WO2009072902A1 - Apparatus for measuring the friction properties of a surface - Google Patents
Apparatus for measuring the friction properties of a surface Download PDFInfo
- Publication number
- WO2009072902A1 WO2009072902A1 PCT/NO2008/000436 NO2008000436W WO2009072902A1 WO 2009072902 A1 WO2009072902 A1 WO 2009072902A1 NO 2008000436 W NO2008000436 W NO 2008000436W WO 2009072902 A1 WO2009072902 A1 WO 2009072902A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- measuring
- generator
- wheel
- measuring wheel
- friction properties
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N19/00—Investigating materials by mechanical methods
- G01N19/02—Measuring coefficient of friction between materials
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
- B60T8/17—Using electrical or electronic regulation means to control braking
- B60T8/172—Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T2210/00—Detection or estimation of road or environment conditions; Detection or estimation of road shapes
- B60T2210/10—Detection or estimation of road conditions
- B60T2210/12—Friction
Definitions
- the present invention relates to an apparatus for measuring the friction properties of the top layer of a road or airport runway.
- Friction measurements are routinely performed by road and airport authorities, either to incur protective measures if the road/runway becomes too slippery, or for investigating the properties of various surface layers.
- Such measurements are commonly undertaken by trailing a measuring wheel behind a vehicle.
- the wheel is braked achieving a slip of about 18% between the wheel and road.
- This braking action may be achieved with mechanical or hydraulic means.
- the work done by the wheel is measured.
- Both mechanical and hydraulic systems are very temperature sensitive, as the friction of braking bands or the viscosity of hydraulic oil varies with temperature. Hydraulic measuring units in particular are complicated and costly to manufacture and maintain.
- prior art measuring wheels are apt to jump or jolt on uneven road surfaces; which introduces noise in the measurements.
- the apparatus includes a measuring wheel which is rolled along the surface while being pressed against the surface with a predefined force, an electrical generator which is connected to the measuring wheel and driven by said measuring wheel, a load resistor which is connected to said generator and adapted to dissipate electric power generated by the generator, means for measuring the power generated by the generator, and means for determining the surface friction properties from the measured power.
- Fig. 1 is a schematic drawing illustrating the measuring principle used in the invention
- Fig. 2 illustrates the mechanical design of a measuring unit according to the present invention.
- Fig. 1 illustrates schematically how the measurements are performed in an apparatus according to the present invention.
- the measuring setup includes a measuring wheel 1 that is trailed behind a vehicle (not shown) while it is pressed against the road surface with a predefined force Fi oad -
- the heavy arrow indicates the direction of motion.
- the wheel 1 is driving an electrical generator 2 through a belt 3.
- the generator 2 is connected to a load resistor 4, and thus acts to brake the wheel 1.
- the braking force F dra g is controlled by a controller 5.
- the controller 5 controls the electrical power deposited in the load 4 by controlling the magnetization of the generator's rotor.
- the power delivered by the generator is proportional to the revolution rate and the magnetization current.
- the setup also includes means for measuring the voltage across the load resistor 4, and means for computing the friction properties of the surface from these measurements. These means are not shown in the illustration.
- the load resistor 4 is converting the power generated by the generator 2 into heat.
- the load resistor is made of a particular alloy, which is stable with temperature. This means that the load will stay constant even if the power level is varying. This also means that a simplification of the power measurement, as we may measure the voltage u across the load and calculate the power p:
- Fdrag may be computed from the following relationship:
- ⁇ is the degree of efficiency (a constant) and v is the velocity.
- Fig. 2 illustrates the mechanical design of the invention.
- the friction measuring - apparatus has a mechanical construction which aims at reducing errors from an uneven support. Since the friction coefficient is a relationship between F drag and Fi oad , the system is dependent on Fi oad being as stable as possible, without being influenced by accelerations caused by the support.
- the measuring wheel 1 is suspended in a control arm 6.
- the control arm 6 is fastened to a measuring carriage 7 in a hinge point 8.
- a spring damper unit 9 is connected between the arm 6 and the carriage 7 damping the action of the arm.
- the carriage is connected to the vehicle 10 in a free swinging pivot point 11. In this way, the measuring wheel is spring suspended and dampened against the carriage, while the carriage may move freely vertically. If there is a proper ratio between spring suspended and not spring suspended mass, unwanted noise caused by variations in the vertical distance between the wheel and carriage will become attenuated. If the mass of the carriage is at least five times the mass of the measuring wheel, the noise contribution will be about 1/6 compared with a traditional stiff measuring setup.
