KR101076620B1 - Non-pneumatic tire - Google Patents

Abstract

The structural support tire includes an outer annular band and a plurality of web spokes extending longitudinally across and from the annular band and radially inwardly and secured to the wheel or hub. The annular band further comprises a shear layer, at least one first film attached to the radially inner extent of the shear layer, and at least one second film attached to the radially outer extent of the shear layer. Preferred web spokes have cuts transverse to the annular band. This cut has a shape formed by straight line segments connected by a joining radius. The shape of this cut portion has a height HC and a maximum depth D that is 5% or more of the height N and 20% or less of the maximum width W. The shape is formed by a tangent to the shape with respect to the horizontal line and has an angle alpha that is at least 10 ° at the radially outermost and radially innermost sides of the shape. The minimum radius of curvature RR of the shape is at least 20% of the height HC of the cutout.

Non-pneumatic tires, structural support tires, web spokes, annular bands, shear layer

Description

Non-Pneumatic Tires {NON-PNEUMATIC TIRE}

1 is a view from the equator plane of the tire of the invention under load;

2 is a cross-sectional view of a tire according to the present invention as seen from the meridian surface.

FIG. 3 shows the ground reaction force for reference homogeneous bending not showing shear deformation. FIG.

4 shows the ground reaction force for the annular band according to the invention.

FIG. 5 is a view of the tire of the present invention with the load applied, showing in reference dimensions to illustrate the load bearing mechanism;

FIG. 6 is a view of the tire of the present invention showing the transverse shape of the web spokes shown in the meridion plane. FIG.

FIG. 7 is a cross-sectional view showing the arrangement of web spokes in the X pattern of the tire as seen from the equator plane. FIG.

8 is an illustration of an alternative arrangement of web spokes in zig-zag as seen from the equator plane.

9 is an illustration of an arrangement of web spokes in an axial pattern inclined radially toward the axis of rotation.

10 shows an alternative chevron arrangement of web spokes viewed radially towards the axis of rotation.

FIG. 11 shows an alternative arrangement for alternating circumferential and axial alignment of web spokes viewed towards the axis of rotation. FIG.

FIG. 12 shows the intensity of counterdeflection seen from the equator plane. FIG.

13 is a diagrammatic representation of the relationship between contact area, contact pressure and vertical load of a tire according to the present invention.

14 is a diagram schematically showing the relationship between the contact pressure, vertical strength and reverse deflection strength of a tire according to the present invention.

The present invention relates to a non-pneumatic and structurally supported tire or tire / wheel assembly. In particular, the present invention relates to a non-pneumatic tire having pneumatic tire type performance, which serves to support the load with its structural parts and serves to replace the pneumatic tires.

Pneumatic tires have load bearing, road shock absorbing and force transmission (acceleration, braking and steering) capabilities that make them suitable for many vehicles, most notably bicycles, motorcycles, cars and trucks. These capabilities have also become highly advantageous with the development of cars and other vehicles. The shock absorbing capability of pneumatic tires is also useful in carts carrying other applications, for example sensitive medical or electrical equipment.

Conventional non-pneumatic tires, for example solid tires, spring tires and cushion tires, lack the performance advantage of pneumatic tires. In particular, solid tires and cushion tires rely on the compression of ground contacts for load bearing. Tires of this kind are heavy and rigid and lack the shock absorbing capability of pneumatic tires. When made to be more resilient, conventional non-pneumatic tires lack the load bearing capacity or durability that pneumatic tires have. Thus, except in limited circumstances, known non-pneumatic tires have not been widely used as a replacement for pneumatic tires.

Non-pneumatic tires / wheels with performance characteristics similar to those of pneumatic tires will overcome many deficiencies in the art and will be a welcome improvement.

A non-pneumatic tire / wheel that is structurally supported in accordance with the present invention is characterized by an annular band for supporting the load on the tire and a plurality of tensions that transfer the load force in tension between the annular band and the wheel or hub. Web spokes. As used herein, a tire or tire wheel means a structure according to the invention as opposed to a mechanism in a pneumatic tire for supporting load alone through structural features and without support from internal pneumatic pressure. do.

According to one useful embodiment, the present invention provides an outer annular band, a plurality of web spokes extending inwardly transversely across the reinforcement annular band and radially from the reinforcing annular band, and a plurality of web spokes. And means for interconnecting the wheel with the spokes having a maximum width W and a radial height N. The web spokes have a cross-sectional shape such that each web spoke has a minimum width in the middle between the outer annular band, the plurality of web spokes and the means for interconnecting the wheel. Many web spokes have a cutaway section transverse to the band. This cut | disconnected part has a shape containing height HC and the maximum depth D which becomes 5% or more of height N and 30% or less of the maximum width W. This shape has an angle alpha formed by a line tangent to the shape with respect to a horizontal line that is at least 10 degrees in the radially outermost and radially innermost range. The minimum radius of curvature RR of this shape is at least 20% of the height N of the spokes. The annular band further comprises at least one first membrane attached to the radially inner range of the shear layer, and at least one second membrane attached to the radially outer range of the shear layer, each of these membranes being a shear layer. It has a longitudinal tensile modulus that is greater than the shear modulus of.

