WO1997035734A1

WO1997035734A1 - Pneumatic tire having vented bead ring flange

Info

Publication number: WO1997035734A1
Application number: PCT/US1997/004777
Authority: WO
Inventors: Richard N. Crano
Original assignee: Continental General Tire, Inc.
Priority date: 1996-03-27
Filing date: 1997-03-26
Publication date: 1997-10-02
Also published as: AU2544297A

Abstract

A tire is provided, having a tread portion, and inner and outer sidewall portions extending radially inward therefrom toward, respectively, inner and outer bead ring portions. The inner and outer bead ring portions provide mating surfaces, respectively, for mating with corresponding inner and outer surfaces of a wheel rim to which the tire is mounded. The inner and outer bead ring mating surfaces are provided with a generally continuous circumferentiall groove extending generally about the peripheries thereof, and at least one radial groove connecting with the circumferential groove and extending radially outward thereform. The radial groove(s) may be either straight, extending directly radially outward from the circumferential groove, or curved, generally curving away from the the circumferential groove in a direction opposite to an intended direction of rotation of the tire. The circumferential groove serves to collect air which is trapped between the tire bead flange and the wheel rim flange during mounting of the tire to the rim, and the radial grooves serve to vent the collected air to the outside environment, improving the fit of the tire onto the rim.

Description

PNEUMATIC TIRE HAVING VENTED BEAD RING FLANGE Field of the Invention

The present invention relates generally to pneumatic tires and more particularly to a pneumatic tire having a vented bead ring flange for venting air which might otherwise become trapped between the bead ring flange and a wheel rim flange when the tire is mounted on the rim.

Background of the Invention

Pneumatic tires are typically mounted onto rims at least twice during their lifetimes. Initially, tires are mounted onto a chuck or rim on a test machine for testing the force variation uniformity of the tire as the tire is rotated by the machine. Additionally, at least one more time during the serviceable lifetime of the tire, the tire is mounted upon a wheel rim prior to being placed in service.

Typically, pneumatic tires are mounted onto rims at the location of inner and outer bead ring portions which extend about the circular inner and outer bead openings in the tire. The inner and outer bead ring portions connect inner and outer sidewall portions of the tire, respectively, to the tire tread. The tread is typically provided with reinforcement belts, especially in the case of a radial tire.

Figure 1 shows a partial sectional detail of a tire Tl mounted upon a rim R. Although only the outer bead portion BP of the tire is shown up to the beginning of lower sidewall SW, and only the outer segment of the rim is shown, it is to be understood that the inner bead ring portion of the tire is similarly mounted to the inner segment of the rim (inner bead ring, inner sidewall, and tread of tire Tl not shown in Figure 1) . As used herein, "radial" shall mean in either direction to/from an axis about which the tire rotates from/to the tire tread, and "lateral" shall mean in a direction to/from either sidewall of the tire from/to the other sidewall. "Radially inward" shall mean toward the axis of rotation and "radially outward" shall mean toward the tread; "laterally inward" shall mean toward the inner sidewall and "laterally outward" shall mean toward the outer sidewall.

As shown in Figure 1, both the rim R and the tire Tl are provided with radial surfaces RS and lateral surfaces LS, which in an ideal mounting mate flush against each other. The lateral and radial surfaces of the rim are connected by a shoulder S and the lateral and radial surfaces of the tire are connected by a bead heel BH. Primary sealing of the pneumatic tire Tl is provided by the interface of the corresponding radial surfaces RS of the tire and rim. The bead ring BR provides a compressive force which forces the radial surface of the tire against the radial surface of the rim. Secondary sealing of the pneumatic tire is provided by the interface of the corresponding lateral surfaces LS of the tire and rim.

The rim R is also provided with a safety hump SH which extends slightly radially outward from the radial surface RS of the rim. The safety hump inhibits a bead toe BT of the tire from moving laterally inward so as to prevent the tire from being dislodged from its mounting on the rim.

As explained above, the portions of the tire bead portion BP which mount directly against the rim R are designed to fit flush against each other. Specifically, the lateral and radial surfaces of the tire are designed to closely seat against those of the rim, and the bead heel BH is designed to closely seat against the shoulder of the rim. In a typical mounting, however, several forces prevent the tire from ideally seating snugly up against the rim.

