DE4242084A1 - Friction brake pad wear indicator - uses sensor coil embedded in brake pad exhibiting inductance variation dependent on wear - Google Patents

Friction brake pad wear indicator - uses sensor coil embedded in brake pad exhibiting inductance variation dependent on wear

Info

Publication number
DE4242084A1
DE4242084A1 DE19924242084 DE4242084A DE4242084A1 DE 4242084 A1 DE4242084 A1 DE 4242084A1 DE 19924242084 DE19924242084 DE 19924242084 DE 4242084 A DE4242084 A DE 4242084A DE 4242084 A1 DE4242084 A1 DE 4242084A1
Authority
DE
Germany
Prior art keywords
coil
brake pad
wear
core
arrangement according
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
DE19924242084
Other languages
German (de)
Inventor
Werner Dipl Ing Stumpe
Erich Dipl Ing Dr Zabler
Martin Dipl Ing Blanc
Klaus Dipl Phys Heizmann
Juergen Dipl Ing Wrede
Guenter Dipl Ing Klein
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
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 Robert Bosch GmbH filed Critical Robert Bosch GmbH
Priority to DE19924242084 priority Critical patent/DE4242084A1/en
Publication of DE4242084A1 publication Critical patent/DE4242084A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • B60T17/00—Component parts, details, or accessories of power brake systems not covered by groups B60T8/00, B60T13/00 or B60T15/00, or presenting other characteristic features
    • B60T17/18—Safety devices; Monitoring
    • B60T17/22—Devices for monitoring or checking brake systems; Signal devices
    • 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
    • F16D66/02—Apparatus for indicating wear
    • F16D66/021—Apparatus for indicating wear using electrical detection or indication means
    • F16D66/026—Apparatus for indicating wear using electrical detection or indication means indicating different degrees of lining wear
    • 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
    • F16D66/02—Apparatus for indicating wear
    • F16D66/021—Apparatus for indicating wear using electrical detection or indication means
    • F16D66/026—Apparatus for indicating wear using electrical detection or indication means indicating different degrees of lining wear
    • F16D66/027—Sensors therefor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/02—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness
    • G01B7/06—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness
    • G01B7/10—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness using magnetic means, e.g. by measuring change of reluctance
    • G01B7/105—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness using magnetic means, e.g. by measuring change of reluctance for measuring thickness of coating
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
    • G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
    • 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

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Transportation (AREA)
  • Braking Arrangements (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)

Abstract

The indicator uses a sensor exhibiting a measured value which alters in dependence on the brake pad wear, the variation being monitored via an electronic evaluation stage (5) to activate a display and/or supply a switch signal. The sensor comprises a coil (3) with a soft magnetic core (2) with an E-shaped cross-section, the evaluation stage detecting the variation in the coil inductance. Pref. the resistance value of the coil material varies in dependence on the temp. with the evaluation stage simultaneously monitoring the coil's resistance for measuring the temp. ADVANTAGE - Continuous monitoring of brake pad to provide wear warning signal.

Description

Stand der TechnikState of the art

Anordnungen zur Überwachung des Verschleißes des Belags von Rei­ bungsbremsen sind z. B. aus der DE 41 39 546 A1 bekannt. Dort besteht der Sensor aus mehreren parallel liegenden stromdurchflos­ senen Widerständen, die zeitlich nacheinander durch Verschleiß unwirksam werden. Diese Widerstandsänderung wird durch eine Aus­ werteelektronik überwacht und es wird eine Anzeige und/oder ein Schaltsignal erzeugt wenn eine entsprechende Abnutzung erreicht ist.Arrangements for monitoring the wear of the lining of Rei Exercise brakes are such. B. known from DE 41 39 546 A1. There the sensor consists of several parallel current-free conductors their resistances, which occur in succession due to wear become ineffective. This change in resistance is indicated by an off value electronics monitored and there will be a display and / or a Switching signal generated when a corresponding wear is reached.

Zusätzlich wird ein Widerstandsmaterial gewählt, daß von der Temperatur abhängig ist. Die Auswerteelektronik kann dadurch zusätzlich Rückschlüsse auf die Bremsentemperatur ziehen.In addition, a resistance material is chosen that from the Temperature is dependent. The evaluation electronics can also draw conclusions about the brake temperature.

