DE2420965A1 - VEHICLE AIR TIRES - Google Patents

Description

1796

PATENT LAWYERS

DR.-ING. R. DÖRING DIPL.-PHYS. DR. J. FRICKE

BRAUNSCHWEIG MUNICH

Uniroyal, Clairoix / France

"Pneumatic vehicle tires"

The invention relates to a pneumatic vehicle tire with a profiled one Tread section in which solid surface areas are delimited by recessed or grooved surface areas whose size ratio per unit area in the lateral zones of the tread is different from that in the central zone deviates. This tire can in particular be a radial layer tire, possibly with a belt insert.

It is known that the service life of a pneumatic vehicle tire depends essentially on the wear and tear of the tread. Included the tire becomes unusable the moment the solid and recessed sections are molded into the tread are no longer recognizable on the entire surface of the tread section. However, the shoulder areas are inclined the tread, i.e. the lateral zones of the tread surface, to wear out faster than the central or middle zone. The consequence is that in the case of a Standard running surface, which has recesses in

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in the form of grooves of constant depth and substantially have identical quantity or density in the different areas of the surface, the grooves mentioned locally in the the aforementioned lateral areas disappear as a result of wear and tear on the raised or solid areas that are located between the grooves. On the other hand, profiled parts remain in the middle zone of the surface. Because of the fact that the pneumatic vehicle tires no longer have sufficient grip in the stage of wear of the tread, the road grip and tracking ability of a vehicle that is equipped with such tires, extremely small, so that it is necessary to give up the further use of the tires for safety reasons. It It can easily be seen that, if it were possible, this selective wear would be due to the lateral zone of the tread avoid, the service life of a pneumatic vehicle tire is increased considerably.

It has already been proposed to avoid this selective wear by making grooves of greater depth in the provides the aforementioned lateral zones. The depth in this area can be 10% greater while at the same time substantially the same density of the groove is maintained along the entire surface of the tread. The wear and tear of the The lateral zone of the tread area is corrected in this way. In view of the fact that there is also it is necessary to increase the thickness of the tread in the said lateral zones, so that there are deeper grooves

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can accommodate, it should be noted that the addition of rubber compound or the like. Material leads to the result that the Heat generated inside the tread is much more difficult to dissipate in said lateral zones, which leads to the known dissolution or detachment of the edges of reinforcement belts and leads to increased resistance while driving. In this way, the life of the tire is nevertheless reduced due to circumstances other than those mentioned above selective wear. With this measure nothing is gained with regard to the service life of the tire.

There is also the option for the purpose of correcting the selective wear of the lateral zones of the tread to provide a constant thickness, or depth, of the grooves, so that the Avoiding the need for a thickening of the lateral zone, while at the same time distributing these grooves in such a way become that they are completely absent in the peripheral zones or outer zones or have a lower density or number than in the middle zone. Pneumatic vehicle tires that are constructed according to this principle, however, have little practicality Interest in view of the fact that their liability is essential is reduced so that the wheels can easily skid. In addition, due to the small number of grooves In certain zones the water can be drained with much greater difficulty if a vehicle is in rainy weather moves. In addition, the heat generated during the ride at the height of the tread is not dissipated as well, so

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that the properties of the tire as well as its service life suffer.

It is the object of the present invention to provide a pneumatic vehicle tire of the type described in more detail at the beginning in such a way that its service life is significantly increased and the selective Wear of the tire surface is significantly reduced, without affecting the other properties of the tire, in particular its adhesion and its ability to reliably dissipate both water and heat will suffer.

This object is achieved according to the invention in that the value the product of the size ratio of the solid surface areas to the recessed or grooved surface areas a localized area of the tread and the depth of the recesses in this area in the lateral zones greater than 100/2 but not greater than $ 130 of the concerned Value in the middle zone. Advantageously, the value of the product mentioned increases from the central zone towards gradually towards the lateral zone.

The aforementioned condition can be obtained by making either deeper grooves in the lateral zones or in the In contrast, it provides deeper grooves in the central zone of the tread, by selecting the appropriate location Value of the ratio of the solid or raised surface areas to the area of the recesses of the tread.

