WO2004090368A1 - Device for detecting the maximum temperature of use of a brake pad lining - Google Patents

Device for detecting the maximum temperature of use of a brake pad lining Download PDF

Info

Publication number
WO2004090368A1
WO2004090368A1 PCT/IB2004/001085 IB2004001085W WO2004090368A1 WO 2004090368 A1 WO2004090368 A1 WO 2004090368A1 IB 2004001085 W IB2004001085 W IB 2004001085W WO 2004090368 A1 WO2004090368 A1 WO 2004090368A1
Authority
WO
WIPO (PCT)
Prior art keywords
friction member
temperature
subjected
backing plate
sensitive material
Prior art date
Application number
PCT/IB2004/001085
Other languages
French (fr)
Inventor
Otto Carl Muller
Original Assignee
The Warthog Trust
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by The Warthog Trust filed Critical The Warthog Trust
Publication of WO2004090368A1 publication Critical patent/WO2004090368A1/en

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D66/00—Arrangements for monitoring working conditions, e.g. wear, temperature
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D66/00—Arrangements for monitoring working conditions, e.g. wear, temperature
    • F16D2066/001—Temperature

Definitions

  • This invention relates to a brake pad.
  • a brake pad consists of a metal backing plate to which a friction lining is secured.
  • the life of the friction lining inter alia is dependent on the temperature the lining is subjected to during braking. Hard or excessive braking subjects the friction lining to higher temperatures than normal braking thereby reducing the life of the friction lining.
  • a brake pad is often sold with a warranty that it can be used for a minimum number of kilometres.
  • a warranty claim is submitted to a brake pad manufacturer for the friction lining having prematurely worn out, the manufacturer cannot tell if the brake pad was abused by hard or excessive braking which is generally not covered by the warranty.
  • thermocouple is attached to a brake shoe and to a temperature gauge.
  • the temperature of the brake shoe can be monitored by a driver of a vehicle to provide a warning to the driver in the event of overheating of the brake shoe. It will be appreciated that such a brake condition indicator will not assist a brake pad manufacturer in determining whether or not the brake pad was subjected to excessive temperatures when faced with a warranty claim.
  • a friction member having a backing plate and a friction lining includes a temperature indicator in the form of a temperature sensitive material which will change its colour when subjected to a temperature above a specific level so that a subsequent inspection of the temperature indicator will indicate whether or not the friction member was subjected to a temperature above a specific level.
  • Two or more temperature indicators may be provided with a first temperature indicator undergoing a colour change at a lower temperature than a second temperature indicator and so on.
  • the temperature indicators discolour successively at increasing temperature thresholds.
  • three temperature indicators may be provided, the first of which will change its colour at 150°C, the second of which will change its colour at 250°C, and the third of which will change its colour at 350°C.
  • Each temperature indicator is preferably a different colour before it undergoes a colour change.
  • the temperature indicators may be green, orange and red, with the green one turning black at 150°C, the orange one turning black at 250°C, and the red one turning black at 350°C.
  • the temperature sensitive material may be a heat sensitive paint or a sticker.
  • the paint may be located within blind holes or grooves in the backing plate. Thus the paint may be provided in dots or lines.
  • the holes or grooves may be located side-by-side and may be provided on the rear or the side of the backing plate.
  • the holes or grooves may be less than one millimetre deep, and preferably about 0,5 millimetre deep. It will however be appreciated that the paint could be located on a suitable part of the friction member and that the holes or grooves could be any suitable depth.
  • the friction member may be a brake pad, brake shoe or a clutch plate.
