DE102018220852B4 - Signal transmission of a control device arrangement - Google Patents

Abstract

Control device arrangement (10), set up to generate a control signal (26), the control device arrangement (10) comprising: a control circuit (35); an evaluation electronics (37); an inductor (30), which is in series with the control circuit (35) and the Evaluation electronics (37) are connected and are set up to generate a magnetic field (31) when current flows through, the inductance (30) having an inductance value of less than or equal to 5 mH; anda magnetic sensor (25) which is designed to generate a control signal (26) at an output (19) of the control device arrangement (10) in response to the magnetic field (31).

Description

Field of invention

The invention relates to devices and methods for signal transmission. In particular, the invention relates to the generation of a control signal during level measurement and a control device arrangement.

background

To measure the level, field devices are used that have a control circuit, the control circuit comprising a sensor, in particular a level sensor. The field devices can be constructed in such a way that when a predefined condition is met, the field device sends a signal to evaluation electronics, which in turn controls a pump, for example.
The document DE 698 20 548 T2 describes a device for detecting errors in an electrical line of a vehicle.
The document DE 198 03 992 C2 describes an electromagnetic relay.
The document FR 2 268 347 A1 describes a relay for controlling circuit breakers.

Summary of the invention

It is the object of the invention to inform a user about the status of a field device.

This task is solved by the subject matter of the independent patent claims. Further developments of the invention result from the subclaims and the following description.

One aspect of the invention relates to a control device arrangement that is set up to generate a control signal. The control device arrangement can be, for example, a level measuring arrangement. The control device arrangement has a control circuit, for example in the form of a sensor, which detects and outputs a measurement signal. Furthermore, the control device arrangement has an inductance, which is connected in series with the control circuit and/or evaluation electronics and which is set up to generate a magnetic field when current flows through. Furthermore, the control device arrangement has a magnetic sensor which is set up to generate a control signal at an output of the control device arrangement in response to the magnetic field.

In the following, a control circuit can also be used more generally instead of a sensor. Likewise, a control device arrangement can generally be used instead of the level measuring arrangement.

For many types of field devices, low energy consumption can be important. The control device arrangement can have, as a sensor or part of the sensor, a high-frequency front end, ultrasonic front end or a laser front end. A signal that is generated by the sensor and evaluated by the evaluation electronics can, for example, be a “power on / power off” signal, which is generated, for example, by a relay or a transistor switch. The signal can also be a multi-level signal that has several voltage or current levels. The signal can also be an analog signal. The signal is used by the evaluation electronics, for example, to control a pump and/or valves, which can influence the fill level directly or indirectly.

An inductor is connected in series with the sensor. The inductance can be arranged between the sensor and the power supply or between ground and the sensor. The control device arrangement can include further components, for example evaluation electronics, which can be connected in series with the sensor and the inductor. The inductance can be designed as a discrete component, but it can also be designed, for example, as an SMD component (SMD: Surface-Mounted Device) and/or as a piece of a circuit board. The inductance generates a magnetic field depending on the current that flows through it.

The magnetic sensor is arranged near the inductor so that the magnetic sensor can detect the magnetic field generated by the inductor and convert it into a current or a voltage. This can be an analog or a digital signal. The magnetic sensor can also be an integrated chip that includes a digital communication interface. The current or voltage generated in this way can be passed directly to the output of the level measuring arrangement in order to generate the control signal at the output. The control signal generated in this way can also serve as a kind of “intermediate signal” from which the control signal routed to the output is generated. For this purpose, the intermediate signal can be routed, for example, to an amplifier, a processor, an OPV (operational amplifier) or an ADC (analog-digital converter), and the output signal of these components can then form the control signal.

The magnetic sensor can be separated from the inductance by an electrically insulating material. This material can be an electrically insulating fluid, such as air, nitrogen, inert gas, insulating oil (e.g. transformer oil or silicone oil) or a solid such as plastic or ceramic.

