JP2012071762A - Pneumatic radial tire for aircraft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic radial tire for an aircraft capable of making the durability consistent with weight reduction of the tire.SOLUTION: The pneumatic radial tire 1 for the aircraft has a radial carcass 6, a reinforcing belt 7, and a protection belt 10. The protection belt 10 contains first and second rubber covering layers 11a, 11b in which a plurality of waveform cords having the same cord diameter t are phase-aligned and juxtaposed circumferentially along the tire having the same wavelength and the same amplitude to cover the rubber. The layer of the protection belt 10 is so arranged that the waveform cords of one rubber covering layer are arranged, as viewed in the section of the tire width direction, with a half pitch shifted in the tire width direction with respect to the arrangement position of the wave-form cords of the other rubber covering layer. All of the arrangement interval of the waveform cord in the first rubber covering layer, the arrangement interval of the waveform cord in the second rubber covering layer, and the shortest arrangement interval between the waveform cord in the first rubber covering layer and the waveform cord in the second rubber covering layer are equal.

Description

  The present invention relates to an aircraft pneumatic radial tire used under conditions of high internal pressure and high load, and more particularly to an aircraft pneumatic radial tire capable of achieving both durability and weight reduction of the tire.

  Aircraft pneumatic radial tires are often damaged by treads caused by foreign objects such as stones, nails, bolts, and nuts existing on the road surface during load rolling. Aircraft tires are used under severe conditions such as high internal pressure, high load, and high-speed rotation. Therefore, the above-mentioned damage may lead to failures such as tire burst and tread peeling. Therefore, conventionally, there is a technology for protecting a belt and a carcass by arranging a rubber coating layer formed by rubber coating a plurality of corrugated cords extending along the tire circumferential direction as a protective belt between the belt and the tread. Are known.

  In the pneumatic radial tire for aircraft described in Patent Document 1, a protective belt is constituted by two or more rubber coating layers of inner and outer layers of a plurality of corrugated cords arranged in alignment with each other in phase. In addition, the corrugated cords of the respective rubber coating layers are arranged in phase with each other, and the corrugated cords of one rubber coating layer of the rubber coating layers adjacent to each other are replaced with the corrugated cords of the other rubber coating layer. It is located between. With these configurations, the trauma of the tread is improved without degrading the peel resistance of the tread.

JP 2008-279896 A

  In the tire of Patent Document 1, corrugated cords are arranged at equal intervals in each of the two rubber coating layers as a protective belt. Further, by offsetting the position of the cord in the tire width direction between the inner layer and the outer layer, foreign matter is prevented from slipping between the corrugated cords, and the trauma resistance is improved. However, in this tire, sufficient consideration is not given to the cord interval between the corrugated cord of one rubber coating layer and the corrugated cord of the other rubber coating layer.

  If the cord interval between the corrugated cord of one rubber coating layer and the corrugated cord of the other rubber coating layer is too narrow, separation between cords is likely to occur, which may adversely affect the durability of the tire. Further, if the cord interval between the corrugated cord of one rubber coating layer and the corrugated cord of the other rubber coating layer is too wide, the rubber weight of the protective belt increases, which is not preferable from the viewpoint of weight reduction of the tire. It goes without saying that aircraft tires require high safety, that is, high durability. In addition, since aircraft tires are not used during flight but are mainly used during takeoff and landing, demands for weight reduction are greater than other tires.

  Then, in view of the said subject, this invention aims at providing the pneumatic radial tire for aircraft which can make durability and weight reduction of a tire compatible.

  According to the study of the present inventor, the configuration in which the protective belt is formed of two layers and the position of the corrugated cord of each layer is offset in the tire width direction is preferable from the viewpoint of the damage resistance. Therefore, on the premise of this configuration, further intensive studies were conducted to further increase the durability and weight of the tire, and the position of the corrugated cord of one rubber coating layer and the corrugated cord of the other rubber coating layer. It has been found that the above problems can be solved by optimizing the positional relationship between the waveform codes including the relationship, and the present invention has been completed.

