DE202008007991U1 - Dosing device for precise high-speed dosing of liquids - Google Patents

Abstract

Dosing device (10) for the precise dosing of liquids, comprising
- A piezoelectric tilting element (11) which, when activated, performs a tilting movement (α);
- A lever arm (13) which is connected at a first end (13.1) with the piezoelectric tilting element (11) to increase the tilting movement (a);
- A dosing unit (29) having a nozzle (21) and a pin (25) for closing a nozzle opening (23);
- A supply area (19) for introducing the liquid into the dosing unit (29);
wherein the pin (25) is connected to a second end (13.2) of the lever arm (13) such that the amplified tilting movement (β) is translated into a lifting movement (Δ) of the pin (25) with respect to the metering unit (29) and wherein the lifting movement (Δ) of the pin (25) with respect to the metering unit (29) releases the nozzle opening (23) as soon as the piezoelectric tilting element (11) is activated
characterized in that
- The dosing device (10) a piezo unit ...

Description

Field of the invention

object The invention is a metering device for the precise Dosing of liquids.

Background of the Invention, Prior Art

The precise dosing of liquids is a difficult one Task, especially if the dosage at a great speed must be executed. The viscosity of the liquid, which must be dosed, also plays an important role, because a For example, highly viscous adhesive is becoming increasingly difficult to treat is as an easily flowable substance. Different solutions are known that allow a quick and precise dosage. Some of these solutions bring a piezoelectric unit for use. The piezoelectric unit of these devices comprises a piezoelectric crystal, which, when connected by electricity is activated, expands. One type of pen is mechanical with connected to this piezoelectric crystal. By this stretching of the piezoelectric crystal, the pin closes a kind of Nozzle opening through which the liquid exit. This arrangement allows a high frequency dosage, because a piezoelectric crystal changes shape at a very high frequency can. The application of these arrangements, with a direct mechanical Connection between a piezoelectric crystal and the pin, the a nozzle opening closes but is limited because the movement of a piezoelectric crystal is very small. The movement is typically on the order of magnitude of 0.1% of the size of the piezoelectric crystal. That means that the space between the nozzle opening and the pen must be very small. This means that z. B. highly viscous Liquids with such arrangements are not precisely metered can be.

To overcome this limitation, various solutions employ a lever arrangement. These solutions comprise, instead of an ordinary crystal, a so-called piezoelectric tilting element which is connected to one end of a lever arm in order to mechanically strengthen the small movement of the piezoelectric tilting element by means of this lever arm. Two different piezoelectric tilting elements are off DE 198 55 221 and DE 196 46 511 known. Both propose stacks of piezoelectric bodies, with the various layers of these stacks reacting differently to current to cause the stacks to not simply expand but produce a tilting motion. If the tilting end of the piezoelectric tilting element is connected to the lever arm, then the other end of this lever arm can perform an amplified movement (in the sense of a larger stroke). In this case, the distance between the nozzle opening and the pin depends only on the length of the lever arm, that is, the gap can be set so large that even highly viscous liquids can flow through.

It It should be noted that this known arrangement with the lever arm and the piezoelectric tilting a very sensitive and precise Device is a very stable and robust unit got to. Due to the very small movement of the piezoelectric tilting element, need the dimensions of the lever arm, the pin and their Position with respect to the nozzle opening during manufacture be specified exactly. That's why this unit does not allow voting or adjustment by the user. That means that for any repair or adjustment dismantled the whole unit and must be sent back to the manufacturer. That means Of course, longer downtime and leads to a reduced flexibility.

The closed unit has the disadvantage that a replacement of Nozzles for use of the device for metering of liquids of different viscosities also not possible.

task The present invention is therefore a metering device for the precise high-speed dosing of liquids to provide the adjustable and thus for the dosage of Liquids with different viscosities suitable is.

Summary of the invention

These Task is according to the present invention in a Dosing solved by the fact that the metering device includes at least two different main parts related to one another adjustable and mechanically connected to a metering unit. The first main part is a piezo unit with a lever arm and a piezoelectric tilting element structurally similar may be with the arrangement described above. Most important is, that the piezo unit has the pin that opens the nozzle to close the dosing unit includes. It should be noted that according to the invention, the metering unit with the nozzle opening not part of the piezo unit. The second main part is a fastening device which is preferably part of the whole Liquid metering is. The fastening device includes a storage that holds the dosing unit. In a feeding area of the fixing device supplied to the dosing liquids in the dosing unit.

