• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    In a density measuring device (1) for determining the density of a fluid (2), comprising a hollow body (5) arranged in an interior (3) of a container (4) for receiving the fluid (2), an exciter device (6) Excitation of a vibration of the hollow body (5) and a sensor device (7) for detecting the period of the oscillation of the hollow body (5), it is proposed that a temperature measuring device (8) is provided for measuring a temperature of a first region (9) of the hollow body ( 5), and that the interior (3) of the container (4) is evacuated.
    公开号:AT514574A4
    申请号:T8002013
    申请日:2013-10-17
    公开日:2015-02-15
    发明作者:Hans Dipl Ing Dr Stabinger；Helmut Dipl Ing Dr Heimel
    申请人:F Messtechnik Dr Hans Stabinger Gmbh Lab；
    IPC主号:
    专利说明:

    The invention relates to a density measuring device according to the preamble of claim 1.
    Such density measuring devices comprise a hollow body for determining the density of a fluid, therefore liquids, gases and mixtures of both, wherein the hollow body is filled with the fluid, the hollow body to a vibration in its natural frequency, or harmonic harmonics thereof is excited, the period of this oscillation determined and from this measured period of time the density of the fluid is calculated. Such density measuring devices are also known by the term measuring transducer or bending oscillator. The density determination can in this case be used, for example, to determine the concentration ratio of two liquids, for example water and ethanol.
    Since the density of the fluid also depends on its temperature, accurate density measuring devices have a temperature control device which keeps the entire density measuring device, together with the fluid to be measured, at a constant and known temperature. For this purpose, conventional density measuring devices have a tempering container, which is kept at a constant and known temperature. The hollow body is arranged in an inner space of the temperature-control container, wherein the inner space is filled with hydrogen for better heat transfer. Despite this optimized heat transfer, the temperature compensation needed for an accurate measurement takes up to five minutes.
    The disadvantage of this is that a precise measurement of the density takes a long time.
    The object of the invention is therefore to provide a density measuring device of the type mentioned above, with which the disadvantages mentioned can be avoided, and with which an accurate measurement of the density of the fluid can be faster.
    This is achieved by the features of claim 1 according to the invention.
    This has the advantage that the duration of a measurement can be significantly reduced, since no longer a temperature compensation of the entire
    Density device must wait, but only a much faster running temperature compensation between the fluid and the hollow body. Here, the hollow body with the fluid to be measured is thermally substantially decoupled from the remaining density measuring device by the vacuum in the interior, since a temperature compensation between the hollow body and the container takes place very slowly, and therefore the temperature of the hollow body and of the fluid are considered to be substantially constant over the duration of the measurement can. Thus, the need to bring large parts of the density measuring device to a known temperature is eliminated. As a result, there is no need to wait for a lengthy temperature compensation between the hollow body and the container, whereby the measurement of the density of the fluid can take place much faster.
    Furthermore, the invention relates to a method for determining the density of a fluid according to claim 8.
    The object of the invention is therefore further to provide a method for determining the density of a fluid, with which an accurate determination of the density can be made.
    The advantages of the method correspond to the advantages of the density measuring device.
    The subclaims relate to further advantageous embodiments of the invention.
    It is hereby expressly referred to the wording of the claims, whereby the claims at this point are incorporated by reference into the description and are considered to be reproduced verbatim.
    The invention will be further described with reference to the accompanying drawings, in which only preferred embodiments are shown by way of example. Showing:
    1 shows a first preferred embodiment of a density measuring device as a section in plan view;
    Fig. 2 is a side view of a second preferred embodiment of the density measuring device; and
    3 shows the second preferred embodiment of the density measuring device in plan view.
    FIGS. 1 to 3 show different embodiments of a density measuring device 1 for determining the density of a fluid 2, comprising a hollow body 5 arranged in an interior 3 of a container 4 for receiving the fluid 2, an excitation device 6 for exciting a vibration of the hollow body 5 and a sensor device 7 for detecting the period of oscillation of the hollow body 5. Such density measuring devices 1 are also known under the name of measuring oscillators or bending oscillators.
