DE102013102543B4 - Rotary encoder with low power consumption - Google Patents

Abstract

Device, which comprises the following: - a capacitive rotation sensor in the form of a capacitor (C), which comprises a first and a second contacting electrode (1, 2; 1 ', 2') electrically insulated therefrom, between which a capacitance is formed, which in Depending on a rotation angle of an actuator of the rotation sensor varies periodically, - a comparator (110) coupled to the capacitor (C), which has a drop between the first and the second contact electrode (1, 2; 1 ', 2') of the capacitor (C). Compares charging voltage with an upper and a lower threshold value and, based on a result of the comparison, outputs an output signal (115) at an output (111) of the comparator (110), - one between the first contacting electrode (1, 2; 1 ', 2' ) and the output (111) of the comparator (110) coupled resistor (R) and a counter (120) coupled to the output (111) of the comparator (110), the capacitor (C) further comprising a coupling electrode (3; 3 '; 3''), which is electrically insulated from the first and second contacting electrodes (1, 2) and is rotatable relative to them about an axis, the capacitance formed between the first and second contacting electrodes (1, 2). by turning the coupling electrode (3; 3'; 3'') can be changed about the axis, the coupling electrode (3; 3'; 3'') being arranged as an electrically conductive layer on a gear (30; 30'; 30''; 30'''), the first and second contacting electrodes (1, 2) are arranged on a circuit board (10; 10'), the counter (120), the resistor (R) and/or the comparator (110) also being arranged on the circuit board.

Description

Technical area

The present invention relates to a device, a valve arrangement and an electromechanical unit, each of which has a capacitive rotation sensor.

Background of the invention

Capacitive sensors are known from the prior art, which work based on the change in the capacitance of a capacitor. For example, from the DE 10 2009 019 172 A1 a capacitive rotation sensor is known, which has a rotor, a stator and an evaluation circuit. The rotor includes a non-rotationally symmetrical rotor disk with an electrically conductive coating. The stator ring also has four quadrants, with the capacity between two of the quadrants being determined. Furthermore, from the US 7,126,495 B2 a capacitive motion encoder is known, which has a stator and a rotor. The stator has four quadrants, each of which is supplied with its own supply or evaluation circuit.

The disadvantage of the approaches described is that a complex evaluation circuit is used to determine the position of an object, which therefore has an increased power requirement. However, especially in connection with so-called energy harvesting devices, which work without a central energy supply, it is desirable to be able to carry out position determination with the lowest possible power consumption.

Rotary encoders are, for example, from the WO 93/17 302 A1 , AT 398 844 B , DE 34 06 389 A1 , DE 28 51 336 C2 , US 7,023,221 B1 , DE 32 13 800 C2 , DE 199 31 809 A1 , DE 37 11 062 A1 and the DE 37 40 544 C2 known.

Brief outline of the invention

It is therefore the object of the invention to record a rotation variable, in particular a number of revolutions, an angular velocity, a number of revolutions and / or a number of revolutions within a time period with low power consumption, low hardware expenditure and a simple structure. This object is achieved by a device according to claim 1, a valve arrangement according to claim 16 and an electromechanical unit according to claim 17.

• - einen kapazitiven Drehsensor in Form eines Kondensators, welcher eine erste und eine davon elektrisch isolierte zweite Kontaktierelektrode umfasst, zwischen welchen eine Kapazität gebildet ist, welche in Abhängigkeit eines Drehwinkels eines Aktuators des Drehsensors periodisch variiert,
• - einen an den Kondensator gekoppelten Komparator, zum Beispiel einen Komparator mit Mitkopplung, vorzugsweise einen Schmitt-Trigger, welcher eine zwischen der ersten und der zweiten Kontaktierelektrode des Kondensators abfallende Ladespannung mit einem oberen und einem unteren Schwellenwert vergleicht und basierend auf einem Ergebnis des Vergleichs ein Ausgangssignal, insbesondere ein binäres Ausgangssignal, an einem Ausgang des Komparators ausgibt,
• - einen zwischen die erste Kontaktierelektrode und den Ausgang des Komparators gekoppelten Widerstand und
• - einen an den Ausgang des Komparators gekoppelten Zähler, wobei der Kondensator ferner eine Kopplungselektrode umfasst, welche von der ersten und der zweiten Kontaktierelektrode elektrisch isoliert ist und relativ zu diesen um eine Achse drehbar ist, wobei die zwischen der ersten und der zweiten Kontaktierelektrode gebildete Kapazität durch Drehen der Kopplungselektrode um die Achse veränderbar ist, wobei die Kopplungselektrode als elektrisch leitende Schicht auf einem Zahnrad angeordnet ist, wobei die erste und die zweite Kontaktierelektrode auf einer Leiterplatte angeordnet sind, wobei ferner der Zähler, der Widerstand und/oder der Komparator auf der Leiterplatte angeordnet sind.

