DE19618442A1 - Fluid flow measuring device using hot conductor exposed to fluid temp - Google Patents

Fluid flow measuring device using hot conductor exposed to fluid temp

Info

Publication number
DE19618442A1
DE19618442A1 DE1996118442 DE19618442A DE19618442A1 DE 19618442 A1 DE19618442 A1 DE 19618442A1 DE 1996118442 DE1996118442 DE 1996118442 DE 19618442 A DE19618442 A DE 19618442A DE 19618442 A1 DE19618442 A1 DE 19618442A1
Authority
DE
Germany
Prior art keywords
fluid
temperature
thermistor element
voltage drop
value
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
DE1996118442
Other languages
German (de)
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
MUELLER FRIEDRICH 74670 FORCHTENBERG DE
Original Assignee
MUELLER FRIEDRICH 74670 FORCHTENBERG DE
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by MUELLER FRIEDRICH 74670 FORCHTENBERG DE filed Critical MUELLER FRIEDRICH 74670 FORCHTENBERG DE
Priority to DE1996118442 priority Critical patent/DE19618442A1/en
Publication of DE19618442A1 publication Critical patent/DE19618442A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01FMEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through the meter in a continuous flow
    • G01F1/68Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through the meter in a continuous flow by using thermal effects
    • G01F1/696Circuits therefor, e.g. constant-current flow meters
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01FMEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through the meter in a continuous flow
    • G01F1/68Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through the meter in a continuous flow by using thermal effects
    • G01F1/684Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01PMEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P13/00Indicating or recording presence, absence, or direction, of movement
    • G01P13/0006Indicating or recording presence, absence, or direction, of movement of fluids or of granulous or powder-like substances
    • G01P13/006Indicating or recording presence, absence, or direction, of movement of fluids or of granulous or powder-like substances by using thermal variables

Abstract

The system for establishing the flow of a fluid, has a hot conductor element (5), which can be arranged in such a way, that it is exposed to the temp. of the fluid. A constant current source (12) is connectable with the hot conductor element, and is designed for delivering a constant current to this. A voltmeter (13) measures the voltage drop across the hot conductor element. In addition a comparator (14) is provided, which compares the measured voltage drop with a stored comparison value. With an establishing of a deviation between the two values, an indicator is activated. The stored comparison value is dependent on the temp. of the fluid.

Description

The invention is based on a method and a device device for determining the flow of a fluid.

It is known to determine whether a fluid, for example a liquid flowing in a pipe in the pipe a mechanical element driven by the flow to arrange. This is not the case with aggressive media Possibility in many cases.

The invention has for its object a possibility create without moving parts to determine whether a Fluid flows in a line or not. The possibility should be applicable to different media.

To achieve this object, the invention proposes a Vorrich device with the features of claim 1 and a method with the features of claim 10. Further training of the Invention are the subject of the respective dependent claims che.  

The device according to the invention works as follows. The thermistor element, i.e. an element with a negative Temperature coefficient, is arranged so that it for example immersed in the liquid to be measured. This is achieved by applying constant current Thermistor element a temperature that is slightly above the tempe rature of the fluid. With this loading with constant current, a voltage drop occurs, which is a measure for this temperature of the thermistor element. As soon as now the fluid sets in motion, the heat from that Thermistor element led away, resulting in a change in Temperature of the thermistor element and thus to a change voltage drop across the thermistor element. From the comparison of the voltage drop with the comparison can therefore value the occurrence of the flow of the fluid be closed so that an indicator can be operated. Conversely, if the flow of the fluid stops, that of the heat dissipated heat no longer dissipated, so that the original state returns, so that the display can be switched off again. Of course you can also a change display can be used, in which the Flow and standing of the fluid are shown differently becomes.

The stored comparison value is from the temperature of the Fluid dependent. If the device and method for the use is intended for a liquid made up of always has the same temperature for certain reasons, so can the comparison value when installing the device can be set once.

If the checking fluid has no fixed temperature, it can according to the invention a calibration device to take into account the Temperature of the fluid can be provided.  

This calibration device can then in any way take into account the actual temperature of the fluid.

One possibility is that the calibration device in Depends on the temperature of the fluid for comparison used stored value changes.

In particular, it can be provided that depending on the temperature of the calibration device a certain Ver reads equivalent value from a table and for comparison selects. The assignment between the comparative value and the Temperature is once when the device is manufactured given. It is also possible to use them because of to constantly change measurements over time.

So that the device can work continuously be provided to be one of the temperature of the fluid exposed temperature sensor. This can continuously Measure the temperature of the fluid.

