DE102010003254A1 - Method for checking short circuit in control unit of motor car, involves checking whether two signals resting at terminal are equal to or under threshold values in relation to voltages, respectively such that defect of sensor is detected - Google Patents

Abstract

The method involves applying two voltages to a terminal (12), and checking whether two measurement signals resting at another terminal (14) are equal to or under predetermined threshold values in relation to the voltages, respectively such that defect of a sensor (10) e.g. acceleration sensor and angular rate sensor, is detected. Short circuit checking process is carried out in a control unit (30) of a motor car. The measurement signals of the sensor are not utilized by the control unit during starting or shutdown of a combustion engine of the motor car. An independent claim is also included for a control unit for a motor car, comprising a memory component.

Description

The present invention relates to a short-circuit verification method of a sensor having at least one first and one second connection, which are arranged adjacent to one another, while a first measurement signal of the sensor can be output via the first connection and a second measurement signal of the sensor can be output via the second connection. Furthermore, the present invention relates to a control unit of a motor vehicle with a short-circuit verification method.

Sensors in a motor vehicle provide measurement signals that are used, for example, in a safety-relevant sensor circuit of the motor vehicle. This safety-related sensor circuit is in particular a system for electronic stability control of the motor vehicle.

A sensor that provides measurement signals for such a stability control system is, for example, a biaxial acceleration sensor. The biaxial acceleration sensor is a sensor component and performs an acceleration measurement along the X axis of the motor vehicle (longitudinal axis of the motor vehicle) and along the Y axis of the motor vehicle (transverse axis of the motor vehicle). The measurement signals of the acceleration sensor are output at two adjacent terminals of the sensor component and transmitted to a control unit of the motor vehicle. Within the control unit, a plausibility check of the respective supplied measurement signals takes place.

During operation of the motor vehicle, there may be a short circuit between the terminals of the sensor, which output the measurement signals. This short circuit is caused, for example, by conductive particles that accumulate between adjacent output terminals. With the help of the plausibility check in the control unit, however, it is not possible to detect that such a short circuit exists. This is especially the case when both terminals output measurement signals in a similar range of values, so that their plausibility range is similar or the same. As a result, one of the connections will supply incorrect measurement signals, but this will not be detected by the control unit. As a result, there are miscalculations in the stability control system of the motor vehicle.

The object of the present invention is therefore to provide a method with which a malfunction of the sensor compared to the prior art is safer recognizable.

The above object is achieved by a short-circuit checking method of a sensor according to claim 1 and a control unit of a motor vehicle having a short-circuit checking method according to claim 7. Further advantageous embodiments will become apparent from the following description, drawings and the dependent claims.

A short-circuit checking method of at least one sensor having at least one first and one second terminal adjacent to one another while a first measuring signal of the sensor and a second measuring signal of the sensor can be output via the first terminal comprises the following steps: applying a thereafter, or simultaneously, checking whether a first signal applied to the second terminal is equal to or below a predeterminable first limit value with respect to the first voltage, if so applying a second voltage to the first terminal and after or simultaneously checking that a second signal applied to the second terminal is equal to or above a predeterminable second limit with respect to the second voltage, if so, determining that the sensor is defective.

The short-circuit verification method according to the invention is carried out in a sensor of a motor vehicle, in particular in a control unit of the motor vehicle. The first and the second measurement signal of the sensor are used in a stability control system of the motor vehicle, wherein the first and the second outputable measurement signal of the sensor are an analog measurement signal.

By means of the short-circuit verification method according to the invention, the first terminal of the sensor, which is also referred to as the first output terminal, is used as the input. Here, a signal in the form of the first voltage is impressed from the outside. The first voltage is in particular 0 volts.

The second output terminal of the sensor is now checked for whether the voltage impressed on the first output terminal affects the second output terminal. Therefore, after applying the first voltage to the first output terminal, the first signal of the second output terminal is detected. The recording can be done online or after a predefined waiting time. The waiting time depends on the type of sensor and is for example 1.4 ms. The detected first signal is compared with the predeterminable first limit value to determine an influence of the second terminal by the first voltage applied to the first terminal.

