JPH01106704A - Pneumatic tire for heavy load - Google Patents

Abstract

PURPOSE:To improve the performance on an icy and snowy road by forming block rows, in the central crown region by means of broken-line shaped circumferential main grooves and inclined auxiliary grooves, and in the shoulder regions by means of the outermost broken-line shaped main grooves and width- directional auxiliary grooves respectively, and further by forming transverse directional cuts in respective blocks. CONSTITUTION:In the central region C of a tread crown, block rows 2 and 3 are formed by means of circumferential broken-line shaped main grooves 5-7 and inclined width-directional auxiliary grooves 16 and 17, and in the shoulder regions S, block rows 1 and 4 are formed by means of broken-line shaped main grooves 5, 7 and tire width-directional auxiliary grooves 19. And in these respective blocks, cuts 22 transverse to the circumferential direction of the tire are formed respectively. Thereby water films are scraped away to enhance the close contact of the tread rubber surface with the ice surface, and to increase the efficiency in frictional resistance. Thus, the performance on an icy and snowy road can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heavy-duty pneumatic tire that simultaneously satisfies braking and driving performance on icy and snowy roads, running stability and wear resistance on dry roads, etc.

[Conventional technology]

Conventionally, heavy-duty pneumatic tires such as truck tires and bus tires have been constructed with a plurality of polygonal or zigzag main grooves 1 extending in the circumferential direction of a relatively large tire, as shown in the plan view of FIG. Tread crown center area C
A lug groove 2 is provided in the shoulder area S, and the blocks arranged in a row are further divided by a sub-groove 3 having a smaller width.
There are tires that have formed tread patterns. This tread pattern has excellent braking and driving performance of the tire on snowy roads, but on the other hand, it has the disadvantage that it tends to cause uneven wear called heel-and-toe wear and shoulder drop wear on dry roads. In addition to the uneven wear resistance, the volume of the grooves at Yukigamisha is increased to ensure braking and driving performance, so the groove ratio on the tread surface is as large as 45-50χ, so the wear resistance itself is improved. It was inferior. Since the blocks are divided into small, independent blocks, the rigidity of the blocks is low, and the stability of the vehicle during cornering on dry roads is significantly inferior compared to a rib pattern.

Moreover, FIG. 4 is a plan view of a tread pattern called an all-season pattern of a conventional tire. Compared to the conventional tires mentioned above, it is possible to improve wear resistance by forming individual blocks larger and setting the groove ratio to 35 to 40χ, but this also reduces braking and driving performance on snowy roads. I couldn't avoid it.

Moreover, although heel-and-toe wear and shoulder-drop wear are improved compared to tires with the trend pattern shown in Figure 3, they are not sufficient, and when using a steering shaft,
It is difficult to avoid such reductions in heel-and-toe wear and shoulder-drop wear, and even if measures such as partially reducing the groove depth of the lug grooves are taken, satisfactory results cannot be obtained and, on the contrary, braking Driving performance deteriorates.

・Furthermore, conventional heavy-duty pneumatic tires satisfy braking and driving performance on soft snowy roads, but do not provide sufficient performance on hard or icy roads such as compacted snow, resulting in chain failure. Some required assistance and had no choice but to change to spiked tires.

[Purpose of the invention]

The object of the present invention is to improve the shortcomings of the conventional heavy-duty pneumatic tires, and to provide sufficient braking and driving performance not only on icy and snowy roads in winter, especially on soft snowy roads, but also on hard, compacted snowy roads, and even on frozen roads. To provide a pneumatic tire for heavy loads, which has a tread pattern that exhibits excellent wear resistance, suppresses occurrence of uneven wear on dry road surfaces, etc., and has excellent wear resistance performance.

[Structure of the invention]

The object of the present invention is to (I) provide at least three protrusion rows in the central region of the tread crown, which are arranged in parallel along the circumferential direction of the tire and intermittently have at least groove components parallel to the circumferential direction of the tire; Consisting of a polygonal block partitioned by a book's folded main groove and a plurality of auxiliary grooves with predetermined intervals between the folded lined main grooves that are adjacent to each other and whose inclination directions are alternately different, II) The block row in the tread shoulder region protrudes between the broken line main groove located closest to the shoulder side, the shoulder side edge, and the groove component parallel to the tire circumferential direction toward the shoulder side between the two. This can be achieved by a tire comprising blocks partitioned by auxiliary grooves connected at the groove component positions, and (III) the blocks of (I) and (II) have cuts that cross the tire circumferential direction. can.