Of the The core of the invention is the way in which the dosing unit is the piezo unit connects with the fastening device. This connection allows that the position of the piezo unit manually adjustable with respect to the Fastening device is. This adjustment is preferred designed so that the dosing unit is not relative moves to the fastening device, but only the position of the piezo unit with respect to the dosing unit and thereby also with respect to the Fastening device is changed. As the pen component the piezo unit is and the nozzle opening part the dosing unit causes a movement of the piezo unit in With respect to the fastening device an equal movement of the Pin with respect to the nozzle opening. As a result can change the size of the nozzle opening and the space between the nozzle opening and the pen simply but precisely changed, respectively be set.

Of the most important advantage of the inventive arrangement according to The present invention is the flexibility. This means, that a single piezo unit in different application areas can be used and adjusted as needed. It should be noted that this setting is also made during operation can be. It is also an advantage that even the dosing unit can be replaced alone and then the new dosing unit can be reconnected to the same piezo unit. This Aspect is very important because normally the dosing unit is a Cost-effective item is that wears out over time becomes. The piezo unit is a much more expensive but at the same time much more durable Element. Therefore, it is preferred that the dosing unit be independent can be replaced by the piezo unit.

One Another advantage is that by this construction a heat separation is reached, which protects the piezo element from overheating.

beneficial way can also defects in the piezo unit, z. B. because of wear or other reasons, by the inventive Fine adjustment be corrected. The same fine adjustment of the distance between the piezo unit and the dosing unit allows an adjustment the dosing device for the dosing of liquids with different viscosities.

pictures

in the Following are further details and advantages of the invention using an embodiment and partially with reference described in detail on the drawing. The figure is schematized and not to scale. It shows:

1 a side view of an inventive dosing in assembly;

2 a side view of a piezoelectric unit according to the invention;

3A a side view of a fastening device according to the invention;

3B a cross section along the line AA 'of 3A a fastening device according to the invention;

4 a side view of a metering unit according to the invention.

Detailed description the embodiments

The invention relates to a metering device 10 for the precise dosing of liquids with different viscosities.

1 put the ready assembled dosing device 10 how it can be used. The dosing device 10 consists of two main parts, namely the piezo unit 15 and the fastening device 17 by means of the dosing unit 29 manually adjustable mechanically connected. The principle like the dosing device 10 This is described in more detail in the following sections after a detailed explanation of the main parts.

As in 2 shown, the first main part (piezo unit 15 called) mainly a lever arm 13 , a piezoelectric tilting element 11 that on a support 14 lies or sits, and a pen 25 (eg in the form of a needle).

The piezoelectric tilting element 11 is an arrangement of piezoelectric materials. Preferably, the tilting element comprises 11 a stack of piezoelectric bodies, wherein the various layers of this stack react differently to current to cause the stack does not simply expand, but produces a tilting movement. In the example of 2 , Includes the piezoelectric tilting element 11 two piezoelectric bodies ( 11.1 and 11.2 ) reacting under current conditions. That is, when the first piezoelectric body 11.1 shrinks, the second piezoelectric body expands 11.2 , This leads the whole tilting element 11 a tilting movement. Since the deformation of a piezoelectric body when applying a voltage is very small (the deformation can barely exceed one thousandth of the body dimension), the angle Δα of the possible tilting movement is also relatively small. To strengthen the very limited tilting movement, comes a lever arm 13 for use. A first end 13.1 the lever arm 13 is with the piezoelectric tilting element 11 firmly connected to the tilting movement to take over. The length L of the lever arm is always chosen so that the orthogonal movement ΔS (also called stroke movement) of the second end 13.2 the lever arm 13 big enough to make the necessary movement ΔS of the pen 25 to enable. If Δα the angle of the tilting element 11 and L is the length of the lever arm 13 from the first fulcrum 12.1 to the second pivot 12.2 are, then the movement ΔS = L · sin (Δα).

