Pneumatic vehicle tire having rubber rim flap, wheel comprising pneumatic vehicle tire, and use of rubber rim flap

Abstract

The invention relates to a pneumatic vehicle tire having two sidewalls (5) terminating in a bead region (8), in which the bead region (8) is formed with a bead core (3), a carcass insert (4) extending around the bead core, and a rubber rim flap (7) forming the outer surface of the bead region (8), the rubber rim band (7) is arranged at least partially between the rim (1) and the bead core (3) in a position for using the vehicle pneumatic tire on the rim (1), the rubber rim band (7) being formed as a single piece from a rubber compound, and the rubber compound being arranged at least partially between the rim (1) and the bead core (3) in a position for using the vehicle pneumatic tire on the rim (1). The rubber compound has a loss factor (tan [delta]) of between 0.02 and 0.2 at 20 DEG C according to DIN 53512 and a Shore hardness in the range of 65 Sh-A to 80 Sh-A measured by means of a durometer at 20 DEG C according to DIN ISO 7619-1. The invention also relates to a wheel having such a pneumatic vehicle tire, and to the use of a rubber rim flap.

Description

Technical Field

[0001] This invention relates to a pneumatic tire for vehicles, particularly a radially designed pneumatic tire, having two sidewalls terminating in a bead region, wherein the bead region forms a bead core, a carcass insert extending around the bead core, and a rubber rim pad forming the outer surface of the bead region, and in a position for use on a rim, the rubber rim pad is at least partially disposed between the rim and the bead core. The invention also relates to a wheel having a rim and a pneumatic tire mounted on the rim, and to the use of the rubber rim pad. Background Technology

[0002] For example, a type of pneumatic tire of the kind mentioned at the beginning is known from DE 10 2020 206 734 A1. In this known embodiment, a rubber rim pad (forming the outer surface of the bead region and at least partially disposed between the rim and the bead core at the location for using the pneumatic tire on the rim) is produced in two parts from different rubber compounds, ensuring a friction-reducing and robust fit of the pneumatic tire on the rim. By selecting a rubber compound with high stiffness (typically higher than the stiffness of the pneumatic tire sidewall) to produce the rubber rim pad, the rubber rim pad imparts the desired high lateral stiffness to the pneumatic tire. Furthermore, the rubber rim pad has a considerable influence on the rolling resistance of the pneumatic tire, which must be optimized in the desired conflict. The high lateral stiffness of the rubber rim pad is desirable while minimizing rolling resistance. Summary of the Invention

[0003] Therefore, the object of the present invention is to provide a vehicle pneumatic tire of the type mentioned at the beginning, which has reduced rolling resistance without sacrificing lateral stiffness compared to known configurations.

[0004] To achieve the above objectives, a vehicle pneumatic tire having the features of claim 1 is proposed according to the present invention.

[0005] Advantageous configurations and developments of the invention can be obtained from the dependent claims.

[0006] Within the scope of this invention, it is established that the aforementioned objective, specifically the resolution of the conflict between high lateral stiffness and low rolling resistance in a vehicle's pneumatic tire, can be achieved by the following method: the rubber rim pad is integrally formed from a rubber compound having a loss factor (tanδ) between 0.02 and 0.2 at 20°C according to DIN 53512 and a Shore hardness in the range of 65 Sh-A to 80 Sh-A as measured by means of a durometer at 20°C according to DIN ISO 7619-1.

[0007] As proposed in this invention, the rubber rim pad strip formed from this rubber compound imparts to the pneumatic tire of the vehicle constructed in this manner lateral stiffness comparable to that of the prior art, while optimizing rolling resistance.

[0008] According to the proposal of the invention, the loss factor (tan δ) of the rubber compound of the rubber rim pad is equal to or less than the loss factor (tan δ) of the sidewall measured at 20°C according to DIN 53512 in their respective cases. Such a vehicle pneumatic tire has the same lateral stiffness as in the prior art, but with a loss factor (tan δ) comparable to that of the sidewall.

[0009] Within the scope of this invention, the term "rubber compound" includes vulcanized and unvulcanized rubber compounds, particularly vulcanized rubber compounds.

[0010] According to DIN 53512, the loss factor (tan δ) can be determined from the resilience R of the rubber compound used to form the rubber rim pad.

[0011] For small values ​​of the loss factor, the relationship between resilience R and the loss factor (tan δ) is as follows:

[0012] R = 1 - π × (tan δ)

[0013] The resilience R itself can be obtained according to DIN 53512 at a given temperature, for example, 20°C, by allowing a pendulum to strike the surface of a test specimen of a rubber compound perpendicularly at a specified velocity with a kinetic energy of 0.5 J and calculating the resilience based on the ratio of the pendulum’s rebound height to the fall height (usually expressed as a percentage).

