Method and device for supplying a sensor with a regulated sensor supply voltage

p0001The invention relates to a method and a device for supplying a sensor with a regulated sensor supply voltage.

p0002Sensors whose operating voltage or power supply voltage is lower than the voltage supplied by a voltage source, for example, be supplied via a voltage transformer. This makes it possible to connect the sensors to a network that performs a higher voltage than the operating voltage of the sensor is. In particular, the installation of sensors with an operating voltage of about 12V in a commercial vehicle, the vehicle electrical system, a higher voltage of about 24V, there is the danger of undetectable faults, as for example, caused by a short circuit in the wiring harness due Verquetschungen or by chafing with neighboring lines will. The misuse of the sensor can lead to the destruction or making false sensor signals.

p0003From the <patcit id="pcit0001" dnum="DE10127054A1"><text>DE 101 27 054 A1</text></patcit> discloses a generic method for the supply of a sensor with a regulated sensor supply voltage. The voltages generated by a supply module to be monitored in this process by ligaments and default values ​​for errors. For voltages which are in magnitude within the bands, and for voltages below these bands magnitude or exceed, in each case certain reporting signals are generated.

p0004The object of the invention is to provide a method and an apparatus of the aforementioned type, in which a supply voltage monitoring, with which the sensor is operated, is improved.

p0005This object is achieved in the method by the characterizing features of claim 1 and in the apparatus by the characterizing features of claim 4 or. 5

p0006In the invention, the sensor supply voltage, with which the sensor is operated, collected, analyzed and output immediately as a status signal. In this case, a first notification signal by means of an evaluation device which may be formed as a logic circuit, leave the case of exceeding a predetermined tuned to the sensor operating range of the sensor supply voltage.

p0007When below the predetermined operating range of the sensor supply a second alarm signal is issued. A third signal is generated if the sensor supply voltage lies within the tuned to the sensor operating range.

p0008The alarm signals are transmitted in a sensing line, which is provided between the evaluation device and a controller. The control unit evaluates the first two alarm signals for an error display and the third alarm signal for the continued operation or release operation of the voltage converter and sensor. The control unit can still function as a process controller which evaluates supplied by the sensor readings for process variables have.

p0009Due to the so obtained control of the sensor supply voltage, it is for example possible to bring 12V sensors in commercial vehicles with 24V electrical system used. Due to the achieved in the invention error detection, which can take place immediately at the output of the voltage converter, one achieves a reliable monitoring of the supply of the sensor and sensor operation. In addition, can be reached by means of a digital error signal to vary the sources of error. The first indication signal has a high level, especially the level of converter supply voltage of, for example, about 24V and the second status signal has a low level, especially as ground (0V) potential.

p0010The third alarm signal will be by means of a frequency generator between the two potentials of the first and the second signal, in particular between ground and the potential of the converter supply, clocked.

p0011Reference to the figures the invention is explained in more detail using an exemplary embodiment.

p0012It shows <dl id="dl0001"><dt>Fig. 1</dt><dd>a block diagram of an apparatus for supplying voltage to a sensor shaft cher an embodiment of the invention;</dd><dt>FIG. 2</dt><dd>in block diagram representation of a monitored voltage conversion device, which in the exemplary embodiment <figref idrefs="f0001">Fig. 1</figref> is used; and</dd><dt>Fig. 3</dt><dd>in block diagram a control unit, which in the exemplary embodiment <figref idrefs="f0001">Fig. 1</figref> is used.</dd></dl>

p0013In the <figref idrefs="f0001">Fig. 1</figref> is shown as a block diagram of the entire arrangement of the power supply for a sensor 17th The sensor 17 is used for example for the detection of process variables. In particular, the sensor 17 may in a commercial vehicle, such as a steering angle sensor in a steering column, are used. The time required for the operation of the sensor supply voltage is supplied via a supply line sensor 22nd By means of a monitoring voltage transformer device 10, which has a preferably electronically controlled voltage converter 12 (<figref idrefs="f0002">FIG. 2</figref>), Which DC voltage is placed at the output of the voltage converter 12 to the sensor 17 for operating the appropriate voltage. For example, the DC voltage has a value of 24V, which is common on board nets of commercial vehicles. This supply voltage is used to supply the voltage converter 12 and is supplied via a converter supply line 21st The voltage converter 12 regulates the DC voltage at 12V for operating the sensor 17th

p0014The sensor 17 is connected via a sensor signal line 26 or Messgrößensiganlleitung 26 with a control unit 13, which may also have the function of a process controller. The signals supplied by the sensor 17 via a sensor signal line 26 are used for process control, for example when driving a commercial vehicle. Due to the spatial separation of the sensor 17 from the controller 13 to interfere with the sensor supply can result. These disturbances can be caused by squeezing or fraying of lines with neighboring lines or by false jamming. This may for example mean that the sensor supply voltage in the sensor power supply line 22 by influences from the converter supply line 21 is too high and has for example a Störbeaufschlagung with about 20V. Furthermore, the sensor supply voltage can be in the line 22 is too low, for example at about 7V, be. Such disturbances may be caused 20 and the like due to line breaks in the converter supply line 21, a ground line.

