EP2799141B1 - Liquid handling device to be attached to a bottle - Google Patents

Description

The invention relates to a bottle attachment device for handling liquids with the features of the preamble of claim 1.

These devices involve the accurate metering and delivery of fluids from a storage bottle or other storage container, with accurate metering in picking up a partial fluid volume from the storage bottle or the like into the device and / or dispensing a partial fluid volume out of the device to the outside into a container.

Bottle attachments of the type in question are in particular burettes and dispensers. Such bottle top devices are widely used in chemistry, biology and pharmacy in the laboratory and in production.

The term "liquid" in the present context refers to liquids which are used extensively in chemistry, biology, pharmacy, etc. in the laboratory and in production, in particular liquids having a relative viscosity of up to about 300 (viscosity based on the viscosity of water under normal conditions ). It is therefore the fluid range from very fluid to slightly viscous.

A manually operated burette is used in titration to determine the unknown amount of a solute from the consumption of a reagent liquid of known concentration. To ensure proper and economic analysis work, a burette is required to quickly and accurately dispense and display the particular amount of fluid. High demands are placed on the precision of the liquid dispensing and on the operator safety (General Catalog 600 "Laboratory Equipment from Brand" of BRAND GMBH + CO KG 09/01, No. 9963 00, "Burette Digital III", pages 27 to 34).

Comparable requirements are also found in bottle top dispensers, especially those with digital display of the desired dispensing volume ( DE-A-35 16 596 ; General Catalog 600 "Laboratory Equipment from Brand" of BRAND GMBH + CO KG 09/01, No. 9963 00, "Dispensette", pages 9 to 18).

Here and below, the bottle top device is described in its operating position, that is mounted in its position on a storage bottle and aligned substantially vertically.

In the valve block is regularly a suction valve, which allows to suck liquid from the storage bottle by means of a suction pipe. Approximately horizontally from the valve block, an exhaust duct extends with an exhaust valve located therein. Since the discharge line protrudes approximately horizontally from the valve block and often still carries an additional switching valve, this is the side from which an operator works with the bottle top unit. This page will be referred to below as "front" or "front". The opposite side is the "back" or "back". In the case of a bottle-top device, a display with corresponding operating elements is regularly at the front.

A well-known bottle attachment for handling liquids (see the General Catalog 600 "burette Digital III", as stated above) is characterized in that the cylinder-piston arrangement is covered by a closed top outer housing from above. This outer housing moves together with the piston rod relative to the cylinder upwards. To accomplish this, located on the cylinder a vertically extending rack, with a pinion on a drive shaft which is mounted in the outer housing, meshes. The piston drive this bottle attachment device is designed for manual operation and therefore carries the drive shaft there at both ends outside the outer housing each have a manual control knob.

An advantage of this Flaschenaufsatzgerält that just the outer casing is closed to the cylinder-piston assembly. But this is bought with the movement of the entire outer housing with all assemblies arranged therein. In particular, in the very upwardly driven position of the outer housing, such an arrangement of bottle top unit and storage bottle has a considerable tendency to tilt.

A similar conception with appropriate tendency to tilt also show other bottle attachment devices ( DE-A-35 16 596 . DE-A-35 34 550 ).

Another solution is found in a bottle attachment in the form of a piston burette with digital display, in which a the piston drive, the display, a sensor assembly and a control electronics receiving housing in solid, non-variable relative position to the valve block ( DE-C-35 01 909 ). From this bottle top device, the teaching of the invention is based. Here, the outer housing is not closed, but the piston rod passes through the housing from bottom to top already in the lowest position of the piston in the cylinder. When the piston is raised, the piston rod moves up out of the housing. By an upwardly connected bellows while the entry of dirt and dust on the passage opening for the piston rod is prevented in the housing.

In the above-mentioned bottle attachment device, the tendency to tilt is slightly lower than in the previously described bottle attachment device, since the outer housing is not displaced as a whole relative to the valve block. But this is bought with the open-top housing.

In all bottle top devices of the type in question are operating buttons on the front of the outer housing. An actuation of the operation keys requires holding the outer housing, at least if you want to prevent tilting the arrangement of bottle top unit and storage bottle safely. This is especially important for small volume storage bottles.

For the accuracy of a bottle attachment of the type in question many influences of construction and handling of importance. Among other things, significant is the stick-slip effect, so overcoming the static friction of the piston in the cylinder in the transition to sliding friction during adjustment. This is where many design factors of the bottle top device play their part. User friendliness and operator safety are essential boundary conditions.

For user-friendliness and operator safety, the previously described design features of the known bottle top devices are relevant. For accuracy and operator safety also the boundary conditions are to be considered, under which bottle top devices of the type in question are often used.

At a very high resolution of the data acquisition, which can be achieved, for example, due to a particularly convenient mechanical construction of a device of the type in question, effects gain an influence on the measurement results, which have so far been disregarded. In particular, comes it on the play of the piston rod in the piston drive. The lateral play in the piston drive allows lateral inclinations of the piston rod relative to the piston, which can falsify the measurement result at a high resolution.

All of the above-mentioned devices have in common that small and very small amounts of liquid must be precisely determined. In the prior art from the DE-C-35 01 909 , from which the invention proceeds, a high-precision measuring arrangement with displacement measuring strip and sensor arrangement is already provided, in which the play of otherwise necessary reduction gears of a measuring system of classical technology is eliminated ( DE-A-101 06 463 ). The immediate arrangement of the displacement measuring strip in this piston burette on the piston rod and the immediate reading there by means of the sensor of the sensor arrangement, a significant source of error is eliminated.

In this device, it is first proposed that the measuring strip is an optical scale and the sensor arrangement is an incident light system. As an alternative, it is proposed that the measuring strip is part of a capacitive system, which also includes the sensor. Opposing electrodes are arranged so that two pairs of measuring capacitances for measuring the relative movement between the measuring strip and the sensor are formed.

As a third variant, it is proposed in this device that the piston rod carries a magnetic strip. Adjacent to the piston rod, a reading head is fixedly provided in the housing, which is aligned with the magnetic measuring strip and separated therefrom by a gap. An electronic control circuit is coupled to the read head, which reads the measurement information on the magnetic strip and injects appropriate pulses into the control circuit. This converts the pulses and controls a digital display, which in turn indicates the volume of liquid dispensed based on the relative movement between the piston and cylinder.

In the above direct arrangement of the displacement measuring strip on the piston rod as in DE-C-35 01 909 The measuring strip is also driven into the cylinder. The cylinder inner wall is wetted in this area with the liquid to be metered. The interior is encapsulated by sealing measures, so that even the sensor arrangement resulting vapors may be exposed to intense.

If sections of magnetized displacement measuring strips are used, an incremental position determination of a piston rod and thus of the piston in the cylinder can also be realized.

For the evaluation and the corresponding software in an incremental position determination, it is known to supply the periodic, phase-shifted analog signals (sin; cos) supplied by the sensor to the evaluation circuit and subject them to interpolation in accordance with an interpolation table. The periodic analog signals are digitized in the evaluation circuit and the digital values are normalized for assignment to the interpolation table. This requires comparatively fast, power-intensive and relatively expensive analog / digital converters etc. ( DE-C-34 17 016 ).

Because the section number of the displacement gauge is limited for mechanical reasons (typically one section is about 1 mm long), a significantly higher resolution of the measurements can only be achieved by directly evaluating the analog sinusoidal (and cosine) signals rather than just their zero crossings to use. One has a sinusoidal signal and a cosinusoidal signal, because one usually operates with two magnetic field sensitive encoders which are offset in pitch of the displacement gauge so as to emit two signals offset by a quarter of a period.

For the previously described devices for measuring handling of small amounts of liquid, the power consumption is an essential criterion, the today commercially available devices with a battery over several years get along (General Catalog of the Applicant, ibid, page 31, "burette Digital III").

Previously known sensor arrangements and their associated evaluation circuits have a power consumption of well over 5 mA to about 25 mA in operation at an interpolation rate between 200 and 1000. This requires much more powerful batteries or rechargeable batteries than is usual today, which would only last a few hours in such a circuit.

The teaching of the present invention is based on the problem of further increasing the measuring accuracy of a bottle-top device of the type from which the invention is based.

The above-indicated problem is solved in a bottle attachment with the features of the preamble of claim 1 by the features of the characterizing part of claim 1.

