JPS647043Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to pneumatic construction vehicle tires, and more particularly to pneumatic construction vehicle tires having a generally lug tread pattern. The basic performance requirements for this type of tire are excellent traction, wear resistance, heat resistance, and resistance to lug chipping. Recently, as vehicles have become larger and faster, the conditions under which tires are used have also shifted to higher speeds.As a result, tires have become larger and each part of the tire has become thicker, resulting in excessive internal heat accumulation. Due to the deterioration of each member due to heat, so-called separation damage is becoming noticeable. Therefore, as measures to improve heat resistance, (a) changing the composition of the tread rubber, (b) changing the carcass structure to reduce the amount of heat generated, and (c) working from the groove bottom to the carcass surface in the tread pattern. Attempts have been made to reduce the undertread thickness and deepen the tread groove by that amount in order to increase the amount of heat dissipation, but none of these measures has been sufficient and each has its own drawbacks. had. In other words, countermeasure (a) tends to be contradictory in that the lower the heat generation of the rubber compound, the more the wear resistance and cut resistance (lag chipping resistance) are impaired. The countermeasure was not expected to be very effective in terms of improving heat resistance, and the countermeasure (c) also had drawbacks, such as the wear resistance and lug chipping resistance being rather impaired. The present invention was developed in response to this situation, and the present invention focuses on the fact that as a tire wears, the tread thickness decreases, and as a result, the internal accumulation of heat decreases. At the beginning of a long run, the heat dissipation effect is sufficient, and at the middle to end of the run, when the tread wall thickness decreases and the internal accumulation of heat becomes smaller, the wear resistance increases, and even at the beginning of the run, there is sufficient lag resistance. This has led to the provision of a tire that is resistant to chipping. In order to achieve this purpose, the lug sub-grooves are mainly used to enhance the heat dissipation effect during the early stages of running when there is a large amount of internal heat accumulation, and the lug grooves are used to improve wear resistance during the mid to late stages of running when the internal heat accumulation is low. A tread pattern is formed in which the lug minor grooves disappear in order to increase the tread pattern, and in particular, the standard type with a minimum of 16.00 (tire width, inches) - 25 (rim diameter, inches) or 2.05 A pneumatic tire for construction vehicles of a wide base type with a minimum diameter of -25 has a tread pattern that is an array of lugs that are generally perpendicular to the circumferential direction and open at least at one end. The main lug grooves and the sub-lug grooves, which are substantially parallel to the main lug grooves from the edges of both sides of the tread toward the center line of the tire, alternate between the main lug grooves and the main lug grooves. The width and depth percentages of the minor grooves relative to the main lug grooves are 20 to 100% and 30 to 70%, respectively, on the tire circumferential surface, and the width of the minor lug grooves on the tire surface is small. Both are characterized by being 15mm. The pneumatic tire of the present invention having such characteristics is
The tread pattern is shown in FIG. 1, and a portion of the tread is shown in an enlarged cross-section in FIG. As is clear from the pattern, the crown portion 1 includes lug main grooves 2 that cross each other with a slight intersecting angle in the axial direction of the tire.
Between the adjacent lug main grooves 2, 2 are provided lug sub grooves 3 extending substantially parallel to the lug main grooves from the edges on both sides of the tread, that is, the boundary between the tread part and the shoulder part, toward the center line of the tire. are provided, and the lug main grooves 2 and the lug sub grooves 3 are arranged alternately. In the case shown in FIG. 1, both the lug main groove 2 and the lug sub-groove 3 extend straight, and while the lug main groove 2 crosses the entire width of the tread, the lug sub-groove 3 By terminating short of the center of the tread, it extends on each side of the center. On the other hand, in the case shown in FIG. 3, both the lug main groove 2 and the lug sub-groove 3 extend on both sides of the tread center, and extend toward the tread center line from the edges of both sides of the tread. A large number of lug grooves, consisting of a main groove and a pair of sub-grooves facing each other, are arranged alternately in the circumferential direction of the tire, and furthermore, the lug main groove 2 and the lug sub-groove 3 are both bent. There is. The lug main groove 2 and the lug sub-groove 3 having such shapes have specific dimensions in terms of the following conditions. First, the length of the lug sub-groove 3 in the tire axial direction is equal to the half width L of the tread. In contrast, it is preferable that the length is at least 0.3L. Also, referring to the sectional view of FIG. 2, the width of the lug main groove 2 is W, the depth is H, and the width of the lug minor groove 3 is When w is the depth and h is the depth, w=(0.2~1.0)W, h=(0.3~0.7)H
It is preferable to determine the dimensions of the two so that the following dimensional relationship is established, and as a result, a tire with excellent heat resistance or heat dissipation effect, abrasion resistance, and lug chipping resistance can be obtained. However, if w is too small, no heat dissipation effect can be expected, so it is desirable to set it to 15 mm or more. The above-mentioned dimensional relationship was specified because if the width w of the lug minor groove 3 is too small, the heat dissipation effect of the tire cannot be expected, whereas if it is too large, the wear resistance and lug chipping resistance are poor. , and further lug minor groove 3
It has been theoretically proven that if the depth h is too shallow, heat dissipation will be poor, while if it is too deep, wear resistance and lug chipping resistance will be poor. As a result, it was confirmed that the above-mentioned dimensional relationship is appropriate as a condition. This will be explained below using examples. Tire size E-3, 18.00-33 32PR Carcass Nylon 6, 1890d/2 cord used Tires according to the present invention A and B Conventional tires C and D Inventive tires A and B and conventional tires C and D without lug grooves The results of a comparative test are shown in Table 1 below. However, in the columns of invention tires A and B in Table 1,
The numbers in parentheses represent the dimensions of the lug minor groove 3, respectively. Further, positions on the tread that are closer to the tread center line by 1/8 and 1/4 of the tread width 2×L from the tread edge are defined as 1/8 points and 1/4 points, respectively.