[0014] According to the invention, the loss factor (tan δ) of the rubber compound of the rubber rim pad belt, measured according to DIN 53512 at a temperature of 20°C, is between 0.02 and 0.2, preferably between 0.03 and 0.08, and more preferably between 0.04 and 0.06.

[0015] According to the present invention, the Shore hardness of the rubber compound of the rubber rim pad is, in each case, measured by a hardness tester at 20°C according to DIN ISO 7619-1, in the range of 65 Sh-A to 80 Sh-A, preferably between 68 Sh-A and 77 Sh-A, more preferably between 70 Sh-A and 75 Sh-A, and even more preferably between 71 Sh-A and 73 Sh-A. The hardness grade Sh-A refers to Shore hardness A, as established for hardness testing of soft elastomers.

[0016] According to another proposal of the invention, the rubber rim pad of the vehicle pneumatic tire according to the invention is formed of a rubber compound based on 15 to 35 phr of natural rubber and about 85 to 65 phr of butadiene rubber, thereby further optimizing the rolling resistance. The ratio of natural rubber to butadiene rubber in the rubber compound constitutes 100 phr in each case.

[0017] According to another proposal of the invention, the rubber compound of the rubber rim pad may further include filler, preferably carbon black, wherein the filler is particularly preferably present in an amount of 45 to 65 phr, thereby setting the lateral stiffness.

[0018] According to another proposal of the invention, the rubber compound of the rubber rim pad belt may include zinc oxide and stearic acid, wherein preferably the total amount of zinc oxide and stearic acid is selected in the range of 4 to 8 phr. By changing the ratio of zinc oxide and stearic acid, rolling resistance can be optimized without sacrificing lateral stiffness.

[0019] According to another proposal of the invention, the rubber compound of the rubber rim pad belt may also contain sulfur in an amount of 1 to 5 phr in order to further improve lateral stiffness.

[0020] Furthermore, the rubber compound of the rubber rim pad of the pneumatic tire of the vehicle according to the invention may preferably contain additional vulcanizing agents, such as suitable vulcanization accelerators, in an amount of 1 to 10 phr, particularly preferably 3 to 5 phr, especially 4 phr. Additionally, anti-aging agents and processing aids may be added to the rubber compound of the rubber rim pad of the pneumatic tire of the vehicle according to the invention.

[0021] The present invention also relates to a wheel having a rim and a vehicle pneumatic tire mounted on the rim, as described above.

[0022] In addition, the present invention also relates to the use of the rubber rim pad belt as described above for the production of the aforementioned vehicle pneumatic tires or wheels. Attached Figure Description

[0023] Further configurations and details of the invention will be explained below with reference to the accompanying drawings, which illustrate exemplary embodiments.

[0024] A single figure shows a cross-sectional view through the bead region of a wheel according to the invention in an exemplary embodiment. Detailed Implementation

[0025] You can see the bead area 8 of the vehicle pneumatic tire, which is mounted on the rim 1 and is specifically designed for radial tires. The bead area 8 is radially adjacent to the sidewall 5.

[0026] The bead region 8 includes a bead core 3 and a carcass insert 4 that extends around the bead core 3 and, in the exemplary embodiment shown, terminates in a carcass wrap 4a that extends in the direction of the sidewall 5.

[0027] The bead core 3 is radially outwardly adjacent to the core profile 6; in addition, the inner layer 2 of the vehicle's pneumatic tire, which terminates below the bead core 3, is shown by reference numeral 2 in the attached drawing.

[0028] The outer surface of the bead region 8 is formed by a rubber rim pad 7, which wraps the bead core 3, the carcass insert 4 wrapped around the bead core, and the end region of the inner layer 2 extending around the bead core 3 in a generally U-shaped cross section.

[0029] In the state shown where it is mounted on the rim 1, the rubber rim pad 7 abuts against the rim flange 1a of the rim 1 in region 9a and against the rim portion 1b of the rim 1 in region 9b, and extends beyond the rim flange 1a with a thickness of 10 until the rubber rim pad merges into the sidewall 5.

[0030] The main feature of the rubber rim pad 7 is that, in order to achieve high lateral stiffness of the vehicle's pneumatic tire on the rim 1 and at the same time achieve optimized reduction of rolling resistance, the rubber rim pad is integrally formed of a rubber compound having a loss factor (tan δ) between 0.02 and 0.2 at 20°C according to DIN 53512 and a Shore hardness in the range of 65 Sh-A to 80 Sh-A as measured by means of a durometer at 20°C according to DIN ISO 7619-1.

