EP0922202A1 - Device for measuring hydraulic discharge volumes and leakages in a test piece - Google Patents

Device for measuring hydraulic discharge volumes and leakages in a test piece

Info

Publication number
EP0922202A1
EP0922202A1 EP97949961A EP97949961A EP0922202A1 EP 0922202 A1 EP0922202 A1 EP 0922202A1 EP 97949961 A EP97949961 A EP 97949961A EP 97949961 A EP97949961 A EP 97949961A EP 0922202 A1 EP0922202 A1 EP 0922202A1
Authority
EP
European Patent Office
Prior art keywords
measuring
medium
measuring section
test specimen
inlet
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Withdrawn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
EP97949961A
Other languages
German (de)
French (fr)
Inventor
Eberhard SCHÖFFEL
Klaus Kropf
Josef Ernst
Josef Seidel
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.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
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 Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of EP0922202A1 publication Critical patent/EP0922202A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/26—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M65/00—Testing fuel-injection apparatus, e.g. testing injection timing ; Cleaning of fuel-injection apparatus
    • F02M65/001—Measuring fuel delivery of a fuel injector
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/007—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring the level variations of storage tanks relative to the time
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/26—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields
    • G01F23/263—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields by measuring variations in capacitance of capacitors
    • G01F23/268—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields by measuring variations in capacitance of capacitors mounting arrangements of probes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F25/00—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume
    • G01F25/0092—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume for metering by volume
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M3/00—Investigating fluid-tightness of structures
    • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
    • G01M3/26—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors

