DE102008031744B4 - Sensor device for determining a rotational frequency - Google Patents

Abstract

Sensor device for determining the rotational frequency of a rotating body, with
- A first arranged on the rotary body electrode means (21);
A second electrode device (10, 11) arranged on the rotary body, the second electrode device (10, 11) being connected to a client circuit (12) which comprises a modulator; and
- An evaluation circuit (40) which is connected to the first electrode means (21) and designed for generating the electric field, for detecting field electrical interactions, which serve as a basis for determining the rotational frequency of the rotating body, with at least one of the two electrode means, wherein the first electrode means (21) is operable as a transmitting electrode, for coupling the electric field in at least the region of the rotational body in which the second electrode means (10, 11) is arranged;
wherein the modulator is configured to modulate the coupled alternating electric field, wherein an evaluation unit of the evaluation circuit (40), the modulated electric field can be supplied by the first electrode means (21) additionally operable as a receiving electrode ...

Description

The The invention relates to a sensor device for determining a Rotational frequency of a rotating body. In particular, the invention is directed to a sensor device for determining the rotational frequency of a drum in a tumble dryer or a washing machine. The determination of the rotational frequency of the drum takes place here due to the determination of the rotational frequency of the support roller with the sensor device according to the invention.

In many areas must have the rotation and / or the rotational frequency of rotation bodies recorded or monitored become. For example, the rotation of the drum must be detected in a tumble dryer be in order in the event of a belt tear of the belt, which the Drum drives, an ignition dry laundry to prevent.

Out The prior art is known by usually consuming and error-prone direct or indirect measurements on the one rotating body driving Motor, the rotation or the rotational frequency of the rotating body, about the drum in a tumble dryer capture. In this case, for example, the load applied to the engine measured, which must have a certain value, thus a rotation the drum (even when empty) is detected. Moves the the drum or belt driving motor without load, d. H. in the Idle, this can be interpreted as an indication that the drum in the tumble dryer is no longer driven.

From the DE 10 2004 059 165 A1 For example, a method and apparatus for determining the direction of rotation of a wheel in a vehicle is known. For this purpose, two offset in the direction of rotation capacitors are provided on the wheel, being closed from the rotation-related change in the capacitance of the capacitors on the direction of rotation of the wheel. The change in the capacitor currents associated with the capacitance change is measured by an evaluation circuit which is galvanically coupled to the capacitors.

Measurement results can for example by means of a radio link to a control unit transferred inside the vehicle become.

From the DE 44 03 646 A1 is a rotational speed sensor with a vibration generating transmitting device and two receiving device, which detect the rotational movement of a solid about its axis of rotation known. The rotational speed sensor operates on the Coriolis principle, wherein the propagation of an acoustic wave generated at the surface of the solid body is evaluated for determining the rotational speed.

Of the Invention has for its object to provide solutions by which makes it possible is, the rotation and / or the rotational frequency of a body of revolution, about a drum of a tumble dryer or to determine a washing machine in a simple way one on the rotary body arranged part of the sensor device without its own power supply can be operated and wherein an evaluation circuit outside of the rotational body can be arranged.

These The object is solved by the features of independent claim 1. Further advantageous embodiments will be apparent from the dependent claims.

• – einer ersten am Rotationskörper angeordneten Elektrodeneinrichtung;
• – einer zweiten am Rotationskörper angeordneten Elektrodeneinrichtung, wobei die zweite Elektrodeneinrichtung an eine Clientschaltung angebunden ist, welche einen Modulator umfasst; und
• – einer Auswerteschaltung, welche mit der ersten Elektrodeneinrichtung verbunden ist und zur Erzeugung des elektrischen Feldes ausgestaltet ist, zur Erfassung feldelektrischer Wechselwirkungen, welche als Grundlage für die Ermittlung der Drehfrequenz des Rotationskörpers dienen, mit wenigstens einer der beiden Elektrodeneinrichtungen, wobei die erste Elektrodeneinrichtung als Sendeelektrode betreibbar ist, und zwar zur Einkoppelung des elektrischen Feldes in wenigstens dem Bereich des Rotationskörpers, in dem die zweite Elektrodeneinrichtung angeordnet ist;