  • a method of applying a temperature indicator to a friction member having a backing plate and a friction lining includes the steps of forming a recess in the backing plate and locating a temperature sensitive material within the recess, which temperature sensitive material will change its colour when subjected to a temperature above a specific level.
  • the recess may be a blind hole or a groove.
  • a method of determining the level of abuse to which a friction member was subjected includes the steps of:
  • the method may include the step of linking the determination of the level of abuse to which the friction member was subjected to an assessment of a warranty claim for the friction member by reducing the warranty claim according to the level of abuse to which the friction member was subjected.
  • Figure 1 is a perspective view of a brake pad according to the invention.
  • Figure 2 is a cross-section side view on line II - II of figure 1 ;
  • Figure 3 is a perspective view of a brake pad according to another embodiment of the invention.
  • a brake pad 10 has a steel backing plate 12 with a front surface 14 to which a friction lining 16 is secured.
  • a rear surface 18 of the backing plate 12 has three spaced blind holes 20.1 to 20.3 about 0,5 mm deep.
  • the holes contain dots of irreversible temperature sensitive paint 22.1 to 22.3.
  • the dot of paint 22.1 is green and will discolour (turn black) at a temperature of about 150°C.
  • the dot of paint 22.2 is orange and will discolour at a temperature of about 250°C.
  • the dot of paint 22.3 is red and will discolour at a temperature of about 350°C. This temperature range corresponds with the type of braking the brake pad 10 is likely to be subjected to.
  • the manufacturer can determine to what extent, if any, the brake pad was abused. In this regard if none of the dots of paint 22.1 to 22.3 has discoloured then a customer would be entitled to a full warranty claim (100 000 kms). If only the green paint dot 22.1 has discoloured, then the customer would be entitled to 35% of the warranty claim (35 000 kms). If both the green and orange paint dots 22.1 and 22.2 have discoloured, the customer would be entitled to 20% of the warranty claim (20 000 kms). If all three of the paint dots 22.1 to 22.3 have discoloured then the customer would not be entitled to any warranty claim.
  • a brake pad 30 has a steel backing plate 32 with a friction lining 34.
  • Four blind holes 36.1 to 36.4 are spaced from one another on the backing plate 32.
  • Each of the holes 36.1 to 36.4 has a different coloured dot of temperature sensitive paint 38.1 to 38.4.
  • the first dot of paint 38.1 is white and discolours by turning light grey at about 150 °C.
  • the second dot of paint 38.2 is green and discolours at 200 °C.
  • the third dot of paint 38.3 is yellow and discolours at 250 °C.
  • the fourth dot of paint 38.4 is blue and discolours at 300 °C.
  • the brake pad 30 is provided with a warranty for 50 000 km. Thus if the brake pad is not abused by excessive braking it should be good for at least 50 000 km. If all four dots of paint 38.1 to 38.4 have discoloured, the brake pad 30 was subjected to excessive abuse and a decision can then be made whether or not to honor the warranty claim. If only the first three dots of paint 38.1 to 38.3 have discoloured, then a decision can be made to pay out part of the warranty claim on the basis that 40 000 km of the 50 000 km warranty has been used up. In other words the warranty claim would be reduced by four fifths. Likewise, if only the first two dots of paint 38.1 to 38.2 have discoloured, then the warranty claim would be reduced by three fifths. If only the first dot of paint 38.1 has discoloured, then the warranty claim would be reduced by two fifths. If none of the dots of paint have discoloured, the warranty claim can be paid in full.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Braking Arrangements (AREA)

Abstract

A friction member 10 includes a backing plate 12 with a friction lining 16 and a temperature indicator 20.1 to 20.3 in the form of a temperature sensitive material which will change its colour when subjected to a temperature above a specific level so that a subsequent inspection of the temperature indicator 20.1 to 20.3 will indicate whether or not the friction member 10 was subjected to a temperature above a specific level

