Data processing: measuring – calibrating – or testing – Measurement system – Measured signal processing
Reexamination Certificate
1999-05-27
2001-11-20
Hoff, Marc S. (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system
Measured signal processing
C073S146000
Reexamination Certificate
active
06321180
ABSTRACT:
TECHNICAL FIELD
This invention relates to the method of characterizing the level of noise generated by a tire. More particularly, the present invention relates to a method of using a footprint shape factor (FSF) calculation to characterize the noise generated by a tire tread contacting a road surface.
BACKGROUND ART
A tire manufacturer seeks to design a tire tread which not only fulfills its function relating to wear, wet and dry traction, rolling resistance, and other desirable properties, but which also operates with a acceptably low noise level. Preferably, the tire should run at an acceptable noise level through the entire operating range of a particular vehicle on which the tire is to be mounted. It is therefore necessary to evaluate a tire for noise acceptability. Historically, this has been done by hand cutting a set of tires or building a mold to produce a set of experimental tires for evaluation. These tires are normally loaded and normally inflated and then run against a surface at a predetermined speed during which time the tire noise is measured. This process is expensive and time consuming, thus limiting the number of trials available to the design engineer to optimize the tire design.
A number of methods for predicting the noise level of a specific tire design have been developed for a running tire. For example, U.S. Pat. Nos. 4,788,651 and 5,295,087 relate to methods of simulating noise generated by a tire with a computer. However, none of the conventional noise simulators take into account the effect of the aspect ratio of the tire in analyzing the construction of a tire with regards to the level of noise it generates.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method of characterizing the level of noise generated by a tire having a specific footprint configuration to obviate the problems and limitations of the prior art methods.
It is another object of the present invention to provide a method of characterizing the level of noise generated by a tire through analyzing the shape of the tires footprint and taking into account the aspect ratio of the tire.
Another object of the invention is to provide a method of characterizing the level of noise generated by a tire with a calculation that accounts for the aspect ratio of the tire and then: a) measuring the noise level if the solution to the calculation is inside of a predetermined range; or b) reconfiguring the footprint if the solution to the calculation is outside of a predetermined range.
Accordingly, there is provided a method for characterizing the potential noise level generated by a tire tread during the rotation of a tire in contact with a road surface. The method includes the steps of: a) determining the location of a leading edge of a footprint of the tire tread which first comes into contact with the road surface when the tire rotates with respect to the location of a trailing edge of the footprint that last comes into contact with the road surface when the tire rotates; b) determining the length of the footprint from the leading edge to the trailing edge extending along a centerline disposed halfway between first and second lateral edges of the tire footprint; c) determining the length of the footprint from the leading edge to the trailing edge in proximity to the first and second lateral edges of the footprint at a location corresponding to about 80% of the lateral distance from the centerline to the first and second lateral edges when the aspect ratio is more than about 60; d) determining the length of the footprint from the leading edge to the trailing edge in proximity to the second lateral edge of the footprint at a location corresponding to about 90% of the lateral distance from the centerline to the first and second lateral edges when the aspect ratio is less than about 60; e) calculating the footprint shape factor of the tire having an aspect ratio above about 60 with an equation
FSF80
%
=
L
(
A
1
+
A
2
)
/
2
or
with
an
equation
FSF90
%
=
L
(
B
1
+
B
2
)
/
2
when the aspect ratio of the tire is below about 60; and f) measuring the noise level of the tire when either 0.9<FSF80%<1.6 or 0.9<FSF90%<2.0. In the event that the condition 0.9>FSF80%>1.6 or 0.9>FSF90%>2.0 exists, the footprint is reconfigured and steps a) though f) are rerun.
REFERENCES:
patent: 4788651 (1988-11-01), Parker et al.
patent: 5269357 (1993-12-01), Killian
patent: 5295087 (1994-03-01), Yoshida et al.
patent: 6112167 (2000-08-01), Zakelj
patent: 0329927 (1989-08-01), None
patent: 0480425 (1992-04-01), None
Cohn Howard M.
Hoff Marc S.
Raymond Edward
The Goodyear Tire & Rubber Company
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