EP1476728A1

EP1476728A1 - Volume meter with wet volume scanning

Info

Publication number: EP1476728A1
Application number: EP03708106A
Authority: EP
Inventors: Hermann Senf
Original assignee: Bopp and Reuther Messtechnik GmbH
Current assignee: Bopp and Reuther Messtechnik GmbH
Priority date: 2002-02-22
Filing date: 2003-02-18
Publication date: 2004-11-17
Also published as: DE10207454A1; DE10207454B4; WO2003071238A1; AU2003212247A1

Abstract

The invention relates to a volume meter comprising a measuring chamber which is arranged inside a housing, and through which a liquid flows. Said volume meter also comprises at least one rotor which is rotatably mounted in the measuring chamber such that it is perpendicular to the flow direction of the liquid. A volume flow of the liquid can displace said rotor in a rotational movement which can be used to quantitatively measure the volume flow. At least one signal generator is connected to the rotor in a rotationally fixed manner. The volume meter comprises a sensor for signal formation, said sensor being arranged in the housing. The inventive volume meter is characterised in that the at least one signal generator is a flat signal disc comprising defined regions which can be detected by the sensor, and the at least one signal disc is arranged directly above the rotor(s), on a projection thereof, outside the measuring chamber but inside the housing.

Description

Volume counter with wet room scanning

The invention relates to a volume meter with a measuring chamber arranged within a housing, with at least one rotor arranged within the measuring chamber, rotatably mounted and rotatable by a volume flow of a fluid, the measuring chamber through which the fluid can flow perpendicular to the axis of the at least one rotor , and with at least one signal transmitter connected in a rotationally fixed manner to the one or more rotatable rotors and with at least one sensor for signal formation inserted into an end wall of the housing facing the signal transmitter (s).

The invention is based on a prior art, as is known from DE 33 00 657 AI, DE 34 42 358 C3 or CH 576 629 A5.

Volumeters or flowmeters are therefore known in a variety of different designs, such as oval gear meters, gear meters, bi-rotor meters, traction slide or ring piston meters, all of which are based on a basic, common functional principle: there is at least one rotor within a measuring chamber through which a fluid can flow arranged, which is set in rotation by the flowing fluid, the Rotationsge ^¬ speed of the rotor can be used as a measure of the fluid volume flowing through the meter. In order to To be able to carry out a meaningful evaluation of this rotary movement, it is necessary to detect it in a suitable manner by sensors.

DE 33 00 657 AI relates to an oval wheel meter, in which one end face is equipped with a permanent magnet and in which a corresponding magnetic field sensor arrangement is provided above the oval wheel end faces. However, in terms of area, the oval end faces generally only permit the attachment of a small number of magnets, since a necessarily circular arrangement with a suitable division can only take place in the hub area of the oval wheels. This has a disadvantageous effect, in particular, on the size of the measuring range and the measurement value resolution. An arbitrarily close arrangement of a plurality of permanent magnets is also not possible due to the strong magnetic stray fields of such an arrangement, since there is a risk of incorrect measurements. This aspect is particularly problematic in the case of volume counters in which the rotor or the rotors perform non-uniform rotational movements, for example in the case of oval wheel counters. In order to achieve a high measurement value resolution with such volume counters, a plurality of signal transmitters must be in volume-proportional, i.e. distances adapted to the variable rotational speed, which are very narrow in some areas due to the reduced rotational speed. A further disadvantage is that due to the arrangement of the permanent magnets associated with structural changes to the rotors, a subsequent flexible change or adaptation of the measuring range or the resolution of the measured values is practically no longer possible or would be associated with considerable effort.

DE 34 42 358 C3 relates to an impeller counter with permanent magnets inserted into the impeller. Here too give the disadvantages listed above due to the design.

In the case of CH 576 629 A5, parts made of ferromagnetic material are provided on an extension of a rotor equipped with a paddle wheel on a timing gear, which produce a measuring pulse on a sensor with each revolution of the timing gear tooth, so that the corresponding problem, in particular regarding the Measured value resolution of such a volume counter results. In addition, the measuring principle disclosed can only be used with volume counters whose rotors rotate at exactly the same angular velocity.