    The density measuring device 1 has a hollow body 5 for determining the density of a fluid 3, wherein the hollow body 5 may in particular be tubular, and more preferably may comprise a plurality of straight and substantially parallel tube sections 12. The straight pipe sections 5 can be connected by, in particular U-shaped, deflection sections 16. For the measurement, the hollow body 5 contains the fluid from which the density is to be determined. The fluid 5 may be liquids, gases and mixtures of liquids and / or gases.
    The hollow body 5 is arranged in an inner space 3 of a container 4, wherein the intended for vibration areas of the hollow body 5, in particular the straight pipe sections 12, are arranged freely in the interior space 3. The container 4 may in particular be gas-tight. The fluid 2 can preferably pass through a supply line 13 and / or discharge line 14 of the container 4 into the hollow body 5 and / or leave it. The measurement of the density of the fluid 2 can also take place when the hollow body 5 is traversed by the fluid 2 during the measuring process.
    The density measurement in the hollow body 5 filled with the fluid 2 to be measured is based on the fact that the natural frequency of such systems depends on the total mass, or mass of the hollow body 5 and the mass of the fluid 2 to be measured.
    For exciting a vibration of the hollow body 5, the density measuring device 1 has an exciter device 6, which may comprise, for example, a piezo element or a coil.
    In order to detect the frequency or the period of the oscillation of the hollow body 5, the density measuring device 1 has a sensor device 7, which may comprise, for example, a piezo element or a coil.
    In particular, the excitation device 6 and the sensor device 7 can be combined in a device which, both separately in time, excites the oscillation and measures the period duration.
    The characteristic of the oscillating system of hollow body 5 and fluid 2 can be measured in particular in the vicinity of its natural frequency, wherein the hollow body 5 is excited to vibrate by means of the excitation device 6, the oscillating system stabilizes after settling in the area of the natural frequency, and the sensor device 7 measures the period duration.
    It is provided that a temperature measuring device 8 is provided for measuring a temperature of a first region 9 of the hollow body 5, and that the inner space 3 of the container 4 is evacuated. The temperature measuring device 8 is part of the density measuring device 1, and adapted to measure the temperature of a first region 9 of the hollow body 5. In this case, it can be assumed that a temperature equalization has taken place between the fluid 5 and essentially the entire hollow body 5, for which reason it is sufficient to measure the temperature of the hollow body 5 at the first area 9. In order to increase the measurement accuracy of the temperature, or to check whether the temperature is the same over the entire hollow body 5, the temperature of the hollow body 5 can also be measured at other regions of the hollow body 5.
    The interior 3 of the container 4 is evacuated to prevent or at least significantly reduce heat transfer from the hollow body 5 to the container 4 via the gas in the interior, whether by convection or direct heat conduction. This effect is also known by the term vacuum thermal insulation. The advantage of the vacuum thermal insulation is further that a swinging motion of the hollow body 5 is not impaired.
    Particularly preferably, it can be provided that the pressure in the interior is less than 10,000 Pa, in particular less than 100 Pa, particularly preferably less than 0.1 Pa.
    In particular, it can be provided that in the interior 3 is a pressure in which the mean free path of the residual gas molecules is greater than the minimum distance of the oscillating regions of the hollow body 5, so in particular the straight pipe sections 12 of the hollow body 5, to a wall of the container 4th
    Furthermore, a method for determining the density of the fluid 2 is provided, the fluid 2 being introduced into the hollow body 5 arranged in the evacuated interior 3 of the container 4, the temperature of the first region 9 of the hollow body 5 being measured, in one measuring operation a vibration of the hollow body 5 is excited and the period of the vibration is detected, the density of the fluid 2 being determined on the basis of the period duration and the temperature of the first region 9 of the hollow body 5. Here, in the measuring operation, the temperature of the hollow body 5 is equal to the temperature of the fluid 2, whereby an accurate determination of the density of the fluid 2 is possible.