Typically, the tire is inflated in order to seat the bead portion of the tire up against the rim. With further reference to Figure 1, friction develops between the tire bead portion BP and the rim as the tire is inflated and the bead portion begins to move laterally outward. This friction increases significantly as the bead portion encounters and begins to overcome the rim safety hump SH. After moving laterally outward past the safety hump SH, the compressive force of the bead ring BR persists in causing a frictional force to develop at the interface of the corresponding radial surfaces RS of the tire and rim. This developed frictional force is directed laterally inward and opposes the outward lateral movement of the bead portion with respect to the rim at the radial surface RS interface. The magnitude of this frictional force is compounded by the dimensional differences of the tire and the rim. Typically, the outer diameter of the rim is slightly greater than the inner diameter of the tire bead opening. The frictional force is also magnified by a slight ramp inclination (about 5°) of the radial surface of the rim in a direction laterally outward.

In part because of the frictional force at the radial surface interface of the tire and the rim, and in part because the sidewall SW portion of the tire is less rigid than the bead portion, the tire inflation process often causes the lower sidewall portion to meet the rim at location X before the bead heel BH can properly seat up against the rim shoulder S. The sidewall shape may also influence the manner and time in which the lower sidewall portion meets the rim. As shown in Figure 1, the bead heel BH has moved laterally outward only to location Y at the point at which the lower sidewall portion meets the rim at location X, there by trapping air at the location of a void V formed between the bead heel BH and the rim shoulder S . As the tire continues to inflate, a compressive force is developed by the air being compressed in the void V.

This compressive force, like the frictional force developed between the radial surface RS interface of the tire and the rim, is directed laterally inward and thus serves to further oppose the outward lateral movement of the bead portion with respect to the rim at the radial surface RS interface. In this manner, even when the tire becomes fully inflated, the laterally outward force developed by the compressed air within the body of the tire may be insufficient to overcome (i) the frictional force developed at the interface of the corresponding radial surfaces RS of the tire and rim, and (ii) the compressive force developed by the compressed air in the void V. If the laterally outward force developed by the compressed air within the body of the tire is insufficient to overcome these forces directed laterally inward, the bead portion of the tire may never properly seat on the rim. Improper seating of the tire on the rim is the source of several known problems. First, in testing the tire for force variation uniformity, as explained above, the tire is mounted upon a test chuck or rim and rotated. If the measurements taken at the test machine indicate that the force variation of the tire are outside of prescribed specifications, the tire may be either rejected or abrasively ground at one or more locations to bring the force variation within specification. If a tire is mismounted on the test machine due to improper seating of the tire on the test rim, an acceptable tire may be inappropriately rejected, or may be improperly ground to improper specifications.

Moreover, once placed in service, if a tire is mismounted on a wheel due to improper seating of the bead portion on either the inner or outer segment the rim, the corresponding shoulder of the tread may be pulled radially inward. In such circumstances, the performance of the tire may be adversely affected. Moreover, if the bead portion of the tire is improperly seated on the rim, rotational slippage of the tire with respect to the rim may occur. If such slippage occurs, any balancing of the wheel and tire assembly which may have been performed will be disrupted. It is therefore an object of the present invention to provide a mechanism for improving the seating of a pneumatic tire upon a rim to which it is mounted. Sum ary of the Invention A tire is provided, having a tread portion, and inner and outer sidewall portions extending radially inward therefrom toward, respectively, inner and outer bead ring portions. The inner and outer bead ring portions provide mating surfaces, respectively, for mating with corresponding inner and outer surfaces (flanges) of a wheel rim to which the tire is mounted. The inner and outer bead ring mating surfaces are provided with a generally continuous circumferential groove extending generally about the peripheries thereof, and at least one groove connecting with the circumferential groove and extending radially outward therefrom. Alternatively, a circumferential ridge disposed adjacent to and radially inward from the circumferential groove may be provided, to insure the seal between the tire bead portion and the rim flange. Preferably, a plurality of radially extending grooves are provided, positioned at equally spaced locations about the peripheries of the bead portions of the tire. The radially extending grooves may be generally straight and extend directly radially outward from the circumferential groove, or they may generally curve away from the circumferential groove.

Additionally, the inner and outer bead ring portions of the tire may be provided with a chamfered edge. The chamfered edge of the bead ring portion lies preferably at an angle of about 45° as measured with respect to the rim flange.

