Sensor arrangement with a sensor for redundant acquisition of a measured quantity and an electro-hydraulic braking system with such a sensor arrangement

Abstract

Sensor arrangement with a sensor (RS) for detecting a measured quantity, comprising - a first evaluation unit (ECU1) with a first measuring resistor (R1) to generate a measuring voltage drop (U) M ) a sensor signal representing the measured quantity is supplied to the sensor (RS), - a second evaluation unit (ECU2) with a second measuring resistor (R2), which is used to generate a measuring voltage drop (U) M ) a sensor signal representing the measured quantity is supplied to the sensor (RS), - a first voltage source (BN1) which is connected to the first evaluation unit (ECU1), - a second voltage source (BN2) which is connected to the second evaluation unit (ECU2), and - Switching devices (DZ11, DZ12, DZ21) which are connected to the sensor (RS) and are designed in such a way that in the event of a failure of an evaluation unit (ECU1, ECU2) a measurement voltage drop (U M) can be generated at the measuring resistor (R1, R2) of the other evaluation unit (ECU1, ECU2).

Description

[0001] The invention relates to a sensor arrangement with a sensor for redundantly acquiring a measured quantity. Furthermore, the invention relates to an electro-hydraulic braking system with a sensor arrangement according to the invention.

[0002] Automated driving systems utilize electro-hydraulic braking systems, which are fundamentally designed as remotely controlled systems. This means that a braking request can be made via electrical control signals and implemented by the system without driver intervention. For safety reasons, a sufficiently high availability of the braking system or the remotely controlled braking function must be ensured.

[0003] Since in automated driving the responsibility for safe driving is transferred from the driver to the vehicle and the driver no longer needs to constantly monitor the driving situation, redundancy in the braking system, i.e. a redundancy in the brake pressure build-up, is required.

[0004] Such a braking system with redundant brake pressure build-up is known from DE 10 2014 220 441 A1 of the applicant. Such a braking system comprises a master brake cylinder designed as a tandem master brake cylinder, an electrically controlled brake booster upstream of the master brake cylinder, four hydraulically actuated wheel brakes, and a first electro-hydraulic brake control device (first brake control unit HECU) which is built with a first electronic control unit (ECU) and a first hydraulic control unit (HCU), as well as a second electro-hydraulic brake control device (second brake control unit HECU) which is built with a second electronic control unit (ECU) and a second hydraulic control unit (HCU).The first hydraulic control unit is equipped with a pressure control valve assembly for setting individual brake pressures for each wheel, an electrically controlled pressure source, and an individual pressure outlet for each wheel brake. Furthermore, a second electro-hydraulic brake control unit (second brake control unit HECU) is provided as a backup system. This second hydraulic control unit comprises a second pressure control valve assembly for setting individual brake pressures for each wheel brake and an individual pressure outlet for each wheel brake. This second brake control unit is connected in series between the first brake control unit and the wheel brakes. The brake booster is controlled by the second brake control unit, i.e., the second electronic control unit.

[0005] This backup system requires the same wheel speed information as the first electro-hydraulic brake control device. In this known brake system according to DE 10 2014 220 441 A1, two wheel speed sensors are assigned to each wheel brake, so that the signal from one wheel speed sensor is fed to the first electronic control unit (ECU) via a separate signal line, and the signal from the other wheel speed sensor is fed to the second electronic control unit (ECU) via a separate signal line. Furthermore, DE 10 2014 220 441 A1 points out that instead of two devices per wheel brake for detecting wheel speed, a redundant device for detecting wheel speed (redundant wheel speed sensor) can also be used, which provides two independent wheel speed signals.

[0006] Based on this prior art, the object of the invention is to provide a simply constructed sensor arrangement with a single sensor, in particular a speed sensor, which provides the measured variable, in particular the speed, for two evaluation units, in particular two electronic control units, e.g. of an electro-hydraulic brake system with backup system.

[0007] This problem is solved by a sensor arrangement having the features of claim 1 and the features of claim 7.