The particular shape becomes a function of the design variable of the spokes themselves. Important geometrical elements are the tangential angle between the horizontal line in the radially outer and radially inner range of the spoke, the maximum transverse depth of the shape and the minimum radius of curvature of the shape. The method of determining the geometric elements of the transverse shape is

(a) the width W and height N of the web spokes, the radial offset Q of the shape and the transverse direction of the shape greater than 5% of the height N and less than 30% of the width W of the shape; Specifying a depth D,

(b) determining a calculated value of the tangential angle alpha defined by the tangent between the shape and the intersection of the horizontal line;

(c) comparing the calculated value of the tangential angle alpha with a predetermined minimum value and setting alpha to be the greater of the calculated value or the minimum value,

(d) determining a calculated value for the minimum radius of curvature RR of the transverse shape;

(e) comparing the calculated value for the radius with a predetermined minimum value,

(f) if the calculated value is greater than the minimum value, setting the radius RR to the larger calculated value.

If the minimum radius value calculated from the steps is less than the minimum criterion, the method further decreases the value of alpha and repeats steps (c) to (f) until the calculated radius RR is greater than the minimum value. Can be repeated.

The structural support tire of the present invention does not have a cavity for receiving low pressure air, thus eliminating the need to form a seal with the wheel rim to preserve the internal air pressure. Structural support tires therefore do not require wheels as understood in pneumatic tire technology. For the purposes of the following description, the terms "wheel" and "hub" refer to any device or structure for supporting a tire and for installation on an axle, and are understood to be interchangeable herein.

According to the invention, the annular band comprises a shear layer, at least one first film attached to the radially inner extent of the shear layer, and at least one second film attached to the radially outer extent of the shear layer. . The membranes have a circumferential tensile modulus that is sufficiently larger than the shear modulus of the shear layer such that the ground contact tread site under load applied to the outside is essentially the same as the ground from the circular shape while maintaining the basic constant length of the membranes. Deformed into shape. The relative displacement of the membranes is caused by the shear force in the shear layer. Preferably, the membranes comprise overlapping layers of essentially inextensible cord reinforcement embedded in an elastomeric coating layer.

The shear layer is formed of an elastomeric material such as natural or synthetic rubber, polyurethane, foamed rubber and foamed urethane, segmented copolyester and block co-polymer of nylon. Preferably, the shear layer material has a shear modulus of about 3 MPa to about 20 MPa. The annular band has the ability to bend to conform to a contact surface such as a road surface while under load from a normal circular shape.

The web spokes act as tensions to transfer the load force between the wheel and the annular band and thus support the weight of the vehicle, among other functions. Bearing force is created by tension in web spokes that are not connected to the ground contact of the annular band. The wheel or hub can be said to span from the top of the tire. Preferably, the web spokes have a high effective radial strength in the tensioned state and a low effective radial strength in the compressed state. Due to the low strength in the compressed state, the web spokes to be attached to the ground contact of the annular band are bent to absorb road impact and better fit the annular band to road surface irregularities.

Web spokes also transmit the force needed for acceleration, braking and cornering. The arrangement and orientation of the web spokes can be selected to achieve the desired function. For example, where relatively low circumferential forces are generated, the web spokes can be arranged radially and parallel to the axis of rotation. To provide strength in the circumferential direction, web spokes perpendicular to the axis of rotation may be added alternating with the axially aligned web spokes. Another alternative is to arrange the web spokes at an angle to the axis of rotation to provide strength in both the circumferential and axial directions.

To facilitate bending of the web spokes of the ground contact of the tread, the spokes may be curved. Alternatively, the web spokes may be preloaded during molding to bend in a particular direction.

The following terms are defined as follows.

"Equatorial Plane" means a plane that passes perpendicular to the axis of rotation of the tire and bisects the structure of the tire.

"Meridian Plane" means a plane that passes through the axis of rotation of the tire and also includes the biaxial axis.

"Modulus" of an elastomeric material means a tensile modulus of elasticity at 10% elongation measured at every ASTM standard test method D412.

"Coefficient" of membranes means a tensile modulus of elasticity at 1% elongation in the circumferential direction that is multiplied by the effective thickness of the membrane. This coefficient can be calculated from Equation 1 below for a conventional tire steel belt material. This coefficient is appended with a prime (') sign.

"Shear modulus" of an elastic material means a shear modulus and is defined to correspond to one third of the tensile modulus of elasticity as defined for the elastic material.

