DE102017131252A1 - Disc brake with a Lüftspielüberwachungsvorrichtung, Lüftspielüberwachungsvorrichtung for a brake, and method of operating such Lüftspielüberwachungsvorrichtung - Google Patents

Abstract

A disc brake (1), preferably pneumatically operated, in particular for a motor vehicle, comprises a brake caliper (2) overlapping brake caliper (2), two brake linings (3, 3 ') arranged in opposite directions in the brake caliper (5), an application device (ZV) , an adjusting device (NV) and a clearance monitoring device (6). The clearance monitoring device (6) has at least one sensor (7, 8, 9) for structure-borne noise and an evaluation unit (10). A clearance monitor for a brake and a method for operating a clearance monitor (6) are provided.

Description

The invention relates to a disc brake with a Lüftspielüberwachungsvorrichtung according to the preamble of claim 1. The invention also relates to a Lüftspielüberwachungsvorrichtung and a method for operating such Lüftspielüberwachungsvorrichtung.

Friction brakes in commercial vehicles are subject during their use wear of brake disc and brake pads. This wear is compensated by a wear adjustment to always ensure a constant distance between brake pads and brake disc in the unactuated state of the brake. This distance is called a clearance.

Too large a clearance has a negative effect on the response, controllability and maximum clamping force of a brake application device. Too small a clearance leads to unnecessary concern of the brake pads on the brake disc in the unactuated state and thus to increased wear of the friction pairing, increased residual grinding torque and thus increased fuel consumption and in very unfavorable operating conditions to a so-called hot runner.

Due to a malfunction of the wear adjuster or other involved in the adjustment process components or faulty maintenance can lead to a too large or too small clearance, which can not be safely detected by the driver or by a workshop.

A robust functional fulfillment of the wear adjustment should prevent an unsuitable clearance. In addition, inspections are carried out to check the clearance on the vehicle.

Therefore, the object of the present invention is to provide a disc brake with an improved Lüftspielüberwachungsvorrichtung, at the same time a cost-effective construction is desired.

Another object is to provide an improved clearance monitoring device.

Yet another object is to provide a method for operating such a clearance monitoring device.

A solution to the problem is created by the subject matter of claim 1.

The further object is achieved by a Lüftspielüberwachungsvorrichtung with the features of claim 8.

The still further object is achieved by the method according to claim 13.

One idea of the invention is to measure and evaluate the structure-borne sound at a suitable location of the brake in order to determine a clearance that is too great or too small.

A disc brake according to the invention, preferably compressed air actuated, in particular for a motor vehicle, has a brake caliper over a brake caliper, two arranged in the caliper, oppositely movable brake pads, a brake application device, an adjusting device and a Lüftspielüberwachungsvorrichtung on. The clearance monitoring device comprises at least one pick-up for structure-borne noise and an evaluation unit.

Thus, it is advantageously possible to distinguish the correct clearance of the malfunction of a too large or too small clearance based on the characteristic structure-borne noise.

An inventive Lüftspielüberwachungsvorrichtung has at least one sensor for structure-borne noise and an evaluation unit wherein the at least one sensor for structure-borne noise is provided for attachment to a structure of the brake to be assigned. For a simple construction is advantageously possible.

An inventive method for operating the above-mentioned Lüftspielüberwachungsvorrichtung on a brake, wherein the Lüftspielüberwachungsvorrichtung has at least one transducer for structure-borne noise and an evaluation, wherein the at least one sensor for structure-borne noise is provided for attachment to a structure of the brake to be assigned comprises the method steps S1 Detecting a structure-borne sound signal by means of pickup (s) on a structure of a brake; S2 Detecting a first pulse in the structure-borne sound signal together with an amplitude of the first pulse at a first time and detecting a second pulse having a respective amplitude at a further time and comparing it with a predetermined amplitude of a correct air gap; and S3 Too small a clearance if too small an amplitude is found in the comparison of the amplitudes, or to show a too large clearance if the amplitude is compared with the amplitude too large. In this way, there is the advantage, the correct clearance of the malfunction of too large or too small clearance based on the characteristic structure-borne sound easy to distinguish.