It is crucial that, in the case of an optical measurement, the surface of the optically active measuring strip facing the sensor forms a plane which lies on the longitudinal central axis of the piston rod. In the case of a measuring system based on a magnetic field measurement, it applies correspondingly that the sensor detecting the magnetic field of the measuring strip lies on the longitudinal central axis of the piston rod, that is to say it is positioned. In the case of a capacitive measurement, the longitudinal center axis of the piston rod should lie between the sensor-facing surface of the measuring strip and the sensor itself when the piston rod is in the set position.

Preferred embodiments and further developments of this teaching are subject matter of claims 2 and 3.

Further subclaims relate to the type of attachment of the measuring strip to the piston rod.

As already mentioned, it is advantageous to carry out the bottle attachment device largely resistant to chemicals. However, this is not just about the surfaces in contact with the liquid. In fact, corresponding vapors which can cause problems in the interior of the outer housing of the bottle-top device according to the invention result from corrosive or otherwise damaging liquids.

In the above-mentioned bottle attachment with a bellows is particularly problematic that the emanating from the wetting of the inner wall of the cylinder vapors can not escape. The space surrounding the piston rod is displaced by the piston in the suction process. This atmosphere escapes past the sensor system and occupies it. The permanent action of these vapors on such components in a closed and unactuated housing quickly leads to significant malfunction.

According to claim 8, the sensor is designed as a magnetoresistive sensor system, in particular based on the AMR effect, and the evaluation circuit has a largely highly integrated, cost-effective mixed-signal controller, which evaluates the converted analog sensor signals directly via an interpolation software.

Mixed-signal controllers are microcontrollers that connect various electronic processing functions, which are also suitable for evaluating the sensor signals via interpolation software, with the functions of an A / D converter. Thus, a mixed-signal microcontroller replaces a three-stage arrangement of A / D converter, processing stage with processing software and output stage. Such a mixed-signal microcontroller is regularly far cheaper to use at the signal level of AMR sensors than a three-stage arrangement. Microcontrollers are offered by different providers with different power spectra (see for example the Datasheet "MSP 430 x 33 x MIXED SIGNAL MICROCONTROLLERS", February 1998, Texas Instruments ). With a mixed-signal microcontoller you not only create a simple signal processing solution, but in particular a very low power consumption both during operation and when idle. (For detailed information, please refer to the relevant data sheets, in particular the previously mentioned data sheet.)

Mixed signal controllers can be realized in different versions, for example as PSoC (Programmable System on a Chip), as DSP (Digital Signal Processor) or as FPGA (Field Programmable Gate Array). The latter has a purely digital input transducer, allowing a discrete upstream A / D converter to turn the overall arrangement into a mixed-signal controller of the type described.

According to claim 10, it is of particular advantage if the evaluation by means of the evaluation circuit with an ON / OFF duty cycle of about 0.1 to about 0.02, preferably between about 0.05 and about 0.03, in particular with an ON Time from about 0.6 ms to about 0.1 ms, in particular between about 0.3 ms and about 0.15 ms. Furthermore, it appears to be particularly advantageous that the interpolation software operates at an interpolation rate between 200 and 1,000, in particular between about 400 and about 600, preferably about 500.

By using a corresponding duty cycle, it is possible to reduce the current consumption of the measuring system according to the invention to less than one tenth of the power consumption of the interpolation IC's prior art, namely down to less than 200 μA in operation.

Overall, it is possible to significantly optimize the measuring system based on a magnetic field measurement in a device of the type in question with the previously described inventive measures.

In the device according to the invention, a structure can be realized, which ensures safe operation and at the same time easy handling. The power consumption of the measuring system is low and the cost of production are also lower than with traditional bottle-top devices.

The solution of claim 12 has a displacement of at least one operating button of the display on the front of the outer housing on the top of the subject. It can be arranged on the top of the outer housing depending on the space and requirements but also two or even more buttons.

Here, the outer housing is closed on the top side and includes the cylinder-piston arrangement from above. The solution makes use of this fact known for decades to advantage for an optimized operation possibility of the bottle top attachment. An operating button, which is often used when working with the bottle top unit, can be actuated here by pressure from above. As a result, a quick and error-free operation is possible without a serious tilting moment is exerted on the bottle top unit and the storage bottle underneath. Unlike the arranged on the front of the outer case operating buttons thus no holding back the outer housing is required.

Preferably, the actuating button arranged on the upper side of the outer housing may be a single, large-area button bordering the outer housing at the edge.

Furthermore, it can be provided that in the outer housing, in particular in a receptacle provided in the outer housing for electronic devices, in particular for a populated circuit board, under the actuating button a circuit board is arranged, which carries a push button, which is actuated by the actuating button. Preferably, the board is then seated in a slot of the receiving compartment. The board may be connected to the circuit board via a film hinge, which is preferably formed by a circuit film web.

Taking into account the above-mentioned corrosive or otherwise damaging vapors, it is also recommended according to the alternative in claim 13, that the outer housing is provided with ventilation openings, which are arranged to achieve convection both centrally and / or down and on top of the outer housing.
In conjunction with the actuating button you can arrange overhead ventilation holes hidden under the operating button.
In the claimed bottle cap device, it is further expedient that the piston drive is designed for manual operation and has a drive shaft which carries at one end or at each end outside of the outer housing a manual operation knob and in that central ventilation openings are concealed under the hand operation knob or the hand operation knobs are arranged.
Furthermore, it is an interesting variant that lower ventilation openings are arranged at the edge close to the valve block under at least one protective cap.
The solutions according to the invention, which in particular increase operator safety, can be used in principle in the case of both previously treated types of bottle attachment devices, that is to say with a traveling outer housing and with an outer housing fixedly arranged on the valve block. The term "fixed" in this context means that the outer housing is not moved relative to the valve block in this variant, when the piston of the cylinder-piston assembly is moved. However, this outer housing may well be detachable from the valve block to perform repairs or cleaning or sterilization of the cylinder and / or the piston or other assemblies.
By actuating the top of the outer housing no liquid is discharged. On the one hand, the outer housing does not move when a force acting vertically from above is introduced. On the other hand, no protruding piston rod can be driven.

In principle, the measures explained above are to be realized with advantage in a bottle attachment device with a motor drive of the piston. There, however, occur in any case the tendency to tilt usually less than a manually operated bottle top attachment. Therefore, both variants of the present invention are of particular advantage in a bottle-top device designed for manual operation.

All previously discussed apparatus for measuring small quantities of liquid in the field of chemistry, biology, pharmacy, etc. in the laboratory, experiment and production have in common that they have a cylinder-piston arrangement for precisely receiving and dispensing partial liquid volumes. In a cylinder runs a sealed piston from which a piston rod is led up out of the cylinder. The movement of the piston rod is used to accurately determine the travel of the piston.

According to the teaching of claim 13, an optimization of the measuring system in devices of the type in question is achieved in that the sensor arrangement is arranged in a fully closed to the measuring strip receiving pocket. The sensor arrangement can optionally be cast in the receiving pocket with potting compound in the rear, in order to ensure an optimum protective effect for the sensor arrangement. Of course, this only works with a suitable measuring strip.

In a non-optical, in particular a magnetic field-sensitive sensor arrangement is concerned with a correspondingly magnetized measuring strip. An optical sensor arrangement uses an optical scale.

The gas volume in the interior surrounding the piston rod, which is displaced during absorption, now flows only past the sensor arrangement protected by the receiving pocket. It can no longer occupy the sensor as condensate and impair its function.

A suitable alternative has a wall portion of the receiving pocket, which is designed as a film. This film should be extremely thin and have a low permeability to the gases occurring. Such a thin film can even consist of transparent material, so that the sensor of the sensor arrangement can work optically.

According to a preferred teaching is provided in this context that the receiving pocket is provided with slot connections that allow an exact alignment of the receiving pocket on the measuring strip when installed in the device.

According to a further, particularly preferred embodiment it is provided that the sensor is arranged in the receiving pocket at its side facing the measuring strip behind a thin-walled wall portion of the receiving pocket. The sensor has been brought as close as possible to the gauge, without actually touching it, and while maintaining a gas-tight seal of the sensor assembly to the interior of the device.
Particularly preferably, the receiving pocket consists of a chemical-resistant plastic, in particular of PEEK.

