METHOD OF CONTROLLING AND MEASURING TIRE FORCES

• US 3,847,012 A
• Filed: 11/23/1971
• Issued: 11/12/1974
• Est. Priority Date: 03/02/1970
• Status: Expired due to Term

• Current Assignee: Lawrence R. Sperberg
• Original Assignee: Lawrence R. Sperberg
• Inventors: Sperberg, Lawrence R.
• Primary Examiner(s): Woodiel, Donald O.
• Application Number:
  US05/201,587
• Time in Patent Office: 1,085 Days
• Field of Search: 73/146,8,137
• US Class Current: 73/8
• CPC Class Codes: G01L 3/245 by measuring and simultaneously multiplying pressure and velocity
• CPC Class Codes: G01M 17/022 the tyre co-operating with rotatable rolls

Abstract

A method of measuring the energy transmitted between the tread surface of a rotating tire and a moving surface which supports the tire. The power output of the prime mover which rotates the tire may be determined from the measured revolutions per minute (rpm) and manifold pressure (M.P.) or from the fuel flow of an internal combustion engine. This power output is correlated with the actual torque or force exerted by the tire tread surface against a moving surface whereupon the effects of the drivetrain, differential, wheel bearings, and tire flexing losses are eliminated from the observed indicated power output of the engine. The correlation is attained by placing the vehicle upon a force measuring device which has previously been calibrated to measure power expanded upon the device in any suitable power unit, such as horsepower. A dictionary of stored data relating engine performance, such as the observed rpm and manifold pressure, with the actual torque or power exerted by the surface of the tire is provided whereby test data in the form of power output may be subsequently obtained which directly relates the force exerted by the tread surface of the tire to the indicated power delivered by the engine in propelling a vehicle down a highway. This expedient therefore changes the vehicle into a mobile dynamometer, since the dictionary of stored terms can be compared to the indicated engine power output under any operating conditions to enable rapid determination of the actual torque or developed hp which is extended in overcoming the various forces which resist movement of the vehicle.

Claims

1. A method of measuring the work performed by a tire tread surface whicH is held against a moving surface while a portion of the tread compound is abraded away, comprising the steps of:

1. measuring the work performed by the tread surface of the tire as a function of vehicle power plant power output as the power plant causes the tire to rotate against a moving surface which exerts a controlled resisting force against the tire;

2. carrying out step (1) at various rotational velocities of the tire for each of a plurality of controlled resistive forces;

3. recording the vehicle power plant outputs with the work performed against the moving surface at the various velocities and controlled resistive forces to thereby provide a dictionary of stored terms which relates the work performed at the tire tread surface to the vehicle power output;

4. wearing away a portion of the tread surface by rotating the tire by means of said vehicle at a velocity corresponding to one of said various velocities and under a resistive force corresponding to one of said plurality of resistive forces, while recording the power plant output of the vehicle;

5. to thereby determine the work performed by said portion of the tire tread surface during step (4).

2. exerting a plurality of controlled resisting forces into the beads of the tire by connecting the tire to drive a variable torque producing apparatus;

3. recording the vehicle power plant outputs with the work performed against the moving surface at the various velocities and controlled resistive forces to thereby provide a dictionary of stored terms which relates the work performed at the tire tread surface to the vehicle power output;

4. weAring away an outer portion of the tread surface of a tire by rotatably mounting the last said tire with the tread surface thereof placed in rolling contact with a relative moving surface, and rotating the tire at one of said rotational velocities while one of said controlled resisting forces is exerted upon the tire beads;

5. to thereby determine the work performed by said portion of the tire tread surface during step (4).

6. to thereby determine the work performed by said outer portion of the tire tread during step (5).

7. The method of claim 2 wherein the condition of step (5) corresponds to a specific geographical test route negotiated by a vehicle under prescribed conditions.

8. Method of measuring the work required to wear away part of the tire tread of a tire comprising the steps of:

9. The method of claim 8 wherein the moving surface of step (2) is provided by a steel wheel.

10. The method of claim 8 wherein the condition of step (4) corresponds to a specific geographical test route negotiated by a vehicle under prescribed conditions.

11. The method of claim 8 wherein the torque producing means of step (2) is a liquid powered turbine connected to the rotating tire.

12. The method of claim 8 wherein the torque producing means of step (2) is attained through an electric force linkage.