Similar disadvantages also arise for known sensor arrangements in a hollow rotor shaft, e.g. for sensor arrangements based on the Wiegand principle. The arrangement of a Wiegand sensor in a hollow shaft is structurally demanding, and the associated control electronics are complex and complex. The same applies to the calibration of such a sensor. A rotary movement is detected by means of short pulses, the duration of which does not depend on the speed of rotation of the rotor. For this reason, sensors of this type have disadvantages, particularly in the case of low flow rates (quasi-static operation). Due to the cramped space, there is also only a small amount of constructive freedom, which is associated with a correspondingly increased design and manufacturing outlay.

The invention is based on the problem of designing a generic volume meter while avoiding the disadvantages listed above in a structurally simple and thus inexpensive manner in terms of production in such a way that a safe, high-resolution and at the same time flexible Signaling for a downstream evaluation electronics is guaranteed even with very low flow rates, which is associated with ease of installation and ease of use.

This object is achieved according to the invention with a generic volume counter, which is characterized in that the signaling device (s) is or are a flat signal disk or flat signal disks with delimited areas that can be detected by the sensor, and that the at least one signal disk is located directly above the rotor or the rotors are arranged on an extension of the rotor or the rotors outside the measuring chambers, but inside the housing. A major advantage of the solution according to the invention is that the cross section of the housing or the volume measurement area swept by the rotor can be used optimally, regardless of the type of construction, and thus the measurement resolution is increased compared to known volume counters. Another advantage of the invention is that no sealing of shafts, in particular of the encoder rotors, is required and therefore the friction is minimized.

In a preferred embodiment of the invention it is provided that the signal disks are designed as flag disks or as perforated disks. Such signal disks can be produced in an extremely simple manner by laser cutting or punching from a metal sheet and are therefore particularly inexpensive to manufacture.

In addition, the applicability of the invention, in particular due to a preferred configuration of the signal transmitters, is not restricted to meter types in which the rotor or, if appropriate, a plurality of rotors rotate at the same angular velocity. Accordingly, in a further development of the invention, the signal disks have been designed as sensor-detectable provide a volume-proportional arrangement of projections or holes. Here and in the following, “volume-proportional” means that the sensor-detectable areas of the signal disks are not arranged equidistantly and, moreover, do not have identical widths, but are designed such that, with the same volume flow rate, a non-uniform rotational movement of a rotating component may occur of a volume counter is compensated, as is the case, for example, with oval gear meters. Rather, one applies to the widths or distances B, B 'of the sensor-detectable regions of the signal disk

Relationship of the form B, B ¹ ~ τπ, where xs indicates the instantaneous angular velocity of the rotor as the corresponding detectable areas of the signal disk move past the location of the sensor. In any case, this results in a uniform pulse train at the sensor, which increases the measuring accuracy and facilitates the subsequent evaluation. In addition, in this way there is also a simple possibility of adaptation to any type of meter, for example pinion meter or impeller meter, in which the wheels execute a substantially uniform rotary movement.

However, the invention is particularly important when the meter is designed as an oval wheel meter, since such meters are characterized by their particularly broad range of applications and, moreover, by the relatively large measurement volume per rotor revolution, e.g. in comparison with the subject matter of CH 576 629 A5, allow better resolution and measuring accuracy if the irregular rotation of the rotors is balanced in the manner according to the invention.

According to a further preferred embodiment of the invention, it is provided that at least two signal disks are on a single rotatable component of a volume counter are arranged. In particular, the signal disks can be arranged relative to one another in such a way that a specific phase shift of the signals results at the corresponding assigned sensors. By providing a plurality of signal disks and sensors, a plurality of signals with any desired pulse-pause ratios and any phase offset can be generated accordingly. In this way, the measurement value resolution of the volume counter can be adapted to specific requirements, as well as a detection of the running direction of the counter, ie the direction of flow of the fluid. In an extremely preferred embodiment of the invention, it is also possible to combine a plurality of signal disks to form a single component, which in this case is simultaneously designed as a flag and perforated disk with a plurality of concentrically arranged signal tracks made of projections or holes. In this way it is possible to minimize the number of components required and consequently to optimize the required installation space even further.

