JP4499464B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire with improved steering stability and wet performance without reducing noise performance.

  In a pneumatic tire, a main groove continuous in the tire circumferential direction is formed on the tread surface to ensure drainage. Since the vicinity of the bottom of the main groove on the outside of the vehicle is easily deformed, the steering stability may be lowered. Further, when the tire rotates and the tread comes in contact with the road surface, the air trapped in the main groove and the road surface is compressed and flows out along the main groove. At this time, external noise called air column resonance is easily generated due to a rapid flow of air. If the width of the main groove is narrowed, the air column resonance noise is reduced and the noise outside the vehicle can be reduced. However, since the volume of the main groove is reduced, the drainage performance is lowered and the wet performance is deteriorated.

In the pneumatic tire disclosed in Patent Document 1, the side wall of the main groove is formed by slopes having different slope angles, and the slope of the slope on the groove bottom side is further increased. As a result, deformation near the bottom of the main groove on the vehicle outer side is suppressed, and steering stability is improved. Further, in the pneumatic tire disclosed in Patent Document 2, convex portions that are continuous in the circumferential direction are provided on the side wall of the main groove to suppress abrupt air flow and reduce outside noise.
JP 60-203505 A Japanese Patent Laid-Open No. 06-179308

  However, in the pneumatic tire of Patent Document 1, drainage is ensured, but the ribs adjacent to the main grooves and the base portions of the blocks are not sufficiently reinforced compared to the case where the convex portions are provided. The effect of suppressing the deformation of the ribs and blocks against the lateral force was insufficient. In the pneumatic tire of Patent Document 2, since the cross section of the convex portion in the tire width direction has a stepped shape, the main groove volume rapidly decreases as wear progresses. As a result, the wet performance may be extremely deteriorated. Thus, it has been difficult to achieve both steering stability and vehicle exterior noise reduction while ensuring drainage.

  An object of the present invention is to improve steering stability and wet performance without reducing noise performance.

As a result of intensive studies to solve the above-mentioned problems, the invention according to claim 1 is directed to a pneumatic tire having a main groove continuous in the tire circumferential direction carved on the tread surface, and the vehicle in the tire width direction of the main groove. A ridge that protrudes from the outer side wall and extends in the tire circumferential direction, the ridge includes alternating narrow portions and wide portions, and the top surface of the ridge extends from the side wall of the main groove to the main groove. Inclined so that the height decreases inward ,
The width W1 of the narrow portion is more than 0% and less than 40% of the groove width W of the main groove, and the width W2 of the wide portion is 40% or more and 90% or less of the groove width W of the main groove. Yes, the depth D1 from the tread to the protrusion on the side wall of the main groove is 20% or more and less than 70% of the main groove depth D, and the depth D2 from the tread to the ridge line of the protrusion Is a pneumatic tire that is 70% or more and 100% or less of the main groove depth D. According to a second aspect of the present invention, there is provided a pneumatic tire including a main groove carved on a tread surface and continuous in a tire circumferential direction. Provided with ridges, the ridges are alternately provided with narrow portions and wide portions, and the top surfaces of the ridges are inclined so that the height decreases from the side walls of the main grooves to the inside of the main grooves. And
The width W1 of the narrow portion is 0% of the groove width W of the main groove, the width W2 of the wide portion is 40% or more and 90% or less of the groove width W of the main groove, The depth D1 from the tread to the protrusion on the side wall is 20% or more and less than 70% of the main groove depth D, and the depth D2 from the tread to the ridge line of the protrusion is the main groove depth. The pneumatic tire was 70% or more and 100% or less of D.

  First, since the base part of the land part (rib or block) adjacent to the main groove is reinforced by the ridge protruding from the side wall outside the vehicle in the tire width direction of the main groove, deformation of the land part against lateral force is suppressed. Is done. As a result, an effective contact area is ensured and steering stability is improved.

  Since the ridge has a narrow portion, a decrease in the volume of the main groove can be minimized as compared with the conventional case, and drainage performance is improved. In addition, since the top surface of the ridge is inclined so that the height decreases from the side wall of the main groove to the inside of the main groove, the volume of the main groove does not rapidly decrease even when wear progresses. As a result, sufficient drainage can be secured even after the middle period of wear.

  When the tire rotates and the tread contacts the road surface, the air trapped in the main groove and the road surface is compressed and flows out along the main groove, but the width of the main groove 1 is narrowed by the protrusions. The rapid air flow is suppressed and air column resonance noise is reduced. In particular, the sudden outflow of air can be effectively suppressed by the portion where the width of the main groove is narrower by the wide portion.

  By setting the width W1 of the narrow portion and the width W2 of the wide portion within the above ranges, it is possible to reduce vehicle exterior noise without sacrificing steering stability and wet performance. By making D1 and D2 into the said range, the volume of a main groove does not fall rapidly after the middle stage of wear, and drainage is ensured.

