DE102013102543A1 - Rotary encoder with low power consumption - Google Patents

Abstract

The present invention provides an apparatus comprising
A capacitive rotation sensor in the form of a capacitor which comprises a first and an electrically insulated second contacting electrode, between which a capacitance is formed which varies periodically in dependence on a rotational angle of an actuator of the rotary sensor,
A comparator coupled to the capacitor which compares a charging voltage dropped between the first and second contacting electrodes of the capacitor with upper and lower thresholds and outputs an output signal at an output of the comparator based on a result of the comparison;
A resistor coupled between the first contact electrode and the output of the comparator and
A counter coupled to the output of the comparator.

Description

Technical area

The present invention relates to a device, a valve assembly and an electromechanical unit, each having a capacitive rotation sensor.

Background of the invention

Capacitive sensors are known from the prior art, which operate on the basis of the change in the capacitance of a capacitor. For example, is 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 comprises a non-rotationally symmetrical rotor disk with an electrically conductive coating. The stator ring also has four quadrants, each determining the capacitance between two of the quadrants. Furthermore, from the US 7,126,495 B2 a capacitive motion encoder is known which comprises a stator and a rotor. The stator has four quadrants, each of which is supplied with its own supply or evaluation circuit.

A disadvantage of the described approaches is that an elaborate evaluation circuit is used to determine the position of an object, which thus has an increased power requirement. Especially in connection with so-called. Energy Harvesting facilities that operate without a central power supply, it is desirable to be able to perform a position determination with the lowest possible power consumption.

Brief outline of the invention

It is therefore the object of the invention to detect a rotational quantity, in particular a rotational speed, an angular speed, a number of revolutions and / or a number of revolutions within a period of time with low power consumption, low hardware complexity and simple construction. 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.

In a first aspect, the invention provides an apparatus comprising:

• A capacitive rotation sensor in the form of a capacitor which comprises a first and an electrically insulated second contacting electrode, between which a capacitance is formed which varies periodically in dependence on a rotational angle of an actuator of the rotary sensor,
• A comparator coupled to the capacitor, for example a positive feedback comparator, preferably a Schmitt trigger, which compares a charging voltage dropped between the first and second contacting electrodes of the capacitor with upper and lower threshold values and based on a result of the comparison Output signal, in particular a binary output signal, at an output of the comparator,
• A resistor coupled between the first contact electrode and the output of the comparator and
• A counter coupled to the output of the comparator.

In this case, 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. At this point, the comparator "tilts" so that the capacitor is subsequently discharged across the resistor until the charging voltage reaches the lower threshold. At this time, the comparator "flips" again, so that the capacitor is then recharged. Thus, in some embodiments, there is a binary signal at the output of the comparator which alternates between a higher and a lower output value. The frequency with which the output of the comparator tilts depends on the capacitance of the capacitor. Since the capacitance of the capacitor in turn depends on the rotational angle of the actuator of the rotary sensor, the frequency of the output signal of the comparator is a direct measure of the rotational angle of the actuator. This can thus be read from the count rate of the counter coupled directly or indirectly to the output of the comparator.

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

In some embodiments, the first and second contact electrodes are disposed on a stator. The coupling electrode may be arranged on a rotor. In some embodiments, the capacitive rotation sensor is integrated with an electric motor. In this case, the coupling electrode of the capacitive rotation sensor may be rotationally coupled to a rotor of the electric motor. The first and the second contacting electrode may be fixedly arranged on a stator of the electric motor or fixedly connected thereto.

In some embodiments, the first and second contact electrodes may be formed of a conductive layer of a printed circuit board. This enables the production of the contacting electrodes by means of known techniques for processing a printed circuit board. As will be described in detail below, further components of the device such as the comparator and / or the resistor may be arranged on the circuit board further.