[0031] For example, the rubber compound used has a loss factor (tan δ) of 0.04 to 0.06 at 20°C and a Shore hardness of 71 Sh-A to 73 Sh-A according to DIN 53512.

[0032] For this purpose, the rubber rim pad 7 is produced from a rubber compound having the following formulation:

[0033] 25 phr natural rubber

[0034] 75 phr butadiene rubber

[0035] 55 phr carbon black

[0036] 10 phr anti-aging agents and processing aids

[0037] 6 phr zinc oxide and stearic acid

[0038] 4 phr vulcanization accelerator

[0039] 3.5 phr sulfur

[0040] The composition of the formulation can vary throughout the formulation, with tolerances of ±10%, preferably ±5%, and particularly ±2%, in each case, to ensure high lateral stiffness while simultaneously ensuring optimal reduction in rolling resistance.

[0041] The production of the rubber compound used to form the rubber rim pad 7 is typically carried out in a conventional manner by initially producing a base mixture containing all components except for the vulcanization system (sulfur and vulcanization accelerator) in one or more mixing stages, and then producing a finished mixture by adding the vulcanization system, from which the rubber rim pad 7 is formed.

[0042] For material testing purposes, test specimens can also be produced in a laboratory tangential mixer by vulcanizing at 160°C under pressure for 20 minutes.

[0043] By inserting the rubber rim pad 7 formed of the rubber compound into a conventional standard vehicle pneumatic tire with a radial design, it was found that comparable lateral stiffness and improved rolling resistance were achieved compared to conventional vehicle pneumatic tires.

[0044] List of reference numerals

[0045] 1 rim

[0046] 1a Rim flange

[0047] 1b Rim Section

[0048] 2 Inner Layer

[0049] 3-Tire Beads

[0050] 4-piece body insert

[0051] 4a Fetal body reverse wrapping

[0052] 5. Sidewall

[0053] 6-core profile

[0054] 7 Rubber rim pads

[0055] 8. Bead area

[0056] A portion of the outer surface of the 9a bead area

[0057] Another part of the outer surface of the 9b bead area

[0058] 10. Thickness of the rubber rim pad in the transition area to the tire sidewall.

Claims

1. A vehicle pneumatic tire having two sidewalls (5) terminating in a bead region (8), wherein, These bead regions (8) are formed with bead cores (3), carcass inserts (4) extending around these bead cores, and a rubber rim pad (7) forming the outer surface of the bead regions (8), and in the location for using the vehicle's pneumatic tire on a rim (1), the rubber rim pad is at least partially disposed between the rim (1) and these bead cores (3), characterized in that the rubber rim pad (7) is integrally formed of a rubber compound having a loss factor (tan δ) between 0.02 and 0.2 at 20°C according to DIN 53512 and a Shore hardness in the range of 65 Sh-A to 80 Sh-A measured by means of a durometer at 20°C according to DIN ISO 7619-1.

2. The vehicle pneumatic tire as described in claim 1, characterized in that, The wear factor (tan δ) of the rubber compound of the rubber rim pad (7) is equal to or less than the wear factor (tan δ) of the sidewall (5) measured at 20°C according to DIN 53512 in their respective cases.

3. The vehicle pneumatic tire as described in claim 1 or 2, characterized in that, The rubber rim pad (7) is formed from a rubber compound based on 15 to 35 phr natural rubber and 85 to 65 phr butadiene rubber.

4. The vehicle pneumatic tire as described in any one of claims 1 to 3, characterized in that, The rubber compound of the rubber rim pad (7) contains filler, preferably carbon black, in an amount of 45 to 65 phr.

5. The vehicle pneumatic tire as described in any one of claims 1 to 4, characterized in that, The rubber compound of the rubber rim pad (7) contains zinc oxide and stearic acid in an amount of 4 to 8 phr.

6. The vehicle pneumatic tire as described in any one of claims 1 to 5, characterized in that, The rubber compound of the rubber rim pad (7) contains sulfur in an amount of 1 to 5 phr.

7. A wheel having a rim (1) and a vehicle pneumatic tire as described in any one of the preceding claims mounted on the rim (1).

8. The use of the rubber rim pad (7) as described in any one of the preceding claims for the production of a vehicle pneumatic tire as described in any one of claims 1 to 6 or a wheel as described in claim 7.

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