Definitions

  • the invention relates to a device for measuring hydraulic flow rates and leaks on a test specimen, comprising a measuring section designed as an approximately vertical supply line to the test specimen and a capacitive sensor arranged in the measuring section, which detects both at least one measuring medium and at least one medium can be acted upon to generate a pressure (pressure medium) acting on the measuring medium.
  • Such a device is shown for example from DE 42 05 453 AI.
  • the measuring section is connected to the test object via a branch in which a valve is arranged.
  • the problem with this device is that flow and leakage measurements are only possible with limited accuracy, because of the branching and in particular through the valve arranged in the branching, errors can occur, for example due to leaks in this valve, which falsify the measurement result.
  • the invention is therefore based on the object of improving a device for measuring hydraulic flow rates and leakages on a test specimen of the generic type in such a way that precise measurements of flow rates and leakages are possible in a technically simple manner.
  • This object is achieved according to the invention in a device for measuring hydraulic flow rates and leaks on a test specimen of the type described in the introduction in that the test specimen is coupled directly to the measuring section.
  • the direct coupling of the test object to the test section has the great advantage that, on the one hand, a very precise measurement is possible and, on the other hand, that the measurement results cannot be falsified, which can be caused, for example, by leaky valves which are arranged between the test object and the test section .
  • the direct coupling of the test specimen to the test section also enables very fast measurements, since, for example, through branches arranged between the test specimen and the test section, Valves and the like caused measuring delays falsifying the measurement result are excluded.
  • An advantageous embodiment provides that the inlet / outlet for the pressure medium and the inlet / outlet for the measuring medium are arranged on a side of the measuring section facing away from the test object.
  • this arrangement permits a compact construction of the entire measuring device, on the other hand, high-precision measurements, since in addition to the measuring section and the test object, no further units are arranged in the test circuit.
  • Another advantageous exemplary embodiment provides that the inlet / outlet for the pressure medium are arranged on the side of the measuring section facing away from the test object and that the inlet / outlet for the measuring medium are arranged on the test object on the side thereof facing away from the measuring section.
  • Such an embodiment allows a particularly simple measurement of hydraulic flow rates and leaks on the discharge side (low pressure side) of the test object. It is independent of the operating pressure of the test object and can therefore be used up to any high pressure.
  • a swirling element is arranged between the inlet (the high-pressure side) of the test object and the measuring section for generating a rotating flow in the test object is.
  • the swirling element is a cylindrical disc with openings inclined in the axial and azimuthal direction.
  • Such a swirling element is on the one hand particularly easy to produce and on the other hand produces particularly effective three-way flows in the test specimen.
  • Shut-off valves are preferably arranged in the inlet and outlet feed lines of the medium supply.
  • the measuring section has the shape of a cylinder and that the capacitive sensor is a cylinder capacitor.
  • the capacitive sensor which is arranged as a cylindrical capacitor in the measuring section formed as a cylinder, can be acted upon in a particularly simple manner by the measuring medium and the pressure medium, since the measuring section and capacitive sensor "coincide" to a certain extent.
  • a wide variety of fluids can be used as the measuring medium and as the pressure medium.
  • the measuring medium is a hydraulic fluid and that the pressure medium is air.
  • the measuring medium and the pressure medium are each two immiscible liquids.
  • one of the electrodes of the capacitive sensor is provided with an electrically insulating coating.
  • FIG. 1 shows a first exemplary embodiment of a device according to the invention for measuring hydraulic flow rates and leaks on a test specimen
  • Fig. 2 shows a second embodiment of a device according to the invention for measuring hydraulic flow rates and leaks on a test specimen
  • FIGS. 1 and 2 show a basic circuit diagram of an evaluation circuit which can be used in the devices according to the invention for measuring hydraulic flow rates and leaks shown in FIGS. 1 and 2.
  • An exemplary embodiment of a device for measuring hydraulic flow rates and leaks on a test object 10, for example an injection valve used in automotive technology, shown in FIG. 1, comprises a measuring section 20 designed as an approximately vertical supply line to the test object 10 and one in the measuring section 20 arranged capacitive sensor 30 in the form of a cylindrical capacitor, the outer cylinder 31 coincides with the outer tube of the measuring section 20 and the central conductor 33 is arranged centrally in the outer cylinder 31 and thus the outer tube of the measuring section 20.
  • test specimen 10 is coupled directly to the measuring section 20 via a sealing element 12.
  • An electrically insulated, perforated central conductor fastening 35 is provided on the side of the capacitive sensor 30 facing the test object 10.
  • the center conductor 33 is guided to the evaluation circuit via an electrically insulating, pressure-tight bushing 36.
  • an inlet / outlet 40 is provided for a measuring medium 50, via which the measuring medium 20 and thus the capacitive sensor 30 in the form of the cylindrical capacitor can be acted upon with the measuring medium 50.
  • the inlet / outlet 40 of the measuring medium 50 can be closed via a first valve 41 and a second relief or return valve 42.
  • an inlet / outlet 60 is provided on the side of the measuring section 20 facing away from the test specimen 10, via which an inlet / outlet 60 is provided in the measuring section 20 for generating a pressure acting on the measuring medium 50, i.e. a print medium 70, can be fed.
  • the inlet / outlet 60 for the pressure medium 70 can be closed via a valve 61.
  • a pressure gauge 64 for measuring the pressure prevailing in the measuring section 20 can be provided downstream of the valve 61 in the inlet / outlet 60 for the pressure medium 70.
  • a swirling element 80 for generating a rotary flow in the test specimen 10 is also arranged between the test specimen 10 and the measuring section 20 and thus the capacitive sensor 30.
  • This rotary flow rinses out bubbles or the like, in particular, which may arise when the test sample 10 is exposed to the measuring medium 50, from the measuring medium 50 and the test sample 10.
  • the swirling element has the shape a cylindrical disk with openings (not shown) arranged inclined in the axial and azimuthal direction.
  • a hydraulic fluid is preferably used as the measuring medium and air as the pressure medium.
  • the center conductor 33 has a diameter of approximately 0.5 mm, whereas the outer cylinder 30 has a diameter of approximately 2 mm.
  • the length of the cylindrical capacitor is approximately 100 mm.
  • the center conductor 33 is provided with a thin, homogeneous, electrically insulating coating 34.
  • Such a device is particularly advantageous in particular for the measurement of low flow rates, since only the sealing element 12 for coupling the test specimen is located in the test circuit and, to that extent, no faults can arise, for example due to leakage of units arranged between the measuring section 20 and the test specimen 10 are, could arise.
  • the measuring medium 50 is first introduced into the measuring section 20 and the test object 10 via the inlet / outlet 40 with the valve 41 open and the valves 42, 61 closed.
  • the device under test 10 is opened and closed in a pulsed manner via a control line 11 for rinsing.
  • the entire measuring section 20 and the test specimen 10 are flooded with the measuring medium 50.
  • the valves 61 and 42 are then opened and the upper region of the measuring section 20 is blown out and dried by blowing in an air stream, ie the pressure medium 70.
  • the outlet bore of the inlet / outlet 40 of the measuring medium 50 is arranged below the inlet / outlet bore of the inlet / outlet 60 of the pressure medium, so that any measuring medium 50 present in the measuring section 20 can run out via the inlet / outlet 40 for the measuring medium 50.
  • valves 41, 42 in the inlet / outlet 40 of the measuring medium 50 are closed, while the valve 61 in the inlet / outlet 60 of the pressure medium 70 is open.
  • the test section 20 and the capacitive sensor 30 are subjected to a test pressure p, which can be detected by the manometer 64.
  • the level of the measuring medium 50 is detected by the capacitive sensor 30 and passed on to an evaluation circuit to be described in more detail below.
  • the device under test 10 is then opened in a controlled manner via a control line 11 and the level of the measuring medium 50 is detected again by the capacitive sensor 30.
  • the change in level in the measuring section 20 and thus in the capacitive sensor 30 in the form of the cylindrical capacitor is a measure of the flow rate in the test object 10.
  • the level in the measuring section 30 is detected by the capacitive sensor 30 at two successive times.
  • the change in level in the time between the two times is a measure of the leakage or the continuous flow.
  • FIG. 2 Another embodiment of a device for measuring hydraulic flow rates and leakages, shown in FIG. 2, differs from the device shown in FIG. 1 in that an inlet / outlet 48 of the measuring medium 50 is directly on the test object 10 on its side facing away from the measuring section 20 Side is arranged.
  • the inlet / outlet 48 is on the inlet side, i.e. the high pressure side, of the test object 10, while the test object 10 via its discharge side, i.e. Low pressure side, is directly coupled to the measuring section 20.
  • This device is independent of the operating pressure of the test specimen 10, so it can be used up to any high pressures.
  • a safety valve 100 is provided which, at very high operating pressures of the test specimen 10, prevents destructive or dangerous pressures from occurring in the measuring section 20, which is the case, for example, when the test specimen 10 no longer closes or is extremely leaky is.
  • the measurement is carried out by subjecting the test specimen 10 to a very high pressure (100 to 150 bar) on its high pressure side. In the event of leaks in the test specimen 10 or for measuring flow rates, this results in an increase in volume on the low pressure side, which is directly coupled to the measuring section 20. This results in a shift in the liquid level of the liquid measuring medium 50 in the measuring section 20, which is detected by the capacitive sensor 30, and thus in the present case also by the cylinder capacitor. In this case, the pressure prevailing in the pressure medium 70 corresponds to the atmospheric pressure.
  • the valve 61 is closed, whereas the return valve 42 is open.
  • the test specimen 10 can also be coupled to the measuring section 20 via a medium 120, which advantageously corresponds to the measuring medium 50. In this way, air trapping can be avoided in particular when coupling.
  • a line 130 and a valve 132 can be provided for rinsing the test specimen, which enable the test specimen 10 to be rinsed with the measurement medium 50 before the actual measurement.
  • a relief valve 150 is used to adjust the fill level in the measuring section 20.
  • the capacitance of the capacitive sensor 30 arranged in the measuring section 20 is measured as shown schematically in FIG. 3.
  • the capacitive sensor Cx, together with feedback and positive feedback resistors Rf, Rml, Rm2, is the frequency-determining element of a measuring oscillator (square wave generator) known per se.
  • the resulting period T of the oscillator is directly proportional to Cx.
  • a feedback resistor Rf 5 M ⁇
  • positive feedback resistors Rml, Rm2 230 k ⁇ , for example, T results in 230 ⁇ s, ie an oscillator frequency f of about 4.3 kHz.
  • the measuring oscillator signal corresponding to the probe capacity is fed to two counter chains, each comprising a counter 1 and a counter 2, the signal fed to a counter 2 being inverted.
  • a NAND gate 200 with two inputs is connected upstream of the counter chains.
  • a common 100 MHz signal from a reference oscillator is applied to each of the two inputs and is generated by a quartz oscillator module known per se.
  • the NAND gate of counter 1 allows the 100 MHz signal to pass during the time in which the output of the measuring oscillator is at HIGH. Since the measuring oscillator signal used for counter 2 is inverted, the NAND gate of counter 2 allows the 100 MHz signal to pass during the LOW phase of the measuring oscillator signal.
  • the counters 1, 2 of the two counter chains are each 16 bit counters.
  • a microcontroller reads the meter readings one after the other.
  • a difference to the reading in a previous measuring oscillator period is determined. This gives the length of the respective half (HIGH / LOW) of the measuring oscillator period in 10 ns units (100 MHz reference frequency).
  • a predetermined number of measured values are processed in a test stand computer (not shown) for the measurement.
  • the preselectable number of such measurements then creates a compensation curve with a constant, time-proportional and exponentially decaying term using the following formula:
  • Measured value constant + leakage * t + K * exp (-t / to).
  • the exponentially decaying term takes into account the effects which are generated, in particular, by trapped air in the test specimen 10 (adiabatic heating when the rinsing / test pressure is switched on and the subsequent reduction in volume due to cooling).
  • the time constant to is essentially only dependent on the test object 10 used, for example an injection valve family, and can therefore be determined beforehand in a generally applicable manner.
  • the size K is a measure of the volume of the enclosed air and can be monitored.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Power Engineering (AREA)
  • Thermal Sciences (AREA)
  • Electromagnetism (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Examining Or Testing Airtightness (AREA)
  • Measuring Fluid Pressure (AREA)

Abstract

The invention relates to a device for measuring hydraulic discharge and leakage in a test piece, comprising a measuring section configured as an inflow pipe approximately perpendicular to the test piece and a capacitive sensor located on the measuring section. Said sensor can be impinged upon by both at least one measuring medium and at least one other medium (pressure medium) designed to generate a pressure acting on the measuring medium. The invention aims to improve said device in such a way that it is possible to carry out precise measurements of discharge volumes and leakages using simple technology. To this end, the invention provides for the test piece to be coupled directly to the measuring section.

