EP3508274B1 - Bottle attachment for handling fluids - Google Patents

Description

The invention relates to a bottle top device for handling liquids. These devices are about the precise measuring and delivery of liquids from a storage bottle or other storage container, with the precise measuring when taking up a partial volume of liquid from the storage bottle or the like into the device and/or when dispensing a partial volume of liquid from the device to the outside into a container.

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

In the present context, the term "liquid" refers to liquids such as those used extensively in chemistry, biology, pharmacy, etc. in the laboratory and in production, in particular liquids with a relative viscosity of up to around 300 (viscosity based on the viscosity of water under normal conditions ). This is the liquid range from very thin to slightly thick.

A manually operated burette is used during titration to determine the unknown amount of a dissolved substance from the consumption of a reagent liquid with a known concentration. In order to ensure practical and economical analysis work, a burette is required to quickly and accurately dispense and display the specific amount of liquid. High demands are placed on the precision of liquid dispensing as well as on operator safety (General Catalog 600 "Laboratory Equipment from Brand" of BRAND GMBH + CO KG 09/01, No. 9963 00, "Bürette Digital III", pp. 27 to 34).

Comparable requirements can also be found in bottle-top dispensers, especially those with a digital display of the desired dosing volume ( DE 35 16 596 A1 ; 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, i.e. in its position attached to a storage bottle and essentially vertically aligned.

There is usually a suction valve in the valve block, which allows liquid to be sucked in from the storage bottle using a suction pipe. An exhaust line with an exhaust valve located in it extends approximately horizontally from the valve block. Since the discharge line projects approximately horizontally from the valve block and often carries an additional switching valve, this is the side from which an operator works with the bottle top device. We will henceforth refer to this side as the “front” or “front”. The opposite side is the "back" or "back". A bottle top device usually has a display with appropriate controls at the front.

A well-known bottle attachment device for handling liquids (see the general catalog 600 "Burette Digital III", as stated above) is characterized by the fact that the cylinder-piston arrangement is covered from above by an outer housing that is closed at the top. This outer housing moves up together with the piston rod relative to the cylinder. To accomplish this, there is a vertical rack on the cylinder with which a pinion meshes on a drive shaft that is mounted in the outer housing. The piston drive of this bottle top device is designed for manual operation and therefore the drive shaft carries a manual operation knob at both ends outside the outer housing.

The advantage of this bottle-top device is that the outer housing is closed around the cylinder-piston arrangement. But this comes at the cost of moving the entire outer housing with all the components arranged within it. Particularly when the outer housing is in the fully raised position, such an arrangement of bottle top device and storage bottle has a considerable tendency to tip over.

Other bottle top devices also show a similar concept with a corresponding tilting tendency ( DE 35 16 596 A1 ; DE 35 34 550 A1 ).

Another solution can be found in a bottle-top device in the form of a piston burette with a digital display, in which a housing containing the piston drive, the display, a sensor arrangement and control electronics is in a fixed, unchangeable relative position to the valve block ( DE 35 01 909 C1 ). Here the outer housing is not closed, but the piston rod passes through the housing from bottom to top when the piston is in the lowest position in the cylinder. When the piston is raised, the piston rod moves out of the top of the housing. A bellows connected at the top prevents dirt and dust from entering the housing via the opening for the piston rod.

In the bottle top device explained above, the tendency to tip over is somewhat lower than in the bottle top device described above, since the outer housing does not shift overall relative to the valve block. But this comes at the price of the outer casing being open at the top.

All bottle top devices of the type in question have operating buttons on the front of the outer housing. Actuating the operating buttons requires the outer housing to be held against it, at least if you want to safely prevent the arrangement of the bottle top device and the storage bottle from tipping over. This is particularly important for storage bottles with a small volume.

Many influences of construction and handling are important for the accuracy of a bottle top device of the type in question. Under Another important thing is the stick-slip effect, i.e. overcoming the static friction of the piston in the cylinder in the transition to sliding friction during adjustment. Many design factors of the bottle top device come into play here. User-friendliness and operator safety are essential boundary conditions.

The previously explained design features of the known bottle top devices are relevant for user-friendliness and operator safety. For accuracy and operator safety, the boundary conditions under which bottle top devices of the type in question are often used must also be taken into account.

What all previously explained devices for the measuring handling of small amounts of liquid in the fields of chemistry, biology, pharmacy, etc. in the laboratory, testing and production have in common is that they have a cylinder-piston arrangement for the precise absorption and delivery of partial liquid volumes. A sealed piston runs in a cylinder, with a piston rod extending upwards out of the cylinder. The movement of the piston rod is used to precisely determine the path of the piston.

In the case of a direct measurement on the piston rod, there is a position measuring strip directly on the piston rod, which extends axially in the direction of the piston rod ( DE 35 01 909 C1 ). If a housing with the piston rod moves upwards relative to the cylinder, the position measuring strip is expediently positioned on the housing or on another component connected to the piston rod in a fixed relative position. However, it is also possible to provide the arrangement in exactly the opposite way, i.e. to assign the distance measuring strip to a stationary component if you then assign a corresponding sensor arrangement to the moving housing.

What all of the previously explained devices also have in common is that small and minute amounts of liquid must be precisely determined. Given the state of the art from the DE 35 01 909 C1 A high-precision measuring arrangement with distance measuring strips and sensor arrangement is already provided, in which the play of otherwise necessary reduction gears of a measuring system of classic technology is eliminated ( DE 101 06 463 A1 ). Due to the direct arrangement of the distance measuring strip in this piston burette on the piston rod and the direct reading there using the sensor of the sensor arrangement, a significant source of error is eliminated.

With this device it is initially proposed that the measuring strip is an optical scale and the sensor arrangement is an reflected light system. As an alternative, it is suggested that the measuring strip is part of a capacitive system, which also includes the sensor. Electrodes facing one another are arranged in such a way that two pairs of measuring capacitances are formed for measuring the relative movement between the measuring strip and the sensor.

The third variant proposed for this device is that the piston rod carries a magnetic strip. Adjacent to the piston rod, a reading head is provided in a stationary manner in the housing, which is aligned with the magnetic measuring strip and separated from it by a gap. An electronic control circuit is coupled to the reading head, which reads the measurement information on the magnetic measuring strip and feeds corresponding pulses into the control circuit. This converts the impulses and controls a digital display, which in turn shows the volume of liquid dispensed based on the relative movement between the piston and cylinder.

