DE102006010328A1 - Piezoelectric sensor for e.g. determining impulses of individual drops impinging on measuring surface, has crystal converting impulse of drop into electrical signal, where amplitude of signal is expression of impulses of drops - Google Patents

Abstract

The sensor has a piezoelectric crystal for converting impulse of drop through compression into an electrical signal, where amplitude of the signal is an expression of the impulses of drops and piezoelectric units made of piezoelectric crystal. A cover plate protrudes over a base plate, where a measuring surface is grounded off through a tension spring to the base plate. The measuring surface exhibits the cover plate to overlie on the piezoelectric units. An independent claim is also included for a cover plate for use in sensor.

Description

The The invention relates to a piezoelectric sensor for measuring Precipitation events and for determining the momentum of each individual the measuring surface striking, drop.

Around To characterize precipitation events of different origins and to classify suitable measuring instruments are needed. Conventional measuring devices like the Measuring cylinder or the rain seesaw serve to determine the total amount of precipitation.

visual Measuring systems can by means of cameras or lasers single drops or snowflakes optically measure.

Furthermore Precipitation radars exist mainly for weather research be used by measuring the water content in large volumes of air based on their radar reflectivities determine.

The Joss-Waldvogel Distrometer determined by means of a sensor based the induction principle and a separate processor single drops of water mechanically.

conventional Measuring device and precipitation radars are unable to determine the total precipitation volume to further characterize the precipitation event and analyze. About that In addition, the precipitation radar and the optical measuring systems mostly localized and extremely inflexible, susceptible to faults, maintenance-intensive and very expensive.

Furthermore are all listed Measuring systems only for few special fields of application are suitable and, with the exception of Measuring cylinder and rain seesaw, only for natural precipitation events applicable.

task It is the object of the invention to present a cost-effective, robust measuring device, which is not susceptible to interference, for precipitation events. The measuring device should to be able as possible precise, to register individual drops and their mass, diameter or Reproduce volumes. The obtained signals generated, for example used to create a spectrum of droplet size distribution. Furthermore it should be possible compact, non-mobile and flexible in use for precipitation of all kinds Origin, both natural as well as artificial generated, measure.

• I. Den mechanischen Teil Messsystems stellt der Piezosensor dar. Mit dessen Hilfe ist es möglich, jedes einzelne Niederschlagsereignis, dem Auftreffen eines Tropfens auf der Messempfindlichen Oberfläche zu registrieren. Dabei gibt der Sensor nicht nur Auskunft über die Tropfenanzahl durch die Anzahl der Signale, sondern drückt darüber hinaus den Impuls des Tropfens in Form der Amplitude aus.
• II. Die durch den Sensor (I) erzeugten Signale werden anschließend durch einen Operationsverstärker verstärkt.
• III. Daraufhin werden die verstärkten Signale in den analogen Line-Eingang der Soundkarte eines Computers oder alternativ in einen beliebigen Audiorecorder eingespeist.

This object is achieved by the incorporation of the piezoelectric sensor in a three-part measuring system, as in 1 illustrated and described below, taking into account the features of claim I, solved:

• I. The mechanical part of the measuring system represents the piezoelectric sensor. With its help it is possible to register every single precipitation event, the impact of a drop on the measuring surface. The sensor not only provides information on the number of drops by the number of signals, but also expresses the pulse of the drop in the form of the amplitude.
• II. The through the sensor ( I ) are then amplified by an operational amplifier.
• III. The amplified signals are then fed into the analog line input of a computer's sound card or alternatively into any audio recorder.

The Records can then through Any evaluation software will be processed on the computer. When recording through an alternative audio recorder it applies previously this on a computer over to feed the analog line input of the sound card.

The free choice of recording device, the evaluation software and the evaluation parameter offers a High flexibility and versatile uses.

The allow small external dimensions of the piezoelectric sensor the location independence and mobility of the measuring system.

By the use of simple materials and cheaper components for construction the piezo sensor result favorable Material costs.

By the simple structure and the choice of robust single components is one high weather resistance and reliability guaranteed.

Of the simple mechanical design and low mechanical stress favor one low maintenance intensity.