Brief Description of the Drawing

Figure 1 is a partial sectional view of a known tire/rim assembly;

Figure 2A is a partial sectional view of a tire/rim assembly constructed according to the principles of the present invention; Figure 2B is a partial sectional view of an alternative embodiment of a tire constructed according to the principles of the present invention;

Figure 3 is a plan view of the tire shown in the tire/rim assembly shown in Figure 2A; Figure 4 is a plan view of another alternative embodiment of the tire shown in the tire/rim assembly shown in Figure 2A; and

Figure 5 is a partial sectional view of another alternative embodiment of a tire/rim assembly constructed according to the present invention. Detailed Description of the Preferred Embodiment

The present invention provides a system and method for efficient mounting of a tire onto a rim to insure proper seating of a bead portion of the tire onto a mounting flange of the rim. The invention comprises a tire having one or more grooves formed therein at locations on the bead ring flange which mate with the rim mounting flange. The grooves provide means for venting air which might otherwise become trapped between the tire bead ring flange and the wheel rim flange to prevent precise seating of the tire onto the rim. A tire/rim assembly constructed according to the principles of the present invention is partially shown in Figure 2A. Portions of the tire T2A in Figure 2A having similar construction to that of corresponding elements of the tire T in Figure 1 are identified by the same alphabetic reference characters . The rim R of Figure 2A is identical to that shown in Figure 1.

The tire T2A of Figure 2A differs from the tire Tl of Figure 1 in several respects. First, a continuous circumferential groove CG is formed in the circumference of the tire outer bead flange (i.e., in the lateral surface LS of the tire bead portion) . The circumferential groove CG is formed about halfway up the lateral surface LS of the tire bead portion. The circumferential groove CG may also be formed on the inner bead flange.

In addition, one or more radial grooves RG are also formed in the tire outer bead flange (also see Figures 3 and 4) . The radial grooves RG begin at the circumferential groove CG (and therefore connect with the circumferential groove CG) , and extend radially outward at least as far as the innermost point on the sidewall portion which mates with the rim flange RF. The radial grooves RG may also be formed on the inner bead flange. The circumferential groove CG serves to collect air which is trapped between the tire bead flange and the wheel rim flange during mounting of the tire T2A to the rim R, and the radial grooves RG serve to vent the collected air to the outside environment, improving the fit of the tire onto the rim. In an alternative embodiment, the circumferential grooves CG are discontinuous, forming a plurality of arc-shaped grooves about the peripheries of their respective bead ring mating surfaces, wherein each of the radial grooves connects with an arc-shaped groove.

Figure 2B is a partial sectional view of an alternative embodiment of a tire constructed according to the principles of the present invention, wherein the tire bead ring flange is provided with a circumferential ridge CR, extending about the circumference of the bead ring flange adjacent the circumferential groove CG. The circumferential ridge CR is located radially inward from the adjacent circumferential groove CG, and insures a better seal between the tire bead rings and rim flanges . The circumferential ridge CR may have dimensions similar to that of the circumferential groove (see below) , except that the ridge is complementary (i.e., extending laterally outward rather than laterally inward) . When the tire T2B is mounted to the rim, the cirumferential ridge CR compresses sufficiently to conform to the surface of the rim flange, (i . e . compression sets or permanently deforms over time in response to the continuous compressive load caused by the tire inflation force) .

As shown in Figure 3, a plurality of radial grooves RG are formed about the circumference of the bead portion of tire T2A at approximately evenly spaced intervals. As shown, four straight radial grooves SRG are formed about the periphery of the bead portion at approximately 90° increments. Of course, less or more than four radially extending grooves may be provided in the tire bead flange. It is contemplated that a sufficient number of radial grooves RG may eliminate the need for the circumferential groove CG, each radial groove venting air trapped between the tire bead flange and the wheel rim flange near its location. On the other hand, only a single radial groove is required if a continuous circumferential groove, connecting with the radial groove, is utilized.

The circumferential groove CG and the one or more radially extending grooves RG are formed in the bead flange during the curing/forming process of the tire T2A. The dimensions of the grooves are chosen to effectively collect and vent air trapped between the tire bead flange and the wheel rim flange, without providing a leakage path through which air within the body of the tire may escape during the serviceable lifetime of the tire. The depth and width of the circumferential groove is approximately .030 inch. Similarly, the depth and width of each of the radial grooves is also approximately .030 inch. Generally, the width and depth dimensions of the radial and circumferential grooves may be in the range of .005 inch to .045 inch. Of course, these dimensions are merely exemplary, and it is contemplated that circumferential and radial grooves of other dimensions could be provided. The presence of the radial grooves RG in tire T2A does not significantly increase the risk of leakage of the inflation air contained within the tire body at the location of the bead flange for at least two reasons. First, the bead flange-rim flange interface is not the primary sealing surface of the tire/rim assembly. Primary sealing of the tire/rim is provided by the radial surface interface of the tire and rim, caused in part by the compressive force of the bead ring BR. Moreover, the depth and width dimensions of the radial grooves may be tailored accurately enough to insure that the grooves will close over time (i.e. compression set) in order to prevent leakage.

