JPS621B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to wheels for road vehicles. The load carrying capacity of a pneumatic tire is primarily a function of the tread width and the pressure inside the tire. The diameter of the tire is also a factor since it affects the area of the tread surface in contact with the road surface, but the diameter is less important than the width of the tread. Furthermore, in practice, the diameter of a tire is limited by the size of the vehicle on which it is used. For a given load, tires can be selected whose width and pressure are within a certain range. As the width of the tire increases, more material is required and the cost of the tire and the rim on which it is mounted increases. For economic reasons it is desirable to use narrower tires and higher pressures. However, the "ride quality" of the tire must also be considered. This "comfortable ride" is a subjective measure of the performance of a vehicle, and therefore the conclusion as to what "comfortable ride" is varies to some extent from person to person. This ride quality is influenced by both tire construction and operating pressure. A satisfactory objective measure has not yet been established. However, generally maximum pressures of the order of 1.41 to 2.11 Kg/cm ² are used for open carcass tires installed on passenger cars. Higher pressures result in poorer ride quality and discomfort. It is selected to support the expected loads within this pressure range and within the desired tire diameter. Patent No. 1008465 corresponding to U.S. Patent No. 3606921
The pneumatic tube tires disclosed in the specifications of No. 50-17751 and Japanese Patent Application No. 17751, inter alia,
It has the ability to provide a soft and comfortable ride with little noticeable difference in quality over a pressure range of 1.41 to 3.52 or as much as 4.22 Kg/cm ² . The tube tire selected for a given load is much smaller than a beaded open carcass tire subjected to the same load, resulting in reduced material costs and weight savings. The tube tire includes a toroidal elastomeric carcass having an outer tread wall, an inner rim wall, and a pair of side walls interconnecting the tread and rim walls. The carcass is reinforced with continuous inextensible filaments wound in a generally radial plane. The tread belt has non-extensible reinforcements that are generally parallel to the plane of the tire. Due in part to the construction of the sidewalls with uniform radial reinforcing elements that symmetrically increases the sidewall deflection that occurs in the rim and tread as the loads acting on the tire vary, It is the principle of the invention that independence of comfort properties is achieved. This tire has a higher torsional spring rate than comparable tires with open carcass construction, which also contributes to a good ride quality. In contrast to the subjective nature of tire ride comfort, tire characteristics that contribute to vehicle directional control and dynamic stability during direction changes have been objectively analyzed. General Motor Co. has unveiled its Tire Performance Criteria (TPC), which includes force and moment characteristics that measure the directional control ability of the vehicle in which the tire is used. There is. This standard is described in a publication entitled ``General Motor Tire Performance Criteria (TPC) Specification System.'' The force and moment characteristics are from page 74.
This is revealed by page 77. The main tire characteristic that affects linear directional control performance of a vehicle is the cornering coefficient, defined as the lateral force generated by a 1 degree slip angle and 100% rated load divided by the rated load. It is. Early tires made in accordance with the aforementioned US patents were typically 162.56 cm or 223.52 cm in diameter and were used on road grading vehicles. Performance standards for automobile tires are less important for the vehicles mentioned above. Tires of the same construction but reduced in size to a diameter of 68.58 cm for automotive use have a good ride and long life, which is important in the design and operation of passenger vehicles. It has been discovered that there is a defect in certain directional control elements. Its cornering coefficient is too low for road passenger cars to be used satisfactorily. The present invention satisfies or exceeds the performance standards of a general motor tire without adversely affecting the desirable characteristics of the tires of the aforementioned patents, including low rolling resistance, long life and a soft ride at high packing pressures. The invention relates to improvements in the tires disclosed in the above-mentioned US patent specification to obtain force and moment characteristics superior to those of the US Patent. In short, when changing direction during rolling,
Lateral or lateral forces that provide cornering coefficients are generated within the portion of the tire tread that engages the road surface (the "footprint" of the tire) and pass from said tread through said sidewall to engage the tire's rim. to the wheels and the vehicle, thus being effective in changing the direction of motion of the vehicle. The main object of the invention is to stiffen the tread of the tire with respect to lateral forces and to effectively transmit the lateral forces occurring in the tread to the rim of the wheel. One feature of the invention is that the tread wall of the tire is stiffened laterally by a device such as a pair of complementary bias reinforcing strips having significant lateral or stiffness. be. Another feature is the inclusion of a device for securing the rim wall of the tire to the mating rim surface so as to prevent relative lateral movement therebetween. More specifically, for tires with anti-roll hoops in the rim wall, the rim wall and the mating rim surface are such that they prevent lateral inward movement of the hoop relative to the surface of the wheel rim. , having radially extending, interengaging peripheral surfaces between the roll restraining hoops. A further feature is that the tire includes an annular body between the side edges of the tread wall and the rim wall and the side wall, which facilitates the transmission of forces through the tire during rolling changes of direction. be. Further features and advantages will become readily apparent from the following description of the accompanying drawings. A brief discussion of prior art tube tires is provided to highlight the problem solved by the present invention.