Fig. 1

eine perspektivische Ansicht eines Flaschenaufsatzgerätes in Form einer digitalen Bürette auf einer Vorratsflasche,

Fig. 2

das Flaschenaufsatzgerät aus Fig. 1 in einem Vertikalschnitt von vorn nach hinten ohne Vorratsflasche,

Fig. 3

im Schnitt, in vergrößerter Darstellung, Ventilblock und Rahmen mit Einbauten des Flaschenaufsatzgerätes gemäß Fig. 2, mit derselben Schnittlage wie Fig. 2,

Fig. 4

die in Fig. 3 dargestellten Teile in einem Vertikalschnitt mit gegenüber Fig. 3 um 90° versetzter Schnittlage,

Fig. 5

das Flaschenaufsatzgerät aus Fig. 1 von hinten gesehen, die hintere Gehäuseschale abgenommen und die Deckel der Batteriefächer ebenfalls abgenommen,

Fig. 6

in vergrößerter Darstellung, jedoch in der gleichen Ausrichtung wie in Fig. 2, die Sensoranordnung in einer Aufnahmetasche,

Fig. 7

die Aufnahmetasche mit darin befindlicher Sensoranordnung in einer perspektivischen Ansicht schräg von hinten,

Fig. 8

ein Prinzipschaltbild eines AMR-Sensors, der als magnetoresistiver Sensor im Messsystem eingesetzt werden kann,

Fig. 9

eine Auswerteschaltung für einen solchen AMR-Sensor,

Fig. 10

ein Diagramm, das die Tastung bei dem bevorzugten Messsystem beispielhaft zeigt,

Fig. 11a

ein bevorzugtes Ausführungsbeispiel einer Zylinder-Kolben-Anordnung mit einer erfindungsgemäßen Messwerterfassung für eine magnetoresistive Messung mit in Sollstellung befindlicher Kolbenstange,

Fig. 11b

das System aus Fig. 11a, jetzt die Kolbenstange gegenüber der Sollstellung spielbedingt ausgelenkt,

Fig. 12

in vergrößerter Darstellung in Fig. 3 ähnlicher Ausrichtung einen Kolben mit Kolbenstange mit einem Messstreifen in besonders zweckmäßiger Anordnung.

The sensor of the sensor arrangement is expediently seated on a board inserted in the receiving pocket in an insertion guide, specifically on its front edge (see here the above explanations of the receiving pocket).
For all variants of the bottle-top device according to the invention, a particularly preferred selection for the stroke quotient, which is described in claim 15, applies.
Finally, the present bottle attachment device is particularly preferably a burette, so executed as a burette.
In the following, the invention will now be explained in more detail with reference to a drawing which represents only particularly preferred and not limiting embodiments. In the drawing shows

Fig. 1

a perspective view of a bottle attachment device in the form of a digital burette on a storage bottle,

Fig. 2

the bottle top unit off Fig. 1 in a vertical section from front to back without storage bottle,

Fig. 3

in section, in an enlarged view, valve block and frame with internals of the bottle top unit according to Fig. 2 , with the same cutting position as Fig. 2 .

Fig. 4

in the Fig. 3 shown parts in a vertical section with opposite Fig. 3 90 ° offset cutting position,

Fig. 5

the bottle top unit off Fig. 1 seen from behind, the rear housing shell removed and the lid of the battery compartments also removed,

Fig. 6

in an enlarged view, but in the same orientation as in Fig. 2 , the sensor arrangement in a receiving pocket,

Fig. 7

the receiving pocket with therein sensor assembly in a perspective view obliquely from behind,

Fig. 8

a schematic diagram of an AMR sensor that can be used as a magnetoresistive sensor in the measuring system,

Fig. 9

an evaluation circuit for such an AMR sensor,

Fig. 10

a diagram showing the keying in the preferred measuring system by way of example,

Fig. 11a

A preferred embodiment of a cylinder-piston assembly with a measured value detection according to the invention for a magnetoresistive measurement with located in the desired position piston rod,

Fig. 11b

the system off Fig. 11a , now the piston rod is deflected relative to the desired position due to the play,

Fig. 12

in an enlarged view in Fig. 3 similar alignment a piston with piston rod with a measuring strip in a particularly convenient arrangement.

Fig. 1 shows a preferred embodiment of a bottle attachment according to the invention for handling liquids, here in the form of a burette.

In general, for bottle attachments for handling liquids, so-called "liquid handling devices" on the general catalog of the applicant "600 General Catalog - Laboratory Equipment BRAND" 09/01, pages 9 to 34 may be referenced. There bottleneck dispensers and burettes are explained in construction and application.

Examples of burettes as bottle attachments have been given in the introduction ( DE-C-35 01 909 ; EP-B-0 096 088 ; DE-A-101 06 463 ; DE-A-35 16 596 ). Bottle-top dispensers emerge, for example, from the DE-U-88 00 844 and in particular the EP-A-0 542 241 , which will be discussed below.

For the bottle-top device, which is described below, the definitions from above and below as well as from the front and rear, which have been given in the introductory description. The bottle attachment is always in the in Fig. 1 illustrated position on a storage bottle, even if it is not shown in this position.

This in Fig. 1 It has an outer housing 2 and is a total of a mounting assembly 3, here a cap, attached to a bottle neck of the storage bottle 1, screwed here. At the top of the outer housing 2, aligned in front, there is a display 4 with a display field 5, in particular for a digital display, preferably with LCD elements, as well as with actuating elements, in particular actuating buttons 6.

From the outer housing 2 to the front protrudes a discharge line 7, which is arranged in the illustrated embodiment in an angle-shaped holder 8 and closed at the end by means of a cap 9 for closing and as drip protection.

Details of the bottle top unit will now be apparent from the sectional view in Fig. 2 ,

The illustrated bottle top unit has in the outer housing 2, first a valve block 10. At this is attached or integrally formed the already mentioned mounting assembly 3, with the fact of the valve block 10 is mounted on the storage bottle 1. At the same time then also the outer housing 2 is mounted on the storage bottle 1.

The illustrated and preferred embodiment shows the valve block 10 as a one-piece made of plastic, in particular made of chemical resistant plastic component, which is provided with a plurality of channels and internals. In detail, the construction largely corresponds to the valve block of Flaschenaufsatzdispensers, from the EP-A-0 542 241 is known and belongs to the prior art.

The mounting assembly 3 is designed as compared to the valve block 10 freely rotatable cap. In a downwardly directed recess of the valve block 10 is a suction valve insert 11, to which an intake line 12, which is shown shortened here for simplicity, is connected to the bottom of the storage bottle 1 into it. At the top closes to the intake valve insert 11 in the valve block 10 to an intake passage 13, from which at about half the height in Fig. 2 branched off to the right discharge channel 14. A discharge valve insert 15 is located in a recess of the valve block 10 on the discharge channel 14. This is part of a valve body 16 of a changeover valve 17 attached to the valve block 10. On the outflow side, the discharge line 7 adjoins the changeover valve 17 in the holder 8. In the sectional view in Fig. 2 the holder 8 is arcuate and leads the discharge line 7 in the same arc, so that the discharge opening facing downward. There it is closed with the cap 9.

The switching valve 17 has a valve body 16 rotatable about a vertical axis of rotation valve body 18, which also has a in Fig. 1 recognizable knob 19 can be adjusted by hand. Below the discharge valve insert 15 extends in the valve body 16, a return passage 20, which continues in the valve block 10 to a downwardly outgoing return line 21.

At the in Fig. 2 presented and in Fig. 1 recognizable position of the knob 19, the switching valve 17 is switched to passage, so that the discharge channel 14 is connected to the discharge line 7. In contrast, in a rotated by 90 ° position of the valve body 18, however, the discharge channel 14 with the return passage 20th connected, so that liquid in the circulation from the storage bottle 1 and the return line 21 is conveyed back into the storage bottle 1. More specifically, for the entire background of this so - called "back - dosing", please refer to the detailed explanations given in the EP-A-0 542 241 to get expelled.

The valve block 10 further includes near the back of a bottle venting line 22, which opens in a rearwardly, radially open plug receptacle 23. In the plug receptacle 23 there is a plug 24 closing this or a similar closure element, but having a small passage opening, so that the interior of the storage bottle 1 is connected via the bottle venting line 22 and this passage in the plug 24 with the ambient atmosphere. As a result, a pressure equalization in the storage bottle 1 is possible.

Am here integrally made of chemical resistant plastic material, such as PFA, existing valve block 10 is a preferably and also made of glass existing cylinder 26 fixed and sealed against the valve block 10 in a cylinder mount 25. Specifically, the cylinder 26 is compressed in the cylinder receptacle 25.