wobei der Modulator ausgestaltet ist, das eingekoppelte elektrische Wechselfeld zu modulieren, wobei einer Auswerteeinheit der Auswerteschaltung das modulierte elektrische Feld zuführbar ist, indem die erste Elektrodeneinrichtung zusätzlich. als Empfangselektrode betreibbar ist, und wobei die Clientschaltung mit dem von der ersten Elektrodeneinrichtung eingekoppelten elektrischen Feld mit Energie versorgt wird.Accordingly, a sensor device is provided for determining the rotational frequency of a rotating body

• - A first arranged on the rotary body electrode device;
• A second electrode means arranged on the rotation body, wherein the second electrode means is connected to a client circuit which comprises a modulator; and
• - An evaluation circuit, which is connected to the first electrode means and configured to generate the electric field, for detecting field electrical interactions, which serve as the basis for determining the rotational frequency of the rotating body, with at least one of the two electrode means, wherein the first electrode means as a transmitting electrode is operable, and indeed for coupling the electric field in at least the region of the rotary body, in which the second electrode means is arranged;

wherein the modulator is configured to modulate the coupled alternating electric field, wherein an evaluation unit of the evaluation circuit, the modulated electric field can be supplied by the first electrode means in addition. is operable as a receiving electrode, and wherein the client circuit is supplied with the coupled from the first electrode means electric field with energy.

In a preferred embodiment For example, the second electrode device may comprise an electrode which arranged asymmetrically relative to the axis of rotation of the body of revolution is.

The electric field, which is generated and emitted by the first electrode device, can be frequency-modulated with the rotational frequency of the rotational body, wherein from the frequency-modulated electric field, the rotational frequency of the Ro is derivable body.

In a further preferred embodiment the sensor device comprises the second electrode device a first electrode and a second electrode, wherein the first Electrode arranged in the region of the first electrode device and wherein the second electrode is preferably in the outer region of the rotational body is arranged.

The second electrode device or the first electrode and the second Electrode can be connected to a client circuit, which with that of the first electrode device coupled with electric field Energy is supplied. The second electrode device can thereby Capacitive to the client circuit be connected. As such, the client circuit can generate signals that for example, due to a change the capacitive coupling of the second electrode are changed to ground can. A signal feedback of the changes detected by the client circuit of a capacitive Coupling to the ground for the evaluation circuit can via the first electrode device respectively. The signal feedback to The first electrode device can in particular by load modulation or impedance modulation in the region of the first electrode device respectively.

The electric field can be amplitude modulated with the rotational frequency of the rotating body be, where from the amplitude modulated electric field, the Rotational frequency of the rotating body is derivable.

Several on the rotating body (or to several rotation bodies) arranged second electrode means are preferably designed to be distinguishable from the evaluation unit are. This can be done, for example, by means of a Fourier transformation, preferably in the evaluation unit.

Especially Advantageously, it is the first electrode device with a stationary, metallic designed to connect the rotational axis of the body of revolution. The rotation axis acts as an electrode.

Of the body of revolution can be a drum of a tumble dryer or a washing machine. In addition, the rotation body can also be at least a support roller for a drum of a tumble dryer or a washing machine, wherein the rotation or the rotational frequency the drum of the rotation or the rotational frequency of the Auflagerolle is derivable.

at a tumble dryer or a washing machine with a drum, with the drum on is mounted at least one rotatably mounted support roller, and a sensor device according to the invention to determine the rotational frequency of the drum, can be determined by the capacitive Coupling of arranged on the support roller second electrode means with the drum the rotational frequency of the drum can be determined, whereby the first electrode device with the stationary, metallic designed Rotary axis of Auflagerolle is connectable.