"Hysteresis" means the dynamic loss tangent (tan Δ) measured in running strain, temperature and frequency. Those skilled in the art will appreciate that the driving conditions are different from the different load and speed conditions for a particular field, such as golf carts and sports cards, and that strain, temperature and frequency may be specified for a particular field.

A view of the structurally supported elastic tire according to the invention from the equator plane is shown in FIG. 1. Structural support means that the tire supports the load by its structural parts without the support of gas inflation pressure. Structures disclosed for various variants of structurally supported elastic tires use similar basic parts. Reference numerals shown in the figures follow a consistent pattern for each variant. The figures are not drawn to scale, and the dimensions of the members have been exaggerated or reduced for clarity.

The tire 100 shown in FIG. 1 has a ground contact tread portion 105, a reinforced annular band 110 disposed therein in the radial direction of the tread portion, and transversely across and from the annular band. A plurality of web spokes 150 extending radially inwardly, and a mounting band 160 at the radially inner ends of the web spokes. The installation band 160 fixes the tire 100 to the wheel 10 or the hub. As used herein, "extending transversely" means that the web spokes 150 are axially aligned or inclined with respect to the axis of the tire. Furthermore, "extending radially inward" means that the web spokes 150 are in a radial plane in the tire axis or inclined in a radial plane. Also, as described below, the second plurality of web spokes may extend at the equator plane.

With respect to FIG. 2, which shows the tire 100 and the wheel 10 in a cross section viewed from the meridian plane, the reinforcement annular band 110 includes an elastic shear layer 120 and a radially innermost range of the elastic shear layer 120. And a second film 140 attached to the radially outermost side of the elastic front end layer 120. The films 130 and 140 have a tensile strength greater than the shear strength of the shear layer 120 such that the reinforced annular band 110 is sheared under load.

The reinforced annular band 110 supports the load on the tire. As indicated in FIGS. 1 and 5, the load L applied to the axis of rotation X of the tire is transmitted to the annular band 110 by tension in the web spokes 150. The annular band 110 acts in a similar manner to the arc and provides circumferential compressive strength and longitudinal bending strength at the tire equator surface that are high enough to act as a load bearing member. Under load, the annular band deforms at the contact area C with the ground via a mechanism that includes shear deformation of the band. This shear deformation capability provides a flexible ground contact area C that acts similarly to the shear deformation capability of a pneumatic tire, resulting in similar advantages.

3 and 4, the advantage of the shear mechanism of the annular band 110 of the present invention is that the rigid annular band 122 made of a homogeneous material, for example a metal ring, which does not allow deformation beyond the insignificant shear deformation under load. It can be understood by comparing with. In the rigid annular band 122 of FIG. 3, the pressure distribution that satisfies the force balance and bending moment conditions is a pair of concentrated forces F, one end of which is located at each end of the contact area shown in FIG. 3. It is composed. In contrast, if the annular band comprises a structure consisting of a shear layer 120, an internal reinforcement 130 and an external reinforcement 140 defining the shear deformation, according to the present invention as shown in FIG. The composite pressure distribution S on the area is generally uniform.

A beneficial result of the annular band according to the invention is that the ground contact pressure S becomes more uniform over the entire length of the contact area, which is similar to pneumatic tires and improves the function of the tire more than other non-pneumatic tires.

In typical solid tires and cushion tires, the load is supported by the compression of the tire structure in the contact area, and the load capacity is limited by the amount and type of material present in the contact area. In some types of spring tires, the rigid outer ring supports the load on the tire and is connected to the hub or wheel by elastic spring members. However, the rigid ring does not have a shear mechanism, and as explained above, the rigid ring has a concentrated ground reaction force at the ends of the contact area, which affects the ability of the tire to transmit force to the ground and to absorb the ground shock. Go crazy.

Shear layer 120 includes a layer of elastomeric material having a shear modulus of about 3 MPa to about 20 MPa. Materials considered suitable for use in the shear layer 120 include block copolymers of natural and synthetic rubber, polyurethane, foamed rubber and polyurethane, segmented copolyester, and nylon. Due to repeated deformation of the shear layer 120 during rotation under load, hysteretic losses occur that cause heat buildup in the tire. Thus, the hysteresis of the shear layer must be specified to maintain the operating temperature below the allowable operating temperature for the material used. For conventional tire materials (ie rubber), for example, the hysteresis of the shear layer should be specified to produce a temperature of about 130 ° C. or less for tires used continuously.

The tread portion 105 may not have any grooves, or as shown in FIG. 2, is essentially a plurality of longitudinally oriented ribs that form longitudinal tread ribs 109 therebetween. It may be provided with tread grooves 107. In addition, the tread 105 is shown to be flat between the edges. While this would be suitable for cars and other similar vehicles, rounded treads can be used for bicycles, motorcycles and tall two-wheeled vehicles. Any suitable tread sculpture as known to those skilled in the art can be used.

