Method for transmitting information via wire

Abstract

The invention relates to a method for transmitting information over a line, in which first information is provided by a first sensor via a first signal, said first sensor being connected to the line via a current interface, and second information is provided by a second sensor via a second signal, said second sensor being connected to the line via a voltage interface, an information signal transmitted through the wire carries first information and second information, and the information signal is provided by modulating the first signal onto the second signal.

Description

Technical Field

[0001] The invention relates to a method for transmitting information via a line and to a sensor device for providing a signal which carries the information to be transmitted. Background Art

[0002] An electromechanical brake (EMB) is a braking system in which the braking pulse, the required energy transmission or the actuation of the brake mechanism, such as the brake pad, is realized electrically. To date, EMBs have been used wherever hydraulic, pneumatic or mechanical brake systems are used. This is so-called drive-by-wire technology, which is increasingly used in the field of steering and braking in vehicles.

[0003] In motor vehicles, controllers are often used to activate steering and braking functions. In this context, communication between the brake system and the controller is particularly important for electromechanical brakes.

[0004] In this case, externally commutated EMBs are also used. Brake actuators are used, which are connected to the associated controller via cables or electrical lines. The power electronics used are usually arranged in the controller. It should be noted that for EMBs, the rotor position of the motor, in particular the externally commutated motor, must be detected. For this purpose, a rotor position sensor (RPS) is used. In addition, the wheel speed must be read. For this purpose, it is known to use a wheel speed sensor (WSS: Wheel Speed ​​Sensor).

[0005] In many cases, so-called TMR sensors (TMR: tunnel magnetoresistance) are used as rotor position sensors. Such sensors are based on the magnetoresistance effect and are also called magnetic field sensors. Magnetic field sensors usually have a differential SIN / COS interface. The internal structure of a TMR sensor is equivalent to one or two Wheatstone bridges. For more information, see Figure 1 . Summary of the invention

[0006] Against this background, a method is proposed having the features of claim 1 and a sensor device according to claim 8. Embodiments are derived from the dependent claims and the description.

[0007] The proposed method is used to transmit information via a conductor, wherein first information is provided by a first sensor via a first signal, the first sensor being connected to the conductor via a current interface, and second information is provided by a second sensor via a second signal, the second sensor being connected to the conductor via a voltage interface. The first information and the second information are carried by an information signal transmitted via the conductor, wherein the information signal is provided by modulating the first signal onto the second signal. This modulation step can also be a step of the proposed method.

[0008] In one embodiment of the method, an analog sensor is used as the sensor. This means that the sensor used provides an analog signal as information carrier.

[0009] A wheel speed sensor can be used as the first sensor and a rotor position sensor can be used as the second sensor. They can be arranged or connected in series or in parallel with one another in the sensor arrangement.

[0010] In one embodiment, a cable harness is used as the conductor. The conductor can also be part of the cable harness.

[0011] After the information signal is transmitted, the first information and the second information can be extracted by demodulating the information signal.

[0012] Furthermore, a sensor device for providing an information signal is proposed, wherein the information signal is provided for transmission via a line. The sensor device comprises a first sensor having a current interface and being configured to provide a first signal, a second sensor having a voltage interface and being configured to provide a second signal, and a unit configured to modulate the first signal onto the second signal and thereby provide the information signal.

[0013] For example, the unit is obtained by simply connecting the two sensors to a line. If the second signal, for example the rotor position signal, is regarded as a carrier signal, the first signal, for example the wheel speed signal, is modulated onto the rotor position signal in an amplitude-modulated manner.

[0014] Further advantages and embodiments of the invention are apparent from the description and the accompanying drawings.

[0015] Of course, the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination but also in other combinations or alone, without departing from the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 An implementation of a TMR sensor is shown in a block diagram;

[0017] Figure 2 The graph shows Figure 1 The output signal of the TMR sensor in;

[0018] Figure 3 A speed sensor for measuring wheel speed is shown in an exploded view;

[0019] Figure 4 A speed sensor with a 2-wire current interface is shown in a block diagram;

[0020] Figure 5An embodiment of the described sensor device is shown in a block diagram;

[0021] Figure 6 An exemplary output signal variation curve is shown in a graph;

[0022] Figure 7 An exemplary signal variation curve is shown in a graph;

[0023] Figure 8 An embodiment of the proposed cable harness is shown;

[0024] Fig. 9 Another embodiment of the proposed sensor device is shown;

[0025] Fig.10 An exemplary signal variation curve is shown in a graph;

[0026] Fig.11 Another embodiment of the proposed cable harness is shown. DETAILED DESCRIPTION

[0027] The invention is schematically illustrated on the basis of embodiments in the drawings and is described in more detail below with reference to the drawings.