By way of example, this will be explained on the basis of the impressed 0 volt signal. The sensor gives at this time via the second port any measurement signal or no measurement signal. Alternatively, the sensor can be brought into a state in which it outputs definable measuring signals. For example, the first and second ports first output a sense signal of either 0V or 2.5V. Subsequently, the 0 volt signal is applied to the first output terminal. At the same time or after a predeterminable time, the first signal output by the second output terminal is detected. If the first signal of the second output terminal drops and is equal to or lies below the first predefinable limit value, this is a first indication of a short circuit between the first and the second output terminal. In an extreme case, the measuring signal of the second terminal drops down to the voltage of 0 volts applied to the first terminal. Thus, for example, also the first limit value can be set substantially equal to the first impressed voltage.

In conventional operation of the sensor, the sensor typically outputs a voltage in the range of 0.5 volts to 4.5 volts as the first and second measurement signals. If a short circuit now occurs between the first output terminal and the second output terminal, the voltages of the first and the second measurement signal are equal to each other without leaving the range of 0.5 volts to 4.5 volts.

If the measurement signal of the second output terminal does not follow the first voltage applied to the first output terminal, then the sensor is in order and there is no short circuit between the adjacent output terminals.

However, if the measurement signal of the second terminal follows the first voltage impressed on the first output terminal, a second signal in the form of the second voltage is impressed on the first output terminal. The second voltage is in particular the maximum permissible supply voltage of the sensor. This is, for example, substantially 5 volts. Analogously to the steps described above, it is also checked here whether the second signal of the second output terminal follows the second voltage impressed on the first output terminal. If this is the case, then there is a short circuit between the first and the second adjacent output terminal. Otherwise, it is determined that the sensor is OK.

An advantage of the present short circuit verification method is that an easy-to-implement method is provided to provide a short circuit between adjacent output terminals of a sensor. Furthermore, in particular with regard to the use in a motor vehicle, no further components are required to carry out this method. In addition, the functionality of a sensor can be safely checked there, where a plausibility check of the measurement signals supplied by the sensor does not lead to a detection of an error.

Furthermore, in an advantageous embodiment, the sensor is an at least two-axis acceleration sensor or a rotation rate sensor. In this case, an acceleration along an X-axis of the motor vehicle is output via the first output connection as the first measurement signal of the sensor, that is, the acceleration along the longitudinal axis of the motor vehicle. Accordingly, an acceleration along the Y axis of the motor vehicle is output via the second output connection as the second measuring signal, that is to say along the transverse axis of the motor vehicle.

Moreover, it is advantageous if the short-circuit checking method is stored in a control unit of a motor vehicle, while the first terminal of the sensor is connected via a first line to a first input of the control unit and the second terminal of the sensor via a second line to a second input of the control unit is connected, wherein the application of the first and the second voltage by means of the control unit takes place. In this way, the short circuit verification method according to the invention can be carried out in a control unit of a motor vehicle. Advantageously, the short circuit checking method is performed in the control unit during a period in which the first and the second measuring signal of the sensor are not required by the control unit, in particular during starting or stopping of an internal combustion engine of the motor vehicle. In this way it is possible that the stability control system of the motor vehicle misses no measurement signals when they are needed. Usually, the stability control system does not require any measuring signals during the starting or stopping of the internal combustion engine, since the motor vehicle is still or already at this point in time. To further improve the method, the sensor can be brought into a defined state during this period in which it outputs definable measuring signals of, for example, 0 volts or 2.5 volts.

A control unit of a motor vehicle has a memory component in which a short circuit verification method according to the invention is stored. The advantages of the short circuit verification method have been explained above. By means of the control unit, the short-circuit verification method according to the invention can thus be realized with all its advantages in a motor vehicle. One Advantage of the control unit is in this case that a malfunction of the stability control system of the motor vehicle due to erroneous measurement signals of a sensor is avoidable. Thus, the safety in the operation of the motor vehicle for a user is further increased.

In the following, the present invention will be described in detail by way of an embodiment and with reference to the accompanying drawings. Show it:

1 a schematic representation of a control unit and a sensor connected thereto and

2 a schematic process flow of a short-circuit verification method according to the invention of a sensor.

The short circuit verification method is performed in a control unit of a motor vehicle and is stored there. However, the present short circuit verification method is not limited to use in a motor vehicle, but can be used wherever a sensor outputs measurement signals to two adjacent terminals. The measurement signals output by the sensor are used in particular for use in a safety system, such as a stability control system of a motor vehicle.