According to a preferred embodiment, the first membrane 130 and the second membrane 140 comprise essentially inextensible cord reinforcements embedded in an elastomeric coating. For a tire made of an elastomeric material, the films 130 and 140 are attached to the shear layer 120 by a cured elastomeric material. It is within the scope of the present invention for the films 130 and 140 to be attached to the shear layer 120 by any suitable method of chemical or adhesive bonding or mechanical fixation.

The reinforcing members of the membranes 130 and 140 may be any one of several materials suitable for use as tire belt reinforcement in conventional tires such as single filament or steel cord, aramid or other high modulus textiles. have. For the exemplary tires described herein, the reinforcements are steel cords, each of which consists of four wires (4 × 0.28) having a diameter of 0.28 mm.

According to a preferred embodiment, the first film comprises two reinforcement layers 131, 132, and the second film 140 also includes two reinforcement layers 141, 142.

Although the variants of the invention described herein have a cord reinforcing layer for each of the films, any suitable material requires the tensile strength, bending strength and compressive buckling resistance required for the annular band described below. It can be applied to films that satisfy the conditions for properties. That is, the membrane structure can be one of several alternatives, such as a homogeneous material (ie, a thin metal sheet), a fiber reinforced matrix, or a layer with a distinct reinforcing member.

In a first preferred embodiment, the first membrane 130 layers 131, 132 have essentially parallel cords oriented at an angle of about 10 degrees to about 45 degrees with respect to the tire equator plane. The cords of each layer have the opposite orientation. Similarly for the second film, layers 141 and 142 have essentially parallel cords oriented at an angle of about 10 degrees to about 45 degrees with respect to the equator plane. However, the codes of the various layer pairs in the film need not be oriented with each other at the same opposite angle. For example, it may be desirable for the cords of layer pairs to be asymmetrical with respect to the equator plane of the tire.

According to another preferred embodiment, the cords of at least one layer of the membrane may be at an angle of 0 ° or nearly 0 ° to the equator plane to increase the tensile strength of the membrane.

Cords of each of the layers 131, 132 and 141, 142 are typically embedded in an elastomeric coating layer having a shear modulus of about 3-20 MPa. It is preferred that the shear modulus of the coating layer be substantially the same as the shear modulus of the shear layer 120 in order to ensure that the deformation of the annular band is mainly caused by the shear strain in the shear layer 120.

The relationship between the shear modulus G of the elastomeric shear layer 120 and the effective longitudinal tensile modulus (E ' _membrane ) of the _membranes 130, 140 controls the deformation of the annular band under load. The effective tensile modulus (E ' _membrane ) with conventional tire belt material and membrane reinforcement cords oriented at least 10 ° relative to the equator plane is calculated as follows.

(1)

(One)

Where E _rubber = tensile modulus of elastomeric coating material, P = cord pace (cord centerline spacing) measured perpendicular to the cord direction, D = cord diameter, v = Poisson's ratio of elastomeric coating material , alpha = cord angle to the equatorial plane, t = rubber thickness between cables in adjacent layers.

For membranes where the reinforcing cords are oriented less than 10 ° relative to the equatorial plane, the following equation can be used to calculate the tensile modulus _E'membrane of the _membrane .

(2)

(2)

Where E _cable is the coefficient of the cable, V is the volume fraction of the cable in the _membrane , and t _membrane is the thickness of the membrane.

For films comprising homogeneous materials or fibers or other material reinforcing matrices, the modulus is the modulus of the material or matrix.

Note that the E ' _membrane is the product of the elastic modulus of the membrane and the effective thickness of the membrane. When the ratio of _E'membrane / G is relatively low, the deformation of the annular band under load is approximated by the deformation of the homogeneous band, creating a non-uniform ground contact pressure as shown in FIG. On the other hand, when the ratio of _E'membrane / G is high, the deformation of the annular band under load is basically caused by the shear deformation of the shear layer, with the films hardly extending or compressing in the longitudinal direction. Thus, the ground contact pressure becomes almost uniform as in the example shown in FIG.

According to the invention, the ratio of the longitudinal tensile modulus E ' _membrane of the _membrane to the shear modulus G of the shear layer is at least about 100: 1, preferably at least about 1000: 1.

The tire shown in FIG. 2 has a transverse shape that is flat with respect to the tread portion 105, the first film 130, and the second film 140. The strain at the site of the annular band in the contact zone C (FIG. 1) will be compressible with respect to the second membrane 140. As the vertical deflection of the tire increases, the contact length can be increased such that the compressive stress in the second film 140 exceeds the critical buckling stress and so that the longitudinal buckling of the film occurs. This buckling phenomenon causes the longitudinal extension of the contact area to have a reduced contact pressure. When buckling of the membrane is avoided, a more uniform ground contact pressure is obtained over the length of the ground contact area. Membranes with curved transverse cross-sections will better resist buckling in the contact area and are preferred when buckling under load becomes a concern.