In a first aspect, the invention provides a device comprising:

• - a capacitive rotation sensor in the form of a capacitor, which comprises a first and a second contacting electrode electrically insulated therefrom, between which a capacitance is formed which varies periodically depending on a rotation angle of an actuator of the rotation sensor,
• - a comparator coupled to the capacitor, for example a comparator with positive feedback, preferably a Schmitt trigger, which compares a charging voltage falling between the first and the second contact electrode of the capacitor with an upper and a lower threshold value and based on a result of the comparison Outputs an output signal, in particular a binary output signal, at an output of the comparator,
• - a resistor coupled between the first contacting electrode and the output of the comparator and
• - a counter coupled to the output of the comparator, the capacitor further comprising a coupling electrode which is electrically insulated from the first and the second contacting electrodes and is rotatable about an axis relative thereto, the capacitance formed between the first and the second contacting electrodes can be changed by rotating the coupling electrode about the axis, the coupling electrode being arranged as an electrically conductive layer on a gear, the first and the second contacting electrodes being arranged on a circuit board, the counter, the resistor and/or the comparator also being on the Circuit board are arranged.

The capacitor is first charged by the output of the comparator via the resistor until the charging voltage of the capacitor reaches the upper threshold value. At this point, the comparator “tips” so that the capacitor is then discharged through the resistor until the charging voltage reaches the lower threshold. At this point, the comparator “tips” again so that the capacitor is then charged again. In some embodiments, there is therefore a binary signal at the output of the comparator, which alternates between a higher and a lower output value. The frequency at which the comparator output changes depends on the capacitance of the capacitor. Since the capacitance of the capacitor in turn depends on the angle of rotation of the actuator of the rotation sensor, the frequency of the output signal of the comparator is a direct measure of the angle of rotation of the actuator. This can therefore be read from the count rate of the counter that is directly or indirectly coupled to the output of the comparator.

The counter is set up to count a number of positive and/or negative pulses of the binary output signal. In some embodiments, the counter triggers on positive and/or negative edges of the output signal.

According to one example, the capacitor further comprises a coupling electrode which is electrically insulated from the first and second contacting electrodes and is rotatable relative thereto about an axis, wherein the capacitance formed between the first and second contacting electrodes is increased by rotating the coupling electrode about the axis is changeable. In this embodiment, it is therefore not necessary to electrically contact the rotatably mounted part of the rotation sensor. Rather, the first and second contacting electrodes can be arranged statically. In some embodiments, the first and second contacting electrodes may be arranged on a common carrier part such as a printed circuit board, as described in detail below. The first and second contacting electrodes can be arranged next to one another. In some embodiments, the first and second contacting electrodes are separated from each other by a web and/or gap. The first and/or the second contacting electrode can have a meander shape in the area of the web or the gap. In particular, the first and second contacting electrodes can have an interlocking meandering shape in this area. In a particularly preferred embodiment, the coupling electrode is designed in such a way that the change in capacitance during one revolution shows an asymmetrical course, so that the direction of rotation can be determined from this.

In some examples, the first and second contacting electrodes are arranged on a stator. The coupling electrode can be arranged on a rotor. In some embodiments, the capacitive rotation sensor is integrated into an electric motor. The coupling electrode of the capacitive rotation sensor can be rotationally coupled to a rotor of the electric motor. The first and second contacting electrodes can be firmly arranged on a stator of the electric motor or firmly connected to it.

In some embodiments, the first and second contacting electrodes may be formed from a conductive layer of a circuit board. This enables the contacting electrodes to be produced using known techniques for processing a circuit board. As will be described in detail below, further components of the device, such as the comparator and/or the resistor, can also be arranged on the circuit board.

The coupling electrode can have at least one eccentricity with respect to the axis. This can be achieved, for example, in that the coupling electrode has a circular shape, but the axis is not located in the center of the circular shape. In some embodiments, the coupling electrode has more than one eccentricity with respect to the axis, in particular two, three, four, six or eight eccentricities. An eccentricity occurs, for example, when the distance between the circumferential line of the coupling electrode and the axis reaches a maximum depending on the angle of rotation. In some embodiments, an eccentricity can be formed in that a distance between the circumferential line of the coupling electrode and the axis assumes a minimum depending on the angle of rotation.

In some embodiments, the first and second contacting electrodes may be equidistant from the axis. In some embodiments it can be provided that the first and second contacting electrodes are offset from one another by a certain angle with respect to the axis. The first and/or second contacting electrodes can have the shape of a circle segment.

In some examples, the capacitor includes a plurality of first and/or a plurality of second contacting electrodes. If there are several first or several second contacting electrodes, these can each be electrically connected to one another. In some embodiments, the plurality of first contacting electrodes may each have the same shape and/or be at the same distance from the axis. It can be provided that the plurality of second contacting electrodes each have the same shape and/or are at the same distance from the axis.

According to a particularly preferred embodiment, the coupling electrode has a distance in the axial direction of at least 1 mm from the first and second contacting electrodes. This enables a mechanical separation of the statically arranged parts of the rotation sensor from the rotating parts. This allows the mechanical robustness of the rotation sensor to be increased. In some embodiments, the coupling electrode has a distance of between 0.5 mm and 5 mm from the first and/or second contacting electrode in the axial direction, in particular between 1 mm and 3 mm and preferably between 1.5 mm and 2.5 mm.