The coupling electrode may have at least one eccentricity with respect to the axis. This can for example be achieved in that the coupling electrode has a circular shape, but the axis is not 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 is present, for example, when the distance of the circumferential line of the coupling electrode to the axis assumes a maximum in dependence on the angle of rotation. In some embodiments, an eccentricity may be formed by a minimum distance between the circumferential line of the coupling electrode and the axis as a function of the angle of rotation.

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

In some embodiments, the capacitor comprises a plurality of first and / or a plurality of second contact electrodes. In the case of a plurality of first or a plurality of second contacting electrodes, these can each be electrically connected to one another. In some embodiments, the plurality of first contact electrodes may each have a same shape and / or a same distance from the axis. It can be provided that the plurality of second contacting electrodes each have a same shape and / or have a same distance from the axis.

According to a particularly preferred embodiment, the coupling electrode to the first and second contacting electrode in each case a distance in the axial direction of at least 1 mm. This allows a mechanical separation of the statically arranged parts of the rotary sensor from the rotating parts. As a result, the mechanical robustness of the rotary sensor can be increased. In some embodiments, the coupling electrode to the first and / or second contacting electrode in the axial direction at a distance of between 0.5 mm and 5 mm, 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 electrode by an air gap. The coupling electrode may be separated from the first and / or second contacting electrode by an insulating layer. The insulating layer may be provided in particular on the coupling electrode and / or the first and second contacting electrode. In some embodiments, the coupling electrode may be separated from the first and / or the second contacting electrode by a housing part. In particular, the housing part may 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 may be electrically insulating or electrically conductive. It is preferable that the Coupling electrode is available by vapor deposition on the support element This allows easy production of the components.

The carrier element may be mounted on a shaft or formed on a shaft. It is particularly preferred that the shaft passes through a printed circuit board on which the first and / or second contacting electrode 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 number. In these embodiments, the counter result present on the counter has a gain greater than one upon complete rotation of the coupling electrode about the axis.

It is particularly preferred that the coupling electrode with respect to the axis has a 4-fold, in particular an 8-fold and preferably a 16-fold rotational symmetry. This allows a more accurate determination of the speed.

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

It is particularly preferred that further the counter and / or the comparator are arranged on the circuit board. Thus, only one circuit board is required for the arrangement of multiple components, whereby 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 by a shielding electrode against the influence of electromagnetic interference fields. 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 mounted directly on the circuit board. The shielding electrode can be mounted, for example by vapor deposition on the circuit board. The shielding electrode is, 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 contact electrode spaced.

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

According to a preferred embodiment, the comparator is a Schmitt trigger, and more 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 relative to the supply voltage. An inverting Schmitt trigger switches the output signal to a negative value as soon as the charging voltage of the capacitor reaches the upper threshold. As a result, the first contacting electrode is pulled to a low level via the resistor. When 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 via the resistor to the first contacting electrode of the capacitor. The capacitor is thus recharged. Using a Schmitt trigger as a comparator has the advantage that all the essential components of the oscillator circuit are already present in typical microcontrollers.

Instead of a Schmitt trigger, in other embodiments, another oscillator circuit can be used for determining the capacitance, in which the output signal is essentially dependent on the capacitance of a vibration element. However, it is also possible to measure the capacitance in another way instead of an oscillator circuit in order to realize the position measurement.

Without restricting the invention to this, it is described below with reference to 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 a time constant electrical potential. This results in a simpler relationship between the counting result present at the counter and the angle of rotation of the actuator, without having to take into account the effect of a temporally varying reference potential. The second contacting electrode may in particular be grounded. For example, the second contacting electrode may be located on the ground of a motor drive to which the device is coupled or which is integrated in the device.