With the above-mentioned direct arrangement of the distance measuring strip on the piston rod, as shown in DE 35 01 909 C1 As described, the measuring strip is also moved into the cylinder. In this area, the inner wall of the cylinder is wetted with the liquid to be dosed. The interior is encapsulated by sealing measures, so that the sensor arrangement may also be intensively exposed to the resulting vapors.

If you use magnetized position measuring strips in sections, you can also realize an incremental position determination of a piston rod and thus of the piston in the cylinder.

For the evaluation and the corresponding software for 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 to 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 standardized for assignment to the interpolation table. This requires comparatively fast, power-intensive and relatively expensive analog/digital converters etc. ( DE 34 17 016 C1 ).

Since the number of sections of the distance measuring strip is limited for mechanical reasons (typically a section is about 1 mm long), a significantly higher resolution of the measured values can only be achieved by evaluating the analog sinusoidal (and cosinusoidal) signals directly, instead of just their zero crossings to use. You have a sinusoidal signal and a cosine-shaped signal because you normally work with two magnetic field-sensitive sensors that are offset with respect to the pitch of the distance measuring strip so that they emit two signals that are offset from each other by a quarter of a period.

For the devices described above for the measuring handling of small amounts of liquid, power consumption is an essential criterion, with the devices currently available on the market managing with one battery for several years (applicant's general catalog, loc. cit., page 31, "Burette Digital III").

Previously known sensor arrangements and their associated evaluation circuits have a current consumption of well over 5 mA to approximately 25 mA during operation at an interpolation rate between 200 and 1000. This requires essential more powerful batteries or accumulators than are common today, which would only last a few hours of operation in such a circuit.

The DE 35 34 550 A1 shows a precision dosing device for precisely dosing liquid media from a storage container into a template with a piston slide dosing pump. The well-known precision dosing device consists of a dosing cylinder made of glass, a dosing piston that can be closed in this and a valve head containing a suction valve and a drain valve, which holds the dosing cylinder and can be connected to the storage container, with a sleeve connected to the dosing piston and extending telescopically over the dosing cylinder and with a digital display device for the stroke volume and/or the differential stroke volume of the piston slide metering pump. In addition, a graduated measuring rod and a sensor that scans this measuring rod without contact are provided. The sensor generates signals that represent the metering piston stroke, which, after evaluation in an electronic evaluation circuit, are displayed on the digital display device. The measuring rod is stationary on the dosing cylinder and the sensor is stationary on the sleeve or vice versa. The sensor, the evaluation circuit and an LCD element as a digital display device can be combined with a power source in a modular manner in a single building block, whereby the components mentioned in this building block can be encapsulated in a hermetically and corrosion-resistant manner in order to protect the components from corrosive vapors. This building block is then arranged on the sleeve. Accordingly, the measuring rod is provided in a stationary manner on the dosing cylinder.

The teaching of the present invention is based on the problem that emerges from the document DE 35 34 550 A1 to improve the known precision dosing device with regard to distance measurement.

The previously identified problem is solved in the case of a bottle top device with the features of the preamble of claim 1 by the features of the characterizing part of claim 1.

The sensor arrangement can optionally be cast on the back of the receiving pocket with casting compound in order to ensure an optimal protective effect for the sensor arrangement. Of course, this only works with a matching measuring strip.

A non-optical sensor arrangement, in particular a sensor arrangement that is sensitive to magnetic fields, involves 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 suction, now only flows past the sensor arrangement protected by the receiving pocket. It can no longer occupy the sensor as condensate and impair its function.

A useful alternative has a wall section of the receiving pocket that is designed as a film. This film should be extremely thin and have low permeability to the gases that occur. Such a thin film can even be made of transparent material so that the sensor of the sensor arrangement can work optically.

According to a further, particularly preferred embodiment, it is provided that the sensor is arranged in the receiving pocket on the side facing the measuring strip behind a thin-layer wall section of the receiving pocket. The sensor has been brought as close as possible to the measuring strip without actually touching it, and while maintaining a gas-tight seal between the sensor arrangement and the interior of the device.

To improve the distance measurement and its evaluation, it can also be provided that the sensor is designed as a magnetoresistive sensor system, in particular based on the AMR effect, and that the evaluation circuit has a largely highly integrated, cost-effective mixed-signal controller, which converts the analog sensor signals evaluated directly via interpolation software.

Mixed-signal controllers are microcontrollers that combine various electronic processing functions, also suitable for evaluating sensor signals via interpolation software, with the functions of an A/D converter. A mixed-signal microcontroller thus replaces a three-stage arrangement consisting of an A/D converter, a processing stage with processing software and an output stage. Such a mixed-signal microcontroller is generally much more cost-effective to use at the signal level of AMR sensors than a three-stage arrangement. Microcontrollers are offered by different providers with different performance spectrums (see e.g. B. the data sheet "MSP 430 x 33 x MIXED SIGNAL MICROCONTROLLER", February 1998, Texas Instruments ). A mixed-signal microcontroller not only creates a simple solution for signal processing, but also very low power consumption both during operation and in idle state. (For detailed information, please refer to the relevant data sheets, in particular the data sheet mentioned above.)

Mixed-signal controllers can be implemented 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 converter, so that a discrete upstream A/D converter turns the entire arrangement into a mixed-signal controller of the type described.

It is particularly advantageous if the evaluation is carried out using the evaluation circuit with an ON/OFF duty cycle of approximately 0.1 to approximately 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. Furthermore, it appears particularly advantageous that the interpolation software works with an interpolation rate between 200 and 1,000, in particular between approximately 400 and approximately 600, preferably approximately 500.

By using a corresponding duty cycle, it is possible to reduce the power consumption of the measuring system according to the invention to less than a tenth of the power consumption of the interpolation ICs of the prior art, namely to less than 200 µA during operation.

Overall, with the measures explained above, the measuring system based on magnetic field measurement can be significantly optimized in a device of the type in question.

With 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 manufacturing costs are also lower than with classic bottle top devices.

With a very high resolution of the measured value acquisition, which can be achieved, for example, due to a particularly practical mechanical design of a device of the type in question, effects that have so far remained unconsidered have an influence on the measurement results. What is particularly important is the play of the piston rod in the piston drive. The lateral play in the piston drive allows the piston rod to tilt laterally relative to the piston, which can distort the measurement result at high resolution.

As has already been mentioned, it is advantageous to make the bottle top device largely chemical-resistant. However, it's not just about the surfaces that come into contact with the liquid. Surrendered indeed Corrosive or otherwise damaging liquids also produce corresponding vapors, which can cause problems in the interior of the outer housing of the bottle top device.

