FR2482229A1 - BRAKE LINING WEAR WARNING DEVICE FOR MOTOR VEHICLE - Google Patents

Abstract

SEVERAL DIFFERENT DETECTION ZONES ARE NECESSARY, THIS WEAR WARNING DEVICE CONTAINS SEVERAL DETECTION CIRCUITS 11A, 11B, 11C MOUNTED IN PARALLEL FOR CHECKING THE SUPPLY CIRCUIT OF A GENERAL WARNING UNIT 10. FOLLOWING THE INVENTION, IT IS ALSO ASSOCIATED WITH EACH OF THESE DETECTION CIRCUITS 11A, 11B, 11C WITH AN INDIVIDUAL WARNING UNIT 29A, 29B, 29C, A SINGLE LIGHT-DRIVE DIODE FOR EXAMPLE, TO LOCATE THE DETECTION ZONE INTERESTED WHEN ACTING INTO ACTION OF THE GENERAL WARNING BOARD 10. APPLICATION TO BRAKE LINING WEAR WARNING DEVICES FOR MOTOR VEHICLES.

Description

The present invention relates generally to devices

  brake lining wear warning devices for a motor vehicle of the kind comprising an element

  a warning light, in practice a warning light, whose

  is under the control of a detection circuit

  driven by a wear sensor, for example a simple conductive

  in the brake lining to be checked.

  Such a wear warning device is particularly

  described in the French patent filed under the

  No. 74 26272 and published under No. 2,238,621.

  The present invention relates more particularly to the case where, for the same motor vehicle, several zones

  different detection are to consider.

  For example, it can be the various axles of a

  vehicle, or, for the same axle of that vehicle,

  wheels that includes such an axle.

  For a trailer vehicle, it can also be the tractor that includes such a vehicle, or the trailer

which is hitched to him.

  In such a case, it is customary to provide as many

  separate sensing bake that there are detection zones

  to consider, by assigning each of them respectively to

  these, and to mount in parallel these various detection circuits for controlling a mime warning member, hereinafter general warning member, the latter being

  thus common to all the detection circuits.

  But in such a case, when the general warning member comes into action, thus indicating to the user that one of the brake lining of his vehicle has reached a determined degree of wear, it is not possible to this user

  to know immediately which of the various zones of de-

  tection actually concerned by such wear and tear

brake lining.

  However, such knowledge is desirable, because on the road, it can influence the mode of driving to adopt, and, on the ground, during the intervention to be performed to change the used brake lining, it avoids having to proceed to a systematic search, by trial and error, of this filling. In addition, in the case of a trailer vehicle whose tractor may have a mileage different from that of the trailer, it may be advantageous on the road to know whether the wear reported affects the brakes of said tractor or

those of said trailer.

  The present invention generally has the

  object a wear warning device responding in such a manner

  this purpose and furthermore

advantageous features.

  More specifically, the subject of the present invention is a wear warning device of

  brake for a motor vehicle of the kind comprising an

  a general warning light, for example a light, whose supply circuit is under the control of

  two separate detection circuits mounted in parallel

  and respectively assigned to zones of detection.

  different axles of such a vehicle for example, or different wheels of the same axle thereof, this device being characterized in that it is associated with each of the detection circuits a warning member

  for the location of the detection zone

  during the entry into action of the advisory body

general situation.

  Preferably, and in a very simple manner, each of the detection circuits comprising an orientation diode to avoid its looping on another, such an orientation diode is a light-emitting diode, so that it constitutes by itself the warning organ

  individual associated with such a detection circuit.

  Thus, when one of the brake linings of a certain

  the detection zones achieve a sufficient degree of wear

  to bring into action the body of warning

  In general terms, the light-emitting diode of the detection circuit associated with this detection zone lights up together with said input into action, thereby indicating to the user which of the detection zones is

  concerned by such brake lining wear.

  In other words, the lack of wear is immediately located.

  Preferably, the wear warning device

  In accordance with the invention, there is furthermore associated a test circuit, said test circuit comprising a clean oscillator.

  to inject pulsed power into the circuits of de-

  detection of said device, under the control of a delay capacitor adapted to inhibit said oscillator after charging. Thus, each time the device is powered up, and therefore, in practice, at each closure of the general circuit

  the vehicle concerned, the warning

  of the wear warning device according to the

  vention, as well as the individual warning

  associated with it, are subject to periodic feeding

  during the charging time of the capacitor

  delay of the test circuit, thereby signaling

  systematically, to the user, that they are in good working order.

