Measuring and testing – Frictional resistance – coefficient or characteristics
Patent
1997-05-02
1998-09-29
Raevis, Robert
Measuring and testing
Frictional resistance, coefficient or characteristics
G01N 1902
Patent
active
058147187
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method for measuring or controlling friction relationships by interaction between a pneumatic vehicle rubber tyre and a surface during rolling movement with slip conditions between the wheel and the surface, comprising reel-time calculation of friction relationships by means of friction-slip speed relations during an acceleration or deceleration time interval for the rolling motion of the wheel relative to the surface.
The invention also comprises apparatus or equipment for use in the method for various applications that can utilize the fundamental solutions forming the basis of the invention.
At one hand, there is here the question of measurement, either of a vehicle rubber tyre or of a surface, such as a road or a runway at airports. On the other side, the invention can be utilized in controlling a traction process, i.e. either a braking effect or a propulsion effect for a vehicle,-including both automobiles and airplanes being provided with pneumatic rubber tyres. As far as airplanes is concerned, there will normally only be the question of controlling the braking effect. Control of the type discussed here, as a rule takes place during a rather short time interval, for example from fractions of a second to a few seconds. It is well known that in particular in the case of braking an optimal control of the short interval braking process will be of critical significance in many situations.
Measurement of the friction or traction properties of rubber tyres or wheels is of course also a very important field of use, such as for car tyre producers. On the other hand measurement of friction properties of runway or road surfaces is very significant to road builders, not the least when the road surface or runway has a coating or contamination, including ice or snow, which can influence the friction relationships.
For a long time, research has been made of the very complicated physical relationships and factors being of relevance within the technical field concerned herein, and the development in recent time in such respects can be considered to be represented, inter alia, by Norwegian Patent No. 165.856 and the corresponding U.S. Pat. Nos. 4,958,512 and 5,249,851. Moreover reference is made here to the applicants own publication "An Update on Road Grip Friction", distributed during IX PIARC Winter Road Congress, Seefeld, March 1994. Among other things, the publication contains a long list of references.
In European patent specification EP-287862 there is described applications of indirect and approximate methods for calculating friction between a pneumatic wheel and a road surface, based on measurements of vehicle velocity, rotational speed of the wheel and big changes of slip speed (vehicle velocity minus peripheral speed of the wheel) when the torque of a drive motor and thereby of the drive wheel is continuosly estimated-by-measuring supplied fuel. There is no attempt, however, at determining the friction relationship mathematically for further utilization for the purpose of control. Rather there is employed a trial-and-error method in order to identify the indirect influence of the maximum friction on the rotational speed of the wheel, and control based on the measured manipulated variable parameters for fuel among other things, being present just before the big change of slip speed took place.
This invention provides solutions based on new understanding gained by the inventors, including important mathematical relations for describing friction relationships which previously to a substantial degree have been studied empirically and with graphic methods after comprehensive measurements. Previously known methods in this field have been based on the observation of friction relationships as a function of percentage slip-or sliding between the peripheral surface of the wheel and the pavement. This type of observation in particular forms the basis of the patents referred to above. In contrast, it has been found in connection with the present invention, that it is highly advantageous to l
REFERENCES:
patent: 5281008 (1994-01-01), Kawamura et al.
patent: 5311433 (1994-05-01), Igata et al.
Andresen Arild
Johnsen Oddvard
Rado Zoltan
Norsemeter A/S
Raevis Robert
LandOfFree
Method and apparatus for measuring or controlling friction does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for measuring or controlling friction, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for measuring or controlling friction will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-687179