Preferably, the ratio (a/L*) of the tire lateral direction length (L,) of the block constituting the trend crown central region to the tire circumferential direction length (a) of the block center portion is 0.4.
5 to 0.70, and the ratio (b, le,
is preferably within the range of 0.90 to 1.25.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is an example of a plan view for explaining a method for forming grooves in a tread pattern of a heavy-duty pneumatic tire (hereinafter simply referred to as a tire) according to the present invention. As shown in the figure, in the tread crown central region C, there are line components parallel to the tire circumferential direction (20.2
Three fold lines 5.6.7 (corresponding to the lead) with intermittent 0' are provided. Among these three fold lines, the points (8 and 12 and 9 and 15) where the fold points of the fold lines adjacent to each other are closest are connected by lines 16 and 17 (corresponding to the auxiliary grooves), and these auxiliary grooves Formation line 16.1
7 and the broken line 5.6.7 are the block row 2 of the tread crown central region C.
．． form 3.

On the other hand, in both tread shoulder areas S, the fold line 5.7 located closest to the shoulder area, the shoulder side edge 18,
A component 20.20 parallel to the tire circumferential direction between the two
'The blocks defined by the line 19 connecting at the position of the component 20 protruding toward the inner shoulder constitute the block row 1.4 of the tread shoulder area S.

FIG. 2 is a plan view showing an example of the tread pattern of the tire of the present invention produced by the groove device method shown in FIG.

However, between the adjacent fold lines of the tread crown center area C (8
and 12 and 9 and 15) are connected by stepped lines 16 and 17.

These trend crown center area C and shoulder area S
A plurality of notches 22 are provided in each of the blocks.

First, in the present invention, it is necessary that the blocks constituting the trend surface have the cut 22 formed in a direction transverse to the circumferential direction of the tire.

In other words, if we consider the case where the braking/driving force on an icy and snowy road surface wears out the tire tread surface, the many edges of each block divided by the notches 22 formed in the block will form a thin water film on the ice surface. This increases the adhesion between the water surface and the tread rubber surface, increasing the efficiency of the frictional resistance of the tread surface against the water surface.

Further, in the case of a compacted snow road surface, the edges of the blocks dig into the compacted snow road surface, increasing the resistance of the tread surface. Furthermore, in addition to the edge effect of the above block,
Due to the edge effect of the notches formed on the block surface,
With driving and braking forces acting on the tire tread surface, the contact between each block and the road surface is improved. That is, FIG. 5 and FIG. 6 are a sectional view and a cross-sectional view, respectively, showing the deformed state when a driving force (arrow) is applied to a block B without a notch 22 and a block B with a plurality of notches 22. FIG. 3 is a plan view showing the grounding shape of each block B; (a) in Figures 5 and 6, respectively.
As shown in , when a driving force (arrow) is applied to block B, block B is deformed by the shearing force, but the part of the block on the opposite side to which the force is applied lifts off the road surface.
State of non-contact with the road surface (respectively (b) in Figures 5 and 6)
) becomes the white part). As is clear from the figure, the fifth
The block that does not have the notch 22 in Figure (a) is shown in Figure 5 (
As shown in FIG. 6(b), only a part of the surface contacts the road surface, whereas the blocks provided with the notches 22 in FIGS. 6(a)-(7) are shown in FIG. 6(b). Almost the entire surface is in contact with the road surface. That is, by forming a cut in the block, the edge effect of the block and the frictional force against the road surface (snow-compacted road and icy road) are increased. The effect of improving the ground contact of such cuts in the block is not only on the above-mentioned compacted snow and icy roads, but also on dry roads.If the block does not have cuts, the frictional energy of sliding on the non-ground contact area is large. , which can cause heel-and-toe wear, whereas blocks with notches do not.

Here, in order to more effectively impart the above-mentioned edge effect, the incision formed in the block of the tire of the present invention should be in a direction transverse to the circumferential direction of the tire, preferably in the range of 90' to 70' with respect to the circumferential direction of the tire. It is best to set it at an angle within
The shape is preferably linear, but it can also be curved or stepped. Further, the depth of the cut is preferably at least 60% or more of the leading depth in order to be effective on icy and snowy roads up to the snow abrasion limit display (50x of the leading depth). Further, the pitch of the cuts (interval between the arrangement of the cuts) is 6 to 20 mm, preferably 8 to 1
A value within the range of 5 mn+ is preferable.