  If desired, it is associated with the delay capacitor

  a discharge circuit controlled by a push button at the disposal of the user, so that it, en route,

  may at any time control, following the preceding process

  the good working order of the warning

  general and individual warning

are associated with it.

  These characteristics, as well as others, and their

  tages, will emerge moreover from the description which will

  to follow, by way of example, with reference to the appended drawing, the single figure of which is a diagram of the warning device

according to the invention.

  This diagram illustrates the application of the invention to the case where, with respect to the equipment of a trailer vehicle,

  three different detection zones A, B, C are considered

  namely, the front axle of the towing vehicle, the rear axle thereof, and the axle or

  the set of axles of the trailer.

  In such a case, for the control of the power supply of a general warning device 10, a single indicator light for example, as shown, three separate detection circuits 11A, 11B, 11C are provided, which, mounted in parallel, are each respectively assigned to the various detection zones A, B, C.

  For its food, the general warning

  10 is connected between the positive terminal B + of a DC power source, in practice the battery of the vehicle concerned, or that of the tractor of this vehicle when it is a trailer vehicle, and the mass, in series with, on the one hand, a current limiting resistor 12, and a switch 13 which is under control of the circuits

Detection IIA, 11B, 11C.

  In the exemplary embodiment shown, this

  controlled switch 13 is a transistor, suitably connected

  and, for reasons which will appear hereinafter, it is

  shunted by a bypass having a diode of orienta-

  tion 14 established in such a way as to correspond to a food

  reverse direction of the general warning device 10.

  Of course, on this diet was also

  interposed a general switch 15 which is under the con-

  control of the ignition key of the vehicle.

  On the power supply of the detection circuits 11, IIB,

  11C is established an orientation diode 16 disposed of

  to oppose a reverse feeding of these cir-

baked detection.

  The power supply circuit of the warning device

  10 is connected upstream of this diode of orienta-

16.

  The detection circuit 11A, 11B, of each of the detection zones A, B comprises a resistance bridge 18A, 18B on which is mounted in series at least one wear sensor

19A, 19B.

  In practice, with regard to the front axle and the

  rear seat of a vehicle, two wear sensors 19A, 19B at least are provided, one for each wheel of such an axle. As shown, and in a manner known per se, it

  U-shaped conductors, which are arranged in the

  brake deposition, at a distance from the free surface thereof before wear, and whose concavity is

directed towards this free surreal.

  These wear sensors 19A, 19B are connected by means of

  disengageable connections 20A, 20B on the spring bridges

these 18A, 18B corresponding.

  In the exemplary embodiment shown, each of

  these resistor bridges 18A, 18B are formed of three resistor

  between the B + terminal and the mass, namely

  upstream of the wear sensors 19A, 19B, a first resistance

  22A, 22B, and, downstream of said sensors, two resistors

  23A-23B and 24A-24B.

  In practice, all these resistances are likewise

their.

  The remainder of each detection circuit 11A, 11B includes

  a link is established between the mid-point MA, MB of the corresponding resistors 23A-24A, 23B-24B, on the one hand, and the controlled switch 13, on the other hand,

  this link resulting in practice on the basis of the

  sistor constituting said controlled switch 13.

  On such a link are successively interposed, in the exemplary embodiment represented, an inverter 26A, 26B, which is associated with a protection circuit 27A, 27B, a resistor 28A, 28B, and an orientation diode 29A, 29B, for avoid looping of a detection circuit 11A,

11B on the other.

  The detection circuit 11C has, overall, a construction

  similar to that described above.

  However, in the case of a detection circuit assigned to a detection zone constituted by the axle or set of axles of a trailer, two resistance bridges 180, 18'C are provided in parallel, one , 18'C, which is formed of two resistors 22'0, 24'C of a first value, equal in practice to that of resistors resistance bridges

  18A, 18B, and on which are mounted in series the cap-

  1909 associated with the other 1809 which is formed of three resistors 220, 230 and 240 of a second value, multiple of the previous one, and to which is connected the first by a disengageable connection 200, the latter being established between on the one hand, the mid-point of the resistor bridge 18'C, downstream of the wear sensors 19C, and, on the other hand, the midpoint of the resistors 220, 230 and the bridge of resistance

sistances 180 -

  The resistance bridge 18'C, with the wear sensors C, is established between a terminal B '+ connected by wire to the

  terminal B + (not shown in the figure), and the mass, tan-

  say that the bridge of resistors 180 is established, in parallel

  with the bridges of resistances 18A, 18B, and according to the

  previous edition, between the B + terminal of the battery of the

tractor hitch and mass.