  The invention according to claim 3 is the pneumatic tire according to claim 1 or 2, wherein there are two or more wide portions in a tire circumferential direction length range of a contact surface in a state of normal internal pressure and normal load.

  From the viewpoint of reducing the air column resonance noise, if there are two or more wide portions in the range of the tire circumferential direction length of the contact surface in the state of normal internal pressure and normal load, the rapid air flow is more effectively suppressed and the air flow is suppressed. Column resonance noise is reduced.

The pneumatic tire of the present invention includes a ridge that protrudes from a side wall on the vehicle outer side of the main groove in the tire width direction and that is continuous or arranged in the tire circumferential direction, and the ridge alternately includes a narrow portion and a wide portion. The top surface of the ridge is inclined so as to decrease in height from the side wall of the main groove to the inside of the main groove. Noise reduction can be achieved at the same time.

  Hereinafter, embodiments of a pneumatic tire according to the present invention will be described with reference to the drawings. FIG. 1A is a pattern development view showing a pneumatic tire according to the present invention, which is an asymmetric pattern. The tread is formed with a main groove 1 extending in the tire circumferential direction R and a lateral groove 2 communicating with the main groove 1 to form ribs 3 and blocks 4. A protrusion 5 extending in the tire circumferential direction R is provided on the side wall of the main groove 1 outside the vehicle. The dotted line indicates the ridge line 6 of the protrusion 5.

  This will be further described with reference to an enlarged pattern diagram shown in FIG. The width of the protrusion 5 is not constant, and has a narrow portion 5a and a wide portion 5b. The width of the narrow portion 5a is W1, and the width of the wide portion 5b is W2. The narrow portions 5a and the wide portions 5b appear alternately, P is an interval (pitch) between the adjacent wide portions 5a and the narrow portions 5b, and the interval P may or may not be constant. .

  1C is a cross-sectional view taken along the line A1-A2 of FIG. 1B, and shows a cross section of the wide portion 5b. FIG. 1D is a cross-sectional view taken along the line B1-B2 of FIG. The cross section of the part 5a is shown. The depth from the tread T to the ridge 5 on the side wall of the main groove 1 is D1, and the depth from the tread T to the ridge line 6 of the ridge 5 is D2. Since D2 is larger than D1, the top surface 7 of the protrusion 5 is inclined so that the height decreases from the side wall of the main groove 1 to the inside of the main groove 1.

  Since the ridge 5 reinforces the root portion of the rib 3 adjacent to the main groove 1, deformation of the rib 3 against lateral force or the like is suppressed. As a result, an effective ground contact area is ensured and steering stability is improved.

  Since the protrusion 5 is provided with the narrow part 5a, the volume of the main groove 1 is sufficiently ensured compared with the conventional case, so that drainage is improved. Since the top surface 7 of the ridge 5 is inclined so that the height decreases from the side wall of the main groove 1 to the inside of the main groove 1, the volume of the main groove 1 rapidly decreases even as wear progresses. There is no. As a result, sufficient drainage can be secured even after the middle period of wear.

  When the tire rotates and the tread contacts the road surface, the air trapped in the main groove 1 and the road surface is compressed and flows out along the main groove 1, but the width of the main groove 1 is narrowed by the protrusion 5. The rapid air flow at this time is suppressed, and the air column resonance noise is reduced. In particular, the sudden outflow of air can be effectively suppressed by the portion where the width of the main groove 1 is narrower by the wide portion 5b. Therefore, it is preferable that there are two or more wide portions 5b in the range of the tire circumferential direction length of the contact surface in the state of normal internal pressure and normal load.

  The width W1 of the narrow portion 5a is 0% or more and less than 40% of the groove width W of the main groove 1, and the width W2 of the wide portion 5b is 40% or more and 90% or less of the groove width W of the main groove 1. It is preferable that If W1 is 40% or more of W, the extent to which the volume of the main groove 1 is secured by the narrow portion 5a is so small that drainage performance may not be secured. When W2 exceeds 90% of W, the volume of the main groove 1 becomes small, and the drainage performance may not be ensured. Here, as shown in FIG. 1A, when the width of the main groove 1 changes, the width W of the main groove 1 refers to the width of the narrowest portion.

  The depth D1 from the tread T to the ridge 5 on the side wall of the main groove 1 is 20% or more and less than 70% of the depth D of the main groove 1, and the depth D2 from the tread T to the ridge line 6 of the ridge 5 Is preferably 70% or more and 100% or less of the depth D of the main groove 1. When D1 is 70% or more of D, the reinforcement of the root portion of the rib 3 adjacent to the main groove 1 may not be sufficient. If D1 is less than 20 of D, the volume of the main groove 1 may be reduced and the drainage performance may not be ensured. When D2 is less than 70 of D, the slope of the top surface 7 of the ridge 5 is gentle, and the volume of the main groove 1 may be suddenly reduced.

  In the symmetrical pattern shown in FIG. 2, since either side can be the vehicle outer side, the protrusions 5 may be provided on both sides with respect to the center line CL. Moreover, although the example which provided the protrusion on the side wall of the main groove which forms a rib was shown, even if it provides a protrusion on the side wall of the main groove which forms a block, the same effect is acquired.