The control signal, which is available at the output of the level measuring arrangement, can be transmitted to a control system. The control signal can be galvanically isolated from the signal used by the evaluation electronics. In addition, this arrangement can be implemented very cost-effectively because only a few and inexpensive components are required for this solution. Realization is possible, for example, using a conductor track structure on a circuit board and a magnetosensitive component. It is particularly advantageous that the control signal generated in this way at the output only influences or burdens the signal generated by the sensor to a small extent. A low power consumption for generating the control signal can be advantageous, particularly for field devices. This device allows the original circuit arrangement and/or circuit dimensioning to be largely retained. The control signal at the output can advantageously be used, for example, to switch other devices, with the signal from the sensor only being electrically loaded to a small extent. The control signal informs a user about the status of the field device. The control signal can also be sent to a central monitoring system, so that a large number of level measuring devices can be monitored on this basis.

A further aspect of the invention relates to a control device arrangement, set up to generate a control signal which has a sensor and an inductor. The inductance is connected in parallel to the sensor. The control device arrangement can include further components, for example evaluation electronics, which can be connected in series with the sensor and the inductor. The inductor is designed to generate a magnetic field when current flows through it. Furthermore, the level measuring device has a magnetic sensor which is set up to generate a control signal at an output of the level measuring device in response to the magnetic field.

By running the sensor and inductance in parallel, a particularly low current load on the sensor can be achieved. Furthermore, the impedance at the output terminals of the sensor can be adjusted over a defined measuring range - if necessary using additional components.

In one embodiment, the control signal is set up to be transmitted from the output to a control system. The control system can be set up to monitor a large number of level measuring devices. It can also combine the individual level measuring devices into a production unit, which can be used to control a larger system, for example in the sense of “Industry 4.0”.

In one embodiment, the inductance is galvanically isolated from the magnetic sensor. This means, for example, that potential problems can be avoided even in larger systems. The galvanic isolation can also be adapted to special environments - e.g. safety-critical and/or explosive environments - through a selection of electrically insulating material and/or particularly voltage-resistant material and/or a sufficiently wide air gap between the inductance and magnetic sensor.

In one embodiment, the inductor is arranged in an explosion-proof environment and the magnetic sensor is arranged in a non-explosion-proof environment. This means that the level measuring arrangement can also be used in such critical environments - even if only the inductance side is adapted to the explosion-proof environment. The level measuring arrangement can advantageously also be used in environments that require process separation, for example if the level of a chemical process is to be monitored on the inductance side.

In one embodiment, the control circuit is arranged in an explosion-proof environment, and the inductor and the magnetic sensor are arranged in a non-explosion-proof environment. Furthermore, from the perspective of explosion protection, the inductance side is sufficiently separated from the magnetic sensor side. The connecting cables on the inductance side can therefore be routed into the explosion-proof area in which the control circuit is arranged.

In one embodiment, the inductor is designed as a discrete choke and/or as an unshielded choke and/or as a surface-mounted component, SMD, and/or as a coil printed on a circuit board. The design can depend on the operating environment and/or the design of the sensor. For example, if the sensor and possibly other components such as evaluation electronics are implemented on a module, then an SMD coil or a printed coil can be advantageous, for example in terms of costs and/or space requirements.

In one embodiment, the inductance has an inductance value of less than or equal to 5 mH, in particular less than or equal to 1 mH. Such a design results in, for example, only a small voltage drop on the measuring line. This allows, for example, the use of an amplifier kers on the measuring line must be avoided. This can be advantageous, for example, in terms of costs and/or power consumption.

In one embodiment, the magnetic sensor is designed as a Hall sensor. This makes the detection particularly sensitive. This can further facilitate space-saving implementation. For example, a discrete choke or a coil printed on a circuit board can be used as an inductor. The current flowing in the inductor creates a magnetic field and space-saving detection is carried out using the Hall sensor.

In one embodiment, the control signal at the output of the level measuring device is an analog signal. This is particularly advantageous if the level measuring device is to measure strongly and quickly fluctuating levels or if the levels have to be measured in a very differentiated manner.