That is, in view of the above problems, the gist of the present invention is as follows.
(1) a radial carcass made of one or more carcass plies extending in a toroidal shape between a pair of bead cores, and a reinforcing belt made of one or more belt layers disposed on the outer periphery of the crown portion of the radial carcass; A pneumatic radial tire for an aircraft, comprising: a protective belt disposed between the reinforcing belt and the tread rubber;
A first and a second, wherein the protective belt is rubber-coated with a plurality of corrugated cords having the same cord diameter t arranged in parallel along the tire circumferential direction with the same wavelength and the same amplitude and the same phase. Including at least a rubber coating layer,
The protective belt has a corrugated position of one rubber coating layer of the first and second rubber coating layers in the tire width direction cross section. Even with a half pitch in the tire width direction with respect to the position of the cord,
Waveform cord arrangement interval in the first rubber coating layer, waveform cord arrangement interval in the second rubber coating layer, and waveform code in the first rubber coating layer and waveform code in the second rubber coating layer The pneumatic radial tire for an aircraft is characterized in that the shortest distance between the two is equal distance L.

  (2) The pneumatic radial tire for an aircraft according to (1), wherein the L is 0.05 mm or more and a waveform code diameter t or less.

  (3) The pneumatic radial tire for an aircraft according to (2), wherein the L is equal to the waveform cord diameter t.

  According to the pneumatic radial tire for aircraft according to the present invention, the distance between all adjacent cords in the two rubber coating layers is made equal, so that both durability and weight reduction of the tire can be achieved. This is a particularly favorable effect for aircraft tires.

1 is a half sectional view in the tire width direction of a typical pneumatic radial tire for aircraft 1 according to the present invention. FIG. 2 is a view of the tire 1 shown in FIG. 1 as seen from above the tread rubber with only a part of the corrugated cords in the first and second rubber coating layers 11a and 11b as the protective belt 10 being seen through. FIG. 2 is a partial cross-sectional view in the tire width direction showing a part of a protective belt 10 (thickness τ) for the tire 1 shown in FIG. 1. 1 is a partial cross-sectional view in the tire width direction showing a part of a protective belt for a comparative tire (Comparative Example 1) in which a protective belt is a single rubber coating layer having a thickness δ. 4 is a partial cross-sectional view in the tire width direction showing a part of a protective belt for a comparative tire (Comparative Example 2) in which two rubber coating layers having the same thickness δ as in FIG. is there. FIG. 5 is a partial cross-sectional view in the tire width direction showing a part of the protective belt for a comparative tire (Comparative Example 3) with a protective belt having the same thickness τ as the tire 1 (FIG. 3) and having a slightly offset waveform code. It is the fragmentary sectional view of the tire width direction which showed a part of protective belt about the comparison tire (comparative example 4) which narrowed the space | interval of the waveform code of two layers rather than the tire 1 (FIG. 3). It is the fragmentary sectional view of the tire width direction which showed a part of protective belt about the comparative tire (comparative example 5) which made the space | interval of the waveform code | cord | chord of two layers wider than the tire 1 (FIG. 3). In an Example, it is a model perspective view of the braid | blade used when evaluating cut durability. In an Example, it is a jig | tool used when evaluating foreign material slipping-through property.

  Hereinafter, the present invention will be described in more detail with reference to the drawings. In principle, the same components are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIG. 1, an aircraft pneumatic radial tire 1 (hereinafter simply referred to as “tire”) according to the present invention includes a radial carcass 6, a reinforcing belt 7, and a protective belt 10 (all of which are shown in half). ) As a basic configuration. Reference numeral 2 denotes a tread portion (only one half is shown), reference numeral 3 is a pair of sidewall portions (only one side is shown), and reference numeral 4 is a pair of bead portions (only one side is shown).

  The radial carcass 6 includes one or more carcass plies extending in a toroidal shape between a pair of bead cores 5 (only one side is shown). The ply constituting the carcass 3 is a cord rubber coating layer, and examples of the cord material include steel and organic fibers. In the case of a radial carcass, the cords are arranged at an angle of 70 ° to 90 ° with respect to the tire circumferential direction. In the present embodiment, a radial carcass composed of five carcass plies is provided, and four of them are turned around each bead core 5 around the bead core 5 from the inner side to the outer side in the tire width direction. An up ply is used, and the remaining one is a down ply that extends inward in the tire radial direction so as to cover the rewind portion of the turn up ply. However, the present invention is not limited to this.

  The reinforcing belt 7 is composed of one or more belt layers disposed on the outer periphery of the crown portion of the radial carcass 6. The belt layer is a rubber coating layer formed by coating a cord with rubber, and typically includes a cross belt layer in which two belt plies whose inclination angles with respect to the tire equatorial plane are opposite to each other are bonded together. Examples of the cord include a steel cord and an organic fiber cord.

