Test apparatus and method of measuring surface friction of a brake pad insulator material and method of use of a brake dynamometer

• US 7,398,669 B2
• Filed: 09/28/2005
• Issued: 07/15/2008
• Est. Priority Date: 09/28/2005
• Status: Active Grant

• Current Assignee: Wolverine Advanced Materials LLC (ITT, Inc.)
• Original Assignee: Material Sciences Corporation (New Star Metals Holdings LLC)
• Inventors: Denys, Eric, Mahajan, Sanjay K.
• Primary Examiner(s): Raevis; Robert R
• Application Number:
  US11/236,940
• Publication Number:
  US 20070068220A1
• Time in Patent Office: 1,021 Days
• Field of Search: None
• US Class Current: 73/10
• CPC Class Codes: G01N 19/02 Measuring coefficient of friction between materials testing of tyres G01M17/02; determinations of friction coefficient used in vehicle braking or traction control systems B60T8/172

Abstract

A test apparatus for measuring surface friction of a damping material such as brake pad insulator material includes a rotor configured to support the damping material for rotation therewith, an actuator pressurizable to apply axially-inward force to the damping material and a stator configured to support the actuator. A sensor determines the force applied to the actuator and a torque cell is axially aligned with the rotor for measuring torque of the rotor in relation to force applied to the damping material. The calculation of surface friction of the damping material is possible based on the measured load and torque. A method of measuring surface friction of a brake pad insulator material as well as a method using a brake dynamometer is also presented.

Claims

1. A test apparatus for measuring surface friction of damping material, comprising:

a rotor configured to operatively support the damping material for rotation therewith, the rotor having an outer surface with a recess therein;

at least one actuator operable to apply axially-inward force on the damping material;

a stator configured to operatively support said at least one actuator;

a torque cell operable for measuring torque of the rotor in relation to force applied to the damping material by the actuator, thereby allowing a calculation of surface friction of the damping material; and

a carrier member configured to be supported at least partially within the recess by the rotor for common rotation with the rotor, wherein the carrier member is operable for supporting the damping material.

2. The test apparatus of claim 1, wherein the rotor has a first outer surface and a second outer surface opposing said first outer surface;

wherein the damping material includes a first sample and a second sample;

wherein said at least one actuator includes a first actuator and a second actuator;

wherein said first sample is operatively supported at said first outer surface and said second sample is operatively supported at said second outer surface; and

wherein said first actuator applies an axially-inward force on the first sample and said second actuator applies an opposing axially-inward force on the second sample.

3. The test apparatus of claim 2, wherein said first sample is a first type of material and said second sample is a second type of material.

4. The test apparatus of claim 1, wherein the damping material includes a first sample and a second sample supported at different locations on the rotor.

5. The test apparatus of claim 1, wherein the damping material includes a first sample and a second sample, wherein the recess is a first recess, wherein the carrier member is a first carrier member, wherein the first carrier member operatively supports the first sample, wherein the outer surface has a second recess therein, the second recess being spaced from the first recess, and further comprising:

a second carrier member configured to be supported at least partially within the second recess by the rotor for common rotation with the rotor, wherein the second carrier member operatively supports the second sample.

6. The test apparatus of claim 1, further comprising:

a heater element operatively associated with the damping material for varying the temperature thereof.

7. The test apparatus of claim 6, further comprising:

a temperature sensor operatively connected with the damping material for sensing the temperature thereof.

8. The test apparatus of claim 1, wherein the damping material is brake pad insulator material, and wherein said at least one actuator includes a brake piston and a brake finger coupon.

9. A method of measuring surface friction of a brake pad insulator material comprising:

operatively connecting a brake pad insulator material to a rotor for rotation therewith;

applying an axial force on the brake pad insulator material;

measuring the axial force;

powering the rotor for rotation;

creating a recess in the rotor;

securing a carrier member at least partially within the recess for rotation with the rotor;

connecting the brake pad insulator material to the carrier member; and

measuring torque of the rotor, thereby allowing a calculation of surface friction of the brake pad insulator material based on the measured axial force and torque.

10. The method of claim 9, wherein the brake pad insulator material is characterized by a temperature, and further comprising:

varying the temperature of the brake pad insulator material, thereby permitting correlation of calculated surface friction with temperature.

11. The method of claim 9, wherein the brake pad insulator material is a first sample, and farther comprising:

removing the brake pad insulator material from the carrier member;

connecting a second sample of brake pad insulator to the carrier member; and

repeating the steps of applying an axial force, measuring the axial force, powering the rotor and measuring torque of the rotor, thereby allowing a calculation of surface friction of the second sample of brake pad insulator material.

12. A method of using a brake dynamometer having a controller and a rotatable shaft, comprising:

providing a rotor, a stator, at least one actuator and a damping material;

operatively connecting the rotor with the rotatable shaft for common rotation therewith;

grounding the stator;

operatively connecting said at least one actuator with the stator and with the controller;

operatively connecting the damping material to the rotor;

applying force to the damping material via said at least one actuator;

rotating the rotor while said force is being applied;

measuring torque on the rotor, thereby allowing a calculation of surface friction of the damping material; and

forming a recess in the rotor;

wherein said operatively connecting the damping material to the rotor includes supporting a carrier member at least partially within the recess and connecting the damping material with the carrier member.

13. The method of claim 12, wherein the rotor has a first outer surface and a second outer surface opposing the first outer surface, wherein the damping material includes a first sample and a second sample;

wherein the operatively connecting the damping material to the rotor step includes operatively connecting the first sample at the first outer surface and operatively connecting the second sample at the second outer surface; and

wherein the applying force to the damping material includes applying a force to the first sample and applying a substantially equal, axially opposed force to the second sample such that no net axial force is applied to the rotor.

14. The method of claim 12, further comprising:

controlling the temperature of the damping material via the controller, thereby permitting a correlation of the calculation of surface friction with temperature.