For information on various plastic materials with their abbreviations, reference is made to the relevant specialist literature and also to the above-mentioned general catalog of the applicant, in particular pages 224, 225.

In the cylinder 26 is a sealed therein running piston 27 with an upwardly out of the cylinder 26 led out piston rod 28. Above the cylinder 26 is a standing with the piston rod 28 in drive connection piston drive 29. The display 4 for each handled or even handling amount of liquid has already been mentioned above.

While in the area of the valve block 10, the illustrated bottle top unit is designed according to the already extensively known and very well-proven prior art, the construction in the field of cylinder-piston arrangement is significantly different than before.

Fig. 2 combined with Fig. 3 and Fig. 4 makes it clear that initially a cylinder 26 surrounding, upwardly beyond the cylinder 26 also extending, supporting frame 30 is provided. This frame 30 is at the bottom firmly connected to the valve block 10 in an axially precisely determined position, but in principle detachable from the valve block 10. The solubility of the frame 30 from the valve block 10 is here realized by the fact that at the top of the valve block 10, an external thread is provided and that the frame 30 has a flange below, which is provided with a cap 31 with internal thread.

The larger illustration in the Fig. 3 and 4 makes it clear that the cap 31 is guided on the frame 30 and can escape upwards. The frame 30 can thus be brought first with its lower edge in the desired position on the valve block 10. Therein, while retaining this position, the cap 31 can be screwed onto the external thread on the valve block 10 and the frame 30 can thus be fixed relative to the valve block 10.

In principle, it would also be possible to connect the frame 30 inseparably fixed to the valve block 10 or even to carry it in one piece, as has been indicated in the cited prior art for the jacket of the cylinder. For reasons of cleaning, sterilization and repair of such a bottle top device, it is advantageous to provide a firm, but in principle releasable connection of the frame 30 with the valve block 10.

It is also essential for the frame 30 that it also receives or carries the piston drive 29. This means that although the piston drive 29 does not have to be part of the frame 30, in any case the frame 30 represents the supporting component for the piston drive 29 and determines its position relative to the valve block 10. In the illustrated preferred embodiment, the frame 30 is expanded and extended block-like upwards there and has there various recesses for receiving various parts of the piston drive 29. This will be discussed later.

As has already been indicated above, finally, a releasably connected to the valve block 10 outer housing 2 is provided. This encloses the frame 30 on the outside, thus forming the outer shell of the bottle top unit and protects the internal components. It extends beyond the piston drive 29 on the frame 30 in any case slightly upwards and is closed in the illustrated and preferred embodiment above.

The illustrated and preferred embodiment can in Fig. 2 in conjunction with the Fig. 3 and 4 Furthermore, recognize that the cap 31 can not be operated easily here. Rather, it is provided for safety reasons and for reasons of accessibility in the outer housing 2, that the cap 31 can be operated only with a special tool 32. This tool 32 can be seen in Fig. 2 top left in a suspension at the back of the outer housing 2.

In the Fig. 3 and 4 Particularly well to be recognized dimensional ratios can be seen that the illustrated and preferred embodiment further, regardless of what has been stated above, characterized in that the stroke quotient, ie the ratio of maximum stroke of the piston 27 to effective diameter of the piston 27, between 1 and 3, preferably between 1.3 and 2.2. The importance of these proportions, and in particular a smaller stroke of the piston 27 of about 50 mm compared to the known from the prior art strokes of about 100 mm has been explained in detail in the general part of the description.

The small stroke of the piston 27 in the bottle top unit facilitates the closed design of the outer housing 2, because the complete stroke of the piston rod 28 can be handled within the outer housing 2. The outer housing 2 still does not have to be made excessively high. Also, it does not have to ride along with the piston rod 28 in whole or in part.

The illustrated construction thus increases the operating safety of the bottle top unit. The lower the bottle top unit, the higher the stability of a stock bottle 1 equipped with such a bottle top unit. The stroke quotient has a value of just under 2.0 in the illustrated embodiment for the nominal volume of 25 ml and a value of approximately 50 ml for the nominal volume 1.4. With a nominal volume of 100 ml, which would represent a rather unusually large arrangement, one would come to a value of about 1.0, which would mean an effective diameter of the piston 27 of about 50 mm.

The execution of the cylinder 26 as a calibrated glass tube with extremely high precision further increases the accuracy of the bottle top unit in total. The use of a calibrated glass tube as a cylinder 26 is useful and expedient here because of the measures taken otherwise.

The upper part of the frame 30 above the cylinder 26 lends itself as a guide for the upwardly and downwardly moving piston rod 28 in the radial direction. Fig. 3 and 4 show, moreover, that in the upper part of the frame 30, a drive shaft 33 of the piston drive 29 is mounted.

For the displacement of the piston rod 28 upwards and downwards offer various possibilities. Providing an immediate measurement on the piston rod 28 would not cause slippage between the drive shaft 33 and the piston rod 28, so even a friction gear could be used. Alternatives are a spindle drive o. The like. The illustrated and preferred embodiment uses the functional and proven technology of a gear drive back. For this purpose, it is provided here that the piston rod 28, preferably on the rear side, has an axially extending row of teeth 34 and the drive shaft 33 carries a pinion 35 which meshes with the row of teeth 34 or is coupled to it by a gear. Fig. 3 combined with Fig. 4 makes it clear that here in fact a reduction gear is provided with an intermediate shaft 36 and a further gear 37th

In order to engage as accurately as possible axially on the piston rod 28 and to initiate forces on the outer housing 2 as centrally as possible, it is provided in the illustrated and preferred embodiment that the pinion 35 and the drive shaft 33 arranged on the back of the piston rod 28, near the central longitudinal axis of the frame 30 are. With this arrangement, no additional torques arise on the piston rod, except for the transverse forces caused by the locally arranged gear drive. Consequently, the influence on the later-described measured value detection of the piston stroke is limited. This leads to a further increased operating safety and also to a comfortable operation of the piston drive 29.

Basically, you could interpret the piston drive 29 motor. For this one would have to integrate an electric drive motor in the outer housing 2. This is associated with considerable costs and leads to a much more expensive bottle attachment. The primary objective of the invention is a manually actuated bottle attachment device with an electronic, in particular digital measured value acquisition and display. In that regard show Fig. 1 . 3 and 4 in that the piston actuator 29 is designed for manual actuation and the drive shaft 33 at one end or at each end outside the outer housing 2 a manual operation knob 38 carries. It can be seen the two hand control knobs 38 left and right on the outer housing 2 in Fig. 1 ,

Overall, the geared connection between the drive shaft 33 and the pinion 35 is preferably designed so that a rotation of the manual operation knob 38 causes a downward movement of the piston 27 forward and downward. Ergonomic studies have shown that good dosing accuracy can be optimally associated with quickly picking up or dispensing large quantities of fluid when the maximum stroke of the piston 27 equals five to ten of the manual operation knob 38.

For the desired accuracy of the bottle cap device, which, as has been explained in the general part of the description, is considerably better than in all known from the prior art bottle cap devices, the design of the piston 27 in the cylinder 26 is important. For reasons of rigidity, it can be provided that the piston 27 is made in one piece with the piston rod 28, or designed as a separate part and firmly attached to the piston rod 28, in particular screwed.

The illustrated embodiment shows the piston rod 28, and screwed thereto by means of a central fastening screw 39, the piston 27, which here carries him a bottom side and circumferentially comprehensive slide piece 40 made of a very good sliding material, in particular PTFE.

The sliding piece 40 forms a cylinder 26 under pressure applied to the sliding ring 40a, which is deposited to generate pressure with a piston 27 supported on the spring ring 42 from a preferably also resistant to chemicals material. The spring ring 42 is shown in the drawing as Hlohlkammerring, for example made of chemical-resistant elastomer material. It is essential that the sliding ring 40 a itself does not have to apply the force to achieve the sealing effect of the sliding piece 40 on the inner surface of the cylinder 26. This is taken over by the spring ring 42, which is adapted for it. Incidentally, it can scarcely be recognized in the drawing that the outer circumferential surface of the sliding ring 40a can still be structured in order to realize, for example, a multi-start scraper ring.