In one embodiment, the magnetic sensor is designed as a Hall sensor with a comparator, in particular with an integrated comparator, and the control signal at the output of the level measuring device is a digital signal. Digital signals can be further processed particularly easily, e.g. collected, stored, compared and transmitted to other devices, in particular to servers and/or a cloud. Depending on the version of the level measuring device, the digital signal can comprise one bit (e.g. “level reached / not reached”) or several bits. The comparator can be implemented as a simple OPV or as an ADC.

In one embodiment, the level measuring device is set up to transmit the control signal from the output to the control system wirelessly, in particular via a Bluetooth protocol, via a Wireless Personal Area Network, WPAN, a Wireless LAN, WLAN, or LPWAN (Low Power Wide Area Network, e.g. LTE-Cat M1, Sigfox, LoRa, etc.). This means that the digital signal from the Hall sensor can be used, for example, to switch other devices or, for example, to transmit the switching signal to the cloud. This means that the switching status of the level measuring device could be monitored by a large number of stations.

In one embodiment, the sensor has a variable resistance which is connected in series with the inductance and/or the evaluation electronics. The variable resistance can be designed, for example, in the form of an ohmic potentiometer, for example a linear potentiometer. The variable resistance can also be formed using semiconductors, for example using one or more transistors. This makes it possible, for example, to record the fill level in a differentiated manner.

In one embodiment, the sensor has a switch which is connected in series with the inductance and/or the evaluation electronics. This makes it possible, for example, to set up very simple and/or robust devices that are designed, for example, to record information about “fill level reached/not reached”.

A further aspect of the invention relates to a measuring device, in particular a level measuring device, a level measuring device, a pressure measuring device or a flow measuring device. The measuring device has a sensor. Furthermore, the measuring device has an inductance, which is connected in series with or parallel to the sensor and which is set up to generate a magnetic field when current flows through. Furthermore, the measuring device has a magnetic sensor which is set up to generate a control signal at an output of the measuring device in response to the magnetic field. The measuring device can include additional components, for example evaluation electronics, which can be connected in series with the sensor and the inductance.

The design of the measuring device can have different measuring principles. The measuring device can be implemented, for example, as an impedance limit switch, as a vibration limit switch and/or as a radiometric measuring device. The above explanations apply analogously to the inductance, the magnetic sensor and the control signal.

• - Schließen eines Schalters an einem Sensor der Steuergerätanordnung, wenn der Sensor feststellt, dass ein vordefinierter Messwert erreicht und/oder überschritten wurde;
• - Erzeugen eines Magnetfelds, durch das Schließen des Schalters;
• - In Reaktion auf das Magnetfeld, Erzeugen eines ersten Wertes eines Steuersignals an einem Ausgang der Steuergerätanordnung.

A further aspect of the invention relates to a method for level measurement, limit level measurement, pressure measurement or flow measurement using a control device arrangement as described above and/or below. The procedure has the following steps:

• - Closing a switch on a sensor of the control device arrangement when the sensor detects that a predefined measured value has been reached and/or exceeded;
• - Generate a magnetic field by closing the switch;
• - In response to the magnetic field, generating a first value of a control signal at an output of the control device arrangement.

The first value can, for example, correspond to a “fill level reached” value.

• - Öffnen des Schalters an dem Sensor, wenn der Sensor feststellt, dass ein vordefinierter Messwert unterschritten wurde;
• - Abbau des Magnetfelds, durch das Öffnen des Schalters;
• - In Reaktion auf den Abbau des Magnetfelds, Erzeugen eines zweiten Wertes des Steuersignals an einem Ausgang der Steuergerätanordnung.

In one embodiment, the method further comprises these further steps:

• - Opening the switch on the sensor when the sensor detects that a predefined measured value has been undershot;
• - Reduction of the magnetic field by opening the switch;
• - In response to the reduction of the magnetic field, generating a second value of the control signal at an output of the control device arrangement.

The second value can, for example, correspond to a value “fill level not reached”.

For further clarification, the invention is described using the embodiments shown in the figures. These embodiments are only to be understood as an example and not as a limitation.

Short description of the characters

• 1 shows schematically a first embodiment of the present invention;
• 2 shows schematically a second embodiment of the present invention;
• 3 schematically shows a third embodiment of the present invention.

