DE102012011417A1 - Flow meter for water tap in wash basin, has electronic circuit with output device that is connected to piezoelectric film, where value for flow rate depending on electrical current generated by film is specified by output device - Google Patents

Abstract

The flow meter has a housing (6) comprising an inner lateral surface, where liquid i.e. water, flows through the housing. The housing has a ring-shaped piezoelectric film i.e. polyvinylidene difluoride-film (F), for generating electrical current, where the film is arranged on the inner lateral surface. An electronic circuit is provided with an output device that is electrically connected to the piezoelectric film, where a value for flow rate depending on the electrical current generated by the piezoelectric film is specified by the output device. An independent claim is also included for a method for measuring water amount with a flow meter.

Description

The invention relates to a flow meter according to the preamble of claim 1.

The water consumption is usually detected by a flow meter. The flow meter can be centralized for several residential units, z. B. be housed in the basement of a building. The costs of water consumption are then distributed over certain keys. In addition, a recording of the amount of water consumed per unit is known in modern residential buildings. If the water consumption per dwelling unit or even per tap point is to be recorded in an old building, a considerable outlay is associated with the installation of conventional flowmeters in the dwellings or even in individual rooms with removal points.

From the DE 33 28 782 A1 a sanitary fitting with a sensor for a physical parameter is known, which is designed screwed to an outlet opening of the valve. In the housing electronic components and a button battery are housed, wherein a display is provided for displaying a detected by the sensor water temperature.

The invention has for its object to provide a flow meter with which the individual detection of water consumption at all taps is possible with little effort, with the flow meter should be characterized by a compact design and low maintenance.

This object is achieved by a device having the features specified in the characterizing part of claim 1 in conjunction with its preamble features.

The flowmeter according to the invention is not only the consumption of a liquid, z. As water, but can also be used to determine the flow rates of gases. In this respect, the invention extends to both liquids and gases, however, the description of the invention will be explained below with reference to a flow meter for water.

The invention is based on the finding that with a PVDF film which is annular in the region of the outlet of a liquid or gas flowed through the housing, in particular a valve, an electric power is generated in an amount which in a known manner approximately in the 3. Potency of the flow rate, z. B. the liquid is dependent. From the flow rate and the cross section of the housing, the flow rate per unit time can then be determined.

The invention is also based on the idea of making it possible to measure the amount of water at all tapping points without requiring major modifications.

For the generation of electrical energy, it is sufficient if the PVDF film is mechanically deformed by the liquid or gas flowing through the fitting due to the pipe friction and the associated vortex formation. The degree of electrical power generated in this case is dependent on the flow rate and thus the flow rate in approximately the 3rd power.

In order to gain or generate the energy from the flow, basically the vortex principle is used in combination with piezoelectric materials.

If the pipe friction is not sufficient as a "disruptive body", so of course it is possible, for. B. in the area of the pipe wall in the vicinity of the annular PVDF film, to provide artificial obstacles that encourage vortex formation.

By the invention can be dispensed with a battery, which has two major disadvantages. On the one hand, it is relatively large, so that very small dimensions of a flow meter are not possible, and on the other hand, the battery must be replaced after a certain time, which requires a waterproof battery compartment, or even the entire sensor must be replaced.

The flow meter according to the invention is a simple retrofitting, z. B. in the aerator of a faucet or installation in a supply line, possible. The flowmeter can also be in a supply line, for. B. to a shower head can be realized. The invention also allows a small design, so that the sensor is barely recognizable.

The flow meter may be arranged at an outlet opening of a sanitary fitting. As a result, a flow meter can be mounted at each tap without a cable disconnection.

It is possible that additional external energy is provided by a high-frequency circuit comprising a high-frequency receiving unit with an antenna, and converts an external transmission signal according to the RFID principle into electrical energy for supplying the electronic circuit. If the generated energy in the sensor is not sufficient to actively generate a sufficiently strong high-frequency signal, a passive technology known from RFID technology can be used Procedures are applied. A stationary transmitter continuously generates a high frequency signal of constant frequency. This signal is received by a stationary receiver. If the transmission characteristics of the room do not change, the strength of the received signal is constant. This condition can be filtered out by a bandpass filter. The sensor is a tuned to the frequency antenna whose impedance z. B. via a transistor or a capacitance diode of the voltage which is generated by the piezoelectric element so the PVDF film is changed depending on the flow. This change only takes place when water flows through the sensor.

