WO2020057972A1

WO2020057972A1 - Method for transferring signals from sensors of a vehicle brake, and vehicle brake having a sensor arrangement

Info

Publication number: WO2020057972A1
Application number: PCT/EP2019/073533
Authority: WO
Inventors: Alexander Fuchs; Bence SZEMES; Tamas KONYA
Original assignee: Knorr-Bremse Systeme für Nutzfahrzeuge GmbH
Priority date: 2018-09-18
Filing date: 2019-09-04
Publication date: 2020-03-26
Also published as: DE102018122881A1

Abstract

The invention relates to a method for transferring signals (112, 122, 132) from at least two sensors (11-13) of a vehicle brake (1). The method has the following steps: A first signal (112) from a first of the sensors (11-13) is provided at a signal output (141) in a first transfer section (113), and then a second signal (122) from a second of the sensors (11-13) is provided at the signal output (141) in a second transfer section (123). The invention further relates to a vehicle brake (1) having a sensor arrangement (10) with at least two sensors (11-13), which arrangement is distinguished in that outputs (111, 121, 131) of the sensors (11-13) are connected to inputs (142) of a multiplexer (14), via which they can be connected successively to a signal output (141) of the sensor arrangement (10).

Description

DESCRIPTION

Method for transmitting sensor signals from sensors

Vehicle brake and vehicle brake with a sensor arrangement

The invention relates to a method for transmitting sensor signals from

at least two sensors of a vehicle brake. The invention further relates to a vehicle brake with a sensor arrangement with at least two sensors.

Brakes in commercial vehicles often have a wear sensor that outputs a wear value for the brake pads of the brake. The signal can be a continuous, usually analog signal, a measured one

Shows the degree of wear. In addition, discrete-working systems are known which generally only signal an end wear value, that is to say record and output a maximum permissible wear of the brake lining. Such a signal is a

Warm signal for the driver to have the brake pads replaced immediately. The systems that output a continuous wear value for the degree of wear not only enable the end wear value to be recognized, but also advantageously enable preventive or predictive maintenance control. This saves costs for visits to the workshop and reduces downtimes.

In both cases, a standardized analog signal line is usually used to transmit the recorded wear values to a higher-level vehicle electronics. This analog signal line is standardized e.g. with regard to the voltage range within which the signals emitted by the sensors lie.

So far, only discreetly operating wear sensors have generally been used in vehicle trailers or semitrailers, with the sensor signals of several brakes possibly being interconnected to form a signal such that a

Wear of each brake can be signaled, but no information is available on the higher-level vehicle electronics which of the brakes is worn down to the maximum degree of wear. For this, several such can be discreet working sensors can be connected to a common signal line. In the case of continuously operating sensors, such a connection of the sensors on a signal line is not possible in this way.

Due to the advantages in terms of costs and a reduction in downtimes, concepts that enable preventive or predictive maintenance control are increasingly being implemented. This includes, for example, the use of continuously working sensors on the brakes of commercial vehicle trailers or semi-trailers. The use of several sensors on one brake, for example to determine the wear value of both brake pads of a brake independently of one another

to be able to record continuously, or to add further brake parameters,

For example, being able to measure temperature is helpful in order to identify emerging problems at an early stage and to be able to carry out specific maintenance before these problems lead to a failure of the vehicle. However, with the number of sensors, in particular the number of sensors that output a continuous analog signal, the number of lines required to the higher one increases

Vehicle electronics, which in addition to increased effort in the vehicle

is particularly problematic for retrofit solutions. For reasons of compatibility, it is desirable, even when using several sensors, to the known and

to be able to use standardized signal transmission via an analog signal in the specified range.

It is therefore an object of the present invention to provide a vehicle brake with a sensor arrangement with at least two sensors and a method for transmitting sensor signals from sensors of a vehicle brake, in which a simply available analog signal line can be used to transmit the sensor signals.