• a) durch eine erste Elektrodeneinrichtung ein elektrisches Feld erzeugt wird,
• b) das elektrische Feld in eine zweite Elektrodeneinrichtung eingekoppelt wird, wobei das eingekoppelte elektrische Feld von einem Modulator einer Clientschaltung, welche an die zweite Elektrodeneinrichtung angebunden ist, moduliert wird und wobei die Clientschaltung mit dem eingekoppelten elektrischen Feld mit Energie versorgt wird, und
• c) die Drehfrequenz des Rotationskörpers von einer Auswerteeinheit, welche mit der ersten Elektrodeneinrichtung gekoppelt ist, aus dem modulierten elektrischen Feld abgeleitet wird.

Provided by the invention is also a method for determining the rotational frequency of a rotational body, wherein

• a) an electric field is generated by a first electrode device,
• b) the electric field is coupled into a second electrode device, wherein the coupled electric field is modulated by a modulator of a client circuit which is connected to the second electrode device, and wherein the client circuit is supplied with the injected electric field, and
• c) the rotational frequency of the rotational body is derived from an evaluation unit, which is coupled to the first electrode device, from the modulated electric field.

Further Advantages and advantageous embodiments of the invention are the Description, the drawings and claims removed.

embodiments the invention are shown schematically simplified in the drawing and will be explained in more detail in the following description.

It shows

1 a first embodiment of a sensor device according to the invention; and

2 a second embodiment of the sensor device according to the invention.

following becomes the inventive concept a sensor device for determining the rotational frequency of a rotating body on Example of a tumble dryer explained in more detail. The inventive concept let yourself, with adaptations to each requirement, to each Transfer type of rotation body.

A drum of a tumble dryer is stored on two or four support rollers and driven by a motor via a drive belt. According to the inventive concept, which will be described below, the rotation of the support rollers can be detected to a unique To provide information about the rotation of the drum or about the rotational frequency of the drum.

A first embodiment of the sensor device according to the invention is in 1 shown.

1 shows a drum of a tumble dryer, which is mounted on two rotatably mounted support rollers. Also is in 1 an enlarged view of a Auflagerolle shown, in which in particular the arrangement of the electrodes 10 . 11 will be apparent on the Auflagerolle.

On both support rollers, a so-called. ZPS client is arranged, which essentially consists of the electrodes 10 . 11 as well as a client circuit 12 consists. The electrodes 10 . 11 are connected to the client circuit. In 1 are the electrodes 10 . 11 shown galvanically connected. The electrodes 10 . 11 but can also be capacitively connected to the client circuit, which allows a particularly flexible use of the sensor device according to the invention.

A first electrode 11 is doing with the metallic plain bearing bushing 20 connected to the support roller. The second electrode 10 is arranged in the form of a ring segment or in the form of a thin crescent in the outer region or at the edge of the support roller. The stationary and also metallic axis of rotation 21 the support roller is connected to a server electrode, which is part of an evaluation circuit (a so-called. ZPS server, see below).

As the drum rotates, the support rollers rotate due to the bearing of the drum on the support rollers. As the support rollers rotate, the outer electrode approaches 10 cyclically with the rotational frequency of the Auflagerolle the drum or moves away from the drum again. The rotational frequency of the drum is proportional to the rotational frequency of the support rollers, so that from the rotational frequency of the support rollers, the rotational frequency of the drum is derivable.

At the approach of the electrode 10 to the drum increases the capacitive coupling of the electrode 10 to the mass. Conversely, the capacitive coupling of the electrode decreases 10 to the ground when the electrode 10 removed from the drum again.

Of the ZPS server essentially comprises an oscillator in its basic structure, which generates an AC voltage, then from the generated electric field, and a server electrode, via which the generated electric field is emitted or radiated. The oscillator For example, a limiter, for example a resistor, can be connected downstream be, to possibly flowing currents no over outgrow a certain amount allow. At this limiter can be used by the client circuits generated modulation are fed to an evaluation unit.