In the case of the above-mentioned bottle top device with a bellows, it is particularly problematic that the vapors emanating from the wetting of the inner wall of the cylinder cannot escape. The space surrounding the piston rod is displaced by the piston during the suction process. This atmosphere escapes past the sensor system and occupies it. The permanent exposure of these vapors to such components in a closed and unactuated housing quickly leads to significant malfunctions.

In order to achieve a particularly high level of user-friendliness and operator safety, at least one actuation button can be relocated from the display on the front of the outer housing to its top side. Depending on the space and requirements, two or even more actuation buttons can be arranged on the top of the outer housing.

As required, the outer housing is closed on the top and includes the cylinder-piston arrangement from above. The solution takes advantage of this fact, which has been known for decades, to optimize the possibility of operating the bottle top device. An operating button, which is often used when working with the bottle top device, can be activated here by pressing it from above. This enables quick and error-free operation without exerting a serious tilting moment on the bottle top device and the storage bottle underneath. In contrast to the operating buttons arranged on the front of the outer housing, no counter-holding of the outer housing is required.

The solutions, which increase operator safety in particular, can in principle be used in both types of bottle top devices discussed above, i.e. with a moving outer housing and with an outer housing that is fixed to the valve block. The term “fixed” in this context means that in this variant the outer housing is not moved relative to the valve block when the piston of the cylinder-piston arrangement is moved. However, this outer housing can be detachable from the valve block in order to carry out repairs or cleaning or sterilization of the cylinder and/or the piston or other assemblies.

No liquid is released when the outer housing is pressed from above. On the one hand, the outer housing does not move when a force acting vertically from above is applied to it. On the other hand, no protruding piston rod can be driven.

In principle, the previously explained measures can be advantageously implemented in a bottle top device with a motor drive of the piston. There, the tendency to tip over is usually lower than with a manually operated bottle top device. Therefore, both variants are particularly advantageous in a bottle top device designed for manual operation.

Finally, the present bottle attachment device is particularly preferably a burette, i.e. designed as a burette.

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 der 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 erfindungsgemäßen Messsystem eingesetzt werden kann,

Fig. 9

eine Auswerteschaltung für einen solchen AMR-Sensor,

Fig. 10

ein Diagramm, das die Tastung bei dem bevorzugten erfindungsgemäßen 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 invention will now be explained in more detail below with reference to a drawing which only shows particularly preferred and non-restrictive exemplary embodiments. Shown in the drawing

Fig. 1

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

Fig. 2

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

Fig. 3

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

Fig. 4

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

Fig. 5

the bottle top device Fig. 1 Seen from behind, the rear housing shell has been removed and the battery compartment covers have also been removed,

Fig. 6

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

Fig. 7

the receiving pocket with the sensor arrangement located therein in a perspective view diagonally from behind,

Fig. 8

a schematic diagram of an AMR sensor, which can be used as a magnetoresistive sensor in the measuring system according to the invention,

Fig. 9

an evaluation circuit for such an AMR sensor,

Fig. 10

a diagram that shows an example of the keying in the preferred measuring system according to the invention,

Fig. 11a

a preferred embodiment of a cylinder-piston arrangement with a measured value acquisition according to the invention for a magnetoresistive measurement with the piston rod in the desired position,

Fig. 11b

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

Fig. 12

in an enlarged view in Fig. 3 A piston with a piston rod with a measuring strip in a particularly practical arrangement in a similar orientation.

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

In general, for bottle-top devices for handling liquids, so-called "liquid handling devices", reference may be made to the applicant's general catalog "600 General Catalog - Laboratory Devices from BRAND" 09/01, pages 9 to 34. There, bottle-top dispensers and burettes are explained in terms of construction and application.

Examples of burettes as bottle-top devices have been given in the introduction ( DE 35 01 909C1 ; EP 0 096 088 B1 ; DE 101 06 463 A1 ; DE 35 16 596 A1 ). Bottle top dispensers, for example, result from the DE 88 00 844 U1 and especially that EP 0 542 241 A1 , which will be discussed further below.

The definitions of top and bottom as well as front and back that were given at the beginning of the description apply to the bottle top device, which is described below. The bottle top device is always in the in Fig. 1 shown position on a storage bottle, even if it is not shown in this position.

This in Fig. 1 The bottle attachment device shown is located on a storage bottle 1 during operation. It has an outer housing 2 and is overall equipped with a fastening arrangement 3, here a cap, on a bottle neck Storage bottle 1 attached, screwed on here. At the top of the outer housing 2, facing forward, 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.

An ejection line 7 projects forward from the outer housing 2, which in the exemplary embodiment shown is arranged in an angular holder 8 and is closed at the end by means of a closure cap 9 for closure and as drip protection.

Details of the bottle top device according to the invention can now be seen from the sectional view in Fig. 2 .

The bottle attachment device shown initially has a valve block 10 in the outer housing 2. Attached to this or integrally formed is the already mentioned fastening arrangement 3, with which the valve block 10 is actually fastened to the storage bottle 1. At the same time, the outer housing 2 is then attached to the storage bottle 1.

The illustrated and preferred exemplary embodiment shows the valve block 10 as a component made in one piece from plastic, in particular from chemical-resistant plastic, which is provided with a large number of channels and internals. In detail, the construction largely corresponds to the valve block of the bottle top dispenser, which consists of the EP 0 542 241 A1 is known and is part of the state of the art.

The fastening arrangement 3 is designed as a cap that can rotate freely relative to the valve block 10. In a downwardly directed recess in the valve block 10 there is a suction valve insert 11, to which a suction line 12, which is shown shortened here for simplicity, connects downwards into the storage bottle 1. At the top, an intake channel 13 adjoins the intake valve insert 11 in the valve block 10, from which approximately half height an in Fig. 2 ejection channel 14 branches off to the right. An exhaust valve insert 15 is located in a recess in the valve block 10 on the discharge channel 14. Here, this is part of a valve body 16 of a changeover valve 17 attached to the valve block 10. On the outflow side, the changeover valve 17 is connected to the discharge line 7 in the holder 8. In the sectional view in Fig. 2 the holder 8 runs in an arc and guides the ejection line 7 in the same arc, so that the ejection opening points downwards. There it is closed with the closure cap 9.

The changeover valve 17 has in the valve body 16 a valve body 18 which can be rotated about a vertical axis of rotation and which also has an in Fig. 1 recognizable toggle 19 can be adjusted by hand. Below the exhaust valve insert 15, a return channel 20 runs in the valve body 16, which continues in the valve block 10 up to a downward return line 21.