This change in antenna impedance causes the signal strength arriving at the receiver to vary (minimally). These variations in signal strength can be demodulated by a suitable filter, the resulting signal corresponding to the vortex signal, as if there were no radio channel. Again, an existing electronics can be used.

A cable-bound signal transmission via existing copper pipes is also conceivable.

It can be assumed that the z. B. energy generated by the PVDF film is sufficient to produce a radio signal that can still reliably detect a receiver. This makes possible a simple system consisting of a unit for generating energy, a threshold detector and a high-frequency circuit including an antenna. The PVDF film used produces a charge dependent on the flow rate, as described above. The dependence of the charge on the flow velocity can be approximated by a polynomial. This charge can be stored in a capacitor via a low forward voltage diode. The more water has flowed through the sensor, the higher the voltage applied to the capacitor. The use of a ten or avalanche diode is advantageous. As soon as the voltage across the capacitor exceeds a threshold value, an avalanche-like breakthrough occurs (avalanche effect) in the downstream decade or avalanche diode. This is suddenly low impedance, the charge on the capacitor can flow through a coil of the high-frequency circuit. This will cause it to vibrate. The values of the LC combination determine the frequency of these oscillations, which are then transmitted by the antenna. Since only a limited amount of energy has been transferred into the resonant circuit, only a short pulse is generated. This process is repeated periodically so that a flow rate dependent number of high frequency pulses per unit of time is generated.

These pulses can then be received by another antenna in a stationary unit and demodulated and filtered via a simple circuit. The resulting signal consists of individual square pulses, which can be evaluated by the known vortex electronics without any further effort. The vortex electronics may include or control a display unit.

With a stationary unit and multiple sensors can be detected when each sensor is assigned its own carrier frequency for the radio signal.

In order to be able to attach the flow meter to a faucet particularly easily, it is possible for the flow meter to be arranged in a housing which can be screwed to the outlet opening of the sanitary fitting in a thread and through which water flows.

It is also possible that the output unit for outputting the measured value comprises a measuring signal which is modulated onto a carrier frequency, wherein the measuring signal is demodulated by a receiver. The measurement signal, which is a frequency dependent on the flow, may be a repetitive high frequency signal.

Further advantageous embodiments of the invention are described in the subclaims.

In an advantageous embodiment of the drive according to the invention it is provided that the PVDF film is folded several times. This makes it possible to gain greater energy, so that an evaluation is less sensitive to external disturbances.

In a further advantageous embodiment of the invention, the electrical energy generated by the PVDF film is stored in a memory, wherein by the output device, a value for the flow rate is indicated, which is dependent on the value of the stored electrical energy. The stored energy makes it possible to dispense with an additional energy source, for example a battery.

For the decentralized detection of water consumption, it is advantageous if the housing is part of a sanitary fitting. Retrofitting such water meters is easy and inexpensive.

A particularly preferred embodiment of the invention is characterized in that a disruptive body is arranged in the housing in the region of the PVDF film. Increased vortex formation improves the sensor properties.

The invention will be explained in more detail by way of example with reference to the drawings.

Show it:

1 a perspective view of a faucet with a sensor according to the invention,

2 a schematic representation of the faucet,

3 a perspective view of the sensor with a cut-out segment,

4 a schematic representation of the sensor seen from above,

5 a schematic representation of a first embodiment of the sensor from the side or seen

6 a schematic representation of a second embodiment of the sensor from the side or seen

7 a circuit diagram of a circuit with transmitter and receiver,

8th transmitted output signals at different amounts of water or a charging voltage to a storage capacitor and generated radio signals, and

9 a circuit diagram of a circuit according to the RFID principle.

In the figures, like parts are given the same reference numerals.

1 shows a faucet or a sanitary fitting 1 for z. B. a sink. Mounted on it is a flow sensor 2 for measuring water consumption, with the flow sensor 2 a PVDF film F comprises. Together with a receiver 3 ' or a receiver unit with an evaluation 4 he forms a flow meter 5 , The flow sensor 2 or a sensor circuit 2 ' is in a ring or tubular housing 6 embedded in the 3 is shown, and at the on the in 2 marked outlet opening 7 the fitting 1 an external thread 8th is screwed. 3 shows a part of a flow meter. The sensor 2 is also arranged in a ring.

The sensor made by the PVDF film F (polyvinylidene fluoride) 2 you make use of the piezoelectricity of different materials. This consists in the charge separation of certain crystals or partially crystalline materials by mechanical deformation of a crystal lattice.