The server electrode is connected to the metallic rotation axis of the support roller so that the rotation axis acts as the server electrode of the ZPS server. The electric field radiated from the server electrode and from the rotation axis of the support roller, respectively, becomes the electrode 11 of the ZPS client, which also provides power to the client circuit 12 allows.

The client circuit 12 comprises a modulator with an oscillator which starts to oscillate as soon as a sufficiently large electric field from the server electrode into the electrode 11 is coupled. In addition, the client circuit includes voltage converters for converting over the electrode 11 recorded alternating field in a DC voltage. With this voltage, the modulator is operated with the oscillator. According to the input voltage, the modulator has a certain level with which the (coupled) AC voltage can be modulated. This level changes, for example, when the capacitive environment of the client circuit changes. The level change thus results in a change in the level of the AC voltage, which can be evaluated by the server circuit.

When the outer electrode approaches 10 As the drum drifts, the capacitive coupling to ground increases, causing the signal provided by the ZPS server to change in amplitude. The electric field is thus amplitude-modulated with the rotational frequency of the support rollers; The amplitude-modulated signal can be detected by the ZPS server and supplied by this to an evaluation unit. The evaluation unit can determine a drum movement or the rotational frequency of the drum on the basis of the amplitude-modulated signal.

The Amplitude modulation of the electric field is a clear one Prove for, that the drum is in motion. As the rotational frequency of the support roller proportional is the rotational frequency of the drum, can from the rotational frequency of the Support roller, for example, by analyzing the outer envelope of the amplitude modulated signal determines the rotational frequency of the drum become.

By supplying the ZPS client (essentially consisting of the electrodes 10 . 11 and the client circuit 12 ) with energy through the electric field provided by the ZPS server can access its own power supply be dispensed with for the ZPS client, which allows a particularly compact design of the ZPS client.

Become several support rollers for determining the rotational frequency of the drum used, d. H. in each case a ZPS client at several storage rolls is arranged and that the respective metallic axes of rotation with can be connected to the ZPS server or its server electrode made a redundant determination of the rotational frequency of the drum which is necessary, especially for security reasons can be.

The individual ZPS clients are designed in such a way that the evaluation unit the ZPS server receives the signal amplitude modulated by the ZPS clients can be separated and assigned according to the individual ZPS clients. Therefor can different measures are provided on the side of the ZPS clients become.

For example can the individual client circuits a free-running oscillator provide which with a different oscillator frequency be operated, so that at the server circuit (with several ZPS clients) a frequency mix of different frequencies with different Amplitudes applied, which z. B. by means of a Fourier transform can be separated accordingly. Thus, the rotational frequency of several Auflagerollen be determined, which in addition to the redundant design For safety reasons too an exam the functionality the individual support rollers allowed, as the individual support rollers with approximate should turn the same rotation frequency.

Instead of a freewheeling oscillator may also provide a frequency divider which is the frequency of the oscillator signal of the server circuit Splits. Preferably, the division ratio is in the individual ZPS clients different, so the individual ZPS clients each with different Frequency work and the alternating field of the server circuit with different Frequency amplitude modulation.

alternative can also be provided a comparator, which one on the carrier signal the server circuit modulated identification number with a compares the identification number assigned to the ZPS client. At agreement can the ZPS client activates the modulator. After activation takes place then the modulation of the carrier signal. The server circuit can thus target one of several ZPS clients Interrogate.

A Another alternative is to provide a timer. Thereby can be achieved that with appropriate adjustment of the timers Only one ZPS client is active at a time.

With appropriate arrangement of the electrodes of the ZPS client and the server electrode can also be achieved that the ZPS client with the rotational frequency of the Auflagerolle on or off (usually in the range of a few Hz), since the distance of the electrode 11 to the server electrode of the server circuit with the rotational frequency of the Auflagerolle changes. The cyclic switching on and off of the client circuit leads to a cyclically existing load modulation, which can be recognized by the evaluation unit of the server circuit in the frequency spectrum. In turn, the rotational frequency of the support roller can be derived from this.