Referring to 1 is a sensor 10 with a first connection 12 and a second port 14 provided. About the first connection 12 a first measurement signal is output and via the second connection 14 a second measuring signal is output. The two measurement signals are preferably in the form of a voltage. Furthermore, the two measuring signals can have the same sign (plus or minus) or different signs. Alternatively, a measuring signal is applied to only one of the two output connections. The two connections 12 . 14 are therefore also referred to as the output port. The first 12 and second output port 14 are adjacent to each other in the sensor 10 arranged. For example, the first one 12 and the second connection 14 designed in the form of two pins or connecting pins.

At the sensor 10 it is in particular a biaxial acceleration sensor. In this case will be over the first port 12 as the first measurement signal an acceleration of the motor vehicle along the X-axis output, ie along the longitudinal axis of the motor vehicle. Accordingly, via the second port 14 as the second measuring signal an acceleration of the motor vehicle along the Y-axis output, ie along the transverse axis of the motor vehicle.

The first connection 12 is by means of a first line 20 with a first entrance 32 a control unit 30 a motor vehicle connected. The second connection 14 is over a second line 22 with a second entrance 34 the control unit 30 connected. In particular, the first one 32 and second entrance 34 the control unit 30 an A / D converter 40 in the control unit 30 assigned. The two entrances 32 . 34 are preferably analog inputs or combi ports.

Furthermore, the measuring signals of the sensor 10 analog measurement signals.

In the operation of the motor vehicle is by the sensor 10 the first measurement signal from the first port 12 over the first line 20 to the first entrance 32 transmitted. About the second connection 14 becomes the second measuring signal via the second line 22 to the second entrance 34 transmitted. The control unit 30 evaluates the transmitted first and second measurement signals and subjects them to a plausibility check.

During operation of the motor vehicle, however, it may happen that conductive particles between the first port 12 and the second port 14 attach and cause a short circuit between the two terminals 12 . 14 to lead. Especially if over the first port 12 and the second port 14 If measuring signals are output in a similar or the same measuring range, this short circuit can not be determined by means of the plausibility check or a check of the validity of the measured values. This is due to the fact that with similar or identical measuring ranges, similar or equal limits are set for the plausibility check.

In conventional operation of the sensor, the sensor typically provides a voltage in the range of 0.5 volts to 4.5 volts as first and second sense signals. In the event of a short circuit between the first output terminal and the second output terminal, the voltages of the first and second measurement signals are equal to each other. They do not leave the range from 0.5 volts to 4.5 volts.

Now referring to 2 the short-circuit verification method according to the invention will be explained. Carrying out the short-circuit verification method according to the invention in the control unit 30 occurs during a period in which the first and the second measurement signal of the sensor 10 from the control unit 30 not needed (step F). In particular, the measuring signals of the sensor 10 during this period is not required for use in the stability control system. The measuring signals of the sensor 10 become especially during a start or shutdown of an internal combustion engine of the motor vehicle is not needed. At these times, the motor vehicle has usually already come to a standstill, so that the stability control system of the motor vehicle does not respond to measuring signals of the sensor 10 instructed. Therefore, it is first determined in step F, whether a start or a shutdown of the internal combustion engine of the motor vehicle is present or any other period in the measurement signals of the sensor 10 not needed in the control unit.

To further improve the short circuit verification method, the sensor 10 additionally be brought into a state in which it outputs definable measurement signals. For example, the sensor 10 placed in a state in which at both output terminals 12 . 14 0 volts or 2.5 volts.

Subsequently, in step A, the first voltage is applied to the first output terminal 12 as explained above. The first voltage is from the control unit 30 by means of the A / D converter 40 at the first entrance 32 the control unit 30 imprinted, which is thus used as an output. Accordingly, the first output port becomes 12 of the sensor 10 used as input for a signal. Accordingly, the first input 32 the control unit 30 used as output. As a first voltage, the first line is connected to the ground GND, so that the first voltage is 0 volts.

In step B, after or at the same time as step A, it is checked whether one at the second port 14 is equal to the first signal below a predetermined first limit value with respect to the first voltage of 0 volts. For this purpose, the first signal at the second input 34 the control unit 30 recorded and compared with the predetermined first limit. In particular, when 0 volts is used as the first voltage, the first threshold is slightly above 0 volts. The first limit value is therefore determined in particular so that temporal transient phenomena and tolerances of the sensor are taken into account. For example, if the sensor typically outputs measurement signals in a range of 0.5 volts to 4.5 volts, then the first limit may be within a range greater than 0 volts and less than 0.5 volts. Preferably, the first is. Limit between 0.2 volts and 0.3 volts.