It is particularly preferred that the comparator switches the output to the time-constant electrical potential when the charging voltage of the capacitor exceeds the upper threshold. 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 apparatus further comprises a signal generator for generating a pulsed signal coupled to the counter, the counter paying pulses of the output signal of the comparator during a pulse of the pulsed signal, respectively. The pulsed signal may in particular be coupled to an activation input of the counter. In particular, in some embodiments, the signal generator may generate a pulsed signal having a constant frequency and a constant duty cycle. The counter counts the pulses of the output signal of the comparator only during a pulse of the signal generator. This makes it possible that a change in the frequency of the output signal of the comparator and thus a change in the rotational angle of the actuator of the rotary sensor can 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 clock of the signal generator's pulsed signal. The counting result of the counter at the end of a pulse of the pulsed signal is thus a measure of the average counting rate during the pulse and thus for 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 thus a measure of the angle of rotation of the actuator.

In some embodiments, the signal generator generates the pulsed signal at a frequency between 100 Hz and 100 kHz, more preferably 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 at a frequency of about 1 kHz. In some embodiments, the signal generator generates the pulsed signal having a pulse width ratio of between 0.1 and 0.9, more preferably 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 about 0.5.

According to a preferred embodiment, the capacitive rotation sensor, the resistor and the upper and the lower threshold 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 more preferably between 500 kHz and 2 MHz. The ratio of the frequency of the pulsed signal of the signal generator to a mean frequency at the output of the comparator may be less than 1:50. In some embodiments, the ratio may be less than 1: 100, more preferably 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. The comparator has an input hysteresis in some embodiments, so that a high logic level is set when for example, the input voltage is less than a lower voltage value, e.g. B. 30% of the supply voltage is, while a low logic level is set when the input voltage is, for example, above an upper voltage value, the z. B. 70% of the supply voltage can correspond.

According to a preferred embodiment, the device further comprises a transmitter coupled to the counter and / or an interface coupled to the counter, for example with a transmitter for transmitting a count result or a count rate of the counter. In some embodiments, the interface may be configured to transmit the count result wired, in particular wired and / or wireless. 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, by means of a transmitter. In some embodiments, the interface, or the transmitter, transmits the count result each at a fixed time within one clock of the pulse generator signal and / or after k clocks of the pulsed signal, respectively. These embodiments make it possible that the counting result of the counter and thus the capacitance of the capacitor, which is a measure of the rotational angle of the actuator, can be transmitted to an external receiver.

In some embodiments, the device further comprises a thermoelectric element and / or a photoelectric element for the electrical supply of the comparator, the counter, the signal generator and / or the transmitter. This allows a power supply of the components independent of a mains supply.

In some embodiments, the apparatus further comprises a memory coupled to an output of the counter and configured to store one or more count results. In particular, the counter and / or the memory may be configured to store the counting result of the counter periodically, for example with the period of the pulsed signal of the signal generator in the memory. This makes it possible to resort to previous counting results. Further, the apparatus may include evaluation logic to form differences between successive count results stored in the memory to determine a rotational speed and / or rotational speed of the actuator. By forming the difference, a change over time of the average count rate of the counter and thus of the capacity is determined. Such a temporal change of the capacity indicates a change of the rotation angle 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, for example, a heating valve can be read with low power consumption and transmitted, for example, to a receiver.

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

According to a preferred embodiment, the electromechanical unit further comprises an electric motor drive, wherein at least a part of the motor drive and the comparator and the counter are arranged on a circuit board. In addition, in some embodiments, the first and / or second contacting electrode of the rotary sensor may be arranged on the circuit board. This allows a compact arrangement of the components.

Other features and advantages will become apparent from the following description of preferred embodiments. It shows

1a a section of a device,

1b an exploded view of the device according to 1a .

1c the representation of the device according to 1a , b in a view from below,

2a an exploded view of a carrier element with a coupling electrode,

2 B the carrier element and the coupling electrode after 2a in a view from below,

2c an exploded view of a support member with an alternatively designed coupling electrode,

2d the carrier element and the coupling electrode after 2c in a view from below,

3a an exploded view of a section of a device obliquely from below,

3b the exploded view after 3a in a view from above,

4a an exploded view of a support member with a coupling electrode obliquely from above,

4b an exploded view of the carrier element with coupling electrode according to 4a from diagonally below

5 the change in the capacitance of the capacitor as a function of 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 another embodiment.