    This results in the advantage that the duration of a measurement can be significantly reduced, since no longer a temperature compensation of the entire density measuring device 1 must be awaited, but only a much faster running temperature compensation between the fluid 2 and the hollow body 5. Here, the hollow body 5 is to be measured Fluid 2 is thermally substantially decoupled from the remainder of the density measuring device 1 by the vacuum in the interior space 3, since temperature compensation between the hollow body 5 and the container 4 is very slow, and therefore the temperature of the hollow body 5 and the fluid 2 are considered substantially constant for the duration of the measurement can. Thus, there is no need to bring large parts of the density measuring device 1 to a known temperature. As a result, no lengthy temperature compensation must be awaited between the hollow body 5 and the container 4, as a result of which the measurement of the density of the fluid 2 can take place substantially more rapidly.
    In this case, it can be provided, in particular, that the measuring process takes place within one minute after the introduction of the fluid 2 into the hollow body 5.
    It can preferably be provided that the measurement of the temperature of the first region 9 is carried out before the measuring operation, since here no oscillation of the hollow body 5 disturbs the measurement of the temperature.
    Furthermore, it can be provided that the measurement of the temperature takes place during the measuring process of the oscillation.
    Particularly preferably, it can be provided that the temperature of the first region 9 deviates from a temperature of the container 4 in the measuring process. In other words, the measuring process is carried out at a time at which no temperature compensation between the container 4 and the hollow body 5 has taken place.
    The container 4 may be made of glass or metal in particular.
    Particularly preferably, the container 4 can be evacuated via a connection 15, which can then be sealed by melting. This can simply provide a particularly long-lasting vacuum.
    Alternatively it can be provided that the interior 3 is evacuated by means of a vacuum pump.
    The hollow body 5 may be made of glass or metal in particular.
    In particular, it can be provided that the interior 3 and / or the hollow body 5 are at least partially mirrored. In this case, in particular, an inner surface 19 of the inner space 3 facing the hollow body 5 and / or an outer surface 20 of the hollow body 5 facing the inner space 3 can be at least partially mirrored. The heat transfer by means of radiation can be reduced by the at least partially mirrored surfaces, whereby the thermal insulation of the hollow body 5 with respect to the container 4 can be further improved.
    Particularly preferably, it can be provided that the hollow body 5 is formed such that when an excited vibration, a center of mass of the hollow body 5 is static, so is not moved. Thereby, the density measuring device 1 can be made lightweight and compact since there is no
    Counterweight is necessary to accommodate the swinging motion of the hollow body 5, since the center of mass of the hollow body 5 remains static in the vibration.
    The hollow body 5 can be particularly preferably designed such that the straight pipe sections 12 oscillate in opposite directions. Such arrangements are also referred to as X-swingers.
    Particularly preferably, it can be provided that the first region 9 is arranged in a vibration node of the hollow body 5. The vibration node of the hollow body 5 is in this case a region of the hollow body 5 which is static in the case of the excited oscillation, that is to say it remains at the same point. This results in the advantage that the oscillation process and the temperature measurement do not influence each other or at least only slightly. The vibration node may, in particular, be a deflection section 16 of the hollow body 5.
    Furthermore, it can be provided that the first region 9 - viewed along the course of the hollow body 5 - is arranged centrally. In other words, the first region 9 may be disposed substantially midway between the lead 13 and the lead 14.
    In particular, it may be provided that the hollow body 5 is substantially tubular, and that in a majority of the hollow body 5, a wall thickness of the hollow body 5 is smaller than 10% of a diameter of the hollow body 5. The hollow body 5 may be formed thin-walled in other words. Thereby there is the advantage that a temperature of the hollow body 5 can adapt to the temperature of the fluid 2 quickly and rapidly, whereby a temperature compensation between the hollow body 5 and the fluid 2 takes place rapidly. Hereinafter, substantially immediately after the introduction of the fluid 2, the measurement of the temperature of the fluid can already be made Be carried hollow body 5, since this is very quickly in temperature equilibrium with the fluid 2.