This object is achieved by a vehicle brake or a transmission method with the features of the respective independent claim. Advantageous refinements and developments are specified in the dependent claims. A method according to the invention of the type mentioned at the outset has the following steps: a first sensor signal from a first of the sensors is provided at a signal output in a first transmission section and then a second sensor signal from a second of the sensors at the signal output in a second transmission section.

The sensor signals are thus transmitted in succession in a time-division multiplexing process over one and the same signal line. In this way, the signals of several sensors can be transmitted via a standard signal line.

In an advantageous embodiment of the method, each transmission section is preceded by an identification section in which an identification signal is output at the signal output which is suitable for identifying the sensor whose sensor signal is subsequently output. In this way it can be ensured that a receiver of the output signal, e.g. within central vehicle electronics that can correctly assign the transmitted signals to the sensors used. The identification signal is preferably at least temporarily outside a voltage range which is defined for the sensor signals. The

Identification signal can have, for example, a predetermined voltage in the identification section, on the basis of which the assignment takes place. The use of voltages that lie outside the (output) voltage range that is defined for the sensors allows the identification signal to be clearly identified and prevents it from being confused with a sensor signal.

In a further advantageous embodiment of the method, one comprises

Transmission sequence the successive provision of a predetermined number of transmission sections and identification sections. One is preferred

Transmission sequence is started when at least one of the sensor signals meets a predetermined criterion. In this way, event-related transmission of the signals can be initiated. As an alternative or in addition, provision can also be made for a transmission sequence to be external, for example from the central vehicle electronics is requested. Alternatively, a permanent repetition of the

Transmission sequence, e.g. at predetermined intervals. Within a transmission sequence, for at least one of the

Transmission sections can be specified for a fixed period of time. Different time periods can be specified for different transmission sections.

A vehicle brake according to the invention of the type mentioned at the outset is characterized in that outputs of the sensors have inputs of a multiplexer

are connected, via which they are successively connected to a signal output of the

Sensor arrangement are connectable. The method described above can be easily implemented with such a sensor arrangement. The advantages mentioned in connection with the method result.

In an advantageous embodiment of the vehicle brake, the sensor arrangement has a microcontroller which is connected to control inputs of the multiplexer

Control is coupled. The required control of the multiplexers for implementing the time structure can be flexibly implemented via a microcontroller.

In an advantageous embodiment of the vehicle brake, at least one input of the microcontroller is connected to at least one of the outputs of the sensors. The microcontroller is preferably set up to monitor the at least one of the outputs in order to start a transmission sequence of sensor signals of at least two sensors. In this embodiment, the

Microcontrollers are used to start a transmission sequence event-controlled depending on one or more of the signals.

The invention is explained in more detail below on the basis of exemplary embodiments with the aid of figures. The figures show:

Fig. 1 a is a schematic plan view of a brake of a vehicle with a

Sensor arrangement;

1 b shows a block diagram of a sensor arrangement; and 2, 3 each show a schematic representation of a time dependence of

Sensor signals and an output signal of a sensor arrangement according to the application.

1 a schematically shows a vehicle brake 1, in particular one

Commercial vehicle brake, which is also referred to below simply as brake 1.

The brake 1 has a brake caliper 3 which is floatingly supported on a brake carrier 2. An actuator 4 is arranged on the brake caliper 3; a pneumatic actuator is shown by way of example.

The brake 1 shown is a disc brake which acts on a brake disc 6 with two brake pads 5. One of the brake pads 5, in Fig. 1 a that shown on the left side, is firmly positioned in the brake caliper 3, whereas the other brake pad 5, which is shown on the right side in Fig. 1 a, by the actuator 4 against the brake disc 6 is pressed. The basic principle of a brake with sensor unit described in this application can be transferred to types of brakes other than those shown and also to brakes with pneumatic actuators 4 other than those shown.

The brake 1 is equipped with a sensor arrangement 10 which comprises at least two sensors with which physical parameters in the area of the brake 1 are detected. 1 b, the sensor arrangement 10 is shown in more detail in the form of a block diagram.