In the 1a -C and 2a , b is a capacitive rotation sensor. This has a carrier element, which serves as a printed circuit board 10 is formed (s. 1a and 1b ). On the circuit board 10 are contacting electrodes 2 . 11 . 12 arranged. The contacting electrodes 11 and 12 can be conductive together to form a total electrode 1 which are connected by the Kontaktierelektrode 2 is electrically insulated, between the Kontaktierelektroden is in the circuit board 10 an opening 16 provided to an axle 4 take. The axle element 4 runs perpendicular to the circuit board 10 , At the axle 4 is a carrier element 30 arranged, which is designed as a gear. The carrier element 30 points in one of the circuit board 10 adjacent area a larger radius and jumps in one of the circuit board 10 spaced area back to a smaller radius. In both areas is the support element 30 each toothed on its circumference. Further, another gear is 6 provided, which has teeth on its outside. The teeth of the gear 6 engage in the teeth of the support element 30 one. In some embodiments, the gear wheel 6 be coupled directly or indirectly with an electric motor. In this way, the movement of the rotor of the electric motor on the support element 30 transfer.

On the underside of the carrier element 30 there is a coupling electrode 3 (S. 1c . 2a and 2 B ). The coupling electrode 3 is cross-shaped and is at the bottom of the support element 30 centered. Thus, the coupling electrode has 3 in terms of through the axle 4 defined axis of rotation a 4-fold rotational symmetry with four eccentricities.

During a rotation of the carrier element 30 a spatial overlap between the coupling electrode changes 3 and the contacting electrodes 11 . 12 and 2 , Because of the regarding through the axle 4 defined axis not rotationally symmetrical arrangement of the coupling electrode 3 As a result, changes between the interconnected electrodes 11 . 12 and the contacting electrode 2 formed capacity. The course of the capacity as a function of the angle of rotation of the support element 30 is periodically in the angle of rotation of the support element 30 with a period of 90 °. In a preferred embodiment of the invention, the two contacting electrodes 11 and 12 not connected to a total electrode, but contacted individually. In the process, the contacting electrodes become 11 and 12 set to different electrical potentials, so that with a suitable counter electrode on the capacitance change and the direction of rotation can be detected. In another embodiment of the invention, the two contacting electrodes 11 . 12 be set to a common electrical potential, but have different capacities, by their area, shape and / or their axial distance (perpendicular to the PCB level) to the counter electrode 3 be chosen differently. For example, the printed circuit board may have a small step on which one of the two contacting electrodes 11 . 12 is applied. As a result, further embodiments of the invention are described with which a detection of the direction of rotation via a capacitance change is possible.

In the example of 1a to 1c there is a caseback 51 between the circuit board 10 and the carrier element 30 , the analogous to the opening 16 having another opening through which the axle element 4 can be performed. However, it may also be advantageous, the axle in the housing bottom 51 integrate so that no opening in the housing and / or in the circuit board 10 is necessary, resulting in several benefits. On the one hand, the housing can then be better sealed against moisture or dirt and on the other hand, both for the circuit board 10 as well as for the case back 51 smaller wall thicknesses are chosen because the construction is not weakened by openings. This allows the distance between Kontaktierelektroden 2 . 11 . 12 and coupling electrode 3 be reduced and thus an increase in capacity can be achieved. It is also conceivable that the carrier element 30 on the case back 51 rests. The caseback 51 between the on the circuit board 10 and the carrier element 30 To place applied electrodes has the further advantage that by choosing a suitable material, a dielectric with a high dielectric constant ε _r can be used, so that the capacitance of the capacitors formed by the electrodes can be further increased (ε _r > 1), than this with air as a dielectric (ε _r ≈ 1) would be possible.