  For example, a cushion rubber 8, a protection belt 10, and a tread rubber 9 are sequentially disposed on the outer side of the reinforcing belt 7 in the tire radial direction.

  The protective belt 10 is disposed between the reinforcing belt 7 and the tread rubber 9. The protective belt 10 includes at least a first rubber coating layer 11a formed by rubber coating a plurality of corrugated cords 12a and a second rubber coating layer 11b formed by rubber coating a plurality of corrugated cords 12b. The protective belt 10 has a role of protecting the reinforcing belt 7 and the carcass 6 when the tread portion 2 is damaged by a foreign matter. Thereby, as a result of improving the trauma resistance, the durability of the tire is enhanced, and the possibility that the reinforcing belt 7 is damaged and cannot be rehabilitated (retreaded) can be reduced. As shown in FIG. 2, the waveform cords 12a and 12b are rubber-coated in the same wavelength d and the same amplitude A and aligned in the tire circumferential direction with the phases aligned with each other, as shown in FIG. Have the same cord diameter t.

  Further, as shown in FIG. 3, the protective belt layer 10 has a corrugated cord of one rubber covering layer among the corrugated cords 12a and 12b in the first and second rubber covering layers as viewed in the cross section in the tire width direction. The arrangement position of 12a or 12b is arranged with a half-pitch shift in the tire width direction with respect to the arrangement position of the corrugated cord 12b or 12a of the other rubber coating layer.

  As shown in FIG. 4 as a comparative example, when the protective belt 20 has a single layer, in order to prevent foreign matter from slipping through the waveform cords 20a and to improve the trauma, the waveform code interval L1 is inevitably set. It was necessary to narrow. However, since this causes separation between cords, the durability of the tire is lowered from this viewpoint. (In FIG. 4, the cord diameter t is equal to the cord interval L1.)

  In the present invention, the protective belt is multilayered and the corrugated cords of each layer are offset from each other in the tire width direction, thereby increasing the number of corrugated cords while keeping the interval between adjacent corrugated cords at a predetermined value or more. The gap between the cords seen from the side can be reduced. Therefore, it is possible to improve the traumatic property while suppressing the separation between cords.

  Further, as shown in FIG. 3, the characteristic configuration of the present invention is that the code intervals of all adjacent waveform codes are made equal for a plurality of waveform codes embedded in the two rubber coating layers 11a and 11b. is there. That is, the disposition interval of the corrugated cord 12a in the first rubber coating layer 11a, the disposition interval of the corrugated cord 12b in the second rubber coating layer 11b, and the corrugated cord and the second rubber in the first rubber coating layer 11a. The shortest distance between the corrugated cords in the covering layer 11b is made equal.

Let L1 be the interval between adjacent corrugated cords in the first and second rubber coating layers. In addition, a predetermined corrugated cord (for example, corrugated cord 12a ₁ ) of _one rubber covering layer (for example, the first rubber covering layer 11a) of the first and second rubber covering layers and the other rubber adjacent thereto. The distance between the coating layer (second rubber coating layer 11b) and the two waveform cords (12b ₂ , 12b ₃ ) is L2 and L3. If grasped one layer and the second rubber coating layer 11b, the interval between the waveform code 12b _1, a first waveform code _12a 2 of two rubberized layers 11a, 12a ₃ adjacent thereto is L2, L3 It becomes. These L2 and L3 correspond to “the shortest arrangement interval between the waveform code in the first rubber coating layer 11a and the waveform code in the second rubber coating layer 11b”. The present invention is characterized in that these L1, L2, and L3 all have the same value L, and an equilateral triangle is formed by connecting the centers of adjacent waveform codes. By adopting this configuration, it is possible to further improve the trauma property while further suppressing the separation between cords. The reason will be described below with reference to a tire as a comparative example.

As a comparative example, FIG. 5 shows that two rubber coating layers having the same thickness δ as the protective belt of FIG. 5 are provided, and the corrugated cords 22b ₂ , 22b ₃ , 22b ₁ of the second rubber coating layer 21b are This is an example in which the rubber covering layer 21a is disposed at a position offset in the tire width direction by t / 2 (1/4 pitch) from the waveform cords 22a ₁ , 22a ₂ , 22a ₃ . In this case, L1, L2, and L3 are different from each other. In this comparative example, the cord diameter t = L1, but since the offset amount is t / 2, when the waveform cord is observed from the tread rubber information, a gap is always generated between the cords. For this reason, it is not possible to prevent foreign matter from passing between the waveform cords, and the damage resistance is not sufficient. In this comparative example, since the thickness 2 × δ of the protective belt is larger than the thickness τ of the protective belt in the tire 1 of the present invention, the protective layer cannot be reduced in weight.