When the precondition conditions for the longitudinal tensile modulus _E'membrane of the _membranes and the shear modulus G of the shear layer are met and the annular band is substantially deformed by shear in the shear layer, the shear modulus G and the transposition are given for a given application. The following advantageous relationship is created to specify the value of the fault thickness h.

(3)

(3)

Where P _eff = ground contact pressure, G = shear modulus of layer 120, h = layer 120 thickness, R = radial position of the second membrane relative to the axis of rotation.

P _eff and R are design parameters that are selected according to the tire's application. Equation 3 suggests that the product of the elastic shear modulus of the shear layer and the radial thickness of the shear layer is approximately equal to the product of the ground contact pressure and the radial position of the outermost range of the second membrane. 13 graphically illustrates their relationship over a wide range of contact pressures and can be used to evaluate shear layer properties for a variety of other applications.

With respect to FIG. 5, the web spokes 150 have a length N in the radial direction, an axial width W approximately corresponding to the axial width of the annular band 110, and a thickness perpendicular to other dimensions. Substantially a sheet-like member. The thickness is much smaller than either the length N or the width W, preferably about 1% to 5% of the radius R of the tire, so that the web spokes are buckled under pressure as shown in FIG. do. Thinner web spokes will have substantially no compressive resistance, ie will bend in the contact area without providing a meaningless pressure over the load bearing. As the thickness of the web spokes increases, the web spokes can provide a constant compressive load bearing force in the ground contact area. However, the prevailing load transfer action of the web spokes as a whole becomes tension. The particular web spoke thickness can be selected to meet certain conditions of the vehicle.

Referring now to FIG. 6, the web spokes 150 of the preferred embodiment of the present invention achieve an advantageous result in which the transverse shape is substantially narrower in the middle between the first membrane 130 and the mounting band 160. . Preferred spokes 150 have a full width W and a radial length N. Preferred web spokes have a transverse cut in the band. The width of the spoke at this cut is reduced by the axial insertion depth D from the axial outside of the spoke. The specific spoke transverse shape is a function of several geometric variables and constraints. The process of acquiring a geometry that follows these limitations requires more than one iteration, but it is empirically known that a solution without unnecessary experimentation is possible.

The cut can extend to the entire radial height N of the spoke. For convenience of design and production, it is advantageous to provide a small area with a basically constant width adjacent to the radially outer and radially inner ranges of the spokes 150. This area is defined by the radial offset distance Q at which the spoke height N is 10% or less. In the example of FIG. 6, the offset distances are the same in the radially outer and radially inner ranges of the spokes 150. However, this is for convenience only and the offset Q may be different for the top and bottom of the spokes. Thus, the radial height of the cutout of the spoke 150 is reduced by a small amount and has a height HC defined equal to the value of the spoke minus the sum of the top and bottom of the offset Q. For the example of FIG. 6, the top and bottom of the offset are the same and hence HC = N-2Q.

The minimum axial depth D of the feature should be at least 5% of the height N and not more than 30% of the spoke width W. The empirical equation for a good value for the maximum axial depth D of the feature is a function of spoke height N and offset Q as follows.

This ensures that the expected depth is less than 30% of the spoke width W, and recognizes that the offset Q is zero.

The particular shape of the feature is not limited and can be formed by a portion of a circular arc, a paraboilc arc, or a combination of straight line segments connected by a bending radius. The final form is the variant shown in Figure 6, which is symmetrical about the center height of the spokes. Each of the straight segments forms an angle alpha that is tangent to the feature and a horizontal line at the radial level of the offset distance Q. The straight segments are connected to a coupling radius RR with a minimum value of at least 20% of the height N of the spokes. Restriction of the bonding radius is necessary to avoid the shape of the cutout where the selected depth D and the tangential angle alpha will result in straight line segments converging to one apex and thus may adversely affect spoke performance.

The transverse shape is determined by first calculating the angle alpha and then determining the coupling radius RR connecting the two segments. It is known that the angle alpha is well specified from the spoke shape as follows.

However, the minimum value of alpha should be at least 10 °.

Once alpha is determined, a good value of the bond radius RR can be calculated from the following equation.

In the case where the selected value of depth D and the calculated value of alpha expect a value of the combined radius RR less than the minimum acceptable value, the process will be repeated for incrementally smaller alpha values until an acceptable RR value is obtained. If no solution is possible for alpha values greater than the minimum of 10 °, the depth D can also be reduced and the process repeated.

