JP5253572B2 - Method and system for monitoring disc brake or drum brake lining clearance - Google Patents

Description

  The present invention relates to a disc brake or drum brake, which also has one or more brake linings, and a method and system for monitoring a lining gap of a brake that is pressurized pneumatically or hydraulically by a brake cylinder. It is. The invention also relates to a computer program product comprising computer program code for carrying out the method according to the invention and to an electronic control device.

  The lining clearance of an automobile disc brake or drum brake, i.e. the clearance between the brake lining and the brake disc or drum disc rotating in conjunction with one of the wheels of the vehicle, depends in particular on the progress of the wear of the brake lining. In order for the brake to function properly, it is important to maintain the lining gap within an appropriate range, usually in the range of about 0.5 to 1 mm. If the lining gap is too large, it takes an unreasonably long time from the start of the braking operation by the driver or the electronic brake control system until the brake is applied, and at the same time there is a risk that the braking effect will be lower than expected. Also, if the lining clearance is too small, there is a risk that inadvertent heat will be generated in the brake, and if it is worse, it may ignite. Large automobiles such as buses, trucks, tractor unit disc brakes or drum brakes are often equipped with automatic lining clearance adjustment devices. However, it is also desirable to be able to monitor the lining gap while driving the vehicle so that, for example, if the lining gap suddenly deviates from the appropriate range, a warning can be issued to the driver.

  The object of the present invention is to provide a new effect of monitoring a lining gap of a brake having a disc brake or a drum brake, which is also provided with one or more brake linings, and is pressurized pneumatically or hydraulically by a brake cylinder. Providing a method and system.

According to the invention, the object is achieved by a method having the features of claim 1 and a system having the features of claim 7.
According to the present invention, the relationship between the stroke of the brake cylinder or the stroke of a certain part of the brake mechanism that transmits the pressure of the brake cylinder to the brake lining and the braking pressure that generates the pressure of the brake cylinder At the time of operation, it is determined based on a measured value representing the stroke and a measured value representing the braking pressure. The position where the brake lining is subjected to the action of the brake cylinder and makes initial contact with the brake disc or the brake drum at each braking operation is determined by gradient analysis of the relationship between the stroke and the braking pressure. The calculated value representing the effective lining clearance is then the difference between the stroke measurement recorded at the determined position and the stroke measurement recorded when the braking pressure is zero. To be determined.

The solution according to the invention has a characteristic that the relationship between the stroke and the braking pressure is significantly different before and after the initial contact of the brake lining with the brake disc or brake drum due to the action of the brake cylinder during braking operation. It uses facts. In order to move the brake lining in the pressurizing direction by a predetermined distance after the initial contact with the brake disc / drum, it is required to significantly increase the braking pressure as compared to before contact. The position at which the brake lining makes initial contact with the brake disc / drum can therefore be determined by analyzing the gradient indicating the relationship between the stroke during braking and the braking pressure. In that case, the movement distance of the brake lining until the brake pressure reaches the initial contact position from the position where the braking pressure is zero matches the lining gap.
The aforementioned braking pressure is a reference for the force applied during braking.

The solution according to the invention provides a simple and reliable way of determining the lining clearance of a disc brake or drum brake. Since the electronically controlled brake system will already have a measurement of the braking pressure of the available brake cylinder, the implementation of the invention in that brake system is particularly easy.
According to one embodiment of the present invention, the calculated value is compared with a predetermined upper limit value, and if the calculated value exceeds the upper limit value, a warning is preferably issued in the form of an audiovisual signal. This allows, for example, the vehicle driver to notice that the lining gap is inappropriately large.
According to another embodiment of the invention, the calculated value is compared with a predetermined lower limit value and if the calculated value falls below this lower limit value, a warning is preferably issued in the form of an audiovisual signal. This allows, for example, the vehicle driver to notice that the lining gap is inappropriately small.

Other advantages of the method and system according to the invention will be apparent from the dependent claims and the following description.
The invention also relates to a computer program product having the features of claim 10 and an electronic control unit having the features of claim 12.
In the following, the invention will be described in more detail on the basis of examples with reference to the accompanying drawings.