The pencil 25 , with the lever arm 13 is preferably connected by the piezo unit 15 be dissolved to put it in the dosing unit 29 to be able to plug in. The other end of the pen 25 that is not with the lever arm 13 is connected, preferably with a nozzle seal 16 equipped. This nozzle seal 16 allows when the piezoelectric tilting element 11 is activated, with the pen 25 the nozzle opening 23 the nozzle 21 close.

The support 14 (also called frame) has two functions. On the one hand, it carries the piezoelectric tilting element 11 and on the other hand, it provides a mounting area 18 for the dosing unit 29 ready.

In the preferred embodiment of the invention, this attachment area comprises 18 a fine thread 27 ' that with a corresponding fine thread 27 the dosing unit 29 an adjustable connection between the piezo unit 15 and the dosing unit 29 forms. It should be noted that the pin 25 through this attachment area 18 extends through, that is the attachment area 18 must necessarily include a channel or hole larger than the pin 25 ,

In other embodiments, there are also other solutions for the adjustable connection between the piezo unit 15 and the dosing unit 29 , such as slats with certain thicknesses to be inserted between the two parts. The specific solution chosen for the adjustable connection should not be construed as limiting.

In a further embodiment of the invention, the support comprises 14 also a section 33 which interacts with a corresponding pin 35 the fastening device 17 a rotation (in the sense of rotation) of the piezo unit 15 with respect to the fastening device 17 prevented.

3A shows a side sectional view of the preferred embodiment of the fastening device 17 , The main role of this fastening device 17 is a stable, robust attachment point for the dosing unit 29 and therefore also for the piezo unit 15 provide. Preferably, the fastening device 17 Part of a complete liquid dosing system. In this case, the fastening device comprises 17 a feed area 19 , which is used to introduce the liquids to be dispensed. This feed area 19 leaves the liquids to be dispensed, through appropriate supply holes 39 the dosing unit 29 , in the dosing unit 29 and until the nozzle opening 23 the nozzle 21 reach.

To the role of a stable, robust attachment point for the dosing unit 29 to meet, includes the fastening device 17 continue a storage 31 (or a corresponding receptacle), which is exactly for the dosing unit 29 is adjusted. This storage 31 or receptacle is preferably on the mounting housing 37 educated.

In the preferred embodiment of the invention, this is storage 31 or recording so expanded that they are the dosing unit 29 Keeps stable vertically and horizontally, but it allows the dosing unit 29 to turn around a vertical axis A. This storage 31 or receiving is in this case by means of an annular edge 41 realized that a rotation of the dosing unit 29 allowed, but at the same time carries their weight. The rotatability of the dosing unit 29 is only necessary if the adjustable connection between the piezo unit 15 and the dosing unit 29 by means of the fine thread 27 . 27 ' or other rotating solutions is realized.

In a further embodiment of the invention, the support comprises 14 also a section 33 to a twisting of the piezo unit 15 with respect to the fastening device 17 to prevent. The fastening device 17 includes a pin 35 in the neckline 33 the piezo unit 15 intervenes.

3B shows a cross section along the line AA 'of 3A the fastening device 17 according to the invention. On this figure you can also see how the storage 31 or inclusion in the mounting housing 37 is trained.

• a. eine verstellbare Verbindung zwischen der Piezoeinheit 15 und der Befestigungsvorrichtung 17 zu bilden;
• b. die zugeführte Flüssigkeit präzise durch die Düsenöffnung 23 der Düse 21 zu dosieren oder abzugeben;
• c. eine thermische Isolation zwischen der Piezoeinheit 15 und der Befestigungsvorrichtung 17 und dadurch dem Zuführbereich zu bieten.

In 4 is a schematic side view of the dosing unit 29 shown. This has three different roles:

• a. an adjustable connection between the piezo unit 15 and the fastening device 17 to build;
• b. the supplied liquid precisely through the nozzle opening 23 the nozzle 21 to dose or deliver;
• c. a thermal insulation between the piezo unit 15 and the fastening device 17 and thereby to provide the feed area.

The first roll is through the fine thread in the preferred embodiment of the invention 27 and a supporting edge 31 ' in storage 31 or recording fits, executed. The fine thread 27 fits in the corresponding fine thread 27 ' the piezo unit 15 to fine tune the piezo unit 15 with respect to the fastening device 17 to allow. By means of the annular edge 41 , the dosing unit can 29 turned around the vertical axis A and thus the fine thread 27 be screwed together or apart.