Vorteile der ErfindungAdvantages of the invention

Auch bei der Erfindung sind nur zwei Anschlüsse für die Überwachung notwendig. Die Änderung erfolgt kontinuierlich. Die Bremsbelagstärke wird erfindungsgemäß kontinuierlich gemessen. Der Sensor trägt an seiner geschlossenen Jochseite eine möglichst flache Spule mit zwei elektrischen Anschlüssen. Der magnetische Kern kann entweder bündig in den Belag eingelassen sein oder etwas versenkt, wenn eine Überwachung erst nach einem gewissen Abnützungsgrad durchgeführt werden soll. Der Kern kann aus normalem, massivem oder geblechtem Eisen sein. Für den Fall, daß dieses Material den Reibprozeß zwischen Belag und Bremsscheibe zu sehr stört, können auch andere ferromagnetische Materialien wie sinterkeramischer Ferrit oder kunststoffgebundener Ferrit verwendet werden.In the invention, too, there are only two connections for monitoring necessary. The change takes place continuously. The brake pad thickness is measured continuously according to the invention. The sensor is wearing its closed yoke side with as flat a coil as possible  two electrical connections. The magnetic core can either be flush with the surface or slightly sunk if one Monitoring only carried out after a certain degree of wear shall be. The core can be made of normal, solid or laminated Be iron. In the event that this material is the rubbing process between the pad and the brake disc is too disturbing, others can ferromagnetic materials such as sintered ceramic ferrite or plastic-bonded ferrite can be used.

Die Schenkel des E-Kerns bzw. die Wände des Topfkerns werden zusammen mit dem Bremsbelag abgeschliffen, so daß sich kontinuier­ lich die Induktivität der Spule ändert, d. h. verkleinert. Der Induktivitätswert läßt sich leicht z. B. mittels einer Oszillator­ schaltung frequenzanalog auswerten, indem man die Spule zum frequenzbestimmenden Glied dieses Oszillators macht (z. B. LR-Relaxationsoszillator oder harmonischer LC-Oszillator). Daneben sind auch zahlreiche andere Schaltungen bekannt, welche eine variable Induktivität elektronisch auszuwerten erlauben. Die an der geschlossenen Seite des Kerns liegende Spule, deren Wicklung z. B. aus Cu-Draht aufgebaut ist, kann gleichzeitig auch als Temperatur­ fühler benutzt werden, denn Cu besitzt einen beträchtlichen Wider­ stands-Temperaturkoeffizienten von ca. 4,3 · 10-3/K. Die Aus­ wertung kann hier ebenfalls frequenzanalog oder aber auch gleich­ strommäßig z. B. in einer Wheatstonebrücke erfolgen. Für extrem hohe Temperaturen können natürlich auch andere Drahtmaterialien wie beispielsweise Pt, Ni, W, Mo, Ti usw. verwendet werden. Bei der Wahl des ferromagnetischen Kernmaterials ist zu beachten, daß die zu erwartende Betriebstemperatur unterhalb des für den Werkstoff gültigen Curie-Punktes (bei Fe ca. 800°C, bei Ferrit ca. 500°C) liegt. The legs of the E core or the walls of the pot core are ground together with the brake pad, so that the inductance of the coil changes continuously, ie reduced. The inductance value can be easily z. B. by means of an oscillator circuit to evaluate frequency analog by making the coil the frequency-determining element of this oscillator (z. B. LR relaxation oscillator or harmonic LC oscillator). In addition, numerous other circuits are known which allow variable inductance to be evaluated electronically. The coil lying on the closed side of the core, the winding z. B. is built of copper wire, can also be used as a temperature sensor, because Cu has a considerable resistance temperature coefficient of about 4.3 · 10 -3 / K. The evaluation can also be frequency-analog or equally current z. B. in a Wheatstone bridge. For extremely high temperatures, other wire materials such as Pt, Ni, W, Mo, Ti etc. can of course also be used. When choosing the ferromagnetic core material, it should be noted that the expected operating temperature is below the Curie point valid for the material (approx. 800 ° C for Fe, approx. 500 ° C for ferrite).

Während das Joch des magnetischen Kernes bzw. auch die Spule in der oben beschriebenen Anordnung im Verschleißbereich des Bremsbelags liegt, kann sie auch so angebracht werden, daß Joch und Spule aus der nicht aktiven Seite des Bremsbelags heraus ragen und so gänzlich vor Zerstörung gesichert bleiben.While the yoke of the magnetic core or the coil in the Arrangement described above in the wear area of the brake pad lies, it can also be attached so that the yoke and coil out stick out of the inactive side of the brake pad and so completely remain safe from destruction.

Man kann weiterhin den elektrisch leitfähigen Spulenkern auch noch z. B. zusammen mit einem Anschluß der Wicklung kontaktieren und so auch ein Berühren des Kerns mit der leitfähigen Bremstrommel oder Bremsscheibe als elektrische Kontaktgabe sehr genau erfassen.You can still use the electrically conductive coil core e.g. B. together with a connection of the winding and so also touching the core with the conductive brake drum or Record the brake disc very precisely as an electrical contact.