Of course it is also possible, besides the two in 1 shown support rollers to provide additional support rollers with a corresponding sensor device.

2 shows a further embodiment of the sensor device according to the invention. Instead of in 1 ZPS clients shown here is an electrode at the Auflagerolle 30 arranged, which preferably with the plain bearing bush 20 connected is. It is particularly advantageous, the electrode 30 to be arranged asymmetrically relative to the axis of rotation on the support roller. As in the embodiment according to 1 can also be configured in this embodiment, the electrode ring-segment-shaped or crescent-shaped. The electrode may for example consist of a conductive lacquer layer.

The stationary metallic axis of rotation 21 is as in the embodiment according to 1 connected to the ZPS server or its server electrode.

Again, the rotation of the drum causes a rotation of the support rollers. As the support roller rotates, the electrode approaches 30 the drum, which has an increase in the capacitive coupling of the server electrode or connected to the server electrode metallic axis of rotation to the mass result. In the opposite case, so if the electrode 30 due to the rotation away from the drum again, reduces the capacitive coupling of the server electrode or coupled to the server electrode axis of rotation to ground. The cyclic, with the rotational frequency of Auflagerolle, approach or removal of the electrode 30 to or from the drum causes the oscillator frequency of the ZPS server to change. The electric field or the oscillator frequency of the ZPS server is thus frequency-modulated with the rotational frequency of the support roller. This frequency change of the oscillator is detected by the evaluation unit of the ZPS server and can thus with regard to the determination of the rotational frequency of the Auflagerolle, or derived therefrom, the drum can be used. The structure of the ZPS server essentially corresponds to the structure as it relates to 1 has been described. Here, too, the rotational frequency of the drum can be derived from the frequency-modulated signal, since the rotational frequency of the drum is proportional to the rotational frequency of the support roller.

With the in 2 In particular, measurements with very high rotational frequencies (in the kHz range) can also be carried out.

When using two or more support rollers for rotation frequency detection, the electrodes should be 30 be configured, or arranged on the support roller, that there is no antiphase rotation with respect to the arranged on the support rollers electrodes 30 comes, or that the capacitance changes at the electrodes 30 do not compensate each other, which would result in minimizing the frequency modulation of the oscillator frequency.

The electrodes 30 should therefore be designed such that the capacity changes to the individual support rollers remain asymmetrical to each other, so that an evaluation carried out by the ZPS server of the frequency-modulated signal is easier.

An advantageous embodiment of the electrode 30 is in 2 shown. The electrode 30 is designed narrow, which has the consequence that the capacity curves with respect. The two support rollers are particularly asymmetrical to each other.

Also in this embodiment, instead of the two in 2 shown bearing rollers further Auflagerollen be equipped with the sensor device according to the invention, which is also here to pay attention to the symmetry of the capacity curves. In both sensor devices shown in the two embodiments, two or more support rollers provided with a sensor device can each be connected to a ZPS sensor.

The inventive sensor device has the special advantage of having minimal interference with one already existing construction of a tumble dryer feasible is.

Furthermore can the sensor device according to the invention stored on any type of rotatably mounted support rollers Rotation body for Determining the rotational frequency of the rotating body can be used.

Provided in the two embodiments shown drum is not coupled to ground, for example also the cyclical approach the electrode of the support roller to the (grounded) housing of Washing machine or tumble dryer be recorded.

Especially can the sensor device according to the invention also used in a ZPS network become. A ZPS network essentially comprises a ZPS server of the above type, where a number of ZPS clients (such as about the sensor device according to the invention) can be connected. The ZPS server is designed to handle the different ZPS clients or the separate or distinguish signals provided by the ZPS clients can.