Polyvinylidene fluoride (C2H2F2) is a semi-crystalline polymer that undergoes piezoelectric properties through a poling process. This material is very flexible material and can be produced as a thin film. The PVDF material used consists for example of about 50% crystalline, partly polar, lamellae. The polarization process can take place as follows:
A process step involves stretching the film and causing the lamellae and thus the dipole moments to be perpendicular to the film plane and contributes to the phase transformation from non-polar to polar phases within the lamellae. Then, in a further process step, the film on z. B. 80-130 ° C heated and applied an electric field. This remains on until the film has cooled. Here, the individual polar lamellae align themselves along the field, ie perpendicular to the plane. After cooling, the film has the desired piezoelectric properties.

It has been found that the PVDF film F, especially when folded several times, provides a sufficient amount of electrical energy, the power generation being based on the following principles:
The pipe wall of in 3 shown housing 6 has a certain roughness. Due to the roughness (Reynolds number) on the pipe wall arise in the region of the pipe wall when flowing through a fluid or gas vortex. These vortices provide a mechanical deformation of the film F, which leads to the generation of electrical energy due to the piezoelectric effect. The larger the flow rate, the more violent the vortex formation. That is, the frequency of the vortices depends on the flow velocity. This means that the generated electrical energy in a known manner is dependent on the flow rate, wherein, taking into account the cross section and the flow velocity, the flow rate per unit time can be determined. It is conceivable that the currently generated electrical energy is displayed converted as a value for the flow rate, which would correspond to a normal flow meter. The electrical energy could be stored, with the amount of stored in a memory, eg. In a capacitor C1 ( 7 ), stored electrical energy represents a measure of the flow rate in a given period of time through the housing 6 has flowed.

The with the sensor 2 interconnected electronic circuit 2 ' ( 7 ) as well as the actual sensor 2 ( 3 ) are themselves on a flexible board 10 arranged. The sensor 2 is ring-shaped arranged. The electronic circuit 2 ' has an output unit 11 to output a reading for water consumption. The measured value here is a frequency or a frequency signal A or B which is in 8th is shown by way of example. 8th shows sawtooth pulses S1, S2 and high-frequency oscillations HF1, HF2 of a transmitting unit 12 the circuit 2 ' ,

The required for the supply of the electronic circuit current I is through the PVDF film F (sensor 2 ) as a piezo element 13 generated.

The power supply virtually comprises an energy recovery unit (piezoelectric element 13 ), which is the external energy, namely the kinetic energy of the water, in the electrical energy used to power the electronic circuit 2 ' transforms.

The external energy is a vortex-derived energy of the water flow of the sanitary fitting 1 ,

4 shows a sensor 2 , which is provided with the annular film F arranged. As 5 is illustrated by an additional obstruction body 14a and a sensor element formed by the film F. 15 as a result of the vortex 16 generates an electrical voltage.

5 shows the sensor 2 with the center in the channel arranged Störkörper 14a and the sensor element 15 through the piezoelectric foils F at the edge or on the inner wall of the tubular housing 6 ( 3 ) is formed.

6 shows a preferred variant in which a bluff body 14b is executed on the edge or as an inwardly projecting survey. This has an approximately triangular shape in cross section. The sensor element 15 is by a piezoelectric film on the edge or on the inner wall of the tubular housing 6 ( 3 ), wherein the film F may also be folded to increase the yield.

These vortex generators ( 4 to 6 ) are z. B. arranged in an aerator.

The electronic circuit 2 ' ( 7 ) of the sensor part is divided into three sections or circles, namely in a circle K1 for energy, a circle K2 for the threshold detection and a high-frequency circuit K3 for radio transmission. The circle K1 for energy production comprises the piezoelectric element 13 , a diode D1 and a capacitor C1. The capacitor is charged quickly at high flow A, which means a steep rise in voltage S1. At low flow B, the capacitor is charged slowly, which is illustrated by the voltage increase S2.

Due to the resonance of the circle K3 is a high-frequency signal z. B. HF1 or ZB HF3 generated by the receiver 3 ' Will be received.

The second circle 2 includes a Zener diode ZD and discharges the capacitor C1. The charge accumulated in the capacitor C1 then flows into the high frequency circuit K3, which includes a tuning capacitor C2 and an RF transformer T1 with transmitting antenna 17 having.