In the example shown, the sensor arrangement 10 comprises three sensors 11, 12, 13. These sensors can, for example, be force sensors with which the application of the brake 1 and thus the correct function of the actuator 4 can be monitored. Furthermore, one or more of the sensors 11 -13 can be wear sensors which detect a degree of wear of one or both brake linings 5. Furthermore, one of the sensors 11 -13 can be a temperature sensor, for example, in order to determine a temperature, for example of the brake caliper 3 or of a brake lining 5. The number of three sensors in the sensor arrangement 10 shown in FIG. 1 b is purely exemplary. According to the application, at least two sensors are provided, but the number of sensors can also be greater than the three sensors shown.

The sensors 11-13 each have an output 111, 121 or 131, at which an output signal of the respective sensor 11 -13 is output as an analog voltage signal within a predetermined voltage range. The outputs 111, 121, 131 of the sensors 11 -13 are coupled to inputs 142 of a multiplexer 14. An output of the multiplexer 14, which can be selectively controlled connected to one of the inputs, also represents the signal output 141 of the sensor arrangement 10.

The multiplexer 14 is controlled via control inputs 143, via which it is selected which of the inputs 142 is forwarded to the signal output 141. The inputs 143 are controlled via switching outputs 151 of a microcontroller 15. The microcontroller 15 further comprises inputs 152, these are preferred

Analog inputs that are connected to at least one output 111-113 of at least one sensor 11-13. In the present case, the microcontroller 15 has three inputs 152, one of the inputs 152 being connected to one of the sensors 11-13. It is also conceivable that only one of the sensors 11-13 is then coupled to the microcontroller 15 via only one input 152. In addition, an output, in the present case an analog output 153, of the microcontroller 15 is connected to a further one of the inputs 142 of the multiplexer 14. A signal generated by the microcontroller 15 can be output on the signal output 141 via the analog output 153 and the assigned input 142.

The mode of operation of the sensor arrangement 10 is explained in FIGS. 2 and 3 for two different configurations of the sensor arrangement 10 on the basis of exemplary signal profiles of output signals from the sensors 11-13.

According to the application, a transmission of several sensor signals 112, 122, 132 of the sensors 11 -13 is achieved in that the outputs 111, 121, 131 of the sensors 11 -13 are successively during a transmission sequence 22 (see FIG. 2) with the aid of the

Multiplexers 14 placed on the analog output 141 of the sensor device 10 become. With a transmission via a standardized analog signal line, it can be achieved that the analog output signals 112, 122, 132 of the plurality of sensors 11 -13 can be transmitted.

2 shows this procedure using a first example. A time dependence of the sensor signals 112, 122, 132, which are present at the outputs 111, 121, 131 of the sensors 11-13, is shown in the form of a diagram. The sensor signals 112, 122, 132 are represented by differently dotted or dashed curves in the diagram. On the horizontal axis of the diagram, a time t is shown in arbitrary units (a.u. - arbitrary units). A respective output voltage U is likewise indicated in arbitrary units on the vertical axis. in the

A predetermined voltage range 21 is also shown in the diagram, within which the sensor signals are expected. The appearance of a

Output voltage of a sensor 11 -13 or also the sensor arrangement 10 is interpreted by a receiving unit as an error signal or as a control signal.

The curve profiles of the sensor signals 112, 122, 132 shown in the diagram are purely exemplary. In the illustrated case, the first sensor 11 is a force sensor, which detects an application force of the actuator 4. The second sensor 2 can be a wear sensor, for example, and the third sensor 3 can measure a temperature.

In the example shown, a transmission sequence is started when a significant increase in the signal 112 of the first sensor 11 is observed. First of all, the multiplexer 14 is controlled by the microcontroller 15 such that the sensor signal 112 of the first sensor 11 is present at the output 141. One at exit 141

Output signal 142 is highlighted in FIG. 2 by a solid line. The solid line is therefore initially congruent with the dotted curve of the sensor signal 112 of the first sensor 11. The time range in which the sensor signal 112 of the first sensor 11 is output is identified in FIG. 2 as the first transmission section 113.