Is by means of the control unit 30 found that from the second port 14 output measured signal drops continuously or is equal to or below the predetermined first limit, the method goes to step C. Otherwise, the process can be terminated at this point and the sensor 10 marked as OK to save testing time.

Was the second measurement signal of the second terminal 14 below or at the predetermined first threshold, in step C, the second voltage is applied to the first terminal 12 created. The second voltage is also across the first input 32 which is now used as output, from the control unit 30 created. In particular, the second voltage is a maximum permissible supply voltage V _{cc of} the sensor 10 , This is for example 5 volts.

Analogous to step B, it is checked in step D after or simultaneously with step C whether a at the second terminal 14 now applied second signal is equal to or above a predetermined second limit value with respect to the second voltage. The second predefinable limit is, for example, slightly below 5 volts when using 5 volts as the second voltage. In particular, the second limit value is set so that temporal transient phenomena and tolerances of the sensor are taken into account. For example, if the sensor typically outputs measurement signals in the range of 0.5 volts to 4.5 volts, then the second threshold may be within a range greater than 4.5 volts and less than 5 volts. Preferably, the second threshold is between 4.7 volts and 4.8 volts.

Is by means of the control unit 30 determined that after a predetermined waiting time of, for example, 1.4 ms, the measuring signal of the second terminal 14 has risen to 5 volts, will step in. E found that the sensor 10 is defective. This defect is in particular due to a short circuit between the adjacent terminals 12 . 14 of the sensor 10 founded. As an alternative to the use of waiting times, the detection of the first and second signals present at the second connection can also be carried out and evaluated online in the control unit. A prerequisite for online acquisition is that no transient effects are to be expected in the sensor. Alternatively, a temporal course of the transient events is at least predictable and flows into the first limit value and the second limit value. Also in this case an online registration can take place.

By means of the short circuit verification method according to the invention, a malfunction of a sensor due to a short circuit can be detected easily and quickly. In particular, a malfunction of the sensor can also be detected if a plausibility check of the measurement signals supplied by the sensor determines that the sensor would be in order.

LIST OF REFERENCE NUMBERS

10

sensor

12

first connection

14

second connection

20

first line

22

second line

30

control unit

32

first entrance

34

second entrance

40

A / D converter

50

short circuit

Claims (7)

Short circuit verification method of at least one sensor ( 10 ) with at least a first ( 12 ) and a second connection ( 14 ), which are adjacent to each other, while via the first port ( 12 ) a first measurement signal of the sensor ( 10 ) and the second port ( 14 ) a second measuring signal of the sensor ( 10 ), the method comprising the following steps: a) applying (A) a first voltage to the first terminal ( 12 ), then or at the same time b) Check (B), whether one at the second port ( 14 ) is equal to or below a predeterminable first limit value with respect to the first voltage, if yes, c) application of (C) a second voltage to the first terminal ( 12 ) and, then or at the same time d) checking (D) whether one at the second port ( 14 ) is equal to or above a predeterminable second limit with respect to the second voltage, if yes e) determining (B) that the sensor ( 10 ) is defective. Short-circuit verification method according to claim 1, whose first voltage is 0 V and whose second voltage corresponds to a maximum permissible supply voltage of the sensor. Short circuit verification method according to one of the preceding claims, while the first and the second outputable measuring signal is an analog measuring signal. Short-circuit verification method according to one of the preceding claims, while the sensor ( 10 ) is an at least biaxial acceleration sensor or a rotation rate sensor. Short-circuit verification method according to one of the preceding claims, which is provided in a control unit ( 30 ) of a motor vehicle while the first connection ( 12 ) of the sensor ( 10 ) via a first line ( 20 ) with a first input ( 32 ) of the control unit ( 30 ) and the second port ( 14 ) of the sensor ( 10 ) via a second line ( 22 ) with a second input ( 34 ) of the control unit ( 30 ), wherein the application of the first and the second voltage by means of the control unit ( 30 ) he follows. A short-circuit verification method according to claim 5, comprising the further step of: f) performing (F) the short-circuit verification process in the control unit (15) 30 ) during a period in which the first and the second measurement signal of the sensor ( 10 ) from the control unit ( 30 ) are not required, in particular during a start or shutdown of an internal combustion engine of the motor vehicle. Control unit ( 30 ) of a motor vehicle with a memory component in which a short-circuit verification method according to one of claims 1 to 6 is deposited.

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