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- Engineering & Computer Science (AREA)
- Automation & Control Theory (AREA)
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Force Measurement Appropriate To Specific Purposes (AREA)
Abstract
It is disclosed an apparatus for measuring the friction properties of a surface, said apparatus being arranged to be trailed by a vehicle, the apparatus including a measuring wheel (1) which is rolled along the surface while being pressed against the surface with a predefined force (Fload), said apparatus further including an electrical generator (2) which is connected to the measuring wheel (1) and driven by said measuring wheel (1), a load resistor (4) which is connected to said generator (2) and adapted to dissipate electric power generated by the generator (2), means for measuring the power generated by the generator, and means for determining the surface friction properties from the measured power.
Description
APPARATUS FOR MEASURING THE FRICTION PROPERTIES OF A SURFACE
Field of the Invention
The present invention relates to an apparatus for measuring the friction properties of the top layer of a road or airport runway.
Technical Background
Friction measurements are routinely performed by road and airport authorities, either to incur protective measures if the road/runway becomes too slippery, or for investigating the properties of various surface layers.
Such measurements are commonly undertaken by trailing a measuring wheel behind a vehicle. The wheel is braked achieving a slip of about 18% between the wheel and road. This braking action may be achieved with mechanical or hydraulic means. Then, the work done by the wheel is measured. Such systems have several drawbacks. Both mechanical and hydraulic systems are very temperature sensitive, as the friction of braking bands or the viscosity of hydraulic oil varies with temperature. Hydraulic measuring units in particular are complicated and costly to manufacture and maintain. In addition, prior art measuring wheels are apt to jump or jolt on uneven road surfaces; which introduces noise in the measurements.
Summary of the Invention
It is an object of the present invention to provide an improved apparatus for measuring friction, which alleviates at least some of the drawbacks associated with prior art measuring wheels mentioned above.
This is achieved in an apparatus for measuring the friction properties of a surface, as claimed in the appended claim 1. In particular the apparatus includes a measuring wheel which is rolled along the surface while being pressed against the surface with a predefined force, an electrical generator which is connected to the measuring wheel and driven by said measuring wheel, a load resistor which is connected to said generator and adapted to dissipate electric power generated by the generator, means for measuring the power
generated by the generator, and means for determining the surface friction properties from the measured power.
Brief Description of the Drawings
Fig. 1 is a schematic drawing illustrating the measuring principle used in the invention,
Fig. 2 illustrates the mechanical design of a measuring unit according to the present invention.
Detailed Description
The invention will now be described in detail in reference to the above-mentioned drawings.
Fig. 1 illustrates schematically how the measurements are performed in an apparatus according to the present invention. The measuring setup includes a measuring wheel 1 that is trailed behind a vehicle (not shown) while it is pressed against the road surface with a predefined force Fioad- The heavy arrow indicates the direction of motion. The wheel 1 is driving an electrical generator 2 through a belt 3. The generator 2 is connected to a load resistor 4, and thus acts to brake the wheel 1. The braking force Fdrag is controlled by a controller 5. The controller 5 controls the electrical power deposited in the load 4 by controlling the magnetization of the generator's rotor. The power delivered by the generator is proportional to the revolution rate and the magnetization current. The setup also includes means for measuring the voltage across the load resistor 4, and means for computing the friction properties of the surface from these measurements. These means are not shown in the illustration.
The load resistor 4 is converting the power generated by the generator 2 into heat. The load resistor is made of a particular alloy, which is stable with temperature. This means that the load will stay constant even if the power level is varying. This also means that a simplification of the power measurement, as we may measure the voltage u across the load and calculate the power p:
Ii3
(D
where r is the resistance of the load.
Fdrag may be computed from the following relationship:
Fdrag = ■ η * r * v (2)
where η is the degree of efficiency (a constant) and v is the velocity.
Then, the friction coefficient μ is given as:
Fig. 2 illustrates the mechanical design of the invention. The friction measuring - apparatus has a mechanical construction which aims at reducing errors from an uneven support. Since the friction coefficient is a relationship between Fdrag and Fioad, the system is dependent on Fioad being as stable as possible, without being influenced by accelerations caused by the support.
In Fig. 2, the measuring wheel 1 is suspended in a control arm 6. The control arm 6 is fastened to a measuring carriage 7 in a hinge point 8. A spring damper unit 9 is connected between the arm 6 and the carriage 7 damping the action of the arm. The carriage is connected to the vehicle 10 in a free swinging pivot point 11. In this way, the measuring wheel is spring suspended and dampened against the carriage, while the carriage may move freely vertically. If there is a proper ratio between spring suspended and not spring suspended mass, unwanted noise caused by variations in the vertical distance between the wheel and carriage will become attenuated. If the mass of the carriage is at least five times the mass of the measuring wheel, the noise contribution will be about 1/6 compared with a traditional stiff measuring setup.
