JPH0288312A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To prevent heel and tow wear during running by providing a stepoff area in a wider groove near a kick-off end of the multiple blocks formed by multiple wider grooves in a tire road surface continuous in the peripheral direction. CONSTITUTION:Multiple blocks 7 are formed on the road surface 2 of a tire by multiple wider grooves 8, continuously extending in the peripheral direction. In the wider groove 3b near the kick-off end 17 of the external block 7 in the proximity of a shoulder edge 5, the stepoff area 9 where the external edge 9a in the radial direction is positioned internally in the radial direction from the sectional contour line 10 of a block. This makes the stepoff area 9 come in slide contact with the road surface during running so as to function as a sacrificial portion of uneven wear.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pneumatic tire in which a large number of blocks are defined by forming wide grooves such as main grooves and lateral grooves on a road surface.

Generally speaking, when a pneumatic tire with many blocks on its tread is run and the circumferential shearing force acting on each block is measured when it touches the ground, the driving direction shearing force is on the treading side of each block, and on the other hand. A shearing force in the braking direction acts on the kicking-off side, and the absolute value of these shearing forces is maximum near the stepping-in end and the kicking-off end. Here, the wear rate of the road surface receiving shear force in the braking direction is significantly faster than the wear rate of the road surface receiving shear force in the driving direction, so when driving,
Only the region receiving shearing force in the braking direction, ie, the kicking side of each block, is worn, and the amount of wear increases toward the kicking end, resulting in so-called heel-and-toe wear.

Conventionally, in order to prevent such heel-and-toe wear, for example, a large number of sizes are formed around each block to reduce the bending rigidity of each block.

However, although these products can prevent heel-and-toe wear to some extent, the effect is not sufficient.

An object of the present invention is to provide a pneumatic tire that can reliably prevent heel-and-toe wear of blocks defined on a road surface.

Such a purpose is to provide a pneumatic tire in which a large number of blocks are defined by forming wide grooves on the tread surface, at least in the wide groove near the kicking end of the block, so that the outer end surface in the radial direction is located in the cross section of the block. A step area is provided which is located radially inward from the contour line and where the outer end surface in the radial direction comes into contact with the road surface when reaching the tread surface area, and when driving, the step area slides into contact with the road surface as an uneven wear victim part. This can be achieved by making it work.

When a pneumatic tire having blocks on its tread is run, a shearing force in the braking direction acts on the kicking side of each block when the tire touches the ground, and only the kicking side tends to wear out. Here, the outer end surface in the radial direction of the step φ area provided in the wide groove near the kicking end of the block comes into contact with the road surface when reaching the tread area during the traveling, but the radial direction of this step area Since the outer end surface is located radially inward from the cross-sectional contour line of the block, the radial outer end surface of the stepped region slides into contact with the road surface while being dragged.

As a result, an extremely large shearing force in the direction of braking the displacement of the pneumatic tire is generated on the radially outer end surface of the stepped region, that is, in the braking direction. Here, since the total value of the shear forces in the driving and braking directions generated within a unit area is considered to be approximately constant, as mentioned above, a large shearing force in the braking direction is newly generated in a part of the unit area, that is, in the step area. When this occurs, the shearing force acting on the block near the step area (the block on the kicking side) is shifted up to the drive side as a result.

As a result, the shearing force acting on the kicking side of the block is in the driving direction, and the above-mentioned wear is reliably prevented. As a result, the wear of the block progresses almost uniformly on the stepping side and the kicking side, and uneven wear, that is, heel-and-toe wear, is reliably prevented.

1st Shift" Hereinafter, a first embodiment of the present invention will be described based on the drawings.