The signal formation is preferably carried out inductively, and inexpensive commercially available sensors can be used. In the course of a corresponding configuration of the invention, the signal disks are preferably made of a material that can be detected by inductive proximity sensors, in particular of chromium steel or chromium-nickel steel in V2A or V4A quality. Alternatively, the signal disks can be made of copper or aluminum, for example. Especially the measuring aggressive fluids is the Ver ^¬ application widerstandsf higer, stainless steel discs as a signal transmitter beneficial to ensure a long service life of the device according to the invention. The signal disks accordingly have, with their projections and / or holes, delimited ferromagnetic regions in which an presence or absence of signal disk material can be detected by the sensors used.

According to a further embodiment of the invention, the signal is generated magnetically. In this case, the signal disks have defined magnetized areas or have magnetized components in some areas, in particular in the form of permanent magnets. The sensors are preferably designed as magnetic field sensors. In the course of this configuration, materials can also be used to manufacture the signal disks that cannot be detected with inductive proximity sensors, but whose use may be indicated with a view to certain material-damaging properties of the fluid. This applies in particular to the possible use of plastic signal disks with permanent magnets. In the case of magnetic signal formation, too, the corresponding magnetized subregions or the magnetic assembly of the signal disks are preferably designed to be volume-proportional.

A further development of the subject matter according to the invention provides that the sensors are inserted in a sealed manner into a sensor holder, in particular are screwed in. The provision of sensor holders enables the use of a wide variety of commercially available sensors, since in this way an adaptation of the sensor geometry to the structural conditions of the volume meter can be achieved. The sensor holders are preferably arranged sealed in corresponding bores, which are advantageously provided in a flat cover of the meter housing. Such an embodiment is characterized in particular by a high degree of variability with regard to the relative and absolute positioning of the sensors. In this way, when using a plurality of signal disks or tracks, the associated sensors can be relative to one another arrange such that individual signal channels have a certain phase angle to one another. When using two signal disks or tracks and correspondingly two sensors, the channels preferably have a relative phase angle of 90 ° for forward and 270 ° for reverse running of the counter. The direction of rotation of the counter can thus be specified on the basis of the relative phase position of the channels.

A further development of the invention provides that the housing of the sensor itself is designed as a sensor holder. The sensor housing is preferably sealed off from the meter housing by means of an O-ring which is arranged in a groove provided on an outer circumferential surface of the sensor holder. In this way, according to an extremely preferred embodiment of the invention, it is possible to move the sensor holders and thus the sensors in the direction of their longitudinal axes for the purpose of axial adjustment of the sensors, thereby ensuring an optimal sensor-dependent switching distance. In connection with a suitable signal disk material according to the invention and a suitable dimensioning according to the invention of the defined areas, the sensors thus deliver a stable and unambiguous output signal even with a flow rate of zero (and correspondingly disappearing rotor rotation).

In the embodiments of the invention that have been discussed so far, the sensors are in contact with the fluid, ie they are immersed at least with their front side in the fluid. Can be according to a highly preferred embodiment of the invention is, however, also be provided that the sensor holder is det ausgebil ^¬ a full housing, then the sensor electronics that completely in the drying chamber is located, and thus also with integrated sensor and fluidbefülltem counter interior exchanged. With such a configuration, it is not necessary to have a fluid delivery system in which a volume counter is used to stop and empty the meter interior before replacing or checking the sensor electronics.

The present invention is explained in more detail below on the basis of exemplary embodiments. The associated drawings show:

Fig. La is a sectional view of an oval gear meter with measuring chamber integrated in the meter housing and two sensors and a signal disk;

FIG. 1b shows a top view of a volume counter similar to the volume counter of FIG. La;

2a shows a sectional view of an oval wheel meter with a separate measuring chamber and two sensors and two signal disks;

FIG. 2b shows a top view of a volume counter similar to the volume counter of FIG. 2a;

3a shows a sectional view of an oval gear meter with a separate measuring chamber and two sensors and a signal disk;

3b is a top view of a volume counter similar to the volume counter of FIG. 3a; and

Fig. 4 is an oscilloscope representation of the sensor signals of a pulse tap according to the invention with two sensors.