At the in Fig. 2 illustrated and in Fig. 1 recognizable position of the toggle 19, the switching valve 17 is switched to passage, so that the discharge channel 14 is connected to the discharge line 7. However, in a position of the valve body 18 rotated by 90°, the ejection channel 14 is connected to the return channel 20, so that liquid is conveyed in the circuit from the storage bottle 1 and back into the storage bottle 1 via the return line 21. In detail, for the entire background of this so-called “redosing” please refer to the detailed explanations in the EP 0 542 241 A1 to get expelled.

The valve block 10 also contains a bottle ventilation line 22 near the rear, which opens into a rear-facing, radially open plug receptacle 23. In the stopper receptacle 23 there is a stopper 24 or a similar closure element that closes it, but which has a small passage opening, so that the interior of the storage bottle 1 is connected to the ambient atmosphere via the bottle ventilation line 22 and this passage in the stopper 24. This makes it possible to equalize the pressure in the storage bottle 1.

On the valve block 10, which is made here in one piece from chemical-resistant plastic material, for example PFA, a cylinder 26, which is preferably made of glass and is also made of glass, is firmly attached in a cylinder receptacle 25 and sealed against the valve block 10. Specifically, the cylinder 26 is pressed into the cylinder receptacle 25.

For information about various plastic materials and their abbreviations, reference is made to the relevant specialist literature and also to the applicant's general catalog mentioned above, here in particular pages 224, 225.

In the cylinder 26 there is a piston 27 running sealed therein with a piston rod 28 which is led upwards out of the cylinder 26. Above the cylinder 26 there is a piston drive 29 which is in drive connection with the piston rod 28. The display 4 for the handled or still closed The amount of liquid to be handled has already been mentioned above.

While in the area of the valve block 10 the bottle attachment device shown is designed in accordance with the already extensively known and very proven state of the art, the construction in the area of the cylinder-piston arrangement is significantly different than before.

Fig. 2 combined with Fig. 3 and Fig. 4 makes it clear that initially a supporting frame 30 is provided which surrounds the cylinder 26 and extends upwards beyond the cylinder 26. This frame 30 is firmly connected at the lower end to the valve block 10 in an axially precisely determined position, but is fundamentally detachable from the valve block 10. The detachability of the frame 30 from the valve block 10 is achieved here by the fact that an external thread is provided at the upper edge of the valve block 10 and that the frame 30 has a flange at the bottom which is provided with a cap 31 with an internal thread.

The larger representation in the Fig. 3 and 4 makes it clear that the cap 31 is guided on the frame 30 and can move upwards. The frame 30 can therefore first be brought into the desired position on the valve block 10 with its lower edge. Then you can screw the union cap 31 onto the external thread on the valve block 10 while maintaining this position and fix the frame 30 relative to the valve block 10.

In principle, it would also be possible to inseparably connect the frame 30 to the valve block 10 or even to make it in one piece, as was indicated in the prior art explained at the beginning for the jacket of the cylinder. However, for reasons of cleaning, sterilizing and repairing such a bottle top device, it is advantageous to provide a fixed but fundamentally detachable connection of the frame 30 to the valve block 10.

It is also essential for the frame 30 that it also accommodates or carries the piston drive 29. This means that the piston drive 29 does not have to be part of the frame 30, but 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 and preferred exemplary embodiment, the frame 30 is expanded or extended in a block-like manner towards the top and has various recesses there for receiving various parts of the piston drive 29. This will be discussed later.

As already indicated above, an outer housing 2 which is detachably connected to the valve block 10 is finally provided. This encloses the frame 30 on the outside, thus forming the outer shell of the bottle top device and protecting the internal components. In any case, it extends slightly upwards beyond the piston drive 29 on the frame 30 and is closed at the top in the illustrated and preferred exemplary embodiment.

The illustrated and preferred exemplary embodiment leaves in Fig. 2 in connection with the Fig. 3 and 4 also recognize that the cap 31 cannot be easily operated here. Rather, for safety reasons and for reasons of accessibility in the outer housing 2, it is provided that the cap 31 can only be operated with a special tool 32. This tool 32 can be seen in Fig. 2 Top left in a suspension on the back of the outer housing 2.

In the Fig. 3 and 4 The particularly easy-to-recognize dimensional relationships show that the illustrated and preferred exemplary embodiment is further characterized, regardless of what has been previously stated, in that the stroke quotient, i.e. the ratio of the maximum stroke of the piston 27 to the effective diameter of the piston 27, between 1 and 3, preferably between 1.3 and 2.2. The significance of these dimensional relationships and in particular a smaller stroke of the piston 27 of approximately 50 mm compared to the stroke of approximately 100 mm known from the prior art has been explained in detail in the general part of the description.

The short stroke of the piston 27 in the bottle top device according to the invention facilitates the closed design of the outer housing 2 because the entire stroke of the piston rod 28 can be carried out within the outer housing 2. However, the outer housing 2 does not have to be made excessively high. It also does not have to travel completely or partially with the piston rod 28.

The construction according to the invention thus increases the operational safety of the bottle top device. The lower the bottle top device, the higher the stability of a storage bottle 1 equipped with such a bottle top device. In the exemplary embodiment shown, the stroke quotient has a value of just under 2.0 for the nominal volume of 25 ml and a value of approximately 2.0 for the nominal volume of 50 ml 1.4. With a nominal volume of 100 ml, which would represent a rather unusually large arrangement, you would get a value of about 1.0, which would mean an effective diameter of the piston 27 of about 50 mm.

The design of the cylinder 26 as a calibrated glass tube with extremely high precision further increases the overall accuracy of the bottle top device. The use of a calibrated glass tube as a cylinder 26 is sensible and effective here because of the other measures taken.

The upper part of the frame 30 above the cylinder 26 offers itself as a guide for the upward and downward moving piston rod 28 in a radial respect. Fig. 3 and 4 also show that a drive shaft 33 of the piston drive 29 is mounted in the upper part of the frame 30.

There are various options for moving the piston rod 28 upwards and downwards. If one provides for a direct measurement on the piston rod 28, there would be no slippage between the drive shaft 33 and the piston rod 28, so that even a friction gear could be used. Alternatives include a spindle drive or the like. The illustrated and preferred exemplary embodiment uses the practical and proven technology of a gear drive. For this purpose, it is provided here that the piston rod 28, preferably on the back, 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 geared to it. Fig. 3 combined with Fig. 4 makes it clear that a reduction gear is actually provided here with an intermediate shaft 36 and another gear 37.