In Figure 1.2.3, 1 is a pneumatic radial tire that is installed on the driven wheels or idle wheels of passenger cars, trucks, buses, etc. The tread 2 of this tire 1 has a plurality of continuous tires extending in the circumferential direction. A main groove 3 is formed. These main grooves 3 include a pair of inner main grooves 3a arranged close to the tire equatorial plane 4 on both sides of the tire equatorial plane number, and a pair of inner main grooves 3a disposed close to the shoulder end 5 on both sides of the tire equatorial plane 4. A pair of outer main grooves 3b, and the inner main groove 3
a is bent in a zigzag shape, while the width of the outer main groove 3b increases and decreases in synchronization with the zigzag of the inner main groove 3a. Tread between the inner main grooves 3a 2. The tread surface 2 between the inner main groove 3a and the outer main groove 3b, and the tread surface 2 between the outer main groove 3b and the shoulder end 5 each have a plurality of lateral grooves Ela.
, 8b, 8c are formed, and these lateral grooves 6a, 6b,
θC is equally spaced apart in the circumferential direction and extends in the axial direction of the tire 1. These lateral grooves 6b and 8C are arranged in the same phase in the circumferential direction, and the lateral groove 6a and the lateral tII 48b are shifted in phase by 1/2 pitch in the circumferential direction. As a result, on the tread surface 2 between the inner main grooves 3a, the inner main grooves 3a
and the lateral grooves 8a define a plurality of inner blocks 7a that are equidistant # apart in the circumferential direction, and the inner main 11! I3a, the outer main groove 3b and the lateral groove 6b define a plurality of intermediate blow holes 7b equidistantly spaced apart in the circumferential direction, and furthermore, on the tread surface 2 between the outer main groove 3b and the shoulder end 5, A plurality of outer blocks 7C are defined by the outer main 1s3b and the lateral grooves 6c, which are equidistantly spaced apart in one circumferential direction. The aforementioned inner and outer main grooves 3a, 3b and lateral grooves 8a, 6b, 6c as a whole constitute a wide wide groove 8 that does not close even when touching the ground, and this wide groove 8 allows the tread 2 to have inner blocks 7a,
A large number of blocks 7 are defined, each consisting of an intermediate block 7b and an outer block 7c. In each of the outer main grooves 3b, a step region 8 having a similar shape to the intermediate block 7b and having a smaller area is formed at a position where the outer main groove 3b intersects the horizontal IElb, 8c, and these step regions 9 is the middle block 7b and the % side block 7C which are both separated by a predetermined distance from the middle block 7b and the outer block 7C.
They are independent from each other and are equidistant from each other in the circumferential direction. Here, the average circumferential length (if the circumferential length changes in the axial direction, the average value of the circumferential length) L of each stepped region 8 is 30 mm or more.

In addition, the average width (if the width changes in the circumferential direction, the average value of the width) B of each stepped region 9 is preferably 5 mm or more.The reason is that the average circumferential length L or the average width B
If at least one of them is less than the above value, the rigidity of the stepped region 9 will be reduced, and the function of the stepped region 8 as a victim of uneven wear will be reduced. Then, as in this embodiment, the width of the stepped region 9 is set to the middle, outer block 7b, ?
If the change is made so as to be maximum at the kicking end of c, the influence on the kicking side of these intermediate and outer blocks 7b and 7C will be large, and uneven wear can be reliably prevented. In this embodiment, the stepped region 8 is separated from the intermediate block 7b and the outer block 7c by a predetermined distance, and a wide groove remains between them. 9 and the outer block 7c may have a narrow groove or size that closes when it touches the ground, and a wide groove may remain in the other. It is located radially inward by a certain distance a from the cross-sectional contour line lO of block 7. Here, distance a
The radial outer end surfaces 9a of these stepped regions 9 contact the road surface together with the outer surface of the blower 7 when the tire 1 reaches the tread surface area as the tire 1 runs. One circumference connecting all the radially outer end surfaces 8a of the intermediate block 7b or the outer block 7
Since it is shorter than one circumferential length connecting c, the radially outer end surface 8
When the vehicle a contacts the ground, it slides into contact with the road surface and receives a large shearing force in the braking direction.