FIG. 1 shows a partially cutaway perspective view of a tire from the attached drawing in FIG. 5 of the specification of Japanese Patent No. 1008465. An elastomeric carcass 20 has a tread wall 21, a rim wall 22 and side walls 23,24. The carcass is reinforced by filaments 25 wound in a single layer such that the turns lie substantially in a radial plane. A single circumferential tread 27 surrounds the carcass and is provided with reinforcing elements 28, said reinforcing elements 28 being approximately parallel to the plane of the tire so that the tire is effectively non-stretchable around the periphery. arranged in a plane. For example, reinforcement element 2
5 and 28 may be steel wires. rim wall 2
2 has at its outer edges a pair of anti-roll hoops 29, 30, preferably made of wrapped steel wire. The rim wall 22 has a centrally located radial rib 31 that fits into a recess 32 located centrally between the rim parts 33 and 34. Further details of the construction of this tire and its manufacture are described in the specification of the aforementioned patent no. 1008465. The tire shown in Figure 1 has a soft ride characteristic over a wide range of packed air pressure, and
It has many desirable features including long life and low rolling resistance which contributes to low fuel consumption. However, this prior art tire has drawbacks which adversely affect the suitability of the tire for road vehicles such as cars or trucks. A consideration of the tire force and moment diagram shown in FIG. 2 will assist in the following discussion.
This diagram is adapted from conventions recommended by the Society of Automotive Engineers. tires and wheels 3
8 is shown on the plane 39 of the road. wheel 40
The longitudinal plane of coincides with the arrow 41, which is the direction of the wheel, ie the front direction. The direction of motion of the wheel, indicated by arrow 42, is angularly displaced from said wheel orientation by a slip angle α. The angular misalignment of the wheel orientation and the direction of motion of the wheel results in a lateral force, indicated by arrow 44, in a plane 45 passing through the center of the wheel and perpendicular to the plane 40 of the wheel. become. For the positive slip angle shown, the direction of the lateral force will be in the negative direction. The load applied to the wheel is a vertical force and is represented by arrow 46. Indicated by arrow 47,
The linear torque tends to rotate the wheels so that the orientation of the wheels coincides with the direction of motion of the wheels. In a moving vehicle, it is lateral forces that change the direction of the vehicle when turning the steering wheel.
It is 4. The relationship between the wheel load and slip angle and the lateral force influences the handling characteristics of the vehicle. If the lateral forces are too large, the vehicle will react violently and be difficult to control. If the lateral forces are small, the vehicle will be less responsive. The structure of the tire and the interconnection between the tire and the wheel are the primary factors in generating the lateral forces 44. When changing direction, forces are generated by the interaction between the tire tread and the road surface. The dynamic explanation for the generation of forces in the tread is complex. A simplified qualitative discussion is sufficient for explaining the invention. Part 3a relates to tires in which the peripheral part of the tire that engages the road surface, sometimes referred to as the tire footprint, runs in the direction of the front of the tire.