[0008] According to the first-mentioned solution, the sensor arrangement with a sensor for detecting a measured quantity comprises: - a first evaluation unit with a first measuring resistor, to which a sensor signal representing the measured quantity is supplied to generate a measuring voltage drop, - a second evaluation unit with a second measuring resistor, to which a sensor signal representing the measured quantity is supplied to generate a measuring voltage drop, - a first voltage source which is connected to the first evaluation unit, - a second voltage source, which is connected to the second evaluation unit, and - Switching devices which are connected to the sensor and are designed in such a way that, in the event of a failure of one evaluation unit, a measurement voltage drop can be generated across the measuring resistor of the other evaluation unit.

[0009] With this sensor arrangement, in the event of a failure of one of the two evaluation units, which may be designed, for example, as electronic control units of an electro-hydraulic brake system, the remaining evaluation unit is provided with the complete sensor information of the sensor, preferably designed as a speed sensor for detecting the speed of wheels of a vehicle.

[0010] A particularly advantageous embodiment of the invention relates to a sensor arrangement in which - the sensor is connected to the first voltage source via the first measuring resistor on the voltage side and to a ground via the second measuring resistor on the ground side, - a first diode-Zener diode combination is connected in parallel to the first measuring resistor, - a second diode-Zener diode combination is connected in parallel to the second measuring resistor, and - the first and second diode-Zener diode combinations are each designed with a breakdown voltage that is greater than the measurement voltage drop, such that a breakdown of the associated diode-Zener diode combination can be effected if an evaluation unit fails.

[0011] With such a diode-Zener diode combination, it is achieved that if one of the two evaluation units fails, the corresponding diode-Zener diode combination breaks down, so that the sensor can continue to be supplied with an operating voltage via one of the two voltage sources.

[0012] It is particularly advantageous if, as further developed, a second diode-Zener diode combination is provided, which is arranged between the sensor and the second voltage source. This ensures that even if one of the two voltage sources fails, the sensor continues to be powered by the intact voltage source.

[0013] A further advantageous embodiment of the invention provides that - one end of the second diode-Zener diode combination is connected to a ground terminal of the second evaluation unit, and - a further second diode-Zener diode combination is provided, which is connected to a ground connection of the first evaluation unit.

[0014] This ensures that, even in this embodiment of the sensor arrangement according to the invention, the continued supply of voltage to the sensor by the intact voltage source is guaranteed in the event of a failure of one of the two voltage sources.

[0015] A particularly advantageous embodiment of the sensor arrangement is characterized by the fact that - a first switch is provided, with which the sensor can be connected to the first voltage source via the first measuring resistor, - a second switch is provided, with which the sensor can be connected to the second voltage source via the second measuring resistor, and - the sensor is connected to a ground on the ground side.

[0016] In this sensor arrangement according to the invention, the sensor signal from the sensor, preferably designed as a speed sensor for detecting the rotational speed of the wheels of a vehicle, is acquired by the evaluation units by means of two independently operable switches. If one of the two evaluation units fails, the remaining evaluation unit can acquire the complete sensor information via the closed switch.

[0017] According to the second solution, the sensor arrangement with a sensor for detecting a measured quantity comprises: - a first evaluation unit with a first measuring amplifier, - a second evaluation unit with a second measuring amplifier, - a first voltage source which is connected to the first evaluation unit, - a second voltage source, which is connected to the second evaluation unit, - a low-side measuring resistor to which a sensor signal representing the measured quantity is supplied to generate a measuring voltage drop, the sensor being connected to ground on the sensor side, wherein the sensor is connected to ground on both the first and second measuring amplifiers to supply the measuring voltage drop to the first and second measuring amplifiers, and - a first diode, with which the sensor is connected on the voltage side to the first or the second voltage source.

[0018] In this solution according to the invention, only a single measuring resistor, a so-called low-side measuring resistor, is used compared to the first-mentioned solution according to the invention. The measuring voltage drop across this low-side measuring resistor is simultaneously supplied to both evaluation units, so that if one of the two evaluation units fails, this measuring voltage drop can still be evaluated by the remaining evaluation unit with the complete sensor information from the sensor, which is preferably designed as a speed sensor for detecting the rotational speed of the wheels of a vehicle.

[0019] According to an advantageous embodiment of the invention according to the second-mentioned solution, a second diode is provided, wherein the sensor is connected on the voltage side to the first voltage source via the first diode and to the second voltage source via the second diode.

[0020] Furthermore, according to a preferred embodiment of the invention, a data line is provided to compare the measured quantity measured by the sensor, connecting the first and the second evaluation unit.