In order to attack the piston rod 28 as accurately as possible axially and to introduce forces onto the outer housing 2 as centrally as possible, in the illustrated and preferred exemplary embodiment it is provided that the pinion 35 and the drive shaft 33 are arranged on the back of the piston rod 28, close to the central longitudinal axis of the frame 30 are. With this arrangement There are no additional torques on the piston rod, apart from the transverse forces caused by the locally arranged gear drive. Consequently, the influence on the measured value acquisition of the piston stroke, described later, is limited. This leads to further increased operational safety and also to convenient actuation of the piston drive 29.

In principle, the piston drive 29 could be designed as a motor. To do this, an electric drive motor would have to be integrated into the outer housing 2. This is associated with considerable costs and leads to a much more complex bottle top device. The primary aim of the invention is a manually operated bottle top device with electronic, in particular digital, measurement recording and display. To that extent show Fig. 1 , 3 and 4 that the piston drive 29 is designed for manual operation and the drive shaft 33 carries a manual operation knob 38 at one end or at each end outside the outer housing 2. You can see the two manual control knobs 38 on the left and right of the outer housing 2 in Fig. 1 .

Overall, according to preferred teaching, the gear connection between the drive shaft 33 and the pinion 35 is designed such that a rotation of the manual control knob 38 forward and downward causes a downward movement of the piston 27. Ergonomic studies have shown that good dosing accuracy can be optimally combined with the rapid absorption or dispensing of large quantities of liquid if the maximum stroke of the piston 27 corresponds to five to ten of the manual control knob 38.

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

The exemplary embodiment shown shows the piston rod 28, and the piston 27 is screwed to it by means of a central fastening screw 39, which here carries a sliding socket 40 which surrounds it on the bottom and on the circumference and is made of a very slippery material, in particular made of PTFE.

The sliding connector 40 forms a sliding ring 40a which rests under pressure on the cylinder 26 and is backed with a spring ring 42, which is supported on the piston 27 and made of a material which is preferably also chemically resistant, in order to generate pressure. The spring ring 42 is shown in the drawing as a hollow chamber ring, for example made of chemical-resistant elastomer material. It is important that the sliding ring 40a itself does not have to apply the force in order to achieve the sealing effect of the sliding connector 40 on the inner surface of the cylinder 26. This is done by the spring ring 42, which is adapted for this purpose. Incidentally, it can hardly be seen in the drawing that the outer peripheral surface of the slide ring 40a can still be structured, for example to realize a multi-start wiper ring.

For the accuracy that can be achieved with the bottle top device, it is also advantageous that, as provided in the exemplary embodiment shown, the piston 27 is not moved at the bottom against the valve block 10, but rather the piston rod 28 or the piston 27 is moved at the top against a stop 43. You can see the stop 43 in Fig. 4 . It interacts with a counterpart 43' on the piston rod 28. The stop 43 can be adjustable and should in any case be removable 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 to leave a small gap to the valve block 10 or to the bottom of the cylinder 26 even in the lowest position of the piston 27. Unevenness here cannot be a problem. The arrangement shown is particularly advantageous, in which the stop 43 engages near the piston drive 29 on the piston rod 28 which is firmly connected to the piston 27. As a result, the stop 43 and the force application point of the piston drive 29 on the piston rod 28 are close to one another.

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

For high accuracy when working with the bottle top device, it is advantageous if the inclusion of air bubbles in the liquid in the cylinder 26 can be recognized. In the event that the frame 30 is not designed as an open framework, but as an essentially closed housing, which is the case in the present exemplary embodiment (see in particular Fig. 2 and Fig. 4 ), it is recommended to provide the frame 30 with a front viewing cutout 44 or a corresponding window and, as provided here ( Fig. 5 ), with a rear viewing cutout 45 or a corresponding window. This means you can look into the glass cylinder 26 from the front or back.

Since we have an outer housing 2 here, a viewing cutout or a window in the frame would be of no use unless the outer housing 2 overlaps the viewing cutout 44; 45 or window of the frame 30 would have a corresponding viewing window 46 or 47. Such a viewing window can, if necessary, be colored to protect against UV rays, for example in brown. The front viewing 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 often used with chemically aggressive liquids that develop corresponding vapors. In particular, wetting of the inner wall of the cylinder 26 at the level of the piston rod 28 cannot be avoided and leads to corresponding vapors. It is therefore particularly advantageous to constantly ventilate the outer housing 2. For this purpose, ventilation openings 48 are recommended, which are expediently located in the middle to achieve convection, e.g. B. hidden under the manual control knobs 38, or are arranged at the bottom near the valve block 10 and at the top near the upper end of the outer housing 2. The illustrated and preferred exemplary embodiment shows that the top ventilation openings 48 are arranged at the head of the outer housing 2, preferably under an actuation button 49 arranged on the top.

You recognize in Fig. 1 On top of the top of the outer housing 2 there is a large actuation button 49, which is labeled here with the word "Clear", i.e. represents a zero position button. This is often used when working with a burette. The actuation button 49 on the top of the outer housing 2 is designed as a push button. They are actuated by pressure from above on the outer housing 2. This enables quick and error-free actuation without a serious tilting moment being exerted on the bottle top device and the storage bottle 1 underneath. Unlike the actuation buttons 6 arranged on the front of the outer housing 2, no counter-holding of the outer housing 2 is required.

The large operating button 49 also offers the possibility of hiding the ventilation opening 48 underneath. This shows Fig. 2 .

It has already been pointed out in connection with the explanation of the prior art that, for reasons of repair, cleaning and sterilization of the parts of the bottle top device that come into contact with media, it may be expedient to design the outer housing 2 to be openable. In the exemplary embodiment shown, it is provided that the outer housing 2 has a front housing shell 51 and a rear housing shell 52 which is detachably connected thereto. In the illustrated embodiment, see Fig. 2 and Fig. 5 , the front housing shell 51 is suspended at the rear of the valve block 10 and firmly anchored in the middle (or top) of the frame 30. It's screwed on there.

In the exemplary embodiment shown, the rear housing shell 52 is suspended at the top of the front housing shell 51. Below it is on the valve block 10 of the stopper 24, which sits in the stopper receptacle 23 and belongs to the bottle ventilation line 22. Other fixation options are also available, for example here using a screw. It is expedient to use the stopper 24 at the same time, also because it is particularly easily accessible from the back of the bottle top device. In Fig. 5 the rear housing shell 52 has been removed and accordingly the plug 24 is also missing.

The drawings, in particular Fig. 2 and Fig. 5 , show further special features of the interior design of the outer housing 2. First of all, in the outer housing 2, here in the front housing shell 51, more precisely attached to it, there is an area accessible from the back (as here), from the front and / or from above, to the interior of the Outer housing 2, however, is otherwise a closed receiving compartment 53. This receiving compartment 53 is used to accommodate electronic devices, in particular an equipped circuit board 54. The electronics of the display 4, including the display panel 5, are also located in the receiving compartment 53.