Although the tire T2A is mounted to the rim R using known methods, the resulting seal between the bead flange BF and the rim flange RF is improved over the seal achieved, for example, with the known tire/rim assembly of Figure 1. Once the uninflated tire T2A is initially installed onto the rim, such that the inner and outer bead flanges are between the inner and outer rim flanges, the tire begins to be inflated. Although the following description describes the outer tire/rim flange interface, the inner tire/rim flange interface functions similarly.

Initially, the outer bead portion BP moves laterally outward to the position of the safety hump SH. As the tire T2A continues to inflate, the air pressure increases to a magnitude sufficient to force the bead portion over the safety hump. However, even after the bead portion overcomes the safety hump, the radial surface RS of the tire T2A must overcome friction created at the tire and rim radial surface RS interface in order to move further laterally outward with respect to the rim. The friction, as explained above, is created primarily by the radially inward compressive force of bead ring BR.

Also as explained above with respect to Figure 1, because of the frictional force at the radial surface RS interface of the tire and the rim, and further because the sidewall SW portion of the tire is thinner and less rigid than the bead portion, the radially outward portion of the bead flange typically meets the radially outward portion of the rim flange before the tire is completely seated onto the rim. However, because of the presence of the circumferential groove CG and the connecting radial grooves RG in tire T2A, any air which is initially trapped in the void between the bead and rim flanges (see Figure 1) is (i) collected by the circumferential groove CG and (ii) vented outside the tire by the radial grooves RG. Because no air remains trapped between the bead and rim flanges, no compressive force develops as the tire continues to be inflated which would otherwise oppose the outward lateral movement of the lower portions of the bead flange to prevent the lateral surfaces LS of the rim and bead flanges to mate completely. In this manner, the tire bead flange is completely seated onto the rim flange.

Because the tire bead flange is completely seated onto the tire rim flange, the problems associated with improper seating of the tire on the rim are eliminated with the present invention. Specifically, in testing the tire for force variation uniformity, the chances of inappropriately rejecting or improperly grinding a tire that falls within prescribed force variation specifications are minimized when the tire is properly seated on the rim. In addition, a properly seated tire is less likely to suffer from the adverse performance characteristics exhibited by tires having tread shoulders which are pulled radially inward due to improper seating. Still further, providing more surface contact between the tire and the rim reduces the opportunity for rotational slippage of the tire with respect to the rim, correspondingly reducing the chances of disrupting the balancing of the wheel and tire assembly. With respect to this surface contact, to additionally effect the seal between the radial surfaces of the tire and rim, the radial surface of the tire RS located laterally inward of the bead heel is initially tapered at about 8° radially inward, starting at about point Y of Figure 2A, and then further tapered at about 22° near the bead toe BT of the tire T2A.

Figure 4 shows another form that the radial grooves RG of the tire T2A may assume. As shown in Tire T2A2, the four straight radial grooves SRG are replaced with four curved radial grooves CRG formed about the periphery of the bead portion at approximately 90° increments. Like the straight radial grooves, less or more than four curved radial grooves may be provided in the tire bead flange.

Figure 5 shows another alternative embodiment of the present invention. In addition to being provided with the circumferential groove CG and the one or more radial grooves RG, like the tire T A of Figure 2A, the inner and outer bead portions of the tire T3 are provided with a chamfered heel CH. The chamfered heel is obtained by forming a beveled (chamfered) portion of the tire at the location of the bead heel BH. The preferred angle of the chamfer, as measured from the rim flange is in the range of 30° - 60°, and is preferably about 45° . Because the radial surface RS of the tire and rim is pitched at a 5° incline, the angle of the chamfer with respect to the radial surface RS is approximately in the range of 25° - 55°, and is preferably about 40°.

By chamfering the bead heel of the tire T3 as shown in Figure 5, the surface area of the radial surface RS of the tire which contacts the radial surface RS of the rim is lessened. As a result, the total frictional force developed at the rim/tire radial surface interface is diminished, so that the inflation force developed in the tire may more easily overcome this developed frictional force. In this way, despite the relative thinness of the sidewall SW portion of the tire with respect to the bead portion BP, the radially outward portion of the bead flange is less likely to meet the radially outward portion of the rim flange before the tire is completely seated onto the rim. Even if the radially outward portion of the bead flange does meet the radially outward portion of the rim flange before the tire is completely seated onto the rim, because of the reduced friction resulting from the chamfered heel CH, the bead portion BP of the tire is more likely to have moved further laterally outward than if the heel were not chamfered, thereby reducing the amount of air trapped between the bead and rim flanges. Any air which does become so trapped, however, may be removed by the combination of the circumferential and radial grooves in the tire bead flange, as fully explained above.