[0028] Figure 1 The block diagram shows the basic structure of a TMR sensor which is implemented as a full bridge and is designated overall by reference numeral 10. The figure shows a first bridge 12 and a second bridge 14, each of which has four resistors. In addition, a first connection 20 for SIN-, a second connection 22 for SIN+, a third connection 24 for a supply voltage Vcc, a fourth connection 26 for a supply voltage Vcc, a fifth connection 28 for COS+, a sixth connection 30 for COS-, a seventh connection 32 for ground GND and an eighth connection 34 for GND are shown.

[0029] The directions of the determined slices, namely SIN 40 and 42 and COS 44 and 46 , are indicated by arrows.

[0030] Figure 2 The variation of the TMR sensor output signal is shown in a graph 50. The reference angle [°] is plotted on the abscissa 52 of the graph 50 and the sensor output voltage [V] is plotted on the ordinate 54 thereof, which shows the variation of the differential sensor output signal, namely uSIN+60, uCOS+62, uSIN-64 and uCOS-66.

[0031] Ideally, the signal profile is sinusoidal or cosine-shaped with respect to the mechanical rotation of the rotor. The angle of the rotor position can be calculated from the sine and cosine using the arctangent2 function.

[0032] Wheel speed sensors are usually designed as Hall sensors. A distinction is made here between active and passive speed sensors. In the case of active sensors, a magnet is arranged in the sensor housing. These sensors sense the ferromagnetic sensor wheel. In the case of passive sensors, the sensor wheel itself is magnetic. This means that no magnet is arranged in the sensor itself.

[0033] Figure 3 A rotational speed sensor 100 for measuring the rotational speed of a wheel is shown in an exploded view. The rotational speed sensor 100 shown is associated with an encoder wheel 102. Components 104, 106, 108 serve for the mechanical connection of the sensor to the wheel.

[0034] Furthermore, the profile of the current pulse output signal 120 is shown.

[0035] In order to transmit the wheel speed information, a 2-wire current interface is usually used in the speed sensor. Compared with the voltage interface, the wire between the sensor and the controller can be omitted in this 2-wire current interface. Therefore, only two wires are required instead of three. Two voltage levels are used, namely a high and a low voltage, which, in combination with a resistor in the controller, generate a measurable voltage Uout. The resulting signal has a rectangular shape.

[0036] Figure 4 A rotation speed sensor with a 2-wire current interface is shown, which is designated overall by reference numeral 150. The figure shows a wheel rotation speed sensor 152 and a controller 154. An ASIC 160 is provided in the wheel rotation speed sensor 152, which has the connections VDD 162, Q164 and GND 166, a first capacitor 170, a second capacitor 172 and a resistor 174 as well as connections for (+) 175, (-) 176 and (Diag) 177.

[0037] The controller 154 is provided with a capacitor 180 and a resistor 182 (through which the voltage U out 184) for V DD A connector 190 and an additional connector 192 are provided.

[0038] Each wheel and EMB requires six wires for the transmission of the rotor position signal and two wires for the transmission of the wheel speed sensor information. For four wheels, this requires 32 wires. According to the proposed method, the number of wires per wheel can be reduced by two wires. Therefore, only 24 wires are required for all four wheels. In this way, costs can be reduced and the weight of the cable harness can also be reduced.

[0039] This is achieved using a special combination of a wheel speed sensor interface and a rotor position sensor interface. Here, the wheel speed information is modulated onto the rotor position signal. In this way, two wires can be saved per wheel compared to known methods.

[0040] The proposed sensor arrangement is a series connection consisting of a wheel speed sensor and a rotor position sensor. A total of six wires are required to lead to the controller. The individual wires are:

[0041] Supply voltage,

[0042] GND,

[0043] SIN+,

[0044] SIN-,

[0045] COS+,

[0046] COS-.

[0047] Figure 5 The basic structure of an embodiment of the described circuit arrangement is shown in a block diagram, which is denoted overall by reference numeral 200. The figure shows a wheel speed sensor 202 and a rotor position sensor 204, which are arranged in series with one another.

[0048] Here, wheel speed sensor 202 is schematically represented by a first ideal current source 210 , which is shown in series with a parallel connection consisting of a switch 212 and a second ideal current source 214 .

[0049] Rotor position sensor 204 has a first bridge 220 and a second bridge 222, each of which has four resistors. In addition, a first connection 230 for SIN-, a second connection 232 for SIN+, a third connection 234 for supply voltage Vcc, a fourth connection 236 for supply voltage Vcc, a fifth connection 238 for COS+, a sixth connection 240 for COS-, a seventh connection 242 for ground GND, and an eighth connection 244 for GND are shown. The direction of the determined layers is indicated by arrows, namely SIN 250 and 252 and COS 254 and 256.

[0050] The rectangular wheel speed signal is superimposed on a sine or cosine shaped (single ended) signal. Figure 6 The envelope of the curve in can be used to obtain wheel speed information. In addition, the rotor position is obtained by the arc tangent 2 (arcustangs2) function of the two differential voltages V(sin+)-V(sin-) and V(cos+)-V(cos-).