1 is a schematic diagram of a system according to one embodiment of the present invention. The diagram which shows the relationship between the stroke of a disc brake or a drum brake, and braking pressure. 1 is a schematic perspective view of a tractor unit including a system according to an embodiment of the present invention. FIG. 1 is a single-line diagram of an electronic control unit for carrying out the method according to the invention. 2 is a flow diagram illustrating the steps of a method according to one embodiment of the invention.

  FIG. 1 is a schematic diagram of a system 1 according to an embodiment of the present invention for monitoring a lining clearance of a disc brake 10, which includes brake linings 11 a and 11 b and pneumatic brake pressure is applied by a brake cylinder 12. It is done. In the illustrated example, the disc brake 10 is a conventional automotive wheel brake that includes a brake disc 13 coupled to a vehicle wheel for rotation with the wheel, and is therefore adapted to rotate with the wheel. ing. On each side surface of the brake disk 13, friction surfaces 14a and 14b are provided.

  The disc brake includes an outer brake block 15a disposed on one side of the brake disc 13, the outer brake block having one or more brake linings 11a on the side facing the brake disc. The disc brake further includes an inner brake block 15b disposed on the other side of the brake disc 13, the inner brake block having one or more brake linings 11b on the side facing the brake disc. The brake blocks 15a and 15b are moved in the direction of the brake disk 13 so as to respond to the braking operation, and the brake linings 11a and 11b are frictionally engaged with the friction surfaces 14a and 14b. Brakes the rotation of the wheel coupled to.

  In the case of the embodiment of FIG. 1, the brake includes a brake mechanism 16 adapted to transmit the pressing force of the brake cylinder 12 to the brake blocks 15a, 15b and thus to the brake linings 11a, 11b. The brake mechanism 16 is disposed in the brake yoke 17 together with the brake blocks 15a and 15b, and is supported so as to linearly move in the brake yoke, and a lever arm 18 supported to pivot in the brake yoke. It includes an adjustment member 19 and one or more pistons 20 supported for linear motion within the brake yoke. The brake yoke 17 itself is capable of linear motion with respect to the brake cylinder 12 and the brake disc 13 perpendicular to the friction surfaces 14 a, 14 b of the brake disc 13. The adjusting member 19 is configured to automatically adjust the brake lining clearance, that is, the clearance between the brake linings 11a and 11b and the brake disc 13 in a conventional manner.

  In the illustrated embodiment, the brake cylinder 12 includes a push rod 21, a return spring 22, a chamber, and a membrane 24 that divides the chamber into a first portion 23a and a second portion 23b. The second part 23b of the chamber is connected to a compressed air source 9 via a compressed air line 2, and the supply of compressed air to this part of the chamber is controlled by a regulating valve 3 provided in the compressed air line. . The push rod 21 is fixed to the membrane 24 so as to act on one end of the lever arm 18. The push rod 21 is movable in the direction of the lever arm 18 against the action of the return spring 22 disposed inside the brake cylinder. When the braking operation is commanded by the driver of the vehicle, for example, via the brake lever 4, the adjustment valve 3 is opened, so that compressed air flows into the second portion 23b of the chamber.

  As a result, the pneumatic braking pressure generated in the second portion 23 b of the chamber is converted into a pressing force acting on the lever arm 18 by the membrane 24 and the push rod 21. When this pressing force becomes sufficiently large, the push rod 21 is moved toward the lever arm 18 against the action of the return spring 22. As a result, the lever arm 18 pivots, and not only the pressing force pressing the inner brake block 15b against the brake disc 13 is applied to the inner brake block 15b via the adjusting member 19 and the piston 20, but also the brake yoke 17 is applied. The force in the opposite direction is also applied. This force generates a pressing force through the sliding bearing of the brake yoke, and this pressing force acts on the outer brake block 15a to press the brake block toward the brake disc 13.