Accordingly, the preferred embodiment of an improved tire, having a vented bead ring flange for venting trapped air, has been described. With the foregoing description in mind, however, it is understood that this description is made only by way of example, that the invention is not limited to the particular embodiments described herein, and that various rearrangements, modifications and substitutions may be implemented without departing from the scope of the invention as hereinafter defined by the following claims and their equivalents.

Claims

We claim :

1. A tire, comprising: a tread portion; an inner sidewall portion extending from said tread portion radially inward toward an inner bead ring portion; an outer sidewall portion extending from said tread portion radially inward toward an outer bead ring portion; said inner and outer bead ring portions providing mating surfaces, respectively, for mating with corresponding inner and outer surfaces of a wheel rim to which the tire is mounted, at least one of said inner and outer bead ring mating surfaces provided with at least one groove formed therein and extending toward its respective sidewall portion.

2. The tire of claim 1, wherein both of said inner and outer bead ring mating surfaces are provided with said at least one groove formed therein and extending toward said inner and outer sidewall portions, respectively.

3. The tire of claim 2, wherein said inner and outer bead ring mating surfaces are also provided with a generally circumferential groove extending generally about the periphery thereof, said at least one groove connecting with said circumferential groove and extending radially outward therefrom.

4. The tire of claim 3 wherein said generally circumferential grooves are continuous about the peripheries of their respective bead ring mating surfaces.

5. The tire of claim 3, wherein said at least one groove comprises four grooves oriented about the periphery of said bead ring mating surfaces at approximately 90° spaced intervals.

6. The tire of claim 3, wherein said at least one groove connecting with said circumferential groove is generally straight and extends directly radially outward from said circumferential groove.

7. The tire of claim 3, wherein said generally circumferential grooves are discontinuous about the peripheries of their respective bead ring mating surfaces.

8. The tire of claim 7, wherein each of said discontinuous circumferential grooves connects with a corresponding radially extending groove.

9. The tire of claim 3, wherein said at least one groove and said circumferential groove are of a depth of approximately between .005 inch and .045 inch and a width of approximately between .005 inch and .045 inch.

10. The tire of claim 9, wherein said at least one groove and said circumferential groove are of a depth of approximately .030 inch and a width of approximately .030 inch.

11. The tire of claim 3, wherein said inner and outer bead ring portions are each provided with a sealing surface, each of said sealing surfaces providing a chamfered edge portion, said sealing surface adapted to seat against a rim to which the tire is mounted at locations other than said chamfered edge portion.

12. The tire of claim 11, wherein said chamfered edge portions connect said sealing surfaces to said bead ring mating surfaces.

13. The tire of claim 11 wherein said chamfered edge portion lies at an angle of between 25° and 55° as measured with respect to said sealing surface.

14. The tire of claim 3, further comprising a circumferential ridge disposed adjacent to and radially inward from said circumferential groove, said circumferential ridge extending laterally outward from said bead ring portion mating surface.

15. A method of removing trapped air between bead ring portions of a tire and corresponding mating portions of a rim upon which the tire is mounted, the tire having a body including a tread portion and inner and outer sidewall portions extending radially inward therefrom toward, respectively, the inner and outer bead ring portions, said method comprising the steps of :

(i) forming in said inner and outer bead ring portions at least one groove which extends toward its respective sidewall portion; (ii) mounting the tire while uninflated onto the rim; (iii) inflating the body of the tire so that said inner and outer bead ring portions expand laterally outward toward said corresponding mating portions of the rim; and

(iii) venting air which is trapped between said inner and outer bead ring portions and said corresponding mating portions of the rim through said at least one groove to an area outside of said tire body.

16. The method of claim 15, wherein said step of forming said at least one groove further comprises forming a generally circumferential groove extending generally about the peripheries of said inner and outer bead ring portions, said circumferential groove connecting with said at least one groove.

17. The method of claim 16, wherein said generally circumferential grooves are continuous about the peripheries of their respective bead ring portions.

18. The method of claim 17, further comprising the step of collecting in said continuous circumferential grooves air which is trapped between said inner and outer bead ring portions and said corresponding mating portions of the rim, prior to venting said trapped air through said at least one groove to an area outside of said tire body.

19. The method of claim 18, wherein said step of forming said at least one groove comprises forming four grooves oriented about the peripheries of said bead ring portions at approximately 90° spaced intervals.

20. The method of claim 18, wherein said at least one groove connecting with said circumferential groove is generally straight and extends directly radially outward from said circumferential groove.

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