Further advantageous embodiments are specified in the subclaims.

In one embodiment of the disc brake, the at least one transducer for structure-borne noise is attached to a structure of the disc brake. This can e.g. a brake carrier, a caliper, or another component.

It is advantageous if the at least one transducer structure-borne sound is attached to the brake caliper of the disc brake, since so the structure-borne noise of the movement of the mechanism of a brake application device is easily detected.

In a further embodiment, the at least one sensor for structure-borne noise is embodied as a structure-borne sound sensor or as an acceleration sensor. Such components are inexpensive available in high quality commercially available.

Alternatively, the at least one transducer for structure-borne noise may be formed as an ultrasonic sensor. Also, this component is advantageous in the market and of high quality.

In another embodiment, two sensors are provided, wherein at least one of the sensors for structure-borne noise as a structure-borne sound sensor or as an acceleration sensor and at least one of the sensors for structure-borne noise can be formed as an ultrasonic sensor. This results in the advantage of increased accuracy and plausibility.

A further embodiment provides that the evaluation unit comprises signal processing and evaluation of the signals supplied by the transducers and passes on suitable information to further control devices and / or display devices. This results in an advantageously compact construction.

In one embodiment of the Lüftspielüberwachungsvorrichtung the at least one sensor for structure-borne noise is designed as a structure-borne noise sensor or as an acceleration sensor. Alternatively, the sensor can also be designed as an ultrasonic sensor. Such components are inexpensive available in high quality commercially available.

Another embodiment of the Lüftspielüberwachungsvorrichtung has a further transducer, wherein at least one of the sensor for structure-borne noise as a structure-borne sound sensor or as an acceleration sensor and at least one of the sensors for structure-borne noise is formed as an ultrasonic sensor. This results in the advantage of a more accurate measurement and a plausibility check.

In addition, it is provided that the evaluation unit comprises signal processing and evaluation of the signals supplied by the transducers and passes on suitable information to further control devices and / or display devices. This is advantageous because it allows a simple evaluation.

In the method, it is provided in a further embodiment that in the second method step S2 Detecting a beginning of the braking operation in the first time is detected by a signal from a brake control unit. In this way, the first time can be detected as the beginning of the braking process without analysis of the structure-borne sound signal. In addition, it is advantageous, as a plausibility is possible.

In yet another embodiment of the method, an immediate indication of a missing clearance occurs with a warning when in the second step S2 Detecting a beginning of a braking operation in the first time detected by a signal from a brake control unit and at the same time no first pulse is detected, or if a grinding of brake pads is determined by an analysis of the structure-borne sound signal in a dissolved state of the brake. This gives the advantage of grinding brake pads or / and blocked wheels immediately detect easily and prevent consequential damage.

If in the second process step S2 Detecting a time measurement between the first time and the second time is done and compared with previously stored time values, advantageously a higher accuracy can be achieved.

• 1 eine schematische Schnittansicht einer erfindungsgemäßen Scheibenbremse;
• 2 schematische grafische Darstellungen von Körperschallsignalen; und
• 3 ein schematisches Flussdiagramm eines erfindungsgemäßen Verfahrens.

The invention will now be described with reference to an exemplary embodiment with reference to the accompanying drawings. Hereby show:

• 1 a schematic sectional view of a disc brake according to the invention;
• 2 schematic graphical representations of structure-borne sound signals; and
• 3 a schematic flow diagram of a method according to the invention.

1 shows a schematic sectional view of a disc brake according to the invention 1 with a clearance monitoring device 6 ,

The disc brake according to the invention 1 includes a brake disc 2 with a brake disk axis of rotation 2a , at least two brake pads 3 . 3 ' , a stationary brake carrier 4 , one adjusting NV , a clamping device ZV and a clearance monitoring device 6 ,

The disc brake according to the invention 1 In contrast to a conventional disc brake, the Lüftspielüberwachungsvorrichtung 6 on. This will be explained below in connection with an exemplary disc brake. One such example of a conventional disc brake is in the document DE 10 2012 108 672 B3 described, which is referred to here.

Therefore, the similarities of the disc brake according to the invention 1 and the usual disc brake only briefly exemplified here, the differences are shown in detail.