  When braking, the brake blocks 15a and 15b first receive the action of the brake cylinder 12 and move in the direction of the brake disk 13 to the position where the brake linings 11a and 11b initially contact the friction surfaces 14a and 14b of the brake disk 13. . This initial movement corresponds to the lining gap and is usually about 0.5-1 mm. After the brake linings 11a and 11b initially contact the friction surfaces 14a and 14b of the brake disc, the brake blocks 15a and 15b further move toward the brake disc 13 due to the action of the brake cylinder 12. As a result, the frictional force between the brake linings 11a and 11b and the friction surfaces 14a and 14b of the brake disk increases to a level at which the target braking effect can be achieved.

FIG. 2 shows a movement s of a brake cylinder push rod 21 or a part of a brake mechanism mechanically coupled to the push rod and operated by the push rod, and the number of brake cylinder chambers for generating the brake cylinder pressing force. It is a diagram which shows the relationship at the time of braking operation with the air pressure p in 2 part 23b. In the present specification and claims, this movement s is referred to as “stroke” and the pressure p is referred to as “braking pressure”. FIG. 2 clearly shows that the curve 25 representing the relationship between the stroke s and the braking pressure p is before and after the initial contact position s ₁ of the brake lining 11a, 11b with the friction surfaces 14a, 14b of the brake disc 13. It shows that it has a different slope. Therefore, by analyzing the gradient indicating the relationship between the stroke s and the braking pressure p, the position s ₁ where the brake lining is initially brought into contact with the brake disc by the action of the brake cylinder can be determined. The moving distance from the position s ₀ where the braking pressure p is zero to the initial contact position s ₁ corresponds to the lining gap.

  The measured value Vp representing the braking pressure p is detected by a pressure sensor 5, which in the illustrated embodiment is adapted to detect the pressure in the compressed air line 2 between the regulating valve 3 and the brake cylinder 12. ing. The measured value Vs representing the stroke s is detected by a sensor 6, which in the illustrated embodiment is adapted to detect the movement of the piston 20. The sensor used for detecting the stroke s may alternatively detect movement of some other part of the brake mechanism 16 or movement of the push rod 21 of the brake cylinder.

  In the illustrated embodiment, the system 1 according to the invention is adapted to cooperate with an electronic braking system, whereby the regulating valve 3 detects the actuating movement of the brake lever 4 operated by the driver of the vehicle. It is controlled by the electronic control unit 7 on the basis of the measured value from the sensor 8 configured to do so. The control unit 7 is also adapted to receive information from the pressure sensor 5 relating to the braking pressure p. In that case, the measured value Vp representing the braking pressure p is also obtained from the control unit 7. Alternatively, the regulating valve 3, and thus the braking pressure p, is directly controlled by the brake lever, in which case the measured value Vp representing the braking pressure p is determined based on the position of the brake lever.

The system 1 according to the present invention includes a processing device 31, which
-During braking operation, the relationship between the stroke s and the braking pressure p is determined based on the measured value Vs representing the stroke and the measured value Vp representing the braking pressure, and-the stroke s and the braking pressure p The brake linings 11a and 11b receive the action of the brake cylinder 12 to determine the position where the brake lining 11a and 11b make initial contact with the brake disc 13 during each braking operation. Further, the difference between the measured value Vs ₁ of the stroke s recorded at the detection position and the measured value Vs ₀ of the stroke s recorded when the braking pressure p is zero To be determined based on.

  Although the processing device 31 can be realized by the control unit 7 described above, in the illustrated embodiment, the processing device 31 is realized by another electronic control unit 30. The electronic control unit 30 receives the measurement value Vp representing the braking pressure p from the unit 7 by being connected to the control unit 7 mentioned at the beginning, and the measurement value representing the stroke s from the sensor 6 by being connected to the sensor 6. Receive Vs.

  The processing device 31 compares the determined calculated value BV with a predetermined upper limit value GV1 representing a value that the lining clearance should not exceed. If the calculated value BV exceeds the upper limit value GV1, the processing device 31 warns the driver of the vehicle. It is supposed to be emitted. The processing device 31 also compares the determined calculated value BV with a predetermined lower limit value GV2 representing a value that the lining gap should not fall below, and warns the vehicle driver if the calculated value BV falls below the lower limit value GV2. To be emitted. This warning is presented, for example, in the form of an audible signal and / or a viewing angle signal, for example via a display unit in the vehicle cab or some other warning indicator.