Another, optional but advantageous embodiment is by attaching a shielding electrode 13 given. This in 1c shown shielding electrode 13 is preferably below the circuit board 51 , one or more of the contacting electrodes 2 . 11 . 12 opposite, attached and can, for example, directly to the circuit board 51 be evaporated. In the example, the shielding electrode 13 formed as a grid structure and provided with openings which are the openings of the circuit board 10 are arranged accordingly. Of course, the shielding electrode in other embodiments may also have a different geometry.

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

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

In the 4a and 4b is a carrier element 30 '' according to a further embodiment, which differs from the carrier elements 30 and 30 ' distinguished by the shape of the electrode applied. The carrier element 30 '' is constructed as a concentric arrangement of two gears with different radii. At the bottom of the gear with a larger radius is an electrode 3 '' , The electrode 3 '' surrounds a central axis of the carrier element 30 '' sickle-shaped. It spans the electrode 3 '' for example, an angle of about 180 ° around the central axis. It may be provided in some embodiments that the electrode 3 '' is used as a coupling electrode to capacitively couple a first and a second contacting electrode with each other. The crescent-shaped coupling electrode 3 '' has the advantage that it causes an asymmetric change in the capacity during rotation via one or more contacting electrodes, whereby the direction of rotation can be determined easily and reliably. Of course, other forms for the coupling electrode are possible in order to achieve an asymmetric capacitance curve. However, it may also be provided in some embodiments that a crescent-shaped electrode, such as those in the 4a and 4b represented electrode 3 '' , is formed as a first or second contact electrode of a capacitor. For this purpose, the potential of the electrode 3 '' be guided electrically to the outside.

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

6 shows a circuit diagram of a device according to an embodiment. The capacitive rotation sensor is shown as capacitor C with variable capacity. As a rotation sensor, for example, in the 1 to 4 illustrated arrangements are used. A first contact electrode of the capacitor C is connected to the input of an inverting Schmitt trigger 110 connected while a second contact electrode of the capacitor C is grounded. The designation of a first and a second contact electrode introduced in this context does not necessarily coincide with the definition as used above in connection with the description of rotary sensors. For example, in each case one of the contacting electrodes 1 . 2 . 1' . 2 '' are grounded and the other contacting electrode of the sensor to be connected to the input of the Schmitt trigger. An exit 111 of the inverting Schmitt trigger is also connected via a resistor R also to the first contact electrode of the capacitor C. Further is the exit 111 the Schmitt trigger 110 with a counting input 121 a counter 120 connected. The counter 120 also has an activation input (enable - EN) 122 which is connected to a signal generator of the device (not shown). The signal generator is at the activation input 122 of the counter 120 a pulsed signal 125 ready. The counter 120 counts the pulses in the at the output 111 the Schmitt trigger 110 provided signal during a pulse of the signal 125 , At the end of a period of the signal 125 sets the counter 120 the count returns to zero.

To illustrate the operation of the device, it is first assumed that the output 111 the Schmitt trigger shows a high level. This is also applied to the first contact 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 the second contacting electrode of the capacitor exceeds a predefined upper threshold value, the inverting Schmitt trigger switches 110 his exit 111 to a low level. This is also applied to the first contact electrode of the capacitor C via the resistor R. The capacitor C is now discharged via the resistor R again. As soon as the charging voltage of the capacitor C drops below a predetermined lower threshold value, the inverting Schmitt trigger switches 110 his exit 111 to a high level and the capacitor C is charged again. As a result of the repeated charging and discharging of the capacitor C, the output of the Schmitt trigger tilts between high and low levels, and this results in the reference number 115 illustrated binary output signal of the Schmitt trigger 110 ,

The period of the output signal 115 depends on the capacitance of the capacitor C, the resistance R and the upper and the lower threshold of the Schmitt trigger 110 from. Of these influencing variables, only the capacitance of the capacitor C is variable. The larger the capacitance of the capacitor C, the larger the time period required for charging or discharging the capacitor C. Thus, the period of the output signal also depends 115 the Schmitt trigger 110 from the capacitance of the capacitor C from. Since the capacitance of the capacitor C in turn depends on a rotation angle of the actuator of the rotary sensor, the frequency of the output 111 the Schmitt trigger 110 output signal 115 a measure of the angle of rotation of the actuator.