Claims
1. An apparatus for measuring the friction properties of a surface, said apparatus being arranged to be trailed by a vehicle (10), the apparatus including a measuring wheel (1) which is rolled along the surface while being pressed against the surface with a predefined force (F|oad), c h a r a c t e r i z e d i n an electrical generator (2) which is connected to the measuring wheel (1) and driven by said measuring wheel (1), a load resistor (4) which is connected to said generator (2) and adapted to dissipate electric power generated by the generator (2), means for measuring the power generated by the generator, means for determining the surface friction properties from the measured power.
2. An apparatus as claimed in claim 1, said apparatus including a controller (5) arranged to control the power generated by the generator (2), until a predefined slip is achieved between the measuring wheel (1) and the surface.
3. An apparatus as claimed in claim 2, wherein the controller (5) controls a magnetizing current in said generator (2).
4. An apparatus as claimed in claim 1, said apparatus including a measuring carriage (7) which is connected to the vehicle (10) in a free swinging pivot point (11), wherein the measuring wheel (1) is suspended in a control arm (6) which is connected to the measuring carriage (7) in a hinge point (8), a spring damping unit (9) being connected between the control arm (6) and the measuring carriage (7).
5. An apparatus as claimed in claim 4, wherein the mass of the measuring carriage (7) is at least five times the mass of the measuring wheel (1).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NO20076309 | 2007-12-07 | ||
| NO20076309A NO327696B1 (en) | 2007-12-07 | 2007-12-07 | friction Maler |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2009072902A1 true WO2009072902A1 (en) | 2009-06-11 |
Family
ID=40548783
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/NO2008/000436 WO2009072902A1 (en) | 2007-12-07 | 2008-12-08 | Apparatus for measuring the friction properties of a surface |
Country Status (2)
| Country | Link |
|---|---|
| NO (1) | NO327696B1 (en) |
| WO (1) | WO2009072902A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2967259A1 (en) * | 2010-11-09 | 2012-05-11 | Michelin Soc Tech | TRIBOLOGICAL TEST METHOD RELATING TO A TIRE |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2279409A (en) * | 1939-02-23 | 1942-04-14 | Wagner Electric Corp | Brake testing apparatus |
| US4909073A (en) * | 1988-10-28 | 1990-03-20 | Kabushiki Kaisha Komatsu Seisakusho | Apparatus for measuring a resistance against slippage on road surface |
| US4958512A (en) * | 1988-04-07 | 1990-09-25 | Oddvard Johnsen | Method and a device for use in determining conditions of runway friction and braking |
| WO1996028719A2 (en) * | 1995-03-13 | 1996-09-19 | Hurson James Kevin | Method and apparatus for continuous monitoring of road surface friction |
| US6681614B1 (en) * | 2000-09-06 | 2004-01-27 | Daniel L. Riffe | Apparatus for testing co-efficient of friction of a road surface |
| WO2007106204A2 (en) * | 2006-01-11 | 2007-09-20 | Halliday Donald R | Roadway grip tester and method |
-
2007
- 2007-12-07 NO NO20076309A patent/NO327696B1/en unknown
-
2008
- 2008-12-08 WO PCT/NO2008/000436 patent/WO2009072902A1/en active Application Filing
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2279409A (en) * | 1939-02-23 | 1942-04-14 | Wagner Electric Corp | Brake testing apparatus |
| US4958512A (en) * | 1988-04-07 | 1990-09-25 | Oddvard Johnsen | Method and a device for use in determining conditions of runway friction and braking |
| US4909073A (en) * | 1988-10-28 | 1990-03-20 | Kabushiki Kaisha Komatsu Seisakusho | Apparatus for measuring a resistance against slippage on road surface |
| WO1996028719A2 (en) * | 1995-03-13 | 1996-09-19 | Hurson James Kevin | Method and apparatus for continuous monitoring of road surface friction |
| US6681614B1 (en) * | 2000-09-06 | 2004-01-27 | Daniel L. Riffe | Apparatus for testing co-efficient of friction of a road surface |
| WO2007106204A2 (en) * | 2006-01-11 | 2007-09-20 | Halliday Donald R | Roadway grip tester and method |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2967259A1 (en) * | 2010-11-09 | 2012-05-11 | Michelin Soc Tech | TRIBOLOGICAL TEST METHOD RELATING TO A TIRE |
| WO2012062990A1 (en) * | 2010-11-09 | 2012-05-18 | Societe De Technologie Michelin | Tribological test method relating to a tyre |
Also Published As
| Publication number | Publication date |
|---|---|
| NO327696B1 (en) | 2009-09-14 |
| NO20076309L (en) | 2009-06-08 |
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