Detailed Description of Embodiments

1 shows a measuring arrangement 10, for example for a level measuring device 10, the measuring arrangement 10 having a sensor 35 and an inductance 30 in a first circuit 11. The measuring arrangement 10 also has an evaluation electronics 37. The inductance 30 is connected in series with the sensor 35 and the evaluation electronics 37; in the circuit shown, the inductance 30 is arranged between the sensor 35 and the evaluation electronics 37. The inductance 30 could also be arranged in a different order, e.g. between a voltage source U and the sensor 35 or between a ground GND and the evaluation electronics 37 or in another series. The sensor 35 has a variable resistor 33 so that the fill level in a device (not shown) can be measured continuously. The sensor 35 generates a signal 27, for example a current, by means of the variable resistor 33. The current can be evaluated, for example, by the evaluation electronics 37. For example, the evaluation electronics 37 can change the speed of a pump (not shown) and/or operate valves based on this signal. The inductance 30, which is connected in series with the sensor 35 and the evaluation electronics 37, is also flowed through by the current of the signal 27. If a current flows through, the inductance 30 generates a magnetic field 31. This can be detected by a magnetic sensor 25 and, in response to the magnetic field 31, generates a control signal 26 at an output 19 of the measuring arrangement 10. The control signal 26 is arranged in a second circuit 12, which is galvanically isolated from the first circuit 11. The galvanic isolation is represented by the reference number 23. The galvanic isolation can be implemented or supported by an electrically insulating material. The magnetic sensor 25 can, for example, be designed as a Hall sensor. The magnetic sensor 25 can have an amplifier. The magnetic sensor 25 can have an OPV or an ADC, so that the control signal 26 at the output 19 of the measuring arrangement 10 is a digital signal with a resolution of one or more bits. The control signal 26 can be sent to a control system 50, for example. The control system 50 can be arranged in a cloud (not shown).

2 resembles that 1 , whereby the same reference numbers have an analogous function as the corresponding reference numbers from 1 . The sensor 35 has a switch 34 so that the fill level in a device (not shown) can be continuously measured. The sensor 35 uses the switch 34 to generate a signal 27, for example a current, which is evaluated by the evaluation electronics 37. For example, the evaluation electronics 37 can switch a pump (not shown) on and off based on this signal. The inductor 30, which is connected in series with the sensor 35 and the evaluation electronics 37, is flowed through by the current of the signal 27 when the switch 34 is closed and thus generates a magnetic field 31. In response to the magnetic field 31, the magnetic sensor 25 generates the control signal 26 at an output 19 of the measuring arrangement 10. Because only the “on/off” signal is transmitted, the inductance 30 can be particularly small and/or the magnetic sensor 25 can be designed to be particularly insensitive.

3 schematically shows a third embodiment of the present invention. They have the same reference numbers as in 1 an analogous function to the corresponding reference numerals of 1 . A first circuit 11 has a sensor 35 and evaluation electronics 37, wherein the evaluation electronics 37 can be controlled by the sensor 35. An inductor 30 is connected in parallel to a variable resistor 33 of the sensor 35. The inductor 30 generates a magnetic field 31 when current flows through it. The strength of the magnetic field 31 depends on the voltage drop across the variable resistor 33. This circuit can be selected, for example, for reasons of impedance matching or a lower load on the sensor 35.

In addition, it should be noted that “comprising” and “having” do not exclude other elements or steps and the indefinite articles “a” or “an” do not exclude a plurality. It should also be noted that features or steps that refer to any of the above Embodiments that have been described can also be used in combination with other features or steps of other embodiments described above. Reference symbols in the claims are not to be regarded as limitations.