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

The counter 120 counts those in the signal 115 at the exit 111 the Schmitt trigger 110 present pulses only during one pulse in the signal 125 at the activation input 122 of the meter 120 , During the rest of a beat of the signal 125 , ie, if there is no pulse, the counter result of the counter remains 120 constant. This counter result shows a mean count rate of the counter 120 during the previous pulse and thus a frequency of the signal 115 at. It may be provided in some embodiments that the device transmits this constant counter result by means of a transmitter (not shown) while the signal 125 shows no pulse. At the end of each bar of the signal 125 , ie at the beginning of each next pulse, the counter result of the counter is set to zero.

7 exemplifies the course of a count of the counter 120 over nine consecutive pulses of the pulsed signal 125 , that is, as a function of the time t, while the rotational angle of the actuator is changed. The pulses are in your output signal 115 the Schmitt trigger 110 each across a pulse width of the pulsed signal generated by the signal generator 125 counted. It can be provided, for example, that the pulsed signal 125 has a frequency of 1 kHz while the frequency of the output signal 115 the Schmitt trigger 110 is in the range of about 1 MHz. The exact value of the frequency of the output signal 115 As described above, it depends on the current capacitance of the capacitor C and thus on the angle of rotation of the actuator. As in 7 shown thus result per pulse of the pulsed signal 125 a different number of pulses of the output signal 115 the Schmitt trigger 110 , Here, the number of pulses of the output signal 115 approximately inversely proportional to the capacitance of the capacitor C. The in 7 shown count results per pulse of the pulsed signal 125 thus provide averages of the count rates at the counter 120 In order to allow an accurate determination of the position of the actuator, it is advantageous that the frequency of the pulsed signal 125 is significantly less than the frequency range in which the output signal 115 the Schmitt trigger 110 emotional. When using an asymmetric coupling electrode, as z. Tie 4a and 4b is shown, there is the advantage that the approximately periodic progression of the mean values of the count rates over the time t within a period has an asymmetry (not shown) over which the direction of rotation can be easily determined.

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

The in the 8a and 8b The device shown is designed as a valve actuator for a heater. The carrier element 30 ''' is part of one of an electric motor 7 driven gear arrangement 8th , The electric motor drives a drive gear 6 '' on, the force on the gear assembly with the support element 30 ''' bin transmits to a driven gear. The output gear is then connected to an eccentric disc, via which the heating valve can be adjusted. For this purpose, the inner ring of a roller 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. Usually, such valves are provided with return springs, against the force of the electric motor must work. In order to reduce the force required when adjusting the valve, it may therefore be advantageous to at least partially compensate for the restoring force of the valve by means of another spring. In the present embodiment, the spring is designed as a torsion spring, one leg of which is mounted on the housing of the Heizungsventilstellers while the other leg presses against the rolling bearing. For more details on the radiator valve control, see also the DE 10 2012 102 615 A1 , whose contents for the execution of the valve actuator and its effect is expressly included in the present disclosure.

Further modifications of the illustrated embodiments are possible. For example, instead of an inverting Schmitt trigger, in some embodiments, another measuring device may be used to determine capacitance. 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. It may be provided in some embodiments that the device has a transmitter for transmitting a count result of the counter. The coupling electrode or one of the contacting electrodes may be coupled to the rotor of a motor or a movable part of a valve.