To the supplied liquids from the feed area 19 into the dosing unit 29 derive the dosing unit 29 with feed holes 39 fitted. The number and size of these feed holes 39 are adjusted so that regardless of the angular position of the dosing unit 29 around the axis A, at least one of these feed holes 39 at least partially with the feed area 19 is brought into overlap. This allows a continuous supply of liquids regardless of the adjustment of the piezo unit 15 with respect to the fastening device 17 through the dosing unit 29 ,

The interior of the dosing unit 29 is then designed so that the radially introduced from the outside liquid in the nozzle 21 and through the nozzle opening 23 can emerge undisturbed.

The thermal insulation of the piezo unit 15 from the fastening device 17 is by means of the dosing unit 29 achieved in that it is preferably made of thermally insulating material or equipped with a thermally insulating coating.

In a preferred embodiment of the invention, the nozzle is 21 around a replaceable nozzle 21 that can easily be changed by the user himself after use. Preferably, the replaceable nozzle 21 also permitted with own fine adjustment means. This fine adjustment means is preferably by means of another fine thread 43 executed.

• a. zuerst wird die Piezoeinheit 15 mittels der Dosiereinheit 29 mit der Befestigungsvorrichtung 17 verbunden;
• b. der Abstand ΔV der Piezoeinheit 15 von der Befestigungsvorrichtung 17 wird mittels des Feingewindes 27 und/oder des weiteren Feingewindes 43 so eingestellt, dass der Stift 25 die Düsenöffnung 23 dicht schliesst;
• c. in diesem Zustand, der auch Ruhezustand der Dosiervorrichtung 10 genannt wird, ist die Düsenöffnung 23 der Dosiereinheit mittels des Stiftes 25 geschlossen und es wird vorzugsweise keine Flüssigkeit an den Zuführbereich 19 geliefert;
• d. beim Einschalten einer Pumpe der Dosiervorrichtung 10 entsteht ein Flüssigkeitsdruck der in dem Zuführbereich 19;
• e. um Flüssigkeit durch die Düsenöffnung 23 abgeben zu können, wird das piezoelektrische Kippelelement 11 der Piezoeinheit 15 bei Bedarf aktiviert;
• f. auf diese Aktivierung hin führt das piezoelektrische Kippelelement 11 eine Kippbewegung aus, die durch den Hebelarm 13 in eine orthogonale Bewegung ΔS des Stiftes 25 umgewandelt wird;
• g. wenn der Stift 25 im Folge der Aktivierung des piezoelektrischen Kippelements 10 die Düsenöffnung 21 öffnet, tritt die unter Druck eingelieferte Flüssigkeit aus;
• h. wenn das piezoelektrische Kippelement 11 deaktiviert ist, dass heisst der elektrische Strom unterbrochen ist, kehrt das piezoelektrische Kippelement 11 in die Ausgangsposition zurück und damit schliesst der Stift 25 die Düsenöffnung wieder ab, und der Flüssigkeitslaustritt wird gestoppt.

The functioning of the whole dosing device 10 is now based on 1 explained step by step:

• a. First, the piezo unit 15 by means of the dosing unit 29 with the fastening device 17 connected;
• b. the distance .DELTA.V of the piezo unit 15 from the fastening device 17 becomes by means of the fine thread 27 and / or the further fine thread 43 adjusted so that the pin 25 the nozzle opening 23 tightly closes;
• c. in this state, the idle state of the metering device 10 is called the nozzle opening 23 the dosing unit by means of the pin 25 closed and it is preferably no liquid to the feed 19 delivered;
• d. when switching on a pump of the metering device 10 a fluid pressure arises in the feed area 19 ;
• e. to liquid through the nozzle opening 23 to be able to deliver, the piezoelectric Kippelelement 11 the piezo unit 15 activated as needed;
• f. The piezoelectric tilting element leads to this activation 11 a tilting movement by the lever arm 13 in an orthogonal movement ΔS of the pin 25 is converted;
• G. if the pin 25 as a result of the activation of the piezoelectric tilting element 10 the nozzle opening 21 opens, the supplied under pressure fluid exits;
• H. when the piezoelectric tilting element 11 is deactivated, that is, the electric current is interrupted, the piezoelectric tilting element returns 11 back to the starting position and thus closes the pen 25 the nozzle opening again, and the liquid outlet is stopped.