In the illustrated and preferred exemplary embodiment, in which the actuation button 49 is located on top of the outer housing 2, the receiving compartment 53 continues under the actuation button 49 at an angle into the rear housing shell 52. As a result, the electronic devices under the operating button 49 in this receiving compartment 53 can also be protected. In particular, this is another circuit board 55 that carries a push button 56 that is actuated by the actuation button 49. In the illustrated and preferred exemplary embodiment, this further circuit board 55 is connected to the circuit board 54 via a film hinge 57 and itself sits in an insertion socket 58 of the receiving compartment 53. In the illustrated and preferred exemplary embodiment, the film hinge 57 is formed by a circuit film web.

The receiving compartment 53 could be closed at the front by a compartment cover 59 which may also carry the display 4 and the operating buttons 6. Then The receiving compartment 53 could be equipped from the outside with the compartment cover 59 removed.

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

You can also see the receiving compartment 53 in the upper area, which extends to the rear housing shell 52 Fig. 2 and Fig. 5 another external connection 60. This is also sealed to the rear housing shell 52. The connection 60 represents an external interface of the electronic devices, which can be used in any usual way.

While in the representation in Fig. 2 the ventilation opening 48 below the actuation button 49 serves to ventilate the receiving compartment 53, are in Fig. 5 indicated ventilation openings located on the side under the actuation button 49 are also responsible for ventilation of the interior of the outer housing 2. You recognize in Fig. 5 in this context, the receiving compartment 53 is narrower than the outer housing 2, at least in the area extending backwards, and is arranged centrally.

Furthermore, you can see in Fig. 5 combined with Fig. 2 that in the outer housing 2, namely here in the front housing shell 51, ie attached to it, two battery compartments 61, namely to the right and left of the receiving compartment 53, are arranged. Each battery compartment 61 is otherwise closed to the interior of the outer housing 2 by a cover 62. The lid 62 is in Fig. 2 recognizable, it has a handling tab 63. In Fig. 5 You can see the battery compartments 61 without the covers 62 and without batteries. Of course, the battery compartments 61 are also sealed by the covers 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.

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

The openable design of the outer housing 2 with the essentially fixed front housing shell 51 and the easily removable rear housing shell 52 gives the user an easy way to disassemble the cylinder-piston arrangement, 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 sliding connector 40 if necessary.

Based on Fig. 3 Further special features of measured value acquisition will now be explained.

In the illustrated and preferred exemplary embodiment it is provided that the piston rod 28, preferably on the side opposite the row of teeth 34, carries a measuring strip 64 which extends axially on the piston rod 28 and that adjacent to the piston rod 28, preferably in the upper part of the frame 30, one Sensor arrangement 65 is arranged with a sensor 66 aligned with the measuring strip 64. Here, a direct measured value recording is provided on the piston rod 28, as is basically known from the prior art explained at the beginning. Backlash in translation devices, as occurs with electromechanical measurement recordings, is systematically excluded here. This is particularly useful here if the other measures to stiffen the mechanical arrangement and increase accuracy are also taken.

The exemplary embodiment shown shows that the measuring strip 64 is aligned on one side in a form-fitting manner on the piston rod 28. For this purpose, it is provided that the measuring strip 64 with a one-sided axial stop 67 is inserted into a pocket on the piston rod 28 and is potted with a preferably chemical-resistant potting compound 68. You can see a small amount of the casting compound 68 at the bottom of the stop 67 on the one hand, and on the other hand at the top end of the piston rod 28. A casting compound 68 is easier to make chemical-resistant than normal adhesives. It also has sufficient inherent elasticity to accommodate the minimal displacements of the measuring strip 64 relative to the piston rod 28.

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

The previously explained minimal displacements of the measuring strip 64 relative to the piston rod 28 arise from changes in the length of the piston rod 28 and from the different thermal linear expansion of the piston rod 28 and measuring strip 64.

In Fig. 12 the assembly with piston 27, piston rod 28 and measuring strip 64 is shown. In contrast to the execution according to Fig. 2 is the measuring strip 64 as in the version Fig. 11 a/11b arranged in the piston rod 28 near the central axis of the piston 27. The measuring strip 64 is also not as in the version 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 moved vertically downward onto the stop 67 by a spring element 28a. Both contact surfaces are inclined so that the measuring strip 64 is held in the direction of its lateral contact with the piston rod 28.

When executing after Fig. 12 the measuring strip 64 is not connected to the piston rod 28 over its vertical length.

The execution according to Fig. 12 holds the measuring strip 64 flexibly on the piston rod 28 by the spring element 28a. Temperature changes and different linear expansions have no influence on the fastening. In addition, the assembly of the measuring strip 64 without any aids and/or a curing time has a positive effect in terms of production and repair costs.

In the embodiment shown, the spring element 28a and the piston rod 28 are made in one piece. The spring element 28a could also be a separate component that is attached 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 a form-fitting manner in the direction of its lateral contact with the piston rod 28, for example by means of a molded-on bracket.

The structural details of a bottle top device described so far are not tied to the measuring principle of the position measuring system. According to preferred teaching, which is also shown in the drawings, a magnetic field-sensitive measuring system is used. However, optoelectronic and capacitive measuring systems can also be used for the different teachings of the present invention.

In detail, it is provided here that the distance measuring strip 64 (measuring strip 64) is magnetized in sections at a distance or magnetized in opposite directions in sections, with a pitch between 0.3 mm and 2.0 mm, preferably and as a compromise between resolution and costs approximately 1 .0mm.

The illustrated and preferred exemplary embodiment shows a particularly useful embodiment of a non-optical, in particular a magnetic field-sensitive, sensor arrangement 65. This is located in a receiving pocket 69 that is completely closed towards the measuring strip 64 or towards the interior of the outer housing 2. In the exemplary embodiment shown, this is in the Frame 30 inserted, namely on this with elongated hole connections 70 screwed. The elongated hole connections 70 allow the receiving pocket 69 to be precisely aligned with the measuring strip 64. In the illustrated and preferred exemplary embodiment, it is provided that the sensor 66 of the sensor arrangement 65 is arranged in the receiving pocket 69 on the side facing the measuring strip 64 behind a thin-layer wall section 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 towards the interior of the outer housing 2.