Next, the operation of the first embodiment of the present invention will be explained.

Now, assume that the tire 1 as described above is rotating and traveling in the direction of arrow A. At this time, when the block 7 reaches the tread surface area, that is, when it touches the road surface, a shearing force in the driving direction is generated on the stepping side, and a shearing force in the braking direction is generated on the kicking side. Absolute value is for each block
It reaches its maximum near the stepping-in end 16 and kicking-out end 17 of No.7. Here, since the wear rate of the parts receiving shear force in the braking direction is significantly faster than the wear rate of the parts receiving shear force in the driving direction, the parts receiving shear force in the braking direction, that is, the kicking of each block 7 Only the sides are going to wear out. Here, as described above, the shearing force in the braking direction has a maximum value near the kicking end 17, so wear progresses fastest near the kicking end 17 of each block 7. However, in this embodiment, the outer main #13 inside the outer main groove 3b
b and transverse groove eb.

6C, that is, near the kicking end 17 of each intermediate block 7b and the outer block 7C (stepping end 1
A step region 3 is provided in the step area (also near B), and the radially outer end surface 9a of each step region S is brought into contact with the road surface together with the outer surfaces of the intermediate block 7b and the outer block 7c when reaching the tread surface area. However, since the radially outer end surface 9a of each step region 9 is located radially inward from the cross-sectional contour line 10 of the intermediate block 7b and outer block 7c, the radially outer end surface 9a of the step region 8 is located on the road surface. They will come into sliding contact while being dragged by. When in contact with the road surface in this manner, an extremely large shearing force is generated on the radially outer end surface 9a of the stepped region 9 in the direction of braking the displacement of the tire l, that is, in the braking direction. Here, since the total value of the driving and braking direction shear forces generated within the unit area of the tread surface 2 of the tire l is considered to be approximately constant, as mentioned above, the total value of the shear force in the driving and braking directions is approximately constant. When an extremely large shearing force in the braking direction is newly generated on the radially outer end surface 9a, the influence of the shearing force in the braking direction spreads around the step region 8, and the intermediate block 7b and the outer block located near the step region 8 are affected. As a result, the shearing force near the kicking end 17 of 7C is shifted up to the drive side. This allows each intermediate block? b and the kicking side of the outer block 7C, especially the shearing force acting near the kicking end 17, which conventionally received a large shearing force in the braking direction, is now in the driving direction, and wear based on the shearing force in the braking direction is reliably prevented. be done.

On the other hand, the stepped region 9 wears out before the intermediate and outer blocks 7b and 7c due to the extremely large shearing force in the braking direction, and functions as a victim of uneven wear. Note that the influence of the shear force in the braking direction in the stepped region θ also spreads to the vicinity of the depression end IB of the intermediate block 7b and the outer block 7c, further increasing the shear force value in the driving direction in this area. Even if the value increases, since it is in the driving direction, the wear rate hardly changes.For this reason, the wear of the intermediate block 7b and the outer block 7c progresses almost uniformly on the stepping side and the kicking side. Uneven wear, i.e.
Heel and toe wear is reliably prevented.