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In other words, if one uses the letter r to denote the value of this ratio and the letter ρ denotes the Depth of the grooves denotes and if one continues to use the indices 1 and m of these sizes, each indicating the lateral zone or assumes the middle zone of the tread, according to the invention the following inequality is obtained:

^p m ^r m < ^p l ^r l <1.3. P _m r _m (1)

It can be seen that this relation receives the following three cases as a variable of the respective values of p _m and p ^ on the one hand and of r _m and v ^ on the other hand:

^r m

■ m

These three basic cases, which are given above, correspond to the three exemplary embodiments, which are explained in more detail below:

In a first embodiment of the invention, those are above mentioned recesses or grooves in the lateral zone deeper than in the central zone of the tread, while at the same time the ratio of the area of the raised areas to the area

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the recesses is larger in the lateral zones.

According to another embodiment of the invention, the aforementioned recesses in the lateral zone are deeper than in the middle zone of the tread, while at the same time the ratio of the raised areas to that of the recesses is smaller than is in the side zone.

In a third embodiment of the invention, the aforementioned recesses are less deep in the lateral ones Zones than in the central zone of the tread, while at the same time the ratio of the raised area to the recessed Area in the lateral zones is larger.

It is easy to see and will be explained in more detail below that the local value of the product p.r is simultaneous with the volume the rubber substance or mass increases, from the new condition of the tread to a condition in which the profiling disappears in the area in question, becomes worn out. With the increase in this value of the product in the transition from the central zone to the side zone it thus becomes possible for the wearable rubber volume in the side zone to be larger is considered in the middle zone.

In accordance with a preferred embodiment of the invention, the tread faces essentially in the longitudinal direction extending grooves which intersect with substantially radially extending grooves. These grooves determine preferentially

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wise a geometric pattern that is divided into different longitudinal zones of the tread and this is accompanied by a gradual increase in the dimensions of each pattern from the central one to the aforementioned lateral zones. The grooves can be of variable or constant width. The grooves can also a plurality of continuous geometric configurations determine which are essentially identical in different successive transverse zones of the tread repeat. Each configuration is formed by a sequence of identical or similar patterns of a size, which are from the central zone grows towards the lateral zone of the tread, the grooves being constant or variable Width are.

The invention is explained in more detail below with reference to schematic drawings of several exemplary embodiments.

Show it:

Fig. 1 is a plan view of a section of the surface of a Tread of the usual known embodiment.

Fig. 2 shows a cross section along the section line II-II of Fig.l.

3 and 4 sections of surfaces of two other possible ones Types of treads.

5 shows a top view of a section of a tread element, only the structure of the solid or raised and the recessed areas of this surface

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are reproduced in a locally limited zone of this area in order to obtain an exact definition of the ratio of fixed areas to excluded areas to enable.

6a shows a tire according to the invention in a perspective illustration .

6b shows a plan view of a section of a tread according to two embodiments of the invention.

6c and 6d cross sections of the running surface for the two exemplary embodiments, the section being taken along the section line 6c-6c of FIG. 6b.

7a shows a plan view of a section of a running surface according to two other embodiments of the invention, and

7b and 7c are cross-sections through the running surface according to FIG Reproduction of the two exemplary embodiments, the sections each along the section line 7b-7b in FIG. 7a are laid.

As can be seen from FIGS. 1 and 2, the running surface 1 comprises a plurality of grooves or recesses along its upper side 2, which in the example shown comprise two grooves 4 1, which are arranged along the lateral zones of the treads, as well as two grooves 4 m in the central or middle area of the tread are provided. As can be seen from Figure 2, the depth of the grooves 4 1 of the lateral zones is greater than the depth of the grooves 4 m of the middle zone. This leads to the fact that the

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The tread in the shoulder areas must have a thickness e which is greater than the thickness e ^{f of} the central area of the tread. As mentioned above, such a tread design has the disadvantage that it becomes difficult to dissipate the heat developed in the area of the shoulders, which leads to a detachment of the edges of a reinforcement belt, not shown, which is arranged between the tread and the tire carcass.