Description

Vorrichtung zur Messung von hydraulischen Durchfluß- mengen und Leckagen an einem PrüflingDevice for measuring hydraulic flow rates and leaks on a test object
Stand der TechnikState of the art
Die Erfindung betrifft eine Vorrichtung zur Messung von hydraulischen Durchflußmengen und Leckagen an einem Prüfling, umfassend eine als in etwa senkrecht verlaufende Zuleitung zu dem Prüfling ausgebildete Meßstrecke und einen in der Meßstrecke angeordneten kapazitiven Sensor, der sowohl von wenigstens einem Meßmedium als auch von wenigstens einem Medium zur Erzeugung eines auf das Meßmedium wirkenden Drucks (Druckmedium) beaufschlagbar ist.The invention relates to a device for measuring hydraulic flow rates and leaks on a test specimen, comprising a measuring section designed as an approximately vertical supply line to the test specimen and a capacitive sensor arranged in the measuring section, which detects both at least one measuring medium and at least one medium can be acted upon to generate a pressure (pressure medium) acting on the measuring medium.
Eine derartige Vorrichtung geht beispielsweise aus der DE 42 05 453 AI hervor. Bei dieser Vorrichtung ist die Meßstrecke über eine Verzweigung, in der ein Ventil angeordnet ist, mit dem Prüfling verbunden. Problematisch bei dieser Vorrichtung ist, daß Durchfluß- und Leckagemessungen nur mit begrenzter Genauigkeit möglich sind, da durch die Verzweigung und insbesondere durch das in der Verzweigung angeordnete Ventil Fehler, beispielsweise aufgrund von Undichtigkeiten dieses Ventils, auftreten können, die das Meßergebnis verfälschen.Such a device is shown for example from DE 42 05 453 AI. In this device, the measuring section is connected to the test object via a branch in which a valve is arranged. The problem with this device is that flow and leakage measurements are only possible with limited accuracy, because of the branching and in particular through the valve arranged in the branching, errors can occur, for example due to leaks in this valve, which falsify the measurement result.
Der Erfindung liegt daher die Aufgabe zugrunde, eine Vorrichtung zur Messung von hydraulischen Durchflußmengen und Leckagen an einem Prüfling der gattungsgemäßen Art derart zu verbessern, daß auf technisch einfach zu realisierende Weise präzise Messungen von Durchflußmengen und Leckagen möglich sind.The invention is therefore based on the object of improving a device for measuring hydraulic flow rates and leakages on a test specimen of the generic type in such a way that precise measurements of flow rates and leakages are possible in a technically simple manner.
Vorteile der ErfindungAdvantages of the invention
Diese Aufgabe wird bei einer Vorrichtung zur Messung von hydraulischen Durchflußmengen und Leckagen an einem Prüfling der eingangs beschriebenen Art erfindungsgemäß dadurch gelöst, daß der Prüfling unmittelbar an die Meßstrecke angekoppelt ist .This object is achieved according to the invention in a device for measuring hydraulic flow rates and leaks on a test specimen of the type described in the introduction in that the test specimen is coupled directly to the measuring section.
Das unmittelbare Ankoppeln des Prüflings an die Meßstrecke hat den großen Vorteil, daß einerseits eine sehr präzise Messung möglich ist und daß andererseits keine Verfälschung der Meßergebnisse stattfinden kann, die beispielsweise durch undichte Ventile, die zwischen dem Prüfling und der Meßstrecke angeordnet sind, hervorgerufen werden können.The direct coupling of the test object to the test section has the great advantage that, on the one hand, a very precise measurement is possible and, on the other hand, that the measurement results cannot be falsified, which can be caused, for example, by leaky valves which are arranged between the test object and the test section .
Insbesondere sind durch die direkte Ankopplung des Prüflings an die Meßstrecke auch sehr schnelle Messungen möglich, da beispielsweise durch zwischen dem Prüfling und der Meßstrecke angeordnete Verzweigungen, Ventile u.dgl. hervorgerufene, das Meßergebnis verfälschende Meßverzögerungen ausgeschlossen sind.In particular, the direct coupling of the test specimen to the test section also enables very fast measurements, since, for example, through branches arranged between the test specimen and the test section, Valves and the like caused measuring delays falsifying the measurement result are excluded.
Rein prinzipiell sind die unterschiedlichsten Anordnungen für einen Einlaß/Auslaß für das Druckmedium sowie für einen Einlaß/Auslaß für das Meßmedium denkbar .In principle, the most varied arrangements are conceivable for an inlet / outlet for the pressure medium and for an inlet / outlet for the measuring medium.
Eine vorteilhafte Ausführungsform sieht vor, daß der Einlaß/Auslaß für das Druckmedium und der Einlaß/Auslaß für das Meßmedium an einer dem Prüfling abgewandten Seite der Meßstrecke angeordnet sind.An advantageous embodiment provides that the inlet / outlet for the pressure medium and the inlet / outlet for the measuring medium are arranged on a side of the measuring section facing away from the test object.
Diese Anordnung erlaubt einerseits einen kompakten Aufbau der gesamten Meßvorrichtung, andererseits hochpräzise Messungen, da neben der Meßstrecke und dem Prüfling keine weiteren Aggregate im Prüfkreis angeordnet sind.On the one hand, this arrangement permits a compact construction of the entire measuring device, on the other hand, high-precision measurements, since in addition to the measuring section and the test object, no further units are arranged in the test circuit.
Ein anderes vorteilhaftes Ausführungsbeispiel sieht vor, daß der Einlaß/Auslaß für das Druckmedium auf der dem Prüfling abgewandten Seite der Meßstrecke und daß der Einlaß/Auslaß für das Meßmedium am Prüfling auf dessen der Meßstrecke abgewandten Seite angeordnet sind.Another advantageous exemplary embodiment provides that the inlet / outlet for the pressure medium are arranged on the side of the measuring section facing away from the test object and that the inlet / outlet for the measuring medium are arranged on the test object on the side thereof facing away from the measuring section.
Eine derartige Ausführungsform erlaubt auf besonders einfache Weise eine Messung von hydraulischen Durchflußmengen und Leckagen auf der Ablaufseite (Niederdruckseite) des Prüflings. Sie ist unabhängig vom Betriebsdruck des Prüflings und kann demnach bis zu beliebig hohen Drücken Verwendung finden. Insbesondere zur guten Ankopplung des unter Druck stehenden Meßmediums an den Prüfling und zur leichteren Ausspülung von eventuell entstehenden Luftblasen ist bei einem vorteilhaften Ausführungsbeispiel vorgesehen, daß zwischen dem Zulauf (der Hochdruckseite) des Prüflings und der Meßstrecke ein Verwirbelungselement zur Erzeugung einer Drehströmung in dem Prüfling angeordnet ist .Such an embodiment allows a particularly simple measurement of hydraulic flow rates and leaks on the discharge side (low pressure side) of the test object. It is independent of the operating pressure of the test object and can therefore be used up to any high pressure. In particular, for a good coupling of the pressurized measuring medium to the test object and for easier flushing out of any air bubbles that may arise, it is provided in an advantageous embodiment that a swirling element is arranged between the inlet (the high-pressure side) of the test object and the measuring section for generating a rotating flow in the test object is.