In the example shown, the brake 1 is actuated within this transmission section 113, which is reflected in the steep rise in the sensor signal 112 shown Sensor 11 and thus also reflected in the output signal 142. This increase is detected by the microcontroller 15 via the corresponding input 152, whereupon the transmission sequence 22 is started at a start time ts.

It goes without saying that a changing signal from one of the other sensors, that is to say the second sensor 12 and / or the third sensor 13, can also function as the start signal (trigger). It is also conceivable to request a transmission sequence 22 externally, for example via a separate control line or by applying a certain potential to the output 141 of the multiplexer, this signal being able to be detected accordingly via a further input of the microcontroller 15. In this case, the multiplexer 14 is to be structurally designed such that it tolerates the application of a specific voltage signal to its output 141 without damage.

It is provided within the transmission sequence 22 that the signal 112 of the first sensor 11 is still present at the output 141 for a predefined time.

This is followed by an identification section which announces that the multiplexer 14 now switches the output 141 to the sensor signal 122 of the second sensor 12. The identification section is referred to below as the second identification section 124 because it is upstream of a second transmission section 123. In this second transmission section 123, the output 141 accordingly

Transmit sensor signal 122 of the second sensor 2. The period for which this happens can be set individually and does not have to correspond to the period of time that the first transmission section 113 continues after the

Transmission sequence 22 is started.

After the completion of the second transmission section 123 there follows again an identification section, hereinafter referred to as the third identification section 134, which announces a following third transmission section 133, in which the

Sensor signal 132 of the third sensor 13 is output at the output 141. After the third transmission section 133 has ended, another one follows

Identification section, which is called the first identification section 114 and which is connected upstream of a further first transmission section 113, in which - again at the beginning - the sensor signal 112 of the first sensor 11 is output. The transmission sequence 22 ends when the first sensor signal 112 is transmitted again at a time te.

Through the identification sections 114, 124 and 134 a recipient of the

Output signal 141 transmitted which of the signals 112, 122, 132 is transmitted next. The identification sections 114, 124, 134 thus ensure that the output signal 141 on the receiver side, e.g. in a central

Vehicle electronics, is correctly identified.

For example, in the illustrated case, a voltage outside the predetermined voltage range 21 is assumed within an identification section 114, 124, 134, so that the signal in the identification sections 114, 124, 134 can be distinguished from a sensor signal. It is noted that other voltage sequences within an identification section 114, 124, 134 for

Identification can be used. For example, a pulse sequence can be transmitted within the identification sections 114, 124, 134, in which the number of the sensor to be subsequently transmitted is coded. In the example shown, the fleas of the voltage within the respective identification section 114, 124, 134 are used for identification. The signal can be generated in the identification sections 114, 124, 134 e.g. by the microcontroller 15 at its analog output 153. By appropriate activation of the multiplexer 14, the signal is then switched to the signal output 141 in the identification sections 114, 124, 134.

FIG. 3 shows another example of a time profile of sensor signals 112, 122 and output signal 142 in the same way as FIG. 2. Reference is hereby made to the description of FIG. 2 and the underlying arrangement according to FIGS. 1 and 1b.

In the example of FIG. 3, the sensor arrangement 10 is designed for three sensors 11-13, as shown in FIG. 1b, but is only equipped with two sensors 11 and 12. For this reason, within the transmission sequence 22, in the third transmission section 133, in which the signal 132 is agreed and as expected of the third sensor 13 would be transmitted, a signal is faded in, which changes in rapid succession between voltage values below and above the predetermined voltage range 21 and which is accordingly identified by a receiving unit as an impermissible signal.