  FIG. 3 shows a vehicle 40 in the form of a tractor unit. The tractor unit includes a conventional drum brake 110 that operates with pneumatic braking pressure applied by a brake cylinder 112. Each drum brake 110 includes a brake drum 113 that is coupled to a vehicle wheel to rotate simultaneously with the wheel, and is thus adapted to rotate with the wheel. A friction surface is provided inside the brake drum. The drum brake 110 further includes two brake blocks 115a and 115b. These brake blocks are disposed inside the brake drum 113, and each has brake linings 111a and 111b on the side facing the brake drum. The brake linings 111a and 111b are frictionally engaged with the friction surface of the brake drum in response to the brake being applied by moving outward toward the brake drum 113, so that the brake blocks 115a and 115b The rotation of the drum, and hence the rotation of the wheel 100 coupled to the brake drum, is braked.

  In the case of the embodiment shown in FIG. 3, the brake includes a brake mechanism 116 adapted to transmit the pressing force applied by the brake cylinder 112 to the brake blocks 115a and 115b and consequently to the brake linings 111a and 111b. This brake mechanism has an adjusting device 119 and a cam shaft 117. The adjusting device 119 is configured to automatically adjust the brake lining clearance, that is, the clearance between the brake linings 111a and 111b and the brake drum 113 in a conventional manner. The configuration and function of the brake cylinder 112 are similar to the configuration and function of the brake cylinder already described in FIG. The brake cylinder 112 includes in particular a push rod that is adapted to act on the adjusting device 119 and also allows linear movement in the direction of the adjusting device against the action of a return spring arranged inside the brake cylinder. is there.

  The adjusting device 119 is also adapted to convert the linear movement of the push rod as a lever arm into a rotating movement of the camshaft 117 in addition to the adjusting function. For example, when the driver of the vehicle orders a braking operation via the brake lever, the compressed air flows into the chamber of the brake cylinder 112. Thereby, the air braking pressure generated in the chamber is converted into a pressing force acting against the adjusting device 119 via the membrane in the brake cylinder and the push rod. When this pressing force becomes sufficiently large, the push rod is moved in the direction of the adjusting device 119 against the action of the return spring. The adjusting device 119 is thereby pivoted and causes the camshaft 117 to rotate, the camshaft itself pressing the brake blocks 115a, 115b outwardly via a control cam arranged on the camshaft, The brake block is pressed against the brake drum 113.

  When the brake is applied, the brake blocks 115a and 115b first receive the action of the brake cylinder 112 and move toward the brake drum to a position where the brake linings 111a and 111b initially contact the friction surface of the brake drum. This initial movement corresponds to the lining gap. After the brake linings 111a and 111b make initial contact with the friction surface of the brake drum, the brake blocks 115a and 115b are further moved toward the brake drum 113 by the action of the brake cylinder 112, so that the brake linings 111a and 111b The frictional force with the friction surface of the brake drum increases to a level where a desired braking effect can be obtained. According to the present invention, the lining clearance of the drum brake 110 is determined in a format corresponding to the above-described format.

  The method and system according to the present invention could also be used to monitor the disc brake or drum brake lining clearance that is hydraulically applied by a brake cylinder. In that case, the aforementioned braking pressure p will constitute the hydraulic pressure in the brake cylinder that generates the pressing force of the brake cylinder.

FIG. 5 is a flow diagram illustrating one embodiment of the method of the present invention for monitoring the lining clearance of a disc brake or drum brake, the brake including one or more brake linings, and pneumatic or fluid by brake cylinders 12,112. The braking pressure can be applied in a pressure manner. In the first stage S1, that is, in the initial braking operation, the stroke of the brake cylinders 12, 112 or the stroke of a part of the brake mechanism 16, 116 adapted to transmit the pressing force of the brake cylinder to the brake lining, and the brake cylinders 12, 112 Is determined based on the measured value Vs representing the stroke and the measured value Vp representing the braking pressure. In the second step S2, the gradient indicating the relationship between the stroke and the braking pressure is analyzed, and the linings 11a, 11b, 111a, and 111b receive the action of the brake cylinders 12 and 112 during each braking operation, and the brake disc 13 Alternatively, the initial contact position with the brake drum 113 is determined. Then, in the third step S3, the calculated value BV which represents a valid lining clearance, the measured values Vs ₁ of the recorded the stroke at the determined said positions, the brake pressure is recorded at zero of the stroke It is determined based on the difference between the measured value Vs _0.