For the achievable with the bottle attachment device accuracy is also advantageous that, as provided in the illustrated embodiment, the piston 27 is not down against the valve block 10, but the piston rod 28 or the piston 27 is driven up against a stop 43. You can see the stop 43 in Fig. 4 , It cooperates with a counterpart 43 'on the piston rod 28. The stop 43 can be adjustable and should be removable in any case in order to be able to pull out the piston 27 together with the piston rod 28, for example for cleaning or sterilization measures. This measure makes it possible, even in the lowest position of the piston 27, to leave a small gap to the valve block 10 or to the bottom of the cylinder 26. Bumps here can not bother you then. Of particular advantage is the arrangement shown, in which the stop 43 engages near the piston drive 29 on the piston 27 fixedly connected to the piston rod 28. As a result, the stop 43 and the point of force application of the piston drive 29 on the piston rod 28 are close to each other.

It has already been pointed out that it is particularly expedient if the outer housing 2 can be closed upwards. This is possible if the arrangement is such that the piston rod 28 is located completely within the outer housing 2 even when the piston 27 is in the highest position in the cylinder 26.

For a high accuracy of work with the bottle attachment device, it is advantageous if one can detect the inclusion of air bubbles in the liquid in the cylinder 26. In the event that the frame 30 is not designed as an open frame, but as a substantially closed housing, which is the case in the present embodiment (see in particular Fig. 2 and Fig. 4 ), it is recommended that the frame 30 in any case with a front view section 44 or a corresponding window and, as provided here ( Fig. 5 ), to provide a rear sight 45 or a corresponding window. This allows you to look into the cylinder 26 from the front or the back.

However, since we have an outer casing 2 here, a viewing cutout or a window in the frame would not be of any use if the outer casing 2 were not covered by the viewing cutout 44; 45 or window of the frame 30 would have a corresponding window 46 and 47, respectively. Such a viewing window may optionally be UV-protective colored, for example in brown color. The front window 46 in the outer housing 2 is also in Fig. 1 to recognize.

It has already been pointed out in the general part of the description that bottle top devices of the type in question are frequently also used with chemically aggressive liquids which develop corresponding vapors.

In particular, a wetting of the inner wall of the cylinder 26 in the amount of the piston rod 28 is unavoidable and leads to corresponding vapors. It is therefore of particular advantage to permanently ventilate the outer housing 2. For this purpose, ventilation openings 48, which expediently to achieve convection in the middle, z. B. concealed under the manual operation knob 38, or below near the valve block 10 and above the upper end of the outer housing 2 are arranged. The illustrated and preferred embodiment shows that the overhead ventilation openings 48 are arranged on the head of the outer housing 2, preferably under an actuating button 49 arranged on the upper side.

One recognizes in Fig. 1 on the top of the top of the outer housing 2, a large-area actuator button 49, which is labeled here with the word "Clear", that is, represents a zeroing button. Such is often used when working with a burette. The actuating button 49 on the top of the outer housing 2 is designed as a push button. Their operation is thus carried out by pressure from the top of the outer housing 2. Thus, a quick and error-free operation is possible without a serious tilting moment is exerted on the bottle top unit and the storage bottle 1 underneath. Unlike the arranged on the front of the outer housing 2 operation buttons 6 thus no holding back the outer housing 2 is required.

At the same time, the large-area actuating button 49 offers the possibility of hiding the ventilation opening 48 thereunder. This shows Fig. 2 ,

Already in connection with the explanation of the prior art has been pointed out that it would be appropriate for reasons of repair, cleaning and sterilization of the media-contacting parts of the Plaschenaufsatzgerätes to make the outer housing 2 openable. In the illustrated embodiment, it is provided that the outer housing 2 has a front housing shell 51 and a rear housing shell 52 detachably connected thereto. In the illustrated embodiment, see Fig. 2 and Fig. 5 , the front housing shell 51 is hooked behind the valve block 10 and firmly anchored in the middle (or top) of the frame 30. It is screwed there.

In the illustrated embodiment, the rear housing shell 52 is suspended at the top of the front housing shell 51. Below it is on the valve block 10 by means of the plug 24, which sits in the plug receptacle 23 and the bottle vent line 22 heard, fixed. Other fixation options are given, for example, here by a screw. Appropriately here is the simultaneous use of the plug 24, also because this is particularly well accessible from the back of the bottle top device. In Fig. 5 the rear housing shell 52 has been removed and accordingly also the plug 24 is missing.

The drawings, in particular Fig. 2 and Fig. 5 First, located in the outer housing 2, here in the front housing shell 51, more precisely attached to this, from the rear (as here), accessible from the front and / or from above, to the interior of the This receptacle 53 is used to hold electronic devices, in particular a populated circuit board 54. In the receptacle 53 is also the electronics of the display 4 including the display panel fifth

In the illustrated and preferred embodiment, in which the actuating button 49 is located on top of the outer housing 2, the receiving compartment 53 continues under the actuating button 49 angularly into the rear housing shell 52. As a result, the electronic devices under the operation button 49 can be protected in this receptacle 53. In particular, this is another board 55, which carries a pushbutton 56, which is actuated by the actuating button 49. This further board 55 is connected in the illustrated and preferred embodiment of the circuit board 54 via a film hinge 57 and sits even in a slot 58 of the receiving compartment 53. The film hinge 57 is formed in the illustrated and preferred embodiment of a circuit film web.

The receptacle 53 could be completed to the front by a possibly also the display 4 and the operation buttons 6 carrying compartment cover 59. Then, the receptacle 53 could be equipped with removed compartment cover 59 from the outside.

In all cases, the entire area is sealed off against vapors inside, so that the sensitive electronics are well protected even when working with aggressive chemical media.

It can be seen on the receiving tray 53 in the rest in the upper, extending to the rear housing shell 52 in area Fig. 2 and Fig. 5 another external Terminal 60. This is sealed to the rear housing shell 52. The port 60 represents an external interface of the electronic devices that can be used in any conventional manner.

While in the presentation in Fig. 2 the ventilation opening 48 below the actuating button 49 of the ventilation of the receiving compartment 53 are in Fig. 5 indicated, laterally below the actuating button 49 lying ventilation openings for the ventilation of the interior of the outer housing 2 in the rest responsible. One recognizes in Fig. 5 in this context, that the receiving tray 53 is at least in the rearwardly extending portion narrower than the outer casing 2 and is arranged centrally.

Furthermore one recognizes in Fig. 5 combined with Fig. 2 in that two battery compartments 61, namely right and left of the receiving compartment 53, are arranged in the outer housing 2, and here also in the front housing shell 51, that is, attached thereto. Each battery compartment 61 is closed by a cover 62 to the interior of the outer housing 2 in the rest. The lid 62 is in Fig. 2 recognizable, he has a handling tab 63. In Fig. 5 recognizes the battery compartments 61 without the lid 62 and without batteries. Of course, the battery compartments 61 are sealed by the lid 62 against the vapors occurring in the outer housing 2.

In principle, it would be possible to make the battery compartments 61 accessible from the front side.

The two in Fig. 5 recognizable battery compartments 61 leave between them a free space in which the piston rod 28 can go up. Accordingly, the wall of the receiving compartment 53 has a corresponding course here, which gives the piston rod 28 the necessary clearance.

The openable design of the outer housing 2 with the substantially fixed front housing shell 51 and the easily removable rear housing shell 52 is a simple way for the user to disassemble the cylinder-piston assembly, the piston 27 together with the piston rod 28 on the one hand and the cylinder 26 on the other hand to clean and also to change the piston 27 or the slide 40 if necessary.

Based on Fig. 3 Now further features of the measured value acquisition will be explained.

In the illustrated preferred embodiment, it is provided that the piston rod 28, preferably on the opposite side of the tooth row 34 carries an axially extending on the piston rod 28 gauge 64 and that adjacent to the piston rod 28, preferably in the upper part of the frame 30, a Sensor arrangement 65 is arranged with a sensor 66 aligned on the measuring strip 64. Here, therefore, a direct measured value recording on the piston rod 28 is provided, as it is basically known from the above-described prior art. Play in translation devices, as occurs in electromechanical data acquisition is systematically excluded here. This is particularly useful here if the other measures for stiffening the mechanical arrangement and increasing the accuracy are also taken.