The signal is generated by the sensor arrangement 10 in the microcontroller 15 and is input into the multiplexer 14 instead of the signal 131 of the sensor 13 via the corresponding connection 152 of the microcontroller. This is possible if the inputs 152 of the microcontroller 15 described in connection with FIG. 1b are designed bidirectionally and can also be used as outputs by the microcontroller 15. For this purpose, the microcontroller 15 can detect the missing signal 131 of the sensor 13 not present in an initialization phase and generate the error signal visible in FIG. 3. Alternatively, the analog output 153 of the

Microcontrollers 15 are used to output the signal mentioned, which signals a sensor that is not present, and to switch it to the signal output 141 via the multiplexer 14.

REFERENCES

1 vehicle brake

2 brake carriers

3 brake calipers

4 actuator

5 brake pad

6 brake disc

10 sensor arrangement

11 first sensor

111 Output of the first sensor

112 Sensor signal of the first sensor

113 first transmission section

114 first identification section

12 second sensor

121 Output of the second sensor

122 sensor signal of the second sensor

123 second transmission section

124 second identification section

13 third sensor

131 Output of the third sensor

132 sensor signal of the third sensor

133 third transmission section

134 third identification section

14 multiplexers

141 Multiplexer output

142 Input of the multiplexer

143 Control input of the multiplexer

15 microcontrollers

151 Control output of the microcontroller

152 Analog input of the microcontroller 153 Analog output of the microcontroller

21 defined voltage range

22 Transmission sequence ts start time

te end time

Claims

PATENT CLAIMS

1. Method for transmitting sensor signals (112, 122, 132) from at least two sensors (11 -13) of a vehicle brake (1), with the following steps:

- Providing a first sensor signal (112) of a first of the sensors (11-13) at a signal output (141) in a first transmission section (113); and

- Subsequent provision of a second sensor signal (122)

second of the sensors (11-13) at the signal output (141) in a second transmission section (123).

2. The method according to claim 1, wherein each transmission section (113, 123,

133) is preceded by an identification section (114, 124, 134) in which an identification signal is output at the signal output (141), which is suitable for the sensor (11-13), whose sensor signal (112, 122, 132) is subsequently output will identify.

3. The method of claim 2, wherein the identification signal at least

is temporarily outside a voltage range (21), which for the

Sensor signals (112, 122, 132) is fixed.

4. The method of claim 2 or 3, wherein the identification signal in

Identification section (114, 124, 134) has a predetermined voltage.

5. The method according to any one of claims 1 to 4, wherein a transmission sequence the successive provision of a predetermined number of

Transmission sections (113, 123, 133) and identification sections (114, 124, 134).

6. The method according to claim 5, in which a transmission sequence is started when at least one of the sensor signals (112, 122, 132) fulfills a predetermined criterion.

7. The method according to any one of claims 1 to 6, in which for at least one of

Transmission sections (113, 123, 133) a fixed period of time is specified.

8. The method according to claim 7, wherein for at least two different the

Transmission sections (113, 123, 133) different times are specified.

9. Vehicle brake (1) with a sensor arrangement (10) with at least two

Sensors (11 -13), characterized in that outputs (111, 121, 131) of the sensors (11 -13) are connected to inputs (142) of a multiplexer (14), via which they are successively connected to a signal output (141) of the Sensor arrangement (10) can be connected.

10. Vehicle brake (1) according to claim 9, wherein the sensor arrangement (10) has a microcontroller (15) which is coupled to control inputs (143) of the multiplexer (14) for actuating it.

11.Vehicle brake (1) according to claim 10, in which at least one input (152) of the microcontroller (15) is connected to at least one of the outputs (111, 121, 131) of the sensors (11-13).

12. The vehicle brake (1) according to claim 101, wherein the microcontroller (15) is set up to monitor the at least one of the outputs (111, 121, 131) in order to transmit a transmission sequence (22) of sensor signals (112, 122,

132) to start at least two sensors (11 -13).

13. Vehicle brake (1) according to one of claims 9 to 12, in which the

Sensor arrangement (10) is set up to carry out a method according to one of claims 1 to 8.