In the case of the embodiments shown in FIGS. 3 and 4 are, it is assumed that all the grooves have the same depth, and that there is selective wear of the lateral Zone of the tread compensated for by modifying the distribution of the grooves accordingly.

Thus, in the tread part of Figure 3, the arrangement is made so that that three equally spaced grooves 5 are provided in the central zone of the tread 6, while the lateral zones 7a and 7b are completely free of such grooves,

In the exemplary embodiment according to FIG. 4, the distance between two successive grooves 8 gradually increases as the transition from the middle zone to the lateral zones 9a and 9b of the tread 10.

In FIG. 5, a locally delimited zone 11 of the tread area 12 is shown. It can be a tread act of any type and any profile.

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241 & 965

- ίο -

A certain pattern is shown in zone 11, which consists of fixed sections 13 (i.e. raised or protruding sections) and consists of recesses or hollow sections (in the illustrated case in the form of grooves). If you are with the Letters a, for example a predetermined unit of length such as inches, the dimension of the zone 11 in the longitudinal direction of the tread and with the letter b, for example in the same unit of length, denotes the dimension of zone 11 in the transverse direction,

with S_ the area of the raised sections 13 and with S. the P °

Area of the recessed areas 14, the value of the ratio of the solid or raised area areas can be used express the excluded areas by the following equation:

S ^ ab - S _{n Qh} r = _l = ^G _ = ^ -1 (2)

^S C ^S C ^S C

The volume of the rubber material that can be removed by wear from the raised areas to the bottom of the grooves Ik can be expressed by the equations:

V = S _p . ρ (3)

or V = a. b. ρ, r
1 + r

In these equations, the letter ρ represents the

average depth of the grooves in the local area under consideration.

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One can easily check with the help of the formula (4) that the amount of material that is needed to disappear the molded grooves can be worn in a given local zone of the tread, in direct proportion to the average depth of the recesses, and that this amount of material varies in the same direction as the ratio of solid area to recessed Area (r).

In the embodiments of the invention as shown in FIGS. 6b and 6c as well as in FIGS. 6b and 6d are shown, the grooves 15 of the surface 16 of the running surface 17 form geometrical Template. In the present case, the grooves form rectangles, which are located in the various in the circumferential direction or in the longitudinal direction repeat the running zones ABCD of the surface 16. At the same time, the size of this pattern increases from the central zone of the Surface gradually increases in the direction of the edge zones. In addition, the profile in these embodiments includes along the longitudinal center line of the tread an additional groove 18. All grooves 15 have the same width, so that the ratio from solid surfaces to recessed surfaces gradually from the central zone towards the lateral zone of the surface 16 increases. The depth of the grooves 15 is gradually variable, it being assumed that the maximum depth value is either lateral Zones is, as indicated in the embodiment according to Figure 6b and 6c, or in the middle zone, as is indicated in the embodiment of FIGS. 6b and 6d.

It should be noted that the top view of the

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Pattern is the same in both embodiments, so that Fig. 6b has not been drawn twice, but for both Embodiments is equally relevant. The tread patterns of the two exemplary embodiments are independent of this 6b and 6c as well as FIGS. 6b and 6d in full correspondence with the above relationship (1), as it is repeated again below:

Pm ^r m

It can be seen that the pattern of Fig. 6b comprises essentially longitudinal grooves formed with essentially radially extending grooves Grooves, the latter causing water to drain towards the lateral zones of the tire when driving facilitate wet road.

In the exemplary embodiments according to FIGS. 7a, 7b and FIGS. 7a, 7c, the recesses on the surface 19 delimit two crenellated lines 20a and 20b in the central zone of the running surface 21, which are oriented in the longitudinal or circumferential direction. Furthermore, the recesses comprise a plurality of grooves of continuous geometric configuration, which are _{repeated in an identical manner in successive transverse zones Z 1} JZ ₂₃ Z, and Z ₁ ^ of the tread. The continuous geometric configuration 13 is formed here by a sequence of crenellated patterns which increase from the central to the lateral zones of the tread. In other words, this means that the size t of a pinnacle in the transverse direction and the size 1 of a pinnacle