  The computer program code for carrying out the method according to the invention is preferably contained in a computer program that can be read into an internal memory of a computer, for example an internal memory of an electronic control system of a motor vehicle. This computer program is preferably obtained via a computer program product including a data storage medium, which is readable by an electronic control unit, in which the computer program is stored. The data storage medium is, for example, an optical data storage medium in the form of a CD ROM disk, a DVD disk, etc., or a magnetic data storage medium in the form of a hard disk, diskette, cassette tape, or the like, or ROM, PROM, EPROM, EEPROM, etc. A type of memory, or flash memory.

A computer program according to one embodiment of the invention is an electronic vehicle having a disc brake or drum brake, which also has one or more brake linings, and has a brake to which pneumatic or hydraulic braking pressure is applied by a brake cylinder. The control unit performs the following tasks:
The operation of determining or receiving the measured value Vs representing the stroke of the brake cylinder or the stroke of a part of the brake mechanism adapted to transmit the pressing force by the brake cylinder to the brake lining;
The operation of determining or receiving a measured value Vp representing the braking pressure that generates the pressing force of the brake cylinder;
-Work for determining the relationship between the stroke and the braking pressure during braking operation based on the measured values Vs, Vp;
The work of determining the position where the brake lining makes initial contact with the brake disc or brake drum during each braking operation under the action of the brake cylinder by analyzing the gradient indicating the relationship between the stroke and the braking pressure;
The calculated value BV representing the effective lining clearance is the difference between the stroke measurement value Vs ₁ recorded at the determined position and the stroke measurement value Vs ₀ recorded when the braking pressure is zero; Work to decide on the basis of,
Includes computer program code for implementing

  FIG. 4 is a schematic diagram of an electronic control unit 30 including execution means 34 for computer software execution, for example, a central processing unit (CPU). The execution means 34 communicates with a memory 36, for example, a RAM type memory via a data bus 35. The control unit 33 also includes a data storage medium 37 in the form of a ROM, PROM, EPROM, EEPROM type memory or flash memory, for example. Execution means 34 communicates with data storage medium 37 via data bus 35. A computer program comprising computer program code for carrying out the method according to the invention, for example the method according to the embodiment shown in FIG.

The invention is particularly intended for use in large vehicles such as buses, tractor units, trucks.
Needless to say, the present invention is not limited to the embodiments described above. It will be apparent to those skilled in the art that many modifications can be made to the present invention without departing from the basic concept of the invention as defined in the claims.

Claims (12)