List of reference symbols

10

Measuring arrangement, measuring device

11

first circuit

12

second circuit

19

Exit

25

Magnetic sensor

26

Control signal

27

signal

30

inductance

31

Magnetic field

33

variable resistance

34

Switch

35

sensor

37

Evaluation electronics

50

Guidance system

Claims (17)

Control device arrangement (10), set up to generate a control signal (26), the control device arrangement (10) comprising: a control circuit (35); an evaluation electronics (37); an inductance (30), which is connected in series with the control circuit (35) and the evaluation electronics (37) and which is set up to generate a magnetic field (31) when current flows through, the inductance (30) having an inductance value of less than or equal to 5 mH; and a magnetic sensor (25), which is set up to generate a control signal (26) at an output (19) of the control device arrangement (10) in response to the magnetic field (31). Control device arrangement (10), set up to generate a control signal (26), the control device arrangement (10) comprising: a control circuit (35); an electronic evaluation system (37) which is connected in series with the control circuit (35); an inductor (30) which is connected in parallel to the control circuit (35) and which is designed to generate a magnetic field (31) when current flows through it, the inductor (30) having an inductance value of less than or equal to 5 mH; and a magnetic sensor (25), which is set up to generate a control signal (26) at an output (19) of the control device arrangement (10) in response to the magnetic field (31). Control unit arrangement (10). Claim 1 or 2 , wherein the control signal (26) is set up to be transmitted from the output (19) to a control system (50). Control device arrangement (10) according to one of the preceding claims, wherein the inductance (30) is galvanically isolated from the magnetic sensor (25). Control device arrangement (10) according to one of the preceding claims, wherein the inductor (30) is arranged in an explosion-proof environment and the magnetic sensor (25) is arranged in a non-explosion-proof environment. Control device arrangement (10) according to one of the preceding claims, wherein the control circuit (35) is arranged in an explosion-proof environment and the inductor (30) and the magnetic sensor (25) are arranged in a non-explosion-proof environment. Control device arrangement (10) according to one of the preceding claims, wherein the inductance (30) is designed as a discrete choke and/or as an unshielded choke and/or as a surface-mounted component, SMD, and/or as a coil printed on a circuit board. Control device arrangement (10) according to one of the preceding claims, wherein the inductance (30) has an inductance value of less than or equal to 1 mH. Control device arrangement (10) according to one of the preceding claims, wherein the magnetic sensor (25) is designed as a Hall sensor. Control device arrangement (10) according to one of the preceding claims, wherein the control signal (26) at the output (19) of the control device arrangement (10) is an analog signal. Control unit arrangement (10) according to one of the Claims 1 until 8th , wherein the magnetic sensor (25) is designed as a Hall sensor with a comparator, in particular with an integrated comparator, and wherein the control signal (26) at the output (19) of the control device arrangement (10) is a digital signal. Control device arrangement (10) according to one of the preceding claims, wherein the control device arrangement (10) is set up to control the control signal (26) from the output (19) to the control system (50) wirelessly, in particular via a Bluetooth protocol, via a Wireless Personal Area Network, WPAN, a Wireless LAN, WLAN, or Low Power Wide Area Network, LPWAN transmitted. Control device arrangement (10) according to one of the preceding claims, wherein the fill level sensor (35) has a variable resistor (33) which is connected in series with the inductor (30) and/or the evaluation electronics (37). Control device arrangement (10) according to one of the preceding claims, wherein the fill level sensor (35) has a switch (34) which is connected in series with the inductance (30) and/or the evaluation electronics (37). Level measuring device, limit level measuring device, pressure measuring device or flow measuring device, having a control device arrangement according to one of the preceding claims. Method for level measurement, limit level measurement, pressure measurement or flow measurement using a control device arrangement (10) according to one of Claims 1 until 14 , with the steps: - Closing a switch (34) on a sensor (35) of the control device arrangement (10) when the sensor (35) determines that a predefined measured value has been reached and / or exceeded; - Generating a magnetic field (31) by closing the switch (34); - In response to the magnetic field (31), generate a first value of a control signal (26) at an output (19) of the control device arrangement (10). Procedure according to Claim 16 , with the further steps: - opening the switch (34) on the sensor (35) when the sensor (35) detects that a predefined measured value has been undershot; - Reduction of the magnetic field (31) by opening the switch (34); - In response to the reduction of the magnetic field (31), generate a second value of the control signal (26) at an output (19) of the control device arrangement (10).

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