Schematically illustrated in fig. foot print 5
The longitudinal axis 51 of 0 is a straight line. If the front orientation of the wheel and the direction of motion are different, the footprint will be deformed as shown at 52 and 53 in FIGS. 3b and 3c, respectively. The magnitude of the deformation, which can be measured by the angle β between the two segments of the longitudinal axes 54, 55, is determined primarily by the slip angle α and the resistance of the tread to lateral deformation. If the lateral stiffness of the tread is low (FIG. 3b), the footprint deformation is greater than if the tire is stiff (FIG. 3c). General Motors' tire performance standards listed above are based on the cornering coefficient, which is defined as the lateral force generated at a 1° slip angle and rated tire load divided by the rated load. The tire's ability to generate force 44 on the other hand is confirmed. The first tires made according to the specification of patent no. 1008465 (sometimes referred to herein as "automotive tires") sized for use on road-operated passenger vehicles had cornering coefficients insufficient for passenger vehicles. It has been found that the It is believed that this low cornering coefficient results from the fact that the peripheral tread with reinforcing elements 28 parallel to the plane of the tire has little resistance to lateral deformation. During the direction change, the footprint deforms as shown in FIG. 3b. Two major modifications were made to solve this problem. First, the tread was laterally stiffened. In doing so, the deformation of the footprint is reduced, as shown in Figure 3c, resulting in greater lateral forces in the tread. Second, the tire and wheel rim are interconnected in such a way that relative movements are minimized, in order to effectively transmit the lateral forces occurring in the tire tread from the tire to the wheel. The lateral stiffness of the tread portion of the tire is preferably increased by providing in the tread walls one or more layers of material that resist the bending that occurs in the footprint during rolling changes of direction. A construction that has been found to be satisfactory is illustrated in FIGS. 4 and 5. In each of these tires, two radially spaced elastomer strips with reinforcing elements arranged at complementary bias angles to the plane of the tire surround the inextensible periphery. It is located below the reinforcing belt. More specifically, in FIGS. 4 and 5, the tread is stiffened by reinforcing strips 63, 64 located below the belt 65. These reinforcing strips and the tire into which these reinforcing strips are incorporated,
This will be explained in detail below. It is not sufficient that lateral forces occur in the tire tread. This force must be effectively transmitted through the side wall to the rim wall and from this rim wall to the wheel rim. The connection between the tire rim wall and the wheel rim will now be considered. A lateral force applied to the tread wall of a tube tire as described in the specification of said patent is a force that tends to move said tread wall laterally and to move the anti-roll hoop on the outside of the turn inwardly on the wheel rim. increase. (It should be noted that this effect is the opposite of that for tires with open carcass beads, where the tension acting on the outer bead is reduced during the change of direction.) As the hoop moves, the lateral A shear force is created in the rim wall that dissipates some of the force, and this shear force reduces the force available to turn the vehicle. Two measures are shown which have already been found to be sufficient to minimize the dissipation of the forces mentioned above. 4 and 5, a tire rim wall 77 is shown.
the rim surface 76 on which the rim is seated includes an outwardly extending, centrally located radial step 78;
This step in the radial direction serves as the roll restraining hoop 81, 8.
has a lateral dimension that corresponds to the spacing between the inner surfaces 79 and 80 of No. 2. Roll suppression hoops 81 and 82
are axially spaced apart from the connection between each side wall and the rim-engaging wall portion where the tire engages the rim. The side wall has an arcuate cross section in any plane containing the axis of the wheel. In the above configuration, the coupling that engages the rim wall of the tire and the mounting surface of the rim limits relative movement between the tire and rim to effectively transmit force. Rim surface 76 includes expander and mounting member 84
It may be a transversely segmented ring having Tire rim wall 77 has a generally straight inner surface in the unstressed state. By enlarging the annular rim surface 76 in contact with the tire, the rim step 78 causes the tire rim wall to deform outwardly between anti-roll hoops 81 and 82. The dynamic mechanical effects that occur at the connections between the side walls and the tread and rim walls during rolling changes and that transmit lateral forces from the tread walls to the rim walls are complex and not fully understood. It has not been.
The above-mentioned action mainly occurs near the side edge of the reinforcing belt (65 in FIGS. 4 and 5) in the non-stretchable periphery and on the axially outward surface 75 of the roll restraining hoops 81, 82. it is conceivable that. Transmission of forces from the tread wall to the side wall and from the side wall to the rim wall is facilitated by limiting lateral deformation of the side wall in these areas. More particularly, in FIG. 4, the elastomer body of the tire is thickened at the shoulder in the sidewall area adjacent the edge of the tread wall and is thickened at the axially outer surface 75 of the anti-roll hoop and of said sidewall. An elastomeric filler 89 is disposed between the inner surface and the inner surface. The shoulder and filler 89 are formed by an elastomeric toroid that is incorporated into the levered composite tire structure prior to vulcanization. Automotive tires are made in many different sizes for different loads, with diameters and widths that complete the styling of the vehicle. Physical dimensions and other tire characteristics, including tire performance criteria, are related to tire size. 4th tire size HR78-15 with open carcass bead
Some of the dimensions and component characteristics of the tube tire of FIG. 5 will be given below as an illustration of the invention. It will be appreciated that various combinations of materials and dimensions may be used to construct other types of tires and other sizes of tires. HR78−15 at maximum pressure which is 2.25Kg/ ^cm2
is rated for a load of 803.6Kg. General Motors tire performance standards for this tire are
The nominal cornering coefficient is set at 0.160. Other tires detailed by General Motor have nominal cornering coefficients of 0.150 to 0.195. The HR78−15 mounted on a 15.24 cm (6 inch) rim has a cross-sectional width of 21.46 cm.