The illustrated embodiment shows that the measuring strip 64 is aligned here on one side form-fitting manner on the piston rod 28. For this purpose, it is provided that the measuring strip 64 is inserted with a one-sided axial stop 67 in a pocket on the piston rod 28 and potted with a preferably chemical-resistant potting compound 68. One recognizes the potting compound 68 on the one hand at the bottom of the stop 67 in a small amount, on the other hand, top of the upper end of the piston rod 28. A potting compound 68 is easier to perform chemical resistant than normal glue. It also has a sufficient inherent elasticity to accommodate the minimum displacements of the measuring strip 64 relative to the piston rod 28.

In principle, measuring strips 64 made of plastic and offset with magnetic powder can be used.

The above-described minimum displacements of the measuring strip 64 relative to the piston rod 28 result from changes in the length of the piston rod 28 as well as from the different thermal expansion of the piston rod 28 and the measuring strips 64.

In Fig. 12 the assembly with piston 27, piston rod 28 and measuring strip 64 is shown. Contrary to the execution after Fig. 2 the measuring strip 64 as in the embodiment according to Fig. 11a / 11b in the piston rod 28 near the central axis of the piston 27 is arranged. The gauge 64 also does not become as in the embodiment Fig. 2 held. In this embodiment, the measuring strip 64 sits vertically near the piston 27 on the stop 67. The upper opposite end of the measuring strip 64 is displaced by a spring element 28 a vertically downward on the stop 67. Both contact surfaces are inclined, so that the measuring strip 64 is held in the direction of its lateral abutment against the piston rod 28.

In the execution after Fig. 12 the measuring strip 64 is not connected over its vertical length with the piston rod 28.

The execution after Fig. 12 keeps flexible the measuring strip 64 on the piston rod 28 by the spring element 28a. Temperature changes and different elongations have no influence on the attachment. In addition, the assembly of the measuring strip 64 without aids and / or a curing time is positive with respect to costs for production and repair.

In the illustrated embodiment, the spring element 28a and the piston rod 28 are made in one piece. The spring element 28a could also be a separate component, which is fastened to the piston rod 28 and consists of another material with good elastic properties. Likewise, the spring element 28a could be designed so that it holds the measuring strip 64 in the direction of its lateral abutment against the piston rod 28 in a form-fitting manner, for example by means of a molded-on bracket.

The structural details of a bottle top unit described so far are not fixed to the measuring principle of the displacement measuring system. According to a preferred teaching, which is also shown in the drawings so far, is working with a magnetic field-sensitive measuring system. For the different teachings of the present invention, however, optoelectronic and capacitive measuring systems may also be used.

Specifically, it is provided here that the displacement measuring strip 64 (measuring strip 64) is magnetized in sections spaced apart or partially magnetized in opposite directions, with a pitch of between 0.3 mm and 2.0 mm, preferably and as a compromise between resolution and cost approximately 1 , 0 mm.

The exemplary embodiment shown and in this respect shows a particularly expedient embodiment of a non-optical, in particular a magnetic field-sensitive sensor arrangement 65. This is located in one of the measuring strip 64 or to the interior of the outer housing 2 towards completely closed receiving pocket 69. This is used in the illustrated embodiment in the frame 30, namely screwed to this with slot connections 70. The slot connections 70 allow the exact alignment of the receiving pocket 69 on the measuring strip 64. In the illustrated and preferred embodiment, it is provided that the sensor 66 of the sensor arrangement 65 is arranged in the receiving pocket 69 on its side facing the measuring strip 64 behind a thin-walled wall portion 71. The purpose of the arrangement is to bring the sensor 66 as close as possible to the measuring strip 64, without actually touching it, and while maintaining a gas-tight seal of the sensor arrangement: 65 to the interior of the outer housing 2 out.

Details of the sensor arrangement 65 with the sensor 66 in the receiving pocket 69 are shown in FIG Fig. 6, 7 and 8th shown.

At first one recognizes in 6 and 7 in that the sensor 66 of the sensor arrangement 65 is seated on a board 74 inserted in the receiving pocket 69 in a slide-in guide 73, namely at the front edge thereof Fig. 3 and Fig. 6 on the left immediately adjacent to the thin wall portion 71. The wall section 71 here has, for example, only a thickness of about 0.1 to 0.2 mm. If the pitch of the measuring strip 64 is selected to be larger, the distance between the sensor 66 and the measuring strip 64 can also be greater. Then easier to produce, in particular injection-moldable wall sections can be designed, which will regularly have a slightly larger wall thickness of about 0.5 mm.

The receiving pocket 69 consists here of a total of a chemical-resistant and pourable temperature-stable plastic material, in particular PEEK. Length and width of the receiving pocket 69 are about 20 mm, the thickness of about 8 to 10 mm.

The wall portion 71 of the receiving pocket 69 can not be made in one piece with the receiving pocket 69, but separately. It would then be attached to the receiving pocket 69. For this purpose, the receiving pocket 69 may have an opening in the region of the wall section 71. A gas-tight film can be welded onto such an opening or otherwise fixed with the aid of and without auxiliaries, the opening on the receiving pocket 69. Such a gas-tight film usually has a thickness of about 10 microns to about 500 microns. These Foil now forms the wall section 71, which separates the sensor 66 from the measuring strip 64 in a gastight manner. In this way one can come to a very small distance of 0.1 mm or less.
The sensor arrangement 65 also has on the board 74 the evaluation circuit 72 for evaluating the output signals of the sensor 66 and for controlling the display 4. In principle, it is possible to construct the evaluation circuit 72 as a system solution with individual or multiple discrete components. A space-saving, energy-saving and cost-effective evaluation circuit 72 is achieved with the use of a mixed-signal controller, which evaluates the converted analog sensor signals directly via an interpolation software. However, the evaluation circuit 72 can also be realized with a software solution that is pure in the extreme case by means of a microprocessor or microcomputer, without leaving the meaning of the teaching.

Fig. 7 shows a perspective view of the receiving pocket 69 with inserted board 74 obliquely from behind. Here the board 74 is not yet shed. Likewise, the soldered to the board 74 and not shown with molded interface cable. It can be provided to completely shed the board 74 in the receiving pocket 69, and indeed with a chemical-resistant potting compound.
Interestingly, the completely separate, block-like design of the sensor assembly 65 in the receiving pocket 69 as a self-contained assembly of a device of the type in question.

Fig. 8 shows an arrangement of a particularly useful sensor 66 for a sensor assembly 65 of a device. Here it is provided that the sensor 66 is designed as a magnetoresistive sensor system based on the AMR effect. For details of this operating principle may be on the publication of Dr. Erik Lins, SENSITEC GmbH "Magnetoresistive with optical precision", dated August 1, 2005 s. This publication has been freely available on the Internet since August 2005.
Fig. 8 in short, shows two Wheatstone bridge circuits offset 45 ° from each other to produce a cosine signal (C) and a sine signal (S), taps at + C / -C and + S / -S. Operating voltage at Ub, against ground. The direction of magnetization of the measuring strip 64 is defined by H, the angle between H and the direction of current flow is indicated by β. By forming quotients of sine and cosine (arctangent function), the angle information becomes independent of the amplitude of the signals. As a result, on the one hand, the influence of the temperature is minimized, on the other hand, the working distance between sensor 66 and measuring strip 64 is not particularly critical. The separate evaluation of the sine and cosine signals provides some redundancy and, due to the fact that the sum of the squares is equal to 1, allows self-monitoring of the sensor 66 and offset amplitude correction, respectively.