As a comparative example, FIG. 6 shows that two rubber coating layers having the same thickness τ as the tire 1 of the present invention are provided, and the corrugated cords 32b ₂ , 32b ₃ , 32b of the second rubber coating layer 31b are provided. ₁ is arranged at a position offset in the tire width direction by t / 2 (1/4 pitch) from the waveform cords 32a ₁ , 32a ₂ , 32a _{3 of} the first rubber coating layer 31a. Also in this case, L1, L2, and L3 are different from each other. Even in this comparative example, the cord diameter t = L1, but the offset amount is t / 2. Therefore, when the waveform cord is observed from above the tread rubber, a gap is always generated between the cords. For this reason, it is not possible to prevent foreign matter from passing between the waveform cords, and the damage resistance is not sufficient.

As a comparative example, FIG. 7 shows an example in which an isosceles right triangle is formed when the interval between the corrugated cords between the two layers is narrower than that of the tire 1 of the present invention and the centers of adjacent corrugated cords are connected. The corrugated cords 42b ₂ , 42b ₃ , 42b ₁ of the second rubber coating layer 41b are made to have a tire width that is equal to the cord diameter t (half pitch) than the corrugated cords 42a ₁ , 42a ₂ , 42a _{3 of} the first rubber coating layer 41a. It is the same as the tire 1 of the present invention in that it is disposed at a position offset in the direction. In this example, L1> L2 = L3. In this comparative example, since the cord diameter t = L1 and the offset amount is t equal to the cord diameter, when the waveform cord is observed from above the tread rubber, no gap is generated between the cords. However, according to the study of the present inventor, since the intervals L2 and L3 between adjacent waveform codes between layers are too narrow, inter-code separation is likely to occur. Note that the thickness α of the protective belt is smaller than τ.

As a comparative example, FIG. 8 shows an example in which an isosceles triangle having an apex angle of 30 ° is formed when the interval between the corrugated cords is wider than that of the tire 1 of the present invention and the centers of adjacent corrugated cords are connected. is there. The corrugated cords 52b ₂ , 52b ₃ , 52b ₁ of the second rubber coating layer 51b are made to have a tire width that is equal to the cord diameter t (half pitch) than the corrugated cords 52a ₁ , 52a ₂ , 52a _{3 of} the first rubber coating layer 51a. It is the same as the tire 1 of the present invention in that it is disposed at a position offset in the direction. In this example, L1 <L2 = L3. In this comparative example, since the cord diameter t = L1 and the offset amount is t equal to the cord diameter, when the waveform cord is observed from above the tread rubber, no gap is generated between the cords. However, according to the study of the present inventor, since the distances L2 and L3 between the adjacent waveform cords between the layers are too thick, the protective layer cannot be reduced in weight. The protective belt thickness β is larger than τ.

  On the other hand, when L1 = L2 = L3 as in the present invention, the balance between the suppression of the separation between cords and the weight reduction of the protective layer is the best, and both the durability and the weight reduction of the tire can be sufficiently achieved. is there.

  In the tire 1, the cord diameter t is preferably 0.5 mm or more and 2.0 mm or less.

  The amplitude A of the waveform code is preferably 2 mm or more and 20 mm or less.

  Further, the wavelength d of the waveform code is preferably 10 mm or more and 50 mm or less.

  The interval L between adjacent waveform codes is preferably 0.05 mm or more and the waveform code diameter t or less. If it is less than 0.05 mm, the cord interval is too close, and there is a possibility that separation between cords may occur. Further, if L <t, when the waveform cord is observed from above the tread rubber, there is no gap between the cords reliably, so that foreign matter can be more sufficiently suppressed from passing between the waveform cords. This is because the damage resistance can be further improved.

  More preferably, the adjacent waveform code interval L is equal to the waveform code diameter t. In this case, when the waveform cord is observed from above the tread rubber, the cord interval can be maximized in a range in which no gap is generated between the cords as shown in FIG. For this reason, it is possible to make separation between cords more difficult to occur while maintaining the damage resistance.