In some embodiments, the coupling electrode is separated from the first and/or second contacting electrodes by an air gap. The coupling electrode can be separated from the first and/or second contacting electrode by an insulating layer. The insulation layer can be provided in particular on the coupling electrode and/or the first or second contacting electrode. In some embodiments, the coupling electrode can be separated from the first and/or the second contacting electrode by a housing part. The housing part can in particular form an underside of a housing section which at least partially surrounds the coupling electrode and optionally a carrier element on which the coupling electrode is arranged.

According to a preferred embodiment, the coupling electrode is arranged as an electrically conductive layer on a carrier element. The carrier element can be electrically insulating or electrically conductive. It is preferred that the coupling electrode is available by vapor deposition onto the carrier element. This enables the components to be manufactured easily.

The carrier element can be mounted on a shaft or molded onto a shaft. It is particularly preferred that the shaft runs through a circuit board on which the first and/or second contacting electrodes are arranged.

According to a preferred embodiment, the coupling electrode has an n-fold rotational symmetry with respect to the axis, where n is a positive and integer. In these embodiments, the counter result present on the counter has an increment of greater than one when the coupling electrode rotates completely around the axis. It is particularly preferred that the coupling electrode has a 4-fold, in particular an 8-fold and preferably a 16-fold rotational symmetry with respect to the axis. This enables a more precise determination of the speed.

In a preferred embodiment, the first and/or the second contacting electrode are arranged on a circuit board. Compared to other embodiments of the invention, in which the first and second contacting electrodes are arranged, for example, on different carrier parts, for example different circuit boards, this embodiment enables a simpler arrangement of the contacting electrodes and simpler production.

It is particularly preferred that the counter and/or the comparator are also arranged on the circuit board. Thus, only one circuit board is required to arrange multiple components, meaning that the device requires fewer components, can be made smaller and is easier to manufacture.

According to a preferred embodiment, at least one of the coupling electrodes is protected from the influence of electromagnetic interference fields by a shielding electrode. Particularly preferably, the shielding electrode is arranged above or below at least one of the contacting electrodes, so that the contacting electrode lies between the coupling electrode and the shielding electrode. In a preferred embodiment, the shielding electrode is designed as a grid and/or attached directly to the circuit board. The shielding electrode can be attached to the circuit board, for example by vapor deposition. The shielding electrode is spaced, for example, between 0.4 mm and 2 mm, in particular between 0.6 mm and 1.5 mm and preferably about 1 mm from the at least one contacting electrode.

In a preferred embodiment, the comparator has an oscillator circuit.

According to a preferred embodiment, the comparator is a Schmitt trigger and particularly preferably an inverting Schmitt trigger. The latter is particularly advantageous in embodiments in which the second contacting electrode, which is not coupled to the resistor, has a negative potential compared to the supply voltage. An inverting Schmitt trigger switches the signal output at the output to a negative value as soon as the charging voltage of the capacitor reaches the upper threshold value. This causes the first contacting electrode to be pulled to a low level via the resistance. If the second contacting electrode is also at the low level, the capacitor is thus discharged. As soon as the charging voltage of the capacitor reaches the lower threshold value, the inverting Schmitt trigger switches the output to a high level, which is also applied to the first contacting electrode of the capacitor via the resistor. The capacitor is thus recharged. Using a Schmitt trigger as a comparator has the advantage that all essential components of the oscillator circuit are already present in typical microcontrollers.

In other embodiments, instead of a Schmitt trigger, another oscillator circuit can be used to determine the capacity, in which the output signal is im Essentially depends on the capacity of an oscillating member. However, instead of using an oscillator circuit, the capacitance can also be measured in a different way in order to realize the position measurement.

Without restricting the invention, it will be described below using the preferred embodiments with an inverting Schmitt trigger as a comparator for determining capacity.

According to a preferred embodiment, the second contacting electrode is at an electrical potential that is constant over time. This results in a simpler connection between the counting result present on the counter and the angle of rotation of the actuator, without the effect of a time-varying reference potential having to be taken into account. The second contacting electrode can in particular be grounded. For example, the second contacting electrode can be on the ground of a motor control to which the device is coupled or which is integrated into the device.

It is particularly preferred that the comparator switches the output to the electrical potential that is constant over time when the charging voltage of the capacitor exceeds the upper threshold value. In these embodiments, the output of the comparator has the same electrical potential as the second contacting electrode when the charging voltage of the capacitor exceeds the upper threshold. The capacitor is thus discharged via the resistor.

According to a preferred embodiment, the capacitive rotation sensor has more than two contacting electrodes and the contacting electrodes are at at least three different electrical potentials. The comparator may, in some embodiments, switch the output to a lower electrical potential when the charging voltage of the capacitor exceeds the upper threshold.

According to a preferred embodiment, the device further comprises a signal generator for generating a pulsed signal, which is coupled to the counter, the counter counting pulses of the output signal of the comparator during each pulse of the pulsed signal. The pulsed signal can in particular be coupled to an activation input of the counter. In particular, in some embodiments, the signal generator may generate a pulsed signal with a constant frequency and a constant duty cycle. The counter counts the pulses of the comparator's output signal only during a pulse of the signal generator. This makes it possible for a change in the frequency of the output signal of the comparator and thus a change in the angle of rotation of the actuator of the rotation sensor to be detected. It can be provided that the signal generator is programmable in order to specify a frequency and/or a clock ratio of the pulsed signal.