    Furthermore, it can be provided that the hollow body 5 in a second region 21, on which the hollow body 5 is integrally formed on the container 4, is formed reinforced. Thereby, the vibration in the second region 21, at which there may be an increased heat transfer, can be kept low, whereby the second region 21 has a negligible influence on the period of the oscillation.
    Particularly preferably, it can be provided that the temperature measuring device 8 has a temperature sensor 10, and that the temperature sensor 10 is mounted in the first region 9 on the hollow body 5. The temperature measuring device 8 can hereby be designed in particular as a contact thermometer. The temperature sensor 10 is a sensor which is thermally in contact with the hollow body and assumes the temperature of the hollow body 5 in the first region 9. The temperature sensor 10 may be, for example, a bimetallic sensor, which causes an electrical voltage by means of Seebeck or thermal effect. However, a variety of other modes of operation of a temperature sensor 10 are also known to those skilled in the art. Such a temperature measuring device 8 offers the advantage that it measures the temperature of the first region 9 very quickly and reliably.
    In particular, the temperature sensor 10 can output its voltage by means of a line pair 17, wherein the line pair can be led out of the container 4 in particular by means of a vacuum feed-through 18.
    Furthermore, it can be provided that the temperature measuring device 8 comprises a radiation thermometer which is directed onto the first region 9.
    The temperature measuring device 8 can in this case be designed in particular as a non-contact thermometer. Such a radiation thermometer may, for example, be a pyrometer which determines from the electromagnetic radiation of the first region 9 its temperature.
    The temperature measuring device 8 may also comprise a thermal camera which can detect the temperature distribution of the hollow body 5 two-dimensionally. For example, the thermal camera may be used to ensure that the temperature is evenly distributed over the entire oscillating hollow body 5.
    Particularly preferably, it can be provided that at least the sensor device 7 and the temperature measuring device 8 are connected to an evaluation unit 11, and that the evaluation unit 11 is designed to determine the density of the fluid 2 on the basis of the period duration and the measured temperature of the hollow body 5. Furthermore, it can be provided that the evaluation unit 11 is designed as a digital circuit device. Thereby, the entire evaluation of the density of the fluid 2 can be made in a particularly simple and reliable manner, wherein the temperature of the first area 9 can be easily taken into account.
    The evaluation unit 11 can determine the density on the basis of the period of the excited vibration of the hollow body 5 in a known manner, wherein the temperature of the first region 9 of the hollow body 5, which can be assumed as the temperature for the total oscillating system, is taken into account. The density of the fluid 2 can be output by the evaluation unit 11 after the calculation, for example via a display or an electronic interface.
    Furthermore, the exciter device 6 can also be connected to the evaluation unit 11. In this case, it can preferably be provided that the excitation signal, with which the exciter device 6 is operated, lies on the input side of the evaluation unit 11. As a result, when determining the density of the fluid 2, the evaluation unit 11 can take into account the exciter signal, in particular its frequency, whereby an accurate measurement result can be achieved.
    1 shows a first preferred embodiment of the density measuring device 1, in which the hollow body 5 comprises two parallel pipe sections 12, which are connected by means of a deflection section 16. The hollow body 5 is in this case substantially U-shaped. The temperature measuring device 8 measures the temperature of the deflection section 16. The excitation device 6 and the sensor device 7 are not shown here, wherein the excited oscillation of the two tube sections 12 is indicated by arrows.
    FIGS. 2 and 3 show a second preferred embodiment of the density measuring device 1, in which the hollow body 5 comprises four parallel tube sections 12, which are connected by means of a total of three deflection sections 16. Here, the hollow body 5, as indicated in Fig. 3, be excited like a tuning fork. The temperature measuring device 8 measures the
    Temperature of a central deflection section 16. The excitation device 6 and the sensor device 7 in this case comprise electromagnetic coils, which are arranged outside the interior space 3, and two permanent magnets fixed to the hollow body 5, which are each arranged in a deflection section 16 facing away from the supply line 13. The exciter device 6 and the sensor device 7 are shown only partially in FIG. Further, the line pair 17 and the vacuum feedthrough 18 are not shown in FIG.
    claims:
    权利要求:
    Claims (9)
    [1]
    1. Density measuring device (1) for determining the density of a fluid (2), comprising a hollow body (5) arranged in an interior (3) of a container (4) for receiving the fluid (2), an excitation device (6) for exciting a vibration of the hollow body (5) and a sensor device (7) for detecting the period of the oscillation of the hollow body (5), characterized in that a temperature measuring device (8) is provided for measuring a temperature of a first region (9) of the hollow body (5), and that the interior (3) of the container (4) is evacuated.