Description

DEVICE FOR DETECTING THE MAXIMUM TEMPERATURE OF USE OF A BRAKE PAD LINING
FIELD OF THE INVENTION
This invention relates to a brake pad.
BACKGROUND TO THE INVENTION
A brake pad consists of a metal backing plate to which a friction lining is secured. The life of the friction lining inter alia is dependent on the temperature the lining is subjected to during braking. Hard or excessive braking subjects the friction lining to higher temperatures than normal braking thereby reducing the life of the friction lining.
A brake pad is often sold with a warranty that it can be used for a minimum number of kilometres. When a warranty claim is submitted to a brake pad manufacturer for the friction lining having prematurely worn out, the manufacturer cannot tell if the brake pad was abused by hard or excessive braking which is generally not covered by the warranty.
US patent 4,649,379 to Thomason describes a brake condition indicator. A thermocouple is attached to a brake shoe and to a temperature gauge. The temperature of the brake shoe can be monitored by a driver of a vehicle to provide a warning to the driver in the event of overheating of the brake shoe. It will be appreciated that such a brake condition indicator will not assist a brake pad manufacturer in determining whether or not the brake pad was subjected to excessive temperatures when faced with a warranty claim. SU MARY OF THE INVENTION
According to the invention a friction member having a backing plate and a friction lining includes a temperature indicator in the form of a temperature sensitive material which will change its colour when subjected to a temperature above a specific level so that a subsequent inspection of the temperature indicator will indicate whether or not the friction member was subjected to a temperature above a specific level.
Two or more temperature indicators may be provided with a first temperature indicator undergoing a colour change at a lower temperature than a second temperature indicator and so on. Thus the temperature indicators discolour successively at increasing temperature thresholds. For example three temperature indicators may be provided, the first of which will change its colour at 150°C, the second of which will change its colour at 250°C, and the third of which will change its colour at 350°C.
Each temperature indicator is preferably a different colour before it undergoes a colour change. Thus for example the temperature indicators may be green, orange and red, with the green one turning black at 150°C, the orange one turning black at 250°C, and the red one turning black at 350°C.
The temperature sensitive material may be a heat sensitive paint or a sticker. The paint may be located within blind holes or grooves in the backing plate. Thus the paint may be provided in dots or lines. The holes or grooves may be located side-by-side and may be provided on the rear or the side of the backing plate. The holes or grooves may be less than one millimetre deep, and preferably about 0,5 millimetre deep. It will however be appreciated that the paint could be located on a suitable part of the friction member and that the holes or grooves could be any suitable depth. The friction member may be a brake pad, brake shoe or a clutch plate.
According to another aspect of the invention a method of applying a temperature indicator to a friction member having a backing plate and a friction lining includes the steps of forming a recess in the backing plate and locating a temperature sensitive material within the recess, which temperature sensitive material will change its colour when subjected to a temperature above a specific level.
The recess may be a blind hole or a groove.
According to another aspect of the invention a method of determining the level of abuse to which a friction member was subjected includes the steps of:
providing a friction member having a plurality of indentations each containing a temperature indicator in the form of temperature sensitive paint with each temperature indicator having a different temperature threshold at which it discolours; and
determining which of the temperature indicators have discoloured thereby obtaining an indication of the temperature to which the friction member was subjected and thereby an indication of the abuse to which the friction member was subjected.
The method may include the step of linking the determination of the level of abuse to which the friction member was subjected to an assessment of a warranty claim for the friction member by reducing the warranty claim according to the level of abuse to which the friction member was subjected. BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view of a brake pad according to the invention;
Figure 2 is a cross-section side view on line II - II of figure 1 ; and
Figure 3 is a perspective view of a brake pad according to another embodiment of the invention.
DETAILED DESCRIPTION OF THE DRAWINGS
Referring firstly to figures 1 and 2, a brake pad 10 has a steel backing plate 12 with a front surface 14 to which a friction lining 16 is secured. A rear surface 18 of the backing plate 12 has three spaced blind holes 20.1 to 20.3 about 0,5 mm deep. The holes contain dots of irreversible temperature sensitive paint 22.1 to 22.3.
The dot of paint 22.1 is green and will discolour (turn black) at a temperature of about 150°C. The dot of paint 22.2 is orange and will discolour at a temperature of about 250°C. The dot of paint 22.3 is red and will discolour at a temperature of about 350°C. This temperature range corresponds with the type of braking the brake pad 10 is likely to be subjected to.
After the brake pad 10 has been used, and has for example been returned to the manufacturer for a warranty claim, the manufacturer can determine to what extent, if any, the brake pad was abused. In this regard if none of the dots of paint 22.1 to 22.3 has discoloured then a customer would be entitled to a full warranty claim (100 000 kms). If only the green paint dot 22.1 has discoloured, then the customer would be entitled to 35% of the warranty claim (35 000 kms). If both the green and orange paint dots 22.1 and 22.2 have discoloured, the customer would be entitled to 20% of the warranty claim (20 000 kms). If all three of the paint dots 22.1 to 22.3 have discoloured then the customer would not be entitled to any warranty claim.
Referring now to figure 3, a brake pad 30 has a steel backing plate 32 with a friction lining 34. Four blind holes 36.1 to 36.4 are spaced from one another on the backing plate 32. Each of the holes 36.1 to 36.4 has a different coloured dot of temperature sensitive paint 38.1 to 38.4. The first dot of paint 38.1 is white and discolours by turning light grey at about 150 °C. The second dot of paint 38.2 is green and discolours at 200 °C. The third dot of paint 38.3 is yellow and discolours at 250 °C. The fourth dot of paint 38.4 is blue and discolours at 300 °C.
The brake pad 30 is provided with a warranty for 50 000 km. Thus if the brake pad is not abused by excessive braking it should be good for at least 50 000 km. If all four dots of paint 38.1 to 38.4 have discoloured, the brake pad 30 was subjected to excessive abuse and a decision can then be made whether or not to honour the warranty claim. If only the first three dots of paint 38.1 to 38.3 have discoloured, then a decision can be made to pay out part of the warranty claim on the basis that 40 000 km of the 50 000 km warranty has been used up. In other words the warranty claim would be reduced by four fifths. Likewise, if only the first two dots of paint 38.1 to 38.2 have discoloured, then the warranty claim would be reduced by three fifths. If only the first dot of paint 38.1 has discoloured, then the warranty claim would be reduced by two fifths. If none of the dots of paint have discoloured, the warranty claim can be paid in full.
It will be appreciated that many modifications or variations of the invention are possible without departing from the spirit or scope of the invention.