In some embodiments, the counter resets a counter result at the end of a cycle of the signal generator's pulsed signal. The counting result of the counter present at the end of a cycle of the pulsed signal is therefore a measure of the average counting rate during the pulse and thus of the capacitance of the capacitor. The count rate is approximately inversely proportional to the capacitance of the capacitor. The counting result at the end of the cycle is therefore a measure of the angle of rotation of the actuator.

In some embodiments, the signal generator generates the pulsed signal with a frequency between 100 Hz and 100 kHz, in particular between 200 Hz and 50 kHz and preferably between 500 Hz and 10 kHz. In a particularly preferred embodiment, the signal generator generates the pulsed signal with a frequency of approximately 1 kHz. In some embodiments, the signal generator generates the pulsed signal with a pulse width ratio of between 0.1 and 0.9, in particular between 0.3 and 0.7 and preferably between 0.4 and 0.6. It is particularly preferred that the signal generator generates the pulsed signal with a pulse width ratio of approximately 0.5.

According to a preferred embodiment, the capacitive rotation sensor, the resistance and the upper and lower thresholds are designed such that the output signal at the output of the comparator has a frequency between 5 kHz and 10 MHz, in particular between 50 kHz and 5 MHz, preferably between 100 kHz and 10 MHz and particularly preferably between 500 kHz and 2 MHz. The ratio of the frequency of the pulsed signal from the signal generator to a mean frequency at the output of the comparator can be less than 1:50. In some embodiments, the ratio may be less than 1:100, in particular less than 1:500 and preferably less than 1:1000. The supply voltage of the comparator is, for example, between 1.8 V and 5.5 V, preferably between 2.5 V and 3.3 V. In some embodiments, the comparator has an input hysteresis so that a high logic level is set when the input voltage is, for example, less than a lower voltage value, for example 30% of the supply voltage, while a low logic level is set if the input voltage is, for example, above an upper voltage voltage value, which can correspond to, for example, 70% of the supply voltage.

According to a preferred embodiment, the device further has a transmitter coupled to the counter and/or an interface coupled to the counter, for example with a transmitter for transmitting a counting result or a counting rate of the counter. In some embodiments, the interface can be set up to transmit the counting result in a wired manner, in particular in a wired manner and/or wirelessly. The interface can in particular be set up to transmit the counting result via a radio interface and/or an optical interface, for example an IR interface, using a transmitter. In some embodiments, the interface or the transmitter transmits the counting result at a specified time within one cycle of the pulsed signal of the signal generator and/or after k cycles of the pulsed signal have elapsed. These embodiments make it possible for the counting result of the counter and thus the capacitance of the capacitor, which is a measure of the angle of rotation of the actuator, to be transmitted to an external receiver.

In some embodiments, the device further comprises a thermoelectric element and/or a photoelectric element for electrically supplying the comparator, the counter, the signal generator and/or the transmitter. This enables a power supply to the components that is independent of a mains supply.

In some embodiments, the device further comprises a memory coupled to an output of the counter, which is designed to store one or more counting results. In particular, the counter and/or the memory can be set up to store the count result of the counter periodically in the memory, for example with the period of the pulsed signal of the signal generator. This makes it possible to access previous counting results. Furthermore, the device can have evaluation logic in order to form differences between successive counting results stored in the memory in order to determine a rotational speed and/or rotational speed of the actuator. By forming the difference, a change over time in the average counting rate of the counter and thus in the capacity is determined. Such a change in capacity over time indicates a change in the angle of rotation of the actuator.

In a further aspect, the invention provides a valve arrangement, in particular with a heating valve, which has a device of the type described for determining a valve position. In this way, the valve position of, for example, a heating valve with low power consumption can be read and, for example, transmitted to a receiver.

In a further aspect, the invention provides an electromechanical unit with a motor and a device of the type described, wherein a rotor of the motor is coupled to the actuator of the rotation sensor. In this way, the rotor position of the motor can be read. The electromechanical unit can in particular be designed as a valve arrangement, for example as a heating valve arrangement. The actuator of the rotation sensor can be, for example, a gear that is connected to a drive shaft of an electric motor as part of a transmission. In the case of a heating valve arrangement or a heating valve adjuster, the electric motor drives an output shaft via the gearbox for adjusting a heating valve.

According to a preferred embodiment, the electromechanical unit further has an electrical motor control, with at least part of the motor control as well as the comparator and the counter being arranged on a circuit board. In addition, in some embodiments, the first and/or second contacting electrode of the rotation sensor can also be arranged on the circuit board. This enables a compact arrangement of the components.