Claims (13)

Sensor device for determining the rotational frequency of a rotary body, comprising - a first electrode device arranged on the rotary body ( 21 ); A second electrode device arranged on the rotary body ( 10 . 11 ), wherein the second electrode device ( 10 . 11 ) to a client circuit ( 12 ), which comprises a modulator; and - an evaluation circuit ( 40 ) connected to the first electrode device ( 21 ) and is designed to generate the electric field, for detecting field-electrical interactions, which serve as the basis for determining the rotational frequency of the rotary body, with at least one of the two electrode devices, wherein the first electrode device ( 21 ) is operable as a transmitting electrode, specifically for coupling in the electric field in at least the region of the rotational body in which the second electrode device ( 10 . 11 ) is arranged; wherein the modulator is configured to modulate the coupled alternating electric field, wherein an evaluation unit of the evaluation circuit ( 40 ) the modulated electric field can be supplied by the first electrode device ( 21 ) is additionally operable as a receiving electrode, and wherein the client circuit ( 12 ) with that of the first electrode device ( 21 ) coupled to the electric field is energized. Sensor device according to claim 1, wherein the second electrode device ( 10 . 11 ) comprises an electrode which is arranged asymmetrically relative to the axis of rotation of the body of revolution. Sensor device according to claim 1 or 2, wherein the electric field with the rotational frequency of the rotational body is frequency modulated and wherein from the frequency-modulated electric field, the Rotation frequency of the rotating body is derivable. Sensor device according to claim 1, wherein the second electrode device ( 10 . 11 ) comprises a first electrode and a second electrode, wherein the first electrode in the region of the first electrode device ( 21 ) and wherein the second electrode is arranged in the outer region of the rotary body. Sensor device according to claim 4, wherein the second electrode device ( 10 . 11 ) capacitively to the client circuit ( 12 ) is attached. Sensor device according to claim 4 or 5, wherein the electric field with the rotational frequency of the rotational body amplitude modulated is and where from the amplitude modulated electric field, the Rotational frequency of the rotating body is derivable. Sensor device according to one of the preceding claims, wherein several on the rotation body arranged second electrode means of the evaluation unit are distinguishable. Sensor device according to one of the preceding claims, wherein the first electrode device ( 21 ) is coupled with a metallic pivot axis. Sensor device according to one of the preceding claims, wherein the rotation body a drum of a tumble dryer or a washing machine. Sensor device according to one of claims 1 to 8, wherein the rotational body at least one support roller for a drum of a tumble dryer or a washing machine, wherein from the rotational frequency of the Auflagerolle the rotational frequency of the drum is derivable. Dryer with a drum, wherein the drum is mounted on at least one rotatably mounted Auflagerolle, with a sensor device according to one of the preceding claims for determining the rotational frequency of the drum, wherein based on the capacitive coupling of the arranged on the support roller second electrode means ( 10 . 11 ) with the drum, the rotational frequency of the drum can be determined, and wherein the first electrode means ( 21 ) is coupled to the metallically configured axis of rotation of the support roller. Washing machine with a drum, wherein the drum is mounted on at least one rotatably mounted support roller, with a sensor device according to one of the preceding claims for determining the rotational frequency of the drum, wherein based on the capacitive coupling of the arranged on the support roller second electrode means ( 10 . 11 ) with the drum, the rotational frequency of the drum can be determined, and wherein the first electrode means ( 21 ) is coupled to the metallically configured axis of rotation of the support roller. Method for determining the rotational frequency of a rotational body, wherein a) by a first electrode device ( 21 ) an electric field is generated, b) the electric field into a second electrode device ( 10 . 11 ), the coupled-in electric field being from a modulator of a client circuit ( 12 ), which are connected to the second electrode device ( 10 . 11 ) is modulated, and wherein the client circuit ( 12 ) is supplied with the coupled-in electric field with energy, and c) the rotational frequency of the rotational body of an evaluation unit, which with the first electrode means ( 21 ) is derived from the modulated electric field.

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