[0051] Figure 6 The profile of an exemplary output signal is shown in diagram 300. Graph 300, which plots time on its abscissa 302 and voltage on its ordinate 304, shows the profiles of SIN+ 310, SIN- 312, COS+ 314 and COS- 316.

[0052] Figure 7 An exemplary signal profile is shown in a graph 350. Graph 350 plots time [ms] on its abscissa 352 and voltage [V] on its ordinate 354, showing different voltage profiles. The figure shows the profiles of V(sin+) 360, V(sin-) 362, V(cos+) 364, V(cos-) 366, V(wss) 370, V(sin+)-V(sin-) 372 and V(cos+)-V(cos-) 374.

[0053] Figure 8 An embodiment of the proposed cable harness is shown, which is generally indicated by reference numeral 400. The figure shows a wheel speed sensor (WSS) 402 and a rotor position sensor (RPS) 404.

[0054] Obviously, in comparison with known embodiments, two wires leading from the wheels to the controller can be omitted.

[0055] In addition to Figure 5 In addition to the implementation method of Fig. 9 A further embodiment is shown in . The figure shows a sensor arrangement, which is designated as a whole by reference numeral 500. The figure shows a wheel speed sensor 502 and a rotor position sensor 504, which are arranged in parallel with each other.

[0056] Here, wheel speed sensor 502 is schematically represented by first ideal current source 510 , which is shown in series with a parallel connection consisting of switch 512 and second ideal current source 514 .

[0057] Rotor position sensor 504 has a first bridge 520 and a second bridge 522, each of which has four resistors. In addition, a first connection 530 for SIN-, a second connection 532 for SIN+, a third connection 534 for supply voltage Vcc, a fourth connection 536 for supply voltage Vcc, a fifth connection 538 for COS+, a sixth connection 540 for COS-, a seventh connection 542 for ground GND, and an eighth connection 544 for GND are shown. The direction of the determined layers is indicated by arrows, namely SIN 550 and 552 and COS 554 and 556.

[0058] Thus, the parallel connection of sensors replaces the Figure 6 The implementation scheme of WSS and RPS is connected in series.

[0059] The resulting signal change curve is as follows Fig.10 shown. Fig.10 A graph 600 is shown, on whose abscissa 602 time [ms] is plotted and on whose ordinate 604 voltage [V] is plotted. The figure shows the profiles of V(sin+) 610, V(sin-) 612, V(cos+) 614, V(cos-) 616, V(wss) 620, V(sin+)-V(sin-) 622 and V(cos+)-V(cos-) 624.

[0060] Compared to known solutions, two lines from the wheel to the control unit can also be omitted with the alternative embodiment shown.

[0061] Fig.11 An embodiment of a cable harness according to an alternative embodiment is shown and is generally indicated by reference numeral 650. The figure shows a WSS 652 and an RPS 654.

Claims

1. A method for transmitting information via a wire, wherein: The first information is provided by a first sensor via a first signal, the first sensor being connected to the conductor via a current interface, and The second information is provided by a second sensor via a second signal, wherein the second sensor is connected to the wire via a voltage interface, The information signal transmitted via the wire carries first information and second information, wherein the information signal is provided by modulating the first signal onto the second signal.

2. The method according to claim 1, wherein an analog sensor is used as the sensor.

3. The method according to claim 2, wherein: A wheel speed sensor (202, 402, 502, 652) is used as a first sensor, and a rotor position sensor (204, 404, 504, 654) is used as a second sensor.

4. The method according to claim 3, wherein the wheel speed sensor (202, 402, 502, 652) and the rotor position sensor (204, 404, 504, 654) are arranged in series with each other.

5. The method according to claim 3, wherein the wheel speed sensor (202, 402, 502, 652) and the rotor position sensor (204, 404, 504, 654) are arranged in parallel with each other.

6. The method according to any one of claims 1 to 5, wherein a cable harness (400, 650) is used as the conductor.

7. The method according to any one of claims 1 to 6, wherein after transmitting the information signal, the first information and the second information are extracted by demodulating the information signal.

8. A sensor device for providing an information signal, the information signal being arranged to be transmitted via a conductor, the sensor device comprising: a first sensor having a current connection and being designed to provide a first signal, a second sensor having a voltage connection and being designed to provide a second signal, and A unit is configured to modulate the first signal onto the second signal and thereby provide an information signal.

9. The sensor device according to claim 8, wherein: The first sensor is a wheel speed sensor (202, 402, 502, 652), and the second sensor is a rotor position sensor (204, 404, 504, 654).

10. The sensor device according to claim 9, wherein the wheel speed sensor (202, 402, 502, 652) and the rotor position sensor (204, 404, 504, 654) are arranged in series with one another.

11. The sensor device according to claim 9, wherein the wheel speed sensor (202, 402, 502, 652) and the rotor position sensor (204, 404, 504, 654) are arranged in parallel with each other.

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