• 1a einen Ausschnitt einer Vorrichtung,
• 1b eine Explosionszeichnung der Vorrichtung nach 1a,
• 1c die Darstellung der Vorrichtung nach 1a,b in einer Ansicht von schräg unten,
• 2a eine Explosionszeichnung eines Trägerelements mit einer Kopplungselektrode,
• 2b das Trägerelement und die Kopplungselektrode nach 2a in einer Ansicht von unten,
• 2c eine Explosionszeichnung eines Trägerelements mit einer alternativ ausgestalteten Kopplungselektrode,
• 2d das Trägerelement und die Kopplungselektrode nach 2c in einer Ansicht von unten,
• 3a eine Explosionszeichnung eines Ausschnitts einer Vorrichtung von schräg unten,
• 3b die Explosionszeichnung nach 3a in einer Ansicht von schräg oben,
• 4a eine Explosionszeichnung eines Trägerelements mit einer Kopplungselektrode von schräg oben,
• 4b eine Explosionszeichnung des Trägerelements mit Kopplungselektrode gemäß 4a von schräg unten
• 5 die Veränderung der Kapazität des Kondensators in Abhängigkeit von dem Drehwinkel des Aktuators,
• 6 eine Schaltskizze der Vorrichtung,
• 7 Zählergebnisse des Zählers über mehrere Pulse eines Signalgenerators bei sich veränderndem Drehwinkel und
• 8a,b eine Vorrichtung gemäß einer weiteren Ausführungsform.

Further features and advantages will become clear from the following description of preferred embodiments. In it shows

• 1a a section of a device,
• 1b an exploded view of the device 1a ,
• 1c the representation of the device 1a,b in a view diagonally from below,
• 2a an exploded view of a carrier element with a coupling electrode,
• 2 B the carrier element and the coupling electrode 2a in a view from below,
• 2c an exploded drawing of a carrier element with an alternatively designed coupling electrode,
• 2d the carrier element and the coupling electrode 2c in a view from below,
• 3a an exploded drawing of a section of a device diagonally from below,
• 3b the exploded view 3a in a view diagonally from above,
• 4a an exploded view of a carrier element with a coupling electrode diagonally from above,
• 4b an exploded view of the carrier element with coupling electrode 4a from diagonally below
• 5 the change in the capacitance of the capacitor depending on the angle of rotation of the actuator,
• 6 a circuit diagram of the device,
• 7 Counting results of the counter over several pulses of a signal generator with changing angle of rotation and
• 8a,b a device according to a further embodiment.

In the 1a - c and 2a, b A capacitive rotation sensor is shown. This has a support element, which is designed as a circuit board 10 (see Fig. 1a and 1b) . Contacting electrodes 2, 11, 12 are arranged on the circuit board 10. The contacting electrodes 11 and 12 can be conductively connected to one another to form an overall electrode 1, which is electrically insulated from the contacting electrode 2. An opening 16 is provided in the circuit board 10 between the contacting electrodes in order to accommodate an axle element 4. The axle element 4 runs perpendicular to the circuit board 10. A support element 30, which is designed as a gear, is arranged on the axle element 4. The carrier element 30 has a larger radius in an area adjacent to the circuit board 10 and springs back to a smaller radius in an area spaced from the circuit board 10. In both areas, the carrier element 30 is equipped with teeth on its circumference. Furthermore, another gear wheel 6 is provided, which has teeth on its outside. The teeth of the gear wheel 6 engage in the teeth of the carrier element 30. In some embodiments, the gear 6 may be coupled directly or indirectly to an electric motor. In this way, the movement of the rotor of the electric motor is transmitted to the carrier element 30.

On the underside of the carrier element 30 there is a coupling electrode 3 (see Fig. 1c , 2a and 2 B) . The coupling electrode 3 is cross-shaped and is arranged centered on the underside of the carrier element 30. The coupling electrode 3 thus has a 4-fold rotational symmetry with four eccentricities with respect to the axis of rotation defined by the axis element 4.

During a rotation of the carrier element 30, a spatial overlap between the coupling electrode 3 and the contacting electrodes 11, 12 and 2 changes. Due to the non-rotationally symmetrical arrangement of the coupling electrode 3 with respect to the axis defined by the axis element 4, the position between the interconnected electrodes 11, 12 and the contacting electrode 2 formed capacity. The course of the capacitance as a function of the angle of rotation of the carrier element 30 is periodic in the angle of rotation of the carrier element 30 with a period of 90°. In a preferred embodiment of the invention, the two contacting electrodes 11 and 12 are not connected to one another to form an overall electrode, but are contacted individually. The contacting electrodes 11 and 12 are set to different electrical potentials, so that the direction of rotation can also be detected using a suitable counter electrode via the change in capacitance. In another embodiment of the invention, the two contacting electrodes 11, 12 can be set to a common electrical potential, but have different capacities, in that their area, shape and / or their axial distance (perpendicular to the plane of the circuit board) to the counter electrode 3 are chosen differently. For example, the circuit board can have a small step on which one of the two contacting electrodes 11, 12 is applied. This describes further embodiments of the invention with which detection of the direction of rotation via a change in capacitance is possible.