Next, a test example will be explained. At the beginning of this test, a comparison tire 1 with a tread pattern as shown in FIGS. 4 and 5 and a test tire 1 to which the present invention was applied with a tread pattern as shown in FIGS. 6 and 7.8 were used. 2 and was explained in the first embodiment. That is, a test tire 3 having a tread pattern shown in FIG. 1.2.3 was prepared. Comparison tire 1
By forming two pairs of main grooves 21.22 and a plurality of lateral grooves 23, 24, 25 equidistantly spaced in the circumferential direction on the tread surface 20, a plurality of rectangular inner, intermediate,
In this tire, outer blocks 2B and 27.28 are defined, and the inner block 26 and the intermediate and outer blocks 27.28 are offset by 172 pitches in the circumferential direction. In addition, the test tire 1 is a tire in which a step region 2θ is formed in the outer main groove 22 of the comparative tire 1, and each step region 28
connects a rectangular lower portion 30 located at the intersection of the main groove 22 and the lateral groove 24.25, that is, located near the kicking end 35 of the block, and adjacent lower portions 30, Its radially outer end surface 31 is intermediate to the radially outer end surface 32 of the lower part 30, and the cross-sectional contour 33 of the outer block 27, 28
As a result, each stepped region 29 extends continuously in the circumferential direction. In this test tire l, the distance 1lllb between the radially outer end surface 32 of the lower portion 30 and the cross-sectional contour line 33 of the intermediate and outer blocks 27 and 28 is 2 mm, and the distance 1lllb between the radially outer end surface 31 of the high portion 34 and the intermediate , the distance C between the outer blocks 27 and 28 and the cross-sectional contour line 33 is l■■. In this way, each step region 28 is configured by alternately arranging the lower portions 30 and the higher portions 34 in the circumferential direction, and the lower portions 30 are arranged in the middle, near the kicking ends 35 of the outer blocks 27 and 28. The thing is,
The shearing force in the braking direction near the pushed-out end 35 is set to a large value, and the pushed-out end 35 of the intermediate and outer blocks 27 and 28 is
This is to effectively prevent wear in the vicinity. Also.

The test tire 2 is almost the same as the test tire 1, except that the outer end surface in the radial direction and the middle of each step region.

The only difference is that the distance between the outer block and the stepped surface contour line is constant in the circumferential direction (1 inch). Here, the size of each tire mentioned above is 185SR14,
The rim used was 5.5J J-14. After filling each of these tires with an internal pressure of 1.7 kg/lj and installing the tires on the front wheels of an FR passenger car with two passengers on board, the vehicle was driven on a highway with a ratio of 7:3 on ordinary roads. The vehicle was run on a road (all paved) for 40,000 km, and the amount of wear on the road surface was measured at the end of the run. The measurement results are expressed as an index and shown as wear resistance (the higher the index value, the better the wear resistance), and the comparison tire has a 100. It was 108 for test tire 1, 104 for test tire 2, and 111 for test tire 3. As described above, the test tires in which the present invention was implemented had improved wear resistance. Furthermore, here,
Index 100 is 3.2 mm. In addition, at the end of the run, the minimum wear amount near the stepping end and the maximum wear amount near the kicking end of the intermediate and outer blocks were measured, and these measured values were converted into an index to determine uneven wear resistance. . Here, the larger the index value is, the better the uneven wear resistance is, 100 for the comparison tire and 1 for the test tire 1.
23, 118 for test tire 2, 118 for test tire 3
It was 125. As described above, the uneven wear resistance of the test tire according to the present invention is improved, and it is particularly good when a stepped region is provided only near the kicking end of each block. In addition, when each tire mentioned above was run in wet conditions, the web) g index of each tire was determined.
The comparison tire is 100.

Test Tire 3 improved to 112, but Test Tire 1 dropped to 9 days, and Test Tire 2 dropped to 84.

9 to 19 are diagrams showing other embodiments of the present invention. The second embodiment shown in FIG. 9.10.11 is almost the same as the first embodiment, but the main points are that three pairs of main grooves 42, 43, and 44 are formed on the tread surface 41, and that the main groove 42 .43 questions and the blocks 45.48 between the main grooves 43.44 to each other 1
72 pitch shifted and roughly doglegged point, main groove 4
The block 47 between the two, the main groove 44 and the shoulder end 48
The difference is that the blocks 48 between the two are in the same phase. 1st
2.13.14 The third embodiment shown in FIG.
However, the step area 51 is mainly composed of only the lower part, and the radial outer end surface 5 of the step area 51 is
3 is higher at the stepping end 54 and kicking end 55 and lower at the middle thereof, the inner block 5B
They differ in that they are U-shaped so that they fit into each other. 1st
5.16.17 The fourth embodiment shown in FIG.
However, mainly, the radial outer end surface 62 of the stepped region 61 is corrugated in a sawtooth shape, that is, the stepped region e! near the kicking end 65 of the middle, outer block 83, and B4. It differs in that it is made highest and becomes lower as it approaches the depression end 68.

