A vehicle wheel

Abstract: A vehicle wheel comprises a wheel rim (11) and a pneumatic tire (10) fitted to the rim, particularly a tubeless tire wherein the wheel rim includes seats (12) for the tire beads (20). The rim seats (12) include an elevating ridge (14) which is spaced from the rim lips and the tire beads (20) have a generally corresponding configuration. With the tire fitted to the rim, the tread cores (19) of the tire are located between the rim lips (12) and the elevating ridge (14). According to the invention, the rim (11) is a 15° rim with a 15° seat surface (15) between rim flip (12) and elevating ridge (14). The side (16) of the elevating ridge remote from the rim lips extend at an angle of 15-40° essentially in a straight line from the crown of the elevating ridge in a direction inwards towards the rim centre. The invention also relates to a wheel rim having rim seats and elevating ridge of the same configuration.

Description: The present invention relates to a vehicle wheel, i.e. a pneumatic tire and wheel rim assembly, according to the preamble of Claim 1. It is known to configure a rim seating with a "hump", i.e. an elevating ridge which is spaced from the rim shoulder or lip so that, when the tire is fitted to the rim, the bead cores of the tire will be located between the elevating ridge and the rim lip. The purpose of these elevating ridges, or humps, is to enhance the firmness in which the tire is held on the rim, so that the tire is able to withstand natural forces to which it is subjected when the vehicle is turned sharply or driven under off-road conditions. This construction is often used in low profile tires, particularly extremely low profiles such as broad off-road tires. One example of a vehicle wheel of this kind is illustrated and described in U.S. Publication US-A 4,034,792. In this known construction, the firmness with which the tire is held against the rim has been improved by providing the sidewalls of the tire with an outwardly projecting ridge, which engages around the rim lip so as to provide an additional holding force. This known vehicle wheel has a so-called 5° rim, i.e. a rim in which the rim seats form an angle of 5±1° to the rotational axis of the rim. The procedure of fitting a tubeless tire to a wheel rim involves a number of steps. Firstly, one tire bead is forced over one rim lip or shoulder and then pressed mechanically in towards the opposite rim lip. The other tire bead is then also forced over said one rim lip, whereafter the tire is inflated so that both tire beads will be pressed outwardly towards respective rim lips, such that the bead cores are located between the rim lips and the elevating ridge. One problem encountered when fitting the tire is that the tire has difficulty in accommodating the air delivered to the tire, in other words, the air leaks from the tire between tire bead and rim seat, due to unsatisfactory contact between tire bead and rim seat. This problem is mostly caused when the tire has been stored incorrectly, so that prior to being fitted the distance between the beads of the tire is considerably shorter than the corresponding distance when the tire has been fitted and inflated. Another problem that can occur when fitting the tire to the rim is that the tire beads may snap past the elevating ridges. In the case of this known vehicle wheel, one elevating ridge has sloping sides and the other ridge has a very broad crown which is inclined at a smaller angle than the bottom of the circumferential groove, i.e. the actual rim seat. It can therefore be difficult to push the tire bead over this broad ridge, when fitting the tire. U.S. Publication US-A 3,915,215 illustrates another example of a vehicle wheel comprising a 5° rim provided with an elevating ridge or hump. In the case of this known vehicle wheel, the tire beads are constructed so that the beadheels and the tread cores are located between the rim lip and elevating ridge, whereas the tiretoe lies inwardly of the elevating ridge, i.e. on the side of the ridge that is distal from the rim lip. This arrangement also provides additional locking of the tire beads so as to better prevent the tire bead from sliding away from the rim lip when the tire is subjected to powerful lateral forces, i.e. when negotiating curves and when driving under off-road conditions. A tire of this known kind is also fitted to the rim in the manner aforedescribed. As before mentioned, a 5° rim is used in vehicle wheels taught by the aforesaid U.S. publications. The problems encountered when fitting tires to rims in which the rim seats are inclined at such a small angle are not equally pronounced in the case of so-called 15° rims, i.e. rims in which the rim seats form an angle of 15±1° to the rotational axis of the rim. It is also known to use an elevating ridge on rim seats that are given a slope of 15° in order to improve the firmness by which the tire is held to the rim. For instance, Swedish published specification SE-B-436 721 teaches a vehicle wheel comprising a tire of standard profile, wherein the rim seats are inclined at 15°. In this case, the ridges are very short and are provided with a generally radial abutment surface which faces towards the rim lips. However, it is far more difficult to fit a tire onto a rim of this kind than when using rims in which both rim seats are angled at 5°, and all of the problems that exist with 5° rims still remain, and in certain cases are even amplified. An object of the present invention is to provide a vehicle wheel with which the tire can be fitted more easily despite the use of a 15° rim. Another object is to provide a vehicle wheel in which the rim seats are so designed that the tire will seal against the rim seats at an earlier stage than with known vehicle wheels thereby facilitating fitting of the tire. These and other objects are achieved when the vehicle wheel is constructed in the manner defined in Claim 1. Other advantageous embodiments of the invention are defined in the dependent Claims. An exemplifying embodiment of an inventive vehicle wheel will now be described in more detail with reference to the accompanying drawings. Figure 1 is a radial sectioned view of an inventive vehicle wheel. Figure 2 illustrates the wheel rim in larger scale. Figures 3-6 illustrate different stages of a tire fitting operation while displacing the tire bead out towards the rim seat and the rim lip. Figure 1 illustrates a pneumatic, tubeless low-profile tire 10 fitted onto a wheel rim 11. The rim includes rim lips 12 and rim seats 13 which lie inwardly of the lips 12. The rim seats include an elevating ridge 14, a so-called hump, which divides the seats into two seat-parts 15, 16. As will best be seen from Figure 2, the seat-parts 15 and 16 have a generally rectilinear configuration and are inclined at different respective angles α and β to a line which extends parallel with the rotational axis of the rim and the vehicle wheel. The radial distance between the rotational axis of the rim and the vehicle wheel and the crown of the elevating ridge is smaller than the rim radius, i.e. the radial distance between the aforesaid rotational axis and the chain line 18 in Figure 2. It has been found that a suitable vertical ridge extension (i.e. the radial distance between the ridge crown and a straight line extension of the bottom of the rim seat-part 15) is 4-8 mm, said crown lying at a distance from the rim radius line 18 which is roughly half as large. The most suitable value for each individual vehicle tire can be established by one of normal skill in this art with the aid of simple experiments. The radial distance to the crown of the elevating ridge, however, must be shorter than the radial distance between the inner periphery of the tread-cores 19 of the tire in the tire beads 20 of the vehicle tire. The tire can be fitted much more easily when the vehicle wheel and wheel rim respectively are constructed in the aforesaid manner. This is evident from Figures 3-6, which illustrate movement of the tire bead 20 towards the rim lip 12 during a tire fitting operation. Figure 3 illustrates the stage of a tire-fitting operation immediately prior to the tire bead coming into contact with the rim seat-part 16. Because the seat-part 16 is generally rectilinear and slopes at a greater angle than the actual rim seat, i.e. the seat-part 15, the undersurface 21 of the tire bead will come early into sealing contact with the seat-part 16 and the rim 14. The steep slope of the seat-part 16 also results in a relatively high abutment pressure, which in turn results in a high sealing effect and therewith in improved air-retaining ability during the tire-fitting operation. When the internal pressure increases as the tire is inflated, the tire bead will slide over the crown of the elevating ridge 14 (Figure 5) while maintaining the aforesaid high sealing efficiency. Finally, the tire bead snaps out to its ultimate fitting position, as illustrated in Figure 6, wherewith the tireheel 22 abuts the rim lip 12 and the tiretoe 23 embraces the elevating ridge 14 and is also pressed sealingly against the rim seat-part 16. In total, the result is an extremely efficient seal and enhanced security against air leakage when the vehicle concerned negotiates a sharp curve or is driven under off-road conditions, even when the tire has an extremely low profile. In the illustrated embodiment, the rim seat-part 15 is inclined at an angle α of 15° and the seat-part 16 is inclined at an angle β of 34°. According to accepted standards within the field, the angle a may vary with ±1°. The angle β may vary within the range of 15° to 40° within the concept of the present invention. The lower limit is preferably 20° or 25°, whereas the upper limit is preferably 35°. Although the invention has been described and illustrated with reference to an extremely low profile tire, since such tires are often the most difficult to fit and with which the advantages afforded by the invention are therefore most noticeable, it will be understood that the invention'can be applied equally as well to low profile tires of a more conventional kind and also with tires of normal profile.