  As previously, the remainder of the detection circuit 11c is connected to the midpoint MC of the resistors 23C, 240 of the resistor bridge 18C and comprises an inverter 260, with a protection circuit 270, a resistor 28C, and a diode

guidance 290.

  According to the invention, each of the detection circuits 11A, 11B, 110 is associated with an individual warning member for locating the detection zone A, B,

  C interested in the entry into action of the body of warning

General 10.

  In practice, and as shown, the diode orients

  29A, 29B, 290 such a circuit of detection

  114, 11B, 110 is an electroluminescent diode, in

  so that it constitutes in itself the advisory body

  individually associated with this circuit.

  As shown schematically by a broken line 30 in the figure, the diodes 29A, 29B, 29C are assembled on the front of the wear warning device according to the invention, with

  the general warning body 10.

  For safety reasons, in the example of

  shown, for supplying the components of the detection circuits 11A, 11B, 110, a direct current source 32, which, powered by the terminal B + of the battery

  of the towing vehicle, delivers, in accordance with

  naked in themselves, on a terminal b +, a voltage

advantageously stabilized.

  To the wear warning device thus constituted, it is preferably associated, according to the invention, and as shown, a test circuit 34, this test circuit 34 comprising an oscillator 35 capable of injecting a pulsed power supply into the detection circuits 11A, 11B, 110

  of this device, by means of diodes of

  36A, 36B, 360, and under the control of a delay capacitor 37 adapted to inhibit said oscillator 35

  after charging, one of the terminals of this time capacitor

  37 being connected to said oscillator 35 via

  in the example shown, an inverter 38 and

of an orientation diode 39.

  The charge circuit of the delay capacitor 37 is connected between the terminal b + of the DC stabilized source and the ground, and has a resistor

current limiting device 40.

  For discharge of the delay capacitor 37, the resistor 40 is looped by a bypass comprising a

orientation diode 41.

  In addition, pref erence @ 5 and as shown, to the delay capacitor 27 is associated a second discharge circuit controlled by a push button 43 at the disposal of the user, the second discharge circuit having a limiting resistor current 44 and a

  switch contact 45 controlled by the push button 43.

  Finally, preferably, and as shown, in series with the general warning member 10 is mounted a resistor. of current limitation 47, and this is

  shunted by a bypass having a switch

  48, a simple transistor for example, slaved to the

  of a control point K, which belongs in practice to

  than its basic circuit and which is connected to a sen-

  K 'belonging to the supply circuit of any

  vehicle lighting unit 50, night light or fire

  crossing for example; in the exemplary embodiment

  presented, two resistors 51, 52 are provided for in this

  cooked basic, and the control point K is further connected

to the ground by a resistance 53.

  The various components of the various circuits involved

  are well known by themselves and, likely to

  technically equivalent, they will not be described in more detail here. We will first assume that all the trimmings

  brakes to control are new.

  In other words, with each braking, none of the sensors

  19A, 19B, 19C comes into contact with the rotational member

corresponding braking force.

  As soon as the general switch 15 is closed, it becomes

  establishes, at the middle point MA, MB, MC of the resistance bridges

  18A, -18B, 18C a determined potential level, sensitive

  equal to one third of the potential present at each

one of these bridges.

  Except for the moment of the test circuit 34, it follows that, given the inverters 26k, 26B,

  260, the light-emitting diodes 29A, 29B, 290

  inert, and that the transistor constituting the interrup-

  controlled 13 being blocked, the same is true for the

general warning 10.

  On the other hand, if, because of the wear of the brake lining in which it is embedded, one of the wear sensors

  19A, 19B, 190 is flush with the surface of this garniture

  brake, and therefore, when braking,

  tact of the corresponding rotary member to brake, which is

  the mass, the potential at the middle point MA, MB, MC correspon-

  at the detection zone o is the wear sensor in question abruptly cancels out, or, in other words, passes

  at a second level, distinct from the previous one.