The temperature sensor can preferably be arranged in this way be that he is near the thermistor element is arranged, but so far from this, that that of temperature measured by him from the overheating temperature of the Thermistor is not affected.

According to the invention it can be provided that the temperature ler and / or the thermistor element in a screw nipple are arranged, which is in a threaded bore one of the fluid flowing through line can be screwed. The Screw nipples or the screw-in depth can be adjusted in this way be that the temperature sensor or the thermistor element protrude straight into the interior of the line so that the  Flow cross section is practically not changed, other but the real temperature of the fluid is measured.

In particular, it can be provided that the different Evaluations, comparisons, saving, etc. with the help a microprocessor.

Further characteristics, details and advantages result from the claims, the wording of which by reference to Content of the description is made of the following description exercise of a preferred embodiment of the invention as well based on the drawing. Here show:

Figure 1 shows schematically an arrangement of a thermistor element and a temperature sensor in a pipeline.

Fig. 2 in an enlarged scale an illustration of a screw containing the thermistor element screw nipple.

In Fig. 1 a conduit 1 member depicted schematically flows through which in operation a liquid. With the aid of the device proposed by the invention, it should now be determined whether this liquid flows or is at a standstill for some reason. At the point where the flow is to be determined, the line contains two bores, which are threaded, for example. The holes are arranged in the longitudinal direction of the line 1 at the same point, but have a distance of a quarter arc in the circumferential direction. A screw nipple 2 , 3 is screwed into each bore. In one screw nipple 2 , a temperature sensor 4 indicated by dashed lines is arranged. The temperature sensor is arranged and designed so that it can measure the temperature of the fluid present in line 1 .

A thermistor element 5 is arranged in the second screw nipple 3 , which protrudes somewhat into the interior of the line 1 . This thermistor element 5 is therefore also exposed to the temperature of the fluid in line 1 .

To screw in the screw nipples 2 , 3 each contain a hexagon socket 6 , on which one can attack with a wrench.

Of the thermistor element 5 make two electrical wires 7, 8 to an evaluation and display unit. 9

The unit 9 is also connected to the temperature sensor 4 by two lines 10 , 11 .

In the evaluation and display unit 9 , a constant current source 12 is arranged which, with the aid of an electrical supply voltage, for example the household network, places a current of constant magnitude via the two lines 7 , 8 on the thermistor 5 .

A voltage measuring device 13 is also provided in the unit 9 , which measures the voltage drop across the thermistor 5 .

The unit also contains a comparator 14 and a table memory 15 .

The display and evaluation unit 9 contains further control devices, which can be implemented, for example, with the aid of a program running on a microprocessor.

The display and evaluation unit 9 controls an optical display 15 in the example shown, which can be a light-emitting diode or a plurality of light-emitting diodes.

The operation of the device shown in Fig. 1 is as follows. With the help of the temperature sensor 4 , the tempera ture of the liquid or the medium whose currents are to be checked is measured. On the basis of the measured temperature value, the display and evaluation unit 9 selects a comparison value assigned to this temperature from the table 15 .

A current of constant value is passed through the thermistor 5 with the aid of the constant current source 12 . As a result, the thermistor 5 heats up to a temperature which is somewhat higher than the temperature of the medium surrounding it. The thermistor 5 has a resistance value, which leads to a voltage drop, which is measured with the aid of the voltmeter 13 . The comparator 14 compares the measured voltage drop with the comparison value read from the table 15 .

When the medium is at a standstill, the thermistor 5 has a certain temperature and thus a certain voltage drop. If a flow of liquid now occurs, the heat is removed from the surroundings of the thermistor 5 , so that the temperature of the thermistor 5 lowers somewhat. This leads to a change in the voltage drop. The change in the voltage drop 14 is determined by the comparator 14 in the comparison with the comparison value. If there is a deviation, the display 15 is actuated by the unit 9 .

Since the desired normal case when monitoring the flow of a liquid is the flow state and not the standstill, the display 15 is switched off whenever a flow is detected. If the values to be compared differ, pressing the display means switching off. Of course, a switchover can also be carried out so that a different type of display takes place in the normal state than in the fault state. For example, a red light-emitting diode could light up when the liquid is at a standstill, while in the flow state either no display or a green light-emitting diode is switched on.

Due to the consideration of the temperature with the help of the temperature sensor 4 by selecting a different comparison value from the table 15 , the device also works with changing temperatures of the liquid to be monitored.