Claims: A vehicle wheel comprising a wheel rim (11) and a pneumatic tire (10) fitted thereto, particularly a tubeless tire, wherein the rim includes rim lips (12) having rim seats (13) located inwardly of the rim lips and receiving tire beads (20), and wherein the rim seats include an elevating ridge (14) which is spaced from the rim lips, and wherein the tire beads have generally a corresponding configuration and, when the tire is fitted, the bead cores (19) of said tire are located between the rim lips (12) and the elevating ridge (14), and wherein the rim (11) is a 15° rim with a 15° seat surface (15) between rim lips (12) and elevating ridge (14), characterized in that the elevating ridge (14) divides the seat surface into two seat-parts (15, 16); in that the seat-part (15) between the elevating ridge (14) and the rim lips (12) slopes at an angle (α) of 15°, and the seat-part (16) on the side (16) of the elevating ridge remote from the rim lips is generally rectilinear and slopes at an angle (β) which is greater than angle (α), but at the most 40°; in that the elevating ridge extends on the side (16) remote from the rim lips generally rectilinearly from the crown of the elevating ridge inwardly towards the rim centre; and in that the tire toe (23) of the tire beads (20) embrace the elevating ridge (14) and are pressed sealingly against the side (16) of the elevating ridge remote from the rim lips (12). A wheel according to Claim 1, characterized in that the side (16) of the elevating ridge (14) remote from the rim lips (12) slopes at an angle of 20-35°, preferably at an angle of 25-35°- A wheel according to Claim 2, characterized in that the side (16) of the elevating ridge (14) remote from the rim lips (12) slopes at an angle of about 35°. A wheel according to any one of the preceding Claims, characterized in that the rim (11) is a drop-centre rim. A wheel according to any one of the preceding Claims, characterized in that the elevating ridge (14) has a vertical extension of 4-8 mm. A wheel according to any one of the preceding Claims, characterized in that the pneumatic tire (10) is a low profile tire.

Inventors: VICTOR CARL-GUSTAV BOERJE CHRI, VICTOR, CARL-GUSTAV BOERJE CHRISTER, Victor, Carl-Gustav Börje Christer
Applicants: TRELLEBORG TYRE AB
Application year: 1992
Main classification: B60B21
IPC codes: B60B21, B60C15