  Given the inverter that the circuit of

  corresponding detection 11A, 11B, 11c, on the one hand the

  the sistor constituting the controlled switch 13 is saturated, so that this transistor becomes on and that, the supply circuit of the warning deviceEntgénkall0 is therefore closed, this general warning member

  in action, and on the other hand the light-emitting diode

  the corresponding 29k, 29B, 290 is itself excited.

  Thus, according to the invention, the user of the vehicle

  simultaneously with the signaling of a wear defect, the detection zone in which this

lack of wear.

  As a first step, the signaling process described above only occurs during braking, and

stop with him.

  In a second step, when the wear of the packing

  brake has become sufficient for the corresponding wear sensor, itself subject to similar wear, to be split into two elements, which interrupts the continuity of the relevant detection circuit, the point

  MA medium, IiB, MC corresponding is permanently connected

  to the ground by the associated resistor 24A, 24B, 240, so that the signaling process described above

becomes permanent himself.

  In practice, when closing the general switch 15, the delay capacitor 37 of the test circuit 34 is discharged, so that, in view of the inverter 38, the oscillator 35 of this test circuit between

  in action simultaneously with this closure ..

  By means of the orientation diodes 36A, 36B, 360, this results in application to the detection circuits 11A, 11B, 110, upstream of their inverter 26A, 26B, 260,

  each pulse, of this oscillator 35, of a po-

  tential corresponding to that of the -masse.

  Everything happens as if, with each pulse

  oscillator 35, a simultaneous

  The signaling process described previously between cyclically in action, wears on each of the detection circuits 11A, 11B, 11C, and interests all the light-emitting diodes 29A, 29B, 290 together with the general warning member. 10, By such a systematic signaling process

  pulsed at startup, the user knows that the circuits of de-

  detection of the wear warning device of which is equipped

  his vehicle are in good working order.

  This process continues until, through resistor 40, the charge of the delay capacitor

  37 sufficient to provoke, in view of the inver-

  38, stopping the oscillator 35, which, in practice,

  intervenes after a few seconds.

  By the push button 43, the user can, at his discretion

  tion, cause a discharge of the delay capacitor

  tion 57 through the resistor 44, which causes a new

  the process of systematic pulsed signaling, as before. The user can, thus, check from time to time, whether

  on the way, the good working condition of the cir-

detection bake 11A, 11B, 11c.

  When opening the main switch 15, the

  delay capacitor 37 discharges systematically

  in the resistor 40, by the orientation diode 41.

  As will have been noted, with the wear warning device according to the invention, the permanent signaling process due to sufficient lining wear to have caused the opening of the corresponding detection circuit.

  intervene only because of the mere physical phenomenon of opening

  of such a circuit, by wear of the corresponding sensor,

  and not because of any eventual

parasite.

  Moreover, the duplication, according to the invention, of

  resistance bridge associated with the particular protection zone

  what a possible trailer would

  the disconnection of it without the result

  an inadvertent triggering of the signaling process.

  Indeed, while, given the great value

  relative resistances 220, 230 and 240 of the resistance bridge

  180, which can be of ten times greater value than the resistors 22'0 and 24'0 of the bridge of resistances 18'C, only intervene in practice, when the trailer

* is connected, these resistances 22'C, 24'0 of the bridge of resistance

  18'0 on which the wear sensors are inserted

  corresponding on the same trailer.

  On the other hand, when it is disconnected,

  22C, 23C, 240 of the resistor bridge 180 installed in the towing vehicle are in turn

  to ensure at the LHC midpoint the level of potential for

  which the corresponding detection circuit 110, and therefore

  the general warning device 10, remain inactive.

  The simple connection or disconnection of the trailer does not interfere in any way with the practical state of this circuit

detection 110.

  It should also be noted that this connection or disconnection does not advantageously involve

monofilar connection.

  If, during assembly of the wear warning device according to the invention, a mounting error leads to a polarity inversion at the terminals of this device, the terminal B + of the direct current source being substituted for ground, and reciprocal the supply circuit of the general warning member 10 is closed by the orientation diode 14 ,, and it alone, thereby signaling

  the operator his mistake maour.,.

