Vehicle Wheel Equipped With Pneumatic Tire

The present invention relates to a vehicle wheel equipped with a pneumatic tire which is only slightly outwardly arched or crowned and which has a carcass and a centrally arranged tread strip.

With heretofore known pneumatic tires of this type, the tread strip, which comes into contact with the roadway, or the contact surface formed by the tread strip, are comparatively wide. This is made possible due to the comparatively large axial reach or extension of the tire body. Thus a correspondingly wide contact surface for the pneumatic tires results. However, a corresponding widening or expanding of the contact surface occurs owing to the inevitable flattening of the tire body at the ground contact point. This expanding results in corresponding deformations of the carcass layers, leading to a hardening of the tire while the latter yields at the flattening ground contact areas.

It is an object of the present invention to so improve vehicle wheels equipped with pneumatic tires, that they have a soft spring characteristic .

This object and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawing in which:

FIG. 1 is a partial section through a non-deformed pneumatic tire according to the present invention.

FIG. 2 shows the partial section of FIG. 1 with the ground contact area under load or stress.

FIG. 3 is a top view of the tire of FIG. 1.

FIG. 4 shows a modification of the rim of the tire of FIGS. 1-3.

The present invention is characterized primarily in that the tread strip, the sides of which are markedly defined, has a width essentially one third the freely extended axial length of the tire body. In addition thereto, the bulging or crown area of the tire, when its respective ground contacting surface is not flattened, is so slight that those strength carriers of the carcass which are arranged radially inwardly of the marginal areas or shoulders of the tread strip form with the axis of rotation of the tire only an angle of from 5.degree. to 15.degree.. Beyond that, the tire is operated at such an inner pressure that under the prescribed axle load the carcass is at the ground contacting area concavely so deflected that the carcass strength carriers with the axis of rotation of the vehicle wheel or of the tire likewise form an angle of only from 5.degree. to 15.degree.. Consequently, the carcass strength carriers form a comparatively small angle radially inwardly of the tread surface margins, that is an angle of about 10.degree. to 30.degree.. Since in addition thereto, during the flattening action and during the start of the formation of the ground contact area, the width of the tread strip surface is not or not greatly enlarged, a comparatively highly soft elasticity or resilience results, which is far greater than that encountered with tires with which the width of the tread strip surface expands while a tire section is flattening. It is important in this connection that the soft resiliency of the tires be ensured, although the volume of the tire cavity is small and the pressure above atmospheric pressure in the hollow chamber of the tire is considerably greater than is the case with pneumatic tires having a U-shaped cross section.

Referring now to the drawing in detail, the arrangement shown therein comprises a rim 1 of steel or the like with a slightly concave middle section 2 between lateral marginal sections 3 which taper conically outwardly. The transition between the marginal sections 3 and the middle section 2 is a circular projecting nose 4. The area at the outer perimeter of the marginal or rim sections 3 and 4 forms the seat area for the tire beads 5 with steel cores 6 for anchoring two carcass layers 7 and 8, the cords 9 of which cross each other and form angles of from 50.degree. to 60.degree. with the cross sectional direction of the tire in such a way that the cords 9 of adjacent layers 7 and 8 form angles of from 60.degree. to 80.degree. with one another.

Between the two bead parts 5 there is located the dynamically stressed tire body, which is primarily deformed during operation of the tire. The tire body extends from one nose 4 to the other and has the width B. The tread strip 10, which is centrally located on the tire body, has lateral, sharply defined edges or shoulders 11 and a width p which is approximately one third the width B. The sharp edges 11 insure that the width of the tire contact surface upon the ground contact area does not vary.

The pressure within the tire cavity is about 3 to 5 atmospheres above atmospheric pressure. At this pressure, the freely deformable section of the tire body or its carcass layers 7, 8, which are between the two noses 5, are slightly crowned or bulged so that radially inwardly of the contact surface edges 11 the two carcass layers 7, 8 form an angle of about 10.degree. with the tire cross direction running parallel to the axis of rotation of the wheel or tire. This angle is designated a. The angle formed by the tapering marginal sections 3 with the axis of rotation of the tire is designated c and may be about 10.degree..

When the tire flattens or deflects inwardly under the prescribed load, that portion of the tire body which is located between the two noses 4 is arched inwardly in such a way that the two carcass layers 7, 8 are in a concave position as shown in FIG. 2, also forming an approximately 10.degree. angle with the tire cross sectional direction. This angle is designated b. In view of the sharp edges 11, only a relatively small angle variance of the carcass layers 7, 8 occurs with regard to the cross sectional direction of the tire.

The tire cavity 13, which has a nearly lens-shaped cross section, may also have a varied cross sectional shape. If necessary, an elastic projection 2a may also be centrally provided on the rim 1 in order to stop or absorb shocks or undue forces acting upon the tire body. This projection may be of elastic steel welded to rim 2.

The pneumatic tire described may also be provided with a side-stabilizing belt radially inwardly of the tread strip 10. However, such a belt is not absolutely necessary since the tire body has an essentially cylindrical form which is only nominally altered during its flattening action.

It is, of course, to be understood that the present invention is by no means limited to the specific showning in the drawing but also comprises any modifications within the scope of the appended claims.