The device contains no moving and therefore wearing parts and does not require any storage. Both the temperature sensor 4 and the heating conductor 5 can be shielded from aggressive media without the sensitivity being impaired.

Fig. 2 shows a section through the screw nipple. 3 The screw nipple 3 has on the side of the hexagon socket 6 facing the line 1 a sleeve part provided with an external thread 17 , in which the thermistor element 5 is inserted. In the example shown, it protrudes in a hemispherical shape over the free end of the sleeve.

Between the external thread 17 and the hexagon socket 6 , a recess 18 is provided, into which an O-ring can be inserted. This serves as a seal when screwing in the screw nipple.

On the side facing away from the thermistor 5 , the screw nipple contains a screw attachment 19 through which the lines 7 , 8 can be passed. For example, one of the lines 7 , 8 receiving the tubular casing can be screwed on.

The device can also be subsequently monitored be attached to the lines. It is only necessary for this Lich, drill two holes in the line and with one Thread.

The circumferential distance between the two screw nipples and thus the temperature sensor 4 from the thermistor element 5 is selected so that the temperature of the thermistor element 5 , which is somewhat higher than the surrounding fluid, does not lead to an incorrect temperature display of the temperature sensor 4 .

According to the invention it can be provided that the value of the constant current flowing through the thermistor element 5 is set as a function of the temperature of the fluid. If the device is used to monitor the flow of a liquid which is always at the same temperature, this value can be set once. When monitoring fluids with changing temperatures, it can be provided according to the invention that the value of this current is then changed as a function of the temperature. Nevertheless, it is a constant current because the device sends a constant current through the thermistor element at a certain temperature. By adapting the value of the constant current to the temperature, either the measured or the set one, it becomes possible to optimize the response time. The value of the constant current can be selected so that the cheapest constant current is used for each temperature.

To carry out this step, the Vorrich appropriate means for changing the value of the constant current. This facility can be in of the constant current source mentioned.

Claims (15)

1. Device for determining the flow of a fluid with
  • 1.1 a thermistor element ( 5 ), the
  • 1.1.1 can be arranged so that it is exposed to the temperature of the fluid,
  • 1.2 a constant current source ( 12 ), the
  • 1.2.1 connectable to the thermistor element ( 5 ) and
  • 1.2.2 is designed to deliver a constant current to it,
  • 1.3 a voltmeter ( 13 ), the
  • 1.3.1 is designed to measure the voltage drop across the Heißlei terelement ( 5 ), and with
  • 1.4 a comparator ( 14 ) which
  • 1.4.1 is designed to compare the measured voltage drop with a stored comparison value and
  • 1.4.2 if a discrepancy between the two values is determined, an indicator is actuated.
2. Device according to claim 1, wherein the stored  Comparison value depends on the temperature of the fluid is.
3. Device according to claim 1 or 2, with an calibration direction to take into account the temperature of the Fluids.
4. The device according to claim 3, wherein the calibration device depending on the temperature of the fluid to the Comparison used stored value changes.
5. Apparatus according to claim 3 or 4, wherein the calibration direction depending on the temperature of the fluid from a table a comparison value from a lot number of comparison values.
6. Device according to one of the preceding claims, with a temperature sensor exposed to the temperature of the fluid ( 4 ).
7. The device according to claim 6, in which the temperature sensor ( 4 ) in the region of the thermistor element ( 5 ) is arranged such that the temperature of the Heißleiterelemen tes ( 5 ) does not affect the temperature sensor ( 4 ) in its temperature.
8. Apparatus according to claim 6 or 7, in which the temperature sensor ( 4 ) and / or the thermistor element ( 5 ) are each arranged in a screw nipple ( 2 , 3 ) which can be screwed into a threaded bore of a line ( 1 ) through which the fluid flows is.
9. Device according to one of the preceding claims, at  which compares and evaluates using a Microprocessor can be performed.
10. A method of determining fluid flow in which
  • 10.1 a thermistor element ( 5 ) is exposed to the temperature of the fluid,
  • 10.2 a current of constant value flows through the thermistor element ( 5 ),
  • 10.3 the voltage drop across the thermistor element ( 5 ) is measured,
  • 10.4 the measured voltage drop is compared with a stored comparison value, and
  • 10.5 if the two values differ from each other, an indicator is actuated.
11. The method of claim 10, wherein the comparison value changed depending on the temperature of the fluid becomes.
12. The method of claim 10 or 11, wherein the tempe rature of the fluid is measured.
13. The method according to claim 12, wherein the temperature of the fluid is measured at a point which is in the vicinity of the thermistor element ( 5 ), but is so far from this that the current-carrying thermistor element ( 5 ) the temperature sensor ( 4 ) unaffected.
14. The method according to any one of claims 10 to 13, wherein the value of the current flowing through the thermistor element ( 5 ) is changed depending on the temperature of the fluid.
15. The method according to claim 10 to 14, wherein the comparison and evaluations with the help of a microprocessor be performed.
DE1996118442 1996-05-08 1996-05-08 Fluid flow measuring device using hot conductor exposed to fluid temp Withdrawn DE19618442A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE1996118442 DE19618442A1 (en) 1996-05-08 1996-05-08 Fluid flow measuring device using hot conductor exposed to fluid temp