Was die Ausbildung des Verwirbelungselements betrifft, sind rein prinzipiell die unterschiedlichsten Ausführungsformen, welche eine Drehströmung in dem Prüfling erzeugen, denkbar. Eine vorteilhafte Ausführungsform sieht vor, daß das Verwirbelungselement eine zylindrische Scheibe mit in axialer und azimutaler Richtung geneigt angeordneten Öffnungen ist . Ein derartiges Verwirbelungselement ist einerseits besonders einfach herstellbar und erzeugt andererseits besonders effektive Drehströmungen in dem Prüfling.As far as the formation of the swirling element is concerned, in principle the most varied of embodiments which produce a rotary flow in the test specimen are conceivable. An advantageous embodiment provides that the swirling element is a cylindrical disc with openings inclined in the axial and azimuthal direction. Such a swirling element is on the one hand particularly easy to produce and on the other hand produces particularly effective three-way flows in the test specimen.
Vorzugsweise sind Absperrventile in den Einlaß- und Auslaßzuleitungen der Mediumversorgung angeordnet .Shut-off valves are preferably arranged in the inlet and outlet feed lines of the medium supply.
Hinsichtlich der Ausbildung der Meßstrecke sowie der Ausbildung des kapazitiven Sensors wurden bislang keine näheren Angaben gemacht. Ein vorteilhaftes Ausführungsbeispiel sieht vor, daß die Meßstrecke die Gestalt eines Zylinders hat und daß der kapazitive Sensor ein Zylinderkondensator ist. Auf diese Weise kann der kapazitive Sensor, der als Zylinderkondensator in der als Zylinder ausgebildeten Meßstrecke angeordnet ist, auf besonders einfache Weise von dem Meßmedium und dem Druckmedium beaufschlagt werden, da Meßstrecke und kapazitiver Sensor gewissermaßen "zusammenfallen". Rein prinzipiell können als Meßmedium sowie als Druckmedium die unterschiedlichsten Fluide verwendet werden.With regard to the design of the measuring section and the design of the capacitive sensor, no further details have so far been given. An advantageous embodiment provides that the measuring section has the shape of a cylinder and that the capacitive sensor is a cylinder capacitor. In this way, the capacitive sensor, which is arranged as a cylindrical capacitor in the measuring section formed as a cylinder, can be acted upon in a particularly simple manner by the measuring medium and the pressure medium, since the measuring section and capacitive sensor "coincide" to a certain extent. In principle, a wide variety of fluids can be used as the measuring medium and as the pressure medium.
Bei einer vorteilhaften Ausführungsform ist vorgesehen, daß das Meßmedium eine Hydraulikflüssigkeit ist und daß das Druckmedium Luft ist.In an advantageous embodiment it is provided that the measuring medium is a hydraulic fluid and that the pressure medium is air.
Bei einer anderen, insbesondere bei hohen Meßdrücken besonders vorteilhaft verwendbaren Aus ührungsform ist vorgesehen, daß das Meßmedium und das Druckmedium jeweils zwei nicht miteinander mischbare Flüssigkeiten sind.In another embodiment, which can be used particularly advantageously at high measuring pressures, it is provided that the measuring medium and the pressure medium are each two immiscible liquids.
Um Kurzschlüsse zu vermeiden ist vorzugsweise vorgesehen, daß eine der Elektroden des kapazitiven Sensors mit einem elektrisch isolierenden Überzug versehen ist.In order to avoid short circuits, it is preferably provided that one of the electrodes of the capacitive sensor is provided with an electrically insulating coating.
Zeichnungdrawing
Weitere Merkmale und Vorteile der Erfindung sind Gegenstand der nachfolgenden Beschreibung sowie der zeichnerischen Darstellung einiger Ausführungsbei- spiele .Further features and advantages of the invention are the subject of the following description and the graphic representation of some exemplary embodiments.
In der Zeichnung zeigen:The drawing shows:
Fig. 1 ein erstes Ausführungsbeispiel einer erfin- dungsgemäßen Vorrichtung zur Messung von hydraulischen Durchflußmengen und Leckagen an einem Prüfling; Fig. 2 ein zweites Ausführungsbeispiel einer erfindungsgemäßen Vorrichtung zur Messung von hydraulischen Durchflußmengen und Leckagen an einem Prüfling und1 shows a first exemplary embodiment of a device according to the invention for measuring hydraulic flow rates and leaks on a test specimen; Fig. 2 shows a second embodiment of a device according to the invention for measuring hydraulic flow rates and leaks on a test specimen and
Fig. 3 ein Prinzipschaltbild einer Auswerteschaltung, die bei den in Fig. 1 und Fig. 2 dargestellten erfindungsgemäßen Vorrichtungen zur Messung von hydraulischen Durchflußmengen und Leckagen einsetzbar ist.3 shows a basic circuit diagram of an evaluation circuit which can be used in the devices according to the invention for measuring hydraulic flow rates and leaks shown in FIGS. 1 and 2.
Beschreibung der AusführungsbeispieleDescription of the embodiments
Ein Ausführungsbeispiel einer Vorrichtung zur Messung von hydraulischen Durchflußmengen und Leckagen an einem Prüfling 10, beispielsweise einem in der Automobiltechnik verwendeten Einspritzventil, dargestellt in Fig. 1, umfaßt eine als in etwa senkrecht verlaufende Zuleitung zum Prüfling 10 ausgebildete Meßstrecke 20 und einen in der Meßstrecke 20 angeordneten kapazitiven Sensor 30 in Form eines Zylinderkondensators, dessen Außenzylinder 31 mit dem Außenrohr der Meßstrecke 20 zusammenfällt und dessen Mittelleiter 33 in dem Außenzylinder 31 und damit dem Außenrohr der Meßstrecke 20 im wesentlichen zentral angeordnet ist.An exemplary embodiment of a device for measuring hydraulic flow rates and leaks on a test object 10, for example an injection valve used in automotive technology, shown in FIG. 1, comprises a measuring section 20 designed as an approximately vertical supply line to the test object 10 and one in the measuring section 20 arranged capacitive sensor 30 in the form of a cylindrical capacitor, the outer cylinder 31 coincides with the outer tube of the measuring section 20 and the central conductor 33 is arranged centrally in the outer cylinder 31 and thus the outer tube of the measuring section 20.
Der Prüfling 10 ist über ein Dichtelement 12 unmittelbar an die Meßstrecke 20 angekoppelt.The test specimen 10 is coupled directly to the measuring section 20 via a sealing element 12.
An der dem Prüfling 10 zugewandten Seite des kapazitiven Sensors 30 ist eine elektrisch isolierte, perforierte Mittelleiterbefestigung 35 vorgesehen. An der dem Prüfling 10 abgewandten Seite des kapazitiven Sensors 30 ist der Mittelleiter 33 über eine elektrisch isolierende, druckdichte Durchführung 36 nach außen an die Auswerteschaltung geführt .An electrically insulated, perforated central conductor fastening 35 is provided on the side of the capacitive sensor 30 facing the test object 10. On the side of the capacitive sensor 30 facing away from the test specimen 10, the center conductor 33 is guided to the evaluation circuit via an electrically insulating, pressure-tight bushing 36.
