation of a standing wave in the shoulder main groove 5.

  The outer middle lateral sipe 13 includes, for example, a first portion 21 having the above-described depth d5 and a second portion 22 having a depth d6 smaller than the first portion 21.

  The depth d5 of the first portion 21 of the outer middle horizontal sipe 13 is, for example, 1.45 to 1.55 times the depth d1 of the middle vertical sipe 10. As a desirable mode, the depth d5 of the first portion 21 of the outer middle horizontal sipe 13 is the same as the depth d2 of the first portion 17 of the first inner middle horizontal sipe 15 (shown in FIG. 3A). Such an outer middle lateral sipe 13 is useful for suppressing uneven wear of the middle land portion 7.

  The second portion 22 of the outer middle horizontal sipe 13 is provided between the first portion 21 and the shoulder main groove 5, for example. The length of the second portion 22 in the tire axial direction is, for example, smaller than the length of the first portion 21 along the tire axial direction.

  The depth d6 of the second portion 22 of the outer middle horizontal sipe 13 is, for example, the depth d1 of the middle vertical sipe 10 or the depth d3 of the second portion 18 of the first inner middle sipe 15 (FIG. 3A). It is desirable to be smaller than the following. Specifically, the depth d6 of the second portion 22 of the outer middle horizontal sipe 13 is, for example, 0.65 to 0.75 times the depth d3 of the second portion 18 of the first inner middle horizontal sipe 15. . Such an outer middle horizontal sipe 13 can increase the rigidity of the middle land portion 7 on the outer side in the tire axial direction, and thus maintain steering stability.

  As shown in FIG. 1, the shoulder land portion 8 includes, for example, an inner shoulder land portion 8A between the inner shoulder main groove 5A and the inner tread end Te1, and an outer shoulder main groove 5B and the outer tread end Te2. The outer shoulder land portion 8B.

  FIG. 4 shows an enlarged view of the outer shoulder land portion 8 </ b> B as a diagram for explaining the configuration of the shoulder land portion 8. As shown in FIG. 4, for example, a shoulder lug groove 25 and a shoulder sipe 26 are provided in the shoulder land portion 8.

  The shoulder lug groove 25 extends, for example, in the tire axial direction from the tread end side and terminates in the shoulder land portion 8. Such a shoulder lug groove 25 reduces a pumping sound and by extension improves noise performance.

  The angle θ2 of the shoulder lug groove 25 with respect to the tire axial direction is, for example, 0 to 15 °. As a desirable mode, the angle θ2 gradually increases toward the inner side in the tire axial direction. Such a shoulder lug groove 25 is useful for suppressing uneven wear near the inner end thereof.

  For example, one or two shoulder sipes 26 are provided between the shoulder lug grooves 25 and 25 adjacent in the tire circumferential direction.

  The shoulder sipe 26 is, for example, a closed sipe whose both ends are terminated in the shoulder land portion 8. Such a shoulder sipe 26 is useful for relaxing the impact sound when the shoulder land portion 8 is grounded and improving the noise performance.

  For example, the inner end 26i of the shoulder sipe 26 is preferably located on the inner side in the tire axial direction than the inner end 25i of the shoulder lug groove 25. Such a shoulder sipe 26 can relieve the distortion of the tread between the shoulder lug groove 25 and the shoulder main groove 5 and suppress uneven wear.

  The outer shoulder land portion 8B has a plain portion 27 in which no groove and sipe are arranged between the outer shoulder main groove 5B, the shoulder lug groove 25, and the shoulder sipe 26. Such a plane portion 27 can enhance the response of the handle when turning.

  As shown in FIG. 1, as a desirable mode, in addition to the shoulder lug groove 25 and the shoulder sipe 26 described above, the inner shoulder land portion 8A is provided between the inner end 25i of the shoulder lug groove 25 and the inner shoulder main groove 5A. A connecting sipe 28 is provided to communicate with each other. Such a connection sipe 28 can promote deformation of the side wall of the inner shoulder land portion 8A, and can suppress generation of a standing wave in the inner shoulder main groove 5A.

  Although the pneumatic tire of the present invention has been described in detail above, the present invention is not limited to the specific embodiment described above, and is implemented with various modifications.

A pneumatic tire of size 185 / 60R15 having the basic tread pattern of FIG. 1 and having the first inner middle horizontal sipe shown in FIG. 3A was made on the basis of the specifications of Table 1. As a comparative example, a pneumatic tire having the basic pattern of FIG. 1 and having all the inner middle horizontal sipe formed with the same depth as the middle vertical sipe was manufactured as a prototype. Each test tire was tested for noise performance and wet performance. The common specifications and test methods for each test tire are as follows.
Rims: 15 × 5.0J
Tire internal pressure: 230kPa
Test vehicle: displacement 1300cc, front-wheel drive vehicle Test tire mounting position: all wheels

<Noise performance>
Vehicle interior noise was measured when traveling on a dry asphalt road surface at a speed of 60 km / h with the test vehicle. Vehicle interior noise was measured with a microphone located at the head of the driver's seat. The results are shown as an index with the in-vehicle noise of the comparative example as 100. The smaller the value, the better the noise performance.

<Steering stability>
The driving stability of the test vehicle when traveling on an asphalt circuit was evaluated by the driver's sensuality. A result is a score which makes a comparative example 100, and shows that steering stability is excellent, so that a numerical value is large.
The test results are shown in Table 1.

  As a result of the test, it was confirmed that the pneumatic tires of the examples exhibited excellent noise performance while maintaining steering stability.

2 tread portion 5 shoulder main groove 6 center main groove 7 middle land portion 7A inner middle land portion 7B outer middle land portion 10 middle vertical sipe 11 middle horizontal sipe 12 inner middle horizontal sipe

Claims (3)

By providing a shoulder main groove extending continuously in the tire circumferential direction at the tread end side in the tread portion and a center main groove extending continuously in the tire circumferential direction on the tire equator side than the shoulder main groove, A pneumatic tire in which a middle land portion between the shoulder main groove and the center main groove is divided,
The middle land portion is a rib extending continuously in the tire circumferential direction,
The tread portion is designated for mounting on the vehicle,
The middle land portion includes an outer middle land portion located outside the vehicle when the vehicle is mounted, and an inner middle land portion located inside the vehicle when the vehicle is mounted,
Each of the outer middle land portion and the inner middle land portion is provided with a middle vertical sipe extending continuously in the tire circumferential direction and a plurality of middle horizontal sipes extending in the tire axial direction.
The middle horizontal sipe includes a plurality of inner middle horizontal sipes having one end communicating with the center main groove and the other end terminating on the center main groove side with respect to the middle vertical sipe,
The pitch interval P2 in the tire circumferential direction of the inner middle sipe provided in the outer middle land portion is larger than the pitch interval P1 in the tire circumferential direction of the inner middle sipe provided in the inner middle land portion.
Pneumatic tire.   The pneumatic tire according to claim 1, wherein the pitch interval P2 is 1.70 to 1.85 times the pitch interval P1. The pneumatic tire according to claim 1 or 2, wherein the inner middle lateral sipe is inclined at an angle of 30 to 45 ° with respect to a tire axial direction .

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