  Together, the orientation diode 16 saves low level components of the device the effects of such a device.

  reverse polarity, and thus prevents them from

  Similarly, the inverters 26A, 26B, 260 are supported by their protection circuit 27A, 27B, 270, and the oscillator 55 is also spared, because of an orientation diode 46 which then flows. the surplus of

  potential towards the terminal b-- of the source of cou-

stabilized continuous stream 32.

  The device according to the invention is therefore self-protected.

  By day, the lighting member 50 of the vehicle is

  normally not in use, and the potential of the point of contact

  Mande XK is therefore zero, the sensitive point KI being connected to the ground by said lighting member 500 As a result, the controlled switch 48 is saturated, and "closed" state: it short-circuits the current limiting resistor 47, and if necessary, according to the process described above, the general warning member

  is powered at full load.

  At night, on the other hand, since the power supply circuit of the lighting element 50 is closed, the potential of the control point K is brought to a determined value, sufficient to cause, given the resistors 51, 52, the blocking the controlled switch 48; this one

  thus being "open", the

  rant 47 is put back into service, so that, if necessary, the power of the general warning member 10 is reduced load, which, in practice as a light, reduces the brightness, and thus household

advantageously the driver.

  As will be understood, the resistance 53, in

  substitute for the lighting member 50, allows, if the

  between the points K and K 'has not been carried out, a full load power supply, if any, of the general warning device 10, the controlled switch 48 is

finding then saturated.

  Of course, the present invention is not limited to

  the embodiment described and shown, but

be any variant of execution.

  In particular, although it is particularly

  to take advantage of the implementation of diodes in

  detection circuits to form warning devices

  These individual warning devices could be designed independently, their own power supply

  being under the control of the corresponding detection circuit

laying.

REVEIDICATIONS

  1. Pad wear warning device

  brake for a motor vehicle of the kind comprising an

  a general warning light, for example a light, whose power circuit is under the control of

  two separate detection circuits mounted in parallel

  and respectively assigned to zones of detection.

  different axles of such a vehicle for example, or different wheels of the same axle thereof, characterized in that it is associated with each of the detection circuits an individual warning member, for localization of the detection area concerned during

  the entry into action of the general warning body.

  2. Device according to claim 1, characterized in that, each of the detection circuits comprising an orientation diode, to avoid looping on another,

  such an orientation diode is a light emitting diode

  so that it constitutes by itself the individual warning device associated with such a circuit of

detection.

  3. Device according to any one of the claims

  1, 2, in which a switch, driven by the cir-

  detection, is interposed on the feed circuit.

  of the general warning device, characterized in that

  said switch is shunted by a shunt

  an orientation diode established in such a way as to correspond

  to a reverse supply of said warning member

  general and thus report any mounting error.

  4. Device according to any one of the claims

  1 to 3, wherein an orientation diode is established

  on the supply of detection circuits by being

  in such a way as to oppose a reverse supply thereof, characterized in that the supply circuit of the general warning member is connected upstream of the

said diode orientation.

  5. Device according to any one of the claims

  1 to 4, wherein the detection circuit of each of the detection zones comprises a resistance bridge on which is mounted in series a wear sensor, characterized in that, for at least one of said detection zones, two resistor bridges are provided in parallel, one formed of resistors of a first value, on which is mounted in series the associated wear sensor, the other formed of resistors of a second value, multiple of the previous one, to which is connected the first by a disengageable connection, and on which is connected the rest of the detection circuit

concerned.

  6. Device according to any one of the claims

  1 to 5, characterized in that it is associated with

  test circuit, said test circuit comprising an oscillator

  a device capable of injecting a pulsed power supply into the detection circuits of said device, under the control of a delay capacitor capable of inhibiting said

oscillator after charge.

  7. Device according to claim 6, characterized in that said delay capacitor is associated with a discharge circuit controlled by a push button at the

provision of the user.

  8. Apparatus according to any one of the

  1 to 7, characterized in that, in series with the

  general warning has mounted a limiting resistance

  current, and in that it is shunted by a bypass having a controlled switch controlled by the potential of a control point connected to a sensitive point belonging to the supply circuit of any of the lighting members of the vehicle, so that said switch is open when said lighting member

  is in use, and closed otherwise.

  9. Device according to claim 8, characterized in that said control point is connected to the ground by

a resistance.