The caliper 5 the exemplary disc brake 1 is designed here as a sliding caliper and on the brake carrier 4 slidably mounted attached. The caliper 5 engages over the brake disc 2 and has a clamping section 5a , a back section 5b and two tie rods 5c on.

The brake pads 3 . 3 ' are in the opposite direction in the direction of the brake disc axis of rotation 2a movable. The application device ZV , For example, with a brake rotary lever is in the Zuspannabschnitt 5a the caliper 5 arranged and, for example, pneumatically operated. But it can also be provided another drive, such as a hydraulic and / or electric drive.

The disc brake 1 Here is a two-stamped brake with two threaded punches. On both sides of the brake disc 2 is a brake pad 3 . 3 ' arranged. The brake pad 3 which extends between the application device ZV and the brake disc 2 is, as zuspannseitiger brake pad 3 designated, wherein the brake pad 3 ' on the other side of the brake disc 2 back-side or reaction-side brake pad 3 ' is called.

A distance between the brake pads 3 . 3 ' and the brake disc 2 in the released position of the disc brake 1 , in the 1 is shown is called a clearance.

The adjusting device NV is for wear adjustment of a predetermined clearance, which is referred to as nominal clearance, formed. Here is the adjuster NV connected to one of the two threaded pistons. Structure and function of the adjusting device NV can the document DE 10 2012 108 672 B3 be removed.

A difference of the disc brake according to the invention 1 to the one in the document DE 10 2012 108 672 B3 described disc brake (and others) is that the disc brake according to the invention 1 the clearance monitoring device 6 having.

The clearance monitoring device 6 serves to monitor the clearance of the friction partners brake pads 3 . 3 ' and brake disc 2 , To determine a too large or too small clearance the structure-borne noise is at a suitable point of the disc brake 1 recorded and evaluated by appropriate means. For this purpose, the correct state of the clearance, ie the nominal clearance, is distinguished from the malfunction of a clearance that is too large or too small on the basis of the characteristic structure-borne noise.

The clearance monitoring device 6 includes at least one pickup 7 . 8th . 9 for structure-borne noise and an evaluation unit 10 ,

In the embodiment shown in FIG 1 are three pickups 7 . 8th . 9 provided on the structure of the disc brake 1 are attached at a suitable location. Here are the pickups 7 . 8th . 9 on the caliper 5 arranged. A first pick-up 7 is here on an outside of the Zuspannabschnitts 5a , A second pickup 8th is on one of the tie rods 5c in the area of the brake disc 2 intended. The third pickup 9 is at a transition area between the one tie rod 5c and the back section 5b appropriate.

For mounting the transducer 7 . 8th . 9 can the mounting points, here on the caliper 5 , be especially prepared, eg be provided with suitable flat surfaces. Of course it is also possible that the transducers 7 . 8th . 9 can be used in / screwed into provided for recesses and / or holes.

The transducers 7 . 8th . 9 are designed as structure-borne noise sensors or acceleration sensors. It can be used both passive structure-borne sound sensors that record only the structure-borne sound when the brake is actuated, as well as active sensors that record the reflection of an ultrasonic signal in the dissolved or applied state of the brake or during actuation of the brake. The transducers 7 . 8th . 9 produce an electrical signal corresponding to the structure-borne sound. This signal can be a frequency mixture of different individual signals with different amplitudes. It is also possible that the transducers 7 . 8th . 9 are provided with filters for certain frequencies / frequency range and amplifiers.

The transducers 7 . 8th . 9 are with the evaluation unit 10 via suitable connection lines, which are designed as electrically conductive cable connected.

The evaluation unit 10 includes signal conditioning and evaluation of those from the transducers 7 . 8th . 9 supplied signals and may pass on appropriate information to other control devices. This is the evaluation unit 10 For example, connected to an output unit having certain indicators for warning and monitoring. The evaluation unit 10 may also include a memory device in which all or only certain measured and evaluated signal values are stored and can be read during maintenance / diagnosis.

In 2 are schematic diagrams of structure-borne sound signals 11 . 11a . 11b . 11c . 11d in different states of the disc brake 1 shown.