An der dem Prüfling 10 abgewandten Seite der Meßstrecke 20 ist ein Einlaß/Auslaß 40 für ein Meßmedium 50 vorgesehen, über welche die Meßstrecke 20 und damit der kapazitive Sensor 30 in Form des Zylinderkondensators mit dem Meßmedium 50 beaufschlagbar sind.On the side of the measuring section 20 facing away from the test object 10, an inlet / outlet 40 is provided for a measuring medium 50, via which the measuring medium 20 and thus the capacitive sensor 30 in the form of the cylindrical capacitor can be acted upon with the measuring medium 50.
Der Einlaß/Auslaß 40 des Meßmediums 50 ist über ein erstes Ventil 41 sowie ein zweites Entlastungs- oder Rücklaufventil 42 verschließbar.The inlet / outlet 40 of the measuring medium 50 can be closed via a first valve 41 and a second relief or return valve 42.
Ferner ist auf der dem Prüfling 10 abgewandten Seite der Meßstrecke 20 ein Einlaß/Auslaß 60 vorgesehen, über den in die Meßstrecke 20 ein Medium zur Erzeugung eines auf das Meßmedium 50 wirkenden Drucks, d.h. ein Druckmedium 70, zuführbar ist. Der Einlaß/Auslaß 60 für das Druckmedium 70 ist über ein Ventil 61 verschließbar. Darüber hinaus kann in dem Einlaß/Auslaß 60 für das Druckmedium 70 dem Ventil 61 nachgeschaltet ein Manometer 64 zur Messung des in der Meßstrecke 20 herrschenden Drucks vorgesehen sein.Furthermore, an inlet / outlet 60 is provided on the side of the measuring section 20 facing away from the test specimen 10, via which an inlet / outlet 60 is provided in the measuring section 20 for generating a pressure acting on the measuring medium 50, i.e. a print medium 70, can be fed. The inlet / outlet 60 for the pressure medium 70 can be closed via a valve 61. In addition, a pressure gauge 64 for measuring the pressure prevailing in the measuring section 20 can be provided downstream of the valve 61 in the inlet / outlet 60 for the pressure medium 70.
Zwischen dem Prüfling 10 und der Meßstrecke 20 und damit dem kapazitiven Sensor 30 ist ferner ein Verwirbelungselement 80 zur Erzeugung einer Drehströmung in dem Prüfling 10 angeordnet. Durch diese Drehströmung werden insbesondere Blasen o.dgl., die bei Beaufschlagung des Prüflings 10 mit dem Meßmedium 50 entstehen können, aus dem Meßmedium 50 und dem Prüfling 10 ausgespült. Das Verwirbelungselement weist die Gestalt einer zylindrischen Scheibe mit in axialer und azimutaler Richtung geneigt angeordneten Öffnungen (nicht dargestellt) auf.A swirling element 80 for generating a rotary flow in the test specimen 10 is also arranged between the test specimen 10 and the measuring section 20 and thus the capacitive sensor 30. This rotary flow rinses out bubbles or the like, in particular, which may arise when the test sample 10 is exposed to the measuring medium 50, from the measuring medium 50 and the test sample 10. The swirling element has the shape a cylindrical disk with openings (not shown) arranged inclined in the axial and azimuthal direction.
Bei der in Fig. 1 dargestellten Vorrichtung, die für hydraulische Dichtheitsmessungen sehr geeignet ist, wird vorzugsweise als Meßmedium eine Hydraulikflüssigkeit und als Druckmedium Luft verwendet. Der Mittel- leiter 33 weist einen Durchmesser von etwa 0,5 mm auf, wohingegen der Außenzylinder 30 einen Durchmesser von etwa 2 mm aufweist. Die Länge des Zylinderkondensators beträgt etwa 100 mm.In the device shown in FIG. 1, which is very suitable for hydraulic tightness measurements, a hydraulic fluid is preferably used as the measuring medium and air as the pressure medium. The center conductor 33 has a diameter of approximately 0.5 mm, whereas the outer cylinder 30 has a diameter of approximately 2 mm. The length of the cylindrical capacitor is approximately 100 mm.
Falls das Meßmedium 50 elektrisch leitfähig ist, wird der Mittelleiter 33 mit einem dünnen, homogenen, elektrisch isolierenden Überzug 34 versehen.If the measuring medium 50 is electrically conductive, the center conductor 33 is provided with a thin, homogeneous, electrically insulating coating 34.
Eine derartige Vorrichtung ist insbesondere für die Messung geringer Durchflüsse besonders vorteilhaft, da sich im Prüfkreis nur das Dichtelement 12 zur Ankopplung des Prüflings befindet und insoweit keine Störungen entstehen können, die beispielsweise durch Leckagen von Aggregaten, die zwischen der Meßstrecke 20 und dem Prüfling 10 angeordnet sind, entstehen könnten.Such a device is particularly advantageous in particular for the measurement of low flow rates, since only the sealing element 12 for coupling the test specimen is located in the test circuit and, to that extent, no faults can arise, for example due to leakage of units arranged between the measuring section 20 and the test specimen 10 are, could arise.
Zur Messung wird zunächst das Meßmedium 50 über den Einlaß/Auslaß 40 bei geöffnetem Ventil 41 und geschlossenen Ventilen 42, 61 in die Meßstrecke 20 und den Prüfling 10 eingebracht. Der Prüfling 10 wird dabei über eine Ansteuerungsleitung 11 zur Spülung impuls- fδrmig geöffnet und geschlossen. Durch diesen Spülvorgang wird die gesamte Meßstrecke 20 und der Prüfling 10 mit dem Meßmedium 50 geflutet. Daraufhin werden die Ventile 61 und 42 geöffnet, und es wird durch Einblasen eines LuftStroms, d.h. des Druckmediums 70, der obere Bereich der Meßstrecke 20 ausgeblasen und getrocknet. Vorteilhafterweise ist die Auslaßbohrung des Einlasses/Auslasses 40 des Meßmediums 50 unterhalb der Einlaß/Auslaßbohrung des Einlasses/- Auslasses 60 des Druckmediums angeordnet, so daß eventuell in der Meßstrecke 20 vorhandenes Meßmedium 50 über den Einlaß/Auslaß 40 für das Meßmedium 50 auslaufen kann.For the measurement, the measuring medium 50 is first introduced into the measuring section 20 and the test object 10 via the inlet / outlet 40 with the valve 41 open and the valves 42, 61 closed. The device under test 10 is opened and closed in a pulsed manner via a control line 11 for rinsing. As a result of this rinsing process, the entire measuring section 20 and the test specimen 10 are flooded with the measuring medium 50. The valves 61 and 42 are then opened and the upper region of the measuring section 20 is blown out and dried by blowing in an air stream, ie the pressure medium 70. Advantageously, the outlet bore of the inlet / outlet 40 of the measuring medium 50 is arranged below the inlet / outlet bore of the inlet / outlet 60 of the pressure medium, so that any measuring medium 50 present in the measuring section 20 can run out via the inlet / outlet 40 for the measuring medium 50.
Zur Messung sind die Ventile 41, 42 in dem Einlaß/- Auslaß 40 des Meßmediums 50 geschlossen, während das Ventil 61 in dem Einlaß/Auslaß 60 des Druckmediums 70 geöffnet ist. Auf diese Weise wird die Meßstrecke 20 und der kapazitive Sensor 30 mit einem Prüfdruck p beaufschlagt, der durch das Manometer 64 erfaßt werden kann.For measurement, the valves 41, 42 in the inlet / outlet 40 of the measuring medium 50 are closed, while the valve 61 in the inlet / outlet 60 of the pressure medium 70 is open. In this way, the test section 20 and the capacitive sensor 30 are subjected to a test pressure p, which can be detected by the manometer 64.