FIG. 1 a shows a volume meter in the form of an oval wheel meter 1 with a measuring chamber integrated in a meter housing 2. mer 3. The housing 2 has in its side wall diametrically opposite one another a fluid inlet 2a and a fluid outlet 2b. Below a measuring chamber end cover 4, two oval wheels 5, 5 ¹ are mounted in a manner known per se by means of two vertical, rotatably mounted, parallel shafts A, A 'or rotatable about corresponding (housing-fixed) axes. One oval wheel 5 has a certain projection or an extension 6 with respect to the upper side of the measuring chamber end cover 4, at the end of which a signal disk 7 made of ferromagnetic material is arranged perpendicular to the direction of the shafts A, A '. The signal disk 7 is essentially designed as a circular disk and has two concentric signal tracks with sensor-detectable defined areas which are formed from holes 8 or projections 9, the presence or absence of signal disk material being registered in each case.

The counter housing 2 is closed at the top by a flat housing cover 10. Two sensor holders 11, 12 are arranged in the holes provided for this purpose. Inductive proximity sensors 13 are inserted into them in such a way that the tip 14 of the sensor 13 is located directly above the signal disk 7 in the region of one of the two signal tracks. The sensor holders 11, 12 have a flange 15 above the housing cover 10. A washer 17 is inserted as a spacer between this flange 15 and the top 16 of the housing cover 10.

FIG. 1b illustrates the concentric arrangement of the two signal tracks of the signal disk 7 formed from projections 9 or holes 8. The signal tracks of the signal disk 7 have a volume-proportional division. That is, the holes 8 and projections 9 have widths B, B ¹ which are not constant over the circumference of the signal disk 7, but rather explained above according to B, B ¹ ~ tπ are adapted to the instantaneous rotational speed of the oval wheels 5, 5 '. The sensor holders 11, 12 are arranged above the signal disk 7 in such a way that one sensor is located above the inner and the other sensor above the outer signal track. The relative arrangement of the sensors is selected such that one sensor is located just above a gap between two projections 9 of the signal disk 7, while the other sensor, depending on the direction of flow of the fluid, is still or already above an inductively detectable part 9 of the signal disk 7 located. In this way, the two sensors deliver the signals shown in FIG. 4, by means of which both the speed of rotation and the direction of rotation of the oval wheel 5 and thus the flow rate and the flow direction of the fluid can be derived.

The use of washers of different thicknesses or a plurality of washers 17 between the sensor holder flange 15 and the upper side 16 of the housing cover 10 enables simple axial adjustment, i.e. a displacement of the sensor holder 11, 12 in the direction of their longitudinal axes and thus an adjustment of the sensors 13, whereby an optimal working distance of the sensor tip 14 to the signal disk 7 can be set.

In the embodiment of the invention shown here, in addition to the two oval wheels 5, 5 ', there is only a single further moving component, the signal disk 7, which results in a particularly simple embodiment.

By relocating the pulse tap into the pressure compensation space between the measuring chamber cover 4 and the housing cover 10, significant improvements in the tap design options can be achieved, in particular The generous amount of space allows a high number of impulses with exact volume-proportional division.

This means that the inductive sensors used also have a static function, i.e. Remaining on or off for any length of time, safe signaling can be achieved even with very low flow rates (creeping amounts). A complete standstill of the volume counter is also reliably detected.

In the event that the sensor holders 11, 12 are designed as full housings, they are completely sealed off above the signal disk 7 against the interior of the meter, so that the sensor 13 or the sensor electronics can be replaced even when the volume meter 1 is in operation in the fluid-filled state can.

FIG. 2a shows a volume counter which essentially corresponds in its construction to the oval wheel counter shown in FIGS. 1a and 1b. However, here the measuring chamber 3 is not integrated into the meter housing 2, but is designed as a separate component within the housing 2.

On the extension 6 of the oval wheel 5, two signal disks 7, 7 'are arranged in parallel and at a certain distance from one another, the upper signal disk 7 ¹ having a reduced diameter compared to the lower signal disk 7. This Mindermaß the upper signal disc 7 'is designed such that the signal track of the lower disk 7 nalscheibe signal along the full circumference of the lower Sig ^¬ exposed. 7 The sensor holders 11, 12 introduced into the cover 10 of the counter housing 2 are designed or arranged in such a way that one sensor 13 is at an optimal working distance from the signal track of the lower signal disk 7, while the other is in one just such distance to the signal track of the upper signal disk 7 'is arranged.