In other words, if the pitch is too narrow relative to the direction and depth of the above-mentioned grooves, the block rigidity will decrease in the case of tires with large loads such as heavy-duty tires, and the blocks will collapse upon contact with the ground, resulting in poor ground contact. When this decreases and becomes severe, a problem occurs in which blocks are missing. Furthermore, if the width is too wide, the grounding properties of the block will deteriorate, which is not preferable.

The thinner the thickness of the cut, the better, but it is preferably 0.8 mm or less. In particular, it is preferable to form this incision not in the tire mold but by cutting the tire tread after vulcanization. Items with notches formed with a mold are 0.
．． It is preferable to set it within the range of 4 to 0.8 mm.

The tire of the present invention has at least three main grooves intermittently having groove components parallel to the tire circumferential direction, and the main grooves adjacent to each other are arranged at predetermined intervals and alternately. It has a block pattern consisting of blocks partitioned by multiple auxiliary grooves with different inclination directions, that is, mesh-like grooves, and this block pattern is effective for the tread surface when driving on snowy roads (soft roads). This makes it possible to trap snow. Also, the second
As shown in the figure, in the central region C of the tread crown, blocks with larger dimensions in the lateral direction than in the circumferential direction of the tire are arranged in parallel, so that a large number of thin cuts can be effectively formed in these blocks. , can be arranged, and there is no pitch deviation between the auxiliary grooves arranged alternately and the block rows.

By providing auxiliary grooves 16 and 17 alternately arranged in opposite directions with respect to the tire circumferential direction connecting the adjacent broken line main gaps, the block rows in the tread crown central region C, for example the block rows in FIG. 2 and 3 are arranged in parallel in a zigzag pattern, and there is no pitch shift between alternating auxiliary groove block rows unlike in conventional tires shown in Figures 3 and 4, resulting in excellent braking and driving performance. .

Furthermore, since no acute angle is formed in the contour of the block, heel-and-toe wear can be suppressed.

In the conventional tires shown in Figures 3 and 4, the pitch is shifted to prevent heel-and-toe wear. It is difficult to achieve both reduction in wear and braking/driving performance. In contrast, the tire of the present invention is advantageous in that it can prevent heel-and-toe wear and achieve both braking and driving performance due to the synergistic effect with the notches of the blocks described above.

Since the block rows are arranged in parallel, it is possible to effectively provide a plurality of thin cuts in the blocks, and since there are no acute angles in the outline of the blocks, it is possible to suppress the occurrence of heel-and-toe wear. can.

Here, the depth of the auxiliary groove provided on the tread surface of the present invention is preferably within a range of 0.5 to 0.8 times the depth of the main groove.

That is, the block row (2
, 3) parallel to the tire circumferential direction (9-16, 1l
-18), by increasing the block rigidity, arranging a thin cut near the center of the block, and lowering the rigidity of the central part of the block to reduce the rigidity between it and the peripheral part of the block in the tire circumferential direction. It is possible to suppress wear and improve the tire's ground contact.

Furthermore, it is desirable that the blocks constituting the block row in the central region of the tread crown have the same shape and the same length of groove components (20° and 20° in Fig. 1) parallel to the tire circumferential direction on both left and right sides. However, as a noise reduction measure, the pinch variation range is excluded). If the sizes of blocks in the circumferential direction of the tire are different, a difference in rigidity occurs, which may be disadvantageous against heel-and-toe wear.

In addition, the block rows in the shoulder region S have larger dimensions than the blocks in the tread crown center region C, and the ratio of the tire lateral length (L2) to the tire circumferential length (b)
Az) is preferably within the range of 0.90 to 1.25. In other words, a block that is large in size, stable in shape, and satisfies the above ratio (bAz) reduces the connection rate in the shoulder area and increases tread density, improving stability during cornering on dry road surfaces. let me,
It is also advantageous in suppressing wear and tear caused by collapse when the stay 7 ring shaft is attached.

Further, the block in the central region of the tread crown has a ratio (a/L+) of the tire lateral length (L, ) to the tire circumferential length (a) within the range of 0.45 to 0.70. This is preferable, and thereby provides good snow-biting properties on soft snow and good ground contact properties on hard compacted snow and water surfaces.

In addition, in order to increase the actual ground contact area of the tread of the tire of the present invention, effectively exert frictional resistance on the ice surface, and maintain good wear resistance, the groove ratio of the entire tread should be 30 to 40X. It is preferable to keep it within this range.

〔Example〕

EXAMPLES Hereinafter, the present invention and its effects will be explained in more detail with reference to Examples.