The structure-borne sound signals 11 . 11a . 11b . 11c . 11d are each simplified as a solid line drawn, each having an amplitude A is plotted over time t.

In the dissolved state of the disc brake 1 that from the moment t0 to t1 runs, is the structure-borne sound signal 11 available and will be from the transducers 7 . 8th . 9 detected.

At a first time t1 An application of the brake by means of the application device begins ZV , For example, with a disc brake 1 a brake rotary lever by a drive cylinder, eg pneumatic cylinder, pivoted against a bridge, whereby the threaded stem against the application-side brake pad 3 be pressed. This is in the document DE 10 2012 108 672 B3 described in more detail and should not be repeated here. As a result, the structure-borne sound signal changes 11 what a momentum 12 with an amplitude A1 is illustrated.

The application process of a correctly functioning brake now runs with a modified structure-borne noise signal 11a with correct clearance until a second time t3 ,

When applying the brake pads 3 . 3 ' at the time t3 to the brake disc 2 arises then by the contact of the brake pads 3 . 3 ' with the brake disc 2 a clearly measurable change in the structure-borne sound signal 11a due to the momentum transfer of the brake pads 3 . 3 ' on the brake disc 2 , This is through an impulse 13 with an amplitude A3 here a greater value than the amplitude A1 owns, represented.

When the brake is applied, another modified structure-borne noise signal is produced 11 b.

If the clearance is too small, the brake pads are applied 3 . 3 ' to the brake disc 2 at an earlier second time t2 as the correct clearance, which here the second time t3 assigned.

In the earlier second time t2 if the clearance is too small, a softened impulse arises 14 with an amplitude A2 whose value is smaller than that of the amplitude A3 of the impulse 13 with correct clearance is. This is done by the evaluation unit through the analysis of the structure-borne sound signal 11a recognized.

In an extreme case of adjacent brake pads 3 . 3 ' on the brake disc 2 in the unconfirmed state (clearance = 0mm) in an unrepresented time between t0 and t1 , the impulse assigned here is missing completely and thus is not in the structure-borne sound signal 11 ascertainable. Here are two cases to distinguish. In a first case, the brake pads grind 3 . 3 ' eg on the brake disc 2 , This can also be done by analyzing the existing structure-borne sound signal in comparison with the structure-borne sound signal 11 be determined in the normal dissolved state of the brake. In a second case, the brake disc 2 through the adjacent brake pads 3 . 3 ' blocked, for example, by a missing structure-borne sound signal and / or other signals, such as a speed sensor of the wheel in question, the disc brake 1 is assigned, is detectable.

Too big a clearance is an impulse 15 in a second, later time t4 in comparison to the intact state of the brake with correct clearance at the time t3 with an amplitude A4 increased, which in turn through a suitable analysis of structure-borne noise 11 can be determined.

In both cases, it is possible to determine the non-existent clearance when a beginning of a braking operation in the first time t1 detected by a signal from a brake control unit and at the same time no first pulse 12 is detected. Then a warning display can be made immediately, which is a non-existent clearance, a grinding of the brake pads 3 . 3 ' and / or a blocked wheel signals.

After a respective impulse 14 (Clearance too small) and impulse 15 (Clearance too high) remains in each case another structure-borne sound signal 11c . 11d ,

In addition, a time signal can be used that measures the duration of the application of the pads to the disc. The application process runs as already stated above from the time t1 until the time t3 with correct clearance.

The starting point t1 also marks a change in the structure-borne sound signal 11 due to the onset of movement of the application mechanism or the brake cylinder, alternatively, a suitable signal from a (not shown) brake control unit. The end point of this time measurement is determined by the respective pulse 12 . 13 . 14 the brake pads 3 . 3 ' on the brake disc 2 and thus in the change of structure-borne sound 11 certainly. If this measured time is too small ( t1 to t2 ) or too big ( t1 to t4 ) compared to the correct clearance when the brake is in an intact state ( t1 to t3 ) and / or the structure-borne sound signal 11 due to the momentum transfer when applying the brake pads 3 . 3 ' to the brake disc 2 too small ( A2 ) or too big ( A4 ) compared to the amplitude A3 if the brake is in good condition when the brake is in good condition, a clearance that is too small or too large is detected.