In order to be able to carry out the above-described direct evaluation of the sinusoidal and cosinusoidal signals of the sensor 66 in order to achieve a good interpolation, a circuit arrangement 72 as described in US Pat Fig. 9 is shown as a block diagram. The sensor 66 is supplied with a clocked supply voltage 80, which is adjustable via an amplitude setting 81 on the sensor 66. The designated outputs (cos, sin) of the sensor 66 are connected to amplifiers 82, each with offset adjustment 82 '. After the amplifiers 82 there is a branch on the one hand to comparators 83 for comparison with a reference voltage 84, on the other hand to analog / digital converters 75 with downstream modules 85 and normalization stages 86. The assemblies 75, 85, 86, 87, 88 and 89 are in the present, so far preferred solution implemented in a mixed-signal controller. For more information on a mixed-signal controller, see the related notes and quotation point included in the general part of the description.

wird die tatsächliche Position des Kolbens 27 ermittelt und auf der Anzeige 4 zur Anzeige gebracht. Parallel dazu erfolgt eine Offset-Amplituden-Korrektur in einer Korrekturstufe 89 nach der Formel $${\mathrm{Dsin}}^2\mathrm{\beta }+{\mathrm{Dcos}}^2\mathrm{\beta =}\mathrm{A}{\prime }^2.$$

In the first branch with the comparators 83 there is a quadrant recognition in the stage 87. All signals are then supplied to the interpolation stage 88, in which an ARCTAN table is stored. After the formula $$\arctan \left(\frac{D\sin \beta }{D\cos \beta }\right)$$

the actual position of the piston 27 is determined and displayed on the display 4. In parallel, an offset amplitude correction takes place in a correction stage 89 according to the formula $${\mathrm{D\; sin}}^{}$$$${}^2\mathrm{\beta }+{\mathrm{<figure-callout\; id="2"\; label="D\; cos"\; filenames="imgf0001.png"\; state="\{\{state\}\}">D\; cos</figure-callout>}}^2\mathrm{\beta \; =}\mathrm{A}{\text{'}}^2,$$

With regard to the power consumption of the measuring system, a magnetoresistive measuring system is already quite expedient anyway, at least much cheaper than an optoelectronic measuring system. According to a preferred teaching, it is further provided here that the evaluation by means of the interpotation software takes place with an ON / OFF duty cycle of approximately 0.1 to approximately 0.02, preferably between approximately 0.05 and approximately 0.03, in particular with an ON / OFF duty cycle. Time from about 0.6 ms to about 0.1 ms, in particular between about 0.3 ms and about 0.15 ms. It is particularly recommended that the interpolation software with an interpolation between 200 and 1,000, in particular between about 400 and about 600, preferably from about 500 works.

One recognizes this keying in the schematic representation in Fig. 10 , One recognizes the course of the sine curve scanned here. There, an ON-time of 200 μs is shown as a time for the measured value acquisition by vertical blackened lines. In the gaps between the bars, the OFF time is 5.6 ms each. The duty cycle is thus about 0.036 in this embodiment.

Compared to the interpolation ICs known from the prior art, if one realizes the intended interpolation with an interpolation rate of about 500, one can reduce the power consumption to about 130 to 160 μA during operation. Mixed-signal controllers often have the option of selecting different power-saving modes in which different components or connections of the controller are de-energized or switched to trickle current. For example, the mixed-signal controller exemplified in the introduction to the description has five different power-saving modes (page 6 of the local data sheet), all of which are characterized in that the central computer unit (CPU) is switched off. In general, such a mixed-signal controller with different power saving modes is preferable because it can be optimally adapted to the specifics of a device according to the invention.

Here it has been assumed that with a manually operated device of the type in question, the adjustment speed of the piston 27 will not be greater than about 50 mm / s. Then the interpolation rate is tuned. This gives a resolution of the measuring path of about 2 μm and an accuracy of the measured value over the full measuring range of about 10 μm, the whole in a temperature range of + 10 ° C to about + 40 ° C.

An interesting construction is based on the embodiment of Fig. 11 (Fig. 11a, Fig. 11b ) explained. In the illustrated and preferred embodiment this construction applies to a magnetic field-sensitive sensor system, in particular a magnetoresistive sensor system.
Fig. 11a shows a precise alignment of the piston rod 28 on a side guide 90. It is provided here that on the same side on which the sensor assembly 65 is located, a side guide 90 is provided for the piston rod 28 and the sensor 26 is close to, preferably approximately at the level of Side guide 90 is arranged. This ensures that in the set position of the piston rod 28 in contact with the side guide 90 and the sensor 66 is aligned relative to the positioned on the piston rod 28 measuring strips 64 exactly. The parallelism of the measuring strip 64 with the sensor 66 is optimal over the full displacement of the piston rod 28.
Fig. 11b shows in conjunction with Fig. 11a in that a measurement error with regard to the distance measurement in the axial direction could also result from an inclination of the piston rod 28 in the cylinder 26, in particular relative to the piston 27. This measurement error occurs in a device of the type in question because of the otherwise achieved high precision. It is caused by the fact that the piston rod 28 in the region of the piston drive 29 has a certain lateral play, for example of 0.3 mm. This leads to a minimum, but disturbing in the context of the present measurement accuracy inclination of the piston rod 28, which causes a Wegmessfehler.
In the case of an optical measurement, it is now advisable to make this error as small as possible by the measuring strip 64 on the piston rod 28 on the one hand and the sensor assembly 65 are arranged with the sensor 66 on the other hand so that when located in the target position piston rod 28 the the sensor 66 facing surface of the measuring strip 64 forms a plane which lies on the longitudinal central axis of the piston rod 28. This arrangement rule for the measuring strip 64 on the piston rod 28 is based on the recognition that in a Auflichtsystem the surface of the measuring strip 64 is the interface between the measuring strip 64 and sensor 66. If I place these as close as possible to the longitudinal central axis of the piston rod 28, I minimize the measurement error resulting from the play-related inclination of the piston rod 28.

In contrast, in the case of the magnetoresistive measuring system according to the invention, the sensor 66, which detects the magnetic field of the measuring strip 64, lies on the longitudinal central axis of the piston rod 28. This is in Fig. 11a, b shown. The The interface in the magnetoresistive measuring system is the sensor 66, which is penetrated by the field lines of the periodically magnetized measuring strip 64. Tilts the measuring strip 64 as in Fig. 11b Although the output field of the field lines moves slightly to the left, the tilting causes the direction of the field lines to also be tilted; these run slightly upward from the measuring strip 64 in the direction of the sensor 66. At the interface, namely at the sensor 66, slightly changes only the amplitude, which is correctable, but not the phase position, which is crucial for the distance measurement.

For a capacitive sensor system with a corresponding measurement strip 64, the interface is somewhere between the two previously described orientations.

The previously explained small distance of the various interfaces to the longitudinal central axis of the piston rod 28, which is still tolerable for the measuring system, of course, depends on the required resolution of the measuring system. In addition, the stroke quotient also indirectly influences the still tolerable minimized distance. With a small stroke quotient, the distance between the movement range of the piston 27 and the side guide 90 for the piston rod 28 is generally also smaller. Thus, the game-related inclination of the piston rod 28 is greater. The shorter the distance between the bearing of the piston and the greater the clearance in these longitudinal guides, the closer the interface must be to the longitudinal central axis of the piston rod 28.

In the case of the relative position of measuring strips 64 and sensor 66 realized according to the teachings of the invention, the sensor 66 in the sensor arrangement 65 no longer lies next to the piston rod 28 but in its light profile. Accordingly, it is recommended that the piston rod 28 has a corresponding position of the sensor 66 permitting recess or flattening.

Fig. 12 shows a particularly interesting constructive solution for fixing the measuring strip 64 in the piston rod 28, taking into account the above-mentioned boundary conditions. This has already been explained above.

Basically, the above statements apply to the embodiment of Fig. 11a, b also for an eccentric arrangement of the piston rod 28. However, the design is of particular importance, in which the piston rod 28 is guided by the side guide 90 - in conjunction with the piston 27 in the cylinder 26 - with its longitudinal central axis on the longitudinal central axis of the cylinder 26.

The illustrated embodiments show; the sensor arrangement 65 is not arranged on the outer housing 2 but on the dimensionally stable frame 30. Thus, the entire metrological chain is completely concentrated on the frame 30, so that its dimensional stability leads to the excellent accuracy of the bottle-top device according to the invention.

As already explained above, it can be provided that the measuring strip 64 is an optical scale and the sensor arrangement 65 is a high-resolution incident-light system, in particular with four incident-light diodes. Then, the construction in the area of the sensor arrangement 65 is of course different from what has been described above.

With the measures implemented according to the invention, the accuracy of measurements in the bottle-top device according to the invention can be increased to an accuracy R of approximately +/- 0.06% and a coefficient of variation VK of approximately 0.02% at nominal volumes of 25 ml and 50 ml. These are values that otherwise can only be achieved by high-precision motorized bottle attachments. The high accuracy of the bottle attachment device according to the invention is also due to the fact that all mechanically moving parts are fixed axially and dimensionally stable with respect to the valve block 10. This, in conjunction with the direct data acquisition directly on the piston rod 28 makes a backlash in reversing the direction of actuation superfluous.

By special design measures the occurrence of tilting moments on the bottle top unit is systematically avoided or reduced to a minimum. In this context, the comparatively small height of the outer housing 2 is important, which is possible despite the fixed outer housing 2, because a comparatively small stroke of the piston 27 is realized.