In the example of 1a until 1c There is a housing base 51 between the circuit board 10 and the carrier element 30, which, analogous to the opening 16, has a further opening through which the axle element 4 can be guided. However, it can also be advantageous to integrate the axle mount into the housing base 51, so that no opening in the housing and / or in the circuit board 10 is necessary, which results in several advantages. On the one hand, the housing can then be better sealed against moisture or dirt and, on the other hand, smaller wall thicknesses can be selected for both the circuit board 10 and the housing base 51, since the construction is not weakened by openings. As a result, the distance between contacting electrodes 2, 11, 12 and coupling electrode 3 can be reduced and thus an increase in capacity can be achieved. It is also conceivable that the carrier element 30 rests on the housing base 51. Placing the housing base 51 between the electrodes applied to the circuit board 10 and the carrier element 30 has the advantage The advantage is that by choosing a suitable material, a dielectric with a high dielectric constant ε _r can be used, so that the capacity of the capacitors formed by the electrodes can be increased further (ε _r > 1) than with air as the dielectric (ε _r ≈ 1) would be possible.

A further, optional but advantageous embodiment is provided by attaching a shielding electrode 13. These in 1c The shielding electrode 13 shown is preferably attached below the circuit board 51, opposite one or more of the contacting electrodes 2, 11, 12, and can, for example, be vapor-deposited directly onto the circuit board 51. In the example, the shielding electrode 13 is designed as a lattice structure and is provided with openings which are arranged correspondingly to the openings of the circuit board 10. Of course, the shielding electrode can also have a different geometry in other designs.

An example of a coupling electrode with 2-fold rotational symmetry is shown in Figures 2c and 2d shown. The coupling electrode 3 'shown there can alternatively be used in the 2a and 2 B coupling electrode 3 shown can be used.

The 3a and b show a section of a device according to a further embodiment. A circuit board 10' is provided, on which a first contacting electrode 1' is located. The contacting electrode 1' was made from a conductive layer located on the circuit board 10'. The first contacting electrode 1' is designed as a segment of a circular ring. In the center of the circular ring there is an opening 16' in the circuit board 10'. The opening 16 'accommodates one end of an axle element 4', on which there is a support element 30' similar to the support element 30 in the 1 and 2 illustrated embodiment is arranged. The carrier element 30' is designed as a gear. There is a second contacting electrode 2' on the underside of the carrier element 30'. The second contacting electrode 2' runs halfway around the axle element 4', but is not designed to be rotationally symmetrical. As the carrier element 30' rotates about the axis defined by the axle element 4', a spatial overlap between the first contacting electrode 1' and the second contacting electrode 2' changes. This changes a capacitance formed between the contacting electrodes 1' and 2'. In order to be able to detect this change in capacity, both contacting electrodes 1', 2' are electrically contacted to the outside. In order to be able to contact the second contacting electrode 2', the carrier element 30' is further formed from an electrically conductive material or the second contacting electrode 2' is electrically connected to the shaft via a conductor track and a sliding contact, the shaft itself also being made from a conductive material , for example made of a metal. The contacting electrode 2 'from the 3a and 3b can of course also be used as a counter electrode, analogous to the counter electrode 3 from the 3a and 3b , can be used in conjunction with two or more contacting electrodes. For example, it can be used with the in 1b printed circuit board 10 shown and the electrodes 2, 11 and 12 applied thereto are combined. Also in the example of 3a For electromagnetic shielding, the circuit board 10' is provided with a shielding electrode 13', which in this preferred embodiment shields the entire electrode arrangement.

In the 4a and 4b a carrier element 30" is shown according to a further embodiment, which differs from the carrier elements 30 and 30' in the shape of the applied electrode. The carrier element 30" is constructed as a concentric arrangement of two gears with different radii. On the underside of the gear with a larger radius there is an electrode 3". The electrode 3" surrounds a central axis of the carrier element 30" in a crescent shape. The electrode 3", for example, spans an angle of approximately 180° around the central axis. In some embodiments, it can be provided that the electrode 3" is used as a coupling electrode in order to capacitively couple a first and a second contacting electrode to one another. The crescent-shaped coupling electrode 3" has the advantage that it has one or more contacting electrodes during rotation causes an asymmetrical change in capacitance, allowing the direction of rotation to be determined easily and reliably. Of course, other shapes for the coupling electrode are also possible in order to achieve an asymmetrical capacitance curve. However, in some embodiments it can also be provided that a crescent-shaped electrode, such as that in the 4a and 4b Electrode 3" shown is designed as the first or second contacting electrode of a capacitor. For this purpose, the potential of the electrode 3" can be electrically routed to the outside.

5 illustrates an exemplary course of a capacitance of a capacitive rotation sensor depending on a rotation angle of an actuator of the rotation sensor. The based on the 5 The illustrated capacitive rotation sensor is based on a rectangular contacting electrode, which is arranged on a stator, and a further rectangular contacting electrode, which is arranged on a rotor. In 5 is the course of the at The capacity formed by the contacting electrodes is shown as a function of a rotation angle α of the rotor. The in 5 The capacity curve C / C _max shown is standardized to a maximum capacity C _max .