It becomes a high measuring precision and a high quality of information through the free choice of the evaluation software, the evaluation parameters and the form of representation allows.

embodiments are shown in the drawings and will be described in more detail below.

1 : Representation of the basic form with 3 piezo elements

2 : Representation of the basic form with 4 piezo elements

3 : Illustration of a piezo lighters fuze

4 : Illustration of a prepared piezo lighters fuze

5 : Exploded view of an example of the structure of the piezoelectric sensor

The geometric basic form:

When choosing the basic shape, a geometric shape adapted to the formation of the piezo elements must be selected. In the optimal formation of three piezoelectric elements on three axes with an intermediate angle of 120 °, it is important to choose the equilateral triangle as a geometric base (see 2 ). But even formations with more than three, for example four, piezo elements are possible (see 3 ). In this case, it is necessary to choose a geometric basic shape whose number corresponds to the corners of the number of piezo elements.

The piezo elements:

Piezoelectric elements of any diameter and thickness can be selected as the piezo elements. By stacking several slices it is possible to optimize the sensitivity. A cost-effective option is the use of piezoelectric elements from lighter lighters. For this it applies this according to the 4 to prepare.

The structure:

The Basis is one possible strong base plate made of a suitable metal, whose side length the effective measuring surface certainly. The base plate is in favor of low resonance, stability and stability chosen massively. She owns in the extreme Corners each have a bore the dimensions of the piezoelectric elements, or corresponds to the metal cylinder of the lighter lighter. In this hole are the piezoelectric elements used. The holes are chosen so that the metal cylinders sit very tightly and little leeway on horizontal Level have. About that it also ensures that the bottom of the piezoelectric elements on the bottom of the Bore rests. The holes of the holes are chosen so that the piezo elements in all three corners the same and as deep as possible sit around the movement scope preferably to keep low and a flush Secure the cover plate to rest.

The Shielded connection cables of the elements are common or separate By drilling through the base plate down from the device. The used connection cables If necessary, be fixed on the plate by adding additional Through holes for Cable ties are made. Furthermore, feet can be mounted to sufficient Ground clearance and protection against interference guarantee.

Also located on the underside of the base plate a central perforation next to the left and right each made another hole is. Here is a metal hanger flush inserted, to which a tension spring is hung.

The other end of the tension spring is possible on the cover plate as possible mounted light and low-resonance material.

For this is a small screw with a hole in the thread in the central Point of the cover plate inserted. The screw can be replaced by a small one Nut and washer are fixed.

The Cover plate also has three side skirts made of metal. Prevent these the direct penetration of water and improves the shielding against interference. For the best possible shielding to achieve water and radiation, the corners are in addition to Silicone sealed and the cover plate over the spring along with the base plate grounded.

As an example of a construction can 5 serve.

Claims (7)

Piezoelectric sensor for measuring precipitation events and for determining the momentum of each individual drop striking the measurement surface, characterized in that the pulse of the drops is converted into an electrical signal by compression of piezoelectric crystals and the amplitude of the signal is the expression of the momentum of the drops characterized in that three or more piezoelectric elements are used, characterized in that the piezoelectric elements consist of one or more piezoelectric crystals and characterized in that the measuring surface is a resting on the piezoelectric elements cover plate. Piezoelectric sensor according to claim I, characterized that the measuring surface is pulled down by a tension spring to the base plate. Piezoelectric sensor according to claim I or II, characterized in that the piezoelectric elements are respectively embedded in the corners of the base plate, wherein the number of piezoelectric elements corresponds to the number of corners of the base plate. Piezoelectric sensor according to one of the preceding claims, characterized characterized in that the cover plate protrudes slightly beyond the base plate. Piezoelectric sensor according to one of the preceding claims, characterized characterized in that side skirts mounted on the measuring surface are that protect against the ingress of water and interference. Piezoelectric sensor according to one of the preceding claims, characterized characterized in that the tension spring above by a screw with hole in Thread in the central point of the measuring surface and below, through a central Through hole through the base plate, on the bottom on a recessed bracket hooked becomes. Piezoelectric sensor according to one of the preceding claims, characterized characterized in that the measuring surface made of a composite panel of aluminum and PVC, aluminum and polystyrene or other metal and plastic or foam combinations consists.