Experimental example 1 The following three types of tires were created.

Main school office: Tire size is 10.0OR2014P
A tire having the following dimensions and the tread pattern of FIG.

Tread development width = 214n+m, groove ratio = 36χ, main groove depth = 19.5mm, auxiliary groove depth = 15mm, number of cuts in each block making up the block row in the central area of the tread crown = 2, in the shoulder area Depth of cut for each block that makes up the block row - 14.5m
m (approximately 374 of the leading groove depth), pitch = 11-13
1. Number of cuts = multiple, a/L1 = 0.54, b
/Lz= 1.06, and the auxiliary grooves that connect the leading corner points are folded back to make the center block rigidity uniform in the circumferential direction (as shown in Figure 7, it does not impair snow-biting performance. (As shown in the figure, the straight line connecting each bending point is a straight line that passes through even if there is a fold.)

Conventional tire A: Tire size is 10.0OR2014P
A tire having the following dimensions and the tread pattern shown in FIG.

Tread development width = 220mm, groove ratio = 47χ, main groove depth: 19.5mm.

Conventional tire B: Tire size is 10.0OR2014P
A tire having the following dimensions and the tread pattern shown in FIG.

Tread development width = 200mm, groove ratio = 37χ, main groove depth: 17. Omm.

Wear test ■l: Test tires were mounted on all wheels of a test truck, and the vehicle was driven for 50,000 m.

Heel-and-toe wear was investigated from the amount of step difference between the blocks in the circumferential direction of the tire after driving on an actual vehicle, and shoulder drop wear was investigated from the amount of step difference between the block rows in the center area of the tread crown and the block rows in the shoulder area. The smaller these measured values (relative index values), the better the wear performance.

In addition, the estimated lifespan was evaluated from the amount of wear on the grooves.

The larger this value (relative index value) is, the longer the estimated lifespan is.

Braking/driving performance evaluation: Braking was started at a vehicle speed of 30km on a snow-covered road and a water road, and the braking distance until the vehicle came to a stop was measured. The smaller the measured value (relative index value), the better the braking performance.

In addition, we measured the passing time over a certain section on a sloped road surface with soft snow to evaluate pitching performance. measured value(
The smaller the relative index value), the better this pitching performance is.

The evaluation results are shown in Table 1 as relative index values, with the measured value for the conventional tire set as 100.

(The following is a blank space) Table 1 [Effects of the Invention] According to the present invention, as a heavy-duty tire, it is possible to exhibit high braking and driving performance not only on snow-covered roads but also on compacted snow and icy roads in winter. It has excellent running performance and wear resistance on dry road surfaces, and its lifespan can be greatly extended.

[Brief explanation of the drawing]

FIG. 1 is a plan view for explaining the method of arranging the tread pattern of the tire of the present invention, FIG. 2 is a plan view showing one embodiment of the tread pattern of the tire of the present invention, and FIGS. 3 and 4 are respectively , top views of conventional tire tread patterns, FIGS. 5(a), (b), and 6(a).
, (b) is a cross-sectional view showing the deformation state when a driving force is applied to a block without a cut and a block with a plurality of cuts, and a plan view showing the corresponding ground contact shape of those blocks, respectively; FIG. 7 is a partial plan view showing the puflock of the tire of the present invention. 1.2.3.4...Block row, 5.6.7...Circumferential main groove, 8-15...Break point, 16.17...Auxiliary groove, 18...Shoulder side Edge, 19...Auxiliary groove (lag groove), 20.20"...Groove component parallel to the tire circumferential direction, C...Tread crown center area, S...Tread shoulder area. Agent Patent attorney Shin Ogawa -

Claims (1)

[Scope of Claims] (I) The block row in the central region of the tread crown consists of at least three broken lines arranged in parallel along the circumferential direction of the tire and having intermittently at least groove components parallel to the circumferential direction of the tire. (II) A tread consisting of a polygonal block partitioned by a shaped main groove and a plurality of auxiliary grooves with predetermined intervals between the adjacent broken line-shaped main grooves and whose inclination directions are alternately different; (II) a tread; The block row in the shoulder area connects the broken line main groove located closest to the shoulder, the shoulder side edge, and a groove component protruding toward the shoulder of the groove component parallel to the tire circumferential direction between the two. (III) A heavy-duty pneumatic tire comprising blocks partitioned by auxiliary grooves connected at positions, and characterized in that the blocks (I) and (II) have cuts that cross the tire circumferential direction.