6 shows a circuit diagram of a device according to an embodiment. The capacitive rotary sensor is shown as a capacitor C with a variable capacity. As a rotation sensor, for example, the ones in the 1 until 4 shown arrangements can be used. A first contacting electrode of the capacitor C is connected to the input of an inverting Schmitt trigger 110, while a second contacting electrode of the capacitor C is connected to ground. The designation of a first and a second contacting electrode introduced in this context does not necessarily correspond to the definition used above in connection with the description of rotation sensors. For example, one of the contacting electrodes 1, 2, 1 ', 2" can be grounded and the other contacting electrode of the sensor can be connected to the input of the Schmitt trigger. An output 111 of the inverting Schmitt trigger is also via a resistor R connected to the first contact electrode of the capacitor C. Furthermore, the output 111 of the Schmitt trigger 110 is connected to a counting input 121 of a counter 120. The counter 120 also has an activation input (enable - EN) 122, which is connected to a signal generator of the device ( not shown). one period of signal 125, counter 120 resets the counting result to zero.

To illustrate how the device works, it is first assumed that the output 111 of the Schmitt trigger shows a high level. This is also applied to the first contacting electrode of the capacitor C via the resistor R, so that the capacitor C is charged via the resistor R. As soon as the charging voltage measured between the first and second contact electrodes of the capacitor exceeds a predefined upper threshold, the inverting Schmitt trigger 110 switches its output 111 to a low level. This is also applied to the first contacting electrode of the capacitor C via the resistor R. The capacitor C is now discharged again via the resistor R. As soon as the charging voltage of the capacitor C falls below a predetermined lower threshold, the inverting Schmitt trigger 110 switches its output 111 to a high level and the capacitor C is charged again. The repeated charging and discharging of the capacitor C causes the output of the Schmitt trigger to flip between high and low levels, resulting in the binary output signal of the Schmitt trigger 110 shown with reference number 115.

The period of the output signal 115 depends on the capacity of the capacitor C, the resistor R and the upper and lower threshold values of the Schmitt trigger 110. Of these influencing variables, only the capacity of the capacitor C can be changed. The larger the capacity of the capacitor C, the longer the time period required to charge or discharge the capacitor C. The period of the output signal 115 of the Schmitt trigger 110 therefore also depends on the capacitance of the capacitor C. Since the capacitance of the capacitor C in turn depends on a rotation angle of the actuator of the rotation sensor, the frequency of the signal 115 output at the output 111 of the Schmitt trigger 110 is a measure of the rotation angle of the actuator.

The output signal 115 of the Schmitt trigger 110 is also coupled to the counting input 121 of the counter 120. The counter 120 counts the positive pulses in the output signal 115 of the Schmitt trigger 110. In other embodiments, the counter 120 triggers on negative pulses or on positive or negative edges in the output signal 115.

The counter 120 counts the pulses present in the signal 115 at the output 111 of the Schmitt trigger 110 only during a pulse in the signal 125 at the activation input 122 of the counter 120. During the rest of a cycle of the signal 125, i.e. when none Pulse is present, the counter result of the counter 120 remains constant. This counter result indicates an average count rate of the counter 120 during the previous pulse and thus a frequency of the signal 115. In some embodiments, it may be provided that the device transmits this constant counter result using a transmitter (not shown) while the signal 125 does not show a pulse. At the end of each cycle of signal 125, i.e. at the beginning of the next pulse, the counter result of the counter is set to zero.

7 illustrates by way of example the course of a counting result of the counter 120 over nine consecutive pulses of the pulsed signal 125, ie depending on the time t, while the angle of rotation of the actuator is changed. The pulses in the output signal 115 of the Schmitt trigger 110 are each counted over a pulse width of the pulsed signal 125 generated by the signal generator. This can be provided, for example be that the pulsed signal 125 has a frequency of 1 kHz, while the frequency of the output signal 115 of the Schmitt trigger 110 is in the range of approximately 1 MHz. The exact value of the frequency of the output signal 115 depends, as described above, on the current capacitance of the capacitor C and thus on the angle of rotation of the actuator. As in 7 shown, there are therefore a different number of pulses of the output signal 115 of the Schmitt trigger 110 per pulse of the pulsed signal 125. The number of pulses of the output signal 115 is approximately reciprocally proportional to the capacity of the capacitor C. The in 7 The counting results shown per pulse of the pulsed signal 125 thus represent average values of the counting rates on the counter 120. In order to enable an exact determination of the position of the actuator, it is advantageous that the frequency of the pulsed signal 125 is significantly lower than the frequency range in which the output signal 115 of the Schmitt trigger 110 moves. When using an asymmetrical coupling electrode, such as in the 4a and 4b is shown, there is the advantage that the approximately periodic course of the mean values of the count rates over time t within a period has an asymmetry (not shown), via which the direction of rotation can be easily determined.

In the 8a and 8b Another embodiment of the device is shown. A circuit board 10''' is provided, which has contacting electrodes (not shown). Furthermore, a carrier element 30''' arranged in a housing 5' is provided with a coupling electrode 3''. The carrier element 30''' is designed as a gear wheel, which is in engagement with another gear wheel 6'. The housing 5', in which the carrier element 30''' is arranged, has a base plate 51', which is located between the carrier element 30''' and the circuit board 10'''. In this way, the mechanical robustness of the arrangement is improved. In particular, the housing 5' can completely surround moving elements such as the carrier element 30''' and the gear wheel 6', so that no dirt or moisture can penetrate.