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increases in the circumferential direction if you successively the different Perimeter zones ABCD penetrated. You may find, that in the embodiments of FIGS. 7a, 7b and 7a, 7c the width of the grooves need not necessarily be constant. As far as the depth of the grooves is concerned, this can be fortschia.tend and gradually increase from the central zone to the lateral zone, which is a preferred embodiment and. in the Pig. 7a and 7b is shown, or the groove depth, in contrast, can be from the central zone in the direction of remove the lateral zones, as indicated in FIGS. 7a and 7c. Regardless of this, the variation in the depth of the grooves is such that in each case the above-mentioned relationship (1) is satisfied, i.e. that the volume of the raised zones per unit area of the surface of the tread is greater in the lateral Zones than is in the middle zone. This can be done either by gradually changing the depth or by a discontinuous one Change can be achieved. It can be seen that the characteristics of the shape and size of the grooves 20a and 20b are in this case selected in such a way that the product pi * in the central zone of the tread is a minimum owns.

It can be seen that the pneumatic tires, their treads are in accordance with one of the exemplary embodiments according to the figures shown, create the possibility of to correct the selective wear of the shoulders of the treads in such a way that the disappearance of the raised

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Areas essentially simultaneously in the central zone and occurs in the two lateral zones of the surface. This makes it possible to significantly extend the service life of such tires to enlarge, ζ, .Β. to double.

It should be seen that, as explained above with reference to FIG. 6b, Pig.7a is also used for two exemplary embodiments, the differences of which are evident from FIGS. 7b and 7c.

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Claims (9)

Patent claims 1. Pneumatic vehicle tires with a profiled tread section - "" ---- 'section, in which solid or raised surface areas are limited by recessed or grooved surface areas whose size ratio per unit area in the lateral zones of the tread is different from that in the central zone differs, characterized in that the value of the product (rp) from the size ratio (r) these surfaces of a locally limited area of the running surface (16) and the depth (p) of the recesses (15) in this area in the lateral zones is greater than 100? but not greater than 130? of the relevant value in the middle zone is. 2. Pneumatic vehicle tire according to claim 1, characterized characterized in that the value of the product (rp) from the central zone to the lateral zones of the tread gradually increases. 3. Pneumatic vehicle tire according to claim 1 or 2, characterized in that the recesses in the lateral zones are deeper than in the central zone of the tread, and that the value of the local ratio the raised area to the recessed area is larger in the lateral zones than in the central zone. 409847/0369 4. Pneumatic vehicle tire according to claim 1 or 2, characterized characterized in that the recesses in the lateral zones have a shallower depth than in the middle Zone of the tread, and that the value of the local ratio of raised areas to recessed areas is larger in the lateral zones than in the central zone. 5. Pneumatic vehicle tire according to claim 1 to 4, characterized in that the recesses are substantially form a pattern of longitudinal grooves and transverse grooves which communicate with each other stand. 6. Pneumatic vehicle tire according to claim 1 to 5 »thereby gekennz eichnet that the geometric pattern of the recesses is in different peripheral zones of the tread repeated in conjunction with a gradual increase in the dimensions of this pattern in the transition from the central one Zone to the lateral zones of the tread. 7. Pneumatic vehicle tire according to claim 1 to 4 or 6, characterized in that the recesses are grooves and form a plurality of continuous, geometric configurations which are essentially _{repeated in different successive transverse zones (Z 1} to Z ₁ ^) of the tread each geometric configuration forming similar patterns, the size of which at the transition 409847/0369 from the central zone to the lateral zones of the tread increases. 8. Pneumatic vehicle tire according to claim 7, characterized in that the continuous geometric configurations have a crenellated course have, the dimensions of the battlements both in the circumferential direction and across it at the transition from the central one Increase zone to the lateral zones of the tread. 9. Pneumatic vehicle tire according to claim 5 or 6, characterized in that the recesses are a Network of contiguous, circumferential and transverse to this form running grooves of rectangular course, where the circumferential dimensions and the dimensions transversely thereto of the individual rectangular fields at the transition from the central one to increase towards the edge zones. 409847/0369 Blank page