Measuring and testing – Tire – tread or roadway
Reexamination Certificate
2000-10-24
2003-05-20
Oen, William (Department: 2855)
Measuring and testing
Tire, tread or roadway
Reexamination Certificate
active
06564625
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of designing a tire, a method of designing a vulcanizing mold for a tire, a method of making a vulcanizing mold for a tire, a method of manufacturing a pneumatic tire, and a recording medium with a tire designing program recorded thereon. Specifically, the present invention relates to a tire designing method for designing a tire while considering the performance of a pneumatic tire used in an automobile or the like, particularly the tire performance, such as drainage performance, on-snow performance, and noise performance, in the presence of a fluid, a method of designing a vulcanizing mold for a tire which vulcanizing mold is for manufacturing a tire, a method of making a vulcanizing mold for a tire, a method of manufacturing a pneumatic tire, and a recording medium with a tire designing program recorded thereon.
2. Description of the Related Art
Conventionally, in the development of a pneumatic tire, tire performance is obtained by conducting performance tests by actually designing and manufacturing a tire and mounting it on an automobile, and if the results of the performance tests are unsatisfactory, the procedure is repeated starting from the design and manufacture. In recent years, owing to the development of numerical analysis techniques such as the finite element method and the development of the computer environment, it has become possible to estimate by computers the state of inflation of the tire with internal pressure and the state of load at a time when the tire is not rolling, and it has become possible to make a number of performance estimates based on this estimation. However, it has hitherto been impossible to compute those tire performances such as drainage performance, on-snow performance, and noise performance, that are determined by the behavior of a fluid. For this reason, the present situation is such that it is impossible to conduct the estimation of tire performance and efficiently perform tire development.
A technical document is known in which an attempt was made to analyze the drainage performance, particularly hydroplaning, of a tire with respect to a smooth tire (grooveless tire) and a tire provided with only circumferential grooves (“Tire Science and Technology, TSTCA, Vol. 25, No. 4, October-December, 1997, pp. 265-287”).
However, in this conventional technical document, analysis is attempted with respect to only the smooth tire and the tire provided with only circumferential grooves, and no reference is made to tires with patterns having inclined grooves intersecting the circumferential direction of the tire, which largely contribute to the drainage performance in actual tires. Further, how the fluid during ground contact and rolling of the tire can be brought close to a flowing state and how transient analysis can be made possible is not addressed. Namely, no consideration has been given to an analysis in which an actual tire is assumed to be in an actual environment.
SUMMARY OF THE INVENTION
In view of the above-described facts, an object of the present invention is to obtain a method of designing a tire which is capable of making tire development efficient while considering performance, such as drainage performance, on-snow performance, and noise performance, of a tire actually used in the presence of a fluid, and is capable of obtaining a tire exhibiting satisfactory performance, a method of designing a vulcanizing mold for a tire, a method of making a vulcanizing mold for a tire, a method of manufacturing a pneumatic tire, and a recording medium (recordable/readable medium) with a tire designing program recorded thereon.
To attain the above object, in the present invention, performance, such as drainage performance, on-snow performance, and noise performance, of a tire actually used in the presence of a fluid is estimated. In particular, the fluid at the time of ground contact and rolling of the tire is brought close to a flowing state, and transient analysis is made possible. In addition, the development of the tire is made efficient, and the provision of a tire having satisfactory performance is facilitated.
Specifically, the method of designing a tire according to a first aspect of the invention comprises the steps of: (a) determining a tire model having no pattern configuration to which deformation can be imparted by at least one of ground contact and rolling, and a fluid model at least partially filled with a fluid which comes into contact with at least a portion of the tire model; (b) performing deformation calculation of the tire model based on the at least one of ground contact and rolling of the tire model; (c) performing fluid calculation of the fluid model based on the at least one of ground contact and rolling of the tire model; and (d) estimating behavior of the fluid model due to the at least one of ground contact and rolling of the tire model, and designing a pattern configuration for the tire model based on the behavior of the fluid model.
A second aspect of the invention is the method according to the first aspect, wherein, in the step (d), at least one streamline of the fluid model, as the behavior of the fluid model, is estimated, and at least one groove is formed on the tire model on the basis of a direction in which the streamline extends.
A third aspect of the present invention is the method according to the first aspect, wherein, in the step (d), a pressure distribution of the fluid model, as the behavior of the fluid model, is estimated, and at least one groove is formed on the tire model on the basis of the pressure distribution of the fluid model.
A fourth aspect of the present invention is the method according to the third aspect, wherein, in the step (d), at least one substantially straight groove is formed on the tire model in a circumferential direction thereof on the basis of the pressure distribution of the fluid model.
A fifth aspect of the present invention is the method according to the third aspect, wherein, in the step (d), a volume of the groove formed on the tire model is determined on the basis of the pressure distribution of the fluid model.
A sixth aspect of the present invention is the method according to the first aspect, wherein re-execution of the steps (b), (c) and (d) is done using the tire model having the pattern configuration designed in the step (d), and at least one of a notch and a sipe is formed on the tire model on the basis of the behavior of the fluid model estimated in the re-execution of the steps (b), (c) and (d).
A seventh aspect of the invention is the method according to the first aspect further comprising the steps of: (1) identifying a boundary surface between the tire model after the deformation calculation in the step (b) and the fluid model after the fluid calculation in the step (c); (2) imparting a boundary condition, relating to the identified boundary surface, to the tire model and the fluid model; and (3) performing deformation calculation of the tire model and fluid calculation of the fluid model; wherein the steps of identifying a boundary surface, imparting a boundary condition, and performing deformation calculation of the tire model and fluid calculation of the fluid model are repeated until the fluid model assumes a state of pseudo flow.
An eighth aspect of the invention is the method according to the seventh aspect, further comprising the step of determining a physical quantity present in at least one of the tire model and the fluid model obtained in the steps (1) to (3), wherein in the step (d), the behavior of the fluid model is estimated on the basis of the physical quantity.
A ninth aspect of the invention is the method according to the first aspect, wherein the step (a) further includes determining a road surface model in contact with the fluid model.
A tenth aspect of the invention is the method according to the first aspect, wherein, in the step (b), the deformation calculation is repeated for no more than a predetermined time duration.
An eleventh aspect of
Bridgestone Corporation
Oen William
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