It has a bead to tread height of 16.76cm. A lightweight tire is illustrated in FIGS. 4 and 5. Again, the cross-sectional width is 20.32 cm, but the tire has a sidewall thickness of 0.58 cm.
The radius of the outer sidewall surface is 6.6 cm. The width of the tread is 13cm. The radial sidewall reinforcement 96 is
3 x 0.25 mm steel cable at a density of 7 filaments per inch. The lateral reinforcement sheets 63, 64 are 11.68 cm and 12.45 cm wide, respectively, and each has 4 x 4 x 0.0178 mm steel cable reinforcement at a density of 14 filaments per 25.4 mm. The width of the non-stretchable belt 65 is
10.16 cm and reinforced with 5 x 0.025 mm steel cable at a density of 16 filaments per 25.4 mm. Roll suppressing hoops 81 and 82 are 6×5×
Made of 0.094mm steel wire. Rim step 78
has a radial dimension of 0.025 mm and a width of 4.953 mm. Suitable elastomeric compounds for tires are indicated by code numbers in Table A. The main components and physical properties of this elastomeric compound are given in Table B.

【table】

【table】

[Table] The lightweight tires in Figures 4 and 5 have a cornering coefficient of 0.159. The tires of FIGS. 4 and 5 can be operated at pressures significantly higher than 2.11 Kg/cm ² with good ride characteristics. This cornering coefficient increases proportionally to the air packing pressure. This tire can therefore accommodate significantly higher loads than the HR78-15 tire.
On the contrary, smaller tires incorporating the present invention can be selected for use with a load capacity of HR78-15. The weight of this open carcass tire is approximately 14.5Kg
It is. The weight of the comparable lightweight tires of Figures 4 and 5 is 11.4Kg. The almost unlimited selection of elastomeric materials and reinforcement materials available for tire treads allows the production of tires of various sizes with desired cornering coefficients. However, building and testing completed tires is both expensive and time consuming. A sample of the treaded material was tested in a simple beam deflection to ensure that information about the stiffness could be obtained, which correlates predictably with the cornering coefficient of tires using this material in the treaded. This greatly simplifies tread material analysis and tire design. FIG. 6 shows a cross-section of the treaded material prepared for the beam deflection test. Dimensions 1 of sample 116
15 corresponds to the circumferential dimension of the tire tread.
Dimension 117 corresponds to the transverse dimension of the tread. Three holes 118, 119 and 120 are spaced apart from each other along the axis of sample 116 parallel to dimension 115. This specimen has holes 118 and 12.
It is suspended from zero and a deflection force is applied to the hole 119. The deflection of this specimen is a measure of its resistance to lateral deformation. Increased sidewall deflection of a tire is associated with its multipressure and good ride performance. When a load is applied to the tire, the increase in deflection that occurs at the connection between the rim engaging wall and the side wall is the same as the increase in deflection that occurs at the connection between the tread wall and the side wall. The term "multi-pressure" above is used to indicate that one basic tire can have the ability to carry different load ratings simply by changing the operating air pressure within the tire. As a hypothetical example, the lightweight tire shown in Figure 4 has the capacity to carry a load of 770Kg at an air pressure of 2.11Kg/ ^cm2 , and a load of 1359Kg at an air pressure of 4.22Kg/ ^cm2 . may have the ability to carry In both cases, the tire sidewall deflection will be approximately the same and there will be little noticeable difference in ride quality. The above should be contrasted with an open carcass beaded tire where the sidewalls are rigid in the area of the bead and the main deflection occurs at the connection of the sidewall and rim wall. As long as the sidewall of the tire has the above-mentioned ability to increase symmetrical deflection between the tread wall and the rim wall, the advantages of the present invention in establishing multiple pressures, a flexible ride and a desired cornering coefficient. can get. These sidewall characteristics do not require a tube tire construction on a core as described in the corresponding U.S. Pat. This construction is desirable as it provides uniformity and low cost for the tire, but the crown overlap is either buried within the rim wall where deflection forces cannot be applied or within the tread wall where deflection is minimized. If so, similar performance can be achieved using this crown overlap structure. Furthermore, it is not necessary that the sidewall reinforcements lie exactly in the radial plane. Deflections of up to 10° are allowed. A crown-overlap tire is one in which the radially extending reinforcing element of the tire consists of a number of individual elements, one end of which is connected to the other end of the same element. These are tires that overlap. Since this crown overlap tire has the same basic shape as the tire of the invention, it has the same operating characteristics as the tire of the invention as far as sidewall deflection is concerned. To eliminate the effect of bias reinforcement on steering, the tread preferably has two layers of bias reinforcement inside the inextensible 0° belt. The reason is that in the above configuration,
Any lateral force exerted on the tire's footprint by one bias reinforcement layer will be automatically balanced by a similar and opposite lateral force exerted by the other bias reinforcement layer. . However, if the bias layer has sufficient resistance to circumferential expansion to allow only 5% circumferential expansion, the 0° belt may be omitted. There are other tire characteristics that contribute to cornering coefficient, albeit to a lesser extent than lateral tread reinforcement, tire-rim connection, and sidewall filler. The tread width and elasticity of the tread material affect the stiffness of the tread. The wider the tread or the stiffer the material, the greater the cornering coefficient. However, too much heat is generated within the stiff material, which is also detrimental to tire life. The tube tire illustrated in Figures 4 and 5 is disclosed in US Pat. No. 3,776,792 (U.S. Pat.