Circles K1 to K3 form a quasi-output unit. The with the sensor 2 (Element 13 ) interconnected electronic circuit has the capacitor C1, the sensor 2 is charged depending on a water flow rate, wherein after reaching the predetermined threshold value of the capacitor voltage, the capacitor C1 is discharged through the Zener diode ZD, so that a dependent of the water flow rate frequency signal (S1, S2 or HF1, HF2) is generated.

In the 7 shown circuit 2 ' is a radio transmitter that sends the frequency signal to the receiver 3 ' sends. The radio signal is transmitted by a vortex electronics (evaluation electronics 4 ) to determine the water flow rate.

The recipient 3 ' ( 3 ) is spatially from the valve 1 away (stationary unit) and includes a receiving antenna 18 , a transformer T2, a diode D3 and an analogue filter F.

That of the sensor 2 The measurement signal generated with a first measurement signal frequency is modulated by the carrier frequency generated by the resonant circuit (capacitance C2 and inductance of the transformer). In the receiver 2 ' this signal is demodulated by the filter again.

For outputting a measured value, the output unit thus comprises a measuring signal which is modulated on a carrier frequency or the resonant frequency of the capacitor C2 and the inductance of the transformer. By the receiver 3 ' the measurement signal is demodulated.

9 shows a variant in which the external energy is provided by a high-frequency circuit comprising a high-frequency receiving unit with an antenna, and converts an external transmission signal according to an RFID principle into electrical energy for supplying the electronic circuit. The example illustrates load modulation of a carrier signal by a vortex signal (such as RFID).

The flow meter unit 2 '' has a sensor with a load modulation or a piezoelectric element 13 on. The circuit includes a Modulation transistor TR, driven by the piezoelectric element and with an antenna 20 connected is.

The stationary unit 3 '' has a transmitter 21 with a transformer T3, an antenna 22 and a fixed transmission frequency. The antenna impedance changed by the transistor TR results in that at the receiver 24 incoming signal strength is varied. The antenna 23 is assigned to the recipient. The recipient 24 also has a diode D3, a demodulation F and an evaluation 4 ,

The example also describes a method of measuring water flow with a flow meter.

The basic idea of the invention is basically that the value of the "electrical" energy generated by a PVDF film is dependent on the flow rate in a known manner.

The invention is not limited to this example; The sensor is also conceivable to arrange in the supply line of the faucet. Also can each be in the hot water supply 25 and the cold water supply 26 a sensor can be present so that the cold water and hot water consumption can be recorded separately.

LIST OF REFERENCE NUMBERS

1

plumbing fixture

2

Flow Sensor

2 '

Electronic switch

2 ''

Flowmeter unit

3 '

receiver

3 ''

Stationary unit

4

evaluation

5

Flowmeter

6

casing

7

outlet opening

8th

external thread

10

circuit board

11

output unit

12

transmission unit

13

piezo element

14

disturbing body

15

sensor element

16

whirl

17

transmitting antenna

18

receiving antenna

20

First antenna

21

transmitter

22

Second antenna

23

Third antenna

24

receiver

25

Hot water supply

26

Cold water supply line

S1, S2

sawtooth

HF1, HF2

high-frequency vibrations

F

filter

TR

transistor

T1-T3

transformers

C1, C2

capacitors

D1-D3

diodes

Z-D

Zener diode

A

high flow

B

low flow

F

PVDF film

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 3328782 A1 [0003]

Claims (8)

Flow meter ( 5 ) comprising a housing through which a liquid or a gas flows ( 6 ) with an inner circumferential surface, characterized in that the housing ( 6 ) has a PVDF film (F) arranged in an annular manner on the inner circumferential surface for generating electrical energy, wherein an electronic circuit ( 2 ' ) is provided with an output device which is electrically connected to the PVDF film (F), wherein by the output device, a value for the flow rate is given, which is dependent on the electrical energy generated by the PVDF film (F). Flowmeter according to claim 1, characterized in that the PVDF film (F) is folded several times. Flowmeter according to one of the preceding claims, characterized in that the electrical energy generated by the PVDF film (F) is stored in a memory. Flow meter according to one of the preceding claims, characterized in that the housing is part of a sanitary fitting. Flow meter according to one of the preceding claims, characterized in that in the region of the PVDF film (F) a disruptive body ( 14 ) is arranged in the housing. Flow meter according to one of the preceding claims, characterized in that the PVDF film is screwed annularly on the inner circumferential surface of the housing. Method for measuring water quantity with a flow meter ( 5 ) according to any one of the preceding claims. Use of a PVDF film (F) arranged annularly in a housing through which a gas or liquid flows to determine the flow rate.

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