LIST OF REFERENCE NUMBERS

1, 1 ', 2, 2'

contacting electrode

10, 10 ', 10' ''

circuit board

11, 12,

contacting electrode

13, 13 '

shield

16, 16 '

opening

3, 3 ', 3' '

coupling electrode

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

support element

4, 4 '

axle

5, 5 '

casing

51, 51 '

baseplate

6, 6 '

Pinion

110

comparator

111

output

115

signal

120

counter

121

Counting

122

enable input

125

signal

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102009019172 A1 [0002]
• US 7126495 B2 [0002]
• DE 102012102615 A1 [0072]

Claims (17)

Device comprising: - a capacitive rotation sensor in the form of a capacitor (C), which has a first and a second contacting electrode ( 1 . 2 ; 1' . 2 ' ), between which a capacitance is formed, which varies periodically in dependence on a rotational angle of an actuator of the rotary sensor, - a comparator (C) coupled to the comparator ( 110 ), one between the first and the second contacting electrode ( 1 . 2 ; 1' . 2 ' ) compares the charging voltage dropping across the capacitor (C) with an upper and a lower threshold, and based on a result of the comparison, outputs an output signal ( 115 ) at an exit ( 111 ) of the comparator ( 110 ), - one between the first contact electrode ( 1 . 2 ; 1' . 2 ' ) and the output ( 111 ) of the comparator ( 110 ) coupled resistor (R) and - one to the output ( 111 ) of the comparator ( 110 ) coupled counters ( 120 ). Device according to claim 1, wherein the capacitor (C) further comprises a coupling electrode ( 3 ; 3 '; 3 '' ), which of the first and the second contact electrode ( 1 . 2 ) is electrically isolated and is rotatable relative thereto about an axis, wherein between the first and the second contacting electrode ( 1 . 2 ) formed by turning the coupling electrode ( 3 ; 3 '; 3 '' ) is variable about the axis. Device according to claim 2, wherein the coupling electrode ( 3 ; 3 '; 3 '' ) to the first and second contact electrodes ( 1 . 2 ) each having a distance in the axial direction of at least 1 mm. Apparatus according to claim 2 or 3, wherein the coupling electrode ( 3 ; 3 '; 3 '' ) as an electrically conductive layer on a carrier element ( 30 ; 30 '; 30 ''; 30 ''' ) is arranged. Device according to claim 4, wherein the coupling electrode ( 3 ; 3 '; 3 '' ) by vapor deposition on the carrier element ( 30 ; 30 '; 30 ''; 30 ''' ) is available. Device according to one of claims 2 to 5, wherein the coupling electrode ( 3 ) has an n-fold rotational symmetry with respect to the axis, where n is a positive and integer number. Device according to one of the preceding claims, wherein the first and / or the second contacting electrode ( 1 . 2 ) on a printed circuit board ( 10 ; 10 ' ) are arranged. Apparatus according to claim 7, further comprising the counter ( 120 ) and / or the comparator ( 110 ) are arranged on the circuit board. 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 a constant time electrical potential. Device according to one of the preceding claims, wherein the capacitive rotation sensor more than two contacting electrodes ( 1 . 2 ; 1' . 2 ' ) and wherein the contacting electrodes are at least three different electrical potentials. Device according to one of the preceding claims, wherein the comparator ( 110 ) the output ( 111 ) switches to a lower electrical potential when the charging voltage of the capacitor (C) exceeds the upper threshold. Apparatus according to any one of the preceding claims, further comprising a signal generator for generating a pulsed signal ( 125 ), which with the counter ( 120 ), and wherein the counter ( 120 ) Pulse of the output signal ( 115 ) of the comparator ( 110 ) each during a pulse of the pulsed signal ( 125 ) counts. Device according to one of the preceding claims, further comprising a counter to the counter ( 120 ) coupled interface and / or one to the counter ( 120 ) coupled transmitter for transmitting a count result or a count rate of the counter ( 120 ) having. Valve arrangement, in particular with a heating valve, which has the device according to one of the preceding claims for determining a valve position. An electromechanical unit including a motor and the apparatus of any one of claims 1 to 15, wherein a rotor of the motor is coupled to the actuator of the rotation sensor.

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