[0021] For the use of the sensor arrangement according to the invention in an electro-hydraulic braking system, the first and second evaluation units are designed as the first and second electronic control and regulation units of such an electro-hydraulic braking system.

[0022] Such an electro-hydraulic braking system includes: - a first electro-hydraulic brake control device, which is built with a first electronic control and regulating unit and a first hydraulic control and regulating unit, - a second electro-hydraulic brake control device, which is built with a second electronic control and regulating unit and a second hydraulic control and regulating unit, and a sensor arrangement according to the invention.

[0023] The invention is described in detail below with reference to exemplary embodiments and the accompanying figures. These show: Fig. 1 a block diagram of a section of an electro-hydraulic brake system with a first embodiment of a sensor arrangement according to the invention, Fig. 2 a block diagram of a section of an electro-hydraulic brake system with a second embodiment of a sensor arrangement according to the invention, and Fig. 3 a block diagram of a section of an electro-hydraulic brake system with a third embodiment of a sensor arrangement according to the invention.

[0024] The Fig. 1, Fig. 2 and Fig. Figure 3 shows a section of an electro-hydraulic braking system of a vehicle, as known, for example, from the applicant's DE 10 2014 220 441 A1, which was explained at the beginning. These figures show only the first and second brake control units HECU1 and HECU2, as well as a sensor arrangement with a speed sensor as sensor RS, of the electro-hydraulic braking system described therein.

[0025] The first brake control unit HECU1 comprises a first hydraulic control unit HCU1 and a first electronic control unit ECU1. Similarly, the second brake control unit HECU2 consists of a second hydraulic control unit HCU2 and a second electronic control unit ECU2.

[0026] Furthermore, two electrical systems, BN1 and BN2, are provided as power sources. The first electronic control unit (ECU1) is supplied with an operating voltage via connection A11 from the first electrical system, BN1, and is connected to the vehicle's ground (GND) via connection A13. Similarly, the second electronic control unit (ECU2) is supplied with an operating voltage via connection A21 from the second electrical system, BN2, and a connection A23 of this second electronic control unit (ECU2) is connected to the vehicle's ground (GND).

[0027] The first and second electronic control units, ECU1 and ECU2, each represent an evaluation unit in accordance with the sensor arrangement according to the invention. The exemplary embodiments of this sensor arrangement according to the invention are described in detail below with reference to the Fig. 1, Fig. 2 and Fig. 3 described and explained.

[0028] According to Fig. 1 The sensor arrangement comprises the following components: - the first evaluation unit designed as the first electronic control and regulation unit ECU1 with connections A11 and A13 as well as a further connection A12, - the second evaluation unit designed as a second electronic control and regulating unit ECU2 with connections A21 and A23 as well as a further connection A22, - a sensor RS designed as a speed sensor with two terminals A3 and A4, wherein terminal A3 is connected to terminal A12 of the first electronic control unit ECU1 and the other terminal A4 is connected to terminal A22 of the second electronic control unit ECU2, - the first measuring resistor R1 assigned to one of the first electronic control and regulating units ECU1, which connects terminal A11 to terminal A12 of the first electronic control and regulating unit ECU1, - a second measuring resistor R2 assigned to the second electronic control unit ECU2, which connects terminal A21 to terminal A22 of the second electronic control unit ECU2, - a first measuring amplifier M1 arranged in the first electronic control unit ECU1, to which a measuring voltage drop U M of the first measuring resistor R1, - a second measuring amplifier M2 arranged in the second electronic control unit ECU2, to which a measuring voltage drop U M the second measuring resistor R2 is supplied, - a first diode-zener diode combination DZ11 consisting of a series connection of a diode and a zener diode, which is connected in parallel to the first measuring resistor R1 to the terminals A11 and A12 of the first electronic control unit ECU1, so that the diode is connected in forward bias to the first on-board network BN1 and the zener diode in reverse bias to the terminal A3 of the sensor RS or the terminal A12 of the first electronic control unit ECU1, - another first diode-zener diode combination DZ12 with a diode and a zener diode, wherein the diode is connected in forward bias to the second on-board network BN2 and the zener diode is connected in reverse bias to terminal A3 of sensor RS or to terminal A12 of the first electronic control unit ECU1, and - a second diode-zener diode combination DZ21 consisting of a diode and a zener diode, which is connected in parallel to the second measuring resistor R1 to the terminals A22 and A23 of the second electronic control unit ECU2, so that the diode is connected in forward direction to ground GND and the zener diode is connected in reverse direction to terminal A4 of sensor RS or terminal A22 of the second electronic control unit ECU2.

