Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Mechanical measurement system
Reexamination Certificate
2001-02-13
2003-07-29
Shah, Kamini (Department: 2863)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Mechanical measurement system
C702S045000, C073S861640, C073S29000R
Reexamination Certificate
active
06601000
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC
Not Applicable
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The invention relates to a device for conveying a medium from a container into a tank and for determining the quantity of the medium, having a conduit between the container and the tank, a conveying device connected to the conduit and a device for separating gas from the medium. The invention also relates to a method for conveying a medium from a container into a tank and for determining the quantity of the medium, in which the medium is transported via a conveying device and a conduit and gas absorbed by the medium is separated.
Such devices and methods are used in the most varied fields, such as e.g. in dairying or the distribution of fuels.
In the dairying sector a tank truck regularly visits certain milk producers and removes there the milk which has e.g. been produced during the course of a day from one or more storage containers. It is particularly important that the milk quantity removed is precisely measured and recorded, because it is on this basis that a subsequent settlement of account takes place between producer and customer. Therefore high demands are made on the quality of the quantity measurement, which is illustrated by the fact that legal regulations exist with regards to the calibrations and the quality of the measured results.
In order to meet these high demands it is necessary to minimize possible measurement errors. A particularly serious measurement error only eliminatable with a certain apparatus expenditure results from the fact that e.g. the milk is enriched with air during the removal process by pumps or the like and this leads to a more or less pronounced frothing of the milk. Thus, prior to the actual quantity measurement air separation must take place. Therefore in most prior art devices and methods the milk is firstly supplied to an air separator, where it remains until adequate degassing has occurred and is only then supplied via a flowmeter to the tank to be filled.
(2) Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
In the Federal Republic of Germany there is e.g. a standard (DIN 19217: 1997-11), which contains strict regulations relating to air separation (cf. therein section 2.10.2). The technical features given in the DIN form the preambles of the independent claims. The DIN prescribes that in order to fulfil the calibration requirement the gas separator must be a separate component of the installation. This leads to problematic high apparatus costs. In addition, in the case of installations having a separate gas separator, as prescribed by the DIN, the aforementioned time lag problem occurs during the conveying of the medium, because it must in the meantime remain in the air separator. Thus, EP 626 567 B1 already proposes a flowmeter, which even in the case of air-freighted milk is able to sufficiently accurately determine the volume. However, this intrinsically satisfactorily operating device and the method performed by it are comparatively complicated and consequently require improvement.
DE 33 19 277 A1 discloses a float for a level control provided in an inner chamber of a milk container. The milk level is determined in that the float interior contains a magnet, which interacts with a permanent magnet inside a dipstick.
EP 806 636 A1 also discloses a device for determining the level, in this case in aircraft tanks. This device has the noteworthy feature that the level determination functions according to the so-called magnetostrictive principle, i.e. according to a method which utilizes the transit time of ultrasonic pulses produced by magnetic fields.
SUMMARY OF THE INVENTION
The object of the invention is to provide a volume determination device permitting a particularly accurate determination of the volume in the case of minimum apparatus cost and whilst avoiding measurement errors caused by gas occlusion. In addition, a method is provided for the filling of a tank and for determining the filling level, which implement the advantages of the device according to the invention.
This object is achieved with a device according to claim
1
and a method according to claim
18
.
The device according to the invention is based on the prior art in that the device for separating gas and the tank form an integrated unit, that a filling level measuring device is substantially provided in the interior of the tank for determining the position of at least one boundary surface of the medium in the tank and that the filling level measuring device has at least one dipstick. This device renders unnecessary the use of a separate air separator, although this would not appear possible on the basis of the prior art, particularly in view of the aforementioned DIN 19217: 1997-11. Air separation initially takes place in the tank to be filled or the filled tank, which is possible in that the volume measurement determined by level measurement takes place in an extremely precise manner in the tank and not, as in the prior art, exclusively through a flowmeter upstream of the tank. This considerably reduces apparatus costs.
The device according to the invention is particularly advantageous if the filling level measuring device has a transsonar displacement transducer coupled to a computer operating according to the magnetostrictive principle and which is equipped with at least one dipstick and at least one float, the float or floats being equipped with at least one magnet. The magnetostrictive principle is based on the phenomenon that two intersecting magnetic fields cause a deformation of the metal in which they are focussed. If an exciting current pulse is supplied to the dipstick, this leads to an axially symmetrical exciting magnetic field with respect to said dipstick. This interacts with the intersecting magnetic fields of the float magnets, so that there is a brief deformation and a resulting ultrasonic pulse in the dipstick acting as a waveguide. Knowing the velocity of sound in the waveguide, conclusions can be drawn from the position of the magnets and consequently of the float from the transit time of the ultrasonic pulse through the dipstick up to a receiver preferably positioned terminally on the dipstick. Displacement transducers of this type are well known. As a result of the thus equipped device it is possible to measure the float position to an order of magnitude of 10 æ. In addition, transsonar displacement transducers are long term-stable and consequently fulfil the strict legal requirements concerning calibration and measuring accuracy.
It is advantageous for the dipstick to be fixed to the top of the tank. This permits an easy removal and fitting of the dipstick, which can e.g. be useful in connection with maintenance and cleaning.
It is particularly advantageous to provide a reference signal generator on the underside of the tank substantially on the dipstick axis and for the dipstick to penetrate the reference signal generator. The reference signal generator emits a filling level-independent signal, so that the receiver receives two generally successive signals. Through the measurement of the transmit times of both signals and subtraction it is possible to eliminate a measurement error as a result of the e.g. temperature-caused linear extension of the dipstick. Through the placing of the reference signal generator on the underside of the tank and the dipstick penetrating the same, the float can pass into the lower area of the tank and generate corresponding filling level signals. As a result of the free penetration of the reference signal generator, the dipstick is not prevented from any temperature-caused extension, so that this can occur without stressing the system.
It is also advantageous to fix the dipstick to the underside of the tank, particularly in view of possibly varying design possibilities.
The displacement transducer is
Barlian Reinhold
Boehm Alfred
Boehm Gerd
Bretzendorfer Johann
Brueggemann Alfons
Bartec Logistic Management GmbH
Jacobson & Holman PLLC
Shah Kamini
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