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

First you recognize in Figs. 6 and 7 that the sensor 66 of the sensor arrangement 65 sits on a circuit board 74 inserted into the receiving pocket 69 in an insertion guide 73, namely on its front edge, which is in Fig. 3 and Fig. 6 on the left directly rests against the thin wall section 71. The wall section 71 here, for example, only has a thickness of approximately 0.1 to 0.2 mm. If the pitch of the measuring strip 64 is chosen to be larger, the distance between the sensor 66 and the measuring strip 64 can also become larger. Wall sections that are easier to produce, in particular injection moldable ones, can then be designed, which will generally have a slightly larger wall thickness of around 0.5 mm.

The receiving pocket 69 here consists overall of a chemical-resistant and temperature-stable plastic material, in particular PEEK. The length and width of the receiving pocket 69 are approximately 20 mm, the thickness is approximately 8 to 10 mm.

The wall section 71 of the receiving pocket 69 can also not be made in one piece with the receiving pocket 69, but separately. It would then be attached to the receiving pocket 69. The can do this Receiving pocket 69 has an opening in the area of the wall section 71. A gas-tight film can be welded onto such an opening or fixed to the receiving pocket 69 in another way with or without auxiliary materials to close the opening. Such a gas-tight film usually has a thickness of approx. 10 µm to approx. 500 µm. This film now forms the wall section 71, which separates the sensor 66 from the measuring strip 64 in a gas-tight manner. In this way you can get to a very small distance of 0.1 mm or less.

The sensor arrangement 65 also has the evaluation circuit 72 on the circuit board 74 for evaluating the output signals of the sensor 66 and for controlling the display 4. In principle, it is possible to build the evaluation circuit 72 as a system solution with individual or several discrete components. A space- and energy-saving and cost-effective evaluation circuit 72 can be achieved by using a mixed-signal controller, which evaluates the converted analog sensor signals directly via interpolation software. The evaluation circuit 72 can also be implemented with an extreme case pure software solution using a microprocessor or microcomputer, without departing from the spirit of the teaching of the present invention.

Fig. 7 shows a perspective view of the receiving pocket 69 with the inserted circuit board 74 diagonally from behind. Here the circuit board 74 has not yet been cast. Likewise, the interface cable soldered to the circuit board 74 and cast in is not shown. You can plan to completely cast the circuit board 74 in the receiving pocket 69, also with a chemical-resistant casting compound.

What is interesting is the completely separate, block-like design of the sensor arrangement 65 in the receiving pocket 69 as an independently handled assembly of a device of the type in question.

Fig. 8 shows an arrangement of a particularly useful sensor 66 for a sensor arrangement 65 of a device according to the invention. Here it is envisaged that the sensor 66 is designed as a magnetoresistive sensor system based on the AMR effect is executed. For details of this operating principle please refer to the publication by Dr. Erik Lins, SENSITEC GmbH "Magnetoresistive with optical precision", dated August 1, 2005 , are referred to, the disclosure content of which is also made part of the disclosure content of the present application by reference. This publication has been freely accessible on the Internet since August 2005.

Fig. 8 Briefly shows two Wheatstone bridge circuits, offset by 45° from each other, so that a cosine signal (C) and a sine signal (S) are generated, taps at +C/-C and +S/-S. Operating voltage at Ub, against ground. The magnetization direction of the measuring strip 64 is defined by H, the angle between H and the direction of the current flow is given by β. By forming the quotient of sine and cosine (arc tangent function), the angle information becomes independent of the amplitude of the signals. On the one hand, this minimizes the influence of temperature, but 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 offers a certain redundancy and, due to the fact that the sum of the squares is equal to 1, allows self-monitoring of the sensor 66 or an offset amplitude correction.

In order to be able to carry out the direct evaluation of the sinusoidal and cosinusoidal signals from the sensor 66 as already explained above in order to achieve good interpolation, a circuit arrangement 72 as shown in Fig. 9 is shown as a block diagram. The sensor 66 is fed with a clocked supply voltage 80, which can be adjusted 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, and on the other hand to analog/digital converters 75 with downstream modules 85 and normalization stages 86. The modules 75, 85, 86, 87, 88 and 89 are in The present, preferred solution is implemented in a mixed-signal controller. For further For information about a mixed-signal controller, please refer to the relevant statements and the citation contained 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, quadrant recognition takes place in stage 87. All signals are then fed to the interpolation stage 88, in which an ARCTAN table is stored. According to 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 is carried out in a correction stage 89 according to the formula $${\mathrm{Dsin}}^{}$$$${}^2\mathrm{\beta }+{\mathrm{<figure-callout\; id="2"\; label="Dcos"\; filenames="imgf0001.png"\; state="\{\{state\}\}">Dcos</figure-callout>}}^2\mathrm{\beta }={\mathrm{A}}^{\prime 2}.$$

With regard to the power consumption of the measuring system, a magnetoresistive measuring system is already quite useful, and at least much cheaper than an optoelectronic measuring system. According to preferred teaching, it is further provided here that the evaluation is carried out using the interpolation software 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 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 works with an interpolation rate between 200 and 1,000, in particular between around 400 and around 600, preferably around 500.

You can see this keying in the schematic representation in Fig. 10 . You can see the course of the sine curve sampled here. The time for recording measured values is an ON time of 200 µs marked by vertical blackened lines shown. In the gaps between the lines, the OFF time is 5.6 ms. The duty cycle is therefore approximately 0.036 in this exemplary embodiment.

Compared to the interpolation ICs known from the prior art, if the intended interpolation is implemented with an interpolation rate of approximately 500, the current consumption can be reduced to approximately 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. The mixed-signal controller mentioned as an example in the introduction to the description has, for example, five different power-saving modes (page 6 of the data sheet there), all of which are characterized by the fact that the central processing unit (CPU) is switched off. In general, such a mixed-signal controller with different power-saving modes is to be preferred because it can be optimally tailored to the special features of a device according to the invention.

It has been assumed here that with a manually operated device of the type in question, the adjustment speed of the piston 27 will not be greater than approximately 50 mm/s. The interpolation rate is tailored to this. This gives you a resolution of the measuring path of around 2 µm and an accuracy of the measured value over the full measuring range of around 10 µm, all in a temperature range of + 10 °C to around + 40 °C.

Another and independent teaching is based on the exemplary embodiment of Fig. 11 (Fig. 11a, Fig. 11b ) explained. In the illustrated and preferred exemplary embodiment, this construction applies to a magnetic field-sensitive sensor system, in particular a magnetoresistive sensor system.