Zur Messung der vom Prüfling 10 abgespritzten Flüssigkeitsmenge wird der Pegelstand des Meßmediums 50 durch den kapazitiven Sensor 30 erfaßt und an eine weiter unten näher zu beschreibende Auswerteschaltung weitergegeben.To measure the amount of liquid sprayed off by the test specimen 10, the level of the measuring medium 50 is detected by the capacitive sensor 30 and passed on to an evaluation circuit to be described in more detail below.
Der Prüfling 10 wird daraufhin gesteuert über eine Steuerleitung 11 geöffnet und es wird der Pegelstand des Meßmediums 50 durch den kapazitiven Sensor 30 erneut erfaßt .The device under test 10 is then opened in a controlled manner via a control line 11 and the level of the measuring medium 50 is detected again by the capacitive sensor 30.
Die Pegelstandsänderung in der Meßstrecke 20 und damit in dem kapazitiven Sensor 30 in Form des Zylinderkondensators ist ein Maß für die Durchflußmenge in dem Prüfling 10. Für eine Bestimmung einer Leckage oder eines kontinuierlichen Durchflusses in dem Prüfling 10 wird der Pegelstand in der Meßstrecke 30 durch den kapazitiven Sensor 30 an zwei aufeinanderfolgenden Zeitpunkten erfaßt. Die Pegeländerung in der zwischen den beiden Zeitpunkten liegenden Zeit ist ein Maß für die Leckage oder den kontinuierlichen Durchfluß.The change in level in the measuring section 20 and thus in the capacitive sensor 30 in the form of the cylindrical capacitor is a measure of the flow rate in the test object 10. To determine a leak or a continuous flow in the test object 10, the level in the measuring section 30 is detected by the capacitive sensor 30 at two successive times. The change in level in the time between the two times is a measure of the leakage or the continuous flow.
Ein anderes Ausführungsbeispiel einer Vorrichtung zur Messung von hydraulischen Durchflußmengen und Leckagen, dargestellt in Fig. 2, unterscheidet sich von der in Fig. 1 dargestellten Vorrichtung dadurch, daß ein Einlaß/Auslaß 48 des Meßmediums 50 direkt am Prüfling 10 auf dessen der Meßstrecke 20 abgewandter Seite angeordnet ist. Dabei ist der Einlaß/Auslaß 48 an der Zulaufseite, d.h. der Hochdruckseite, des Prüflings 10 angeordnet, während der Prüfling 10 über seine Ablauf- seite, d.h. Niederdruckseite, unmittelbar an die Meßstrecke 20 angekoppelt ist. Diese Vorrichtung ist unabhängig vom Betriebsdruck des Prüflings 10, kann also bis zu beliebig hohen Drücken Verwendung finden.Another embodiment of a device for measuring hydraulic flow rates and leakages, shown in FIG. 2, differs from the device shown in FIG. 1 in that an inlet / outlet 48 of the measuring medium 50 is directly on the test object 10 on its side facing away from the measuring section 20 Side is arranged. The inlet / outlet 48 is on the inlet side, i.e. the high pressure side, of the test object 10, while the test object 10 via its discharge side, i.e. Low pressure side, is directly coupled to the measuring section 20. This device is independent of the operating pressure of the test specimen 10, so it can be used up to any high pressures.
Wie in Fig. 2 dargestellt, ist ein Sicherheitsventil 100 vorgesehen, das bei sehr hohen Betriebsdrücken des Prüflings 10 verhindert, daß in der Meßstrecke 20 zerstörende oder gefährliche Drücke entstehen, was beispielsweise der Fall ist, wenn der Prüfling 10 nicht mehr schließt oder extrem undicht ist.As shown in FIG. 2, a safety valve 100 is provided which, at very high operating pressures of the test specimen 10, prevents destructive or dangerous pressures from occurring in the measuring section 20, which is the case, for example, when the test specimen 10 no longer closes or is extremely leaky is.
Die Messung erfolgt dadurch, daß der Prüfling 10 auf seiner Hochdruckseite mit einem sehr hohen Druck (100 bis 150 bar) beaufschlagt wird. Bei Undichtigkeiten des Prüflings 10 oder zur Messung von Durchflußmengen wird hierdurch eine Volumenzunahme auf der Niederdruckseite, die unmittelbar an die Meßstrecke 20 angekoppelt ist, hervorgerufen. Hierdurch ergibt sich eine Verschiebung des Flüssigkeitsstands des flüssigen Meßmediums 50 in der Meßstrecke 20, die von dem kapazitiven Sensor 30, und damit im vorliegenden Falle auch von dem Zylinderkondensator, erfaßt wird. Der in dem Druckmedium 70 herrschende Druck entspricht in diesem Fall dem Atmosphärendruck. Das Ventil 61 ist geschlossen, wohingegen das Rücklaufventil 42 geöffnet ist.The measurement is carried out by subjecting the test specimen 10 to a very high pressure (100 to 150 bar) on its high pressure side. In the event of leaks in the test specimen 10 or for measuring flow rates, this results in an increase in volume on the low pressure side, which is directly coupled to the measuring section 20. This results in a shift in the liquid level of the liquid measuring medium 50 in the measuring section 20, which is detected by the capacitive sensor 30, and thus in the present case also by the cylinder capacitor. In this case, the pressure prevailing in the pressure medium 70 corresponds to the atmospheric pressure. The valve 61 is closed, whereas the return valve 42 is open.
Wie in Fig. 2 gestrichelt dargestellt ist, kann der Prüfling 10 auch über ein Medium 120, das vorteilhafterweise dem Meßmedium 50 entspricht, an die Meßstrecke 20 angekoppelt sein. Auf diese Weise kann insbesondere bei der Ankopplung ein Lufteinschluß vermieden werden. Darüber hinaus kann eine Leitung 130 und ein Ventil 132 zur Spülung des Prüflings vorgesehen sein, welche vor der eigentlichen Messung das Spülen des Prüflings 10 mit dem Meßmedium 50 ermöglichen.As shown in dashed lines in FIG. 2, the test specimen 10 can also be coupled to the measuring section 20 via a medium 120, which advantageously corresponds to the measuring medium 50. In this way, air trapping can be avoided in particular when coupling. In addition, a line 130 and a valve 132 can be provided for rinsing the test specimen, which enable the test specimen 10 to be rinsed with the measurement medium 50 before the actual measurement.
Ein Entlastungsventil 150 dient zur Einstellung des Füllstands in der Meßstrecke 20.A relief valve 150 is used to adjust the fill level in the measuring section 20.