p0015To detect such faults, is, as seen from the <figref idrefs="f0002">FIG. 2</figref> As can be seen, 12 an evaluation device 11, which has a Auswertelogikschaltung connected to the output of the voltage converter. For normal operation of the sensor 17, a range of supply voltage is provided, within which the sensor 17 is functioning properly. With a 12V sensor of this range, for example 9V to 14V can range.

p0016If due to a malfunction, the sensor supply voltage in the embodiment shown is> 14V, causes the evaluation logic at the switch output 27, which is implemented by an electronic switch, the voltage conversion means 10 in a connected to the switch output 27 signaling line 18, a first alarm signal with a constant high level, which preferably, the transducer voltage supply 21 (24 V) corresponds. If the sensor supply voltage 22 <9 is in the direction V, the switching output is 27 actuated by the evaluation unit 11 such that the signaling line 18 a second message signal to a low level, preferably ground (0 V) potential leads.

p0017If the sensor supply voltage is within the operating range of 9V to 14V, the control input of the switching output is 27 clocked by means of a frequency generator, so that the signaling line 18 is clocked, for example, at 30 Hz, between ground potential and the potential of the converter supply line 21 for a third notification signal. Using the evaluation logic described can be reached without the required software Sensor supply monitor.

p0018The sensing line 18 is connected to an evaluation device 16, which may be provided in the control unit 13 (<figref idrefs="f0003">Fig. 3</figref>). The reporting line 18 is guided through a pulldown resistor 29 to ground 20th The evaluation device 16 is preferably a digital evaluation logic for detection and discrimination of status signals delivered in the reporting line 18th The first alarm signal is supplied at too high a sensor power supply can provide an indication of a faulty sensor. In a memory 23 for troubleshooting this alarm signal is stored at a specific memory location.

p0019If the second alarm signal (low) is supplied via the signal line 18, this may indicate a fault in the line system, which serves to supply converter and / or sensor supply point. This signal is also stored in memory according to the 23rd If there is an error in the error memory 23, which is connected to a line connected to the control unit 13 Error display device 19, in response to the first or second alarm signal, an error message is given. Optionally, a lock- / enable circuit 24 for blocking the control device function which can be connected to the memory 23, are activated. If required, a switch can be opened 28 in the converter supply line 21 via a switching logic 25 so that the sensor operation is interrupted.

p0020If the signaling line 18, the third alarm signal is preferably clocked between the transducer supply potential and ground potential returns, this indicates the normal sensor operation. The control unit function is released or continued.

p0021It can also be checked whether the signaling line 18 is in good working condition. For this purpose, 17 tested the potential of the sensing line 18 by closing the switch 28 before connecting the sensor. If this potential is at ground (0 V) potential, is closed by releasing the control device function via the switching logic 25 of the switch 28 in the converter supply line 21st Here with correct sensor supply within the range of 9V to 14V, the signaling line 18 to the clocked alternating signal (third notification signal) is such that the control device function is enabled by the lock- / enable circuit 24th

p0022Each destruction of the signaling line 18, for example by a short to ground potential of the ground line 20, to an electrical outlet or by cable breakage leads to the switching of the clocked alternating signal at the corresponding constant potential of the first or the second signal. These are, as described above, evaluated in the control device. 13

p0023The analysis delivered by the sensing line 18 noise (first notification signal or second notification signal) may further for switching off the electronic stability program (ESP) lead. Moreover, the electronic brake system, an error message will be given. This is a further safety-critical function of the controller. 13

LIST OF REFERENCE NUMBERS

p0024<dl id="dl0002" compact="compact"><dt>10</dt><dd>Control voltage transformer device</dd><dt>11</dt><dd>evaluation</dd><dt>12</dt><dd>voltage converter</dd><dt>13</dt><dd>control unit</dd><dt>15</dt><dd>frequency generator</dd><dt>16</dt><dd>evaluation</dd><dt>17</dt><dd>sensor</dd><dt>18</dt><dd>signaling line</dd><dt>19</dt><dd>Error indicator</dd><dt>20</dt><dd>ground line</dd><dt>21</dt><dd>Converter supply line</dd><dt>22</dt><dd>Sensor supply line</dd><dt>23</dt><dd>Memory for error handling</dd><dt>24</dt><dd>Lock- / enable circuit</dd><dt>25</dt><dd>switching logic</dd><dt>26</dt><dd>Sensor signal line</dd><dt>27</dt><dd>Switching output, an electronic switch</dd><dt>28</dt><dd>switch</dd><dt>29</dt><dd>pulldown resistor</dd></dl>