As an alternative form of cut, we propose a parabola as shown on the left in FIG. In this example, the parabola passes through the points marked AA, BB and CC, and the tangent angle alpha at points AA and CC is defined as before. Point BB defines a good value of the depth D as shown in Equation 7 as before.

Once the parabola is determined from the cut parameters: height HC, tangential angle alpha and depth D, the coupling radius RR is defined. Since the parabola cannot converge to one vertex, it is believed that the resulting value of the bonding radius RR should be large enough to ensure the correct performance of the web spokes 150.

According to the presently preferred embodiment, the web spokes 150 are formed of a material having a high tensile modulus of about 10 to 100 MPa. Web spokes may be reinforced if desired. The web spoke material will also exhibit an elastic behavior that returns to its original length after being deformed to 30%, and will exhibit a constant stress when the web spoke material deforms to 4%. In addition, it is desirable to have a material having tan Δ not exceeding 0.1 at suitable operating conditions. For example, it is possible to identify commercially available rubber or polyurethane materials that meet the conditions. The inventors have found that Vibrathane B836 ™ urethane, available from the Uniroyal Chemical division of Crompton Corporation, Middlebury, Connecticut, is suitable for web spokes.

With respect to FIG. 2, in one embodiment, the web spokes 150 are interconnected by a radially inner mounting band 160, which surrounds the wheel or hub 10 to install the tire. An interface band 170 interconnects web spokes 150 at their radially outer ends. The interface band 170 connects the web spokes 150 to the annular band 110. For convenience, web spokes, mounting band 160 and interface band 170 may be molded from a single material as a single unit.

Alternatively, depending on the construction material and process for the annular band 110 and hub or wheel 10, the separate mounting band 160 or interface band 170 may be removed and the web spokes may be annular band and wheel. It may be molded or formed to attach directly to it. For example, if either the annular band or wheel or hub is formed of the same or compatible material, the tire can be produced by integrating or forming a web spoke with the annular band or wheel, in which case Mounting band 160 and / or interface band 170 are integrally formed as part of a wheel or annular band. In addition, the web spokes 150 may be mechanically attached to the wheel, for example, by providing an enlargement on the inner end of each web spoke that engages the slot in the wheel.

The manner in which the tire of the present invention supports the applied load can be understood by referring to FIGS. 1 to 6. Region A of the annular band, ie the non-ground contact, acts like an arc and the web spokes 150 are under tension T. The load L on the tire that is transmitted from the vehicle (not shown) to the hub or wheel 10 is basically taken from the arc of area A. The web spokes of transition region B and contact region C are not tensioned. According to a preferred embodiment, the web spokes are relatively thin and provide no more than meaningless vertical load bearing forces. Of course, as the tire rotates, certain parts of the annular band acting as arcs change continuously, but the concept of arc becomes useful for understanding the mechanism.

Substantially pure tensile load support is obtained by having web spokes having high tensile strength but low compressive strength. To facilitate buckling in the ground contact area, the web spokes can be curved. Alternatively, the web spokes can be molded to have curvature and straightened by thermal shrinkage during cooling to provide a substrate to be buckled.

When torque is applied to the wheel, the web spokes 150 must resist torsion between the annular band 110 and the wheel 10. In addition, the web spokes 150 must deflect laterally deflection during rotation or cornering. As will be appreciated, the web spokes 150 present in the radial-axial plane, ie in the plane aligned with respect to both the radial and axial directions, will have a high resistance to the axial force, but in particular the radius Direction, the torque in the circumferential direction will be difficult to resist. For certain vehicles and applications, for example those that produce relatively low acceleration forces, web spoke packages with relatively short spokes that are radially aligned would be suitable.

In applications where high torque is expected, one of the arrangements as shown in FIGS. 7-9 will be more suitable. In FIG. 7, the web spokes 150 are oriented in a repeated X pattern as can be seen in the axial direction, and the pairs of spokes form a combined X character at their center. In FIG. 8, the web spokes are oriented in a zigzag pattern with respect to the radial direction. In FIG. 9, the web spokes are oriented with the adjacent web spokes oriented opposite to the axial direction in a zigzag pattern. In these variants, the orientations provide a force resistive element both in the radial and circumferential directions, thereby maintaining the radial and lateral force resistive elements while increasing the resistance to torque. The angle of orientation can be selected depending on the number of web spokes used and the space between adjacent web spokes.

Other alternative arrangements may be used. As shown in FIG. 10, the web spokes can be arranged in a chevron or V-pattern when viewed in the radial direction. Another alternative is to alternately arrange the orientation of adjacent web spokes between the axially aligned spokes 150 and the circumferentially aligned spokes 15, as shown in FIG. 11. However, this alternative is not good because of the difficulty of accepting bending of web spokes in the contact area.

Due to the various arrangements of the web spokes the vertical, lateral and torsional strength of the tire can be tuned independently of the contact pressure and with respect to each other.