Die Messung der Kapazität des in der Meßstrecke 20 angeordneten kapazitiven Sensors 30 erfolgt wie in Fig. 3 schematisch dargestellt. Der kapazitive Sensor Cx ist zusammen mit Rück- und Mitkopplungswiderständen Rf, Rml, Rm2 freguenzbestimmendes Element eines an sich bekannten Meßoszillators (Rechteckgenerators) . Die sich ergebende Periodendauer T des Oszillators ist dabei direkt proportional zu Cx. Mit einer Kapazität Cx von etwa 20 pF, einem Rückkopplungswiderstand Rf = 5 MΩ, Mitkopplungswiderständen Rml, Rm2 = 230 kΩ ergibt sich beispielsweise T zu 230 μs , d.h. eine Oszillator- frequenz f von etwa 4,3 kHz. Das der Sondenkapazität entsprechende Meßoszillatorsignal wird zwei Zählerketten umfassend jeweils einen Zähler 1 und einen Zähler 2 zugeführt, wobei das einem Zähler 2 zugeführte Signal invertiert wird. Den Zählerketten ist jeweils ein NAND- Gatter 200 mit zwei Eingängen vorgeschaltet. Auf jeweils einen der beiden Eingänge wird ein gemeinsames 100 MHz-Signal eines Referenzoszillators gelegt, das über einen an sich bekannten Quarz-Oszillatorbaustein erzeugt wird. Das NAND-Gatter des Zählers 1 läßt dabei das 100 MHz-Signal während der Zeit passieren, in der der Ausgang des Meßoszillators auf HIGH liegt. Da das für den Zähler 2 verwendete Meßoszillatorsignal invertiert ist, läßt das NAND-Gatter des Zählers 2 das 100 MHz -Signal während der LOW-Phase des Meßoszillatorsignals passieren.The capacitance of the capacitive sensor 30 arranged in the measuring section 20 is measured as shown schematically in FIG. 3. The capacitive sensor Cx, together with feedback and positive feedback resistors Rf, Rml, Rm2, is the frequency-determining element of a measuring oscillator (square wave generator) known per se. The resulting period T of the oscillator is directly proportional to Cx. With a capacitance Cx of approximately 20 pF, a feedback resistor Rf = 5 MΩ, positive feedback resistors Rml, Rm2 = 230 kΩ, for example, T results in 230 μs, ie an oscillator frequency f of about 4.3 kHz. The measuring oscillator signal corresponding to the probe capacity is fed to two counter chains, each comprising a counter 1 and a counter 2, the signal fed to a counter 2 being inverted. A NAND gate 200 with two inputs is connected upstream of the counter chains. A common 100 MHz signal from a reference oscillator is applied to each of the two inputs and is generated by a quartz oscillator module known per se. The NAND gate of counter 1 allows the 100 MHz signal to pass during the time in which the output of the measuring oscillator is at HIGH. Since the measuring oscillator signal used for counter 2 is inverted, the NAND gate of counter 2 allows the 100 MHz signal to pass during the LOW phase of the measuring oscillator signal.
Die Zähler 1, 2 der beiden Zählerketten sind jeweils 16 bit-Zähler. Ein Microcontroller liest die Zählerstände nacheinander aus.The counters 1, 2 of the two counter chains are each 16 bit counters. A microcontroller reads the meter readings one after the other.
Es wird eine Differenz zur Ablesung in einer vorhergehenden Meßoszillatorperiode ermittelt. Diese ergibt die Länge der jeweiligen Hälfte (HIGH/LOW) der Meßoszillatorperiode in 10 ns-Einheiten (100 MHz-Referenzfre- quenz) . Die Addition der jeweils anderen, vorher gemessenen Halbperiode ergibt nach Messung jeder Halbperiode die momentane ganze Meßoszillatorperiode T in 10 ns-Einheiten. Für die oben erwähnte Zeitkonstante T = 230 μs ergibt sich demnach eine Periode zu etwa 23000.A difference to the reading in a previous measuring oscillator period is determined. This gives the length of the respective half (HIGH / LOW) of the measuring oscillator period in 10 ns units (100 MHz reference frequency). The addition of the other, previously measured half-period results after measurement of each half-period the instantaneous whole measuring oscillator period T in 10 ns units. For the above-mentioned time constant T = 230 μs, this results in a period of around 23,000.
Durch diese Art der verschachtelten Ablesung der Zählerketten ergibt sich eine sehr hohe zeitliche Auflösung (typischerweise beträgt diese etwa 120 μs) . Auf diese Weise sind sehr schnelle Messungen möglich, die insbesondere mit der oben anhand von Fig.l beschriebenen Vorrichtung meßtechnisch besonders gut durchführbar sind.This type of interleaved reading of the meter chains results in a very high time Resolution (typically around 120 μs). In this way, very fast measurements are possible, which can be carried out particularly well in terms of measurement technology, particularly with the device described above with reference to FIG.
Zur Messung wird eine vorgegebene Anzahl von Meßwerten in einem PrüfStandsrechner (nicht dargestellt) verarbeitet. Durch die vorwählbare Anzahl solcher Messungen wird dann eine Ausgleichskurve mit einem konstanten, zeitproportional und exponentiell abklingenden Term gelegt nach folgender Formel :A predetermined number of measured values are processed in a test stand computer (not shown) for the measurement. The preselectable number of such measurements then creates a compensation curve with a constant, time-proportional and exponentially decaying term using the following formula:
Meßwert = Konstante + Undichtheit * t + K * exp(-t/to) .Measured value = constant + leakage * t + K * exp (-t / to).
Der exponentiell abklingende Term trägt den Effekten Rechnung, welche insbesondere durch eingeschlossene Luft im Prüfling 10 erzeugt werden (adiabatische Erwärmung beim Aufschalten des Spül -/Prüfdruckes und nachfolgende Volumenverringerung durch Abkühlung) . Die Zeitkonstante to ist im wesentlichen nur abhängig von dem verwendeten Prüfling 10, beispielsweise einer Einspritzventil-Familie, und kann daher vorher allgemeingültig bestimmt werden. Die Größe K ist ein Maß für das Volumen der eingeschlossenen Luft und kann überwacht werden.The exponentially decaying term takes into account the effects which are generated, in particular, by trapped air in the test specimen 10 (adiabatic heating when the rinsing / test pressure is switched on and the subsequent reduction in volume due to cooling). The time constant to is essentially only dependent on the test object 10 used, for example an injection valve family, and can therefore be determined beforehand in a generally applicable manner. The size K is a measure of the volume of the enclosed air and can be monitored.
Für langsame Messungen werden pro Meßwerterfassung typischerweise 80 Meßoszillatorperioden ausgelesen. Bei Mittelung über die letzten 10 Messungen im Abstand von typischerweise 50 bis 200 ms ergibt sich ein Meßwert von etwa 18.000.000 für eine gut gefüllte Sonde. Für eine leere Sonde ergibt sich etwa 15.000.000. Damit ist auch der Füllgrad der Sonde erkennbar, d.h. eine Erkennung von Störungen in der Versorgung des Meßmediums 50, eine Erkennung von einem Grobleck am Prüfling 10, ein zu hoher Lufteinschluß u.dgl..For slow measurements, typically 80 measuring oscillator periods are read out per measured value acquisition. Averaging over the last 10 measurements at a distance of typically 50 to 200 ms results in a measured value of approximately 18,000,000 for a well-filled probe. The result for an empty probe is approximately 15,000,000. This also shows the degree of filling of the probe, ie one Detection of malfunctions in the supply of the measuring medium 50, detection of a large leak on the test object 10, excessive air inclusion and the like.
Es versteht sich, daß auch standardmäßige, langsame Messungen, z.B. Dichtheitsprüfungen oder integrale Messungen von dynamischen oder statischen Durchflüssen durch entsprechende Meßprogramme, die im Microcontroller festgelegt sind, möglich sind. Hierbei können aufgrund der Möglichkeit der schnellen Messung eine Vielzahl von Messungen addiert und deren gegebenenfalls gewichteter Mittelwert bestimmt werden. It is understood that standard slow measurements, e.g. Leakage tests or integral measurements of dynamic or static flows are possible using appropriate measurement programs that are defined in the microcontroller. Due to the possibility of rapid measurement, a large number of measurements can be added and their weighted average value determined if necessary.