Possibly. can be further measured variables of a CAN bus of the vehicle, the disc brake 1 is assigned to specify their influence on the time and / or on the structure-borne sound analysis or to perform the evaluation of the clearance only under defined conditions (eg only with cold or warm brake, at certain ambient temperatures, when the vehicle is stationary).

An additional plausibility check can be carried out by an ultrasound signal, which also identifies differences in a faulty clearance compared to a correct clearance. For this example, one of the transducers 7 . 8th . 9 or another transducer or more may be formed as an ultrasonic sensor.

If a detected faulty clearance is detected, the evaluation unit generates 10 a signal which, for example, triggers a warning lamp in the vehicle cockpit or reduces the driving speed by throttling the drive power.

3 shows an exemplary schematic flow diagram of a method according to the invention for operating the Lüftspielüberwachungsvorrichtung 6 ,

In a first process step S1 becomes a structure-borne sound signal 11 by means of transducers) 7, 8, 9 detected on a structure of a brake.

During a braking process at a first time t1 becomes the occurrence of a first pulse 12 in the structure-borne sound signal 11 together with an amplitude of the first pulse 12 in a second process step S2 detected. When a second pulse occurs 13 . 14 . 15 in a second time t2 . t3 . t4 then becomes a respective amplitude A2 . A3 . A4 detected and with a predetermined amplitude A3 a correct clearance compared.

Used in the comparison of the amplitudes A2 . A3 . A4 too small an amplitude A2 determined, it is in a third step S3 a too small clearance displayed and issued a warning. Is too big an amplitude A4 has been recognized, then in the third step S3 A too large clearance displayed and issued a warning. In the case of a correct clearance no warning is given. An ad, eg "clearance in order", can also be made.

In the second process step S2 may be the beginning of the braking process at the time t1 also be detected by a signal from a brake control unit. This can also be done for a plausibility check.

An immediate display of a missing clearance occurs with a warning if in the second step S2 Detecting a beginning of a braking operation in the first time t1 detected by a signal from a brake control unit and at the same time no first pulse 12 is detected, or if by an analysis of the structure-borne sound signal 11 in a dissolved state of the brake grinding of brake pads 3 . 3 ' is detected.

Furthermore, in the second method step S2 a time measurement between the times t1 (Start of braking process) and the time t2 . t3 . t4 the contact of the brake pads 3 . 3 ' on the brake disc 2 and compared with previously stored time values to monitor the clearance. This can also be done for a plausibility check.

In addition, the evaluation unit 10 the structure-borne sound signal 11 . 11a . 11b . 11c . 11d to examine certain frequencies, which further plausibility of each recorded clearance game are possible.

The above-described clearance monitoring device 6 may also be used in disc brakes other than those exemplified. Also use with drum brake is possible.

The invention is to be modified within the scope of the appended claims.

LIST OF REFERENCE NUMBERS

1

disc brake

2

brake disc

2a

brake disc axis

3, 3 '

brake lining

4

brake carrier

5

caliper

5a

Zuspannabschnitt

5b

back section

5c

tension strut

6

Lüftspielüberwachungsvorrichtung

7, 8, 9

pickup

10

evaluation

11, 11a

Borne noise signal

12, 13, 14, 15

pulse

A

amplitude

NV

adjusting

S1-S3

step

t1, t2, t3, t4

time

ZV

application device

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102012108672 B3 [0033, 0039, 0040, 0051]

Claims (16)