Claims

1. A friction member including a backing plate with a friction lining and a temperature indicator in the form of a temperature sensitive material which will change its colour when subjected to a temperature above a specific level so that a subsequent inspection of the temperature indicator will indicate whether or not the friction member was subjected to a temperature above a specific level.
2. The friction member of claim 1 wherein two or more temperature indicators are provided, with a first temperature indicator undergoing a colour change at a lower temperature than a second temperature indicator and so on.
3. The friction member of claim 2 wherein each temperature indicator is a different colour before it undergoes a colour change.
4. The friction member of claim 1 wherein the temperature sensitive material is a heat sensitive paint.
5. The friction member of claim 1 wherein the temperature sensitive material is located in an indentation in the backing plate.
6. The friction member of claim 5 wherein the indentation is a blind hole in the backing plate.
7. The friction member of claim 6 wherein the temperature sensitive material is provided in the form of a dot within the blind hole.
8. The friction member of claim 6 wherein the blind hole is less than one millimetre deep and has a diameter of less than one millimetre.
9. The friction member of claim 8 wherein the blind hole is less than 0,5 millimetre deep and has a diameter of less than 0,5 millimetre.
10. The friction member of claim 1 wherein the friction member is a brake pad, brake shoe or clutch plate.
11. A method of applying a temperature indicator to a friction member having a backing plate and a friction lining including the steps of forming an indentation in the backing plate and locating a temperature sensitive material within the indentation, which temperature sensitive material will change its colour when subjected to a temperature above a specific level.
12. The method of claim 11 wherein the indentation is a blind hole or a groove.
13. A method of determining the level of abuse to which a friction member was subjected including the steps of:
providing a friction member having a plurality of indentations each containing a temperature indicator in the form of temperature sensitive paint with each temperature indicator having a different temperature threshold at which it discolours; and
determining which of the temperature indicators have discoloured thereby obtaining an indication of the temperature to which the friction member was subjected and thereby an indication of the abuse to which the friction member was subjected.
14. The method of claim 13 including the step of linking the determination of the level of abuse to which the friction member was subjected to to an assessment of a warranty claim for the friction member by reducing the warranty claim according to the level of abuse to which the friction member was subjected.
15. A friction member substantially as herein described and illustrated with reference to the accompanying drawings.
16. A method of applying a temperature indicator to a friction member substantially as herein described and illustrated with reference to the accompanying drawings.
PCT/IB2004/001085 2003-04-09 2004-04-07 Device for detecting the maximum temperature of use of a brake pad lining WO2004090368A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ZA2003/2766 2003-04-09
ZA200302766 2003-04-09