Provided above the measuring chamber 3 is a guide part 19 with a U-shaped cross-section, which rests with the ends of its free legs on the upper side of the measuring chamber 3 and has a bore 20 in its central region which runs parallel to the upper side of the measuring chamber 3 and which receives the extension 6 of the shaft A of the oval wheel 5 is used.

2b shows the design of the signal disks 7, 7 'as flag disks, so that the signal tracks are formed by projections 9 designed or arranged in proportion to the volume. In the exemplary embodiment shown here, too, the sensor holders 11, 12 are arranged in the cover 10 of the counter housing 2 in such a way that a sensor is arranged over a gap in the first flag disk 7 ′, while the second sensor is still or already partially over a front - Jump 9 of the other flag 7 is located.

In a groove provided on the outer circumferential surface of the sensor holders 11, 12, an O-ring 18 is arranged, which effects a seal between the sensor holder 11, 12 and the cover 10 of the counter housing 2.

FIG. 3a shows an oval gear meter, which represents a combination of the systems shown in FIGS. 1a, b and 2a, b.

The volume meter 1 shown here has a measuring chamber 3 arranged separately within the meter housing and moreover has a single signal disk 7 which has two concentric signal tracks made of projections 9 and holes 8 which are designed or arranged in proportion to the volume. Above the top of the measuring chamber 3 is a Guide part 19 with a bore 20 for receiving the extension 6 of the oval wheel 5.

FIG. 3b shows once again the configuration of the signal disk 7 known from FIG. 1b with two concentrically arranged signal tracks in use in a volume counter 1 with a separate measuring chamber 3 known from FIG. 2a.

4 shows the output signals of two sensors of a volume counter 1 according to FIGS. 1 a to 3 b, in which the sensors are arranged in such a way that the sensor signals have a relative phase position of 90 ° when the volume counter 1 is running forward and 270 ° when it is running backwards. In the measurement example shown here, the signal SI of the first sensor leads the signal S2 of the second sensor by a quarter of a signal period T, which indicates that the volume counter 1 is running forward. If the counter were to run backwards, the signal S2 would additionally be shifted by 180 °, ie by half the signal period T compared to the signal SI. The effect of the volume-proportional design of the signal tracks of the signal disks 7, 7 ¹ can be clearly seen from the regularity of the expression and the time sequence of the sensor pulses.

The drawings described above are only exemplary and in no way restrictive. In addition to the illustrated use of the device according to the inventiveness in oval gear meters in particular also for use with other known types of Volu ^¬ is menzählern such as gear meters, blowing shifters, Bi -Rotor- meters and rotary piston meters readily possible.

LIST OF REFERENCE NUMBERS

1 volume counter (oval gear meter)

2 counter housings

3 measuring chamber

4 measuring room end cover

5, 5 'oval wheels

6 extension of 5

7, 7 'signal discs

8 holes

9 head start

10 housing cover

11, 12 sensor holder

13 sensor

14 sensor tip

15 flange

16 top of the housing cover (10)

17 washer

18 O-ring

19 guide part

20 hole

A, A 'axes of rotation / shafts

B, B 'width

SI, S2 sensor signal

T signal - period

Claims

claims

Volume counter (1) with a measuring chamber (3) arranged within a housing (2), with at least one rotatably mounted rotor (5, 5 ¹ ) arranged within the measuring chamber (3) and rotatable by a volume flow of a fluid, the fluid can flow through the measuring chamber (3) perpendicular to the axis of the at least one rotor (5, 5 ¹ ), and with at least one signal transmitter connected to the one or more rotatable rotors (5, 5 ') in a rotationally fixed manner and with at least one sensor (13) inserted into a front wall of the housing facing the signal transmitter (s), characterized in that

that the signal transmitter (s) is or are a flat signal disk (7, 7 ') or flat signal disks (7, 7 ¹ ) with delimited areas which can be detected by the sensor

- That the at least one signal disc (7, 7 ') directly above the rotor (5, 5') or the rotors (5, 5 ¹ ) on an extension of the rotor (5, 5 ') or the rotors (5, 5 ¹ ) outside the measuring chamber (3), but inside the housing. Volume meter according to claim 1, characterized in that the signal disks (7, 7 ') are designed as flag disks.