  The protective belt 10 has been described as the inner and outer two-layer rubber coatings 11a and 11b, but the protective belt 10 may of course be configured with three or more rubber coating layers. For example, when the third rubber coating layer 11c is further arranged on the first rubber coating layer 11a and the second rubber coating layer 11b, the waveform cords in the third rubber coating layer 11c are arranged at the second position. It is preferable to align with the first rubber coating layer 11a by shifting the pitch of the corrugated cord of the rubber coating layer 11b by a half pitch in the tire width direction. Thereby, not only from the direction perpendicular to the tread surface, but also to the insertion of a foreign object having a predetermined angle with respect to the direction perpendicular to the tread surface, the slipping between the cords can be effectively suppressed.

  As the material of the corrugated cord, aromatic polyamide fiber, aliphatic polyamide fiber and other organic fiber cords are advantageous in terms of weight reduction of the tire. Especially, it is suitable from the point of intensity | strength and code | cord | chord thickness to make the cord which twisted the aromatic polyamide fiber to the fineness of 3300 dtex / 3.

  The dimensional relationship of the present invention described so far describes the design philosophy of the present invention, and the present invention allows manufacturing errors caused as a result of manufacturing tires based on this design philosophy. It goes without saying that it is a thing.

  Next, in order to further clarify the effect of the present invention, an aircraft pneumatic radial tire (tyre size: APR1400 × 530R23 40PR) according to the following examples and comparative examples is mounted on an applicable rim and used. The comparative evaluation will be described. Items common to each pneumatic tire are as follows.

For the example tires and comparative tires 1 to 5, the following four performance tests were performed. The results are shown in Table 1.
<Cut durability>
As shown in FIG. 9, a blade having a width of 500 mm, a thickness of 1.5 mm (bottom thickness of 5.0 mm), and a height of 30 mm is gradually pressed against the tire, and the force until the cord of the protective belt is cut is measured. Comparative example 1 was taken as 100 and displayed as an index. The larger the index, the better the cut durability.

<Foreign material slip-through>
As shown in FIG. 10, a jig was prepared in which eleven conical protrusions having a diameter of 2.0 mm and a height of 30 mm were arranged at intervals of 50 mm, and the number of protrusions that passed through the tires through the tire was measured. . The comparative example 1 was set to 100, and the index was displayed so that the smaller the number of slipping through, the larger the index. That is, the larger the index, the better the trauma resistance.

<Separation between codes>
A drum test was performed, and the running time until the separation between cords was measured was measured. The larger the index, the less the separation between cords, and the better the durability of the tire.

<Protective layer weight>
The weight of the protective belt was measured, and the index was displayed with Comparative Example 1 as 100. The larger the index, the heavier the protection belt.

  Example tire 1 is an evaluation item related to tire durability compared to comparative tires 1 to 3, with regard to cut durability, foreign object slipping property, interlayer separation property, and protective layer weight which is an evaluation item related to tire weight reduction. Excellent characteristics in a well-balanced manner.

  According to the pneumatic radial tire for aircraft of the present invention, it is possible to achieve both durability and weight reduction of the tire by making all the cord intervals in the two rubber coating layers equal.

DESCRIPTION OF SYMBOLS 1 Airplane radial tire 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 7 Reinforcement belt 8 Cushion rubber 9 Tread rubber 10 Protection belt 11a 1st rubber coating layer 11b 2nd rubber coating layer 12a 1st Waveform code 12b Second waveform code

Claims (3)

A radial carcass composed of one or more carcass plies extending in a toroidal shape between a pair of bead cores, a reinforcing belt composed of one or more belt layers disposed on the outer periphery of the crown portion of the radial carcass, and the reinforcing belt A pneumatic radial tire for an aircraft having a protective belt disposed between the tire and the tread rubber,
A first and a second, wherein the protective belt is rubber-coated with a plurality of corrugated cords having the same cord diameter t arranged in parallel along the tire circumferential direction with the same wavelength and the same amplitude and the same phase. Including at least a rubber coating layer,
The protective belt has a corrugated position of one rubber coating layer of the first and second rubber coating layers in the tire width direction cross section. It is arranged with a half pitch shift in the tire width direction with respect to the arrangement position of the cord,
Waveform cord arrangement interval in the first rubber coating layer, waveform cord arrangement interval in the second rubber coating layer, and waveform code in the first rubber coating layer and waveform code in the second rubber coating layer The pneumatic radial tire for an aircraft is characterized in that the shortest distance between the two is equal distance L.   The pneumatic radial tire for an aircraft according to claim 1, wherein the L is 0.05 mm or more and a corrugated cord diameter t or less. The pneumatic radial tire for an aircraft according to claim 2, wherein the L is equal to the waveform cord diameter t.

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