Vertical strength relates to the tire's ability to resist deflection under load. The vertical strength of a tire is strongly influenced by the reaction to the load on the part of the tire that is not in contact with the ground, ie the "counterdeflection" of the tire. 12 illustrates this phenomenon in an exaggerated proportion. When the tire is subjected to a load L, the tire is deflected by the amount of f, and the portion in contact with the ground is the same as the shape of the ground to form the ground contact area C. For the purposes of this description, the reference frame in FIG. 12 keeps the axis X of the tire at a constant position and moves the ground upwards towards the axis. The tire is an elastic body, so the vertical deflection f is proportional to the load L from which the vertical strength K _V of the tire is extracted. The annular band 110 (shown schematically) limited by membranes (not shown) attempts to maintain a certain length to preserve the membrane length, and portions of the tire that do not contact the ground are indicated by dashed lines in the figures. Likewise, they are lifted or deflected away from contact area C. Or the amount λ of reverse deflection is proportional to the load L, and thus the reverse deflection strength K _λ can be obtained. The reverse deflection strength K _λ mainly relates to the way in which the circumferential compressive strength and the web spokes which are not in contact with the ground support the load. For smaller ranges, the transverse and longitudinal bending of the annular band is involved.

Reverse deflection is measured directly by applying a load F to the tire with the shaft fixed and measuring the deflection f of the tire in the contact area and the deflection of the tread surface in the opposite contact area. The reverse deflection strength is then determined by dividing the load F by the reverse deflection amount λ.

In practice, the reverse deflection strength K _λ controls the vertical strength of the tyre, thus substantially controlling the deflection under load against the wheel axis of the tyre. The reverse deflection strength K _λ determines the length of the contact area as shown in FIG. 12. The low reverse deflection strength allows the annular band 110 to move vertically under load, thus reducing the load capacity at this deflection. Thus, tires with high reverse deflection strength have relatively less reverse deflection and longer contact area.

14 graphically shows the approximate relationship between the reverse deflection strength K _λ and the vertical strength of the tire. Figure 14 illustrates the independence of vertical strength and contact pressure useful in the present invention, thereby enabling design flexibility that is not useful in pneumatic tires. Deflated pneumatic tires typically have a reverse deflection strength per unit contact area width of 0.1 DaN / mm ² . In contrast, the tire according to the invention can be designed to have a reverse deflection strength per unit contact area width in the range of at least 0.1 DaN / mm ² .

Advantageously, the starting design parameters for any proposed application can be selected using FIG. 14 in combination with FIG. 13. Once the contact pressure, vertical load and contact area are selected using FIG. 13, the vertical strength characteristics for the tire can be determined using FIG. 14. With the desired approximation to the reverse deflection intensity K _λ obtained from FIG. 13, the designer will then use finite element analysis, which is a useful analytical tool for specifying the structure that achieves this intensity. In addition, design variables will be identified as a task involving the manufacture and testing of tires.

For example, to design a tire of a vehicle intended for a passenger car, the designer can select a design contact pressure P _eff of 1.5 to 2.5 DaN / cm ² , and choose a tire size whose radius R is about 335 mm. By multiplying these values, a "shear layer factor" of 50.25 to 83.75 DaN / cm can be determined, which can be used to specify the shear layer material thickness and shear modulus. In this case, the shear modulus falls within the range of about 3 MPa to about 10 MPa, so that the thickness h of the shear layer is at least 5 mm, preferably about 10 mm to about 20 mm.

Furthermore, according to the invention, the ground contact pressure and the strength of the tires are independent of each other, and in the case of pneumatic tires, all of them are related to the inflation pressure. Thus, the tire can be designed to have a high contact pressure P but a low strength. This may be advantageous when producing tires that have low mass and rolling resistance but retain load bearing capacity.

The reverse deflection strength K _λ can be modified in several ways. Some of the design variables used to adjust this strength include web spoke coefficient, web spoke length, web spoke curvature, web thickness, compression coefficient of annular band membrane, shear layer thickness, tire diameter and width of annular band. .

Vertical strength can be adjusted to optimize the load bearing capacity of a given tire. Alternatively, the vertical strength can be adjusted to provide an annular band of reduced thickness for reduced contact pressure or tire mass while maintaining the desired level of vertical strength.

The vertical strength of the tire of the present invention is also affected by the effect of centripetal forces on the annular band and the sidewalls. As the tire rotation speed increases, centripetal force is generated. In conventional radial tires, centripetal force can increase the operating temperature of the tire. In contrast, the tire of the present invention obtains unexpectedly beneficial results from this same force. When the tire of the present invention rotates under a load, the centripetal force causes the annular band to expand circumferentially and induce additional tension in the web spokes. Web spokes with strength in the radial direction over the range of tires that do not contact (region “A” in FIG. 1) resist this centripetal force. This creates a net upward resultant force that acts to increase the effective vertical strength of the tire and to reduce the radial deflection of the tire to static and non-rotating conditions. This result is obtained to a significant extent when the ratio of the longitudinal strength (2 · E ′ _membrane ) of the band on the tire equator to the effective strength of the web spoke under tension is 100: 1 or less.