Claims (15)

1. Bottle attachment for handling liquids with
   a cylinder-piston arrangement for precisely taking up and dispensing partial liquid volumes, with a cylinder (26) and a piston (27) running in a sealed-off manner in the cylinder (26) and having a piston rod (28) led upwards out of the cylinder (26),
   a displacement measuring strip (64) arranged directly on the piston rod (28) and extending axially in the direction of movement of the piston rod (28),
   a sensor arrangement (65) arranged fixed in place in the bottle attachment adjacent to the piston rod (28) and having a sensor (66) aligned with the measuring strip (64) and separated from the measuring strip (64) only by a narrow gap,
   an indicator (4) for the amount of liquid that is respectively handled or to be handled, and
   an electronic evaluation circuit (72) for evaluating output signals of the sensor (66) and, if appropriate, for activating the indicator (4),
   wherein the electronic evaluation circuit (72) can also be realized by the software of a microprocessor or microcomputer,
   characterized in
   that the sensor (66) in the sensor arrangement (65) lies in the clear profile of the piston rod (28) and that the piston rod (28) has a recess making it possible to have the corresponding position of the sensor (66) and

   - that the measuring strip (64) is an optical scale and the sensor arrangement (65) is a high-resolution reflected light system, wherein, on the one hand, the measuring strip (64) is arranged on the piston rod (28) and, on the other hand, the sensor arrangement (65) with the sensor (66) is arranged such that, when the piston rod (28) is in a desired position, a surface of the measuring strip (64) which faces the sensor (66) forms a plane which lies on a longitudinal mid-axis of the piston rod (28), or

   - that the measuring strip (64) is a plastic strip mixed with magnetic powder or, preferably, a ceramic strip and the sensor arrangement (65) is a high-resolution reflected light system, preferably a magneto resistive system, wherein the sensor (66) detecting a magnetic field of the measuring strip (64) lies on the longitudinal mid-axis of the piston rod (28), or

   - that the measuring strip (64) is a capacitive displacement measuring strip and the sensor arrangement (65) is a high-resolution capacitive measuring system, wherein, when the piston rod (28) is in a desired position, the longitudinal mix-axis of the sensor rod (28) lies between a surface of the measuring strip (64) which faces the sensor (66) and the sensor (66) itself.
2. Bottle attachment according to claim 1, characterized in that the piston rod (28) is guided with its longitudinal mid-axis on the longitudinal mid-axis of the cylinder (26) by means of a side guide (90) .
3. Bottle attachment according to claim 2, characterized in that the side guide (90) is arranged about level with the sensor (66).
4. Bottle attachment according to any one of claims 1 to 3, characterized in that the measuring strip (64) is placed in a pocket on the piston rod (28) and is cast at least on one of its circumferential surfaces with a preferably chemical-resistant casting compound (68) .
5. Bottle attachment according to claim 4, characterized in that the measuring strip (64) is placed with a one-sided axial stop (67) in the pocket on the piston rod (28), and that, preferably, the one-sided axial stop (67) in the pocket of the piston rod (28) is the surface facing the piston (27).
6. Bottle attachment according to one of claims 1 to 3, characterized in that the measuring strip (64) is placed in a pocket on the piston rod (28) and is flexibly held at its end facing away from the piston (27) or from the stop (67) by means of a spring element (28a) supported on the piston rod (28), while being subjected to force in the direction of the piston (27) or the stop (67) and/or in the direction of its lateral abutment with the piston rod (28), wherein, preferably, the spring element (28a) is formed in one piece on the piston rod (28).
7. Bottle attachment according to one of the preceding claims, wherein the measuring strip (64) is a plastic strip mixed with magnetic powder or, preferably, a ceramic strip, and the sensor arrangement (65) is a high-resolution magnetoresistive system sensitive to magnetic fields, wherein the sensor (66) detecting a magnetic field of the measuring strip (64) lies on the longitudinal mid-axis of the piston rod (28), characterized in that the spacing of the magnetic portions of the measuring strip (64) is between 0.3 mm and 2 mm, preferably 1 mm.
8. Bottle attachment according to any one of the preceding claims, wherein the measuring strip (64) is a plastic strip mixed with magnetic powder or,
   preferably, a ceramic strip, and the sensor arrangement (65) is a high-resolution magnetoresistive system sensitive to magnetic fields, preferably based on the AMR-effect, wherein the sensor (66) detecting a magnetic field of the measuring strip (64) lies on the longitudinal mid-axis of the piston rod (28), characterized in that the displacement measuring strip (64) is magnetized at spaced-apart portions, or, preferably, is magnetized contradirectionally in portions,
   that the evaluation circuit (72) has a mixed-signal controller, with which the converted analog sensor signals can be directly evaluated using interpolation software,
   wherein, preferably, the mixed-signal controller replaces a three-stage arrangement of an A/D-converter, a processing stage with processing software and an output stage.
9. Bottle attachment according to claim 8, characterized in that the mixed-signal controller is implemented as a PsoC, Programmable System on a Chip, as a DSP, Digital Signal Processor, or as an FPGA, Field Programmable Gate Array, the latter, if appropriate, with a preceding A/D converter.
10. Bottle attachment according to claims 8 or 9, characterized in that the evaluation can be carried out by means of the interpolation software with an ON/OFF duty factor of about 0.1 to about 0.02, preferably between about 0.05 and about 0.03, in particular with an ON time of about 0.6 ms to about 0.1 ms, in particular between about 0.3 ms and about 0.15 ms.
11. Bottle attachment according to any one of claims 8 to 10, characterized in that the interpolation software operates with an interpolation rate of between 200 and 1000, in particular between 400 and 600, preferably 500.
12. Bottle attachment according to one of the preceding claims and with a valve block (10), with a fastening arrangement (3) mounted or integrally formed on a bottom of the valve block (10), for fastening the valve block (10) on a storage bottle (1), with a cylinder receptacle (25), arranged on a top of the valve block (10), in which the cylinder (26) is arranged sealed off with respect to the valve block (10), and with a piston drive (29) arranged above the cylinder (26) and drive-connected to the piston rod (28),
    characterized in
    that a one-piece carrying frame (30) is provided, surrounding the cylinder (26) and extending upwards beyond the cylinder (26), the carrying frame (30) being connected to the valve block (10) and receiving the piston drive (29), wherein, preferably, the piston (27) is not movable downwards against the valve block (10) but is movable upwards against a stop (43), wherein there is a gap between the bottom of the piston (27) and the bottom of the cylinder (26), wherein, further preferably, the stop (43) is adjustable and/or removable and/or engages the piston rod (28) near the piston drive (29).
13. Bottle attachment according to one of the preceding claims and with a valve block (10),
    a fastening arrangement (3), mounted or integrally formed on the bottom of the valve block (10), for fastening the valve block (10) on a storage bottle (1), and
    with a cylinder receptacle (25) mounted on top of the valve block (10), in which the cylinder (26) is arranged sealed off with respect to the valve block (10), characterized in
    that a piston drive (29) drive-connected to the piston rod (28) and an outer housing (2) are provided, the outer housing (2) being mounted over the piston-cylinder-arrangement (26-28) and being closed at the top and being arranged fixedly on the valve block (10), that on the upper side of the outer housing (2) there is arranged at least one actuating button (49), which can be pressed downwards for actuation and which is in particular a zero-setting button or a resetting button, and/or
    that the outer housing (2) is provided with ventilation orifices (48), wherein to achieve convection, the ventilation orifices (48) are arranged centrally and/or at the bottom and/or on top of the outer housing (2), and/or,
    that the piston rod (28) is located completely inside the outer housing (2) even when the piston (27) is in a highest position in the cylinder (26).
14. Bottle attachment according to one of the preceding claims, characterized in that the sensor arrangement (65) is arranged in a receiving pocket (69) that is completely closed with respect to the measuring strip (64),
    wherein, preferably, the receiving pocket (69) is provided with long-hole connections (70) for the exact alignment of the receiving pocket (69) with the measuring strip (64).
15. Bottle attachment according to one of the preceding claims, characterized in
    that the stroke quotient, i.e. the ratio of the maximum stroke displacement of the piston (27) to the effective diameter of the piston (27), is between 1 and 3, preferably between 1.3 and 2.2,
    wherein, preferably, the maximum stroke displacement of the piston (27) is about 50 mm and the stroke quotient for a nominal volume of 25 ml is about 2.0 and for a nominal volume of 50 ml is about 1.4.

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