[Table] *Running was canceled due to heat separation.
Here, tire TKPH value (Ton−Km−Per−
The measurement of (Hour) was carried out as follows. Tire pressure 5.6Kg/ ^cm2 , load 11.5 tons, room temperature 38℃, drum diameter 1.7m, 18, 20, 22Km/h
The tire was run on the drum at three levels until the tire temperature reached a constant saturation temperature, and the TKPH of each of the four types of new tires A, B, C, and D was measured.
Graph the maximum temperature inside the tire as shown in Figure 5 and read the TKPH at 112℃. This TKPH is based on the fact that heat separation, which is one of the tire failures, depends on the tire internal temperature.
TKPH values up to 112℃ are unique to that tire.
It is called the TKPH value and is the evaluation value of possible work from the perspective of heat generation. TKPH = Tire load (ton)
Calculated by x speed (Km/h). On the other hand, the wear life is the result of using a 32-ton rear dump truck at an air pressure of 5.6 kg/cm ² . According to Table 1, the tires A and B of the present invention having the lug minor grooves 3 have a high TKPH value and have excellent load capacity. Furthermore, it can be seen that the present invention is considerably superior in terms of wear life despite the provision of the lug sub-groove 3. Next, in Fig. 4, the relationship between tread wear amount and tire temperature is shown by comparing the tire of the present invention (solid line) and the conventional tire (dashed line, no lug minor grooves, otherwise the same). It has been clearly shown that the lug minor grooves have an excellent heat dissipation effect on the heat generated by a new tire in the early stages of running. As detailed above, the present invention contributes to improving heat resistance and abrasion resistance, thereby extending the life of tires, and is especially effective when installed on construction vehicles used under harsh conditions. It is a pneumatic tire that plays.

[Brief explanation of drawings]

1 and 3 are tread pattern diagrams of the tread portion of each example of the tire of the present invention, FIG. 2 is an enlarged sectional view taken along the line A-A' in FIG. 1, and FIGS. 4 and 5. are a chart comparing the relationship between tire temperature and TKPH and a chart comparing the relationship between tire temperature and tread wear amount. 2...Lug main groove, 3...Lag minor groove.

Claims (1)

[Scope of utility model registration request] For standard type pneumatic tires for construction vehicles with a minimum of 16.00 (tire width, inches) - 25 (rim diameter, inches) or wide base type pneumatic tires with a minimum of 20.5 - 25, approximately in the circumferential direction as a whole. The tread has a tread pattern that is an array of lugs formed by orthogonal grooves that are open at least at one end thereof, and between the main lug grooves and the adjacent main lug grooves, from the edges of the tread on both sides. Sub-lug grooves substantially parallel to the main lug grooves are alternately provided toward the center line of the tire, and the width and depth percentages of the sub-lug grooves relative to the main lug grooves are such that 20~ each
100% and 30 to 70%, and the width of the lug minor groove on the tire surface is at least 15 mm.