A lining gap of a disc brake or a drum brake (10; 110) provided with one or more brake linings (11a, 11b; 111a, 111b) and applied with pneumatic or hydraulic braking pressure by a brake cylinder (12: 112) In the method of monitoring
The stroke of the brake cylinder (12: 112) or the stroke of a part of the brake mechanism (16; 116) adapted to transmit the pressing force by the brake cylinder to the brake lining, and the pressing force of the brake cylinder; A relationship between the braking pressure to be created is determined based on a measured value (Vs) representing the stroke and a measured value (Vp) representing the braking pressure during a braking operation;
-The position where the brake lining (11a, 11b; 111a, 111b) initially contacts the brake disc or the brake drum during each braking operation is affected by the operation of the brake cylinder (12: 112). Being determined by an analysis of the gradient indicating the relationship with the braking pressure;
A calculated value (BV) representing the effective lining gap is a measured value (Vs ₁ ) of the stroke recorded at the determined position and a measured value of the stroke recorded when the braking pressure is zero; Being determined based on the difference from (Vs ₀ );
A method for monitoring the lining clearance of a disc brake or drum brake characterized by   Method according to claim 1, characterized in that the braking pressure is adjusted by the electronic control unit (7), characterized in that a measured value (VP) representing the braking pressure is obtained by the electronic control unit (7).   2. The braking pressure is adjusted via the brake lever (4), characterized in that the measured value (Vp) representing the braking pressure is determined by detecting the position of the brake lever (4). The method described.   A measured value (Vs) representing the stroke is determined by a sensor (6) adapted to detect the position of a push rod (21) of the brake cylinder or a part of the brake mechanism (16; 116). 4. A method according to any one of claims 1 to 3, characterized in that:   The calculated value (BV) is compared with a predetermined upper limit value (GV1) and if the calculated value (BV) exceeds the upper limit value (GV1), a warning is preferably issued in the form of an auditory or visual signal 5. A method according to any one of claims 1 to 4, characterized in that.   The calculated value (BV) is compared with a predetermined lower limit value (GV2) and if the calculated value (BV) falls below the lower limit value (GV2), a warning is preferably issued in the form of an auditory or visual signal 6. A method according to any one of claims 1 to 5, characterized in that In a system with one or more brake linings, and also for monitoring the lining clearance of a disc brake or drum brake to which pneumatic or hydraulic braking pressure is applied by a brake cylinder,
The system (1) includes a processing device (31), and the processing device includes:
The stroke of the brake cylinder or the stroke of a part of the brake mechanism adapted to transmit the pressing force by the brake cylinder to the brake lining during the braking operation, and the braking pressure that generates the pressing force of the brake cylinder; The relationship is determined on the basis of a measured value (Vs) representing the stroke and a measured value (Vp) representing the braking pressure, and-during each braking operation, The position at which the brake lining makes initial contact with the brake disc or the brake drum is determined by analyzing the gradient indicating the relationship between the stroke and the braking pressure, and further-a calculated value representing an effective lining clearance (BV) when the measured value (Vs ₁ ) of the stroke recorded at the determined position and the braking pressure is zero A system for monitoring a lining gap of a disc brake or a drum brake, which is determined based on a difference from the measured value (Vs ₀ ) of the stroke recorded in the above.   The processing device (31) compares the calculated value (BV) with a predetermined upper limit value (GV1), and generates a warning when the calculated value (BV) exceeds the upper limit value (GV1). The system of claim 7.   The processor (31) compares the calculated value (BV) with a predetermined lower limit value (GV2), and generates a warning when the calculated value (BV) falls below the lower limit value (GV2). The system according to claim 7 or claim 8. In a computer program product comprising computer program code, an electronic control unit for an automobile comprising a disc brake or drum brake with one or more brake linings and applied with pneumatic or hydraulic braking pressure by a brake cylinder,
Determining or receiving a measurement value (Vs) representative of a stroke of the brake cylinder or a stroke of a part of a brake mechanism adapted to transmit the pressing force by the brake cylinder to the brake lining; Determining or receiving a measurement value (Vp) representative of the braking pressure that produces a pressing force of the brake cylinder;
The relationship between the stroke and the braking pressure during braking operation is determined based on the measured values (Vs, Vp);
Analyzing the gradient indicating the relationship between the stroke and the braking pressure to determine the position at which the brake lining is initially brought into contact with the brake disc or brake drum under the action of the brake cylinder during each braking operation; To be and
A calculated value (BV) representing an effective lining clearance is obtained by measuring the stroke measured value (Vs ₁ ) recorded at the determined position and the stroke measured value recorded when the braking pressure is zero ( Vs ₀ ) and a computer program product comprising computer program code that is adapted to be determined based on the difference between the two.   11. The computer program product of claim 10, wherein the computer program product includes a data storage medium readable by an electronic control unit, and wherein the computer program code is stored on the data storage medium.   11. The electronic control unit of an automobile, comprising an execution device (34), a memory (36) connected to the execution device, and a data storage medium (37) connected to the execution device. An electronic control unit for a motor vehicle in which computer program code of a computer program product is stored in the data storage medium (37).

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