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)
• Electromagnetism (AREA)
• Thermal Sciences (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)

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• 1997
  • 1997-03-07 DE DE19709422A patent/DE19709422B4/de not_active Expired - Fee Related
  • 1997-11-27 JP JP10539038A patent/JP2000509833A/ja active Pending
  • 1997-11-27 KR KR1019980708908A patent/KR20000010782A/ko not_active Application Discontinuation
  • 1997-11-27 WO PCT/DE1997/002772 patent/WO1998040700A1/de not_active Application Discontinuation
  • 1997-11-27 EP EP97949961A patent/EP0922202A1/de not_active Withdrawn
  • 1997-11-27 US US09/180,445 patent/US6189377B1/en not_active Expired - Fee Related

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