Volume meter according to claim 1, characterized in that the signal disks (7, 7 ") are designed as perforated disks.

Volume meter according to claim 2 or 3, characterized in that the signal disks (7, 7 ') have a volume-proportional arrangement of projections (9) or holes (8).

Volume meter according to one of the preceding claims, characterized in that a signal disk (7, 7 ') is arranged on at least two different rotors (5, 5').

Volume meter according to one of claims 1 to 4, characterized in that at least two signal disks (7, 7 ') are arranged on a single rotor (5).

Volume meter according to claim 6, characterized in that the signal disks (7, 7 ¹ ) are combined to form a single component (7) which at the same time acts as a flag and perforated disk with concentric signal tracks from projections (9) or holes (8). is trained.

Volume meter according to one of the preceding claims, characterized in that the sensors (13) are designed as inductive proximity sensors.

Volume counter according to claim 8, characterized in that the signal disks (7, 7 ') from an inductively tive feeders (13) detectable material, in particular made of copper or aluminum.

Volume meter according to claim 8 or 9, characterized in that the signal disks (7, 7 ') consist of chromium steel or chromium-nickel steel in V2A or V4A quality.

Volume meter according to one of claims 1 to 7, characterized in that the sensors (13) are designed as magnetic field sensors.

Volume counter according to claim 11, characterized in that the signal disks (7, 7 ') have defined magnetized areas.

Volume counter according to claim 11 or 12, characterized in that the magnetized areas of the signal disks (7, 7 ¹ ) are formed by a magnetized assembly, in particular in the form of permanent magnets.

Volume counter according to claim 12 or 13, characterized in that the magnetized areas of the signal disks (7, 7 ¹ ) are formed in proportion to the volume.

Volume meter according to one of the preceding claims, characterized in that the sensors (13) are each inserted in a sealed manner into a sensor holder (11, 12), in particular are screwed in.

Device in that the housing (2) has a sentlichen in ^¬ we flat cover (10) according to any one of the preceding claims, characterized in that. Volume meter according to claim 16, characterized in that the sensor holders (11, 12) are arranged sealed in the bores in the cover (10) of the housing (2).

Volume meter according to claim 17, characterized in that the sealing takes place by an O-ring (18) which is arranged in a groove provided on an outer peripheral surface of the sensor holder (11, 12).

Volume meter according to one of claims 15 to 18, characterized in that the sensor holders (11, 12) are displaceable in their longitudinal direction for the axial adjustment of the sensors (13).

Volume meter according to one of claims 15 to 19, characterized in that the axial adjustment of the sensors (13) can be carried out by means of washers (17) which are provided between a flange (15) provided on the sensor holder (11, 12) and the upper side ( 16) of the housing cover (10) are arranged.

Volume meter according to one of claims 15 to 20, characterized in that the sensor housing is designed as a sensor holder (11, 12).

Volume meter according to one of Claims 15 to 21, characterized in that the sensor holders (11, 12) are designed as full housings, so that the electronics of the sensor (13) can be removed when the sensor (13) is installed and the interior of the meter is filled with fluid.

Volume meter according to one of the preceding claims, characterized in that when using a multiple number of signal disks (7, 7 ') or tracks, the associated sensors (13) are arranged relative to one another in such a way that individual signal channels have a specific phase angle to one another.

24. Volume meter according to claim 23, characterized in that a flow direction can be detected by the relative phase position of the individual channels.

25. Volume meter according to claim 23 or 24, characterized in that when using two signal disks (7, 7 ") or tracks and two sensors (13), the channels have a phase angle of 90 ° with forward and 270 ° with reverse running of Have counter (1).

26. Volume meter according to one of the preceding claims, characterized in that the signal disc (s) (7, 7 ¹ ) is or are produced by laser cutting.

27. Volume meter according to one of the preceding claims, characterized in that the signal disc (s) (7, 7 ¹ ) is punched or are.