The ones in the 8a and 8b The device shown is designed as a valve actuator for a heater. The carrier element 30''' is part of a gear arrangement 8 driven by an electric motor 7. The electric motor drives a drive gear 6'', which transmits the force via the gear arrangement with the carrier element 30''' to a driven gear. The driven gear is then connected to an eccentric disk, which can be used to adjust the heating valve. For this purpose, the inner ring of a rolling bearing is arranged on the outer circumference of the eccentric disk. The outer circumference of the rolling bearing then acts via a transmission element on a valve pin of the heating valve so that it can be opened and closed. Such valves are usually provided with return springs, against whose force the electric motor has to work. In order to reduce the force required when adjusting the valve, it can therefore be advantageous to at least partially compensate for the restoring force of the valve using an additional spring. In the present exemplary embodiment, the spring is designed as a torsion spring, one leg of which is mounted on the housing of the heating valve actuator while the other leg presses against the roller bearing. For further details on the heating valve actuator see also the DE 102012102615 A1 , the content of which is expressly included in the present disclosure regarding the design of the valve actuator and its effect.

Further modifications of the illustrated embodiments are possible. For example, in some embodiments, another measuring device can be used to determine the capacity instead of an inverting Schmitt trigger. Alternatively or in addition to the described embodiments, the comparator, the counter and/or the signal generator of the device can be arranged on the same circuit board as the contacting electrodes. In some embodiments it can be provided that the device has a transmitter for transmitting a counting result of the counter. The coupling electrode or one of the contacting electrodes can be coupled to the rotor of a motor or a movable part of a valve.

Reference symbol list

1, 1', 2, 2'

Contacting electrode

10, 10', 10'''

Circuit board

11, 12,

Contacting electrode

13, 13'

shielding electrode

16, 16'

opening

3, 3', 3''

Coupling electrode

30, 30', 30'', 30'''

Support element

4, 4'

Axle element

5, 5'

Housing

51, 51'

base plate

6, 6'

gear wheel

110

comparator

111

Exit

115

signal

120

counter

121

Counting input

122

Activation input

125

signal

Claims (13)

Device comprising: - a capacitive rotation sensor in the form of a capacitor (C), which comprises a first and a second contacting electrode (1, 2; 1', 2') electrically insulated therefrom, between which a capacitance is formed, which depends on an angle of rotation of an actuator of the Rotary sensor varies periodically, - a comparator (110) coupled to the capacitor (C), which compares a charging voltage falling between the first and the second contacting electrodes (1, 2; 1', 2') of the capacitor (C) with an upper and a lower threshold value and based on a result of the comparison, outputs an output signal (115) at an output (111) of the comparator (110), - a resistor (R) coupled between the first contacting electrode (1, 2; 1', 2') and the output (111) of the comparator (110) and - a counter (120) coupled to the output (111) of the comparator (110), the capacitor (C) further comprising a coupling electrode (3; 3'; 3'') which is separated from the first and second contacting electrodes (1 , 2) is electrically insulated and can be rotated relative to it about an axis, the capacitance formed between the first and second contacting electrodes (1, 2) being changeable by rotating the coupling electrode (3; 3'; 3'') about the axis is, wherein the coupling electrode (3; 3'; 3'') is arranged as an electrically conductive layer on a gear (30; 30'; 30''; 30'''), wherein the first and second contacting electrodes (1, 2) are arranged on a circuit board (10; 10'), the counter (120), the resistor (R) and/or the comparator (110) also being arranged on the circuit board. Device according to Claim 1 , wherein the coupling electrode (3; 3';3'') has a distance in the axial direction of at least 1 mm from the first and second contacting electrodes (1, 2). Device according to Claim 1 or 2 , wherein the coupling electrode (3; 3';3'') is available by vapor deposition onto the gear (30; 30';30'';30'''). Device according to one of the Claims 1 until 3 , wherein the coupling electrode (3) has an n-fold rotational symmetry with respect to the axis, where n is a positive and integer. Device according to one of the preceding claims, wherein the comparator (110) comprises an oscillator circuit. Device according to one of the preceding claims, wherein the comparator (110) is an inverting Schmitt trigger. Device according to one of the preceding claims, wherein the second contacting electrode (1, 2; 1', 2') is at an electrical potential that is constant over time. Device according to one of the preceding claims, wherein the capacitive rotation sensor has more than two contacting electrodes (1, 2; 1', 2') and wherein the contacting electrodes are at at least three different electrical potentials. Device according to one of the preceding claims, wherein the comparator (110) switches the output (111) to a lower electrical potential when the charging voltage of the capacitor (C) exceeds the upper threshold value. Apparatus according to any one of the preceding claims, further comprising a signal generator for generating a pulsed signal (125) coupled to the counter (120), and wherein the counter (120) receives pulses of the output signal (115) of the comparator (110), respectively counts during a pulse of the pulsed signal (125). Device according to one of the preceding claims, further comprising an interface coupled to the counter (120) and/or a transmitter coupled to the counter (120) for transmitting a count result or a count rate of the counter (120). Valve arrangement, in particular with a heating valve, which has the device according to one of the preceding claims for determining a valve position. Electromechanical unit with a motor and the device according to one of the Claims 1 until 11 , wherein a rotor of the motor is coupled to the actuator of the rotation sensor.

Images