It It should be noted that steps e) to h) have a high frequency can be repeated. The highest frequency, The achievable depends on the one hand on the viscosity the liquid and on the other hand from the inertia of the piezostack. There are frequencies up to 3MHz available. It is obvious that such frequencies only with piezoelectric Devices are possible and conventional solutions can only reach lower frequencies, the more Magnitudes are lower.

If the nozzle opening 23 glued or damaged, the nozzle can 21 be replaced individually. After the dosing device 10 readjusted, the whole device can be used again in a short time. Even if the whole dosing unit 29 it has become difficult or it is possible to change only this fairly simple and inexpensive unit. This is much cheaper than before, since you had to replace or repair the conventional device with conventional piezoelectric dosing even with small deficiencies.

Even if the same metering device 10 is to use with different liquids, is a change of dosing 29 and a short fine adjustment sufficient. All these aspects are very important because the piezo unit 15 is a very sensitive and precise device and does not allow adjustment / adjustment itself.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 19855221 [0003]
• - DE 19646511 [0003]

Claims (7)

Dosing device ( 10 ) for the precise metering of liquids, comprising - a piezoelectric tilting element ( 11 ) which, when activated, performs a tilting movement (α); - a lever arm ( 13 ), which is at a first end ( 13.1 ) with the piezoelectric tilting element ( 11 ) is connected to increase the tilting movement (a); - a dosing unit ( 29 ) with a nozzle ( 21 ) and a pen ( 25 ) for closing a nozzle opening ( 23 ); A feed area ( 19 ) for introducing the liquid into the dosing unit ( 29 ); the pen ( 25 ) with a second end ( 13.2 ) of the lever arm ( 13 ) is connected so that the increased tilting movement (β) in a stroke movement (Δ) of the pin ( 25 ) with respect to the dosing unit ( 29 ) and wherein the lifting movement (Δ) of the pin ( 25 ) with respect to the dosing unit ( 29 ) the nozzle opening ( 23 ) as soon as the piezoelectric tilting element ( 11 ) is characterized in that - the metering device ( 10 ) a piezo unit ( 15 ) and a fastening device ( 17 ), - the dosing unit ( 29 ) the piezo unit ( 15 ) with the fastening device ( 17 ) mechanically connects, - the piezo unit ( 15 ) through the dosing unit ( 29 ) manually adjustable with respect to the fastening device ( 17 ) is mounted to a fine positioning of the pen ( 25 ) with respect to the nozzle opening ( 23 ). Dosing device ( 10 ) according to claim 1, characterized in that the dosing unit ( 29 ) as a heating barrier between the piezo unit ( 15 ) and the fastening device ( 17 ) serves. Dosing device ( 10 ) according to one of claims 1 or 2, characterized in that: - the fine positioning by means of a fine thread ( 27 ) is reached; and - the dosing unit ( 29 ) in the fastening device ( 17 ) is stored so that the dosing unit ( 29 ) is rotatable about a vertical axis (A). Dosing device ( 10 ) according to claim 3, characterized in that: - the dosing unit ( 29 ) Feed holes ( 39 ) passing through the feed area ( 19 ) supplied liquid into the dosing unit ( 29 ) derives; and - the number and size of the feed holes ( 39 ) is adjusted so that, regardless of the angular position of the dosing unit ( 29 ) with respect to the axis (A) at least one of these feed holes ( 39 ) at least partially with the feed area ( 19 ) is brought into overlap. Dosing device ( 10 ) according to one of claims 1 to 4, characterized in that the nozzle ( 21 ) and / or the dosing unit ( 29 ) are interchangeable. Dosing device ( 10 ) according to one of claims 1 to 5, characterized in that the nozzle ( 21 ) another fine thread ( 43 ) for additional fine adjustment of the pen ( 25 ) with respect to the nozzle opening ( 23 ). Dosing device ( 10 ) according to one of claims 1 or 2, characterized in that the fine positioning is achieved by means of lamellae with certain thicknesses which are between a support ( 14 ) of the piezo unit ( 15 ) and the fastening device ( 17 ) are inserted.