Fig. 11a shows an exact alignment of the piston rod 28 on a side guide 90. What is intended here is that on the same side on which the Sensor arrangement 65 is located, a side guide 90 is provided for the piston rod 28 and the sensor 26 is arranged close to, preferably approximately at the height of, the side guide 90. This ensures that when the piston rod 28 is in the desired position in contact with the side guide 90, the sensor 66 is also exactly aligned relative to the measuring strip 64 positioned on the piston rod 28. The parallelism of the measuring strip 64 with the sensor 66 is optimal over the full adjustment path of the piston rod 28.

Fig. 11b shows in connection with Fig. 11a 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 is noticeable in a device of the type in question because of the high precision achieved. It is caused by the fact that the piston rod 28 has a certain lateral play in the area of the piston drive 29, for example 0.3 mm. This leads to a minimal but disturbing inclination of the piston rod 28 within the scope of the present measurement accuracy, which causes a position measurement error.

In the case of an optical measurement, it is now recommended to make this error as small as possible by arranging the measuring strip 64 on the piston rod 28 on the one hand and the sensor arrangement 65 with the sensor 66 on the other hand in such a way that when the piston rod 28 is in the desired position the surface of the measuring strip 64 facing the sensor 66 forms a plane which lies as close as possible to or 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 knowledge that in an incident light system, the surface of the measuring strip 64 is the interface between the measuring strip 64 and the sensor 66. If I place this as close as possible to the longitudinal central axis of the piston rod 28, I minimize the measurement error that results from the inclination of the piston rod 28 due to play.

In the case of the magnetoresistive measuring system preferred according to the invention, however, the sensor 66 which detects the magnetic field of the measuring strip 64 applies lies as close as possible to or on the longitudinal central axis of the piston rod 28. This is in Fig. 11a, b shown. 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. If the measuring strip 64 tilts as in Fig. 11b shown to the left, the starting area of the field lines moves slightly downwards, but at the same time the direction of the field lines is also tilted due to the tilting, these run from the measuring strip 64 slightly upwards in the direction of the sensor 66. At the interface, namely at the sensor 66, only the amplitude changes slightly, which can be corrected, but not the phase position, which is crucial for the distance measurement.

For a capacitive sensor system with a corresponding measuring strip 64, the interface lies somewhere between the two orientations described above.

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

With the relative position of the measuring strip 64 and sensor 66 realized according to this special teaching of the invention, the sensor 66 in the sensor arrangement 65 is no longer next to the piston rod 28, but in its clear profile. Accordingly, it is recommended that the piston rod 28 has a recess or flattening that allows the corresponding position of the sensor 66.

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

In principle, the above statements apply to the exemplary embodiment of Fig. 11a, b also for an off-center arrangement of the piston rod 28. Of particular importance, however, is the design in which the piston rod 28 is guided by the side guide 90 - in connection with the piston 27 in the cylinder 26 - with its longitudinal central axis as close as possible to or on the longitudinal central axis of the cylinder 26 becomes.

The exemplary embodiments shown show that the sensor arrangement 65 is not arranged on the outer housing 2, but on the dimensionally stable frame 30. This means that the entire measurement 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 has already been explained above, it can be provided that the measuring strip 64 is an optical scale and the sensor arrangement 65 is a high-resolution reflected light system, in particular with four reflected light diodes. Then the construction in the area of the sensor arrangement 65 is of course different than previously described.

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% for nominal volumes of 25 ml and 50 ml. These are values that are otherwise only achieved by high-precision motorized bottle top devices. The high accuracy of the bottle top device according to the invention also stems from the fact that all mechanically moving parts are fixed axially with respect to the valve block 10 precisely and dimensionally stable. This, in conjunction with the direct measurement measurement directly on the piston rod 28, makes it unnecessary to compensate for play when reversing the actuation direction.

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

Claims (6)

1. Bottle attachment for handling liquids with

   - a cylinder-piston arrangement for precisely taking up and dispensing partial volumes of liquid, having a cylinder (26) and a piston (27) running in a sealedoff manner in the cylinder (26),

   - a displacement measuring strip (64),

   - a sensor arrangement (65) with a sensor (66) aligned with the measuring strip (64) and separated from the measuring strip (64) only by a narrow gap, the sensor arrangement (65) being arranged in a receiving pocket (69) which is completely closed towards the measuring strip (64),

   - an indicator (4) for the quantity of liquid handled or to be handled, and

   - an electronic evaluation circuit (72) for evaluating the output signals of the sensor (66),

   characterized in that

   the piston (27) has a piston rod (28) extending upwards out of the cylinder (26),

   in that the displacement measuring strip (64) is arranged directly on the piston rod (28) and extends axially in the direction of movement of the piston rod (28), and that the sensor arrangement (65) is arranged in a fixed position in the device adjacent to the piston rod (28) .
2. Bottle attachment according to claim 1, characterized in that the sensor arrangement (65) in the receiving pocket (69) is designed as a completely separate, block-like assembly which can be handled independently.
3. Bottle attachment according to claim 1 or 2, characterized in that

   - the bottle attachment has an outer housing (2) and can be attached to a bottle neck of a storage bottle (1) by means of a fastening arrangement (3),

   - the bottle attachment has a valve block (10) in the outer housing (2), to which the fastening arrangement (3) is attached or integrally formed, with which the valve block (10) can be fastened to the storage bottle (1),

   - the outer housing (2) is detachably connected to the valve block (10),

   - the bottle attachment has a supporting frame (30) surrounding the cylinder (26) and extending upwards beyond the cylinder (26),

   - the frame (30) is firmly connected at the lower end to the valve block (10) in a precisely defined axial position, but can be detached from the valve block (10),

   - the bottle attachment has a piston drive (29) connected to the piston rod (28) above the cylinder (26),

   - the frame (30) accommodates or supports the piston actuator (29),

   - the outer housing encloses the frame (30) on the outside, extends upwards beyond the piston drive (29) on the frame (30) and is closed at the top, and

   - the sensor arrangement (65) is arranged in the upper part of the frame (30).
4. Bottle attachment according to one of the preceding claims, characterized in that the sensor (66) is arranged in the receiving pocket (69) on its side facing the measuring strip (64) behind a thin-layer wall section (71) of the receiving pocket (69), the wall section (71) having a thickness of approximately 0.1 mm to 0.5 mm.
5. Bottle attachment according to one of the preceding claims, characterized in that the sensor arrangement (65) in the receiving pocket (69) is potted at the rear with potting compound.
6. Bottle attachment according to one of the preceding claims, characterized in that the sensor (66) of the sensor arrangement (65) is seated on a circuit board (74) inserted in the receiving pocket (66) in an insertion guide (73) at the front edge thereof.

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