  Pneumatic tires according to Examples and Conventional Examples were prototyped and performance evaluations were performed. The embodiment has the pattern shown in FIG. 1A, and the dimensions of the protrusions are as shown in Table 1. Conventional examples 1 and 2 have the patterns shown in FIGS. 3A and 3B, respectively, and the shapes of the main grooves are as shown in FIGS. 3C and 3D. In Conventional Example 1, a ridge is provided on the side wall of the main groove, and the width and height of the ridge are constant. In Conventional Example 2, the side wall of the main groove is composed of slopes having different inclination angles, the inclination angle on the tread side is 5 °, and the inclination angle on the groove bottom side is 30 °. In any tire, the width W of the main groove is 8 mm, and the depth D of the main groove is 8 mm. Table 1 shows the main groove cross-sectional area of each tire as an index with the main groove cross-sectional area of Conventional Example 1 taken as 100. However, in the embodiment, since the cross-sectional area is not constant, the average value is used.

  The tire size was 205 / 55R16, the rim size was 16 × 6.5-J, and the air pressure was 210 kPa. The tire was mounted on a domestic FF sedan type passenger car, and performance evaluation was performed. The results are shown in Table 1. Steering stability was expressed as an index of feeling test for two drivers on dry and wet roads. The hydroplaning performance was expressed as an exponent of the reciprocal of the speed at which hydroplaning occurred when the water traveled at a depth of 8 mm. The noise outside the vehicle was measured by measuring the sound pressure level when passing through a designated section at a speed of 60 km / h in accordance with the method specified in JASO C606, and the reciprocal was expressed as an index. All are represented by an index with Conventional Example 1 being 100, and the larger the value, the better the performance. Note that 50% wear means when the tread is worn by 50% of the depth of the main groove.

  According to Table 1, the steering stability of the tires of any of the examples is maintained substantially equal to that of Conventional Example 1. Since the top surface of the ridge is inclined, there is no sudden decrease in the main groove volume, and the hydroplaning performance at 50% wear is improved. In Example 1, the main groove volume is sufficiently secured, and the hydroplaning performance when new and 50% worn is improved. Although the hydroplaning performance was slightly inferior to that of the conventional example 2, the steering stability was not deteriorated, and both the steering stability and the hydroplaning performance could be achieved. Further, the noise outside the vehicle is also maintained at the same level as that of the conventional example 1 without deterioration.

(A) is a pattern development view showing an embodiment of a pneumatic tire according to the present invention, (b) is an enlarged view of the pattern, (c) is a sectional view taken along line A1-A2 of (a), and (d) is (a). It is B1-B2 sectional drawing of. It is a pattern development view showing other embodiments of a pneumatic tire concerning the present invention. (A) And (b) is a pattern development view of the pneumatic tire which concerns on the prior art examples 1 and 2, (c) and (d) is a figure which shows the cross section of each main groove.

Explanation of symbols

1 main groove 2 lateral groove 3 rib 4 block 5 ridge 6 ridge line of ridge 7 top surface of ridge

Claims (3)

In a pneumatic tire provided with a main groove continuous in the tire circumferential direction carved on the tread surface, the pneumatic tire includes a protrusion continuously protruding in the tire circumferential direction protruding from a vehicle outer side wall of the main groove in the tire width direction. The narrow portion and the wide portion are alternately provided, and the top surface of the protrusion is inclined so that the height decreases from the side wall of the main groove to the inside of the main groove ,
The width W1 of the narrow portion is more than 0% and less than 40% of the groove width W of the main groove, and the width W2 of the wide portion is 40% or more and 90% or less of the groove width W of the main groove. Yes, the depth D1 from the tread to the protrusion on the side wall of the main groove is 20% or more and less than 70% of the main groove depth D, and the depth D2 from the tread to the ridge line of the protrusion Is a pneumatic tire that is 70% or more and 100% or less of the main groove depth D. In a pneumatic tire having a main groove continuous in the tire circumferential direction carved on the tread surface, the pneumatic tire includes a protrusion disposed in a tire circumferential direction protruding from a side wall outside the vehicle in the tire width direction of the main groove, and the protrusion Is provided with alternating narrow and wide portions, the top surface of the ridge is inclined so that the height decreases from the side wall of the main groove to the inside of the main groove,
The width W1 of the narrow portion is 0% of the groove width W of the main groove, the width W2 of the wide portion is 40% or more and 90% or less of the groove width W of the main groove, The depth D1 from the tread to the protrusion on the side wall is 20% or more and less than 70% of the main groove depth D, and the depth D2 from the tread to the ridge line of the protrusion is the main groove depth. A pneumatic tire that is 70% or more and 100% or less of D.   The pneumatic tire according to claim 1 or 2, wherein there are two or more wide portions in a range of a tire circumferential direction length of a road surface in a state of normal internal pressure and normal load.

Images