It can be produced by the method described in the specification of No. 3606921 (division). Patent application 1972--corresponding to U.S. Pat.
It is described in the specification of No. 114262.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a prior art tire with a part cut away, Figure 2 is a diagram of the forces acting on the tire during rolling changes of direction, Figures 3a and 3b.
Figures 3 and 3c are idealized diagrams of the footprint of a series of tires, Figure 4 is a cross-sectional view of another tire embodying the invention, and Figure 5 is Figure 4. FIG. 6 is a schematic diagram of a test useful in comparing materials used to stiffen tire treads. 20... Elastomer carcass, 21... Treaded wall, 22... Rim wall, 23, 24... Side wall,
25... filament, 27... tretz, 28
... Reinforcement element, 29 ... Roll suppression hoop, 30
... Roll suppressing hoop, 31 ... Radial rib, 32 ... Center positioning recess, 41 ... Arrow in the direction of the front of the wheel, 42 ... Arrow in the direction of wheel movement, 44 ... Arrow of lateral force , 45... Plane passing through the center of the wheel, 46... Normal force arrow, 47... Aligning torque arrow, 50... Footprint, 63, 64... Reinforcement strip, 65...
belt.

Claims (1)

Claims: 1. A wheel for a road vehicle having a rim carrying a tire, the tire having a tread wall, the tread wall imparting lateral stiffness to the tread wall and providing resistance during rolling. the tire comprises at least one layer of reinforcing elements for resisting bending of the tread wall that occurs in the footprint of the tread during changes in direction; , a side wall extending from the tread wall to a rim-engaging wall portion that engages the rim, the side wall having a reinforcing element located substantially in a plane containing the axis of the wheel;
and the sidewall has an arc-shaped cross section in any plane including the axis of the wheel, and when the tire is under load, the sidewall forms in the sidewall directly adjacent to the connection between the tread wall and the sidewall. the increase in lateral deflection of is the same as the increase in lateral deflection of the side wall that occurs in the side wall immediately adjacent the connection between the rim-engaging wall portion and the side wall;
Further, each of the rim engaging wall portions is spaced apart from a connecting portion between each side wall and the rim engaging wall portion.
the tire having two hoops, two hoops being arranged on either side of the central circumferential plane of the tire, the hoops being spaced apart and extending radially outwardly between the two hoops; A wheel for a road vehicle, characterized in that, in cooperation with an annular stepped portion of the rim, a radially inward peripheral portion of the tire is restrained from moving axially relative to the rim. 2. A wheel according to claim 1, comprising:
A wheel in which the tread wall has reinforcing elements substantially parallel to a plane perpendicular to the axis of the tire and has a peripheral inextensible belt. 3. A wheel according to claim 2, which
said reinforcing elements disposed on the tread wall to provide lateral stiffness, said breakers having a pair of radially spaced peripherals providing reinforcing elements arranged at a bias angle; A wheel provided by strips, the bias angles of said two strips being equal in magnitude and angularly displaced in opposite directions from the central circumferential plane of said tire. 4. A wheel according to claim 3, which
A wheel wherein said non-stretchable belt is spaced radially outwardly of said breaker strip. 5. A wheel according to claim 4, comprising:
A wheel in which the width of the inextensible belt is less than the width of the breaker strip. 6. A wheel as set forth in claim 5, comprising:
A wheel where the width of the outer breaker strip is less than the width of the inner breaker strip. 7. The wheel of claim 6, wherein the tire has an annular body of elastomer between the side edge of each tread wall and the outer surface of the respective side wall. 8. A wheel according to claim 7, comprising:
A wheel in which the tire has an annular body of elastomer between the outer edge of each hoop and the inner surface of the respective side wall.