At the initial stage of wear, only the highest portion of the step region 81 is brought into contact with the ground, and as the wear progresses, the contact area of the step region 81 is increased. In this way, it is possible to prevent uneven wear, such as rib punching, which occurs on the block in the middle to late stages of wear. The fifth embodiment shown in FIGS. 18 and 19 is almost the same as the test tire 2, except that the intermediate block 75 is arranged circumferentially shifted by 1/2 pitch with respect to the outer block 78, and there is a step difference. Area 7
7 is bent in a zigzag shape, and each bent portion is placed close to the kicking end 7 of the middle and outer blocks 75 and 78. In this way, a part of the step area 77 is divided into each block 7.
5 and 78, the influence of the step region 77 on the kicking end 78 becomes large;
Wear in the vicinity of the kicking end 78 can be effectively prevented.

In addition, in the above-mentioned embodiment, the case where the stepped region 8 was provided in the main groove 3 was explained, but in this invention,
The stepped region may be provided in a lateral groove, or may be provided in an inclined groove or a bent groove inclined with respect to the tire equatorial plane 4.

As explained above, according to the present invention, heel-and-toe wear of blocks defined on the road surface can be reliably prevented.

[Brief explanation of the drawing]

Fig. 1 is a developed view of a tread showing the first embodiment of the present invention, Fig. 2 is a meridian sectional view thereof, Fig. 3 is a sectional view taken along the first I-I arrow, and Fig. 4 is a tread used in the test. FIG. 5 is a developed view showing the road surface of the comparison tire, FIG. 5 is a meridian cross-sectional view thereof, FIG. 6 is a developed view showing the road surface of the test tire 1 used in the test, FIG. Fig. 6 is a sectional view taken along the line ■-■ in Fig. 6, Fig. 9 is a developed view of a road surface showing the second embodiment of the present invention, Fig. 10 is a meridian sectional view thereof, and Fig. 111 is a cross-sectional view taken along the line m-■ in Fig. 9. 12 is a developed view of a tread showing a third embodiment of the present invention, FIG. 13 is a meridian sectional view thereof, and FIG. 14 is a 12th embodiment.
The sectional view taken along the line l7-IV in the figure, FIG.
FIG. 16 is a meridian sectional view of the road surface showing the embodiment, FIG. 17 is a sectional view along the v--■ arrow in FIG. 15, and FIG. 18 is a road surface showing the fifth embodiment of the present invention Developed view, 1st
Figure 9 is a meridian cross-sectional view. l...Pneumatic tires 2...Road surface? ...Block 8...Several structures 9...Step area 8
a...Radial direction outer end surface 10...Cross-sectional contour line 1
7... Kicking end patent applicant Brideston Co., Ltd. Agent Patent attorney Ta 1) Toshio Figure 1... Pneumatic tire 2... Tread 7... Block 8... Wide groove 9...・Step region 17...Rise end Fig. 9a...Radial direction outer end surface 10...Cross-sectional contour line Fig. Fig. Fig. 5 Fig. Fig. Fig. 5 Figure 1

Claims (1)

[Claims] In a pneumatic tire in which a large number of blocks are defined by forming wide grooves on the tread, at least the wide grooves near the kicking ends of the blocks have their radially outer end surfaces radially inward from the cross-sectional contour line of the blocks. and a stepped area where the outer end surface in the radial direction comes into contact with the road surface when the vehicle reaches the tread surface area, so that the stepped area slides into contact with the road surface during driving and functions as an uneven wear victim part. A pneumatic tire featuring