Many other variations will be apparent to those skilled in the art upon reading this specification. These and other variations are intended to be within the spirit and scope of the invention as defined by the appended claims below.

The tire according to the present invention provides a non-pneumatic tire having a load absorbing capability or durability possessed by a pneumatic tire while having the shock absorbing capability of conventional pneumatic tires.

Claims (23)

An outer annular band, a plurality of web spokes extending transversely and radially inward from the outer annular band, and means for interconnecting the wheel with the plurality of web spokes; The annular band further comprises a shear layer, at least a first film attached to a radially inner range of the shear layer, and at least a second film attached to a radially outer range of the shear layer, each film comprising a shear layer In a structural support tire having a longitudinal tensile modulus greater than its shear modulus, the spokes have a maximum width and a radial height, A plurality of the web spokes have a cut in the transverse direction to the band, the cut, A height and a shape having a maximum depth greater than 5% of the radial height and less than 30% of the maximum width, The shape has a tangential angle alpha formed by a tangent to the shape and a horizontal line in the radially outermost range and the radially innermost range of the shape, The angle alpha is at least 10 °, And wherein the minimum radius of curvature of the shape is at least 20% of the radial height. The method of claim 1, Wherein the cut is radially offset from the outer annular band and from the means for interconnecting the wheel with the plurality of web spokes, the radial offset being less than or equal to 10% of the height. The method of claim 2, The maximum depth D is

Structural support tire, wherein N is equal to the height and Q is equal to the radial offset. The method of claim 1, The tangential angle alpha is greater than 10 °,

Less than or equal to, wherein HC is equal to the radial height of the cut and D is equal to the depth. The method of claim 1, The radius is greater than 20% of the radial height,

Less than or equal to, wherein HC is equal to the radial height of the cut, D is equal to the depth, and alpha is equal to the tangential angle. The method of claim 1, A structural support tire further comprising a tread portion disposed in the radially outer range of the annular band. The method of claim 1, The means for interconnecting the wheel with the plurality of web spokes comprises a mounting band for interconnecting the radially inner ends of the web spokes. The method of claim 1, The plurality of web spokes further comprise a radial outer band interconnecting the radially outer ends of the web spokes. The method of claim 1, Each web spoke is oriented parallel to the axial direction. The method of claim 1, Wherein the ratio of the longitudinal tensile modulus of one of the membranes to the shear modulus of the shear layer is at least 100: 1. The method of claim 1, The structural support tire, wherein the product of the shear modulus of the shear layer and the radial thickness of the shear layer is equal to the product of the tire ground contact pressure and the radial position of the outermost range of the second membrane. The method of claim 1, Wherein each of the at least one first and second membranes comprises layers of essentially inextensible cord reinforcements embedded in an elastomeric coating layer having a shear modulus of at least equal to the shear modulus of the shear layer. The method of claim 1, wherein the cutting portion is defined by a parabola having a tangent angle alpha that is at least 10 degrees in the radially outermost range and the radially innermost range of the shape, the parabola being an axis corresponding to the maximum depth. Structural support tires that pass through the directional position. In the method of determining the transverse shape of the web spokes, (a) specifying the width and height of the web spokes, the radial offset and the transverse depth of the cut of the shape, ie the transverse depth greater than 5% of the radial height and less than 30% of the width; ; (b) determining a calculated value of the tangential angle defined by the tangent and horizontal lines for the shape; (c) comparing the calculated value of the tangential angle alpha with a predetermined minimum value and setting the tangential angle to the greater of the calculated value or the minimum value; (d) determining a calculated value of the minimum radius of curvature of the transverse shape; (e) comparing the calculated value of the radius with a predetermined minimum value; (f) setting the radius to the larger calculated value if the calculated value is greater than the minimum value. 15. The method of claim 14, wherein the calculated value of the tangential angle alpha is

, Wherein HC is equal to the radial height of the cut and D is equal to the depth. 15. The method of claim 14, wherein the minimum radius is equal to 20% of the radial height N of the web spokes. The method of claim 14, The radius is at least 20% of the radial height,

Less than or equal to, wherein HC is equal to the radial height of the cut, D is equal to the depth, and alpha is equal to the tangential angle. The method of claim 14, The minimum value of the tangential angle is 10 °. The method of claim 14, If the radius is less than the minimum value, further comprising reducing the value of the tangential angle alpha and repeating steps (c) to (f). delete delete delete delete

Images