Disc brake (1), preferably pneumatically actuated, in particular for a motor vehicle, with a brake caliper (5) engaging over a brake disc (2), two brake linings (3, 3 ') arranged in opposite directions in the caliper (5), an application device (ZV), an adjusting device (NV) and a Lüftspielüberwachungsvorrichtung (6), characterized in that the Lüftspielüberwachungsvorrichtung (6) comprises at least one sensor (7, 8, 9) for structure-borne noise and an evaluation unit (10). Disc brake (1) after Claim 1 , characterized in that the at least one transducer (7, 8, 9) for structure-borne noise is attached to a structure of the disc brake (1). Disc brake (1) after Claim 2 , characterized in that the at least one transducer (7, 8, 9) for structure-borne noise on the caliper (5) of the disc brake (1) is mounted. Disc brake (1) after Claim 2 or 3 , characterized in that the at least one sensor (7, 8, 9) is designed for structure-borne noise as a structure-borne sound sensor or as an acceleration sensor. Disc brake (1) after Claim 2 or 3 , characterized in that the at least one sensor (7, 8, 9) for structure-borne noise is formed as an ultrasonic sensor. Disc brake (1) after one of Claims 1 to 3 , comprising a further transducer (7, 8, 9), characterized in that at least one of the transducer (7, 8, 9) for structure-borne noise as a structure-borne sound sensor or as an acceleration sensor and at least one of the sensors (7, 8, 9) for structure-borne noise than an ultrasonic sensor is formed. Disc brake (1) according to one of the preceding claims, characterized in that the evaluation unit (10) comprises signal processing and evaluation of the signals supplied by the transducers (7, 8, 9) and passes on suitable information to further control devices and / or display devices. Lüftspielüberwachungsvorrichtung (6) for a brake, characterized in that the Lüftspielüberwachungsvorrichtung (6) at least one sensor (7, 8, 9) for structure-borne noise and an evaluation unit (10), wherein the at least one sensor (7, 8, 9) for Structure-borne noise is provided for attachment to a structure of the brake to be assigned. Lüftspielüberwachungsvorrichtung (6) after Claim 8 , characterized in that the at least one sensor (7, 8, 9) is designed for structure-borne noise as a structure-borne sound sensor or as an acceleration sensor. Lüftspielüberwachungsvorrichtung (6) after Claim 9 , characterized in that the at least one sensor (7, 8, 9) for structure-borne noise is formed as an ultrasonic sensor. Lüftspielüberwachungsvorrichtung (6) after Claim 8 , comprising a further transducer (7, 8, 9), characterized in that at least one of the transducer (7, 8, 9) for structure-borne noise as a structure-borne sound sensor or as an acceleration sensor and at least one of the sensors (7, 8, 9) for structure-borne noise than an ultrasonic sensor is formed. Lüftspielüberwachungsvorrichtung (6) according to one of Claims 8 to 11 , characterized in that the evaluation unit (10) comprises signal processing and evaluation of the signals supplied by the transducers (7, 8, 9) and passes on suitable information to further control devices and / or display devices. Method for operating a clearance monitoring device (6) according to one of Claims 8 to 12 on a brake, wherein the Lüftspielüberwachungsvorrichtung (6) at least one sensor (7, 8, 9) for structure-borne noise and an evaluation unit (10), wherein the at least one sensor (7, 8, 9) for structure-borne noise for attachment to a structure of is to be assigned brake, characterized by the method steps S1 detecting a structure-borne sound signal (11) by means of transducer (s) (7, 8, 9) on a structure of a brake; S2 detecting a first pulse (12) in the structure-borne sound signal (11) together with an amplitude (A1) of the first pulse (12) at a first time (t1) and detecting a second pulse (13, 14, 15) having a respective amplitude (A2, A3, A4) at a further time (t2, t3, t4) and comparing with a predetermined amplitude (A3) of a correct clearance; and S3 indicate too small a clearance when the amplitude (A2, A3, A4) is compared with the amplitude (A2) too low, or when the amplitude (A2, A3, A4 ) a too large amplitude (A4) is determined. Method according to Claim 13 , characterized in that in the second method step S2 detecting a beginning of a braking operation in the first time (t1) is detected by a signal from a brake control unit. Method according to Claim 14 , characterized in that an immediate indication of a lack of clearance with a warning occurs when detected in the second method step S2 detecting a beginning of a braking operation in the first time (t1) by a signal from a brake control unit and simultaneously detected no first pulse (12) is, or if by an analysis of the structure-borne sound signal (11) in a dissolved state of the brake, a grinding of brake pads (3, 3 ') is detected. Method according to one of Claims 13 to 15 , characterized in that in the second method step S2 detecting a time measurement between the first time (t1) and the second time (t2, t3, t4) takes place and is compared with previously stored time values.

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