Publications (1)

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WO2004090368A1 true WO2004090368A1 (en) 2004-10-21

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102005055118A1 (en) * 2005-11-18 2007-05-31 Knorr-Bremse Systeme für Nutzfahrzeuge GmbH Disk brake for vehicles, has disc brake equipped with temperature indicator which changes its condition after exceeding permissible operating temperature or after exceeding permissible temperature in its position
US11326943B2 (en) 2016-02-16 2022-05-10 Carrier Corporation Irradiation decection in data collection devices

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2799167A (en) * 1953-02-12 1957-07-16 Joseph D Loconti Temperature indicators
GB1458956A (en) * 1974-06-10 1976-12-22 Lonza Ag Thermoindicators comprising dinitrile compounds
US4344909A (en) * 1978-12-22 1982-08-17 N.V. Raychem S.A. Thermochromic composition
US4661305A (en) * 1980-07-23 1987-04-28 Raychem Corporation Method of marking a substrate using a markable thermochromic article
US5302940A (en) * 1992-10-05 1994-04-12 Chen Chi Shan Motor vehicle brake detector
US6095289A (en) * 1997-12-23 2000-08-01 Otis Elevator Company Apparatus and method of thermally detecting elevator machine brake
DE19930870A1 (en) * 1999-07-05 2000-09-07 Peter Wernig Temperature sensor comprises material combinations which respond to a temperature rise above a specified threshold by an irreversible color change
DE19936268C1 (en) * 1999-07-31 2001-06-28 Man B & W Diesel Ag Detecting damage to machine part involves using temperature measurement paint with irreversible color change on visible machine part observed after temperature alarm triggered
US20030021975A1 (en) * 2001-07-13 2003-01-30 Roland Martin Oxidation-protected brake disk and method of making same

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2799167A (en) * 1953-02-12 1957-07-16 Joseph D Loconti Temperature indicators
GB1458956A (en) * 1974-06-10 1976-12-22 Lonza Ag Thermoindicators comprising dinitrile compounds
US4344909A (en) * 1978-12-22 1982-08-17 N.V. Raychem S.A. Thermochromic composition
US4661305A (en) * 1980-07-23 1987-04-28 Raychem Corporation Method of marking a substrate using a markable thermochromic article
US5302940A (en) * 1992-10-05 1994-04-12 Chen Chi Shan Motor vehicle brake detector
US6095289A (en) * 1997-12-23 2000-08-01 Otis Elevator Company Apparatus and method of thermally detecting elevator machine brake
DE19930870A1 (en) * 1999-07-05 2000-09-07 Peter Wernig Temperature sensor comprises material combinations which respond to a temperature rise above a specified threshold by an irreversible color change
DE19936268C1 (en) * 1999-07-31 2001-06-28 Man B & W Diesel Ag Detecting damage to machine part involves using temperature measurement paint with irreversible color change on visible machine part observed after temperature alarm triggered
US20030021975A1 (en) * 2001-07-13 2003-01-30 Roland Martin Oxidation-protected brake disk and method of making same

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102005055118A1 (en) * 2005-11-18 2007-05-31 Knorr-Bremse Systeme für Nutzfahrzeuge GmbH Disk brake for vehicles, has disc brake equipped with temperature indicator which changes its condition after exceeding permissible operating temperature or after exceeding permissible temperature in its position
US11326943B2 (en) 2016-02-16 2022-05-10 Carrier Corporation Irradiation decection in data collection devices

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