FigurenbeschreibungFigure description

Anhand der Zeichnung werden Ausführungsbeispiele der Erfindung erläutert.Exemplary embodiments of the invention are shown in the drawing explained.

In Fig. 1 ist mit 1 ein Teil eines Bremsbelages bezeichnet, in den ein E-Kern 2 mit Spule 3 eingebettet ist; 4 ist die Bremsscheibe. Die beiden Spulenenden sind herausgeführt (Leitungen 8a und 8b) und mit einer Auswerteelektronik 5 verbunden. Das eine Spulenende ist bei 6 noch zusätzlich mit dem Kern verbunden. Eine weitere Ver­ bindung 7 führt zur Bremsscheibe 4.In Fig. 1, 1 denotes a part of a brake pad in which an E core 2 with a coil 3 is embedded; 4 is the brake disc. The two coil ends are led out (lines 8 a and 8 b) and connected to an evaluation electronics 5 . One end of the coil is additionally connected to the core at 6 . Another Ver connection 7 leads to the brake disc 4th

Die Auswerteschaltung 5 kann über die Leitungen 8a und 8b erkennen, wenn sich durch Abrieb die Induktivität ändert. Gleichzeitig kann sie erkennen, ob sich der Widerstand der Spule ändert und damit auf die Bremsentemperatur schließen. Über die Leitungen 7 und 8a läßt sich erkennen, wenn der Kern 2 mit der Bremsscheibe 4 in Berührung kommt.The evaluation circuit 5 can detect via the lines 8 a and 8 b when the inductance changes due to abrasion. At the same time, it can recognize whether the resistance of the coil changes and thus deduce the brake temperature. Via the lines 7 and 8 a can be seen when the core 2 comes into contact with the brake disc 4 .

Fig. 2 zeigt den Belag 1 der Fig. 1, wenn er bis zur Linie 9 abgenutzt ist und ein Austausch erfolgen muß. Fig. 2 steht auch für den Fall, daß der Kern 2 von Anfang an mit abgenutzt werden soll. Fig. 2 shows the covering 1 of Fig. 1 when it is worn down to line 9 and an exchange must take place. Fig. 2 also stands for the case that the core 2 is to be worn from the beginning.

Fig. 3 zeigt einen Belag, bei dem ein Topfkern 2′ samt Spule 3′ im nicht aktiven Teil des Belags befestigt ist und teilweise aus dem Belag 1′ herausragt. Hier wird die Induktivitätsänderung allein durch die Änderung der Belagdicke bewirkt. Fig. 3 shows a covering in which a pot core 2 'together with the coil 3 ' is fixed in the inactive part of the covering and partially protrudes from the covering 1 '. Here the change in inductance is brought about solely by changing the thickness of the covering.

Claims (6)

1. Anordnung zum Erkennen des Verschleißes des Belags einer Reibungsbremse, mit einem Sensor, der mit fortschreitendem Belag­ verschleiß seinen Meßwert ändert, wobei diese Änderung durch eine Auswerteelektronik überwacht wird, die eine Anzeige bewirkt und/oder ein Schaltsignal erzeugt, dadurch gekennzeichnet, daß der Sensor eine Spule mit weichmagnetischem E- oder Topfkern ist, und daß die Änderung der Induktivität der Spule durch die Auswerteelektronik überwacht wird.1. Arrangement for detecting the wear of the lining of a friction brake, with a sensor that changes its measured value with wear of the lining, this change being monitored by evaluation electronics which cause a display and / or generate a switching signal, characterized in that the Sensor is a coil with a soft magnetic E or pot core, and that the change in the inductance of the coil is monitored by the evaluation electronics. 2. Anordnung nach Anspruch 1, dadurch gekennzeichnet, daß das Spulenmaterial in seinem Widerstandswert von der Temperatur abhängig ist und daß zusätzlich zur Temperaturbestimmung der Widerstand der Spule durch die Auswerteelektronik überwacht wird.2. Arrangement according to claim 1, characterized in that the Coil material in its resistance value depends on the temperature and that in addition to determining the temperature, the resistance of the Coil is monitored by the evaluation electronics. 3. Anordnung nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß der Kern im Belag derart eingebettet ist, daß nach einem teilweisen Verschleiß die Schenkel und/oder Wände des E- bzw. Topfkerns mit­ verschlissen werden. 3. Arrangement according to claim 1 or 2, characterized in that the Core is embedded in the covering in such a way that after a partial Wear the legs and / or walls of the E or pot core with be worn out.   4. Anordnung nach Anspruch 3, dadurch gekennzeichnet, daß der Spulenkern mit einem der Spulenanschlüsse verbunden ist und ein weiterer Anschluß mit der Bremstrommel oder Bremsscheibe hergestellt ist und daß die Berührung der beiden Teile von der Auswerte­ elektronik überwacht wird.4. Arrangement according to claim 3, characterized in that the Coil core is connected to one of the coil connections and one further connection with the brake drum or brake disc is and that the touch of the two parts of the evaluation electronics is monitored. 5. Anordnung nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß der Kern im Belag derart eingebettet ist, daß die Schenkel und/oder Wände des E- bzw. Topfkerns von Anfang an mitverschlissen werden.5. Arrangement according to claim 1 or 2, characterized in that the Core is embedded in the covering in such a way that the legs and / or Walls of the E or pot core are also worn from the start. 6. Anordnung nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß der Kern außerhalb des aktiven Teil des Belags untergebracht ist.6. Arrangement according to claim 1 or 2, characterized in that the Core is housed outside the active part of the covering.
DE19924242084 1992-12-14 1992-12-14 Friction brake pad wear indicator - uses sensor coil embedded in brake pad exhibiting inductance variation dependent on wear Withdrawn DE4242084A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE19924242084 DE4242084A1 (en) 1992-12-14 1992-12-14 Friction brake pad wear indicator - uses sensor coil embedded in brake pad exhibiting inductance variation dependent on wear