[0029] In addition to the second diode-Zener diode combination DZ21, a further second diode-Zener diode combination DZ22 consisting of a diode and a Zener diode can be used, so that the diode is connected in forward bias to the ground GND of the first electronic control unit ECU1 and the Zener diode is connected in reverse bias to the terminal A4 of the sensor RS or the terminal A22 of the second electronic control unit ECU2.

[0030] In this sensor arrangement, the first electronic control unit ECU1 receives the wheel speed information via the high-side of the sensor RS, and the second electronic control unit ECU2 receives it via the low-side of the sensor RS.

[0031] During operation of the two electronic control units ECU1 and ECU2 with active sensor RS, a sensor signal representing the measured quantity, i.e., the rotational speed, from sensor RS, which is configured as a speed sensor, is supplied to the two measuring resistors R1 and R2. The resulting measurement voltage drop U across the two measuring resistors R1 and R2 M The signal is fed to the measuring amplifier M1 or M2, respectively.

[0032] The diode-Zener diode combinations DZ11, DZ12 and DZ21 are designed such that the respective breakdown voltage U DD slightly larger, e.g., 300 mV larger than the voltage value of the measured voltage drop U Mat the respective measuring resistor R1 or R2.

[0033] When the two brake control units HECU1 and HECU2 are operating without problems, the diode-Zener diode combinations DZ11, DZ12 and DZ21 are in their blocked state.

[0034] If a fault occurs, such that, for example, the first electronic control unit ECU1 fails, the breakdown voltage U of the two diode-Zener diode combinations DZ11 and DZ12 drops. DD This causes these two diode-Zener diode combinations DZ11 and DZ12 to operate in forward bias. This ensures that the sensor RS continues to be supplied with the operating voltage, so that the measuring voltage U continues to be present across the second measuring resistor R2. M The resulting signal is fed to the second measuring amplifier M2 of the second electronic control unit ECU2. In this case, the second diode-Zener diode combination DZ21 remains in its blocking mode.

[0035] Should one of the two on-board networks BN1 or BN2 fail, the sensor RS will still be supplied with operating voltage via the diode-Zener diode combination DZ11 or DZ12 connected to the on-board network BN1 or BN2 that has not failed.

[0036] If, on the other hand, the second electronic control unit ECU2 fails, a voltage drop is generated across the second diode-Zener diode combination DZ21, which is at least equal to its breakdown voltage U. DD This corresponds to the breakdown of this diode-Zener diode combination DZ21. Thus, in this case too, the voltage supply of the sensor RS is ensured via this diode-Zener diode combination DZ21, so that a measurement voltage drop U occurs across the first measuring resistor R1 of the first electronic control unit ECU1. M is generated.

[0037] Additionally, a second diode-Zener diode combination DZ22 can also be used, so that, for example, in the event of a defect at a ground connection of the ground GND, the diode-Zener diode combination DZ21 or DZ22 connected to the intact ground connection ensures the voltage supply of the sensor RS.

[0038] The sensor arrangement according to Fig. 2 includes the following components: - the first evaluation unit designed as the first electronic control and regulation unit ECU1 with connections A11 and A13 as well as a further connection A12, - the second evaluation unit designed as a second electronic control and regulating unit ECU2 with connections A21 and A23 as well as a further connection A22, - a sensor RS designed as a speed sensor with two terminals A3 and A4, wherein terminal A3 is connected to terminal A12 of the first electronic control unit ECU1 and simultaneously to terminal A22 of the second electronic control unit ECU2, while the other terminal A4 of the sensor RS is connected to ground GND, - the first measuring resistor R1 assigned to the first electronic control unit ECU1, which is connected on the one hand to the terminal A11 via a first switch S1 and on the other hand to the terminal A12 of the first electronic control unit ECU1 via a forward-biased diode D1, - a second measuring resistor R2 assigned to the second electronic control unit ECU2, which is connected on one side to terminal A21 via a second switch S2 and on the other side to terminal A22 of the second electronic control unit ECU2 via a forward-biased diode D2, - a first measuring amplifier M1 arranged in the first electronic control unit ECU1, to which a measuring voltage drop U M the first measuring resistor R1 is supplied, and - a second measuring amplifier M2 arranged in the second electronic control unit ECU2, to which a measuring voltage drop U M is supplied to the second measuring resistor R2.