    [2]
    2. Density measuring device (1) according to claim 1, characterized in that the first region (9) is arranged in a vibration node of the hollow body (5).
    [3]
    3. Density measuring device (1) according to claim 1 or 2, characterized in that the temperature measuring device (8) has a temperature sensor (10), and that the temperature sensor (10) in the first region (9) on the hollow body (5) is mounted.
    [4]
    4. Density measuring device (1) according to one of claims 1 to 3, characterized in that the temperature measuring device (8) comprises a radiation thermometer, which is directed to the first region (9).
    [5]
    5. density measuring device (1) according to one of claims 1 to 4, characterized in that the interior (3) and / or the hollow body (5) are at least partially mirrored.
    [6]
    6. density measuring device (1) according to one of claims 1 to 5, characterized in that at least the sensor device (7) and the temperature measuring device (8) are connected to an evaluation unit (11), and that the evaluation unit (11) is formed, based on the period and the measured temperature of the hollow body (5) to determine the density of the fluid (2).
    [7]
    7. Density measuring device (1) according to one of claims 1 to 5, characterized in that the hollow body (5) is substantially tubular, and that in a large part of the hollow body (5) has a wall thickness of the hollow body (5) is less than 10% of a diameter of Hollow body (5).
    [8]
    8. Method for determining the density of a fluid (2), wherein the fluid (2) is introduced into a hollow body (5) arranged in an evacuated interior (3) of a container (4), wherein a temperature of a first region ( 9) of the hollow body (5) is measured, wherein in a measuring operation a vibration of the hollow body (5) is excited and the period of oscillation is detected, the density of the fluid (2) based on the period and the temperature of the first portion (9) of the hollow body (5) is determined.
    [9]
    A method according to claim 8, characterized in that in the measuring operation the temperature of the first region (9) deviates from a temperature of the container (4).
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    同族专利:
    公开号 | 公开日
    AT514574B1|2015-02-15|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    AT353039B|1976-11-29|1979-10-25|Kratky Otto Dipl Ing Dr Dr H C|DEVICE FOR MEASURING DENSITY|
    DE3609489A1|1986-02-24|1987-08-27|Hatschek Rudolf A|DEVICE FOR DETERMINING THE DENSITY|
    US4838084A|1988-08-30|1989-06-13|Hans Leopold|Density measuring instrument|
    DE102005044927B3|2005-09-20|2007-03-15|Seppeler-Stiftung für Flug- und Fahrwesen|Liquid e.g. fuel, density measuring device for engine test bed, has sack tubes that are supported at support unit, where support unit comprises large inertia mass in comparison to mass of sack tubes and mass of received fluid|WO2017005243A1|2015-07-03|2017-01-12|Schmidt & Haensch Gmbh & Co.|Method and device for determining the density of liquids|
    WO2020223749A1|2019-05-03|2020-11-12|Anton Paar Gmbh|Method for checking the state of a temperature sensor of a density sensor|
    AT520318B1|2017-11-06|2019-03-15|Mettler Toledo Gmbh|Density measuring device for determining the density of fluid media|
    AT522941A1|2019-09-12|2021-03-15|Wolfgang Belitsch|Oscillator for density measurement of a liquid|
    法律状态:
    2018-12-15| PC| Change of the owner|Owner name: METTLER-TOLEDO GMBH, CH Effective date: 20181016 |
    优先权:
    申请号 | 申请日 | 专利标题
    AT8002013A|AT514574B1|2013-10-17|2013-10-17|Density measurement device|AT8002013A| AT514574B1|2013-10-17|2013-10-17|Density measurement device|
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