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19924242084 DE4242084A1 (en) 1992-12-14 1992-12-14 Friction brake pad wear indicator - uses sensor coil embedded in brake pad exhibiting inductance variation dependent on wear

Publications (1)

Publication Number Publication Date
DE4242084A1 true DE4242084A1 (en) 1994-06-16

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DE19924242084 Withdrawn DE4242084A1 (en) 1992-12-14 1992-12-14 Friction brake pad wear indicator - uses sensor coil embedded in brake pad exhibiting inductance variation dependent on wear

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001079724A1 (en) * 2000-04-19 2001-10-25 Federal-Mogul Technology Limited Method and sensor for measuring wear in brakes
DE19548520B4 (en) * 1995-12-22 2004-07-08 Linde Ag Method for determining the air gap thickness of a clutch, in particular a brake, and device provided therefor
EP2149721A1 (en) * 2008-07-30 2010-02-03 Honeywell International Inc. Method, system and apparatus for friction pad wear and brake condition monitoring
DE102012012830A1 (en) * 2012-06-28 2014-01-02 Knorr-Bremse Systeme für Nutzfahrzeuge GmbH Disc brake of a motor vehicle
CN112135984A (en) * 2018-05-17 2020-12-25 意大利Itt有限责任公司 Vehicle brake system
US11168752B2 (en) * 2014-09-08 2021-11-09 Itt Italia S.R.L. Method for manufacturing a sensorized braking element, in particular a brake pad and a sensorized brake pad obtained thereby
DE102018107158B4 (en) 2018-03-26 2023-04-27 Knorr-Bremse Systeme für Schienenfahrzeuge GmbH Measuring system and measuring method for determining wear of a brake pad of a friction brake

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19548520B4 (en) * 1995-12-22 2004-07-08 Linde Ag Method for determining the air gap thickness of a clutch, in particular a brake, and device provided therefor
WO2001079724A1 (en) * 2000-04-19 2001-10-25 Federal-Mogul Technology Limited Method and sensor for measuring wear in brakes
EP2149721A1 (en) * 2008-07-30 2010-02-03 Honeywell International Inc. Method, system and apparatus for friction pad wear and brake condition monitoring
US7877216B2 (en) 2008-07-30 2011-01-25 Honeywell International Inc. Method, system, and apparatus for friction pad wear and brake condition monitoring
DE102012012830A1 (en) * 2012-06-28 2014-01-02 Knorr-Bremse Systeme für Nutzfahrzeuge GmbH Disc brake of a motor vehicle
EP2867557B1 (en) 2012-06-28 2018-04-18 KNORR-BREMSE Systeme für Nutzfahrzeuge GmbH Disc brake of a motor vehicle
US11168752B2 (en) * 2014-09-08 2021-11-09 Itt Italia S.R.L. Method for manufacturing a sensorized braking element, in particular a brake pad and a sensorized brake pad obtained thereby
DE102018107158B4 (en) 2018-03-26 2023-04-27 Knorr-Bremse Systeme für Schienenfahrzeuge GmbH Measuring system and measuring method for determining wear of a brake pad of a friction brake
CN112135984A (en) * 2018-05-17 2020-12-25 意大利Itt有限责任公司 Vehicle brake system
CN112135984B (en) * 2018-05-17 2023-03-28 意大利Itt有限责任公司 Vehicle brake system

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