[0039] In this sensor arrangement according to Fig. 2. The speed detection of both electronic control units ECU1 and ECU2 can be carried out independently of each other by closing the respective switch S1 or S2.

[0040] In normal operation of the electro-hydraulic braking system according to Fig. 2. In normal operation, speed measurement is performed by only one of the two electronic control units, ECU1 or ECU2. For example, in normal operation, speed measurement is performed only by the first electronic control unit, ECU1, by closing switch S1 on this first electronic control unit, ECU1. When switch S1 is closed, a measurement voltage drop U is observed. MA signal is generated at the first measuring resistor R1, which is fed to the measuring amplifier M1 of the first electronic control unit ECU1. The second switch S2 of the second electronic control unit ECU2 remains open. The sensor information, i.e., the wheel speed information, can be supplied to this second electronic control unit ECU2 via a data line L connecting the two electronic control units ECU1 and ECU2.

[0041] However, if this first electronic control unit ECU1 fails, the switch S2 is closed by the second control unit ECU2, so that there is now a measuring voltage drop U across the second measuring resistor R2. M is generated, which is fed to the measuring amplifier M2 of the second electronic control unit ECU2.

[0042] However, if, after trouble-free operation of the electro-hydraulic braking system according to Fig. 2. The same applies to the second electronic control unit ECU2.

[0043] The sensor arrangement according to Fig. 3 includes the following components: - the first evaluation unit designed as the first electronic control and regulation unit ECU1 with connections A11 and A13 as well as a further connection A12, - the second evaluation unit designed as a second electronic control and regulating unit ECU2 with connections A21 and A23 as well as a further connection A22, - a sensor RS designed as a speed sensor with two terminals A3 and A4, wherein terminal A3 is connected to the vehicle electrical system BN1 via a forward-biased diode D11 and simultaneously to the vehicle electrical system BN2 via another diode D12, while the other terminal A4 of the sensor RS is connected to both terminal A12 of the first electronic control unit ECU1 and to terminal A22 of the second electronic control unit ECU2, and this terminal A4 is simultaneously connected to ground GND via a low-side measuring resistor R, - a first measuring amplifier M1 arranged in the first electronic control unit ECU1, with a first input connected to terminal A12 and a second input connected to ground GND via terminal A13, and - a second measuring amplifier M2 arranged in the second electronic control unit ECU2, with a first input connected to terminal A22 and a second input connected to ground GND via terminal A23.

[0044] In this sensor arrangement according to Fig. 3. Only a single measuring resistor, namely a low-side measuring resistor R, is used, whose measuring voltage drop U MThe signal is simultaneously supplied via connection A12 to the first electronic control unit (ECU1) and via connection A22 to the second electronic control unit (ECU2). This allows both ECU1 and ECU2 to independently acquire sensor information, particularly wheel speed information. This wiring configuration ensures that if one of the two ECUs fails, the functioning ECU can compensate for the measurement voltage drop U. M can be detected via connection A12 or A22.

[0045] The sensor RS is powered via the two vehicle electrical systems BN1 and BN2, so that if one of the two vehicle electrical systems BN1 or BN2 fails, the power supply to the sensor RS is still ensured via the intact vehicle electrical system BN1 or BN2.