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE1996118442 DE19618442A1 (en) 1996-05-08 1996-05-08 Fluid flow measuring device using hot conductor exposed to fluid temp

Publications (1)

Publication Number Publication Date
DE19618442A1 true DE19618442A1 (en) 1997-11-13

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Family Applications (1)

Application Number Title Priority Date Filing Date
DE1996118442 Withdrawn DE19618442A1 (en) 1996-05-08 1996-05-08 Fluid flow measuring device using hot conductor exposed to fluid temp

Country Status (1)

Country Link
DE (1) DE19618442A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102008002871A1 (en) * 2008-05-29 2009-12-24 Postberg + Co. Druckluft-Controlling Gmbh Measuring arrangement for measuring e.g. mass flow rate of compresses air, has sensor arrangement located in sleeve, where lateral surface of sleeve is closed in flow direction viewed from side and provided with opening on opposite side

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2328247A1 (en) * 1972-07-27 1974-04-04 Polygraph Leipzig threshold
GB2045942A (en) * 1979-02-09 1980-11-05 Techne Cambridge Ltd Establishing maximum heat transfer within a fluidised bed
US4480467A (en) * 1982-11-29 1984-11-06 Hyperion, Inc. Flow monitoring device
DE3424642A1 (en) * 1983-07-11 1985-01-31 Gen Motors Corp Solid air flow probe
US5072614A (en) * 1989-03-10 1991-12-17 Yamatake-Honeywell Co., Ltd. Temperature compensating circuit
DE4130099A1 (en) * 1991-09-11 1993-03-25 Auergesellschaft Gmbh Gas detector
DE9217348U1 (en) * 1992-12-18 1993-04-08 Hiss, Eckart, Dr., 2300 Kiel, De
DE9406603U1 (en) * 1994-04-20 1994-08-04 Hiss Eckart Sensor

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2328247A1 (en) * 1972-07-27 1974-04-04 Polygraph Leipzig threshold
GB2045942A (en) * 1979-02-09 1980-11-05 Techne Cambridge Ltd Establishing maximum heat transfer within a fluidised bed
US4480467A (en) * 1982-11-29 1984-11-06 Hyperion, Inc. Flow monitoring device
DE3424642A1 (en) * 1983-07-11 1985-01-31 Gen Motors Corp Solid air flow probe
US5072614A (en) * 1989-03-10 1991-12-17 Yamatake-Honeywell Co., Ltd. Temperature compensating circuit
DE4130099A1 (en) * 1991-09-11 1993-03-25 Auergesellschaft Gmbh Gas detector
DE9217348U1 (en) * 1992-12-18 1993-04-08 Hiss, Eckart, Dr., 2300 Kiel, De
DE9406603U1 (en) * 1994-04-20 1994-08-04 Hiss Eckart Sensor

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
ALFORD,J.A.,et.al.: Combined Air Flow and Temperature Detector. In: IBM Technical Disclo- sure Bulletin,Vol. 19, No. 3, Aug. 1976, S.1101- S.1102 *
JP 6-117899 A., In: Patents Abstracts of Japan, P-1776, July 26,1994, Vol.18,No.399 *
STRICKERT,Herbert: Hitzdraht- und Hitzfilmane- mometrie, VEB-Verlag Technik, Berlin, 1974, S.20,21,85,86 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102008002871A1 (en) * 2008-05-29 2009-12-24 Postberg + Co. Druckluft-Controlling Gmbh Measuring arrangement for measuring e.g. mass flow rate of compresses air, has sensor arrangement located in sleeve, where lateral surface of sleeve is closed in flow direction viewed from side and provided with opening on opposite side
DE102008002871B4 (en) * 2008-05-29 2010-02-18 Postberg + Co. Druckluft-Controlling Gmbh Measuring arrangement

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