Claims

Patentansprüche claims
Vorrichtung zur Messung von hydraulischen Durchflußmengen und Leckagen an einem Prüfling (10) , umfassend eine als in etwa senkrecht verlaufende Zuleitung zum Prüfling (10) ausgebildete Meßstrecke (20) und einen in der Meßstrecke (20) angeordneten kapazitiven Sensor (30) , der sowohl von wenigstens einem Meßmedium (50) als auch von wenigstens einem Medium zur Erzeugung eines auf das Meßmedium (50) wirkenden Drucks (Druckmedium 70) beaufschlagbar ist, dadurch gekennzeichnet, daß der Prüfling (10) unmittelbar an die Meßstrecke (20) angekoppelt ist.Device for measuring hydraulic flow rates and leaks on a test specimen (10), comprising a measuring section (20) designed as an approximately vertical supply line to the test specimen (10) and a capacitive sensor (30) arranged in the measuring section (20) At least one measuring medium (50) and at least one medium for generating a pressure (pressure medium 70) acting on the measuring medium (50) can be acted on, characterized in that the test specimen (10) is coupled directly to the measuring section (20).
Vorrichtung nach Anspruch 1, dadurch gekennzeichnet, daß ein Einlaß/Auslaß (60) für das Druckmedium (70) und ein Einlaß/Auslaß (40) für das Meßme- dium (50) an einer dem Prüfling (10) abgewandten- Seite der Meßstrecke (20) angeordnet sind.Apparatus according to claim 1, characterized in that an inlet / outlet (60) for the pressure medium (70) and an inlet / outlet (40) for the measuring Dium (50) are arranged on a side of the test section (20) facing away from the test object (10).
3. Vorrichtung nach Anspruch 1, dadurch gekennzeichnet, daß ein Einlaß/Auslaß (48) für das Meßmedium (50) an dem Prüfling (10) auf dessen der Meßstrecke (20) abgewandten Seite und daß der Einlaß/Auslaß (60) für das Druckmedium (70) auf der dem Prüfling (10) abgewandten Seite der Meßstrecke (20) angeordnet sind.3. Apparatus according to claim 1, characterized in that an inlet / outlet (48) for the measuring medium (50) on the test specimen (10) on its side facing away from the measuring section (20) and that the inlet / outlet (60) for the Pressure medium (70) are arranged on the side of the measuring section (20) facing away from the test object (10).
4. Vorrichtung nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß zwischen dem Zulauf des Prüflings (10) und der Meßstrecke (20) ein Verwirbelungselement (80) zur Erzeugung einer Drehströmung in dem Prüfling (10) angeordnet ist.4. Apparatus according to claim 1 or 2, characterized in that between the inlet of the test specimen (10) and the measuring section (20) a swirling element (80) for generating a rotary flow in the test specimen (10) is arranged.
5. Vorrichtung nach Anspruch 4, dadurch gekennzeichnet, daß das Verwirbelungselement (80) eine zylindrische Scheibe mit in axialer und azimutaler Richtung geneigt angeordneten Öffnungen ist.5. The device according to claim 4, characterized in that the swirling element (80) is a cylindrical disc with openings inclined in the axial and azimuthal direction.
6. Vorrichtung nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß in den Zuleitungen der Einlasse und Auslässe (40, 60) Absperrventile (41, 42, 61) angeordnet sind.6. Device according to one of claims 1 to 5, characterized in that in the feed lines of the inlets and outlets (40, 60) shut-off valves (41, 42, 61) are arranged.
7. Vorrichtung nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß die Meßstrecke (20) die Gestalt eines Zylinders hat und daß der kapazitive Sensor (30) ein Zylinderkondensator ist . 7. Device according to one of claims 1 to 5, characterized in that the measuring section (20) has the shape of a cylinder and that the capacitive sensor (30) is a cylinder capacitor.
8. Vorrichtung nach einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, daß das Meßmedium (50) eine Hydraulikflüssigkeit ist und daß das Druckmedium (70) Luft ist.8. Device according to one of claims 1 to 7, characterized in that the measuring medium (50) is a hydraulic fluid and that the pressure medium (70) is air.
9. Vorrichtung nach einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, daß das Meßmedium (50) und das Druckmedium (70) jeweils zwei nicht miteinander mischbare Flüssigkeiten sind.9. Device according to one of claims 1 to 7, characterized in that the measuring medium (50) and the pressure medium (70) are each two immiscible liquids.
10. Vorrichtung nach einem der Ansprüche 1 bis 9, dadurch gekennzeichnet, daß eine der Elektroden des kapazitiven Sensors (30) mit einem elektrisch isolierenden Überzug (34) versehen ist. 10. Device according to one of claims 1 to 9, characterized in that one of the electrodes of the capacitive sensor (30) is provided with an electrically insulating coating (34).
EP97949961A 1997-03-07 1997-11-27 Device for measuring hydraulic discharge volumes and leakages in a test piece Withdrawn EP0922202A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE1970942 1997-03-07
DE19709422A DE19709422B4 (en) 1997-03-07 1997-03-07 Device for measuring hydraulic flow rates and leakages on a test specimen
PCT/DE1997/002772 WO1998040700A1 (en) 1997-03-07 1997-11-27 Device for measuring hydraulic discharge volumes and leakages in a test piece

Publications (1)

Publication Number Publication Date
EP0922202A1 true EP0922202A1 (en) 1999-06-16

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EP97949961A Withdrawn EP0922202A1 (en) 1997-03-07 1997-11-27 Device for measuring hydraulic discharge volumes and leakages in a test piece

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US (1) US6189377B1 (en)
EP (1) EP0922202A1 (en)
JP (1) JP2000509833A (en)
KR (1) KR20000010782A (en)
DE (1) DE19709422B4 (en)
WO (1) WO1998040700A1 (en)

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Also Published As

Publication number Publication date
KR20000010782A (en) 2000-02-25
US6189377B1 (en) 2001-02-20
WO1998040700A1 (en) 1998-09-17
DE19709422B4 (en) 2011-02-17
JP2000509833A (en) 2000-08-02
DE19709422A1 (en) 1998-09-10

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