Claims

[1] Sensor arrangement with a sensor (RS) for detecting a measured quantity, comprising - a first evaluation unit (ECU1) with a first measuring resistor (R1) to generate a measuring voltage drop (U) M ) a sensor signal representing the measured quantity is supplied to the sensor (RS), - a second evaluation unit (ECU2) with a second measuring resistor (R2), which is used to generate a measuring voltage drop (U) M ) a sensor signal representing the measured quantity is supplied to the sensor (RS), - a first voltage source (BN1) which is connected to the first evaluation unit (ECU1), - a second voltage source (BN2) which is connected to the second evaluation unit (ECU2), and - Switching devices (DZ11, DZ12, DZ21) which are connected to the sensor (RS) and are designed in such a way that in the event of a failure of an evaluation unit (ECU1, ECU2) a measurement voltage drop (U M) can be generated at the measuring resistor (R1, R2) of the other evaluation unit (ECU1, ECU2). [2] Sensor arrangement according to claim 1, wherein - the sensor (RS) is connected to the first voltage source (BN1) via the first measuring resistor (R1) and to a ground (GND) via the second measuring resistor (R2) on the ground side, - a first diode-Zener diode combination (DZ11) is connected in parallel to the first measuring resistor (R1), - a second diode-Zener diode combination (DZ21) is connected in parallel to the second measuring resistor (R2), and - the first and second diode-Zener diode combination (DZ11, DZ21) each with a breakdown voltage (U DD ) is formed, which is greater than the measuring voltage drop (U) M ) is such that if an evaluation unit (ECU1, ECU2) fails, a breakdown of the associated diode-Zener diode combination (DZ11, DZ21) can occur. [3] Sensor arrangement according to claim 1 or 2, wherein a further first diode-Zener diode combination (DZ12) is provided, which is arranged between the sensor (RS) and the second voltage source (BN2). [4] Sensor arrangement according to one of the preceding claims 2 or 3, wherein - one end of the second diode-Zener diode combination (DZ21) is connected to a ground connection (A23) of the second evaluation unit (ECU2), and - a further second diode-Zener diode combination (DZ22) is provided, which is connected to a ground connection (A13) of the first evaluation unit (ECU1). [5] Sensor arrangement according to claim 1, wherein - a first switch (S1) is provided, with which the sensor (RS) can be connected to the first voltage source (BN1) via the first measuring resistor (R1), - a second switch (S2) is provided, with which the sensor (RS) can be connected to the second voltage source (BN2) via the second measuring resistor (R2), and - the sensor (RS) is connected to a ground (GND) on the ground side. [6] Sensor arrangement according to one of the preceding claims, wherein - the first evaluation unit (ECU1) includes a first measuring amplifier (M1), to which the measuring voltage drop (U) M1 ) of the first measuring resistor (R1), and - the second evaluation unit (ECU2) includes a second measuring amplifier (M1), to which the measuring voltage drop (U) m ) of the second measuring resistor (R2). [7] Sensor arrangement with a sensor (RS) for detecting a measured quantity, comprising - a first evaluation unit (ECU1) with a first measuring amplifier (M1), - a second evaluation unit (ECU2) with a second measuring amplifier (M2, - a first voltage source (BN1) which is connected to the first evaluation unit (ECU1), - a second voltage source (BN2) which is connected to the second evaluation unit (ECU2), - a low-side measuring resistor (R) to generate a measuring voltage drop (U) m ) a sensor signal representing the measured quantity is supplied to the sensor (RS), which is connected to the sensor (RS) on the ground side, whereby the measurement voltage drop (U) is supplied m ) the sensor (RS) is connected to the ground side of the first and second measuring amplifiers (M1, M2) and - a first diode (D11) with which the sensor (RS) is connected on the voltage side to the first or the second voltage source (BN1, BN2). [8] Sensor arrangement according to claim 7, in which a second diode (D12) is provided, wherein the sensor (RS) is connected on the voltage side via the first diode (D11) to the first voltage source (BN1) and via the second diode (D12) to the second voltage source (BN2). [9] Sensor arrangement according to one of the preceding claims, in which a data line (L) is provided for comparing the measured quantity, which connects the first and the second evaluation unit (ECU1, ECU2). [10] Sensor arrangement according to one of the preceding claims, wherein the sensor (RS) is a speed sensor. [11] Sensor arrangement according to one of the preceding claims, wherein the first and second evaluation unit (ECU1, ECU2) are designed as the first and second electronic control and regulating unit of an electro-hydraulic brake system. [12] Electro-hydraulic braking system comprising: - a first electro-hydraulic brake control device (HECU1) comprising a first electronic control unit (ECU1) and a first hydraulic control unit (HCU1), - a second electro-hydraulic brake control device (HECU2) which is built with a second electronic control unit (ECU2) and a second hydraulic control unit (HCU2), and - a sensor arrangement according to one of the preceding claims.

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